Activation studies with a precipitated iron catalyst for Fischer-Tropsch synthesis. II. Reaction studies

Journal Article · Fri Sep 01 04:00:00 EDT 1995 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1995.1218· OSTI ID:486296

Bukur, D B; Nowicki, L; Manne, R K; Lang, Xiaosu ^[1]

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1. Texas A&M Univ., College Station, TX (United States)

Effects of pretreatment conditions on catalyst performance (activity, selectivity, and stability with time) during Fischer-Tropsch (FT) synthesis were studied in a fixed-bed reactor using a commercial precipitated iron catalyst (100 Fe/5 Cu/4.2K/25 SiO{sub 2} on a mass basis). The catalyst activity increased slightly with time-on-stream after hydrogen reductions, which was accompanied with conversion of metallic iron and part of iron oxides to {epsilon}{prime}-carbide ({epsilon}{prime}-Fe{sub 22}C). Initial activity of the H{sub 2}-reduced catalyst at 280{degrees}C for 8 or 24 h was markedly lower than that obtained in other tests. This is attributed to slow carburization of large oxide particles and partial poisoning of catalyst sites by migration of sulfur from the bulk to the surface of the catalyst during the reduction. Pretreatments with carbon monoxide and syngas resulted in partial conversion of Fe{sub 2}O{sub 3} to {chi}-carbide ({chi}-Fe{sub 5}C{sub 2}). During FT synthesis the CO- and the syngas-pretreated catalyst deactivated slowly with time-on-stream, due to partial conversion of {chi}-carbide to less active iron oxide phases and buildup of carbonaceous deposits which block the active sites. The hydrogen-reduced catalyst at 280{degrees}C, for 1-24h, produced more methane and gaseous hydrocarbons than the CO- or the syngas-pretreated catalyst and favored secondary reactions (1-olefin hydrogenation, isomerization, and readsorption). 41 refs., 5 figs., 2 tabs.

• DOE Contract Number: AC22-89PC89868
• OSTI ID: 486296
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 155; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CARBON MONOXIDE
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL ACTIVATION
FISCHER-TROPSCH SYNTHESIS
IRON
SYNTHESIS GAS