Effects of volatiles and active AAEMs interaction with char on char characteristics during co-pyrolysis

The interactions between volatile substances (volatiles and volatile alkali and alkaline earth metals) released from pyrolysis and char have a crucial influence on the co-gasification process. The influence mechanism of volatiles-char interaction and volatile substances-char interaction in the co-pyrolysis of coal (RSM) and corn stover (RCS) was studied. The findings indicated that volatiles-char interaction suppressed the progression of specific surface area (SSA) and pore structures of char. Volatile active alkali and alkaline earth metals (Ac-AAEMs) of RCS/RSM attenuated the unfavorable effects of volatiles and facilitated the progression of pore structures and SSA of coal/RCS char. Besides, volatiles could react with char through small aromatic ring structures and oxygen-containing groups. The presence of volatile Ac-AAEMs could inhibit the depletion of small aromatic ring structures and oxygen-containing groups caused by volatiles-char interaction. Among them, RCS volatile Ac-AAEMs suppressed the consumption of 11% oxygen-containing groups. RSM volatile Ac-AAEMs inhibited the depletion of 4% oxygen-containing groups. Finally, RCS volatiles-char interaction could inhibit the reactivity of RSM char. The existence of RCS volatile Ac-AAEMs could alleviate the inhibition of volatiles and significantly promote the reactivity of RSM char. Nevertheless, the volatiles and volatile Ac-AAEMs from RSM exhibited minor impacts on RCS char reactivity.