Li Wen-Zhuo, Liu Zi-Yang, Che Yu-Liang, Zhang Dan
Department of Chemistry, Zhejiang University, Hangzhou 310027, China.
J Colloid Interface Sci. 2007 Aug 15;312(2):179-85. doi: 10.1016/j.jcis.2007.04.014. Epub 2007 Apr 13.
Grand canonical Monte Carlo and configurational-bias Monte Carlo techniques are carried out to simulate the adsorption of ternary and quaternary mixtures of short linear alkanes, involving methane, ethane, propane, and n-butane, in pillared layered materials at ambient temperature, T=300 K. In the simulation, a pillared layered pore is modeled by a uniform distribution of pillars between two layered walls built by making two separate talc lamellas parallel each other with a given size of interlayer distance. The interaction between fluid molecules and two layered walls is measured by storing potentials calculated in advance at a series of grid points. The interaction between fluid molecules and pillars is also calculated by a site-to-site method. The potential model proposed in this work is proved to be effective because of the simulation result being good agreement with the experimental data for the adsorption of nitrogen at 77 K. Then, the adsorption isotherms of mixtures of short linear alkanes in pillared layered pores with three different porosities psi=0.98, 0.93 and 0.85, and three pore widths H=1.02, 1.70 and 2.38 nm at 300 K are obtained by taking advantage of the model. The simulation results tell us that the longer chain component is preferentially adsorbed at low pressures, and its adsorption increases and then decreases as the pressure increases while the shorter chain component is still adsorbed at high pressures. Moreover, the sorption selectivity of pillared layered materials for the longest chain component in alkane mixtures increases as the mole fraction of methane in the gas phase increases. The selectivity of pillared layered materials for the longest chain component in alkane mixtures also increases as the pore width decreases and the porosity increases.
采用巨正则蒙特卡罗和构型偏倚蒙特卡罗技术，在环境温度T = 300 K下，模拟短链线性烷烃（包括甲烷、乙烷、丙烷和正丁烷）的三元和四元混合物在柱撑层状材料中的吸附情况。在模拟中，柱撑层状孔隙由两个平行的滑石薄片构成的层状壁之间的柱状物均匀分布来建模，层间距离给定。通过存储预先在一系列网格点计算的势能来测量流体分子与两个层状壁之间的相互作用。流体分子与柱状物之间的相互作用也通过逐点法计算。由于模拟结果与77 K下氮气吸附的实验数据吻合良好，证明了本工作中提出的势能模型是有效的。然后，利用该模型获得了短链线性烷烃混合物在300 K下具有三种不同孔隙率ψ = 0.98、0.93和0.85以及三种孔隙宽度H = 1.02、1.70和2.38 nm的柱撑层状孔隙中的吸附等温线。模拟结果表明，较长链组分在低压下优先吸附，其吸附量随压力增加先增大后减小，而较短链组分在高压下仍被吸附。此外，柱撑层状材料对烷烃混合物中最长链组分的吸附选择性随气相中甲烷摩尔分数的增加而增加。柱撑层状材料对烷烃混合物中最长链组分的选择性也随孔隙宽度减小和孔隙率增加而增加。
