CuO/CeO_2催化剂在水煤气变换反应中的活性

采用共沉淀法、沉积沉淀法和等体积浸渍法制备了CuO/CeO2催化剂,考察了CuO负载量和H2还原温度对该催化剂水煤气变换反应活性的影响。采用XRD、N2吸附、UV-Vis DRS、TEM、H2-TPR技术对催化剂进行了表征。实验结果表明,共沉淀法制备的20%(w)CuO/CeO2催化剂在200℃下还原后表现出较高的水煤气变换反应活性,反应温度250℃时CO转化率为19.6%。CuO在催化剂中或高度分散在载体表面,或以大颗粒形式存在,还原后生成活性组分Cu2O和Cu0。CuO与CeO2之间的强相互作用能阻止CuO颗粒聚集,降低其还原温度;但过度还原会破坏这种相互作用,使催化剂活性降低。

Activity of CuO-CeO2 Catalyst in Water-Gas Shift Reaction

CuO/CeO2 catalysts were prepared by co-precipitation,deposition-precipitation and wetness impregnation methods,and characterized by means of N2adsorption,XRD,UV-Vis DRS,TEM and H2-TPR.The effects of the preparation method,CuO loading and reduction temperature on the activity of the CuO/CeO2 catalysts in water-gas shift(WGS) reaction were investigated.The results show that,after reduced at 200 ℃ by H2,the activity of 20%(w)CuO-CeO2catalyst prepared by co-precipitation method is the highest,the CO conversion of 19.6% at 250 ℃.In the unreduced catalyst,CuO either highly disperses on CeO2 surface or exists in the form of large grains.In the reduced and used catalysts,most of CuO is reduced into Cu2O and Cu0which are considered as the active sites in WGS reaction.The strong interaction between CuO and CeO2can inhibit the aggregation of the CuO particles and decrease its reduction temperature.However,the excess reduction can weaken the interaction and lead to the low activity.