Steam, dry and autothermal methane reforming for hydrogen production: A thermodynamic equilibrium analysis

Environmental issues of fossil fuels use in energy systems are boosting research in the field of H-2 generation. Although steam reforming is the most well-established process for H-2 production, alternative thermochemical routes are emerging. The paper aims to compare three reforming processes: steam methane reforming, dry methane reforming and autothermal methane reforming. To this end, a thermodynamic equilibrium model is developed and validated via comparison with literature data. The influence of operating conditions on the performance of the reforming options is investigated, addressing chemical and energy-related aspects. Regarding the former, attention is focused on H-2 yield and selectivity over CO and CO2. From the energy viewpoint, performance indices investigated include the lower heating value of syngas, the reformer thermal power requirement and the chemical energy increase of fuel at the reformer exit. An H-2 production efficiency is also evaluated to directly compare steam, dry and autothermal methane reforming. The study revealed that moderate pressures and oxidant-to-methane ratios allow finding the best compromise between H-2 production and process efficiency in all investigated reforming options; under these conditions, steam methane reforming performs better than dry methane reforming; however, when the reformer operates under autothermal conditions, the performance of dry methane reforming approaches that of steam methane reforming.