A novel hybrid reforming reactor for enhanced CO₂ conversion and hydrogen production: A CFD analysis

The use of hydrogen as an energy carrier has gained significant attention due to its environmentally friendly characteristics. Among various production methods, steam reforming of natural gas (CH₄) remains the most cost-effective and widely adopted technique. To enhance the efficiency and carbon utilization of this process, a novel hybrid steam and dry reforming reactor has been proposed, which utilizes the CO₂ produced from steam reforming within a dry reforming zone. In this study, a two-dimensional axisymmetric hybrid catalytic membrane reactor (CMR) model was developed for the production of pure hydrogen from natural gas, employing a Pd–Ru metallic membrane and a carbonate dual-phase membrane, integrated with Ni/Al₂O₃ and Rh/Al₂O₃ catalysts. A computational fluid dynamics (CFD) approach was employed to investigate the reactor’s performance in terms of methane conversion and hydrogen production under various operating conditions. These include reaction temperatures of 700, 800, 900, and 1000 K, a gas hourly space velocity (GHSV) of 1000 h⁻¹, and a sweep gas Reynolds number (Re) of 100. Simulation results revealed that the CMR achieved a high hydrogen permeation rate on the permeate (tube) side, along with a maximum CH₄ conversion of approximately 99.9% at 1000 K on the retentate side within the steam reforming zone. Furthermore, the reactor demonstrated effective syngas production with near-complete CO₂ reduction on the dry reforming side, where CO₂ concentrations at the reactor outlet approached zero at 1000 K. These findings highlight the promising potential of the hybrid combined membrane reactor (CMR) system for efficient hydrogen production and near-complete carbon utilization.