Pore structure development of oxidized coal and its effect on oxygen adsorption capacity

Abstract

ABSTRACT To explore the surface properties of oxidized coal and reduce its risks of spontaneous combustion, the pore structure development of oxidized coal and its effect on oxygen adsorption capacity were studied by using liquid nitrogen adsorption and oxygen adsorption analysis techniques. The results show that the pore structure development of oxidized coal increases the pore volume and specific surface area. Micropore surface area is the main component of the specific surface area of coal. The mesopores of oxidized coal break into micropores and small pores. Among them, micropores are the most developed to generate more active adsorption sites, and the order of micropore growth is Coal 1 lignite>Coal 3 fat coal>Coal 2 gas coal. A deeper oxidation degree of coal corresponds to a greater number of active adsorption sites generated on the oxidized coal surface, which promotes the adsorption of oxygen on the surface. The order of oxygen adsorption capacity growth is Coal 1 lignite>Coal 3 fat coal>Coal 2 gas coal. The specific surface area is positively correlated with the maximum oxygen adsorption capacity. The order of sensitivity of the maximum oxygen adsorption capacity to the growth of specific surface area is Coal 1 lignite>Coal 2 gas coal>Coal 3 fat coal. The pore structure development could promote the generation of active adsorption sites and enhance the oxygen adsorption capacity of the oxidized coal surface.