Immobilizing highly dispersed Au nanoparticles onto titanium silicalite-1(TS-1)by a simple impregnation method under light is still a challenging task.In this work;a high photostable Au precursor protected by thiol li...Immobilizing highly dispersed Au nanoparticles onto titanium silicalite-1(TS-1)by a simple impregnation method under light is still a challenging task.In this work;a high photostable Au precursor protected by thiol ligands was firstly synthesized;and the as-prepared Au precursor displayed excellent stability under light for over 30 days;while the Au precursor without thiol ligands formed precipitates after just 2 h under light.Subsequently;the Au precursor protected by thiol ligands was immobilized on the external surface of uncalcined TS-1(i.e.;TS-1-B)by the incipient wetness impregnation method(IWI method)to prepare Au/TS-1-B catalyst.The activity of as-prepared Au/TS-1-B catalyst in the hydro-oxidation of propane to acetone was 1.4 times higher than that of the catalyst prepared by the deposition-precipitation urea method(DPU method).The structures of the Au/TS-1-B catalysts prepared by different methods were analyzed by multiple characterizations.Compared to the Au/TS-1-B catalyst prepared by the DPU method;the Au/TS-1-B catalyst synthesized by the IWI method exhibited a narrower size distribution of Au nanoparticles and had more small Au particles(<2 nm);which is the main reason for its superior activity.Additionally;the effects of gold loadings;reaction temperature and Si/Ti molar ratio on the catalytic performance of the Au/TS-1-B catalyst prepared by the IWI method were also investigated.In addition;the Au/TS-1-B catalyst prepared by the IWI method also exhibited excellent stability for over 140 h.展开更多
Propylene epoxidation by H_(2)and O_(2)to propylene oxide(PO)over the Au-Ti bifunctional catalysts,as an ideal reaction for PO production,has attracted great interest.Revealing the mechanism of acrolein formation is o...Propylene epoxidation by H_(2)and O_(2)to propylene oxide(PO)over the Au-Ti bifunctional catalysts,as an ideal reaction for PO production,has attracted great interest.Revealing the mechanism of acrolein formation is of great importance for understanding the mechanism of molecular oxygen activation and the formation of hydroperoxo species on the Au sites.Here,we investigate the reaction mechanism of propylene oxidation to acrolein on the Au/uncalcined TS-1(Au/TS-1-B)catalyst through a combination of multiple characterization,H_(2)/D_(2)exchange,kinetics experiment,and modeling.The Ti sites are found to be non-essential to acrolein formation.Moreover,the acrolein formation on the Au/TS-1-B catalyst is confirmed to be promoted by H_(2)through hydroperoxo species formation,which includes two main steps:propylene dehydrogenation to*C_(3)H_(5)with the aid of*OOH species,and*C_(3)H_(5)oxidation by*OOH to acrolein.The latter step is determined to be the rate-determining step because the corresponding kinetics model gives the best description for experimental results.This work not only provides kinetics insights for the propylene hydro-oxidation to acrolein on the Au-Ti bifunctional catalysts,but also facilitates the rational design of Au catalysts with high activity and selectivity in the direct propylene epoxidation with H_(2)and O_(2).展开更多
基金supported by the National Natural Science Foundation of China(22208093,22038003,22178100,and 21922803)the Ministry of Science and Technology of the People's Republic of China under the Research Fund for National Key R&D Program of China(2021YFA1501403)+2 种基金the Program of Shanghai Academic/Technology Research Leader(21XD1421000)the Shanghai Science and Technology Innovation Action Plan(22JC1403800)the Innovation Program of the Shanghai Municipal Education Commission.
文摘Immobilizing highly dispersed Au nanoparticles onto titanium silicalite-1(TS-1)by a simple impregnation method under light is still a challenging task.In this work;a high photostable Au precursor protected by thiol ligands was firstly synthesized;and the as-prepared Au precursor displayed excellent stability under light for over 30 days;while the Au precursor without thiol ligands formed precipitates after just 2 h under light.Subsequently;the Au precursor protected by thiol ligands was immobilized on the external surface of uncalcined TS-1(i.e.;TS-1-B)by the incipient wetness impregnation method(IWI method)to prepare Au/TS-1-B catalyst.The activity of as-prepared Au/TS-1-B catalyst in the hydro-oxidation of propane to acetone was 1.4 times higher than that of the catalyst prepared by the deposition-precipitation urea method(DPU method).The structures of the Au/TS-1-B catalysts prepared by different methods were analyzed by multiple characterizations.Compared to the Au/TS-1-B catalyst prepared by the DPU method;the Au/TS-1-B catalyst synthesized by the IWI method exhibited a narrower size distribution of Au nanoparticles and had more small Au particles(<2 nm);which is the main reason for its superior activity.Additionally;the effects of gold loadings;reaction temperature and Si/Ti molar ratio on the catalytic performance of the Au/TS-1-B catalyst prepared by the IWI method were also investigated.In addition;the Au/TS-1-B catalyst prepared by the IWI method also exhibited excellent stability for over 140 h.
基金financially supported by the Research Fund for National Key R&D Program of China(No.2021YFA1501403)the National Natural Science Foundation of China(Nos.22038003,21922803,22178100,and 22208094)+2 种基金the Program of Shanghai Academic/Technology Research Leader(No.21XD1421000)the Shanghai Science and Technology Innovation Action Plan(No.22JC1403800)the Innovation Program of the Shanghai Municipal Education Commission.
文摘Propylene epoxidation by H_(2)and O_(2)to propylene oxide(PO)over the Au-Ti bifunctional catalysts,as an ideal reaction for PO production,has attracted great interest.Revealing the mechanism of acrolein formation is of great importance for understanding the mechanism of molecular oxygen activation and the formation of hydroperoxo species on the Au sites.Here,we investigate the reaction mechanism of propylene oxidation to acrolein on the Au/uncalcined TS-1(Au/TS-1-B)catalyst through a combination of multiple characterization,H_(2)/D_(2)exchange,kinetics experiment,and modeling.The Ti sites are found to be non-essential to acrolein formation.Moreover,the acrolein formation on the Au/TS-1-B catalyst is confirmed to be promoted by H_(2)through hydroperoxo species formation,which includes two main steps:propylene dehydrogenation to*C_(3)H_(5)with the aid of*OOH species,and*C_(3)H_(5)oxidation by*OOH to acrolein.The latter step is determined to be the rate-determining step because the corresponding kinetics model gives the best description for experimental results.This work not only provides kinetics insights for the propylene hydro-oxidation to acrolein on the Au-Ti bifunctional catalysts,but also facilitates the rational design of Au catalysts with high activity and selectivity in the direct propylene epoxidation with H_(2)and O_(2).
