A series of ZrO2 catalysts were prepared by treating ZrO（OH）2 hydrogel with different alcohol solvents （C2-C4 alcohols） and calcining under N2 flow at 773 K for 3 h. The obtained ZrO2 catalysts were systematically...A series of ZrO2 catalysts were prepared by treating ZrO（OH）2 hydrogel with different alcohol solvents （C2-C4 alcohols） and calcining under N2 flow at 773 K for 3 h. The obtained ZrO2 catalysts were systematically characterized by the methods of N2 adsorption-desorption, powder X-ray diffraction, NH3 temperature-programmed desorption, and CO2 temperature-programmed desorption. The catalytic performance of each catalyst was evaluated in the selective synthesis of iso-C4 （isobutene and isobutane） and light olefins （C2-C4） from CO hydrogenation. The specific surface area increased for the ZrO2 catalysts obtained by treating ZrO（OH）2 hydrogel with different alcohol solvents. The amounts of both acidic and basic sites on the catalyst surface increased obviously. The catalytic activity （CO conversion） of ZrO2 catalysts also increased after the treatment with different alcohol solvents. The nighest activity was obtained over the catalyst which was pretreated with isopropanol. However, alcohol solvent treatment retarded the transformation of ZrO2 crystal structure from tetragonal phase to monoclinic phase, and subsequently resulted in the decrease of monoclinic phase in ZrO2, which led to the decrease of olefin selectivity in corresponding hydrocarbon products （C2-C4/CH）.展开更多
Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be di...Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be divided into three reaction zones, namely pre-reaction zone, fierce reaction zone, and post-reaction zone, when the temperature was high enough to initiate a reaction. The oxidation of methane proceeded and was completed mostly in the fierce reaction zone. When the reactant mixture entered the post-reaction zone, only a small amount of produced methanol would bring about secondary reactions, because molecular oxygen had been exhausted in the fierce reaction zone. A catalyst, if necessary, should be placed either in the pre-reaction zone, to initiate a partial oxidation reaction at a lower temperature, or in the fierce reaction zone to control the homogeneous free radical reaction.展开更多
The trace amount of CO in H2-rich gas poisons Pt electrode when it is adopted as feedstock for proton-exchange-membrane fuel cells.Preferential oxidation of CO(PROX)is a promising approach to selectively oxidize the t...The trace amount of CO in H2-rich gas poisons Pt electrode when it is adopted as feedstock for proton-exchange-membrane fuel cells.Preferential oxidation of CO(PROX)is a promising approach to selectively oxidize the trace amount of CO while keeping H2 unoxidized.Catalyst plays important roles in PROX.To date,enormous catalysts have been developed for PROX.Summarizing the catalysts developed for PROX and unveiling the reaction mechanism could definitely advance this research field.Herein,in this review,according to the nature of the active sites on the catalysts,we classify the catalysts into group VIII metal-based catalyst,group IB metal-based catalysts,group VIII-group IB bimetallic catalysts,transitional metal oxide catalysts as well as others,describe the progress of the catalysts in PROX in the latest five years,and extract the underlying reaction mechanism,with the aim to provide guidance for the rational design of efficient catalysts in the future.展开更多
基金supported by the the National High Technology Research and Development Program of China (2007AA05Z332)
文摘A series of ZrO2 catalysts were prepared by treating ZrO（OH）2 hydrogel with different alcohol solvents （C2-C4 alcohols） and calcining under N2 flow at 773 K for 3 h. The obtained ZrO2 catalysts were systematically characterized by the methods of N2 adsorption-desorption, powder X-ray diffraction, NH3 temperature-programmed desorption, and CO2 temperature-programmed desorption. The catalytic performance of each catalyst was evaluated in the selective synthesis of iso-C4 （isobutene and isobutane） and light olefins （C2-C4） from CO hydrogenation. The specific surface area increased for the ZrO2 catalysts obtained by treating ZrO（OH）2 hydrogel with different alcohol solvents. The amounts of both acidic and basic sites on the catalyst surface increased obviously. The catalytic activity （CO conversion） of ZrO2 catalysts also increased after the treatment with different alcohol solvents. The nighest activity was obtained over the catalyst which was pretreated with isopropanol. However, alcohol solvent treatment retarded the transformation of ZrO2 crystal structure from tetragonal phase to monoclinic phase, and subsequently resulted in the decrease of monoclinic phase in ZrO2, which led to the decrease of olefin selectivity in corresponding hydrocarbon products （C2-C4/CH）.
文摘Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be divided into three reaction zones, namely pre-reaction zone, fierce reaction zone, and post-reaction zone, when the temperature was high enough to initiate a reaction. The oxidation of methane proceeded and was completed mostly in the fierce reaction zone. When the reactant mixture entered the post-reaction zone, only a small amount of produced methanol would bring about secondary reactions, because molecular oxygen had been exhausted in the fierce reaction zone. A catalyst, if necessary, should be placed either in the pre-reaction zone, to initiate a partial oxidation reaction at a lower temperature, or in the fierce reaction zone to control the homogeneous free radical reaction.
基金support from the National Natural Science Foundation of China(No.21902116)the Scientific Research Foundation of Liaoning province of China(No.JQL202015403).
文摘The trace amount of CO in H2-rich gas poisons Pt electrode when it is adopted as feedstock for proton-exchange-membrane fuel cells.Preferential oxidation of CO(PROX)is a promising approach to selectively oxidize the trace amount of CO while keeping H2 unoxidized.Catalyst plays important roles in PROX.To date,enormous catalysts have been developed for PROX.Summarizing the catalysts developed for PROX and unveiling the reaction mechanism could definitely advance this research field.Herein,in this review,according to the nature of the active sites on the catalysts,we classify the catalysts into group VIII metal-based catalyst,group IB metal-based catalysts,group VIII-group IB bimetallic catalysts,transitional metal oxide catalysts as well as others,describe the progress of the catalysts in PROX in the latest five years,and extract the underlying reaction mechanism,with the aim to provide guidance for the rational design of efficient catalysts in the future.
