Simulation study for identifying the mechanism of direct liquefaction of coal-related model compounds with methanol as solvent

The primary objective of the present study is to investigate the mechanism of direct liquefaction of coal-related model compounds and to explore the influence of methanol as a solvent by using ReaxFF molecular dynamics simulation (MDS) software. A total of nine different coal-related model compounds viz. phenanthrene (PH), diphenylmethane (DM), naphthol (NP), phenol (PL), diphenyl ether (DP), dibenzyl ether (DB), dibenzothiophene (DBT), dibenzofuran (DF), and quinoline (QN) were considered to identify the complex reaction mechanisms, formation of intermediates, and the effects of methanol during the liquefaction process. For the simulation study, 8 molecules of a particular model compound were considered along with 80 methanol molecules in a \(20\times 20\times 20\) $20\times 20\times 20$ Å simulation box. The simulation studies were performed at 20 and 100 K/ps heating rates for the final temperature of 3000 K with a total simulation time of 150 ps duration. Methanol facilitated the breaking of C–O, C–S, C–N, and C–C bonds. Diphenylmethane led to a yield of 65.5 wt% of light tar (LT) at 20 K/ps, and the yield of light tar and heavy tar (HT) + char was maximum for DM at 65.5% and for DP at 43.10% for 20 K/ps. For 100 K/ps, the yield of LT and HT + char was maximum for DP at about 24.1% and for DM at about 69.39%.