Browsing by Author "Barbour, Leonard J."

Now showing 1 - 5 of 5
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    Breaking the trade-off between selectivity and adsorption capacity for gas separation
    (Elsevier Inc., 2021-11) Soumya, Naveen Kumar; Mukherjee, Nathan C.; Bezrukov, Andrey A.; Tan, Kui; Martins, Vinicius; Vandichel, Matthias; Pham, Tony; Van Wyk, Lisa M.; Oyekan, Kolade; Kumar, Amrit; Forrest, Katherine A.; Patil, Komal M.; Barbour, Leonard J.; Space, Brian; Huang, Yining; Kruger, Paul E.; Zaworotko, Michael J.
    The trade-off between selectivity and adsorption capacity with porous materials is a major roadblock to reducing the energy footprint of gas separation technologies. To address this matter, we report herein a systematic crystal engineering study of C2H2 removal from CO2 in a family of hybrid ultramicroporous materials (HUMs). The HUMs are composed of the same organic linker ligand, 4-(3,5-dimethyl-1H-pyrazol-4-yl)pyridine, pypz, three inorganic pillar ligands, and two metal cations, thereby affording six isostructural pcu topology HUMs. All six HUMs exhibited strong binding sites for C2H2 and weaker affinity for CO2. The tuning of pore size and chemistry enabled by crystal engineering resulted in benchmark C2H2/CO2 separation performance. Fixed-bed dynamic column breakthrough experiments for an equimolar (v/v = 1:1) C2H2/CO2 binary gas mixture revealed that one sorbent, SIFSIX-21-Ni, was the first C2H2 selective sorbent that combines exceptional separation selectivity (27.7) with high adsorption capacity (4 mmol·g−1).
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    Direct determination of enthalpies of sorption using pressure-gradient differential scanning calorimetry: CO2 sorption by Cu-HKUST
    (Wiley, 2020-06-01) Feldmann, Wesley K.; White, Kerry-Anne; Bezuidenhout, Charl X.; Smith, Vincent J.; Esterhuysen, Catharine; Barbour, Leonard J.
    Enthalpy of sorption (ΔH) is an important parameter for the design of separation processes using adsorptive materials. A pressure-ramped calorimetric method is described and tested for the direct determination of ΔH values. Combining a heatflow thermogram with a single sorption isotherm enables the determination of ΔH as a function of loading. The method is validated by studying CO2 sorption by the well-studied metal–organic framework Cu-HKUST over a temperature range of 288–318 K. The measured ΔH values compare well with previously reported data determined by using isosteric and calorimetric methods. The pressure-gradient differential scanning calorimetry (PGDSC) method produces reliable high-resolution results by direct measurement of the enthalpy changes during the sorption processes. Additionally, PGDSC is less labor-intensive and time-consuming than the isosteric method and offers detailed insight into how ΔH changes over a given loading range.
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    Microporosity of a guanidinium organodisulfonate hydrogen-bonded framework
    (Wiley, 2019-10) Brekalo, Ivana; Deliz, David E.; Barbour, Leonard J.; Ward, Michael D.; Friščić, Tomislav; Holman, Travis
    Guanidinium organosulfonates (GSs) are a large and well-explored archetypal family of hydrogen-bonded organic host frameworks that have, over the past 25 years, been regarded as nonporous. Reported here is the only example to date of a conventionally microporous GS host phase, namely guanidinium 1,4-benzenedisulfonate (p-G2BDS). p-G2BDS is obtained from its acetone solvate, AcMe@G2BDS, by single-crystal-to-single-crystal (SC-SC) desolvation, and exhibits a Type I low-temperature/pressure N2 sorption isotherm (SABET=408.7(2) m2 g−1, 77 K). SC-SC sorption of N2, CO2, Xe, and AcMe by p-G2BDS is explored under various conditions and X-ray diffraction provides a measurement of the high-pressure, room temperature Xe and CO2 sorption isotherms. Though p-G2BDS is formally metastable relative to the “collapsed”, nonporous polymorph, np-G2BDS, a sample of p-G2BDS survived for almost two decades under ambient conditions. np-G2BDS reverts to zCO2@p-G2BDS or yXe@p-G2BDS (y,z=variable) when pressure of CO2 or Xe, respectively, is applied.
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    Pressure-gradient sorption calorimetry of flexible porous materials : implications for intrinsic thermal management
    (Wiley, 2020-08) Feldmann, Wesley K.; Esterhuysen, Catharine.; Barbour, Leonard J.
    Thermal management is an important consideration for applications that involve gas sorption by flexible porous materials. A pressure-gradient differential scanning calorimetric method was developed to measure the energetics of adsorption and desorption both directly and continuously. The method was applied to the uptake and release of CO2 by the well-known flexible metal–organic frameworks MIL-53(Al) and MOF-508b. High-resolution differential enthalpy plots and total integral enthalpy values for sorption allow comprehensive assessment of the thermal behavior of the materials throughout the entire sorption process. During adsorption, the investigated materials display the ability to offset exothermic adsorption enthalpy against endothermic structural transition enthalpy, and vice versa during desorption. The results show that flexible materials offer reduced total integral heat over a working range when compared to rigid materials.
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    Tuning extreme anisotropic thermal expansion in 1D coordination polymers through metal selection and solid solutions†
    (Royal Society of Chemistry, 2021-07) Van Wyk, Lisa M.; Loots, Leigh; Barbour, Leonard J.
    The thermal expansion behaviour of a series of 1D coordination polymers has been investigated. Variation of the metal centre allows tuning of the thermal expansion behaviour from colossal positive volumetric to extreme anomalous thermal expansion. Preparation of solid solutions increased the magnitude of the anomalous thermal expansion further, producing two species displaying supercolossal anisotropic thermal expansion (ZnCoCPHTαY2 = −712 MK−1, αY3 = 1632 MK−1 and ZnCdCPHTαY2 = −711 MK−1, αY3 = 1216 MK−1).