Comparison of Thermodynamic and Experimental Yields during Supercritical Water Gasification of Biomass and Pyrolysis Char

Materials with different C/O ratios and volatile matter content (E.grandis and four pyrolysis chars of E.grandis) were used as feedstock during SCWG experiments at 450 °C and 27 MPa. Experimental gas yields and gasification efficiencies were compared to calculated thermodynamic equilibrium results to determine the effect of O/C ratio and volatile matter content on the experimental and thermodynamic equilibrium product yields. Thermodynamic equilibrium calculations show that feed material with low O/C ratios will result in the highest CH4 yields. Experimental results however showed that the volatile matter in the feed material (not considered during equilibrium calculations), affects the extent in which the carbon in the feed material is converted to the gas phase.