日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

In this paper, we focus on the conventional synthesis methods of mesoporous zeolites with precisely controlled nanopore structures, and the recent development and challenges are introduced. Then, our new synthetic method using a nanoporous metal oxide as a template is presented. The precise control of mesopore structures of zeolites is crucial to improve the catalytic performances. The importance of nanostructures has also been demonstrated very recently in zeolite–metal oxide mixed catalysts. Previous studies have shown that nanoporous carbon templates are useful for the control of pore size and structural regularity of mesoporous zeolites. However, hydrothermal synthesis of zeolites using hydrophobic carbon templates is often plagued by the zeolite formation outside the template. We attempted to solve this problem by using a relatively hydrophilic metal oxide as a template. When nanoporous cobalt oxide was used as a template, silicalite-1 was preferentially grown inside the template by the hydrothermal synthesis, giving ordered mesoporous zeolite by the template removal. In contrast, when carbon was used as a template, external precipitation and the formation of small nanoparticles occurred under the same conditions.