Browsing by Author "Hill, MR"
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- ItemA flexible copper based microporous metal-organic framework displaying selective adsorption of hydrogen over nitrogen(Royal Society of Chemistry, 2011-04-01) Nadeem, MA; Thornton, AW; Hill, MR; Stride, JAA microporous metal-organic framework [Cu-3(ipO)(2)(pyz)(2)](n), (ipO = 2-hydroxyisophthalic acid, pyz = pyrazine) was synthesized via an in situ. ligand transformation reaction. The microporous framework displays helical arrays of ipo ligands holding the Cu atoms in 2D sheets, whilst the coordination of pyz molecules acts to arrange these sheets into a microporous 3D structure. Remarkable selective sorption behaviour (>5) for H-2 over N-2 is observed and explained with molecular dynamics simulations.© 2011, Royal Society of Chemistry.
- ItemImproving hydrophobicity of MOFs using aliphatic linkers(Society of Crystallographers in Australia and New Zealand, 2017-12-03) Macreadie, LK; Brand, HEA; Hill, MRMetal-organic frameworks (MOFs) have become renowned throughout the chemistry and materials communities as an exciting suite of porous material, capable of being designed and adapted to suit various objectives and applications [1]. Aromatic ligands with carboxylate functionalities are a commonly selected organic linker when synthesising MOFs due to their commercial availability and the numerous variable coordination modes exhibited by these functionalities, consequently leading to a high degree of framework connectivity [2]. Structurally similar to 1,4-dicarboxybenzene, frequently used as an organic linker in MOF synthesis, is 1,4-dicarboxycubane due to its para coordination capabilities and carboxylate functionalities. Unlike 1,4-dicarboxybenzene, 1,4-dicarboxycubane is nonplanar in nature, features a higher steric bulk and is void of conjugation within the ring (Figure 1). These differing properties can be exploited to modify the local environment within the pores of resultant MOFs to be more hydrophobic. We have substituted 1,4-dicarboxybenzene with 1,4-dicarboxycubane during the synthesis of known and well-characterised MOFs with the aim of modifying the pore environment within the framework. These MOFs were structurally characterised using single crystal X-ray diffraction and Rietveld refinement of synchrotron X-ray diffraction data collected at the MX and PD beamlines at the Australian . Here we will discuss the structural and behavioural differences between the MOF species, pertaining to their selective gas sorption, water retention and thermal stability properties.
- ItemA low temperature reduction of CCl4 to solid and hollow carbon nanospheres using metallic sodium.(Elsevier, 2015-03-15) Choucair, M; Hill, MR; Stride, JACarbon nanospheres are obtained by reacting metallic sodium at 100 °C with tetrachloromethane under a flow of N2 gas at ambient pressure. The product consisted of both hollowed and solid carbon spheres, ranging between 20 and 300 nm in size and comprised of concentrically oriented, disordered graphitic fragments. The maximum surface area recorded for this nanostructured carbon is 830 m2 g−1. Morphological, structural, and chemical analysis of the product is carried out with HR-TEM, BET surface area, XPS, XRD, and Raman spectroscopy. The formation of the spherical shape of the carbon nanoparticles is discussed based on direct observations of the reaction at the interfacial phase boundary.Copyright © 2017 Elsevier B.V.
- 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.
- ItemSimple metal-catalyst-free production of carbon nanostructures(CSIRO Publishing, 2013-09-16) Ellis, TK; Paras, C; Hill, MR; Stride, JAWe report the metal-catalyst-free production of multiwalled carbon nanotubes and nanobubbles, in a chemical reduction of hexachlorobenzene by metallic sodium, giving high yields (in excess of 80 %) and at temperatures as low as 190°C for multiwalled carbon nanotubes and 100°C for nanobubble formation. The carbon nanotube samples produced under solvothermal conditions were found to consist of large bundles of nanotubes (>50 µm) consistent with a facial growth from the surface of the molten metal. Meanwhile, the nanobubbles produced under ambient pressure were found to be small (≤1 µm), polydispersed (smallest ~50 nm), and the bulk to have a large microporous area. With the regulatory complexities and high environmental and economic costs of remediating waste containing highly hazardous halogenated aromatic chemicals, necessitating high-temperature incineration under strictly controlled conditions, this low-temperature, low-cost chemical degradation of hexachlorobenzene is of great potential as a scalable and workable remediation technology. © 2013, CSIRO Publishing.
- ItemUltramicroporous MOF with high concentration of vacant Cu 11 sites(American Chemical Society, 2015-07) McCormick, LJ; Duyker, SG; Thornton, AW; Hawes, CS; Hill, MR; Peterson, VK; Batten, SR; Turner, DRAn ultramicroporous metal–organic framework (MOF) is reported that contains 0.35 nm nanotube-like channels with an unprecedented concentration of vacant CuII coordination sites. The nonintersecting, narrow channels in [Cu3(cdm)4] (cdm = C(CN)2(CONH2)−) align in two perpendicular directions, structurally resembling copper-doped carbon nanotubes with CuII embedded in the walls of the channels. The combination of ultramicroporosity with the exposed CuII coordination sites gives size-based selectivity of CO2 over CH4, based on pore-size distribution and modeling. Neutron powder diffraction and molecular dynamics simulations show the close packing of single rows of guests within the tubular nanostructure and interaction of CO2 with the exposed metal sites. © 2014, American Chemical Society.
- ItemA validated numerical model for residual stress predictions in an eight-pass-welded stainless steel plate(Trans Tech Publications, 2014-02-06) Patel, VI; Muránsky, O; Hamelin, CJ; Olson, MD; Hill, MR; Edwards, LWelding processes create a complex transient state of temperature that results in post-weld residual stresses. The current work presents a finite element (FE) analysis of the residual stress distribution in an eight-pass slot weld, conducted using a 316L austenitic stainless steel plate with 308L stainless steel filler metal. A thermal FE model is used to calibrate the transient thermal profile applied during the welding process. Time-resolved body heat flux data from this model is then used in a mechanical FE analysis to predict the resultant post-weld residual stress field. The mechanical analysis made use of the Lemaitre-Chaboche mixed isotropic-kinematic work-hardening model to accurately capture the constitutive response of the 316L weldment during the simulated multi-pass weld process, which results in an applied cyclic thermo-mechanical loading. The analysis is validated by contour method measurements performed on a representative weld specimen. Reasonable agreement between the predicted longitudinal residual stress field and contour measurement is observed, giving confidence in the results of measurements and FE weld model presented.