Biomass CO₂ gasification with CaO looping for syngas production in a fixed-bed reactor

The most important challenge in solid feedstock thermal conversion methods is minimising CO₂ emissions. In this work, the gasification of pine sawdust in a mixture of N₂ and CO₂ was investigated for the reduction of CO₂ by a calcium oxide loop. The experiments were conducted at 600, 700, and 800 °C in a fixed-bed reactor. The biomass was mixed with the calcium oxide at a ratio of 1:1. The chemical composition of the syngas was analysed using gas chromatography. Moreover, the high heating values of the received gas samples were calculated, and thermogravimetric analysis and Fourier-transform infrared spectroscopy analysis were performed to investigate the absorption of CO₂ by CaO. The results of the gasification process showed that the syngas contained CO, CH₄, CO₂, H₂, N₂, and other low hydrocarbons. The most significant results were obtained for a 2:1 ratio of N₂ to CO₂ at 700 °C, and a CO₂ reduction of 25% was observed. Moreover, the catalytic properties of CaO increased the concentration of H₂ in the produced syngas by up to 10%. A temperature of 800 °C was too high for the carbonation reaction of CaO. This study presents a possible solution for achieving negative carbon emissions.