A promoting effect of dilution of Pd sites due to gold surface segregation under reaction conditions on supported Pd–Au catalysts for the selective hydrogenation of 1,5-cyclooctadiene.

Restructuration of AuPd/CeO 2 catalysts is observed during 1,5-cyclooctadiene hydrogenation, with gold surface segregation in which gold acts as a diluent of Pd surface sites. The composition of the catalyst influences the catalytic behavior, and an optimum is observed at a Pd/Au molar ratio of 0.13, as determined by X-EDS STEM. Pd–Au/CeO 2 shows higher hydrogenation rates (11.2 × 10 −5 mol/g s) versus the unpromoted Pd/CeO 2 catalysts (1.7 × 10 −5 mol/g s), and the Pd/TiO 2 (7.5 × 10 −5 mol/g s) catalysts used as conventional hydrogenation catalysts. Since the active sites are generated under reaction conditions, characterization of the catalysts after quenching the reaction at specific reaction times was required. [ABSTRACT FROM AUTHOR]