Selective butadiene hydrogenation by Pd nanoparticles deposed onto nano-sized oxide supports by CVD of Pd-hexafluoroacetylacetonate.

The organometallics chemical vapor deposition (OM-CVD) technique, using Pd(hfac)2 as a precursor, was employed for the preparation of a series of heterogeneous catalysts based on Pd nanoparticles supported on nanometric oxides (CeO2, ZnO and TiO2). The properties of metal nanoparticles were tuned by proper pretreatment of the oxidic support. Complete decomposition of Pd precursor during formation of the metal phase by hydrogen reduction was investigated by TPRD-mass spectrometry analysis, and the obtained nanoparticles were characterized by CO-DRIFT spectroscopy and HR-TEM microscopy. Butadiene selective hydrogenation to butene, a well known structure-sensitive reaction, was used to test the performances of the systems prepared. Pd/CeO2 catalyst showed the best selectivity to butene with the lowest amount of undesired butane, result ascribable to the morphology of palladium nanoparticles.