Protection of industrially-relevant Pd/C catalysts for cyclohexene hydrogenation: effect of a siliceous coating on the thermal treatment of covered catalysts
Carbon-supported palladium catalysts were covered by a siliceous layer to increase their sintering resistance. A commercial Pd/C catalyst was compared to catalysts prepared either by dry impregnation or wet impregnation on activated carbon or carbon black. In the case of dry impregnation, the Pd active phase was shown to be located within the micropores of the carbon support. A smooth and thick siliceous layer was evidenced by electron microscopy. XPS showed that Pd was indeed covered by a layer containing Si atoms. In all cases, the catalytic activity was diminished by the presence of the protecting layer, but thermal treatment allowed increasing the activity by creating some porosity within the layer, therefore allowing access to the underlying active phase, without deleterious sintering. Carbon black proved its superiority thanks to its non-microporous nature, which allowed the Pd particles to be located at the interface with the siliceous coating hence making them more accessible.
KeywordsPalladium Carbon Silica Protection Sintering Deactivation
The authors wish to thank the Fonds de la Recherche Scientifique (FRS-FNRS, Belgium) with the assistance of the Fédération Wallonie-Bruxelles and the Belgian National Lottery, as well as the Université catholique de Louvain for funding. We are also grateful to the JSPS (KAKENHI Grant Number 22760599, Japan) for funding. We thank as well Johnson Matthey for the JM440 sample and Grégory Ploegaerts for ICP analyses.
- 10.Maxted EB (1951) Adv Catal 3:129–178Google Scholar
- 11.Petró J (1976) In: Szabó ZG, Kalló D (eds) Contact catalysis, vol 2. Elsevier, Amsterdam, pp 65–75Google Scholar
- 12.Hegedus LL, McCabe RW (1984) Catalyst poisoning. Marcel Dekker, New YorkGoogle Scholar
- 15.Moulijn JA, van Diepen AE, Kapteijn FF (2008) In: Ertl G, Knözinger H, Schüth F, Weitkamp J (eds) Handbook of heterogeneous catalysis. Wiley, Weinheim, pp 1829–1845Google Scholar
- 25.Liu H, Zhang L, Wang N, Sheng SuD (2014) Angew Chem Int Ed 53:12634–12638Google Scholar
- 34.Nakagawa K, Okayama T, Tanimoto Y, Sotowa K, Sugiyama S, Moriga T, Takenaka S, Mishida M (2012) Appl Catal A 13:419–420Google Scholar
- 37.Lemaitre JL, Menon PG, Delannay F (1984) The measurement of catalyst dispersion. In: Delannay F (ed) Characterization of heterogenous catalysts. Marcel Dekker, New YorkGoogle Scholar