Abstract: The Mn and Fe substituted hexaaluminate catalysts for high temperature combustion of methane were prepared by the chemically controlled co-precipitation method.Structural evolution during heat treatment provided useful information on the microstructural stability and amount of hexaaluminates.The effect of calcination temperature and substitution degree of Mn and Fe on specific surface, structure and catalytic activity for methane combustion was investigated over LaMexAl_12-xO_19-δ(Me＝Fe，Mn) catalysts.The experimental results showed that the crystalline phase of hexaaluminate was observed in the XRD patterns when the catalyst precursor was calcined at 1000℃ and the amount of hexaaluminate phase was increased at 1200℃.The research results also indicated that the enhancement in crystallinity of hexaaluminate was caused by substitution of Mn and Fe ions in the structure .It was accompanied by an increase in crystal size and a decrease in specific surface area.XPS and TPR analysis showed that the valence states of substituted manganese ions were divalent and trivalent, and substituted iron ions were trivalent.The combustion of methane was tested over the different catalysts in order to compare their activity.The catalytic activity was greatly enhanced with the substitution of Mn and Fe ions for Al ions of hexaaluminates.Among these catalysts LaMnAl₁₁O₁₉ and LaFe₂Al₁₀O₁₉ exhibited the highest activity in the combustion of methane.

摘要： 采用化学可控共沉淀法制备了系列取代六铝酸盐LaMe_xAl_12-xO_19-δ（Me＝Fe、Mn）催化剂，研究了焙烧温度和Fe、Mn的离子取代量对催化剂比表面、结构及甲烷催化燃烧活性的影响.结果表明，催化剂前驱物经1000℃焙烧，催化剂中开始有六铝酸盐晶相生成; 当焙烧温度提高到1200℃时，样品主要以六铝酸盐晶相存在.增加Fe、Mn离子取代量可以提高六铝酸盐晶相的结晶度，但同时导致晶粒增大，引起比表面下降.由XPS和TPR分析表明，Mn在六铝酸盐结构中以+2价和+3价混合价态存在，而Fe以+3价形式存在.用Fe和Mn离子取代晶格中的Al³⁺大大提高了六铝酸盐对甲烷催化燃烧活性，当Mn离子的取代数为1，Fe离子的取代数为2时催化剂的活性最高.