Search

Selective removal of acetylene (C2H2) from ethylene (C2H4) presents considerable challenges due to their extremely close molecular size and physical properties. Herein, we successfully prepared two novel isomorphous interpenetrated adsorbents, i.e. Zn-SDBA-dpe and Zn-SDBA-bpy (SDBA = 4,4′-sulfonyldibenzoic acid, dpe = 4,4′-vinylenedipyridine, bpy = 4,4′-bipyridyl), for molecular sieving of C2H2 from C2H4. The uniform interpenetration of Zn-SDBA-bpy possessing contracted and suitable cavities only allows the diffusion of C2H2, while excluding C2H4 molecules. As a result, Zn-SDBA-bpy exhibits an exceptional C2H2/C2H4 uptake ratio of 11.93, and remarkable selectivities of 936.7 and 229.9 for the 50/50 and 1/99 C2H2/C2H4 mixtures, respectively. Dynamic breakthrough experiments further corroborate its superior feasibility for C2H2/C2H4 separation. Moreover, computational simulations reveal the multiple host–guest interactions for C2H2 and the underlying mechanism of molecular sieving within Zn-SDBA-bpy. [ABSTRACT FROM AUTHOR]

One‐step separation of C2H4 from ternary gas mixtures containing acetylene (C2H2), ethylene (C2H4), and carbon dioxide (CO2) represents a great challenge in chemical industry. Herein, we report the electro‐field alignment in a novel anion‐pillared MOF (SIFSIX‐TEPE‐Cu) for benchmark C2H4 separation from C2H2/CO2/C2H4 gas mixtures. The semi‐cage cavities featuring capped facets generated negative potentials along anion pillars and compensatory positive‐charged electro‐fields along organic ligands (TEPE) that facilitate specific recognitions of C2H2 and CO2 over C2H4. As a result, SIFSIX‐TEPE‐Cu exhibits high adsorption capacities for C2H2 (123 cm3 g−1) and CO2 (65 cm3 g−1) at 1.0 bar and 298 K. Notably, the record‐high C2H2 uptake (78 cm3 g−1) at 0.01 bar and remarkable C2H2/C2H4 selectivity (615.2) renders benchmark trace C2H2 removal ability. Dynamic breakthrough experiments demonstrate the benchmark productivity for high‐purity C2H4 (>99.995%) of 194.7 mol kg−1 and 5.96 mol kg−1 from binary C2H2/C2H4 (1/99, v/v) and ternary C2H2/CO2/C2H4 (1/9/90, v/v/v) gas mixtures. [ABSTRACT FROM AUTHOR]

Olefin/paraffin separations are among the most energy-intensive processes in the petrochemical industry, with ethylene being the most widely consumed chemical feedstock. Adsorptive separation utilizing molecular sieving adsorbents can optimize energy efficiency, whereas the size-exclusive mechanism alone cannot achieve multiple olefin/paraffin sieving in a single adsorbent. Herein, an unprecedented sieving adsorbent, BFFOUR-Cu-dpds (BFFOUR = BF4-, dpds = 4,4'-bipyridinedisulfide), is reported for simultaneous sieving of C2-C4 olefins from their corresponding paraffins. The interlayer spaces can be selectively opened through stronger guest-host interactions induced by unsaturated C = C bonds in olefins, as opposed to saturated paraffins. In equimolar six-component breakthrough experiments (C2H4/C2H6/C3H6/C3H8/n-C4H8/n-C4H10), BFFOUR-Cu-dpds can simultaneously divide olefins from paraffins in the first column, while high-purity ethylene (> 99.99%) can be directly obtained through the subsequent column using granular porous carbons. Moreover, gas-loaded single-crystal analysis, in-situ infrared spectroscopy measurements, and computational simulations demonstrate the accommodation patterns, interaction bonds, and energy pathways for olefin/paraffin separations. Olefin/paraffin separations are challenging in chemical industry. Here, authors report a sieving adsorbent for separating C2-C4 olefins from counterpart paraffins. The interlayer spaces are selectively opened via stronger guest-host interactions induced by olefins, as opposed to saturated paraffins. [ABSTRACT FROM AUTHOR]

Adsorbents executing molecular sieving mechanisms for the efficient separation of n‐hexane (C6) alkane isomers require delicate pore size control, but afford unsatisfactory single‐component separations according to their branch degrees. Herein, we report a novel oxygenate‐pillared microporous adsorbent, MoOFOUR‐Co‐tpb, ([Co(tpb)2MoO4], tpb = 1,2,4,5‐tetra(pyridin‐4‐yl) benzene), with three gourd‐shaped channels for dual pore‐size sieving of C6 isomers. In particular, MoOFOUR‐Co‐tpb excludes 2,2‐dimethylbutane, while 3‐methylpentane (3MP) can enter one channel showing a high uptake of 82.6 mg g−1, contrasting to the n‐hexane (nHEX) adsorption by two channels (136 mg g−1). This dual pore‐size control strategy renders a record high equilibrium–kinetic combined selectivity for nHEX/3MP (30.2). Moreover, three‐ and five‐component breakthrough experiments confirm the practical separation performances and cycling stability. Multiple theoretical simulations reveal the separation mechanism and adsorption sites. [ABSTRACT FROM AUTHOR]

Molecular sieving of propylene (C 3 H 6 ) from propane (C 3 H 8 ) is highly demanded for C 3 H 6 purification. However, delicate control over aperture size to achieve both high C 3 H 6 uptake and C 3 H 6 /C 3 H 8 selectivity with low cost remains a significant challenge. Herein, a green and scalable approach is reported for preparing an isomeric CALF-20 adsorbent, termed as NCU-20, using water as the only solvent with a cost of $10 per kilogram. NCU-20 features a contracted pore size (4.2 × 4.7 Å 2 ) compared to CALF-20 (5.2 × 5.7 Å 2 ), which enables molecular sieving of C 3 H 6 (4.16 × 4.65 Å 2 ) from C 3 H 8 (4.20 × 4.80 Å 2 ). Notably, NCU-20 exhibits record-high C 3 H 6 adsorption capacity (94.41 cm 3  cm -3 ) at 298 K and 1.0 bar, outperforming all C 3 H 6 /C 3 H 8 molecular sieving adsorbents. The sieving performances of C 3 H 6 /C 3 H 8 are well maintained at elevated temperatures. Therefore, a delicate balance between C 3 H 6 adsorption capacity (91.62 cm 3  cm -3 ) and C 3 H 6 /C 3 H 8 selectivity (uptake ratio of 22.2) is obtained on NCU-20 at 298 K and 0.5 bar. Furthermore, dynamic breakthrough experiments demonstrate a high productivity of 65.39 cm 3  cm -3 for high-purity C 3 H 6 (>99.5%) from an equimolar C 3 H 6 /C 3 H 8 gas-mixture., (© 2024 Wiley‐VCH GmbH.)