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

本项目的目的是(1)建立通过改变催化剂的纳米结构来控制包覆在催化剂颗粒上的碳层的吸附能力的方法；(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。1.包覆碳层的纳米结构控制通过详细分析从碳包覆的氧化镁颗粒中分离出的碳的孔结构，证明在氧化物催化剂颗粒上形成的碳层具有丰富的纳米孔。纳米级的孔结构强烈依赖于基质氧化物α-Al_2O_3、γ-Al_2O_3、TiO_2等，也依赖于碳前驱体聚乙烯醇、羟丙基纤维素、聚对苯二甲酸乙二酯等。通过异丙醇钛在聚乙烯醇水溶液中的水解，再经高温热处理，得到了细小的碳包覆TiO_2 PAR…涂层碳与基质氧化物之间的相互作用增强涂层碳与基质氧化物颗粒之间的相互作用发现，涂层碳与基质氧化物相互作用，得到了还原的相。通过对二氧化钛颗粒进行碳包覆，生成了还原相Ti4O7。该还原相Ti4O7具有光催化活性。通过对SnO2、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的锡粉。结果表明，氧化镁颗粒在高温下与碳相互作用，在SnO2还原后立即阻碍金属锡的凝聚，并在稀酸溶解后，在金属锡细小颗粒周围留下空隙。用这种方法制备的碳包锡作为锂离子二次电池的负极具有良好的性能。在锡表面涂覆碳可以避免电池在充放电循环过程中的凝结。较少

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