Recovery of homogeneous polyoxometallate catalysts from aqueous and organic media by a mesoporous ceramic membrane without loss of catalytic activity

S. Roy Chowdhury, Peter T. Witte, David H.A. Blank, Paul L. Alsters, Johan E. ten Elshof

Research output: Contribution to journalArticleAcademicpeer-review

14 Citations (Scopus)

Abstract

The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous γ-alumina membranes is reported. The recovery of Q12[WZn3(ZnW9O34)2] (Q=[MeN(n-C8H17)3]+) from toluene-based media was quantitative within experimental error, while up to 97 % of Na12[WZn3(ZnW9O34)2] could be recovered from water. The toluene-soluble POM catalyst was used repeatedly in the conversion of cyclooctene to cyclooctene oxide and separated from the product mixture after each reaction. The catalytic activity increased steadily with the number of times that the catalyst had been recycled, which was attributed to partial removal of the excess QCl that is known to have a negative influence on the catalytic activity. Differences in the permeability of the membrane for different liquid media can be attributed to viscosity differences and/or capillary condensation effects. The influence of membrane pore radius on permeability and recovery is discussed.
Original languageEnglish
Pages (from-to)3061-3066
Number of pages6
JournalChemistry: a European journal
Volume12
Issue number11
DOIs
Publication statusPublished - 2006

Keywords

  • IR-59188
  • Nanofiltration
  • Membranes
  • METIS-234949
  • Separation
  • homogeneous catalysis
  • Epoxidation

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