Cu/ZnO催化剂的金属载体相互作用及其对糠醛加氢制糠醇反应性能的影响

Effect of the metal-support interaction in the Cu/ZnO catalyst on its performance in the hydrogenation of furfural to furfuryl alcohol

  • 摘要: 采用共沉淀法制备了系列Cu/Zn比不同的Cu/ZnO催化剂,研究了Cu/Zn比与金属载体强相互作用(SMSI)的关系及其对糠醛气相加氢制糠醇催化反应性能的影响。XRD、H2-TPR、SEM、HRTEM和XPS等表征结果显示,Cu/ZnO催化剂中的金属载体强相互作用改变了催化剂的微观结构。ZnO载体对活性金属Cu颗粒具有不同程度的几何修饰,影响了Cu表面的电子状态。不同Cu/Zn比的Cu/ZnO催化剂的SMSI作用顺序为:20Cu/ZnO > 40Cu/ZnO > 60Cu/ZnO > 80Cu/ZnO。在同一反应条件下,20Cu/ZnO催化剂的糠醛转化率高于80%的时间仅为5 h,而60Cu/ZnO催化剂的糠醛转化率高于80%的时间可以达到28 h,表明适当的SMSI作用有利于提升Cu/ZnO催化剂在糠醛加氢反应中的稳定性,而过强的SMSI作用会抑制其催化活性。

     

    Abstract: A series of Cu/ZnO catalysts were prepared by the coprecipitation method and the effect of Cu/Zn ratio on the strong metal support interaction (SMSI) as well as its relation to the catalytic performance of Cu/ZnO in the gaseous hydrogenation of furfural to furfuryl alcohol was investigated. The H2-TPR, XRD, SEM, TEM and XPS characterization results reveal that there exists the SMSI effect in the Cu/ZnO catalyst that influences the catalyst microstructure. ZnO support, acting as a geometric modifier on the active metal Cu particles, has a significant influence on the electronic state of the surface Cu species. The strength of SMSI is related to the Cu/Zn ratio and the SMSI strength of various Cu/ZnO catalysts follows the order of 20Cu/ZnO > 40Cu/ZnO > 60Cu/ZnO > 80Cu/ZnO. Under the same reaction conditions, the lifetime of the 20Cu/ZnO catalyst with a furfural conversion of above 80% is only 5 h, in comparison with the lifetime of 28 h for the 60Cu/ZnO catalyst. That is, appropriate SMSI can enhance the stability of the Cu/ZnO catalyst in the hydrogenation of furfural to furfuryl alcohol, whereas excessive SMSI is detrimental to the catalyst activity.

     

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