Structural and gasification kinetic studies on co-pyrolysis chars of coal and biomass

The CO2 gasification behaviors of co-pyrolysis chars of coal and biomass were investigated using isothermal thermogravimetry at 950-1150 degrees C. The TGA results showed that char gasification reactivity with higher biomass composition was better than that with lower biomass composition. The results from BET and XRD indicated that biomass can promote the growth of porous structure and inhibit graphite-like carbon formation during the co-pyrolysis of coal and biomass. An extended random pore model was proposed to define the gasification kinetics of the co-pyrolysis chars. The activation energies (Ea) of chars were observed to be reduced with increasing biomass composition. Meanwhile the synergetic influence of interactions between char/mineral and mineral/mineral on the whole co-gasification process was predicted. The relationship between the gasification reactivity and char characteristics was also analyzed. G(X): a function describing the effect of ash and carbon matrix evolution on gasification reaction rate.