Effect Of Preparation Route Research Articles

Effect of preparation routes on the performance of a multi-component AB2-type hydrogen storage alloy

This article presents experimental results on the preparation and characterisation of a multi-component AB2–type intermetallic hydrogen storage alloy (A = Ti0.85Zr0.15, B = Mn1.22Ni0.22Cr0.2V0.3Fe0.06). The alloy samples were prepared by induction melting using Y2O3-lined alumo-silica and graphite crucibles. The characterisation results were compared with the ones for the reference sample of the same composition prepared by arc melting. It has been shown that the induction-melted samples exhibit reduced hydrogen sorption capacities and sloping plateaux on the pressure composition isotherms (PCI’s). The origin of the observed effects has been shown to be in the inhomogeneity of the induction-melted alloys and their contamination due to crucible—melt interaction, particularly pronounced for the alloy melted in the alumo-silica crucible; this alloy was additionally characterised by the decrease of Zr/Ti ratio and, in turn, higher plateau pressures of the PCI’s.

Nickel phase deposition on V2CTx/V2AlC as catalyst precursors for a dry methane reforming: The effect of the deposition method on the morphology and catalytic activity

Dry reforming of methane (DRM) is a promising alternative technology for the production of syngas with simultaneous utilization of two main greenhouse gases (CH4, CO2). However, DRM technology is still an industrially immature process due to the lack of stable and active catalyst. Therefore, the search for new catalytic materials is of great research interest. Recently, MAX and MXenes materials are increasingly being tested as potential materials for catalytic processes including dry reforming of hydrocarbons. However, transition metal carbides may be deactivated under DRM conditions due to phase transition caused by an oxidation process. The combining of the MAX/MXene materials with nickel phase may be beneficial for to improve catalytic activity and stability. In this view, we report preparation and characterization of nickel-modified V2CTx/V2AlC materials. The Ni–V2CTx/V2AlC catalysts were prepared using HF-etching followed by impregnation/precipitation method. The effect of preparation route on morphology and catalytic activity was investigated. The properties of fresh and spent catalysts were evaluated using XRD, XPS, MP-AES, SEM, BET surface area, H2-TPR, CO2-TPD, TG/DTG and TEM techniques. Catalytic activity was investigated in the DRM process at 800 °C and 1 bar. It was found that the V2CTx/V2AlC- based materials undergo phase transition to vanadium oxide V2O3, vanadium carbide V8C7 and aluminium oxide. The presence of nickel was crucial for the catalyst activity of V2CTx/V2AlC- based catalysis. The catalytic activity was different and related to the preparation procedure resulting in dissimilar nickel-phase morphology and intercalation of sodium ions. It was found that the distribution of nickel phase and presence of alkali ions determined catalysts’ activity and stability. The highest activity and stability in DRM process was observed for Ni–V2CTx/V2AlC_IMP catalysts obtained using only impregnation method without precipitation agents. For the catalysts nickel phase was distributed uniformly forming needle-like structures. The CO2 and CH4 conversions during 20 h-test were in the range of 90–93% and 90-80%, respectively. The molar ration of H2 to CO in outlet stream fluctuated from 1.05 in the first hour of the process to 0.95 after 20 h of the DRM. The activity and stability of Ni–V2CTx/V2AlC_IMP catalyst was higher compared to unmodified V2CTx/V2AlC, unetched V2AlC and Ni–SiO2.

Synthesis and characterization of MgO nanostructures: A comparative study on the effect of preparation route

In this study, MgO nanostructures were synthesized by five facile and diverse chemical synthesis routes, viz. precipitation (PT), sonication-precipitation (SPT), microwave combustion (MWC), conventional combustion (CC), and solvothermal (ST) processes. The influence of aforementioned synthesis routes on crystallinity, crystallite size, morphology, optical, and surface traits of MgO nanostructures was evaluated by XRD, BET, FESEM, FETEM, optical absorption, steady-state and time-resolved photoluminescence analyses. Furthermore, antioxidant and antibacterial properties of MgO nanostructures were examined. XRD analysis revealed that crystallite size and relative crystallinity (%) of MgO varied from 9 to 42 nm and 90.70–99.06%, respectively, depending on the synthesis route followed. The application of microwave irradiation (MWC) and sonication (ST) reduced particle size and increased specific surface area of MgO nanostructures compared to nanostructures obtained via CC and PT methods. This could be due to faster reaction kinetics in MWC and small-scale turbulence generated during sonication that restricts growth and agglomeration of nuclei during nanostructure synthesis. FESEM analysis revealed flake, sphere, natural rose, and marigold flower-like morphologies of MgO due to different methods followed, that can be attributed to the differences in nanostructure formation mechanism involved. The highest photoluminescence intensity observed with MgO synthesized via MWC is likely to produce a maximum number of reactive oxygen species. Consequently, MgO synthesized through MWC process showed highest bactericidal and antioxidant activities compared to MgO synthesized via other routes. Thus, present study demonstrated that properties of nanostructures required for a particular application could be customized by proper choice of the synthesis route.

Methylene blue removal from aqueous solution using micro-/mesoporous solid-state adsorbents: effect of preparation route

Methylene blue removal from aqueous solution using micro-/mesoporous solid-state adsorbents: effect of preparation route

Performance of Ni/Al2O3-MgO catalyst for Dry Reforming of Methane: Effect of preparation routes

Nickel based nano-catalysts, supported on bimetallic oxide support (i.e. Ni/Al2O3-MgO) were prepared by the co-precipitation (one step, Catalyst-A) and co-precipitation followed by impregnation (two steps, Catalyst-B) techniques separately. The catalysts were then tested for the dry reforming of methane (DRM) reaction. The effect of catalyst synthesis technique on their performance has been analysed. The Ni/Al2O3-MgO nano-catalyst prepared by co-precipitation followed by impregnation method (two steps) technique was found to be superior to the one synthesized by co-precipitation (one step) method. The elevated CO2 and CH4 conversions and stable H2/CO ratio have been observed throughout the DRM reaction at atmospheric pressure (i.e., 1atm), 800°C for Catalyst-B. Catalyst-B was better in terms of activity, conversion to syngas, stability, and reduced coke formation comparatively.

Effect of preparation route on Sr2TiO4 catalyst for the oxidative coupling of methane

Four different preparation routes were used to synthesize Sr2TiO4 with the structure of layered perovskite: sol-precipitation (SP), co-precipitation (CO), citrate precursor (CT) and mechanochemical (MA) methods with further calcinations at 1100 °C. The XDR, XPS, BET, SEM techniques showed that the different preparation routes caused the formation of layered perovskite phase with different admixture phases, particle sizes and the surface enrichment with layered perovskite (for SP and MA samples) or strontium oxide (for CO and CT samples). The trend of increasing of CH4 conversion and C2-yield in oxidative coupling of methane at 800-900 °C was found to be the following: SP≈MA > CO > CT samples. The C2-yield of the most active catalysts was measured to be about 12%.

Synthesis and characterization of sintered hydroxyapatite: a comparative study on the effect of preparation route

Hydroxyapatite (HAp) is prepared synthetically by three different routes—wet chemical coprecipitation, sol–gel, and solution combustion routes. Different characterizations of the powders obtained from different routes were done for comparative analysis. The as-prepared powders were calcined between 600 and 1300 °C and studied for phase stability using X-ray diffraction (XRD). The thermal analysis and Fourier transform infrared (FTIR) spectroscopy analysis were also studied. The calcined powders were observed for microstructural changes at different temperatures using field emission scanning electron microscope (FESEM). The powders were then pressed to form pellets for analyzing the different sintering behavior such as dilatometry, bulk density, and apparent porosity. The sintered pellets were also examined under FESEM. It was observed that the HAp obtained from coprecipitation route (HCop) achieved the highest bulk density as well as hardest among all. Bioactivity test was also done for HCop samples for 7, 14, 21, and 28 days and observed under FESEM.

Enhancement in Magnetic Properties of Mg-Doped Strontium-Substituted Bismuth Ferrite Prepared by Solid-State and Sol-Gel Methods

We report a potential way to effectively improve the magnetic properties of BiSrFeO3 (BSFO) through Mg 2+ ion substitution at the Fe sites of BFO lattice. Polycrystalline Bi0.95Sr0.05Fe0.98Mg0.02 O 3 (BSFMO) powder was prepared through optimized solid-state (SS) and sol-gel (SG) reaction methods. The effect of preparation routes on the crystal purity and multiferroic properties of the BSFMO was investigated. The purity and structural changes induced by Mg doping are confirmed by X-ray powder diffractometer and IR spectra. Enhanced magnetic properties are observed in Mg-substituted samples, which simultaneously exhibit ferromagnetic and superparamagnetic properties at room temperature. The improved magnetic properties and soft nature obtained by Mg doping in BSFO particles demonstrate the possibility of BFO particles to practical applications.

Synthesis and characterization of sintered beta-tricalcium phosphate: A comparative study on the effect of preparation route

Beta-tricalcium phosphate (β-TCP) was prepared by three different routes namely, wet chemical coprecipitation, sol-gel and solution combustion synthesis. The synthesized powders were calcined at different temperatures and characterized for phase evolution study, thermal analysis, Fourier transform infrared (FTIR) spectroscopy, microstructural study for comparative analysis. The optimal thermal treatment required to prepare pure β-TCP powders was determined and after calcination of the synthesize powders prepared by different routes, pure β-TCP was obtained. The sintering temperature required to prepare fully dense β-TCP completely free from α-form was identified. The powders were then used to make dense and compact bodies sintered at 1200 and 1250°C. The sintering behaviour of the dense bodies was analysed using dilatometry, densification and microstructural study. It was found that the pellet prepared from powder synthesized via co-precipitation route attained maximum density compared to the pellets prepared from powders synthesized via sol-gel and solution combustion route.

Investigations of thermoluminescence properties of multicrystalline LiF: Mg, Cu, Si phosphor prepared by edge defined film fed growth technique

Thermoluminescence (TL) properties of LiF: Mg, Cu, Si phosphor prepared in multicrystalline form using edge defined film fed growth (EFG) technique has been investigated. The effect of preparation route on TL properties and thermal stability has been studied. To improve the TL dosimetry properties, phosphor is subjected to different annealing temperatures ranging from 250 °C to 450 °C. The shape of the glow curve structure and peak temperature remains similar at different annealing temperatures, however peak intensities vary. The consistency in the glow curve structure with annealing temperature elucidate that TL trapping states are stable in nature. Thermal annealing at 300 °C for 10 min gives maximum TL intensity with main dosimetry peak at 209 °C. The TL intensity of the main dosimetry peak is increased by a factor of five as compared to as-grown crystal. The thermal stability of LiF: Mg, Cu, Si is found to be better than LiF: Mg, Cu, P. Trapping parameters are calculated to have an insight study of defect states. A simple glow curve structure, tissue equivalency, thermal stability, low residual signal, linear response and reusability makes LiF: Mg, Cu, Si a suitable phosphor for radiation therapy, radio diagnostics and personnel dosimetry applications.

Effect of synthesis route on the multiferroic properties of BiFeO3: A comparative study between solid state and sol–gel methods

Polycrystalline BiFeO3 (BFO) powder was prepared through optimized solid state (SS) and sol–gel (SG) reaction methods. The effect of preparation routes on the crystal purity and multiferroic properties of the BFO was investigated. Sol–gel synthesis results almost a single-phase material at relatively lower temperatures while the solid-state method results into BFO with a small amount of Bi2Fe4O9 secondary phase. The grain size of SG processed sample reduces to half the size of the one that is prepared by SS. Elemental analysis shows a stoichiometric Bi:Fe content for SG samples by restricting the Bi loss. In comparison with the SS samples, dielectric constant of SG samples exhibit higher values with Maxwell–Wagner type dielectric dispersion. A cusp at 50 K was seen in M–T curves for SS samples, for which no frequency dependence was observed in a.c susceptibility measurements ruling out the earlier predictions of spin glass nature in this system. M−H loops show a typical antiferromagnetic nature at 300 K while a weak ferromagnetic behavior is found at 10 K. A slight increase in HC and Mr was observed for SG samples over SS. The improved properties of SG processed BFO makes it more promising for applications.

Effect of preparation routes on activity of Ag-MnOx/C as electrocatalysts for oxygen reduction reaction in alkaline media

The effect of preparation routes on the physical characteristics and activity of the Ag-MnOx/C composites toward the oxygen reduction reaction (ORR) in alkaline media were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersion spectroscopy (EDS) as well as scanning electron microscopy (SEM) and electrochemical techniques. The results show that more Ag and Mn species present on the surface of the Ag-MnOx/C composite prepared by two-step route (Ag-MnOx/C-2) compared to the one prepared by one-step route (Ag-MnOx/C-1), which contributes to its superior activity toward the ORR. The higher electron transfer number involved in the ORR can be observed on the Ag-MnOx/C-2 composite and its specific mass kinetic current at −0.6 V (vs Hg/HgO) is 46 mA/μg, which is 23 times that on the Ag/C. The peak power density of zinc–air battery with the Ag-MnOx/C-2 air electrode reaches up to 117 mW/cm2.

Effect of preparation route on the microstructure and electrical conductivity of co-doped ceria

Abstract Dense Ce 0.8 Sm 0.1 Gd 0.1 O 2− δ electrolytes were fabricated by sintering of CeO 2 solid solutions which were prepared from metal nitrates and NaOH using self propagating room temperature synthesis (SPRT). Three different routes were employed to obtain CeO 2 solid solution powders: (I) hand mixing of reactants, (II) ball milling of reactants and (III) ball milling of Ce 0.8 Sm 0.2 O 2− δ and Ce 0.8 Gd 0.2 O 2− δ solid solutions previously prepared by ball milling of corresponding nitrates and NaOH. Density measurements showed that ball milling, which is more convenient than hand mixing, is an effective way to obtain almost full dense samples after presureless sintering at 1550 °C for 1 h. These samples had larger grain size and consequently higher conductivity than the samples obtained by hand mixing. The highest conductivity of 2.704×10 −2 (Ω cm) −1 was measured at 700 °C in a sample prepared by route II. It was found that reduced grain size in samples obtained by hand mixing leads to a decrease in grain boundary conductivity and therefore decrease in the total conductivity. The results showed that mixing of single doped ceria solid solutions improved densification and inhibited grain growth.

Structure and Catalytic Properties of Pd/10Al2O3·2B2O3. Effect of Preparation Routes and Additives

Abstract The synthesis route of 10Al2O3·2B2O3 (10A2B) and effect of additives were studied to use this compound as a thermally stable support material for Pd catalysts. The preparation by reverse coprecipitation was found to have a beneficial effect on the BET surface area of 10A2B and thus Pd metal dispersion, compared to other preparation routes via solid-state reaction and hydrolysis of metal alkoxides. The addition of 3 wt % BaO suppressed the sintering of 10A2B and Pd during thermal aging at 900 °C in a stream of air containing 10% H2O. Although direct interactions between Pd and the support material were not detected by EXAFS, the catalytic performance for NO–CO–C3H6–O2–H2O reactions under modulated air-to-fuel ratio (A/F) conditions was strongly influenced by the Ba additive. The activity for NO and C3H6 in a rich region (A/F < 14.6) was especially enhanced in the presence of Ba because of accelerated elemental reactions including NO–CO and NO–C3H6. In situ FT-IR of CO suggested that the Pd electronic state changed by electrostatic effect of Ba additives would activate NO and weaken the self-poisoning effect of C3H6.

Effect of preparation route on the properties of slip-casted Al2O3/YAG composites

Alumina composites containing 5, 10 and 20vol.% YAG were produced by a slip-casting process. Two different routes for adding the YAG phase were chosen. Either by mixing of alumina with previously produced YAG powder or by coating of an adequate amount of yttria to form YAG precipitates during the calcining step. The mechanical properties of the sintered samples were measured and compared. Independent from the preparation route Al2O3/10vol.% YAG composites showed best mechanical properties. Significant differences in the densification behavior appeared between the two different manufacturing technologies. The presence of intermediately formed phases like YAM and YAP during the powder preparation step of coated composites is probably the reason why mixed composites showed higher mechanical properties than coated composites.

Effect of preparation route on the degradation behavior and ion releasability of siloxane-poly(lactic acid)-vaterite hybrid nonwoven fabrics for guided bone regeneration

Two types of nonwoven fabric, consisting of siloxane-doped vaterite (SiV) and poly(lactic acid) (PLA), for guided bone regeneration (GBR) were prepared by an electrospinning. One of the fabrics, SiV-PLA(M), was derived from PLA mixed with the solution of SiV dispersed in chloroform. Another one, SiV-PLA(K), was derived from a composite prepared by kneading SiV and PLA while heating at 200°C. The SiV-PLA(K) fabric shows higher degradability in dilute NaOH aq. than the SiV-PLA(M) fabric. To improve the cellular compatibility of the fabric, the fibers were coated with hydroxyapatite (HA) by soaking in simulated body fluid. The HA-coated SiV-PLA(K) fabric showed the release of silicate ions; the amount was reduced by 1/5 to 1/8 compared with that of the HA-coated SiV-PLA(M) fabric, and the excessive release was controlled. The preparation route of kneading at 200°C led to formation of a fabric with degradation behavior and ion releasability effective for bone regeneration.

Effect of preparation routes on the catalytic activity over SmFeO 3 oxide

The perovskite-type SmFeO 3 powders were prepared by the four different methods, named decomposition method of heteronuclear cyano complexes (CN), polymer precursor method (PP), reverse micelle method (RM) and reverse homogenous precipitation method (RHP), and their catalytic activities were evaluated with a CO oxidation reaction. The surface areas and the surface chemical compositions of Sm, Fe, O and C were strongly dependent on the preparation methods and calcination temperatures. On the basis of such the characteristics on the surface the factors controlling the catalytic activity are discussed.

Effect of precipitation route on the properties of antimony trioxide

Antimony trioxide was prepared, using antimony potassium tartarate as starting material, via forward and reverse precipitation technique. The characteristics of the resulting antimony oxides were determined by BET surface area method, differential thermogravimetry analysis (DTG), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and SEM. The DTG curves for all uncalcined samples showed only a single endothermic peak which indicated that the sample is antimony trioxide. Unlike forward precipitation technique which resulted in a single antimony trioxide phase which is senarmontite, reverse precipitation technique produced antimony trioxide with both senarmontite and valentinite phase. Upon calcinations at 723 K, a small amount of Sb 2O 4 with cervantite phase was formed at the expense of Sb 2O 3 senarmontite phase as detected from the XRD pattern and infrared spectrum of RSb. The effect of preparation route on the properties of the antimony trioxide produced was clearly demonstrated.

Low-Temperature Synthesis of Porous Praseodymium Oxysulfate Oxygen Storage Materials by Using a CTA Template

Porous praseodymium oxysulfate, Pr2O2SO4, with a large oxygen storage capacity was prepared from precipitates, which were formed by adding (NH4)2SO4 to a mixed aqueous solution of Pr(NO3)3 and cationic surfactant, CTA (cetyltrimethyl ammonium ion). Heating the precipitate, Pr-SO4-CTA, yielded directly the single phase of Pr2O2SO4 at a low temperature of 300°C, compared to ≥800°C required for the decomposition of Pr2(SO4)3 (Pr-SO4), and compared to ≥500°C required for the mesophase of Pr and dodecyl sulfate (Pr-DS) in our previous study.1) The effect of preparation route on microstructure and oxygen release/storage property of Pr2O2SO4 was studied by using XRD, TG, SEM, N2 adsorption and catalytic reaction. In contrast to the macropores (≥30 nm in size, 8 m2g-1) of Pr-SO4 and mesopores (≤10 nm, 28 m2 g-1) of Pr-DS, Pr-SO4-CTA showed a wide pore size distribution in the range 2-40 nm and a larger surface area of 37 m2 g-1. The porous structure is very effective in increasing the rate of oxygen release as well as storage. The anaerobic CO oxidation of 1 mass% Pd-loaded Pr2O2SO4 was evaluated in CO/O2 cycled feed stream reactions. It was found that the catalyst prepared from Pr-SO4-CTA achieved the highest catalytic activity due to the high porosity and specific surface area.

The Effect of Preparation Route and Nitrogen Content on Properties of Y- SiAlON Glasses

The Effect of Preparation Route and Nitrogen Content on Properties of Y- SiAlON Glasses