The roles of carbide and hydride in oxide-supported palladium nanoparticles for alkyne hydrogenation

Tew, Min Wei; Janousch, M.; Huthwelker, Thomas; Bokhoven, Jeroen A. van

doi:10.1016/j.jcat.2011.06.025

Cited by 107 publications

(103 citation statements)

References 54 publications

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“…We propose the as-prepared catalyst comprised a metallic palladium core encapsulated by a multilayer palladium oxide shell, akin to Pd/SBA-15 [22] (Figure 8 and Table S1); fits to a two-phase mixture of oxide, metal or carbide were poor ( Figure S8 and Table S2). Palladium carbide is known to form via surface-mediated reactions with gaseous hydrocarbons at ambient temperature [53,54] or CO decomposition, resulting in a characteristic Pd-C scattering feature ~2.16 Å and concomitant palladium lattice expansion [55]. Good fits were obtained only though including additional shells, Pd-C at 2.16 Å and an expanded Pd-Pd shell at ~2.84 Å [54].…”

Section: Operando Xas Studies Of Cinnamyl Alcohol Seloxmentioning

confidence: 99%

Alumina-grafted SBA-15 as a high performance support for Pd-catalysed cinnamyl alcohol selective oxidation

et al. 2014

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eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Operando, liquid phase XAS highlights the interplay between dissolved oxygen and the oxidation state of palladium nanoparticles dispersed over Al-SBA-15 towards on-stream reduction: ambient pressures of flowing oxygen are sufficient to hinder palladium oxide reduction to metal, enabling a high selox activity to be maintained, whereas rapid PdO reduction and concomitant catalyst deactivation occurs under static oxygen.Selectivity to the desired cinnamaldehyde product mirrors these trends in activity, with flowing oxygen minimising C-O cleavage of the cinnamyl alcohol reactant to trans--methylstyrene, and of cinnamaldehyde decarbonylation to styrene. Highlights: An ultrathin alumina coating has been grafted onto a SBA-15 mesoporous silica architecture. Pd impregnated Al-SBA-15 materials are superior catalysts for the aerobic selox of allylic alcohols to aldehydes compared to pure silica or alumina supports.  Operando XAS confirms cinnamyl alcohol selox occurs over a PdO active species, which is prone to on-stream reduction and associated catalyst deactivation under static oxygen. [20,21] have highlighted PdO reduction to metallic palladium as a potential deactivation pathway, and hence the importance of generating highly dispersed nanoparticles which favour an oxide phase [20,[22][23][24]. KeywordsTemperature-programmed desorption and XPS of crotyl alcohol (but-2-en-1-ol) and crotonaldehyde (but-2-en-1-al) over Pd(111) and palladium-rich Au/Pd surface alloys suggest deactivation arises from crotonaldehyde decarbonylation and subsequent site-blocking by strongly adsorbed propylidyne and CO [20,21]. Computational modelling predicts Pd(111) can also drive propanoic acid decarbonylation [25]. Vapour phase studies of crotyl alcohol oxidation show that such in-situ palladium reduction is reversible under oxidising environments [17,19], enabling selox to be maintained, however the ability of dissolved oxygen to preserve palladium as PdO during liquid phase selox is unknown. Experimental Catalyst synthesisThe parent SBA-15 silica framework was synthesised following the method of Zhao et al [30]. Pluronic P123 (10 g) was dissolved in water (75.5 ...

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Section: Operando Xas Studies Of Cinnamyl Alcohol Seloxmentioning

confidence: 99%

Alumina-grafted SBA-15 as a high performance support for Pd-catalysed cinnamyl alcohol selective oxidation

et al. 2014

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“…29 It was found that the particle size of the oxide-supported Pd-NPs had an effect on the catalytic activity and selectivity for the hydrogenation of 1-pentyne. It was also found that the larger Pd-NPs were more selective due to the weaker bond strength of 1-pentene.…”

Section: Hydrogenation Of Alkynesmentioning

confidence: 99%

Nanocatalysts for Hydrogenation Reactions

Narayanan

2013

Nanocatalysis Synthesis and Applications

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“…In particular, palladium is one of the best-performing metal catalysts for selective hydrogenation of alkynes [10][11][12][13][14]. Numerous studies focus on the size-and shape-dependent properties of palladium NPs [15][16][17][18][19], indicating that controlling the size and shape distribution of NPs during synthesis is an important step in designing functional materials with the required parameters for practical applications.…”

Section: Introductionmentioning

confidence: 99%

Chemical Synthesis and Characterization of Pd/SiO2: The Effect of Chemical Reagent

Bugaev

Polyakov

Tereshchenko

et al. 2018

Metals

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The size and shape distribution of metal nanoparticles (NPs) are important parameters that need to be tuned in order to achieve desired properties of materials for practical applications. In the current work, we present the synthesis of palladium NPs supported on silica by three different methods, applying reduction by sodium borohydride, hydrazine vapors, and polyethylene glycol (PEG). The synthesized materials were characterized by X-ray diffraction, X-ray fluorescence, transmission electron microscopy, surface area and porosity measurements, and thermogravimetric analysis. Similar nanoparticle sizes with narrow size distribution centered at 8 nm were obtained after reduction by sodium borohydride and hydrazine vapors, whereas the smallest particle size of about 4.8 nm was obtained after reduction by PEG. The effect of modification of the initial palladium chloride compound by ammonium hydroxide was found to lead to the formation of larger particles with average size of 15 nm and broader size distribution. In addition, the process of the reduction of palladium by PEG at different reduction stages was monitored by UV-Vis spectroscopy. CO-stripping voltammetry showed that reduction in hydrazine and in PEG allowed the preparation of Pd NPs with high electrochemically-active surface area. Such NPs are promising materials for electrocatalysis.

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The roles of carbide and hydride in oxide-supported palladium nanoparticles for alkyne hydrogenation

Cited by 107 publications

References 54 publications

Alumina-grafted SBA-15 as a high performance support for Pd-catalysed cinnamyl alcohol selective oxidation

Alumina-grafted SBA-15 as a high performance support for Pd-catalysed cinnamyl alcohol selective oxidation

Nanocatalysts for Hydrogenation Reactions

Chemical Synthesis and Characterization of Pd/SiO2: The Effect of Chemical Reagent

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