Enhanced hydrogen production via steam gasification of wood-plastic composites over steel slag-supported Ni catalysts: Unveiling the intrinsic CaO-Fe2O3 synergy

Wood-plastic composites (WPC) are generated in growing amounts and remain difficult to recycle, posing significant challenges for sustainable resource recovery. This study proposes a hydrogen (H 2 ) production strategy via steam gasification of WPC, employing steel slag (SS) as a multifunctional catalyst to improve gas yield and syngas quality. To elucidate the catalytic role of SS, its performance in WPC steam gasification was evaluated and compared with those of individual CaO, individual Fe 2 O 3 , and a physically mixed CaO-Fe 2 O 3 in a lab-scale fixed-bed reactor. Furthermore, the impact of varying Ni loadings, reaction temperatures, and catalyst-to-feedstock (C/F) ratios were assessed, along with catalyst reusability tests. The results demonstrate that SS promotes steam gasification reaction through the intrinsic synergy between Fe 2 O 3 and CaO, where Fe 2 O 3 facilitates oxygen transfer and the water-gas shift (WGS) reaction, while CaO enhances in situ CO 2 adsorption. Consequently, compared with non-catalytic gasification, the H 2 selectivity increased from 21.67 to 31.50 vol%, while the CO 2 selectivity decreased from 29.53 to 26.89 vol%, accompanied by an increase in overall gas yield. The incorporation of Ni further led to a substantial enhancement in gas yield and H 2 selectivity, demonstrating the effectiveness of waste-derived SS as a catalytic material for sustainable H 2 -rich syngas production. Additionally, higher reaction temperatures and C/F ratios resulted in increased gas yield and H 2 selectivity.