Browsing by Author "D'Alessandro, DM"
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- ItemConcentration-dependent binding of CO2 and CD4 in UiO-66 (Zr)(American Chemical Society, 2015-04-02) Chevreau, H; Liang, WB; Kearley, GJ; Duyker, SG; D'Alessandro, DM; Peterson, VKPorous metal–organic frameworks (MOFs) have emerged as promising materials for the capture of carbon dioxide (CO2) and its separation from methane (CH4) during the industrially important “sweetening” of sour natural-gas. The excellent thermal and chemical stability of the highly porous UiO-66(Zr) material, combined with good selectivity for CO2 over CH4, makes this material a prime candidate for such applications. Using a combination of neutron powder-diffraction and density-functional theory, we examine the details of the binding of CO2 and CH4 in UiO-66(Zr) over the industrially relevant 3.6–9.0 mmol/g concentration range, corresponding to the material that is half to fully saturated with CO2. This work builds on the previously reported preferred site for CO2 and CH4 in UiO-66(Zr), establishing further sites and determining the strength and nature of the guest–host interaction at these. We find the UiO-66(Zr)···CO2 interactions are significantly affected by the concentration of CO2 as the binding of CO2 is enhanced by interguest interactions. © 2015 American Chemical Society
- ItemGuest–host complexes of TCNQ and TCNE with Cu3(1,3,5-benzenetricarboxylate)2(American Chemical Society, 2017-11-02) Usov, PM; Jiang, H; Chevreau, H; Peterson, VK; Leong, CF; D'Alessandro, DMA combined spectroscopic and structural study was undertaken to investigate the nature of the incorporation of the electron acceptor guest 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the closely related guest tetracyanoethylene (TCNE) into the host porous framework [Cu3(BTC)2] (BTC = 1,3,5-benzenetricarboxylate)—a guest–host system recently shown to be highly conductive. We find that the guest concentration in the system can be modulated via the synthesis reaction time and temperature. A suite of spectroscopic, X-ray and neutron powder diffraction, and density functional theory techniques revealed the mechanism of guest binding within the framework host, including the guest redox states. This work provides insights into the way that electrical conductivity arises in porous framework host–guest systems and contributes to understanding how fine-tuning framework properties influences conductivity. © 2017 American Chemical Society
- ItemMechanism and kinetics of carbon dioxide adsorption in metal organic frameworks(Australian Institute of Nuclear Science and Engineering (AINSE), 2012-11-07) Das, A; Duyker, SG; Peterson, VK; D'Alessandro, DMMetal-organic frameworks (MOFs) are a class of porous material possessing high crystallinity, which may be specifically targeted to carbon dioxide (CO2) capture and separation in order to meet global targets associated with the reduction of CO2 emissions from industrial sources. The selectivity of MOFs for CO2 uptake over other gases (e.g. N2) may be improved through the introduction of functional groups known to interact with carbon dioxide, e.g. amines, which react with CO2 in an acid- base mechanism. The specific mechanisms and kinetics of CO2 adsorption in such materials are not widely understood, but may be elucidated using neutron diffraction techniques. We have previously employed neutron diffraction in preliminary experiments to investigate the in situ concentration-dependent behaviour of CO2 adsorption in [Ni2(dobdc)] (dobdc = 2,5-dioxido-1,4-benzenedicarboxylate) and our recently published piperazine-functionalised framework [Ni2(dobdc)(pip)0.5]. We are further expanding our repertoire of materials and types of functional groups investigated using this method; in particular, we are investigating the interaction of CO2 molecules with pendant functional groups such as sulfones, primary amines and secondary amines. The nature of these interactions may be explored using X-ray diffraction, gas sorption, gravimetric analysis using mixed gas streams and infrared spectroscopy; however, neutron diffraction presents a powerful and unique in situ technique to probe the temperature- and concentration-dependent behaviour of CO2 binding to identify intermediate binding species, fully explore the binding mode of CO2 and investigate structural effects in the adsorbate material. Mixed gas (CO2/N2) experiments will be used to explore the specificity of the host-guest behaviour in these functionalised frameworks. Based upon this data, it will be possible explore specific chemical factors contributing to selective CO2 capture, and in doing so contribute to the design of new materials or improve upon existing ones for CO2 uptake.
- ItemNeutron diffraction and in situ gas-loading investigations of functional MOFs for energy-relevant gas separations(Australian Institute of Nuclear Science and Engineering (AINSE), 2012-11-08) Duyker, SG; Peterson, VK; Ogilvie, SH; Turner, DR; Hill, MR; D'Alessandro, DM; Kepert, CJIntense research is currently directed towards realising metal-organic frameworks (MOFs) for industrially-applied gas separation and storage due to their unique structural properties, including: robustness; thermal and chemical stability; unprecedented internal surface area; and high void volume. A particular focus of current research is the development of MOFs for the separation of CO, from the other components of flue gas in fossil-fuelled power plants. The use of NPD to study gas adsorption in framework materials is a relatively new but growing field. Structural measurements, which show the arrangement of both the host and guest, allow derivation of the nature of the host-guest interaction, and the host's response to the guest. The capability to perform these measurements, with accurate gas dosing and temperature control, has recently been realised at ANSTO's Bragg Institute. Using these techniques, we have investigated the adsorption mechanisms of a number of gases in selected new and established MOFs that display impressive selectivity for specific gases. The location and orientation of industrially-relevant gases including D2, 02, CO2, and CD4, within their crystal structures provide insights into the modes of binding, which will help to tune the materials' performance and benefit the design and development process for the next generation of materials.
- ItemTuning pore size in a zirconium–tricarboxylate metal–organic framework(Royal Society of Chemistry, 2014-06-04) Liang, WB; Chevreau, H; Ragon, F; Southon, PD; Peterson, VK; D'Alessandro, DMThe water-stable zirconium–tricarboxylate series of frameworks, [Zr6O4(OH)4(X)6(btc)2]·nH2O, where X = formate (F), acetate (A), or propionate (P), exhibit tunable porosity by virtue of systematic modulation of the chain length of the monocarboxylate ligand X. This modification not only impacts the pore size of the framework, but provides an important avenue for the construction of mixed-linker MOFs. © 2014, The Royal Society of Chemistry.