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考察碱土金属氟化物/三氧化二钆在甲烷氧化偶联反应中的催化性能.发现在Gd_2O_3中添加碱土金属氟化物,C_2选择性和收率都有明显提高。当Gd_2O_3摩尔含量相同时,催化性能按Ca-Sr-Ba顺序递增,在80%BaF_2/Gd_2O_3催化剂上C_2选择性和收率分别达59.5%和18.7%.XRD分析结果表明,在含氟催化剂中出现了四方Gd_4O_3F_6新相,其结构与立方CaF_2,SrF_2和BaF_2相似.可能有利于物相之间的匹配及载流子传递.XPS测试发现,催化剂表面上存在着(或O ̄-)物种.与Gd_2O_3相比,在含氟的催化剂中,O_1s结合能较高,表明该吸附氧物种所带电荷较少,对提高C_2选择性有利。
The catalytic performance of alkaline earth metal fluoride / gadolinium oxide in methane oxidative coupling reaction was investigated. It was found that the addition of alkaline earth metal fluoride to Gd 2 O 3 significantly improved the selectivity and yield of C 2. When the molar amount of Gd 2 O 3 is the same, the catalytic performance increases in the order of Ca-Sr-Ba. The selectivity and yield of C 2 on the 80% BaF 2 / Gd 2 O 3 catalyst are 59.5% and 18.7%, respectively. The results of XRD analysis show that the tetragonal Gd_4O_3F_6 new phase appears in the fluorine-containing catalyst, and its structure is similar to the cubic CaF_2, SrF_2 and BaF_2. May be conducive to the match between the phase and carrier transfer. The XPS test found that there are (or O ~ -) species on the surface of the catalyst. Compared with Gd_2O_3, the binding energy of O_1s is higher in the fluorine-containing catalyst, indicating that the oxygen species of the adsorbed oxygen species has less charge and is favorable for increasing the C_2 selectivity.