Kinetic models discrimination for the high pressure WGS reaction over a commercial CoMo catalyst

Abstract

A mechanistic kinetic model has been study to describe the bench scale water-gas shift reaction over a commercial presulfided CoMo catalyst using an industrial coal-derived gas feed. A rigorous kinetic network has been considered on the basis of formate, associative and direct oxidation mechanisms. Kinetic models were derived by using LHHW formalism and steady-state approximation for reaction intermediates. Kinetic parameters were estimated by nonlinear regression of the experimental data using the Marquardt–Levenberg algorithm. The WGS kinetic data were measured by experiments over a wide range of reaction conditions and comparisons for various rate equations were also established. A preliminary discrimination resulted in the necessity of rewrite models as a unique parameter models. The model based on direct oxidation mechanism successfully predicted the CO 2 formation within the range of experimental conditions (high pressure and temperature). WGS rate expressions based on the regenerative process (oxidation-reduction) with the assumption that CO 2 desorption reaction can be regarded as the rate determining step were found to be the best.