Thermal Behavior and Char Structure Evolution of Bituminous Coal Blends with Edible Fungi Residue during Co-Pyrolysis

Abstract

Co-pyrolysis of coal and lignocellulosic biomass has the potential to mitigate the emission of greenhouse gases from an energy supply. Successful application of this technology requires proper investigation on the influence of coal and lignocellulosic biomass mixing on thermal behavior and product characteristics. Therefore, in this study, thermal behavior of a kind of Chinese bituminous coal blended with edible fungi residue (EFR) was evaluated through nonisothermal thermogravimertic analysis. Raman spectroscopy and scanning electron microscopy with energy dispersive spectroscopy techniques were applied to determine the char structure evolution. The results revealed that the EFR promoted thermal decomposition of the bituminous coal and synergy effect on char yield was observed. The activation energy distribution calculated via an isoconversional method showed nonadditivity performance, which may be caused by the catalytic effects of alkali and alkaline earth metals and the char structure evolution. The Raman spectrum results indicated that the Raman intensity of the co-pyrolysis char increased with the EFR ratio, which can be due to the combined effect of the O-containing groups and nonproportional effects of alkali and alkaline earth metallic species. The area ratio of the G (graphite) band to all the bands (AG/Aall) and that of the valley between D (disordered) and G bands to the D band (AGR/AD and A(GR+VL+VR)/AD) had been found useful in evaluating the evolution of the char structure. An increase in AG/Aall seemed to suggest the increasing aromatization of the chars. The increase in AGR/AD and A(GR+VL+VR)/AD implied the generation of more smaller (3–5 rings) aromatic ring structures and the elimination of lager (no less than 6 rings) aromatic ring systems in the char samples as the EFR ratio increasing.