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Development of novel solid acid catalyst based on polyanion nanosheets

基于聚阴离子纳米片的新型固体酸催化剂的研制

基本信息

批准号：
15360427
负责人：
HARA Michikazu
金额：
$ 9.54万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Two-dimensional metal oxide sheets in cation-exchangeable layered metal oxides such as HTiNbO_5 and HNb_3O_8 were examined as solid-acid catalysts. Exfoliation of HTiNbO_5 and HNb_3O_8 in aqueous solutions formed colloidal single-crystal TiNbO_5 and Nb_3O_8 nanosheets, precipitating under an acidic condition to form aggregates of the nanosheets. Although esterification of acetic acid, cracking of cumene and dehydration of 2-propanol were not catalyzed by original layered metal oxides because of the narrow interlayer distance, which prevents the insertion of organic molecules, the nanosheet aggregates functioned as strong solid acid catalysts for the reactions. NH_3 temperature-programmed desorption and ^1H magic-angle spinning nuclear magnetic resonance spectroscopy revealed that these nanosheet aggregates have strong Bronsted acid sites due to Nb^<5+> (or Ti^<4+>)-(OH)-Nb^<5+>.We also found that amorphous carbon composed of small graphen sheets with high density of sulfonic acid groups function as a replacement for sulfuric acid catalyst. The material prepared from inexpensive starting materials has high thermal and chemical stability.

本文研究了阳离子可交换层状金属氧化物HTiNbO_5和HNb_3O_8中的二维金属氧化物片作为固体酸催化剂。HTiNbO_5和HNb_3O_8在水溶液中的剥离形成胶体单晶TiNbO_5和Nb_3O_8纳米片，在酸性条件下沉淀形成纳米片的聚集体。虽然乙酸的酯化，异丙苯的裂解和2-丙醇的脱水没有被原来的层状金属氧化物催化，因为窄的层间距，这阻止了有机分子的插入，纳米片聚集体作为强固体酸催化剂的反应。NH_3程序升温脱附和^1H魔角自旋核磁共振谱表明，这些纳米片聚集体中存在着由Nb^<5+>（或Ti^<4+>）-（OH）-Nb^<5+>形成的强的B酸中心，同时还发现了由具有高密度磺酸基的小石墨烯片组成的无定形碳可以替代硫酸催化剂。由廉价的起始材料制备的材料具有高的热稳定性和化学稳定性。