Separation of p‐Divinylbenzene by Selective Room‐Temperature Adsorption Inside Mg‐CUK‐1 Prepared by Aqueous Microwave Synthesis

Abstract

An ew Mg II -based version of the porous coordination polymer CUK-1 with one-dimensional pore structure was prepared by microwave synthesis in water.M g-CUK-1 is moisture-stable,t hermally stable up to 500 8 8C, and shows unusual reversible soft-crystal behavior:d ehydrated single crystals of the material selectively adsorb ar ange of organic molecules at ambient temperature and pressure.B oth polar and apolar aromatic compounds,including pyridine,benzene, p-xylene,a nd p-divinylbenzene (p-DVB), are all readily adsorbed, while other isomers from complex mixtures of xylenes or DVBs are selectively excluded. The solvent-loaded structures have been studied by single-crystal X-ray diffraction. Time-dependent liquid sorption experiments using commercially available DVBd emonstrate ah igh and rapid selective adsorption of p-DVB and exclusion of m-DVB and ethylvinylbenzene isomers.A number of porous coordination polymers (PCPs) have been shown to possess the ability to effectively separate complex mixtures of gases [1] and, less commonly,o fl iquid hydrocarbons.[2] Thel atter represents at angible application for such materials,e specially to achieve separations that cannot be easily performed using common large-scale separation methods (e.g., column chromatography,ion exchange, fractional distillation). [3,4] One such example concerns the separation of isomers of divinylbenzene (DVB): p-DVBi s important in the manufacture of cross-linked styrene polymers,w hich, paradoxically,a re utilized in the manufacturing of ion-exchange resins.[4] DVBi sp repared by dehydrogenation of crude mixtures of o-, m-, and p-diethylbenzene. Commercially available DVBconsists of approximately 80 % m-and p-DVB along with the products of partial dehydrogenation, m-and p-ethylvinylbenzene (EVB). From an industrial standpoint, pure p-DVB is most preferred for the formation of ordered cross-linked styrene/p-DVB copolymers,but largescale separation approaches have proven to be inefficient. [5] In 2007, we published the discovery of ah ighly porous cobalt(II)-based coordination polymer named CUK-1, which has received significant attention because of its exceptional ability to separate complex gas mixtures.[6] CUK-1 is based on 2,4-pyridinedicarboxylic acid (2,4-pdc) and contains onedimensional channels with square pore windows.The material was shown to be highly robust, owing to the presence of infinite one-dimensional metal hydroxide chains that support ac orrugated wall structure.O ne potential drawback of transition-metal-based materials is the potential for slow hydrolytic decomposition. Ongoing efforts to determine methods for the preparation of more highly stable phases of CUK-1 using alternative metals have ultimately yielded afast, reproducible,and high-yielding method for the production of aM g II analogue.M g-CUK-1 is conveniently prepared in water with ar apid and energy-efficient microwave(mw)-assisted method that yields ac rystalline product in only 35 min at 200 8 8C. Replacement of CoII with Mg II was our ultimate goal, ...

Porous Metal–Organic Framework CUK-1 for Adsorption Heat Allocation toward Green Applications of Natural Refrigerant Water

“…The M-CUK-1 materials can also be easily tuned in terms of chemical modulation of the inorganic structural components, i.e., by obtaining isostructural materials based on 3s-or 3d-metals, Mg 2+ , Co 2+ or Ni 2+ . 32,33 This assertion is demonstrated and confirmed by a combined experimental and computational investigation that integrates gravimetric sorption testing, thermodynamic calculations of cooling/heating performances and molecular simulations. This work equally aims to investigate the energyefficient water sorption properties of M-CUK-1 materials that could be potentially applied to thermal energy storage as well as for adsorption-driven heating/cooling.…”

“…[31][32][33] The channels are filled with water molecules that can be fully removed by heating and/or under vacuum, without loss of crystallinity, as originally determined by single crystal X-ray diffraction (SCXRD) and bulk powder X-ray diffraction (PXRD) studies. 31 Somewhat more recently, upon experimentation with other M(II) salts, two further analogues, Ni-CUK-1 32 and Mg-CUK-1, 33 were also identified using NiCl2 in a 3:2:9 molar ratio of NiCl2:2,4-pdcH2:KOH, or Mg(NO3)2 in a 3:2:8 molar ratio of Mg(NO3)2:2,4-pdcH2:KOH, respectively, by analogous hydrothermal heating methods between 200-220 °C. Both the Ni and Mg materials are isostructural with the Co phase and the lattice connectivity is identical for the three frameworks.…”

Flexibility of Metal-Organic Framework Tunable by Crystal Size at the Micrometer to Submillimeter Scale for Efficient Xylene Isomer Separation

“…Moreover, with a much smaller crystal size, the adsorption rate of 1B is ultrafast (within 2 min, Figure 4(b) and S17) and its selectivity is sim-ilar to that of 3B (Figure 4(a) and S18). To the best of our knowledge, MOF adsorbents reported in the literature require at least hours to achieve satisfactory batch adsorption of xylene isomers [2,32,33,37]. It is worth noting that the crystal size of 1B is still at the normal micrometer scale, which is advantageous for avoiding common problems of nanomaterials, such as instability and difficulty of synthesis.…”

Remarkable adsorptive removal of nitrogen-containing compounds from a model fuel by a graphene oxide/MIL-101 composite through a combined effect of improved porosity and hydrogen bonding

“…These functionalities include high porosity, organic-inorganic functional sites, and easy modifiability for specific purposes. The applicability and stability of MOFs in adsorption conditions make MOFs one of the most promising groups of materials for several adsorption-related processes [18][19][20][21][22][23][24][25]. Several reports have been published on ADN [26][27][28][29] and ADS [30][31][32][33][34][35][36][37][38] with pristine or modified MOFs that have shown successful removal of NCCs and SCCs from fuels.…”