La促进型六铝酸盐Ba_(1-x)La_xFeAl_(11)O_(19-δ)催化甲烷燃烧性能

Effects of La Incorporation in Ba_(1-x)La_xFeAl_(11)O_(19-δ) on the Performance of Methane Catalytic Combustion

用碳酸铵水溶液共沉淀法制备了系列Ba1-xLaxFeAl11O19-δ六铝酸盐型催化剂,并以甲烷燃烧为探针反应考察催化剂的催化活性.La部分取代Ba提高了催化剂的催化甲烷燃烧活性,且随La取代量的增加,催化剂的起燃温度呈规律性变化,镧、钡之间存在最佳配比,活性最好的催化剂为Ba0.2La0.8FeAl11O19-δ,其催化甲烷燃烧的起燃温度仅有495℃(VCH4:VO2:VN2=1:4:95).XRD和SEM结果表明,不同含量镧掺杂的材料经1200℃焙烧5h后,呈现典型的六铝酸盐结构特征;不同温度的焙烧实验表明掺杂镧能够促进六铝酸盐相的形成.DiffuseUV-Vis表征表明催化剂中的铁呈+3价,DiffuseUV-Vis,TPR和FT-IR结果表明Ba、La、Fe之间存在协同作用.

Series of Ba1-xLaxFeAl11O19-δhexaaluminate catalysts were prepared by (NH4)2CO3 co precipitation method and their performance for methane catalytic combustion was studied.The obtained materials were characterized by XRD,Diffuse UV Vis,FT IR,TPR,and N2 BET techniques.The results showed that partial substitution of Ba with La in Fe hexaaluminates could enhance catalytic activity for methane combustion,and the optimal catalyst was Ba0.2La0.8FeAl11O19-δhexaaluminate,whose light off temperature was as low as 495 ℃denoted by 10%conversion of methane (VCH4/VO2/VN2=1/4/95).XRD and SEM characterization indicated that the samples formed well defined hexaaluminate phase after calcination at 1 200 ℃for 5 h,and the dopant of La could promote the formation of hexaaluminate phases.UV Vis DR characterization revealed that the oxide state of Fe is +3 in Ba1-xLaxFeAl11O19-δcatalysts.The synergism between Ba,La and Fe was observed based on the results of UV Vis DR,FT IR and TPR.