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Postsynthetic Strategy To Prepare ACN@Cu-BTCs with Enhanced Water Vapor Stability and CO2/CH4 Separation Selectivity

Lin, Zhedong, Lv, Zhenqiang, Zhou, Xin, Xiao, Huiyu, Wu, Junliang, Li, Zhong
Industrial & engineering chemistry process design and development 2018 v.57 no.10 pp. 3765-3772
Fourier transform infrared spectroscopy, adsorption, carbon dioxide, copper, crystal structure, methane, process design, water vapor
Cu-BTC, a commercially available MOF with great potential in gas adsorption and separation, is vulnerable to moisture, hindering its practical application. We propose a postsynthetic strategy to prepare ACN@Cu-BTCs with enhanced water vapor stability and CO₂/CH₄ selectivity. Successful grafting of ACN was evidenced by FT-IR spectra, which completely inhibited the moisture-induced adsorptive capacity degeneration of ACN₁/₁@Cu-BTC at RH = 55% for CO₂ capture. The water vapor stability experiments showed that after being exposed to 55% RH for 20 days, Cu-BTC lost its crystallinity and CO₂ adsorption capacity, while ACN₁/₃@Cu-BTC preserved 88% of its original CO₂ capacity. In addition, ACN₁/₃@Cu-BTC showed a high CO₂ capacity of 4.32 mmol/g under ambient conditions and inherited the decent CO₂/CH₄ adsorption selectivity from Cu-BTC. DFT calculation ascribed such an enhanced water vapor stability to the protection of Cu sites by ACN, which is worth further exploitation in enhancing the water vapor stability of other MOFs with unsaturated metal sites.