Zeolites have tremendous potential as adsorbents for the selective separation and storage of gases in many industrial processes. The extent and selectivity of gas adsorption are dependent on a number of zeolite properties, such as pore diameter, accessible volume, and silicon-to-aluminum ratio. In addition, the existence of aluminum in the framework requires the presence of cations to maintain charge neutrality, and the identity of these extra-framework cations will also have a significant effect on adsorption. In this work, the continuous fractional component Monte Carlo method was used to examine the effect of the size and the charge of these cations on the adsorption of a variety of gases (CH₄, N₂, and CO₂) in two representative zeolite frameworks, clinoptilolite (heulandite) (CLI) and RHO at 298.15 K, using a range of pressures from 0.1 to 60 bar for a variety of mono- and divalent cations (Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺). Adsorption calculations in the single-cation systems revealed unique trends in the size and charge for each gas. To examine the combined effect of multiple cation types, adsorption was calculated at 0.5 and 30 bar in several two-cation systems, in which the effects of the size and charge were isolated and examined. The resulting adsorption varied linearly with the mole fraction of each two-cation mixture. A linear model is proposed to describe the loading of gases in CLI and RHO zeolites containing complex cation mixtures. Loading predicted by this model showed excellent agreement with direct simulation of gas adsorption in randomized seven-cation systems, suggesting that the adsorption effect of each cation is additive among the zeolite frameworks tested.

中文翻译：

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使用蒙特卡罗模拟研究斜发沸石和 RHO 沸石中气体吸附的阳离子依赖性：线性模型

沸石作为许多工业过程中气体选择性分离和储存的吸附剂具有巨大的潜力。气体吸附的程度和选择性取决于沸石的许多特性，例如孔径、可达到的体积和硅铝比。此外，骨架中铝的存在需要阳离子的存在来维持电中性，而这些骨架外阳离子的身份也会对吸附产生显着的影响。在这项工作中，使用连续分数组分蒙特卡罗方法研究了这些阳离子的尺寸和电荷对两种代表性沸石骨架中多种气体（CH ₄、N ₂和CO ₂ ）吸附的影响、斜发沸石（片沸石）(CLI) 和 RHO，温度为 298.15 K，压力范围为 0.1 至 60 bar，适用于各种单价和二价阳离子（Na ⁺、K ⁺、Cs ⁺、Mg ²⁺、Ca ^{2+ ）}、Sr ²⁺和Ba ²⁺ )。单阳离子系统中的吸附计算揭示了每种气体的尺寸和电荷的独特趋势。为了检查多种阳离子类型的综合效应，在几个双阳离子系统中计算了 0.5 和 30 bar 下的吸附，其中分离并检查了尺寸和电荷的影响。所得吸附随每种二阳离子混合物的摩尔分数线性变化。提出了一个线性模型来描述含有复杂阳离子混合物的 CLI 和 RHO 沸石中的气体负载。该模型预测的负载量与随机七阳离子系统中气体吸附的直接模拟非常一致，表明每种阳离子的吸附效果在测试的沸石框架中是相加的。