Strain Dependent Light-off Temperature in Catalysis Revealed by Planar Laser-Induced Fluorescence

Blomberg, Sara; Zetterberg, Johan; Zhou, Jianfeng; Merte, Lindsay R.; Gustafson, Johan; Shipilin, Mikhail; Trinchero, Adriana; Miccio, Luis A.; Magaña, Ana; Ilyn, M.; Schiller, Frederik; Ortega, J. E.; Bertram, Florian; Grönbeck, Henrik; Lundgren, Edvin

doi:10.1021/acscatal.6b02440

Cited by 39 publications

(55 citation statements)

References 24 publications

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“…To overcome these problems, planar laser-induced fluorescence (PLIF) can be used to detect gases in the vicinity of a working catalyst in situ non-intrusively with high spatial and temporal resolution. A number of recent applications of PLIF have demonstrated it as a powerful gas detection tool, complementary to MS in catalysis studies [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Visualization of Gas Distribution in a Model AP-XPS Reactor by PLIF: CO Oxidation over a Pd(100) Catalyst

et al. 2017

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Abstract:In situ knowledge of the gas phase around a catalyst is essential to make an accurate correlation between the catalytic activity and surface structure in operando studies. Although ambient pressure X-ray photoelectron spectroscopy (AP-XPS) can provide information on the gas phase as well as the surface structure of a working catalyst, the gas phase detected has not been spatially resolved to date, thus possibly making it ambiguous to interpret the AP-XPS spectra. In this work, planar laser-induced fluorescence (PLIF) is used to visualize the CO 2 distribution in a model AP-XPS reactor, during CO oxidation over a Pd(100) catalyst. The results show that the gas composition in the vicinity of the sample measured by PLIF is significantly different from that measured by a conventional mass spectrometer connected to a nozzle positioned just above the sample. In addition, the gas distribution above the catalytic sample has a strong dependence on the gas flow and total chamber pressure. The technique presented has the potential to increase our knowledge of the gas phase in AP-XPS, as well as to optimize the design and operating conditions of in situ AP-XPS reactors for catalysis studies.

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Section: Introductionmentioning

confidence: 99%

Visualization of Gas Distribution in a Model AP-XPS Reactor by PLIF: CO Oxidation over a Pd(100) Catalyst

et al. 2017

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“…Recently, Lundgren and coworkers directly and elegantly compared the effect of the two different steps found on vicinal (111) surfaces (of fcc crystals) on the CO oxidation rate (w = 1 and p = 12 hPa). 156 To this end, a curved single crystal was studied with PLIF, yielding the local gas-phase composition, see Fig. 25.…”

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confidence: 99%

Surface science under reaction conditions: CO oxidation on Pt and Pd model catalysts

2017

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Platinum and palladium are frequently used as catalytic materials, for example for the oxidation of CO. This is one of the most widely studied reactions in the field of surface science. Although seemingly uncomplicated, it remains an active and interesting topic, which is partially explained by the push to conduct experiments on model systems under relevant reaction conditions. Recent developments in the surface-science methodology have allowed obtaining chemical and structural information on the active phase of model catalysts. Tools of the trade include near-ambient-pressure X-ray photoelectron spectroscopy, high-pressure scanning tunneling microscopy, high-pressure surface X-ray diffraction, and high-pressure vibrational spectroscopy. Interpretation is often aided by density functional theory in combination with thermodynamic and kinetic modeling. In this review, results for the catalytic oxidation of CO obtained by these techniques are compared. On several of the Pt and Pd surfaces, new structures develop in excess O 2 . For Pt, this requires a much larger excess of O 2 than for Pd. Most of these structures also develop in pure O 2 and are identified as (surface) oxides. A large body of evidence supports the conjecture that these oxides are more reactive than the corresponding O-covered metallic surfaces under similar conditions, although still debated in the literature. An outlook on this developing field, including directions that move away from CO oxidation towards more complex chemistry, concludes this review.

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“…This range of temperature is usually applied to partially light-off of carbon monoxide, as well as to fully light-off of hydrogen. Note that the light-off temperature refers to the temperature at which significant oxidation reactions occur [74]. These situations are usually encountered in the normal operating mode in both catalytic combustion gas turbine and microturbine systems, since the catalyst would attain the discharge temperature of the compressor as low as 600 K. It is important to note that a transition temperature of 550 K has been found by Zheng et al [10,16], below which the presence of hydrogen has an inhibiting effect on the catalytic oxidation of carbon monoxide over platinum under the conditions set out therein.…”

Section: Critical Temperaturementioning

confidence: 99%

Section: Critical Temperaturementioning

confidence: 99%

Catalytic Oxidation of Synthesis Gas on Platinum at Low Temperatures for Power Generation Applications

et al. 2018

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This paper addresses the issues related to the low-temperature catalytic oxidation of synthesis gas at high pressures under lean-burn conditions. The purpose of this study is to explore the mechanism responsible for the interplay between carbon monoxide and hydrogen during their combined oxidation process. Particular attention is given to the temperature range from 500 to 770 K, which is relevant to the catalyst inlet temperature encountered in catalytic combustion gas turbine systems. Computational fluid dynamics simulations were performed by using a numerical model with detailed chemistry and transport. Reaction path analysis was conducted, and the rate-determining step in the reaction mechanism was finally identified. It was shown that there is a strong interplay between carbon monoxide and hydrogen during the combined oxidation process. The addition of hydrogen causes a great change in the adsorbed species on the surface of the catalyst. At temperatures as low as 600 K, the presence of hydrogen makes the active surface sites more available for adsorption, thus promoting the catalytic oxidation of carbon monoxide. The coupling steps between the two components make a small contribution to the promoting effect. At temperatures below 520 K, the presence of hydrogen inhibits the catalytic oxidation of carbon monoxide due to the competitive effect of hydrogen on oxygen adsorption.

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Strain Dependent Light-off Temperature in Catalysis Revealed by Planar Laser-Induced Fluorescence

Cited by 39 publications

References 24 publications

Visualization of Gas Distribution in a Model AP-XPS Reactor by PLIF: CO Oxidation over a Pd(100) Catalyst

Visualization of Gas Distribution in a Model AP-XPS Reactor by PLIF: CO Oxidation over a Pd(100) Catalyst

Surface science under reaction conditions: CO oxidation on Pt and Pd model catalysts

Catalytic Oxidation of Synthesis Gas on Platinum at Low Temperatures for Power Generation Applications

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