稀土复合氧化物燃烧催化剂的性能及表征

浸渍法制备了稀土型燃烧催化剂 ,采用多晶 X射线衍射 (XRD)、程序升温还原 (TPR)、差热热重分析(DTA- TG)、X射线光电子能谱 (XPS)和二甲苯催化氧化活性测试等方法表征了该燃烧催化剂的结构和性能     

LnSrCoO4稀土复合催化材料制备与表征

首次采用聚乙二醇凝胶法制备了Co系类钙钛矿LnSrCoO4(Ln=La,Pr,Nd,Sm,Eu) 复合氧化物,研究了稀土对催化剂的结构和催化性能的影响,考察了它们对 CO和C3H8 的氧化反应活性,并运用XRD、BET、TPD等方法对催化剂进行了表征.结果表明该类复合氧化物具有K2NiF4结构,它们的结构和催化性能随稀土不同而变化,其中以LaSrCoO4催化活性最好,这是由LaSrCoO4的晶格氧更易移动、Co3+离子含量更高,氧空位和反应时化学吸附氧更多所致.     

纳米复合粉末的结构和形貌表征

采用X射线衍射（XRD）方法重点对不同批次的ITO、ZrO2纳米复合粉末的相结构、晶粒平均尺寸进行了测定，并采用扫描探针显微镜（SPM）对ITO纳米复合粉末的形貌、粒度分布分别进行了观察和测定，采用透射电镜（TEM）观察了ZrO2纳米复合粉末的形貌，结果表明，多种方法相结合可对纳米复合粉末的微观结构参数进行全面的评估。     

钢铁材料复合夹杂物的聚焦离子束定位加工及结构表征

钢铁材料复合夹杂物的检测与表征,需要解决样品制备和微区相鉴定的难题。实验主要利用聚焦离子束精确定位功能,定位制备出复合夹杂物的透射电镜剖面样品,最大限度的呈现整个夹杂物的多种物相形态,再结合能谱仪的面分析功能和透射电镜的晶体结构分析技术对复合夹杂物进行全面的表征。通过对夹杂物的成分分析和物相衍射花样的标定,最终得到复合夹杂物的物相组成。结果表明,所分析复合夹杂物的形态和组成非常复杂,包括晶态的Mn₂TiO₄相、MgAl₂O₄相、Mn_0.33Zr_0.33Ti_0.33O_1.67相和非晶态的Ca-Al硅酸盐相。     

CeO2-SiO2复合氧化物的制备及性能表征

化学沉淀法制备了SiO2和CeO2以及复合氧化物CeO2-SiO2等纳米粉体。对粉体的形貌及物相结构、粒径大小通过TEM及XRD进行了检测分析。SiO2粉体为无定形结构,粒径约500 nm,立方萤石型结构的CeO2及复合氧化物CeO2-SiO2的平均粒径小于10 nm,说明复合氧化物的合成过程抑制了粒径的长大。制备了SiO2/CeO2质量比分别为5%、10%、15%、20%的复合氧化物,煅烧温度为400℃～1000℃,结果显示随着SiO2比例的增加,CeO2的特征峰在逐渐减弱,半高宽变宽,粒径变小;随着煅烧温度的升高,特征峰强度增加,半高宽变窄,颗粒的晶型发育越来越完善,但样品的粒径变大。     

新型钙钛矿结构复合氧化物材料的电导性能

研究了几种钙钛矿结构以及类钙钛矿结构材料的电导性能.实验表明,La_0.8Sr_0.2MnO₃, La_0.8Sr_0.2Ni_0.1Mn_0.9O₃,La_0.8Sr_0.2Ce_0.1Mn_0.9O₃和SrFe_0.5Co_0.5O₃电导率相差不大,均为10^-1S·cm^-1数量级;高温熔盐中耐侵蚀性能优良的LaLiMnO_y和LaLi_0.5MnO_y电导率差别很大,前者电导率大于1 S·cm^-1,达到了MCFC阴极对材料电导性能要求,而后者仅为10^-2S·cm^-1数量级.高达0.191 eV的电导激活能可能是LaLi_0.5MnO_y电导率过低的原因.     

Ti/Ce复合氧化物的制备及改性研究

采用燃烧法制备单体氧化物,异相成核沉淀法制备Ti/Ce复合氧化物并对其进行改性.采用XRD、IR、UV-vis、SEM对Ti/Ce复合氧化物进行了表征.对制备的样品进行改性研究,考察了改性剂类型、改性温度、酸度、改性剂用量等条件对改性效果的影响,得出改性工艺的最佳条件.对于CeO2/TiO2:改性剂选择钛酸酯偶联剂,温度45℃,时间60min,pH值为7,改性剂用量为5％(质量分数).TiO2/CeO2:改性剂选择钛酸酯偶联剂,温度55°C,时间60min,pH值为6,改性剂用量为5％.改性后可增强样品在基体中的可溶性,扩大其适用范围.     

Ti/Ce复合氧化物的制备与光催化研究

采用异相成核-沉淀法制备Ti/Ce复合氧化物。燃烧法制得的氧化铈和氧化钛与沉淀法制得的碳酸钛和碳酸铈进行复合。经煅烧制得Ti/Ce复合氧化物,所制样品用XRD、IR、UV-vis、SEM进行了表征。用上述制备的复合氧化物进行光催化实验,考察了催化剂的用量,溶液的酸度,双氧水的加入量,离心机的转数,催化时间对光催化效果的影响,得出最佳光催化条件:TiO2/CeO2复合氧化物光催化条件为pH=8,催化剂用量1 g/L,1000 r/min,不加双氧水,240 min光催化完毕;CeO2/TiO2复合氧化物催化条件为pH=9,催化剂用量2 g/L,1500 r/min,不加双氧水,300min光催化完毕。     

尖晶石型Co0.7Ce0.3Co2O4催化剂的制备及其甲烷催化燃烧性能的研究

采用共沉淀法、溶胶凝胶法和溶液燃烧法制备了一系列Co0.7Ce0.3Co2O4催化剂,研究了制备办法对催化剂甲烷催化燃烧反应性能的影响,并运用XRD、BET和TPR等技术对催化剂进行了表征.结果表明,共沉淀法制备的Co0.7Ce0.3Co2O4催化剂有较好的催化活性和热稳定性,与溶胶凝胶法和溶液燃烧法制备的Co0.7Ce0.3Co2O4催化剂相比,共沉淀法制备的Co0.7Ce0.3Co2O4催化剂有较高的晶格畸变率和比表面积、较大的孔径和孔容、较小的品粒度、较强的氧活动性和较低的甲烷催化燃烧反应的表观活化能.     

Structure and Catalytic Behavior of CuO-ZrO-CeO2 Mixed Oxides

The effect of doping CuO on the structure and properties of zirconia-ceria mixed oxide was studied. The results show that addition of CuO decreases the reduction temperature of ceria, and stabilizes the cubic structure of mixed oxides, and enhances catalytic activity of CuO-ZrO-CeO2 mixed oxides for CO oxidation. Increasing ceria content in the mixed oxides can enhance the catalytic activity, but some impurities such as sulfate make catalytic activity falling. There is little effect of calcination temperature on catalytic activities, implying that these catalysts are effective with good thermal stability.     

Preparation, Characterization and Catalytic Performance of Nanometer Ceria-Zirconia Solid Solution

Ce0.6Zr0.4O2 solid solution was prepared by co-precipitation technique using hydrazine hydrate as precipitator.Various physico-chemical techniques such as XRD, FT-Raman, SEM, TEM, etc.were used to characterize the resultant powder.Meanwhile, its catalytic activity was evaluated in the synthesis of n-butyl acetate by the reaction of acetic acid and n-butyl alcohol.The results show that ceria-zirconia solid solution forms single cubic structure and its particle diameter is less than 100 nm.As a sort of solid acid, it possesses high catalytic activity and can be easily separated from reaction liquid.After it is used for ten times, its activity basically kees unchanging.     

Characterization and CO Catalytic Oxidation of CuO／Ce-Zr-La-O Catalyst

The Ce-Zr-La-O solid solution was prepared by the sol - gel method. The structure and the redox behavior of Ce-Zr-La-O solid solution and CuO/Ce-Zr-La-O catalysts were investigated by using XRD, Raman and TPR techniques. The result shows that the reduction capability of Ce0.7Zr0.3-y LayO solid solution is related to content of La. Appropriate content of La can enhance the redox capability of the solid solution. The oxidation activity of the CuO (6%)/Ce0.7Zr0.15La0. 15O catalyst is the highest. CuO, which finely dispersed and interacted with the support, is the site of oxidation activity.     

Oxides Catalysts of Rare Earth and Transient Metal for Catalytic Oxidation of Benzene

The catalysts of CeO2 and the mixture of CeO2 and CuO were prepared, and the activities of these catalysts for completely oxidizing benzene were studied.The results show that the optimal proportion of CeO2/CuO is 6: 4.The highest temperature at which benzene was completely oxidized on these catalysts at different airspeed was measured.Compared these catalysts with the noble metal used, our catalysts had superiority in the resources and the industrial cost besides good activities.     

Catalytic Performance of Ce／Zr Oxides Catalysts for Soot Combustion

Catalytic performances of a series Ce/Zr oxides(CexZr1-xO2 )for soot combustion were investigated. The catalytic activities for soot combustion were affected by both the Ce/Zr ratio and the oxygen storageinvestigated. Thecapability of Ce/Zr oxides. O2-TPD and TG-DTA results indicate that CexZr1-xO2 can release its lattice oxygen continuously and promote soot combustion even no oxygen occurs in the reaction atmosphere. Among these Ce/Zr oxides, Ce0.5Zr0.5O2 has the best catalytic activity, and the ignition temperature of soot combustion was about 410℃, which is close to the practical exhaust temperature of the diesel engine.     

Effect of RE Oxide on Impact Toughness and Primary Structure of Surfacing Metal

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制备因素对PrSrCoO4催化剂的结构及催化活性的影响

采用共沉淀法、柠檬酸络合法和聚乙二醇凝胶法制备了PrSrCoO4催化剂,以CO和C3H8氧化为探针反应及XRD、XPS、TPD、TPR和BET等实验手段对催化剂进行了考察.结果表明,所有样品都具有K2NiF4型结构,不同方法制得的复合氧化物呈现不同的催化活性,聚乙二醇凝胶的焙烧温度对催化剂的结构和催化活性有较大影响.     

Effects of Transition Metal Oxides on Thermal Conductivity of Mould Fluxes

The thermal conductivity of the mould fluxes containing transition metal oxides was measured by hotline method at different temperatures. The relationship between the thermal conductivity of mold fluxes and the contents of transition metal oxides was discussed. The synthetic slags were composed of 30.0% — 35.4% CaO, 34.7% — 38.6% SiO₂, 6% Al₂O₃, 9% Na₂O, 14.4% CaF₂, 0–4% Cr₂O₃ and 0–8% MnO in mass percent. The results indicated that Cr₂O₃ and MnO had a negative effect on thermal conductivity of mold fluxes. The thermal conductivity of mold fluxes was about 0.25 — 0.55 W/(m K) when the temperature reached 1300 °C, and it increased sharply to about 1.32–1.99 W/(m K) when the temperature reduced from 1300 to 1000 °C. The thermal conductivity of mold fluxes containing Cr₂O₃ and MnO was 10%—25% lower than those of original fluxes. The decrease in thermal conductivity was attributed to the change of molecular structure of mold fluxes. In addition, the poor integrity and regulation of polycrystal structure, complexity of crystal structure, and effects of impurities in the boundary and lattice distortion leaded to the reduction in the thermal conductivity. Na₂CrO₄, Mn₂SiO₄ and other minor phases were also found in the samples containing Cr₂O₃ and MnO, respectively.     

混凝与电絮凝废水中多种金属离子协同沉淀机制研究

采用混凝和电絮凝工艺去除废水中的多种金属离子(Pb^2+、Cd^2+、Cu^2+、Ni^2+),研究混凝反应主要影响因素液相pH、混凝剂(PAC)投加量对各金属离子去除效率的影响,探讨废水pH、施加电流密度对各金属离子电絮凝去除效率的影响,阐明混凝和电絮凝多金属协同沉淀去除的机制。结果表明,PAC混凝去除废水中Pb^2+、Cd^2+、Cu^2+、Ni^2+的最佳pH为7.0,最佳投加量600mg/L,Pb^2+、Cu^2+去除效率远高于Cd2+、Ni2+;电絮凝反应金属离子去除的最佳pH为7.0,最佳电流密度为1.2~1.8mA/cm^2。混凝与电絮凝金属离子的去除效率与金属离子的半径、相对分子质量大小无关,而与金属离子的溶度积直接相关,金属离子的溶度积越低,混凝和电絮凝去除效率越高。电絮凝较混凝反应具有更高的金属离子去除效率。研究结果对于采用混凝和电絮凝工艺处理多金属污染废水具有借鉴和指导意义。