水含量对醇盐水解制备LaMnAl_(11)O_(19-δ)催化剂结构及其甲烷燃烧性能的影响

Effect of Water Content on the Catalytic Property of LaMnAl_(11)O_(19-δ) for Methane Combustion

采用溶胶凝胶法中的金属醇盐水解技术制备LaMnAl11O19-δ六铝酸盐催化剂,通过X射线衍射、差热-热重、扫描电镜和比表面积分析等实验技术及甲烷燃烧,对催化剂的结构和性质进行了考察。主要考察了金属醇盐水解时加入不同含量的水对催化剂结构以及对甲烷催化燃烧活性的影响。结果表明,催化剂在1200℃焙烧后可以形成完整的六铝酸盐晶型,同时具有较高的催化性能和高温稳定性。水含量对催化剂的性能有较大的影响,水含量较大时催化剂的比表面积和活性明显下降。当水和醇盐的摩尔比为1.5时,所制备的LaMnAl11O19-δ具有较大的比表面积和催化活性。

Manganese-substituted lanthanum hexaaluminates were prepared by sol–gel method from metal alkoxides.The effect of water content in the precursor solution on thermal stability of LaMnAl11O19-δcatalysts was examined by XRD,TG-DTA,SEM and BET analysis.The results showed that the catalyst with good crystallinity was obtained after calcination under oxygen at 1200℃ for 4h..Large water content caused a rapid decrease in the surface area of hexaaluminate.When the molar ratio of H2O to MOR is 1.5,the catalyst retains a high surface area and shows a good activity in CH4 combustion.