系列层状K2La2Ti3O10的制备及光催化性能

通过固相反应法合成了一系列不同尺寸的K2La2Ti3O10,考察了原料TiO2粒径对固相反应速率及产物尺寸、形貌的影响,得到了不同粒径下原料的最佳配比;以降解甲基橙为探针考察其光催化性能.结果表明减小原料粒径,反应温度降低、速率加快;有利于合成小尺寸、大比表面积(可达11.83 m2·g-1)的层状K2La2Ti3O10,而且光催化性能提高.     

纳米氧化镧的固相合成

以LaCl_3·6H_2O和H_2C_2O_4·2H_2O为原料,用室温固相化学反应首先合成出前驱物草酸镧,经750℃分解3h,得到产物纳米氧化镧。用X-射线粉末衍射和透射电镜对产物的组成、大小、形貌进行表征。结果表明：纳米氧化镧为粒度分布均匀的长方体形结构,平均粒径12nm。并考察了表面活性剂对粒径大小和分散性的影响。     

Synthesis of Ultrafine K2Ln2Ti3O10 by Microemulsion Method and Its Photoactivity Research

A series of uhrafine K2Ln2Ti3O10（Ln = La, Ce, Pr, Nd, Sm, Eu, Dy）photocatalyst was prepared by microemulsion method based on tetrabutyl titanate reacting with potassium hydroxide and lanthanumoxide. The obtained products were characterized by XRD, TEM and UV-Vis spectra. These results indieate that highly ultrafine K2Ln2Ti3O10 can be accessible at lower fabricating temperature and shorter reation time by this approach. In addition, the investigation on their eatalytieal behavior based on the degradation of methyl orange under UV-Vis light suggests that the degradation rate can reach up to 60%.     

A Study on the Thermal Stability of La_2O_3-TiO_2 Supports

In this paper,various techniques including BET,XRD,SEM and XPS were used to study the sintering ofpure and La_2O_3-doped titania.The experimental results show that sintering of titania proceeds via volume diffu-sion.Adding of lanthanum oxide decreases the rate of sintering and hinders the phase transition from anatase torutile crystal by strong surface interaction between the mixed crystals(La_4Ti_9O_(24),La_(0.66)TiO_(2.99))and TiO_2.     

纳米La_2O_3粉晶的制备及其表征

以La(NO_3)_3·6H_2O、NH_4HCO_3和聚乙二醇为原料,利用沉淀法制备了纳米La_2O_3粉体,利用XRD,TG-DTA和TEM等测试方法对干凝胶热分解过程及最终形成的纳米La_2O_3粉体进行了分析和表征,XRD法考察了前驱体在不同热处理条件下产物物相和晶粒度的变化情况,实验结果表明,在适当工艺参数下,前驱体经720℃,1h焙烧所得产物为平均粒径小于50nm的La_2O_3粉体.     

离子交换树脂法制备纳米La_2O_3及表征

以La(NO3)3.6H2O为原料,用强碱性阴离子交换树脂为沉淀剂,制备了纳米La2O3。前驱物及产物进行了TG-DTA、XRD、TEM、HRTEM、SAED、BET等表征。实验结果表明,前驱物是La(OH)3,产物为宽约20nm~25nm、长约为80nm~200nm的板状或棒状La2O3纳米多晶体。     

Ionic liquid mediated morphologically improved lanthanum oxide nanoparticles by Andrographis paniculata leaves extract and its biomedical applications

Greener synthesis of ionic liquid(IL) assisted lanthanum oxide(La_2O_3) nanoparticles(NPs) was followed using Andrographis paniculata leaves extract by hydrothermal method at low temperature,The IL assisted La_2O_3(La_2O_3-IL) NPs were characterized by various properties such as structural,spectral,optical,morphological,and biological studies.Powder X-ray diffraction studies confirm that La_2O_3-IL NPs crystallize in the form of body-centered cubic structure and average crystalline size is shown-43 nm.FTIR and Laser Raman spectroscopy confirm the La-O,O-H and various functional groups.The La-O stretching vibration band attributes at 639 cm~(-1).The optical property of La_2O_3-IL NPs was characterized by UV-Vis and photo luminesce nce spectroscopy.The sharp and intense absorbance peak observed in the UV region at 288 nm can be assigned.In the PL spectrum,we observe two different emission bands like blue and green emission.The morphological and particle size determination were investigated by SEM with EDX spectra and TEM analyses.The agglomerated particles of hexagonal,spherical,and parallelogram shape are observed in the TEM images.The chemical elements,binding energies as well as La metal states on the surface of these synthesized NPs were determined using XPS.La_2O_3 NPs for good biological activities regarding antibacterial and anti-inflammatory potentials could be utilized in different biological applications to the food and biomedical industries.La_2O_3-IL has a high percentage of inhibitions than La_2O_3 and standard diclofenac.     

Can lanthanum doping enhance catalytic performance of silver in direct propylene epoxidation over NaMoAg/SiO_2?

In the attempt to reduce surface free energy of silica to improve interaction of silica with silver, silica was doped by different amounts of low surface energy lanthanum, La_2O_3, through impregnation. The doped and undoped silica were used as supports for preparation of Na/Ag/Mo/La_2O_3-SiO_2 catalysts. Catalytic performances of the catalysts were evaluated in direct epoxidation of propylene(DPO) using molecular oxygen under atmospheric pressure and without adding hydrogen. Adding 5 wt%La to the Na/Ag/Mo/SiO_2 catalyst improves both the catalysts electivity in DPO and its stability over 20h of time-on-stream.The characterization results show that La_2O_3 species interact strongly with silver particles on the silica surface which result in significant improvement in the dispersion profile of silver and marked decrease in the size of silver nanoparticles(AgNPs). The estimated mean diameter of AgNPs is ca. 4.0 nm in Na/Ag/Mo/5 wt%La_2O_3-SiO_2, which is smaller than that(53.9 nm) found in Na/Ag/SiO_2. The presence of subnanometer AgNPs on Ag/La_2O_3-SiO_2 prior addition of MoO_3 and NaCl to the sample can enhance the mutual electronic synergism between Ag, MoO_3 and Na for selective production of propylene oxide.     

CaCl2-NaCl熔盐中La2O3电脱氧反应的电化学研究

采用熔盐电解法研究了La2O3电脱氧反应过程。由电位阶越实验及取样电流电位分析和对电解产物进行X衍射分析表明La2O3的电脱氧反应是可以进行的，La2O3得电子还原为低价脱氧产物LaO，接着LaO作为中间产物与阳极气体Cl结合生成氯氧镧。     

CdS/Eu~(3+)-TiO_2复合光催化剂制备及性能研究

用溶胶-凝胶法制备了复合光催化剂CdS/TiO2和CdS/Eu3+-TiO2。利用XRD、UV-Vis漫反射光谱对样品进行了表征。以可见光分解水制氢为探针反应考察了催化剂的活性。结果发现Eu3+掺杂TiO2后抑制了TiO2晶粒生长,提高了光生电子和空穴的分离,从而提高了复合光催化剂的活性。     

Y2O3和La2O3对金属陶瓷内衬显微硬度和耐蚀性的影响

研究了钇、镧等添加物对金属陶瓷内衬显微硬度和耐蚀性的影响。结果表明:加入Y2O3、L a2O3和S iO2可使陶瓷层的孔隙度降低,一定程度上使耐蚀性增加。L a2O3对提高陶瓷层性能的效果比Y2O3要好。     

稀土钼杂多配合物催化合成尿囊素的研究

合成制备了稀土钼杂多配合物K11[Y(PMo11O39)2],并以之作为催化剂,双氧水为氧化剂,乙二醛和尿素为原料合成尿囊素。探讨研究了催化剂量、反应温度、反应时间及n(C2H2O2)∶n(H2O2)对尿囊素收率的影响。得到了适宜的合成条件为:n(C2H2O2)∶n(H2O2)=1.0∶1.1,氧化反应温度约为5℃~8℃,尿囊素生成温度约为75℃~80℃,反应时间7小时,在该条件下尿囊素的收率可达28.75%。     

Rare earths (Ce,Y, Pr) modified Pd/La_2O_3-ZrO_2-Al_2O_3 catalysts used in lean-burn natural gas fueled vehicles

14%REO_x-2.5%La_2 O_3-33.5%ZrO_2-50%Al_2 O_3(RE = Ce, Y, Pr) composites were prepared by a coprecipitation method. The Pd catalysts were obtained by an aqueous solution of Pd(NO_3)_2 loaded on the rare earths modified composites with an initial wet impregnated method. The experiment results show that catalytic activity of the rare earths modified Pd/La_2 O_3-ZrO_2-Al_2 O_3 catalysts is better than bare sample for methane oxidation. The structural characterization results reveal that the rare earths modified Pd catalysts increase amounts of surface active oxygen species by X-ray photoelectron spectroscopy(XPS) analysis and improve the dispersion of active component from H2-temperature programmed reduction(H2-TPR) measurement compared with bare sample. Especially,Pd/14%Y_2 O_3-2.5%La_2 O_3-33.5%ZrO_2-50%Al_2 O_3 sample exhibits highly active stability, it is related to the Pd particles highly dispersion,which was observed by transmission electron microscope(TEM) images.     

Photocatalystic Oxidation Degradation of Polyethylene by Nano-TiO_2 Doped Rare Earth Ion

Photocatalystic Oxidation Degradation of Polyethylene by Nano-TiO_2 Doped Rare Earth Ion     

稀土杂多酸盐催化环己酮氧化合成己二酸

合成一系列稀土杂多酸盐,考察了其在环己酮氧化合成己二酸反应中的活性.结果表明,K_8H_3[La(PW_(11)O_(39_)_2]·25H_2O在环己酮氧化合成己二酸的过程中显示了较高的催化活性,反应8h,己二酸的收率可达71.9%.考察了温度,时间,反应物加入量,过氧化氢加入量,催化剂加入量等一系列条件对反应的影响,确定了最佳反应条件.     

Enhancing mechanical properties and air permeability of corundum porous materials by in situ formation of LaAl_(11)O_(18) in bonding phase

Corundum porous materials of particle-packing type with different contents of in situ formed LaAl_(11)O_(18)were prepared using tabular corundum,reactive alumina and La_2O_3 powder as raw materials.The effects of the introduction of LaAl_(11)O_(18) on the microstructure.phase composition and properties of the porous materials were investigated.The specimens were characterized by scanning electron microscopy.X-ray diffraction and mercury porosimetry.Results show that platelet-like LaAl_(11)O_(18) is formed in situ by the reactions of La_2O_3 and Al_2O_3.With a certain amount of La_2O_3 added.the cold crushing strength,cold modulus of rupture and hot modulus of rupture(1400 x 0.5 h) of the specimens are increased,and the air permeability is improved simultaneously.However.upon further increasing the amount of La_2O_3 added,the mechanical properties and air permeability of the porous materials then decrease gradually owing to the increased numbers of pores and cracks in the bonding phase.The enhanced mechanical properties of the specimens with La_2O_3 added are attributed to the strengthening effects of plate-like LaAl_(11)O_(18) in the bonding phase and to the activated sintering of both Al_2O_3 powder and corundum coarse aggregate for the diffusion of La~(3+)in Al_2O_3 lattice.In addition,the improved air permeability of the specimens should be related to the decreased content of pores in the bonding phase and the reduced number of interfacial cracks.     

化学法测定碳氮化钛中氮含量

采用正交设计优化法研究了硫酸 焦硫酸钾湿法熔融(化学法)分解碳氮化钛,以较少的实验次数确定了蒸馏分离和试样分解的最佳分析条件,通过条件实验,建立了相应的分析方法,测定结果与惰气熔融热导法一致。     

Phase equilibria in low basicity region of CaO-SiO_2-Nb_2O_5-(5 wt%,10 wt%,15 wt%) La_2O_3 system

The lack of thermodynamic information,such as primary phase fields and liquidus temperatures,in the CaO-SiO_2-Nb_2O_5-La_2O_3 quaternary system phase diagram has restricted the comprehensive utilization of the niobium(Nb) and rare earth(RE) resources.In this work,the phase equilibria in low basicity region(w(CaO)/w(SiO_2)1) of CaO-SiO_2-Nb_2O_5-(0-15 wt%)La_2O_3 system at 1373-1873 K were experimentally studied by thermodynamic equilibrium experiment,and then,the results were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).Additionally,an optimized method was proposed to process the compositions of equilibrium liquid phases at different temperatures.According to the experimental results,the univariate line between CaNb_2O_6,SiO_2 and LaNbO_4 primary phase fields,interface between CaNb_2O_6 and SiO_2 primary phase fields and isothermal liquidus surfaces in SiO_2 primary phase field were determined.Finally,the spatial phase diagram of CaO-SiO_2-Nb_2O_5-La_2O_3 within specific region was constructed,and furthermore,the phase diagram was also presented in CaO-SiO_2-Nb_2O_5 pseudo-ternary system with w(La_2O_3)=5 wt%,10 wt% and 15 wt%.The research results have guiding significance for the improvement of related phase diagram and the comprehensive utilization of Nb and RE resources.     

Kinetic modeling of titania reduction by a methane-hydrogen-argon gas mixture

This article describes kinetic modeling of titania reduction and carburization by methane-containing gas, based on experimental data reported previously by Zhang and Ostrovski. A sequence of titania reduction to titanium oxycarbide,

A Study on La_2O_3-Y_2O_3-Mo Secondary Emission Material

Thephenomena ,mechanismandtheapplicationofsecondaryemissionofmanykindsofmaterialshavebeenstudiedsincethesecondaryemissionphenomenawasdiscoveredbyCompellin 1899.Withthedevel opmentofelectronictechnologythephenomenaofsec ondaryemissionhavebeenincreasinglyappliedinmanyfields[1,2 ] ,especiallyinhighpowermagnetrontube .Nowadays ,thecathodesofhighpowermag netrontubeusedinthefieldsofbroadcast,correspon denceandnationaldefensearemainlyBa Wcath odes[3] andsomeTh Wcathodes .However ,Ba Wcathodeishard…