Electron spin resonance and optical spectroscopy of tubular aluminophosphate materials containing framework vanadium

Zhaohua Luan, Dongyuan Zhao, Larry Kevan

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13 Citations (Scopus)

Abstract

A series of aluminophosphate materials without (UHM-1) and with variable amounts of vanadium (VUHM-1) have been synthesized in the presence of a cationic surfactant cetyltrimethylammonium chloride and an organic base tetramethylammonium hydroxide. Powder X-ray diffraction and electron probe microanalysis show that both UHM-1 and VUHM-1 with V/A1 ratios up to 0.05 possess disordered arrays of tubular channels which mimic the hexagonal MCM-41 structure. The overall P/A1 ratio is about half of the initial unity ratio in the gel mixture, especially for VUHM-1. This indicates incomplete condensation of phosphorus oxide and a non-ideal aluminophosphate framework; this seems associated with poorer thermal stability than microporous aluminophosphate and mesoporous aluminosilicatc MCM-41. Electron spin resonance and diffuse reflectance ultraviolet-visible spectroscopies reveal that in as-synthesized VUHM-1 the vanadium exists as monoatomically dispersed square pyramidal VO2+ ions and as tetrahedral V5+ ions which are consistent with a framework location for the vanadium.

Original languageEnglish
Pages (from-to)93-99
Number of pages7
JournalMicroporous and Mesoporous Materials
Volume20
Issue number1-3
DOIs
Publication statusPublished - 1 Jan 1998
Externally publishedYes

Keywords

  • Electronic spin resonance
  • Mesoporous aluminophosphate
  • Molecular sieve
  • Vanadium

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