Development of Ultrafine Active Supported Metal Catalyst by Chemical Vapor Deposition

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Development of ultra fine active supported Metal Catalyst by Chemical vapor phase deposition is devided three parts by the research context.The first step: Ni/SiO_2 catalyst was prepared by decomposition of fume d Ni(NO_3)_2 from which was sprayed its methanol solution. The NiO particle of the catalyst is finely reduced to 300-500A in size. It was found that the catalyst is highly active than ordinary prepred impregnated catalyst by testing a methanation of carbon monoxide as a model reaction In order to promote the activty, the particle size of nickel oxide should be more reduced, but the nickel particle than 300-500A can not be prepared in this step.The Second step: So Vaporized NiCl_2 was used as a Ni source, but in th is method, Cl_2 which is produced by the oxidation of SiCl_4 and NiCl_2 inhibited the oxidation of SiCl_2 and Nicl_2 and unreacted NiCl_2 so retards adsorption of hydrogen that catalytic activity is depressed. To remove this defect.The third step: Adding the water vapor to this reaction, produced Cl_2 is removed by formation of HCl. By this improvemen, the extent of the conversion to NiO was quantitatively facilated. The Supersaturation vapor pressure of NiO is enhanced than the first step, and it becomes to produce smaller particle till 100A. In spite of no difference between the particle size of nickel oxide and ordinary impregnated catalysts, the catalystic activity is higher than theordinary catlysis. The reason could be deduced from the facts that the optimal lattice strain of nickel oxide are 3-4x10^<-3> and the lattices are deform during the rapid quenchingin the preparation. And it is revealed the growth rate of the particlesare controlled by coagulation process of SiO2 and NiO neucleus.It hasbe-come apparent that fundamental items of the catalyst preparation depends on the basis of this Grant-in-Aid for Scientific Research.