High loading TiO2 and ZrO2 nanocrystals ensembles inside the mesopores of SBA-15: Preparation, texture and stability

M. V. Landau, L. Vradman, Xueguang Wang, L. Titelman

Research output: Contribution to journalArticlepeer-review

90 Scopus citations

Abstract

TiO2 (30-80wt.%) and ZrO2 (48-75wt.%) were inserted inside the pores of SBA-15 mesostructured silica host by chemical solution decomposition (CSD) or internal hydrolysis (IH) of the corresponding alkoxides. Both methods yielded composites with 85-94% TiO2 crystallinity (anatase). In case of ZrO2, CSD yielded >95% crystallinity (tetragonal phase), while IH gave an amorphous ZrOx-phase that does not crystallize up to 1073 K. The guest Ti(Zr)-oxide phases did not block the SBA-15 pores, and their surface was fully accessible for nitrogen adsorption. Calcination in air of TiO2/SBA-15 and ZrO2/SBA-15 (CSD) composites up to 1073 K did not change the nanocrystals structure and slightly increased the domain size derived from XRD data from 5.0-8.5 to 6-10nm for TiO2 (IH and CSD) and from 4.5 to 6.5 nm for ZrO2 (CSD). After the same treatment the crystals domain size of bulk reference TiO 2 increased to >100nm with full conversion to rutile polymorph and of reference bulk ZrO2 - to 20-25 nm with partial conversion to monoclinic modification. Thorough characterization of the texture, structure, location and dispersion by HRTEM, SAXS, EDS, SEM, XRD, N2-adsorption methods allowed evaluation of the assembling mode of TiO2 and ZrO2 inside SBA-15 nanotubes: amorphous layer, ensemble of small 4-5 nm crystals (TiO2-IH and ZrO2-CSD) or single large 8.5nm crystals (TiO2-CSD).

Original languageEnglish
Pages (from-to)117-129
Number of pages13
JournalMicroporous and Mesoporous Materials
Volume78
Issue number2-3
DOIs
StatePublished - 1 Mar 2005

Keywords

  • Mesostructured silica
  • Nanocrystals
  • Stability
  • Titania
  • Zirconia

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