Experimental and molecular dynamics simulation of organic structure of bituminous coal in response to acetic acid

Abstract

To investigate the effect of acetic acid on the organic structure of coal, experimental studies and molecular dynamics simulations were used to jointly characterize the response mechanism of the organic structure of coal to acetic acid. The functional groups of coal after the dissolution of different concentrations of acetic acid were tested using Fourier infrared spectroscopy, and the results showed that: the sensitivity of functional groups in coal to different concentrations of acetic acid differs, and acetic acid mainly acts to break the linkage bonds between molecules and hydroxyl groups, producing a large amount of –OH; high concentrations (100% and 75%) of acetic acid react with CH2 alkanes to produce new CH2 alkanes, but low concentrations (50% and 25%) acetic acid does not undergo this reaction. In this paper, we model the solid–liquid system of coal-acetic acid reaction, simulate and characterize the reaction of bituminous coal organic structure to acetic acid, and find that: water molecules can help acetic acid molecules adsorb on the surface of coal molecules, but water molecules will occupy a large amount of space, thus affecting the adsorption of coal molecules. Most of the coal molecules have water molecules and acetic acid molecules adsorbed on the benzene ring and oxygen-containing functional group structures, while the functional groups associated with aliphatic groups in coal molecules are difficult to adsorb due to their hydrophobicity.