Characterization and catalytic behaviour of graphite lamellar compounds of iron, nickel and cobalt

Abstract

Several kinds of metal-graphite lamellar compounds were characterized by XRD, XPS and SEM and thermogravimetrics techniques. The catalytic behaviour of these catalysts was also studied. The FeCl 3-graphite lamellar compound was not reduced to the metallic state by hydrogen until the lamellar structure had been partially destroyed, yielding free FeCl 3. The hydrogen-treated catalyst was not active for ethylene hydrogenation. A catalyst (Ni-Graphimet) prepared from NiCl 2-GC lamellar compound was proved to have no lamellar structure but to contain Ni metal particles with graphite. The activity (turnover frequency) of ethylene hydrogenation over Ni-Graphimet was the same as that over Ni supported on graphite catalyst (Ni/GC), but was much lower than that over Ni/SiO 2. The binding energies of Ni 2 P3/2 of Ni-Graphimet and Ni/GC catalysts were 0.4 eV higher than that of Ni/SiO 2 in their reduced states. Co(0) intercalated in the graphite layer prepared by a reported method was active for ethylene hydrogenation and dimerization. However, the catalytic behaviour of lamellar compounds of Co(0)-GC was different from that of the Co metal phase supported on graphite. The nature of the active site is discussed.