Synthesis Of Mesoporous Γ-alumina Research Articles

Synthesis of mesoporous γ-alumina from a low-grade boehmite ore: Effect of thermal/chemical processing order on physico-chemical characteristics of adsorbent and regeneration of used transformer oils

Mesoporous γ-alumina adsorbents were synthesized from a low-grade boehmite ore, using the heat-treatment/acid-leaching (TC) and vice-versa (CT), under 400–600℃, 2–6 M HCl and H2SO4 solutions. The crystallinity of active species, morphology, elemental mapping, specific surface area, gravimetric phase changes, and chemical composition of the samples were characterized. The 0.50–1.00 mm γ-alumina prepared through heating, and followed by acid leaching with HCl (TC sample) presented mesoporous structure with the highest specific surface area of 245.802m2/g, pore volume 0.32773cm3/g, and average pore diameter of 44.3420A0. Using both CT and TC adsorbents, along with a commercial adsorbent, for the regeneration of used transformer oil, the TC adsorbent demonstrated the best performance, resulting in improved oil properties such as viscosity, interfacial tension, total acid number, dielectric dissipation factor, resistivity, and moisture content. Furthermore, the TC adsorbent was affected less by surface attrition and producing fine debris during recovery of oil compared to the commercial one.

The effect of polyoxyethylene (40) stearate surfactant on novel synthesis of mesoporous γ-alumina from Kano kaolin

Mesoporous γ-alumina was synthesized by acid extraction of alumina from Kano kaolin using polyoxyethylene (40) stearate (PS) as a surfactant. The synthesized alumina was characterized using X-ray diffraction (XRD), N2 adsorption–desorption, Fourier transform infra-red spectroscopy (FTIR), field emission scanning electron microscopy attached with energy-dispersive X-ray (FESEM–EDX), and thermogravimetric analysis (TG–DTA). High-purity mesoporous γ-Al2O3 with relatively large surface area and narrow pore size distribution was obtained. For comparison the preparation in the absence of surfactant was also carried out. In this study mesoporous alumina was also obtained even in the absence of the surfactant, however, the addition of PS resulted in modification on physical properties and morphology. The surface area increased from 169.0m2/g to 222.7m2/g, pore size from 4.4nm to 5.6nm and pore volume from 0.32cm3/g to 0.45cm3/g. Crystallite size was also found to increase from 2.68nm to 3.33nm after the addition of the surfactant.

Synthesis of mesoporous γ-alumina by sol–gel process and its characterization and application for sorption of Pu(IV)

Mesoporous γ-alumina samples were prepared by the sol–gel process from the boehmite sol having different template solutions. Copper doped material was also prepared from sol containing template solution along with copper nitrate. Studies were performed to understand the influence of templates on the morphology of the synthesized samples particularly with respect to specific surface area and porosity. Synthesized samples were used to study sorption of Pu(IV) from nitric acid–oxalic acid solutions. Distribution ratios (D) for Pu(IV) were determined using the γ-alumina samples with an objective to employ these for the recovery of Pu.

Synthesis of Mesoporous γ-alumina Assisted by Room Temperature Ionic Liquid

Boehmite Sols were used as aluminum precursors for preparing mesoporous alumina with crystalline framework walls in the presence of 1-butyl-3-methyl imidazolium tetrafluoroborate([BMIM][BF4]).The structure of the γ-Al2O3 was examined by N2 physical adsorption,X-ray powder diffraction(XRD),transmission electron microscope(TEM),and solid state 27Al MAS NMR spectra.The results show that alumina with the three-dimensional interconnected scaffold-like channels displays very rich porosities with large mesopores,and the addi-tion of [BMIM][BF4] could improve the pore properties of alumina significantly.

Synthesis of mesoporous γ-alumina through pre- and post-hydrolysis methods

Two methods of pre- and post-hydrolysis are suggested for the preparation of mesoporous aluminas. These techniques were developed based on the control of the reaction rates of hydrolysis of aluminium precursors. The characteristics of the resulting materials, such as pore uniformities, porosity and crystalline shape, were investigated. Results show that these methods allow one to prepare tailor-made mesoporous aluminas at an ambient temperature.