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

本课题的目的是：(1)通过改变催化剂的纳米结构，建立控制其颗粒表面碳层吸附性能的方法；(2)提高催化剂的性能和/或创造新的催化相或新的催化功能。碳包覆层的纳米结构控制通过对碳包覆MgO颗粒分离的碳孔结构的详细分析，证明在氧化物催化剂颗粒上形成的碳层富含纳米孔。α-Al_2O_3、γ-Al_2O_3、TiO_2等基质氧化物对纳米级孔结构的影响较大。，也对碳前体，如聚（乙烯醇），羟丙基纤维素，聚（对苯二甲酸乙酯）等。通过将异丙醇钛在聚乙烯醇水溶液中水解，再进行高温热处理，得到了碳包覆TiO_2粒子，制备过程中材料利用率高，颗粒数量多，且作为光催化剂性能优良。通过涂层碳和基体氧化物之间的相互作用增强性能发现，涂层在氧化物颗粒上的碳与基体氧化物相互作用，产生还原相。通过TiO_2颗粒的碳包覆，形成一种还原相Ti_4O_7。发现该还原相Ti_4O_7具有光催化活性。通过对SnO_2、MgO和聚乙烯醇的混合物进行高温热处理，成功制备了碳包覆锡粉。发现MgO颗粒阻碍了金属锡在高温下与碳相互作用还原后的凝聚，并且在稀释酸溶解后，在金属锡的细颗粒周围留下了开放的空间。所制备的碳包覆锡作为锂离子可充电电池的负极具有良好的性能。碳包覆锡可以避免电池在充放电循环过程中的凝固。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