Highly hydrothermal stable mesoporous molecular sieves (TZM) prepared by the self assembly of zeolitic subunits from ZSM-5 desilication and their catalytic performance for CO2 reforming of CH4

We demonstrated a new strategy for the preparation of highly stable mesoporous molecular sieves (TZM) by the desilication of ZSM-5 zeolite and self-assembly of the zeolite subunits in a Na₂O·(3.3–3.4) SiO₂ aqueous solution.

Novel protonated Fe-containing mesoporous silica nanoparticle catalyst: excellent performance cyclohexane oxidation

H/Fe-MSN exhibited high activity for the oxidation of cyclohexane to cyclohexanone in the presence of hydrogen peroxide at 298 K for about 1 h, giving a 97% yield.

Investigation of Y/SBA Composite Molecular Sieves Morphology Control and Catalytic Performance for n-Pentane Aromatization

Using Y molecular sieve as the core, Y/SBA-15 composite molecular sieves were prepared by different crystallization methods in the paper. The growth process and morphologies of the composite molecular sieves were controlled by adjusting the synthesis factors. The structures and acidity of two kinds of composite molecular sieves were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), and NH3-TPD. The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane. The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization. The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves.

Mercaptosilane-assisted synthesis of sub-nanosized Pt particles within hierarchically porous ZSM-5/SBA-15 materials and their enhanced hydrogenation properties

A novel catalyst that consists of sub-nanosized Pt particles within hierarchically porous ZSM-5/SBA-15 materials was synthesized. This catalyst exhibited high stability and a hierarchically porous structure of a micro-mesoporous composite and possessed a high density of active sites by confinement of sub-nanosized Pt particles within small-pore zeolites, showing high catalytic properties for the hydrogenation of 1,3-butadiene and cyclooctadiene at room temperature.

Monodisperse Aluminosilicate Spheres with Tunable Al/Si Ratio and Hierarchical Macro-Meso-Microporous Structure

While tremendous success has been seen in the development of ordered mesoporous silica by soft-templated methods, synthesis of hierarchical structures with controllable multiscale pore networks has remained a challenging topic. On the other hand, introduction of heteroatoms as an effective method of chemically functionalizing silica leads to difficulties in morphological control of the product, and multistep synthesis has been necessary for functionalized silica particles with hierarchical pore structure and uniform size. The present work demonstrates that the conflict between morphological control and heteroatom incorporation can be resolved in a CTAB-stabilized toluene-water-ethanol microemulsion system. For the first time, monodisperse macro-meso-microporous aluminosilicate spheres (MASS) are synthesized in one step at room temperature. Simultaneous tuning of Al/Si ratio (0-0.35) and the hierarchical pore structure is realized by Hofmeister anion effects of the Al source itself, [Al(OH)4](-), which change the geometry of CTAB micelles and giant vesicles. The Al is incorporated purely in a tetrahedrally coordinated status, and preliminary results from catalytic experiments show improved acidity of MASS as a catalyst support.

Investigation on the effect of zeolite precursor on the formation process of MCM-41 containing zeolite Y building units

The formation process of MCM-41 containing zeolite Y building units has been investigated by UV Raman spectroscopy, (29)Si and (27)Al MAS NMR spectroscopy, X-ray diffraction (XRD), N2 adsorption and electron microscopy (SEM and TEM). It is found that the precursor containing zeolite Y secondary building units promotes the formation of a metastable mesopore structure just after mixing the zeolite precursors with CTAB. In contrast, the low-polymerized aluminosilicates and well-crystallized zeolite crystals cannot be assembled with CTAB at this stage. The result supports that the zeolite secondary building units should promote to the formation of the mesopore wall. This has been ascribed to its high anionic charge density as well as the appropriate multidentate coordination. Lowering down the pH value to 9.3 facilitates the further polymerization of the aluminosilicate species to build up a stable mesoporous phase.