Molecular dynamics simulations and experimental study on deconvolution of volatile–char interaction in coal pyrolysis: Insight into the role of O-containing compound species

Abstract

Information on energy states, evolutionary paths, microstructure, and chemical bonding properties of reactants and products under volatile–char interaction cannot be directly obtained through laboratory experiments. In this study, simulation experiments of volatile–char interaction were performed by ReaxFF-MD method based on interaction experiment of O-containing model compounds. The CO/CO2 generation paths from different O-containing structures during the volatile–char interaction were obtained, and the corresponding thermodynamic parameters were calculated by using DFT. The peculiarities of C–O active site structure greatly reduce the energy barrier for the carbocyclic structural rearrangement of the six-carbon ring, leading to the formation of five-carbon ring cyclopentadienyl group. The electrons provided by the active sites of coal fragments effectively promote the activation of phenol hydroxyl group, resulting in the decrease of ΔELUMO-HOMO and acceleration of interaction process. This study deepens the understanding of chemical site adsorption effect of O-containing compounds in the interaction process from the microscopic level.