Li~+/MgO上乙烷氧化脱氧的活性中心[Li~+O~-]的研究

利用Li+／MgO催化剂上乙烷氧化脱氢制乙烯及IR、TPD等测试手段对外Li+O-]中心的形成机理及其性质进行了研究，表明［Li+O－］中心最初生成与MgO表面的自由羟基相关，气相氧、反应温度配位数等对生成Li＋O－]有一定程度的影响．

Studies on [Li~+O~-]Centers in Oxidation-dehydrogenation of Ethane to Ethene on Li~+/MgO Catalysts

In this paper, the formation mechanism and characterization of Li+O-] centers on Li +/MgO are investigated by the reaction of oxidation-dehydrogenation of ethane to ethene. The concentration of the centers increases with disappearance of free hydroxyl groups ln Li+/MgO. The Li+ entering defect of cations reacts with free hydroxyl to form Li+O-j, for which the mechanism is as follows:They have a positive heat of formation, thus, the concentration of the centers increases with increaslng temperature The process of forming Li+o-] needs to expend surface oxygen,thus, suitable O2(g) is necessary according to the balance of oxygen species over the catalysts, but excessive O2(g) is harmful. The defect of lower coordination numbers affects the formation of Li+O-j, because it affects the existent state of surface Li+.