Rhodium-based catalysts were prepared by impregnation,treated with glow discharge plasma,character-ized by X-ray diffraction,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,H2 temperature-programm...Rhodium-based catalysts were prepared by impregnation,treated with glow discharge plasma,character-ized by X-ray diffraction,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,H2 temperature-programmed desorption and CO temperature-programmed desorption,and investigated for oxygenate synthesis from CO hydrogenation.Based on the characterization results,plasma treatment endowed the samples with smaller particle size,higher dispersion of active components,and an enrichment of active components on the surface as well.As a result,the reducibility and adsorption properties were modified.In cata-lytic tests,the catalytic activity for CO hydrogenation over the samples treated by plasma was improved remarkably:the conversion of CO and the yield of oxygenates increased at most by a factor of 78.62%and 51.96%,respectively,while the selectivity of ethanol and methanol in the oxygenates was enhanced as well.展开更多
Gas phase hydrogenation of crotonaldehyde was performed over 1 wt% Rh/ZnO-Al2O3 catalysts with various Zn/Rh atomic ratios. Monometallic Rh/Al2O3 was also prepared for comparison. The samples were prepared by the succ...Gas phase hydrogenation of crotonaldehyde was performed over 1 wt% Rh/ZnO-Al2O3 catalysts with various Zn/Rh atomic ratios. Monometallic Rh/Al2O3 was also prepared for comparison. The samples were prepared by the successive impregnation of Al2O3 with chlo-ride precursors of zinc and rhodium. The solids have been characterized by H2 chemisorption,temperature-programmed reduction,scanning electron microscopy,and cyclohexane dehydrogenation. Their catalytic behaviour in the gas phase crotonaldehyde hydrogenation reaction after reduction treatment in flowing hydrogen at 723 K was investigated. The relationship between catalytic activity,selectivity for crotyl alcohol,and physicochemical properties of the catalysts was examined. Results obtained showed that the presence of Zn clearly promotes the hydrogenation of the carbonyl bond. The catalyst with Zn/Rh atomic ratio of 5 displayed good catalytic stability and the highest selectivity for crotyl alcohol(70%) along with alloy formation.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.20590360)the Innovation Foundation of Sichuan University(2005CF07)+1 种基金the Ministry of Science and Technology of China(Grant No.2005CB221406)the New Century Excellent Talent Project of Ministry of Education of China(NCET-05-783).
文摘Rhodium-based catalysts were prepared by impregnation,treated with glow discharge plasma,character-ized by X-ray diffraction,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,H2 temperature-programmed desorption and CO temperature-programmed desorption,and investigated for oxygenate synthesis from CO hydrogenation.Based on the characterization results,plasma treatment endowed the samples with smaller particle size,higher dispersion of active components,and an enrichment of active components on the surface as well.As a result,the reducibility and adsorption properties were modified.In cata-lytic tests,the catalytic activity for CO hydrogenation over the samples treated by plasma was improved remarkably:the conversion of CO and the yield of oxygenates increased at most by a factor of 78.62%and 51.96%,respectively,while the selectivity of ethanol and methanol in the oxygenates was enhanced as well.
基金supported by the Centre de Recherche Scientifique et Technique en Analyses Physico-Chimiques (C.R.A.P.C)Université des Sciences et de la Technologie,Houari Boumediene (USTHB)
文摘Gas phase hydrogenation of crotonaldehyde was performed over 1 wt% Rh/ZnO-Al2O3 catalysts with various Zn/Rh atomic ratios. Monometallic Rh/Al2O3 was also prepared for comparison. The samples were prepared by the successive impregnation of Al2O3 with chlo-ride precursors of zinc and rhodium. The solids have been characterized by H2 chemisorption,temperature-programmed reduction,scanning electron microscopy,and cyclohexane dehydrogenation. Their catalytic behaviour in the gas phase crotonaldehyde hydrogenation reaction after reduction treatment in flowing hydrogen at 723 K was investigated. The relationship between catalytic activity,selectivity for crotyl alcohol,and physicochemical properties of the catalysts was examined. Results obtained showed that the presence of Zn clearly promotes the hydrogenation of the carbonyl bond. The catalyst with Zn/Rh atomic ratio of 5 displayed good catalytic stability and the highest selectivity for crotyl alcohol(70%) along with alloy formation.
