微量1,2-二氯乙烷在乙烯环氧化中的作用及其吸附态的表征  

Effect of a Miero Quantity of 1,2-Dichloroethane on the Epoxidation of Ethylene and Characterization of the Adsorbed Species

作　　者：李基涛[1] 蔡丽芬[1] 

机构地区：[1]厦门大学化学系,物理化学研究所厦门361005

出　　处：《分子催化》1992年第2期113-119,共7页Journal of Molecular Catalysis(China)

摘　　要：在乙烯环氧化的原料气中添加微量的1,2-二氯乙烷能较大地提高乙烯环氧化的选择性。1,2-二氯乙烷在反应条件下能分解出氯,并以强、弱两种吸附态存在于催化剂的表面上。它们一方面抑制催化剂表面起深度氧化作用的氧原子的吸附强度和浓度,一方面又排斥反应生成的环氧乙烷,使它更快地脱附,从而减少环氧乙烷异构化的机会,提高乙烯环氧化的选择性。同时吸附在催化剂表面上的氯又与乙烯反应生成1,2-二氯乙烷。这样有机氯化物在催化剂表面上的分解消耗和反应生成达成平衡,以维持催化反应的持续进行。The ethyleneoxide(EO) selectivity can be increased considerably as a micro quantity of 1,2-C2H4C12 is added to the feed gas. The 1,2-C2H4Cl2 decomposed to Cl- during the epoxidation reaction. The Cl- was found to adsorb on the surface of Ag-catalyst in two modes-strongly and weekly adsorbed. It controls the intensity and concentration of the adsorbed oxygen atoms that play the key role in the complete oxidation of ethylene. It also expels the EO formed and thus decreases the chance of isomerization of EO. Meanwhile the Cl - adsorbed on the surface of Ag- catalyst can react with ethylene to form 1,2- C2H4C12. The Cl- can reach a steady state on the surface of the Ag-catalyst as 1,2-C2H4Cl2 is decomposed and formed so that the catalytic reaction progresses continuously.

关 键 词：二氯丙烷 吸附 乙烯 环氧化 

分 类 号：O623.121[理学—有机化学]