Influence of active alkali and alkaline earth metals on physicochemical structures of co-pyrolysis-gasification coupling char

The influences of active alkali and alkaline earth metals (Ac-AAEMs) on the physicochemical properties of chars during co-pyrolysis-gasification coupling were studied in this paper. The mixed samples were obtained according to four mixing ways: original coal and original corn stovers (OSM+OCS), pickling coal and original corn stovers (PSM+OCS), original coal and pickling corn stovers (OSM+PCS), and pickling coal and pickling corn stovers (PSM+PCS). The influences of Ac-AAEMs in OSM (Ac-AAEMs-OSM), Ac-AAEMs in OCS (Ac-AAEMs-OCS), and Ac-AAEMs in OSM+OCS (Ac-AAEMs-blends) on the pore structures of gasification chars were characterized by I_OSM, I_OCS, and I_OSM+OCS, respectively. The results showed that Ac-AAEMs-OCS and Ac-AAEMs-blends, especially Ac-AAEMs-OCS, significantly promoted the development of mesopores. Furthermore, Ac-AAEMs-OCS and Ac-AAEMs-blends have good catalytic effects on the specific surface area of chars, especially at 20 minutes of gasification. Compared with PSM+PCS char, the specific surface areas of PSM+OCS char, OSM+OCS char, and OSM+PCS char obtained at 20 minutes of gasification increased by 203%, 157%, and 7%, respectively. Besides, the Ac-AAEMs are conducive to destroying the carbon structure with a high graphitization degree and promoting the formation of disordered amorphous carbon. The magnitude of their catalytic ability is Ac-AAEMs-blends >Ac-AAEMs-OCS>Ac-AAEMs-OSM.