TITLE: Technology development for iron Fischer-Tropsch catalysts.  Quarterly technical progress report for period ending December 1993.

AUTHOR: R. J. O'Brien;   L. Xu;   X. Bi;   P. Eklund;   B. H. Davis.

INST.  AUTHOR: Kentucky Univ., Lexington. Center for Applied Energy Research.

SPONSOR: Department of Energy, Washington, DC.


PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  1993,  18p.



Conversion data as a function of time of synthesis for the two catalysts are shown in Figures 2 and 3. In general the precipitated catalyst is more active than the iron carbide catalyst with syn-gas conversions starting at 80% as compared to 50% for the latter; however, both catalysts deactivated with increasing reaction time. A comparison of the C(sub 2), C(sub 3) and C(sub 4) olefin selectivities at 26% CO conversion (precipitated catalyst-336 hr of synthesis, iron carbide catalyst-122 hr of synthesis) are shown in Figure 4. Surprisingly the precipitated catalyst had a higher olefin content than the iron carbide catalyst. It has been reported that a similar iron carbide catalyst has higher selectivity for the production of olefins than a ''conventionally prepared'' Fe/Co catalyst. The discrepancy may be due in part to comparing the olefin selectivity of the two catalysts at different conversions. Their ''conventional catalyst'' had a C(sub 2)(minus)C(sub 4) olefin content of 37% at 72% conversion compared to 86% olefin at 55% conversion for the iron carbide catalyst. In general the olefin selectivity of a catalyst is highest at low conversions. The iron carbide catalyst of this study produces more hydrocarbons than the precipitated catalyst; furthermore, it produces a higher fraction of C(sub 3) + (86% vs. 84%) and C(sub 5)+ (67% vs. 61%) hydrocarbons (Figure 5).  Correspondingly, the iron carbide catalyst produces less methane and ethane than the precipitated catalyst (Figure 6). These hydrocarbon and C(sub 5)+ selectivities are similar to those reported earlier.