制备了高分散的 Ag/SiC 和 Al2O3 修饰的 Ag/SiC 催化剂,并用于乙烯环氧化反应.结果显示,Al2O3 修饰的 Ag/SiC催化剂对乙烯的转化率显著提高,但环氧乙烷的选择性急剧降低.进一步研究发现,在反应过程中乙烯吸附在 SiC表面;O2 在 Ag 表面解离后,活性 O 物种溢流到 SiC 表面参与环氧化反应.Al2O3 修饰后改变了Ag的电子性质,抑制了活性O物种在SiC表面的迁移,导致反应性能的改变.该工作为乙烯环氧化催化剂的设计提供了一定的参考.
Catalytic performances of Ag/SiC and Ag/Al2O3-SiC catalysts for ethylene epoxidation
Highly dispersed Ag/SiC and Al2O3 modified Ag/SiC catalysts were prepared and employed for ethylene epoxidation.The results showed that the conversion of ethylene was significantly im-proved after Al2O3 modification,but the selectivity of ethylene oxide was sharply reduced.Further studies revealed that ethylene was adsorbed on SiC surface in the reaction.After O2 was dissociated on the Ag surface,the active O species spilled over to SiC surface to participate in the epoxidation reac-tion.The Al2O3 modification altered the electronic properties of Ag and inhibited the migration of ac-tive O species on SiC surface,resulting in the change of ethylene epoxidation performances.This work provides some reference for the design of catalysts for ethylene epoxidation.
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