Bimetallic Pd-Bi/C Catalysts Prepared by Grafting of Complexes with O-Donor Ligands
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ORIGINAL PAPER
Bimetallic Pd‑Bi/C Catalysts Prepared by Grafting of Complexes with O‑Donor Ligands Chantal Diverchy1 · Vincent Dubois2 · Michel Devillers1 · Sophie Hermans1 Accepted: 11 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Bimetallic carbon-supported PdBi catalysts were prepared by grafting. To do so a soluble complex of bismuth with exchangeable O-donor ligands was selected, and the carbon support was functionalized to increase the number of surface functions. The grafting procedure was carried out by contacting the various supports with solutions of Pd and/or Bi complexes, to allow ligand exchange reactions to take place between the complexes and the surface O-groups. The grafted fragments were then activated into carbon-supported nanoparticles, which were characterized to unravel the impact of grafting experimental variables on the physico-chemical characteristics of the materials obtained. The PdBi/C catalysts were finally tested in the archetypal glucose selective oxidation reaction, to assess the impact of those characteristics on the catalytic performance. It was found that simultaneous grafting gave larger nanoparticles than consecutive grafting, while higher number of stable surface functions allowed to obtain small and nicely distributed bimetallic nanoparticles. However, the surface functions were found to be deleterious for the catalytic activity, and the placement of the Bi promoter with respect to Pd active phase was identified as another key parameter for the activity, with grafting allowing to compare neatly samples where Bi is underneath, above or beside Pd. Keywords Grafting · Bismuth · Carbon · Oxidation · Liquid phase
1 Introduction For many heterogeneously catalyzed processes carried out in water or protic media, carbonaceous materials are unavoidable because other bulk or support materials are not stable under hydrothermal conditions [1, 2]. This is the case for example for carbohydrates that are efficiently catalytically transformed using carbon-supported catalysts in aqueous solution [3]. These sugar transformations might involve acidic sites for hydrolysis, dehydration or isomerization steps or metal nanoparticles for oxidation or hydrogenation. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11244-020-01376-y) contains supplementary material, which is available to authorized users. * Sophie Hermans [email protected] 1
Institute of Condensed Matter and Nanosciences (IMCN), UCLouvain, Place Louis Pasteur, 1, bte L4.01.03, 1348 Louvain‑la‑Neuve, Belgium
Department of Physical Chemistry and Catalysis, LABIRIS, 1 Avenue Emile Gryson, 1070 Brussels, Belgium
2
Each of these transformations has been studied since many years but bear current interest within the context of green and sustainable chemistry. Indeed, carbohydrates might be sourced out in lignocellulosic biomass and enter the so-called ‘biorefinery’ pathways [4, 5] to give high addedvalue platform compounds
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