中文摘要：

Al,Si,P和S掺杂石墨烯（X-Graphene,X-Gr,X=Al,Si,P和S）可用来代表具有结构异性的煤结构模型.通过自旋极化的密度泛函理论（DFT）方法,研究了煤层气（Coalbed methane,CBM,主要成分为CH4,CO2和H2O）在煤结构模型X-Gr上的吸附,并讨论了相应的吸附能、吸附平衡距离、Mulliken电荷转移、电荷密度差分图和态密度.结果表明,含Al和Si的煤结构模型对CBM的吸附较强,而CBM在P和S煤结构模型的吸附为弱的物理吸附.CBM在X-Gr煤结构模型上的吸附作用随着掺杂元素非金属性的增强而减弱,即Al-Gr〉Si-Gr〉P-Gr〉S-Gr.煤层气中CO2和H2O吸附在煤炭表面的能力强于CH4,可以通过注入CO2和H2O到煤层中促进CH4的开采.此外,含Al和Si煤结构与煤层气之间较强的相互作用表明其可以作为CH4,CO2和H2O的气体传感器.

英文摘要：

Al-,Si-,P- and S-doped graphenes（ X-Gr,X = Al,Si,P and S） were used to represent the surface models of coal with the structural heterogeneity. Based on the spin-polarized density-functional theory,coalbed methane（ CBM,the main components are CH4,CO2 and H2O） adsorption on X-Gr was investigated and the corresponding adsorption energy,adsorption equilibrium distance,Mulliken charge,charge density differences and density of states were well discussed. The result show that Al- and Si-Gr are sensitive to CBM,whereas CBM adsorptions on P- and S-Gr are found to be physical adsorption. In brief,the interactions between CBM and X-Gr are slightly depend on the orientations of CBM gas molecules and the metallicity of the dopants in Gr. The higher adsorption energy,the higher metallicity of the dopants becomes,namely Al-Gr 〉Si-Gr 〉 P-Gr 〉 S-Gr. Through systematical and theoretical analysis,we found that CO2 and H2O were easy to adsorb on surface models of coal than CH4. Hence,injection of CO2 or H2O in coal seams could enhance CH4 recovery. In addition,we suggest that Al- and Si-Gr could be a good gas sensors for CBM because of the higher interactions between Al-/ Si-Gr and CBM.