高等学校化学学报 ›› 2022, Vol. 43 ›› Issue (6): 20220138.doi: 10.7503/cjcu20220138

• 分析化学 • 上一篇    下一篇

Sn-Al-β分子筛酸性在葡萄糖转化反应中作用的固体NMR研究

李志光1,2, 齐国栋1, 徐君1(), 邓风1   

  1. 1.中国科学院精密测量科学与技术创新研究院, 武汉物理与数学研究所, 波谱与原子分子物理国家重点实验室, 武汉磁共振中心, 武汉 430071
    2.中国科学院大学, 北京 100049
  • 收稿日期:2022-03-03 出版日期:2022-06-10 发布日期:2022-04-17
  • 通讯作者: 徐君 E-mail:xujun@wipm.ac.cn
  • 基金资助:
    国家自然科学基金(21872170);湖北省自然科学基金(2021CFA021)

Role of Catalyst Acidity in Glucose Conversion over Sn-Al-β Zeolite as Studied by Solid-state NMR

LI Zhiguang1,2, QI Guodong1, XU Jun1(), DENG Feng1   

  1. 1.National Center for Magnetic Resonance in Wuhan,State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics,Wuhan Institute of Physics and Mathematics,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan 430071,China
    2.University of Chinese Academy of Sciences,Beijing 100049,China
  • Received:2022-03-03 Online:2022-06-10 Published:2022-04-17
  • Contact: XU Jun E-mail:xujun@wipm.ac.cn
  • Supported by:
    the National Natural Science Foundation of China(21872170);the Natural Science Foundation of Hubei Province, China(2021CFA021)

摘要:

制备了一系列具有不同酸性质的β分子筛催化剂, 通过固体核磁共振(NMR)探针分子技术对其酸性质进行了表征, 并考察了其催化葡萄糖转化为乙酰丙酸甲酯的性能. 吸附三甲基磷的31P NMR实验结果表明, 含有骨架Sn以及Al原子的Sn-Al-β催化剂同时具有Br?nsted与Lewis酸性. 通过2-13C-丙酮探针分子区分出 3种酸强度的Br?nsted酸位, 其中一种酸强度接近“超强酸”, 可能是由于空间邻近的Br?nsted酸位和Lewis酸位发生协同作用产生的. 葡萄糖转化为乙酰丙酸甲酯的催化反应结果表明, 相比于分别只含有Lewis酸位和Br?nsted酸位的Sn-β和Al-β样品以及两者的物理混合样品, Sn-Al-β分子筛催化剂具有高催化活性与产物选择性, 这主要是由于Br?nsted酸位和Lewis酸位的协同作用产生了强Br?nsted酸位, 这种强Br?nsted酸位进一步导致了更高的催化活性.

关键词: 分子筛, 探针分子, 酸性, 固体核磁共振, 葡萄糖转化

Abstract:

A series of β zeolite catalysts with different acidic properties were prepared. The acidity of these catalysts was characterized by solid-state nuclear magnetic resonance(NMR) probe molecule technique. These catalysts were tested for the conversion of glucose to methyl levulinate. 31P NMR of trimethyl phosphine adsorbed on Sn-Al-β zeolite showed that the introduction of framework Sn and Al atoms resulted in both Br?nsted and Lewis acidity. Three Br?nsted acid sites with different acidic strength were distinguished by 13C NMR of 2-13C-acetone probe molecule, with one being close to “super acid”, which is most likely generated by the synergistic effect between the spatially adjacent Br?nsted and Lewis acid sites. The catalytic reaction of glucose to methyl levulinate showed that Sn-Al-β was superior in catalytic activity and selectivity to methyl levulinate as compared to Sn-β containing only Lewis acid sites, Al-β containing only Br?nsted acid sites and the mixed sample of Sn-β and Al-β. This can be accounted by the synergy of Br?nsted and Lewis acid sites and stronger Br?nsted acidity of Sn-Al-β.

Key words: Zeolite, Probe molecule, Acidity, Solid-state nuclear magnetic resonance(NMR), Glucose conversion

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