Carbonylation reactions Fischer-Tropsch process

The steps in the hydroformylation reaction are closely related to those that occur in the Fischer-Tropsch process, which is the reductive conversion of carbon monoxide to alkanes and occurs by a repetitive series of carbonylation, migration, and reduction... 

An interesting sequel to the Fischer-Tropsch synthesis is the so-called 0X0 reaction. Olefines derived from the Fischer-Tropsch process will react with carbon monoxide and hydrogen in the presence of cobalt carbonyl at temperatures of 110° to 150°C, under pressures of 150 to 200 atmospheres, to yield aldehydes. These can either be reduced to alcohols or oxidized to fatty acids, and they are derived from the petroleum industry... 

USE As reducing agent in metallurgical operations espa-cially in the Mond process for the recovery of nickel in organic synthesis especially in the Fischer -Tropsch processes for petroleum -type products and in the oxo reaction in the manuf of metal carbonyls. 

The reaction increases the Hj content of syngas, CO + Hj mixtures, and can be used in conjunction with the Fischer-Tropsch process. There has been renewed interest in this reaction as a source of for fuel cells. Metal carbonyls of Fe, Ru and Rh, under either acidic or basic conditions, are effective homogeneous catalysts. Fachinetti and co-workers have investigated the speciation and reactivity of Rh CCOju " and RujCCOjjj under acidic conditions. These systems are complicated by reactions such as disproportionation and complexation of the catalyst by the conjugate base of the acid. 

Studies on systems related to proposed intermediates in the Fischer-Tropsch process have shown that whereas [LiBHEts] attacks [Mn(CO)5COR] compounds at a carbonyl carbon, reaction with [(OQjMnCOCOPh] affords a novel metallocycle (Scheme 36). Ring-opening reactions of the metallocycle. 

A related version of great economic interest is the Fischer-Tropsch process for reductive conversion of carbon monoxide to hydrocarbons. This reaction is catalyzed by a number of metals but cobalt and iron have been most closely studied. The key reaction steps are reduction of metal-complexed carbon monoxide and carbonyl insertion reactions. The hydrocarbon chain is built up by a series of successive carbonyl insertion and reduction steps. 

In more or less related reactions, Co2(CO)g is a useful catalyst in carboxylation (viz. alkoxycarbonylation) and a wide range of carbonylation reactions. Both catalysis of the water-gas shift reaction and of Fischer-Tropsch processes have been demonstrated on solid supports and probably involve Co2(CO)8-derived polynuclear carbonyls. ... 

The induction of steric effects by the pore walls was first demonstrated with heterogeneous catalysts, prepared from metal carbonyl clusters such as Rh6(CO)16, Ru3(CO)12, or Ir4(CO)12, which were synthesized in situ after a cation exchange process under CO in the large pores of zeolites such as HY, NaY, or 13X.25,26 The zeolite-entrapped carbonyl clusters are stable towards oxidation-reduction cycles this is in sharp contrast to the behavior of the same clusters supported on non-porous inorganic oxides. At high temperatures these metal carbonyl clusters aggregate to small metal particles, whose size is restricted by the dimensions of the zeolitic framework. Moreover, for a number of reactions, the size of the pores controls the size of the products formed thus a higher selectivity to the lower hydrocarbons has been reported for the Fischer Tropsch reaction. 

The catalyst used in the process was a Fischer-Tropsch cobalt-thoria catalyst. The temperature was usually between 130-160° and a total pressure of 200 atm. of water gas (1II2 ICO) was usually employed. The reaction was carried out first with ethylene and the products were found to consist of a mixture of diethyl ketone and propionaldehyde. As both products contained a carbonyl or oxo group, the reaction was called the Oxo synthesis. Later it was found that ketone production was relatively unimportant aldehydes were almost always the principal... 

The CO used for the carbonylation reaction always contains some hydrogen. The side products in the BASF carbonylation process arise due to Fischer-Tropsch reaction catalyzed by the cobalt catalyst. The high temperatures and pressures used in the BASF process are conditions under which the Fischer-Tropsch reaction with soluble cobalt catalyst can take place. In the Monsanto process the reaction conditions are much milder, and the side-product-forming Fischer-Tropsch reaction is avoided. 

It is possible that a reaction similar to the 0X0 reaction occurs on the surface of catalysts during the synthesis of hydrocarbons and alcohols by the Fischer-Tropsch and the synol processes, and accounts for the small (about 10%) fraction of branched hydrocarbons and isoalcohols produced. In this coimection it is of interest to note that as Pichler (37) indicated, the optimum operating pressures for nickel, cobalt, iron, and ruthenium Fischer-Tropsch catalysts increase in the order mentioned, and the difficulty of metal carbonyl formation also increases in this order. 

Much of the justification for the extensive study of transition metal cluster chemistry is embedded in the assumption that reactions of metal clusters are realistic structural models for reactions at metal surfaces in such processes as heterogeneous catalysis (9,10,11). For example, the metal carbonyl clusters, Ir4(CO)i2 and Os3(CO)i2, were demonstrated to be effective homogeneous catalysts for methanation (12). Additionally, Demitras and Muetterties (13) have found Ir4(CO)i2 to be a homogeneous catalyst in the Fischer-Tropsch synthesis of aliphatic hydrocarbons. Homogeneous catalysis of the water gas shift reaction by metal carbonyl clusters (e.g., Ru3(CO)i2) in alkaline solution has been reported by Laine, Rinker, and Ford (14), and more recently by Pettit s group (15). Nevertheless, mononuclear metal carbonyls (e.g., Fe(CO)s and the group VIb metal hexacarbonyls) have been demonstrated to have considerable activity above 120°C as soluble catalysts for Reaction 2 (16),... 

One of the earliest reactions involving the insertion of CO into a Cn-olefin molecule to produce an aldehyde with one greater Cn+i carbon number is the so-called hydroformylation or "0x0 " reaction. The 0x0 reaction is carried out over homogeneous catalysts, rhodium or cobalt carbonyls, and is an important industrial process. Recently the production of acetic acid, acetaldehyde, and glycol from CO and H2 over heterogeneous and homogeneous rhodium catalysts have been reported. Straight-chain saturated hydrocarbons are not the only molecules that may be produced in the Fischer-Tropsch reaction. There have been... 

Formation of alcohols from olefins, carbon monoxide and hydrogen in the liquid phase in the presence of catalysts (metallic cobalt compounds such as Raney cobalt or cobalt carbonyls) at 115-190° and high pressures (100-200 atmospheres) in a Fischer-Tropsch-tvpe reaction q.v. The process is sometimes carried out in two stages, the initial stage giving largely aldehydes which are then reduced to the alcohols. 

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