Mesoporous methyl-functionalized titanosilicate produced by aerosol process for the catalytic epoxidation of olefins

Lucia E. Manangon-Perugachi, Valentin Smeets, Alvise Vivian, Itika Kainthla, Pierre Eloy, Carmela Aprile, Damien P. Debecker, Eric M. Gaigneaux

Research output: Contribution to journalArticlepeer-review

Abstract

Titanosilicates (Ti-SiO2) are well-known catalysts for the epoxidation of olefins. Isolated Ti inserted in the silica framework in tetrahedral coordination are the active species. Recently, adjusting the hydrophobic/hydrophilic balance of such catalysts’ surfaces has appeared as a promising tool to further boost their performance. However, adjusting the hydrophobic/hydrophilic balance via a one-pot classical sol-gel generally leads to a decrease in the Ti dispersion and/or collapse of the pore network. To overcome this limitation, hydrophobic mesoporous Ti-SiO2 were here synthesized by aerosol-assisted one-pot sol–gel, which allowed the simultaneous control of their Ti loading, degree of methyl-functionalization, and textural properties. Methyl-functionalization was achieved by a partial substitution of tetraethoxy silane (TEOS) by methyltriethoxy silane (MTES) in different ratios. Solid-state29Si-NMR, FTIR, TGA, and vapor-phase water adsorption showed that methyl moieties were effectively incorporated, conferring a hydrophobic property to the Ti-SiO2 catalysts. ICP-AES, DRUV, XPS, and N2 physisorption demonstrated that Ti dispersion and textural properties were both successfully preserved upon the incorporation of the methyl moieties. In the epoxidation of cyclooctene with tert-butyl hydroperoxide as oxidant, the hydrophobic Ti-SiO2 showed higher catalytic performance than pristine Ti-SiO2 prepared without MTES. In addition to disentangling the positive effect of adjusting the hydrophobic/hydrophilic balance of epoxidation catalysts on their performance, this contribution highlights the advantages of the aerosol procedure to synthesize mesoporous functionalized catalysts with very high dispersion of active sites.

Original languageEnglish
Article number196
Pages (from-to)1-19
Number of pages19
JournalCatalysts
Volume11
Issue number2
DOIs
Publication statusPublished - Feb 2021

Keywords

  • Aerosol-assisted sol-gel
  • Mesoporous titanosilicate TiO-SiO
  • Olefin epoxidation
  • One-pot methyl-functional-ization
  • Surface hydrophobicity

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