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

Recently, 8-membered ring zeolites and zeotype materials have attracted much attention in the expectation of selective catalysis due to their small pores; e.g., they could be good catalysts with high selectivity for lower olefins in the methanol to olefins (MTO) reaction. We have possessed interests in the RTH-type zeolites because they have two-dimensional 8- membered ring channels and also cages that can accommodate reaction intermediates. However, since the discovery of this zeolite, intensive studies on the synthesis and application have not been done because the original synthesis method is based on the use of expensive and elaborated organic structure-directing agents (SDAs). Therefore, the preparation of various metallosilicates, the development of organic-SDAs-free synthesis route and their catalytic applications have been hardly achieved.

Here, we report the synthesis of metallosilicates with an RTH-topology by using the organic SDAs according to the original procedure with modifications. Furthermore, an organic-SDAs-free synthesis route to the RTH-type zeolites has been newly developed. The addition of the RTH-type zeolite as seeds into the mother gel was essential to the organic-SDAs-free synthesis.