Mg-Al类水滑石负载金催化醇选择氧化中Mg/Al比例的影响

为研究Mg/Al比例对Mg-Al类水滑石(LDH)负载Au催化醇选择氧化的影响,采用共沉淀—水热晶化法合成了不同Mg/Al比的y Mg-Al LDH,采用液相还原法负载纳米Au颗粒.对样品进行XRD、N_2物理吸附、ICP-AES、AAS、TEM、CO_2-TPD、CO_2-In-situ DRIFTS和XPS等表征.在无附加碱条件下,Au/yMg-Al LDH催化剂催化1-苯乙醇选择氧化的催化活性随Mg/Al比增大呈现递增趋势,Au/4Mg-Al LDH活性最佳.载体表面弱碱性强度随Mg/Al比增大变化不大,弱碱位略有增多,对醇羟基脱氢有促进作用.载体层板Mg_3OH基团随Mg/Al比增大而增多有利于Au在层板边缘沉积,二者可形成有效协同,促进醇氧化过程进行.

Gold Supported on Mg-Al Layered Double Hydroxides for Selective Oxidation of Alcohols: the Effect of Mg/Al Mole Ratio

In order to investigate the effect of Mg/Al mole ratio on the catalytic performance of gold supported on Mg-Al layered double hydroxides (LDH) for the selective oxidation of alcohols,a series of Mg-Al LDH with various molar ratios of Mg/Al were prepared by the coprecipitation-hydrothermal crystallization method,on which Au nanoparticles were supported by the liquid-phase reduction method.The samples were characterized by XRD,N2 physical adsorption,ICP-AES,AAS,TEM,CO2-TPD,CO2-In-situ DRIFTS and XPS.The catalytic activities of Au/ yMg-Al LDH for the selective oxidation of 1-phenylethyl alcohol under base-free condition were increased with the increase of Mg/Al mole ratio,and Au/4Mg-Al LDH catalyst showed the best catalytic activity.The weak base strength of support surface was changed little with the increase of Mg/Al mole ratio,which promoted the dehydrogenation of alcoholic hydroxyl.The layered Mg3OH groups of the supports were increased with the increase of Mg/Al mole ratio,which was beneficial to the deposition of Au on the edges of LDH platelets.The effective synergy between the two promoted the oxidation of alcohols.