Elucidation of Anchoring and Restructuring Steps during Synthesis of Silica-Supported Vanadium Oxide Catalysts

Alyssa M. Love, Carlos A. Carrero, Alessandro Chieregato, Joseph T. Grant, Sabrina Conrad, René Verel, Ive Hermans

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

We investigate the chemical reactions involved during the synthesis of supported vanadium oxide catalysts using chemical grafting of vanadium oxytriisopropoxide (VO(OiPr)3) to thermally pretreated silica under solvent-free conditions. VO(OiPr)3 is found to react with both site-isolated silanol (Si-OH) groups and strained siloxane (≡Si-O-Si≡) bridges at the silica surface. Solid-state 51V and 13C MAS NMR confirms the formation of two slightly different vanadium species associated with the two anchoring mechanisms. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), in situ Raman spectroscopy, and thermogravimetric analysis-differential scanning calorimetry-mass spectrometry (TGA-DSC-MS) were used to study the subsequent calcination, revealing the formation of a transient V - OH intermediate upon the release of propene, followed by the formation of isolated VO4 surface species upon elimination of water. X-ray absorption spectroscopy (XAS) and 51V MAS NMR of the calcined material confirm the conversion of the two original vanadium sites to a species with a single isotropic shift, confirming the formation of isolated, tetrahedral VO4 sites.

Original languageEnglish (US)
Pages (from-to)5495-5504
Number of pages10
JournalChemistry of Materials
Volume28
Issue number15
DOIs
StatePublished - Aug 9 2016

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.

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