Stability of Co–Ce–Mn mixed-oxide catalysts for CO preferential oxidation in H2-rich gases

Guo, Qiang; Chen, Shunquan; Liu, Yuan; Wang, Yaquan

doi:10.1016/j.cej.2010.10.029

Cited by 28 publications

(6 citation statements)

References 35 publications

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“…Although most literature reports agree that cobalt remains oxidized during the COPrOx reaction, there are contradicting accounts regarding the role of Co 3+ and Co 2+ ions. In a majority of studies, Co 3 O 4 is considered as the active oxidation state of cobalt-based catalysts during COPrOx. − This is supported by recent in situ surface studies which showed that Co 3 O 4 is stable under the reducible COPrOx reaction environment. , Theoretical modeling of CO oxidation (a key step of COPrOx) over Co 3 O 4 proposed that octahedrally coordinated Co 3+ in Co 3 O 4 (111) is much more active than tetrahedrally coordinated Co 2+ for CO oxidation. − Quite to the contrary, other studies found that reduced Co 3 O 4 or cobalt monoxide (CoO) has reactivity higher than that of Co 3 O 4 for CO oxidation. − CoO is a lower valence cobalt oxide, where Co 2+ ions are octahedrally coordinated to lattice oxygen. , In addition, in situ investigations showed that the active surface state of cobalt in the reaction is nonstoichiometric Co 3 O 4– x . A recent density functional theory (DFT) study supported this idea by demonstrating that Co 2+ O h in CoO has the best oxidation activity as compared to Co 3+ O h and Co 2+ T d …”

Section: Introductionmentioning

confidence: 99%

Correlation Between Reactivity and Oxidation State of Cobalt Oxide Catalysts for CO Preferential Oxidation

et al. 2019

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Catalytic performance is known to be influenced by several factors, with the catalyst surface oxidation state being the most prominent of all. However, in the great majority of industrial heterogeneous catalytic reactions the oxidation state of the active sites is a subject of intense debate. Preferential oxidation of carbon monoxide in hydrogen-rich mixtures (COPrOx) is an important heterogeneous catalytic reaction involved in the purification of hydrogen. In the search for an economically affordable catalyst for this reaction, cobalt appears as one of the most promising materials. Therefore, it is essential to distinguish if a certain surface state of cobalt exists that favors the reaction more than the others. Here we directly compare the activity of CoO and Co3O4 phases by combining ex situ and operando analytical methods with first-principles modeling. CoO is identified as the most favored cobalt surface oxidation state for the COPrOx process, providing a critical element for the rational design of efficient and durable COPrOx catalysts.

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Section: Introductionmentioning

confidence: 99%

Correlation Between Reactivity and Oxidation State of Cobalt Oxide Catalysts for CO Preferential Oxidation

et al. 2019

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“…, 25 °C) should be associated with the formation and accumulation of carbonate-like and H 2 O/OH − species at the support interface, resulting in the blockage of active sites during the CO oxidation reaction. 31–34…”

Section: Resultsmentioning

confidence: 99%

Robust 2 nm-sized gold nanoclusters on Co₃O₄ for CO oxidation

Shi,

Li,

Cao

et al. 2023

Nanoscale Adv.

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“…The negative effect brought by H 2 O is mainly attributed to the blockage of active sites on the surface of catalyst owing to competitive adsorption, suppressing the activation of CO and O 2 . 15 While the inhibiting effect brought by CO 2 was reported to be the forming of carbonates by adsorption of CO 2 on active sites, as well as the competitive adsorption of CO and CO 2 on catalyst surface . By varying GHSV and O 2 concentration (Figure ), complete CO removal with 89.3% of selectivity can be achieved at 135°C, as well as the almost 100% of CO conversion with 94.9% of selectivity.…”

Section: Resultsmentioning

confidence: 99%

Novel Co‐Mn‐O nanosheet catalyst for CO preferential oxidation toward hydrogen purification

et al. 2014

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Co-Mn-O composite oxide nanosheet catalyst was successfully prepared using a facile urea-assisted one-step hydrothermal method in the absence of organic or organic templating reagent. Co-Mn-O nanosheet catalyst was optimized by varying hydrothermal process parameters such as molar ratio of Co-Mn to urea, hydrothermal temperature, and hydrothermal time. Various characterization techniques including scanning electron microscopy, X-ray diffraction, nitrogen adsorption, X-ray photoelectron spectroscopy, Raman spectroscopy, and H 2 temperature-programmed reduction were used to reveal the relationship between catalyst nature and catalytic performance in CO preferential oxidation (CO PROX) in excess H 2 . The developed Co-Mn-O nanosheet catalyst have demonstrated much superior catalytic performance to Co-Mn-O nanoparticle, particularly in the low temperature range, and 100% CO conversion over the developed Co-Mn-O nanosheet can be achieved in temperature range of 50 to 150 C at 10,000 mL g 21 h 21 of gas hourly space velocity in the standard feed. Furthermore, the almost complete CO removal over Co-Mn-O nanosheet at 125 C of low temperature with 94.9% selectivity can be achieved even in the simulated reformed gas. The excellent catalytic performance is ascribed to nanosheet morphology, more surface Co 31 , smaller average crystallite size, higher reducibility, and strong Co-Mn interaction. Catalytic stability investigation indicates the developed nanostructured catalyst exhibits high catalytic stability for CO PROX reaction in simulated gas. The developed Co-Mn-O nanosheet catalyst can be a potential candidate for catalytic elimination of trace CO from H 2 -rich gas for Proton exchange membrane fuel cell applications. Reaction conditions: 100 mg catalyst, GHSV 5 15,000 mL h 21 g 21 , 1.0 vol % CO, 1.0 vol % O 2 , 50 vol % H 2 , Ar balance. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] 242 Figure 8. The CO conversion (a) and O 2 selectivity to CO 2 (b) over the Co-Mn-O-ns samples prepared with diverse n Co-Mn/Urea . Reaction conditions: GHSV 5 15,000 mL h 21 g 21 , 1.0 vol % CO, 1.0 vol % O 2 , 50 vol % H 2 , Ar balance. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

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Stability of Co–Ce–Mn mixed-oxide catalysts for CO preferential oxidation in H2-rich gases

Cited by 28 publications

References 35 publications

Correlation Between Reactivity and Oxidation State of Cobalt Oxide Catalysts for CO Preferential Oxidation

Correlation Between Reactivity and Oxidation State of Cobalt Oxide Catalysts for CO Preferential Oxidation

Robust 2 nm-sized gold nanoclusters on Co₃O₄ for CO oxidation

Novel Co‐Mn‐O nanosheet catalyst for CO preferential oxidation toward hydrogen purification

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Stability of Co–Ce–Mn mixed-oxide catalysts for CO preferential oxidation in H2-rich gases

Cited by 28 publications

References 35 publications

Correlation Between Reactivity and Oxidation State of Cobalt Oxide Catalysts for CO Preferential Oxidation

Correlation Between Reactivity and Oxidation State of Cobalt Oxide Catalysts for CO Preferential Oxidation

Robust 2 nm-sized gold nanoclusters on Co3O4 for CO oxidation

Novel Co‐Mn‐O nanosheet catalyst for CO preferential oxidation toward hydrogen purification

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Product

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Robust 2 nm-sized gold nanoclusters on Co₃O₄ for CO oxidation