Confinement-Driven Equilibrium Shifts in Steam Methane Reforming: A Monte Carlo Study in Zeolites

Abstract

Steam methane reforming (SMR) remains the dominant industrial route for hydrogen production, yet its highly endothermic nature demands elevated temperatures, resulting in substantial energy input and CO2 emissions. In this work, we investigate whether thermodynamic confinement within nanoporous materials can shift the SMR reaction equilibrium toward enhanced hydrogen yields at lower temperatures. Using Reaction Ensemble Monte Carlo simulations, we validate our molecular models against experimental bulk-phase data, and then systematically compare equilibrium behavior in large- and small-pore zeolites. Our results reveal that large-pore zeolite FAU, in both hydrophilic (NaX) and hydrophobic (pure silica) forms, fails to outperform the bulk. In contrast, the small-pore zeolite ITQ-12 significantly enhances hydrogen production under confinement. At 1 bar and 675 °C, ITQ-12 achieves hydrogen mole fractions comparable to those in the bulk at 825 °C, representing a 150 °C reduction in temperature with potential for considerable energy savings. Zeolite RHO, despite similar pore size, shows no such improvement, highlighting the critical role of channel geometry and topological confinement. These findings demonstrate that properly selected zeolite topologies can thermodynamically steer SMR towards more sustainable conditions. The framework established here offers a predictive route to identify nanoporous materials capable of enabling low-temperature hydrogen production.