La-hexaaluminate Catalyst Preparation in Microemulsion and Its Catalytic Activity for Methane Combustion

The La-hexaaluminate catalyst with high temperature stability and catalytic activity was successfully synthesized by the reverse microemulsion method using the buffer solution of NH4HCO3 and NH4OH as a precipitation agent.With methane catalytic combustion as a probe reaction,the catalytic activity was examined on a fixed bed flow reaction system in order to compare their catalytic activity.The tested results showed that the hexaaluminate precursor formed in reverse microemulsion with chemical homogeneouness,and the La-hexaaluminate catalytic crystalline formed at a lower temperature of 1050 ℃.The catalytic activity was greatly enhanced with the substitution of Fe or Mn ions for Al ions in hexaaluminates,and the Fe-substituted La-hexaaluminate catalysts exhibited the high temperature activity and stability.The Mn-substituted La-hexaaluminate catalysts exhibited low temperature catalytic activity.The research results also indicated that the Fe-and Mn-substituted La-hexaaluminate catalysts exhibited the highest catalytic activity on the catalytic combustion of methane,and their effects on the structure and catalytic activity were also studied,due to the well synergic effect between Fe,Mn and La ions of La-hexaaluminates.