Alkali catalysis in biomass gasification

The mechanism of biomass gasification in the presence of alkali catalysts was investigated using two reactor systems. Tests at both high pressure and low temperature as well as low pressure and high temperature confirmed that an increase in gas production from whole biomass and biomass components is achieved in the presence of alkali. Supporting investigations elucidated the chemical pathways affected by the alkali and the alkali's effect on several physical parameters. The char-steam reaction was judged not to be diffusion limited in our high-temperature system. In addition, alkali-induced swelling of biomass was determined to be unrelated to the catalytic effect.     

Catalyzed steam gasification of biomass

Steam gasification of wood in the presence of catalysis was investigated. Two methods for wood/catalyst contacting were used: dry mixing of the wood and solid catalyst and impregnation of the wood with catalyst. Impregnation gave greater yields and rates than dry mixing and was used throughout the remainder of the investigation.Catalysts used included potassium carbonate, sodium carbonate, trona, and borax, in order of their effectiveness at all temperatures.The gasification process with and without catalyst occurred in two stages: (1) a rapid pyrolysis immediately after heatup and (2) reaction of steam with the char residue. The steam/char reaction obeyed pseudo-first-order kinetics.