The synthesis of crystalline molecular sieves with pore dimensions that fill the gap between microporous and mesoporous materials is a matter of fundamental and industrial interest. The preparation of zeolitic materials with extralarge pores and chiral frameworks would permit many new applications. Two important steps in this direction include the synthesis of ITQ-33, a stable zeolite with 18 x 10 x 10 ring windows, and the synthesis of SU-32, which has an intrinsically chiral zeolite structure and where each crystal exhibits only one handedness. Here we present a germanosilicate zeolite (ITQ-37) with extralarge 30-ring windows. Its structure was determined by combining selected area electron diffraction (SAED) and powder X-ray diffraction (PXRD) in a charge-flipping algorithm. The framework follows the SrSi(2) (srs) minimal net and forms two unique cavities, each of which is connected to three other cavities to form a gyroidal channel system. These cavities comprise the enantiomorphous srs net of the framework. ITQ-37 is the first chiral zeolite with one single gyroidal channel. It has the lowest framework density (10.3 T atoms per 1,000 A(3)) of all existing 4-coordinated crystalline oxide frameworks, and the pore volume of the corresponding silica polymorph would be 0.38 cm(3) g(-1).

The discovery of new materials for separating ethylene from ethane by adsorption, instead of using cryogenic distillation, is a key milestone for molecular separations because of the multiple and widely extended uses of these molecules in industry. This technique has the potential to provide tremendous energy savings when compared with the currently used cryogenic distillation process for ethylene produced through steam cracking. Here we describe the synthesis and structural determination of a flexible pure silica zeolite (ITQ-55). This material can kinetically separate ethylene from ethane with an unprecedented selectivity of ~100, owing to its distinctive pore topology with large heart-shaped cages and framework flexibility. Control of such properties extends the boundaries for applicability of zeolites to challenging separations.

Organic structure-directing agents (OSDAs) are used to guide the formation of particular types of pores and channels during the synthesis of zeolites. We report that the use of highly versatile OSDAs based on phosphazenes has been successfully introduced for the synthesis of zeolites. This approach has made possible the synthesis of the elusive boggsite zeolite, which is formed by 10- and 12-ring intersecting channels. This topology and these pore dimensions present interesting opportunities for catalysis in reactions of industrial relevance.

It has been found that it is possible to obtain either polymorph B or the C of zeolite Beta with the same structure directing agent, i.e., 4,4-dimethyl-4-azoniatricyclo[5.2.2.0 2,6 ]undec-8-ene hydroxide. The synthesis occurs through a consecutive process in where polymorph B is firstly formed and then transformed into polymorph C. It is possible to produce a zeolite highly enriched in polymorph B, provided that the transformation of this phase into polymorph C is slowed down up to the point that BEC is only detected at trace levels. The structure of polymorph B has been determined by the first time by SAED and HRTEM from the areas of unfaulted polymorph B crystals.

By combining a rational design of structure directing agents and high throughput and data mining techniques, it has been possible to obtain Ge-free ITQ-24 as pure silica as well as borosilicate polymorphs up to a Si/TIII ratio of 10. Al can be exchanged by B giving strong acid materials. Also, the availability of the pure silica material allows one to determine more precisely the crystal symmetry. This work opens the possibility to synthesize the Ge-free polymorphs of a large number of new germanosilicate structures reported in the last five years. This certainly will increase their possibilities for industrial application.

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Previously elusive, the all‐silica pure polymorph C of zeolite beta and a material enriched with polymorph B (see picture) are prepared by high‐throughput (HT) synthesis in the presence of a cationic organic structure‐directing agent (SDA). The presence of K+ ions is essential for the formation of these materials; furthermore, a high ratio of OH− ions to silicon atoms favors the crystallization of polymorph C.

Molecular mechanics techniques and the use of atomic force fields have been used to calculate the energy of the system zeolite + structure directing agent (SDA), as well as the different energetic terms with their respective weights in deciding the final zeolite synthesis product. A new SDA has been found that discriminates energetically between two closely related zeolitic structures, ISV and BEC, that strongly compete during the crystallization process. The subsequent synthesis experiments with this new SDA led to the selective formation of ISV, thus supporting the predictions made by the computational chemistry calculations.