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  • 901.
    Öhman, L. O.
    et al.
    Umeå universitet.
    Ganemi, B.
    Kungliga tekniska högskolan, KTH.
    Björnbom, E.
    Kungliga tekniska högskolan, KTH.
    Rahkamaa, K.
    Åbo Akademi.
    Keiski, R. L.
    Uleåborg universitet.
    Paul, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Catalyst preparation through ion-exchange of zeolite Cu-, Ni-, Pd-, CuNi- and CuPd-ZSM-52002Inngår i: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 73, nr 2-3, s. 263-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ion-exchanged zeolite ZSM-5 is the best known catalyst for direct NOx decomposition and a viable candidate for NOx reduction with methane. The preparation is crucial for the efficiency of the conversion and this paper describes the ion-exchange, with Cu2+, Ni2+ or Pd2+, and the dual exchange, with Cu2+/Ni2+ or Cu2+/Pd2+, under appropriate pH and ion concentrations for maximum dispersion.

  • 902.
    Öhman, L.O.
    et al.
    Umeå universitet.
    Paul, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Materials aspects of titanium-doped aluminas: 14%Ti/γ-Al2O3/Cu and sulfided Al2O3-TiO2/NiMo2002Inngår i: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 73, nr 2-3, s. 242-251Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Materials aspects of titanium-doped alumina catalysts are discussed in light of a partly new synthesis route, ion exchange reactions and sulfidation. Starting with a solution of the isopropoxides of aluminum and titanium, we aimed at an Al:Ti ratio of 6:1, which corresponds to the maximum acidity of the final product. Transmission electron micrographs showed that the synthesis gave a product of nearly monodisperse, rectangular particles and X-ray diffractograms revealed an amorphous to nano-crystalline structure reminiscent of γ-Al2O3. The Brunauer-Emmet-Teller area was 340 m2 g-1 and the H+ titration found 3 acidic sites nm-2. These numbers indicate that the titanium modification may fourfold increase the ion exchange capacity of a regular alumina. The importance of titanium modification for catalysis is discussed in connection with selective catalytic reduction with hydrocarbon reactions over Cu/14%Ti-Al2O3 and hydrogenation of 1-Me-naphthalene over sulfided NiMo/Al2O3-TiO2. The Ti4+ ions in the alumina lattice are almost irreducible, but infrared spectra suggested that these ions act as dispersion agents not only for adsorbed Cu2+ ions, but also for a supported phase of sulfided NiMo. Finally, we show that a simple weight control can be used to monitor the sulfidation and to indicate if the synthesis has produced a separate, reducible titania phase.

  • 903.
    Öström, Jonatan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Bezrukov, Dmitry S.
    Department of Chemistry, M. V. Lomonosov Moscow State University.
    Nyman, Gunnar
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Gustafsson, Magnus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Erratum: “Reaction rate constant for radiative association of CF+” [J. Chem. Phys. 144, 044302 (2016)]2019Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, nr 24, artikkel-id 249901Artikkel i tidsskrift (Fagfellevurdert)
  • 904.
    Öström, Jonatan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Bezrukov, Dmitry S.
    Department of Chemistry, M. V. Lomonosov Moscow State University.
    Nyman, Gunnar
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Gustafsson, Magnus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Reaction rate constant for radiative association of CF+2016Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, nr 4, artikkel-id 44302Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reaction rate constants and cross sections are computed for the radiative association of carbon cations (C+) and fluorine atoms (F) in their ground states. We consider reactions through the electronic transition 11Π → X1Σ+ and rovibrational transitions on the X1Σ+ and a3Π potentials. Semiclassical and classical methods are used for the direct contribution and Breit–Wigner theory for the resonance contribution. Quantum mechanical perturbation theory is used for comparison. A modified formulation of the classical method applicable to permanent dipoles of unequally charged reactants is implemented. The total rate constant is fitted to the Arrhenius–Kooij formula in five temperature intervals with a relative difference of <3%. The fit parameters will be added to the online database KIDA. For a temperature of 10–250 K, the rate constant is about 10−21 cm3 s−1, rising toward 10−16 cm3 s−1 for a temperature of 30 000 K.

  • 905.
    Öztas, Ahmet M.
    et al.
    Hacettepe University, Ankara.
    Smith, Michael L.
    Anabolic Laboratories, Inc., Tempe, AZ.
    Paul, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Spacetime curvature is important for cosmology constrained with supernova emissions2008Inngår i: International journal of theoretical physics, ISSN 0020-7748, E-ISSN 1572-9575, Vol. 47, nr 9, s. 2464-2478Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate universe expansion models as functions of emission frequency ratio decline rather than redshift z, using the latest on-line, self-consistent data from 192 supernovae. We present results for simpler and some current models of cosmology, including those with dark energy (standard model) and a recent model correcting for the effect of a small time-dependent, emission frequency increase with lookback. This new model, with a gentle lookback decline of the Planck constant, and the standard model fit the data with similar confidence according to Bayesian Information Criteria. The standard model tends towards solutions high in matter density while remaining flat, but models without dark energy tend towards dilute universes with significant spacetime and curvature and a smaller Hubble constant. We conclude the normalized spacetime parameter, Ω k , should not be ignored and it includes the combined contributions of huge spacetime magnitude and curvature.

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