Catalytic Activities of Zn-Cu Nano Ferrites on the Decomposition Kinetics of Lanthanum Oxalate hydrate (original) (raw)
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Research Paper, 2016
Nanostructured zinc−copper mixed ferrite was synthesized using sol−gel method. Different compositions of ferrite, Zn (1−x) Cu x Fe 2 O 4 (x=0.0, 0.25, 0.50, 0.75), characterized by XRD, reveal single phase inverse spinel in all the samples. With increasing copper content, the crystallite size increases. The surface morphology of all the samples, studied by SEM, shows porous structure of particles. The prepared samples were also analyzed by FT-IR and TEM. Catalytic activity of the samples was studied on lanthanum oxalate decomposition by thermogravimety .The rate constant k has the highest value with x=0.75 and 5% (mole fraction) of the catalyst and is attributed to high copper content, the mixed sites Cu 2+ −Fe + and/or Cu + −Fe 2+ ion pairs besides the one component sites Cu 2+ −Cu + , Fe 3+ −Fe 2+ , as a result of mutual charge interaction. In other words, the increasing activity of mixed oxides is attributed to increase in the content of active sites via creation of new ion pairs. With increasing Zn content, particle size increases. Variation of catalytic activity of ferrite powders is due to the changes of the valence state of catalytically active components of the ferrites, which oxidizes the carbon monoxide released from lanthanum oxalate.
An Overview of Catalytic Nature of Ferrite Nano-particles
Late uses of ferrite nanoparticles as catalyst in organic procedures are reviewed. Some applications of catalyst are incorporate with the utilization of mostly cobalt, nickel, copper, and zinc ferrites, and in addition their blended metal mixes with Cr, Cd and Mn. The ferrite nanomaterial are acquired mostly by wet-chemical sol-gel or co-precipitation strategies, all the more once in a while by the sonochemical strategy, mechanical high-energy ball processing, spark plasma sintering, microwave heating. Reactant forms with utilization of ferrite nanoparticles incorporate deterioration (specifically photocatalytic), responses of dehydrogenation, oxidation and alkylation among different procedures. Ferrite nano catalyst can be effortlessly recouped from system reactions and reused up to a few runs nearly without loss of catalytic activities. This proposed paper describe the behavior of ferrite material as a catalyst and most used methods to obtain these ferrites such copper, cobalt, Zinc and Nickel.
Journal of Chemistry
The catalytic activity of the Mn-Zn ferrites obtained by chemical methods from a solution after acid leaching of waste Zn-C and Zn-Mn batteries was studied. Precursors of metal ions (Fe, Mn, and Zn) were obtained using different precipitating agents ((NH4)2C2O4, Na2CO3, and NaOH), and then, the combustion route was used to prepare catalytically active nanocrystalline ferrites. The obtained ferrite catalysts differ in terms of microstructure, the number of acid and base sites, and the surface composition depending on the ion precursor used in the combustion process. All prepared materials were catalytically active in the butan-1-ol conversion test. Depending on the ion precursor applied in the combustion process, a selective catalyst towards aldehyde (carbonate precursor) or ketone (hydroxide precursor) formation can be obtained. Furthermore, the catalyst prepared from the hydroxide precursor exhibits the highest catalytic activity in the n-butanol test (nearly 100% conversion under ...
Ceramics International, 2011
Mixed alkali metal nanoferrites of the compositions M 0.5ÀX/2 Zn X Mn 0.05 Fe 2.45ÀX/2 O 4 (M = Li, Na and K), where x varies from 0!0.5 in steps of 0.1, have been prepared by solution combustion method. Powder X-ray diffraction analysis for all the samples show the formation of single phase cubic spinel structure. The lattice parameter increases linearly with Zn content, which is attributed to ionic size differences of the cations involved. Both X-ray as well as experimental densities show upward trend with increasing 'x' due to increase in the molecular weight of the ferrite composition. Mössbauer spectra display the superimposition of paramagnetic doublet over ferrimagnetic sextet with increasing diamagnetic 'Zn' content. The key magnetic properties of the ferrite obtained, such as saturation magnetization and Curie temperature have also been studied. The combustion method used for the synthesis is a rapid approach for direct conversion of the stoichiometric reactant solutions into fine nanoparticles of ferrite product at a temperature (600 8C) much lower than that of the conventional ceramic method. Scanning electron micrographs confirm the formation of nanosized ferrites. #
Polyhedron
Nanocrystalline powders of chromium substituted zinc ferrites with the general formula ZnFe2-xCrxO4 (0⩽x⩽2) were obtained by the sol-gel auto-combustion method, using tartaric acid as a combustion-complexing agent. The solid phase chemical reactions were monitored using infrared spectroscopy, finally indicating the absence of organic phases. The XRD results confirmed the spinel mono-phase formation in the 24-36 nm crystallite size range. Nanosized particle formation was confirmed through scanning electron microscopy. The cation distribution in the samples was estimated theoretically and the results showed that all the compounds had a mixed ionic distribution. The magnetic properties of the samples were studied using a vibrating sample magnetometer and showed that the increase in Cr3+ concentration in the Zn ferrite caused a reduction in the hysteresis losses and a non-linear reduction in the saturation magnetization. The electrical analysis showed very low values of dielectric loss ...
Industrial & Engineering Chemistry Research, 2012
Manganese−zinc ferrites were obtained through combined coprecipitation and sol−gel autocombustion methods. The effect of the precursor used in the sol−gel autocombustion synthesis on the ferrite's structural and catalytic properties was examined. The ferrite powders were characterized by XRD, BET, SEM, TG/DTA, and TPR-H 2 , and their acidic−basic properties were determined using cyclohexanol and the TPD-NH 3 test. The ferrite powder obtained from the hydroxide precursor (SC1-OH) has a larger specific surface area (16.41 m 2 /g), a larger crystallite size (35.6 nm), and a more heterogonous structure, which make it a more active catalyst. This is also achieved because of the existence of both acidic and basic centers on its surface. The ferrite obtained from the oxalate precursor (SC2-C2O4) has smaller (29.6 nm) but more aggregated particles. As a catalyst, it is more selective to dehydrogenation, which is related to its higher reducibility. The SC2-C2O4 sample also exhibits higher selectivity to ketone, and it is a much more efficient catalyst at higher temperatures.
Formation of zinc ferrite by solid-state reaction and its characterization by XRD and XPS
Journal of Materials Science, 2001
A dry mixture of ZnO and a-Fe2O3was annealed at 1200°C; the progress of the formation of the ferrite was monitored by XRD and XPS analyses at different time intervals. The presence of octahedral zinc cation was observed along with the regular tetrahedral Zn in the sample that had undergone 30 minute heat treatment. After three hours of heating, pure normal
Synthesis of Zinc Ferrite Using Ceramic Method
2017
Zinc ferrite is a compound commonly used in the electronic industries and also present in some kinds of dusts generated in steelmaking plants. The present work deals with the kinetics of the zinc ferrite synthesis, occurring through a solid-solid reaction in a selected range of temperatures, using as reactant an equimolar mixture of pure iron oxideFe2O3 and pure zinc oxide ZnO. This equimolar mixture was thermally characterized using the DTA and TGA techniques. In sequence the zinc ferrite produced were examined using X-Ray Diffraction, Scanning and Transmission Electronic Microscopy. Finally the software Topas 2.1, Difrac Plus, using the Rietveld XRD method was applied to calculate the amount of zinc ferrite generated during the synthesis reaction. The main aiming of this project was analyze the zinc ferrite generated in laboratory in the conditions of the Electric Arc Furnace dusts formation, in the temperature range from 873 to 1273 K, aiming at future zinc recycling.
Role of mode of heating on the synthesis of nanocrystalline zinc ferrite
In the present work, microwave-assisted copre-cipitation route was used for synthesis of nanocrystalline zinc ferrite and results were compared with conventionally pre-pared zinc ferrite. Synthesis conditions were kept uniform in both cases, except that the mode of heating was changed. The effects of mode of heating on the material properties were studied systematically. Microstructures of both samples were studied by scanning electron microscopy and transmission electron microscopy and the particle size was found to be in the range of 3–4 nm. Particle size distribution in microwave-processed MS-ZnFe2O4 is found to be highly uniform com-pared to conventionally processed samples (CS-ZnFe2O4). XRD data confirmed the presence of single-phase face-cen-tered cubic structure for both the samples. The XRD data fitted well with Reitveld refinement. The functional groups were analyzed by FT-IR. Local distortions in the structures were studied by FT-Raman spectra of zinc ferrites at room temperature. This study concludes that the microwave-assisted synthesis route reduced the time of reaction by around 23 h and developed uniformly distributed fine-scaled particles. This method has high potential to synthesize other ferrite materials also.
Journal of Thermal Analysis and Calorimetry, 2013
Mn-Zn ferrites were obtained by the sol-gel autocombustion methods. The effect of the precursor used in the sol-gel autocombustion synthesis on the ferrite's microstructure was examined. The as-obtained powders were characterized by XRD, FTIR, SEM, and TG/DTA. All ferrite powders obtained from different organic precursors, after gel autocombustion, were pure spinel phase, without secondary phases. The average crystallite size, estimated from Scherrer equation, was the smallest for ferrite obtained from a mixture of fuels/precursors (citric acid and EDTA). This ferrite powder has sponge-like microstructure with large pores, but it is less agglomerated than the material obtained from glycine as the fuel.