Preparation of High-Surface Area Nano-CeO2 by Template-Assisted Precipitation Method

The high-surface area nano-CeO2 was prepared by Ce（NO3）3 by precipitation method, with surfactant cetyhrimethyl ammonium bromide （CTAB） as templating agent. The effects of the precipitating agents, reaction temperature, ageing time, and calcination temperature on the surface area, as well as the pore structure and the mean crystallite size of nano-CeO2 were studied. It was found that the reaction of Ce（NO3）3 with NaOH in the presence of CTAB at 90℃ for 12 h yieldsed a cerium oxide/surfaetant mixture, which after calcination at 400℃ resulted in high-surface area nano-CeO2. The mean crystallite size of CeO2 was approximately 6 nm, surface area was in excess of 200 m^2· g ^- 1, pore size was approximately 9 nm, and the pore distribution was concentrative. Moreover, the surface area can still reach 147 m^2·g^- 1 after calcination at 700 ℃, which showed the good thermal stability of the CeO2. The number of oxygen vacancies in the structure of CeO2 corresponded with the surface area of CeO2, and the high surface area was propitious to the formalion of oxygen vacancies.     

Effect of Preparation Method on Surface Area and Crystalline Form of CeO2-ZrO2 Solid Solution

TheCeO2 ZrO2 solidsolutionisacrucialcompo nentinthethree waycatalysts(TWCs)usedtocatalyzethesimultaneouspurificationofCO ,HCandNOxfromanautomobileexhaust [1～ 3] .Besidesafeasiblecatalyticactivity ,itshouldhavehighthermalstabilityandoxygenstoragecapacity(OSC) .InordertogainhighperformanceCeO2 ZrO2 solidsolution ,varioustechniqueshavebeendeveloped .ItwasshownthataneffectofpreparationmethodonthesurfaceareaandcrystallineformofCeO2 ZrO2 isveryobvious .Intheearliestwork ,theCeO2 ZrO…     

乙二醇辅助聚乙烯醇制备花状氧化铈探索

利用浓硝酸和双氧水将不规则形貌氧化铈溶解，生成硝酸铈.采用水作为溶剂或水和乙二醇共同作为溶剂，聚乙烯醇作为分散剂，草酸铵作为沉淀剂，通过直接沉淀法合成草酸铈前驱体，在高温反应炉中按照8 ℃/min的升温程序，600 ℃保温2 h，得到氧化铈.结果表明，以水为溶剂，聚乙烯醇为分散剂时，所得氧化铈易碎，呈尺寸不均匀片状，厚度在100 nm左右，长度和宽度尺寸约3~10 μm和1~2 μm，比表面积为14.9 m2/g.以水和乙二醇共同为溶剂，聚乙烯醇为分散剂时，所得氧化铈具有花状结构，由表面光滑、尺寸均匀的纳米片组成，片状氧化铈的厚度、长度和宽度分别约100 nm、4 μm和1.5 μm，形成直径约2~5 μm的氧化铈花状团簇，比表面积为21.45 m2/g.利用乙二醇辅助聚乙烯醇制备花状氧化铈，有望应用于调节具有花状形貌的稀土氧化物.      

Synthesis and Characterization of Y-Doped Mesoporous CeO2 Using A Chemical Precipitation Method

Using cetyltrimethylammonium bromide （CTAB） as the template agent, cerium nitrate as the cerium resource, yttrium nitrate as the yttrium resource, and ammonium carbonate as the precipitating agent, mesoporous CeO2 powders doped with different yttrium contents were successfully synthesized using a chemical precipitation method, under an alkalescent condition. Properties of the obtained samples were characterized and analyzed with X-ray diffraction （XRD）, energy dispersive analysis of X-rays （EDAX）, transmission electron microscopy （TEM）, infrared （IR） absorbance, and the BET method. For the prepared samples with 20% （molar ratio） Y-doped content, a BET specific surface area of 106. 6 m^2 · g^- 1, with an average pore size of3~27 nm were obtained. XRD patterns showed that the doped samples were with a cubic fluorite structure. TEM micrographs revealed that the doped samples showed a spherical morphology with a diameter ranging from 20 to 30 nm and a round pore shape. IR results indicated that the Ce-O-Ce vibration intensity decreased as the Y-doped content increased. N2 adsorption-desorption isotherms showed that the samples possessed typical mesopore characteristics. The average pore size of the samples decreased alter mesoporous CeO2 was doped with yttrium, and the average pore size decreased largely as the Y-doped content increased.     

大比表面积、大粒度氧化铈制备工艺研究

氧化铈是一种廉价而用途极广的新型功能材料,随着功能材料的不断发展,各种特殊物理性能的氧化铈的合成和性能越来越受到大家的关注。以氯化铈溶液为原料,加入一定量含肼盐添加剂,以草酸为沉淀剂,硝酸和草酸混合溶液对草酸铈沉淀进行浸泡或淋洗,结合缓慢升温灼烧,可以获得大比表面积、大粒度氧化铈,满足了客户需求。     

Study on the preparation process of large particle cerium oxide

The large particle cerium oxide was prepared using oxalic acid as precipitation agent. The effects of preparation conditions on the particle size of cerium oxide were discussed. The results showed that the particle size of cerium oxide could be controlled effectively by the temperature,acidity of the solution,aging time,etc. The optimized preparation process of large particle cerium oxide was obtained. The cerium oxide with size between 50 μm to 150 μm was prepared by the process. Moreover,the cerium oxide particles were dispersed uniformly.     

Synthesis and Characterization of Large Surface Area Yttrium Oxide by Precipitation Method

Rareearthoxides(REO)withlargesurfaceareahavehighchemicalreactionactivity ,soitisusedwidelyinthefieldofcatalysis ,SOFC ,advancedce ramicandsoon[1] .Inordertosatisfythedemandofthenewfunctionmaterials ,thepreparationmethodofspecialphysicalpropertyREcompoundneedstobedeveloped .Yttriumoxide ,especiallywithlargesur faceareaisaREOandwidelyusedintheabovefield .Industrially ,yttriumoxideusuallywaspreparedbythermaldecompositionofyttriumoxalateat 80 0～10 0 0℃for 2h .Itssurfaceareaisonly 2～ 4m2 ·…     

Study on the preparation process of large particle cerium oxide

The large particle cerium oxide was prepared using oxalic acid as precipitation agent. The effects of preparation conditions on the particle size of cerium oxide were discussed. The results showed that the particle size of cerium oxide could be controlled effectively by the temperature, acidity of the solution, aging time, etc. The optimized preparation process of large particle cerium oxide was obtained. The cerium oxide with size between 50 μm to 150 μm was prepared by the process. Moreover, the cerium oxide particles were dispersed uniformly.     

Surface and Texture Properties of Tb-Doped Ceria-Zirconia Solid Solution Prepared by Sol-Gel Method

The three-way catalysts （TWCs） promoters Ce0.6Zr0.4- x TbxO2-y were prepared by sol-gel method. BET surface areas analysis indicated that an increase of the dopant Tb content from x = 0.05 to x = 0.15 favors an increase of surface area from 66.8 to 80.4 m^2· g^-1 compared with the undoped sample Ce0 .6oZr0.40O2 65.1 m^2·g^- 1 after calcination at 650℃. Transmission electron microscopy （TEM） observation indicated that the doped samples have a higher thermal stability. The XRD and Raman spectra confirmed that the Ce0.6Zr0.4-xTbxO2-y cubic solid solution is formed. XPS analysis revealed that Ce and Tb mainly existed in the form of Ce^4＋ and Tb^3 ＋ , and Zr existed in the form of Zr^4＋ on the surface of the samples. The doped samples were homogenous in composition ; the introduction of Tb into the CeO2-ZrO2 promoters resuited in the formation of a solid solution, and the concentration of surface lattice oxygen was increased.     

盐酸改性对天然斜发沸石孔道特征、成分、表面电位及阳离子交换性能的影响

采用不同浓度盐酸对天然斜发沸石进行改性,并系统地研究了改性沸石的孔道特征、化学成分、表面电位及阳离子交换性能的变化.盐酸改性后,沸石晶体结构破坏较小,表面变得疏松粗糙,K+、Na+、Ca2+和Mg2+元素含量均小幅下降;表面负电荷增加,阳离子交换容量减小;比表面积和总孔体积均有所提高,最高分别从原沸石的35.97 m2·g-1和0.0761 m3·g-1提高至64.46 m2·g-1和0.1156 m3·g-1.盐酸改性对沸石微孔、介孔和大孔的分布影响明显.从迟滞回线形状判断沸石孔道类型均为不均匀狭缝型孔道,盐酸改性不会改变沸石孔道类型.      

钙处理对成品无取向硅钢夹杂物特性的影响

通过取样检测结合热力学计算,分析了钙处理对成品无取向硅钢中夹杂物特征及硫化物夹杂的析出机制的影响。结果表明,钢中尺寸大于3μm的有害夹杂物主要是AlN、MgO-SiO2、CaO-Al2O3-SiO2类复合夹杂物及其与MgS、MnS、CaS的复合析出物。钙处理钢中没有检测到单独的Al2O3、SiO2及铝酸钙类夹杂物。钙处理钢中形成的液态3CaO·Al2O3、MgO·SiO2和Al2O3夹杂物被精炼渣吸收,改性去除了钢中大尺寸Al2O3夹杂物。钙处理钢中尺寸大于3μm的氧化物夹杂主要是含CaO和(或)CaS的Al2O3-SiO2类夹杂。硫化物在MgO-SiO2类氧化物表面的析出有利于其形貌趋于规则。钢中不同形貌的AlN夹杂物呈多尺度分布,钙处理对大尺寸AlN的析出特性影响不大。氧硫化物及其与AlN复合析出并定向长大的过程,与其晶体结构有关。氧化物夹杂的硫容量决定了其与硫复合的难易程度。钙处理钢中CaS在氧化物表面呈局部包裹析出和局部吸附析出。     

Synthesis and characterization of carbon-TiO_2-CeO_2 composites and their applications in phenol degradation

The objective of this work was to synthesize particles of titanium oxide and cerium oxide supported on carbon, which was obtained through the pyrolysis of orange peel. The materials were characterized using scanning electron microscopy, X-ray diffraction, infrared spectroscopy, and the specific surface area from Brunauer-Emmett-Teller method. The photocatalytic properties of the synthesized materials were determined by the degradation of phenol in 30 mg/L aqueous solutions. TiO_2-CeO_2 particles were obtained with an average spherical size of 57 nm and were supported on the carbon surface; this material presented a specific surface area of 296 m2/g and degrades ~40% of phenol after 240 min of UV irradiation.     

氧化铝赤泥盐酸浸出稀土元素研究

在用盐酸浸出氧化铝赤泥提取氧化钪的过程中,稀土元素镧,铈,钕也一同浸出,进入到浸出液中。研究了拜耳法赤泥盐酸浸出稀土元素镧,铈,钕的过程。研究了浸出温度、酸度、液固比和浸出时间对稀土元素浸出率的影响。研究结果表明,影响稀土浸出率的因素依次是浸出温度,盐酸浓度,配料液固比,和浸出时间。当接近沸点109℃浸出时,镧、铈、钕浸出率提高最快。盐酸酸度在4～5 mol.L-1时,浸出率升高较快,5～7 mol.L-1时,缓慢提高,当超过7 mol.L-1时,镧、铈、钕的浸出率基本不变化。当液固比为4.0时,镧、铈、钕元素的浸出率较低,仅为60%～75%之间,当液固比提高到5.0时,稀土元素的浸出率升高较快。随着浸出时间的延长,氧化稀土的浸出率从60～180 min时,缓慢提高,在180 min时达到最大值,超过180 min后,变化不大。在温度为沸点(109℃),液固比6.0,时间180 min。盐酸浓度7 mol.L-1的条件下浸出,赤泥中La,Ce,Nd的浸出率能达到95%以上。     

Preparation and Characterization of CeO2-ZrO2 Solid Solution Ultrafine Particles Using Reversed Microemulsion

The development of the TWCs (three-way cata-lysts) was dictated bythe need to si multaneously con-vert the three main pollutants inthe exhaust gases ,i .e .,hydrocarbons (HCs) ,COand NOxpresent in theautomotive exhaust to H2O, CO2and N2[1]. Highestconvers…     

Novel Salt-Assisted Combustion Synthesis of High Surface Area Ceria Nanopowders by An Ethylene Glycol-Nitrate Combustion Process

Ceria and ceria-based powders are candidate ma-terials for a wide range of applications ,for example ,solid electrolytes for solid oxide fuel cells (SOFC)[1],three way catalysts for the treatment of automotive ex-haust gases[2],petroleum-cracking catalyst[3],oxygensensors[4], chemical-mechanical polishing for micro-electronics[5],and UVfilter[6].In recent years , since high surface area ceriananoparticles show superior physical and chemicalproperties to bulk particles , much effort has been …     

氧化锌烟尘浸出过程硅-锗沉淀高效分散解聚研究

在高新技术对锗需求日益增长的背景下,基于对烟尘浸出渣中锗赋存状态的考察,查明了硅锗聚合沉淀机制,及超声诱导锗硅沉淀高效分散解聚机制。采用相关性分析等首次为锗硅聚合沉淀猜想提供实质性证据,Ge-Si相关性系数k为66.57,相关性拟合度R²高达97.99%。在含锗氧化锌烟尘浸出过程中,溶液中硅离子会聚合形成硅酸胶体吸附溶液中的锗,引起锗损失14.81%,造成锗工业回收率低。超声引入浸出过程后,会在溶液中会产生空化气泡,发生空化作用,空化气泡破裂时释放的能量形成局部的高温高压并产生冲击波与微射流,会持续不断冲击聚硅酸胶体表面,使得聚硅酸胶体比表面积增大58.19%,孔径增大666.32%,孔容增大165.79%,使得大颗粒的硅胶解聚为小颗粒的低聚硅酸,降低硅胶对锗的吸附,超声条件下锗损失降低了59.35%。研究建立的氧化锌烟尘浸出过程硅-锗沉淀高效分散解聚,可有效实现氧化锌烟尘中锗高效回收。     

碳酸氢铵沉淀法制备氧化铈抛光粉

利用碳酸氢铵做沉淀剂制备氧化铈抛光粉,通过L16(44)正交试验,研究了温度、硝酸铈浓度、滴加速度和搅拌速度对氧化铈粒度和比表面积的影响。得到的最佳粒度制备工艺条件为:温度60℃、硝酸铈浓度50g/L、搅拌速率500r/min、滴加速度50mL/min。并对最佳制备工艺条件下制取的抛光粉进行粒度、形貌和抛蚀量进行研究。     

烧结温度对锂离子电池负极材料Li4Ti5O12性能的影响

采用钛酸四丁酯为钛源、一水合氢氧化锂为锂源,利用水热法制备锂离子电池负极材料Li₄Ti₅O₁₂（LTO）,研究了水热后不同烧结温度对LTO相组成、微观形貌及电化学性能的影响。结果表明:当煅烧温度分别为500、550、600、650、700℃时,烧结LTO均为尖晶石型;500、550、600℃烧结LTO的微观形貌为纳米片状结构,当温度升高到650℃时,LTO出现纳米棒状结构,随着温度继续升高,LTO在700℃时生成较厚的纳米片状结构;当烧结温度为650℃时,LTO的比表面积为94.5907 m2·g-1,气孔体积为0.9663 mL·g-1,此时Li₄Ti₅O₁₂的放电比容量达到最大值240 mAh·g-1;电流密度100 mA·g-1、循环260次条件下,LTO容量保持率达96.45%,电流密度为1和2 A·g-1、循环1000次条件下,LTO容量保持率达92.97%和77.21%。     

Sol-Gel Synthesis and Luminescent Characteristic of Doped Eu^3 ＋ Silicate-Silica Phosphor

Silicagelphosphorsdopedrareearthionshave attractedgreatattentionofmanyresearchersdueto theseadvantages,suchashighersamplehomogeneity,purityandstable,efficientandenvironmentallyfriend lyphotoluminescencematrixmaterials,whichisless toxicleadtonetconversione…     

Preparation of Well Dispersed and Ultra-Fine Ce （Zr）O2 Mixed Oxide by Mechanochemical Processing

Ultra-fine CeO2-ZrO2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce2(CO3)3·8H2O, ZrOCl2·xH2O and ammonia were used as reactants. It is found that the crystalline Ce2(CO3)3·8H2O and ZrOCl2·xH2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce0.15Zr0.85O2 mixed oxide with pure tetragonal phase structure and medium particle size(D50)less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.