Search results for "Aluminosilicate"
showing 7 items of 47 documents
Chemical effect on the XPS spectra of the valence band and on O KLL and Pd MNN Auger spectra in pumice-supported catalysts
1992
X-ray photoelectron spectra of the valence band and X-ray-excited O KLL Auger transition of pumice-supported Pd and Pt catalysts have been obtained and compared to the corresponding spectra of pumice (a naturally occurring amorphous aluminosilicate). The changes observed indicate interaction between metal and support. The valence region of the catalysts consists of three large peaks: one due to the d band of the metals and the other to the O 2p non-bonding orbitals and bonding-type orbitals formed by a mixing of the atomic orbitals (O 2p, Si 3s and Si 3p) of oxygen and silicon from the support. The intensity decrease of the component due to the bonding orbitals, observed in the catalyst spe…
Theoretical study of oligomeric alumatranes present in the chemistry of materials from micro to mesoporous molecular sieves and alumina composites
2008
Quantum chemical calculations using density functional theory have been carried out to investigate molecular precursors based on alumatranes which are one of the components with silatranes for the preparation of mesoporous aluminosilicate materials. In the same way, some oligomeric alumatranes of this study take part in chemical syntheses related to materials such as zeolites and alumina composite. Gas phase and solution equilibrium geometries of the alumatrane precursors were fully optimized at B3LYP level, modeling solvent effects using a self-consistent reaction field (SCRF). From these optimized geometries, calculations of the 1 H, 13 C and 27 Al NMR chemical shifts at GIAO/B3LYP/6-31G(…
Influence of Sodium on the Structure and HDS Activity of Co–Mo Catalysts Supported ON Silica and Aluminosilicate
2000
Abstract Structural changes and catalytic performances of hydrodesulfurization (HDS) Co–Mo catalysts, supported on amorphous aluminosilicate (ASA) and amorphous SiO 2 were investigated as a function of the amount of sodium ions added to the supports. The catalysts were prepared according to the incipient wet impregnation method using (NH 4 ) 6 Mo 7 O 24 as molybdenum precursor and CoCl 2 or Co(NO 3 ) 2 as cobalt precursor. Structural and morphological characterisations of the materials were performed with X-ray diffraction (XRD) and surface area measurements (BET). In the case of the ASA-supported catalysts, increasing the amount of sodium resulted in a gradual decrease of the catalyst surf…
Single particle jumps and correlated ionic motions in glass-ceramics
1993
Using impedance spectroscopy, the ion transport in poorly Li-conducting aluminosilicate glass ceramics and their precursor glasses has been measured for temperatures 50 K < T < 550 K and covering a frequency range of more than 14 decades from 10 mHz up to 3 THz. In addition to the familiar cooperative ionic motion dominating at high temperatures, for the first time dielectric relaxation due to elementary hopping processes is observed well below room temperature.
Halloysite nanotubes as polyolefin fillers
2015
Artykuł stanowi przegląd najnowszej literatury dotyczącej nanokompozytów poliolefinowych napełnianych nanorurkami haloizytowymi (HNT). Omówiono wpływ dodatku HNT na osnowę poliolefinową, ze szczególnym uwzględnieniem morfologii oraz właściwości mechanicznych nanokompozytów poliolefina/HNT. Modyfikowane HNT wykazywały wysoki stopień rozproszenia w osnowie poliolefinowej, dzięki czemu powodowały poprawę właściwości mechanicznych poliolefinowych nanokompozytów napełnianych nanorurkami haloizytowymi. Połączenie korzystnych właściwości poliolefin, ekonomicznych metod ich przetwórstwa oraz unikatowych w³aoeciwooeci HNT pozwoli na szersze rozpowszechnienie nanokompozytów wytworzonych z ich udziałe…
Near‐IR Radiation‐Induced Attenuation of Aluminosilicate Optical Fibers
2021
The X-ray radiation-induced attenuation (RIA) growth kinetics are studied online in different single-mode aluminosilicate optical fibers in the near-IR (NIR) domain to evaluate their potential in terms of dosimetry. The optical fibers differ by Al contents, core sizes, drawing parameters, and also by a preform deposition process. The data show no dependence of the RIA on all these parameters, a positive result for the design of point or distributed radiation detectors exploiting RIA to monitor the dose. The RIA growth rate is unchanged for dose rates changing from 0.073 to 6.25 Gy(SiO2) s−1, and the RIA linearly increases with the dose up to 2 kGy(SiO2). Small but noticeable RIA changes are…
Sorption and mechanism studies of Cu2+, Sr2+ and Pb2+ ions on mesoporous aluminosilicates/zeolite composite sorbents
2020
The research aimed to develop a novel mesoporous aluminosilicate/zeolite composite by the template co-precipitation method. The effect of aluminosilicate (AlSi) and zeolite (NaY) on the basic properties and adsorption capacity of the resultant composite was conducted at different mass ratios of AlSi/NaY (i.e., 5/90, 10/80, 15/85, 20/80, and 50/50). The adsorption characteristics of such composite and its feedstock materials (i.e., aluminosilicates and zeolite) towards radioactive Sr2+ ions and toxic metals (Cu2+ and Pb2+ ions) in aqueous solutions was investigated. Results indicated that BET surface area (SBET), total pore volume (VTotal), and mesopore volume (VMeso) of prepared materials f…