The role of chemisorbed water in formation and stabilization of active sites on Pd/Alumina oxidation catalysts

Abstract A series of Pd/Al 2 O 3 catalysts with different palladium loading was prepared by incipient wetness impregnation method. As it was shown by various physicochemical methods, palladium at concentrations not exceeding 0.5 wt.% favors to stabilize in an atomic dispersed ionic state. Appearance of PdO phase has been firmly detected by TPR, DR UV–vis and EXAFS starting from Pd concentration of 1 wt.%. It was found that low-content Pd/Al 2 O 3 catalysts are characterized by high activity in CO oxidation due to atomically dispersed palladium species tailored to the donor sites of the support. The presence of chemisorbed water allows one to stabilize Pd in highly disperse state thus preventing the catalyst deactivation.