反相微乳法合成稀土六铝酸盐催化剂及其表征  

Synthesis and Characterization of Rare-earth Hexaaluminate Catalysts Prepared by Reverse Microemulsion Method

作　　者：张晓红[1] 胡瑞生[1] 李玉芬[1] 李常艳[1] 

机构地区：[1]内蒙古大学化学化工学院,稀土材料重点实验室,呼和浩特010021

出　　处：《应用化学》2005年第11期1178-1181,共4页Chinese Journal of Applied Chemistry

基　　金：国家自然科学基金(20163001);内蒙古自然科学基金(200408020203);OSSO国家重点实验室资助项目

摘　　要：在水/Triton X-100/环己烷/正丁醇微乳体系中合成了单相铁取代的稀土六铝酸镧催化剂,与非取代型六铝酸镧和钴取代的六铝酸镧催化剂进行比较,以CH4催化燃烧反应为探针反应对其进行催化活性的测试,并用XRD、TPR、BET测试技术对其合成的样品进行物理化学性质的表征。XRD和TPR实验结果表明,在该微乳体系中得到的产物经过1 400℃高温焙烧3 h后均可制备出主相结构为相应六铝酸盐的催化剂,掺杂铁元素的六铝酸盐的催化剂易形成LaFeA l11O19单相结构。掺杂钴和未掺杂钴的催化剂除了有主相结构LaCoA l11O19和La2A l24.4O39.6相外还伴有少量的稀土钙钛矿LaA lO3相,掺杂铁和掺杂钴的样品均在700℃以前达到甲烷有50%的转化,800℃完全转化,甲烷催化活性均明显好于未掺杂过渡元素金属的样品。但掺杂铁的样品在700℃以内的活性好于掺杂钴的样品,700℃以后活性基本相当。The Fe-doped, Co-doped and no-doped hexaaluminate catalysts were prepared by the reverse microemulsion method in the system of water/Triton X-100/n-butoanol/cyclohexane. The effects of doping elements on phase, specific surface area and activity for methane combustion were investigated by means of XRD, BET, H2-TPR. The XRD and TPR results indicate that a single phase LaFeAl11O19 hexaaluminate was formed according to the XRD spectrum of Fe-doped hexaaluminate catalyst, but XRD spectrum analyses of Co-doped and no-doped catalysts indicated that hexaaluminate was dominated phase and accompanied with a few perovskite phase when calcined at 1 400 ℃ for 3 h. H2-TPR patterns of the Fe-doped and Co-doped catalysts show that the reduction peaks appear in the range of 400 ℃ and 800 ℃, while no reduction peaks appear for no-doped catalyst. Reverse microemulsion method is beneficial to maintaining high surface area. The specific surface areas of prepared catalysts are about 11.6-16.3 m^2/g. Compared with no-doped catalyst, the high-temperature activity of Fe-doped and Co-doped catalysts increased obviously, which made methane conversion 50% below 700 ℃ and methane complete conversion temperature was 800 ℃. However, the high-temperature activity of Fe-doped catalyst is better than that of Co-doped catalyst within 700 ℃, and their high-temperature activities are almost the same over 700 ℃. Fe-doped catalyst formed a single phase of hexaaluminate LaFeAl11O19 and had a higher activity for methane combustion. It might be a candidate for catalytic gas turbine combustor.

关 键 词：反相微乳法 甲烷 六铝酸盐 过渡金属 稀土 

分 类 号：O643.1[理学—物理化学]