Fischer-Tropsch synthesis: Process considerations based on performance of iron-based catalysts

Abstract

Alternative reactor configurations and the utilization of a low-alpha versus high-alpha iron-based catalyst are compared for the Fischer-Tropsch synthesis based on actual catalyst performance. The use of coal-derived synthesis gas with a low H 2/CO ratio requires a judicious balance between the rates of the Fischer-Tropsch and water-gas shift reactions. The hydrocarbon space-time yield is considerably increased by using either a reactor with recycle or a series of reactors with low syngas conversion per pass instead of a single-pass reactor with high syngas conversion. The production of gasoline and diesel-range hydrocarbons by downstream processing of the Fischer-Tropsch reaction products involves both hydrocracking and oligomerization. The difference between processing the products from a low-alpha and a high-alpha iron-based catalyst lies merely in the relative sizes of the hydrocracking and oligomerization reactors required. In addition, it is advantageous to use a low-alpha catalyst from the viewpoint of Fischer-Tropsch slurry reactor operation.