Preparation of Highly Active Ceramics Catalysts by Chemical Vapor Deposition for Catalytic Combustion

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In catalytic combustion processes, development of highly active and thermally stable ceramics catalyst is desired. In the present study, the preparations of supported mixed oxide catalysts mainly by Chemical Vapor Deposition (CVD) and Chemical Liquid Deposition (CLD) methods were tried. The results are summarized as follows :(1) Highly Dispersed LaCoO_3/ZrO_2 prepared by Chemical Liquid Deposition (CLD)LaCoO_3 highly dispersed ZrO_2 was prepared by impregnating ZrO_2 with aqueous solutions of the mixtures of La and Co acetates. The high dispersion was confirmed by IR, XRD, and TEM. This catalyst showed a very high catalytic activity for complete oxidation of propane.(2) Vanadium Oxide This Film Catalysts Prepared by CVDHighly dispersed vanadium oxide overlayers were formed on SiO_2 by CVD of VO (c_2H_5)_3 as was confirmed by XPS and XRD. Furthermore, EXAFS and XANES analyses revealed that the V_2O_5 were present as thin films. This catalyst was much more active than V_2O_5 prepared by an impregnation method for oxidative dehydrogenation of a alcohol.(3) Highly Active CoO_X Dispersed on ZrO_2 Prepared by Low-Temperture Oxygen plasmaCo (OCOCH_3)_2 dispersed on ZrO_2 was treated with oxygen which was activated in Ar-plasma.It was confirmed by infrared spectroscopy that all Co (OCOCH_3)_2 were changed to CoO_X by this treatment. This catalyst showed activities for the complete oxidation of propane much greater than Pt/Al_2O_3 and La_<0.8>Sr_<0.2>coO_3 which were reported to be excellent oxidation catalysts.These results demonstrate that CLD, CVD and utilization of oxygen-plasma were superior methods to prepare oxide-thin films on supports, which posses high catalytic performance for the catalytic combustion.