Evaluating a reaction kinetic model for steam reforming: a microscopic reversibility analysis

Steam methane reforming (SMR) is the most commonly used method for hydrogen and syngas production. Hydrogen plays a vital role in generating clean energy for a sustainable future, as well as in many different industries. Syngas, a mixture of hydrogen and carbon monoxide, is a crucial feedstock in the production of synthetic fuels and various chemicals, further enhancing the industrial importance of SMR. Besides its significance, the SMR has an environmental impact, especially in terms of carbon emissions. Improving efficiency and minimizing the environmental impact of the SMR is essential for achieving a cleaner and greener environment. This work aims to evaluate the established reaction kinetic model formulated by Xu and Froment, encompassing the principal steam methane reforming (SMR) reaction and side processes, including the water-gas shift (WGS) and carbon dioxide methanation. The proposed model consists of specific rate expressions and a set of parameters for each reaction. However, as hypothesized in this work, according to the principle of microscopic reversibility, only two of these reactions should have independent equations and parameter sets. In this work, the kinetic model is analyzed in-depth, and adjustments are made to ensure its compliance with the microscopic reversibility. In addition, a MATLAB model has been developed for the simulation of the reaction network and thermodynamics of the CO2 methanation reaction and validated against experimental data through simulations. In order to represent the reaction network and verify the predictive accuracy of each two-reaction model, the outcomes are compared. Parameter-fitting techniques are implemented for each reaction pair to optimize the reaction kinetics under varying conditions of temperature, pressure, and space-time. The statistical significance of estimated parameters has been evaluated to confirm the suitability of the two-reaction pairing model. From the attained results it has been concluded that the revised kinetic model develops a better understanding of reaction mechanisms in SMR and fosters more efficient, low-emission hydrogen and syngas production methods.