The adsorption of dodecyl trimethyl ammonium bromide (DTAB) on coal can affect the wettability of coal and change the water absorption of coal. After DTAB treatment, the change in the CH₄ adsorption capacity of coal is worth further study. To reveal the microscopic mechanism of the influence of DTAB on the CH₄ adsorption capacity of coal, we employed the density functional theory (DFT) with the 6-311 G (d, p) basis set. DFT-based computations interpreted the adsorption process of CH₄ and DTAB on coal molecules and determined the stable structure, adsorption distance, Mulliken overlapping populations, and adsorption energies of the two adsorption configurations. The results showed that the adsorption energies of CH₄ and DTAB on the molecular model of coal were 2.15 and 42.69 kJ/mol and the adsorption stability distances were 0.261 and 0.238 nm, respectively. The DTAB–coal configuration was more stable than the CH₄–coal configuration. When there was competitive adsorption between DTAB and CH₄ on coal, the coal molecules preferentially adsorb the DTAB. Infrared spectroscopy and adsorption experiments were also carried out, and the calculation results of quantum chemistry are consistent with the experimental results.

中文翻译：

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十二烷基三甲基溴化铵对煤中CH4吸附影响的量子化学研究

十二烷基三甲基溴化铵（DTAB）在煤上的吸附会影响煤的润湿性并改变煤的吸水率。经过DTAB处理后，煤中CH ₄吸附能力的变化值得进一步研究。为了揭示DTAB对煤CH ₄吸附容量影响的微观机制，我们采用了密度泛函理论（DFT），其基数为6-311 G（d，p）。基于DFT的计算解释了CH ₄和DTAB在煤分子上的吸附过程，并确定了两种吸附构型的稳定结构，吸附距离，Mulliken重叠种群以及吸附能。结果表明，CH ₄的吸附能为煤分子模型上的DTAB和DTAB分别为2.15和42.69 kJ / mol，吸附稳定距离分别为0.261和0.238 nm。DTAB煤配置比CH ₄煤配置更稳定。当DTAB和CH ₄在煤上竞争性吸附时，煤分子优先吸附DTAB。还进行了红外光谱和吸附实验，量子化学的计算结果与实验结果吻合。