六氟丙烯气相环氧化反应诱导期及CuO/SiO_(2)催化剂失活机理

The induction period and inactivation of CuO/SiO_(2) for gas-phase epoxidation of hexafluoropropylene

铜基催化剂在催化烯烃环氧化反应上具有优异的催化性能和广阔的应用前景。目前,已有专利将负载型铜基催化剂应用于六氟丙烯(HFP)气相环氧化反应,并且表现出优异的催化性能,但是反应存在诱导期及催化剂在后期活性明显降低等问题,限制了其进一步的应用发展。通过等体积浸渍法制备CuO/SiO_(2)催化剂,并通过FT-IR、XRD、TEM和TG等对CuO/SiO_(2)催化剂的物理-化学性质进行分析,系统研究其在HFP气相环氧化反应中存在诱导期及失活的原因。结果表明,Cu-F物种是反应的活性中心,而该物种由原料气(空气与HFP)和CuO反应才能产生,这是反应过程中产生诱导期的原因所在;而反应后Cu颗粒的聚集长大是催化剂活性降低的主要原因。

Copper-based catalysts have excellent catalytic performance and broad application prospects in catalyzing olefin epoxidation reactions.At present,there is already a patent applied the supported copper-based catalyst to the gas-phase epoxidation reaction of hexafluoropropylene,and shows excellent catalytic performance.However,the induction period of the reaction and the significantly reduced activity of the catalyst in the later stage limit its further application and development.Therefore,in this paper,CuO/SiO_(2)catalysts were prepared by the incipient wetness impregnation method.And the physico-chemical properties of CuO/SiO_(2)catalysts were analyzed by characterization methods such as FT-IR,XRD,TEM and TG,and the reasons for induction period and inactivation in gas-phase epoxidation reactions of hexafluoropropylene were systematically studied.The results showed that Cu-F species were the active center of the reaction,and the species were produced by the reaction of raw gas(air and HFP)and CuO,which led to the emergence of the induction period.The main reason for the decrease in catalyst activity in the later stage of the reaction is the aggregation and growth of Cu particles.