Chemical route to prepare nickel supported on intermetallic TiSiNi nanoparticles catalyzing CO methanation.

In this study, ternary intermetallic nickel silicide, TiSiNi, nanoparticles with a high surface area of 37.5 m g were chemically prepared from SiO-impregnated oxide precursors, which were reduced at as low as 600 °C by a CaH reducing agent in molten LiCl, resulting in the formation of single-phase TiSiNi with a nanosized morphology. The intermetallic TiSiNi phase in the nanoparticles was stabilized in air by surface passive oxide layers of TiO-SiO, which facilitated the handling of the nanoparticles. Considering our previous successful work of preparing single-phase LaNiSi (39.3 m g) and YNiSi (27.0 m g) nanoparticles in a similar manner, the proposed chemical method showed to be a versatile approach in preparing ternary silicide nanoparticles. In this study, we applied the obtained TiSiNi nanoparticles as catalyst supports in CO methanation. The supported nickel catalyst showed an activation energy of 56 kJ mol, which is half as low as that of common TiO-supported nickel catalysts. Also, Ni/TiSiNi provided the lower activation energy more than any previous Ni-based catalyst. Since the measured work function of TiSiNi (4.5 eV) was lower than that of nickel (5.15 eV), it was suggested that the TiSiNi support can accelerate the rate-determining step of C-O bond dissociation in CO methanation due to its good electron donation capacity.