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

Abstract

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.