M-Na-P-Mo-V/SiO2系列催化剂对异丁烯氧化反应的催化性能

 以浸渍法制备了M－Na－P－Mo－V／SiO2系列催化剂，并用FT－IR和TPR对催化剂进行了表征，考察了催化剂上的异丁烯化反应．结果表明，在空速900h－1和345℃的反应条件下，过渡金属的引入可提高甲基丙烯醛的选择性．其中Cu对催化性能的改善最佳，甲基丙烯醛选择性可达65．7％；而在Na－P－Mo－V／SiO2催化剂上，乙酸选择性可达50％，但甲基丙烯醛选性仅为4．1％．在催化剂中引入过渡金属时，Cu在提高甲基丙烯醛选择性的同时，也抑制了完全氧化产物COx的生成；Fe提高双键断裂产物和完全氧化产物选择性的同时，使甲基丙烯醛选择性下降；Zn对反应的影响不很大．TPR结果表明，在入Cu的催化剂中，Cu与杂多酸阴离子之间可能存在“溢流”作用．

Catalytic Performance of M-Na-P-Mo-V/SiO2 Series Catalysts for Isobutylene Oxidation

M Na P Mo V/SiO 2 series catalysts were prepared by impregnation method, and characterized by FT IR and TPR. The isobutylene oxidation on the catalysts was carried out in a continuous flow fixed bed reactor. The results indicated that, owing to the addition of transition metal ions into the catalysts, there is a decrement in activity to a certain extent, but the main products change from acetic acid to methacrolein. The performance of Cu Na P Mo V/SiO 2 catalyst is remarkably improved, providing with selectivity of 65 7% methacrolein and 10 8% acetic acid, while over Na P Mo V/SiO 2 catalyst, the selectivity for acetic acid is as high as 50%. The Cu Na P Mo V/SiO 2 inhibits the total oxidation products, the Fe Na P Mo V/SiO 2 catalyst enhances the selectivity for total fission products, and the Zn Na P Mo V/SiO 2 catalyst has only a little effect on the reaction. TPR experiment showed that the interaction of Cu and heteropoly ions made up the active oxidation reduction centers which corresponds to the reaction results. There may be a "spillover" phenomenon between Cu and heteropoly ions.