Acidic oxygen-containing groups and their inhibition methane adsorption of Yima lignite maceral components

To explore effects of acidic oxygen-containing groups on adsorption behavior of low-rank-coal methane, on the basis of collecting and separating maceral components of Yima lignite, acidic oxygen-containing groups of lignite maceral components were characterized by means of FT-IR and Boehm titration. The basic structural unit nuclei was calculated via coal chemical statistical structure analysis, and methane adsorption of the maceral component enrichments and the model compounds with different acidic oxygen-containing groups were determined through weight method. The results show that: the highest total amount of acidic oxygen-containing groups and the highest content of carboxyl, phenolic hydroxyl and lactone in the maceral-component enrichments are liptinite, humic and interia. By different acidic oxygen-containing groups, a priority order for methane adsorption inhibition on lignite naphthalene is carboxyl, phenolic hydroxy, lactone; the relative adsorption inhibition of the carboxyl is about 7 times and 3.3 times that of the lactone and the hydroxyl. Without considering the water condition, carboxyl content increasing is the main factor resulting in the amount decreasing of methane adsorption capacity of each maceral component. The study reveals that the surface property and content of maceral components are important factors affecting the gas content of lignite, and the higher content of carboxylic acid in Yima lignite inertial group is significant for methane adsorption inhibition. © 2018, Editorial Board of Journal of CUMT. All right reserved.