Abstract: Hydrofluorocarbons have excellent characteristics of environmental friendliness, low toxicity, high stability, and are widely used in many fields, especially in the refrigeration industry, which has attracted great attention. Hydrofluorocarbons usually need to be prepared by hydrogenation of fluorinated olefins. However, due to the strong electronegativity of fluorine atoms, it is difficult to activate perfluoroalkenes, leading to perfluoroalkene hydrogenation is a challenging problem. For the hydrogenation reaction of perfluoroalkenes, precious metal supported palladium catalysts are currently widely used internationally, with a large palladium loading capacity and high cost. In this work, a high activity and low loading palladium catalyst with only 0.1wt% palladium content was prepared by impregnation method, and a series of copper promoted palladium catalysts were also prepared. The performance of different catalysts in the hydrogenation of hexafluoropropylene dimer were investigated on a micro fixed bed continuous reactor. The results showed that the 0.1wt% Pd catalyst also had good activity, the conversion of hexafluoropropylene dimer was 49.3%, and the selectivity of the target product was 97.6%. When 10wt% Cu promoter was used, the catalyst had the best activity, the conversion of hexafluoropropylene dimer was higher than 93.4%, and the selectivity of the target product could reach 98.6%. Through the characterization and analysis of XRD, H2-TPR, and XAFS technologies, it was found that the copper in the catalyst mainly existed in the form of Cu2O and Cu0. Cu2O could form a strong interaction with Pd, greatly reduced the reduction temperature of Cu2O in the catalyst through hydrogen overflow, and the hydrogen atoms overflowing from palladium could greatly improve the hydrogenation activity of hexafluoropropylene dimer. Therefore, this work provides a highly active, low-content and stable palladium-based catalyst for perfluoroolefin hydrogenation reaction and its preparation method, which provides a research direction for further design of efficient catalysts.

Key words: hexafluoropropylene dimer, dodecafluorohexane, catalytic hydrogenation, Pd-Cu/Al2O3 catalyst, bimetallic catalyst

摘要： 氢氟烃具有环境友好、低毒、稳定性高等优良特性，在众多领域得到广泛应用，特别是在制冷行业引起了极大地重视。氢氟烃可以通过全氟烯烃加氢反应进行制备，然而，由于氟原子的电负性强，难以活化全氟烯烃中的碳碳双键，因此全氟烯烃加氢反应是一个具有挑战性的难题。针对全氟烯烃加氢反应，目前国际上基本使用贵金属负载钯催化剂，钯负载量较大，成本较高。本工作采用浸渍法制备了钯含量仅为0.1wt%的高活性低负载量钯催化剂，以及一系列铜为助剂的负载钯催化剂，在微型固定床连续反应器上考察了不同催化剂催化六氟丙烯二聚体加氢反应的性能。结果表明，制备的0.1wt%负载量钯催化剂也具有较好的活性，原料转化率为49.3%，目标产物选择性可达97.6%；使用10wt% Cu助剂时催化剂活性最高，原料转化率高于93.4%，目标产物选择性可达98.6%。通过XRD, H2-TPR和XAFS等技术表征分析，发现催化剂中铜主要以Cu2O和Cu0形式存在，Cu2O可以和Pd形成强相互作用，通过氢溢流形式极大地降低催化剂中Cu2O的还原温度，从钯中溢流出的氢原子可以极大地提高六氟丙烯二聚体加氢反应活性。因此，本工作提供了一种全氟烯烃加氢反应高活性、低含量且较稳定的钯基催化剂的制备方法，为进一步设计高效催化剂提供了研究方向。

关键词: 六氟丙烯二聚体, 十二氟己烷, 催化加氢反应, Pd-Cu/Al2O3催化剂, 双金属催化剂