Ordered mesoporous materials in catalysis

Ordered mesoporous materials

The area of periodic mesoporous materials prepared by cooperative assembly in the presence of amphiphile molecules underwent dramatic growth. Among the silica-based materials, many types may be reg...

Periodic Mesoporous Silica-Based Organic−Inorganic Nanocomposite Materials

http://kidneys.zaslavsky.com.ua/article/download/84325/116293

Європейське керівництво з профілактики серцево-судинних захворювань у клінічній практиці — 2016

Mobility, bioavailability and pH-dependent leaching of cadmium, zinc and lead in a contaminated soil amended with biochar.

The location and coordination of titanium in the titanosilicate mesoporous molecular sieve MCM-41 prepared from Ti(IV) ethoxide as the source of titanium was studied by XRD, IR spectroscopy, 29Si MAS NMR, and XANES. The results are interpreted on the basis of isomorphous substitution of Ti for Si. XANES shows that titanium is 4-coordinate and that Ti(IV) does not form a regular TiO4 tetrahedron. This is caused by the larger size of the Ti(IV) atom in comparison with Si(IV), resulting in a distortion in the silica matrix, and/or by the presence of H2O in the coordination sphere of titanium. Such distortion is consistent with the line broadening observed in the 29Si MAS NMR spectra, brought about by the wider distribution of the Si−O−Si angles in SiO4 tetrahedra as titanium is progressively incorporated in the silica matrix, and with the changes in the vibrational lattice infrared bands.

Titanosilicate Mesoporous Molecular Sieve MCM-41: Synthesis and Characterization

We have used powder X-ray diffraction, diffuse reflectance Fourier-transform infrared, 29Si MAS NMR, N2 adsorption, and transmission electron microscopy to examine the role of the concentration of silica, the surfactant, and the reaction time in the synthesis of high-quality silica mesoporous molecular sieve MCM-48. The XRD patterns of the products are consistent with the hexagonal → cubic → lamellar phase transformation.

Synthesis and Characterization of the Mesoporous Silicate Molecular Sieve MCM-48

The acidity and catalytic properties of aluminosilicate mesoporous molecular sieves with the MCM-41 structure and bulk Si/Al ratios in the 10–60 range have been investigated. The incorporation of 4-coordinate aluminium into the structure of MCM-41 generates both BrOnsted and Lewis acid sites in amounts increasing with the degree of incorporation. However, the BrOnsted/Lewis acid population ratio is independent of the content of aluminium. The number and strength of acid sites generated are comparable to those of a pillared acid-activated clay and lower than in zeolite H-Y with Si/Al=3.65. Aluminosilicate MCM-41 is a moderate catalyst for the conversion of cumene which proceeds predominantly via catalytic cracking to propene and benzene. The sample of MCM-41 with the highest content of framework aluminium (Si/Al=10) has the largest number of BrOnsted acid sites and exhibits highest catalytic activity.

Acidity and catalytic activity of the mesoporous aluminosilicate molecular sieve MCM-41

Toward a smart optical biosensor based on nanoporous anodic alumina (NAA): by modifying the pore geometry in nanoporous anodic alumina we are able to change the effective medium at will and tune the photoluminescence of NAA. The oscillations in the PL spectrum are converted into exclusive barcodes, which are useful for developing optical biomedical sensors in the UV-Visible region.

Nanoporous Anodic Alumina Barcodes: Toward Smart Optical Biosensors

This review provides a perspective on porous silicon (pSi)–based nanomaterials including nanoparticles, nanowires, and thin films, that are currently being used in advanced therapy, imaging, and sensing, with a focus on their effective use in future clinical settings. The achievement of both controlled geometry and architecture, and surface chemistry motifs, are presented as the two key parameters that dictate the nature of interactions with the biological entities. The authors discuss the role of the degradation kinetics in a biological environment into nontoxic by‐products. pSi is presented as increasingly fulfilling a central task in various biomedical applications and clinical settings, owing to its unique physiochemical properties.

María D. Alba

Papers

Titanosilicate Mesoporous Molecular Sieve MCM-41: Synthesis and Characterization

Synthesis and Characterization of the Mesoporous Silicate Molecular Sieve MCM-48

Acidity and catalytic activity of the mesoporous aluminosilicate molecular sieve MCM-41

Nanoporous Anodic Alumina Barcodes: Toward Smart Optical Biosensors

Advances in Porous Silicon–Based Nanomaterials for Diagnostic and Therapeutic Applications