Chemical Vapor Deposition on Chabazite (CHA) Zeolite Membranes for Effective Post-Combustion CO2 Capture

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• 作者：Eunjoo Kim ; Taehee Lee ; Hyungmin Kim ; Won-Jin Jung ; Doug-Young Han ; Hionsuck Baik ; Nakwon Choi ; Jungkyu Choi
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：December 16, 2014
• 年：2014
• 卷：48
• 期：24
• 页码：14828-14836
• 全文大小：450K
• ISSN：1520-5851

文摘

Chabazite (CHA) zeolites with a pore size of 0.37 脳 0.42 nm² are expected to separate CO₂ (0.33 nm) from larger N₂ (0.364 nm) in postcombustion flue gases by recognizing their minute size differences. Furthermore, the hydrophobic siliceous constituent in CHA membranes can allow for maintaining the CO₂/N₂ separation performance in the presence of H₂O in contrast with the CO₂ affinity-based membranes. In an attempt to increase the molecular sieving ability, the pore mouth size of all silica CHA (Si-CHA) particles was reduced via the chemical vapor deposition (CVD) of a silica precursor (tetraethyl orthosilicate). Accordingly, an increase of the CVD treatment duration decreased the penetration rate of CO₂ into the CVD-treated Si-CHA particles. Furthermore, the CVD process was applied to siliceous CHA membranes in order to improve their CO₂/N₂ separation performance. Compared to the intact CHA membranes, the CO₂/N₂ maximum separation factor (max SF) for CVD-treated CHA membranes was increased by 鈭? fold under dry conditions. More desirably, the CO₂/N₂ max SF was increased by 鈭? fold under wet conditions at 鈭?0 掳C, a representative temperature of the flue gas stream. In fact, the presence of H₂O in the feed disfavored the permeation of N₂ more than that of CO₂ through CVD-modified CHA membranes and thus, contributed to the increased CO₂/N₂ separation factor.