Microkinetic Modeling and Reduced Rate Expression of the Water–Gas Shift Reaction on Nickel

Abstract

The development of a first-principles-based microkinetic modeling of the water–gas shift (WGS) reaction on nickel surfaces is presented. The surface reaction mechanism consists of 19 elementary reversible steps among 10 adsorbates. Density functional theory (DFT) was used to calculate the binding energies and transitions states of all adsorbates and reactions on Ni(111) and Ni(211) surfaces [Catapan; DFT study of the water–gas shift reaction and coke formation on Ni (111) and Ni (211) surfaces. J. Phys. Chem. C 2012, 116, 20281−20291]. Thermodynamic consistency of the DFT-predicted energetics was taken into account in the construction of the kinetic mechanism. Lateral interactions between adsorbates were calculated via DFT and included in the microkinetic modeling using a hierarchical approach. The model predictions compare well with experimental results on Ni/Al2O3 reported in the literature, reproducing CO conversion, apparent activation energy, and reaction orders for CO and H2O. A reduced microkinetic...