直接法合成五氟碘乙烷催化剂RbNO3-KF/C失活

 五氟碘乙烷（C2F5I）不仅可作为全氟烷基碘的初始调聚剂，还可用于生产含氟医药和农药中间体的原料。目前开发了一种新型绿色环保的连续气固相催化合成C2F5I的方法，该法以五氟乙烷和单质碘为原料，以碱金属或碱土金属盐/活性炭为催化剂。本文以活性炭为载体，等体积浸渍法制备了RbNO3-KF/C催化剂。在以五氟乙烷（C2F5H）、碘（I2）为原料，气固相催化合成C2F5I时发现，催化剂活性持续下降。采用BET-BJH、TG-DTA、SEM、XRD、ICP等分析手段对反应前后的催化剂进行分析。结果表明，对于活性组分RbNO3，真正起催化作用的是氧化铷和部分氟化铷；催化过程中积碳的生成导致催化剂的孔道堵塞，使部分活性中心被覆盖以及积碳与烧炭之间的不平衡导致活性组分的流失是催化剂失活的主要原因。

Deactivation of RbNO3-KF/C in the Pentafluoroethyl Iodide Reaction

Pentafluoroethyl iodide(C2F5I) is not only used as the telogens for the telomerization of tetrafluoroethylene to long-chain perfluoroalkyl iodides, but also used as the raw material of intermediate for medicines and agrochemicals. Currently a continuous vapor-phase process for the synthesis of C2F5I has been developed successfully by reacting C2HF5 with I2 in the presence of an alkali or alkaline erath salt supported in activated carbon as catalyst which makes the green production become possible. In this paper, the synthesis of C2F5I via the new novel method was catalyzed by the RbNO3-KF/C catalysts prepared by the equivalent-volume impregnation method. The results indicate that the activity of RbNO3-KF/C catalysts varies continuously with time. By means of BET-BJH, TG-DTA, SEM, XRD, ICP, the deactivation of RbNO3-KF/C catalysts for synthesis of pentfluoroethyl iodide was characterized and compared with the fresh RbNO3-KF/C catalyst. The results indicate that the real active components are RbO and RbF of RbNO3, and the deactivation of the catalytic active component RbNO3-KF/C is mainly caused by the coke-formation on the catalysts during the reaction, and the loss of active components due to the imbalance between carbon deposition and carbon baking.