Computer Simulation of Methanol Swelling of Coal Molecules

Effect of Different Coal Fractions

Abstract

A molecular mechanics / molecular dynamics computational method was used to simulate methanol swelling of solvent-soluble fractions obtained from extraction of Upper Freeport bituminous coal. The pyridine-soluble (PS) and pyridine-insoluble (PI) fractions were used as coal sample. The effect of PS on methanol swelling was examined and compared with previous results for PI. As methanol molecules were added to a model compound of PS fraction under periodic boundary conditions, the potential energy of the PS-methanol system decreased and the volume of the cell increased up to the limiting number of methanol, after which the rate of increase was larger with increasing the total energy. The swelling ratio estimated from the ratio of the weight increase with the number of methanol molecules introduced was in agreement with the ratio determined experimentally from sorption data. The lighter fraction PS showed smaller changes in the total energy and a larger ratio of volume increase with introducing methanol molecule into the system.