Solution Combustion Process Research Articles

Hydrogen Production from Methane Decomposition Using Nano Metal Oxides

Nanotechnology is like an umbrella, under this maximum all the fields, branches are developing, like a green-house effect for plant. Nanotechnology can provide new concepts for the energy department which can utilise and provide new sources for all energy challenges, like generation, renewable and storage with less energy consumption, that provide an economy to the development to country. This can be achieved with the help of hydrogen for energy application; thermo catalytic decomposition of methane is a simple process to produces carbon free hydrogen. Mono metallic NiO, Co3O4, ZrO2 and ZnO catalyst were synthesised by a solution combustion process. The methane decomposition and catalyst activity test is done at fixed bed reactor with a methane flow rate of 54 SCCM with an operation condition of 850°C temperature under atmospheric pressure respectively. The catalyst is characterised by BET, XRD and PSA. The complete observation and catalyst performance shows that catalyst activity is high at the initial time of reaction and decreases with deposition (time) of carbon over the catalyst. As resultant the methane decomposition showed activity nearly 3h for all the catalyst. Comparison study shows that hydrogen yield and deposited carbon occurs (catalyst activity) is completely based on particle size, Surface area and Pore volume of material used.

Synthesis Of Yttrium Ferrite (YFeO3) By Solution Combustion Synthesis Using Alanine As A Fuel

We report, synthesis of nano crystalline YFeO3 powders by solution combustion process using alanine (C3H7NO2) as a fuel at stoichiometric ratio. The yttrium-nitrate hexahydrate (Y(NO3)3.6H2O) and ferric nitrate nonahydrate (Fe(NO3)3.9H2O) were used as oxidizers. The prepared powders were characterized by X-ray diffraction (XRD) for phase analysis and scanning electron microscope (SEM) for microstructure. The experimental results confirmed the formation of phase pure crystalline yttrium ferrite by comparing the peaks of XRD pattern of the sample with the peaks of standard XRD pattern of JCPDS card number 39-1489 of YFeO3. Crystallite size of the powder was 46 nm, when calculated using Scherer formula. The SEM shows the formation of porous agglomerated particles of nanopowders.

Novel MgTiO3:Eu3+ Nanophosphor Its Photometric Analysis for Multifunctional Applications

MgTiO3:Eu3+ (1-11 mol%) nanophosphors were synthesized by a facile solution combustion process. PXRD studies confirm single phase rhombohedral structure with the space group R-3. The average crystallite size determined by TEM and Scherrer’s method was found to be in the range 20-50 nm. Effects of Eu3+ (1-11 mol%) cations on the luminescence properties of MgTiO3 nanoparticles exhibit intense red emission upon 415 nm near ultra violet (NUV) excitation. The characteristic emission peaks recorded in the range 500-700 nm may be attributed to the 4f–4f intra shell transitions (5D0→7Fj=0,1,2,3) of Eu3+ cations. The CIE chromaticity co-ordinates were calculated from emission spectra and the values (x, y) were very close to NTSC standard values for red emission. Therefore, the present phosphor may be highly useful for solid state display applications and for wLEDs.

MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performance

A series of MgO-based adsorbents were prepared through solution–combustion synthesis and ball-milling process. The prepared MgO-based powders were characterized using X-ray diffraction, scanning electron microscopy, N2 physisorption measurements, and employed as potential adsorbents for CO2 adsorption. The influence of structural and textural properties of these adsorbents over the CO2 adsorption behaviour was also investigated. The results showed that MgO-based products prepared by solution–combustion and ball-milling processes, were highly porous, fluffy, nanocrystalline structures in nature, which are unique physico-chemical properties that significantly contribute to enhance their CO2 adsorption. It was found that the MgO synthesized by solution combustion process, using a molar ratio of urea to magnesium nitrate (2:1), and treated by ball-milling during 2.5hr (MgO-BM2.5h), exhibited the maximum CO2adsorption capacity of 1.611mmol/g at 25°C and 1atm, mainly via chemisorption. The CO2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area, total pore volume, pore size distribution and crystallinity. The reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO2 adsorption–desorption times, without any significant loss of performance, that supports the potential of MgO-based adsorbent. The results confirmed that the special features of MgO prepared by solution–combustion and treated by ball-milling during 2.5hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO2 capture technologies.

Synthesis and electrochemical performance of P2-Na0.67AlxCo1-xO2 (0.0 ≤ × ≤ 0.5) nanopowders for sodium-ion capacitors

Layered P2-Na0.67Al x Co 1-x O2 (0.0 ≤ × ≤ 0.5) nanopowders were prepared by solution combustion process. These nanopowders were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and field emission scanning electron microscopy (FE-SEM) analysis. The electrochemical behaviours of the prepared layered P2-Na0.67Al x Co 1-x O2 nanopowder-based electrodes were investigated by cyclic voltammetry, electrochemical impedances and galvanostatic charge-discharge studies in 1 M Na2SO4 solution. The layered P2-Na0.67Al0.3Co0.7O2 has achieved a high specific capacitance of 260 F g−1 at a constant current density of 1 A g−1. The excellent electrochemical performance of Na0.67Al0.3Co0.7O2 is due to the partial substitution of Al3+ ions for Co3+ ions that leads to decrease in lattice parameter, resulting in the better structural stability during the Na+ ion intercalation/deintercalation reaction process. Moreover, the Na0.67Al0.3Co0.7O2 demonstrates a long cycle life with 80.1 % of its specific capacitance retention even after 5000 continuous charge-discharge process at a constant current density of 1 A g−1.

Fabrication of Magnetic NiFe2O4 Nanorods and Their Removal Performances of Congo Red.

Magnetic NiFe2O4 nanorods were prepared successfully via a facile solution combustion process, the morphology, chemical composition, microstructure and magnetic properties of as-prepared NiFe2O4 nanorods were investigated by XRD, VSM, SEM, TEM, EDX, SAED and BET techniques. The magnetic NiFe2O4 nanorods were characterized with average length of about 130 nm, the diameter of around 25 nm, the specific magnetization of 105.2 Am2/kg, and the specific surface area of 88.8 m2/g. The nanorods were employed to remove congo red (CR) from aqueous solutions, the adsorption kinetic and adsorption isotherm of CR onto NiFe2O4 nanorods at room temperature were investigated. The regression equation was found in good agreement with the pseudo-second-order kinetic model in a range of initial CR concentrations of 80-400 mg/L. Compared with Freundlich and Temkin models, Langmuir model fitted the adsorption isotherm of CR onto NiFe2O4 nanorods better, which suggested that the adsorption of CR onto NiFe2O4 nanorods was a monolayer absorbing mechanism. Meanwhile, the adsorption capacity of CR onto NiFe2O4 nanorods is large when pH is less than 9.

One-step large scale combustion synthesis mesoporous MnO2/MnCo2O4 composite as electrode material for high-performance supercapacitors

High quality MnO2/MnCo2O4 composites have been successfully synthesized by a one-step solution combustion process at 300°C for 2h in air. The effects of the amount of glycine and molar ratios of Mn/Co on phase composition, morphology and electrochemical properties of products were investigated. The prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and Brunauer-Emmett-Teller methods. Based on the optimum fuel/oxidizer molar ratios, the products transformed from spinel MnCo2O4 granular aggregates to a mixture of MnO2/MnCo2O4 composites with increase the molar ratios of Mn/Co. The electrochemistry performance of prepared different specimens were evaluated and compared through cyclic voltammetry and charge-discharge anylysis in 2.0M KOH electrolytic solution. Electrochemical measurements showed that the MnO2/MnCo2O4 exhibited a optimal electrochemistry performance with the Mn:Co:glycine molar ratio of 3:4:31.5/9. The maximum specific capacitance of 497F/g is achieved at a current density of 0.5A/g (or 312F/g at 10A/g). The high electrochemical performance would be attributed to the numerous nanopores, large specific surface and synergistic effects of the MnO2 and spinel MnCo2O4.

Improvement in photoluminescence properties of (Y,Gd)(V1−x P x )O4:Eu3+ phosphors by doping Al3+

(Y0.5Gd0.5)0.94−y (V1−x P x )Al y O4:0.06Eu3+ (0 ≤ x ≤ 1.0 and 0 ≤ y ≤ 0.02) phosphors are synthesized by the solution combustion process. In this study, structural and photoluminescence properties of the (Y0.5Gd0.5)0.94−y (V1−x P x )AlyO4:0.06Eu3+ phosphors are reported. The emission characteristics of the (Y0.5Gd0.5)0.94VO4:0.06Eu3+ phosphor under vacuum ultraviolet (VUV) excitation are greatly improved with the incorporation of Al3+ ions and partial substitution of P5+ for V5+. The red emission intensity of the (Y0.5Gd0.5)0.925(V0.25P0.75)Al0.015O4:0.06Eu3+ phosphor is 151% stronger than that of the (Y0.5Gd0.5)0.94(V0.25P0.75)O4:0.06Eu3+ phosphor.

Removal of Methyl Blue by Magnetic CuFe<SUB>2</SUB>O<SUB>4</SUB> Nanoparticles Prepared via the Novel Solution Combustion Process

Removal of Methyl Blue by Magnetic CuFe<SUB>2</SUB>O<SUB>4</SUB> Nanoparticles Prepared via the Novel Solution Combustion Process

Effects of Fuel to Synthesis of CaTiO3 by Solution Combustion Synthesis for High-Level Nuclear Waste Ceramics.

A solution combustion process for the synthesis of perovskite (CaTiO3) powders is described. Perovskite is one of the crystalline host matrics for the disposal of high-level radioactive wastes (HLW) because it immobilizes Sr and Lns elements by forming solid solutions. Solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between nitrate and organic fuel, the exothermic reaction, and the heat evolved convert the precursors into their corresponding oxide products above 1100 degrees C in air. To investigate the effects of amino acid on the combustion reaction, various types of fuels were used; a glycine, amine and carboxylic ligand mixture. Sr, La and Gd-nitrate with equivalent amounts of up to 20% of CaTiO3 were mixed with Ca and Ti nitrate and amino acid. X-ray diffraction analysis, SEM and TEM were conducted to confirm the formed phases and morphologies. While powders with an uncontrolled shape are obtained through a general oxide-route process, Ca(Sr, Lns)TiO3 powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using this method.

Structural and photoluminescence investigations of Sm3+ doped BaY2ZnO5 nanophosphors

BaY2ZnO5:Sm3+ nanophosphor was successfully synthesized using solution combustion process. XRD and photoluminescence (PL) techniques were used to analyze the structural and photoluminescence properties. Morphological study of the thermally stable powder was carried out using transmission electron microscope (TEM). Rietveld refinement technique has been used to analyze the samples qualitatively as well as quantitatively. X-Ray diffraction analysis confirms that the highly crystalline single phased Sm3+ doped BaY2ZnO5 nanophosphor crystallizes in orthorhombic lattice with Pbnm space group. The average particle size lies in the range 80–90nm with spherical morphology. The photoluminescence excitation at 411nm yields an intense orange–red emission centered at 610nm due to 4G5/2–6H7/2 transition. The concentration dependent luminescent behavior of BaY2(1−x)Sm2xZnO5 nanophosphor shows that the optimum concentration for best luminescence is 3mol%. These results indicate that these nanophosphors find potential applications in the field of phosphor-converted white LED systems.

Synthesis, microstructure and magnetic properties of nanocrystalline MgFe2O4 particles: Effect of mixture of fuels and sintering temperature

The present article reports the results of studies related to the synthesis of MgFe2O4 nanocomposite powder by solution combustion process using mixture of fuels containing urea (U) and ammonium acetate (AA). The effect of mixture of fuel and sintering temperature on phase formation, structural, morphological and magnetic properties of MgFe2O4 particles were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive absorption x-ray (EDAX) and vibrating sample magnetometer (VSM). Thermodynamic modeling of the combustion reaction shows that by using a mixture of urea and ammonium acetate fuels, the adiabatic flame temperature (Tad), exothermicity and amount of gases produced during the combustion process as well as product characteristics could be controlled. The use of mixture of fuels (U and AA) in the synthesis of MgFe2O4 was found to produce ferrites with finer agglomerates, higher crystallinity, higher magnetic properties and smaller crystallite sizes than when only urea was used. It was found that only samples prepared with a mixture of fuels (0.5U + 0.5AA) and sintered at 900oC for 2 h produced pure ferrite spinel phase while the auto-combusted and powders sintered at 600oC for 2 h had secondary phases. Apart from giving detailed information about the structural order of the samples, Raman spectroscopy also confirmed that MgFe2O4 is a mixed spinel ferrite.

Immobilization and Characterization of Penicillin G Acylase (PGA) Immobilized on Magnetic Ni₀.₅Zn₀.₅Fe₂O₄ Nanoparticles.

Magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles were prepared via the solution combustion process and their microstructure and magnetic properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The as-prepared magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles are characterized with average grain size of about 20 nm and magnetization of 90.3 Am²/kg. The surface of magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles was modified by use of sodium silicate and N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, and the penicillin G acylase (PGA) was successfully immobilized on the surface-modified magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles. The results show that the activity for the immobilized PGA is affected less by pH and temperature than that for the free PGA, and the immobilized PGA exhibits a high effective activity, good stability of enzyme catalyst. This immobilized PGA on magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles can be separated from the solution by the external magnetic field for cyclic utilization, and they could retain about 70% of initial enzyme activity after 11 consecutive operations. The kinetic parameters (Km and Vmax) were determined, and the value of Km for the immobilized PGA (204.53 mmol/L) is higher than that of the free enzyme (3.50 mmol/L), while Vmax (1.93 mmol/min) is also larger than that of the free enzyme (0.838 mmol/min).

EPR and optical properties of green emitting Mn-doped BaMgAl10O17 nano-phosphors prepared by a combustion reaction

Manganese doped BaMgAl10O17 nano-phosphors were synthesized by a low-temperature initiated, gas producing solution combustion process. Phase purity of the prepared phosphors was determined using X-ray diffraction technique. Dynamic light scattering technique was used to estimate the average particle size of the synthesized products. Scanning electron microscopy technique was used to study the morphology of the prepared samples. Fourier transform infrared spectroscopy was used to ascertain the formation of the aluminate host. UV–visible absorption spectroscopy showed band maxima at around 260 nm and intense band maxima at around 216 nm. Electron paramagnetic resonance experiments for the system were carried out to understand the site occupancy of the Mn ions. The photoluminescence excitation and emission spectra suggested the stabilisation of Mn ions in Td geometry. From the colour characterisation of the system it was found out that the system can be effective as a green phosphor material with wide range of applications.

Effect of Pd deposition procedure on activity of Pd/Ce0.5Sn0.5O2 catalysts for low-temperature CO oxidation

Two methods for the preparation of Pd/Ce0.5Sn0.5O2 catalysts have been used: solution combustion (SC) of Pd, Ce and Sn precursor mixtures, and incipient wetness impregnation by [Pd(NO3)2(H2O)2] solution of Ce0.5Sn0.5O2–δ support, obtained by the SC technique (SC+IWI). The formation of metallic palladium was observed in addition to ionic palladium in a Pdx(Ce0.5Sn0.5)1–xO2–x–δ solid solution due to high-temperature Pd precursor decomposition during the SC process. IWI of Ce0.5Sn0.5O2–δ support has been demonstrated to lead to a uniform solid solution of Pd2+ ions in the Ce0.5Sn0.5O2–δ matrix at 1% Pd content that resulted in high catalyst activity towards CO oxidation. The increase of Pd content to 5% showed no influence on catalytic activity. This observation is explained by the formation of low active PdO species when Pd content is more than 1%. The proposed SC+IWI method allows obtaining highly active Pd/Ce0.5Sn0.5O2 catalysts with low palladium content.

Facile and Rapid Synthesis of ZnO Nanoparticles for Photovoltaic Device Application.

Well-crystalline ZnO nanoparticles were prepared through simple, facile and rapid solution combustion process and utilized as photoanode material for the fabrication of dye-sensitized solar cell. The detailed characterizations of the ZnO nanoparticles revealed that the crystalline product with wurtzite hexagonal phase was grown in high-density. The chemical composition analyzed through FTIR and EDS confirmed the purity of the ZnO nanoparticles. UV-vis and Raman spectral studies were applied for studying the optical and vibrational properties of as prepared ZnO nanoparticles, respectively. The fabricated dye-sensitized solar cell exhibited overall photo-to-electricity conversion efficiency (η) of 0.94%, open-circuit current (V(oc)) of 0.531 V, short circuit current (J(sc)) of 4.11 mA/cm2 and fill factor (FF) of 0.43.

Novel AgBr/Ag3PO4 Decorated Ceria Nanoflake Composites for Enhanced Photocatalytic Activity toward Dyes and Bacteria under Visible Light

The aim of this study was to develop heterogeneous visible light active photocatalysts using AgBr and Ag3PO4 using CeO2 nanoflakes as an efficient substrate. Ascorbic acid was employed as a fuel to synthesize fine ceria nanoflakes by a facile solution combustion process. AgBr and Ag3PO4 were decorated on ceria to prepare AgBr/Ag3PO4/ceria nanocomposites. The structure of the composite was determined by X-ray diffraction analysis. Novel flakelike morphology was revealed using electron microscopy techniques. The nanocomposites exhibit excellent photocatalytic activity under visible light compared to pristine ceria nanoparticles. The nanocomposite catalyst particles degraded both anionic and cationic dyes. It also exhibited efficient antimicrobial activity under visible light. The AgBr/Ag3PO4/ceria nanocomposite was characterized using X-ray diffraction analysis, diffuse reflectance spectroscopy, electron microscopy, BET surface area analysis, and X-ray photoelectron spectroscopy, and the reasons for enhance...

Effect of Process Parameters on the Characteristics of Nanocrystalline Alumina Particles Synthesized by Solution Combustion Process

Nanocrystalline ceramic oxide particles with high purity can be synthesized efficiently by the solution combustion synthesis route, which is based on redox reactions between metal salts and reducing agents such as urea and glycine. In the present study, nanocrystalline alumina powders were synthesized using aluminium nitrate nonahydrate as the metal salt and urea as the fuel. The powders were characterized primarily for the phases present and crystallite size (from X-ray diffractometry) and morphology (by scanning electron microscopy). When stoichiometric amounts of the starting chemicals were taken, X-ray diffraction (XRD) analysis of the synthesized powder revealed it to be phase-pure α-Al2O3, with a crystallite size of 42 nm. Electron microscopy of the synthesized powder revealed a flaky morphology. Further, the pH value of the solution containing the stoichiometric amounts of the aluminium salt and the fuel was systematically varied by dissolving in liquid ammonia. It was observed (from XRD analysis) that an increase in the pH progressively stabilized the metastable γ-Al2O3 phase. An increase in the fuel (urea) content had no effect on the phase stability, but decreased the crystallite size of α-Al2O3. A crystallite size of 29 nm could be achieved with an excess fuel ratio of 1.5 over the stoichiometric value.

A Novel Process for the Preparation of Ni<SUB>0.5</SUB>Zn<SUB>0.5</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> Nanoparticles and Their Removal Behaviors of RR-2BF

A novel solution combustion and calcination process has been reported for the preparation of magnetic Ni0.5Zn0.5Fe2O4 nanoparticles. The morphology, chemical composition, microstructure and magnetic properties of as-prepared Ni0.5Zn0.5Fe2O4 nanoparticles were investigated by XRD, TEM, SAED and VSM. The magnetic Ni0.5Zn0.5Fe2O4 nanoparticles were characterized with average grain size of about 18 nm and specific magnetization of 90.4 Am2/kg. The nanoparticles were employed to remove reactive red 2BF (RR-2BF) from aqueous solutions; and the adsorption kinetics and the adsorption isotherms were investigated by UV spectroscopy at room temperature; the regression equation was found in good agreement with the pseudo-second-order kinetic model in a range of initial concentration of 50-200 mg/L. Compared with Freundlich and Temkin models, Langmuir model fits the adsorption isotherm of RR-2BF onto the magnetic Ni0.5Zn0.5Fe2O4 nanoparticles better, which suggested that the adsorption of RR-2BF onto the magnetic Ni0.5Zn0.5Fe2O4 nanoparticles was monolayer, and the adsorption energy was constant.

Facile and low-cost combustion-synthesized amorphous mesoporous NiO/carbon as high mass-loading pseudocapacitor materials

Amorphous and mesoporous NiO/carbon composite is prepared by a one-step and cost-efficient solution combustion process at only 250 °C within 30 min in air. The effects of fuel dosages on phase composition, morphology and electrochemical capacitive behaviors of products are investigated. Experimental results demonstrate that the optimized amorphous NiO/carbon composite shows a high specific capacitance of 1272 F/g (or an areal capacitance of 1.82 F/cm2) at 1 A/g, along with an excellent rate performance (642.5 F/g at 10 A/g) under a mass loading of 1.43 mg/cm2. With even a high mass loading of 9.38 mg/cm2, the specific capacitance of this composite still remains a high volume of 588.5 F/g (or an areal capacitance of 5.52 F/cm2). Meanwhile, the electrode retains 77% of its initial capacitance after 2000 cycles at a high current density of 10 A/g. The effects of crystalline degree on the electrochemical performance have also been investigated by annealing samples in air or N2 atmospheres. The 2 h annealed sample in N2 atmosphere shows a specific capacitance up to 1527 F/g, due to the improvement of carbonization. Current study suggests that this combustion process has promise in mass production of well-performance electrode materials for supercapacitors.