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mesoporous silica in synthetic saponite clays . Chem Mater 12 , 2698 ( 2000 ) 4. Han Y-S , Matsumoto H , Yamanaka S : Preparation of new silica
SBA-15 silicas containing sucrose
Chemical, structural, and thermal studies
Introduction During the last 20 years, a significant progress has been achieved in the field of ordered mesoporous silicas (OMSs) [ 1 – 3 ]. OMSs constitute an exciting field in materials chemistry due to many potential
Thermal transformation of polyacrylonitrile deposited on SBA-15 type silica
Effect on adsorption capacity of methyl–ethyl ketone vapor
adsorption properties. In the present study we have demonstrated highly effective adsorbents of VOCs obtained by thermal decomposition of PAN deposited on SBA-15 type mesoporous silica developing the available surface of carbonaceous species. This
Introduction Nanostructured materials have attracted substantial interest in many fields of science because of their potential application [ 1 ]. Among them the ordered mesoporous silicas, such as MCM-41 or SBA-15, exhibiting
transition metals into the framework of such materials (especially titanium) gives additional special catalytic properties [ 3 – 11 ]. Silica-titania materials (STM) possessing different compositions and physico-chemical characteristics are widely
. This necessitated the utilization of micro filler silica fume (SF) as a supplementary cementitious material that fills up the voids in the concrete thereby enhancing its performance [ 2 ]. Various researches on the utilization of SF have shown improved
Abstract
The article presents the results of testing thermal properties and combustibility of butadieneacrylonitrile rubber with 18% contents of bounded acrylonitrile, NBR 18. Two types of silica, Zeosil 175C and Ultrasil VN-3, with different specific surfaces were used as filler. Zeosil 175C and Ultrasil VN-3 were modified via cryogenic dezaggregation method. The activity of unmodified and cryogenic modified silica toward butadiene-acrylonitrile rubber were investigated. The sulphur and peroxide vulcanizates contained 20, 30, 40, and 50 phr. of the filler were studied. The article discusses also the test results of thermal stability and flammability of NBR 18 containing silica prepared "in situ" from alkoxysilane precursor. The test results were obtained with the use of derivatograph, measurements of flammability by the method of oxygen index, and in air. The effect of the silica modification on the SEM and AFM was also examined. The method of cryogenic modification enables to achieve increase of mineral fillers activity towards elastomer and reduction in the flammability of NBR 18 vulcanizates. It has been found that the modification of the vulcanizates of NBR 18 with tetraethoxysilane that makes it possible to form silica "in situ" reduces the flammability of cross-linked rubbers.
Abstract
The chiral vanadyl salen complex was immobilized into mesoporous silica by a covalent grafting method using 3-aminopropyltriethoxysilane as a reactive surface modifier. The formation and integrity of the complex have been confirmed by FT-IR, UV–vis and BET measurements and the complex was tested in the asymmetric oxidation of sulfide to sulfoxide using H2O2 as oxidant. The immobilized complex showed better catalytic activity than the neat complex, while the neat complex has deactivated in the reaction. The combination of the heterogenized catalyst, H2O2 and CH2Cl2 as solvent offers a selective catalytic system for oxidation of sulfide to sulfoxide with a low but significant enantioselectivity in the range of 8–10% ee. In addition, the heterogenized catalyst could be easily separated from the products and reused.
The Terebratel Beds of the Karlstadt section are composed of bioclastic grainstone revealing distinct layers of ooidal grainstone (Fig. 4 ). In thin sections, these layers show silicification of ooids and interparticle silica cement (Fig. 5a – c
