Clarification of gasification behavior of solid fuel char prepared under CO2 atmosphere

This study aimed to examine the effect of CO2 atmosphere during pyrolysis of solid fuel on the gasification of its char by using thermobalance. As the sample, alkali-rich lignin was prepared. The lignin sample was pyrolyzed at heating rate of 1K/s to 700C under CO2 and Ar, and these chars (ligninchar-CO2, ligninchar-Ar) are gasified in air at various temperatures, from 700C to 1140C. The difference of gasification behavior between ligninchar-CO2 and ligninchar-Ar was varied according to rate limiting process, in fact, kinetic controlled region (Zone I) or internal and external diffusion controlled region (Zone II&III). At Zone I, carbonate formation by reacting alkali metal with CO2 has a possibility to inhibit gasification. At Zone II&III, on other hand, the gasification rate of lignin char prepared in CO2 was higher than that of lignin char made in Ar. This is considered to be caused by its porous morphology due to CO2 in char preparation.