Hydrogenation of carbon monoxide over Raney iron-manganese catalysts
The Raney Fe and Raney Fe-Mn catalysts were prepared by leaching the aluminum from Al-Fe (50/50 wt%) and Al-Fe-Mn (59/38/3 wt%) alloys with an aqueous solution of sodium hydroxide (2 to 20 wt%) in the temperature range of 298 to 363 K by two different leaching modes, caustic or alloy addition. The major phase in all the Raney Fe and Raney Fe-Mn catalysts was found to be ..cap alpha..-Fe from X-ray diffraction study. The BET surface area of the Raney Fe catalyst ranged from 26 to 54 m/sup 2//g, while it ranged from 64 to 116 m/sup 2//g for Raney Fe-Mn catalysts depending on the preparation conditions. The crystallite size of the ..cap alpha..-Fe in the Raney catalysts, estimated by X-ray line broadening, ranged from 70 to 250 Angstrom and it increased with increasing leaching temperature. The optimum reduction temperature was found to be 648 K for the Raney catalysts (Fe and Fe-Mn) and 673 K for the precipitated catalysts (Fe and Fe-Mn) from thermogravimetric analyses. The Raney and precipitated catalysts, reduced in-situ in flowing hydrogen, were evaluated for the hydrogenation of carbon monoxide in a high-pressure fixed-bed reactor at the following standard reaction conditions: pressure = 1465 KPa, space velocity = 3.0 cm/sup 3/g/sup -1/s/sup -1/, H/sub 2//CO = 2.0, and reaction temperature of 423 to 473 K. The Raney Fe and Raney Fe-Mn catalysts were 2 to 4 times more active in terms of carbon monoxide conversion than the corresponding precipitated Fe and Fe-Mn catalysts, respectively, at the standard reaction conditions. The activation energy ranged from 96 to 139 KJ/mol depending on different catalysts.
- OSTI ID:
- 7066066
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
10 SYNTHETIC FUELS
ALKALI METAL COMPOUNDS
ALLOYS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
DISSOLUTION
HYDROGEN COMPOUNDS
HYDROXIDES
IRON ALLOYS
LEACHING
MANGANESE ALLOYS
METHANATION
OXIDES
OXYGEN COMPOUNDS
SEPARATION PROCESSES
SODIUM COMPOUNDS
SODIUM HYDROXIDES
TEMPERATURE DEPENDENCE