Efficient adsorptive separation of propene over propane through a pillar‐layer cobalt‐based metal–organic framework

Abstract

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.

Designer Metal–Organic Frameworks for Size‐Exclusion‐Based Hydrocarbon Separations: Progress and Challenges

“…Very recently, Xia et al reported the separation of propane and propylene on a cobalt‐based pillar‐layer MOF, Co(aip)(bpy) 0.5 (aip = 5‐aip aminoisophthalic acid, bpy = 4,4′‐bipyridine), with 1D channel of ≈4.5 Å in diameter. [ 82 ] Equilibrium adsorption isotherms displayed that it adsorbed 8.5 wt% of propylene but substantially less propane (≈2 wt%) which is close to a case of selective size exclusion. Exploration of its adsorption kinetics confirmed that the adsorption rate for propylene was much faster than that of propane, with a kinetic selectivity of ≈30.…”

Crystal engineering of porous coordination networks for C3 hydrocarbon separation

“…Van der Waals and supramolecular interactions can also play a role in selective recognition of C3 HC molecules as exemplified by Co(AIP)(BPY) 0.5 (5-aminoisophthalic acid [AIP]; 4,4'-bipyridine [BPY]) as reported by Qibin Xia's group. 109 As presented in Figure 6…”

“…Other examples of C 3 H 6 from C 3 H 8 separation include ITQ-12, CPL-1, Y-abc, NJU-Bai8, Zn 2 (5-AIP) 2 (BPY), MIL-100(Fe), AGTU-3a, MAF-23-O, Co(AIP)(BPY) 0.5 , MCF-56/57, ZU-32, SIFSIX-2-Cu-i. [91][92][93][94][95][106][107][108][109][110][111] All the aforementioned PCNs are selective for C 3 H 6 over C 3 H 8 ; reports of inverse selectivity, C 3 H 8 -selective materials, are rare. [112][113][114][115] In 2020, Yang et al 113…”

“…Van der Waals and supramolecular interactions can also play a role in selective recognition of C3 HC molecules as exemplified by Co(AIP)(BPY) 0.5 (5‐aminoisophthalic acid [AIP]; 4,4'‐bipyridine [BPY]) as reported by Qibin Xia's group 109 . As presented in Figure 6, C 3 H 8 molecules are weakly bound in a single binding site by six weak C−H···π interactions between six hydrogen atoms of the C 3 H 8 molecules and the BPY ligands.…”

Exploiting thermodynamic-kinetic synergetic effect for C3H6/C3H8 separation in pillar-layer MOFs

“…5 As a result, the separation of C 3 H 6 /C 3 H 8 mixtures is an inevitable process to obtain polymer-grade (> 99.5%) C 3 H 6 . Due to their close similarity in physical properties including the small difference in boiling points (226 K for C 3 H 6 and 231 K for C 3 H 8 ), close molecular sizes (6.5 × 4.0 × 3.8Å 3 of C 3 H 6 and 6.8 × 4.2 × 3.8Å 3 of C 3 H 8 ), and extremely close relative volatility (1.09-1.15), 2,6 C 3 H 6 /C 3 H 8 separation is listed as one of the seven chemical separations to change the world. 7 To date, industrial separation of C 3 H 6 and C 3 H 8 is commonly achieved by the established energy-intensive cryogenic distillation method that requires to be performed under very harsh operation conditions, including more than 180 theoretical trays, reflux ratio as high as 12-20, ultra-low operation temperature of -30°C, and high operation pressure of 30 bar.…”