Steric hindrance of ligand in Chevron-Phillips trimerization catalyst

To elucidate the effect of steric hinderance of dialkylpyrole type ligands on the potential energy surfaces of the reaction pathway in the landmark Chevron−Phillips ethylene trimerization system, a detailed theoretical study has been carried out by DFT method on an aluminum pyrrolyl chromium catalyst. In this respect reaction pathways for selective ethylene trimerization have been successfully located on the basis of the metallacycle mechanism using three different molecular models of A, B and C which mainly differ in the alkyl group of the pyrrole ligand (A, B and C correspond to dimethyl- diisopropyl- and ditert-buthylpyrrole, respectively). After calculating potential energy surface for the oligomerization reaction pathway, to quantify the steric role of the pyrrole ligand in 1-hexene selectivity, analysis of the buried volume in terms of steric maps was performed

Keywords:

Chevron-Phillips catalyst , Trimerization , DFT , Simulation