The role of chromium in iron-based high-temperature water-gas shift catalysts under industrial conditions

Journal article (2021)

Authors

M.I. Ariëns Eindhoven University of Technology, RST/Fundamental Aspects of Materials and Energy - AS
V. Chlan Charles University
P Novak Institute of Physics of the Academy of Sciences of the Czech Republic
L. G.A. van de Water Johnson Matthey Technology Center
A.I. Dugulan RID/TS/Instrumenten groep , RST/Fundamental Aspects of Materials and Energy - AS
E.H. Brück RST/Fundamental Aspects of Materials and Energy - AS
Emiel J.M. Hensen Eindhoven University of Technology
Research Group
RST/Fundamental Aspects of Materials and Energy (AS) (TU Delft)
Copyright: © 2021 M.I. Ariëns, V. Chlan, P. Novák, L. G.A. van de Water, A.I. Dugulan, E.H. Brück, E. J.M. Hensen
DOI
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https://doi.org/10.1016/j.apcatb.2021.120465
Mössbauer spectroscopy Iron oxide Promotion Chromium Water-gas shift reaction
More Info
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Published Date

2021

Language

English

Faculty

Applied Sciences

Department

RST/Radiation, Science and Technology

Research Group

RST/Fundamental Aspects of Materials and Energy

Abstract

Chromium promotion of iron oxide based water-gas shift (WGS) catalysts prepared via co-precipitation/calcination was investigated. Mössbauer spectroscopy and XRD evidence that chromium is incorporated in the calcined hematite (α-Fe2O3) precursor irrespective of the doping level (0−12 wt.%). CO-TPR shows chromium delays the reduction of hematite and the active magnetite (Fe3O4) phase. WGS activity was evaluated under realistic conditions for 4 days. Enhanced CO conversion was observed with increased chromium doping. Mössbauer spectra indicate that chromium incorporates into octahedral sites of magnetite and prevents reduction of Fe3+ to Fe2+ during formation of the active phase, leading to an increased Fe3+/Fe2+ ratio in octahedral sites. The higher Fe3+/Fe2+ ratio did not affect the high CO conversion associated with the structural stabilization mechanism of Cr-doping. Interpretation of the Mössbauer spectra was supported by computational modelling of various chromium and vacancy-doped magnetite structures. The bulk structure of an in situ prepared chromium-doped high-temperature WGS catalyst is best described as a partially oxidized chromium-doped magnetite phase. No surface effects of Cr-doping were found.