Carbon nanofiber supported palladium catalyst for liquid-phase reactions -An active and selective catalyst for hydrogenation of cinnamaldehyde into hydrocinnamaldehyde

Carbon nanofibers (CNFs) prepared by decomposition of ethane over a Ni/alum ina catalyst, are used as support for palladium clusters. The carbon suppor t displays a mean diameter of 40-50 nm, lengths up to several tens of micro meters, as highlighted by transmission electron microscopy (TEM) observatio ns and a specific surface area of about 50 m(2)/g. The spheroidal palladium particles have a relatively homogeneous and sharp size distribution, cente red at around 4 nm. This novel Pd/carbon nanofiber catalyst displays unusua l catalytic properties and is successfully used in the selective hydrogenat ion of the C=C bond in cinnamaldehyde at a reaction temperature of around 8 0 degrees, under continuous hydrogen flowing at atmospheric pressure. The h igh performances of this novel catalyst in terms of efficiency and selectiv ity are, respectively, related to the inhibition of the mass-transfer proce sses over this non-porous material and to peculiar palladium-carbon interac tions. It is concluded that the absence of microporosity in the carbon nano fibers favours both the high activity and selectivity which is confirmed by comparison with the commercially available high surface area charcoal supp orted palladium catalyst. (C) 2001 Elsevier Science B.V. All rights reserve d.