Experimental Study on Enhanced Gasification of Biomass and Simulation of a CO2 Adsorption Mechanism Based on a Modified Ca-Based Catalyst

This study examines the gasification properties of solid waste biomass under a steam atmosphere and the catalytic activity of Ca-based catalysts. Al and Ti metal-modified Ca-based catalysts, using calcium oxide (CaO) as a carrier, were prepared and analyzed. The gasification characteristics of straw biomass under various reaction conditions and with the addition of modified Ca-based catalysts were studied by using a fixed-bed gasification reaction device. The cycling performance of the catalysts before and after modification was also investigated. The CASTEP module of Materials Studio software facilitated a mechanistic simulation of CO 2 adsorption over the modified catalyst. This explored changes in stable configurations, particle density-of-state (PDOS) energy distributions, and bonding populations of both the modified and adsorbed catalysts. The findings demonstrate that the gasification performance of CaO significantly improved with the addition of Al metal. The H 2 yield was 347.7 mL/g at 800 °C, with a steam/biomass mass ratio of 1.5 and a Ca/C molar ratio of 1.0. The H 2 yield for CaAlO after five cycles was 154.39 mL/g under identical conditions, compared to only 137.39 mL/g for unmodified CaO. The adsorption energy of the catalysts before and after modification increased in the order of CaO < CaTiO < CaAlO, with values of −0.99, −3.67, and −5.92 eV, respectively. Doping CaO with Al and Ti and the adsorption of CO 2 molecules enhanced the activity of O surf atoms on the catalyst surface, leading to an increase in the surface PV of C atoms. This enhancement was evident as the PDOS of C atoms on the CO 2 surface shifted to the left, which improved its adsorption capacity. The number of Ca–O bond populations and bonding positions in the material increased, and the number of Al–Ca and Ti–O bond populations reached 0.66, making it more conducive for recycling during intensified hydrogen production.