Iron-induced deactivation of supported nickel methanation catalysts. Final report
A high pressure vessel has been tested and shown to be effective for the simultaneous collection of methanation kinetics and in situ Moessbauer spectra. Using this cell, the deactivation of an alumina-supported nickel catalyst (Ni/Al/sub 2/O/sub 3/) was studied before, during and after the dosing of Fe(CO)/sub 5/ onto the sample under methanation reaction conditions. This iron-induced deactivation was initiated by passing CO at high pressure (4 MPa) over an iron catalyst (at 473/sup 0/K) for the in situ production of Fe(CO)/sub 5/, followed by mixing the CO with H/sub 2/ and passing this synthesis gas mixture over the Ni/Al/sub 2/O/sub 3/ catalyst at temperatures and pressures near 620/sup 0/K and 0.2 MPa. The Moessbauer spectra collected under these methanation reaction conditions (with H/sub 2//CO partial pressure ratios near 10) showed the iron on Ni/Al/sub 2/O/sub 3/ to be present as an iron carbide. Treatment in hydrogen of the iron-deactivated catalyst at 620/sup 0/K gave rise to a Moessbauer spectrum characteristic of metallic iron, indicating that the iron on Ni/Al/sub 2/O/sub 3/ is not in direct contact with nickel (i.e. an FeNi alloy is not formed nor does iron form a monolayer coating over nickel crystallites). Furthermore, for Fe/Ni atomic ratios of approximately 0.03, the methanation kinetics over an iron-deactivated Ni/Al/sub 2/O/sub 3/ catalyst approached those characteristic of iron alone. This sensitivity of the methanation kinetics to small amounts of iron, combined with the observation that iron and nickel are not in direct contact, indicates that iron deactivates supported nickel catalysts by depositing in and blocking the pore mouths of the support.
- Research Organization:
- Wisconsin Univ., Madison (USA). Dept. of Chemical Engineering
- DOE Contract Number:
- FG21-78ET12248
- OSTI ID:
- 6528865
- Report Number(s):
- DOE/ET/12248-T3; ON: DE81023795
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010404* -- Coal
Lignite
& Peat-- Gasification
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COAL GASIFICATION
DATA
DEACTIVATION
ELEMENTS
EXPERIMENTAL DATA
GASIFICATION
INFORMATION
IRON
IRON COMPOUNDS
METALS
METHANATION
MOESSBAUER EFFECT
NICKEL
NUMERICAL DATA
SYNTHESIS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS