Catalysis Today, Vol.352, 270-278, 2020
Direct synthesis of H2O2 over acid-treated Pd/C catalyst derived from a Pd-Co core-shell structure
Although a wide range of Pd/C catalysts has been developed for the direct synthesis of H2O2, low H2O2 yields remain a challenging issue. In this study, we propose a novel catalyst design involving the formation of Pd@Co (BO3)(2) core-shell nanoparticles (NPs) on an activated carbon support followed by the cobalt borate shell etching with H3PO4. The non-noble metal shell efficiently suppressed unfavorable aggregation of Pd NPs, resulting in the formation of small and monodisperse Pd NPs after stripping the cobalt. The use of H3PO4 was also beneficial to obtain a high H2O2 yield by decreasing the metallic nature of Pd and enabling the acid-treated activated carbon to act as a solid acid support. The features of the acid-treated Pd/C catalyst derived from the Pd@Co(BO3)(2) core-shell were superior enough for achieving extremely high activity in the direct synthesis of H2O2. The H2O2 productivity of 5721 mmol-H2O2/g-Pd.h with 88.1% H2O2 selectivity reported herein is one of the best values among Pd/C catalysts developed to date. It was also demonstrated that the cobalt borate shell should be completely removed because cobalt accelerated H2O2 decomposition and hydrogenation.