Effects of Phosphorus Modifier and Support on the Properties of Palladium Catalysts in the Chemoselective Hydrogenation of Acetylenic Compounds

Efficient heterogeneous catalysts for chemoselective hydrogenation of terminal and disubstituted alkynes and alkynols to monoenes based on Pd–P particles have been proposed. The influence of a zeolite support (Na-ZSM-5, MSM-41) and a phosphorus modifier on the properties of palladium catalysts in the semihydrogenation of acetylenic compounds is considered. Promotion with phosphorus increases the activity of palladium catalysts in hydrogenation of various acetylenic compounds 2.5- to 30-fold without reducing the selectivity for monoenes. The high selectivity for monoenes is determined by both thermodynamic and kinetic factors. The possibility of changing the ratio of the rates of hydrogenation of triple and double bonds by varying the nature of the solvent and the structural order of the catalyst particles was demonstrated using hydrogenation of acetylenic alcohols as an example.