A comparative study of Pd supported on MCM-41 and SiO2 in the liquid phase hydrogenation of phenyl alkyl acetylenes mixtures

The stereoselective hydrogenation of phenyl alkyl acetylenes at 298 K and atmospheric pressure of hydrogen over Pd-supported catalysts has been studied. The catalysts were prepared by impregnation of MCM-41 and SiO2 with Pd(acac)2 precursor, with metal content close to 1 wt.%. All the solids were characterised by nitrogen adsorption-desorption isotherms at 77 K, TPR, H2 and CO chemisorption, XRD and TEM measurements. Three competitive reaction systems 1-phenyl-1-pentyne/1-phenyl-1-propyne, 1-phenyl-1-pentyne/1-phenyl-1-butyne, 1-phenyl-1-butyne/1-phenyl-1-propyne have been examined. The results show that the competitive reaction results in an increase of the hydrogenation rate for phenyl alkyl acetylene with minor alkyl chain size in all studied systems. The reactions were found to be zero order concerning the alkyne concentration.