Catalytic Gasification of Biomass in a CREC Fluidized Riser Simulator

Abstract

Gasification of biomass is an environmentally important technology that may contribute to fulfill requirements set by the Kyoto protocol. Biomass can be converted into a vast array of chemical products and fuel, and can be utilized to produce power/electricity. However, a major limitation of biomass gasification is the resultant tars and particulate matter that potentially destroy downstream process equipment, harm the environment, and hinder economic efficiency. This study considers the catalytic steam gasification of waste-wood, with the catalyst being fluidizable nickel/a-alumina. Experiments are conducted in the CREC Riser Simulator Reactor, at temperatures between 800°C - 850°C, near atmospheric pressures, and reaction times over 10 seconds. Experimental results suggest that catalytic steam gasification of biomass is a versatile process; with a considerable amount of H2 being produced at steam/biomass feed ratios above 0.3kg/kg daf. It is also found that the catalyst effectively converts tars to permanent gases at temperatures ranging from 800°C - 850°C and for steam/biomass feed ratio ranging from 0.17 – 0.58kg/kg daf, with the carbon conversion being above 90% in all cases. An equilibrium model from the literature is developed and modified, and then considered to analyze the experimental data. At 800°C and steam/biomass ratios from 0.17 – 0.42kg/kg daf, the H2/CO product ratio is estimated accurately by the equilibrium model. However, product lump compositions are estimated with less accuracy, which provides support to the need of a non-equilibrium model to fully explain the inter-conversion of gaseous species following biomass catalytic gasification.