In this paper we have simulated the competitive adsorption of CO2, CH4, and N2 gases in deep coal seams by building a graphite supercell structure and discussed the impact of pressure, pore size, and multicomponent composition on CH4 desorption. The results show that the adsorption capacity of a single component gas changes is in the order of CO2 > CH4> N2. For the CH4/CO2 competitive adsorption, absorbed CO2 can reach saturation at low pressure conditions. CO2 has an adsorptive advantage compared with CH4. It is shown that CO2 can promote the CH4 desorption by the displacement mechanism. For CH4/N2competitive adsorption, the adsorption capacity of N2 is weaker than that of CH4, demonstrating that improvement in coalbed methane (CBM) production by N2 injection is achieved by reducing the partial pressure and creating flow channels. The presence of H2O has a greater impact on the gas with a stronger adsorption capacity in the binary component system. For the CH/CO2/N2 competitive adsorption, the CO2 adsorption is dominant in 1 nm slit pores, while CH4 adsorption is dominant in 2 nm slit pores. This indicates that when the pore diameter increases, the CO2/N2 injection does not promote CH4 desorption. H2O also has a significant impact on the competitive adsorption in the ternary component system. The strong interaction between H2O and CO2 weakens the CO2 adsorption capacity.

中文翻译：

---

深煤层 CO2、CH4 和 N2 竞争吸附的分子模拟

在本文中，我们通过构建石墨超胞结构模拟了深部煤层中 CO2、CH4 和 N2 气体的竞争吸附，并讨论了压力、孔径和多组分成分对 CH4 解吸的影响。结果表明，单组分气体的吸附量变化顺序为CO2>CH4>N2。对于 CH4/CO2 竞争吸附，吸附的 CO2 可以在低压条件下达到饱和。与 CH4 相比，CO2 具有吸附优势。结果表明，CO2 可以通过置换机制促进 CH4 解吸。对于 CH4/N2 竞争吸附，N2 的吸附能力比 CH4 弱，这表明通过降低分压和创建流动通道实现了通过 N2 注入煤层气（CBM）生产的改进。H2O的存在对二元体系中吸附能力较强的气体影响较大。对于 CH/CO2/N2 竞争吸附，CO2 吸附在 1 nm 狭缝孔中占优势，而 CH4 吸附在 2 nm 狭缝孔中占优势。这表明当孔径增大时，CO2/N2 注入不会促进 CH4 解吸。H2O 对三元组分系统中的竞争吸附也有显着影响。H2O 和 CO2 之间的强相互作用削弱了 CO2 的吸附能力。CO2/N2 注入不会促进 CH4 解吸。H2O 对三元组分系统中的竞争吸附也有显着影响。H2O 和 CO2 之间的强相互作用削弱了 CO2 的吸附能力。CO2/N2 注入不会促进 CH4 解吸。H2O 对三元组分系统中的竞争吸附也有显着影响。H2O 和 CO2 之间的强相互作用削弱了 CO2 的吸附能力。