SYNERGISTIC EFFECT IN CATALYTIC-SYSTEMS TC-ME SUPPORT (ME = PT, PD, PH, RU, OR NI)/

A large series of supported bimetallic catalysts Tc-Me/support (Me = P t, Pd, Ph, Ru, or Ni; support is gamma-Al2O3, MgO, TiO2, Y2O3, SiO2, o r C) are prepared and studied. The content of deposited metal varied w ithin 0.1-1%. The activity of bimetallic samples in dehydrogenation an d dehydrocyclization of hydrocarbons increases nonadditively as compar ed to the monometallic systems. The extent of the synergistic effect d epends on the ratio between the amounts of deposited metals and on the nature of support. To elucidate the mechanism of synergistic effect, the state of the catalyst surface was studied by a set of physicochemi cal methods: chemisorption of H-2 and CO, temperature-programmed reduc tion, UV-visible diffuse reflection spectroscopy, IR spectroscopy of a dsorbed CO, and electron microscopy. It is concluded that the synergis m is mainly due to formation of compounds TcxMey (Me = Pt, Pd, Ph, Ru, or Ni).