The effect of crystallinity on selectivity of palladium catalysts in hydrogenation of 2-ethyl-9,10-anthraquinone

The catalytic properties of palladium crystallites obtained from various precursors were studied in the hydrogenation of 2-ethyl-9,10-anthraquinone. The highest yield of H2O2 (88%) is achieved on unmodified Pd crystallites obtained from Pd(dba)2 at 50 degrees C. A sigmoidal relationship between the coherent domain size (CDS) of Pd particles and the content of anthrones, which are by-products of the eAQ transformation, is established. Small Pd clusters, along with the reduction of eAQ carbonyl groups, accelerate predominantly the hydrogenation of the eAQH(2) aromatic rings. The smallest contribution of the side processes is observed for a palladium catalyst with a CDS of 3-5 nm.