Improving CH4/N2 selectivity within isomeric Al-based MOFs for the highly selective capture of coal-mine methane |
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| Authors: | Daofei Lv Ying Wu Jiayu Chen Yuanhua Tu Yinuo Yuan Houxiao Wu Yongwei Chen Baoyu Liu Hongxia Xi Zhong Li Qibin Xia |
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| Affiliation: | 1. School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China;2. School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, China |
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| Abstract: | Selectively separating CH4 from N2 in coal-mine methane is significantly important in the chemical industry, but challenging and energy-intensive. Using porous materials as adsorbents can separate CH4/N2 mixtures with low energy consumption, but most adsorbents encounter the problem of poor separation selectivity. Here, we propose a strategy for improving CH4/N2 selectivity by controlling pore wall environment in two isomeric Al-based metal–organic frameworks (MOFs) with four highly symmetric polar sites for strengthened adsorption affinity toward CH4 over N2. At 298 K and 100 kPa, CAU-21-BPDC with four highly symmetric polar sites in the pore walls exhibits 2.4 times higher CH4/N2 selectivity than CAU-8-BPDC without four highly symmetric polar sites. Gas adsorption isotherms, CH4/N2 selectivity calculations, Qst of CH4, interaction energy calculations, adsorption density distributions of CH4 and N2, and breakthrough curves reveal that CAU-21-BPDC is a potential candidate for selective capture coal-mine methane. |
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| Keywords: | CH4/N2 separation coal-mine methane improving selectivity isomeric MOFs symmetric polar sites |
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