Incorporation Of Aluminum Research Articles

Highly efficient selective oxidation of 2-methylnaphthalene to vitamin K3 over mesoporous Al/Ti-SBA-15 catalysts: The effect of acid sites and textural property

Catalytic oxidation of 2-methylnaphthalene to 2-methyl-1,4-naphthoquinone (vitamin K3) is a significant pathway to produce vitamin groups K. High pollution and low-productivity of the traditional method require a greener catalyst and process. In this work, Al/Ti-SBA-15 with different nSi/nAl and nSi/nTi ratios were hydrothermally prepared in mild acidic condition and tested in partial oxidation of 2-methylnaphthalene. Commercial zeolites NaY, β and ZSM-5 were applied to investigate the influence of mass transfer resistance and acidity on catalytic performance. Catalysts were characterized by XRD, N2 adsorption-desorption, TEM, NH3-TPD, FTIR and Py-FTIR. We have found that the 2-methylnaphthalene conversion and vitamin K3 selectivity depend strongly on the mesoporous structure as well as Brönsted acid concentration and strength. Irregular micropores and strong acidity will accelerate the cleavage of C = C in aromatic rings, leading to the production of phthalic anhydride. DFT calculation reveals that incorporation of aluminum in SBA-15 can reduce the energy gap, facilitating the electron transfer. And as a consequence of the substitution of Al in tetrahedral positions in SBA-15, Al-SBA-15 (10) gives the best result with 72% yield to vitamin K3. This catalyst markedly reduces the activation energy due to the modified activated center. Repeated experiments recommend that Al-SBA-15 is a steady and high-efficiency catalyst for the production of vitamin K3.

The Synthesis of Cyclic Carbonates from Oxidative Carboxylation Under Mild Conditions Using Al/FPS Nanocatalyst

By utilizing direct hydrothermal synthesis, catalytic active sites are assembled infibrous framework of phosphosilicate (FPS), controllably. Aluminium (Al) incorporation as a heteroatom at distinct Si/Al ratios is utilized to modify their properties of surface. XRD, XPS, ICP, EDX, TEM, FE-SEM, and BET analyzes are utilized to characteristic catalysts. Converting carbon dioxide (CO2) to cyclic carbonates was suggested as the best approach to produce this C1 building block for the proximity of epoxides. For oxidation carboxylation of styrenes with carbon dioxide, we found that, nanoparticles of Al/FPS are proper catalyst, in one-step reaction. Al/FPS catalytic system in comparison of other reported catalysts can convert various olefins into the synthesis of cyclic carbonates in the highest yields and mild conditions in comparison with the data formerly presented.

Modified phenolic resin with aluminium and rectorite: Structure, characterization, and performance

AbstractPhenolic resin is an important binder for refractory ceramics. Herein, aluminum and organic rectorite were employed to improve the antioxidant activity of phenolic resin. X‐ray diffraction revealed that the silicate layers of phenolic resin exfoliated rectorite were uniformly dispersed in the modified phenolic resin (MPF) matrix. Moreover, TEM revealed that the peeled silicate nanoparticles from rectorite were well distributed without clustering. The structure of the MPF resin was also analyzed by infrared spectroscopy and nuclear magnetic resonance. The results showed that the strength of the ether bridge of MPF resin with aluminum and rectorite considerably decreased than that of pure phenolic resin. The MPF resin was anhydrous and had AlO bonds to link the benzene rings. Pyrolytic carbon experiments revealed that the decomposition temperature of the MPF resin was 759.2°C, which indicated that it had a better oxidation resistance and bonding strength than those of pure phenolic resin. The incorporation of aluminum and rectorite improved thermal performance of the phenolic resin, and enhanced mechanical performance of the MgOC refractory.

Structural evolution and impact on the compressive strength of fly ash-based geopolymers

This paper concentrates on valorization of the fly ash originating from thermal power plant by alkaline activation. Structural and textural characterization of raw material and prepared geopolymers was carried out. The used raw material belonged to Class F according to ASTM C618-05, and it was mainly composed of quartz, mullite, hematite and calcite, that coexisted with hydroxy-sodalite in final geopolymers. The proportion of the hydroxy-sodalite phase increased with the concentration of the activating agent. During geopolymerization, structural changes appeared including the incorporation of aluminum into the silicate network leading to their crosslinking. Textural characterization showed that the material became more compact during the geopolymerization process, which in agreement with the increase of hydroxy-sodalite phase. These changes lead to an increase of mechanical strength of geopolymers.

Effects of Aluminum Incorporation in Tobermorite Structure on Chloride Diffusion: A Molecular Dynamics Simulation Study

In this paper, the effects of different aluminum to silicon ratios in silicate chains of calcium silicate hydrates (C-S-H) are evaluated on the diffusion coefficient of chloride ions by molecular dynamics method. Tobermorite is a crystalline phase that is used for studying C-S-H properties in nano scale, because of its analogous chemical composition to C-S-H. Aluminum incorporation in C-S-H and the formation of calcium aluminosilicate hydrates (C-A-S-H) is due to both of hydration of tricalcium aluminate (C3A) in portland cement and aluminum oxides in pozzolans. There exist different Al/Si ratios in the tetrahedral chains of C-A-S-H depending on available aluminum oxides in cementitious raw materials. In order to compare the simulation results with previously-published experimental researches on cement pastes, a novel method is introduced here to calculate Al/Si ratio in tetrahedral chains of C-A-S-H using pozzolan replacement ratio in cementitious paste. MK (metakaolin) and FC3R (Fluid Catalytic Cracking Catalyst Residue) are the pozzolans that are used to validate the obtained results in this paper. Results showed that diffusion coefficients of chloride ions in C-A-S-H decrease by Al/Si ratio increasing in the tetrahedral chains as it was observed experimentally in previous researches.

Al-Doping of ZnO Thin Films Deposited by Spray Pyrolysis

Undoped and Al-doped zinc oxide (AZO) layers, greatly transparent and with high mobility, have been prepared at low substrate temperature using a chemical reactive spray technique. The effect of aluminum incorporation in the zinc oxide (ZnO) lattice has been characterized by means of X-ray powder diffraction, Raman spectroscopy, electrical and optical measurements. AZO layers reveal a hexagonal wurtzite structure whose lattice parameter decreases with increasing Al content and whose crystal quality decreases for Al content higher than 2%. Low resistivity AZO films have been found for 3% Al content. Additionally, AZO layers exhibit a blue shift of the optical gap with the increase of Al content that is attributed to the Burstein–Moss effect due to the increase of the charge carrier concentration. A density of free electron greater than 2.0 × 1019 cm–3 is obtained for the AZO thin films with 5% Al. Our results encourage the use of AZO films deposited at a low temperature as electrodes and optical windows in photovoltaic devices.

Enhancement of the dispersion and catalytic performances of copper in the hydrogenation of cinnamaldehyde by incorporation of aluminium into mesoporous SBA-15 silica

Copper is active in hydrogenation reactions, but it is a base metal difficult to disperse inside mesostructured supports, with adverse consequences on the catalytic properties. Incorporating aluminium into mesoporous SBA-15 silicas allows solving both problems of Cu dispersion and activity. The incorporation of 20 wt.% Al2O3 in the SBA-15 host structure leads to an increase of the copper metallic surface area by a factor 6 compared to the pure siliceous SBA-15-supported catalyst. The support also proves to be stable upon exposure to the impregnation aqueous solution used for copper introduction. The incorporation of Al provides Lewis acidic sites that favour the transformation of cinnamaldehyde into cinnamyl alcohol, a feature usually assigned to larger metal particles. As a consequence, the catalytic activity of Cu catalysts is enhanced compared to silica-supported Cu catalysts, while the chemoselectivity towards the unsaturated alcohol appears to be similar to that of a mesoporous alumina-supported system.

Low temperature synthesis of garnet solid state electrolytes: Implications on aluminium incorporation in Li7La3Zr2O12

Li ion conducting garnet electrolytes are attracting considerable interest for potential use in all solid state batteries. Nevertheless, their synthesis can be challenging due to the high temperatures required leading to significant Li loss, and consequently the need to add excess Li to counteract this. In this work, we report a low temperature biopolymer sol-gel route to synthesise these garnet materials using Agar (to ensure homogeneous mixing and nucleation through this biotemplating matrix), with the formation of the garnet phase starting at temperatures as low as 600 °C, with single phase samples of tetragonal Li7La3Zr2O12, and cubic Li6.4Al0.2La3Zr2O12 prepared at 700 °C (~ 400 °C lower than the conventional solid state routes). Significantly, this route also allowed the synthesis of these garnets without the need for Li excess for the first time, due to the low temperature limiting Li loss. Moreover, if Li excess was used in the synthesis of cubic Li6.4Al0.2La3Zr2O12, Al incorporation was not observed at this temperature, and rather tetragonal Li7La3Zr2O12 was obtained. Contrary to previous assumptions, this indicates that the Li is more stable in the structure than Al at low temperature. Thus, Al incorporation only occurs if there is a deficiency of Li in the starting material, or if the sample is heated to elevated temperatures to induce Li volatility, so as to drive the incorporation of Al to charge balance the resultant Li loss.

Metal matrix production: Casting of recycled aluminum cans and incorporation of rice husk ash and magnesium

This research experimented with different aluminum can casting compositions from recycled materials. The objective was to analyze the casting yield and the resulting chemical compositions of the process. In the first process, 20 kg of aluminum cans was melted, resulting in a 10.2 kg ingot, which presented a 51% yield. In the second process, 10 kg of 6063 T6 aluminum was used and 10.2 kg of the first casting was added. This mixture produced an ingot of 50% recycled aluminum and 50% 6063 aluminum that weighed 18.23 kg. Similarly, a second ingot was produced, but with the addition of 4 wt% of rice husk ash and 2 wt% of magnesium. From each ingot, the samples were removed for chemical analyses, which consisted of tests of the samples that had the incorporation of rice husk ash in the molten aluminum. These analyses included scanning by electron microscopy, density analysis, Brinell hardness, and Charpy impact force tests. The results of the second ingot analysis showed superior characteristics in Si and Mg levels due to the addition of rice husk ash and magnesium. Also, the second ingot presented increased hardness as well as a reduction fragility and density.

Aluminium distribution in an Earth’s non–primitive lower mantle

The aluminium incorporation mechanism of perovskite was explored by means of quantum mechanics in combination with equilibrium/off-equilibrium thermodynamics under the pressure-temperature conditions of the Earth’s lower mantle (from 24 to 80 GPa). Earth’s lower mantle was modelled as a geochemically non-primitive object because of an enrichment by 3 wt% of recycled crustal material (MORB component). The compositional modelling takes into account both chondrite and pyrolite reference models.The capacity of perovskite to host Al was modelled through an Al2O3 exchange process in an unconstrained Mg-perovskite + Mg-Al-perovskite + free-Al2O3(corundum) system. Aluminium is globally incorporated principally via an increase in the amount of Al bearing perovskite [Mg-Al-pv(80 GPa)/Mg-Al-pv(24 GPa) ≈ 1.17], rather than by an increase in the Al2O3 content of the average chemical composition which changes little (0.11–0.13, mole fraction of Al2O3) and tends to decrease in Al. The Al2O3 distribution in the lower mantle was described through the probability of the occurrence of given compositions of Al bearing perovskite. The probability of finding Mg-Al-perovskite is comparable to Mg-perovskites. Perovskite with Al2O3 mole fraction up to 0.15 has an occurrence probability of ∼28% at 24 GPa, increasing up to ∼43% at 80 GPa; on the contrary, perovskite compositions in the range 0.19–0.30 Al2O3 mole fraction drop their occurrence probability from 9.8 to 2.0%, over the same P-range. In light of this, the distribution of Al in the lower mantle shows that, among the possible Al bearing perovskite phases, the (Mg0.89Al0.11)(Si0.89Al0.11)O3 composition is the likeliest, providing from 5 to 8% of the bulk perovskite in the pressure range from 24 to 80 GPa. The occurrence of the most Al rich composition, i.e. (Mg0.71Al0.29)(Si0.71Al0.29)O3, is a rare event (probability of occurrence < 1.7%). This study predicts that perovskite may globally host Al2O3 in terms of 4.3 and 4.8 wt% (with respect to the non-primitive lower mantle mass), thus accounting for ∼90% and 100% of the bulk Al2O3 estimated in the framework of pyrolite and chondrite reference models, respectively. A calcium-ferrite type phase (on the MgAl2O4-NaAlSiO4 join) seems to be the only candidate that can compensate for the 10% gap of the perovskite Al incorporation capacity, in the case of a pyrolite non-primitive lower mantle model.

Erbium-doped aluminophosphosilicate all-fiber laser operating at 1584 nm.

We report on an ytterbium-free erbium-doped aluminophosphosilicate all-fiber laser, producing an output power of 25 W at a wavelength of 1584 nm with a slope efficiency of 30% with respect to the 976 nm absorbed pump power. The simple cavity design proposed takes advantage of fiber Bragg gratings written directly in the gain fiber. The single-mode erbium-doped aluminophosphosilicate fiber was fabricated in-house and was doped with 0.06mol.% of Er2O3, 1.77 mol.% of Al2O3 and 1.04 mol.% of P2O5. The incorporation of aluminium and phosphorus into the fiber core allowed for an increased concentration of erbium without inducing significant clustering, while keeping the numerical aperture low to ensure a single-mode laser operation.

Role of magnesium and aluminum substitution on the structural properties and bioactivity of bioglasses synthesized from biogenic silica

The objective of this study was to investigate the effect of magnesium (1 wt%) and aluminum (1 wt%) incorporation on the in vitro bioactivity and biodegradation behavior of 45S5 bioactive glasses synthesized from rice husk biogenic silica. The performance of biogenic silica-based samples was compared well with commercial silica-based counterparts. The in vitro biodegradation behavior of bioactive glasses was evaluated by the weight loss of samples and pH variation in the Tris buffer solution. Based on composition, bioglasses possessed different properties before and after simulated body fluid (SBF) immersion. The incorporation of magnesium (Mg) and aluminum (Al) enhanced the Vickers hardness of bioglasses. All the bioglasses showed the hydroxyapatite layer formation after SBF treatment as confirmed by the dissolution, FTIR, SEM and XRD analysis, however it was more prominent in the rice husk silica-based 45S5 bioglass. The biogenic silica seems to be a promising starting material for bioglass systems to be used in bone tissue engineering applications.

Pulsed-flow growth of polar, semipolar and nonpolar AlGaN

The impacts of pulsed-flow growth on aluminium incorporation in polar (0001), semipolar (101̄3) and (112̄2), as well as nonpolar (101̄0) AlGaN layers have been investigated.

Aluminum incorporation into magnesium silicate hydrate (M-S-H)

The incorporation of aluminum in magnesium silicate hydrate (M-S-H) phases was investigated. Magnesium (alumino) silicate hydrate (M-(A-)S-H) with Mg/Si ratios equal to 1.1 or 1.7 and Al/Si ranging from 0 to 0.2 were synthetized in batch experiments and equilibrated at 20, 50 and 70 °C. pH values between 9 and 10.5 were observed and aluminum up to Al/Si ~0.15–0.18 was incorporated in M-(A-)S-H. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray pair distribution function (PDF) analysis, transmission electron microscopy (TEM), 29Si and 27Al MAS NMR data showed that the M-(A-)S-H phases formed were similar to M-S-H with limited coherent size and a comparable polymerization degree of the tetrahedral silicates. Aluminum was incorporated in both tetrahedral and octahedral sites of M-S-H, while no aluminum was present as exchangeable cation on the surface sites.

Preparation and Characterization of Agar Based Magnetic Nanocomposite for Potential Biomedical Applications.

The purpose of the present study was to make a biocompatible agar based composite material via incorporation of appropriate additives within the agar matrix for potential applications in drug delivery and biomedical fields. Agar based composites were prepared by the incorporation of magnetic iron oxide nano particles, graphite and sodium aluminum as additives in different proportions within the agar matrix by a simple thermophysico- mechanical method. The as prepared agar based composites were then characterized by different techniques i.e. FTIR, SEM, TGA, XRD and EDX analyses. The FTIR peaks confirmed the presence of each component in the agar composite. SEM images showed the uniform distribution of each component in the agar composite. TGA study showed the thermal stability range of different composite sheets. XRD pattern revealed the crystallinity and EDX analysis confirmed the elemental composition of the prepared composites. The prepared agar based composites were evaluated for antimicrobial activities against three pathogenic bacterial strains Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia and the result indicated efficient antimicrobial activities for all composites. From the overall study, it was concluded that due to the non-toxic nature, thermal stability and excellent antibacterial properties, the prepared agar based composites can receive potential biomedical applications.

Effect of kaolin on aluminum loading success in synthesis of Al-SBA-15 catalysts: Activity test in ethanol dehydration reaction

Abstract Aluminum incorporated SBA-15 catalysts were prepared via hydrothermal method using together with aluminum salt and kaolin as aluminum source. Aluminum loading to the SBA-15 structure did not destroy the characteristic peaks of SBA-15 (from X-Ray diffraction (XRD) patterns) and it was led to increase of surface area values. Energy dispersive spectroscopy (EDX) and inductively coupled plasma optical emission spectroscopy (ICP-OES) results demonstrated that increase of kaolin amount positively affected the success of aluminum loading. UV–visible diffuse reflectance (UV–Vis DR) and X-ray photoelectron spectroscopy (XPS) spectra showed that aluminum species were settled in the form of metal oxide. Fourier transform infrared (FTIR) spectra exhibited the characteristic structural bands of SBA-15. Generally the peak intensities of the acid sites increased slightly with the aluminum incorporation and this increase showed mostly at Lewis acid sites. The highest ethanol conversion and ethylene selectivity was observed as 0.95 and 1.00 at 400 °C, respectively.

Aluminium incorporation in polar, semi- and non-polar AlGaN layers: a comparative study of x-ray diffraction and optical properties

Growth of AlxGa1−xN layers (0 ≤ x ≤ 1) simultaneously on polar (0001), semipolar (10bar{{rm{1}}}3) and (11bar{{rm{2}}}2), as well as nonpolar (10bar{{rm{1}}}0) and (11bar{{rm{2}}}0) AlN templates, which were grown on planar sapphire substrates, has been investigated by metal-organic vapour phase epitaxy. By taking into account anisotropic in-plane strain of semi- and non-polar layers, their aluminium incorporation has been determined by x-ray diffraction analysis. Optical emission energy of the layers was obtained from room-temperature photoluminescence spectra, and their effective bandgap energy was estimated from room-temperature pseudo-dielectric functions. Both x-ray diffraction and optical data consistently show that aluminium incorporation is comparable on the polar, semi- and non-polar planes.

Cobalt-Based Fischer–Tropsch Synthesis: A Kinetic Evaluation of Metal–Support Interactions Using an Inverse Model System

Metal–support interactions in the cobalt–alumina system are evaluated using an inverse model system generated by impregnating Co3O4 with a solution of aluminum sec-butoxide in n-hexane. This results in the formation of nano-sized alumina islands on the surface of cobalt oxide. The activated model systems were kinetically evaluated for their activity and selectivity in the Fischer–Tropsch synthesis under industrially relevant conditions (220 °C, 20 bar). The kinetic measurements were complemented by H2-chemisorption, CO-TPR, and pyridine TPD. It is shown that the introduction of aluminum in the model system results in the formation of strong acid sites and enhanced CO dissociation, as evidenced in the CO-TPR. The incorporation of aluminum in the model systems led to a strong increase in the activity factor per surface atom of cobalt in the rate expression proposed by Botes et al. (2009). However, the addition of aluminum also resulted in a strong increase in the kinetic inhibition factor. This is accompanied by a strong decrease in the methane selectivity, and an increase in the desired C5+ selectivity. The observed activity and selectivity changes are attributed to the increase in the coverage of the surface with carbon with increasing aluminum content, due to the facilitation of CO dissociation in the presence of Lewis acid sites associated with the alumina islands on the catalytically active material.

Tuning of activity and selectivity of Ni/(Al)SBA-15 catalysts in naphthalene hydrogenation

The hydrogenation of naphthalene was performed with nickel catalysts (4 wt. % of Ni) supported on SBA-15 and Al-SBA-15 in order to evaluate the effect of the support’s acidity on the activity and selectivity of the catalysts. The incorporation of aluminum into the SBA-15 support was performed during the hydrothermal synthesis of the material with the aim to reach the isomorphic substitution of Si4+ by Al3+ leading to the generation of Brönsted acid sites. Two different precursors (nickel nitrate and a Ni:EDTA complex) were used for the preparation of the catalysts on each support. Catalysts were characterized by nitrogen physisorption, powder X-ray diffraction, temperature programmed reduction, temperature programmed desorption of ammonia, scanning and high-resolution transmission electron microscopy. The Al-SBA-15 support was characterized by solid state 27Al MAS-NMR. The results showed that the intrinsic activity of the catalysts (TOF) increased when the Al-SBA-15 support and the Ni:EDTA complex were used in the catalyst’s preparation. The catalysts prepared using the Ni:EDTA complex showed high selectivity to decalins and higher proportion of trans-decalin in the products than the catalysts prepared with nickel nitrate, which was attributed to a higher dispersion of the metallic Ni species and the larger total amount of acid sites.

Aluminium introduction on the STF zeolite synthesized with the organic structure-directing agent 123TE4MI

In this research work we studied the structure-director effect of the organic compound 1,2,3-triethyl-4-methylimidazolium in the synthesis of zeolitic aluminosilicates following the fluoride route. One-phase STF products were obtained, having a morphology similar to thin long sticks. We also studied the influence of the Si/Al gel ratio variations. The aluminium incorporation was proven by solid-state nuclear magnetic resonance, a bulk technique, and a comparison with a surface technique, such as X-ray photoelectron spectroscopy, was performed. The results of the first technique showed the presence of various aluminium coordination in different proportions, reporting for the first time the resonances between 10–30 ppm in the aluminium spectrum for this zeolitic topology. Meanwhile, by the second technique, the octahedral and tetrahedral aluminium were the only observed at the surface. The results showed in this article intent to help controlling the introduction of aluminium for future applications, such as catalysis.