A variety of methods are employed to synthesize amorphous silica–alumina (ASA) to resolve the role of Al speciation and surface area in the catalytic performance in the Diels–Alder cycloaddition…
The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than the ...
1. Introduction. Alumina is an original critical material for defense construction and economic development, with applications in aircraft, electrical electronics, construction, materials, chemical medicine, and other fields [1], [2], [3], [4].The established global system for the alumina industry reached over 135 million tons in 2021 [5], [6].More than 95% of …
A thin layer (30–40 nm) of a dual-element silica–alumina composition was deposited on a porous alumina support by chemical vapor deposition (CVD) in an inert atmosphere at high temperature. Prior to CVD, an intermediate layer of γ-alumina was coated on the macroporous alumina support. The intermediate layer was prepared by …
Afterwards, low-temperature alkaline leaching and Bayer digestion extracted 87% of silica and 89% of alumina, respectively. However, the poor separation effect of Si and Al is attributed to the ...
In this work a water vapor-permselective alumina–silica composite membrane reactor is proposed to overcome the thermodynamic equilibrium limitations and increasing catalyst activity. A steady state heterogeneous model is developed to simulate the proposed configuration. ... Simultaneous occurrence of reaction and separation …
From the discussion in Section 1, alumina production from by-products of HAC is infeasible by directly using Bayer process due to the low A/S (~1.0); therefore, the key issue of alkali extraction of alumina is an efficient separation of alumina and silica in …
Alkali leaching was employed to investigate the separation of alumina and silica in roasted kaolin obtained by roasting kaolin alone in air at 1273 K for 60 min and in clinker prepared by roasting the mixed raw meal of kaolin, ferric oxide and coal powder with Fe 2 O 3 /Al 2 O 3 /C molar ratio of 1.2:2.0:1.2 in reducing atmosphere at 1373 K for 60 …
The efficient and economical separation of alumina/silica minerals is critical to alumina production. In this work, selective surface magnetization was adopted to separate alumina-/silica-bearing minerals. The zeta potentials of boehmite, quartz, and magnetite with and without 100 ppm sodium fluoride (NaF) were measured. Results …
pre-separation of silica from low A/S (mass ratio of alumina to silica) bauxite in order to offer qualified raw materials for the Bayer alumina refinery. Several typical methods have been proposed for the pretreatment of bauxite, such as flotation dressing [1−4], direct wet treatment [5] and roasting−leaching process [6−8].
A thin high-silica MEL membrane was synthesized on a porous α-alumina hollow fiber support by a secondary growth approach.The membrane quality was evaluated by permporometry, single-gas permeation and butane isomer separation.
DOI: 10.1016/j.cej.2024.148788 Corpus ID: 266988662; Silica-alumina zeolite adsorbents for oxygen generation via pressure swing adsorption: Mechanisms and challenge @article{Yu2024SilicaaluminaZA, title={Silica-alumina zeolite adsorbents for oxygen generation via pressure swing adsorption: Mechanisms and challenge}, author={Qingjun …
Silica or alumina. Pasteur pipette. Method: Fill the column about one third with solvent (Fig. 6, step B). In a beaker, measure out the required amount of silica or alumina. In a separate flask or beaker, measure solvent approximately one and a half times the volume of silica. Add the silica to the solvent, a little at a time, while swirling.
Request PDF | On Oct 1, 2015, Xiaobin Li and others published Preliminary results on selective surface magnetization and separation of alumina-/silica bearing minerals | Find, read and cite all ...
The applications of silica-aluminas in industrial catalytic processes are briefly reviewed. The literature data on the surface chemistry and structural chemistry of …
Here we report immobilization of glucose oxidase (GOx) on magnetic silica (Fe 3 O 4-SiO 2) and alumina (Fe 3 O 4-Al 2 O 3) functionalized with amino groups using glutaraldehyde as a linker.Magnetic support based biocatalysts demonstrate high catalytic activity in d-glucose oxidation to D-gluconic acid at pH 5-7.5 and temperature of 30-50 °C with the …
The stationary phase is an adsorbent powder or gel such as silica gel or alumina. Silica gel and alumina are highly polar so they interact strongly with polar compounds and solvents, and weakly with nonpolar molecules. ... To start the separation, add the sample to the column without disturbing the sand. Use small portions of solvent to rinse ...
From the discussion in Section 1, alumina production from by-products of HAC is infeasible by directly using Bayer process due to the low A/S (~1.0); therefore, the key issue of alkali extraction of alumina is an efficient separation of alumina and silica …
In this paper, a technique for comprehensive extraction of silica and alumina from circulating fluidized bed-based CFA is presented. The method involves reduction …
The separation of alumina and silica in clinker was carried out by alkaline leaching in 160 g/L NaOH solution with solid/liquid of 5 g/50 mL at 110 °C for 180 min. Fig. 8 shows that the silica leaching ratio is about 95% and nearly unchanged when treating the clinker of RCG-800 °C and RCG-900 °C, and the corresponding A/S in the leached ...
Different separation technologies used to remove silica and alumina from low-grade iron ores were reviewed. The major concentration methods that may be applied to upgrade …
Efficient removal of silica is the key to alumina extraction from coal fly ash (CFA) by the Bayer process, due to the easy formation of sodium aluminosilicate hydrates during alkaline digestion. Considering the main mineral of well-crystallized mullite in CFA, mechanical activation was used in this work to improve the silica removal during …
In this paper, we verify the separation effect of alumina and silica in CFB-derived coal fly ash by hematite involved roasting-alkaline leaching-Bayer digestion. The …
The XRD diagram of alumina-rich coal is provided in Figure 1. The envelope at around 25° can be attributed to the carbon in coals, and kaolinite (PDF …
Elaboration from clay (kaolin, mixtures of clay and alumina): mullite is obtained by reaction between silica and alumina present in the clay. The firing temperature ranging between 1200 and 1400 °C. Elaboration from sillimanite minerals and bauxite: This type of refractory is characterized by its high refractoriness, good mechanical strength ...
The filtrates after separation were analyzed in Figure 6, in which the concentrations of alumina, silica and Na 2 O in the filtrates decreased very rapidly with the addition of concentrated H 2 SO 4, for …
Also, it is worth mentioning that gases permeability tendency for the modified alumina support membrane, have changed from H 2 >CH 4 >CO 2 > CO to H 2 >CO 2 >CO > CH 4 for silica-zirconia CVD coated membranes.This phenomenon is in good agreement with the molecular size of the gases (H 2 = 0.289 nm, CO 2 = 0.33 nm, CO = …
The utilization of coal fly ash has been of great concern in recent years due to the growing awareness of waste recycling and environmental protection. Alumina recycling from coal fly ash is a good path to realize the state-of-the-art utilization of coal fly ash. The present work proposes a novel strategy for recovering alumina and producing …
Alumina Silica Carbon Porous polymers Porous polymers Silica Porous polymers Select Perm. Gases Select Low Sulfur Porous polymers Silica Lowox OxyPLOT 18 July 31, 2014 . ... • Poor C4 isomer separation Alumina preferred • Not sensitive to moisture • Good choice for solvents and CFCs 19 July 31, 2014 .
The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than …
After magnetic separation, the alumina content, silica content, and the mass ratio of alumina/silica in the non-magnetic part of the separation product was 80.36 wt%, 6.49 wt%, and 12.38 ...
Wu et al. synthesized alumina-silica with an enhanced mesoporosity and acidity by the sol-gel method accompanied in the presence of C 16 EO 10 acting as ... Silica-alumina catalyst with bimodal pore structure prepared by phase separation in sol-gel process. J Catal, 200 (2001), pp. 197-202, 10.1006/jcat.2001.3196. View PDF View …
In this paper, a technique for comprehensive extraction of silica and alumina from circulating fluidized bed-based CFA is presented. The method involves reduction …
As in the silica system, pure alumina-based aerogels are usually obtained with synthetic alumina precursors, with aluminum alkoxides and aluminum salts being the most used compounds [22,23]. Alumina aerogels are nanoporous materials with low density (~0.035–0.4 g cm −3 ), high porosity and high surface area (350–700 m 2 g −1 ) …