On the reduction of Pd2+ forms in Pd/γ-Al2O3 catalysts

The influence of the preparation method (i.e., Pd precursor and heat treatments) on the reduction pattern of Pd/γ-Al2O3 catalysts has been investigated by TPR. The role of the Cl− ions and the effect of metal dispersity on the stability of Pd catalysts reduced at different Tr (400≤Tr≤800°C) have been discussed. Reoxidation of Pdo occurs during exposure to the atmosphere and the formation both of easily reducible “PdO forms” and “Cl-containign Pd2+ oxo-complexes”, strongly interacting with alumina surface, has been pointed out.