ZrO_2对Cu/CeO_2-ZrO_2水煤气变换催化剂结构、性能的影响

Effects of ZrO_2 Content on Structure and Properties of Cu/CeO_2-ZrO_2 Catalysts for Water-Gas Shift Reaction

采用共沉淀法制备了系列Cu/CeO2-ZrO2水煤气变换(WGS)催化剂。用N2物理吸附、XRD和H2-TPR手段研究了ZrO2组分对催化剂的织构、物相、还原性能、热稳定性以及WGS反应活性的影响。结果表明,添加ZrO2组分均提高了催化剂的比表面积,且随ZrO2含量的增加,孔径逐渐向小孔集中,即大孔数量减少,小孔数量增加,最可几孔径移至1.9 nm左右,并逐渐增强。ZrO2的加入能有效地抑制CeO2晶粒的长大,同时适量的ZrO2可使铜铈基催化剂在WGS反应过程中保持较高的Cu分散度,从而使其具有较高的活性和稳定性。当催化剂中ZrO2含量为10%,反应温度为200℃时,WGS反应中CO的转化率达到73.7%。

Cu/CeO2-ZrO2 catalysts for water-gas shift （WGS） reaction were prepared by co-precipitation method, and the influence of ZrO2 content on the catalytic structure and properties was investigated by using N2 physical adsorption, XRD and H2-TPR. The results indicate that the BET surface areas of the catalysts are increased in various degree due to the existence of ZrO2. With increasing of ZrO2 content, the apertures are centralized to small pores gradually, that is to say, the amount of big pores decreases and the amount of small pores increases. The pore distributed about 1.9 nm is increased with ZrO2 content. Modified ceriasupported copper catalysts with ZrO2, can availably restrain ceria crystal particles growing and doped appropriate ZrO2 can keep higher copper dispersion in the course of catalyzing WGS reaction process, which both lead to higher catalytic activity and thermal stability. When ZrO2 content is 10%, Cu/CeO2-ZrO2 catalyst exhibits higher activity for WGS reaction, with 73.7% CO conversion at 200 ℃.