摘要
在反相微乳液中以碳酸铵共沉淀法制备了LaMnAl11O19α甲烷燃烧催化剂,比较了反相微乳液法与普通碳酸铵共沉淀法对催化剂相结构、比表面积、孔结构及其催化甲烷燃烧性能的影响.结果表明,反相微乳液法制备的催化剂前驱体平均粒径为2.3nm,而普通碳酸铵共沉淀法得到的催化剂前驱体平均粒径为30.1nm.在乙醇超临界干燥阶段,反相微乳液法制备的催化剂前驱体较容易发生铝羟基分子间脱水,形成较为丰富的孔,保持了各组分分布的均匀性,从而促进了六铝酸盐的形成,所得样品具有较大的比表面积和较高的催化甲烷燃烧的活性.
La and Mn substituted hexaaluminate catalyst LaMnAl11O19-α was synthesized by reverse microemulsion-mediated （ NH4 ）2CO3 coprecipitation and conventional （ NH4 ）2CO3 coprecipitation methods. Effects of preparation methods on the phase composition, BET surface area, pore construction and methane combustion activity of the catalyst were investigated. The results show that the average diameter of the precursor particles formed in the reverse microemulsion is 2.3 nm, which is much smaller than that （30.1 nm ） prepared by conventional （NH4）2CO3 coprecipitation. DTA results indicate that the smaller precursor particles aggregate easily in the supercritical drying process due to the dehydration among Al（OH）3 molecules, and abundant pores form. XRD spectra show that the precursor formed in the reverse microemulsion can be converted to hexaaluminates more easily after calcination at 1 200 ℃ . The BET surface area of LaMnAl11O19-α prepared in reverse microemulsion is 34.01 m^2/g, while that prepared by conventional （NH4）2CO3 coprecipitation is 26.92 m^2/g. The temperatures （T10） at which 10% methane is converted over the two samples are 455 and 505 ℃ , respectively.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2005年第8期665-668,共4页
基金
国家重点基础研究发展规划项目(973计划)资助项目(G1999022401).
关键词
甲烷
催化燃烧
六铝酸盐
反相微乳液
镧
锰
碳酸铵
共沉淀
methane, catalytic combustion, hexaaluminate, reverse microemulsion, lanthanum, manganese,ammonium carbonate, coprecipitation
