Characterization of Fe{sub 1-x}S catalysts synthesized from ferrihydrites under DCL condition
- Univ. of Kentucky, Lexington, KY (United States); and others
Recently, considerable effort has been made to develop low cost, highly dispersed iron-based catalysts for direct coal liquefaction (DCL). Most iron-based catalysts are in fact the catalyst precursors as the catalysts convert to Fe{sub x-1}S (pyrrhotite) under DCL reaction conditions. There has been less work reported on the pyrrhotite phase, in terms of its morphology and structure, and how they influence DCL activity. In the past, we have extensively investigated the structure and DCL activity of ferrihydrite (FHYD), a highly dispersed iron oxide with surface area >200 m/g and average particle size of 30-50 {Angstrom}. The major drawback of this material as a catalyst is that the small particles quickly agglomerate and transform to a low surface area hematite ({alpha}-Fe{sub 2}O{sub 3}) at T > 200{degrees}C. Moreover, the presence of surface adsorbed water molecules accelerates the agglomeration and phase transformation. This problem has been resolved by chemisorption of small amounts of impurity anions at the surface of ferrihydrite. The impurity anions block the crystal growth sites and thereby effectively inhibit the phase transformation to hematite, allowing the catalyst to maintain its dispersion. A number of binary ferrihydrite catalysts (M/FHYD, M/Fe {approx} 5%) with M = Si, Mo, P, and citric acid (CA) have been synthesized in our laboratory. DCL tests using Si/FHYD and CA/FHYD show significant increases of coal-liquid conversion over that obtained from thermal reaction, or with pure ferrihydrite. In this paper, we report the characterization of pyrrhotite catalysts synthesized under simulated DCL conditions using binary ferrihydrites as the catalyst precursors.
- DOE Contract Number:
- FC22-90PC90029
- OSTI ID:
- 420493
- Report Number(s):
- CONF-950402-; ISSN 0569-3772; TRN: 97:000006-0029
- Journal Information:
- Preprints of Papers, American Chemical Society, Division of Fuel Chemistry, Vol. 40, Issue 2; Conference: 209. American Chemical Society (ACS) national meeting, Anaheim, CA (United States), 2-6 Apr 1995; Other Information: PBD: 1995
- Country of Publication:
- United States
- Language:
- English
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