1344-28-1Relevant articles and documents
Synthesis of thermally stable χ-alumina by thermal decomposition of aluminum isopropoxide in toluene
Mekasuwandumrong, Okorn,Kominami, Hiroshi,Praserthdam, Piyasan,Inoue, Masashi
, p. 1543 - 1549 (2004)
Thermal decomposition of aluminum isopropoxide in toluene at 315°C resulted in χ-alumina that had high thermal stability, whereas the reaction at lower temperatures resulted in formation of an amorphous product. The χ-alumina thus obtained directly transf
Effect of milling on the formation of nanocrystalline x-Al 2O3 from gibbsite
Chaitree, Wasu,Jiemsirilers, Sirithan,Mekasuwandumrong, Okorn,Praserthdam, Piyasan,Charinpanitkul, Tawatchai,Panpranotw, Joongjai
, p. 3377 - 3383 (2010)
Gibbsite (FG) with mean particle diameter (d50 = 3μm) was milled in an attrition mill for 12 and 24 h using alumina balls as grinding media and calcined at different temperatures in the range of 350°-600°C. The properties of the alumina obtained were determined by X-ray diffraction, N2 physisorption, thermogravimetric/ differential thermal analyses, and transmission electron microscopy.Without milling, the alumina obtained normally contained the mixed phases between γ- and x-phase alumina. On the other hand, high purity of nanocrystalline vphase alumina (100 wt%) can be produced by calcination of the 24-h milled FG at 600°C. The isothermal kinetics measurements revealed that the rate constant (κ) for phase transformation increased as the particle size of gibbsite decreased and the calculated activation energy for transformation from FG to alumina decreased from 20.6 to 14.7 and 6.8 kJ/mol after milling for 12 and 24 h, respectively. The physical properties of nanocrystalline x-alumina obtained by the calcination of milled FG were comparable to those produced by the solvothermal method. The present results offer a simple way to prepare a large amount of pure x-phase alumina for particular industrial applications.
Studies on the thermal reactions of aluminium oxides and hydroxides
Novak, C.,Pokol, G.,Tomor, K.,Koemives, J.,Gal, S.
, p. 765 - 770 (1988)
The gibbsite →χ-alumina decomposition (in air) and the χ-alumina →boehmite transformation (under hydrothermal conditions) were investigated isothermally. Reaction products were characterized by TG and X-ray diffraction. The rate of the gibbsite →χ-alumina
Preparation and microstructural and textural characterization of single-phase aluminum oxides
Kul'ko,Ivanova,Litvak,Kryukova,Tsybulya
, p. 714 - 721 (2004)
Conditions for the preparation of single-phase η-, -, and χ-aluminas were determined. The structures of η- and χ-aluminas were characterized. With the use of high-resolution electron microscopy, it was found that η-Al2O3 particles exhibited the most developed {111} face and consisted of coherently joined domains with a pronounced platelet shape. Planar defects in the (111) plane occurred in the η-Al2O3 particles. Microstructural differences between single-phase η-Al2O3 and γ-Al2O 3 with a defect spinel structure were revealed. It was found that the η-Al2O3, χ-Al2O3, and -Al2O3 oxides are characterized by uniformly porous structures with average pore diameters of 47, 55, and 110 A, respectively.
Formation of the morphology of continuous-precipitation aluminum hydroxides in the course of industrial synthesis
Lamberov,Aptikasheva,Egorova,Levin,Gil'manov
, p. 171 - 177 (2005)
X-ray phase and differential thermal analyses were used to study in detail how the morphology of aluminum hydroxides changes in separate stages of the technological process. The assumption that two pseudoboehmite modifications differing in crystallite dim
Hauthal, T.,Pap, I. S.,Mink, G.,Blumenthal, G.,Szekely, T.
, p. 79 - 90 (1990)
Optical, electrical and dielectric properties of mixed metal oxides derived from Mg-Al Layered Double Hydroxides based solid solution series
Lahkale,Sadik,Elhatimi,Bouragba,Assekouri,Chouni,Rhalmi,Sabbar
, (2021/11/04)
In this work, we investigated the effect of aluminum content on optical, electrical and dielectric properties of mixed metal oxides (MMOs), obtained from calcination at 726 K of solid solution series based on nitrate intercalated Mg1-xAlx Layered Double Hydroxides (x = 0.167, 0.20, 0.25, 0.33). Subsequently, the MMOs were characterized by X-Ray Diffraction, and analyzed by Inductively Coupled Plasma, Scanning Electron Microscopy, Diffuse Reflectance Spectroscopy and Impedance Spectroscopy. It was found a shift of light absorption towards shorter wavelengths, and an increase of conductivity and dielectric constant when the aluminum content increased. Higher aluminum content exhibited strong ultraviolet light absorption with average band gap of 6.29 eV, and also manifested high reflectance in visible and near-infrared wavelengths, whereas lower aluminum content showed lower values of conductivity, dielectric constant and dielectric loss tangent. Moreover, the electrical, dielectric and optical parameters of MMOs were reported and discussed.
Electroluminescent polycrystalline Er-doped Lu3Al5O12 nanofilms fabricated by atomic layer deposition on silicon
Ma, Zhiqiang,Sun, Jiaming,Xu, Jing,Yang, Li,Yang, Yang
, (2021/07/06)
The sub-nanometer composition and interlayer thicknesses of the silicon-based Lu2O3/Al2O3 nanolaminates are regulated by atomic layer deposition, to fabricate polycrystalline Er-doped Lu3Al5/sub
Interesterification of triglycerides with methyl acetate for the co-production biodiesel and triacetin using hydrotalcite as a heterogenous base catalyst
Dhawan, Manali S.,Barton, Scott Calabrese,Yadav, Ganapati D.
, p. 101 - 111 (2020/08/21)
Biodiesel is a renewable fuel with several advantages over petro-based fuels and is conventionally produced by the transesterification of triglycerides with alcohols. Chemical interesterification of triglycerides is a good alternative as compared to transesterification, as it yields a value-added compound, triacetin, as a co-product instead of the already abundant commodity, glycerol. In this work, interesterification of soybean oil was carried out with methyl acetate to co-produce biodiesel and triacetin, using calcined hydrotalcite as a heterogeneous base catalyst. Several base catalysts were tested for this reaction. Calcined Mg-Al hydrotalcite (Mg:Al mole ratio – 3:1) was found as the best catalyst for achieving 95.9 % conversion of soybean oil triglycerides in 4 h and yielding 5.3 % selectivity of triacetin along with the value-added intermediates - monoacetindiglycerides and diacetinmonoglycerides, produced with a selectivity of 46 % and 48.7 %, respectively. The optimum reaction conditions were found at an oil to methyl acetate mole ratio of 1:50, catalyst loading of 0.04 g/cm3 and a temperature of 200 oC. The catalysts were fully characterized before and after the reaction, and were found to possess high surface area with both basic and acidic sites. The effect of various reaction conditions on the rate of reaction, conversion of triglycerides and selectivity of triacetin were studied. The concentration profiles of the reactants, intermediates and products obtained at different temperatures were used to obtain the kinetic rate constants and the activation energy of each parallel step was evaluated. Reusability studies showed that the catalyst was stable and reusable up to three cycles.