Search

Mesoporous silica-based molecular sieves partially replaced with titanium are manufactured by templating. Titanium silicate materials exhibit catalytic activity toward oxidation of phenolic compounds and the transformation of benzene to phenol. The titanium silicate is a perfect molecular sieve catalyst in oxidizing alkanes and phenols.

X-ray diffraction, TGA-DTA, and (super 7)Li and (super 23)Na NMR data is presented for PEO nanocomposites made with natural and synthetic montmorillonite clays that provide new insight into interlayer structure. (super 23)Na NMR shows that PEO intercalculation results in the conversation of the multiple Na(super +) hydration states observed for the prostine clay into inner sphere sites most likely formed through coordination with the basal oxygens of the clay.

The mercury-binding mechanism for representative thiol-functionalized mesostructures by atomic pair distribution function analysis of synchroton X-ray powder diffraction data and by Raman spectroscopy is investigated. The Raman results indicate that the complexation of mercury centers by thiolate depends on the mercury loading.

The density functional theory (DFT) method is used to investigate the structure and bonding of silica and aluminosilicate nanoclusters containing five- and six-membered oxygen rings. The results reveal that an excitation energy at least 18 times larger than the room-temperature thermal energy is needed to break the stable five-membered ring structure, implying a high hydrothermal stability and acidity for this aluminosilicate structure.

The structure determination and an extensive exploration of the opportunities in the pore structure tailoring for a prominent member of ordered silicas with cage-like mesoporous structure (OSCMS) family are reported. It is shown that the temperature and time control during the synthesis allows one to gradually change cage-like pores of FDU-1 to a highly open and accessible porous system with narrow pore size distribution.

Two-dimensional, hexagonally ordered silicas with large uniform mesopores are assembled through a nonionic supramolecular assembly pathway using sodium silicate as a silica source and the triblock copolymer pluronic as a structure-directing agent. The materials exhibited adsorption properties highly similar to silica assembled through an electrostatic pathway under strongly acidic conditions, indicating the framework structure of analogues and consist of ordered large pores connected by micropores in the pore walls.

Thiol moieties which were grafted to the pore channel walls of mesoporous silica molecular sieves produced very effective heavy metal ion adsorbents which poses opportunities for operators of waste treatment and cleanup campaigns. Heavy metals such as lead and mercury are known to pollute the environment significantly to the detriment of natural ecosystems and human communities. Framework mesostructures that have many surface hydroxyl groups and huge pore channel parameters help develop framework channels which maintain appreciable open-framework features and various functional locations.

The replacement of amorphous aluminosilicated by derivatives of zeolite Y in gas oil cracking catalysts 40 years ago resulted in better product distribution, less coke formation, better stability, and lower catalyst consumption rates. Nanosized MSU-AS compositions possess the unique combination of mesoporosity, hydrothermal stability, acidity, and longevity that is desired for the efficient cracking of high molecular weight hydrocarbons.

A general route to mesostructured alumina containing transition alumina phase is reported. The study shows that surface areas are compatible with the values expected for a mesostructure with thick walls.

Aluminosilicate mesostructures that are steam stable were assembled from zeolite type Y seeds.