Molecules Simulation Study Of Coal And Different Gases Adsorption Processes

This thesis outlines the current status of molecular simulation research at home and abroad,the current status of molecular structure research on coals with different degrees of metamorphism,and the current status of coal and gas molecules adsorption research based on molecular simulation.By using both computational simulation and theoretical research,the conformation and energy of methane,carbon dioxide and nitrogen molecules adsorbed on the surface of lignite,sub-bituminous coal,bituminous coal and anthracite coal were analyzed by using two different software,Gaussian and Materials Studio,respectively,and the adsorption energy and location of methane were calculated and analyzed from three aspects,namely,adsorption of single methane,adsorption of multiple methane and adsorption of multi-component gas mixture.The calculation and analysis were carried out from the perspectives of adsorption energy and adsorption location,and the adsorption configurations of methane,carbon dioxide and nitrogen molecules adsorbed by coal molecules with different degrees of metamorphism and the ranking of adsorption ease were obtained respectively,and the data generated by the two software were also analyzed separately,namely the similarities and differences between them were obtained.The following main conclusions were drawn:(1)When different coal molecules adsorbed individual methane molecules separately,the adsorption energy of coal surface molecules in the process of methane adsorption was calculated to be ranked from largest to smallest as sub-bituminous coal,lignite,bituminous coal,and anthracite,and the adsorption atomic distance had an opposite relationship with the ranking of the adsorption energy;and the optimal adsorption positions were all close to the oxygen atoms on the hydroxyl groups on the side chains.(2)The relationship between the adsorption energy and other related parameters and the number of adsorptions was investigated when anthracite coal was adsorbed with multiple methane.(3)When the anthracite coal adsorbs methane,carbon dioxide and nitrogen molecules simultaneously,the calculated adsorption energy is smaller than the total value obtained by adding the adsorption energies of the anthracite coal when adsorbing methane,carbon dioxide and nitrogen separately.(4)The adsorption of a finite number of gas molecules on coal molecules was studied,the adsorption capacity of methane,carbon dioxide,and nitrogen when interacting with the same coal molecule is carbon dioxide > nitrogen > methane.