Numerical investigation and microkinetic modelling of high-temperature water-gas shift reaction for hydrogen production using iron-based catalysts

The advancement of the hydrogen economy worldwide has facilitated the production of hydrogen from various resources. The water-gas shift reaction (WGSR) serves as a critical intermediate step for hydrogen enrichment and CO reduction in syngas derived from carbon-based hydrogen production. This paper presents a numerical investigation into the kinetic modelling of high-temperature WGSR using an iron-based catalyst in a reactor equipped with a Ni membrane. The study employs the Podolski et al. kinetic model with a 93% Fe₂O₃/7% Cr₂O₃ catalyst to evaluate the impact of temperature and the CO/H₂O molar ratio on the overall reaction performance. Results indicate that an increase in temperature leads to a decrease in reactant conversion. To achieve optimal CO conversion and H₂ generation, a CO/H₂O molar input ratio of 1 is necessary. On the other hand, a microkinetic model for WGSR based on the formate mechanism over an iron-based catalyst is proposed. This comprehensive model includes seven adsorbed species and encompasses 18 elementary-step forward reactions. The developed model also enables the evaluation of temperature effects on surface coverage. Key intermediates identified in the model include OH* and HCOO* species. Additionally, it was determined that CO activation is more favorable at high temperatures.