摘要
首先制备了一系列的单元(Ce O2,Ti O2,Zr O2)、双元(Ce-Ti,Ti-Zr)和三元(Ce-Ti-Zr)载体,然后通过浸渍法在载体表面负载Co,考察了载体组成和焙烧温度对该催化剂的甲烷部分氧化(POM)催化性能的影响。利用N2物理吸附、X射线粉末衍射、H2-程序升温还原、扫描电子显微镜和热重分析等手段对反应前后催化剂的物理化学性质进行了表征。实验结果表明,载Co催化剂的催化性能按三元>双元>单元的顺序依次降低。700℃焙烧制备的Co/Ce-Ti-Zr-700三元载体催化剂表现出最高的CH4转化率和H2、CO的选择性,同时该催化剂具有较高的稳定性。在Ce-Ti-Zr三元载体催化剂中,Ce O2-Ti O2-Zr O2之间产生了较强的相互作用,从而抑制了非活性相Co Ti O3的生成,产生了更多的活性中心;同时这种载体之间的作用可以防止催化剂在反应过程中发生相变生成Co Zr2和Zr C之类的物质。
A series of single （CeO2, TiO2, ZrO2）, binary （Ce-Ti, Ti-Zr） and ternary （Ce-Ti-Zr） composite supports were synthetized to prepare cobalt containing catalysts for the partial oxidation of methane. The catalysts were then obtained by impregnation method using the as-synthesized supports. The effects of support composition and calcination temperature on the catalytic performance of the catalysts in partial oxidation of methane （POM） were investigated. The fresh and used catalysts were characterized by physicochemical characterization methods such as N2 physical adsorption, X-ray diffraction （XRD）, H2-temperature programmed reduction （TPR）, scanning electron microscopy （SEM） and therrnogravimetry （TG）. Experimental results show that the performance of the cobalt-based catalysts decreases according to the following orders： ternary 〉 binary 〉 single. Co/Ce-Ti-Zr-700 catalyst calcined at 700℃ exhibites the highest CH4 conversion and selectivity to CO and H2, as well as the best stability. The strong interactions between CeO2, TiO2, and ZrO2 in the ternary support effectively restrain the formation of non-active phase of CoTiO3 and promote the formation of active sites. Furthermore, during the POM reaction, the interactions can inhibit the phase transformation of catalyst to generate the non-active phase of CoZr2 or ZrC.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2014年第6期1286-1293,共8页
Journal of Chemical Engineering of Chinese Universities
基金
国家自然科学基金(21067004
21263005)
江西省自然科学基金青年科学基金计划(20133BAB21003)
江西省教育厅高等学校科技落地计划项目(KJLD14046)
江西省青年科学家培养项目(20122BCB23015)
关键词
复合载体
钴
甲烷部分氧化
铈锆固溶体
composite support
cobalt
partial oxidation of methane
ceria-zirconia solid solution
