The purification of propene from the propene/propane binary mixture is one of the most important and challenging separation processes in the chemical industry. In this study, a cobalt‐based pillar‐layer metal–organic framework, Co(AIP)(BPY)0.5, was synthesized. It exhibited excellent water and moisture stability and efficient C3H6/C3H8 separation performance. At 298 K and 100 kPa, the adsorption capacity of C3H6 was 1.99 mmol/g and the IAST adsorption selectivity was 21, which has exceeded most investigated MOFs adsorbents. The cyclic breakthrough experiments of C3H6/C3H8 binary mixture confirmed its efficient dynamic separation property and excellent recyclability. The molecular simulation showed that the C3H8 molecules with multiple binding sites (C─H) were restricted at the middle of the one‐dimensional channel. Compared with C3H6, the large steric hindrance of C3H8 caused lower diffusion rate (with a C3H6/C3H8 kinetic selectivity of 29.7, at 303 K) in the narrow pore system of 1, which has been confirmed by the kinetic adsorption experiments.
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.
The developments of high‐performance adsorbents have attracted ever‐increasing attention in the separation of ethane/ethylene (C2H6/C2H4) mixtures. In this work, a series of ultra‐stable C2H6‐selective metal–organic frameworks (MOFs), PCN‐250, and its bimetal version PCN‐250(Fe2M2+, M2+ = Ni2+, Co2+, Zn2+, Mn2+), were synthesized to investigate the influence of metal compositions on the C2H6‐selective performance. Among the five materials, at 298 K and 100 kPa, PCN‐250(Fe2Co) showed the largest C2H6 uptake (6.21 mmol/g) while PCN‐250(Fe2Zn) exhibited the highest C2H6/C2H4 ideal adsorption solution theory (IAST) selectivity (1.70). The molecular simulation revealed that the introduced metal ions have different influences on the atomic partial charge within the framework which varied the framework adsorption affinities toward C2H6/C2H4 molecules. Moreover, the research on PCN‐250(Fe2Zn) suggested that the increased positive partial charge of metal sites together with a decreased charge density of benzene ring (BR) sites from the organic ligands will be beneficial to improve the desired C2H6 selectivity.
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