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

本项目的目的是（1）建立通过改性催化剂颗粒的纳米结构来控制涂覆在催化剂颗粒上的碳层的吸附性的程序和（2）增强催化剂性能和/或产生新的催化相或新的催化功能。碳层涂覆的结构控制通过对从碳涂覆的MgO颗粒分离的碳上的孔结构的详细分析，证明了在氧化物催化剂颗粒上形成的碳层富含纳米尺寸的孔。纳米尺度的孔结构强烈依赖于基体氧化物，如α-Al_2 O_3，γ-Al_2 O_3，TiO_2等，通过异丙醇钛在聚乙烯醇水溶液中的水解反应和高温热处理，制备了碳包覆TiO_2微粒 关于我们 2.包覆碳与基质氧化物的相互作用对催化剂性能的增强研究发现包覆在氧化物颗粒上的碳与基质氧化物相互作用产生还原相。通过碳包覆TiO_2颗粒，形成还原相之一Ti_4O_7。通过对SnO_2、MgO和聚乙烯醇的混合物进行高温热处理，成功地制备了碳包覆Sn粉。MgO颗粒在高温下与碳的相互作用阻碍了SnO_2还原后金属Sn的凝聚，并在稀酸溶解后在Sn金属微粒附近留下空隙。由此制备的碳包覆锡显示出作为锂离子二次电池负极的高性能。碳包覆在锡上可以避免电池在充放电循环过程中的凝结。少

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