Study of MgO transformation into MgF2 in the presence of CF2Cl2

Aleksey A. Vedyagin, Alexander F. Bedilo, Ilya V. Mishakov, Ekaterina I. Shuvarakova

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6 Citations (Scopus)

Abstract

Alkaline-earth metal oxide aerogels prepared by sol-gel method followed by autoclave drying are nanocrystalline mesoporous materials with high reactivity. Bulk solid-state reaction of MgO aerogels with CF2Cl2 takes place after a long induction period, during which the active sites are accumulated on the surface of the nanoparticles. It was found that vanadium addition has a promoting effect on this reaction accelerating the process of the active sites formation. A method for characterization of electron-acceptor sites by electron spin resonance spectroscopy using perylene as the spin probe was developed. A good correlation was observed between the rate of the CF2Cl2 destructive sorption and the concentration of weak electron-acceptor sites. Simplified models of such sites were suggested. The acid sites on the modified MgO surface were supposed to be originated from separation of the charged fragments resulting in the surface polarization. Uncompensated oxygen substitution for chlorine and/or fluorine ions leads to appearance of Lewis acid sites while HCl/HF chemisorption results in Bronsted acid sites formation.

Original languageEnglish
Pages (from-to)523-538
Number of pages16
JournalJournal of the Serbian Chemical Society
Volume82
Issue number5
DOIs
Publication statusPublished - 2017

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Keywords

  • Acid sites
  • Aerogels
  • Destructive sorption
  • Freon-12
  • Spin probe
  • Vanadium

ASJC Scopus subject areas

  • Chemistry(all)

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