Mechanism of Woody Biomass Pyrolysis and Gasification in a Fluidized Bed of Porous Alumina Particles

Abstract

To understand the mechanism of steam gasification of woody biomass, pyrolysis and gasification were carried out at 773 and 973 K on porous γ-alumina in a two-stage fluidized bed reactor. Significant amounts of volatiles, including gas and tarry materials, were formed upon devolatilization, but the tar was mostly captured by the alumina. The tar captured on the alumina was subsequently reformed with the steam to H2 and CO. However, little of the char was gasified under the present conditions. CO and water molecules penetrated into the large pores of the char, allowing the water−gas shift reaction to occur on the active sites on the surface of the char. Although the char itself was not gasified at these relatively low temperatures, it played an important role in the water−gas shift reaction.