Hydrogenation of acetylene alcohols with novel Pd colloidal catalysts prepared in block copolymers micelles

Hydrogenation of the triple bond of acetylene alcohols to the double one of olefin alcohols (linalool, isophytol) was studied with Pd colloids prepared in polystyrene-poly-4-vinylpyridine micelles in toluene and deposited on Al2O3. The high selectivity (99.8% for linalool and 99.5% for isophytol) of such catalyst is explained by durable modification of the Pd nanogarticle surface with 4-vinylpyridine units. The activity of the Pd catalyst studied is determined by high reactivity of small Pd nanoparticles. Maximum relative rate was found to be in methanol, but the highest selectivity was achieved in toluene because the latter is a selective solvent for polystyrene-poly-4-vinylpyridine micelles and provides the better accessibility of reactive sites. (C) 1999 Elsevier Science B.V. All rights reserved.