Preparation of RTH-type zeolites with the amount and/or kind of organic structure-directing agents (OSDA): Are OSDAs indispensable for the crystallization?

Although the RTH-type borosilicate, [B]-RTH, has been originally synthesized by using 1,2,2,6,6-pentamethylpiperidine (PMP) as organic structure-directing agent (OSDA) in combination with ethylenediamine (EDA), we have established the synthesis method for preparing the RTH-type zeolites without using any OSDAs. To confirm whether the OSDAs is indispensable for this zeolite, the conditions for synthesizing the RTH-type borosilicate have been investigated in detail; the RTH-type borosilicate was synthesized with the amount and/or kind of organic amines varied. First, the effect of the amount of PMP on the crystallization of the [B]-RTH was investigated with the amount of EDA constant. Second, [B]-RTH was synthesized by using diverse amines in place of PMP in the presence of EDA. The effect of the use of OSDAs on the direct incorporation of heteroatoms such as Al, Ga and Fe into the RTH framework was also investigated. Finally, the effectiveness of the use of OSDAs for the RTH-type zeolites in terms of the diversification of the RTH-type zeolite was described.

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► The RTH-type zeolites were synthesized with the amount and/or kind of OSDAs varied.
► The effect of the use of OSDAs on the direct incorporation of heteroatoms into the RTH framework was investigated.
► The use of specific OSDAs is not an essential factor for the formation of the RTH-type zeolite.