In Fischer-Tropsch reaction

Modification of the zeolite appears to have affected the selectivity of Ru in these hydrogenation reactions. Exchange of K cations for Na cations in Y zeolite increases the basicity of the support (ref. 9). In Fischer-Tropsch reactions over similar catalysts, Ru/Y catalysts so modified yielded significant increases in the olefinic product fraction at the expense of paraffins. Olefins are believed to be primary products in F-T synthesis, with paraffins being produced from olefins in secondary hydrogenation reactions. In an analogous fashion, the Ru/KY catalyst used in the present study might also be expected to... 

The chemistry of CR fragments ligating metal centers has been a topic of considerable interest since the discovery of the first alkylidyne-metal complexes in E.O. Fischer s Laboratory in 1973 (1). These ligands have been implicated in Fischer-Tropsch reactions (2) and in alkyne metathesis (5). Moreover, the isolation of stable compounds containing carbon-metal triple bonds completed the matrix of bond types represented here ... 

The synthesis of organic molecules in Fischer-Tropsch reactions in early solar nebulae has been suggested by Anders et al. (1971). 

Pettit [44] has stressed the importance of bridge melhylene ligands un transition metal surfaces- Similarities in product formation with CO/H] and surest a common mechanism for both processes, with methylene possibly being formed by carbide hydrogenation in Fischer-Tropsch reactions. 

Hydroxycarbencs(60) are also proposed in Storck and Pichler s mechanisms [7] as intermediates in Fischer-Tropsch reactions ... 

Earl L. Mnetterties et al. Metal clusters as homogeneous catalysts for reduction of carbon monoxide in Fischer-Tropsch reaction... 

The catalytically active phase was assumed to be exclusively a-Fe, and Fe304 was assumed not to be active for the Fischer-Tropsch reaction. Kinetic parameters for the simulations were obtained independently in separate oxidation/reduction studies. Balancing the oxidation and reduction rates for the CO/CO2 and the H2/H2O systems independently and describing the rate of synthesis in Fischer-Tropsch reactions by a standard expression, Caldwell could predict the oscillations with a simplified model for a tubular reactor fairly well. 

The reaction products obtained over K/Cu-Zn-Fe oxides catalyst showed Schulz-Flory distribution. This suggests that C-C bonds were formed under the mechanism similar to that in Fischer-Tropsch reaction. 

Readsorption and secondary reactions of the intiailly produced ct-olefins is an important pathway in Fischer-Tropsch reactions on Fe single crystals Dwyer, D.J., and Somorjai, G.A., J. Catal., 56, 249, (1979). Schulz, H., and Achtsnit,... 

The synthesis of fatty acids by a Fischer-Tropsch-type process as described in this chapter required the use of a catalyst (meteoritic iron) and a promoter. Potassium carbonate and rubidium carbonate were the only compounds evaluated which unambiguously facilitated the production of fatty acids. These catalytic combinations (meteoritic iron and potassium carbonate or rubidium carbonate) also produced substantial amounts of n-alkenes (in excess of n-alkanes) and aromatic hydrocarbons. A comprehensive study of the nonacidic oxygenated compounds produced in Fischer-Tropsch reactions (20,21) was not made. However, in the products analyzed (all promoted by potassium carbonate), long-chain alcohols and aldehydes were detected. 

It has been found that the presence of Lewis acids or protons can accelerate carbonyl insertion reactions, providing another possibility of modifying catalysts. Mixtures of transition metal carbonyls and Lewis acids could in future be of interest as catalysts for CO hydrogenation, for example, in Fischer-Tropsch reactions (Eq. 2-82) [Til]. 

These reactions may occur simultaneously or not, depending on the thermodynamic conditions and especially on the catalyst. In the methanation Ni, catalysts are used, while in Fischer-Tropsch reactions, Fe or Co catalysts are employed. In the reactions for methanol synthesis, mixed oxide catalysts of CuO/ZnO are used, and for the shift reaction, Ni supported catalyst. 

Fig. 12.19 Possible reaction paths in Fischer Tropsch reactions, (a) A suggested scheme involving surface methylene groups.

Trepanier M, Dalai AK, Abatzoglou N. Synthesis of CNT-supported cobalt nanoparticle catalysts using a microemulsion technique role of nanoparticle size on reducibiUty, activity and selectivity in Fischer-Tropsch reactions. Appl Catal A 2010 374 79-86. 

A key chain growth step in Fischer-Tropsch reactions may be the insertion of a methylidene ligand into a metal-alkyl bond. Evidence has been presented that such an insertion occurs in a transient tungsten-methylidene methyl complex [equation (15)] and that this reaction becomes highly favorable when the alkylidene center is electrophilic. 

H. Zhang, C. Lancelot, W. Chu, J. Hong, A. Y. Khodakov, P. A. Chemavskii, J. Zheng, D. Tong, 2009, The nature of cobalt species in carbon nanotubes and their catalytic performance in Fischer-Tropsch reaction, J. Mater. Chem., 19,9241-9249. 

Figure 16.1 The relative rate requirements for the reaction steps in Fischer-Tropsch reaction cycle (schematic).

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