A comparative investigation on the properties of Cr-SBA-15 and CrOx/SBA-15

Lei Zhang, Yanhui Zhao, Hongxing Dai*, Hong He, Chak Tong AU

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

99 Citations (Scopus)

Abstract

High-surface area and well-ordered mesoporous Cr-incorporated SBA-15 (Cr-SBA-15) and SBA-15-supported chromia (CrOx/SBA-15) with Cr surface density = 0.05-1.11 Cr-atom/nm2 have been prepared, respectively, using the one-step synthesis and incipient wetness impregnation method, and characterized by AAS, XRD, BET, ESEM, TEM, XPS, laser Raman, UV-Vis, FT-IR, and H2-TPR. It is observed that the Cr-SBA-15 and CrOx/SBA-15 samples showed an evolution of surface morphology from long chain-shaped to short rod-like and further to an irregularly spherical architecture at elevated Cr content, which might arise from the interaction of Cr ions or CrOx domains with SBA-15. There were co-presence of tetrahedrally coordinated mono- and poly-chromate (Cr6+) as well as octahedrally coordinated Cr3+ species in Cr-SBA-15 and CrOx/SBA-15, with the Cr6+ species being dominant at Cr surface density ≤0.22 Cr-atom/nm2 in Cr-SBA-15 and Cr ≤0.54 Cr-atom/nm2 in CrOx/SBA-15, whereas the amount of the Cr3+ species increased markedly at Cr surface density ≥0.53 Cr-atom/nm2 due to the formation of crystal Cr2O3 phase. Maximal Cr incorporation into Cr-SBA-15 and one monolayer surface CrOx coverage on CrOx/SBA-15 occurred at Cr surface density ≤0.53 Cr-atom/nm2 and <1.11 Cr-atom/nm2, respectively. The CrOx/SBA-15 samples exhibited better reducibility than the Cr-SBA-15 samples, with the best reducibility exhibited at Cr surface densities of 0.54 and 0.12 Cr-atom/nm2, respectively.

Original languageEnglish
Pages (from-to)42-54
Number of pages13
JournalCatalysis Today
Volume131
Issue number1-4
DOIs
Publication statusPublished - 29 Feb 2008

Scopus Subject Areas

  • Catalysis
  • Chemistry(all)

User-Defined Keywords

  • Chromium-incorporated SBA-15
  • Mesoporous silica SBA-15
  • Reducibility
  • SBA-15-supported chromia
  • Surface chromia species
  • Surface morphology

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