Novel Strategy for the Synthesis of Ultra-Stable Single-Site Mo-ZSM-5 Zeolite Nanocrystals.

The current energy transition presents many technological challenges, such as the development of highly stable catalysts. Herein, we report a novel "top-down" synthesis approach for preparation of a single-site Mo-containing nanosized ZSM-5 zeolite which has atomically dispersed framework-molybdenum homogenously distributed through the zeolite crystals. The introduction of Mo heals most of the native point defects in the zeolite structure resulting in an extremely stable material.

Direct Evidence for Single Molybdenum Atoms Incorporated in the Framework of MFI Zeolite Nanocrystals.

Direct evidence of the successful incorporation of atomically dispersed molybdenum (Mo) atoms into the framework of nanosized MFI zeolite is demonstrated for the first time. Homogeneous distribution of Mo with a size of 0.05 nm is observed by scanning transmission electron microscopy high-angle annular dark-field imaging (STEM-HAADF).

Specific Surface Area Determination for Microporous/Mesoporous Materials: The Case of Mesoporous FAU-Y Zeolites.

A methodology for determining the micropore, mesopore, and external surface areas of hierarchical microporous/mesoporous materials from N adsorption isotherms at 77 K is described. For FAU-Y zeolites, the microporous surface area calculated using the Rouquerol criterion and the Brunauer-Emmett-Teller (BET) equation is in accord with the geometrical surface determined by the chord length distribution method. Therefore, BET surface area ( S) is the well representative of micropore surface areas of microporous materials and of total surface area of microporous/mesoporous materials.

Revelation on the Complex Nature of Mesoporous Hierarchical FAU-Y Zeolites.

The texture of mesoporous FAU-Y (FAUmes) prepared by surfactant-templating in basic media is a subject of debate. It is proposed that mesoporous FAU-Y consists of: (1) ordered mesoporous zeolite networks formed by a surfactant-assisted zeolite rearrangement process involving local dissolution and reconstruction of the crystalline framework, and (2) ordered mesoporous amorphous phases as Al-MCM-41, which coexist with zeolite nanodomains obtained by a dissolution-reassembly process. By the present systematic study, performed with FAU-Y (Si/Al = 15) in the presence of octadecyltrimethylammonium bromide and 0 < NaOH/Si ratio < 0.

Ultimate size control of encapsulated gold nanoparticles.

We report an original and scalable synthesis pathway to produce encapsulated gold nanoparticles. Precise control of the gold particles is achieved in the range of 1-10 nm through the impregnation of silicalite-1 with a controlled concentration of gold solution, followed by dissolution-recrystallization of the zeolite.

One-pot preparation and CO2 adsorption modeling of porous carbon, metal oxide, and hybrid beads.

Hierarchically porous carbon (C), metal oxide (ZrTi), or carbon-metal oxide (CZrTi) hybrid beads are synthesized in one pot through the in situ self-assembly of Pluronic F127, titanium and zirconium propoxides, and polyacrylonitrile (PAN). Upon contact with water, a precipitation of PAN from the liquid phase occurs concurrently with polymerization and phase separation of the inorganic precursors. The C, ZrTi, and CZrTi materials have similar morphologies but different surface chemistries.