Oxidation over vanadia-titania

Dumesic, J.A., Topspe, N.Y., Slabiak, T., Morsing, P., Clausen, B.S., Tornqvist, E., and Topsoe, H. Microkinetic analysis of the selective catalytic reduction (SCR) of nitric oxide over vanadia/titania-based catalysts. Stud. Surf. Sci. Catal 1993, 75, 1325-1337. 

Other metal oxide catalysts studied for the SCR-NH3 reaction include iron, copper, chromium and manganese oxides supported on various oxides, introduced into zeolite cavities or added to pillared-type clays. Copper catalysts and copper-nickel catalysts, in particular, show some advantages when NO—N02 mixtures are present in the feed and S02 is absent [31b], such as in the case of nitric acid plant tail emissions. The mechanism of NO reduction over copper- and manganese-based catalysts is different from that over vanadia—titania based catalysts. Scheme 1.1 reports the proposed mechanism of SCR-NH3 over Cu-alumina catalysts [31b],... 

Catalyst A process for treating industrial off-gases by catalytic oxidation over a titania/vanadia catalyst. Offered by BASF. 

Selective and Nonselective Pathways in Oxidation and Ammoxidation of Methyl-Aromatic Compounds over Vanadia—Titania... 

The gas-phase selective oxidation of o-xylene to phthalic anhydride is performed industrially over vanadia-titania-based catalysts ("7-5). The process operates in the temperature range 620-670 K with 60-70 g/Nm of xylene in air and 0.15 to 0.6 sec. contact times. It allows near 80 % yield in phthalic anhydride. The main by-products are maleic anhydride, that is recovered with yields near 4 %, and carbon oxides. Minor by-products are o-tolualdehyde, o-toluic acid, phthalide, benzoic acid, toluene, benzene, citraconic anhydride. The kinetics and the mechanism of this reaction have been theobjectof a number of studies ( 2-7). Reaction schemes have been proposed for the selective pathways, but much less is known about by-product formation. 

The comparison of the bands observed after benzonitrile and benzylamine transformation over vanadia-titania allows us to suggest that benzamide can also be obtained by oxidation of benzylamine. Moreover, the growth of the absorption near 1640 cm and the appearance of bands at 1330 and 1240 cm during benzylamine oxidation suggests that benzaldehyde is also formed. A likely assignment for the band at 1670 cm is to the stretching of a C=N double bond (75), so being likely indicative of the formation of benzaldimine. 

C U I Odenbrand, A Bahamonde, P Avila, J Blanco, Kinetic study of the selective reduction of nitnc oxide over vanadia-tungsta-titania/sepiolite catalyst, Appl. Catal., B Environ. 5 117 (1994). 

Dumesic JA, Tops0e N-Y, Tops0e H, Chen Y, Slabiak T (1996) Kinetics of Selective Catalytic Reduction of Nitric Oxide by Ammonia over Vanadia/Titania. J Catal 163... 

Lomnicki S, Lichtenberger J, Xu Z, Waters M, Kosman J, Amiridis MD. Catalytic Oxidation of 2,4,6-Trichlorophenol over Vanadia/Titania-based Catalysts. Appl Catal B Environ 2003 46 105-119. 

Busca, G. (1993). Infrared characterization of the hydrocarbon species intermediates in the oxidation of toluene and xylenes over vanadia-titania catalysts, J. Chem. Soc. Faraday Trans. I, 89, pp. 753-755. 

Busca, G. (1993). Selective and non-selective pathways in the oxidation and ammoxidation of methyl-aromatics over vanadia-titania catalysts FTIR studies, in S. Oyama and J. Hightower (eds.), Catalytic Selective Oxidation, American Chemical Society, Washington, DC,... 

Dumesic, J.A., Topspe, H., Chen, Y., and Slabiak, T. Kinetics of selective catalytic reduction of nitric oxide by ammonia over vanadia/titania. J. Catal 1996, 163, 409-417. 

The reactivity ot the titania supported vanadium oxide catalysts was probed by the methanol oxidation reaction. The oxidation ot methanol over the titania supported vanadia catalysts exclusively yielded tormaldehyde, 95%+, as the reaction product. The titania support in the absence ot surtace vanadia yielded dimethyl ether and trace amounts ot CO2 The almost... 

The reaction rate of the reaction of NH3, NO and O2 over vanadia on titania catalysts at 365 K was 1.9x10 (molg s ) and the activation energy 37kJmol [48]. These data were obtained by using NO, a positron emitter, at very low concentrations (5 x 10 ppm). Moreover, it was confirmed that the nitrogen atom of ammonia combines with the nitrogen atom of nitric oxide. 

Hagenmaier and Mittelbach [150] used a vanadia on titania catalyst at 523 K. The activity decreased by 30% after 6000 h on stream. The catalyst was contaminated with Hg, Pb, Cd, As, and sulfates. Additionally, it was found that dioxines and furanes were oxidized over the catalyst (Section 1.2.5). 

Supported vanadia, used to promote the selective oxidation of hydrocarbons. Is another example. Vanadia, with or without promoters, may be supported on silica (naphthalene oxidation [38]), on titania o-xylene oxidation [39]) or on a-alumina (benzene oxidation [ AO]). It was believed that supports should have open porosity (and associated lower surface area) in order to minimise over oxidation to carbon oxides. However, it was shown that reasonably high activities and selectivities could be obtained over vanadia supported on high surface area material and it was suggested that low selectivity was, in fact, primarily associated with high acidity on the support [Al]. In agreement with this, vanadia supported on 7-alumina showed zero selectivity for the production of maleic anhydride from benzene If this is the case, then a high surface area support with minimal acidity would be desired,... 

Idakieva, V, Ilieva, L., Andreeva, D., et al. (2003). Complete Benzene Oxidation over Gold-vanadia Catalysts Supported on Nanostructured Mesoporous Titania and Zirconia, App/. Catal. A.- Gen., 243, pp. 25-39. 

The reaction is carried out either over bulk Fe2(Mo04)3-Mo03 or over silver catalysts with very high selectivity. Over different catalysts other selective oxidation products or total oxidation can be obtained. Some years ago we focused our attention on vanadia-titania catalysts, where methyl formate can be obtained with high yields. ... 

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