Preparation and catalytic properties of single-phase Ni-Sn intermetallic compound particles by CVD of Sn(CH3)(4) onto Ni/silica

The particles of each single-phase Ni-Sn intermetallic compound (IMC), Ni3S n, Ni3Sn2, and Ni3Sn4, have been formed on silica by chemical vapor deposit ion (CVD) of Sn(CH3)(4) onto Ni/SiO2. The prepared Ni-Sn IMC/SiO2 was chara cterized by chemical analysis, X-ray diffraction, temperature-programmed re duction, and X-ray photoelectron spectroscopy. The results clarified that t he particles on silica had the same stoichiometric Ni/Sn atomic ratio and s pecific bulk and surface structure as those of corresponding unsupported IM Cs prepared by melting the mixture of pure Ni and Sn powder. The Ni-Sn IMC/ SiO2 was used as a catalyst for the dehydrogenation of cyclohexane. The cat alytic activity of each Ni-Sn IMC/SiO2 was much higher than that of the uns upported IMCs, whereas it was lower than that of the Ni/SiO2 catalyst. The catalytic activities of Ni-Sn IMCs increased with the increasing Ni/Sn rati o. The selectivity of Ni3Sn/SiO2 and Ni3Sn2/SiO2 for the formation of benze ne was almost 100 C-%, even at higher conversions. The unsupported IMC cata lysts also showed high selectivity to benzene, whereas Ni catalyst gave alm ost exclusively methane at higher conversions. (C) 2001 Academic Press.