Enhanced activity of co-precipitated NiFeAlOx in CO2 methanation by segregation and oxidation of Fe

[Display omitted] •Reduction of NiFeAlOx catalysts leads to the formation of (γFe,Ni) alloy particles.•Aging triggers the segregation of (γFe,Ni) particles and partial oxidation of Fe.•(γFe,Ni) segregation is accompanied by an increase of intrinsic catalytic activity.•This can be explained by an add...

Full description

Saved in:
Bibliographic Details
Published in:Applied catalysis. A, General General, 2020-08, Vol.604, p.1, Article 117778
Main Authors: Burger, Thomas, Ewald, Stefan, Niederdränk, Anne, Wagner, Friedrich E., Köhler, Klaus, Hinrichsen, Olaf
Format: Article
Language:English
Subjects:
(γFe,Ni) Segregation
Activation
Activity enhancement
Aging
Carbon dioxide
Catalysts
Catalytic activity
CO2methanation
Deactivation
Fe promotion
Fe2+ surface redox properties
High temperature
Hydrothermal aging
Methanation
Nanoparticles
Nickel
NiFeAlOx catalyst
Oxidation
Structural analysis
Superposition (mathematics)
Thermodynamic equilibrium
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:[Display omitted] •Reduction of NiFeAlOx catalysts leads to the formation of (γFe,Ni) alloy particles.•Aging triggers the segregation of (γFe,Ni) particles and partial oxidation of Fe.•(γFe,Ni) segregation is accompanied by an increase of intrinsic catalytic activity.•This can be explained by an additional methanation pathway comprising Fe2+ species. Commercial application of the CO2 methanation reaction demands for the development of catalysts that feature an enhanced stability to increase catalyst lifetime. By time-resolved aging studies, we show that the improved deactivation resistance of co-precipitated NiFeAlOx catalysts compared to NiAlOx is obtained by a temporal increase of the intrinsic catalytic activity of NiFeAlOx, provoked by aging at elevated temperature and pressure in thermodynamic equilibrium. Detailed structural characterization of reduced and aged catalysts resolves that aging triggers the partial segregation of (γFe,Ni) nanoparticles initially formed during activation, accompanied by the oxidation of Fe. Thereby, the intrinsic catalytic activity increases, which can be explained by the generation of redox-active Fe2+ sites that offer an additional reaction pathway for CO2 activation. The deactivation behavior of NiFeAlOx can be described by a superimposition of activity increase related to Fe2+ site formation and decrease due to the loss of active sites by sintering processes.
ISSN:0926-860X
1873-3875
DOI:10.1016/j.apcata.2020.117778