Fischer-Tropsch test unit

Studies of the Fischer-Tropsch synthesis on nitrided catalysts at the Bureau of Mines have been described (4,5,23). These experiments were made in laboratory-scale, fixed-bed testing units (24). In reference 5, the catalyst activity was expressed as cubic centimeters of synthesis gas converted per gram of iron per hour at 240°C. and at a constant conversion of 65%. Actually, the experiments were not conducted at 240°C., but the activity was corrected to this temperature by the use of an empirical rate equation (25). Conditions of catalyst pretreatment for one precipitated and two fused catalysts are given in Table IV. 

Fig. 2. (a) A SEM image of the alumina-supported cobalt catalyst A after a Fischer-Tropsch synthesis test run in the demonstration unit, (b) Relative mean PSD values of the supported catalyst (catalyst B) after an 8 months test tun on the Pilot Plant slug-flow reactor. 

The test reactor was a 13 mm i.d. quartz tube fitted to a process unit equipped with gas supplies, flow and temperature controllers, a furnace, and a gas chromatograph with appropriate columns and detectors. The sample was loaded into the reactor, purged and/or reduced and heated to the test temperature (200-250°C). With the feed gas (C2H4 and O2, CO2 and H2, or CO and H2) flowing, conversion and product composition were measured. Conversions were maintained as low as possible so that differential rates could be determined. In the case of Fischer-Tropsch synthesis, measurements were made at higher conversions to check selectivities. 

As in any slurry based process, complex hydrodynamic behavior complicates the scale up to a commercial size unit. Therefore, computational modeling supported by cold flow x-ray mapping tests on a pilot reactor prototype has been used to assist the reactor development efforts. Operation of a 2 bpd Fischer Tropsch pilot plant began in 2003 and has continued through 2004 at the BP Chemicals Saltend site. 

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