Borohydride reduction of Al2O3 supported NiCu bimetallic catalysts for the hydrogenation of styrene: study of surface properties

The surface properties of Ni particles can be altered by the addition of a second metal. This influences its catalytic properties. Hence, the surface properties of a series of alumina (Al2O3) supported NiCu bimetallic catalysts prepared via chemical reduction using KBH4 were investigated. They were characterized using H-2-chemisorption, H-2-temperature programmed desorption, H-2-temperature programmed reduction, X-ray diffraction and scanning electron microscopy analysis and tested for the hydrogenation of styrene in liquid phase. In the bimetallic catalysts, Ni and Cu existed as NiCu species or as separate phases. The Ni active sites favored the hydrogenation of styrene to only ethylbenzene. However, the extent of hydrogenation was mainly determined by the types of Ni active sites available on the catalyst which depended on the Cu/Ni ratio. The surface structure of the nickel phase is modified by incorporation of copper.