Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The add...Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The addition of Pt to Pd-based catalysts is found to be the most effective and promising method.However,distinct states of existence of Pt can affect the catalytic performance to different degrees,even negatively.Therefore,the impact mechanism of Pt on Pd-based catalysts needs to be further understood.In this work,A-site defective La_(0.9)AlO_(x)perovskite was used as a support,and the state of Pt in catalysts was regulated by adjusting the introducing sequence of Pd and Pt,It is found that only when Pt is introduced preferentially,the activity and water resistance of the bimetal can be improved.Combining a series of characterization results of the fresh catalysts,reduced catalysts,and the samples after reduction and use,it is found that the higher Pt^(2+)content in the catalyst is the main reason for promoting bimetallic properties,while more Pt0has an inhibitory effect.This work provides a new understanding of the promotion effect of Pt on Pd-Pt bimetal in the catalytic oxidation reaction of methane.展开更多
Catalytically-grown carbon nanofibers of two different conformations, fishbone and parallel types of the arrangement of carbon layers, were employed as the support of Pd-Pt metal catalysts for the hydrogenation of nap...Catalytically-grown carbon nanofibers of two different conformations, fishbone and parallel types of the arrangement of carbon layers, were employed as the support of Pd-Pt metal catalysts for the hydrogenation of naphthalene to tetralin. The sulfur tolerance of the catalyst system was investigated with the addition of 0.05% thiophene to the reactant of naphthalene in the process. The dispersion of Pd-Pt metal particles on the support was observed with a HREM and a pulsed hydrogen chemisorption method. The hydrogenation reaction of naphthalene was carried out in a CSTR at 250℃ and with the hydrogen pressure of 6 MPa. The results showed that the Pd-Pt catalyst supported on the carbon nanofibers was active in the process. The Pd-Pt metal catalyst supported on the parallel carbon nanofibers showed a higher sulfur tolerance than that on the fishbone carbon nanofibers. The reason may be attributed to their different conformations of the carbon layers, which leads to the different interaction of carbon layers with the supported metal particles.展开更多
Activity and stability of 1%Pd-0.2%Pt/Al2O3 and 1%Pd-0.2%Pt/0.6%Ce/Al2O3 catalysts prepared by impregnation method for catalytic combustion of methane in air were investigated. The catalysts before and after reaction ...Activity and stability of 1%Pd-0.2%Pt/Al2O3 and 1%Pd-0.2%Pt/0.6%Ce/Al2O3 catalysts prepared by impregnation method for catalytic combustion of methane in air were investigated. The catalysts before and after reaction were characterized by BET, CO chemisorption, XRD and XPS techniques. Results showed that the presence of Ce significantly increased the activity and thermal stability of the Pd-Pt/Al2O3 catalyst towards methane combustion, which could be attributed to more highly-dispersed active PdO particles over the Pd-Pt/Ce/Al2O3 catalyst surface as well as the retarded sintering of PdO and the maintained oxidized state of surface Pd during the combustion process in the presence of Ce.展开更多
基金Project supported by the National Key Research and Development Program(2022YFB3504200)National Natrual Science Foundation of China(22376061,21922602,22076047,U21A20326)+1 种基金Shanghai Science and Technology Innovation Action Plan(20dz1204200)Fundamental Re search Funds for the Central Universities。
文摘Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The addition of Pt to Pd-based catalysts is found to be the most effective and promising method.However,distinct states of existence of Pt can affect the catalytic performance to different degrees,even negatively.Therefore,the impact mechanism of Pt on Pd-based catalysts needs to be further understood.In this work,A-site defective La_(0.9)AlO_(x)perovskite was used as a support,and the state of Pt in catalysts was regulated by adjusting the introducing sequence of Pd and Pt,It is found that only when Pt is introduced preferentially,the activity and water resistance of the bimetal can be improved.Combining a series of characterization results of the fresh catalysts,reduced catalysts,and the samples after reduction and use,it is found that the higher Pt^(2+)content in the catalyst is the main reason for promoting bimetallic properties,while more Pt0has an inhibitory effect.This work provides a new understanding of the promotion effect of Pt on Pd-Pt bimetal in the catalytic oxidation reaction of methane.
文摘Catalytically-grown carbon nanofibers of two different conformations, fishbone and parallel types of the arrangement of carbon layers, were employed as the support of Pd-Pt metal catalysts for the hydrogenation of naphthalene to tetralin. The sulfur tolerance of the catalyst system was investigated with the addition of 0.05% thiophene to the reactant of naphthalene in the process. The dispersion of Pd-Pt metal particles on the support was observed with a HREM and a pulsed hydrogen chemisorption method. The hydrogenation reaction of naphthalene was carried out in a CSTR at 250℃ and with the hydrogen pressure of 6 MPa. The results showed that the Pd-Pt catalyst supported on the carbon nanofibers was active in the process. The Pd-Pt metal catalyst supported on the parallel carbon nanofibers showed a higher sulfur tolerance than that on the fishbone carbon nanofibers. The reason may be attributed to their different conformations of the carbon layers, which leads to the different interaction of carbon layers with the supported metal particles.
基金supported by the National High Technology Research and Development Program (863) of China (No.2010AA064904)
文摘Activity and stability of 1%Pd-0.2%Pt/Al2O3 and 1%Pd-0.2%Pt/0.6%Ce/Al2O3 catalysts prepared by impregnation method for catalytic combustion of methane in air were investigated. The catalysts before and after reaction were characterized by BET, CO chemisorption, XRD and XPS techniques. Results showed that the presence of Ce significantly increased the activity and thermal stability of the Pd-Pt/Al2O3 catalyst towards methane combustion, which could be attributed to more highly-dispersed active PdO particles over the Pd-Pt/Ce/Al2O3 catalyst surface as well as the retarded sintering of PdO and the maintained oxidized state of surface Pd during the combustion process in the presence of Ce.
