Experimental study on supercritical carbon dioxide gasification of biomass

With the excessive use of fossil energy and concern for environmental protection, biomass gasification as an effective means of biomass energy utilization has received widespread attention worldwide. Supercritical carbon dioxide (SCCO₂) (T ≥ 31.26 °C, P ≥ 72.9 atm) has the advantages of near liquid density and high solubility, and the supercritical carbon dioxide gasification of biomass will be a promising technology. However, there has been no research on the technology at present. In this work, experimental study on supercritical carbon dioxide gasification of biomass were carried out in a batch reactor. The influences of temperature, residence time, the amount of carbon dioxide and catalyst on gas yield and fraction were investigated. Experimental results showed that the gas yield and carbon gasification efficiency (CE) of biomass gasification increased with increasing temperature, reaction time or the amount of carbon dioxide. As the gasification temperature increased from 700 °C to 900 °C, the gas yield increased from 23.53 to 50.24 mol/kg biomass and CE increased from 47.26% to 94.53% in CO₂ atmosphere at 30 min. The gasification efficiency of biomass was greatly improved with catalyst, and the effect of impregnated catalyst was better than that of mechanical mixing. The gas yield increased from 23.72 to 50.24 mol/kg biomass with the increasing of the equivalent ratio from 0 to 1 at 900 °C and 30 min. Finally, a detailed supercritical carbon dioxide gasification mechanism of biomass was proposed.