Synthesis of pure polymorph C of Beta zeolite in a fluoride-free system

Pure polymorph C (denoted ITQ-17) resulting from the intergrowth of zeolite Beta has been synthesized in the presence of Ge from a fluoride-free synthesis mixture; this shows that fluoride is not necessary to obtain structures containing D4MR units that were believed to be stabilised by fluoride; on the other hand, the presence of Ge directs the synthesis towards the formation of pure polymorph C.