Structural Chemistry, Flexibility, and CO 2 Adsorption Performance of Alkali Metal Forms of Merlinoite with a Framework Si/Al Ratio of 4.2
Structural Chemistry, Flexibility, and CO 2 Adsorption Performance of Alkali Metal Forms of Merlinoite with a Framework Si/Al Ratio of 4.2
复制标题
骨架Si/Al比为4.2的碱金属形式的橄榄石的结构化学、柔韧性和CO 2 吸附性能
DOI：
10.1021/acs.jpcc.1c08296
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Bruce E
中科院分区：
文献类型：
--
作者：
Bruce E
显示出骨架柔性的小孔沸石，例如merlinoite（拓扑类型MER），具有选择性吸附包括CO2的小气体分子的高潜力。在298 K下测定了Si/Al = 4.2的钠、钾和铯交换型钙铝沸石对CO2的吸附性能，并利用原位PXRD研究了它们对脱水和CO2吸收的结构响应。Na-和Cs-形式在脱水后从宽孔转化为窄孔形式，而K-形式保持在宽孔形式。Na-和Cs-形式表现出阶梯式CO2吸附等温线，与呼吸行为和从窄孔到宽孔相的膨胀一致，而K6.2-MER始终保持在宽孔结构中。K-和Cs-型的同步辐射PXRD揭示了CO2吸附对阳离子位分布和骨架构型的影响。与具有较低Si/Al的那些相比，MER（4.2）的所有阳离子形式显示出增强的Ar吸附动力学，并且K6.2-MER（4.2）的宽孔结构显示出对Ar和CO2的特别快速的吸附。K6.2-MER（4.2）上的穿透曲线表明，在流动的CO2/CH 4混合物中，即使在具有氧化铝粘合剂的颗粒形式中，CO2与CH 4也能良好分离。
Small pore zeolites that show framework flexibility, such as merlinoite (topology type MER), possess a high potential for the selective adsorption of small gas molecules including CO2. The CO2adsorption properties of Na-, K-, and Cs-exchanged forms of a merlinoite zeolite with Si/Al = 4.2 have been measured at 298 K, andin situPXRD was used to follow their structural response to dehydration and CO2uptake. The Na- and Cs-forms convert from a wide-pore to a narrow-pore form upon dehydration, while the K-form remains in the wide-pore form. The Na- and Cs-forms exhibit stepped CO2adsorption isotherms, consistent with breathing behavior and expansion from narrow- to wide-pore phases, while K6.2-MER remains in the wide-pore structure throughout. Synchrotron PXRD of the K- and Cs-forms reveals the effects of CO2adsorption on the cation site distributions and the framework configuration. All cation forms of MER (4.2) show enhanced adsorption kinetics for Ar compared to those with lower Si/Al, and the wide-pore structure of K6.2-MER (4.2) shows particularly rapid sorption for both Ar and CO2. Breakthrough curves over K6.2-MER (4.2) demonstrate good separation of CO2from CH4in flowing CO2/CH4mixtures, even in pelletized form with an alumina binder.