Rdot Analysis Based Reduced Rate Expression for Water Gas Shift Reaction Over Nickel

ABSTRACT

Water gas shift reaction (WGS) is a prominent side reaction encountered generally in biomass‐based reforming and pyrolysis reactions using Nickel (Ni) based catalysts. Comprehensive understanding of these reactions involves kinetics of WGS which often is mostly based on power law‐based modelling approaches. Though power‐law models predict the experimental trend, these models lack thermodynamic consistency and mechanistic insights. In this context, this study is aimed at the development of comprehensive rate expression for WGS over Ni using Rdot approach and validation of the same for different WGS experimental conditions in the literature. In this study, WGS was assumed to proceed via carboxyl mechanism with 7 step microkinetic model proposed for the same. The microkinetic model is validated through Chemkin and Rdot analysis has been used to obtain a comprehensive rate expression. This rate expression was further reduced using MARI approximations. The validity of the rate expressions was performed using isothermal PFR approach. Based on the simulations, it was seen that these rate expressions were able to match the experimental trend and Chemkin predictions to reasonable accuracy thus validating the modelling approach.