La促进型六铝酸盐Ba1－xLaxFeAl11O19－δ催化甲烷燃烧性能

用碳酸铵水溶液共沉淀法制备了系列Ba_1－xLa_xFeAl₁₁O_19－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Ba_0.2La_0.8FeAl₁₁O_19－δ,其催化甲烷燃烧的起燃温度仅有495 ℃（V_CH4:V_O2:V_N2=1:4:95）.XRD和SEM结果表明,不同含量镧掺杂的材料经1 200 ℃焙烧5 h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.Diffuse UV-Vis表征表明催化剂中的铁呈＋3价,Diffuse UV-Vis, TPR和FT-IR结果表明Ba、La、Fe之间存在协同作用.

Effects of La Incorporation in Ba1- xLaxFeAl11O19-δon the Performance of Methane Catalytic Combustion

Series of Ba1－xLaxFeAl11O19－δ hexaaluminate 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－δ hexaaluminate, 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.