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 LaMexAl12-xO19-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.