摘要
银催化剂是用于乙烯环氧化唯一的工业化催化剂.工业生产上,通常在原料气(C_2H_4,O_2,CO,N_2的混合气)中添加10^(-9)～10^(-6)mol的1,2-C_2H_4Cl_2,以改善催化剂的选择性.一般认为1,2-C_2H_4Cl_2在反应中分解的氯,以负离子状态强吸附于催化剂的银表面上.我们曾尝试用电子能谱仪分析催化剂吸附的氯,但由于它对氯的灵敏度很低,基本上观察不到.
Laser plasma mass spectrometry (LMS) was first time applied to cha racterize the species on heterogeneous catalysts. This method showed high sensitivity for the characterization of adsorbed Cl species on silver catalyst. The results demonstrated that the silver supported on α-Al2O3 could decompose the doping 1,2-C2H4C12 in the feed gas, the produced Cl species adsorbed on silver catalyst was of two types, the strongly chemisorbed and the weakly chemisorbed. These Cl species helped to improve the catalytic selectivity of silver catalyst. The results also showed that Cs+ doping in Ag catalyst favoured the stabilization of the weakly chemisorbed Cl species. The LMS technique is proved to be an effective means in this experiment, and therefore will find its way in the study of heterogeneous catalysis.
基金
青年科学基金
