Vanadium silicate xerogels in hydrogen peroxide catalyzed oxidations

Ronny Neumann, Michal Levin-Elad

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

Vanadium silicate xerogels (V2O5{single bond}SiO2) were prepared by the sol-gel method by hydrolysis of vanadium and silicon alkoxides. The use of these xerogels as catalysts for oxidation of alkenes, alcohols and phenol was studied using 30% aqueous hydrogen peroxide as oxidant. It was found that the manner of xerogel preparation strongly influenced the catalytic activity of V2O5{single bond}SiO2. Alcohols were the preferred solvents for the reaction and did not leach vanadium oxide into solution. For alkenes, epoxidation was the dominant oxidation reaction the yield and selectivity depending on the nucleophilicity and oxidizability of the substrate. For alkenes of intermediate nucleophilicity allylic oxidation was significant. Secondary alcohols were oxidized in low to fair yields whereas primary alcohols were inert. Phenol was oxidized selectively to a 2:1 mixture of hydroquinone/catechol. UV-vis and electron spin resonance spectra of V2O5{single bond}SiO2 treated with hydrogen peroxide conclusively showed formation of vanadium-peroxo species with polarization of the O{single bond}O bond as seen by formation of vanadium (IV) electron spin resonance spectra leading to oxidation by both heterolytic and homolytic cleavage.

Original languageEnglish
Pages (from-to)85-97
Number of pages13
JournalApplied Catalysis A: General
Volume122
Issue number2
DOIs
Publication statusPublished - Feb 16 1995

Fingerprint

Silicates
Vanadium
Xerogels
Hydrogen peroxide
Hydrogen Peroxide
Alkenes
Alcohols
Oxidation
Olefins
Phenol
Phenols
Paramagnetic resonance
Epoxidation
Silicon
Oxidants
Oxides
Sol-gel process
Hydrolysis
Catalyst activity
Polarization

Keywords

  • Alkene epoxidation
  • Catalyst preparation (sol-gel)
  • Phenol oxidation
  • Vanadium/silicate

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Cite this

Vanadium silicate xerogels in hydrogen peroxide catalyzed oxidations. / Neumann, Ronny; Levin-Elad, Michal.

In: Applied Catalysis A: General, Vol. 122, No. 2, 16.02.1995, p. 85-97.

Research output: Contribution to journalArticle

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