Experimental Study on Gas Adsorption and Desorption Laws of Air-dried Coal Samples with Different Soaking Time

In order to study the gas adsorption and desorption laws of soaked and air-dried coal samples, the air-dried coal samples soaked with 3 day, 15 day, 30 day and raw coal without soaking were tested in the dynamic gas adsorption experiment under a constant temperature and pressure, we found that the experimental curves of cumulative amount of gas adsorption and desorption changed with time under different pressure. The experiment of specific surface area and pore size analysis on coal samples were conducted to obtain specific surface area, pore volume and pore size. The results show that the trend of the cumulative adsorption amount of air-dried coal samples with different soaking time changes with the gas pressure, which is consistent with the raw coal samples without soaking. The reciprocal of the desorption amount of soaked and air-dried coal samples is linearly related to the time function within the initial 20 min of desorption. With the increase of soaking time of air-dried coal samples, the saturated adsorption amount, specific surface area, total pore volume and micropore volume of air-dried coal samples decrease and then increase, but the average pore size increases first and then decreases.