Carboxylic acids Fischer-Tropsch process

Except for cobalt systems, other metals also demonstrate activity in the Fischer-Tropsch process. Mo/HZSM-5 turned out to be active in FT synthesis [98], The catalysts were tested at a low H /CO molar ratio 1.0, this composition being typical for biomass gasification. Liquid hydrocarbons obtained on Mo/HZSM-5 at 573 K were presented by alkylaromatics and lower branched and cyclic alkanes. The formation of aliphatic hydrocarbons was close to zero. The gas products included Cj-C alkanes. Higher alcohols and carboxylic acids (C,-Cg) were observed in the aqueous phase. The formation of hydrocarbons on Mo/zeolite is accounted for by the bifunctional zeolite acidity and molybdenum metal activities via alcohols as intermediates. The zeolite Y was also found to be a good support for Mo in the FT reaction. 

The first commercial Fischer-Tropsch facility was commissioned in 1935, and by the end of the Second World War a total of fourteen plants had been constructed. Of these, nine were in Germany, one in France, three in Japan, and one in China. Both German normal-pressure and medium-pressure processes (Table 18.1) were employed. The cobalt-based low-temperature Fischer-Tropsch (Co-LTFT) syncrude produced in these two processes differed slightly (Table 18.2), with the product from the medium-pressure process being heavier and less olefinic.11 In addition to the hydrocarbon product, the syncrude also contained oxygenates, mostly alcohols and carboxylic acids. 

The refinery design included the recovery of nonacid oxygenates in the Fischer-Tropsch aqueous product that are lighter boiling than water.30 The oxygenate chemicals recovered from the aqueous product included methanol (mainly from Fe-LTFT), ethanol (from Fe-HTFT, Fe-LTFT, and acetaldehyde hydrogenation), as well as mixed heavier alcohol and ketone streams. The carboxylic acids were not recovered and were processed with the wastewater. 

Oxidative fission of a carbon-carbon bond of aliphatic hydrocarbons is generally devoid of preparative interest because the chain may be broken at various places and mixtures of carboxylic, dicarboxylic, and hydroxy carboxylic acids with other oxidation products are formed. If, however, certain experimental conditions are precisely maintained, alkanes of high molecular weight can be oxidized catalytically by air, e.g., by the Fischer-Tropsch-Gatsch process, reasonably homogeneously to fatty acids of medium chain length (C10-C18), and this has assumed much industrial importance for the manufacture of soap. 

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