Optimization of catalytic steam gasification for hydrogen production: response surface methodology approach

Abstract The current investigation delves into the process of the optimization of hydrogen production via catalytic steam gasification within a fixed-bed downdraft gasifier. This study optimized hydrogen-rich syngas production from biomass by using catalytic steam gasification in a fixed-bed reactor. Response surface methodology with a Box-Behnken design was employed to model the effects of the steam-to-biomass ratio (1–3), nanocatalyst loading (5–15 wt%), and airflow rate (20–40 L min−1) on syngas yield and hydrogen content. The derived quadratic model was highly significant, with optimization identifying an airflow rate of 30 L min−1, steam-to-biomass ratio of 3.0, and nanocatalyst loading of 5 wt% as the ideal conditions. Experimental validation under these parameters confirmed the excellent predictive capability of the model, yielding 1.69 m3 kg−1 of syngas with a high hydrogen content of 65.9% along with carbon monoxide of 13.2%, carbon dioxide of 8.6%, and methane of 1.3%. This represented a substantial enhancement over conventional air gasification, which produced only 1.52 m3 kg−1 syngas with 16.2% H2. The optimized catalytic steam-gasification process achieved a cold gas efficiency of 82.5% and a hydrogen yield of 108.8 g kg−1 of biomass, driven by the synergistic effect of steam and the nanocatalyst in promoting tar cracking and reforming reactions. The resulting syngas had a heating value of 11.49 MJ Nm−3. These results demonstrate that the response-surface-methodology-guided optimization of nanocatalytic steam gasification is a highly effective strategy for producing a high-quality, hydrogen-rich syngas, marking a significant improvement in process efficiency for sustainable energy applications.