关键词: 催化剂, EPR, Cu²⁺, 配位, 氧氯化

Abstract: The EPR spectra of CuCl₂ and a series of CuCl₂/γ-Al₂O₃ samples have been compared, and fitted using the theory formula of EPR powder spectra. The results suggest that there are two distinct coordination sites for Cu²⁺ ions in the samples of fresh catalyst at least, which are both different from that of Cu²⁺ ions in CuCl₂ or in CuCl₂· 2H₂O. The EPR parameters obtained by fitting show that one of them might be due to the site with plenty of coordinate O^2-, and the other might be due to the site which is rich in coordination Cl^-. Their propotions varies with the Cu contents in the samples. In the catalyst with low CM content, Cu²⁺ ions prefer to go into the cavities formed by O^2- coordination-unsaturated on the surface of γ-Al₂O₃ in monolayer, and to separate from each other while dispersing. The intensity data of EPR are in agreement with this fact also. But in the catalyst with higher Cu load, which has higher catalytic activity, including its specific activity, much more Cu²⁺ ions exist in Cu-Cl coordination manner. This fact implies that Cu²⁺ ions with more Cl neighbors in the catalyst might be correlative to catalytic activity of oxychlorination.

Key words: Catalyst, Cu²⁺ Coordination, EPR, Oxychlorination