新疆尼勒克长焰煤大分子模型构建及CH4吸附特征分析OA

Accurate characterization of coal macromolecular structures is crucial for revealing the mechanism of methane(CH4)adsorption in coal rock.In this study,the macromolecular structure of Long-Flame coal from the Nileke region in Xinjiang was characterised using industrial analysis,elemental analysis,Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and solid-state nuclear magnetic reso-nance(13C-NMR).Coal macromolecular models were constructed using ACD Predictor and Materials Studio software.Molecular dynamics(MD)and grand canonical Monte Carlo(GCMC)numerical simulation methods,and isothermal adsorption experiment physical simulation methods were used to study the CH4 adsorption char-acteristics of coal rock under different temperature and pressure conditions.The results show that(1)The aro-matic structure of Nileke long-flame coal consists of benzene rings and naphthalene,with a bridge carbon to peripheral carbon ratio of 0.21.Methylene groups dominate the aliphatic structure(54.66％),followed by methyl(28.12％)and methine groups(17.22％).Oxygen-containing functional groups include 17 hydroxyl groups,1 ether bond,3 carbonyl groups,and 4 carboxyl groups.Nitrogen is present as pyridine and pyrrole.(2)The molecular formula of Nileke long-flamed coal is C171H178O29N2,with a molecular weight of 2,725,a porosity of 15.21％,and a critical peak value of 1.8 Å in the pore size distribution.(3)The trends in CH4adsorption isotherms obtained from physical simulation and numerical simulation are basically consistent.In the isothermal adsorption process,the adsorption amount increases rapidly below 10 MPa,increases more slowly between 10 MPa and 25 MPa,and stabilizes or slightly decreases above 25 MPa.(4)CH4 molecules preferentially adsorb on larger micropores and finally occupy smaller micropores.During the isobaric process,the adsorption amount shows a linear decrease with increasing temperature.This study provides a validated coal macromolecular model and molecular-scale theoretical insights supporting the efficient development of coalbed methane(CBM)in the Nileke region.