The process is named after Franz Fischer and Hanz Tropsch, who reported the formation of an oily liquid due to hydrogenation of carbon monoxide on alkalized-iron turnings. It was extensively used during the Second World War for producing oil and gasoline from coal. Although the process has evolved over the years and a lot of data for the reaction between hydrogen and carbon monoxide made available, research on catalyst development and kinetics still prevails. The process, also known as ‘Hydrocol Process’ or ‘Synthine Process’ is primarily used to obtain wax and liquid organic compounds - straight and branched paraffins and α-olefins, methanol and higher alcohols.
The Fischer-Tropsch catalysts are based on iron (Fe), cobalt (Co) or ruthenium (Ru) as the active metal. The costs for Fe-based catalysts are low, but they have problems like low wax selectivity, deactivation, and inhibition of the productivity by water at large syngas conversions. Ru based catalysts have high activity but their utilization is limited to scientific studies because of its high price. However cobalt based catalysts are stable and allow high syngas conversions, promoting the formation of heavy wax. Cobalt is superior in terms of catalyst life and does not favor the water gas shift reaction.
The F-T synthesis converts syn-gas into a variety of product mixture consisting of linear and branched hydrocarbons and oxygenated products. The main products are linear. The intrinsic rate equations for the hydrocarbon forming for the cobalt and iron based catalysts are based on Langmuir-Hinshelwood-Hougen-Watson (L-H-H-W).
