Performance of a novel low temperature NH3 remediation Catalyst

King Lun Yeung
Dept. of Chemical Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong, People Republic of China

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     Last modified: April 12, 2006

Abstract
Supported vanadium oxide catalysts have been known to be effective in selective catalytic reduction of nitrogen oxides (NOx) in the presence of ammonia (NH3) [1]. Titanium supported vanadium catalyst also displays activity for NH3 oxidation in temperature above 250 ºC [2, 3]. In this work, we investigate the performance of nanostructured V2O5/TiO2 for low temperature catalytic remediation of ammonia. This could have potential applications in odor removal technology and industrial flue gas treatment.

Nanostructured, anatase TiO2 (BET area of 300m2/g) was impregnated with ammonium metavanadate solution to produce catalysts containing less than one monolayer of V2O5.The catalysts were characterized by X-Ray photoelectron spectroscopy (XPS), temperature programmed reduction (TPR) and Raman spectroscopy.

The FT-Raman spectra of different vanadia loading samples indicated that isolated, monomeric V2O5 species (1030 cm-1) dominate on the surface. V2O5 crystals (990cm-1) were also present in catalyst with V2O5 loading in excess of a monolayer. The dispersed monomeric vanadia was observed to be more active for catalytic remediation of ammonia compared to V2O5 crystals.

Calcination and ozonification had been used to convert the vanadia precursor to its oxide form. Low temperature ozone treatment prevented unwanted sintering and maintained high catalyst dispersion. V2O5/TiO2 catalysts were tested for NH3 oxidation in a differential plug flow reactor. In each run, 25 mg of catalyst was reacted with 2185ppm NH3 in a synthetic air stream and we observe no by-product formation. It could be observed that ozone treatment could enhance catalytic performance almost by 2 fold in the 17wt% V2O5 catalyst.

References
[1] Michael D. Amiidis, Israel E. Wachs, Goutam Deo, Jih-Mirn Jehng and Du Soung Kim, Journal of Catalysis, 161, 247 (1996)
[2] F. Cavani and F. Trifiro, Catalysis Today, 4, 253 (1989)
[3] Yuejin Li and John N Armor, Applied Catalysis B, 13 131 (1997)