PEP Review 2000-13
Fischer-Tropsch Synthesis Via Reactive Distillation
Published: April 2003
Fischer-Tropsch synthesis (FTS) generally involves the synthesis of hydrocarbons and oxygenates from synthesis gas (syngas) consisting primarily of a mixture of CO + H2. The types of hydrocarbons produced can include olefins such as ethylene and propylene, and an extremely wide range of saturated hydrocarbons ranging from methane and ethane to long "straight chain" paraffinic waxes. The oxygenates produced primarily consist of alcohols such as methanol and ketones such as acetone. When configured to maximize the production of paraffinic hydrocarbons, the resulting intermediate product mix is often described as "synthetic crude oil" (syncrude). Such syncrudes can be readily refined into desirable distillate fuel fractions such as kerosene, naphtha, and heating oil using conventional petroleum refining techniques. The kerosene can be further refined or blended into high quality diesel or jet fuel products while the naphtha can be further refined into gasoline or used as a thermal cracking feedstock for olefins production.
For the large-scale production of middle distillates and diesel fuel via FTS based gas-toliquids (GTL) processing, the use of slurry phase Fischer-Tropsch reactor configurations appear to be generally favored by most technology developers. The slurry typically consists of mixture of catalyst and waxy paraffinic hydrocarbons. Potential drawbacks of such reactors appear to be the need for substantial liquid and syngas recycle streams as well as the need for large and costly heat transfer surface requirements to achieve the heat removal and mixing desired for this highly exothermic heterogeneous reaction environment. It has recently been proposed in the patent literature that the use of reactive distillation an alternative to conventional slurry phase FTS may facilitate such heat removal and mixing as well as improve product yields. Another potential advantage of reactive distillation would be the simplification of downstream product purification requirements. In this review, we perform a preliminary evaluation of our design concept for such a reactor system as applied to GTL diesel production.