Au-supported 13X-type zeolite(Au/13X)was synthesized using a common deposition-precipitation(DP)method with a solution of sodium carbonate as a precipitate agent.Further testing was conducted to test for catalytic oxi...Au-supported 13X-type zeolite(Au/13X)was synthesized using a common deposition-precipitation(DP)method with a solution of sodium carbonate as a precipitate agent.Further testing was conducted to test for catalytic oxidation of CO.A study was conducted on the effects of different preparation conditions(i.e.,chloroauric acid concentration,solution temperature,pH of solution,and calcinations temperature)on Au/13X for CO oxidation.In respect to the catalytic activity,the relationship between different the preparation conditions and gold particles in 13X zeolite was analyzed using X-ray diffraction,TEM and XPS.The activity of Au/13X catalysts in CO oxidation was dependent on the chloroauric acid concentration.From XRD results,a higher chloroauric acid concentration induced larger gold nanoparticles,which resulted in lower catalytic activity.Results revealed that higher temperatures induced higher Au loading,homogeneous deposit,and smaller gold clusters on the support of 13X,resulting in higher CO activity.Furthermore,a pH of 5 or 6 generated greater amounts of Au loading and smaller Au particles on 13X than at a pH of 8 or 9.This may be a result of an effective exchange between Au(OH)_(2)Cl_(2)^(-)and Au(OH)_(3)Cl^(-)on specific surface sites of zeolite under the pH’s 5 and 6.The sample calcined at 300℃showed the highest activity,which may be due to the sample’s calcined at 200℃inability to decompose completely to metallic gold while the sample calcined at 400℃had larger particles of gold deposited on the support.It can be concluded from this study that Au/13X prepared from a gold solution with an initial chloroauric acid solution concentration of 1.5×10^(-3)mol·L^(-1)gold solution pH of 6,solution temperature of around 90℃,and a calcination temperature of 300℃provides optimum catalytic activity for CO oxidation.展开更多
基金This work was financially supported by the National Natural Science foundation of China(Grant No.20777005)Beijing Natural Science Foundation Program(No.8082008)Beijing Municipal Foundation for Excellent Person of Ability(No.20071D0501500210).
文摘Au-supported 13X-type zeolite(Au/13X)was synthesized using a common deposition-precipitation(DP)method with a solution of sodium carbonate as a precipitate agent.Further testing was conducted to test for catalytic oxidation of CO.A study was conducted on the effects of different preparation conditions(i.e.,chloroauric acid concentration,solution temperature,pH of solution,and calcinations temperature)on Au/13X for CO oxidation.In respect to the catalytic activity,the relationship between different the preparation conditions and gold particles in 13X zeolite was analyzed using X-ray diffraction,TEM and XPS.The activity of Au/13X catalysts in CO oxidation was dependent on the chloroauric acid concentration.From XRD results,a higher chloroauric acid concentration induced larger gold nanoparticles,which resulted in lower catalytic activity.Results revealed that higher temperatures induced higher Au loading,homogeneous deposit,and smaller gold clusters on the support of 13X,resulting in higher CO activity.Furthermore,a pH of 5 or 6 generated greater amounts of Au loading and smaller Au particles on 13X than at a pH of 8 or 9.This may be a result of an effective exchange between Au(OH)_(2)Cl_(2)^(-)and Au(OH)_(3)Cl^(-)on specific surface sites of zeolite under the pH’s 5 and 6.The sample calcined at 300℃showed the highest activity,which may be due to the sample’s calcined at 200℃inability to decompose completely to metallic gold while the sample calcined at 400℃had larger particles of gold deposited on the support.It can be concluded from this study that Au/13X prepared from a gold solution with an initial chloroauric acid solution concentration of 1.5×10^(-3)mol·L^(-1)gold solution pH of 6,solution temperature of around 90℃,and a calcination temperature of 300℃provides optimum catalytic activity for CO oxidation.
