基于DFT方法的注热蒸汽开采CH_4吸附机理  

Adsorption mechanism of CH_4 in heat steam injection based on DFT method

作　　者：柴琳[1] 吴世跃[1] 魏杰[1] 牛煜[1] CHAI Lin;WU Shiyue;WEI Jie;NIU Yu(School of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,Chin)

机构地区：[1]太原理工大学矿业工程学院,山西太原030024

出　　处：《煤田地质与勘探》2018年第3期72-78,共7页Coal Geology & Exploration

摘　　要：为探究不同煤阶煤吸附CH_4和H_2O吸附机理,采用量子化学方法中的密度泛函理论(DFT),在B3LYP/6-31G基组上计算了不同煤阶煤的大分子稳定构型及煤分别吸附CH_4、H_2O及CH_4与H_2O共存条件下的吸附能和电荷转移情况。研究结果表明:煤吸附CH_4为物理吸附,随着煤阶升高,煤吸附CH_4能力增强;吸附H_2O时以氢键形式作用,其中煤中含氧官能团为氢键供体,H_2O中-OH为氢键受体,随着煤阶升高,吸附H_2O能力减弱;当H_2O与CH_4共存时,H_2O抢占CH_4吸附位,导致煤优先吸附H_2O,使吸附态CH_4减少,游离态CH_4增多。从分子水平完善了煤吸附甲烷和H_2O的吸附机理,为注热蒸汽开发煤层气奠定了吸附理论基础。In order to study the adsorption mechanism of CH4 and H2O adsorbed on different ranks of coal, the macroscopic macromolecule stability configuration of different coal rank was calculated on the B3 LYP/6-31 G basis group by Density Functional Theory（DFT） in quantum chemistry method. Adsorption energy and charge transfer were calculated when CH4, H2O and CH4 and H2O coexist. The results show that coal adsorption of CH4 is physical adsorption, and the adsorption capacity of CH4 is enhanced with the increase of coal rank. The adsorption of H2O takes the form of hydrogen bond, in which the oxygen-containing functional group is hydrogen bond donor, H2O occupies adsorption sites of CH4 when H2O and CH4 coexist, leading to the adsorption of H2O, the adsorption of CH4 and the increase of free CH4. In this paper, the adsorption mechanism of methane and H2O adsorbed by coal was improved from the molecular level, which laid the theoretical foundation for exploiting coalbed methane by heat injection.

关 键 词：煤化学 吸附 竞争吸附 DFT 注热蒸汽 

分 类 号：P618.11[天文地球—矿床学]