Solvent‐Free Thermal Synthesis of Extra‐Large‐Pore Aluminophosphate Zeotype via Self‐Assembly of Double‐Four‐Ring Unit

The use of Ge as framework atom to direct the formation of double‐four‐ring (d4r) unit is an effective way to prepare zeolite with extra‐large pores, which however also brings about serious problems with regard to production cost and structure stability for their practical application. A new solvent‐free thermal synthesis strategy is presented here for facile preparation and molecular‐level mechanism study of extra‐large‐pore aluminophosphate zeotype DNL‐1 with ‐CLO structure. For the first time, the formation of intermediate d4r in the induction period was successfully confirmed, and was correlated with the synthesis condition of low water content and quaternary ammonium template with suitable alkyl chain length. The self‐assembly pathway via d4r to form lta, afterwards clo and super cages was further revealed. This work shed light on the rational synthesis of Ge‐free extra‐large‐pore zeotypes based on d4r route. A simple solvent‐free thermal synthesis method was developed to prepare extra‐large‐pore aluminophosphate zeotype DNL‐1, unravelling its crystallization process via self‐assembly of d4r unit, an intermediate formed at synthesis conditions of low water content in presence of a template structure with alkyl chains of proper length. This new synthesis strategy is suitable for rational preparation of d4r‐containing extra‐large‐pore zeolitic materials in the absence of Ge.