Exelus SynGas to Liquids Technology – ExStol

The Fischer-Tropsch (FTS) reaction has recently become a subject of renewed interest, particularly in the context of the conversion of remote natural gas to liquid transportation fuels. The main incentives for this conversion are the increased availability of natural gas in remote locations for which no nearby markets exist, and the growing demand for middle distillate transportation fuels.

Natural gas can be converted to carbon monoxide and hydrogen (synthesis gas) via existing or newly developed processes such as steam reforming, carbon dioxide reforming, partial oxidation and catalytic partial oxidation, followed by the Fischer-Tropsch Synthesis (FTS) reaction. An important issue in Fischer-Tropsch synthesis is the strong exothermicity, and it corresponds to a theoretical adiabatic temperature rise of about 1600 K at complete conversion.

Multi-tubular fixed-bed and slurry bubble column reactors have been the reactors of choice for low temperature Fischer–Tropsch synthesis. The large support particles in fixed-bed reactors result in poor intra-particle mass transfer characteristics and the space–time yield is limited by heat transfer in the catalyst bed. The slurry system gives rise to significantly improved mass transfer characteristics within the catalyst particles, but the separation of the catalyst from the product can be troublesome. Back-mixing renders the slurry reactor less efficient in terms of reactor volume than a plug flow reactor.

Exelus has applied the EnCat principle to develop a unique catalyst system that is able to integrate the benefits of a fixed-bed reactor (plug-flow and easy scale-up) with the high-heat transfer rates and low pore-diffusion barriers of slurry bubble column reactor in a single “intensified” reactive system. The new catalyst system called the HyperCat is able to provide a high-efficiency catalytic system in a fixed-bed configuration while significantly reducing heat-transfer requirements.