CeO_2-Al_2O_3负载金催化剂用于水煤气变换反应的催化活性

Preparation of ceria-alumina and catalytic activity of gold catalyst supported on ceria-alumina for water gas shift reaction

采用浸渍法和沉积-沉淀法制备了CeO2-Al2O3复合氧化物,比较了复合氧化物负载纳米金催化剂对水煤气变换反应的催化活性。通过N2物理吸附、XRD、TEM、H2-TPR等表征手段对复合氧化物及其负载金催化剂的物相和结构进行分析,发现复合氧化物的制备方法及其焙烧温度对其比表面积、孔结构及水煤气变换反应活性有明显的影响。与沉积-沉淀法相比,浸渍法制备的CeO2-Al2O3复合氧化物具有较大的CeO2晶粒尺寸,经500℃焙烧后再负载金,所得催化剂具有更高的活性,250℃时CO转化率可达78.1%。

Ceria-alumina composite oxides with different ceria loadings（5%,10%,20%,25%,and 30%） were prepared by impregnation method and deposition-precipitation method,respectively.Gold catalysts supported on these oxides were used to water gas shift reaction.All samples were characterized by nitrogen adsorption,X-ray diffraction（XRD）,transmission electron microscopy（TEM） and hydrogen temperature-programmed reduction（H2-TPR）.It is found that the preparation method and calcination temperature of ceria-alumina oxides have a marked influence on their surface areas,porous structures and the catalytic performances of supported gold catalysts for water gas shift reaction.Ceria-alumina oxides prepared with impregnation method gave larger ceria particle size and high catalytic activity than those prepared with deposition-precipitation method.Gold catalyst supported on 20%CeO2-Al2O3 oxide calcined at 500 ℃ showed the highest activity.CO conversion reached 78.1% at 250 ℃ and atmospheric pressure.