The objective of this research project is to develop the technology for the production of physically robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry phase synthesis reactor development. The catalysts that are developed shall be suitable for testing in the Advanced Fuels Development Facility at LaPorte, Texas, to produce either low- or high-alpha product distributions. Previous work by the offeror has produced a catalyst formulation that is 1.5 times as active as the ''standard-catalyst'' developed by German workers for slurry phase synthesis. The proposed work will optimize the catalyst composition and pretreatment operation for this low-alpha catalyst. In parallel, work will be conducted to design a high-alpha iron catalyst that is suitable for slurry phase synthesis. Studies will be conducted to define the chemical phases present at various stages of the pretreatment and synthesis stages and to define the course of these changes. The oxidation/reduction cycles that are anticipated to occur in large, commercial reactors will be studied at the laboratory scale. Catalyst performance will be determined for catalysts synthesized in this program for activity, selectivity and aging characteristics. The research is divided into four major topical areas: (a) catalyst preparation and characterization, (b) product characterization, (c) reactor operations, and (d) data assessment. Accomplishments for this period are discussed.

This report covers two aspects of the catalyst characterization studies: scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Two types of catalysts are the subject of this report: SEM studies with as-received, pretreated and used samples of a Ruhrchemie type catalyst and TEM examination of four crystal structures of FeOOH and Fe3O4.

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 C2, C3 and C4 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 C2-C4 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 C3 + (86% vs. 84%) and C5+ (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 C5+ selectivities are similar to those reported earlier.

The preparation of binderless iron oxide spheres has been achieved by a novel sol-gel forming procedure. The starting material is a solution of iron (III) 2-ethylhexanoate in mineral spirits. This solution is added dropwise to an ammoniacal solution of methanol. The low viscosity of the methanol causes the formation of small droplets of the iron solution. The immiscibility of the mineral spirit solution in the methanol and the difference in surface tensions cause the droplets to assume a spherical shape. The presence of ammonia and water at low levels in the methanol promotes the hydrolysis of the iron (III) 2-ethylhexanoate, which causes the spherical particles to harden. The iron-containing spheres can then be isolated by filtration. These spheres are the first ones reported to be made of 100% iron oxide and prepared without a binder. In the initial preparations, the spheres are 100 to 200?m in diameter. Some problems remain to be resolved with this new method of preparation.