Aluminium molybdate

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Aluminium molybdate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.035.607 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
  • InChI=1S/2Al.3Mo.12O/q2*+3;;;;;;;;;;6*-1 Yes check.svgY
    Key: NKSYNYABFPVRNP-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/2Al.3Mo.12O/q2*+3;;;;;;;;;;6*-1
    Key: NKSYNYABFPVRNP-WODKIKDAAY
  • [Al+3].[Al+3].[O-][Mo](=O)(=O)[O-].[O-][Mo]([O-])(=O)=O.[O-][Mo]([O-])(=O)=O
Properties
Al2(MoO4)3
Molar mass 533.77 g mol−1
Appearancegrey, metallic solid/powder
odorless
Melting point 705 °C (1,301 °F; 978 K)
slightly soluble in water
Structure [1]
P21/a, No. 14
a = 15.3803(9) Å, b = 9.0443(1) Å, c = 17.888(1) Å
α = 90°, β = 125.382(3)°, γ = 90°
Hazards
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability (red): no hazard codeInstability (yellow): no hazard codeSpecial hazards (white): no code
1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Aluminium molybdate is the chemical compound Al2(MoO4)3. It forms in certain hydrodesulfurization catalysts when alumina is doped with excess molybdenum. [2] When molybdates are used to inhibit corrosion in aluminum piping, the protective film formed is hydrated aluminum molybdate. [3] [4] Although small quantities of aluminum molybdate form during aluminothermic reduction of molybdia, mechanical activation inhibits their formation. [5]

Large-scale samples can be prepared via sol-gel synthesis, [6] and have been proposed for molybdenum-99 storage in nuclear medicine. [7]

The room temperature crystal structure was refined using time-of-flight powder neutron diffraction data. It is monoclinic and isostructural with Fe2(MoO4)3 and Cr2(MoO4)3. [1] At high temperatures, the crystal rearranges to β‑Al2(MoO4)3, isostructural with scandium tungstate. [8]

Aluminum molybdate has a very low thermal expansion coefficient near room temperature.

References

  1. 1 2 Harrison, W. T. A.; Cheetham, A. K.; Faber, J. (1988). "The crystal structure of aluminium molybdate". Journal of Solid State Chemistry. 76 (2): 328–333. Bibcode:1988JSSCh..76..328H. doi:10.1016/0022-4596(88)90226-5.
  2. ↑ Medema, J.; van Stam, C.; de Beer, V. H. J.; Konings, A. J. A.; Koningsberger, D. C. (2 May 1977). "Raman spectroscopic study of Co–Mo/γ-Al2O3 catalysts" (PDF). Journal of Catalysis. 53 (published 1978): 386–400. doi:10.1016/0021-9517(78)90110-0 – via Eindhoven University of Technology library.
  3. ↑ McCune, R. C.; Shilts, R. L.; Ferguson, S. M. (1982-01-01). "A study of film formation on aluminum in aqueous solutions using Rutherford backscattering spectroscopy" . Corrosion Science. 22 (11): 1049–1065. doi:10.1016/0010-938X(82)90091-9. ISSN   0010-938X.
  4. ↑ Byrne, Christian E.; Quesada Cangahuala, Nereida V.; D'Alessandro, Oriana; Deyá, Cecilia (2023-07-10). "Cerium and aluminum molybdates as inhibitors of the aluminum AA1050 corrosion process in aqueous NaCl solutions" . Materials and Corrosion. 75: 73–83. doi:10.1002/maco.202313940. ISSN   0947-5117. S2CID   259872397.
  5. ↑ Sheybani, K.; Paydar, M. H.; Shariat, M. H. (2019-08-01). "Effect of mechanical activation on aluminothermic reduction of molybdenum trioxide" . International Journal of Refractory Metals and Hard Materials. 82: 245–254. doi:10.1016/j.ijrmhm.2019.04.015. ISSN   0263-4368. S2CID   149603638.
  6. ↑ Ari, Monica; Miller, Kimberly J.; Marinkovic, Bojan A.; Jardim, Paula M.; de Avillez, Roberto; Rizzo, Fernando; White, Mary Anne (19 October 2010) [19 November 2010]. "Rapid synthesis of the low thermal expansion phase of Al2Mo3O12 via a sol–gel method using polyvinyl alcohol". Journal of Sol-Gel Science and Technology. 58. Springer (published 2011): 121–125. doi:10.1007/s10971-010-2364-9. S2CID   97549526.
  7. ↑ Amin, M.; El-Amir, M. A.; Ramadan, H. E.; El-Said, H. (2018-11-01). "99Mo/99mTc generators based on aluminum molybdate gel matrix prepared by nano method" . Journal of Radioanalytical and Nuclear Chemistry. 318 (2): 915–922. doi:10.1007/s10967-018-6141-5. ISSN   1588-2780. S2CID   106317533.
  8. ↑ Harrison, William T. A. (1995-11-01). "Crystal structures of paraelastic aluminum molybdate and ferric molybdate, β-Al2(MoO4)3 and β-Fe2(MoO4)3" . Materials Research Bulletin. 30 (11): 1325–1331. doi:10.1016/0025-5408(95)00157-3. ISSN   0025-5408.
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