Stable aluminosilicate zeolites with extra-large pores open through rings of more than 12 tetrahedra are in demand to process molecules larger than those currently manageable. However, until very recently, they proved elusive. Here we report a new strategy based on an interchain expansion design concept that yields thermally and hydrothermally stable silicates by expansion of a one dimensional (1D) silicate chain with an intercalated silylating agent that separates and connects the chains. As a result, new types of zeolites zeolites with extra-large pores delimited by 20, 16, and 16 Si tetrahedra along the three crystallographic directions, respectively, are obtained. The as-made inter-chain expanded zeolite contains dangling Si-CH3 groups that by calcination connect to each other resulting in a true, fully connected 3D zeolite framework with a very low density, just slightly above that of water. Additionally, it features triple four ring units never seen before in any type of zeolite. Ti can be introduced in this zeolite to obtain a catalyst active in the liquid-phase oxidation of bulky alkenes that shows promise in the industrially relevant clean production of propylene oxide using cumene hydroperoxide as an oxidant.
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