Hydrogen Production from Municipal Solid Waste Gasification: Aspen Plus Simulation and Box–Behnken Optimisation

Municipal Solid Waste (MSW) gasification presents a promising pathway for low-carbon bio-hydrogen production. However, MSW is underrepresented as a feedstock in the gasification literature due to its heterogeneity, and fewer studies have leveraged Box–Behnken experimental design in gasification simulation studies or investigated the interaction between equivalence ratio and steam–feed ratio. This paper develops a thermodynamic equilibrium model in Aspen Plus® (V14) to simulate oxy-steam gasification of MSW derived from the Phyllis database, with subsequent optimisation using Box–Behnken Design. Sensitivity results confirm literature trends, with hydrogen yield generally increasing with gasification temperature and steam–feed ratio up to an optimum threshold, while an increasing equivalence ratio suppresses hydrogen formation. An optimum hydrogen volume fraction of 51.77% in the syngas composition was achieved at a gasification temperature of 873 °C, equivalence ratio of 0.3, and a steam-to-feedstock ratio of 0.5. The study revealed a comparatively smooth response surface between equivalence ratio and steam–feed ratio, and a statistically insignificant effect of equivalence ratio on hydrogen formation in steam gasification. This provides new insight into gasification systems, whereby, within the investigated equivalence ratio (ER) ranges of 0.2–0.4, steam can effectively drive hydrogen-enhancing reactions, thereby reducing the relative importance of oxygen supply in oxy-steam gasification. The study could provide useful guidance on experimental design for hydrogen production through steam gasification.