Effect of Alkylaluminum Activators on Ethylene Trimerization Based on 2,5-DMP/Cr(III)/TCE Catalyst System

• Published in: Chinese journal of chemistry 2011-06, Vol.29 (6), p.1149-1153
• Main Authors: Jiang, Tao, Ji, Rongxin, Chen, Hongxia, Cao, Chengang, Mao, Guoliang, Ning, Yingnan
• Format: Article
• Language: English
• Subjects: cocatalyst; coordination modes; ethylene; oligomerization
• ISSN: 1001-604X; 1614-7065
• DOI: 10.1002/cjoc.201190215

Ethylene trimerization toward 1‐hexene catalytic system with 2,5‐dimethylpyrrole (2,5‐DMP)/Cr(III)/alkylaluminum/tetrachloroethane (TCE) was investigated. The effects of various cocatalysts on catalytic activity and product selectivity were discussed. The results showed that triethylaluminum (TEA), trimethylaluminum (TMA), tri‐n‐hexylaluminum (TNHA) and tri‐isobutylaluminum (TIBA) were all effective cocatalysts for ethylene trimerization toward 1‐hexene. 2,5‐DMP/Cr(III)/TEA/TCE catalytic system afforded the best results for ethylene trimerization, while reducing the level of by‐product formation. Some specific interaction modes of alkylaluminum with active Cr species in the catalytic cycle were proposed to explain the effect of cocatalyst on catalytic activity and 1‐hexene selectivity. The effects of various cocatalyst on the catalytic performance in ethylene trimerization reactions were studied using a homogeneous 2,5‐dimethylpyrrole (2,5‐DMP)/Cr(III)/alkylaluminum/tetrachloroethane (TCE) catalyst system. The results show that the cocatalyst has significant effect in improving selectivity toward 1‐hexene. Some specific interaction modes of alkylaluminum with active Cr species in the catalytic cycle were proposed.