The Effect Of Co-Catalysts In Ethylene Trimerization Catalytic Systems

Synthesis of high selectivity and high activity of 1-hexene catalyst system is an important direction. The chromium-based catalysts is a major developed ethylene trimerization catalyst system. Current research in the field mainly concentrated the reaction mechanism of the chromium-based catalyst system which selectives catalytic trimerization of ethylene to generate 1-hexene, as well as the impact of the ligand structure on the chromium-based catalyst system, however, these external factors which can be able to restrict the product of 1-hexene, such as cocatalyst, for comprehensive study of the system is still rarely reported.Domestic 1-hexene research in the subject, based on the reaction mechanism of ethylene trimerization, the role of five kinds cocatalysts will be investigated in the [Cr(2-EH)3/2,5-DMP/cocatalyst/TCE] quaternion selectivity catalytic ethylene trimerization for 1-hexene catalyst systems. Using gas chromatography/mass spectrometer analysis the qualitative and quantitative product of ethylene trimerization. Mainly to study their impact on 1-hexene selectivity and catalyst activity has been a series of valuable results and conclusions.The focus of this thesis investigated five cocatalysts, they are triethyl aluminum, trimethyl aluminum, tri-isobutyl aluminum, tri-hexyl aluminum and methylaluminoxane. The 1-hexene formation selectivity of the five alkylaluminiums are all good. In the quaternion catalyst system, when using triethyl aluminum as cocatalyst, we can get higher 1-hexene selectivity, and the catalyst activity was significantly higher than other alkylaluminium's. When using trimethyl aluminum and tri-isobutyl aluminum as cocatalysts, we can get higher 1-hexene formation selectivity than triethyl aluminum's. But when using tri-hexyl aluminum and methylaluminoxane as cocatalysts, the 1-hexene formation selectivity is opposite.