The Boltzmann-Monte-Carlo-Percolation (BMCP) model on pyrolysis of coal: The quantitative correction on CP/MAS 13C solid-state NMR spectra and insight on structural evolution during coalification

Abstract

Because of the Nuclear Overhauser Effect (NOE), the quantitative bonds’ population can hardly be obtained directly from Cross-polarization Magic Angle Spinning (CP/MAS) 13C solid-state Nuclear Magnetic Resonance (NMR) spectra. Thus, correction must be carried out to obtain the bonds’ population with high precision. In this work, the correction factor was derived from Solomon equation, and the previously developed Boltzmann-Monte-Carlo-Percolation (BMCP) model was employed reversely to the calculate correction factor from the tar yields of coal pyrolysis. The results showed that correction on the bonds’ population from tar yields improved the prediction results both on the bonds’ population and product distribution; the correction factor showed an abrupt trend corresponding to coalification jumps. Furthermore, an empirical equation for calculating the correction factor was obtained. The success of the correction indicates that the pyrolysis behaviors of coals under moderate conditions are governed by the bonds’ population, and BMCP model is a proper way to describe the structure–activity relationship quantitatively.