Modification by SiO2 of Alumina Support for Light Alkane Dehydrogenation Catalysts

Directory of Open Access Journals (Sweden)

Giyjaz E. Bekmukhamedov

2016-10-01

Full Text Available Due to the continuously rising demand for C3–C5 olefins it is important to improve the performance of catalysts for dehydrogenation of light alkanes. In this work the effect of modification by SiO2 on the properties of the alumina support and the chromia-alumina catalyst was studied. SiO2 was introduced by impregnation of the support with a silica sol. To characterize the supports and the catalysts the following techniques were used: low-temperature nitrogen adsorption; IR-spectroscopy; magic angle spinning 29Si nuclear magnetic resonance; temperature programmed desorption and reduction; UV-Vis-, Raman- and electron paramagnetic resonance (EPR-spectroscopy. It was shown that the modifier in amounts of 2.5–7.5 wt % distributed on the support surface in the form of SiOx-islands diminishes the interaction between the alumina support and the chromate ions (precursor of the active component. As a result, polychromates are the compounds predominantly stabilized on the surface of the modified support; under thermal activation of the catalyst and are reduced to the amorphous Cr2O3. This in turn leads to an increase in the activity of the catalyst in the dehydrogenation of isobutane.

Wet chemical synthesis of nickel supported on alumina catalysts; Sintese de catalisadores de niquel suportado em alumina por via umida

Energy Technology Data Exchange (ETDEWEB)

Freire, Ranny Rodrigues; Costa, Talita Kenya Oliveira; Morais, Ana Carla da Fonseca Ferreira; Costa, Ana Cristina Figueiredo de Melo; Freitas, Normanda Lino de, E-mail: normanda@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

2016-07-01

Heterogenic catalysts are those found to be in a different phase on the reaction when compared to the reactants and products. Preferred when compared to homogeneous catalysts due to the easiness on which the separation is processed. The objective of this study is to obtain and characterize Alumina based catalysts impregnated with Nickel (Al{sub 2}O{sub 3}), by wet impregnation. The alumina was synthesized by combustion reaction. Before and after the impregnation the catalysts were characterized by X-ray diffraction (XRD), granulometric analysis, the textural analysis will be held by nitrogen adsorption (BET), energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). The results show a presence of a stable crystalline phase of Al2O3 in all the studied samples and after the impregnation the second phase formed was of NiO and NiAl{sub 2}O{sub 4}. The Al{sub 2}O{sub 3} e Ni/Al{sub 2}O{sub 3} catalysts resulted in clusters with a medium diameter of 18.9 and 14.2 μm, respectively. The catalysts show a medium-pore characteristic (medium pore diameter between 2 and 50 nm), the superficial area to Al{sub 2}O{sub 3} and Ni/Al{sub 2}O{sub 3} catalysts were 8.69 m{sup 2}/g and 5.56 m{sup 2}/g, respectively. (author)

Hydrogen production by steam reforming of liquefied natural gas over a nickel catalyst supported on mesoporous alumina xerogel

Science.gov (United States)

Seo, Jeong Gil; Youn, Min Hye; Cho, Kyung Min; Park, Sunyoung; Song, In Kyu

Mesoporous alumina xerogel (A-SG) is prepared by a sol-gel method for use as a support for a nickel catalyst. The Ni/A-SG catalyst is then prepared by an impregnation method, and is applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of the mesoporous alumina xerogel support on the catalytic performance of Ni/A-SG catalyst is investigated. For the purpose of comparison, a nickel catalyst supported on commercial alumina (A-C) is also prepared by an impregnation method (Ni/A-C). Both the hydroxyl-rich surface and the electron-deficient sites of the A-SG support enhance the dispersion of the nickel species on the support during the calcination step. The formation of the surface nickel aluminate phase in the Ni/A-SG catalyst remarkably increases the reducibility and stability of the catalyst. Furthermore, the high-surface area and the well-developed mesoporosity of the Ni/A-SG catalyst enhance the gasification of surface hydrocarbons that are adsorbed in the reaction. In the steam reforming of LNG, the Ni/A-SG catalyst exhibits a better catalytic performance than the Ni/A-C catalyst in terms of LNG conversion and hydrogen production. Moreover, the Ni/A-SG catalyst shows strong resistance toward catalyst deactivation.

Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports.

Science.gov (United States)

Yaakob, Zahira; Bshish, Ahmed; Ebshish, Ali; Tasirin, Siti Masrinda; Alhasan, Fatah H

2013-05-30

Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/Al S.G. ) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/Al S.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/Al S.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.

Mesoporous silica materials modified with alumina polycations as catalysts for the synthesis of dimethyl ether from methanol

Energy Technology Data Exchange (ETDEWEB)

Macina, Daniel; Piwowarska, Zofia; Tarach, Karolina; Góra-Marek, Kinga [Jagiellonian University, Faculty of Chemistry, Ingardena 3, 30-060 Kraków (Poland); Ryczkowski, Janusz [Maria Curie Skłodowska University, Faculty of Chemistry, Maria Curie-Skłodowska 2, 20-031 Lublin (Poland); Chmielarz, Lucjan, E-mail: chmielar@chemia.uj.edu.pl [Jagiellonian University, Faculty of Chemistry, Ingardena 3, 30-060 Kraków (Poland)

2016-02-15

Highlights: • Deposition of alumina ologoctaions on mesoporous silicas modified with surface −SO{sub 3}H groups. • Alumina aggregates generated acid properties in the silica supports. • Alumina modified SBA-15 and MCF were active and selective catalysts in DME synthesis. - Abstract: Mesoporous silica materials (SBA-15 and MCF) were used as catalytic supports for the deposition of aggregated alumina species using the method consisting of the following steps: (i) anchoring 3-(mercaptopropyl)trimethoxysilane (MPTMS) on the silica surface followed by (ii) oxidation of −SH to−SO{sub 3}H groups and then (iii) deposition of aluminum Keggin oligocations by ion-exchange method and (iv) calcination. The obtained samples were tested as catalysts for synthesis of dimethyl ether from methanol. The modified silicas were characterized with respect to the ordering of their porous structure (XRD), textural properties (BET), chemical composition (EDS, CHNS), structure ({sup 27}Al NMR, FTIR) and location of alumina species (EDX-TEM), surface acidity (NH{sub 3}-TPD, Py-FTIR) and thermal stability (TGA). The obtained materials were found to be active and selective catalysts for methanol dehydration to dimethyl ether (DME) in the MTD process (methanol-to-dimethyl ether).

Desorption of Furfural from Bimetallic Pt-Fe Oxides/Alumina Catalysts

Directory of Open Access Journals (Sweden)

Gloria Lourdes Dimas-Rivera

2014-01-01

Full Text Available In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA. The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM imaging revealed the intimate connection between the iron and platinum oxide species on the alumina support. The mechanism of furfural desorption from the Pt-Fe/Al2O3 0.5%-0.5% sample was determined using physisorbed furfural instead of chemisorbed furfural; this mechanism involved the oxidation of the C=O group on furfural by the catalyst. The oxide nanoparticles on γ-Al2O3 support helped to stabilize the furfural molecule on the surface.

Synthesis and nature of heterogeneous catalysts of low-valent tungsten supported on alumina

Energy Technology Data Exchange (ETDEWEB)

Brenner, A.; Hucul, D.A.

1980-01-01

Temperature-programed decomposition of catalysts prepared from zero-valent W(CO)/sub 6/ and alumina under rigorously air-free conditions showed a low-temperature carbon monoxide desorption peak at 110/sup 0/-172/sup 0/C, depending on alumina pretreatment, in which a relatively stable surface W(CO)/sub 3/ complex was formed; and a high-temperature carbon monoxide desorption peak at 257/sup 0/ to > 400/sup 0/C, which gave zero-valent tungsten if the ratio of hydroxyl groups of alumina to tungsten surface complexes was low, and hexavalent tungsten if the ratio was high. Up to about half the W(CO)/sub 6/ sublimated from the alumina during activation.

Effect of Al content on the gas-phase dehydration of glycerol over silica-alumina-supported silicotungstic acid catalysts

International Nuclear Information System (INIS)

Kim, Yong Tae; You, Su Jin; Park, Eun Duck; Jung, Kwangdeog

2012-01-01

The gas-phase dehydration of glycerol to acrolein was carried out over silicotungstic acid (H 4 SiW 12 O 40 ·xH 2 O, HSiW) catalysts supported on SiO 2 , η-Al 2 O 3 , and silica-alumina with different Al contents. The HSiW catalysts supported on silica-alumina showed higher glycerol conversions and acrolein yields during the initial 2 h at 315.deg.C than did SiO 2 - and η-Al 2 O 3 -supported HSiW catalysts. Among the tested catalysts, HSiW/Si 0.9 Al 0.1Ox exhibited the highest space-time yield during the initial 2 h. The loaded HSiW species can change the acid types and suppress the formation of carbonaceous species on Al-rich silica-alumina. The deactivated HSiW supported on silica-alumina can be fully regenerated after calcination in air at 500.deg.C. As long as the molar ratio between water and glycerol was in the range of 2-11, the acrolein selectivity increased significantly with increasing water content in the feed, while the surface carbon content decreased owing to the suppression of heavy compounds

Ni Catalysts Supported on Modified Alumina for Diesel Steam Reforming

Directory of Open Access Journals (Sweden)

Antonios Tribalis

2016-01-01

Full Text Available Nickel catalysts are the most popular for steam reforming, however, they have a number of drawbacks, such as high propensity toward coke formation and intolerance to sulfur. In an effort to improve their behavior, a series of Ni-catalysts supported on pure and La-, Ba-, (La+Ba- and Ce-doped γ-alumina has been prepared. The doped supports and the catalysts have been extensively characterized. The catalysts performance was evaluated for steam reforming of n-hexadecane pure or doped with dibenzothiophene as surrogate for sulphur-free or commercial diesel, respectively. The undoped catalyst lost its activity after 1.5 h on stream. Doping of the support with La improved the initial catalyst activity. However, this catalyst was completely deactivated after 2 h on stream. Doping with Ba or La+Ba improved the stability of the catalysts. This improvement is attributed to the increase of the dispersion of the nickel phase, the decrease of the support acidity and the increase of Ni-phase reducibility. The best catalyst of the series doped with La+Ba proved to be sulphur tolerant and stable for more than 160 h on stream. Doping of the support with Ce also improved the catalytic performance of the corresponding catalyst, but more work is needed to explain this behavior.

Highly active Pd-In/mesoporous alumina catalyst for nitrate reduction.

Science.gov (United States)

Gao, Zhenwei; Zhang, Yonggang; Li, Deyi; Werth, Charles J; Zhang, Yalei; Zhou, Xuefei

2015-04-09

The catalytic reduction of nitrate is a promising technology for groundwater purification because it transforms nitrate into nitrogen and water. Recent studies have mainly focused on new catalysts with higher activities for the reduction of nitrate. Consequently, metal nanoparticles supported on mesoporous metal oxides have become a major research direction. However, the complex surface chemistry and porous structures of mesoporous metal oxides lead to a non-uniform distribution of metal nanoparticles, thereby resulting in a low catalytic efficiency. In this paper, a method for synthesizing the sustainable nitrate reduction catalyst Pd-In/Al2O3 with a dimensional structure is introduced. The TEM results indicated that Pd and In nanoparticles could efficiently disperse into the mesopores of the alumina. At room temperature in CO2-buffered water and under continuous H2 as the electron donor, the synthesized material (4.9 wt% Pd) was the most active at a Pd-In ratio of 4, with a first-order rate constant (k(obs) = 0.241 L min(-1) g(cata)(-1)) that was 1.3× higher than that of conventional Pd-In/Al2O3 (5 wt% Pd; 0.19 L min(-1) g(cata)(-1)). The Pd-In/mesoporous alumina is a promising catalyst for improving the catalytic reduction of nitrate. Copyright © 2015 Elsevier B.V. All rights reserved.

Studies on the promotion of nickel—alumina coprecipitated catalysts: III. Cerium oxide

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Slaa, J.C.; van Ommen, J.G.; Ross, J.R.H.

1988-01-01

Three series of cerium-promoted nickel—alumina catalysts with different nickel-to-aluminium ratios each containing different amounts of cerium have been prepared and characterized. The calcination and reduction behaviour were found not to be altered by the presence of cerium. Part of the promoter

HDS, HDN and HDA activities of nickel-molybdenum catalysts supported on alumina

Energy Technology Data Exchange (ETDEWEB)

Dominguez-Crespo, M.A. [Instituto Mexicano del Petroleo, Programa de Tratamiento de Crudo Maya. Avenida Eje Central Lazaro Cardenas No.152, Col. San Bartolo Atepehuacan, 07730, Mexico D. F. (Mexico); Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (CICATA-Altamira, IPN) Km 14.5 Carretera Tampico-puerto Industrial 89600, Altamira, Tamaulipas (Mexico); Torres-Huerta, A.M.; Ramirez-Meneses, E. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (CICATA-Altamira, IPN) Km 14.5 Carretera Tampico-puerto Industrial 89600, Altamira, Tamaulipas (Mexico); Diaz-Garcia, L. [Instituto Mexicano del Petroleo, Programa de Tratamiento de Crudo Maya. Avenida Eje Central Lazaro Cardenas No.152, Col. San Bartolo Atepehuacan, 07730, Mexico D. F. (Mexico); Arce-Estrada, E.M. [Instituto Politecnico Nacional, Departamento de Metalurgia y Materiales. A.P. 75-876, 07300 Mexico, D. F. (Mexico)

2008-08-15

In this work, NiMo-Al{sub 2}O{sub 3} catalysts were prepared by using different alumina precursors. The supports were impregnated by means of the spray at incipient wetness technique in both basic and acid media. Both the supports and fresh catalysts were characterized by the adsorption-desorption isotherms, Temperature-Programmed Reduction (TPR), Thermal Pyridine Adsorption-Desorption (TPD) and X-Ray Diffraction analyses (XRD). After sulfidation, the NiMoS metallic particles were characterized by Transmission Electron Microscopy (TEM). The initial analyses were performed in a trickle-bed reactor by using a real feedstock (Mexican heavy gas oil) and performing hydrotreating reactions (HDS, HDN and HDA) at three different temperatures: 613, 633 and 653 K; and 54 kg cm{sup -} {sup 2}. The catalytic activities are discussed in relation to the physicochemical properties of the NiMo catalysts, alumina phase and pH of the impregnating solution. The catalytic results show an increase in the conversion profiles with temperature. The sulfur conversion was increased from 89 to 99.25%, 91-99%, 90.8-97%, 83-95% and 78-96% when the crystal size of the support varied from 3 to 20 nm, respectively. The nitrogen and aromatic conversions were also increased in the range of 23-45 wt.%. It was found that the {gamma} phase reached a higher catalytic performance than the {eta} phase. The NiMo catalysts synthesized in a basic medium showed a better catalytic performance than that obtained with those prepared in acid solutions. The significance of the kinetic data to compare the catalysts is discussed. The maximum value of the catalytic activity was reached with the catalysts with the smallest particle sizes. (author)

De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts

Directory of Open Access Journals (Sweden)

R.Y. Raskar

2012-06-01

Full Text Available The de-oxygenation of CO2 was explored by using hydrogen, methane, carbon etc., over alumina supported catalysts. The alumina-supported ruthenium, rhodium, platinum, molybdenum, vanadium and magnesium catalysts were first reduced in hydrogen atmosphere and then used for the de-oxygenation of CO2. Furthermore, experimental variables for the de-oxygenation of CO2 were temperature (range 50 to 650 oC, H2/CO2 mole ratios (1.0 to 5, and catalyst loading (0.5 to 10 wt %. During the de-oxygenation of CO2 with H2 or CH4 or carbon, conversion of CO2, selectivity to CO and CH4 were estimated. Moreover, 25.4 % conversion of CO2 by hydrogen was observed over 1 wt% Pt/Al2O3 catalyst at 650 oC with 33.8 % selectivity to CH4. However, 8.1 to 13.9 % conversion of CO2 was observed over 1 wt% Pt/Al2O3 catalyst at 550 oC in the presence of both H2 and CH4. Moreover, 42.8 to 79.4 % CH4 was converted with 9 to 23.1 % selectivity to CO. It was observed that the de-oxygenation of CO2 by hydrogen, carbon and methane produced carbon, CO and CH4. © 2012 BCREC UNDIP. All rights reservedReceived: 6th February 2012; Revised: 23rd April 2012; Accepted: 24th April 2012[How to Cite: R. Y. Raskar, K. B. Kale, A. G. Gaikwad. (2011. De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 59-69.  doi:10.9767/bcrec.7.1.1631.59-69][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1631.59-69 ] | View in 

Studies on the promotion of nickel—alumina coprecipitated catalysts: II. Lanthanum oxide

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Paalman, R.P.A.M.; van Ommen, J.G.; Ross, J.R.H.

1988-01-01

Two series of lanthanum promoted nickel—alumina catalysts have been prepared by coprecipitation of the metal nitrates, using potassium carbonate. The molar ratio between nickel and the sum of aluminium and lanthanum was kept constant at 2.5 or 9.0 within each series. The calcination and reduction of

Quantitative positron annihilation studies in citrates, halides and oxyhalides chemisorbed on γ-alumina catalyst

International Nuclear Information System (INIS)

Luo, X.H.; Jean, Y.C.; Cheng, K.L.

1987-01-01

A quantitative study of the γ-alumina catalyst chemisorbed by nitrates, halides, and oxyhalides has been conducted with the positron annihilation spectroscopy (PAS). Catalysts containing Fe, Co, or Ni have been extensively used in chemical industry and petroleum refining. The positron or Ps annihilation can provide a profile information about the bulk, near surface, and void. It is an in-situ surface technique. The PAS technique has shown its capability to determine the nitrate or chloride in γ-alumina as low as 0.02% in solids. It is interesting to note that the PAS may offer the oxidation state information in solids. This is not surprising because the positron annihilation is sensitive to the electron density variation in environments. Positron annihilation models for halides and oxyhalides are proposed

Biogasoline Production from Palm Oil Via Catalytic Hydrocracking over Gamma-Alumina Catalyst

Directory of Open Access Journals (Sweden)

Anondho Wijanarko

2010-10-01

Full Text Available Bio gasoline conversion from palm oil is an alternative energy resources method which can be substituted fossil fuel base energy utilization. Previous research resulted that palm oil can be converted into hydrocarbon by catalytic cracking reaction with γ-alumina catalyst. In this research, catalytic cracking reaction of palm oil by γ-alumina catalyst is done in  a stirrer batch reactor with the oil/catalyst weight ratio variation of 100:1, 75:1, and 50:1; at suhue variation of 260 to 340oC and reaction time variation of 1 to 2 hour. Post cracking reaction, bio gasoline yield could be obtained after 2 steps batch distillation. Physical property test result such as density and viscosity of this cracking reaction product and commercial gasoline tended a closed similarity. According to result of the cracking product's density, viscosity and FTIR, it  can conclude that optimum yield of the palm oil catalytic cracking reaction could be occurred when oil/catalyst weight  ratio 100:1 at 340 oC in 1.5 hour and base on this bio gasoline's FTIR, GC and GC-MS identification results, its  hydrocarbons content was resembled to the commercial  gasoline. This palm oil catalytic cracking reaction shown 11.8% (v/v in yield and 28.0% (v/v in conversion concern to feed palm oil base and produced a 61.0 octane number's biogasoline.

Control of porosity in alumina for catalytic purposes - a review; Controle de porosidade em aluminas para fins cataliticos - uma revisao

Energy Technology Data Exchange (ETDEWEB)

Moure, Gustavo Torres [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Setor de Tecnologia de Hidrorrefino, Lubrificantes e Parafinas; Morgado Junior, Edisson [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Setor de Tecnologia de Craqueamento Catalitico; Figueiredo, Cecilia Maria C.

1999-12-01

In recent years, the Alumina Group, of the Catalysts Division of CENPES, has dedicated research to develop and characterize alumina for the catalytic processes of interest to PETROBRAS. Control of the texture of the alumina and, consequently, the alumina based catalysts, is crucially important to their adequacy and performance. Knowledge of the porosity formation mechanisms in alumina was fundamental for the development of catalysts to satisfy the demand from PETROBRAS. This comprises the scope of this review. (author)

Selective nano alumina supported vanadium oxide catalysts for oxidative dehydrogenation of ethylbenzene to styrene using CO2 as soft oxidant

Directory of Open Access Journals (Sweden)

A.M. Elfadly

2013-12-01

Full Text Available Nano alumina-supported V2O5 catalysts with different loadings have been tested for the dehydrogenation of ethylbenzene with CO2 as an oxidant. High surface area nano-alumina was prepared and used as support for V2O5 as the catalyst. The catalysts were synthesized by impregnation techniques followed by calcinations and microwave treatment, denoted as V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW, respectively. The V2O5 loading was varied on nano-alumina from 5 to 30 wt%. The support and catalysts were characterized by X-ray diffraction (XRD, Barett–Joyner–Halenda (BJH pore-size distribution, N2-adsorption isotherms, Fourier transform infrared (FT-IR, scanning electron microscopy (SEM, transmission electron microscopy (TEM and temperature programed desorption (TPD-NH3. The characterization results indicated that V2O5 is highly dispersed on alumina up to 30%-V2O5/γ-Al2O3-MW prepared by MW method. The TPD studies indicated that there are significant differences in acid amount and strength for V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW-catalysts. The catalytic activity of the prepared catalysts was evaluated in the temperature range 450–600 °C in relation to the physicochemical properties and surface acidity. The results revealed that optimum catalytic activity and selectivity (∼100% toward styrene production were obtained using 10% V2O5/γ-Al2O3-MW catalyst treated with microwave.

An anodic alumina supported Ni-Pt bimetallic plate-type catalysts for multi-reforming of methane, kerosene and ethanol

KAUST Repository

Zhou, Lu

2014-05-01

An anodic alumina supported Ni-Pt bimetallic plate-type catalyst was prepared by a two-step impregnation method. The trace amount 0.08 wt% of Pt doping efficiently suppressed the nickel particle sintering and improved the nickel oxides reducibility. The prepared Ni-Pt catalyst showed excellent performance during steam reforming of methane, kerosene and ethanol under both 3000 h stationary and 500-time daily start-up and shut-down operation modes. Self-activation ability of this catalyst was evidenced, which was considered to be resulted from the hydrogen spillover effect over Ni-Pt alloy. In addition, an integrated combustion-reforming reactor was proposed in this study. However, the sintering of the alumina support is still a critical issue for the industrialization of Ni-Pt catalyst. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Aliphatic Hydrocarbons from Lignocellulose by Pyrolysis over Cesium-Modified Amorphous Silica Alumina Catalysts

NARCIS (Netherlands)

Zabeti, M.; Sai Sankar Gupta, Karthick Babu; Raman, G.; Lefferts, Leon; Schallmoser, Stefan; Lercher, Johannes A.; Seshan, K.

2015-01-01

Cesium-modified amorphous silica alumina (Cs/ASA) is a promising catalyst for the production of hydrocarbons through pyrolysis of biomass. Catalytic pyrolysis of pinewood over Cs/ASA in a pyrolyzer system in conjunction with a gas chromatograph and mass spectrometer resulted in a 22% yield of

Low Concentration Fe-Doped Alumina Catalysts Using Sol-Gel and Impregnation Methods: The Synthesis, Characterization and Catalytic Performance during the Combustion of Trichloroethylene

Directory of Open Access Journals (Sweden)

Carolina Solis Maldonado

2014-03-01

Full Text Available The role of iron in two modes of integration into alumina catalysts was studied at 0.39 wt% Fe and tested in trichloroethylene combustion. One modified alumina was synthesized using the sol-gel method with Fe added in situ during hydrolysis; another modification was performed using calcined alumina, prepared using the sol-gel method and impregnated with Fe. Several characterization techniques were used to study the level of Fe modification in the γ-Al2O3 phase formed and to correlate the catalytic properties during trichloroethylene (TCE combustion. The introduction of Fe in situ during the sol-gel process influenced the crystallite size, and three iron species were generated, namely, magnetite, maghemite and hematite. The impregnated Fe-alumina formed hematite and maghemite, which were highly dispersed on the γ-Al2O3 surface. The X-ray photoelectron spectra (XPS, FT-IR and Mössbauer spectroscopy analyses revealed how Fe interacted with the γ-Al2O3 lattice in both catalysts. The impregnated Fe-catalyst showed the best catalytic performance compared to the catalyst that was Fe-doped in situ by the sol-gel method; both had better catalytic activity than pure alumina. This difference in activity was correlated with the accessibility of the reactants to the hematite iron species on the surface. The chlorine poisoning for all three catalysts was less than 1.8%.

Low Concentration Fe-Doped Alumina Catalysts Using Sol-Gel and Impregnation Methods: The Synthesis, Characterization and Catalytic Performance during the Combustion of Trichloroethylene.

Science.gov (United States)

Maldonado, Carolina Solis; De la Rosa, Javier Rivera; Lucio-Ortiz, Carlos J; Hernández-Ramírez, Aracely; Barraza, Felipe F Castillón; Valente, Jaime S

2014-03-12

The role of iron in two modes of integration into alumina catalysts was studied at 0.39 wt% Fe and tested in trichloroethylene combustion. One modified alumina was synthesized using the sol-gel method with Fe added in situ during hydrolysis; another modification was performed using calcined alumina, prepared using the sol-gel method and impregnated with Fe. Several characterization techniques were used to study the level of Fe modification in the γ-Al₂O₃ phase formed and to correlate the catalytic properties during trichloroethylene (TCE) combustion. The introduction of Fe in situ during the sol-gel process influenced the crystallite size, and three iron species were generated, namely, magnetite, maghemite and hematite. The impregnated Fe-alumina formed hematite and maghemite, which were highly dispersed on the γ-Al₂O 3 surface. The X-ray photoelectron spectra (XPS), FT-IR and Mössbauer spectroscopy analyses revealed how Fe interacted with the γ-Al₂O₃ lattice in both catalysts. The impregnated Fe-catalyst showed the best catalytic performance compared to the catalyst that was Fe-doped in situ by the sol-gel method; both had better catalytic activity than pure alumina. This difference in activity was correlated with the accessibility of the reactants to the hematite iron species on the surface. The chlorine poisoning for all three catalysts was less than 1.8%.

Secondary promoters in alumina-supported nickel-molybdenum hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Lewis, J.M.

1992-01-01

Two secondary promoters, phosphorus and fluoride, have been investigated for their influences on the physicochemical properties of alumina-supported nickel-molybdenum hydroprocessing catalysts. Model compound reactions and infrared spectroscopy were used to probe the functionalities of the different catalysts, and the catalysts were tested in the hydroprocessing of a low-nitrogen and a high-nitrogen (quinoline-spiked) gas oil feed to assess the utility of the model compound reaction studies. Fluoride-promoted catalysts with high cumene hydrocracking activity and with comparable thiophene hydrodesulphurization (HDS) activity to Ni-Mo/Al[sub 2]O[sub 3] can be prepared by coimpregnation of the F, Ni and Mo additives. Fluoride promotes the hydrogenation (HYD) and HDS activity of Ni-Mo/Al[sub 2]O[sub 3] in the hydroprocessing (HYD) and HDS activity of Ni-Mo/Al[sub 2]O[sub 3] in the hydroprocessing of a low-nitrogen feed. Fluoride promotes the quinoline hydrodenitrogenation (HDN) activity of Ni-Mo/Al[sub 2]O[sub 3] catalysts. Impregnation of phosphorus prior to the metal additives results in catalysts which are more active in HDS. Phosphorus increases indirectly the Broensted acidity of the catalyst by increasing the activity of the MoS[sub 2]-associated acid sites. Phosphorus promotes the HDSW and HYD activities of Ni-Mo/Al[sub 2]O[sub 3] in the hydroprocessing of the low-N feed. A promotional effect of phosphorus is seen in quinoline HDN. P- and F-promoted Ni-MO/Al[sub 2]O[sub 3] catalysts are very active in quinoline HDN and maintain good activity in HDS and HYD of the high-N feed. Thiophene HDS was a good reaction for probing the activity of catalysts in the HDS of sterically-unhindered molecules, but an inaccurate probe for the HDS of hindered compounds.

Transformation of Vegetable Oils into Hydrocarbons over Mesoporous-Alumina-Supported CoMo Catalysts

Czech Academy of Sciences Publication Activity Database

Kubička, D.; Šimáček, P.; Žilková, Naděžda

2009-01-01

Roč. 52, 1-2 (2009), s. 161-168 ISSN 1022-5528 Grant - others:GA MPO(CZ) FT-TA3/074 Institutional research plan: CEZ:AV0Z40400503 Keywords : organized mesoporous alumina * CoMo catalysts * hydrodeoxygenation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.379, year: 2009

The application of inelastic neutron scattering to investigate the steam reforming of methane over an alumina-supported nickel catalyst

International Nuclear Information System (INIS)

McFarlane, Andrew R.; Silverwood, Ian P.; Norris, Elizabeth L.; Ormerod, R. Mark; Frost, Christopher D.; Parker, Stewart F.; Lennon, David

2013-01-01

Highlights: • Inelastic neutron scattering has been used to investigate a Ni/alumina catalyst. • The extent of hydrogen retention by the catalyst has been determined. • Filamentous carbon is identified as a by-product. - Abstract: An alumina-supported nickel catalyst, previously used in methane reforming experiments employing CO 2 as the oxidant, is applied here in the steam reforming variant of the process. Micro-reactor experiments are used to discern an operational window compatible with sample cells designed for inelastic neutron scattering (INS) experiments. INS spectra are recorded after 6 h reaction of a 1:1 mixture of CH 4 and H 2 O at 898 K. Weak INS spectra are observed, indicating minimal hydrogen retention by the catalyst in this operational regime. Post-reaction, the catalyst is further characterised by powder X-ray diffraction, transmission electron microscopy and Raman scattering. In a comparable fashion to that seen for the ‘dry’ reforming experiments, the catalyst retains substantial quantities of carbon in the form of filamentous coke. The role for hydrogen incorporation by the catalyst is briefly considered

The application of inelastic neutron scattering to investigate the steam reforming of methane over an alumina-supported nickel catalyst

Energy Technology Data Exchange (ETDEWEB)

McFarlane, Andrew R.; Silverwood, Ian P. [School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Norris, Elizabeth L.; Ormerod, R. Mark [Department of Chemistry, School of Physical and Geographical Sciences, Keele University, Staffs ST5 5BG (United Kingdom); Frost, Christopher D.; Parker, Stewart F. [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Lennon, David, E-mail: David.Lennon@glasgow.ac.uk [School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2013-12-12

Highlights: • Inelastic neutron scattering has been used to investigate a Ni/alumina catalyst. • The extent of hydrogen retention by the catalyst has been determined. • Filamentous carbon is identified as a by-product. - Abstract: An alumina-supported nickel catalyst, previously used in methane reforming experiments employing CO{sub 2} as the oxidant, is applied here in the steam reforming variant of the process. Micro-reactor experiments are used to discern an operational window compatible with sample cells designed for inelastic neutron scattering (INS) experiments. INS spectra are recorded after 6 h reaction of a 1:1 mixture of CH{sub 4} and H{sub 2}O at 898 K. Weak INS spectra are observed, indicating minimal hydrogen retention by the catalyst in this operational regime. Post-reaction, the catalyst is further characterised by powder X-ray diffraction, transmission electron microscopy and Raman scattering. In a comparable fashion to that seen for the ‘dry’ reforming experiments, the catalyst retains substantial quantities of carbon in the form of filamentous coke. The role for hydrogen incorporation by the catalyst is briefly considered.

The nature of the potassium compound acting as a promoter in iron-alumina catalysts for ammonia synthesis

NARCIS (Netherlands)

van Ommen, J.G.; Bolink, W.J.; Prasad, J.; Mars, P.

1975-01-01

The chemical form of the potassium promoter on an iron-alumina catalyst during ammonia synthesis has been studied by two methods, viz, (i) the measurement of the equilibrium constant of the process KNH2 + H2 KH + NH3, and (ii) chemical analysis of the used catalyst. The equilibrium constant

Effect of Iridium Addition on the Reducibility of MoO3/Alumina Catalyst

Czech Academy of Sciences Publication Activity Database

Vít, Zdeněk; Cinibulk, Josef

2001-01-01

Roč. 72, č. 2 (2001), s. 189-194 ISSN 0304-4122 R&D Projects: GA AV ČR IAA4072802 Institutional research plan: CEZ:AV0Z4072921 Keywords : MoO3/alumina * MoIr catalyst * reducibility Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.514, year: 1999

{alpha}-Al{sub 2}O{sub 3} catalyst supports for synthesis gas production: influence of different alumina bonding agents on support and catalyst properties

Energy Technology Data Exchange (ETDEWEB)

Marturano, M. [Centro de Investigacion y Desarrollo en Procesos Cataliticos, La Plata (Argentina); Aglietti, E.F. [Centro de Tecnologia de Recursos Minerales y Ceramica (CETMIC), Gonnet (Argentina); Ferretti, O. [Centro de Investigacion y Desarrollo en Procesos Cataliticos, La Plata (Argentina)]|[Univ. Nacional de La Plata, Dept. de Ingenieria Quimica de la Facultad de Ingenieria, La Plata (Argentina)

1997-02-01

Aluminas are widely used as catalytic supports in chemical reactions. Reforming reactions to obtain synthesis gas requires good mechanical strength and low sintering behaviour. In this work, the influence of bentonite, aluminium phosphate and alumina gel as binder agents of a calcined {alpha}-Al{sub 2}O{sub 3} are analyzed with respect to support and catalytic properties. The {alpha}-Al{sub 2}O{sub 3} supports, calcined at 1300 C, are then impregnated with solutions of Ni and Al inorganic salts to obtain the catalysts and are finally tested in the reforming reaction of methane to synthesis gas at 500-900 C. Supports and catalysts are characterized by XRD, SEM, N{sub 2} adsorption, mechanical strength test and other techniques. Mechanical strength depends on the type and quantity of binder material used during support preparation. The influence of the support on the performance of the resulting catalyst is evidenced by means of catalytic tests. (orig.) 8 refs.

Characterization of catalysts by Moessbauer spectroscopy: An application to the study of Fischer-Tropsch, hydrotreating and super Claus catalysts

International Nuclear Information System (INIS)

Kraan, A.M. van der; Boellaard, E.; Craje, M.W.J.

1993-01-01

Moessbauer spectroscopy is an excellent in-situ technique for the identification of phases present in catalysts. Applied to metallic iron catalysts used in the Fischer-Tropsch reaction it reveals a detailed picture of the carburization process and provides insight into the relation between the properties of the catalytic material and its activity. The influence of a support and the effect of alloying iron with an (in)active metal on the catalytic performance is discussed for Fe, Cu-Fe and Ni-Fe systems. In addition, Moessbauer spectroscopy is used for the identification of 'Co-sulfide' species present in sulfided Co and CoMo catalysts applied in one of the largest chemical processes in the world, the hydrotreatment of crude oil. A structural model is proposed. Finally, the contribution of Moessbauer spectroscopic studies to the development of a new catalyst for cleaning of Claus tail gas via selective oxidation of hydrogen sulfide to elemental sulfur is discussed. (orig.)

Hydrogen Production by Steam Reforming of Natural Gas Over Vanadium-Nickel-Alumina Catalysts.

Science.gov (United States)

Yoo, Jaekyeong; Park, Seungwon; Song, Ji Hwan; Song, In Kyu

2018-09-01

A series of vanadium-nickel-alumina (xVNA) catalysts were prepared by a single-step sol-gel method with a variation of vanadium content (x, wt%) for use in the hydrogen production by steam reforming of natural gas. The effect of vanadium content on the physicochemical properties and catalytic activities of xVNA catalysts in the steam reforming of natural gas was investigated. It was found that natural gas conversion and hydrogen yield showed volcano-shaped trends with respect to vanadium content. It was also revealed that natural gas conversion and hydrogen yield increased with decreasing nickel crystallite size.

Kinetics and mechanistic study of n-alkane hydroisomerization reaction on Pt-doped γ-alumina catalyst

Directory of Open Access Journals (Sweden)

Abhishek Dhar

2017-12-01

Full Text Available The catalysts γ-alumina (GA, the reference catalyst and Pt doped γ-alumina (PGA-s were synthesized using a simple sol-gel technique, in which at first preparation of porous base (GA, then impregnation of platinum salt over the base and finally reduction of platinum in the surface of the support were done. These catalysts prepared in different mole ratios of Pt:Al as 2:1, 1:1 and 1:2 are named as PGA-1, PGA-2 and PGA-3 respectively. The isomerization of n-alkanes (n-hexane, n-heptane and n-octane were investigated over the synthesized catalysts. The 2-methyl pentane (2-MP, 2,2-dimethyl pentane (2,2-DMP and 2,3-dimethyl hexane (2,3-DMH are the major products of respective isomerization of n-hexane, n-heptane and n-octane, besides a small amount of other branched isomers are also produced. The product distribution is comparable to that reported for Pt based other catalysts. The optimal mole ratios of Pt:Al is 1:1 (PGA-2 gives quite good catalytic activity for isomerization of n-alkane. Even through in reusability study, PGA-2 gives better performance than others. We have mainly focused on kinetic study, reaction mechanism behind isomerization and calculated the order of reactions and activation energies of the isomerization reactions in the present work. Keywords: Isomerization, n-alkanes, Catalyst, Reaction mechanism, Kinetics study, Activation energy

Pyrolysis of plastic waste using alumina-pumice as catalyst

International Nuclear Information System (INIS)

Warnijati, S.; Agra, I.B.; Wibowo, W.

2000-01-01

Efforts to convert plastic waste to liquid fuel have been carried out, but the yield was not so promising yet. Various catalysts have been studied to drive the product more to the liquid fuel. In this study, alumina-pumice produced from cheap local materials, was used as catalyst. Solid polyethylene plastic waste was melted in a feed compartment surrounding the tube reactor, and the vapor flowed downward through the catalyst bed which was supported by small glass marbles. Air and water coolers were used to cool and condense the product. Liquid and uncondensable gas were collected in receivers and bottle filled with brine, respectively. The physical properties of a specific liquid product were tested according to the ASTM methods. Liquid and gas products increased with time and temperature, and the rate of liquid and gas formations followed first order reaction. Using 100 g of plastic waste and 40 g of catalyst, the favorable time and temperature of pyrolysis were 105 minutes and 653-673 K, respectively. Under this condition, 86 - 87 % of liquid, 45 - 53 mL/g of gas, and 1% of solid residue were obtained. The quantity of liquid product was higher than the previous work (which was just 70-75 %) and its physical properties were between those of kerosene and diesel oil. The gross heating value of the liquid was 49 796.03 J/g, and the gas burnt with yellow flame and some soot. (Author)

Evaluation of alumina-aluminium phosphate catalyst supports for hydrodenitrogenation of pyridine and coal-derived liquids

Energy Technology Data Exchange (ETDEWEB)

Menon, R.; Joo, H.S.; Guin, J.A.; Reucroft, P.J.; Kim, J.Y. [Auburn University, Auburn, AL (United States). Dept. of Chemical Engineering

1996-05-01

Several alumina-aluminum phosphate (AAP) catalyst supports were prepared by a coprecipitation method. Effect of variations in Al/P atomic ratios on support textural properties were examined. Finished NiMo/AAP catalysts containing nominally 3 wt% Ni and 13 wt% Mo were prepared by incipient wetness and characterized by several methods including elemental, BET, and XPS surface analysis. Initial hydrodenitrogenation (HDN) activities of the catalysts were examined in both pyridine model compound and coal liquid reactions. The AAP supports showed the opportunity to tailor the catalyst pore size by variation of the Al/P ratio. On a per unit surface areas basis, the AAP-supported catalysts had initial HDN activities comparable to those of a commercial P-promoted NiMo/Al{sub 2}O{sub 3} catalyst. Because of their unique textural properties, i.e. variable pore sizes, the AAP catalysts may offer advantages when dealing with macromolecular feedstocks where hindered diffusion may slow reaction rates. 37 refs., 8 figs., 6 tabs.

Platinum/ceria/alumina catalysts on microstructures for carbon monoxide conversion

Energy Technology Data Exchange (ETDEWEB)

Germani, G.; Schuurman, Y.; Mirodatos, C. [Institut de Recherches sur la Catalyse, CNRS, 2 Avenue Albert Einstein, 69626 Villeurbanne (France); Alphonse, P.; Courty, M. [CIRIMAT, UMR-CNRS 5085, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 04 (France)

2005-12-15

Platinum/ceria/alumina catalysts have been prepared by a sol-gel method and coated in the microchannels of stainless steel platelets. These catalysts are very active for the water-gas shift reaction between 300 and 400{sup o}C. Moreover, they are non-pyrophoric and thus well suited for the purification of hydrogen for PEM fuel cells. The obtained coatings show good adherence and catalytic activity. The influence of the amount of platinum and ceria as well as the effect of a binder on the catalytic performance has been investigated. The samples have been characterized before reaction by XRD, SEM and by N{sub 2} adsorption measurements. The kinetics, free from internal diffusion limitations, over these thin films have been described by a power law rate equation. An activation energy of 86kJ/mol has been found and at 260{sup o}C the TOF corresponds to 0.6+/-0.1s{sup -1} for all investigated samples. The superior activity of the platelets compared to the powder samples is attributed to the diffusion limitations inside the powder pellets. Thus catalysts deposited on microstructured platelets lead to a better platinum utilization.

Structured Ni catalysts on porous anodic alumina membranes for methane dry reforming: NiAl 2 O 4 formation and characterization

KAUST Repository

Zhou, Lu

2015-06-29

This communication presents the successful design of a structured catalyst based on porous anodic alumina membranes for methane dry reforming. The catalyst with a strong Ni-NiAl2O4 interaction shows both excellent activity and stability. This journal is © The Royal Society of Chemistry.

Structured Ni catalysts on porous anodic alumina membranes for methane dry reforming: NiAl 2 O 4 formation and characterization

KAUST Repository

Zhou, Lu; Guo, Y.; Basset, Jean-Marie; Kameyama, H.

2015-01-01

This communication presents the successful design of a structured catalyst based on porous anodic alumina membranes for methane dry reforming. The catalyst with a strong Ni-NiAl2O4 interaction shows both excellent activity and stability. This journal is © The Royal Society of Chemistry.

A comparison of alumina, carbon and carbon-covered alumina as support for Ni-Mo-F additives: gas oil hydroprocessing studies

Energy Technology Data Exchange (ETDEWEB)

Boorman, P.M.; Kydd, R.A.; Sorensen, T.S.; Chong, K.; Lewis, J.M.; Bell, W.S. (University of Calgary, Calgary, AB (Canada). Dept. of Chemistry)

1991-01-01

Catalysts with 3 wt% NiO, 15 wt% MoO{sub 3} and 0-6.9 nominal wt% fluoride supported on alumina, carbon and carbon-covered alumina were studied to examine the role of fluoride and the influence of the support on hydroprocessing on Alberta gas oil. Experiments were carried out in a batch reactor at 410{degree}C and 6.9 MPa initial H{sub 2} pressure. It was found that fluoride promotion enhances cracking and hydrogenation reactions resulting in decreased aromatic and sulphur contents in the gas oil. The promotion is dependent on the type of support and is related to the strength of the fluoride-support interaction and the accessibility of the fluoride to the surface hydroxyl groups on the support. A maximum in activity at 3.6 wt% fluoride was observed for the alumina-supported catalysts whereas higher loadings of fluoride were required for carbon-covered alumina-supported catalysts to see an improvement over their carbon-supported counterparts. However, the carbon-covered alumina-supported catalysts seem to have a lower propensity for coke deposition than their alumina counterparts. 27 refs., 1 fig., 4 tabs.

A comparison of alumina, carbon and carbon-covered alumina as supports for Ni-Mo-F additives: gas oil hydroprocessing studies

Energy Technology Data Exchange (ETDEWEB)

Boorman, P.M.; Kydd, R.A.; Sorensen, T.S.; Chong, K.; Lewis, J.M.; Bell, W.S. (Calgary Univ., AB (Canada). Dept. of Chemistry)

1992-01-01

Catalysts with 3 wt% NiO, 15 wt% MoO{sub 3} and 0-6.9 nominal wt% fluoride supported on alumina, carbon and carbon-covered alumina were studied to examine the role of fluoride and the influence of the support on hydroprocessing on Alberta gas oil. Experiments were carried out in a batch reactor at 410{sup o}C and 6.9 MPa initial H{sub 2} pressure. It was found that fluoride promotion enhances cracking and hydrogenation reactions resulting in decreased aromatic and sulphur contents in the gas oil. The promotion is dependent on the type of support and is related to the strength of the fluoride-support interaction and the accessibility of the fluoride to the surface hydroxyl groups on the support. A maximum in activity at 3.6 wt% fluoride was observed for the alumina-supported catalysts whereas higher loadings of fluoride were required for carbon-covered alumina-supported catalysts to see an improvement over their carbon supported counterparts. However, the carbon-covered alumina supported catalysts seem to have a lower propensity for coke deposition than their alumina counterparts. (author).

Determination of palladium content in palladium-alumina/palladium-silica/palladium-tin oxide catalyst for nuclear reactor applications

International Nuclear Information System (INIS)

Sharma, P.K.; Bassan, M.K.T.; Avhad, D.K.; Singhal, R.K.

2012-01-01

Alumina and silica act as support for finely divided palladium metal powder in synthesis of catalyst. These catalyst (Pd-Al 2 O 3 , Pd-SiO 2 and Pd-SnO 2 ) used in nuclear power reactor (moderator cover gas system) for the conversion of hydrogen. In Indian nuclear power programme these catalyst are regularly used in Kaiga 1 and 2 and Rajasthan atomic power plant 3 and 4. The performance of the catalyst, solely depends on the concentration of palladium, which is the active component in this catalyst composition. Therefore it is highly desirable to have rouged analytical methodology for the accurate estimation of palladium. Leaching of Pd from the bulk matrix is tedious due to the less reactive nature of Pd therefore complete solubilization of the matrix is carried out by fusion method

Controlled Oxygen Chemisorption on an Alumina Supported Rhodium Catalyst. The Formation of a New Metal-Metal Oxide Interface Determined with EXAFS.

NARCIS (Netherlands)

Koningsberger, D.C.; Martens, J.H.A.; Prins, R.

1989-01-01

An alumina-supported rhodium catalyst has been studied with EXAFS. After reduction and evacuation, oxygen was admitted at 100 and 300 K. EXAFS spectra of the catalyst after oxygen admission at 100 K indicated the beginning of oxidation. At 300 K only a small part of the rhodium particles remained

A comparative study of alumina-supported Ni catalysts prepared by photodeposition and impregnation methods on the catalytic ozonation of 2,4-dichlorophenoxyacetic acid

International Nuclear Information System (INIS)

Rodríguez, Julia L.; Valenzuela, Miguel A.; Tiznado, Hugo; Poznyak, Tatiana; Chairez, Isaac; Magallanes, Diana

2017-01-01

The heterogeneous catalytic ozonation on unsupported and supported oxides has been successfully tested for the removal of several refractory compounds in aqueous solution. In this work, alumina-supported nickel catalysts prepared by photodeposition and impregnation methods were compared in the catalytic ozonation of 2,4-dichlorophenoxyacetic acid (2,4-D). The catalysts were characterized by high-resolution electron microscopy and X-ray photoelectron spectroscopy. The photochemical decomposition of Ni acetylacetonate to produce Ni(OH) 2 , NiO, and traces of Ni° deposited on alumina was achieved in the presence of benzophenone as a sensitizer. A similar surface composition was found with the impregnated catalyst after its reduction with hydrogen at 500 °C and exposed to ambient air. Results indicated a higher initial activity and maleic acid (byproduct) concentration with the photodeposited catalyst (1 wt% Ni) compared to the impregnated catalyst (3 wt% Ni). These findings suggest the use of the photodeposition method as a simple and reliable procedure for the preparation of supported metal oxide/metal catalysts under mild operating conditions.

A comparative study of alumina-supported Ni catalysts prepared by photodeposition and impregnation methods on the catalytic ozonation of 2,4-dichlorophenoxyacetic acid

Energy Technology Data Exchange (ETDEWEB)

Rodríguez, Julia L., E-mail: ozliliana@yahoo.com.mx [Lab. Ing. Química Ambiental. ESIQIE–Instituto Politécnico Nacional (Mexico); Valenzuela, Miguel A. [Lab.Catálisis y Materiales. ESIQIE–Instituto Politécnico Nacional. Zacatenco (Mexico); Tiznado, Hugo [Centro de Nanociencias y Nanotecnología. CNyN Universidad Nacional Autónoma de México (Mexico); Poznyak, Tatiana [Lab. Ing. Química Ambiental. ESIQIE–Instituto Politécnico Nacional (Mexico); Chairez, Isaac [Departamento de Bioprocesos, UPIBI- Instituto Politécnico Nacional (Mexico); Magallanes, Diana [Lab. Ing. Química Ambiental. ESIQIE–Instituto Politécnico Nacional (Mexico)

2017-02-15

The heterogeneous catalytic ozonation on unsupported and supported oxides has been successfully tested for the removal of several refractory compounds in aqueous solution. In this work, alumina-supported nickel catalysts prepared by photodeposition and impregnation methods were compared in the catalytic ozonation of 2,4-dichlorophenoxyacetic acid (2,4-D). The catalysts were characterized by high-resolution electron microscopy and X-ray photoelectron spectroscopy. The photochemical decomposition of Ni acetylacetonate to produce Ni(OH){sub 2}, NiO, and traces of Ni° deposited on alumina was achieved in the presence of benzophenone as a sensitizer. A similar surface composition was found with the impregnated catalyst after its reduction with hydrogen at 500 °C and exposed to ambient air. Results indicated a higher initial activity and maleic acid (byproduct) concentration with the photodeposited catalyst (1 wt% Ni) compared to the impregnated catalyst (3 wt% Ni). These findings suggest the use of the photodeposition method as a simple and reliable procedure for the preparation of supported metal oxide/metal catalysts under mild operating conditions.

Oxidation of Propylene on catalytic Pt-Cu/y alumina. (Part I) Characterization of catalysts of Pt-Cu/y alumina for chemisorption of H2

International Nuclear Information System (INIS)

Carballo, Luis M; Zea, Hugo R

1999-01-01

In this work the effect of the composition of catalysts of Pt-Cu/y-alumina is analyzed on the superficial area it reactivates corresponding to the total oxidation of propylene. The experimental essays were also made in a differential reactor that was used so much for the characterization of the catalyst in situ by means of the measurement of the selective chemisorption of H 2 , the effects and the bimetallic interactions are discussed that frequently happen in the supported catalysts. Starting from the studies of chemical adsorption of H 2 on the supported catalysts of Pt-Cu was, by means of the application of the theory of the regular solution to the surface of the glasses and keeping in mind that the H 2 it adsorbs chemically only on the superficial atoms of Pt (it was observed that the hydrogen not it chemi-absorb on the Cu) that the Cu atoms are segregated to the surface of the bimetallic crystals

Effect of Support Pretreatment Temperature on the Performance of an Iron Fischer–Tropsch Catalyst Supported on Silica-Stabilized Alumina

Directory of Open Access Journals (Sweden)

Kamyar Keyvanloo

2018-02-01

Full Text Available The effect of support material pretreatment temperature, prior to adding the active phase and promoters, on Fischer–Tropsch activity and selectivity was explored. Four iron catalysts were prepared on silica-stabilized alumina (AlSi supports pretreated at 700 °C, 900 °C, 1100 °C or 1200 °C. Addition of 5% silica to alumina made the AlSi material hydrothermally stable, which enabled the unusually high support pretreatment temperatures (>900 °C to be studied. High-temperature dehydroxylation of the AlSi before impregnation greatly reduces FeO·Al2O3 surface spinel formation by removing most of the support-surface hydroxyl groups leading to more effectively carbided catalyst. The activity increases more than four-fold for the support calcined at elevated temperatures (1100–1200 °C compared with traditional support calcination temperatures of <900 °C. This unique pretreatment also facilitates the formation of ε′-Fe2.2C rather than χ-Fe2.5C on the AlSi support, which shows an excellent correlation with catalyst productivity.

Potassium Hydroxide Impregnated Alumina (KOH-Alumina) as a Recyclable Catalyst for the Solvent-Free Multicomponent Synthesis of Highly Functionalized Substituted Pyridazines and/or Substituted Pyridazin-3(2H)-ones under Microwave Irradiation.

Science.gov (United States)

Mecadon, Hormi; Myrboh, Bekington

2011-01-01

The work described herein employs potassium hydroxide impregnated alumina (KOH-alumina) as a mild, efficient, and recyclable catalyst for a one-pot solvent-free and environmentally safer synthesis of 3,4,6-triarylpyridazines and some substituted pyridazines from active methylene carbonyl species, 1,2-dicarbonyls, and hydrazine hydrate by microwave (MW) irradiation. The method offers highly convergent, inexpensive, and functionality-tolerable procedure for rapid access to important pyridazine compounds in good yields.

Hydrogen Production by Steam Reforming of Liquefied Natural Gas (LNG) Over Nickel-Phosphorus-Alumina Xerogel Catalyst Prepared by a Carbon-Templating Epoxide-Driven Sol-Gel Method.

Science.gov (United States)

Bang, Yongju; Park, Seungwon; Han, Seung Ju; Yoo, Jaekyeong; Choi, Jung Ho; Kang, Tae Hun; Lee, Jinwon; Song, In Kyu

2016-05-01

A nickel-phosphorus-alumina xerogel catalyst was prepared by a carbon-templating epoxide-driven sol-gel method (denoted as CNPA catalyst), and it was applied to the hydrogen production by steam reforming of liquefied natural gas (LNG). For comparison, a nickel-phosphorus-alumina xerogel catalyst was also prepared by a similar method in the absence of carbon template (denoted as NPA catalyst). The effect of carbon template addition on the physicochemical properties and catalytic activities of the catalysts in the steam reforming of LNG was investigated. Both CNPA and NPA catalysts showed excellent textural properties with well-developed mesoporous structure. However, CNPA catalyst retained a more reducible nickel aluminate phase than NPA catalyst. XRD analysis of the reduced CNPA and NPA catalysts revealed that nickel sintering on the CNPA catalyst was suppressed compared to that on the NPA catalyst. From H2-TPD and CH4-TPD measurements of the reduced CNPA and NPA catalysts, it was also revealed that CNPA catalyst with large amount of hydrogen uptake and strong hydrogen-binding sites showed larger amount of methane adsorption than NPA catalyst. In the hydrogen production by steam reforming of LNG, CNPA catalyst with large methane adsorption capacity showed a better catalytic activity than NPA catalyst.

Preparation and characterization of alumina supported nickel-oxalate catalyst for the hydrodeoxygenation of oleic acid into normal and iso-octadecane biofuel

International Nuclear Information System (INIS)

Ayodele, O.B.; Togunwa, Olayinka S.; Abbas, Hazzim F.; Daud, Wan Mohd Ashri Wan

2014-01-01

Highlights: • Preparation of nickel oxalate complex as catalyst precursor. • Incorporation of nickel oxalate complex into alumina support. • Characterization of the alumina supported nickel oxalate catalyst. • Hydrodeoxygenation of oleic acid with nickel oxalate catalyst. • Nickel oxalate catalyst reusability studies. - Abstract: In this study, nickel II oxalate complex (NiOx) was prepared by functionalization of nickel with oxalic acid (OxA) and incorporated into Al 2 O 3 to synthesize alumina supported nickel oxalate (NiOx/Al 2 O 3 ) catalyst for the hydrodeoxygenation (HDO) of oleic acid (OA) into biofuel. The synthesized NiOx/Al 2 O 3 was characterized and the X-ray fluorescence and elemental dispersive X-ray results showed that NiOx was successfully incorporated into the structure of Al 2 O 3 . The X-ray diffraction and Raman spectroscopy results confirmed that highly dispersed Ni species are present in the NiOx/Al 2 O 3 due to the functionalization with OxA. The catalytic activity of the NiOx/Al 2 O 3 on the HDO of OA produced a mixture of 21% iso-C18 and 72% n-C18 at a 360 °C, 20 bar, 30 mg NiOx/Al 2 O 3 loading pressure and gas flow rate of 100 mL/min. The presence of i-C 18 was ascribed to the OxA functionalization which increased the acidity of NiOx/Al 2 O 3 . The NiOx/Al 2 O 3 reusability study showed consistent HDO ability after 5 runs. These results are promising for further research into biofuel production for commercialization

Controlling the number of walls in multi walled carbon nanotubes/alumina hybrid compound via ball milling of precipitate catalyst

Energy Technology Data Exchange (ETDEWEB)

Nosbi, Norlin [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Akil, Hazizan Md, E-mail: hazizan@usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Cluster for Polymer Composite (CPC), Science and Engineering Research Centre, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia)

2015-06-15

Graphical abstract: - Highlights: • We report that, to manipulate carbon nanotubes geometry and number of walls are by controlling the precipitate catalyst size. • Number of walls and geometry effects depend on the milling time of the precipitate catalyst. • Increasing milling of time will decrease the carbon nanotubes number of walls. • Increasing milling of time will increase the carbon nanotubes thermal conductivity. - Abstract: This paper reports the influence of milling time on the structure and properties of the precipitate catalyst of multi walled carbon nanotubes (MWCNT)/alumina hybrid compound, produced through the chemical vapour deposition (CVD) process. For this purpose, light green precipitate consisted of aluminium, nickel(II) nitrate hexahydrate and sodium hydroxide mixture was placed in a planetary mill equipped with alumina vials using alumina balls at 300 rpm rotation speed for various milling time (5–15 h) prior to calcinations and CVD process. The compound was characterized using various techniques. Based on high-resolution transmission electron microscopy analysis, increasing the milling time up to 15 h decreased the diameter of MWCNT from 32.3 to 13.1 nm. It was noticed that the milling time had a significant effect on MWCNT wall thickness, whereby increasing the milling time from 0 to 15 h reduced the number of walls from 29 to 12. It was also interesting to note that the carbon content increased from 23.29 wt.% to 36.37 wt.% with increasing milling time.

Hydrogen production by steam reforming of liquefied natural gas (LNG) over nickel catalysts supported on cationic surfactant-templated mesoporous aluminas

Science.gov (United States)

Seo, Jeong Gil; Youn, Min Hye; Park, Sunyoung; Jung, Ji Chul; Kim, Pil; Chung, Jin Suk; Song, In Kyu

Two types of mesoporous γ-aluminas (denoted as A-A and A-S) are prepared by a hydrothermal method under different basic conditions using cationic surfactant (cetyltrimethylammonium bromide, CTAB) as a templating agent. A-A and A-S are synthesized in a medium of ammonia solution and sodium hydroxide solution, respectively. Ni/γ-Al 2O 3 catalysts (Ni/A-A and Ni/A-S) are then prepared by an impregnation method, and are applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of a mesoporous γ-Al 2O 3 support on the catalytic performance of Ni/γ-Al 2O 3 is investigated. The identity of basic solution strongly affects the physical properties of the A-A and A-S supports. The high surface-area of the mesoporous γ-aluminas and the strong metal-support interaction of supported catalysts greatly enhance the dispersion of nickel species on the catalyst surface. The well-developed mesopores of the Ni/A-A and Ni/A-S catalysts prohibit the polymerization of carbon species on the catalyst surface during the reaction. In the steam reforming of LNG, both Ni/A-A and Ni/A-S catalysts give better catalytic performance than the nickel catalyst supported on commercial γ-Al 2O 3 (Ni/A-C). In addition, the Ni/A-A catalyst is superior to the Ni/A-S catalyst. The relatively strong metal-support interaction of Ni/A-A catalyst effectively suppresses the sintering of metallic nickel and the carbon deposition in the steam reforming of LNG. The large pores of the Ni/A-A catalyst also play an important role in enhancing internal mass transfer during the reaction.

PENGARUH PERBEDAAN SIFAT PENYANGGA ALUMINA TERHADAP SIFAT KATALIS HYDROTREATING BERBASIS NIKEL-MOLIBDENUM

Directory of Open Access Journals (Sweden)

Maria Ulfah

2012-11-01

Full Text Available EFFECT OF ALUMINA SUPPORT PROPERTIES ON THE NICKEL-MOLIBDENUM BASE HYDROTREATING CATALYST. Effect of surface characteristics of three species of synthesized γ-alumina (alumina-1, alumina-2 and alumina-3 on characteristics NiMo catalysts has been studied. Those aluminas are derived from boehmite Catapal B by varying rasio mol nitric acid to boehmite. A sol-gel method is used to synthesize γ-Al2O3 support. The Nitrogen adsorption, X-ray diffraction (XRD, Temperature Programmed Reduction (TPR of H2, Temperature Programmed Desorption (TPD of NH3, and mechanical strength are used to characterize the supports and catalysts. The results showed that the surface area alumina affects the formation of crystalline MoO3 in the NiMo catalyst, while γ-Al2O3-3 support which has the highest surface area (about 195 m2/g compared to the other two types of alumina (>195 m2/g does not have a crystalline MoO3. The formation of crystalline MoO3 is not influenced by the acidity alumina. Based on the results of XRD, it is  indicated that the supported alumina-3 NiMo catalyst (having the highest acid strength shows that there is no presence of crystalline MoO3. Pore size distribution of support did not change significantly after the deposition of Ni and Mo oxides. Mechanical strength of support also affects the strength NiMo catalyst. Support alumina-3 which has the highest mechanical strength gives the mechanical strength of the highest NiMo catalyst. Pengaruh sifat penyangga γ-alumina hasil pengembangan (alumina-1, alumina-2 dan alumina-3 pada karakter katalis hydrotreating nikel-molibdenum (NiMo telah dipelajari. Ketiga jenis γ-alumina diturunkan dari boehmite “Catapal B” dengan menvariasikan nisbah mol asam nitrat terhadap boehmite. Pembuatan γ-alumina menggunakan metoda sol-gel. Adsorpsi Nitrogen, X-ray difraksi (XRD, Temperature Programmed Reduction (TPR H2, Temperature Programmed Desorption (TPD NH3, dan kekuatan mekanik digunakan untuk

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

.%. The catalysts were subsequently characterized by BET surface area, X-ray diffraction (XRD), Raman, UV–vis diffuse reflectance and X-ray absorption spectroscopy (XAS) as well as measurement of the catalytic performance. The catalysts had specific surface areas from 143 to 169 m2/g corresponding to average......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...... X-ray absorption near edge structure (XANES) spectroscopy showed that the vanadia can be reduced when operating at low oxygen concentrations. The catalyst performance was determined in fixed bed reactors with an inlet gas composition of C3H8/O2/N2=5/25/70. The main products were propene, CO and CO2...

The effect of Ni-Al ratio on the properties of coprecipitated nickel-alumina catalysts with high nickel contents

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Bosch, H.; van Ommen, J.G.; Ross, J.R.H.

1986-01-01

A series of nickel-alumina catalysts with a Ni/Al ratio between 3 and 20 has been prepared by coprecipitation. The calcination and reduction of these samples have been studied by thermogravimetry and their structures after calcination and reduction at different temperatures has been examined by

Propylene oxidation on catalytic Pt-Cu/y alumina. (Part II) chemical Kinetics of catalysts of Pt-Cu/y-alumina in the propylene oxidation

International Nuclear Information System (INIS)

Carballo, Luis M; Zea, Hugo R

1999-01-01

In this work is treated the effect of the composition of catalysts of Pt-Cu/y - alumina on the specific superficial activity corresponding to the total oxidation of propylene. Although the catalyst activity of the Cu in the operation conditions went practically null the specific activity of the catalytic Pt-Cu it incremented with the increase of the contained proportion of Cu in the catalyst. The total global speed by gram of catalyst was also increased with the introduction of Cu, but only to medium and high concentrations of propylene. The specific superficial activity was bigger for the sinterizated catalyst, for a given composition of the bimetallic catalyst, compared with that of the fresh catalyst (non-sinterizated). To explain, the catalytic behavior of the propylene oxidation, on the catalysts here studied, it is postulated that the propylene molecule it absorb with less force on the faces than in the corners or borders of the crystals of the catalyst and that the connection of adsorption on a place of given Pt is affected by the atoms of neighboring Cu on the surface causing changes in the mobility of the absorbed species. The kinetic results reveal a complex dependence between the reaction speed and the concentration of the propylene. In low concentrations of propylene the reaction speed was increased until to reach a maximum, and then to continue with a marked decreasing; and to concentrations. In bigger propylene concentrations, the reaction kinetics is presented as zero order with regard to the propylene, for some given concentrations of oxygen

Study on Pt-structured anodic alumina catalysts for catalytic combustion of toluene: Effects of competitive adsorbents and competitive impregnation methods

Science.gov (United States)

Zhang, Qi; Luan, Hongjuan; Li, Tao; Wu, Yongqiang; Ni, Yanhui

2016-01-01

Novel competitive impregnation methods were used to prepare high dispersion Pt-structured anodic alumina catalysts. It is found that competitive adsorbents owning different acidity result in different Pt loading amount and also exert great effects on Pt distribution, particle size and redox ability. The suitable adsorption ability of lactic acid led to its best activity for catalytic combustion of toluene. Co-competitive and pre-competitive impregnation methods were also compared and the mechanisms of two competitive methods were proposed. Co-competitive impregnation made Pt distribute more uniformly through pore channels and resulted in better catalytic activity, because of the weaker spatial constraint effect of lactic acid. Furthermore, the optimized Pt-structured anodic alumina catalyst also showed a good chlorine-resistance under moisture atmosphere, because water could promote the reaction of dichloromethane (DCM) transformation and clean chloride by-products to release more active sites.

Fischer-Tropsch Cobalt Catalyst Improvements with the Presence of TiO2, La2O3, and ZrO2 on an Alumina Support

Science.gov (United States)

Klettlinger, Jennifer Lindsey Suder

2012-01-01

The objective of this study was to evaluate the effect of titanium oxide, lanthanum oxide, and zirconium oxide on alumina supported cobalt catalysts. The hypothesis was that the presence of lanthanum oxide, titanium oxide, and zirconium oxide would reduce the interaction between cobalt and the alumina support. This was of interest because an optimized weakened interaction could lead to the most advantageous cobalt dispersion, particle size, and reducibility. The presence of these oxides on the support were investigated using a wide range of characterization techniques such as SEM, nitrogen adsorption, x-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed reduction after reduction (TPR-AR), and hydrogen chemisorptions/pulse reoxidation. Results indicated that both La2O3 and TiO2 doped supports facilitated the reduction of cobalt oxide species in reference to pure alumina supported cobalt catalysts, however further investigation is needed to determine the effect of ZrO2 on the reduction profile. Results showed an increased corrected cluster size for all three doped supported catalysts in comparison to their reference catalysts. The increase in reduction and an increase in the cluster size led to the conclusion that the support-metal interaction weakened by the addition of TiO2 and La2O3. It is also likely that the interaction decreased upon presence of ZrO2 on the alumina, but further research is necessary. Preliminary results have indicated that the alumina-supported catalysts with titanium oxide and lanthanum oxide present are of interest because of the weakened cobalt support interaction. These catalysts showed an increased extent of reduction, therefore more metallic cobalt is present on the support. However, whether or not there is more cobalt available to participate in the Fischer-Tropsch synthesis reaction (cobalt surface atoms) depends also on the cluster size. On one hand, increasing cluster size alone tends to decrease the

Synthesis and characterization of alumina-supported vanadium oxide catalysts prepared by the molecular designed dispersion of VO(acac)2 complexes

NARCIS (Netherlands)

Weckhuysen, B.M.; Baltes, M.; Voort, P. van der; Ramachandra Rao, R.; Catana, Gabriela; Schoonheydt, R.A.; Vansant, E.F.

2000-01-01

Alumina-supported vanadium oxide catalysts have been prepared by the molecular designed dispersion method, using the vanadyl acetylacetonate complex (VO(acac)2). The complex has been adsorbed on the support from solution, followed by thermal conversion into the corresponding supported vanadium oxide

Hydrodenitrogenation of heavy oil--1. Survey of hydrodenitrogenation catalysts

Energy Technology Data Exchange (ETDEWEB)

Nakamura, M.; Ono, T.; Togari, O.

1979-11-01

Forty catalysts consisting of binary oxides of silica/alumina, zirconium dioxide, titanium dioxide, or magnesium oxide or alumina/boron oxide, titanium dioxide, zirconium dioxide, or phosphorus pentoxide in various proportions, or of alumina alone, were screened for their activity for hydrodenitrogenation (kn) and hydrodesulfurization (ks) of a Gach Saran vacuum gas oil containing 0.16Vertical Bar3< nitrogen and 2.0Vertical Bar3< sulfur. The activities were correlated with the acid amount and acid strength of the catalysts as measured by temperature-programed desorption of ammonia. The mixed oxides of silica had low kn and low ks, and the kn was proportional to the acidity. The unmixed alumina catalysts showed low kn and high ks and no obvious relationship between activity and acidity. The binary alumina catalysts showed high kn and high ks and no obvious correlation between acidity and activity. Generally, catalysts with high acid strength had the lowest kn, especially the unmixed alumina.

Alumina- and titania-based monolithic catalysts for low temperature selective catalytic reduction of nitrogen oxides

International Nuclear Information System (INIS)

Blanco, J.; Avila, P.; Suarez, S.; Martin, J.A.; Knapp, C.

2000-01-01

The selective catalytic reduction of NO+NO 2 (NO x ) at low temperature (180-230C) with ammonia has been investigated with copper-nickel and vanadium oxides supported on titania and alumina monoliths. The influence of the operating temperature, as well as NH 3 /NO x and NO/NO 2 inlet ratios has been studied. High NO x conversions were obtained at operating conditions similar to those used in industrial scale units with all the catalysts. Reaction temperature, ammonia and nitrogen dioxide inlet concentration increased the N 2 O formation with the copper-nickel catalysts, while no increase was observed with the vanadium catalysts. The vanadium-titania catalyst exhibited the highest DeNO x activity, with no detectable ammonia slip and a low N 2 O formation when NH 3 /NO x inlet ratio was kept below 0.8. TPR results of this catalyst with NO/NH 3 /O 2 , NO 2 /NH 3 /O 2 and NO/NO 2 /NH 3 /O 2 feed mixtures indicated that the presence of NO 2 as the only nitrogen oxide increases the quantity of adsorbed species, which seem to be responsible for N 2 O formation. When NO was also present, N 2 O formation was not observed

Scalable synthesis of palladium nanoparticle catalysts by atomic layer deposition

International Nuclear Information System (INIS)

Liang Xinhua; Lyon, Lauren B.; Jiang Yingbing; Weimer, Alan W.

2012-01-01

Atomic layer deposition (ALD) was used to produce Pd/Al 2 O 3 catalysts using sequential exposures of Pd(II) hexafluoroacetylacetonate and formalin at 200 °C in a fluidized bed reactor. The ALD-prepared Pd/alumina catalysts were characterized by various methods including hydrogen chemisorption, XPS, and TEM, and compared with a commercially available 1 wt% Pd/alumina catalyst, which was also characterized. The content of Pd on alumina support and the size of Pd nanoparticles can be controlled by the number of ALD-coating cycles and the dose time of the Pd precursor. One layer of organic component from the Pd precursor remained on the Pd particle surface. The ALD 0.9 wt% Pd/alumina had greater active metal surface area and percent metal dispersion than the commercial 1 wt% Pd/alumina catalyst. The ALD and commercial catalysts were subjected to catalytic testing to determine their relative activities for glucose oxidation to gluconic acid in aqueous solution. The ALD 0.9 wt% Pd/alumina catalyst had comparable activity as compared to the commercial 1 wt% Pd catalyst. No noticeable amount of Pd leaching was observed for the ALD-prepared catalysts during the vigorously stirred reaction.

Advances in computational modeling of catalytic systems used in Claus sulfur recovery

Energy Technology Data Exchange (ETDEWEB)

Clark, P.D.; Lo, J. [Alberta Sulphur Research Ltd., Calgary, AB (Canada). Center for Applied Catalysis and Industrial Sulfur Chemistry

2010-01-15

This poster session discussed advances in computation modeling of catalytic systems used in Claus sulfur recovery, focusing on the hydrogen sulphide (H{sub 2}S) and sulphur dioxide (S{sub O}2) absorption of non-alumina Claus active metal oxides, such as titanium oxide and vanadium oxide. These metal oxides were chosen because they promote carbon disulphide (CS{sub 2}) conversion and have a potential use in olefin chemistry. The redox process of H{sub 2}S dissociation on vanadium pentoxide (V{sub 2}O{sub 2}) can take place in single-site reaction or multiple site reactions. Both mechanisms lead to the production of V{sub 2}O{sub 4}S, water (H{sub 2}O) and other species. The overall process of forming VO{sub 4}S is neutral, but kinetics is a controlling factor. The surface sulfidation to form V{sub 2}O{sub 3}S{sub 2} requires a small energy cost but possesses a huge reaction barrier. The formation of H{sub 2}S{sub 2} is energetically favorable. The silica (SiO{sub 2})-supported V{sub 2}O{sub 2} catalyst was described. A proposed mechanism of H{sub 2}S conversion to H{sub 2}O and V=S group was presented along with another reaction route in which the dissociative absorption of H{sub 2}S takes place on O-bridges instead of V=O. Two vanadia catalysts were compared: V{sub 2}O{sub 5} and V{sub 2}O{sub 5}/SiO{sub 2}. 7 figs.

Dibenzothiophene hydrodesulfurization over Ru promoted alumina based catalysts using in situ generated hydrogen

International Nuclear Information System (INIS)

Muhammad, Yaseen; Lu Yingzhou; Shen Chong; Li Chunxi

2011-01-01

Catalytic hydrodesulfurization (HDS) of dibenzothiophene (DBT) was carried out in a temperature range of 320-400 o C using in situ generated hydrogen coupled with the effect of selected organic additives for the first time. Four kinds of alumina based catalysts i.e. Co-Mo/Al 2 O 3 , Ni-Mo/Al 2 O 3 , Ru-Co-Mo/Al 2 O 3 and Ru-Ni-Mo/Al 2 O 3 were used for the desulfurization process, which were prepared following incipient impregnation method with fixed metal loadings (wt.%) of Co, Ni, Mo and Ru. The surface area, average pore diameter and pore volume distribution of the fresh and used catalysts were measured by N 2 adsorption using BET method. Catalytic activity was investigated in a batch autoclave reactor in the complete absence of external hydrogen gas. Addition and mutual reaction of specific quantities of water and ethanol provided the necessary in situ hydrogen for the desulfurization reaction. Organic additives like diethylene glycol (DEG), phenol, naphthalene, anthracene, o-xylene, tetralin, decalin and pyridine did impinge the HDS activity of the catalysts in different ways. Liquid samples from reaction products were quantitatively analyzed by HPLC technique while qualitative analyses were made using GC-MS. Both of these techniques showed that Ni-based catalysts were more active than Co-based ones at all conditions. Moreover, incorporation of Ru to both Co and Ni-based catalysts greatly promoted desulfurization activity of these catalysts. DBT conversion of up to 84% was achieved with Ru-Ni-Mo/Al 2 O 3 catalyst at 380 o C temperature for 11 h. Catalyst systems followed the HDS activity order as: Ru-Ni-Mo/Al 2 O 3 > Ni-Mo/Al 2 O 3 > Ru-Co-Mo/Al 2 O 3 > Co-Mo/Al 2 O 3 at all conditions. Cost effectiveness, mild operating conditions and reasonably high catalytic activity using in situ generated hydrogen mechanism proved our process to be useful for HDS of DBT.

Attrition resistant Fischer-Tropsch catalyst and support

Science.gov (United States)

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2004-05-25

A catalyst support having improved attrition resistance and a catalyst produced therefrom. The catalyst support is produced by a method comprising the step of treating calcined .gamma.-alumina having no catalytic material added thereto with an acidic aqueous solution having an acidity level effective for increasing the attrition resistance of the calcined .gamma.-alumina.

Synthesis, characterization and performance of NiMo catalysts supported on titania modified alumina for the hydroprocessing of different gas oils derived from Athabasca bitumen

Energy Technology Data Exchange (ETDEWEB)

Ferdous, D.; Bakhshi, N.N.; Dalai, A.K. [Catalysis and Chemical Reactor Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Sask. (Canada); Adjaye, J. [Syncrude Canada Ltd., Edmonton Research Center, No. 9421, 17th Avenue, Edmonton, Alta. (Canada)

2007-03-08

In this work, a series of NiMo/Al{sub 2}O{sub 3} catalyst was prepared using different Al{sub 2}O{sub 3} supports modified by titania (0-9 wt%). All modified supports and fresh catalysts were characterized by BET surface area, pore volume and pore diameter measurement, TPR, TPD, XRD, FTIR and Raman spectroscopy analyses. The initial activity of these catalysts were tested in a trickle-bed reactor using three different gas oils such as light gas oil (LGO), blended gas oil (blended: 50% LGO and 50% HGO) and heavy gas oil (HGO), all derived from Athabasca bitumen. Little structural change in alumina was observed with the incorporation of titania. XRD analysis showed the well dispersion of Ni and Mo on the support. Titania in alumina increased the formation of polymolybdenum oxide on the catalyst as evident from TPR and Raman analyses. Weak-intermediate-strong acid sites on the catalyst were observed at all titania concentrations. The Lewis and Bronsted acidity on the catalyst surface increased with the increase in titania concentration from 0 to 9 wt%. Nitrogen conversion increased from 57 to 71 wt%, from 83 to 93 wt% and from 75 to 80 wt% for LGO, blended and HGO, respectively and also sulfur conversion of LGO increased from 86 to 92 wt% when titania concentration was increased from 0 to 9 wt%. For blended and HGO, sulfur conversion was in the range 96-99 wt% at all titania concentrations. (author)

Dibenzothiophene hydrodesulfurization over Ru promoted alumina based catalysts using in situ generated hydrogen

Energy Technology Data Exchange (ETDEWEB)

Muhammad, Yaseen; Shen, Chong; Li, Chunxi [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Lu, Yingzhou [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

2011-02-15

Catalytic hydrodesulfurization (HDS) of dibenzothiophene (DBT) was carried out in a temperature range of 320-400 C using in situ generated hydrogen coupled with the effect of selected organic additives for the first time. Four kinds of alumina based catalysts i.e. Co-Mo/Al{sub 2}O{sub 3}, Ni-Mo/Al{sub 2}O{sub 3}, Ru-Co-Mo/Al{sub 2}O{sub 3} and Ru-Ni-Mo/Al{sub 2}O{sub 3} were used for the desulfurization process, which were prepared following incipient impregnation method with fixed metal loadings (wt.%) of Co, Ni, Mo and Ru. The surface area, average pore diameter and pore volume distribution of the fresh and used catalysts were measured by N{sub 2} adsorption using BET method. Catalytic activity was investigated in a batch autoclave reactor in the complete absence of external hydrogen gas. Addition and mutual reaction of specific quantities of water and ethanol provided the necessary in situ hydrogen for the desulfurization reaction. Organic additives like diethylene glycol (DEG), phenol, naphthalene, anthracene, o-xylene, tetralin, decalin and pyridine did impinge the HDS activity of the catalysts in different ways. Liquid samples from reaction products were quantitatively analyzed by HPLC technique while qualitative analyses were made using GC-MS. Both of these techniques showed that Ni-based catalysts were more active than Co-based ones at all conditions. Moreover, incorporation of Ru to both Co and Ni-based catalysts greatly promoted desulfurization activity of these catalysts. DBT conversion of up to 84% was achieved with Ru-Ni-Mo/Al{sub 2}O{sub 3} catalyst at 380 C temperature for 11 h. Catalyst systems followed the HDS activity order as: Ru-Ni-Mo/Al{sub 2}O{sub 3}> Ni-Mo/Al{sub 2}O{sub 3}> Ru-Co-Mo/Al{sub 2}O{sub 3}> Co-Mo/Al{sub 2}O{sub 3} at all conditions. Cost effectiveness, mild operating conditions and reasonably high catalytic activity using in situ generated hydrogen mechanism proved our process to be useful for HDS of DBT. (author)

Impeded solid state reactions and transformations in ceramic catalysts supports and catalysts

Directory of Open Access Journals (Sweden)

Ernő E. Kiss

2012-12-01

Full Text Available Impeded chemical reactions and impeded polymorphous transformation in materials are discussed, as desired effects, for stabilization of ceramic catalyst supports and ceramic based catalysts. This paper gives a short overview about the possibilities of slowing down the aging processes in ceramic catalyst supports and catalysts. Special attention is given to alumina and titania based catalysts.

Synthesis of Nano Crystalline Gamma Alumina from Waste Cans

Directory of Open Access Journals (Sweden)

Nada Sadoon Ahmedzeki

2018-03-01

Full Text Available In the present study waste aluminium cans were recycled and converted to produce alumina catalyst. These cans contain more than 98% aluminum oxide in their structure and were successfully synthesized to produce nano sized gamma alumina under mild conditions. A comprehensive study was carried out in order to examine the effect of several important parameters on maximum yield of alumina that can be produced. These parameters were reactants mole ratios (1.5, 1.5, 2, 3, 4 and 5, sodium hydroxide concentrations (10, 20, 30, 40, 50 and 55% and weights of aluminum cans (2, 4, 6, 8 and 10 g. The compositions of alumina solution were determined by Atomic absorption spectroscopy (AAS; and maximum yield of alumina solution was 96.3% obtained at 2 mole ratios of reactants, 40% sodium hydroxide concentrations and 10g of aluminum cans respectively. Gamma alumina was acquired by hydrothermal treatment of alumina solution at pH 7 and calcination temperature of 550 ºC. The prepared catalyst was characterized by X-ray diffraction (XRD, N2 adsorption/ desorption isotherms, X-ray fluorescence (XRF and atomic force microscopy (AFM. Results showed good crystallinity of alumina as described by XRD patterns, with surface area of 311.149 m2/g, 0.36 cm3/g pore volume, 5.248 nm pore size and particle size of 68.56 nm respectively.

Recycling of spent hydroprocessing catalysts: EURECAT technology

Energy Technology Data Exchange (ETDEWEB)

Berrebi, G.; Dufresne, P.; Jacquier, Y. (EURECAT-European Reprocessing Catalysts, La Voulte sur Rhone (France))

1994-04-01

Disposal of spent catalyst is a growing concern for all refiners. Environmental regulations are becoming stricter and stricter and there are State recommendations to develop disposal routes which would emphasize recycling as much as possible, and processing the wastes as near as possible to the production center. In this context, EURECAT has developed a recycling process for the hydroprocessing catalysts used in the oil refineries (NiMo, CoMo, NiW on alumina or mixed alumina silica). The process starts with a regeneration of the catalyst to eliminate hydrocarbons, carbon and sulfur. After a caustic roasting, the material is leached to obtain a solution containing mainly molybdenum (or tungsten) and vanadium, and a solid containing essentially alumina, cobalt and/or nickel. Molybdenum and vanadium are separated by an ion exchange resin technique. The solid is processed in an arc furnace to separate the alumina. Nickel and cobalt are separated by conventional solvent extraction to obtain pure metal. Alumina is disposed of as an inert slag. The strength of the process lies in the combination of proven technologies applied by companies whose reliability in their respective field is well known. The aspects concerning spent catalyst handling, packaging and transport are also discussed. 13 refs., 2 figs., 2 tabs.

Synergistic effect in the oxidation of benzyl alcohol using citrate-stabilized gold bimetallic nanoparticles supported on alumina

Energy Technology Data Exchange (ETDEWEB)

Gómez-Villarraga, Fernando, E-mail: ferchogomezv@gmail.com; Radnik, Jörg; Martin, Andreas; Köckritz, Angela [Leibniz-Institut für Katalyse e.V. an der Universität Rostock (Germany)

2016-06-15

Bimetallic nanoparticles (NPs) containing gold and various second metals (M = Pd, Pt, Cu, and Ag) supported on alumina (AuM/Alumina) were prepared using sodium citrate as stabilizer. In addition, supported monometallic Au/Alumina and Pd/Alumina were synthesized and tested to reveal synergistic effects in the catalytic evaluation of the bimetallic catalysts. The monometallic and bimetallic NPs revealed average sizes below 10 nm. The oxidation of benzyl alcohol with molecular oxygen as oxidant at mild conditions in liquid phase in the absence and presence (toluene or NaOH aqueous solution, 0.2 M) of a solvent was selected as test reaction to evaluate the catalytic properties of the above-mentioned solids. AuPd/Alumina exhibited the best catalytic activity among all bimetallic catalysts using toluene as solvent and under solvent-free conditions, respectively. In comparison to the monometallic catalysts, a synergistic effect with AuPd/Alumina was only evident in the solvent-free reaction. The AuPd/Alumina catalyst was able to oxidize benzyl alcohol selectively depending on the reaction medium into benzaldehyde (toluene or solvent-free) or benzoic acid (NaOH aqueous solution, 0.2 M). However, the catalyst deactivated due to particle growth of the bimetallic AuPd NPs by Ostwald ripening and leaching was not observed in the oxidation using toluene as solvent. The size of the catalytically active NPs, the metal composition of the particles, and the reaction conditions greatly influenced the catalytic oxidation results.Graphical Abstract.

Application of various types of alumina and nano--alumina sulfuric acid in the synthesis of α-aminonitriles derivatives: comparative study

Directory of Open Access Journals (Sweden)

A. Teimouri

2014-09-01

Full Text Available An efficient and green protocol for the synthesis of α-aminonitrile derivatives by one-pot reaction of different aldehydes with amines and trimethylsilyl cyanide has been developed using natural alumina, alumina sulfuric acid (ASA, nano-g-alumina, nano-g-alumina sulfuric acid (nano-g-ASA under microwave irradiation and solvent-free conditions. The advantages of methods are short reaction times, high yields, milder conditions and easy work up. The catalysts can be recovered for the subsequent reactions and reused without any appreciable loss of efficiency. DOI: http://dx.doi.org/10.4314/bcse.v28i3.13

Catalyst study for the plasma exhaust purification process

International Nuclear Information System (INIS)

Chabot, J.; Sannier, J.

1990-01-01

Several catalysts available from commercial sources have been screened to find out specific catalysts which allow complete methane oxidation and ammonia decomposition at temperature as low as possible in order to minimize tritium loss by permeation through processing equipment walls. Afterwards, an extended kinetic investigation has been performed on the best catalysts to achieve the data necessary to unit calculations. For methane oxidation, a palladium on alumina catalyst shows a very satisfactory low-temperature efficiency while a non-precious metal catalyst made of nickel oxide and alumina was found to be the more efficient for ammonia decomposition

Pt/Au nanoalloy supported on alumina and chlorided alumina: DFT and experimental analysis

Science.gov (United States)

Sharifi, N.; Falamaki, C.; Ghorbanzadeh Ahangari, M.

2018-04-01

Density functional theory (DFT) was used to explore the adsorption of Pt/Au nanoalloy onto a pure and chlorided γ-Al2O3(110) surface, which has been applied in numerous catalytic reactions. First, we considered the adsorption properties of Pt clusters (n ≤ 5) onto the Al2O3(110) surface to determine the most stable Pt cluster on alumina surface in reforming processes. After full structural relaxations of Pt clusters at various configurations on alumina, our computed results expressed that the minimum binding energy (‑5.67 eV) is accrued for Pt4 cluster and the distance between the nearest Pt atom in the cluster to the alumina surface is equal to 1.13 Å. Then, we investigated the binding energies, geometries, and electronic properties of adsorbed Aun clusters (n ≤ 6) on the γ-Al2O3(110) surface. Our studied showed that Au5 was the most thermodynamically stable structure on γ-Al2O3. Finally, we inspected these properties for adsorbed Au clusters onto the Pt4-decorated alumina (Aun/Pt4-alumina) system. The binding energy of the Au4/Pt4-alumina system was ‑5.01 eV, and the distance between Au4 cluster and Pt4-alumina was 1.33 Å. The Au4/Pt4alumina system was found to be the most stable nanometer-sized catalyst design. At last, our first-principles calculations predicted that the best position of embedment Cl on the Au4/Pt4-alumina.

Lump Kinetic Analysis of Syngas Composition Effect on Fischer-Tropsch Synthesis over Cobalt and Cobalt-Rhenium Alumina Supported Catalyst

Directory of Open Access Journals (Sweden)

Dewi Tristantini

2016-03-01

Received: 10th November 2015; Revised: 10th February 2016; Accepted: 16th February 2016 How to Cite: Tristantini, D., Suwignjo, R.K. (2016. Lump Kinetic Analysis of Syngas Composition Effect on Fischer-Tropsch Synthesis over Cobalt and Cobalt-Rhenium Alumina Supported Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 84-92. (doi:10.9767/bcrec.11.1.424.84-92 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.424.84-92

Storage of Nitrous Oxide (NOx in Diesel Engine Exhaust Gas using Alumina-Based Catalysts: Preparation, Characterization, and Testing

Directory of Open Access Journals (Sweden)

A. Alsobaai

2017-03-01

Full Text Available This work investigated the nitrous oxide (NOx storage process using alumina-based catalysts (K2 O/Al2 O3 , CaO/Al2 O3,  and BaO/Al2 O3 . The feed was a synthetic exhaust gas containing 1,000 ppm of nitrogen monoxide (NO, 1,000 ppm i-C4 H10 , and an 8% O2  and N2  balance. The catalyst was carried out at temperatures between 250–450°C and a contact time of 20 minutes. It was found that NOx was effectively adsorbed in the presence of oxygen. The NOx storage capacity of K2 O/Al2 O3 was higher than that of BaO/Al2 O3.  The NOx storage capacity for K2 O/Al2 O3  decreased with increasing temperature and achieved a maximum at 250°C. Potassium loading higher than 15% in the catalyst negatively affected the morphological properties. The combination of Ba and K loading in the catalyst led to an improvement in the catalytic activity compared to its single metal catalysts. As a conclusion, mixed metal oxide was a potential catalyst for de-NOx process in meeting the stringent diesel engine exhaust emissions regulations. The catalysts were characterized by a number of techniques and measurements, such as X-ray diffraction (XRD, electron affinity (EA, a scanning electron microscope (SEM, Brunner-Emmett-Teller (BET to measure surface area, and pore volume and pore size distribution assessments.

MoO3/Al2O3 catalyst: Comparison of catalysts prepared by new slurry impregnation with molybdic acid with conventional samples

International Nuclear Information System (INIS)

Spojakina, A.; Kostova, N.; Vit, Z.; Zdrazil, M.

2003-01-01

Alumina-supported molybdena catalysts were prepared by conventional impregnation with (NH 4 ) 6 Mo 7 O 24 (CIM) and by a new slurry impregnation method (SIM). SIM is the reaction of alumina support with a slurry of MoO 3 in water. Two commercial supports were used and the commercial Mo 3 /Al 2 O 3 catalyst was included for comparison. Maximum amount of MoO 3 deposited by SIM was about 19-20 % MoO 3 with the surface area of the support of 260-280 m 2 g -1 and this corresponded to saturation monolayer of similar density as described in literature for CIM catalysts. At the ratios of MoO 3 to Al 2 O 3 in the impregnation slurry below saturation monolayer, the pH of the slurry was 3.5-6 (depending on loading) and chemical erosion of alumina is negligible. However, using the large excess of MoO 3 (35% MoO 3 ) the pH was 2.4-3.4 and chemical erosion of alumina occurred. Silica contained in alumina supports was partly extracted as soluble silicomolybdic anions during SIM. The catalysts were characterized by BET, IR, DRS (UV-vis and NIR), TPR and catalytic activity in hydrodesulfurization of thiophene. Calcination had no significant effect on the properties of SIM catalysts and this proved that calcination is not needed in that method. All catalysts exhibited features of high monolayer dispersion of molybdena and no significant difference in structure and catalytic properties was observed between SIM and CIM catalysts. This confirmed that SIM is a simple, clean and reliable method of preparation of monolayer type MoO 3 /Al 2 O 3 catalysts. (author)

Hydroprocessing catalyst development

Energy Technology Data Exchange (ETDEWEB)

Boorman, P.M.; Kydd, R.A.; Sorensen, T.S.; Chong, K.; Lewis, J.

1992-08-01

Co-Mo and Ni-Mo hydroprocessing catalysts were examined for their activity in removal of sulfur from thiophene in model compounds, and in the cracking and hydrocracking of cumene. Three types of support materials were examined: carbon, modified carbon, and carbon covered alumina. The objective of the study was to examine the correlation between catalyst activity in the hydrodenitrogenation of model compounds, and the resistance of the catalyst to nitrogen poisoning during use in the hydroprocessing of gas oils. The use of model compound testing provided information on the individual catalytic reactions promoted by those materials. Infrared spectroscopy was used to study surface species on the catalysts and to explain many of the trends in activity observed, revealing the role of fluoride and phosphorus as a secondary promoter. Testing of the catalysts in hydrotreating of gas oils allowed comparison of model compound results with those from a real feedstock. The gas oil was also spiked with a model nitrogen compound and the results from catalytic hydrotreating of this material were compared with those from unspiked material. A key finding was that the carbon supported catalysts were the most effective in treating high-nitrogen feeds. The very favorable deactivation properties of carbon and carbon-covered alumina supported catalysts make these promising from an industrial point of view where catalyst deactivation is a limiting factor. 171 refs., 25 figs., 43 tabs.

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)

Rombi, E.; Gazzoli, D.; Cutrufello, M.G.; De Rossi, S.; Ferino, I.

2010-01-01

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.

New insides in the characterization of HDS industrial catalysts by HAADF-STEM

Science.gov (United States)

Del Angel, Paz; Ponce, Arturo; Arellano, Josefina; Yacaman, Miguel J.; Hernandez-Pichardo, Martha; Montoya, J. Ascencion; Escobar, Jose

2015-03-01

Hydrodesulfurization (HDS) catalysts are of great importance in the petroleum industry. Transition metal sulphides catalysts of Ni(Co)Mo(W)/Al2O3 are widely used for hydrotreating reactions, like hydrodenitrogenation and HDS. One of the main issue in these catalysts is to understand the mechanism of the reaction, where MoS2 plays the most important role in the catalytic activity. We studied an industrial NiMo/Alumina sulfide catalyst highly active by using aberration-corrected HAADF-STEM techniques. The used catalysts was a state-of- the art commercial nickel-molybdenum alumina-supported formulation, including organic agent modifier. This type of material belongs to a novel family of catalysts specially designed for ultra-low sulfur production from straight-run gas oil (SRGO), cycle oil, coker gas oil, or their combinations at operating conditions of commercial interest in hydrotreating units at industrial scale. Aberration corrected HAADF-STEM allowed to observe the nanostructure and location of MoS2 and his interaction with the alumina. The results indicate that the MoS2 is highly dispersed on the alumina, however the location of Ni is one of the task of this kind of catalyst.

Dehydration of alcohols over oxide catalysts: γ-eliminations -- stereospecificity and selectivity

International Nuclear Information System (INIS)

Siddhan, S.; Narayanan, K.

1979-01-01

The effect of alkali impregnation on alumina catalysts has been investigated by a physicochemical study of pure and modified alumina catalyst samples. The stereospecificity and selectivity of dehyration reactions, as well as the incidence of γ-elimination, have been studied by passing suitable substrates over catalyst samples. There was a change in the acidity-basicity balance in the sodium-impregnated alumina samples vis a vis pure alumina, while the surface area virtually remained constant. A higher propensity for γ-elimination was noticed with increases in basicity of the catalyst. 1-Olefin formation was found to be larger in more basic alumina- and thoria-catalyzed dehydration reactions. Thoria was strikingly unique in its capacity to dehydrate only alcohols, which have at least one β-hydrogen atom. Neopentyl alcohol could not be dehydrated even under drastic conditions. The modes of elimination in the case of alumina and thoria have been shown to be anti and syn, respectively, from the results of the dehydration studies with threo-3-methyl-2-pentanol. Studies of alcohols with proper β-substituents revealed that the cis preference is not universal in all catalytic eliminations but, in fact, depends on the mode of elimination. While cis-preference was noticed in alumina-catalyzed anti eliminations, trans-olefin was formed to a major amount in thoria-catalyzed syn-elimination processes. 9 figures, 13 tables

Adsorption and desorption of hydrogen and carbon monoxide were studied on alumina-supported iridium catalysts

Energy Technology Data Exchange (ETDEWEB)

Etherton, B.P.

1980-01-01

The adsorption and desorption of hydrogen and carbon monoxide were studied on alumina-supported iridium catalysts which were examined by a scanning transmission electron microscope (STEM). The metal particle size and number of particles per area of catalyst increased with increasing metal loading. The particles were approx. 10 A. in diameter, cubo-octahedral shaped, and approx. 80-90% disperse. The STEM electron beam caused negligible damage to the samples. Hydrogen adsorption measurements showed that the hydrogen-iridium atom ratio was 1.2:1-1.3:1 and increased with decreasing metal loading. Temperature-programed desorption showed four types of adsorbed hydrogen desorbing at -90/sup 0/C (I), 15/sup 0/C (IV), 115/sup 0/C (II), and 245/sup 0/C (III). Types II and IV desorb from single atom sites and Types I and III from multiple atom sites. Type I is in rapid equilibrium with the gas phase. All desorption processes appear to be first order. Carbon monoxide adsorbed nondissociatively at 25/sup 0/C with approx. 0.7:1 CO/Ir atom ratio. It adsorbed primarily in linear forms at low coverage, but a bridged form appeared at high coverage.

Cobalt oxide-molybdenum oxide-aluminum oxide catalyst : II. The structure of the catalyst

NARCIS (Netherlands)

Lipsch, J.M.J.G.; Schuit, G.C.A.

1969-01-01

The structure of the \\"Co molybdate on alumina\\" catalyst was investigated. Infrared spectra show that the Mo is present as MoO3. Reflection spectra lead to the conclusion that the Co is distributed throughout the bulk of the alumina as CoAl2O4, whereas the MoO3 is spread over the carrier surface,

Carbon a support for sulfide catalysts

NARCIS (Netherlands)

Vissers, J.P.R.; Lensing, T.J.; Mercx, F.P.M.; Beer, de V.H.J.; Prins, R.

1983-01-01

Two types of carbon materials, carbon black composite and carbon covered alumina, were studied for-their use as support for sulfide catalysts. The following parameters were varied: type of carbon black, carbon coverage of the alumina and carbon pretreatment. Pore size distributions were determined

Oxidative desulfurization of synthetic diesel using supported catalysts. Part 3. Support effect on vanadium-based catalysts

Energy Technology Data Exchange (ETDEWEB)

Cedeno-Caero, Luis; Gomez-Bernal, Hilda; Fraustro-Cuevas, Adriana; Guerra-Gomez, Hector D.; Cuevas-Garcia, Rogelio [UNICAT, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria 04510, Mexico D.F. (Mexico)

2008-04-15

Oxidesulfurization (ODS) of benzothiophenic compounds prevailing in diesel was conducted with hydrogen peroxide in presence of various catalysts, using a model diesel and actual diesel fuel. ODS activities of dibenzothiophenes (DBTs) in hexadecane for a series of V{sub 2}O{sub 5} catalysts supported on alumina, titania, ceria, niobia and silica, were evaluated. Results show that the oxidation activity of DBTs depends on the support used. It was observed that the sulfone yield is not proportional to textural properties or V content. For all catalysts, ODS of benzothiophene (BT), dibenzothiophene (DBT), 4-methyl dibenzothiophene (4-MDBT) and 4,6-dimethyl dibenzothiophene (4,6-DMDBT) decreased in the following order: DBT > 4-MDBT > 4,6-DMDBT > BT. This trend does not depend on the catalyst used or the textural properties of the catalysts and supports. In presence of indole ODS activities diminish, except with catalysts supported on alumina-titania mixed oxide, whereas with V{sub 2}O{sub 5}/TiO{sub 2} catalyst the performance is the highest. ODS of Mexican diesel fuel was carried out in presence of this catalyst and S level was diminished in about 99%. (author)

Catalyst for hydrocarbon conversion

International Nuclear Information System (INIS)

Duhaut, P.; Miquel, J.

1975-01-01

A description is given for a catalyst and process for hydrocarbon conversions, e.g., reforming. The catalyst contains an alumina carrier, platinum, iridium, at least one metal selected from uranium, vanadium, and gallium, and optionally halogen in the form of metal halide of one of the aforesaid components. (U.S.)

Desorption of Furfural from Bimetallic Pt-Fe Oxides/Alumina Catalysts

OpenAIRE

Gloria Lourdes Dimas-Rivera; Javier Rivera de la Rosa; Carlos J. Lucio-Ortiz; José Antonio De los Reyes Heredia; Virgilio González González; Tomás Hernández

2014-01-01

In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA). The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM) imaging revealed the intimate connection betwe...

Ceramic wash-coat for catalyst support

Science.gov (United States)

Kulkarni, Anand A.; Subramanian, Ramesh; Sabol, Stephen M.

2012-08-14

A wash-coat (16) for use as a support for an active catalyst species (18) and a catalytic combustor component (10) incorporating such wash-coat. The wash-coat is a solid solution of alumina or alumina-based material (Al.sub.2O.sub.3-0-3 wt % La.sub.2O.sub.3) and a further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina. The further oxide may be silicon dioxide (2-30 wt % SiO.sub.2), zirconia silicate (2-30 wt % ZrSiO.sub.4), neodymium oxide (0-4 wt %), titania (Al.sub.2O.sub.3-3-40% TiO.sub.2) or alumina-based magnesium aluminate spinel (Al.sub.2O.sub.3-25 wt % MgO) in various embodiments. The active catalyst species may be palladium and a second metal in a concentration of 10-50% of the concentration of the palladium.

Influence of alumina binder content on catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone.

Directory of Open Access Journals (Sweden)

Xiangjin Kong

Full Text Available The influence of the amount of alumina binders on the catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone was investigated in a fixed-bed reactor. N2 sorption, X-ray diffraction, H2-chemisorption and temperature-programmed desorption of ammonia were used to characterize the catalysts. It can be observed that the Ni/HZSM-5 catalyst bound with 30 wt.% alumina binder exhibited the best catalytic performance. The high catalytic performance may be due to relatively good Ni metal dispersion, moderate mesoporosity, and proper acidity of the catalyst.

Influence of alumina binder content on catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone.

Science.gov (United States)

Kong, Xiangjin; Liu, Junhai

2014-01-01

The influence of the amount of alumina binders on the catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone was investigated in a fixed-bed reactor. N2 sorption, X-ray diffraction, H2-chemisorption and temperature-programmed desorption of ammonia were used to characterize the catalysts. It can be observed that the Ni/HZSM-5 catalyst bound with 30 wt.% alumina binder exhibited the best catalytic performance. The high catalytic performance may be due to relatively good Ni metal dispersion, moderate mesoporosity, and proper acidity of the catalyst.

Synthesis of α-Alumina (Corundum) and its Application

International Nuclear Information System (INIS)

Nay Thwe Kyi; Kyaw Myo Naing; Tin Tin Aye; Nyunt Wynn

2005-09-01

This paper described the preparation of aluminium isopropoxide from aluminium sheet at different heating times.Aluminium sheet is found to have a reaction with absolute isopropyl alcohol and mercury (II) chloride as a catalyst under nitrogen atmosphere. Aluminium isopropoxide was characterized by NMR, XRD and IR. Aluminium isopropoxide serves as a molecular precursor to derive pure alumina gel by hydrolysis under both homogeneous and heterogeneous conditions. Pyrolysis to this alumina gel transforms it into -aluminia (corundum) at 1200'C. The phase transformation during pyrolysis was characterized by XRD, SEM and TEM. The alumina (corundum) has porous crystalline nature with high surface aera, which may be used as efficient adsorbent packing material in coloumn chromatography for the seperation of vitamin A from the leaves. -alumina can be also used in catalysis

Catalytic ozonation of fenofibric acid over alumina-supported manganese oxide

Energy Technology Data Exchange (ETDEWEB)

Rosal, Roberto, E-mail: roberto.rosal@uah.es [Departamento de Quimica Analitica e Ingenieria Quimica, Universidad de Alcala, E-28771 Alcala de Henares (Spain); Gonzalo, Maria S.; Rodriguez, Antonio; Garcia-Calvo, Eloy [Departamento de Quimica Analitica e Ingenieria Quimica, Universidad de Alcala, E-28771 Alcala de Henares (Spain)

2010-11-15

The catalytic ozonation of fenofibric acid was studied using activated alumina and alumina-supported manganese oxide in a semicontinuous reactor. The rate constants at 20 deg. C for the non-catalytic reaction of fenofibric acid with ozone and hydroxyl radicals were 3.43 {+-} 0.20 M{sup -1} s{sup -1} and (6.55 {+-} 0.33) x 10{sup 9} M{sup -1} s{sup -1}, respectively. The kinetic constant for the catalytic reaction between fenofibric acid and hydroxyl radicals did not differ significantly from that of homogeneous ozonation, either using Al{sub 2}O{sub 3} or MnO{sub x}/Al{sub 2}O{sub 3}. The results showed a considerable increase in the generation of hydroxyl radicals due to the use of catalysts even in the case of catalytic runs performed using a real wastewater matrix. Both catalysts promoted the decomposition of ozone in homogeneous phase, but the higher production of hydroxyl radicals corresponded to the catalyst with more activity in terms of ozone decomposition. We did not find evidence of the catalysts having any effect on rate constants, which suggests that the reaction may not involve the adsorption of organics on catalyst surface.

Synthesis and Characterization of Cobalt Containing Nanoparticles on Alumina A Potential Catalyst for Gas to Liquid Fuels Production

Science.gov (United States)

Cowen, Jonathan; Hepp, Aloysius F.

2016-01-01

Fisher-Tröpsch synthesis (FTS) is a century-old gas-to-liquid (GTL) technology that commonly employs cobalt (Co, on an oxide support) or iron (supported or not) species catalysts. It has been well established that the activity of the Co catalyst depends directly upon the number of surface Co atoms. The addition of promoter (mainly noble) metals has been widely utilized to increase the fraction of Co that is available for surface catalysis. Direct synthesis of Co nanoparticles is a possible alternative approach; our preliminary synthesis and characterization efforts are described. Materials were characterized by various transmission microscopies and energy dispersive spectroscopy. Tri-n-octylphosphine oxide (TOPO) and dicobalt octacarbonyl were heated under argon to a temperature of 180 deg with constant stirring for 1 hr. Quenching the reaction in toluene produced Co-containing nanoparticles with a diameter of 5 to 10 nm. Alternatively, an alumina support (SBA-200 Al2O3) was added; the reaction was further stirred and the temperature was decreased to 140 deg to reduce the rate of further growth/ripening of the nucleated Co nanoparticles. A typical size of Co-containing NPs was also found to be in the range of 5 to 10 nm. This can be contrasted with a range of 50 to 200 nm for conventionally-produced Co-Al2O3 Fischer-Tröpsch catalysts. This method shows great potential for production of highly dispersed catalysts that are either supported or unsupported.

Effect of support on hydro-metathesis of propene: A comparative study of W(CH 3 ) 6 anchored to silica vs. silica-alumina

KAUST Repository

Tretiakov, Mykyta; Samantaray, Manoja; Saidi, Aya; Basset, Jean-Marie

2018-01-01

Hydro-metathesis of propene was carried out by using well-defined W(CH3)6 supported on silica and silica-alumina. It was observed that W(CH3)6 supported silica-alumina catalyst is much better (TON 4577) than the silica supported catalyst (TON 2104

Productions of palm oil bio diesel whit heterogeneous basic catalysts compared to conventional homogeneous catalysts

International Nuclear Information System (INIS)

Rios, Luis A; Franco C, Alexander; Zuleta S, Ernesto

2009-01-01

The conventional process to produce biodiesel involves the presence of homogeneous basic catalysts. However, these catalysts have disadvantages associated to the need of purification steps, which increase the cost of the final product and generate pollution problems caused by the effluents. This paper compares different homogeneous and heterogeneous catalysts for the biodiesel production from palm oil. For this, heterogeneous catalysts supported on alumina were prepared and characterized by nitrogen adsorption, scanning electron microscopy, energy dispersive X ray spectroscopy and X ray diffraction. Transesterification of palm oil with methanol was accomplished at 60 celsius degrade and one hour, varying methanol/oil ratio, the type of catalyst and its concentration. Yields of the reaction and purity of the so obtained biodiesel were evaluated. Comparing the catalysts performance, based on the amount, was found that sodium methoxide (CH 3 ONa) and potassium carbonate supported on alumina (K 2 CO 3 /Al 2 O 3 ) were the catalysts that give the higher purity of biodiesel (96.8 and 95.85% respectively). When was determined the active site quality, by dividing the performance by each mole of active sites, it was found that calcined Na 2 SO 4 /Al 2 O 3 has the most active sites.

Decomposition of methane over alumina supported Fe and Ni–Fe bimetallic catalyst: Effect of preparation procedure and calcination temperature

Directory of Open Access Journals (Sweden)

A.S. Al-Fatesh

2018-02-01

Full Text Available Catalytic decomposition of methane has been studied extensively as the production of hydrogen and formation of carbon nanotube is proven crucial from the scientific and technological point of view. In that context, variation of catalyst preparation procedure, calcination temperature and use of promoters could significantly alter the methane conversion, hydrogen yield and morphology of carbon nanotubes formed after the reaction. In this work, Ni promoted and unpromoted Fe/Al2O3 catalysts have been prepared by impregnation, sol–gel and co-precipitation method with calcination at two different temperatures. The catalysts were characterized by X-ray diffraction (XRD, N2 physisorption, temperature programmed reduction (TPR and thermogravimetric analysis (TGA techniques. The catalytic activity was tested for methane decomposition reaction. The catalytic activity was high when calcined at 500 °C temperature irrespective of the preparation method. However while calcined at high temperature the catalyst prepared by impregnation method showed a high activity. It is found from XRD and TPR characterization that disordered iron oxides supported on alumina play an important role for dissociative chemisorptions of methane generating molecular hydrogen. The transmission electron microscope technique results of the spent catalysts showed the formation of carbon nanotube which is having length of 32–34 nm. The Fe nanoparticles are present on the tip of the carbon nanotube and nanotube grows by contraction–elongation mechanism. Among three different methodologies impregnation method was more effective to generate adequate active sites in the catalyst surface. The Ni promotion enhances the reducibility of Fe/Al2O3 oxides showing a higher catalytic activity. The catalyst is stable up to six hours on stream as observed in the activity results.

Continuous hydrogenation of ethyl levulinate to γ-valerolactone and 2-methyl tetrahydrofuran over alumina doped Cu/SiO2 catalyst: the potential of commercialization

Science.gov (United States)

Zheng, Junlin; Zhu, Junhua; Xu, Xuan; Wang, Wanmin; Li, Jiwen; Zhao, Yan; Tang, Kangjian; Song, Qi; Qi, Xiaolan; Kong, Dejin; Tang, Yi

2016-01-01

Hydrogenation of levulinic acid (LA) and its esters to produce γ-valerolactone (GVL) and 2-methyl tetrahydrofuran (2-MTHF) is a key step for the utilization of cellulose derived LA. Aiming to develop a commercially feasible base metal catalyst for the production of GVL from LA, with satisfactory activity, selectivity, and stability, Al2O3 doped Cu/SiO2 and Cu/SiO2 catalysts were fabricated by co-precipitation routes in parallel. The diverse physio-chemical properties of these two catalysts were characterized by XRD, TEM, dissociative N2O chemisorptions, and Py-IR methods. The catalytic properties of these two catalysts were systematically assessed in the continuous hydrogenation of ethyl levulinate (EL) in a fixed-bed reactor. The effect of acidic property of the SiO2 substrate on the catalytic properties was investigated. To justify the potential of its commercialization, significant attention was paid on the initial activity, proper operation window, by-products control, selectivity, and stability of the catalyst. The effect of reaction conditions, such as temperature and pressure, on the performance of the catalyst was also thoroughly studied. The development of alumina doped Cu/SiO2 catalyst strengthened the value-chain from cellulose to industrially important chemicals via LA and GVL. PMID:27377401

Rare earth metals for automotive exhaust catalysts

International Nuclear Information System (INIS)

Shinjoh, Hirohumi

2006-01-01

The usage of rare earth metals for automotive exhaust catalysts is demonstrated in this paper. Rare earth metals have been widely used in automotive catalysts. In particular, three-way catalysts require the use of ceria compounds as oxygen storage materials, and lanthana as both a stabilizer of alumina and a promoter. The application for diesel catalysts is also illustrated. Effects of inclusion of rare earth metals in automotive catalysts are discussed

Reaction Mechanism for m- Xylene Oxidation in the Claus Process by Sulfur Dioxide

KAUST Repository

Sinha, Sourab

2015-09-24

In the Claus process, the presence of aromatic contaminants such benzene, toluene, and xylenes (BTX), in the H2S feed stream has a detrimental effect on catalytic reactors, where BTX form soot particles and clog and deactivate the catalysts. Among BTX, xylenes are proven to be most damaging contaminant for catalysts. BTX oxidation in the Claus furnace, before they enter catalyst beds, provides a solution to this problem. A reaction kinetics study on m-xylene oxidation by SO2, an oxidant present in Claus furnace, is presented. The density functional theory is used to study the formation of m-xylene radicals (3-methylbenzyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, and 3,5-dimethylphenyl) through H-abstraction and their oxidation by SO2. The mechanism begins with SO2 addition on the radicals through an O-atom rather than the S-atom with the release of 180.0-183.1 kJ/mol of reaction energies. This exothermic reaction involves energy barriers in the range 3.9-5.2 kJ/mol for several m-xylene radicals. Thereafter, O-S bond scission takes place to release SO, and the O-atom remaining on aromatics leads to CO formation. Among four m-xylene radicals, the resonantly stabilized 3-methylbenzyl exhibited the lowest SO2 addition and SO elimination rates. The reaction rate constants are provided to facilitate Claus process simulations to find conditions suitable for BTX oxidation. © 2015 American Chemical Society.

Reaction Mechanism for m- Xylene Oxidation in the Claus Process by Sulfur Dioxide

KAUST Repository

Sinha, Sourab; Raj, Abhijeet; Al Shoaibi, Ahmed S.; Chung, Suk-Ho

2015-01-01

In the Claus process, the presence of aromatic contaminants such benzene, toluene, and xylenes (BTX), in the H2S feed stream has a detrimental effect on catalytic reactors, where BTX form soot particles and clog and deactivate the catalysts. Among BTX, xylenes are proven to be most damaging contaminant for catalysts. BTX oxidation in the Claus furnace, before they enter catalyst beds, provides a solution to this problem. A reaction kinetics study on m-xylene oxidation by SO2, an oxidant present in Claus furnace, is presented. The density functional theory is used to study the formation of m-xylene radicals (3-methylbenzyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, and 3,5-dimethylphenyl) through H-abstraction and their oxidation by SO2. The mechanism begins with SO2 addition on the radicals through an O-atom rather than the S-atom with the release of 180.0-183.1 kJ/mol of reaction energies. This exothermic reaction involves energy barriers in the range 3.9-5.2 kJ/mol for several m-xylene radicals. Thereafter, O-S bond scission takes place to release SO, and the O-atom remaining on aromatics leads to CO formation. Among four m-xylene radicals, the resonantly stabilized 3-methylbenzyl exhibited the lowest SO2 addition and SO elimination rates. The reaction rate constants are provided to facilitate Claus process simulations to find conditions suitable for BTX oxidation. © 2015 American Chemical Society.

Transmission electron microscopy on live catalysts

NARCIS (Netherlands)

Bremmer, G.M.

2017-01-01

The dissertation describes TEM experiments on heterogeneous catalysts. Starting with characterization of (Ni/Co)MoS2 on Alumina and the effect of oxidation, and sequential resulfidation. After that, Co-based catalysts are used for high-resolution (S)TEM/EDX caracterization studies, and in situ

11C-radioisotope study of methanol co-reaction with ethanol over Ni-MCM-41 silica-alumina and Ni-alumina

International Nuclear Information System (INIS)

Sarkadi-Priboczki, E.; Kovacs, Z.; Tsoncheva, T.; Kumar, N.; Murzin, D.Yu.

2009-01-01

Complete text of publication follows. The Ni modifies the properties of acidic alumina and light acidic MCM-41 silica-alumina supports. The radioisotopic method is a suitable tool for distinction of the 11 Cradioisotopic methanol and its co-derivates from derivates of non-radioactive ethanol on these catalysts. Experimental. The Ni/A l 2O 3 (5 wt % Ni) is commercially available while H-MCMN-41 (Si/Al=20) and Ni-ion-exchanged MCM-41 silica-alumina (5 wt % Ni) were prepared and characterized in previous works. Before catalysis the Ni/Al 2 O 3 and Ni-MCM-41 were pre-reduced. The 11 C-methanol was formed by a radiochemical process from 11 C-carbon dioxide produced at cyclotron (T 1/2 = 20.4 min). The mixture of equivalent volume of radioactive methanol and non-radioactive ethanol was introduced into glass tube micro-flow reactor at ambient temperature. After adsorption, the valves were closed and the catalyst was heated up to the required temperatures. The desorption rate of the remaining 11 C-derivatives on catalysts were continuously followed by radiodetectors and the derivatives of methanol with ethanol were analyzed by Radio/FID-gas chromatography (FID is coupled on-line with a radiodetector). The ethanol and its derivates were identified by FID while the 11 C-methanol and its co-derivates (with ethanol) were detected by both of FID and radiodetector. Results The 11 C-dimethyl ether was the common product of the single 11 C-methanol transformation on H-MCM-41, Ni-MCM-41 and Ni- Al 2 O 3 at low temperature (200-280 degC) due to middle strong acid sites. At higher temperature (280-350 degC), the dimethyl ether and hydrocarbons were the dominant products on H-MCM-41 while dimethyl ether selectivity decreased on Ni-alumina and Ni-MCM-41 in favor of methane. The selectivities of methanol to formaldehyde and methane were the highest on Ni-MCM-41. During co-reaction of 11 C-methanol with non-radioactive ethanol, the 11 C-labeled coethers, namely 11 C-methyl ethyl ether

Rare behaviour of a catalyst pellet catalyst dynamics

NARCIS (Netherlands)

Westerterp, K.R.; Loonen, R.A.; Martens, A.

1986-01-01

Temperature overshoots and undershoots were found for a Pd on alumina catalyst pellet in its course towards a new steady state after a change in concentration of one of the reactants ethylene or hydrogen. When cooling the pellet, after heat-up by reaction, with pure hydrogen a sudden temperature

Synthetic production of fuels by the Fischer Tropsch reaction using iron catalysts

International Nuclear Information System (INIS)

Rodriguez Cepeda, Rodrigo; Pacheco Ochoa, Luis

2004-01-01

A series of iron catalysts were prepared on three different types of supports: alumina and two activated carbons from eucalyptus woods and tagua seeds. Potassium was used as promoter and palladium was deposited by the excess wetness impregnation method. The catalysts were characterized by N 2 adsorption at 77 K, XRD and TPR analysis and evaluated as Fischer-Tropsch catalysts. The carbon supported catalysts favour the production of liquid hydrocarbons and decrease the aqueous phase. Those supported with alumina form gases and aqueous phase as the main products. The α p parameters of the Schulz-Flory distribution show hydrocarbons between gasoline and diesel

An Efficient Protocol for the Synthesis of Quinoxaline Derivatives at Room Temperature Using Recyclable Alumina-Supported Heteropolyoxometalates

Directory of Open Access Journals (Sweden)

Diego M. Ruiz

2012-01-01

Full Text Available We report a suitable quinoxaline synthesis using molybdophosphovanadates supported on commercial alumina cylinders as catalysts. These catalysts were prepared by incipient wetness impregnation. The catalytic test was performed under different reaction conditions in order to know the performance of the synthesized catalysts. The method shows high yields of quinoxaline derivatives under heterogeneous conditions. Quinoxaline formation was obtained using benzyl, o-phenylenediamine, and toluene as reaction solvent at room temperature. The CuH2PMo11VO40 supported on alumina showed higher activity in the tested reaction. Finally, various quinoxalines were prepared under mild conditions and with excellent yields.

Hydrotreating and hydrocracking of Athabasca bitumen derived heavy gas oils using NiMo catalyst supported on titania modified alumina

Energy Technology Data Exchange (ETDEWEB)

Ferdous, D.; Bakhshi, N.N.; Dalai, A.K.; Adjaye, J. [Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Chemical Engineering, Catalysis and Chemical Reaction Engineering Laboratories]|[Syncrude Canada Ltd., Edmonton, AB (Canada)

2006-07-01

Different NiMo catalysts supported on titania modified Al{sub 2}O{sub 3} were synthesized and characterized in an effort to study the hydrodenitrigenation (HDN) and hydrodesulfurization (HDS) of different gas oils derived from Athabasca bitumen. The Al{sub x}O{sub 3} supports were modified by incorporating up to 9 wt per cent titanium (Ti). All modified supports as well as fresh and spent catalysts were characterized by BET surface area, pore volume and pore diameter, XRD, TPR, TPD and SEM. A trickle-bed reactor using 3 different gas oils from the Athabasca bitumen was used to test the initial activity of these catalysts. The 3 oils were light gas oil (LGO), heavy gas oil (HGO) and blended gas oil having 50 per cent LGO and 50 per cent HGO. The study showed that nitrogen conversion increased for all the gas oils when Ti was incorporated into the alumina. With an increase in Ti concentrations from 0 to 6 wt per cent, nitrogen conversion increased from 57-69.5 wt per cent, 75-80.2 wt per cent, 83-91.5 wt per cent and for LGO, HGO and blended, respectively. Nearly 86 wt per cent sulphur conversion was obtained for all Ti concentrations for LGO, while HGO and blended sulphur conversions were in the range of 96-97 wt per cent. Detailed hydrotreating and hydrocracking of HGO was then performed using the 6 wt per cent Ti modified catalyst because it achieved the maximum nitrogen conversion. This paper also presented the temperature, pressure and liquid hourly space velocity for this catalyst along with the maximum nitrogen and sulphur conversions. Results were compared with those of commercial catalysts. tabs., figs.

Characterization of alumina supported molybdenum catalysts

Energy Technology Data Exchange (ETDEWEB)

Pastura, N M; Carmo, L M.P.M.; Sachett, C M.M.; Lam, Y L [Instituto Militar de Engenharia, Rio de Janeiro (Brazil). Secao de Quimica

1983-10-01

In order to optimize a bifunctional catalyst (acid and hydrogenating) of Mo/Al/sub 2/O/sub 3/, oxygen adsorption at 195 K and ethanol dehydration at 480-520 K were carried out using a series of these catalysts. The increase of Mo content increased the quantity of adsorbed oxygen, thus indicating that the number of hydrogenating sites also increased. The specific activity of ethanol dehydration varied slightly, indicating that the number of acid sites remains almost constant. On the other hand, the selectivity in ethylene (versus ether) increased markedly. This may be attributed to the increase in acid force of the acid sites.

Characterization of alumina supported molybdenum catalysts

International Nuclear Information System (INIS)

Pastura, N.M.; Carmo, L.M.P.M.; Sachett, C.M.M.; Lam, Y.L.

1983-01-01

In order to optimize a bifunctional catalyst (acid and hydrogenating) of Mo/Al 2 O 3 , oxygen adsorption at 195 K and ethanol dehydration at 480-520 K were carried out using a series of these catalysts. The increase of Mo content increased the quantity of adsorbed oxygen, thus indicating that the number of hydrogenating sites also increased. The specific activity of ethanol dehydration varied slightly, indicating that the number of acid sites remains almost constant. On the other hand, the selectivity in ethylene (versus ether) increased markedly. This may be attributed to the increase in acid force of the acid sites. (C.L.B.) [pt

{gamma} alumina- and HY zeolite-supported molybdenum catalysts: characterisation of the oxidic and sulfided phases; Catalyseurs a base de molybdene supporte sur alumine {gamma} et zeolithe HY: caracterisation des phases oxydes et sulfures

Energy Technology Data Exchange (ETDEWEB)

Plazenet, G

2001-10-01

Oxidic precursors of hydro-treatment catalysts (Co)Mo/alumina or zeolite were characterised by Raman spectroscopy, NMR and EXAFS at the Mo and Co K-edges. The formation of an Anderson-type alumino-molybdate compound upon impregnation of the support with an ammonium hepta-molybdate solution was confirmed for alumina, and also observed for the HY zeolitic support, with consumption of the amorphous alumina of the zeolite. In absence of the latter, ammonium hepta-molybdate precipitates. The species are conserved upon drying; upon calcination, the alumino-molybdate evolves into a surface aluminium molybdate type phase, whereas the hepta-molybdate transforms into MoO{sub 3}. The species formed upon impregnation are located in the inter-granular porosity whereas MoO{sub 3} vapor-condensation leads to formation of dimers located inside the zeolitic structure. The study of the cobalt-promoted precursors showed that the evolution of the molybdenum is the same in the case of co-impregnation preparation. Impregnation with cobalt-molybdate prevents the formation of the alumino-molybdate anion and thus enables the preservation of the Mo-Co interaction but, whatever the precursor, the leveling effect of the calcination-re-hydration steps was demonstrated. An EXAFS study at different sulfur coverages of the MoS{sub 2} platelets in the alumina-supported sulfided catalysts showed the limitations of EXAFS for size determination of MoS{sub 2} crystallites, a parameter that can be reached by AWAXS, which also conveys information about sheet-stacking. The EXAFS study of sulfided (Co)Mo/HY systems revealed incomplete sulfidation of the samples and the very high dispersion of the active phase. The absence of an observable Mo-Co interaction whatever the preparation of the promoted catalysts is consistent with the absence of promoting effect in toluene hydrogenation. (author)

Evidence for H2/D2 isotope effects on Fischer-Tropsch synthesis over supported ruthenium catalysts

International Nuclear Information System (INIS)

Kellner, C.S.; Bell, A.T.

1981-01-01

The effects of using D 2 rather than H 2 during Fischer-Tropsch synthesis were investigated using alumina- and silica-supported Ru catalysts. For the alumina-supported catalysts, the rate of CD 4 formation was 1.4 to 1.6 times faster than the formation of CH 4 . A noticeable isotope effect was also observed for higher molecular weight products. The magnitude of the isotope effects observed using the silica-supported catalyst was much smaller than that found using the alumina-supported catalysts. The formation of olefins relative to paraffins was found to be higher when H 2 rather than D 2 was used, independent of the catalyst support. The observed isotope effects are explained in terms of a mechanism for CO hydrogenation and are shown to arise from a complex combination of the kinetic and equilibrium isotope effects associated with elementary processes occurring on the catalyst surface

Nano-Engineered Catalysts for Direct Methanol Fuel Cells

Science.gov (United States)

Myung, Nosang; Narayanan, Sekharipuram; Wiberg, Dean

2008-01-01

Nano-engineered catalysts, and a method of fabricating them, have been developed in a continuing effort to improve the performances of direct methanol fuel cells as candidate power sources to supplant primary and secondary batteries in a variety of portable electronic products. In order to realize the potential for high energy densities (as much as 1.5 W h/g) of direct methanol fuel cells, it will be necessary to optimize the chemical compositions and geometric configurations of catalyst layers and electrode structures. High performance can be achieved when catalyst particles and electrode structures have the necessary small feature sizes (typically of the order of nanometers), large surface areas, optimal metal compositions, high porosity, and hydrophobicity. The present method involves electrodeposition of one or more catalytic metal(s) or a catalytic-metal/polytetrafluoroethylene nanocomposite on an alumina nanotemplate. The alumina nanotemplate is then dissolved, leaving the desired metal or metal/polytetrafluoroethylene-composite catalyst layer. Unlike some prior methods of making fine metal catalysts, this method does not involve processing at elevated temperature; all processing can be done at room temperature. In addition, this method involves fewer steps and is more amenable to scaling up for mass production. Alumina nanotemplates are porous alumina membranes that have been fabricated, variously, by anodizing either pure aluminum or aluminum that has been deposited on silicon by electronbeam evaporation. The diameters of the pores (7 to 300 nm), areal densities of pores (as much as 7 x 10(exp 10)sq cm), and lengths of pores (up to about 100 nm) can be tailored by selection of fabrication conditions. In a given case, the catalytic metal, catalytic metal alloy, or catalytic metal/ polytetrafluoroethylene composite is electrodeposited in the pores of the alumina nanotemplate. The dimensions of the pores, together with the electrodeposition conditions

High quality bio-oil from catalytic flash pyrolysis of lignocellulosic biomass over alumina-supported sodium carbonate

KAUST Repository

Imran, Ali; Bramer, Eddy A.; Seshan, Kulathuiyer; Brem, Gerrit

2014-01-01

Performance of a novel alumina-supported sodium carbonate catalyst was studied to produce a valuable bio-oil from catalytic flash pyrolysis of lignocellulosic biomass. Post treatment of biomass pyrolysis vapor was investigated in a catalyst fixed

Coking- and sintering-resistant palladium catalysts achieved through atomic layer deposition.

Science.gov (United States)

Lu, Junling; Fu, Baosong; Kung, Mayfair C; Xiao, Guomin; Elam, Jeffrey W; Kung, Harold H; Stair, Peter C

2012-03-09

We showed that alumina (Al(2)O(3)) overcoating of supported metal nanoparticles (NPs) effectively reduced deactivation by coking and sintering in high-temperature applications of heterogeneous catalysts. We overcoated palladium NPs with 45 layers of alumina through an atomic layer deposition (ALD) process that alternated exposures of the catalysts to trimethylaluminum and water at 200°C. When these catalysts were used for 1 hour in oxidative dehydrogenation of ethane to ethylene at 650°C, they were found by thermogravimetric analysis to contain less than 6% of the coke formed on the uncoated catalysts. Scanning transmission electron microscopy showed no visible morphology changes after reaction at 675°C for 28 hours. The yield of ethylene was improved on all ALD Al(2)O(3) overcoated Pd catalysts.

Extrudate versus Powder Silica Alumina as Support for Re2O7 Catalyst in the Metathesis of Seed Oil-Derivatives – A Comparison

Directory of Open Access Journals (Sweden)

Bassie B. Marvey

2009-01-01

Full Text Available Self- and cross-metathesis of fatty acid methyl esters (FAMEs was investigated using a silica alumina supported Re2O7 catalyst. Although a 3 wt% Re2O7/SiO2-Al2O3/SnBu4 is already active for the metathesis of unsaturated FAMEs, the results have shown that particle size of silica alumina support has a profound influence on its activity and selectivity. Consequently, high substrate conversions coupled with improved product yields (for mono- and diesters and reaction rates were obtained upon using powder, as opposed to extrudate silica alumina as the support material. Diesters are platform compounds for the synthesis of polymers and fragrances. In this paper a comparative outline of the influence of particle size of silica alumina (extrudate versus powder on catalytic performance of a 3 wt% Re2O7/SiO2-Al2O3/SnBu4 for self- and cross-metathesis of FAMEs is made. Low surface area and diffusion constraints associated with extrudates were identified as some of the factors leading to low catalytic activity and selectivity.

Preparation of mesoporous alumina particles by spray pyrolysis and application to double bond migration of 2-butene.

Science.gov (United States)

Song, Ki Chang; Kim, Joo Hyun; Kim, Jin Han; Jung, Kyeong Youl; Park, Young-Kwon; Jeon, Jong-Ki

2011-07-01

The objective of the present study is to investigate the catalytic performance of mesoporous alumina that were prepared via spray pyrolysis for double bond migration from 2-butene to 1-butene. The mesoporous alumina particles were prepared via spray pyrolysis by changing the types of organic surfactants and Al precursors. The texture and acidic properties of mesoporous alumina were analyzed through N2 adsorption, SEM, ammonia-temperature programmed desorption, and FT-IR of adsorbed pyridine. The morphologies and texture properties of the mesoporous alumina were found to have been strongly influenced by the combination of the Al precursor and the structure-directing agents. The mesoporous alumina samples had two kinds of acidic sites: a Lewis acid site and a H-bonded weak acid site. 1-Butene was produced selectively through double bond migration of 2-butene over all of the mesoporous alumina catalysts. The catalyst prepared by using a chloride compound as an aluminium precursor and CTAC as a structure-directing agent showed the highest activity in the double bond migration of 2-butene, which was attributed to its large surface area and an overall high amount of acid sites.

Effect of support on hydro-metathesis of propene: A comparative study of W(CH 3 ) 6 anchored to silica vs. silica-alumina

KAUST Repository

Tretiakov, Mykyta

2018-03-27

Hydro-metathesis of propene was carried out by using well-defined W(CH3)6 supported on silica and silica-alumina. It was observed that W(CH3)6 supported silica-alumina catalyst is much better (TON 4577) than the silica supported catalyst (TON 2104). We demonstrated that the present catalysts are much better than the previously reported (tantalum hydride/KCC-1, TON 786) catalyst. For the first time, we observed the formation of n-decane from propene, which enables us to think of using cheaper raw materials and converting them to petroleum range alkanes using hydro-metathesis reaction.

Following the evolution of morphology, composition and crystallography of alumina based catalysts after laser ablation: Implications for analysis by LA-ICP-AES

Energy Technology Data Exchange (ETDEWEB)

Alloncle, G. [Universite de Lyon, Lyon1, Laboratoire des Sciences Analytiques, CNRS UMR 5180, bat CPE, 43, boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex (France); Direction Physique et Analyses, Institut Francais du Petrole (IFP)-Lyon, BP3, F-69360 Solaize (France); Gilon, N., E-mail: gilon@univ-lyon1.fr [Universite de Lyon, Lyon1, Laboratoire des Sciences Analytiques, CNRS UMR 5180, bat CPE, 43, boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex (France); Legens, C.; Lienemann, C.-P.; Rebours, B.; Sorbier, L. [Direction Physique et Analyses, Institut Francais du Petrole (IFP)-Lyon, BP3, F-69360 Solaize (France); Morin, S.; Revel, R. [Direction Catalyse et Separation, Institut Francais du Petrole (IFP)-Lyon, BP3, F-69360 Solaize (France)

2009-08-30

Fundamental understanding of aerosol formation during laser ablation is important for the development of LA-ICP analysis of complex samples. Using a Lina Spark Atomizer{sup TM}, the application of this technique to the field of heterogeneous catalysis gave an accuracy of 5-15% while extreme values of +100% could be obtained in some cases. To improve understanding of laser ablation processes, particles generated during ablation of alumina based catalysts were collected and analysed using different microscopy and surface analysis techniques. Morphological study by scanning electron microscopy showed that most of the particles leaving the ablation cell were nanoparticle aggregates generated from vapor condensation. An XRD study of these aerosols revealed that the condensation converge on the formation of a spinel structure with large coherence domains. Elemental composition of the aerosol was also followed and exhibited differences between a catalyst containing large Mo concentration or low Pt concentration.

TiO2 nanotubes supported NiW hydrodesulphurization catalysts: Characterization and activity

International Nuclear Information System (INIS)

Palcheva, R.; Dimitrov, L.; Tyuliev, G.; Spojakina, A.; Jiratova, K.

2013-01-01

Highlights: ► NiW catalysts supported on TiO 2 nanotubes, titania and alumina. ► The best results are obtained with NiW/TiO 2 nanotubes in hydrodesulfurization (HDS) of thiophene. ► Active phase is Ni-WO x S y . ► Electronic promotion of W by Ti. - Abstract: High surface area TiO 2 nanotubes (Ti-NT) synthesized by alkali hydrothermal method were used as a support for NiW hydrodesulphurization catalyst. Nickel salt of 12-tungstophosphoric acid – Ni 3/2 PW 12 O 40 was applied as oxide precursor of the active components. The catalyst was characterized by S BET , XRD, UV–vis DRS, Raman spectroscopy, XPS, TPR and HRTEM. The results obtained were compared with those for the NiW catalysts prepared over high surface area titania and alumina supports. A polytungstate phase evidenced by Raman spectroscopy was observed indicating the destruction of the initial heteropolyanion. The catalytic experiments revealed two times higher thiophene conversion on NiW catalyst supported on Ti-NT than those of catalysts supported on alumina and titania. Increased HDS activity of the NiW catalyst supported on Ti-NT could be related to a higher amount of W oxysulfide entities interacting with Ni sulfide particles as consequence of the electronic effects of the Ti-NT observed with XPS analysis.

Carbon nanotube forests growth using catalysts from atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Chen, Bingan; Zhang, Can; Esconjauregui, Santiago; Xie, Rongsi; Zhong, Guofang; Robertson, John [Department of Engineering, University of Cambridge, Cambridge CB3 0FA (United Kingdom); Bhardwaj, Sunil [Istituto Officina dei Materiali-CNR Laboratorio TASC, s.s. 14, km 163.4, I-34012 Trieste (Italy); Sincrotone Trieste S.C.p.A., s.s. 14, km 163.4, I-34149 Trieste (Italy); Cepek, Cinzia [Istituto Officina dei Materiali-CNR Laboratorio TASC, s.s. 14, km 163.4, I-34012 Trieste (Italy)

2014-04-14

We have grown carbon nanotubes using Fe and Ni catalyst films deposited by atomic layer deposition. Both metals lead to catalytically active nanoparticles for growing vertically aligned nanotube forests or carbon fibres, depending on the growth conditions and whether the substrate is alumina or silica. The resulting nanotubes have narrow diameter and wall number distributions that are as narrow as those grown from sputtered catalysts. The state of the catalyst is studied by in-situ and ex-situ X-ray photoemission spectroscopy. We demonstrate multi-directional nanotube growth on a porous alumina foam coated with Fe prepared by atomic layer deposition. This deposition technique can be useful for nanotube applications in microelectronics, filter technology, and energy storage.

Development of a Catalyst/Sorbent for Methane Reforming

Energy Technology Data Exchange (ETDEWEB)

B.H. Shans; T.D. Wheelock; Justinus Satrio; Karl Albrecht; Tanya Harris Janine Keeley; Ben Silva; Aaron Shell; Molly Lohry; Zachary Beversdorf

2008-12-31

This project led to the further development of a combined catalyst and sorbent for improving the process technology required for converting CH{sub 4} and/or CO into H{sub 2} while simultaneously separating the CO{sub 2} byproduct all in a single step. The new material is in the form of core-in-shell pellets such that each pellet consists of a CaO core surrounded by an alumina-based shell capable of supporting a Ni catalyst. The Ni is capable of catalyzing the reactions of steam with CH{sub 4} or CO to produce H{sub 2} and CO{sub 2}, whereas the CaO is capable of absorbing the CO{sub 2} as it is produced. The absorption of CO{sub 2} eliminates the reaction inhibiting effects of CO{sub 2} and provides a means for recovering the CO{sub 2} in a useful form. The present work showed that the lifecycle performance of the sorbent can be improved either by incorporating a specific amount of MgO in the material or by calcining CaO derived from limestone at 1100 C for an extended period. It also showed how to prepare a strong shell material with a large surface area required for supporting an active Ni catalyst. The method combines graded particles of {alpha}-alumina with noncrystalline alumina having a large specific surface area together with a strength promoting additive followed by controlled calcination. Two different additives produced good results: 3 {micro}m limestone and lanthanum nitrate which were converted to their respective oxides upon calcination. The oxides partially reacted with the alumina to form aluminates which probably accounted for the strength enhancing properties of the additives. The use of lanthanum made it possible to calcine the shell material at a lower temperature, which was less detrimental to the surface area, but still capable of producing a strong shell. Core-in-shell pellets made with the improved shell materials and impregnated with a Ni catalyst were used for steam reforming CH{sub 4} at different temperatures and pressures. Under all

Micelle-derived catalysts for extended Schulz-Flory

Energy Technology Data Exchange (ETDEWEB)

Abrevaya, H.

1986-01-01

The objective of this program is to develop a synthesis gas conversion catalyst with higher selectivity to liquid fuels, while maintaining catalytic activity and stability at least equivalent relative to state-of-the-art precipitated iron catalysts. During this quarter, the emphasis in the program has been the investigation of the hydrocarbon cutoff hypothesis with supported ruthenium catalysts. An alumina-supported catalyst with smaller than 20[Angstrom] ruthenium particles was tested under conditions of maximal water gas shift activity. During this test more than 90% of the water made in the Fischer-Tropsch synthesis reaction was converted to H[sub 2]. However, the extent of ruthenium metal agglomeration was not reduced. Accordingly, it was not possible to conclude whether hydrocarbon cutoff occurs with smaller than 20[Angstrom] ruthenium particles on [gamma]-alumina. A ruthenium catalyst prepared on Y-type zeolite had 20[Angstrom] or smaller ruthenium particles according to STEM examination and a 15[Angstrom] average ruthenium metal particle size according to EXAFS examination. The ruthenium metal particle size was stable during the test with this catalyst. The hydrocarbon product distribution was Anderson-Schulz-Flory with no cutoff up to a carbon number of 160. A well-dispersed titania-supported ruthenium catalyst is going to be evaluated during the next quarter in order to determine whether hydrocarbon cutoff occurs.

Influence of silica-alumina support ratio on H2 production and catalyst carbon deposition from the Ni-catalytic pyrolysis/reforming of waste tyres.

Science.gov (United States)

Zhang, Yeshui; Tao, Yongwen; Huang, Jun; Williams, Paul

2017-10-01

The influence of catalyst support alumina-silica in terms of different Al 2 O 3 to SiO 2 mole ratios containing 20 wt.% Ni on the production of hydrogen and catalyst coke formation from the pyrolysis-catalysis of waste tyres is reported. A two-stage reactor system was used with pyrolysis of the tyres followed by catalytic reaction. There was only a small difference in the total gas yield and hydrogen yield by changing the Al 2 O 3 to SiO 2 mole ratios in the Ni-Al 2 O 3 /SiO 2 catalyst. The 1:1 ratio of Al 2 O 3 :SiO 2 ratio produced the highest gas yield of 27.3 wt.% and a hydrogen production of 14.0 mmol g -1 tyre . Catalyst coke formation decreased from 19.0 to 13.0 wt.% as the Al 2 O 3 :SiO 2 ratio was changed from 1:1 to 2:1, with more than 95% of the coke being filamentous-type carbon, a large proportion of which was multi-walled carbon nanotubes. Further experiments introduced steam to the second-stage reactor to investigate hydrogen production for the pyrolysis-catalytic steam reforming of the waste tyres using the 1:1 Al 2 O 3 /SiO 2 nickel catalyst. The introduction of steam produced a marked increase in total gas yield from ~27 wt. % to ~58 wt.%; in addition, hydrogen production was increased to 34.5 mmol g -1 and there was a reduction in catalyst coke formation to 4.6 wt.%.

High quality bio-oil from catalytic flash pyrolysis of lignocellulosic biomass over alumina-supported sodium carbonate

NARCIS (Netherlands)

Ali Imran, A.; Bramer, Eduard A.; Seshan, Kulathuiyer; Brem, Gerrit

2014-01-01

Performance of a novel alumina-supported sodium carbonate catalyst was studied to produce a valuable bio-oil from catalytic flash pyrolysis of lignocellulosic biomass. Post treatment of biomass pyrolysis vapor was investigated in a catalyst fixed bed reactor at the downstream of the pyrolysis

Claus sulphur recovery potential approaches 99% while minimizing cost

Energy Technology Data Exchange (ETDEWEB)

Berlie, E M

1974-01-21

In a summary of a paper presented to the fourth joint engineering conference of the American Institute of Chemical Engineers and the Canadian Society for Chemical Engineering, the Claus process is discussed in a modern setting. Some problems faced in the operation of sulfur recovery plants include (1) strict pollution control regulations; (2) design and operation of existing plants; (3) knowledge of process fundamentals; (4) performance testing; (5) specification of feed gas; (6) catalyst life; (7) instrumentation and process control; and (8) quality of feed gas. Some of the factors which must be considered in order to achieve the ultimate capability of the Claus process are listed. There is strong evidence to support the contention that plant operators are reluctant to accept new fundamental knowledge of the Claus sulfur recovery process and are not taking advantage of its inherent potential to achieve the emission standards required, to minimize cost of tail gas cleanup systems and to minimize operating costs.

Dry reforming of methane in the presence of ruthenium-based catalysts

International Nuclear Information System (INIS)

Safariamin, M.; Tidahy, L.H.; Abi-Aad, E.; Siffert, St.; Aboukais, A.

2009-01-01

The catalytic activities of ruthenium-based catalysts (5 wt% Ru) supported on alumina, ceria and ceria/alumina with different proportions of ceria (nCe 10 Al, n = 1, 3, 5; n = atomic ratio) were studied for the methane reforming reaction with CO 2 (CH 4 / CO 2 = 1) in the temperature range of 400-800 C. Evaluation of coke deposited after the reaction showed carbon deposition on Ru catalysts supported on CeO 2 , 1Ce 10 Al and 3Ce 10 Al, but not on Ru/Al 2 O 3 and Ru/5Ce 10 Al. Moreover, the sample Ru/5Ce 10 Al exhibited a higher activity than the other catalysts. (authors)

Iron-57 and iridium-193 Moessbauer spectroscopic studies of supported iron-iridium catalysts

International Nuclear Information System (INIS)

Berry, F.J.; Jobson, S.

1988-01-01

57 Fe and 193 Ir Moessbauer spectroscopy shows that silica- and alumina-supported iron-iridium catalysts formed by calcination in air contain mixtures of small particle iron(III) oxide and iridium(IV) oxide. The iridium dioxide in both supported catalysts is reduced in hydrogen to metallic iridium. The α-Fe 2 O 3 in the silica supported materials is predominantly reduced in hydrogen to an iron-iridium alloy whilst in the alumina-supported catalyst the iron is stabilised by treatment in hydrogen as iron(II). Treatment of a hydrogen-reduced silica-supported iron catalyst in hydrogen and carbon monoxide is accompanied by the formation of iron carbides. Carbide formation is not observed when the iron-iridium catalysts are treated in similar atmospheres. The results from the bimetallic catalysts are discussed in terms of the hydrogenation of associatively adsorbed carbon monoxide and the selectivity of supported iron-iridium catalysts to methanol formation. (orig.)

Active carbon catalyst for heavy oil upgrading

Energy Technology Data Exchange (ETDEWEB)

Fukuyama, Hidetsugu; Terai, Satoshi [Technology Research Center, Toyo Engineering Corporation, 1818 Azafujimi, Togo, Mobara-shi, Chiba 297-00017 (Japan); Uchida, Masayuki [Business Planning and Exploring Department, Overseas Business Development and Marketing Division, Toyo Engineering Corporation, 2-8-1 Akanehama, Narashino-shi, Chiba 275-0024 (Japan); Cano, Jose L.; Ancheyta, Jorge [Maya Crude Treatment Project, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, Mexico D.F. 07730 (Mexico)

2004-11-24

The active carbon (AC) catalyst was studied by hydrocracking of Middle Eastern vacuum residue (VR) for heavy oil upgrading. It was observed that the active carbon has the affinity to heavy hydrocarbon compounds and adsorption selectivity to asphaltenes, and exhibits better ability to restrict the coke formation during the hydrocracking reaction of VR. The mesopore of active carbon was thought to play an important role for effective conversion of heavy hydrocarbon compounds into lighter fractions restricting carbon formation. The performance of the AC catalyst was examined by continuous hydrocracking by CSTR for the removal of such impurities as sulfur and heavy metals (nickel and vanadium), which are mostly concentrated in the asphaltenes. The AC catalyst was confirmed to be very effective for the removal of heavy metals from Middle Eastern VR, Maya/Istmo VR and Maya VR. The extruded AC catalysts were produced by industrial manufacturing method. The application test of the extruded AC catalyst for ebullating-bed reactor as one of the commercially applicable reactors was carried out at the ebullating-bed pilot plant for 500h. The ebullition of the extruded AC catalyst was successfully traced and confirmed by existing {gamma}-ray density meter. The extruded AC catalyst showed stable performance with less sediment formation at an equivalent conversion by conventional alumina catalyst at commercial ebullating-bed unit. The degradation of the AC catalyst at the aging test was observed to be less than that of the conventional alumina catalyst. Thus, the AC catalyst was confirmed to be effective and suitable for upgrading of heavy oil, especially such heavy oils as Maya, which contains much heavy metals.

Catalyst for disproportionation/double-bond isomerization of olefins

International Nuclear Information System (INIS)

Hughes, W.; Reusser, R.

1980-01-01

An activated calcined homogenous catalyst composition consists essentially of a support uranium and at least one of tungsten and rhenium, wherein said composition contains about 0.1 to 25 weight percent total uranium, tungsten, and rhenium, each calculated as the metal; and a weight ratio of uranium:at least one of tungsten and rhenium of about 2:1 to 1:1. The activated catalyst composition is prepared by steps which comprise forming a homogenous composite, calcining said homogenous composite in a molecular oxygen-containing atmosphere at elevated temperatures, and subsequently activating said calcined homogenous composite under reducing conditions at elevated temperatures. The catalyst composition according to claim 1 is one in which the total of uranium, tungsten, and rhenium is about 1 to 15 weight percent. The catalyst composition according to claim 2 is one in which the ratio of uranium to at least one of tungsten and rhenium is about 2:1 to 0.5:1. The catalyst composition according to claim 3 is one in which the support is alumina, silica, silica-alumina, zirconia, titania, thoria, aluminum phosphate, magnisium silicate, zinc aluminate, or mixture. The catalyst composition according to claim 4is one in which support is silica

Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

International Nuclear Information System (INIS)

Amende, Max; Kaftan, Andre; Bachmann, Philipp; Brehmer, Richard; Preuster, Patrick; Koch, Marcus

2016-01-01

Graphical abstract: - Highlights: • We examine the regeneration of Pt-based catalysts poisoned by LOHC degradation. • A microscopic mechanism of the removal of degradation products from Pt is proposed. • Results of our UHV studies on model catalysts are transferred to real catalysis. • Oxidative regeneration of Pt/alumina is possible under mild conditions (600 K). • The degree and temperature regime of regeneration depends on the catalyst morphology. - Abstract: The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al_2O_3 model catalysts, and near-ambient pressure (NAP) measurements on real core–shell Pt/Al_2O_3 catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al_2O_3 model catalyst and core–shell pellet were only

Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

Energy Technology Data Exchange (ETDEWEB)

Amende, Max, E-mail: max.amende@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Kaftan, Andre, E-mail: andre.kaftan@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Bachmann, Philipp, E-mail: philipp.bachmann@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Brehmer, Richard, E-mail: richard.brehmer@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Preuster, Patrick, E-mail: patrick.preuster@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Koch, Marcus, E-mail: marcus.koch@crt.cbi.uni-erlangen.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); and others

2016-01-01

Graphical abstract: - Highlights: • We examine the regeneration of Pt-based catalysts poisoned by LOHC degradation. • A microscopic mechanism of the removal of degradation products from Pt is proposed. • Results of our UHV studies on model catalysts are transferred to real catalysis. • Oxidative regeneration of Pt/alumina is possible under mild conditions (600 K). • The degree and temperature regime of regeneration depends on the catalyst morphology. - Abstract: The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al{sub 2}O{sub 3} model catalysts, and near-ambient pressure (NAP) measurements on real core–shell Pt/Al{sub 2}O{sub 3} catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al{sub 2}O{sub 3} model catalyst and

Catalytic Ethanol Dehydration to Ethylene over Nanocrystalline χ- and γ-Al2O3 Catalysts.

Science.gov (United States)

Janlamool, Jakrapan; Jongsomjit, Bunjerd

2017-01-01

The study is aimed to investigate the combination of nanocrystalline γ- and χ- alumina that displays the attractive chemical and physical properties for the catalytic dehydration of ethanol. The correlation between the acid density and ethanol conversion was observed. The high acid density apparently results in high catalytic activity, especially for the equally mixed γ- and χ- phase alumina (G50C50). In order to obtain a better understanding on how different catalysts would affect the ethylene yield, one of the most powerful techniques such as X-ray photoelectron spectroscopy (XPS) was performed. Hence, the different O 1s surface atoms can be identified and divided into three types including lattice oxygen (O, 530.7 eV), surface hydroxyl (OH, 532.1 eV) and lattice water (H 2 O, 532.9 eV). It was remarkably found that the large amount of O 1s surface atoms in lattice water can result in increased ethylene yield. In summary, the appearance of metastable χ-alumina structure exhibited better catalytic activity and ethylene yield than γ- alumina. Thus, the introduction of metastable χ- alumina structure into γ- alumina enhanced catalytic activity and ethylene yield. As the result, it was found that the G50C50 catalyst exhibits the ethylene yield (80%) at the lowest reaction temperature ca. 250°C among other catalysts.

Oxidation of Commercial Petronas Diesel with Tert-Butyl Hydroperoxide Over Poly molybdate Alumina Supported Catalyst Modified With Alkaline Earth Metals

International Nuclear Information System (INIS)

Wan Nazwanie Wan Abdullah; Rusmidah Ali; Wan Azlee Wan Abu Bakar

2016-01-01

Due to strict environmental legislation for ultra-low sulfur diesel fuels, increasing technical and operational challenges are imposed to conventional hydrodesulfurization (HDS) technology. Therefore, catalytic oxidative desulfurization (Cat-ODS) has been suggested to be an alternative method to replace a conventional method which is hydrodesulfurization. In this study, catalytic oxidation of commercial diesel was performed using an oil-soluble oxidant, tert-butyl hydroperoxide (TBHP), over poly molybdate supported on alumina MoO_3-PO_4/ Al_2O_3 catalyst. A commercial Petronas diesel with 440 ppm of total sulfur was employed to evaluate the elimination of sulfur compounds. Besides, the percentage of sulfur removal was measured by (GC-FPD). Alkaline earth metals, such as Calcium (Ca), Barium (Ba) and Strontium (Sr) were introduced on the surface of MoO_3-PO_4/ Al_2O_3. The results showed that the catalytic activity decreased in the order, Ca/ MoO_3-PO_4/ Al_2O_3>Sr/ MoO_3-PO_4/ Al_2O_3> Ba/ MoO_3-PO_4/ Al_2O_3. The Ca/ MoO_3-PO_4/ Al_2O_3 catalyst was characterized by XRD and FESEM. XRD results showed that the best catalyst was highly amorphous while FESEM micrograph illustrated an aggregation and agglomeration of various particle sizes. The catalytic activity of Ca/ MoO_3-PO_4/ Al_2O_3 catalyst with various Ca/ Mo ratios were also studied. When the Ca/ Mo ratio was 15:85, the sulfur removal was the highest (79 %) at 45 degree Celsius, 30 min and O/ S molar ratio 3.0 with solvent = dimethylformamide (DMF), diesel/ solvent ratio = 1.0. (author)

Conversion of Claus plants of Kirkuk-Iraq to produce hydrogen and sulfur

International Nuclear Information System (INIS)

Naman, S.A.; Veziroglu, A.

2009-01-01

'Full text': Hydrogen production from rich sub-quality natural gas (SQNG) is visible technically with assessment of cost, safety and environmental toxicology analysis of hydrogen sulfide, is summarized. There are two Claus plants in Kirkuk-Iraq, converting hydrogen sulfide to elemental sulfur capacity of 2200 ton/day. One of these plants is working with only 400 ton/day and it is an old Claus process. The other is a modified Claus sulfur recovery process with a capacity of 1800 ton/day. Both of these plants operate with low efficiency due to lack of maintenance and the present situation in Iraq. Therefore, the agricultural area around Kirkuk is very polluted by this gas. Two pilot plants have been constructed inside the modified Claus plant in Kirkuk The first one is based on the flow system tube furnace reactor containing mixed Titanium oxide/sulfide with a cold trap for sulfur separation and a bath of 30% dithanolamine to separate and recycle H 2 S from hydrogen. The second pilot plant consists of a thermal diffusion ceramic rod inside a silica column containing Zeolit 5A as a catalyst. This pilot plant also consists of a trap for continuous separation of sulfur and a system for separation of hydrogen from unreacted H 2 S to recycle. The efficiency of conversion of H 2 S to hydrogen and sulfur has been optimized as a function of catalyst type and mixture, temperature of furnace, flow rate of gas and reactor materials until the efficiency reaches more than 97%. The Kirkuk natural gas consists of a mixture of CO 2 10% and H 2 S 12%. We found that these pilot plants were suitable with Cadmium chalcogens catalysts to produce hydrogen, methane, ethane and sulphur, but with lower efficiency than H 2 S decomposition only. Our aim in the second pilot plant, which consists of a silica column, was to supply the heat by solar energy concentrator instead of electricity as our catalyst needs 450 o C. and the solar intensity is about 1000 w/m 2 during the summer. The idea of

Synthesis of Gamma-Alumina from Kankara Kaolin as Potential ...

African Journals Online (AJOL)

In compounded zeolite catalyst it serves as the active matrix which aids the conversion of the bulkiest molecules in the feed owing to its larger pore size than zeolite. Large specific surface area gamma-alumina (γ-Al2O3) was synthesized by hydrothermal method using Kankara kaolin as starting material. Thermal treatment ...

Investigation and development of heavy oil upgrading catalysts. 3

Energy Technology Data Exchange (ETDEWEB)

Lee, D.K.; Lee, I.C.; Yoon, W.L.; Lee, H.T.; Chung, H.; Hwang, Y.J.; Park, S.H. [Korea Inst. of Energy Research, Taejon (Korea, Republic of)

1995-12-01

This study aimed at the domestic development of HDS catalysts which are most fundamental and wide-used in the petroleum refinery. In this year, some experimental works were conducted for developing the effective utilization technology of the novel dispersed-catalysts in the hydro-desulfurization of heavy oils, and improving the reaction performance of alumina-supported Mo-based hydro-treating catalysts conventionally used in most of refineries. First, it was experimentally proved that the dispersed catalysts of Co-Mo could be employed for the hydro-desulfurization of a heavy atmospheric residual oil excluding the catalyst deactivation. The utilization of a carbon-expanded reactor in combination with this dispersed catalyst system exhibited an enhanced reaction performance and provided an efficient way for the separation and recovery of the dispersed catalytic component from oils. Second, the tungsten-incorporated WCoMo/{gamma}-Al{sub 2}O{sub 3} catalyst revealed the improved catalytic performance in the various hydro-treating reactions and in the initial deactivation rates for the high pressure hydro-treatment of a heavy oil as compared with the commercial CoMo/{gamma}-Al{sub 2}O{sub 3} catalyst. This new experimental finding for the promoting role of the monomeric WO{sub 3} species in CoMo/{gamma}-Al{sub 2}O{sub 3} catalyst may be generally applicable to the Mo-based alumina-sulfide phase, higher catalytic activity, and more extended service life. (author). 101 refs., 33 figs., 18 tabs.

Regeneration of Hydrotreating and FCC Catalysts

Energy Technology Data Exchange (ETDEWEB)

CM Wai; JG Frye; JL Fulton; LE Bowman; LJ Silva; MA Gerber

1999-09-30

-earth exchanged Y zeolite in a silica-alumina matrix. X-ray fluorescence analyses showed that the rare earths used in preparing the catalysts were a mixture of lanthanum and cerium. Antimony found in the spent catalyst was added during operation of the FCC unit as a way to suppress the adverse effects of deposited nickel. The fresh HDS samples consisted of sulfided nickel and molybdenum on an alumina support. The spent catalyst showed nearly 10% vanadium on the catalyst and a modest increase in nickel and sulfur on the catalyst as a result of operations. Hydrocracking catalysts were not available for this study.

Bulk oil clauses

International Nuclear Information System (INIS)

Gough, N.

1993-01-01

The Institute Bulk Oil Clauses produced by the London market and the American SP-13c Clauses are examined in detail in this article. The duration and perils covered are discussed, and exclusions, adjustment clause 15 of the Institute Bulk Oil Clauses, Institute War Clauses (Cargo), and Institute Strikes Clauses (Bulk Oil) are outlined. (UK)

Support acidity influence in NiMoS (Nickel and Molybdenum) catalyst for Marlim diesel; Influencia da acidez do suport de catalisadores NiMoS (Niquel e Molibidenio) no hidrotratamento de diesel Marlim

Energy Technology Data Exchange (ETDEWEB)

Ferraz, Sheila Guimaraes de Almeida; Zotin, Jose Luiz; Jesus, Anderson Gomes de; Santos, Bruno Martins; Medeiros, Marcus Vinicius Costa [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

2008-07-01

The specification of diesel points to the reduction of the sulfur content, of the final boiling point, of the density range and increase of the cetane number. These two last properties are directly related with the ability of the hydrotreating catalytic system in promoting the hydrogenation of aromatic structures and ring opening of the naphthenic compounds, which are both associated to low cetane number. In such way, more acidic catalysts, able to promote the cracking of naphthenic structures, should be evaluated for the diesel HDT. Three bifunctional NiMo catalysts with the same metal content, different acidity and similar active phase dispersion were prepared using alumina, silica-alumina and alumina-Y zeolite as supports. These catalysts were evaluated in a micro-reactor unit for diesel HDT aiming to correlate their activity with the support acidity. The alumina and alumina-zeolite supported catalysts presented better performance than the one supported on silica-alumina. NiMo/alumina-zeolite showed higher cetane and density improvement, associated with a slight decrease in the initial boiling point. (author)

Thermal stability and microstructure of catalytic alumina composite support with lanthanum species

Science.gov (United States)

Ozawa, Masakuni; Nishio, Yoshitoyo

2016-09-01

Lanthanum (La) modified γ-alumina composite was examined for application toward thermostable catalytic support at elevated temperature. La added alumina was prepared through an aqueous process using lanthanum (III) nitrate and then characterized by surface area measurement, X-ray powder diffraction (XRD), differential thermal analysis (DTA), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoemission spectroscopy (XPS) and surface desorption of CO2. It was found that the properties depended on the La content and heat treatment temperatures. The characterization of the surface, structural and chemical properties of La-Al2O3 showed the existence of a strong interaction between the La species and alumina via formation of new phase and modified surface in Al2O3 samples. LaAlO3 nanoparticle formed among alumina particles by the solid phase reaction of Al2O3 and La2O3. The increase of the surface basicity of La modified alumina was demonstrated using CO2 temperature programmed desorption experiments. The controlled surface interaction between La oxide and alumina provide the unique surface and structural properties of the resulting mixed oxides as catalysts and catalytic supports.

Optimisation of Ag loading and alumina characteristics to give sulphur-tolerant Ag/Al₂O₃ catalyst for H₂-assisted NH₃-SCR of NO_x

DEFF Research Database (Denmark)

Fogel, Sebastian; Doronkin, Dmitry E.; Gabrielsson, Pär

2012-01-01

A series of Ag/Al2O3 catalysts with different alumina precursors and different Ag loadings were tested for H2 assisted NH3-SCR of NO. The catalysts were characterised (BET, XRD, NH3-TPD, ICP-OES, TEM and UV–vis spectroscopy) and tested as fresh catalyst, during long-term cycling tests with SO2 pr....... A higher Ag loading will affect the state of Ag by increasing the ratio of Ag-clusters and particles to highly dispersed Ag ions. SO2-poisoned Ag-clusters and particles can be regenerated by the high temperature treatment in the deNOx feed, highly dispersed Ag ions cannot....

Porous Alumina Films with Width-Controllable Alumina Stripes

Directory of Open Access Journals (Sweden)

Huang Shi-Ming

2010-01-01

Full Text Available Abstract Porous alumina films had been fabricated by anodizing from aluminum films after an electropolishing procedure. Alumina stripes without pores can be distinguished on the surface of the porous alumina films. The width of the alumina stripes increases proportionally with the anodizing voltage. And the pores tend to be initiated close to the alumina stripes. These phenomena can be ascribed to the electric field distribution in the alumina barrier layer caused by the geometric structure of the aluminum surface.

Porous Alumina Films with Width-Controllable Alumina Stripes

Science.gov (United States)

2010-01-01

Porous alumina films had been fabricated by anodizing from aluminum films after an electropolishing procedure. Alumina stripes without pores can be distinguished on the surface of the porous alumina films. The width of the alumina stripes increases proportionally with the anodizing voltage. And the pores tend to be initiated close to the alumina stripes. These phenomena can be ascribed to the electric field distribution in the alumina barrier layer caused by the geometric structure of the aluminum surface. PMID:21170406

Effect of Calcination Temperatures and Mo Modification on Nanocrystalline (γ-χ-Al2O3 Catalysts for Catalytic Ethanol Dehydration

Directory of Open Access Journals (Sweden)

Tharmmanoon Inmanee

2017-01-01

Full Text Available The mixed gamma and chi crystalline phase alumina (M-Al catalysts prepared by the solvothermal method were investigated for catalytic ethanol dehydration. The effects of calcination temperatures and Mo modification were elucidated. The catalysts were characterized by X-ray diffraction (XRD, N2 physisorption, transmission electron microscopy (TEM, and NH3-temperature programmed desorption (NH3-TPD. The catalytic activity was tested for ethylene production by dehydration reaction of ethanol in gas phase at atmospheric pressure and temperature between 200°C and 400°C. It was found that the calcination temperatures and Mo modification have effects on acidity of the catalysts. The increase in calcination temperature resulted in decreased acidity, while the Mo modification on the mixed phase alumina catalyst yielded increased acidity, especially in medium to strong acids. In this study, the catalytic activity of ethanol dehydration to ethylene apparently depends on the medium to strong acid. The mixed phase alumina catalyst calcined at 600°C (M-Al-600 exhibits the complete ethanol conversion having ethylene yield of 98.8% (at 350°C and the Mo-modified catalysts promoted dehydrogenation reaction to acetaldehyde. This can be attributed to the enhancement of medium to strong acid with metal sites of catalyst.

Catalyst study for the decontamination of atmospheres containing few traces of tritium

International Nuclear Information System (INIS)

Chabot, J.; Montel, J.; Sannier, J.

1988-01-01

The conversion of tritium at very low activity level using catalytic oxidation followed by water trapping is studied in the loop BEATRICE in order to measure kinetic parameters required for the design of the NET tritium clean-up system. Two precious-metal catalysts (Pd/alumina and Pt/alumina) are very efficient in removing tritium from contaminated gas mixtures down to a few MPC level at low temperatures, without need of isotopic swamping. However at room temperature, the trapping of tritium species on the catalyst surface gives rise to a progressive deactivation with time. Best regeneration conditions have to be determined in order to demonstrate industrial feasibility of operating at low temperatures

Peptide bond formation of alanine on silica and alumina surfaces as a catalyst

Science.gov (United States)

Sánchez Arenillas, M.; Mateo-Martí, E.

2012-09-01

Polymerization of amino acids has been important for the origin of life because the peptides may have been the first self-replicating systems. The amino acid concentrations in the oceans may have been too diluted in the early phases of the Earth. The formation of the biopolymers could have been due to the catalytic action of various minerals (such as silica or alumina). Our work is based on the comparison between alumina and silica minerals with and without prior activation of their silanol groups for the formation of peptide bonds using alanina like amino acid which it is the simplest quiral amino acid.

Ultrafiltro de alumina Alumina ultrafilter

Directory of Open Access Journals (Sweden)

M. F. de Souza

1999-06-01

Full Text Available Membranas de alumina AKP-50 foram preparadas sobre um substrato de alumina APC-SG de alta resistência mecânica. As membranas foram sinterizadas a 1000 °C e possuem uma distribuição estreita de poros de 40 a 90 nm, espessura média de 57 mm e taxa de fluxo de 0,4 m3/m2h. O filtro assim obtido é classificado como ultrafiltro sendo capaz de reter bactérias e alguns vírus. São quimicamente inertes e resistem a temperaturas inferiores a 1000 °C. A aderência entre as camadas permite a limpeza por contra-fluxo.Alumina ceramic membranes with unimodal pore size distribution in the 40 to 90 nm range were prepared on alumina porous substrates. The 57mm thickness membrane made from AKP-50 alumina shows 0,4 m3/m2h flow rate. The two layer substrate, prepared to have high mechanical strength, was made from commercially available APC-SG alumina. The filter made of three layers, membrane, intermediate layer and substrate, is classified as ultra-filter being able to retain bacteria and some viruses. Adherence between the three layers allows reverse washing. Filters are chemically inert and resistant to temperatures below 1000oC.

γ-Alumina Nanoparticle Catalyzed Efficient Synthesis of Highly Substituted Imidazoles

Directory of Open Access Journals (Sweden)

Bandapalli Palakshi Reddy

2015-10-01

Full Text Available γ-Alumina nano particle catalyzed multi component reaction of benzil, arylaldehyde and aryl amines afforded the highly substituted 1,2,4,5-tetraaryl imidazoles with good to excellent yield in less reaction time under the sonication as well as the conventional methods. Convenient operational simplicity, mild conditions and the reusability of catalyst were the other advantages of this developed protocol.

Solving non-linear Horn clauses using a linear Horn clause solver

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick; Ganty, Pierre

2016-01-01

In this paper we show that checking satisfiability of a set of non-linear Horn clauses (also called a non-linear Horn clause program) can be achieved using a solver for linear Horn clauses. We achieve this by interleaving a program transformation with a satisfiability checker for linear Horn...... clauses (also called a solver for linear Horn clauses). The program transformation is based on the notion of tree dimension, which we apply to a set of non-linear clauses, yielding a set whose derivation trees have bounded dimension. Such a set of clauses can be linearised. The main algorithm...... dimension. We constructed a prototype implementation of this approach and performed some experiments on a set of verification problems, which shows some promise....

Synthesis and characterization of Co and Ni catalysts supported on alumina, synthesized from aluminum industry wastes and its use in the reforming reaction of ethanol, to hydrogen production

International Nuclear Information System (INIS)

Saborio Gonzalez, Maricruz

2013-01-01

Alumina was synthesized from aluminum anodizing process wastes through a process of mechanical and thermal treatment of calcination,1373 K with a heating rate of 5 K/min to 8h, obtaining a pure alumina of corundum type, a crystal size of 9.77 nm. This material is used as a microporous support and have elaborated Cobalt heterogeneous catalysts (CO 3 O 4 / Al 2 O 3 ) and Nickel (NiO/Al 2 O 3 ) which were calcined at different temperatures (573 K, 773 K, 973 K, 1173 K). From these is produced hydrogen by ethenol catalytic reforming. Two techniques were used for driving the mixture EtOH:H 2 O (1:3) of starting gas. A first technique has involved trawling through boiling of the mixture. High percentages were obtained of hydrogen but to a lesser reaction time, consuming all starting reagent, the most efficient catalyst has been the CO 2 O 3 / Al 2 O 3 calcined at 973K with a production of H 2 of 50% v/v as well as CH 4 and CO of 10%v/v. The second type of starting reagent carryover has been mild heating at 333 K and nitrogen sweep, with the following results 11% v/v H 2 , 12% v/v CH 4 and 7% v/v CO. Addition of ethanol conversion maximums of 76% and hydrogen yield of 29%, of the theoretical yield based on the ethanol consumed. (author) [es

Acetic Acid Formation by Selective Aerobic Oxidation of Aqueous Ethanol over Heterogeneous Ruthenium Catalysts

DEFF Research Database (Denmark)

Gorbanev, Yury; Kegnæs, Søren; Hanning, Christopher William

2012-01-01

Heterogeneous catalyst systems comprising ruthenium hydroxide supported on different carrier materials, titania, alumina, ceria, and spinel (MgAl2O4), were applied in selective aerobic oxidation ethanol to form acetic acid, an important bulk chemical and food ingredient. The catalysts were...

Does main clause word order affect attention to change in subordinate clauses?

DEFF Research Database (Denmark)

Christensen, Marie Herget; Christensen, Tanya Karoli; Jensen, Torben Juel

2018-01-01

,and in the article we argue that this ‘Main Clause Phenomena’ (cf. Aelbrechtet al. 2012) functions as a foregroundingdevice, signaling that the more important information of the clause complex isto be found in the subordinate clause instead of in its matrix clause. Aprediction from the foregrounding hypothesis...... is that a subordinate clause withVerb>Adverb word order will attract more attention than a clause withAdverb>Verb word order. To test this, we conducted an experiment under the textchange paradigm. 59 students each read 24 constructions twice, each containinga subordinate clause with either Verb>Adverb or Adverb......>Verb word order.Half of the subordinate clauses were governed by a semifactive predicate (opento both word orders) and the other half by a semantically secondary sentence(in itself strongly favoring Verb>Adverb word order). Attention to thesubordinate clause was tested by measuring how disinclined...

Development of high performance catalyst for off-gas treatment system in BWR

International Nuclear Information System (INIS)

Kawasaki, Toru; Kawabe, Kenichi; Maeda, Kiyomitsu; Matsubara, Hirofumi; Aizawa, Motohiro; Iizuka, Hidehiro; Kumagai, Naoki

2011-01-01

A high performance catalyst for off-gas treatment system in boiling water reactor (BWR) has been developed. The hydrogen concentration in the outlets of off-gas recombiners increased at several BWR plants in Japan. These phenomena were caused by deactivation of catalysts for the recombiners, and we assumed two types of deactivation mechanisms. The first cause was an increase of the amount of boehmite in the catalyst support due to alternation of the manufacturing process. The other cause was catalysts being poisoned by cyclic siloxanes that were introduced from the silicone sealant used in the upstream of the off-gas recombiners. The catalysts were manufactured by Pt adhering on alumina support. The conventional catalyst (CAT-A) used the aqueous solution of the chloroplatinic acid for adhesion of Pt. A dechlorination process by autoclave was applied to prevent the equipment at the downstream of the recombiners from stress corrosion cracking, but this process caused the support material to transform into boehmite. The boehmite-rich catalysts were deactivated more easily by organic silicon than gamma alumina-rich catalysts. Therefore, the CAT-A was replaced at many Japanese BWR plants by the improved catalyst (CAT-B), and their support was transformed into more stable gamma alumina by heating at 500degC. However, the siloxanes keep being detected in the off-gas though the source of siloxane had been removed and there still remain possibilities to deactivate the catalysts. Therefore, we have been developing high performance catalyst (CAT-C) that has higher activity and durability against poisoning. We investigated the properties of CAT-C by performance tests and instrumental analyses. The dependency of thermal output of nuclear reactor, and durability against siloxane poisoning were investigated. We found that CAT-C showed higher performance and better properties than CAT-B did. Moreover, we have been developing a modeling method to evaluate the hydrogen recombination

Thermal stability and microstructure of catalytic alumina composite support with lanthanum species

Energy Technology Data Exchange (ETDEWEB)

Ozawa, Masakuni, E-mail: ozawa@numse.nagoya-u.ac.jp; Nishio, Yoshitoyo

2016-09-01

Highlights: • Thermal stability of La-modified γ-Al{sub 2}O{sub 3} with nanometer-scaled structure. • LaAlO{sub 3} particles are dispersed in the aggregated particles of alumina. • Increase of the surface basicity of La modified alumina using CO{sub 2}-TPD. - Abstract: Lanthanum (La) modified γ-alumina composite was examined for application toward thermostable catalytic support at elevated temperature. La added alumina was prepared through an aqueous process using lanthanum (III) nitrate and then characterized by surface area measurement, X-ray powder diffraction (XRD), differential thermal analysis (DTA), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoemission spectroscopy (XPS) and surface desorption of CO{sub 2}. It was found that the properties depended on the La content and heat treatment temperatures. The characterization of the surface, structural and chemical properties of La-Al{sub 2}O{sub 3} showed the existence of a strong interaction between the La species and alumina via formation of new phase and modified surface in Al{sub 2}O{sub 3} samples. LaAlO{sub 3} nanoparticle formed among alumina particles by the solid phase reaction of Al{sub 2}O{sub 3} and La{sub 2}O{sub 3}. The increase of the surface basicity of La modified alumina was demonstrated using CO{sub 2} temperature programmed desorption experiments. The controlled surface interaction between La oxide and alumina provide the unique surface and structural properties of the resulting mixed oxides as catalysts and catalytic supports.

Effects of temperature and feed composition on catalytic dehydration of methanol to dimethyl ether over {gamma}-alumina

Energy Technology Data Exchange (ETDEWEB)

Freshteh Raoof; Majid Taghizadeh; Ali Eliassi; Fereydoon Yaripour [Babol University of Technology, Babol (Iran). Chemical Engineering Department

2008-10-15

Catalytic dehydration of methanol to dimethyl ether (DME) is performed in an adiabatic fixed bed heterogeneous reactor by using acidic {gamma}-alumina. By changing the mean average temperature of the catalyst bed (or operating temperature of the reactor) from 233 up to 303{sup o}C, changes in methanol conversion were monitored. The results showed that the conversion of methanol strongly depended on the reactor operating temperature. Also, conversion of pure methanol and mixture of methanol and water versus time were studied and the effect of water on deactivation of the catalyst was investigated. The results revealed that when pure methanol was used as the process feed, the catalyst deactivation occurred very slowly. But, by adding water to the feed methanol, the deactivation of the {gamma}-alumina was increased very rapidly; so much that, by increasing water content to 20 weight percent by weight, the catalyst lost its activity by about 12.5-fold more than in the process with pure methanol. Finally, a temperature dependent model developed to predict pure methanol conversion to DME correlates reasonably well with experimental data. 11 refs., 9 figs., 3 tabs.

Coke formation on hydrodesulphurization catalysts. [Including effects of different promoters

Energy Technology Data Exchange (ETDEWEB)

Ternan, M.; Furimsky, E.; Parsons, B.I.

1979-02-01

The extent of coke formation was measured on a number of different hydrodesulfurization catalysts, primarily as a function of the catalyst chemical composition. Variations in the concentration of MoO/sub 3/ on the alumina, the type of catalyst promoter, the promoter/MoO/sub 3/ ratio, the presulfiding material and the reaction temperature were made. Increases in the reaction rate caused by either changes in the catalyst composition or by moderate changes in the reaction temperature were compared to the catalyst coke content. It was suggested that two types of coke were present on the catalyst, a reactive coke which is subsequently converted to reaction products and an unreactive coke which blocks catalytic sites.

Catalytic dehydration of ethanol using transition metal oxide catalysts.

Science.gov (United States)

Zaki, T

2005-04-15

The aim of this work is to study catalytic ethanol dehydration using different prepared catalysts, which include Fe(2)O(3), Mn(2)O(3), and calcined physical mixtures of both ferric and manganese oxides with alumina and/or silica gel. The physicochemical properties of these catalysts were investigated via X-ray powder diffraction (XRD), acidity measurement, and nitrogen adsorption-desorption at -196 degrees C. The catalytic activities of such catalysts were tested through conversion of ethanol at 200-500 degrees C using a catalytic flow system operated under atmospheric pressure. The results obtained indicated that the dehydration reaction on the catalyst relies on surface acidity, whereas the ethylene production selectivity depends on the catalyst chemical constituents.

Poisoning by carbon monoxide in the hydrogen exchange reaction between deuterium gas and water preadsorbed on a platinum--alumina catalyst

International Nuclear Information System (INIS)

Iida, I.; Tamaru, K.

1979-01-01

Poisoning by carbon monoxide in the exchange reaction between deuterium and the water preadsorbed on a platinum--alumina catalyst was studied, by measuring not only the rate of reaction but also its kinetic behavior and the adsorption of reactants on the catalyst surface. The shape of the poisoning curve is closely associated with the kinetic behavior and exhibited an abrupt change on freezing the adsorbed water below 273 0 K. When the rate is proportional to deuterium pressure and independent of the amount of water adsorbed, the exchange rate dropped sharply by carbon monoxide adsorbed of a few percent coverage without any marked changes in the amount and the rate of hydrogen adsorption on the platinum surface. However, at temperatures lower than 273 0 K and at higher deuterium pressures, the rate depends not on the deuterium pressure but on the amount of water adsorbed. The migration of hydrogen in or through the adsorbed water is seemingly sufficiently suppressed by freezing to control the overall reaction rate. In this case, a small amount of adsorption of carbon monoxide did not show any toxicity, but then a steep poisoning started accompanying a change in the kinetic behavior. It was accordingly demonstrated that the mechanism of the reaction may be better understood by studying poisoning and measuring adsorption, overall rate, and kinetic behavior

Synthesis and characterization of catalysts for the selective transformation of biomass-derived materials

Science.gov (United States)

Ghampson, Isaac Tyrone

The experimental work in this thesis focuses on generating catalysts for two intermediate processes related to the thermal conversion of lignocellulosic biomass: the synthesis and characterization of mesoporous silica supported cobalt catalysts for the Fischer-Tropsch reaction, and an exploration of the reactivity of bulk and supported molybdenum-based nitride catalysts for the hydrodeoxygenation (HDO) of guaiacol, a lignin model compound. The first section of the work details the synthesis of a series of silica-supported cobalt Fischer-Tropsch catalysts with pore diameters ranging from 2-23 nm. Detailed X-ray diffraction measurements were used to determine the composition and particle diameters of the metal fraction, analyzed as a three-phase system containing Cofcc, Cohcp and CoO particles. Catalyst properties were determined at three stages in catalyst history: (1) after the initial calcination step to thermally decompose the catalyst precursor into Co3O4, (2) after the hydrogen reduction step to activate the catalyst to Co and (3) after the FT reaction. From the study, it was observed that larger pore diameters supported higher turnover frequency; smaller pore diameters yielded larger mole fraction of CoO; XRD on post-reduction and post-FTS catalyst samples indicated significant changes in dispersivity after reduction. In the next section, the catalytic behaviors of unsupported, activated carbon-, alumina-, and SBA-15 mesoporous silica-supported molybdenum nitride catalysts were evaluated for the hydrodeoxygenation of guaiacol (2-methoxy phenol) at 300°C and 5 MPa. The nitride catalysts were prepared by thermal decomposition of bulk and supported ammonium heptamolybdate to form MoO 3 followed by nitridation in either flowing ammonia or a nitrogen/hydrogen mixture. The catalytic properties were strongly affected by the nitriding and purging treatment as well as the physical and chemical properties of support. The overall reaction was influenced by the

Biodiesel synthesis using K2CO3/Al–O–Si aerogel catalysts

Directory of Open Access Journals (Sweden)

IVANA LUKIĆ

2010-06-01

Full Text Available In this study, catalysts for fatty acid methyl esters (FAME or bio-diesel synthesis with K2CO3 as the active component on an alumina/silica support were synthesized using the sol–gel method, which was followed by drying the “dense” wet gels with supercritical carbon dioxide to obtain the aerogels. The prepared catalysts were characterized by XRD analysis, FTIR spectroscopy and N2 physisorption at 77 K, and tested in the methanolysis of sunflower oil. The effects of reaction variables, such as reaction time, temperature and methanol to oil molar ratio, on the yield of FAME were investigated. The aerogel catalysts with K2CO3 as the active component on an alumina/silica support exhibited good activity in the methanolysis of sunflower oil. The leaching of potassium when the catalyst was in contact with pure methanol under the working conditions of methanolysis was also tested in this study, indicating that it occurred only at higher temperatures, while at lower ones, it was negligible.

Rhenium Nanochemistry for Catalyst Preparation

Directory of Open Access Journals (Sweden)

Vadim G. Kessler

2012-08-01

Full Text Available The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of zeolites, ordered mesoporous MCM matrices, anodic mesoporous alumina, and porous transition metal oxides are considered. Structure-property relationships are traced for these catalysts in relation to such processes as alkylation and isomerization, olefin metathesis, selective oxidation of olefins, methanol to formaldehyde conversion, etc.

An Alumina-Supported Ni-La-Based Catalyst for Producing Synthetic Natural Gas

Directory of Open Access Journals (Sweden)

Daniel E. Rivero-Mendoza

2016-10-01

Full Text Available LaNi5, known for its hydrogen storage capability, was adapted to the form of a metal oxide-supported (γ-Al2O3 catalyst and its performance for the Sabatier reaction assessed. The 20 wt % La-Ni/γ-Al2O3 particles were prepared via solution combustion synthesis (SCS and exhibited good catalytic activity, achieving a CO2 conversion of 75% with a high CH4 selectivity (98% at 1 atm and 300 °C. Characteristics of the La-Ni/γ-Al2O3 catalyst were identified at various stages of the catalytic process (as-prepared, activated, and post-reaction and in-situ DRIFTS was used to probe the reaction mechanism. The as-prepared catalyst contained amorphous surface La–Ni spinels with particle sizes <6 nm. The reduction process altered the catalyst make-up where, despite the reducing conditions, Ni2+-based particles with diameters between 4 and 20 nm decorated with LaOx moieties were produced. However, the post-reaction catalyst had particle sizes of 4–9 nm and comprised metallic Ni, with the LaOx decoration reverting to a form akin to the as-prepared catalyst. DRIFTS analysis indicated that formates and adsorbed CO species were present on the catalyst surface during the reaction, implying the reaction proceeded via a H2-assisted and sequential CO2 dissociation to C and O. These were then rapidly hydrogenated into CH4 and H2O.

Catalysts, systems and methods to reduce NOX in an exhaust gas stream

Science.gov (United States)

Castellano, Christopher R.; Moini, Ahmad; Koermer, Gerald S.; Furbeck, Howard

2010-07-20

Catalysts, systems and methods are described to reduce NO.sub.x emissions of an internal combustion engine. In one embodiment, an emissions treatment system for an exhaust stream is provided having an SCR catalyst comprising silver tungstate on an alumina support. The emissions treatment system may be used for the treatment of exhaust streams from diesel engines and lean burn gasoline engines. An emissions treatment system may further comprise an injection device operative to dispense a hydrocarbon reducing agent upstream of the catalyst.

Application of zeolite-based catalyst to hydrocracking of coal-derived liquids

Energy Technology Data Exchange (ETDEWEB)

Shimada, H.; Sato, T.; Yoshimura, Y.; Hinata, A.; Yoshitomi, S.; Castillo Mares, A.; Nishijima, A. (National Chemical Laboratory for Industry, Tsukuba (Japan))

1990-06-01

Y-zeolite supported catalysts were applied to the hydrocracking of coal-derived liquids. By the introduction of two-stage upgrading consisting of hydrotreating and hydrocracking, Wandoan coal-derived middle distillate was hydrocracked over Ni-Mo/Y-zeolite, producing a high gasoline fraction yield. Zeolite supported catalysts gave little hydrocracked compounds in the hydroprocessing of coal-derived heavy oils, even after hydrotreatment. The reaction inhibitors which seriously poison the active sites of zeolites were found to be small nitrogen-containing molecules. In the hydroprocessing of coal-derived heavy oils, zeolite supported catalysts were inferior to alumina supported catalysts. This is due to the high hydrocracking but low hydrogenation activity of zeolite supported catalysts. 22 refs., 5 figs., 11 tabs.

An iron-57 Moessbauer spectroscopic study of titania-supported iron- and iron-iridium catalysts

International Nuclear Information System (INIS)

Berry, F.J.; Jobson, S.

1992-01-01

57 Fe Moessbauer spectroscopy shows that titania-supported iron is reduced by treatment in hydrogen at significantly lower temperatures than corresponding silica- and alumina-supported catalysts. The metallic iron formed under hydrogen at 600deg C is partially converted to carbide by treatment in carbon monoxide and hydrogen. In contrast to its alumina- and silica-supported counterparts, the remainder of the titania-supported iron is unchanged by this gaseous mixture. The 57 Fe Moessbauer spectra of EXAFS show that iron and iridium in the titania-supported iron-iridium catalysts are reduced in hydrogen at even lower temperatures and, after treatment at 600deg C, are predominantly present as the iron-iridium alloy. The treatment of these reduced catalysts in carbon monoxide and hydrogen is shown by Moessbauer spectroscopy and EXAFS to induce the segregation of iron from the iron-iridium alloy and its conversion to iron oxide. (orig.)

Reaction selectivity studies on nanolithographically-fabricated platinum model catalyst arrays

Energy Technology Data Exchange (ETDEWEB)

Grunes, Jeffrey Benjamin [Univ. of California, Berkeley, CA (United States)

2004-05-01

In an effort to understand the molecular ingredients of catalytic activity and selectivity toward the end of tuning a catalyst for 100% selectivity, advanced nanolithography techniques were developed and utilized to fabricate well-ordered two-dimensional model catalyst arrays of metal nanostructures on an oxide support for the investigation of reaction selectivity. In-situ and ex-situ surface science techniques were coupled with catalytic reaction data to characterize the molecular structure of the catalyst systems and gain insight into hydrocarbon conversion in heterogeneous catalysis. Through systematic variation of catalyst parameters (size, spacing, structure, and oxide support) and catalytic reaction conditions (hydrocarbon chain length, temperature, pressures, and gas composition), the data presented in this dissertation demonstrate the ability to direct a reaction by rationally adjusting, through precise control, the design of the catalyst system. Electron beam lithography (EBL) was employed to create platinum nanoparticles on an alumina (Al₂O₃) support. The Pt nanoparticle spacing (100-150-nm interparticle distance) was varied in these samples, and they were characterized using x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), both before and after reactions. The TEM studies showed the 28-nm Pt nanoparticles with 100 and 150-nm interparticle spacing on alumina to be polycrystalline in nature, with crystalline sizes of 3-5 nm. The nanoparticle crystallites increased significantly after heat treatment. The nanoparticles were still mostly polycrystalline in nature, with 2-3 domains. The 28-nm Pt nanoparticles deposited on alumina were removed by the AFM tip in contact mode with a normal force of approximately 30 nN. After heat treatment at 500 C in vacuum for 3 hours, the AFM tip, even at 4000 nN, could not remove the platinum

Hydrogenation of hexene over platinum on alumina vs. platinum in a Na-Y zeolite

International Nuclear Information System (INIS)

Miner, R.S. Jr.; Ione, K.G.; Namba, S.; Turkevich, J.

1978-01-01

In order to study the efficacy of zeolites as supports, several platinum H--Y zeolites were prepared by ion exchanging an H--Y zeolite with Pt(NH 3 ) 4 Cl 2 and reducing these products with hydrazine hydrate (A, B, C). Another preparation was made by adsorbing 32-A platinum sol on the zeolite crystallites (D). These catalysts were studied for hydrogenation and isomerization of hexene-1, ethylene hydrogenation, hydrogen chemisorption, and poison titration. They were compared with monodisperse Pt (32 A diameter) on alumina. A marked difference was found between the behavior of hexene-1 with the platinum-in-zeolite and with the platinum-on-alumina

MoO3/Al2O3 Catalyst: Comparison of Catalysts Prepared by New Slurry Impregnation with Molybdic Acid with Conventional Samples

Czech Academy of Sciences Publication Activity Database

Spojakina, A. A.; Kostova, N. G.; Vít, Zdeněk; Zdražil, Miroslav

2003-01-01

Roč. 77, - (2003), s. 767-778 ISSN 0137- 5083 R&D Projects: GA AV ČR IAA4072802 Institutional research plan: CEZ:AV0Z4072921 Keywords : hydrodesulfurization * molybdenum sulphide catalyst * alumina supported molybdenum oxide Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.515, year: 2003

zeolite catalysts for the selective synthesis of mono- and diethylamines

NARCIS (Netherlands)

Veefkind, V.A.; Lercher, J.A.

1998-01-01

The kinetics and mechanism of ethylamine synthesis from ammonia and ethanol over several large pore acid catalysts are described. Mordenite produced higher monoethylamine yields than the zeolites beta, Y, mazzite, and amorphous silica–alumina. The reaction proceeds via the initial formation of

Cobalt and KNO3 supported on alumina catalysts for diesel soot combustion

International Nuclear Information System (INIS)

Grzona, Claudia B.; Lick, Ileana D.; Castellon, Enrique Rodriguez; Ponzi, Marta I.; Ponzi, Esther N.

2010-01-01

The catalytic combustion of diesel soot was studied in the presence of fresh and aged catalysts: Co/Al 2 O 3 , KNO 3 /Al 2 O 3 and Co/KNO 3 /Al 2 O 3 . The catalysts were prepared by impregnation using nitrate solutions. The catalysts were characterized by X-ray diffraction, thermal programmed reduction, vibrational spectroscopy and X-ray photoelectron spectroscopy. Fresh and aged catalysts present high activity in presence of O 2 and O 2 /NO. The values of the combustion temperature decrease more than 200 deg. C with respect to that observed in the process without catalysis. The activity is associated with the presence of KNO 3 and the role of this salt can be attributed to the contribution of NO 3 - /NO 2 - redox cycle.

Production of olefins from bioethanol. Catalysts, mechanism

Directory of Open Access Journals (Sweden)

Kusman Dossumov

2012-12-01

Full Text Available This review describes methods of catalytic obtaining from bioethanol of valuable industrial products – olefins, particularly ethylene. Аmong olefins, ethylene is the most popular key raw material of petrochemical synthesis. The scope of appllication of ethylene is almost unlimited in petrochemical products: polyethylene, ethylbenzene, styrene, ethylene dichloride, vinyl chloride etc. It also examines catalysts for the production of olefins and their properties. The most promising and commercially advantageous process of ethylene production by catalytic dehydration of ethanol on catalysts based on modified alumina. And this review discusses the mechanisms of catalytic conversion of ethanol to ethylene.

Development of catalysts for chemical reactions driven by concentrated solar energy

International Nuclear Information System (INIS)

Berman, A.; Levitan, R.; Levy, M.

1992-03-01

The aim of this phase of the work is to study commercially available low priced catalysts, for the methanation and reforming processes in the closed-loop solar chemical heat pipe. This report summarized some long term tests of commercially available methanation catalysts and the measurement of their active surface before and after reaction. It was found that the 1%Ru on alumina stars catalysts (prepared by Englehard Company according to our request) is very active and stable at 350-750 C. The catalyst 'A' produced in Russia, is less active, however, did not lose the mechanical strength. The 50% Ni/SiO 2 catalyst is active as the 'A' catalyst but loses its activity after treatment at temperature > 600 C, its geometrical size shrinked. (authors). 25 refs., 25 figs., 36 tabs

Diethyl Ether Production Process with Various Catalyst Type

Directory of Open Access Journals (Sweden)

Widayat Widayat

2012-12-01

Full Text Available Several H-zeolite and HZSM-5 catalysts was preparated and their characters have also been investigated. H-zeolit Catalyst was preparated from Natural Zeolite that obtained from Malang District and Gunung Kidul District. Diethyl ether was produced by Ethanol with concentration of 95%. This research use fixed bed reactor that 1 gram of catalyst as bed catalyst, atmospheric pressure and temperature 140oC as the operating condition. Ethanol vapor from vaporization tank was driven by 200 ml/min Nitrogen stream. The responds in this research is liquid product concentration; diethyl ether, ethanol, methanol and water concentration. The results showed that the largest ethanol conversion was produced by the use of 56.44% HZSM-5 and the largest yield of diethyl ether diethyl was produced by the use of alumina and H-zeolite catalyst. The larger ratio between natural zeolite with HCl solvent will produce the larger surface area of catalyst and ethanol conversion. The largest ethanol conversion was produced at reactan ratio 1:20. [Keywords:  catalyst; ethanol conversion; dehydration process; yield of diethyl ether; natural zeolite].

Near-field radiative heat transfer in mesoporous alumina

International Nuclear Information System (INIS)

Li Jing; Feng Yan-Hui; Zhang Xin-Xin; Huang Cong-Liang; Wang Ge

2015-01-01

The thermal conductivity of mesoporous material has aroused the great interest of scholars due to its wide applications such as insulation, catalyst, etc. Mesoporous alumina substrate consists of uniformly distributed, unconnected cylindrical pores. Near-field radiative heat transfer cannot be ignored, when the diameters of the pores are less than the characteristic wavelength of thermal radiation. In this paper, near-field radiation across a cylindrical pore is simulated by employing the fluctuation dissipation theorem and Green function. Such factors as the diameter of the pore, and the temperature of the material are further analyzed. The research results show that the radiative heat transfer on a mesoscale is 2∼4 orders higher than on a macroscale. The heat flux and equivalent thermal conductivity of radiation across a cylindrical pore decrease exponentially with pore diameter increasing, while increase with temperature increasing. The calculated equivalent thermal conductivity of radiation is further developed to modify the thermal conductivity of the mesoporous alumina. The combined thermal conductivity of the mesoporous alumina is obtained by using porosity weighted dilute medium and compared with the measurement. The combined thermal conductivity of mesoporous silica decreases gradually with pore diameter increasing, while increases smoothly with temperature increasing, which is in good agreement with the experimental data. The larger the porosity, the more significant the near-field effect is, which cannot be ignored. (paper)

Noun complement clauses as referential modifiers

Directory of Open Access Journals (Sweden)

Carlos de Cuba

2017-01-01

Full Text Available A number of recent analyses propose that so-called noun complement clauses should be analyzed as a type of relative clause. In this paper, I present a number of complications for any analysis that equates noun complement clauses to relative clauses, and conclude that this type of analysis is on the wrong track. I present cross-linguistic evidence showing that the syntactic behavior of noun complement clauses does not pattern with relative clauses. Patterns of complementizer choice and complementizer drop as well as patterns involving main clause phenomena and extraction differ in the two constructions, which I argue is unexpected under a relative clause analysis that involves operator movement. Instead I present an alternative analysis in which I propose that the referentiality of a noun complement clause is linked to its syntactic behavior. Following recent work, I claim that referential clauses have a syntactically truncated left-periphery, and this truncation can account for the lack of main clause phenomena in noun complement clauses. I argue that the truncation analysis is also able to accommodate complementizer data patterns more easily than relative clause analyses that appeal to operator movement.

Confrontation clause

Directory of Open Access Journals (Sweden)

Tkachuk Sviatoslav

2016-07-01

Full Text Available The Sixth Amendment to the United States Constitution enumerates a cluster of rights granted to criminal defendants and is designed to make criminal prosecutions more accurate, fair, and legitimate. The Confrontation Clause, which states that „In all criminal prosecutions, the accused shall enjoy the right…to be confronted with the witness against him” should not be underestimated. This article seeks to analyse the evolution of the Confrontation Clause and the extent of a defendant’s right to face-to-face confrontation. The article analyse the case Crawford v. Washington, which was a key shift in the Supreme Court’s Confrontation Clause jurisprudence.

Productions of sunflower oil biodiesel and used cooking oil through heterogeneous catalysts compared to conventional homogeneous catalysts

International Nuclear Information System (INIS)

Gutiérrez-Zapata, C A; Collazos, C A; Acuña, H E Castellanos; Fernandez, C P; Martínez, D Blanco; Cuervo, J A

2017-01-01

This document compares homogeneous and heterogeneous catalysts used by production of biodiesel of sunflower oil and cooking oil used in frying. For this, NaOH was used as a catalyst homogeneous, and K 2 CO 3 and Na 2 CO 3 supported in gamma-alumina (K 2 CO 3 /γ Al 2 O 3 y Na 2 CO 3 /γ-Al 2 O 3 ) were synthesized as heterogeneous catalysts, which were characterized by X-ray diffraction. The transesterification tests were carried out for the sunflower oil and used cooking oil, in a reflux system, to different molar relations methanol/oil, depending on the type of oil and characterization of the same. The reflux system is performed at a temperature of 55-60°C for one hour. Finally, biofuel was characterized and the yield of the reaction was calculated. (paper)

Productions of sunflower oil biodiesel and used cooking oil through heterogeneous catalysts compared to conventional homogeneous catalysts

Science.gov (United States)

Gutiérrez-Zapata, C. A.; Blanco Martínez, D.; Collazos, C. A.; Castellanos Acuña, H. E.; Cuervo, J. A.; Fernandez, C. P.

2017-01-01

This document compares homogeneous and heterogeneous catalysts used by production of biodiesel of sunflower oil and cooking oil used in frying. For this, NaOH was used as a catalyst homogeneous, and K2CO3 and Na2CO3 supported in gamma-alumina (K2CO3/γ Al2O3 y Na2CO3 /γ-Al2O3) were synthesized as heterogeneous catalysts, which were characterized by X-ray diffraction. The transesterification tests were carried out for the sunflower oil and used cooking oil, in a reflux system, to different molar relations methanol/oil, depending on the type of oil and characterization of the same. The reflux system is performed at a temperature of 55-60°C for one hour. Finally, biofuel was characterized and the yield of the reaction was calculated.

Influence of the acid and basic properties of rhenium oxide supported on alumina catalyst on the catalytic performance in olefin metathesis; Influence des proprietes acido-basiques de l`oxyde de rhenium supporte sur les performances catalytiques en metathese des olefines

Energy Technology Data Exchange (ETDEWEB)

Nahama, F.

1996-11-30

The aim of this work is to study the influence of the acid-basic properties of rhenium oxide supported on alumina catalyst on the catalytic performance in olefin metathesis. The literature data indicate that the environment of the active site does possess acid properties. However, the nature of the acid sites is still matter of debate. Concerning the Re O{sub x} - Al{sub 2}O{sub 3} interactions, we have shown that perrhenate ions are electrostatically absorbed on alumina. The uptake of rhenium is favoured at acidic pH (below 4), and the absorbed rhenium is in equilibrium with rhenium in solution. The results of rhenium extraction by water strongly suggest that the surface compounds of the calcined Re{sub 2}O{sub 7}/Al{sub 2}O{sub 3} materials is aluminium perrhenate. Characterization of surface acidity of the catalyst by infrared spectroscopy reveals that the initiation of the metathesis reaction is governed essentially by Lewis acidity. This strongly supports the role of Lewis acidity, which is exalted by the increase of the rhenium content and the calcination temperature. Finally, we point out by ammonia adsorption-thermodesorption a band at 1320 cm{sup -1} characteristic of the Lewis acidity of aluminium perrhenate. This result is a second indication of the presence of aluminium perrhenate on the Re{sub 2}O{sub 7}/Al{sub 2}O{sub 3} catalyst surface. (author)

Method and apparatus for combination catalyst for reduction of NO.sub.x in combustion products

Science.gov (United States)

Socha, Richard F.; Vartuli, James C.; El-Malki, El-Mekki; Kalyanaraman, Mohan; Park, Paul W.

2010-09-28

A method and apparatus for catalytically processing a gas stream passing therethrough to reduce the presence of NO.sub.x therein, wherein the apparatus includes a first catalyst composed of a silver containing alumina that is adapted for catalytically processing the gas stream at a first temperature range, and a second catalyst composed of a copper containing zeolite located downstream from the first catalyst, wherein the second catalyst is adapted for catalytically processing the gas stream at a lower second temperature range relative to the first temperature range.

Controlled metal nitrate decomposition for the preparation of supported metal Catalysts

NARCIS (Netherlands)

Wolters, M.

2010-01-01

High surface area supported metal (oxide) catalysts are essential for the production of fuels, chemicals, pharmaceuticals and the abatement of environmental pollution. Impregnation of high surface area supports, often silica or alumina, followed by drying, calcination and reduction is one of the

Copper (0) nanoparticles onto silica: A stable and facile catalyst for ...

Indian Academy of Sciences (India)

Abstract. Solid supported copper (0) nanoparticles were prepared by physical adsorption of copper (0)nanoparticles (synthesized through bottom-up approach) on the solid supports such as silica, HAP, cellulose andbasic alumina. Studies comparing these supported catalysts were done with the synthesis of ...

Phosphorus poisoning of molybdenum sulfide hydrodesulfurization catalysts supported on carbon and alumina

NARCIS (Netherlands)

Bouwens, S.M.A.M.; Vissers, J.P.R.; Beer, de V.H.J.; Prins, R.

1988-01-01

Phosphorus-containing Mo sulfide catalysts supported on ¿-Al2O3 and activated carbon were evaluated for their thiophene HDS activities. Phosphorus was added as phosphoric acid to the carrier material prior to the molybdenum component. The thiophene HDS activity of the carbon-supported catalysts was

Micelle-derived catalysts for extended Schulz-Flory. Technical progress report, July 1, 1986--September 30, 1986

Energy Technology Data Exchange (ETDEWEB)

Abrevaya, H.

1986-12-31

The objective of this program is to develop a synthesis gas conversion catalyst with higher selectivity to liquid fuels, while maintaining catalytic activity and stability at least equivalent relative to state-of-the-art precipitated iron catalysts. During this quarter, the emphasis in the program has been the investigation of the hydrocarbon cutoff hypothesis with supported ruthenium catalysts. An alumina-supported catalyst with smaller than 20{Angstrom} ruthenium particles was tested under conditions of maximal water gas shift activity. During this test more than 90% of the water made in the Fischer-Tropsch synthesis reaction was converted to H{sub 2}. However, the extent of ruthenium metal agglomeration was not reduced. Accordingly, it was not possible to conclude whether hydrocarbon cutoff occurs with smaller than 20{Angstrom} ruthenium particles on {gamma}-alumina. A ruthenium catalyst prepared on Y-type zeolite had 20{Angstrom} or smaller ruthenium particles according to STEM examination and a 15{Angstrom} average ruthenium metal particle size according to EXAFS examination. The ruthenium metal particle size was stable during the test with this catalyst. The hydrocarbon product distribution was Anderson-Schulz-Flory with no cutoff up to a carbon number of 160. A well-dispersed titania-supported ruthenium catalyst is going to be evaluated during the next quarter in order to determine whether hydrocarbon cutoff occurs.

Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

Science.gov (United States)

Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

2014-12-01

Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.

Insights into the chemistry of the Claus reaction furnace and waste heat boiler

International Nuclear Information System (INIS)

Clark, P.D.; Dowling, N.I.; Huang, M.

1997-01-01

Methods to deal with the unwanted by-product of acid-gas combustion in the Claus reaction furnace were presented. The by-product, carbon disulfide (CS 2 ), is disturbing because if it is not converted to H 2 S in the first catalytic converter, it will appear as a sulfur emission in the tail gas of plants not using reductive clean-up technology. To address this issue, Claus catalysts have been designed specifically for CS 2 hydrolysis. Studies have been conducted to determine what type of hydrocarbons lead to CS 2 formation. It was concluded that all hydrocarbons result in CS 2 production, but that benzene is particularly difficult. Data for a wide range of acid gas compositions and contaminant hydrocarbons at different process conditions was presented. Methods to destroy CS 2 in the furnace were also identified

Preparation and Properties of Pt-Mo Sulfide System Supported on Mesoporous Silica-Alumina

Czech Academy of Sciences Publication Activity Database

Gulková, Daniela; Vít, Zdeněk

2006-01-01

Roč. 162, - (2006), s. 489-496 ISSN 0167-2991. [International Symposium Scienctific Bases for Heterogeneous Catalysts /9./. Louvain-la-Neuve, 10.09.2006-14.09.2006] R&D Projects: GA ČR(CZ) GA104/06/0870 Institutional research plan: CEZ:AV0Z40720504 Keywords : silica-alumina * Pt-Mo * hydrotreating Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.307, year: 2005

Diethyl Ether Production Process with Various Catalyst Type

Directory of Open Access Journals (Sweden)

Widayat

2013-01-01

Full Text Available Several H-zeolite and HZSM-5 catalysts was preparated and their characters have also been investigated. H-zeolit Catalyst was preparated from Natural Zeolite that obtained from Malang District and Gunung Kidul District. Diethyl ether was produced by Ethanol with concentration of 95%. This research use fixed bed reactor that 1 gram of catalyst as bed catalyst, atmospheric pressure and temperature 140oC as the operating condition. Ethanol vapor from vaporization tank was driven by 200 ml/min Nitrogen stream. The responds in this research is liquid product concentration; diethyl ether, ethanol, methanol and water concentration. The results showed that the largest ethanol conversion was produced by the use of 56.44% HZSM-5 and the largest yield of diethyl ether diethyl was produced by the use of alumina and H-zeolite catalyst. The larger ratio between natural zeolite with HCl solvent will produce the larger surface area of catalyst and ethanol conversion. The largest ethanol conversion was produced at reactan ratio 1:20.

Activity and selectivity of three molybdenum catalysts for coal liquefaction reactions

Energy Technology Data Exchange (ETDEWEB)

Curtis, C.W.; Pellegrino, J.L.

The activity and selectivity of three different molybdenum catalysts for reactions occurring in coal liquefaction, specifically for hydrogenation (HYD), hydrodeoxygenation (HDO), hydrodenitrogenation (HDN), hydrodesulfurization (HDS), and hydrocracking (HYC), have been examined. The three molybdenum catalysts used were molybdenum napthenate, molybdenum on ..gamma..-alumina, and a precipitated, disordered MoS/sub 2/. Molybdenum naphthenate was most selective for HYD and HDN. All three catalysts exhibited approximately equal activity for HDS and HDO and little selectivity for HYC of alkyl bridge structures. The activity and selectivity of the three molybdenum catalysts for producing hydrocarbons and removing heteroatoms from coal during liquefaction were determined and compared. Molybdenum naphthenate was the most active catalyst for hydrocarbon production and removal of nitrogen- and oxygen-containing species during coal liquefaction. 31 refs., 4 figs., 7 tabs.

Fructose dehydration to 5-hydroxymethylfurfural over solid acid catalysts in a biphasic system

NARCIS (Netherlands)

Ordomskiy, V.; Schouten, J.C.; Schaaf, van der J.; Nijhuis, T.A.

2012-01-01

Different acidic heterogeneous catalysts like alumina, aluminosilicate, zirconium phosphate, niobic acid, ion-exchange resin Amberlyst-15, and zeolite MOR have been studied in fructose dehydration to 5-hydroxymethylfurfural (HMF). The acidity of these materials was characterized using

Some problems of manufacturing and industrial application of CoMo-Al2O3 catalyst

International Nuclear Information System (INIS)

Walendziewski, J.

1991-01-01

The monograph presents results of studies of some selected problems relating to CoMo-Al 2 O 3 catalyst: method of production alumina support and catalyst; application of catalyst in the selected hydro refining processes; physicochemical properties of the used catalyst; reclamation of metal compounds from the spent catalyst. Results of investigations of catalyst preparation illustrate how the physicochemical properties of alumina support and catalyst, mainly porous structure could be controlled by the selection of raw materials and parameters of aluminum hydroxide precipitation, method of forming and calcination temperature of support. Application of the catalyst of modified porous structure has shown its high activity in hydro refining process of light cracking catalytic oil (over 95% hydrodesulphurization) and mild hydro cracking process of vacuum gas oil (sulphur content in product below 0.03% wt.). As an effect of studying of hydro refining process of aromatic hydrocarbon fraction it has been found that H 2 S concentration in reaction mixture is the main factor influencing process selectivity. Some effect on the selectivity exerts also other process parameters and chemical composition of the catalyst - cobalt molybdenum content ratio and promoters content. Long term exploitation of the domestic CoMo-Al 2 O 3 catalyst in hydrodesulphurization process indicates its satisfied thermal stability although results in deteriorating of mechanical resistance, lowering of specific surface area, increase in mean pore radius and decrease in acidity of catalyst. In the last chapter of the monograph the results of investigations of reclamation of metal compounds (molybdic acid, aluminum hydroxide, cobalt carbonate) from the spent catalyst as well as an original technology of manufacture of the fresh one using these compounds have been presented. (author). 338 refs, 31 figs, 32 tabs

4,6-Dimethyl-dibenzothiophene conversion over Al{sub 2}O{sub 3}-TiO{sub 2}-supported noble metal catalysts

Energy Technology Data Exchange (ETDEWEB)

Nunez, Sara [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Vicentina, Iztapalapa, 09340, Mexico, D.F. (Mexico); Escobar, Jose, E-mail: jeaguila@imp.mx [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, San Bartolo Atepehuacan, Gustavo A. Madero, 07730, Mexico, D.F. (Mexico); Vazquez, Armando; Reyes, Jose Antonio de los [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Vicentina, Iztapalapa, 09340, Mexico, D.F. (Mexico); Hernandez-Barrera, Melissa [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, San Bartolo Atepehuacan, Gustavo A. Madero, 07730, Mexico, D.F. (Mexico)

2011-03-15

Research highlights: {yields} Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-TiO{sub 2} (molar ratio Al/Ti = 2, AT2) mixed oxides were pore-filling impregnated to obtain Pd, Pt and Pd-Pt catalysts with {approx}1 wt% nominal metal loading. {yields} Reduced catalysts were tested in the 4,6-dimethyl-dibenzothiophene hydrodesulfurization (HDS). {yields} In Pd-containing materials, TiO{sub 2} incorporation into the alumina support was favorable to the catalytic activity of noble metal catalysts. {yields} Enhanced intrinsic activity (per exposed metallic site) was obtained in Pt-containing catalysts supported on the AT2 mixed oxide. {yields} Yield to different products over various catalysts seemed to be strongly influenced by metallic particles dispersion. - Abstract: Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-TiO{sub 2} (molar ratio Al/Ti = 2, AT2) mixed oxides were synthesized using a low-temperature sol-gel method and were further pore-filling impregnated to obtain Pd and Pt catalysts with {approx}1 wt% nominal metal loading. Simultaneous impregnation was used to prepare bimetallic materials at Pd:Pt = 80:20. Solids characterization was carried out by N{sub 2}-physisorption, high-resolution transmission electron microscopy (HR-TEM and E-FTEM), X-ray diffraction, temperature-programmed reduction and CO-chemisorption. Reduced (350 deg. C, H{sub 2} flow) catalysts were tested in the 4,6-dimethyl-dibenzothiophene hydrodesulfurization (HDS) (in n-dodecane, at 300 deg. C and 5.5 MPa, batch reactor). In Pd-containing materials, TiO{sub 2} incorporation into the alumina support was favorable to the catalytic activity of noble metal catalysts, where bimetallic Pd-Pt with AT2 carrier had the highest organo-S compound conversion. Enhanced intrinsic activity (per exposed metallic site) was obtained in Pt-containing catalysts supported on the AT2 mixed oxide (as compared to alumina-supported ones). Yield to different products over various catalysts seemed to be strongly influenced by

Influence of coprecipitation and mechanical mixture methods on the characteristics of nickel oxide-alumina composites; Influencia dos metodos de coprecipitacao e mistura mecanica nas caracteristicas de compositos oxido de niquel-alumina

Energy Technology Data Exchange (ETDEWEB)

Cordeiro, G.L.; Yoshito, W.K.; Ussui, V.; Lima, N.B. de; Lazar, D.R.R., E-mail: gcordeiro@usp.br [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

2014-07-01

Alumina-supported nickel catalysts are currently used in the reforming process due to low cost and high activity for hydrogen production from alcohols. In this work, the effect of preparation methods on nickel oxide-alumina based materials has been investigated. Nickel content was fixed at 15 wt%. Ceramic powders were obtained by coprecipitation in ammonia medium and mechanical mixture. Coprecipitated materials were calcined in air at 750 deg C to obtain the corresponding oxides. Materials obtained by mechanical mixture were prepared by wet milling of nickel oxide and alumina powders, both synthesized by precipitation and calcination in air at 450 and 750 deg C, respectively. Powders were characterized by X-ray diffraction, nitrogen gas sorption by applying the BET method, laser diffraction, scanning electron microscopy, electrophoretic mobility measurements for zeta potential determination and infrared spectroscopy. The results showed that coprecipitation method allowed the production of mixed oxides with high surface area (232,7 ± 3,2 m{sup 2}.g{sup -1}) and normal granulometric distribution while mechanical mixture led to the formation of materials constituted by gamma alumina and nickel oxide phases, with low surface area (136,2 ± 0,5 m{sup 2}.g{sup -1}) and bimodal granulometric distribution. (author)

Hydrogenation of carbon monoxide over supported palladium catalysts

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, K.; Hashimoto, H.; Kunugi, T.

1978-03-01

An alumina-supported 2% palladium catalyst had higher activity for carbon monoxide hydrogenation than a silica-supported 2% palladium catalyst, at 250/sup 0/-400/sup 0/C and 1 atm. The addition of lanthanum oxide or thorium oxide, but not of potassium oxide, to the silica-supported catalyst increased the conversion at 350/sup 0/C from 1.1% to 81.0% with a selectivity of 56.1% for methane, 1.4% for C/sub 2/ compounds, 0.1% for C/sub 3/ compounds, and 42.5% for carbon dioxide. Temperature-programed desorption of carbon monoxide in a hydrogen stream showed that of two desorption peaks observed for carbon monoxide, the one at higher temperature corresponded to the carbon monoxide species which hydrogenates to methane and that the area of this peak increased with increasing thorium content of the catalyst. Graphs, tables, and 12 references.

Dynamic tensile response of alumina-Al composites

International Nuclear Information System (INIS)

Atisivan, R.; Bandyopadhyay, A.; Gupta, Y. M.

2002-01-01

Plate impact experiments were carried out to examine the high strain-rate tensile response of alumina-aluminum (Al) composites with tailored microstructures. A novel processing technique was used to fabricate interpenetrating phase alumina-aluminum composites with controlled microstructures. Fused deposition modeling (FDM), a commercially available rapid prototyping technique, was used to produce the controlled porosity mullite ceramic preforms. Alumina-Al composites were then processed via reactive metal infiltration of porous mullite ceramics. With this approach, both the micro as well as the macro structures can be designed via computer aided design (CAD) to tailor the properties of the composites. Two sets of dynamic tensile experiments were performed. In the first, the metal content was varied between 23 and 39 wt. percent. In the second, the microstructure was varied while holding the metal content nearly constant. Samples with higher metal content, as expected, displayed better spall resistance. For a given metal content, samples with finer metal diameter showed better spall resistance. Relationship of the microstructural parameters on the dynamic tensile response of the structured composites is discussed here

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

Science.gov (United States)

Islam, A. E.; Nikolaev, P.; Amama, P. B.; Zakharov, D.; Sargent, G.; Saber, S.; Huffman, D.; Erford, M.; Semiatin, S. L.; Stach, E. A.; Maruyama, B.

2015-09-01

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only in the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. With the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.

Characterization of Catalyst Materials for Production of Aerospace Fuels

Science.gov (United States)

Best, Lauren M.; De La Ree, Ana B.; Hepp, Aloysius F.

2012-01-01

Due to environmental, economic, and security issues, there is a greater need for cleaner alternative fuels. There will undoubtedly be a shift from crude oil to non-petroleum sources as a feedstock for aviation (and other transportation) fuels. Additionally, efforts are concentrated on reducing costs coupled with fuel production from non-conventional sources. One solution to this issue is Fischer-Tropsch gas-to-liquid technology. Fischer-Tropsch processing of synthesis gas (CO/H2) produces a complex product stream of paraffins, olefins, and oxygenated compounds such as alcohols and aldehydes. The Fisher-Tropsch process can produce a cleaner diesel oil fraction with a high cetane number (typically above 70) without any sulfur or aromatic compounds. This process is most commonly catalyzed by heterogeneous (in this case, silver and platinum) catalysts composed of cobalt supported on alumina or unsupported alloyed iron powders. Physisorption, chemisorptions, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) are described to better understand the potential performance of Fischer-Tropsch cobalt on alumina catalysts promoted with silver and platinum. The overall goal is to preferentially produce C8 to C18 paraffin compounds for use as aerospace fuels. Progress towards this goal will eventually be updated and achieved by a more thorough understanding of the characterization of catalyst materials. This work was supported by NASA s Subsonic Fixed Wing and In-situ Resource Utilization projects.

Catalytic reforming of glycerol in supercritical water over bimetallic Pt-Ni catalyst

NARCIS (Netherlands)

Chakinala, A.G.; van Swaaij, Willibrordus Petrus Maria; Kersten, Sascha R.A.; de Vlieger, Dennis; Seshan, Kulathuiyer; Brilman, Derk Willem Frederik

2013-01-01

Catalytic reforming of pure glycerol for the production of hydrogen at low temperature and short residence times in supercritical water was investigated using a bimetallic Pt–Ni catalyst supported on alumina. Initial tests were carried out to study the reforming activity of bimetallic Pt–Ni

Aza-Michael Mono-addition Using Acidic Alumina under Solventless Conditions

Directory of Open Access Journals (Sweden)

Giovanna Bosica

2016-06-01

Full Text Available Aza-Michael reactions between primary aliphatic and aromatic amines and various Michael acceptors have been performed under environmentally-friendly solventless conditions using acidic alumina as a heterogeneous catalyst to selectively obtain the corresponding mono-adducts in high yields. Ethyl acrylate was the main acceptor used, although others such as acrylonitrile, methyl acrylate and acrylamide were also utilized successfully. Bi-functional amines also gave the mono-adducts in good to excellent yields. Such compounds can serve as intermediates for the synthesis of anti-cancer and antibiotic drugs.

Biodiesel production using heterogeneous catalysts including wood ash and the importance of enhancing byproduct glycerol purity

International Nuclear Information System (INIS)

Uprety, Bijaya K.; Chaiwong, Wittavat; Ewelike, Chinomnso; Rakshit, Sudip K.

2016-01-01

Highlights: • Comparison of biodiesel production using homogeneous and heterogeneous catalysts. • Comparative study of CaO and CaO supported on alumina for biodiesel production. • Tradeoff between biodiesel conversion rate and purity. • Ash from birch bark and wood pellet industry explored as a potential catalyst. - Abstract: Transesterification of vegetable oils or animal fats with methanol in the presence of catalysts produces fatty acid methyl esters (FAME) and glycerol as a co-product. This study was focused on a comparative study of the transesterification of refined, bleached and deodorized palm oil (RBD palm oil) using a heterogeneous catalysts CaO with and without γ-alumina (γ-Al_2O_3) as a support. The results were also compared to that using sodium hydroxide (NaOH), which is a homogenous catalyst. Parameters like the amount of catalyst, the molar ratio of methanol to oil, reaction time and reaction temperature that affect methyl ester and glycerol formation were analyzed and the optimum conditions were determined. The FAME and glycerol content (96.75% and 92.73% respectively) obtained using CaO were lower in purity compared to that using CaO/Al_2O_3 (97.66% and 96.36% respectively). In the second phase of our work, wood ash from two different sources (birch bark & flyash from a biomass based power plant), which were calcined at 800 °C were studied for their potential use as a cheap renewable alternative heterogeneous catalyst. Both the wood ash samples were found to have good potential for use in such production process, but needs to be optimized further to obtain biodiesel which meets fuel biodiesel specifications. Both CaO and CaO supported on alumina produces FAME to levels that meet the fuel specifications required for blending with diesel. However, the latter produces a purer form of byproduct glycerol that can be easily converted to value added products, without the need for purification. On this basis the supported catalyst is

Catalytic oxidation of volatile organic compounds (n-hexane, benzene, toluene, o-xylene promoted by cobalt catalysts supported on γ-Al2O3-CeO2

Directory of Open Access Journals (Sweden)

R. Balzer

2014-09-01

Full Text Available Cobalt catalysts supported on γ-alumina, ceria and γ-alumina-ceria, with 10 or 20%wt of cobalt load, prepared by the wet impregnation method and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, field emission transmission electron microscopy (FETEM, N2 adsorption-desorption isotherms (BET/BJH methods, energy-dispersive X-ray spectroscopy (EDX, X-ray photoemission spectroscopy (XPS, O2-chemisorption and temperature programmed reduction (TPR were used to promote the oxidation of volatile organic compounds (n-hexane, benzene, toluene and o-xylene. For a range of low temperatures (50-350 °C, the activity of the catalysts with a higher cobalt load (20% wt was greater than that of the catalysts with a lower cobalt load (10% wt. The Co/γ-Al2O3-CeO2 catalytic systems presented the best performances. The results obtained in the characterization suggest that the higher catalytic activity of the Co20/γ-Al2O3-CeO2 catalyst may be attributed to the higher metal content and amount of oxygen vacancies, as well as the effects of the interaction between the cobalt and the alumina and cerium oxides.

Cobalt and KNO{sub 3} supported on alumina catalysts for diesel soot combustion

Energy Technology Data Exchange (ETDEWEB)

Grzona, Claudia B. [25 de mayo 284, INTEQUI-CONICET-UNSL, Facultad de Ingenieria y Ciencias Economico-Sociales, Villa Mercedes, 5730 (Argentina); Lick, Ileana D. [Calle 47 No 257, CINDECA (CCT-LaPlata-CONICET-UNLP), Departamento de Quimica, Facultad de Ciencias Exactas, La Plata, 1900 (Argentina); Castellon, Enrique Rodriguez [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, Malaga, 29071 (Spain); Ponzi, Marta I. [25 de mayo 284, INTEQUI-CONICET-UNSL, Facultad de Ingenieria y Ciencias Economico-Sociales, Villa Mercedes, 5730 (Argentina); Ponzi, Esther N., E-mail: eponzi@quimica.unlp.edu.ar [Calle 47 No 257, CINDECA (CCT-LaPlata-CONICET-UNLP), Departamento de Quimica, Facultad de Ciencias Exactas, La Plata, 1900 (Argentina)

2010-10-01

The catalytic combustion of diesel soot was studied in the presence of fresh and aged catalysts: Co/Al{sub 2}O{sub 3}, KNO{sub 3}/Al{sub 2}O{sub 3} and Co/KNO{sub 3}/Al{sub 2}O{sub 3}. The catalysts were prepared by impregnation using nitrate solutions. The catalysts were characterized by X-ray diffraction, thermal programmed reduction, vibrational spectroscopy and X-ray photoelectron spectroscopy. Fresh and aged catalysts present high activity in presence of O{sub 2} and O{sub 2}/NO. The values of the combustion temperature decrease more than 200 deg. C with respect to that observed in the process without catalysis. The activity is associated with the presence of KNO{sub 3} and the role of this salt can be attributed to the contribution of NO{sub 3}{sup -}/NO{sub 2}{sup -} redox cycle.

Development of low light-off catalyst; Teion kassei ni sugureta shokubai no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Takemoto, T; Ichikawa, S; Koda, Y; Yamamoto, E; Sumida, H; Yamada, H; Shigetsu, M; Komatsu, K [Mazda Motor Corp., Tokyo (Japan)

1997-10-01

A new type of three way catalyst was developed in order to reduce HC, CO and NOx in cold exhaust gas. This catalyst consists of double layer, and has a base support material of alumina and oxygen storage components (OSC) loaded with active metals including platinum. palladium and rhodium. It has good light-off performance and high catalytic activity. This catalyst includes two types of OSC. One is CeO2, and the other is CePrO2 that makes possible to improve NOx conversion at high exhaust gas temperature. 8 refs., 13 figs., 2 tabs.

Support effects on hydrotreating activity of NiMo catalysts

International Nuclear Information System (INIS)

Dominguez-Crespo, M.A.; Arce-Estrada, E.M.; Torres-Huerta, A.M.; Diaz-Garcia, L.; Cortez de la Paz, M.T.

2007-01-01

The effect of the gamma alumina particle size on the catalytic activity of NiMoS x catalysts prepared by precipitation method of aluminum acetate at pH = 10 was studied. The structural characterization of the supports was measured by using XRD, pyridine FTIR-TPD and nitrogen physisorption. NiMo catalysts were characterized during the preparation steps (annealing and sulfidation) using transmission electron microscopy (TEM). Hydrogen TPR studies of the NiMo catalysts were also carried out in order to correlate their hydrogenating properties and their catalytic functionality. Catalytic tests were carried out in a pilot plant at 613, 633 and 653 K temperatures. The results showed that the rate constants of hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatizing (HDA) at 613-653 K decreased in the following order: A > B > C corresponding to the increase of NiMoS particle size associated to these catalysts

The synthesis of nanostructured, phase pure catalysts by hydrodynamic cavitation

Energy Technology Data Exchange (ETDEWEB)

Moser, W.R.; Sunstrom, J.E.; Marshik-Geurts, B.J. [Worcester Polytechnic Institute, Worcester, MA (United States)

1995-12-01

A new process for the synthesis of advanced catalytic materials based on performing the synthesis under hydrodynamic cavitation conditions has been discovered. This continuous process for catalyst synthesis resulted in the formation of both supported and unsupported catalysts. The advantage of the process over classical methods of synthesis is that it permits the formation of a wide variety of nanostructured catalysts in exceptionally high phase purities. The synthesis of platinum and palladium catalysts supported on alumina and other supports resulted in high dispersions of the noble metals. The synthesis of alpha, beta- and gamma-bismuth molybdates resulted in catalysts having superior phase purities as compared to several other classical methods of synthesis. The beta-bismuth molybdate was synthesized directly onto Cabosil. These studies showed that the particle size of the active component could be varied from a few manometers to much larger grains. The process enabled the synthesis of other complex metal oxides like perovskites as pure phases. The process uses a commercially available Microfluidizer.

Vertical single- and double-walled carbon nanotubes grown from modified porous anodic alumina templates

International Nuclear Information System (INIS)

Maschmann, Matthew R; Franklin, Aaron D; Amama, Placidus B; Zakharov, Dmitri N; Stach, Eric A; Sands, Timothy D; Fisher, Timothy S

2006-01-01

Vertical single-walled and double-walled carbon nanotube (SWNT and DWNT) arrays have been grown using a catalyst embedded within the pore walls of a porous anodic alumina (PAA) template. The initial film structure consisted of a SiO x adhesion layer, a Ti layer, a bottom Al layer, a Fe layer, and a top Al layer deposited on a Si wafer. The Al and Fe layers were subsequently anodized to create a vertically oriented pore structure through the film stack. CNTs were synthesized from the catalyst layer by plasma-enhanced chemical vapour deposition (PECVD). The resulting structure is expected to form the basis for development of vertically oriented CNT-based electronics and sensors

Enhanced gasification of wood in the presence of mixed catalysts

Energy Technology Data Exchange (ETDEWEB)

Weber, S. L.; Mudge, L. K.; Sealock, Jr., L. J.; Robertus, R. J.; Mitchell, D. E.

Experimental results obtained in laboratory investigations of steam gasification of wood in the presence of mixed catalysts are presented. These studies are designed to test the technical feasibility of producing specific gaseous products from wood by enhancing its reactivity and product specificity through the use of combined catalysts. The desired products include substitute natural gas, hydrocarbon synthesis gas and ammonia synthesis gas. The gasification reactions are controlled through the use of specific catalyst combinations and operating parameters. A primary alkali carbonate gasification catalyst impregnated into the wood combined with specific commercially available secondary catalysts produced the desired products. A yield of 50 vol % methane was obtained with a randomly mixed combination of a commercial nickel methanation catalyst and silica-alumina cracking catalyst at a weight ratio of 3:1 respectively. Steam gasification of wood in the presence of a commercial Si-Al cracking catalyst produced the desired hydrocarbon synthesis gas. Hydrogen-to-carbon monoxide ratios needed for Fischer-Tropsch synthesis of hydrocarbons were obtained with this catalyst system. A hydrogen-to-nitrogen ratio of 3:1 for ammonia synthesis gas was achieved with steam-air gasification of wood in the presence of catalysts. The most effective secondary catalyst system employed to produce the ammonia synthesis gas included two commercially prepared catalysts formulated to promote the water-gas shift reaction.

Bio diesel Production via Transesterification of Palm Oil Using NaOH/ Al2O3 Catalysts

International Nuclear Information System (INIS)

Taufiq Yap Yun Hin; Nurul Fitriyah Abdullah; Mahiran Basri; Taufiq Yap Yun Hin; Nurul Fitriyah Abdullah

2011-01-01

Due to the increase in price of petroleum and environmental concerns, the search for alternative fuels has gained importance. In this work, bio diesel production by transesterification of palm oil with methanol has been studied in a heterogeneous system using sodium hydroxide loaded on alumina (NaOH/ Al 2 O 3 ). NaOH/ Al 2 O 3 catalyst was prepared by impregnation of alumina with different amount of an aqueous solution of sodium hydroxide followed by calcination in air for 3 h. The prepared catalysts were then characterized by using x-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunner-Emmett-Teller surface area measurement (BET), scanning electron microscopy (SEM) and temperature-programmed desorption of CO 2 (CO 2 -TPD). Moreover, the dependence of the conversion of palm oil on the reactions variables such as the molar ratio of methanol/oil, the amount of catalysts used, reaction temperatures and reaction times were performed. The conversion of 99 % was achieved under the optimum reaction conditions. The bio diesel obtained was characterized by FT-IR and the pour point was measured. (author)

Sulphur poisoning of palladium catalysts used for methane combustion: Effect of the support

International Nuclear Information System (INIS)

Escandon, Lara S.; Ordonez, Salvador; Vega, Aurelio; Diez, Fernando V.

2008-01-01

Four different supported palladium catalysts (using alumina, silica, zirconia and titania as supports), prepared by incipient wetness impregnation, were tested as catalysts for methane oxidation in presence of sulphur dioxide. The catalyst supported on zirconia showed the best performance, whereas the silica-supported one showed the fastest deactivation. Temperature-programmed desorption experiments of the poisoned catalysts suggest that SO 2 adsorption capacity of the support plays a key role in the catalyst poisoning. In order to study the effect of promoters, expected to improve the thermal stability and thioresistance of the catalyst, commercial zirconia modified by yttrium and lantane was tested as supports. It was found that the presence of these promoters does not improve the performance of the zirconia-supported catalyst. A deactivation model - considering two different active sites (fresh and poisoning), pseudo-first order dependence on methane concentration and poisoning rate depending on sulphur concentration and fraction of non-poisoned palladium - was used for modelling the deactivation behaviour

Constraint Specialisation in Horn Clause Verification

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick

2015-01-01

We present a method for specialising the constraints in constrained Horn clauses with respect to a goal. We use abstract interpretation to compute a model of a query-answer transformation of a given set of clauses and a goal. The effect is to propagate the constraints from the goal top......-down and propagate answer constraints bottom-up. Our approach does not unfold the clauses at all; we use the constraints from the model to compute a specialised version of each clause in the program. The approach is independent of the abstract domain and the constraints theory underlying the clauses. Experimental...

Deactivation by carbon of iron catalysts for indirect liquefaction

Energy Technology Data Exchange (ETDEWEB)

Bartholomew, C.H.

1990-10-11

This report describes recent progress in a fundamental, three-year investigation of carbon formation and its effects on the activity and selectivity of promoted iron catalysts for Fischer-Tropsch (FT) synthesis, the objectives of which are: determine rates and mechanisms of carbon deactivation of unsupported Fe and Fe/K catalysts during CO hydrogenation over a range of CO concentrations, CO:H{sub 2} ratios, and temperatures; model the rates of deactivation of the same catalysts in fixed-bed reactors. During the thirteenth quarter design of software for a computer-automated reactor system to be used in the kinetic and deactivation studies was continued. Further progress was made toward the completion of the control language, control routines, and software for operating this system. Progress was also made on the testing of the system hardware and software. H{sub 2} chemisorption capacities and activity selectivity data were also measured for three iron catalysts promoted with 1% alumina. 47 refs., 8 figs., 1 tab.

Aqueous phase reforming of ethylene glycol - Role of intermediates in catalyst performance

NARCIS (Netherlands)

de Vlieger, Dennis; Mojet, Barbara; Lefferts, Leonardus; Seshan, Kulathuiyer

2012-01-01

Liquid product formation during the aqueous catalytic reforming of ethylene glycol (EG) was studied up to 450 °C and 250 bar pressure. Methanol, ethanol, and acetic acid were the main liquid by-products during EG reforming in the presence of alumina-supported Pt and Pt–Ni catalysts. The effect of

Selective oxidation of methane to ethane and ethylene over various oxide catalysts

NARCIS (Netherlands)

Roos, J.A.; Bakker, A.G.; Bosch, H.; van Ommen, J.G.; Ross, J.R.H.

1987-01-01

Preliminary results are reported for the oxidative coupling of methane to give ethane/ethylene mixtures over a series of different catalyst formulations; the temperature range studied is 650–850°C. A comparison is made of the behaviour of lead/alumina and lithium/magnesia materials. It is found that

Process and catalysts for hydrocarbon conversion. [high antiknock motor fuel

Energy Technology Data Exchange (ETDEWEB)

1940-02-14

High anti-knock motor fuel is produced from hydrocarbons by subjecting it at an elevated temperature to contact with a calcined mixture of hydrated silica, hydrated alumina, and hydrated zirconia, substantially free from alkali metal compounds. The catalyst may be prepared by precipitating silica gel by the acidification of an aqueous solution of an alkali metal silicate, intimately mixing hydrated alumina and hydrated zirconia therewith, drying, purifying the composite to substantially remove alkali metal compounds, again drying, forming the dried material into particles, and finally calcining. The resultant conversion products may be fractionated to produce gasoline, hydrocarbon oil above gasoling boiling point range, and a gaseous fraction of olefins which are polymerized into gasoline boiling range polymers.

Catalysts at work: From integral to spatially resolved X-ray absorption spectroscopy

DEFF Research Database (Denmark)

Grunwaldt, Jan-Dierk; Kimmerle, B.; Baiker, A.

2009-01-01

available techniques, X-ray absorption spectroscopy (XAS) is a well-suited tool for this purpose as the different selected examples highlight. Two different techniques, scanning and full-field X-ray microscopy/tomography, are described and compared. At first, the tomographic structure of impregnated alumina...... pellets is presented using full-field transmission microtomography and compared to the results obtained with a scanning X-ray microbeam technique to analyse the catalyst bed inside a catalytic quartz glass reactor. On the other hand, by using XAS in scanning microtomography, the structure...... metal-based catalysts. In order to obtain spectroscopic information on the spatial variation of the oxidation state of the catalyst inside the reactor XAS spectra were recorded by scanning with a micro-focussed beam along the catalyst bed. Alternatively, full-field transmission imaging was used...

Challenges and Strategies in the Synthesis of Mesoporous Alumina Powders and Hierarchical Alumina Monoliths

Directory of Open Access Journals (Sweden)

Anne Galarneau

2012-02-01

Full Text Available A new rapid, very simple and one-step sol-gel strategy for the large-scale preparation of highly porous γ-Al2O3 is presented. The resulting mesoporous alumina materials feature high surface areas (400 m2 g−1, large pore volumes (0.8 mL g−1 and the ��-Al2O3 phase is obtained at low temperature (500 °C. The main advantages and drawbacks of different preparations of mesoporous alumina materials exhibiting high specific surface areas and large pore volumes such as surfactant-nanostructured alumina, sol-gel methods and hierarchically macro-/mesoporous alumina monoliths have been analyzed and compared. The most reproducible synthesis of mesoporous alumina are given. Evaporation-Induced Self-Assembly (EISA is the sole method to lead to nanostructured mesoporous alumina by direct templating, but it is a difficult method to scale-up. Alumina featuring macro- and mesoporosity in monolithic shape is a very promising material for in flow applications; an optimized synthesis is described.

Effect of hydrothermal process for inorganic alumina sol on crystal structure of alumina gel

Directory of Open Access Journals (Sweden)

K. Yamamura

2016-09-01

Full Text Available This paper reports the effect of a hydrothermal process for alumina sol on the crystal structure of alumina gel derived from hydrothermally treated alumina sol to help push forward the development of low temperature synthesis of α-Al2O3. White precipitate of aluminum hydroxide was prepared with a homogeneous precipitation method using aluminum nitrate and urea in aqueous solution. The obtained aluminum hydroxide precipitate was peptized by using acetic acid at room temperature, which resulted in the production of a transparent alumina sol. The alumina sol was treated with a hydrothermal process and transformed into an alumina gel film by drying at room temperature. Crystallization of the alumina gel to α-Al2O3 with 900 °C annealing was dominant for a hydrothermal temperature of 100 °C and a hydrothermal time of 60 min, as production of diaspore-like species was promoted with the hydrothermal temperature and time. Excess treatments with hydrothermal processes at higher hydrothermal temperature for longer hydrothermal time prevented the alumina gel from being crystallized to α-Al2O3 because the excess hydrothermal treatments promoted production of boehmite.

XPS analysis of supported catalysts prepared in water-in-oil microemulsion system

International Nuclear Information System (INIS)

Mohd Ambar Yarmo; Wong Hoi Jin; Tan Chew Khim; Anita Ramli; Shahidan Radiman

2002-01-01

Catalysts supported on γ-alumina prepared by water-in-oil microemulsion were studied by X-ray photoelectron spectroscopy for comparison with catalysts prepared by wet impregnation. Comparable shifts to higher binding energies indicated a metal-support interaction where metal obtained via microemulsion is very small in size and highly dispersed. The positive binding energy shifts could be explained from a net unit positive charge remaining on the cluster in the photoemission final state in addition to the metallic screening from a redistribution of states within the bands. (Author)

Kinetics of the reduction of uranium oxide catalysts

International Nuclear Information System (INIS)

Heynen, H.W.G.; Camp-van Berkel, M.M.; Bann, H.S. van der

1977-01-01

The reduction of uranium oxide and uranium oxide on alumina catalysts by ethylbenzene and by hydrogen has been studied in a thermobalance. Ethylbenzene mole fractions between 0.0026 and 0.052 and hydrogen mole fractions between 0.1 and 0.6 were applied at temperatures of 425--530 0 C. During the reduction the uranium oxides are converted into UO 2 . The rate of reduction of pure uranium oxide appears to be constant in the composition region UO/sub 2.6/-UO/sub 2.25/. The extent of this region is independent of the concentration of the reducing agents and of the reaction temperature. The constant rate is explained in terms of a constant oxygen pressure which is in equilibrium with the two solid phases, U 3 O/sub 8-x/ and U 4 O 9 . The reduction rate is first order in hydrogen and zero order in ethylbenzene with activation energies of 120 and 190 kJ mol -1 , respectively. Oxygen diffusion through the lattice is probably not rate limiting. The reduction behavior of uranium oxide on alumina is different from that of pure uranium oxide; the rate of reduction continuously decreases with increasing degree of reduction. An explanation for this behavior has been given by visualizing this catalyst as a set of isolated uranium oxide crystallites with a relative wide variation of diameters, in an alumina matrix. At the beginning of the reduction, carbon dioxide and water are the only reaction products. Thereafter, benzene is found as well and, finally, at U/O ratios below 2.25, styrene also appears in the reactor outlet

Steam reforming of ethanol over nickel-tungsten catalyst

Energy Technology Data Exchange (ETDEWEB)

Hernandez, I.P.; Fernandez, A.M. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco S/N, Temixco, Morelos (Mexico); Gochi-Ponce, Y. [Instituto Tecnologico de Oaxaca, Division de Estudios de Posgrado e Investigacion, Ave. Ing. Victor Bravo Ahuja, esq. Ave. Tecnologico No. 120, Col. Centro. Oaxaca, Oax (Mexico); Contreras Larios, J.L. [Universidad Autonoma Metropolitana Azcapotzalco, CBI., Energia, Av. Sn. Pablo 180, Col. Reynosa, C.P. 02200, Mexico D.F (Mexico)

2010-11-15

Ni-W/Al{sub 2}O{sub 3} catalysts were synthesized, characterized and tested for the steam reforming of ethanol from 300 to 600 C. Addition of Ni and W on the alumina, decreased the surface area and increased the pore volume of the mesoporous materials synthesized. The reaction products obtained were: H{sub 2}, CO{sub 2}, C{sub 2}H{sub 4}, CH{sub 4}, CO{sub 2}, CO and CH{sub 3}CHO. A promoting effect of Ni-W was observed in the conversion of ethanol to H{sub 2} from 15 to 30 wt.% Ni and 1 wt.% W. The selectivity to H{sub 2} on the alumina with Ni-W, was between 66.53 and 68.53% at 550 C, appearing some undesirable products, with low ratio of CO/CO{sub 2}. Reaction was studied on a fixed bed reactor at atmospheric pressure with an ethanol/water molar ratio of 1:4, from 300 to 600 C. The catalysts were characterized by the thermal gravimetric analysis (TGA)-Differential thermal analysis (DTA), N{sub 2} physisorption (BET and BJH methods), X-ray diffraction (XRD) and scanning electron microscopy (SEM), these techniques were used for characterization, before and after of the steam reforming. (author)

A small-angle neutron scattering investigation of coke deposits on catalysts

International Nuclear Information System (INIS)

Acharya, D.R.; Hughes, R.; Allen, A.J.

1990-01-01

Small-angle neutron scattering (SANS) has been used to characterize a silica-alumina catalyst before and after coke deposition. The reaction used to deactivate the catalyst was the isomerization of xylenes. The results showed that, while most of the surface area in this type of catalyst resides in the ultrafine pores of diameters less than 1 nm occupying about 7% of the sample volume, there appears to be no coke deposition in these pores. The coke seems to coat the solid structures of 3.3-nm diameter which are of capillary shape. Such structures occupy about 6% of the sample volume. The coke was found to correspond to amonolayer of composition CH 0.3 with a density of 1660 kg/m 3

alumina solid electrolyte

Indian Academy of Sciences (India)

-β/β -alumina ceramics come from two parent phases designated as β-alumina and β ..... Acknowledgements. This work was supported by the Energy Efficiency & ... of Trade, Industry & Energy, Republic of Korea (No. 20142010102460).

48 CFR 871.212 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 871.212... Rehabilitation and Employment Service 871.212 Contract clauses. Contracting officers must use the following clauses, as appropriate, in solicitations and contracts for vocational rehabilitation and employment...

48 CFR 239.7103 - Contract clauses.

Science.gov (United States)

2010-10-01

... OF DEFENSE SPECIAL CATEGORIES OF CONTRACTING ACQUISITION OF INFORMATION TECHNOLOGY Security and Privacy for Computer Systems 239.7103 Contract clauses. (a) Use the clause at 252.239-7000, Protection... requires protection against compromising emanations. (b) Use the clause at 252.239-7001, Information...

Screening, optimization and kinetics of Jatropha curcas oil transesterification with heterogeneous catalysts

Energy Technology Data Exchange (ETDEWEB)

Zanette, Andreia F.; Barella, Rodrigo A.; Silva, Edson A. [Department of Chemical Engineering, Universidade Estadual do Oeste do Parana, Toledo (Brazil); Pergher, Sibele B.C.; Treichel, Helen; Oliveira, Debora; Mazutti, Marcio A.; Oliveira, J. Vladimir [Department of Food Engineering, URI, Campus de Erechim, CEP 99700-000, Erechim (Brazil)

2011-02-15

This work investigates the production of fatty acid methyl esters (FAME) from Jatropha curcas oil using a variety of heterogeneous catalysts: resins, zeolites, clays, hydrotalcites, aluminas and niobium oxide. For this purpose, a catalyst screening was first conducted in a batch reactor at the following operating conditions: oil to methanol molar ratio of 1:9, 6 h of reaction, 5 wt% catalyst, at 333 and 393 K. From the screening step, KSF clay and Amberlyst 15 catalysts were selected to carry out a 2{sup 3} full factorial central composite rotatable design so as to elucidate the effects of process variables on FAME yield. The optimum reaction conditions for both catalysts were found to be oil to methanol molar ratio of 1:12, 5 wt% of catalyst, 433 K and 6 h of reaction with a FAME yield of about 70 wt%. A kinetic study was then experimentally performed and a semi-empirical model was built to represent the experimental data. Finally, catalyst re-utilization in five successive batch experiments was evaluated at the optimized conditions. (author)

Catalyst activity maintenance study for the liquid phase dimethyl ether process

Energy Technology Data Exchange (ETDEWEB)

Peng, X.D.; Toseland, B.A.; Underwood, R.P. [Air Products and Chemicals, Inc., Allentown, PA (United States)

1995-12-31

The co-production of dimethyl ether (DME) and methanol from syngas is a process of considerable commercial attractiveness. DME coproduction can double the productivity of a LPMEOH process when using coal-derived syngas. This in itself may offer chemical producers and power companies increased flexibility and more profitable operation. DME is also known as a clean burning liquid fuel; Amoco and Haldor-Topsoe have recently announced the use of DME as an alternative diesel fuel. Moreover, DME can be an interesting intermediate in the production of chemicals such as olefins and vinyl acetate. The current APCl liquid phase dimethyl ether (LPDME) process utilizes a physical mixture of a commercial methanol synthesis catalyst and a dehydration catalyst (e.g., {gamma}-alumina). While this arrangement provides a synergy that results in much higher syngas conversion per pass compared to the methanol-only process, the stability of the catalyst system suffers. The present project is aimed at reducing catalyst deactivation both by understanding the cause(s) of catalyst deactivation and by developing modified catalyst systems. This paper describes the current understanding of the deactivation mechanism.

Cold Spray Aluminum–Alumina Cermet Coatings: Effect of Alumina Content

Science.gov (United States)

Fernandez, Ruben; Jodoin, Bertrand

2018-04-01

Deposition behavior and deposition efficiency were investigated for several aluminum-alumina mixture compositions sprayed by cold spray. An increase in deposition efficiency was observed. Three theories postulated in the literature, explaining this increase in deposition efficiency, were investigated and assessed. Through finite element analysis, the interaction between a ceramic particle peening an impacting aluminum particle was found to be a possible mechanism to increase the deposition efficiency of the aluminum particle, but a probability analysis demonstrated that this peening event is too unlikely to contribute to the increment in deposition efficiency observed. The presence of asperities at the substrate and deposited layers was confirmed by a single-layer deposition efficiency measurement and proved to be a major mechanism in the increment of deposition efficiency of the studied mixtures. Finally, oxide removal produced by the impact of ceramic particles on substrate and deposited layers was evaluated as the complement of the other effects and found to also play a major role in increasing the deposition efficiency. It was found that the coatings retained approximately half of the feedstock powder alumina content. Hardness tests have shown a steady increase with the coating alumina content. Dry wear tests have revealed no improvement in wear resistance in samples with an alumina content lower than 22 wt.% compared to pure aluminum coatings. Adhesion strength showed a steady improvement with increasing alumina content in the feedstock powder from 18.5 MPa for pure aluminum coatings to values above 70 MPa for the ones sprayed with the highest feedstock powder alumina content.

48 CFR 1316.406 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 1316.406 Section 1316.406 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE CONTRACTING METHODS AND CONTRACT TYPES TYPES OF CONTRACTS Incentive Contracts 1316.406 Contract clauses. Insert a clause...

48 CFR 846.710 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 846.710 Section 846.710 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS CONTRACT MANAGEMENT QUALITY ASSURANCE Warranties 846.710 Contract clauses. The contracting officer shall insert the clause at...

48 CFR 819.709 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 819.709... PROGRAMS SMALL BUSINESS PROGRAMS The Small Business Subcontracting Program 819.709 Contract clause. The contracting officer shall insert VAAR clause 852.219-9, Small Business Subcontracting Plan Minimum...

48 CFR 935.071 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 935.071... CONTRACTING RESEARCH AND DEVELOPMENT CONTRACTING 935.071 Contract clause. The contracting officer must insert the clause at 952.235-71, Research Misconduct, in contracts, including management and operating...

Catalyst study for the decontamination of glove-box atmospheres containing tritium at MPC levels

International Nuclear Information System (INIS)

Chobot, J.; Montel, J.; Sannier, J.

1988-01-01

The BEATRICE loop was designed for studying the conversion of tritium at very low activity levels using catalytic oxidation followed by water trapping. The purpose is to study kinetic parameters required for the design of the NET tritium cleanup system with the two main objectives to operate without isotopic swamping and to determine the ability of efficient conversion at room temperature. From experiments carried out between 20 and 250 0 C it is concluded that two palladium/alumina and platinum/alumina catalysts are very efficient in removing tritium from contaminated gas mixtures down to a few MPC levels without isotopic swamping and even at room temperature. However at room temperature, in relation to tritium species trapped on the catalyst surface a progressive deactivation with time occurs. This phenomenon may be a concern for process efficiency and tritium inventory and regeneration conditions have to be determined in order to demonstrate industrial feasibility of operating at room temperature

Catalyst study for the decontamination of glove-boxe atmospheres containing tritium at MPC levels

International Nuclear Information System (INIS)

Chabot, J.; Montel, J.; Sannier, J.

1988-01-01

The BEATRICE loop was designed for studying the conversion of tritium at very low activity levels using catalytic oxidation followed by water trapping. The purpose is to study kinetic parameters required for the design of the NET tritium clean-up system with the two main objectives to operate without isotopic swamping and to determine the ability of efficient conversion at room temperature. From experiments carried out between 20 and 250 0 C it is concluded that two palladium/alumina and platinum/alumina catalysts are very efficient in removing tritium from contaminated gas mixtures down to a few MPC levels without isotopic swamping and even at room temperature. However at room temperature, in relation to tritium species trapped on the catalyst surface a progressive deactivation with time occurs. This phenomenon may be a concern for process efficiency and tritium inventory and best regeneration conditions have to be determined in order to demonstrate industrial feasibility of operating at room temperature

48 CFR 2439.107 - Contract clauses.

Science.gov (United States)

2010-10-01

... Departmental automated information systems or applications as they are defined in the clause. (b) The contracting officer shall insert the clause at 48 CFR 2452.239-71, Information Technology Virus Security, in... SPECIAL CATEGORIES OF CONTRACTING ACQUISITION OF INFORMATION TECHNOLOGY 2439.107 Contract clauses. (a) The...

48 CFR 46.710 - Contract clauses.

Science.gov (United States)

2010-10-01

... QUALITY ASSURANCE Warranties 46.710 Contract clauses. The clauses and alternates prescribed in this... research and development contract is contemplated and the use of a warranty clause has been approved under... performance specifications or design are of major importance; a fixed-price supply, service, or research and...

48 CFR 1842.271 - NASA clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true NASA clause. 1842.271 Section 1842.271 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION... NASA clause. Insert the clause at 1852.242-70, Technical Direction, when paragraph 3(m) of the NASA...

48 CFR 904.7201 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 904.7201... MATTERS Public Affairs 904.7201 Contract clause. The contracting officer shall insert the clause at 952.204-75, Public Affairs, in solicitations and contracts that require the contractor to release...

48 CFR 923.103 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 923.103... Contract clauses. Insert the clause at 952.223-78, Sustainable Acquisition Program, or its Alternate I, in all contracts under which the contractor operates Government-owned facilities or Government-owned...

48 CFR 837.403 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 837.403... OF CONTRACTING SERVICE CONTRACTING Nonpersonal Health Care Services 837.403 Contract clause. The contracting officer shall insert the clause at 852.237-7, Indemnification and medical liability insurance, in...

48 CFR 811.503 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 811.503... ACQUISITION PLANNING DESCRIBING AGENCY NEEDS Liquidated Damages 811.503 Contract clause. When the contracting... contracting officer must include the clause in 852.211-74, Liquidated damages, in the contract. ...

Effect of Different Catalyst Deposition Technique on Aligned Multiwalled Carbon Nanotubes Grown by Thermal Chemical Vapor Deposition

Directory of Open Access Journals (Sweden)

Mohamed Shuaib Mohamed Saheed

2014-01-01

Full Text Available The paper reported the investigation of the substrate preparation technique involving deposition of iron catalyst by electron beam evaporation and ferrocene vaporization in order to produce vertically aligned multiwalled carbon nanotubes array needed for fabrication of tailored devices. Prior to the growth at 700°C in ethylene, silicon dioxide coated silicon substrate was prepared by depositing alumina followed by iron using two different methods as described earlier. Characterization analysis revealed that aligned multiwalled carbon nanotubes array of 107.9 µm thickness grown by thermal chemical vapor deposition technique can only be achieved for the sample with iron deposited using ferrocene vaporization. The thick layer of partially oxidized iron film can prevent the deactivation of catalyst and thus is able to sustain the growth. It also increases the rate of permeation of the hydrocarbon gas into the catalyst particles and prevents agglomeration at the growth temperature. Combination of alumina-iron layer provides an efficient growth of high density multiwalled carbon nanotubes array with the steady growth rate of 3.6 µm per minute for the first 12 minutes and dropped by half after 40 minutes. Thicker and uniform iron catalyst film obtained from ferrocene vaporization is attributed to the multidirectional deposition of particles in the gaseous form.

Al2O3-Cact-(CuO, Cr2O3, Co3O4 Adsorbents-Catalysts: Preparation and Characterization

Directory of Open Access Journals (Sweden)

Gitana DABRILAITĖ-KUDŽMIENĖ

2013-03-01

Full Text Available Al2O3-Cact-(CuO, Cr2O3 Co3O4 adsorbents-catalysts were prepared using Al2O3-Cact (alumina gel–activated carbon adsorbent and different amount of CuO, Cr2O3 and Co3O4. The active components were incorporated into wet alumina gel–carbon mixture using different conditions (by sol-gel method and mixing a milled metal oxides. Equilibrium adsorptive capacity measurements of alcohol vapours were carried out in order to determine the influence of preparation conditions on the stability of prepared adsorbents–catalysts. Specific surface area of the prepared adsorbents-catalysts were measured by BET method. It was established that for adsorbent-catalyst produced by sol-gel method SBET = 244.7 m2/g. Surface area SBET = 29.32 m2/g was obtained for adsorbent-catalyst with metal oxides. On the basis of these results it was assumed that active carbon was lost in this adsorbent-catalyst during the preparation process. Sol-gel derived adsorbent–catalyst was tested for the oxidation of methanol vapours. Catalytic oxidation was carried out in fixed-bed reactor. Experimental data indicate that adsorptive capacity of the adsorbent–catalyst is (3.232 – 3.259 mg/m3 CH3OH at relative air humidity is 40 % – 50 %. During a fast heating of CH3OH – saturated adsorbent-catalyst a part of adsorbate is converted to CO2 and H2O. Methanol conversion increases with increasing of adsorbent-catalyst heating rate.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3832

48 CFR 803.7001 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 803.7001... Practices 803.7001 Contract clause. The contracting officer shall insert the clause at 852.203-71, Display of Department of Veterans Affairs Hotline poster, in solicitations and contracts expected to equal or...

48 CFR 819.7009 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 819.7009... Acquisition Program 819.7009 Contract clauses. The contracting officer shall insert VAAR clause 852.219-10... Veteran-Owned Small Business Set-Aside in solicitations and contracts for acquisitions under this subpart. ...

48 CFR 903.971 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 903.971... Contract clause. The contracting officer shall insert the clause at 952.203-70, Whistleblower Protection for Contractor Employees, in contracts that involve work to be done on behalf of DOE directly related...

48 CFR 926.7104 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 926.7104... 1993. 926.7104 Contract clause. The contracting officer shall insert the clause at 48 CFR (DEAR) 952.226-74, Displaced Employee Hiring Preference, in contracts (except for contracts for commercial items...

48 CFR 822.305 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 822.305... PROGRAMS APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Contract Work Hours and Safety Standards Act 822.305 Contract clause. The contracting officer shall insert the clause at 852.222-70, Contract Work...

48 CFR 923.7003 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 923.7003... Efficiency, Renewable Energy Technologies, and Occupational Safety Programs 923.7003 Contract clauses. (a) A decision to include or not include environmental, safety and health clauses in DOE contracts shall be made...

48 CFR 53.111 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Contract clause. 53.111... AND FORMS FORMS General 53.111 Contract clause. Contracting officers shall insert the clause at 52.253-1, Computer Generated Forms, in solicitations and contracts that require the contractor to submit...

48 CFR 925.7004 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 925.7004... FOREIGN ACQUISITION Acquisition of Nuclear Hot Cell Services 925.7004 Contract clause. The contracting... solicitations and contracts involving nuclear hot cell services. This clause does not flow down to second-tier...

48 CFR 251.205 - Contract clause.

Science.gov (United States)

2010-10-01

... Fleet Management System (IFMS) Vehicles 251.205 Contract clause. Use the clause at 252.251-7001, Use of Interagency Fleet Management System (IFMS)Vehicles and Related Services, in solicitations and contracts which include the clause at FAR 52.251-2, Interagency Fleet Management System (IFMS) Vehicles and Related...

48 CFR 203.1004 - Contract clauses.

Science.gov (United States)

2010-10-01

... OF DEFENSE GENERAL IMPROPER BUSINESS PRACTICES AND PERSONAL CONFLICTS OF INTEREST Contractor Code of Business Ethics and Conduct 203.1004 Contract clauses. (a) Use the clause at 252.203-7003 in solicitations and contracts that include the FAR clause 52.203-13, Contractor Code of Business Ethics and Conduct...

Effect of Rh-based additives on NO and CO formed during regeneration of spent FCC catalyst

Energy Technology Data Exchange (ETDEWEB)

Iliopoulou, E.F.; Efthimiadis, E.A.; Vasalos, I.A. [Aristotle University of Thessaloniki and Center for Research and Technology Hellas, Chemical Process Engineering Research Institute, Department of Chemical Engineering, P.O. Box 1517, 54006 University City, Thessaloniki (Greece); Barth, J.-O.; Lercher, J.A. [Institut fur Technische Chemie, Technische Universitat Munchen, Lichtenbergstrasse 4, D-85748 Garching (Germany)

2004-02-10

Regeneration studies of spent FCC catalyst were performed in a bench-scale unit under reaction conditions that sufficiently simulate those in the regenerator of the fluid catalytic cracking (FCC) unit. The effect of a conventional Pt-based CO promoter (CP-3) on the composition of flue gases was examined. As expected addition of CP-3 in the catalytic inventory decreased CO emissions by one order of magnitude, but tripled the NO emissions independently of the concentration of CO promoter used. Addition of a series of Rh-based catalysts modified the composition of flue gases emitted during regeneration. The parameters under study were the catalytic support, the Rh loading on the additive, and the amount of additive used during regeneration. Both a stoichiometric spinel MgO{center_dot}Al{sub 2}O{sub 3} of high crystallinity and a commercial alumina were competent supports. Promotion of the alumina support with Ce or performing regeneration introducing CO did not affect the additive performance significantly. A combined performance of CO oxidation and NO reduction was achieved minimizing both the Rh loading in the additive (0.1wt.%) and the concentration of additive used during regeneration (1wt.%). IR studies suggest that NO reduction by CO over Rh/alumina additives proceeds via the dissociative adsorption of NO, the formation of NCO species on Rh and their migration to the alumina support to finally yield N{sub 2} and CO{sub 2}.

Formation of nitrogen compounds from nitrogen-containing rings during oxidative regeneration of spent hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.; Nielsen, M.; Jurasek, P. [CANMET, Ottawa, ON (Canada). Energy Research Laboratories

1995-05-01

Commercial CoMo and NiMo catalysts in an oxidic and sulfided form and a {gamma}-alumina were deposited with pyrrole, pyridine, and quinoline. The deposited catalysts and two spent hydroprocessing catalysts were pyrolyzed and oxidized under conditions typical of regeneration of hydroprocessing catalysts. The formation of NH{sub 3} and HCN, as well as selected cases of N{sub 2}O and NO, was monitored during the experiments. NH{sub 3} and HCN were formed during pyrolysis of pyrrole-deposited catalysts whereas only NH{sub 3} was formed during that of pyridine-and quinoline-deposited catalysts. For all deposited catalysts, both NH{sub 3} and HCN were formed during temperature programmed oxidation in 2% O{sub 2}. For spent catalysts, a small amount of N{sub 2}O was formed in 2 and 4% O{sub 2}. For pyrrole-deposited catalysts, large yields of N{sub 2}O were formed in 4% O{sub 2}. Under the same conditions, N{sub 2}O yields for pyridine- and quinoline-deposited catalysts were very small. 13 refs., 12 figs., 6 tabs.

24 CFR 221.1 - Savings clause.

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Savings clause. 221.1 Section 221.1... MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT AND OTHER AUTHORITIES LOW COST AND MODERATE INCOME MORTGAGE INSURANCE-SAVINGS CLAUSE Eligibility Requirements-Low Cost Homes-Savings Clause § 221.1...

H3PO4/Al2O3 catalysts: characterization and catalytic evaluation of oleic acid conversion to biofuels and biolubricant

Directory of Open Access Journals (Sweden)

Lucia Regina Raddi de Araujo

2006-06-01

Full Text Available Al2O3 and H3PO4/Al2O3 catalysts were investigated in the conversion of oleic acid to biofuels and biolubricant at 1 atm and at 623 K. The catalytic tests were performed in a fixed bed and continuous flow reactor, using an oleic acid-catalyst ratio of 4 and N2 as the carrier gas. The reaction products were analyzed by gas chromatography and acidity measurements. N2 adsorption-desorption, X ray diffraction, 31P nuclear magnetic resonance and FT-IR spectroscopy were also employed to evaluate the textural, structural and acidic properties of the catalysts. The results showed that phosphoric acid impregnation improved the alumina decarboxylation activities, generating hydrocarbons in the range of gasoline, diesel oil and lubricant oil. The best catalytic performance was achieved with the highest surface area alumina impregnated with H3PO4, which was the solid that allied high total acidity with a large quantity of mesopores.

A comparative parametric study of a catalytic plate methane reformer coated with segmented and continuous layers of combustion catalyst for hydrogen production

Science.gov (United States)

Mundhwa, Mayur; Parmar, Rajesh D.; Thurgood, Christopher P.

2017-03-01

A parametric comparison study is carried out between segmented and conventional continuous layer configurations of the coated combustion-catalyst to investigate their influence on the performance of methane steam reforming (MSR) for hydrogen production in a catalytic plate reactor (CPR). MSR is simulated on one side of a thin plate over a continuous layer of nickel-alumina catalyst by implementing an experimentally validated surface microkinetic model. Required thermal energy for the MSR reaction is supplied by simulating catalytic methane combustion (CMC) on the opposite side of the plate over segmented and continuous layer of a platinum-alumina catalyst by implementing power law rate model. The simulation results of both coating configurations of the combustion-catalyst are compared using the following parameters: (1) co-flow and counter-flow modes between CMC and MSR, (2) gas hourly space velocity and (3) reforming-catalyst thickness. The study explains why CPR designed with the segmented combustion-catalyst and co-flow mode shows superior performance not only in terms of high hydrogen production but also in terms of minimizing the maximum reactor plate temperature and thermal hot-spots. The study shows that the segmented coating requires 7% to 8% less combustion-side feed flow and 70% less combustion-catalyst to produce the required flow of hydrogen (29.80 mol/h) on the reforming-side to feed a 1 kW fuel-cell compared to the conventional continuous coating of the combustion-catalyst.

Selective low temperature NH3 oxidation to N2 on copper-based catalysts

NARCIS (Netherlands)

Gang, L.; Grondelle, van J.; Anderson, B.G.; Santen, van R.A.

1999-01-01

TPD, TPR, UV-visible spectroscopy, and high-resolution electron microscopy (HREM) have been used to characterize the state and reactivity of alumina-supported copper-based catalysts for the oxidation of ammonia to nitrogen. The results of HREM and UV spectra show that a CuAl2O4-like phase is more

Treatment of spent catalyst from the nitrogenous fertilizer industry-A review of the available methods of regeneration, recovery and disposal

International Nuclear Information System (INIS)

Singh, Bina

2009-01-01

Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste. The recovery of metals from these catalysts is an important economic aspect as most of these catalysts are supported, usually on alumina/silica with varying percent of metal; metal concentration could vary from 2.5 to 20%. Metals like Ni, Mo, Co, Rh, Pt, Pd, etc., are widely used as a catalyst in chemical and petrochemical industries and fertilizer industries. They are generally supported on porous materials like alumina and silica through precipitation or impregnation processes. Many workers have adapted pyrometallurgy and Hydrometallurgy process for recovery of precious metals. Many workers have studied the recovery of nickel from a spent catalyst in an ammonia plant by leaching it in sulphuric acid solution (Hydrometallurgy). Ninety-nine percent of the nickel was recovered as nickel sulphate when the catalyst, having a particle size of 0.09 mm was dissolved in an 80% sulphuric acid solution for 50 min in at 70 deg. C. Many researcher have studied the extraction of metals from spent catalyst by roasting-extraction method (Pyrometallurgy). Chelating agents are the most effective extractants, which can be introduced in the soil washing fluid to enhance heavy metal extraction from contaminated soils. The advantages of chelating agents in soil cleanup include high efficiency of metal extraction, high thermodynamic stabilities of the metal complexes formed, good solubilities of the metal complexes, and low adsorption of the chelating agents on soils, But very few workers have attempted chelating agent to extract metals from spent catalyst.

48 CFR 3.1004 - Contract clauses.

Science.gov (United States)

2010-10-01

... applicable posters; and (ii) Insert the website link(s) or other contact information for obtaining the agency... Contract clauses. (a) Insert the clause at FAR 52.203-13, Contractor Code of Business Ethics and Conduct... or will be performed entirely outside the United States, insert the clause at FAR 52.203-14, Display...

Insights into the deactivation mechanism of supported tungsten hydride on alumina (W-H/Al2O3) catalyst for the direct conversion of ethylene to propylene

KAUST Repository

Mazoyer, Etienne

2014-04-01

Tungsten hydride supported on alumina prepared by the surface organometallic chemistry method is an active precursor for the direct conversion of ethylene to propylene at low temperature and pressure. An extensive contact time study revealed that the dimerization of ethylene to 1-butene is the primary and also the rate limiting step. The catalytic cycle further involves isomerization of 1-butene to 2-butene, followed by cross-metathesis of ethylene and 2-butene to yield propylene with high selectivity. The deactivation mechanism of this reaction has been investigated. The used catalyst was extensively examined by DRIFTS, solid-state NMR, EPR, UV-Vis, TGA and DSC techniques. It was found that a large amount of carbonaceous species, which were due to side reaction like olefin polymerization took place with time on stream, significantly hindering the dimerization of ethylene to 1-butene and therefore the production of propylene. Crown Copyright © 2014 Published by Elsevier B.V. All rights reserved.

Correlation between Fischer-Tropsch catalytic activity and composition of catalysts

Directory of Open Access Journals (Sweden)

Subbarao Duvvuri

2011-11-01

Full Text Available Abstract This paper presents the synthesis and characterization of monometallic and bimetallic cobalt and iron nanoparticles supported on alumina. The catalysts were prepared by a wet impregnation method. Samples were characterized using temperature-programmed reduction (TPR, temperature-programmed oxidation (TPO, CO-chemisorption, transmission electron microscopy (TEM, field emission scanning electron microscopy (FESEM-EDX and N2-adsorption analysis. Fischer-Tropsch synthesis (FTS was carried out in a fixed-bed microreactor at 543 K and 1 atm, with H2/CO = 2 v/v and space velocity, SV = 12L/g.h. The physicochemical properties and the FTS activity of the bimetallic catalysts were analyzed and compared with those of monometallic cobalt and iron catalysts at similar operating conditions. H2-TPR analysis of cobalt catalyst indicated three temperature regions at 506°C (low, 650°C (medium and 731°C (high. The incorporation of iron up to 30% into cobalt catalysts increased the reduction, CO chemisorption and number of cobalt active sites of the catalyst while an opposite trend was observed for the iron-riched bimetallic catalysts. The CO conversion was 6.3% and 4.6%, over the monometallic cobalt and iron catalysts, respectively. Bimetallic catalysts enhanced the CO conversion. Amongst the catalysts studied, bimetallic catalyst with the composition of 70Co30Fe showed the highest CO conversion (8.1% while exhibiting the same product selectivity as that of monometallic Co catalyst. Monometallic iron catalyst showed the lowest selectivity for C5+ hydrocarbons (1.6%.

48 CFR 970.3270 - Standard financial management clauses.

Science.gov (United States)

2010-10-01

... Standard financial management clauses. (a) The following DEAR and FAR clauses are standard financial... Accounting Standards. (b) The following DEAR clauses are standard financial management clauses. The... systems: (1) 970.5232-7, Financial management system. (2) 970.5232-8, Integrated accounting. (c) Any...

Large-scale synthesis of coiled-like shaped carbon nanotubes using bi-metal catalyst

Science.gov (United States)

Krishna, Vemula Mohana; Somanathan, T.; Manikandan, E.; Umar, Ahmad; Maaza, M.

2018-02-01

Carbon nanomaterials (CNMs), especially carbon nanotubes (CNTs) with coiled structure exhibit scientifically fascinating. They may be projected as an innovative preference to future technological materials. Coiled carbon nanotubes (c-CNTs) on a large-scale were successfully synthesized with the help of bi-metal substituted α-alumina nanoparticles catalyst via chemical vapor deposition (CVD) technique. Highly spring-like carbon nanostructures were observed by field emission scanning electron microscope (FESEM) examination. Furthermore, the obtained material has high purity, which correlates the X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) analysis. Raman spectroscopy reveals that the carbon multi layers are well graphitized and crystalline, even if they have defects in its structure due to coiled morphology. High-resolution transmission electron microscope (HRTEM) describes internal structure and dia of the product. Ultimately, results support the activity of bi-metal impregnated α-alumina nanoparticles catalyst to determine the high yield, graphitization and internal structure of the material. We have also studied the purified c-CNTs magnetic properties at room temperature and will be an added advantage in several applications.

Benign and efficient preparation of thioethers by solvent-free S-alkylation of thiols with alkyl halides catalyzed by potassium fluoride on alumina

DEFF Research Database (Denmark)

Nguyen, Kha Ngoc; Duus, Fritz; Luu, Thi Xuan Thi

2016-01-01

The preparation of thioethers by S-alkylation of various thiols with alkyl halides under solvent-free reaction conditions using potassium fluoride on alumina (KF/Al2O3) as a solid catalyst has been investigated in detail with respect to three different modes of reaction activation (ultrasound...... irradiation, microwave irradiation, and conventional heating) for obtaining maximum yield of the thioether. The importance of KF/Al2O3 as a particularly efficient catalyst was corroborated for all three modes of reaction activation, although the reaction time was found to be strongly dependent on the mode...

Bimetallic catalysts for continuous catalytic wet air oxidation of phenol.

Science.gov (United States)

Fortuny, A; Bengoa, C; Font, J; Fabregat, A

1999-01-29

Catalytic wet oxidation has proved to be effective at eliminating hazardous organic compounds, such as phenol, from waste waters. However, the lack of active long-life oxidation catalysts which can perform in aqueous phase is its main drawback. This study explores the ability of bimetallic supported catalysts to oxidize aqueous phenol solutions using air as oxidant. Combinations of 2% of CoO, Fe2O3, MnO or ZnO with 10% CuO were supported on gamma-alumina by pore filling, calcined and later tested. The oxidation was carried out in a packed bed reactor operating in trickle flow regime at 140 degrees C and 900 kPa of oxygen partial pressure. Lifetime tests were conducted for 8 days. The pH of the feed solution was also varied. The results show that all the catalysts tested undergo severe deactivation during the first 2 days of operation. Later, the catalysts present steady activity until the end of the test. The highest residual phenol conversion was obtained for the ZnO-CuO, which was significantly higher than that obtained with the 10% CuO catalyst used as reference. The catalyst deactivation is related to the dissolution of the metal oxides from the catalyst surface due to the acidic reaction conditions. Generally, the performance of the catalysts was better when the pH of the feed solution was increased.

Research Update: Nickel filling in nanofeatures using supercritical fluid and its application to fabricating a novel catalyst structure for continuous growth of nanocarbon fibers

Directory of Open Access Journals (Sweden)

Mitsuhiro Watanabe

2014-10-01

Full Text Available A novel catalyst structure for continuous growth of nanocarbon fibers is proposed. In this structure, catalyst nanofibers are embedded in a membrane that separates the growth ambient into carbon-supplying and carbon-precipitating environments. The catalyst nanofibers pierce through the membrane so that carbon source gas is supplied only to one end of the catalyst fibers and nanocarbon fibers grow continuously at the other end. To realize this structure, self-supporting anodized alumina was used as a membrane, and its nano-through-holes were filled with catalyst Ni in supercritical CO2 fluid. Direct carbon growth from the Ni nanofibers was confirmed using this catalyst structure.

48 CFR 2009.570-5 - Contract clauses.

Science.gov (United States)

2010-10-01

... COMPETITION AND ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS Organizational Conflicts of Interest 2009.570-5 Contract clauses. (a) General contract clause. All contracts and simplified acquisitions of the types set forth in 2009.570-4(b) must include the clause entitled, “Contractor Organizational Conflicts of...

Model studies of secondary hydrogenation in Fischer-Tropsch synthesis studied by cobalt catalysts

Energy Technology Data Exchange (ETDEWEB)

Aaserud, Christian

2003-07-01

of propene hydrogenation (g/g{sub Co(surface)}, h) increased with increasing surface area of the alumina support. Promoting the cobalt catalyst with rhenium increased the cobalt dispersion, but it did not affect the rate of propene hydrogenation. CO hydrogenation on the same alumina supported catalysts at FT conditions (210 {sup o}C, 20 bar and H{sub 2}/CO = 2.1) has shown that the C{sub 5+} selectivity increased with decreasing surface area of the alumina support. Decreased importance of hydrogenation of olefins will result in increased selectivity of C{sub 5+} due to increased probability for readsorption and further chain growth of olefins. Decreased propene hydrogenation on catalysts with low surface area fits very well with increased C{sub 5+} selectivity in FT synthesis for these catalysts. The effect of water on the activity for propene hydrogenation on the same catalysts as used for the propene hydrogenation study has also been studied in a fixed bed microreactor at 120 {sup o}C, 1.8 bar, H{sub 2}/C{sub 3}H{sub 6} = 6 and H{sub 2}O/H{sub 2} = 0.8. Cobalt FT catalysts on various alumina supports, on silica support, on titania support and also unsupported cobalt catalysts were all decreasing their activity for propene hydrogenation sharply when water was added to the feed. Inhibition of propene hydrogenation during water addition was reversible for all catalysts. Reversibility of the propene hydrogenation activity indicates that no deactivation of the catalyst occurred during water addition. It is suggested that the decreased activity of propene hydrogenation during water addition is due to competitive adsorption of water on the cobalt surface. Decreased importance of secondary hydrogenation of olefins will result in an improved selectivity of C{sub 5} and higher hydrocarbons. By adding water during FT synthesis it has been observed that the C{sub 5+} selectivity increased. Improved C{sub 5+} selectivity is therefore in line with the observed inhibition of

Surface science models of CoMoS hydrodesulfurisation catalysts

Energy Technology Data Exchange (ETDEWEB)

De Jong, A.M.; De Beer, V.H.J.; Van Veen, J.A.R.; Niemantsverdriet, J.W. [Schuit Institute of Catalysis, Eindhoven University of Technology, Eindhoven (Netherlands)

1997-07-01

Characterization of supported catalysts with surface spectroscopic techniques is often limited due to restraints imposed by the support material. The use of flat conducting substrates as a model support offers a way to apply these techniques to their full potential. Such surface science models of silica and alumina supported CoMoS catalysts have been made by impregnating thin SiO{sub 2} and Al{sub 2}O{sub 3} films with a solution of nitrilotriacetic acid (NTA) complexes of cobalt and molybdenum. X-ray Photoelectron Spectroscopy (XPS) spectra indicate that the order in which cobalt and molybdenum transfer to the sulfided state is reversed with respect to oxidic Co and Mo systems prepared by conventional methods, implying that NTA complexation retards the sulfidation of cobalt to temperatures where MoS{sub 2} is already formed. Catalytic tests show that the CoMoS model catalysts exhibit activities for thiophene desulfurisation and product distributions similar to those of their high surface area counterparts. 25 refs.

Effect of Ce on performance and physicochemical properties of Pt-containing automotive emission control catalysts

International Nuclear Information System (INIS)

Nunan, J.G.; Silver, R.G.; Bradley, S.A.

1992-01-01

Present-day automotive emission control catalysts contain noble metals such as Pt, Pd and Rh all on an alumina support with a variety of promoters. Ce is one of the most important promoters. In this paper, the interaction between Pt and Ce is studied using TPR and STEM on a variety of catalysts. The degree of Pt/Ce interaction is increased by decreasing CeO 2 crystallite size, and to a lesser extent by increasing CeO 2 loading. Direct Pt/Ce interaction leads to a synergistic reduction of both Pt and surface Ce. This reduction qualitatively correlates with catalyst performance after activation in a reducing gas. It is proposed that this synergistic reduction of Pt and Ce is associated with observed improvements in catalyst performance using a non-oscillating exhaust gas

48 CFR 970.0470-2 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.0470... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Administrative Matters 970.0470-2 Contract clause. The contracting officer shall insert the clause at 970.5204-2, Laws, Regulations, and DOE...

48 CFR 970.0371-9 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.0371... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Improper Business Practices and Personal Conflicts of Interest 970.0371-9 Contract clause. The contracting officer shall insert the clause at 970...

48 CFR 970.1103-4 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.1103... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Describing Agency Needs 970.1103-4 Contract clause. Insert the clause at 48 CFR 52.211-5, Material Requirements, in solicitations and contracts. ...

48 CFR 970.0370-2 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.0370... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Improper Business Practices and Personal Conflicts of Interest 970.0370-2 Contract clause. (a) The contracting officer shall insert the clause at 970...

Alumina ceramics prepared with new pore-forming agents

Directory of Open Access Journals (Sweden)

Zuzana Živcová

2008-06-01

Full Text Available Porous ceramics have a wide range of applications at all length scales, ranging from fi ltration membranes and catalyst supports to biomaterials (scaffolds for bone ingrowths and thermally or acoustically insulating bulk materials or coating layers. Organic pore-forming agents (PFAs of biological origin can be used to control porosity, pore size and pore shape. This work concerns the characterization and testing of several less common pore-forming agents (lycopodium, coffee, fl our and semolina, poppy seed, which are of potential interest from the viewpoint of size, shape or availability. The performance of these new PFAs is compared to that of starch, which has become a rather popular PFA for ceramics during the last decade. The PFAs investigated in this work are in the size range from 5 μm (rice starch to approximately 1 mm (poppy seed, all with more or less isometric shape. The burnout behavior of PFAs is studied by thermal analysis, i.e. thermogravimetry and differential thermal analysis. For the preparation of porous alumina ceramics from alumina suspensions containing PFAs traditional slip casting (into plaster molds and starch consolidation casting (using metal molds are used in this work. The resulting microstructures are investigated using optical microscopy, combined with image analysis, as well as other methods (Archimedes method of double-weighing in water, mercury intrusion porosimetry.

Preparation and Characterization of NiMo/Al2O3Catalyst for Hydrocracking Processing

Directory of Open Access Journals (Sweden)

Widiyadi Aditya

2018-01-01

Full Text Available Hydrocracking is a chemical process used in petroleum refineries for converting high boiling hydrocarbons in petroleum crude oils to more valuable lower boiling products such as gasoline, kerosene, and diesel oil that operate at high temperature and pressure. Catalyst was used in hydrocracking to reduce temperature and pressure. Hydrocracking catalyst are composed of active components and support. Alumina is widely used in hydrocracking process as catalyst support due to its high surface area, high thermal stability, and low prices. The objective of this research was preparated NiMo/Al2O3 catalyst that used as hydrocracking catalyst. Catalyst was synthesized by wetness impregnation method and simple heating method with various kind of Al2O3. The physicochemical properties of catalyst were investigated by X-ray diffraction (XRD to determine type of crystal and scanning electron microscopy (SEM to determine morphology of the catalyst. The NiMo/Al2O3 catalyst prepared by aluminium potassium sulfate dodecahydrate exhibited the highest crystallinity of 90.23% and it is clear that MoO3 and NiO crystallites are highly dispersed on the NiMo/Al2O3 catalyst which indicates as the best catalyst. The catalytic activity in hydrocracking process was successfully examined to convert fatty acid into hydrocarbon.

Preparation and Characterization of NiMo/Al2O3Catalyst for Hydrocracking Processing

Science.gov (United States)

Widiyadi, Aditya; Guspiani, Gema Adil; Riady, Jeffry; Andreanto, Rikky; Chaiunnisa, Safina Dea; Widayat

2018-02-01

Hydrocracking is a chemical process used in petroleum refineries for converting high boiling hydrocarbons in petroleum crude oils to more valuable lower boiling products such as gasoline, kerosene, and diesel oil that operate at high temperature and pressure. Catalyst was used in hydrocracking to reduce temperature and pressure. Hydrocracking catalyst are composed of active components and support. Alumina is widely used in hydrocracking process as catalyst support due to its high surface area, high thermal stability, and low prices. The objective of this research was preparated NiMo/Al2O3 catalyst that used as hydrocracking catalyst. Catalyst was synthesized by wetness impregnation method and simple heating method with various kind of Al2O3. The physicochemical properties of catalyst were investigated by X-ray diffraction (XRD) to determine type of crystal and scanning electron microscopy (SEM) to determine morphology of the catalyst. The NiMo/Al2O3 catalyst prepared by aluminium potassium sulfate dodecahydrate exhibited the highest crystallinity of 90.23% and it is clear that MoO3 and NiO crystallites are highly dispersed on the NiMo/Al2O3 catalyst which indicates as the best catalyst. The catalytic activity in hydrocracking process was successfully examined to convert fatty acid into hydrocarbon.

Kinetic Parameters of Non-Isothermal Thermogravimetric Non-Catalytic and Catalytic Pyrolysis of Empty Fruit Bunch with Alumina by Kissinger and Ozawa Methods

Science.gov (United States)

Rahayu Mohamed, Alina; Li, Nurfahani; Sohaimi, Khairunissa Syairah Ahmad; Izzati Iberahim, Nur; Munirah Rohaizad, Nor; Hamzah, Rosniza

2018-03-01

The non-isothermal thermogravimetric non-catalytic and catalytic empty fruit bunch (EFB) pyrolysis with alumina were performed at different heating rates of 10, 15, 20, 25, 30 and 40 K/min under nitrogen atmosphere at a flow rate of 100 ml/min under dynamic conditions from 301 K to 1273 K. The activation energy were calculated based on Kissinger and Ozawa methods. Both reactions followed first order reactions. By Kissinger method, the activation energy and Ln A values for non-catalytic and catalytic EFB pyrolysis with alumina were 188.69 kJ mol-1 and 201.67 kJ/mol respectively. By Ozawa method, the activation energy values for non-catalytic and catalytic EFB pyrolysis with alumina were 189.13 kJ/mol and 201.44 kJ/mol respectively. The presence of catalyst increased the activation energy values for EFB pyrolysis as calculated by Kissinger and Ozawa methods.

48 CFR 27.201-2 - Contract clauses.

Science.gov (United States)

2010-10-01

... the patent indemnity clause. Exclusion from indemnity of identified patents, as distinguished from... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Contract clauses. 27.201-2... REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS Patents and Copyrights 27.201-2 Contract clauses. (a)(1) Insert the...

48 CFR 909.507-2 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 909.507-2... PLANNING CONTRACTOR QUALIFICATIONS Organizational and Consultant Conflicts of Interest 909.507-2 Contract clause. (a)(1) The contracting officer shall insert the clause at 952.209-72, Organizational Conflicts of...

48 CFR 970.0808-3 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.0808... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Required sources of supplies and services 970.0808-3 Contract clause. The contracting officer shall insert the clause at 970.5208-1, Printing, in all...

48 CFR 942.270-2 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 942.270-2 Section 942.270-2 Federal Acquisition Regulations System DEPARTMENT OF ENERGY CONTRACT MANAGEMENT CONTRACT ADMINISTRATION AND AUDIT SERVICES Contract Administration Services 942.270-2 Contract clause. The clause at 952...

48 CFR 1603.7003 - Contract clause.

Science.gov (United States)

2010-10-01

... HEALTH BENEFITS ACQUISITION REGULATION GENERAL IMPROPER BUSINESS PRACTICES AND PERSONAL CONFLICTS OF INTEREST Misleading, Deceptive, or Unfair Advertising 1603.7003 Contract clause. The clause at 1652.203-70...

Benzene destruction in claus process by sulfur dioxide: A reaction kinetics study

KAUST Repository

Sinha, Sourab

2014-07-02

Benzene, toluene and xylene (BTX) are present as contaminants in the H 2S gas stream entering a Claus furnace. The exhaust gases from the furnace enter catalytic units, where BTX form soot particles. These particles clog and deactivate the catalysts. A solution to this problem is BTX oxidation before the gases enter catalyst beds. This work presents a theoretical investigation on benzene oxidation by SO2. Density functional theory is used to develop a detailed mechanism for phenyl radical -SO2 interactions. The mechanism begins with SO2 addition to phenyl radical after overcoming an energy barrier of 6.4 kJ/mol. This addition reaction is highly exothermic, where a reaction energy of 182 kJ/mol is released. The most favorable pathway involves O-S bond breakage, leading to the release of SO. A remarkable similarity between the pathways for phenyl radical oxidation by O2 and its oxidation by SO2 is observed. The reaction rate constants are also evaluated to facilitate process simulations. © 2014 American Chemical Society.

The Conditional Clause in Igbo | Okoro | Lagos Notes and Records

African Journals Online (AJOL)

Structurally, the conditional clause can occur before or after the main clause, dropping or taking on a variety of subordinating conjunctions, the commonest of which is (mà) ọ bụrụ na; it is also possible to state only the conditional clause without the main clause, or the main clause without the conditional clause, with the ...

48 CFR 229.402-70 - Additional clauses.

Science.gov (United States)

2010-10-01

... performance will be in Spain. (f) Use the clause at 252.229-7006, Value Added Tax Exclusion (United Kingdom.... (i) Use the clause at 252.229-7009, Relief from Customs Duty and Value Added Tax on Fuel (Passenger... SYSTEM, DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS TAXES Contract Clauses 229.402-70...

48 CFR 970.1706-2 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.1706... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Special Contracting Methods 970.1706-2 Contract clause. The contracting officer shall insert the clause at 48 CFR 52.217-9, Option to Extend the Term of...

48 CFR 709.507-2 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 709.507-2... PLANNING CONTRACTOR QUALIFICATIONS Organizational Conflicts of Interest 709.507-2 Contract clause. (a)-(b... after award of a contract, the clause found at 752.209-71 shall be inserted in all contracts whenever...

48 CFR 970.1707-4 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.1707... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Special Contracting Methods 970.1707-4 Contract clause. Insert the clause at 970.5217-1, Work for Others Program (Non-DOE Funded Work), in any contract...

Bauxite Mining and Alumina Refining

Science.gov (United States)

Frisch, Neale; Olney, David

2014-01-01

Objective: To describe bauxite mining and alumina refining processes and to outline the relevant physical, chemical, biological, ergonomic, and psychosocial health risks. Methods: Review article. Results: The most important risks relate to noise, ergonomics, trauma, and caustic soda splashes of the skin/eyes. Other risks of note relate to fatigue, heat, and solar ultraviolet and for some operations tropical diseases, venomous/dangerous animals, and remote locations. Exposures to bauxite dust, alumina dust, and caustic mist in contemporary best-practice bauxite mining and alumina refining operations have not been demonstrated to be associated with clinically significant decrements in lung function. Exposures to bauxite dust and alumina dust at such operations are also not associated with the incidence of cancer. Conclusions: A range of occupational health risks in bauxite mining and alumina refining require the maintenance of effective control measures. PMID:24806720

Catalytic removal of methane and NO{sub x} in lean-burn natural-gas engine exhaust; Elimination par catalyse du methane et des NO{sub x} dans les echappements de moteur au gaz naturel a basse combustion

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, H.; Satokawa, S.; Yahagi, M.; Yamaseki, K.; Hoshi, F.; Uchida, H.; Yokota, H. [Tokyo Gas Co., Ltd. (Japan)

2000-07-01

We have developed a new catalytic system to reduce the emissions of hydrocarbons, carbon monoxide (CO), and nitrogen oxides (NO{sub x}) contained in the exhaust gases from a lean-burn natural-gas engine. Catalytic oxidation of unburned hydrocarbons and CO in the exhaust has been studied for noble metals supported on alumina. (1) A low-loading catalyst comprising platinum supported on alumina (Pt/alumina) was efficient for the oxidation of CO and hydrocarbons without methane. The CO conversions were maintained at more than 98 % for 20,000 hours over the Pt/alumina. (2) A catalyst comprising platinum and palladium supported on alumina (Pt-Pd/alumina) exhibited higher levels of oxidation of hydrocarbons (including methane) than a catalyst comprising only palladium supported on alumina (Pd/alumina). Its oxidation also lasted longer. The combined effects of the platinum and palladium metals achieved high sulfur dioxide resistance. Increasing the palladium content in the Pt-Pd/alumina catalyst increased the level of oxidation and extended the lifetime of the catalyst. (3) A catalyst comprising silver supported on alumina (Ag/alumina) was effective at reducing the amount of NO{sub X} by using the unburned hydrocarbons in the exhaust gas. The NO{sub x} conversions over Ag/alumina were maintained at more than 30 % for 3,500 hours. We describe a total clean-up system consisting of a Ag/alumina catalyst and a Pt-Pd/alumina catalyst in series on the exhaust gas stream. (authors)

Dissolution kinetics for alumina in cryolite melts. Distribution of alumina in the electrolyte of industrial aluminium cells

Energy Technology Data Exchange (ETDEWEB)

Kobbeltvedt, Ove

1997-12-31

This thesis contributes to the understanding of which factors determine the rate of dissolution of alumina added to the bath in alumina reduction cells. Knowing this may help reduce the occurrences of operation interruptions and thus make it possible to produce aluminium using less energy. When alumina powder was added to a stirred cryolite melt, the alumina dissolved in two distinct main stages. In the first stage, the dissolution rate was very high, which reflects dissolution of single alumina grains that are being dispersed in the bath upon addition. In the second stage, lumps of alumina infiltrated with bath dissolved at a rate considerably slower than that of the first stage. The formation of these alumina agglomerates is the most important contributor to slow dissolution. The parameters varied in the experiments were convection, batch size, and temperature of the bath and of the added alumina. Increased gas stirring of the bath speeded up dissolution in both stages but the size of the batch was of little significance. Increasing the bath temperature had no effect in the first stage but speeded up dissolution considerably in the second stage. Compared to adding alumina at room temperature, preheating it to a high temperature (600 {sup o}C) increased the dissolution rate in the first stage while preheating to lower temperatures (100-300 {sup o}C) decreased the dissolution rate. In the second stage, preheating slowed the dissolution. The two latter phenomena of reduced dissolution rates are ascribed to the removal of moisture from the alumina upon preheating. The bath flow and the distribution of alumina in the bath were measured in four different types of cells. It was found that if a certain asymmetry of the magnetic field traverse to the cell was present, due to the presence of risers, then loops of high velocity bath flow occurred near the short ends of the cell. Thus, alumina added near the short ends is effectively transferred away from the feeding

Alumina Yield in the Bayer Process

Science.gov (United States)

Den Hond, R.

The alumina industry has historically been able to reduce alumina production costs, by increasing the liquor alumina yield. To know the potential for further yield increases, the phase diagram of the ternary system Na2O-Al2O -H2O at various temperature levels was analysed. It was found that the maximum theorical precipitation alumina yield is 160 g/l, while that for digestion was calculated to be 675 g/l.

Electron beam application for regeneration of catalysts used in refinery cracking units

International Nuclear Information System (INIS)

Kondo, Fernando Mantovani; Duarte, Celina Lopes; Sato, Ivone Mulako; Salvador, Vera Lucia Ribeiro; Calvo, Wilson Aparecido Parejo

2013-01-01

A catalyst is a substance that alters the rate of a reaction. The process of catalysis is essential to the modern day manufacturing industry, mainly in Fluid Catalytic Cracking Process (FCC) units. However, long-term exploitation of oil and gas processing catalysts leads to formation of carbon-and sulfur-containing structures of coke and dense products on the catalyst surface. They block reactive catalyst sites and reduce the catalytic activity. The main advantage of radiation processing by electron beam (EB) and gamma rays is chain cracking reaction in crude oil. Otherwise, under exposure to ionic radiation, considerable structure modification of equilibrium silica-alumina catalyst from FCC process may occur, in addition to the removal of impurities. The conditions applied in the irradiation range (20-150 kGy) of gamma rays and electron beam were not sufficient to alter the structure of the catalyst, whether for removal of the contaminant nickel, a major contaminant of the FCC catalyst, either to rupture of the crystalline structure either for the future reutilization of chemical elements. Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Energy Dispersive X-Ray Fluorescence Spectrometry (EDXRFS) analysis were used to characterize and evaluate effects of radiation processing on equilibrium catalysts purification. To evaluate and comprehend the reactive catalyst sites, Scanning Electron Microscopy (SEM) and particle size distribution analyses were carried out. (author)

Are mediation clauses binding and mandatory?

Directory of Open Access Journals (Sweden)

Constantinescu Miruna

2017-06-01

Full Text Available This study analyses the legal force of mediation clauses in the common law systems and civil law systems with a main focus on the Romanian approach. First, the introductory section illustrates the paradox between the concept of binding and mandatory effect and the mediation mechanism, a voluntary manner to settle disputes. Notwithstanding, the possibility to coerce the parties to engage into a mediation, the voluntary character of the process is illustrated by the parties’ freedom to decide whether they settle or not. Second, the role of mediation clause is analysed and its advantages are briefly described. Third, the non-compliance of the prior mediation mechanism is presented, the starting point of the discussion being represented by the manner in which the parties drafted the mediation clause. A carefully drafted mediation clause, reflecting the parties’ consent, can determine a court or an arbitral tribunal to enforce such clause. Fourth, the study ends by mentioning the approach adopted by different national courts, emphasizing the Romanian legal perspective.

Oxygen exchange between C18O2 and ''acidic'' oxide and zeolite catalysts

International Nuclear Information System (INIS)

Peri, J.B.

1975-01-01

The exchange of oxygen between C 18 O 2 and several high-area oxides, including silica, γ-alumina, silica--alumina, and zeolite catalysts, was studied. Infrared spectra of adsorbed CO 2 and of surface ''carbonates'' were used to follow the rate of oxygen exchange and investigate the nature of unusually exchangeable surface oxide ions, present at low concentrations. Interaction of CO 2 with the surface typically produced initial exchange of one oxygen atom, as expected from interaction with a single oxide ion (CO 2 + O 2- reversible CO 3 2- ), and the number of exchangeable ions increased with increasing temperature. The rate of oxygen exchange did not correlate with chemisorption to form stable surface carbonates or with the extent of strong physical adsorption of CO 2 . With dry silica, exchange was insignificant below 600 0 ; with catalytically active zeolites and dry γ-alumina, it was detectable at 200 0 and fairly rapid at 300--400 0 . Silica--alumina required 100--150 0 higher temperature for exchange than did an active zeolite. Activity for cracking and other hydrocarbon reactions may be related to the ease of exchange of some surface oxide ions with CO 2 . Active zeolites have reactive oxide sites resembling those on dry γ-alumina, but such sites on zeolites are probably less-readily eliminated by chemisorption of H 2 O or other compounds. (U.S.)

Sintering behaviour of spinel–alumina composites

Indian Academy of Sciences (India)

% alumina dissolves in spinel (MgAl2O4) at 1600°C. Solid solubility of alumina in spinel decreases rapidly with decreasing temperature, which causes exsolution of alumina from spinel phase. Previous work of one of the authors revealed that ...

Synthesis of Alumina using the solvo thermal method

International Nuclear Information System (INIS)

Meor Yusoff Meor Sulaiman; Masliana Muslimin

2007-01-01

The paper describes work done on synthesis of α- and β-alumina by using the solvo thermal technique. Synthesis of both these aluminas involves the transition reactions of the aluminium hydroxide into alumina by a dehydroxylation process. As there are many forms of transition aluminas produced during this process, x-ray diffraction (XRD) technique was used to identify α-alumina and β-alumina. After establishing the optimum conditions for the production of a single-phase α- and β-aluminas, characteristic study on the product was performed. An important parameter in establishing nano sized powders is their crystallite size and analysis of the β-alumina shows that it is a nano sized powder with a size of 28 nm while the α-alumina has a crystallite size of 200 nm. Other properties analysed include morphology, surface area and particle size. (author)

Isobutane alkylation over solid catalysts

Energy Technology Data Exchange (ETDEWEB)

Kozorezov, Y.I.; Lisin, V.I.

1979-05-01

Commercial alumina modified with 6Vertical Bar3< by wt boron trifluoride was active in isobutane alkylation with ethylene in a flow reactor at 5:1 isobutane-ethylene and 5-20 min reaction time. The reaction rate was first-order in ethylene and increased with increasing temperature (20/sup 0/-80/sup 0/C) and ethylene pressure (0.2-3 atm). The calculated activation energy was 8.4 kj. Kinetic data and the activity of tert.-butyl chloride, but not ethyl chloride as alkylating agents in place of ethylene suggested a carbonium-ion chain mechanism involving both surface and gas-phase reactions. The ethylene-based yield of the alkylate decreased from 132 to 41Vertical Bar3< by wt after nine hours on stream, and its bromine number increased from 0.2 to 1 g Br/sub 2//100 ml. This inhibition was attributed to adsorption on the active acidic sites of the reaction products, particularly C/sub 10//sup +/ olefins. Catalyst stabilization could probably be achieved by selecting an appropriate solvent that would continuously desorb the inhibiting products from the catalyst surface.

48 CFR 52.252-2 - Clauses Incorporated by Reference.

Science.gov (United States)

2010-10-01

..., with the same force and effect as if they were given in full text. Upon request, the Contracting Officer will make their full text available. Also, the full text of a clause may be accessed... (CONTINUED) CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions and Clauses 52...

Reuse of activated alumina

Energy Technology Data Exchange (ETDEWEB)

Hobensack, J.E. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

1991-12-31

Activated alumina is used as a trapping media to remove trace quantities of UF{sub 6} from process vent streams. The current uranium recovery method employs concentrated nitric acid which destroys the alumina pellets and forms a sludge which is a storage and disposal problem. A recently developed technique using a distilled water rinse followed by three dilute acid rinses removes on average 97% of the uranium, and leaves the pellets intact with crush strength and surface area values comparable with new material. Trapping tests confirm the effectiveness of the recycled alumina as UF{sub 6} trapping media.

Characterization of Cu/CeO2/Al2O3 catalysts by temperature programmed reduction and activity for CO oxidation

International Nuclear Information System (INIS)

Cataluna, Renato; Baibich, Ione M.; Dallago, R.M.; Picinini, C.; Martinez-Arias, A.; Soria, J.

2001-01-01

The kinetic parameters for the CO oxidation reaction using copper/alumina-modified ceria as catalysts were determined. The catalysts with different concentrations of the metals were prepared using impregnation methods. In addition, the reduction-oxidation behaviour of the catalysts were investigated by temperature-programmed reduction. The activity results show that the mechanism for CO oxidation is bifunctional: oxygen is activated on the anionic vacancies of ceria surface, while carbon monoxide is adsorbed preferentially on the higher oxidation copper site. Therefore, the reaction occurs on the interfacial active centers. Temperatures-programmed Reduction patterns show a higher dispersion when cerium oxide is present. (author)

Hydrogenation of carbon monoxide on WO/sub 3/-Supported ruthenium catalysts

Energy Technology Data Exchange (ETDEWEB)

Yoshinari, Tomohiro; Suganuma, Fujio; Sera, Chikara

1988-01-01

In this study, a WO/sub 3/-supported catalyst was prepared to conduct hydrogenation of CO for examining the product distribution and composition of hydrocarbons, using a gamma-alumina-supported catalyst for comparison. These catalysts were used under pressure to conduct a distributive reaction and the desorbing behavior of CO or H/sub 2/ at elevated temperature was measured to examine the influence of the type of carrier or the method of preparation on the activity and the distribution of products formed. The WO/sub 3/-supported catalyst gave a carbon chain length distribution that did not comply with the rule of Schulz-Flory, giving a composition richer in the isomers. Carbon number distribution is affected by Ru-dispersion, and the selectivity of isomers depends on the acidity of the carrier. Formed products distribution of the WO/sub 3/-supported reaction is attributable to the secondary reaction, which relates to the acidic point of the carrier, of the primary product formed on the metal. (7 figs, 4 tabs, 18 refs)

The Application of Moessbauer Emission Spectroscopy to Industrial Cobalt Based Fischer-Tropsch Catalysts

International Nuclear Information System (INIS)

Loosdrecht, J. van de; Berge, P. J. van; Craje, M. W. J.; Kraan, A. M. van der

2002-01-01

The application of Moessbauer emission spectroscopy to study cobalt based Fischer-Tropsch catalysts for the gas-to-liquids process was investigated. It was shown that Moessbauer emission spectroscopy could be used to study the oxidation of cobalt as a deactivation mechanism of high loading cobalt based Fischer-Tropsch catalysts. Oxidation was observed under conditions that are in contradiction with the bulk cobalt phase thermodynamics. This can be explained by oxidation of small cobalt crystallites or by surface oxidation. The formation of re-reducible Co 3+ species was observed as well as the formation of irreducible Co 3+ and Co 2+ species that interact strongly with the alumina support. The formation of the different cobalt species depends on the oxidation conditions. Iron was used as a probe nuclide to investigate the cobalt catalyst preparation procedure. A high-pressure Moessbauer emission spectroscopy cell was designed and constructed, which creates the opportunity to study cobalt based Fischer-Tropsch catalysts under realistic synthesis conditions.

Hydrogen Temperature-Programmed Desorption in Platinum Catalysts: Decomposition and Isotopic Exchange by Spillover Hydrogen of Chemisorbed Ammonia.

NARCIS (Netherlands)

Koningsberger, D.C.; Miller, J.T.; Meyers, B.L.; Barr, M.K.; Modica, F.S.

1996-01-01

H{2}-TPD of Pt/alumina catalysts display multiple hydrogendesorptions. In addition to chemisorbed hydrogen (Peak I) atapproximately 175}o{C, there is a small hydrogen desorption (PeakII) at about 250}o{C and a large, irreversible hydrogen desorption(Peak III) at 450}o{C. The quantity of hydrogen

The black rock series supported SCR catalyst for NO x removal.

Science.gov (United States)

Xie, Bin; Luo, Hang; Tang, Qing; Du, Jun; Liu, Zuohua; Tao, Changyuan

2017-09-01

Black rock series (BRS) is of great potential for their plenty of valued oxides which include vanadium, iron, alumina and silica oxides, etc. BRS was used for directly preparing of selective catalytic reduction (SCR) catalyst by modifying its surface texture with SiO 2 -TiO 2 sols and regulating its catalytic active constituents with V 2 O 5 and MoO 3 . Consequently, 90% NO removal ratio was obtained within 300-400 °C over the BRS-based catalyst. The structure and properties of the BRS-based catalyst were characterized by the techniques of N 2 adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (H 2 -TPR), and NH 3 -temperature programmed desorption (NH 3 -TPD). The results revealed that the BRS-based catalyst possesses favorable properties for NO x removal, including highly dispersed active components, abundant surface-adsorbed oxygen O α , well redox property, and numerous Brønsted acid sites. Particularly, the BRS-based catalyst exhibited considerable anti-poisoning performance compared with commercial TiO 2 -based catalyst. The former catalyst shows a NO conversion surpassing 80% from 300 to 400 °C for potassium poisoning, and a durability of SO 2 and H 2 O exceeding 85% at temperatures from 300 to 450 °C.

Toluene destruction in the Claus process by sulfur dioxide: A reaction kinetics study

KAUST Repository

Sinha, Sourab

2014-10-22

The presence of aromatics such as benzene, toluene, and xylene (BTX) as contaminants in the H2S gas stream entering Claus sulfur recovery units has a detrimental effect on catalytic reactors, where BTX forms soot particles and clogs and deactivates the catalysts. BTX oxidation, before they enter catalyst beds, can solve this problem. A theoretical investigation is presented on toluene oxidation by SO2. Density functional theory is used to study toluene radical (benzyl, o-methylphenyl, m-methylphenyl, and p-methylphenyl)-SO2 interactions. The mechanism begins with SO2 addition on the radical through one of the O atoms rather than the S atom. This exothermic reaction involves energy barriers of 4.8-6.1 kJ/mol for different toluene radicals. Thereafter, O-S bond scission takes place to release SO. The reaction rate constants are evaluated to facilitate process simulations. Among four toluene radicals, the resonantly stabilized benzyl radical exhibited lowest SO2 addition rate. A remarkable similarity between toluene oxidation by O2 and by SO2 is observed.

Toluene destruction in the Claus process by sulfur dioxide: A reaction kinetics study

KAUST Repository

Sinha, Sourab; Raj, Abhijeet Dhayal; Alshoaibi, Ahmed S.; Alhassan, Saeed M.; Chung, Suk-Ho

2014-01-01

The presence of aromatics such as benzene, toluene, and xylene (BTX) as contaminants in the H2S gas stream entering Claus sulfur recovery units has a detrimental effect on catalytic reactors, where BTX forms soot particles and clogs and deactivates the catalysts. BTX oxidation, before they enter catalyst beds, can solve this problem. A theoretical investigation is presented on toluene oxidation by SO2. Density functional theory is used to study toluene radical (benzyl, o-methylphenyl, m-methylphenyl, and p-methylphenyl)-SO2 interactions. The mechanism begins with SO2 addition on the radical through one of the O atoms rather than the S atom. This exothermic reaction involves energy barriers of 4.8-6.1 kJ/mol for different toluene radicals. Thereafter, O-S bond scission takes place to release SO. The reaction rate constants are evaluated to facilitate process simulations. Among four toluene radicals, the resonantly stabilized benzyl radical exhibited lowest SO2 addition rate. A remarkable similarity between toluene oxidation by O2 and by SO2 is observed.

Wear of alumina on alumina total hip prosthesis - effect of lubricant on hip simulator test

Energy Technology Data Exchange (ETDEWEB)

Ueno, M.; Amino, H. [Kyocera Corp., Fushimi, Kyoto (Japan). Bioceram Div.; Oonishi, H. [Dept. of Orthopaedic Surgery, Artificial Joint Sect. and Biomat. Res. Lab., Osaka Minami National Hospital, Osaka (Japan); Clarke, I.C.; Good, V. [Dept. of Orthopaedic Surgery, Loma Linda Univ. Medical Center, CA (United States)

2001-07-01

The complex wear-friction-lubrication behavior of alumina on alumina combination in total hip prostheses (THP) was investigated using a hip joint simulator. The objectives of this study were to evaluate the effect of the ball/cup clearance and of the lubricant conditions. Alumina bearings were categorized in three diametrical clearances, 20-30, 60-70 and 90-100 micrometer, three each and wear tests were carried out with 90% bovine serum. There was no significant difference between three groups. Volumetric wear in the run-in phase for all tested nine ceramic liners averaged 0.27mm{sup 3}/million cycles and in the steady-state phase averaged 0.0042mm{sup 3}/million cycles. In addition to the 90% serum, 27% serum and saline were used as the lubricant for evaluate the effect of serum concentration on alumina on alumina wear couples. The wear test results showed that in all tested conditions the wear trends of alumina BEARING were bi-phasic and wear volume could be affected by the serum concentration. Both ''Run-in'' and ''Steady-state'' wear rates in 90% bovine serum were three times higher than those in saline. (orig.)

High field 27Al MAS NMR and TPD studies of active sites in ethanol dehydration using thermally treated transitional aluminas as catalysts

Energy Technology Data Exchange (ETDEWEB)

Hu, Jian Zhi; Xu, Suochang; Kwak, Ja Hun; Hu, Mary Y.; Wan, Chuan; Zhao, Zhenchao; Szanyi, Janos; Bao, Xinhe; Han, Xiuwen; Wang, Yong; Peden, Charles H. F.

2016-04-01

Gamma-, sigma- and theta-Al2O3 are well known metastable “transitional” alumina structural polymorphs. Upon heating, Al2O3 transitions to the so-called and Al2O3 polymorphs and finally forms the thermally stable Al2O3. The poorly developed crystallinity and co-existence of the , , and Al2O3 prior to forming all Al2O3, making it difficult to characterize the structures as well as to quantify the various phases of the transition alumina. As a result, there are significant controversies in the literatures. In this work, a detailed NMR analysis was carried out at high magnetic field on three special aluminum oxide samples where the, , , Al2O3 phases are made dominant, respectively, by controlling the synthesis conditions. The goal is to simplify, including making unambiguous, spectral assignments in 27Al MAS NMR spectra of transition alumina that have not yet been commonly agreed previously. Specifically, quantitative 1D 27Al MAS NMR was used to quantify the ratios of the different alumina structural units, 2D MQMAS 27Al MAS was used for obtaining the highest spectral resolution to guide the analysis of the 1D spectrum, and a saturation pulse sequence was integrated into the 1D NMR to select the amorphous structures, including obtain spectra where the penta-coordinate sites are observed with enhanced relative intensity. Collectively, this study uniquely assigns Al-peaks (both octahedral and tetrahedral) to the Al2O3 and the Al2O3 phases and offers a new way of understanding, including quantifying, the different structural units and sites in transition alumina samples.

Comparative study of the methane and methanol mass transfer in the mesoporous H-ZSM-5/alumina extruded pellet

Science.gov (United States)

Zhokh, Alexey A.; Strizhak, Peter E.

2018-07-01

H-ZSM-5/alumina catalyst pellet was prepared using extrusion method. The as-prepared mesoporous material was characterized using nitrogen adsorption, IR, XRD, and TEM methods. Transport of methane and methanol in the obtained H-ZSM-5/alumina extruded grain was studied. We demonstrate that the methanol transport may be described by the time-fractional diffusion equation in a fairly good manner. The measured value of the fractional order of the time-fractional derivative reveals the fast super-diffusive regime of the methanol transport in the mesoporous solid. Contrary, the methane transport has been found to follow a standard diffusion and described by the second Fick's law. These findings show that mass transfer kinetics is characterized by the order of the temporal derivative. The latter is a unique property of the individual porous media and the diffusing agent.

Comparative study of the methane and methanol mass transfer in the mesoporous H-ZSM-5/alumina extruded pellet

Science.gov (United States)

Zhokh, Alexey A.; Strizhak, Peter E.

2018-01-01

H-ZSM-5/alumina catalyst pellet was prepared using extrusion method. The as-prepared mesoporous material was characterized using nitrogen adsorption, IR, XRD, and TEM methods. Transport of methane and methanol in the obtained H-ZSM-5/alumina extruded grain was studied. We demonstrate that the methanol transport may be described by the time-fractional diffusion equation in a fairly good manner. The measured value of the fractional order of the time-fractional derivative reveals the fast super-diffusive regime of the methanol transport in the mesoporous solid. Contrary, the methane transport has been found to follow a standard diffusion and described by the second Fick's law. These findings show that mass transfer kinetics is characterized by the order of the temporal derivative. The latter is a unique property of the individual porous media and the diffusing agent.

48 CFR 11.304 - Contract clause.

Science.gov (United States)

2010-10-01

... Section 11.304 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION ACQUISITION PLANNING DESCRIBING AGENCY NEEDS Acceptable Material 11.304 Contract clause. Insert the clause at 52.211-5, Material Requirements, in solicitations and contracts for supplies that are not commercial items. ...

48 CFR 22.1408 - Contract clause.

Science.gov (United States)

2010-10-01

... Section 22.1408 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SOCIOECONOMIC PROGRAMS APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Employment of Workers with Disabilities 22.1408 Contract clause. (a) Insert the clause at 52.222-36, Affirmative Action for Workers with...

48 CFR 9.308 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Contract clauses. 9.308 Section 9.308 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION ACQUISITION PLANNING CONTRACTOR QUALIFICATIONS First Article Testing and Approval 9.308 Contract clauses. ...

Study on alumina-alumina brazing for application in vacuum chambers of proton synchrotron

International Nuclear Information System (INIS)

Yadav, D.P.; Kaul, R.; Ganesh, P.; Shiroman, Ram; Tiwari, Pragya; Sridhar, R.; Kukreja, L.M.

2013-01-01

The paper describes an experimental study to standardize vacuum brazing process to obtain satisfactory high purity alumina brazed joints for application in rapid cycle proton synchrotron machine. Two different brazing routes, adopted for making alumina-alumina brazed joints, included (i) multi-step Mo-Mn metallization and brazing with BVAg-8 alloy and (ii) advanced single-step active brazing with CuSil-ABA alloy. Brazed alumina specimens, prepared by both the routes, yielded ultra high vacuum compatible, helium leak tight and bakeable joints. Active-brazed specimens exhibited satisfactory strength values in tensile and four-point bend tests. Metallized-brazed specimens, although exhibited relatively lower tensile strength than the targeted value, displayed satisfactory flexural strength in four-point bend test. The results of the study demonstrated that active brazing is the simple and cost effective alternative to conventional metallization route for producing satisfactory brazed joints for application in rapid cycle proton synchrotron machine. (author)

48 CFR 970.0407-1-3 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.0407... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Administrative Matters 970.0407-1-3 Contract clause. The contracting officer shall insert the clause at 970.5204-3, Access to and Ownership of Records...

The thermal stability and catalytic performance of Ce-Zr promoted Rh-Pd/γ-Al2O3 automotive catalysts

International Nuclear Information System (INIS)

Wu Xiaodong; Xu Luhua; Weng Duan

2004-01-01

The noble metals (Rh, Pd) supported on alumina promoted with Ce-Zr mixed oxides were investigated as catalysts under diverse oxidants/reductants ratios of simulated automotive exhaust feed gas. Aging test was performed in air at 1000 deg. C for 20 h. Both fresh and aged catalysts, as well as alumina-supported Ce-Zr mixed powders, were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS). The results confirmed the oxygen storage capacity of Ce-Zr mixed oxides favored CO, C 3 H 8 and NO conversions in stationary versus dynamic stoichiometric operation. The accelerated aging of the systems produced inconspicuous effect on the phase structure, specific surface area and chemical state of these samples. Accordingly, the aged samples still showed low light-off temperature and broad λ-window, which suggested the relative low relevance of the thermal degradation on the overall catalytic performance of the system

Preparation and characterization of stable copper/zinc oxide/alumina catalysts for methanol synthesis

Energy Technology Data Exchange (ETDEWEB)

Hoeppener, R H; Doesburg, E B; Scholten, J J

1986-08-15

A series of Cu/ZnO/Al/sub 2/O/sub 3/ catalysts for the low pressure methanol synthesis has been prepared by coprecipitation with a sodium carbonate solution from solutions of a mixture of the corresponding metal nitrates, followed by drying, calcination and reduction. The catalysts and their precursors were analyzed by techniques like X-ray diffraction, X-ray line broadening, differential thermal analysis, chemical analysis, adsorptive decomposition of N/sub 2/O and B.E.T.-measurements. The catalytic activity for the methanol synthesis was determined in a flow reactor under industrial conditions. Depending on the metal ion ratio in the initial metal nitrate solutions different compounds were formed during coprecipitation, like rosasite, malachite, Cu, Zn-hydrotalcite and a ternary compound which was called roderite. Its structure is unknown and it contains, besides Zn/sup 2+/, up to 28 at% Cu/sup 2+/ and up to 17 at% Al/sup 3+/. Addition of 7 at% Mg/sup 2+/ stabilizes the Cu, Zn-hydrotalcite structure but leads to a drastic decrease in catalytic activity. The rate of methanol production depends on the phase composition of the precursors. Rosasite containing precursors give the highest activity; hydrotalcite proves to be an excellent catalyst stabilizer which evokes the formation of small Cu and ZnO particles. Mg/sup 2+/ inhibits methanol production. 6 figs., 1 tab., 18 refs.

Kinetics modeling of ethylbenzene dehydrogenation to styrene over a mesoporous alumina supported iron catalyst

KAUST Repository

Hossain, Mohammad M.

2012-10-01

The kinetics of ethylbenzene (EB) dehydrogenation over a FeO x-meso-Al 2O 3 catalyst is studied. The models were developed based on physicochemical characterization and a CREC fluidized Riser Simulator data. N 2 adsorption shows that the synthesized FeO x-meso-Al 2O 3 catalyst is mesoporous with pore size between 9 and 35nm. TPR profile indicates that iron on meso-Al 2O 3 forms easily reducible nanostructured crystals which is confirmed by TEM image. NH 3- and CO-TPD analysis, respectively reveals the availability of both acidic and basic sites. The dehydrogenation of ethylbenzene on FeO x-meso-Al 2O 3 catalyst mainly gives styrene (∼99%) while a small amount of benzene, toluene and coke are also detected. Based on the experimental observations two Langmuir-Hinshelwood type kinetics models are formulated. The possible catalyst deactivation is expressed as function of EB conversion. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one type site Langmuir-Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the physical constraints. The activation energy for the formation of styrene (80kJ/mol) found to be significantly lower than that of the undesired products benzene (144kJ/mol) and toluene (164kJ/mol). The estimated heat of adsorptions of EB and ST are found to be 55kJ/mol and 19kJ/mol, respectively. © 2012 Elsevier B.V.

Fischer-Tropsch diesel production over calcium-promoted Co/alumina catalyst: Effect of reaction conditions

Energy Technology Data Exchange (ETDEWEB)

A.R. de la Osa; A. De Lucas; A. Romero; J.L. Valverde; P. Sanchez [University of Castilla-La Mancha, Ciudad Real (Spain). Chemical Engineering Department

2011-05-15

The effects of reaction conditions on the Fischer-Tropsch activity and product distribution of an alkali-earth metal promoted cobalt based catalyst were studied. The influence of the promoter on the reducibility and cobalt particle size was studied by different techniques, including N{sub 2} adsorption, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption and acid-base titrations. Experiments were carried out on a bench-scale fixed bed reactor and catalysts were prepared by incipient wetness impregnation. It was observed that addition of a small amount of calcium oxide as a promoter (0.6 wt.%) improved the cobalt oxide reducibility and reduced the formation of cobalt-aluminate species. A positive correlation between basicity and particle size was observed. In terms of FTS results, CO conversion and C{sub 5}{sup +} selectivity were found to be enhanced by the addition of this promoter. It was important to note that the addition of calcium shifted the distribution to mainly C{sub 16}-C{sub 18} hydrocarbons fraction, which could be greatly considered for a diesel formulation. Furthermore, the variation of the reaction conditions seemed to influence product distribution in a lesser extent than unpromoted catalyst. Also, a displacement of hydrocarbon distribution to higher molecular weight with decreasing space velocity and temperature was observed. Moreover, the addition of calcium to the cobalt based catalyst was found to greatly maintain selectivity to C{sub 5}{sup +} for a wide range of H{sub 2}/CO molar ratios. 60 refs., 10 figs., 5 tabs.

48 CFR 923.903 - Contract clause.

Science.gov (United States)

2010-10-01

... ENVIRONMENT, CONSERVATION, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Contractor Compliance With Environmental Management Systems § 923.903 Contract clause. The FAR Environmental Management Systems clause at.... Some DOE sites have a single Environmental Management System for the site while others have separate...

48 CFR 747.507 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 747.507 Section 747.507 Federal Acquisition Regulations System AGENCY FOR INTERNATIONAL DEVELOPMENT CONTRACT MANAGEMENT TRANSPORTATION Ocean Transportation by U.S.-Flag Vessels 747.507 Contract clauses. Contracting...

48 CFR 937.7040 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 937.7040... CONTRACTING SERVICE CONTRACTING Protective Services Contracting 937.7040 Contract clauses. The contracting... services” in all protective services solicitations and contracts involving DOE-owned facilities requiring...

48 CFR 745.106 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 745.106 Section 745.106 Federal Acquisition Regulations System AGENCY FOR INTERNATIONAL DEVELOPMENT CONTRACT MANAGEMENT GOVERNMENT PROPERTY General 745.106 Contract clauses. (a) The contracting officer shall insert the...

48 CFR 908.1104 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 908.1104 Section 908.1104 Federal Acquisition Regulations System DEPARTMENT OF ENERGY COMPETITION ACQUISITION PLANNING REQUIRED SOURCES OF SUPPLIES AND SERVICES Leasing of Motor Vehicles 908.1104 Contract clauses. (f...

48 CFR 716.406 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 716.406 Section 716.406 Federal Acquisition Regulations System AGENCY FOR INTERNATIONAL DEVELOPMENT CONTRACTING METHODS AND CONTRACT TYPES TYPES OF CONTRACTS Cost Reimbursement Contracts 716.406 Contract clauses. The...

48 CFR 916.307 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 916.307 Section 916.307 Federal Acquisition Regulations System DEPARTMENT OF ENERGY CONTRACTING METHODS AND CONTRACT TYPES TYPES OF CONTRACTS Cost-Reimbursement Contracts 916.307 Contract clauses. (g) Insert the...

48 CFR 704.404 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 704.404... ADMINISTRATIVE MATTERS Safeguarding Classified Information Within Industry 704.404 Contract clause. If the contract involves access to classified (“Confidential”, “Secret”, or “Top Secret”), or administratively...

48 CFR 833.215 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 833.215 Section 833.215 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS GENERAL CONTRACTING REQUIREMENTS PROTESTS, DISPUTES, AND APPEALS Disputes and Appeals 833.215 Contract clause. The contracting...

48 CFR 947.7002 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 947.7002 Section 947.7002 Federal Acquisition Regulations System DEPARTMENT OF ENERGY CONTRACT MANAGEMENT TRANSPORTATION Foreign Travel 947.7002 Contract clause. When foreign travel may be required under the contract...

48 CFR 432.412 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Contract clause. 432.412 Section 432.412 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE GENERAL CONTRACTING REQUIREMENTS CONTRACT FINANCING Advance Payments for Non-Commercial Items 432.412 Contract clause. The decision...

48 CFR 244.403 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Contract clause. 244.403... OF DEFENSE CONTRACT MANAGEMENT SUBCONTRACTING POLICIES AND PROCEDURES Subcontracts for Commercial Items and Commercial Components 244.403 Contract clause. (1) 252.225-7009, Restriction on Acquisition of...

Constraint specialisation in Horn clause verification

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick

2017-01-01

We present a method for specialising the constraints in constrained Horn clauses with respect to a goal. We use abstract interpretation to compute a model of a query–answer transformed version of a given set of clauses and a goal. The constraints from the model are then used to compute...... a specialised version of each clause. The effect is to propagate the constraints from the goal top-down and propagate answer constraints bottom-up. The specialisation procedure can be repeated to yield further specialisation. The approach is independent of the abstract domain and the constraint theory...

48 CFR 970.2201-1-3 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 970.2201... SUPPLEMENTARY REGULATIONS DOE MANAGEMENT AND OPERATING CONTRACTS Application of Labor Policies 970.2201-1-3 Contract clause. In addition to the clause at 48 CFR 52.222-1, Notice to the Government of Labor Disputes...

Metallorganic routes to nanoscale iron and titanium oxide particles encapsulated in mesoporous alumina: formation, physical properties, and chemical reactivity.

Science.gov (United States)

Schneider, J J; Czap, N; Hagen, J; Engstler, J; Ensling, J; Gütlich, P; Reinoehl, U; Bertagnolli, H; Luis, F; de Jongh, L J; Wark, M; Grubert, G; Hornyak, G L; Zanoni, R

2000-12-01

Iron and titanium oxide nanoparticles have been synthesized in parallel mesopores of alumina by a novel organometallic "chimie douce" approach that uses bis(toluene)iron(0) (1) and bis(toluene)titanium(0) (2) as precursors. These complexes are molecular sources of iron and titanium in a zerovalent atomic state. In the case of 1, core shell iron/iron oxide particles with a strong magnetic coupling between both components, as revealed by magnetic measurements, are formed. Mössbauer data reveal superparamagnetic particle behavior with a distinct particle size distribution that confirms the magnetic measurements. The dependence of the Mössbauer spectra on temperature and particle size is explained by the influence of superparamagnetic relaxation effects. The coexistence of a paramagnetic doublet and a magnetically split component in the spectra is further explained by a distribution in particle size. From Mössbauer parameters the oxide phase can be identified as low-crystallinity ferrihydrite oxide. In agreement with quantum size effects observed in UV-visible studies, TEM measurements determine the size of the particles in the range 5-8 nm. The particles are mainly arranged alongside the pore walls of the alumina template. TiO2 nanoparticles are formed by depositing 2 in mesoporous alumina template. This produces metallic Ti, which is subsequently oxidized to TiO2 (anatase) within the alumina pores. UV-visible studies show a strong quantum confinement effect for these particles. From UV-visible investigations the particle size is determined to be around 2 nm. XPS analysis of the iron- and titania- embedded nanoparticles reveal the presence of Fe2O3 and TiO2 according to experimental binding energies and the experimental line shapes. Ti4+ and Fe3+ are the only oxidation states of the particles which can be determined by this technique. Hydrogen reduction of the iron/iron-oxide nanoparticles at 500 degrees C under flowing H2/N2 produces a catalyst, which is active

Modification of sulphide catalysts for hydro-treatment by addition of fluorine; Modification de catalyseurs sulfure pour l'hydrotraitement par ajout de fluor

Energy Technology Data Exchange (ETDEWEB)

Fischer, L

1999-12-15

Ni, Mo and NiMo sulphide catalysts supported on alumina were modified with fluorine in the range of 0.8 to 17 weight % F and tested in ortho-xylene hydrogenation under 60 bar total pressure and in presence of 1 bar H{sub 2}S. A positive effect of fluorine on Ni and NiMo catalytic activity was found. The tested catalysts were characterised by electronic microscopy and X-ray-photoelectron spectroscopy. The observed variations in dispersion and sulfidation degree of the active phase are not important enough to explain the good catalytic activity. The catalytic test was adapted in a way that allows a determination of electronic effects on sulphide catalysts under typical hydro-treating conditions. The product distribution in cis- and trans- 1,2-dimethyl-cyclohexane was found to be sensitive to the electronic state of the catalyst's active site. This was verified by addition of electron-donating NH{sub 3} as well as other evidences. According to this test, fluorine acts as an electron-donator on Ni and NiMo catalysts' active sites. A volcano curve of catalytic activity in function of electronic density is obtained for MoS{sub 2} based catalysts (Mo and NiMo), suggesting the existence of an optimum electronic density which would be achieved by introduction of about 6 weight % F into a NiMo catalyst. Characterization by infrared spectroscopy of adsorbed CO confirms the electron-donating effect of fluorine. Fluoridation tests of bulk catalysts permitted to exclude a bonding between fluorine and the active sulphide phase in absence of a support. It is suggested that electron-donating fluoride located on the surface of alumina, the interaction with nickel being of van-der-Waals type. (author)

48 CFR 803.570-2 - Contract clause.

Science.gov (United States)

2010-10-01

... BUSINESS PRACTICES AND PERSONAL CONFLICTS OF INTEREST Other Improper Business Practices 803.570-2 Contract clause. The contracting officer shall insert the clause at 852.203-70, Commercial advertising, in...

48 CFR 503.570-2 - Contract clause.

Science.gov (United States)

2010-10-01

... BUSINESS PRACTICES AND PERSONAL CONFLICTS OF INTEREST Other Improper Business Practices 503.570-2 Contract clause. Insert the clause at 552.203-71, Restriction on Advertising, in solicitations and contracts...

Mullite-alumina functionally gradient ceramics

International Nuclear Information System (INIS)

Pena, P.; Bartolome, J.; Requena, J.; Moya, J.S.

1993-01-01

Cracks free mullite-alumina Functionally Gradient Ceramics (FGC) have been obtained by sequential slip casting of Mullite-alumina slurries with different mullite/alumina ratios. These slurries were prepared with 65 % solids content and viscosities ranging from 10 to 40 mPa.s. The presence of cracks perpendicular to the FGC layers have been attributed to residual stresses developed because of the mismatch in thermal expansion between layers. The microstructure of the different layers, and de residual stress value σ R in each layer was also determined. (orig.)

37 CFR 11.61 - Savings clause.

Science.gov (United States)

2010-07-01

... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Savings clause. 11.61 Section... Disciplinary Proceedings; Jurisdiction, Sanctions, Investigations, and Proceedings § 11.61 Savings clause. (a... subsequent to such effective date, if such conduct would continue to justify suspension or exclusion under...

48 CFR 732.111 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 732.111... CONTRACTING REQUIREMENTS CONTRACT FINANCING General 732.111 Contract clauses. (a) [Reserved] (b) USAID may... Agency-specific indefinite quantity contracts that are a combination of contract types. Rather than using...

Electron-irradiation-induced phase transformation in alumina

International Nuclear Information System (INIS)

Chen, C.L.; Arakawa, K.; Lee, J.-G.; Mori, H.

2010-01-01

In this study, electron-irradiation-induced phase transformations between alumina polymorphs were investigated by high-resolution transmission electron microscopy. It was found that the electron-irradiation-induced α → κ' phase transformation occurred in the alumina under 100 keV electron irradiation. It is likely that the knock-on collision between incident electrons and Al 3+ cations is responsible for the occurrence of electron-irradiation-induced phase transformation from α-alumina to κ'-alumina.

Transport properties of alumina nanofluids

International Nuclear Information System (INIS)

Wong, Kau-Fui Vincent; Kurma, Tarun

2008-01-01

Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 deg. C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m -1 K -1 was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 deg. C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were taken at various

48 CFR 811.404 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clause. 811.404... ACQUISITION PLANNING DESCRIBING AGENCY NEEDS Delivery or Performance Schedules 811.404 Contract clause. When delivery is required by or on a particular date for f.o.b. destination contracts, the contracting officer...

Esterification of Glycerol with Acetic Acid over Highly Active and Stable Alumina-based Catalysts: A Reaction Kinetics Study

OpenAIRE

Rane, S. A.; Pudi, S. M.; Biswas, P.

2016-01-01

The catalytic activity of Cu- or Ni monometallic and Cu-Ni bimetallic (Cu/Ni ratio = 3, 1, 0.33) catalysts supported on γ-Al2O3 and SO42–/γ-Al2O3 catalysts were evaluated for esterification of glycerol. The reactions were performed in a batch reactor under reflux at standard reaction conditions: temperature 110 °C, atmospheric pressure, glycerol to acetic acid molar ratio 1:9, and catalyst loading 0.25 g. The best catalytic activity was observed over 2 M SO42–/γ-Al2O3 catalyst, which showed t...

Synthesis of nano γ-alumina by the solvothermal technique

International Nuclear Information System (INIS)

Meor Yusoff Meor Sulaiman; Masliana Muslimin

2006-01-01

The paper describes work done on synthesis of γ-alumina by using the solvo thermal technique. Synthesis of γ-alumina involves the transition reactions of the aluminium hydroxide into alumina by a dehydroxylation process. As there are many forms of transition aluminas produced during this process, a x-ray diffraction (XRD) technique was used to identify γ-alumina and the other forms of alumina. After establishing the optimum conditions for the production of a single-phase γ-alumina, characteristic study on the product was performed. An important parameter in establishing nanosized powders is their crystallite size and analysis of the γ-alumina shows that it is a nanosized powder with a size of 28 nm. Other properties analysed include morphology, surface area and particle size. (Author)

Modification of sulphide catalysts for hydro-treatment by addition of fluorine; Modification de catalyseurs sulfure pour l'hydrotraitement par ajout de fluor

Energy Technology Data Exchange (ETDEWEB)

Fischer, L.

1999-12-15

Ni, Mo and NiMo sulphide catalysts supported on alumina were modified with fluorine in the range of 0.8 to 17 weight % F and tested in ortho-xylene hydrogenation under 60 bar total pressure and in presence of 1 bar H{sub 2}S. A positive effect of fluorine on Ni and NiMo catalytic activity was found. The tested catalysts were characterised by electronic microscopy and X-ray-photoelectron spectroscopy. The observed variations in dispersion and sulfidation degree of the active phase are not important enough to explain the good catalytic activity. The catalytic test was adapted in a way that allows a determination of electronic effects on sulphide catalysts under typical hydro-treating conditions. The product distribution in cis- and trans- 1,2-dimethyl-cyclohexane was found to be sensitive to the electronic state of the catalyst's active site. This was verified by addition of electron-donating NH{sub 3} as well as other evidences. According to this test, fluorine acts as an electron-donator on Ni and NiMo catalysts' active sites. A volcano curve of catalytic activity in function of electronic density is obtained for MoS{sub 2} based catalysts (Mo and NiMo), suggesting the existence of an optimum electronic density which would be achieved by introduction of about 6 weight % F into a NiMo catalyst. Characterization by infrared spectroscopy of adsorbed CO confirms the electron-donating effect of fluorine. Fluoridation tests of bulk catalysts permitted to exclude a bonding between fluorine and the active sulphide phase in absence of a support. It is suggested that electron-donating fluoride located on the surface of alumina, the interaction with nickel being of van-der-Waals type. (author)

48 CFR 3027.409 - Solicitation provisions and contract clauses.

Science.gov (United States)

2010-10-01

... containing the basic clause unless the HCA approves an exclusion. Additional non-conflicting alternates may... and contract clauses. 3027.409 Section 3027.409 Federal Acquisition Regulations System DEPARTMENT OF..., AND COPYRIGHTS Rights in Data and Copyrights 3027.409 Solicitation provisions and contract clauses...

Catalyst compositions useful for olefin isomerization and disproportionation

International Nuclear Information System (INIS)

Drake, C.A.

1987-01-01

A process is described for the double bond isomerization of an aliphatic olefinic hydrocarbon feed which comprises contacting the feed under isomerization conditions with a catalyst prepared by: (a) impregnating an alumina support having a surface area of at least 200 m/sup 2//g and a pore volume of at least 0.45 cm/sup 3//g with: 1 up to 20 wt. % of at least one magnesium compound convertible to the oxide, based on the weight of support and calculated as the metal; 0 up to 5 wt. % of at least one alkali metal compound convertible to the oxide, based on the weight of support and calculated as the metal; and 0 up to 5 wt. % of at least one zirconium compound convertible to the oxide, based on the weight of support and calculated as the metal; and (b) heating the alumina support impregnated in accordance with step (a) in an oxygen-containing atmosphere under conditions suitable to convert at least a portion of the magnesium, alkali metal, and zirconium compounds to the oxide form

48 CFR 870.111-3 - Contract clauses.

Science.gov (United States)

2010-10-01

... officer shall include the clause at 852.270-2, Bread and bakery products—quantities, in solicitations and contracts for bread and bakery products. (b) The contracting officer shall include the clause at 852.270-3...

Effect of Gas Flowrate on Nucleation Mechanism of MWCNTs for a Compound Catalyst

Directory of Open Access Journals (Sweden)

S. Shukrullah

2017-01-01

Full Text Available Activation of the catalyst particles during a CVD process can be anticipated from the carbon feeding rate. In this study, Fe2O3/Al2O3 catalyst was synthesized with uniformly dispersed iron over alumina support for onward production of multiwalled carbon nanotubes (MWCNTs in a fluidized bed chemical CVD reactor. The effect of the ethylene flowrate on catalytic activity of the compound catalyst and morphology of the as-grown MWCNTs was also investigated in this study. The dispersed active phases of the catalyst and optimized gas flowrate helped in improving the tube morphology and prevented the aggregation of the as-grown MWCNTs. The flowrates, below 100 sccm, did not provide sufficient reactants to interact with the catalyst for production of defect-free CNT structures. Above 100 sccm, concentration of the carbon precursor did not show notable influence on decomposition rate of the gas molecules. The most promising results on growth and structural properties of MWCNTs were gained at ethylene flowrate of 100 sccm. At this flowrate, the ratio of G and D intensity peaks (IG/ID was deliberated about 1.40, which indicates the growth of graphitic structures of MWCNTs.

The kinetics of the partial dehydration of gibbsite to activated alumina in a reactor for pneumatic transport

Directory of Open Access Journals (Sweden)

NADEZDA JOVANOVIC

2001-04-01

Full Text Available The dehidration kinetics of gibbsite to activated alumina was investigated at four different temperatures between 883 K and 943 K in a reactor for pneumatic transport in the dilute two phase flow regime. The first order kinetic behavior of this reactionwith respect to the water content of the solid material was proved and an activation energy of 66.5 kJ/mol was calculated. The effect of residence time on the water content is given and compared with theoretical calculations. The water content and other characteristics of the products depend on two main parameters, one is the short residence time and the other is the temperature of the dehydration of gibbsite. The short residence time of the gibbsite particles in a reactor for pneumatic transport prevents crystallization into new phases, as established from XRD analysis data. Reactive amorphous alumina powder, with a specific surface area of 250 m2/g, suitable as a precursor for catalyst supports is obtained.

Co-Processing of Jatropha-Derived Bio-Oil with Petroleum Distillates over Mesoporous CoMo and NiMo Sulfide Catalysts

Directory of Open Access Journals (Sweden)

Shih-Yuan Chen

2018-02-01

Full Text Available The co-processing of an unconventional type of Jatropha bio-oil with petroleum distillates over mesoporous alumina-supported CoMo and NiMo sulfide catalysts (denoted CoMo/γ-Al2O3 and NiMo/γ-Al2O3 was studied. Either a stainless-steel high-pressure batch-type reactor or an up-flow fixed-bed reaction system was used under severe reaction conditions (330–350 °C and 5–7 MPa, similar to the conditions of the conventional diesel hydrodesulfurization (HDS process. To understand the catalytic performance of the mesoporous sulfide catalysts for co-processing, we prepared two series of oil feedstocks. First, model diesel oils, consisting of hydrocarbons and model molecules with various heteroatoms (sulfur, oxygen, and nitrogen were used for the study of the reaction mechanisms. Secondly, low-grade oil feedstocks, which were prepared by dissolving of an unconventional type of Jatropha bio-oil (ca. 10 wt % in the petroleum distillates, were used to study the practical application of the catalysts. Surface characterization by gas sorption, spectroscopy, and electron microscopy indicated that the CoMo/γ-Al2O3 sulfide catalyst, which has a larger number of acidic sites and coordinatively unsaturated sites (CUS on the mesoporous alumina framework, was associated with small Co-incorporated MoS2-like slabs with high stacking numbers and many active sites at the edges and corners. In contrast, the NiMo/γ-Al2O3 sulfide catalyst, which had a lower number of acidic sites and CUS on mesoporous alumina framework, was associated with large Ni-incorporated MoS2-like slabs with smaller stacking numbers, yielding more active sites at the brims and corresponding to high hydrogenation (HYD activity. Concerning the catalytic performance, the mesoporous CoMo/γ-Al2O3 sulfide catalyst with large CUS number was highly active for the conventional diesel HDS process; unfortunately, it was deactivated when oxygen- and nitrogen-containing model molecules or Jatropha bio

48 CFR 552.252-6 - Authorized Deviations in Clauses.

Science.gov (United States)

2010-10-01

... published in the General Services Administration Acquisition Regulation (48 CFR chapter 5). (2) This... published in the General Services Administration Acquisition Regulation by the addition of “(DEVIATION (FAR... ADMINISTRATION CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions and Clauses 552...

48 CFR 925.901 - Omission of the audit clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Omission of the audit clause. 925.901 Section 925.901 Federal Acquisition Regulations System DEPARTMENT OF ENERGY SOCIOECONOMIC PROGRAMS FOREIGN ACQUISITION Additional Foreign Acquisition Clauses 925.901 Omission of the audit clause...

Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

KAUST Repository

Shuai, Danmeng; Choe, Jong Kwon; Shapley, John R.; Werth, Charles J.

2012-01-01

Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

KAUST Repository

Shuai, Danmeng

2012-03-06

Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

Modeling methanol transfer in the mesoporous catalyst for the methanol-to-olefins reaction by the time-fractional diffusion equation

Science.gov (United States)

Zhokh, Alexey A.; Strizhak, Peter E.

2018-04-01

The solutions of the time-fractional diffusion equation for the short and long times are obtained via an application of the asymptotic Green's functions. The derived solutions are applied to analysis of the methanol mass transfer through H-ZSM-5/alumina catalyst grain. It is demonstrated that the methanol transport in the catalysts pores may be described by the obtained solutions in a fairly good manner. The measured fractional exponent is equal to 1.20 ± 0.02 and reveals the super-diffusive regime of the methanol mass transfer. The presence of the anomalous transport may be caused by geometrical restrictions and the adsorption process on the internal surface of the catalyst grain's pores.

Flame spray synthesis of CoMo/Al2O3 hydrotreating catalysts

DEFF Research Database (Denmark)

Høj, Martin; Linde, Kasper; Hansen, Thomas Klint

2011-01-01

containing 16wt.% Mo (atomic ratio Co/Mo=1/3), which did not contain crystalline MoO3 and only small amounts of CoAl2O4. The hydrotreating activity was approximately 75% of that of commercial cobalt molybdenum catalysts prepared by wet impregnation of pre-shaped alumina extrudates. Since the commercial...... obtained consisted mostly of γ-Al2O3 with some CoAl2O4, as evidenced by X-ray diffraction (XRD) and UV–vis spectroscopy. Bulk MoO3 was not detected by XRD, except at the highest molybdenum content (32wt.%) and in the unsupported sample, indicating that molybdenum is well dispersed on the surface.......After activation by sulfidation the activity of the catalysts were measured for the three hydrotreating reactions hydrodesulfurization, hydrodenitrogenation and hydrogenation using a model oil containing dibenzothiophene, indole and naphthalene in n-heptane solution. The best catalyst was the FSP-produced material...

Effect of the platinum content on the microstructure and micropore size distribution of Pt/alumina-pillared clays.

Science.gov (United States)

Barrera-Vargas, M; Valencia-Rios, J; Vicente, M A; Korili, S A; Gil, A

2005-12-15

The aim of this work is to study the effect of the platinum content (0-1.8 wt % Pt) on the microstructure of an alumina-pillared clay. For this purpose, the nitrogen physisorption data at -196 degrees C, the micropore size distributions of the supported platinum catalysts, and the hydrogen chemisorption results at 30 degrees C have been analyzed and compared. The preparation of the catalysts has modified the textural properties of the Al-pillared clay support, giving rise to a loss of surface area and micropore volume. After reduction at 420 degrees C, the presence of dispersed metallic platinum with mean crystallite size in the 22-55 A range has been found by hydrogen adsorption. Comparison of all results reveals that the platinum species block the micropore entrances by steric hindrance to nitrogen access as the platinum content increases.

Fabrication of Ceramic Matrix Composite Tubes Using a Porous Mullite/Alumina Matrix and Alumina/Mullite Fiber

National Research Council Canada - National Science Library

Radsick, Timothy

2001-01-01

... or from inadequate oxide-based ones. A porous mullite/alumina matrix combined with alumina/mullite fiber reinforcement eliminates the need for an interface coating while producing a strong, tough and oxidation resistant composite...

Plasma-sprayed tantalum/alumina cermets

International Nuclear Information System (INIS)

Kramer, C.M.

1977-12-01

Cermets of tantalum and alumina were fabricated by plasma spraying, with the amount of alumina varied from 0 to 65 percent (by volume). Each of four compositions was then measured for tensile strength, elastic modulus, and coefficient of thermal expansion. In general, strength and strain to failure decreased with increasing alumina content: 62 MPa for 100 percent Ta to 19 MPa for 35 v percent Ta. A maximum of 0.1 percent strain was observed for the sprayed 100 percent Ta specimens. The coefficient of thermal expansion measured for the pure Ta was 6.2 (10 -6 )/K

Fabrication of asymmetric alumina membranes

International Nuclear Information System (INIS)

Firouzghalb, H.; Falamaki, C.

2010-01-01

The effect of SrO addition on the thermal stabilization of transition aluminas with the aim of producing membrane layers (supported and unsupported) has been investigated. Al 2 O 3 -x wt.% SrO composite powders (x = 1, 3, 5, 8) were synthesized by co-precipitation of the hydroxides from solutions of AlCl 3 and Sr(NO 3 ) 2 salts using NH 4 OH as a precipitating agent. Optimum SrO dopant concentration regarding the transition aluminas stabilization effect was determined to be 5 wt.% based on XRD analysis. STA analysis showed a 30 deg. C shift versus higher temperatures in the transformation of final transitional alumina (θ-Al 2 O 3 ) to stable alpha phase due to addition of 5 wt.% SrO. The mechanism of transition aluminas thermal stabilization as a result of SrO addition is thoroughly discussed. Unsupported alumina membranes were prepared by drying boehmite sols at 600, 800, 1000 and 1100 deg. C. The effect of calcination temperature on surface area, pore size distribution of unsupported membranes containing 5 wt.% SrO has been investigated. The microstructure of unsupported and supported membranes revealed quite different. Smaller grains in the supported layers were attributed to the interaction between support and membrane.

Electrode-Modified Zeolites - Electrode Microstructures Contained in and on a Heterogeneous Catalyst

Science.gov (United States)

1988-07-15

zeolite Type Y and Pt supported on gamma-alumina. The electrolytic response of zeolite-supported Pt in the absence of added electrolyte salt for water or...character of metals at sizes where’ bulk metallic properties may not be exhibited. Furthermore, electrolyses are now allowed using loadings of catalysts which...in water until the filtrate tested negatively for Cl with AgNO 3; PtY was then dried a- 135 C. Equilibrium exchnge occurs at these low weight

Topic extraction from adverbial clauses

Directory of Open Access Journals (Sweden)

Carlos Rubio Alcalá

2016-06-01

Full Text Available This paper offers new data to support findings about Topic extraction from adverbial clauses. Since such clauses are strong islands, they should not allow extraction of any kind, but we show here that if the appropriate conditions are met, Topics of the CLLD kind in Romance can move out of them. We propose that two conditions must be met for such movement to be possible: the first is that the adverbial clause must have undergone topicalisation in the first place; the second is that the adverbial clause is inherently topical from a semantic viewpoint. Contrast with other language families (Germanic, Quechua and Japanese is provided and the semantic implications of the proposal are briefly discussed. Keywords: topicalisation; Clitic Left Dislocation; syntactic islands; adverbial clauses Este artículo ofrece nuevos datos sobre la extracción de Tópicos desde oraciones subordinadas adverbiales. Dado que dichas oraciones son islas fuertes, no deberían permitir extracción de ningún tipo, pero mostramos que si se dan las condiciones apropiadas, los Tópicos del tipo CLLD en lenguas románicas pueden desplazarse fuera de ellas. Proponemos que se deben cumplir dos condiciones para que ese movimiento sea posible: la primera es que la propia subordinada adverbial se haya topicalizado en primer lugar; la segunda es que la subordinada adverbial sea inherentemente un Tópico desde el punto de vista semántico. Proporcionamos también algunos contrastes con otras familias lingüísticas (germánica, quechua y japonés y se discuten brevemente las implicaciones semánticas de la propuesta. Palabras clave: topicalización; dislocación a la izquierda con clítico; islas sintácticas; oraciones adverbiales

Strategy to Combine Clauses In Waijewa Dialect A Sumbanese Language

Directory of Open Access Journals (Sweden)

Ni Wayan Kasni

2012-07-01

Full Text Available Clause is defined as a grammatical unit consisting of the elements of subject (S and predicate (P, both with object (O and adverbial (A, and has the capability of being a sentence. Clauses can be categorized based on (i the core arguments, (ii  the presence or absence of negative words in predicate, (iii the categories of words or phrases that occupy predicate function, (iv  its capacity of being a sentence, (v  their functions in sentences. A clause can be combined in two ways, first using coordinate conjunction forming a coordinate construction, and second using subordinate conjunction forming a subordinate construction. This research attempted to analyze the strategy of combining clauses in Waijewa Dialect; a Sumbanese language. This research applied qualitative method in which the written data were collected from three key informants and four supporting informants from each district in Waijewa using four techniques namely; (1 observation, (2 structure-based interview, (3 documentation, and (4 triangulation. The collected data were analyzed using distributional method. The theory used to analyze the data was the language typology theory proposed by Dixon (1994 and 2010 and Comrie (1983. The result showed that in Waijewa dialect clauses could be divided into two; namely, the clauses having verbal predicates and the ones having nonverbal predicates. Waijewa dialect has clitic pronouns marking the arguments of the verbs. They showed nominative, accusative, and genitive cases. The coordinate constructions in BSDW could be categorized into two forms such as:  (1 syndetic (construction marked by conjunction and (2 asyndetic (without conjunction marker. The forms of subordinate clause in subordinate construction were divided into three; namely, (1 relative clause, (2 complementation clause, and (3 adjunct clause. Arguments A and S were relativized by gapping and attaching the prefix {a-} to the V and the relativization of the arguments O, E

Control of the γ-alumina to α-alumina phase transformation for an optimized alumina densification

Energy Technology Data Exchange (ETDEWEB)

Lamouri, S.; Hamidouche, M.; Bouaouadja, N.; Belhouchet, H.; Garnier, V.; Fantozzi, G.; Trelkat, J.F.

2017-07-01

In this work, we studied the aptitude to sintering green bodies using γ-Al2O3 transition alumina as raw powder. We focused on the influence of the heating rate on densification and microstructural evolution. Phase transformations from transition alumina γ→δ→θ→α-Al2O3 were studied by in situ X-rays diffraction from the ambient to 1200°C. XRD patterns revealed coexistence of various phase transformations during the heating cycle. DTA and dilatometry results showed that low heating rate leads to a significant reduction of the temperature of the α-Al2O3 alumina formation. Around 1190, 1217 and 1240°C were found when using 5, 10 and 20°C/min of heating rate, respectively. The activation energy for θ-Al2O3→α-Al2O3 transformation calculated by Kissinger and JMA equations using dilatometry method were 464.29 and 488.79kJ/mol, respectively and by DTA method were 450.72 and 475.49kJ/mol, respectively. In addition, the sintering of the green bodies with low heating rate promotes the rearrangement of the grains during θ-Al2O3→α-Al2O3 transformation, enhancing the relative density to 95% and preventing the development of a vermicular structure. (Author)

48 CFR 3447.7000 - Foreign travel clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Foreign travel clause. 3447.7000 Section 3447.7000 Federal Acquisition Regulations System DEPARTMENT OF EDUCATION ACQUISITION REGULATION CONTRACT MANAGEMENT TRANSPORTATION Foreign Travel 3447.7000 Foreign travel clause. The contracting...

A simple and efficient approach for synthesis of 1,4-dihydro-pyridines using nano-crystalline solid acid catalyst

Directory of Open Access Journals (Sweden)

A. Moatari

2013-09-01

Full Text Available A simple highly versatile and efficient synthesis of various 1,4-dihydropyridines in the condensation of aromatic aldehydes with β-dicarbonyl compounds and ammonium acetate in the presence of nano-sulfated zirconia, nano-structured ZnO, nano-γ-alumina and nano-ZSM-5 zeolites, as catalyst in the ethanol at moderate temperature is presented. The advantages of method are short reaction times and milder conditions and easy work-up. The catalysts can be recovered for the subsequent reactions and reused without any appreciable loss of efficiency.DOI: http://dx.doi.org/10.4314/bcse.v27i3.12

Catalysis mechanism of Pd-promoted γ-alumina in the thermal decomposition of methane to hydrogen: A density functional theory study

Energy Technology Data Exchange (ETDEWEB)

Salam, M. Abdus; Abdullah, Bawadi, E-mail: bawadi_abdullah@utp.edu.my

2017-02-15

Thermo-catalytic methane decomposition to elemental hydrogen mechanism in transitional metals (Pd, Ni & Mo) promoted Al{sub 2}O{sub 3} (001) catalyst have been studied using the density functional theory (DFT). Decomposition reactions are spontaneous and favourable above 775 K for all promoter. Pd-promoted Al{sub 2}O{sub 3} (001) catalyst demonstrates a breakthrough decomposition activity in hydrogen production as compared to Ni− and Mo-promoted Al{sub 2}O{sub 3} (001) catalysts. The activation energy (E{sub a}) range of the catalysis for Pd promoted Al{sub 2}O{sub 3} (001) catalysts is 0.003–0.34 eV. Whereas, Ni and Mo promoted Al{sub 2}O{sub 3} (001) catalysts display activation energy E{sub a} in the range of 0.63–1.15 eV and 0.04–5.98 eV, respectively. Pd-promoted catalyst also shows a higher adsorption energy (−0.68 eV) and reactivity than that of Ni and Mo promoted Al{sub 2}O{sub 3} (001) catalysts. The rates of successive decomposition of methane are found to be 16.15 × 10{sup 12}, 15.95 × 10{sup 12} and 16.09 × 10{sup 12} s{sup −1} for the promoter of Pd, Ni and Mo, respectively. Pd promoted Al{sub 2}O{sub 3} (001) catalyst reduces the methane decomposition temperature (775 K) and deactivation rate significantly. The catalytic conditions and catalyst is promising in producing hydrogen to support hydrogen economy. - Highlights: • Transition metals (Pd, Ni & Mo) promoted γ-alumina catalysts are designed successfully. • Pd-promoted catalyst showed breakthrough activity in methane decomposition to hydrogen. • DFT study explored the catalysis mechanism of methane decomposition at atomic level. • Pd-promoted catalyst reduced temperature and activation barrier of methane decomposition reaction significantly.

Catalysis mechanism of Pd-promoted γ-alumina in the thermal decomposition of methane to hydrogen: A density functional theory study

International Nuclear Information System (INIS)

Salam, M. Abdus; Abdullah, Bawadi

2017-01-01

Thermo-catalytic methane decomposition to elemental hydrogen mechanism in transitional metals (Pd, Ni & Mo) promoted Al_2O_3 (001) catalyst have been studied using the density functional theory (DFT). Decomposition reactions are spontaneous and favourable above 775 K for all promoter. Pd-promoted Al_2O_3 (001) catalyst demonstrates a breakthrough decomposition activity in hydrogen production as compared to Ni− and Mo-promoted Al_2O_3 (001) catalysts. The activation energy (E_a) range of the catalysis for Pd promoted Al_2O_3 (001) catalysts is 0.003–0.34 eV. Whereas, Ni and Mo promoted Al_2O_3 (001) catalysts display activation energy E_a in the range of 0.63–1.15 eV and 0.04–5.98 eV, respectively. Pd-promoted catalyst also shows a higher adsorption energy (−0.68 eV) and reactivity than that of Ni and Mo promoted Al_2O_3 (001) catalysts. The rates of successive decomposition of methane are found to be 16.15 × 10"1"2, 15.95 × 10"1"2 and 16.09 × 10"1"2 s"−"1 for the promoter of Pd, Ni and Mo, respectively. Pd promoted Al_2O_3 (001) catalyst reduces the methane decomposition temperature (775 K) and deactivation rate significantly. The catalytic conditions and catalyst is promising in producing hydrogen to support hydrogen economy. - Highlights: • Transition metals (Pd, Ni & Mo) promoted γ-alumina catalysts are designed successfully. • Pd-promoted catalyst showed breakthrough activity in methane decomposition to hydrogen. • DFT study explored the catalysis mechanism of methane decomposition at atomic level. • Pd-promoted catalyst reduced temperature and activation barrier of methane decomposition reaction significantly.

48 CFR 225.7403-2 - Contract clause.

Science.gov (United States)

2010-10-01

... performance or travel outside the United States, except for contracts with— (a) Foreign governments; (b..., DEPARTMENT OF DEFENSE SOCIOECONOMIC PROGRAMS FOREIGN ACQUISITION Defense Contractors Outside the United States 225.7403-2 Contract clause. Use the clause at 252.225-7043, Antiterrorism/Force Protection Policy...

48 CFR 2011.104-70 - NRC Clauses.

Science.gov (United States)

2010-10-01

... ACQUISITION PLANNING DESCRIBING AGENCY NEEDS Delivery or Performance Schedules-Contract Clauses 2011.104-70...) The contracting officer shall insert the clause at 2052.211-72 Financial Status Report, in applicable cost reimbursement solicitations and contracts when detailed assessment of costs is warranted and a...

Heterogeneous catalysis in the liquid-phase oxidation of olefins--3. The activity of supported vanadium-chromium binary oxide catalyst for the oxidation of cyclohexene

Energy Technology Data Exchange (ETDEWEB)

Takehira, K; Hayakawa, T; Ishikawa, T

1979-03-01

The activity of supported vanadium-chromium binary oxide catalyst for the oxidation of cyclohexene to 1-cyclohexenyl hydroperoxide, 2-cyclohexene-1-one, 2-cyclohexene-1-ol, and cyclohexene oxide was due to the interaction between the metal oxides and the carriers. The oxidation reaction was carried out in benzene at 60/sup 0/C for four hours with the binary oxide supported on (GAMMA)-alumina or silica; three series of catalysts were prepared by combining the vanadium and chromium oxide components with alumina hydrate or silica sol by a kneading method. The silica-supported catalysts had the greatest activity, the highest being the V/sub 2/O/sub 5//SiO/sub 2/ system, which lost its activity quickly during the reaction. This was followed in activity by the Cr/sub 2/O/sub 3//SiO/sub 2/ system, containing the chromium(V) species. The Cr/sub 2/O/sub 3//Al/sub 2/O/sub 3/ system also had high activity and the chromium(V) species. The vanadium and chromium metal ions are probably coordinated tetrahedrally on the support, and these complexes catalyze cyclohexene autoxidation by decomposing 1-cyclohexenyl hydroperoxide.

High alumina refractories

International Nuclear Information System (INIS)

Simao, L.C.; Lopes, A.B.; Galvao Filho, N.B.; Souza, R.B. de

1989-01-01

High alumina refractories with 92 to 96.5% Al 2 O 3 were produced using brown and white fused as aggregate. Those refractories present only alumina-α and mullite as crystalline mineralogical phase. Other physical and chemical characteristics are similar to the ones found in refractories produced in Brazil, Japan and U.S.A. The most important physical and chemical tests used for the characterization of the raw materials and refractories, complemented by those realized at high temperatures, plus X-ray Difractometry and optical microscopy are presented, besides the refractory formulation and main parameters of production [pt

Improvement of sulfur resistance of Pd/Ce-Zr-Al-O catalysts for CO oxidation

Science.gov (United States)

Shin, Haebin; Baek, Minsung; Ro, Youngsoo; Song, Changyeol; Lee, Kwan-Young; Song, In Kyu

2018-01-01

Two kinds of mesoporous ceria-zirconia-alumina supports were prepared by a single-step epoxide-driven sol-gel method (SGCZA) and by a co-precipitation method (PCZA). Palladium catalysts supported on these materials were then prepared by a wet impregnation method (Pd/SGCZA and Pd/PCZA). The prepared catalysts were applied to the CO oxidation reaction before and after sulfur aging. XRD and N2 adsorption-desorption analyses revealed that these two catalysts retained different physicochemical properties. Pd/SGCZA had higher surface area and larger pore volume than Pd/PCZA before and after sulfur aging. TPR (Temperature-programmed reduction), CO chemisorption, FT-IR, and XPS analyses showed that the catalysts were differently influenced by sulfur species. Pd/SGCZA formed less sulfate and retained higher palladium dispersion than Pd/PCZA after sulfur aging. In the CO oxidation, Pd/PCZA showed better activity than Pd/SGCZA before sulfur aging. However, Pd/SGCZA showed higher CO conversion than Pd/PCZA after sulfur aging. We concluded that Pd/SGCZA was less poisoned by sulfur species than Pd/PCZA.

Rights granted in the habendum clause

International Nuclear Information System (INIS)

Burgess, P.W.

1998-01-01

The habendum clause sets out the conditions for the continuance of a petroleum or natural gas lease during the primary term and during the events or circumstances which will continue the lease beyond the primary term. This paper describes the rights granted in the habendum clause. Typical older forms of freehold leases are compared with the model lease form and with the 1991 form of the Canadian Association of Petroleum Landmen (CAPL) Petroleum and Natural Gas lease. These comparisons were made in an effort to analyse the changes in the nature of the rights granted in the habendum clause. The most significant change is that the 1991 CAPL lease form avoids the 'unless' pitfalls of older forms by creating firstly the 'drill or pay' form of habendum clause, and by introducing the alternatives of paying either a lump sum one time rental or a periodic rental payment. The effect of these changes is that failure to make timely payments does not result in automatic termination of the lease, but rather one which must be made subject of a default notice by the lessor to the lessee.12 refs

48 CFR 1852.301 - Solicitation provisions and contract clauses (Matrix).

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Solicitation provisions and contract clauses (Matrix). 1852.301 Section 1852.301 Federal Acquisition Regulations System NATIONAL... and Clause Matrix 1852.301 Solicitation provisions and contract clauses (Matrix). ...

48 CFR 1836.570 - NASA solicitation provisions and contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true NASA solicitation provisions and contract clause. 1836.570 Section 1836.570 Federal Acquisition Regulations System NATIONAL... CONTRACTS Contract Clauses 1836.570 NASA solicitation provisions and contract clause. (a) The contracting...

Obtaining aluminas from the thermal decomposition of their different precursors: An {sup 27}Al MAS NMR and X-ray powder diffraction studies

Energy Technology Data Exchange (ETDEWEB)

Chagas, L.H.; De Carvalho, G.S.G. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); San Gil, R.A.S. [Universidade Federal do Rio de Janeiro, Instituto de Química, 21949-900 Rio de Janeiro, RJ (Brazil); Chiaro, S.S.X. [PETROBRAS-CENPES, 21941-915 Rio de Janeiro, RJ (Brazil); Leitão, A.A. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); Diniz, R., E-mail: renata.diniz@ufjf.edu.br [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil)

2014-01-01

Graphical abstract: - Highlights: • We synthesized three precursors of alumina from different methods. • The calcination of the precursors generated several alumina polymorphs. • XRD and NMR were used for structural investigation of the polymorphs. • The synthesis route determines the structural and textural properties of the solids. - Abstract: A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. The characteristics of the four precursors were investigated by thermal, vibrational and X-ray powder diffraction (XRD) analysis. Additionally, the nuclear magnetic resonance, with magic angle spinning ({sup 27}Al MAS NMR), was used to verify the coordination of aluminum cations. Each precursor was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and {sup 27}Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al{sub 2}O{sub 3} phase, which in addition to structural investigation was subjected to textural analysis. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties, which in turn can significantly influence the performance of a supported catalyst.

Characterization and sintering of niobium-ATR alumina

International Nuclear Information System (INIS)

Sibuya, N.H.; Iwasaki, H.; Suzuki, C.K.; Pinatti, D.G.

1987-01-01

In the niobium aluminothermy a slag is produced, composed mostly of alumina and other compounds such as niobium oxide and silica. The phase composition of this ATR alumina was characterized by X-ray powder diffractometry, and afterwards this alumina was subjected to leaching processes. It was noticed that the original content of 70% α-alumina in slag rose to 95% after the calcination. ATR alumina (leached and calcined, and without any treatment) was used to make pressed bodies which were fired in air at 1200 to 1400 0 C for 1 to 10,5 hours; and in vacuum at 1550 to 1800$0C for 2 hours. Characterization was done by density measurements, X-ray diffractometry and ultrasonic analysis. Ultrasonic analysis of some vacuum fired bodies showed londitudinal velocities close to the value found in literature. Correlation of several techniques measurements disclosed the niobium oxide interference in sintering. (Author) [pt

Obtaining and characterization catalyst Ki/Al_2O_3 by physical dispersion process via wet

International Nuclear Information System (INIS)

Silva, M.C. da; Dantas, J.; Costa, A.C.F.M.; Costa, N.C.O.; Freitas, N.L. de

2014-01-01

The aim of this study is the Obtention and characterization of catalysts being supported alumina impregnated with KI by physical dispersion in wet via attritor mill in periods of 30 and 60 minutes. Before and after impregnation the catalysts were characterized by XRD, X ray fluorescence, particle size distribution, textural analysis (BET). The results show the presence of the stable crystalline phase Al_2O_3 in all samples after impregnation and the second phase formed from KI and K_2O. There was a decrease in the agglomerates incorporated with the potassium due to the milling process. It was observed that the highest specific surface area was obtained by the impregnated sample into a 60 min. (author)

The validity of knock-for-knock clauses in comparative perspective

DEFF Research Database (Denmark)

Cavaleri, Sylvie Cécile

This article discusses the validity of so-called knock-for-knock clauses, by which parties to offshore oil and gas or maritime contracts agree that each of them will cover its own losses regardless of who caused them. The issue of validity of such clauses and of the liability exclusions they cont......This article discusses the validity of so-called knock-for-knock clauses, by which parties to offshore oil and gas or maritime contracts agree that each of them will cover its own losses regardless of who caused them. The issue of validity of such clauses and of the liability exclusions...... criteria used to promote or dismiss knock-for-knock clauses in case law and academic literature, the article reaches the conclusion that the question of whether knock-for-knock clauses should be held valid depends on whose interests are being considered, and that further research is warranted...

48 CFR 916.203-4 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 916.203-4 Section 916.203-4 Federal Acquisition Regulations System DEPARTMENT OF ENERGY CONTRACTING METHODS AND CONTRACT TYPES TYPES OF CONTRACTS Fixed-Price Contracts 916.203-4 Contract clauses. (d)(2) The...

48 CFR 1535.007-70 - Contract clauses.

Science.gov (United States)

2010-10-01

... clause at 1552.235-70, Screening Business Information for Claims of Confidentiality, in contracts when... proprietary or confidential by the business that has the right to the information. (b) The Contracting Officer shall insert the clause at 48 CFR 1552.235-71, Treatment of Confidential Business Information, in...

48 CFR 227.7102-3 - Contract clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Contract clause. 227.7102..., DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS Rights in Technical Data 227.7102-3 Contract clause. (a)(1) Except as provided in paragraph (b) of this subsection, use the...

Recovery of homogeneous polyoxometallate catalysts from aqueous and organic media by a mesoporous ceramic membrane without loss of catalytic activity

NARCIS (Netherlands)

Roy Chowdhury, S.; Roy Chowdhury, Sankhanilay; Witte, Peter T.; Blank, David H.A.; Alsters, Paul L.; ten Elshof, Johan E.

2006-01-01

The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous γ-alumina membranes is reported. The recovery of Q12[WZn3(ZnW9O34)2] (Q=[MeN(n-C8H17)3]+) from toluene-based media was quantitative within

48 CFR 52.301 - Solicitation provisions and contract clauses (Matrix).

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Solicitation provisions and contract clauses (Matrix). 52.301 Section 52.301 Federal Acquisition Regulations System FEDERAL... and Clause Matrix 52.301 Solicitation provisions and contract clauses (Matrix). Note: The FAR matrix...

An anodic alumina supported Ni-Pt bimetallic plate-type catalysts for multi-reforming of methane, kerosene and ethanol

KAUST Repository

Zhou, Lu; Guo, Yu; Kameyama, Hideo; Basset, Jean-Marie

2014-01-01

. The prepared Ni-Pt catalyst showed excellent performance during steam reforming of methane, kerosene and ethanol under both 3000 h stationary and 500-time daily start-up and shut-down operation modes. Self-activation ability of this catalyst was evidenced

48 CFR 211.274-6 - Contract clauses.

Science.gov (United States)

2010-10-01

... Valuation, in solicitations and contracts that— (i) Require item identification or valuation, or both, in... the clause at— (i) FAR 52.245-1, Government Property; or (ii) FAR 52.245-2, Government Property...— (1) Contain the clause at 252.211-7003, Item Identification and Valuation; and (2) Require the...

48 CFR 970.2303-3 - Contract clauses.

Science.gov (United States)

2010-10-01

... facility, the clause at 48 CFR 970.5223-1, Integration of Environment, Safety and Health into Work Planning..., Renewable Energy Technologies, Occupational Safety and Drug-Free Work Place 970.2303-3 Contract clauses. (a) When work under management and operating contracts and subcontracts thereunder is to be performed at a...

Recovery of Platinum Group Metals from Spent Catalysts Using Iron Chloride Vapor Treatment

Science.gov (United States)

Taninouchi, Yu-ki; Okabe, Toru H.

2018-05-01

The recovery of platinum group metals (PGMs) from spent automobile catalysts is a difficult process because of their relatively low contents in the scrap. In this study, to improve the efficiency of the existing recycling techniques, a novel physical concentration method involving treatment with FeCl2 vapor has been examined. The reactions occurring between typical catalyst components and FeCl2 vapor are discussed from the thermodynamic point of view, and the validity of the proposed technique was experimentally verified. The obtained results indicate that the vapor treatment at around 1200 K (927 °C) can effectively alloy PGMs (Pt, Pd, and Rh) with Fe, resulting in the formation of a ferromagnetic alloy. It was also confirmed that cordierite and alumina (the major catalyst components) remained unreacted after the vapor treatment, while ceria species were converted into oxychlorides. The samples simulating the automobile catalyst were also subjected to magnetic separation after the treatment with FeCl2 vapor; as a result, PGMs were successfully extracted and concentrated in the form of a magnetic powder. Thus, the FeCl2 vapor treatment followed by magnetic separation can be utilized for recovering PGMs directly from spent catalysts as an effective pretreatment for the currently used recycling methods.

Processing Relative Clause Extractions in Swedish

OpenAIRE

Tutunjian, Damon; Heinat, Fredrik; Klingvall, Eva; Wiklund, Anna-Lena

2017-01-01

Relative clauses are considered strong islands for extraction across languages. Swedish comprises a well-known exception, allegedly allowing extraction from relative clauses (RCE), raising the possibility that island constraints may be subject to “deep variation” between languages. One alternative is that such exceptions are only illusory and represent “surface variation” attributable to independently motivated syntactic properties. Yet, to date, no surface account has proven tenable for Swed...

Investigating the property profile of polyamide-alumina nanocomposite materials

International Nuclear Information System (INIS)

Sarwar, Muhammad Ilyas; Zulfiqar, Sonia; Ahmad, Zahoor

2009-01-01

Transparent sol-gel-derived nanocomposites were prepared by incorporating an alumina network into a polyamide matrix. Different amounts of aluminum butoxide were hydrolyzed and condensed to produce the alumina network. Thin composite films were characterized in terms of their optical, morphological, mechanical and thermomechanical properties. Tensile modulus, stress at both yield and break points, improved for alumina loadings of 5-10 wt.%. The glass transition temperature increased to 140 o C for nanocomposites containing 15 wt.% alumina. Scanning electron microscopy investigations indicated a uniform distribution of alumina in the polyamide matrix.

Enhanced activity and stability of copper oxide/γ-alumina catalyst in catalytic wet-air oxidation: Critical roles of cerium incorporation

Science.gov (United States)

Zhang, Yongli; Zhou, Yanbo; Peng, Chao; Shi, Junjun; Wang, Qingyu; He, Lingfeng; Shi, Liang

2018-04-01

By successive impregnation method, the Ce-modified Cu-O/γ-Al2O3 catalyst was prepared and characterized using nitrogen adsorption-desorption, scanning electron microscopy energy dispersive X-ray analysis (SEM-EDS), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, and H2-Temperature programming reduction (H2-TPR). In catalytic wet-air oxidation (CWAO) process for the printing and dyeing wastewater (PDW), the effects of Ce addition on performance, mechanism and kinetics of the catalyst were investigated. The Ce addition increases the Brunauer-Emmett-Teller (BET) surface area and pore volume of the catalyst and makes the active components uniformly distributed on the catalyst surface. Formation of a stable CuAl2O4 solid solution by anchoring Cu onto the γ-Al2O3 crystal lattice leads to a significant decrease in metal leaching of the Ce-modified catalyst. The proportion of lattice oxygen in the catalyst substantially increases and the apparent activation energy of Cu-O/γ-Al2O3 catalyst decreases owing to Ce addition. Therefore, the catalytic activity and stability of the Ce-modified catalyst are considerably improved. The scavengers experiments identify the active species existed in the CWAO reaction system, with the order of reactivity: h+ > O2•- > H2O2 > HO•. This novel Cu-Ce-O/γ-Al2O3 catalyst has great potential in applications for treatment of concentrated organic wastewater due to its superior catalytic activity and improved stability.

Development of a wetproofed catalyst recombiner for removal of airborne tritium

International Nuclear Information System (INIS)

Chuang, K.T.; Quaiattini, R.J.; Thatcher, D.R.P.; Puissant, L.J.

1985-01-01

For cleanup of airborne tritium at tritium handling facilities, it is generally agreed that the most reliable method is to convert the tritium in a recombiner into water vapor followed by adsorption of the vapor in a molecular sieve drier. Decontamination factors of 10 3 to 10 6 have been reported. Wetproofed catalysts developed at Chalk River Nuclear Laboratories have been shown to maintain their activities when exposed to liquid water or air at 100% relative humidity. When a wetproofed catalyst recombiner is used, operation can be carried out at room temperatures thus greatly simplifying the system. Two catalysts, Pt/carbon and Pt/silica, were prepared for this study. The activity of Pt/carbon was measured with hydrogen and found to be comparable to the published results for conventional Pt/alumina catalysts at similar conditions. Experiments were carried out for the following range of operating conditions: flows from 0.3 to 3.0 m/s, pressure from 100 to 500 kPa. Tritium was added to the air stream at 1-5 MBq.m -3 (30-140 μCi.m -3 ). No significant isotope and/or pressure effects were observed. To date lifetime data of greater than four months have been obtained

The characterization of thin platinum films on alumina

International Nuclear Information System (INIS)

Altman, E.I.; Gorte, R.J.

1987-01-01

Industrial metal catalysts are usually in the form of small metal particles supported on a porous oxide. The typical size of these metal particles ranges between 1.0 and 10.0 nm and it is well known that the particle size and the oxide substrate can affect the catalytic properties of the metal for some important reactions. Previous work with adsorption on small particles has indicated that desorption temperatures and the ability to dissociate CO can also be affected by the particle size. To further investigate these size and substrate effects, the authors have examined the adsorption properties of several simple gases on small Pt particles supported on alumina using temperature programmed desorption (TPD). The author show that the desorption curves for CO, H/sub 2/, and NO on these particles are very similar to curves measured on single crystals. The details of sample preparation and characterization have been described previously. Samples were prepared by vapor depositing Pt onto an alumina substrate which was formed by exposing an Al film to O/sub 2/. Auger electron spectroscopy was used to monitor surface cleanliness and to characterize the growth of the Pt on the substrate. As reported previously, the Pt grew in a layer-by-layer manner at both 90K and 300K. This film aggregated into clusters when the sample was heated above 650K and the average size of these particles could be determined from the saturation coverage of CO and from the quantity of metal deposited, as measured using a film thickness monitor. All adsorption measurements reported in this paper were made on samples heated above 650K

A Logical Deduction Based Clause Learning Algorithm for Boolean Satisfiability Problems

Directory of Open Access Journals (Sweden)

Qingshan Chen

2017-01-01

Full Text Available Clause learning is the key component of modern SAT solvers, while conflict analysis based on the implication graph is the mainstream technology to generate the learnt clauses. Whenever a clause in the clause database is falsified by the current variable assignments, the SAT solver will try to analyze the reason by using different cuts (i.e., the Unique Implication Points on the implication graph. Those schemes reflect only the conflict on the current search subspace, does not reflect the inherent conflict directly involved in the rest space. In this paper, we propose a new advanced clause learning algorithm based on the conflict analysis and the logical deduction, which reconstructs a linear logical deduction by analyzing the relationship of different decision variables between the backjumping level and the current decision level. The logical deduction result is then added into the clause database as a newly learnt clause. The resulting implementation in Minisat improves the state-of-the-art performance in SAT solving.

21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white, odorless...

Preconcentration and Determination of Antimony in Drinking Water Bottled by Modified Nano-Alumina

Directory of Open Access Journals (Sweden)

M Mohammad Zakizade

2016-01-01

Full Text Available Abstract Introduction: Antimony trioxide (Sb2O3 has been utilized as a catalyst in polyethylene terephtalate (PET production, and the studies conducted on the bottled water has demonstrated that antimony can be leached from PET bottles into drinking water. Methods: In this study, a simple method was applied in order to determine the trace amount of antimony in bottled drinking water based on preconcentration /solid phase extraction. The nano alumina modified with Schiff base ligand was used in regard with Sb preconcentration. The experiments were performed in a continuous system and HCI was used as eluent of Sb ion. Several chemical and flow variables were optimized for a quantitative preconcentration and determination of Sb ion. The atomic absorption spectroscopy was used to determine Sb ion concentration. In order to study the keeping conditions on the leaching of Sb ion from PET plastic, drinking water bottles were kept in different conditions(room temperature, sunny light and -18˚C. Results: The calibration graph was linear in the range of 0.5 to 15.0 ppm Sb with detection limit of 0.055 ppm. The flow rate of sample was optimized in range of 1.0-9.0 mLmin-1 and Sb ion can be quantitatively eluted at 90 Vsample: Veluent retio. Conclusion: The study results revealed that the modified nano alumina is an effective sorbent in regard with absorbing Sb ion from water and HCI 1M can be used as an appropriate eluent. Maximum leaching of Sb ion is observed when the bottled drinking water was exposed to the sun light. Keywords: Antimony; Bottled drinking water; Modified alumina; Preconcentration

48 CFR 922.103-5 - Contract clauses.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Contract clauses. 922.103... PROGRAMS APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITION Basic Labor Policies 922.103-5 Contract clauses. In accordance with FAR 22.101-1(e) and FAR 22.103-5, the contracting officer shall insert the...

Inversion in Copular Clauses and Its Consequences

Science.gov (United States)

Selvanathan, Nagarajan

2016-01-01

In this dissertation, I investigate specificational copular clauses (Higgins 1973). My aim is to not only propose an analysis for how such specificational copular clauses are derived but also to use such constructions as a testing ground for evaluating and/ or revising different aspects of linguistic theory. The language I primarily use towards…

48 CFR 1649.101-71 - FEHBP termination for convenience clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true FEHBP termination for convenience clause. 1649.101-71 Section 1649.101-71 Federal Acquisition Regulations System OFFICE OF PERSONNEL... CONTRACTS General Principles 1649.101-71 FEHBP termination for convenience clause. The clause set forth in...

Semantic Bias in the Acquisition of Relative Clauses in Japanese

Science.gov (United States)

Ozeki, Hiromi; Shirai, Yasuhiro

2010-01-01

This study analyzes the acquisition of relative clauses in Japanese to determine the semantic and functional characteristics of children's relative clauses in spontaneous speech. Longitudinal data from five Japanese children are analyzed and compared with English data (Diessel & Tomasello, 2000). The results show that the relative clauses produced…

Development of porous structure simulator for multi-scale simulation of irregular porous catalysts

International Nuclear Information System (INIS)

Koyama, Michihisa; Suzuki, Ai; Sahnoun, Riadh; Tsuboi, Hideyuki; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Del Carpio, Carlos A.; Miyamoto, Akira

2008-01-01

Efficient development of highly functional porous materials, used as catalysts in the automobile industry, demands a meticulous knowledge of the nano-scale interface at the electronic and atomistic scale. However, it is often difficult to correlate the microscopic interfacial interactions with macroscopic characteristics of the materials; for instance, the interaction between a precious metal and its support oxide with long-term sintering properties of the catalyst. Multi-scale computational chemistry approaches can contribute to bridge the gap between micro- and macroscopic characteristics of these materials; however this type of multi-scale simulations has been difficult to apply especially to porous materials. To overcome this problem, we have developed a novel mesoscopic approach based on a porous structure simulator. This simulator can construct automatically irregular porous structures on a computer, enabling simulations with complex meso-scale structures. Moreover, in this work we have developed a new method to simulate long-term sintering properties of metal particles on porous catalysts. Finally, we have applied the method to the simulation of sintering properties of Pt on alumina support. This newly developed method has enabled us to propose a multi-scale simulation approach for porous catalysts

Superhydrophilicity of novel anodic alumina nanofibers films and their formation mechanism

Science.gov (United States)

Peng, Rong; Yang, Wulin; Fu, Licai; Zhu, Jiajun; Li, Deyi; Zhou, Lingping

2017-06-01

A novel anodic alumina nanofibers structure, which is different from the traditional porous anodic structure, has been quickly fabricated via anodizing in a new electrolyte, pyrophosphoric acid. The effects of the solution concentration and the anodizing time on the formation of the anodic alumina nanofibers were analyzed. The results show that the nanostructure of anodic alumina can change to the nanofiber oxide from the porous oxide by increasing the solution concentration. Prolonging the anodizing time is beneficial to obtain alumina nanofibers at high solution concentration. Growth behavior of the alumina nanofibers was also discussed by scanning electron microscopy observations. Owing to the unique hexagonal structure of anodic alumina as well as the preferential chemical dissolution between the porous anodic alumina and the anodic alumina nanotips, the slightly soluble anodic alumina nanotips could form novel alumina nanofibers during anodizing. The results show that the nanofibers-covered aluminum surface exhibits superhydrophilic property, with a near-zero water contact angle. Such alumina nanofibers with superhydrophilic property could be used for various potential applications.

The Role of the Penalty Clause in Business

Directory of Open Access Journals (Sweden)

Maria Stegariu

2016-07-01

Full Text Available The interest in this topic is determined, on one hand, by the way of interpreting the provisions which regulate the contractual liability in general and of those regarding the penalty clause in particular, and, on the other hand, by the formulation of certain proposals de lege ferenda. By stipulating the penalty clause, the law seeks to execute the contractual obligations, and not to collect penalties. The legal base of the ancillary character of the penalty clause is article 1538, paragraph 3 of the Civil Code.    

Effects of Etching Time and NaOH Concentration on the Production of Alumina Nanowires Using Porous Anodic Alumina Template

Science.gov (United States)

Sadeghpour-Motlagh, M.; Mokhtari-Zonouzi, K.; Aghajani, H.; Kakroudi, M. Ghassemi

2014-06-01

In this work, two-step anodizing of commercial aluminum foil in acid oxalic solution was applied for producing alumina film. Then the anodic alumina film was etched in sodium hydroxide (NaOH) solution resulting dense and aligned alumina nanowires. This procedure leads to splitting of alumina nanotubes. Subsequently nanowires are produced. The effects of NaOH solution concentration (0.2-1 mol/L) and etching time (60-300 s) at constant temperature on characteristic of nanotubes and produced nanowires were investigated using scanning electron microscopy. The results show that an increase in NaOH solution concentration increases the rate of nanowires production and in turn the manipulation process will be more specific.

Nominalized clauses, clausal arguments and agreement

OpenAIRE

Picallo, M. Carme

2001-01-01

Strict minimalist assumptions require adopting the hypothesis that argument clauses and nominalized clauses are assigned Phi features. The data examined suggest that the interpretable Phi content of these arguments is specified as [-P, -N, -G]. We conclude that all arguments (of the clausal or of the nominal types) are subject to the operation Agree with a functional category. All arguments behave alike as far as abstract computational operations is concerned. The computational component is b...

Improved Catalysts for Heavy Oil Upgrading Based on Zeolite Y Nanoparticles Encapsulated Stable Nanoporous Host

Energy Technology Data Exchange (ETDEWEB)

Conrad Ingram; Mark Mitchell

2006-09-30

The addition of hydrothermally-aged zeolite Y precursor to an SBA-15 synthesis mixture under a mildly acidic condition resulted in the formation of mesoporous aluminosilicate catalyst, Al-SBA-15, containing strong Broensted acid sites and aluminum (Al) stabilized in a totally tetrahedral coordination. The physicochemical characteristics of the catalyst varied as a function of the synthesis conditions. The catalyst possessed surface areas ranging between 690 and 850 m{sup 2}/g, pore sizes ranging from 5.6 to 7.5 nm, and pore volumes up 1.03 cm{sup 3}, which were comparable to the parent SBA-15 synthesized under similar conditions. Two wt% Al was present in the catalyst that was obtained from the reaction mixture that contained the highest Al content. The Al remained stable in totally tetrahedral coordination after calcination at 550 C. The Al-SBA-15 mesoporous catalyst showed significant catalytic activity for cumene dealkylation, and the activity increased as the amount of zeolite precursor added to the SBA-15 mixture was increased. In preparation for the final phase of the project, the catalyst was embedded into psuedoboemite alumina (catapal B) matrix and then formed into pellets. In the final phase of the project, the pelletized catalyst will be evaluated for the conversion of heavy petroleum feedstocks to naphtha and middle distillates.

Linear free energy relationships in heterogeneous catalysis--13. The dehydration of aliphatic alcohols over silica-alumina. [N-butyl alcohol, sec. -butyl or isopropyl alcohol, tert. -butyl alcolol

Energy Technology Data Exchange (ETDEWEB)

Take, J; Matsumoto, T; Yoneda, Y

1978-01-01

The dehydration of n-butyl alcohol at 120/sup 0/-166/sup 0/C, sec.-butyl or isopropyl alcohol at 100/sup 0/-145/sup 0/C, and tert.-butyl alcohol at 54/sup 0/-80/sup 0/C, over silica/alumina catalyst was zero order in alcohol at 0.01-0.1 atm, and the activation energies were 35.3, 31.7, 32.0, and 29.9 kcal/mol, respectively. The zero-order rate constants were mainly affected by the activation energies since the preexponential factors varied little except for tert.-butyl alcohol. A linear relationship was found between the activation energy or the logarithm of the zero-order rate constant and the heterolytic bond dissociation energy for the carbon-oxygen bond in alcohols D(R/sup +/OH/sup -/). The activation energy increased and the rate constant decreased with increasing D(R/sup +/OH/sup -/). The results indicate that dehydration is E1 over this catalyst, but a similar correlation was observed based on published data for dehydration over alumina, which follows an E2 mechanism, indicating that heterolytic cleavage of the C-O bond is rate-determining in both mechanisms.

18 CFR 35.14 - Fuel cost and purchased economic power adjustment clauses.

Science.gov (United States)

2010-04-01

... economic power adjustment clauses. 35.14 Section 35.14 Conservation of Power and Water Resources FEDERAL... SCHEDULES AND TARIFFS Other Filing Requirements § 35.14 Fuel cost and purchased economic power adjustment clauses. (a) Fuel adjustment clauses (fuel clause) which are not in conformity with the principles set out...

Catalytic optimization and physicochemical studies over Zn/Ca/Al2O3 catalyst for transesterification of low grade cooking oil

International Nuclear Information System (INIS)

Mohd Kamal, Norhasyimah; Wan Abu Bakar, Wan Azelee; Ali, Rusmidah

2017-01-01

Highlights: • Zn/Ca/Al 2 O 3 has high potential in producing biodiesel. • High basicity favoured high conversion of biodiesel. • Calcination temperature showed the highest influence on the catalytic activity. • RSM was used to determine the optimum operating conditions for biodiesel production. - Abstract: Recently, there has been an increasing interest in green and renewable fuels due to the worldwide concern of an environmental crisis. So, this study focused on the synthesis, optimization and characterization of series of heterostructure Zn/Ca/Al 2 O 3 catalysts with different parameters to test their effectiveness towards biodiesel production. The physicochemical properties of the potential catalyst were determined by BET, FESEM and CO 2 -TPD. The activity of the catalyst in transesterification reaction was evaluated at reaction temperature of 65 °C, 3 h reaction time, 6% (w/w) catalyst concentration and 1:24 M ratio of oil to methanol. The investigation of the synthesized Zn/Ca/Al 2 O 3 catalyst showed that the calcination temperature, number of alumina coatings and dopant to base ratio have significant effects on the catalytic performance. These three critical parameters were investigated using response surface methodology (RSM) with Box Behnken design (BBD) to determine the optimum operating conditions for biodiesel production. From RSM study, the optimum conditions were 800 °C calcination temperature, 3 times alumina beads coating and 10:90 dopant to base ratio which gave 97.80% biodiesel conversion. From the F-value and low p-value (<0.05) obtained showed that the model was significant for predicting the optimum biodiesel conversion. An experiment was conducted under the optimum conditions to confirm the agreement of the model prediction and the experimental results. The experimental value (97.64%) closely agreed with the predicted results from RSM and hence validated the findings of response surface optimization.

Antibacterial activity of zinc oxide-coated nanoporous alumina

Energy Technology Data Exchange (ETDEWEB)

Skoog, S.A. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Bayati, M.R. [Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States); Petrochenko, P.E. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Division of Biology, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993 (United States); Stafslien, S.; Daniels, J.; Cilz, N. [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States); Comstock, D.J.; Elam, J.W. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Narayan, R.J., E-mail: roger_narayan@msn.com [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States)

2012-07-25

Highlights: Black-Right-Pointing-Pointer Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. Black-Right-Pointing-Pointer Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. Black-Right-Pointing-Pointer Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

B2O3/Al2O3 as a new, highly efficient and reusable heterogeneous catalyst for the selective synthesis of β-enamino ketones and esters under solvent-free conditions

International Nuclear Information System (INIS)

Chen, Jiu-Xi; Gao, Wen-Xia; Jin, Hui-Le; Ding, Jin-Chang; Wu, Hua-Yue

2010-01-01

Boron oxide adsorbed on alumina (B 2 O 3 /Al 2 O 3 ) has been found to be a new and highly efficient heterogeneous catalyst for the synthesis of β-enamino ketones and esters by the enamination of various primary and secondary amines with β-dicarbonyl compounds under solvent-free conditions. The important features of this methodology are broad substrate scope, high yield, no requirement of metal catalysts, high regio- and chemoselectivity and environmental friendliness. In addition, the catalyst could be recovered easily after the reactions and reused without evident loss of reactivity. (author)

Yield stress of alumina-zirconia suspensions

International Nuclear Information System (INIS)

Ramakrishnan, V.; Pradip; Malghan, S.G.

1996-01-01

The yield stress of concentrated suspensions of alumina, zirconia, and mixed alumina-zirconia powders was measured by the vane technique as a function of solids loading, relative amounts of alumina and zirconia, and pH. At the isoelectric point (IEP), the yield stress varied as the fourth power of the solids loading. The relative ratio of alumina and zirconia particles was important in determining the yield stress of the suspension at the IEP. The yield stress of single and mixed suspensions showed a marked variation with pH. The maximum value occurred at or near the IEP of the suspension. The effect of electrical double-layer forces on the yield stress can be described on the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. A normalized yield stress--that is, the ratio of the yield stress at a given pH to the yield stress at the IEP predicted by this model--showed good correlation with experimental data

Saving clauses in international contracts concerning the nuclear fuel cycle

International Nuclear Information System (INIS)

Virole, J.; Roubin, J.

1983-01-01

This paper concerns saving clauses in international contracts relating to the fuel cycle. It deals in particular with economic upheavals affecting those contracts and the usual clauses to protect the financial interests of the co-contractors. The paper also examines such economic upheavals in the context of clauses intended to preserve the contracts. (NEA) [fr

Kinetic evaluation of propyne surface diffusivity on silica-alumina-supported chromium(VI) using positron annihilation surface detection

International Nuclear Information System (INIS)

Ferrieri, R.A.; Wolf, A.P.

1984-01-01

A study has been performed on the rate of the translational surface diffusivity of propyne on a silica-alumina-supported Cr(VI) catalyst. This rate was measured via nonchemical acetylene-propyne sorbate interactions coupled with positron annihilation surface detection (PASD). The surface displacement rate of [ 11 C]acetylene by propyne was measured in a transient experiment as a function of the adjacent Cr-site distance and correlated to propyne surface diffusivity, D/sub s/. Results indicated that D/sub s/ increased linearly when the adjacent site distance was decreased for catalysts loaded with between 0.08 and 0.8 wt % of chromium. However, D/sub s/ fell off drastically to nearly zero when greater Cr-site dispersion was achieved at support loadings below 0.08 wt % of chromium. Catalytic selectivity for p-xylene production was also measured as a function of D/sub s/ and was shown to have a strong dependence of its rate. 25 references, 4 figures

LOW TEMPERATURE SINTERING OF ALUMINA BIOCERAMIC UNDER NORMAL PRESSURE

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

Superfine alumina powder with high purity (mean particle size is less than 0. 35μm) were used as main starting material for sintering alumina ceramic. A multiple additive MgO-ZrO2 (Y2O3) was homogeneously added into the batch by the chemical coprecipitation method. Sintering of alumina bioceramic at low tempera ture (＜1600C) was achieved resulting in a dense and high strength alumina ceramic with the bending strength up to 382 MPa and an improved fracture toughness. Mechanism that the multiple additives promote the sintering of alumina ceramic is discussed on the base of XRD and SEM analysis.

Study on the bound water of several high specific surface-area oxides (beryllia, alumina, silica-alumina)

International Nuclear Information System (INIS)

Rouquerol, J.

1964-11-01

This study is concerned with the bound water of several oxides (beryllia, alumina, silica-alumina) at different steps of their dehydration (heating temperatures between 150 and 1100 deg. C). The following techniques have been used simultaneously: Thermal analysis (a new method has been developed), nitrogen adsorption (study of the texture), Diborane hydrolysis (qualitative and quantitative analysis of surface water), Infra-red spectrography (in the absorption range of water), Nuclear magnetic resonance (in the resonance range of protons). Thanks to these different techniques, five kinds of bound water have been observed. Attention is called on the great influence of the thermal treatment conditions on the evolution of the products resulting from the decomposition of alumina α-trihydrate Al(OH) 3 and beryllium α-hydroxide, in the course of the dehydration. Moreover, the author emphasizes the peculiar properties of the two kinds of oxides (alumina and beryllia) prepared through a new method of treatment under low pressure and constant speed of decomposition. Such particular features concern mainly texture, bound water, and consequently, also catalytic activity. (author) [fr

Tree automata-based refinement with application to Horn clause verification

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick

2015-01-01

In this paper we apply tree-automata techniques to refinement of abstract interpretation in Horn clause verification. We go beyond previous work on refining trace abstractions; firstly we handle tree automata rather than string automata and thereby can capture traces in any Horn clause derivation...... compare the results with other state of the art Horn clause verification tools....

Study of the molybdenum retention in alumina

International Nuclear Information System (INIS)

Wilkinson, Maria V.; Mondino, Angel V.; Manzini, Alberto

2002-01-01

The Argentine National Atomic Energy Commission routinely produces 99 Mo by fission of highly enriched uranium contained in targets irradiated in RA-3 reactor. The current process begins with the dissolution of the irradiated target in a basic media, considering the possibility of changing the targets, it could be convenient to dissolve them in acid media. The use of alumina as a first separation step in acid dissolution processes is already known although it is necessary to determine both the type of alumina to be used and the separation conditions. The study of molybdenum retention in alumina was performed at laboratory scale, using Mo-99 as radiotracer. Different kinds of alumina were tried, varying charge solution acidity. Influence of uranium concentration in the loading solution on molybdenum retention was also studied. (author)

Blocking of grain reorientation in self-doped alumina materials

International Nuclear Information System (INIS)

Suarez, M.; Fernandez, A.; Menendez, J.L.; Ramirez-Rico, J.; Torrecillas, R.

2011-01-01

Alumina nanoparticles 10-20 nm in diameter were nucleated on alumina particles, 150 nm average diameter, by a colloidal route followed by calcination. It is shown that after sintering, the final grain size is up to 20% smaller due to the addition of the alumina nanoparticles. Electron backscattered diffraction analysis shows that whereas a correlation in the relative crystalline orientations between neighbouring grains exists in the pure materials, the addition of alumina nanoparticles results in a random crystalline orientation.

48 CFR 3427.472 - Advertising of awards clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Advertising of awards... Copyrights 3427.472 Advertising of awards clause. The contracting officer shall insert the clause in 3452.227-72, Advertising of Awards, in all solicitations and contracts other than purchase orders. ...

48 CFR 3427.470 - Publication and publicity clause.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Publication and publicity... Copyrights 3427.470 Publication and publicity clause. The contracting officer shall insert the clause in 3452.227-70, Publication and Publicity, in all solicitations and contracts other than purchase orders. ...

NMR evidence of metal-support interaction in syngas conversion catalyst Co-TiO2

International Nuclear Information System (INIS)

Murty, A.N.; Seamster, M.; Thorpe, A.N.; Obermyer, R.T.; Rao, V.U.S.

1990-01-01

To examine the relation between catalytic and magnetic properties, the zero-field NMR spectra and hysteresis loops of cobalt supported on silica, alumina, magnesia, titania, and ZSM-5 with and without the promoter thoria were investigated. Cobalt was incorporated on the support by simple physical admixture of precipitated cobalt and support, and by aqueous impregnation technique. Our studies indicate that the particle sizes are consistently lower in the presence of thoria. Of all the catalysts examined, the Co/Th/TiO 2 catalyst exhibits a high saturation magnetization value---about 20% higher than pure cobalt. In addition, the NMR spectrum of the aqueous impregnation Co/TiO 2 catalyst is distinctly different from the rest. All the NMR lines are shifted to a higher frequency by about 4 MHz. These two features---enhancement of the magnetic moment of cobalt atoms and increases in the hyperfine field at the Co nucleus---clearly indicate that there occurs strong metal-support interaction between cobalt and titania support. The higher hydrocarbon yields observed by the earlier investigators with Co/TiO 2 catalysts might be related to this phenomenon

48 CFR 14.201-3 - Part II-Contract clauses.

Science.gov (United States)

2010-10-01

... CONTRACTING METHODS AND CONTRACT TYPES SEALED BIDDING Solicitation of Bids 14.201-3 Part II—Contract clauses... law or by this regulation and any additional clauses expected to apply to any resulting contract, if...

Clause packaging in writing and speech: A cross-linguistic developmental analysis

NARCIS (Netherlands)

Verhoeven, L.T.W.; Aparici, M.; Cahana-Amitay, D.; Hell, J.G. van; Kriz, S.; Vigué-Siom, A.

2002-01-01

This article analyses clause packaging in the written narrative and expository texts in Dutch, English, French, Hebrew, and Spanish by grade-school children and adults. A “clause package” is defined as a text unit consisting of clauses linked by syntactic, thematic, and discursive criteria. Our

Tungsten metallizing alumina--yttria ceramics

International Nuclear Information System (INIS)

Cowan, R.E.; Stoddard, S.D.

1977-03-01

The ease with which high-alumina bodies may be metallized with tungsten is improved by additions of yttria to the alumina. Mechanisms of this bonding process were studied by use of optical and electron microscopy, electron microprobe, and tensile tests. Variables studied included yttria content of the body and the firing temperature during metallizing. The study showed that a reaction between the tungsten and the yttrogarnet grain boundary phase markedly improved adherence

Homogeneous and heterogeneous catalysts of Fe3+, Co2+ and Cu2+ for the degradation of methyl parathion in diluted aqueous medium

Directory of Open Access Journals (Sweden)

Cindy A. Vela-Monroy

2016-07-01

Full Text Available Degradation of pesticides (plaguicides, herbicides, fungicides, among others in aqueous media is a subject of great importance for ensuring the water quality into numerous hydric sources. This work reports the assessment of homogeneous (metal ion solutions and heterogeneous (oxides supported on alumina systems that are based on Fe3+, Co2+ y Cu2+, which were used as catalysts for oxidation (degradation of methyl parathion (a plaguicide in aqueous solution. Hydrogen peroxide was herein used as oxidizing molecule under mild condition of reaction (25 ºC and atmospheric pressure. The solids were characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM. Fe3+/H2O2 (Fenton system was the most active homogeneous catalyst compared to Co2+/H2O2 and Cu2+/H2O2 systems. Solids catalysts such as cobalt, copper or iron oxides as well as mixed oxides supported on alumina were active at pH close to neutrality. Fe-Co-Cu/Al2O3, Co-Cu/Al2O3 and FeCo/Al2O3 mixed systems were solids with the highest catalytic activity. In addition, an important effect of the support (-Al2O3 on the reaction pH was observed, allowing to reach values close to that of the neutrality, and thus increasing the catalytic activity of both cobalt oxide and copper oxide species. These results allow advancing on a new pathway for searching catalysts to remove organophosphorous pesticides from residual waters.

Antimicrobial Properties of Chitosan-Alumina/f-MWCNT Nano composites

International Nuclear Information System (INIS)

Masheane, M.; Nthunya, L.; Malinga, S.; Masheane, M.; Nthunya, L.; Nxumalo, E.; Mhlanga, S.; Barnard, T.

2016-01-01

Antimicrobial chitosan-alumina/functionalized-multi walled carbon nano tube (f-MWCNT) nano composites were prepared by a simple phase inversion method. Scanning electron microscopy (SEM) analyses showed the change in the internal morphology of the composites and energy dispersive spectroscopy (EDS) confirmed the presence of alumina and f-MWCNTs in the chitosan polymer matrix. Fourier transform infrared (FTIR) spectroscopy showed the appearance of new functional groups from both alumina and f-MWCNTs, and thermogravimetric analysis (TGA) revealed that the addition of alumina and f-MWCNTs improved the thermal stability of the chitosan polymer. The presence of alumina and f-MWCNTs in the polymer matrix was found to improve the thermal stability and reduced the solubility of chitosan polymer. The prepared chitosan-alumina/f-MWCNT nano composites showed inhibition of twelve strains of bacterial strains that were tested. Thus, the nano composites show a potential for use as a biocides in water treatment for the removal of bacteria at different environmental conditions.

Enriched fluoride sorption using alumina/chitosan composite

Energy Technology Data Exchange (ETDEWEB)