Structure and properties of bimetallic colloids formed in polystyrene-block-poly-4-vinylpyridine micelles: Catalytic behavior in selective hydrogenation of dehydrolinalool

Catalytic properties of palladium and bimetallic (PdAu, PdPt, and PdZn) nan oparticles formed in block copolymer micelles derived from polystyrene-bloc k-poly-4-vinylpyridine (PS-b-P4VP) were studied in dehydrolinalool (DHL) hy drogenation. FTIR spectroscopy on CO adsorption and XPS show that the secon d metal (Au, Pt, or Zn) acts as a modifier toward Pd, changing both its ele ctronic structure and its surface geometry. In turn, this change provides h igher catalytic activity of bimetallic particles formed in PS-b-P4VP micell es compared to Pd micelles, which can be ascribed mainly to an increase in the number of active centers on the particle surface. High selectivity of D HL hydrogenation (99.8% at 100% conversion) was achieved for all the Pd and bimetallic micellar catalysts, by chemical modification of the nanoparticl e surface with pyridine units. Kinetic study of DHL hydrogenation, along wi th computational kinetic models, allowed us to describe a hydrogenation mec hanism with these catalysts. (C) 2000 Academic Press.