CuO-Co_2O_3/La-Y-Al_2O_3催化剂CO氧化活性的实验研究

STUDY ON PERFORMANCE OF CuO-Co_2O_3/La-γ-Al_2O_3 CATALYSTS

考察了不同Cu与Co原子量比(Cu/Co)对金属氧化物负载量为7％(质量)的Cuo-Co_2O_3/La-Y-Al_2O-3催化剂CO氧化活性和水热稳定性的影响.应用XPS,XRD和BET比表面测定方法对催化剂进行了表征.结果表明,催化剂的CO氧化活性随着Cu/Co的减小而减少.但经过水热处理后,催化剂的活性出现某些变化:Cu/Co>0.43时,催化剂CO氧化活性降低;Cu/Co<0.43时,催化剂CO氧化活性提高.XPS和XRD测定结果表明,CuO-Co_2O_3/La-r-Al_2O_3催化剂中形成的CoAl_2O_4尖晶石结构在水热处理后部分受到破坏,且Co元素在催化剂表面富集.

A series of CuO-Co2O3/La-γ-Al2O3 catalysts with different Cu/Co atomic ratios and the same loading of metallic oxides were prepared by impregnating La-γ-Al2O3 with aqueous solution of copper and cobalt nitrate. The activity of catalysts for Co oxidation and bydrothermal stability were determined in a flow reactor. XPS. XRD and BET method was used to characterize the catalysts. The results obtained showed that the activity of catalysts decreases with the decrease of Cu/Co atomic ratio in the catalysts. After the catalysts were treated by a mixture of water vapor and nitrogen at 760℃ for 8 hours, the activity of the catalysts with Cu/Co atomic ratio lower than 0.45/1 is better than that of the catalysys before hydrothermal treatment. Examination with XPS and XRD methods indicated that after hydrothermal treatment, the CoAl2O4 crystal grains in CuO-CozOs/La-γ-Al2O3 catalysts become smaller, and the element of Co in CoAl2O4 crystals was shifted to the surface of catalysts and exists as Co oxides.