Investigation of characterizing methods for the microstructure of cement

Volumetric, gravimetric, calorimetric, flow methods, mercury porosimetry and laser granulometry were used to investigate the surface structure and the sorption behavior of industrial cements and hydrated cement paste. The suitability of the measuring methods is assessed.

Metal Oxide Containing Mesoporous Silica with Bicontinuous “Plumber's Nightmare” Morphology from a Block Copolymer-Hybrid Mesophase

Pore structural characteristics of mesostructured materials prepared under different conditions

This paper presents an overview of the pore structural properties of different mesostructured materials prepared at room temperature, namely MCM-41, MCM-48 and MMS. The stability towards water vapour of some samples is inferred by XRD and nitrogen adsorption after and prior to water adsorption. It is shown that MMS materials are more stable than MCM-41. A new method for the stabilisation of MCM-41 using tetraethoxysilane (TEOS) in hexane as silicification agent is proposed and it is shown to be effective in stabilising the pore structure and to increase significantly the surface hydrophobicity.

ChemInform Abstract: The Synthesis of Spherical Mesoporous Molecular Sieves MCM-48 with Heteroatoms Incorporated into the Silica Framework.

Synthesis of spherical porous silicas in the micron and submicron size range: challenges and opportunities for miniaturized high-resolution chromatographic and electrokinetic separations.

Classical silica technology has reached its limit with respect to an ultimate minimum particle size of about 2 microm in diameter. Here, a novel process is presented which allows one to synthesize porous silica beads and control their particle diameter in situ, within the range of 0.2-2.0 microm. As a result, no sizing is required and losses of silica are avoided. Furthermore, the process enables one to control in situ the pore structural parameters and the surface chemistry of the silica beads. Even though surface funtionalized silicas made according to this process can principally be applied in fast HPLC the column pressure drop will be high even for short columns. In addition, the column…

Novel synthesis of spherical MCM-48

Abstract A novel synthesis route was developed for the cubic member of the M41S family, MCM-48, with a three-dimensional pore system allowing the formation of submicrometre- to micrometre-sized beads with a narrow pore-size distribution. The synthesis is based on the modified Stober method applying tetraethoxysilane, ethanol, water, ammonia and n -hexadecyltrimethylammonium bromide as template. The specific surface area, the specific pore volume and the average pore diameter were varied in the following ranges: 900–1600 m 2  g −1 , 0.5–0.9 cm 3  g −1 and 2–3 nm. Aluminium-, chromium-, gallium-, niobium- and vanadium-MCM-48 were also synthesized following this procedure.

MCM-41, MCM-48 and related mesoporous adsorbents: their synthesis and characterisation

MCM-41, MCM-48, MCM-41 analogue materials and disordered silica xerogels were compared with respect to their long range and short range order, their specific surface area, pore structure and pore structural parameters, pore wall thickness and their surface hydroxyl group concentration. Based on X-ray diffraction data it could be seen that the degree of long range order decreased in the order MCM-41>MCM-48>MCM-41 analogues >amorphous silica xerogels. The particle porosity and pore wall thickness increased in the same sequence such that MCM-41 analogues and amorphous silica xerogels were more stable towards water and water vapour. The concentration of the surface hydroxyl groups increased whe…

Rational design, tailored synthesis and characterisation of ordered mesoporous silicas in the micron and submicron size range

Characterization of MCM-48 Materials

Mesoporous molecular sieves of MCM-48 type were prepared by conventional hydrothermal and novel room temperature syntheses. Scanning electron microscopy (SEM) studies have shown that nonagglomerate...

The Synthesis of Spherical Mesoporous Molecular Sieves MCM-48 with Heteroatoms Incorporated into the Silica Framework

A novel approach to polymer-template mesoporous molecular sieves

A novel synthesis route was developed to produce spherical silica particles. The synthesis is based on a modified Stoeber method and the room-temperature synthesis of MCM 41S-materials applying tetraethoxysilane, alcohol, water, ammonia and homopolymers as template. The specific surface area, the specific pore volume and the average pore diameter were varied in the following ranges: 5 – 1,000 m2/g; 0.1 – 1.0 cm3/g and 2-50 nm. With respect to catalytic applications hetero-atoms e.g. Al were incorporated into the silica framework.