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  

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

作　　者：李志光 齐国栋 徐君 邓风 LI Zhiguang;QI Guodong;XU Jun;DENG Feng(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;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[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

出　　处：《高等学校化学学报》2022年第6期72-80,共9页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:21872170,U1932218,21733013,22061130202);湖北省自然科学基金(批准号:2021CFA021,2020CFB552)资助。

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Brønsted与Lewis酸性.通过2-13C-丙酮探针分子区分出3种酸强度的Brønsted酸位,其中一种酸强度接近“超强酸”,可能是由于空间邻近的Brønsted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Brønsted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Brønsted酸位和Lewis酸位的协同作用产生了强Brønsted酸位,这种强Brønsted酸位进一步导致了更高的催化活性.A series ofβzeolite 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-βzeolite showed that the introduction of framework Sn and Al atoms resulted in both Brønsted and Lewis acidity.Three Brønsted 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 Brønsted and Lewis acid sites.The catalytic reaction of glucose to methyl levulinate showed that Sn-Al-βwas superior in catalytic activity and selectivity to methyl levulinate as compared to Sn-βcontaining only Lewis acid sites,Al-βcontaining only Brønsted acid sites and the mixed sample of Sn-βand Al-β.This can be accounted by the syner⁃gy of Brønsted and Lewis acid sites and stronger Brønsted acidity of Sn-Al-β.

关 键 词：分子筛 探针分子 酸性 固体核磁共振 葡萄糖转化 

分 类 号：O657[理学—分析化学]