Biomass gasification in supercritical water: II. Effect of catalyst

In this study, the effect of the type of catalyst on hydrothermal gasification of three specifically chosen samples of natural biomass was investigated. Biomass feedstocks, including lignocellulosic materials (cotton stalk and corncob) and the tannery waste, were gasified in supercritical water by the addition of catalyst. The catalysts used were K₂CO₃, Trona (NaHCO₃·Na₂CO₃·2H₂O), red mud (Fe-oxide containing residue from Al-production) and Raney-Ni. The gasification experiments were performed in a batch autoclave at 500 °C. The amounts and compositions of the gases and the amounts of water soluble compounds from gasification were determined. The effect of catalysts on gasification varied with the type of biomass. The catalysts significantly increased the hydrogen yield by supporting the water–gas shift reaction and the methane reformation.