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

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1556
Author(s):  
Arantxa Davó-Quiñonero ◽  
Sergio López-Rodríguez ◽  
Cristian Chaparro-Garnica ◽  
Iris Martín-García ◽  
Esther Bailón-García ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Surface Defects ◽  
Co Adsorption ◽  
Oxidation Mechanism ◽  
Density Functional Theory Calculations ◽  
Hydroxyl Groups ◽  
Selective Co Oxidation ◽  
Physicochemical Features

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.

scholarly journals Unique structure of active platinum-bismuth site for oxidation of carbon monoxide

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bing Nan ◽  
Qiang Fu ◽  
Jing Yu ◽  
Miao Shu ◽  
Lu-Lu Zhou ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Low Temperature ◽  
Co Oxidation ◽  
Density Functional ◽  
Technology Development ◽  
Co Adsorption ◽  
Combustion Engines ◽  
Advanced Combustion ◽  
Surface Metal ◽  
Bismuth Cluster

AbstractAs the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant is added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~50 °C) with a high CO2 production rate of 487 μmolCO2·gPt−1·s−1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt−O−Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a unique and general approach towards design of potential excellent performance catalysts for redox reaction.

scholarly journals Pd/Pt embedded CN monolayers as efficient catalysts for CO oxidation

2019 ◽  
Vol 21 (46) ◽  
pp. 25743-25748
Author(s):  
Yong-Chao Rao ◽  
Xiang-Mei Duan
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Density Functional ◽  
Carbon Nitride ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Functional Theory ◽  
Spin Polarized ◽  
Planar Carbon

The catalytic performance of Pd/Pt embedded planar carbon nitride for CO oxidation has been investigated via spin-polarized density functional theory calculations.

Binuclear O2 activation and hydrogen transfer mechanism for aerobic oxidation of alcohols

2020 ◽  
Vol 10 (7) ◽  
pp. 2183-2192
Author(s):  
Zhiyun Hu ◽  
Hongyu Ge ◽  
Xinzheng Yang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Aerobic Oxidation ◽  
Density Functional Theory Calculations ◽  
Transfer Mechanism ◽  
Functional Theory ◽  
O2 Activation ◽  
Oxidation Of Alcohols

Density functional theory calculations reveal a binuclear O2 activation and hydrogen transfer mechanism with spin-crossovers for aerobic oxidation of alcohols.

CO oxidation by MoS2-supported Au19 nanoparticles: effects of vacancy formation and tensile strain

2016 ◽  
Vol 18 (19) ◽  
pp. 13232-13238 ◽  
Author(s):  
Soonho Kwon ◽  
Kihyun Shin ◽  
Kihoon Bang ◽  
Hyun You Kim ◽  
Hyuck Mo Lee
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Catalytic Oxidation ◽  
Density Functional ◽  
Tensile Strain ◽  
Density Functional Theory Calculations ◽  
Vacancy Formation ◽  
Oxidation Of Co ◽  
Functional Theory ◽  
Catalytic Oxidation Of Co

The mechanism of the catalytic oxidation of CO activated by MoS2-supported Au19 nanoparticles (NPs) was studied using density functional theory calculations.

The interplay between structural perfectness and CO oxidation catalysis on aluminum, phosphorous and silicon complexes of corroles

2019 ◽  
Vol 21 (14) ◽  
pp. 7661-7674 ◽  
Author(s):  
Afshan Mohajeri ◽  
Nasim Hassani
Keyword(s):  
Density Functional Theory ◽  
Carbon Monoxide ◽  
Co Oxidation ◽  
Catalytic Oxidation ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Oxidation Catalysis ◽  
Functional Theory ◽  
Oxidation Of Carbon Monoxide

Catalytic oxidation of carbon monoxide on perfect and defective structures of corrole complexes with aluminum, phosphorous and silicon have been investigated by performing density functional theory calculations.

scholarly journals Novel structure of active platinum-bismuth site for oxidation of carbon monoxide

2020 ◽  
Author(s):  
Bing Nan ◽  
Qiang Fu ◽  
Miao Shu ◽  
Lulu Zhou ◽  
Wei-Wei Wang ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Low Temperature ◽  
Co Oxidation ◽  
Density Functional ◽  
Technology Development ◽  
Co Adsorption ◽  
Advanced Combustion ◽  
Novel Structure ◽  
Surface Metal ◽  
Bismuth Cluster

Abstract As the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~ 50 °C) with a high CO2 production rate of 487 µmolCO2·gPt−1·s− 1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt−O−Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a novel and general approach towards design of potential outstanding performance catalysts for redox reaction.

scholarly journals Kinetics and Thermodynamics of CO Oxidation by (TiO2)6

2021 ◽  
Author(s):  
Navjot Kaur ◽  
Neetu Goel ◽  
Michael Springborg ◽  
Mohammad Molayem
Keyword(s):  
Co Oxidation ◽  
Active Sites ◽  
Density Functional ◽  
Harmonic Approximation ◽  
Oxidation Mechanism ◽  
Structural Isomers ◽  
Reactivity Descriptors ◽  
Co Oxidation Reaction ◽  
Adsorption Of Co ◽  
Global And Local

Molecular level insights into the mechanism and thermodynamics of CO oxidation by a (TiO) cluster have been obtained through density functional calculations. Thereby, we have considered as an example, two different structural isomers of (TiO) with the purpose of understanding the interplay between local structure and activity for the CO oxidation reaction. Active sites in the two isomeric forms were identified on the basis of global and local reactivity descriptors. For the oxidation of CO to CO2 we considered both sequential and simultaneous adsorption of CO and O2 on (TiO2)6 cluster through the ER and LH mechanisms, respectively. Three different pathways were obtained for CO oxidation by (TiO2)6 cluster, and the mechanistic route of each pathway were identified by locating the transition-state and intermediate structures. The effects of temperature on the rate of the reaction was investigated within the harmonic approximation. The structure-dependent activity of the cluster was rationalized through reactivity descriptors and analysis of the frontier orbitals. Finally, we also considered the effects of a support, i.e., graphene, on the oxidation mechanism.

CO adsorption on graphite-like ZnO bilayers supported on Cu(111), Ag(111) and Au(111) surfaces

2017 ◽  
Author(s):  
Sergio Tosoni ◽  
Cequn Li ◽  
Philomena Schlexer ◽  
Gianfranco Pacchioni
Keyword(s):  
Density Functional ◽  
Chemical Interaction ◽  
Co Adsorption ◽  
Density Functional Theory Calculations ◽  
Dispersion Interactions ◽  
Oxide Interface ◽  
Functional Theory ◽  
Bilayer Films ◽  
Coinage Metals ◽  
Co Probe

<div> <div> <div> <p>Graphitic-like ZnO bilayer films deposited on coinage metals, Cu(111), Ag(111), and Au(111) have been studied by density functional theory calculations including dispersion corrections. The scope is to compare on an equal footing the properties of the three systems and in particular the nature of the metal/oxide interface. To this end we have considered the adsorption of a CO probe molecule and the vibrational shifts induced by adsorption on ZnO/Cu(111), ZnO/Ag(111), and ZnO/Au(111) compared to adsorption on the unsupported ZnO bilayer and on the wurtzite ZnO surface. We find that while the interaction of ZnO with Ag and Au supports is dominated by dispersion interactions with little or no charge transfer at the interface, in the case of Cu a moderate electron transfer occurs towards the ZnO bilayer. As a consequence, while the stretching frequency of CO on ZnO/Au is blue-shifted, that on ZnO/Cu is red- shifted compared to free CO. CO on ZnO/Ag is intermediate. In all three cases, however, the ZnO bilayer is almost flat, with a modest rumpling found in the case of Cu as a consequence of the stronger chemical interaction. The results fully explain the CO vibrational shifts of CO on ZnO/Cu(111) [Schott, V. et al. Angew. Chem. Int. Ed. 2013, 52, 1-6] without implying major distortions in the supported film. </p> </div> </div> </div>

The Effect of Surface Defects on Chloride-Induced Depassivation of Iron—A Density Functional Theory Study

CORROSION ◽  
10.5006/3501 ◽  
2020 ◽  
Vol 76 (7) ◽  
pp. 690-697 ◽  
Author(s):  
Qin Pang ◽  
Hossein DorMohammadi ◽  
O. Burkan Isgor ◽  
Líney Árnadóttir
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Surface Defects ◽  
Flat Surface ◽  
Density Functional Theory Calculations ◽  
Step Edge ◽  
Defect Model ◽  
Functional Theory ◽  
Passive Oxide Film ◽  
Effect Of Surface

Chloride-induced depassivation is a large contributor to the degradation of metals, but defects are likely to play a key role in that process. Here density functional theory calculations are used to investigate the mechanism of the initial stages of chloride-induced depassivation of iron by studying the Cl interactions with stepped α-Fe2O3 (0001) surfaces and how that can lead to degradation of the passive oxide film. The low coordinated Fe sites near the step edge and O vacancies facilitate high local coverages of adsorbed Cl, which enhance surface Fe vacancy formation significantly. The step edge also lowers the Cl insertion energy, relative to the flat surface, but insertion by exchange with O is still endothermic. This study illustrates the importance of surface defects, step edges, and O vacancies in the depassivation mechanism, but the findings generally support the point defect model as a description of the depassivation mechanism.

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