Manganese oxide-supported iron Fischer-Tropsch synthesis catalysts: physical and catalytic characterization

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:7017123

Kreitman, K M

In this study, manganese oxide-supported iron (Fe/MnO) was prepared by impregnation of powdered manganese (II) oxide with aqueous iron(III) nitrate and subjected to various calcination and reduction treatments. It was then employed as a catalyst for Fischer-Tropsch Synthesis (FTS) and its steady-state activity and selectivity behavior was observed. The FTS reaction studies were run with nearly equimolal carbon monoxide/hydrogen feed at 515 and 540 K, 7.9 and 14.8 bar pressure. Feed conversion level was kept low in order to avoid transport limitations, and was varied by adjusting space velocity. The FTS reaction rate decreased strongly with increasing conversion. Compared to unpromoted iron catalysts, the Fe/MnO catalysts were more active for the water-gas shift reaction and less selective for methane and alcohols, especially at higher conversion, lower temperature and higher pressure. The olefin selectivity was high and secondary hydrogenation was not apparent. Catalysts calcined at higher temperature exhibited stronger effects of promotion, and yielded unusually high selectivity for C/sub 2/ to C/sub 4/ hydrocarbons at low temperature and high pressure. The general conclusion is that manganese promotion or iron can promote FTS selectivity towards low molecular weight olefins, but at the expense of high carbon dioxide formation. The Fe/MnO was also physically examined using Moessbauer spectroscopy and X-ray diffraction. Iron and manganese were found to interact strongly in the calcined catalyst, though extensive phase separation occurred during reduction. The promoting effects are apparently due to partial surface coverage of iron with MnO, the extent of which is enhanced by wetter reducing conditions.

• Research Organization: Northwestern Univ., Evanston, IL (USA)
• OSTI ID: 7017123
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010408* -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
ALKENES
CALCINATION
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COHERENT SCATTERING
DECOMPOSITION
DIFFRACTION
ELEMENTS
FISCHER-TROPSCH SYNTHESIS
HYDROCARBONS
HYDROGENATION
IRON
MANGANESE COMPOUNDS
MANGANESE OXIDES
METALS
METHANATION
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PYROLYSIS
REDUCTION
SCATTERING
SPECTROSCOPY
SURFACE PROPERTIES
SYNTHESIS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
X-RAY DIFFRACTION