(707a) Highly Efficient Fischer-Tropsch Synthesis in Ionic Liquids

Fischer-Tropsch synthesis involves production of liquid fuel from synthesis gas. Conventional Fischer-Tropsch processes are intrinsically inefficient as a result of the polymerisation nature of the reaction, which yields a product distribution rather than a single product. In the subsequent upgrading step the hydrocarbons that are too long are ‘cracked’ into molecules with shorter chain length, partly destroying what has been produced in the reaction step. This upgrading step is not only energy intensive, but it also accounts for a significant part of the capital expenditure.

In this work, a novel highly efficient Fischer-Tropsch process is developed that selectively produces hydrocarbons with the desired chain length (diesel) using an ionic liquid as solvent. This innovative process employs the phenomenon that the solubility of hydrocarbons in ionic liquids decreases with increasing hydrocarbon chain length. The polymerisation reaction takes place in a hydrophobic ionic liquid, which dissolves reactants, catalyst and hydrocarbons shorter than the desired product. However, at the moment the desired chain length is reached, the hydrocarbon is no longer soluble in the ionic liquid, and forms a separate layer that floats on top of the ionic liquid, thus avoiding contact with the catalyst and preventing further reaction. The product can be easily withdrawn from the reactor, abandoning the need for a conventional energy- and capital intensive upgrading section.

Process development results of the novel highly efficient Fischer-Tropsch synthesis in an ionic liquid will be presented at the conference.