Optimized Separation of Acetylene from Carbon Dioxide and Ethylene in a Microporous Material

Abstract

Selective separation of acetylene (CH) from carbon dioxide (CO) or ethylene (CH) needs specific porous materials whose pores can realize sieving effects while pore surfaces can differentiate their recognitions for these molecules of similar molecular sizes and physical properties. We report a microporous material [Zn(dps)(SiF)] (UTSA-300, dps = 4,4'-dipyridylsulfide) with two-dimensional channels of about 3.3 Å, well-matched for the molecular sizes of CH. After activation, the network was transformed to its closed-pore phase, UTSA-300a, with dispersed 0D cavities, accompanied by conformation change of the pyridyl ligand and rotation of SiF pillars. Strong C-H···F and π-π stacking interactions are found in closed-pore UTSA-300a, resulting in shrinkage of the structure. Interestingly, UTSA-300a takes up quite a large amounts of acetylene (76.4 cm g), while showing complete CH and CO exclusion from CH under ambient conditions. Neutron powder diffraction and molecular modeling studies clearly reveal that a CH molecule primarily binds to two hexafluorosilicate F atoms in a head-on orientation, breaking the original intranetwork hydrogen bond and subsequently expanding to open-pore structure. Crystal structures, gas sorption isotherms, molecular modeling, experimental breakthrough experiment, and selectivity calculation comprehensively demonstrated this unique metal-organic framework material for highly selective CH/CO and CH/CH separation.

Lock‐and‐Key and Shape‐Memory Effects in an Unconventional Synthetic Path to Magnesium Metal–Organic Frameworks

“…[21] It is intriguing to find that CPM-107op can take up 136.7 cm 3 g À1 and 97.5 cm 3 g À1 of C 2 H 2 at 273 Ka nd 298 K( Figure S21), respectively.The uptake capacity at 298 Kishigher than some benchmark C 2 H 2 /CO 2 -separation materials such as UTSA-300 (67 cm 3 g À1 )and HOF-3 (47 cm 3 g À1 ). [22] Theisosteric heat for C 2 H 2 adsorption is also calculated to be in the range of 32-37 kJ mmol À1 ,a pparently larger than that of CO 2 (Figure 4). To evaluate the potential separation capability of CPM-107op,the ideal adsorbed solution theory (IAST) is applied to calculate the selectivity of C 2 H 2 /CO 2 in the equal mixture at 298 K (Figure S22, S23).…”

Induced Fit of C2H2 in a Flexible MOF Through Cooperative Action of Open Metal Sites

“…Supramolecular cages with asimilar binding effect in solution have been reported before; [5] however,i ti sc hallenging to develop porous solid materials to mimic such an induced-fit behavior for molecular recognition, which would be desired for many large-volume applications including industrial gas purification.Acetylene (C 2 H 2 )i sa ni mportant starting material for many chemical [6] and electronic [7] products.Y et, it is very reactive and may cause unwanted chemical reactions.S team cracking of hydrocarbons is the primary method for producing lighter alkenes and C 2 H 2 is an inevitable byproduct. [8] Recent studies have revealed that anumber of metal-organic frameworks [9] (MOFs) show an increased C 2 H 2 selectivity over other gas molecules through ligand functionalization, [10] pore size/shape customization, [11] surface polarization, [12] and, in particular, open-metal-sites incorporation. [13] Thel atter usually contributes more to the binding affinity because of the ability of C 2 H 2 to coordinate to the metal center.H owever, most of the MOF materials studied for C 2 H 2 selectivity have rigid frameworks whose dimensions barely change upon C 2 H 2 loading, which inevitably results in ad ecrease in binding affinity once the strongest adsorption sites for C 2 H 2 are occupied.To mimic an enzyme-like behavior,flexible MOFs whose scaffolds can self-adapt to match the size of the guest molecules are of particular interest.…”

Construction of a Stable Crystalline Polyimide Porous Organic Framework for C2H2/C2H4 and CO2/N2 Separation

“…The C 2 H 2 /C 2 H 4 adsorption selectivity of PAF-120 also outmatches those of somet ypical MOFs under the same conditions, such as Fe-MOF-74 (selectivity:1 .87), [9] M'MOF-2a (selectivity: 1.93), [52] and NOTT-300 (selectivity:2 .3), [10] but is outperformed by the selectivities of porousa dsorbents such as JCM-1 (selectivity:1 3.2), [16] SIFSIX-2-Cu-i (selectivity:4 1.01), [2] and UTSA-300a (selectivity > 10 4 ). [11]…”

“…[6][7][8][9][10][11][12][13][14][15] Some MOFs have been documented to be energy-efficient and environmentally friendly adsorbentsc apable of C 2 H 2 /C 2 H 4 and CO 2 /N 2 separation. [1,2,4,[7][8][9][10][11][12][13][14][15][16] Porous organic frameworks (POFs) or covalent organic frameworks (COFs), [17][18][19][20][21][22][23][24] an emerging family of porous materials, have attracted interest from the scientific communityf or their potentiali nm olecular separation, [25,26] catalysis, [27][28][29] drug delivery, [30,31] energy storage, [32][33][34][35] and many other applications. [36][37][38][39][40][41] In 2005, in pioneering work, crystalline COF-1 and COF-5 were fabricated b...…”