Zeolites with Pores Beyond the 12-MR

For obvious catalytic reasons, synthesis of large-pore zeolites has been sought. 14-, 18-, 20-, and even 24-MR materials have been made with different T atoms in the framework [181]. Unfortunately, most of the materials show monodimensional pores and limited stability in catalytic conditions. Aluminophos-phates with 14-MR and 18-MR, denoted as AIPO4-8 (AET) [182] and VPI-5 (VFI) [183] have been synthesized with di-propylamine as pore-filling agent. 

In most cases, SDAs are being used that are not commercially available. Moreover, the detailed catalytic potential of such materials remains unknown at this time. Sometimes such materials, viz. CIT-5, exhibit lower activity than standard zeolites [187]. 

Large-pore materials with other T-atom composition, viz. the galliumphos-phate 20-MR cloverite (CLO) [188] and JDF-20 [189] have an interrupted framework with low thermal stability. The 18-MR galliumsilicate ECR-34 (ETR) [190] is of potential interest for catalysis. Recently developed germanates with intersecting 12- and 14-MR, denoted as ITQ-15 [191] and IM-12 [192] also have potential catalytic interest. 

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