A molten salt-mediated biomass gasification process for high-yield hydrogen production with in situ carbon capture: experiments, simulation and ANN prediction

Abstract

Biomass gasification is a promising technology for green hydrogen production. In this study, a molten salt-mediated biomass gasification process with in situ carbon capture for hydrogen-rich syngas production is proposed and analyzed via experiments, process simulation and ANN modeling. The process utilizes molten salts as a solar energy carrier, with the entire system’s heat requirements fulfilled through solar energy, thereby increasing the gas yield per unit biomass. CaO is added to the process to facilitate in situ CO₂ capture and enhance the WGS reaction, enabling simultaneous CO₂ sequestration and increased hydrogen production in the syngas. Key operational parameters such as temperature, calcium-to-carbon (Ca/C) molar ratio, and steam-to-carbon (S/C) molar ratio are experimentally investigated. Results indicate a hydrogen composition of 68.67 vol% at 600 °C, with optimal Ca/C and S/C ratios of 1:1.5 and 1:1, respectively. A quasi-steady-state model developed in Aspen Plus is verified with experimental data, and a full loop model identifies an optimal molten salt-to-biomass (M/B) mass ratio of 2.40. Additionally, an artificial neural network was employed to predict the relationship between key operational parameters and hydrogen yield. The best-performing model, ANN12, achieved a high coefficient of determination (R² = 0.99587). This process allows for simultaneous hydrogen production and carbon capture, offering an efficient method for green hydrogen generation with negative carbon emissions.