Vanadium Oxide on Titania

after thermal treatment at 748 K forl8 h in a flow of dry oxygen  

The catalysts prepared from V2O5 mixtures with anatase by UHIG, as reported by Sobalik et al., also exhibited strong interaction between a vanadium oxide overlayer and the anatase support. The resulting materials were structurally similar (if not identical) to catalysts that were conventionally prepared by impregnation methods. The catalytic activity of the UHIG catalysts in the SCR reaction was also comparable to that of conventional catalysts. A most remarkable result of the work of Sobalik et al. 

Haase et al. observed spreading of V2O5 on the anatase surface at 873 They also showed that the spreading was enhanced in an air atmosphere containing HCl gas, under which highly mobile oxychlorides are formed. Del Arco et al. reported the 

It should be noted that Vogt et al. and de Boer et al. recently reported on an alternative preparation route which consisted of deposition-precipitation of Mo from homogeneous solution onto Si02. The authors claim that this technique leads to highly dispersed catalysts. 

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Methylpyridines are easily converted into the corresponding nitriles. The ammoxidation of 3-methylpyridine to nicotinonitrile has been particularly extensively investigated, mainly because of the importance of the nitrile as precursor of vitamins. The catalysts used are mostly vanadium-containing oxides, e. g. vanadium-titanium oxide [86], vanadium-zirconium oxide [87], or multicomponent systems [30,88]. Yields of more than 90% at nearly complete conversion were recently reported (e. g. 100% selectivity for vanadium oxide on titania (anatase) catalysts with V2O5 loading < 3.4 mol% [89]. 

Process of selective catalytic reduction of nitrogen oxides by ammonia (SCR) involves injection of ammonia into a gas stream containing nitrogen oxides, then reduction of NOx by ammonia on the surface of a catalyst typically containing vanadium oxide on titania. The reactions involved are mildly exothermic (additional heat is required in most cases). Limits of the optimal process temperature, usually from 200 to 350°C, are dictated by catalyst activity at low temperatures and by the reaction selectivity at high temperatures. The NOj-containing gas flows often have low temperature and variable flow rates and concentrations. This combination of factors makes application of an RFR to NO reduction advantageous. One industrial unit for NO selective catalytic reduction was reported to operate in Russia [44], with ammonia water injection between two catalyst beds. 

Bond, G., Zurita, J. and Flamerz, S. (1986). Structure and Reactivity of Titania-supported Oxides. Part 2. Characterisation of Various Vanadium Oxide on Titania Catalysts by X-ray Photoelectron Spectroscopy, Appl Catal. B Environ., 27, pp. 353-362. 

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