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Sample records for catalytic oxidative dehydrogenation

  1. Catalytic Conversion of Methanol by Oxidative Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This study investigates the effects of addition of oxygen on the oxidative dehydrogenation (ODH) of methanol when a fluorotetrasilicic mica ion-exchanged with palladium (Pd2+-TSM) was used as the catalyst. The reaction proceeded at a very low temperature in the presence of oxygen, and HCOOCH3 was obtained at high selectivity. By calculating the equilibrium conversion, it has been shown that substantial ODH took place for HCOOCH3 production. Consequently, this reaction would make dehydrogenation the dominant reaction at equilibrium. Not all the H dissociated from CH3OH was converted to H2O by oxidation. It has been shown that the H2O was not produced from oxidative dehydrogenation by the direct reaction of CH3OH and O2 when an attempt was made to carry out oxidative dehydrogenation using an isotope oxygen trace method in the gas phase. Therefore, when CH3OH was converted to CO2 and dehydrogenated to HCOOCH3, the C-O bonds were not dissociated.

  2. The chemical origin and catalytic activity of coinage metals: from oxidation to dehydrogenation.

    Science.gov (United States)

    Syu, Cih-Ying; Yang, Hao-Wen; Hsu, Fu-Hsing; Wang, Jeng-Han

    2014-04-28

    The high oxidation activity of coinage metals (Cu, Ag and Au) has been widely applied in various important reactions, such as oxidation of carbon monoxide, alkenes or alcohols. The catalytic behavior of those inert metals has mostly been attributable to their size effect, the physical effect. In the present study, the chemical effects on their high oxidation activity have been investigated. We mechanistically examine the direct and oxidative dehydrogenation (partial oxidation) reactions of ethanol to acetaldehyde on a series of transition metals (groups 9, 10 and 11) with identical physical characteristics and varied chemical origins using density functional theory (DFT) calculations and electronic structure analyses at the GGA-PW91 level. The energetic results show that coinage metals have much lower activation energies and higher exothermicities for the oxidative dehydrogenation steps although they have higher energy for the direct dehydrogenation reaction. In the electronic structure analyses, coinage metals with saturated d bands can efficiently donate electrons to O* and OH*, or other electronegative adspecies, and better promote their p bands to higher energy levels. The negatively charged O* and OH* with high-lying p bands are responsible for lowering the energies in oxidative steps. The mechanistic understanding well explains the better oxidation activity of coinage metals and provides valuable information on their utilization in other useful applications, for example, the dehydrogenation process. PMID:24626959

  3. Heterogeneous catalytic oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Badstube, T.; Papp, H. [Leipzig Univ. (Germany). Inst. fuer Technische Chemie; Kustrowski, P.; Dziembaj, R. [Jagiellonian Univ., Crakow (Poland). Faculty of Chemistry

    1998-12-31

    Alkaline promoted active carbon supported iron catalysts are very active in the oxidative dehydrogenation of ethylbenzene to styrene in the presence of carbon dioxide. The best results were obtained at 550 C for a Li-promoted catalyst with a conversion of ethylbenzene of 75% and a selectivity towards styrene of nearly 95%. These results are better than those obtained with industrial catalysts which perform the dehydrogenation process with an excess of water. The main product of the dehydrogenation reaction with CO{sub 2} was styrene, but the following by-products were detected - benzene and toluene. The selectivity towards toluene was always higher than towards benzene. We observed also the formation of carbon monoxide and water, which were produced with a constant molar ratio of about 0.8. The weight of the catalysts increased up to 20% during the reaction due to deposition of carbon. Using a too large excess of CO{sub 2} (CO{sub 2}/EB>10) was harmful for the styrene yield. The most favorable molar ratio of CO{sub 2} to EB was 10:1. No correlation between the molar ratios of reactants and the amount of deposited coke on the surface of catalysts was observed. The highest catalytic activity showed iron loaded D-90 catalysts which were promoted with alkali metals in a molar ratio of 1:10. Iron, nickel and cobalt loaded carbonized PPAN, PC, inorganic supports like Al{sub 2}O{sub 3}, SiO{sub 2}/ZrO{sub 2} or TiO{sub 2} respectively and commercial iron catalysts applied for styrene production did not show comparable catalytic activity in similar conditions. (orig.)

  4. Catalytic propane dehydrogenation over In₂O₃–Ga₂O₃ mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Shuai; Gil, Laura Briones; Subramanian, Nachal; Sholl, David S.; Nair, Sankar; Jones, Christopher W.; Moore, Jason S.; Liu, Yujun; Dixit, Ravindra S.; Pendergast, John G. (Dow); (GIT)

    2015-08-26

    We have investigated the catalytic performance of novel In₂O₃–Ga₂O₃ mixed oxides synthesized by the alcoholic-coprecipitation method for propane dehydrogenation (PDH). Reactivity measurements reveal that the activities of In₂O₃–Ga₂O₃ catalysts are 1–3-fold (on an active metal basis) and 12–28-fold (on a surface area basis) higher than an In₂O₃–Al₂O₃ catalyst in terms of C₃H₈ conversion. The structure, composition, and surface properties of the In₂O₃–Ga₂O₃ catalysts are thoroughly characterized. NH₃-TPD shows that the binary oxide system generates more acid sites than the corresponding single-component catalysts. Raman spectroscopy suggests that catalysts that produce coke of a more graphitic nature suppress cracking reactions, leading to higher C₃H₆ selectivity. Lower reaction temperature also leads to higher C₃H₆ selectivity by slowing down the rate of side reactions. XRD, XPS, and XANES measurements, strongly suggest that metallic indium and In₂O₃ clusters are formed on the catalyst surface during the reaction. The agglomeration of In₂O₃ domains and formation of a metallic indium phase are found to be irreversible under O₂ or H₂ treatment conditions used here, and may be responsible for loss of activity with increasing time on stream.

  5. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    International Nuclear Information System (INIS)

    Highlights: • Vanadia supported on titanate nanotube shows enhanced dispersion of vanadia. • Deactivatoin during propane ODH related to the rutile development. • Titanate nanotube transfers to anatase due to calcinations and presence of vanadia. - Abstract: Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V2O5 catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere

  6. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Kootenaei, A.H. Shahbazi [Department of Chemical Engineering, College of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Towfighi, J., E-mail: towfighi@modares.ac.ir [Department of Chemical Engineering, College of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Khodadadi, A.; Mortazavi, Y. [Catalysis and Nanostructured Materials Laboratory, Oil and Gas Processing Center of Excellence, Department of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11365-4563, Tehran (Iran, Islamic Republic of)

    2014-04-01

    Highlights: • Vanadia supported on titanate nanotube shows enhanced dispersion of vanadia. • Deactivatoin during propane ODH related to the rutile development. • Titanate nanotube transfers to anatase due to calcinations and presence of vanadia. - Abstract: Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V{sub 2}O{sub 5} catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere.

  7. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    Science.gov (United States)

    Kootenaei, A. H. Shahbazi; Towfighi, J.; Khodadadi, A.; Mortazavi, Y.

    2014-04-01

    Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V2O5 catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere.

  8. Catalytic dehydrogenations of ethylbenzene to styrene

    NARCIS (Netherlands)

    Nederlof, C.

    2012-01-01

    This research work on the catalytic dehydrogenation of ethylbenzene (EB) to styrene (ST) had a primary goal of developing improved catalysts for dehydrogenation processes both in CO2 as well as with O2 that can compete with the conventional dehydrogenation process in steam. In order to achieve this

  9. Modifications induced by potassium addition on chromia/alumina catalysts and their influence on the catalytic activity for the oxidative dehydrogenation of propane

    International Nuclear Information System (INIS)

    The oxidative dehydrogenation of propane was investigated on K-containing chromia/alumina catalysts, with nominal Cr and K loadings of 10 and 0-2 wt%, respectively. Their chemical composition, structure, texture, nature of surface species, redox features and surface acidity were determined. Catalytic behaviour was investigated in a continuous-flow micro-reactor under different conditions. Besides the nature and concentration of the chromium species, potassium addition was found to affect the reducibility of the catalysts as well as their acid surface features. Such modifications were found to condition the catalytic behaviour, which appeared somewhat peculiar in comparison with that of the catalytic systems reported in literature.

  10. A La-doped Mg-Al mixed metal oxide supported copper catalyst with enhanced catalytic performance in transfer dehydrogenation of 1-decanol.

    Science.gov (United States)

    Zhang, Ming; Zhao, Yajie; Liu, Qian; Yang, Lan; Fan, Guoli; Li, Feng

    2016-01-21

    In the present work, a La-doped Mg-Al mixed metal oxide supported copper catalyst (Cu/La-MgAlO) was synthesized through a layered double hydroxide precursor route. The materials were characterized by powder X-ray diffraction, transmission electron microscopy, CO2-temperature programmed desorption, Fourier transform infrared spectra of CO2 absorption, and X-ray photoelectron spectroscopy. The results revealed that the introduction of a trace amount of La could significantly improve the surface basicity of the Cu/La-MgAlO catalyst, especially strong Lewis basicity. Compared with the undoped supported Cu catalyst, Cu/La-MgAlO exhibited much higher activity and selectivity in the liquid-phase transfer dehydrogenation of 1-decanol with a 1-decanal yield up to 89%. The excellent catalytic efficiency was mainly ascribed to the surface cooperation between the Lewis basic sites and the adjacent Cu(0)/Cu(+) species. That is, basic sites, especially strong-strength basic sites, held the key to the abstraction of protons from the hydroxyl group in 1-decanol, while the adjacent Cu(0) and Cu(+) species were responsible for the hydrogen transfer and the adsorption of styrene in the transfer dehydrogenation and hydrogenation reactions, respectively. This study provides a new method for designing cost-effective supported copper-based catalysts highly efficient for the transfer dehydrogenation of primary aliphatic alcohols by modifying the surface basicity of metal oxide supports. PMID:26659760

  11. Oxidative dehydrogenation of light alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Meiswinkel, A.; Thaller, C.; Bock, M.; Alvarado, L. [Linde AG, Pullach (Germany); Hartmann, D.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen (Germany)

    2012-07-01

    The demand of light olefins increases steadily and the current steam cracking production is highly energy demanding. This motivates the development of alternative production processes like the oxidative dehydrogenation (ODH) of light alkanes operating at comparably low temperatures. Multi-component oxides are reported to show excellent catalytic performance in the ODH. Especially, MoVTeNbO oxides present high activity and selectivity in ODH of ethane. Synthesis of MoVTeNb oxides was done by a hydrothermal method. Qualitative and quantitative phase analysis were performed by X-ray diffraction and Rietveld refinement. Surface compositions were determined by Low energy ion scattering (LEIS). Catalytic tests were carried out in a fixed bed plug flow reactor using ethane and oxygen diluted in helium, as gaseous feed. Based on laboratory investigations a first upscale to a bench-top-pilot unit was performed in order to evaluate the large scale and long term feasibility of the process under technically relevant conditions. MoVTeNb oxides show high activity combined with excellent selectivity in the ODH of ethane to ethylene (S > 95% at X < 40%). Phase analysis reveals the presence of M1, M2 and amorphous phases. Literature reports the crystalline M1 phase as essential for the performance. Indeed, the crystalline M1 phase impacts on the activity via exposing V on the surface being apparently vital to achieve an active material. A correlation of the apparent activation energy with the surface vanadium composition of the catalysts is noticed, however, surprisingly with no major impact on the ethene selectivity. As this material was identified as most promising for a technical application a scale up from less than 1g to 50g of catalyst was performed in a bench-top-pilot unit. The reaction has a significant adiabatic temperature rise and the handling of the reaction heat is a major challenge for process engineering. Furthermore different diluent media such as Helium, Nitrogen

  12. Atomization energy approach to the quantitative evaluation of catalytic activities of metal oxides during dehydrogenation of MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hirate, H., E-mail: hirate@silky.numse.nagoya-u.ac.jp [Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-Cho, Chikusa-Ku, Nagoya 464-8603 (Japan); Morinaga, M.; Yukawa, H. [Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-Cho, Chikusa-Ku, Nagoya 464-8603 (Japan); Nakai, H. [Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Okubo, Shinjuku-ku, Tokyo, 169-8555 (Japan)

    2011-09-15

    Research highlights: > Study of catalytic reaction on MgH{sub 2} and NaAlH{sub 4} using atomization energy concept. > Quantitative evaluation of catalytic activities of metal oxide for MgH{sub 2}. > Quantitative evaluation of catalytic activities of metal chlorides for NaAlH{sub 4}. > Observation of the O-H stretching mode on Nb{sub 2}O{sub 5}-catalyzed MgH{sub 2} in FT-IR. - Abstract: The hydrogen desorption reaction of magnesium hydride (MgH{sub 2}), MgH{sub 2} {yields} Mg + H{sub 2}, is accelerated by mixing catalytic metal oxides (e.g., Nb{sub 2}O{sub 5}). This catalytic effect is evaluated quantitatively using the atomization energy concept. The measured hydrogen desorption rate increases monotonously with increasing y x {Delta}E{sub O} values of metal oxides, M{sub x}O{sub y}. Here, {Delta}E{sub O,} is the atomization energy for the oxide ion in M{sub x}O{sub y}. This indicates that the oxide ion interacts mainly with hydrogen atom in MgH{sub 2}, in agreement with the observation of the O-H stretching mode in the FT-IR spectra during the dehydrogenation of the Nb{sub 2}O{sub 5}-catalyzed MgH{sub 2}. This approach is also proved to be useful for the catalytic analysis of metal chlorides (e.g., TiCl{sub 3}) on the decomposition reaction of NaAlH{sub 4} expressed as, NaAlH{sub 4} {yields} (1/3)Na{sub 3}AlH{sub 6} + (2/3)Al + H{sub 2}

  13. Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

    Institute of Scientific and Technical Information of China (English)

    Masoud Hasany; Mohammad Malakootikhah; Vahid Rahmanian; Soheila Yaghmaei

    2015-01-01

    A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogena-tion method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and significant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.

  14. Effect of Sodium on the Catalytic Properties of VOx/CeO2 Catalysts for Oxidative Dehydrogenation of Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Wei, Zhehao; Sun, Junming; Gao, Feng; Peden, Charles HF; Wang, Yong

    2013-03-21

    A series of VOx/CeO2 catalysts with various sodium loadings (Na/V ratio from 0 to 1) has been studied for oxidative dehydrogenation (ODH) of methanol. The effect of sodium on the surface structure, redox properties, and surface acidity/basicity of VOx/CeO2 was investigated using hydrogen temperature-programmed reduction (H2-TPR), Raman spectroscopy, and Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFT). The experimental results indicate that the effect of sodium on VOx/CeO2 is highly dependent on the Na/V ratio. At a low Na/V ratio (Na/V<0.25), sodium addition only slightly decreases the redox properties of VOx/CeO2 and has little effect on its activity and selectivity to formaldehyde, even though the Brönsted acidity is almost completely eliminated at a Na/V ratio of 0.25. At a high Na/V ratio (Na/V>0.25), sodium addition greatly alters the nature of the active sites by V-O-Ce bond cleavage and V-O-Na bond formation, leading to significantly reduced activity of the VOx/CeO2 catalysts. At Na/V>0.25, the selectivity to formaldehyde also decreases with increasing Na/V ratio due to: (1) the suppressed reducibility of VOx, and (2) increased basicity leading to increased CO2.

  15. Oxidative dehydrogenation of isobutane over a titanium pyrophosphate catalyst

    Directory of Open Access Journals (Sweden)

    IOAN-CEZAR MARCU

    2005-06-01

    Full Text Available The catalytic properties of titanium pyrophosphate in the oxidative dehydrogenation of isobutane to isobutylene were investigated in the 400 – 550 ºC temperature range. Asignificant change of the product distribution and of the apparent activation energy of the reactionwas observed at about 490 ºC. This phenomenon, already observed in the oxidative dehydrogenation of n-butane, has been interpreted by the existence of two reaction mechanisms depending upon the reaction temperature. Comparison with the n-butane reaction allowed different activation pathways for the activation of alkanes to be proposed. The catalytic properties of TiP2O7 in the oxidative dehydrogenation of isobutane was also compared to those obtained previously with several other pyrophosphates and TiP2O7 was found to be less active and selective for this reaction.

  16. Alkane dehydrogenation over supported chromium oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    The dehydrogenation of alkanes over supported chromium oxide catalysts in the absence of oxygen is of high interest for the industrial production of propene and isobutene. In this review, a critical overview is given of the current knowledge nowadays available about chromium-based dehydrogenation ca

  17. Effect of CO{sub 2}-admixture on the catalytic performance of Ni-Nb-M-O catalysts in oxidative dehydrogenation of ethane to ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, A.; Kalevaru, V.N.; Martin, A. [Rostock Univ. (Germany). Leibniz-Institut fuer Katalyse e.V.; Hari Kumar, A. Sri; Lingaiah, N.; Prasad, P.S. Sai [Indian Institute of Chemical Technology, Hyderabad (India). Inorganic and Physical Chemistry Div.

    2012-07-01

    In this work, we report the synthesis, characterization and application of Ni-Nb-M-O catalysts with different promoters (M = Cr, Mo, W) for the oxidative dehydrogenation (ODH) of ethane to ethylene. Ni:Nb:M ratio was kept at 1:0.176:0.1 (atomic ratio). The catalysts were calcined at 450 C/5h/air. Catalytic tests were carried out in a fixed bed quartz reactor in the temperature range from 300 to 450 C, with a fixed W/F (1.02 g/cm{sup 3} . s{sup -1}) but with changing mole ratios of C{sub 2}H{sub 6}:O{sub 2}:CO{sub 2}:N{sub 2} (1:0-1.4:1.4-0:2). The product analysis was made off-line using GC equipped with FID. It is evident that the CO{sub 2}-admixture to the reactant feed caused a slight decrease in the conversion of ethane but considerably improved the selectivity of ethylene. Among the three promoters of the same group applied, Cr exhibited superior performance compared to other two. This means increase in d-character of transition metal (i.e. from 3d to 5d) has shown an adverse effect on the conversion of ethane and selectivity of ethylene. (orig.)

  18. Copper oxide as efficient catalyst for oxidative dehydrogenation of alcohols with air

    DEFF Research Database (Denmark)

    Poreddy, Raju; Engelbrekt, Christian; Riisager, Anders

    2015-01-01

    The oxidative dehydrogenation of alcohols to carbonyl compounds was studied using CuO nanoparticle catalysts prepared by solution synthesis in buffered media. CuO nanoparticles synthesized in N-cyclohexyl- 3-aminopropanesulfonic acid buffer showed high catalytic activity for the oxidation of...... dehydrogenation of benzyl alcohols to be proposed. The use of CuO as an inexpensive and efficient heterogeneous catalyst under aerobic conditions provides a new noble metal-free and green reaction protocol for carbonyl compound synthesis....

  19. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    Science.gov (United States)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-08-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

  20. Highly efficient VOx/SBA-15 mesoporous catalysts for oxidative dehydrogenation of propane.

    Science.gov (United States)

    Liu, Yong-Mie; Cao, Yong; Zhu, Ka-Ke; Yan, Shi-Run; Dai, Wei-Lin; He, He-Yong; Fan, Kang-Nian

    2002-12-01

    Highly dispersed vanadia species on SBA-15 mesoporous silica have been found to exhibit a highly efficient catalytic performance for the oxidative dehydrogenation (ODH) of propane to light olefins (propene + ethylene). PMID:12478769

  1. Heterogeneous Partial (amm) Oxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    OpenAIRE

    Védrine, Jacques C.

    2016-01-01

    This paper presents an overview of heterogeneous partial (amm)oxidation and oxidative dehydrogenation (ODH) of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the " seven pillars " , and playing a determining role in catalytic properties, are considered to be, namely: isolation of acti...

  2. Effect of Oxygen Defects on the Catalytic Performance of VOx/CeO2 Catalysts for Oxidative Dehydrogenation of Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Baylon, Rebecca A.; Peden, Charles HF; Wang, Yong

    2015-05-01

    In this work, CeO2 nanocubes with controlled particle size and dominating (100) facets are synthesized as supports for VOx catalysts. Combined TEM, SEM, XRD, and Raman study reveals that the oxygen vacancy density of CeO2 supports can be tuned by tailoring the particle sizes without altering the dominating facets, where smaller particle sizes result in larger oxygen vacancy densities. At the same vanadium coverage, the VOx catalysts supported on small-sized CeO2 supports with higher oxygen defect densities exhibit promoted redox property and lower activation energy for methoxyl group decomposition, as evidenced by H2-TPR and methanol TPD study. These results further confirm that the presence of oxygen vacancies plays an important role in promoting the activity of VOx species in methanol oxidation. We gratefully acknowledge financial support from the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Part of this work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is a multiprogram national laboratory operated for the DOE by Battelle.

  3. Carbon mediated catalysis:A review on oxidative dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    De Chen; Anders Holmen; Zhijun Sui; Xinggui Zhou

    2014-01-01

    Carbon mediated catalysis has gained an increasing attention in both areas of nanocatalysis and nanomaterials. The progress in carbon nanomaterials provides many new opportunities to manip-ulate the types and properties of active sites of catalysts through manipulating structures, function-alities and properties of carbon surfaces. The present review focuses on progresses in carbon medi-ated oxidative dehydrogenation reactions of ethylbenzene, propane, and butane. The state-of-the-art of the developments of carbon mediated catalysis is discussed in terms of fundamental studies on adsorption of oxygen and hydrocarbons, reaction mechanism as well as effects of carbon nano-material structures and surface functional groups on the catalytic performance. We highlight the importance and challenges in tuning of the electron density of carbon and oxygen on carbon surfac-es for improving selectivity in oxidative dehydrogenation reactions.

  4. Influence of Vanadium Oxidation States on the Performance of V-Mg-Al Mixed-Oxide Catalysts for the Oxidative Dehydrogenation of Propane

    OpenAIRE

    Leticia Schacht; Juan Navarrete; Persi Schacht; Ramírez, Marco A.

    2010-01-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %). Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined...

  5. Microchannel apparatus and methods of conducting catalyzed oxidative dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Tonkovich, Anna Lee (Dublin, OH); Yang, Bin (Columbus, OH); Perry, Steven T. (Galloway, OH); Mazanec, Terry (Solon, OH); Arora, Ravi (New Albany, OH); Daly, Francis P. (Delaware, OH); Long, Richard (New Albany, OH); Yuschak, Thomas D. (Lewis Center, OH); Neagle, Paul W. (Westerville, OH); Glass, Amanda (Galloway, OH)

    2011-08-16

    Methods of oxidative dehydrogenation are described. Surprisingly, Pd and Au alloys of Pt have been discovered to be superior for oxidative dehydrogenation in microchannels. Methods of forming these catalysts via an electroless plating methodology are also described. An apparatus design that minimizes heat transfer to the apparatus' exterior is also described.

  6. Thin Film Models of Magnesium Orthovanadate Catalysts for Oxidative Dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    SAULT,ALLEN G.; MUDD,JASON E.; MILLER,JAMES E.; RUFFNER,JUDITH A.; RODRIGUEZ,MARK A.; TISSOT JR.,RALPH G.

    2001-03-01

    Magnesium vanadates are potentially important catalytic materials for the conversion of alkanes to alkenes via oxidative dehydrogenation. However, little is known about the active sites at which the catalytic reactions take place. It may be possible to obtain a significant increase in the catalytic efficiency if the effects of certain material properties on the surface reactions could be quantified and optimized through the use of appropriate preparation techniques. Given that surface reactivity is often dependent upon surface structure and that the atomic level structure of the active sites in these catalysts is virtually unknown, we desire thin film samples consisting of a single magnesium vanadate phase and a well defined crystallographic orientation in order to reduce complexity and simplify the study of active sites. This report describes the use of reactive RF sputter deposition to fabricate very highly oriented, stoichiometric Mg{sub 3}(VO{sub 4}){sub 2} thin films, and subsequent studies of the reactivity of these films under reaction conditions typically found during oxidative dehydrogenation. We demonstrate that the synthesis methods employed do in fact result in stoichiometric films with the desired crystallographic orientation, and that the chemical behavior of the films closely approximates that of bulk, high surface area Mg{sub 3}(VO{sub 4}){sub 2} powders. We further use these films to demonstrate the effects of oxygen vacancies on chemical behavior, demonstrate that surface composition can vary significantly under reaction conditions, and obtain the first evidence for structure sensitivity in Mg{sub 3}(VO{sub 4}){sub 2} catalysts.

  7. Mechanistic insights into the oxidative dehydrogenation of amines to nitriles in continuous flow

    DEFF Research Database (Denmark)

    Corker, Emily C.; Ruiz-Martínez, Javier; Riisager, Anders;

    2015-01-01

    The oxidative dehydrogenation of various aliphatic amines to their corresponding nitrile compounds using RuO2/Al2O3 catalysts in air was successfully applied to a continuous flow reaction. Conversions of amines (up to >99%) and yields of nitriles (up to 77%) varied depending on reaction conditions...... and the amine utilised. The presence of water was found to be important for the activity and stability of the RuO2/Al2O3 catalyst. The Hammett relationship and in situ infrared spectroscopy were applied to divulge details about the catalytic mechanism of the oxidative dehydrogenation of amines over Ru...

  8. Propane Dehydrogenation on Metal and Metal Oxide Catalysts

    NARCIS (Netherlands)

    Sattler, Jesper

    2014-01-01

    In this PhD thesis, the catalytic performance and deactivation of various propane dehydrogenation catalysts is studied. First of all, a literature study is performed, where the three most commonly used formulations, namely Pt-, CrOx- and GaOx-based catalysts are compared in terms of yield relative t

  9. Chromium oxide catalysts in the dehydrogenation of alkanes

    OpenAIRE

    Airaksinen, Sanna

    2005-01-01

    Light alkenes, such as propene and butenes, are important intermediates in the manufacture of fuel components and chemicals. The direct catalytic dehydrogenation of the corresponding alkanes is a selective way to produce these alkenes and is frequently carried out using chromia/alumina catalysts. The aim of this work was to obtain structure–activity information, which could be utilised in the optimisation of this catalytic system. The properties of chromia/alumina catalysts were investigated ...

  10. Catalytic mechanism of the dehydrogenation of ethylbenzene over Fe–Co/Mg(Al)O derived from hydrotalcites

    KAUST Repository

    Tope, Balkrishna B.

    2011-11-01

    Catalytic mechanism of ethylbenzene dehydrogenation over Fe-Co/Mg(Al)O derived from hydrotalcites has been studied based on the XAFS and XPS catalyst characterization and the FTIR measurements of adsorbed species. Fe-Co/Mg(Al)O showed synergy, whereas Fe-Ni/Mg(Al)O showed no synergy, in the dehydrogenation of ethylbenzene. Ni species were stably incorporated as Ni2+ in the regular sites in periclase and spinel structure in the Fe-Ni/Mg(Al)O. Contrarily, Co species exists as a mixture of Co3+/Co2+ in the Fe-Co/Mg(Al)O and was partially isolated from the regular sites in the structures with increasing the Co content. Co addition enhanced Lewis acidity of Fe3+ active sites by forming Fe3+-O-Co 3+/2+(1/1) bond, resulting in an increase in the activity. FTIR of ethylbenzene adsorbed on the Fe-Co/Mg(Al)O clearly showed formations of C-O bond and π-adsorbed aromatic ring. This suggests that ethylbenzene was strongly adsorbed on the Fe3+ acid sites via π-bonding and the dehydrogenation was initiated by α-H+ abstraction from ethyl group on Mg2+-O2- basic sites, followed by C-O-Mg bond formation. The α-H+ abstraction by O2-(-Mg 2+) was likely followed by β-H abstraction, leading to the formations of styrene and H2. Such catalytic mechanism by the Fe 3+ acid-O2-(-Mg2+) base couple and the Fe 3+/Fe2+ reduction-oxidation cycle was further assisted by Co3+/Co2+, leading to a good catalytic activity for the dehydrogenation of ethylbenzene. © 2011 Elsevier B.V. All rights reserved.

  11. Oxidative dehydrogenation of ethane on rare-earth oxide-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Buyevskaya, O.; Baerns, M. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

    1998-12-31

    Results on the oxidative dehydrogenation of ethane on rare-earth oxide (REO) based catalysts (Na-P-Sm-O, Sm-Sr(Ca)-O, La-Sr-O and Nd-Sr-O) are described. Oxygen adsorption was found to be a key factor which determines the activity of this type of catalysts. Continuous flow experiments in the presence of catalysts which reveal strong oxygen adsorption showed that the reaction mixture is ignited resulting in an enhanced heat generation at the reactor inlet. The heat produced by the oxidative reactions was sufficient under the conditions chosen for the endothermic thermal pyrolysis which takes place preferentially in the gas phase. Ignition of the reaction mixture is an important catalyst function. Contrary to non-catalytic oxidative dehydrogenation, reaction temperatures above 700 C could be achieved without significant external heat input. Ethylene yields of up to 34-45% (S=66-73%) were obtained on REO-based catalysts under non-isothermal conditions (T{sub max}=810-865 C) at contact times in the order of 30 to 40 ms. (orig.)

  12. Investigations of VOx/SBA-15 catalytic performance in propane dehydrogenation with CO2

    OpenAIRE

    Ze?czak, Kamila; Michorczyk, Piotr; Ogonowski, Jan

    2011-01-01

    The catalytic activity of V-containing SBA-15 materials wereprepared by incipient wetness method and tested in propane dehydrogenation with carbon dioxide. It has been found that vanadium catalysts show relatively high catalytic activity and selectivity to propene. The highest activity exhibits the sample containing 5 wt. % of V. At temperature 823 K, propane conversion and propene selectivity were 26,7%, while 70 %, respectively.

  13. Oxidative dehydrogenation of ethane to ethylene using vanadia based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Ailing; Kalevaru, V.N. [Univ. Rostock e.V., Rostock (Germany). Leibniz-Inst. fuer Katalyse; Humar, A.S.; Lingaiah, N.; Sai Prasad, P.S.; Martin, A. [Indian Institute of Chemical Technology, Hyderabad (India). Inorganic and Physical Chemistry Div.

    2011-07-01

    In this work, we describe the application of V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalysts for the oxidative dehydrogenation (ODH) of ethane to ethylene. A series of Nb{sub 2}O{sub 5} supported V{sub 2}O{sub 5} catalysts were prepared by impregnation technique. NH{sub 4}VO{sub 3} was used as a precursor for V{sub 2}O{sub 5}. The content of V{sub 2}O{sub 5} is varied in the range from 5 to 20 wt%. Catalytic tests were carried out in a fixed bed quartz reactor in the temperature range from 500 to 600 C. The conversion of ethane has been increased from ca. 20 to 35 % with increase in temperature from 500 to 600 C, while the yield of ethylene is increased from about 5 to 12 % only. CO and CO{sub 2} are the only major by-products of the reaction. The activity tests were performed at low O{sub 2} concentration in the feed and hence low conversions were achieved. Furthermore, the conversion of ethane is found to increase continuously with increase in V{sub 2}O{sub 5} loading while the yield of C{sub 2}H{sub 4} increased only up to 10wt% V{sub 2}O{sub 5} and then decreased. Results revealed that the catalytic activity and selectivity is found to depend on the V{sub 2}O{sub 5} loading. Among all, 10wt% V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalyst has displayed the superior performance. (orig.)

  14. Dynamic Structure of Mo-O Species in Ag-Mo-P-O Catalyst for Oxidative Dehydrogenation of Propane

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The dynamic structure of Mo-O species in Ag-Mo-P-O catalyst was studied by in situ confocal microprobe laser Raman spectroscopy (LRS) and catalytic test. The results indicate Mo-O species of MoO3 transformed to Mo-O species of AgMoO2PO4 in C3H8/O2/N2 (3/1/4) flow at 773 K. This behavior is closely relative to oxidative dehydrogenation of propane and intrinsic properties of Mo-O species. The Mo-O species of AgMoO2PO4 may be active species for oxidative dehydrogenation of propane.

  15. Cu, Fe, or Ni doped molybdenum oxide supported on Al2O3 for the oxidative dehydrogenation of ethylbenzene

    Institute of Scientific and Technical Information of China (English)

    Tiago Pinheiro Braga; Antônio Narcísio Pinheiro; Edson R. Leite; Regina Cláudia R. dos Santos; Antoninho Valentini

    2015-01-01

    Molybdenum-based catalysts supported on Al2O3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was sup-ported using an unconventional route that combined the polymeric precursor method (Pechini) and wet impregnation on commercial alumina. The samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, temperature-programmed reduction of H2 (H2-TPR), and thermogravimetric (TG) analysis. XRD results showed that the added metals were well dis-persed on the alumina support. The addition of the metal oxide (Ni, Cu, or Fe) of 2 wt% by wet im-pregnation did not affect the texture of the support. TPR results indicated a synergistic effect be-tween the dopant and molybdenum oxide. The catalytic tests showed ethylbenzene conversion of 28%–53% and styrene selectivity of 94%–97%, indicating that the addition of the dopant improved the catalytic performance, which was related to the redox mechanism. Molybdenum oxides play a fundamental role in the oxidative dehydrogenation of ethylbenzene to styrene by its redox and acid–base properties. The sample containing Cu showed an atypical result with increasing conver-sion during the reaction, which was due to metal reduction. The Ni-containing solid exhibited the highest amount of carbon deposited, shown by TG analysis after the catalytic test, which explained its lower catalytic stability and selectivity.

  16. Revisiting Oxidative Dehydrogenation of Ethane by W Doping into MoVMn Mixed Oxides at Low Temperature

    Directory of Open Access Journals (Sweden)

    Mohammed H. Al-Hazmi

    2015-01-01

    Full Text Available The catalytic performance of MoVMnW mixed oxides was investigated in the oxidative dehydrogenation of ethane at three different reaction temperatures (235, 255, and 275°C using oxygen as an oxidant. The catalysts were characterized by using X-ray diffraction, temperature-programmed reduction, and scanning electron microscopy. The MoVMnW mixed oxide catalyst showed the 70–90% of ethylene selectivity at the reaction temperatures. However, a significant decrease in the selectivity of ethylene was observed by increasing the reaction temperature from 235°C to 275°C.

  17. Metal oxides modified NiO catalysts for oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2014-06-01

    The sol-gel method was applied to the synthesis of Zr, Ti, Mo, W, and V modified NiO based catalysts for the ethane oxidative dehydrogenation reaction. The synthesized catalysts were characterized by XRD, N2 adsorption, SEM and TPR techniques. The results showed that the doping metals could be highly dispersed into NiO domains without the formation of large amount of other bulk metal oxide. The modified NiO materials have small particle size, larger surface area, and higher reduction temperature in contrast to pure NiO. The introduction of group IV, V and VI transition metals into NiO decreases the catalytic activity in ethane ODH. However, the ethylene selectivity is enhanced with the highest level for the Ni-W-O and Ni-Ti-O catalysts. As a result, these two catalysts show improved efficiency of ethylene production in the ethane ODH reaction. © 2014 Elsevier B.V. All rights reserved.

  18. Synthesis, spectral and catalytic dehydrogenation studies of ruthenium complexes containing NO bidentate ligands

    Science.gov (United States)

    Shoair, A. F.; El-Bindary, A. A.

    2014-10-01

    The synthesis and characterization of ruthenium mononuclear complexes containing NO bidentate ligands are reported. The complexes cis-[RuII(bpy)2L](PF6)n (1a-c), [RuIIICl(L)2(H2O)] (2a-b) and [RuIIICl2(L)2]Cl (2c) were prepared by the reaction of cis-[RuIICl2(bpy)2]·2H2O (bpy = 2,2";-bipyridine) and/or RuCl3·nH2O with the Ligands: 2-aminophenol (2-aph), 8-hydroxyquinoline (8-hq) and 4-aminoantipyrine (4-apy). These complexes were characterized by elemental analysis, spectroscopic (IR, UV-Vis, 1H NMR, ESR) and magnetic susceptibility measurements. The ligand field parameters, Δo (splitting parameter), B (Racah parameter of interelectronic repulsion), and β (nephelauxetic ratio) were calculated. The redox properties were also investigated electrochemically by cyclic voltammetry. The complexes cis-[RuII(bpy)2(8-hq)](PF6)2 (1b) and [RuIIICl(8-hq)2(H2O)] (2b) have been investigated in conjunction with N-methylmorpholine-N-oxide (NMO) as co-oxidant for the catalytic dehydrogenation of benzyl amine, p-methyl benzylamine and p-nitrobenzylamine to their respective nitriles.

  19. Chemical, Structural, and Morphological Changes of a MoVTeNb Catalyst during Oxidative Dehydrogenation of Ethane

    OpenAIRE

    Valente, Jaime S.; Armendariz-Herrera, Héctor; Quintana-Solorzano, Roberto; Del Angel, Paz; Nava, Noel; Masso Ramírez, Amada; López Nieto, José Manuel

    2014-01-01

    MoVTeNb mixed oxide, a highly active and selective catalyst for the oxidative dehydrogenation of ethane to produce ethylene, exhibits the so-called M1 and M2 crystalline phases. The thermal stability of the MoVTeNb catalytic system was assessed under varying reaction conditions; to this end, the catalyst was exposed to several reaction temperatures spanning from 440 to 550 °C. Both the pristine and spent materials were analyzed by several characterization techniques. The ...

  20. Incorporation of catalytic dehydrogenation into fischer-tropsch synthesis to significantly reduce carbon dioxide emissions

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, Gerald P.

    2012-11-13

    A new method of producing liquid transportation fuels from coal and other hydrocarbons that significantly reduces carbon dioxide emissions by combining Fischer-Tropsch synthesis with catalytic dehydrogenation is claimed. Catalytic dehydrogenation (CDH) of the gaseous products (C1-C4) of Fischer-Tropsch synthesis (FTS) can produce large quantities of hydrogen while converting the carbon to multi-walled carbon nanotubes (MWCNT). Incorporation of CDH into a FTS-CDH plant converting coal to liquid fuels can eliminate all or most of the CO.sub.2 emissions from the water-gas shift (WGS) reaction that is currently used to elevate the H.sub.2 level of coal-derived syngas for FTS. Additionally, the FTS-CDH process saves large amounts of water used by the WGS reaction and produces a valuable by-product, MWCNT.

  1. Ni–Ta–O mixed oxide catalysts for the low temperature oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2015-09-01

    The "wet" sol-gel and "dry" solid-state methods were used to prepare Ni-Ta-O mixed oxide catalysts. The resulting Ni-Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta/(Ni + Ta) atomic ratios (varying from 0 to 0.11 in "wet" sol-gel method, and from 0 to 0.20 in "dry" solid-state method) as well as the preparation methods used in the synthesis, play important roles in controlling catalyst structure, activity, selectivity and stability in the oxidative dehydrogenation of ethane. Electron microscopy characterizations (TEM, EELS mapping, and HAADF-STEM) clearly demonstrate that the Ta atoms are inserted into NiO crystal lattice, resulting in the formation of a new Ni-Ta oxide solid solution. More Ta atoms are found to be located at the lattice sites of crystal surface in sol-gel catalyst. While, a small amount of thin layer of Ta2O5 clusters are detected in solid-state catalyst. Further characterization by XRD, N2 adsorption, SEM, H2-TPR, XPS, and Raman techniques reveal different properties of these two Ni-Ta oxides. Due to the different properties of the Ni-Ta oxide catalysts prepared by two distinct approaches, they exhibit different catalytic behaviors in the ethane oxidative dehydrogenation reaction at low temperature. Thus, the catalytic performance of Ni-Ta-O mixed oxide catalysts can be systematically modified and tuned by selecting a suitable synthesis method, and then varying the Ta content. ©2015 Elsevier Inc. All rights reserved.

  2. Chemically Modified Activated Carbons as Catalysts of Oxidative Dehydrogenation of n-Butane

    International Nuclear Information System (INIS)

    Commercial availability and low price of light alkanes make them very attractive in many branches of industry. Potentially interesting is their use in the process of oxidative dehydrogenation leading to production of olefins. This study was undertaken to characterise the oxidative dehydrogenation of n-butane to 1,3-butadiene (important substrate in production of synthetic rubber and polyamides) taking place over the modified carbon catalysts obtained from peach stones precursor. The catalytic tests were performed in the temperature range 250-450oC at oxygen/n-butane ratio of 1:1. For the majority of the activated carbon samples studied at the lowest temperature the only product was CO2. At 300oC the products of dehydrogenation of n-butane and side products appeared. With increasing temperature the amount of compounds generated increased and in the group of C4 hydrocarbons the dominant were 1-butene and 1,3-butadiene. The most effective catalyst was the sample oxidised with air, the least effective was the sample modified with ammonium peroxydisulphate. (authors)

  3. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  4. Highly selective oxidative dehydrogenation of ethane with supported molten chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.A.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen (Germany). Catalysis Research Center

    2011-07-01

    Ethene production is one of the most important transformations in chemical industry, given that C{sub 2}H{sub 4} serves as building block for many mass-market products. Besides conventional thermal processes like steam cracking of ethane, ethane can be produced selectively by catalytic processes. One of the classes of catalysts that have been reported in literature as active and highly selective for the oxidative dehydrogenation of ethane is that of supported molten chloride catalysts, containing an alkali chloride overlayer on a solid support. This work deals with fundamental aspects of the catalytic action in latter class of catalysts. Results from kinetic reaction studies are related to observations in detailed characterization and lead to a comprehensive mechanistic understanding. Of fundamental importance towards mechanistic insights is the oxygen storage capacity of the catalysts that has been determined by transient step experiments. (orig.)

  5. Mo-V-Te-Nb oxides as catalysts for ethene production by oxidative dehydrogenation of ethane

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, D. [Technische Universitaet Muenchen, Garching (Germany). Dept. of Chemistry and Catalysis Research Center; Meiswinkel, A.; Thaller, C.; Bock, M.; Alvarado, L. [Linde AG, Pullach (Germany)

    2013-11-01

    The availability of ethane in shale gas, as well as the interest in valorising previously underutilized carbon feedstocks, makes the oxidative dehydrogenation (ODH) of ethane an attractive alternative to the industrially established processes for production of ethylene. Mo-V-Te-Nb mixed oxide has been chosen as catalyst for the ODH reaction in view of its outstanding ability to activate alkane molecules. Catalytic test results showed that this type of catalyst can selectively oxidize ethane to ethene at moderate temperatures (350-400 C) with minor production of CO{sub x}. The catalytic performance of Mo-V-Te-Nb mixed-oxide is mainly attributable to the crystalline phase 'M1'. Rietveld analysis of the X-Ray diffractograms allowed us to quantify the amount of MoVTeNb oxide that has crystallized as M1. In this way, it was possible to find a linear correlation of the reaction rate with the abundance of M1 in the solid. Therefore, it is clear that for improving the efficiency of MoVTeNb oxide in ODH, the amount of M1 in the catalyst should be maximized. With this purpose, several MoVTeNb oxides were subject to different thermal treatments prior to the catalytic test. Structural changes in the catalyst were monitored by in-situ XRD technique. Under oxidative atmosphere, it was observed a recrystallization of M2 and possibly, amorphous oxide, into M1 phase, leading to correspondingly more active and selective catalysts (selectivities above 95 % for ethane conversions up to 40 % under industrially relevant conditions). The active site of M1 involves V species, likely with redox properties enhanced by the proximity of Mo and Te species, while the function of the crystalline structure itself is to provide the spatial configuration that allows interaction between these species. However, ethene formation rate was observed to be independent of the V content of the samples. The vanadium species exposed at the surface were studied by LEIS and by IR spectroscopy of CO

  6. Study of the performance of vanadium based catalysts prepared by grafting in the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Santacesaria, E.; Carotenuto, G.; Tesser, R.; Di Serio, M. [Naples Univ. (Italy). Dept. of Chemistry

    2011-07-01

    The oxidative dehydrogenation (ODH) of propane has been investigated by using many different vanadia based catalysts, prepared by grafting technique and containing variable amounts of active phase supported on SiO{sub 2} previously coated, by grafting in three different steps, with multilayer of TiO{sub 2}. A depth catalytic screening, conducted in a temperature range of 400-600 C, at atmospheric pressure and in a range of residence time W/F=0.08-0.33 ghmol{sub -1}, has shown that the vanadium oxide catalysts on TiO{sub 2}-SiO{sub 2} support, prepared by grafting have good performances in the ODH of propane. In particular, a preliminary study has demonstrated that higher selectivities can be obtained employing catalysts having a well dispersed active phase that can be achieved with a V{sub 2}O{sub 5} content lower than 10%{sub w}t. It is well known that, in the case of redox catalysts, an increase of the selectivity can be achieved not only by using an adequate catalytic system but also via engineering routes like decoupling catalytic steps of reduction and re-oxidation. In fact it has been observed that by operating in dehydrogenating mode, on the same catalysts, a higher selectivity is obtained although the catalyst is poisoned by the formation of coke on the surface. As consequence of the results obtained in dehydrogenation, in this work has been explored the possibility to feed low amounts of oxygen, below the stoichiometric level with the aim to keep clean the surface from coke but maintaining high the selectivity, because, dehydrogenation reaction prevails. In this work, the behavior of catalysts containing different amounts of V2O5 has been studied in the propane-propene reaction by using different ratios C{sub 3}H{sub 8}/O{sub 2} included in the range 0-2. (orig.)

  7. Surface-Modified Carbon Nanotubes Catalyze Oxidative Dehydrogenation of n-Butane

    OpenAIRE

    J. Zhang; Liu, X; Blume, R.; Zhang, A; Schlögl, R.; Su, D.

    2008-01-01

    Butenes and butadiene, which are useful intermediates for the synthesis of polymers and other compounds, are synthesized traditionally by oxidative dehydrogenation (ODH) of n-butane over complex metal oxides. Such catalysts require high O2/butane ratios to maintain the activity, which leads to unwanted product oxidation. We show that carbon nanotubes with modified surface functionality efficiently catalyze the oxidative dehydrogenation of n-butane to butenes, especially butadiene. For low O2/...

  8. Nb effect in the nickel oxide-catalyzed low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2012-01-01

    A method for the preparation of NiO and Nb-NiO nanocomposites is developed, based on the slow oxidation of a nickel-rich Nb-Ni gel obtained in citric acid. The resulting materials have higher surface areas than those obtained by the classical evaporation method from nickel nitrate and ammonium niobium oxalate. These consist in NiO nanocrystallites (7-13 nm) associated, at Nb contents >3 at.%., with an amorphous thin layer (1-2 nm) of a niobium-rich mixed oxide with a structure similar to that of NiNb 2O 6. Unlike bulk nickel oxides, the activity of these nanooxides for low-temperature ethane oxidative dehydrogenation (ODH) has been related to their redox properties. In addition to limiting the size of NiO crystallites, the presence of the Nb-rich phase also inhibits NiO reducibility. At Nb content >5 at.%, Nb-NiO composites are thus less active for ethane ODH but more selective, indicating that the Nb-rich phase probably covers part of the unselective, non-stoichiometric, active oxygen species of NiO. This geometric effect is supported by high-resolution transmission electron microscopy observations. The close interaction between NiO and the thin Nb-rich mixed oxide layer, combined with possible restructuration of the nanocomposite under ODH conditions, leads to significant catalyst deactivation at high Nb loadings. Hence, the most efficient ODH catalysts obtained by this method are those containing 3-4 at.% Nb, which combine high activity, selectivity, and stability. The impact of the preparation method on the structural and catalytic properties of Nb-NiO nanocomposites suggests that further improvement in NiO-catalyzed ethane ODH can be expected upon optimization of the catalyst. © 2011 Elsevier Inc. All rights reserved.

  9. 铯添加对VOx/SBA-15催化剂丙烷氧化脱氢性能影响%Effect of Cesium Loading on Catalytic Activity of VOx/SBA-15 Catalysts for Propane Oxidative Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    郭建平; 伊晓东; 吴钟芳; 华卫琦; 黄传敬; 翁维正; 万惠霖

    2011-01-01

    The effect of cesium loading on the performance of single-site ( pseudotetrahedral monovanadate VO4 ) VOx/SBA-15 catalysts for propane oxidative dehydrogenation was investigated. The addition of Ce significantly improved the selectivity of propene which was enhanced by about 10% at the same propane conversions. The catalysts were characterized by XRD, Raman, H2-TPR, NH3-TPD and FT-IR spectroscopy of pyridine adsorption. The resuits indicated that the addition of a small amount of cesium did not change the structure and reducibility of active centers but resulted in a decrease of Broensted acid sites which favors propene desorption and prevents the overoxidation of propene to carbon oxides.%我们考察了碱金属铯的添加对具有单一活性中心(分立的VOx四面体)的VOx/SBA-15催化剂上丙烷氧化脱氢反应性能的影响,发现铯的加入可以显著改善丙烯的选择性.在相同的丙烷转化率时,丙烯选择性提高了约10%.对催化剂的X射线衍射,拉曼光谱,程序升温还原,吡啶吸附IR光谱和程序升温脱附表征结果表明,少量碱金属的加入,并未改变活性中心的结构及其可还原性能,但明显降低了催化剂表面酸量,尤其是B酸量,从而有利于产物丙烯的脱附,抑制了深度氧化产物COx的产生,提高了丙烯的选择性.

  10. Oxidative dehydrogenation of propane with K-MoO3/MgAl2O4 catalysts

    Indian Academy of Sciences (India)

    Serkan Naci Koc; Kubra Dayioglu; Hasan Ozdemir

    2016-01-01

    In this study, for the first time, MoO3/MgAl2O4 catalysts and their potassium-promoted forms were prepared and tested for oxidative dehydrogenation of propane. Catalysts were characterized with XRD, BET, NH3-TPD, TPR and XPS methods. Catalytic activity measurement was done with quartz microreactor between 450 and 550°C. It has been observed that the conversion of propane increased with temperature and total hydrocarbon selectivity increased with molybdenum oxide content. The acidity of catalysts decreased with potassium addition due to interaction with MoO3 sites. For this reason total hydrocarbon selectivity highly increased.

  11. In situ spectroscopic investigation of oxidative dehydrogenation and disproportionation of benzyl alcohol

    OpenAIRE

    Nowicka, E.; HOFMANN, J.P.; Parker, S. F.; Sankar, M.; Lari, G.M.; Kondrat, S.A.; Knight, D. W.; Bethell, D; Weckhuysen, B.M.; G. J. Hutchings

    2013-01-01

    In the solvent free oxidation of benzyl alcohol, using supported gold–palladium nanoalloys, toluene is often one of major by-products and it is formed by the disproportionation of benzyl alcohol. Gold–palladium catalysts on acidic supports promote both the disproportionation of benzyl alcohol and oxidative dehydrogenation to form benzaldehyde. Basic supports completely switch off disproportionation and the gold–palladium nanoparticles catalyse the oxidative dehydrogenation reaction exclusivel...

  12. Effect of catalyst structure on oxidative dehydrogenation of ethane and propane on alumina-supported vanadia

    Energy Technology Data Exchange (ETDEWEB)

    Argyle, Morris D.; Chen, Kaidong; Bell, Alexis T.; Iglesia, Enrique

    2001-09-11

    The catalytic properties of Al2O3-supported vanadia with a wide range of VOx surface density (1.4-34.2 V/nm2) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominantly as isolated monovanadate species below {approx}2.3 V/nm2. As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 V/nm2) along with increasing amounts of V2O5 crystallites at surface densities above 7.0 V/nm2. The rate constant for oxidative dehydrogenation (k1) and its ratio with alkane and alkene combustion (k2/k1 and k3/k1, respectively) were compared for both alkane reactants as a function of vanadia surface density. Propene formation rates (per V-atom) are {approx}8 times higher than ethene formation rates at a given reaction temperature, but the apparent ODH activation energies (E1) are similar for the two reactants and relatively insensitive to vanadia surface density. Ethene and propene formation rates (per V-atom) are strongly influenced by vanadia surface density and reach a maximum value at intermediate surface densities ({approx}8 V/nm2). The ratio of k2/k1 depends weakly on reaction temperature, indicating that activation energies for alkane combustion and ODH reactions are similar. The ratio of k2/k1 is independent of surface density for ethane, but increase slightly with vanadia surface density for propane, suggesting that isolated structures prevalent at low surface densities are slightly more selective for alkane dehydrogenation reactions. The ratio of k3/k1 decreases markedly with increasing reaction temperature for both ethane and propane ODH. Thus, the apparent activation energy for alkene combustion (E3) is much lower than that for alkane dehydrogenation (E1) and the difference between these two activation energies decreases with increasing surface density. The lower alkene selectivities observed at high vanadia surface densities are attributed to an

  13. Catalytic dehydrogenation of isobutane in the presence of hydrogen over Cs-modified Ni2P supported on active carbon

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Ni2P catalyst is tested in dehydrogenation of isobutane for the first time. • The effects of Cs promoter on catalytic performance of Ni2P/AC were investigated. • Cs-Ni2P/AC exhibits high activity and selectivity for isobutane dehydrogenation. - Abstract: In this article, an environmentally friendly non-noble-metal class of Cs-Ni2P/active carbon (AC) catalyst was prepared and demonstrated to exhibit enhanced catalytic performance in isobutane dehydrogenation. The results of activity tests reveal that Ni/AC catalyst was highly active for isobutane cracking, which led to the formation of abundant methane and coke. After the introduction of phosphorus through impregnation with ammonium di-hydrogen phosphate and H2-temperature programmed reduction, undesired cracking reactions were effectively inhibited, and the selectivity to isobutene and stability of catalyst increased remarkably. The characterization results indicate that, after the addition of phosphorous, the improvement of dehydrogenation selectivity is ascribed to the partial positive charges carried on Ni surface in Ni2P particles, which decreases the strength of Ni-C bond between Ni and carbonium-ion intermediates and the possibility of excessive dehydrogenation. In addition, Cs-modified Ni2P/AC catalysts display much higher catalytic performance as compared to Ni2P/AC catalyst. Cs-Ni2P-6.5 catalyst has the highest catalytic performance, and the selectivity to isobutene higher than 93% can be obtained even after 4 h reaction. The enhancement in catalytic performance of the Cs-modified catalysts is mainly attributed to the function of Cs to improve the dispersion of Ni2P particles, transfer electron from Cs to Ni, and decrease acid site number and strength

  14. Oxidative dehydrogenation of isobutyl alcohol over different structure type of zeolites

    International Nuclear Information System (INIS)

    Full text: Partial heterogen-catalytic of aliphatic alcohols is perspective method for production of important oxygen-containing compounds. Numerous of the literature data testify that the different mixed oxides of metals show the relatively high catalytic activity in the reactions of oxidation of aliphatic alcohols. Until recently however little attention had been given to the possibility of using of the modified zeolites for promoting these reactions. The present paper is devoted to oxidative dehydrogenation of isobutyl alcohol in the presence of molecular oxygen over different structure type of synthetical (A, X, Y, ZSM-5) and natural zeolites modified by cations of transition elements (Cu2+, Sn2+, Ni2+, Co2+, Fe2+ and Pd2+) for the purpose of selection of an active catalyst for production of corresponding aldehyde. For making of active catalyst on the first stage the study was carried out ever mono- and on the second stage over bimethalzeolite catalysts. It has been established that for each of zeolite has there optimum concentration of transition element cation in the dependence of structure of zeolites. It has been found that, the mono metallic catalysts on the basis of synthetical zeolites more active in this reaction than catalysts on the basis of natural zeolites. Introduction of second metal cation (Pd2+) into structure of mono metallic catalyst leaded considerable increasing of conversion of alcohol and selectivity of the process and stability of operation of catalysts

  15. VO x /SiO 2 Catalyst Prepared by Grafting VOCl 3 on Silica for Oxidative Dehydrogenation of Propane

    KAUST Repository

    Zhu, Haibo

    2015-09-07

    The VOx/SiO2 catalysts for oxidative dehydrogenation of propane were synthesized by a simple grafting method. The VOCl3 was first grafted at the surface of SiO2, which was dehydrated at different temperature (from 200 to 1000°C). The formed grafted complexes were then calcined in air, leading to the formation of VOx/SiO2 catalysts. The synthesized catalysts were characterized by nitrogen adsorption, SEM, Raman spectroscopy, temperature-programmed reduction, and extended X-ray absorption fine structure analysis. The SiO2 pretreatment temperature has an evident effect on the loading and dispersion of VOx on SiO2, which finally affects their catalytic performance. High SiO2 treatment temperature is beneficial to dispersing the vanadium oxide species at the SiO2 surface. These materials are efficient catalysts for the catalytic oxidative dehydrogenation of propane to propylene. The best selectivity to propylene is achieved on the VOx/SiO2-(1000) catalyst. The high selectivity and activity are well maintained for three days catalytic reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. A study of the isobutane dehydrogenation in a porous membrane catalytic reactor: design, use and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Casanave, D.

    1996-01-26

    The aim of this study was to set up and model a catalytic fixed-bed membrane reactor for the isobutane dehydrogenation. The catalyst, developed at Catalysis Research Institute (IRC), was a silicalite-supported Pt-based catalyst. Their catalytic performances (activity, selectivity, stability) where found better adapted to the membrane reactor, when compared with commercial Pt or Cr based catalysts. The kinetic study of the reaction has been performed in a differential reactor and led to the determination of a kinetic law, suitable when the catalyst is used near thermodynamic equilibrium. The mass transfer mechanisms were determined in meso-porous and microporous membranes through both permeability and gas mixtures (iC{sub 4}/H{sub 2}/N{sub 2}) separation measurements. For the meso-porous {gamma}-alumina, the mass transfer is ensured by a Knudsen diffusion mechanism which can compete with surface diffusion for condensable gas like isobutane. The resulting permselectivity H{sub 2}/iC4 of this membrane is low ({approx} 4). For the microporous zeolite membrane, molecular sieving occurs due to steric hindrance, leading to higher permselectivity {approx}14. Catalyst/membrane associations were compared in terms of isobutane dehydrogenation performances, for both types of membranes (meso-porous and microporous) and for two different reactor configurations (co-current and counter-current sweep gas flow). The best experimental results were obtained with the zeolite membrane, when sweeping the outer compartment in a co-current flow. The equilibrium displacement observed with the {gamma}-alumina membrane was lower and mainly due to a dilution effect of the reaction mixture by the sweep gas. A mathematical model was developed, which correctly describes all the experimental results obtained with the zeolite membrane, when the co-current mode is used. (Abstract Truncated)

  17. Surface Acidity/Basicity and Catalytic Reactivity of CeO2/γ-Al2O3 Catalysts for the Oxidative Dehydrogenation of Ethane with Carbon Dioxide to Ethylene

    Institute of Scientific and Technical Information of China (English)

    Xin Ge; Shenghua Hu; Qing Sun; Jianyi Shen

    2003-01-01

    Dehydrogenation of ethane to ethylene in CO2 was investigated over CeO2/γ-Al2O3 catalysts at 700 ℃ in a conventional flow reactor operating at atmospheric pressure. XRD, BET and microcalorimetric adsorption techniques were used to characterize the structure and surface acidity/basicity of the CeO2/γ-Al2O3 catalysts. The results show that the surface acidity decreased while the surface basicity increased after the addition of CeO2 to γ-Al2O3. Accordingly, the activity of the hydrogenation reaction of CO2 increased, which might be responsible for the enhanced conversion in the dehydrogenation of ethane to ethylene. The highest ethane conversion obtained was about 15% for the 25%CeO2/γ-Al2O3. The selectivity to ethylene was high for all the CeO2, γ-Al2O3 and CeO2/γ-Al2O3 catalysts.

  18. Catalytic effect of Ti and Ni on dehydrogenation of AlH{sub 3}: A first principles investigation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, H.Z.; Dai, J.H.; Song, Y., E-mail: sy@hitwh.edu.cn

    2015-08-30

    Graphical abstract: - Highlights: • Ni doped in bulk and on the surface of AlH{sub 3} are unfavourable comparing to Ti. • Ti and Ni prefer to substitute for Al atom in both the bulk and surface doped systems. • Ti improves the dissociation properties of AlH{sub 3} by weakening the interactions between Al and H atoms, but the catalytic effect is weaker if Ti substitutes for Al than its interstitial doping. - Abstract: Ab initio calculations were performed for the M-doped (M = Ti or Ni) AlH{sub 3} to investigate influence of dopants Ti and Ni on the dehydrogenation properties of AlH{sub 3}. It was found that Ti and Ni prefer to substitute for Al atom in both the bulk phase and the slab surface. However a large amount of energy was needed for Ni to dope into AlH{sub 3} making that Ni might not a suitable catalyst for AlH{sub 3}. Mechanisms that Ti improved the dehydrogenation properties of AlH{sub 3} were clarified. Ti greatly decreased the dehydrogenation energy of AlH{sub 3} by weakening the interaction between Al and H atoms, its influence on the dehydrogenation of AlH3 was however sensitive to the occupation behavior. The calculations indicated that the catalytic effect of Ti was weaker if Ti substitutes for Al than its interstitial occupation.

  19. Facile synthesis of TiN decorated graphene and its enhanced catalytic effects on dehydrogenation performance of magnesium hydride.

    Science.gov (United States)

    Wang, Ying; Li, Li; An, Cuihua; Wang, Yijing; Chen, Chengcheng; Jiao, Lifang; Yuan, Huatang

    2014-06-21

    TiN@rGO nanohybrids were successfully synthesized by a simple "urea glass" technique. Experimental results demonstrated that TiN nanocrystals, with an average particle size of 20 nm, were uniformly anchored onto highly reduced graphene nanosheets. The as-synthesized TiN@rGO nanohybrids showed a porous planar-like structure, which had a large surface area of 177 m(2) g(-1). More importantly, the as-prepared TiN@rGO hybrids showed enhanced catalytic effects on the dehydrogenation of MgH2. The dehydrogenation thermodynamics and kinetics of the MgH2-TiN@rGO composites were systematically investigated and some significant improvements were confirmed. It was found that the 10 wt% TiN@rGO doped MgH2 sample started to release hydrogen at about 167 °C, and roughly 6.0 wt% hydrogen was released within 18 min when isothermally heated to 300 °C. In contrast, the onset dehydrogenation temperature of the pure MgH2 sample was about 307 °C, and only 3.5 wt% hydrogen was released even after 120 min of heating under identical conditions. In addition, the catalytic mechanism of TiN@rGO on the dehydrogenation of MgH2 was discussed using the Johnson-Mehl-Avrami (JMA) model and X-ray diffraction equipment. PMID:24817573

  20. Catalytic effect of Ti and Ni on dehydrogenation of AlH3: A first principles investigation

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Ni doped in bulk and on the surface of AlH3 are unfavourable comparing to Ti. • Ti and Ni prefer to substitute for Al atom in both the bulk and surface doped systems. • Ti improves the dissociation properties of AlH3 by weakening the interactions between Al and H atoms, but the catalytic effect is weaker if Ti substitutes for Al than its interstitial doping. - Abstract: Ab initio calculations were performed for the M-doped (M = Ti or Ni) AlH3 to investigate influence of dopants Ti and Ni on the dehydrogenation properties of AlH3. It was found that Ti and Ni prefer to substitute for Al atom in both the bulk phase and the slab surface. However a large amount of energy was needed for Ni to dope into AlH3 making that Ni might not a suitable catalyst for AlH3. Mechanisms that Ti improved the dehydrogenation properties of AlH3 were clarified. Ti greatly decreased the dehydrogenation energy of AlH3 by weakening the interaction between Al and H atoms, its influence on the dehydrogenation of AlH3 was however sensitive to the occupation behavior. The calculations indicated that the catalytic effect of Ti was weaker if Ti substitutes for Al than its interstitial occupation

  1. Ceria-Based Mixed Oxide Supported Nano-Gold as an Efficient and Durable Heterogeneous Catalyst for Oxidative Dehydrogenation of Amines to Imines Using Molecular Oxygen

    Directory of Open Access Journals (Sweden)

    Bashir Ahmad Dar

    2012-06-01

    Full Text Available The present work is intended to determine the catalytic activity of Mixed Oxide supported gold for aerobic oxidative dehydrogenation of amines to imines using Ceria as a main constituent of the each support. The model catalysts Au/CeO2:TiO2 Au/CeO2:SiO2, Au/CeO2:ZrO2 and Au/CeO2:Al2Os were prepared by deposition co-precipitation method and deposition of gold was determined by EDEX analysis. The supported nano-gold catalyzes the dehydrogenation of secondary amines to imines without loss of activity. On recycling good amount of product yield is obtained. Oxidation of secondary amines to imines is carried at 100˚C and almost 90 % conversion was obtained with >99% selectivity. © 2012 BCREC UNDIP. All rights reservedReceived: 26th December 2011; Revised: 7th June 2012; Accepted: 13rd June 2012[How to Cite: B.A. Dar, M. Sharma, B. Singh. (2012. Ceria-Based Mixed Oxide Supported Nano-Gold as an Efficient and Durable Heterogeneous Catalyst for Oxidative Dehydrogenation of Amines to Imines Using Molecular Oxygen. Bulletin of Chemical Reaction Engineering & Catalysis, 7(1: 79-84.  doi:10.9767/bcrec.7.1.1257.79-84][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1257.79-84 ] | View in 

  2. Microcalorimetric Adsorption of Alumina Oxide Catalysts for Combination of Ethylbenzene dehydrogenation and carbon Dioxide Shift-reaction

    Institute of Scientific and Technical Information of China (English)

    GE Xin; SHEN Jian-yi

    2004-01-01

    Styrene (STY) is now produced industrially in fairly large quantities by the dehydrogenation of ethylbenzene (EB) using promoted iron oxide catalyst with superheated steam.In this case, small amount of carbon dioxide formed as a by-product was known to inhibit the catalytic activity of commercial catalyst. Recently, there have been some reports which carbon dioxide showed positive effects to promote catalytic activities on the reaction over several catalysts.In this study, we attempted to combine the dehydrogenation of EB to STY with the carbon dioxide shift-reaction. The combine reaction (EB + CO2 → STY + H2O + CO) can be considered as one of the ways of using CO2 resources and can yield simultaneously STY and Carbon oxide.Alumina oxide catalysts such as Al2O3, Na2O/Al2O3 and K2O/Al2O3 were prepared by the usual impregnation method with an aqueous solution of NaNO3 and KNO3, and then calcined at 650℃ for 5 h in a stream of air. The reaction condition is 600℃, flow of CO2 38ml/mon and space velocity (EB) 1.28h-1.

  3. Catalytic ammonia oxidation to nitrogen (I) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

    The process of synthesis of nitrous oxide by low-temperature catalytical oxidation of NH has been investigated for organic synthesis. The investigation has been carried out by the stage separation approach with NH oxidation occurring in several reaction zones, which characterized by different catalytic conditions. The selectivity for N₂O was 92–92,5 % at the ammonia conversion of 98–99.5 % in the optimal temperature range.

  4. Active coke: Carbonaceous materials as catalysts for alkane dehydrogenation

    OpenAIRE

    McGregor, J.; Huang, Z; Parrott, E.; Zeitler, J.; Nguyen, K.; Rawson, J.; Carley, A; Hansen, T.; Tessonnier, J.; Su, D.; Teschner, D; Vass, E.; Knop-Gericke, A.; Schlögl, R.; Gladden, L.

    2010-01-01

    The catalytic dehydrogenation (DH) and oxidative dehydrogenation (ODH) of light alkanes are of significant industrial importance. In this work both carbonaceous materials deposited on VOx/Al2O3 catalysts during reaction and unsupported carbon nanofibres (CNFs) are shown to be active for the dehydrogenation of butane in the absence of gas-phase oxygen. Their activity in these reactions is shown to be dependent upon their structure, with different reaction temperatures yielding structurally dif...

  5. OXIDATIVE DEHYDROGENATION OF PROPANE BY RARE EARTH PHOSPHATES SUPPORTED ON AL-PILC

    Directory of Open Access Journals (Sweden)

    Carolina De Los Santos

    2012-12-01

    Full Text Available Catalytic activity in propane oxidative dehydrogenation of rare earth phosphates LnPO4 (where Ln = La, Ce, Pr, Nd, Sm and of the same supported by an aluminum pillared clay, of high specific surface area, is presented. The solids were characterized by TGA, XRD, nitrogen adsorption and immediate analysis after reaction in order to determine eventual carbon formation. Catalytic assays were performed at temperatures in the range 400oC-600oC, the reaction mixture was C3H8/O2/Ar = 10/10/80. All the catalysts were active. The reaction products were H2, CO, CO2, CH4, C2H4 and C3H6 and there were no organic oxygenated compounds detected. Although all the investigated systems were active, the Al-PILC supported catalysts presented a higher activity than the bulk materials. In this context, the samarium supported catalyst showed a propene yield increase from 4% to 10% compared with bulk samarium phosphate at 600°C. This effect was attributed to the increase in the specific surface area.

  6. Incorporation of catalytic dehydrogenation into Fischer-Tropsch synthesis to lower carbon dioxide emissions

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, Gerald P

    2012-09-18

    A method for producing liquid fuels includes the steps of gasifying a starting material selected from a group consisting of coal, biomass, carbon nanotubes and mixtures thereof to produce a syngas, subjecting that syngas to Fischer-Tropsch synthesis (FTS) to produce a hyrdrocarbon product stream, separating that hydrocarbon product stream into C1-C4 hydrocarbons and C5+ hydrocarbons to be used as liquid fuels and subjecting the C1-C4 hydrocarbons to catalytic dehydrogenation (CDH) to produce hydrogen and carbon nanotubes. The hydrogen produced by CDH is recycled to be mixed with the syngas incident to the FTS reactor in order to raise the hydrogen to carbon monoxide ratio of the syngas to values of 2 or higher, which is required to produce liquid hydrocarbon fuels. This is accomplished with little or no production of carbon dioxide, a greenhouse gas. The carbon is captured in the form of a potentially valuable by-product, multi-walled carbon nanotubes (MWNT), while huge emissions of carbon dioxide are avoided and very large quantities of water employed for the water-gas shift in traditional FTS systems are saved.

  7. Silylesterification of oxidized multi-wall carbon nanotubes by catalyzed dehydrogenative cross-coupling between carboxylic and hydrosilane functions

    Science.gov (United States)

    Seffer, J.-F.; Detriche, S.; Nagy, J. B.; Delhalle, J.; Mekhalif, Z.

    2014-06-01

    Surface modification of oxidized carbon nanotubes (O-CNTs) with silicon based anchoring groups (R-SiR3) is a relatively uncommon approach of the CNTs functionalization. Hydrosilane derivatives constitute an attractive subclass of compounds for silanization reactions on the CNTs surface. In this work, we report on the ZnCl2 catalytically controlled reaction (hydrosilane dehydrogenative cross-coupling, DHCC) of fluorinated hydrosilane probes with the carboxylic functions present on the surface of oxidized multi-wall carbon nanotubes. Carbon nanotubes functionalized with essentially alcohol groups are also used to compare the selectivity of zinc chloride toward carboxylic groups. To assess the efficiency of functionalization, X-ray Photoelectron Spectroscopy is used to determine the qualitative and quantitative composition of the different samples. Solubility tests on the oxidized and silanized MWNTs are also carried out in the framework of the Hansen Solubility Parameters (HSP) theory to apprehend at another scale the effect of DHCC.

  8. Dehydrogenative Aromatization of Saturated Aromatic Compounds by Graphite Oxide and Molecular Sieves

    Institute of Scientific and Technical Information of China (English)

    张轩; 徐亮; 王希涛; 马宁; 孙菲菲

    2012-01-01

    Graphite oxide (GO) has attracted much attention of material and catalysis chemists recently. Here we describe a combination of GO and molecular sieves for the dehydrogenative aromatization. GO prepared through improved Hummers method showed high oxidative activity in this reaction. Partially or fully saturated aromatic compounds were converted to their corresponding dehydrogenated aromatic products with fair to excellent conversions and selectivities. As both GO and molecular sieves are easily available, cheap, lowly toxic and have good tolerance to various functional groups, this reaction provides a facile approach toward aromatic compounds from their saturated precursors

  9. Environmentally benign synthesis of amides and ureas via catalytic dehydrogenation coupling of volatile alcohols and amines in a Pd-Ag membrane reactor

    KAUST Repository

    Chen, Tao

    2016-05-31

    In this study, we report the direct synthesis of amides and ureas via the catalytic dehydrogenation of volatile alcohols and amines using the Milstein catalyst in a Pd-Ag/ceramic membrane reactor. A series of amides and ureas, which could not be synthesized in an open system by catalytic dehydrogenation coupling, were obtained in moderate to high yields via catalytic dehydrogenation of volatile alcohols and amines. This process could be monitored by the hydrogen produced. Compared to the traditional method of condensation, this catalytic system avoids the stoichiometric pre-activation or in situ activation of reagents, and is a much cleaner process with high atom economy. This methodology, only possible by employing the Pd-Ag/ceramic membrane reactor, not only provides a new environmentally benign synthetic approach of amides and ureas, but is also a potential method for hydrogen storage.

  10. Highly Ordered Mesoporous Metal Oxides as Catalysts for Dehydrogenation of Cyclohexanol

    International Nuclear Information System (INIS)

    Cyclohexanone is important intermediate for the manufacture of caprolactam which is monomer of nylron. Cyclohexanone is generally produced by dehydrogenation reaction of cyclohexanol. In this study, highly mesoporous metal oxides such as meso-WO3, meso-TiO2, meso-Fe2O3, meso-CuO, meso-SnO2 and meso-NiO were synthesized using mesoporous silica KIT-6 as a hard template via nano-replication method for dehydrogenation of cyclohexanol. The overall conversion of cyclohexanol followed a general order: meso-WO3 >> meso-Fe2O3 > meso-SnO2 > meso-TiO2 > meso-NiO > meso-CuO. In particular, meso-WO3 significantly showed higher activity than the other mesoporous metal oxides. Therefore, the meso-WO3 has wide range of application possibilities for dehydrogenation of cyclohexanol

  11. Combined oxidative and non-oxidative dehydrogenation of n-butane over VOX species supported on HMS

    OpenAIRE

    Setnička, Michal; Čičmanec, Pavel; Tvarůžková, Eva; Bulánek, Roman

    2013-01-01

    The combination of oxidative and non-oxidative dehydrogenation of n-butane as an attractive possibility for production of C4 olefins was studied over VOX based catalyst. Long-term activity and selectivity to desired products could be achieved over the catalysts with well dispersed monomeric vanadium oxide species supported on mesoporous silica support.

  12. Solid State, Surface and Catalytic Studies of Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kung, H. H.

    2004-11-23

    This project investigates the catalytic properties of oxides for the selective oxidative dehydrogenation of light alkanes and for hydrocarbon reduction of NO{sub x}. Various vanadium oxide based catalysts were investigated to elucidate the relationship between the chemical and structural properties of the catalysts and their selectivity for the formation of alkenes. It was found that vanadium oxide units that are less reducible give higher selectivities. For hydrocarbon reduction of NO{sub x}, it was found that alumina-based catalysts can be effective at higher temperatures than the corresponding zeolite-based catalysts. On some catalysts, such as SnO{sub 2}/Al{sub 2}O{sub 3}. Ag/Al{sub 2}O{sub 3}, the alumina participates directly in the reaction, making the catalyst bifunctional. These results are useful in research to improve the performance of this stress of catalysts.

  13. Study on the structure, acidic properties of V–Zr nanocrystal catalysts in oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shu; Ma, Fei; Xu, Aixin [Institute of Catalysis, Zhejiang University (Xixi Campus), Hangzhou 310028 (China); Wang, Lina [Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-tech University), Hangzhou 310012 (China); Chen, Fang [Institute of Catalysis, Zhejiang University (Xixi Campus), Hangzhou 310028 (China); Lu, Weimin, E-mail: luweimin@zju.edu.cn [Institute of Catalysis, Zhejiang University (Xixi Campus), Hangzhou 310028 (China)

    2014-01-15

    A series of V-doped zirconia nanocrystal (the molar ratio of V/Zr varying from 0.001 to 0.15) were prepared via hydrothermal method and performed in oxidative dehydrogenation of propane. It was found that vanadium was highly dispersed on the surface and in the bulk of ZrO{sub 2}. The distribution of the vanadium species, the valence states and the aggregation state of V species on the surface, as well as the acid properties of the catalysts including kinds, number and strength were detected by the various characteristic methods. The correlation between the V content and the surroundings of the different V species has been studied. The function of acid properties, especially Brønsted acid in the catalytic performance has been discussed. Oxidative dehydrogenation reactions were carried out in a continuous flow fixed bed reactor and ZrV{sub 0.01} catalyst showed good conversion and selectivity with a yield of propylene of 21.3%.

  14. Study on the structure, acidic properties of V-Zr nanocrystal catalysts in oxidative dehydrogenation of propane

    Science.gov (United States)

    Chen, Shu; Ma, Fei; Xu, Aixin; Wang, Lina; Chen, Fang; Lu, Weimin

    2014-01-01

    A series of V-doped zirconia nanocrystal (the molar ratio of V/Zr varying from 0.001 to 0.15) were prepared via hydrothermal method and performed in oxidative dehydrogenation of propane. It was found that vanadium was highly dispersed on the surface and in the bulk of ZrO2. The distribution of the vanadium species, the valence states and the aggregation state of V species on the surface, as well as the acid properties of the catalysts including kinds, number and strength were detected by the various characteristic methods. The correlation between the V content and the surroundings of the different V species has been studied. The function of acid properties, especially Brønsted acid in the catalytic performance has been discussed. Oxidative dehydrogenation reactions were carried out in a continuous flow fixed bed reactor and ZrV0.01 catalyst showed good conversion and selectivity with a yield of propylene of 21.3%.

  15. Catalytic B-N Dehydrogenation Using Frustrated Lewis Pairs: Evidence for a Chain-Growth Coupling Mechanism.

    Science.gov (United States)

    Mo, Zhenbo; Rit, Arnab; Campos, Jesús; Kolychev, Eugene L; Aldridge, Simon

    2016-03-16

    The catalytic dehydrogenation of ammonia- and amine-boranes by a dimethylxanthene-derived frustrated Lewis pair is described. Turnover is facilitated on a thermodynamic basis by the ready release of H2 from the weakly basic PPh2-containing system. In situ NMR studies and the isolation of intermediates from stoichiometric reactions support a mechanism initiated by B-H activation, followed by end-growth BN coupling involving the terminal NH bond of the bound BN fragment and a BH bond of the incoming borane monomer. PMID:26918906

  16. Study of vanadium based mesoporous silicas for oxidative dehydrogenation of propane and n-butane

    Czech Academy of Sciences Publication Activity Database

    Bulánek, R.; Kalužová, A.; Setnička, M.; Zukal, Arnošt; Čičmanec, P.; Mayerová, Jana

    2012-01-01

    Roč. 179, č. 1 (2012), s. 149-158. ISSN 0920-5861 R&D Projects: GA ČR GAP106/10/0196 Institutional research plan: CEZ:AV0Z40400503 Keywords : vanadium * oxidative dehydrogenation * mesoporous silicas Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012

  17. Structure of alumina supported vanadia catalysts for oxidative dehydrogenation of propane prepared by flame spray pyrolysis

    DEFF Research Database (Denmark)

    Høj, Martin; Jensen, Anker Degn; Grunwaldt, Jan-Dierk

    2013-01-01

    A series of five vanadia on alumina catalysts for oxidative dehydrogenation of propane to propene were synthesized by flame spray pyrolysis (FSP) using vanadium(III)acetylacetonate and aluminium(III)acetylacetonate dissolved in toluene as precursors. The vanadium loading was 2, 3, 5, 7.5 and 10wt...

  18. Oxidative dehydrogenation of ethylbenzene to styrene over alumina : effect of calcination

    NARCIS (Netherlands)

    Nederlof, Christian; Zarubina, Valeriya; Melian-Cabrera, Ignacio; Heeres, Hero Jan (Eric); Kapteijn, Freek; Makkee, Michiel

    2013-01-01

    Commercially available gamma-Al2O3 was calcined at temperatures between 500 and 1200 degrees C and tested for its performance in the oxidative ethylbenzene dehydrogenation (ODH) over a wide range of industrially-relevant conditions. The original gamma-Al2O3, as well as Z- and alpha-Al2O3, were teste

  19. Development of packed bed membrane reactor for the oxidative dehydrogenation of propane

    NARCIS (Netherlands)

    Kotanjac, Zeljko

    2009-01-01

    In this research, a reactor concept for the oxidative dehydrogenation of propane was studied. First a literature survey was performed, to investigate which are the best catalyst systems and best operating conditions that result in the largest propylene yield. In the kinetic study of ODHP over a Ga2O

  20. V{sub 2}O{sub 5}-ZrO{sub 2} catalysts for the oxidative dehydrogenation of propane - influence of the niobium oxide doping

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, S.; Hallmeier, K.H.; Wendt, G. [Leipzig Univ. (Germany). Fakultaet fuer Chemie und Mineralogie; Lippold, G. [Leipzig Univ. (Germany). Fakultaet fuer Physik und Geowissenschaften

    1998-12-31

    The oxidative dehydrogenation (ODH) of light alkanes is an alternative way for the production of olefins. A wide variety of catalytic systems has been investigated. Vanadium oxide based catalysts were described in the literature as effective catalysts for the ODH of propane. The catalytic activity and selectivity depend on the kind of support material, the kind of dopants and the formation of complex metal oxide phases. In recent papers it was claimed that both orthovanadate and/or pyrovanadate species are selective for the ODH of propane. Niobia based materials were investigated as catalysts for acidic and selective oxidation type reactions. In the ODH of propane niobia exhibited a high selectivity to propene but the conversion of propane was low. V{sub 2}O{sub 5}-Nb{sub 2}O{sub 5} catalysts proved to be catalytically active and selective and showed no formation of oxygenates. In the present study the influence of the niobia dopant of the catalytic properties of V{sub 2}O{sub 5}-ZrO{sub 2} catalysts in the ODH of propane was examined. The structural and textural properties of the catalysts were investigated using several methods. (orig.)

  1. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  2. Catalytic synthesis of 2-methylpyrazine over Cr-promoted copper based catalyst via a cyclo-dehydrogenation reaction route

    Indian Academy of Sciences (India)

    Fangli Jing; Yuanyuan Zhang; Shizhong Luo; Wei Chu; Hui Zhang; Xinyu Shi

    2010-07-01

    The cyclo-dehydrogenation of ethylene diamine and propylene glycol to 2-methylpyrazine was performed under the atmospheric conditions at 380°C. The Cr-promoted Cu-Zn/Al2O3 catalysts were prepared by impregnation method and characterized by ICP-AES, N2 adsorption/desorption, XRD, XPS, N2O chemisorption, TPR and NH3-TPD techniques. The amorphous chromium species existing in Cu-Zn-Cr/Al2O3 catalyst enhanced the dispersion of active component Cu, promoted the reduction of catalyst. Furthermore, the catalytic performance was significantly improved. The acidity of the catalyst played an important role in increasing the 2-MP selectivity. To optimize the reaction parameters, influences of different chromium content, reaction temperature, liquid hourly space velocity (LHSV), reactants molar ratio and time on stream on the product pattern were studied. The results demonstrated that addition of chromium promoter revealed satisfying catalytic activity, stability and selectivity of 2-methylpyrazine.

  3. Vanadium Oxide Supported on MSU-1 as a Highly Active Catalyst for Dehydrogenation of Isobutane with CO2

    Directory of Open Access Journals (Sweden)

    Guosong Sun

    2016-03-01

    Full Text Available Vanadium oxide supported on MSU-1, with VOx loading ranging from 2.5 to 17.5 wt. %, was developed as a highly active catalyst in dehydrogenation of isobutane with CO2. The obtained catalysts of VOx/MSU-1 were characterized by X-ray diffraction (XRD, N2 adsorption-desorption, and H2-temperature programmed reduction (H2-TPR methods and the results showed that the large surface area of MSU-1 was favorable for the dispersion of VOx species and the optimal loading of VOx was 12.0 wt. %. Meanwhile, the catalytic activity of VOx/MSU-1 was investigated, and VOx/MSU-1 with 12.0 wt. % VOx content was found to be the best one, with the conversion of isobutane (58.8% and the selectivity of isobutene (78.5% under the optimal reaction conditions. In contrast with the reaction in the absence of CO2, the presence of CO2 in the reaction stream could obviously enhance the isobutane dehydrogenation, which raised the conversion of reaction and the stability of VOx/MSU-1.

  4. Influence of promoters and oxidants on propane dehydrogenation over chromium-oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Shaporeva, N.Yu.; Trushin, D.V.; Gaidai, N.A.; Nekrasov, N.V. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Inst. of Organic Chemistry

    2010-12-30

    Possibilities for increasing the efficiency of supported on SiO{sub 2} chromium-oxide catalysts in propane oxidative dehydrogenation in CO{sub 2} presence are investigated: the introduction of Li, Na, K, Ca in catalysts and the addition of O{sub 2} in the reaction mixture. It was been found that the positive role of K - the increase of the selectivity to propene and stability of catalysts at long-duration tests - appeared at the relation of Cr:K=20. It was shown that the presence of little amount of O{sub 2} (2%) in the reaction mixtures of propane and carbon dioxide resulted in the increase of propene yield and catalyst stability. (orig.)

  5. Green synthesis of Ni-Nb oxide catalysts for low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2015-03-05

    The straightforward solid-state grinding of a mixture of Ni nitrate and Nb oxalate crystals led to, after mild calcination (T<400°C), nanostructured Ni-Nb oxide composites. These new materials efficiently catalyzed the oxidative dehydrogenation (ODH) of ethane to ethylene at a relatively low temperature (T<300°C). These catalysts appear to be much more stable than the corresponding composites prepared by other chemical methods; more than 90% of their original intrinsic activity was retained after 50h with time on-stream. Furthermore, the stability was much less affected by the Nb content than in composites prepared by classical "wet" syntheses. These materials, obtained in a solvent-free way, are thus promising green and sustainable alternatives to the current Ni-Nb candidates for the low-temperature ODH of ethane.

  6. The oxidative coupling of methane and the oxidative dehydrogenation of ethane over a niobium promoted lithium doped magnesium oxide catalyst

    OpenAIRE

    Swaan, H.M.; Li, X.; Seshan, K.; Ommen, van, B.; Ross, J.R.H.

    1993-01-01

    The promoting effect of niobium in a Li/MgO catalyst for the oxidative coupling of methane (OCM) and for the oxidative dehydrogenation of ethane (ODHE) has been studied in some detail. It has been found that a Li/Nb/MgO catalyst with 16 wt % niobium showed the highest activity for the C2 production in the OCM reaction; the activity at 600 °C was ten times that of the Li/MgO catalyst at the same temperature. The Li/Nb/MgO catalyst was also slightly more active for the ODHE reaction than was th...

  7. Kinetics of Oxidative Dehydrogenation of Propance over a VMgO Catalyst

    Institute of Scientific and Technical Information of China (English)

    L.Late; E.A.Blekkan

    2002-01-01

    The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃ over a VMgO catalyst,Vanadium-magnesium-oxides are among the moste selective and active catalysts for the dehydrogenation of propance to propylene Selectivity to propylene up to about 60% was obtained at 10% conversion ,but the selectivity decreased with increasing conversion.No oxygenates were detected,the only by-products were CO and CO2 ,The reaction rate of propane was found to be first order in propane and close to zero order in oxygen ,which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate detemining step.The activation energy,of the conversion of propane was found to be 122±6 kJ/mol.

  8. Kinetics of the Oxidative Dehydrogenation of Propane over a VMgO Catalyst

    Institute of Scientific and Technical Information of China (English)

    L. L(a)te; E.A. Blekkan

    2002-01-01

    The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts forthe dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, theonly by-products were CO and CO2. The reaction rate of propane was found to be first order in propaneand close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with theactivation of the hydrocarbon as the rate determining step. The activation energy of the conversion ofpropane was found to be 122±6 kJ/mol.

  9. Catalytic Chemistry on Oxide Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Asthagiri, Aravind; Dixon, David A.; Dohnalek, Zdenek; Kay, Bruce D.; Rodriquez, Jose A.; Rousseau, Roger J.; Stacchiola, Dario; Weaver, Jason F.

    2016-05-29

    Metal oxides represent one of the most important and widely employed materials in catalysis. Extreme variability of their chemistry provides a unique opportunity to tune their properties and to utilize them for the design of highly active and selective catalysts. For bulk oxides, this can be achieved by varying their stoichiometry, phase, exposed surface facets, defect, dopant densities and numerous other ways. Further, distinct properties from those of bulk oxides can be attained by restricting the oxide dimensionality and preparing them in the form of ultrathin films and nanoclusters as discussed throughout this book. In this chapter we focus on demonstrating such unique catalytic properties brought by the oxide nanoscaling. In the highlighted studies planar models are carefully designed to achieve minimal dispersion of structural motifs and to attain detailed mechanistic understanding of targeted chemical transformations. Detailed level of morphological and structural characterization necessary to achieve this goal is accomplished by employing both high-resolution imaging via scanning probe methods and ensemble-averaged surface sensitive spectroscopic methods. Three prototypical examples illustrating different properties of nanoscaled oxides in different classes of reactions are selected.

  10. Heterogeneous Rhodium-Catalyzed Aerobic Oxidative Dehydrogenative Cross-Coupling: Nonsymmetrical Biaryl Amines.

    Science.gov (United States)

    Matsumoto, Kenji; Yoshida, Masahiro; Shindo, Mitsuru

    2016-04-18

    The first heterogeneously catalyzed oxidative dehydrogenative cross-coupling of aryl amines is reported herein. 2-Naphthylamine analogues were reacted with various electron-rich arenes using a heterogeneous Rh/C catalyst under mild aerobic conditions, thus affording nonsymmetrical biaryl amines in excellent yields with high selectivities. This reaction provides a mild, operationally simple, and efficient approach for the synthesis of biaryls which are important to pharmaceutical and materials chemistry. PMID:26996772

  11. Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

    Directory of Open Access Journals (Sweden)

    Ryo eWatanabe

    2013-10-01

    Full Text Available For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1–xSrxFeyMn1–yO3–d(0 ≤ x≤ 1, 0.2 ≤ y≤ 0.8, perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst with that of an industrial potassium promoted iron (Fe–K catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst showed higher initial activity than the industrial Fe–K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe–K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3–d and the Fe–K catalysts in aH2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst while the Fe–K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst had higher potential for activating the steam than the Fe–K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3–d was superior to that of Fe–K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3–d perovskite oxide.

  12. Catalytic dehydrogenation of isobutane in the presence of hydrogen over Cs-modified Ni{sub 2}P supported on active carbon

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yanli [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science and Technology, College of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Sang, Huanxin [Tianjin Academy of Environmental Sciences, Tianjin 300191 (China); Wang, Kang [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science and Technology, College of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Wang, Xitao, E-mail: wangxt@tju.edu.cn [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science and Technology, College of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2014-10-15

    Graphical abstract: - Highlights: • Ni{sub 2}P catalyst is tested in dehydrogenation of isobutane for the first time. • The effects of Cs promoter on catalytic performance of Ni2P/AC were investigated. • Cs-Ni2P/AC exhibits high activity and selectivity for isobutane dehydrogenation. - Abstract: In this article, an environmentally friendly non-noble-metal class of Cs-Ni{sub 2}P/active carbon (AC) catalyst was prepared and demonstrated to exhibit enhanced catalytic performance in isobutane dehydrogenation. The results of activity tests reveal that Ni/AC catalyst was highly active for isobutane cracking, which led to the formation of abundant methane and coke. After the introduction of phosphorus through impregnation with ammonium di-hydrogen phosphate and H{sub 2}-temperature programmed reduction, undesired cracking reactions were effectively inhibited, and the selectivity to isobutene and stability of catalyst increased remarkably. The characterization results indicate that, after the addition of phosphorous, the improvement of dehydrogenation selectivity is ascribed to the partial positive charges carried on Ni surface in Ni{sub 2}P particles, which decreases the strength of Ni-C bond between Ni and carbonium-ion intermediates and the possibility of excessive dehydrogenation. In addition, Cs-modified Ni{sub 2}P/AC catalysts display much higher catalytic performance as compared to Ni{sub 2}P/AC catalyst. Cs-Ni{sub 2}P-6.5 catalyst has the highest catalytic performance, and the selectivity to isobutene higher than 93% can be obtained even after 4 h reaction. The enhancement in catalytic performance of the Cs-modified catalysts is mainly attributed to the function of Cs to improve the dispersion of Ni{sub 2}P particles, transfer electron from Cs to Ni, and decrease acid site number and strength.

  13. Oxidative Dehydrogenation of Methanol on Chromium Oxide/Montmorillonite K10 Catalysts

    International Nuclear Information System (INIS)

    Methanol conversion was carried out on one of meso porous materials, Chromia I Montmorillonite K10 (MK10) in a pulse micro catalytic system. Methanol was converted to formaldehyde and ethylene by two different mechanisms. Methanol dehydrogenation increases by reaction temperature (300-400 degree C) and as chromia loading decrease. In contradiction, the dehydration of methanol takes place at higher temperature (400-500 degree C) and as chromia loading increase, 3-18% Cr. Redox and exposed non-redox Cr3+ are responsible for HCHO formation. There is relationship between increasing of C2H4 production and the increase of Cr+6 phase (from TPR and UV-Vis) according to the acidity of chromia catalysts 34 and 76 μL tert-Butylamine /gram catalyst for 3% Cr and 18% Cr, respectively. Formaldehyde formation is diffusional controlled at high temperature (400-500 degree C) and kinetically controlled at lower reaction temperature (300-400 degree C) while methanol dehydration to ethylene is surface reaction controlled at 400-500 degree C

  14. Studies on ethylbenzene dehydrogenation with CO2 as soft oxidant over Co3O4/COK-12 catalysts

    Indian Academy of Sciences (India)

    Ramudu Pochamoni; Anand Narani; Mohan Varkolu; Murali Dhar Gudimella; S Sai Prasad Potharaju; David Raju Burri; Seetha Rama Rao Kamaraju

    2015-04-01

    Oxidative dehydrogenation of ethylbenzene to styrene has been studied over Co3O4 supported on mesoporous silica (COK-12) with CO2 as soft oxidant in a fixed bed reactor at atmospheric pressure in the temperature range of 723 to 923K. While COK-12 has been prepared by self-assembly method using long chain ionic surfactant i.e., P123 as template, cobalt oxide supported on COK-12 catalysts with variable Co content have been synthesised by simple wet impregnation technique. All the catalysts were characterized by N2 adsorption - desorption, XRD, FT-IR, TPR, UV-Vis and XPS techniques. XRD and pore size distribution studies indicate the intactness of mesoporous structure of SiO2 even after incorporation of Co3O4. Presence of Co3O4 crystallites were observed beyond 5 wt% Co loading. High ethylbenzene conversion and stable styrene yields have been observed over 3% Co3O4/COK-12 catalyst due to the presence of large number of active Co3O4 catalytic sites. Enhancement in the activity has been observed with CO2 as soft oxidant than with N2 as diluent. This is because of the fact that the liberated H2 reacts with CO2 in the form of reverse water gas shift reaction.

  15. Highly Ordered Mesoporous Metal Oxides as Catalysts for Dehydrogenation of Cyclohexanol

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eunok; Jin, Mingshi; Kim, Ji Man [Sungkyunkwan University, Suwon (Korea, Republic of)

    2013-08-15

    Cyclohexanone is important intermediate for the manufacture of caprolactam which is monomer of nylron. Cyclohexanone is generally produced by dehydrogenation reaction of cyclohexanol. In this study, highly mesoporous metal oxides such as meso-WO{sub 3}, meso-TiO{sub 2}, meso-Fe{sub 2}O{sub 3}, meso-CuO, meso-SnO{sub 2} and meso-NiO were synthesized using mesoporous silica KIT-6 as a hard template via nano-replication method for dehydrogenation of cyclohexanol. The overall conversion of cyclohexanol followed a general order: meso-WO{sub 3} >> meso-Fe{sub 2}O{sub 3} > meso-SnO{sub 2} > meso-TiO{sub 2} > meso-NiO > meso-CuO. In particular, meso-WO{sub 3} significantly showed higher activity than the other mesoporous metal oxides. Therefore, the meso-WO{sub 3} has wide range of application possibilities for dehydrogenation of cyclohexanol.

  16. Oxidative Dehydrogenation of Butane to Butadiene and Butene Using a Novel Inert Membrane Reactor

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The oxidative dehydrogenation of butane to butadiene and butene was studied using a conventional fixed-bed ractor (FBR), inert membrane reactor (IMR) and mixed inert membrane reactor (MIMR). When IMR and MIMR were employed, a ceramic membrane modified by partially coating with glaze was used to distribute oxygen to a fixed-bed of 24-V-Mg-O catalyst. The oxygen partial pressure in the catalyst bed could be decreased. The effect of feeding modes and operation conditions were investigated. The selectivity of C4 dehydrogenation products (butene and butadiene) was found to be higher in IMR than in FBR. The feeding mode with 20% of air mixing with butane in MIMR was found to be more efficient than the feeding mode with all air permeating through ceramic membrane. The MIMR gave the most smooth temperature profile along the bed.

  17. Dehydrogenation of propane in the presence of carbon dioxide over chromium and gallium oxides catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Gaidai, N.A.; Nekrasov, N.V.; Menshova, M.V.; Kunusova, R.M. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Inst. of Organic Chemistry

    2011-07-01

    Effective chromium and gallium oxides supported catalysts were prepared and tested in longduration experiments for propane dehydrogenation in the presence of CO{sub 2}. The optimal concentrations of active metals were found. It was shown that the activity, selectivity and stability of chromium oxides catalysts were higher than these parameters for gallium ones. Mechanism of propane oxidative dehydrogenation was studied over both catalysts using unstationary and spectroscopic methods. The employment of these methods allowed to establish the differences in process mechanism. It was shown that surface hydroxides took participation in propene formation over Cr-catalysts and hydrides - over Ga-ones. Propane and carbon dioxide participated in the reaction from the adsorbed state over both catalysts but they were differed by the adsorption capacity of the reaction components: CO2 was tied more firmly than C{sub 3}H{sub 6} over both catalysts, CO{sub 2} and C{sub 3}H{sub 6} were tied more strongly with Cr-catalysts than with Ga-ones. It was shown that CO{sub 2} took active participation in reverse watergas shift reaction and in oxidation of catalyst surface over chromium oxides catalysts. The main role of CO{sub 2} in propane dehydrogenation over gallium catalysts consisted in a decrease of coke formation. Step-schemes of propene and cracking products formation were proposed on the basis of literature and obtained data: via the redox mechanism over Cr-catalysts and through a heterolytic dissociation reaction pathway over Ga-ones. (orig.)

  18. Modifying the catalytic and adsorption properties of metals and oxides

    Science.gov (United States)

    Yagodovskii, V. D.

    2015-11-01

    A new approach to interpreting the effect of promoters (inhibitors) of nonmetals and metals added to a host metal (catalyst) is considered. Theoretical calculations are based on a model of an actual two-dimensional electron gas and adsorbate particles. An equation is derived for the isotherm of induced adsorption on metals and semiconductors with respect to small fillings of θ ~ 0.1-0.15. The applicability of this equation is verified experimentally for metals (Ag, Pd, Cu, Fe, and Ni), graphitized ash, and semiconductor oxides Ta2O5, ZnO, and Ni. The applicability of the theoretical model of promotion is verified by the hydrogenation reaction of CO on ultradispersed nickel powder. The use of plasmachemical surface treatments of metals and oxides, accompanied by an increase in activity and variation in selectivity, are investigated based on the dehydrocyclization reactions of n-hexane and the dehydrogenation and dehydration of alcohols. It is established that such treatments for metals (Pt, Cu, Ni, and Co) raise their activity due to the growth of the number of active centers upon an increase in the activation energy. Applying XPES and XRD methods to metallic catalysts, it is shown that the rise in activity is associated with a change in their surface states (variation in the structural characteristics of metal particles and localization of certain forms of carbon in catalytically active centers). It is shown that plasmachemical treatments also alter their surface composition, surface activity, and raise their activity when used with complex phosphate oxides of the NASICON type. It is shown by the example of conversion of butanol-2 that abrupt variations in selectivity (prevalence of dehydration over dehydrogenation and vice versa) occur, depending on the type of plasma. It is concluded that plasmachemical treatments of metals and ZnO and NiO alter the isosteric heats and entropies of adsorption of isopropanol.

  19. Effects of CeO2 Support Facets on VOx/CeO2 Catalysts in Oxidative Dehydrogenation of Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Peden, Charles HF; Wang, Yong

    2014-05-13

    CeO2 supports with dominating facets, i.e., low index (100), (110) and (111) facets, are prepared. The facet effects on the structure and catalytic performance of supported vanadium oxide catalysts are investigated using oxidative dehydrogenation of methanol as a model reaction. In the presence of mixed facets, Infrared and Raman characterizations demonstrate that surface vanadia species preferentially deposit on CeO2 (100) facets, presumably because of its higher surface energy. At the same surface vanadium densities, VOx species on (100) facets show better dispersion, followed by (110) and (111) facets. The VOx species on CeO2 nanorods with (110) and (100) facets display higher activity and lower apparent activation energies compared to that on CeO2 nanopolyhedras with dominating (111) facets and CeO2 nanocubes with dominating (100) facets. The higher activity for VOx/CeO2(110) might be related to the more abundant oxygen vacancies present on the (110) facets, evidenced from Raman spectroscopic measurements.

  20. Oxidative Dehydrogenation of Ethane to Ethylene over LiCI/MnOx/PC Catalysts

    Institute of Scientific and Technical Information of China (English)

    葛庆杰; 李文钊; 于春英; 徐恒泳

    2001-01-01

    The caalytic stability of LiCl/MnOx/PC catalyst have been investigated, the deactivation mechanism was discussed. Tne experimental results show that ethane conversion decreases and etihylene selectivotu keeps about 90% as reaction time increases. The main deactivation reasons LiCI/MnOx/PCcatalyst for oxidative dehydrogenation of ethane (ODHE) to ethylene are the transiton of active species Mn2O3 TO MnOspecies and the loss of active component Cl in catalyst. Instead of ethane with FCC tailed-gas, the stability of LiCl/MnOx/PC catalyst has been largely improved.

  1. Oxidative Dehydrogenation of n-Butenes over BiFe{sub 0.65}MoP{sub 0.1} Oxide Catalysts Prepared with Various Synthesis Method

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung-Hyun; Shin, Chae-Ho [Chungbuk National University, Cheongju (Korea, Republic of)

    2015-02-15

    To investigate the effect of the catalyst synthesis method on the oxidative dehydrogenation (ODH) of n-butenes, BiFe{sub 0.65}MoP{sub 0.1} oxide catalysts were prepared with various synthesis methods such as co-precipitation, citric acid method, hydrothermal method, and surfactant templated method. The catalysts were characterized by X-ray Diffraction (XRD), N{sub 2} sorption, and NH{sub 3}/1-butene-temperature programmed desorption (NH{sub 3}/1-butene-TPD) to correlate with catalytic activity in ODH reaction. Among the catalysts studied here, BiFe{sub 0.65}MoP{sub 0.1} oxide catalyst prepared with co-precipitation method marked the highest activity showing 1-butene conversion, 79.5%, butadiene selectivity, 85.1% and yield, 67.7% after reaction for 14 h. From the result of NH{sub 3}-TPD, the catalytic activity is closely related to the acidity of the BiFe{sub 0.65}MoP{sub 0.1}-x oxide catalyst and acidity of the BiFe{sub 0.65}MoP{sub 0.1} oxde catalyst prepared with co-precipitation method was higher than that of other catalysts. In addition, combined with the 1-butene TPD, the higher catalytic activity is closely related to the amount of weakly adsorbed intermediate (<200 .deg. C) and the desorbing temperature of strongly adsorbed intermediates (>200 .deg. C)

  2. Influence of preparation conditions of hollow titania–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

    International Nuclear Information System (INIS)

    Highlights: • We study influence of preparation conditions on activity of hollow titania–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH3BH3 increases with increase of Ti + Ni content. • The activity depends on the amount of PS residue in the hollow spheres. - Abstract: The present work reports influence of preparation conditions of hollow titania–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane (NH3BH3). The as-prepared hollow titania–nickel composite spheres were characterized by transmission electron microscopy (TEM). Catalytic activities of the hollow spheres for hydrolytic dehydrogenation of aqueous NaBH4/NH3BH3 solution improve with the decrease of Ti + Ni content. From the results of FTIR spectra and elemental analysis, the amount of residual polystyrene (PS) templates is able to be reduced by increasing aging time for the preparation, and the catalytic activity of the hollow spheres increases when the amount of residual PS templates decreases. The carbon content in the hollow spheres prepared with aging time = 24 h is 17.3 wt.%, and the evolution of 62 mL hydrogen is finished in about 22 min in the presence of the hollow spheres from aqueous NaBH4/NH3BH3 solution. The molar ratio of the hydrolytically generated hydrogen to the initial NH3BH3 in the presence of the hollow spheres is 2.7

  3. Phosphate-Doped Carbon Black as Pt Catalyst Support: Co-catalytic Functionality for Dimethyl Ether and Methanol Electro-oxidation

    DEFF Research Database (Denmark)

    Yin, Min; Huang, Yunjie; Li, Qingfeng;

    2014-01-01

    supported Pt catalysts show significant improvement in catalytic activity towards the direct oxidation of methanol and DME, attributable to the enhanced adsorption and dehydrogenation of methanol and DME, as well as the presence of activated OH species in the catalysts. The latter is demonstrated to...

  4. Role of Platinum Deposited on TiO2 in Photocatalytic Methanol Oxidation and Dehydrogenation Reactions

    Directory of Open Access Journals (Sweden)

    Luma M. Ahmed

    2014-01-01

    Full Text Available Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100. The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, atomic force microscopy (AFM, and UV-visible diffuse spectrophotometry (UV-Vis. XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO2 was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO2 for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.

  5. Incorporation of catalytic dehydrogenation into Fischer-Tropsch synthesis of liquid fuels from coal to minimize carbon dioxide emissions

    Energy Technology Data Exchange (ETDEWEB)

    Gerald P. Huffman [University of Kentucky, Lexington, KY (United States). Consortium for Fossil Fuel Science and Department of Chemical & Materials Engineering

    2011-08-15

    Synthesis gas (syngas) produced from coal typically has hydrogen to carbon monoxide ratios in the range of approximately 0.7-1.1, depending on the gasification method. In order to produce liquid fuels from this syngas by Fischer-Tropsch synthesis (FTS), these ratios must be raised to 2.0 or higher. If this is accomplished by the water-gas shift reaction, the traditional method, large emissions of carbon dioxide are produced. In this paper, it is shown that catalytic dehydrogenation (CDH) of the gaseous C1-C4 products of FT synthesis and recycling of the resulting hydrogen to the syngas feed-stream can increase the H{sub 2}/CO ratio to the desired values with little or no production of carbon dioxide. All carbon from the CDH reaction is in the form of a potentially valuable by-product, multi-walled carbon nanotubes (MWCNT). The amounts of hydrogen and MWCNT produced, carbon dioxide emissions avoided, and water saved are calculated for a 50,000 bbl/day FTS-CDH plant and it is demonstrated that the energy balance for the process is favorable. Methods of utilizing the large quantity of MWCNT produced are discussed. 50 refs., 6 figs., 3 tabs.

  6. Deactivation of a mixed oxide catalyst of Mo-V-Te-Nb-O composition in the reaction of oxidative ethane dehydrogenation

    Science.gov (United States)

    Mishanin, I. I.; Kalenchuk, A. N.; Maslakov, K. I.; Lunin, V. V.; Koklin, A. E.; Finashina, E. D.; Bogdan, V. I.

    2016-06-01

    The operational stability of a mixed oxide catalyst of Mo-V-Te-Nb-O composition in the oxidative dehydrogenation of ethane (ratio of C2H6: O2 = 3: 1) is studied in a flow reactor at temperatures of 340-400°C, a pressure of 1 atm, and a WHSV of the feed mixture of 800 h-1. It is found that the selectivity toward ethylene is 98% at 340°C, but the conversion of ethane at this temperature is only 6%; when the temperature is raised to 400°C, the conversion of ethane is increased to 37%, while the selectivity toward ethylene is reduced to 85%. Using physical and chemical means (XPS, SEM), it is found that the lack of oxidant in the reaction mixture leads to irreversible changes in the catalyst, i.e., reduced selectivity and activity. Raising the reaction temperature to 400°C allows the reduction of tellurium by ethane, from the +6 oxidation state to the zerovalent state, with its subsequent sublimation and the destruction of the catalytically active and selective phase; in its characteristics, the catalyst becomes similar to the Mo-V-Nb-O system containing no tellurium.

  7. The catalytic effect of Nb, NbO and Nb{sub 2}O{sub 5} with different surface planes on dehydrogenation in MgH{sub 2}: Density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Keisuke, E-mail: keisuke.takahashi@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, N-13, W-8, Sapporo 060-8628 (Japan); Isobe, Shigehito [Strategic Priority Project Research Division, Creative Research Institution, Hokkaido University (Japan); Ohnuki, Somei [Graduate School of Engineering, Hokkaido University, N-13, W-8, Sapporo 060-8628 (Japan)

    2013-12-15

    Highlights: ► Dehydrogenation of MgH{sub 2} cluster on (1 0 0)(1 1 0)(1 1 1) of Nb, NbO and Nb{sub 2}O{sub 5}. ► NbO(1 1 1) shows very high adsorption energy. ► MgO forms on all of Nb{sub 2}O{sub 5} planes. ► Density of state reveals that dehydrogenated Mg on NbO(1 1 1) is unstable and may be easy to rehydrogenate. -- Abstract: The catalytic effect of Nb, NbO and Nb{sub 2}O{sub 5} with different surface planes on dehydrogenation of MgH{sub 2} clusters was investigated by using a density functional theory. The adsorption sites of Mg and H are different depending on different surface planes. In particular, NbO(1 1 1) shows very high adsorption energy which is considered to be due to electron pairing instead of a charge transfer. Electronic structure reveal that NbO(1 1 1) has a strong interaction between the s-state of H and d-state of Nb. This thermodynamically suggests a low dissociation barrier of Mg–H bond. Mg becomes fully oxide on a oxygen-rich planes of NbO(1 0 0) and all planes of Nb{sub 2}O{sub 5}. Those planes prevent rehydrogenation of MgH{sub 2}. These results should help understand the catalytic effects of Nb, NbO and Nb{sub 2}O{sub 5} and develop a better catalyst for MgH{sub 2} systems.

  8. Oxidative Dehydrogenation of n-Butane over LaV Catalysts Supported on TiO2

    Directory of Open Access Journals (Sweden)

    Le Minh Cam

    2013-01-01

    Full Text Available The catalytic performance of vanadia catalysts with 15 wt% V supported on TiO2 and (15 wt% V + 4.6 wt% La supported on TiO2 in oxidative dehydrogenation (ODH of n-butane was investigated. The catalysts were characterized by means of TPD-NH3, TPR-H2, UV-Vis, and BET. Testing of samples showed that vanadia catalysts were active for the reaction. It was found that La doping of V/TiO2 catalyst had a negative effect on the dispersion of V species and led to formation of V2O5 clusters. This resulted in a loss of activity. Although slight improvement of selectivity was observed in comparison to undoped V/TiO2 samples due to lower acidity of La-doped –V/TiO2, this could not compensate the loss of activity and finally did not lead to higher butene yields.

  9. In situ formed catalytically active ruthenium nanocatalyst in room temperature dehydrogenation/dehydrocoupling of ammonia-borane from Ru(cod)(cot) precatalyst.

    Science.gov (United States)

    Zahmakiran, Mehmet; Ayvalı, Tuğçe; Philippot, Karine

    2012-03-20

    The development of simply prepared and effective catalytic materials for dehydrocoupling/dehydrogenation of ammonia-borane (AB; NH(3)BH(3)) under mild conditions remains a challenge in the field of hydrogen economy and material science. Reported herein is the discovery of in situ generated ruthenium nanocatalyst as a new catalytic system for this important reaction. They are formed in situ during the dehydrogenation of AB in THF at 25 °C in the absence of any stabilizing agent starting with homogeneous Ru(cod)(cot) precatalyst (cod = 1,5-η(2)-cyclooctadiene; cot = 1,3,5-η(3)-cyclooctatriene). The preliminary characterization of the reaction solutions and the products was done by using ICP-OES, ATR-IR, TEM, XPS, ZC-TEM, GC, EA, and (11)B, (15)N, and (1)H NMR, which reveal that ruthenium nanocatalyst is generated in situ during the dehydrogenation of AB from homogeneous Ru(cod)(cot) precatalyst and B-N polymers formed at the initial stage of the catalytic reaction take part in the stabilization of this ruthenium nanocatalyst. Moreover, following the recently updated approach (Bayram, E.; et al. J. Am. Chem. Soc.2011, 133, 18889) by performing Hg(0), CS(2) poisoning experiments, nanofiltration, time-dependent TEM analyses, and kinetic investigation of active catalyst formation to distinguish single metal or in the present case subnanometer Ru(n) cluster-based catalysis from polymetallic Ru(0)(n) nanoparticle catalysis reveals that in situ formed Ru(n) clusters (not Ru(0)(n) nanoparticles) are kinetically dominant catalytically active species in our catalytic system. The resulting ruthenium catalyst provides 120 total turnovers over 5 h with an initial turnover frequency (TOF) value of 35 h(-1) at room temperature with the generation of more than 1.0 equiv H(2) at the complete conversion of AB to polyaminoborane (PAB; [NH(2)BH(2)](n)) and polyborazylene (PB; [NHBH](n)) units. PMID:22356554

  10. Electro Catalytic Oxidation (ECO) Operation

    Energy Technology Data Exchange (ETDEWEB)

    Morgan Jones

    2011-03-31

    The power industry in the United States is faced with meeting many new regulations to reduce a number of air pollutants including sulfur dioxide, nitrogen oxides, fine particulate matter, and mercury. With over 1,000 power plants in the US, this is a daunting task. In some cases, traditional pollution control technologies such as wet scrubbers and SCRs are not feasible. Powerspan's Electro-Catalytic Oxidation, or ECO{reg_sign} process combines four pollution control devices into a single integrated system that can be installed after a power plant's particulate control device. Besides achieving major reductions in emissions of sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), fine particulate matter (PM2.5) and mercury (Hg), ECO produces a highly marketable fertilizer, which can help offset the operating costs of the process system. Powerspan has been operating a 50-MW ECO commercial demonstration unit (CDU) at FirstEnergy Corp.'s R.E. Burger Plant near Shadyside, Ohio, since February 2004. In addition to the CDU, a test loop has been constructed beside the CDU to demonstrate higher NOx removal rates and test various scrubber packing types and wet ESP configurations. Furthermore, Powerspan has developed the ECO{reg_sign}{sub 2} technology, a regenerative process that uses a proprietary solvent to capture CO{sub 2} from flue gas. The CO{sub 2} capture takes place after the capture of NOx, SO{sub 2}, mercury, and fine particulate matter. Once the CO{sub 2} is captured, the proprietary solution is regenerated to release CO{sub 2} in a form that is ready for geological storage or beneficial use. Pilot scale testing of ECO{sub 2} began in early 2009 at FirstEnergy's Burger Plant. The ECO{sub 2} pilot unit is designed to process a 1-MW flue gas stream and produce 20 tons of CO{sub 2} per day, achieving a 90% CO{sub 2} capture rate. The ECO{sub 2} pilot program provided the opportunity to confirm process design and cost estimates, and prepare for large

  11. Inlfuence of the Alkali Treatment of HZSM-5 Zeolite on Catalytic Performance of PtSn-Based Catalyst for Propane Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Huang Li; Zhou Shijian; Zhou Yuming; Zhang Yiwei; Xu Jun; Wang Li

    2013-01-01

    The porous material ATZ with micro-mesopore hierarchical porosity was prepared by alkali treatment of parent HZSM-5 zeolite and applied for propane dehydrogenation. The zeolite samples were characterized by XRD, N2-physisorption, and NH3-TPD analysis. The results showed that the alkali treatment can modify the physicochemical prop-erties of HZSM-5 zeolite. In this case, the porous material ATZ showed larger external surface area with less acid sites as compared to the HZSM-5 zeolite. It was found out that the alkali treatment of HZSM-5 zeolite could promote the catalytic performance of PtSn/ATZ catalyst. The possible reason was ascribed to the low acidity of ATZ. Furthermore, the presence of mesopores could reduce the carbon deposits on the metallic surface, which was also favorable for the dehydrogenation reaction.

  12. Catalytic oxidation of dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Zelenay, Piotr; Wu, Gang; Johnston, Christina M.; Li, Qing

    2016-05-10

    A composition for oxidizing dimethyl ether includes an alloy supported on carbon, the alloy being of platinum, ruthenium, and palladium. A process for oxidizing dimethyl ether involves exposing dimethyl ether to a carbon-supported alloy of platinum, ruthenium, and palladium under conditions sufficient to electrochemically oxidize the dimethyl ether.

  13. Novel Flower-Like Ag-SiO2-MgO-Al2O3 Material: Preparation, Characterization and Catalytic Application in Methanol Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    LI,Jing-Xia; REN,Li-Ping; DAI,Wei-Lin; CAO,Yong; FAN,Kang-Nian

    2008-01-01

    Catalytic direct dehydrogenation of methanol to formaldehyde was carried out over Ag-SiO2-MgO-Al2O3 catalysts prepared by sol-gel method.The optimal preparation mass fractions were determined as 8.3% MgO,16.5% Al2O3 and 20% silver loading.Using this optimum catalyst,excellent activity and selectivity were obtained.The conversion of methanol and the selectivity to formaldehyde both reached 100%,which were much higher than other previously reported silver supported catalysts.Based on combined characterizations,such as X-ray diffraction (XRD),scanning electronic microscopy (SEM),diffuse reflectance ultraviolet-visible spectroscopy (UV-Vis,DRS),nitrogen adsorption at low temperature,temperature programmed desorption of ammonia (NH3-TPD),desorption of CO2 (CO2-TPD),etc.,the correlation of the catalytic performance to the structural properties of the Ag-SiO2-MgO-Al2O3 catalyst was discussed in detail.This perfect catalytic performance in the direct dehydrogenation of methanol to formaldehyde without any side-products is attributed to its unique flower-like structure with a surface area less than 1 m2/g,and the strong interactions between neutralized support and the nano-sized Ag particles as active centers.

  14. Influence of preparation conditions of hollow titania–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Umegaki, Tetsuo, E-mail: umegaki.tetsuo@nihon-u.ac.jp [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Ohashi, Takato [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Xu, Qiang [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kojima, Yoshiyuki [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan)

    2014-04-01

    Highlights: • We study influence of preparation conditions on activity of hollow titania–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH{sub 3}BH{sub 3} increases with increase of Ti + Ni content. • The activity depends on the amount of PS residue in the hollow spheres. - Abstract: The present work reports influence of preparation conditions of hollow titania–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane (NH{sub 3}BH{sub 3}). The as-prepared hollow titania–nickel composite spheres were characterized by transmission electron microscopy (TEM). Catalytic activities of the hollow spheres for hydrolytic dehydrogenation of aqueous NaBH{sub 4}/NH{sub 3}BH{sub 3} solution improve with the decrease of Ti + Ni content. From the results of FTIR spectra and elemental analysis, the amount of residual polystyrene (PS) templates is able to be reduced by increasing aging time for the preparation, and the catalytic activity of the hollow spheres increases when the amount of residual PS templates decreases. The carbon content in the hollow spheres prepared with aging time = 24 h is 17.3 wt.%, and the evolution of 62 mL hydrogen is finished in about 22 min in the presence of the hollow spheres from aqueous NaBH{sub 4}/NH{sub 3}BH{sub 3} solution. The molar ratio of the hydrolytically generated hydrogen to the initial NH{sub 3}BH{sub 3} in the presence of the hollow spheres is 2.7.

  15. Catalytic De/hydrogenation in Mg by co-doped Ni and VO{sub x} on active carbon: extremely fast kinetics at low temperatures and high hydrogen capacity

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Yi; Cheng, Lina [ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, Brisbane (Australia); School of Mechanical and Mining Engineering, University of Queensland, Brisbane (Australia); Pan, Nan [Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei (China); Zou, Jin [School of Mechanical and Mining Engineering, University of Queensland, Brisbane (Australia); Lu, Gaoqing (Max) [ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, Brisbane (Australia); Yao, Xiangdong [ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, Brisbane (Australia); Queensland Micro- and Nanotechnology Centre (QMNC), Griffith University, Brisbane (Australia)

    2011-05-15

    A multi-component catalyst Ni-VO{sub x}/AC (VO{sub x} is comprised of V{sub 2}O{sub 5} and VO{sub 2}, x = 2.18) was synthesized by a wet impregnation method. The synthesized Ni-VO{sub x}/AC shows a superior catalytic effect on de/hydrogenation of Mg. The MgH{sub 2}+Ni-VO{sub x}/AC composites can absorb 6.2 wt.-% hydrogen within only 1 min at 150 C under a hydrogen pressure of 2 MPa and desorb 6.5 wt.-% hydrogen within 10 min at 300 C under an initial hydrogen pressure of 1 KPa, which overcomes a critical barrier for practical use of Mg as a hydrogen storage material. A significant decrease of activation energy (E{sub a}) indicates that Ni-VO{sub x}/AC catalyst is highly efficient for Mg de/hydrogenation, which may be ascribed to the synergistic effect of bimetals (metal oxides) and nanocarbon. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Biomimetic, Catalytic Oxidation in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    Shun-lchi Murahashi

    2005-01-01

    @@ 1Introduction Oxidation is one of the most fundamental reactions in organic synthesis. Owing to the current need to develop forward-looking technology that is environmentally acceptable with respect many aspects. The most attractive approaches are biomimetic oxidation reactions that are closely related to the metabolism of living things. The metabolisms are governed by a variety of enzymes such as cytochrome P-450 and flavoenzyme.Simulation of the function of these enzymes with simple transition metal complex catalyst or organic catalysts led to the discovery of biomimetic, catalytic oxidations with peroxides[1]. We extended such biomimetic methods to the oxidation with molecular oxygen under mild conditions.

  17. Catalytic oxidation of industrial organic solvent vapors.

    Science.gov (United States)

    Tzortzatou, Katerina; Grigoropoulou, Eleni

    2010-01-01

    In the present study the catalytic oxidation of an industrial organic solvent consisting predominantly of C-9 to C-10 paraffins and napthtenics and derived from low aromatic white spirit on CuO and Pt catalysts was investigated at ambient pressure and temperatures between 330 and 770 K. Catalysts were prepared in the laboratory and compared to commercial ones. Characterization was based on x-ray diffraction (XRD) analysis, x-ray fluorescence (XRF) analysis, scanning electron microscope (SEM) analysis and nitrogen adsorption data. The commercial platinum catalyst was proved highly efficient in the oxidation of the commercial solvent, necessitating lower temperatures for total oxidation. Catalyst loading in active component is clearly not of primordial importance, since its dispersion and crystallinity as well as the presence of other metallic compounds influence also the catalytic activity. In the case of copper catalysts studied, the different support (alumina) characteristics also would contribute to the difference in catalytic activity. Finally, the power law kinetics may successfully be used in order to explain the catalytic oxidation data of the organic solvent, where its constituents are modeled as a single carbon-containing compound. PMID:20390900

  18. Electrochemical promotion of sulfur dioxide catalytic oxidation

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bandur, Viktor; Cappeln, Frederik Vilhelm;

    2000-01-01

    The effect of electrochemical polarization on the catalytic SO2 oxidation in the molten V2O5-K2S2O7 system has been studied using a gold working electrode in the temperature range 400-460 degrees C. A similar experiment has been performed with the industrial catalyst VK-58. The aim of the present...

  19. Catalytic oxidations by vanadium complexes

    OpenAIRE

    Ligtenbarg, A.G J; Hage, R.; Feringa, B. L.

    2003-01-01

    Vanadium haloperoxidases catalyse the oxidation of halides leading to halogenation of substrates or, in the absence of suitable substrates, to oxidation of hydrogen peroxide into singlet oxygen and water. Furthermore, V-haloperoxidases are capable to give enantioselective sulfoxidation under the appropriate conditions. The most interesting model compounds that have been synthesised and studied as bromination catalysts, and catalysts for, i.e. epoxidation, hydroxylation, sulfoxidation and alco...

  20. The role of molecular oxygen in the iron(III)-promoted oxidative dehydrogenation of amines.

    Science.gov (United States)

    Saucedo-Vázquez, Juan Pablo; Kroneck, Peter M H; Sosa-Torres, Martha Elena

    2015-03-28

    A mechanistic study is presented of the oxidative dehydrogenation of the iron(III) complex [Fe(III)L(3)](3+), 1, (L(3) = 1,9-bis(2'-pyridyl)-5-[(ethoxy-2''-pyridyl)methyl]-2,5,8-triazanonane) in ethanol in the presence of molecular oxygen. The product of the reaction was identified by NMR spectroscopy and X-ray crystallography as the identical monoimine complex [Fe(II)L(4)](2+), 2, (L(4) = 1,9-bis(2'-pyridyl)-5-[(ethoxy-2''-pyridyl)methyl]-2,5,8-triazanon-1-ene) also formed under an inert nitrogen atmosphere. Molecular oxygen is an active player in the oxidative dehydrogenation of iron(III) complex 1. Reduced oxygen species, e.g., superoxide, (O2˙(-)) and peroxide (O2(2-)), are formed and undergo single electron transfer reactions with ligand-based radical intermediates. The experimental rate law can be described by the third order rate equation, -d[(Fe(III)L(3))(3+)]/dt = kOD[(Fe(III)L(3))(3+)][EtO(-)][O2], with kOD = 3.80 ± 0.09 × 10(7) M(-2) s(-1) (60 °C, μ = 0.01 M). The reduction O2 → O2˙(-) represents the rate determining step, with superoxide becoming further reduced to peroxide as shown by a coupled heme catalase assay. In an independent study, with H2O2, replacing O2 as the oxidant, the experimental rate law depended on [H2O2]: -d[(Fe(III)L(3))(3+)]/dt = kH2O2[(Fe(III)L(3))(3+)][H2O2]), with kH2O2 = 6.25 ± 0.02 × 10(-3) M(-1) s(-1). In contrast to the reaction performed under N2, no kinetic isotope effect (KIE) or general base catalysis was found for the reaction of iron(III) complex 1 with O2. Under N2, two consecutive one-electron oxidation steps of the ligand coupled to proton removal produced the iron(II)-monoimine complex [Fe(II)L(4)](2+) and the iron(II)-amine complex [Fe(II)L(3)](2+) in a 1 : 1 ratio (disproportionation), with the amine deprotonation being the rate determining step. Notably, the reaction is almost one order of magnitude faster in the presence of O2, with kEtO(-) = 3.02 ± 0.09 × 10(5) M(-1) s(-1) (O2) compared to k

  1. CO2-enhanced dehydrogenation of ethane over sonochemically synthesized Cr/clinoptilolite-ZrO2 nanocatalyst: Effects of ultrasound irradiation and ZrO2 loading on catalytic activity and stability.

    Science.gov (United States)

    Rahmani, Farhad; Haghighi, Mohammad; Mahboob, Salar

    2016-11-01

    CO2-enhanced oxidative dehydrogenation of ethane was investigated over sonochemically synthesized Cr/clinoptilolite-ZrO2 nanocatalyst with the aim of assessing the effect of composite support and ultrasonic irradiation on the nanocatalyst reactivity and stability. To this aim, ZrO2 promoted clinoptilolite supports varying in zirconia content (0, 25, 50wt%) were synthesized by hydrothermally precipitation method and impregnated with chromium nitrate under ultrasound irradiation. The samples were characterized by XRD, FESEM, EDX, TEM, ICP, BET, FTIR, TPR-H2 and TPD-NH3 techniques. The characterization results indicated that ultrasound irradiation could not only reduce the formation of Cr2O3 and decrease submicron particle size of chromium oxide to nanometer scale, but also promote the distribution of metallic particles and strengthen the chromium-support interaction. As a result, utilizing ultrasound irradiation in the synthesis of Cr/Clinoptilolite helped to maintain a high and stable catalytic activity. These features were more prominent in the presence of zirconia. It was found that the metal oxide nanoparticles with about 4-8nm are dispersed uniformly on the surface of composite support containing 25wt% ZrO2 (CLT-Z25). Moreover, the addition of ZrO2 resulted in the formation of new strong acid sites and a significant modification in the reducibility of chromium species, which alongside homogenous and small Cr nanoparticles account for the superior catalytic performance of ZrO2 containing samples. However, excessive loading of ZrO2 (50wt%) severely covered the surface of clinoptilolite, afforded the aggregations of metallic particles and thereupon, weakened the contact between clinoptilolite and ZrO2, which together with more acid strength seriously resulted in the deactivation of catalyst. In spite of superior initial activity of ZrO2-rich sample among the catalysts tested, ultrasonic synthesized Cr/CLT-Z25 nanocatalyst showed the best catalytic performance after

  2. Formaldehyde degradation by catalytic oxidation.

    OpenAIRE

    Shirey, W N; Hall, T. A.; Hanel, E; Sansone, E B

    1981-01-01

    Formaldehyde used for the disinfection of a laminar-flow biological safety cabinet was oxidatively degraded by using a catalyst. This technique reduced the formaldehyde concentration in the cabinet from about 5,000 to about 45 mg/m3 in 8 h. This technique should prove useful in other applications.

  3. Mechanistic understanding and kinetic studies of highly selective oxidative dehydrogenation of ethane over novel supported molten chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen, Garching (Germany). Dept. of Chemistry

    2012-07-01

    Ethene is one of the most important feedstocks for chemical industry, nowadays mainly produced via steam cracking. However, oxidative dehydrogenation becomes a more important process route, allowing to produce ethene selectively and at lower temperatures. Supported alkali chloride catalysts are promising materials. However, the ODH mechanism of this class of catalysts is not well investigated so far. The investigation of the reaction mechanism is thus the aim of this contribution. (orig.)

  4. Making coke a more efficient catalyst in the oxidative dehydrogenation of ethylbenzene using wide-pore transitional aluminas

    OpenAIRE

    Zarubina, V.; Nederlof, C.; B. VAN DER LINDEN; F. Kapteijn; Heeres, H. J.; Makkee, M.; Melián-Cabrera, I.

    2014-01-01

    The thermal activation of a silica-stabilized gamma-alumina impacts positively on the oxidative dehydrogenation of ethylbenzene (EB) to styrene (ST). A systematic thermal study reveals that the transition from gamma-alumina into transitional phases at 1050 degrees C leads to an optimal enhancement of both conversion and selectivity under pseudo-steady state conditions; where active and selective coke have been deposited. The effect is observed in the reaction temperature range of 450-475 degr...

  5. A biomimetic pathway for vanadium-catalyzed aerobic oxidation of alcohols: evidence for a base-assisted dehydrogenation mechanism.

    Science.gov (United States)

    Wigington, Bethany N; Drummond, Michael L; Cundari, Thomas R; Thorn, David L; Hanson, Susan K; Scott, Susannah L

    2012-11-19

    The first step in the catalytic oxidation of alcohols by molecular O(2), mediated by homogeneous vanadium(V) complexes [LV(V)(O)(OR)], is ligand exchange. The unusual mechanism of the subsequent intramolecular oxidation of benzyl alcoholate ligands in the 8-hydroxyquinolinato (HQ) complexes [(HQ)(2)V(V)(O)(OCH(2)C(6)H(4)-p-X)] involves intermolecular deprotonation. In the presence of triethylamine, complex 3 (X = H) reacts within an hour at room temperature to generate, quantitatively, [(HQ)(2)V(IV)(O)], benzaldehyde (0.5 equivalents), and benzyl alcohol (0.5 equivalents). The base plays a key role in the reaction: in its absence, less than 12% conversion was observed after 72 hours. The reaction is first order in both 3 and NEt(3), with activation parameters ΔH(≠)=(28±4) kJ mol(-1) and ΔS(≠)=(-169±4) J K(-1)  mol(-1). A large kinetic isotope effect, 10.2±0.6, was observed when the benzylic hydrogen atoms were replaced by deuterium atoms. The effect of the para substituent of the benzyl alcoholate ligand on the reaction rate was investigated using a Hammett plot, which was constructed using σ(p). From the slope of the Hammett plot, ρ=+(1.34±0.18), a significant buildup of negative charge on the benzylic carbon atom in the transition state is inferred. These experimental findings, in combination with computational studies, support an unusual bimolecular pathway for the intramolecular redox reaction, in which the rate-limiting step is deprotonation at the benzylic position. This mechanism, that is, base-assisted dehydrogenation (BAD), represents a biomimetic pathway for transition-metal-mediated alcohol oxidations, differing from the previously identified hydride-transfer and radical pathways. It suggests a new way to enhance the activity and selectivity of vanadium catalysts in a wide range of redox reactions, through control of the outer coordination sphere. PMID:23080554

  6. Influence of preparation conditions of hollow silica–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Umegaki, Tetsuo, E-mail: umegaki.tetsuo@nihon-u.ac.jp [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Seki, Ayano [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Xu, Qiang [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kojima, Yoshiyuki [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan)

    2014-03-05

    Highlights: • We study influence of preparation conditions on activity of hollow silica–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH{sub 3}BH{sub 3} increases with increase of Si+Ni content. • The particle size distribution affects the activity and reducibility of active nickel species. • The amount of PS residue in the hollow spheres decreases by treatment of as-prepared sample in toluene. -- Abstract: In this paper, we investigated influence of preparation conditions of hollow silica–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane. In the preparation method of this study, when silica–nickel composite shells were coated on polystyrene templates by the sol–gel method using L(+)-arginine as the promoter for the reaction to form silica–nickel composite shell, the polystyrene templates were dissolved subsequently, even synchronously, in the same medium to form hollow spheres. The as-prepared silica–nickel composite spheres were characterized by transmission electron microscopy and scanning electron microscopy. The effects of Si+Ni content on the morphology were systematically evaluated. All the as-prepared hollow silica–nickel composite spheres have the similar morphology as identified by SEM and TEM measurement. Homogeneity of the hollow silica–nickel composite spheres increases with the increase in the Si+Ni content as shown by the laser diffraction particle size analysis. The catalytic activities of the hollow silica–nickel composite spheres for hydrolytic dehydrogenation of ammonia borane prepared with different Si+Ni contents were compared. The catalytic activity for the hydrogen evolution in the presence of the hollow spheres increases with the increase of Si+Ni content. The results of FTIR spectra of the hollow silica–nickel composite spheres indicate that a certain amount of residual PS templates exists in hollow silica

  7. Influence of preparation conditions of hollow silica–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

    International Nuclear Information System (INIS)

    Highlights: • We study influence of preparation conditions on activity of hollow silica–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH3BH3 increases with increase of Si+Ni content. • The particle size distribution affects the activity and reducibility of active nickel species. • The amount of PS residue in the hollow spheres decreases by treatment of as-prepared sample in toluene. -- Abstract: In this paper, we investigated influence of preparation conditions of hollow silica–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane. In the preparation method of this study, when silica–nickel composite shells were coated on polystyrene templates by the sol–gel method using L(+)-arginine as the promoter for the reaction to form silica–nickel composite shell, the polystyrene templates were dissolved subsequently, even synchronously, in the same medium to form hollow spheres. The as-prepared silica–nickel composite spheres were characterized by transmission electron microscopy and scanning electron microscopy. The effects of Si+Ni content on the morphology were systematically evaluated. All the as-prepared hollow silica–nickel composite spheres have the similar morphology as identified by SEM and TEM measurement. Homogeneity of the hollow silica–nickel composite spheres increases with the increase in the Si+Ni content as shown by the laser diffraction particle size analysis. The catalytic activities of the hollow silica–nickel composite spheres for hydrolytic dehydrogenation of ammonia borane prepared with different Si+Ni contents were compared. The catalytic activity for the hydrogen evolution in the presence of the hollow spheres increases with the increase of Si+Ni content. The results of FTIR spectra of the hollow silica–nickel composite spheres indicate that a certain amount of residual PS templates exists in hollow silica–nickel composite

  8. Doped carbon nanostructures as metal-free catalysts for oxidative dehydrogenation of light alkanes

    OpenAIRE

    Jenssen, Kaia Andersson

    2014-01-01

    Catalytic reactions are often carried out on various supported metals, these usually being noble metals or metal oxides. Even though metal based catalysts plays a major role in today s industrial processes, they still have several disadvantages, including high cost, proneness to gas poisoning, as well as disadvantageous effect on the environment. Recently, certain carbon nanomaterials have been in the spotlight of several research groups, as carbon has the advantages of wide availability, env...

  9. CH4 dehydrogenation on Cu(1 1 1), Cu@Cu(1 1 1), Rh@Cu(1 1 1) and RhCu(1 1 1) surfaces: A comparison studies of catalytic activity

    International Nuclear Information System (INIS)

    Highlights: • Adsorbed Rh atom on Cu catalyst exhibits better catalytic activity for CH4 dehydrogenation. • The adsorbed Rh atom is the reaction active center for CH4 dehydrogenation. • The morphology of Cu substrate has negligible effect on CH4 dehydrogenation. - Abstract: In the CVD growth of graphene, the reaction barriers of the dehydrogenation for hydrocarbon molecules directly decide the graphene CVD growth temperature. In this study, density functional theory method has been employed to comparatively probe into CH4 dehydrogenation on four types of Cu(1 1 1) surface, including the flat Cu(1 1 1) surface (labeled as Cu(1 1 1)) and the Cu(1 1 1) surface with one surface Cu atom substituted by one Rh atom (labeled as RhCu(1 1 1)), as well as the Cu(1 1 1) surface with one Cu or Rh adatom (labeled as Cu@Cu(1 1 1) and Rh@Cu(1 1 1), respectively). Our results show that the highest barrier of the whole CH4 dehydrogenation process is remarkably reduced from 448.7 and 418.4 kJ mol−1 on the flat Cu(1 1 1) and Cu@Cu(1 1 1) surfaces to 258.9 kJ mol−1 on RhCu(1 1 1) surface, and to 180.0 kJ mol−1 on Rh@Cu(1 1 1) surface, indicating that the adsorbed or substituted Rh atom on Cu catalyst can exhibit better catalytic activity for CH4 complete dehydrogenation; meanwhile, since the differences for the highest barrier between Cu@Cu(1 1 1) and Cu(1 1 1) surfaces are smaller, the catalytic behaviors of Cu@Cu(1 1 1) surface are very close to the flat Cu(1 1 1) surface, suggesting that the morphology of Cu substrate does not obviously affect the dehydrogenation of CH4, which accords with the reported experimental observations. As a result, the adsorbed or substituted Rh atom on Cu catalyst exhibit a better catalytic activity for CH4 dehydrogenation compared to the pure Cu catalyst, especially on Rh-adsorbed Cu catalyst, we can conclude that the potential of synthesizing high-quality graphene with the help of Rh on Cu foils may be carried out at relatively low

  10. CH{sub 4} dehydrogenation on Cu(1 1 1), Cu@Cu(1 1 1), Rh@Cu(1 1 1) and RhCu(1 1 1) surfaces: A comparison studies of catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Riguang; Duan, Tian [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Ling, Lixia [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Research Institute of Special Chemicals, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Wang, Baojun, E-mail: wangbaojun@tyut.edu.cn [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

    2015-06-30

    Highlights: • Adsorbed Rh atom on Cu catalyst exhibits better catalytic activity for CH{sub 4} dehydrogenation. • The adsorbed Rh atom is the reaction active center for CH{sub 4} dehydrogenation. • The morphology of Cu substrate has negligible effect on CH{sub 4} dehydrogenation. - Abstract: In the CVD growth of graphene, the reaction barriers of the dehydrogenation for hydrocarbon molecules directly decide the graphene CVD growth temperature. In this study, density functional theory method has been employed to comparatively probe into CH{sub 4} dehydrogenation on four types of Cu(1 1 1) surface, including the flat Cu(1 1 1) surface (labeled as Cu(1 1 1)) and the Cu(1 1 1) surface with one surface Cu atom substituted by one Rh atom (labeled as RhCu(1 1 1)), as well as the Cu(1 1 1) surface with one Cu or Rh adatom (labeled as Cu@Cu(1 1 1) and Rh@Cu(1 1 1), respectively). Our results show that the highest barrier of the whole CH{sub 4} dehydrogenation process is remarkably reduced from 448.7 and 418.4 kJ mol{sup −1} on the flat Cu(1 1 1) and Cu@Cu(1 1 1) surfaces to 258.9 kJ mol{sup −1} on RhCu(1 1 1) surface, and to 180.0 kJ mol{sup −1} on Rh@Cu(1 1 1) surface, indicating that the adsorbed or substituted Rh atom on Cu catalyst can exhibit better catalytic activity for CH{sub 4} complete dehydrogenation; meanwhile, since the differences for the highest barrier between Cu@Cu(1 1 1) and Cu(1 1 1) surfaces are smaller, the catalytic behaviors of Cu@Cu(1 1 1) surface are very close to the flat Cu(1 1 1) surface, suggesting that the morphology of Cu substrate does not obviously affect the dehydrogenation of CH{sub 4}, which accords with the reported experimental observations. As a result, the adsorbed or substituted Rh atom on Cu catalyst exhibit a better catalytic activity for CH{sub 4} dehydrogenation compared to the pure Cu catalyst, especially on Rh-adsorbed Cu catalyst, we can conclude that the potential of synthesizing high-quality graphene with the

  11. Activation of the C-H bond: catalytic hydroxylation of hydrocarbons by new cobaltic alkylperoxydic complexes; selective and catalytic cycloalkane dehydrogenation in presence of uranium for hydrogen transfer

    International Nuclear Information System (INIS)

    The aim of the thesis is to improve efficiency and selectivity of chemical reactions for alkane transformations. In the first part decomposition of hydroperoxides and hydrocarbon hydroxylation by cobalt complexes is studied. In the second part cycloalkanes are dehydrogenated into aromatics with a Pt catalyst, trapping hydrogen by uranium. Uranium hydride UH3 can yield very pure hydrogen at reasonable temperature

  12. Catalytic and surface oxidation processes on transition metal surfaces

    OpenAIRE

    Jaatinen, Sampsa

    2007-01-01

    Transition metals are technologically important catalytic materials. The transition metal catalysts are used for example in petroleum and fertilizer industry. In the car industry the catalytic materials are used in the catalytic converters. Because of the industrial importance the catalytic metals have been widely studied throughout the past decades. Nonetheless, the oxidation mechanisms of small molecules and the effect of alloying to catalytic properties of metals are not fully understood. ...

  13. Modeling-based optimization of a fixed-bed industrial reactor for oxidative dehydrogenation of propane

    Institute of Scientific and Technical Information of China (English)

    Ali Darvishi; Razieh Davand; Farhad Khorasheh; Moslem Fattahi

    2016-01-01

    An industrial scale propylene production via oxidative dehydrogenation of propane (ODHP) in multi-tubular re-actors was modeled. Multi-tubular fixed-bed reactor used for ODHP process, employing 10000 of smal diameter tubes immersed in a shel through a proper coolant flows. Herein, a theory-based pseudo-homogeneous model to describe the operation of a fixed bed reactor for the ODHP to correspondence olefin over V2O5/γ-Al2O3 catalyst was presented. Steady state one dimensional model has been developed to identify the operation parameters and to describe the propane and oxygen conversions, gas process and coolant temperatures, as well as other pa-rameters affecting the reactor performance such as pressure. Furthermore, the applied model showed that a double-bed multitubular reactor with intermediate air injection scheme was superior to a single-bed design due to the increasing of propylene selectivity while operating under lower oxygen partial pressures resulting in propane conversion of about 37.3%. The optimized length of the reactor needed to reach 100%conversion of the oxygen was theoretically determined. For the single-bed reactor the optimized length of 11.96 m including 0.5 m of inert section at the entrance region and for the double-bed reactor design the optimized lengths of 5.72 m for the first and 7.32 m for the second reactor were calculated. Ultimately, the use of a distributed oxygen feed with limited number of injection points indicated a significant improvement on the reactor performance in terms of propane conversion and propylene selectivity. Besides, this concept could overcome the reactor run-away temperature problem and enabled operations at the wider range of conditions to obtain enhanced propyl-ene production in an industrial scale reactor.

  14. Vanadium Oxide Supported on MSU-1 as a Highly Active Catalyst for Dehydrogenation of Isobutane with CO2

    OpenAIRE

    Guosong Sun; Qingze Huang; Shiyong Huang; Qiuping Wang; Huiquan Li; Haitao Liu; Shijie Wan; Xuewang Zhang; Jinshu Wang

    2016-01-01

    Vanadium oxide supported on MSU-1, with VOx loading ranging from 2.5 to 17.5 wt. %, was developed as a highly active catalyst in dehydrogenation of isobutane with CO2. The obtained catalysts of VOx/MSU-1 were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, and H2-temperature programmed reduction (H2-TPR) methods and the results showed that the large surface area of MSU-1 was favorable for the dispersion of VOx species and the optimal loading of VOx was 12.0 wt. %. Meanwhil...

  15. Mechanistic and kinetic analysis of the oxidative dehydrogenation of ethane via novel supported alkali chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.; Veen, A.C. van; Lercher, J.A. [Technische Universitaet Muenchen (Germany). Catalysis Research Center

    2013-11-01

    The oxidative dehydrogenation of ethane over advanced catalysts is promising to selectively produce ethylene, an essential building block for the chemical industry. In this way, ethane from shale gas can be efficiently valorized. Supported alkali chloride catalysts are investigated in this work. Essential feature of those materials is the presence of a solid core (magnesium oxide in part doped with Dy{sub 2}O{sub 3}) covered under reaction conditions with a molten alkali chloride shell. It is shown that especially the lowered melting point of eutectic mixtures of LiCl with other alkali/alkaline earth metals is the key to taylor highly efficient materials. Elucidating the ODH reaction mechanism is essential to understand the reactivity of this novel catalyst class and provides the basis for improving performances. Information about elementary steps and the rate determining step were extracted from kinetic measurements, both in steady state and in transient configuration. Furthermore, isotopic labelling studies were performed, i.e. SSITKA studies and temperature programmed isotopic exchange experiments. Step experiments showed a significant oxygen uptake by the catalysts. Retained oxygen reacted quantitatively with ethane at nearly 100% selectivity to ethylene and conversion rates were comparable with rates observed during steady state operation. Thus, chemically bound oxygen in the melt is the active and selective intermediate in the ODH. Therefore, it is required to consider an intermediate and the activation is concluded to relate to the oxygen dissociation. The total concentration of stored oxygen can be correlated to the steady-state activity, while the viscosity of the melts mainly influences the selectivity towards ethene. Properties of the solid core impact on the catalyst efficiency suggesting that the oxygen species forms at the interface between support and overlayer. The quantity of retained oxygen additionally depends on the properties of the chloride

  16. Ru-N-C Hybrid Nanocomposite for Ammonia Dehydrogenation: Influence of N-doping on Catalytic Activity

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Bich Hien

    2015-06-01

    Full Text Available For application to ammonia dehydrogenation, novel Ru-based heterogeneous catalysts, Ru-N-C and Ru-C, were synthesized via simple pyrolysis of a mixture of RuCl3·6H2O and carbon black with or without dicyandiamide as a nitrogen-containing precursor at 550 °C. Characterization of the prepared Ru-N-C and Ru-C catalysts via scanning transmission electron microscopy, in conjunction with energy dispersive X-ray spectroscopy, indicated the formation of hollow nanocomposites in which the average sizes of the Ru nanoparticles were 1.3 nm and 5.1 nm, respectively. Compared to Ru-C, the Ru-N-C nanocomposites not only proved to be highly active for ammonia dehydrogenation, giving rise to a NH3 conversion of >99% at 550 °C, but also exhibited high durability. X-ray photoelectron spectroscopy revealed that the Ru active sites in Ru-N-C were electronically perturbed by the incorporated nitrogen atoms, which increased the Ru electron density and ultimately enhanced the catalyst activity.

  17. Preparation and Catalytic Oxidation Activity on 2-mercaptoethanol of a Novel Catalytic Cellulose Fibres

    Institute of Scientific and Technical Information of China (English)

    YAO Yu-yuan; LI Ying-jie; CHEN Wen-xing; Lü Wang-yang; Lü Su-fang; XU Min-hong; LIU Fan

    2007-01-01

    Cobalt tetra(N-carbonylacylic) aminophthalocyanine was supported on cellulose fibres by graft reaction to obtain a novel polymer catalyst, catalytic cellulose fibres (CCF),and the optimal supporting conditions were pH = 6, 80℃,t = 120 min. The catalytic oxidation activity of CCF towards oxidation of 2-mereaptoethanol (MEA) in aqueous solution was investigated. The experimental results demonstrated that CCF had good catalytic oxidation activity on MEA at room temperature, causing no secondary pollution and remaining efficient for the repetitive tests with no obvious decrease of catalytic activity.

  18. Methanol Oxidative Dehydrogenation on Oxide Catalysts: Molecular and Dissociative Routes and Hydrogen Addition Energies as Descriptors of Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Deshlahra, Prashant; Iglesia, Enrique

    2014-11-13

    The oxidative dehydrogenation (ODH) of alkanols on oxide catalysts is generally described as involving H-abstraction from alkoxy species formed via O–H dissociation. Kinetic and isotopic data cannot discern between such routes and those involving kinetically-relevant H-abstraction from undissociated alkanols. Here, we combine such experiments with theoretical estimates of activation energies and entropies to show that the latter molecular routes prevail over dissociative routes for methanol reactions on polyoxometalate (POM) clusters at all practical reaction temperatures. The stability of the late transition states that mediate H-abstraction depend predominantly on the stability of the O–H bond formed, making H-addition energies (HAE) accurate and single-valued descriptors of reactivity. Density functional theory-derived activation energies depend linearly on HAE values at each O-atom location on clusters with a range of composition (H3PMo12, H4SiMo12, H3PW12, H4PV1Mo11, and H4PV1W11); both barriers and HAE values reflect the lowest unoccupied molecular orbital energy of metal centers that accept the electron and the protonation energy of O-atoms that accept the proton involved in the H-atom transfer. Bridging O-atoms form O–H bonds that are stronger than those of terminal atoms and therefore exhibit more negative HAE values and higher ODH reactivity on all POM clusters. For each cluster composition, ODH turnover rates reflect the reactivity-averaged HAE of all accessible O-atoms, which can be evaluated for each cluster composition to provide a rigorous and accurate predictor of ODH reactivity for catalysts with known structure. These relations together with oxidation reactivity measurements can then be used to estimate HAE values and to infer plausible structures for catalysts with uncertain active site structures.

  19. Surface-inspired molecular vanadium oxide catalysts for the oxidative dehydrogenation of alcohols: evidence for metal cooperation and peroxide intermediates.

    Science.gov (United States)

    Werncke, C Gunnar; Limberg, Christian; Knispel, Christina; Mebs, Stefan

    2011-10-17

    On the basis that thiacalix[4]arene (H(4)T4A) complex (PPh(4) )(2) [H(2)T4A(VO(2))](2) (Ia) was found to be an adequate functional model for surface species occurring on vanadium oxide based catalysts and itself catalyses the oxidative dehydrogenation (ODH) of alcohols, an analogue containing 2,2'-thiobis(2,4-di-tert-butylphenolate), (S)L(2-), as ligand, namely, (PPh(4))(2)[(S)LVO(2)](2) (II) was investigated in the same context. Despite the apparent similarity of Ia and II, studies on II revealed several novel insights, which are also valuable in connection with surfaces of vanadia catalysts: 1) For Ia and II similar turnover numbers (TONs) were found for the ODH of activated alcohols, which indicates that the additional OH units inherent to Ia do not contribute particularly to the activity of this complex, for instance, through prebinding of the alcohol. 2) On dissolution II enters into an equilibrium with a monomeric form, which is the predominant species in solution; nevertheless, ODH proceeds exclusively at the dimeric form, and this stresses the need for cooperation of two vanadium centres. 3) By omitting O(2) from the system during the oxidation of 9-fluorenol, the reduced form of the catalyst could be isolated and fully characterised (including single-crystal X-ray analysis). The corresponding intermediate had been elusive in case of thiacalixarene system Ia. 4) Reoxidation was found to proceed via a peroxide intermediate that also oxidises one alcohol equivalent. As the peroxide can also perform mono- and dioxygenation of the thioether group in II, after a number of turnovers the active catalyst contains a sulfone group. The reduced form of this ultimate catalyst was also isolated and structurally characterised. Possible implications of 1)-4) for the function of heterogeneous vanadia catalysts are discussed. PMID:21915928

  20. Ni-M-O (M=Sn, Ti and W) catalysts prepared from dry mixing method for oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2016-03-25

    A new generation of Ni-Sn-O, Ni-Ti-O, and Ni-W-O catalysts has been prepared by a solid state grinding method. In each case the doping metal varied from 2.5% to 20%. These catalysts exhibited higher activity and selectivity for ethane oxidative dehydrogenation (ODH) than conventionally prepared mixed oxides. Detailed characterisation was achieved using XRD, N2 adsorption, H2-TPR, SEM, TEM, and HAADF-STEM in order to study the detailed atomic structure and textural properties of the synthesized catalysts. Two kinds of typical structures are found in these mixed oxides, which are (major) “NixMyO” (M = Sn, Ti or W) solid solution phases (NiO crystalline structure with doping atom incorporated in the lattice) and (minor) secondary phases (SnO2, TiO2 or WO3). The secondary phase exists as a thin layer around small “NixMyO” particles, lowering the aggregation of nanoparticles during the synthesis. DFT calculations on the formation energies of M-doped NiO structures (M = Sn, Ti, W) clearly confirm the thermodynamic feasibility of incorporating these doping metals into NiO struture. The incorporation of doping metals into the NiO lattice decreases the number of holes (h+) localized on lattice oxygen (O2- + h+ ➔ O●-), which is the main reason for the improved catalytic performance (O●- is known to favor complete ethane oxidation to CO2). The high efficiency of ethylene production achieved in these particularly prepared mixed oxide catalysts indicates that the solid grinding method could serve as a general and practical approach for the preparation of doped NiO based catalysts.

  1. Cluster-derived Ir-Sn/SiO2 catalysts for the catalytic dehydrogenation of propane: A spectroscopic study

    KAUST Repository

    Gallo, Alessandro

    2013-01-01

    Ir-Sn bimetallic silica-based materials have been prepared via deposition of the molecular organometallic clusters (NEt4)2[Ir 4(CO)10(SnCl3)2] and NEt 4[Ir6(CO)15(SnCl3)] or via deposition of Sn organometallic precursor Sn(n-C4H9) 4 onto pre-formed Ir metal particles. These solids possess promising properties, in terms of selectivity, as catalysts for propane dehydrogenation to propene. Detailed CO-adsorption DRIFTS, XANES and EXAFS characterization studies have been performed on these systems in order to compare the structural and electronic evolution of systems in relation to the nature of the Ir-Sn bonds present in the precursor compounds and to propose a structural model of the Ir-Sn species present at the silica surface of the final catalyst. © 2013 The Royal Society of Chemistry.

  2. New Insights into the Oxidative Dehydrogenation of Propane and Ethane on SupportedVanadium Oxide Catalysts

    OpenAIRE

    Dinse, Arne

    2009-01-01

    Die vorliegende Arbeit gewährt einen tiefer gehenden Einblick in die oxidative Dehydrierung von Propan (ODP) und Ethan (ODE) an unterschiedlich geträgerten Vanadiumoxid-Katalysatoren. Zunächst wurde ein starker Einfluss des Trägermaterials (CeO2, TiO2, Al2O3, ZrO2 and SiO2) auf Selektivität, Aktivierungsenergie und Aktivität der ODP festgestellt. Aufgrund ihres unterschiedlichen katalytischen Verhaltens wurden TiO2, -Al2O3 and SiO2 (SBA-15) geträgerte Katalysatoren, bevor und nachdem diese f...

  3. Phase transformations of the FePO4 catalyst in the oxidative dehydrogenation to form an alkyl methacrylate

    Science.gov (United States)

    Khan, F. B.; Bharuth-Ram, K.; Friedrich, H. B.

    2010-04-01

    A phase specific iron orthophosphate catalyst, FePO4, was synthesized and subjected to oxidative dehydrogenation reactions to form an alkyl methacrylate. The phases of the catalyst, before and after the reactions, were characterized by Mössbauer spectroscopy. The Mössbauer spectra show the change of the catalyst precursor FePO4, tridymite-like phase (tdm), to the reduced form, iron(II) pyrophosphate, Fe2P2O7, and thereafter the phase change is governed by the temperatures of oxidation. X-ray diffraction and Mössbauer measurements on the spent catalyst, after using organic and water co-feeds, show a transformation of the catalyst to a mixture of phases which are condition specific.

  4. Water co-catalyzed selective dehydrogenation of methanol to formaldehyde and hydrogen

    Science.gov (United States)

    Shan, Junjun; Lucci, Felicia R.; Liu, Jilei; El-Soda, Mostafa; Marcinkowski, Matthew D.; Allard, Lawrence F.; Sykes, E. Charles H.; Flytzani-Stephanopoulos, Maria

    2016-08-01

    The non-oxidative dehydrogenation of methanol to formaldehyde is considered a promising method to produce formaldehyde and clean hydrogen gas. Although Cu-based catalysts have an excellent catalytic activity in the oxidative dehydrogenation of methanol, metallic Cu is commonly believed to be unreactive for the dehydrogenation of methanol in the absence of oxygen adatoms or oxidized copper. Herein we show that metallic Cu can catalyze the dehydrogenation of methanol in the absence of oxygen adatoms by using water as a co-catalyst both under realistic reaction conditions using silica-supported PtCu nanoparticles in a flow reactor system at temperatures below 250 °C, and in ultra-high vacuum using model PtCu(111) catalysts. Adding small amounts of isolated Pt atoms into the Cu surface to form PtCu single atom alloys (SAAs) greatly enhances the dehydrogenation activity of Cu. Under the same reaction conditions, the yields of formaldehyde from PtCu SAA nanoparticles are more than one order of magnitude higher than on the Cu nanoparticles, indicating a significant promotional effect of individual, isolated Pt atoms. Moreover, this study also shows the unexpected role of water in the activation of methanol. Water, a catalyst for methanol dehydrogenation at low temperatures, becomes a reactant in the methanol steam reforming reactions only at higher temperatures over the same metal catalyst.

  5. Influence of the Pressure on the Product Distribution in the Oxidative Dehydrogenation of Propane over a Ga2O3/MoO3 Catalyst

    OpenAIRE

    Kotanjac, Zeljko S.; Niederer, John P.M.; Versteeg, Geert F.

    2007-01-01

    The yields and selectivities in both the catalyzed and non-catalyzed oxidative dehydrogenation of propane were found to increase with increasing pressure. The results showed that the maximum yields of valuable ODH products could be obtained by adjusting only reactants' partial pressure, while keeping their ratio constant.

  6. Graphene-based materials in catalytic wet peroxide oxidation

    OpenAIRE

    Gomes, Helder; Ribeiro, Rui; Pastrana-Martínez, Luisa; Figueiredo, José; Faria, Joaquim; Silva, Adrián

    2014-01-01

    In catalytic wet peroxide oxidation (CWPO),an advanced oxidation process, hydrogen peroxide (H2O2) is decomposed catalytically giving rise to hydroxyl radicals (HO•).These radicals, exhibiting high oxidizing potential, serve as effective and non selective species for the degradation of several organic pollutants in liquid phase. Since the report of Lücking et al. [1], carbon materials have been explored as catalysts for CWPO[2]. Recent reports address process intensification issues, br...

  7. The effect of mixed HCl-KCl competitive adsorbate on Pt adsorption and catalytic properties of Pt-Sn/Al2O3 catalysts in propane dehydrogenation

    Science.gov (United States)

    Zangeneh, Farnaz Tahriri; Taeb, Abbas; Gholivand, Khodayar; Sahebdelfar, Saeed

    2015-12-01

    The effect of competitive adsorbate concentration and combination on the adsorption of H2PtCl6 onto γ-Al2O3 in the preparation and performance of PtSnK/γ-Al2O3 catalyst for propane dehydrogenation was investigated. The catalysts were prepared by sequential impregnation of Sn and Pt precursors. The effect of competitor concentration on Pt adsorption was studied by using hydrochloric acid (0.1-0.3 M) and the effect of pH was studied by using KCl/HCl mixtures at constant (0.1 M) total chloride ion concentration. The catalysts were characterized by nitrogen adsorption/desorption, XRD, XRF, SEM and CO chemisorption. The catalytic performance tests were carried out in a fixed-bed quartz reactor under kinetic controlled condition for proper catalyst screening. It was found that the corrosive competitor HCl could be partially substituted with KCl without appreciable impact on catalyst performance with the advantage of lower acid attack on the support and reduced leaching of the deposited tin. A model based on initial concentration and uptake of the adsorbates was developed to obtain the adsorption parameters. Values of 890 μmol/g and 600 lit/mol were obtained for adsorption site concentration of the tin-impregnated support and equilibrium constant for Pt adsorption, respectively, for HCl concentration range of 0.1-0.3 M.

  8. Catalytic partial oxidation of pyrolysis oils

    Science.gov (United States)

    Rennard, David Carl

    2009-12-01

    This thesis explores the catalytic partial oxidation (CPO) of pyrolysis oils to syngas and chemicals. First, an exploration of model compounds and their chemistries under CPO conditions is considered. Then CPO experiments of raw pyrolysis oils are detailed. Finally, plans for future development in this field are discussed. In Chapter 2, organic acids such as propionic acid and lactic acid are oxidized to syngas over Pt catalysts. Equilibrium production of syngas can be achieved over Rh-Ce catalysts; alternatively mechanistic evidence is derived using Pt catalysts in a fuel rich mixture. These experiments show that organic acids, present in pyrolysis oils up to 25%, can undergo CPO to syngas or for the production of chemicals. As the fossil fuels industry also provides organic chemicals such as monomers for plastics, the possibility of deriving such species from pyrolysis oils allows for a greater application of the CPO of biomass. However, chemical production is highly dependent on the originating molecular species. As bio oil comprises up to 400 chemicals, it is essential to understand how difficult it would be to develop a pure product stream. Chapter 3 continues the experimentation from Chapter 2, exploring the CPO of another organic functionality: the ester group. These experiments demonstrate that equilibrium syngas production is possible for esters as well as acids in autothermal operation with contact times as low as tau = 10 ms over Rh-based catalysts. Conversion for these experiments and those with organic acids is >98%, demonstrating the high reactivity of oxygenated compounds on noble metal catalysts. Under CPO conditions, esters decompose in a predictable manner: over Pt and with high fuel to oxygen, non-equilibrium products show a similarity to those from related acids. A mechanism is proposed in which ethyl esters thermally decompose to ethylene and an acid, which decarbonylates homogeneously, driven by heat produced at the catalyst surface. Chapter 4

  9. Intrinsic kinetics of oxidative dehydrogenation of propane in the presence of CO2 over Cr/MSU-1 catalyst

    Institute of Scientific and Technical Information of China (English)

    Haitao Liu; Zhao Zhang; Huiquan Li; Qingze Huang

    2011-01-01

    The intrinsic kinetics of oxidative dehydrogenation of propane with CO2 has been investigated over Cr/MSU-1 catalyst in a fixed bed reactor.Without limitations of both internal and external diffusion, intrinsic kinetic data were obtained under the following conditions: 490-530 C,space velocity of 3600-6000 mL·h-l·g-1 and 3/1 molar ratio for CO2/C3H8 under normal pressure. Based on Langmuir-Hinshelwood mechanism, the kinetic models were established, and they were validated by statistical analysis. The parameters were estimated using Simplex Method combined with Universal Global Optimization Algorithm. The model, taking the surface reaction process as the rate-determining step,is the best one in agreement with the experimental data.

  10. Structural, electrical and catalytic properties of ion-implanted oxides

    OpenAIRE

    Hassel, van, E Edwin; Burggraaf, A.J.

    1989-01-01

    The potential application of ion implantation to modify the surfaces of ceramic materials is discussed. Changes in the chemical composition and microstructure result in important variations of the electrical and catalytic properties of oxides.

  11. Catalytic oxidative conversion of alkanes to olefines and oxygenates

    Energy Technology Data Exchange (ETDEWEB)

    Baerns, M. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

    1998-12-31

    All of the direct reaction schemes described and the corresponding process schemes are still in an exploratory state. Ethylene by oxidative coupling of methane could become competitive if process schemes are developed with significantly less expenditures for separation of the product from unconverted feed. No encouragement for formaldehyde from methane can be presently derived from the existing knowledge. Liquid-phase oxidation of methane to methanol appears to be attractive but no final judgement is possible at present. Oxidative dehydrogenation of ethylene and propane look promising although further catalyst improvement is required. Acetic acid from ethane and acrylonitrile from propane have a certain potential as an alternative to present technology. The outlook for acrolein and acrylic acid from propane is less favourable; new concepts for catalyst design are necessary. (orig.)

  12. Final Report, "Molecular Design of Hydrocarbon Oxidation Catalytic Processes"

    Energy Technology Data Exchange (ETDEWEB)

    Professor Francisco Zaera

    2007-08-09

    production of small amounts of ethylene and water, most likely via the concerted decomposition or disproportionation of the adsorbed molecular species. The bulk of the 2-iodoethanol decomposes at about 150 K via an initial carbon-iodine scission to form –O(H)CH2CH2– (~80%) and 2-hydroxyethyl (~20%) intermediates. Two competing reactions are involved with the subsequent conversion of the 2-hydroxyethyl species around 160 K, a reductive elimination with surface hydrogen to yield ethanol, and a β-H elimination to surface vinyl alcohol. The –O(H)CH2CH2–, on the other hand, dehydrogenates to a –OCH2CH2– oxametallacycle species about the same temperature. Both 2-hydroxyethyl and oxametallacycle species tautomerize to acetaldehyde, around 210 K and above 250 K, respectively, and some of that acetaldehyde desorbs while the rest decomposes to hydrogen and carbon monoxide. We contend that a better understanding of the surface chemistry of oxygen-containing surfaces can lead to better selectivities in catalysis. This is arguably the most important issue in the field of catalysis in the near future, and one that impacts several technologies of interest to DOE such as the manufacturing of speciality chemicals and the control and removal of pollutants. Additional work was performed on the characterization of the chemistry of methyl and methylene adsorbed species on oxygen-treated nickel surfaces. Complex chemistry was observed involving not only hydrogenation and dehydrogenation steps, but also C-C couplings and methylene insertions to produce heavier hydrocarbons, and oxygen insertion reactions that yield oxygenates. Finally, a dual titration technique employing xenon and a chemically sensitive probe was developed to identify minority catalytic sites on oxide surfaces. In the case of oxygen-treated Ni(110) single crystals, it was found that both hydrogen transfer with adsorbed water or ammonia and certain hydrocarbon hydrogenation reactions take place at the end of the

  13. Oxidative Dehydrogenation of Cyclohexane on Cobalt Oxide (Co3O4) Nanoparticles: The Effect of Particle Size on Activity and Selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Tyo, Eric C.; Yin, Chunrong; Di Vece, Marcel; Qian, Qiang; Kwon, Gihan; Lee, Sungsik; Lee, Byeongdu; DeBartolo, Janae E.; Seifert, Sönke; Winans, Randall E.; Si, Rui; Ricks, Brian; Goergen, Simone; Rutter, Matthew; Zugic, Branko; Flytzani-Stephanopoulos, Maria; Wang, Zhi Wei; Palmer, Richard E.; Neurock, Matthew; Vajda, Stefan

    2012-10-02

    The oxidative dehydrogenation of cyclohexane by cobalt oxide nanoparticles was studied via temperature programmed reaction combined with in situ grazing incidence X-ray absorption spectroscopy and grazing incidence small-angle X-ray scattering and theoretical calculations on model Co3O4 substrates. Both 6 and 12 nm Co3O4 nanoparticles were made through a surfactant-free preparation and dispersed on an Al2O3 surface formed by atomic layer deposition. Under reaction conditions the nanoparticles retained their oxidation state and did not sinter. They instead underwent an assembly/disassembly process and could reorganize within their assemblies. The selectivity of the catalyst was found to be size- and temperature-dependent, with larger particles preferentially producing cyclohexene at lower temperatures and smaller particles predominantly resulting in benzene at higher temperatures. The mechanistic features thought to control the oxidative dehydrogenation of cyclohexane and other light alkanes on cobalt oxide were established by carrying out density functional theory calculations on the activation of propane, a surrogate model alkane, over model Co3O4 surfaces. The initial activation of the alkane (propane) proceeds via hydrogen abstraction over surface oxygen sites. The subsequent activation of the resulting alkoxide intermediate occurs at a second surface oxygen site to form the alkene (propene) which then desorbs from the surface. Hydroxyl recombination results in the formation of water which desorbs from the surface. Finally, oxygen is necessary to regenerate the surface oxygen sites, catalyze C–H activation steps, and minimize catalyst degradation.

  14. 不同孔道结构的氧化硅负载钒氧化物催化丙烷氧化脱氢%Propane Oxidative Dehydrogenation over Vanadia Catalysts Supported on Silicas with Different Pore Structures

    Institute of Scientific and Technical Information of China (English)

    缪建文; 宋国华; 范以宁

    2009-01-01

    The state and reactivity of surface oxygen species of mesoporous silica-supported vanadium oxide catalysts for oxidative dehy- drogenation of propane have been investigated by microreactor tests combined with in-situ electron spin resonance, tempera- ture-programmed surface reaction, and ultraviolet-visible diffuse reflectance spectroscopy. The pore diameter of the SBA-15, MCM-41, and silica gel supports exert great influences on the dispersion state of VO_x species and the catalytic properties of the supported vanadium oxide catalysts. The SBA-15-supported vanadium oxide catalyst has the highest selectivity for propylene because of its larger pore diameter and higher surface area. Surface lattice oxygen species of the VOx/SBA-15 catalyst are main active species for oxidative dehydrogenation of propane to propylene. Highly dispersed VO_x species have high catalytic reactivity for oxidative dehydrogenation of propane. CO_2 can regen-erate the lattice oxygen species of supported vanadium oxide catalysts. The high propylene selectivity for oxidative dehydrogenation of pro- pane by CO_2 on supported vanadium oxide catalysts is related to weaker oxidizing effect of CO_2, which inhibits the direct C_3H_8 oxidation and the consecutive oxidation of C_3H_6 to CO_x.%采用固定床微型反应装置,结合催化剂的原位电子自旋共振光谱、程序升温表面反应和紫外漫反射光谱等技术,研究了丙烷氧化脱氢的介孔氧化硅负载钒氧化物催化剂的性能和表面氧物种的状态及其反应性.结果表明,催化剂载体孔结构是影响钒氧物种分散状态乃至催化性能的一个重要因素.SBA-15负载钒氧化物催化剂因具有较大的比表面积和较大的孔径,不仅具有较高的丙烷氧化脱氢催化活性,而且具有较高的丙烯选择性.复合型钒氧化物催化剂表面与V离子相连的晶格氧物种是丙烷氧化脱氢牛成内烯的主要活性物种,载体表面高度分散的钒氧物种具有较

  15. Influence of the pressure on the product distribution in the oxidative dehydrogenation of propane over a Ga2O3/MoO3 catalystInfluence of the pressure on the product distribution in the oxidative dehydrogenation of propane over a Ga2O3/MoO3 catalyst

    NARCIS (Netherlands)

    Kotanjac, Z. S.; Niederer, J. P. M.; Versteeg, G. F.

    2007-01-01

    The yields and selectivities in both the catalyzed and non-catalyzed oxidative dehydrogenation of propane were found to increase with increasing pressure. The results showed that the maximum yields of valuable ODH products could be obtained by adjusting only reactants' partial pressure, while keepin

  16. Identifying Different Types of Catalysts for CO2 Reduction by Ethane through Dry Reforming and Oxidative Dehydrogenation.

    Science.gov (United States)

    Porosoff, Marc D; Myint, Myat Noe Zin; Kattel, Shyam; Xie, Zhenhua; Gomez, Elaine; Liu, Ping; Chen, Jingguang G

    2015-12-14

    The recent shale gas boom combined with the requirement to reduce atmospheric CO2 have created an opportunity for using both raw materials (shale gas and CO2 ) in a single process. Shale gas is primarily made up of methane, but ethane comprises about 10 % and reserves are underutilized. Two routes have been investigated by combining ethane decomposition with CO2 reduction to produce products of higher value. The first reaction is ethane dry reforming which produces synthesis gas (CO+H2 ). The second route is oxidative dehydrogenation which produces ethylene using CO2 as a soft oxidant. The results of this study indicate that the Pt/CeO2 catalyst shows promise for the production of synthesis gas, while Mo2 C-based materials preserve the CC bond of ethane to produce ethylene. These findings are supported by density functional theory (DFT) calculations and X-ray absorption near-edge spectroscopy (XANES) characterization of the catalysts under in situ reaction conditions. PMID:26554872

  17. Synthesis of Pt–Pd Core–Shell Nanostructures by Atomic Layer Deposition: Application in Propane Oxidative Dehydrogenation to Propylene

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yu; Liu, Bin; Lu, Junling; Lobo-Lapidus, Rodrigo J.; Wu, Tianpin; Feng, Hao; Xia, Xiaoxing; Mane, Anil U.; Libera, Joseph A.; Greeley, Jeffrey P.; Miller, Jeffrey T.; Elam, Jeffrey W.

    2012-08-20

    Atomic layer deposition (ALD) was employed to synthesize supported Pt–Pd bimetallic particles in the 1 to 2 nm range. The metal loading and composition of the supported Pt–Pd nanoparticles were controlled by varying the deposition temperature and by applying ALD metal oxide coatings to modify the support surface chemistry. High-resolution scanning transmission electron microscopy images showed monodispersed Pt–Pd nanoparticles on ALD Al2O3- and TiO2-modified SiO2 gel. X-ray absorption spectroscopy revealed that the bimetallic nanoparticles have a stable Pt-core, Pd-shell nanostructure. Density functional theory calculations revealed that the most stable surface configuration for the Pt–Pd alloys in an H2 environment has a Pt-core, Pd-shell nanostructure. Finally, in comparison to their monometallic counterparts, the small Pt–Pd bimetallic core–shell nanoparticles exhibited higher activity in propane oxidative dehydrogenation as compared to their physical mixture.

  18. Photocatalytic Ethanol Oxidative Dehydrogenation over Pt/TiO2: Effect of the Addition of Blue Phosphors

    Directory of Open Access Journals (Sweden)

    J. J. Murcia

    2012-01-01

    Full Text Available Ethanol oxidative dehydrogenation over Pt/TiO2 photocatalyst, in the presence and absence of blue phosphors, was performed. The catalyst was prepared by photodeposition of Pt on sulphated TiO2. This material was tested in a gas-solid photocatalytic fluidized bed reactor at high illumination efficiency. The effect of the addition of blue phosphors into the fluidized bed has been evaluated. The synthesized catalysts were extensively characterized by different techniques. Pt/TiO2 with a loading of 0.5 wt% of Pt appeared to be an active photocatalyst in the selective partial oxidation of ethanol to acetaldehyde improving its activity and selectivity compared to pure TiO2. In the same way, a notable enhancement of ethanol conversion in the presence of the blue phosphors has been obtained. The blue phosphors produced an increase in the level of ethanol conversion over the Pt/TiO2 catalyst, keeping at the same time the high selectivity to acetaldehyde.

  19. Catalytic abatement of nitrous oxide from nitric and production

    NARCIS (Netherlands)

    Oonk, J.

    1998-01-01

    Nitric acid production is identified as a main source of nitrous oxide. Options for emission reduction however are not available. TNO and Hydro Agri studied the technological and economic feasibility of catalytic decomposition of nitrous oxide in nitric acid tail-gases. Although in literature promis

  20. Catalytic oxidative cracking of hexane as a route to olefins

    NARCIS (Netherlands)

    Boyadjian, Cassia; Lefferts, Leon; Seshan, K.

    2010-01-01

    Catalytic oxidative cracking of naphtha is conceptually an alternative process to steam cracking. The performance of sol–gel synthesized Li/MgO in oxidative cracking of hexane as a model compound of naphtha, has been studied and compared to that of conventionally prepared catalyst. At a temperature

  1. CATALYTIC HYDROGENATION AND OXIDATION OF BIOMASS-DERIVED LEVULINIC ACID

    OpenAIRE

    Yan Gong; Lu Lin; Zhipei Yan

    2011-01-01

    Levulinic acid (LA), 4-oxo-pentanoic acid, is a new platform chemical with various potential uses. In this paper, catalytic hydrogenation and oxidation of levulinic acid were studied. It was shown from experiments that levulinic acid can be hydrogenated to γ-valerolactone (GVL) over transition metal catalysts and oxidative-decarboxylated to 2-butanone (methyl-ethyl-ketone, MEK) and methyl-vinyl-ketone (MVK) by cupric oxide (CuO), cupric oxide/cerium oxide (CuO/CeO2), cupric oxide/ alumina (Cu...

  2. CATALYTIC HYDROGENATION AND OXIDATION OF BIOMASS-DERIVED LEVULINIC ACID

    Directory of Open Access Journals (Sweden)

    Yan Gong

    2011-02-01

    Full Text Available Levulinic acid (LA, 4-oxo-pentanoic acid, is a new platform chemical with various potential uses. In this paper, catalytic hydrogenation and oxidation of levulinic acid were studied. It was shown from experiments that levulinic acid can be hydrogenated to γ-valerolactone (GVL over transition metal catalysts and oxidative-decarboxylated to 2-butanone (methyl-ethyl-ketone, MEK and methyl-vinyl-ketone (MVK by cupric oxide (CuO, cupric oxide/cerium oxide (CuO/CeO2, cupric oxide/ alumina (CuO/ Al2O3, and silver(I/ peroxydisulfate (Ag(I/S2O82-.

  3. Studies on Nitrogen Oxides Removal Using Plasma Assisted Catalytic Reactor

    Institute of Scientific and Technical Information of China (English)

    V. Ravi; Young Sun Mok; B. S. Rajanikanth; Ho-Chul Kang

    2003-01-01

    An electric discharge plasma reactor combined with a catalytic reactor was studied for removing nitrogen oxides. To understand the combined process thoroughly, discharge plasma and catalytic process were separately studied first, and then the two processes were combined for the study. The plasma reactor was able to oxidize NO to NO2 well although the oxidation rate decreased with temperature. The plasma reactor alone did not reduce the NOx (NO+NO2)level effectively, but the increase in the ratio of NO2 to NO as a result of plasma discharge led to the enhancement of NOx removal efficiency even at lower temperatures over the catalyst surface (V2O5-WOa/TiO2). At a gas temperature of 100℃, the NOx removal efficiency obtained using the combined plasma catalytic process was 88% for an energy input of 36 eV/molecule or 30 J/1.

  4. Catalytic wet Air Oxidation of o-Chlorophenol in Wastewater

    Institute of Scientific and Technical Information of China (English)

    徐新华; 汪大翬

    2003-01-01

    Catalytic wet air oxidation (CWAO) was investigated in laboratory-scale experiments for the treatment of o-chlorophenol in wastewater. Experimental results showed that wet air oxidation (WAO) process in the absence of catalyst was also effective for o-chlorophenol in wastewater treatment. Up to 80% of the initial CODCr was removed by wet air oxidation at 270℃ with twice amount of the required stoichiometric oxygen supply. At temperature of 150℃, the removal rate of CODCr was only 30%. Fe2(SO4)3, CuSO4, Cu(NO3)2 and MnSO4 exhibited high catalytic activity. Higher removal rate of CODCr was obtained by CWAO. More than 96% of the initial CODCr was removed at 270℃ and 84.6%-93.6% of the initial CODCr was removed at 150℃. Mixed catalysts had better catalytic activity for the degradation of o-chlorophenol in wastewater.

  5. Shale gas opportunities. Dehydrogenation of light alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Patcas, F.C.; Dieterle, M.; Rezai, A.; Asprion, N. [BASF SE, Ludwigshafen (Germany)

    2013-11-01

    The discovery and use of shale gas in North America has become a game changer for the chemical industry by access to a cheaper feedstock compared to conventional oil. Increased number of ethane crackers spurred increasing interest in light alkanes dehydrogenation. Several companies have announced their interest in new propane dehydrogenation units in North America. BASF is developing light alkanes dehydrogenation technologies for two decades now. BASF developed jointly with Linde the isothermal C3 dehydrogenation process. The latest dehydrogenation catalyst development at BASF focused on a supported and steam resistant Pt-Sn catalyst which yielded excellent selectivity and activity. Intense research work both internally as well as in cooperation with universities contributed to the understanding of the relationship between the surface structure and catalyst performances like activity, selectivity and coking resistance. Using such type of catalysts BASF developed an autothermal propane dehydrogenation as well as a butane dehydrogenation process. The most recent catalyst development was a dehydrogenation catalyst coated on a honeycomb monolith to improve catalyst usage and pressure drop. This will probably be the first industrial usage of catalytic monoliths in a chemical synthesis process. (orig.) (Published in summary form only)

  6. Roles of catalytic oxidation in control of vehicle exhaust emissions

    International Nuclear Information System (INIS)

    Catalytic oxidation was initially associated with the early development of catalysis and it subsequently became a part of many industrial processes, so it is not surprising it was used to remove hydrocarbons and CO when it became necessary to control these emissions from cars. Later NOx was reduced in a process involving reduction over a Pt/Rh catalyst followed by air injection in front of a Pt-based oxidation catalyst. If over-reduction of NO to NH3 took place, or if H2S was produced, it was important these undesirable species were converted to NOx and SOx in the catalytic oxidation stage. When exhaust gas composition could be kept stoichiometric hydrocarbons, CO and NOx were simultaneously converted over a single Pt/Rh three-way catalyst (TWC). With modern TWCs car tailpipe emissions can be exceptionally low. NO is not catalytically dissociated to O2 and N2 in the presence of O2, it can only be reduced to N2. Its control from lean-burn gasoline engines involves catalytic oxidation to NO2 and thence nitrate that is stored and periodically reduced to N2 by exhaust gas enrichment. This method is being modified for diesel engines. These engines produce soot, and filtration is being introduced to remove it. The exhaust temperature of heavy-duty diesels is sufficient (250-400oC) for NO to be catalytically oxidised to NO2 over an upstream platinum catalyst that smoothly oxidises soot in the filter. The exhaust gas temperature of passenger car diesels is too low for this to take place all of the time, so trapped soot is periodically burnt in O2 above 550oC. Catalytic oxidation of higher than normal amounts of hydrocarbon and CO over an upstream catalyst is used to give sufficient temperature for soot combustion with O2 to take place. (author)

  7. Alcohol Dehydrogenation with a Dual Site Ruthenium, Boron Catalyst Occurs at Ruthenium

    OpenAIRE

    Denver Guess; Williams, Travis J.; Conley, Brian L.; Brock Malinoski; Zhiyao Lu; Ana V. Flores

    2012-01-01

    The complex [(κ3-(N,N,O-py2B(Me)OH)Ru(NCMe)3]+ TfO− (1) is a catalyst for transfer dehydrogenation of alcohols, which was designed to function through a cooperative transition state in which reactivity was split between boron and ruthenium. We show here both stoichiometric and catalytic evidence to support that in the case of alcohol oxidation, the mechanism most likely involves reactivity only at the ruthenium center.

  8. Alcohol Dehydrogenation with a Dual Site Ruthenium, Boron Catalyst Occurs at Ruthenium

    Directory of Open Access Journals (Sweden)

    Denver Guess

    2012-10-01

    Full Text Available The complex [(κ3-(N,N,O-py2B(MeOHRu(NCMe3]+ TfO− (1 is a catalyst for transfer dehydrogenation of alcohols, which was designed to function through a cooperative transition state in which reactivity was split between boron and ruthenium. We show here both stoichiometric and catalytic evidence to support that in the case of alcohol oxidation, the mechanism most likely involves reactivity only at the ruthenium center.

  9. Surface and catalytic properties of doped tin oxide nanoparticles

    Science.gov (United States)

    Wang, Chien-Tsung; Lai, De-Lun; Chen, Miao-Ting

    2010-10-01

    Mixed oxides composed of Zn-Sn, Ti-Sn and V-Sn were prepared by a co-precipitation method and evaluated as catalysts for methanol oxidation in an ambient fixed-bed reactor. Surface analysis by X-ray photoelectron spectroscopy (XPS) revealed an electronic interaction between dopant and Sn atoms in the oxide structure and showed the formation of surface states associated with the dopants. Oxygen vacancies were present on the Zn-doped oxide, and the oxidation of methanol to carbon oxides was favored. The Ti-doped oxide exhibited a favorable selectivity to dimethyl ether, related to the oxygen anions near Ti centers. Vanadium dopants not only dramatically increased the catalytic activity but also promoted the partial oxidation of methanol to formaldehyde. Results demonstrate that the bridging dopant-O-Sn bond acts as active sites and influences product distribution.

  10. Visualizing the mobility of silver during catalytic soot oxidation

    DEFF Research Database (Denmark)

    Gardini, Diego; Christensen, Jakob M.; Damsgaard, Christian Danvad;

    2016-01-01

    The catalytic activity and mobility of silver nanoparticles used as catalysts in temperature programmed oxidation of soot:silver (1:5 wt:wt) mixtures have been investigated by means of flow reactor experiments and in situ environmental transmission electron microscopy (ETEM). The carbon oxidation...... mobility during the soot oxidation, and this mobility, which increases the soot/catalyst contact, is expected to be an important factor for the lower oxidation temperature. In the intimate tight contact mixture the initial dispersion of the silver particles is greater,,and the onset of mobility occurs at a...

  11. Catalytic Partial Oxidation of Biomass/Oil Mixture

    Czech Academy of Sciences Publication Activity Database

    Veselý, Václav; Hanika, Jiří; Tukač, V.; Lederer, J.; Kovač, D.

    2013-01-01

    Roč. 7, č. 10 (2013), s. 1940-1945. ISSN 1934-8983 R&D Projects: GA TA ČR TE01020080; GA MPO 2A-2TP1/024 Institutional support: RVO:67985858 Keywords : hydrocarbon oil * biomass * catalytic partial oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.davidpublishing.com/journals_info.asp?jId=1718#

  12. Trends in the Catalytic CO Oxidation Activity of Nanoparticles

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Falsig, Hanne; Larsen, Britt Hvolbæk;

    2008-01-01

    Going for gold: Density functional calculations show how gold nanoparticles are more active catalysts for CO oxidation than other metal nanoparticles. The high catalytic activity of nanosized gold clusters at low temperature is found to be related to the ability of low-coordinate metal atoms to a...

  13. Solid Waste Decontamination by Thermal Desorption and Catalytic Oxidation Methods

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga; Topka, Pavel; Soukup, Karel; Jirátová, Květa; Váňová, H.; Kaštánek, František

    2014-01-01

    Roč. 68, č. 9 (2014), s. 1279-1282. ISSN 0366-6352 R&D Projects: GA MPO FR-TI1/059 Institutional support: RVO:67985858 Keywords : thermal desorption * catalytic oxidation * soil decontamination Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.468, year: 2014

  14. Lignin Valorization using Heterogenous Catalytic Oxidation

    DEFF Research Database (Denmark)

    Melián Rodríguez, Mayra; Shunmugavel, Saravanamurugan; Kegnæs, Søren;

    The research interests in biomass conversion to fuels and chemicals has increased significantly in the last decade in view of current problems such as global warming, high oil prices, food crisis and other geopolitical scenarios. Many different reactions and processes to convert biomass into high......-value products and fuels have been proposed in the literature, giving special attention to the conversion of lignocellulosic biomass, which does not compete with food resources and is widely available as a low cost feedstock 1. Lignocellulose biomass is a complex material composed of three main fractions...... complex so different model compounds are often used to study lignin valorization. These model compounds contain the linkages present in lignin, simplifying catalytic analysis and present analytical challenges related to the study of the complicated lignin polymer and the plethora of products that could be...

  15. Operando UV-Vis spectroscopy of a catalytic solid in a pilos-scale reactor: deactivation of a CrOx/Al2O3 propane dehydrogenation catalyst

    OpenAIRE

    Sattler, J.J.H.B.; Gonzalez-Jimenez, I.D.; Mens, A.J.M.; Arias, M.J.; Visser, T.; Weckhuysen, B. M.

    2013-01-01

    A novel operando UV-Vis spectroscopic set-up has been constructed and tested for the investigation of catalyst bodies loaded in a pilot-scale reactor under relevant reaction conditions. Spatiotemporal insight into the formation and burning of coke deposits on an industrial CrOx/Al2O3 catalyst during propane dehydrogenation has been obtained.

  16. Polarographic catalytic wave of hydrogen--Parallel catalytic hydrogen wave of bovine serum albumin in thepresence of oxidants

    Institute of Scientific and Technical Information of China (English)

    过玮; 刘利民; 林洪; 宋俊峰

    2002-01-01

    A polarographic catalytic hydrogen wave of bovine serum albumin (BSA) at about -1.80 V (vs. SCE) in NH4Cl-NH3@H2O buffer is further catalyzed by such oxidants as iodate, persulfate and hydrogen peroxide, producing a kinetic wave. Studies show that the kinetic wave is a parallel catalytic wave of hydrogen, which resulted from that hydrogen ion is electrochemically reduced and chemically regenerated through oxidation of its reduction product, atomic hydrogen, by oxidants mentioned above. It is a new type of poralographic catalytic wave of protein, which is suggested to be named as a parallel catalytic hydrogen wave.

  17. Catalytic combustion over high temperature stable metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Berg, M. [TPS Termiska Processer AB, Nykoeping (Sweden)

    1996-12-31

    This thesis presents a study of the catalytic effects of two interesting high temperature stable metal oxides - magnesium oxide and manganese substituted barium hexa-aluminate (BMA) - both of which can be used in the development of new monolithic catalysts for such applications. In the first part of the thesis, the development of catalytic combustion for gas turbine applications is reviewed, with special attention to alternative fuels such as low-BTU gas, e.g. produced in an air blown gasifier. When catalytic combustion is applied for such a fuel, the primary advantage is the possibility of decreasing the conversion of fuel nitrogen to NO{sub x}, and achieving flame stability. In the experimental work, MgO was shown to have a significant activity for the catalytic combustion of methane, lowering the temperature needed to achieve 10 percent conversion by 270 deg C compared with homogeneous combustion.The reaction kinetics for methane combustion over MgO was also studied. It was shown that the heterogeneous catalytic reactions were dominant but that the catalytically initiated homogeneous gas phase reactions were also important, specially at high temperatures. MgO and BMA were compared. The latter showed a higher catalytic activity, even when the differences in activity decreased with increasing calcination temperature. For BMA, CO{sub 2} was the only product detected, but for MgO significant amounts of CO and C{sub 2}-hydrocarbons were formed. BMA needed a much lower temperature to achieve total conversion of other fuels, e.g. CO and hydrogen, compared to the temperature for total conversion of methane. This shows that BMA-like catalysts are interesting for combustion of fuel mixtures with high CO and H{sub 2} content, e.g. gas produced from gasification of biomass. 74 refs

  18. Catalytic oxidation of CS2 over atmospheric particles and oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The catalytic oxidization of CS2 over atmospheric particles and some oxide catalysts was explored through FT-IR, MS and a fixed-bed stainless steel reactor. The results show that at mospheric particles and some oxide catalysts exhibited considerable oxidizing activities for CS2 at ambient temperature. The reaction products are mainly COS and elemental sulfur, even CO2 on some catalysts. Among the catalysts, CaO has the strongest catalytic activity for oxidizing CS2. Fe2O3 is weaker than CaO. The catalytic activity for AI2O3 reduces considerably compared with the former two catalysts, and SiO2 the weakest. Atmospheric particle samples' catalytic activity is be tween Fe2O3's and AI2O3's. The atmospheric particle sample collected mainly consists of Ca(AI2Si2O8)· 4H2O, which is also the main component of cement. COS, the main product, is formed by the catalytic oxidization of CS2 with adsorbed “molecular” oxygen over the catalysts' surfaces. The concentration of adsorbed oxygen over catalysts' surfaces may be the key factor contributed to the oxidizing activity. It is indicated that CS2 could be catalytically oxidized over at mospheric particles, which induced that this reaction may be another important source of atmos pheric COS from CS2.

  19. Dehydrogenation of propane in the presence of CO{sub 2} over polyacid chromium oxide catalysts modified by Mo, W and Mn

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Gaidai, N.A.; Nekrasov, N.V.; Davydov, P.E. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2013-11-01

    Effective chromium oxide catalysts without additions and with addition of Mo, W and Mn were prepared and tested in long-duration experiments for propane dehydrogenation in the presence of CO{sub 2}. The optimal concentrations of metals were found. It was shown that the best combination of acid-base and redox properties necessary for a decrease of aggregation of chromium-oxide particles was observed over the following catalyst: (3.0 wt.%Cr-1.5 wt.% Mn)/SiO{sub 2}. This catalyst worked stably in durable tests (500 h). Mechanism of propane oxidative dehydrogenation was studied using unstationary response method. It was shown that the process mechanism was similar over all studied catalysts but the catalysts were differed by the adsorption capacity of the reaction components: CO{sub 2} was tied more firmly than C{sub 3}H{sub 6} over Cr and Cr-Mn, C{sub 3}H{sub 6} was tied more strongly than CO{sub 2} over Cr-W. The reverse water-gas shift reaction proceeded in more extent over chromium-oxide catalysts without additions. (orig.)

  20. Process of forming catalytic surfaces for wet oxidation reactions

    Science.gov (United States)

    Jagow, R. B. (Inventor)

    1977-01-01

    A wet oxidation process was developed for oxidizing waste materials, comprising dissolved ruthenium salt in a reactant feed stream containing the waste materials. The feed stream is introduced into a reactor, and the reactor contents are then raised to an elevated temperature to effect deposition of a catalytic surface of ruthenium black on the interior walls of the reactor. The feed stream is then maintained in the reactor for a period of time sufficient to effect at least partial oxidation of the waste materials.

  1. Selective catalytic oxidations of alkylaromatic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, R.W. [Celanese GmbH, Oberhausen (Germany); Roehrscheid, F. [Hoechst AG, Frankfurt am Main (Germany). Zentralforschung und Technologie

    1998-12-31

    Focused to the guidelines of `Sustainable Development` `Responsible Care` and `Customer Satisfaction`, modern production processes are critically assessed on their balance between their ecological benefits and their economical parameters as well as their value to the community. Also in the area of fine chemicals, it is obvious that more and more processes are devolved which save feedstock, reduce emissions and minimize the potential for safety hazards: Less additive but more integrated protection of the environment yielding ecologically highly valuable processes. The described production of aromatic carboxylic acids is an ideal example for such a modern process. Nowadays the synthesis of derivatives of benzoic acid utilizes air as Ideal oxidant and acetic acid as environmental unquestionable solvent. The major byproduct of the oxidation reaction is water in some cases, dependend on the substrate also carbon dioxide. (orig.)

  2. Structure and catalytic reactivity of Rh oxides

    DEFF Research Database (Denmark)

    Gustafson, J.; Westerström, R.; Resta, A.;

    2009-01-01

    as well as on Rh nanoparticles. The detailed structure of this film was previously determined using UHV based techniques and density functional theory. In the present paper, we also examine the structure of the bulk Rh2O3 corundum oxide using surface X-ray diffraction. Being armed with this...... structural information, we have explored the CO oxidation reaction over Rh(1 1 1), Rh(1 0 0) and Pt25Rh75(1 0 0) at realistic pressures using in situ surface X-ray diffraction and online mass spectrometry. In all three cases we find that an increase of the CO2 production coincides with the formation of the...

  3. Catalytic mechanisms of direct pyrrole synthesis via dehydrogenative coupling mediated by PNP-Ir or PNN-Ru pincer complexes: Crucial role of proton-transfer shuttles in the PNP-Ir system

    KAUST Repository

    Qu, Shuanglin

    2014-04-02

    Kempe et al. and Milstein et al. have recently advanced the dehydrogenative coupling methodology to synthesize pyrroles from secondary alcohols (e.g., 3) and β-amino alcohols (e.g., 4), using PNP-Ir (1) and PNN-Ru (2) pincer complexes, respectively. We herein present a DFT study to characterize the catalytic mechanism of these reactions. After precatalyst activation to give active 1A/2A, the transformation proceeds via four stages: 1A/2A-catalyzed alcohol (3) dehydrogenation to give ketone (11), base-facilitated C-N coupling of 11 and 4 to form an imine-alcohol intermediate (18), base-promoted cyclization of 18, and catalyst regeneration via H2 release from 1R/2R. For alcohol dehydrogenations, the bifunctional double hydrogen-transfer pathway is more favorable than that via β-hydride elimination. Generally, proton-transfer (H-transfer) shuttles facilitate various H-transfer processes in both systems. Notwithstanding, H-transfer shuttles play a much more crucial role in the PNP-Ir system than in the PNN-Ru system. Without H-transfer shuttles, the key barriers up to 45.9 kcal/mol in PNP-Ir system are too high to be accessible, while the corresponding barriers (<32.0 kcal/mol) in PNN-Ru system are not unreachable. Another significant difference between the two systems is that the addition of alcohol to 1A giving an alkoxo complex is endergonic by 8.1 kcal/mol, whereas the addition to 2A is exergonic by 8.9 kcal/mol. The thermodynamic difference could be the main reason for PNP-Ir system requiring lower catalyst loading than the PNN-Ru system. We discuss how the differences are resulted in terms of electronic and geometric structures of the catalysts and how to use the features in catalyst development. © 2014 American Chemical Society.

  4. Catalytic Hydrolysis of Ammonia Borane by Cobalt Nickel Nanoparticles Supported on Reduced Graphene Oxide for Hydrogen Generation

    Directory of Open Access Journals (Sweden)

    Yuwen Yang

    2014-01-01

    Full Text Available Well dispersed magnetically recyclable bimetallic CoNi nanoparticles (NPs supported on the reduced graphene oxide (RGO were synthesized by one-step in situ coreduction of aqueous solution of cobalt(II chloride, nickel (II chloride, and graphite oxide (GO with ammonia borane (AB as the reducing agent under ambient condition. The CoNi/RGO NPs exhibits excellent catalytic activity with a total turnover frequency (TOF value of 19.54 mol H2 mol catalyst−1 min−1 and a low activation energy value of 39.89 kJ mol−1 at room temperature. Additionally, the RGO supported CoNi NPs exhibit much higher catalytic activity than the monometallic and RGO-free CoNi counterparts. Moreover, the as-prepared catalysts exert satisfying durable stability and magnetically recyclability for the hydrolytic dehydrogenation of AB, which make the practical reusing application of the catalysts more convenient. The usage of the low-cost, easy-getting catalyst to realize the production of hydrogen under mild condition gives more confidence for the application of ammonia borane as a hydrogen storage material. Hence, this general method indicates that AB can be used as both a potential hydrogen storage material and an efficient reducing agent, and can be easily extended to facile preparation of other RGO-based metallic systems.

  5. Effects of Al2O3 phase and Cl component on dehydrogenation of propane

    Science.gov (United States)

    Liu, Jie; Liu, Changcheng; Ma, Aizeng; Rong, Junfeng; Da, Zhijian; Zheng, Aiguo; Qin, Ling

    2016-04-01

    The effects of two Al2O3 phases, γ- and θ-Al2O3, and Cl component on the performances of Pt-Al2O3 catalysts in the dehydrogenation of propane were investigated in this work. The catalysts were systematically characterized by various techniques, such as scanning transmission electron microscopy (STEM), temperature-programmed desorption with ammonia as probe molecules (NH3-TPD) and temperature-programmed oxidation (TPO). The characterizations and catalytic results show that: (i) the pore structures and acid properties of the two Al2O3 phases can change the quantity, location and property of the carbon deposition, (ii) the existence of Cl plays a significant role on the agglomeration of Pt particles and carbon deposition, which further influence the catalytic performances of Pt-Al2O3 catalysts with different support phases for propane dehydrogenation.

  6. Oxidative dehydrogenation of propane with N2O over Fe-ZSM-5 and Fe-SiO2: Influence of the iron species and acid sites

    OpenAIRE

    Ates, Ayten; Hardacre, Christopher; Goguet, Alexandre

    2012-01-01

    A series of iron containing zeolites with varying Si/Al ratios (11.5-140) and low iron content (similar to 0.9 wt.% Fe) have been synthesised by solid-state ion exchange with commercially available zeolites and tested, for the first time, in the oxidative dehydrogenation of propane (ODHP) with N2O. The samples were characterised by XRD, N-2-Adsorption, NH3-TPD and DR-UV-vis spectroscopy. The acidity of the Fe-ZSM-5 can be controlled by high temperature and steam treatments and Si/Al ratio. Th...

  7. Catalytic oxidation of CO on Ir(100)

    Energy Technology Data Exchange (ETDEWEB)

    Erikat, I.A. [Department of Physics, Jerash Private University (Jordan); Hamad, B.A.; Khalifeh, J.M. [Department of Physics, University of Jordan, Amman-11942 (Jordan)

    2011-06-15

    Density functional theory (DFT) calculations are performed to investigate the CO oxidation on Ir(100) surface at different CO coverages, 0.125, 0.25, and 0.5 monolayers (ML). The reaction pathway and transition state (TS) are determined using constrained minimization and nudged elastic band (NEB) methods. We found that the CO molecule is significantly more mobile toward O atoms, which causes a weakening of the O-metal bond. The increase of CO coverage leads to a decrease in the activation energy of the reaction and an increase of O{sub a}-CO distance where O coverage is kept at 0.25 ML. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Zeolite encapsulated Fe-porphyrin for catalytic oxidation with iodobenzene diacetate (PhI(OAc){sub 2})

    Energy Technology Data Exchange (ETDEWEB)

    Karimipour, G.; Rezaei, M.; Ashouri, D. [Yasouj University, Department of Chemistry, 75918-74831 Yasouj (Iran, Islamic Republic of)

    2013-07-01

    meso-Tetrakis(3-pyridyl)porphyrin ato iron(III) chloride encapsulated on NaY Zeolite [Fe(T-3-PyP)-NaY] was synthesized as a heterogeneous ship-in-a-bottle type catalyst and characterized by Fourier transform infrared, atomic absorption, diffused reflectance UV-Vis, X-ray diffraction and scanning electron microscopy analysis. The catalytic activity of Fe(T-3-PyP-NaY was examined for the epoxidation of cyclohexene by PhI(OAc){sub 2} in CH{sub 3}CN/H{sub 2}O (5:1) and compared to that of Fe(T-3-PyP) as a homogeneous catalyst. We found that the heterogeneous catalyst Fe(T-3-PyP-NaY was stable and reusable for several times, and provided a mild condition and exhibited high activity and selectivity in the oxidation of alkenes to epoxides (16-94%). As representative examples for the use of Fe(T-3-PyP-NaY/ PhI(OAc){sub 2} in organic oxidations, oxidation of 4-nitro benzylalcohol to 4-nitrobenzaldehyde (97%), oxidative dehydrogenation of diethyl 4-(2,6-dichlorophenyl)-2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate to the corresponding pyridine (100%), diphenylacetic acid to benzophenone (64%) was achieved. (Author)

  9. Catalytic Partial Oxidation of Biomass/Oil Dispersion

    Czech Academy of Sciences Publication Activity Database

    Hanika, Jiří; Lederer, J.; Nečesaný, F.; Poslední, W.; Tukač, V.; Veselý, Václav

    Praha: Orgit, 2013 - (Kalenda, P.; Lubojacký, J.), 9-12 ISBN 978-80-86238-55-5. [International Conference on Chemical Technology (ICCT 2013) /1./. Mikulov (CZ), 08.04.2013-10.04.2013] R&D Projects: GA TA ČR TE01020080; GA MPO 2A-2TP1/024 Institutional support: RVO:67985858 Keywords : hydrocarbon oil * biomass * catalytic partial oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  10. Catalytic Partial Oxidation of Biomass/Oil Mixture

    OpenAIRE

    Veselý, V; Hanika, J. (Jiří); Tukač, V.; LEDERER, J.; Kovač, D.

    2013-01-01

    Investigation was focussed to application of waste POX (partial oxidation), e.g., meal rape in form of suspension in high boiling hydrocarbons from crude oil distillation. There is an opportunity for utilization of biomass waste resulted from fuels bio-components production. A decrease of oxygen and water steam demand in feed for POX process was observed in this variant. Catalytic effect of iron nanoparticles or nickel nitrate as catalysts in improvement of the pilot plant biomass/oil partial...

  11. Deep desulfurization of diesel fuels by catalytic oxidation

    Institute of Scientific and Technical Information of China (English)

    YU Guoxian; CHEN Hui; LU Shanxiang; ZHU Zhongnan

    2007-01-01

    Reaction feed was prepared by dissolving dibenzothiophene (DBT),which was selected as a model organosulfur compound in diesel fuels,in n-octane.The oxidant was a 30 wt-% aqueous solution of hydrogen peroxide.Catalytic performance of the activated carbons with saturation adsorption of DBT was investigated in the presence of formic acid.In addition,the effects of activated carbon dosage,formic acid concentration,initial concentration of hydrogen peroxide,initial concentration of DBT and reaction temperature on the oxidation of DBT were investigated.Experimental results indicated that performic acid and the hydroxyl radicals produced are coupled to oxidize DBT with a conversion ratio of 100%.Catalytic performance of the combination of activated carbon and formic acid is higher than that ofouly formic acid.The concentration of formic acid,activated carbon dosage,initial concentration of hydrogen peroxide and reaction temperature affect the oxidative removal of DBT.The higher the initial concentration of DBT in the n-octane solution,the more difficult the deep desulfurization by oxidation is.

  12. Catalytic oxidation of volatile organic compounds (VOCs) - A review

    Science.gov (United States)

    Kamal, Muhammad Shahzad; Razzak, Shaikh A.; Hossain, Mohammad M.

    2016-09-01

    Emission of volatile organic compounds (VOCs) is one of the major contributors to air pollution. The main sources of VOCs are petroleum refineries, fuel combustions, chemical industries, decomposition in the biosphere and biomass, pharmaceutical plants, automobile industries, textile manufacturers, solvents processes, cleaning products, printing presses, insulating materials, office supplies, printers etc. The most common VOCs are halogenated compounds, aldehydes, alcohols, ketones, aromatic compounds, and ethers. High concentrations of these VOCs can cause irritations, nausea, dizziness, and headaches. Some VOCs are also carcinogenic for both humans and animals. Therefore, it is crucial to minimize the emission of VOCs. Among the available technologies, the catalytic oxidation of VOCs is the most popular because of its versatility of handling a range of organic emissions under mild operating conditions. Due to that fact, there are numerous research initiatives focused on developing advanced technologies for the catalytic destruction of VOCs. This review discusses recent developments in catalytic systems for the destruction of VOCs. Review also describes various VOCs and their sources of emission, mechanisms of catalytic destruction, the causes of catalyst deactivation, and catalyst regeneration methods.

  13. Structure and properties of oxidative dehydrogenation catalysts based on MoO3/Al2O3

    International Nuclear Information System (INIS)

    The effects of MoOx structure on propane oxidative dehydrogenation (ODH) rates and selectivity were examined on Al2O3-supported molybdenum oxide catalysts with a wide range of Mo surface density (0.4-12 Mo/nm2). X-ray diffraction and Raman, UV-visible, and X-ray absorption spectroscopies showed that the structure of dispersed molybdena depends strongly on the Mo surface density. Two-dimensional MoOx oligomers formed preferentially for Mo surface densities below 4 Mo/nm2. At higher surface densities, these MoOx oligomers coexist on Al2O3 surfaces with three-dimensional MoO3. UV-visible edge energies decrease with increasing Mo surface density, consistent with the growth of MoOx structures. The evolution of near-edge spectral features in the X-ray absorption spectra and the gradual appearance of a Mo-Mo scattering peak in the radial structure function confirmed the growth of MoOx domains with increasing surface density. ODH rates per Mo atom increased with increasing Mo surface density a nd reached a maximum value for samples with (a) 4.5 Mo/nm2; this behavior reflects an increase in the reactivity of surface Mo species, because all MoOx species are exposed at domain surfaces in this surface density range. As also shown for VOx-based catalysts, turnover rates are higher on two-dimensional domains than on isolated monomers and they increase as the MoOx domain size increases. The rates of reduction of MoOx species in H2 or C3H8 were probed using kinetic and X-ray absorption methods; these reduction rates increased in parallel with ODH rates as the MoOx surface density increased, apparently as a result of the ability of larger domains to delocalize the higher electron density that accompanies the reduction process. As the surface density increased above 4.5 Mo/nm2, ODH rates (per Mo atom) decrease, as a result of the loss of accessibility caused by the formation of MoO3 crystallites. For these latter samples, the ODH rate per BET surface area approached a constant value

  14. Catalytic oxidative desulfurization of liquid hydrocarbon fuels using air

    Science.gov (United States)

    Sundararaman, Ramanathan

    Conventional approaches to oxidative desulfurization of liquid hydrocarbons involve use of high-purity, expensive water soluble peroxide for oxidation of sulfur compounds followed by post-treatment for removal of oxidized sulfones by extraction. Both are associated with higher cost due to handling, storage of oxidants and yield loss with extraction and water separation, making the whole process more expensive. This thesis explores an oxidative desulfurization process using air as an oxidant followed by catalytic decomposition of sulfones thereby eliminating the aforementioned issues. Oxidation of sulfur compounds was realized by a two step process in which peroxides were first generated in-situ by catalytic air oxidation, followed by catalytic oxidation of S compounds using the peroxides generated in-situ completing the two step approach. By this technique it was feasible to oxidize over 90% of sulfur compounds present in real jet (520 ppmw S) and diesel (41 ppmw S) fuels. Screening of bulk and supported CuO based catalysts for peroxide generation using model aromatic compound representing diesel fuel showed that bulk CuO catalyst was more effective in producing peroxides with high yield and selectivity. Testing of three real diesel fuels obtained from different sources for air oxidation over bulk CuO catalyst showed different level of effectiveness for generating peroxides in-situ which was consistent with air oxidation of representative model aromatic compounds. Peroxides generated in-situ was then used as an oxidant to oxidize sulfur compounds present in the fuel over MoO3/SiO2 catalyst. 81% selectivity of peroxides for oxidation of sulfur compounds was observed on MoO3/SiO2 catalyst at 40 °C and under similar conditions MoO3/Al2O3 gave only 41% selectivity. This difference in selectivity might be related to the difference in the nature of active sites of MoO3 on SiO2 and Al2O 3 supports as suggested by H2-TPR and XRD analyses. Testing of supported and bulk Mg

  15. Catalytic oxidation of carbon monoxide over supported palladium nanoparticles

    Science.gov (United States)

    Soni, Keshav Chand; Krishna, R.; Chandra Shekar, S.; Singh, Beer

    2016-01-01

    Catalytic oxidation of CO with ozone had been studied over Al2O3 and SiO2 supported Pd nanoparticles which was synthesized by two different methods. The polyol method mainly resulted in highly dispersed Pd particles on the support, while the impregnation method resulted in agglomeration Pd particles on the support. Supported Pd nanoparticles synthesized from PdCl2 in the presence of poly ( N-vinylpyrrolidone) (PVP) by chemical reduction. The catalysts were characterized by X-ray diffraction, N2 BET surface area, pore size distributions, CO chemisorption, TEM and H2-temperature programmed reduction. The physico-chemical properties were well correlated with activity data. Characterizations of XRD and TEM show that the surface Pd nanoparticles are highly dispersed over Al2O3 and SiO2. The catalytic activity was dependent upon ozone/CO ratio, contact times, and the reaction temperature. The extent of carbon monoxide oxidation was proportional to the catalytically ozone decomposition. The PVP synthesized Pd/A2O3 catalyst had been found to be highly active for complete CO removal at room temperature. The higher activity of the nanocatalyst was attributed to small particle size and higher dispersion of Pd over support.

  16. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: kinetics and biodegradability enhancement.

    Science.gov (United States)

    Suárez-Ojeda, María Eugenia; Kim, Jungkwon; Carrera, Julián; Metcalfe, Ian S; Font, Josep

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15 bar of oxygen partial pressure (P(O2)) and at 180, 200 and 220 degrees C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P(O2) were 140-160 degrees C and 2-9 bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160 degrees C and 2 bar of P(O2), which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD(RB)) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture. PMID:17363148

  17. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Kinetics and biodegradability enhancement

    International Nuclear Information System (INIS)

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure (PO2) and at 180, 200 and 220deg. C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and PO2 were 140-160deg. C and 2-9bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160deg. C and 2 bar of PO2, which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (CODRB) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture

  18. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Kinetics and biodegradability enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Ojeda, Maria Eugenia [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia (Spain); Departament d' Enginyeria Quimica, Edifici Q-ETSE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia (Spain); Kim, Jungkwon [Chemical Engineering and Analytical Sciences Department, University of Manchester, Manchester (United Kingdom); Carrera, Julian [Departament d' Enginyeria Quimica, Edifici Q-ETSE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia (Spain); Metcalfe, Ian S. [Chemical Engineering and Advanced Materials Department, University of Newcastle upon Tyne, Newcastle upon Tyne (United Kingdom); Font, Josep [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia (Spain)]. E-mail: jose.font@urv.cat

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure (P{sub O{sub 2}}) and at 180, 200 and 220deg. C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P{sub O{sub 2}} were 140-160deg. C and 2-9bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160deg. C and 2 bar of P{sub O{sub 2}}, which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD{sub RB}) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture.

  19. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption – Catalytic wet air oxidation on activated carbons

    International Nuclear Information System (INIS)

    Highlights: ► Three activated carbons (AC) compared as adsorbents and oxidation catalysts. ► Similar evolution for catalytic and adsorptive properties of AC over reuses. ► Acidic and mesoporous AC to be preferred, despite lower initial efficiency. ► Oxidative degradation of paracetamol improves biodegradability. ► Convenient hybrid adsorption–regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  20. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Quesada-Penate, I. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Julcour-Lebigue, C., E-mail: carine.julcour@ensiacet.fr [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Jauregui-Haza, U.J. [Instituto Superior de Tecnologias y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Habana (Cuba); Wilhelm, A.M.; Delmas, H. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Three activated carbons (AC) compared as adsorbents and oxidation catalysts. Black-Right-Pointing-Pointer Similar evolution for catalytic and adsorptive properties of AC over reuses. Black-Right-Pointing-Pointer Acidic and mesoporous AC to be preferred, despite lower initial efficiency. Black-Right-Pointing-Pointer Oxidative degradation of paracetamol improves biodegradability. Black-Right-Pointing-Pointer Convenient hybrid adsorption-regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  1. A study of the effect of cesium loading on the phase transformation of iron in iron phosphate over the oxidative dehydrogenation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Faiza B.; Dasireddy, Venkata D. B. C., E-mail: Dasireddy@gmail.com; Bharuth-Ram, K. [University of KwaZulu-Natal, School of Chemistry and Physics (South Africa); Masenda, H. [University of the Witwatersrand, School of Physics (South Africa); Friedrich, H. B. [University of KwaZulu-Natal, School of Chemistry and Physics (South Africa)

    2015-04-15

    A phase specific iron orthophosphate catalyst, FePO{sub 4}, was synthesized and promoted with cesium. This catalyst was subjected to oxidative dehydrogenation reactions to form an alkyl methacrylate. The phases of the catalyst, before and after the reactions, were studied as a function of different cesium loading. Mössbauer spectra of the catalysts show the change of the catalyst precursor FePO{sub 4}, to i) the tridymite-like phase, ii) the reduced form, iron(II) pyrophosphate and Fe{sub 2}P{sub 2}O{sub 7,} and iii) the α-phase of iron phosphate which is governed by the temperatures of oxidation. X-ray diffraction and Mössbauer measurements on the spent catalyst show a transformation of the catalyst to a mixture of phases.

  2. A study of the effect of cesium loading on the phase transformation of iron in iron phosphate over the oxidative dehydrogenation reactions

    International Nuclear Information System (INIS)

    A phase specific iron orthophosphate catalyst, FePO4, was synthesized and promoted with cesium. This catalyst was subjected to oxidative dehydrogenation reactions to form an alkyl methacrylate. The phases of the catalyst, before and after the reactions, were studied as a function of different cesium loading. Mössbauer spectra of the catalysts show the change of the catalyst precursor FePO4, to i) the tridymite-like phase, ii) the reduced form, iron(II) pyrophosphate and Fe2P2O7, and iii) the α-phase of iron phosphate which is governed by the temperatures of oxidation. X-ray diffraction and Mössbauer measurements on the spent catalyst show a transformation of the catalyst to a mixture of phases

  3. Catalytic aerobic oxidation of bio-renewable chemicals

    DEFF Research Database (Denmark)

    Gorbanev, Yury

    This thesis covers the investigation of new catalytic systems for the aerobic oxidation of chemicals derived from bio-renewable sources. The effects of different factors and conditions on the reactions were examined. The employed catalysts were characterized by physisorption measurements, SEM, TEM......, EDS, XRF and other methods. Supported gold and ruthenium hydroxide catalyst systems were explored for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDA), a potential polymer building block for the plastic industry, or its dimethyl ester (FDMC). High product...... selectivities and yields were obtained under optimized conditions. Heterogeneous catalysts consisting of Au nanoparticles on different supports were shown to efficiently oxidize HMF to FDA or FDMC in water or methanol, respectively. Additionally, the reaction conditions were shown to be adjustable...

  4. Structure and Catalytic Behavior of CuO-ZrO-CeO2 Mixed Oxides

    Institute of Scientific and Technical Information of China (English)

    王恩过; 陈诵英

    2002-01-01

    The effect of doping CuO on the structure and properties of zirconia-ceria mixed oxide was studied. The results show that addition of CuO decreases the reduction temperature of ceria, and stabilizes the cubic structure of mixed oxides, and enhances catalytic activity of CuO-ZrO-CeO2 mixed oxides for CO oxidation. Increasing ceria content in the mixed oxides can enhance the catalytic activity, but some impurities such as sulfate make catalytic activity falling. There is little effect of calcination temperature on catalytic activities, implying that these catalysts are effective with good thermal stability.

  5. Session 6: The catalytic oxidation of selected chlorinated hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Oszczudlowski, J. [Institute of Chemistry, Swietokrzyska Academy, Kielce (Poland)

    2004-07-01

    The catalytic oxidation of selected chlorinated hydrocarbons was investigated in the presence of natural zeolites modified with 3M HCl and chromium and lanthanum from aqueous solutions. Natural zeolites of the structure of clinoptilolite or mordenite possess unique physical and chemical properties such as high sorptive capacity and ion-exchange selectivity, relatively high heat and mechanical resistance. The activation of samples of natural zeolites was carried out in a 3M aqueous solution of HCl using a Soxhlet apparatus, whereas the ion exchange from aqueous solutions of chromium (III) and lanthanum (III) nitrates. Samples of activated zeolites were calcinated at 500 C with a programmable temperature increase within 4 hours The amounts of Cr and La on zeolite were 3,0 % wt and 4,5 % wt, respectively. Catalytic tests were conducted in a micro-reactor coupled with a gas chromatograph. The conditions of reaction were as follows: temperature range: 473-723 K, substrate composition: chlorinated hydrocarbon (1000-10000 ppm), steam (0-10000 ppm) and air. Under standard conditions volatile chlorinated hydrocarbons were introduced into a gas flux as vapours, whereas low-volatile ones in a mixture with n-hexane or cyclohexane. The quantity of the deposits on the surface of a catalyst was analysed by the thermogravimetric and GC-MS methods. The composition of oxidation products of chlorinated hydrocarbons was chromatographically analysed indirectly with the techniques SPME-GC-ECD and SPME-GCFID. The total quantity of the products was stored in gas containers-Tedlars and the quantitative and qualitative composition was analysed by the method SPME-HS-GC-ECD (solid phase micro-extraction-headspace-gas chromatography-electron capture detector). The total oxidation of CCl{sub 4} and C{sub 2}Cl{sub 6} in the presence of the Cr/zeolite catalyst occurs at 400 C. The conversion of the catalytic oxidation of chloro-olefins in the presence of the La/zeolite catalyst increases within

  6. Coupling dehydrogenation of isobutane in the presence of carbon dioxide over chromium oxide supported on active carbon

    Institute of Scientific and Technical Information of China (English)

    Jian Fei Ding; Zhang Feng Qin; Xue Kuan Li; Guo Fu Wang; Jian Guo Wang

    2008-01-01

    The dehydrogenation of isobutane (IB) to produce isobutene coupled with reverse water gas shift in the presence of carbon dioxide was investigated over the catalyst Cr2O3 supported on active carbon (Cr2O3/AC). The results illustrated that isobutane c onversion and isobutene yield can be enhanced through the reaction coupling in the presence of carbon dioxide. Moreover, carbon dioxide can partially eliminate carbonaceous deposition on the catalyst and keep the active phase (Cr2O3), which are then helpful to alleviate the catalyst deactivation.

  7. The selective catalytic reduction (SCR) of NO with NH3 at vanadium oxide catalysts: Adsorption, diffusion, reaction

    International Nuclear Information System (INIS)

    The selective catalytic reduction (SCR) of NOx with NH3 over vanadium based metal-oxide (VOx) catalysts has been proven to be one of the most effective NOx reduction processes. Even though it is widely used in commercial applications details of the reaction mechanism are still under debate. Experiments show that adsorption, diffusion, and reactions with NO and (de)hydrogenation processes at the VOx surface contribute elementary steps. These processes are examined in theoretical studies employing density-functional theory together with gradient corrected functionals. The VOx substrate is modeled by clusters cut out from the ideal V2O5(010) surface where peripheral oxygen bonds are saturated by hydrogen. Apart from the perfect oxide surface also differently reduced surfaces are considered by introducing oxygen vacancies. NH3 is found to interact only weakly with the perfect V2O5(010) surface. In the presence of OH groups (Broensted acid sites) NH3 can form a surface NH4+ species. NH3 can also interact with the surface near oxygen vacancies, adsorbing at vanadium centers of lower coordination (Lewis acid sites). In contrast, NO interacts much more weakly with the surface. Further, simultaneous NO, NH3 adsorption and SCR reaction scenarios at Broensted and Lewis acid sites are examined. They result in different reaction paths and intermediates as will be discussed in detail.

  8. Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling

    KAUST Repository

    Takanabe, Kazuhiro

    2012-01-01

    Natural gas conversion remains one of the essential technologies for current energy needs. This review focuses on the mechanistic aspects of the development of efficient and durable catalysts for two reactions, carbon dioxide reforming and the oxidative coupling of methane. These two reactions have tremendous technological significance for practical application in industry. An understanding of the fundamental aspects and reaction mechanisms of the catalytic reactions reviewed in this study would support the design of industrial catalysts. CO 2 reforming of methane utilizes CO 2, which is often stored in large quantities, to convert as a reactant. Strategies to eliminate carbon deposition, which is the major problem associated with this reaction, are discussed. The oxidative coupling of methane directly produces ethylene in one reactor through a slightly exothermic reaction, potentially minimizing the capital cost of the natural gas conversion process. The focus of discussion in this review will be on the attainable yield of C 2 products by rigorous kinetic analyses.

  9. Catalytic wet air oxidation for the treatment of emulsifying wastewater

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jian-fu; CHEN Ling; LU Yi-cheng; TANG Wen-wei

    2005-01-01

    The wet air oxidation (WAO) and catalytic WAO (CWAO) of the high strength emulsifying wastewater containing nonionic surfactants have been investigated in terms of COD and TOC removal. The WAO and homogeneous CWAO processes were carried out at the temperature from 433 K to 513 K, with initial oxygen pressure 1.2 MPa. It was found that homogeneous catalyst copper(Cu ( NO3 )2 )had an fairly good catalytic activity for the WAO process, and the oxidation was catalyzed when the temperature was higher than 473 K.Moreover, several heterogeneous catalysts were proved to be effective for the WAO process. At the temperature 473 K, after 2 h reaction,WAO process could achieve about 75% COD removal and 66% TOC removal, while catalysts Cu/Al2O3 and Mn-Ce/Al2O3 elevated the COD removal up to 86%-89% and that of TOC up to 82%. However, complete elimination of COD and TOC was proved to be difficult even the best non-noble catalyst was used. Therefore, the effluent from WAO or CWAO process need to be further disposed. The bioassay proved that the effluent from WAO process was amenable to the biochemical method.

  10. Copper on activated carbon for catalytic wet air oxidation

    Directory of Open Access Journals (Sweden)

    Nora Dolores Martínez

    2009-03-01

    Full Text Available Textile industry is an important source of water contamination. Some of the organic contaminants cannot be eliminated by nature in a reasonable period. Heterogeneous catalytic wet air oxidation is one of the most effective methods to purify wastewater with organic contaminants. In this work, catalysts based on copper supported on activated carbon were synthesized. The activated carbons were obtained from industrial wastes (apricot core and grape stalk of San Juan, Argentina. These were impregnated with a copper salt and thermically treated in an inert atmosphere. Analysis of specific surface, pore volume, p zc, acidity, basicity and XRD patterns were made in order to characterize the catalysts. The catalytic activity was tested in the oxidation of methylene blue (MB and polyvinyl alcohol (PVA in aqueous phase with pure oxygen. Reaction tests were carried out in a Parr batch reactor at different temperatures, with a 0.2 MPa partial pressure of oxygen. The amount of unconverted organics was measured by spectrophotometry. Higher temperatures were necessary for the degradation of PVA compared to those for methylene blue.

  11. Catalytic oxidation of tritium in air at ambient temperature

    International Nuclear Information System (INIS)

    Tritium/air oxidation kinetic data are derived from ambient-temperature measurements carried out with three precious-metal catalysts. Each catalyst consists of a high-surface-area substrate in pelletized form, onto which precious metal has been dispersed. The metal/substrate combinations investigated are platinum/alumina, palladium/kaolin, and palladium/zeolite. Electron-microprobe scans reveal that the dispersed metal is deposited in each case near the outer surface of the pellet, with metal concentration decreasing exponentially from the pellet surface. Kinetic oxidation measurements are made in a unique apparatus consisting of a large Lucite enclosure with an air atmosphere processed by a recirculating cleanup system. Dual-ionization chambers with an intermediate adsorption bed permit measurement of tritium gas and tritiated water vapor. Rate coefficients are determined from concentration decay following a spike injection of tritium into the enclosure. The catalytic reaction is first-order in tritium concentration in the range 10 to 105 μCi/m3. Addition of hydrogen carrier gas is unnecessary. Each of the dispersed-metal catalysts is extremely active in promoting tritium oxidation in comparison with self-catalyzed atmospheric conversion; equivalent first-order rate constants are higher by roughly 9 orders of magnitude. The platinum-based catalyst is more effective than the palladium catalysts on a surface-area basis by about a factor of 3. Catalytic activity for all three catalysts declines with time of exposure to air after activation, following a power-law decay with an exponent of -1/2. A model for optimization of the catalyst reactivation cycle is proposed, revealing that the optimum catalyst volume scales with flow rate to the 2/3 power. Ambient-temperature tritium oxidation is cost-effective for small- to intermediate-scale cleanup systems. A heated catalyst is desirable for large-scale systems

  12. Removal of formaldehyde over MnxCe1-xO2 catalysts: Thermal catalytic oxidation versus ozone catalytic oxidation

    Institute of Scientific and Technical Information of China (English)

    Jia Wei Li; Kuan Lun Pan; Sheng Jen Yu; Shaw Yi Yan; Moo Been Chang

    2014-01-01

    MnxCe1-xO2 (x:0.3-0.9) prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde (HCHO).At x =0.3 and 0.5,most of the manganese was incorporated in the fluorite structure of CeO2 to form a solid solution.The catalytic activity was best at x =0.5,at which the temperature of 100% removal rate is the lowest (270℃).The temperature for 100% removal of HCHO oxidation is reduced by approximately 40℃ by loading 5 wt.% CuOx into Mn0.5Ce0.5O2.With ozone catalytic oxidation,HCHO (61 ppm) in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV (gas hourly space velocity) of 10,000 hr-1 at 25℃.The effect of the molar ratio of O3 to HCHO was also investigated.As O3/HCHO ratio was increased from 3 to 8,the removal efficiency of HCHO was increased from 83.3% to 100%.With O3/HCHO ratio of 8,the mineralization efficiency of HCHO to CO2 was 86.1%.At 25℃,the p-type oxide semiconductor (Mn0.5Ce0.5O2) exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as TiO2,which had a low ozone decomposition efficiency (9.81%).At a GHSV of 10,000 hr-1,[O3]/[HCHO] =3 and temperature of 25℃,a high HCHO removal efficiency (≥81.2%) was maintained throughout the durability test of 80 hr,indicating the long-term stability of the catalyst for HCHO removal.

  13. The catalytic activity of several tungsten oxides for the oxidation of propene

    International Nuclear Information System (INIS)

    A study has been made of the catalytic oxidation of propene over the oxides WO3, WOsub(2,95), WOsub(2,90), WOsub(2,72) and Wo2, which were selected because they possess specific features of chemical and structural interest rather than for their catalytic ability. It was found that the oxides WOsub(2,95), WOsub(2,90) and WOsub(2,72) all selectively produce acrolein in small amounts. The oxides WO3 and WO2 were non-selective and rather inactive. The results are discussed in terms of a mechanism involving both variable valence in the crystal and the specific structural geometry of these compounds. (orig.)

  14. Catalytic oxidation of dithiols by a semisynthetic enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, K.D.; Radziejewski, C.; Kaiser, E.T.

    1986-06-11

    The semisynthetic enzyme flavopapain (1C), obtained from the alkylation of Cys-25 of papain with 8..cap alpha..-(bromo-acetyl)-10-methylsioalloxazine (1B), was found to be an effective catalysts for the oxidation of dithiols to disulfides. The k/sub 2//K/sub s/ values for the oxidation of d,l-dihydrolipoamide and d,l-dihydrolipoic acid determined from anaerobic single-reaction stopped-flow kinetics were 4400 and 3400 M/sup -1/s/sup -1/, respectively. These values were, respectively, 126 and 200 times larger than the second-order rate constants for oxidation of d,l-dihydrolipoamide and d,l-dihydrolipoic acid by the model flavin 8-acetyl-10-methylisoalloxazine (1A). Under aerobic turnover conditions using the synthetic dye MTT as an electron acceptor, the k/sub cat/ and K/sub m/ values for the oxidation of d,l-dihydrolipoamide by 1C were in approximate agreement with the k/sub 2/ and K/sub s/ values, indicating that the rate-limiting step of the catalytic cycle is substrate oxidation rather than oxidation of dihydroflavopapain. When compared with flavopapains 2C and 3C (obtained as above but by modification with 7..cap alpha..- and 6..cap alpha..-(bromoacetyl)-10-methylisoalloxazine (2B and 3B, respectively)), flavopapain 1C is the most efficient catalyst. The circular dichroic spectra of flavopapains 1C, 2C, and 3C were recorded, and the dissociation constants of the sulfite addition complexes of 1C and 2C were determined.

  15. Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-09-29

    A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase is dispersed.

  16. Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

    Science.gov (United States)

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-03-17

    A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase id dispersed.

  17. Catalytic properties and biomedical applications of cerium oxide nanoparticles

    KAUST Repository

    Walkey, Carl D.

    2014-11-10

    Cerium oxide nanoparticles (nanoceria) have shown promise as catalytic antioxidants in the test tube, cell culture models and animal models of disease. However given the reactivity that is well established at the surface of these nanoparticles, the biological utilization of nanoceria as a therapeutic still poses many challenges. Moreover the form that these particles take in a biological environment, such as the changes that can occur due to a protein corona, are not well established. This review aims to summarize the existing literature on biological use of nanoceria, and to raise questions about what further study is needed to apply this interesting catalytic material to biomedical applications. These questions include: 1) How does preparation, exposure dose, route and experimental model influence the reported effects of nanoceria in animal studies? 2) What are the considerations to develop nanoceria as a therapeutic agent in regards to these parameters? 3) What biological targets of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are relevant to this targeting, and how do these properties also influence the safety of these nanomaterials?

  18. Development of an oxidative dehydrogenation-based fluorescent probe for Cu{sup 2+} and its biological imaging in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Fan Jiangli, E-mail: fanjl@dlut.edu.cn [State Key Laboratory of Fine Chemicals, Dalian University of Technology, No. 2 Linggong Road, High-tech District, Dalian 116024 (China); Liu Xiaojian; Hu Mingming; Zhu Hao; Song Fengling [State Key Laboratory of Fine Chemicals, Dalian University of Technology, No. 2 Linggong Road, High-tech District, Dalian 116024 (China); Peng Xiaojun, E-mail: pengxj@dlut.edu.cn [State Key Laboratory of Fine Chemicals, Dalian University of Technology, No. 2 Linggong Road, High-tech District, Dalian 116024 (China)

    2012-07-20

    Highlights: Black-Right-Pointing-Pointer The fluorescent probe contains an N, O and S tridentate ligand. Black-Right-Pointing-Pointer The probe is simple but highly sensitive and selective toward Cu{sup 2+}. Black-Right-Pointing-Pointer The mechanism is based on the Cu{sup 2+}-promoted dehydrogenation of amine in different organic and aqueous solutions. Black-Right-Pointing-Pointer It was successfully applied to visualize Cu{sup 2+} in living cells. - Abstract: Based on a boron dipyrromethene (BODIPY) derivative containing an N, O and S tridentate ligand, a Cu{sup 2+} fluorescent probe BTCu was developed. The detection mechanism was verified as Cu{sup 2+}-promoted oxidative dehydrogenation of an amine moiety, leading to a formation of a fluorescent Cu{sup +}-Schiff base complex. Free BTCu exhibited a maximum absorption wavelength at 496 nm, and a very weak maximum emission at 511 nm. Upon addition of various metals ions, it showed large fluorescence enhancement toward Cu{sup 2+} (417-fold in MeCN and 103-fold in MeCN/HEPES solution, respectively) with high selectivity. The detection limits are as low as 1.74 Multiplication-Sign 10{sup -8} M and 4.96 Multiplication-Sign 10{sup -8} M in the two different solutions, respectively. And BTCu could work in a wide pH range with an extraordinary low pK{sub a} of 1.21 {+-} 0.06. Using fluorescence microscopy, the probe was shown to be capable of penetrating into living cells and imaging intracellular Cu{sup 2+} changes.

  19. Methylene Blue Inhibits Caspases by Oxidation of the Catalytic Cysteine.

    Science.gov (United States)

    Pakavathkumar, Prateep; Sharma, Gyanesh; Kaushal, Vikas; Foveau, Bénédicte; LeBlanc, Andrea C

    2015-01-01

    Methylene blue, currently in phase 3 clinical trials against Alzheimer Disease, disaggregates the Tau protein of neurofibrillary tangles by oxidizing specific cysteine residues. Here, we investigated if methylene blue can inhibit caspases via the oxidation of their active site cysteine. Methylene blue, and derivatives, azure A and azure B competitively inhibited recombinant Caspase-6 (Casp6), and inhibited Casp6 activity in transfected human colon carcinoma cells and in serum-deprived primary human neuron cultures. Methylene blue also inhibited recombinant Casp1 and Casp3. Furthermore, methylene blue inhibited Casp3 activity in an acute mouse model of liver toxicity. Mass spectrometry confirmed methylene blue and azure B oxidation of the catalytic Cys163 cysteine of Casp6. Together, these results show a novel inhibitory mechanism of caspases via sulfenation of the active site cysteine. These results indicate that methylene blue or its derivatives could (1) have an additional effect against Alzheimer Disease by inhibiting brain caspase activity, (2) be used as a drug to prevent caspase activation in other conditions, and (3) predispose chronically treated individuals to cancer via the inhibition of caspases. PMID:26400108

  20. Mercury Oxidation via Catalytic Barrier Filters Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Wayne Seames; Michael Mann; Darrin Muggli; Jason Hrdlicka; Carol Horabik

    2007-09-30

    In 2004, the Department of Energy National Energy Technology Laboratory awarded the University of North Dakota a Phase II University Coal Research grant to explore the feasibility of using barrier filters coated with a catalyst to oxidize elemental mercury in coal combustion flue gas streams. Oxidized mercury is substantially easier to remove than elemental mercury. If successful, this technique has the potential to substantially reduce mercury control costs for those installations that already utilize baghouse barrier filters for particulate removal. Completed in 2004, Phase I of this project successfully met its objectives of screening and assessing the possible feasibility of using catalyst coated barrier filters for the oxidation of vapor phase elemental mercury in coal combustion generated flue gas streams. Completed in September 2007, Phase II of this project successfully met its three objectives. First, an effective coating method for a catalytic barrier filter was found. Second, the effects of a simulated flue gas on the catalysts in a bench-scale reactor were determined. Finally, the performance of the best catalyst was assessed using real flue gas generated by a 19 kW research combustor firing each of three separate coal types.

  1. Dehydrogenation of ammonia borane through the third equivalent of hydrogen.

    Science.gov (United States)

    Zhang, Xingyue; Kam, Lisa; Williams, Travis J

    2016-05-01

    Ammonia borane (AB) has high hydrogen density (19.6 wt%), and can, in principle, release up to 3 equivalents of H2 under mild catalytic conditions. A limited number of catalysts are capable of non-hydrolytic dehydrogenation of AB beyond 2 equivalents of H2 under mild conditions, but none of these is shown directly to derivatise borazine, the product formed after 2 equivalents of H2 are released. We present here a high productivity ruthenium-based catalyst for non-hydrolytic AB dehydrogenation that is capable of borazine dehydrogenation, and thus exhibits among the highest H2 productivity reported to date for anhydrous AB dehydrogenation. At 1 mol% loading, (phen)Ru(OAc)2(CO)2 () effects AB dehydrogenation through 2.7 equivalents of H2 at 70 °C, is robust through multiple charges of AB, and is water and air stable. We further demonstrate that catalyst has the ability both to dehydrogenate borazine in isolation and dehydrogenate AB itself. This is important, both because borazine derivatisation is productivity-limiting in AB dehydrogenation and because borazine is a fuel cell poison that is commonly released in H2 production from this medium. PMID:27052687

  2. Homogeneous catalytic wet air oxidation for the treatment oftextile wastewaters

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An extensive series of experiments was carried out in order to identify suitable catalysts to boost the reaction rate of wet air oxidation of real textile wastewaters at relatively mild temperature and pressure. Experimental results indicated that all catalysts tested in this investigation had shown an impressive increase in the initial COD and TOC removal rate as well as the COD and TOC removal levels in two hours reaction. Among all the catalysts tested, copper salts were more effective than the rest. Anions of the salt soluffonsalso played a role in the catalytic process with nitrate ions having better effect than sulfate ions. Hence copper nitrates were more effective than copper sulfates. It was also found that a mixture of salts with different metals performed better than either of the component single salt alone.

  3. CuO impregnated activated carbon for catalytic wet peroxide oxidation of phenol

    International Nuclear Information System (INIS)

    This paper presents an original approach to the removal of phenol in synthetic wastewater by catalytic wet peroxide oxidation with copper binding activated carbon (CuAC) catalysts. The characteristics and oxidation performance of CuAC in the wet hydrogen peroxide catalytic oxidation of phenol were studied in a batch reactor at 80 deg. C. Complete conversion of the oxidant, hydrogen peroxide, was observed with CuAC catalyst in 20 min oxidation, and a highly efficient phenol removal and chemical oxygen demand (COD) abatement were achieved in the first 30 min. The good oxidation performance of CuAC catalyst was contributed to the activity enhancement of copper oxide, which was binding in the carbon matrix. It can be concluded that the efficiency of oxidation dominated by the residual H2O2 in this study. An over 90% COD removal was achieved by using the multiple-step addition in this catalytic oxidation.

  4. Low temperature catalytic decomposition and oxidation of MTBE

    International Nuclear Information System (INIS)

    Catalytic combustion of methyl-tert-butyl-ether (MTBE) was studied in the gas-phase from an aqueous solution spiked with MTBE (1.1mM), to simulate actual remediation conditions. The solution of MTBE was sparged with an oxygen/helium gas, at a ratio of 1-4. The sparged gas stream of MTBE and water vapor was passed over catalysts utilizing Pt/Rh or Pd in conjunction with a mixed metal oxide based upon La1-xSrxMnO3. The results were compared to a commercial catalyst which contained a higher loading of Pt. The experiments with the catalysts were conducted over a temperature range of 80-500C. Combustion to CO2 and water was observed in all cases, but by-product formation of isobutene and methanol was seen at lower temperatures for all of the catalysts tested, with the exception of the commercial catalyst. The catalyst with the lowest loading of Pt/Rh achieved the lowest temperature for complete oxidation of MTBE and its by-products

  5. Structural changes and dynamic behaviour of vanadium oxide-based catalysts for gas-phase selective oxidations

    OpenAIRE

    Luciani, Silvia

    2009-01-01

    Selective oxidation is one of the simplest functionalization methods and essentially all monomers used in manufacturing artificial fibers and plastics are obtained by catalytic oxidation processes. Formally, oxidation is considered as an increase in the oxidation number of the carbon atoms, then reactions such as dehydrogenation, ammoxidation, cyclization or chlorination are all oxidation reactions. In this field, most of processes for the synthesis of important chemicals used vanadium oxide-...

  6. Co-Containing Mixed Oxides and Their Activity in Catalytic Decomposition of Nitrous Oxide

    Czech Academy of Sciences Publication Activity Database

    Obalová, L.; Jirátová, Květa; Kovanda, F.; Pacultová, K.; Lacný, Z.; Mikulová, Z.

    Praha : Process Engineering Publisher, 2004. s. 332. ISBN 80-86059-40-5. [International Congress of Chemical and Process Engineering CHISA 2004 /16./. 22.08.2004-26.08.2004, Praha] R&D Projects: GA ČR GA104/04/2116 Institutional research plan: CEZ:AV0Z4072921 Keywords : catalytic decomposition * mixed oxide s Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  7. Physicochemical properties and catalytic activity of metal tetraphenyl porphins in the oxidation of alkylaromatic hydrocarbons

    Science.gov (United States)

    Kobotaeva, N. S.; Skorokhodova, T. S.; Kokova, D. A.

    2013-06-01

    We consider the effect of complexing metal in a tetraphenylporphin molecule on its catalytic activity in oxidizing alkylaromatic hydrocarbons by molecular oxygen. The catalytic activity of metal porphyrins (Co, Cu, Zn, Mn, and In TPP) is found to depend on their oxidation potentials and the distribution of electron density in the molecule. The electron-donating compound imidazole is shown to affect the oxidation rate.

  8. Key parameters when developing carbonaceous materials for catalytic wet peroxide oxidation

    OpenAIRE

    Ribeiro, Rui; Silva, Adrián; Pastrana-Martínez, Luisa; Figueiredo, José; Faria, Joaquim; Gomes, Helder

    2014-01-01

    Catalytic wet peroxide oxidation (CWPO) is an advanced oxidation process, operated using simple equipment and mild operating conditians, in which highly oxidizing hydraxyl radicaIs (HO') are generated fram the catalytic decompasition af hydrogen peroxide (H,O,) [L 2). Sinee the report of Lüeking el ai. in 1998 [3], the develapment af suitab-Ie -carbonaceous materials (without any added metal phase) for CWPO has been intensively explored [4). lhe influenee of struetUfal and surr...

  9. Kinetics study on catalytic wet air oxidation of phenol by several metal oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    WAN Jia-feng; FENG Yu-jie; CAI Wei-min; YANG Shao-xia; SUN Xiao-jun

    2004-01-01

    Four metal oxide catalysts composed of copper (Cu), stannum (Sn), copper-stannum (Cu-Sn) and copper-cerium(Cu-Ce) respectively were prepared by the co-impregnation method, and γ-alumina(γ-Al2O3) is selected as support. A first-order kinetics model was established to study the catalytic wet air oxidation of phenol at different temperature when these catalysts were used. The model simulations are good agreement with present experimental data. Results showed that the reaction rate constants can be significantly increased when catalysts were used, and the catalyst of 6% Cu-10%Ce/γ-Al2O3 showed the best catalytic activity. This is consistent with the result of catalytic wet air oxidation of phenol and the COD removal can be arrived at 98.2% at temperature 210℃, oxygen partial pressure 3 MPa and reaction time 30 min. The activation energies of each reaction with different catalysts are nearly equal, which is found to be about 42 kJ/mol and the reaction in this study is proved to be kinetics control.

  10. Catalytic pleat filter bags for combined particulate separation and nitrogen oxides removal from flue gas streams

    International Nuclear Information System (INIS)

    The development of a high temperature catalytically active pleated filter bag with hybrid filter equipment for the combined removal of particles and nitrogen oxides from flue gas streams is presented. A special catalyst load in stainless steel mesh cartridge with a high temperature pleated filter bag followed by optimized catalytic activation was developed to reach the required nitrogen oxides levels and to maintain the higher collection efficiencies. The catalytic properties of the developed high temperature filter bags with hybrid filter equipment were studied and demonstrated in a pilot scale test rig and a demonstration plant using commercial scale of high temperature catalytic pleated filter bags. The performance of the catalytic pleated filter bags were tested under different operating conditions, such as filtration velocity and operating temperature. Moreover, the cleaning efficiency and residual pressure drop of the catalyst loaded cartridges in pleated filter bags were tested. As result of theses studies, the optimum operating conditions for the catalytic pleated filter bags are determined. (author)

  11. Oxidative dehydrogenation of propane over vanadium based catalysts supported on Y molecular sieve%Y分子筛负载V基催化剂的丙烷氧化脱氢性能

    Institute of Scientific and Technical Information of China (English)

    范爱鑫; 张聚华

    2016-01-01

    以 Y 分子筛为载体,采用浸渍法制备不同 V 含量的 V/ Y 系列催化剂,并考察其丙烷氧化脱氢制丙烯的催化性能。通过 BET、XRD、H2- TPR 和 NH3- TPD 等技术对催化剂的物化性能进行表征。结果表明,Y 分子筛具有大比表面积和窄孔径分布的特点,使负载的 V 能够形成高分散和孤立态V—O物种,负载的 V 物种堵塞了 Y 分子筛的小孔孔道,同时 Y 分子筛的弱酸性位有助于丙烷的吸附,对晶格氧活化丙烷起到了协同作用,负载 V 质量分数6%时,催化效果最好。%Using Y molecular sieve as the support,vanadium supported Y molecular sieve catalysts(V/ Y) with different vanadium contents were prepared by the impregnation method,and their catalytic perform-ance in the oxidative dehydrogenation of propane to propene was investigated. The catalysts were charac-terized by BET,XRD,H2-TPR and NH3-TPD. The results showed that Y molecular sieve possessed large specific surface area and narrow pore size distribution,which enabled vanadium to form highly dispersed and isolated state V—O species;the loading vanadium species blocked the small pore channels of Y molecular sieve;at the same time,the weak acid sites of Y molecular sieve was helpful to propane adsorp-tion,and had synergistic effect on propane activation by lattice oxygen. V/ Y catalyst with 6wt% vanadium exhibited better catalytic performance.

  12. Catalytic Oxidation of Methane into Methanol over Copper-Exchanged Zeolites with Oxygen at Low Temperature

    OpenAIRE

    Narsimhan, Karthik; Iyoki, Kenta; Dinh, Kimberly; Román-Leshkov, Yuriy

    2016-01-01

    The direct catalytic conversion of methane to liquid oxygenated compounds, such as methanol or dimethyl ether, at low temperature using molecular oxygen is a grand challenge in C–H activation that has never been met with synthetic, heterogeneous catalysts. We report the first demonstration of direct, catalytic oxidation of methane into methanol with molecular oxygen over copper-exchanged zeolites at low reaction temperatures (483–498 K). Reaction kinetics studies show sustained catalytic acti...

  13. Catalytic wet air oxidation of chlorophenols over supported ruthenium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Li Ning [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); Descorme, Claude [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)]. E-mail: claude.descorme@catalyse.cnrs.fr; Besson, Michele [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

    2007-07-31

    A series of noble metal (Pt, Pd, Ru) loaded zirconia catalysts were evaluated in the catalytic wet air oxidation (CWAO) of mono-chlorophenols (2-CP, 3-CP, 4-CP) under relatively mild reaction conditions. Among the investigated noble metals, Ru appeared to be the best to promote the CWAO of CPs as far as incipient-wetness impregnation was used to prepare all the catalysts. The position of the chlorine substitution on the aromatic ring was also shown to have a significant effect on the CP reactivity in the CWAO over 3 wt.% Ru/ZrO{sub 2}. 2-CP was relatively easier to degradate compared to 3-CP and 4-CP. One reason could be the higher adsorption of 2-CP on the catalyst surface. Further investigations suggested that 3 wt.% Ru/ZrO{sub 2} is a very efficient catalyst in the CWAO of 2-CP as far as high 2-CP conversion and TOC abatement could still be reached at even lower temperature (393 K) and lower total pressure (3 MPa). Additionally, the conversion of 2-CP was demonstrated to increase with the initial pH of the 2-CP solution. The dechlorination reaction is promoted at higher pH. In all cases, the adsorption of the reactants and the reaction intermediates was shown to play a major role. All parameters that would control the molecule speciation in solution or the catalyst surface properties would have a key effect.

  14. Preparation of USY zeolite VOx supported catalysts from V(AcAc)3 and NH4VO3. Catalytic properties for the dehydrogenation of n-butane in oxygen-free atmosphere.

    Science.gov (United States)

    Garcia, Elba M; Sanchez, Miguel D; Tonetto, Gabriela; Volpe, María A

    2005-12-01

    The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is discussed. The samples were prepared in order to obtain highly dispersed V-species, avoiding the formation of crystalline vanadia and the destruction of the zeolite framework. Two methods were employed for preparing VO(x)/USY samples: an organic route using V(AcAc)3 and an inorganic route using NH4VO3. The characterization of the samples was performed with XRD, TPR, NH3-TPD, and N2 isotherms. From these results it is concluded that when VO(x) is supported on the surface of USY from acidic aqueous solution of ammonium metavanadate, the destruction of the zeolite framework is accomplished. For higher pH values in the impregnating solution, undesired V2O5 is formed on the USY surface. On the other hand, VO(x)/USY prepared from the organic precursor shows no destruction of the USY structure. In addition, highly dispersed VO(x) are formed, though for relatively high V loadings (6%) an obstruction of the zeolite windows takes place. The samples are tested as catalysts for gas phase dehydrogenation of n-butane to olefins. The catalysts prepared from NH4VO3 are almost inactive for the reaction. On the other hand, both samples prepared from V(AcAc)3 present initial conversion levels in the 8-12% range. However, the selectivity depends on the V loading, the catalysts with 6% loading being the most selective (75%). The catalytic patterns of the samples (activity and selectivity) are in agreement with the physicochemical features of the VO(x)/USY surface. PMID:16023658

  15. Surface synergisms between copper and its oxides. I. Isopropanol dehydrogenation over unsupported CuO, Cu/sub 2/O, and Cu metal

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, J.; Al-Sayyed, G.H.; Cronin, J.A.; Fierro, J.L.G.; Healy, C.; Hirschwald, W.; Ilyas, M.; Tobin, J.P.

    1986-11-01

    Selective dehydrogenation of isopropanol, (-H/sub 2/), has been utilized over unsupported powdered samples of high purity Cu/sup II/O, Cu/sub 2//sup I/O, and Cu/sup 0/-metal in efforts to clarify the relative importance of these three valence states in the catalysis of hydrogen-handling reactions by copper catalysts. Comparisons are made of high exposure activity profiles, delineating the approach to pseudo-stationary-state levels of conversion to acetone, attained from CuO, Cu/sub 2/O, and Cu-metal starting materials under a continuous flow of isopropanol vapor at temperatures from 423 to 523 K. Highest activity and lowest lead-in time to attainment of the working state was observed with a physical mixture of CuO with prereduced Cu-metal. Initial state activities are compared using low exposure activity profiles, obtained by admission and detailed product analysis for each of a series of micropulses of isopropanol at 473 K. These low exposure activity profiles for CuO, Cu/sub 2/O, and Cu-metal, and their modification by mild surface prereduction, confirmed that significant ongoing (-H/sub 2/) activity only developed when oxidized and metallic copper locations were present simultaneously.

  16. Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

    Directory of Open Access Journals (Sweden)

    Vincenzo Vaiano

    2013-12-01

    Full Text Available In this work, the results of gas phase cyclohexane photocatalytic oxidative dehydrogenation on MoOx/SO4/TiO2 catalysts with DRIFTS analysis are presented. Analysis of products in the gas-phase discharge of a fixed bed photoreactor was coupled with in situ monitoring of the photocatalyst surface during irradiation with an IR probe. An interaction between cyclohexane and surface sulfates was found by DRIFTS analysis in the absence of UV irradiation, showing evidence of the formation of an organo-sulfur compound. In particular, in the absence of irradiation, sulfate species initiate a redox reaction through hydrogen abstraction of cyclohexane and formation of sulfate (IV species. In previous studies, it was concluded that reduction of the sulfate (IV species via hydrogen abstraction during UV irradiation may produce gas phase SO2 and thereby loss of surface sulfur species. Gas phase analysis showed that the presence of MoOx species, at same sulfate loading, changes the selectivity of the photoreaction, promoting the formation of benzene. The amount of surface sulfate influenced benzene yield, which decreases when the sulfate coverage is lower. During irradiation, a strong deactivation was observed due to the poisoning of the surface by carbon deposits strongly adsorbed on catalyst surface.

  17. Effect of gallium,aluminium,and chromium on silica supported V-Mg-O catalysts during oxidative dehydrogenation of propane:Kinetic study

    Institute of Scientific and Technical Information of China (English)

    B.Ravi Kumar; Rajeev Kumar

    2008-01-01

    The oxidative dehydrogenation(ODH)of propane was conducted on gallium,aluminum.and chromium doped Si30VMgO catalysts.On doping,the concentrations of the phases responsible for the activity and selectivity increased in their concentrations.The reaction studies were conducted in a tubular steel reactor at temperatures of 753,783,813.and 843 K and atmospheric pressure.The total flow rates of the feed were chosen as 30,40,50,and 60 ml/min.The propane to oxygen ratios were chosen at 1:1,2:1,and 3:1,respectively.The effect of various dopants on the activity and selectivity of the catalysts was studied.Deactivation studies were conducted over all the catalysts.The kinetic data were analyzed in terms of power law models and Langmuir-Hinshelwood(LH)models.The kinetic data results were analyzed by comparing the effect of dopants.Statistical model discrimination was done for the proposed models.AIC and BIC criteria were used for discrimination of the models.

  18. Reaction pathways for catalytic gas-phase oxidation of glycerol over mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Suprun, W.; Glaeser, R.; Papp, H. [Leipzig Univ. (Germany). Inst. of Chemical Technology

    2011-07-01

    Glycerol as a main by-product from bio-diesel manufacture is a cheap raw material with large potential for chemical or biochemical transformations to value-added C3-chemicals. One possible way of glycerol utilization involves its catalytic oxidation to acrylic acid as an alternative to petrochemical routes. However, this catalytic conversion exhibits various problems such as harsh reaction conditions, severe catalyst coking and large amounts of undesired by-products. In this study, the reaction pathways for gas-phase conversion of glycerol over transition metal oxides (Mo, V und W) supported on TiO{sub 2} and SiO{sub 2} were investigated by two methods: (i) steady state experiments of glycerol oxidation and possible reactions intermediates, i.e., acrolein, 3-hydroxy propionaldehyde and acetaldehyde, and (ii) temperature-programmed surface reaction (TPSR) studies of glycerol conversion in the presence and in the absence of gas-phase oxygen. It is shown that the supported W-, V and Mo-oxides possess an ability to catalyze the oxidation of glycerol to acrylic acid. These investigations allowed us to gain a deeper insight into the reaction mechanism. Thus, based on the obtained results, three possible reactions pathways for the selective oxidation of glycerol to acrylic acid on the transition metal-containing catalysts are proposed. The major pathways in presence of molecular oxygen are a fast successive destructive oxidation of glycerol to CO{sub x} and the dehydration of glycerol to acrolein which is a rate-limiting step. (orig.)

  19. Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

    DEFF Research Database (Denmark)

    Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram;

    2012-01-01

    Pd/Al2O3 catalysts oscillate between ignition and extinction of the catalytic partial oxidation of methane when they are exposed to a 2:1 reaction mixture of methane and oxygen. The oscillations of the catalytic performance and the structure of Pd/Al2O3 catalysts in a fixed-bed reactor were...... combination of total oxidation and reforming in the catalytic capillary reactor was observed. This change in catalytic performance was directly linked to changes in the oxidation state of the Pd/Al2O3 catalysts at different positions along the catalytic reactor. During the ignition of the catalytic partial...

  20. Preparation, characterization and catalytic performance of Mo-V-O oxide layers linked by alkylamines.

    Science.gov (United States)

    Wang, Feng; Ueda, Wataru

    2009-03-01

    Thin layers of alkylamine-stabilized molybdenum vanadium complex oxide were prepared under hydrothermal condition; these materials exhibited 10-60 times higher catalytic activities than pure crystalline Mo-V-O oxide in the selective oxidation of alcohols. PMID:19225642

  1. Effect of Impregnation Solvent on Catalytic Performance of Pt-Sn/SBA-15 in Propane Dehydrogenation%浸渍溶剂对Pt-Sn/SBA-15催化剂丙烷脱氢性能的影响

    Institute of Scientific and Technical Information of China (English)

    冯静; 张明森; 杨元一

    2013-01-01

    The effects of the preparation conditions of Pt-Sn/SBA-15 catalysts on their catalytic performance in propane dehydrogenation were investigated.The catalysts were prepared by dissolving the salts of active ingredients in distilled water or ethanol and then impregnating the SBA-15 molecular sieve support with the salt solutions.The results showed that the solvents affected the catalyst performance notably.The supports and catalysts were characterized by means of XRD,BET and CO pulse adsorption.The results showed that the catalysts had different structure and specific activity.The catalyst prepared by the impregnation with aqueous solutions of tin dichloride and chloroplatinic acid has the best catalytic performance.In the aqueous solutions,chloroplatinic acid can ionize into hydrions and chloroplatinic acid radical anions,and in the ethanol solutions,chloroplatinic acid still exists in the form of molecular,which leads to the very different metal dispersity on the Pt-Sn/SBA-15catalysts.%以乙醇和水为溶剂配制相应活性组分盐溶液作为浸渍液,研究了不同条件下制备的Pt-Sn/SBA-15催化剂用于丙烷脱氢时的催化性能;采用XRD、BET、TEM和CO脉冲吸附等方法对载体和催化剂进行了表征.实验结果表明,浸渍溶剂对Pt-Sn/SBA-15催化剂性能的影响显著,以氯化亚锡水溶液浸渍Sn、以氯铂酸水溶液浸渍Pt的催化剂性能最好.Sn浸渍液的溶剂对催化剂结构影响不明显,而Pt浸渍液的溶剂不同时催化剂的Pt分散度有显著差异.在水溶液中,氯铂酸可电离成氢阳离子和氯铂酸根阴离子,离子在水中分散存在;而在乙醇溶液中,由于乙醇极性比水差,氯铂酸不电离形成离子,仍以分子形式存在并容易团聚,从而导致氯铂酸水溶液和乙醇溶液浸渍后的Pt-Sn/SBA-15催化剂的Pt分散度有较大差异.

  2. Size Effect of Gold Sol/γ-Alumina on the Catalytic Activities of CO Oxidation

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-Hua; GAO Geng-Yu

    2006-01-01

    The relationship between particle size and catalytic activity of gold nanoparticle catalysts with γ-Al2O3 as support has been investigated. The catalysts were prepared via the gold sol with different particle sizes by micelle method, and their structures were characterized by HRTEM and XRD, respectively. Furthermore, the catalytic activities were tested by CO oxidation. Experimental results showed that the catalytic activity became much weaker when gold particles were increased from 3.2 to 6.6 nm. Additionally, the particle size was also a key factor to govern catalytic activity with regard to gold supported on TiO2 prepared by the methods of deposition-precipitation.

  3. Reducing-Agent-Free Instant Synthesis of Carbon-Supported Pd Catalysts in a Green Leidenfrost Droplet Reactor and Catalytic Activity in Formic Acid Dehydrogenation

    Science.gov (United States)

    Lee, Dong-Wook; Jin, Min-Ho; Lee, Young-Joo; Park, Ju-Hyoung; Lee, Chun-Boo; Park, Jong-Soo

    2016-05-01

    The development of green synthesis methods for supported noble metal catalysts remains important challenges to improve their sustainability. Here we first synthesized carbon-supported Pd catalysts in a green Leidenfrost droplet reactor without reducing agents, high-temperature calcination and reduction procedures. When the aqueous solution containing Pd nitrate precursor, carbon support, and water is dripped on a hot plate, vapor layer is formed between a solution droplet and hot surface, which allow the solution droplet to be levitated on the hot surface (Leidenfrost phenomena). Subsequently, Pd nanoparticles can be prepared without reducing agents in a weakly basic droplet reactor created by the Leidenfrost phenomena, and then the as-prepared Pd nanoparticles are loaded on carbon supports during boiling down the droplet on hot surface. Compared to conventional incipient wetness and chemical synthetic methods, the Leidenfrost droplet reactor does not need energy-consuming, time-consuming, and environmentally unfriendly procedures, which leads to much shorter synthesis time, lower carbon dioxide emission, and more ecofriendly process in comparison with conventional synthesis methods. Moreover, the catalysts synthesized in the Leidenfrost droplet reactor provided much better catalytic activity for room-temperature formic acid decomposition than those prepared by the incipient wetness method.

  4. CATALYTIC WET AIR OXIDATION OF INDUSTRIAL EFFLUENTS USING A Pt CATALIST SUPPORTED ON MULTIWALLED CARBON NANOTUBES

    OpenAIRE

    Gabriel Ovejero; José L. Sotelo; Araceli Rodríguez; Ana Vallet; Juan García

    2011-01-01

    In this work, catalytic wet air oxidation in a batch reactor was studied by catalytic wet air oxidation to treat industrial wastewater. Basic Yellow 11, a basic dye, was employed as a model compound and platinum supported over multi-walled nanotubes (Pt/MWNT) was used as catalyst. Additionally, two different industrial wastewaters were tested. The results prove the high effectivity of this treatment, showing high extents of total organic carbon and toxicity removal of the final effluent. We c...

  5. Effects of Gas Velocity and Temperature on Nitric Oxide Conversion in Simulated Catalytic Converter

    OpenAIRE

    Sathaporn Chuepeng

    2012-01-01

    Problem statement: Gaseous emissions from gasoline engine such as carbon monoxide, unburned hydrocarbon and nitrogen oxides were usually reduced in three-way catalytic converter simultaneously around theoretical fuel and air combustion. Engine speed and load and other parameters were varied over a wide range of operating conditions, resulting in different exhaust gas composition and condition intake into catalytic converter. This work was studied the conversion of Nitric Oxide (NO) in exhaust...

  6. An experimental survey of additives for improving dehydrogenation properties of magnesium hydride

    Science.gov (United States)

    Zhou, Chengshang; Fang, Zhigang Zak; Sun, Pei

    2015-03-01

    The use of a wide range of additives has been known as an important method for improving hydrogen storage properties of MgH2. There is a lack of a standard methodology, however, that can be used to select or compare the effectiveness of different additives. A systematic experimental survey was carried out in this study to compare a wide range of additives including transitions metals, transition metal oxides, hydrides, intermetallic compounds, and carbon materials, with respect to their effects on dehydrogenation properties of MgH2. MgH2 with various additives were prepared by using a high-energy-high-pressure planetary ball milling method and characterized by using thermogravimetric analysis (TGA) techniques. The results showed that additives such as Ti and V-based metals, hydride, and certain intermetallic compounds have strong catalytic effects. Additives such as Al, In, Sn, Si showed minor effects on the kinetics of the dehydrogenation of MgH2, while exhibiting moderate thermodynamic destabilizing effects. In combination, MgH2 with both kinetic and thermodynamic additives, such as the MgH2-In-TiMn2 system, exhibited a drastically decreased dehydrogenation temperature.

  7. Effects of carrier and Mn loading on supported manganese oxide catalysts for catalytic combustion of methane

    Institute of Scientific and Technical Information of China (English)

    Jinyan Hu; Wei Chu; Limin Shi

    2008-01-01

    Supported manganese oxide catalysts were prepared by incipient wetness impregnation method for methane cat-alytic combustion, and effects of the support (Al2O3, SiO2 and TiO2) and Mn loading were investigated. These catalysts were characterized with N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction techniques. Methane conversion varied in a large range depending on supports or Mn loading. Al2O3 supported 15% Mn cata-lyst exhibited better activity toward methane catalytic oxidation. The manganese state and oxygen species played an important role in the catalytic performance.

  8. UV-Shielding and Catalytic Characteristics of Nanoscale Zinc-Cerium Oxides

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fine particles of zinc-cerium oxides (ZCO) used as an ultraviolet filter were prepared via combustion synthesis route. The catalytic activity, UV-shielding performance, surface modification and application of ZCO in polyester varnish were discussed in detail. The experimental results indicate that the photo-catalytic activity of ZCO is much smaller than these of ZnO and TiO2; the oxidation catalytic activity of ZCO is far lower than that of CeO2; the ZCO has shown excellent ultraviolet absorption in the range of UV;addition modified ZCO (MZCO) into polyester will enhance the UV-shielding capability of polyester.

  9. Structure and reactivity of surface oxides on Pt(110) during catalytic CO oxidation

    OpenAIRE

    Ackermann, M. D.; Pedersen, T. M.; Hendriksen, B.L.M.; ROBACH, O.; Bobaru, S. C.; Quiros, C.; Kim, H.; Hammer, B; Ferrer Fàbregas, Salvador; Frenke, J. W. M.

    2005-01-01

    We present the first structure determination by surface x-ray diffraction during the restructuring of a model catalyst under reaction conditions, i.e., at high pressure and high temperature, and correlate the restructuring with a change in catalytic activity. We have analyzed the Pt(110) surface during CO oxidation at pressures up to 0.5 bar and temperatures up to 625 K. Depending on the O2/CO pressure ratio, we find three well-defined structures: namely, (i) the bulk-terminated Pt(110) surfa...

  10. Catalytic soot oxidation over Ce- and Cu-doped hydrotalcites-derived mesoporous mixed oxides.

    Science.gov (United States)

    Wang, Zhongpeng; Wang, Liguo; He, Fang; Jiang, Zheng; Xiao, Tiancun; Zhang, Zhaoliang

    2014-09-01

    Ce- and Cu-doped hydrotalcites derived mixed oxides were prepared through co-precipitation and calcination method, and their catalytic activities for soot oxidation with O2 and O2/NO were investigated. The solids were characterized by XRD, TG-DTG, BET, H2-TPR, in situ FTIR and TPO techniques. All the catalysts precursors showed the typical diffraction patterns of hydrotalcite-like materials having layered structure. The derived mixed oxides exhibited mesoporous properties with specific surface area of 45-160 m2/g. After both Ce and Cu incorporated, mixed crystalline phases of CuO (tenorite), CeO2 (fluorite) and MgAl2O4 (spinel) were formed. As a result, the NO(x) adsorption capacity of this catalyst was largely increased to 201 μmol/g, meanwhile, it was also the most effective to convert NO into NO2 in the sorption process due to the enhanced reducibility. The in situ FTIR spectra revealed that NO(x) were stored mainly as chelating bidentate and monodentate nitrate. The interaction effect between Cu and Ce in the mixed oxide resulted in different NO(x) adsorption behavior. Compared with the non-catalyzed soot oxidation, soot conversion curves over the mixed oxides catalysts shift to low temperature in O2. The presence of NO in the gas phase significantly enhanced the soot oxidation activity with ignition temperature decreased to about 320 degrees C, which is due to NO conversion to NO2 over the catalyst followed by the reaction of NO2 with soot. This explains the cooperative effect of Ce and Cu in the mixed oxide on soot oxidation with high activity and 100% selectivity to CO2 formation. PMID:25924375

  11. Elementary steps of the catalytic NO{sub x} reduction with NH{sub 3}: Cluster studies on reaction paths and energetics at vanadium oxide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, M.; Hermann, K. [Inorganic Chemistry Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

    2013-12-28

    We consider different reaction scenarios of the selective catalytic reduction (SCR) of NO in the presence of ammonia at perfect as well as reduced vanadium oxide surfaces modeled by V{sub 2}O{sub 5}(010) without and with oxygen vacancies. Geometric and energetic details as well as reaction paths are evaluated using extended cluster models together with density-functional theory. Based on earlier work of adsorption, diffusion, and reaction of the different surface species participating in the SCR we confirm that at Brønsted acid sites (i.e., OH groups) of the perfect oxide surface nitrosamide, NH{sub 2}NO, forms a stable intermediate. Here adsorption of NH{sub 3} results in NH{sub 4} surface species which reacts with gas phase NO to produce the intermediate. Nitrosamide is also found as intermediate of the SCR near Lewis acid sites of the reduced oxide surface (i.e., near oxygen vacancies). However, here the adsorbed NH{sub 3} species is dehydrogenated to surface NH{sub 2} before it reacts with gas phase NO to produce the intermediate. The calculations suggest that reaction barriers for the SCR are overall higher near Brønsted acid sites of the perfect surface compared with Lewis acid sites of the reduced surface, examined for the first time in this work. The theoretical results are consistent with experimental findings and confirm the importance of surface reduction for the SCR process.

  12. Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

    International Nuclear Information System (INIS)

    High value-added aromatic aldehydes (e. g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide (H2O2) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin (Co(TPPS4)) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without Co(TPPS4). Moreover, a possible mechanism of HFBO oxidation using Co(TPPS4)/H2O2 was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under Co(TPPS4)/H2O2 system

  13. Magnetic carbon xerogels for the catalytic wet peroxide oxidation of 4-nitrophenol solutions

    OpenAIRE

    Ribeiro, R; Silva, Adrián; Faria, Joaquim; Gomes, Helder

    2015-01-01

    Catalytic wet peroxide oxidation (CWPO) is a well-known advanced oxidation process for the removal of organic pollutants from industrial process waters and wastewater. Specifically, CWPO employs hydrogen peroxide (H2O2) as oxidation source and a suitable catalyst to promote its decomposition via formation of hydroxyl radicals (HO•), which exhibit high oxidizing potential and serve as effective species in the destruction of a huge range of organic pollutants

  14. Preparation of rare-earth metal complex oxide catalysts for catalytic wet air oxidation

    Institute of Scientific and Technical Information of China (English)

    LI Ning; LI Guangming; YAO Zhenya; ZHAO Jianfu

    2007-01-01

    Catalytic wet air oxidation(CWAO)is one of the most promising technologies for pollution abatement.Developing catalysts with high activity and stability is crucial for the application of the CWAO process.The Mn/Ce complex oxide catalyrsts for CWAO of high concentration phenol containing wastewater were prepared by coprecipitation.The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis.The Mn/Ce serial catalysts were characterized by Brunauer-Emmett-Teller(BET)analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry(ICP-AES).The results show that the catalysts have high catalytic activities even at a low temperature(80℃)and low oxygen partial pressure(0.5 MPa)in a batch reactor.The metallic ion leaching is comparatively low(Mn<6.577 mg/L and Ce<0.6910 mg/L,respectively)in the CWAO process.The phenol,CODCD and TOC removal efficiencies in the solution exceed 98.5% using the optimal catalyst(named CSP).The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater.

  15. Catalytic performance and structural characterization of ferric oxide and its composite oxides supported gold catalysts for low-temperature CO oxidation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The preparation and catalytic activity of ferric oxide and its composite oxides supported gold catalysts for Iow-temperature CO oxidation were investigated detailedly, and characterized extensively by XRD, XPS, TPR, EC and XAFS techniques. It was found that containing highly dis persed Au of partially oxidized state, these nano-structured oxides supported Au/Fe2O3 and Au/NiFe2O4 catalysts had higher Iow-temperature activities. The possible catalytic active center is the gold of partially oxidized state (Auζ+).

  16. Selective catalytic oxidation of H2S over iron oxide supported on alumina-intercalated Laponite clay catalysts

    International Nuclear Information System (INIS)

    Graphical abstract: The catalytic reaction and deactivation mechanisms for H2S selective oxidation over Fe/Al-Lap catalysts are shown in the illustration. The catalytic reaction follows Mars–van Krevelen mechanism. Moreover, the interaction between iron oxide and alumina, the strong acidity of the catalysts and the well dispersion of iron oxide improve the catalytic performance efficiently. Meanwhile, the catalyst deactivation is mainly due to the formation of Fe2(SO4)3 and elemental sulfur deposits on the surface. -- Highlights: • Fe/Al-Lap catalysts with mesoporous structure were synthesized. • Iron oxide mainly exists in form of isolate Fe3+ in an oxidic environment. •Fe/Al-Lap catalysts show high catalytic activities at low temperature. •The high catalytic activities are ascribed to the interaction between iron oxide and alumina. •The formed Fe2(SO4)3 and elemental sulfur deposits on surface cause catalyst deactivation. -- Abstract: A series of iron oxide supported on alumina-intercalated clay catalysts (named Fe/Al-Lap catalysts) with mesoporous structure and high specific surface area were prepared. The structural and chemical properties were studied by nitrogen sorption isotherms, X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis DRS), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FTIR), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) techniques. It was realized that iron oxide mainly existed in the form of isolated Fe3+ in an oxidic environment. Fe/Al-Lap catalysts showed high catalytic activities in the temperature range of 120–200 °C without the presence of excessive O2. This can be attributed to the interaction between iron oxide and alumina, which improve the redox property of Fe3+ efficiently. In addition, the strong acidity of catalysts and good dispersion of iron oxide were also beneficial to oxidation reaction. Among them, 7% Fe

  17. Metal-Free Oxidation of Primary Amines to Nitriles through Coupled Catalytic Cycles.

    Science.gov (United States)

    Lambert, Kyle M; Bobbitt, James M; Eldirany, Sherif A; Kissane, Liam E; Sheridan, Rose K; Stempel, Zachary D; Sternberg, Francis H; Bailey, William F

    2016-04-01

    Synergism among several intertwined catalytic cycles allows for selective, room temperature oxidation of primary amines to the corresponding nitriles in 85-98 % isolated yield. This metal-free, scalable, operationally simple method employs a catalytic quantity of 4-acetamido-TEMPO (ACT; TEMPO=2,2,6,6-tetramethylpiperidine N-oxide) radical and the inexpensive, environmentally benign triple salt oxone as the terminal oxidant under mild conditions. Simple filtration of the reaction mixture through silica gel affords pure nitrile products. PMID:26868873

  18. Advances and perspectives in catalytic oxidation of hydrocarbons in liquid phase

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This review article summarizes recent advances in catalytic oxidation of hydrocarbons, especially presents two strategies for activation of C-H bonds or molecular oxygen. Based on our own research results, the applications of the two methods in the oxidation of cyclohexane, toluene and ethyl benzene, etc. are introduced, and the perspectives of the two methods are also discussed.

  19. Formation of high surface area Li/MgO—Efficient catalyst for the oxidative dehydrogenation/cracking of propane

    NARCIS (Netherlands)

    Trionfetti, C.; Babich, I.V.; Seshan, K.; Lefferts, L.

    2006-01-01

    In this study nanoscale clusters of Li/MgO oxide with varying lithium contents are prepared via the sol–gel method. The preparation routine consists of co-gelation of LiNO3 and Mg(OCH3)2 in methanol/water solution followed by drying at 50 °C under vacuum and calcination at 500 °C in air. The structu

  20. TiO2-sludge carbon enhanced catalytic oxidative reaction in environmental wastewaters applications.

    Science.gov (United States)

    Athalathil, Sunil; Erjavec, Boštjan; Kaplan, Renata; Stüber, Frank; Bengoa, Christophe; Font, Josep; Fortuny, Agusti; Pintar, Albin; Fabregat, Azael

    2015-12-30

    The enhanced oxidative potential of sludge carbon/TiO2 nano composites (SNCs), applied as heterogeneous catalysts in advanced oxidation processes (AOPs), was studied. Fabrification of efficient SNCs using different methods and successful evaluation of their catalytic oxidative activity is reported for the first time. Surface modification processes of hydrothermal deposition, chemical treatment and sol-gel solution resulted in improved catalytic activity and good surface chemistry of the SNCs. The solids obtained after chemical treatment and hydrothermal deposition processes exhibit excellent crystallinity and photocatalytic activity. The highest photocatalytic rate was obtained for the material prepared using hydrothermal deposition technique, compared to other nanocomposites. Further, improved removal of bisphenol A (BPA) from aqueous phase by means of catalytic ozonation and catalytic wet air oxidation processes is achieved over the solid synthesized using chemical treatment method. The present results demonstrate that the addition of TiO2 on the surface of sludge carbon (SC) increases catalytic oxidative activity of SNCs. The latter produced from harmful sludge materials can be therefore used as cost-effective and efficient sludge derived catalysts for the removal of hazardous pollutants. PMID:26223014

  1. Selective catalytic reduction of NO with NH{sub 3} at V{sub 2}O{sub 5}(010) and silica supported vanadium oxide: DFT studies

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Mathis; Hermann, Klaus [Fritz-Haber-Institut der MPG, Sfb 546, Berlin (Germany)

    2011-07-01

    The selective catalytic reduction (SCR) of NO{sub x} with NH{sub 3} over vanadium based metal-oxide (VO{sub x}) catalysts has been proven to be one of the most effective NO{sub x} reduction processes. Details of the reaction mechanism are still under debate. Adsorption, (de)hydrogenation, reactions with NO, and surface water formation at the VO{sub x} catalyst contribute elementary steps. These processes are examined in theoretical studies employing density-functional theory together with gradient corrected functionals. The VO{sub x} substrate is modeled by clusters cut out from the clean V{sub 2}O{sub 5}(010) surface where peripheral oxygen bonds are saturated by hydrogen. Reduced surfaces are represented by introducing oxygen vacancies. In addition, silica supported vanadium oxide clusters are considered. NH{sub 3} is found to interact with the clean V{sub 2}O{sub 5}(010) surface only in the presence of OH groups (Boernsted acid sites) where it can form a rather stable surface NH{sub 4}{sup +} species. Further, NH{sub 3} can adsorb at vanadium centers of lower coordination at the reduced surface (Lewis acid sites). This leads to two different SCR reaction scenarios transferring NH{sub 3} and NO to N{sub 2} and H{sub 2}O which are discussed by corresponding reaction paths and intermediates.

  2. Selective Catalytic Oxidation of NH3 to N2 for Catalytic Combustion of Low Heating Value Gas under Lean/Rich Conditions

    Czech Academy of Sciences Publication Activity Database

    Kušar, H.M.J.; Ersson, A.G.; Vosecký, Martin; Järas, S.G.

    2005-01-01

    Roč. 58, 1-2 (2005), s. 25-32. ISSN 0926-3373 Institutional research plan: CEZ:AV0Z40720504 Keywords : catalytic combustion * selective catalytic oxidation * ammonia Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.809, year: 2005

  3. Selective catalytic reduction of nitrogen oxides with ammonia over microporous zeolite catalysts

    OpenAIRE

    VENNESTROM, PETER NICOLAI RAVNBORG

    2014-01-01

    With increasing legislative demands to remove nitrogen oxides (NOx) from automotive diesel exhaust, new catalyst systems are investigated and intensely studied in industry as well in academia. The most prevailing catalytic method of choice is the selective catalytic reduction (SCR) where non-toxic urea is used as a reductant for practical reasons. Usually urea is stored in a separate tank and once injected into the exhaust system it hydrolyses into the more aggressive reductant NH3 and CO2. ...

  4. Catalytic Dehydrogenation over Pd-Supported ZSM-5 Zeolite for o-Phenylphenol Synthesis%载钯ZSM-5分子筛催化脱氢合成邻苯基苯酚

    Institute of Scientific and Technical Information of China (English)

    蔡春; 吕春绪

    2001-01-01

    Pd-supported ZSM-5 zeolites prepared through ion exchange technique were used as a dehydrogenation catalyst for synthesis of o-phenylphenol from cyclohexanone. When Si/A1 ratio in the catalyst was 85: 1 or more, an obvious reduction in attenuation rate of catalyst activity was observed.When the Si/Al ratio was of 17 . 1 or less, polymer compounds could be formed on the surface of zeolite, that would decrease the dehydrogenation activity due to the reduction of the specific surface area of the catalyst.

  5. Catalytic oxidative pyrolysis of spent organic ion exchange resins from nuclear power plants

    International Nuclear Information System (INIS)

    The spent IX resins from nuclear power reactors are highly active solid wastes generated during operations of nuclear reactors. Catalytic oxidative pyrolysis of these resins can lead to high volume reduction of these wastes. Low temperature pyrolysis of transition metal ion loaded IX resins in presence of nitrogen was carried out in order to optimize catalyst composition to achieve maximum weight reduction. Thermo gravimetric analysis of the pyrolysis residues was carried out in presence of air in order to compare the oxidative characteristics of transition metal oxide catalysts. Copper along with iron, chromium and nickel present in the spent IX resins gave the most efficient catalyst combination for catalytic and oxidative pyrolysis of the residues. During low temperature catalytic pyrolysis, 137Cesium volatility was estimated to be around 0.01% from cationic resins and around 0.1% from anionic resins. During oxidative pyrolysis at 700 degC, nearly 10 to 40% of 137Cesium was found to be released to off gases depending upon type of resin and catalyst loaded on to it. The oxidation of pyrolytic residues at 700 degC gave weight reduction of 15% for cationic resins and 93% for anionic resins. Catalytic oxidative pyrolysis is attractive for reducing weight and volume of spent cationic resins from PHWRs and VVERs. (author)

  6. Biodiesel by catalytic reactive distillation powered by metal oxides

    NARCIS (Netherlands)

    A.A. Kiss; A.C. Dimian; G. Rothenberg

    2008-01-01

    The properties and use of biodiesel as a renewable fuel as well as the problems associated with its current production processes are outlined. A novel sustainable esterification process based on catalytic reactive distillation is proposed. The pros and cons of manufacturing biodiesel via fatty acid

  7. Dehydration, Dehydrogenation, and Condensation of Alcohols on Supported Oxide Catalysts Based on Cyclic (WO3)3 and (MoO3)3 Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, Roger J.; Dixon, David A.; Kay, Bruce D.; Dohnalek, Zdenek

    2014-01-01

    Supported early transition metal oxides have important applications in numerous catalytic reactions. In this article we review preparation and activity of well-defined model WO3 and MoO3 catalysts prepared via deposition of cyclic gas-phase (WO3)3 and (MoO3)3 clusters generated by sublimation of WO3 and MoO3 powders. Conversion of small aliphatic alcohols to alkenes, aldehydes/ketons, and ethers is employed to probe the structure-activity relationships on model WO3 and MoO3 catalysts ranging from unsupported (WO3)3 and (MoO3)3 clusters embedded in alcohol matrices, to (WO3)3 clusters supported on surfaces of other oxides, and epitaxial and nanoporous WO3 films. Detailed theoretical calculations reveal the underlying reaction mechanisms and provide insight into the origin of the differences in the WO3 and MoO3 reactivity. For the range of interrogated (WO3)3 they further shed light into the role structure and binding of (WO3)3 clusters with the support play in determining their catalytic activity.

  8. Heterogeneous selective oxidation of formaldehyde over oxide catalysts. 2. Catalytic properties of V-Ti-oxide catalysts

    International Nuclear Information System (INIS)

    Catalytic properties of V-Ti-O-system and individual oxides V2O5 and TiO2 are investigated in reaction of formaldehyde oxidation within temperature range 120-160 deg C. Formic acid is the main product of formaldehyde oxidation on V2O5 and V-TiO-samples containing more than 5 mass% of V2O5, CO, CO2 and methyl formate form in small amounts. Selectivity with respect to formic acid for samples with 10-75 % V2O5-9025 % TiO2 composition in the conversion range 10-75 % at temperature 120 deg C is constant and comprises 98-93 %. V2O5 has high selectivity but low activity. (author)

  9. Influence of physicochemical treatments on iron-based spent catalyst for catalytic oxidation of toluene.

    Science.gov (United States)

    Kim, Sang Chai; Shim, Wang Geun

    2008-06-15

    The catalytic oxidation of toluene was studied over an iron-based spent and regenerated catalysts. Air, hydrogen, or four different acid solutions (oxalic acid (C2H2O4), citric acid (C6H8O7), acetic acid (CH3COOH), and nitric acid (HNO3)) were employed to regenerate the spent catalyst. The properties of pretreated spent catalyst were characterized by the Brunauer Emmett Teller (BET), inductively coupled plasma (ICP), temperature programmed reduction (TPR), and X-ray diffraction (XRD) analyses. The air pretreatment significantly enhanced the catalytic activity of the spent catalyst in the pretreatment temperature range of 200-400 degrees C, but its catalytic activity diminished at the pretreatment temperature of 600 degrees C. The catalytic activity sequence with respect to the air pretreatment temperatures was 400 degrees C>200 degrees C>parent>600 degrees C. The TPR results indicated that the catalytic activity was correlated with both the oxygen mobility and the amount of available oxygen on the catalyst. In contrast, the hydrogen pretreatment had a negative effect on the catalytic activity, and toluene conversion decreased with increasing pretreatment temperatures (200-600 degrees C). The XRD and TPR results confirmed the formation of metallic iron which had a negative effect on the catalytic activity with increasing pretreatment temperature. The acid pretreatment improved the catalytic activity of the spent catalyst. The catalytic activity sequence with respect to different acids pretreatment was found to be oxalic acid>citric acid>acetic acid>or=nitric acid>parent. The TPR results of acid pretreated samples showed an increased amount of available oxygen which gave a positive effect on the catalytic activity. Accordingly, air or acid pretreatments were more promising methods of regenerating the iron-based spent catalyst. In particular, the oxalic acid pretreatment was found to be most effective in the formation of FeC2O4 species which contributed highly to the

  10. Influence of physicochemical treatments on iron-based spent catalyst for catalytic oxidation of toluene

    International Nuclear Information System (INIS)

    The catalytic oxidation of toluene was studied over an iron-based spent and regenerated catalysts. Air, hydrogen, or four different acid solutions (oxalic acid (C2H2O4), citric acid (C6H8O7), acetic acid (CH3COOH), and nitric acid (HNO3)) were employed to regenerate the spent catalyst. The properties of pretreated spent catalyst were characterized by the Brunauer Emmett Teller (BET), inductively coupled plasma (ICP), temperature programmed reduction (TPR), and X-ray diffraction (XRD) analyses. The air pretreatment significantly enhanced the catalytic activity of the spent catalyst in the pretreatment temperature range of 200-400 deg. C, but its catalytic activity diminished at the pretreatment temperature of 600 deg. C. The catalytic activity sequence with respect to the air pretreatment temperatures was 400 deg. C > 200 deg. C > parent > 600 deg. C. The TPR results indicated that the catalytic activity was correlated with both the oxygen mobility and the amount of available oxygen on the catalyst. In contrast, the hydrogen pretreatment had a negative effect on the catalytic activity, and toluene conversion decreased with increasing pretreatment temperatures (200-600 deg. C). The XRD and TPR results confirmed the formation of metallic iron which had a negative effect on the catalytic activity with increasing pretreatment temperature. The acid pretreatment improved the catalytic activity of the spent catalyst. The catalytic activity sequence with respect to different acids pretreatment was found to be oxalic acid > citric acid > acetic acid ≥ nitric acid > parent. The TPR results of acid pretreated samples showed an increased amount of available oxygen which gave a positive effect on the catalytic activity. Accordingly, air or acid pretreatments were more promising methods of regenerating the iron-based spent catalyst. In particular, the oxalic acid pretreatment was found to be most effective in the formation of FeC2O4 species which contributed highly to the

  11. CO catalytic oxidation on iron-embedded monolayer MoS2

    International Nuclear Information System (INIS)

    Highlights: • CO catalytic oxidation on the Fe-embedded monolayer MoS2 has been studied. • Fe atom can be strongly constrained at the S vacancy of monolayer MoS2. • Fe-embedded monolayer MoS2 shows high catalytic activity toward CO oxidation. - Abstract: Based on first-principles calculations, the CO catalytic oxidation on the Fe-embedded monolayer MoS2 (Fe-MoS2) was investigated. It is found that Fe atom can be strongly constrained at the S vacancy of monolayer MoS2 with a high diffusion barrier. The CO oxidation reaction proceeds via a two-step mechanism with the highest energy barrier of 0.51 eV, which is started by the Langmuir–Hinshelwood reaction and ended by the Eley–Rideal reaction. The high catalytic activity of the Fe-MoS2 system may be attributed to the charge transfer and the orbital hybridization between the adsorbates and the Fe atom. This study proposes that embedding transition-metals is a promising way for making the basal plane of monolayer MoS2 catalytically active

  12. CO catalytic oxidation on iron-embedded monolayer MoS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Dongwei, E-mail: dwmachina@126.com [School of Physics, Anyang Normal University, Anyang, Henan 455000 (China); Tang, Yanan [Department of Physics and Electronic Science, Zhengzhou Normal University, Zhengzhou, Henan 450044 (China); Yang, Gui; Zeng, Jun [School of Physics, Anyang Normal University, Anyang, Henan 455000 (China); He, Chaozheng [Physics and Electronic Engineering College, Nanyang Normal University, Nanyang 473061 (China); Lu, Zhansheng [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China)

    2015-02-15

    Highlights: • CO catalytic oxidation on the Fe-embedded monolayer MoS{sub 2} has been studied. • Fe atom can be strongly constrained at the S vacancy of monolayer MoS{sub 2}. • Fe-embedded monolayer MoS{sub 2} shows high catalytic activity toward CO oxidation. - Abstract: Based on first-principles calculations, the CO catalytic oxidation on the Fe-embedded monolayer MoS{sub 2} (Fe-MoS{sub 2}) was investigated. It is found that Fe atom can be strongly constrained at the S vacancy of monolayer MoS{sub 2} with a high diffusion barrier. The CO oxidation reaction proceeds via a two-step mechanism with the highest energy barrier of 0.51 eV, which is started by the Langmuir–Hinshelwood reaction and ended by the Eley–Rideal reaction. The high catalytic activity of the Fe-MoS{sub 2} system may be attributed to the charge transfer and the orbital hybridization between the adsorbates and the Fe atom. This study proposes that embedding transition-metals is a promising way for making the basal plane of monolayer MoS{sub 2} catalytically active.

  13. Low-temperature plasma-catalytic oxidation of formaldehyde in atmospheric pressure gas streams

    International Nuclear Information System (INIS)

    Formaldehyde (HCHO) is a typical air pollutant capable of causing serious health disorders in human beings. This work reports plasma-catalytic oxidation of formaldehyde in gas streams via dielectric barrier discharges over Ag/CeO2 pellets at atmospheric pressure and 70 0C. With a feed gas mixture of 276 ppm HCHO, 21.0% O2, 1.0% H2O in N2, ∼99% of formaldehyde can be effectively destructed with an 86% oxidative conversion into CO2 at GHSV of 16500 h-1 and input discharge energy density of 108 J l-1. At the same experimental conditions, the conversion percentages of HCHO to CO2 from pure plasma-induced oxidation (discharges over fused silica pellets) and from pure catalytic oxidation over Ag/CeO2 (without discharges) are 6% and 33% only. The above results and the CO plasma-catalytic oxidation experiments imply that the plasma-generated short-lived gas phase radicals, such as O and HO2, play important roles in the catalytic redox circles of Ag/CeO2 to oxidize HCHO and CO to CO2

  14. Session 6: Water depollution from aniline and phenol by air oxidation and adsorptive-catalytic oxidation in liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Dobrynkin, N.M.; Batygina, M.V.; Noskov, A.S. [Boreskov Institute of Catalysis of Siberian Branch of Russian Academy of Sciences, Pr. Ak. Lavrentieva (Russian Federation)

    2004-07-01

    This paper is devoted to development of carbon catalysts and application of catalytic wet air oxidation for deep cleaning of polluted waters. The described catalysts and method are solving the problem of development environmentally reliable method for fluids treatment and allow carrying out the adsorption of pollutants on carbon CAPM (catalytically active porous material) with following regeneration of the CAPM without the loss of adsorptive qualities. The experiments have shown a principal capability simultaneously to use carbon CAPM as adsorbent and either as catalyst, or as a catalyst support for oxidation of aniline and phenol in water solutions. (authors)

  15. Radwaste solidification modifications by means of nitrogen oxides catalytic abatement

    International Nuclear Information System (INIS)

    In the treatment and solidification of medium and high level radioactive wastes, large amounts of NO /sub x/ are produced, which are normally scrubbed with nitric acid or alkaline solutions. In this way big volumes of secondary wastes containing high nitrate concentrations which cannot be easily discharged are produced. The application of the NO /sub x/ catalytic abatement with selective ammonia reduction would permit to avoid this problem, with large cost savings. Two practical examples have been examined: a bituminization plant and a pot vitrification plant referred to the Italian EUREX Reprocessing Pilot Plant. 416,000 and 362,000 $/y respectively would be saved by replacing scrubbing towers with a catalytic reactor

  16. Effect of the plasma-chemical treatment of ZnO and NiO on their activity in the dehydrogenation of isopropanol

    Science.gov (United States)

    Danilova, M. N.; Pylinina, A. I.; Platonov, E. A.; Yagodovskii, V. D.

    2015-08-01

    Treating ZnO and NiO oxides with glow discharge oxygen plasma and high-frequency argon plasma is found to affect the catalytic activity of these oxides in the dehydrogenation reaction of isopropanol, leading to an increase in the conversion of alcohol and the yield of acetone. The increased activity of ZnO is due to the high number of acid sites induced by plasma-chemical treatment. With NiO, the increased activity results from the formation of new, more active sites with low experimental activation energy, rather than a change in the surface acidity.

  17. Hematite concave nanocubes and their superior catalytic activity for low temperature CO oxidation

    Science.gov (United States)

    Liang, Hanfeng; Jiang, Xinde; Qi, Zhengbing; Chen, Wei; Wu, Zhengtao; Xu, Binbin; Wang, Zhoucheng; Mi, Jinxiao; Li, Qingbiao

    2014-06-01

    Hematite (α-Fe2O3) concave nanocubes bound by high-index {134&cmb.macr;4} and {123&cmb.macr;8} facets were synthesized and their catalytic activity for CO oxidation were also investigated.Hematite (α-Fe2O3) concave nanocubes bound by high-index {134&cmb.macr;4} and {123&cmb.macr;8} facets were synthesized and their catalytic activity for CO oxidation were also investigated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00552j

  18. Preparation of Molecular Sieve Catalyst and Application in the Catalytic Oxidation Treatment of Waste Water

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Citric acid is an important additive in foods, cosmetics, medicine and so on, but it discharges about 10 ton of factory effluent when 1 ton of citric acid is produced. The COD of the factory effluent is near 20000 mg/L. The treatment of citric acid factory effluent is a serious problem in environmental chemistry. It is found that molecular sieve support metal complexes have high catalytic activity in aerobic oxidation of alkene [1,2]. In this paper, a kind of molecular sieve catalyst was prepared. The catalyst was used for the treatment of citric acid factory effluent by method of catalytic oxygen oxidation.

  19. Effects of Oxygen Transfer Limitation and Kinetic Control on Biomimetic Catalytic Oxidation of Toluene

    Institute of Scientific and Technical Information of China (English)

    罗伟平; 刘大为; 孙俊; 邓伟; 盛文兵; 刘强; 郭灿城

    2014-01-01

    Under oxygen transfer limitation and kinetic control, liquid-phase catalytic oxidation of toluene over metalloporphyrin was studied. An improved technique of measuring dissolved oxygen levels for gas-liquid reaction at the elevated temperature and pressure was used to take the sequential data in the oxidation of toluene catalyzed by metalloporphyrin. By this technique the corresponding control step of toluene oxidation could be obtained by varying reaction conditions. When the partial pressure of oxygen in the feed is lower than or equal to 0.070 MPa at 463 K, the oxidation of toluene would be controlled by oxygen transfer, otherwise the reaction would be controlled by kinetics. The effects of both oxygen transfer and kinetic control on the toluene conversion and the selectivity of benzaldehyde and benzyl alcohol in biomimetic catalytic oxidation of toluene were systematically investigated. Three conclusions have been made from the experimental results. Firstly, under the oxygen transfer limitation the toluene conversion is lower than that under kinetic control at the same oxidation conditions. Secondly, under the oxygen transfer limitation the total selectivity of benzaldehyde and benzyl alcohol is lower than that under kinetic control with the same conversion of toluene. Finally, under the kinetics control the oxidation rate of toluene is zero-order with respect to oxygen. The experimental results are identical with the biomimetic catalytic mechanism of toluene oxidation over metalloporphyrins.

  20. Surface composition and catalytic activity of La-Fe mixed oxides for methane oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fengxiang [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China); Li, Zhanping [Analysis Center, Tsinghua University, Beijing 100084 (China); Ma, Hongwei [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China); Gao, Zhiming, E-mail: zgao@bit.edu.cn [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China)

    2015-10-01

    Graphical abstract: - Highlights: • The sample with La/Fe atomic ratio of 0.94 is single phase perovskite La{sub 0.94}FeO{sub 3−d}. • The excess ironic oxide exists on the surface of the perovskite crystallites. • La{sup 3+} ions are enriched on surface of the oxides even for the La{sub 0.68}Fe sample. - Abstract: Four La-Fe oxide samples with La/Fe atomic ratio y = 1.02 ∼ 0.68 (denoted as LayFe) were prepared by the citrate method. The samples had a decreased specific surface area with the La/Fe atomic ratio decreasing. XRD pattern proved that the sample La{sub 0.94}Fe is single phase perovskite La{sub 0.94}FeO{sub 3−d}. Phase composition of the samples was estimated by the Rietveld refinement method. XPS analyses indicate that La{sup 3+} ions are enriched on surface of crystallites for all the samples, and surface carbonate ions are relatively abundant on the samples La{sub 1.02}Fe and La{sub 0.94}Fe. Catalytic activity for methane oxidation per unit surface area of the samples is in the order of La{sub 0.68}Fe > La{sub 0.76}Fe > La{sub 0.94}Fe > La{sub 1.02}Fe both in the presence and in the absence of gaseous oxygen. A reason for this order would be the higher concentration of Fe{sup 3+} ion on the surface of the samples La{sub 0.68}Fe and La{sub 0.76}Fe.

  1. Catalytic Oxidation of Methane into Methanol over Copper-Exchanged Zeolites with Oxygen at Low Temperature.

    Science.gov (United States)

    Narsimhan, Karthik; Iyoki, Kenta; Dinh, Kimberly; Román-Leshkov, Yuriy

    2016-06-22

    The direct catalytic conversion of methane to liquid oxygenated compounds, such as methanol or dimethyl ether, at low temperature using molecular oxygen is a grand challenge in C-H activation that has never been met with synthetic, heterogeneous catalysts. We report the first demonstration of direct, catalytic oxidation of methane into methanol with molecular oxygen over copper-exchanged zeolites at low reaction temperatures (483-498 K). Reaction kinetics studies show sustained catalytic activity and high selectivity for a variety of commercially available zeolite topologies under mild conditions (e.g., 483 K and atmospheric pressure). Transient and steady state measurements with isotopically labeled molecules confirm catalytic turnover. The catalytic rates and apparent activation energies are affected by the zeolite topology, with caged-based zeolites (e.g., Cu-SSZ-13) showing the highest rates. Although the reaction rates are low, the discovery of catalytic sites in copper-exchanged zeolites will accelerate the development of strategies to directly oxidize methane into methanol under mild conditions. PMID:27413787

  2. Catalytic Potential of Nano-Magnesium Oxide on Degradation of Humic Acids From Aquatic Solutions

    Directory of Open Access Journals (Sweden)

    Ghorban Asgari

    2014-12-01

    Full Text Available Catalytic ozonation is a new and promising process used to remove the contaminants from drinking water and wastewater. This study aimed to evaluate the catalytic potential of nano-magnesium oxide (nano-MgO for the removal of humic acids (HA from water. Mg (NO32 solution was used to prepare MgO powder by the calcination method. In a semi-batch reactor, the catalytic ozonation was carried out. The effects of the various operating parameters, including pH, reaction time, T-butyl alcohol (TBA and phosphate on HA degradation were evaluated. Experimental results indicated that degradation of HA was increased as the pH solution and reaction time were increased. Maximum HA degradation was obtained at pH = 10 and the reaction time of 10 minutes in the catalytic process. The calculated catalytic potential of nano-MgO on ozonation of HA was 60%. Moreover, catalytic ozonation process was not affected by TBA and the main reaction on HA degradation HA have effect take place on MgO surface. According to the results of this study, the developed MgO catalyst is the active and proficient catalyst in HA degradation using the catalytic ozonation process.

  3. Preparation of hierarchical layer-stacking Mn-Ce composite oxide for catalytic total oxidation of VOCs

    Institute of Scientific and Technical Information of China (English)

    唐文翔; 武晓峰; 刘刚; 李双德; 李东艳; 李文辉; 陈运法

    2015-01-01

    Hierarchical layer-stacking Mn-Ce composite oxide with mesoporous structure was firstly prepared by a simple precipita-tion/decomposition procedure with oxalate precursor and the complete catalytic oxidation of VOCs (benzene, toluene and ethyl ace-tate) were examined. The Mn-Ce oxalate precursor was obtained from metal salt and oxalic acid without any additives. The resulting materials were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), en-ergy dispersive X-ray spectroscopy (EDX), hydrogen temperature programmed reduction (H2-TPR) and X-ray photoelectron spec-troscopy (XPS). Compared with Mn-Ce composite oxide synthesized through a traditional method (Na2CO3 route), the hierarchical layer-stacking Mn-Ce composite oxide exhibited higher catalytic activity in the complete oxidation of volatile organic compounds (VOCs). By means of testing, the data revealed that the hierarchical layer-stacking Mn-Ce composite oxide possessed superior physiochemical properties such as good low-temperature reducibility, high manganese oxidation state and rich adsorbed surface oxy-gen species which resulted in the enhancement of catalytic abilities.

  4. Wet Air Oxidation and Catalytic Wet Air Oxidation for Refinery Spent Caustics Degradation

    International Nuclear Information System (INIS)

    The work focuses on evaluating wet air oxidation and catalytic wet air oxidation technique to degrade refinery spent caustics (original COD is 250,781 mg/L) in a milder operation conditions (150-200 degree C, 0.2-2.5MPa). The results show that: in non-catalyst WAO, the highest COD degradation conversion could reach about 75% when 200 degree C, 2MPa oxygen and 300rpm were used. At every temperature, the reaction procedures follow pseudo-first order equations and the activation energy is 45.5 kJ/mol. The reactivity of three main contaminants in wastewater is on the order of sulphide > petroleum > volatile phenol. The COD degradation conversion could improve to about 95% when composite catalyst MnOx-CeO/sub x//sub x/ gamma-Al/sub 2/O/sub 3/ (W/sub Mn//W gamma-/sub Al/sub 2/O/sub 3/ =0.5/ and WCe/W MnOx Al/sub 2/O/sub 3/=0.4) was used. The pseudo-first order equations also could be applied for catalyst system and its activation energy decreases to 27.2 kJ/mol. The catalyst could improve the degradation efficiency of petroleum and volatile phenol. Their conversions could increase to 85% and 74% respectively after catalyst used. (author)

  5. Catalytic oxidation of water and alcohols by a robust iron(iii) complex bearing a cross-bridged cyclam ligand.

    Science.gov (United States)

    Tan, Peng; Kwong, Hoi-Ki; Lau, Tai-Chu

    2015-08-01

    An iron(iii) complex bearing a cross-bridged cyclam ligand (4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane) is an efficient catalyst for the oxidation of both water and alcohols using sodium periodate as the oxidant. In catalytic water oxidation a maximum turnover number (TON) of 1030 is achieved, while in catalytic alcohol oxidation >95% conversions and yields can be obtained. PMID:26126521

  6. CuO-CeO2 binary oxide nanoplates: Synthesis, characterization, and catalytic performance for benzene oxidation

    International Nuclear Information System (INIS)

    This work reports the first synthesis of CuO-CeO2 binary oxides with a plate-like morphology by a solvothermal method. The as-prepared CuO-CeO2 nanoplates calcined at 400 oC were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrum, and tested for catalytic oxidation of dilute benzene in air. Various structural characterizations showed that large amounts of copper species were exposed on the CuO-CeO2 nanoplate surface. The effect of the synthesis conditions on the structure of the product, as well as the growth process of the nanoplates, has been studied and discussed. The CuO-CeO2 nanoplates exhibited an excellent catalytic activity for benzene oxidation despite its relatively low surface area and could catalyze the complete oxidation of benzene at a temperature as low as 240 oC.

  7. SPONTANEOUS CATALYTIC WET AIR OXIDATION DURING PRE-TREATMENT OF HIGH-LEVEL RADIOACTIVE WASTE SLUDGE

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D.; Herman, C.; Pareizs, J.; Bannochie, C.; Best, D.; Bibler, N.; Fellinger, T.

    2009-10-01

    Savannah River Remediation, LLC (SRR) operates the Defense Waste Processing Facility for the U.S. Department of Energy at the Savannah River Site. This facility immobilizes high-level radioactive waste through vitrification following chemical pretreatment. Catalytic destruction of formate and oxalate ions to carbon dioxide has been observed during qualification testing of non-radioactive analog systems. Carbon dioxide production greatly exceeded hydrogen production, indicating the occurrence of a process other than the catalytic decomposition of formic acid. Statistical modeling was used to relate the new reaction chemistry to partial catalytic wet air oxidation of both formate and oxalate ions driven by the low concentrations of palladium, rhodium, and/or ruthenium in the waste. Variations in process conditions led to increases or decreases in the total oxidative destruction, as well as partially shifting the preferred species undergoing destruction from oxalate ion to formate ion.

  8. Electro-catalytic oxidation device for removing carbon from a fuel reformate

    Science.gov (United States)

    Liu, Di-Jia

    2010-02-23

    An electro-catalytic oxidation device (ECOD) for the removal of contaminates, preferably carbonaceous materials, from an influent comprising an ECOD anode, an ECOD cathode, and an ECOD electrolyte. The ECOD anode is at a temperature whereby the contaminate collects on the surface of the ECOD anode as a buildup. The ECOD anode is electrically connected to the ECOD cathode, which consumes the buildup producing electricity and carbon dioxide. The ECOD anode is porous and chemically active to the electro-catalytic oxidation of the contaminate. The ECOD cathode is exposed to oxygen, and made of a material which promotes the electro-chemical reduction of oxygen to oxidized ions. The ECOD electrolyte is non-permeable to gas, electrically insulating and a conductor to oxidized. The ECOD anode is connected to the fuel reformer and the fuel cell. The ECOD electrolyte is between and in ionic contact with the ECOD anode and the ECOD cathode.

  9. Electro-catalytic oxidation of ethanol on platinum-iridium mixtures supported on glassy carbon

    International Nuclear Information System (INIS)

    Electro-catalytic oxidation of ethanol on platinum-iridium mixtures supported on glassy carbon was studied, in acid media at different temperatures and concentrations. During the maturation time of deposited iridium, the surface is covered by an irreversible oxide formation, which affects the behavior of the catalytic mixture. The Pt70 Ir30 and Pt90 Ir10 mixtures seem to be a little more active than the Pt/C electrode at potentials below 800 mV (vs. HRE). In all electrodes appears two reactions: partial ethanol oxidation to produce acetaldehyde (main path of reaction at low temperatures and high electrode coverage with ethanol adsorption residues) and the total oxidation to carbon dioxide which is considerable at potential above 800 mV and it is increased with increasing temperature

  10. Porous manganese oxide synthesized through organic-electrolyte templates and their catalytic applications

    International Nuclear Information System (INIS)

    We report a facile approach to the preparation of porous manganese oxide materials by the organic-electrolyte templates based on strategy. The final products are thoroughly characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and Brunauer-Emmett-Teller (BET) techniques. The results reveal that porosity (pore size and distribution, surface area) of these manganese oxides has strong relationship with the templates used, which implies a simple way to obtain a series of porous materials. By comparing the catalytic effects of these manganese oxides in oxidation of indene and benzyl alcohol, we find that the pore size and distribution are also crucial to the catalytic properties of these porous materials.

  11. Rhodium-technetium catalysts in dehydrogenation of cyclohexane

    International Nuclear Information System (INIS)

    Catalytic properties of Rh-Tc/support (γ-Al2O3, SiO2 or MgO) system in dehydrogenation of cyclohexane were studied. A nonadditive increase in catalytic activity of bimetallic catalysts in comparison with monometallic catalysts has been established. Diffuse reflectance spectra have shown the presence of ionic forms of the metals in bimetallic catalysts. From the comparison of catalytic and optical properties a conclusion was drawn about the nature of synergism observed, which was accounted for by the formation of RhxTcy clusters. 6 refs.; 5 figs.; 1 tab

  12. Importance of the oxygen bond strength for catalytic activity in soot oxidation

    DEFF Research Database (Denmark)

    Christensen, Jakob M.; Grunwaldt, Jan-Dierk; Jensen, Anker D.

    2016-01-01

    (loose contact) the rate constants for a number of catalytic materials outline a volcano curve when plotted against their heats of oxygen chemisorption. However, the optima of the volcanoes correspond to different heats of chemisorption for the two contact situations. In both cases the activation...... oxidation. The optimum of the volcano curve in loose contact is estimated to occur between the bond strengths of α-Fe2O3 and α-Cr2O3. Guided by an interpolation principle FeaCrbOx binary oxides were tested, and the activity of these oxides was observed to pass through an optimum for an FeCr2Ox binary oxide...

  13. Catalytic oxidation of cyanides in an aqueous phase over individual and manganese-modified cobalt oxide systems

    International Nuclear Information System (INIS)

    The possibility for purification of wastewaters containing free cyanides by applying of a new method based on cyanides catalytic oxidation with air to CO2 and N2 at low temperature and atmospheric pressure was investigated. On this purpose, individual and modified with manganese Co-oxide systems as active phase of environmental catalysts were synthesized. The applied method of synthesis favours the preparation of oxide catalytic systems with high active oxygen content (total-O* and surface-O*s) possessing high mobility, and the metal ions being in a high oxidation state and in an octahedral coordination-factors determining high activity in reactions of complete oxidation. The catalysts employed were characterized by powder X-ray diffraction, Infrared spectroscopy, and chemical analysis. The effect of pH of the medium and catalyst loading on the effectiveness of the cyanide oxidation process, expressed by the degree of conversion (α, %), by the rate constant (k, min-1), and COD was studied. The results obtained reveal that using catalysts investigated a high cyanide removal efficiency could be achieved even in strong alkaline medium. The higher activity of the manganese promoted catalytic sample could be explained on the basis of higher total active oxygen content and its higher mobility both depending on the conditions, under which the synthesis of catalyst is being carried out.

  14. Transition-metal nitro-nitrosyl redox couple: catalytic oxidation of olefins to ketones

    International Nuclear Information System (INIS)

    A new nitroso-nitrosyl redox couple based on the readily prepared complex bis(acetonitrile)chloronitropalladium(II) is reported which catalytically air oxidizes olefines to ketones. Results of 18O labelling mechanistic studies are included, and spectroscopic evidence for an intermediate involved in oxygen-atom transfer by a nitro group is presented. The effects of olefin substituents were also investigated

  15. Catalytic Oxidation of Low Concentration Gaseous Organic Pollutants over Electrospun Nanofibrous Catalysts

    Czech Academy of Sciences Publication Activity Database

    Soukup, Karel; Topka, Pavel; Hejtmánek, Vladimír; Šolcová, Olga

    San Francisco : -, 2014, 40 /P062/. ISBN N. [International Conference on Electrospinning /3./. San Francisco (US), 04.08.2014-07.08.2014] R&D Projects: GA ČR(CZ) GAP204/11/1206 Institutional support: RVO:67985858 Keywords : electrospinning * electrospun nanofibrous catalyst * catalytic oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  16. Catalytic Oxidation of Low Concentration Gaseous Organic Pollutants over Electrospun Nanofibrous Catalysts

    Czech Academy of Sciences Publication Activity Database

    Soukup, Karel; Topka, Pavel; Hejtmánek, Vladimír; Šolcová, Olga

    San Francisco: -, 2014, 40 /P062/. ISBN N. [International Conference on Electrospinning /3./. San Francisco (US), 04.08.2014-07.08.2014] R&D Projects: GA ČR(CZ) GAP204/11/1206 Institutional support: RVO:67985858 Keywords : electrospinning * electrospun nanofibrous catalyst * catalytic oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  17. Pt and Au Nanostructured Materials for Catalytic Oxidation of Ethanol and Toluene

    Czech Academy of Sciences Publication Activity Database

    Gaálová, Jana; Kaluža, Luděk; Topka, Pavel

    2010, s. 409. ISBN N. [NANOSMAT-5. Remis (FR), 19.10.2010-21.10.2010] R&D Projects: GA ČR GPP106/10/P019 Institutional research plan: CEZ:AV0Z40720504 Keywords : catalytic oxidation * ethanol * toluene Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.nanosmat-conference.com/

  18. Orange II removal by catalytic wet peroxide oxidation using activated carbon xerogels

    OpenAIRE

    Pinho, Maria; Silva, Adrián; Fathy, Nady; Attia, Amina; Gomes, Helder; Faria, Joaquim

    2013-01-01

    Orange II is a synthetic dye widely employed in the textile industry and responsible for serious environrnentaI cancerns. Dyes like this urge the development af new technologies for the treatment af wastewaters generated in this industrial activity. Those include catalytic wet peroxide oxidation (CWPO), which is an advanced oxidation process (AOP) based on the generation of hydroxyl radicais (I-lO·) from hydrogen peroxide with tlle aid ofa suitable catalysl [I].

  19. Bulk Preparation of Holey Graphene via Controlled Catalytic Oxidation

    Science.gov (United States)

    Watson, Kent (Inventor); Lin, Yi (Inventor); Ghose, Sayata (Inventor); Connell, John (Inventor)

    2015-01-01

    A scalable method allows preparation of bulk quantities of holey carbon allotropes with holes ranging from a few to over 100 nm in diameter. Carbon oxidation catalyst nanoparticles are first deposited onto a carbon allotrope surface in a facile, controllable, and solvent-free process. The catalyst-loaded carbons are then subjected to thermal treatment in air. The carbons in contact with the carbon oxidation catalyst nanoparticles are selectively oxidized into gaseous byproducts such as CO or CO.sub.2, leaving the surface with holes. The catalyst is then removed via refluxing in diluted nitric acid to obtain the final holey carbon allotropes. The average size of the holes correlates strongly with the size of the catalyst nanoparticles and is controlled by adjusting the catalyst precursor concentration. The temperature and time of the air oxidation step, and the catalyst removal treatment conditions, strongly affect the morphology of the holes.

  20. The applicability of the catalytic wet-oxidation to CELSS

    Science.gov (United States)

    Takahashi, Y.; Nitta, K.; Ohya, H.; Oguchi, M.

    1987-01-01

    The wet oxidation catalysis of Au, Pd, Pt, Rh or Ru on a ceramic honeycomb carrier was traced in detail by 16 to 20 repetitive batch tests each. As a result, Pt or Pd on a honeycomb carrier was shown to catalyze complete nitrogen gasification as N2. Though the catalysts which realize both complete nitrogen gasification and complete oxidation could not be found, the Ru+Rh catalyst was found to be most promising. Ru honeycomb catalyzed both nitrification and nitrogen gasification.

  1. Pt-Sn/SBA-15催化剂的制备、表征和长链烷烃脱氢催化性能%Preparation and Characterization of Pt-Sn/SBA-15 Catalysts and Their Catalytic Performances for Long Chain Alkane Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    卢泽湘; 季生福; 刘辉; 李成岳

    2008-01-01

    A series of the Pt-Sn/SBA-15 catalysts were prepared and their properties characterized by using X-ray powder diffraction(XRD),N2 adsorption-desorption,high resolution transmission electron m~croscope,X-ray pho- toelectron spectroscopy(XPS)and H2-temperature programmed reduction.Their performances in long chain alkane dehydrogen-atiOn were evaluated in a fixed-bed microreactor with dodecane as a model alkane.The results indicated that SBA-15 maintained the well-order mesoporous structure during the reaction.The performance of the catalyst was found not dominated by its textural properties.but by the molar ratio of Sn to Pt which governed the degree of Sn reduction.Owing to the highest degree of Sn reduction,1%(by mass)Pt-1.8%(by mass)Sn/sBA-15 showed the best catalytic activity.At 0.1 Mpa and 470℃,the molar ratio of hydrogen to alkane at 4,and liquid hourly space velocity(LHSV)20 h-1,the dodecane conversion iS 10%,and the dodecene selectivity iS about 70%.

  2. Catalytic performance of heteroatom-modified carbon nanotubes in advanced oxidation processes

    Institute of Scientific and Technical Information of China (English)

    João Restivo; Raquel P. Rocha; Adrián M. T. Silva; José J. M. Órfão; Manuel F. R. Pereira; José L. Figueiredo

    2014-01-01

    Multi-walled carbon nanotubes (CNTs) were submitted to chemical and thermal treatments in or-der to incorporate different heteroatoms on the surface. O-, S-and N-containing groups were suc-cessfully introduced onto the CNTs without significant changes of the textural properties. The cata-lytic activity of these heteroatom-modified CNTs was studied in two liquid phase oxidation pro-cesses:catalytic ozonation and catalytic wet air oxidation (CWAO), using oxalic acid and phenol as model compounds. In both cases, the presence of strongly acidic O-containing groups was found to decrease the catalytic activity of the CNTs. On the other hand, the introduction of S species (mainly sulfonic acids) enhanced the removal rate of the model compounds, particularly in the CWAO of phenol. Additional experiments were performed with a radical scavenger and sodium persulfate, in order to clarify the reaction mechanism. Nitrogen functionalities improve the catalytic performance of the original CNTs, regardless of the process or of the pollutant.

  3. Analysis of heterogeneous oxygen exchange and fuel oxidation on the catalytic surface of perovskite membranes

    KAUST Repository

    Hong, Jongsup

    2013-10-01

    The catalytic kinetics of oxygen surface exchange and fuel oxidation for a perovskite membrane is investigated in terms of the thermodynamic state in the immediate vicinity of or on the membrane surface. Perovskite membranes have been shown to exhibit both oxygen perm-selectivity and catalytic activity for hydrocarbon conversion. A fundamental description of their catalytic surface reactions is needed. In this study, we infer the kinetic parameters for heterogeneous oxygen surface exchange and catalytic fuel conversion reactions, based on permeation rate measurements and a spatially resolved physical model that incorporates detailed chemical kinetics and transport in the gas-phase. The conservation equations for surface and bulk species are coupled with those of the gas-phase species through the species production rates from surface reactions. It is shown that oxygen surface exchange is limited by dissociative/associative adsorption/desorption of oxygen molecules onto/from the membrane surface. On the sweep side, while the catalytic conversion of methane to methyl radical governs the overall surface reactions at high temperature, carbon monoxide oxidation on the membrane surface is dominant at low temperature. Given the sweep side conditions considered in ITM reactor experiments, gas-phase reactions also play an important role, indicating the significance of investigating both homogeneous and heterogeneous chemistry and their coupling when examining the results. We show that the local thermodynamic state at the membrane surface should be considered when constructing and examining models of oxygen permeation and heterogeneous chemistry. © 2013 Elsevier B.V.

  4. A consistent reaction scheme for the selective catalytic reduction of nitrogen oxides with ammonia

    DEFF Research Database (Denmark)

    Janssens, Ton V.W.; Falsig, Hanne; Lundegaard, Lars Fahl;

    2015-01-01

    For the first time, the standard and fast selective catalytic reduction of NO by NH3 are described in a complete catalytic cycle, that is able to produce the correct stoichiometry, while only allowing adsorption and desorption of stable molecules. The standard SCR reaction is a coupling of the ac......For the first time, the standard and fast selective catalytic reduction of NO by NH3 are described in a complete catalytic cycle, that is able to produce the correct stoichiometry, while only allowing adsorption and desorption of stable molecules. The standard SCR reaction is a coupling...... of the activation of NO by O2 with the fast SCR reaction, enabled by the release of NO2. According to the scheme, the SCR reaction can be divided in an oxidation of the catalyst by NO + O2 and a reduction by NO + NH3; these steps together constitute a complete catalytic cycle. Furthermore both NO and NH3...... spectroscopy (FTIR). A consequence of the reaction scheme is that all intermediates in fast SCR are also part of the standard SCR cycle. The calculated activation energy by density functional theory (DFT) indicates that the oxidation of an NO molecule by O2 to a bidentate nitrate ligand is rate determining...

  5. How surface reparation prevents catalytic oxidation of carbon monoxide on atomic gold at defective magnesium oxide surfaces.

    Science.gov (United States)

    Töpfer, Kai; Tremblay, Jean Christophe

    2016-07-21

    In this contribution, we study using first principles the co-adsorption and catalytic behaviors of CO and O2 on a single gold atom deposited at defective magnesium oxide surfaces. Using cluster models and point charge embedding within a density functional theory framework, we simulate the CO oxidation reaction for Au1 on differently charged oxygen vacancies of MgO(001) to rationalize its experimentally observed lack of catalytic activity. Our results show that: (1) co-adsorption is weakly supported at F(0) and F(2+) defects but not at F(1+) sites, (2) electron redistribution from the F(0) vacancy via the Au1 cluster to the adsorbed molecular oxygen weakens the O2 bond, as required for a sustainable catalytic cycle, (3) a metastable carbonate intermediate can form on defects of the F(0) type, (4) only a small activation barrier exists for the highly favorable dissociation of CO2 from F(0), and (5) the moderate adsorption energy of the gold atom on the F(0) defect cannot prevent insertion of molecular oxygen inside the defect. Due to the lack of protection of the color centers, the surface becomes invariably repaired by the surrounding oxygen and the catalytic cycle is irreversibly broken in the first oxidation step. PMID:27345190

  6. On the catalytic gas phase oxidation of butadiene to furan

    Energy Technology Data Exchange (ETDEWEB)

    Kubias, B.; Rodemerck, U. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany); Ritschl, F.; Meisel, M. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Chemie

    1998-12-31

    Applying the thermochemical selectivity criterion of Hadnett et al. It is shown that the selectivity of the furan formation is not limited by a too low strength of the C-H bonds in furan when compared with the C-H bond dissociation energy in the educt molecule butadiene. In the oxidation of butadiene on a CsH{sub 2}PMo{sub 12}O{sub 40} catalyst a maximum yield of 22 mol% furan has been obtained. To improve this comparatively low furan yield oxidation activity of the catalyst must be lowered to prevent the consecutive reaction to maleic anhydride. (orig.)

  7. Study of nano-structured ceria for catalytic CO oxidation

    Czech Academy of Sciences Publication Activity Database

    Valechha, D.; Lokhande, S.; Klementová, Mariana; Šubrt, Jan; Rayalu, S.; Labhsetwar, N.

    2011-01-01

    Roč. 21, č. 11 (2011), s. 3718-3725. ISSN 0959-9428 Institutional research plan: CEZ:AV0Z40320502 Keywords : mesoporous CeO2 * titania * alumina * oxides Subject RIV: CA - Inorganic Chemistry Impact factor: 5.968, year: 2011

  8. A PROCESS FOR THE CATALYTIC OXIDATION OF HYDROCARBONS

    DEFF Research Database (Denmark)

    1999-01-01

    A process for producing an alcohol from a gaseous hydrocarbon, e.g. a lower alkane such as methane, via oxidative reaction of the hydrocarbon in a concentrated sulfuric acid medium in the presence of a catalyst employs an added catalyst comprising a substance selected from iodine, iodine compounds...

  9. Tritiated water processing using liquid phase catalytic exchange and solid oxide electrolyte cell

    International Nuclear Information System (INIS)

    Liquid phase catalytic exchange (LPCE) is an effective method for enrichment and removal of tritium from tritiated water. Combined electrolysis catalytic exchange (CECE) process is an attractive application of a LPCE column. We proposed a new process that improves the CECE process. Using a solid oxide electrolyte (SOE) cell for electrolysis makes the CECE process more energy efficient and eliminates other disadvantages such as large tritium inventory and extremely slow system response. When the cell is used for recombination, the system becomes even more simple, efficiently, reliable and safe. 21 refs., 9 figs

  10. Modeling of adsorber/desorber/catalytic reactor system for ethylene oxide removal

    OpenAIRE

    ZELJKO B. GRBAVCIC; BOSKO V. GRBIC; ZORANA LJ. ARSENIJEVIC

    2004-01-01

    The removal of ethylene oxide (EtO) in a combined system adsorber/desorber/catalytic reactor has been investigated. The combined system was a modified draft tube spouted bed reactor loaded with Pt/Al2O3 catalyst. The annular region was divided into two sectons, the hot section contained about 7 % of catalyst and it behaved as a desorber and catalytic incinerator, while the cold section, with the rest of the catalyst, behaved as a sorber. The catalyst particles were circulated between the two ...

  11. Recombinant oxalate decarboxylase: enhancement of a hybrid catalytic cascade for the complete electro-oxidation of glycerol.

    Science.gov (United States)

    Abdellaoui, Sofiene; Hickey, David P; Stephens, Andrew R; Minteer, Shelley D

    2015-10-01

    The complete electro-oxidation of glycerol to CO2 is performed through an oxidation cascade using a hybrid catalytic system combining a recombinant enzyme, oxalate decarboxylase from Bacillus subtilis, and an organic oxidation catalyst, 4-amino-TEMPO. This system is capable of electrochemically oxidizing glycerol at a carbon electrode collecting all 14 electrons per molecule. PMID:26271633

  12. Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Chang, Jie; Ouyang, Yong; Zheng, Xianwei [South China Univ. of Technology, Guangzhou (China)

    2014-06-15

    High value-added aromatic aldehydes (e. g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide (H{sub 2}O{sub 2}) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin (Co(TPPS{sub 4})) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without Co(TPPS{sub 4}). Moreover, a possible mechanism of HFBO oxidation using Co(TPPS{sub 4})/H{sub 2}O{sub 2} was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under Co(TPPS{sub 4})/H{sub 2}O{sub 2} system.

  13. COAL CONVERSION WASTEWATER TREATMENT BY CATALYTIC OXIDATION IN SUPERCRITICAL WATER; FINAL

    International Nuclear Information System (INIS)

    Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or re-used. Catalytic oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of phenol over different heterogeneous oxidation catalysts in supercritical water. More specifically, we examined the oxidation of phenol over a commercial catalyst and over bulk MnO(sub 2), bulk TiO(sub 2), and CuO supported on Al(sub 2) O(sub 3). We used phenol as the model pollutant because it is ubiquitous in coal-conversion wastewaters and there is a large database for non-catalytic supercritical water oxidation (SCWO) with which we can contrast results from catalytic SCWO. The overall objective of this research project is to obtain the reaction engineering information required to evaluate the utility of catalytic supercritical water oxidation for treating wastes arising from coal conversion processes. All four materials were active for catalytic supercritical water oxidation. Indeed, all four materials produced phenol conversions and CO(sub 2) yields in excess of those obtained from purely homogeneous, uncatalyzed oxidation reactions. The commercial catalyst was so active that we could not reliably measure reaction rates that were not limited by pore diffusion. Therefore, we performed experiments with bulk transition metal oxides. The bulk MnO(sub 2) and TiO(sub 2) catalysts enhance both the phenol disappearance and CO(sub 2) formation rates during SCWO. MnO(sub 2) does not affect the selectivity to CO(sub 2), or to the phenol dimers at a given phenol conversion. However, the selectivities to CO(sub 2) are increased and the selectivities to phenol dimers are decreased in the presence of TiO(sub 2) , which are desirable trends for a catalytic SCWO process. The role of the catalyst appears to be accelerating the rate of formation of

  14. Electro-catalytic oxidative cleavage of lignin in a protic ionic liquid.

    Science.gov (United States)

    Reichert, Elena; Wintringer, Reiner; Volmer, Dietrich A; Hempelmann, Rolf

    2012-04-21

    Lignin is a component of lignocellulosic biomass and a promising matrix for recovering important renewable aromatic compounds. We present a new approach of electro-oxidative cleavage of lignin, dissolved in a special protic ionic liquid, using an anode with particular electro-catalytic activity. As appropriate ionic liquid triethylammonium methanesulfonate was identified, synthesised, explored for dissolution of alkali-lignin and used for electrolysis of 5 wt.% lignin solutions. As appropriate anode material, oxidation-stable ruthenium-vanadium-titanium mixed oxide electrodes were prepared and explored for their electro-catalytic activity. The electrolysis was performed at several potentials in the range from 1.0 V to 1.5 V (vs. an Ag pseudo reference electrode). A wide range of aromatic fragments was identified as cleavage products by means of GC-MS and HPLC measurements. PMID:22398694

  15. Catalytic oxidation of cyclohexane to cyclohexanone and cyclohexanol by tert-butyl hydroperoxide over Pt/oxide catalysts

    Indian Academy of Sciences (India)

    I Rekkab-Hammoumraoui; A Choukchou-Braham; L Pirault-Roy; C Kappenstein

    2011-08-01

    Heterogeneous oxidation of cyclohexane with tertiobutyl hydroperoxide was carried out on Pt/oxide (Al2O3, TiO2 and ZrO2) catalysts in the presence of different solvents (acetic acid and acetonitrile). The catalysts were prepared using Pt(NH3)2(NO2)2 as a precursor and characterized by chemical analysis using the ICP–AES method, XRD, TEM, FTIR and BET surface area determination. The oxidation reaction was carried out at 70°C under atmospheric pressure. The results showed the catalytic performance of Pt/Al2O3 as being very high in terms of turnover frequency.

  16. Catalytic hydrocarbon reactions over supported metal oxides. Final report, August 1, 1986--July 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-10-20

    Oxide catalysis plays a central role in hydrocarbon processing and improvements in catalytic activity or selectivity are of great technological importance because these improvements will translate directly into more efficient utilization of hydrocarbon supplies and lower energy consumption in separation processes. An understanding of the relationships between surface structure and catalytic properties is needed to describe and improve oxide catalysts. The approach has been to prepare supported oxides that have a specific structure and oxidation state and then employ these structures in reaction studies. The current research program is focused on studying the fundamental relationships between structure and reactivity for two important reactions that are present in many oxide-catalyzed processes, partial oxidation and carbon-carbon bond formation. During the course of these studies the author has: (1) developed methods to form and stabilize various Mo and W oxide structures on silica; (2) studied C-H abstraction reactions over the fully oxidized cations; (3) studied C-C bond coupling by metathesis and reductive coupling of aldehydes and ketones over reduced cation structures; and (4) initiated a study of hydrogenation and hydrogenolysis over reduced cation structures.

  17. Synthesis, characterization and catalytic activity toward methanol oxidation of electrocatalyst Pt4+-NH2-MCM-41

    International Nuclear Information System (INIS)

    Highlights: ► It was first confirmed that the Pt4+ exhibited a good electro-catalytic property for methanol oxidation. ► The Pt4+ perfectly distributed on a mesoporous molecular sieve matrix synthesis by a facile method. ► The good performance of catalyst resistance to poisoning because of a homogeneous distribution of Pt4+ and large specific surface area. - Abstract: Mesoporous material with functional group (Pt4+-NH2-MCM-41) was prepared by grafting aminopropyl group and adsorbing platinum ions on the surface of the commercial molecular sieve (MCM-41). The characterization carried out by X-ray photoelectron spectroscopy, X-ray diffraction, and N2 adsorption–desorption measurement pointed out that Pt was adsorbed on the NH2-MCM-41 surface as the oxidation state (Pt4+) and the surface area of Pt4+-NH2-MCM-41 was up to 564 m2/g. Transmission electron microscopy and elemental mapping indicated a homogeneous distribution of Pt4+ throughout all surface of the mesoporous materials. Electro-catalytic properties of methanol oxidation on the Pt4+-NH2-MCM-41 electrode were investigated with electrochemical methods. The results showed that the Pt4+-NH2-MCM-41 electrode exhibited catalytic activity in the methanol electro-oxidation with the apparent activation energy being 49.29 kJ/mol, and the control step of methanol electro-oxidation was the mass transfer process. It is first proved that platinum ions had good electro-catalytic property for methanol oxidation and provided a new idea for developing electrode materials in future.

  18. Physicochemical and catalytic properties of vanadium molybdenum oxide catalyst prepared from vanadyl oxalate

    International Nuclear Information System (INIS)

    The formation of the phase composition, porous structure and catalytic properties of vanadium molybdenum oxide catalyst prepared by sputtered drying of the ammonium paramolybdate and banadyl oxalate with subsequent thermal treatment in the air flow is considered. Comparative study of catalyst properties depending on chemical nature of the initial vanadium compound-vanadyl oxalate and ammonium metavanadate is carried out. It is shown that VMo3O11 compound formation at air flow thermal treatment in a rather broad temperature range (300-400 deg) makes preferable using vanadyl oxalate as compared with ammonium metavanadate for the synthesis of massive vanadium molybdenum oxide catalysts of partial acrolein oxidation to acrylic acid

  19. An Overview of Recent Advances of the Catalytic Selective Oxidation of Ethane to Oxygenates

    Directory of Open Access Journals (Sweden)

    Robert D. Armstrong

    2016-05-01

    Full Text Available The selective partial oxidation of short chain alkanes is a key challenge within catalysis research. Direct ethane oxidation to oxygenates is a difficult aim, but potentially rewarding, and it could lead to a paradigm shift in the supply chain of several bulk chemicals. Unfortunately, low C–H bond reactivity and kinetically labile products are just some reasons affecting the development and commercialisation of such processes. Research into direct ethane oxidation is therefore disparate, with approaches ranging from oxidation in the gas phase at high temperatures to enzyme catalysed hydroxylation under ambient conditions. Furthermore, in overcoming the barrier posed by the chemically inert C–H bond a range of oxidants have been utilised. Despite years of research, this remains an intriguing topic from both academic and commercial perspectives. Herein we describe some recent developments within the field of catalytic ethane oxidation focusing on the formation of oxygenated products, whilst addressing the key challenges which are still to be overcome.

  20. Highly Chemical and Regio-selective Catalytic Oxidation with a Novel Manganese Catalyst

    Institute of Scientific and Technical Information of China (English)

    刘斌; 陈怡; 余成志; 沈征武

    2003-01-01

    The chemical selectivity of a novel active manganese compound [Mn2IVμ-O)3(TMTACN)2] (PF6)2 (1) in catalytic oxidation reactions depended on the structure of substrates and 1 was able to catalyze the oxidation of toluene into benzaldehyde and/or benzoic acid under very mild conditions. The following results were obtained: (1) The selectivity of the oxidation depended on the electronic density of double bonds. Reactivity was absent when strong electron-witherawing groups were conjugated with double bonds. (2) Allylic oxidation reactions mostly take place when double bond is present inside a ring system, whilst epoxiclarion reactions occur when the alkene moiety is part of linear chain. (3) In ring systems, the methylene group was more likely to be oxidized than the methyl group on ailylic position. As expected, the C--H bonds at the bridgeheads were unreactive.The secondary hydroxyl groups are more easily to be oxidized than the primary hydroxyl groups.

  1. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    was investigated using current-potential-power density curves. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, and Mn3O4) and dopedceria (CeO2, Ce1-xGdxO2-x/2, Ce1-xRExO2-delta (RE = Pr, Sm)), the effectiveness...

  2. The catalytic oxidation of manganese in water treatment clarification processes

    OpenAIRE

    Lloyd, A.

    1982-01-01

    The removal of dissolved manganese in water treatment floc blanket clarifiers has been studied. The removal mechanisms may be broadly classed as adsorption and oxidation. Adsorption of manganese (II) occurs rapidly and is completed in less than five minutes under conditions prevailing in a floe blanket clarifier. The extent of adsorption is determined by pH, iron and manganese concentrations. Manganese adsorption is relatively insensitive to the concentration of other cations and anions prese...

  3. Removal of formaldehyde over Mn(x)Ce(1)-(x)O(2) catalysts: thermal catalytic oxidation versus ozone catalytic oxidation.

    Science.gov (United States)

    Li, Jia Wei; Pan, Kuan Lun; Yu, Sheng Jen; Yan, Shaw Yi; Chang, Moo Been

    2014-12-01

    Mn(x)Ce(1)-(x)O(2) (x: 0.3-0.9) prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde (HCHO). At x=0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of CeO(2) to form a solid solution. The catalytic activity was best at x=0.5, at which the temperature of 100% removal rate is the lowest (270°C). The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5wt.% CuO(x) into Mn(0.5)Ce(0.5)O(2). With ozone catalytic oxidation, HCHO (61 ppm) in gas stream was completely oxidized by adding 506 ppm O₃over Mn(0.5)Ce(0.5)O(2) catalyst with a GHSV (gas hourly space velocity) of 10,000 hr⁻¹ at 25°C. The effect of the molar ratio of O(3) to HCHO was also investigated. As O(3)/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O(3)/HCHO ratio of 8, the mineralization efficiency of HCHO to CO(2) was 86.1%. At 25°C, the p-type oxide semiconductor (Mn(0.5)Ce(0.5)O(2)) exhibited an excellent ozone decomposition efficiency of 99.2%, which significantly exceeded that of n-type oxide semiconductors such as TiO(2), which had a low ozone decomposition efficiency (9.81%). At a GHSV of 10,000 hr⁻¹, [O(3)]/[HCHO]=3 and temperature of 25°C, a high HCHO removal efficiency (≥ 81.2%) was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal. PMID:25499503

  4. Catalytic oxidation of calcium sulfite in solution/aqueous slurry

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-qin; WU Zhong-biao; WANG Da-hui

    2004-01-01

    Forced oxidation of calcium sulfite aqueous slurry is a key step for the calcium-based flue gas desulfurization(FGD) residue. Experiments were conducted in a semi-batch system and a continuous flow system on lab scales. The main reactor in semi-batch system is a 1000 ml volume flask. It has five necks for continuous feeding of gas and a batch of calcium sulfite solution/aqueous slurry. In continuous flow system, the main part is a jacketed Pyrex glass reactor in which gas and solution/aqueous slurry are fed continuously. Calcium sulfite oxidation is a series of complex free-radical reactions. According to experimental results and literature data, the reactions are influenced significantly by manganese as catalyst. At low concentration of manganese and calcium sulfite, the reaction rate is dependent on 1.5 order of sulfite concentration, 0.5 order of manganese concentration, and zero order of oxygen concentration in which the oxidation is controlled by chemical kinetics. With concentrations of calcium sulfite and manganese increasing, the reactions are independent gradually on the constituents in solution but are impacted by oxygen concentration. Manganese can accelerate the free-radical reactions, and then enhances the mass transfer of oxygen from gas to liquid. The critical concentration of calcium sulfite is 0.007 mol/L, manganese is 10-4 mol/L, and oxygen is of 0.2-0.4 atm.

  5. Study of the catalytic activity of mixed non-stoichiometric uranium-thorium oxides in carbon monoxide oxidation

    International Nuclear Information System (INIS)

    The aim of this work has been to study the catalytic properties of non-stoichiometric uranium-thorium oxides having the general formula UxTh1-xO2+y, for the oxidation of carbon monoxide. The preparation of pure, homogeneous, isotropic solids having good structural stability and a surface area as high as possible calls for a strict control of the conditions of preparation of these oxides right from the preparation of 'mother salts': the mixed oxalates UxTh1-x(C2O4)2, 2H2O. A study has been made of their physico-chemical properties (overall and surface chemical constitution, texture, structure, electrical conductivity), as well as of their adsorption properties with respect to gaseous species occurring in the catalytic reaction. This analysis has made it possible to put forward a reaction mechanism based on successive oxidations and reductions of the active surface by the reactants. A study of the reactions kinetics has confirmed the existence of this oxidation-reduction mechanism which only occurs for oxides having a uranium content of above 0.0014. The carbon dioxide produced by the reaction acts as an inhibitor by blocking the sites on which carbon monoxide can be adsorbed. These non-stoichiometric mixed oxides are a particularly clear example of catalysis by oxygen exchange between the solid and the gas phase. (author)

  6. Removal of nitrogen compounds from gasification gas by selective catalytic or non-catalytic oxidation; Typpiyhdisteiden poisto kaasutuskaasusta selektiivisellae katalyyttisellae ja ei-katalyyttisellae hapetuksella

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-01

    In gasification reactive nitrogenous compounds are formed from fuel nitrogen, which may form nitrogen oxides in gas combustion. In fluidized bed gasification the most important nitrogenous compound is ammonia (NH{sub 3}). If ammonia could be decomposed to N{sub 2} already before combustion, the emissions if nitrogen oxides could be reduced significantly. One way of increasing the decomposition rate of NH{sub 3} could be the addition of suitable reactants to the gas, which would react with NH{sub 3} and produce N{sub 2}. The aim of this research is to create basic information, which can be used to develop a new method for removal of nitrogen compounds from gasification gas. The reactions of nitrogen compounds and added reactants are studied in reductive atmosphere in order to find conditions, in which nitrogen compounds can be oxidized selectively to N{sub 2}. The project consists of following subtasks: (1) Selective non-catalytic oxidation (SNCO): Reactions of nitrogen compounds and oxidizers in the gas phase, (2) Selective catalytic oxidation (SCO): Reactions of nitrogen compounds and oxidizers on catalytically active surfaces, (3) Kinetic modelling of experimental results in co-operation with the Combustion Chemistry Research Group of Aabo Akademi University. The most important finding has been that NH{sub 3} can be made to react selectively with the oxidizers even in the presence of large amounts of CO and H{sub 2}. Aluminium oxides were found to be the most effective materials promoting selectivity. (author)

  7. Heterogeneous catalytic oxidation of As(III) on nonferrous metal oxides in the presence of H2O2.

    Science.gov (United States)

    Kim, Dong-hyo; Bokare, Alok D; Koo, Min suk; Choi, Wonyong

    2015-03-17

    The oxidation of As(III) (arsenite) to As(V) (arsenate), a critical pretreatment process for total arsenic removal, is easily achieved using chemical oxidation methods. Hydrogen peroxide (H2O2) is widely used as an environmentally benign oxidant but its practical use for the arsenite oxidation is limited by the strong pH dependence and slow oxidation kinetics. This study demonstrated that H2O2-induced oxidation of As(III) can be markedly enhanced in the presence of nonferrous metal oxides (e.g., WO3, TiO2, ZrO2) as a heterogeneous catalyst working over a wide pH range in ambient reaction conditions. In particular, TiO2 is an ideal catalyst because it is not only active and stable but also easily available and inexpensive. Although the photocatalytic oxidation of As(III) on TiO2 was intensively studied, the thermal catalytic activities of TiO2 and other nonferrous metal oxides for the arsenic oxidation have been little investigated. The heterogeneous oxidation rate increased with increasing the TiO2 surface area and [H2O2] and weakly depended on pH whereas the homogeneous oxidation by H2O2 alone was favored only at alkaline condition. The oxidation rate in the TiO2/H2O2 system was not reduced at all in the absence of dioxygen. It was not retarded at all by OH radical scavengers but markedly inhibited by hydroperoxyl radical scavengers. It is proposed that the surface complexation of H2O2 on TiO2 induces the generation of the surface hydroperoxyl radical through an inner-sphere electron transfer, which subsequently reacts with As(III). The catalytic activity of TiO2 was maintained without showing any sign of deactivation. The heterogeneous catalytic oxidation is proposed as a viable method for the preoxidation treatment of As(III)-contaminated water under ambient conditions. PMID:25695481

  8. Electrochemical study on the cationic promotion of the catalytic SO2 oxidation in pyrosulfate melts

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Cappeln, Frederik Vilhelm

    1998-01-01

    in the catalytic SO, oxidation most likely is the oxidation of V(IV) to V(V) and the Na+ and Cs+ promoting effect is based on the acceleration of this stage. It has also been proposed that voltammetric measurements can be used for fast optimization of the composition of the vanadium catalyst (which...... catalytic oxidation of SO2 in the V2O5-M2S2O7 system and the effect of these alkali cations on the electrochemical behavior of V2O5 in the alkali pyrosulfate melts It has been shown that Na+ ions had a promoting effect on the V(V) reversible arrow V(IV) electrochemical reaction. Sodium ions accelerate both...... the V(V) reduction and the V(IV) oxidation, the effect being more pronounced in the case of the V(IV) oxidation. Sodium ions also had a significant (almost 0.2 V) depolarization effect on the V(IV) --> V(V) oxidation. The peak current of the V(IV) --> V(V) oxidation waves vs. Na2S2O7 concentration...

  9. Catalytic ozonation of oxalate with a cerium supported palladium oxide: An efficient degradation not relying on hydroxyl radical oxidation

    KAUST Repository

    Zhang, Tao

    2011-11-01

    The cerium supported palladium oxide (PdO/CeO 2) at a low palladium loading was found very effective in catalytic ozonation of oxalate, a probe compound that is difficult to be efficiently degraded in water with hydroxyl radical oxidation and one of the major byproducts in ozonation of organic matter. The oxalate was degraded into CO 2 during the catalytic ozonation. The molar ratio of oxalate degraded to ozone consumption increased with increasing catalyst dose and decreasing ozone dosage and pH under the conditions of this study. The maximum molar ratio reached around 1, meaning that the catalyst was highly active and selective for oxalate degradation in water. The catalytic ozonation, which showed relatively stable activity, does not promote hydroxyl radical generation from ozone. Analysis with ATR-FTIR and in situ Raman spectroscopy revealed that 1) oxalate was adsorbed on CeO 2 of the catalyst forming surface complexes, and 2) O 3 was adsorbed on PdO of the catalyst and further decomposed to surface atomic oxygen (*O), surface peroxide (*O 2), and O 2 gas in sequence. The results indicate that the high activity of the catalyst is related to the synergetic function of PdO and CeO 2 in that the surface atomic oxygen readily reacts with the surface cerium-oxalate complex. This kind of catalytic ozonation would be potentially effective for the degradation of polar refractory organic pollutants and hydrophilic natural organic matter. © 2011 American Chemical Society.

  10. Catalytic hydrocarbon reactions over supported metal oxides. Progress report, April 1, 1994--January 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-01-31

    Oxide catalysis plays a central role in hydrocarbon processing and improvements in catalytic activity or selectivity are of great technological importance because these improvements will translate directly into more efficient utilization of hydrocarbon supplies and lower energy consumption in separation processes. An understanding of the relationships between surface structure and catalytic properties is needed to describe and improve oxide catalysts. Our approach has been to prepare supported oxides that have a specific structure and oxidation state and then employ these structures in reaction studies. Our current research program is focused on studying the fundamental relationships between structure and reactivity for two important reactions that are present in many oxide-catalyzed processes, partial oxidation and carbon-carbon bond formation. Oxide catalysis can be a complex process with both metal cation and oxygen anions participating in the chemical reactions. From an energy perspective carbon-carbon bond formation is particularly relevant to CO hydrogenation in isosynthesis. Hydrogenolysis and hydrogenation form the basis for heteroatom removal in fuels processing. Understanding the catalysis of these processes (and others) requires isolating reaction steps in the overall cycle and determining how structure and composition influence the individual reaction steps. Specially designed oxides, such as we use, permit one to study some of the steps in oxidation, carbon-carbon coupling and heteroatom removal catalysis. During the course of our studies we have: (1) developed methods to form and stabilize various Mo and W oxide structures on silica; (2) studied C-H abstraction reactions over the fully oxidized cations; (3) studied C-C bond coupling by methathesis and reductive coupling of aldehydes and ketones over reduced cation structures; and (4) initiated a study of hydrogenation and hydrogenolysis over reduced cation structures.

  11. Microreactor for the Catalytic Partial Oxidation of Methane

    Institute of Scientific and Technical Information of China (English)

    Widodo Wahyu Puwanto; Yuswan Muharam

    2006-01-01

    Fixed-bed reactors for the partial oxidation of methane to produce synthetic gas still pose hotspot problems. An alternative reactor, which is known as the shell-and-tube-typed microreactor, has been developed to resolve these problems. The microreactor consists of a 1 cm outside-diameter, 0.8 cm insidediameter and 11 cm length tube, and a 1.8 cm inside-diameter shell. The tube is made of dense alumina and the shell is made of quartz. Two different methods dip and spray coating were performed to line the tube side with the LaNixOy catalyst. Combustion and reforming reactions take place simultaneously in this reactor. Methane is oxidized in the tube side to produce flue gases (CO2 and H2O) which flow counter-currently and react with the remaining methane in the shell side to yield synthesis gas. The methane conversion using the higher-loading catalyst spray-coated tube reaches 97% at 700 ℃, whereas that using the lower-loading catalyst dip-coated tube reaches only 7.78% because of poor adhesion between the catalyst film and the alumina support. The turnover frequencies (TOFs) using the catalyst spray-and 900 ℃ provides better performance than that at 1250 ℃ because sintering reduces the surface-area. The hydrogen to carbon monoxide ratio produced by the spray-coated catalyst is greater than the stoichiometric ratio, which is caused by carbon deposition through methane cracking or the Boudouard reaction.

  12. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    Hybrid direct carbon fuel cells (HDCFCs) consisting of a solid carbon (carbon black)-molten carbonate ((62-38 wt% Li-K)2CO3) mixtures in the anode chamber of an anode-supported solid oxide fuel cell (SOFC)-type full-cell (NiO-yttria-stablized zirconia (YSZ)|YSZ|lanthanum strontium manganite (LSM...... in the carbon-carbonate mixture in the anode chamber of an HDCFC. 96-4 vol% N2-CO2 (anode), air (cathode), 755°C, 0-600 mA, 50 mA/step. Power density corrected to cathode geometric surface area. [Formula]...... impedance data as a function of temperature, anode and cathode atmospheres, and their flow rates are discussed. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, and Mn3O4, Fig. 1) and doped-ceria (CeO2, Ce1-xGdxO2, Ce...

  13. Pretreatment of apramycin wastewater by catalytic wet air oxidation

    Institute of Scientific and Technical Information of China (English)

    YANG Shao-xia; FENG Yu-jie; WAN Jia-feng; LIN Qing-ying; ZHU Wan-peng; JIANG Zhan-peng

    2005-01-01

    The pretreatment technology of wet air oxidation(WAO) and coagulation and acidic hydrolysis for apramycin wastewater was investigated in this paper. The COD, apramycin, NH4+ concentration, and the ratio of BOD5/COD were analyzed, and the color and odor of the effluent were observed. WAO of apramycin wastewater, without catalyst and with RuO2/Al2 O3 and RuO2-CeO2/Al2 O3 catalysts, was carried out at degradation temperature of 200℃ and the total pressure of 4 MPa in a 1 L batch reactor. The result showed that the apramycin removals were respectively 50.2% and 55.0%, COD removals were 40.0% and 46.0%, and the ratio of BOD5/COD was increased to 0.49 and 0.54 with RuO2/Al2 O3 and RuO2-CeO2/Al2 O3 catalysts in catylytic wet air oxidation(CWAO) after the reaction of 150 min. With the pretreatment of coagulation and acidic hydrolysis, COD and apramycin removals were slight decreased, and the ratio of BOD5/COD was increased to 0.45, and the effluents was not suitable to biological treatment. The color and odor of the wastewater were the apramycin wastewater. The addition of CeO2 could promote the activity and stability of RuO2/Al2 O3 in WAO of apramycin wastewater.

  14. Influence of physicochemical treatments on spent palladium based catalyst for catalytic oxidation of VOCs

    International Nuclear Information System (INIS)

    To recycle the spent catalyst for the removal of VOCs, the benzene, toluene, and xylene (BTX) complete oxidations were studied over pretreated palladium based spent catalyst in a fixed bed flow reactor system at atmospheric pressure. Two different pretreatment methods with gas (air and hydrogen) and acid aqueous solution (HCl, H2SO4, HNO3, H3PO4 and CH3COOH) were used to investigate the catalytic activity of spent catalyst. The properties of the spent and pretreated Pd based catalyst were characterized by XRD, BET, TEM, ICP, and XPS. The results of light-off curves indicate that the catalytic activity of toluene oxidation for pretreated samples is in the order of hydrogen > air > HNO3 > CH3COOH > H2SO4 > H3PO4 > HCl. In addition, the air and the acid aqueous pretreated catalyst activities were significantly decreased compared to that of the spent (or parent) catalyst. Moreover, hydrogen pretreated (or reduced) catalysts having mainly metallic form show the best performance in removing the toluene vapours compared to other pretreated samples. The reduction temperature made a significant difference in the catalytic performance of the spent catalyst pretreated with hydrogen. XPS results clearly supported that the palladium state of the spent catalysts pretreated at 300 deg. C was shifted more toward metallic form than other reduced catalysts. Furthermore, the results of a long-term test and catalytic activity of aromatic hydrocarbons also supported that the hydrogen pretreated spent catalyst was a good candidate for removing toxic compounds

  15. Final Report: Catalytic Hydrocarbon Reactions over Supported Metal Oxides, August 1, 1995 - July 31, 1999

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, John G.

    1999-07-31

    The research program focused on the catalysis of hydrodesulfurization (HDS) over molybdenum-based catalysts and how catalyst composition, redox ability, structure and neighboring sites control the catalytic properties of metal oxides. We sought to understand the catalytic features/sites that control hydrogenation, hydrogenolysis, and isomerization during HDS. Unprompted silica-supported molybdenum oxides and molybdenum sulfides were studied. Model catalyst systems were prepared from organometallic precursors or cluster compounds to generate supported structures that feature Mo(II) and Mo(IV) cations that are isolated or in ensembles and that have either Mo-O or Mo-S bonds. Conventional MOS{sub 2} catalysts, which contain both edge and rim sites, were be studied. Finally, single-layer MOS{sub 2} structures were also prepared from 2H-MoS{sub 2} powder so that the model systems could be compared against a disulfide catalyst that only involves rim sites. Catalytic reactions for thiophene and tetrahydrothione were studied over the various catalysts. Oxidation states were determined using X-ray photoelectron spectroscopy. X-ray crystallography was used to characterize and follow changes in the MOS{sub 2} structures. The program on metal oxides prepared supported oxides that have a specific structure and oxidation state to serve as model templates for the more complex commercial catalysts and then employed these structures in reaction studies. This focus area examined the relationships between structure and cation redox characteristics in oxidation catalysis. Infrared and Raman spectroscopy were used to characterize the cations and reaction intermediates.

  16. Study of the catalytic activity of pure or cerium-containing thoria in the catalytic oxidation of carbon monoxide (1963)

    International Nuclear Information System (INIS)

    We have undertaken research into the oxidation of carbon monoxide on pure thoria prepared by the decomposition of thorium nitrate, and on the same oxide containing small amounts of cerium. The results we have obtained, both as concerns the chemisorption of the various gases as well as the conductivity of the absorbent and the kinetics of the oxidation itself, appear to be quite coherent. The following steps occur: 1) The carbon monoxide is adsorbed on a clean catalyst surface, the oxygen remaining un-adsorbed. 2) The oxygen is adsorbed on a previously adsorbed carbon, monoxide layer, and reacts to give carbon dioxide (no role being played by the lattice oxygen). This behaviour is usual for a p-type semiconductor. We have in fact confirmed that semi-conductivity is of this type, and the gas-solid interactions can be written: (1) CO(g) ↔ CO+(a) + e- (2) CO+ 1/2 O2(g) + 2 e- → CO-2(a) (3) CO-2(a) ↔ CO2(g) + e- The kinetic equation obtained by supposing that step (2) is the slowest, makes it possible to deduce correctly the experimental results which can be expressed as: dp / dt = k (P0.3CO x P0.5O2) / (1+ k' x PCO2) The influence of the addition of small amounts of cerium can also be explained logically by this process; there is in fact both a decrease in the conductivity and an increase in the catalytic activity, this being characteristic, according to VOLKENSTEIN [52] of an n-type rate-determining reaction occurring on a p-type semi-conductor. We believe that these first results could be advantageously complemented by a study of thoria prepared by other means and doped differently. (author)

  17. Microwave-enhanced catalytic degradation of 4-chlorophenol over nickel oxides under low temperature

    International Nuclear Information System (INIS)

    Microwave-enhance catalytic degradation (MECD) of 4-chlorophenol (4-CP) using nickel oxide was studied. A mix-valenced nickel oxide was obtained from nickel nitrate aqueous solution through a precipitation with sodium hydroxide and an oxidation by sodium hypochlorite (assigned as PO). Then, the as-prepared PO was irradiated under microwave irradiation to fabricate a high active mix-valenced nickel oxide (assigned as POM). Further, pure nanosized nickel oxide was obtained from the POM by calcination at 300, 400 and 500 deg. C (labeled as C300, C400 and C500, respectively). They were characterized by X-ray (XRD), infrared spectroscopy (IR) and temperature-programmed reduction (TPR). Their catalytic activities towards the degradation of 4-CP on the efficiency of the degradation were further investigated under continuous bubbling of air through the liquid-phase and quantitative evaluation by high pressure liquid chromatography (HPLC). Also, the effects of temperature, pH and kinds of catalysts on the efficiency of the degradation have been investigated. The results showed that the 4-CP was degraded completely by MECD method within 20 min under pH 7, T = 40 deg. C and C = 200 g dm-3 over POM catalyst. The relative activity was affected significantly with the oxidation state of nickel

  18. Catalytic activity of CuOn-La2O3/γ-Al2O3 for microwave assisted ClO2 catalytic oxidation of phenol wastewater

    International Nuclear Information System (INIS)

    In order to develop a catalyst with high activity and stability for microwave assisted ClO2 catalytic oxidation, we prepared CuOn-La2O3/γ-Al2O3 by impregnation-deposition method, and determined its properties using BET, XRF, XPS and chemical analysis techniques. The test results show that, better thermal ability of γ-Al2O3 and high loading of Cu in the catalyst can be achieved by adding La2O3. The microwave assisted ClO2 catalytic oxidation process with CuOn-La2O3/γ-Al2O3 used as catalyst was also investigated, and the results show that the catalyst has an excellent catalytic activity in treating synthetic wastewater containing 100 mg/L phenol, and 91.66% of phenol and 50.35% of total organic carbon (TOC) can be removed under the optimum process conditions. Compared with no catalyst process, CuOn-La2O3/γ-Al2O3 can effectively degrade contaminants in short reaction time and with low oxidant dosage, extensive pH range. The comparison of phenol removal efficiency in the different process indicates that microwave irradiation and catalyst work together to oxidize phenol effectively. It can therefore be concluded from results and discussion that CuOn-La2O3/γ-Al2O3 is a suitable catalyst in microwave assisted ClO2 catalytic oxidation process

  19. Influence of Rare Earth Doping on the Structural and Catalytic Properties of Nanostructured Tin Oxide

    Directory of Open Access Journals (Sweden)

    Maciel Adeilton

    2008-01-01

    Full Text Available AbstractNanoparticles of tin oxide, doped with Ce and Y, were prepared using the polymeric precursor method. The structural variations of the tin oxide nanoparticles were characterized by means of nitrogen physisorption, carbon dioxide chemisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The synthesized samples, undoped and doped with the rare earths, were used to promote the ethanol steam reforming reaction. The SnO2-based nanoparticles were shown to be active catalysts for the ethanol steam reforming. The surface properties, such as surface area, basicity/base strength distribution, and catalytic activity/selectivity, were influenced by the rare earth doping of SnO2and also by the annealing temperatures. Doping led to chemical and micro-structural variations at the surface of the SnO2particles. Changes in the catalytic properties of the samples, such as selectivity toward ethylene, may be ascribed to different dopings and annealing temperatures.

  20. Catalytic oxidation for treatment of ECLSS and PMMS waste streams. [Process Material Management Systems

    Science.gov (United States)

    Akse, James R.; Thompson, John; Scott, Bryan; Jolly, Clifford; Carter, Donald L.

    1992-01-01

    Catalytic oxidation was added to the baseline multifiltration technology for use on the Space Station Freedom in order to convert low-molecular weight organic waste components such as alcohols, aldehydes, ketones, amides, and thiocarbamides to CO2 at low temperature (121 C), thereby reducing the total organic carbon (TOC) to below 500 ppb. The rate of reaction for the catalytic oxidation of aqueous organics to CO2 and water depends primarily upon the catalyst, temperature, and concentration of reactants. This paper describes a kinetic study conducted to determine the impact of each of these parameters upon the reaction rate. The results indicate that a classic kinetic model, the Langmuir-Hinshelwood rate equation for heterogeneous catalysis, can accurately represent the functional dependencies of this rate.

  1. Preparation of Molecular Sieve Catalyst and Application in the Catalytic Oxidation Treatment of Waste Water

    Institute of Scientific and Technical Information of China (English)

    WANG; RongMin

    2001-01-01

    Citric acid is an important additive in foods, cosmetics, medicine and so on, but it discharges about 10 ton of factory effluent when 1 ton of citric acid is produced. The COD of the factory effluent is near 20000 mg/L. The treatment of citric acid factory effluent is a serious problem in environmental chemistry.  It is found that molecular sieve support metal complexes have high catalytic activity in aerobic oxidation of alkene [1,2]. In this paper, a kind of molecular sieve catalyst was prepared. The catalyst was used for the treatment of citric acid factory effluent by method of catalytic oxygen oxidation.  ……

  2. Influence of catalyst pretreatments on the catalytic oxidation of toluene over nanostructured platinum based spent catalyst.

    Science.gov (United States)

    Shim, Wang-Geun; Lee, Jae-Wook; Kim, Sang-Chai

    2007-11-01

    In this study, we regenerated a nano-structured platinum based spent catalyst by applying thermal gas and acid pretreatment and examined the influence of treatment on the catalytic oxidation of toluene. The spent catalysts were pretreated with air, hydrogen and six different acid aqueous solutions (HCl, H2SO4, HNO3, H3PO4, CH3COOH and C2H2O4). The physicochemical properties of the parent and its modified catalysts were characterized by XRD, BET, TEM, and ICP. The results of light-off curves showed that air and hydrogen treated catalysts were more active than the parent catalyst. In addition, the catalytic activities of toluene oxidation for acid aqueous treated samples were identical with the order of Pt/Al ratio. PMID:18047055

  3. Optical and electro-catalytic studies of nanostructured thulium oxide for vitamin C detection

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jay [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Srivastava, Manish [Department of Physics, Dehradun Institute of Technology (DIT), School of Engineering, Greater Noida 201308 (India); Roychoudhury, Appan [Department of Biotechnology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110 042 (India); Lee, Dong Won [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Lee, Seung Hee, E-mail: lsh1@jbnu.ac.kr [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Malhotra, B.D., E-mail: bansi.malhotra@gmail.com [Department of Biotechnology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110 042 (India); Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, Material Physics and Engineering Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110 012 (India); Center for NanoBioengineering and Spintronics, Chungnam National University, 220 Gung-Dong, Yuseong-Gu, Daejeon 305-764 (Korea, Republic of)

    2013-11-25

    Highlights: •Nanostructured thulium oxide has been prepared using the hydrothermal process. •Thulium oxide exhibits excellent electrochemical response towards ascorbic acid. •Thulium oxide is interesting electro-optical material. •Rare earth metal oxide offers potential application biosensing and optoelectronics. -- Abstract: In this report, the nanostructured thulium oxide (Tm{sub 2}O{sub 3}) has been prepared using the hydrothermal process without using any template and further heat treatment. The crystalline structure and morphology of prepared sample have been determined by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopic techniques. The optical properties of prepared sample have been examined by ultra-violet (UV–Vis), photoluminescence (PL), Raman and X-ray photoelectron spectroscopy (XPS) studies. Furthermore, Tm{sub 2}O{sub 3} nanoparticles have been electrophoretically deposited (EPD) onto indium–tin–oxide (ITO) glass substrate and utilized for electro-oxidation of ascorbic acid (AA). The electro-catalytic behavior of Tm{sub 2}O{sub 3}/ITO and bare ITO electrodes for AA electro-oxidation has been studied by cyclic voltammetry. Catalytic oxidation peak current shows a linear dependence on the AA concentration and a linear calibration curve is obtained in the concentration range of 0.2–8 mM of AA. The obtained results indicate that the nanostructured Tm{sub 2}O{sub 3} based electrode offers an efficient strategy and a new promising platform for application of the rare earth metal oxide material in electrochemistry and bioelectronics.

  4. Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Singh, Thishana; Harris, Pernille;

    2015-01-01

    The mechanism for the iridium-BINAP catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of molecular hydrogen and carbon monoxide was studied experimentally and computationally. The reaction takes place by tandem catalysis through two catalytic cycles involving...... dehydrogenation of the alcohol and decarbonylation of the resulting aldehyde. The square planar complex IrCl(CO)(rac-BINAP) was isolated from the reaction between [Ir(cod)Cl](2), rac-BINAP, and benzyl alcohol. The complex was catalytically active and applied in the study of the individual steps in the catalytic...... cycles. One carbon monoxide ligand was shown to remain coordinated to iridium throughout the reaction, and release of carbon monoxide was suggested to occur from a dicarbonyl complex. IrH2Cl(CO)(rac-BINAP) was also synthesized and detected in the dehydrogenation of benzyl alcohol. In the same experiment...

  5. Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Yuting [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Xiong, Ya; Tian, Shuanghong [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275 (China); Kong, Lingjun [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Descorme, Claude, E-mail: claude.descorme@ircelyon.univ-lyon1.fr [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

    2014-07-15

    Highlights: • A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared. • FeSC exhibited high catalytic activity in the wet air oxidation of 2-chlorophenol. • A strong correlation was observed between the 2-CP conversion, the iron leaching and the pH. • Using an acetate buffer, the iron leaching was suppressed while keeping some catalytic activity. • A simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst. - Abstract: A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pH{sub PZC}, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120 °C under 0.9 MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5 h and 90% Total Organic Carbon (TOC) was removed after 24 h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst.

  6. Catalytic production of carbon nanotubes over first row transition metal oxides supported on montmorillonite

    International Nuclear Information System (INIS)

    Clay-carbon nanotube composites were prepared by employing the catalytic chemical vapor deposition method (CCVD) over different transition metal oxides supported on montmorillonite. Various analytical techniques including SEM, TEM, XRD and DTA/TGA were used for the characterization of the final composite materials. The morphology, quality and structure of the produced nanotubes is shown to be dependent on the type of transition metals

  7. Investigation of catalyst and solvent systems for the catalytic oxidation of Kraft lignin

    OpenAIRE

    Mora Mir, Joan

    2010-01-01

    Lignin is one of the main constituents of wood together with cellulose and hemicellulose and can be used as a renewable feedstock for the production of chemicals. Lignin is an amorphous polymer which is separated from cellulose during the pulping processes in the paper industry. The Kraft process is the most extended pulping process and the so called Kraft lignin is one of the most promising sources for the obtaining of value-added products from its degradation. The catalytic oxidation of ...

  8. Visualizing a Catalyst at Work during the Ignition of the Catalytic Partial Oxidation of Methane

    DEFF Research Database (Denmark)

    Kimmerle, Bertram; Grunwaldt, Jan-Dierk; Baiker, Alfons;

    2009-01-01

    We present a spatiotemporal operando X-ray absorption study of a highly dynamic process, the ignition of the noble metal catalyzed partial oxidation of methane. Evolvement and propagation of the platinum component's structural changes are investigated with a high-speed X-ray camera, which in comb...... combination with temperature profiling by IR-thermography and catalytic activity measurements by online mass spectrometry gives insight into the first stages of the ignition of the reaction toward hydrogen and carbon monoxide....

  9. The catalytic oxidation of biomass to new materials focusing on starch, cellulose and lignin

    OpenAIRE

    Collinson, S. R.; Thielemans, W.

    2010-01-01

    Biomass is a renewable class of materials of growing interest amongst researchers aiming to achieve global sustainability. This review focuses on the homogeneous catalysis of the oxidation of biomass, in particular starch, cellulose and lignin. Often such catalytic reactions lead to depolymerisation of the material as happens in Nature with for example brown rot fungi. This depolymerisation can be desirable or not, and control in industrial applications is thus important to obtain the desired...

  10. Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts

    International Nuclear Information System (INIS)

    Highlights: • A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared. • FeSC exhibited high catalytic activity in the wet air oxidation of 2-chlorophenol. • A strong correlation was observed between the 2-CP conversion, the iron leaching and the pH. • Using an acetate buffer, the iron leaching was suppressed while keeping some catalytic activity. • A simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst. - Abstract: A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pHPZC, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120 °C under 0.9 MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5 h and 90% Total Organic Carbon (TOC) was removed after 24 h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst

  11. Carbon nanotubes: a suitable material for catalytic wet peroxide oxidation of organic pollutants?

    OpenAIRE

    Ribeiro, Rui; Silva, Adrián; Faria, Joaquim; Gomes, Helder

    2012-01-01

    Carbon materials, such as activated carbons (AC), graphite and activated carbon xerogels, have been explored as metal-free catalysts for the catalytic wet peroxide oxidation (CWPO) of bio-refractory organic compounds, such as azo dyes and phenolic compounds [1-3]. At the same time, the application of carbon nanomaterials in catalysis, such as carbon nanotubes (CNT), has grown exponentially [4]. In the present work, commercial multiwalled carbon nanotubes (MWNT) were used in the CWPO of 2-nitr...

  12. The influence of carbon material properties on the efficiency of catalytic wet peroxide oxidation processes

    OpenAIRE

    Gomes, Helder; R. Ribeiro; Silva, Adrián; Figueiredo, José; Faria, Joaquim

    2015-01-01

    Carbon materiais are well known catalysts for activatin§ H^O^ into hydroxyl radicais (HO'), which are efficient oxidizin § agents. By making use of highly reactive HO" radicais, the elimination of organic compounds can be accomplished by catalytic wet peroxide oxidation (CWPO), a water treatment technology operating under mild conditions of pressure and temperature that hás gained importance due to the decreasing cost of H;0; and its increasing use in wastewater treatm...

  13. Thermodynamic Study on the Catalytic Partial Oxidation of Methane to Syngas

    Institute of Scientific and Technical Information of China (English)

    XUJian; WEIWeisheng; 等

    2002-01-01

    The catalytic partial oxidation of methane to syngas (CO+H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature,pressure,CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.

  14. Catalytic Decomposition of Nitrous Oxide over Calcined Hydrotalcite-like Compounds

    Czech Academy of Sciences Publication Activity Database

    Obalová, L.; Kovanda, F.; Jirátová, Květa; Chmielová, M.; Wichterle, K.; Dorničák, V.

    Vol. 1. Prague : Process Engineering Publisher, 2002, s. 356. ISBN 80-86059-33-2. [International Congress of Chemical and Process Engineering CHISA 2002 /15./. Prague (CZ), 25.08.2002-29.08.2002] R&D Projects: GA ČR GA106/02/0523 Institutional research plan: CEZ:AV0Z4072921 Keywords : nitrous oxide * catalytic decomposition * hydrotalcite Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  15. Oxidation of hydrogen halides to elemental halogens with catalytic molten salt mixtures

    Science.gov (United States)

    Rohrmann, Charles A.

    1978-01-01

    A process for oxidizing hydrogen halides by means of a catalytically active molten salt is disclosed. The subject hydrogen halide is contacted with a molten salt containing an oxygen compound of vanadium and alkali metal sulfates and pyrosulfates to produce an effluent gas stream rich in the elemental halogen. The reduced vanadium which remains after this contacting is regenerated to the active higher valence state by contacting the spent molten salt with a stream of oxygen-bearing gas.

  16. A New Homogeneous Catalyst for the Dehydrogenation of Dimethylamine Borane Starting with Ruthenium(III Acetylacetonate

    Directory of Open Access Journals (Sweden)

    Ebru Ünel Barın

    2015-06-01

    Full Text Available The catalytic activity of ruthenium(III acetylacetonate was investigated for the first time in the dehydrogenation of dimethylamine borane. During catalytic reaction, a new ruthenium(II species is formed in situ from the reduction of ruthenium(III and characterized using UV-Visible, Fourier transform infrared (FTIR, 1H NMR, and mass spectroscopy. The most likely structure suggested for the ruthenium(II species is mer-[Ru(N2Me43(acacH]. Mercury poisoning experiment indicates that the catalytic dehydrogenation of dimethylamine-borane is homogeneous catalysis. The kinetics of the catalytic dehydrogenation of dimethylamine borane starting with Ru(acac3 were studied depending on the catalyst concentration, substrate concentration and temperature. The hydrogen generation was found to be first-order with respect to catalyst concentration and zero-order regarding the substrate concentration. Evaluation of the kinetic data provides the activation parameters for the dehydrogenation reaction: the activation energy Ea = 85 ± 2 kJ·mol−1, the enthalpy of activation ∆H# = 82 ± 2 kJ·mol−1 and the entropy of activation; ∆S# = −85 ± 5 J·mol−1·K−1. The ruthenium(II catalyst formed from the reduction of ruthenium(III acetylacetonate provides 1700 turnovers over 100 hours in hydrogen generation from the dehydrogenation of dimethylamine borane before deactivation at 60 °C.

  17. Catalytic oxidation of hydrocarbons by dinuclear iron complexes

    International Nuclear Information System (INIS)

    Our efforts during the past eight months were directed towards characterizing synthetic complexes that model the electronic and reactivity properties of the active site of methane monooxygenase (MMO), a metalloenzyme found in methanotrophic bacteria responsible for the biological oxidation of methane to methanol. We have investigated the structural/electronic and reactivity properties of a series of dinuclear model complexes that can function as oxygen atom transfer catalysts. In particular, our studies focused on [Fe2+2(H2Hbab)2(N-MeIM)], its DMF solvated form, [Fe2+2(H2Hbab)2(DMF)2(N-MeIM)], and the mixed valent species [[Fe2+2(H2Hbab)2(DMF)4]+, (H4Hbab = 1,2-bis(2-hydroxybenzamido) benzene). We have also examined [Fe3+2(H2Hbab)2(DMF)4]2, [Fe3+2(H2Hbab)2(OMe)2], and μ-oxo[Fe3+2(H2Hbab)2(DMF)2], which are unable to act as oxygen atom transfer catalysts

  18. Catalytic oxidation of pulping effluent by activated carbon-supported heterogeneous catalysts.

    Science.gov (United States)

    Yadav, Bholu Ram; Garg, Anurag

    2016-01-01

    The present study deals with the non-catalytic and catalytic wet oxidation (CWO) for the removal of persistent organic compounds from the pulping effluent. Two activated carbon-supported heterogeneous catalysts (Cu/Ce/AC and Cu/Mn/AC) were used for CWO after characterization by the following techniques: temperature-programmed reduction, Fourier transform infrared spectroscopy and thermo-gravimetric analysis. The oxidation reaction was performed in a batch high-pressure reactor (capacity = 0.7  L) at moderate oxidation conditions (temperature = 190°C and oxygen pressure = 0.9 MPa). With Cu/Ce/AC catalyst, the maximum chemical oxygen demand (COD), total organic carbon (TOC) and lignin removals of 79%, 77% and 88% were achieved compared to only 50% removal during the non-catalytic process. The 5-day biochemical oxygen demand (BOD5) to COD ratio (a measure for biodegradability) of the pulping effluent was improved to 0.52 from an initial value of 0.16. The mass balance calculations for solid recovered after CWO reaction showed 8% and 10% deduction in catalyst mass primarily attributed to the loss of carbon and metal leaching. After the CWO process, carbon deposition was also observed on the recovered catalyst which was responsible for around 3-4% TOC reduction. PMID:26508075

  19. Application of Catalytic Wet Air Oxidation to Treatment of Landfill Leachate on Co/Bi Catalyst

    Institute of Scientific and Technical Information of China (English)

    LI Hai-sheng; LIU Liang; ZHANG Rong; DONG De-ming; LIU Hong-liang; LI Yu

    2004-01-01

    Catalytic wet air oxidation(CWAO) was employed to reduce the organic compounds in landfill leachate and the effects of temperature, oxygen pressure, catalyst dosage, and concentration of the organic compounds on the TOC and CODCr removal rates were studied. The degradation kinetics of landfill leachate was also investigated and an exponential experiential model consisting of four influential factors was established to describe the reduction of the organic compounds in the landfill leachate. Meanwhile, the GC-MS technique was used to detect the components of the organic intermediates for the inference of the decomposition mechanisms of the organic compounds in landfill leachate. The results reveal that the reaction temperature and the catalyst dosage are the most important factors affecting the degradation reaction of the organic compounds and that the principal intermediates confirmed by GC-MS are organic acids at a percentage of more than 88% with no aldehydes or alcohols detected. The decomposition mechanisms of the organic compounds in landfill leachate were inferred based on the GC-MS information as follows: the activated gas phase O2 captured the hydrogen of the organic pollutants to produce free radicals, which then initiated the catalytic reaction. So most of the organic compounds were oxidized into CO2 and H2O ultimately. In general, catalytic wet air oxidation over catalyst Co3O4/Bi2O3 was a very promising technique for the treatment of landfill leachate.

  20. Isolated FeII on Silica As a Selective Propane Dehydrogenation Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bo; Schweitzer, Neil M.; Zhang, Guanghui; Kraft, Steven J.; Childers, David J.; Lanci, Michael P.; Miller, Jeffrey T.; Hock, Adam S.

    2015-04-17

    ABSTRACT: We report a comparative study of isolated FeII, iron oxide particles, and metallic nanoparticles on silica for non-oxidative propane dehydrogenation. It was found that the most selective catalyst was an isolated FeII species on silica prepared by grafting the open cyclopentadienide iron complex, bis(2,4-dimethyl-1,3-pentadienide) iron(II) or Fe(oCp)2. The grafting and evolution of the surface species was elucidated by 1H NMR, diffuse reflectance infrared Fourier transform spectroscopy and X-ray absorption spectroscopies. The oxidation state and local structure of surface Fe were characterized by X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure. The initial grafting of iron proceeds by one surface hydroxyl Si-OH reacting with Fe(oCp)2 to release one diene ligand (oCpH), generating a SiO2-bound FeII(oCp) species, 1-FeoCp. Subsequent treatment with H2 at 400 °C leads to loss of the remaining diene ligand and formation of nanosized iron oxide clusters, 1-C. Dispersion of these Fe oxide clusters occurs at 650 °C, forming an isolated, ligand-free FeII on silica, 1-FeII, which is catalytically active and highly selective (~99%) for propane dehydrogenation to propene. Under reaction conditions, there is no evidence of metallic Fe by in situ XANES. For comparison, metallic Fe nanoparticles, 2-NP-Fe0, were independently prepared by grafting Fe[N(SiMe3)2]2 onto silica, 2-FeN*, and reducing it at 650 °C in H2. The Fe NPs were highly active for propane conversion but showed poor selectivity (~14%) to propene. Independently prepared Fe oxide clusters on silica display a low activity. The sum of these results suggests that selective propane dehydrogenation occurs at isolated FeII sites.

  1. Alkali Metals Promoted Co-Mn-Al Mixed Oxide for N2O Catalytic Decomposition

    Czech Academy of Sciences Publication Activity Database

    Karásková, K.; Kulová, T.; Obalová, L.; Jirátová, Květa; Kovanda, F.

    Bratislava : Slovak Society of Chemical Engineering, 2011 - (Markoš, J.), s. 251 ISBN 978-80-227-3503-2. [International Conference of Slovak Society of Chemical Engineering /38./. Tatranské Matliare (SK), 23.05.2011-27.05.2011] R&D Projects: GA ČR GA106/09/1664 Grant ostatní: GA MŠk ED2.1.00/03.0100 Institutional research plan: CEZ:AV0Z40720504 Keywords : nitrous oxide * catalytic decomposition * mixed oxide catalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  2. Exoemission and catalytic activity of oxides of the perovskite and spinel structures in the processes of CO and hydrocarbons oxidation

    International Nuclear Information System (INIS)

    Low-temperature (20-400 deg C) exoemission of negative charges from complex oxides featuring perovskite structure AMO3 (A = La; M = Co, Mn, Ni) and spinel structure A'M'2O4 (A' = Cu; M' = Fe, Co, Cr) was studied using the Geiger gas-flow counter. The experiments were carried out under conditions of thermally induced emission, photo- and thermally induced emission during irradiation of samples by UV light with the wavelength of 313 nm, as well as thermally induced emission under effect of β-radiation of 90Y-90Sr with dose of 0.23 Gy. Correlation between emissivity of the oxides and catalytic activity was established. The role of weakly bound oxygen and variable valency ions in exoemission and oxidizing catalysis processes involving the complex oxides was discussed

  3. Catalytic combustion of methane by perovskite-type oxide nanoparticles as pollution prevention strategy

    Science.gov (United States)

    Zaza, F.; Luisetto, I.; Serra, E.; Tuti, S.; Pasquali, M.

    2016-06-01

    The transition from the existing brown economy towards the desired green economy drives the research efforts to the development of advanced technologies promoting the efficient utilization of energy sources. Catalysis science offers to combustion technology significant opportunity to increase the fuel efficiency by lowering the internal temperature gradients and reduce the environmental impact by lowering local peak temperature and, consequently, thermodynamically inhibiting the nitrogen oxides formation. Alternative catalytic materials are transition metals oxide, including complex oxides with perovskite crystalline structure. The aim of this work is to synthetize lanthanum ferrite perovskites with lanthanum ions partially substituted by strontium ions in order to study the substitution effects on structural properties and redox activity of the original oxide. Lanthanum ferrite oxides partially substituted with different Strontium amount were synthesized by solution combustion method. The perovskite nanopowders obtained were characterized by XRD, SEM, TPR analyses for defining crystalline structure, morphology and redox properties. Finally, the catalytic activity for methane combustion was tested. The most performing catalysts was La0.6Sr0.4FeO3 having the highest oxygen vacancy concentration as revealed by TPR analysis.

  4. Catalytic performance of Fe-ZSM-5 catalysts for selective catalytic reduction of nitric oxide by ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Long, R.Q.; Yang, R.T.

    1999-12-10

    A series of Fe-exchanged molecular sieves were studied as catalysts for the selective catalytic reduction (SCR) of NO with ammonia. It was found that Fe-ZSM-5 and Fe-mordenite catalysts were highly active for the SCR reaction. Nearly 100% NO conversions were obtained at 400--500 C under conditions with a high space velocity (GHSV = 4.6 x 10{sup 5} 1/h). However, Fe-Y and Fe-MCM-41 with larger pore sizes showed lower activities for this reaction. F or Fe-ZSM-5 catalysts, the SCR activity decreased with increasing Si/Al ratio in the zeolites. As the Fe-exchange level in the Fe-ZSM-5 catalysts was increased from 58 to 252%, NO conversion increased at lower temperatures (e.g., 300 C), but decreased at high temperatures (e.g., 600 C). Compared with the commercial vanadia catalyst, based on the first-order rate constants, the Fe-ZSM-5 catalyst was five times more active at 400 C and seven times more active at 450 C. It also functioned in a broader temperature window, produced only N{sub 2} (rather than N{sub 2}O) and H{sub 2}O, and showed a substantially lower activity for oxidation of SO{sub 2} to SO{sub 3}.

  5. Heterogeneous catalytic ozonation of ciprofloxacin in water with carbon nanotube supported manganese oxides as catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sui, Minghao, E-mail: suiminghao.sui@gmail.com [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Xing, Sichu; Sheng, Li; Huang, Shuhang; Guo, Hongguang [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Ciprofloxacin in water was degraded by heterogeneous catalytic ozonation. Black-Right-Pointing-Pointer MnOx were supported on MWCNTs to serve as catalyst for ozonation. Black-Right-Pointing-Pointer MnOx/MWCNT exhibited highly catalytic activity on ozonation of ciprofloxacin in water. Black-Right-Pointing-Pointer MnOx/MWCNT resulted in effective antibacterial activity inhibition on ciprofloxacin. Black-Right-Pointing-Pointer MnOx/MWCNT promoted the generation of hydroxyl radicals. - Abstract: Carbon nanotube-supported manganese oxides (MnOx/MWCNT) were used as catalysts to assist ozone in degrading ciprofloxacin in water. Manganese oxides were successfully loaded on multi-walled carbon nanotube surfaces by simply impregnating the carbon nanotube with permanganate solution. The catalytic activities of MnOx/MWCNT in ciprofloxacin ozonation, including degradation, mineralization effectiveness, and antibacterial activity change, were investigated. The presence of MnOx/MWCNT significantly elevated the degradation and mineralization efficiency of ozone on ciprofloxacin. The microbiological assay with a reference Escherichia coli strain indicated that ozonation with MnOx/MWCNT results in more effective antibacterial activity inhibition of ciprofloxacin than that in ozonation alone. The effects of catalyst dose, initial ciprofloxacin concentration, and initial pH conditions on ciprofloxacin ozonation with MnOx/MWCNT were surveyed. Electron spin resonance trapping was applied to assess the role of MnOx/MWCNT in generating hydroxyl radicals (HO{center_dot}) during ozonation. Stronger 5,5-dimethyl-1-pyrroline-N-oxide-OH signals were observed in the ozonation with MnOx/MWCNT compared with those in ozonation alone, indicating that MnOx/MWCNT promoted the generation of hydroxyl radicals. The degradation of ciprofloxacin was studied in drinking water and wastewater process samples to gauge the potential effects of water background matrix on

  6. Enhanced catalytic oxidation ability of ternary layered double hydroxides for organic pollutants degradation.

    Science.gov (United States)

    Fahel, Jean; Kim, Sanghoon; Durand, Pierrick; André, Erwan; Carteret, Cédric

    2016-05-10

    Co(2+) and Cu(2+) substituted MgAl layered double hydroxides with an M(2+)/M(3+) atomic ratio of 2.0 were synthesized by a co-precipitation method and fully characterized using various techniques including powder X-ray diffraction, ICP-AES analysis, FT-IR, DR UV-Vis spectroscopy, N2 adsorption-desorption and transmission electron microscopy. The materials revealed a good crystallinity with no phase impurity and successful substitution of cobalt and copper ions in the framework of binary LDH with the target ratio of metals in the sheet. The adsorption characteristics (kinetic and isotherm) and the catalytic oxidation of organic pollutants, methylene blue (cationic dye) and orange II (anionic) were carried out to investigate a potential use of LDH materials as catalysts. In particular, Co3Cu1Al2 LDH exhibited an excellent catalytic activity towards catalytic dye degradation, especially for orange II with good stability and reusability over several times. Furthermore, this LDH material showed good catalytic performance for several chlorophenol compounds, suggesting its practical application in wastewater treatment. Therefore, layered double hydroxides substituted with Co(2+) and Cu(2+) could be promising candidates in various applications, such as the abatement of organic pollutants. PMID:27097543

  7. Intrinsic catalytic properties of extruded clay honeycomb monolith toward complete oxidation of air pollutants.

    Science.gov (United States)

    Assebban, Mhamed; El Kasmi, Achraf; Harti, Sanae; Chafik, Tarik

    2015-12-30

    The present work highlights the intrinsic catalytic properties of extruded clay honeycomb monolith toward complete oxidation of various air pollutants namely CO, methane, propane, acetylene, propene, n-butene, methanol, ethanol, n-propanol, n-butanol, acetone, dimethyl ether, benzene, toluene, o-xylene, monochlorobenzene and 1,2-dichlorobenzene. Total catalytic conversion was achieved for all tested compounds with different behaviors depending on pollutants' structural and chemical nature. The comparison of T50 values obtained from light-off curves allowed the establishment of the following reactivity sequence: ketone>alcohol>ether>CO>alkyne>aromatic>alkene>chlorinated aromatic>alkane. The intrinsic catalytic performances of the natural clay was ascribed to the implication of a quite complex mixture constituted by OH groups (Brønsted acids) and coordinately-unsaturated cations, such as Al(3+), Fe(3+) and Fe(2+) (Lewis acids). Hence, the combination of the clay's intrinsic catalytic performances and easier extrudability suggests a promissory potential for application in air pollution control. PMID:26259164

  8. Ethylbenzene dehydrogenation over FeOx/(Mg,Zn)(Al)O catalysts derived from hydrotalcites: Role of MgO as basic sites

    KAUST Repository

    Balasamy, Rabindran J.

    2011-05-01

    A series of Mg3-xZnxFe0.5Al0.5 mixed oxide catalysts derived from hydrotalcites were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The catalysts were prepared by coprecipitation from the nitrates of metal components followed by calcination to mixed oxides at 550 °C. A part of Mg2+ in Mg 3Fe0.5Al0.5 mixed oxide was replaced with Zn2+ to test the effect of MgO as the support. The mixed oxides were composed of periclase and spinel-type compounds with a high surface area of 100-180m2gcat-1. Mössbauer and XPS measurements indicated the presence of Fe3+ on the catalysts and H2-TPR measurement suggested that the dehydrogenation reaction is catalyzed by the reduction-oxidation between Fe3+/Fe2+. The activity of Mg3-xZnxFe0.5Al0.5 mixed oxide decreased with increasing x, indicating an important role of MgO on the activity. Both CO2-TPD measurements as well as IR measurements of adsorbed CO2 clearly indicated the presence of basic sites of Mg 2+O2- on the catalysts. It seems that the combination of Mg2+O2- and Fe3+ was essential for the catalytic activity. It is concluded that the surface base sites generated on O2- bound Mg2+ near Fe3+ sites are responsible for H+-abstraction; the dehydrogenation of ethylbenzene was initiated by the H+ abstraction on Mg2+O2- basic sites, and accelerated by the reduction-oxidation of Fe3+/Fe2+ active species. © 2011 Elsevier B.V.

  9. Catalytic oxidation of N-methyldiphenylamine-4-sulfonic acid in weakly acid solutions: a study by radiospectroscopic methods

    International Nuclear Information System (INIS)

    The mechanism of the catalytic oxidation of N-methyldiphenylamine-4-sulfonic acid (MDPASA) in weakly acid (10-3 M H2SO4) solutions is studied by EPR and 1H NMR spectroscopy. It is shown that the oxidation of the reagent with potassium periodate in the presence of ruthenium(4) proceeds through the radical mechanism that includes alternate steps of the oxidation and reduction of the catalyst. The suggested mechanism of the catalytic oxidation of MDPASA gave theoretical grounds to the conditions for the determination of ruthenium by kinetic methods that were selected previously in the basis of experimental data

  10. Binary [Cu2O/MWCNT] and ternary [Cu2O/ZnO/MWCNT] nanocomposites: formation, characterization and catalytic performance in partial ethanol oxidation

    Science.gov (United States)

    Khanderi, Jayaprakash; Contiu, Cosmin; Engstler, Jörg; Hoffmann, Rudolf C.; Schneider, Jörg J.; Drochner, Alfons; Vogel, Herbert

    2011-03-01

    Cuprous oxide agglomerates composed of 4-10 nm Cu2O nanoparticles were deposited on multiwalled carbon nanotubes (MWCNTs) and on ZnO/MWCNTs to give binary [Cu2O/MWCNT] and ternary [Cu2O/ZnO/MWCNT] composites. Di-aqua-bis[2-(methoxyimino)propanoato]copper Cu[O2CCCH3NOMe]2.2H2O 1 in DMF was used as single source precursor for the deposition of nanoscaled Cu2O. The precursor decomposes either in air or under argon to yield CuO2 by in situ redox reaction. Thermogravimetric coupled mass spectroscopic analysis (TG-MS) of 1 revealed that methanol formed during the decomposition of 1 acts as a potential in situ reducing agent. Scanning electron microscopy (SEM) of the binary [Cu2O/MWCNT] nano-composite shows an increase of cuprous oxide loading depending on the precursor amount, along the periphery of the MWCNTs as well as formation of larger particle agglomerates. Transmission electron microscopy (TEM) of the sample shows crystalline domains of size 4-10 nm surrounded by an amorphous region within the larger particles. SEM and TEM of ternary [Cu2O/ZnO/MWCNT] clearly reveal that Cu2O nanoparticles are primarily deposited on ZnO rather than on MWCNTs. The catalytic activities of the [Cu2O/MWCNT] and [Cu2O/ZnO/MWCNT] binary and ternary composites were studied for the selective partial oxidation of ethanol to acetaldehyde with molecular oxygen. While using binary [Cu2O/MWCNT] (13.8 wt% Cu) as catalyst, acetaldehyde was obtained with a yield of 87% at 355 °C (selectivity 96% and conversion 91%). When nanoscale ZnO is present, the resulting [Cu2O/ZnO/MWCNT] composite shows preferential hydrogen and CO2 formation due to the fact that the dehydrogenation and total oxidation pathway is more favoured compared to the binary composite. Significant morphological changes of the catalyst during the catalytic process were observed.Cuprous oxide agglomerates composed of 4-10 nm Cu2O nanoparticles were deposited on multiwalled carbon nanotubes (MWCNTs) and on ZnO/MWCNTs to give binary [Cu

  11. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    Science.gov (United States)

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-09-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested.

  12. Reduced graphene oxide supported platinum nanocubes composites: one-pot hydrothermal synthesis and enhanced catalytic activity

    International Nuclear Information System (INIS)

    Reduced graphene oxide (rGO) supported platinum nanocubes (Pt-NCs) composites (Pt-NCs/rGO) were synthesized successfully by a water-based co-chemical reduction method, in which polyallylamine hydrochloride acted as a multi-functional molecule for the functionalization of graphene oxide, anchorage of PtII precursor, and control of Pt crystal facets. The morphology, structure, composition, and catalytic property of Pt-NCs/rGO composites were characterized in detail by various spectroscopic techniques. Transmission electron microscopy images showed well-defined Pt-NCs with an average size of 9 nm uniformly distributed on the rGO surface. The as-prepared Pt-NCs/rGO composites had excellent colloidal stability in the aqueous solution, and exhibited superior catalytic activity towards the hydrogenation reduction of nitro groups compared to commercial Pt black. The improved catalytic activity originated from the abundant exposed Pt{100} facets of Pt-NCs, excellent dispersion of Pt-NCs on the rGO surface, and synergistic effect between Pt-NCs and rGO. (paper)

  13. Magnetic bimetallic nanoparticles supported reduced graphene oxide nanocomposite: Fabrication, characterization and catalytic capability

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei; Wu, Tao; Xu, Xiaoyang; Xia, Fengling; Na, Heya [School of Science, Tianjin University, Tianjin 300072 (China); Liu, Yu, E-mail: liuyuls@163.com [School of Science, Tianjin University, Tianjin 300072 (China); Qiu, Haixia [School of Science, Tianjin University, Tianjin 300072 (China); Wang, Wei [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Gao, Jianping, E-mail: jianpinggao2012@126.com [School of Science, Tianjin University, Tianjin 300072 (China)

    2015-04-15

    Highlights: • Ni and Ag nanoparticles loaded on RGO (Ni–Ag@RGO) were fabricated in a one-pot reaction. • The Ni–Ag@RGO were excellent catalysts for the reduction of 4-nitrophenol. • The Ni–Ag@RGO showed superior catalytic activity for photodegradation of methyl orange. • The Ni–Ag@RGO exhibit good reusability in a magnetic field. - Abstract: A facile method for preparing Ni–Ag bimetallic nanoparticles supported on reduced graphene oxide (Ni–Ag@RGO hybrid) has been established. Hydrazine hydrate was used as the reducing agent to reduce the graphene oxide, Ni{sup 2+} and Ag{sup +} to form Ni–Ag@RGO hybrid. The prepared hybrid was further characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. Interestingly, the prepared material shown good magnetic properties, which were determined by vibrating sample magnetometer. In addition, the Ni–Ag@RGO hybrid exhibited excellent catalytic activity for the reduction of 4-nitrophenol and the photodegradation of methyl orange. The catalytic process was monitored by determining the change in the concentration of the reactants with time using ultraviolet–visible absorption spectroscopy. After completion of the reaction, the catalyst can be separated from the reaction system simply under a magnet field and shows good recyclability.

  14. Catalytic oxidation of albendazole using molybdenum supported on carbon nanotubes as catalyst

    International Nuclear Information System (INIS)

    The catalytic oxidation reaction of the thioether group (-S-) in the structure to the drug albendazole (C12H15N3O2S) was studied in order to obtain a pharmacologically active molecule known as albendazole sulfoxide. With this purpose, three heterogeneous catalysts were prepared using molybdenum (Mo) as active phase and carbon nanotubes as a multiple-layer catalyst support. The incorporation of the active phase was performed by wet impregnation, with subsequent calcination for 4 hours at 400 oC. For the catalytic oxidation reaction was employed hydrogen peroxide-urea (H2NCONH2·H2O2) as oxidizing agent and methanol (CH3OH) as reaction medium. The textural and morphology characterization of carbon nanoparticles and catalysts was carried out by adsorption-desorption of N2 (BET) and scanning electron microscopy (SEM). The identification and quantification of the reaction products were followed by Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC), respectively. With the yield, selectivity and conversion higher than 90% after 60 minutes of reaction, albendazole sulphoxide was obtained as major product of oxidation reaction. (author)

  15. Oxidative catalytic evolution of redox- and spin-states of a Fe-phthalocyanine studied by EPR

    Science.gov (United States)

    Bletsa, Eleni; Solakidou, Maria; Louloudi, Maria; Deligiannakis, Yiannis

    2016-04-01

    The catalytic-oxidative evolution of the redox/spin states of a Fe-phthalocyanine (Fe-Pc) catalyst was studied by electron paramagnetic resonance spectroscopy. Under oxidative catalytic conditions, Fe-Pc may evolve via multiple redox/spin conformations. Axial ligation of imidazole, O2 or t-Bu-OOH as oxidant, results in a complex multipath redox/spin landscape that was determined in detail herein. The high-spin conformations of Fe-Pc/imidazole evolve more slowly than the low-spin conformations. Catalytically active vs. inactive conformations were distinguished. A unified physicochemical catalytic reaction mechanism is discussed herein based on the distinct role of the various structural, spin and redox forms.

  16. Highly n-Type Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

    KAUST Repository

    Baker, L. Robert

    2011-08-18

    The role of the oxide-metal interface in determining the activity and selectivity of chemical reactions catalyzed by metal particles on an oxide support is an important topic in science and industry. A proposed mechanism for this strong metal-support interaction is electronic activation of surface adsorbates by charge carriers. Motivated by the goal of using electronic activation to drive nonthermal chemistry, we investigated the ability of the oxide support to mediate charge transfer. We report an approximately 2-fold increase in the turnover rate of catalytic carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titanium dioxide (TiO2) when the TiO2 is made highly n-type by fluorine (F) doping. However, for nonstoichiometric titanium oxide (TiOX<2) the effect of F on the turnover rate is negligible. Studies of the titanium oxide electronic structure show that the energy of free electrons in the oxide determines the rate of reaction. These results suggest that highly n-type TiO2 electronically activates adsorbed oxygen (O) by electron spillover to form an active O- intermediate. © 2011 American Chemical Society.

  17. Communication: Towards catalytic nitric oxide reduction via oligomerization on boron doped graphene

    Science.gov (United States)

    Cantatore, Valentina; Panas, Itai

    2016-04-01

    We use density functional theory to describe a novel way for metal free catalytic reduction of nitric oxide NO utilizing boron doped graphene. The present study is based on the observation that boron doped graphene and O—N=N—O- act as Lewis acid-base pair allowing the graphene surface to act as a catalyst. The process implies electron assisted N=N bond formation prior to N—O dissociation. Two N2 + O2 product channels, one of which favoring N2O formation, are envisaged as outcome of the catalytic process. Besides, we show also that the N2 + O2 formation pathways are contrasted by a side reaction that brings to N3O3- formation and decomposition into N2O + NO2-.

  18. Selective catalytic reduction of nitrogen oxides from industrial gases by hydrogen or methane

    International Nuclear Information System (INIS)

    This work deals with the selective catalytic reduction of nitrogen oxides (NOx), contained in the effluents of industrial plants, by hydrogen or methane. The aim is to replace ammonia, used as reducing agent, in the conventional process. The use of others reducing agents such as hydrogen or methane is interesting for different reasons: practical, economical and ecological. The catalyst has to convert selectively NO into N2, in presence of an excess of oxygen, steam and sulfur dioxide. The developed catalyst is constituted by a support such as perovskites, particularly LaCoO3, on which are dispersed noble metals (palladium, platinum). The interaction between the noble metal and the support, generated during the activation of the catalyst, allows to minimize the water and sulfur dioxide inhibitor phenomena on the catalytic performances, particularly in the reduction of NO by hydrogen. (O.M.)

  19. Catalytic effects of trace ruthenium on oxidation of dimethyl yellow with bromate and its application

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-rong; WANG Qun; ZHANG Shu-yuan

    2008-01-01

    A spectrophotometric method for the determination of ruthenium(Ⅲ) is described, based on its catalytic effect on the oxidation reaction of dimethyl yellow (DMY) with potassium bromate in an acid solution medium and in the presence of an OP emulsifier (p-iso-octyl phenoxy polyethoxy ethanol) at 100 ℃. This reaction was followed spectrophotometrically by measuring the decrease in the absorbance at 530 nm of the catalytic reaction of DMY. The calibration curve for the recommended method was linear in the concentration range over 0.0-1.0 μg/Land the detection limit of the method for Ru(Ⅲ) was 0.01 μg/L. The method is highly sensitive, selective and very stable and has been successfully applied for the determination of trace amounts of ruthenium in some ores and metallurgy products with the relative standard deviations (RSD) over 1.6%-2.8% and a recovery over 98.7%-104.0%.

  20. Heterogeneous catalytic ozonation of ciprofloxacin in water with carbon nanotube supported manganese oxides as catalyst

    International Nuclear Information System (INIS)

    Highlights: ► Ciprofloxacin in water was degraded by heterogeneous catalytic ozonation. ► MnOx were supported on MWCNTs to serve as catalyst for ozonation. ► MnOx/MWCNT exhibited highly catalytic activity on ozonation of ciprofloxacin in water. ► MnOx/MWCNT resulted in effective antibacterial activity inhibition on ciprofloxacin. ► MnOx/MWCNT promoted the generation of hydroxyl radicals. - Abstract: Carbon nanotube-supported manganese oxides (MnOx/MWCNT) were used as catalysts to assist ozone in degrading ciprofloxacin in water. Manganese oxides were successfully loaded on multi-walled carbon nanotube surfaces by simply impregnating the carbon nanotube with permanganate solution. The catalytic activities of MnOx/MWCNT in ciprofloxacin ozonation, including degradation, mineralization effectiveness, and antibacterial activity change, were investigated. The presence of MnOx/MWCNT significantly elevated the degradation and mineralization efficiency of ozone on ciprofloxacin. The microbiological assay with a reference Escherichia coli strain indicated that ozonation with MnOx/MWCNT results in more effective antibacterial activity inhibition of ciprofloxacin than that in ozonation alone. The effects of catalyst dose, initial ciprofloxacin concentration, and initial pH conditions on ciprofloxacin ozonation with MnOx/MWCNT were surveyed. Electron spin resonance trapping was applied to assess the role of MnOx/MWCNT in generating hydroxyl radicals (HO·) during ozonation. Stronger 5,5-dimethyl-1-pyrroline-N-oxide–OH signals were observed in the ozonation with MnOx/MWCNT compared with those in ozonation alone, indicating that MnOx/MWCNT promoted the generation of hydroxyl radicals. The degradation of ciprofloxacin was studied in drinking water and wastewater process samples to gauge the potential effects of water background matrix on MnOx/MWCNT catalytic ozonation.

  1. Influence of physicochemical treatments on spent palladium based catalyst for catalytic oxidation of VOCs.

    Science.gov (United States)

    Kim, Sang Chai; Nahm, Seung Won; Shim, Wang Geun; Lee, Jae Wook; Moon, Hee

    2007-03-01

    To recycle the spent catalyst for the removal of VOCs, the benzene, toluene, and xylene (BTX) complete oxidations were studied over pretreated palladium based spent catalyst in a fixed bed flow reactor system at atmospheric pressure. Two different pretreatment methods with gas (air and hydrogen) and acid aqueous solution (HCl, H(2)SO(4), HNO(3), H(3)PO(4) and CH(3)COOH) were used to investigate the catalytic activity of spent catalyst. The properties of the spent and pretreated Pd based catalyst were characterized by XRD, BET, TEM, ICP, and XPS. The results of light-off curves indicate that the catalytic activity of toluene oxidation for pretreated samples is in the order of hydrogen>air>HNO(3)>CH(3)COOH>H(2)SO(4)>H(3)PO(4)>HCl. In addition, the air and the acid aqueous pretreated catalyst activities were significantly decreased compared to that of the spent (or parent) catalyst. Moreover, hydrogen pretreated (or reduced) catalysts having mainly metallic form show the best performance in removing the toluene vapours compared to other pretreated samples. The reduction temperature made a significant difference in the catalytic performance of the spent catalyst pretreated with hydrogen. XPS results clearly supported that the palladium state of the spent catalysts pretreated at 300 degrees C was shifted more toward metallic form than other reduced catalysts. Furthermore, the results of a long-term test and catalytic activity of aromatic hydrocarbons also supported that the hydrogen pretreated spent catalyst was a good candidate for removing toxic compounds. PMID:16919389

  2. Catalytic combustion of benzene over CuO-CeO2 mixed oxides.

    Science.gov (United States)

    Jung, Won Young; Lim, Kwon-Taek; Hong, Seong-Soo

    2014-11-01

    Catalytic combustion of benzene over CuO-CeO2 mixed oxides has been investigated. The CuO-CeO2 mixed oxides were prepared by the combustion method using malic acid as an organic fuel and characterized by XRD, XPS and TPR. For the CuO-CeO2 catalyst with a Cu/(Cu + Ce) molar ratio of more than 0.4, highly dispersed copper oxide species were shown at 2θ = 35.5 degrees and 38.8 degrees. The CuO-CeO2 catalyst prepared using 2.0 M malic acid showed the highest activity, with conversion reaching nearly 100% at 350 degrees C. In addition, the highest activity is shown on Cu0.40 (the index denotes the molar ratio Cu/(Cu + Ce)) sample and then it decreases on Cu0.5 and Cu0.7 samples. PMID:25958554

  3. Electro-catalytic effect of manganese oxide on oxygen reduction at teflonbonded carbon electrode

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Oxygen reduction(OR)on Teflon-bonded carbon electrodes with manganese oxide as catalyst in 6 mol/L KOH solution was investigated using AC impedance spectroscopy combined with other techniques. For OR at this electrode, the Tafel slope is-0.084V/dec and the apparent exchange current density is (1.02-3.0)×10-7 A/cm2. In the presence of manganese oxide on carbon electrode,the couple Mn3+/Mn4+ reacts with the O2 adsorbed on carbon sites forming O2- radicals and acceletes the dismutation of O2-, which contributes to the catalytic effect of manganese oxide for OR reaction.

  4. Catalytic wet oxidation of thiocyanate with homogeneous copper(II) sulphate catalyst

    International Nuclear Information System (INIS)

    The wet oxidation of thiocyanate has been investigated in a semi-batch reactor at temperatures between 423 and 473 K and pressures between 6.1 x 103 and 1.0 x 104 kPa in the presence of copper(II) sulphate as catalyst. The effects of copper concentration, initial thiocyanate concentration, pressure and temperature on the reaction rate were analyzed and the main products of reaction were identified. A kinetic model for the Cu-catalyzed reaction is here proposed, including temperature, oxygen concentration, and the reduction of Cu2+ to Cu+ that gives an accurate prediction of the oxidation process under the assayed conditions. A mechanistic model based on the formation of a transition complex between a copper cation and two thiocyanate anions has been proposed for the catalytic wet oxidation.

  5. Catalytic ozonation of sulfosalicylic acid over manganese oxide supported on mesoporous ceria.

    Science.gov (United States)

    Xing, Shengtao; Lu, Xiaoyang; Liu, Jia; Zhu, Lin; Ma, Zichuan; Wu, Yinsu

    2016-02-01

    Manganese oxide supported on mesoporous ceria was prepared and used as catalyst for catalytic ozonation of sulfosalicylic acid (SA). Characterization results indicated that the manganese oxide was mostly incorporated into the pores of ceria. The synthesized catalyst exhibited high activity and stability for the mineralization of SA in aqueous solution by ozone, and more than 95% of total organic carbon was removed in 30 min under various conditions. Mechanism studies indicated that SA was mainly degraded by ozone molecules, and hydroxyl radical reaction played an important role for the degradation of its ozonation products (small molecular organic acids). The manganese oxide in the pores of CeO2 improved the adsorption of small molecular organic acids and the generation of hydroxyl radicals from ozone decomposition, resulting in high TOC removal efficiency. PMID:26344143

  6. Catalytic selective oxidation or oxidative functionalization of methane and ethane to organic oxygenates

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Selective oxidation or oxidative functionalization of methane and ethane by both homogeneous and heterogeneous catalysis is presented concerning: (1) selective oxidation of methane and ethane to organic oxygenates by hydrogen peroxide in a water medium in the presence of homogeneous osmium catalysts, (2) selective oxidation of methane to formaldehyde over highly dispersed iron and copper heterogeneous catalysts, (3) selective oxidation of ethane to acetaldehyde and formaldehyde over supported molybdenum catalysts, and (4) oxidative carbonylation of methane to methyl acetate over heterogeneous catalysts containing dual sites of rhodium and iron.

  7. Catalytic effects on methanol oxidation produced by cathodization of platinum electrodes.

    Science.gov (United States)

    Díaz, Verónica; Zinola, Carlos F

    2007-09-01

    A catalytic effect is found for methanol oxidation after new active surface states are produced on polycrystalline platinum by potentiostatic cathodization in acid media at room temperature. This procedure originates surface states not available on the original polycrystalline electrodes with unexpected cyclic voltammetric responses; i.e., at least four new peaks below 0.9 V are observed. The cathodization process also induces a rearrangement of the bulk platinum oxide, showing a defined peak at 1.2 V. The appearance of these new states is also proven by open-circuit potential decays. The electrocatalytic activity of these new surfaces in methanol oxidation is compared with that of the untreated electrodes by electrochemical impedance spectroscopy, chronoamperometry, and cyclic voltammetry. The cathodic procedure enhances the methanol oxidation voltammetric current peaks with charge density values higher than those on untreated platinum. The integration of chronoamperometric plots over 10 min in methanol acid media presents the largest difference between 0.6 and 0.7 V with respect to the original surface. Analysis of the impedance data shows that the values of polarization resistance for methanol oxidation on the cathodically treated platinum are lower than those of the original surface. According to the time constant values for methanol oxidation, the original surface can be considered less tolerant of the formation of catalytic poisons. A discussion of the most likely mechanism for the formation of the new active sites on platinum is presented here, assuming the presence of hydrogen subsurface states, ordered water clusters, and low-coordinated platinum atoms. PMID:17543323

  8. Dynamics of ultrathin V-oxide layers on Rh(111) in catalytic oxidation of ammonia and CO.

    Science.gov (United States)

    von Boehn, B; Preiss, A; Imbihl, R

    2016-07-20

    Catalytic oxidation of ammonia and CO has been studied in the 10(-4) mbar range using a catalyst prepared by depositing ultra-thin vanadium oxide layers on Rh(111) (θV ≈ 0.2 MLE). Using photoemission electron microscopy (PEEM) as a spatially resolving method, we observe that upon heating in an atmosphere of NH3 and O2 the spatial homogeneity of the VOx layer is removed at 800 K and a pattern consisting of macroscopic stripes develops; at elevated temperatures this pattern transforms into a pattern of circular VOx islands. Under reaction conditions the neighboring VOx islands become attracted by each other and coalesce. Similar processes of pattern formation and island coalescence are observed in catalytic CO oxidation. Reoxidation of the reduced VOx catalyst proceeds via surface diffusion of oxygen adsorbed onto Rh(111). A pattern consisting of macroscopic circular VOx islands can also be obtained by heating a Rh(111)/VOx catalyst in pure O2. PMID:27380822

  9. Catalytic oxidation of anionic surfactants by electrochemical oxidation with CuO-Co2O3-PO43- modified kaolin

    International Nuclear Information System (INIS)

    A new catalytic oxidation of anionic surfactants by electrochemistry method was designed and used to investigate the removal of anionic surfactant from simulated wastewater. Synergetic effect on COD removal was studied when integrating the electrochemical reactor, using porous graphite as anode and cathode, with the effective CuO-Co2O3-PO43- modified kaolin catalyst in a single undivided cell. The result showed that this combined process could effectively remove anionic surfactant. Its COD removal efficiency was much higher than those individual processes and could reach up to 90% in 60 min. The operating parameters such as initial pH, cell voltage, and current intensity were also investigated. Possible theory for COD removal was also proposed to predict the role of modified kaolin, electro-catalysis and oxidation in the combined process. The pollutants in wastewater could be decreased by the high reactive OH· that produced on the surface of catalyst by the decomposition of electrochemical generated H2O2. The result indicates that the catalytic oxidation by electrochemistry method is a promising wastewater treatment technique

  10. Simultaneous removal of methylene blue and copper(II) ions by photoelectron catalytic oxidation using stannic oxide modified iron(III) oxide composite electrodes

    International Nuclear Information System (INIS)

    Highlights: • Photoelectron catalytic oxidation was used for methylene blue and Cu2+ removal. • SnO2/Fe2O3 was prepared and characterized for use as photoanodes and photocathodes. • Optimal reaction conditions were determined for methylene blue and Cu2+ removal. • Methylene blue removal followed the Langmuir–Freundlich–Hinshelwood kinetic model. • Cu2+ removal followed the first-order rate model. - Abstract: Stannic oxide modified Fe(III) oxide composite electrodes (SnO2/Fe2O3) were synthesized for simultaneously removing methylene blue (MB) and Cu(II) from wastewater using photoelectron catalytic oxidation (PEO). The SnO2/Fe2O3 electrodes were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoelectrochemical techniques. The removal of MB and Cu(II) by PEO using the SnO2/Fe2O3 composite electrodes was studied in terms of reaction time, electric current density, and pH of the electrolyte. The kinetics of the reactions were investigated using batch assays. The optimal reaction time, pH, and electric current density of the PEO process were determined to be 30 min, 6.0, and 10 mA/cm2, respectively. The removal rates of MB from wastewater treated by PEO and electron catalytic oxidation process were 84.87% and 70.64%, respectively, while the recovery rates of Cu(II) were 91.75% and 96.78%, respectively. The results suggest that PEO is an effective method for the simultaneous removal of MB and Cu(II) from wastewater, and the PEO process exhibits a much higher removal rate for MB and Cu(II) compared to the electron catalytic oxidation process. Furthermore, the removal of MB was found to follow the Langmuir–Freundlich–Hinshelwood kinetic model, whereas the removal of Cu(II) fitted well to the first-order reaction model

  11. In situ synchrotron X-ray diffraction study on the dehydrogenation behavior of LiAlH{sub 4}–MgH{sub 2} composites

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Wei-Che; Yang, Cheng-Hsien; Tan, Chia-Yen [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Tsai, Wen-Ta, E-mail: wttsai@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan, Taiwan (China)

    2014-06-25

    Highlights: • The dehydrogenation behavior of LiAlH{sub 4}–MgH{sub 2} composites was investigated. • LiAlH{sub 4} and MgH{sub 2} exhibited mutual catalytic effects in their dehydrogenation reaction. • Composition dependent dehydrogenation behavior was observed. • Dehydrogenation reaction steps and products were identified. - Abstract: Dehydrogenation behavior of LiAlH{sub 4}–MgH{sub 2} composites was investigated by using thermal gravimetric analysis (TGA) and in situ synchrotron X-ray diffraction (XRD) technique. The experimental results showed that MgH{sub 2} could play a catalytic role in lowing the initial dehydrogenation temperature of LiAlH{sub 4}. Besides, MgH{sub 2} could be destabilized by the dehydrogenation reaction products of LiAlH{sub 4}. The initial dehydrogenation temperature of LiAlH{sub 4}–MgH{sub 2} composites was as low as 145 °C and MgH{sub 2} could decompose below 300 °C. The compounds such as LiMgAlH{sub 6}, Al{sub 3}Mg{sub 2}, Al{sub 12}Mg{sub 17} and Li{sub 0.92}Mg{sub 4.08} formed during dehydrogenation process suggested some mutual reactions proceeded between LiAlH{sub 4} and MgH{sub 2}.

  12. In situ synchrotron X-ray diffraction study on the dehydrogenation behavior of LiAlH4–MgH2 composites

    International Nuclear Information System (INIS)

    Highlights: • The dehydrogenation behavior of LiAlH4–MgH2 composites was investigated. • LiAlH4 and MgH2 exhibited mutual catalytic effects in their dehydrogenation reaction. • Composition dependent dehydrogenation behavior was observed. • Dehydrogenation reaction steps and products were identified. - Abstract: Dehydrogenation behavior of LiAlH4–MgH2 composites was investigated by using thermal gravimetric analysis (TGA) and in situ synchrotron X-ray diffraction (XRD) technique. The experimental results showed that MgH2 could play a catalytic role in lowing the initial dehydrogenation temperature of LiAlH4. Besides, MgH2 could be destabilized by the dehydrogenation reaction products of LiAlH4. The initial dehydrogenation temperature of LiAlH4–MgH2 composites was as low as 145 °C and MgH2 could decompose below 300 °C. The compounds such as LiMgAlH6, Al3Mg2, Al12Mg17 and Li0.92Mg4.08 formed during dehydrogenation process suggested some mutual reactions proceeded between LiAlH4 and MgH2

  13. Spontaneous dehydrogenation of methanol over defect-free MgO(100) thin film deposited on molybdenum

    CERN Document Server

    Song, Zhenjun

    2016-01-01

    The dehydrogenation reaction of methanol on metal supported MgO(100) films has been studied by employing periodic density functional calculations. As far as we know, the dehydrogenation of single methanol molecule over inert oxide insulators such as MgO has never been realized before without the introduction of defects and low coordinated atoms. By depositing the very thin oxide films on Mo substrate we have successfully obtained the dissociative state of methanol. The dehydrogenation reaction is energetically exothermic and nearly barrierless. The metal supported thin oxide films studied here provide a versatile approach to enhance the activity and properties of oxides.

  14. Acid Separation, Catalytic Oxidation and Coagulation for ATC Waste Liquid Treatment

    Institute of Scientific and Technical Information of China (English)

    DING Xiaoling; JIA Chunning

    2005-01-01

    It is difficult to treat 2-amino-thiazoline-4-carboxylic acid (ATC) waste liquid effectively at present for its characteristics of high chemical oxygen demand (COD), high salinity and low biodegradability. In order to solve this problem, this paper presents several kinds of physical-chemical treatment unit techniques, including acid separation, catalytic oxidation and coagulation. First of all, acid separation was adopted to precipitate relevant organics at isoelectric point. When the temperature and pH value of acid separation were controlled at about 5 ℃ and 2.2 respectively, the COD removal rate could reach 27.6%. Secondly, oxidation was used to break chemical constitution of refractory organics. The optimal reaction parameters of catalytic oxidation should be 20 ℃, pH adjusted to 5.0 and [Fe2+] 300 mg/L. Then with 5% H 2O 2 added and after one-hour reaction, the COD removal rate could achieve about 52%. Finally, coagulation was adopted to remove a portion of refractory organics, and 15% polymeric molysite flocculant was the best for the coagulation, and the COD removal rate could reach about 15%. Therefore, the proposed feasible process of physical-chemical pretreatment for ATC waste liquid could have about 70% COD removed in total.

  15. Catalytic partial oxidation of methane over porous silica supported VO{sub x} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pirovano, C.; Schoenborn, E.; Kalevaru, V.N.; Wohlrab, S.; Luecke, B.; Martin, A. [University Rostock e.V., Rostock (Germany). Leibniz Inst. for Catalysis

    2011-07-01

    High surface area mesoporous siliceous MCM-41 and SBA-15 materials have been used as supports to disperse vanadium oxide species using wet impregnation and incipient wetness impregnation methods. These materials were used as catalysts for the partial oxidation of methane (POM) to formaldehyde. The physico-chemical properties of the solids were studied by means of BET, DR-UV/Vis spectroscopy, Py-FTIR and TEM. The influence of support and the preparation method on the dispersion of VOx is also investigated. The catalytic properties of the catalysts were examined in a fixed bed stainless steel reactor at 923 K. So far a maximum production of formaldehyde can be detected on SBA-15 supported VOx-catalysts prepared by incipient wetness impregnation. On this V/SBA-15 material a covalent attachment of catalytic active molecular vanadium species dominates, which in turn leads to a lower activation temperature and thereby reduced over-oxidation. From the best case, the space time yield of HCHO could be reached close to 775 g{sub HCHO} Kg{sub cat}{sup -1} h{sup -1}. (orig.)

  16. Catalytic Role of Manganese Oxides in Prebiotic Nucleobases Synthesis from Formamide

    Science.gov (United States)

    Bhushan, Brij; Nayak, Arunima; Kamaluddin

    2016-06-01

    Origin of life processes might have begun with the formation of important biomonomers, such as amino acids and nucleotides, from simple molecules present in the prebiotic environment and their subsequent condensation to biopolymers. While studying the prebiotic synthesis of naturally occurring purine and pyrimidine derivatives from formamide, the manganese oxides demonstrated not only good binding for formamide but demonstrated novel catalytic activity. A novel one pot manganese oxide catalyzed synthesis of pyrimidine nucleobases like thymine is reported along with the formation of other nucleobases like purine, 9-(hydroxyacetyl) purine, cytosine, 4(3 H)-pyrimidinone and adenine in acceptable amounts. The work reported is significant in the sense that the synthesis of thymine has exhibited difficulties especially under one pot conditions and also such has been reported only under the catalytic activity of TiO2. The lower oxides of manganese were reported to show higher potential as catalysts and their existence were favored by the reducing atmospheric conditions prevalent on early Earth; thereby confirming the hypothesis that mineral having metals in reduced form might have been more active during the course of chemical evolution. Our results further confirm the role of formamide as a probable precursor for the formation of purine and pyrimidine bases during the course of chemical evolution and origin of life.

  17. Catalytic Role of Manganese Oxides in Prebiotic Nucleobases Synthesis from Formamide.

    Science.gov (United States)

    Bhushan, Brij; Nayak, Arunima; Kamaluddin

    2016-06-01

    Origin of life processes might have begun with the formation of important biomonomers, such as amino acids and nucleotides, from simple molecules present in the prebiotic environment and their subsequent condensation to biopolymers. While studying the prebiotic synthesis of naturally occurring purine and pyrimidine derivatives from formamide, the manganese oxides demonstrated not only good binding for formamide but demonstrated novel catalytic activity. A novel one pot manganese oxide catalyzed synthesis of pyrimidine nucleobases like thymine is reported along with the formation of other nucleobases like purine, 9-(hydroxyacetyl) purine, cytosine, 4(3 H)-pyrimidinone and adenine in acceptable amounts. The work reported is significant in the sense that the synthesis of thymine has exhibited difficulties especially under one pot conditions and also such has been reported only under the catalytic activity of TiO2. The lower oxides of manganese were reported to show higher potential as catalysts and their existence were favored by the reducing atmospheric conditions prevalent on early Earth; thereby confirming the hypothesis that mineral having metals in reduced form might have been more active during the course of chemical evolution. Our results further confirm the role of formamide as a probable precursor for the formation of purine and pyrimidine bases during the course of chemical evolution and origin of life. PMID:26758444

  18. Catalytic oxidation of 4-tert-butyltoluene over Ti-MCM-41

    Institute of Scientific and Technical Information of China (English)

    Wei Hua Yu; Chun Hui Zhou; Xiang Sheng Xu; Zhong Hua Ge

    2007-01-01

    The surface-grafted titanium MCM-41 materials were prepared by anchoring titanocene onto the inner walls of MCM-41. The materials were characterized by powder X-ray diffraction (XRD), N2 adsorption-desorption isotherm and diffuse reflectance UV-visible (UV-vis) spectroscopies. The catalytic properties of Ti-MCM-41 were tested in oxidation of 4-tert-butyltoluene with tert-butylhydroperoxide (TBHP) in liquid phase. MCM-41 with loading 4.8 mol% Ti gave the maximal conversions of 23.6% of 4-tert-butyltoluene with a complete selectivity to 4-tert-butylbenzaldehyde.

  19. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  20. MWW-type titanosilicate synthesis, structural modification and catalytic applications to green oxidations

    CERN Document Server

    Wu, Peng; Xu, Le; Liu, Yueming; He, Mingyuan

    2013-01-01

    This book provides a comprehensive review of a new generation of selective oxidation titanosilicate catalysts with the MWW topology (Ti-MWW) based on the research achievements of the past 12 years. It gives an overview of the synthesis, structure modification and catalytic properties of Ti-MWW. Ti-MWW can readily be prepared by means of direct hydrothermal synthesis with crystallization-supporting agents, using dual-structure-directing agents and a dry-gel conversion technique. It also can be post-synthesized through unique reversible structure transformation and liquid-phase isomorphous subst

  1. Catalytic aerobic oxidation and tandem enantioselective cycloaddition in cascade multicomponent synthesis.

    Science.gov (United States)

    Potowski, Marco; Merten, Christian; Antonchick, Andrey P; Waldmann, Herbert

    2015-03-23

    An efficient multicomponent cascade transformation for the highly diastereo- and enantioselective synthesis of complex natural product inspired polycyclic products from simple starting materials is described. The cascade is initiated by copper-catalyzed aerobic CH oxidation of cyclopentadiene to cyclopentadienone followed by double catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides. The cascade synthesis efficiently yields structurally complex 5,5,5-tricyclic products with eight stereocenters with good yields and excellent diastereo- and enantiocontrol using one catalyst. PMID:25676025

  2. Possible nature of the catalytic activity of metalloporphyrins in reactions to nonchain oxidation of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Solov' eva, A.B.; Karakozova, E.I.; Karmilova, L.V.; Timashev, S.F.

    1985-05-01

    The authors hypothesize that an intermediate cyclic complex, TPPMn(II) with oxygen and the olefin, is formed during the catalytic oxidation of olefins with a varying degree of substitution in the double bond of the system: molecular oxygen-TPP MnCl-NaBH/sub 4/ (TPP: tetraphenylporphyrin). They hypothesize that strong electrical fields in the submicrovicinity of the metalloporphyrin (MP) molecule favor the formation of a cyclic intermediate complex. They conclude that the possibility of the formation of a cyclic intermediate complex is verified on the basis of data on the state of the central reduced ion and the type of coordination of the oxygen molecule.

  3. Rare earth oxide aero- and xerogels. Tuning porosity and catalytic properties

    International Nuclear Information System (INIS)

    Heterogeneous catalysts to this day are still largely developed on the basis of trial and error. This is due to the great difficulty of creating custom-designed structures at the nanometer scale using traditional preparation methods. In the course of recent rapid developments in the material sciences, however, it has become possible to create materials with custom-designed properties from the macroscopic down into the nanometer range. The purpose of the present study was to make use of this potential for catalysis. The task was to modify the porosity and composition of selected rare earth oxides that promise well as catalysts with the goal of obtaining good results in terms of oxidative reactions and oxidative coupling. One major focus was on chemical sol-gel methods and in particular on what is referred to as the epoxide addition method. Extensive work was put into the characterisation and catalytic testing of aerogels and xerogels of pure rare earth oxides as well as of hybrid systems of rare earth oxides and aluminium oxide. Furthermore, thin xerogel films and macroporous monoliths were produced, the latter using a direct foaming method. The results of this work confirm the high potential of sol-gel chemistry for making porous materials of variable and controllable porosity and composition available for heterogeneous catalysis and creating more powerful catalysts.

  4. Chloride ions promoted the catalytic wet peroxide oxidation of phenol over clay-based catalysts.

    Science.gov (United States)

    Zhou, Shiwei; Zhang, Changbo; Xu, Rui; Gu, Chuantao; Song, Zhengguo; Xu, Minggang

    2016-01-01

    Catalytic wet peroxide oxidation (CWPO) of phenol over clay-based catalysts in the presence and absence of NaCl was investigated. Changes in the H2O2, Cl(-), and dissolved metal ion concentration, as well as solution pH during phenol oxidation, were also studied. Additionally, the intermediates formed during phenol oxidation were detected by liquid chromatography-mass spectroscopy and the chemical bonding information of the catalyst surfaces was analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that the presence of Cl(-) increased the oxidation rate of phenol to 155%, and this phenomenon was ubiquitous during the oxidation of phenolic compounds by H2O2 over clay-based catalysts. Cl(-)-assisted oxidation of phenol was evidenced by several analytical techniques such as mass spectroscopy (MS) and XPS, and it was hypothesized that the rate-limiting step was accelerated in the presence of Cl(-). Based on the results of this study, the CWPO technology appears to be promising for applications in actual saline phenolic wastewater treatment. PMID:26942523

  5. Synthesis, characterization, and catalytic application of ordered mesoporous carbon–niobium oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Juan-Li; Gao, Shuang; Liu, Chun-Ling; Liu, Zhao-Tie; Dong, Wen-Sheng, E-mail: wsdong@snnu.edu.cn

    2014-11-15

    Graphical abstract: The ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process. - Highlights: • Ordered mesoporous carbon–niobium oxide composites were synthesized. • The content of Nb{sub 2}O{sub 5} in the composites could be tuned from 38 to 75%. • Niobium species were highly dispersed in amorphous carbon framework walls. • The composites exhibited good catalytic performance in the dehydration of fructose. - Abstract: Ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process using phenolic resol as carbon source, niobium chloride as precursor and amphiphilic triblock copolymer Pluronic F127 as template. The resulting materials were characterized using a combination of techniques including differential scanning calorimetry–thermogravimetric analysis, N{sub 2} physical adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show that with increasing the content of Nb{sub 2}O{sub 5} from 38 to 75% the specific surface area decreases from 306.4 to 124.5 m{sup 2} g{sup −1}, while the ordered mesoporous structure is remained. Niobium species is well dispersed in the amorphous carbon framework. The mesoporous carbon–niobium oxide composites exhibit high catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural. A 100% conversion of fructose and a 76.5% selectivity of 5-hydroxymethylfurfural were obtained over the carbon–niobium oxide composite containing 75% Nb{sub 2}O{sub 5} under the investigated reaction conditions.

  6. Oscillations, period doublings, and chaos in CO oxidation and catalytic mufflers.

    Science.gov (United States)

    Marek, Milos; Schejbal, Matyás; Kocí, Petr; Nevoral, Vladislav; Kubícek, Milan; Hadac, Otto; Schreiber, Igor

    2006-09-01

    Early experimental observations of chaotic behavior arising via the period-doubling route for the CO catalytic oxidation both on Pt(110) and Ptgamma-Al(2)O(3) porous catalyst were reported more than 15 years ago. Recently, a detailed kinetic reaction scheme including over 20 reaction steps was proposed for the catalytic CO oxidation, NO(x) reduction, and hydrocarbon oxidation taking place in a three-way catalyst (TWC) converter, the most common reactor for detoxification of automobile exhaust gases. This reactor is typically operated with periodic variation of inlet oxygen concentration. For an unforced lumped model, we report results of the stoichiometric network analysis of a CO reaction subnetwork determining feedback loops, which cause the oscillations within certain regions of parameters in bifurcation diagrams constructed by numerical continuation techniques. For a forced system, numerical simulations of the CO oxidation reveal the existence of a period-doubling route to chaos. The dependence of the rotation number on the amplitude and period of forcing shows a typical bifurcation structure of Arnold tongues ordered according to Farey sequences, and positive Lyapunov exponents for sufficiently large forcing amplitudes indicate the presence of chaotic dynamics. Multiple periodic and aperiodic time courses of outlet concentrations were also found in simulations using the lumped model with the full TWC kinetics. Numerical solutions of the distributed model in two geometric coordinates with the CO oxidation subnetwork consisting of several tens of nonlinear partial differential equations show oscillations of the outlet reactor concentrations and, in the presence of forcing, multiple periodic and aperiodic oscillations. Spatiotemporal concentration patterns illustrate the complexity of processes within the reactor. PMID:17014241

  7. Facile synthesis of magnetically separable reduced graphene oxide/magnetite/silver nanocomposites with enhanced catalytic activity.

    Science.gov (United States)

    Ji, Zhenyuan; Shen, Xiaoping; Yue, Xiaoyang; Zhou, Hu; Yang, Juan; Wang, Yuqin; Ma, Lianbo; Chen, Kangmin

    2015-12-01

    In this study, the combination of magnetite (Fe3O4) with reduced graphene oxide (RGO) generates a new hybrid substrate for the dispersion of noble metal nanoparticles. Well-dispersed silver (Ag) nanoparticles loaded on the surface of Fe3O4 modified RGO are achieved by an efficient two-step approach. Through reducing Ag(+) ions, highly dispersed Ag nanoparticles are in-situ formed on the RGO/Fe3O4 substrate. It is found that the existence of Fe3O4 nanocrystals can significantly improve the dispersity and decrease the particle size of the in-situ formed Ag nanoparticles. Magnetic study reveals that the as-prepared RGO/Fe3O4/Ag ternary nanocomposites display room-temperature superparamagnetic behavior. The catalytic properties of the RGO/Fe3O4/Ag ternary nanocomposites were evaluated with the reduction of 4-nitrophenol into 4-aminophenol as a model reaction. The as-synthesized RGO/Fe3O4/Ag ternary catalysts exhibit excellent catalytic stability and much higher catalytic activity than the corresponding RGO/Ag catalyst. Moreover, the RGO/Fe3O4/Ag catalysts can be easily magnetically separated for reuse. This study further demonstrates that nanoparticles modified graphene can act as an effective hybrid substrate for the synthesis of multi-component and multifunctional graphene-based composites. PMID:26263498

  8. Radiation influencing of catalytic activity and reactivity of selected mixed oxides

    International Nuclear Information System (INIS)

    Two mixed oxides, viz. CuO-Bi2O3 and NiO-Bi2O3, of various compositions were studied with respect to their physico-chemical properties, catalytic activity, and chemical reactivity, using hydrogen peroxide decomposition and hydrogen reduction as the test reactions. Pre-irradiation of the CuO-Bi2O3 catalyst with 60Co gamma rays (0.5, 1.0, 1.5, or 3.0 MGy) and accelerated electrons (4 MeV) brought about changes in the mutual influence of the system components accompanied by formation of induced catalytic sites. The reduction rate decrease in the two side regions after electron irradiation and after gamma irradiation applying the extremely high dose of 3 MGy can be correlated with the increase in the concentration of the strongly bonded oxygen forms, giving rise to centres for donor hydrogen chemisorption. The NiO-Bi2O3 system seems to be less stable than the CuO-Bi2O3 system. Gamma irradiation (1 MGy) in water brought about decrease in the catalytic activity but no change in the mutual influence of the two components of the system. In the same conditions the reduction rate decreased appreciably, whereas pre-irradiation in air led to acceleration of the reduction process. This can be ascribed to a higher concentration of the stabilized charge defects, enhancing the reactivity of the interface. (author). 4 figs., 6 refs

  9. Photo catalytic Oxidation of Carbon Monoxide over NiO/SnO2 Nano composites under UV Irradiation

    International Nuclear Information System (INIS)

    The NiO/SnO2 nano composites have been prepared by the simple coprecipitation method and further characterized by the XRD, SEM, TEM, UV-Vis, and BET. X-ray diffraction (XRD) data analyses indicate the exclusive formation of nano sized particles with rutile-type phase (tetragonal SnO2) for Ni contents below 10 mol%. Only above 10 mol% Ni, the formation of a second NiO-related phase has been determined. The particle size is in the range from 12 to 6 nm. It decreases with increasing amounts of doping NiO. The morphology of NiO-doped SnO2 nanocrystalline powders is spherical, and the distribution of particle size is uniform, as seen from transmission electron microscopy (TEM). The photo catalytic oxidation of CO over NiO/SnO2 photo catalyst has been investigated under UV irradiation. Effects of NiO loading on SnO2, photo catalyst loading, and reaction time on photo catalytic oxidation of CO have been systematically studied. Compared with pure SnO2, the 33.3 mol% NiO/SnO2 composite exhibited approximately twenty fold enhancement of photo catalytic oxidation of CO. Our results provide a method for pollutants removal. Due to simple preparation, high photo catalytic oxidation of CO, and low cost, the NiO/SnO2 photo catalyst will find wide application in the coming future of photo catalytic oxidation of CO

  10. Catalytic wet oxidation of ammonia solution: Activity of the nanoscale platinum-palladium-rhodium composite oxide catalyst

    International Nuclear Information System (INIS)

    Aqueous solutions of 400-1000 mg/L of ammonia were oxidized in a trickle-bed reactor (TBR) in this study of nanoscale platinum-palladium-rhodium composite oxide catalysts, which were prepared by the co-precipitation of H2PtCl6, Pd(NO3)3 and Rh(NO3)3. Hardly any of the dissolved ammonia was removed by wet oxidation in the absence of any catalyst, whereas about 99% of the ammonia was reduced during wet oxidation over nanoscale platinum-palladium-rhodium composite oxide catalysts at 503 K in an oxygen partial pressure of 2.0 MPa. A synergistic effect exists in the nanoscale platinum-palladium-rhodium composite structure, which is the material with the highest ammonia reduction activity. The nanometer-sized particles were characterized by TEM, XRD and FTIR. The effect of the initial concentration and reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid hourly space velocity of under 9 h-1 in the wet catalytic processes

  11. Catalytic incineration of CO and VOC emissions over supported metal oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Per-Olof

    1999-05-01

    Catalytic incineration is one of the methods to reduce the emissions of CO and VOCs. Low operation temperature and low catalyst cost are essential parameters for catalytic incinerators. Pt/Al{sub 2}O{sub 3} catalysts are frequently used today, but the cheaper metal oxide catalysts can be very competitive if comparable overall activity is obtained. This thesis concerns how it is possible to decrease the operation temperature for supported metal oxide catalysts by using different supports, active metal oxides and additives. In the thesis it is demonstrated that different copper oxide based catalysts have the best activity and durability for complete oxidation among several tested metal oxide catalysts. CuO{sub x} supported on TiO{sub 2} and Al{sub 2}O{sub 3} showed increased activity with the CuO{sub x} loading up to the threshold coverage for formation of crystalline CuO particles, which is 12 {mu}mol/m{sup 2} on TiO{sub 2} and 6 {mu}mol/m{sup 2} on Al{sub 2}O{sub 3}. Up to the threshold coverage for CuO formation, well dispersed copper oxide species were formed on TiO{sub 2}, and a dispersed copper aluminate surface phase was formed on Al{sub 2}O{sub 3}. Durability tests showed accelerated sintering of TiO{sub 2} by copper, but stabilisation was possible by modification of the TiO{sub 2} with CeO{sub x} before the deposition of CuO{sub x}. The stabilisation was obtained by formation of a Ce-O-Ti surface phase. Addition of CeO{sub x} also enhanced the activity of the copper oxide species thanks to favourable interaction between the active copper oxide species and the CeO{sub x} on the support, which could be seen as increased reducibility in TPR experiments. The increased activity and reducibility was also observed for CuO{sub x} supported on ceria modified Al{sub 2}O{sub 3}. In this regard it was shown that CuO{sub x} deposited on CeO{sub 2}(001) surfaces was substantially more active for CO oxidation than copper oxide deposited on CeO{sub 2}(111) Surfaces. This

  12. Graphene oxide reduced and modified by environmentally friendly glycylglycine and its excellent catalytic performance

    International Nuclear Information System (INIS)

    An environmentally friendly new approach to prepare reduced graphene oxide (RGO) was developed by using glycylglycine (gly-gly) as both a reducing and stabilizing agent. Graphene oxide (GO) was transformed to RGO with the appropriate pH, temperature and reducing agent/GO ratio. The RGO was characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermo-gravimetric analysis, x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy. The RGO aqueous suspension showed extraordinary stability in the absence of any external stabilizing reagents. The XPS analysis showed that this excellent stability is due to modifications of the RGO nanosheets by the gly-gly molecules. The modified RGO complex with copper shows good catalytic performance for reduction of 4-nitrophenol to 4-aminophenol. (paper)

  13. Graphene oxide reduced and modified by environmentally friendly glycylglycine and its excellent catalytic performance

    Science.gov (United States)

    Zhang, Congcong; Chen, Mingxi; Xu, Xiaoyang; Zhang, Li; Zhang, Lei; Xia, Fengling; Li, Xichuan; Liu, Yu; Hu, Wenping; Gao, Jianping

    2014-04-01

    An environmentally friendly new approach to prepare reduced graphene oxide (RGO) was developed by using glycylglycine (gly-gly) as both a reducing and stabilizing agent. Graphene oxide (GO) was transformed to RGO with the appropriate pH, temperature and reducing agent/GO ratio. The RGO was characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermo-gravimetric analysis, x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy. The RGO aqueous suspension showed extraordinary stability in the absence of any external stabilizing reagents. The XPS analysis showed that this excellent stability is due to modifications of the RGO nanosheets by the gly-gly molecules. The modified RGO complex with copper shows good catalytic performance for reduction of 4-nitrophenol to 4-aminophenol.

  14. Electro-catalytic oxidation of phenol with Ti-base lead dioxide electrode

    Institute of Scientific and Technical Information of China (English)

    王东田; 魏杰; 于秀娟; 杨红

    2003-01-01

    The Ti-base PbO2 electrode prepared by electrodeposition of PbO2 on the surface of titanium was used for electro-catalytic oxidation of phenol in waste water. The experimental results show that the electrodeposition of PbO2 at a higher current density for a short time, then followed by a lower current density can get a compact and combinative PbO2 layer. The properties of a Ti/PbO2 electrode with an interlayer of oxide are the best. When this kind of electrode is used to treat phenol containing waste water, the phenol-removal rate is higher and the slot voltage is lower. In addition, by using the phenol-removal rate as an index, the influences of electrolysis current density, mass transfer condition and pH were studied and the optimal condition was confirmed.

  15. Development of the Monolith Froth Reactor for Catalytic Wet Oxidation of CELSS Model Wastes

    Science.gov (United States)

    Abraham, Martin; Fisher, John W.

    1995-01-01

    The aqueous phase oxidation of acetic acid, used as a model compound for the treatment of CELSS (Controlled Ecological Life Support System) waste, was carried out in the monolith froth reactor which utilizes two-phase flow in the monolith channels. The catalytic oxidation of acetic acid was carried out over a Pt/Al2O3 catalyst, prepared at The University of Tulsa, at temperatures and pressures below the critical point of water. The effect of externally controllable parameters (temperature, liquid flow rate, distributor plate orifice size, pitch, and catalyst distance from the distributor plate) on the rate of acetic acid oxidation was investigated. Results indicate reaction rate increased with increasing temperature and exhibited a maximum with respect to liquid flow rate. The apparent activation energy calculated from reaction rate data was 99.7 kJ/mol. This value is similar to values reported for the oxidation of acetic acid in other systems and is comparable to intrinsic values calculated for oxidation reactions. The kinetic data were modeled using simple power law kinetics. The effect of "froth" feed system characteristics was also investigated. Results indicate that the reaction rate exhibits a maximum with respect to distributor plate orifice size, pitch, and catalyst distance from the distributor plate. Fundamental results obtained were used to extrapolate where the complete removal of acetic acid would be obtained and for the design and operation of a full scale CELSS treatment system.

  16. Tuning size and catalytic activity of nano-clusters of cobalt oxide

    Indian Academy of Sciences (India)

    R Venkat Narayan; Vinod Kanniah; Aruna Dhathathreyan

    2006-03-01

    Cobalt oxides were prepared by three different methods: (1) by reacting cobalt nitrate with oxalic acid, (2) co-precipitating cobalt nitrate with sodium carbonate, and (3) using sodium dodecyl sulphate as organic surfactant. All three samples were characterized before and after calcination by solvent extraction and the resulting products examined by IR spectroscopy. In the case of method 3, the removal of surfactant was followed by TGA studies. Products from all three methods were identified by XRD. Peaks in low angle XRD indicate the porous nature of the oxides. The morphology of the pores was studied by transmission electron microscopy. Some irregular pore structures were obtained for samples from methods 1 and 2, with an average size of 4-6 nm. Only the product from method 3 using SDS as template showed ordered structure and optimum size, and Brunauer-Emmet-Teller surface areas of the as-prepared, as well as the treated samples, exhibited H3 type hysteresis. The samples from the three methods were used as catalysts in the oxidation reaction of cyclohexane under mild conditions and the catalytic efficiency of the cobalt oxide was comparable with mesoporous cobalt oxides.

  17. Synthesis and characterization of conventional and mesoporous Ga-MFI for ethane dehydrogenation

    DEFF Research Database (Denmark)

    Leth, Karen Thrane; Rovik, Anne Krogh; Holm, Martin Spangsberg;

    2008-01-01

    difference being the morphology of the crystals. The catalytic properties of the samples were tested in ethane dehydrogenation at 823 K and at atmospheric pressure. The two Ga-MFI samples differ greatly in conversion of ethane, as a result of their difference in porosity, and it is found that the conversion...

  18. Amino olefin nickel(I) and nickel(0) complexes as dehydrogenation catalysts for amine boranes

    NARCIS (Netherlands)

    M. Vogt; B. de Bruin; H. Berke; M. Trincado; H. Grützmacher

    2011-01-01

    A rare paramagnetic organometallic nickel(I) olefin complex can be isolated using the ligand bis(5H-dibenzo[a,d]cyclohepten-5-yl)amine. This complex and related nickel(0) hydride complexes show very high catalytic activity in the dehydrogenation of dimethylamino borane with release of one equivalent

  19. Effects of Gas Velocity and Temperature on Nitric Oxide Conversion in Simulated Catalytic Converter

    Directory of Open Access Journals (Sweden)

    Sathaporn Chuepeng

    2012-01-01

    Full Text Available Problem statement: Gaseous emissions from gasoline engine such as carbon monoxide, unburned hydrocarbon and nitrogen oxides were usually reduced in three-way catalytic converter simultaneously around theoretical fuel and air combustion. Engine speed and load and other parameters were varied over a wide range of operating conditions, resulting in different exhaust gas composition and condition intake into catalytic converter. This work was studied the conversion of Nitric Oxide (NO in exhaust gas catalytic converter affected by gas velocity and inlet temperature using numerical modeling. Approach: The simulation was based on a one-dimensional time-dependent model within a single monolith channel of the converter. Upon certain assumptions, the study was considered heterogeneous combustion reaction between gas and solid phases based on lumped kinetic reactions. In this study, constants and variables used for mass and heat transfers were dependent on gas or solid phase temperature and mole fraction. Finite difference scheme incorporated with the generated computer code was established for solving species and energy balances within gas and solid phases. Results: The NO conversion was increased with transient period in initial and reached steady state at different values. The lower inlet gas temperature was resulted in lesser NO conversion at the same inlet NO concentration and gas velocity. The light-off temperatures were up to 520 K and a sudden rise in NO conversion was from 550-605 K and decreasing onwards, generating working temperature window. NO conversion increased throughout the catalyst bed from the inlet and the conversion decreased as the gas velocity increased. Conclusion/Recommendations: Gas space velocity and gas temperature intake to the converter affected the NO conversion over the time and the axial distance from the catalyst bed inlet. The numerical results have summarily demonstrated a good approximation compared to experimental

  20. Preparation and catalytic properties of honeycomb catalyst for hydrogen isotope oxidation

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Honeycomb catalysts with good physical properties were prepared for detritiation. • The catalysts increase gas flow rate significantly without decreasing the conversion rate. • The catalysts were used at room temperature with high H2 conversion rate. • The confines of H2 concentration and flow rate for catalyst application were tested. - Abstract: The method of catalytic oxidation and adsorption is widely used for atmosphere detritiation. But traditional particle catalyst has large gas resistance, which limited the space velocity for detritiation. Honeycomb catalyst can enormously increase the gas handling capacity due to its low pressure drop and high dispersity of active ingredients, but has not been used in detritiation so far. A coating of alumina was deposited on the honeycomb substrate of cordierite using ultrasonic technology. By the method of excessive impregnating, noble metal (Pt or Pd) supported catalysts were prepared. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption/desorption (Brunauer–Emmet–Teller – BET method), scanning electron microscope (SEM) and laser particles sizer. The result shows that the alumina coatings are well distributed, well knitted and the specific surface area of honeycomb catalyst rises to about 20 m2/g. Catalytic activities were evaluated by H2 conversion rate in gas mixture (with different H2 concentration and various flow rates). The results indicated that all catalysts exhibited excellent catalytic performance for H2 oxidation; the conversions of hydrogen were 100% at room temperature when the gas space velocity was up to 6 × 105 h−1

  1. A Novel Supramolecular Assembly Film of Porphyrin Bound DNA: Characterization and Catalytic Behaviors Towards Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Osamu Ikeda

    2005-04-01

    Full Text Available A stable Fe(4-TMPyP-DNA-PADDA (FePyDP film was characterized onpyrolytic graphite electrode (PGE or an indium-tin oxide (ITO electrode through thesupramolecular interaction between water-soluble iron porphyrin (Fe(4-TMPyP and DNAtemplate, where PADDA (poly(acrylamide-co-diallyldimethylammonium chloride isemployed as a co-immobilizing polymer. Cyclic voltammetry of FePyDP film showed a pairof reversible FeIII/FeII redox peaks and an irreversible FeIV/FeIII peak at –0.13 V and 0.89vs. Ag|AgCl in pH 7.4 PBS, respectively. An excellent catalytic reduction of NO wasdisplayed at –0.61 V vs. Ag|AgCl at a FePyDP film modified electrode.Chronoamperometric experiments demonstrated a rapid response to the reduction of NOwith a linear range from 0.1 to 90 μM and a detection limit of 30 nM at a signal-to-noiseratio of 3. On the other hand, it is the first time to apply high-valent iron porphyrin ascatalyst at modified electrode for NO catalytic oxidation at 0.89 vs. Ag|AgCl. The sensorshows a high selectivity of some endogenous electroactive substances in biological systems.The mechanism of response of the sensors to NO is preliminary studied.

  2. Solid-oxide fuel cell operated on in situ catalytic decomposition products of liquid hydrazine

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Hongxia; Ran, Ran; Zhou, Wei; Shao, Zongping; Jin, Wanqin; Xu, Nanping [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, No. 5 Xing Mofan Road, Nanjing, JiangSu 210009 (China); Ahn, Jeongmin [School of Mechanical and Materials Engineering, Washington State University, Sloan 217, Pullman, WA 99164-2920 (United States)

    2008-03-01

    Hydrazine was examined as a fuel for a solid-oxide fuel cell (SOFC) that employed a typical nickel-based anode. An in situ catalytic decomposition of hydrazine at liquid state under room temperature and ambient pressure before introducing to the fuel cell was developed by applying a Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF) oxide catalyst. Catalytic testing demonstrated that liquid N{sub 2}H{sub 4} can be decomposed to gaseous NH{sub 3} and H{sub 2} at a favorable rate and at a temperature as low as 20 C and H{sub 2} selectivity reaching values as high as 10% at 60 C. Comparable fuel cell performance was observed using either the in situ decomposition products of hydrazine or pure hydrogen as fuel. A peak power density of {proportional_to}850 mW cm{sup -2} at 900 C was obtained with a typical fuel cell composed of scandia-stabilized zirconia and La{sub 0.8}Sr{sub 0.2}MnO{sub 3} cathode. The high energy and power density, easy storage and simplicity in fuel delivery make it highly attractive for portable applications. (author)

  3. Activated carbon and tungsten oxide supported on activated carbon catalysts for toluene catalytic combustion.

    Science.gov (United States)

    Alvarez-Merino, M A; Ribeiro, M F; Silva, J M; Carrasco-Marín, F; Maldonado-Hódar, F J

    2004-09-01

    We have used activated carbon (AC) prepared from almond shells as a support for tungsten oxide to develop a series of WOx/AC catalysts for the catalytic combustion of toluene. We conducted the reaction between 300 and 350 degrees C, using a flow of 500 ppm of toluene in air and space velocity (GHSV) in the range 4000-7000 h(-1). Results show that AC used as a support is an appropriate material for removing toluene from dilute streams. By decreasing the GHSV and increasing the reaction temperature AC becomes a specific catalyst for the total toluene oxidation (SCO2 = 100%), but in less favorable conditions CO appears as reaction product and toluene-derivative compounds are retained inside the pores. WOx/AC catalysts are more selective to CO2 than AC due to the strong acidity of this oxide; this behavior improves with increased metal loading and reaction temperature and contact time. The catalytic performance depends on the nonstoichiometric tungsten oxide obtained during the pretreatment. In comparison with other supports the WOx/AC catalysts present, at low reaction temperatures, higher activity and selectivity than WO, supported on SiO2, TiO2, Al2O3, or Y zeolite. This is due to the hydrophobic character of the AC surface which prevents the adsorption of water produced from toluene combustion thus avoiding the deactivation of the active centers. However, the use of WOx/AC system is always restricted by its gasification temperature (around 400 degrees C), which limits the ability to increase the conversion values by increasing reaction temperatures. PMID:15461177

  4. Heterogeneous selective oxidation of formaldehyde over oxide catalysts. 1. Catalytic properties of H3PMo12O40 and K3PMoO12O40

    International Nuclear Information System (INIS)

    Catalytic properties of H3PMo12O40 and K3PMo12O40, dried at 120 deg C and calcinated at 420 deg C, were investigated in the reaction of heterogenous oxidation of formaldehyde in temperature range 120-180 deg C. It is shown that catalytic properties are determined by heat treatment conditions. Formic acid is the main product of formaldehyde oxidation on dried samples. Samples calcinated at 42 deg C are inactive in reaction of formaldehyde oxidation. It is shown that hydrated forms of H3PMo12O40 and K3PMo12O40 are effective in this reaction. (author)

  5. Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Ankur Bordoloi

    2014-01-01

    Full Text Available Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15 wt% and calcination temperatures of 673, 973, and 1073 K indicates that Co2+ is homogeneously distributed in the mesoporous alumina matrix. As a function of the Co loading, different phases are present comprising poorly crystalline alumina and mixed cobalt aluminum oxides of the spinel type. The mixed cobalt-aluminum oxides were applied as catalysts in CO oxidation and turned out to be highly active.

  6. Synthesis, characterization and photo catalytic studies of the composites by tantalum oxide and zinc oxide nanorods

    Science.gov (United States)

    Chennakesavulu, K.; Reddy, M. Madhusudhana; Reddy, G. Ramanjaneya; Rabel, A. M.; Brijitta, J.; Vinita, V.; Sasipraba, T.; Sreeramulu, J.

    2015-07-01

    In-situ synthesis of ZnO:Ta2O5 composites in basic medium by using tantalum chloride and zinc chloride as precursors. The prepared composites were characterized by Fourier Transform Infrared spectroscopy (FTIR), confocal Raman spectroscopy, diffuse reflectance UV-Vis spectrophotometer (DRS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, N2-sorption isotherms, Thermo Gravimetric Analysis (TGA), High Resolution Transmission Electron Microscope (HRTEM), X-ray Photoelectron Spectroscopy (XPS), and Field Emission Scanning Electron Microscopy (FESEM/EDS). The composite materials were used as photocatalyst in the degradation Rhodamine-B (RhB) dye under visible light irradiation. The catalytic activity and removal percentage of the dye was determined by the spectrophotometric method. This indicates the percentage of degradation was more for the ZnO:Ta2O5 composites. The kinetic parameter obeys pseudo-first order reaction. It may be due to fixed amount the catalysts and concentration of dye solution. The catalytic activity of the recycled ZnO:Ta2O5 catalyst was compared with fresh catalyst.

  7. Influence of thermal treatments on the basic and catalytic properties of Mg,Al-mixed oxides derived from hydrotalcites

    Directory of Open Access Journals (Sweden)

    R. Bastiani

    2004-06-01

    Full Text Available This work studied the influence of calcination conditions on basic properties and catalytic performance of Mg,Al-mixed oxides derived from a hydrotalcite sample (Al/(Al+Mg=0.20. Various heating rates, calcination atmospheres and lengths of calcination at 723K were evaluated. TPD of CO2 and retroaldolization of diacetone alcohol (DAA were used to determine the basic properties of the mixed oxides. The basic site density determined by TPD of CO2 showed a better correlation with catalytic activity for acetone/citral aldol condensation than the relative basicity obtained from retroaldolization of DAA. Calcination atmosphere was the parameter that influenced most the basic and the catalytic properties of the Mg,Al-mixed oxides, with calcination under dry air being the best choice.

  8. Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    The cerium iron complex oxides oxygen carder was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carrier could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carriers were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carder: the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species (bulk lattice oxygen) that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction con-dition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

  9. Precipitation of antimony from the solution of sodium thioantimonite by air oxidation in the presence of catalytic agents

    Institute of Scientific and Technical Information of China (English)

    杨天足; 赖琼琳; 唐建军; 楚广

    2002-01-01

    The behavior of antimony oxidation in the solution of sodium thioantimonite was studied in the presence of catalytic agents. The catalytic effects of the respective addition of cupric sulfate, sodium tartrate, potassium permanganate, phenol, 1,2-dihydroxybenzene and their combination on the oxidation of sodium thioantimonite were investigated. A pilot test was carried out. The results show that the respective use of sodium tartrate, cupric sulfate, potassium permanganate, phenol and 1,2-dihydroxybenzene have little catalytic effect on the oxidation of sodium thioantimonite. However there exists obvious catalytic oxidation by the combination of 0.25 g/L 1,2-dihydroxybenzene, 0.5 g/L potassium permanganate and 1.0 g/L phenol. Moreover, high blast intensity, the increase of temperature and NaOH concentration favor the oxidation of antimony. The oxidation process of antimony has such advantages as quick reaction and low operation costs. The results of the pilot test are consistent with those of laboratory experiments.

  10. Iron-oxide-supported nanocarbon in lithium-ion batteries, medical, catalytic, and environmental applications.

    Science.gov (United States)

    Tuček, Jiří; Kemp, Kingsley Christian; Kim, Kwang Soo; Zbořil, Radek

    2014-08-26

    Owing to the three different orbital hybridizations carbon can adopt, the existence of various carbon nanoallotropes differing also in dimensionality has been already affirmed with other structures predicted and expected to emerge in the future. Despite numerous unique features and applications of 2D graphene, 1D carbon nanotubes, or 0D fullerenes, nanodiamonds, and carbon quantum dots, which have been already heavily explored, any of the existing carbon allotropes do not offer competitive magnetic properties. For challenging applications, carbon nanoallotropes are functionalized with magnetic species, especially of iron oxide nature, due to their interesting magnetic properties (superparamagnetism and strong magnetic response under external magnetic fields), easy availability, biocompatibility, and low cost. In addition, combination of iron oxides (magnetite, maghemite, hematite) and carbon nanostructures brings enhanced electrochemical performance and (photo)catalytic capability due to synergetic and cooperative effects. This work aims at reviewing these advanced applications of iron-oxide-supported nanocarbon composites where iron oxides play a diverse role. Various architectures of carbon/iron oxide nanocomposites, their synthetic procedures, physicochemical properties, and applications are discussed in details. A special attention is devoted to hybrids of carbon nanotubes and rare forms (mesoporous carbon, nanofoam) with magnetic iron oxide carriers for advanced environmental technologies. The review also covers the huge application potential of graphene/iron oxide nanocomposites in the field of energy storage, biomedicine, and remediation of environment. Among various discussed medical applications, magnetic composites of zero-dimensional fullerenes and carbon dots are emphasized as promising candidates for complex theranostics and dual magneto-fluorescence imaging. PMID:25000534

  11. Electrochemical sensing chemical oxygen demand based on the catalytic activity of cobalt oxide film

    International Nuclear Information System (INIS)

    Highlights: ► A novel electrochemical sensor was developed for COD using cobalt oxide film. ► It exhibited high sensitivity, rapid response, good simplicity and practicability. ► It was used in numerous water samples, and accuracy was tested by standard method. - Abstract: Cobalt oxide sensing film was in situ prepared on glassy carbon electrode surface via constant potential oxidation. Controlling at 0.8 V in NaOH solution, the high-valence cobalt catalytically oxidized the reduced compounds, decreasing its surface amount and current signal. The current decline was used as the response signal of chemical oxygen demand (COD) because COD represents the summation of reduced compounds in water. The surface morphology and electrocatalytic activity of cobalt oxide were readily tuned by variation of deposition potential, time, medium and Co2+ concentration. As confirmed from the atomic force microscopy measurements, the cobalt oxide film, that prepared at 1.3 V for 40 s in pH 4.6 acetate buffer containing 10 mM Co(NO3)2, possesses large surface roughness and numerous three-dimensional structures. Electrochemical tests indicated that the prepared cobalt oxide exhibited high electrocatalytic activity to the reduced compounds, accompanied with strong COD signal enhancement. As a result, a novel electrochemical sensor with high sensitivity, rapid response and operational simplicity was developed for COD. The detection limit was as low as 1.1 mg L−1. The analytical application was studied using a large number of lake water samples, and the accuracy was tested by standard method.

  12. Mechanism of catalytic action of oxide systems in reactions of aldehyde oxidation to carboxylic acids

    International Nuclear Information System (INIS)

    Mechanism of selective action of oxide catalysts (on the base of V2O4, MoO3) of aldehyde oxidation to acids is considered, reaction acrolein oxidation to acrylic acid is taken as an example. Multistage mechanism of the process is established; it involves consequent transformation of coordination-bonded aldehyde into carbonyl-bonded aldehyde and symmetric carboxylate. Principles of active surface construction are formulated, they take into account the activity of stabilization center of concrete intermediate compound and bond energy of oxygen with surface. (author)

  13. The role of oxygen during the catalytic oxidation of ammonia on Co3O4(1 0 0)

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Ammonia oxidation on Co3O4(1 0 0) surface is studied using Density Functional Theory. • The role of lattice O, on-surface O and OH in the dehydrogenation of ammonia is clarified. • NO and H2O are the main products of ammonia oxidation on Co3O4(1 0 0). • The Co3O4 surface is itself capable of oxidising NH3 to NO using the lattice O, opening the way for a Mars–van Krevelen mechanism of reaction. - Abstract: The adsorption selectivity and dehydrogenation energy barriers of NH3, NH2 and NH on the (1 0 0) surface planes of Co3O4 are determined by means of density functional methods. Stepwise hydrogen abstraction is effected by lattice O3o associated with octahedrally coordinated surface Co atoms. The final H-abstraction, from NH, leads directly to the formation of gaseous product NO with the creation of a lattice oxygen vacancy. Reaction of this vacancy with gas-phase O2 repairs the vacancy and creates surface-adsorbed O* which is also capable of abstracting H from NH3*, NH2* and NH*, the final step leading to directly again to NO formation. The mobile surface OH* formed from the O*-mediated abstraction steps is also capable of abstracting H from the NHx* species, leading ultimately to surface N* which then easily extracts a lattice O3o to form NO and a new vacancy. The overall mechanism to form NO is a complex cycle of lattice- and surface-mediated abstractions. The hydrogen budget in the reaction shows corresponding complexity. Surface H* (formed when lattice O3o abstracts H from NHx) is stable and immobile but it can be abstracted by surface OH* to form water. OH* disproportionation reaction also forms water

  14. A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II

    Science.gov (United States)

    Schulze, Marcus; Kunz, Valentin; Frischmann, Peter D.; Würthner, Frank

    2016-06-01

    Mimicking the ingenuity of nature and exploiting the billions of years over which natural selection has developed numerous effective biochemical conversions is one of the most successful strategies in a chemist's toolbox. However, an inability to replicate the elegance and efficiency of the oxygen-evolving complex of photosystem II (OEC-PSII) in its oxidation of water into O2 is a significant bottleneck in the development of a closed-loop sustainable energy cycle. Here, we present an artificial metallosupramolecular macrocycle that gathers three Ru(bda) centres (bda = 2,2‧-bipyridine-6,6‧-dicarboxylic acid) that catalyses water oxidation. The macrocyclic architecture accelerates the rate of water oxidation via a water nucleophilic attack mechanism, similar to the mechanism exhibited by OEC-PSII, and reaches remarkable catalytic turnover frequencies >100 s–1. Photo-driven water oxidation yields outstanding activity, even in the nM concentration regime, with a turnover number of >1,255 and turnover frequency of >13.1 s–1.

  15. Growth and morphology of carbon nanostructures on nickel oxide nanoparticles in catalytic chemical vapor deposition

    Science.gov (United States)

    Jana, M.; Sil, A.; Ray, S.

    2014-07-01

    The present study explores the conditions favorable for the growth of cylindrical carbon nanostructures such as multi-walled carbon nanotube (MWCNT) and carbon nanofiber by catalytic chemical vapor deposition (CCVD) method using nickel oxide-based catalyst nanoparticles of different average sizes as well as different levels of doping by copper oxide. The role of doping and the average size have been related to the observed melting behavior of nanoparticles of nickel oxide by thermal and diffraction analysis, and the importance of melting has been highlighted in the context of growth of cylindrical nanostructures. In the reducing environment prevailing in the CCVD chamber due to decomposition of flowing acetylene gas at elevated temperature, there is extensive reduction of oxide nanoparticles. Lack of melting and faster flow of carbon-bearing gases favor the formation of a carbon deposit cover over the catalyst nanoparticles giving rise to the formation of nanobeads. Melting allows rapid diffusion of carbon from the surface to inside catalyst particles, and reduced flow of gas lowers the rate of carbon deposit, both creating conditions favorable for the formation of cylindrical nanostructures, which grows around the catalyst particles. Smaller particle size and lower doping favor growth of MWCNT, while growth of fiber is commonly observed on larger particles having relatively higher level of doping.

  16. A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II.

    Science.gov (United States)

    Schulze, Marcus; Kunz, Valentin; Frischmann, Peter D; Würthner, Frank

    2016-06-01

    Mimicking the ingenuity of nature and exploiting the billions of years over which natural selection has developed numerous effective biochemical conversions is one of the most successful strategies in a chemist's toolbox. However, an inability to replicate the elegance and efficiency of the oxygen-evolving complex of photosystem II (OEC-PSII) in its oxidation of water into O2 is a significant bottleneck in the development of a closed-loop sustainable energy cycle. Here, we present an artificial metallosupramolecular macrocycle that gathers three Ru(bda) centres (bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) that catalyses water oxidation. The macrocyclic architecture accelerates the rate of water oxidation via a water nucleophilic attack mechanism, similar to the mechanism exhibited by OEC-PSII, and reaches remarkable catalytic turnover frequencies >100 s(-1). Photo-driven water oxidation yields outstanding activity, even in the nM concentration regime, with a turnover number of >1,255 and turnover frequency of >13.1 s(-1). PMID:27219702

  17. Conversion of the refractory ammonia and acetic acid in catalytic wet air oxidation of animal byproducts

    Institute of Scientific and Technical Information of China (English)

    Virginie Fontanier; Sofiane Zalouk; Stéphane Barbati

    2011-01-01

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) of slaughtered animal byproducts (ABPs) were investigated.Two step experiment was carried out consisting ofa non-catalysed WAO run followed by a CWAO run at 170-275℃, 20 MPa, and reaction time 180 min.The WAO (1st step) of sample (5 g/L total organic carbon (TOC)) yielded (82.0 ± 4)% TOC removal and (78.4 ± 13.2)%conversion of the initial organic-N into NH4+-N.Four metal catalysts (Pd, Pt, Rh, Ru) supported over alumina have been tested in catalytic WAO (2nd step) at elevated pH to enhance ammonia conversion and organic matter removal, particularly acetic acid.It was found that the catalysts Ru, Pt, and Rh had significant effects on the TOC removal (95.1%, 99.5% and 96.7%, respectively) and on the abatement of ammonia (93.4%, 96.7% and 96.3%, respectively) with high nitrogen selectivity.The catalyst Pd was found to have the less activity while Pt had the best performance.The X-Ray diffraction analysis showed that the support of catalyst was not stable under the experimental conditions since it reacted with phosphate present in solution.Nitrite and nitrate ions were monitored during the oxidation reaction and it was concluded that CWAO of ammonia in real waste treatment framework was in good agreement with the results obtained from the literature for ideal solutions of ammonia.

  18. Pincer and diamine Ru and Os diphosphane complexes as efficient catalysts for the dehydrogenation of alcohols to ketones.

    Science.gov (United States)

    Baratta, Walter; Bossi, Gianluca; Putignano, Elisabetta; Rigo, Pierluigi

    2011-03-14

    The ruthenium and osmium complexes [MCl(2)(diphosphane)(L)] (M=Ru, Os; L=bidentate amino ligand) and [MCl(CNN)(dppb)] (CNN=pincer ligand; dppb=1,4-bis-(diphenylphosphino)butane), containing the N−H moiety, have been found to catalyze the acceptorless dehydrogenation of alcohols in tBuOH and in the presence of KOtBu. The compounds trans-[MCl(2)(dppf)(en)] (M=Ru 7, Os 13; dppf=1,1'-bisdiphenylphosphino)ferrocene; en=ethylenediamine) display very high activity and different substrates, including cyclic and linear alcohols, are efficiently oxidized to ketones by using 0.8-0.04 mol % of catalyst. The effect of the base and the comparison of the catalytic activity of the Ru versus Os complexes are reported. The ruthenium complex 7 generally leads to a faster conversion into ketones with respect to the osmium complex 13, which displays better activity in the dehydrogenation of 5-en-3β-hydroxy steroids. The synthesis of new Ru and Os complexes [MCl(2)(PP)(L)] (PP=dppb, dppf; L=(±)-trans-1,2-diaminocyclohexane,2-(aminomethyl)pyridine, and 2-aminoethanol) of trans and cis configuration is also reported. PMID:21341330

  19. Role of iron oxide catalysts in selective catalytic reduction of NOx and soot from vehicular emission

    International Nuclear Information System (INIS)

    This study deals with Iron containing catalysts i.e Iron oxide Fe/sub 2/O/sub 3/) Iron potassium oxide Fe/sub 1.9/K/sub 0.1/O/sub 3/, copper iron oxide Cu/sub 0.9/K/sub 0.1/, Fe/sub 2/O/sub 3/, nickel iron oxide Ni Fe/sub 2/O/sub 4/, and Nickel potassium iron oxide Ni/sub 0.95/K/sub 0.05/ Fe/sub 2/O/sub 4/ catalyst were synthesized by using PVA technique. By X-ray Diffraction technique these catalysts were characterized to ensure the formation of crystalline structure. Energy Dispersive X-rays analysis (EDX) was used for the confirmation of presence of different metals and Scanning Electron Microscopy (SEM) for Surface Morphology. Then the catalytic investigations of the prepared catalyst were carried out for their activity measurement toward simultaneous conversion of NOx and Soot from an engine exhaust. Some Iron containing oxide catalysts were partially modified by alkali metal potassium and were used for NOx -Soot reaction in a model exhaust gas. Fe/sub 1.9 K /sub 0.1/O/sub 3/ show high catalytic performance for N/sub 2/ formation in the prepared catalyst. Further studies have shown that Fe/sub 1.9/ K/sub 0.1/ O/sub 3/ was deactivated in a substantial way after about 20 Temperature. Temperature Programmed Reaction (TPR) experiments due to agglomeration of the promoter potassium. Experiments carried out over the aged Fe/sub 1.9/K/sub 0.1/O/sub 3/ catalyst have shown that NOx-soot reaction was suppressed at higher oxygen concentration, since O/sub 2/-soot conversion was kindly favored. More over nitrite species formed at the catalyst surface might play an important role in NOx-soot conversion. (author)

  20. Thermal catalytic oxidation of octachloronaphthalene over anatase TiO2 nanomaterial and its hypothesized mechanism

    Science.gov (United States)

    Su, Guijin; Li, Qianqian; Lu, Huijie; Zhang, Lixia; Huang, Linyan; Yan, Li; Zheng, Minghui

    2015-12-01

    As an environmentally-green technology, thermal catalytic oxidation of octachloronaphthalene (CN-75) over anatase TiO2 nanomaterials was investigated at 300 °C. A wide range of oxidation intermediates, which were investigated using various techniques, could be of three types: naphthalene-ring, single-benzene-ring, and completely ring-opened products. Reactive oxygen species on anatase TiO2 surface, such as O2-• and O2-, contributed to oxidative degradation. Based on these findings, a novel oxidation degradation mechanism was proposed. The reaction at (101) surface of anatase TiO2 was used as a model. The naphthalene-ring oxidative products with chloronaphthols and hydroxyl-pentachloronaphthalene-dione, could be formed via attacking the carbon of naphthalene ring at one or more positions by nucleophilic O2-. Lateral cleavage of the naphthalene ring at different C1-C10 and C4-C9, C1-C2 and C4-C9, C1-C2 or and C3-C4 bond positions by electrophilic O2-• could occur. This will lead to the formation of tetrachlorophenol, tetrachloro-benzoic acid, tetrachloro-phthalaldehyde, and tetrachloro-acrolein-benzoic acid, partially with further transformation into tetrachlorobenzene-dihydrodiol and tetrachloro-salicylic acid. Unexpectedly, the symmetric half section of CN-75 could be completely remained with generating the intricate oxidative intermediates characteristically containing tetrachlorobenzene structure. Complete cleavage of naphthalene ring could produce the ring-opened products, such as formic and acetic acids.

  1. Removal of ammonia from aqueous solutions by catalytic oxidation with copper-based rare earth composite metal materials: catalytic performance, characterization, and cytotoxicity evaluation

    Institute of Scientific and Technical Information of China (English)

    Chang-Mao Hung

    2011-01-01

    Ammonia (NH3) has an important use in the chemical industry and is widely found in industrial wastewater.For this investigation of copper-based rare earth composite metal materials,aqueous solutions containing 400 mg/L of ammonia were oxidized in a batch-bed reactor with a catalyst prepared by the co-precipitation of copper nitrate,lanthanum nitrate and cerium nitrate.Barely any of the dissolved ammonia was removed by wet oxidation without a catalyst,but about 88% of the ammonia was reduced during wet oxidation over the catalysts at 423 K with an oxygen partial pressure of 4.0 MPa.The catalytic redox behavior was determined by cyclic voltammetry (CV).Furthermore,the catalysts were characterized using thermogravimetric analyzer (TGA) and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX),which showed that the catalytic behavior was related to the metal oxide properties of the catalyst.In addition,the copper-lanthanum-cerium composite-induced cytotoxicity in the human lung MRC-5 cell line was tested,and the percentage cell survival was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetra-zolium (MTS) analysis in vitro.No apparent cytotoxicity was observed when the human lung cells were exposed to the copper-lanthanum-cerium composite.

  2. Dehydrogenation of Methylcyclohexane: Parametric Sensitivity of the Power Law Kinetics

    OpenAIRE

    Arthur A. Garforth; David L. Cresswell; Usman, Muhammad R.

    2013-01-01

    For heterogeneous catalytic reactions, the empirical power law model is a valuable tool that explains variation in the kinetic behavior with changes in operating conditions, and therefore aids in the development of an appropriate and robust kinetic model. In the present work, experiments are performed on 1.0 wt% Pt/Al2O3 catalyst over a wide range of experimental conditions and parametric sensitivity of the power law model to the kinetics of the dehydrogenation of methylcyclohexane is studied...

  3. Investigation of the Cu-Zr-Y oxides activity in the carbon black catalytic oxidation by differential thermal analysis and temperature programmed reduction

    International Nuclear Information System (INIS)

    Different copper/zirconium-yttrium catalysts have been tested in carbon black oxidation reaction. Supported mainly on differential thermal analysis and temperature programmed reduction, two different mechanisms have been proposed to explain the catalytic results. In the absence of copper, it has been shown that Zr3+ ions and associated anionic vacancies are responsible to the catalytic enhancement observed in the mixed oxides, oxygen species being activated on these sites. Among mixed zirconia-yttria solids, ZrO2-5 mol%Y2O3 is the most active catalyst. Copper impregnation on these oxides leads to the formation of different copper species. Small particles of CuO in low interaction with the support, induce a catalytic improvement due to the highest reducibility of these species. Moreover, in order to be more efficient, CuO species should have some interactions with the support, since impregnated samples are more active than the simple mechanical mixtures

  4. Trends in reactivity of oxides:applied to catalytic oxidation of hydrogen halides

    OpenAIRE

    Toftelund, Anja; Rossmeisl, Jan; Bligaard, Thomas

    2012-01-01

    Resultaterne i denne afhandling er baseret på beregninger udført vha. tæthedsfunktionalteori.Den katalystiske aktivitet af oxider og andre sammensatte materialer er blevet undersøgt. Det konstateres, at adsorbtionsenergien af molekylerne NH2, NH, OH og SH på overfladerne af overgangsmetalnitrid, -oxid og -sulfid skalerer lineært med adsorbtionsenergien af det centrale N, O og S atom. Det er også fundet at de følger samme tendens som adsorbtion af de samme molekyler på overgangsmetaller. Den s...

  5. Improved Aeration Process - Catalytic Role Of The Iron Oxides In Arsenic Oxidation And Coprecipitation

    DEFF Research Database (Denmark)

    Kowalski, Krysztof; Søgaard, Erik Gydesen

    2013-01-01

    improved aeration process that can also help in developing better arsenic removal treatment. The results present advantages of arsenic oxidation in an aeration process in the presence of ferrihydrite surface that have been shown to adsorb arsenic simultaneously to its oxidation. The presence of...... aeration. Moreover, it was found that the adsorption rate was limited by an excess of dissolved iron, due to competition between arsenic and iron compounds for adsorption sites on iron oxyhydroxide surface. The results were obtained both in lab and pilot scale experiments, which enabled to illustrate...

  6. Oxides Catalysts of Rare Earth and Transient Metal for Catalytic Oxidation of Benzene

    Institute of Scientific and Technical Information of China (English)

    Liang Kun; Li Rong; Chen Jianjun; Ma Jiantai

    2004-01-01

    The catalysts of CeO2 and the mixture of CeO2 and CuO were prepared, and the activities of these catalysts for completely oxidizing benzene were studied.The results show that the optimal proportion of CeO2/CuO is 6: 4.The highest temperature at which benzene was completely oxidized on these catalysts at different airspeed was measured.Compared these catalysts with the noble metal used, our catalysts had superiority in the resources and the industrial cost besides good activities.

  7. Catalytic processes during preferential oxidation of CO in H 2-rich streams over catalysts based on copper-ceria

    Science.gov (United States)

    Gamarra, D.; Hornés, A.; Koppány, Zs.; Schay, Z.; Munuera, G.; Soria, J.; Martínez-Arias, A.

    Nanostructured catalysts based on combinations between oxidised copper and cerium entities prepared by two different methods (impregnation of ceria and coprecipitation of the two components within reverse microemulsions) have been examined with respect to their catalytic performance for preferential oxidation of CO in a H 2-rich stream (CO-PROX). Correlations between their catalytic and redox properties are established on the basis of parallel analyses of temperature programmed reduction results employing both H 2 and CO as reactants as well as by XPS. Although general catalytic trends can be directly correlated with the redox properties observed upon separate interactions with each of the two reductants (CO and H 2), the existence of interferences between both reductants must be considered to complete details for such activity/redox correlation. Differences in the nature of the active oxidised copper-cerium contacts present in each case determine the catalytic properties of these systems for the CO-PROX process.

  8. Synthesis, Characterization and Shape-Dependent Catalytic CO Oxidation Performance of Ruthenium Oxide Nanomaterials: Influence of Polymer Surfactant

    Directory of Open Access Journals (Sweden)

    Antony Ananth

    2015-08-01

    Full Text Available Ruthenium oxide nano-catalysts supported on mesoporous γ-Al2O3 have been prepared by co-precipitation method and tested for CO oxidation. The effect of polyethylene glycol (PEG on the properties of the catalyst was studied. Addition of the PEG surfactant acted as a stabilizer and induced a change in the morphology of ruthenium oxide from spherical nanoparticles to one-dimensional nanorods. Total CO conversion was measured as a function of morphology at 175 °C and 200 °C with 1.0 wt.% loading for PEG-stabilized and un-stabilized catalysts, respectively. Conversion routinely increased with temperature but in each case, the PEG-stabilized catalyst exhibited a notably higher catalytic activity as compared to the un-stabilized equivalent. It can be assumed that the increase in the activity is due to the changes in porosity, shape and dispersion of the catalyst engendered by the use of PEG.

  9. Fabrication of Au–Pd nanoparticles/graphene oxide and their excellent catalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    He, Yongqiang, E-mail: heyongqiang@126.com [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Zhang, Nana; Zhang, Lei [School of Science, Tianjin University, Tianjin 300072 (China); Gong, Qiaojuan [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Yi, Maocong [School of Science, Tianjin University, Tianjin 300072 (China); Wang, Wei [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Qiu, Haixia, E-mail: qhx@tju.edu.cn [School of Science, Tianjin University, Tianjin 300072 (China); Gao, Jianping [School of Science, Tianjin University, Tianjin 300072 (China)

    2014-03-01

    Graphical abstract: - Highlights: • Au and Pd nanoparticles loaded on GO were fabricated without adding any reducing agents. • The Au–Pd NPs/GO were excellent catalysts for the reduction of 4-nitrophenol. • The Au–Pd NPs/GO showed superior catalytic activity for the Suzuki reaction. • The Au–Pd NPs/GO exhibit good reusability. - Abstract: A simple method to fabricate clean Au–Pd nanoparticles on graphene oxide (Au–Pd NPs/GO) without using any reducing agent or surfactant has been developed. GO simultaneously reduced the Au and Pd precursors to form a stable suspension of the Au–Pd NPs/GO. The nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and inductively coupled plasma. The Au–Pd NPs/GO exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol and for the Suzuki–Miyaura coupling reaction of chlorobenzene and phenylboronic acid in aqueous media.

  10. Fabrication of Au–Pd nanoparticles/graphene oxide and their excellent catalytic performance

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Au and Pd nanoparticles loaded on GO were fabricated without adding any reducing agents. • The Au–Pd NPs/GO were excellent catalysts for the reduction of 4-nitrophenol. • The Au–Pd NPs/GO showed superior catalytic activity for the Suzuki reaction. • The Au–Pd NPs/GO exhibit good reusability. - Abstract: A simple method to fabricate clean Au–Pd nanoparticles on graphene oxide (Au–Pd NPs/GO) without using any reducing agent or surfactant has been developed. GO simultaneously reduced the Au and Pd precursors to form a stable suspension of the Au–Pd NPs/GO. The nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and inductively coupled plasma. The Au–Pd NPs/GO exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol and for the Suzuki–Miyaura coupling reaction of chlorobenzene and phenylboronic acid in aqueous media

  11. Fabrication of highly catalytic silver nanoclusters/graphene oxide nanocomposite as nanotag for sensitive electrochemical immunoassay.

    Science.gov (United States)

    Wang, Jiamian; Wang, Xiuyun; Wu, Shuo; Song, Jie; Zhao, Yanqiu; Ge, Yanqiu; Meng, Changgong

    2016-02-01

    Silver nanoclusters and graphene oxide nanocomposite (AgNCs/GRO) is synthesized and functionalized with detection antibody for highly sensitive electrochemical sensing of carcinoembryonic antigen (CEA), a model tumor marker involved in many cancers. AgNCs with large surface area and abundant amount of low-coordinated sites are synthesized with DNA as template and exhibit high catalytic activity towards the electrochemical reduction of H2O2. GRO is employed to assemble with AgNCs because it has large specific surface area, super electronic conductivity and strong π-π stacking interaction with the hydrophobic bases of DNA, which can further improve the catalytic ability of the AgNCs. Using AgNCs/GRO as signal amplification tag, an enzyme-free electrochemical immunosensing protocol is designed for the highly sensitive detection of CEA on the capture antibody functionalized immunosensing interface. Under optimal conditions, the designed immunosensor exhibits a wide linear range from 0.1 pg mL(-1) to 100 ng mL(-1) and a low limit of detection of 0.037 pg mL(-1). Practical sample analysis reveals the sensor has good accuracy and reproducibility, indicating the great application prospective of the AgNCs/GRO in fabricating highly sensitive immunosensors, which can be extended to the detection of various kinds of low abundance disease related proteins. PMID:26772127

  12. Modeling of adsorber/desorber/catalytic reactor system for ethylene oxide removal

    Directory of Open Access Journals (Sweden)

    ZELJKO B. GRBAVCIC

    2004-12-01

    Full Text Available The removal of ethylene oxide (EtO in a combined system adsorber/desorber/catalytic reactor has been investigated. The combined system was a modified draft tube spouted bed reactor loaded with Pt/Al2O3 catalyst. The annular region was divided into two sectons, the “hot” section contained about 7 % of catalyst and it behaved as a desorber and catalytic incinerator, while the “cold” section, with the rest of the catalyst, behaved as a sorber. The catalyst particles were circulated between the two sections by use of a draft tube riser. The Computational Fluid Dynamics (CFD program package FLUENT was used for simulations of the operation of the combined system. In addition, a one-dimensional numerical model for the operation of the packed bed reactor was compared with the corresponding FLUENT calculations. The results of the FLUENT simulations are in very good agreement with the experimental observations, as well as with the results of the one-dimensional numerical simulations.

  13. Characterization of microstructure and catalytic of cerium oxide obtained by colloidal solution

    International Nuclear Information System (INIS)

    This study investigated to obtain particles of cerium oxide, for use as catalysts for the combustion of methane using the technique of through polymeric colloidal solution. Obtaining the colloidal system is based on hydrolysis of salts such as cerium acetylacetonate, cerium nitrate in the presence of additives such as polyvinylbutyral (PVB), polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA), at concentrations of 5, 10 and 15% in aqueous or alcoholic medium. These solutions containing ions of interest were subjected to a heat treatment at 650° C for 30 minutes, with heating rate of 2 ° C/ min. After heat treatment, the fibers were characterized according to their morphology, surface area, crystallinity, weight loss and catalytic activity. Samples obtained from cerium acetylacetonate were more reactive than the cerium nitrate to the combustion of methane, as showed greater conversions and higher temperatures reached during the process, which is of utmost importance since the combustion catalytic methane is used for generating thermal energy. After the reaction with methane, the samples underwent significant change in surface area, probably due to the intensity of combustion reactions of the nitrate and the generation of heat involved in this reaction, which gave rise to coarse particles. During the combustion process using the obtained from particles of cerium acetylacetonate, there was the release of large quantities of nitrogen compared to the results of assays with the particles obtained with cerium nitrate. (author)

  14. Identification of Subnanometric Ag Species, Their Interaction with Supports and Role in Catalytic CO Oxidation

    Directory of Open Access Journals (Sweden)

    Yulia Kotolevich

    2016-04-01

    Full Text Available The nature and size of the real active species of nanoparticulated metal supported catalysts is still an unresolved question. The technique of choice to measure particle sizes at the nanoscale, HRTEM, has a practical limit of 1 nm. This work is aimed to identify the catalytic role of subnanometer species and methods to detect and characterize them. In this frame, we investigated the sensitivity to redox pretreatments of Ag/Fe/TiO2, Ag/Mg/TiO2 and Ag/Ce/TiO2 catalysts in CO oxidation. The joint application of HRTEM, SR-XRD, DRS, XPS, EXAFS and XANES methods indicated that most of the silver in all samples is in the form of Ag species with size <1 nm. The differences in catalytic properties and sensitivity to pretreatments, observed for the studied Ag catalysts, could not be explained taking into account only the Ag particles whose size distribution is measured by HRTEM, but may be explained by the presence of the subnanometer Ag species, undetectable by HRTEM, and their interaction with supports. This result highlights their role as active species and the need to take them into account to understand integrally the catalysis by supported nanometals.

  15. Synthesis and catalytic properties of microemulsion-derived cerium oxide nanoparticles

    Science.gov (United States)

    Kockrick, Emanuel; Schrage, Christian; Grigas, Anett; Geiger, Dorin; Kaskel, Stefan

    2008-07-01

    The synthesis of cerium dioxide nanoparticles using an inverse microemulsion technique and precipitation method was investigated. Cerium hydroxide nanoparticles were synthesized by adding diluted ammonia to n-heptane-surfactant-cerium nitrate system. The micelle and particle size in the range of 5-12 nm were controlled by varying the molar water to surfactant ratio and analyzed by dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM). Cerium hydroxide nanoparticles were isolated and subsequently treated at 100-600 °C to obtain nanoscale ceria. Crystallite sizes of cerium dioxide in the range of 6-16 nm were estimated by Scherrer analysis by X-ray diffraction (XRD) and HRTEM. The catalytic activity of particles annealed at 400 and 600 °C in soot combustion reactions was characterized by temperature-programmed oxidation (TPO) indicating a size-dependant activity. Crystallite sizes and catalytic stability of elevated ceria systems were tested in second combustion cycles.

  16. Membrane catalysis in the dehydrogenation and hydrogen production processes

    International Nuclear Information System (INIS)

    Data on the applications of membrane catalysis in the dehydrogenation of organic compounds and hydrogen production are analyzed and generalized. It is shown that the integration of membrane reactors into existing plants is necessary for production of hydrogen of high purity. The steam reforming and oxidative reforming of methane and steam reforming of light alcohols seem to be the most promising processes for hydrogen production in membrane reactors. The bibliography includes 165 references.

  17. Catalytic oxidation of xanthine by the nanostructured poly(aniline-co-2,4-diaminophenol)

    International Nuclear Information System (INIS)

    Poly(aniline-co-2,4-diaminophenol) (PADAP) was synthesized in a solution containing aniline, 2,4-diaminophenol (DAP) and sulfuric acid, using potentiostatic method. The image of a PADAP film is constructed of spherical particles with an average diameter of 50 nm, which was examined by both scanning electron microscope (SEM) and atomic force microscopy (AFM). The nanostructured PADAP can catalyze xanthine oxidation under a less positive potential of 0.31 V (vs. SCE), which was proved by cyclic voltammetry and amperometric method. The PADAP electrode has a very fast response for the determination of xanthine. The response current of the PADAP electrode increases with increasing xanthine concentration and applied potential. The catalytic mechanism for the oxidation of xanthine on the nanostructured PADAP electrode is similar to that of xanthine oxidase-catalyzed reaction. Experimental evidence for the electrocatalytic mechanism of xanthine oxidation on a PADAP electrode was demonstrated via measurements of the open-circuit potential and the in situ chemical-ESR spectra of PADAP in the solutions without and with xanthine, respectively.

  18. Removal of radionuclides from partitioning waste solutions by adsorption and catalytic oxidation methods

    Energy Technology Data Exchange (ETDEWEB)

    Yamagishi, Isao; Yamaguchi, Isoo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kubota, Masumitsu [Research Organization for Information Science and Technology (RIST), Tokai, Ibaraki (Japan)

    2000-09-01

    Adsorption of radionuclides with inorganic ion exchangers and catalytic oxidation of a complexant were studied for the decontamination of waste solutions generated in past partitioning tests with high-level liquid waste. Granulated ferrocyanide and titanic acid were used for adsorption of Cs and Sr, respectively, from an alkaline solution resulting from direct neutralization of an acidic waste solution. Both Na and Ba inhibited adsorption of Sr but Na did not that of Cs. These exchangers adsorbed Cs and Sr at low concentration with distribution coefficients of more than 10{sup 4}ml/g from 2M Na solution of pH11. Overall decontamination factors (DFs) of Cs and total {beta} nuclides exceeded 10{sup 5} and 10{sup 3}, respectively, at the neutralization-adsorption step of actual waste solutions free from a complexant. The DF of total {alpha} nuclides was less than 10{sup 3} for a waste solution containing diethylenetriaminepentaacetic acid (DTPA). DTPA was rapidly oxidized by nitric acid in the presence of a platinum catalyst, and radionuclides were removed as precipitates by neutralization of the resultant solution. The DF of {alpha} nuclides increased to 8x10{sup 4} by addition of the oxidation step. The DFs of Sb and Co were quite low through the adsorption step. A synthesized Ti-base exchanger (PTC) could remove Sb with the DF of more than 4x10{sup 3}. (author)

  19. Single-Site Palladium(II) Catalyst for Oxidative Heck Reaction: Catalytic Performance and Kinetic Investigations

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hui; Li, Mengyang; Zhang, Guanghui; Gallagher, James R.; Huang, Zhiliang; Sun, Yu; Luo, Zhong; Chen, Hongzhong; Miller, Jeffrey T.; Zou, Ruqiang; Lei, Aiwen; Zhao, Yanli

    2015-01-01

    ABSTRACT: The development of organometallic single-site catalysts (SSCs) has inspired the designs of new heterogeneous catalysts with high efficiency. Nevertheless, the application of SSCs in certain modern organic reactions, such as C-C bond formation reactions, has still been less investigated. In this study, a single-site Pd(II) catalyst was developed, where 2,2'-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd(II) complex. The overall performance of the single-site Pd(II) catalyst in the oxidative Heck reaction was then investigated. The investigation results show that the catalyst displays over 99% selectivity for the product formation with high reaction yield. Kinetic profiles further confirm its high catalytic efficiency, showing that the rate constant is nearly 40 times higher than that for the free Pd(II) salt. X-ray absorption spectroscopy reveals that the catalyst has remarkable lifetime and recyclability.

  20. Graphene oxide supported Au–Ag alloy nanoparticles with different shapes and their high catalytic activities

    International Nuclear Information System (INIS)

    A simple method was developed to fabricate Au–Ag nanoparticle/graphene oxide nanocomposites (Au–Ag/GO) by using simultaneous redox reactions between AgNO3, HAuCl4 and GO. The Au–Ag/GO was characterized by x-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive x-ray spectroscopy. The GO nanosheets acted as the reducing agent and the support for the Au–Ag alloy nanoparticles. In addition, Au–Ag alloy nanoparticles with different shapes including core–shell-like, dendrimer-like and flower-like were obtained by simply modifying the concentration of the reactants and the reaction temperature. With no reducing or stabilizing agents added, the Au–Ag/GO nanocomposites show superior catalytic performance for the reduction of 4-nitrophenol and for the aerobic homocoupling of phenylboronic acid. (paper)

  1. Catalytic wet peroxide oxidation of phenol solutions over CuO/CeO2 systems

    International Nuclear Information System (INIS)

    Three 5% CuO/CeO2 catalysts were synthesized by sol-gel, precipitation and combustion methods, followed by incipient wetness impregnation with copper nitrate. The samples were characterized by XRD, TPR, BET and tested for the catalytic wet peroxide oxidation of a phenol solution (5 g/L). The reaction took place in a batch reactor at atmospheric pressure, in a temperature range of 60-80°C , during 4 h. Phenol conversion, H2O2 consumption, pH and chemical oxygen demand were determined. The reaction temperature and the catalyst loading did improve the phenol and the H2O2 conversions. The effect on the selectivity towards complete mineralization was less marked, with levels among 60-70%. Stepwise addition of H2O2 was also tested.

  2. Study on Catalytic Wet Oxidation of H2S into Sulfur on Fe/Cu Catalyst

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A wet catalytic oxidation at room temperature was investigated with solution containing ferric, ferrous and cupric ions for H2S removal. The experiments were carried out in a two step process,and the results obtained show that the removal efficiency of H2S can always reach 100% in a 300 mm scrubbing column with four sieve plates, and the regeneration of ferric ions in 200 mm bubble column can match the consumed ferric species in absorption. Removal of H2S, production of elemental sulfur and regeneration of ferric, cupric ions can all be accomplished at the same time. No raw material is consumed except O2 in flue gas or air, the process has no secondary pollution and no problem of catalyst degradation and congestion.

  3. Dynamic\tmodelling of catalytic three-phase reactors for hydrogenation and oxidation processes

    Directory of Open Access Journals (Sweden)

    Salmi T.

    2000-01-01

    Full Text Available The dynamic modelling principles for typical catalytic three-phase reactors, batch autoclaves and fixed (trickle beds were described. The models consist of balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. Rate equations, transport models and mass balances were coupled to generalized heterogeneous models which were solved with respect to time and space with algorithms suitable for stiff differential equations. The aspects of numerical solution strategies were discussed and the procedure was illustrated with three case studies: hydrogenation of aromatics, hydrogenation of aldehydes and oxidation of ferrosulphate. The case studies revealed the importance of mass transfer resistance inside the catalyst pallets as well as the dynamics of the different phases being present in the reactor. Reliable three-phase reactor simulation and scale-up should be based on dynamic heterogeneous models.

  4. Catalytic and electrocatalytic oxidation of carbon monoxide on a Fe electrode in a solid electrolyte cell

    International Nuclear Information System (INIS)

    The catalytic oxidation of carbon monoxide on Fe catalyst was studied at 300-500C and atmospheric total pressure. The reaction was studied under both open- and closed-circuit operation in an yttria-stabilized zirconia solid electrolyte cell. The technique of Solid Electrolyte Potentiometry (SEP) was used to monitor the thermodynamic activity of oxygen adsorbed on the Fe electrode under open circuit. Kinetic and potentiometric measurements were combined in order to elucidate the reaction mechanism. The results are in agreement with a Langmuir-Hinselwood type of adsorption-reaction with two different adsorption sites for carbon monoxide and oxygen. Under closed circuit, the effect of electrochemical oxygen 'pumping' to the catalyst was examined. The operation of the cell was almost Faradaic as the rate enhancement factor (λ) values measured were close to unity

  5. Identification of Subnanometric Ag Species, Their Interaction with Supports and Role in Catalytic CO Oxidation.

    Science.gov (United States)

    Kotolevich, Yulia; Kolobova, Ekaterina; Khramov, Evgeniy; Cabrera Ortega, Jesús Efren; Farías, Mario H; Zubavichus, Yan; Zanella, Rodolfo; Mota-Morales, Josué D; Pestryakov, Alexey; Bogdanchikova, Nina; Cortés Corberán, Vicente

    2016-01-01

    The nature and size of the real active species of nanoparticulated metal supported catalysts is still an unresolved question. The technique of choice to measure particle sizes at the nanoscale, HRTEM, has a practical limit of 1 nm. This work is aimed to identify the catalytic role of subnanometer species and methods to detect and characterize them. In this frame, we investigated the sensitivity to redox pretreatments of Ag/Fe/TiO₂, Ag/Mg/TiO₂ and Ag/Ce/TiO₂ catalysts in CO oxidation. The joint application of HRTEM, SR-XRD, DRS, XPS, EXAFS and XANES methods indicated that most of the silver in all samples is in the form of Ag species with size nanometals. PMID:27110757

  6. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    Directory of Open Access Journals (Sweden)

    Kabljanac, Ž.

    2011-11-01

    Full Text Available This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comparison with designed capacity for one production line is shown in the Table 1. Shown is the effectiveness of selective catalytic reduction in the temperature range of the tail gas from 180 to 230 °C with direct application of liquid ammonia, without prior evaporation to gaseous state. The results of inlet and outlet concentrations of nitrous oxides in the tail gas of the nitric acid production process are shown in Figures 1 and 2. Figure 3 shows the temperature dependence of the selective catalytic reduction of nitrous oxides expressed as NO2in the tail gas of nitric acid production with the application of a constant mass flow of liquid ammonia of 13,0 kg h-1 and average inlet mass concentration of the nitrous oxides expressed as NO2of 800,0 mgm-3 during 100 % production capacity. The specially designed liquid-ammonia direct-dosing system along with the effective homogenization of the tail gas resulted in emission levels of nitrous oxides expressed as NO2 in tail gas ranging from 100,0 to 185,0 mg m-3. The applied low-temperature selective catalytic reduction of the nitrous oxides in the tail gases by direct use of liquid ammonia is shown in Figure 4. It is shown that low-temperature selective catalytic reduction with direct application of liquid ammonia opens a new opportunity in the reduction of nitrous oxide emissions during nitric acid production without the risk of dangerous ammonium nitrate occurring in the process of subsequent energy utilization of

  7. Catalytic combustion of soot over Ru-doped mixed oxides catalysts

    Institute of Scientific and Technical Information of China (English)

    LF Nascimento; RF Martins; OA Serra

    2014-01-01

    We employed modified substrates as outer heterogeneous catalysts to reduce the soot originating from the incomplete die-sel combustion. Here, we proposed that ceria (CeO2)-based catalysts could lower the temperature at which soot combustion occurred from 610 ºC to values included in the operation range of diesel exhausts (270-400 ºC). Here, we used the sol-gel method to synthesize catalysts based on mixed oxides (ZnO:CeO2) deposited on cordierite substrates, and modified by ruthenium nanoparticles. The presence of ZnO in these mixed oxides produced defects associated with oxygen vacancies, improving thermal stability, redox potential, sulfur resistance, and oxygen storage. We evaluated the morphological and structural properties of the material by X-ray diffraction (XRD), Brumauer-emmett-teller method (BET), temperature programmed reduction (H2-TPR), scanning electron micros-copy (SEM), and transmission electron microscopy (TEM). We investigated how the addition of Ru (0.5 wt.%) affected the catalytic activity of ZnO:CeO2 in terms of soot combustion. Thermogravimetric analysis (TG/DTA) revealed that presence of the catalyst de-creased the soot combustion temperature by 250 ºC, indicating that the oxygen species arose at low temperatures, which was the main reason for the high reactivity of the oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy (DRS) showed that the catalyst containing Ru on the mixed oxide-impregnated cordierite samples efficiently oxidized soot in a diesel stationary motor:soot emission decreased 80%.

  8. Oxidative destruction of biomolecules by gasoline engine exhaust products and detoxifying effects of the three-way catalytic converter.

    Science.gov (United States)

    Blaurock, B; Hippeli, S; Metz, N; Elstner, E F

    1992-01-01

    Aqueous solutions of engine exhaust condensation products were derived from cars powered by diesel or four-stroke gasoline engines (with and without three-way catalytic converter). The cars were operated on a static test platform. Samples of the different exhaust solutions accumulated in a Grimmer-type distillation trap (VDI 3872) during standard test programs (Federal Test Procedure) were incubated with important biomolecules. As indicators of reactive oxygen species or oxidative destruction, ascorbic acid, cysteine, glutathione, serum albumin, the enzymes glycerinaldehyde phosphate dehydrogenase and xanthine oxidase, and the oxygen free-radical indicator keto-methylthiobutyrate were used. During and after the incubations, oxygen activation (consumption) and oxidative destruction were determined. Comparison of the oxidative activities of the different types of exhaust condensates clearly showed that the exhaust condensate derived from the four-stroke car equipped with a three-way catalytic converter exhibited by far the lowest oxidative and destructive power. PMID:1283938

  9. Catalysts for Dehydrogenation of ammonia boranes

    Energy Technology Data Exchange (ETDEWEB)

    Heinekey, Dennis M.

    2014-12-19

    Several effective homogeneous catalysts for the dehydrogenation of amine boranes have been developed. The best catalyst uses an iridium complex, and is capable of dehydrogenating H3NBH3 (AB) and CH3NH2BH3 (MeAB) at comparable rates. Thermodynamic measurements using this catalyst demonstrate that the dehydrogenation of AB and MeAB is substantially exothermic, which has important implications for regeneration.

  10. A DFT study on the Cu (1 1 1) surface for ethyl acetate synthesis from ethanol dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Li Ruzhen; Zhang Minhua [Key Laboratory for Green Chemical Technology of Ministry of Education, Tianjin University R and D Center for Petrochemical Technology, Tianjin (China); Yu Yingzhe, E-mail: lrz1699@126.com [Key Laboratory for Green Chemical Technology of Ministry of Education, Tianjin University R and D Center for Petrochemical Technology, Tianjin (China)

    2012-07-01

    Copper-based catalysts have shown excellent catalytic performances. Despite extensive studies in the field, the microscopic mechanism of ethanol dehydrogenation to ethyl acetate (EA) on Cu-based catalysts remains controversial. Aiming to provide insight into the catalytic roles of Cu, density functional theory (DFT) calculations have been performed to study the elementary reactions involved in ethanol dehydrogenation to EA on Cu surfaces. In this work, the adsorption properties of ethanol, ethoxy, acetaldehyde, acetyl and EA on the Cu (1 1 1) catalyst surface were investigated. Based on two pathways, many transition states involved are located. The results show that the route proposed by Colley is more likely to happen.

  11. ONO-pincer ruthenium complex-bound norvaline for efficient catalytic oxidation of methoxybenzenes with hydrogen peroxide.

    Science.gov (United States)

    Yoshida, Ryota; Isozaki, Katsuhiro; Yokoi, Tomoya; Yasuda, Nobuhiro; Sadakane, Koichiro; Iwamoto, Takahiro; Takaya, Hikaru; Nakamura, Masaharu

    2016-08-21

    The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-l-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity. PMID:27314504

  12. MERCURY OXIDATION PROMOTED BY A SELECTIVE CATALYTIC REDUCTION CATALYST UNDER SIMULATED POWDER RIVER BASIN COAL COMBUSTION CONDITIONS

    Science.gov (United States)

    A bench-scale reactor consisting of a natural gas burner and an electrically heated reactor housing a selective catalytic reduction (SCR) catalyst was constructed for studying elemental mercury oxidation under SCR conditions. A low sulfur Power River Basin (PRB) coal combustion ...

  13. Catalytic Performance of Zeolite-Supported Vanadia in the Aerobic Oxidation of 5-hydroxymethylfurfural to 2,5- diformylfuran

    DEFF Research Database (Denmark)

    Sádaba, Irantzu; Gorbanev, Yury; Kegnæs, Søren;

    2013-01-01

    The catalytic performance of zeolite-supported vanadia catalysts was examined for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) in organic solvents such as N,N-dimethylformamide (DMF), methyl isobutyl ketone, toluene, trifluorotoluene and DMSO. Catalysts based on...

  14. Construction and biofunctional evaluation of electrospun vascular graft loaded with selenocystamine for in situ catalytic generation of nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Siyuan; An, Jun; Weng, Lei [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Li, Yandong [Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China); Xu, Han; Wang, Yaping; Ding, Dan; Kong, Deling [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Wang, Shufang, E-mail: wangshufang@nankai.edu.cn [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2014-12-01

    Construction and biofunctional evaluation of a novel vascular graft with in situ catalytic generation of nitric oxide were described in this paper. Poly α-lysine and poly (γ-glutamic acid) were deposited alternately onto the surface of an electrospun poly ε-caprolactone matrix via electrostatic layer-by-layer self-assembly, and then selenocystamine was loaded as a catalyst. Measurement of in vitro catalytic generation of nitric oxide demonstrated that this catalyst-loaded material could considerably accelerate the release of nitric oxide from S-nitrosoglutathione. A fibroblast proliferation assay showed that the material possessed satisfactory cellular compatibility. The catalyst-loaded material could inhibit the spread of smooth muscle cells in the presence of nitric oxide donors. In arteriovenous-shunt experiment, the catalyst-loaded graft exhibited good anti-thrombotic property where it could prevent acute thrombosis by decreasing the adhesion and activation of platelets and other blood cells. These data suggest a new method of building vascular grafts with improved hemocompatibility and biological functions. - Highlights: • A porous small-diameter vascular graft was prepared by electrospinning. • Selenocystamine was loaded for in situ catalytic and sustained NO generation. • There was a significant catalytic NO generation on the catalyst-loaded sample. • The spread of smooth muscle cells was inhibited on the catalyst-loaded sample. • The catalyst-loaded sample showed anti-thrombotic property in AV-shunt experiment.

  15. Catalytic upgrading of sugar fractions from pyrolysis oils in supercritical mono-alcohols over Cu doped porous metal oxide

    NARCIS (Netherlands)

    Yin, Wang; Venderbosch, Hendrikus; Bottari, Giovanni; Krawzcyk, Krzysztof K.; Barta, Katalin; Heeres, Hero Jan

    2015-01-01

    In this work, we report on the catalytic valorization of sugar fractions, obtained by aqueous phase extraction of fast pyrolysis oils, in supercritical methanol (scMeOH) and ethanol (scEtOH) over a copper doped porous metal oxide (Cu-PMO). The product mixtures obtained are, in principle, suitable fo

  16. Construction and biofunctional evaluation of electrospun vascular graft loaded with selenocystamine for in situ catalytic generation of nitric oxide

    International Nuclear Information System (INIS)

    Construction and biofunctional evaluation of a novel vascular graft with in situ catalytic generation of nitric oxide were described in this paper. Poly α-lysine and poly (γ-glutamic acid) were deposited alternately onto the surface of an electrospun poly ε-caprolactone matrix via electrostatic layer-by-layer self-assembly, and then selenocystamine was loaded as a catalyst. Measurement of in vitro catalytic generation of nitric oxide demonstrated that this catalyst-loaded material could considerably accelerate the release of nitric oxide from S-nitrosoglutathione. A fibroblast proliferation assay showed that the material possessed satisfactory cellular compatibility. The catalyst-loaded material could inhibit the spread of smooth muscle cells in the presence of nitric oxide donors. In arteriovenous-shunt experiment, the catalyst-loaded graft exhibited good anti-thrombotic property where it could prevent acute thrombosis by decreasing the adhesion and activation of platelets and other blood cells. These data suggest a new method of building vascular grafts with improved hemocompatibility and biological functions. - Highlights: • A porous small-diameter vascular graft was prepared by electrospinning. • Selenocystamine was loaded for in situ catalytic and sustained NO generation. • There was a significant catalytic NO generation on the catalyst-loaded sample. • The spread of smooth muscle cells was inhibited on the catalyst-loaded sample. • The catalyst-loaded sample showed anti-thrombotic property in AV-shunt experiment

  17. Oxidation of Borneol to Camphor Using Oxone and Catalytic Sodium Chloride: A Green Experiment for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Lang, Patrick T.; Harned, Andrew M.; Wissinger, Jane E.

    2011-01-01

    A new green oxidation procedure was developed for the undergraduate organic teaching laboratories using Oxone and a catalytic quantity of sodium chloride for the conversion of borneol to camphor. This simple 1 h, room temperature reaction afforded high quality and yield of product, was environmentally friendly, and produced negligible quantities…

  18. Preparation of macroparticle Pt-ST/DVB and Pt-PTFE and study of catalytic oxidation HT

    International Nuclear Information System (INIS)

    Macroparticle hydrophobic supporter, ST/DVB and PTFE, are prepared by two order polymerization and with a reagent for making hole through dissolving out, respectively. Then two macroparticle hydrophobic catalysts are prepared by immersing the relevant supporter in H2PtCl6 solution. The kinetics of catalytic oxidation of the catalysts to HT is studied at ambient temperature

  19. A green surfactant-assisted synthesis of hierarchical TS-1 zeolites with excellent catalytic properties for oxidative desulfurization.

    Science.gov (United States)

    Du, Shuting; Li, Fen; Sun, Qiming; Wang, Ning; Jia, Mingjun; Yu, Jihong

    2016-02-25

    Hierarchical TS-1 zeolites with uniform intracrystalline mesopores have been successfully synthesized through the hydrothermal method by using the green and cheap surfactant Triton X-100 as the mesoporous template. The resultant materials exhibit remarkably enhanced catalytic activity in oxidative desulfurization reactions compared to the conventional TS-1 zeolite. PMID:26881277

  20. Effect of Preparation Method on Catalytic Properties of Co-Mn-Al Mixed Oxide for N2O Decomposition

    Czech Academy of Sciences Publication Activity Database

    Klyushina, A.; Obalová, L.; Karásková, K.; Jirátová, Květa

    Novosibirsk: Boreskov Institute of Catalysis SB RAS, 2015 - (Bukhtiyarov, V.; Stakheev, A.), s. 1904-1905 ISBN 978-5-906376-10-7. [European Congress on Catalysis – EuropaCat-XII /12./. Kazaň (RU), 30.08.2015-04.09.2015] R&D Projects: GA ČR GA14-13750S Institutional support : RVO:67985858 Keywords : nitrous oxide * catalytic decomposition * cobalt oxides Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://hdl.handle.net/11104/0250627

  1. In situ spectroscopy of catalytically active surfaces: FTIR and EXAFS studies of CO oxidation on Pd and Au nanoparticles

    International Nuclear Information System (INIS)

    This thesis was aiming at a comprehensive investigation of the reaction mechanism of CO oxidation, applying in situ Fourier Transform Infrared (FTIR) Spectroscopy and X- Ray Absorption Spectroscopy (XAS) under reaction conditions to different industrial-grade noble metal catalysts. For alumina supported palladium nanoparticles (∼2 and 5 nm) variable oxidative pre-treatments were utilized to identify and characterize palladium (sub)oxide species in different oxidation states. In situ EXAFS and in situ FTIR spectroscopy clearly demonstrated that such substoichiometric palladiumoxides PdOx (x<1) were also present during the CO oxidation reaction. Although they may contribute to activity, the highest catalytic activity was assigned to metallic palladium. The relatively high activity of the substoichiometric palladiumoxides (as compared to fully oxidized palladium(II)oxide) was attributed to their reducibility under technically relevant conditions by CO. The study of CO oxidation on Pd/Al2O3 indicated a coexistence of metallic Pd and PdOx under reaction conditions, with metallic palladium being essential for the activation of CO and molecular O2. Under specific reaction conditions this resulted in oscillatory behavior. The mechanism of CO oxidation on titania supported gold nanoparticles (∼4 nm) was also investigated. In situ FTIR spectroscopy identified metallic gold as CO adsorption site, whereas the oxygen adsorption site was located on the titania support. Adsorption experiments with isotopically labelled 13C18O demonstrated the involvement of hydroxyl groups of the titania support in the catalytic reaction. This explained the increase in catalytic activity upon addition of small amounts of water: water dissociates on titania producing an increased number of terminal OH groups on the catalyst surface. The results suggest a 'phase boundary-mechanism' of CO oxidation on Au/TiO2, with the reaction taking place at the oxide/metal interface. (author)

  2. Cu–Ce–O mixed oxides from Ce-containing layered double hydroxide precursors: Controllable preparation and catalytic performance

    International Nuclear Information System (INIS)

    Cu/Zn/Al layered double hydroxide (LDH) precursors have been synthesized using an anion exchange method with anionic Ce complexes containing the dipicolinate (pyridine-2,6-dicarboxylate) ligand. Cu–Ce–O mixed oxides were obtained by calcination of the Ce-containing LDHs. The materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry–differential thermal analysis, elemental analysis, and low temperature N2 adsorption/desorption measurements. The results reveal that the inclusion of Ce has a significant effect on the specific surface area, pore structure, and chemical state of Cu in the resulting Cu–Ce–O mixed metal oxides. The resulting changes in composition and structure, particularly the interactions between Cu and Ce centers, significantly enhance the activity of the Ce-containing materials as catalysts for the oxidation of phenol by hydrogen peroxide. - Graphical Abstract: Cu–Ce–O mixed oxides calcined from [Ce(dipic)3]3−- intercalated Cu/Zn/Al layered double hydroxides were synthesized and displayed good catalytic performances in phenol oxidation due to the Cu–Ce interactions. Highlights: ► [Ce(dipic)3]3−-intercalated Cu/Zn/Al layered double hydroxides were synthesized. ► Cu–Ce–O mixed oxides derivated from the LDHs were characterized as catalysts. ► Presence of Ce influenced physicochemical property and catalytic performance. ► Cu–Ce interaction was largely responsible for enhanced catalytic ability.

  3. Catalytic oxidation of 2-aminophenols and ortho hydroxylation of aromatic amines by tyrosinase

    International Nuclear Information System (INIS)

    The usual substrates of tyrosinase, a copper-containing monooxygenase (EC 1.14.18.1), are monophenols and o-diphenols which are both converted to o-quinones. In this paper, the authors studied the reaction of this enzyme with two new classes of substrates: aromatic amines and o-aminophenols, structural analogues of monophenols and o-diphenols, respectively. They undergo the same catalytic reactions (ortho hydroxylation and oxidation), as documented by product analysis and kinetic studies. In the presence of tyrosinase, arylamines and o-aminophenols are converted to o-quinone imines, which are isolated as quinone anils or phenoxazones. As an example, in the presence of tyrosinase, 2-amino-3-hydroxybenzoic acid (an o-aminophenol) is converted to cinnabarinic acid, a well-known phenoxazone, while p-aminotoluene (an aromatic amine) gives rise to the formation of 5-amino-2-methyl-1,4-benzoquinone 1-(4-methylanil). Kinetic studies using an oxygen electrode show that arylamines and the corresponding monophenols exhibit similar Michaelis constants. In contrast, the reaction rates observed for aromatic amines are relatively slow as compared to monophenols. The enzymatic conversion of arylamines by tryosinase is different from the typical ones: N-oxidation and ring hydroxylation without further oxidation. This difference originates from the regiospecific hydroxylation (ortho position) and subsequent oxidation of the intermediate o-aminophenol to the corresponding o-quinone imine. Finally, the well-know monooxygenase activity of tyrosinase was also confirmed for the aromatic amine p-aminotoluene, with 18O2

  4. Rare earth oxide aero- and xerogels. Tuning porosity and catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Bjoern

    2013-11-15

    Heterogeneous catalysts to this day are still largely developed on the basis of trial and error. This is due to the great difficulty of creating custom-designed structures at the nanometer scale using traditional preparation methods. In the course of recent rapid developments in the material sciences, however, it has become possible to create materials with custom-designed properties from the macroscopic down into the nanometer range. The purpose of the present study was to make use of this potential for catalysis. The task was to modify the porosity and composition of selected rare earth oxides that promise well as catalysts with the goal of obtaining good results in terms of oxidative reactions and oxidative coupling. One major focus was on chemical sol-gel methods and in particular on what is referred to as the epoxide addition method. Extensive work was put into the characterisation and catalytic testing of aerogels and xerogels of pure rare earth oxides as well as of hybrid systems of rare earth oxides and aluminium oxide. Furthermore, thin xerogel films and macroporous monoliths were produced, the latter using a direct foaming method. The results of this work confirm the high potential of sol-gel chemistry for making porous materials of variable and controllable porosity and composition available for heterogeneous catalysis and creating more powerful catalysts. [German] Bis heute werden heterogene Katalysatoren ueberwiegend per ''trial and error'' entwickelt. Dies liegt daran, dass es mit Hilfe der traditionellen Herstellungsmethoden sehr schwierig ist, auf der Nanometerskala Strukturen gezielt herzustellen. Im Zuge der rasanten Entwicklungen in den Materialwissenschaften ist es jedoch moeglich geworden, verschiedenste Materialen mit massgeschneiderten Eigenschaften vom makroskopischen bis hinein in den Nanometerbereich herzustellen. Ziel dieser Arbeit war es, dieses Potential fuer die Katalyse zu nutzen. Dabei bestand die Aufgabe darin

  5. Hydrogenation/Dehydrogenation Performances of the MgH2-WS2 Composites

    Institute of Scientific and Technical Information of China (English)

    WANG Jiasheng; ZHANG Wei; CHENG Ying; KE Dandan; HAN Shumin

    2015-01-01

    The hydrogenation/dehydrogenation kinetics and thermodynamic behaviors of the MgH2-WS2 composites were investigated. The TPD (Temperature-Programmed-Desorption) curves showed that the onset dehydrogenation temperature of the MgH2 + 20wt% WS2 composite was 615 K, 58 K lower than that of the pristine MgH2. The kinetic measurements showed that within 21 min, the MgH2 + 20wt% WS2 composite could absorb 2.818wt% at 423 K, and release 4.244 wt% of hydrogen at 623 K, while the hydriding/dehydriding capacity of MgH2 reached only 0.979wt% and 2.319wt% respectively under identical conditions. The improvement of hydrogenation/dehydrogenation performances for the composite was attributed to the co-catalytic effect between the new phases W and MgS which formed during the ball-milling process.

  6. Superior Fe-ZSM-5 catalyst for selective catalytic reduction of nitric oxide by ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Long, R.Q.; Yang, R.T. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering

    1999-06-16

    Nitrogen oxides in the exhaust gases from combustion of fossil fuels remain a major source for air pollution and acid rain. The current technology for reducing NO{sub x} (NO + NO{sub 2}) emissions from power plants is selective catalytic reduction (SCR) with ammonia in the presence of oxygen. For the SCR reaction, V{sub 2}O{sub 5} + WO{sub 3} (or MoO{sub 3}) supported on TiO{sub 2} are the commercial catalysts. The mechanism of the reaction on the vanadia catalysts has been studied extensively, and several different mechanisms have been proposed. Ion-exchanged zeolite catalysts have also been studied, e.g., Fe-Y, Cu-ZSM-5, and Fe-ZSM-5, but the reported activities were lower than that of the commercial vanadia catalysts. The SCR technology based on vanadia catalysts is being used in Europe and Japan and is being quickly adopted in the US. However, problems associated with vanadia catalysts remain, e.g., high activity for oxidation of SO{sub 2} to SO{sub 3}, toxicity of vanadia, and formation of N{sub 2}O at high temperature. Hence, there are continuing efforts in developing new catalysts. In this paper, the authors report a superior Fe-ZSM-5 catalyst that is much more active than the commercial vanadia catalysts and does not have the deficiencies that are associated with the vanadia catalysts.

  7. Preparation, characterization and catalytic activity of uranium-antimony oxide for selective oxidation of propene

    International Nuclear Information System (INIS)

    The selective oxidation of propene to acrolein over USb3O10 was studied in a continuous flow reactor. The experimental results show that the preparation of a well-defined catalyst of uniform composition depends on the temperature and time of calcination. The kinetic data indicate that acrolein is formed via a redox mechanism in which the surface of the catalyst is partially reduced. Moessbauer spectroscopy reveals the presence of Sb5+ and Sb3+ in the used catalyst. I.r. spectroscopy shows a structural modification. On the basis of these results it is concluded that each steady-state condition is characterized by a vacancy concentration leading to the observed modifications of the catalyst. (author)

  8. Molybdatophosphoric acid as an efficient catalyst for the catalytic and chemoselective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as a commercially available oxidant

    Directory of Open Access Journals (Sweden)

    ALIREZA HASANINEJAD

    2010-03-01

    Full Text Available An efficient procedure for the chemoselective oxidation of alkyl (aryl sulfides to the corresponding sulfoxides using urea hydrogen peroxide (UHP in the presence of a catalytic amount of molybdatophosphoric acid at room temperature is described. The advantages of described method are: generality, high yield and chemoselectivity, short reaction time, low cost and compliment with green chemistry protocols.

  9. Anchoring noble metal nanoparticles on CeO2 modified reduced graphene oxide nanosheets and their enhanced catalytic properties.

    Science.gov (United States)

    Ji, Zhenyuan; Shen, Xiaoping; Xu, Yuling; Zhu, Guoxing; Chen, Kangmin

    2014-10-15

    The strategy of structurally integrating noble metal, metal oxide, and graphene is expected to offer prodigious opportunities toward emerging functions of graphene-based nanocomposites. In this study, we develop a facile two-step approach to disperse noble metal (Pt and Au) nanoparticles on the surface of CeO2 functionalized reduced graphene oxide (RGO) nanosheets. It is shown that Pt and Au with particle sizes of about 5 and 2nm are well dispersed on the surface of RGO/CeO2. The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 was used as a model reaction to quantitatively evaluate the catalytic properties of the as-synthesized RGO/Pt/CeO2 and RGO/Au/CeO2 ternary nanocomposites. In such triple-component catalysts, CeO2 nanocrystals provide unique and critical roles for optimizing the catalytic performance of noble metallic Pt and Au, allowing them to express enhanced catalytic activities in comparison with RGO/Pt and RGO/Au catalysts. In addition, a possible mechanism for the enhanced catalytic activities of the RGO/Pt/CeO2 and RGO/Au/CeO2 ternary catalysts in the reduction of 4-NP is proposed. It is expected that our prepared graphene-based triple-component composites, which inherit peculiar properties of graphene, metal oxide, and noble metal, are attractive candidates for catalysis and other applications. PMID:25080384

  10. Preparation of porous paper composites with ruthenium hydroxide and catalytic alcohol oxidation in a multiphase gas–liquid–solid reaction

    Energy Technology Data Exchange (ETDEWEB)

    Homma, Taichi [Department of Agro-Environmental Sciences, Graduate School of Bioresource and Bioenvironmental Sciences, and Biotron Application Center, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Processing Development Research Laboratory, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi 321-3497 (Japan); Kitaoka, Takuya, E-mail: tkitaoka@agr.kyushu-u.ac.jp [Department of Agro-Environmental Sciences, Graduate School of Bioresource and Bioenvironmental Sciences, and Biotron Application Center, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)

    2014-05-01

    Highlights: • Flexible and porous paper-structured Ru(OH){sub x} catalysts were prepared successfully. • Ru(OH){sub x} catalysts were dispersed on the ceramic fiber networks of paper composites. • Catalytic oxidation of benzyl alcohol proceeded efficiently in three-phase reactions. • Paper catalysts exhibited much higher performance than conventional solid catalysts. - Abstract: In situ synthesis of ruthenium hydroxide catalysts on a microporous fiber-network structure of ceramic paper composites was achieved. The efficient catalytic oxidation of alcohol was investigated in a heterogeneous, multiphase gas–liquid–solid reaction. A simple papermaking technique and subsequent immersion in a ruthenium chloride solution allowed us to fabricate novel-concept microstructured catalysts. The paper-structured catalysts possess micropores ca. 30 μm in diameter with high porosity of ca. 90%. They exhibited much higher catalytic efficiency in the O{sub 2}-mediated oxidation in toluene of benzyl alcohol to benzaldehyde in a fixed bed external loop reactor, as compared with conventional pellet- and bead-type solid catalysts. This excellent catalytic effect is possibly attributed to the porous paper composite microstructure like microreactors.

  11. Preparation of porous paper composites with ruthenium hydroxide and catalytic alcohol oxidation in a multiphase gas–liquid–solid reaction

    International Nuclear Information System (INIS)

    Highlights: • Flexible and porous paper-structured Ru(OH)x catalysts were prepared successfully. • Ru(OH)x catalysts were dispersed on the ceramic fiber networks of paper composites. • Catalytic oxidation of benzyl alcohol proceeded efficiently in three-phase reactions. • Paper catalysts exhibited much higher performance than conventional solid catalysts. - Abstract: In situ synthesis of ruthenium hydroxide catalysts on a microporous fiber-network structure of ceramic paper composites was achieved. The efficient catalytic oxidation of alcohol was investigated in a heterogeneous, multiphase gas–liquid–solid reaction. A simple papermaking technique and subsequent immersion in a ruthenium chloride solution allowed us to fabricate novel-concept microstructured catalysts. The paper-structured catalysts possess micropores ca. 30 μm in diameter with high porosity of ca. 90%. They exhibited much higher catalytic efficiency in the O2-mediated oxidation in toluene of benzyl alcohol to benzaldehyde in a fixed bed external loop reactor, as compared with conventional pellet- and bead-type solid catalysts. This excellent catalytic effect is possibly attributed to the porous paper composite microstructure like microreactors

  12. Efficient Catalytic Ozonation over Reduced Graphene Oxide for p-Hydroxylbenzoic Acid (PHBA) Destruction: Active Site and Mechanism.

    Science.gov (United States)

    Wang, Yuxian; Xie, Yongbing; Sun, Hongqi; Xiao, Jiadong; Cao, Hongbin; Wang, Shaobin

    2016-04-20

    Nanocarbons have been demonstrated as promising environmentally benign catalysts for advanced oxidation processes (AOPs) upgrading metal-based materials. In this study, reduced graphene oxide (rGO) with a low level of structural defects was synthesized via a scalable method for catalytic ozonation of p-hydroxylbenzoic acid (PHBA). Metal-free rGO materials were found to exhibit a superior activity in activating ozone for catalytic oxidation of organic phenolics. The electron-rich carbonyl groups were identified as the active sites for the catalytic reaction. Electron spin resonance (ESR) and radical competition tests revealed that superoxide radical ((•)O2(-)) and singlet oxygen ((1)O2) were the reactive oxygen species (ROS) for PHBA degradation. The intermediates and the degradation pathways were illustrated from mass spectroscopy. It was interesting to observe that addition of NaCl could enhance both ozonation and catalytic ozonation efficiencies and make ·O2(-) as the dominant ROS. Stability of the catalysts was also evaluated by the successive tests. Loss of specific surface area and changes in the surface chemistry were suggested to be responsible for catalyst deactivation. PMID:27007603

  13. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    OpenAIRE

    Kabljanac, Ž.; Herjavec, I.; Mikoč, K.; Vdović, D.; Ljubičić, M.; Zečević, N.

    2011-01-01

    This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comp...

  14. Solid state and catalytic CO oxidation studies on Zn1-xNixMnO3 system

    International Nuclear Information System (INIS)

    Nickel-substituted zinc manganite compositions Zn1-xNixMnO3 (x = 0.0, 0.2, 0.4. 0.6, 0.8 and 1.0) with perovskite structure were prepared by co-precipitation precursor method and characterized by X-ray diffraction, infrared spectroscopy, atomic absorption spectroscopy, surface area measurement and thermal techniques. These compounds were tested for the model catalytic reaction of carbon monoxide oxidation. Attempts were made to correlate the solid state and spectroscopic studies of the compositions with their catalytic activities

  15. Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

    OpenAIRE

    Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram; Nachtegaal, Maarten; Grunwaldt, Jan-Dierk

    2012-01-01

    Pd/Al2O3 catalysts oscillate between ignition and extinction of the catalytic partial oxidation of methane when they are exposed to a 2:1 reaction mixture of methane and oxygen. The oscillations of the catalytic performance and the structure of Pd/Al2O3 catalysts in a fixed-bed reactor were investigated using spatially and time-resolved in situ quick scanning X-ray absorption spectroscopy with online mass spectrometry. The dynamic methane conversion oscillated between an inactive state, where...

  16. Reaction Mechanism for the Formation of Nitrogen Oxides (NO x ) During Coke Oxidation in Fluidized Catalytic Cracking Units

    KAUST Repository

    Chaparala, Sree Vidya

    2015-06-11

    Fluidized catalytic cracking (FCC) units in refineries process heavy feedstock obtained from crude oil distillation. While cracking feed, catalysts get deactivated due to coke deposition. During catalyst regeneration by burning coke in air, nitrogen oxides (NOx) are formed. The increase in nitrogen content in feed over time has resulted in increased NOx emissions. To predict NOx concentration in flue gas, a reliable model for FCC regenerators is needed that requires comprehensive understanding and accurate kinetics for NOx formation. Based on the nitrogen-containing functional groups on coke, model molecules are selected to study reactions between coke-bound nitrogen and O2 to form NO and NO2 using density functional theory. The reaction kinetics for the proposed pathways are evaluated using transition state theory. It is observed that the addition of O2 on coke is favored only when the free radical is present on the carbon atom instead of nitrogen atom. Thus, NOx formation during coke oxidation does not result from the direct attack by O2 on N atoms of coke, but from the transfer of an O atom to N from a neighboring site. The low activation energies required for NO formation indicate that it is more likely to form than NO2 during coke oxidation. The favorable pathways for NOx formation that can be used in FCC models are identified. Copyright © 2015 Taylor & Francis Group, LLC.

  17. Kinetic modeling of ethylbenzene dehydrogenation over hydrotalcite catalysts

    KAUST Repository

    Atanda, Luqman

    2011-07-01

    Kinetics of ethylbenzene dehydrogenation to styrene was investigated over a series of quaternary mixed oxides of Mg3Fe0.25Me0.25Al0.5 (Me=Co, Mn and Ni) catalysts prepared by calcination of hydrotalcite-like compounds and compared with commercial catalyst. The study was carried out in the absence of steam using a riser simulator at 400, 450, 500 and 550°C for reaction times of 5, 10, 15 and 20s. Mg3Fe0.25Mn0.25Al0.5 afforded the highest ethylbenzene conversion of 19.7% at 550°C. Kinetic parameters for the dehydrogenation process were determined using the catalyst deactivation function based on reactant conversion model. The apparent activation energies for styrene production were found to decrease as follows: E1-Ni>E1-Co>E1-Mn. © 2011 Elsevier B.V.

  18. Influence of the physico-chemical properties of CeO2-ZrO2 mixed oxides on the catalytic oxidation of NO to NO2

    International Nuclear Information System (INIS)

    Commercial and home-made Ce-Zr catalysts prepared by co-precipitation were characterised by XRD, Raman spectroscopy, N2 adsorption at -196 deg. C and XPS, and were tested for NO oxidation to NO2. Among the different physico-chemical properties characterised, the surface composition seems to be the most relevant one in order to explain the NO oxidation capacity of these Ce-Zr catalysts. As a general trend, Ce-Zr catalysts with a cerium-rich surface, that is, high XPS-measured Ce/Zr atomic surface ratios, are more active than those with a Zr-enriched surface. The decrease in catalytic activity of the Ce-Zr mixed oxided upon calcinations at 800 deg. C with regard to 500 deg. C is mainly attributed to the decrease in Ce/Zr surface ratio, that is, to the surface segregation of Zr. The phase composition (cubic or t'' for Ce-rich compositions) seems not to be a direct effect on the catalytic activity for NO oxidation in the range of compositions tested. However, the formation of a proper solid solution prevents important surface segregation of Zr upon calcinations at high temperature. The effect of the BET surface area in the catalytic activity for NO oxidation of Ce-Zr mixed oxides is minor in comparison with the effect of the Ce/Zr surface ratio.

  19. Catalytic cracking of vegetable oil with metal oxides for biofuel production

    International Nuclear Information System (INIS)

    Highlights: • Biofuel was synthesized from vegetable oil by catalytic cracking. • Performance of six different metal catalysts was studied. • Influence of temperature and reaction time on the process was evaluated. • Methyl and ethyl esters are the major components of the biofuel synthesized. - Abstract: This study presents the utilization of metal oxides for the biofuel production from vegetable oil. The physical and chemical properties of the diesel-like products obtained, and the influence of reaction variables on the product distribution were investigated. Six different metal oxides (Co3O4, KOH, MoO3, NiO, V2O5, and ZnO) were employed as catalysts and the results indicated that the metal oxides are suitable for catalyzing the conversion of oil into organic liquid products (OLPs). The maximum conversion (87.6%) was obtained with V2O5 at 320 °C in 40 min whereas a minimum conversion (55.1%) was obtained with MoO3 at 390 °C in 30 min. The physical characteristics of the product obtained (density, specific gravity, higher heat value, flash point and kinematic viscosity), were in line with ASTM D6751 (B100) standards. The hydrocarbons majorly present in the product were found to be methyl and ethyl esters. Furthermore, OLPs obtained were distilled and separated into four components. The amount of light hydrocarbons, gasoline, kerosene and heavy oil like components obtained were 18.73%, 33.62%, 24.91% and 90.93%, respectively

  20. A broad spectrum catalytic system for removal of toxic organics from water by deep oxidation. 1998 annual progress report

    International Nuclear Information System (INIS)

    'Toxic organics and polymers pose a serious threat to the environment, especially when they are present in aquatic systems. The objective of the research is the design of practical procedures for the removal and/or recycling of such pollutants by oxidation. This report summarizes the work performed in the first one and half years of a three year project. The authors had earlier described a catalytic system for the deep oxidation of toxic organics, such as benzene, phenol and substituted phenols, aliphatic and aromatic halogenated compounds, organophosphorus, and organosulfur compounds [1]. In this system, metallic palladium was found to catalyze the oxidation of the substrate by dioxygen in aqueous medium at 80--100 C in the presence of carbon monoxide. For all the substrates examined, deep oxidation to carbon monoxide, carbon dioxide, and water occurred in high yields, resulting in up to several hundred turnovers over a 24 h period. Because of a pressing need for new procedures for the destruction of chemical warfare agents, the authors have examined in detail the deep oxidation of appropriate model compounds containing phosphorus-carbon and sulfur-carbon bonds using the same catalytic system. The result is the first observation of the efficient catalytic oxidative cleavage of phosphorus-carbon and sulfur-carbon bonds under mild conditions, using dioxygen as the oxidant [2]. In addition to the achievements described above, they have unpublished results in several other areas. For example, they have investigated the possibility of using dihydrogen rather than carbon monoxide as a coreductant in the catalytic deep oxidation of substrates. Even more attractive from a practical standpoint is the possibility of using a mixture of carbon monoxide and dihydrogen (synthesis gas). Indeed, experiments indicated that it is possible to substitute carbon monoxide by dihydrogen or synthesis gas. Significantly, in the case of nitro compounds, the deep oxidation in fact proceeded