Cobalt Gets a New Look for Fischer-Tropsch

The Fischer-Tropsch (FT) process converts synthesis gas (a mixture of carbon monoxide and hydrogen) into hydrocarbons via a reaction that takes place on the surface of cobalt- or iron-based catalysts. Although several major companies use this process industrially, mainly for the production of synthetic fuels, its economic viability depends on the price of crude oil. One way to improve the economics of Fischer-Tropsch is to capitalize on its ability to produce lower olefins (ethylene, propylene, and butylene), which are building blocks for polymers, solvents, cosmetics, and detergents. The selectivity of industrial-scale Fischer-Tropsch-to-olefins (FTO) processes to produce C2–C4 unsaturated hydrocarbons, however, is low.

Research groups have attempted to develop a catalyst with high selectivity for light olefins, low selectivity for methane, and high stability. Using cobalt-based catalysts in the FTO reaction produces a large portion of undesired methane, while the use of iron-based catalysts requires high temperatures and produces carbon that deactivates the catalyst. One notable development, by scientists at Utrecht Univ., is of an iron-based catalyst modified with promoter compounds that achieved a 60% selectivity for C2–C4 olefins; that reaction required high temperatures (300–350°C), however.