Experimental and kinetic study of pressurized CO2 gasification of biomass chars

Pressurized CO₂ gasification of biomass represents an effective approach for the utilization of biomass and the reduction of CO₂ emissions. The impact of CO₂ partial pressure on the gasification kinetics of biomass chars was examined on a pressurized thermogravimetric analyzer at temperatures between 750 and 950 °C and elevated pressures (up to 1 MPa). The findings demonstrated that the gasification rates of corn stalk char (CSC), toonasinesis sawdust char (TSC), and rice husk char (RHC) exhibited an increase with rising CO₂ partial pressure. The reaction order exhibited variability with respect to CO₂ partial pressure, gasification temperature, and biomass type. The reaction order associated with biomass char exhibited a higher value at the elevated CO₂ partial pressure range (0.25–1.0 MPa) relative to the low CO₂ partial pressure range (0.025–0.1 MPa). The nth-order model was employed to elucidate the gasification behaviors of biomass chars. The results indicated that the modified random pore model was successfully applied to model the gasification of CSC and TSC. The grain model was effective in predicting the gasification behavior of RHC. The gasification rates of the three biomass chars were accurately predicted by the Langmuir-Hinshelwood model at both low and high CO₂ partial pressures. This study presents information on the effect of CO₂ partial pressure on biomass char gasification and methods for predicting biomass char gasification under pressurized conditions.