Sandwich-type zeolite intergrowths with MFI and the novel extra-large pore IDM-1 as ordered end-members

Stacking faults are two-dimensional planar defects frequently arising in zeolites, modifying their properties and potentially affecting their performance in catalysis and separation applications. In classical zeolite intergrowths, a topologically unique zeolite layer may often pile up after some spatial transformation (lateral translation, rotation, and/or reflection) that may occur in different amounts or directions with about similar probabilities, leading to a difficult to control disorder. Here, we present a new kind of zeolite intergrowth that requires an additional topologically distinct layer rather than a spatial transformation of a unique one. Stacking of the so-called pentasil layers produces the well-known medium pore zeolite MFI. Intercalation in strict alternation of a topologically distinct second layer sandwiched between pentasil layers expands the structure to produce the new extra-large pore IDM-1. Stacking disorder modulates the structural expansion along the stacking direction. The disordered materials have been studied by simulation of the X-ray diffraction patterns using the program DIFFaX and by Cs-corrected highresolution electron microscopy. We show that disorder does not occur at random but in extended domains and can be controlled all the way from MFI to IDM-1 by just varying the concentration of the synthesis mixture.The authors thank funding from the Spanish Ministry of Science, Innovation and Universities, under Projects MAT2015-71117-R (MINECO/FEDER, UE), PID2019-105479RB-I00 and RTI2018-101599-B-C22 (MCUI/AEI/FEDER, UE), the Swedish Research Council (VR), and the Knut and Alice Wallenberg Foundation (KAW). L.A.V. also thanks the Generalitat Valenciana (project PROMETEO/2018/024). A.M. acknowledges the Spanish Ministry of Science (RYC2018-024561-I) and the Regional government of Aragon (DGA E13_20R), the National Natural Science Foundation of China (NFSC-21850410448 and NSFC-21835002), and the Centre for High-resolution Electron Microscopy (CℏEM), supported by SPST of ShanghaiTech University under contract No. EM02161943.Peer reviewe