Promotion of Fe3O4/Cr2O3 high temperature water gas shift catalyst

Rhodes, Colin; Williams, B. Peter; King, Frank D.; Hutchings, Graham J.

doi:10.1016/s1566-7367(02)00156-5

Cited by 155 publications

(81 citation statements)

References 16 publications

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“…Figuera and co-workers [213; 214] showed that annealing the (100) is extensively utilized, most data appears to favour the redox mechanism. Interestingly, Rhodes et al [441] showed that WGS activity is enhanced by the addition of various promotor metals, and concluded that strengthening CO adsorption was key to improving catalyst activity.…”

Section: Oxygen (O 2 )mentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

501

463

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The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe 3 O 4 ), maghemite (γ-Fe 2 O 3 ), hematite (α-Fe 2 O 3 ), and wüstite (Fe 1-x O) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe 3 O 4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment, and because it is an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed.The best understood iron oxide surface at present is probably Fe 3 O 4 (100); the structure is known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Fe oct -O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10 Such straightforward preparation of a monophase termination is generally not the case for other iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch-Cohen defects in Fe (0001) is the most studied hematite surface, but 2 difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called "bi-phase" structure is formed, which eventually transforms to a Fe 3 O 4 (111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe 1-x O and α-Fe 2 O 3 (0001) islands was recently challenged and a new structure based on a thin film of Fe 3 O 4 (111) on α-Fe 2 O 3 (0001) was proposed. The merits of the compet...

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Section: Oxygen (O 2 )mentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

501

463

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“…1 For example, potential promotional roles of Co, Bu, Ag, Ba, Ce for Fe-Cr-O catalysts were examined. [2][3][4][5][6][7][8][9][10] Fe-Cu-Al-O catalysts 2,3,9 reported recently exhibit a comparable catalytic performance to Fe-Cr-O and other Fe-based catalysts. 8 Cu is considered as a promoter for the high temperature WGS catalysts, Fe-Cu-Al-O.…”

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The role of copper in catalytic performance of a Fe–Cu–Al–O catalyst for water gas shift reaction

Wang

Zhang

et al. 2013

Chem. Commun.

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A Fe-Cu-Al-O water gas shift catalyst with a Fe : Cu atomic ratio of 4 : 1 upon pretreatment at 350 8C in H 2 exhibits a conversion higher than a physical mixture of Fe-Al-O and Cu-Al-O by B40% over a temperature range of 300 8C-450 8C. In situ ambient pressure X-ray photoelectron spectroscopy studies suggest that the surface region of Fe-Cu-Al-O was restructured into a double-layer structure consisting of a surface layer of

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“…In the first step, carried out in the 310-450 ∘ C range with the use of Fe 3 O 4 /Cr 2 O 3 catalyst, the CO concentration is reduced from 10 to 3 vol%. In the second step, carried out in the 180-250 ∘ C range, the CO content is further reduced to the low level of 500 ppm using Cu/ZnO/Al 2 O 3 catalysts [26].…”

Section: Water-gas Shift Preferential Oxidation and Methanationmentioning

confidence: 99%

Hydrogen Production Technologies: Current State and Future Developments

Kalamaras

Efstathiou

2013

Conference Papers in Energy

357

177

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Hydrogen (H2) is currently used mainly in the chemical industry for the production of ammonia and methanol. Nevertheless, in the near future, hydrogen is expected to become a significant fuel that will largely contribute to the quality of atmospheric air. Hydrogen as a chemical element (H) is the most widespread one on the earth and as molecular dihydrogen (H2) can be obtained from a number of sources both renewable and nonrenewable by various processes. Hydrogen global production has so far been dominated by fossil fuels, with the most significant contemporary technologies being the steam reforming of hydrocarbons (e.g., natural gas). Pure hydrogen is also produced by electrolysis of water, an energy demanding process. This work reviews the current technologies used for hydrogen (H2) production from both fossil and renewable biomass resources, including reforming (steam, partial oxidation, autothermal, plasma, and aqueous phase) and pyrolysis. In addition, other methods for generating hydrogen (e.g., electrolysis of water) and purification methods, such as desulfurization and water-gas shift reactions are discussed.

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Promotion of Fe3O4/Cr2O3 high temperature water gas shift catalyst

Cited by 155 publications

References 16 publications

Iron oxide surfaces

Iron oxide surfaces

The role of copper in catalytic performance of a Fe–Cu–Al–O catalyst for water gas shift reaction

Hydrogen Production Technologies: Current State and Future Developments

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