采用铝溶胶作为碳酸铵共沉淀的前驱体,结合乙醇超临界干燥制备了不同金属取代六铝酸盐催化剂(Ba0.8La0.2MAl11O19-α,M=Mn,Fe,Co,Cu),并用BET,XRD,TEM,UV-Vis和O2-TPD等技术对催化剂进行了表征.结果表明,经1200℃焙烧后,生成了具有大的比表面积(42～73 m2·g-1)的棒状六铝酸盐,比表面积由大到小的顺序是Mn＞Co＞Fe＞Cu.XRD结果表明,除Mn取代催化剂之外,其他均含有少量α-Al2O3杂质相.Fe,Mn取代六铝酸盐中的金属离子(Fe3+,Mn3+)主要为Oh配位,而Co,Cu取代六铝酸盐中的金属离子(Co3+,Cu2+)则为Oh和Td配位.O2-TPD表明,Mn,Cu取代的催化剂中具有高的晶格氧含量.催化剂活性由高到低的顺序为Mn＞Cu＞Fe＞Co,催化活性取决于过渡金属离子的氧化还原循环的可逆性、比表面积以及晶格氧等因素.
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