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Publication - Dr Valeska Ting

    Mechanism of CO2 capture in nanostructured sodium amide encapsulated in porous silica

    Citation

    Tian, M, Lennox, M, Kruner, B, Rudic, S, Mays, TJ, Düren, T, Presser, V, Terry, L, Rolls, S, Fang, Y, Zhili, D & Ting, VP, 2018, ‘Mechanism of CO2 capture in nanostructured sodium amide encapsulated in porous silica’. Surface and Coatings Technology, vol 350., pp. 227-233

    Abstract

    In-situ inelastic neutron scattering (INS) studies of the densification of hydrogen (H2) confined in ultramicropores of different pore geometries at 77 K have provided, for the first time, information on the effects of pore geometry on H2 phase behaviour at pressures up to 10 MPa. Here we show via INS and high-pressure H2 adsorption measurement that slit-shaped pores with a pore diameter of ~0.7 nm cause increased physical constraint of the condensed H2 compared to cylindrical shaped pores, resulting in greater H2 densification. Molecular modelling indicates that the packing of H2 in carbon slit-pores is much more efficient than that in cylindrical pores, such as are found in carbon nanotubes, resulting in formation of a double-layer of immobilised H2 molecules in slit pores and pseudo-ordered packing in cylindrical pores of the same diameter. The average H2 densities in these slit pores and cylindrical pores are 70 and 50 m3g-1, respectively, calculated from the high pressure volumetric H2 isotherms at 77 K. This insight into the effects of pore geometry on confinement of molecules can be used to guide the development of new porous adsorbents tailored for maximum H2 storage capacities.

    Full details in the University publications repository