Direct H2-to-H2O2 oxidation in aqueous acidic medium containing Br promoter over Pd/Al2O3 and Pd/C catalysts thermally pretreated under different conditions

Influence of thermal pretreatments (under N2, air or H2 gas atmosphere at 500 °C or 700 °C) has been investigated for the Pd/Al2O3 and Pd/Carbon catalysts in terms of its effect on their Pd particle size and performance in the H2-to-H2O2 oxidation and H2O2 destruction (by decomposition and/or hydrogenation) reactions in aqueous acidic medium containing Br promoter. The influence on the net H2O2 formation is found to depend strongly upon the catalyst support due to support-Pd cluster interactions. For both the catalysts, the thermal treatments (except in air) caused a large increase in their Pd particle size. The increase in Pd particle size caused an increase in the H2O2 formation activity of Pd/Al2O3 but a decrease in the H2O2 formation activity of Pd/C