Gold-palladium bimetallic catalysts for selective hydrogenation
Gold-palladium bimetallic catalysts for selective hydrogenation
Catherine Louis
Laboratoire de Réactivité de Surface, CNRS-Université Pierre et Marie Curie-UPMC, Paris
It has been demonstrated that catalytic performance can be improved by combining two metals [1]. The incorporation of the second metal leads to changes in the atomic and electronic structure of the nanoparticles and provides numerous advantages compared to monometallic catalysts [2]. In particular, five phenomena can be described [3]:
- Geometric effects, the active sites are altered due to geometric modifications.
- Electronic effects, the active sites are modified by electron transfer between metals.
- Stabilizing effects, by inhibiting sintering or suppressing the formation of carbonaceous deposits on the catalysts.
- Synergistic effects, both metals participate in the chemical bonding.
- Bi-functional effects, each metal provides a different function in the reaction mechanism.
After a brief presentation on the issue of bimetallic catalysts, the presentation will focus on the Au-Pd system for the selective hydrogenation of butadiene into butenes. This reaction is performed in the presence of an excess of alkene to mimic a process of purification of alkenes, necessary before alkene polymerization. Monometallic gold catalysts show a high selectivity in this reaction but a rather low activity [4]. The addition of a controlled amount of palladium to the gold nanoparticles induces enhanced catalytic activity compared to monometallic gold catalysts without loss of selectivity [5,6].
Different methods of catalyst preparation will be described. The presentation will also focus on the issue of the characterization of the bimetallic character of the Au-Pd catalysts. The issue of bimetallic particle restructuring will also be discussed [6,7,8].
References
[1] Tao, F., Synthesis, catalysis, surface chemistry and structure of bimetallic nanocatalysts. Chemical Society Reviews 2012, 41, 7977-7979.
[2] Piccolo, L., Surface Studies of Catalysis by Metals: Nanosize and Alloying Effects. In Nanoalloys, Alloyeau, D., Ed. Springer-Verlag London, 2012.
[3] Alonso, D. M.; Wettstein, S. G.; Dumesic, J. A., Bimetallic catalysts for upgrading of biomass to fuels and chemicals. Chemical Society Reviews 2012, 41, 8075-8098.
[4] A. Hugon, L. Delannoy, C. Louis, Gold Bull. 41 (2008) 127-138
[5] A. Hugon, L. Delannoy, J.-M. Krafft, C. Louis, J. Phys. Chem. C, 114 (2010) 10823
[6] N. El Kolli, L. Delannoy, C. Louis , J. Catal. 297 (2013) 79–92
[7] S. Giorgio, J.G. Mattei, C.R. Henry, N. El Kolli, L. Delannoy, C. Louis, ChemCatChem, 5 (2013) 2707-2716
[8] B. Zhu, G. Thrimurthulu, L. Delannoy, C. Louis, C. Mottet, J. Creuze, B. Legrand, H. Guesmi-Emery, Journal of Catalysis, 308 (2013) 272-281