Hydrogen production by membrane assisted methanol steam reforming: An integrated kinetic and Pd-membrane model

Hydrogen is a promising clean energy carrier for fuel-cell transportation and stationary power systems, and methanol is an attractive liquid hydrogen source because it is easily stored, widely distributed, hydrogen-rich, and potentially renewable as biomethanol. However, conventional methanol steam reforming is limited by thermodynamic equilibrium, incomplete low-temperature conversion, and difficulty in achieving high hydrogen yield and purity simultaneously. This study develops an integrated kinetic membrane–thermal model for methanol steam reforming in a Pd-based membrane reactor. The novelty lies in coupling Langmuir Hinshelwood reaction kinetics, plug-flow species balances, Pd-membrane hydrogen permeation, carrier-gas dilution, pressure-driven hydrogen extraction, and energy balance requirements within one framework. Unlike previous studies that treated kinetics, membrane transport, operating variables, or thermal effects separately, the model evaluates methanol conversion and hydrogen recovery simultaneously under compact reformer conditions. The predictions were validated against published experimental data for temperature and pressure-dependent methanol conversion, showing good agreement with reported trends. Results show that performance is governed by reaction permeation coupling. Increasing temperature and reaction pressure enhance conversion and hydrogen recovery by improving kinetics and transmembrane driving force. Permeate side carrier gas dilution further promotes hydrogen extraction, while the optimum performance occurs near S/C = 1. The model provides design guidance for compact methanol reformers operating below 300°C.