共沉淀-超临界干燥法制备La2CoxSn2-xO7烧绿石及其甲烷燃烧性能  

Methane Catalytic Combustion Over La_2Sn_(2-x)Co_xO_7 Pyrochlores Prepared by Coprecipitation and Supercritical Drying

作　　者：孙德印[1,2] 杨帆[1,2] 蒋政[2] 张涯远[2] 谢华[1] 王辉[3] 李福俊[1] 

机构地区：[1]中国矿业大学北京化学与环境工程学院,北京100083 [2]中国科学院过程工程研究所多相复杂系统国家重点实验室,北京100080 [3]华北电力大学能源与动力工程学院,北京102206

出　　处：《中国稀土学报》2009年第3期313-318,共6页Journal of the Chinese Society of Rare Earths

基　　金：国家863高技术研究计划(2007AA03Z439);中国科学院优秀青年创新人才项目;中国科学院院长启动基金

摘　　要：采用共沉淀-超临界干燥法制备了Co取代型La2CoxSn2-xO7(x=0,0.1,0.2,0.3,0.4,0.5)烧绿石甲烷催化燃烧催化剂,并采用XRD,SEM,BET,TPR等技术对催化剂进行表征。结果表明,当x≤0.4时,Co部分取代Sn进入烧绿石晶格,生成单相烧绿石,更高的取代量导致Co3O4相析出。La2CoxSn2-xO7催化剂颗粒聚集体尺寸在60～100nm之间,其形貌受钴含量影响。虽然Co取代降低了催化剂的比表面积,但大幅提高了甲烷催化活性,其中,La2Co0.3Sn1.7O7的催化燃烧活性最高。催化剂结构中Co-Sn之间存在的强相互作用决定了材料的催化活性。Cobalt-substituted lanthanum stannate （LaECoxSn2-xO7, x=0, 0.1, 0.2, 0.3, 0.4, 0.5） catalysts were prepared by calcinations of aerosol precursors synthesized via coprecipitation and supereritical drying. As x ≤0.4, the cobalt could well incorporate into La2CoxSn2-xO7 matrixes to form single phase pyroehlore crystals, and the higher cobalt loading led to present Co3O4 phase. The sizes of loosely aggregated catalyst particles were within 60- 100 nm range.The presences of cobalt in pyrochlore matrices significantly decreased their specific surface areas, but remarkably improve the methane catalytic combustion activities. The best methane ignition activity could be observed on La2Co0.3 Sn1.7 O7. The catalytic combus- tion performance of the catalysts was tentatively attributed to the strong interaction between Co and Sn in the La2 CoxSn2-xO7 structures.

关 键 词：超临界干燥 烧绿石 甲烷催化燃烧 稀土 

分 类 号：O643[理学—物理化学]