ScienceAsia 30 (2004): 341-349 |doi: 10.2306/scienceasia1513-1874.2004.30.341

A comparative study of toluene catalytic oxidation over cerium/TiO₂ (anatase) and vanadium/TiO₂ (anatase) catalysts

Attera Worayingyong,* Anwaraporn Niltharach and Yingyot Poo-arporn

 
ABSTRACT: Cerium and vanadium species supported on TiO₂ (anatase) were prepared by sol-gel formation, with the same contents of cerium (or vanadium) to titanium (in TiO₂), and calcined at 723 or 823 K. The Xray diffraction (XRD) patterns of the supported vanadium species showed mainly the anatase phase of TiO₂ , whereas the cerium species formed a less crystalline anatase phase. The X-ray photoemission spectroscopic (XPS) results proved V(V) and V(IV) in all vanadium samples; all cerium samples had a significant proportion of Ce(III). The catalytic activities of the cerium species were comparable to those of the well known vanadium species when the same mole ratio of the prepared catalysts was used in the catalytic oxidation of toluene. It is assumed that oxygen in the M-O-Ti bonds (M = Ce or V) together with the high oxidation states of Ce(IV) and V(V) play an important role in the oxygen transfer step of the oxidation reactions. The product selectivities from the high performance catalysts showed that the cerium/TiO₂ (anatase) was active for aromatic destruction, whereas the partially deactivated vanadium/TiO₂ (anatase) was suitable for partial oxidation of toluene, producing benzaldehyde as a major product.

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Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10903, Thailand.

* Corresponding author, E-mail: fsciarw@ku.ac.th

Received 28 Apr 2004, Accepted 27 Sep 2004