2018-Sustainable Industrial Processing Summit
SIPS2018 Volume 3. Fehrmann Intl. Symp. / Molten Salt and Ionic Liquid

Editors:F. Kongoli, M. Haumann, P. Wasserscheid, T. Welton, M. Gaune-Escard, A. Angell, A. Riisager
Publisher:Flogen Star OUTREACH
Publication Year:2018
Pages:154 pages
ISBN:978-1-987820-86-7
ISSN:2291-1227 (Metals and Materials Processing in a Clean Environment Series)
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    Molten Re(VII)-Oxosulfato Complexes in the Re2O7-K2S2O7 System Studied by Raman Spectroscopy at 260-470°C

    Chrysanthi Andriopoulou1; Ioannis Anastasiou2; Soghomon Bogosian2;
    1FORTH-ICE/HT AND UNIVERSITY OF PATRAS, Patras, Greece; 2UNIVERSITY OF PATRAS, Patras, Greece;
    Type of Paper: Regular
    Id Paper: 67
    Topic: 13

    Abstract:

    Dissolution reactions of transition metal oxides (e.g. V<sub>2</sub>O<sub>5</sub>, Nb<sub>2</sub>O<sub>5</sub>, MoO<sub>3</sub>, WO<sub>3</sub>) in molten pyrosulfate, and formation of the corresponding molten metal oxosulfato complexes [1-4] have expanded our knowledge on coordination chemistry of the pertinent transition metals, and provided a very useful family of coordination complexes as reference compounds for understanding the molecular structure of supported metal oxides, commonly used as catalysts [5]. Herein, we show that the oxide of a heptavalent transition metal, Re<sub>2</sub>O<sub>7</sub> (m.p. 297°C), undergoes likewise a reaction-induced dissolution in molten potassium pyrosulfate. Large amounts of Re<sub>2</sub>O<sub>7</sub> can be dissolved in molten K<sub>2</sub>S<sub>2</sub>O<sub>7</sub> (i.e. a mixture with X(Re<sub>2</sub>O<sub>7</sub>) = 0.5 fuses readily at 260°C). The structural and vibrational properties of molten Re(VII)I oxosulfato complexes formed in binary Re<sub>2</sub>O<sub>7</sub>-K<sub>2</sub>S<sub>2</sub>O<sub>7</sub> (as well as ternary Re<sub>2</sub>O<sub>7</sub>-K<sub>2</sub>S<sub>2</sub>O<sub>7</sub>-K<sub>2</sub>SO<sub>4</sub>) molten mixtures under O<sub>2</sub> atmosphere and static equilibrium conditions are studied by Raman spectroscopy at temperatures of 260-470°C. The corresponding composition effects are explored in the X(Re<sub>2</sub>O<sub>7</sub>) = 0 - 1 range. A quantitative exploitation of the relative Raman band intensities, due to the species present at static equilibrium, allows to determine the stoichiometry of the reaction taking place in the binary system [Re<sub>2</sub>O<sub>7</sub> + nS<sub>2</sub>O<sub>7</sub>(2-) = C(2n-)] pointing to n = 1. Temperature and composition dependent evolutions of molecular structures and configurations are discussed and consistent band assignments are proposed.

    Keywords:

    Characterization; Ion; Mixtures; Moltensalt; Oxides;

    References:

    [1] S. Boghosian, A. Chrissanthopoulos, R. Fehrmann, J. Phys. Chem. B 106 (2002) 49-56.<br />[2] A. L. Paulsen, F. Borup, R. W. Berg, S. Boghosian, J. Phys. Chem. A 114 (2010) 7485-7493.<br />[3] A. L. Paulsen, A. G. Kalampounias, R. W. Berg, S. Boghosian, J. Phys. Chem. A 115 (2011) 4214-4222.<br />[4] A. G. Kalampounias, G. Tsilomelekis, R. W. Berg, S. Boghosian, J. Phys. Chem. A 116 (2012) 8861-8872.<br />[5](a) S. Boghosian, R. Fehrmann in "Molten Salt Chemistry - From Lab to Applications", F. Lantelme & H. Groult Eds., Elsevier (2013) 131-158; (b) G. Tsilomelekis, S. Boghosian, Catal. Sci. Technol. 3 (2013) 1869-1888.

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    Cite this article as:

    Andriopoulou C, Anastasiou I, Bogosian S. (2018). Molten Re(VII)-Oxosulfato Complexes in the Re2O7-K2S2O7 System Studied by Raman Spectroscopy at 260-470°C. In F. Kongoli, M. Haumann, P. Wasserscheid, T. Welton, M. Gaune-Escard, A. Angell, A. Riisager (Eds.), Sustainable Industrial Processing Summit SIPS2018 Volume 3. Fehrmann Intl. Symp. / Molten Salt and Ionic Liquid (pp. 139-144). Montreal, Canada: FLOGEN Star Outreach