Al site distribution in the structurally complex and industrially important ZSM-5 zeolite is determined by studying the spectroscopic response of Al(OSi) units and using a self-consistent combination of up-to-date solid-state NMR correlations (Si-Al and H-Al D-HMQC) and quantum chemistry methods (DFT-D). To unravel the driving forces behind specific Al sitting positions, our approach focuses on ZSM-5 containing its more efficient OSDA, tetrapropylammonium.

The main approaches for engineering and healing of defects in zeolites known for their iconic shape-selective properties widely explored in key areas such as catalysis, waste management, gas separation and biomedicine are revealed.

The synthesis of nanostructured zeolites enables modification of catalytically relevant properties such as effective surface area and diffusion path length. Nanostructured zeolites may be synthesized either in alkaline media, and so contain significant numbers of hydrophilic silanol groups, or in expensive and harmful fluoride-containing media. Here, we report and characterize, using a combination of experimental and theoretical techniques, the one-pot synthesis of silanol-free nanosized MFI-type zeolites by introducing atomically dispersed tungsten; this prevents silanol group occurrence by forming flexible W-O-Si bridges. These W-O-Si bonds are more stable than Si-O-Si in the all-silica MFI zeolite. Tungsten incorporation in nanosized MFI crystals also modifies other properties such as structural features, hydrophobicity and Lewis acidity. The effect of these is illustrated on the catalytic epoxidation of styrene and separation of CO and NO. Silanol-free nanosized W-MFI zeolites open new perspectives for catalytic and separation applications.

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The amount and location of acid sites (strong Brønsted and weak silanols) in zeolites are crucial for their applications. In this work we revealed the enigma of the complex H-bonded...

The engineering of RHO nanozeolite is demonstrated by synthesis from a colloidal precursor suspension using only inorganic structure-directing agents (Na + , Cs + ), whereby the particle morphology, Si/Al ratio, cation content, stability, and flexibility are tailored. RHO nanozeolite with a higher Si/Al ratio (2.0) and superior thermal stability (up to 700 °C) compared to previous reports is synthesized. Optimization of the synthesis procedure by introducing additional Si precursors facilitated the targeted improvement in the Si/Al ratio while maintaining the nanosized dimensions of the discrete zeolite crystals with well-defined rhombic dodecahedral morphology. The structural properties of the RHO nanozeolites are characterized by in situ variable-temperature X-ray powder diffraction (XRPD) experiments showing that the nanozeolites possess a single structural phase up to 740 °C; further heating to 760 °C induces a symmetry change from noncentrosymmetric to centrosymmetric associated with a large increase in the anisotropic displacement parameter of the Cs + extra-framework cations. The structural behavior is unique compared to more siliceous Na + and Cs + -containing RHO zeolites (Si/Al ≥ 3), which possess a centrosymmetric structure when hydrated. These experiments reveal a delineation, based on the Si/Al ratio and content of the extra-framework cations between the as-synthesized Na + and Cs + -containing RHO zeolites that possess centrosymmetric or noncentrosymmetric symmetry when hydrated, as well as single or coexisting structural phases, expanding the scope of intelligently designed nanozeolites with tailored properties for precise applications.

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