Metal Oxide Ratios Research Articles

Enhanced conversion of a magnetic oxide to metal using induction heating: Application for H2 production

In this study, a C–CoFe2O4 composite is proposed for reduction in an induction heating reactor with a continuous argon flow. An impressive conversion efficiency of 87% is achieved at a maximum temperature of 325 °C in just 8 min without the need for vacuum. The impact of the molar ratio of metal oxide to reducing agent (acetylacetone) is also examined. Results indicate that a 1:1 ratio favours the reduction towards cobalt and iron monoxides, while a 1:3 ratio yields a 31% metal phase. The highest conversion (87%) is seen with a 1:17 ratio, indicating the need for excess reducing agent for effective conversion of CoFe2O4 oxide. The molar ratio influences the induction heating temperature, with the 1:17 ratio having a lower temperature of 325 °C compared to 450 °C for other ratios. These operating temperatures (≤450 °C) are significantly lower than those reported in the literature for carbothermal reduction in an induction reactor (>1700 °C), which often requires vacuum and very high temperatures for high conversion efficiency. The proposed process offers advantages such as high conversion efficiency, fast processing, and simpler operational conditions. Additionally, the metallic phases produced are utilized for H2 production in thermochemical water splitting, showcasing these materials potential for energy generation applications.

Syngas production from dry reforming of glycerol by the NiO/M-Al2O3 catalysts: Effect of various support promoters and various ZrO2 content

Glycerol dry reforming presents an intriguing approach for converting CO2, a greenhouse gas, and glycerol, a renewable resource, into syngas. This study delves into the impact of introducing 5 wt% of ZrO2, CeO2, La2O3, and Y2O3 to the Al2O3 support. Additionally, the study examines the influence of the optimal metal oxide ratio within the support formula on both structural properties and catalytic performance in the glycerol dry reforming process. To investigate these aspects, various catalyst supports were synthesized using a mechanochemical method. Subsequently, nickel-based catalysts were prepared through a wet impregnation technique. The catalysts underwent comprehensive characterization employing techniques such as XRD, BET, H2-TPR, CO2-TPD, TPO, and FESEM analyses to determine their physicochemical properties. The results demonstrated that the sample enhanced with 5 wt% ZrO2 exhibited remarkable performance metrics. Notably, it achieved a catalytic activity of 85.4% glycerol conversion at 650 ℃, while also displaying better stability and resistance to carbon deposition compared to the unpromoted catalyst throughout a 600 minutes reaction period. These enhanced attributes were attributed to the heightened specific surface area of the support (241.95 m2/gr), the effective dispersion of Ni on the support and the increase in basic sites.

Modeling and prediction of thermal conductivity ratio of metal-oxide based nano-fluids using artificial neural network and power law

Modeling and prediction of thermal conductivity ratio of metal-oxide based nano-fluids using artificial neural network and power law

Preparation of Tc-NpO2 metal-ceramic compositions and their imitators (Re, Th, Nd) for long-term safe storage of long-life fission products

The preparation routes for ceramic-metal matrices (CMM) Tc-NpO2 and their imitators Tc(Re)-ThO2 and Tc(Re)-Nd2O3 with different metal-oxide ratios has been investigated and the physical and chemical properties (such as leaching, thermal stability) of the products were determined. The structure of [Np(H2O)3(TcO4)4]×H2O has been determined by single crystal X-ray diffraction analysis. Thermal decomposition of neptunium pertechnetates (IV and VI) as well as their imitators neodymium and thorium perrhenates were considered in detail. The surface morphology for CMM Tc-NpO2 and the leaching rate of each radionuclide was experimentally determined.

Exploring a monotonically non-decreasing behavioral function on shielding properties and transmission factors in borosilicate glasses through heavy metal oxide reinforcement

In this study, the gamma-ray attenuation properties and transmission factors of different types of glasses formed in the (B2O3)x[(ZnO)0.60-(SiO2)0.40]1-x system as a function of increasing heavy metal oxide ratio were investigated. For transmission factor and absorption coefficient calculations, the general-purpose Monte Carlo code MCNPX (2.7.0) was used. In addition, the Phy-X/PSD code is used to obtain some important gamma-ray shielding parameters. According to the obtained results, increasing the quantity of heavy metal oxide in the glass composition favorably affected the examined parameters and lowered the transmission factor and buildup factor values. Furthermore, it has been observed that parameters such as the absorption coefficient and the effective atomic number increase as a function of increasing heavy metal oxide contribution into glass configuration. The lowest half value layer values are reported for S1 sample. For example, half value layers are reported as 3.313 cm, 3.449 cm, 3.764 cm, 3.625 cm, 3.515 cm for S1, S2, S3, S4, and S5 sample at 1 MeV photon energy, respectively. According to the transmission factor values, S1 is the sample that allows the least transmission of primary photons and demonstrates the highest resistance. It was observed that the minimal exposure build-up factor and energy absorption buildup factor values for the S1 sample at 10 mean free paths. It can be concluded that the heavy metal oxide additive applied to borosilicate glasses creates a non-decreasing functional behavior effect that is monotonic in gamma-ray attenuation parameters.

Ti, F Codoped Sodium Manganate of Layered P2-Na 0.7 MnO 2.05 Cathode for High Capacity and Long-Life Sodium-Ion Battery

Ti, F Codoped Sodium Manganate of Layered P2-Na _0.7 MnO _2.05 Cathode for High Capacity and Long-Life Sodium-Ion Battery

Design and characterization of frog egg shaped CoFe2O4@C core-shell composite as a novel multi-functional counter electrode for low-cost energy devices

The electrical conductivity and catalytic activity of the electrode materials greatly affect the photoelectric conversion performance of DSSCs. However, the commonly used Pt electrodes no longer meet the needs of long-term development at present. Herein, based on the Kirkendall effect, CoFe 2 O 4 @C nanoparticles with core-shell structure are successfully prepared using the treatment of quasi-sol-gel method. The size of CoFe 2 O 4 @C nanoparticles is homogenized without agglomeration through adjusting the ratio of metal salt in the precursor. The composite exhibits excellent counter electrode properties in DSSCs, which attributes to the large specific surface area and superior electro-catalytic activity. With the optimized film thickness (12 µm) of CoFe 2 O 4 @C, an excellent photoelectric conversion efficiency of 7.80% is finally achieved, significantly higher than that of pure carbon (PC) electrode (6.36%) and even Pt counter electrode (7.05%) under the same conditions. The composite can additionally catalyze the recycling of I - /I 3 - redox couple steadily, providing more possibilities for the study of Pt-free materials about DSSCs counter electrode. Through the simple quasi sol-gel method, the carbon material with good conductivity and CoFe 2 O 4 with excellent catalytic activity are tactfully combined to form stabile CoFe 2 O 4 @C nanoparticles with core-shell structure, which are successfully applied to DSSCs counter electrodes. The photoelectric conversion performance of DSSCs is greatly improved by utilizing the sufficient specific surface area of the composite material and its stable catalytic ability to electrolyte cycle. A PCE of 7.80% is achieved literally with the further optimization of adjusting the carbon-transition metal oxide ratio and the film thickness of CoFe 2 O 4 @C-based CE, which is enhanced by 11% and 23% than that of Pt (PCE=7.05%) and pure carbon (PCE=6.36%). This attempt provides a new idea and reference for further optimization of DSSCs. • A core-shell structure CoFe 2 O 4 @C composite was prepared efficiently by quasi-sol-gel method based on the Kirkendall effect. • The composite combines the superior conductivity of the carbon shell with the good catalysis of the CoFe 2 O 4 core. • A PCE of 7.80% is achieved with the optimization of the ratio of C and CoFe 2 O 4 and the thickness of CoFe 2 O 4 @C-based CE.

Facile synthesis of a binary composite from watermelon rind using response surface methodology for supercapacitor electrode material

The electrode material is critical to the performance of a supercapacitor. Therefore, developing a cost-effective and efficient electrode is an essential step toward broader applications for energy storage devices. This paper reports the development of a novel binary composite from watermelon rind (BCWR) as a nitrogen-rich and high stability precursor for a supercapacitor's electrode. BCWR has been successfully synthesized via one-pot self-purging pyrolysis of watermelon rind waste impregnated with nickel ferrite (NiFe2O4). The effects of process parameters such as pyrolysis temperature, pyrolysis time and biomass to metal oxide ratio were investigated by response surface methodology (RSM). The statistical analysis showed the optimal synthesis condition for BCWR to be 600 °C pyrolysis temperature, 15 min pyrolysis time, and 75:25 ratio of watermelon rind (WR) to NiFe2O4. Furthermore, the predicted model and experimental results for the specific capacity of BCWR were determined to be 191 Cg−1 and 187 Cg−1 at 5 mV s−1. With the experimental validation based on structural, chemical and morphological and electrochemical properties determined by X-Ray Diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), field emission electron scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectrometry (EIS) we find that watermelon rind biochar (WRB) and BCWR can be considered as a superior alternative for electrode materials for energy storage applications. Two-electrode cells device configuration of BCWR/WRB supercapattery exhibited high power density and energy density of 750.00 W kg−1 and 28.33 Wh kg−1 respectively at 1 Ag−1 current density. Besides, the calculated charge transfer resistance of the BCWR/WRB supercapattery is 42.35 Ohms.

Facile Preparation of Carbon Nitride-ZnO Hybrid Adsorbent for CO2 Capture: The Significant Role of Amine Source to Metal Oxide Ratio

The presence of CO2 in gaseous fuel and feedstock stream of chemical reaction was always considered undesirable. High CO2 content will decrease quality and heating value of gaseous fuel, such as biohydrogen, which needs a practical approach to remove it. Thus, this work aims to introduce the first C3N4-metal oxide hybrid for the CO2 cleaning application from a mixture of CO2-H2 gas. The samples were tested for their chemical and physical properties, using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), physical adsorption analysis (BET), fourier-transform infrared (FTIR), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The CO2 capacity test was carried out by means of a breakthrough test at 1 atm and 25° C using air as a desorption system. Among the samples, amine/metal oxide mass ratio of 2:1 (CNHP500-2(2-1)) showed the best performance of 26.9 wt. % (6.11 mmol/g), with a stable capacity over 6 consecutive cycles. The hybrid sample also showed 3 times better performance than the raw C3N4. In addition, it was observed that the hydrothermal C3N4 synthesis method demonstrated improved chemical properties and adsorption performance than the conventional dry pyrolysis method. In summary, the performance of hybrid samples depends on the different interactive factors of surface area, pore size and distribution, basicity, concentration of amine precursors, ratio of amines precursors to metal oxide, and framework stability.

Synthesis of Al/Fe Pillared Bentonite: Characterisation and Analysis of Thermodynamic Parameter

The modification of bentonite by pillarization process of Al/Fe metal oxide has been carried with metal oxide with ratios 1:2 and 2:1. The product was characterized by FT-IR, XRD and pHpzc analysis. Thus, this optimal pillarization product was used as an adsorbent of Congo red and Direct green dyestuffs. The FTIR characterization does not show optimum pillarization processes for any metal oxide ratios, while the XRD analysis shows the optimum pillarization processes at ratio 2:1 i.e. 17.1 Å. In addition, the optimum pH for absorption of Congo red took place at 2 while for Direct green at 3. At 70oC, the highest adsorption capacity (Qe) reached 57.34 and 72.06 mol/g; and the highest adsorption energy (E) was found 3.23 kJ/mol and 4.14 kJ/mol for Direct green for Congo red and Direct green, respectively. Vice versa, the enthalpy (ΔH) and entropy (ΔS) values decreased as the increase of both Congo red and Direct green concentration.

Fabrication of porous Al2O3–MgO–TiO2 ceramic monoliths by the combination of nanoemulsion templating and temperature-induced forming

Porous ceramics have attracted considerable attention owing to the increased interest in their applications. Porous Al2O3–MgO–TiO2 ceramic monoliths were synthesized using nanoemulsion templating and temperature-induced forming method. The nanoemulsion (NE) is prepared by the phase inversion composition method. The ceramic slurry was dispersed by ammonium citrate trihydrate (ACT), and polyacrylic acid was used to induce gelling. The effect of different nanoemulsions and different metal oxide ratios on the fired monoliths were studied. The suspended ceramic, green bodies and fired monoliths were characterized by different characterization techniques. The combination of NE with ACT increases the zeta potential of ceramic slurries to ∼−28 mV. The combined routes successfully resulted in porous monoliths with an ironic microstructure with a homogenous distribution of pores. The apparent porosity increased to 57 % that in turn increased resistivity to 4.41E + 10 Ω.cm. The fired monoliths have corundum, rutile, spinel and aluminum titanate phases.

Biodiesel production via simultaneous transesterification and esterification reactions over SrO–ZnO/Al2O3 as a bifunctional catalyst using high acidic waste cooking oil

A simultaneous transesterification and esterification process was applied for production of biodiesel from high acidic waste cooking oil containing 18 wt% FFA using a range of heterogeneous bifunctional strontium–zinc–aluminium catalyst. The influence of the molar ratio of metal oxide, the ethanol to waste oil molar ratio, temperature and time of reaction, catalyst dosage, and free fatty acids in the feedstock on the conversion of biodiesel were studied. High interaction between Sr, Al and Zn metal was recognised to promote catalyst performance. A high interaction and mixing of strontium, aluminium and zinc oxides enhanced and increased the active sites on the surface of acid and base. The catalyst with a 2.6:1 M ratio of strontium to zinc was found to perform the best to transesterify the glycerides and esterify the fatty acid in the used oil simultaneously. The catalyst exhibited higher catalytic activity with high acidity waste cooking oil, with 95.7% reaction conversion at the optimum conditions 10:1 ethanol to waste oil molar ratio, 15 wt% catalyst dosage, and 5 h reaction time at 75 °C reaction temperature. The used catalyst showed low reusability due to high leaching of strontium.

Synthesis of novel Sn1-xZnxO-chitosan nanocomposites: Structural, morphological and luminescence properties and investigation of antibacterial properties

In recent times, metal oxide-organic nanocomposites have received great attention because of their feasibility to wide range applications such as super capacitors, antibacterial activity, biomedical sensors, battery applications and microfluidic devices. In this work, zinc oxide-chitosan (ZnO-CS) and their novel tin zinc oxide-chitosan (Sn1-xZnxO-CS) hybrid nanocomposites successfully synthesized by a simple one-pot sol-gel reaction. The equal metal oxide ratio such as 0.5, 1.0, 1.5 and 2.0% (W/V) for zinc and tin sources with constant weight of chitosan were used to prepare the Sn1-xZnxO-CS nanocomposites. Fourier transform infrared spectroscopy results proved the formation of Sn1-xZnxO-CS nanocomposites. X-ray diffraction patterns discovered the mixed phase polycrystalline nature of Sn1-xZnxO-CS nanocomposites. Optical and luminescence properties were extensively studied for nanocomposites by UV–Vis and photoluminescence spectroscopy, respectively. The surface modification elaborately discussed with scanning electron microscope images due to incorporation of SnOx with ZnO-CS matrix. The antibacterial properties of Sn1-xZnxO-CS were tested against Escherichia coli, Salmonella Typhi and Klebseilla Pneumoniae bacterial species.

Sintering and concomitant crystallization of bioactive glasses

AbstractThe sintering of bioactive glasses allows for the preparation of complex structures, such as three‐dimensional porous scaffolds. Such 3D constructs are particularly interesting for clinical applications of bioactive glasses in bone regeneration, as the scaffolds can act as a guide for in‐growing bone cells, allowing for good integration with existing and newly formed tissue while the scaffold slowly degrades. Owing to the pronounced tendency of many bioactive glasses to crystallize upon heat treatment, 3D scaffolds have not been much exploited commercially. Here, we investigate the influence of crystallization on the sintering behavior of several bioactive glasses. In a series of mixed‐alkali glasses an increased CaO/alkali metal oxide ratio improved sintering compared to Bioglass 45S5, where dense sintering was inhibited. Addition of small amounts of calcium fluoride helped to keep melting and sintering temperatures low. Unlike glass 13‐93, these new glasses crystallized during sintering but this did not prevent densification. Variation in bioactive glass particle size allowed for fine‐tuning the microporosity resulting from the sintering process.

Recent Ferroalloy Studies at Istanbul Technical University

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Production of Iron Based Alloys from Mill Scale through Metallothermic Reduction

AbstractMill scale (MS) has a potential to use as an iron source because of its high iron content. MS mainly consists of a mixture of iron oxides, metallic iron and other base metal oxides. MS is formed on the surfaces of steel ingots during continuous casting as a waste material. In this study, the use of MS as an iron source for the production of carbon-free iron containing alloys (unalloyed iron, Fe-Ni, Fe-Cr-Ni, Fe-Cr-Ni-Mo) via a metallothermic reduction process was investigated. Thermodynamic calculations and the experimental studies were performed on the basis of 100 g of MS. The effects of different stoichiometric amounts of MS and aluminum (Al) powders (as reductant) were investigated for the production of unalloyed Fe. While, different amount of metal oxide ratios and their effects on metal recoveries, compositions and microstructure of final alloys were studied during Fe-based alloys production. The highest iron recovery during unalloyed Fe production was obtained as 95.14 % by using 100 g of MS and 100 % stoichiometric Al (28.6 g) containing mixture. In Fe-based alloys production series, the highest metal recovery values were reached up to 95.0 % for Fe, 95.1 % for Ni, 68.3 % for Cr and 77.2 % for Mo, respectively.

Methanol oxidation in dry and humid air by dielectric barrier discharge plasma combined with MnO2–CuO based catalysts

Presence of humidity in polluted gas streams is a key parameter to give a realistic view of a depollution process efficiency. With this in mind, the elimination of methanol by non thermal plasma in presence of a MnO2-CuO based catalyst and 35% relative humidity (20 °C, atmospheric pressure) was achieved. The reactor allows the treatment of low concentration pollutants (25–200 ppm) at weak residence time (0.36 s) in air at atmospheric pressure. Based on conversion rate and CO2 selectivity, a 5% MnO2/5% CuO/Al2O3 catalyst was selected within an array of catalysts prepared by different impregnation methods with various metal oxide ratios. The presence of humidity affected methanol conversion, ozone concentration and selectivities to by-products. Beneficial effects of humidity were observed on by-products elimination and CO2 selectivity despite a lower methanol conversion compared to dry air conditions.

Hydrodesulfurization of Thiophene on Activated Carbon Fiber Supported NiMo Catalysts

Activated carbon microfiber (ACF)-supported NiMo-based catalysts were prepared for the hydrodesulfurization (HDS) of thiophene. The catalysts were characterized for their physicochemical properties, using the Brunauer–Emmett–Teller, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, temperature-programmed reduction, and temperature-programmed desorption analysis. The effects of the NiO (promoter)-to-MoO3 (active metal oxide) ratios were experimentally determined on the HDS of thiophene (3% v/v in hydrogen) over the temperature range of 300–370 °C. The catalytic activity tests showed the optimum reaction temperature and weight ratio of NiO to the binary oxide mixture to be 350 °C and 0.25 at 12% (w/w) loading of MoO3, respectively. The pseudo-first order rate constant and activation energy for the HDS reaction were determined to be 980 × 10–6 mole thiophenes/gram catalyst min–1 and 46.3 kJ/mol, respectively, which were greate...

Importance of microstructure and interface in designing metal oxide nanocomposites for supercapacitor electrodes

In this work, we demonstrate that designing metal oxide nanocomposite with an optimized nanocarbon to metal oxide ratio is required to realize the best electrochemical performance. Using carbon nano-onion (CNO) and TiO2 composite as a model system, it is evidenced that the formation of interfacial structure and the existence of electrical percolation networks are essential to enhance electrical performance of the composite. When the aforementioned conditions are satisfied, CNO/TiO2 hybrid nanocomposites (CTHNs) with only 11wt% TiO2 loading exhibits excellent electrochemical performance. The maximum specific capacitance obtained for this composite electrode is 386Fg−1 at a scan rate of 5mVs−1, which is the highest reported value till date in a TiO2 composite electrode measured in a two electrode cell configuration. At this composition, excellent electrochemical stability is obtained with only 5% capacitance degradation over 2000cycles. As the TiO2 loading increases the electrochemical performance decreases.

Facile Redox Synthesis of Layered LiNi1/3Co1/3Mn1/3O2 for Rechargeable Li-ion Batteries

The present work reports on the development of layered-type Lix(Ni1/3Co1/3Mn1/3)O2 (x=1.05 and 1.1) cathodes by a simple ambient temperature redox synthesis followed by post-heat treatments with added lithium source. The intermediate precursor (Ni1/3Co1/3Mn1/3Oy) was synthesized through redox reaction between KMnO4, CoCl2 and NiCl2 in aqueous KOH medium. Synchrotron XANES and ICP measurements were performed to confirm the changes in the oxidation states and successful control in stoichiometric ratio of ternary transition metal oxide (Ni2+0.33Co3+0.35Mn4+0.32Oy) during the redox reaction. Synchrotron X-ray diffraction studies of post lithiation confirmed the formation of a well-developed layer-type hexagonal phase of α-NaFeO2 with least cation mixing, as observed from the estimated lattice parameters (a=2.858Å and c=14.228Å), integrated intensity ratio (I003/I104=1.79), and c/3a ratio (∼1.659) values. FE-SEM images revealed loosely agglomerated particles with average diameters of 60nm in the intermediate product while the particle-size grows to a few hundred nanometers after lithiation at elevated temperatures. The electrochemical performances in the potential range of 3.0–4.3V vs. Li/Li+ at 14 mAg−1 indicated that reasonable specific capacities and cycle performances are registered for all the prepared cathodes. In particular, the Li1.05(Ni1/3Co1/3Mn1/3)O2 composition demonstrated the highest capacity retention value (∼99%) after 50 cycles and better rate performances (104, 91, 76, and 67 mAhg−1) at high current densities (229, 457, 914, and 1429 mAg−1 respectively).