scholarly journals Stroboscopic operando spectroscopy of the dynamics in heterogeneous catalysis by event-averaging

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jan Knudsen ◽  
Tamires Gallo ◽  
Virgínia Boix ◽  
Marie Døvre Strømsheim ◽  
Giulio D’Acunto ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Metallic Surface ◽  
Reaction Conditions ◽  
Catalyst Structure ◽  
Time Resolved ◽  
Poisoning Effect ◽  
Highly Active ◽  
Co Oxidation Reaction ◽  
Gas Environment

AbstractHeterogeneous catalyst surfaces are dynamic entities that respond rapidly to changes in their local gas environment, and the dynamics of the response is a decisive factor for the catalysts’ action and activity. Few probes are able to map catalyst structure and local gas environment simultaneously under reaction conditions at the timescales of the dynamic changes. Here we use the CO oxidation reaction and a Pd(100) model catalyst to demonstrate how such studies can be performed by time-resolved ambient pressure photoelectron spectroscopy. Central elements of the method are cyclic gas pulsing and software-based event-averaging by image recognition of spectral features. A key finding is that at 3.2 mbar total pressure a metallic, predominantly CO-covered metallic surface turns highly active for a few seconds once the O2:CO ratio becomes high enough to lift the CO poisoning effect before mass transport limitations triggers formation of a √5 oxide.

scholarly journals Stroboscopic operando spectroscopy of the dynamics in heterogeneous catalysis by event-averaging

2021 ◽  
Author(s):  
Jan Knudsen ◽  
Tamires Gallo ◽  
Virgínia Boix ◽  
Marie Strømsheim ◽  
Giulio D'Acunto ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Oxidation Reaction ◽  
Ambient Pressure ◽  
Reaction Conditions ◽  
Catalyst Structure ◽  
Time Resolved ◽  
Co Oxidation Reaction ◽  
Surface Phases ◽  
Gas Environment

Abstract Heterogeneous catalyst surfaces are highly dynamic entities that respond rapidly to changes in their local gas environment, and the dynamics of the response is a decisive factor for the catalysts’ action and activity. Few probes are able to map catalyst structure and local gas environment simultaneously under reaction conditions at the time scales of the dynamic changes. Here we use the CO oxidation reaction over a Pd(100) surface exposed to pressures of 3 and 100 mbar of a CO + O2 gas mixture to demonstrate how such studies can be performed by time-resolved ambient pressure photoelectron spectroscopy. Central elements of the method are cyclic gas pulsing and software-based event-averaging by image recognition of spectral features. For the CO oxidation reaction over Pd(100) our main finding is that that all surface phases – the CO-covered Pd surface, a surface oxide and a thick PdOx phase – catalyse the CO oxidation reaction, in dependence on the supply of gas phase reactants.

Synergistic effect of co-reactant promotes one-step oxidation of cyclohexane into adipic acid catalyzed by manganese porphyrins

2015 ◽  
Vol 93 (7) ◽  
pp. 696-701 ◽  
Author(s):  
Hui Li ◽  
Yuanbin She ◽  
Haiyan Fu ◽  
Meijuan Cao ◽  
Jing Wang ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Co Oxidation ◽  
Adipic Acid ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Catalyst Structure ◽  
Manganese Porphyrins ◽  
Co Oxidation Reaction ◽  
One Step ◽  
Acid Catalyzed

The synergistic effect of cyclohexane and cyclohexanone promoted synthesis of adipic acid catalyzed by [MnIIIT(p-Cl)PP]Cl with cyclohexane and cyclohexanone as co-reactants. The results showed that the conversions of cyclohexane and cyclohexanone were significantly enhanced because of the cyclohexanone synergistic effect, and the higher selectivity to adipic acid was obtained with dioxygen as an oxidant. The studies indicated that the co-oxidation of cyclohexane and cyclohexanone was influenced by the initial molar ratio of cyclohexanone and cyclohexane, catalyst structure, catalyst concentrations, and reaction conditions. The preliminary mechanism of the co-oxidation reaction of cyclohexane and cyclohexanone using [MnIIIT(p-Cl)PP]Cl as the catalyst was proposed.

scholarly journals Breaking Simple Scaling Relations Through Metal-Oxide Interactions: Understanding Room Temperature Activation of Methane on M-CeO2 (M= Pt, Ni or Co) Interfaces

2020 ◽  
Author(s):  
Pablo Lustemberg ◽  
Feng Zhang ◽  
Ramón A. Gutiérrez ◽  
Pedro J. Ramírez ◽  
Sanjaya D. Senanayake ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Ambient Pressure ◽  
Scaling Relations ◽  
Time Resolved ◽  
X Ray ◽  
Metal Support ◽  
Simple Scaling

The clean activation of methane at low temperatures remains an eminent challenge and a field of competitive research. In particular, on late transition metal surfaces such as Pt(111) or Ni(111), elevated temperatures are necessary to activate the hydrocarbon molecule, but a massive deposition of carbon makes the metal surface useless for catalytic activity. However, on very low-loaded M/CeO2 (M= Pt, Ni, or Co) surfaces, the dissociation of methane occurs at room temperature, which is unexpected considering simple linear scaling relationships. This intriguing phenomenon has been studied using a combination of experimental techniques (ambient-pressure X-ray photoelectron spectroscopy, time-resolved X-ray diffraction and X-ray absorption spectroscopy) and density functional theory-based calculations. The experimental and theoretical studies show that the size and morphology of the supported nanoparticles together with strong metal-support interactions are behind the deviations from the scaling relations. These findings point toward a possible strategy to circumvent scaling relations, producing active and stable catalysts which can be employed for methane activation and conversion. <br>

scholarly journals Synchronizing Gas Injections and Time-Resolved Data Acquisition for Perturbation-Enhanced APXPS Experiments

2020 ◽  
Author(s):  
Evgeniy Redekop ◽  
Niclas Johansson ◽  
Esko Kokkonen ◽  
Samuli Urpelainen ◽  
Felipe Lopes da Silva ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Surface Science ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Atomic Layer ◽  
Time Resolved ◽  
Layer Deposition ◽  
Wafer Substrate ◽  
Line Detector ◽  
Properties Of Materials

An experimental approach is described in which well-defined perturbations of the gas feed into an Ambient Pressure X-Ray Photoelectron Spectroscopy (APXPS) cell are digitally synchronized with time-resolved XPS data acquisition with a Delay Line Detector (DLD). These experiments unlock new possibilities for investigating the properties of materials and chemical reactions mediated by their surfaces, such as those in heterogeneous catalysis, surface science, and coating/deposition applications. Implementation of this approach, which is termed perturbation-enhanced APXPS, at the SPECIES beamline of MAX-IV Laboratory is discussed along with several experimental examples including (1) individual pulses of N2 gas over Au foil, a multi-pulse titration of oxygen vacancies in a pre-reduced TiO2 single crystal with O2 gas, and a sequence of alternating precursor pulses for Atomic Layer Deposition (ALD) of TiO2 on a silicon wafer substrate.<br>

scholarly journals Breaking Simple Scaling Relations Through Metal-Oxide Interactions: Understanding Room Temperature Activation of Methane on M-CeO2 (M= Pt, Ni or Co) Interfaces

2020 ◽  
Author(s):  
Pablo Lustemberg ◽  
Feng Zhang ◽  
Ramón A. Gutiérrez ◽  
Pedro J. Ramírez ◽  
Sanjaya D. Senanayake ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Ambient Pressure ◽  
Scaling Relations ◽  
Time Resolved ◽  
X Ray ◽  
Metal Support ◽  
Simple Scaling

The clean activation of methane at low temperatures remains an eminent challenge and a field of competitive research. In particular, on late transition metal surfaces such as Pt(111) or Ni(111), elevated temperatures are necessary to activate the hydrocarbon molecule, but a massive deposition of carbon makes the metal surface useless for catalytic activity. However, on very low-loaded M/CeO2 (M= Pt, Ni, or Co) surfaces, the dissociation of methane occurs at room temperature, which is unexpected considering simple linear scaling relationships. This intriguing phenomenon has been studied using a combination of experimental techniques (ambient-pressure X-ray photoelectron spectroscopy, time-resolved X-ray diffraction and X-ray absorption spectroscopy) and density functional theory-based calculations. The experimental and theoretical studies show that the size and morphology of the supported nanoparticles together with strong metal-support interactions are behind the deviations from the scaling relations. These findings point toward a possible strategy to circumvent scaling relations, producing active and stable catalysts which can be employed for methane activation and conversion. <br>

scholarly journals Synchronizing Gas Injections and Time-Resolved Data Acquisition for Perturbation-Enhanced APXPS Experiments

2021 ◽  
Author(s):  
Evgeniy Redekop ◽  
Niclas Johansson ◽  
Esko Kokkonen ◽  
Samuli Urpelainen ◽  
Felipe Lopes da Silva ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Surface Science ◽  
Photoelectron Spectroscopy ◽  
Experimental Approach ◽  
Ambient Pressure ◽  
Atomic Layer ◽  
Time Resolved ◽  
Layer Deposition ◽  
Wafer Substrate ◽  
Properties Of Materials

An experimental approach is described in which well-defined perturbations of the gas feed into an Ambient Pressure X-Ray Photoelectron Spectroscopy (APXPS) cell are fully synchronized with the time-resolved XPS data acquisition. These experiments unlock new possibilities for investigating the properties of materials and chemical reactions mediated by their surfaces, such as those in heterogeneous catalysis, surface science, and coating/deposition applications. Implementation of this approach, which is termed perturbation-enhanced APXPS, at the SPECIES beamline of MAX IV Laboratory is discussed along with several experimental examples including individual pulses of N2 gas over Au foil, a multi-pulse titration of oxygen vacancies in a pre-reduced TiO2 single crystal with O2 gas, and a sequence of alternating precursor pulses for Atomic Layer Deposition (ALD) of TiO2 on a silicon wafer substrate.

scholarly journals Synchronizing Gas Injections and Time-Resolved Data Acquisition for Perturbation-Enhanced APXPS Experiments

2020 ◽  
Author(s):  
Evgeniy Redekop ◽  
Niclas Johansson ◽  
Esko Kokkonen ◽  
Samuli Urpelainen ◽  
Felipe Lopes da Silva ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Surface Science ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Atomic Layer ◽  
Time Resolved ◽  
Layer Deposition ◽  
Wafer Substrate ◽  
Line Detector ◽  
Properties Of Materials

An experimental approach is described in which well-defined perturbations of the gas feed into an Ambient Pressure X-Ray Photoelectron Spectroscopy (APXPS) cell are digitally synchronized with time-resolved XPS data acquisition with a Delay Line Detector (DLD). These experiments unlock new possibilities for investigating the properties of materials and chemical reactions mediated by their surfaces, such as those in heterogeneous catalysis, surface science, and coating/deposition applications. Implementation of this approach, which is termed perturbation-enhanced APXPS, at the SPECIES beamline of MAX-IV Laboratory is discussed along with several experimental examples including (1) individual pulses of N2 gas over Au foil, a multi-pulse titration of oxygen vacancies in a pre-reduced TiO2 single crystal with O2 gas, and a sequence of alternating precursor pulses for Atomic Layer Deposition (ALD) of TiO2 on a silicon wafer substrate.<br>

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