Qu Enhui, Luo Jingjie, Di Xin, Li Chuang, Liang Changhai
Laboratory of Advanced Materials & Catalytic Engineering, School of Petroleum and Chemical Engineering, Dalian University of Technology, Panjin 124221, China.
Laboratory of Advanced Materials & Catalytic Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China.
J Nanosci Nanotechnol. 2020 Feb 1;20(2):1140-1147. doi: 10.1166/jnn.2020.16965.
The fabrication of bimetallic catalysts has been taken great focus in the concept of heterogeneous catalysis due to their high efficiency and economic concerns. In this work, a series of bimetallic Ru-Re catalysts were designed and synthesized for the selective hydrogenation of dimethyl terephthalate (DMT) to 1,4-cyclohexane dicarboxylate (DMCD) under mild condition. Characterization techniques including the XRD, TEM, STEM-HAADF EDX elemental mapping, H2-TPR, and XPS were used to study the surface chemical property, the morphology, as well as the catalytic behavior of different samples. It was revealed that the monometallic Ru catalyst already has the capacity to activate and transform DMT into DMCD. Whilst the promotion effect can be optimized to a maximum with only small amount of Re, with the mass ratio of Ru/Re as 10:1. It was also revealed that the addition of Re could largely enhance the distribution of surface active metal species, facilitate the charge transfer between Ru and Re, as well as strengthen the Ru-Re synergistic interaction, which further led to the modification of the redox ability and the catalytic performances of samples. However, excessive addition of Re caused strong interaction between Ru and Re, and further limited the H₂ activation and the seasonable release of the active reducible metal species, which was responsible for the depressed catalytic performances in the presence of higher Re loading. The RuRe/AC catalyst displayed the DMT conversion of 82% with DMCD selectivity of 96% under mild condition of 70 °C at 3 MPa. The specific rate of RuRe/AC based on per gram of Ru was 0.44 mol·g Ru·h.
由于双金属催化剂具有高效率且符合经济需求，因此在多相催化概念中备受关注。在本工作中，设计并合成了一系列双金属Ru-Re催化剂，用于在温和条件下将对苯二甲酸二甲酯（DMT）选择性加氢为1,4-环己烷二甲酸酯（DMCD）。采用XRD、TEM、STEM-HAADF EDX元素映射、H₂-TPR和XPS等表征技术研究了不同样品的表面化学性质、形貌以及催化行为。结果表明，单金属Ru催化剂已经具有将DMT活化并转化为DMCD的能力。而仅加入少量Re（Ru/Re质量比为10:1）就能将促进效果优化至最大。还发现加入Re可大大增强表面活性金属物种的分布，促进Ru与Re之间的电荷转移，并加强Ru-Re协同相互作用，进而导致样品的氧化还原能力和催化性能发生改变。然而，过量加入Re会导致Ru与Re之间的强相互作用，进一步限制H₂活化以及活性可还原金属物种的适时释放，这就是在较高Re负载量下催化性能下降的原因。RuRe/AC催化剂在70℃、3MPa的温和条件下表现出82%的DMT转化率和96%的DMCD选择性。基于每克Ru的RuRe/AC的比速率为0.44 mol·g Ru·h。
