B型银催化剂上乙烯环氧化宏观动力学研究

Macrokinetics of Ethylene Epoxidation over B-Type Silver Catalyst

针对B型银催化剂,提出以表面反应为控制步骤、乙烯与一个活性中心位上非解离吸附氧发生环氧化反应和乙烯与相邻多个活性中心位上解离吸附氧发生深度氧化反应的乙烯环氧化反应机理;考虑到抑制剂1,2-二氯乙烷的竞争吸附作用,引入有效总活性位点覆盖率概念,构建包含1,2-二氯乙烷影响因子项的乙烯环氧化宏观动力学模型。采用无梯度反应器进行B型银催化剂上乙烯环氧化合成环氧乙烷的宏观动力学实验,以单纯形优化方法进行非线性参数估值,建立了与实验数据良好吻合的B型银催化剂上乙烯环氧化宏观动力学模型。

Possible reaction mechanism for the epoxidation of ethylene to ethylene oxide over the B-type silver catalyst was investigated,in which it was proposed that with the surface chemical reactions as rate-controlling step,the epoxidation reaction would occur between ethylene and non-dissociated adsorbed oxygen on an active site,and the deep oxidation would occur between ethylene and dissociated adsorbed oxygenon the adjacent active sites. Considering the strong competitive adsorption of 1,2-dichloroethane inhibitor,a concept for effective surface coverage was presented and the macro-kinetic model for the ethylene epoxidation over the B-type silver catalyst was established. Macro-kinetic experiments were carried out in a gradientless reactor. And the parameters of the macro-kinetic model were estimated by means of the simplex optimization method. Statistical test showed that the macro-kinetic model established for the B-type silver catalyst agreed well with the experimental results.