Molecular dynamic(MD) was used to study the crosslinking process of ethyl cellulose (EC).And the diffusion be-haviors of model gasoline components (thiophene, n-heptane, cyclohexane, cyclohexene, and toluene) in EC with different crosslinking degrees were investigated. The trajectory of small molecule diffusing in polymer was drawn and the diffusion behav-ior was analyzed accordingly. Then,the diffusion coefficients of gasoline components in EC systems,as well as thethiophene dif-fusion selectivity were calculated. The micro mechanism of EC crosslinking on molecule diffusion was investigated by analyzing fractional free volume(FFV) of polymer,X-ray diffraction pattern and the mobility of polymer chains. The results show that with the increase of crosslinking degree,the energy of hydrogen bonds decliness,and the interlayer distance improves.Howev-er,the free volume and self-diffusion coefficient of polymer chains firstly increase and then decrease,which leads to the same change trend of the diffusion coefficients gasoline components and thiophene diffusion selectivity. And it was concluded that there is an optimum degree of crosslinking for EC membrane to achieve the best desulfuration performance.%采用分子动力学(MD)模拟乙基纤维素(EC)的交联过程,考察典型汽油组分(噻吩、正庚烷、环己烷、环己烯和甲苯)在不同交联度EC中的扩散行为,绘制小分子在聚合物中扩散轨迹并分析其扩散方式,计算汽油组分在EC中的扩散速率与噻吩扩散选择性.通过分析聚合物自由体积、XRD谱图、分子链运动性,研究EC交联对分子扩散影响的作用机制.结果表明;随着交联度增加,EC内氢键作用能下降,分子间距增加,自由体积和分子链运动性呈现先增加后减小的趋势,进而导致汽油组分在EC的扩散速率和噻吩扩散选择性也呈现相同趋势;渗透汽化汽油脱硫过程中EC膜存在最佳交联度.
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