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

Ariëns, Maxim; Chlan, V.; Novák, P.; Water, Leon G. A. van de; Dugulan, A. Iulian; Brück, E.; Hensen, Emiel J. M.

doi:10.1016/j.apcatb.2021.120465

Cited by 20 publications

(27 citation statements)

References 36 publications

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“…The Cr 2p XPS spectra can be deconvoluted into three peaks (Figure 4b), revealing that the chromium dopants consist of Cr 6+ and Cr 3+ species. The green peak at 576.9 eV belongs to Cr 3+ species, and the other two peaks are assigned to Cr 6+ species [32] …”

Section: Resultsmentioning

confidence: 99%

“…Figure 3b displays the H 2 ‐TPR profiles of the different nanocomposite catalysts in the range of 50–500 °C and corresponding peak temperatures are listed in Table 2. The CrCe catalyst exhibited only a symmetrical peak at ∼336 °C, assigned to the reduction of surface “−Cr VI −[O x ]−Ce−” species to “−Cr III −[O x ]−Ce−” [32] . The TPR profile of the CuCe solid solution could be deconvoluted into two main peaks at ∼176 °C and 186 °C, which are attributed to the reduction of surface “−Cu II/I −[O x ]−Ce−” species to metallic copper (Cu 0 ) [33,34] …”

Section: Resultsmentioning

confidence: 99%

“…The CrCe catalyst exhibited only a symmetrical peak at ~336 °C, assigned to the reduction of surface "À Cr VI À [O x ]À CeÀ " species to "À Cr III À [O x ]À CeÀ ". [32] The TPR profile of the CuCe solid solution could be deconvoluted into two main peaks at ~176 °C and 186 °C, which are attributed to the reduction of surface "À Cu II/ I À [O x ]À CeÀ " species to metallic copper (Cu 0 ). [33,34] The TPR profile of the ternary CuCrCe catalyst is composed of peaks at ~142 °C, 173 °C, and 182 °C, which are attributed to the reduction of "À Cr VI À [O x ]À Cu II À [O x ]À CeÀ " species to "À Cr III À [O x ]À CeÀ " and metallic copper.…”

Section: Chemcatchemmentioning

confidence: 99%

“…The green peak at 576.9 eV belongs to Cr 3 + species, and the other two peaks are assigned to Cr 6 + species. [32] The Cu 2p spectra (Figure 4c) reveal that the copper dopants embrace Cu 2 + and Cu + species, as evidenced by the observation of the two typical peaks at 934.8 eV and 933.4 eV. [21,25] Interestingly, the low coordinated Cu + species was not detected in the CuCrCe catalysts, due to the coupling of the redox cycles of Cr VI /Cr III and Cu II /Cu I , i. e. the Cu + species can be easily oxidized to Cu 2 + by Cr 6 + species consistent with the results of H 2 -TPR (Figure 2b).…”

Section: Chemcatchemmentioning

confidence: 99%

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Ternary CuCrCeO_x Solid Solution Enhances N₂‐Selectivity in the NO Reduction with CO in the Presence of Water and Oxygen

et al. 2022

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Co‐doping of ceria with Cu and Cr forming a ternary CuCrCeOx solid solution enhances N2‐selectivity as well as NO and CO conversions compared to the corresponding singly doped ceria, CuCeOx and CrCeOx, and pristine ceria, in the absence as well as presence of water and oxygen. The comparative study of these solid‐solution catalysts indicates that the doping of ceria results in the coupling of different transition metal redox cycles, which has a strong effect on the surface population of oxygen vacancies. The temperature required to reach 95 % N2‐selectivity is shown to be nearly linearly correlated to the concentration of oxygen vacancy defects. The oxygen defect population is highest for the ternary CuCrCeOx solid solution, which exhibits the best catalytic performance, reaching 100 % N2‐selectivity at around 100 °C. Three redox cycles (CrVI/CrIII, CuII/CuI, and CeIV/CeIII) have been identified in this catalyst leading to a synergistic effect. The ternary CuCrCeOx catalyst exhibits good water tolerance and long‐term stability while the SO2 tolerance is limited due to selective blocking of the active surface oxygen defects forming SO32− species, resulting in catalyst deactivation.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Chemcatchemmentioning

confidence: 99%

Section: Chemcatchemmentioning

confidence: 99%

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Ternary CuCrCeO_x Solid Solution Enhances N₂‐Selectivity in the NO Reduction with CO in the Presence of Water and Oxygen

et al. 2022

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“…Some characterization data of the HM, Cr-HM, and CrCu-HM reference catalysts were published elsewhere. 5,6 Characterization. X-ray powder diffraction (XRD) patterns were recorded on a PANalytical X'pert pro diffractometer using Cu Kα radiation.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

et al. 2022

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A set of doped iron oxides (chromium, aluminum, gallium, indium, manganese, zinc, niobium) were prepared by a one-step coprecipitation/calcination approach evaluated for their WGS activity under industrially relevant conditions and characterized in detail. The WGS activity after ageing the doped catalyst for 4 days at 25 bar follows the order chromium ≈ aluminum > gallium > indium > manganese > zinc > niobium for copper-codoped catalysts. The activated catalysts predominantly consist of magnetite, irrespective of the dopant. Mössbauer spectra of aged catalysts showed that aluminum and zinc occupy both tetrahedral and octahedral sites of magnetite, while chromium, gallium, indium, manganese, and niobium preferentially substitute octahedral iron. The incorporation of trivalent metal ions of similar size to octahedral Fe3+ (i.e., chromium, aluminum, gallium) results in moderate to high CO conversion, irrespective of incorporation in tetrahedral or octahedral sites. The substitution of Fe2+ with Mn2+ results in an increased Fe3+/Fe2+ ratio. Incorporation of Zn2+ in tetrahedral sites (replacing Fe3+ ions) leads to a complex structure where the charge balance is compensated from the octahedral sites. Separate dopant metal oxide phases were observed in indium- and niobium-doped catalysts. XPS shows that copper is present as a separate phase in activated copper-codoped catalysts. Aluminum is identified as the most promising promoter for substituting chromium in commercial high-temperature WGS catalysts on the basis of their similar high CO conversion although incorporation of these dopants into the magnetite structure differed substantially.

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Cr and CeO2 promoted Ni/SBA-15 framework for hydrogen production by steam reforming of glycerol

Abrokwah,

Ntow,

Jennings

et al. 2023

Environ Sci Pollut Res

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Ni/SBA-15 meso-structured catalysts modi ed with Chromium and CeO 2 (Ni-Cr-CeO 2 /SBA-15) were utilized to produce hydrogen from glycerol steam reforming (GSR). The catalysts were synthesized by a one-pot hydrothermal process and extensively characterized by analytical techniques such as N 2 adsorption-desorption (BET), H 2 -temperature programmed reduction (H 2 -TPR), powder X-ray diffraction (PXRD), Inductively coupled plasma-optical emission spectrometry (ICP-OES), and Transmission electron microscopy (TEM). Overall, the Ni-based catalysts exhibited higher glycerol conversion − 12Ni-SBA-15-99.9%, 12Ni3CeO 2 -SBA-15-89.4% and 8Ni4Cr3CeO 2 -SBA-15-99.7%. Monometallic 12Ni/SBA-15 performed exceptionally well, while 12Cr/SBA-15 performed poorly with the highest 71.48% CO selectivity. For shortterm GSR reactions, CeO 2 addition to 12Ni/SBA-15 did not have any effect, whereas Cr addition resulted in 32% decrease in H 2 selectivity. The long-term stability studies of 12Ni-SBA-15 showed H 2 selectivity of ~ 64% and ~ 98% glycerol conversion. However, its activity was short-lived. After 20-30hrs, the H 2 selectivity and conversion dropped precipitously to 40%. The doping of mesoporous Ni/SBA-15 with Cr and CeO 2 remarkably enhanced the long-term stability of the catalyst for 12Ni3CeO 2 -SBA-15, and 8Ni4Cr3CeO 2 -SBA-15 catalyst with ~ 58% H 2 selectivity and ~ 100% conversion for the entire 60hrs. Nonetheless, Cr and CeO 2 seem to improve the shelf-life of Ni-SBA-15 via different mechanistic pathways. CeO 2 mitigated Ni poisoning through coke oxidation whereas Cr bolstered the catalyst stability via maintaining a wellde ned pore size and structural integrity of the heterogeneous framework, thereby restricting structural collapse, and hence reducing sintering of the Ni active sites during the long-term 60hrs continuous reaction.

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

Cited by 20 publications

References 36 publications

Ternary CuCrCeO_x Solid Solution Enhances N₂‐Selectivity in the NO Reduction with CO in the Presence of Water and Oxygen

Ternary CuCrCeO_x Solid Solution Enhances N₂‐Selectivity in the NO Reduction with CO in the Presence of Water and Oxygen

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

Cr and CeO2 promoted Ni/SBA-15 framework for hydrogen production by steam reforming of glycerol

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

Cited by 20 publications

References 36 publications

Ternary CuCrCeOx Solid Solution Enhances N2‐Selectivity in the NO Reduction with CO in the Presence of Water and Oxygen

Ternary CuCrCeOx Solid Solution Enhances N2‐Selectivity in the NO Reduction with CO in the Presence of Water and Oxygen

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

Cr and CeO2 promoted Ni/SBA-15 framework for hydrogen production by steam reforming of glycerol

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Product

Resources

About

Ternary CuCrCeO_x Solid Solution Enhances N₂‐Selectivity in the NO Reduction with CO in the Presence of Water and Oxygen

Ternary CuCrCeO_x Solid Solution Enhances N₂‐Selectivity in the NO Reduction with CO in the Presence of Water and Oxygen