Pilot Test for Fischer-Tropsch Synthesis Using a Fixed Bed Compact Heat Exchange Reactor

A fixed-bed compact heat exchange reactor (CHER) was designed and constructed for by Chart Fischer-Tropsch (FT) reaction. This reactor contained a plate-fin structure with layers of mini-channels
(channels having ~5 mm equivalent diameter) containing a total of 80 g of cobalt based catalyst, that were sandwiched by coolant layers. With this structure and its arrangement, the heat of the reactor can be removed promptly. The test results proved that the reactor had the capability to control the temperature evenly without temperature run away.

The design structure of the reactor allowed for nearly isothermal operation of the FT reaction. The peak bed temperature measured was typically within about 2ºC of the coolant stream. Catalyst deactivation as a function of time on line was much less in this reactor than typical packed bed FT reactors. It was not seen any significant deactivation during the test period of near 1000 hour. Methane selectivity was generally 7-10% with the catalyst used, which was much lower than previous test results when using a catalyst with a larger particle diameter. Relatively High conversion was achieved using reasonable space velocities. The production rate of liquid hydrocarbons recovered were 16-20 g/hr at 215ºC, and 25-26 g/hr at 222ºC.

In comparison with FT reaction in CSTR where the reaction is considered isothermal, the performance in fixed bed CHER reactor is comparable in activity for CO conversion, but with insignificant degradation over the test period and constant low selectivity in methane.

The test results suggested that fixed bed CHER is an ideal solution for small scale FT commercial application.