Discriminative Separation of Gases by a 鈥淢olecular Trapdoor鈥?Mechanism in Chabazite Zeolites

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• 作者：Jin Shang ; Gang Li ; Ranjeet Singh ; Qinfen Gu ; Kate M. Nairn ; Timothy J. Bastow ; Nikhil Medhekar ; Cara M. Doherty ; Anita J. Hill ; Jefferson Z. Liu ; Paul A. Webley
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：November 21, 2012
• 年：2012
• 卷：134
• 期：46
• 页码：19246-19253
• 全文大小：457K
• 年卷期：v.134,no.46(November 21, 2012)
• ISSN：1520-5126

文摘

Separation of molecules based on molecular size in zeolites with appropriate pore aperture dimensions has given rise to the definition of 鈥渕olecular sieves鈥?and has been the basis for a variety of separation applications. We show here that for a class of chabazite zeolites, what appears to be 鈥渕olecular sieving鈥?based on dimension is actually separation based on a difference in ability of a guest molecule to induce temporary and reversible cation deviation from the center of pore apertures, allowing for exclusive admission of certain molecules. This new mechanism of discrimination permits 鈥渟ize-inverse鈥?separation: we illustrate the case of admission of a larger molecule (CO) in preference to a smaller molecule (N₂). Through a combination of experimental and computational approaches, we have uncovered the underlying mechanism and show that it is similar to a 鈥渕olecular trapdoor鈥? Our materials show the highest selectivity of CO₂ over CH₄ reported to date with important application to natural gas purification.