Partial oxidation of methane to syngas （POM） over Rh/SiO2 catalyst was investigated using in-situ FT-IR. When methane interacted with 1.0wt%Rh/SiO2 catalyst, it was dissociated to adsorbed hydrogen and CHx species. ...Partial oxidation of methane to syngas （POM） over Rh/SiO2 catalyst was investigated using in-situ FT-IR. When methane interacted with 1.0wt%Rh/SiO2 catalyst, it was dissociated to adsorbed hydrogen and CHx species. The adsorbed hydrogen atoms were transferred to SiO2 surface by ＂spill-over＂ and reacted with lattice oxygen to form surface -OH species. POM mechanism was investigated over Rh/SiO2 catalyst using in-situ FT-IR. It was found that CO2 was formed before CO could be detected when CH4 and O2 were introduced over the preoxidized Rh/SiO2 catalyst, whereas CO was detected before CO2 was formed over the prereduced Rh/SiO2 catalyst.展开更多
A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous high-surface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of mass transfer in water/oil biphasic ...A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous high-surface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of mass transfer in water/oil biphasic media for the hydroformylation of higher olefins. The catalytic performance for hydroformylation on this biphasic TPPTS-Rh/SiO2 catalyst system was higher than those of the traditional biphasic HRhCO(TPPTS)3 systems, owing to the chemical bonds between the highly dispersed Rh metal particles and the TPPTS ligands. The catalyst system is applicable for hydroformylation of higher olefins such as 1-dodecene.展开更多
Rh/SiO2 was prepared for the oxidative bromination of methane. The catalyst was prepared by calcination at different temperatures and for different times to obtain catalysts with different specific surface areas for t...Rh/SiO2 was prepared for the oxidative bromination of methane. The catalyst was prepared by calcination at different temperatures and for different times to obtain catalysts with different specific surface areas for the purposes of producing either CH3Br or CH3Br and CO. It was found that the catalyst having a low specific surface area （calcined at relatively high temperature） favors the selective oxidation of methane to prepare CH3Br, while the catalyst having a high specific surface area favors the deeper partial oxidation of methane, which is good for CH3Br and CO preparation, The 650 h on stream life-time test revealed that the catalytic performance of the 0.4Rh/SiO2-900-10 catalyst was excellent. Both methane conversion and CH3Br selectivity kept increasing trends during the life-time test. No matter how serious was the Rh leaching during the reaction, the 0.4Rh/SiO2-900-10 catalyst did not deactivate at all.展开更多
A phosphite ligand modified Rh/SiO2 catalyst has been developed for hydroformylation of internal olefins to linear aldehydes, which showed high activity and regioselectivity and could be separated easily by filtration...A phosphite ligand modified Rh/SiO2 catalyst has been developed for hydroformylation of internal olefins to linear aldehydes, which showed high activity and regioselectivity and could be separated easily by filtration after reaction in an autoclave. Effects of reaction temperature and syngas pressure on the performances of the catalyst in the reaction were also investigated.展开更多
EHMO calculations and orbital analysis of fragments were performed for the Synthetic reactions of oxygenates in Fischer-Tropsch synthesis using a butterfly model for four different metals (Nim Ru, Rh, Pd)supported on ...EHMO calculations and orbital analysis of fragments were performed for the Synthetic reactions of oxygenates in Fischer-Tropsch synthesis using a butterfly model for four different metals (Nim Ru, Rh, Pd)supported on SiO2 as catalysts. Four processest CO dissociation, coupling of CO and H to produce CHO.insertion of CO to M-CH3; insertion of CH2 to M-CH3 have been calculated. We compared the degree of CO bond activation and the banters of the foregoing processes for these four catalysts, it can be shown that Ni/SiO2 is a methanation catalyst, Ru/SiO2 and Rh/SiO2 can produce C2-oxygenated compound (acetaldehyde), especially Rh/SiO2 is a good catalyst for producing it, and Pd/SiO2 is a methanol Synthesis catalyst.展开更多
The effects of ethanol vapor pretreatment on the performance of CrOx/SiO2 catalysts during the dehydrogenation of propane to propylene were studied with and without the presence of CO2.The catalyst pretreated with eth...The effects of ethanol vapor pretreatment on the performance of CrOx/SiO2 catalysts during the dehydrogenation of propane to propylene were studied with and without the presence of CO2.The catalyst pretreated with ethanol vapor exhibited better catalytic activity than the pristine CrOx/SiO2,generating 41.4% propane conversion and 84.8% propylene selectivity.The various catalyst samples prepared were characterized by X-ray diffraction,transmission electron microscopy,temperature-programmed reduction,X-ray photoelectron spectroscopy and reflectance UV-Vis spectroscopy.The data show that coordinative Cr^3＋ species represent the active sites during the dehydrogenation of propane and that these species serve as precursors for the generation of Cr^3＋.Cr^3＋ is reduced during the reaction,leading to a decrease in catalytic activity.Following ethanol vapor pretreatment,the reduced CrOx in the catalyst is readily re-oxidized to Cr^6＋ by CO2.The pretreated catalyst thus exhibits high activity during the propane dehydrogenation reaction by maintaining the active Cr^3＋ states.展开更多
Methyl glycolate is a good solvent and can be used as feedstock for the synthesis of some important organic chemicals. Catalytic hydrogenation of dimethyl oxalate （DMO） over copper-silver catalyst supported on silic...Methyl glycolate is a good solvent and can be used as feedstock for the synthesis of some important organic chemicals. Catalytic hydrogenation of dimethyl oxalate （DMO） over copper-silver catalyst supported on silica was studied. The Cu-Ag/SiO2 catalyst supported on silica sol was prepared by homogeneous deposition-precipitation of the mixture of aqueous euprammonia complex and silica sol. The proper active temperature of Cu-Ag/SiO2 catalyst for hydrogenation of DMO was 523-623 K. The most preferable reaction conditions for methyl glycolate （MG） were optimized： temperature at 468-478 K, 40-60 mesh catalyst diameter, H2/DMO ratio 40, and 1.0 h^-1 of LHSV.展开更多
A series of indium oxide‐modified Cu/SiO2catalysts were synthesized and used to produce ethanol via methyl acetate hydrogenation.In‐Cu/SiO2catalyst containing1.0wt%In2O3exhibited the best catalytic activity and stab...A series of indium oxide‐modified Cu/SiO2catalysts were synthesized and used to produce ethanol via methyl acetate hydrogenation.In‐Cu/SiO2catalyst containing1.0wt%In2O3exhibited the best catalytic activity and stability.The physicochemical properties of the synthesized catalysts were investigated using several characterization methods and the results showed that introducing suitable indium to Cu/SiO2increased the copper dispersion,diminished the copper crystallite size,and enriched the surface Cu+concentration.Furthermore,the Cu/SiO2catalyst gradually deactivated during the stability test,which was mainly attributed to copper sintering and the valence change in surface copper species.In contrast,indium addition can inhibit the thermal transmigration and accumulation of copper nanoparticles to stabilize the catalyst.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.展开更多
基金This study was supported by the grant of 2004C31053 from the Ministry of Science and Technology of Zhejiang Province, China, and the grant of Y404305 from the Natural Science Foundation of Zhejiang Province, Chinathe grant of 20673101, 20673102 from National Natural Science Foundation of China.
文摘Partial oxidation of methane to syngas （POM） over Rh/SiO2 catalyst was investigated using in-situ FT-IR. When methane interacted with 1.0wt%Rh/SiO2 catalyst, it was dissociated to adsorbed hydrogen and CHx species. The adsorbed hydrogen atoms were transferred to SiO2 surface by ＂spill-over＂ and reacted with lattice oxygen to form surface -OH species. POM mechanism was investigated over Rh/SiO2 catalyst using in-situ FT-IR. It was found that CO2 was formed before CO could be detected when CH4 and O2 were introduced over the preoxidized Rh/SiO2 catalyst, whereas CO was detected before CO2 was formed over the prereduced Rh/SiO2 catalyst.
文摘A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous high-surface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of mass transfer in water/oil biphasic media for the hydroformylation of higher olefins. The catalytic performance for hydroformylation on this biphasic TPPTS-Rh/SiO2 catalyst system was higher than those of the traditional biphasic HRhCO(TPPTS)3 systems, owing to the chemical bonds between the highly dispersed Rh metal particles and the TPPTS ligands. The catalyst system is applicable for hydroformylation of higher olefins such as 1-dodecene.
基金supported by the Chinese Ministry of Education Project No.107132the Chinese Ministry of Science and Technology Project No.2005CB221406, 2006BAE02B05
文摘Rh/SiO2 was prepared for the oxidative bromination of methane. The catalyst was prepared by calcination at different temperatures and for different times to obtain catalysts with different specific surface areas for the purposes of producing either CH3Br or CH3Br and CO. It was found that the catalyst having a low specific surface area （calcined at relatively high temperature） favors the selective oxidation of methane to prepare CH3Br, while the catalyst having a high specific surface area favors the deeper partial oxidation of methane, which is good for CH3Br and CO preparation, The 650 h on stream life-time test revealed that the catalytic performance of the 0.4Rh/SiO2-900-10 catalyst was excellent. Both methane conversion and CH3Br selectivity kept increasing trends during the life-time test. No matter how serious was the Rh leaching during the reaction, the 0.4Rh/SiO2-900-10 catalyst did not deactivate at all.
基金supported by the National Key Fundamental Research Development Plan("973"Plan,No.2009CB623503)
文摘A phosphite ligand modified Rh/SiO2 catalyst has been developed for hydroformylation of internal olefins to linear aldehydes, which showed high activity and regioselectivity and could be separated easily by filtration after reaction in an autoclave. Effects of reaction temperature and syngas pressure on the performances of the catalyst in the reaction were also investigated.
文摘EHMO calculations and orbital analysis of fragments were performed for the Synthetic reactions of oxygenates in Fischer-Tropsch synthesis using a butterfly model for four different metals (Nim Ru, Rh, Pd)supported on SiO2 as catalysts. Four processest CO dissociation, coupling of CO and H to produce CHO.insertion of CO to M-CH3; insertion of CH2 to M-CH3 have been calculated. We compared the degree of CO bond activation and the banters of the foregoing processes for these four catalysts, it can be shown that Ni/SiO2 is a methanation catalyst, Ru/SiO2 and Rh/SiO2 can produce C2-oxygenated compound (acetaldehyde), especially Rh/SiO2 is a good catalyst for producing it, and Pd/SiO2 is a methanol Synthesis catalyst.
基金the financial support from China Postdoctoral Science Foundation (2014M560224)
文摘The effects of ethanol vapor pretreatment on the performance of CrOx/SiO2 catalysts during the dehydrogenation of propane to propylene were studied with and without the presence of CO2.The catalyst pretreated with ethanol vapor exhibited better catalytic activity than the pristine CrOx/SiO2,generating 41.4% propane conversion and 84.8% propylene selectivity.The various catalyst samples prepared were characterized by X-ray diffraction,transmission electron microscopy,temperature-programmed reduction,X-ray photoelectron spectroscopy and reflectance UV-Vis spectroscopy.The data show that coordinative Cr^3＋ species represent the active sites during the dehydrogenation of propane and that these species serve as precursors for the generation of Cr^3＋.Cr^3＋ is reduced during the reaction,leading to a decrease in catalytic activity.Following ethanol vapor pretreatment,the reduced CrOx in the catalyst is readily re-oxidized to Cr^6＋ by CO2.The pretreated catalyst thus exhibits high activity during the propane dehydrogenation reaction by maintaining the active Cr^3＋ states.
文摘Methyl glycolate is a good solvent and can be used as feedstock for the synthesis of some important organic chemicals. Catalytic hydrogenation of dimethyl oxalate （DMO） over copper-silver catalyst supported on silica was studied. The Cu-Ag/SiO2 catalyst supported on silica sol was prepared by homogeneous deposition-precipitation of the mixture of aqueous euprammonia complex and silica sol. The proper active temperature of Cu-Ag/SiO2 catalyst for hydrogenation of DMO was 523-623 K. The most preferable reaction conditions for methyl glycolate （MG） were optimized： temperature at 468-478 K, 40-60 mesh catalyst diameter, H2/DMO ratio 40, and 1.0 h^-1 of LHSV.
文摘A series of indium oxide‐modified Cu/SiO2catalysts were synthesized and used to produce ethanol via methyl acetate hydrogenation.In‐Cu/SiO2catalyst containing1.0wt%In2O3exhibited the best catalytic activity and stability.The physicochemical properties of the synthesized catalysts were investigated using several characterization methods and the results showed that introducing suitable indium to Cu/SiO2increased the copper dispersion,diminished the copper crystallite size,and enriched the surface Cu+concentration.Furthermore,the Cu/SiO2catalyst gradually deactivated during the stability test,which was mainly attributed to copper sintering and the valence change in surface copper species.In contrast,indium addition can inhibit the thermal transmigration and accumulation of copper nanoparticles to stabilize the catalyst.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.
