Nicolas Bats

Structure orienting role of germanium in zeolite synthesis

Abstract This paper deals with the synthesis results obtained from pure silica and (Si, Ge) systems in presence of hexamethonium cations, Kryptofix2,2,2 and 5-azoniaspiro[ [4] , [5] ]decane derivative cations as organic structure directing agents (OSDA) in hydroxide or fluoride media. The obtained new materials Mu-31, IM-9, IM-10 (UOZ), IM-11(LTA), IM-12 (UTL) all contain D4MR units, confirming the orienting effect of the germanium and/or the fluoride anions towards this small cage. Surprisingly, the extra-large pore IM-12 zeolite could not be obtained in the fluoride medium.

Recent developments in the use of hexamethonium salts as structure directing agents in zeolite synthesis

Abstract Hexamethonium salts are well known as structure directing agents in zeolite synthesis. Usually, hexamethonium bromide is used in alkaline medium to give zeolite EU-1 (EUO structure-type) or ZSM-48 (no structure-type). A new method of synthesis which consists in using organic precursors of the hexamethonium cation for the preparation of EU-1 zeolite will be described. The present paper also reports the use of hexamethonium dihydroxide in fluoride media which allowed the formation of a ZSM-48 type-material and of 2 new zeolites. The structure of the latter display D4R (double four-membered-ring) cages with F− ions occluded inside. IM-7 zeolite is identical to ITQ-13 zeolite recently published by Corma et al [9], whereas the silicogermanate or germanate IM-10 zeolite corresponds to a new topology.