Dual-functionalization based on combination of quercetin compound and rare earth nanoparticle

While the nanoparticles like La2O3 and other rare earth oxides were believed to be able to provide effective scavenging hydroxyl radical.Quercetin,a hydrophobic agent,showed some potential antibacterial activity.The present work successfully performed the surface modification of rare earth nanoparticle using facile and general strategy.In specific,the hydrophobic quercetin was grafted on the rare earth nanoparticle through the coupling with silane.The surface modified nanoparticle was characterized by Fourier-transform infrared(FTIR),thermogravimetric analysis(TGA),and scanning electron microscopy(SEM).The surface modification helped to retain both the scavenging hydroxyl radical property of rare earth nanoparticle and the antibacterial activity of quercetin.This dual-function properties showed potential for application in the development of biomedicine such as antioxidant,anti-inflammatory,antibacterial and anticancer.     

Rare earth oxide modified Cu-Mn compounds supported on TiO₂ catalysts for low temperature selective catalytic oxidation of ammonia and in lean oxygen

Selective catalytic oxidation(SCO) of ammonia was carried out over Cu-Mn compounds catalysts modified with trivalent rare earth oxide Ce2O3 and La2O3 respectively.TiO2 was used as support and different ratio of O2 were tested in order to find an appropriate O2 concentration(vol.%),and the results showed that 1%O2(vol.%) was propitious to SCO of ammonia.The effects of the two rare earth oxides modified catalysts Ce2O3-Cu-Mn/TiO2 and La2O3-Cu-Mn/TiO2 on the catalytic activity and selectivity of ammonia oxidation were investigated under the reaction condition of 500 ppm ammonia,1%O2(vol.%),at the temperature from 125 to 250 oC.The results revealed the beneficial role of Ce2O3 and La2O3 in catalytic activity at low temperature and lean oxygen concentration,while the modification with Ce2O3 and La2O3 led to the negative influence on N2 selectivity.For the catalysts modified with Ce showed lower NO and N2O selectivity than the catalysts modified with La,then the effects of different Ce loadings on catalytic activity and selectivity were also considered,in combination with catalysts preparation methods,which include incipient wet impregnation,sol-gel method and co-precipitation.Results revealed that the catalysts prepared by sol-gel method obtained preferable catalytic activity compared with the others,reaching 99% ammonia at 200 oC,whereas 96% NO was detected.It also indicated that different catalyst preparation method significantly determined production distribution.     

Influence of LaCl3 addition on microstructure and properties of nickel-electroplating coating

The influence of rare earth chloride LaCl3 ·7H2O addition on the microstructural features, phase structure, corrosion resistance and microhardness of nickel-electroplating was investigated. The Watts-type with different additive amounts of LaCl3·7H2O(0-1.2g/L) were used in the experiment. Surface morphologies of coatings were examined by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) was used to measure the coatings’ grain size and the microstructure of coatings was detected by X-ray diffraction (XRD). Corrosive investigation was carried out in 3.5 wt.% NaCl solution. The microhardness values of the coatings with different amounts of LaCl 3·7H2O were measured, and the mechanism of the variation in microhardness was studied. Results showed that the addition of rare earth lanthanum refined the grain size and improved the surface consistency of the coatings, meanwhile the microhardness and corrosion property of coatings were improved and achieved a maximum with arround 1.0g/L LaCl 3·7H2O addition in electrolyte. The preferred growth orientation of lanthanum doped coating was crystal face (200), meanwhile the La2 Ni7 phase was detected in the nickel coating by XRD and this was due to the induced co-deposition of elements La and Ni. The reason maybe was that the special out-layer electronic structure of element La raised the polarization of Ni cathode deposition, accelerated the nucleation of Ni and reduced hydrogen evolution from cathode surface.     

Nano-preparation promoting effectively luminescent properties of one-dimensional rare earth oxides

Rare earth (La,Nd and Tb) oxides with one-dimensional micro/nanostructures were synthesized hydrothermally under facile and mild conditions with two surfactants, and characterized by X-ray diffraction (XRD), thermal gravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence. The results showed that the synthesized rare earth oxides behaved regular nano-and micro-scale structures. And the morphologies of samples depended on the radii of rare earth ions, with the help of two surfactants of sodium dodecyl sulfonic and PEG 600. Nanocrystalline La2O3:Eu3+ possessed good photoluminescence (PL) property and might be used as a nanosized phosphor, its PL intensity was altered by the doping Eu3+ concentration and the optimum concentration of Eu3+ was 3 mol.%. In comparison with bulk Eu3+/La2O3, Eu3+/nano-La2O3 showed better photoluminescence property, nearly equal to that of nanocrtstal-line La2O3:Eu3+. Tb4O7 microwires showed interesting photoluminescence properties.     

Zirconia modified monolithic macroporous Pt/CeO2/Al2O3 catalyst used for water-gas shift reaction

Monolithic macroporous Pt/CeO2/Al2O3 and zirconia modified Pt/CeO2/Al2O3 catalysts were prepared by using concentrated emulsions synthesis route. The catalytic performances over the platinum-based catalysts were investigated by water-gas shift (WGS) reaction in a wide temperature range (180-300 oC). The samples were characterized with thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and temperature programmed reducti...     

Rare earth oxide modified Cu-Mn compounds supported on TiO2 catalysts for low temperature selective catalytic oxidation of ammonia and in lean oxygen

Selective catalytic oxidation (SCO) of ammonia was carried out over Cu-Mn compounds catalysts modified with trivalent rare earth oxide Ce₂O₃ and La₂O₃ respectively. TiO₂ was used as support and different ratio of O₂ were tested in order to find an appropriate O₂ concentration (vol.%), and the results showed that 1%O₂ (vol.%) was propitious to SCO of ammonia. The effects of the two rare earth oxides modified catalysts Ce₂O₃-Cu-Mn/TiO₂ and La₂O₃-Cu-Mn/TiO₂ on the catalytic activity and selectivity of ammonia oxidation were investigated under the reaction condition of 500 ppm ammonia, 1%O₂ (vol.%), at the temperature from 125 to 250 °C. The results revealed the beneficial role of Ce₂O₃ and La₂O₃ in catalytic activity at low temperature and lean oxygen concentration, while the modification with Ce₂O₃ and La₂O₃ led to the negative influence on N₂ selectivity. For the catalysts modified with Ce showed lower NO and N₂O selectivity than the catalysts modified with La, then the effects of different Ce loadings on catalytic activity and selectivity were also considered, in combination with catalysts preparation methods, which include incipient wet impregnation, sol-gel method and co-precipitation. Results revealed that the catalysts prepared by sol-gel method obtained preferable catalytic activity compared with the others, reaching 99% ammonia at 200 °C, whereas 96% NO was detected. It also indicated that different catalyst preparation method significantly determined production distribution.     

Effects of rare earth on inclusions and corrosion resistance of 10PCuRE weathering steel

The types,morphologies and distributions of nonmetallic inclusions in Cu-P weathering steels with and without rare earth were analyzed through a quantitative image analyzer,scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)attached to SEM.Solid-soluble content of rare earth in the steels was analyzed by non-aqua electroanalysis and ICP.The results showed that rare earth modified the types and the morphologies of inclusions in the weathering steels.The small spherical rare earth oxysulfides and rare earth sulphides replaced the elongated MnS inclusions in the RE weathering steels.The rare earth inclusions dispersedly distributed and most inclusions were smaller than 2 μm in size.The optimum content of RE was 0.0065%-0.016% for 10PCuRE weathering steels containing about0.002% oxygen and 0.004% sulfur.Solid-soluble content of rare earth in steels was(14-20)x 10-6,which can act as a micro-alloying element.The corrosion resistance of 10PCuRE weathering steels and Q235 were studied by dry-wet cyclic immersion test.Their corrosion rates were obtained respectively.The polarization curves and pitting corrosion behaviors of weathering steels with and without rare earth were measured by electrochemical methods.The corrosion resistance of Cu-P weathering steels was improved by adding an appropriate amount of rare earth.Less and fewer rare earth inclusions largely decreased pitting susceptibility and rate of pit propagation.The pitting potential and the resistance against pitting corrosion of the RE weathering steel were significantly improved due to the modification of rare earth to inclusions.     

Zn-Al-La hydrotalcite-like compounds as heating stabilizer in PVC resin

ZnAlLa-CO 3 layered double hydroxides (LDHs) with different Zn/Al/La molar ratios were prepared by the constant pH coprecipitation method. The synthetic materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller method (BET) and particle analysis. The results showed that the hydrotalcite-like materials had a layered structure. The ZnAlLa-CO 3 -LDHs as stabilizers were mixed with PVC resin. The tests of thermal aging, mass loss test and Congo red for the PVC composites were carried out at 180±1 oC, respectively. The results showed that ZnAlLa-CO 3 LDHs used as single thermal stabilizers could enhance both the long-term thermal stability and initial thermal stability of PVC, and 2.4 phr (parts per hundred PVC resin) ZnAlLa-CO 3 -LDHs with Zn/Al/La (molar ratio)=20/8/2 had a better stabilizing effect on PVC than others. Compared with single thermal stabilizers, the composite thermal stabilizers including 0.3 phr calcium stearate (CaSt 2 ), 0.4 phr β-diketone and 2.4 phr ZnAlLa-CO 3 -LDHs significantly enhanced the thermal stability of PVC sample. And rare earth ion could optimize the conformation of PVC and refrain the initiation of the thermal stability and the thermal stable time was over 220 min. The main reason could be concluded to the special structure of rare earth ion, which had longer atom radius and more coordination numbers. So the rare earth ion (RE δ+ ) could react with the labile chlorine atoms (Cl r- ) to form a stable coordinate complex.     

稀土改性镍催化剂对CO2甲烷化反应的影响

以稀土为助剂 ,金属镍为活性组份 ,研究了不同稀土对镍催化剂的改性作用 ,同时用活性比表面、H2 -TPD、CO2 - TPD及 XPS等方法对催化剂进行了表征。结果表明 ,稀土对镍催化剂的 CO2 甲烷化活性有明显的促进作用 ,其中以稀土 Sm的改善效果最好 ;海泡石和 Sm既能增大镍催化剂的活性比表面积 ,又能提高 H2 和 CO2 的吸附量 ,同时降低反应的活化能 ,增大镍上的电子云密度。     

Effect of tourmaline additive on the crystal growth and activity of LaCoO3 for catalytic combustion of methane

LaCoO3/tourmaline was prepared as catalysts on the methane catalytic combustion. As additive tourmaline, its effect on crystal growth and catalytic activity of LaCoO3, were investigated via X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), H2-temperature programmed reduction(H2-TPR) and catalyst evaluation techniques. SEM and TEM indicated that the spontaneous polarizability of tourmaline made LaCoO3 particles grow dispersedly on tourmaline, alleviated the agglomeration and exposed more reactive sites. It was a main influence leading to the improvement of catalysts activity, exposed via catalyst evaluation device. Among the different additive proportion of compound samples, the 2% tourmaline added LaCoO3 showed an obvious enhancement activity compared to non-tourmaline sample—the light-off temperature was 454 °C and CH4 reached the full conversion at 563 °C.     

Effect of Pd, Cu, and Ni additions on the kinetics of NiCl2 reduction by hydrogen

Differnetial thermal analysis (DTA) and thermal gravimetric analysis (TGA), at a heating rate of 10 °C/min, revealed a complete reduction of NiCl₂ by hydrogen in a temperature interval of 375 °C to 450 °C. However, addition of 0.1 mass pct of Pd, Cu, or Ni to the sample caused the reduction to occur at considerably lower temperatures, in the rather narrow range of 315 °C to 370 °C. The activation energy of NiCl₂ reduction by hydrogen (between 300 °C and 550 °C) without additives is 54 kJ/mol, and with Pd and Cu or Ni added, under isothermal conditions (from 260 °C to 380 °C), is 33 and 50 kJ/mol, respectively. These values confirm a positive effect of additives on the reduction kinetics. The positive effect of Pd is a consequence of the dissociation and spillover of hydrogen, whereas in the case of Cu and Ni(HCOO)₂, it is manifested in a decrease in bonds energy in the nickel lattice because of good Cu solubility, and in the formation of artificial nickel nuclei that intensify the reduction, respectively. Scanning electron microscopy (SEM) analysis of nickel powders obtained under isothermal conditions shows relatively rounded spherical particles (0.321 to 0.780 μm in size) of powder samples with additives, and particles of irregular shape (2.085 μm mean size) of the sample without additives. This illustrates the positive effect of Pd, Cu, or Ni added in the reduction process, in decreasing the size of nickel particles and in the production of a more uniform particle shape.     

CuO-CeOe/AleO3/FeCrAl monolithic catalysts prepared by in situ combustion synthesis method for preferential oxidation of carbon monoxide

This work described in situ combustion synthesis method for depositing CuO-CeO2 on the FeCrAl honeycomb supports.The in-fluence of the solution concentration and the role of the additive were studied and analyzed by scanning electron microscopy (SEM),X-ray diffractometer (XRD),and temperature programmed reduction (TPR) techniques.The results showed that 200 g/L of the active solution was the most appropriate concentration for preparing the monolithic catalysts,and the additives of praseodymium and lanthanum improved the adhesion stability of the monolithic catalysts.The addition of Pr did not greatly affect the catalytic performance,but CO could not be totally converted into CO2 after the addition of La into the CuO-CeO2/Al2O3/FeCrAl catalysts.     

Toxicological effects and risk assessment of lanthanum ions on leaves of Vicia faba L.seedlings

Vicia faba L.seedlings were hydroponically cultivated in 0-12 mg/L of extraneous lanthanum(La) for 15 d to investigate ecotoxicological effects and risk assessment of rare earth elements(REEs).The results showed that reactive oxygen species(ROS) production suchas superoxide radical(O2.-) and hydrogen peroxide(H2O2) were overproduced at higher concentrations of La,resulting in oxidatively modified proteins and shoot growth retardation.While,superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX) and guaiacolperoxidase(GPX) isoenzymes were elevated to some extent to eliminate excess of ROS.HSP70 production and endopeptidase isoenzymeswere also enhanced,which were involved in repairing or degradation of the oxidatively modified proteins due to La.Thus,the antioxidantisoenzymes,endoprotease isoenzymes and HSP70 worked cooperatively to alleviate the La-induced oxidative damage.The significant enhancement of CAT and APX isoenzymes and HSP70 could also be used as early bioindicators of La-polluted solution.The threshold doserange was firstly delimited as 1-2 mg/L of extraneous La,corresponding to 7.34-9.37 μg/g dry weight in the leaves.These results would behelpful to further understand the toxicological effects and possible mechanisms of REE(s) on crop seedlings.     

Effect of rare earth addition on structure and properties of Ni-P coating on SiCp/Al composites

The aim of this work was to improve the properties of Ni-P coating on SiCp/Al composites. The effect of rare earths addition on Ni-P coating structure was investigated by means of scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and electrochemistry methods. The results showed that as Y or La concentration was 0.15 g/L in plating solution, the highest value of deposition rate of Ni-P coating was found. And the structure of the obtained coating was modified...     

Oxidative dehydrogenation of ethane over RE-NiO （RE=La, Nd, Sm, Gd） catalysts

RE-NiO(RE=La,Nd,Sm,Gd) catalysts were prepared by a modified sol-gel method and characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),BET surface area analysis,H 2 temperature-programmed reduction(H 2-TPR),and O 2 temperature-programmed desorption(O 2-TPD).The oxidative dehydrogenation of ethane(ODHE) to ethylene was applied to evaluate catalytic performance of the samples.The results showed that the doping of RE affected the physicochemical properties of the catalysts.The strong interaction between Gd and NiO played an important role in the lessened reducibility and the distribution of adsorbed oxygen species,consequently influenced the catalytic performance.The best yield to ethylene of 29% was obtained over the Gd-NiO catalyst with an ethane conversion of 56%.     

Phase change,micro-structure and reaction mechanism during high temperature roasting of high grade rare earth concentrate

The deposit of Bayan Obo in Inner Mongolia is the world's largest rare earth element(abbreviated as REE)resource.The exploration of the theory of mineral formation of Bayan Obo is an important foundation for mineralogical research,and is the scientific basis for mining,industrial beneficiation,smelting and extraction,and processing and utilization.With the rapid development of science and technology,the demand for the utilization of rare earth elements is increasing,and the separation process between rare earth elements needs to be developed.The purpose of this paper is to provide high temperature experimental information for the formation and application of rare earth minerals.To this end,the mineral evolution of high-grade rare earth concentrates with increasing temperature and the migration of rare earths at different stages and their reaction mechanisms were studied.According to thermogravimetric analysis and differential scanning calorimetry(TG-DSC),calcination was carried out at different temperature ranges,and the calcined products were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron micro scope and energy dispers ive spectrometer(SEM-EDS)and other analytical techniques.The re sults are shown in this process,the ra re earth phase is first converted into rare earth oxide and rare earth oxyfluoride.As the temperature increases,Ca_5(PO_4)_3 F and a large number of self-shaped spherical Ca-RE-OF and Ca-RE-PO_4 particles are formed,and the separation of La and Ce elements is discovered.Acco rding to the phase diagram analysis,the production of Ca_5(PO_4)_3 F is due to the reaction of monazite and fluorite,and the phases CeF_2 and Ce F_3 are formed during the reaction.When it reaches 1500℃,barium ferrite is produced and a new substance containing Ba~(2+)is formed.     

Study on Aldol Condensation of HCHO and CH3 CHO over MgO Catalysts Modified by Lanthanum and Cerium

Aldol condensation of HCHO and CH3CHO over MgO, modified MgO and Al2O3 with rare earth oxides,was studied. The measurement of adsorption of pyrrole on catalysts by in-situ FT-IR and NH3 TPD indicated thatthe addition of elements La or Ce into MgO increased the acidity of the solid. In-situ FI‘-IR showed that the activation of - C = O in HCHO adsorbed on CeO-MgO and La2O3-MgO occurred. The measurement of catalytic activity implied that the modified catalysts can promote the formation of pentaerythritol, dipentaerthritol and tripentaerythritol.     

Catalytic combustion of soot over Ru-doped mixed oxides catalysts

We employed modified substrates as outer heterogeneous catalysts to reduce the soot originating from the incomplete diesel combustion. Here, we proposed that ceria（CeO2）-based catalysts could lower the temperature at which soot combustion occurred from 610 oC to values included in the operation range of diesel exhausts（270–400 oC）. Here, we used the sol-gel method to synthesize catalysts based on mixed oxides（ZnO：CeO2） deposited on cordierite substrates, and modified by ruthenium nanoparticles. The presence of ZnO in these mixed oxides produced defects associated with oxygen vacancies, improving thermal stability, redox potential, sulfur resistance, and oxygen storage. We evaluated the morphological and structural properties of the material by X-ray diffraction（XRD）, Brumauer-emmett-teller method（BET）, temperature programmed reduction（H2-TPR）, scanning electron microscopy（SEM）, and transmission electron microscopy（TEM）. We investigated how the addition of Ru（0.5 wt.%） affected the catalytic activity of ZnO：CeO2 in terms of soot combustion. Thermogravimetric analysis（TG/DTA） revealed that presence of the catalyst decreased the soot combustion temperature by 250 oC, indicating that the oxygen species arose at low temperatures, which was the main reason for the high reactivity of the oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy（DRS） showed that the catalyst containing Ru on the mixed oxide-impregnated cordierite samples efficiently oxidized soot in a diesel stationary motor： soot emission decreased 80%.     

Synthesis of yttrium and cerium doped ZnO nanoparticles as highly inexpensive and stable photocatalysts for hydrogen evolution

Yttrium and cerium co-doped ZnO nanoparticles were synthesized by combustion route and characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),energy dispersive spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS),UV-visible diffuse reflectance spectroscopy(UV-vis DRS),photoluminescence(PL)and electrochemical impedance spectroscopy(EIS)techniques.The introduction of yttrium ions has efficiently increased the relative percentage of Ce³⁺ions in ZnO.Yttrium and cerium co-doped ZnO shows efficient photo activity for hydrogen evolution(10.61 mmol/((g·h))higher than previously reported optimal value for rare earth codoped ZnO photocatalysts.This remarkably increased hydrogen evolution can be ascribed to the synergy between electronic anchoring effect of Y³⁺/Y²⁺and Ce⁴⁺/Ce³⁺redox couples.This report presents new idea for the synthesis of efficient photocatalyst using economical route and ion anchoring effect.The hydrogen evolution was also tested using Na₂S and Na₂SO₃as electron donors under visible light illumination.The synthesized photocatalysts also exhibit high stability.     

Improving Corrosion Resistance of Cf/Mg Composites using Rare Earth Conversion Coatings

The surface of carbon fiber reinforced Mg matrix (Cf/Mg) composites was modified by treatment of rare earth conversion coating, and nontoxic, non-pollution Ce conversion coatings were prepared. The effect of the coatings on corrosion behaviors of composites was investigated by electrochemical polarization technology and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The higher Ecorr and lower icorr were obtained by Ce conversion coatings. EIS results showed that the higher values of R2 were obtained by treatment containing CeCl3, the high corrosion resistance occured in treatment containing CeCl3, the low corrosion resistance in uncoating sample, the coating of treatment containing Ce(NO3)3 was medium. The microstructure of Ce conversion coatings was observed by scanning electron microscopy (SEM), and the elements of corresponding for coatings was characterized by energy dispersive spectrometer (EDS). The micro-cracks and Ce-riched spherical particles were characteristics of these coatings.