Preparation of Carbon-Coated Catalyst Particles -Enhanced Performance by Nano-Structure Control of Carbon Layers Coated-

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The purposes of the present project were (1)establishment of the procedure to control adsorptivity of carbon layers coated on the particles of catalysts by modifying their nano-structure and (2)enhancement of catalyst performance and/or creation of new catalytic phases or new catalytic functions The following results were obtained.1.Nano-structure control of carbon layers coatedCarbon layers formed on catalyst particles of oxides were proved to be rich in nano-sized pores from detailed analysis of pore structure on carbon isolated from carbon-coated MgO particles. Pore structure of nano-sized range depended strongly on the substrate oxides, such as α-Al_2O_3,γ-Al_2O_3,TiO_2,etc., and also on the carbon precursors, such as poly (vinyl alcohol), hydroxyl propyl cellulose, poly (ethylene terephthalate), etc. Through the hydrolysis of titanium isopropoxide in aqueous solution of poly (vinyl alcohol) followed by heat treatment at a high temperature, fine particles of carbon-coated TiO_2 par … More ticles were obtained with a high efficiency in usage of materials in preparation process and also with high performance as photocatalysts.2.Enhancement of performance by interaction between coated carbon and substrate oxidesCarbon coated on oxide particles was found to interact with the substrate oxide to give reduced phases. Through carbon coating of TiO_2 particles, one of the reduced phases, Ti_4O_7,was formed. This reduced phase Ti_4O_7 was found to have photocatalytic activity.Through the heat treatment of the mixtures of SnO_2,MgO and poly (vinyl alcohol) at a high temperature, carbon-coated Sn powders were successfully prepared. MgO particles was found to hinder the coagulation of metallic Sn just after the reduction of SnO_2 by the interaction with carbon at a high temperature, and also to leave open spaces neighboring fine particles of Sn metals after dissolution by diluted acid. Carbon-coated Sn thus prepared showed high performance as anode of lithium ion rechargeable batteries. Carbon coated on Sn could avoid the coagulation during charge-discharge cycles in batteries. Less