Acetaldehyde partial oxidation on the Au(111) model catalyst surface: C–C bond activation and formation of methyl acetate as an oxidative coupling product

Karatok, Mustafa; Vovk, Evgeny I.; Shah, Asad A.; Türksoy, Abdurrahman; Özensoy, Emrah

doi:10.1016/j.susc.2015.04.005

Cited by 8 publications

(6 citation statements)

References 38 publications

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“…Atomic oxygen was accumulated on the Ag(111) model catalyst surface by ozone exposure using a methodology whose details can be found in one of our former papers . Ozone was dosed to the UHV system via Teflon tubings and a high-precision leak valve.…”

Section: Methodsmentioning

confidence: 99%

“…55 Ozone was dosed to the UHV system via Teflon tubings and a highprecision leak valve. NH 3 gas (Linde AG, purity ≥99.995%) was used without further purification and introduced onto the Ag(111) surface via a separate leak valve.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Atomic oxygen was accumulated on the Ag(111) model catalyst surface by ozone exposure using a methodology whose details can be found in one of our former papers. 55 Ozone was dosed to the UHV system via Teflon tubings and a highprecision leak valve. NH 3 gas (Linde AG, purity ≥99.995%) was used without further purification and introduced onto the Ag(111) surface via a separate leak valve.…”

Section: ■ Introductionmentioning

confidence: 99%

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Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

Karatok¹,

Vovk

Koç³

et al. 2017

J. Phys. Chem. C

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Ammonia-selective catalytic oxidation was studied on the planar Ag(111) single-crystal model catalyst surface under ultra-highvacuum (UHV) conditions. A variety of oxygen species were prepared via ozone decomposition on pristine Ag(111). Surface coverages of oxygen species were quantified by temperature-programmed desorption (TPD) and X-ray photoemission spectroscopy techniques. Exposure of ozone on Ag(111) at 140 K led to a surface atomic oxygen (O a ) overlayer. Lowenergy electron diffraction experiments revealed that annealing of this atomic oxygen-covered Ag(111) surface at 473 K in UHV resulted in the formation of ordered oxide surfaces (O ox ) with p(5×1) or c(4×8) surface structures. Ammonia interactions with O/Ag(111) surfaces monitored by temperature-programmed reaction spectroscopy indicated that disordered surface atomic oxygen selectively catalyzed N−H bond cleavage, yielding mostly N 2 along with minor amounts of NO and N 2 O. Higher coverage O/Ag(111) surfaces, whose structure was tentatively assigned to a bulklike amorphous silver oxide (O bulk ), showed high selectivity toward N 2 O formation (rather than N 2 ) due to its augmented oxygen density. In contrast, ordered surface oxide overlayers on Ag(111) (where the order was achieved by annealing the oxygen adlayer to 473 K) showed only very limited reactivity toward ammonia. The nature of the adsorbed NH 3 species on a clean Ag(111) surface and its desorption characteristics were also investigated via infrared reflection absorption spectroscopy and TPD techniques. Current findings demonstrate that the Ag(111) surface can selectively oxidize NH 3 to N 2 under well-defined experimental conditions without generating significant quantities of environmentally toxic species such as NO 2 , NO, or N 2 O.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

Karatok¹,

Vovk

Koç³

et al. 2017

J. Phys. Chem. C

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“…The role of gold in catalyzing C−C bond formation has been demonstrated in recent papers some of which deal with gold entities in solution . An Au–MCM‐22 system has shown the ability to couple carbon dioxide and ethane to produce propanoic acid .…”

Section: Resultsmentioning

confidence: 99%

The Conversion of Methanol into Higher Hydrocarbons Catalyzed by Gold

Gabriel

Scurrell

2016

ChemCatChem

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Gold/zinc oxide catalysts prepared by coprecipitation and containing gold particles of approximately 6 nm in diameter are active in the conversion of methanol to higher hydrocarbons under mild conditions. Conversions exceed 97 % under the selected experimental conditions at reaction temperatures of 350 °C, with a turnover number of 0.02 s−1. Both alkanes and alkenes up to C6 are formed, with a selectivity of approximately 44 %C hydrocarbons and 56 %C dimethyl ether. The addition of zeolite‐Y in composite catalysts modifies the product spectrum slightly. Ethene and propene dominate the alkenes formed above 450 °C if a 1:1 HY:Au/ZnO composite is used; the dominant alkane under these conditions is methane. At 475 °C only three hydrocarbons are present with selectivities of 13 (methane), 39 (ethene), and 48 % (propene). The carbon−carbon bond formation was not seen in earlier work when syngas (CO plus H2) was converted with the same Au/ZnO catalyst at high pressure to form mixtures of alcohols and hydrocarbons. This suggests that the formation of higher hydrocarbons from methanol is inhibited in the presence of CO and/or H2, probably due to competitive CO adsorption on the gold surface.

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“…Ozone was produced by a commercial ozone generator (Genozon, GN-G1001S, Turkey) and directly dosed on the sample through a leak valve. Additional details regarding the ozone delivery system can be found elsewhere . Oxygen coverages in this study were calculated based on oxygen temperature-programmed desorption (TPD) experiments on the clean Ag(111) surface, which was discussed in detail in one of our former reports .…”

Section: Methodsmentioning

confidence: 99%

Formaldehyde Selectivity in Methanol Partial Oxidation on Silver: Effect of Reactive Oxygen Species, Surface Reconstruction, and Stability of Intermediates

et al. 2021

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Selective oxidation reactions on heterogeneous silver catalysts are essential for the mass production of numerous industrial commodity chemicals. However, the nature of active oxygen species in such reactions is still debated. To shed light on the role of different oxygen species, we studied the methanol oxidation reaction on Ag(111) single-crystal model catalyst surfaces containing two dissimilar types of oxygen (electrophilic, O e and nucleophilic, O n ). X-ray photoelectron spectroscopy and low energy electron diffraction experiments suggested that the atomic structure of the Ag(111) surface remained mostly unchanged after accumulating low O e coverage at 140 K. Temperature-programmed reaction spectroscopic investigation of low coverages of O e on Ag(111) revealed that O e was active for methanol oxidation on Ag(111) with a high selectivity toward formaldehyde (CH 2 O) production. High surface oxygen coverages, on the other hand, triggered a reconstruction of the Ag(111) surface, yielding Ag oxide domains, which catalyzes methanol total oxidation to CO 2 and decreases the formaldehyde selectivity. This important finding indicates a trade-off between CH 2 O selectivity and methanol conversion, where 93% CH 2 O selectivity can be achieved for an oxygen surface coverage of θ O = 0.08 ML (ML = monolayer) with moderate methanol conversion, while methanol conversion could be boosted by a factor of ∼4 for θ O = 0.26 ML with a suppression of CH 2 O selectivity to 50%. Infrared reflection absorption spectroscopy results and density functional theory calculations indicated that Ag oxide contains dissimilar adsorption sites for methoxy intermediates, which are also energetically less stable than that of the unreconstructed Ag(111). The current findings provide important molecular-level insights regarding the surface structure of the oxidized Ag(111) model catalyst directly governing the competition between different reaction pathways in methanol oxidation reaction, ultimately dictating the reactant conversion and product selectivity.

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Acetaldehyde partial oxidation on the Au(111) model catalyst surface: C–C bond activation and formation of methyl acetate as an oxidative coupling product

Cited by 8 publications

References 38 publications

Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

The Conversion of Methanol into Higher Hydrocarbons Catalyzed by Gold

Formaldehyde Selectivity in Methanol Partial Oxidation on Silver: Effect of Reactive Oxygen Species, Surface Reconstruction, and Stability of Intermediates

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