Screening Metal-Organic Frameworks by Analysis of Transient Breakthrough of Gas Mixtures in a Fixed Bed Adsorber
Screening Metal-Organic Frameworks by Analysis of Transient Breakthrough of Gas Mixtures in a Fixed Bed Adsorber
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DOI：
10.1021/jp202203c
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发表时间：
2011-07-07
影响因子：
3.7
通讯作者：
Long, Jeffrey R.
中科院分区：
文献类型：
--
作者：
Krishna, Rajamani;Long, Jeffrey R.
金属有机骨架（MOFs）为分离各种混合物提供了相当大的潜力，这些混合物在CO2捕获和H-2纯化等应用中非常重要。鉴于已合成的MOFs数量巨大，需要一种可靠的程序，用于比较筛选和排序MOFs在变压吸附装置中的预期性能。为此，最常用的指标是吸附选择性和工作容量。在这里，我们建议一个额外的度量比较的MOF是基于分析的瞬态响应的吸附器的一个步骤输入的气体混合物。对于从吸附器排出的气体混合物的选定纯度，可以定义和确定无量纲穿透时间τ（break）;该度量确定了所需再生的频率并影响PSA单元的生产率。τ（断裂）的值由选择性和容量度量决定。通过进行用于分离CO2/H-2，CO2/CH 4，CH 4/H-2，和CO2/CH 4/H-2混合物，我们比较了tau（断裂）的值，以突出MOFs相对于常规使用的吸附剂如沸石NaX的一些重要优势。对于一个给定的分离责任，这种比较提供了一个更现实的排名MOFs比提供的选择性或能力指标单独。我们的结论是，突破计算可以提供一个必要的工具，筛选MOFs。
Metal-organic frameworks (MOFs) offer considerable potential for separating a variety of mixtures that are important in applications such as CO2 capture and H-2 purification. In view of the vast number of MOFs that have been synthesized, there is a need for a reliable procedure for comparing screening and ranking MOFs with regard to their anticipated performance in pressure swing adsorption (PSA) units. For this purpose, the most commonly used metrics are the adsorption selectivity and the working capacity. Here, we suggest an additional metric for comparing MOFs that is based on the analysis of the transient response of an adsorber to a step input of a gaseous mixture. For a chosen purity of the gaseous mixture exiting from the adsorber, a dimensionless breakthrough time tau(break) can be defined and determined; this metric determines the frequency of required regeneration and influences the productivity of a PSA unit The values of tau(break) are dictated both by selectivity and by capacity metrics By performing transient adsorber calculations for separation of CO2/H-2, CO2/CH4, CH4/H-2, and CO2/CH4/H-2 mixtures, we compare the values of tau(break) to highlight some important advantages of MOFs over conventionally used adsorbents such as zeolite NaX. For a given separation duty, such comparisons provide a more realistic ranking of MOFs than afforded by either selectivity or capacity metrics alone. We conclude that breakthrough calculations can provide an essential tool for screening MOFs.