Vanadium complexes tungsten-based catalysts

MAO as activator. Generally, the turnover rates for these systems are only moderate, with that for 33 being on the high side at 470 g(PE)/mmol(Ta)/h/atm. Activities for 34 and the vanadium complex CpV(A -p-tolyl)Cl2 were 0.2 and 8.3 g(PE)/mmol(M)/h/atm, respectively (106). Molybdenum- and tungsten-based systems are similarly mediocre catalysts (106). 

Early catalysts for acrolein synthesis were based on cuprous oxide and other heavy metal oxides deposited on inert siHca or alumina supports (39). Later, catalysts more selective for the oxidation of propylene to acrolein and acrolein to acryHc acid were prepared from bismuth, cobalt, kon, nickel, tin salts, and molybdic, molybdic phosphoric, and molybdic siHcic acids. Preferred second-stage catalysts generally are complex oxides containing molybdenum and vanadium. Other components, such as tungsten, copper, tellurium, and arsenic oxides, have been incorporated to increase low temperature activity and productivity (39,45,46). 

Dehydrogenation to methyl methacrylate of the isobotyrate produced by the carbonyiation of propylene in the presence of methanol and a complex of rhodium, cobalt or palladium. The isobutyrate is converted with catalysts based on molybdenum, tungsten, vanadium, phosphomoiybdic acids and possibly heteropolyacids. It has been developed chiefly by Asahi, BASF, Eastman, Mitsubishi, Mobil, foray, etc. 

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