堇青石负载La-Mn-O复合氧化物催化剂的甲苯催化燃烧性能

以堇青石蜂窝陶瓷为载体,以La2O3,Mn(NO3)2为基本原料,掺杂一些稀土等非贵重金属元素,采用浸渍法制备了系列负载La-Mn-O复合氧化物催化剂.考察了焙烧温度等对甲苯催化燃烧性能的影响,并对催化剂进行了XRD,TPR表征.结果表明,800 ℃焙烧的LaMn/Cord催化剂具有较高的甲苯催化燃烧性能;Ce取代催化剂中部分La后能改善催化剂的氧化活性,当Ce∶La=1∶1(摩尔比)时催化性能最佳,在260 ℃的反应温度下甲苯转化率达到90%以上.     

纳米涂层对钙钛矿基整体式催化剂催化燃烧VOCs性能的影响

以堇青石蜂窝陶瓷为基体,纳米氧化物(CeO2、γ-Al2O3、SiO2)为涂层载体,通过悬浮涂渍法和溶胶-凝胶法两步制得LaCoO3/CeO2/堇青石、LaCoO3/γ-Al2O3/堇青石、LaCoO3/SiO2/堇青石三种整体式催化剂.通过XRD、SEM、XPS、H2TPR、UT和N2吸附-脱附等技术,对样品的物相、...     

稀土钙钛矿型氧化物催化剂的研究进展

综述了近年来国内外稀土钙钛矿型氧化物催化剂在一氧化碳氧化、甲烷氧化、乙烷氧化、氮氧化物消除和汽车尾气净化等方面的研究进展, 讨论了该类催化材料的结构缺陷与性能之间的构效关系, 简要地分析了今后我国开展稀土钙钛矿型氧化物催化剂研究的重要性及其应用前景.     

柠檬酸浓度对钙钛矿型催化剂结构及其催化性能的影响研究

以催化甲烷燃烧为目标反应,采用溶胶凝胶法制备钙钛矿型氧化物LaFe_0.6Ni_0.4O₃,其结构经XRD、 SEM、BET、 H₂-TPR和TG-DSC表征。研究了不同倍数柠檬酸（R=1.5、 1.75、 2、 2.25、 2.5）对钙钛矿晶体结构和催化活性的影响。结果表明：柠檬酸浓度对催化剂的结构及催化活性均有一定程度影响。当柠檬酸浓度加入倍数R为1.5时,金属与氧之间的化学键更易断裂,可使更多的活性氧参与反应。R=1.5对应的催化剂催化活性最好,起燃温度为378 ℃、最终反应温度为547 ℃时。      

负载型镧锰钙钛矿催化剂上甲烷催化燃烧的研究

研究了甲烷在负载型镧锰钙钛矿催化剂(LCFM／α-Al2O3)上的低温催化燃烧反应．考察了制备方法、焙烧温度列催化剂结构和活性的影响．并进行了100h稳定性实验．实验结果表明用浸渍法、焙烧温度高于800℃就能在载体上生成良好的钙钛矿结构，催化剂具有较低的起燃温度并且在高温条件下具有与非负载型镧锰钙钛矿催化剂相当的活性；100h稳定性实验表明LCFM／a-Al2O3催化剂经历了100h．800℃的连续高温燃烧反应，催化剂仍保持了原有结构和催化活性．并且没有明显积碳．     

钙钛矿型催化剂对VOCs催化燃烧的抗毒性和稳定性研究

采用共沉淀法制备了钙钛矿型La0.8Cu0.2MnO3和La0.8Sr0.2MnO3催化剂,考察了两种催化剂对含硫、含氯VOCs气体催化燃烧的抗毒性和稳定性.结果发现,两种催化剂具有良好的抗氯性,但在SO2存在下会出现中毒失活现象,相比较而言,La0.8Sr0.2MnO3比La0.8Cu0.2MnO3具有更好的抗硫性和结构稳定性;采用XRD和XPS分析方法研究催化剂硫中毒机理,发现其失活原因在于催化剂表面生成CuSO4和SrSO4,形成屏蔽效应导致催化剂失活.     

镧钴镍复合氧化物催化剂的制备及催化甲烷燃烧活性研究

采用共沉淀法制备LaNi_1-xCo_xO₃系列催化剂(x=0,0.2,0.4,0.6,0.8,1.0),研究B位离子Co的掺杂对单钙钛矿LaNiO₃催化甲烷燃烧性能的影响。通过X射线衍射(XRD)、比表面积测定(BET)、程序升温还原(H₂-TPR)、扫描电镜(SEM)、热重分析(TG-DSC)等实验技术对催化剂的结构和性能进行考察,以催化甲烷燃烧为目标,考察其对催化剂性能的影响。研究结果表明：Co离子的掺杂会改变单钙钛矿的晶型结构,改善催化活性,当x=0.8时,LaNi_0.2Co_0.8O₃的催化甲烷燃烧活性最好,其比表面积为22.4 m^₂.g^_-1,T_10%(起燃温度)为475℃,T_90%(完全转化温度)为610℃,反应活化能最小,为91.4KJ/mol。     

Y2O3涂层负载Pd整体式催化剂的制备和催化性能

以Y(NO3)3为前驱体制备了Y2O3涂层的堇青石蜂窝陶瓷载体.扫描电子显微镜、X射线能谱和超声波振荡等表征结果表明,Y2O3涂层不但具有良好的抗振荡性和粘结强度,而且具有很强的吸附催化剂活性组分(H2PdCl4)的能力,适合制备负载型Pd催化剂.以甲苯和乙酸乙酯完全燃烧为模型反应考察了催化剂的活性,发现以Y2O3涂层堇青石蜂窝陶瓷为载体的整体式Pd/Y2O3催化剂具有良好的催化活性和热稳定性,甲苯和乙酸乙酯催化燃烧的T99分别为210和300℃;催化剂经900℃焙烧4 h后,T99仅提高20℃,表明催化剂具有很高的热稳定性.催化剂的X射线衍射、拉曼光谱和程序升温还原结果表明,Pd/Y2O3催化剂经低温焙烧时,Y2O3和PdO均高度分散在堇青石蜂窝陶瓷的表面,而高温焙烧使催化剂活性组分PdO晶粒增大,从而导致催化剂活性下降.     

CeO2-Y2O3涂层和负载型Pd催化剂催化燃烧VOCs

制备了一种粘附在堇青石蜂窝陶瓷载体上的CeO_2-Y_2O_3(CeY)复合氧化物新涂层.以二氧化铈和柠檬酸钇为前驱体,制备过程中无有害物质产生,对环境友好.CeY涂层和Pd/CeY催化剂通过SEM、EDX、XRF和Raman光谱等表征.结果表明,此涂层的粘结强度高,对活性组分的吸附性能好,适合用来负载钯催化剂.Y_2O_3大部分进入了峰窝陶瓷的孔道内,CeO_2和Pd物种则富集在载体的表面.以CO、甲苯和乙酸乙酯的催化燃烧来评价Pd/CeY催化剂的性能,此催化剂具有较好的催化活性和热稳定性.500℃焙烧的催化剂,CO、甲苯和乙酸乙酯的T_(99)(转化率99%以上所需的最低反应温度)分别为150、220和310℃;1050℃焙烧的催化剂,它们的T_(99)分别为180、250和330℃.高温焙烧的催化剂,活性物种PdO的晶粒增大,这可能导致催化剂的活性下降.     

La-Ni-Al钙钛矿氧化物中Sr和Ca取代La对甲醇重整的影响

Mixed perovskite oxides with CaxLa1-xNi0.3Al0.7O3-d and SrxLa1-xNi0.3Al0.7O3-d(x=0,0.2,0.5,0.8,and 1.0;d=0.5x)components have been prepared by a sol-gel method.The effects of the partial substitution of La by Ca and Sr in dry CH4 reforming were investigated at 500-800 ℃ and 101 kPa.The resulting oxides were examined by Fourier-transform infrared spectroscopy,X-ray diffraction,temperature-programmed reduction,scanning electron microscopy,energy dispersive X-ray spectrometry,and BET surface area analysis.Studies following the catalytic tests by carbon analysis show some carbon deposition on this catalytic system.The results indicate that all initial salt entered into a propionate structure,and that most of the solid solution has well defined perovskite structure with surface areas between 3.5 and 9.5 m2/g.Most of the catalysts performed well in the dry reforming,with CH4 conversions up to 90%,H2 yields up to 80%,and H2 selectivity up to 90%.Among the samples,Sr0.2La0.8Ni0.3Al0.7O2.9 showed an excellent catalytic performance in CH4 dry reforming,with a H2/CO ratio of 1,whereas Ca0.8La0.2Ni0.3Al0.7O2.6 showed the lowest coke formation(approximately 0.71%).     

NO对LaMnO3与La0.8K0.2MnO3催化氧化碳烟活性影响

采用柠檬酸络合法制备LaMnO3和La0.8K0.2MnO3钙钛矿催化剂,运用程序升温氧化(TPO)考察在不同反应气氛下催化燃烧碳烟的活性,并通过XRD,O2-TPD,NO-TPD,XPS以及NO预处理后O2-TPD等技术对催化剂进行表征和分析。结果表明,NO的存在促进了碳烟的催化氧化,但是对LaMnO3和La0.8K0.2MnO3氧化碳烟的促进效果不同。这与催化剂表面氧空位和活性氧物种有密切联系。     

La0.8Sr0.2MnO3水基料浆稳定性的研究

通过调节pH值和添加分散剂的量来研究La0.8Sr0.2MnO3水基料浆的悬浮性和稳定性.结果表明, pH在碱性条件下(pH>8),分散剂添加量为0.2% 时,锰酸镧水基料浆具有良好的稳定性.     

Chemical and physical properties of complex perovskites in the La0.8Sr0.2MnO3−δ–La0.8Sr0.2CuO2.4+δ–La0.8Sr0.2FeO3−δ system

Perovskites resulting from discrete changes in composition within the quasi-ternary system La_0.8Sr_0.2MnO_3−δ–La_0.8Sr_0.2CuO_2.4+δ–La_0.8Sr_0.2FeO_3−δ were investigated under constant experimental conditions with the objective of obtaining an overview of the variation of the properties relevant for possible future applications. Nineteen nominal perovskite compositions within this system were systematically selected and synthesized under identical conditions by the Pechini method. The experimental data obtained on quantitative chemical analysis, powder X-ray diffraction, electrical conductivity and thermal expansion are presented collectively for the first time to facilitate comparisons. The formation and distribution of the different crystallographic phases at 950 °C within this quasi-ternary system are shown. The DC electrical conductivity is strongly influenced by the Cu content and increases up to 276 S cm⁻¹ for La_0.8Sr_0.2CuO_2.4+δ. The thermal expansion is dominated by the Cu/Mn ratio and is almost independent of the Fe content.     

Characterization of La0.8Sr0.2MnO3 Produced by a Reactive DC Thermal Plasma Spray System

An atmospheric pressure, reactive DC plasma spray system was used to evaluate a process for depositing porous, complex oxide thin films. A mixture of La₃O₃, SrCO₃, and MnCo₃ was used to produce a porous cathode layer for potential application in planar solid oxide fuel cells. The coated lanthanum strontium manganite (LSMO) layer made from the mixture was compared to ones generated using a pre-reacted LMSO powder made by solid-state reaction. The results showed that the crystallization of the reactive-spray formed coating layer on the zirconia substrate was higher than that of the coating layer on the mild steel from the pre-reacted LMSO powder. It is both a simpler process and gave better crystallization. The controlled porous coating layers with open pore size of less than 1 m were successfully produced in a reactive DC plasma spray system from the mixture of raw materials.     

钙钛矿型La0.8Sr0.2FeO3中的晶格氧用于甲烷选择氧化制取合成气

 用自燃烧法制备了钙钛矿型La0．8Sr0．2FeO3催化剂．用H2－TPR考察了催化剂表面的氧消耗过程，用程序升温表面反应（TPSR）研究了甲烷与催化剂表面氧物种的反应，用在线质谱脉冲反应和甲烷／氧切换反应研究了催化剂的晶格氧选择氧化甲烷制合成气．结果表明，催化剂上存在两种氧物种，无气相氧存在时，强氧化性氧物种首先将甲烷氧化为CO2和H2O；而后提供的氧化性较弱的晶格氧具有良好的甲烷部分氧化选择性，可将甲烷氧化为合成气CO和H2（选择性可达95％以上）．在900℃下的CH4／O2切换反应结果表明，甲烷能与La0．8Sr0．2FeO3中的晶格氧反应选择性地生成CO和H2，失去晶格氧的La0．8－Sr0．2FeO3能与气相氧反应恢复其晶格氧．在合适的反应条件下，用La0．8Sr0．2FeO3催化剂的晶格氧代替分子氧按Redox模式实现甲烷选择氧化制合成气是可能的．     

有机燃料对合成大比表面积La0．8Sr0．2CoO3性能的影响

采用溶液燃烧合成法(solution com bustion synthesis,简称SCS)制备了La0.8Sr0.2CoO3钙钛矿复合氧化物,考察了丙氨酸、氨基乙酸和丙三醇等有机燃料对催化剂结构和CH4催化燃烧活性的影响,并运用XRD、FI-TR、BET、TPR等技术进行了表征。结果表明,不同有机燃料所制La0.8Sr0.2CoO3复合氧化物均具有较大比表面积,有机燃料对催化剂的结构和性能有较大的影响,其中以丙氨酸有机燃料制备的复合氧化物活性最好,其T50和T100分别为470℃和550℃。该法所制La0.8Sr0.2CoO3复合氧化物的平均晶粒度较小,比表面积和晶格畸变率较大,表面和氧空穴处的化学吸附氧较易移动,表观活化能较低。     

La0.8Sr0.2MnO3／YSZ高温电极交流阻抗研究

用交流阻抗方法研究了Ｌａ０．８Ｓｒ０．２ＭｎＯ３电极上进行的氧化电化学还原反应。实验表明反应速度控制步骤随反应温度，氧分压及过电位发生显著变化，近平衡下反应的ｒｄｓ为氧的解离吸附过程。强阳极极化下，电解质表面产生大量电子空穴；强阴极极化下，ＬＳＭ电极表面形成大量氧空位，二者的结果均使界面电导增加，电化学反应区扩展。     

Efficiency of 3D-Ordered Macroporous La0.6Sr0.4Co0.2Fe0.8O3 as an Electrocatalyst for Aprotic Li-O2 Batteries

Li-O₂ batteries (LOBs) with an extremely high theoretical energy density have been reported to be the most promising candidates for future electric storage systems. Porous catalysts can be beneficial for LOBs. Herein, 3D-ordered macroporous La_0.6Sr_0.4Co_0.2Fe_0.8O₃ perovskite oxides (3D-LSCF) are applied as cathode catalysts in LOBs. With a high Brunauer-Emmett-Teller surface area (21.8 m² g⁻¹) and unique honeycomb-like macroporous structure, the 3D-LSCF catalysts possess a much higher efficiency than La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF) nanoparticles. The unique 3D-ordered macropores play a significant role in the product deposition as well as oxygen and electrolyte transmission, which are crucial for the discharge-charge processes of LOBs.     

Comparison of LaFeO3, La0.8Sr0.2FeO3, and La0.8Sr0.2Fe0.9Co0.1O3 perovskite oxides as oxygen carrier for partial oxidation of methane

Comparison of LaFeO3, La0.8Sr0.2FeO3, and La0.8Sr0.2Fe0.9Co0.1O3 perovskite oxides as oxygen cartier for partial oxidation of methane in the absence of gaseous oxygen was investigated by continuous flow reaction and sequential redox reaction. Methane was oxidized to syngas with high selectivity by oxygen species of perovskite oxides in the absence of gaseous oxygen. The sequential redox reaction revealed that the structural stability and continuous oxygen supply in redox re-action decreased over La0.8Sr0.2Fe0.9Co0.1O3 oxide, while LaFeO3 and Lao.sSro.2FeO3 exhibited excellent structural stability and continuous oxygen supply.     

Comparison of LaFeO3, La0.8Sr0.2FeO3, and La0.8Sr0.2Fe0.9Co0.1O3 perovskite oxides as oxygen carrier for partial oxidation of methane

Comparison of LaFeO3, La0.8Sr0.2FeO3, and La0.8Sr0.2Fe0.9CO0.1O3 perovskite oxides as oxygen carrier for partial oxidation of methane in the absence of gaseous oxygen was investigated by continuous flow reaction and sequential redox reaction, Methane was oxidized to syngas with high selectivity by oxygen species of perovskite oxides in the absence of gaseous oxygen. The sequential redox reaction revealed that the structural stability and continuous oxygen supply in redox reaction decreased over La0.8Sr0.2Fe0.9Co0. 1O3 oxide, while LaFeO3 and La0.8Sr0.2FeO3 exhibited excellent structural stability and continuous oxygen supply.