Kinetic modeling of hydroxycarbonylation of styrene using a homogeneous palladium complex catalyst

Abstract

Kinetics of hydroxycarbonylation of styrene using Pd(pyca)(PPh)(OTs)/PPh/TsOH/LiCl catalyst was investigated in a stirred batch reactor. The effects of catalyst, styrene, and water concentrations and the partial pressure of CO on the rate of hydroxycarbonylation as well as the concentration-time profiles have been investigated over a temperature range of 368-388 K. A unique observation was the induction period which was CO pressure dependent leading to lower rates of carbonylation at the start of the reaction. A molecular level description of the reaction mechanism (catalytic cycle) has been proposed to explain the observed trends. The results were found to be consistent with a mechanism based on a Pd-hydride complex as an active intermediate species. The proposed mechanism also captured the experimentally observed trends of induction period. The approach of microkinetic modeling used here does not require the assumption of a rate determining step and provides a good description of the complex trends observed with respect to reaction parameters over a wide range of conditions.