Monolayer V2O5/TiO2-ZrO2 catalysts for selective oxidation of o-xylene: preparation and characterization
- Monolayer V2O5/TiO2-ZrO2 catalysts for selective oxidation of o-xylene: preparation and characterization
- Komateedi Narayana Rao; Perala Venkataswamy; Pankaj Bharali; 하헌필; Benjaram M. Reddy
- Selective oxidation; V2O5 dispersion; thermal stability; conversion; TiO2-ZrO2; Redox properties; o-Xylene; Phthalic anhydride
- Issue Date
- Research on chemical intermediates
- VOL 38, NO 3-5, 733-744
- A series of TiO2–ZrO2 supported V2O5 catalysts with vanadia loadings
ranging from 4 to 12 wt% were synthesized by a wet impregnation technique and
subjected to various thermal treatments at temperatures ranging from 773 to
1,073 K to understand the dispersion and thermal stability of the catalysts. The
prepared catalysts were characterized by X-ray powder diffraction (XRD), BET
surface area, oxygen uptake, and X-ray photoelectron spectroscopy (XPS) techniques.
XRD results of 773 K calcined samples conferred an amorphous nature of
the mixed oxide support and a highly dispersed form of vanadium oxide. Oxygen
uptake measurements supported the formation of a monolayer of vanadium oxide
over the thermally stable TiO2–ZrO2 support. The O 1s, Ti 2p, Zr 3d, and V 2p core
level photoelectron peaks of TiO2–ZrO2 and V2O5/TiO2–ZrO2 catalysts are sensitive
to the calcination temperature. No significant changes in the oxidation states of
Ti4? and Zr4? were noted with increasing thermal treatments. Vanadium oxide
stabilized as V4? at lower temperatures, and the presence of V5? is observed at
1,073 K. The synthesized catalysts were evaluated for selective oxidation of
o-xylene under normal atmospheric pressure in the temperature range of
600–708 K. The TiO2–ZrO2 support exhibits very less conversion of o-xylene,
while 12 wt% V2O5 loaded sample exhibited a good conversion and a high product
selectivity towards the desired product, phthalic anhydride.
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