Li^+ extraction/adsorption properties of Li-Sb-Mn composite oxides in aqueous medium

Series Li-Sb-Mn composite oxides with different Sb/Mn molar ratios were obtained by solid state reaction.Their structure,morphology and Li^＋ extraction/adsorption properties were characterized by X-ray diffractometry （XRD）,scanning electron microscopy （SEM） and atomic absorption spectrophotometry （AAS）,respectively.XRD and SEM analyses reveal that the crystal of the products transfers from spinel to orthorhombic phase with the increase of molar ratio of Sb to Mn from 0.05 to 1.00.The Li^＋ extraction and adsorption experiments for these Li-Sb-Mn composite oxides demonstrate that the composite oxides can all be used as lithium inorganic adsorbents.The acid treated spinel Li-Sb-Mn composite oxide with Sb/Mn molar ratio of 0.05 has a high Li^＋ adsorption capacity of 33.23mg/g in lithium solution.The Sb/Mn molar ratio of these Li-Sb-Mn composite oxides should be a crucial factor in determining their structure and Li^＋ extraction and adsorption properties.

Catalytic performance of Ag/Co-Ce composite oxides during soot combustion in O_2 and NO_x:Insights into the effects of silver

The composite oxides xAg/Co_（0.93）Ce_（0.07）（x=Ag/（Co＋Ce） molar ratio）,intended for use as high performance catalytic materials,were successfully prepared via citric acid complexation.The effects of silver on the performance of these substances during soot combustion were subsequently investigated.Under O_2,the 0.3Ag/Co_（0.93）Ce_（0.07） catalyst resulted in the lowest ignition temperature,T_（10）,of197 ℃,while the minimum light-off temperature was obtained from both 0.2Ag/Co_（0.93）Ce_（0.07） and0.3Ag/Co_（0.93）Ce_（0.07） in the NO_x atmosphere.These materials were also characterized by various techniques,including H_2,soot and NO_x temperature programmed reduction,X-ray diffraction,and electron paramagnetic resonance,Raman,X-ray photoelectron,and Fourier transform infrared spectroscopic analyses.The results demonstrated that silver significantly alters the catalytic behavior under both O_2 and NO_x,even though the lattice structure of the mixed oxide is not affected.Surface silver oxides generated under the O_2 atmosphere favor soot combustion by participating in the redox cycles between soot and the silver oxide,whereas the AgNO_3 that forms in a NO_x-rich atmosphere facilitates soot abatement at a lower temperature.The inferior activity of AgNO_3 relative to that of Ag_2O results in the different catalytic performance in the presence of NO_x or O_2.

Efficient removal of chlorophenols from water with a magnetic reduced graphene oxide composite

A magnetic reduced graphene oxide composite(MRGO) was successfully prepared by a simple and green method. MRGO was then used as an adsorbent and found to exhibit enhanced removal efficiency for various chlorophenols(CPs) from water compared with its precursors, graphene oxide(GO) and reduced graphene oxide. The CPs were o-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. Among them, 2,4,6-trichlorophenol, which exhibited the lowest water solubility and highest molecular weight, most easily bound to MRGO. The preferential interactions between MRGO and CPs were hydrophobic interactions(?-? stacking and hydrophobic effect). This result was confirmed by the equilibrium adsorption behavior in which isotherms were all well described by Freudlich model, indicating heterogeneous and multilayer adsorption. Therefore, CP adsorption was more favored under neutral and acidic conditions, and the decreased removal efficiency of MRGO at higher p H levels was due to the improved hydrophilicity of CPs for deprotonation effect. Moreover, MRGO showed fast removal of each CP, achieving adsorption equilibrium within 10.0 min, presented efficient separation from water under an external magnetic field, and was easily regenerated using dilute Na OH aqueous solution after reaching saturated adsorption. Adsorption capacity of the regenerated MRGO had almost no loss until after five cycles. In summary, MRGO was an efficient adsorbent for the removal of various CPs and had considerable application potential in water treatment.

Higher alcohol synthesis over Cu-Fe composite oxides with high selectivity to C_(2+)OH

Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2＋OH and C6＋OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity （GHSV） on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.

Solvothermal synthesis and characterization of nanocrystalline vanadium-chromium composite oxides and catalytic ammoxidation of 2,6-dichlorotoluene

Vanadium‐chromium oxides(VCrO)were usually prepared by high‐temperature solid‐state reactions;however,mixed phases were frequently produced and the morphology of the products was not well controlled.In this work,we prepared amorphous VCrO precursors by using V2O5 and CrO3 and alcohols or mixtures of alcohol and water via solvothermal reaction at 180°C.The precursors were then calcined under nitrogen at various temperatures.The products were characterized by powder X‐ray diffraction,transmission electron microscopy,and X‐ray photoelectron spectroscopy.It was revealed that pure‐phase nanocrystalline orthorhombic CrVO4 was obtained when methanol or methanol/water was used as the solvothermal medium and the precursor was calcined at 700°C.The size of the CrVO4 crystals was around 500 nm when methanol was used,whereas it reduced significantly to less than 50 nm when a mixture of methanol and water was used.The sizes could be effectively tuned from 10 to 50 nm by varying the methanol/water volume ratio.To the best of our knowledge,this is the first report on the synthesis of pure‐phase CrVO4 nanocrystals.The nano‐CrVO4 showed almost the highest catalytic activity for the ammoxidation of 2,6‐dichlorotoluene to 2,6‐dichlorobenzonitrile among the reported bi‐component composite oxides,owing to its smaller particle size,larger specific surface area,and more exposed active centers.

Efficiency and Mechanism of Phosphorus Removal by Coagulation of Iron-manganese Composited Oxide

Iron-manganese composited oxide（FeMnO） was prepared with potassium permanganate and ferrous salt. Interface performance, charge property and structure topography of the FeMnO were investigated. Coagulation efficiency and pollution removal mechanism of the FeMnO were approached. Results show that the main compositions of the FeMnO are δ-manganese dioxide and ferric hydroxide. The specific surface area is about 146.22 m^2/g. The FeMnO contains rich hydroxyl with extremely strong adsorption action and chemical adsorption activity. The zero charge point of the oxide in pure water is about 8.0 of pH value. Under neutral pH value conditions, the FeMnO particle surface carried positive charges. The FeMnO particles are quasi-spherical micro-particles with irregular sizes adjoined each other to form net construction. Phosphorus removal efficiency of the FeMnO is remarkable, the total dissoluble phosphorus of settled water can be reduced below detecting level（0.3 μtg/L） at a FeMnO dosage of 6 mg/L, and total phosphorus below detecting level at a FeMnO dosage of 10 mg/L, for water samples containing total phos- phorus of 1281.70 μg/L and total dissoluble phosphorus of 1187.91 μtg/L. The mechanism of effective coagulation for phosphorus removal is combined results of multiple actions of adsorption, charge neutralization, adsorption/bridging and so on.

Influence of La precursors on structure and properties of CeO_2-ZrO_2-Al_2O_3 composite oxides

Three La-doped CeO2-ZrO2-Al2O3(CZA)composite oxide samples,namely,CZA-I,CZA-II and CZA-III,were prepared following a co-precipitation method in the presence of La2O3,La(NO3)3-6H2O and H[La(EDTA)]-16H2O precursors,respectively.When the precursor samples are sintered at 1000°C,the as-prepared composite oxides mainly exhibit the CeO2-ZrO2 cubic fluorite phase,while theγ-Al2O3 andδ-Al2O3 phases appear when the precursor samples are subjected to sintering at 1100 and 1200°C.CZA-III exhibits improved redox properties after high-temperature treatment compared with CZA-I and CZA-II.CZA-III presents the largest surface area of 97.46 m2/g among the three CZAs when the CZA-III precursor sample is sintered at 1000°C.Furthermore,the corresponding oxygen storage capacity(OSC)is the largest with value of 400.27μmol/g when CZA-III precursor sample is sintered at 1000°C.Additionally,CZA-III exhibits the best thermal stability and the highest reduction temperature.However,by increasing the sintering temperature to 1200°C,there is a dramatic decline in the properties of surface area and OSC.And a decrease for CZA-III in surface area by 58.94%and a decrease of the OSC value by 74.56%are observed.

Synthesis, Characterization of Mesoporous Al-Mg Composite Oxide and Catalytic Performance for Oxyethylation of Fatty Alcohol

A mesoporous Al-Mg composite oxide with a hexagonal structure was synthesized with aluminium nitrate and magnesium nitrate as the reagents and sodium dodecyl sulfate（SDS） as the template in the presence of ethylenediamine. The XRD, nitrogen adsorption-desorption and TEM studies indicate that the composite has a hexagonal framework structure and an average pore diameter of 2. 6 nm. The TG/DTA spectra indicate that the decomposition and the removal of the occluded surfactant of the sample take place in a range of 230-550 ℃. The mesoporous Al-Mg composite oxide exhibites a highly catalytic activity for the oxyethylation of fatty alcohols. Narrow-range distributed ethoxylates are formed in the presence of the mesoporous Al-Mg composite oxide catalyst. The distribution selectivity coefficient（Cx） is 24 when the mesoporous Al-Mg composite oxide was used as a catalyst for the oxyethylation of octanol and the average adduct degree of ethoxylates is 6. 4.

Application of CO_2-TPD in the Synthesis of Composite Oxides from Metal-Organic Precursors

CO2-TPD was demonstrated an effective way to investigate the phase formation during pyrolysis for the preparation of composite oxides using metal-organic molecules as precursors.Based on the CO2-TPD results, it was found that calcination condition had deep effect on the carbonate formation and the minimum firing temperature to acquire pure phase composite oxide.An optimized calcination schedule was then developed.

Formation and capacitance properties of Ti-Al composite oxide film on aluminum

Al specimens were covered with TiO2 film by sol-gel dip-coating and then anodized in ammonium adipate solution.The structure,composition and capacitance properties of the anodic oxide film were investigated by transmission electron microscopy (TEM),Auger electron spectroscopy (AES),X-ray diffractometry (XRD) and electrochemical impedance spectroscopy (EIS).It was found that an anodic oxide film with a dual-layer structure formed between TiO2 coating and Al substrate.The film consisted of an inner Al2O3 layer and an outer Ti-Al composite oxide layer.The thickness of layers varied with the number of times of sol-gel dip-coating.The capacitance of anodic oxide films formed on coated specimens was at most 80% higher than that without TiO2.In film formation mechanism,it was claimed that the formation of composite oxide film was mainly affected by the structure of micro-pores network in TiO2 coating which had an influence on Al3+ and O2? ions transport during the anodizing.

Synthesis of optically active lactide catalyzed by nanocrystals of La-Ti composite oxides

With sol-gel method,nanometer La-Ti composite oxides were prepared.By means of atomic force microscope,the surface pattern,particle size distribution and specific surface area were studied.The newly prepared nanocrystals of La-Ti composite oxides were used as the catalysts to catalyze the dehydration of external compensated lactic acid to lactide.The lactide product was measured by polarimeter and micropolariscope.The results demonstrate that the ratio between D-lactide and L-lactide will not be equal to 1-1 if nanocrystals of La-Ti composite oxides are used as the catalysts,which implies,that nanocrystals of La-Ti composite oxides may be potential catalysts with a good selectivity.

Electrical and optical properties of indium tin oxide/epoxy composite film

The electrical and optical properties of the indium tin oxide （ITO）/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the vicinity of a critical volume fraction have been found within the framework of percolation theory. A conductive and insulating transition model is extracted by the ITO particle network in the SEM image, and verified by the resistivity dependence on the temperature. The dependence of the optical transmittance on the particle size was studied. Further decreasing the ITO particle size could further improve the percolation threshold and light transparency of the composite film.

Preparation and reaction mechanism of novel Ce_(x)Co_(y)Cuz oxide composite catalysts towards oxidation of o-xylene

Ce_(x)Co_(y)Cuzoxide composite catalysts were prepared by using polyethylene glycol, citrate sol-gel method combined with PMMA template for the oxidation of o-xylene. The catalysts were characterized by the Xray diffraction(XRD), H2-temperature programmed reduction(H2-TPR), X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FT-IR), etc. The catalytic activity for o-xylene was investigated. The catalytic degradation pathway and mechanism of o-xylene were inferred. The results show that Ce O_(2)is mainly present on the surface of all catalysts. The surface area of Ce_(2)Co1Cu1is up to 77.2 m^(2)/g, and the average pore size is 10.62 nm. It exhibits redox and sufficient Ce^(4+)and Ce^(^(3+)), and reactive oxygen species, and has maximum O-H and C=O in the five catalyst samples. The catalytic activity of Ce2Co1Cu1is the best at low temperature, with the T50and T90values of 235 and 258°C at a space velocity of 32000 h-1, respectively. The o-xylene is oxidized to o-methyl benzaldehyde, and then further oxidized to o-methylbenzoic acid, and finally CO_(2)and H2O are formed.

Efficient Thickness of Solid Oxide Fuel Cell Composite Electrode

The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transportation, and the microstructure characteristics of the electrode. The efficient thickness, which is defined as the electrode thickness corresponding to the minimum electrode polarization resistance, is formulated as a function of charge transfer resistivity, effective resistivity to ion and electron transport, and three-phase boundary length per unit volume. The model prediction is compared with the experimental reports to check the validity. Simulation is performed to show the effect of microstructure, intrinsic material properties, and electrode reaction mechanism on the efficient thickness. The results suggest that when an electrode is fabricated, its thickness should be controlled regarding its composition, particle size of its components, the intrinsic ionic and electronic conductivities,and its reaction mechanisms as well as the expected operation temperatures. The sensitivity of electrode polarization resistance to its thickness is also discussed.

Structure and stability of Li-Mn-Ni composite oxides as lithium ion sieve precursors in acidic medium

A series of spinel Li-Mn-Ni composite oxides with theoretical chemical formula of LiNixMn2-xO4 （0〈_x〈_1.0） were synthesized by liquid phase method. Their structure and morphology were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）, respectively. The stability of these Ni-substituted spinel oxides prepared at different temperatures was investigated in acidic medium as well. The results show that Ni can be brought into the spinel framework completely to form well-crystallized product when x〈_0.5 and the optimized synthesis temperature is 800℃. LiNi0.4Mn1.6O4 prepared at 800℃ can maintain the spinel structure and morphology with Li extraction ratio of 30.37%, Mn extraction ratio of 8.78% and Ni extraction ratio of 1,82% during acid treatment. The incorporated Ni not only inhibits the dissolution of Mn, but also reduces the extraction of Li due to the lattice contraction

Preparation of La-Ti Composite Oxide Nanocrystal and Examination of Their Surface Topography with Atomic Force Microscope

With sol-gel method, nanometer La-Ti composite oxide was successfully prepared at a low temperature (750～800C) using polyethylene glycol as dispersant. By means of atomic force microscope, the surface pattern, particle size distribution, and specific surface area were studied. The compound particle surface appears as a smooth sheet, the mean size of the compound is 25.38 nm. On the specific surface, the particle erects at a height of 4.69 nm. The surface area is 58.90 nm2. The La-Ti composite oxide nanocrystal prefers to narrow and even particle size distribution and the homogeneity of surface topography.

Preparation of La_(0.9)K_ (0.1)CoO_3 Perovskite Composite Oxide

Two methods for preparing La0.9K0.1CoO3 perovskite composite oxides.traditional solid state reaction method and sol-gel method.were compared.The characteristics of the powders,such as purity.particle diameter,BET surface area,pore diameter,were inrestigated by using TG-DTA,XRD,SEM and BET methods.The experimental results shou that La0.9K0.1CoO3 perorskite composite oxide can be obtained by using the two methods.The purity of La0.9K0.1CoO3 powders can be increased by raising the calcining temperature while the particle diameter increased and BET surface area decreased.At the same calcining temperature,the properties of the La0.9K0.1CoO3 powders synthesized by the sol-gel method are superior to those synthesized by the solid state reaction method.such as purer phase,smaller particle diameter,which can be used as a satisfactory catalyst in diesel waste gas cleaning.

Characteristics of Magnesium-iron-aluminium Composite Oxides and Their Influence on Properties of Magnesia-based Bricks

The composition,structure and micro-morphology of magnesium- iron- aluminum composite oxides were investigated using various methods such as XRF,SEM,EDS,XRD and KMn O4-titration. Compared to hercynite,the composite oxides have completely different phases including solid solution（ Mg O）0. 77（ Fe O）0. 23,composite spinel Mg Fe0. 2Al1. 8O4 and a small amount of Mg Fe2O4. The composite oxides exhibit excellent corrosion resistance to cement clinker and potassium salts.The products produced by magnesite and the composite oxides show better performance than magnesia- hercynite bricks,especially the corrosion resistance and thermal shock resistance.

Synthesis and characterization of porous cobalt oxide/copper oxide nanoplate as novel electrode material for supercapacitors

A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide（CTAB） and polyvinylpyrrolidone（PVP） on the morphology and electrochemical performance of the composite were investigated. Powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and nitrogen adsorption-desorption experiment were employed to characterize the microstructures and morphologies of the composite. Meanwhile, the electrochemical performances of the samples were studied using cyclic voltammetry（CV）, galvanostatic charge-discharge test and electrochemical impedance spectroscopy（EIS）. The results show that the porous Co3O4/Cu O-CTAB nanoplates own the best performance and exhibits a high specific capacitance of 398 F/g at 1 A/g with almost 100% capacitance retention over 2000 cycles, and it retains 90% of capacitance at 10 A/g.

Bacterial Cellulose Templated p-Co3O4/n-ZnO Nanocomposite with Excellent VOCs Response Performance

In this work,p-type Co3O4 decorated n-type ZnO(Co3O4/ZnO)nanocomposite was designed with the assistance of bacterial cellulose template.Phase composition,morphology and element distribution were investigated by XRD,SEM,HRTEM,EDS mapping and XPS.Volatile organic compounds(VOCs)sensing measurements indicated a noticeable improvement of response and decrease of working temperature for Co3O4/ZnO sensor,in comparison with pure ZnO,i.e.,the response towards 100 ppm acetone was 63.7(at a low working temperature of 180℃),which was 26 times higher than pure ZnO(response of 2.3 at 240℃).Excellent VOCs response characteristics could be ascribed to increased surface oxygen vacancy concentration(revealed by defect characterizations),catalytic activity of Co3O4 and the special p-n heterojunction structure,and bacterial cellulose provides a facile template for designing diverse functional heterojunctions for VOCs detection and other applications.