Effect of different moisture content and salinity conditions on CH4 adsorption by coal

Abstract

Coal reservoirs are often connected to hydrogeological systems through faults, allowing groundwater with mineralization to intrude into coal seams. In order to improve gas extraction, it is necessary to explore the effect of coal with different moisture content and salinity conditions on CH4 adsorption. By means of various experimental tests, such as XPS, FTIR, we constructed macromolecular structure models of Dongqu 8# coal with different moisture content and salinity conditions, conducted isothermal adsorption simulation experiments, and analyzed in detail the effects of coal models with different moisture content and salinity conditions on the adsorption capacity of CH4. The results showed that the adsorption capacity of CH4 decreased with the increase of moisture content and salinity in coal; the effect of moisture content on CH4 adsorption was greater than that of salinity on CH4 adsorption; the ability of sodium salt to affect the adsorption of CH4 by coal was ranked from largest to smallest as follows: Na2CO3 > NaHCO3> NaCl; electrostatic potential distribution: | Na2CO3 electrostatic potential| > | NaHCO3 of electrostatic potential| > | NaCl of the electrostatic potential|, it can be seen that the electrostatic force affects the strength of adsorption, the greater the value of the electrostatic potential of the ions in the salt, the stronger ability the coal to adsorb CH4.

Keywords

• gas extraction; ch4
• adsorption action
• molecular simulation
• moisture content
• salinity