氯化稀土改性Ag/CaCO_3催化剂对丙烯环氧化反应的影响

Epoxidation of Propylene on Ag/CaCO_3 Catalysts Modified by Rare Earth Chloride

本文对用氯化稀土改性 Ag/ Ca CO3催化剂催化丙烯直接环氧化反应进行了研究 ,实验结果表明 :加入改性剂后 ,催化剂活性大幅度降低 ,但其对环氧丙烷 (PO)的选择性明显增加 ,总的对 PO的收率提高。催化剂的活性、选择性与催化剂的组成、反应温度、接触时间以及原料组成有很大关系。在富氧和富烯原料气中 ,催化剂的催化性能截然不同 ,在富氧原料气中由于在催化剂表面易形成氯化银而使催化剂对 PO的选择性随反应时间急剧下降 ;在富烯原料气中进行反应则随反应时间变化不大。

Epoxidation of propylene over rare earth chloride doped silver catalysts were performed at atmospheric pressure using conventional flow reactors.Although the stationary activity was somewhat low after modification,each type of catalyst has improved the selectivity to PO.The selectivity and activity was dependent on reaction temperature,contact time and catalyst composition.Under oxygen rich atmosphere,the marked drop in selectivity to PO was observed.In exposing the catalysts to a stream of hydrogen or inert gas,the catalysts restored the initial selectivity to PO.The reason of decreased selectivity to PO is due to the formation of silver chloride.