High thermal stable gold catalyst supported on La2O3 doped Fe2O3 for low-temperature CO oxidation

O6; La2O3 doped Fe2O3 support was prepared by co-precipitation method,and gold was loaded by deposition-precipitation.Thermal stability of gold catalyst was enhanced considerably by La2O3 doping.Even when calcined at 500℃ for 12 h,the catalyst doped with La2O3 could convert 90% of CO at 28.9℃,while the catalyst without La2O3 doping achieved 90% CO conversion at 43.5℃.Characterization techniques,such as N2 adsorption-desorption,X-ray diffraction (XRD),transmission electron microscopic (TEM) and thermogravimetry-differential scanning calorimeter (TG-DSC),were employed to investigate the structure and surface morphology of the catalysts.La2O3 doping retarded the collapse of mesoporous structure of catalysts during the calcination at high temperature,keeping higher specific surface area,smaller pore size and narrower pore distribution.After calcination at 500 ℃,the size of gold particles in Au/F2O3 was in the range of 6-10 nm and the size of support grains was 50-100 nm.However,the sizes of gold particles and support grains in Au/La2O3//Fe2O3 were remained in the ranges of 4-8 nm and 25-50 nm,respectively.The results of X-ray diffraction and thermal analysis also proved that La2O3 doping not only restrained the growth of gold particles,but also retarded the crystallization of support.