Decomposition of methanol by Pd, Co, and bimetallic Co–Pd catalysts: A combined study of well-defined systems under ambient and UHV conditions

Borchert, Holger; Jürgens, Birte; Nowitzki, Tobias; Behrend, Peter; Borchert, Yu.; Zielasek, Volkmar; Giorgio, S.; Henry, Claude R.; Bäumer, Marcus

doi:10.1016/j.jcat.2008.02.017

Cited by 30 publications

(34 citation statements)

References 45 publications

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“…Additionally, the influence of adsorbed oxygen or oxidic phases, for example, those generated by CÀO bond scission, on the methanol dehydrogenation is investigated in the case of Co, which is particularly prone to changes in surface chemistry by surface and subsurface oxygen species. [37] Finally, by comparing the results obtained under UHV conditions to the findings obtained in continuous-flow reactors under ambient conditions, [38] we demonstrate that the UHV studies are of high relevance for understanding the reactions on real catalyst surfaces.…”

Section: Introductionmentioning

confidence: 75%

“…[38] At partial pressures of up to 100 mbar methanol, the IR spectra proved the formation of carbon monoxide at 300 K for all particle systems. Experiments in fixed-bed reactors, however, did not show significant conversion below the desorption temperatures of carbon monoxide from the various metals, which confirmed the desorption limitation of the reaction also under high-pressure conditions.…”

Section: Càh Scission: Carbon Monoxide and Hydrogen Formationmentioning

confidence: 88%

“…Thus, well-defined Pd, Co, and alloy nanoparticles prepared by wet-impregnation on MgO were studied in our laboratory in parallel. [38] In the following, the two pathways are discussed. In each case, the conclusions of the present work are checked with respect to their relevance for the catalytic properties under ambient pressures.…”

Section: Discussionmentioning

confidence: 99%

“…At first sight this result is unexpected, as the pretreatments applied in the catalytic study allow the conclusion that the particles were not metallic but oxidic (probably CoO). [38] The findings of the UHV study provide an explanation for this behavior: as methanol can reduce Co oxide particles, reduction can take place concomitant to the decomposition presumably leading to almost metallic behavior.…”

Section: Càh Scission: Carbon Monoxide and Hydrogen Formationmentioning

confidence: 90%

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UHV Studies of Methanol Decomposition on Mono‐ and Bimetallic CoPd Nanoparticles Supported on Thin Alumina Films

et al. 2008

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Bimetallic nanoparticles often turn out to be superior to the corresponding monometallic systems with respect to their catalytic properties. To study such effects for the methanol decomposition reaction, model catalysts were prepared by physical vapor deposition of Pd and Co under ultrahigh-vacuum (UHV) conditions. Monometallic Pd and Co particles as well as CoPd core-shell particles were generated on an epitaxial alumina film grown on NiAl(110). The interaction with methanol is examined by temperature-programmed desorption of methanol and carbon monoxide and by X-ray photoelectron spectroscopy. The decomposition of methanol proceeds in two reaction pathways independent of the particle composition: complete dehydrogenation towards carbon monoxide and hydrogen, and C--O bond scission yielding carbon deposits. Pd is the most active material studied here. The relative importance of the two channels varies for the different particle systems: on Pd dehydrogenation is preferred, whereas the C--O bond cleavage is more pronounced on Co. The bimetallic clusters show a moderate performance for both pathways. Carbon deposition poisons the model catalysts by blocking the adsorption sites for methoxide, which is the first intermediate product during methanol decomposition. In particular on Co, large amounts of carbon deposits can also be caused by dissociation of the final product of the dehydrogenation pathway, carbon monoxide. A comparison with the results of methanol decomposition on Co, Pd, and CoPd catalysts in continuous-flow reactors demonstrates that the findings of the present UHV study are relevant for catalytic performance under high-pressure conditions.

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Section: Introductionmentioning

confidence: 75%

Section: Càh Scission: Carbon Monoxide and Hydrogen Formationmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Càh Scission: Carbon Monoxide and Hydrogen Formationmentioning

confidence: 90%

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UHV Studies of Methanol Decomposition on Mono‐ and Bimetallic CoPd Nanoparticles Supported on Thin Alumina Films

et al. 2008

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“…[4][5][6] Especially, catalysts based on noble metals have been intensively studied. [7][8][9][10] However, their performance is not yet satisfactory. In addition, noble metals should be avoided from the view points of lacking in resource and high cost.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Properties of Cold-Rolled Ni<SUB>3</SUB>(Si,Ti) Intermetallic Foils for Methanol Decomposition

et al. 2010

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Methanol decomposition tests were carried out for the first time on cold-rolled Ni 3 (Si,Ti) foils in a temperature range of 513-793 K to investigate their potential catalytic properties for hydrogen production. The catalytic activity was observed at temperatures above 713 K. At 793 K, the catalytic activity changed with the reaction time in three stages: low-activity incubation, rapid spontaneous activation and highactivity state. Surface analysis revealed an intensive formation of fine Ni particles on the foil surfaces after the second stage where rapid spontaneous activation was observed. The formation of the fine Ni particles was considered to be induced by the selective oxidation of Si in Ni 3 (Si,Ti). The catalytic activity in the second and third stages was due to the fine Ni particles formed by the spontaneous activation.

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Electronic Structure Evolution of Pd@Co Nanocatalysts Under Oxidation and Reduction Conditions and Preferential CO Oxidation

Jain

Gopinath

2020

ChemCatChem

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Herein, we present the surface electronic structure and morphological evolution under reduction and oxidation conditions for Pd@Co (PC) core‐shell nanoparticles with different Pd : Co ratio (PC=2 : 1, 1 : 1 and 1 : 2). Extensive measurements have been made with NAPXPS (near ambient pressure x‐ray photoelectron spectroscopy) under oxidising and reducing conditions, and ex‐situ HRTEM. It has been demonstrated that PC catalysts are thermally stable towards morphological changes, at least up to 575 K. Nonetheless, it shows a significant surface electronic structure changes under reaction environments, which are highly relevant to heterogeneous catalysis. As expected, high (low) population of metallic (oxidised) Co was observed, while retaining core shell structure under reduction (H2 and vacuum annealing) environment. Interestingly, the Pd−Co metallic interface helps to overcome the pyrophoric nature of cobalt and stabilised a significant amount of metallic Co at Pd−Co interface even in the presence of 0.1 mbar O2 up to 575 K. The presence of Pd−Co and Pd−Co@Co3O4 interfaces in reaction environment makes the catalyst dual functional. The proof of concept has been explored in terms of oxidation of CO in the presence of H2 or O2.

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Decomposition of methanol by Pd, Co, and bimetallic Co–Pd catalysts: A combined study of well-defined systems under ambient and UHV conditions

Cited by 30 publications

References 45 publications

UHV Studies of Methanol Decomposition on Mono‐ and Bimetallic CoPd Nanoparticles Supported on Thin Alumina Films

UHV Studies of Methanol Decomposition on Mono‐ and Bimetallic CoPd Nanoparticles Supported on Thin Alumina Films

Catalytic Properties of Cold-Rolled Ni<SUB>3</SUB>(Si,Ti) Intermetallic Foils for Methanol Decomposition

Electronic Structure Evolution of Pd@Co Nanocatalysts Under Oxidation and Reduction Conditions and Preferential CO Oxidation

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