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.