制备方法对BaAl_(12)O_(19-α)催化剂结构和甲烷催化燃烧活性的影响

采用反相微乳液法、普通氨水共沉淀法制备BaAl12O19-α六铝酸盐催化剂及其中的Al3+部分被Mn2+取代的BaMnAl11O19-α催化剂,研究了合成方法、Mn2+取代部分Al3+对催化剂晶相结构、比表面积、粒径以及甲烷催化活性的影响。结果表明,反相微乳液法制备的催化剂经1200℃焙烧后更有利于形成六铝酸盐晶相,且具有粒径小、比表面积大、甲烷催化活性高的特点。与BaAl12O19-α相比,BaMnAl11O19-α催化剂具有更高的比表面积(42.87m2/g)和更优异的催化活性,起燃温度T10%为473℃,T90%为668℃。

Effect of Preparation and Mn2+ Substituted on the Crystal Structure and Catalytic Activity of BaAl12O19-αfor Catalytic Combustion of Methane

The catalysts for catalytic combustion of methane,hexa-aluminate BaAl_(12)O_(19-α)and its derivtive,BaMnAl_(11)O_(19-α),in which Mn~(2+) partially substituted for Al~(3+),were prepared by reverse microemulsion mediated NH_4OH coprecipitation and conventional NH_4OH coprecipitation methods.Effects of preparation methods and Mn~(2+) substitution on the phase structure,surface area,diameters of catalysts and catalytic combustion of methane were investigated.The results show that the catalysts prepared by reverse microemulsion mediated NH_4OH coprecipitation forms hexa-aluminate crystal phase more easily when calcined at 1200℃,and has smaller particle size,larger specific surface area and higher catalytic activity than the catalyst prepared by conventional NH_4OH coprecipitation method.Compared to unsubstituted catalyst,Mn~(2+) substituted catalyst had higher specific surface area(42.87m~2/g)and more excellent catalytic activity for methane combustion,and the temperatures at which 10% and 90% methane were converted were 473℃ and 668℃,respectively.