铽掺杂铈锆固溶体的合成及结构表征

采用溶胶-凝胶法制备了不同比例Tb掺杂的三效催化剂促进剂Ce0.6Zr0.4-xTbxO2-y(x=0.05、0.10、0.15).BET比表面积分析表明,随着Tb的掺杂量由x=0.05递增到x=0.15,在650℃焙烧的样品其比表面积由66.8增加到80.4m2/g,而未掺杂样品Ce0.6Zr0.4O2的比表面积为65.1m2/g.X射线衍射和拉曼光谱证实形成的固溶体为萤石型立方相结构.X光电子能谱分析表明,固溶体表面Ce和Tb主要以Ce4 和Tb3 形式存在,Zr以Zr4 形式存在;掺杂样品组成均匀,Tb的掺入促进了固溶体的形成,增加了表面晶格氧的浓度.     

载体对铂基疏水催化剂活性的影响

为了研究载体对铂(Pt)基疏水催化剂活性的影响,分别选取了炭黑、SiC纳米粉、铈锆复合氧化物(Ce0.4Zr0.6O2-γ-Al2O3)等三种物质,在氯铂酸的乙二醇溶液中,用高压微波加热法制备了Pt基催化剂,然后将其与聚四氟乙烯一起负载于泡沫镍上,制成疏水催化剂.用X射线衍射、透射电子显微镜、X光电子能谱、扫描电子显微镜等方法分析了催化剂的结构与组成,并研究了疏水催化剂对氢-氧复合反应及氢-水交换反应的催化活性.结果表明:Pt在载体表面分布均匀,在Pt/C、Pt/SiC、Pt/Ce0.4Zr0.6O2-γ-Al2O3中Pt的平均粒径分别为4.46、1.67和1.77nm;Pt/C、Pt/SiC催化剂中Pt存在Pt(0)、Pt(Ⅱ)和Pt(Ⅳ)三种价态;Pt/C、Pt/SiC在泡沫镍表面的分布均匀,而Pt/Ce0.4Zr0.6O2-γ-Al2O3分布不均匀.Pt/C/FN对氢-氧复合反应和氢-水交换反应的催化活性都较高;Pt/SiC/FN和Pt/Ce0.4Zr0.6O2-γ-Al2O3/FN对氢-氧复合反应的催化活性高,但是对氢-水交换反应的催化活性很低.     

Ce0.6Zr0.35Pr0.05O2纳米固溶体的制备及性能研究

用共沉淀法制备出Ce0.6Zr0.35Pr0.05O2纳米固溶体,并利用TG-DTA-DTG、XRD、TEM和H2-TPR等方法对样品的物相结构、晶粒大小、还原性及高温热稳定性进行表征.结果表明,Ce0.6Zr0.35Pr0.05O2纳米固溶体为物相结构稳定的立方相固溶体,该粉体的平均粒度为10 nm左右,分散性好,而且与Ce0.6Zr0.4O2相比,在Ce0.6Zr0.35Pr0.05O2中,Pr的存在明显提高了其还原性和高温热稳定性.     

不同碱辅助的沉积沉淀法对三效催化剂稳定性的影响

老化处理会导致三效催化剂(TWCs)严重失活,因此提高催化剂的耐久性能是TWCs设计的目标.本工作采用不同碱辅助的沉积沉淀法,即尿素辅助沉积沉淀法和氨水辅助沉积沉淀法制备了Pt/Ce0.4Zr0.5La0.05Pr0.05O2(Pt/CZ)三效催化剂,分析了不同碱对催化剂物理化学性质、催化活性和耐久性的影响.结果表明,...     

储氧材料Ce0.6Zr0.4-xPrxO2-δ的性能及在三效催化剂中的应用

采用溶胶-凝胶法制备了系列三效催化剂储氧材料Ce0.6Zr0.4-xPrxO2-δ（x=0．05，0．10，0．15）。X射线衍射证实形成的固溶体为萤石型立方相结构；BET比表面积分析表明，随着Pr的掺杂量由x=0．05递增到工=0．15，在650℃焙烧的样品其比表面积由66．5增加到79.9m^2／g，而未掺杂样品Ce0．6Zr0.4O2的比表面积为65．1m^2，g；粒度分布及透射电镜分析发现，制备的固溶体在水相中存在着团聚现象。应用在含有Pt，Rh和Pd的三效催化剂的制备。催化活性测试表明，在铈锆氧化物储氧材料中掺杂少量Pr，可降低三效催化剂对CO、C3H6和NO的起燃温度。不论是在富燃区还是在贫燃区，所有掺杂Pr的三效催化剂对各气体的催化转化率均高于未掺杂Pr的三效催化剂。     

CeO2对RuO2/γ-Al2O3催化剂湿式氧化降解苯酚性能的影响

采用浸渍法制备了RuO2/γ-Al2O3和RuO2/CeO2/γ-Al2O3催化剂,并利用XRD、sEM和XPS对催化剂进行了表征,研究了Ce的加人对RuO2/γ-Al2O3催化剂表面分散性和催化剂表面元素Ru,O和Ce化学态的影响,同时考察了RuO2/γ-Al2O3和RuO2/CeO2/γ-Al2O3催化剂湿式氧化降解苯酚的活性,并深入探讨了Ce对RuO2/γ-Al2O3催化剂的助催化作用.结果表明:Ce掺杂改性后,使催化剂表面Ru的化学态降低、表面氧空位增加,并且活性组分Ru的分散性增加,从而使RuO2/CeO2/γ-Al2O3催化剂的活性提高,因此Ce起到了显著的助催化作用.     

固相化学法制备纳米Ce0.75Zr0.25O2粉体的表征及应用（英文）

以Ce2(CO)3,ZrOCl2.8 H2O和H2C2O4.2 H2O为原料,第一次成功地采用了机械力活化固相化学法制备纳米Ce0.75Zr0.25O2粉体。以XRD、TEM分析及XPS等测试手段对Ce0.75Zr0.25O2粉体的结构和形貌进行了表征,结果表明,产物为单一立方相的球形粉体,平均粒径小于20nm,比表面积为85.4m2/g。通过TG-DTA分析,对合成过程中可能发生的化学反应机理进行了分析。对Ce0.75Zr0.25O2氧化物固溶体在三效催化剂中的活性进行了评价。     

CeO2对RuO2／γ-A12O3催化剂湿式氧化降解苯酚性能的影响

采用浸渍法制备了RuO2／γ-A12O3和RuO2／CeO2／γ-A12O3催化剂，并利用XRD、SEM和XPS对催化剂进行了表征，研究了Ce的加入对RuO2／γ-A12O3催化剂表面分散性和催化剂表面元素Ru，O和Ce化学态的影响，同时考察了RuO2／γ-A12O3和RuO2／CeO2／γ-A12O3催化剂湿式氧化降解苯酚的活性，并深入探讨了Ce对RuO2／γ-A12O3催化剂的助催化作用。结果表明：Ce掺杂改性后，使催化剂表面Ru的化学态降低、表面氧空位增加，并且活性组分Ru的分散性增加，从而使RuO2／CeO2／γ-A12O3催化剂的活性提高，因此Ce起到了显著的助催化作用。     

焙烧温度对Ce0.65Zr0.35O2储氧材料性能的影响

用共沉淀法制备了Ce0.65Zr0.35O2氧化物,对不同温度处理后的样品进行了XRD、Raman、BET和储氧量(OSC)的表征.并考察了不同温度焙烧后的氧化物对单钯催化剂三效性能的影响.结果表明,焙烧温度的不同,样品具有不同的织构性能,但该样品的晶相结构稳定,老化前后均为立方相的铈锆固溶体,经1000℃焙烧后未出现相分离,说明该氧化物具有良好的热稳定性能;活性测试结果表明,不同焙烧温度的载体对催化活性影响较大,并以700℃焙烧后的氧化物为载体的催化剂具有最好的三效性能.     

Zr掺杂CeO_2电子结构的密度泛函计算

根据密度泛函理论,采用"总体能量平面波"超软赝势方法,对不同的Zr掺杂浓度的CeO2晶体几何结构进行了优化,从理论上给出了Zr掺杂CeO2晶体结构参数及性质;计算了Zr掺杂情况下CeO2晶体的总体能量、能带结构、总波态密度和分波态密度。研究表明,Zr3+取代Ce4+及Ce3+后晶体的稳定性增强,同时掺杂Zr使得晶格中自由载流子电子和O2p的波态密度的增加,使得晶格中Ce3+和Ce4+之间的变价可能性增大。     

Study on the Properties of Nanometer CeO2 Doped with Zr4+, La3+, Pr3+

Different nanometer CeO_2-ZrO_2 mixed oxides doped with lanthanum or praseodymium were prepared by coprecipi-tation. The characteristics of all mixed oxides were tested by XRD, SEM, TEM, and XPS. XRD results showed thatall oxides were formed solid solution with CaF_2 structure at low temperature and had good thermal stability. MoreCe~(4+) ions were rich on the surface by XPS, which were beneficial to oxygen storage. The particle mediun sizes (d_(50))of all oxides powders were approximately 10～20 nm by small angle scattering goniometer. When doped Zr~(4+) inCeO_2, the specific surface areas were improved at low or high temperature. The area of Ce_(0.6)Zr_(0.3)La_(0.04)Pr_(0.06)O_2powder had excess 110 m~2/g after calcining at 923 K for 4 h, even calcined at 1273 K for 4 h, the area was up to65 m~2/g.     

Effect of metal doping into Ce0.5Zr0.5O2 on photocatalytic activity of TiO2/Ce0.45Zr0.45M0.1OX (M=Y, La, Mn)

The paper demonstrates that the photocatalytic activity of TiO2 towards the decomposition of gaseous benzene in a batch reactor can be greatly improved by loading TiO2 on the surface of CeO(2)-ZrO(2). The research investigates the effects of three metals doping into Ce(0.5)Zr(0.5)O(2) on photocatalytic activity of TiO2/Ce(0.45)Zr(0.45)M(0.1)O(X) (M=Y, La, Mn). The prepared photocatalysts were characterized by BET, XRD, UV-vis diffuse reflectance and XPS analyses. BET surface area of TiO2/Ce(0.45)Zr(0.45)M(0.1)O(X) (M=Y, La, Mn) is smaller than that of Ce(0.5)Zr(0.5)O(2). XRD results reveal that the deposited titania is highly dispersed as in the CeO(2)-ZrO(2) matrix, doping M in the CeO(2)-ZrO(2) lattice causes the changing of lattice space and the diffraction peaks shift to higher 2theta position. Among these four catalysts, the band gap value of TiO(2)/Ce(0.45)Zr(0.45)La(0.1)O(X) is the lowest. The binding energy value of Ti 2p(3/2) of four catalysts transfers to a lower value. The order of photocatalytic activity is TiO2/Ce(0.45)Zr(0.45)La(0.1)O(X)>TiO2/Ce(0.45)Zr(0.45)Y(0.1)O(X)>TiO2/Ce(0.45)Zr(0.45)Mn(0.1)O(X)>TiO2/Ce(0.5)Zr(0.5)O(2)>TiO2. The proposed mechanism is of electron transfer and the stronger absorption in the region 210-400 nm.     

Transmitted-light microscopy - a new method for surface structure analysis of cleanable non-woven dust filter media

A series of CeO(2)-ZrO(2) mixed oxides were prepared using coprecipitation method and characterized by BET, oxygen storage capacity (OSC), X-ray diffraction (XRD) and H(2)-temperature-programmed reduction (H(2)-TPR). The catalytic activities toward toluene combustion were investigated in a micro-reactor. The results demonstrate that the catalytic activity of Pt/gamma-Al(2)O(3)/Ce(0.50)Zr(0.50)O(2) monolithic catalyst can be greatly improved by doping metal into Ce(0.50)Zr(0.50)O(2). When doping Y and Mn into Ce(0.50)Zr(0.50)O(2) simultaneously, the catalyst Pt/gamma-Al(2)O(3)/Ce(0.40)Zr(0.40)Y(0.10)Mn(0.10)O(X) shows the highest activity. The T(10) (the temperature of 10% toluene conversion) and the complete conversion temperature (the temperature of 90% toluene conversion) of toluene are 443 and 489K, respectively. Gas hourly space velocity (GHSV) results show that the prepared catalyst can be applied in a wide range of GHSV (from 12,000 to 20,000h(-1)). The catalyst prepared shows great potential for practical application.     

纳米Ce0.8Zr0.2O2固溶体的溶剂热制备与催化性能研究

以硝酸铈和硝酸锆为原料用溶剂热的方法在甲酸中120℃加热24h制得了纳米Ce0.8Zr0.2O2固溶体材料,利用X射线衍射（XRD）、Raman光谱、扫描电镜（SEM）和投射电镜（TEM）对其进行了表征。在乙酸和正丁醇制备乙酸丁酯的反应中考察了其催化活性。XRD和Raman光谱显示出所制备的样品形成了具有氧化铈立方结构的均一固溶体。TEM结果表明所合成的Ce0.8Zr0.2O2的粒径〈100nm。在酯化反应中,Ce0.8Zr0.2O2固溶体具有较高的催化活性,且容易和反应液分离。反复实用10次后,其催化活性基本上保持不变。     

Removal of oxygenated volatile organic compounds by catalytic oxidation over Zr-Ce-Mn catalysts

The composition-activity relationship of Zr-Ce-Mn-O materials was investigated for the catalytic removal of Oxygenated Volatile Organic Compounds (OVOC) emitted by stationary sources. Using a sol-gel method, very high surface specific areas, small crystallite sizes and high redox properties were obtained for Zr(0.4)Ce(0.6-x)Mn(x)O(2) catalytic systems after calcination at 500°C. The textural and redox properties were improved when Mn content increased in the material, especially for x=0.36. As a result the most active and selective catalyst in the butanol (model of OVOC) oxidation was obtained for the nominal composition Zr(0.4)Ce(0.24)Mn(0.36)O(2) due to a high oxygen mobility and surface Mn(4+) concentration.     

接枝聚合聚苯胺/CeO2-COOH复合材料的性能及聚合机制

对二氧化铈(CeO2)进行羧基化改性得到羧基化二氧化铈(CeO2-COOH),并与苯胺(An)接枝聚合得到核壳结构聚苯胺/二氧化铈复合材料(PANI/CeO2-COOH)。采用红外光谱、X射线光电子能谱、X射线衍射、热重分析、扫描电子显微镜及旋转圆盘电化学测试技术分析材料的结构及性能。结果表明,CeO2-COOH的CeIII/CeIV的比值接近1,具有较高的表面氧空位;PANI/CeO2-COOH中PANI接枝效果较好,而且与纯PANI结构相同;CeO2-COOH与PANI之间通过价键接枝形成的PANI/CeO2-COOH复合材料起始分解温度在228℃左右,且在200~600℃内的分解速率较慢,表现出较好的热稳定性;在1mol/LH2SO4中对电极进行循环伏安和恒电流充放电测试,PANI/CeO2-COOH复合材料电极不仅具有良好的峰对称性和最高阳极峰电流,而且还具有较好的电容性能,当电流密度为0.5A/g时,比电容达到149.5F/g。     

微波均相合成Ce_(0.75)Zr_(0.25)O_2粉体及其烧结性

以Ce(NO3)3.6H2O和ZrOCl2.8H2O为原料,以尿素为沉淀剂,利用微波均相法制备Ce0.75Zr0.25O2粉体,采用热分析仪、X射线衍射仪、扫描电子显微镜表征制备的粉体,对制备的粉体压制成型并烧结,用扫描电子显微镜观察烧结体的微观结构。结果表明,合成Ce0.75Zr0.25O2前驱体时加入2倍于Ce3+物质的量的H2O2可以减小固溶体颗粒粒度,降低固溶温度30℃;所制备的固溶体粉体具有良好的烧结性,在1 550℃得到烧结体的相对密度达99.57%。     

Thermally stable Ir/Ce<Subscript>0.9</Subscript>La<Subscript>0.1</Subscript>O<Subscript>2</Subscript> catalyst for high temperature methane dry reforming reaction

In this study,the use of a thermally stable Ir/Ce0.gLa0.1O2 catalyst was investigated for the dry reforming of methane.The doping of La2O3 into the CeO2 lattice enhanced the chemical and physical properties of the Ir/Ce0.9La0.1O2 catalyst,such as redox properties,Ir dispersion,oxygen storage capacity,and thermal stability,with respect to the Ir/CeO2 catalyst.Hence,the Ir/Ce0.gLa0.1O2 catalyst exhibits higher activity and stabler performance for the dry reforming of methane than the Ir/CeO2 catalyst.This observation can be mainly attributed to the stronger interaction between the metal and support in the Ir/Ce0.gLa0.1O2 catalyst stabilizing the catalyst structure and improving the oxygen storage capacity,leading to negligible aggregation of Ir nanoparticles and the Ce0.gLa0.1O2 support at high temperatures,as well as the rapid removal of carbon deposits at the boundaries between the Ir metal and the Ce0.gLa0.1O2 support.     

Study of Thermodynamic Properties of Nonstoichiometric Phase with Compound Energy Model

Using compound energy model (CEM), the thermodynamic properties of and were evaluated. The evaluation was based on the optimization of ZrO2-CeO2 and ZrO2-CeO1.5 systems, as well as the miscibility gap in CeO1.5-CeO2 system. Except the cubic fluorite structure phase assessed with compound energy model, all the other solution phases were assessed with subsitutional solution model. The model parameters were evaluated through fitting the selected experimental data by means of thermodynamic optimization. A set of parameters with thermodynamics self-consistency was obtained and satisfactorily described the complex relation between y in and the partial pressure of oxygen at different temperatures, also the interdependence among miscellaneous factors such as temperature, oxygen partial pressure, the reduction amount of CeO2 as well as the nonstoichiometry in cubic phase . The calculated results seem to be reasonable when put into the explanation of pressureless sint