Study on CO₂ gasification reactivity of rice straw chars

The CO₂ gasification reactivity and structure of rice straw chars  and the effects of pyrolysis temperature and heating rate were studied. Char samples were prepared by pyrolysis at 550℃~950℃ with heating rates from 0.1K/s to 500K/s in three different pyrolyzing reactors. The CO₂ gasification reactivity of char was determined by means of isothermal thermo-gravimetric analysis on a STA409 TGA. Results show that the gasification reactivity of char increases with the decreasing of pyrolysis temperature and with the increasing of heating rate. It is found that the gasification reactivity of char increases when the gasification temperature rises from 850℃ to 950℃. Scanning electron microscopy (SEM) analysis was employed to determine the impact of pyrolysis heating rate on the char structure. It is indicated that the char pyrolyzed at 500K/s is of more cavities than the char pyrolyzed at 0.1K/s. Moreover, the kinetic parameters based on the mixed reaction model were obtained.