Reactivity and physicochemical characterisation of V{sub 2}O{sub 5}-WO{sub 3}/TiO{sub 2} De-NO{sub x} catalysts
- Dipartimento di Chimica Industriale e Ingegneria Chimica G., Natta, Milan (Italy); and others
V{sub 2}O{sub 5}-WO{sub 3}/TiO{sub 2} samples with compositions similar to those of commercial de-NO{sub x} catalysts (WO{sub 3} {approximately} 9% w/w, V{sub 2}O{sub 5} < 3% w/w) are characterized by XRD, surface area and pore size distribution, Fourier transform infrared, laser Raman, UV-vis diffuse reflectance, electron paramagnetic resonance spectroscopies, and catalytic tests in the reduction of NO{sub x} by NH{sub 3}. The V{sub 2}O{sub 5}-WO{sub 3}/TiO{sub 2} catalysts exhibit higher reactivity than the binary V{sub 2}O{sub 5}/TiO{sub 2} and WO{sub 3}/TiO{sub 2} samples with the same metal loading, and the temperature window for the SCR reaction is greatly widened. The catalysts consist of antase TiO{sub 2} and their morphological properties closely resemble that of WO{sub 3}/TiO{sub 2} for (V + W) surface coverages lower than one. Monomeric vanadyls and wolframyls and polymeric W{sub w}O{sub y} groups are observed in the samples with low vanadia loadings that are apparently similar to those present on the surface of the binary oxide systems with comparable metal loadings. On increasing the vanadium loading, polyvanadate species are also formed. EPR, FTIR, FT-Raman, and UV-vis techniques indicate a strong electronic interaction between V and W oxide species at the surface of the TiO{sub 2} support. This interaction leads to a higher reducibility of the ternary sample with respect to the corresponding binary ones. A synergism between V and W oxide surface species is suggested, which accounts for the high reactivity of the ternary samples in the SCR reaction. It is suggested that the higher reducibility of the samples, due to the electronic interactions between V and W and the TiO{sub 2} support, is responsible for the higher reactivity of the ternary catalysts, particularly at low temperatures. 78 refs., 10 figs., 1 tab.
- OSTI ID:
- 111003
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 155; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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