Integrated thermodynamic, experimental, techno-economic, and environmental assessment of hydrogen production via combined steam and dry reforming of methane

Combined steam and dry reforming of methane (CSDRM) enables CO 2 utilization and flexible syngas production. However, process-level evaluations often rely on thermodynamic equilibrium and do not adequately represent kinetic limitations. This study integrated thermodynamic screening, experiments at 700 °C with a Ni/γ-Al₂O₃ catalyst, and techno-economic analysis and life cycle assessment based on Aspen Plus. Thermodynamic screening indicated that increasing the oxidant-to-CH 4 ratio reduced the equilibrium tendency for carbon formation, whereas a ratio of 2 favored syngas production. Based on this observation, three hydrogen-based scenarios were compared: ratio 2 (Case 1), ratio 3 (Case 2), and a steam methane reforming benchmark (Case 3). Case 1 had the lowest levelized cost of hydrogen and global warming potential, at 3.05 USD/kg-H 2 and 2.45 kg CO 2 -eq/kg H 2, respectively, compared with 3.53 USD/kg-H 2 and 15.35 kg CO 2 -eq/kg H 2 for Case 3. These advantages arose mainly from in-process CO 2 consumption and credits from by-product CO. Case 2 showed higher values of 3.40 USD/kg-H 2 and 3.83 kg CO 2 -eq/kg H 2 , respectively. Case 1 showed more favorable economic and environmental performance, while the higher oxidant input in Case 2 increased separation and utility burdens.