Glycerol acetylation on mesoporous KIL-2 supported sulphated zirconia catalysts

Zirconia nanomaterials were prepared by impregnation of KIL-2 type silica with 4, 8 and 12 wt.% ZrO2 and were modified by sulphate groups in order to vary the type and strength of acidity. Samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and N2 physisorption methods. Acidic properties of adsorbed pyridine were investigated by FT-IR spectroscopy. The catalytic performance of ZrKIL-2 and SO4 2−/ZrKIL-2 in glycerol esterification with acetic acid was studied and compared to that of pure zirconia varieties. It was found that silica-supported zirconia samples are more active than pure zirconia ones. With increasing ZrO2 content, KIL-2-supported catalysts showed increasing catalytic activity and selectivity in producing valuable fuel additives, di- and triacetyl glycerols. Sulphated analogues showed even higher activity and selectivity compared to non-sulphated ones due to their strong Brönsted acidity

Structural and Morphological Transformations of the (NH4, Na)-exchanged Zeolites 4A, 13X and Synthetic Mordenite by Thermal Treatment

Thermal treatment of (NH4, Na)-exchanged zeolites 4A and 13X results in the formation of an amorphous phase (T < 1000 °C) and a crystalline phase of mullite at temperatures above 1000 °C. No structural changes have been noticed for the (NH4, Na)-exchanged synthetic mordenite treated under the same conditions. Scanning electron microscopy (SEM), X-ray powder diffraction, Fourier transform infrared (FT-IR) spectroscopy and particle size analysis were used to characterize the initial materials and the obtained products

Kinetic Analysis of Non-isothermal Transformation of Zeolite 4A into Low-carnegieite

Kinetics of the non-isothermal transformation of zeolite 4A to low-carnegieite was investigated by the X-ray diffraction method. Changes in the fractions of zeolite 4A, amorphous aluminosilicate and low-carnegieite during zeolite 4A heating at three different heating rates (0.0833 ° s–1, 0.1667 ° s–1 and 0.333 ° s–1) showed that amorphization of zeolite 4A and crystallization of low-carnegieite take place simultaneously. Kinetic analyses of amorphization and crystallization showed that the non-isothermal transformation took place by the same mechanism as the isothermal transformation, i.e., amorphization of zeolite 4A proceeded by a random, diffusion- limited agglomeration of the short-range ordered aluminosilicate subunits formed by the thermally induced breaking of Si-O-Si and Si-O-Al bonds between different building units of zeolite framework. Crystallization of low-carnegieite occurred by homogeneous nucleation of low-carnegieite inside the matrix of amorphous aluminosilicate and was diffusion-controlled, with one-dimensional growth of the nuclei. Kinetics of non-isothermal processes was determined by the changes of the rate constants during heating and the apparent activation energies of amorphization and crystallization

New two-component water sorbent CaCl2FeKIL2 for solar thermal energy storage

) and similar mesopore dimensions as the matrix. The maximum water sorption capacity of FeKIL2 is 0.21 g/g, while the composite possesses 3 times higher maximum water sorption capacity due to the presence of the salt in the matrix. Heat of adsorption of the composite is 50.4 kJ/mol. A short-term cycling test between temperatures of 150 and 40°C at a water vapour pressure of 5.6 kPa confirms a comparatively good hydrothermal stability of the composite

Synthesis of biomass derived levulinate esters on novel sulfated Zr/KIL-2 composite catalysts

Zirconia nanomaterials were prepared by impregnation of KIL-2 type silica with 4, 8, 15 and 25 wt% of ZrO2, and were modified by sulfate groups in order to vary the type, strength and density of the active sites. The samples were characterized by X-ray powder diffraction (XRD), EDX analysis, N-2 physisorption, SEM, TEM, UV Vis spectroscopy, XPS, and thermogravimetric analysis (TGA). The acidic properties were investigated by FT-IR spectroscopy of adsorbed pyridine. The catalytic properties of ZrKIL-2 catalysts and their sulfated varieties were studied in levulinic acid (LA) esterification with ethanol or n-butanol. The sulfated materials showed significantly higher activity compared to the non-sulfated ones due to their stronger Bronsted and Lewis acid sites. It was found that the silica supported sulfated samples show different activity depending on the applied alcohol. With increasing ZrO2 content up to 15 wt% increasing catalytic activity and selectivity was observed to produce levulinate esters. A further increase of the amount of zirconia leads to a decrease in catalytic activity because of the significant decrease of ZrO2 dispersion and the structure deterioration of the catalyst. For the first time insight was provided into the relation between sulfates group leaching and zirconia dispersion. (C) 2016 Elsevier Inc. All rights reserved

Association of circadian rhythm genes ARNTL/BMAL1 and CLOCK with multiple sclerosis

Prevalence of multiple sclerosis varies with geographic latitude. We hypothesized that this fact might be partially associated with the influence of latitude on circadian rhythm and consequently that genetic variability of key circadian rhythm regulators, ARNTL and CLOCK genes, might contribute to the risk for multiple sclerosis. Our aim was to analyse selected polymorphisms of ARNTL and CLOCK, and their association with multiple sclerosis. A total of 900 Caucasian patients and 1024 healthy controls were compared for genetic signature at 8 SNPs, 4 for each of both genes. We found a statistically significant difference in genotype (ARNTL rs3789327, P = 7.5.10(-5); CLOCK rs6811520 P = 0.02) distributions in patients and controls. The ARNTL rs3789327 CC genotype was associated with higher risk for multiple sclerosis at an OR of 1.67 (95% CI 1.35-2.07, P = 0.0001) and the CLOCK rs6811520 genotype CC at an OR of 1.40 (95% CI 1.13-1.73, P = 0.002). The results of this study suggest that genetic variability in the ARNTL and CLOCK genes might be associated with risk for multiple sclerosis