氧氯化催化剂的吸附和反应性能及其活性位置——Ⅰ.氧氯化催化剂对HCl、乙烯和氧的吸附性能及吸附位置

氧氯化催化剂对反应原料气氯化氢、乙烯和氧气的吸附性能依次减弱,对氯化氢的吸附最强烈,在实验条件下对氧则未发现有吸附。催化剂对氯化氧的吸附量与其CuCl_2含量密切相关,CuCl_2含量增加,氯化氢吸附量减少,表明氯化氢的吸附位置可能在催化剂的无CuCl_2覆盖的γ-氧化铝表面。催化剂的乙烯吸附量强烈地依赖于它的氯化锕含量、干燥程度等。实验结果表明,乙烯的吸附位置可能是催化剂表面的一些配位不饱和的铜离子,如四配位的铜离子。实验结果和络合-还原-氧化机理一致。

A Study on the Adsorption Behavior of Oxychlorination Catalyst

The adsorption of C_2H_4, HCl, O_2 on CuCl_2/γ-Al_2O_3 catalyst have been investi- gated by TPD. This catalyst can adsorb HC1 strongly. The adsorption amount of HC1 is correlative with Cu content in the catalyst. The adsorption amount decreases with increasing Cu content. It shows that the adsorption site of HCl on the catalyst might be on the surface of γ-Al_2O_3 where it is not covered by CuCl_2. The adsorption amount of C_2H_4 depends on Cu content, dryness of catalyst, and so on. The adsorption ratio (mol C_2H_4/mol Cu) declines with the increase of Cu content in catalyst. The results show that the adsorption sites might be Cu~(2+) with coordination unsaturated (such as coordination number 4).Adsorption of O_2 has not been found under the experimental conditions. The results are found to be in conformity with complex-redox mechanism for oxychlorination.