不同金属取代六铝酸盐的制备及其对甲烷燃烧的催化性能研究  

Preparation of Different Metal Substituted Hexaaluminate and Its Catalytic Performance of Methane Combustion

作　　者：李顺清[1] 邹国军[1] 王晓来[1] 

机构地区：[1]中国科学院兰州化学物理研究所羰基合成与选择氧化国家重点实验室

出　　处：《中国稀土学报》2006年第5期523-527,共5页Journal of the Chinese Society of Rare Earths

摘　　要：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（Ba0.8 Lao.2 MAI11 O19-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（42-73m^2·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（Fe^3＋，Mn^3＋）主要为Oh配位，而Co，Cu取代六铝酸盐中的金属离子（Co^3＋，Cu^2＋）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。Abstract： Different metal substituted hexaaluminate catalysts （Ba0.8 La0.2 MAl11 O19-α） were the M = Mn, Fe, Co, Cu were prepared using alumina sol as the （NH4）2CO3 coprecipitation precursor and supercritical drying （SCD） method. Meanwhile the catalysts were characterized using BET, XRD, TEM, UV-Vis-DR and O2-TPD techniques. The rod-like hexaaluminate nanoparticles with high surface area ranging from 42 to 73 m^2·g^-l were obtained after calcinations at 1200 ℃. The XRD results reveal that the main crystal phase of the catalyst is hexaaluminate and smallamount of α-Al2O3 existed except for Bao.8 La0.2 MnAl11 O19-α catalyst. Moreover, the UV-Vis-DR results verify that Fe^3＋ , Mn^3 ＋ occupy the Oh sites in the hexaaluminate structure while Co^3＋, Cu^2 ＋ locate at the Oh and Td sites. O2-TPD results show that the Mn and Cu substituted hexaaluminate possesses high lattice oxygen content. The descending sequence of the activity is Mn 〉 Cu 〉 Fe 〉 Co, and the activity is affected by reversibility of the reduction/oxidation cycle between M^n＋ and M^（n-1）, surface area and lattice oxygen etc.

关 键 词：甲烷 催化燃烧 六铝酸盐 超临界干燥 稀土 

分 类 号：TQ203[化学工程—有机化工] O643.3[理学—物理化学]