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The transformation from a disordered into an ordered version of the zeolite natrolite occurs on prolonged heating of this material in the crystallizing medium, but not if the mother liquor is replaced by water or an alkaline solution. This process occurs for both aluminosilicate and gallosilicate analogues of natrolite. In cross experiments, the disordered Al-containing (or Ga-containing) analogue is heated while in contact with the mother liquor of the opposite analogue, that is, the Ga-containing (or Al-containing) liquor. Therefore, strong evidence for the mechanism of the ordering process was obtained, which was thus proposed to proceed by intraframework migration of tetrahedral atoms without diffusion along the pores. Migration is first triggered, then fuelled by surface rearrangement through reactions with the mother liquor, and stops when an almost fully ordered state is attained. Classical dissolution-recrystallization and Ostwald ripening processes do not appear to be relevant for this phase transformation. [ABSTRACT FROM AUTHOR]

HPM‐16 is a highly porous germanosilicate zeolite with an interrupted framework that contains a three‐dimensional system of 12+10×10(12)×12+10‐membered ring (MR) pores. The 10(12) MR pore in the b direction is a 10 MR pore with long 12 MR stretches forming 30 Å long tubular supercages. Along one direction the 10 MR pores are fused, meaning that the separation between adjacent pores consists of a single tetrahedron that is, additionally, connected to only three additional tetrahedra (a Q3). These fused pores are thus decorated by T‐OH groups along the whole diffusion path, creating a hydrophilic region embedded in an otherwise essentially hydrophobic environment. The structure is built from highly porous 12×12×12 MR uninterrupted layers that are connected to each other through Q3 producing a second system of 10×10×10 MR pores. This zeolite can be extensively degermanated yielding a material with high thermal stability, despite its interrupted nature. [ABSTRACT FROM AUTHOR]

HPM‐14 is a new extra‐large pore zeolite synthesized using imidazolium‐based organic structure‐directing agents (SDAs), fluoride anions, and germanium and silicon as tetrahedral components of the framework. Owing to the presence of stacking disorder, the structure elucidation of HPM‐14 was challenging, and different techniques were necessary to clarify the details of the structure and to understand the nature of the disorder. The structure has been solved by three‐dimensional electron‐diffraction technique (3D ED) and consists of an intergrowth of two polymorphs possessing a three‐dimensional channel system, including an extra‐large pore opened through windows made up of sixteen tetrahedral atoms (16‐membered ring, 16MR) as well as two additional sets of odd‐membered (9MR) and small (8MR) pores. The intergrowth has been studied by scanning transmission electron microscopy (Cs‐STEM) and powder X‐ray diffraction simulations (DIFFaX), which show a large predominance of the monoclinic polymorph A. [ABSTRACT FROM AUTHOR]

IDM‐1 is a new silica zeolite with an ordered and well‐defined framework constructed by alternating pentasil layers and interrupted layers, giving rise to an intersecting system of straight medium pores and undulating extra‐large lobed pores. This unique structure was solved by rotation electron diffraction and refined against synchrotron powder X‐ray diffraction data. Despite the presence of both Si(OSi)3(OH) and Si(OSi)2(OH)2 sites, this new zeolite presents high thermal stability, withstanding calcination even to 1000 °C. The location of defects at specific sites of the structure results in alternating hydrophobic SiO2 and hydrophilic SiO(2−x)(OH)2x intracrystalline regions. This peculiar combination of intersecting medium and extra‐large pores and alternating regions of different chemical character may provide this zeolite with unique catalytic properties. [ABSTRACT FROM AUTHOR]