The Distribution and Change of Oxygen-Containing Functional Groups in Coal

Oxygen-containing functional groups are the most important active groups of coal and critical for heating. This paper collected five different coal samples and explored the distribution of main oxygen-containing functional groups (hydroxyl, carboxyl, methoxyl, carbonyl and inactive oxygen) and their changes after oxidation with chemical titration and Fourier Transform infrared (FT-IR) spectroscopy. The results show that there are mainly hydroxyl and no carboxyl in anthracites; in meagre coal, the hydroxyl- and carboxyl-based oxygen-containing group is more uniform, and coking coal has comparable hydroxyl, carboxyl, methoxyl and inactive oxygen, except carbonyl. After oxidization, the methoxyl and inactive oxygen decreases, as well as the total oxygen-containing functional groups. The ratios of hydroxyl, methoxyl, carbonyl and inactive oxygen decrease and the carboxyl rises in anthracites; the proportions of carboxyl, methoxyl and inactive oxygen decline and carbonyl goes up in coking and meagre coal from Tangshan Mine and Fan’gezhuang Mine. However, for the coking coal from Pingdingshan Mine, the ratios of hydroxyl and carbonyl rise and methoxyl, carbonyl, inactive oxygen decrease. The research about oxygen-containing functional groups could be a reference to further understand the mechanism of coal spontaneous combustion.