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Sample records for catalytic wet oxidation

  1. Graphene-based materials in catalytic wet peroxide oxidation

    OpenAIRE

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

    2014-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    徐新华; 汪大翬

    2003-01-01

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

  3. Process of forming catalytic surfaces for wet oxidation reactions

    Science.gov (United States)

    Jagow, R. B. (Inventor)

    1977-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-30

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  8. Copper on activated carbon for catalytic wet air oxidation

    Directory of Open Access Journals (Sweden)

    Nora Dolores Martínez

    2009-03-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-31

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

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

    OpenAIRE

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

    2011-01-01

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

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

    Science.gov (United States)

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

    1987-01-01

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

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

    Science.gov (United States)

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

    2007-06-18

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-06-18

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2014-01-01

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

  18. Pretreatment of apramycin wastewater by catalytic wet air oxidation

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

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

    OpenAIRE

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

    2015-01-01

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

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

    OpenAIRE

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

    2013-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    LI Ning; LI Guangming; YAO Zhenya; ZHAO Jianfu

    2007-01-01

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

  3. Carbon nanotubes: a suitable material for catalytic wet peroxide oxidation of organic pollutants?

    OpenAIRE

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

    2012-01-01

    Carbon materials, such as activated carbons (AC), graphite and activated carbon xerogels, have been explored as metal-free catalysts for the catalytic wet peroxide oxidation (CWPO) of bio-refractory organic compounds, such as azo dyes and phenolic compounds [1-3]. At the same time, the application of carbon nanomaterials in catalysis, such as carbon nanotubes (CNT), has grown exponentially [4]. In the present work, commercial multiwalled carbon nanotubes (MWNT) were used in the CWPO of 2-nitr...

  4. The influence of carbon material properties on the efficiency of catalytic wet peroxide oxidation processes

    OpenAIRE

    Gomes, Helder; R. Ribeiro; Silva, Adrián; Figueiredo, José; Faria, Joaquim

    2015-01-01

    Carbon materiais are well known catalysts for activatin§ H^O^ into hydroxyl radicais (HO'), which are efficient oxidizin § agents. By making use of highly reactive HO" radicais, the elimination of organic compounds can be accomplished by catalytic wet peroxide oxidation (CWPO), a water treatment technology operating under mild conditions of pressure and temperature that hás gained importance due to the decreasing cost of H;0; and its increasing use in wastewater treatm...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-10-01

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

  6. Catalytic wet oxidation of thiocyanate with homogeneous copper(II) sulphate catalyst

    International Nuclear Information System (INIS)

    The wet oxidation of thiocyanate has been investigated in a semi-batch reactor at temperatures between 423 and 473 K and pressures between 6.1 x 103 and 1.0 x 104 kPa in the presence of copper(II) sulphate as catalyst. The effects of copper concentration, initial thiocyanate concentration, pressure and temperature on the reaction rate were analyzed and the main products of reaction were identified. A kinetic model for the Cu-catalyzed reaction is here proposed, including temperature, oxygen concentration, and the reduction of Cu2+ to Cu+ that gives an accurate prediction of the oxidation process under the assayed conditions. A mechanistic model based on the formation of a transition complex between a copper cation and two thiocyanate anions has been proposed for the catalytic wet oxidation.

  7. Application of Catalytic Wet Air Oxidation to Treatment of Landfill Leachate on Co/Bi Catalyst

    Institute of Scientific and Technical Information of China (English)

    LI Hai-sheng; LIU Liang; ZHANG Rong; DONG De-ming; LIU Hong-liang; LI Yu

    2004-01-01

    Catalytic wet air oxidation(CWAO) was employed to reduce the organic compounds in landfill leachate and the effects of temperature, oxygen pressure, catalyst dosage, and concentration of the organic compounds on the TOC and CODCr removal rates were studied. The degradation kinetics of landfill leachate was also investigated and an exponential experiential model consisting of four influential factors was established to describe the reduction of the organic compounds in the landfill leachate. Meanwhile, the GC-MS technique was used to detect the components of the organic intermediates for the inference of the decomposition mechanisms of the organic compounds in landfill leachate. The results reveal that the reaction temperature and the catalyst dosage are the most important factors affecting the degradation reaction of the organic compounds and that the principal intermediates confirmed by GC-MS are organic acids at a percentage of more than 88% with no aldehydes or alcohols detected. The decomposition mechanisms of the organic compounds in landfill leachate were inferred based on the GC-MS information as follows: the activated gas phase O2 captured the hydrogen of the organic pollutants to produce free radicals, which then initiated the catalytic reaction. So most of the organic compounds were oxidized into CO2 and H2O ultimately. In general, catalytic wet air oxidation over catalyst Co3O4/Bi2O3 was a very promising technique for the treatment of landfill leachate.

  8. Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Yuting [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Xiong, Ya; Tian, Shuanghong [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275 (China); Kong, Lingjun [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Descorme, Claude, E-mail: claude.descorme@ircelyon.univ-lyon1.fr [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

    2014-07-15

    Highlights: • A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared. • FeSC exhibited high catalytic activity in the wet air oxidation of 2-chlorophenol. • A strong correlation was observed between the 2-CP conversion, the iron leaching and the pH. • Using an acetate buffer, the iron leaching was suppressed while keeping some catalytic activity. • A simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst. - Abstract: A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pH{sub PZC}, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120 °C under 0.9 MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5 h and 90% Total Organic Carbon (TOC) was removed after 24 h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst.

  9. Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts

    International Nuclear Information System (INIS)

    Highlights: • A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared. • FeSC exhibited high catalytic activity in the wet air oxidation of 2-chlorophenol. • A strong correlation was observed between the 2-CP conversion, the iron leaching and the pH. • Using an acetate buffer, the iron leaching was suppressed while keeping some catalytic activity. • A simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst. - Abstract: A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pHPZC, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120 °C under 0.9 MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5 h and 90% Total Organic Carbon (TOC) was removed after 24 h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst

  10. Catalytic wet peroxide oxidation of phenol solutions over CuO/CeO2 systems

    International Nuclear Information System (INIS)

    Three 5% CuO/CeO2 catalysts were synthesized by sol-gel, precipitation and combustion methods, followed by incipient wetness impregnation with copper nitrate. The samples were characterized by XRD, TPR, BET and tested for the catalytic wet peroxide oxidation of a phenol solution (5 g/L). The reaction took place in a batch reactor at atmospheric pressure, in a temperature range of 60-80°C , during 4 h. Phenol conversion, H2O2 consumption, pH and chemical oxygen demand were determined. The reaction temperature and the catalyst loading did improve the phenol and the H2O2 conversions. The effect on the selectivity towards complete mineralization was less marked, with levels among 60-70%. Stepwise addition of H2O2 was also tested.

  11. Chloride ions promoted the catalytic wet peroxide oxidation of phenol over clay-based catalysts.

    Science.gov (United States)

    Zhou, Shiwei; Zhang, Changbo; Xu, Rui; Gu, Chuantao; Song, Zhengguo; Xu, Minggang

    2016-01-01

    Catalytic wet peroxide oxidation (CWPO) of phenol over clay-based catalysts in the presence and absence of NaCl was investigated. Changes in the H2O2, Cl(-), and dissolved metal ion concentration, as well as solution pH during phenol oxidation, were also studied. Additionally, the intermediates formed during phenol oxidation were detected by liquid chromatography-mass spectroscopy and the chemical bonding information of the catalyst surfaces was analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that the presence of Cl(-) increased the oxidation rate of phenol to 155%, and this phenomenon was ubiquitous during the oxidation of phenolic compounds by H2O2 over clay-based catalysts. Cl(-)-assisted oxidation of phenol was evidenced by several analytical techniques such as mass spectroscopy (MS) and XPS, and it was hypothesized that the rate-limiting step was accelerated in the presence of Cl(-). Based on the results of this study, the CWPO technology appears to be promising for applications in actual saline phenolic wastewater treatment. PMID:26942523

  12. Conversion of the refractory ammonia and acetic acid in catalytic wet air oxidation of animal byproducts

    Institute of Scientific and Technical Information of China (English)

    Virginie Fontanier; Sofiane Zalouk; Stéphane Barbati

    2011-01-01

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) of slaughtered animal byproducts (ABPs) were investigated.Two step experiment was carried out consisting ofa non-catalysed WAO run followed by a CWAO run at 170-275℃, 20 MPa, and reaction time 180 min.The WAO (1st step) of sample (5 g/L total organic carbon (TOC)) yielded (82.0 ± 4)% TOC removal and (78.4 ± 13.2)%conversion of the initial organic-N into NH4+-N.Four metal catalysts (Pd, Pt, Rh, Ru) supported over alumina have been tested in catalytic WAO (2nd step) at elevated pH to enhance ammonia conversion and organic matter removal, particularly acetic acid.It was found that the catalysts Ru, Pt, and Rh had significant effects on the TOC removal (95.1%, 99.5% and 96.7%, respectively) and on the abatement of ammonia (93.4%, 96.7% and 96.3%, respectively) with high nitrogen selectivity.The catalyst Pd was found to have the less activity while Pt had the best performance.The X-Ray diffraction analysis showed that the support of catalyst was not stable under the experimental conditions since it reacted with phosphate present in solution.Nitrite and nitrate ions were monitored during the oxidation reaction and it was concluded that CWAO of ammonia in real waste treatment framework was in good agreement with the results obtained from the literature for ideal solutions of ammonia.

  13. Study on Catalytic Wet Oxidation of H2S into Sulfur on Fe/Cu Catalyst

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A wet catalytic oxidation at room temperature was investigated with solution containing ferric, ferrous and cupric ions for H2S removal. The experiments were carried out in a two step process,and the results obtained show that the removal efficiency of H2S can always reach 100% in a 300 mm scrubbing column with four sieve plates, and the regeneration of ferric ions in 200 mm bubble column can match the consumed ferric species in absorption. Removal of H2S, production of elemental sulfur and regeneration of ferric, cupric ions can all be accomplished at the same time. No raw material is consumed except O2 in flue gas or air, the process has no secondary pollution and no problem of catalyst degradation and congestion.

  14. Catalytic wet oxidation of ammonia solution: Activity of the nanoscale platinum-palladium-rhodium composite oxide catalyst

    International Nuclear Information System (INIS)

    Aqueous solutions of 400-1000 mg/L of ammonia were oxidized in a trickle-bed reactor (TBR) in this study of nanoscale platinum-palladium-rhodium composite oxide catalysts, which were prepared by the co-precipitation of H2PtCl6, Pd(NO3)3 and Rh(NO3)3. Hardly any of the dissolved ammonia was removed by wet oxidation in the absence of any catalyst, whereas about 99% of the ammonia was reduced during wet oxidation over nanoscale platinum-palladium-rhodium composite oxide catalysts at 503 K in an oxygen partial pressure of 2.0 MPa. A synergistic effect exists in the nanoscale platinum-palladium-rhodium composite structure, which is the material with the highest ammonia reduction activity. The nanometer-sized particles were characterized by TEM, XRD and FTIR. The effect of the initial concentration and reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid hourly space velocity of under 9 h-1 in the wet catalytic processes

  15. A kinetic model of municipal sludge degradation during non-catalytic wet oxidation.

    Science.gov (United States)

    Prince-Pike, Arrian; Wilson, David I; Baroutian, Saeid; Andrews, John; Gapes, Daniel J

    2015-12-15

    Wet oxidation is a successful process for the treatment of municipal sludge. In addition, the resulting effluent from wet oxidation is a useful carbon source for subsequent biological nutrient removal processes in wastewater treatment. Owing to limitations with current kinetic models, this study produced a kinetic model which predicts the concentrations of key intermediate components during wet oxidation. The model was regressed from lab-scale experiments and then subsequently validated using data from a wet oxidation pilot plant. The model was shown to be accurate in predicting the concentrations of each component, and produced good results when applied to a plant 500 times larger in size. A statistical study was undertaken to investigate the validity of the regressed model parameters. Finally the usefulness of the model was demonstrated by suggesting optimum operating conditions such that volatile fatty acids were maximised. PMID:26426294

  16. Catalytic wet oxidation of the pretreated synthetic pulp and paper mill effluent under moderate conditions.

    Science.gov (United States)

    Garg, Anurag; Mishra, I M; Chand, Shri

    2007-01-01

    In the present study, catalytic wet oxidation (CWO) was investigated for the destruction of organic pollutants in the thermally pretreated effluent from a pulp and paper mill under moderate temperature and pressure conditions. The thermal pretreatment studies were conducted at atmospheric pressure and 368K using copper sulfate as a catalyst. The thermal pretreatment reduced COD by about 61%. The filtrate of the thermal pretreatment step was used at pH 8.0 for CWO at 383-443K temperature and a total pressure of 0.85MPa for 4h. Catalysts used for the reaction include copper sulfate, 5% CuO/95% activated carbon, 60% CuO/40% MnO(2), and 60% CuO/40% CeO(2). Maximum COD reduction was found to be 89% during CWO step using 5% CuO/95% activated carbon with a catalyst loading of 8gl(-1) at 443K and 0.85MPa total pressure. Overall COD reduction for the pretreatment and the CWO was found to be 96%. Besides this, 60% CuO/40% CeO(2) catalyst also exhibited the similar activity as that of obtained with 5% CuO/95% activated carbon catalyst at 423K temperature and 0.85MPa total pressure. The pH of the solution during the experimental runs decreases initially due to the formation of carboxylic acid and then increases due to the decomposition of acids. PMID:16934854

  17. Supported noble metal catalysts in the catalytic wet air oxidation of industrial wastewaters and sewage sludges.

    Science.gov (United States)

    Besson, M; Descorme, C; Bernardi, M; Gallezot, P; di Gregorio, F; Grosjean, N; Minh, D Pham; Pintar, A

    2010-12-01

    This paper reviews some catalytic wet air oxidation (CWAO) investigations of industrial wastewaters over platinum and ruthenium catalysts supported on TiO2 and ZrO2 formulated to be active and resistant to leaching, with particular focus on the stability of the catalyst. Catalyst recycling experiments were performed in batch reactors and long-term stability tests were conducted in trickle-bed reactors. The catalyst did not leach upon treatment of Kraft bleaching plant and olive oil mill effluents, and could be either recycled or used for long periods of time in continuous reactors. Conversely, these catalysts were rapidly leached when used to treat effluents from the production of polymeric membranes containing N,N-dimethylformamide. The intermediate formation of amines, such as dimethylamine and methylamine with a high complexing capacity for the metal, was shown to be responsible for the metal leaching. These heterogeneous catalysts also deactivated upon CWAO of sewage sludges due to the adsorption of the solid organic matter. Pre-sonication of the sludge to disintegrate the flocs and improve solubility was inefficient. PMID:21214003

  18. Development of a Catalytic Wet Air Oxidation Method to Produce Feedstock Gases from Waste Polymers

    Science.gov (United States)

    Kulis, Michael J.; Guerrero-Medina, Karen J.; Hepp, Aloysius F.

    2012-01-01

    Given the high cost of space launch, the repurposing of biological and plastic wastes to reduce the need for logistical support during long distance and long duration space missions has long been recognized as a high priority. Described in this paper are the preliminary efforts to develop a wet air oxidation system in order to produce fuels from waste polymers. Preliminary results of partial oxidation in near supercritical water conditions are presented. Inherent corrosion and salt precipitation are discussed as system design issues for a thorough assessment of a second generation wet air oxidation system. This work is currently being supported by the In-Situ Resource Utilization Project.

  19. Catalytic oxidation with Al-Ce-Fe-PILC as a post-treatment system for coffee wet processing wastewater.

    Science.gov (United States)

    Sanabria, Nancy R; Peralta, Yury M; Montañez, Mardelly K; Rodríguez-Valencia, Nelson; Molina, Rafael; Moreno, Sonia

    2012-01-01

    The effluent from the anaerobic biological treatment of coffee wet processing wastewater (CWPW) contains a non-biodegradable compound that must be treated before it is discharged into a water source. In this paper, the wet hydrogen peroxide catalytic oxidation (WHPCO) process using Al-Ce-Fe-PILC catalysts was researched as a post-treatment system for CWPW and tested in a semi-batch reactor at atmospheric pressure and 25 °C. The Al-Ce-Fe-PILC achieved a high conversion rate of total phenolic compounds (70%) and mineralization to CO(2) (50%) after 5 h reaction time. The chemical oxygen demand (COD) of coffee processing wastewater after wet hydrogen peroxide catalytic oxidation was reduced in 66%. The combination of the two treatment methods, biological (developed by Cenicafé) and catalytic oxidation with Al-Ce-Fe-PILC, achieved a 97% reduction of COD in CWPW. Therefore, the WHPCO using Al-Ce-Fe-PILC catalysts is a viable alternative for the post-treatment of coffee processing wastewater. PMID:22907449

  20. Combination of coagulation and catalytic wet oxidation for the treatment of pulp and paper mill effluents.

    Science.gov (United States)

    Verenich; Laari, A; Nissen, M; Kallas, J

    2001-01-01

    Wet oxidation (WO) is a well established process for purification of concentrated municipal and industrial wastewaters. Many attempts have been made to modify the WO process or to create a suitable combination of processes. This work was undertaken to investigate wet oxidation integrated with coagulation, i.e. to treat the sludge remaining after coagulation with a WO process. The possibility of regeneration of the used coagulant was also considered. Two waters from paper mills were used: TMP (thermomechanical pulp) circulation water and membrane concentrate. About 50% of the COD in the original water can be removed by coagulation using Fe2(SO4)3. The results from the wet oxidation experiments show the positive effect of iron in the chemical sludge as a catalyst. The efficiency of the WO process was enhanced almost by 100%. The remaining dissolved organic matter can be easily removed biologically. PMID:11695452

  1. A compact process for the treatment of olive mill wastewater by combining wet hydrogen peroxide catalytic oxidation and biological techniques

    International Nuclear Information System (INIS)

    A system based on combined actions of catalytic wet oxidation and microbial technologies for the treatment of highly polluted OMW containing polyphenols was studied. The wet hydrogen peroxide catalytic oxidation (WHPCO) process has been investigated in the semi-batch mode at atmospheric pressure, using aluminium-iron-pillared inter layer clay ((Al-Fe)PILC), under two different catalytic processes: ((Al-Fe)PILC/H2O2/ultraviolet radiations) at 25 deg. C and ((Al-Fe)PILC/H2O2) at 50 deg. C. The results show that raw OMW was resistant to the photocatalytic process. However ((Al-Fe)PILC/H2O2), system operating at 50 deg. C reduced considerably the COD, colour and total phenolic contents, and thus decreased the inhibition of the marine photobacteria Vibrio fischeri luminescence by 70%. This study also examined the feasibility of coupling WHPCO and anaerobic digestion treatment. Biomethanisation experiments performed with raw OMW or pre-treated OMW proved that pre-treatments with ((Al-Fe)PILC/H2O2) system, for more than 2 h, resulted in higher methane production. Both untreated OMW as well as 2-h pre-treated OMW revealed as toxic to anaerobic bacteria.

  2. A compact process for the treatment of olive mill wastewater by combining wet hydrogen peroxide catalytic oxidation and biological techniques

    Energy Technology Data Exchange (ETDEWEB)

    Azabou, Samia [Laboratoire des BioProcedes, Centre de Biotechnologie de Sfax, BP 1177, 3018 Sfax (Tunisia); Najjar, Wahiba [Laboratoire de Chimie des Materiaux et Catalyse, Faculte des Sciences de Tunis, Campus Universitaire, 2092 Tunis (Tunisia); Bouaziz, Mohamed [Laboratoire des BioProcedes, Centre de Biotechnologie de Sfax, BP 1177, 3018 Sfax (Tunisia); Ghorbel, Abdelhamid [Laboratoire de Chimie des Materiaux et Catalyse, Faculte des Sciences de Tunis, Campus Universitaire, 2092 Tunis (Tunisia); Sayadi, Sami, E-mail: sami.sayadi@cbs.rnrt.tn [Laboratoire des BioProcedes, Centre de Biotechnologie de Sfax, BP 1177, 3018 Sfax (Tunisia)

    2010-11-15

    A system based on combined actions of catalytic wet oxidation and microbial technologies for the treatment of highly polluted OMW containing polyphenols was studied. The wet hydrogen peroxide catalytic oxidation (WHPCO) process has been investigated in the semi-batch mode at atmospheric pressure, using aluminium-iron-pillared inter layer clay ((Al-Fe)PILC), under two different catalytic processes: ((Al-Fe)PILC/H{sub 2}O{sub 2}/ultraviolet radiations) at 25 deg. C and ((Al-Fe)PILC/H{sub 2}O{sub 2}) at 50 deg. C. The results show that raw OMW was resistant to the photocatalytic process. However ((Al-Fe)PILC/H{sub 2}O{sub 2}), system operating at 50 deg. C reduced considerably the COD, colour and total phenolic contents, and thus decreased the inhibition of the marine photobacteria Vibrio fischeri luminescence by 70%. This study also examined the feasibility of coupling WHPCO and anaerobic digestion treatment. Biomethanisation experiments performed with raw OMW or pre-treated OMW proved that pre-treatments with ((Al-Fe)PILC/H{sub 2}O{sub 2}) system, for more than 2 h, resulted in higher methane production. Both untreated OMW as well as 2-h pre-treated OMW revealed as toxic to anaerobic bacteria.

  3. Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production

    OpenAIRE

    Sales F.G.; Abreu C.A.M.; Pereira J. A. F. R.

    2004-01-01

    In the present work a process of catalytic wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found. For the purpose o...

  4. Development of the Monolith Froth Reactor for Catalytic Wet Oxidation of CELSS Model Wastes

    Science.gov (United States)

    Abraham, Martin; Fisher, John W.

    1995-01-01

    The aqueous phase oxidation of acetic acid, used as a model compound for the treatment of CELSS (Controlled Ecological Life Support System) waste, was carried out in the monolith froth reactor which utilizes two-phase flow in the monolith channels. The catalytic oxidation of acetic acid was carried out over a Pt/Al2O3 catalyst, prepared at The University of Tulsa, at temperatures and pressures below the critical point of water. The effect of externally controllable parameters (temperature, liquid flow rate, distributor plate orifice size, pitch, and catalyst distance from the distributor plate) on the rate of acetic acid oxidation was investigated. Results indicate reaction rate increased with increasing temperature and exhibited a maximum with respect to liquid flow rate. The apparent activation energy calculated from reaction rate data was 99.7 kJ/mol. This value is similar to values reported for the oxidation of acetic acid in other systems and is comparable to intrinsic values calculated for oxidation reactions. The kinetic data were modeled using simple power law kinetics. The effect of "froth" feed system characteristics was also investigated. Results indicate that the reaction rate exhibits a maximum with respect to distributor plate orifice size, pitch, and catalyst distance from the distributor plate. Fundamental results obtained were used to extrapolate where the complete removal of acetic acid would be obtained and for the design and operation of a full scale CELSS treatment system.

  5. Influence of the different oxidation treatment on the performance of multi-walled carbon nanotubes in the catalytic wet air oxidation of phenol

    International Nuclear Information System (INIS)

    Highlights: ► Carbon nanotubes were used as catalysts in the catalytic wet air oxidation of phenol. ► Four chemical oxidants (HNO3/H2SO4, H2O2, O3 and air) were used to modify the CNTs. ► The O3-functionalized CNTs exhibit the highest activity and the perfect stability. - Abstract: Multi-walled carbon nanotubes (MWCNTs) functionalized by different oxidants (HNO3/H2SO4, H2O2, O3 and air) have been used as catalysts for the wet air oxidation of phenol. To investigate the effect of the oxidation conditions on the structure of the functionalized MWCNTs, various characterization techniques, e.g., scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been used. The MWCNTs treated with O3 and H2O2 show higher amounts of oxygen-containing functional groups and carboxylic acid groups, and a weaker acidic nature, in comparison with those treated with other oxidizing agents. All the functionalized MWCNTs exhibit good activity in the catalytic wet air oxidation (CWAO) of phenol. However, the MWCNTs treated with O3 show the highest activity with desirable stability in comparison with other functionalized MWCNTs, indicating that the functionalization of carbon nanotubes with O3 is a very promising strategy in synthesizing efficient catalysts for CWAO.

  6. Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production

    Directory of Open Access Journals (Sweden)

    Sales F.G.

    2004-01-01

    Full Text Available In the present work a process of catalytic wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found. For the purpose of producing aromatic aldehydes in continuous regime, a three-phase fluidized reactor was built, and it was operated using atmospheric air as the oxidizer. The best yield in aromatic aldehydes was of 12%. The experimental results were compatible with those values obtained by the pseudo-heterogeneous axial dispersion model (PHADM applied to the liquid phase.

  7. Inhibition and deactivation effects in catalytic wet oxidation of high-strength alcohol-distillery liquors

    Energy Technology Data Exchange (ETDEWEB)

    Belkacemi, K.; Larachi, F.; Hamoudi, S.; Turcotte, G.; Sayari, A. [Laval Univ., Sainte-Foy, Quebec (Canada)

    1999-06-01

    The removal efficiency of total organic carbon (TOC) from raw high-strength alcohol-distillery waste liquors was evaluated using three different treatments: thermolysis (T), noncatalytic wet oxidation (WO), and solid-catalyzed wet oxidation (CWO). The distillery liquors (TOC = 22,500 mg/l, sugars = 18,000 mg/l, and proteins = 13,500 mg/l) were produced by alcoholic fermentation of enzymatic hydrolyzates from steam-exploded timothy grass. TOC-abatement studies were conducted batchwise in a stirred autoclave to evaluate the influence of the catalyst (7:3, MnO{sub 2}/CeO{sub 2} mixed oxide), oxygen partial pressure (0.5--2.5 MPa), and temperature (453--523 K) on T, WO, and CWO processes. Although CWO outperformed T and WO, TOC conversions did not exceed {approximately}60% at the highest temperature used. Experiments provided prima facie evidence for a gradual fouling of the catalyst and a developing inhibition in the liquors which impaired deep TOC removals. Occurrence of catalyst deactivation by carbonaceous deposits was proven experimentally through quantitative and qualitative experiments such as elemental analysis and X-ray photoelectron spectroscopy. Inhibition toward further degradation of the liquors was ascribed to the occurrence of highly stable antioxidant intermediates via the Maillard reactions between dissolved sugars and proteins. A lumping kinetic model involving both reaction inhibition by dissolved intermediates and catalyst deactivation by carbonaceous deposits was proposed to account for the distribution of carbon in the liquid, solid, and the vapor phases.

  8. Catalytic wet peroxide oxidation of aniline in wastewater using copper modified SBA-15 as catalyst.

    Science.gov (United States)

    Kong, Liming; Zhou, Xiang; Yao, Yuan; Jian, Panming; Diao, Guowang

    2016-01-01

    SBA-15 mesoporous molecular sieves modified with copper (Cu-SBA-15) were prepared by pH-adjusting hydrothermal method and characterized by X-ray diffraction, BET, transmission electron microscopy, UV-Vis and (29)Si MAS NMR. The pH of the synthesis gel has a significant effect on the amount and the dispersion of copper on SBA-15. The Cu-SBA-15(4.5) (where 4.5 denotes the pH value of the synthesis gel) modified with highly dispersed copper was used as catalyst for the oxidation of aniline by H2O2. The Cu-SBA-15(4.5) shows a higher catalytic activity compared to CuO on the surface of SBA-15. The influences of reaction conditions, such as initial pH of the aqueous solutions, temperature, as well as the dosages of H2O2 and catalyst were investigated. Under weakly alkaline aqueous solution conditions, the aniline conversion, the H2O2 decomposition and the total organic carbon (TOC) removal could be increased significantly compared to the acid conditions. The percentage of leaching Cu(2+) could be decreased from 45.0% to 3.66% when the initial pH of solution was increased from 5 to 10. The TOC removal could be enhanced with the increases of temperature, H2O2 and catalyst dosage, but the aniline conversion and H2O2 decomposition change slightly with further increasing dosage of catalyst and H2O2. At 343 K and pH 8.0, 100% aniline conversion and 66.9% TOC removal can be achieved under the conditions of 1.0 g/L catalyst and 0.05 mol/L H2O2 after 180 min. Although copper might be slightly leached from catalyst, the homogeneous Cu(2+) contribution to the whole catalytic activity is unimportant, and the highly dispersed copper on SBA-15 plays a dominant role. PMID:26227827

  9. Thermodynamic and kinetic study of phenol degradation by a non-catalytic wet air oxidation process.

    Science.gov (United States)

    Lefèvre, Sébastien; Boutin, Olivier; Ferrasse, Jean-Henry; Malleret, Laure; Faucherand, Rémy; Viand, Alain

    2011-08-01

    This work is dedicated to an accurate evaluation of thermodynamic and kinetics aspects of phenol degradation using wet air oxidation process. Phenol is a well known polluting molecule and therefore it is important having data of its behaviour during this process. A view cell is used for the experimental study, with an internal volume of 150 mL, able to reach pressures up to 30 MPa and temperatures up to 350°C. Concerning the thermodynamic phase equilibria, experimental and modelling results are obtained for different binary systems (water/nitrogen, water/air) and ternary system (water/nitrogen/phenol). The best model is the Predictive Soave Redlich Kwong one. This information is necessary to predict the composition of the gas phase during the process. It is also important for an implementation in a process simulation. The second part is dedicated to kinetics evaluation of the degradation of phenol. Different compounds have been detected using GC coupled with a MS. A kinetic scheme is deduced, taking into account the evolution of phenol, hydroquinones, catechol, resorcinol and acetic acid. The kinetic parameters are calculated for this scheme. These data are important to evaluate the evolution of the concentration of the different polluting molecules during the process. A simplified kinetic scheme, which can be easily implemented in a process simulation, is also determined for the direct degradation of phenol into H(2)O and CO(2). The Arrhenius law data obtained for the phenol disappearance are the following: k=1.8×10(6)±3.9×10(5)M(-1)s(-1) (pre-exponential factor) and E(a)=77±8 kJ mol(-1) (activation energy). PMID:21700312

  10. CATALYTIC WET PEROXIDE OXIDATION OF HYDROQUINONE WITH Co(II)/ACTIVE CARBON CATALYST LOADED IN STATIC BED

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Catalysts based on Co(II) supported on active carbon were prepared and loaded in static bed. The hydroquinone would be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(II)/active carbon catalyst. After activate treatment, the active carbon was immerged in cobaltous nitrate solution, then put into a drying oven, Co(II) could be loaded on the micro-surface of carbon. Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(II) was used to reduce activation energy of hydroquinone. Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard. Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(II). The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃ , pH 5 and reaction time 2.5h.

  11. CATALYTIC WET PEROXIDE OXIDATION OF HYDROQUINONE WITH Co(Ⅱ)/ACTIVE CARBON CATALYST LOADED IN STATIC BED

    Institute of Scientific and Technical Information of China (English)

    LI Chunxiang; YAN Yongsheng; XU Wanzhen

    2008-01-01

    Catalysts based on Co(Ⅱ) supported on active carbon were prepared and loaded in static bed.The hydroquinone wouid be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(Ⅱ)/active carbon catalyst.After activate treatment, the active carbon was immerged in cobaltoas nitrate solution, then put into a drying oven, Co(Ⅱ) could be loaded on the micro-surface of carbon.Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(Ⅱ) was used to reduce activation energy of hydroquinone.Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard.Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(Ⅱ).The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃, pH 5 and reaction time 2.5h.

  12. Wet oxidation of quinoline

    DEFF Research Database (Denmark)

    Thomsen, A.B.; Kilen, H.H.

    1998-01-01

    The influence of oxygen pressure (0.4 and 2 MPa). reaction time (30 and 60 min) and temperature (260 and 280 degrees C) on the wet oxidation of quinoline has been studied. The dominant parameters for the decomposition of quinoline were oxygen pressure and reaction temperature. whereas the reaction...... time was less important within the range studied. Nitrifying bacteria were used to measure the inhibition from wet oxidative-treated samples to study the effect of the (wet oxidation) reaction conditions. Wet oxidation made quinoline more toxic to Nitrosomonas. This was observed for Nitrobacter as well....... The combined wet oxidation and biological treatment of reaction products resulted in 91% oxidation of the parent compound to CO2 and water. Following combined wet oxidation and biological treatment the sample showed low toxicity towards Nitrosomonas and no toxicity towards Nitrobacter. (C) 1998 Elsevier...

  13. Resting Study of Tracer Experiment on Catalytic Wet Oxidation Reactor under Micro-gravity and Earth Gravity Conditions

    Institute of Scientific and Technical Information of China (English)

    YANG Ji; JIA Jin-ping

    2005-01-01

    The International Space Station(ISS) employs catalytic wet oxidation carried out in a Volatile Reactor Assembly (VRA) for water recycling. Previous earth gravity experiments show that the VRA is very effective at removing polar,low molecular weight organics. To compare the reactor performance under micro-gravity and Earth gravity conditions,a tracer study was performed on a space shuttle in 1999 by using 0. 2% potassium carbonate as the chemical tracer.In this paper, the experimental data were analyzed and it is indicated that the reactor can be considered as a plug flow one under both micro-gravity and earth gravity experimental conditions. It has also been proved that dispersion is not important in the VRA reactor under the experimental conditions. Tracer retardation was observed in the experiments and it is most likely caused by catalyst adsorption. It is concluded that the following reasons may also have influence on the retardation of mean residence time: (1) the liquid can be held by appurtenances, which will retard the mean residence time; (2) the pores can hold the tracer, which can also retard the mean residence time.

  14. Catalytic Wet Air Oxidation of o-Chlorophenol in Wastewater%邻氯苯酚废水的催化湿式氧化处理

    Institute of Scientific and Technical Information of China (English)

    徐新华; 汪大翚

    2003-01-01

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

  15. Toxicity to Daphnia magna and Vibrio fischeri of Kraft bleach plant effluents treated by catalytic wet-air oxidation.

    Science.gov (United States)

    Pintar, Albin; Besson, Michèle; Gallezot, Pierre; Gibert, Janine; Martin, Dominique

    2004-01-01

    Two Kraft-pulp bleaching effluents from a sequence of treatments which include chlorine dioxide and caustic soda were treated by catalytic wet-air oxidation (CWAO) at T=463 K in trickle-bed and batch-recycle reactors packed with either TiO2 extrudates or Ru(3 wt%)/TiO2 catalyst. Chemical analyses (TOC removal, color, HPLC) and bioassays (48-h and 30-min acute toxicity tests using Daphnia magna and Vibrio fischeri, respectively) were used to get information about the toxicity impact of the starting effluents and of the treated solutions. Under the operating conditions, complex organic compounds are mostly oxidized into carbon dioxide and water, along with short-chain carboxylic acids. Bioassays were found as a complement to chemical analyses for ensuring the toxicological impact on the ecosystem. In spite of a large decrease of TOC, the solutions of end products were all more toxic to Daphnia magna than the starting effluents by factors ranging from 2 to 33. This observation is attributed to the synergistic effects of acetic acid and salts present in the solutions. On the other hand, toxicity reduction with respect to Vibrio fischeri was achieved: detoxification factors greater than unity were measured for end-product solutions treated in the presence of the Ru(3 wt%)/TiO2 catalyst, suggesting the absence of cumulative effect for this bacteria, or a lower sensitivity to the organic acids and salts. Bleach plant effluents treated by the CWAO process over the Ru/TiO2 catalyst were completely biodegradable. PMID:14675640

  16. Investigation on preparation of CuO-SnO2-CeO2/γ-Al2O3 catalysts for catalytic wet air oxidation process and their catalytic activity for degradation of phenol

    Institute of Scientific and Technical Information of China (English)

    SUN Xiao-jun; ZHANG Mi-lin; WAN Jia-feng; XIA Zhi; LIU Xiao-hui; LIU hui

    2008-01-01

    Catalytic Wet Air Oxidation process is an efficient measure for treatment of wastewater with great strength which is not biodegradable. Heterocatalysts now become the key investigation subject of catalytic wet air oxidation process due to their good stability and easy separation. In the paper, CuO-SnOE-CeO2/γ-Al2O3 catalysts are prepared by impregnation method, with SnO2 as a doping component, CuO as an active component, CeO2 as a structure stabilizer, γ-Al2O3 as a substrate. XPS test is carried out to investigate the effect of Sn on the chemical surrounding of Cu and O element on the catalyst surface and their catalytic activity. It is shown that the right do-ping of Sn can increase Cu+ content on the catalyst surface, as a result the quantity of adsorption oxygen is also increased. It is found that Cu + content on the catalyst surface is one of the primary factors that determin catalytic activity of catalyst through analyzing the catalytic wet air oxidation process of phenol.

  17. Research on Synergy of Combining Electrochemical Oxidation and Catalytic Wet Oxidation%电场效应与催化湿式氧化协同作用研究

    Institute of Scientific and Technical Information of China (English)

    王华; 李光明; 张芳; 黄菊文

    2009-01-01

    A new catalytic wet oxidation fixed-bed reactor combined with three-dimensional electric-field was developed to investigate catalytic wet oxidation, electrochemical oxidation and electroassisted catalytic wet oxidation of the solution containing phenol in the presence of a catalyst Mn-Sn-Sb-3/γ-Al_2O_3 . Good eleetroassisted catalytic wet oxidation efficiency was obtained in the setup for the combination system even at mild conditions ( T = 130℃, po_2 =1.0 MPa) that the phenol conversion and TOC reduction were up to 94.0% and 88.4% after 27 min treatment, respectively. The result also shows that the rate constants of electroassisted catalytic wet oxidation are much higher than that of not only both catalytic wet oxidation and electrochemical oxidation process alone but also additive efficiencies of catalytic wet oxidation and electrochemical oxidation processes, which indicates an apparent synergetic effect between CWO and ECO processes.%在自行研制开发的一套固定床和复合三维电场一体化连续式催化湿式氧化反应器中,采用浸渍法制备的Mn-Sn-Sb-3/γAl_2O_3催化剂,实验研究了苯酚催化湿式氧化、电催化氧化以及电场效应下的催化湿式氧化过程的行为.结果表明,一体化反应器在较低反应温度(T=130℃)和氧分压(Po_2=1.0 MPa)下即可获得相当满意的处理效果,空时仅为27min时苯酚和TOC的去除率就分别可达到94.0%和88.4%.电场效应下的催化湿式氧化协同降解苯酚的反应速率常数大于单独电催化或催化湿式氧化降解苯酚的反应速率常数,而且还大大超过两者之和,电催化氧化对催化湿式氧化工艺存在明显的协同增效作用.

  18. Treatment of aniline by catalytic wet air oxidation: comparative study over CuO/CeO2 and NiO/Al2O3.

    Science.gov (United States)

    Ersöz, Gülin; Atalay, Süheyda

    2012-12-30

    The treatment of aniline by catalytic wet air oxidation (CWAO) was studied in a bubble reactor. The experiments were performed to investigate the effects of catalyst loading, temperature, reaction time, air flow rate, and pressure on aniline removal. The catalytic effects of the prepared nanostructured catalysts, CuO/CeO(2) (10% wt) and NiO/Al(2)O(3) (10% wt), on the CWAO treatment efficiency were also examined and compared. The prepared catalysts seem to be active having an aniline removal of 45.7% with CuO/CeO(2) and 41.9% with NiO/Al(2)O(3). The amount of N(2) formed was approximately the same for both of the catalysts. PMID:23041516

  19. Degradation process analysis of the azo dyes by catalytic wet air oxidation with catalyst CuO/γ-Al2O3.

    Science.gov (United States)

    Hua, Li; Ma, Hongrui; Zhang, Lei

    2013-01-01

    Three azo dyes (Methyl Orange, Direct Brown and Direct Green) were treated by catalytic wet air oxidation (CWAO) with the catalysts CuO/γ-Al(2)O(3) prepared by consecutive impregnation. The relationship of decolorization extent, chemical oxygen demand (COD) removal extent and total organic carbon (TOC) in dye solution were investigated. The results indicated that the CuO/γ-Al(2)O(3) catalyst had excellent catalytic activity in treating azo dyes. Almost 99% of color and 70% of TOC were removed in 2h. The high removal extent of color and TOC indicated that the CWAO obtained perfect decomposition for pollutants. The degradation pathway of azo dyes was analyzed by UV-Vis, FTIR and MS. According to the examined results, the hydroxyl ((·)OH) radicals induced strong oxidizing effects in the target solution and destroyed the chromophoric groups of azo-benzene conjugated of the molecular structure. Considering characteristics of the dye structure, the azo bond (-N=N-) would first be attacked by the hydroxyl radical and other free radicals. With the continuous oxidization and the long reaction time at high temperature, these intermediates could be oxidized to the final oxidation products, such as water and carbon dioxide. PMID:22795071

  20. Post-treatment of biologically treated wastewater containing organic contaminants using a sequence of H2O2 based advanced oxidation processes: photolysis and catalytic wet oxidation.

    Science.gov (United States)

    Rueda-Márquez, J J; Sillanpää, M; Pocostales, P; Acevedo, A; Manzano, M A

    2015-03-15

    In this paper the feasibility of a multi-barrier treatment (MBT) for the regeneration of synthetic industrial wastewater (SIWW) was evaluated. Industrial pollutants (orange II, phenol, 4-chlorophenol and phenanthrene) were added to the effluent of municipal wastewater treatment plant. The proposed MBT begins with a microfiltration membrane pretreatment (MF), followed by hydrogen peroxide photolysis (H2O2/UVC) and finishing, as a polishing step, with catalytic wet peroxide oxidation (CWPO) using granular activated carbon (GAC) at ambient conditions. During the microfiltration step (0.7 μm) the decrease of suspended solids concentration, turbidity and Escherichia coli in treated water were 88, 94 and 99%, respectively. Also, the effluent's transmittance (254 nm) was increased by 14.7%. Removal of more than 99.9% of all added pollutants, mineralization of 63% of organic compounds and complete disinfection of total coliforms were reached during the H2O2/UVC treatment step (H2O2:TOC w/w ratio = 5 and an UVC average dose accumulated by wastewater 8.80 WUVC s cm(-2)). The power and efficiency of the lamp, the water transmittance and photoreactor geometry are taken into account and a new equation to estimate the accumulated dose in water is suggested. Remaining organic pollutants with a higher oxidation state of carbon atoms (+0.47) and toxic concentration of residual H2O2 were present in the effluent of the H2O2/UVC process. After 2.3 min of contact time with GAC at CWPO step, 90 and 100% of total organic carbon and residual H2O2 were removed, respectively. Also, the wastewater toxicity was studied using Vibrio fischeri and Sparus aurata larvae. The MBT operational and maintenance costs (O&M) was estimated to be 0.59 € m(-3). PMID:25600300

  1. Sewage-sludge-derived carbonaceous materials for catalytic wet hydrogen peroxide oxidation of m-cresol in batch and continuous reactors.

    Science.gov (United States)

    Yu, Yang; Wei, Huangzhao; Yu, Li; Wang, Wei; Zhao, Ying; Gu, Bin; Sun, Chenglin

    2016-01-01

    In this study, four sewage-sludge-derived carbonaceous materials (SWs) were evaluated for their catalytic wet hydrogen peroxide oxidation (CWPO) performance of m-cresol in batch reactor and continuous reactor, respectively. The SWs were produced by carbonization (SW); carbonization with the addition of CaO (CaO-SW); HNO3 pretreatment (HNO3-SW) and steam activation (Activated-SW). The properties of SW catalysts were assessed by thermogravimetric analysis, Brunauer-Emmett-Teller, Fourier Transform Infrared Spectroscopy, X-ray Fluorescence, Scanning electron microscopy, energy dispersive X-ray analysis and zeta potential. The results showed that SW treated by HNO3 (HNO3-SW) had a high conversion of m-cresol in batch reactor and continuous reactor, respectively. Under the conditions of batch reaction (Cm-cresol = 100 mg L(-1), CH2O2 = 15.7 mmol L(-1), initial pH=7.0, 0.5 g L(-1) catalyst, 80°C, 180 min adsorption and 210 min oxidation), the conversion of m-cresol reached 100% and total organic carbon removal was 67.1%. It had a high catalytic activity and stability on the treatment of m-cresol in CWPO for more than 1100 h. Furthermore, a possible reaction mechanism for the oxidation of m-cresol to 2-methyl-p-benzoquinone by CWPO was proposed. PMID:26109374

  2. Carbon and nitrogen removal from glucose-glycine melanoidins solution as a model of distillery wastewater by catalytic wet air oxidation.

    Science.gov (United States)

    Phuong Thu, Le; Michèle, Besson

    2016-06-01

    Sugarcane molasses distillery wastewater contains melanoidins, which are dark brown recalcitrant nitrogenous polymer compounds. Studies were carried out in batch mode to evaluate Pt and Ru supported catalysts in the Catalytic Wet Air Oxidation (CWAO) process of a synthetic melanoidins solution, prepared by stoichiometric reaction of glucose with glycine. The addition of a catalyst slightly improved TOC removal compared with the non-catalytic reaction, and especially promoted the conversion of ammonium produced from organically-bound nitrogen in melanoidins to molecular nitrogen and nitrate. The selectivity to N2 attained 89% in the presence of the Pt catalysts in the reaction conditions used (TOC=2200mgL(-1), TN=280mgL(-1), 0.5g catalyst loaded with 3% metal, 210°C, 70bar total air pressure). To avoid leaching of the active metal by organically-bound nitrogen, the reaction was very efficiently performed in a two-step reaction consisting in WAO to convert nitrogen into ammonium, before the introduction of a catalyst. PMID:26900982

  3. 催化湿式氧化预处理造纸黑液%Pretreatment of Black Liquor by Catalytic Wet Air Oxidation

    Institute of Scientific and Technical Information of China (English)

    董振海; 李利敏; 闫海生; 于姗姗; 李秀珍; 毕延文

    2011-01-01

    采用连续式固定床反应器,利用自制稀土类复合金属氧化物催化剂对草浆造纸黑液进行了催化湿式氧化(CWAO)预处理研究.通过正交实验确定了最佳工艺条件为:进水COD 40 800 mg/L,空速0.8h-1,反应温度260℃,反应压力6.5 MPa.在此最佳条件下进行实验,COD去除率达90%.经CWAO工艺处理后,草浆造纸黑液的可生化性显著提高,BOD5/COD由0.11提高至0.62.在1 000 h CWAO连续实验中,自制稀土类复合金属氧化物催化剂显示出较高催化活性和较好的稳定性.%The black liquor from straw pulp paper-making was pretreated by catalytic wet air oxidation (CWAO) in the continuous fixed bed reactor with self-made rare earth oxide catalyst. The optimum process conditions determined by the orthogonal tests are as follows: influent COD 40 800 mg/L,space velocity 0. 8 h-1 .reaction temperature 260℃, reaction pressure 6. 5 Mpa. Under these conditions, the COD removal rate is 90%. The biodegradability of the treated black liquor is significantly improved with BOD5/COD increased from 0. 11 to 0. 62. During 1 000 h of the CWAO continuous experiment, the catalytic activity and stability of the self-made rare earth oxide catalyst are good.

  4. CuZnAl Mixed Oxide Catalyst Prepared from Hydrotalcite-like Precursor for Catalytic Wet Oxidation of Phenol%由类水滑石前驱体制备的CuZnAl复合氧化物催化剂催化湿氧化处理苯酚

    Institute of Scientific and Technical Information of China (English)

    孙颖; 杨民; 窦和瑞; 何雨; 王炜; 孙承林

    2003-01-01

    @@ The efficiency of several noble metals for catalytic wet oxidation (CWO) of various pollutants has been demonstrated[1,2]. However, the noble metals are expensive, affecting greatly the economics of the corresponding process.

  5. APPLICATION OF MAGNETIC CATALYSTS TO THE CATALYTIC WET PEROXIDE OXIDATION (CWPO OF INDUSTRIAL WASTEWATER CONTAINING NON BIODEGRADABLE ORGANIC POLLUTANTS

    Directory of Open Access Journals (Sweden)

    Macarena Munoz

    2014-03-01

    Full Text Available A new ferromagnetic -Al2O3-supported iron catalyst has been prepared and its activity and stability have been compared with those of a previous iron-based conventional catalyst and with the traditional homogeneous Fenton process in the oxidation of chlorophenols. The use of solid catalysts improved significantly the efficiency on the use of H2O2, achieving higher mineralization degrees. The magnetic catalyst led to significantly higher oxidation rates than the conventional one due to the presence of both Fe (II and Fe (III. On the other hand, the use of a catalyst with magnetic properties is of interest, since it allows rapid recovery after treatment using a magnetic field. Moreover, it showed a high stability with fairly low iron leaching (<1% upon CWPO runs. An additional clear advantage of this new catalyst is its easy separation and recovery from the reaction medium by applying an external magnetic field.

  6. Abatement of phenolic mixtures by catalytic wet oxidation enhanced by Fenton's pretreatment: Effect of H2O2 dosage and temperature

    International Nuclear Information System (INIS)

    Catalytic wet oxidation (CWO) of a phenolic mixture containing phenol, o-cresol and p-cresol (500 mg/L on each pollutant) has been carried out using a commercial activated carbon (AC) as catalyst, placed in a continuous three-phase reactor. Total pressure was 16 bar and temperature was 127 deg. C. Pollutant conversion, mineralization, intermediate distribution, and toxicity were measured at the reactor outlet. Under these conditions no detoxification of the inlet effluent was found even at the highest catalyst weight (W) to liquid flow rate (QL) ratio used. On the other hand, some Fenton Runs (FR) have been carried out in a batch way using the same phenolic aqueous mixture previously cited. The concentration of Fe2+ was set to 10 mg/L. The influence of the H2O2 amount (between 10 and 100% of the stoichiometric dose) and temperature (30, 50, and 70 deg. C) on phenols conversion, mineralization, and detoxification have been analyzed. Phenols conversion was near unity at low hydrogen peroxide dosage but mineralization and detoxification achieved an asymptotic value at each temperature conditions. The integration of Fenton reagent as pretreatment of the CWO process remarkably improves the efficiency of the CWO reactor and allows to obtain detoxified effluents at mild temperature conditions and relatively low W/QL values. For a given phenolic mixture a temperature range of 30-50 deg. C in the Fenton pretreatment with a H2O2 dosage between 20 and 40% of the stoichiometric amount required can be proposed

  7. 湿法烟气脱硫环境下亚硫酸钙的非催化氧化%NON-CATALYTIC OXIDATION KINETICS OF CALCIUM SULFITE IN WET LIMESTONE-GYPSUM FGD PROCESS

    Institute of Scientific and Technical Information of China (English)

    杜谦; 吴少华; 朱群益; 秦裕琨

    2003-01-01

    A study on non-catalytic oxidation kinetics of calcium sulfite is presented under typical conditions of wet flue gas desulfurization (FGD)in this paper. A laboratory-scale mechanically stirred tank reactor is used with continuous feed of both gas and liquid phase. The results show that increasing CaSO3 load from a lower value, the reaction rate increases and is limited by solid sulfite dissolution. The oxidation rate limitation is observed at loads exceeding certain concentration. The rate limitation is possibly caused by solid sulfite solubility or oxygen gas-liquid diffusion. The experimental conclusions are useful for design and operation of the holding tank in forced-oxidation wet FGD.

  8. Comparative study of supported CuOx and MnOx catalysts for the catalytic wet air oxidation of β-naphthol

    International Nuclear Information System (INIS)

    Highlights: ► Degradation of β-naphthol was carried out by CWAO and the COD removal was 93.7%. ► Comparative study of supported CuOx and MnOx catalysts was implemented. ► Destruction of β-naphthol was catalyzed by metal oxides supported on nano-TiO2. - Abstract: MnOx/nano-TiO2, MnOx/Al2O3–TiO2 (Al-Ti), CuOx/nano-TiO2 and CuOx/Al-Ti were prepared and their application in catalytic wet air oxidation (CWAO) of β-naphthol were investigated. The catalysts had been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR) measurements. Phases of CuO, Cu2O, CuAl2O4, MnO2 and Mn2O3 could be found on the surface of the aforementioned catalysts. Significant differences in activities were observed among the prepared catalysts. Compared to CuOx/nano-TiO2, the combined action of highly dispersed CuO as well as CuAl2O4 of CuOx/Al-Ti helped to achieve higher activity for the CWAO of β-naphthol, while the Cu2O component lead to lower efficiency of CuOx/nano-TiO2. On the surface of MnOx/nano-TiO2, both the larger amount of highly dispersed MnO2 and the stronger electron transfer between MnO2 and Mn2O3 were helpful to promote the activity for the degradation of β-naphthol. However, the higher amount of bulk MnO2 and the weaker electron transfer for MnOx/Al-Ti were unfavorable to increase its efficiency. Among the four catalysts as-prepared, MnOx/nano-TiO2 was identified the highest activity with 93.7% COD removal.

  9. Inhibiting Wet Oxidation of Ammonia

    Science.gov (United States)

    Onisko, D. B. L.

    1985-01-01

    Simple modification of wet-oxidation process for treating organicwaste reduces loss of fixed nitrogen, potentially valuable byproduct of process. Addition of sufficient sulfuric acid to maintain reaction pH below 3 greatly reduces oxidation of ammonia to free nitrogen. No equipment modification required.

  10. Total catalytic wet oxidation of phenol and its chlorinated derivates with MnO2/CeO2 catalyst in a slurry

    Directory of Open Access Journals (Sweden)

    A. J. Luna

    2009-09-01

    Full Text Available In the present work, a synthetic effluent of phenol was treated by means of a total oxidation process-Catalyzed Wet Oxidation (CWO. A mixed oxide of Mn-Ce (7:3, the catalyst, was synthesized by co-precipitation from an aqueous solution of MnCl2 and CeCl3 in a basic medium. The mixed oxide, MnO2/CeO2, was characterized and used in the oxidation of phenol in a slurry reactor in the temperature range of 80-130ºC and pressure of 2.04-4.76 MPa. A phenol solution containing 2.4-dichlorophenol and 2.4-dichlorophenoxyacetic acid was also degraded with good results. A lumped kinetic model, with two parallel reaction steps, fits precisely with the integrated equation and the experimental data. The kinetic parameters obtained are in agreement with the Arrhenius equation. The activation energies were determined to be 38.4 for the total oxidation and 53.4 kJ/mol for the organic acids formed.

  11. Coal combustion by wet oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Bettinger, J.A.; Lamparter, R.A.; McDowell, D.C.

    1980-11-15

    The combustion of coal by wet oxidation was studied by the Center for Waste Management Programs, of Michigan Technological University. In wet oxidation a combustible material, such as coal, is reacted with oxygen in the presence of liquid water. The reaction is typically carried out in the range of 204/sup 0/C (400/sup 0/F) to 353/sup 0/C (650/sup 0/F) with sufficient pressure to maintain the water present in the liquid state, and provide the partial pressure of oxygen in the gas phase necessary to carry out the reaction. Experimental studies to explore the key reaction parameters of temperature, time, oxidant, catalyst, coal type, and mesh size were conducted by running batch tests in a one-gallon stirred autoclave. The factors exhibiting the greatest effect on the extent of reaction were temperature and residence time. The effect of temperature was studied from 204/sup 0/C (400/sup 0/F) to 260/sup 0/C (500/sup 0/F) with a residence time from 600 to 3600 seconds. From this data, the reaction activation energy of 2.7 x 10/sup 4/ calories per mole was determined for a high-volatile-A-Bituminous type coal. The reaction rate constant may be determined at any temperature from the activation energy using the Arrhenius equation. Additional data were generated on the effect of mesh size and different coal types. A sample of peat was also tested. Two catalysts were evaluated, and their effects on reaction rate presented in the report. In addition to the high temperature combustion, low temperature desulfurization is discussed. Desulfurization can improve low grade coal to be used in conventional combustion methods. It was found that 90% of the sulfur can be removed from the coal by wet oxidation with the carbon untouched. Further desulfurization studies are indicated.

  12. Catalytic ammonia oxidation to nitrogen (I) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

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

  13. Mechanisms of wet oxidation by hydrogen peroxide

    International Nuclear Information System (INIS)

    A research programme is currently under way at BNL and MEL to investigate the possible use of Hydrogen Peroxide with metal ion catalysts as a wet oxidation treatment system for CEGB organic radioactive wastes. The published literature relating to the kinetics and mechanism of oxidation and decomposition reactions of hydrogen peroxide is reviewed and the links with practical waste management by wet oxidation are examined. Alternative wet oxidation systems are described and the similarities to the CEGB research effort are noted. (author)

  14. Wet oxidation of a spacecraft model waste

    Science.gov (United States)

    Johnson, C. C.; Wydeven, T.

    1985-01-01

    Wet oxidation was used to oxidize a spacecraft model waste under different oxidation conditions. The variables studied were pressure, temperature, duration of oxidation, and the use of one homogeneous and three heterogeneous catalysts. Emphasis is placed on the final oxidation state of carbon and nitrogen since these are the two major components of the spacecraft model waste and two important plant nutrients.

  15. Electro Catalytic Oxidation (ECO) Operation

    Energy Technology Data Exchange (ETDEWEB)

    Morgan Jones

    2011-03-31

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

  16. Advanced methods for the treatment of organic aqueous wastes: wet air oxidation and wet peroxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Debellefontaine, Hubert; Chakchouk, Mehrez; Foussard, Jean Noel [Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France). Dept. de Genie des Procedes Industriels; Tissot, Daniel; Striolo, Phillipe [IDE Environnement S.A., Toulouse (France)

    1993-12-31

    There is a growing concern about the problems of wastes elimination. Various oxidation techniques are suited for elimination of organic aqueous wastes, however, because of the environmental drawbacks of incineration, liquid phase oxidation should be preferred. `Wet Air Oxidation` and `Wet Peroxide Oxidation`are alternative processes which are discussed in this paper. 17 refs., 13 figs., 4 tabs.

  17. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  18. Wet Chemistry of Spinel Iron oxide Particles

    OpenAIRE

    Jolivet, J.; Chanéac, C.; Prené, P.; Vayssières, L.; Tronc, E.

    1997-01-01

    Various properties of spinel iron oxide nanograins are reviewed, illustrating the broad possibilities of wet chemistry for tailoring materials for a wide range of utilizations, from catalysis and sensors to cast magnetic materials.

  19. Research Progress on Catalyst of Catalytic Wet Air Oxidation for Phenol Wastewater%催化湿式氧化含酚废水催化剂的研究进展

    Institute of Scientific and Technical Information of China (English)

    李荣; 段大勇

    2015-01-01

    Catalytic wet air oxidation ( CWAO ) technology is an effective technology for phenol wastewater, developing and selecting suitable catalyst is a key factor of CWAO. Active components were briefly introduced and CWAO catalyst for phenol wastewater treatment was carried out. It was specified that selecting the best combination of suitable active component and carrier of CWAO catalyst can improve the efficiency of phenol degradation, developing the catalyst with high activity, stability and cheap characteristics was the development direction of CWAO for phenol wastewater treatment.%催化湿式氧化技术是处理含酚废水的有效技术,此技术的关键是合适催化剂的研制和选用。本文对催化湿式氧化含酚废水催化剂的活性组分、载体等情况进行了综述,并指出选用最佳活性组分和载体的组合能够提高催化剂对苯酚的降解效率,研发高活性、高稳定性及廉价的催化剂是催化湿式氧化含酚废水的发展方向。

  20. Wet Oxidation of PVA-Containing Desizing Wastewater

    Institute of Scientific and Technical Information of China (English)

    雷乐成; 汪大翬

    2000-01-01

    Polyvinyl alcohol (PVA)-containing desizing wastewater was treated by various wet oxidation methods.Parameters such as reaction temperature, initial solution pH, and the dosage of H2O2 were investigated in terms of chemical oxygen demand (CODcr) and total organic carbon (TOC) removal rate. Up to 90% of the initial CODcr was removed by wet air oxidation(WAO) at 270℃ with stoichiometric oxygen supply, while at temperature of 200℃, the CODcr removal rate was found to be 80%. Similar results were obtained by Promoted WAO (PWAO) and wet peroxide oxidation(WPO) at a lower temperature of 150℃. Reaction temperature was found to have a significant effect on the oxidation performance for all the methods. Initial solution pH was observed to play a significant role in PWAO and WPO where H2O2 was employed. Comparison of WAO, CWAO(catalytic wet air oxidation), PWAO and WPO shows that the rate of CODcr removal increases in the order: WAO, CWAO, PWAO and WPO.

  1. Development studies of a novel wet oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, T.W.; Dhooge, P.M. [Delphi Research, Inc., Albuquerque, NM (United States)

    1995-10-01

    Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides. These materials are often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. Incineration and similar combustive processes do not appear to be viable options for treatment of these waste streams due to various considerations. The objective of this project is to develop a novel catalytic wet oxidation process for the treatment of multi-component wastes. The DETOX process uses a unique combination of metal catalysts to increase the rate of oxidation of organic materials.

  2. Catalytic Chemistry on Oxide Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-29

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

  3. Degradation of phenol via wet-air oxidation over CuO/CeO2-ZrO2 nanocatalyst synthesized employing ultrasound energy: physicochemical characterization and catalytic performance.

    Science.gov (United States)

    Parvas, Mohsen; Haghighi, Mohammad; Allahyari, Somaiyeh

    2014-01-01

    Catalytic wet air oxidation (CWAO) of phenol was carried out under atmospheric pressure of oxygen at 160 degrees C in a stirred batch reactor over copper catalysts supported by CeO2-ZrO2. The copper with different loadings were impregnated over the composite support by a sonication process. The catalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), Brunauer-Emmett-Teller (BET) specific surface area and Fourier-transformed infrared analyses. Characteristic peaks attributed to copper were not found in XRD patterns even at high loadings, but based on EDX results, the existence of copper particles was confirmed. It means that sonochemical synthesis method even at high loadings produced small copper particles with low crystallinity and excellent dispersion over the CeO2-ZrO2 composite. FESEM micrographs indicated just slight enhancement in particle size at high loadings of Cu. Blank CWAO experiments illustrated low conversion of phenol using bare CeO2-ZrO2 support. Although some agglomeration of particles was found at high loadings of copper but owning to the fact that almost all ZrO2 particles incorporated into the CeO2 lattice at high contents of Cu, catalyst activity not only did not decrease but also the phenol conversion reached to the higher values. The optimal catalyst loading for phenol degradation was found to be 9 g/l. Complete conversion of phenol was achieved using CuO/CeO2-ZrO2 in 9 g/l catalyst loading with initial phenol concentration of 1000 ppm after 3 h of reaction. PMID:24701909

  4. Conference: the wet catalytic oxidation, a technology for the removal of organic pollutants in industrial waters; Conference: l'oxydation voie humide catalytique, une technologie pour l'elimination des polluants organiques dans les eaux industrielles

    Energy Technology Data Exchange (ETDEWEB)

    Besson, M. [Institut de recherches sur la catalyse - CNRS, 2 avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

    2004-07-01

    In this conference, it is taken stock on the use of catalysts in the wet oxidation process. Supported (TiO{sub 2}, ZrO{sub 2}....) heterogeneous metallic catalysts (Pt, Ru...) are particularly studied. It is shown that this type of catalysts can answer to the required characteristics: activity for the removal of organic matter, lack of active metal leaching in aqueous acid medium, no deactivation...Examples are given. (O.M.)

  5. Post-treatment of refinery wastewater effluent using a combination of AOPs (H2O2 photolysis and catalytic wet peroxide oxidation) for possible water reuse. Comparison of low and medium pressure lamp performance.

    Science.gov (United States)

    Rueda-Márquez, J J; Levchuk, I; Salcedo, I; Acevedo-Merino, A; Manzano, M A

    2016-03-15

    The main aim of this work was to study the feasibility of multi-barrier treatment (MBT) consisting of filtration, hydrogen peroxide photolysis (H2O2/UVC) and catalytic wet peroxide oxidation (CWPO) for post-treatment of petroleum refinery effluent. Also the possibility of water reuse or safe discharge was considered. The performance of MBT using medium (MP) and low (LP) pressure lamps was compared as well as operation and maintenance (O&M) cost. Decomposition of organic compounds was followed by means of gas chromatography-mass spectrometry (GC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analysis. After filtration step (25 μm) turbidity and concentration of suspended solids decreased by 92% and 80%, respectively. During H2O2/UVC process with LP lamp at optimal conditions (H2O2:TOC ratio 8 and UVC dose received by water 5.28 WUVC s cm(-2)) removal of phenolic compounds, TOC and COD was 100%, 52.3% and 84.3%, respectively. Complete elimination of phenolic compounds, 47.6% of TOC and 91% of COD was achieved during H2O2/UVC process with MP lamp at optimal conditions (H2O2:TOC ratio 5, UVC dose received by water 6.57 WUVC s cm(-2)). In order to compare performance of H2O2/UVC treatment with different experimental set up, the UVC dose required for removal of mg L(-1) of COD was suggested as a parameter and successfully applied. The hydrophilicity of H2O2/UVC effluent significantly increased which in turn enhanced the oxidation of organic compounds during CWPO step. After H2O2/UVC treatment with LP and MP lamps residual H2O2 concentration was 160 mg L(-1) and 96.5 mg L(-1), respectively. Remaining H2O2 was fully consumed during subsequent CWPO step (6 and 3.5 min of contact time for LP and MP, respectively). Total TOC and COD removal after MBT was 94.7% and 92.2% (using LP lamp) and 89.6% and 95%, (using MP lamp), respectively. The O&M cost for MBT with LP lamp was estimated to be 0.44 € m(-3) while with MP lamp it was nearly five

  6. Wet oxidation processes for water pollution remediation

    OpenAIRE

    García Molina, Verónica

    2006-01-01

    [eng] The main objective of this work was to test the efficiency of wet oxidation processes when treating several types of aqueous wastes. On one side its performance for the abatement of chloro-organic aromatic toxic pollutants, such as 4-chlorophenol and 2,4-dichlorophenol has been studied. On the other hand, wastewater from pulp and paper mills, which has been reported to be an indirect source of entry of chlorophenols in the aquatic environment, has been investigated. More in detail, it h...

  7. Development of Pillared Clays for Wet Hydrogen Peroxide Oxidation of Phenol and Its Application in the Posttreatment of Coffee Wastewater

    Directory of Open Access Journals (Sweden)

    Nancy R. Sanabria

    2012-01-01

    Full Text Available This paper focuses on the use of pillared clays as catalysts for the Fenton-like advanced oxidation, specifically wet hydrogen peroxide catalytic oxidation (WHPCO. This paper discusses the limitations on the application of a homogeneous Fenton system, development of solid catalysts for the oxidation of phenol, advances in the synthesis of pillared clays, and their potential application as catalysts for phenol oxidation. Finally, it analyzes the use of pillared clays as heterogeneous Fenton-like catalysts for a real wastewater treatment, emphasizing the oxidation of phenolic compounds present in coffee wastewater. Typically, the wet hydrogen peroxide catalytic oxidation in a real effluent system is used as pretreatment, prior to biological treatment. In the specific case of coffee wet processing wastewater, catalytic oxidation with pillared bentonite with Al-Fe is performed to supplement the biological treatment, that is, as a posttreatment system. According to the results of catalytic activity of pillared bentonite with Al-Fe for oxidation of coffee processing wastewater (56% phenolic compounds conversion, 40% selectivity towards CO2, and high stability of active phase, catalytic wet hydrogen peroxide oxidation emerges as a viable alternative for management of this type of effluent.

  8. Development studies for a novel wet oxidation process

    International Nuclear Information System (INIS)

    A catalytic wet oxidation process (DETOX), which uses an acidic iron solution to oxidize organic compounds to carbon dioxide, water, and other simple products, was investigated as a potential method for the treatment of multicomponent hazardous and mixed wastes. The organic compounds picric acid, poly(vinyl chloride), tetrachlorothiophene, pentachloropyridine, Aroclor 1260 (a polychlorinated biphenyl), and hexachlorobenzene were oxidized in 125 ml reaction vessels. The metals arsenic, barium, beryllium, cadmium, cerium (as a surrogate for plutonium), chromium, lead, mercury, neodymium (as a surrogate for uranium), nickel, and vanadium were tested in the DETOX solution. Barium, beryllium, cerium, chromium, mercury, neodymium, nickel, and vanadium were all found to be very soluble (>100 g/l) in the DETOX chloride-based solution. Arsenic, barium, cadmium, and lead solubilities were lower. Lead could be selectively precipitated from the DETOX solution. Chromium(VI) was reduced to relatively non-toxic chromium(III) by the solution. Six soils were contaminated with arsenic, barium, beryllium, chromium, lead, and neodymium oxides at approximately 0.1% by weight, and benzene, trichloroethene, mineral oil, and Aroclor 1260 at approximately 5% by weight total, and 5.g amounts treated with the DETOX solution in unstirred 125. ml reaction bombs. It is felt that soil treatment in a properly designed system is entirely possible despite incomplete oxidation of the less volatile organic materials in these unstirred tests

  9. Development studies for a novel wet oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Dhooge, P.M.; Hakim, L.B.

    1994-01-01

    A catalytic wet oxidation process (DETOX), which uses an acidic iron solution to oxidize organic compounds to carbon dioxide, water, and other simple products, was investigated as a potential method for the treatment of multicomponent hazardous and mixed wastes. The organic compounds picric acid, poly(vinyl chloride), tetrachlorothiophene, pentachloropyridine, Aroclor 1260 (a polychlorinated biphenyl), and hexachlorobenzene were oxidized in 125 ml reaction vessels. The metals arsenic, barium, beryllium, cadmium, cerium (as a surrogate for plutonium), chromium, lead, mercury, neodymium (as a surrogate for uranium), nickel, and vanadium were tested in the DETOX solution. Barium, beryllium, cerium, chromium, mercury, neodymium, nickel, and vanadium were all found to be very soluble (>100 g/l) in the DETOX chloride-based solution. Arsenic, barium, cadmium, and lead solubilities were lower. Lead could be selectively precipitated from the DETOX solution. Chromium(VI) was reduced to relatively non-toxic chromium(III) by the solution. Six soils were contaminated with arsenic, barium, beryllium, chromium, lead, and neodymium oxides at approximately 0.1% by weight, and benzene, trichloroethene, mineral oil, and Aroclor 1260 at approximately 5% by weight total, and 5.g amounts treated with the DETOX solution in unstirred 125. ml reaction bombs. It is felt that soil treatment in a properly designed system is entirely possible despite incomplete oxidation of the less volatile organic materials in these unstirred tests.

  10. The use of catalyst to enhance the wet oxidation process.

    Science.gov (United States)

    Maugans, C; Kumfer, B

    2007-01-01

    Wet oxidation tests were performed on two pure compound streams: acetic acid and ammonia; and on two wastewater streams: acrylic acid wastewater and sulphide laden spent caustic. Test results showed that Mn/Ce and Pt/TiO2 were effective catalysts that greatly enhanced acetic acid, ammonia and acrylic acid wastewater destruction. However, the Mn/Ce catalyst performance appears to be inhibited by concentrated salts dissolved in solution. This could limit the applicability of this catalyst for the treatment of brackish wastewaters. Zr, Ce and Ce nanoparticles were also shown to exhibit some catalytic activity, however not to the extent of the Mn/Ce and the Pt/TiO2. PMID:17674847

  11. Catalytic oxidation of dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-10

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

  12. Biomimetic, Catalytic Oxidation in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    Shun-lchi Murahashi

    2005-01-01

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

  13. Degradation of Bagasse Alkaline Lignin by Catalytic Wet Air Oxidation with Five Catalysts%催化剂对甘蔗渣碱木质素催化湿空气氧化降解的催化作用

    Institute of Scientific and Technical Information of China (English)

    姚向荣; 詹怀宇; 周生飞

    2011-01-01

    In this paper, bagasse alkaline lignin was degraded by Catalytic Wet Air Oxidation (CWAO) with five different catalysts. The results showed that the main degradation products were; p-hydroxybenzaldehyde, vanillin, syringaldehyde, syringic acid, vanillic acid and acetosyringone. The concentration of aromatic substances increased when the reaction time increased. Catalysts had a significant effect on the concentration of aromatic substances. Using CO2O3 as catalyst, the concentration of vanillin, syringaldehyde and acetosyringone were 400.2 mg/L, 351.4 mg/L, and 248.7 mg/L respectively, and the concentration of vanillin increased 82.6% comparing to no catalyst was used. Using AQ as catalyst, the concentration of vanillin was 344. 9 mg/L which was 1. 5 times of that without using catalyst. Using Co2O3, CuSO4, MnO2, AQ, Fe2O3 as catalysts, the total concentrations of phenolic aldehyde compounds were 1696 mg/L, 1658 mg/L, 1584 mg/ L, 1347 mg/L and 1250 mg/L respectively,which explained that using Co2O3 as the catalyst was the best, and CuSO4 and MnO2 were the next, the catalysts of AQ and Fe2O3 only contributed to produce several kinds of phenolic aldehyde compounds with small molecules.%选取5种不同的催化剂对甘蔗渣碱木质素进行了催化湿空气氧化降解。结果表明,甘蔗渣碱木质素催化湿空气氧化降解的主要产物为对羟基苯甲醛、香草醛、丁香醛、丁香酸、香草酸和乙酰丁香酮;在实验条件下,反应时间对催化剂催化效果的影响较大,随着反应时间的延长,大部分小分子酚醛类化合物的浓度逐渐升高;使用催化剂能较大幅度地提高小分子酚醛类化合物的浓度。以Co2O3为催化剂,丁香醛、乙酰丁香酮、香草醛的浓度分别为400.2 mg/L、351.4 mg/L 248.7 mg/L,与未添加催化剂相比较,香草醛浓度提高了 82.6%;当以AQ为催化剂时,香草醛浓度为344.9mg/L,与空白样相比其浓度提高了1.5倍以上。

  14. Catalytic oxidation of industrial organic solvent vapors.

    Science.gov (United States)

    Tzortzatou, Katerina; Grigoropoulou, Eleni

    2010-01-01

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

  15. Electrochemical promotion of sulfur dioxide catalytic oxidation

    DEFF Research Database (Denmark)

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

    2000-01-01

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

  16. Catalytic oxidations by vanadium complexes

    OpenAIRE

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

    2003-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    Jinyan Hu; Wei Chu; Limin Shi

    2008-01-01

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

  18. Specific features of aluminum nanoparticle water and wet air oxidation

    International Nuclear Information System (INIS)

    The oxidation processes of the electrically exploded aluminum nanopowders in water and in wet air are examined in the paper. The morphology of the intermediate reaction products of aluminum oxidation has been studied using the transmission electron microscopy. It was shown that the aluminum nanopowder water oxidation causes the formation of the hollow spheres with mesoporous boehmite nanosheets coating. The wedge-like bayerite particles are formed during aluminum nanopowder wet air oxidation

  19. Formaldehyde degradation by catalytic oxidation.

    OpenAIRE

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

    1981-01-01

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

  20. Development of Pillared Clays for Wet Hydrogen Peroxide Oxidation of Phenol and Its Application in the Posttreatment of Coffee Wastewater

    OpenAIRE

    Nancy R. Sanabria; Rafael Molina; Sonia Moreno

    2012-01-01

    This paper focuses on the use of pillared clays as catalysts for the Fenton-like advanced oxidation, specifically wet hydrogen peroxide catalytic oxidation (WHPCO). This paper discusses the limitations on the application of a homogeneous Fenton system, development of solid catalysts for the oxidation of phenol, advances in the synthesis of pillared clays, and their potential application as catalysts for phenol oxidation. Finally, it analyzes the use of pillared clays as heterogeneous Fenton-l...

  1. Catalytic wet peroxidation of pyridine bearing wastewater by cerium supported SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Subbaramaiah, V. [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India); Srivastava, Vimal Chandra, E-mail: vimalcsr@yahoo.co.in [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India); Mall, Indra Deo [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India)

    2013-03-15

    Highlights: ► Cerium supported SBA-15 (Ce/SBA-15) synthesized by two-step synthesis. ► Characterization of Ce/SBA-15 by FTIR, XRD and BET surface area. ► Catalytic peroxidation of pyridine by Ce/SBA-15. ► Optimization of parameters like catalyst dose, H{sub 2}O{sub 2} dose, initial concentration and temperature. ► Catalyst reusability and leaching study performed. -- Abstract: Cerium supported SBA-15 (Ce/SBA-15) was synthesized by two-step synthesis method in acidic medium. It was further characterized by various characterization techniques such as X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy and N{sub 2} adsorption–desorption pore size distribution analysis. The Ce/SBA-15 showed highly ordered meso-structure with pore diameter ≈ 70–100 A and pore volume ≈ 0.025 cm{sup 3}/g. Ce/SBA-15 was further evaluated as a catalyst for the oxidation of highly toxic and non-biodegradable material, pyridine, by catalytic wet-peroxidation method. The effects of various operating parameters such as catalyst dose (0.5–6 g/l), stoichiometric ratio of H{sub 2}O{sub 2}/pyridine (1–6), initial pyridine concentration (50–800 mg/l) and temperature (313–358 K) have been evaluated and optimized. Ce/SBA-15 showed stable performance during reuse for six cycles with negligible cerium leaching. Kinetic and thermodynamic parameters and operation cost have also been determined.

  2. Low-temperature catalytic gasification of wet industrial wastes

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D C; Neuenschwander, G G; Baker, E G; Sealock, Jr, L J; Butner, R S

    1991-04-01

    Bench-scale reactor tests are in progress at Pacific Northwest Laboratory to develop a low-temperature, catalytic gasification system. The system, licensed under the trade name Thermochemical Environmental Energy System (TEES{reg sign}), is designed for treating a wide variety of feedstocks ranging from dilute organics in water to waste sludges from food processing. This report describes a test program which used a continuous-feed tubular reactor. This test program is an intermediate stage in the process development. The reactor is a laboratory-scale version of the commercial concept as currently envisioned by the process developers. An energy benefit and economic analysis was also completed on the process. Four conceptual commercial installations of the TEES process were evaluated for three food processing applications and one organic chemical manufacturing application. Net energy production (medium-Btu gas) was achieved in all four cases. The organic chemical application was found to be economically attractive in the present situation. Based on sensitivity studies included in the analysis, the three food processing cases will likely become attractive in the near future as waste disposal regulations tighten and disposal costs increase. 21 refs., 2 figs., 9 tabs.

  3. Catalytic and surface oxidation processes on transition metal surfaces

    OpenAIRE

    Jaatinen, Sampsa

    2007-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

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

  5. 1 - Aromatization of n-hexane and natural gasoline over ZSM-5 zeolite, 2- Wet catalytic oxidation of phenol on fixed bed of active carbon; 1 - Aromatisation de n-hexane et d'essence sur zeolithe ZSM-5, 2 - Oxydation catalytique en voie humide du phenol sur charbon actif

    Energy Technology Data Exchange (ETDEWEB)

    Suwanprasop, S.

    2005-04-15

    I - The production of aromatic hydrocarbons from n-hexane and natural gasoline over Pd loaded ZSM-5 zeolite in a tubular reactor was achieved under the suitable conditions at 400 deg. C, and 0.4 ml/min reactant feeding rate, employing ZSM-5 (0.5% Pd content) as a catalyst. Under these conditions, n-hexane and natural gasoline conversions were found to be 99.7% and 94.3%, respectively (with respective aromatic selectivity of 92.3% and 92.6%). II - Wet catalytic air oxidation of phenol over a commercial active carbon was studied in a three phase fixed bed reactor under mild temperature and oxygen partial pressure. Exit phenol concentration, COD, and intermediates were analysed. Oxidation of phenol was significantly improved when increasing operating temperature, oxygen partial pressure, and liquid space time, while up or down flow modes had only marginal effect. A complete model involving intrinsic kinetics and all mass transfer limitations gave convenient reactor simulation. (author)

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  7. Wet-air oxidation cleans up black wastewater

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    Sterling Organics produces the analgesic paracetamol (acetaminophen) at its Dudley, England, plant. The wastewater from the batch process contains intermediates such as para-aminophenol (PAP) and byproducts such as thiosulfates, sulfites and sulfides. To stay ahead of increasingly strict environmental legislation, Sterling Organics installed a wet-air oxidation system at the Dudley facility in August 1992. The system is made by Zimpro Environmental Inc. (Rothschild, Wis.). Zimpro's wet-air oxidation system finds a way around the limitations of purely chemical or physical processes. In the process, compressed air at elevated temperature and pressure oxidizes the process intermediates and byproducts and removes the color from the wastewater.

  8. The study of leachate treatment by using three advanced oxidation process based wet air oxidation

    OpenAIRE

    Mokhtari Mehdi; Ebrahimi Asghar; Ehrampoush Mohammad Hassan; Karimi Behroz

    2013-01-01

    Abstract Wet air oxidation is regarded as appropriate options for wastewater treatment with average organic compounds. The general purpose of this research is to determine the efficiency of three wet air oxidation methods, wet oxidation with hydrogen peroxide and absorption with activated carbon in removing organic matter and nitrogenous compounds from Isfahan's urban leachate. A leachate sample with the volume of 1.5 liters entered into a steel reactor with the volume of three liters and was...

  9. The Study of LeachateTreatment by Using Three Advanced Oxidation Process Based Wet air Oxidation

    OpenAIRE

    Behroz Karimi; Mohammad Hassan Ehrampoush; Asghar Ebrahimi; Mehdi Mokhtari

    2013-01-01

    Wet air oxidation is regarded as appropriate options for wastewater treatment with average organic compounds. The general purpose of this research is to determine the efficiency of three wet air oxidation methods, wet oxidation with hydrogen peroxide and absorption with activated carbon in removing organic matter and nitrogenous compounds from Isfahan's urban leachate. A leachate sample with the volume of 1.5 liters entered into a steel reactor with the volume of three liters and was put unde...

  10. Pilot Testing of Mercury Oxidation Catalysts for Upstream of Wet FGD Systems

    Energy Technology Data Exchange (ETDEWEB)

    Gary Blythe; Conor Braman; Katherine Dombrowski; Tom Machalek

    2010-12-31

    This document is the final technical report for Cooperative Agreement DE-FC26-04NT41992, 'Pilot Testing of Mercury Oxidation Catalysts for Upstream of Wet FGD Systems,' which was conducted over the time-period January 1, 2004 through December 31, 2010. The objective of this project has been to demonstrate at pilot scale the use of solid catalysts and/or fixed-structure mercury sorbents to promote the removal of total mercury and oxidation of elemental mercury in flue gas from coal combustion, followed by wet flue gas desulfurization (FGD) to remove the oxidized mercury at high efficiency. The project was co-funded by the U.S. DOE National Energy Technology Laboratory (DOE-NETL), EPRI, Great River Energy (GRE), TXU Energy (now called Luminant), Southern Company, Salt River Project (SRP) and Duke Energy. URS Group was the prime contractor. The mercury control process under development uses fixed-structure sorbents and/or catalysts to promote the removal of total mercury and/or oxidation of elemental mercury in the flue gas from coal-fired power plants that have wet lime or limestone FGD systems. Oxidized mercury not adsorbed is removed in the wet FGD absorbers and leaves with the byproducts from the FGD system. The project has tested candidate materials at pilot scale and in a commercial form, to provide engineering data for future full-scale designs. Pilot-scale catalytic oxidation tests have been completed for periods of approximately 14 to19 months at three sites, with an additional round of pilot-scale fixed-structure sorbent tests being conducted at one of those sites. Additionally, pilot-scale wet FGD tests have been conducted downstream of mercury oxidation catalysts at a total of four sites. The sites include the two of three sites from this project and two sites where catalytic oxidation pilot testing was conducted as part of a previous DOE-NETL project. Pilot-scale wet FGD tests were also conducted at a fifth site, but with no catalyst or fixed

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

    Science.gov (United States)

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

    2015-12-30

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

  12. Kinetics of wet peroxide oxidation of phenol with a gold/activated carbon catalyst

    OpenAIRE

    Domínguez, Carmen M.; Quintanilla, Asunción; Casas, José Antonio; Rodríguez, Juan José

    2014-01-01

    Gold nanoparticles supported on activated carbon (Au/AC) have been tested in catalytic wet peroxide oxidation using phenol as target pollutant. In the current work, the effect of several operating conditions, including initial pH (3.5–10.5), catalyst load (0–6 g/L), initial phenol concentration (0.1–5 g/L), hydrogen peroxide dose (4–100% of the theoretical stoichiometric amount) and reaction temperature (50–80 °C) has been investigated. The results show that the Au/AC catalyst would be useful...

  13. Oxidation and wet wear of silicon carbide

    OpenAIRE

    Presser, Volker

    2009-01-01

    Siliziumkarbid (SiC) ist sowohl die wohl bedeutendste Nichtoxidkeramik aber auch als Halbleiter ein vielversprechendes Material. Gaskorrosion in Gegenwart von Sauerstoff führt dabei als einzige feste Phase zu Bildung von SiO2 (passive Oxidation). Hierbei spielen jedoch viele Einflussfaktoren eine wichtige Rolle, wie zum Beispiel Porosität, Sinteradditive, Verunreinigungen, die kristallographische Orientierung, vorhergehende Oberflächenbehandlung und die chemische Zusammensetzung der oxidie...

  14. Optimization of wet oxidation pretreatment of wheat straw

    DEFF Research Database (Denmark)

    Schmidt, A.S.; Thomsen, A.B.

    1998-01-01

    The wet oxidation process (water; oxygen and elevated temperature) was investigated under alkaline conditions for fractionation of hemicellulose, cellulose, and lignin from wheat straw. At higher temperature and longer reaction time, a purified cellulose fraction (69% w/w) was produced with high...

  15. Catalytic partial oxidation of pyrolysis oils

    Science.gov (United States)

    Rennard, David Carl

    2009-12-01

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

  16. Fe salts as catalyst for the wet oxidation of o-chlorophenol

    Institute of Scientific and Technical Information of China (English)

    XU Xin-hua; HE Ping; JIN Jian; HAO Zhi-wei

    2005-01-01

    Catalytic wet air oxidation (CWAO) of o-chlorophenol in wastewater was studied in a stainless steel autoclave using four different Fe catalysts in the temperature range of 100-200 ℃. Experimental results showed that high rate of o-chlorophenol and CODcr (Chemical Oxygen Demand, mg/L) removal by CWAO was obtained at relatively low temperature and pressure. The catalysts Fe2(SO4)3, FeSO4, Fe2O3 and FeCl3 all exhibited high catalytic activity. More than 93.7% of the initial CODCr and nearly100% of o-chlorophenol were removed at 150 ℃ after 150 min with FeSO4 as catalyst. The CWAO of o-chlorophenol was found to be pseudo-first order reaction with respect to o-chlorophenol, with activation energy of 75.56 k J/mol in the temperature range of100-175 ℃.

  17. Wet oxidation as a waste treatment in closed systems

    Science.gov (United States)

    Onisko, B. L.; Wydeven, T.

    1981-01-01

    The chemistry of the wet oxidation process has been investigated in relation to production of plant nutrients from plant and human waste materials as required for a closed life-support system. Hydroponically grown lettuce plants were used as a model plant waste and oxygen gas was used as oxidant. Organic nitrogen content was decreased 88-100% depending on feed material. Production of ammonia and nitrogen gas account for all of the observed decrease in organic nitrogen content. No nitrous oxide (N2O) was detected. The implications of these results for closed life-support systems are discussed.

  18. Wet Oxidation as a Waste Treatment Method in Closed Systems

    Science.gov (United States)

    Onisko, B. L.; Wydeven, T.

    1982-01-01

    The chemistry of the wet oxidation process was investigated in relation to production of plant nutrients from plant and human waste materials as required for a closed life support system. Hydroponically grown lettuce plants were used as a model plant waste, and oxygen gas was used as an oxidant. Organic nitrogen content was decreased 88-100%, depending on feed material. Production of ammonia and nitrogen gas accounted for all of the observed decrease in organic nitrogen content. No nitrous oxide (N2O) was detected. The implications of these results for closed life support systems are discussed.

  19. Wet oxidation of real coke wastewater containing high thiocyanate concentration.

    Science.gov (United States)

    Oulego, Paula; Collado, Sergio; Garrido, Laura; Laca, Adriana; Rendueles, Manuel; Díaz, Mario

    2014-01-01

    Coke wastewaters, in particular those with high thiocyanate concentrations, represent an important environmental problem because of their very low biodegradability. In this work, the treatment by wet oxidation of real coke wastewaters containing concentrations of thiocyanate above 17 mM has been studied in a 1-L semi-batch reactor at temperatures between 453 and 493 K, with total oxygen pressures in the range of 2.0-8.0 MPa. A positive effect of the matrix of real coke wastewater was observed, resulting in faster thiocyanate degradation than was obtained with synthetic wastewaters. Besides, the effect of oxygen concentration and temperature on thiocyanate wet oxidation was more noticeable in real effluents than in synthetic wastewaters containing only thiocyanate. It was also observed that the degree of mineralization of the matrix organic compounds was higher when the initial thiocyanate concentration increased. Taking into account the experimental data, kinetic models were obtained, and a mechanism implying free radicals was proposed for thiocyanate oxidation in the matrix considered. In all cases, sulphate, carbonates and ammonium were identified as the main reaction products of thiocyanate wet oxidation. PMID:24269931

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

    OpenAIRE

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

    1989-01-01

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

  1. Wet Electrolytic Oxidation of Organics and Application for Sludge Treatment

    Science.gov (United States)

    Serikawa, Roberto M.

    Wet electrolytic oxidation (WEO) is electrochemical oxidation conducted at subcritical water temperature and pressure. Under these conditions, the electrolytic reaction of water is very different from the reaction usually seen in water electrolysis. Electrolysis of an aqueous NaCl solution at 250°C proceeds without the evolution of any oxygen, chlorine or even hydrogen. Rapid oxidation of organics to CO2 occurs in WEO with the production of hydrogen. Further addition of an oxidizer enhances the electrochemical oxidation of organics with the suppression of hydrogen evolution. AOX compounds found in usual electrooxidation are not formed in WEO treatment. When WEO is applied to sludge treatment, colors are drastically reduced and there is an increase in the yield of organic acids. The biodegradability increases by up to 50% and the treated water shows higher methane yields during anaerobic fermentation.

  2. Microwave assisted wet oxidation of p-nitrophenol

    Institute of Scientific and Technical Information of China (English)

    BO; Longli; CHEN; Shuo; QUAN; Xie; LIU; Xitao; ZHAO; Huimin

    2005-01-01

    Aqueous solution of p-nitrophenol (PNP) was treated continuously by microwave assisted wet oxidation while flowing through a granular activated carbon (GAC) fixed bed. PNP was pre-adsorbed onto GAC prior to being put into the reactor so as to prevent PNP adsorption on GAC during microwave irradiation. PNP solutions with different initial concentration (218.6 mg/L and 1200 mg/L) were treated under conditions of microwave power 500 W, liquid flow 6.4 mL/min and air flow 40 mL/min or 60 mL/min. The results indicated that the removal of PNP was higher than 90% and more than 65% PNP was mineralized. Phenol, nitrobenzene, hydroquinone and benzoquinone occurred as course products during the operation process, which were degraded further. The biodegradability of the outflow was improved greatly by microwave assisted wet oxidation.

  3. Evaluation of wet oxidation pretreatment for enzymatic hydrolysis of softwood

    DEFF Research Database (Denmark)

    Palonen, H.; Thomsen, A.B.; Tenkanen, M.;

    2004-01-01

    The wet oxidation pretreatment (water, oxygen, elevated temperature, and pressure) of softwood (Picea abies) was investigated for enhancing enzymatic hydrolysis. The pretreatment was preliminarily optimized. Six different combinations of reaction time, temperature, and pH were applied, and the...... compositions of solid and liquid fractions were analyzed. The solid fraction after wet oxidation contained 58-64% cellulose, 2-16% hemicellulose, and 24-30% lignin. The pretreatment series gave information about the roles of lignin and hemicellulose in the enzymatic hydrolysis. The temperature of the...... pretreatment, the residual hemicellulose content of the substrate, and the type of the commercial cellulase preparation used were the most important factors affecting the enzymatic hydrolysis. The highest sugar yield in a 72-h hydrolysis, 79% of theoretical, was obtained using a pretreatment of 200degreesC for...

  4. Catalytic partial oxidation of methane over porous silica supported VO{sub x} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pirovano, C.; Schoenborn, E.; Kalevaru, V.N.; Wohlrab, S.; Luecke, B.; Martin, A. [University Rostock e.V., Rostock (Germany). Leibniz Inst. for Catalysis

    2011-07-01

    High surface area mesoporous siliceous MCM-41 and SBA-15 materials have been used as supports to disperse vanadium oxide species using wet impregnation and incipient wetness impregnation methods. These materials were used as catalysts for the partial oxidation of methane (POM) to formaldehyde. The physico-chemical properties of the solids were studied by means of BET, DR-UV/Vis spectroscopy, Py-FTIR and TEM. The influence of support and the preparation method on the dispersion of VOx is also investigated. The catalytic properties of the catalysts were examined in a fixed bed stainless steel reactor at 923 K. So far a maximum production of formaldehyde can be detected on SBA-15 supported VOx-catalysts prepared by incipient wetness impregnation. On this V/SBA-15 material a covalent attachment of catalytic active molecular vanadium species dominates, which in turn leads to a lower activation temperature and thereby reduced over-oxidation. From the best case, the space time yield of HCHO could be reached close to 775 g{sub HCHO} Kg{sub cat}{sup -1} h{sup -1}. (orig.)

  5. Combined wet oxidation and alkaline hydrolysis of polyvinylchloride

    DEFF Research Database (Denmark)

    Sørensen, E.; Bjerre, A.B.

    1992-01-01

    In view of the widespread aversion to burning polyvinylchloride (PVC) together with municipal waste, we have attempted an alternative approach to its decomposition. This paper describes a combined wet oxidation/alkaline hydrolysis yielding water soluble, biodegradable products. Experiments were...... carried out at temperatures from 180-260 degree C and reaction times of 8-24 min. The chloride liberated provides information on the rate constants. Considering the measured Cl- and Chemical Oxygen Demand (COD) values, we find hydrolysis and oxidation processes to be interdependent. The main products are...

  6. Development of wet-proofed catalyst and catalytic exchange process for tritium extraction

    Energy Technology Data Exchange (ETDEWEB)

    Song, Myung Jae; Son, Soon Hwan; Chung, Yang Gun; Lee, Gab Bock [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center

    1995-12-31

    To apply a liquid phase catalytic exchange(LPCE) process for the tritium extraction from tritiated heavy water, the wet proofed catalyst to allow the hydrogen isotopic exchange reaction between liquid water and hydrogen gas was developed. A styrene divinyl benzene copolymer was selected as am effective catalyst support and prepared by suspension copolymerization. After post-treatment, final catalyst supports were dipped in chloroplatinic acid solution. The catalyst support had a good physical properties at a particular preparation condition. The catalytic performance was successfully verified through hydrogen isotopic exchange reaction in the exchange column. A mathematical model for the tritium removal process consisted of LPCE front-ended process and cryogenic distillation process was established using the NTU-HTU method for LPCE column and the FUG method for cryogenic distillation column, respectively. A computer program was developed using the model and then used to investigate optimum design variables which affect the size of columns and tritium inventory (author). 84 refs., 113 figs.

  7. Wet-oxidation waste management system for CELSS

    Science.gov (United States)

    Takahashi, Y.; Ohya, H.

    1986-01-01

    A wet oxidation system will be useful in the Closed Ecological Life Support System (CELSS) as a facility to treat organic wastes and to redistribute inorganic compounds and elements. However at rather higher temperatures needed in this reaction, for instance, at 260 deg C, only 80% of organic in a raw material can be oxidized, and 20% of it will remain in the liquid mainly as acetic acid, which is virtually noncombustible. Furthermore, nitrogen is transformed to ammonium ions which normally cannot be absorbed by plants. To resolve these problems, it becomes necessary to use catalysts. Noble metals such as Ru, Rh and so on have proved to be partially effective as these catalysts. That is, oxidation does not occur completely, and the unexpected denitrification, instead of the expected nitrification, occurs. So, it is essential to develop the catalysts which are able to realize the complete oxidation and the nitrification.

  8. Spacecraft Water Regeneration by Catalytic Wet Air Oxidation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this project is to develop advanced catalysts for a volatile removal assembly used to purify spacecraft water. The innovation of the proposed...

  9. Catalytic wet air oxidation of organic pollutants in waste waters

    OpenAIRE

    Gomes, Helder; Figueiredo, José; Boaventura, Rui; Faria, Joaquim

    2001-01-01

    Organic compounds are involved iii the manufacture of a wide variety of chemical products, generating in the process different kinds of liquid effluents with high chemical oxygen demand (COD) and high toxicity. Discharge of these waters without treatment into a river course is unacceptable, due to the toxic potential of some organic compounds or to depletion of the dissolved oxygen level, which can decrease below the level considered necessary to support aquatic life.

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

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

  11. Catalytic abatement of nitrous oxide from nitric and production

    NARCIS (Netherlands)

    Oonk, J.

    1998-01-01

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

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    OpenAIRE

    Yan Gong; Lu Lin; Zhipei Yan

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Yan Gong

    2011-02-01

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

  15. Wet oxidation pretreatment of rape straw for ethanol production

    International Nuclear Information System (INIS)

    Rape straw can be used for production of second generation bioethanol. In this paper we optimized the pretreatment of rape straw for this purpose using Wet oxidation (WO). The effect of reaction temperature, reaction time, and oxygen gas pressure was investigated for maximum ethanol yield via Simultaneous Saccharification and Fermentation (SSF). To reduce the water use and increase the energy efficiency in WO pretreatment features like recycling liquid (filtrate), presoaking of rape straw in water or recycled filtrate before WO, skip washing pretreated solids (filter cake) after WO, or use of whole slurry (Filter cake + filtrate) in SSF were also tested. Except ethanol yields, pretreatment methods were evaluated based on achieved glucose yields, amount of water used, recovery of cellulose, hemicellulose, and lignin. The highest ethanol yield obtained was 67% after fermenting the whole slurry produced by WO at 205 °C for 3 min with 12 bar of oxygen gas pressure and featured with presoaking in water. At these conditions after pre-treatment, cellulose and hemicellulose was recovered quantitatively (100%) together with 86% of the lignin. WO treatments of 2–3 min at 205–210 °C with 12 bar of oxygen gas produced higher ethanol yields and cellulose, hemicelluloses, and lignin recoveries, than 15 min WO treatment at 195 °C. Also, recycling filtrate and use of higher oxygen gas pressure reduced recovery of materials. The use of filtrate could be inhibitory for the yeast, but also reduced lactic acid formation in SSF. -- Highlights: ► Wet Oxidation pretreatment on rape straw for sugar and ethanol production. ► Variables were reaction time, temperature, and oxygen gas pressure. ► Also, other configurations for increase of water and energy efficiency. ► Short Wet oxidation pretreatment (2–3 min) produced highest ethanol yield. ► After these pretreatment conditions recovery of lignin in solids was 86%.

  16. Low-temperature catalytic gasification of wet industrial wastes. FY 1991--1992 interim report

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D.C.; Neuenschwander, G.G.; Hart, T.R.; Phelps, M.R.; Sealock, L.J. Jr.

    1993-07-01

    A catalytic gasification system operating in a pressurized water environment has been developed and refined at Pacific Northwest Laboratory (PNL) for over 12 years. Initial experiments were aimed at developing kinetics information for steam gasification of biomass in the presence of catalysts. The combined use of alkali and metal catalysts was reported for gasification of biomass and its components at low temperatures (350{degrees}C to 450{degrees}C). From the fundamental research evolved the concept of a pressurized, catalytic gasification system for converting wet biomass feedstocks to fuel gas. Extensive batch reactor testing and limited continuous reactor system (CRS) testing were undertaken in the development of this system under sponsorship of the US Department of Energy. A wide range of biomass feedstocks were tested, and the importance of the nickel metal catalyst was identified. Specific use of this process for treating food processing wastes was also studied. The concept application was further expanded to encompass cleanup of hazardous wastewater streams, and results were reported for batch reactor tests and continuous reactor tests. Ongoing work at PNL focuses on refining the catalyst and scaling the system to long-term industrial needs. The process is licensed as the Thermochemical Environmental Energy System (TEES{reg_sign}) to Onsite*Ofsite, Inc., of Duarte, California. This report is a follow-on to the 1989--90 interim report [Elliott et al. 1991], which reviewed the results of the studies conducted with a fixed-bed, continuous-feed, tubular reactor. The discussion here provides an overview of experiments on the wide range of potential feedstock materials conducted in a batch reactor; development of new catalyst materials; and tests performed in continuous-flow reactors at three scales. The appendices contain the history and background of the process development, as well as more detailed descriptions and results of the recent studies.

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

    Institute of Scientific and Technical Information of China (English)

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

    2003-01-01

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

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

    International Nuclear Information System (INIS)

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

  19. Green chemicals from pulp production black liquor by partial wet oxidation.

    Science.gov (United States)

    Muddassar, Hassan Raja; Melin, Kristian; de Villalba Kokkonen, Daniela; Riera, Gerard Viader; Golam, Sarwar; Koskinen, Jukka

    2015-11-01

    To reduce greenhouse gas emissions, more sustainable sources of energy, fuel and chemicals are needed. Biomass side streams such as black liquor, which is a by-product of pulp production, has the potential to be used for this purpose. The aim of the study was the production of carboxylic acids, such as lactic acid, formic acid and acetic acid, from kraft and non-wood black liquor. The processes studied were partial wet oxidation (PWO) and catalytic partial wet oxidation (CPWO). The results show that the yield of carboxylic acid is higher when treated by PWO than the results from CPWO at temperatures of 170 °C and 230 °C. The results shows that the PWO process can increase the yield of carboxylic acids and hydroxy acids in black liquor, reduce lignin content and decrease pH, which makes further separation of the acids more favourable. The hydroxy acids are valuable raw materials for biopolymers, and acetic acid and formic acid are commonly used chemicals conventionally produced from fossil feedstock. PMID:26377325

  20. Kinetics of Wet Air Oxidation of Wastewater from Natural Fiber Web Desizing

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This work described the application of wet air oxidation (WAO) to the treatment of desizing wastewater from natural fiber processing. A two-liter autoclave batch reactor was used for the experiments. The range of operating temperature examined was between 150 and 290℃, and partial pressure of oxygen ranged from 0.375 to 2.25 MPa standardized at 25℃. Variations in Chemical Oxygen Demand(COD) and Total Organic Carbon(TOC) were monitored during each experiment and used to assess the performance of the process. Experimental results showed that WAO can be an efficient method for the treatment of desizing wnstewater. Furthermore, Catalytic Wet Air Oxidation (CWAO) was applied to reduce the reaction temperature and pressure in WAO process. A higher COD removal ratio was achieved under more mild reaction condition with the aid of CWAO. A mathematical model was also proposed to simulate the WAO process of desizing wastewater, in which three distinct kinetics steps were considered to describe the degradation of starch. The model simulations were in well agreement with the experimental data.

  1. Surface and catalytic properties of doped tin oxide nanoparticles

    Science.gov (United States)

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

    2010-10-01

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

  2. Visualizing the mobility of silver during catalytic soot oxidation

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  3. Leachate Treatment UsingWet Air Oxidation Processes

    Directory of Open Access Journals (Sweden)

    A Ebrahimi

    2011-04-01

    Full Text Available "nBackground and Objectives: Wet air oxidation (WAO is One of the advanced oxidation process which reduce organic matter concentration from industrial wastewater, toxic and non biodegradable substances and, solid waste leachate,etc. In this study the efficiency of wet air oxidation method in leachate treatment generating from Esfahan Composting factory was Evaluated."nMaterial and Methods: The experiment was carried out by adding 1.5 Lit of pretreated leachate sample the steel reactor with the volume of 3L. The reactor then underwent10 bar pressure at different temperature (100, 200 and 300 °C and various retention time (30, 60 and 90 min. Leachate sample in 18 stages from composting factory in Isfahan in the volume of 20 Lit was taken and the WAO method, was used for pre-treatments. Removal efficiency of COD, BOD, NH4-N, NO3 and TSS were examined."nResults: The results showed that the removal efficiency was more than 35% for COD, 38% for BOD, and 85% for TSS within one hour of reaction. The Maximum removal efficiency obtained in this study were 53.3% for NH4-N and 73.9 % forNO3-N."nConclusion: the results indicate that the reaction temperatures are the most important factors affecting degradation of organic matter. COD and BOD5 removal efficiency by WAO process increased as the time of reaction went up. In addition, BOD5/COD ratios of the effluents, which are generally regarded as an important index of biodegradability of leachate sample, were determined and improved grately as it reached to 84%. TheWAO process presented in this paper is considered an efficient process for pretreatment of leachate, as the COD, BOD5 and NO3 reduction observed in leachate samples.

  4. Catalytic oxidation of pulping effluent by activated carbon-supported heterogeneous catalysts.

    Science.gov (United States)

    Yadav, Bholu Ram; Garg, Anurag

    2016-01-01

    The present study deals with the non-catalytic and catalytic wet oxidation (CWO) for the removal of persistent organic compounds from the pulping effluent. Two activated carbon-supported heterogeneous catalysts (Cu/Ce/AC and Cu/Mn/AC) were used for CWO after characterization by the following techniques: temperature-programmed reduction, Fourier transform infrared spectroscopy and thermo-gravimetric analysis. The oxidation reaction was performed in a batch high-pressure reactor (capacity = 0.7  L) at moderate oxidation conditions (temperature = 190°C and oxygen pressure = 0.9 MPa). With Cu/Ce/AC catalyst, the maximum chemical oxygen demand (COD), total organic carbon (TOC) and lignin removals of 79%, 77% and 88% were achieved compared to only 50% removal during the non-catalytic process. The 5-day biochemical oxygen demand (BOD5) to COD ratio (a measure for biodegradability) of the pulping effluent was improved to 0.52 from an initial value of 0.16. The mass balance calculations for solid recovered after CWO reaction showed 8% and 10% deduction in catalyst mass primarily attributed to the loss of carbon and metal leaching. After the CWO process, carbon deposition was also observed on the recovered catalyst which was responsible for around 3-4% TOC reduction. PMID:26508075

  5. Catalytic Partial Oxidation of Biomass/Oil Mixture

    Czech Academy of Sciences Publication Activity Database

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

    2013-01-01

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

  6. Trends in the Catalytic CO Oxidation Activity of Nanoparticles

    DEFF Research Database (Denmark)

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

    2008-01-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

    2014-01-01

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

  8. Comparison between wet oxidation and steam explosion as pretreatment methods for enzymatic hydrolysis of sugarcane bagasse

    DEFF Research Database (Denmark)

    Medina, Carlos Martín; Marcet, M.; Thomsen, Anne Belinda

    2008-01-01

    Alkaline wet oxidation and steam explosion pretreatments of sugarcane bagasse were compared with regard to biomass fractionation, formation of by-products, and enzymatic convertibility of the pretreated material. Wet oxidation led to the solubilisation of 82% of xylan and 50% of lignin, and to a...... significantly in steam explosion. This investigation demonstrates the potential of wet oxidation as a promising pretreatment method for enzyme-based bagasse-to-ethanol processes....

  9. The effect of noble metals on catalytic methanation reaction over supported Mn/Ni oxide based catalysts

    OpenAIRE

    Wan Azelee Wan Abu Bakar; Rusmidah Ali; Nurul Shafeeqa Mohammad

    2015-01-01

    Carbon dioxide (CO2) in sour natural gas can be removed using green technology via catalytic methanation reaction by converting CO2 to methane (CH4) gas. Using waste to wealth concept, production of CH4 would increase as well as creating environmental friendly approach for the purification of natural gas. In this research, a series of alumina supported manganese–nickel oxide based catalysts doped with noble metals such as ruthenium and palladium were prepared by wetness impregnation method. T...

  10. Lignin Valorization using Heterogenous Catalytic Oxidation

    DEFF Research Database (Denmark)

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

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

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

    Institute of Scientific and Technical Information of China (English)

    过玮; 刘利民; 林洪; 宋俊峰

    2002-01-01

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

  12. Catalytic combustion over high temperature stable metal oxides

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  13. Transformation and removal of wood extractives from pulp mill sludge using wet oxidation and thermal hydrolysis.

    Science.gov (United States)

    Baroutian, Saeid; Robinson, Murray; Smit, Anne-Marie; Wijeyekoon, Suren; Gapes, Daniel

    2013-10-01

    In order to remove wood extractive compounds from pulp mill sludge and thereby enhancing anaerobic digestibility, samples were subjected to either oxidative hydrothermal treatment (wet oxidation) or non-oxidative hydrothermal treatment (thermal hydrolysis). Treatments were carried out at 220 °C with initial pressure of 20 bar. More than 90% destruction of extractive compounds was observed after 20 min of wet oxidation. Wet oxidation eliminated 95.7% of phenolics, 98.6% fatty acids, 99.8% resin acids and 100% of phytosterols in 120 min. Acetic acid concentration increased by approximately 2 g/l after 120 min of wet oxidation. This has potential for rendering sludge more amenable to anaerobic digestion. In contrast thermal hydrolysis was found to be ineffective in degrading extractive compounds. Wet oxidation is considered to be an effective process for removal of recalcitrant and inhibitive compounds through hydrothermal pre-treatment of pulp mill sludge. PMID:23948266

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  15. Wet oxidation pretreatment of rape straw for ethanol production

    DEFF Research Database (Denmark)

    Arvaniti, Efthalia; Bjerre, Anne Belinda; Schmidt, Jens Ejbye

    2012-01-01

    Rape straw can be used for production of second generation bioethanol. In this paper we optimized the pretreatment of rape straw for this purpose using Wet oxidation (WO). The effect of reaction temperature, reaction time, and oxygen gas pressure was investigated for maximum ethanol yield via...... slurry (Filter cake + filtrate) in SSF were also tested. Except ethanol yields, pretreatment methods were evaluated based on achieved glucose yields, amount of water used, recovery of cellulose, hemicellulose, and lignin.The highest ethanol yield obtained was 67% after fermenting the whole slurry...... gas produced higher ethanol yields and cellulose, hemicelluloses, and lignin recoveries, than 15 min WO treatment at 195 °C. Also, recycling filtrate and use of higher oxygen gas pressure reduced recovery of materials. The use of filtrate could be inhibitory for the yeast, but also reduced lactic acid...

  16. Removal of ammonia from aqueous solutions by catalytic oxidation with copper-based rare earth composite metal materials: catalytic performance, characterization, and cytotoxicity evaluation

    Institute of Scientific and Technical Information of China (English)

    Chang-Mao Hung

    2011-01-01

    Ammonia (NH3) has an important use in the chemical industry and is widely found in industrial wastewater.For this investigation of copper-based rare earth composite metal materials,aqueous solutions containing 400 mg/L of ammonia were oxidized in a batch-bed reactor with a catalyst prepared by the co-precipitation of copper nitrate,lanthanum nitrate and cerium nitrate.Barely any of the dissolved ammonia was removed by wet oxidation without a catalyst,but about 88% of the ammonia was reduced during wet oxidation over the catalysts at 423 K with an oxygen partial pressure of 4.0 MPa.The catalytic redox behavior was determined by cyclic voltammetry (CV).Furthermore,the catalysts were characterized using thermogravimetric analyzer (TGA) and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX),which showed that the catalytic behavior was related to the metal oxide properties of the catalyst.In addition,the copper-lanthanum-cerium composite-induced cytotoxicity in the human lung MRC-5 cell line was tested,and the percentage cell survival was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetra-zolium (MTS) analysis in vitro.No apparent cytotoxicity was observed when the human lung cells were exposed to the copper-lanthanum-cerium composite.

  17. Catalytic Conversion of Methanol by Oxidative Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

  18. Preliminary comparison of three processes of AlN oxidation: dry, wet and mixed ones

    Directory of Open Access Journals (Sweden)

    Korbutowicz R.

    2016-03-01

    Full Text Available Three methods of AlN layers oxidation: dry, wet and mixed (wet with oxygen were compared. Some physical parameters of oxidized thin films of aluminum nitride (AlN layers grown on silicon Si(1 1 1 were investigated by means Energy-Dispersive X-ray Spectroscopy (EDS and Spectroscopic Ellipsometry (SE. Three series of the thermal oxidations processes were carried out at 1012 °C in pure nitrogen as carrying gas and various gas ambients: (a dry oxidation with oxygen, (b wet oxidation with water steam and (c mixed atmosphere with various process times. All the research methods have shown that along with the rising of the oxidation time, AlN layer across the aluminum oxide nitride transforms to aluminum oxide. The mixed oxidation was a faster method than the dry or wet ones.

  19. Selective catalytic oxidations of alkylaromatic compounds

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

  20. Structure and catalytic reactivity of Rh oxides

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  1. Role of Bismuth Oxide in Bi-MCo2O4(M=Co,Ni,Cu,Zn) Catalysts for Wet Air Oxidation of Acetic Acid

    Institute of Scientific and Technical Information of China (English)

    JIANG Peng-bo; CHENG Tie-xin; ZHUANG Hong; CUI Xiang-hao; BI Ying-li; ZHEN Kai-ji

    2004-01-01

    Two series of cobalt(Ⅲ)-containing spinel catalysts were prepared by the decomposition of the corresponding nitrates. The catalysts doped with bismuth oxide exhibit a higher activity in the wet air oxidation of acetic acid than those without dopant bismuth oxide. The catalysts were investigated by XRD, TEM, ESR, UV-DRS and XPS, and the interaction between Co and Bi was studied as well. It has been found that nano-sized bismuth oxide is paved on the surface of cobalt spinel crystal and the structures of cobalt(Ⅲ)-containing spinel are still maintained. The shift of the binding energy of Bi4f7/2 is related to the catalytic activity of these catalysts doped with bismuth oxide.

  2. Manganese zinc ferrite nanoparticles as efficient catalysts for wet peroxide oxidation of organic aqueous wastes

    Indian Academy of Sciences (India)

    Manju Kurian; Divya S Nair

    2015-03-01

    Manganese substituted zinc nanoparticles, MnxZn1−xFe2O4 (x = 0.0, 0.25, 0.5, 0.75, 1.0) prepared by sol gel method were found to be efficient catalysts for wet peroxide oxidation of 4-chlorophenol. Complete degradation of the target pollutant occurred within 90 min at 70°C. Zinc substitution enhanced the catalytic efficiency and the unsubstituted ZnFe2O4 oxidized the target compound completely within 45 min. Studies on the effect of reaction variables revealed that only a small amount of the oxidant, H2O2 (3–4 mL) is required for complete degradation of 4-chlorophenol. More than 80% of 4-chlorophenol was removed at catalyst concentrations of 100 mg/L. Direct correlation between the amount of catalyst present and the extent of degradation of 4-chlorophenol was observed, ruling out hesterogeneous-homogeneous mechanism. The catalysts are reusable and complete degradation of target pollutant occurred after five successive runs. The extent of iron leaching was fairly low after five consecutive cycles indicating the mechanism to be heterogeneous.

  3. Catalytic oxidation of albendazole using molybdenum supported on carbon nanotubes as catalyst

    International Nuclear Information System (INIS)

    The catalytic oxidation reaction of the thioether group (-S-) in the structure to the drug albendazole (C12H15N3O2S) was studied in order to obtain a pharmacologically active molecule known as albendazole sulfoxide. With this purpose, three heterogeneous catalysts were prepared using molybdenum (Mo) as active phase and carbon nanotubes as a multiple-layer catalyst support. The incorporation of the active phase was performed by wet impregnation, with subsequent calcination for 4 hours at 400 oC. For the catalytic oxidation reaction was employed hydrogen peroxide-urea (H2NCONH2·H2O2) as oxidizing agent and methanol (CH3OH) as reaction medium. The textural and morphology characterization of carbon nanoparticles and catalysts was carried out by adsorption-desorption of N2 (BET) and scanning electron microscopy (SEM). The identification and quantification of the reaction products were followed by Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC), respectively. With the yield, selectivity and conversion higher than 90% after 60 minutes of reaction, albendazole sulphoxide was obtained as major product of oxidation reaction. (author)

  4. Preliminary comparison of three processes of AlN oxidation: dry, wet and mixed ones

    OpenAIRE

    Korbutowicz R.; Zakrzewski A.

    2016-01-01

    Three methods of AlN layers oxidation: dry, wet and mixed (wet with oxygen) were compared. Some physical parameters of oxidized thin films of aluminum nitride (AlN) layers grown on silicon Si(1 1 1) were investigated by means Energy-Dispersive X-ray Spectroscopy (EDS) and Spectroscopic Ellipsometry (SE). Three series of the thermal oxidations processes were carried out at 1012 °C in pure nitrogen as carrying gas and various gas ambients: (a) dry oxidation with oxygen, (b) wet oxidation with w...

  5. Treatment of hydraulic fracturing wastewater by wet air oxidation.

    Science.gov (United States)

    Wang, Wei; Yan, Xiuyi; Zhou, Jinghui; Ma, Jiuli

    2016-01-01

    Wastewater produced by hydraulic fracturing for oil and gas production is characterized by high salinity and high chemical oxygen demand (COD). We applied a combination of flocculation and wet air oxidation technology to optimize the reduction of COD in the treatment of hydraulic fracturing wastewater. The experiments used different values of flocculant, coagulant, and oxidizing agent added to the wastewater, as well as different reaction times and treatment temperatures. The use of flocculants for the pretreatment of fracturing wastewater was shown to improve treatment efficiency. The addition of 500 mg/L of polyaluminum chloride (PAC) and 20 mg/L of anionic polyacrylamide (APAM) during pretreatment resulted in a COD removal ratio of 8.2% and reduced the suspended solid concentration of fracturing wastewater to 150 mg/L. For a solution of pretreated fracturing wastewater with 12 mL of added H2O2, the COD was reduced to 104 mg/L when reacted at 300 °C for 75 min, and reduced to 127 mg/L when reacted at the same temperature for 45 min while using a 1 L autoclave. An optimal combination of these parameters produced treated wastewater that met the GB 8978-1996 'Integrated Wastewater Discharge Standard' level I emission standard. PMID:26942530

  6. Catalytic oxidation of CO on Ir(100)

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-15

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

  7. Catalytic Partial Oxidation of Biomass/Oil Dispersion

    Czech Academy of Sciences Publication Activity Database

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

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

  8. Catalytic Partial Oxidation of Biomass/Oil Mixture

    OpenAIRE

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

    2013-01-01

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

  9. Deep desulfurization of diesel fuels by catalytic oxidation

    Institute of Scientific and Technical Information of China (English)

    YU Guoxian; CHEN Hui; LU Shanxiang; ZHU Zhongnan

    2007-01-01

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

  10. Development studies of a novel wet oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, T.W.; Dooge, P.M.

    1996-12-31

    The objective of this study is to develop a novel catalytic chemical oxidation process that can be used to effectively treat multi-component wastes with a minimum of pretreatment characterization, thus providing a versatile, non-combustion method which will destroy hazardous organic compounds while simultaneously containing and concentrating toxic and radioactive metals for recovery or disposal in a readily stabilized matrix. Although the DETOX{sup SM} process had been tested to a limited extent for potential application to mixed wastes, there had not been sufficient experience with the process to determine its range of application to multicomponent waste forms. The potential applications of the process needed to be better identified. Then, the process needed to be demonstrated on wastes and remediate types on a practical scale in order that data could be obtained on application range, equipment size, capital and operating costs, effectiveness, safety, reliability, permittability, and potential commercial applications of the process. The approach for the project was, therefore, to identify the potential range of applications of the process (Phase I), to choose demonstration sites and design a demonstration prototype (Phase II), to fabricate and shakedown the demonstration unit (Phase III), then finally to demonstrate the process on surrogate hazardous and mixed wastes, and on actual mixed wastes (Phase IV).

  11. Photo-catalytic activity of Zn1-x Mn x S nanocrystals synthesized by wet chemical technique

    Directory of Open Access Journals (Sweden)

    Singh Karamjit

    2011-01-01

    Full Text Available Abstract Polyvinyl pyrrolidone capped Zn1-x Mn x S (0 ≤ x ≤ 0.1 nanocrystals have been synthesized using wet chemical co-precipitation method. Crystallographic and morphological characterization of the synthesized materials have been done using X-ray diffraction and transmission electron microscope. Crystallographic studies show the zinc blende crystals having average crystallite size approx. 3 nm, which is almost similar to the average particle size calculated from electron micrographs. Atomic absorption spectrometer has been used for qualitative and quantitative analysis of synthesized nanomaterials. Photo-catalytic activity has been studied using methylene blue dye as a test contaminant. Energy resolved luminescence spectra have been recorded for the detailed description of radiative and non-radiative recombination mechanisms. Photo-catalytic activity dependence on dopant concentration and luminescence quantum yield has been studied in detail.

  12. Development studies for a novel wet oxidation process. Phase 2

    International Nuclear Information System (INIS)

    DETOXSM is a catalyzed wet oxidation process which destroys organic materials in an acidic water solution of iron at 373 to 473 K. The solution can be used repeatedly to destroy great amounts of organic materials. Since the process is conducted in a contained vessel, air emissions from the process can be well controlled. The solution is also capable of dissolving and concentrating many heavy and radioactive metals for eventual stabilization and disposal. The Phase 2 effort for this project is site selection and engineering design for a DETOX demonstration unit. Site selection was made using a set of site selection criteria and evaluation factors. A survey of mixed wastes at DOE sites was conducted using the Interim Mixed Waste Inventory Report. Sites with likely suitable waste types were identified. Potential demonstration sites were ranked based on waste types, interest, regulatory needs, scheduling, ability to provide support, and available facilities. Engineering design for the demonstration unit is in progress and is being performed by Jacobs Applied Technology. The engineering design proceeded through preliminary process flow diagrams (PFDs), calculation of mass and energy balances for representative waste types, process and instrumentation diagrams (P and IDs), preparation of component specifications, and a firm cost estimate for fabrication of the demonstration unit

  13. Solid State, Surface and Catalytic Studies of Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kung, H. H.

    2004-11-23

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

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

    Science.gov (United States)

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

    2016-09-01

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

  15. Catalytic oxidative desulfurization of liquid hydrocarbon fuels using air

    Science.gov (United States)

    Sundararaman, Ramanathan

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

  16. Catalytic oxidation of carbon monoxide over supported palladium nanoparticles

    Science.gov (United States)

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

    2016-01-01

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

  17. Wet Oxidation Pre-Treatment – the Way To Improve Economics of Energy Production From Manure?

    DEFF Research Database (Denmark)

    Uellendahl, Hinrich; Mladenovska, Zuzana; Langvad, Niels Bo;

    2006-01-01

    and Wheatley, 1993). The combination of high temperature and pressure, together with the addition of oxygen in the wet oxidation process, has shown a superior potential for increasing the hydrolysis of lignocellulosic biomass with subsequent ethanol fermentation. In the present study the wet oxidation...... process was tested as pretreatment for increasing the biogas yield of the fiber fraction of manure. The wet oxidation pretreatment in combination with solid liquid separation of manure by using either chemical precipitation or decanter centrifuge (Møller et al., 2004) could be a promising option for a...

  18. Catalytic aerobic oxidation of bio-renewable chemicals

    DEFF Research Database (Denmark)

    Gorbanev, Yury

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

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

    Institute of Scientific and Technical Information of China (English)

    王恩过; 陈诵英

    2002-01-01

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

  20. A novel advanced oxidation process——wet electrocatalytic oxidation for high concentrated organic wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    DAI QiZhou; ZHOU MingHua; LEI LeCheng; ZHANG Xing Wang

    2007-01-01

    A novel advanced oxidation process-wet electrocatalytic oxidation(WEO)was studied with p-nitrophenol as model pollutant and β-PbO2 electrode as the anode.Compared with the effect of the individual wet air oxidation(WAO)and electrochemical oxidation(EO),the effect of WEO showed synergistic effect on COD removal under the conditions of temperature 160℃,C=1000mg·L-1,PN2=0.50MPa,Po2=0.9 MPa,current density=3 mA·cm-2,Na2SO4 3 g·L-1.And the synergistic factor got the best value of 0.98 within 120 min after 180 min treatment.The synergistic factor was studied after 120 min treatment at 100℃,120℃,140℃and 160℃,and the effect of 120℃was the best with the value of 1.26.Possible mechanism for the synergistic effect was discussed based on the analysis of free-radical generation and intermediates detected by HPLC and GC/MS.

  1. The Study of LeachateTreatment by Using Three Advanced Oxidation Process Based Wet air Oxidation

    Directory of Open Access Journals (Sweden)

    Behroz Karimi

    2013-01-01

    Full Text Available Wet air oxidation is regarded as appropriate options for wastewater treatment with average organic compounds. The general purpose of this research is to determine the efficiency of three wet air oxidation methods, wet oxidation with hydrogen peroxide and absorption with activated carbon in removing organic matter and nitrogenous compounds from Isfahan's urban leachate. A leachate sample with the volume of 1.5 liters entered into a steel reactor with the volume of three liters and was put under a 10-bar pressure, at temperatures of 100, 200, and 300[degree sign] as well as three retention times of 30, 60, and 90 minutes. The sample was placed at 18 stages of leachate storage ponds in Isfahan Compost Plant with the volume of 20 liters, using three WPO, WAO methods and a combination of WAO/GAC for leachate pre-treatment. Thirty percent of pure oxygen and hydrogen peroxide were applied as oxidation agents. The COD removal efficiency in WAO method is 7.8-33.3%, in BOD is 14.7-50.6%, the maximum removal percentage (efficiency for NH4-N is 53.3% and for NO3-N is 56.4-73.9%. The removal efficiency of COD and BOD5 is 4.6%-34 and 24%-50 respectively in WPO method. Adding GAC to the reactor, the removal efficiency of all parameters was improved. The maximum removal efficiency was increased 48% for COD, 31%-43.6 for BOD5 by a combinational method, and the ratio of BOD5/COD was also increased to 90%. In this paper, WAO and WPO process was used for Leachate pre-treatment and WAO/GAC combinational process was applied for improving the organic matter removal and leachate treatment; it was also determined that the recent process is much more efficient in removing resistant organic matter.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

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

  3. Development of a novel wet oxidation process for hazardous and mixed wastes

    International Nuclear Information System (INIS)

    Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides. These materials are often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. The over all objective of the effort described here is to develop a novel catalytic wet oxidation process for the treatment of these multi-component wastes, with the aim of providing a versatile, non-thermal method which will destroy hazardous organic compounds while simultaneously containing and concentrating toxic and radioactive metals for recovery or disposal in a readily stabilized matrix. The DETOX process uses a unique combination of metal catalysts to increase the rate of oxidation of organic materials. The metal catalysts are in the form of salts dissolved in a dilute acid solution. A typical catalyst composition is 60% ferric chloride, 3--4% hydrochloric acid, 0.13% platinum ions, and 0.13% ruthenium ions in a water solution. The catalyst solution is maintained at 423--473 K. Wastes are introduced into contact with the solution, where their organic portion is oxidized to carbon dioxide and water. If the organic portion is chlorinated, hydrogen chloride will be produced as a product. The process is a viable alternative to incineration for the treatment of organic mixed wastes. Estimated costs for waste treatment using the process are from $2.50/kg to $25.00/kg, depending on the size of the unit and the amount of waste processed. Process units can be mobile for on-site treatment of wastes. Results from phase 1 and 2, design and engineering studies, are described

  4. Wet deposition of oxidized nitrogen in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of wet deposition of oxidized nitrogen in the Pacific Northwest...

  5. Thermal wet oxidation improves anaerobic biodegradability of raw and digested biowaste

    DEFF Research Database (Denmark)

    Lissens, G.; Thomsen, Anne Belinda; De Baere, L.;

    2004-01-01

    Anaerobic digestion of solid biowaste generally results in relatively low methane yields of 50-60% of the theoretical maximum. Increased methane recovery from organic waste would lead to reduced handling of digested solilds, lower methane emissions to the environment, and higher green energy....... Measured methane yields for raw yard waste, wet oxidized yard waste, raw food waste, and wet oxidized food waste were 345, 685, 536, and 571 mL of CH4/g of volatile suspended solids, respectively. Higher oxygen pressure during wet oxidation of digested biowaste considerably increased the total methane...... profits. The objective of this research was to enhance the anaerobic biodegradability and methane yields from different biowastes (food waste, yard waste, and digested biowaste already treated in a full-scale biogas plant (DRANCO, Belgium)) by assessing thermal wet oxidation. The biodegradability of the...

  6. Energetic optimization of wet air oxidation process using experimental design coupled with process simulation

    International Nuclear Information System (INIS)

    Wet air oxidation process (WAO) is used for wastewater treatment, especially when it contains high chemical oxygen demand. With non-catalytic processes, temperatures between 200 and 350 °C and pressures between 15 and 30 MPa are generally applied. A method, based on the coupling of simulations and experimental design, is used to compare and optimize two reactors (adiabatic and isotherm), their volume being equal and fixed. The interest of an experimental design approach is to plan simulation and to present results in immediate response surface. Four parameters have been selected; temperature, pressure, chemical oxygen demand, air ratio. After achieving the 25 simulations of the “numerical design”, mass and energy balances were analysed through two energetic values integrated as the design responses: exergetic efficiency and minimum heat required by the process for the functioning. The surface response methodology determines which are the most influencing parameters on design responses. It also shows that temperature of reaction and air ratio are the most influencing parameters. At least elements to calculate the cost of the plant, for both reactors are given. Both reactors allow to get complete degradation of pollutants, but strategy of investment and control are opposite.

  7. Development Studies for a Novel Wet Oxidation Process

    Energy Technology Data Exchange (ETDEWEB)

    Delphi Research

    1999-09-30

    DETOX is a catalyzed wet oxidation process that destroys organic materials in an acidic water solution of iron at 373 to 473 K. The solution can be used repeatedly to destroy great amounts of organic materials. Since the process is conducted in a contained vessel, air emissions from the process can be well controlled. The solution is also capable of dissolving and concentrating many heavy and radioactive metals for eventual stabilization and disposal. The Phase III effort for this project is fabrication, assembly, and installation of the DETOX demonstration unit, preparation of documentation and training to meet site requirements for operation, followed by system run-in and shakedown testing of the unit prior to demonstration testing. The Title III design was completed and the unit was fabricated according to standards set forth by OSHA, EPA, the American Petroleum Institute (i.e., chemical and petroleum industry standards), and the ASME B-313 Piping Code requirements as agreed to in preliminary design meetings with primary stakeholders. The unit was assembled in three modules and two trailers and then shipped to the TNX facility at the Savannah River Site in September and october of 1996. On-going site integration tasks were address while delays in installation arose due to funding sources and costs. In March of 1997, Delphi was authorized to proceed with the installation of the unit, making electrical and mechanical connections necessary to operate the unit. All installation tasks were completed in August of 1997. Results of an Operational Readiness Review conducted in August 1997 verified that Delphi's procedures and documentation met the necessary requirements to operate the unit at SRS. Completion of the final checklist of WSRC requirements was then addressed including the Owner's Independent Inspection Report, verifying all components of the unit met B-31.3 standards. Final hydraulic and pneumatic tests were completed in November to satisfy the B-31

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

    KAUST Repository

    Takanabe, Kazuhiro

    2012-01-01

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

  9. Catalytic oxidation of tritium in air at ambient temperature

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

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

  11. Comparison between wet oxidation and steam explosion as pretreatment methods for enzymatic hydrolysis of sugarcane bagasse

    DEFF Research Database (Denmark)

    Medina, Carlos Martín; Marcet, M.; Thomsen, Anne Belinda

    2008-01-01

    Alkaline wet oxidation and steam explosion pretreatments of sugarcane bagasse were compared with regard to biomass fractionation, formation of by-products, and enzymatic convertibility of the pretreated material. Wet oxidation led to the solubilisation of 82% of xylan and 50% of lignin, and to a...... fraction than steam explosion did. A better enzymatic convertibility of cellulose was achieved for the wet-oxidised material (57.4 %) than for the steam-exploded material (48.9 %). Cellulose convertibility was lower for the whole slurry than for the washed solids in both pretreatments, but more...

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

    International Nuclear Information System (INIS)

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

  13. Catalytic oxidation of dithiols by a semisynthetic enzyme

    Energy Technology Data Exchange (ETDEWEB)

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

    1986-06-11

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-09-29

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

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

    Science.gov (United States)

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-03-17

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

  16. Catalytic properties and biomedical applications of cerium oxide nanoparticles

    KAUST Repository

    Walkey, Carl D.

    2014-11-10

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

  17. Wet strength improvement of unbleached kraft pulp through laccase catalyzed oxidation.

    Science.gov (United States)

    Lund, M; Felby, C

    2001-06-01

    Previous investigations have shown that laccase catalyzed oxidation of lignin containing wood fibers can enhance the strength of medium density fiberboards. In the present work it was investigated if laccase treatment had any impact on the tensile strength of a high yield unbleached kraft pulp. Treatment with laccase alone had only a very little effect on the wet strength of the pulp, whereas addition of lignin rich extractives increased the wet strength after the enzyme treatment significantly. A mediated oxidation gave a similar improvement of the wet tensile strength although no lignin was added to the fiber suspension. Furthermore, it was found that a heat treatment combined with a mediated oxidation gave a higher improvement in wet tensile strength than could be accounted for by the individual treatments. No change in dry tensile strength from the laccase treatment was observed. It is suggested that the observed improvement in wet tensile strength is related to polymerization of lignin on fibers in the hand sheet and/or coupling of phenoxy radicals on lignin associated to adjacent fibers. For the different mediators studied, a correlation was found between oxygen consumption upon mediated oxidation and generation of wet strength in the pulp. PMID:11397456

  18. Measurement of the oxidation-extraction of uranium from wet-process phosphoric acid

    International Nuclear Information System (INIS)

    The present invention relates to processes for the recovery of uranium from wet-process phosphoric acid and more particularly to the oxidation-extraction steps in the DEPA-TOPO process for such recovery. A more efficient use of oxidant is obtained by monitoring the redox potential during the extraction step

  19. An approach to modeling of silicon oxidation in a wet ultra-diluted ambient

    NARCIS (Netherlands)

    Kovalgin, A.Y.; Hof, A.J.; Schmitz, J.

    2005-01-01

    In this work, we make steps towards developing a new wet-oxidation model of silicon based on electron-stimulated dissociation of H2O molecules. The need for a new model arises from the fact that existing physical models are inadequate to describe the thin-oxide regime. Two regimes of silicon oxidati

  20. Degradation of quinoline by wet oxidation - kinetic aspects and reaction mechanisms

    DEFF Research Database (Denmark)

    Thomsen, A.B.

    1998-01-01

    The high temperature, high pressure wet oxidation reaction of quinoline has been studied as a function of initial concentration, pH and temperature. At neutral to acidic pH, it is effective in the oxidation of quinoline at 240 degrees C and above, whereas under alkaline conditions the reaction is...... markedly slowed down. The results indicate that the reaction is an auto-catalysed, free radical chain reaction transforming 99% of quinoline to other substances. Of the quinoline. 30-50% was oxidised to CO2 and H2O depending on the initial concentration. Wet oxidation of deuterium-labelled quinoline was...

  1. The Oxidation of AlN in Dry and Wet Oxygen

    Science.gov (United States)

    Opila, Elizabeth; Humphrey, Donald; Jacobson, Nathan; Yoshio, Tetsuo; Oda, Kohei

    1998-01-01

    The oxidation kinetics of AlN containing 3.5 wt% Y2O3 were studied by thermogravimetric analysis in dry oxygen and 10% H2O/balance oxygen at temperatures between 1000 and 1200 C for times between 48 and 100 h. The oxidation kinetics for AlN in dry oxygen were parabolic and of approximately the same magnitude and temperature dependence as other alumina forming materials. In this case, diffusion of oxygen and/or aluminum through the alumina scale is the rate limiting mechanism. The oxidation kinetics for AlN in wet oxygen were nearly linear and much more rapid than rates observed in dry oxygen. Numerous micropores were observed in the alumina formed on AIN in wet oxygen. These pores provide a fast path for oxygen transport. The linear kinetics observed in this case suggest that the interface reaction rate of AlN with wet oxygen is the oxidation rate limiting step.

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

    Science.gov (United States)

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

    2015-01-01

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

  3. Mercury Oxidation via Catalytic Barrier Filters Phase II

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-09-30

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

  4. Low temperature catalytic decomposition and oxidation of MTBE

    International Nuclear Information System (INIS)

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

  5. COMPARISON BETWEEN WET OXIDATION AND STEAM EXPLOSION AS PRETREATMENT METHODS FOR ENZYMATIC HYDROLYSIS OF SUGARCANE BAGASSE

    Directory of Open Access Journals (Sweden)

    Carlos Martín

    2008-08-01

    Full Text Available Alkaline wet oxidation and steam explosion pretreatments of sugarcane bagasse were compared with regard to biomass fractionation, formation of by-products, and enzymatic convertibility of the pretreated material. Wet oxidation led to the solubilisation of 82% of xylan and 50% of lignin, and to a two-fold increase of cellulose content in the pretreated solids, while steam explosion solubilised only 60% of xylan and 35% of lignin and increased cellulose content in the solid material by one third. Wet oxidation formed more aliphatic acids and phenolics, and less furan aldehydes in the liquid fraction than steam explosion did. A better enzymatic convertibility of cellulose was achieved for the wet-oxidised material (57.4 % than for the steam-exploded material (48.9 %. Cellulose convertibility was lower for the whole slurry than for the washed solids in both pretreatments, but more significantly in steam explosion. This investigation demonstrates the potential of wet oxidation as a promising pretreatment method for enzyme-based bagasse-to-ethanol processes.

  6. Low-temperature catalytic gasification of wet industrial wastes. FY 1993--1994 interim report

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D.C.; Hart, T.R.; Neuenschwander, G.G.; Deverman, G.S.; Werpy, T.A.; Phelps, M.R.; Baker, E.G.; Sealock, L.J. Jr.

    1995-03-01

    Process development research is continuing on a low-temperature, catalytic gasification system that has been demonstrated to convert organics in water (dilute or concentrated) to useful and environmentally safe gases. The system, licensed under the trade name Thermochemical Environmental Energy System (TEESO), treats a wide variety of feedstocks ranging from hazardous organics in water to waste sludges from food processing. The current research program is focused on the use of continuous-feed, tubular reactors systems for testing catalysts and feedstocks in the process. A range of catalysts have been tested, including nickel and other base metals, as well as ruthenium and other precious metals. Results of extensive testing show that feedstocks, ranging from 2% para-cresol in water to potato waste and spent grain, can be processed to > 99% reduction of chemical oxygen demand (COD). The product fuel gas contains from 40% up to 75% methane, depending on the feedstock. The balance of the gas is mostly carbon dioxide with < 5% hydrogen and usually < 1% ethane and higher hydrocarbons. The byproduct water stream carries residual organics from 10 to 1,000 mg/l COD, depending on the feedstock. The level of development of TEES has progressed to the initial phases of industrial process demonstration. Testing of industrial waste streams is under way at both the bench scale and engineering scale of development.

  7. Improved wet peroxide oxidation strategies for the treatment of chlorophenols

    OpenAIRE

    Muñoz, Macarena; de Pedro, Zahara M.; Casas, José Antonio; Rodríguez, Juan José

    2013-01-01

    Different advanced oxidation strategies have been investigated for the treatment of chlorophenols in aqueous phase with the aim of improving the removal efficiency in terms of mineralization, remanent by-products and kinetics. Those strategies were homogeneous Fenton-like oxidation and CWPO with two different own-prepared FexOy/γ-Al2O3 catalysts. The intensification of the process by increasing the temperature has been also evaluated. CWPO of chlorophenols with those catalysts has proved to b...

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

    Czech Academy of Sciences Publication Activity Database

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

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

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

    Science.gov (United States)

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

    2013-06-01

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

  10. A novel oxidation-based wet etching method for AlGaN/GaN heterostructures

    Institute of Scientific and Technical Information of China (English)

    Cai Jinbao; Wang Jinyan; Liu Yang; Xu Zhe; Wang Maojun; Yu Min; Xie Bing

    2013-01-01

    A novel wet etching method for AlGaN/GaN heterojunction structures is proposed using thermal oxidation followed by wet etching in KOH solution.It is found that an AlGaN/GaN heterostructure after high temperature oxidation above 700 ℃ could be etched off in a homothermal (70 ℃) KOH solution while the KOH solution had no etching effects on the region of the A1GaN/GaN heterostructure protected by a SiO2 layer during the oxidation process.A groove structure with 150 nm step depth on an AlGaN/GaN heterostructure was formed after 8 h thermal oxidation at 900 ℃ followed by 30 min treatment in 70 ℃ KOH solution.As the oxidation time increases,the etching depth approaches saturation and the roughness of the etched surface becomes much better.The physical mechanism of this phenomenon is also discussed.

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

    Science.gov (United States)

    Yagodovskii, V. D.

    2015-11-01

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

  12. Pretreatment of Reed by Wet Oxidation and Subsequent Utilization of the Pretreated Fibers for Ethanol Production

    DEFF Research Database (Denmark)

    Szijarto, Nora; Kádár, Zsófia; Varga, Eniko;

    2009-01-01

    lignocelluloses usually do. In the present study, wet oxidation was investigated as the pretreatment method to enhance the enzymatic digestibility of reed cellulose to soluble sugars and thus improve the convertibility of reed to ethanol. The most effective treatment increased the digestibility of reed cellulose...... by cellulases more than three times compared to the untreated control. During this wet oxidation, 51.7% of the hemicellulose and 58.3% of the lignin were solubilized, whereas 87.1% of the cellulose remained in the solids. After enzymatic hydrolysis of pretreated fibers from the same treatment, the...

  13. Formation and degradation of valuable intermediate products during wet oxidation of municipal sludge.

    Science.gov (United States)

    Baroutian, Saeid; Gapes, Daniel J; Sarmah, Ajit K; Farid, Mohammed M; Young, Brent R

    2016-04-01

    The current study investigated the formation of organic acids and alcohols as major intermediate products of wet oxidation of municipal sludge. Municipal sludge was subjected to 60-min wet oxidation at temperatures ranging from 220 to 240°C, with 20bar oxygen partial pressure. Acetic acid was the main intermediate compound produced in this study, followed by propionic, n-butyric, iso-butyric and pentanoic acids and methanol. It was found that the process severity has a significant influence on the formation and degradation of these intermediate products. PMID:26832394

  14. Continuous production of bio-oil by catalytic liquefaction from wet distiller’s grain with solubles (WDGS) from bio-ethanol production

    International Nuclear Information System (INIS)

    Bio-refinery concepts are currently receiving much attention due to the drive toward flexible, highly efficient systems for utilization of biomass for food, feed, fuel and bio-chemicals. One way of achieving this is through appropriate process integration, in this particular case combining enzymatic bio-ethanol production with catalytic liquefaction of the wet distillers grains with soluble, a byproduct from the bio-ethanol process. The catalytic liquefaction process is carried out at sub-critical conditions (280–370 °C and 25 MPa) in the presence of a homogeneous alkaline and a heterogeneous Zirconia catalyst, a process known as the Catliq® process. In the current work, catalytic conversion of WDGS was performed in a continuous pilot plant with a maximum capacity of 30 dm3 h−1 of wet biomass. In the process, WDGS was converted to bio-oil, gases and water-soluble organic compounds. The oil obtained was characterized using several analysis methods, among them elementary analysis and GC–MS. The study shows that WDGS can be converted to bio oil with high yields. The results also indicate that through the combination of bio-ethanol production and catalytic liquefaction, it is possible to significantly increase the liquid product yield and scope, opening up for a wider end use applicability. -- Highlights: ► Hydrothermal liquefaction of wet biomass. ► Product phase analysis: oil, acqeous, gas and mineral phase. ► Energy and mass balance evaluation.

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2016-01-01

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

  17. Wet oxidation behaviors of polycrystalline Si1-xGex films

    International Nuclear Information System (INIS)

    We investigated the oxidation behaviors of poly Si1-xGex films with a 15% and 42% Ge content. The films were deposited using ultrahigh vacuum chemical vapor deposition on a 1000 Aa thick thermal SiO2 layer, and were oxidized using a conventional furnace in wet oxygen ambient at 700 and 800 deg. C. The physical and chemical properties of the oxide were analyzed by using Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy before and after the oxidation. We observed that the Ge content in the oxide layer and oxidation rate increased with the increase of Ge content in poly Si1-xGex films. We also observed that Ge content in the oxide layer decreased with the increase of oxidation temperature

  18. Fabrication and characterization of a novel zinc oxide thin film piezoelectric micocantilever with wet etching method

    OpenAIRE

    Bhatia, Deepak; Sharma, Himanshu; Nawaz, S.; Meena, R. S.; Tomy, C. V.; Palkar, V. R.

    2015-01-01

    In this work the fabrication and characterization of a novel zinc oxide thin film piezoelectric micocantilever with wet etching method have been reported for the first time ever. The piezoelectric zinc oxide (ZnO) thin film was deposited using dielectric (RF magnetron) sputtering method. The crystalline structures, surface roughness (morphology) and charge reversal of ZnO film are evaluated by X-ray Diffractometer (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM), re...

  19. VAPOR-PHASE CRACKING AND WET OXIDATION AS POTENTIAL POLLUTANT CONTROL TECHNIQUES FOR COAL GASIFICATION

    Science.gov (United States)

    The report gives results of an investigation of two techniques (hydrocracking of heavy organics in the raw gas prior to quency, and wet oxidation of the gasifier condensate) for pollutant control in coal gasification processes. Bench-scale experiments were used to determine rates...

  20. Design, fabrication and testing of a wet oxidation waste processing system. [for manned space flight

    Science.gov (United States)

    1975-01-01

    The wet oxidation of sewage sludge during space flight was studied for water and gas recovery, and the elimination of overboard venting. The components of the system are described. Slurry and oxygen supply modules were fabricated and tested. Recommendations for redesign of the equipment are included.

  1. Ethanol production from maize silage as lignocellulosic biomass in anaerobically digested and wet-oxidized manure

    DEFF Research Database (Denmark)

    Oleskowicz-Popiel, Piotr; Lisiecki, P.; Holm-Nielsen, J.B.;

    2008-01-01

    investigated using 2 1 bioreactors. Wet oxidation performed for 20 min at 121 degrees C was found as the most suitable pretreatment conditions for AD manure. High ammonia concentration and significant amount of macro- and micro-nutrients in the AD manure had a positive influence on the ethanol fermentation. No...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  4. Development studies of a novel wet oxidation process

    International Nuclear Information System (INIS)

    Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides. These materials are often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. Incineration and similar combustive processes do not appear to be viable options for treatment of these waste streams due to various considerations. There is a need for non-combustion processes with a wide application range to treat the large majority of these waste forms. The non-combustion process should also be safe, effective, cost-competitive, permit-able, and preferrably mobile. This paper describes the DETOX process of organic waste oxidation

  5. Pretreatment of wheat straw using combined wet oxidation and alkaline hydrolysis resulting in convertible cellulose and hemicellulose

    DEFF Research Database (Denmark)

    Bjerre, A.B.; Bjerring Olesen, A.; Fernqvist, T.;

    1996-01-01

    The wet oxidation process of wheat straw has been studied as a pretreatment method to attain our main goal: To break down cellulose to glucose enzymatic, and secondly, to dissolve hemicellulose (e.g., for fermentation) without producing microbial inhibitors. Wet oxidation combined with base addit...

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

    Science.gov (United States)

    Wang, Feng; Ueda, Wataru

    2009-03-01

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

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

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-Hua; GAO Geng-Yu

    2006-01-01

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

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

    OpenAIRE

    Sathaporn Chuepeng

    2012-01-01

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

  9. Characteristics of titania supported copper oxide catalysts for wet air oxidation of phenol

    International Nuclear Information System (INIS)

    Various techniques have been used to characterize the CuO x/TiO2 catalysts with different copper loading. Surface area, pore volume and pore size distribution of the prepared catalysts were estimated from nitrogen adsorption isotherm. Temperature programmed reduction (TPR), X-ray diffraction (XRD), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) experiments were performed to investigate the chemical state of the copper species. The chemical state of copper in the CuO x/TiO2 catalysts varied with copper loading (1-25 wt.%): highly dispersed Cu2+ cluster for 1 and 5 wt.%, and bulk CuO for 7-25 wt.%. The activity and mineralization selectivity of the CuO x/TiO2 catalysts increased with copper loading up to 20 wt.%, and remained almost constant for higher copper loading. The optimum copper loading was 20 wt.% for the wet air oxidation of phenol over the CuO x/TiO2 catalysts in this work. The stability of the CuO x/TiO2 catalysts with different copper loading was also studied with respect to carbonaceous deposits and copper leaching

  10. Wet Aerobic Oxidation of Lignin into Aromatic Aldehydes Catalysed by a Perovskite-type Oxide: LaFe1-xCuxO3 (x=0, 0.1, 0.2

    Directory of Open Access Journals (Sweden)

    Lu Lin

    2009-07-01

    Full Text Available The perovskite-type oxide catalyst LaFe1-xCuxO3 (x=0, 0.1, 0.2 was prepared by the sol–gel method, and tested as a catalyst in the wet aerobic oxidation (WAO of lignin into aromatic aldehydes. The lignin conversion and the yield of each aromatic aldehyde were significantly enhanced in the catalytic process, compared with the non-catalyzed process. Moreover, it was shown that the stability of activity and structure of LaFe1-xCuxO3 (x=0, 0.1, 0.2 remained nearly unchanged after a series of successive recyclings of the catalytic reactions, indicating it was an efficient and recyclable heterogeneous catalyst for the conversion of lignin into aromatic aldehydes in the WAO process.

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

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

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

    OpenAIRE

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

    2005-01-01

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

  13. Oxidation Kinetics of Chemically Vapor-Deposited Silicon Carbide in Wet Oxygen

    Science.gov (United States)

    Opila, Elizabeth J.

    1994-01-01

    The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen (P(sub H2O) = 0.1 atm) at temperatures between 1200 C and 1400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the Deal and Grove model for oxidation of silicon. It was found that in an environment containing even small amounts of impurities, such as high-purity Al2O3 reaction tubes containing 200 ppm Na, water vapor enhanced the transport of these impurities to the oxidation sample. Oxidation rates increased under these conditions presumably because of the formation of less protective sodium alumino-silicate scales.

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

    Science.gov (United States)

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

    2014-09-01

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

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

    International Nuclear Information System (INIS)

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

  16. Effect of Alloying Additions on the Oxidation of High Speed Steels under Dry and Wet Conditions

    Institute of Scientific and Technical Information of China (English)

    F.C. RIZZO; M.J.MONTEIRO; S.R.J.SAUNDERS

    2009-01-01

    An investigation has been carried out into the effects of chromium and vanadium content on the oxidation rate and on the adhesion of oxide scales grown on three different chemical compositions of high speed steels under dry and wet conditions. The oxidation tests were carried out in a thermobalance at 650 ℃ for up to 14.4 ks. The mass gain of the specimens increased with increasing contents of water vapour. Alloy composition had no effect on the oxidation rate in dry conditions. The "adhesion" of the oxide scale was determined using indentation with a Rockwell C diamond and the pull adhesion test to determine the interfacial toughness and the tensile strength of the oxide metal bond, respectively. Generally, the results of the investigation indicated that oxide adhesion was lowest for the specimens exposed to dry conditions, and that with increasing water vapour content, the scale was more adherent. Indentation test results showed that an increase in the Ⅴ concentration was deleterious to oxidc adhesion in both the dry and wet environments, whereas an increase in the Cr-content had little effect on adhesion.

  17. Phytoxicity study of the products of wet oxidation of a representative biomass (lettuce)

    Science.gov (United States)

    Onisko, B. L.; Wydeven, T.

    1983-01-01

    In an attempt to verify the results reported previously concerning the phytotoxicity of wet-oxidation (wet-ox) products, lettuce solids were suspended in water and then heated to 548 K for 3.6 ksec (1 hr) under 4.1x10 to the -7 Pa (400 psig at 294 K) oxygen pressure and 1.52x10 to the 8th (1500 psig at 548 K) total pressure. Such treatment resulted in oxidation of 80% of the initial organic carbon to carbon dioxide. Thirty-three percent of the remaining organic carbon was present in acetic acid. Organic nitrogen in the feed was decreased 90% by the wet-ox treatment. Ammonia and nitrogen gas were the main nitrogen products. Analysis of the liquid product of wet-ox indicated that most of the minerals essential for plant growth were present. However, when tested using a lettuce-root growth-rate assay, the solution was toxic. This toxicity was not due to excessive salt or ammonia or to an improper pH. Analysis of the wet-ox solution revealed the presence of silver and chromium, thus implicating reactor corrosion as the cause of the phytotoxicity. Both cation and anion exchange resins removed the silver and the toxicity of the liquid effluent, indicating silver as the toxic component. Uptake of both silver and chromium by lettuce roots correlated with diminished root growth. Toxicity of the solution from wet-ox was not observed when precautions were taken to minimize contact of the liquid in the reactor with the metal reactor components.

  18. Modifications of oxidized Zircaloy-4 surface in contact with radiolysed wet air

    Energy Technology Data Exchange (ETDEWEB)

    Guipponi, C. [Universite de Lyon, Institut de Physique Nucleaire de Lyon, Universite Claude Bernard Lyon 1, CNRS UMR5822, 4 rue Enrico Fermi, 69 622 Villeurbanne Cedex (France); Millard-Pinard, N., E-mail: millard@ipnl.in2p3.fr [Universite de Lyon, Institut de Physique Nucleaire de Lyon, Universite Claude Bernard Lyon 1, CNRS UMR5822, 4 rue Enrico Fermi, 69 622 Villeurbanne Cedex (France); Bererd, N. [Universite de Lyon, Institut de Physique Nucleaire de Lyon, Universite Claude Bernard Lyon 1, CNRS UMR5822, 4 rue Enrico Fermi, 69 622 Villeurbanne Cedex (France); Universite de Lyon, UCBL-IUT Lyon 1, departement chimie, 43 Bd du 11 novembre 1918, F-69622 Villeurbanne Cedex (France); Serris, E.; Pijolat, M.; Peres, V. [Ecole Nationale Superieure des Mines de Saint Etienne, Centre SPIN, CNRS UMR5148, 158 cours Fauriel, 42 033 Saint Etienne Cedex (France); Wasselin-Trupin, V. [Institut de Radioprotection et de Surete Nucleaire, BP. 17, 92 262 Fontenay aux Roses (France)

    2012-02-01

    In the framework of radioactive waste geological disposal, the long term evolution of the nuclear wastes packages and the release of the radionuclides from the wastes have to be studied. Regarding compacted wastes (cladding tubes) coming from reprocessing of spent fuel, the Zircaloy-4 (zirconium alloy) cladding tubes have been activated and oxidized in reactors. In the disposal, the radioactive waste is exposed to humid air in a first phase and to water after the resaturation phase. In order to better assess the degradation process of these nuclear waste package, the influence of wet air proton radiolysis on the behavior of surface oxidized Zircaloy-4 has been investigated. Radiolysis experiments were performed using an irradiation cell which is associated to an extracted beam. Samples are exposed to wet air, under and without radiolysis, during 12 and 24 h. The water partial pressure has been fixed at 6 and 50 mbar in order to have, respectively, localized adsorbed water molecules and a thin film of adsorbed water. Before and after each treatment, sample surfaces were characterized by X-ray Photoelectron Spectroscopy (XPS) in order to identify the elements at the topmost surface of the solid. The wet air radiolysis causes changes at the surface of oxidized Zircaloy-4 and influences the corrosion phenomenon. Indeed, an enrichment of tin and the presence of nitrogen species were observed. It could be due to the formation of tritin(II) tetrahydroxide dinitrate and a Zr{sup 4+} tetramer on the topmost oxide surface.

  19. Differential response of ammonia-oxidizing archaea and bacteria to the wetting of salty arid soil.

    Science.gov (United States)

    Sher, Yonatan; Ronen, Zeev; Nejidat, Ali

    2016-08-01

    Ammonia-oxidizing archaea and bacteria (AOA, AOB) catalyze the first and rate-limiting step of nitrification. To examine their differential responses to the wetting of dry and salty arid soil, AOA and AOB amoA genes (encoding subunit A of the ammonia monooxygenase) and transcripts were enumerated in dry (summer) and wet (after the first rainfall) soil under the canopy of halophytic shrubs and between the shrubs. AOA and AOB were more abundant under shrub canopies than between shrubs in both the dry and wetted soil. Soil wetting caused a significant decrease in AOB abundance under the canopy and an increase of AOA between the shrubs. The abundance of the archaeal amoA gene transcript was similar for both the wet and dry soil, and the transcript-to-gene ratios were amoA transcript-to-gene ratios were between 78 and 514. The lowest ratio was in dry soil under the canopy and the highest in the soil between the shrubs. The results suggest that the AOA are more resilient to stress conditions and maintain a basic activity in arid ecosystems, while the AOB are more responsive to changes in the biotic and abiotic conditions. PMID:27037935

  20. Wet oxidation of EDTA using metal-doped MCM-41 as catalyst

    International Nuclear Information System (INIS)

    Decontaminants like ethylenediaminetetraacetic acid (EDTA), ascorbic acid, and citric acid are widely used in the radioactive decontamination of reactor components. The complexants interfere in the treatment of radioactive effluent and hence it is imperative to oxidatively destroy the complexant to enable easy treatment of radioactive effluent. An attempt has been made to oxidatively destroy EDTA using hydrogen peroxide as oxidant in the presence of metal-doped MCM-41A as catalyst. The reason for using metal-doped MCM-41 as catalyst for the oxidative degradation is because of its larger surface area (∝ 1 000 m2 . g-1) with small pore size (20-100 Aa). Also the metal used has variable valency, which helps in undergoing electron transfer reactions. Metal-doped MCM-41 was synthesized. Results indicate that among the metals chosen for doping MCM-41, the catalytic efficiency in the oxidative degradation decreased in the following order: molybdenum > vanadium > titanium. (orig.)

  1. Effect of oxidizing agents on selenate formation in a wet FGD

    Energy Technology Data Exchange (ETDEWEB)

    Hiroyuki Akiho; Shigeo Ito; Hiromitsu Matsuda [Central Research Institute of Electric Power Industry (CRIEPI), Kanagawa (Japan). Energy Engineering Research Laboratory

    2010-09-15

    In a coal combustion process, a considerable amount of selenium is captured in the wet FGD, where it is oxidized from selenite to selenate, which is difficult to remove. Diethyl-p-phenylene-diammonium (DPD) absorptiometric analysis and ion chromatography identified peroxodisulfate ion (S{sub 2}O{sub 8}{sup 2-}) as the dominant oxidizing agent in the FGD liquor. Selenite was easily oxidized to selenate in the presence of S{sub 2}O{sub 8}{sup 2-} and the oxidation was accelerated as the temperature increased. Addition of Mn{sup 2+} ion was found to be effective in controlling selenate formation. When Mn{sup 2+} ion was added, oxidized not selenite to selenate but rather Mn{sup 2+} to MnO{sub 2}, which captured some dissolved selenite. 13 refs., 9 figs. 1 tab.

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

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

    International Nuclear Information System (INIS)

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

  4. Treatment of desizing wastewater from the textile industry by wet air oxidation

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper describes the application of wet air oxidation to the treatment of desizing wastewater from two textile companies. A two-liter high temperature, high pressure autoclave reactor was used in the study. The range of operating temperatures examined was between 150 and 290℃, and the partial pressure of oxygen ranged from 0. 375 to 2.25 MPa. Variations in pH,CODCr and TOD content were monitored during each experiment and used to assess the extent of conversion of the process. The effects of temperature, pressure and reaction time were explored extensively. More than 90 % CODCr reduction and 80 % TOC removal have been obtained. The results have also been demonstrated that WAO is a suitable pre-treatment methods due to improvement of the BOD5/CODCr ratio of desizing wastewater. The reaction kinetics of wet air oxidation of desizing wastewater has been proved to be two steps, a fast reaction followed by a slow reaction stage.

  5. Kinetics and Modelling of Glucose Wet Air Oxidation over Pd/C Catalyst.

    Czech Academy of Sciences Publication Activity Database

    Gogová, Zuzana; Zedníková, Mária; Hanika, Jiří

    Bratislava: Slovak Society of Chemical Engineering, 2007 - (Markoš, J.; Štefuca, V.), s. 309 ISBN 978-80-227-2640-5. [International Conference of Slovak Society of Chemical Engineering /34./. Tatranské Matliare (SK), 21.05.2007-25.05.2007] R&D Projects: GA ČR(CZ) GD203/03/H140 Institutional research plan: CEZ:AV0Z40720504 Keywords : glucose * wet air oxidation * kinetics Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  6. Toluene removal by oxidation reaction in spray wet scrubber: experimental, modeling and optimization

    OpenAIRE

    Roumporn Nikom; Juntima Chungsiriporn; Charun Bunyakan

    2006-01-01

    Toluene, an important volatile organic compound (VOC), is used in many kinds of industries, such as painting, printing, coating, and petrochemical industries. The emission of toluene causes serious air pollution, odor problem, flammability problem and affects human health. This paper proposes the removal of toluene from waste air using a spray wet scrubber combining the absorption and oxidation reaction. Aqueous sodium hypochlorite (NaOCl) solution was used as the scrubbing liquid in the syst...

  7. Kinetics of wet oxidation of phenol over an Fe/activated carbon catalyst

    NARCIS (Netherlands)

    Quintanilla, A.; Casas, J.A.; Rodriquez, J.J.; Kreutzer, M.T.; Kapteijn, F.; Moulijn, J.A.

    2007-01-01

    Wet oxidation of phenol over an Fe/activated carbon catalyst has been studied in a trickle-bed reactor in the following operational window: inlet C phenol=0.5 and 1 g/L, T=100-127 ºC, PT=3-8 atm, W=0-4.8 g, QL=0.125-2 mL/min and QO2=91.6 NmL/min. The experiments were carried out in the absence of ma

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

  10. Wet oxidation of phenol over transition metal oxide catalysts supported on Ce0.65 Zr0.35 O2 prepared by continuous hydrothermal synthesis in supercritical water.

    Science.gov (United States)

    Kim, Kyoung-Hun; Kim, Jeong-Rang; Ihm, Son-Ki

    2009-08-15

    The mixed oxide (Ce(0.65)Zr(0.35)O(2)) prepared by supercritical synthesis was applied as a support of transition metal (Mn, Fe, Co, Ni, and Cu) oxide catalysts for catalytic wet oxidation (CWO) of phenol in view of their higher thermal stability, better oxygen storage capacity, and higher surface area. The prepared catalysts showed an enhanced catalytic activity for CWO of phenol due to the excellent redox properties of ceria-zirconia mixed oxide. Among the prepared catalysts, the CuO(x)/Ce(0.65)Zr(0.35)O(2) was the most effective catalyst in view of catalytic activity and CO(2) selectivity. The leached copper ions seem to contribute to the higher conversion of phenol over the CuO(x)/Ce(0.65)Zr(0.35)O(2) via homogeneous catalysis. The characterization with XPS, XANES, and TPR experiments confirmed that the active copper species in the CuO(x)/Ce(0.65)Zr(0.35)O(2) is highly dispersed Cu(2+) clusters. Although the MnO(x)/Ce(0.65)Zr(0.35)O(2) showed a high conversion of phenol and TOC, the converted phenol was mainly changed to carbon deposits on the surface of catalyst resulting in catalyst deactivation. PMID:19264401

  11. Fe-Al-Pillared Clays: Catalysts for Wet Peroxide Oxidation of Phenol

    Science.gov (United States)

    Guélou, Erwan; Tatibouët, Jean-Michel; Barrault, Joël

    Catalytic phenol oxidation with hydrogen peroxide (CWPO) was performed over iron containing clays, pillared with Al or mixed Fe-Al complexes. This study deals with the better conditions for the oxidation reaction (temperature, pH, hydrogen peroxide concentration, atmosphere, etc.) in the presence of homogeneous or heterogeneous catalysts. The reaction was performed in a dynamic fixed-bed reactor, which gave the effect of the main experimental variables and an estimation of the kinetic parameters. The catalysts were characterized by classical techniques and by electron spin resonance (ESR). From ESR experiments the reaction mechanism involving hydroxyl radicals was also investigated.

  12. Development and testing of a wet oxidation waste processing system. [for waste treatment aboard manned spacecraft

    Science.gov (United States)

    Weitzmann, A. L.

    1977-01-01

    The wet oxidation process is considered as a potential treatment method for wastes aboard manned spacecraft for these reasons: (1) Fecal and urine wastes are processed to sterile water and CO2 gas. However, the water requires post-treatment to remove salts and odor; (2) the residual ash is negligible in quantity, sterile and easily collected; and (3) the product CO2 gas can be processed through a reduction step to aid in material balance if needed. Reaction of waste materials with oxygen at elevated temperature and pressure also produces some nitrous oxide, as well as trace amounts of a few other gases.

  13. Wet oxidation lumped kinetic model for wastewater organic burden biodegradability prediction.

    Science.gov (United States)

    Verenich, Svetlana; Kallas, Juha

    2002-08-01

    In many cases, treatment of wastewaters requires a combination of processes that very often includes biological treatment. Wet oxidation (WO) in combination with biotreatment has been successfully used for the treatment of refractory wastes. Therefore, information about the biodegradability of wastewater solutes and particulates after wet oxidation is very important. The present work proposes a model that can describe the oxidation process via organic concentration characteristics such as chemical oxygen demand (COD), biochemical oxygen demand (BOD), and immediately available BOD (IA BOD) and so can allow the prediction of biodegradability (i.e., BOD/COD ratio). The reaction mechanism includes the destruction of nonbiodegradable substances bytwo pathways: oxidation to carbon dioxide and water and oxidation to larger biodegradable compounds with their further degradation to smaller ones measured via IA BOD. The destruction of small biodegradable compounds to end products is also included in the model. The experiments were performed at different temperatures (170-200 degrees C) and partial oxygen pressures (0.5-1.5 MPa) in a batch stainless steel high-pressure autoclave. The model of concentrated thermomechanical pulp circulation water was selected for the experiments. The proposed model correlates with the experimental data well and it is compared with other WO models in the literature. PMID:12188362

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

    Czech Academy of Sciences Publication Activity Database

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

    2005-01-01

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

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

    OpenAIRE

    VENNESTROM, PETER NICOLAI RAVNBORG

    2014-01-01

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

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

    International Nuclear Information System (INIS)

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

  17. Biodiesel by catalytic reactive distillation powered by metal oxides

    NARCIS (Netherlands)

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

    2008-01-01

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

  18. ESR ST study of hydroxyl radical generation in wet peroxide system catalyzed by heterogeneous ruthenium

    NARCIS (Netherlands)

    Rokhina, E.V.; Golovina, E.A.; As, van H.; Virkutyte, J.

    2009-01-01

    Ru-based catalysts gained popularity because of their applicability for a variety of processes, including carbon monoxide oxidation, wet air catalytic oxidation and wastewater treatment. The focus of a current study was generation of hydroxyl radicals in the wet peroxide system catalyzed by heteroge

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Kim, Sang Chai; Shim, Wang Geun

    2008-06-15

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Professor Francisco Zaera

    2007-08-09

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

  3. Influence of Substrate Particle Size and Wet Oxidation on Physical Surface Structures and Enzymatic Hydrolysis of Wheat Straw

    DEFF Research Database (Denmark)

    Pedersen, Mads; Meyer, Anne S.

    2009-01-01

    microscopy images of the straw particles revealed edged, nonspherical, porous particles with variable surface structures as a result of the grinding. Wet oxidation pretreatment tore up the surface structures of the particles to retain vascular bundles of xylem and phloem. The enzymatic hydrolysis left behind......In the worldwide quest for producing biofuels from lignocellulosic biomass, the importance of the substrate pretreatment is becoming increasingly apparent. This work examined the effects of reducing the substrate particle sizes of wheat straw by grinding prior to wet oxidation and enzymatic...... hydrolysis. The yields of glucose and xylose were assessed after treatments with a benchmark cellulase system consisting of Celluclast 1.5 L (Trichoderma reesei) and Novozym 188 -glucosidase (Aspergillus niger). Both wet oxidized and not wet oxidized wheat straw particles gave increased glucose release with...

  4. High Temperature Behavior of Oxidized Mild Steel in Dry and Wet Atmospheres

    International Nuclear Information System (INIS)

    During the hot rolling process, steels develop an oxide scale on their surface. This scale can affect the mechanical properties of the rolled steel and its surface aspect. The main problem comes from the mechanical integrity of the oxide scales which could delaminate or crack, leading eventually to later oxide incrustation within the steel. The objective of the present work is to qualify the mechanical integrity of the iron oxide scales during the hot rolling process. The laboratory experiments use a four point bending test to simulate the mechanical solicitation which takes place during the rolling sequence of the steel slabs. The oxide scales grow on a mild steel at 900 .deg. C under wet or dry atmosphere and the oxidized steel is then mechanically tested at 900 .deg. C or 700 .deg. C. The high temperature four point bending tests are completed with microstructural observations and with the record of acoustic emission to follow in-situ the mechanical damages of the oxide scales. The results show the role of water vapor which promotes the scale adherence, and the role of the temperature as the oxide are more damaged at 700 .deg. C than at 900 .deg. C

  5. Study on dynamics characteristics of wet air oxidation of non-ionic surfactants

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Wet air oxidation is an effective method to deal with highly concentrated nondegradable emulsification wastewater which contains non-ionic surfactants. This article illustrates our investigation on dynamic characteristics of wet air oxidation of typical non-ionic surfactants like polyether, phenol ether and widely used alcohol ether. The experimental results indicated that the oxidation rate of polyether, phenol ether and alcohol ether obviously ascended as the temperature rose. A good oxidation effect was available at 240℃. The TOC removal rate could reach 88.0%, 94% and 91.5%, after 125 min reaction. Alcohol ether was prone to an easier oxidation compared with polyether and phenol ether when the temperature was 220℃ or below. The oxidation rate of alcohol ether was higher than that of polyether at 160℃, while the oxidation rate of polyether was higher than that of phenol ether between 180℃ and 220℃. During the later period of the reaction at 240℃, the rate of phenol ether was higher than that of alcohol ether, which was still higher than that of polyether. Partitioned first order kinetics model analy-sis showed that the apparent activation energy of alcohol ether was lower than that of both polyether and phenol ether in the leading stage and lagging stage, and it was easy to acquire a higher oxidation rate for alcohol ether at low temperature. Three parameter general dynamics model analyses showed that the reason why the oxidation rate of polyether was lower than that of alcohol ether was that the oxidation of polyether was more apt to be converted to intermediate production than that of alcohol ether, whereas between 200℃ and 220℃, the direct oxidation rate of polyether and the oxidation rate of intermediate product were obviously lower than that of alcohol ether. The apparent activation energy of direct and indirect oxidation of polyether was 43.37 and 60.45 kJ?mol?1, respectively, while the corre-sponding apparent activation energy of alcohol

  6. Study on dynamics characteristics of wet air oxidation of non-ionic surfactants

    Institute of Scientific and Technical Information of China (English)

    ZENG XinPing; TANG WenWei; ZHAO JianFu; GU GuoWei

    2008-01-01

    Wet air oxidation is an effective method to deal with highly concentrated nondegradable emulsification wastewater which contains non-ionic surfactants. This article illustrates our investigation on dynamic characteristics of wet air oxidation of typical non-ionic surfactants like polyether, phenol ether and widely used alcohol ether. The experimental results indicated that the oxidation rate of polyether, phenol ether and alcohol ether obviously ascended as the temperature rose. A good oxidation effect was available at 240℃. The TOC removal rate could reach 88.0%, 94% and 91.5%, after 125 min reaction. Alcohol ether was prone to an easier oxidation compared with polyether and phenol ether when the temperature was 220℃ or below. The oxidation rate of alcohol ether was higher than that of polyether at 160℃, while the oxidation rate of polyether was higher than that of phenol ether between 180℃ and 220℃. During the later period of the reaction at 240℃, the rate of phenol ether was higher than that of alcohol ether, which was still higher than that of polyether. Partitioned first order kinetics model analysis showed that the apparent activation energy of alcohol ether was lower than that of both polyether and phenol ether in the leading stage and lagging stage, and it was easy to acquire a higher oxidation rate for alcohol ether at low temperature. Three parameter general dynamics model analyses showed that the reason why the oxidation rate of polyether was lower than that of alcohol ether was that the oxidation of polyether was more apt to be converted to intermediate production than that of alcohol ether, whereas between 200℃ and 220℃, the direct oxidation rate of polyether and the oxidation rate of intermediate product were obviously lower than that of alcohol ether. The apparent activation energy of direct and indirect oxidation of polyether was 43.37 and 60.45 kJ·mol-1, respectively, while the corresponding apparent activation energy of alcohol

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-01

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

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

    Science.gov (United States)

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

    2014-04-01

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

  10. CO catalytic oxidation on iron-embedded monolayer MoS2

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-15

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2014-06-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    罗伟平; 刘大为; 孙俊; 邓伟; 盛文兵; 刘强; 郭灿城

    2014-01-01

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

  17. Real-time in situ monitoring of wet thermal oxidation for precise confinement in VCSELs

    International Nuclear Information System (INIS)

    A new imaging method is presented enabling the monitoring of the lateral wet thermal oxidation of a thin Al-containing layer embedded in a vertical cavity lasers (VCSEL) structure. This method is based on the measurement of the modification of the VCSEL reflectivity spectrum inherent to the aperture layer refractive index change, with an observation window restricted to the wavelength ranges for which this reflectivity variation is maximal. The main purpose is the accurate control of the buried confinement aperture, and, thereby, that of the electro-optical characteristics of the laser device. The kinetics of the lateral oxidation has been studied for small-size aperture VCSEL (3–10 µm) and for long-range oxidation depths. This straightforward method based on an optical imaging system will enable robust improvement of the production yield of this multifactor-dependent technological process

  18. Chloride interference in the analysis of dissolved organic carbon by the wet oxidation method

    Science.gov (United States)

    Aiken, G.R.

    1992-01-01

    The presence of Cl- in concentrations greater than 0.02 M is shown to interfere with the analysis of aqueous DOC concentrations by the wet oxidation method of analysis when a reaction time of 5 min is employed. Chloride competes with DOC for S2O82-, lowering the overall oxidation efficiency. The resulting HOCl from the oxidation of Cl- reacts with DOC, producing significant amounts of chlorinated intermediate compounds in addition to CO2. These compounds were found in the waste effluent from the reaction chamber and in the gas stream transporting CO2 to the detector. While a possible Cl- effect has been noted for DOC measurements in the past, it has not previously been demonstrated to be a source of error at the concentrations reported in this paper. The interference can be overcome either by increasing the digestion time or by diluting samples to contain less than 0.02 M Cl-.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-01

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

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

    Science.gov (United States)

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

    2016-06-22

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

  1. Supported manganese oxide on TiO{sub 2} for total oxidation of toluene and polycyclic aromatic hydrocarbons (PAHs): Characterization and catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Aboukaïs, Antoine, E-mail: aboukais@univ-littoral.fr [Univ Lille Nord de France, 59000 Lille (France); Equipe Catalyse, UCEIV, EA 4492, MREI, ULCO, 59140 Dunkerque (France); Abi-Aad, Edmond [Univ Lille Nord de France, 59000 Lille (France); Equipe Catalyse, UCEIV, EA 4492, MREI, ULCO, 59140 Dunkerque (France); Taouk, Bechara [Laboratoire de Sécurité des procédés Chimiques (LSPC), EA 4704, INSA Rouen, Avenue de l' Université, 76801 Saint Etienne du Rouvray (France)

    2013-11-01

    Manganese oxide catalysts supported on titania (TiO{sub 2}) were prepared by incipient wetness impregnation method in order to elaborate catalysts for total oxidation of toluene and PAHs. These catalysts have been characterized by means of X-ray diffraction (XRD), electron paramagnetic resonance (EPR), temperature programmed reduction (TPR) and temperature programmed desorption (TPD). It has been shown that for the 5%Mn/TiO{sub 2} catalyst the reducibility and the mobility of oxygen are higher compared, in one side, to other x%Mn/TiO{sub 2} samples and, in another side, to catalysts where TiO{sub 2} support was replaced by γ-Al{sub 2}O{sub 3} or SiO{sub 2}. It has been shown that the content of manganese loading on TiO{sub 2} has an effect on the catalytic activity in the toluene oxidation. A maximum of activity was obtained for the 5%Mn/TiO{sub 2} catalyst where the total conversion of toluene was reached at 340 °C. This activity seems to be correlated to the presence of the Mn{sup 3+}/Mn{sup 4+} redox couple in the catalyst. When the Mn content increases, large particles of Mn{sub 2}O{sub 3} appear leading then to the decrease in the corresponding activity. In addition, compared to both other supports, TiO{sub 2} seems to be the best to give the best catalytic activity for the oxidation of toluene when it is loaded with 5% of manganese. For this reason, the latter catalyst was tested for the abatement of some PAHs. The light off temperature of PAHs compounds increases with increasing of benzene rings number and with decreasing of H/C ratio. All of PAHs are almost completely oxidized and converted at temperatures lower than 500 °C. - Highlights: • Preparation of x%MnO{sub 2}/TiO{sub 2} catalysts. • Catalytic oxidation tests of toluene and PAHs. • EPR, TPR and TPD characterizations of Mn(II) and Mn(IV) ions.

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

    Directory of Open Access Journals (Sweden)

    Ghorban Asgari

    2014-12-01

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

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

    Institute of Scientific and Technical Information of China (English)

    唐文翔; 武晓峰; 刘刚; 李双德; 李东艳; 李文辉; 陈运法

    2015-01-01

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

  4. Full-Scale Testing of a Mercury Oxidation Catalyst Upstream of a Wet FGD System

    Energy Technology Data Exchange (ETDEWEB)

    Gary Blythe; Jennifer Paradis

    2010-06-30

    This document presents and discusses results from Cooperative Agreement DE-FC26-06NT42778, 'Full-scale Testing of a Mercury Oxidation Catalyst Upstream of a Wet FGD System,' which was conducted over the time-period July 24, 2006 through June 30, 2010. The objective of the project was to demonstrate at full scale the use of solid honeycomb catalysts to promote the oxidation of elemental mercury in pulverized-coal-fired flue gas. Oxidized mercury is removed downstream in wet flue gas desulfurization (FGD) absorbers and collected with the byproducts from the FGD system. The project was co-funded by EPRI, the Lower Colorado River Authority (LCRA), who also provided the host site, Great River Energy, Johnson Matthey, Southern Company, Salt River Project (SRP), the Tennessee Valley Authority (TVA), NRG Energy, Ontario Power and Westar. URS Group was the prime contractor and also provided cofunding. The scope of this project included installing and testing a gold-based catalyst upstream of one full-scale wet FGD absorber module (about 200-MW scale) at LCRA's Fayette Power Project (FPP) Unit 3, which fires Powder River Basin coal. Installation of the catalyst involved modifying the ductwork upstream of one of three wet FGD absorbers on Unit 3, Absorber C. The FGD system uses limestone reagent, operates with forced sulfite oxidation, and normally runs with two FGD modules in service and one spare. The full-scale catalyst test was planned for 24 months to provide catalyst life data. Over the test period, data were collected on catalyst pressure drop, elemental mercury oxidation across the catalyst module, and mercury capture by the downstream wet FGD absorber. The demonstration period began on May 6, 2008 with plans for the catalyst to remain in service until May 5, 2010. However, because of continual increases in pressure drop across the catalyst and concerns that further increases would adversely affect Unit 3 operations, LCRA decided to end the

  5. Wet oxidative degradation of cellulosic wastes 5- chemical and thermal properties of the final waste forms

    International Nuclear Information System (INIS)

    In this study, the residual solution arising from the wet oxidative degradation of solid organic cellulosic materials, as one of the component of radioactive solid wastes, using hydrogen peroxide as oxidant. Were incorporated into ordinary Portland cement matrix. Leaching as well as thermal characterizations of the final solidified waste forms were evaluated to meet the final disposal requirements. Factors, such as the amount of the residual solution incorporated, types of leachant. Release of different radionuclides and freezing-thaw treatment, that may affect the leaching characterization. Were studied systematically from the data obtained, it was found that the final solid waste from containing 35% residual solution in tap water is higher than that in ground water or sea water. Based on the data obtained from thermal analysis, it could be concluded that incorporating the residual solution form the wet oxidative degradation of cellulosic materials has no negative effect on the hydration of cement materials and consequently on the thermal stability of the final solid waste from during the disposal process

  6. An analytical method for 14C in environmental water based on a wet-oxidation process.

    Science.gov (United States)

    Huang, Yan-Jun; Guo, Gui-Yin; Wu, Lian-Sheng; Zhang, Bing; Chen, Chao-Feng; Zhang, Hai-Ying; Qin, Hong-Juan; Shang-Guan, Zhi-Hong

    2015-04-01

    An analytical method for (14)C in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic (14)C in environmental water, or total (14)C, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic (14)C can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of (14)C in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%-99.0% with a mean of 98.9(± 0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(± 2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for (14)C analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities. PMID:25590997

  7. An analytical method for 14C in environmental water based on a wet-oxidation process

    International Nuclear Information System (INIS)

    An analytical method for 14C in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic 14C in environmental water, or total 14C, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic 14C can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of 14C in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%–99.0% with a mean of 98.9(±0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(±2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for 14C analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities. - Highlights: • An analytical method of 14C in environmental water was developed. • Extraction or recovery experiments were conducted with excellent results. • Verification and uncertainty assessment was presented

  8. Hydrogen content of underwater wet welds deposited by rutile and oxidizing electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pope, A.M. [PETROBRAS Research and Development Center, Rio de Janeiro (Brazil); Liu, S. [Colorado School of Mines, Golden, CO (United States). Center for Welding, Joining and Coatings Research

    1996-12-01

    Shielded metal arc wet welding, due to its flexibility and ease of mobilization, is one of the most attractive methods for repair of underwater structures. However, the quality of the weld metals deposited by this process is detrimentally affected by the direct contact of the welding arc with the aqueous environment. Oxygen and hydrogen generated by the decomposition of water in the arc are responsible for the main problems related to this specific process: loss of deoxidizers, oxygen pickup, increase in oxide inclusions content, hydrogen-induced cracking, and porosity. Rutile electrodes are recognized in the literature as being able to deposit welds with adequate mechanical properties but with high hydrogen content. Oxidizing electrodes, on the other hand, are able to deposit welds with lower hydrogen content but higher oxygen content. Welds deposited by rutile electrodes presented approximately 90 ml/100g of diffusible hydrogen while oxidizing electrodes produced welds with diffusible hydrogen contents varying from 40 to 50 ml/100g. It was found that the measured diffusible hydrogen contents of underwater wet welds are more dependent on the type of electrode covering than on the weld metal oxygen content. The residual hydrogen content of underwater welds showed a tendency to increase to a constant level of approximately 5 ml/100g as the oxygen content of the weld increased to the saturation value (0.22 wt.pct.). It seems, therefore, that the diffusible hydrogen content of underwater wet welds is more influenced by the amount of total hydrogen absorbed by the liquid metal before solidification than by the amount of inclusions, acting as hydrogen traps, in the weld metal.

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

    Science.gov (United States)

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

    2015-08-01

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

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

    International Nuclear Information System (INIS)

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

  11. Surface activation of thin silicon oxides by wet cleaning and silanization

    International Nuclear Information System (INIS)

    Silanization protocols for glass slides and silicon oxide substrates usually include acid rinsing steps to activate the surfaces prior to silanization. In our group, field-effect transistor devices and electrolyte-insulator-semiconductor structures are used to electronically record signals from cells or to detect biomolecular interactions at the solid-liquid interface. A miniaturized, high sensitive, field-effect-based semiconductor device should expose at its input stage just a thin oxide (< 10 nm) to the electrolyte solution. Therefore, silanization protocols are needed, which do not alter the thin oxide layers in terms of topology changes or thickness loss. In this article we evaluated different protocols for wet cleaning and activation of thin silicon oxides. The efficiency of the cleaning methods was verified with Contact Angle Measurements, Atomic Force Microscopy, and Fourier-Transform Infrared Spectroscopy. Furthermore, X-ray Photoelectron Spectroscopy was used to characterize the oxides after the cleaning and silanization procedures. (3-aminopropyl)triethoxysilane was used to functionalize the oxide surfaces for further attachment of biological molecules (e.g. proteins, DNA). Thicknesses and uniformity of the silane coatings were evaluated by Imaging Ellipsometry

  12. Ethanol production from wet oxidized corn straw by simultaneous saccharification and fermentation

    DEFF Research Database (Denmark)

    Zhang, Q.; Yin, Y.; Thygesen, Anders;

    2010-01-01

    In order to find out the appropriate process for ethanol production from corn straw, alkaline wet-oxidation pretreatment (195°C, 15 min, Na2CO3 2 g/L, O2 1200 kPa) and simultaneous saccharification and fermentation (SSF) were adopted to produce ethanol. The results showed that 90% of cellulose...... obtained. The estimated total ethanol production was 262.7 kg/t raw material by assuming the consumption of both C-6 and C-5. No obvious inhibition effect occurred during SSF. These offered experiment evidences for ethanol production from corn straw....

  13. Pretreatment of corn stover using wet oxidation to enhance enzymatic digestibility

    DEFF Research Database (Denmark)

    Varga, E.; Schmidt, A.S.; Reczey, K.;

    2003-01-01

    Corn stover is an abundant, promising raw material for fuel ethanol production. Although it has a high cellulose content, without pretreatment it resists enzymatic hydrolysis, like most lignocellulosic materials. Wet oxidation (water, oxygen, mild alkali or acid, elevated temperature and pressure......) was investigated to enhance the enzymatic digestibility of corn stover. Six different combinations of reaction temperature, time, and pH were applied. The best conditions (60 g/L of corn stover, 195degreesC, 15 min, 12 bar O-2, 2 g/L of Na2CO) increased the enzymatic conversion of corn stover four...

  14. Spin-on metal oxide materials with high etch selectivity and wet strippability

    Science.gov (United States)

    Yao, Huirong; Mullen, Salem; Wolfer, Elizabeth; McKenzie, Douglas; Rahman, Dalil; Cho, JoonYeon; Padmanaban, Munirathna; Petermann, Claire; Hong, SungEun; Her, YoungJun

    2016-03-01

    Metal oxide or metal nitride films are used as hard mask materials in semiconductor industry for patterning purposes due to their excellent etch resistances against the plasma etches. Chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques are usually used to deposit the metal containing materials on substrates or underlying films, which uses specialized equipment and can lead to high cost-of-ownership and low throughput. We have reported novel spin-on coatings that provide simple and cost effective method to generate metal oxide films possessing good etch selectivity and can be removed by chemical agents. In this paper, new spin-on Al oxide and Zr oxide hard mask formulations are reported. The new metal oxide formulations provide higher metal content compared to previously reported material of specific metal oxides under similar processing conditions. These metal oxide films demonstrate ultra-high etch selectivity and good pattern transfer capability. The cured films can be removed by various chemical agents such as developer, solvents or wet etchants/strippers commonly used in the fab environment. With high metal MHM material as an underlayer, the pattern transfer process is simplified by reducing the number of layers in the stack and the size of the nano structure is minimized by replacement of a thicker film ACL. Therefore, these novel AZ® spinon metal oxide hard mask materials can potentially be used to replace any CVD or ALD metal, metal oxide, metal nitride or spin-on silicon-containing hard mask films in 193 nm or EUV process.

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

    Science.gov (United States)

    Liu, Di-Jia

    2010-02-23

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Czech Academy of Sciences Publication Activity Database

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

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

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

    Czech Academy of Sciences Publication Activity Database

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

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

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

    Czech Academy of Sciences Publication Activity Database

    Gaálová, Jana; Kaluža, Luděk; Topka, Pavel

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

  4. Bulk Preparation of Holey Graphene via Controlled Catalytic Oxidation

    Science.gov (United States)

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

    2015-01-01

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

  5. Effect of SUS316L stainless steel surface conditions on the wetting of molten multi-component oxides ceramic

    International Nuclear Information System (INIS)

    Highlights: • Multi-component oxides had a good wetting on stainless substrates with pretreatments. • Various substrates surface roughness caused the difference of final contact angles. • The wetting rate was slow on polished substrate due to the slow surface oxidation. - Abstract: A study on the effect of SUS316L stainless steel surface conditions on the wetting behavior of molten multi-component oxides ceramic was performed and aimed to contribute to the further understanding of the application of oxides ceramic in penetration treatment of stainless steel coatings and the deposition of stainless steel cermet coatings. The results show that at 1273 K, different surface pre-treatments (polishing and heating) had an important effect on the wetting behavior. The molten multi-component oxides showed good wettability on both stainless steel substrates, however, the wetting process on the polished substrate was significantly slower than that on the heated substrates. The mechanism of the interfacial reactions was discussed based on the microscopic and thermodynamic analysis, the substrates reacted with oxygen generated from the decomposition of the molten multi-component oxides and oxygen contained in the argon atmosphere, and the oxide film caused the molten multi-component oxides ceramic to spread on the substrates surfaces. For the polished substrate, more time was required for the surface oxidation to reach the surface composition of Heated-S, which resulted in relatively slow spreading and wetting rates. Moreover, the variance of the surface roughness drove the final contact angles to slightly different values following the sequence Polished-S > Heated-S

  6. Effect of SUS316L stainless steel surface conditions on the wetting of molten multi-component oxides ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jin, E-mail: wangjinustb@gmail.com [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, 808-0196 (Japan); Matsuda, Nozomu [Bar and Wire Product Unit, Nippon steel and Sumitomo Metal Corporation, Fukuoka, 802-8686 (Japan); Shinozaki, Nobuya [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, 808-0196 (Japan); Miyoshi, Noriko [The Center for Instrumental Analysis, Kyushu Institute of Technology, Fukuoka, 804-8550 (Japan); Shiraishi, Takanobu [Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588 (Japan)

    2015-02-01

    Highlights: • Multi-component oxides had a good wetting on stainless substrates with pretreatments. • Various substrates surface roughness caused the difference of final contact angles. • The wetting rate was slow on polished substrate due to the slow surface oxidation. - Abstract: A study on the effect of SUS316L stainless steel surface conditions on the wetting behavior of molten multi-component oxides ceramic was performed and aimed to contribute to the further understanding of the application of oxides ceramic in penetration treatment of stainless steel coatings and the deposition of stainless steel cermet coatings. The results show that at 1273 K, different surface pre-treatments (polishing and heating) had an important effect on the wetting behavior. The molten multi-component oxides showed good wettability on both stainless steel substrates, however, the wetting process on the polished substrate was significantly slower than that on the heated substrates. The mechanism of the interfacial reactions was discussed based on the microscopic and thermodynamic analysis, the substrates reacted with oxygen generated from the decomposition of the molten multi-component oxides and oxygen contained in the argon atmosphere, and the oxide film caused the molten multi-component oxides ceramic to spread on the substrates surfaces. For the polished substrate, more time was required for the surface oxidation to reach the surface composition of Heated-S, which resulted in relatively slow spreading and wetting rates. Moreover, the variance of the surface roughness drove the final contact angles to slightly different values following the sequence Polished-S > Heated-S.

  7. Treatment of toxic and hazardous organic wastes by wet oxidation process with oxygenated water at low temperature

    International Nuclear Information System (INIS)

    The wet oxidation process using air or molecular oxygen is a well-known process from long time. It is suitable to oxidize several types of waste refractory to the usual biological, thermal and chemical treatments. The drastic operating conditions (high pressures and temperatures) prevented its industrial development. In the last years a new interest was assigned to the process for the treatment of nuclear wastes (organic resins and exhaust organic wastes); the treatment is carried out at widely reduced operating conditions (atmospheric pressure and boiling temperature) by means of metallic catalysts and hydrogen peroxide. With some limits, the wet oxidation with hydrogen peroxide at low temperature can be applied to conventional waste waters containing toxic organic compounds. In the present report are summarized the activities developed at ENEA Fuel Cycle Department by the task force 'Deox' constituted by laboratory and plant specialists in order to verify the application of the wet oxidation process to the treatment of the toxic wastes. (author)

  8. Biodegradability enhancement by wet oxidation in alkaline media: delignification as a case study.

    Science.gov (United States)

    Verenich, S; Kallas, J

    2002-06-01

    Nowadays many industries are considering the recycling of process waters as a way of improving environmental safety, preventing pollution, and avoiding the loss of valuable production materials. One industry in the forefront of this trend is the pulp and paper industry. Lignin is a pollutant present in the mill process waters and such macromolecules can cause problems during biological treatment of process waters. Wet oxidation (WO) is a process that can be used as a pre-treatment method for lignin fragmentation and improvement of biodegradability. Wet oxidation (WO) under alkaline conditions permits faster lignin fragmentation than the conventional WO process and, therefore, should favour biodegradability improvement. In this study, the experiments were carried out in a high-pressure batch reactor with an alkali lignin solution at temperatures up to 438 K, an alkali concentration of 1.5-3.5 g l(-1) and an oxygen partial pressure of 0.4 to 1.5 MPa. At an alkali concentration of 3.5 g l(-1)1 and 0.4 MPa of oxygen partial pressure, an increase in BOD/COD ratio was achieved from an initial 11% to 71%. The experiments also showed that the amount of small molecules in the solution measured by Immediately Available BOD (IA BOD) depends on the amount of alkali added and the operating temperature. PMID:12118617

  9. Treatment of desizing wastewater from the textile industry by wet air oxidation

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper describes the application of wet air oxidation to the treatment of desizing wastewater from two textile companies. A two-liter high temperature, high pressure autoclave reactor was used in the study. The range of operating temperatures examined was between 150 and 290℃, and the partial pressure of oxygen ranged from 0. 375 to 2.25 MPa. Variations in pH,CODCr and TOD content were monitored during each experiment and used to assess the extent of conversion of the process. The effects of temperature, pressure and reaction time were explored extensively. More than 90 % CODCr reduction and 80 % TOC removal have been obtained. The results have also been demonstrated that WAO is a suitable pre-treatment methods due to improvement of the BOD5/CODCr ratio of desizing wastewater. The reaction kinetics of wet air oxidation of desizing wastewater has been proved to be two steps, a fast reaction followed by a slow reaction stage.

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

    KAUST Repository

    Hong, Jongsup

    2013-10-01

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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  12. Degradation of H-acid in aqueous solution by microwave assisted wet air oxidation using Ni-loaded GAC as catalyst

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yao-bin; QUAN Xie; ZHAO Hui-min; CHEN Shuo; YANG Feng-lin

    2005-01-01

    A novel process, microwave assisted catalytic wet air oxidation(MW-CWO), was applied for the degradation of H-acid( 1-amino8-naphthol-3, 6-disulfonic acid) in aqueous solution. Ni-loaded granular activated carbon (GAG), prepared by immersion-calcination method, was used as catalyst. The results showed that the MW-CWO process was very effective for the degradation of H-acid in aqueous solution under atmospheric pressure with 87.4% TOC (total organic carbon) reduction in 20 min. Ni on GAC existed in the form of NiO as specified by XRD. Loss of Ni was significant in the initial stage, and then remained almost constant after 20 min reaction. BET surface area results showed that the surface property of GAC after MW-CWO process was superior to that of blank GAC.

  13. Catalytic oxidative conversion of alkanes to olefines and oxygenates

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

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

    Science.gov (United States)

    Töpfer, Kai; Tremblay, Jean Christophe

    2016-07-21

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

  16. Effect of nitrogen doping on wetting and photoactive properties of laser processed zinc oxide-graphene oxide nanocomposite layers

    Energy Technology Data Exchange (ETDEWEB)

    György, E., E-mail: egyorgy@icmab.es [Consejo Superior de Investigaciones Cientificas, Instituto de Ciencia de Materiales de Barcelona (CSIC-ICMAB), Campus UAB, 08193 Bellaterra (Spain); National Institute for Lasers, Plasma and Radiation Physics, P. O. Box MG 36, 76900 Bucharest V (Romania); Pérez del Pino, A. [Consejo Superior de Investigaciones Cientificas, Instituto de Ciencia de Materiales de Barcelona (CSIC-ICMAB), Campus UAB, 08193 Bellaterra (Spain); Logofatu, C. [National Institute for Materials Physics, P. O. Box MG. 7, 77125 Bucharest (Romania); Duta, A.; Isac, L. [Transilvania University of Brasov, Research Centre for Renewable Energy Systems and Recycling, Eroilor 29, 500036, Brasov (Romania)

    2014-07-14

    Zinc oxide-graphene oxide nanocomposite layers were submitted to laser irradiation in air or controlled nitrogen atmosphere using a frequency quadrupled Nd:YAG (λ = 266 nm, τ{sub FWHM} ≅ 3 ns, ν = 10 Hz) laser source. The experiments were performed in air at atmospheric pressure or in nitrogen at a pressure of 2 × 10{sup 4} Pa. The effect of the irradiation conditions, incident laser fluence value, and number of subsequent laser pulses on the surface morphology of the composite material was systematically investigated. The obtained results reveal that nitrogen incorporation improves significantly the wetting and photoactive properties of the laser processed layers. The kinetics of water contact angle variation when the samples are submitted to laser irradiation in nitrogen are faster than that of the samples irradiated in air, the surfaces becoming super-hydrophilic under UV light irradiation.

  17. On ultra-thin oxide/Si and very-thin oxide/Si structures prepared by wet chemical process

    International Nuclear Information System (INIS)

    The properties of ultra-thin oxide/Si and very-thin oxide/Si structures prepared by wet chemical oxidation in nitric acid aqueous solutions (NAOS) and passivated in HCN aqueous solutions were investigated by electrical, optical and structural methods. n- and p-doped (1 0 0) crystalline Si substrates were used. There were identified more types of interface defect states in dependence on both post-oxidation treatment and passivation procedure. On samples prepared on n-type Si, continuous spectrum of defect states of 0.05-0.2 eV range and discrete defect traps, ∼ECB - 0.26 eV and ∼ECB - 0.39 eV, were found. All mentioned defects are related with various types of Si dangling bonds and/or with SiOx precipitates. Post-metallization annealing of investigated MOS structures reduced the interface defect density and suppressed the leakage currents. It did not change spectral profile of interface defect states in the Si band gap. In addition, there are presented following two optical phenomena: relation between amplitude of photoluminescence signal of NAOS samples and parameters of chemical oxidation process and quantum confinement effect observed on samples containing Si grains of size less as ∼2 nm.

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

    Czech Academy of Sciences Publication Activity Database

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

    2011-01-01

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

  19. A PROCESS FOR THE CATALYTIC OXIDATION OF HYDROCARBONS

    DEFF Research Database (Denmark)

    1999-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2004-01-01

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

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

    Science.gov (United States)

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

    2015-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-15

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2012-04-21

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

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

    Indian Academy of Sciences (India)

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

    2011-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-10-20

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

  8. Catalytic oxidative treatment of diluted black liquor at mild conditions using copper oxide/cerium oxide catalyst.

    Science.gov (United States)

    Garg, Anurag; Mishra, Indra M; Chand, Shri

    2008-02-01

    Wet-air oxidation of diluted black liquor (chemical oxygen demand [COD] approximately 3250 to 14 500 mg/L) was performed at mild operating conditions (temperature = 388 to 423 K and total pressure = 0.6 MPa) in the presence of heterogeneous 60% copper oxide (CuO)/ 40% cerium oxide (CeO2) catalyst. Maximum COD reduction of 77.3% was obtained at 423 K at pH 3.0, which was marginally higher than that obtained at 413 K temperature (77.1%). In the acidic environment (pH < or = 3), most of the COD was removed in the form of settleable solids during the transient heating of the wastewater from room temperature to the desired one. The solid residue obtained after the reaction has a heating value of 20.1 MJ/kg, which is comparable with that of Indian coal. Thermal degradation kinetic determination suggested that thermal characteristics of the solid residue are well represented by a power law model with Agarwal and Sivasubramanian approximation (Safi et al., 2004). PMID:18330223

  9. Oxidation of a novel CeO{sub 2}-dispersed chromium coating in wet air

    Energy Technology Data Exchange (ETDEWEB)

    Peng, X.; Yan, J.; Zheng, L.; Wang, F. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2011-06-15

    An electrodeposited Ni-CeO{sub 2} composite was used as a ''precursor film'' for a novel CeO{sub 2}-dispersed chromium coating deposited using a traditional pack cementation method. The substrate was a carbon steel. For comparison, chromium coatings were also prepared on the untreated and pure Ni-film-treated carbon steel using the same pack cementation conditions. Oxidation in 5% O{sub 2} + 40% H{sub 2}O + N{sub 2} at 900 C showed that, compared to the CeO{sub 2}-free coating counterparts, the CeO{sub 2}-dispersed chromium coating exhibited greatly increased oxidation resistance, owing to the development of a denser and more slowly growing chromia scale. The slow growth of the scale was correlated with the CeO{sub 2} dispersion exerting the so-called ''reactive elemental effect (REE)'' on oxidation. The oxidation mechanisms in wet air of the various types of coatings were compared to those in dry air and are fully discussed in this work. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Robert D. Armstrong

    2016-05-01

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

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

    Institute of Scientific and Technical Information of China (English)

    刘斌; 陈怡; 余成志; 沈征武

    2003-01-01

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

  14. Tailoring activated carbons as catalyst for catalytic wet air oxidation of phenol

    OpenAIRE

    Baricot Mendoza, Maretva Denise

    2008-01-01

    Debido al marcado desarrollo que han tenido las actividades industriales en el mundo, el acceso al agua potable es cada vez más difícil. Durante el último siglo el consumo mundial de agua se ha incrementado 10 veces y de acuerdo con información de la Organización Mundial de la Salud 1.1 miles de millones de personas no tienen acceso a agua potable y 2.4 miles de millones no disponen de las condiciones sanitarias apropiadas. Adicionalmente, sólo 0.8% de la reserva global de agua es apta para e...

  15. Catalytic wet air oxidation of phenol in a trickle bed reactor: kinteics and reactor modelling.

    OpenAIRE

    Eftaxias, Athanasios

    2003-01-01

    El tratamiento y el reciclaje de afluentes acuosos son de máximo interés para conseguir un desarrollo sostenible de las actividades humanas. La necesidad de aprovechar en un futuro cercano las aguas residuales de procesos industriales de un modo eficaz ha reforzado la investigación sobre métodos de bajo coste para su recuperación, dado que las tecnologías existentes ya no son universalmente aplicables. La oxidación catalítica por vía húmeda (CWAO) es uno de los procesos emergentes más promete...

  16. Catalytic Wet Air Oxidation Coupled with an Aerobic Treatment to Deal with Industrial Wastewater

    OpenAIRE

    Suárez Ojeda, María Eugenia

    2006-01-01

    La reducción del agua residual y su tratamiento es uno de los retos a los que se enfrenta nuestra sociedad de consumo. Por ejemplo, en la UE se vierten 5400 toneladas al año de efluentes industriales de compuestos aromáticos, los cuales presentan efectos tóxicos y bactericidas. Hoy en día, existen varias tecnologías que han demostrado su potencial para tratar este tipo de efluentes industriales. La mayoría de ellas están basadas en la oxidación del contaminante orgánico, el cual es transforma...

  17. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

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

    2014-01-01

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

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

    OpenAIRE

    Lloyd, A.

    1982-01-01

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

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  3. Comparison of the chemical properties of wheat straw and beech fibers following alkaline wet oxidation and laccase treatments

    DEFF Research Database (Denmark)

    Schmidt, A. S.; Mallon, S.; Thomsen, Anne Belinda;

    2002-01-01

    Wheat straw (Triticum aestivum) and beech (Fagus sylvatica), were used to evaluate the effects of two pre-treatment processes (alkaline wet oxidation and enzyme treatment with laccase) on lignocellulosic materials for applications in particleboards and fiberboards. Wheat straw and beech fibers...... reacted differently in the two processes. The chemical composition changed little following enzyme treatment. After alkaline wet oxidation, fibers enriched in cellulose were obtained. With both materials, almost all hemicellulose (80%) together with a large portion of the lignin were solubilised by...... alkaline wet oxidation, but essentially all cellulose remained in the solid fraction. Following enzyme treatment most material remained as a solid. For wheat straw, reaction with acetic anhydride indicated that both treatments resulted in more hydroxyl groups being accessible for reaction. The enzyme...

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

    Science.gov (United States)

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

    2015-03-17

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

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

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  6. Preparation and characteristics of carbon-supported platinum catalyst and its application in the removal of phenolic pollutants in aqueous solution by microwave-assisted catalytic oxidation

    International Nuclear Information System (INIS)

    Granular activated carbon-supported platinum (Pt/GAC) catalysts were prepared by microwave irradiation and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Pt particles dispersing onto the surface of GAC could be penetrated by microwave and acted as 'reaction centre' in the degradations of p-nitrophenol (PNP) and pentachlorophenol (PCP) in aqueous solution by microwave-assisted catalytic oxidation. The reaction was carried out through a packed bed reactor under ambient pressure and continuous flow mode. Under the conditions of microwave power 400 W, influent flow 6.4 mL min-1 and air flow 120 mL min-1, phenolic solutions with high concentration (initial concentrations of PNP and PCP solutions were 1469 and 1454 mg L-1, respectively) were treated effectively by Pt/GAC, 86% PNP and 90% PCP were degraded and total organic carbon (TOC) removal reached 85% and 71%, respectively. Compared with GAC, loaded Pt apparently accelerated oxidative reaction so that Pt/GAC had a better degrading and mineralizing efficiencies for PNP. Hydraulic retention time was only 16 min in experiment, which was shortened greatly compared with catalytic wet air oxidation. Pyrolysis and oxidation of phenolic pollutants occurred simultaneously on the surface of Pt/GAC by microwave irradiation

  7. Development of chemical and biological processes for production of bioethanol. Optimization of the wet oxidation process and characterization of products

    International Nuclear Information System (INIS)

    The combination of the wet oxidation pretreatment process and alkaline hydrolysis was investigated in order to efficiently solubilize the hemicellulose, degrade the lignin, and open the solid crystalline cellulose structure of wheat straw lignocellulose without generating fermentation inhibitors. The effects of temperature, oxygen pressure, reaction time, and concentration of straw were evaluated. The degree of lignin degradation and hemicellulose solubilization increased with the reaction temperature and time. The optimum conditions were 15 minutes at 185 deg. C, producing 9.8 g/L hemicellulose. For quantification of the solubilized hemicellulose the best overall acid hydrolysis was obtained by treatment with 4 %w/v sulfuric acid for 10 minutes. The Aminex HPX-87H column was less sensitive towards impurities than the Aminex HPX-87P column. HPX-87H gave improved recovery and reproducibility, and was chosen for routine quantification of hydrolyzed hemicellulose sugars. The purity of the solid cellulose fraction also improved with higher temperature. The optimum condition for obtaining enzymatic convertible cellulose (90%) was 10 minutes at 170 deg. C using a high carbonate concentration. The hemicellulose yield and recovery were significantly reduced under these conditions indicating that a simultaneous optimal utilization of the hemicellulose and cellulose was difficult. The oxygen pressure and sodium carbonate concentration had little effect on the solubilization of hemicellulose, however, by combining wet oxidation with alkaline hydrolysis the formation of 2-furfural, a known microbial inhibitor, was minimal. Much more hemicellulose and lignin were solubilized from the straw by wet oxidation than by steaming(an alternative process). More cellulose was solubilized (and degraded) by steaming than by wet oxidation. Overall carbohydrates 'losses' of 20.1% for steaming and 16.2% for wet oxidation were found. More 2-furfural was formed by steaming than by wet oxidation

  8. Development of chemical and biological processes for production of bioethanol. Optimization of the wet oxidation process and characterization of products

    Energy Technology Data Exchange (ETDEWEB)

    Bjerre, A.B.; Skammelsen Schmidt, A.

    1997-02-01

    The combination of the wet oxidation pretreatment process and alkaline hydrolysis was investigated in order to efficiently solubilize the hemicellulose, degrade the lignin, and open the solid crystalline cellulose structure of wheat straw lignocellulose without generating fermentation inhibitors. The effects of temperature, oxygen pressure, reaction time, and concentration of straw were evaluated. The degree of lignin degradation and hemicellulose solubilization increased with the reaction temperature and time. The optimum conditions were 15 minutes at 185 deg. C, producing 9.8 g/L hemicellulose. For quantification of the solubilized hemicellulose the best overall acid hydrolysis was obtained by treatment with 4 %w/v sulfuric acid for 10 minutes. The Aminex HPX-87H column was less sensitive towards impurities than the Aminex HPX-87P column. HPX-87H gave improved recovery and reproducibility, and was chosen for routine quantification of hydrolyzed hemicellulose sugars. The purity of the solid cellulose fraction also improved with higher temperature. The optimum condition for obtaining enzymatic convertible cellulose (90%) was 10 minutes at 170 deg. C using a high carbonate concentration. The hemicellulose yield and recovery were significantly reduced under these conditions indicating that a simultaneous optimal utilization of the hemicellulose and cellulose was difficult. The oxygen pressure and sodium carbonate concentration had little effect on the solubilization of hemicellulose, however, by combining wet oxidation with alkaline hydrolysis the formation of 2-furfural, a known microbial inhibitor, was minimal. Much more hemicellulose and lignin were solubilized from the straw by wet oxidation than by steaming(an alternative process). More cellulose was solubilized (and degraded) by steaming than by wet oxidation. Overall carbohydrates `losses` of 20.1% for steaming and 16.2% for wet oxidation were found. More 2-furfural was formed by steaming than by wet oxidation.

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

    KAUST Repository

    Zhang, Tao

    2011-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-01-31

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

  11. Microreactor for the Catalytic Partial Oxidation of Methane

    Institute of Scientific and Technical Information of China (English)

    Widodo Wahyu Puwanto; Yuswan Muharam

    2006-01-01

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

  12. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  13. Volume reduction of lake sediment and decrease of its cesium content in decontamination process by wet oxidation method

    International Nuclear Information System (INIS)

    Wet oxidation method was applied aiming to decrease cesium contents in lake sediment. In this research, “reactive oxygen water”, that is prepared from hypochlorous acid by contact with metal ceramics, was reacted with three kinds of samples, that is, lake sediment, mixture of lake sediment and fallen leaves, and incineration ash of fallen leaves. Experimental results revealed that sample volume was reduced by means of wet oxidation of organic components in samples and that a large amount of cesium contents were transferred from sample to water phase. (author)

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

    International Nuclear Information System (INIS)

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

  15. Subcritical wet oxidation of municipal sewage sludge: comparison of batch and continuous experiments.

    Science.gov (United States)

    Lendormi, T; Prevot, C; Doppenbe, F; Foussard, J N; Debellefontaine, H

    2001-01-01

    Wet oxidation in subcritical conditions is a new alternative to usual routes for sewage sludge treatment and it complies with environmental standards. The paper presents tests carried out on a batch reactor and on a continuous pilot unit, treating municipal sewage sludge. A method is proposed that shows that the oxidation efficiency in a continuous reactor can only be easily predicted from the residence time distribution and batch tests results. Nevertheless, a partial settling of the solid residue in the continuous bubble column reactor is evident, and it increases the solid residence time and then decreases its organic content with respect to a similar batch test. In addition, these results highlight the considerable influence of temperature in the oxidation reactor and of the type of sewage sludge which is treated. At temperatures around 240 degrees C, foaming can seriously impair the operation of the continuous reactor, because of the presence of non-degraded fatty compounds and surfactants. Moreover, the COD reduction is limited to 70%. On the contrary, at 300 degrees C, COD removal efficiency greater than 80% is achieved without any catalyst additive and, in addition, only highly biodegradable compounds remain in the oxidised liquor. PMID:11695455

  16. High solid simultaneous saccharification and fermentation of wet oxidized corn stover to ethanol

    DEFF Research Database (Denmark)

    Varga, E.; Klinke, H.B.; Reczey, K.;

    2004-01-01

    In this study ethanol was produced from corn stover pretreated by alkaline and acidic wet oxidation (WO) (195 degreesC, 15 min, 12 bar oxygen) followed by nonisothermal simultaneous saccharification and fermentation (SSF). In the first step of the SSF, small amounts of cellulases were added at 50....../L) were present in the hemicellulose rich hydrolyzate at subinhibitory levels, thus no detoxification was needed prior to SSF of the whole slurry. Based on the cellulose available in the WO corn stover 83% of the theoretical ethanol yield was obtained under optimized SSF conditions. This was achieved with...... a substrate concentration of 12% dry matter (DM) acidic WO corn stover at 30 FPU/g DM (43.5 FPU/g cellulose) enzyme loading. Even with 20 and 15 FPU/g DM (corresponding to 29 and 22 FPU/g cellulose) enzyme loading, ethanol yields of 76 and 73%, respectively, were obtained. After 120 h of SSF the...

  17. Detox{sup SM} wet oxidation system studies for engineering scale up

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, D.T.; Moslander, J.E.; Zigmond, J.A. [Delphi Research, Inc., Albuquerque, NM (United States)] [and others

    1995-12-31

    Catalyzed wet oxidation utilizing iron(III) has been shown to have promise for treating many hazardous and mixed wastes. The reaction occurs at the surface of contact between an aqueous iron(III) solution and organic material. Studies with liquid- and vapor-phase organic waste surrogates have established reaction kinetics and the limits of reaction rate based on organic concentration and iron(III) diffusion. Continuing engineering studies have concentrated on reaction vessel agitator and solids feed configurations, an improved bench scale reflux condenser and reflux condenser calculations, sparging of organic compounds from the process condensate water, filtration of solids from the process solution, and flammability limits for volatile organic compounds in the headspace of the reaction vessel under the reaction conditions. Detailed engineering design and fabrication of a demonstration unit for treatment of mixed waste is in progress.

  18. Enhancing denitrification using a carbon supplement generated from the wet oxidation of waste activated sludge.

    Science.gov (United States)

    Strong, P J; McDonald, B; Gapes, D J

    2011-05-01

    This study compared the effect of four pure carbon supplements on biological denitrification to a liquor derived as a by-product from the wet oxidation (WO) of waste activated sludge. Sequencing batch reactors were used to acclimate sludge biomass, which was used in batch assays. Acetate, WO liquor and ethanol-supplementation generated the fastest denitrification rates. Acetate and WO liquor were efficiently utilised by all acclimated biomass types, while poor rates were achieved with methanol and formate. When comparing an inoculum from an ethanol-supplemented and non-supplemented wastewater treatment plant (WWTP), the ethanol-acclimated sludge obtained superior denitrification rates when supplemented with ethanol. Similarly high nitrate removal rates were achieved with both sludge types with acetate and WO liquor supplementation, indicating that WO liquors could achieve excellent rates of nitrate removal. The performance of the WO liquor was attributed to the variety of organic carbon substrates (particularly acetic acid) present within the liquor. PMID:21196117

  19. A study on wet catalysis oxidation of spent radioactive ion-exchange resin by hydrogen peroxide

    International Nuclear Information System (INIS)

    Spent radioactive ion-exchange resin (IER) is one of the main kinds of wastes produced by nuclear installations. The authors describe the study on decomposition behaviors of cationic, anionic and mixed IER in H2O2-Ni2+/Cu2+, H2O2-Mn2+/Cu2+, H2O2-Fe2+/Cu2+ and H2O2-Cu2+ systems, analyzes the effects on reaction process and consequence of many factors such as amount of H2O2, catalyst, temperature, pH-value, NaOH and so on. The relation between cementation process and the amount of decomposition residuals was studied. It provided the possible maximum COD-value under which the solidification process would not be affected. The reaction mechanism of the wet chemical oxidation of IER was discussed preliminarily

  20. Optimizing Oily Wastewater Treatment Via Wet Peroxide Oxidation Using Response Surface Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Jianzhong; Wang, Xiuqing; Wang, Xiaoyin [Wuhan Textile Univ., Wuhan (China)

    2014-02-15

    The process of petroleum involves in a large amount of oily wastewater that contains high levels of chemical oxygen demand (COD) and toxic compounds. So they must be treated before their discharge into the receptor medium. In this paper, wet peroxide oxidation (WPO) was adopted to treat the oily wastewater. Central composite design, an experimental design for response surface methodology (RSM), was used to create a set of 31 experimental runs needed for optimizing of the operating conditions. Quadratic regression models with estimated coefficients were developed to describe the COD removals. The experimental results show that WPO could effectively reduce COD by 96.8% at the optimum conditions of temperature 290 .deg. C, H{sub 2}O{sub 2} excess (HE) 0.8, the initial concentration of oily wastewater 3855 mg/L and reaction time 9 min. RSM could be effectively adopted to optimize the operating multifactors in complex WPO process.

  1. Optimizing Oily Wastewater Treatment Via Wet Peroxide Oxidation Using Response Surface Methodology

    International Nuclear Information System (INIS)

    The process of petroleum involves in a large amount of oily wastewater that contains high levels of chemical oxygen demand (COD) and toxic compounds. So they must be treated before their discharge into the receptor medium. In this paper, wet peroxide oxidation (WPO) was adopted to treat the oily wastewater. Central composite design, an experimental design for response surface methodology (RSM), was used to create a set of 31 experimental runs needed for optimizing of the operating conditions. Quadratic regression models with estimated coefficients were developed to describe the COD removals. The experimental results show that WPO could effectively reduce COD by 96.8% at the optimum conditions of temperature 290 .deg. C, H2O2 excess (HE) 0.8, the initial concentration of oily wastewater 3855 mg/L and reaction time 9 min. RSM could be effectively adopted to optimize the operating multifactors in complex WPO process

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

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, John G.

    1999-07-31

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Maciel Adeilton

    2008-01-01

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

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

    Science.gov (United States)

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

    1992-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    WANG; RongMin

    2001-01-01

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

  9. Influence of catalyst pretreatments on the catalytic oxidation of toluene over nanostructured platinum based spent catalyst.

    Science.gov (United States)

    Shim, Wang-Geun; Lee, Jae-Wook; Kim, Sang-Chai

    2007-11-01

    In this study, we regenerated a nano-structured platinum based spent catalyst by applying thermal gas and acid pretreatment and examined the influence of treatment on the catalytic oxidation of toluene. The spent catalysts were pretreated with air, hydrogen and six different acid aqueous solutions (HCl, H2SO4, HNO3, H3PO4, CH3COOH and C2H2O4). The physicochemical properties of the parent and its modified catalysts were characterized by XRD, BET, TEM, and ICP. The results of light-off curves showed that air and hydrogen treated catalysts were more active than the parent catalyst. In addition, the catalytic activities of toluene oxidation for acid aqueous treated samples were identical with the order of Pt/Al ratio. PMID:18047055

  10. Catalytic Oxidation of Phenol over Zeolite Based Cu/Y-5 Catalyst: Part 1: Catalyst Preparation and Characterization

    Directory of Open Access Journals (Sweden)

    K. Maduna Valkaj

    2015-01-01

    Full Text Available The necessity to remove organic pollutants from the industrial wastewater streams has forced the development of new technologies that can produce better results in terms of pollutant removal and process efficiency in combination with low investment and operating costs. One of the new emerging processes with a potential to fulfil these demands is catalytic wet peroxide oxidation, commonly known as the CWPO process. The oxidative effect of the hydrogen peroxide is intensified by the addition of a heterogeneous catalyst that can reduce the operating conditions to atmospheric pressure and temperatures below 383 K. Zeolites, among others, are especially appealing as catalysts for selective oxidation processes due to their unique characteristics such as shape selectivity, thermal and chemical stability, and benign effect on nature and the living world. In this work, catalytic activity, selectivity and stability of Cu/Y-5 zeolite in phenol oxidation with hydrogen peroxide was examined. Catalyst samples were prepared by ion exchange method of the protonic form of commercial zeolite. The catalysts were characterized with powder X-ray diffraction (XRD, scanning electron microscopy (SEM, and AAS elemental analysis, while the adsorption techniques were used for the measurement of the specific surface area. The catalytic tests were carried out in a stainless steel Parr reactor in batch operation mode at the atmospheric pressure and in the temperature range from 323 to 353 K. The catalyst was prepared in powdered form and the mass fraction of the active metal component on the zeolite was 3.46 %. The initial concentration of phenol solution was equal to 0.01 mol dm−3 and the concentration of hydrogen peroxide ranged from 0.01 to 0.10 mol dm−3. The obtained experimental data was tested to a proposed kinetic model for phenol oxidation r = k1 cF cVP and hydrogen peroxide decomposition rHP = k2 cHP. The kinetic parameters were estimated using the Nelder

  11. Optical and electro-catalytic studies of nanostructured thulium oxide for vitamin C detection

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jay [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Srivastava, Manish [Department of Physics, Dehradun Institute of Technology (DIT), School of Engineering, Greater Noida 201308 (India); Roychoudhury, Appan [Department of Biotechnology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110 042 (India); Lee, Dong Won [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Lee, Seung Hee, E-mail: lsh1@jbnu.ac.kr [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Malhotra, B.D., E-mail: bansi.malhotra@gmail.com [Department of Biotechnology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110 042 (India); Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, Material Physics and Engineering Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110 012 (India); Center for NanoBioengineering and Spintronics, Chungnam National University, 220 Gung-Dong, Yuseong-Gu, Daejeon 305-764 (Korea, Republic of)

    2013-11-25

    Highlights: •Nanostructured thulium oxide has been prepared using the hydrothermal process. •Thulium oxide exhibits excellent electrochemical response towards ascorbic acid. •Thulium oxide is interesting electro-optical material. •Rare earth metal oxide offers potential application biosensing and optoelectronics. -- Abstract: In this report, the nanostructured thulium oxide (Tm{sub 2}O{sub 3}) has been prepared using the hydrothermal process without using any template and further heat treatment. The crystalline structure and morphology of prepared sample have been determined by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopic techniques. The optical properties of prepared sample have been examined by ultra-violet (UV–Vis), photoluminescence (PL), Raman and X-ray photoelectron spectroscopy (XPS) studies. Furthermore, Tm{sub 2}O{sub 3} nanoparticles have been electrophoretically deposited (EPD) onto indium–tin–oxide (ITO) glass substrate and utilized for electro-oxidation of ascorbic acid (AA). The electro-catalytic behavior of Tm{sub 2}O{sub 3}/ITO and bare ITO electrodes for AA electro-oxidation has been studied by cyclic voltammetry. Catalytic oxidation peak current shows a linear dependence on the AA concentration and a linear calibration curve is obtained in the concentration range of 0.2–8 mM of AA. The obtained results indicate that the nanostructured Tm{sub 2}O{sub 3} based electrode offers an efficient strategy and a new promising platform for application of the rare earth metal oxide material in electrochemistry and bioelectronics.

  12. Catalytic production of carbon nanotubes over first row transition metal oxides supported on montmorillonite

    International Nuclear Information System (INIS)

    Clay-carbon nanotube composites were prepared by employing the catalytic chemical vapor deposition method (CCVD) over different transition metal oxides supported on montmorillonite. Various analytical techniques including SEM, TEM, XRD and DTA/TGA were used for the characterization of the final composite materials. The morphology, quality and structure of the produced nanotubes is shown to be dependent on the type of transition metals

  13. Investigation of catalyst and solvent systems for the catalytic oxidation of Kraft lignin

    OpenAIRE

    Mora Mir, Joan

    2010-01-01

    Lignin is one of the main constituents of wood together with cellulose and hemicellulose and can be used as a renewable feedstock for the production of chemicals. Lignin is an amorphous polymer which is separated from cellulose during the pulping processes in the paper industry. The Kraft process is the most extended pulping process and the so called Kraft lignin is one of the most promising sources for the obtaining of value-added products from its degradation. The catalytic oxidation of ...

  14. Visualizing a Catalyst at Work during the Ignition of the Catalytic Partial Oxidation of Methane

    DEFF Research Database (Denmark)

    Kimmerle, Bertram; Grunwaldt, Jan-Dierk; Baiker, Alfons;

    2009-01-01

    We present a spatiotemporal operando X-ray absorption study of a highly dynamic process, the ignition of the noble metal catalyzed partial oxidation of methane. Evolvement and propagation of the platinum component's structural changes are investigated with a high-speed X-ray camera, which in comb...... combination with temperature profiling by IR-thermography and catalytic activity measurements by online mass spectrometry gives insight into the first stages of the ignition of the reaction toward hydrogen and carbon monoxide....

  15. The catalytic oxidation of biomass to new materials focusing on starch, cellulose and lignin

    OpenAIRE

    Collinson, S. R.; Thielemans, W.

    2010-01-01

    Biomass is a renewable class of materials of growing interest amongst researchers aiming to achieve global sustainability. This review focuses on the homogeneous catalysis of the oxidation of biomass, in particular starch, cellulose and lignin. Often such catalytic reactions lead to depolymerisation of the material as happens in Nature with for example brown rot fungi. This depolymerisation can be desirable or not, and control in industrial applications is thus important to obtain the desired...

  16. Thermodynamic Study on the Catalytic Partial Oxidation of Methane to Syngas

    Institute of Scientific and Technical Information of China (English)

    XUJian; WEIWeisheng; 等

    2002-01-01

    The catalytic partial oxidation of methane to syngas (CO+H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature,pressure,CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.

  17. Catalytic Decomposition of Nitrous Oxide over Calcined Hydrotalcite-like Compounds

    Czech Academy of Sciences Publication Activity Database

    Obalová, L.; Kovanda, F.; Jirátová, Květa; Chmielová, M.; Wichterle, K.; Dorničák, V.

    Vol. 1. Prague : Process Engineering Publisher, 2002, s. 356. ISBN 80-86059-33-2. [International Congress of Chemical and Process Engineering CHISA 2002 /15./. Prague (CZ), 25.08.2002-29.08.2002] R&D Projects: GA ČR GA106/02/0523 Institutional research plan: CEZ:AV0Z4072921 Keywords : nitrous oxide * catalytic decomposition * hydrotalcite Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  18. Oxidation of hydrogen halides to elemental halogens with catalytic molten salt mixtures

    Science.gov (United States)

    Rohrmann, Charles A.

    1978-01-01

    A process for oxidizing hydrogen halides by means of a catalytically active molten salt is disclosed. The subject hydrogen halide is contacted with a molten salt containing an oxygen compound of vanadium and alkali metal sulfates and pyrosulfates to produce an effluent gas stream rich in the elemental halogen. The reduced vanadium which remains after this contacting is regenerated to the active higher valence state by contacting the spent molten salt with a stream of oxygen-bearing gas.

  19. The effect of noble metals on catalytic methanation reaction over supported Mn/Ni oxide based catalysts

    Directory of Open Access Journals (Sweden)

    Wan Azelee Wan Abu Bakar

    2015-09-01

    Full Text Available Carbon dioxide (CO2 in sour natural gas can be removed using green technology via catalytic methanation reaction by converting CO2 to methane (CH4 gas. Using waste to wealth concept, production of CH4 would increase as well as creating environmental friendly approach for the purification of natural gas. In this research, a series of alumina supported manganese–nickel oxide based catalysts doped with noble metals such as ruthenium and palladium were prepared by wetness impregnation method. The prepared catalysts were run catalytic screening process using in-house built micro reactor coupled with Fourier Transform Infra Red (FTIR spectroscopy to study the percentage CO2 conversion and CH4 formation analyzed by GC. Ru/Mn/Ni(5:35:60/Al2O3 calcined at 1000 °C was found to be the potential catalyst which gave 99.74% of CO2 conversion and 72.36% of CH4 formation at 400 °C reaction temperature. XRD diffractogram illustrated that the supported catalyst was in polycrystalline with some amorphous state at 1000 °C calcination temperature with the presence of NiO as active site. According to FESEM micrographs, both fresh and used catalysts displayed spherical shape with small particle sizes in agglomerated and aggregated mixture. Nitrogen Adsorption analysis revealed that both catalysts were in mesoporous structures with BET surface area in the range of 46–60 m2/g. All the impurities have been removed at 1000 °C calcination temperature as presented by FTIR, TGA–DTA and EDX data.

  20. Catalytic oxidation of hydrocarbons by dinuclear iron complexes

    International Nuclear Information System (INIS)

    Our efforts during the past eight months were directed towards characterizing synthetic complexes that model the electronic and reactivity properties of the active site of methane monooxygenase (MMO), a metalloenzyme found in methanotrophic bacteria responsible for the biological oxidation of methane to methanol. We have investigated the structural/electronic and reactivity properties of a series of dinuclear model complexes that can function as oxygen atom transfer catalysts. In particular, our studies focused on [Fe2+2(H2Hbab)2(N-MeIM)], its DMF solvated form, [Fe2+2(H2Hbab)2(DMF)2(N-MeIM)], and the mixed valent species [[Fe2+2(H2Hbab)2(DMF)4]+, (H4Hbab = 1,2-bis(2-hydroxybenzamido) benzene). We have also examined [Fe3+2(H2Hbab)2(DMF)4]2, [Fe3+2(H2Hbab)2(OMe)2], and μ-oxo[Fe3+2(H2Hbab)2(DMF)2], which are unable to act as oxygen atom transfer catalysts

  1. Alkali Metals Promoted Co-Mn-Al Mixed Oxide for N2O Catalytic Decomposition

    Czech Academy of Sciences Publication Activity Database

    Karásková, K.; Kulová, T.; Obalová, L.; Jirátová, Květa; Kovanda, F.

    Bratislava : Slovak Society of Chemical Engineering, 2011 - (Markoš, J.), s. 251 ISBN 978-80-227-3503-2. [International Conference of Slovak Society of Chemical Engineering /38./. Tatranské Matliare (SK), 23.05.2011-27.05.2011] R&D Projects: GA ČR GA106/09/1664 Grant ostatní: GA MŠk ED2.1.00/03.0100 Institutional research plan: CEZ:AV0Z40720504 Keywords : nitrous oxide * catalytic decomposition * mixed oxide catalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  2. Exoemission and catalytic activity of oxides of the perovskite and spinel structures in the processes of CO and hydrocarbons oxidation

    International Nuclear Information System (INIS)

    Low-temperature (20-400 deg C) exoemission of negative charges from complex oxides featuring perovskite structure AMO3 (A = La; M = Co, Mn, Ni) and spinel structure A'M'2O4 (A' = Cu; M' = Fe, Co, Cr) was studied using the Geiger gas-flow counter. The experiments were carried out under conditions of thermally induced emission, photo- and thermally induced emission during irradiation of samples by UV light with the wavelength of 313 nm, as well as thermally induced emission under effect of β-radiation of 90Y-90Sr with dose of 0.23 Gy. Correlation between emissivity of the oxides and catalytic activity was established. The role of weakly bound oxygen and variable valency ions in exoemission and oxidizing catalysis processes involving the complex oxides was discussed

  3. Catalytic combustion of methane by perovskite-type oxide nanoparticles as pollution prevention strategy

    Science.gov (United States)

    Zaza, F.; Luisetto, I.; Serra, E.; Tuti, S.; Pasquali, M.

    2016-06-01

    The transition from the existing brown economy towards the desired green economy drives the research efforts to the development of advanced technologies promoting the efficient utilization of energy sources. Catalysis science offers to combustion technology significant opportunity to increase the fuel efficiency by lowering the internal temperature gradients and reduce the environmental impact by lowering local peak temperature and, consequently, thermodynamically inhibiting the nitrogen oxides formation. Alternative catalytic materials are transition metals oxide, including complex oxides with perovskite crystalline structure. The aim of this work is to synthetize lanthanum ferrite perovskites with lanthanum ions partially substituted by strontium ions in order to study the substitution effects on structural properties and redox activity of the original oxide. Lanthanum ferrite oxides partially substituted with different Strontium amount were synthesized by solution combustion method. The perovskite nanopowders obtained were characterized by XRD, SEM, TPR analyses for defining crystalline structure, morphology and redox properties. Finally, the catalytic activity for methane combustion was tested. The most performing catalysts was La0.6Sr0.4FeO3 having the highest oxygen vacancy concentration as revealed by TPR analysis.

  4. Analytical aspects of the remediation of soil by wet oxidation - Characterisation of tar contaminants and their degradation products

    DEFF Research Database (Denmark)

    Thomsen, A.B.; Nielsen, T.; Plöger, A.;

    1999-01-01

    Wet oxidation of tar compounds gives rise to a wide range of products. Due to the incorporation of oxygen, these products become increasingly more water soluble and the analytical strategy has to take into account the different physical/chemicalproperties of the compounds. An interplay between gas...

  5. Potential inhibitors from wet oxidation of wheat straw and their effect on growth and ethanol production by Thermoanaerobacter mathranii

    DEFF Research Database (Denmark)

    Klinke, Helene Bendstrup; Thomsen, A.B.; Ahring, Birgitte Kiær

    2001-01-01

    Alkaline wet oxidation (WO) (using water, 6.5 g/l sodium carbonate, and 12 bar oxygen at 195 degreesC) was used for pre-treating wheat straw (60 g/l), resulting in a hemicellulose-rich hydrolysate and a cellulose-rich solid fraction. The hydrolysate consisted of soluble hemicellulose (9 g/l), ali...

  6. Wet oxidation treatment of organic household waste enriched with wheat straw for simultaneous saccharification and fermentation into ethanol

    DEFF Research Database (Denmark)

    Lissens, G.; Klinke, H.B.; Verstraete, W.;

    2004-01-01

    Organic municipal solid waste enriched with wheat straw was subjected to wet-oxidation as a pre-treatment for subsequent enzymatic conversion and fermentation into bio-ethanol. The effect of tempera (185-195degrees C), oxygen pressure (3-12) and sodium carbonate (0-2 g l(-1)) addition on enzymati...

  7. Wet oxidation pre-treatment of woody yard waste: Parameter optimization and enzymatic digestibility for ethanol production

    DEFF Research Database (Denmark)

    Lissens, G.; Klinke, H.B.; Verstraete, W.;

    2004-01-01

    Woody yard waste with high lignin content (22% of dry matter (DM)) was subjected to wet oxidation pre-treatment for subsequent enzymatic conversion and fermentation. The effects of temperature (185-200 degreesC), oxygen pressure (3-12 bar) and addition of sodium carbonate (0-3.3 g per 100 g DM bi...

  8. Wet oxidation of domestic sludge and process integration: the Mineralis process.

    Science.gov (United States)

    Lendormi, T; Prévot, C; Doppenberg, F; Spérandio, M; Debellefontaine, H

    2001-01-01

    Wet oxidation (WO) in subcritical conditions is a new alternative to usual routes for sewage sludge treatment that complies with environmental standards. This paper presents tests carried out using a batch reactor and continuous pilot and industrial units, treating municipal sewage sludge. The main products after oxidation are CO2, water, VFA and ammonia. The results highlight the considerable influence of the treatment temperature and of the type of sewage sludge which is treated. At temperatures around 240 degrees C, VFA fraction present in WO supernatant is limited to 50% because of the presence of non-degraded fatty compounds and surfactants. Moreover, the COD reduction is limited to 70%. On the contrary, at 300 degrees C, COD removal efficiencies greater than 80% are achieved without any catalyst addition and, in addition, only highly biodegradable compounds remain in the oxidised liquor. In order to treat the residual ammonia nitrogen by biological processes, it is therefore necessary to obtain a VFA fraction as high as possible for achieving denitrification and then to operate the WO process at high temperature and without catalyst addition. PMID:11794648

  9. Wet oxidation of spent TBP/OK and interphase crud by H2O2

    International Nuclear Information System (INIS)

    Wet oxidation of simulated organic filth by hydrogen peroxide catalysed by Fe2+ is investigated. The factors influencing reactions such as H2O2 dosage, catalyst, pH-value and so on are studied. With regard to reagent addition manner, intermittent addition is advised for the utilization of H2O2, pH value of the system is 1-2. To assure fast startup and going along placidly of the reaction, a third of the catalyst is mixed with the filth before the oxidation, the other two thirds are added in the reacting solution continuously during the reaction process and finished the addition half an hour before the end of the reaction. TBP/OK, HDBP/OK and interphase crud can be decomposed effectively by H2O2. Finally, trivariant normal experiments are employed for determination of the optimal conditions. When the dosage of cruds is 2.00 g, the optimal conditions are pH=1, 10 mL H2O2, 10 mL 0.1 mol/L Fe2+. The element analysis and infrared spectroscopic analysis shows that the main component of the residual from the reaction is phosphate. (authors)

  10. Comparison study of Cu-Fe-Ti and Co-Fe-Ti oxide catalysts for selective catalytic reduction of NO with NH3 at low temperature.

    Science.gov (United States)

    Zhu, Lin; Zhong, Zhaoping; Yang, Han; Wang, Chunhua

    2016-09-15

    In this paper, a series of Cu-Fe-Ti and Co-Fe-Ti oxide catalysts were prepared by sol gel method. Cu-Fe-Ti and Co-Fe-Ti oxide catalysts showed the moderate catalytic activity for selective catalytic reduction (SCR) of NO with NH3 at low temperature. The catalysts with the molar ratio as 4:1:10 (M:Fe:Ti) were selected as the representatives for comparison of reaction properties and H2O resistance, which were denoted as Cu-Fe/TiO2 and Co-Fe/TiO2 respectively. The characterization results manifested Co-Fe/TiO2 owned more adsorption capacity of the reactants and Cu-Fe/TiO2 had better redox ability. The in situ DRIFTS experiments indicated that adsorbed NH3 species and nitrate species both exhibited reaction activity for Co-Fe/TiO2, while nitric oxide was only be reduced by adsorbed NH3 species through Eley-Rideal mechanism for Cu-Fe/TiO2 at 150°C. Co-Fe/TiO2 exhibited the better resistance to H2O and its temperature window shifted towards the higher temperature in presence of 10vol% H2O, while the SCR activity of Cu-Fe/TiO2 was inhibited significantly in the whole temperature range investigated. The suppression of adsorption and activation for NH3 and NOx might be the reasons for the reversible inactivation, which was confirmed by the inhibitation of catalytic activities for separation NH3 and NO oxidation under the wet condition. We speculated that different thermal stability of adsorbed species and redox capacity of catalysts leaded to the different SCR behavior in absence and presence of H2O. PMID:27280535

  11. Catalytic performance of Fe-ZSM-5 catalysts for selective catalytic reduction of nitric oxide by ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Long, R.Q.; Yang, R.T.

    1999-12-10

    A series of Fe-exchanged molecular sieves were studied as catalysts for the selective catalytic reduction (SCR) of NO with ammonia. It was found that Fe-ZSM-5 and Fe-mordenite catalysts were highly active for the SCR reaction. Nearly 100% NO conversions were obtained at 400--500 C under conditions with a high space velocity (GHSV = 4.6 x 10{sup 5} 1/h). However, Fe-Y and Fe-MCM-41 with larger pore sizes showed lower activities for this reaction. F or Fe-ZSM-5 catalysts, the SCR activity decreased with increasing Si/Al ratio in the zeolites. As the Fe-exchange level in the Fe-ZSM-5 catalysts was increased from 58 to 252%, NO conversion increased at lower temperatures (e.g., 300 C), but decreased at high temperatures (e.g., 600 C). Compared with the commercial vanadia catalyst, based on the first-order rate constants, the Fe-ZSM-5 catalyst was five times more active at 400 C and seven times more active at 450 C. It also functioned in a broader temperature window, produced only N{sub 2} (rather than N{sub 2}O) and H{sub 2}O, and showed a substantially lower activity for oxidation of SO{sub 2} to SO{sub 3}.

  12. Heterogeneous catalytic ozonation of ciprofloxacin in water with carbon nanotube supported manganese oxides as catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sui, Minghao, E-mail: suiminghao.sui@gmail.com [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Xing, Sichu; Sheng, Li; Huang, Shuhang; Guo, Hongguang [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Ciprofloxacin in water was degraded by heterogeneous catalytic ozonation. Black-Right-Pointing-Pointer MnOx were supported on MWCNTs to serve as catalyst for ozonation. Black-Right-Pointing-Pointer MnOx/MWCNT exhibited highly catalytic activity on ozonation of ciprofloxacin in water. Black-Right-Pointing-Pointer MnOx/MWCNT resulted in effective antibacterial activity inhibition on ciprofloxacin. Black-Right-Pointing-Pointer MnOx/MWCNT promoted the generation of hydroxyl radicals. - Abstract: Carbon nanotube-supported manganese oxides (MnOx/MWCNT) were used as catalysts to assist ozone in degrading ciprofloxacin in water. Manganese oxides were successfully loaded on multi-walled carbon nanotube surfaces by simply impregnating the carbon nanotube with permanganate solution. The catalytic activities of MnOx/MWCNT in ciprofloxacin ozonation, including degradation, mineralization effectiveness, and antibacterial activity change, were investigated. The presence of MnOx/MWCNT significantly elevated the degradation and mineralization efficiency of ozone on ciprofloxacin. The microbiological assay with a reference Escherichia coli strain indicated that ozonation with MnOx/MWCNT results in more effective antibacterial activity inhibition of ciprofloxacin than that in ozonation alone. The effects of catalyst dose, initial ciprofloxacin concentration, and initial pH conditions on ciprofloxacin ozonation with MnOx/MWCNT were surveyed. Electron spin resonance trapping was applied to assess the role of MnOx/MWCNT in generating hydroxyl radicals (HO{center_dot}) during ozonation. Stronger 5,5-dimethyl-1-pyrroline-N-oxide-OH signals were observed in the ozonation with MnOx/MWCNT compared with those in ozonation alone, indicating that MnOx/MWCNT promoted the generation of hydroxyl radicals. The degradation of ciprofloxacin was studied in drinking water and wastewater process samples to gauge the potential effects of water background matrix on

  13. Enhanced catalytic oxidation ability of ternary layered double hydroxides for organic pollutants degradation.

    Science.gov (United States)

    Fahel, Jean; Kim, Sanghoon; Durand, Pierrick; André, Erwan; Carteret, Cédric

    2016-05-10

    Co(2+) and Cu(2+) substituted MgAl layered double hydroxides with an M(2+)/M(3+) atomic ratio of 2.0 were synthesized by a co-precipitation method and fully characterized using various techniques including powder X-ray diffraction, ICP-AES analysis, FT-IR, DR UV-Vis spectroscopy, N2 adsorption-desorption and transmission electron microscopy. The materials revealed a good crystallinity with no phase impurity and successful substitution of cobalt and copper ions in the framework of binary LDH with the target ratio of metals in the sheet. The adsorption characteristics (kinetic and isotherm) and the catalytic oxidation of organic pollutants, methylene blue (cationic dye) and orange II (anionic) were carried out to investigate a potential use of LDH materials as catalysts. In particular, Co3Cu1Al2 LDH exhibited an excellent catalytic activity towards catalytic dye degradation, especially for orange II with good stability and reusability over several times. Furthermore, this LDH material showed good catalytic performance for several chlorophenol compounds, suggesting its practical application in wastewater treatment. Therefore, layered double hydroxides substituted with Co(2+) and Cu(2+) could be promising candidates in various applications, such as the abatement of organic pollutants. PMID:27097543

  14. Intrinsic catalytic properties of extruded clay honeycomb monolith toward complete oxidation of air pollutants.

    Science.gov (United States)

    Assebban, Mhamed; El Kasmi, Achraf; Harti, Sanae; Chafik, Tarik

    2015-12-30

    The present work highlights the intrinsic catalytic properties of extruded clay honeycomb monolith toward complete oxidation of various air pollutants namely CO, methane, propane, acetylene, propene, n-butene, methanol, ethanol, n-propanol, n-butanol, acetone, dimethyl ether, benzene, toluene, o-xylene, monochlorobenzene and 1,2-dichlorobenzene. Total catalytic conversion was achieved for all tested compounds with different behaviors depending on pollutants' structural and chemical nature. The comparison of T50 values obtained from light-off curves allowed the establishment of the following reactivity sequence: ketone>alcohol>ether>CO>alkyne>aromatic>alkene>chlorinated aromatic>alkane. The intrinsic catalytic performances of the natural clay was ascribed to the implication of a quite complex mixture constituted by OH groups (Brønsted acids) and coordinately-unsaturated cations, such as Al(3+), Fe(3+) and Fe(2+) (Lewis acids). Hence, the combination of the clay's intrinsic catalytic performances and easier extrudability suggests a promissory potential for application in air pollution control. PMID:26259164

  15. Catalytic oxidation of N-methyldiphenylamine-4-sulfonic acid in weakly acid solutions: a study by radiospectroscopic methods

    International Nuclear Information System (INIS)

    The mechanism of the catalytic oxidation of N-methyldiphenylamine-4-sulfonic acid (MDPASA) in weakly acid (10-3 M H2SO4) solutions is studied by EPR and 1H NMR spectroscopy. It is shown that the oxidation of the reagent with potassium periodate in the presence of ruthenium(4) proceeds through the radical mechanism that includes alternate steps of the oxidation and reduction of the catalyst. The suggested mechanism of the catalytic oxidation of MDPASA gave theoretical grounds to the conditions for the determination of ruthenium by kinetic methods that were selected previously in the basis of experimental data

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

    Science.gov (United States)

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

    2014-04-28

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

  17. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    Science.gov (United States)

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-09-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested.

  18. Reduced graphene oxide supported platinum nanocubes composites: one-pot hydrothermal synthesis and enhanced catalytic activity

    International Nuclear Information System (INIS)

    Reduced graphene oxide (rGO) supported platinum nanocubes (Pt-NCs) composites (Pt-NCs/rGO) were synthesized successfully by a water-based co-chemical reduction method, in which polyallylamine hydrochloride acted as a multi-functional molecule for the functionalization of graphene oxide, anchorage of PtII precursor, and control of Pt crystal facets. The morphology, structure, composition, and catalytic property of Pt-NCs/rGO composites were characterized in detail by various spectroscopic techniques. Transmission electron microscopy images showed well-defined Pt-NCs with an average size of 9 nm uniformly distributed on the rGO surface. The as-prepared Pt-NCs/rGO composites had excellent colloidal stability in the aqueous solution, and exhibited superior catalytic activity towards the hydrogenation reduction of nitro groups compared to commercial Pt black. The improved catalytic activity originated from the abundant exposed Pt{100} facets of Pt-NCs, excellent dispersion of Pt-NCs on the rGO surface, and synergistic effect between Pt-NCs and rGO. (paper)

  19. Magnetic bimetallic nanoparticles supported reduced graphene oxide nanocomposite: Fabrication, characterization and catalytic capability

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei; Wu, Tao; Xu, Xiaoyang; Xia, Fengling; Na, Heya [School of Science, Tianjin University, Tianjin 300072 (China); Liu, Yu, E-mail: liuyuls@163.com [School of Science, Tianjin University, Tianjin 300072 (China); Qiu, Haixia [School of Science, Tianjin University, Tianjin 300072 (China); Wang, Wei [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Gao, Jianping, E-mail: jianpinggao2012@126.com [School of Science, Tianjin University, Tianjin 300072 (China)

    2015-04-15

    Highlights: • Ni and Ag nanoparticles loaded on RGO (Ni–Ag@RGO) were fabricated in a one-pot reaction. • The Ni–Ag@RGO were excellent catalysts for the reduction of 4-nitrophenol. • The Ni–Ag@RGO showed superior catalytic activity for photodegradation of methyl orange. • The Ni–Ag@RGO exhibit good reusability in a magnetic field. - Abstract: A facile method for preparing Ni–Ag bimetallic nanoparticles supported on reduced graphene oxide (Ni–Ag@RGO hybrid) has been established. Hydrazine hydrate was used as the reducing agent to reduce the graphene oxide, Ni{sup 2+} and Ag{sup +} to form Ni–Ag@RGO hybrid. The prepared hybrid was further characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. Interestingly, the prepared material shown good magnetic properties, which were determined by vibrating sample magnetometer. In addition, the Ni–Ag@RGO hybrid exhibited excellent catalytic activity for the reduction of 4-nitrophenol and the photodegradation of methyl orange. The catalytic process was monitored by determining the change in the concentration of the reactants with time using ultraviolet–visible absorption spectroscopy. After completion of the reaction, the catalyst can be separated from the reaction system simply under a magnet field and shows good recyclability.

  20. Oxidative catalytic evolution of redox- and spin-states of a Fe-phthalocyanine studied by EPR

    Science.gov (United States)

    Bletsa, Eleni; Solakidou, Maria; Louloudi, Maria; Deligiannakis, Yiannis

    2016-04-01

    The catalytic-oxidative evolution of the redox/spin states of a Fe-phthalocyanine (Fe-Pc) catalyst was studied by electron paramagnetic resonance spectroscopy. Under oxidative catalytic conditions, Fe-Pc may evolve via multiple redox/spin conformations. Axial ligation of imidazole, O2 or t-Bu-OOH as oxidant, results in a complex multipath redox/spin landscape that was determined in detail herein. The high-spin conformations of Fe-Pc/imidazole evolve more slowly than the low-spin conformations. Catalytically active vs. inactive conformations were distinguished. A unified physicochemical catalytic reaction mechanism is discussed herein based on the distinct role of the various structural, spin and redox forms.

  1. Full scale calcium bromide injection with subsequent mercury oxidation and removal within wet flue gas desulphurization system: Experience at a 700 MW coal-fired power facility

    Science.gov (United States)

    Berry, Mark Simpson

    The Environmental Protection Agency promulgated the Mercury and Air Toxics Standards rule, which requires that existing power plants reduce mercury emissions to meet an emission rate of 1.2 lb/TBtu on a 30-day rolling average and that new plants meet a 0.0002 lb/GWHr emission rate. This translates to mercury removals greater than 90% for existing units and greater than 99% for new units. Current state-of-the-art technology for the control of mercury emissions uses activated carbon injected upstream of a fabric filter, a costly proposition. For example, a fabric filter, if not already available, would require a 200M capital investment for a 700 MW size unit. A lower-cost option involves the injection of activated carbon into an existing cold-side electrostatic precipitator. Both options would incur the cost of activated carbon, upwards of 3M per year. The combination of selective catalytic reduction (SCR) reactors and wet flue gas desulphurization (wet FGD) systems have demonstrated the ability to substantially reduce mercury emissions, especially at units that burn coals containing sufficient halogens. Halogens are necessary for transforming elemental mercury to oxidized mercury, which is water-soluble. Plants burning halogen-deficient coals such as Power River Basin (PRB) coals currently have no alternative but to install activated carbon-based approaches to control mercury emissions. This research consisted of investigating calcium bromide addition onto PRB coal as a method of increasing flue gas halogen concentration. The treated coal was combusted in a 700 MW boiler and the subsequent treated flue gas was introduced into a wet FGD. Short-term parametric and an 83-day longer-term tests were completed to determine the ability of calcium bromine to oxidize mercury and to study the removal of the mercury in a wet FGD. The research goal was to show that calcium bromine addition to PRB coal was a viable approach for meeting the Mercury and Air Toxics Standards rule

  2. Highly n-Type Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

    KAUST Repository

    Baker, L. Robert

    2011-08-18

    The role of the oxide-metal interface in determining the activity and selectivity of chemical reactions catalyzed by metal particles on an oxide support is an important topic in science and industry. A proposed mechanism for this strong metal-support interaction is electronic activation of surface adsorbates by charge carriers. Motivated by the goal of using electronic activation to drive nonthermal chemistry, we investigated the ability of the oxide support to mediate charge transfer. We report an approximately 2-fold increase in the turnover rate of catalytic carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titanium dioxide (TiO2) when the TiO2 is made highly n-type by fluorine (F) doping. However, for nonstoichiometric titanium oxide (TiOX<2) the effect of F on the turnover rate is negligible. Studies of the titanium oxide electronic structure show that the energy of free electrons in the oxide determines the rate of reaction. These results suggest that highly n-type TiO2 electronically activates adsorbed oxygen (O) by electron spillover to form an active O- intermediate. © 2011 American Chemical Society.

  3. Communication: Towards catalytic nitric oxide reduction via oligomerization on boron doped graphene

    Science.gov (United States)

    Cantatore, Valentina; Panas, Itai

    2016-04-01

    We use density functional theory to describe a novel way for metal free catalytic reduction of nitric oxide NO utilizing boron doped graphene. The present study is based on the observation that boron doped graphene and O—N=N—O- act as Lewis acid-base pair allowing the graphene surface to act as a catalyst. The process implies electron assisted N=N bond formation prior to N—O dissociation. Two N2 + O2 product channels, one of which favoring N2O formation, are envisaged as outcome of the catalytic process. Besides, we show also that the N2 + O2 formation pathways are contrasted by a side reaction that brings to N3O3- formation and decomposition into N2O + NO2-.

  4. Selective catalytic reduction of nitrogen oxides from industrial gases by hydrogen or methane

    International Nuclear Information System (INIS)

    This work deals with the selective catalytic reduction of nitrogen oxides (NOx), contained in the effluents of industrial plants, by hydrogen or methane. The aim is to replace ammonia, used as reducing agent, in the conventional process. The use of others reducing agents such as hydrogen or methane is interesting for different reasons: practical, economical and ecological. The catalyst has to convert selectively NO into N2, in presence of an excess of oxygen, steam and sulfur dioxide. The developed catalyst is constituted by a support such as perovskites, particularly LaCoO3, on which are dispersed noble metals (palladium, platinum). The interaction between the noble metal and the support, generated during the activation of the catalyst, allows to minimize the water and sulfur dioxide inhibitor phenomena on the catalytic performances, particularly in the reduction of NO by hydrogen. (O.M.)

  5. Catalytic effects of trace ruthenium on oxidation of dimethyl yellow with bromate and its application

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-rong; WANG Qun; ZHANG Shu-yuan

    2008-01-01

    A spectrophotometric method for the determination of ruthenium(Ⅲ) is described, based on its catalytic effect on the oxidation reaction of dimethyl yellow (DMY) with potassium bromate in an acid solution medium and in the presence of an OP emulsifier (p-iso-octyl phenoxy polyethoxy ethanol) at 100 ℃. This reaction was followed spectrophotometrically by measuring the decrease in the absorbance at 530 nm of the catalytic reaction of DMY. The calibration curve for the recommended method was linear in the concentration range over 0.0-1.0 μg/Land the detection limit of the method for Ru(Ⅲ) was 0.01 μg/L. The method is highly sensitive, selective and very stable and has been successfully applied for the determination of trace amounts of ruthenium in some ores and metallurgy products with the relative standard deviations (RSD) over 1.6%-2.8% and a recovery over 98.7%-104.0%.

  6. Yield optimization in a cycled trickle-bed reactor: ethanol catalytic oxidation as a case study

    Energy Technology Data Exchange (ETDEWEB)

    Ayude, A.; Haure, P. [INTEMA, CONICET, Mar del Plata (Argentina); Cassanello, M. [Universidad de Buenos Aires, PINMATE, Departamento de Industrias, FCEyN, Buenos Aires (Argentina); Martinez, O. [Departamento de Ingenieria Quimica, FI-UNLP-CINDECA, La Plata (Argentina)

    2012-05-15

    The effect of slow ON-OFF liquid flow modulation on the yield of consecutive reactions is investigated for oxidation of aqueous ethanol solutions using a 0.5 % Pd/Al{sub 2}O{sub 3} commercial catalyst in a laboratory trickle-bed reactor. Experiments with modulated liquid flow rate (MLFR) were performed under the same hydrodynamic conditions (degree of wetting, liquid holdup) as experiments with constant liquid flow rate (CLFR). Thus, the impact of the duration of wet and dry cycles as well as the period can be independently investigated. Depending on cycling conditions, acetaldehyde or acetic acid production is favored with MLFR compared to CLFR. Results suggest both the opportunity and challenge of finding a way to tune the cycling parameters for producing the most appropriate product. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Heterogeneous catalytic ozonation of ciprofloxacin in water with carbon nanotube supported manganese oxides as catalyst

    International Nuclear Information System (INIS)

    Highlights: ► Ciprofloxacin in water was degraded by heterogeneous catalytic ozonation. ► MnOx were supported on MWCNTs to serve as catalyst for ozonation. ► MnOx/MWCNT exhibited highly catalytic activity on ozonation of ciprofloxacin in water. ► MnOx/MWCNT resulted in effective antibacterial activity inhibition on ciprofloxacin. ► MnOx/MWCNT promoted the generation of hydroxyl radicals. - Abstract: Carbon nanotube-supported manganese oxides (MnOx/MWCNT) were used as catalysts to assist ozone in degrading ciprofloxacin in water. Manganese oxides were successfully loaded on multi-walled carbon nanotube surfaces by simply impregnating the carbon nanotube with permanganate solution. The catalytic activities of MnOx/MWCNT in ciprofloxacin ozonation, including degradation, mineralization effectiveness, and antibacterial activity change, were investigated. The presence of MnOx/MWCNT significantly elevated the degradation and mineralization efficiency of ozone on ciprofloxacin. The microbiological assay with a reference Escherichia coli strain indicated that ozonation with MnOx/MWCNT results in more effective antibacterial activity inhibition of ciprofloxacin than that in ozonation alone. The effects of catalyst dose, initial ciprofloxacin concentration, and initial pH conditions on ciprofloxacin ozonation with MnOx/MWCNT were surveyed. Electron spin resonance trapping was applied to assess the role of MnOx/MWCNT in generating hydroxyl radicals (HO·) during ozonation. Stronger 5,5-dimethyl-1-pyrroline-N-oxide–OH signals were observed in the ozonation with MnOx/MWCNT compared with those in ozonation alone, indicating that MnOx/MWCNT promoted the generation of hydroxyl radicals. The degradation of ciprofloxacin was studied in drinking water and wastewater process samples to gauge the potential effects of water background matrix on MnOx/MWCNT catalytic ozonation.

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

    Science.gov (United States)

    Kim, Sang Chai; Nahm, Seung Won; Shim, Wang Geun; Lee, Jae Wook; Moon, Hee

    2007-03-01

    To recycle the spent catalyst for the removal of VOCs, the benzene, toluene, and xylene (BTX) complete oxidations were studied over pretreated palladium based spent catalyst in a fixed bed flow reactor system at atmospheric pressure. Two different pretreatment methods with gas (air and hydrogen) and acid aqueous solution (HCl, H(2)SO(4), HNO(3), H(3)PO(4) and CH(3)COOH) were used to investigate the catalytic activity of spent catalyst. The properties of the spent and pretreated Pd based catalyst were characterized by XRD, BET, TEM, ICP, and XPS. The results of light-off curves indicate that the catalytic activity of toluene oxidation for pretreated samples is in the order of hydrogen>air>HNO(3)>CH(3)COOH>H(2)SO(4)>H(3)PO(4)>HCl. In addition, the air and the acid aqueous pretreated catalyst activities were significantly decreased compared to that of the spent (or parent) catalyst. Moreover, hydrogen pretreated (or reduced) catalysts having mainly metallic form show the best performance in removing the toluene vapours compared to other pretreated samples. The reduction temperature made a significant difference in the catalytic performance of the spent catalyst pretreated with hydrogen. XPS results clearly supported that the palladium state of the spent catalysts pretreated at 300 degrees C was shifted more toward metallic form than other reduced catalysts. Furthermore, the results of a long-term test and catalytic activity of aromatic hydrocarbons also supported that the hydrogen pretreated spent catalyst was a good candidate for removing toxic compounds. PMID:16919389

  9. Catalytic combustion of benzene over CuO-CeO2 mixed oxides.

    Science.gov (United States)

    Jung, Won Young; Lim, Kwon-Taek; Hong, Seong-Soo

    2014-11-01

    Catalytic combustion of benzene over CuO-CeO2 mixed oxides has been investigated. The CuO-CeO2 mixed oxides were prepared by the combustion method using malic acid as an organic fuel and characterized by XRD, XPS and TPR. For the CuO-CeO2 catalyst with a Cu/(Cu + Ce) molar ratio of more than 0.4, highly dispersed copper oxide species were shown at 2θ = 35.5 degrees and 38.8 degrees. The CuO-CeO2 catalyst prepared using 2.0 M malic acid showed the highest activity, with conversion reaching nearly 100% at 350 degrees C. In addition, the highest activity is shown on Cu0.40 (the index denotes the molar ratio Cu/(Cu + Ce)) sample and then it decreases on Cu0.5 and Cu0.7 samples. PMID:25958554

  10. Electro-catalytic effect of manganese oxide on oxygen reduction at teflonbonded carbon electrode

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Oxygen reduction(OR)on Teflon-bonded carbon electrodes with manganese oxide as catalyst in 6 mol/L KOH solution was investigated using AC impedance spectroscopy combined with other techniques. For OR at this electrode, the Tafel slope is-0.084V/dec and the apparent exchange current density is (1.02-3.0)×10-7 A/cm2. In the presence of manganese oxide on carbon electrode,the couple Mn3+/Mn4+ reacts with the O2 adsorbed on carbon sites forming O2- radicals and acceletes the dismutation of O2-, which contributes to the catalytic effect of manganese oxide for OR reaction.

  11. Catalytic ozonation of sulfosalicylic acid over manganese oxide supported on mesoporous ceria.

    Science.gov (United States)

    Xing, Shengtao; Lu, Xiaoyang; Liu, Jia; Zhu, Lin; Ma, Zichuan; Wu, Yinsu

    2016-02-01

    Manganese oxide supported on mesoporous ceria was prepared and used as catalyst for catalytic ozonation of sulfosalicylic acid (SA). Characterization results indicated that the manganese oxide was mostly incorporated into the pores of ceria. The synthesized catalyst exhibited high activity and stability for the mineralization of SA in aqueous solution by ozone, and more than 95% of total organic carbon was removed in 30 min under various conditions. Mechanism studies indicated that SA was mainly degraded by ozone molecules, and hydroxyl radical reaction played an important role for the degradation of its ozonation products (small molecular organic acids). The manganese oxide in the pores of CeO2 improved the adsorption of small molecular organic acids and the generation of hydroxyl radicals from ozone decomposition, resulting in high TOC removal efficiency. PMID:26344143

  12. Catalytic selective oxidation or oxidative functionalization of methane and ethane to organic oxygenates

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Selective oxidation or oxidative functionalization of methane and ethane by both homogeneous and heterogeneous catalysis is presented concerning: (1) selective oxidation of methane and ethane to organic oxygenates by hydrogen peroxide in a water medium in the presence of homogeneous osmium catalysts, (2) selective oxidation of methane to formaldehyde over highly dispersed iron and copper heterogeneous catalysts, (3) selective oxidation of ethane to acetaldehyde and formaldehyde over supported molybdenum catalysts, and (4) oxidative carbonylation of methane to methyl acetate over heterogeneous catalysts containing dual sites of rhodium and iron.

  13. Treatment of biomass-gasification wastewaters by wet-air oxidation

    Energy Technology Data Exchange (ETDEWEB)

    English, C.J.

    1981-09-01

    Production of synthetic natural gas from gasification of biomass results in the generation of a high-strength wastewater that is difficult to treat by conventional means. This study investigated the use of wet air oxidation (WAO) as a treatment method for these wastewaters. A literature review was conducted to identify the suitability of WAO for the treatment of high-strength industrial wastewaters and to determine typical operating conditions for such treatment. Data presented in the literature showed that WAO should be suitable for treatment. Data presented in the literature showed that WAO should be suitable for treatment of biomass gasification wastewaters (BGW), and a laboratory treatability study was designed. BGW, having an initial chemical oxygen demand (COD) of 30,800 mg/1 and initial color of 183,000 APHA units, was treated in a laboratory autoclave for 20, 40, 60, 120, and 180 min at temperatures and pressures of 150/sup 0/C, 5.1 MPa (750 psi); 200/sup 0/C, 6.9 MPa (1000 psi); 250/sup 0/C, 10.3 MPa (1500 psi); and 300/sup 0/C, 13.8 MPa (2000 psi). Maximum COD removals of 0% for the 150/sup 0/C, 5.2 MPa (750 psi) runs; 40% for the 200/sup 0/C, 6.9 MPa (1000 psi) runs, 55% for the 250/sup 0/C, 10.3 MPa (1500 psi) runs; and 85% for the 300/sup 0/C, 13.8 MPa (2000 psi) runs were measured. Maximum color removals for these respective runs were 56%, 82%, 97%, and 99%. Initial removal rates of COD and color were observed to increase with reaction temperature. The experimental results suggest that oxidation of BGW organics by WAO occurs in a stepwise fashion with large organic molecules first being hydrolyzed and then partially oxidized to low molecular weight intermediates. Complete oxidation of these intermediates is more difficult and most easily accomplished at high reaction temperatures. The best application of WAO to treatment of BGW appears to be as a pretreatment to biological treatment and it is recommended that this application be investigated.

  14. Catalytic effects on methanol oxidation produced by cathodization of platinum electrodes.

    Science.gov (United States)

    Díaz, Verónica; Zinola, Carlos F

    2007-09-01

    A catalytic effect is found for methanol oxidation after new active surface states are produced on polycrystalline platinum by potentiostatic cathodization in acid media at room temperature. This procedure originates surface states not available on the original polycrystalline electrodes with unexpected cyclic voltammetric responses; i.e., at least four new peaks below 0.9 V are observed. The cathodization process also induces a rearrangement of the bulk platinum oxide, showing a defined peak at 1.2 V. The appearance of these new states is also proven by open-circuit potential decays. The electrocatalytic activity of these new surfaces in methanol oxidation is compared with that of the untreated electrodes by electrochemical impedance spectroscopy, chronoamperometry, and cyclic voltammetry. The cathodic procedure enhances the methanol oxidation voltammetric current peaks with charge density values higher than those on untreated platinum. The integration of chronoamperometric plots over 10 min in methanol acid media presents the largest difference between 0.6 and 0.7 V with respect to the original surface. Analysis of the impedance data shows that the values of polarization resistance for methanol oxidation on the cathodically treated platinum are lower than those of the original surface. According to the time constant values for methanol oxidation, the original surface can be considered less tolerant of the formation of catalytic poisons. A discussion of the most likely mechanism for the formation of the new active sites on platinum is presented here, assuming the presence of hydrogen subsurface states, ordered water clusters, and low-coordinated platinum atoms. PMID:17543323

  15. Dynamics of ultrathin V-oxide layers on Rh(111) in catalytic oxidation of ammonia and CO.

    Science.gov (United States)

    von Boehn, B; Preiss, A; Imbihl, R

    2016-07-20

    Catalytic oxidation of ammonia and CO has been studied in the 10(-4) mbar range using a catalyst prepared by depositing ultra-thin vanadium oxide layers on Rh(111) (θV ≈ 0.2 MLE). Using photoemission electron microscopy (PEEM) as a spatially resolving method, we observe that upon heating in an atmosphere of NH3 and O2 the spatial homogeneity of the VOx layer is removed at 800 K and a pattern consisting of macroscopic stripes develops; at elevated temperatures this pattern transforms into a pattern of circular VOx islands. Under reaction conditions the neighboring VOx islands become attracted by each other and coalesce. Similar processes of pattern formation and island coalescence are observed in catalytic CO oxidation. Reoxidation of the reduced VOx catalyst proceeds via surface diffusion of oxygen adsorbed onto Rh(111). A pattern consisting of macroscopic circular VOx islands can also be obtained by heating a Rh(111)/VOx catalyst in pure O2. PMID:27380822

  16. Catalytic oxidation of anionic surfactants by electrochemical oxidation with CuO-Co2O3-PO43- modified kaolin

    International Nuclear Information System (INIS)

    A new catalytic oxidation of anionic surfactants by electrochemistry method was designed and used to investigate the removal of anionic surfactant from simulated wastewater. Synergetic effect on COD removal was studied when integrating the electrochemical reactor, using porous graphite as anode and cathode, with the effective CuO-Co2O3-PO43- modified kaolin catalyst in a single undivided cell. The result showed that this combined process could effectively remove anionic surfactant. Its COD removal efficiency was much higher than those individual processes and could reach up to 90% in 60 min. The operating parameters such as initial pH, cell voltage, and current intensity were also investigated. Possible theory for COD removal was also proposed to predict the role of modified kaolin, electro-catalysis and oxidation in the combined process. The pollutants in wastewater could be decreased by the high reactive OH· that produced on the surface of catalyst by the decomposition of electrochemical generated H2O2. The result indicates that the catalytic oxidation by electrochemistry method is a promising wastewater treatment technique

  17. Anaerobic treatability of liquid residue from wet oxidation of sewage sludge.

    Science.gov (United States)

    Bertanza, Giorgio; Galessi, Raniero; Menoni, Laura; Pedrazzani, Roberta; Salvetti, Roberta; Zanaboni, Sabrina

    2015-05-01

    Wet Oxidation (WO) of sewage sludge is a chemical oxidation of sludge at high temperatures and pressures by means of an oxygen-containing gas. The liquid stream originated by WO is easily biodegradable, and therefore, the recirculation to the biological Waste Water Treatment Plant (WWTP) may be a feasible solution. However, the WO effluent has a residual organic and nitrogen content so that its treatment may be required when the receiving WWTP has no surplus treatment capacity left. The aim of this research was the assessment of the anaerobic treatability of the WO liquid residue, in order to reduce the organic load to be recirculated to the WWTP, simultaneously promoting energy recovery. For this purpose, the liquid residue obtained during full scale WO tests on two different types of sludge was submitted to anaerobic digestion in a continuous flow pilot reactor (V = 5 L). Furthermore, batch tests were carried out in order to evaluate possible inhibition factors. Experimental results showed that, after the start-up/acclimation period (~130 days), Chemical Oxygen Demand (COD) removal efficiency was stably around 60% for about 120 days, despite the change in operating conditions. In the last phase of the experimental activity, COD removal reached 70% under the following treatment conditions: Hydraulic Retention Time (HRT) = 20 days, Volumetric Organic Loading Rate (VOLR) = 0.868 kg COD/m(3)/day, Organic Loading Rate per Volatile Suspended Solids (OLRvss) = 0.078 kg COD/kg VSS/day, temperature (T) = 36.5 °C, pH = 8. Energy balance calculation demonstrated anaerobic treatment sustainability. PMID:25035054

  18. Toluene removal by oxidation reaction in spray wet scrubber: experimental, modeling and optimization

    Directory of Open Access Journals (Sweden)

    Roumporn Nikom

    2006-11-01

    Full Text Available Toluene, an important volatile organic compound (VOC, is used in many kinds of industries, such as painting, printing, coating, and petrochemical industries. The emission of toluene causes serious air pollution, odor problem, flammability problem and affects human health. This paper proposes the removal of toluene from waste air using a spray wet scrubber combining the absorption and oxidation reaction. Aqueous sodium hypochlorite (NaOCl solution was used as the scrubbing liquid in the system. NaOCl, the strongest oxidative agent, presents an effective toluene removal. As the scrubbed toluene is reacted, recirculation of the scrubbing liquid could be operated with a constant removal efficiency throughout the operting time. The investigated variables affecting the removal efficiency were air flow rate, inlet toluene concentration, NaOCl concentration, scrubbing liquid flow rate and size of spray nozzle. Influence of the scrubbing parameters was experimentally studied to develop a mathematical model of the toluene removal efficiency. The removal model reveals that the increase of scrubbing liquid flow rate, toluene concentration, and NaOCl concentration together with the decrease of air flow rate and size of spray nozzle can increase the toluene removal efficiency. Optimization problem with an objective function and constraints was set to provide the maximum toluene removal efficiency and solved by Matlab optimization toolbox. The optimization constraints were formed from the mathematical model and process limitation. The solution of the optimization was an air flow rate of 100 m3/h, toluene concentration of 1500 ppm, NaOCl concentration of 0.02 mol/l, NaOCl solution feed rate of 0.8 m3/h, and spray nozzle size of 0.5 mm. Solution of the optimization gave the highest toluene removal efficiency of 91.7%.

  19. Determination of boron in graphite by a wet oxidation decomposition/curcumin photometric method

    International Nuclear Information System (INIS)

    The wet oxidation decomposition of graphite materials has been studied for the accurate determination of boron using a curcumin photometric method. A graphite sample of 0.5 g was completely decomposed with a mixture of 5 ml of sulfuric acid, 3 ml of perchloric acid, 0.5 ml of nitric acid and 5 ml of phosphoric acid in a silica 100 ml Erlenmeyer flask fitted with an air condenser at 200degC. Any excess of perchloric and nitric acids in the solution was removed by heating on a hot plate at 150degC. Boron was distilled with methanol, and then recovered in 10 ml of 0.2 M sodium hydroxide. The solution was evaporated to dryness. To the residue were added curcumin-acetic acid and sulfuric-acetic acid. The mixture was diluted with ethanol, and the absorbance at 555 nm was measured. The addition of 5 ml of phosphoric acid proved to be effective to prevent any volatilization loss of boron during decomposition of the graphite sample and evaporation of the resulting solution. The relative standard deviation was 4-8% for samples with 2 μg g-1 levels of boron. The results on CRMs JAERI-G5 and G6 were in good agreement with the certified values. (author)

  20. Decomposition and Mineralization of Dimethyl Phthalate in an Aqueous Solution by Wet Oxidation

    Directory of Open Access Journals (Sweden)

    Dar-Ren Ji

    2015-01-01

    Full Text Available Dimethyl phthalate (DMP was treated via wet oxygen oxidation process (WOP. The decomposition efficiency ηDMP of DMP and mineralization efficiency ηTOC of total organic carbons were measured to evaluate the effects of operation parameters on the performance of WOP. The results revealed that reaction temperature T is the most affecting factor, with a higher T offering higher ηDMP and ηTOC as expected. The ηDMP increases as rotating speed increases from 300 to 500 rpm with stirring enhancement of gas liquid mass transfer. However, it exhibits reduction effect at 700 rpm due to purging of dissolved oxygen by overstirring. Regarding the effects of pressure PT, a higher PT provides more oxygen for the forward reaction with DMP, while overhigh PT increases the absorption of gaseous products such as CO2 and decomposes short-chain hydrocarbon fragments back into the solution thus hindering the forward reaction. For the tested PT of 2.41 to 3.45 MPa, the results indicated that 2.41 MPa is appropriate. A longer reaction time of course gives better performance. At 500 rpm, 483 K, 2.41 MPa, and 180 min, the ηDMP and ηTOC are 93 and 36%, respectively.

  1. Simultaneous removal of methylene blue and copper(II) ions by photoelectron catalytic oxidation using stannic oxide modified iron(III) oxide composite electrodes

    International Nuclear Information System (INIS)

    Highlights: • Photoelectron catalytic oxidation was used for methylene blue and Cu2+ removal. • SnO2/Fe2O3 was prepared and characterized for use as photoanodes and photocathodes. • Optimal reaction conditions were determined for methylene blue and Cu2+ removal. • Methylene blue removal followed the Langmuir–Freundlich–Hinshelwood kinetic model. • Cu2+ removal followed the first-order rate model. - Abstract: Stannic oxide modified Fe(III) oxide composite electrodes (SnO2/Fe2O3) were synthesized for simultaneously removing methylene blue (MB) and Cu(II) from wastewater using photoelectron catalytic oxidation (PEO). The SnO2/Fe2O3 electrodes were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoelectrochemical techniques. The removal of MB and Cu(II) by PEO using the SnO2/Fe2O3 composite electrodes was studied in terms of reaction time, electric current density, and pH of the electrolyte. The kinetics of the reactions were investigated using batch assays. The optimal reaction time, pH, and electric current density of the PEO process were determined to be 30 min, 6.0, and 10 mA/cm2, respectively. The removal rates of MB from wastewater treated by PEO and electron catalytic oxidation process were 84.87% and 70.64%, respectively, while the recovery rates of Cu(II) were 91.75% and 96.78%, respectively. The results suggest that PEO is an effective method for the simultaneous removal of MB and Cu(II) from wastewater, and the PEO process exhibits a much higher removal rate for MB and Cu(II) compared to the electron catalytic oxidation process. Furthermore, the removal of MB was found to follow the Langmuir–Freundlich–Hinshelwood kinetic model, whereas the removal of Cu(II) fitted well to the first-order reaction model

  2. Acid Separation, Catalytic Oxidation and Coagulation for ATC Waste Liquid Treatment

    Institute of Scientific and Technical Information of China (English)

    DING Xiaoling; JIA Chunning

    2005-01-01

    It is difficult to treat 2-amino-thiazoline-4-carboxylic acid (ATC) waste liquid effectively at present for its characteristics of high chemical oxygen demand (COD), high salinity and low biodegradability. In order to solve this problem, this paper presents several kinds of physical-chemical treatment unit techniques, including acid separation, catalytic oxidation and coagulation. First of all, acid separation was adopted to precipitate relevant organics at isoelectric point. When the temperature and pH value of acid separation were controlled at about 5 ℃ and 2.2 respectively, the COD removal rate could reach 27.6%. Secondly, oxidation was used to break chemical constitution of refractory organics. The optimal reaction parameters of catalytic oxidation should be 20 ℃, pH adjusted to 5.0 and [Fe2+] 300 mg/L. Then with 5% H 2O 2 added and after one-hour reaction, the COD removal rate could achieve about 52%. Finally, coagulation was adopted to remove a portion of refractory organics, and 15% polymeric molysite flocculant was the best for the coagulation, and the COD removal rate could reach about 15%. Therefore, the proposed feasible process of physical-chemical pretreatment for ATC waste liquid could have about 70% COD removed in total.

  3. Catalytic Role of Manganese Oxides in Prebiotic Nucleobases Synthesis from Formamide

    Science.gov (United States)

    Bhushan, Brij; Nayak, Arunima; Kamaluddin

    2016-06-01

    Origin of life processes might have begun with the formation of important biomonomers, such as amino acids and nucleotides, from simple molecules present in the prebiotic environment and their subsequent condensation to biopolymers. While studying the prebiotic synthesis of naturally occurring purine and pyrimidine derivatives from formamide, the manganese oxides demonstrated not only good binding for formamide but demonstrated novel catalytic activity. A novel one pot manganese oxide catalyzed synthesis of pyrimidine nucleobases like thymine is reported along with the formation of other nucleobases like purine, 9-(hydroxyacetyl) purine, cytosine, 4(3 H)-pyrimidinone and adenine in acceptable amounts. The work reported is significant in the sense that the synthesis of thymine has exhibited difficulties especially under one pot conditions and also such has been reported only under the catalytic activity of TiO2. The lower oxides of manganese were reported to show higher potential as catalysts and their existence were favored by the reducing atmospheric conditions prevalent on early Earth; thereby confirming the hypothesis that mineral having metals in reduced form might have been more active during the course of chemical evolution. Our results further confirm the role of formamide as a probable precursor for the formation of purine and pyrimidine bases during the course of chemical evolution and origin of life.

  4. Catalytic Role of Manganese Oxides in Prebiotic Nucleobases Synthesis from Formamide.

    Science.gov (United States)

    Bhushan, Brij; Nayak, Arunima; Kamaluddin

    2016-06-01

    Origin of life processes might have begun with the formation of important biomonomers, such as amino acids and nucleotides, from simple molecules present in the prebiotic environment and their subsequent condensation to biopolymers. While studying the prebiotic synthesis of naturally occurring purine and pyrimidine derivatives from formamide, the manganese oxides demonstrated not only good binding for formamide but demonstrated novel catalytic activity. A novel one pot manganese oxide catalyzed synthesis of pyrimidine nucleobases like thymine is reported along with the formation of other nucleobases like purine, 9-(hydroxyacetyl) purine, cytosine, 4(3 H)-pyrimidinone and adenine in acceptable amounts. The work reported is significant in the sense that the synthesis of thymine has exhibited difficulties especially under one pot conditions and also such has been reported only under the catalytic activity of TiO2. The lower oxides of manganese were reported to show higher potential as catalysts and their existence were favored by the reducing atmospheric conditions prevalent on early Earth; thereby confirming the hypothesis that mineral having metals in reduced form might have been more active during the course of chemical evolution. Our results further confirm the role of formamide as a probable precursor for the formation of purine and pyrimidine bases during the course of chemical evolution and origin of life. PMID:26758444

  5. Mercury Oxidation over Selective Catalytic Reduction (SCR) Catalysts - Ph.d. thesis Karin Madsen

    DEFF Research Database (Denmark)

    Madsen, Karin

    The vanadium-based SCR catalyst used for NOx-control promotes the oxidation of elemental mercury Hg0 to Hg2+ in flue gases from coal-fired power plants. Hg2+ is water soluble and can effectively be captured in a wet scrubber. This means that the combination of an SCR with a wet FGD can offer...... an effective control option for mercury. Laboratory experiments have been carried out to quantify the Hg0 oxidation that can be achieved over commercial SCR catalysts for different gas compositions, operating conditions and catalyst types. The following three net reactions have been identified as relevant...... for the mercury chemistry over the SCR: R1. 2 HCl + Hg0 + 1/2 O2 ↔ HgCl2 + H2O R2. 2 NH3 + 3 HgCl2 ↔ N2 + 3 Hg0 + 6 HCl R3. 2 NO + 2 NH3 + 1/2 O2 ↔ 2 N2 + 3 H2O where reaction R1 is the oxidation of Hg0 by HCl, reaction R2 is the reduction of HgCl2 by NH3 and reaction R3 is the DeNOx reaction. The importance...

  6. Catalytic oxidation of 4-tert-butyltoluene over Ti-MCM-41

    Institute of Scientific and Technical Information of China (English)

    Wei Hua Yu; Chun Hui Zhou; Xiang Sheng Xu; Zhong Hua Ge

    2007-01-01

    The surface-grafted titanium MCM-41 materials were prepared by anchoring titanocene onto the inner walls of MCM-41. The materials were characterized by powder X-ray diffraction (XRD), N2 adsorption-desorption isotherm and diffuse reflectance UV-visible (UV-vis) spectroscopies. The catalytic properties of Ti-MCM-41 were tested in oxidation of 4-tert-butyltoluene with tert-butylhydroperoxide (TBHP) in liquid phase. MCM-41 with loading 4.8 mol% Ti gave the maximal conversions of 23.6% of 4-tert-butyltoluene with a complete selectivity to 4-tert-butylbenzaldehyde.

  7. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  8. MWW-type titanosilicate synthesis, structural modification and catalytic applications to green oxidations

    CERN Document Server

    Wu, Peng; Xu, Le; Liu, Yueming; He, Mingyuan

    2013-01-01

    This book provides a comprehensive review of a new generation of selective oxidation titanosilicate catalysts with the MWW topology (Ti-MWW) based on the research achievements of the past 12 years. It gives an overview of the synthesis, structure modification and catalytic properties of Ti-MWW. Ti-MWW can readily be prepared by means of direct hydrothermal synthesis with crystallization-supporting agents, using dual-structure-directing agents and a dry-gel conversion technique. It also can be post-synthesized through unique reversible structure transformation and liquid-phase isomorphous subst

  9. Catalytic aerobic oxidation and tandem enantioselective cycloaddition in cascade multicomponent synthesis.

    Science.gov (United States)

    Potowski, Marco; Merten, Christian; Antonchick, Andrey P; Waldmann, Herbert

    2015-03-23

    An efficient multicomponent cascade transformation for the highly diastereo- and enantioselective synthesis of complex natural product inspired polycyclic products from simple starting materials is described. The cascade is initiated by copper-catalyzed aerobic CH oxidation of cyclopentadiene to cyclopentadienone followed by double catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides. The cascade synthesis efficiently yields structurally complex 5,5,5-tricyclic products with eight stereocenters with good yields and excellent diastereo- and enantiocontrol using one catalyst. PMID:25676025

  10. Possible nature of the catalytic activity of metalloporphyrins in reactions to nonchain oxidation of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Solov' eva, A.B.; Karakozova, E.I.; Karmilova, L.V.; Timashev, S.F.

    1985-05-01

    The authors hypothesize that an intermediate cyclic complex, TPPMn(II) with oxygen and the olefin, is formed during the catalytic oxidation of olefins with a varying degree of substitution in the double bond of the system: molecular oxygen-TPP MnCl-NaBH/sub 4/ (TPP: tetraphenylporphyrin). They hypothesize that strong electrical fields in the submicrovicinity of the metalloporphyrin (MP) molecule favor the formation of a cyclic intermediate complex. They conclude that the possibility of the formation of a cyclic intermediate complex is verified on the basis of data on the state of the central reduced ion and the type of coordination of the oxygen molecule.

  11. Rare earth oxide aero- and xerogels. Tuning porosity and catalytic properties

    International Nuclear Information System (INIS)

    Heterogeneous catalysts to this day are still largely developed on the basis of trial and error. This is due to the great difficulty of creating custom-designed structures at the nanometer scale using traditional preparation methods. In the course of recent rapid developments in the material sciences, however, it has become possible to create materials with custom-designed properties from the macroscopic down into the nanometer range. The purpose of the present study was to make use of this potential for catalysis. The task was to modify the porosity and composition of selected rare earth oxides that promise well as catalysts with the goal of obtaining good results in terms of oxidative reactions and oxidative coupling. One major focus was on chemical sol-gel methods and in particular on what is referred to as the epoxide addition method. Extensive work was put into the characterisation and catalytic testing of aerogels and xerogels of pure rare earth oxides as well as of hybrid systems of rare earth oxides and aluminium oxide. Furthermore, thin xerogel films and macroporous monoliths were produced, the latter using a direct foaming method. The results of this work confirm the high potential of sol-gel chemistry for making porous materials of variable and controllable porosity and composition available for heterogeneous catalysis and creating more powerful catalysts.

  12. Oxidation Behavior of Mo-Si-B Alloys in Wet Air; TOPICAL

    International Nuclear Information System (INIS)

    Multiphase composite alloys based on the Mo-Si-B system are candidate materials for ultra-high temperature applications. In non load-bearing uses such as thermal barrier coatings or heat exchangers in fossil fuel burners, these materials may be ideally suited. The present work investigated the effect of water vapor on the oxidation behavior of Mo-Si-B phase assemblages. Three alloys were studied: Alloy 1= Mo(sub 5)Si(sub 3)B(sub x) (T1)- MoSi(sub 2)- MoB, Alloy 2= T1- Mo(sub 5)SiB(sub 2) (T2)- Mo(sub 3)Si, and Alloy 3= Mo- T2- Mo(sub 3)Si. Tests were conducted at 1000 and 1100C in controlled atmospheres of dry air and wet air nominally containing 18, 55, and 150 Torr H(sub 2)O. The initial mass loss of each alloy was approximately independent of the test temperature and moisture content of the atmosphere. The magnitude of these initial losses varied according to the Mo content of the alloys. All alloys formed a continuous, external silica scale that protected against further mass change after volatilization of the initially formed MoO(sub 3). All alloys experienced a small steady state mass change, but the calculated rates cannot be quantitatively compared due to statistical uncertainty in the individual mass measurements. Of particular interest is that Alloy 3, which contains a significant volume fraction of Mo metal, formed a protective scale. All alloys formed varying amounts of subscale Mo and MoO(sub 2). This implies that oxygen transport through the external silica scale has been significantly reduced. For all alloys, water vapor accelerated the growth of a multiphase interlayer at the silica scale/unoxidized alloy interface. This interlayer is likely composed of fine Mo and MoO(sub 2) that is dispersed within a thin silica matrix. Alloy 3 was particularly sensitive to water accelerated growth of this interlayer. At 1100 C, the scale thickness after 300 hours increased from about 20 mm in dry air to nearly 100 mm in wet air

  13. Conditioning of Si-interfaces by wet-chemical oxidation: Electronic interface properties study by surface photovoltage measurements

    Energy Technology Data Exchange (ETDEWEB)

    Angermann, Heike, E-mail: angermann@helmholtz-berlin.de

    2014-09-01

    Highlights: • Determination of electronic interface properties by contact-less surface photovoltage (SPV) technique. • Systematic correlations of substrate morphology and surface electronic properties. • Optimization of surface pre-treatment for flat, saw damage etched, and textured Si solar cell substrates. • Ultra-thin passivating Si oxide layers with low densities of rechargeable states by wet-chemical oxidation and subsequent annealing. • Environmentally acceptable processes, utilizing hot water, diluted HCl, or ozone low cost alternative to current approaches with concentrated chemicals. • The effect of optimized wet-chemical pre-treatments can be preserved during subsequent layer deposition. - Abstract: The field-modulated surface photovoltage (SPV) method, a very surface sensitive technique, was utilized to determine electronic interface properties on wet-chemically oxidized and etched silicon (Si) interfaces. The influence of preparation-induced surface micro-roughness and un-stoichiometric oxides on the resulting the surface charge, energetic distribution D{sub it}(E), and density D{sub it,min} of rechargeable states was studied by simultaneous, spectroscopic ellipsometry (SE) measurements on polished Si(111) and Si(100) substrates. Based on previous findings and new research, a study of conventional and newly developed wet-chemical oxidation methods was established, correlating the interactions between involved oxidizing and etching solutions and the initial substrate morphology to the final surface conditioning. It is shown, which sequences of wet-chemical oxidation and oxide removal, have to be combined in order to achieve atomically smooth, hydrogen terminated surfaces, as well as ultra-thin oxide layers with low densities of rechargeable states on flat, saw damage etched, and textured Si substrates, as commonly applied in silicon device and solar cell manufacturing. These conventional strategies for wet-chemical pre-treatment are mainly

  14. Synthesis, characterization, and catalytic application of ordered mesoporous carbon–niobium oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Juan-Li; Gao, Shuang; Liu, Chun-Ling; Liu, Zhao-Tie; Dong, Wen-Sheng, E-mail: wsdong@snnu.edu.cn

    2014-11-15

    Graphical abstract: The ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process. - Highlights: • Ordered mesoporous carbon–niobium oxide composites were synthesized. • The content of Nb{sub 2}O{sub 5} in the composites could be tuned from 38 to 75%. • Niobium species were highly dispersed in amorphous carbon framework walls. • The composites exhibited good catalytic performance in the dehydration of fructose. - Abstract: Ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process using phenolic resol as carbon source, niobium chloride as precursor and amphiphilic triblock copolymer Pluronic F127 as template. The resulting materials were characterized using a combination of techniques including differential scanning calorimetry–thermogravimetric analysis, N{sub 2} physical adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show that with increasing the content of Nb{sub 2}O{sub 5} from 38 to 75% the specific surface area decreases from 306.4 to 124.5 m{sup 2} g{sup −1}, while the ordered mesoporous structure is remained. Niobium species is well dispersed in the amorphous carbon framework. The mesoporous carbon–niobium oxide composites exhibit high catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural. A 100% conversion of fructose and a 76.5% selectivity of 5-hydroxymethylfurfural were obtained over the carbon–niobium oxide composite containing 75% Nb{sub 2}O{sub 5} under the investigated reaction conditions.

  15. Oscillations, period doublings, and chaos in CO oxidation and catalytic mufflers.

    Science.gov (United States)

    Marek, Milos; Schejbal, Matyás; Kocí, Petr; Nevoral, Vladislav; Kubícek, Milan; Hadac, Otto; Schreiber, Igor

    2006-09-01

    Early experimental observations of chaotic behavior arising via the period-doubling route for the CO catalytic oxidation both on Pt(110) and Ptgamma-Al(2)O(3) porous catalyst were reported more than 15 years ago. Recently, a detailed kinetic reaction scheme including over 20 reaction steps was proposed for the catalytic CO oxidation, NO(x) reduction, and hydrocarbon oxidation taking place in a three-way catalyst (TWC) converter, the most common reactor for detoxification of automobile exhaust gases. This reactor is typically operated with periodic variation of inlet oxygen concentration. For an unforced lumped model, we report results of the stoichiometric network analysis of a CO reaction subnetwork determining feedback loops, which cause the oscillations within certain regions of parameters in bifurcation diagrams constructed by numerical continuation techniques. For a forced system, numerical simulations of the CO oxidation reveal the existence of a period-doubling route to chaos. The dependence of the rotation number on the amplitude and period of forcing shows a typical bifurcation structure of Arnold tongues ordered according to Farey sequences, and positive Lyapunov exponents for sufficiently large forcing amplitudes indicate the presence of chaotic dynamics. Multiple periodic and aperiodic time courses of outlet concentrations were also found in simulations using the lumped model with the full TWC kinetics. Numerical solutions of the distributed model in two geometric coordinates with the CO oxidation subnetwork consisting of several tens of nonlinear partial differential equations show oscillations of the outlet reactor concentrations and, in the presence of forcing, multiple periodic and aperiodic oscillations. Spatiotemporal concentration patterns illustrate the complexity of processes within the reactor. PMID:17014241

  16. Facile synthesis of magnetically separable reduced graphene oxide/magnetite/silver nanocomposites with enhanced catalytic activity.

    Science.gov (United States)

    Ji, Zhenyuan; Shen, Xiaoping; Yue, Xiaoyang; Zhou, Hu; Yang, Juan; Wang, Yuqin; Ma, Lianbo; Chen, Kangmin

    2015-12-01

    In this study, the combination of magnetite (Fe3O4) with reduced graphene oxide (RGO) generates a new hybrid substrate for the dispersion of noble metal nanoparticles. Well-dispersed silver (Ag) nanoparticles loaded on the surface of Fe3O4 modified RGO are achieved by an efficient two-step approach. Through reducing Ag(+) ions, highly dispersed Ag nanoparticles are in-situ formed on the RGO/Fe3O4 substrate. It is found that the existence of Fe3O4 nanocrystals can significantly improve the dispersity and decrease the particle size of the in-situ formed Ag nanoparticles. Magnetic study reveals that the as-prepared RGO/Fe3O4/Ag ternary nanocomposites display room-temperature superparamagnetic behavior. The catalytic properties of the RGO/Fe3O4/Ag ternary nanocomposites were evaluated with the reduction of 4-nitrophenol into 4-aminophenol as a model reaction. The as-synthesized RGO/Fe3O4/Ag ternary catalysts exhibit excellent catalytic stability and much higher catalytic activity than the corresponding RGO/Ag catalyst. Moreover, the RGO/Fe3O4/Ag catalysts can be easily magnetically separated for reuse. This study further demonstrates that nanoparticles modified graphene can act as an effective hybrid substrate for the synthesis of multi-component and multifunctional graphene-based composites. PMID:26263498

  17. Radiation influencing of catalytic activity and reactivity of selected mixed oxides

    International Nuclear Information System (INIS)

    Two mixed oxides, viz. CuO-Bi2O3 and NiO-Bi2O3, of various compositions were studied with respect to their physico-chemical properties, catalytic activity, and chemical reactivity, using hydrogen peroxide decomposition and hydrogen reduction as the test reactions. Pre-irradiation of the CuO-Bi2O3 catalyst with 60Co gamma rays (0.5, 1.0, 1.5, or 3.0 MGy) and accelerated electrons (4 MeV) brought about changes in the mutual influence of the system components accompanied by formation of induced catalytic sites. The reduction rate decrease in the two side regions after electron irradiation and after gamma irradiation applying the extremely high dose of 3 MGy can be correlated with the increase in the concentration of the strongly bonded oxygen forms, giving rise to centres for donor hydrogen chemisorption. The NiO-Bi2O3 system seems to be less stable than the CuO-Bi2O3 system. Gamma irradiation (1 MGy) in water brought about decrease in the catalytic activity but no change in the mutual influence of the two components of the system. In the same conditions the reduction rate decreased appreciably, whereas pre-irradiation in air led to acceleration of the reduction process. This can be ascribed to a higher concentration of the stabilized charge defects, enhancing the reactivity of the interface. (author). 4 figs., 6 refs

  18. Photo catalytic Oxidation of Carbon Monoxide over NiO/SnO2 Nano composites under UV Irradiation

    International Nuclear Information System (INIS)

    The NiO/SnO2 nano composites have been prepared by the simple coprecipitation method and further characterized by the XRD, SEM, TEM, UV-Vis, and BET. X-ray diffraction (XRD) data analyses indicate the exclusive formation of nano sized particles with rutile-type phase (tetragonal SnO2) for Ni contents below 10 mol%. Only above 10 mol% Ni, the formation of a second NiO-related phase has been determined. The particle size is in the range from 12 to 6 nm. It decreases with increasing amounts of doping NiO. The morphology of NiO-doped SnO2 nanocrystalline powders is spherical, and the distribution of particle size is uniform, as seen from transmission electron microscopy (TEM). The photo catalytic oxidation of CO over NiO/SnO2 photo catalyst has been investigated under UV irradiation. Effects of NiO loading on SnO2, photo catalyst loading, and reaction time on photo catalytic oxidation of CO have been systematically studied. Compared with pure SnO2, the 33.3 mol% NiO/SnO2 composite exhibited approximately twenty fold enhancement of photo catalytic oxidation of CO. Our results provide a method for pollutants removal. Due to simple preparation, high photo catalytic oxidation of CO, and low cost, the NiO/SnO2 photo catalyst will find wide application in the coming future of photo catalytic oxidation of CO

  19. Catalytic incineration of CO and VOC emissions over supported metal oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Per-Olof

    1999-05-01

    Catalytic incineration is one of the methods to reduce the emissions of CO and VOCs. Low operation temperature and low catalyst cost are essential parameters for catalytic incinerators. Pt/Al{sub 2}O{sub 3} catalysts are frequently used today, but the cheaper metal oxide catalysts can be very competitive if comparable overall activity is obtained. This thesis concerns how it is possible to decrease the operation temperature for supported metal oxide catalysts by using different supports, active metal oxides and additives. In the thesis it is demonstrated that different copper oxide based catalysts have the best activity and durability for complete oxidation among several tested metal oxide catalysts. CuO{sub x} supported on TiO{sub 2} and Al{sub 2}O{sub 3} showed increased activity with the CuO{sub x} loading up to the threshold coverage for formation of crystalline CuO particles, which is 12 {mu}mol/m{sup 2} on TiO{sub 2} and 6 {mu}mol/m{sup 2} on Al{sub 2}O{sub 3}. Up to the threshold coverage for CuO formation, well dispersed copper oxide species were formed on TiO{sub 2}, and a dispersed copper aluminate surface phase was formed on Al{sub 2}O{sub 3}. Durability tests showed accelerated sintering of TiO{sub 2} by copper, but stabilisation was possible by modification of the TiO{sub 2} with CeO{sub x} before the deposition of CuO{sub x}. The stabilisation was obtained by formation of a Ce-O-Ti surface phase. Addition of CeO{sub x} also enhanced the activity of the copper oxide species thanks to favourable interaction between the active copper oxide species and the CeO{sub x} on the support, which could be seen as increased reducibility in TPR experiments. The increased activity and reducibility was also observed for CuO{sub x} supported on ceria modified Al{sub 2}O{sub 3}. In this regard it was shown that CuO{sub x} deposited on CeO{sub 2}(001) surfaces was substantially more active for CO oxidation than copper oxide deposited on CeO{sub 2}(111) Surfaces. This

  20. Graphene oxide reduced and modified by environmentally friendly glycylglycine and its excellent catalytic performance

    International Nuclear Information System (INIS)

    An environmentally friendly new approach to prepare reduced graphene oxide (RGO) was developed by using glycylglycine (gly-gly) as both a reducing and stabilizing agent. Graphene oxide (GO) was transformed to RGO with the appropriate pH, temperature and reducing agent/GO ratio. The RGO was characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermo-gravimetric analysis, x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy. The RGO aqueous suspension showed extraordinary stability in the absence of any external stabilizing reagents. The XPS analysis showed that this excellent stability is due to modifications of the RGO nanosheets by the gly-gly molecules. The modified RGO complex with copper shows good catalytic performance for reduction of 4-nitrophenol to 4-aminophenol. (paper)

  1. Graphene oxide reduced and modified by environmentally friendly glycylglycine and its excellent catalytic performance

    Science.gov (United States)

    Zhang, Congcong; Chen, Mingxi; Xu, Xiaoyang; Zhang, Li; Zhang, Lei; Xia, Fengling; Li, Xichuan; Liu, Yu; Hu, Wenping; Gao, Jianping

    2014-04-01

    An environmentally friendly new approach to prepare reduced graphene oxide (RGO) was developed by using glycylglycine (gly-gly) as both a reducing and stabilizing agent. Graphene oxide (GO) was transformed to RGO with the appropriate pH, temperature and reducing agent/GO ratio. The RGO was characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermo-gravimetric analysis, x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy. The RGO aqueous suspension showed extraordinary stability in the absence of any external stabilizing reagents. The XPS analysis showed that this excellent stability is due to modifications of the RGO nanosheets by the gly-gly molecules. The modified RGO complex with copper shows good catalytic performance for reduction of 4-nitrophenol to 4-aminophenol.

  2. Electro-catalytic oxidation of phenol with Ti-base lead dioxide electrode

    Institute of Scientific and Technical Information of China (English)

    王东田; 魏杰; 于秀娟; 杨红

    2003-01-01

    The Ti-base PbO2 electrode prepared by electrodeposition of PbO2 on the surface of titanium was used for electro-catalytic oxidation of phenol in waste water. The experimental results show that the electrodeposition of PbO2 at a higher current density for a short time, then followed by a lower current density can get a compact and combinative PbO2 layer. The properties of a Ti/PbO2 electrode with an interlayer of oxide are the best. When this kind of electrode is used to treat phenol containing waste water, the phenol-removal rate is higher and the slot voltage is lower. In addition, by using the phenol-removal rate as an index, the influences of electrolysis current density, mass transfer condition and pH were studied and the optimal condition was confirmed.

  3. Tuning size and catalytic activity of nano-clusters of cobalt oxide

    Indian Academy of Sciences (India)

    R Venkat Narayan; Vinod Kanniah; Aruna Dhathathreyan

    2006-03-01

    Cobalt oxides were prepared by three different methods: (1) by reacting cobalt nitrate with oxalic acid, (2) co-precipitating cobalt nitrate with sodium carbonate, and (3) using sodium dodecyl sulphate as organic surfactant. All three samples were characterized before and after calcination by solvent extraction and the resulting products examined by IR spectroscopy. In the case of method 3, the removal of surfactant was followed by TGA studies. Products from all three methods were identified by XRD. Peaks in low angle XRD indicate the porous nature of the oxides. The morphology of the pores was studied by transmission electron microscopy. Some irregular pore structures were obtained for samples from methods 1 and 2, with an average size of 4-6 nm. Only the product from method 3 using SDS as template showed ordered structure and optimum size, and Brunauer-Emmet-Teller surface areas of the as-prepared, as well as the treated samples, exhibited H3 type hysteresis. The samples from the three methods were used as catalysts in the oxidation reaction of cyclohexane under mild conditions and the catalytic efficiency of the cobalt oxide was comparable with mesoporous cobalt oxides.

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

    Directory of Open Access Journals (Sweden)

    Sathaporn Chuepeng

    2012-01-01

    Full Text Available Problem statement: Gaseous emissions from gasoline engine such as carbon monoxide, unburned hydrocarbon and nitrogen oxides were usually reduced in three-way catalytic converter simultaneously around theoretical fuel and air combustion. Engine speed and load and other parameters were varied over a wide range of operating conditions, resulting in different exhaust gas composition and condition intake into catalytic converter. This work was studied the conversion of Nitric Oxide (NO in exhaust gas catalytic converter affected by gas velocity and inlet temperature using numerical modeling. Approach: The simulation was based on a one-dimensional time-dependent model within a single monolith channel of the converter. Upon certain assumptions, the study was considered heterogeneous combustion reaction between gas and solid phases based on lumped kinetic reactions. In this study, constants and variables used for mass and heat transfers were dependent on gas or solid phase temperature and mole fraction. Finite difference scheme incorporated with the generated computer code was established for solving species and energy balances within gas and solid phases. Results: The NO conversion was increased with transient period in initial and reached steady state at different values. The lower inlet gas temperature was resulted in lesser NO conversion at the same inlet NO concentration and gas velocity. The light-off temperatures were up to 520 K and a sudden rise in NO conversion was from 550-605 K and decreasing onwards, generating working temperature window. NO conversion increased throughout the catalyst bed from the inlet and the conversion decreased as the gas velocity increased. Conclusion/Recommendations: Gas space velocity and gas temperature intake to the converter affected the NO conversion over the time and the axial distance from the catalyst bed inlet. The numerical results have summarily demonstrated a good approximation compared to experimental

  5. Preparation and catalytic properties of honeycomb catalyst for hydrogen isotope oxidation

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Honeycomb catalysts with good physical properties were prepared for detritiation. • The catalysts increase gas flow rate significantly without decreasing the conversion rate. • The catalysts were used at room temperature with high H2 conversion rate. • The confines of H2 concentration and flow rate for catalyst application were tested. - Abstract: The method of catalytic oxidation and adsorption is widely used for atmosphere detritiation. But traditional particle catalyst has large gas resistance, which limited the space velocity for detritiation. Honeycomb catalyst can enormously increase the gas handling capacity due to its low pressure drop and high dispersity of active ingredients, but has not been used in detritiation so far. A coating of alumina was deposited on the honeycomb substrate of cordierite using ultrasonic technology. By the method of excessive impregnating, noble metal (Pt or Pd) supported catalysts were prepared. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption/desorption (Brunauer–Emmet–Teller – BET method), scanning electron microscope (SEM) and laser particles sizer. The result shows that the alumina coatings are well distributed, well knitted and the specific surface area of honeycomb catalyst rises to about 20 m2/g. Catalytic activities were evaluated by H2 conversion rate in gas mixture (with different H2 concentration and various flow rates). The results indicated that all catalysts exhibited excellent catalytic performance for H2 oxidation; the conversions of hydrogen were 100% at room temperature when the gas space velocity was up to 6 × 105 h−1

  6. A Novel Supramolecular Assembly Film of Porphyrin Bound DNA: Characterization and Catalytic Behaviors Towards Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Osamu Ikeda

    2005-04-01

    Full Text Available A stable Fe(4-TMPyP-DNA-PADDA (FePyDP film was characterized onpyrolytic graphite electrode (PGE or an indium-tin oxide (ITO electrode through thesupramolecular interaction between water-soluble iron porphyrin (Fe(4-TMPyP and DNAtemplate, where PADDA (poly(acrylamide-co-diallyldimethylammonium chloride isemployed as a co-immobilizing polymer. Cyclic voltammetry of FePyDP film showed a pairof reversible FeIII/FeII redox peaks and an irreversible FeIV/FeIII peak at –0.13 V and 0.89vs. Ag|AgCl in pH 7.4 PBS, respectively. An excellent catalytic reduction of NO wasdisplayed at –0.61 V vs. Ag|AgCl at a FePyDP film modified electrode.Chronoamperometric experiments demonstrated a rapid response to the reduction of NOwith a linear range from 0.1 to 90 μM and a detection limit of 30 nM at a signal-to-noiseratio of 3. On the other hand, it is the first time to apply high-valent iron porphyrin ascatalyst at modified electrode for NO catalytic oxidation at 0.89 vs. Ag|AgCl. The sensorshows a high selectivity of some endogenous electroactive substances in biological systems.The mechanism of response of the sensors to NO is preliminary studied.

  7. Solid-oxide fuel cell operated on in situ catalytic decomposition products of liquid hydrazine

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Hongxia; Ran, Ran; Zhou, Wei; Shao, Zongping; Jin, Wanqin; Xu, Nanping [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, No. 5 Xing Mofan Road, Nanjing, JiangSu 210009 (China); Ahn, Jeongmin [School of Mechanical and Materials Engineering, Washington State University, Sloan 217, Pullman, WA 99164-2920 (United States)

    2008-03-01

    Hydrazine was examined as a fuel for a solid-oxide fuel cell (SOFC) that employed a typical nickel-based anode. An in situ catalytic decomposition of hydrazine at liquid state under room temperature and ambient pressure before introducing to the fuel cell was developed by applying a Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF) oxide catalyst. Catalytic testing demonstrated that liquid N{sub 2}H{sub 4} can be decomposed to gaseous NH{sub 3} and H{sub 2} at a favorable rate and at a temperature as low as 20 C and H{sub 2} selectivity reaching values as high as 10% at 60 C. Comparable fuel cell performance was observed using either the in situ decomposition products of hydrazine or pure hydrogen as fuel. A peak power density of {proportional_to}850 mW cm{sup -2} at 900 C was obtained with a typical fuel cell composed of scandia-stabilized zirconia and La{sub 0.8}Sr{sub 0.2}MnO{sub 3} cathode. The high energy and power density, easy storage and simplicity in fuel delivery make it highly attractive for portable applications. (author)

  8. Activated carbon and tungsten oxide supported on activated carbon catalysts for toluene catalytic combustion.

    Science.gov (United States)

    Alvarez-Merino, M A; Ribeiro, M F; Silva, J M; Carrasco-Marín, F; Maldonado-Hódar, F J

    2004-09-01

    We have used activated carbon (AC) prepared from almond shells as a support for tungsten oxide to develop a series of WOx/AC catalysts for the catalytic combustion of toluene. We conducted the reaction between 300 and 350 degrees C, using a flow of 500 ppm of toluene in air and space velocity (GHSV) in the range 4000-7000 h(-1). Results show that AC used as a support is an appropriate material for removing toluene from dilute streams. By decreasing the GHSV and increasing the reaction temperature AC becomes a specific catalyst for the total toluene oxidation (SCO2 = 100%), but in less favorable conditions CO appears as reaction product and toluene-derivative compounds are retained inside the pores. WOx/AC catalysts are more selective to CO2 than AC due to the strong acidity of this oxide; this behavior improves with increased metal loading and reaction temperature and contact time. The catalytic performance depends on the nonstoichiometric tungsten oxide obtained during the pretreatment. In comparison with other supports the WOx/AC catalysts present, at low reaction temperatures, higher activity and selectivity than WO, supported on SiO2, TiO2, Al2O3, or Y zeolite. This is due to the hydrophobic character of the AC surface which prevents the adsorption of water produced from toluene combustion thus avoiding the deactivation of the active centers. However, the use of WOx/AC system is always restricted by its gasification temperature (around 400 degrees C), which limits the ability to increase the conversion values by increasing reaction temperatures. PMID:15461177

  9. Heterogeneous selective oxidation of formaldehyde over oxide catalysts. 1. Catalytic properties of H3PMo12O40 and K3PMoO12O40

    International Nuclear Information System (INIS)

    Catalytic properties of H3PMo12O40 and K3PMo12O40, dried at 120 deg C and calcinated at 420 deg C, were investigated in the reaction of heterogenous oxidation of formaldehyde in temperature range 120-180 deg C. It is shown that catalytic properties are determined by heat treatment conditions. Formic acid is the main product of formaldehyde oxidation on dried samples. Samples calcinated at 42 deg C are inactive in reaction of formaldehyde oxidation. It is shown that hydrated forms of H3PMo12O40 and K3PMo12O40 are effective in this reaction. (author)

  10. Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Ankur Bordoloi

    2014-01-01

    Full Text Available Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15 wt% and calcination temperatures of 673, 973, and 1073 K indicates that Co2+ is homogeneously distributed in the mesoporous alumina matrix. As a function of the Co loading, different phases are present comprising poorly crystalline alumina and mixed cobalt aluminum oxides of the spinel type. The mixed cobalt-aluminum oxides were applied as catalysts in CO oxidation and turned out to be highly active.

  11. Synthesis, characterization and photo catalytic studies of the composites by tantalum oxide and zinc oxide nanorods

    Science.gov (United States)

    Chennakesavulu, K.; Reddy, M. Madhusudhana; Reddy, G. Ramanjaneya; Rabel, A. M.; Brijitta, J.; Vinita, V.; Sasipraba, T.; Sreeramulu, J.

    2015-07-01

    In-situ synthesis of ZnO:Ta2O5 composites in basic medium by using tantalum chloride and zinc chloride as precursors. The prepared composites were characterized by Fourier Transform Infrared spectroscopy (FTIR), confocal Raman spectroscopy, diffuse reflectance UV-Vis spectrophotometer (DRS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, N2-sorption isotherms, Thermo Gravimetric Analysis (TGA), High Resolution Transmission Electron Microscope (HRTEM), X-ray Photoelectron Spectroscopy (XPS), and Field Emission Scanning Electron Microscopy (FESEM/EDS). The composite materials were used as photocatalyst in the degradation Rhodamine-B (RhB) dye under visible light irradiation. The catalytic activity and removal percentage of the dye was determined by the spectrophotometric method. This indicates the percentage of degradation was more for the ZnO:Ta2O5 composites. The kinetic parameter obeys pseudo-first order reaction. It may be due to fixed amount the catalysts and concentration of dye solution. The catalytic activity of the recycled ZnO:Ta2O5 catalyst was compared with fresh catalyst.

  12. Influence of thermal treatments on the basic and catalytic properties of Mg,Al-mixed oxides derived from hydrotalcites

    Directory of Open Access Journals (Sweden)

    R. Bastiani

    2004-06-01

    Full Text Available This work studied the influence of calcination conditions on basic properties and catalytic performance of Mg,Al-mixed oxides derived from a hydrotalcite sample (Al/(Al+Mg=0.20. Various heating rates, calcination atmospheres and lengths of calcination at 723K were evaluated. TPD of CO2 and retroaldolization of diacetone alcohol (DAA were used to determine the basic properties of the mixed oxides. The basic site density determined by TPD of CO2 showed a better correlation with catalytic activity for acetone/citral aldol condensation than the relative basicity obtained from retroaldolization of DAA. Calcination atmosphere was the parameter that influenced most the basic and the catalytic properties of the Mg,Al-mixed oxides, with calcination under dry air being the best choice.

  13. Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    The cerium iron complex oxides oxygen carder was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carrier could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carriers were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carder: the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species (bulk lattice oxygen) that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction con-dition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

  14. Precipitation of antimony from the solution of sodium thioantimonite by air oxidation in the presence of catalytic agents

    Institute of Scientific and Technical Information of China (English)

    杨天足; 赖琼琳; 唐建军; 楚广

    2002-01-01

    The behavior of antimony oxidation in the solution of sodium thioantimonite was studied in the presence of catalytic agents. The catalytic effects of the respective addition of cupric sulfate, sodium tartrate, potassium permanganate, phenol, 1,2-dihydroxybenzene and their combination on the oxidation of sodium thioantimonite were investigated. A pilot test was carried out. The results show that the respective use of sodium tartrate, cupric sulfate, potassium permanganate, phenol and 1,2-dihydroxybenzene have little catalytic effect on the oxidation of sodium thioantimonite. However there exists obvious catalytic oxidation by the combination of 0.25 g/L 1,2-dihydroxybenzene, 0.5 g/L potassium permanganate and 1.0 g/L phenol. Moreover, high blast intensity, the increase of temperature and NaOH concentration favor the oxidation of antimony. The oxidation process of antimony has such advantages as quick reaction and low operation costs. The results of the pilot test are consistent with those of laboratory experiments.

  15. Iron-oxide-supported nanocarbon in lithium-ion batteries, medical, catalytic, and environmental applications.

    Science.gov (United States)

    Tuček, Jiří; Kemp, Kingsley Christian; Kim, Kwang Soo; Zbořil, Radek

    2014-08-26

    Owing to the three different orbital hybridizations carbon can adopt, the existence of various carbon nanoallotropes differing also in dimensionality has been already affirmed with other structures predicted and expected to emerge in the future. Despite numerous unique features and applications of 2D graphene, 1D carbon nanotubes, or 0D fullerenes, nanodiamonds, and carbon quantum dots, which have been already heavily explored, any of the existing carbon allotropes do not offer competitive magnetic properties. For challenging applications, carbon nanoallotropes are functionalized with magnetic species, especially of iron oxide nature, due to their interesting magnetic properties (superparamagnetism and strong magnetic response under external magnetic fields), easy availability, biocompatibility, and low cost. In addition, combination of iron oxides (magnetite, maghemite, hematite) and carbon nanostructures brings enhanced electrochemical performance and (photo)catalytic capability due to synergetic and cooperative effects. This work aims at reviewing these advanced applications of iron-oxide-supported nanocarbon composites where iron oxides play a diverse role. Various architectures of carbon/iron oxide nanocomposites, their synthetic procedures, physicochemical properties, and applications are discussed in details. A special attention is devoted to hybrids of carbon nanotubes and rare forms (mesoporous carbon, nanofoam) with magnetic iron oxide carriers for advanced environmental technologies. The review also covers the huge application potential of graphene/iron oxide nanocomposites in the field of energy storage, biomedicine, and remediation of environment. Among various discussed medical applications, magnetic composites of zero-dimensional fullerenes and carbon dots are emphasized as promising candidates for complex theranostics and dual magneto-fluorescence imaging. PMID:25000534

  16. Electrochemical sensing chemical oxygen demand based on the catalytic activity of cobalt oxide film

    International Nuclear Information System (INIS)

    Highlights: ► A novel electrochemical sensor was developed for COD using cobalt oxide film. ► It exhibited high sensitivity, rapid response, good simplicity and practicability. ► It was used in numerous water samples, and accuracy was tested by standard method. - Abstract: Cobalt oxide sensing film was in situ prepared on glassy carbon electrode surface via constant potential oxidation. Controlling at 0.8 V in NaOH solution, the high-valence cobalt catalytically oxidized the reduced compounds, decreasing its surface amount and current signal. The current decline was used as the response signal of chemical oxygen demand (COD) because COD represents the summation of reduced compounds in water. The surface morphology and electrocatalytic activity of cobalt oxide were readily tuned by variation of deposition potential, time, medium and Co2+ concentration. As confirmed from the atomic force microscopy measurements, the cobalt oxide film, that prepared at 1.3 V for 40 s in pH 4.6 acetate buffer containing 10 mM Co(NO3)2, possesses large surface roughness and numerous three-dimensional structures. Electrochemical tests indicated that the prepared cobalt oxide exhibited high electrocatalytic activity to the reduced compounds, accompanied with strong COD signal enhancement. As a result, a novel electrochemical sensor with high sensitivity, rapid response and operational simplicity was developed for COD. The detection limit was as low as 1.1 mg L−1. The analytical application was studied using a large number of lake water samples, and the accuracy was tested by standard method.

  17. Mechanism of catalytic action of oxide systems in reactions of aldehyde oxidation to carboxylic acids

    International Nuclear Information System (INIS)

    Mechanism of selective action of oxide catalysts (on the base of V2O4, MoO3) of aldehyde oxidation to acids is considered, reaction acrolein oxidation to acrylic acid is taken as an example. Multistage mechanism of the process is established; it involves consequent transformation of coordination-bonded aldehyde into carbonyl-bonded aldehyde and symmetric carboxylate. Principles of active surface construction are formulated, they take into account the activity of stabilization center of concrete intermediate compound and bond energy of oxygen with surface. (author)

  18. THE EFFECT OF SEVERAL NON-OXIDIZING BIOCIDES ON FINE PAPER WET-END CHEMISTRY

    OpenAIRE

    Patrick Huber; Bruno Carré; Elisa Zeno

    2010-01-01

    Biocide programs have become necessary in most fine paper manufacturing circuits, as drastic reduction of fresh water consumption in the industry enhances microbial development. Depending on their chemical nature, biocides may interfere with typical wet-end chemistry additives and furnish. A reference wet-end chemistry was set (including fixing aid, dry strength aid, sizing agent, and retention system), then biocides were added to the furnish (bleached virgin fibres + mineral filler) prior to...

  19. A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II

    Science.gov (United States)

    Schulze, Marcus; Kunz, Valentin; Frischmann, Peter D.; Würthner, Frank

    2016-06-01

    Mimicking the ingenuity of nature and exploiting the billions of years over which natural selection has developed numerous effective biochemical conversions is one of the most successful strategies in a chemist's toolbox. However, an inability to replicate the elegance and efficiency of the oxygen-evolving complex of photosystem II (OEC-PSII) in its oxidation of water into O2 is a significant bottleneck in the development of a closed-loop sustainable energy cycle. Here, we present an artificial metallosupramolecular macrocycle that gathers three Ru(bda) centres (bda = 2,2‧-bipyridine-6,6‧-dicarboxylic acid) that catalyses water oxidation. The macrocyclic architecture accelerates the rate of water oxidation via a water nucleophilic attack mechanism, similar to the mechanism exhibited by OEC-PSII, and reaches remarkable catalytic turnover frequencies >100 s–1. Photo-driven water oxidation yields outstanding activity, even in the nM concentration regime, with a turnover number of >1,255 and turnover frequency of >13.1 s–1.

  20. Growth and morphology of carbon nanostructures on nickel oxide nanoparticles in catalytic chemical vapor deposition

    Science.gov (United States)

    Jana, M.; Sil, A.; Ray, S.

    2014-07-01

    The present study explores the conditions favorable for the growth of cylindrical carbon nanostructures such as multi-walled carbon nanotube (MWCNT) and carbon nanofiber by catalytic chemical vapor deposition (CCVD) method using nickel oxide-based catalyst nanoparticles of different average sizes as well as different levels of doping by copper oxide. The role of doping and the average size have been related to the observed melting behavior of nanoparticles of nickel oxide by thermal and diffraction analysis, and the importance of melting has been highlighted in the context of growth of cylindrical nanostructures. In the reducing environment prevailing in the CCVD chamber due to decomposition of flowing acetylene gas at elevated temperature, there is extensive reduction of oxide nanoparticles. Lack of melting and faster flow of carbon-bearing gases favor the formation of a carbon deposit cover over the catalyst nanoparticles giving rise to the formation of nanobeads. Melting allows rapid diffusion of carbon from the surface to inside catalyst particles, and reduced flow of gas lowers the rate of carbon deposit, both creating conditions favorable for the formation of cylindrical nanostructures, which grows around the catalyst particles. Smaller particle size and lower doping favor growth of MWCNT, while growth of fiber is commonly observed on larger particles having relatively higher level of doping.

  1. A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II.

    Science.gov (United States)

    Schulze, Marcus; Kunz, Valentin; Frischmann, Peter D; Würthner, Frank

    2016-06-01

    Mimicking the ingenuity of nature and exploiting the billions of years over which natural selection has developed numerous effective biochemical conversions is one of the most successful strategies in a chemist's toolbox. However, an inability to replicate the elegance and efficiency of the oxygen-evolving complex of photosystem II (OEC-PSII) in its oxidation of water into O2 is a significant bottleneck in the development of a closed-loop sustainable energy cycle. Here, we present an artificial metallosupramolecular macrocycle that gathers three Ru(bda) centres (bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) that catalyses water oxidation. The macrocyclic architecture accelerates the rate of water oxidation via a water nucleophilic attack mechanism, similar to the mechanism exhibited by OEC-PSII, and reaches remarkable catalytic turnover frequencies >100 s(-1). Photo-driven water oxidation yields outstanding activity, even in the nM concentration regime, with a turnover number of >1,255 and turnover frequency of >13.1 s(-1). PMID:27219702

  2. Wet Oxidation of Crude Manure and Manure Fibers: Substrate Characteristics Influencing the Pretreatment Efficiency for Increasing the Biogas Yield of Manure

    DEFF Research Database (Denmark)

    Uellendahl, Hinrich; Mladenovska, Zuzana; Ahring, Birgitte Kiær

    2007-01-01

    The biogas yield of manure is typically lower than 25 m3/t due to its low dry matter content and its high ratio of lignocellulosic fibers that are recalcitrant towards anaerobic digestion. A new pre-treatment method – wet oxidation – has been tested for disruption of the lignocellulosic fiber...... structure with subsequent higher degradation efficiencies and methane yields. A screening of crude manure and the separated fiber fraction shows that wet oxidation is more adequate for treatment of high concentrated solid fraction than for crude manure and an increase of 35% in biogas yield can be gained...... from wet oxidation of digested fibers. The wet oxidation treatment of the manure fiber fraction has to be carefully adjusted in order to achieve the highest increase in biogas yield for the manure fiber fraction under low production of inhibiting compounds and low losses of valuable organic matter....

  3. Functionalization to control microstructural, optical, electronic and wetting properties of metal oxide surfaces

    Science.gov (United States)

    Singh, Jagdeep

    This thesis focuses on engineering the surface chemistry of oxide surfaces in order to control their microstructural, optical, electronic and wetting properties. Several different types of experiments have been performed to tailor the properties of silicon oxide, titanium dioxide, and zinc oxide surfaces. Applications of this work include organic electronics, sensors and nanomanufacturing. Adsorption of 3-mercaptopropyltrimethoxysilane (MPS) on hydroxylated silicon oxide substrates by immersion in MPS solution or exposure to MPS vapor has been compared using X-ray photoelectron spectroscopy (XPS). To aid the interpretation, MPS has also been cryogenically condensed in ultrahigh vacuum (UHV) onto gold surfaces. Condensation of MPS vapor on gold in the absence of water does not result in MPS polymerization, as evidenced by multilayer desorption upon warming to room temperature. The C1s XPS spectrum has been used to infer the relative abundance of methoxy groups. Vapor-deposition on hydroxylated silicon oxide leads to an unpolymerized MPS monolayer consisting of molecules with two methoxy groups. UV induced hydrophilicity of titanium dioxide surfaces could possibly be used to provide a means of registration and alignment in high-rate nanomanufacturing applications or to induce transfer of nanoelements. In order to understand the nature and magnitude of intermolecular forces, force-distance curves have been measured on TiO2. Toward the goal of possibly using light to induce nanoparticle transfer, force curves have been recorded using an SiO2 colloidal probe before and after irradiating the TiO 2 surface with UV light. In order to eliminate the effects of capillary forces, the relative humidity has been kept below 1% by flowing either N 2 or N2/O2 (1:1) into the AFM chamber. In a dry nitrogen environment, no difference is observed in adhesive forces measured with and without UV exposure. Gold-coated atomic force microscope (AFM) tips functionalized with amine-, hydroxyl

  4. Role of iron oxide catalysts in selective catalytic reduction of NOx and soot from vehicular emission

    International Nuclear Information System (INIS)

    This study deals with Iron containing catalysts i.e Iron oxide Fe/sub 2/O/sub 3/) Iron potassium oxide Fe/sub 1.9/K/sub 0.1/O/sub 3/, copper iron oxide Cu/sub 0.9/K/sub 0.1/, Fe/sub 2/O/sub 3/, nickel iron oxide Ni Fe/sub 2/O/sub 4/, and Nickel potassium iron oxide Ni/sub 0.95/K/sub 0.05/ Fe/sub 2/O/sub 4/ catalyst were synthesized by using PVA technique. By X-ray Diffraction technique these catalysts were characterized to ensure the formation of crystalline structure. Energy Dispersive X-rays analysis (EDX) was used for the confirmation of presence of different metals and Scanning Electron Microscopy (SEM) for Surface Morphology. Then the catalytic investigations of the prepared catalyst were carried out for their activity measurement toward simultaneous conversion of NOx and Soot from an engine exhaust. Some Iron containing oxide catalysts were partially modified by alkali metal potassium and were used for NOx -Soot reaction in a model exhaust gas. Fe/sub 1.9 K /sub 0.1/O/sub 3/ show high catalytic performance for N/sub 2/ formation in the prepared catalyst. Further studies have shown that Fe/sub 1.9/ K/sub 0.1/ O/sub 3/ was deactivated in a substantial way after about 20 Temperature. Temperature Programmed Reaction (TPR) experiments due to agglomeration of the promoter potassium. Experiments carried out over the aged Fe/sub 1.9/K/sub 0.1/O/sub 3/ catalyst have shown that NOx-soot reaction was suppressed at higher oxygen concentration, since O/sub 2/-soot conversion was kindly favored. More over nitrite species formed at the catalyst surface might play an important role in NOx-soot conversion. (author)

  5. Thermal catalytic oxidation of octachloronaphthalene over anatase TiO2 nanomaterial and its hypothesized mechanism

    Science.gov (United States)

    Su, Guijin; Li, Qianqian; Lu, Huijie; Zhang, Lixia; Huang, Linyan; Yan, Li; Zheng, Minghui

    2015-12-01

    As an environmentally-green technology, thermal catalytic oxidation of octachloronaphthalene (CN-75) over anatase TiO2 nanomaterials was investigated at 300 °C. A wide range of oxidation intermediates, which were investigated using various techniques, could be of three types: naphthalene-ring, single-benzene-ring, and completely ring-opened products. Reactive oxygen species on anatase TiO2 surface, such as O2-• and O2-, contributed to oxidative degradation. Based on these findings, a novel oxidation degradation mechanism was proposed. The reaction at (101) surface of anatase TiO2 was used as a model. The naphthalene-ring oxidative products with chloronaphthols and hydroxyl-pentachloronaphthalene-dione, could be formed via attacking the carbon of naphthalene ring at one or more positions by nucleophilic O2-. Lateral cleavage of the naphthalene ring at different C1-C10 and C4-C9, C1-C2 and C4-C9, C1-C2 or and C3-C4 bond positions by electrophilic O2-• could occur. This will lead to the formation of tetrachlorophenol, tetrachloro-benzoic acid, tetrachloro-phthalaldehyde, and tetrachloro-acrolein-benzoic acid, partially with further transformation into tetrachlorobenzene-dihydrodiol and tetrachloro-salicylic acid. Unexpectedly, the symmetric half section of CN-75 could be completely remained with generating the intricate oxidative intermediates characteristically containing tetrachlorobenzene structure. Complete cleavage of naphthalene ring could produce the ring-opened products, such as formic and acetic acids.

  6. Electronic interface properties of silicon substrates after ozone based wet-chemical oxidation studied by SPV measurements

    International Nuclear Information System (INIS)

    The preparation of ultra-thin oxide layers on mono-crystalline silicon substrate surfaces with ozone dissolved in ultra pure water at ambient temperature was investigated as a low cost alternative to current wet-chemical cleaning and passivation processes in solar cell manufacturing. Surface photovoltage technique was applied as fast, nondestructive, and surface sensitive method, to provide detailed information about the influence of oxidation rate and substrate surface morphology on electronic properties of the oxidised silicon interfaces and subsequently prepared hydrogen terminated surfaces. Sequences of wet-chemical oxidation in ozone containing ultra pure water and subsequent oxide removal in diluted hydrofluoric acid solution could be utilised to prepare hydrophobic substrates, which are predominantly required as starting point for layer deposition and contact formation. On so prepared hydrogen-terminated substrates values of interface state densities Dit,min ≈ 5 × 1011 eV-1 cm-2 could be achieved, comparable to values obtained on the same substrates by the standard RCA process followed by HF dip.

  7. Electronic interface properties of silicon substrates after ozone based wet-chemical oxidation studied by SPV measurements

    Science.gov (United States)

    Angermann, Heike; Wolke, Klaus; Gottschalk, Christiane; Moldovan, Ana; Roczen, Maurizio; Fittkau, Jens; Zimmer, Martin; Rentsch, Jochen

    2012-08-01

    The preparation of ultra-thin oxide layers on mono-crystalline silicon substrate surfaces with ozone dissolved in ultra pure water at ambient temperature was investigated as a low cost alternative to current wet-chemical cleaning and passivation processes in solar cell manufacturing. Surface photovoltage technique was applied as fast, nondestructive, and surface sensitive method, to provide detailed information about the influence of oxidation rate and substrate surface morphology on electronic properties of the oxidised silicon interfaces and subsequently prepared hydrogen terminated surfaces. Sequences of wet-chemical oxidation in ozone containing ultra pure water and subsequent oxide removal in diluted hydrofluoric acid solution could be utilised to prepare hydrophobic substrates, which are predominantly required as starting point for layer deposition and contact formation. On so prepared hydrogen-terminated substrates values of interface state densities Dit,min ≈ 5 × 1011 eV-1 cm-2 could be achieved, comparable to values obtained on the same substrates by the standard RCA process followed by HF dip.

  8. Investigation of the Cu-Zr-Y oxides activity in the carbon black catalytic oxidation by differential thermal analysis and temperature programmed reduction

    International Nuclear Information System (INIS)

    Different copper/zirconium-yttrium catalysts have been tested in carbon black oxidation reaction. Supported mainly on differential thermal analysis and temperature programmed reduction, two different mechanisms have been proposed to explain the catalytic results. In the absence of copper, it has been shown that Zr3+ ions and associated anionic vacancies are responsible to the catalytic enhancement observed in the mixed oxides, oxygen species being activated on these sites. Among mixed zirconia-yttria solids, ZrO2-5 mol%Y2O3 is the most active catalyst. Copper impregnation on these oxides leads to the formation of different copper species. Small particles of CuO in low interaction with the support, induce a catalytic improvement due to the highest reducibility of these species. Moreover, in order to be more efficient, CuO species should have some interactions with the support, since impregnated samples are more active than the simple mechanical mixtures

  9. Trends in reactivity of oxides:applied to catalytic oxidation of hydrogen halides

    OpenAIRE

    Toftelund, Anja; Rossmeisl, Jan; Bligaard, Thomas

    2012-01-01

    Resultaterne i denne afhandling er baseret på beregninger udført vha. tæthedsfunktionalteori.Den katalystiske aktivitet af oxider og andre sammensatte materialer er blevet undersøgt. Det konstateres, at adsorbtionsenergien af molekylerne NH2, NH, OH og SH på overfladerne af overgangsmetalnitrid, -oxid og -sulfid skalerer lineært med adsorbtionsenergien af det centrale N, O og S atom. Det er også fundet at de følger samme tendens som adsorbtion af de samme molekyler på overgangsmetaller. Den s...

  10. Improved Aeration Process - Catalytic Role Of The Iron Oxides In Arsenic Oxidation And Coprecipitation

    DEFF Research Database (Denmark)

    Kowalski, Krysztof; Søgaard, Erik Gydesen

    2013-01-01

    improved aeration process that can also help in developing better arsenic removal treatment. The results present advantages of arsenic oxidation in an aeration process in the presence of ferrihydrite surface that have been shown to adsorb arsenic simultaneously to its oxidation. The presence of...... aeration. Moreover, it was found that the adsorption rate was limited by an excess of dissolved iron, due to competition between arsenic and iron compounds for adsorption sites on iron oxyhydroxide surface. The results were obtained both in lab and pilot scale experiments, which enabled to illustrate...

  11. Oxides Catalysts of Rare Earth and Transient Metal for Catalytic Oxidation of Benzene

    Institute of Scientific and Technical Information of China (English)

    Liang Kun; Li Rong; Chen Jianjun; Ma Jiantai

    2004-01-01

    The catalysts of CeO2 and the mixture of CeO2 and CuO were prepared, and the activities of these catalysts for completely oxidizing benzene were studied.The results show that the optimal proportion of CeO2/CuO is 6: 4.The highest temperature at which benzene was completely oxidized on these catalysts at different airspeed was measured.Compared these catalysts with the noble metal used, our catalysts had superiority in the resources and the industrial cost besides good activities.

  12. Catalytic processes during preferential oxidation of CO in H 2-rich streams over catalysts based on copper-ceria

    Science.gov (United States)

    Gamarra, D.; Hornés, A.; Koppány, Zs.; Schay, Z.; Munuera, G.; Soria, J.; Martínez-Arias, A.

    Nanostructured catalysts based on combinations between oxidised copper and cerium entities prepared by two different methods (impregnation of ceria and coprecipitation of the two components within reverse microemulsions) have been examined with respect to their catalytic performance for preferential oxidation of CO in a H 2-rich stream (CO-PROX). Correlations between their catalytic and redox properties are established on the basis of parallel analyses of temperature programmed reduction results employing both H 2 and CO as reactants as well as by XPS. Although general catalytic trends can be directly correlated with the redox properties observed upon separate interactions with each of the two reductants (CO and H 2), the existence of interferences between both reductants must be considered to complete details for such activity/redox correlation. Differences in the nature of the active oxidised copper-cerium contacts present in each case determine the catalytic properties of these systems for the CO-PROX process.

  13. Synthesis, Characterization and Shape-Dependent Catalytic CO Oxidation Performance of Ruthenium Oxide Nanomaterials: Influence of Polymer Surfactant

    Directory of Open Access Journals (Sweden)

    Antony Ananth

    2015-08-01

    Full Text Available Ruthenium oxide nano-catalysts supported on mesoporous γ-Al2O3 have been prepared by co-precipitation method and tested for CO oxidation. The effect of polyethylene glycol (PEG on the properties of the catalyst was studied. Addition of the PEG surfactant acted as a stabilizer and induced a change in the morphology of ruthenium oxide from spherical nanoparticles to one-dimensional nanorods. Total CO conversion was measured as a function of morphology at 175 °C and 200 °C with 1.0 wt.% loading for PEG-stabilized and un-stabilized catalysts, respectively. Conversion routinely increased with temperature but in each case, the PEG-stabilized catalyst exhibited a notably higher catalytic activity as compared to the un-stabilized equivalent. It can be assumed that the increase in the activity is due to the changes in porosity, shape and dispersion of the catalyst engendered by the use of PEG.

  14. Fabrication of Au–Pd nanoparticles/graphene oxide and their excellent catalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    He, Yongqiang, E-mail: heyongqiang@126.com [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Zhang, Nana; Zhang, Lei [School of Science, Tianjin University, Tianjin 300072 (China); Gong, Qiaojuan [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Yi, Maocong [School of Science, Tianjin University, Tianjin 300072 (China); Wang, Wei [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Qiu, Haixia, E-mail: qhx@tju.edu.cn [School of Science, Tianjin University, Tianjin 300072 (China); Gao, Jianping [School of Science, Tianjin University, Tianjin 300072 (China)

    2014-03-01

    Graphical abstract: - Highlights: • Au and Pd nanoparticles loaded on GO were fabricated without adding any reducing agents. • The Au–Pd NPs/GO were excellent catalysts for the reduction of 4-nitrophenol. • The Au–Pd NPs/GO showed superior catalytic activity for the Suzuki reaction. • The Au–Pd NPs/GO exhibit good reusability. - Abstract: A simple method to fabricate clean Au–Pd nanoparticles on graphene oxide (Au–Pd NPs/GO) without using any reducing agent or surfactant has been developed. GO simultaneously reduced the Au and Pd precursors to form a stable suspension of the Au–Pd NPs/GO. The nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and inductively coupled plasma. The Au–Pd NPs/GO exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol and for the Suzuki–Miyaura coupling reaction of chlorobenzene and phenylboronic acid in aqueous media.

  15. Fabrication of Au–Pd nanoparticles/graphene oxide and their excellent catalytic performance

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Au and Pd nanoparticles loaded on GO were fabricated without adding any reducing agents. • The Au–Pd NPs/GO were excellent catalysts for the reduction of 4-nitrophenol. • The Au–Pd NPs/GO showed superior catalytic activity for the Suzuki reaction. • The Au–Pd NPs/GO exhibit good reusability. - Abstract: A simple method to fabricate clean Au–Pd nanoparticles on graphene oxide (Au–Pd NPs/GO) without using any reducing agent or surfactant has been developed. GO simultaneously reduced the Au and Pd precursors to form a stable suspension of the Au–Pd NPs/GO. The nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and inductively coupled plasma. The Au–Pd NPs/GO exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol and for the Suzuki–Miyaura coupling reaction of chlorobenzene and phenylboronic acid in aqueous media

  16. Fabrication of highly catalytic silver nanoclusters/graphene oxide nanocomposite as nanotag for sensitive electrochemical immunoassay.

    Science.gov (United States)

    Wang, Jiamian; Wang, Xiuyun; Wu, Shuo; Song, Jie; Zhao, Yanqiu; Ge, Yanqiu; Meng, Changgong

    2016-02-01

    Silver nanoclusters and graphene oxide nanocomposite (AgNCs/GRO) is synthesized and functionalized with detection antibody for highly sensitive electrochemical sensing of carcinoembryonic antigen (CEA), a model tumor marker involved in many cancers. AgNCs with large surface area and abundant amount of low-coordinated sites are synthesized with DNA as template and exhibit high catalytic activity towards the electrochemical reduction of H2O2. GRO is employed to assemble with AgNCs because it has large specific surface area, super electronic conductivity and strong π-π stacking interaction with the hydrophobic bases of DNA, which can further improve the catalytic ability of the AgNCs. Using AgNCs/GRO as signal amplification tag, an enzyme-free electrochemical immunosensing protocol is designed for the highly sensitive detection of CEA on the capture antibody functionalized immunosensing interface. Under optimal conditions, the designed immunosensor exhibits a wide linear range from 0.1 pg mL(-1) to 100 ng mL(-1) and a low limit of detection of 0.037 pg mL(-1). Practical sample analysis reveals the sensor has good accuracy and reproducibility, indicating the great application prospective of the AgNCs/GRO in fabricating highly sensitive immunosensors, which can be extended to the detection of various kinds of low abundance disease related proteins. PMID:26772127

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

    Directory of Open Access Journals (Sweden)

    ZELJKO B. GRBAVCIC

    2004-12-01

    Full Text Available The removal of ethylene oxide (EtO in a combined system adsorber/desorber/catalytic reactor has been investigated. The combined system was a modified draft tube spouted bed reactor loaded with Pt/Al2O3 catalyst. The annular region was divided into two sectons, the “hot” section contained about 7 % of catalyst and it behaved as a desorber and catalytic incinerator, while the “cold” section, with the rest of the catalyst, behaved as a sorber. The catalyst particles were circulated between the two sections by use of a draft tube riser. The Computational Fluid Dynamics (CFD program package FLUENT was used for simulations of the operation of the combined system. In addition, a one-dimensional numerical model for the operation of the packed bed reactor was compared with the corresponding FLUENT calculations. The results of the FLUENT simulations are in very good agreement with the experimental observations, as well as with the results of the one-dimensional numerical simulations.

  18. Characterization of microstructure and catalytic of cerium oxide obtained by colloidal solution

    International Nuclear Information System (INIS)

    This study investigated to obtain particles of cerium oxide, for use as catalysts for the combustion of methane using the technique of through polymeric colloidal solution. Obtaining the colloidal system is based on hydrolysis of salts such as cerium acetylacetonate, cerium nitrate in the presence of additives such as polyvinylbutyral (PVB), polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA), at concentrations of 5, 10 and 15% in aqueous or alcoholic medium. These solutions containing ions of interest were subjected to a heat treatment at 650° C for 30 minutes, with heating rate of 2 ° C/ min. After heat treatment, the fibers were characterized according to their morphology, surface area, crystallinity, weight loss and catalytic activity. Samples obtained from cerium acetylacetonate were more reactive than the cerium nitrate to the combustion of methane, as showed greater conversions and higher temperatures reached during the process, which is of utmost importance since the combustion catalytic methane is used for generating thermal energy. After the reaction with methane, the samples underwent significant change in surface area, probably due to the intensity of combustion reactions of the nitrate and the generation of heat involved in this reaction, which gave rise to coarse particles. During the combustion process using the obtained from particles of cerium acetylacetonate, there was the release of large quantities of nitrogen compared to the results of assays with the particles obtained with cerium nitrate. (author)

  19. Identification of Subnanometric Ag Species, Their Interaction with Supports and Role in Catalytic CO Oxidation

    Directory of Open Access Journals (Sweden)

    Yulia Kotolevich

    2016-04-01

    Full Text Available The nature and size of the real active species of nanoparticulated metal supported catalysts is still an unresolved question. The technique of choice to measure particle sizes at the nanoscale, HRTEM, has a practical limit of 1 nm. This work is aimed to identify the catalytic role of subnanometer species and methods to detect and characterize them. In this frame, we investigated the sensitivity to redox pretreatments of Ag/Fe/TiO2, Ag/Mg/TiO2 and Ag/Ce/TiO2 catalysts in CO oxidation. The joint application of HRTEM, SR-XRD, DRS, XPS, EXAFS and XANES methods indicated that most of the silver in all samples is in the form of Ag species with size <1 nm. The differences in catalytic properties and sensitivity to pretreatments, observed for the studied Ag catalysts, could not be explained taking into account only the Ag particles whose size distribution is measured by HRTEM, but may be explained by the presence of the subnanometer Ag species, undetectable by HRTEM, and their interaction with supports. This result highlights their role as active species and the need to take them into account to understand integrally the catalysis by supported nanometals.

  20. Synthesis and catalytic properties of microemulsion-derived cerium oxide nanoparticles

    Science.gov (United States)

    Kockrick, Emanuel; Schrage, Christian; Grigas, Anett; Geiger, Dorin; Kaskel, Stefan

    2008-07-01

    The synthesis of cerium dioxide nanoparticles using an inverse microemulsion technique and precipitation method was investigated. Cerium hydroxide nanoparticles were synthesized by adding diluted ammonia to n-heptane-surfactant-cerium nitrate system. The micelle and particle size in the range of 5-12 nm were controlled by varying the molar water to surfactant ratio and analyzed by dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM). Cerium hydroxide nanoparticles were isolated and subsequently treated at 100-600 °C to obtain nanoscale ceria. Crystallite sizes of cerium dioxide in the range of 6-16 nm were estimated by Scherrer analysis by X-ray diffraction (XRD) and HRTEM. The catalytic activity of particles annealed at 400 and 600 °C in soot combustion reactions was characterized by temperature-programmed oxidation (TPO) indicating a size-dependant activity. Crystallite sizes and catalytic stability of elevated ceria systems were tested in second combustion cycles.

  1. Catalytic oxidation of xanthine by the nanostructured poly(aniline-co-2,4-diaminophenol)

    International Nuclear Information System (INIS)

    Poly(aniline-co-2,4-diaminophenol) (PADAP) was synthesized in a solution containing aniline, 2,4-diaminophenol (DAP) and sulfuric acid, using potentiostatic method. The image of a PADAP film is constructed of spherical particles with an average diameter of 50 nm, which was examined by both scanning electron microscope (SEM) and atomic force microscopy (AFM). The nanostructured PADAP can catalyze xanthine oxidation under a less positive potential of 0.31 V (vs. SCE), which was proved by cyclic voltammetry and amperometric method. The PADAP electrode has a very fast response for the determination of xanthine. The response current of the PADAP electrode increases with increasing xanthine concentration and applied potential. The catalytic mechanism for the oxidation of xanthine on the nanostructured PADAP electrode is similar to that of xanthine oxidase-catalyzed reaction. Experimental evidence for the electrocatalytic mechanism of xanthine oxidation on a PADAP electrode was demonstrated via measurements of the open-circuit potential and the in situ chemical-ESR spectra of PADAP in the solutions without and with xanthine, respectively.

  2. Removal of radionuclides from partitioning waste solutions by adsorption and catalytic oxidation methods

    Energy Technology Data Exchange (ETDEWEB)

    Yamagishi, Isao; Yamaguchi, Isoo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kubota, Masumitsu [Research Organization for Information Science and Technology (RIST), Tokai, Ibaraki (Japan)

    2000-09-01

    Adsorption of radionuclides with inorganic ion exchangers and catalytic oxidation of a complexant were studied for the decontamination of waste solutions generated in past partitioning tests with high-level liquid waste. Granulated ferrocyanide and titanic acid were used for adsorption of Cs and Sr, respectively, from an alkaline solution resulting from direct neutralization of an acidic waste solution. Both Na and Ba inhibited adsorption of Sr but Na did not that of Cs. These exchangers adsorbed Cs and Sr at low concentration with distribution coefficients of more than 10{sup 4}ml/g from 2M Na solution of pH11. Overall decontamination factors (DFs) of Cs and total {beta} nuclides exceeded 10{sup 5} and 10{sup 3}, respectively, at the neutralization-adsorption step of actual waste solutions free from a complexant. The DF of total {alpha} nuclides was less than 10{sup 3} for a waste solution containing diethylenetriaminepentaacetic acid (DTPA). DTPA was rapidly oxidized by nitric acid in the presence of a platinum catalyst, and radionuclides were removed as precipitates by neutralization of the resultant solution. The DF of {alpha} nuclides increased to 8x10{sup 4} by addition of the oxidation step. The DFs of Sb and Co were quite low through the adsorption step. A synthesized Ti-base exchanger (PTC) could remove Sb with the DF of more than 4x10{sup 3}. (author)

  3. Single-Site Palladium(II) Catalyst for Oxidative Heck Reaction: Catalytic Performance and Kinetic Investigations

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hui; Li, Mengyang; Zhang, Guanghui; Gallagher, James R.; Huang, Zhiliang; Sun, Yu; Luo, Zhong; Chen, Hongzhong; Miller, Jeffrey T.; Zou, Ruqiang; Lei, Aiwen; Zhao, Yanli

    2015-01-01

    ABSTRACT: The development of organometallic single-site catalysts (SSCs) has inspired the designs of new heterogeneous catalysts with high efficiency. Nevertheless, the application of SSCs in certain modern organic reactions, such as C-C bond formation reactions, has still been less investigated. In this study, a single-site Pd(II) catalyst was developed, where 2,2'-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd(II) complex. The overall performance of the single-site Pd(II) catalyst in the oxidative Heck reaction was then investigated. The investigation results show that the catalyst displays over 99% selectivity for the product formation with high reaction yield. Kinetic profiles further confirm its high catalytic efficiency, showing that the rate constant is nearly 40 times higher than that for the free Pd(II) salt. X-ray absorption spectroscopy reveals that the catalyst has remarkable lifetime and recyclability.

  4. Graphene oxide supported Au–Ag alloy nanoparticles with different shapes and their high catalytic activities

    International Nuclear Information System (INIS)

    A simple method was developed to fabricate Au–Ag nanoparticle/graphene oxide nanocomposites (Au–Ag/GO) by using simultaneous redox reactions between AgNO3, HAuCl4 and GO. The Au–Ag/GO was characterized by x-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive x-ray spectroscopy. The GO nanosheets acted as the reducing agent and the support for the Au–Ag alloy nanoparticles. In addition, Au–Ag alloy nanoparticles with different shapes including core–shell-like, dendrimer-like and flower-like were obtained by simply modifying the concentration of the reactants and the reaction temperature. With no reducing or stabilizing agents added, the Au–Ag/GO nanocomposites show superior catalytic performance for the reduction of 4-nitrophenol and for the aerobic homocoupling of phenylboronic acid. (paper)

  5. Dynamic\tmodelling of catalytic three-phase reactors for hydrogenation and oxidation processes

    Directory of Open Access Journals (Sweden)

    Salmi T.

    2000-01-01

    Full Text Available The dynamic modelling principles for typical catalytic three-phase reactors, batch autoclaves and fixed (trickle beds were described. The models consist of balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. Rate equations, transport models and mass balances were coupled to generalized heterogeneous models which were solved with respect to time and space with algorithms suitable for stiff differential equations. The aspects of numerical solution strategies were discussed and the procedure was illustrated with three case studies: hydrogenation of aromatics, hydrogenation of aldehydes and oxidation of ferrosulphate. The case studies revealed the importance of mass transfer resistance inside the catalyst pallets as well as the dynamics of the different phases being present in the reactor. Reliable three-phase reactor simulation and scale-up should be based on dynamic heterogeneous models.

  6. Catalytic and electrocatalytic oxidation of carbon monoxide on a Fe electrode in a solid electrolyte cell

    International Nuclear Information System (INIS)

    The catalytic oxidation of carbon monoxide on Fe catalyst was studied at 300-500C and atmospheric total pressure. The reaction was studied under both open- and closed-circuit operation in an yttria-stabilized zirconia solid electrolyte cell. The technique of Solid Electrolyte Potentiometry (SEP) was used to monitor the thermodynamic activity of oxygen adsorbed on the Fe electrode under open circuit. Kinetic and potentiometric measurements were combined in order to elucidate the reaction mechanism. The results are in agreement with a Langmuir-Hinselwood type of adsorption-reaction with two different adsorption sites for carbon monoxide and oxygen. Under closed circuit, the effect of electrochemical oxygen 'pumping' to the catalyst was examined. The operation of the cell was almost Faradaic as the rate enhancement factor (λ) values measured were close to unity

  7. Identification of Subnanometric Ag Species, Their Interaction with Supports and Role in Catalytic CO Oxidation.

    Science.gov (United States)

    Kotolevich, Yulia; Kolobova, Ekaterina; Khramov, Evgeniy; Cabrera Ortega, Jesús Efren; Farías, Mario H; Zubavichus, Yan; Zanella, Rodolfo; Mota-Morales, Josué D; Pestryakov, Alexey; Bogdanchikova, Nina; Cortés Corberán, Vicente

    2016-01-01

    The nature and size of the real active species of nanoparticulated metal supported catalysts is still an unresolved question. The technique of choice to measure particle sizes at the nanoscale, HRTEM, has a practical limit of 1 nm. This work is aimed to identify the catalytic role of subnanometer species and methods to detect and characterize them. In this frame, we investigated the sensitivity to redox pretreatments of Ag/Fe/TiO₂, Ag/Mg/TiO₂ and Ag/Ce/TiO₂ catalysts in CO oxidation. The joint application of HRTEM, SR-XRD, DRS, XPS, EXAFS and XANES methods indicated that most of the silver in all samples is in the form of Ag species with size nanometals. PMID:27110757

  8. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    Directory of Open Access Journals (Sweden)

    Kabljanac, Ž.

    2011-11-01

    Full Text Available This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comparison with designed capacity for one production line is shown in the Table 1. Shown is the effectiveness of selective catalytic reduction in the temperature range of the tail gas from 180 to 230 °C with direct application of liquid ammonia, without prior evaporation to gaseous state. The results of inlet and outlet concentrations of nitrous oxides in the tail gas of the nitric acid production process are shown in Figures 1 and 2. Figure 3 shows the temperature dependence of the selective catalytic reduction of nitrous oxides expressed as NO2in the tail gas of nitric acid production with the application of a constant mass flow of liquid ammonia of 13,0 kg h-1 and average inlet mass concentration of the nitrous oxides expressed as NO2of 800,0 mgm-3 during 100 % production capacity. The specially designed liquid-ammonia direct-dosing system along with the effective homogenization of the tail gas resulted in emission levels of nitrous oxides expressed as NO2 in tail gas ranging from 100,0 to 185,0 mg m-3. The applied low-temperature selective catalytic reduction of the nitrous oxides in the tail gases by direct use of liquid ammonia is shown in Figure 4. It is shown that low-temperature selective catalytic reduction with direct application of liquid ammonia opens a new opportunity in the reduction of nitrous oxide emissions during nitric acid production without the risk of dangerous ammonium nitrate occurring in the process of subsequent energy utilization of

  9. Catalytic combustion of soot over Ru-doped mixed oxides catalysts

    Institute of Scientific and Technical Information of China (English)

    LF Nascimento; RF Martins; OA Serra

    2014-01-01

    We employed modified substrates as outer heterogeneous catalysts to reduce the soot originating from the incomplete die-sel combustion. Here, we proposed that ceria (CeO2)-based catalysts could lower the temperature at which soot combustion occurred from 610 ºC to values included in the operation range of diesel exhausts (270-400 ºC). Here, we used the sol-gel method to synthesize catalysts based on mixed oxides (ZnO:CeO2) deposited on cordierite substrates, and modified by ruthenium nanoparticles. The presence of ZnO in these mixed oxides produced defects associated with oxygen vacancies, improving thermal stability, redox potential, sulfur resistance, and oxygen storage. We evaluated the morphological and structural properties of the material by X-ray diffraction (XRD), Brumauer-emmett-teller method (BET), temperature programmed reduction (H2-TPR), scanning electron micros-copy (SEM), and transmission electron microscopy (TEM). We investigated how the addition of Ru (0.5 wt.%) affected the catalytic activity of ZnO:CeO2 in terms of soot combustion. Thermogravimetric analysis (TG/DTA) revealed that presence of the catalyst de-creased the soot combustion temperature by 250 ºC, indicating that the oxygen species arose at low temperatures, which was the main reason for the high reactivity of the oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy (DRS) showed that the catalyst containing Ru on the mixed oxide-impregnated cordierite samples efficiently oxidized soot in a diesel stationary motor:soot emission decreased 80%.

  10. Oxidative destruction of biomolecules by gasoline engine exhaust products and detoxifying effects of the three-way catalytic converter.

    Science.gov (United States)

    Blaurock, B; Hippeli, S; Metz, N; Elstner, E F

    1992-01-01

    Aqueous solutions of engine exhaust condensation products were derived from cars powered by diesel or four-stroke gasoline engines (with and without three-way catalytic converter). The cars were operated on a static test platform. Samples of the different exhaust solutions accumulated in a Grimmer-type distillation trap (VDI 3872) during standard test programs (Federal Test Procedure) were incubated with important biomolecules. As indicators of reactive oxygen species or oxidative destruction, ascorbic acid, cysteine, glutathione, serum albumin, the enzymes glycerinaldehyde phosphate dehydrogenase and xanthine oxidase, and the oxygen free-radical indicator keto-methylthiobutyrate were used. During and after the incubations, oxygen activation (consumption) and oxidative destruction were determined. Comparison of the oxidative activities of the different types of exhaust condensates clearly showed that the exhaust condensate derived from the four-stroke car equipped with a three-way catalytic converter exhibited by far the lowest oxidative and destructive power. PMID:1283938

  11. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, January 1, 1995--March 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, E.; Perry, D.L.; Heinemann, H.

    1995-03-01

    The synthesis of ethane and ethylene from methane and oxygen will be carried out in novel hydrogen transport inorganic membranes and in cyclic reactors in order to prevent undesirable secondary reactions of C{sub 2} molecules to CO and CO{sub 2}. Neither inorganic membrane reactors nor cyclic tubular reactors are presently used in commercial processes. Their application to catalytic reactions represents a novel application of engineering and solid-state chemistry concepts to catalytic reactions. Our approach combines high temperature membrane and cyclic experimental reactors, synthesis and characterization of thin membrane films and of high surface area catalysts, and detailed models of complex gas phase and surface reactions involved in oxidative coupling. We anticipate that this approach will lead to novel reactors for carrying our kinetic-controlled sequential reactions, such as the oxidative coupling of methane. Careful spectrographic and wet chemical analyses of fresh and silent catalysts have shown considerable differences which have permitted conclusions as to the source of deactivation. Our activities in the first quarter FYI 995 have focused on the synthesis, structural characterization, and catalytic evaluation of membrane films, disks, and reactors. We have also continued to exploit reaction-transport models to predict the performance of membrane, cyclic, and recycle reactors in the oxidative coupling of methane.

  12. ONO-pincer ruthenium complex-bound norvaline for efficient catalytic oxidation of methoxybenzenes with hydrogen peroxide.

    Science.gov (United States)

    Yoshida, Ryota; Isozaki, Katsuhiro; Yokoi, Tomoya; Yasuda, Nobuhiro; Sadakane, Koichiro; Iwamoto, Takahiro; Takaya, Hikaru; Nakamura, Masaharu

    2016-08-21

    The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-l-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity. PMID:27314504

  13. MERCURY OXIDATION PROMOTED BY A SELECTIVE CATALYTIC REDUCTION CATALYST UNDER SIMULATED POWDER RIVER BASIN COAL COMBUSTION CONDITIONS

    Science.gov (United States)

    A bench-scale reactor consisting of a natural gas burner and an electrically heated reactor housing a selective catalytic reduction (SCR) catalyst was constructed for studying elemental mercury oxidation under SCR conditions. A low sulfur Power River Basin (PRB) coal combustion ...

  14. Catalytic Performance of Zeolite-Supported Vanadia in the Aerobic Oxidation of 5-hydroxymethylfurfural to 2,5- diformylfuran

    DEFF Research Database (Denmark)

    Sádaba, Irantzu; Gorbanev, Yury; Kegnæs, Søren;

    2013-01-01

    The catalytic performance of zeolite-supported vanadia catalysts was examined for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) in organic solvents such as N,N-dimethylformamide (DMF), methyl isobutyl ketone, toluene, trifluorotoluene and DMSO. Catalysts based on...

  15. Construction and biofunctional evaluation of electrospun vascular graft loaded with selenocystamine for in situ catalytic generation of nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Siyuan; An, Jun; Weng, Lei [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Li, Yandong [Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China); Xu, Han; Wang, Yaping; Ding, Dan; Kong, Deling [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Wang, Shufang, E-mail: wangshufang@nankai.edu.cn [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2014-12-01

    Construction and biofunctional evaluation of a novel vascular graft with in situ catalytic generation of nitric oxide were described in this paper. Poly α-lysine and poly (γ-glutamic acid) were deposited alternately onto the surface of an electrospun poly ε-caprolactone matrix via electrostatic layer-by-layer self-assembly, and then selenocystamine was loaded as a catalyst. Measurement of in vitro catalytic generation of nitric oxide demonstrated that this catalyst-loaded material could considerably accelerate the release of nitric oxide from S-nitrosoglutathione. A fibroblast proliferation assay showed that the material possessed satisfactory cellular compatibility. The catalyst-loaded material could inhibit the spread of smooth muscle cells in the presence of nitric oxide donors. In arteriovenous-shunt experiment, the catalyst-loaded graft exhibited good anti-thrombotic property where it could prevent acute thrombosis by decreasing the adhesion and activation of platelets and other blood cells. These data suggest a new method of building vascular grafts with improved hemocompatibility and biological functions. - Highlights: • A porous small-diameter vascular graft was prepared by electrospinning. • Selenocystamine was loaded for in situ catalytic and sustained NO generation. • There was a significant catalytic NO generation on the catalyst-loaded sample. • The spread of smooth muscle cells was inhibited on the catalyst-loaded sample. • The catalyst-loaded sample showed anti-thrombotic property in AV-shunt experiment.

  16. Catalytic upgrading of sugar fractions from pyrolysis oils in supercritical mono-alcohols over Cu doped porous metal oxide

    NARCIS (Netherlands)

    Yin, Wang; Venderbosch, Hendrikus; Bottari, Giovanni; Krawzcyk, Krzysztof K.; Barta, Katalin; Heeres, Hero Jan

    2015-01-01

    In this work, we report on the catalytic valorization of sugar fractions, obtained by aqueous phase extraction of fast pyrolysis oils, in supercritical methanol (scMeOH) and ethanol (scEtOH) over a copper doped porous metal oxide (Cu-PMO). The product mixtures obtained are, in principle, suitable fo

  17. Construction and biofunctional evaluation of electrospun vascular graft loaded with selenocystamine for in situ catalytic generation of nitric oxide

    International Nuclear Information System (INIS)

    Construction and biofunctional evaluation of a novel vascular graft with in situ catalytic generation of nitric oxide were described in this paper. Poly α-lysine and poly (γ-glutamic acid) were deposited alternately onto the surface of an electrospun poly ε-caprolactone matrix via electrostatic layer-by-layer self-assembly, and then selenocystamine was loaded as a catalyst. Measurement of in vitro catalytic generation of nitric oxide demonstrated that this catalyst-loaded material could considerably accelerate the release of nitric oxide from S-nitrosoglutathione. A fibroblast proliferation assay showed that the material possessed satisfactory cellular compatibility. The catalyst-loaded material could inhibit the spread of smooth muscle cells in the presence of nitric oxide donors. In arteriovenous-shunt experiment, the catalyst-loaded graft exhibited good anti-thrombotic property where it could prevent acute thrombosis by decreasing the adhesion and activation of platelets and other blood cells. These data suggest a new method of building vascular grafts with improved hemocompatibility and biological functions. - Highlights: • A porous small-diameter vascular graft was prepared by electrospinning. • Selenocystamine was loaded for in situ catalytic and sustained NO generation. • There was a significant catalytic NO generation on the catalyst-loaded sample. • The spread of smooth muscle cells was inhibited on the catalyst-loaded sample. • The catalyst-loaded sample showed anti-thrombotic property in AV-shunt experiment

  18. Oxidation of Borneol to Camphor Using Oxone and Catalytic Sodium Chloride: A Green Experiment for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Lang, Patrick T.; Harned, Andrew M.; Wissinger, Jane E.

    2011-01-01

    A new green oxidation procedure was developed for the undergraduate organic teaching laboratories using Oxone and a catalytic quantity of sodium chloride for the conversion of borneol to camphor. This simple 1 h, room temperature reaction afforded high quality and yield of product, was environmentally friendly, and produced negligible quantities…

  19. Preparation of macroparticle Pt-ST/DVB and Pt-PTFE and study of catalytic oxidation HT

    International Nuclear Information System (INIS)

    Macroparticle hydrophobic supporter, ST/DVB and PTFE, are prepared by two order polymerization and with a reagent for making hole through dissolving out, respectively. Then two macroparticle hydrophobic catalysts are prepared by immersing the relevant supporter in H2PtCl6 solution. The kinetics of catalytic oxidation of the catalysts to HT is studied at ambient temperature

  20. A green surfactant-assisted synthesis of hierarchical TS-1 zeolites with excellent catalytic properties for oxidative desulfurization.

    Science.gov (United States)

    Du, Shuting; Li, Fen; Sun, Qiming; Wang, Ning; Jia, Mingjun; Yu, Jihong

    2016-02-25

    Hierarchical TS-1 zeolites with uniform intracrystalline mesopores have been successfully synthesized through the hydrothermal method by using the green and cheap surfactant Triton X-100 as the mesoporous template. The resultant materials exhibit remarkably enhanced catalytic activity in oxidative desulfurization reactions compared to the conventional TS-1 zeolite. PMID:26881277