The Effect of Particle Size and the Modifier on the Properties of Palladium Catalysts in the Synthesis of Hydrogen Peroxide by the Anthraquinone Method

The effect of the composition of the catalytic system and the size of particles on the properties of palladium catalysts in 2-ethyl-9,10-anthraquinone hydrogenation was studied. It was shown that, depending on the nature of a reducing agent (H₂, AlEt₃), palladium species formed in the absence of a modifying agent catalyze various side processes to a substantial extent together with 2-ethyl-9,10-anthraquinone hydrogenation: mostly hydrogenolysis (in the case of H₂ as a reducing agent) and hydrogenation of aromatic rings in 2-ethyl-9,10-anthrahydroquinone (in the case of AlEt₃ as a reducing agent). Elementary phosphorus was found to have a promoting effect on the selectivity of palladium catalysts in the synthesis of hydrogen peroxide by the anthraquinone method. The main factors that make it possible to control the selectivity of palladium catalysts were discussed.