Coal gasification fine slags: Investigation of the potential as both microwave adsorbers and catalysts in microwave-induced biomass pyrolysis applications

Abstract

The coal gasification fine slags (CGFS) are rich in porous carbon and various metal elements (Al, Fe, Ca, Na, K, Mg). In this work, three types of CGFS-based catalysts (CGFS@GSP, CGFS@OMB, and CGFS@TEX) were prepared and used in microwave-induced biomass pyrolysis to investigate the possibility of CGFSs as both microwave absorbing materials and catalysts for synergistic renewable phenols and fuel gas production. The CGFS-based catalysts displayed rough and porous structures, containing a variety of active metals and compounds. Remarkable microwave absorbing ability with higher heating rates than SiC was achieved by the CGFS-based catalysts during biomass pyrolysis. The catalysts showed high activity for biomass pyrolysis under microwave heating conditions, resulted in the increase of gas yield and the decrease of water and bio-oil yields. The bio-oil chemical composition was significantly simplified and was dominated by C3–C10 compounds. Phenols are the dominant component in the produced bio-oil, and the content reached 69.6% and 71.3% using CGFS@OMB and CGFS@TEX as the catalysts. Meanwhile, the gas yield was significant improved by the catalysts at a higher temperature of 650 °C, and the value reached 64.4% using CGFS@OMB as the catalyst with a remarkable hydrogen concentration of 44.9%.