碱土金属氟化物促进Eu_2O_3催化剂的甲烷氧化偶联性能

Catalytic Performance for Oxidative Coupling of Methane Over Eu 2O 3 Catalysts Promoted by Alkaline Earth Fluorides

考察了碱土金属氟化物促进的Ｅｕ２Ｏ３在甲烷氧化偶联反应中的催化性能。发现在Ｅｕ２Ｏ３中添加碱土金属氟化物后，碳二烃（Ｃ２）的选择性和收率都有明显提高。当Ｅｕ２Ｏ３摩尔含量相同时，催化性能按ＣａＦ２Ｅｕ２Ｏ３≈ＢａＦ２Ｅｕ２Ｏ３＜ＳｒＦ２Ｅｕ２Ｏ３顺序递增。ＸＲＤ分析结果表明，在新鲜的ＢａＦ２Ｅｕ２Ｏ３催化剂中出现了菱形ＥｕＯＦ新相，而在其它两类催化剂中氟氧离子交换不明显，这种差异与碱土金属氟化物中阳离子半径的差别有关。吡啶（Ｐｙ）和ＣＯ２ＴＰＤ测试表明，Ｅｕ２Ｏ３中添加ＳｒＦ２后，表面酸性减弱，碱强度稍有增加，有利于Ｃ２选择性的提高。

The catalytic performance of oxidative coupling of methane(OCM) over Eu 2O 3 catalysts promoted by alkaline earth fluorides was studied. The results showed that C 2 hydrocarbon selectivity and yield over the fluoride promoted Eu 2O 3 catalysts were apparently higher than those of pure Eu 2O 3. The OCM performance increased according to the sequence of CaF 2 Eu 2O 3≈BaF 2 Eu 2O 3<SrF 2 Eu 2O 3 under the same conditions. X ray diffraction experiment indicated that rhombohedral EuOF phase formed in the fresh BaF 2 Eu 2O 3 catalyst, while the exchange of F - and O 2 did not apparently happen in the fresh CaF 2 Eu 2O 3 and SrF 2 Eu 2O 3 catalysts. Pyridine TPD measurements showed that, after adding SrF 2 to Eu 2O 3, the catalyst surface acidity decreased, whereas the surface basic strength increased slightly, resulting in an improvement in C 2 selectivity and yield.