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.

Laser‑Induced and MOF‑Derived Metal Oxide/Carbon Composite for Synergistically Improved Ethanol Sensing at Room temperature

Advancements in sensor technology have significantly enhanced atmospheric monitoring.Notably,metal oxide and carbon(MO_(x)/C)hybrids have gained attention for their exceptional sensitivity and room-temperature sensing performance.However,previous methods of synthesizing MO_(x)/C composites suffer from problems,including inhomogeneity,aggregation,and challenges in micropatterning.Herein,we introduce a refined method that employs a metal–organic framework(MOF)as a precursor combined with direct laser writing.The inherent structure of MOFs ensures a uniform distribution of metal ions and organic linkers,yielding homogeneous MO_(x)/C structures.The laser processing facilitates precise micropatterning(<2μm,comparable to typical photolithography)of the MO_(x)/C crystals.The optimized MOF-derived MO_(x)/C sensor rapidly detected ethanol gas even at room temperature(105 and 18 s for response and recovery,respectively),with a broad range of sensing performance from 170 to 3,400 ppm and a high response value of up to 3,500%.Additionally,this sensor exhibited enhanced stability and thermal resilience compared to previous MOF-based counterparts.This research opens up promising avenues for practical applications in MOF-derived sensing devices.

One-pot Synthesis of MoO_(3)/PI Composite with Enhanced Photocatalytic Performance for Oxidative Coupling of Amines to Imines

Organic-inorganic MoO_(3)/PI(MoPI)composites were prepared using a simple one-pot thermal copolymerization method.The resulting composites exhibited enhanced photocatalytic activity for the selective oxidation of benzylamine to N-benzylidene benzylamine(N-BDBA)in ambient air under simulated solar light irradiation compared to pristine MoO_(3) or polyimide(PI).In particular,the MoPI composite with a 0.3:1 molar ratio of Mo to melamine,referred to as MoPI-0.3,demonstrated the best performance in the photo-oxidation of benzylamine,achieving a benzylamine conversion of 95%with a N-BDBA selectivity exceeding 99%after 3 h irradiation.The enhanced photocatalytic activity of the MoPI-0.3 catalyst was attributed to the formation of a direct Z-scheme heterojunction between MoO_(3) and PI,facilitating more efficient separation of the photoinduced electrons and holes.Additionally,the MoPI-0.3 composite maintained considerably high activity over four consecutive cycles,highlighting its good stability and recyclability.Furthermore,the MoPI-0.3 composite could photo-oxidize benzylamine derivatives and heterocyclic amines to their corresponding imines,demonstrating the universal applicability of this composite catalyst.

Bonding enhancement of cold rolling TA1 P-Ti/AA6061 composite plates via surface oxidation treatment

TA1 P-Ti/AA6061 composite plate was produced by oxidizing the surface of the titanium plate and adopting a cold roll bonding process.The results revealed that the oxide film(Ti6O)prepared on the surface of TA1 pure titanium was easy to crack during the cold roll bonding,thereby promoting the formation of an effective mechanical interlock at the interface,which can effectively reduce the minimum reduction rate of the composite plates produced by cold rolling of titanium and aluminium plates.Moreover,the composite plate subjected to oxidation treatment exhibited high shear strength,particularly at a 43%reduction rate,achieving a commendable value of 117 MPa.Based on oxidation treatment and different reduction rates,the annealed composite plates at temperatures of 400,450,and 500°C displayed favorable resistance to interface delamination,highlighting their remarkable strength-plasticity compatibility as evidenced by a maximum elongation of 31.845%.

Study on the oxidation mechanism of Al-SiC composite at elevated temperature

Resin-bonded Al-SiC composite was sintered at 1100,1300,and 1500℃ in the air,the oxidation mechanism was investigated.The reaction models were also established.The oxidation resistance of the Al-SiC composite was significantly enhanced with temperature increase.SiC in the exterior of the composite was partially oxidized slightly,while the transformation of metastable Al_(4)C_(3) to stable Al_(4)SiC_(4) existed in the interior.At 1100℃,Al in the interior reacted with residual C to form Al_(4)C_(3).With increasing to 1300℃,high temperature and low oxygen partial pressure lead to active oxidation of SiC,and internal gas composition transforms to Al_(2)O(g)+CO(g)+SiO(g)as the reaction proceeds.After Al_(4)C_(3) is formed,CO(g)and SiO(g)are continuously deposited on its surface,transforming to Al_(4)SiC_(4).At 1500℃,a dense layer consisting of SiC and Al_(4)SiC_(4) whiskers is formed which cuts off the diffusion channel of oxygen.The active oxidation of SiC is accelerated,enabling more gas to participate in the synthesis of Al_(4)SiC_(4),eventually forming hexagonal lamellar Al_(4)SiC_(4) with mutual accumulation between SiC particles.Introducing Al enhances the oxidation resistance of SiC.In addition,the in situ generated non-oxide is uniformly dispersed on a micro-scale and bonds SiC stably.

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.

Effect of mixed rare earth oxides and CaCO_3 modification on the microstructure of an in-situ Mg_2Si/Al-Si composite

The effects of mixed rare earth oxides and CaCO3 on the microstructure of an in-situ Mg2Si/Al-Si hypereutectic alloy composite were investigated by optical microscope,scanning electron microscope,and energy dispersive spectrum analysis. The results showed that the morphol-ogy of the primary Mg2Si phase particles changed from irregular or crosses to polygonal shape,their sizes decreased from 75 μm to about 25 μm,and the compound of both the oxide and CaCO3 was better than either the single mixed rare earth o...

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.

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.

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 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.

High Performance Silicon Nitride-based Composite Materials with Rare-earth Oxides Additives

In the present paper,a silicon nitride-based composite processed with rare-earth oxidesadditives is presented.Its bend strength can be maintained at a value as high as 1000 MPafrom 1000 to 1370℃ and the fracture toughness measures 9-10 MPa·m1/2.The static fa-tigue behavior at 1370℃ of this material is also encouraging.Besides,two another α′/β′sialon composites doped with rare-earth oxides are also described.The effects of processingparameters on the microstructure and the properties of the materials are discussed in somedetails.

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.

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 Polymer-Mineral Nanocomposites Based on Vinyl Monomers and Dispersed Inorganic Oxides

The polymer-mineral composites were synthesized using vinyl monomers styrene, methyl acrylate, and butyl acrylate with nano dispersed oxides Fe2O3, Cr2O3, V2O5 and SiO2 in the presence of benzoyl peroxide and other peroxide initiators. Benzoyl peroxide adsorption on Fe2O3, Cr2O3, and V2O5 surfaces was studied. The adsorption parameters were found: adsorption-desorption equilibrium constants, maximum adsorption, and the area occupied by the molecule benzoyl peroxide on the surface of the adsorbent. The molecular weights of the polymers in the composites and the degree of grafting of the macromolecules of the polymer to the surface of oxides were studied. It has been found that the surface of the dispersed oxides influences the rate of thermal decomposition of the peroxide initiators and the polymerization parameters of the vinyl monomers.

Morphology and Frictional Characteristics Under Electrical Currents of Al_2O_3/Cu Composites Prepared by Internal Oxidation

Two Al2O3/Cu composites containing 0.24 wt.% Al2O3 and 0.60 wt.% Al2O3 separately are prepared by internal oxidation. Effects of sliding speed and pressure on the frictional characteristics of the composites and copper against brass are investigated and compared. The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope （SEM） and energy dispersive X-ray spectrum （EDS）. The results show that the wear resistance of the Al2O3/Cu composites is superior to that of copper under the same conditions, Under a given electrical current, the wear rate of Al2O3/Cu composites decreases as the Al2O3-content increases, However, the wear rates of the Al2O3/Cu composites and copper increase as the sliding speed and pressure increase under dry sliding condition. The main wear mechanisms for Al2O3/Cu composites are of abrasion and adhesion; for copper, it is adhesion, although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.

Preparation and oxidation property of ZrB_2-MoSi_2/SiC coating on carbon/carbon composites

To improve the oxidation resistance of carbon/carbon composites,ZrB2-MoSi2/SiC coating on the carbon/carbon substrate was prepared.The inner coating of SiC was prepared by pack cementation and the outer coating of ZrB2-MoSi2 was prepared by slurry painting.The phase compositions and microstructures of the coating were characterized by XRD and SEM,respectively.The preparation and the high temperature oxidation property of the coated composites were investigated.The results show that the outer coating of carbon/carbon composites is composed of ZrB2,MoSi2 and SiC phases.The mass losses of the ZrB2-MoSi2/SiC coated samples with SiC nano-whiskers after 30 h and 10 h of oxidation at 1 273 K and 1 773 K were,respectively,5.3% and 3.0%.The ZrB2-MoSi2/SiC coated samples exhibit self-sealing performance and good oxidation resistance at high temperature.

Double SiC coating on carbon/carbon composites against oxidation by a two-step method

To improve the oxidation resistance of C/C composites, a double SiC protective coating was prepared by a two-step technique. Firstly, the inner SiC layer was prepared by a pack cementation technique, and then an outer uniform and compact SiC coating was obtained by low pressure chemical vapor deposition. The microstructures and phase compositions of the coatings were characterized by SEM, EDS and XRD analyses. Oxidation behaviour of the SiC coated C/C composites was also investigated. It was found that the double SiC coating could protect C/C composites against oxidation at 1773 K in air for 178 h with a mass loss of 1.25%. The coated samples also underwent thermal shocks between 1773 K and room temperature 16 times. The mass loss of the coated C/C composites was only 2.74%. Double SiC layer structures were uniform and dense, and can suppress the generation of thermal stresses, facilitating an excellent anti-oxidation coating.

C/SiC/MoSi_2-SiC-Si multilayer coating for oxidation protection of carbon/carbon composites

C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the as-received coating were analyzed by scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The results show that the multilayer coating was composed of MoSi2, SiC and Si. It could effectively protect C/C composites against oxidation for 200 h with the mass loss of 3.25% at 1873 K in static air. The mass loss of the coated C/C composites results from the volatilization of SiO2 and the formation of cracks and bubble holes in the coating.