Cobalt-manganese oxide-copper catalyst

With a catalyst of cobalt-manganese oxide-copper small yields of higher hydrocarbons have been obtained together with oxygenated products.100 The synthesis of identifiable quantities of olefin hydrocarbons were reported in 1927.110... 

Under the conditions where the chain oxidation process occurs, this reaction results in chain termination. In the presence of ROOH with which the ions react to form radicals, this reaction is disguised. However, in the systems where hydroperoxide is absent and the initiating function of the catalyst is not manifested, the latter has a retarding effect on the process. It was often observed that the introduction of cobalt, manganese, or copper salts into the initial hydrocarbon did not accelerate the process but on the contrary, resulted in the induction period and elongated it [4-6]. The induction period is caused by chain termination in the reaction of R02 with Mn"+, and cessation of retardation is due to the formation of ROOH, which interacts with the catalyst and thus transforms it from the inhibitor into the component of the initiating system. 

Hutchings, G.J., Copperthwaite, R.G., Gottschalk, F.M., Hunter, R., Mellor, J., Orchard, S.W., and Sangiorgio, T. A comparative evaluation of cobalt chromium oxide, cobalt manganese oxide, and copper manganese oxide as catalysts for the water-gas shift reaction. Journal of Catalysis, 1992, 137, 408. 

Ions of transition metals (homogeneously or in some cases supported on polymers [5]) also effectively catalyze the autoxidation. Salts of cobalt, manganese, iron, copper, chromium, lead, and nickel are used as catalysts that allow the reactions to be carried out at lower temperatures, therefore increasing the selectivity of the oxidation (see, for example, [6]). However, it is more important that the catalyst itself may regulate the selectivity of the process, leading to the formation of a particular product. The studies of the mechanism of the transition metal salt involvement have shown their role to consist, in most cases, of enhancing the formation of free radicals in the interaction with the initial and intermediate species. 

Adiponitrile undergoes the typical nitrile reactions, eg, hydrolysis to adipamide and adipic acid and alcoholysis to substituted amides and esters. The most important industrial reaction is the catalytic hydrogenation to hexamethylenediarnine. A variety of catalysts are used for this reduction including cobalt—nickel (46), cobalt manganese (47), cobalt boride (48), copper cobalt (49), and iron oxide (50), and Raney nickel (51). An extensive review on the hydrogenation of nitriles has been recendy pubUshed (10). 

Catalysts used for preparing amines from alcohols iaclude cobalt promoted with tirconium, lanthanum, cerium, or uranium (52) the metals and oxides of nickel, cobalt, and/or copper (53,54,56,60,61) metal oxides of antimony, tin, and manganese on alumina support (55) copper, nickel, and a metal belonging to the platinum group 8—10 (57) copper formate (58) nickel promoted with chromium and/or iron on alumina support (53,59) and cobalt, copper, and either iron, 2iac, or zirconium (62). 

Most commercial sorbic acid is produced by a modification of this route. Catalysts composed of metals (2inc, cadmium, nickel, copper, manganese, and cobalt), metal oxides, or carboxylate salts of bivalent transition metals (2inc isovalerate) produce a condensation adduct with ketene and crotonaldehyde (22—24), which has been identified as (5). 

Copper, manganese and cobalt are oxidation catalysts and must be avoided, in particular for inserts. 

Good behaviour up to 60°C except chlorinated solvents, certain oxidants, aromatic hydrocarbons Copper, manganese and cobalt are oxidation catalysts and must be avoided in particular for inserts Possible for special grades... 

The distribution of by-products originating from the methyl group in acetaldehyde oxidation is significantly different for each catalyst. Typical results are presented in Table II. Methane is the predominant by-product with cobalt acetate, while methane and carbon dioxide and methyl esters and carbon dioxide predominate with manganese and copper acetates, respectively. 

The oxides of zinc, cadmium, manganese, nickel, cobalt, and chromium and their mixtures are satisfactory catalysts. In a later work Dolgov and Golodnikov (6) developed an activated copper catalyst and produced a mixture of esters and ketones from alcohol. The reactions proceed by ester mechanism, and at lower temperatures (275°-300°) the formation of esters predominates. This ketone synthesis is equally applicable to higher members of the primary alcohol series. 

Complex oxides of the perovskite structure containing rare earths like lanthanum have proved effective for oxidation of CO and hydrocarbons and for the decomposition of nitrogen oxides. These catalysts are cheaper alternatives than noble metals like platinum and rhodium which are used in automotive catalytic converters. The most effective catalysts are systems of the type Lai vSrvM03, where M = cobalt, manganese, iron, chromium, copper. Further, perovskites used as active phases in catalytic converters have to be stabilized on the rare earth containing washcoat layers. This then leads to an increase in rare earth content of a catalytic converter unit by factors up to ten compared to the three way catalyst. 

Other catalysts and combinations have also been claimed for the process. Thus, metals such as copper, cobalt, nickel, iron, either alone, mixed, or with the addition of oxides of other metals as manganese, chromium, magnesium or calcium or mixed oxides which are active synthetic alcohol catalysts as mixtures of oxides of zinc, magnesium, chromium, manganese, etc., are catalysts for the reaction. 

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