Fischer-Tropsch synthesis metathesis reaction

Group II The activity drops more than the Ni surface concentration (Fig. 13), i.e., at least about 20 times. However, for several reactions this drop is two or more orders of magnitude. The reactions included in this group are methanation and Fischer-Tropsch synthesis, isomerization, de-hydrocyclization or hydrogenolysis of alkanes, ether formation from alcohols, metathesis of alkylamines, and possibly other reactions. 

The ability of a p-carbene to react with an unsaturated hydrocarbon and form an enlarged dimetallocycle encourages speculation over their role in such processes as alkene metathesis and Fischer-Tropsch synthesis. In Scheme 6 a possible mechanism for metathesis initiated by a p-carbene is presented, owing much to other workers (T7,22). Reactions of p-carbenes with alkenes are under investigation in our laboratory. Recently Pettit has observed that the p-methylene complex [Fe2(C0)8(p-CH2)] generates propene when subjected to a pressure of ethene and has also suggested the intermediacy of a three-carbon dimetallocycle (23). 

The discussed reactions of carbene and carbyne complexes show that they have essential significance as catalysts or unstable transient intermediate compounds in such catalytic processes as metathesis of olefins and other unsaturated compounds, Fischer-Tropsch synthesis, syntheses of cyclopropanes from diazoalkanes and olefins, and polymerization of olefins and alkynes as well as in organic synthesis. Except for alkynes [reaction (5.132) ] some compounds containing double bonds react with carbon monoxide and carbene ligands to form bonds with those groups. Examples of such compounds are enamines, ynamines, and Schiff bases. The JV-vinylpyrrolidone (enamine), methoxyphenylcarbene, and excess of CO (higher pressure) react to furnish enaminoketone. 

For its relevance, propene is one of the most important olefins. Propene is obtained mainly from naphtha steam cracking as a coproduct with ethene, and also as a coproduct from fluid catalytic cracking (FCC) units at refineries. Relatively small amounts are produced by propane dehydrogenation and by Fischer-Tropsch synthesis. Because of the strong global demand for polypropene, acrylonitrile, 0x0 alcohol, and acrylic acid products, present propene supply from conventional sources cannot fulfill the market needs. An alternative route to propene is by applying the metathesis reaction for the conversion of a mixture of ethene and 2-butene into propene (Equation [16.2]). 

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