Selective deposition of palladium onto supported nickel - bimetallic catalysts for the hydrogenation of crotonaldehyde

Alumina supported nickel palladium bimetallic catalysts were prepared by a selective redox deposition method and used for the hydrogenation of crotonaldehyde. Supported nickel catalysts, prepared by incipient wetness, were reduced to form a nickel hydride surface prior to contact with palladium(II) salt solutions. Palladium was successfully deposited selectively onto the nickel hydride surfaces, by a redox reaction. Catalysts were prepared using two different palladium(II) salt solutions; (a) pH 1 palladium chloride in hydrochloric acid solution or (b) pH 3 palladium nitrate in nitric acid. The deposition of palladium onto the supported nickel nanoparticles was strikingly different when using the two palladium solutions, with strong alloy formation with the pH 1 solution and a weaker segregated nickel palladium catalyst with the pH 3 solution. Both catalysts were compared with monometallic palladium and nickel supported catalysts for the hydrogenation of crotonaldehyde with the sample prepared at pH 1 being more active