Molybdenum catalysts, and

In this paper, the results of the isomerization of hexane, heptane and octane over a Mo2C-oxygen-modified-catalyst, a Mo03-carbon-modified catalyst and a Pt//l-zeolite catalyst, at atmospheric pressure, are presented. Also, the results for a conventional Pt/Al203 catalyst are presented for the isomerization of hexane. Then, the effect of pressure on the isomerization of heptane and octane over the molybdenum catalysts and the Pt//l-zeolite catalyst is shown. Finally, the ability of the molybdenum catalysts to catalyse the isomerization reaction at high conversion with high selectivity even with hydrocarbons larger than hexane is demonstrated this is not possible over the Pt catalysts. The differences between the catalysts are discussed in terms of the reaction mechanisms. 

Some further discussion of the differences in the isomerization mechanisms between the two molybdenum catalysts and the platinum catalysts must be made. A mechanism involving cyclic intermediates has been proposed for a number of catalysts including platinum supported on alumina.27 However, this is unlikely over the molybdenum catalysts which... 

Other metals have also been recently used with this class of substrate. For example, a molybdenum catalyst and ligand 64 promote the alkylation between 52 (R=Ph, X=0C02Me) and dimethyl malonate to provide the branched prod-... 

RCM has attracted much attention and has seen a tremendous increase in synthetic applications over the last decade <2000CR2963, 2006JOM(691)5129>. In this reaction, two C-C multiple bonds, such as double and double, or double and triple in the same molecule, are converted to unsaturated carbocycles or heterocycles in the presence of a metal carbene complex. The versatility of Schrock s molybdenum catalyst and Grubbs ruthenium complexes 68 and 69 (Scheme 10) in carbo- and heterocyclizations, respectively, of very different ring sizes were demonstrated <2000CR2963, 2006JOM(691)5129>. 

Figure 5 Is a histogram showing the distribution of pore volume vs. pore diameter for alumina carrier, fresh cobalt molybdenum catalyst and used cobalt molybdenum catalyst. There was a slight change In mode diameter when the carrier was loaded with about 20% active metal oxides. The pore volume was reduced from 0,60 to 0.53 ml/g. However, accumulation of about 17% coke during the processing of West Coast resld greatly shifted the mode downward and reduced the total pore volume from 0.53 to 0.30 ml/g. (All of these pore volumes have been normalized to 1.0 gram of alumina).

P20s-Et3N, trichloromethyl chloroformate, trimethylamine A -oxide, ° 2,4,6-trichlorotriazine, a molybdenum catalyst and KI and... 

Hydrogenation is currently the most important method for pretreatment of coke oven benzole. The BASF/Scholven process has proved particularly effective, operating at temperatures between 300 and 400 °C with molybdenum or cobalt/ molybdenum catalysts and treating the benzole with various gases containing hydrogen, under pressure (20 to 50 bar). By this process the sulfur content of the refined product is reduced to below 0.5 ppm. 

Nomura and co-workers reported that norbomene-based macromonomers of the following structure (Fig. 15) containing ring-opened poly(norbornene) derivatives in the side chain can be prepared efficiently by the ROMP using well-defined molybdenum catalysts and subsequent end-group reactions (412,413). 

Values of kjk were 25 6 for a molybdenum catalyst and much higher, 75—155, for tungsten catalysts [38]. The only reaction observed using [W(=CPh2)(CO)5] and a mixture of CH2==CHMePh and CH2=CMePr was exchange of the methylene groups [39]. 

As the scope of the reaction increased, the name Olefin Metathesis was introduced by Goodyear, who also pioneered the use of homogeneous catalysts. The reaction had first been recognized during experiments on the development of a heterogeneous catalyst to replace mineral acids in alkylation reactions. Molybdenum hexacarbonyl catalyst supported on alumina produced 2-pentene (40%) from mixed n-butenes together with propylene (51%) and hexene (9%). Tungsten hexacarbonyl was less active than the molybdenum catalyst, and in total contrast, it was found that chromium hexacarbonyl acted as a polymerization catalyst. 

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