镧系六铝酸盐催化剂制备及甲烷燃烧催化性能表征  

La-Hexaaluminate Catalyst Preparation and Its Methane Catalytic Combustion

作　　者：崔梅生[1] 王良士[2] 侯永可[1] 刘营[1] 李殿卿[2] 陈霭璠[2] 

机构地区：[1]北京有色金属研究总院有研稀土新材料股份有限公司,北京100088 [2]北京化工大学理学院,北京100029

出　　处：《中国稀土学报》2007年第2期178-182,共5页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金(20476012);北京市自然科学基金(2062017)资助项目

摘　　要：采用可控共沉淀法以NH4HCO3和NH4OH组成的缓冲溶液作为沉淀剂制备六铝酸盐,采用BET,XRD,TPR等技术考察了催化剂的物化性能。以甲烷催化燃烧为探针反应,对催化剂进行了催化性能表征,并研究了铈取代对催化性能的影响。结果表明:采用NH4HCO3和NH4OH缓冲溶液作为沉淀剂使沉淀更均匀,可合成化学均一的六铝酸盐。La系六铝酸盐可在较低焙烧温度1050℃形成,稀土离子Ce主要是以高储放氧能力的CeO2相存在,与Mn之间存在协同作用提高了催化活性。当Mn取代度为2时,LaMnxAl12-xO19催化性能最佳,此时具有较高的氧化还原性能。Mn容易进入六铝酸盐晶格,Mn取代的La系六铝酸盐催化剂是很有前途的高温甲烷燃烧催化材料。The La-hexaaluminate catalysts with high performance were synthesized by the controllable coprecipitation method with NH4HCO3 and NH4OH buffer solution as a precipitation agent. The physicochemical properties were characterized by means of BET, XRD and TPR techniques. With methane catalytic combustion as the probe reaction, the catalytic property was also tested on a fixed bed, continual flow system. The cerium substitution and its effects on the structure and catalytic activity were also studied. The results showed that it was a good method to obtain chemical homogeneous hexaaluminate materials using the buffer solution of NH4HCO3 and NH4OH mixture as precipitation agent. The Laexaaluminate can be formed at a more low temperature of 1050 ℃, and the cerium substitution plays a great role to the methane catalytic combustion on La-Mn hexaaluminate because of its high oxygen storage capacity and the well synergic effect between Ce and Mn. When Mn substitution was 2, the La-hexaaluminate showed the highest activity, and the catalyst possessed good H2 consumption and redox performance from the TPR pattern. The XRD showed that Mn could easily enter the hexaaluminate crystal lattice, which revealed that the Mn substituted La-hexaaluminate was a promising high temperature methane combustion catalyst with high activity and good stability.

关 键 词：甲烷 催化燃烧 六铝酸盐 稀土 

分 类 号：O643.3[理学—物理化学] O614.3[理学—化学]