La_(0.8)Sr_(0.2)Fe_(1-x)Sc_xO_(3-δ)催化剂的制备、表征及甲烷催化燃烧性能

Preparation,Characterization and Catalytic Activities of La_(0.8)Sr_(0.2)Fe_(1-x)Sc_xO_(3-δ) Catalysts for Methane Combustion

采用甘氨酸-硝酸盐溶液燃烧法制备了钙钛矿型氧化物催化剂La0.8Sr0.2Fe1-xScxO3-δ(LSFS,x=0,0.3,0.4,0.5,0.6,0.8,1),利用X射线衍射(XRD)、H2程序升温还原(H2-TPR)、扫描电子显微镜(SEM)和比表面积测试等手段对催化剂进行了系统表征,并在常压微型固定床反应器上考察了催化剂对甲烷燃烧的催化性能.结果表明,经空气气氛下900℃煅烧5h制备的LSFS均具有单一的钙钛矿结构,在La0.8Sr0.2FeO3-δ(LSF)中掺杂Sc有助于改善催化剂的抗烧结性能,提高催化剂的比表面积.当LSF中的Sc掺杂量为0.4-0.6时,所形成的LSFS表现出良好的甲烷催化燃烧活性,其中Sc掺杂量为0.5时,其起燃温度(T10)和完全转化温度(T90)分别为406和563℃,与La0.8Sr0.2FeO3-δ和La0.8Sr0.2ScO3-δ相比,T10分别降低了14和87℃;T90分别降低了59和95℃.

Perovskite-type La0.8Sr0.2Fe1-xScxO3-δ （LSFS, x=0, 0.3, 0.4, 0.5, 0.6, 0.8, 1） catalysts were prepared by glycine-nitrate solution combustion. The catalysts were characterized by X-ray powder diffraction （XRD）, H2-temperature-programmed reduction （H2-TPR）, scanning electron microscopy （SEM）, and specific surface area measurements. The catalytic performance of LSFS for methane combustion was investigated in a micro fixed-bed reactor. The results showed that all the LSFS catalysts have a single perovskite structure after calcining in air at 900℃ for 5 h. By doping Sc into La0.8Sr0.2Fe1-xScxO3-δ, the sintering agglomeration between the LSFS particles is weakened, and therefore the specific surface area is increased. At Sc dopings of 0.4-0.6, the resultant LSFS gives good catalytic activity for methane combustion, with a light-off temperature （T10） of 406℃ and a total conversion temperature （T70） of 563℃ at a Sc doping of 0.5. Compared with LaosSro.2FeO3, and La08Sr02ScO3, the Tlo is decreased by 14 and 87 ℃, and 7＂90 is decreased by 59 and 95℃, respectively.