Insights into the structures of coals and chars from a bond and radical perspective using Raman spectroscopy

Deconvoluting method is crucial for Raman spectra of coals or chars because the obtained parameters are used to correlate with various reaction behaviors. In this work, Raman spectra of 15 coals and 45 chars prepared under 300, 600, and 900 degrees C, were deconvoluted into nine sub-curves. Using cross-polar/magic angle spinning C-13 solid-state NMR spectra (CP/MAS C-13 NMR) and Electron Spin Resonance (ESR) spectra, the validities of traditional functions A(D)/A(G) and A((Gr+v1+vr))/A(D) were evaluated, and new function A(D)/A((s+A1+A2)) correlated with defects was constructed. The physical meaning of some sub-curves was determined by analyzing the comparison between the Raman and other spectra. The deconvoluting method can be adopted to other hydrocarbons and new functions reflect other structural characteristics can be constructed using similar method.

Automated summary

Deconvoluting method is crucial for analyzing Raman spectra of coals and chars, and in this study, a new function correlated with defects was established using this method. The technique can be applied to other hydrocarbons for constructing functions reflecting different structural characteristics.