逆微乳液体系研制镧系六铝酸盐甲烷燃烧催化剂

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

采用逆微乳液为媒介合成对甲烷燃烧有高温热稳定性又有催化活性的六铝酸镧催化剂的前躯体。分别用十二烷基磺酸钠(SDS)和十六烷基三甲基溴化铵(CTAB)作为表面活性剂,脂肪醇作助表面活性剂,分别用水和正辛烷作分散相和连续相,绘制四组分拟三元体系相图,考察影响微乳液形成和稳定的因素,选取形成微乳液的最佳条件和合适配比进行反应,在较低温度(1050℃)下焙烧转化成六铝酸盐催化剂,并考察和讨论了Fe,Mn金属离子取代的镧系同晶催化剂对甲烷燃烧催化活性的影响。

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.