Carbon monoxide Fischer-Tropsch process

Another important association reaction is hydrocarbon formation by carbon-carbon bond closure. This occurs with hydrocarbon fragments in the presence of hydrogen or from carbon monoxide (Fischer-Tropsch process). The surface reaction... 

Catalysts not only accelerate a chemical reaction, but also help to channel a reaction to produce a desired product. This selectivity does not contradict the fact that the position of equilibrium itself cannot be influenced. It only means that under given circumstances, one of the many possible spontaneous parallel reactions will be considerably more accelerated than the others. For example, the process of hydrogenating carbon monoxide (Fischer-Tropsch synthesis) can produce methanol (catalysts ZnO, Cr203) or unsaturated hydrocarbons (catalyst Fe), depending upon the type of catalyst used and the reaction conditions. In contrast, we use the term specificity if a catalyst only affects certain substances. Very high selectivity and specificity can be found in reactions catalyzed by enzymes. These are very important reactions that will be gone into more detail in the next section. 

Fischer-Tropsch Process. The Hterature on the hydrogenation of carbon monoxide dates back to 1902 when the synthesis of methane from synthesis gas over a nickel catalyst was reported (17). In 1923, F. Fischer and H. Tropsch reported the formation of a mixture of organic compounds they called synthol by reaction of synthesis gas over alkalized iron turnings at 10—15 MPa (99—150 atm) and 400—450°C (18). This mixture contained mostly oxygenated compounds, but also contained a small amount of alkanes and alkenes. Further study of the reaction at 0.7 MPa (6.9 atm) revealed that low pressure favored olefinic and paraffinic hydrocarbons and minimized oxygenates, but at this pressure the reaction rate was very low. Because of their pioneering work on catalytic hydrocarbon synthesis, this class of reactions became known as the Fischer-Tropsch (FT) synthesis. 

In the Fischer-Tropsch process, carbon monoxide reacts with hydrogen in the presence of a solid catalyst, with the formation of a mixture of hydrocarbons. The composition of the product varies considerably with the catalyst and the operating conditions. The mixture may include (in addition to hydrocarbons) alcohols, aldehydes, ketones, and acids. 

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... 

The Fischer-Tropsch process is of considerable economic interest because it is the basis of conversion of carbon monoxide to synthetic hydrocarbon fuels, and extensive work has been done on optimization of catalyst systems. 

Synthine [Synthetic benzin] An early version of the Fischer-Tropsch process in which a mixture of carbon monoxide and hydrogen was passed over an iron catalyst and thereby converted to a complex mixture of oxygenates. 

The fact that surface structure, in particular steps and coordinatively unsaturated sites, has an influence on the state and reactivity of carbon monoxide is entirely in keeping with the empirical correlation (Fig. 6) between heat of adsorption, electron binding energies, and molecular state. Elegant studies by Mason, Somorjai, and their colleagues (32, 33) have established that with Pt(lll) surfaces, dissociation occurs at the step sites only, and once these are filled carbon monoxide is adsorbed molecularly (Fig. 7). The implications of the facile dissociation of carbon monoxide by such metals as iron, molybdenum, and tungsten for the conversion of carbon monoxide into hydrocarbons (the Fischer-Tropsch process) have been emphasized and discussed by a number of people (32,34). 

Fischer-Tropsch process (or synthesis). The manufacture of synthesis gas (carbon monoxide and hydrogen) by passing steam over hot coal and the subsequent production of organic compounds from the synthesis gas. 

After World War II, direct liquefaction of coal became uneconomical as the use of lower-cost petroleum products became more widespread. However, the German process of indirect coal liquefaction, the Fischer-Tropsch process, continued to hold some interest. The Fischer-Tropsch process first involved production of a carbon monoxide and hydrogen-rich synthesis gas by the controlled gasification of coal followed by a catalytic reaction process to yield a valuable mixture of hydrocarbon products. Simplified Fischer-Tropsch reactions are shown by the following equations ... 

Methanation is one of a more general class of Fischer-Tropsch processes in which carbon monoxide and carbon dioxide are hydrogenated to form various light hydrocarbons and water. Although the primary reaction using a nickel on alumina catalyst is the methanation of carbon monoxide, appreciable side reactions can occur in the methanation system. The reactions in the methanation system are shown in Table I and include carbon dioxide... 

In the Fischer-Tropsch process, as developed commercially by the Ruhrchemie A.G. in Germany (30) in 1935-40, synthesis gas containing 2 volumes of hydrogen per volume of carbon monoxide was compressed to about 7 atmospheres and passed through a granular... 

The history of the oxo reaction is also noteworthy. It was developed originally in Germany in the years following World War 1. At that time, the German chemical industry was faced with inadequate supplies of petroleum. Many German chemists therefore turned to research on ways by which hydrocarbons could be synthesized from smaller building blocks, particularly carbon monoxide and hydrogen derived from coal. The success achieved was remarkable and led to alkane and alkene syntheses known as the Fischer-Tropsch process ... 

Fischer-Tropsch process a process for synthesizing hydrocarbons and oxygenated chemicals from a mixture of hydrogen and carbon monoxide. 

Oxygen-blown ATR with natural gas is used today in very large units that generate a mixture of CO and H2 for the Fischer-Tropsch process or methanol synthesis. This is attractive in part because the units can produce the hydrogen-to-carbon monoxide ratio needed in the synthesis step. Since the heat of reaction is added by combustion with oxygen, the catalyst can be incorporated as a fixed bed that can be scaled up to achieve further benefits of larger plant size in both the... 

Paraffin, Synthetic, occurs as a white wax that is very hard at room temperature. It is synthesized by the Fischer-Tropsch process from carbon monoxide and hydrogen, which are cata-lytically converted to a mixture of paraffin hydrocarbons the lower-molecular-weight fractions are removed by distillation, and the residue is hydrogenated and further treated by percolation through activated charcoal. It is soluble in hot hydrocarbon solvents. 

The Fischer-Tropsch process Reaction of carbon monoxide with hydro- 9,16.28, 32,44, gen in the presence of a solid catalyst to produce a mixture of 58,64.65,66. hydrocarbons, alcohols, aldehydes, ketones, and acids depending upon 67, 68. 69,85, operating conditions and the nature of the caialyst 105... 

Synthesis gas contains a mixture of carbon monoxide and hydrogen and can be obtained from the combusfion of coa) or natural gas. This gas can be used to produce synthetic crude by the Fischer-Tropsch reaction. Describe two industrial reactors used to convert synthesis gas to a mixture of hydrocarbons by the Fischer-Tropsch process. 

Catalysis by Metal Ousters in Zeolites. There is an increasing interest in the use of metal clusters stabilized in zeolites. One objective of such work is to utilize the shape and size constraints inherent in these support materials to effect greater selectivities in typical metal-catalysed reactions. Much work has been concerned with carbon monoxide hydrogenation, and although the detailed nature of the supported metals so obtained is not well understood, there is clear evidence of chain limitation in the Fischer-Tropsch process with both RuY zeolites and with HY and NaY zeolites containing Fe3(CO)22- In the former case there is a drastic decline in chain-growth probability beyond C5- or C10-hydrocarbons depending upon the particle size of the ruthenium metal. 

Where the Fischer-Tropsch process has been used on an industrial scale, iron or cobalt are the essential catalyst components. Technical catalysts also contain oxidic promoters, such as alumina and potassium oxide. Ruthenium and nickel are most attractive for academic research since they produce the simplest product packages. Nickel is used for methanation (production of substitute natural gas and removal of carbon monoxide impurities from hydrogen). 

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