Effect of the State of a Surface Layer on the Properties of Pd–P Catalysts in the Hydrogenation of Alkylanthraquinones

Abstract

X-ray photoelectron spectroscopy (XPS) was used to study the state of the surface layer of a Pd–P catalyst, which exhibits high selectivity in the hydrogenation of 2-ethyl-9,10-anthraquinone. The preparation of the catalyst from Pd(acac)₂ and white phosphorus in hydrogen in a toluene–1-octanol solution led to the formation of Pd–P nanoparticles whose surface was enriched in electron-deficient palladium, apparently, as a constituent of an amorphized 2D layer based on a solid solution of Pd and P. Octyl esters of phosphoric acids, adsorbed on the surface, acted as stabilizers. A relationship between the properties of the Pd–P catalyst in the hydrogenation of 2-ethyl-9,10-anthraquinone and the state of the surface layer was considered.