Vanadium silica-supported

Chemical reduction. The injection of ammonia reduces NO emissions by the reduction of NO , to nitrogen and water. Although it can be used at higher temperatures without a catalyst, the most commonly used method injects the ammonia into the flue gas upstream of a catalyst bed (typically vanadium and/or tin on a silica support). 

Figure I. Oxygen uptake by supported clusters and vanadium oxide. Samples were pre-reduced and re-oxidized at the temperatures indicated on the abscissa. Silica-supported polyoxometalates PVl ( ), PV3 (A), PVI4 ( ). Bulk V2O5 (+, after [10])...

Catalytic activities of the silica-supported vanadium oxides in either 3% methanol or in 5% O2 and 3% ethanol. Oxygen uptake was measured at 625 K. O2 and 3%... 

SMPO [styrene monomer propylene oxide] A process for making propylene oxide by the catalytic epoxidation of propylene. The catalyst contains a compound of vanadium, tungsten, molybdenum, or titanium on a silica support. Developed by Shell and operated in The Netherlands since 1978. 

The newest and most commercially successful process involves vapor phase oxidation of propylene to AA followed by esterification to the acrylate of your choice. Chemical grade propylene (90—95% purity) is premixed with steam and oxygen and then reacted at 650—700°F and 60—70 psi over a molybdate-cobait or nickel metal oxide catalyst on a silica support to give acrolein (CH2=CH-CHO), an intermediate oxidation product on the way to AA. Other catalysts based on cobalt-molybdenum vanadium oxides are sometimes used for the acrolein oxidation step. 

Vanadium Oxides The stmcture of silica-supported vanadium oxides, which can catalyze the selective oxidation of NO and hydrocarbons [117, 118], has been assigned to tetrahedral oxovanadium(V) structures like [(=SiO)3VO], through inter alia Raman and NMR data [117], rather than to octahedraUy coordinated decavan-... 

Ethane Oxidation on Supported Vanadium Oxide. Figure 1 shows the rates of production of the major products of ethane oxidation over a series of silica-supported vanadium oxide catalysts. As was described earlier, the structure of the catalyst changed considerably with the active-phase loading (77). The low loading samples (0.3 -1.4%) were shown to consist primarily of 0=V03 monomeric units, while the high loading catalysts (3.5 - 9.8%) were composed of V2O5 crystallites. 

The reactivity of the supported vanadium oxide catalysts for other oxidation reactions also show similar trends as the oxide support is varied from titania to silica [13]. The activity and selectivity for partial oxidation products of vanadium oxide supported on titania being higher than vanadium oxide supported on silica. The oxidation activity of the supported vanadium oxide catalysts is related to the ability to donate oxygen to form the required oxidation products. The... 

Fricke et al. (107) have studied the formation of 02 and 0 on silica-supported V2Os-P205 catalysts. The 02 and O- formed are stabilized on vanadium ions, but the amount decreased with increasing fraction of P205. 

Hamilton N, Wolfram T, Tzolova Muller G, Havecker M, Krohnert J, Carrero C, Schomacker R, Trunschke A, Schlogl R. Topology of silica supported vanadium-titanium oxide catalysts for oxidative dehydrogenation of propane. Catalysis Science Technology. 2012 2(7) 1346—1359. 

FIGURE 11 TPR-Raman spectra of silica-supported vanadium oxide near monolayer coverage (0.8 V atoms/nm2) (source, M.A. Banares). 

Vanadium plays an important role in many industrial catalysts used extensively in a variety of applications including the production of SO3 from SO2, selective oxidation of hydrocarbons, reduction of nitrogen oxides with ammonia, and in the manufacture of many chemicals and chemical intermediates. Such catalysts typically consist of vanadium compounds supported on oxides such as silica, alumina, titania, etc., and their activity depends on factors such as the chemical form and crystalline environment... 

---