Synthesis and catalytic properties of crystalline, microporous vanadium silicates with MEL structure

Journal Article · Tue Sep 01 00:00:00 EDT 1992 · Journal of Catalysis; (United States)

OSTI ID:6999059

Rao, P R.H.P.; Ramaswamy, A V; Ratnasamy, P ^[1]

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1. National Chemical Lab., Pune (India)

A thermally stable, vanadium-containing silicate with the MEL structure has been prepared by hydrothermal crystallization. XRD and framework IR spectra of samples with three different Si/V ratios suggest the presence of V ions in framework positions wherein the concentration of SiOH groups is likely to be high. ESR spectra of the as-synthesized and reduced samples indicate that vanadium (in the tetravalent state) is in an atomically dispersed state, but not in T{sub d} symmetry positions. Only V{sup 5+} ions were present on calcination, and the V{sup 4+} to V{sup 5+} transition was found to be reversible. The calcined samples contain exchangeable protons. These vanadium silicates are mildly acidic and the catalytically active in both acid-catalyzed (isomerization of m-xylene) as well as oxidation (phenol to hydroquinone and catechol) reactions. A plausible environment of vanadium at defect sites in the MEL lattice is suggested.

• OSTI ID: 6999059
• Journal Information: Journal of Catalysis; (United States), Vol. 137:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
PHENOLS
OXIDATION
VANADIUM SILICATES
CATALYTIC EFFECTS
CHEMICAL PREPARATION
XYLENES
ISOMERIZATION
ABSORPTION SPECTROSCOPY
CRYSTAL LATTICES
ELECTRON SPIN RESONANCE
INFRARED RADIATION
MICROSTRUCTURE
POROSITY
VALENCE
X-RAY DIFFRACTION
ALKYLATED AROMATICS
AROMATICS
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELECTROMAGNETIC RADIATION
HYDROCARBONS
HYDROXY COMPOUNDS
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
RADIATIONS
RESONANCE
SCATTERING
SILICATES
SILICON COMPOUNDS
SPECTROSCOPY
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing