Preparation of Nickel Catalyst Supported on Ultra Fine Titania Particles

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The preparation of ultra fine titania particles was carried out by the decomposition of titanium tetraisopropoxide(TTIP) in gas phase. The mean diameter and surface area of the particles were strongly dependent upon the preparation conditions, that is, high temperature, high TTIP concentration and long residence time in a reactor resulted in large particle size and small surface area. The smallest size of titania particle was around 15 nm and it was almost coincided the value calculated from the surface area, measured from nitrogen adsorption method. The result indicated that the surface area was regarded as outer surface area and the particles did not have a micro pore.The nickel catalyst supported on the ultra fine particles was prepared with impregnation method and CVD method. Furthermore, the gas phase hydrogenation of benzene was carried out over the nickel catalysts. The hydrogenation activity was proportional to the surface area of the ultra fine titania, even though the catalys … More t had the same nickel contents. The result suggested that nickel was well dispersed on the titania with large surface area. Although the nickel content of the catalyst prepared by CVD method was lower than that of impregnated ca talyst, the turn over frequency of the former was larger than that of the latter. This result implied that nickel catalyst with high dispersion could be prepared by a CVD method.The hydrogenation of methyl oleate was carried out in a batch reactor at an atmospheric pressure. The nickel catalysts prepared by the impregnation method and CVD method were dispersed in the solution contained methyl oleate, and hydrogen with constant flow rate was supplied in the solution. The catalytic activity and selectivity to methyl stearate were examined over the catalysts. The selectivity over the catalyst prepared by CVD method was higher than that over the catalyst prepared from impregnation method. However, the reaction was carried out over the catalyst supported on alumina with large pore volume, the selectivity to methyl stearate significantly decreased. Furthermore, the catalytic deactivation of alumina supported catalyst was larger than that supported on the titania prepared from the CVD method. It was considered that the further decomposition over nickel active sites in the micro pore on the alumina would decrease the selectivity.The ultra fine titania particles prepared by the CVD method was useful as a catalyst support for the reaction with large heat of reaction Less