Reduction of CuO-containing catalysts, CuO: II, XRD and XPS

Boyce, A. L.; Graville, S. R.; Sermon, Paul A.; Vong, M. S. W.

doi:10.1007/bf02068377

Cited by 12 publications

(7 citation statements)

References 5 publications

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“…The choice of CO as a probe molecule for Cu ions is implied from the existence of a characteristic carbonyl frequency shift, which depends strictly on the copper coordination environment, as well as the oxidation state [ 14 , 15 , 16 ]. In the case of Cu 2+ cations, the CO-IR analysis is insufficient, thus complementary techniques such as Electron Paramagnetic Resonance (EPR) [ 17 , 18 , 19 ], X-ray photoelectron spectroscopy (XPS) [ 20 , 21 , 22 ] and temperature-programmed reduction (TPR) [ 20 , 23 , 24 , 25 , 26 ], as well as IR studies of NO sorption, are needed to receive a detailed characterization of the oxidation state and properties of Cu in zeolites under various red-ox conditions, e.g., [ 27 , 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

et al. 2020

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The process of reduction (by hydrogen and ethanol) and oxidation (by oxygen and NO) of Cu sites in dealuminated faujasite-type zeolites (of Si/Al = 31) was studied by infrared (IR) spectroscopy with CO (for Cu+) and NO (for Cu2+) as probe molecules. Two zeolites were studied: one of them contained mostly Cu+exch., whereas another one contained mostly Cu2+ and Cu+ox. The susceptibility of various forms of Cu for reduction were investigated. IR experiments of CO sorption evidenced that Cu+ox. was more prone for the reduction than Cu+exch. According to NO sorption studies, Cu2+exch. was reduced in the first order before Cu2+ox. Ethanol reduced mostly Cu2+ and, also, some amounts of Cu+. The treatment with oxygen caused the oxidation of Cu+ (both Cu+exch. and Cu+ox.) to Cu2+. The adsorption of NO at 190K produced Cu+(NO)2 dinitrosyls, but heating to room temperature transformed dinitrosyls to mononitrosyls and increased the Cu2+ content.

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Section: Introductionmentioning

confidence: 99%

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

et al. 2020

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“…XPS was employed to acquire the information about the valence state of Cu and Ce species. The Cu 2p profile contained the principal doublet peaks (Cu 2p 3/2 and Cu 2p 1/2 ) and the corresponding satellite peaks caused by charge transfer. ,,− In Figure a, there was a peak shift of Cu 2p 3/2 in the catalysts from Cu1Ce1 (933.0 eV) to Cu20Ce1 (934.0 eV). Since the principal Cu 2p 3/2 peak at 934.0 eV was characterized as typical Cu 2+ and the red shift of this peak at 933.0 eV were assigned to negative charged Cu + , ,, the Cu 2p 3/2 peak could be divided into two parts.…”

Section: Results and Discussionmentioning

confidence: 97%

Unraveling the Change in Multiple Cu Species Present in CuO/CeO₂ over the Preferential CO Oxidation Reaction

Chen

Xia

Lao

et al. 2021

Ind. Eng. Chem. Res.

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CuO/CeO2 with strong metal–support interaction was considered to be a highly efficient catalyst in the PROX (preferential CO oxidation) reaction. Multiple Cu species from this interaction were believed to play a key role in catalytic activity. However, due to the complex chemical properties of copper, there was still controversy about the nature of active sites in the PROX reaction. In this work, the types and proportion of Cu species (Cu–[O] x –Ce, amorphous CuO x , and aggregated CuO x ) could be well-controlled since CuO was loaded on surface-modified CeO2. Their properties were studied in detail through a series of characterizations. The Cu–[O] x –Ce structure was found to be the most favorable for preferential CO oxidation. While the amorphous CuO x cluster could facilitate CO oxidation, it would greatly reduce the selectivity. The aggregated CuO x caused by excessive CuO only had activity at high temperature, resulting in an upper limit of the CuO loading amount. The proportion of these Cu species varied with the CuO loading amount, and the catalytic performance was the synergetic result of all Cu species.

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“…The broad diffraction peaks imply the existence of a generally poor crystal spinel‐type phase mixed with several oxides in the catalyst. Some characteristic diffraction peaks can be identified for CuO at 2 θ =35.4 and 38.6°, Cu at 2 θ =43.4 and 50.5°, Cu 2 (OH) 2 CO 3 at 2 θ =15.4 and 22.5°, (Cu,Zn) 2 CO 3 (OH) 2 at 2 θ =35.4°, and ZnO at 2 θ =36.4° . No clear diffraction peak can be assigned to Al 2 O 3 because of its homogeneous dispersion in the catalyst system …”

Section: Resultsmentioning

confidence: 97%

“…Some characteristic diffraction peaks can be identified for CuO at 2 q = 35.4 and 38.68,C ua t2q = 43.4 and 50.58,C u 2 (OH) 2 CO 3 at 2 q = 15.4 and 22.58, (Cu,Zn) 2 CO 3 (OH) 2 at 2 q = 35.48,a nd ZnO at 2 q = 36.48. [32,33] No clear diffraction peak can be assigned to Al 2 O 3 because of its homogeneous dispersion in the catalyst system. [10,34] Ther oleo fZ nO is an essential component of the Cubased catalyst, which segregates the Cu species for CuO/ ZnO/Al 2 O 3 .T he synergy effect between ZnO and CuO can improve the overall thermal stability of the catalyst.…”

Section: Microstructural Analysismentioning

confidence: 99%

Process Intensification of the Hydrogen Production Reaction Using a Carbon Membrane Reactor: Kinetics Analysis

et al. 2017

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Plate carbon membranes were fabricated and coupled into a membrane reactor to intensify the steam reforming of methanol (SRM). The homemade Cu‐based catalyst and carbon membranes were characterized by using thermogravimetric analysis, X‐ray diffraction, N2 adsorption, and gas permeation. The effects of the reaction temperature, reactor type, and carbon membranes on the methanol conversion and hydrogen yield were investigated. The results show that the coupling of carbon membranes in the reactor improves the methanol conversion significantly. In addition, both the methanol conversion and reaction rate increase, and the hydrogen yield first decreases then increases as the reaction temperature was elevated from 220 to 300 °C. This indicates that both thermodynamic and kinetic factors contribute to the intensification of SRM in the carbon membrane reactor.

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Reduction of CuO-containing catalysts, CuO: II, XRD and XPS

Cited by 12 publications

References 5 publications

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

Unraveling the Change in Multiple Cu Species Present in CuO/CeO₂ over the Preferential CO Oxidation Reaction

Process Intensification of the Hydrogen Production Reaction Using a Carbon Membrane Reactor: Kinetics Analysis

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Reduction of CuO-containing catalysts, CuO: II, XRD and XPS

Cited by 12 publications

References 5 publications

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

Unraveling the Change in Multiple Cu Species Present in CuO/CeO2 over the Preferential CO Oxidation Reaction

Process Intensification of the Hydrogen Production Reaction Using a Carbon Membrane Reactor: Kinetics Analysis

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Unraveling the Change in Multiple Cu Species Present in CuO/CeO₂ over the Preferential CO Oxidation Reaction