Highly Reducible Nanostructured CeO2 for CO Oxidation

Feng, Gang; Han, Weining; Wang, Zhimiao; Li, Fang; Xue, Wei

doi:10.3390/catal8110535

Cited by 16 publications

(11 citation statements)

References 33 publications

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“…The catalytic performance of undoped CeO 2 with different morphologies in CO oxidation and other processes has been previously reported [61][62][63][64]. In short, these studies confirm that tuning the morphology of CeO 2 to increase specific surface area and selectively expose the (110) facet has a critical effect on CO oxidation activity.…”

Section: Co Oxidation Operando Drifts Experimentssupporting

confidence: 81%

Investigations of the Effect of H2 in CO Oxidation over Ceria Catalysts

et al. 2021

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The preferential CO oxidation (so-called CO-PROX) is the selective CO oxidation amid H2-rich atmospheres, a process where ceria-based materials are consolidated catalysts. This article aims to disentangle the potential CO–H2 synergism under CO-PROX conditions on the low-index ceria surfaces (111), (110) and (100). Polycrystalline ceria, nanorods and ceria nanocubes were prepared to assess the physicochemical features of the targeted surfaces. Diffuse reflectance infrared Fourier-transformed spectroscopy (DRIFTS) shows that ceria surfaces are strongly carbonated even at room temperature by the effect of CO, with their depletion related to the CO oxidation onset. Conversely, formate species formed upon OH + CO interaction appear at temperatures around 60 °C and remain adsorbed regardless the reaction degree, indicating that these species do not take part in the CO oxidation. Density functional theory calculations (DFT) reveal that ceria facets exhibit high OH coverages all along the CO-PROX reaction, whilst CO is only chemisorbed on the (110) termination. A CO oxidation mechanism that explains the early formation of carbonates on ceria and the effect of the OH coverage in the overall catalytic cycle is proposed. In short, hydroxyl groups induce surface defects on ceria that increase the COx–catalyst interaction, revealed by the CO adsorption energies and the stabilization of intermediates and readsorbed products. In addition, high OH coverages are shown to facilitate the hydrogen transfer to form less stable HCOx products, which, in the case of the (110) and (100), is key to prevent surface poisoning. Altogether, this work sheds light on the yet unclear CO–H2 interactions on ceria surfaces during CO-PROX reaction, providing valuable insights to guide the design of more efficient reactors and catalysts for this process.

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Section: Co Oxidation Operando Drifts Experimentssupporting

confidence: 81%

Investigations of the Effect of H2 in CO Oxidation over Ceria Catalysts

et al. 2021

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“…Anneggi et al proposed that {100}/{110} exposed surfaces are more reactive in photocatalysis activities, particularly on CO oxidation. This observation can be seen in many studies ( Kumar et al, 2017 ; Feng et al, 2018 ; Zhu et al, 2020 ; Zhang et al, 2021 ).…”

Section: Anion Directed Synthesis Of Metal Oxidessupporting

confidence: 60%

“…It was observed that CeO 2 nanorods showed efficient photocatalytic CO 2 reduction. Feng et al reported on highly reducible nanostructured CeO 2 for CO oxidation ( Feng et al, 2018 ). Hydrothermal synthesis reaction was carried out using Ce(NO 3 ) 3 ·6H 2 O and CeCl 3 ·7H 2 O at 110 and 160°C, respectively.…”

Section: Anion Directed Synthesis Of Metal Oxidesmentioning

confidence: 99%

Role of Anions in the Synthesis and Crystal Growth of Selected Semiconductors

2022

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The ideal methods for the preparation of semiconductors should be reproducible and possess the ability to control the morphology of the particles with monodispersity yields. Apart from that, it is also crucial to synthesize a large quantity of desired materials with good control of size, shape, morphology, crystallinity, composition, and surface chemistry at a reasonably low production cost. Metal oxides and chalcogenides with various morphologies and crystal structures have been obtained using different anion metal precursors (and/or different sulfur sources for chalcogenides in particular) through typical synthesis methods. Generally, spherical particles are obtained as it is thermodynamically favorable. However, by changing the anion precursor salts, the morphology of a semiconductor is influenced. Therefore, precursors having different anions show some effects on the final forms of a semiconductor. This review compiled and discussed the effects of anions (NO3−, Cl−, SO42-, CH3COO−, CH(CH3)O−, etc.) and different sources of S2- on the morphology and crystal structure of selected metal oxides and chalcogenides respectively.

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“…Mg(OH) 2 is known to be an almost non-reducible metal oxide [14,53], which can explain the fact that noteworthy signals representing H 2 consumption were not observed in the 3AuM sample. In contrast, CeO 2 is known to be a highly reducible metal oxide [14,54], and therefore the 3AuC sample exhibited a peak at a low reduction temperature of ~226-273 • C [55]. Interestingly, the shape of the H 2 -TPR profile of 3AuCM was similar to that of 3AuC, indicating that the reducible natures of 3AuCM and 3AuC are comparable.…”

Section: Materials Characterizationmentioning

confidence: 95%

A Multifunctional Au/CeO2-Mg(OH)2 Catalyst for One-Pot Aerobic Oxidative Esterification of Aldehydes with Alcohols to Alkyl Esters

et al. 2021

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Au nanoparticles bound to crystalline CeO2 nanograins that were dispersed on the nanoplate-like Mg(OH)2, denoted as Au/CeO2-Mg(OH)2, were developed as the highly active and selective multifunctional heterogeneous catalyst for direct oxidative esterification of aldehydes with alcohols to produce alkyl esters under base-free aerobic conditions using oxygen or air as the green oxidants. Au/CeO2-Mg(OH)2 converted 93.3% of methacrylaldehyde (MACR) to methyl methacrylate (MMA, monomer of poly(methyl methacrylate)) with 98.2% selectivity within 1 h, and was repeatedly used over eight recycle runs without regeneration. The catalyst was extensively applied to other aldehydes and alcohols to produce desirable alkyl esters. Comprehensive characterization analyses revealed that the strong metal–support interaction (SMSI) among the three catalytic components (Au, CeO2, and Mg(OH)2), and the proximity and strong contact between Au/CeO2 and the Mg(OH)2 surface were prominent factors that accelerated the reaction toward a desirable oxidative esterification pathway. During the reaction, MACR was adsorbed on the surface of CeO2-Mg(OH)2, upon which methanol was simultaneously activated for esterifying the adsorbed MACR. Hemiacetal-form intermediate species were subsequently produced and oxidized to MMA on the surface of the electron-rich Au nanoparticles bound to partially reduced CeO2−x with electron-donating properties. The present study provides new insights into the design of SMSI-induced supported-metal-nanoparticles for the development of novel, multifunctional, and heterogeneous catalysts.

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Highly Reducible Nanostructured CeO2 for CO Oxidation

Cited by 16 publications

References 33 publications

Investigations of the Effect of H2 in CO Oxidation over Ceria Catalysts

Investigations of the Effect of H2 in CO Oxidation over Ceria Catalysts

Role of Anions in the Synthesis and Crystal Growth of Selected Semiconductors

A Multifunctional Au/CeO2-Mg(OH)2 Catalyst for One-Pot Aerobic Oxidative Esterification of Aldehydes with Alcohols to Alkyl Esters

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