Reactive molecular dynamics simulation of oil shale combustion using the ReaxFF reactive force field

Abstract

ABSTRACT Oil shale is a kind of complex carbonaceous material which is an important energy source for electricity production. Reactive molecular dynamics (RMD) simulation is a useful tool to examine the chemical reactions occurring in complex processes, providing a realistic structural representation and an applicable reactive force field (ReaxFF). The molecular dynamics (MD) simulations and Reaxff were employed to investigate the chemical mechanisms and products distribution in the process of oil shale combustion. The combustion process was explored by dividing it into three stages: the process of kerogen oxidation was primarily initialized by the cleavages of weak bonds in stage I; in stage II, kerogen structure was devolatilized to form char particles, then char and most of shale oil combusted; the small molecules (gases and a small of shale oil) generated water and carbon dioxide by O2 molecules, O and OH radicals attacking in stage III. The purpose of the present study was deeply understanding the combustion mechanism and conversion reactions associated with sulfur and nitrogen species of oil shale kerogen during this period by investigating the bond breaking, characteristic products distribution, and typical reaction pathways.