Thermal Behavior and Char Structure Evolution of Bituminous
Coal Blends with Edible Fungi Residue during Co-Pyrolysis
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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 (<i>A</i><sub>G</sub>/<i>A</i><sub>all</sub>) and that of the valley between D (disordered) and G bands
to the D band (<i>A</i><sub>GR</sub>/<i>A</i><sub>D</sub> and <i>A</i><sub>(GR+VL+VR)</sub>/<i>A</i><sub>D</sub>) had been found useful in evaluating the evolution of
the char structure. An increase in <i>A</i><sub>G</sub>/<i>A</i><sub>all</sub> seemed to suggest the increasing aromatization
of the chars. The increase in <i>A</i><sub>GR</sub><i>/A</i><sub>D</sub> and <i>A</i><sub>(GR+VL+VR)</sub><i>/A</i><sub>D</sub> 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