Selective oxidation studies

G.I. Golodets, in G. Centi and F. Trifird, New Developments in Selective Oxidation, Studies in Surface Science and Catalysis, Vol. 55, Elsevier, Amsterdam, 1990, p. 693. 

M.J. Bartoli, L. Monceaux, E. Bordes, G. Hecquet and P. Courtine, in "New Developments in Selective Oxidation, Studies in Surface Science and Catal., vol 72", P. Ruiz and B. Delmon (Eds.), Elsevier Science, Amsterdam, 1992, 81. 

Mamedov, A., Shiryaev, R, Shashkin, D., et al. (1990). Selective dehydrogenation of ethane by carbon dioxide over Fe-Mn oxide catalyst An in situ study of catalyst phase-composition and structure, in G. Centi and F. Trifiro (eds). Neve Developments in Selective Oxidation(Studies in Surface Science and Catalysis, 55), Elsevier, Amsterdam, pp. 477-482. 

Epoxyfarnesol was first prepared by van Tamelen, Stomi, Hessler, and Schwartz 4 using essentially this procedure. It is based on the findings of van Tamelen and Curphey5 that N-bromosuccinimide in a polar solvent was a considerably more selective oxidant than others they tried. This method has been applied to produce terminally epoxidized mono-, sesqui-, di-, and triterpene systems for biosynthetic studies and bioorganic synthesis.6 It has also been applied successfully in a simple synthesis of tritium-labeled squalene [2,6,10,14,18,22-Tetracosahexaene, 2,6,10,15,19,23-hexamethyl-, (all-E)-] and squalene-2,3-oxide [Oxirane, 2,2-dimethyl-3-(3,7,12,16,20-pentamethyl-3,7,ll,-15,19-heneicosapentaenyl)-, (all-E)-],7 and in the synthesis of Cecropia juvenile hormone.8... 

R.B. Grant, and R.M. Lambert, A single crystal study of the silver-catalyzed selective oxidation and total oxidation of ethylene, 7. Catal. 92, 364-375 (1985). 

Selective oxidation of p-xylene to terephthaldehyde (TPAL) on W-Sb oxide catalysts was studied. While WO3 was active in p-xylene conversion but non-selective for TPAL formation, addition of Sb decreased the activity in p-xylene conversion but increased TPAL selectivity significantly. Structure change was also induced by Sb addition. Evidences from various characterization techniques and theoretical calculation suggest that Sb may exist as various forms, which have different p-xylene adsorption property, reactivity toward p-xylene and TPAL selectivity. Relative population of each species depends on Sb content. 

Our study was focused on the influence of reducing power on the selective oxidation of H2S over the various transition metal oxides, which would be proceeded by the redox mechanism [5,6]. The redox mechanism and the reducing power [7] in selective oxidation of H2S can be defined as follows ... 

In the present study, we report the synthesis, characterisation and catalytic properties (in selective oxidation reactions) of copper acetate, copper tetradecachlorophthalocyanine and copper tetranitrophthalocyanine encapsulated in molecular sieves Na-X, Na-Y, MCM-22 and VPI-5. Both molecular oxygen and aqueous HjOj have been used as the oxidants. The... 

After the reaction for 5 h in a reactant stream of CH , O, and Hj (P(CHJ= 33.7, P(0,)= 8.4 and P(H2)= 50.7 kPa), the catalyst was analyzed by XRD, Mossbauer and XPS studies. As regarding the XRD and Mossbauer spectroscopic measurements, obvious changes were not observed before and after the reaction. On the other hand, a marked change was observed in the XPS spectrum of the catalyst after the reaction. As shown in Fig. 2, besides the peak at 57.7 eV, which was the only peak of Fe3p obtained for the sample before the reaction and was ascribed to Fe(III), a clear shoulder at 56.1 eV was observed after the reaction. This can be ascribed to the Fe(ll) on the catalyst surface. The same phenomenon has been reported for FeP04 catalyst [13]. Such observations suggest the occurrence of the redox of iron between Fe(Iil) and Fe(II) during the reaction. We believe that this redox plays a key role in the formation of a new active center and thus is important in the selective oxidation of CH4... 

The method outUned above was initially investigated for the introduction of isolated Ti(IV) sites onto a sihca substrate for use in selective oxidation catalysis. Since the development of a silica-supported Ti(lV) epoxida-tion catalyst by Shell in the 1970s, titania-sihca materials have attracted considerable attention [135,136]. Many other titania-sihca materials have been studied in this context including, but not hmited to, TSl and TS2 (titanium-substituted molecular sieves), Ti-/i (titanium-substituted zeolite). 

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