摘要
采用等体积浸渍法制备了La改性的Mn/Al2O3催化剂。以甲烷燃烧反应为探针反应,考察了La2O3的引入方法对其催化活性的影响。催化剂的物化性质经TPR,XRD和XPS表征。研究结果表明,La的添加顺序对催化剂的物化性质和催化活性有显著影响。在以共浸渍方式制备的催化剂A中,载体与锰物种之间的相互作用大受削弱,锰晶粒变小,分散度增加,催化剂的活性显著提高,甲烷转化率为50%,对应的反应温度比未加La时降低了90℃。在先浸La后浸Mn制备的催化剂C中,La的存在也使催化剂的催化活性大大改善,效果与催化剂A相当。当以先浸Mn后浸La的方式加入助剂时,催化剂B的比表面积降低,催化活性下降。
A series of Mn/Al2O3 catalysts promoted by lanthanum were prepared by the incipient wetness co-impregnation and sequential impregnation methods. The effect of La2O3 introducing methods on the catalytic activity of Mn/Al2O3 in methane catalytic combustion were investigated. The properties of catalysts were characterized by TPR, XRD and XPS. The results showed that the catalytic activity and the properties were affected significantly by La2O3 introducing methods. Catalyst A was pre- pared by the La-Mn co-impregnation method in which the interaction between manganese and support was obviously weakened, the particle size of manganese crystallites was significantly reduced, and manganese species were well dispersed. The catalytic performances of A in methane combustion exhibited that manganese species were easier reduced, and the temperature corresponding to 50% methane conversion was decreased by 90℃ compared with the sample without lanthanum. Catalyst C which La component was firstly impregnated on support before manganese had similar catalytic performances as A. When La component was impregnated after manganese, the active area was decreased, resulting in the decrease of catalyst activity.
出处
《合成化学》
CAS
CSCD
2008年第2期162-165,共4页
Chinese Journal of Synthetic Chemistry
基金
教育部新世纪人才支持计划资助项目(NCET-05-0783)
关键词
锰基催化剂
镧助剂
催化活性
甲烷
manganese-based catalyst
lanthanum promoter
catalytic activity
methane
