Catalytic Properties of V–Ti–O Catalysts in the Oxidation and Ammoxidation of o-xylene, Acenaphthene and β-picoline

<p>Catalytic properties of vanadium–titanium oxide catalysts in the oxidation and ammoxidation of o-xylene, acenaphthene and β-picoline have been studied. Methods of preparation of catalysts with varying amounts contents of V₂O₅ have been described. It has been shown that activity and selectivity in oxidation of organic compounds of different nature depends on the V2O5 content and the ratio of the oxides in the solid solution. Maximum selectivity in relation to phthalic and naphthalic anhydrides, naphthalimide and nitrile of nicotinic acid with the maximum conversion is observed with the catalysts having 4–6 wt.% of V₂O₅. Catalysts with other compositions showed lesser conversion of the initial substance. A catalyst, representing VO₂–TiO₂ solid solution, exhibits the least activity and selectivity among the tested samples for oxidation of o-xylene and ammoxidation of β-picoline. For oxidation and ammoxidation of acenaphthene, the least activity and selectivity are exhibited by a catalyst, containing alongside with the solid solution no more than 3% by weight of V₂O₅. Catalysts with an equal V₂O₅ amount, but differing one from the other by a composition of a solid solution, display different catalytic activity in o-xylene oxidation and β-picoline ammoxidation. Enrichment of solid solution with VO₂ or a decrease in the amount of the latter in the content decrease activity and selectivity of a catalyst.</p>

The DeNOx Characteristics of V/Ti Plate SCR Catalysts

A series of V2O5/WO3/TiO2plate catalysts were prepared via the incipient wetness impregnation method, with the V2O5content of 0.68 wt%, 1.01 wt%, 1.19 wt%, 1.5 wt% and the WO3loading of 4.8 wt%, 6.2 wt%, 7.9 wt%, 9.2 wt%, respectively. Selective catalytic reduction of nitric oxide by ammonia (NH3-SCR) experiments were performed to investigate the effects of the several factors on the performance of the catalysts, including the V2O5, WO3and MoO3content in the catalysts and the O2concentration in the flue gas. The results indicated that as the rising of the V2O5 content, the SCR activity of the V2O5/WO3/TiO2catalysts was firstly increased and then slightly decreased, with the best activity obtained at the V2O5content of 1.19 wt%. As the increasing of the WO3content, the activity was firstly increased slightly and then almost kept constant. Furthermore, the loading of the MoO3on the V2O5/WO3/TiO2plate catalysts would bring negative effects to the catalytic activity. In addition, the capability of the catalysts would slightly increase as the O2concentration rising up to 7%, and then became stable at higher O2concentrations.

The Characteristics of Ferroelectric Sr0.4Ba0.6Nb2-xVxO6 Dielectrics

In this study, it would be interesting to investigate ceramic material based on Sr0.4Ba0.6Nb2O6 composition, V2O5 was used to substitute Nb2O5 to form the compositions of Sr0.4Ba0.6Nb2-xVxO6, where 0 ≤ x ≤ 0.3. The prepared Sr0.4Ba0.6Nb2-xVxO6 ceramics were sintered from 1060oC to 1300oC, and the needed sintering temperatures were dependent on V2O5 content. The SEM micrographs showed that even 1220oC was used as the sintering temperature of Sr0.4Ba0.6Nb2O6 ceramics, the pores were still observed. The crystal intensities of some (h,k,l) planes, for example (3,2,0) and (5,5,0) planes, apparently increased with the increase of V2O5 content and slightly decreased with the increase of sintering temperatures. The temperature-dependent dielectric characteristics were measured from 25oC to 300oC at 1MHz as a function of sintering temperatures and V2O5 content. The studied results would show that the sintering temperatures and V2O5 content also had large influence on the maximum dielectric constants (revealed at Curie temperatures) and the temperature-dielectric curves of Sr0.4Ba0.6Nb2-xVxO6 ceramics.