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.

The one-step purification of ethylene (C2H4) from ternary gas mixtures containing acetylene (C2H2), carbon dioxide (CO2), and C2H4 represents an efficient approach. It remains a significant challenge to simultaneously enhance the adsorption capacities of C2H2 and CO2. Herein, we reported a novel adsorbent, BFFOUR-TEPE-Cu, with compatible alignment of pore electro-fields. The one-connected BF4- anions provide more electronegative F atoms to reinforce the alignment of compatible electro-fields, thereby promoting the preferential adsorption of C2H2 and CO2 over C2H4. As a result, BFFOUR-TEPE-Cu exhibits a leading C2H2 capacity of 63.0 cm(3) g(-1) and C2H2/C2H4 (1/99, v/v) selectivity of 31.1 at 0.1 bar and 298 K. Computational studies reveal the favorable capture of both C2H2 and CO2 due to the compatible electron-fields. Dynamic breakthrough experiments demonstrate the exceptional capability for one-step production of high-purity C2H4 (>99.99 %) from ternary C2H2/CO2/C2H4 (1/9/90) gas mixture with a C2H4 productivity of 3.4 mol kg(-1).

The efficient separation of C2H2/CO2 mixtures is critical yet and remains challenging owing to their closely similar physical properties and molecular sizes. Herein, we report a novel flexible microporous adsorbent, Zn-SDBA-bpy (SDBA=4,4 '-sulfonyldibenzoic acid, bpy = 4,4 '-bipyridine), for molecular sieving of C2H2 from CO2. Zn-SDBA-bpy features contracted interlayer cavities with a highly negative electro-environment arising from abundant exposed oxygen atoms of SDBA. Charge transfers between C2H2 and the framework result in strong C2H2-host interactions that induce a selective gate-opening effect towards C2H2. Therefore, Zn-SDBA-bpy exhibits substantial C2H2 capture at low pressure (20.7 cm(3) g(-1) at 0.1 bar) while excluding CO2, demonstrating high C2H2/CO2 selectivity (490.2). Notably, Zn-SDBA-bpy features the lowest C2H2 gate-opening threshold (ca. 0.01 bar) among reported flexible adsorbents for C2H2/CO2 separation. Dynamic breakthrough experiments confirm its excellent C2H2/CO2 separation yielding high-purity C2H2 (>99.5 %) products. Modeling studies reveal the strong host-C2H2 interactions and underlying mechanisms of molecular sieving within Zn-SDBA-bpy.

Iso-butene (iso-C4H8) is an important raw material in chemical industry, whereas its efficient separation remains challenging due to similar molecular properties of C4 olefins. The ideal adsorbent should possess simultaneous high uptakes for 1,3-butadiene (C4H6) and n-butene (n-C4H8) counterparts, endowing high efficiency for iso-C4H8 separation in adsorption columns. Herein, a sulfate-pillared adsorbent, SOFOUR-DPDS-Ni (DPDS = 4,4' -dipyridyldisulfide), is reported for the efficient iso-C4H8 separation from binary and ternary C4 olefin mixtures. The rigidity in pore sizes and shapes of SOFOUR-DPDS-Ni exerts the molecular sieving of iso-C4H8, while exhibiting high C4H6 and n-C4H8 uptakes. The benchmark Henry's selectivity for C4H6/iso-C4H8 (2321.8) and n-C4H8/iso-C4H8 (233.5) outperforms most reported adsorbents. Computational simulations reveal the strong interactions for C4H6 and n-C4H8. Furthermore, dynamic breakthrough experiments demonstrate the direct production of high-purity iso-C4H8 (>99.9%) from C4H6/iso-C4H8 (50/50, v/v), n-C4H8/iso-C4H8 (50/50, v/v), and C4H6/n-C4H8/iso-C4H8 (50/15/35, v/v/v) gas-mixtures.

Flexible metal-organic framework (MOF) adsorbents commonly encounter limitations in removing trace impurities below gate-opening threshold pressures. Topology reconfiguration can fundamentally eliminate intrinsic structural flexibility, yet remains a formidable challenge and is rarely achieved in practical applications. Herein, a solvent-mediated approach is presented to regulate the flexible CuSnF6-dpds-sql (dpds = 4,4''-dipyridyldisulfide) with sql topology into rigid CuSnF6-dpds-cds with cds topology. Notably, the cds topology is unprecedented and first obtained in anion-pillared MOF materials. As a result, rigid CuSnF6-dpds-cds exhibits enhanced C2H2 adsorption capacity of 48.61 cm3 g-1 at 0.01 bar compared to flexible CuSnF6-dpds-sql (21.06 cm3 g-1). The topology transformation also facilitates the adsorption kinetics for C2H2, exhibiting a 6.5-fold enhanced diffusion time constant (D/r2) of 1.71 × 10-3 s-1 on CuSnF6-dpds-cds than that of CuSnF6-dpds-sql (2.64 × 10-4 s-1). Multiple computational simulations reveal the structural transformations and guest-host interactions in both adsorbents. Furthermore, dynamic breakthrough experiments demonstrate that high-purity C2H4 (>99.996%) effluent with a productivity of 93.9 mmol g-1 can be directly collected from C2H2/C2H4 (1/99, v/v) gas-mixture in a single CuSnF6-dpds-cds column.

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 cm(3) g(-1)) and CO2 (65 cm(3) g(-1)) at 1.0 bar and 298 K. Notably, the record-high C2H2 uptake (78 cm(3) 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.

Energy-efficient adsorptive separation shows great potential for the one-step production of high-purity ethylene (C2H4) from ternary C2 hydrocarbons. However, it remains a formidable challenge to fabricate high-performance adsorbents that exhibit simultaneous high selectivity (>2) towards acetylene/ethylene (C2H2/C2H4) and ethane/ ethylene (C2H6/C2H4). Herein, we report a pillar-layered metal-organic framework, Ni(sdba)(dabco)0.5 (H2sdba = 4,4 & PRIME;-sulfonyldibenzoic acid; dabco = 1,4-diazabicyclo [2.2.2] octane), for preferential trapping of C2H6 and C2H2 over C2H4. The abundant accessible binding sites endow Ni(sdba)(dabco)0.5 with outstanding C2H2/C2H4 (2.28) and C2H6/C2H4 (2.47) selectivity with high C2H6 (3.15 mmol g-1) and C2H2 (4.41 mmol g-1) uptake among porous materials reported for one-step C2H4 purification. Dynamic breakthrough experiments demon-strated the feasibility of producing high-purity C2H4 (>99.9%) from C2H2/C2H6/C2H4 gas-mixtures (1/1/1 and 1/9/90, v/v/v) in a single step. Computational simulations reveal that the aromatic-rich pore spaces, which decorated with accessible interlayer uncoordinated oxygen atoms of sulfonyl groups and alkyl functionalities, can provide multiple C-H & BULL;& BULL;& BULL;O, C-H & BULL;& BULL;& BULL;& pi;, and C-H & BULL;& BULL;& BULL;H interactions for selectively recognizing C2H6 and C2H2 over C2H4.