【摘要】 以甲烷催化燃烧为目标反应,分别采用了碳酸铵和氨水为沉淀剂的共沉淀法制备了Mn取代的镧六铝酸盐催化剂。在不同的焙烧温度下通过物相分析,确定了最佳焙烧温度。用BET、XRD进行了物性表征,研究了沉淀剂的种类和沉淀温度对所制备催化剂的化学结构及甲烷催化燃烧活性的影响,最后考察了不同碳酸铵加入量下所得催化剂性能。结果表明:在1200℃左右焙烧4h可以形成完整的六铝酸盐晶型。氨水做沉淀剂在不同温度下所制备的催化剂从比表面积和活性上来看均不如碳酸铵所得催化剂。当沉淀温度为90℃、n(碳酸铵)/n(M2+)(其中M2+为带两个正电荷的金属离子)1.5时,所得催化剂的活性最高,起燃温度T10%为471℃,完全转化温度T90%为662℃。更多还原

【Abstract】 The co-precipitation method was employed to prepare LaMnAl_ 11 O_ 19-δ catalyst for methane combustion by using ammonia and salvolatile as precipitator. It was studied to determine the optimal cacination temperature by analysing the physical phase of catalyst under various cacination temperature. The influences of precipitator and precipitation temperature on the chemical structure and catalytic activity for methane combustion over them were investigated by means of XRD and BET techniques. The effects of amounts salvolatile added on catalysts were investigated. The results show that the full crystal phase of hex-aluminates with good activity were formed when catalysts were cacinated at 1200℃ for 4 h. Salvolatile as precipitator was better than ammonia in the process of co-precipitation. Under the precipitation temperature of 90℃ and the n (salvolatile)/n(M~ 2+ )of 1.5, the catalyst had high activity and its light-off T_ 10% was 432℃, total conversion T_ 90% was 662℃。更多还原