Fischer-Tropsch synthesis insertion

In Fischer-Tropsch synthesis the readsorption and incorporation of 1-alkenes, alcohols, and aldehydes and their subsequent chain growth play an important role on product distribution. Therefore, it is very useful to study these reactions in the presence of co-fed 13C- or 14 C-labeled compounds in an effort to obtain data helpful to elucidate the reaction mechanism. It has been shown that co-feeding of CF12N2, which dissociates toward CF12 and N2 on the catalyst surface, has led to the sound interpretation that the bimodal carbon number distribution is caused by superposition of two incompatible mechanisms. The distribution characterized by the lower growth probability is assigned to the CH2 insertion mechanism. 

Insertion of CO into the metal-methyl bond of 1 followed by reduction and elimination of water would yield a metal ethyl species (3). This latter set of reactions represents, formally at least, a possible growth sequence for the Fischer-Tropsch synthesis. 

The mechanisms proposed over the last 50 years for the Fischer-Tropsch synthesis, principally on the basis of studies using heterogeneous catalyst systems, may be divided into three main classes (a) metal-carbide mechanisms (b) hydroxyl carbene, =CH(OH), condensation mechanisms and (c) CO insertion mechanisms. 

The catalysts derived from supported iron clusters exhibit in Fischer-Tropsch synthesis a high selectivity for propylene. Those catalysts are also selective for the stoechiometric homologation of ethylene to propylene and of propylene to n and iso butenes. The results are explained on the basis of a new mode of C-C bond formation which implies < - olefin coordination to surface methylene fragments or methylene insertion into a metal alkyl bond. 

Fischer-Tropsch synthesis was performed in a Berty micro reactor. The carbon monoxide, hydrogen and argon and hydrogen flows were controlled with Brooks flow-controllers. The reactor, gas outlet and hot trap lines were heated by means of electrical heaters each of which was controlled by separate temperature controllers. Inserting a thermocouple into the catalyst bed controlled the catalyst bed temperature. 

The versatility of CO as a synthon also stems from its ability to undergo insertion reactions into a variety of metal-heteroatom bonds. The migratory insertion of CO into transition metal-hydride bonds, while thermodynamically unfavorable, generates metal-formyl complexes M-C(0)H (Equation (19)), a few examples of which have been isolated independently. This reaction is assumed to be a key step in both the homogeneous and heterogeneous catalytic hydrogenation (i.e., reduction) of CO, including the Fischer-Tropsch synthesis of hydrocarbons and... 

The insertion of ligated CO into metal-carbon -bonds (or rather the migration of an alkyl group to a coordinated CO) is a key step in a variety of synthetic and catalytic important processes, e.g., in hydroformylation (145), the Fischer-Tropsch reaction (146) and the synthesis of acetic acid from methanol (147). 

Various unsaturated compounds can be inserted into the metal alkyl, aryl, and alkenyl complexes to give new organometallic complexes having various functional groups. The insertions of carbon monoxide (CO) and isocyanide (CNR) into transition metal-carbon a-bond are particularly important processes, since a carbon unit can be increased in the process and the acyl type complexes formed by the insertion processes can be subjected to further transformations to synthesize useful organic compounds. For example, the CO inserhon constitutes a fundamental step in industrially important processes such as hydroformylation of olefins, acetic acid synthesis from methanol and CO, Fischer-Tropsch process, amidocarbonylation, olefin and CO copolymerizahon processes as well as in a variety of laboratory syntheses of carbonyl containing compounds. 

Coated foams have been integrated for co-heating the steam reforming of natural gas by the catalytic partial oxidation of natural gas in adjacent microsized slits for easy scale-up for offshore synthesis gas production and subsequent Fischer-Tropsch or methanol synthesis [46]. The catalyst was solution coated on a 40 pores cm foam and inserted in 640 pm slits. No information was given on the catalytically active species used. The conversion which was given exceeded 95%. However, this is the value yielded after combustion of the produced synthesis gas (exhaust). 

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