Synthesis And Catalytic Study Of La₂B₂O₇(B=Zr,Ce,Sn) Composite Oxide

The catalytic combustion of methane and the methane reforming with carbon dioxides are two effective ways of make use of the methane. Because of the chemical stability of the methane, both methane reforming and methane combustion reaction need high temperature condition, which requires not only high catalytic activity but high thermal stability catalyst, in this regard, this paper choose the pyrochlore type composite oxide, which has high thermal stability , mainly synthesize the La₂B₂O₇(B= Zr, Ce, Sn) composite oxides, and characterize the physical chemical properties and catalytic performance by means of BET, XRD, TPR, TG, XPS and the catalytic activity evaluation etc..The studies show, calcinations at 900°C for 3h in the air, the La₂Zr₂O₇ and La₂Sn₂O₇ produce single-phase pyrochlore-type oxides and La₂Ce₂O_7-δ form single-phase fluorite-type oxide. Because of crystal phase structure, reduction performance and high surface area, the La₂Zr₂O₇ show excellence catalytic activity for both methane reforming and methane combustion reaction. Particularly in the methane reforming with carbon dioxide reaction, the single-phase pyrochlore-type La₂Zr₂O₇ also show good catalytic activity. After modified with Ni, the catalytic activity of Ni-La₂Zr₂0₇ increases notably. Under the reaction condition, the both conversion rates of C0₂ and CH₄ can reach 95%, with high selectivities for H₂ and CO.