The structure sensitivity of acetylene hydrogenation on catalysts with controlled shape of palla dium nanoparticles was studied. Palladium particles of cubic (Pd cub ), cuboctahedral (Pd co ) and octahedral (Pd oct ) shapes were obtained by a colloidal method. Poly(N vinyl)pyrrolidone (PVP) was used as the stabi lizer of colloidal solutions. In order to eliminate the effect of the polymer on the properties of the catalyst, PVP was removed from the surface of the particles after their transfer to the support by simultaneous treat ment with ozone and UV radiation. This allowed complete cleaning of the catalyst surface from the organic stabilizer without any change in the morphology of particles. The effectiveness of this treatment method was confirmed by X ray photoelectron spectroscopy and scanning electron microscopy. It was found experimen tally that the shape of nanoparticles does not influence the catalyst selectivity, but the activity decreases in the order Pd oct > Pd co > Pd cub . Since octahedrons consist of (111) faces, the cubes contain only (100) faces, and the cuboctahedrons are composed of faces of both types, Pd 111 is more active than Pd 100 . Calculations with the use of a statistical method showed that the ~3 nm Pd octahedrons are nanoparticles with optimum shape and size, giving maximum catalyst activity.

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