Huang Xin, Li Haitao, Zhang Yin, Wu Ruifang, Ban Lijun, Xi Lin, Yin Zhifang, Peng Jian, Zhao Yongxiang, Fang Li
Engineering Research Center of Ministry of Education for Fine Chemicals, Shanxi University, Taiyuan 030006, China.
School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
Nanoscale. 2022 Sep 22;14(36):13248-13260. doi: 10.1039/d2nr02407a.
In conventional thermocatalytic reactions under a reducing atmosphere, stabilization of the active Cu component and inhibition of over-reduction into metallic Cu are extremely challenging. In this study, Au@CuO core-shell nano-catalysts with different CuO shell thicknesses were synthesized, and the effect of the Au nano-core on Cu stability under a reducing atmosphere and the catalytic performance of Cu in the ethynylation of formaldehyde were investigated. The Au nano-core facilitates CuO dispersion and leads to an increase of 0.2-0.5 eV in electron binding energies of CuO and CuC in the range of 27-55 nm, attributed to the long-range electromagnetic effect of Au NPs. Specifically, active Cu centers exhibit high stability under a reducing atmosphere due to the long-range electromagnetic effect of the Au nano-core. In the ethynylation of formaldehyde as a probe reaction, Cu/(Cu + Cu) on Au@CuO catalysts remained at 88-91%. The catalytic performance in the ethynylation of formaldehyde revealed that the introduction of an Au nano-core into Cu-based catalysts increased the TOF from 0.37 to 0.7 h, and decreased the activation energy from 42.6 to 38.1 kJ mol. Additionally, the Cu/(Cu + Cu) ratios and the catalytic performance in the ethynylation of formaldehyde (BD yield = 65%, BD selectivity = 95%) on Au@CuO catalysts remained constant after nine cycles, while pure CuO readily deactivated due to the dramatically reduced Cu/(Cu + Cu) ratios and carbyne deposition. In summary, Cu in Cu-based catalysts showed high catalytic activity and stability during the ethynylation of formaldehyde due to the long-range electromagnetic effect of the Au nano-core.
在还原气氛下的传统热催化反应中，活性铜组分的稳定化以及抑制其过度还原为金属铜极具挑战性。在本研究中，合成了具有不同氧化铜壳层厚度的金@氧化铜核壳纳米催化剂，并研究了金纳米核在还原气氛下对铜稳定性的影响以及铜在甲醛乙炔化反应中的催化性能。金纳米核促进了氧化铜的分散，并使27 - 55纳米范围内氧化铜和碳化铜的电子结合能增加了0.2 - 0.5电子伏特，这归因于金纳米颗粒的远程电磁效应。具体而言，由于金纳米核的远程电磁效应，活性铜中心在还原气氛下表现出高稳定性。在作为探针反应的甲醛乙炔化反应中，金@氧化铜催化剂上的铜/(铜 + 铜)保持在88 - 91%。甲醛乙炔化反应的催化性能表明，在铜基催化剂中引入金纳米核使转化频率从0.37提高到0.7小时，并使活化能从42.6降低到38.1千焦/摩尔。此外，经过九个循环后，金@氧化铜催化剂上的铜/(铜 + 铜)比率以及甲醛乙炔化反应中的催化性能（1,3 - 丁二烯产率 = 65%，1,3 - 丁二烯选择性 = 95%）保持恒定，而纯氧化铜由于铜/(铜 + 铜)比率急剧降低和卡宾沉积而容易失活。总之，由于金纳米核的远程电磁效应，铜基催化剂中的铜在甲醛乙炔化反应中表现出高催化活性和稳定性。
