THERMOGRAVIMETRIC STUDY OF CARBONACEOUS DEPOSITS ON NICKEL-CATALYSTS PHYSICALLY MIXED WITH AN UNREDUCIBLE OXIDE

NiO physically mixed with an unreducible oxide such as MgO, SiO2 and a lpha-Al2O3 showed high activity in the formation of carbonaceous depos its after the reduction of NiO in a CH4 stream. When the stream was sw itched to C0(2), the entire Ni was oxidized again to NiO after the rem oval of the deposits, though the entire Ni involved in a pure NiO or i n a supported Ni/MgO was not oxidized. The size of Ni particles formed in these mixtures was less than 10 nm in diameter.