搀杂六铝酸盐LaM_xAl_(12-x)O_(19+δ)上甲烷催化燃烧研究

Study on Methane Catalytic Combustion of Mn Doped LaMn_xAl_(12-x)O_(19+σ) Hexaaluminate Catalysts

采用共沉淀法制备了系列金属Mn搀杂的六铝酸盐LaMnxAl12-xO19+δ(x分别为0,0.5,1.0,1.5,2.0,5.0)催化剂,采用BET,TG DTA,XRD进行了物性表征,并以甲烷催化燃烧为目标反应,研究了Mn搀杂量对催化剂活性的影响。结果表明:LaAl12O19+δ催化活性较低,随着Mn的引入,催化活性逐步提高。当x=1.5时,催化活性达到最大值,为理想搀杂量。焙烧温度对晶型及催化活性有重要影响,1200℃时可以形成完整的六铝酸盐晶型,并具较高的催化性能。所得较好催化剂起燃温度T10%为418℃,T90%为663℃。

Series of hexaaluminates LaMn_xAl_(12-x)O_(19+σ) doped with Mn (Here x is 0, 0.5, 1.0, 1.5, 2.0, 5.0 respectively) were synthesized by co-precipitation method, and the physico-chemical properties were characterized by means of BET, TG-DTA, and XRD techniques. Effect of Mn doped content on methane combustion catalytic activity was also studied. It shows that catalytic activity of LaAl_(12)O_(19+σ) is low, catalyst activity is enhanced gradually with the introduction of Mn, and when doped Mn content reached 1.5, namely x=1.5, the activity is up to peak. The crystal phase and activity are greatly affected by cacination temperature, and full hexaaluminates with good activity were formed when catalysts cacinated at 1200 ℃ for 4 h. The best performances of the samples are that light-off T_(10%) is 418 ℃, and conversion T_(90%) is 663 ℃.