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Stéphane Siffert - One of the best experts on this subject based on the ideXlab platform.
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Mixed Oxides Issued from Hydrotalcite Precursors for Toluene and CO Total Oxidation: Comparison of Preparation Method.
Journal of nanoscience and nanotechnology, 2020Co-Authors: Eric Genty, Stéphane Siffert, Christophe Poupin, Cynthia Abou Serhal, Rebecca El Khawaja, Hadi Dib, M. Labaki, Isabelle Mallard, Renaud CousinAbstract:Catalytic Total Oxidation is an effective technique for the treatment of industrial VOCs. This emission is generally accompanied by the presence of other products like CO, NOx or other VOC. In this paper, the development of catalysts for the Total Oxidation of CO and toluene mixture is performed. For this study, Mg6Al₂HT hydrotalcites precursors were synthesized by three different methods: co-precipitation, microwaves and ultrasound assisted method. Hydrotalcite precursors have been used in order to develop mixed oxides after calcination for the catalytic Oxidation test. Hydrotalcite structure as well as the mixed oxides obtained after calcination was studied, by several techniques: XRD, TEM, DTA/TG, BET, N₂ sorption, H₂-TPR. The physico chemical studies revealed modification in the structural characteristics (surface area, porosity) as well as in reducibility properties of the formed mixed oxides. The nanocatalyst issued from microwaves synthesis was the most active in these studied reactions for the Total Oxidation of the mixture. Moreover, addition of CO on the reaction mixture allows obtaining a beneficial effect on the toluene Oxidation.
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Influence of CO addition on the toluene Total Oxidation over Co based mixed oxide catalysts
Applied Catalysis B: Environmental, 2019Co-Authors: Eric Genty, Stéphane Siffert, Julien Brunet, Christophe Poupin, Satu Ojala, Renaud CousinAbstract:Abstract Hydrotalcite like compounds containing Co, Al and Ce were synthesized by co-precipitation. The mixed oxides obtained after calcination were characterized by several techniques: XRD, BET, H2-TPR and XPS. Activities of mixed oxides were evaluated in toluene Total Oxidation in presence or in absence of carbon monoxide. The benzene, benzyl alcohol and benzaldehyde are principal by-products observed during toluene Oxidation in presence of CoAl(Ce) mixed oxides. Moreover, presence of carbon monoxide improves toluene Total Oxidation over CoAlCe mixed oxides. Stability of the two best catalytic materials has been tested in the two conditions and show no deactivation.
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Effect of Ce Addition on MgAl Mixed Oxides for the Total Oxidation of CO and Toluene
Topics in Catalysis, 2018Co-Authors: Eric Genty, Stéphane Siffert, Julien Brunet, Christophe Poupin, Hadi Dib, Renaud CousinAbstract:VOC and CO constitute the principal emission during cold-start of vehicles. In order to decrease this emission at low temperature, this study focuses on the development of new catalysts: MgAlCe mixed oxides issued from the calcination of hydrotalcite precursors. Addition of cerium on the MgAl solid increase the reducibility of catalysts inducing a better catalytic reactivity for the CO and toluene Total Oxidation. Moreover, toluene Oxidation is facilitated at low temperature due to a beneficial effect of CO in the reaction mixture.
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The CoAlCeO Mixed Oxide: An Alternative to Palladium-Based Catalysts for Total Oxidation of Industrial VOCs
Catalysts, 2018Co-Authors: Julien Brunet, Eric Genty, Stéphane Siffert, Cédric Barroo, Fabrice Cazier, Christophe Poupin, Diane Thomas, Guy De Weireld, Thierry Visart De Bocarmé, Renaud CousinAbstract:Catalytic Total Oxidation is an effective technique for the treatment of industrial VOCs principally resulting from industrial processes using solvents, and usually containing mono-aromatics (BTEX) and oxygenated compounds (acetone, ethanol, butanone). The catalytic Total Oxidation of VOCs on noble metal materials is effective. However, the cost of catalysts is a main obstacle for the industrial application of these VOC removal processes. Therefore, the aim of this work is to propose an alternative material to palladium-based catalysts (which are suitable for VOCs’ Total Oxidation): a mixed oxide synthesized in the hydrotalcite way, namely CoAlCeO. This material was compared to four catalytic materials containing palladium, selected according to the literature: Pd/α-Al2O3, Pd/HY, Pd/CeO2 and Pd/γAl2O3. These materials have been studied for the Total Oxidation of toluene, butanone, and VOCs mixtures. Catalysts’ performances were compared, taking into account the Oxidation byproducts emitted from the process. This work highlight that the CoAlCeO catalyst presents better efficiency than Pd-based materials for the Total Oxidation of a VOCs mixture.
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Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation
Catalysts, 2015Co-Authors: Eric Genty, Sylvie Capelle, Stéphane Siffert, Julien Brunet, Christophe Poupin, Sandra Casale, Pascale Massiani, Renaud CousinAbstract:Co6Al2HT hydrotalcite-like compounds were synthesized by three different methods: co-precipitation, microwaves-assisted and ultrasound-assisted methods. The mixed oxides obtained after calcination were studied by several techniques: XRD, TEM, H2-TPR and XPS. They were also tested as catalysts in the reaction of Total Oxidation of toluene. The physico-chemical studies revealed a modification of the structural characteristics (surface area, morphology) as well as of the reducibility of the formed mixed oxides. The solid prepared by microwaves-assisted synthesis was the most active. Furthermore, a relationship between the ratio of Co2+ on the surface, the reducibility of the Co-Al mixed oxide and the T50 in toluene Oxidation was demonstrated. This suggests a Mars Van Krevelen mechanism for toluene Total Oxidation on these catalysts.
Stuart Hamilton Taylor - One of the best experts on this subject based on the ideXlab platform.
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Supported iridium catalysts for the Total Oxidation of short chain alkanes and their mixtures: Influence of the support
Chemical Engineering Journal, 2020Co-Authors: Lukas Schick, Tomas Garcia, Stuart Hamilton Taylor, David J. Morgan, Vicenta González-alfaro, Adrián García, José Manuel López, Said Agouram, Benjamin SolsonaAbstract:Abstract Catalytic Total Oxidation of noxious volatile organic compounds (VOCs) is an important process to remove these compounds from the atmosphere. This is the first systematic study of the influence of the support on the activity of iridium oxide supported catalysts for the Total Oxidation of VOCs. Iridium catalysts supported on titania, γ-alumina, silica and zeolites have been prepared using different calcination temperatures. The activity for the Total Oxidation of short chain alkanes and their mixtures has been evaluated and the physicochemical properties characterized by N2 adsorption, XRD, (HR)TEM, EDX, CO-Chemisorption, TPR, XPS and Raman spectroscopy. Both the calcination temperature and the nature of the support of iridium catalysts play an important role for the catalytic performance. Silica, ZSM-5 zeolites and titania are suitable supports for IrOx, in contrast with γ-alumina. A strong influence of the Lewis acidity of the support on the turnover frequency of the iridium oxide is found. Additionally, for a given support, the calcination temperature has an effect on the catalytic activity. A possible size effect is discussed. However, the major controlling factor is the nature of the support. Therefore, our results provide a guideline towards a rational design of more active IrOx catalysts for the Total Oxidation of VOCs.
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Ceria-zirconia mixed metal oxides prepared via mechanochemical grinding of carbonates for the Total Oxidation of propane and naphthalene
Catalysts, 2019Co-Authors: Parag Shah, Thomas E. Davies, David J. Morgan, Joseph W. H. Burnett, Stuart Hamilton TaylorAbstract:A series of ceria–zirconia mixed metal oxides with varying metal ratios were prepared by the calcination of precursors synthesized by mechanochemical grinding of the metal carbonates, and tested for catalytic naphthalene and propane Total combustion. The mechanically-mixed metal oxides were more active for both propane and naphthalene Total Oxidation compared to the parent metal oxides. Ce0.95Zr0.05Ox was the most active catalyst for the Total combustion of propane and naphthalene. Catalysts were characterized by x-ray diffraction, BET surface area, laser Raman spectroscopy, temperature programmed reduction, scanning electron microscopy with energy dispersive x-ray analysis and x-ray photoelectron spectroscopy techniques. Formation of ceria–zirconia solid solutions was observed for catalysts with a zirconia content of 10% or lower, whereas ceria and zirconia phase separation was observed when zirconia content was above 25%. Surface area increased when ceria and zirconia were mixed, and the reduction temperature of the bulk shifted to lower temperatures upon increasing zirconia content. Incorporation of zirconia was found to increase the relative concentration of surface oxygen defects compared to pure ceria, with low amounts of zirconia showing the greatest increase. The concentration of oxygen defects correlates with propane and naphthalene Total Oxidation activity. The enhanced Total Oxidation activity occurs as a result of the increased number of oxygen defects and the higher surface area. The results demonstrate that mechanochemical preparation from carbonate precursors was an effective route to make active catalysts
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Mechanochemical preparation of ceria-zirconia catalysts for the Total Oxidation of propane and naphthalene Volatile Organic Compounds
Applied Catalysis B: Environmental, 2019Co-Authors: Parag Shah, Thomas E. Davies, Andrew N. Day, David J. Morgan, Stuart Hamilton TaylorAbstract:Abstract A range of ceria-zirconia mixed metal oxide catalysts were synthesised by mechanochemical milling from nitrate precursors and tested for propane and naphthalene Total Oxidation. The mixed CeZrOx metal oxide catalysts were more active compared to pure CeO2 and ZrO2, with the Ce0.90Zr0.10Ox catalyst the most active for both propane and naphthalene Total Oxidation. Catalysts were characterised by XRD, TGA, Raman spectroscopy, BET surface area, XPS, TEM and SEM-EDX techniques. Formation of CeZrOx solid solutions were observed for Zr content ranging from 5 to 25%, and phase separated materials were observed for higher Zr content of 50%. The incorporation of Zr into the CeO2 lattice increased the surface area compared to pure CeO2 and ZrO2, with evidence of a surface enrichment of Zr when concentrations were compared to the bulk. Incorporation of Zr was found to increase the surface concentration of oxygen defects in the CeZrOx mixed metal oxides, the concentration of these defect on the catalysts follows a similar trend to the propane and naphthalene Total Oxidation activity: The increased presence of oxygen defects and reducibility are factors responsible for the enhanced Total Oxidation activity of the mixed metal oxide catalysts and the mechanochemical method is an effective preparation route for these active catalysts.
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Total Oxidation of naphthalene using bulk manganese oxide catalysts
Applied Catalysis A: General, 2013Co-Authors: Tomas Garcia, Stuart Hamilton Taylor, Said Agouram, David Richard Sellick, Francisco Varela, Isabel Vázquez, Ana Dejoz, Benjamin SolsonaAbstract:Several Mn2O3 catalysts have been synthesized using different preparation methods and tested for the Total Oxidation of naphthalene, a model polycyclic aromatic compound. The catalysts have been characterized by several physico-chemical techniques such as XRD, TPR, XPS, EDX and TEM. The surface area of the catalyst seems to be of paramount importance, since the mass normalized activity of catalysts increases as the surface area of the Mn2O3 catalysts increases. Consequently, a high surface area ordered mesoporous Mn2O3 catalyst, obtained through a nanocasting route using mesoporous KIT-6 silica as a hard template, was the most efficient catalyst for the deep Oxidation of naphthalene. In addition, this catalyst also exerts the highest surface area normalized catalytic activity, which can be related to the highest reducibility and mobility of its lattice oxygen. It was also observed that the Mn2O3 crystalline phase presents a higher intrinsic activity than MnO2.
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High activity mesoporous copper doped cerium oxide catalysts for the Total Oxidation of polyaromatic hydrocarbon pollutants
Chemical communications (Cambridge England), 2012Co-Authors: Asunción Aranda, Tomas Garcia, Benjamin Solsona, Said Agouram, E. Aylón, Ramón Murillo, Ana M. Mastral, David Richard Sellick, Stuart Hamilton TaylorAbstract:The doping of mesoporous ceria with copper significantly enhances activity for naphthalene Total Oxidation, the enhanced performance is controlled by the increased concentration of surface oxygen defects.
Renaud Cousin - One of the best experts on this subject based on the ideXlab platform.
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Mixed Oxides Issued from Hydrotalcite Precursors for Toluene and CO Total Oxidation: Comparison of Preparation Method.
Journal of nanoscience and nanotechnology, 2020Co-Authors: Eric Genty, Stéphane Siffert, Christophe Poupin, Cynthia Abou Serhal, Rebecca El Khawaja, Hadi Dib, M. Labaki, Isabelle Mallard, Renaud CousinAbstract:Catalytic Total Oxidation is an effective technique for the treatment of industrial VOCs. This emission is generally accompanied by the presence of other products like CO, NOx or other VOC. In this paper, the development of catalysts for the Total Oxidation of CO and toluene mixture is performed. For this study, Mg6Al₂HT hydrotalcites precursors were synthesized by three different methods: co-precipitation, microwaves and ultrasound assisted method. Hydrotalcite precursors have been used in order to develop mixed oxides after calcination for the catalytic Oxidation test. Hydrotalcite structure as well as the mixed oxides obtained after calcination was studied, by several techniques: XRD, TEM, DTA/TG, BET, N₂ sorption, H₂-TPR. The physico chemical studies revealed modification in the structural characteristics (surface area, porosity) as well as in reducibility properties of the formed mixed oxides. The nanocatalyst issued from microwaves synthesis was the most active in these studied reactions for the Total Oxidation of the mixture. Moreover, addition of CO on the reaction mixture allows obtaining a beneficial effect on the toluene Oxidation.
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Influence of CO addition on the toluene Total Oxidation over Co based mixed oxide catalysts
Applied Catalysis B: Environmental, 2019Co-Authors: Eric Genty, Stéphane Siffert, Julien Brunet, Christophe Poupin, Satu Ojala, Renaud CousinAbstract:Abstract Hydrotalcite like compounds containing Co, Al and Ce were synthesized by co-precipitation. The mixed oxides obtained after calcination were characterized by several techniques: XRD, BET, H2-TPR and XPS. Activities of mixed oxides were evaluated in toluene Total Oxidation in presence or in absence of carbon monoxide. The benzene, benzyl alcohol and benzaldehyde are principal by-products observed during toluene Oxidation in presence of CoAl(Ce) mixed oxides. Moreover, presence of carbon monoxide improves toluene Total Oxidation over CoAlCe mixed oxides. Stability of the two best catalytic materials has been tested in the two conditions and show no deactivation.
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Effect of Ce Addition on MgAl Mixed Oxides for the Total Oxidation of CO and Toluene
Topics in Catalysis, 2018Co-Authors: Eric Genty, Stéphane Siffert, Julien Brunet, Christophe Poupin, Hadi Dib, Renaud CousinAbstract:VOC and CO constitute the principal emission during cold-start of vehicles. In order to decrease this emission at low temperature, this study focuses on the development of new catalysts: MgAlCe mixed oxides issued from the calcination of hydrotalcite precursors. Addition of cerium on the MgAl solid increase the reducibility of catalysts inducing a better catalytic reactivity for the CO and toluene Total Oxidation. Moreover, toluene Oxidation is facilitated at low temperature due to a beneficial effect of CO in the reaction mixture.
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The CoAlCeO Mixed Oxide: An Alternative to Palladium-Based Catalysts for Total Oxidation of Industrial VOCs
Catalysts, 2018Co-Authors: Julien Brunet, Eric Genty, Stéphane Siffert, Cédric Barroo, Fabrice Cazier, Christophe Poupin, Diane Thomas, Guy De Weireld, Thierry Visart De Bocarmé, Renaud CousinAbstract:Catalytic Total Oxidation is an effective technique for the treatment of industrial VOCs principally resulting from industrial processes using solvents, and usually containing mono-aromatics (BTEX) and oxygenated compounds (acetone, ethanol, butanone). The catalytic Total Oxidation of VOCs on noble metal materials is effective. However, the cost of catalysts is a main obstacle for the industrial application of these VOC removal processes. Therefore, the aim of this work is to propose an alternative material to palladium-based catalysts (which are suitable for VOCs’ Total Oxidation): a mixed oxide synthesized in the hydrotalcite way, namely CoAlCeO. This material was compared to four catalytic materials containing palladium, selected according to the literature: Pd/α-Al2O3, Pd/HY, Pd/CeO2 and Pd/γAl2O3. These materials have been studied for the Total Oxidation of toluene, butanone, and VOCs mixtures. Catalysts’ performances were compared, taking into account the Oxidation byproducts emitted from the process. This work highlight that the CoAlCeO catalyst presents better efficiency than Pd-based materials for the Total Oxidation of a VOCs mixture.
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Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation
Catalysts, 2015Co-Authors: Eric Genty, Sylvie Capelle, Stéphane Siffert, Julien Brunet, Christophe Poupin, Sandra Casale, Pascale Massiani, Renaud CousinAbstract:Co6Al2HT hydrotalcite-like compounds were synthesized by three different methods: co-precipitation, microwaves-assisted and ultrasound-assisted methods. The mixed oxides obtained after calcination were studied by several techniques: XRD, TEM, H2-TPR and XPS. They were also tested as catalysts in the reaction of Total Oxidation of toluene. The physico-chemical studies revealed a modification of the structural characteristics (surface area, morphology) as well as of the reducibility of the formed mixed oxides. The solid prepared by microwaves-assisted synthesis was the most active. Furthermore, a relationship between the ratio of Co2+ on the surface, the reducibility of the Co-Al mixed oxide and the T50 in toluene Oxidation was demonstrated. This suggests a Mars Van Krevelen mechanism for toluene Total Oxidation on these catalysts.
G. Wendt - One of the best experts on this subject based on the ideXlab platform.
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LaMnO3 Perovskite Supported Noble Metal Catalysts for the Total Oxidation of Methane
Chemical Engineering & Technology, 2007Co-Authors: Lars Giebeler, D Kießling, G. WendtAbstract:Two series of LaMnO 3 supported noble metal (Pt, Pd, Rh) catalysts prepared by the citrate method and calcined in air at 600 and 800 °C, respectively, were investigated. The catalysts resulting from method A were prepared by simultaneous incorporation of the noble metals during perovskite preparation and those following method B were generated by impregnation of the calcined perovskites with the noble metal compounds. The noble metals form solid solutions with the perovskite lattice. Reduction of the catalysts with hydrogen prior to the catalytic reaction led to a significant enhancement of the catalytic activity. During the catalytic reaction, the noble metal clusters are partially transformed to highly dispersed noble metal oxides or nonstoichiometric noble metal oxide phases, which are the catalytically active phases for the Total Oxidation of methane. The best results were obtained with the Pd containing catalysts prepared by method B.
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mnox zro2 catalysts for the Total Oxidation of methane and chloromethane
Applied Catalysis B-environmental, 2004Co-Authors: D. Döbber, W Schmitz, D Kiesling, G. WendtAbstract:Abstract Zirconia-supported manganese oxide catalysts prepared by wet impregnation and precipitation and calcined at 600 and 800 °C, respectively, in air were characterized by powder X-ray diffraction (XRD), textural investigations, temperature programmed reduction (TPR), temperature programmed oxygen desorption (TPD-O 2 ) and X-ray photoelectron spectroscopy (XPS) measurements. The catalytic activity was tested for the Total Oxidation of methane and chloromethane. The characterization studies showed clearly that both preparation methods result in samples with different supported MnO x phases. Compared with the wet impregnation method higher amounts of nonstoichiometrically disperse MnO x species were formed using precipitation method. The catalytic activity of the MnO x /ZrO 2 catalysts for the Total Oxidation of methane is influenced by the dispersity of the catalytically active MnO x phase. In contrast to the methane Oxidation the support zirconia itself indicates a high catalytic activity for the chloromethane conversion. Moreover, the Total Oxidation of chloromethane is connected with a catalyst deactivation and the formation of small amounts of higher chlorinated methanes as by-products at low reaction temperatures and chlorine. Nonstoichiometric surface basic chlorides (MnO y Cl z , ZrO y Cl z ) are considered as the catalytically active phases for the Total Oxidation of chloromethane.
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MnOx/ZrO2 catalysts for the Total Oxidation of methane and chloromethane
Applied Catalysis B: Environmental, 2004Co-Authors: D. Döbber, D Kießling, W Schmitz, G. WendtAbstract:Abstract Zirconia-supported manganese oxide catalysts prepared by wet impregnation and precipitation and calcined at 600 and 800 °C, respectively, in air were characterized by powder X-ray diffraction (XRD), textural investigations, temperature programmed reduction (TPR), temperature programmed oxygen desorption (TPD-O 2 ) and X-ray photoelectron spectroscopy (XPS) measurements. The catalytic activity was tested for the Total Oxidation of methane and chloromethane. The characterization studies showed clearly that both preparation methods result in samples with different supported MnO x phases. Compared with the wet impregnation method higher amounts of nonstoichiometrically disperse MnO x species were formed using precipitation method. The catalytic activity of the MnO x /ZrO 2 catalysts for the Total Oxidation of methane is influenced by the dispersity of the catalytically active MnO x phase. In contrast to the methane Oxidation the support zirconia itself indicates a high catalytic activity for the chloromethane conversion. Moreover, the Total Oxidation of chloromethane is connected with a catalyst deactivation and the formation of small amounts of higher chlorinated methanes as by-products at low reaction temperatures and chlorine. Nonstoichiometric surface basic chlorides (MnO y Cl z , ZrO y Cl z ) are considered as the catalytically active phases for the Total Oxidation of chloromethane.
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Total Oxidation of Methane and Chlorinated Hydrocarbons on Zirconia Supported A1–xSrxMnO3 Catalysts
Chemical Engineering & Technology, 2004Co-Authors: K. Stephan, D Kießling, M. Hackenberger, G. WendtAbstract:The catalytic behavior of ZrO 2 and ZrO 2 containing 8 mol-% Y 2 O 3 supported A 1-x Sr x MnO 3 (A= La, didymium) perovskites was studied in the Total Oxidation of methane, chloromethane and dichloromethane considering catalyst deactivation and byproduct formation. The perovskites are dispersed on the support surface; clusters with a perovskite-like structure were formed. The supported catalysts are characterized by higher specific surface areas compared with the unsupported ones. Partial substitution of A-site cations by Sr leads to an enhancement of the catalytic activity in the Total Oxidation of methane, but not in the Total Oxidation of chlorinated hydrocarbons (CHC). The catalytic activity of supported and unsupported catalysts is comparable in the Total Oxidation of methane in spite of the significantly lower perovskite content of the supported catalysts. In the CHC conversion the catalytic activity of the supported catalysts is higher than that of the unsupported ones.
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Total Oxidation of Chlorinated Hydrocarbons on A1–xSrxMnO3 Perovskite‐Type Oxide Catalysts – Part II: Catalytic Activity
Chemical Engineering & Technology, 2002Co-Authors: K. Stephan, D Kießling, M. Hackenberger, G. WendtAbstract:The influence of the kind of A-site cation in A 1-x Sr x MnO 3 perovskites (A=La, Pr, Nd, Di (didymium)) on the catalytic activity in the Total Oxidation of methane, chloromethane, dichloromethane, and trichloroethylene has been studied. In contrast to methane, the Total Oxidation of chlorinated hydrocarbons (CHC) is connected with a reversible catalyst deactivation and the formation of byproducts at low reaction temperatures. For the catalysts calcined at 600 and 800°C, resp., the catalytic activity is determined mainly by specific surface area, amount of oxide admixtures and crystallinity of the perovskite. DiMnO 3 showed the highest and PrMnO 3 catalysts the lowest catalytic activity in the Total Oxidation of methane and CHC. Partial substitution of A by Sr leads to an enhancement of the catalytic activity in the Total Oxidation of methane, but not in the Total Oxidation of CHC.
Eric M. Gaigneaux - One of the best experts on this subject based on the ideXlab platform.
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Total Oxidation of propane with a nano ruo2 tio2 catalyst
Applied Catalysis A-general, 2014Co-Authors: Damien P. Debecker, Benjamin Farin, Eric M. Gaigneaux, Clément Sanchez, Capucine SassoyeAbstract:An aqueous colloidal method was used to prepare 2 nm ruthenia nanoparticles from RuCl3 and H2O2. The nanoparticles were subsequently deposited onto a commercial TiO2 support and the obtained nano-RuO2/TiO2 catalyst was tested in the Total Oxidation of propane. This catalyst is very active (T50 of 255 °C) and fully selective to CO2. However, much lower performance is achieved if the catalyst is heated above 300 °C—either ex situ during calcination or in situ in reaction conditions. We show that the changes in activity are strongly correlated with structural and chemical alteration of the catalyst during heating. These modifications are inspected by characterizing the catalyst after various heat treatments (N2-physisorption, XPS, XRD, TEM, H2-TPR). At relatively early stages of heating or reaction (∼150–250 °C) RuO2 nanoparticles migrate, leaving anatase TiO2 particles and accumulating on rutile TiO2 surface. At higher temperature, crystallization and sintering provoke irreversible alteration of the catalyst. We suggest that more active VOC Total Oxidation catalysts could be obtained by avoiding unnecessary calcination step.
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Total Oxidation of propane with a nano-RuO2/TiO2 catalyst
Applied Catalysis A : General, 2014Co-Authors: Damien P. Debecker, Benjamin Farin, Eric M. Gaigneaux, Clément Sanchez, Capucine SassoyeAbstract:An aqueous colloidal method was used to prepare 2 nm ruthenia nanoparticles from RuCl3 and H2O2. The nanoparticles were subsequently deposited onto a commercial TiO2 support and the obtained nanoRuO(2)/TiO2 catalyst was tested in the Total Oxidation of propane. This catalyst is very active (T50 of 255 degrees C) and fully selective to CO2. However, much lower performance is achieved if the catalyst is heated above 300 degrees C-either ex situ during calcination or in situ in reaction conditions. We show that the changes in activity are strongly correlated with structural and chemical alteration of the catalyst during heating. These modifications are inspected by characterizing the catalyst after various heat treatments (N2physisorption, XPS, XRD, TEM, H2-TPR). At relatively early stages of heating or reaction (-''150-250 C) RuO2 nanoparticles migrate, leaving anatase TiO2 particles and accumulating on rutile TiO2 surface. At higher temperature, crystallization and sintering provoke irreversible alteration of the catalyst. We suggest that more active VOC Total Oxidation catalysts could be obtained by avoiding unnecessary calcination step.
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Total Oxidation of propane with a nano-RuO2/TiO2 catalyst
Applied Catalysis A: General, 2014Co-Authors: Damien P. Debecker, Benjamin Farin, Eric M. Gaigneaux, Clément Sanchez, Capucine SassoyeAbstract:An aqueous colloidal method was used to prepare 2 nm ruthenia nanoparticles from RuCl3 and H2O2. The nanoparticles were subsequently deposited onto a commercial TiO2 support and the obtained nano-RuO2/TiO2 catalyst was tested in the Total Oxidation of propane. This catalyst is very active (T50 of 255 °C) and fully selective to CO2. However, much lower performance is achieved if the catalyst is heated above 300 °C—either ex situ during calcination or in situ in reaction conditions. We show that the changes in activity are strongly correlated with structural and chemical alteration of the catalyst during heating. These modifications are inspected by characterizing the catalyst after various heat treatments (N2-physisorption, XPS, XRD, TEM, H2-TPR). At relatively early stages of heating or reaction (∼150–250 °C) RuO2 nanoparticles migrate, leaving anatase TiO2 particles and accumulating on rutile TiO2 surface. At higher temperature, crystallization and sintering provoke irreversible alteration of the catalyst. We suggest that more active VOC Total Oxidation catalysts could be obtained by avoiding unnecessary calcination step.
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Necessary conditions for a synergy between Ag and V2O5 in the Total Oxidation of chlorobenzene
Catalysis Today, 2011Co-Authors: Romain Delaigle, Pierre Eloy, Eric M. GaigneauxAbstract:V2O5/TiO2 catalysts are widely developed for the Total Oxidation of dioxins. However, this study presents an innovative way to improve the performances of V2O5/TiO2 catalysts by the addition of silver. Three kinds of catalysts were synthesized: Ag/TiO2, V2O5/TiO2 and Ag–V2O5/TiO2. The vanadia loading always corresponds to a 0.75 theoretical monolayer while 9 different loadings of silver were explored (0.02–12.5%). This new kind of catalysts is tested in the Total Oxidation of chlorobenzene which is a classical model molecule for dioxins. The samples were characterized by BET, XPS, XRD, ICP-AES and TEM before and after catalytic tests. The specific surface decreases with the increase of the silver loading for Ag/TiO2 and Ag–V2O5/TiO2 catalysts. XPS results show that the addition of silver to a V2O5/TiO2 formulation induces a higher Oxidation state of the vanadium which should be beneficial on the performances. A synergy is indeed observed for several loadings of silver with a maximum at a loading of 0.05 wt.%. This synergistic effect between silver and vanadia can only be achieved in the Total Oxidation of chlorobenzene by choosing appropriate operating conditions, namely conditions avoiding AgCl formation. This synergy is directly linked to an optimal silver loading which offers the best compromise between a high Oxidation state of vanadia without a significant decrease of the specific surface of the catalyst.
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Design of nano-sized FeOx and Au/FeOx catalysts for Total Oxidation of VOC and preferential Oxidation of CO
Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium Louvain-la-Neuve Belgium July 11-15 , 2010Co-Authors: Stefania Albonetti, Eric M. Gaigneaux, Romain Delaigle, Rosa Bonelli, F. TrifiròAbstract:The Total Oxidation of methanol and toluene, chosen as representative VOCs, was investigated over CeO2-supported Au/FeOx catalysts prepared utilizing the bimetallic carbonyl cluster salt [NEt4][AuFe4(CO)16]. Characterization data showed that the catalysts prepared by the reported method exhibit highly and homogeneously dispersed iron oxide species on the ceria support together with small gold nanoparticles, whose size increases on increasing the amount of gold/iron. Addition of iron oxide species did not substantially increase the methanol combustion activity of ceria, whereas the presence of the mixed gold and FeOx species has been found to strongly enhance the activity towards the Total Oxidation of methanol. In the case of the toluene combustion the addition of FeOx or FeOx/Au species caused a significant decrease in the activity of the bare CeO2. The above catalytic behavior was rationalized on the basis of different interactions occurring among gold, iron oxide and cerium oxide, which synergically affects both the reactivity of the surface oxygen and the capacity of the support to adsorb the organic reactant.
