Catalyst for oxidation with hydrogen

B. Supported Mo Catalyst for Oxidation with Hydrogen Peroxide as the Oxidant... 

Solid catalysts may also be used for reactions implying oxidants differ by dioxygen. The most popular case is that of titanium-silicalite catalysts for oxidation with hydrogen peroxide. The active species in the presence of water has been characterised to be a side-on peroxo complex characterised by a Raman-detected 0-0 stretching at 618 cm Upon drying, this species converts into a hydroperoxo species characterised using IR by an 0-0 stretching at 837 cm and a broad OH band at 3400 cm ... 

Neumann R (2004) Polyoxometalates as catalysts for oxidation with hydrogen peroxide and molecular oxygen. In Beller M, Bolm C (eds) Transition metals for organic synthesis, 2nd edn., vol 2, WUey, Weinheim, p 415... 

The process was complicated by the formation of calcium manganite, CaMn206, known as Weldon mud. Invented by W. Weldon in 1866 and developed at St. Helens from 1868 to 1870. Operated in competition with the Deacon process until both were overtaken by the electrolytic process for making chlorine from brine. Weldon mud has been used as a catalyst for oxidizing the hydrogen sulfide in coal gas to elemental sulfur. 

Neumann, R. Mixed Addenda Phosphomolybdovanadates as Catalysts for Oxidations with Dioxygen and Hydrogen Peroxide. In Polyoxometalates from Platonic Solids to Anti-retroviral Activity Pope, M. T., Muller, A., Eds. Kluwer Academic Publishers Dordrecht, 1994 pp 307-313. 

M. C. A. van Vliet, 1. W. C. E. Arends, R. A. Sheldon, Tertiary arsine oxides Active and selective catalysts for epoxidation with hydrogen peroxide. Tetrahedron Lett. 40 (1999) 5239. 

P. T. Witte, P. L. Alsters, W. Jary, R. Milliner, P. Pochlauer, D. Sloboda-Rozner, R. Neumann, Self-assembled Nai2[WZn3(Zn Wg034)2] as an industrially attractive multi-purpose catalyst for oxidations with aqueous hydrogen peroxide, Org. Process Res. Dev. 8 (2004) 524. 

Up until the late seventies attempts to develop redox molecular sieves were mainly limited to the ion-exchange approach (see later). This situation changed dramatically with the discovery, by Enichem scientists in 1983 [6,7], of the unique activity of titanium silicalite-1 (TS-1) as a catalyst for oxidations with 30% aqueous hydrogen peroxide. Following the success of TS-1, interest in the development, and application in organic synthesis, of redox molecular sieves has increased exponentially and has been the subject of several recent reviews [8-11]. It has even provoked a revival of interest in another approach to producing redox molecular sieves the so-called ship-in-a-bottle method [12-15]. 

LARGE PORE TI-BETA ZEOLITE WITH VERY LOW ALUMINIUM CONTENT AN ACTIVE AND SELECTIVE CATALYST FOR OXIDATIONS USING HYDROGEN PEROXIDE... 

Witte, P., Alsters, P., Jary, W., et al. (2004). Self-Assemhled Nax2[WZn3(ZnW9034)2] as an Industrially Attractive Multi-Purpose Catalyst for Oxidations with Aqneons Hydrogen Peroxide, Org. Proc. Develop., 8, pp. 524—531. 

The use of molybdenum catalysts in combination with hydrogen peroxide is not so common. Nevertheless, there are a number of systems in which molybdates have been employed for the activation of hydrogen peroxide. A catalytic amount of sodium molybdate in combination with monodentate ligands (e.g., hexaalkyl phosphorus triamides or pyridine-N-oxides), and sulfuric acid allowed the epoxidation of simple linear or cyclic olefins [46]. The selectivity obtained by this method was quite low, and significant amounts of diol were formed, even though highly concentrated hydrogen peroxide (>70%) was employed. 

No hydride forms for very small particles. Yet when catalysts with such a small metal particle size are stored in air, they are converted to (crystalline) PdO. Reduction of this oxide with hydrogen produces Pd metal, not hydride. 

Listed in the Table 6.1 are some of the more common sources of oxygen employed for oxidations of organic compounds. Dioxygen is not listed because it requires a catalyst for oxidation at low temperatures. Likewise, hydrogen peroxide and ozone exhibit different activities when used with the proper heterogeneous catalyst. 

Titanium-containing zeolite was an efficient catalyst for oxidation of benzene with hydrogen peroxide in a microwave field, affording phenol with high selectivity. It was reported that microwaves had a strong effect on the selectivity of the reaction. 

DeDiox A process for destroying polychlorinated dioxins and furans in flue-gases by catalytic oxidation with hydrogen peroxide. The catalyst is based on silica and the process is operated at 80 to 100°C. Developed by Degussa from 1994. The business was offered for sale in 1998. 

Nearly all unsaturated compounds react rapidly with hydrogen at low temperatures and pressures in presence of finely divided metal catalysts such as nickel, platinum and palladium. For maximum catalytic effect, the metal is taken in the finely divided state. This is achieved for platinum and palladium by reducing the metal oxide with hydrogen. A specially active form of nickel is the Raney nickel . 

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