Processes Related to the Fischer-Tropsch Synthesis

The catalyst was prepared by burning pure iron in oxygen to form a molten mass of oxide. Aluminum nitrate and potassium nitrate are then added to the melt and the fused mixture cooled and crushed to 1 to 3 mm. particle size. The finished preparation contained 97% Fe304, 2.5% Ala03, 

2 to 0,6% K2O, 0.16% sulfur, and 0.03% carbon. Its bulk density, after crushing, was about 2.0. This catalyst was reduced for 50 hours in pure dry hydrogen at about 450° C. About 2000 volumes hydrogen/hour are passed through 1 volume of catalyst at a linear velocity of at least 20 cm. second. The reduced catalyst is transferred in an atmosphere of carbon dioxide to the reactor. 

The synol process is of interest in a discussion of the Fischer-Tropsch reaction for the following reasons  

The reaction in the first stage probably is a homogeneous catalytic reaction, with either cobalt carbonyl or cobalt hydrocarbonyl as the catalyst. The insensitivity to sulfur poisoning, and the fact that any finely divided reactive cobalt compound may be used, agrees well with this assumption. 

The aldehydes and alcohols produced are a mixture of normal and iso-compounds. This is due not only to the orientation of the hydrogen with respect to the C-CO bonds in the initial reaction complex but also to the isomerization of the olefin under the process conditions. It may be significant that nickel carbonyl does not readily shift the olefin double bond under the 0X0 process conditions, and nickel compoimds are very poor catalysts for the process. From isooctene 32% n-nonyl alcohol, and from propylene 50% n-butyl alcohol are obtained, the remainder of the products being isoalcohols. In general, using a-olefins as raw material, one obtains about 60% isoalcohols. The synthesis will not occur unless a labile hydrogen atom is available in the olefin reactant. With diolefins the reaction takes place at only one double bond. 

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