Electronic properties of supported Pd aggregates in relation with their reactivity for 1,3-butadiene hydrogenation

The electronic and catalytic properties of supported Pd particles have been studied by measurements of XPS core level shifts and activity for 1,3-butadiene hydrogenation reaction respectively. For samples prepared by atom beam deposition on carbonaceous supports the TOF at steady state decreases rapidly with decreasing particle size in the range of particle diameter 2.8 nm-1.2 nm. For these small particles, the Pd 3d core level shows an upwards shift and a larger half width compared to the values for massive Pd samples. For the Pd/SiO2 particles of similar size, both the 3d core level energy and the TOF are comparable to these of the massive Pd systems.