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

Interzeolite conversion, hydrothermal conversion of one zeolite into another, was investigated by the use of FAU type zeolites with different Si/Al ratios as the starting material in the presence of a variety of structure-directing agents (SDAs) under various synthesis conditions. As compared to amorphous materials, the use of FAU type zeolite showed a short induction period and a fast crystallization rate. These results suggest that the dissolution of FAU type zeolite with a specific SDA provides locally ordered aluminosilicate species (zeolitic fragments, nanoparts) that assemble and evolve into the particular zeolite framework. The presence of such nanoparts was confirmed by analyzing mesoporous products which were prepared from the intermediate phases involved in the hydrothermal conversion of FAU type zeolite into ^*BEA type zeolite in the presence of cetyltrimethylammonium cations. We succeed in synthesizing 6 kinds of zeolites of MTN, RUT, ^*BEA, CHA, LEV, and OFF type zeolites with different frameworks so far. It became clear that under milder synthesis conditions, we can synthesize zeolites such as CHA and LEV type zeolites, whose framework structures are similar to that of FAU type zeolite.