Structure and Composition of Au–Cu and Pd–Cu Bimetallic Catalysts Affecting Acetylene Reactivity

Murugadoss, Arumugam; Sorek, Elishama; Asscher, Micha

doi:10.1007/s11244-014-0264-x

Cited by 8 publications

(11 citation statements)

References 30 publications

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“…The buffer material was amorphous solid water (ASW), and the metal atoms were simultaneously deposited on top of 20 MLs of ASW at 110 K. Pd−Cu bimetallic nanoclusters were subsequently softly deposited on the SiO 2 /Ru(0001) substrate upon desorption of the buffer ASW film at 165 K, resulting in clusters’ typical size range of 5 ± 2 nm. We attempted to investigate the role of the underlying Ru(0001) metallic substrate on the chemistry (acetylene decomposition with subsequent hydrogenation to ethylene and its trimerization to benzene) developed on top of the bimetallic clusters and compared it to similar reactivity studies performed earlier on the SiO 2 /Si(100) substrate …”

Section: Results and Discussionmentioning

confidence: 99%

“…In this report, we describe the mechanism underlying the reactivity of acetylene for the formation of ethylene and benzene because of supported bimetallic Pd−Cu NPs on the thin silica on ruthenium substrate. This reactivity is then compared to studies under identical conditions (the same Pd−Cu bimetallic clusters) on top of the relatively thick (about 2.5 nm) amorphous native silica grown on the Si(100) substrate . Where the oxide layer is very thin, charge transfer may occur between the suboxide metal and the metallic NPs on top.…”

Section: Introductionmentioning

confidence: 99%

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Acetylene Reactivity on Pd−Cu Nanoparticles Supported on Thin Silica Films: The Role of the Underlying Substrate

et al. 2019

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Heterogeneous chemistry that develops on ultrathin films such as bilayer SiO 2 /Ru(0001) is interesting as a model catalysis system. We have studied the partial decomposition and hydrogenation of acetylene to ethylene and its trimerization to benzene on Pd−Cu bimetallic alloy nanoparticles (NPs) supported on those thin silica films. In comparing the bilayer SiO 2 /Ru(0001) to thicker silica layers without a metallic substrate, for example, the native SiO 2 /Si(100), the size distribution of the clusters is narrower on the bilayer SiO 2 /Ru(0001) substrate, demonstrating the effect of the underlying metal in preventing cluster diffusion during their growth. In addition, the effect of medium pressure on the NP shape has been investigated via transmission electron microscopy imaging of the NPs on relatively thick SiO 2 . The NPs become elongated when exposed to 0.2 mbar acetylene inside a moderate-pressure cell embedded within an ultrahigh vacuum (UHV) chamber. By changing the elemental composition of the NPs on both substrates, the important effect of the suboxide material on catalyst reaction selectivity has been demonstrated. However, the effect of the composition of the bare NPs is not enough to actually define the long-term activity of a catalyst. In order to address more realistic conditions, we performed consecutive reactivity cycles by adsorbing acetylene at 110 K with subsequent annealing up to 400 K in UHV on the same 1Pd:1Cu NPs/bilayer SiO 2 /Ru(0001) catalyst. This revealed a strong decrease in the selectivity toward ethylene, from an ethylene/benzene product yield ratio of 370 ± 150 in the first cycle down to 50 ± 15 during the third to fifth cycles. Carbon atom accumulation on the metallic particles in the first and subsequent runs is the main reason for this modification in selectivity. A consecutive reactivity study uniquely demonstrates how rapidly and significantly the catalyst's performance is modified during the initial stages of its heterogeneous catalytic reactivity.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Acetylene Reactivity on Pd−Cu Nanoparticles Supported on Thin Silica Films: The Role of the Underlying Substrate

et al. 2019

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“…This technique can also produce porous [4][5][6] or fractal 7,8 nanostructures with incredibly high surface to volume ratios. Due to their potential applications in catalysis, [9][10][11][12] efficient solar energy conversion, 13,14 antimicrobial coatings, [15][16][17] magnetic memory arrays, 18 etc., studies on these types of nanostructures are very promising from both a basic research and technological perspective. Copper is a material with high abundance in nature 19 and is a promising candidate for use in most of the above mentioned elds.…”

Section: Introductionmentioning

confidence: 99%

Oxidation behaviour of copper nanofractals produced by soft-landing of size-selected nanoclusters

Mondal

Bhattacharyya

2015

RSC Adv.

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“…12 In Pd−Cu alloy nanoparticles, palladium is the more active element, but synergetic advantages lead to a higher reactivity of the alloy than when each of the elements are compared separately. 13,14 Whereas on copper particles the acetylene adsorbs nondissociatively, 15,16 the role of the palladium sites is to supply hydrogen atoms to the deactivated copper surfaces and regenerate them into active metallic copper sites. 17 In very thin oxide layers (<1 nm thickness) such as the bilayer SiO 2 /Ru(0001), charge transfer occurs through these layers, enabling interactions between the suboxide supporting metal and the active metal particles on top of the oxide layer.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In Pd–Cu alloy nanoparticles, palladium is the more active element, but synergetic advantages lead to a higher reactivity of the alloy than when each of the elements are compared separately. , Whereas on copper particles the acetylene adsorbs nondissociatively, , the role of the palladium sites is to supply hydrogen atoms to the deactivated copper surfaces and regenerate them into active metallic copper sites …”

Section: Introductionmentioning

confidence: 99%

Medium-Pressure Reactivity of Acetylene on Pd–Cu Alloy Nanoparticles Supported on Thin Silica Films

2020

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The ability to correlate industrial high-pressure catalysis with high-vacuum research has been of great interest for decades. We employed a double-chamber vacuum system to study the self-hydrogenation of acetylene to ethylene and its trimerization to benzene at medium pressures to compare the reactivity in this pressure range to the known model catalytic acetylene reactivity in ultrahigh vacuum (UHV). We measured the reactivity of Pd–Cu bimetallic alloy nanoparticles (ANPs) with different elemental compositions deposited on top of native SiO2/Si(100) and on bilayer SiO2/Ru(0001) surfaces, where the latter was shown to contribute to ANP stability. Following exposure to 0.5 mbar of acetylene, ANPs on both surfaces catalyze the formation of ethylene and benzene, with ethylene as the more probable product. The ANPs on bilayer SiO2/Ru(0001) were highly selective toward ethylene formation, with an ethylene/benzene ratio of more than 2 orders of magnitude, whereas on the native SiO2/Si(100) there was a significantly lower selectivity (about 5) at the same temperature range and catalyst elemental composition. Interestingly, these selectivity values are similar to those found under UHV conditions. In addition, ANPs grown on native SiO2/Si(100), unlike SiO2/Ru(0001), revealed an optimal temperature for ethylene and benzene formation due to the limited stability of the particles.

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Structure and Composition of Au–Cu and Pd–Cu Bimetallic Catalysts Affecting Acetylene Reactivity

Cited by 8 publications

References 30 publications

Acetylene Reactivity on Pd−Cu Nanoparticles Supported on Thin Silica Films: The Role of the Underlying Substrate

Acetylene Reactivity on Pd−Cu Nanoparticles Supported on Thin Silica Films: The Role of the Underlying Substrate

Oxidation behaviour of copper nanofractals produced by soft-landing of size-selected nanoclusters

Medium-Pressure Reactivity of Acetylene on Pd–Cu Alloy Nanoparticles Supported on Thin Silica Films

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