Optimized palladium catalyst systems for the selective liquid-phase hydrogenation of functionalyzed alkynes

Silica-supported palladium catalysts for the selective liquid-phase hydrogenation of alkynes to alkenes were prepared. As a model reaction the hydrogenation of 3-methyl-1-pentyn-3-ol was chosen. The kinetics of this reaction were investigated. Different approaches were used to obtain an optimal catalyst system. The selectivity of the palladium catalysts was successfully improved by modifying the catalyst with copper and the effect of this modification on the reaction mechanism was studied. The addition of quinoline as a reaction modifier to the system was investigated as a manner to improve selectivity. Monolith supported catalysts were prepared to obtain a more convenient reactor configuration. (C) 2002 Elsevier Science B.V. All rights reserved.