Lewis酸性MOF催化葡萄糖异构和差向异构反应机制  

Catalytic mechanism of glucose isomerization and epimerization over Lewis acidic MOF catalysts

作　　者：刘苗 何颖[2] 焦莹莹 应制洲 杨洋 孙亮亮 张元宝 罗群兴 Liu Miao;He Ying;Jiao Yingying;Ying Zhizhou;Yang Yang;Sun Liangliang;Zhang Yuanbao;Luo Qunxing(School of Chemical Engineering,Northwest University,Xi’an 710069,Shaanxi,China;Key Laboratory of Syngas Conversion of Shaanxi Province,School of Chemistry and Chemical Engineering,Shaanxi Normal University,Xi’an 710119,Shaanxi,China;College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,Fujian,China)

机构地区：[1]西北大学化工学院,陕西西安710069 [2]陕西省合成气转化重点实验室,陕西师范大学化学化工学院,陕西西安710119 [3]厦门大学化学化工学院,福建厦门361005

出　　处：《工业催化》2023年第10期29-34,共6页Industrial Catalysis

基　　金：国家自然科学基金资助项目(21706155);陕西省自然科学基础研究计划项目(2020JQ-572);西北大学青年学术英才支持计划和大学生创新创业训练计划项目(S202010697312,202210697150)。

摘　　要：葡萄糖异构和差向异构是生物质转化和稀有单糖催化合成的重要反应路径之一。研究表明,Lewis酸性Cr-MIL-101和Zr-UiO-66骨架金属位点呈现不同反应效能,但催化反应机制尚不明确。以Cr-MIL-101和Zr-UiO-66中的Cr(Ⅲ)和Zr(Ⅳ)团簇作为模型单元,采用自旋极化密度泛函理论研究两种催化剂本征活性位上葡萄糖异构和差向异构反应过渡态及能垒,阐明不同金属中心影响异构和差向异构反应路径的本质原因,结果表明,两种催化体系存在相似的基元反应步骤,都经历了负氢离子和反负氢离子转移两个过程,但由于催化中心配位活化机制不同,导致Lewis酸性Cr(Ⅲ)中心上负氢离子转移活化能低于反负氢离子转移活化能,Lewis酸性Zr(Ⅳ)中心上负氢离子转移活化能高于反负氢离子转移活化能。Glucose isomerization and epimerization are important catalytic reactions for biomass conversion and synthesis of rare sugars.The previous results have shown that Lewis acidic Cr-MIL-101 and Zr-UiO-66 catalysts deliver different catalytic function in glucose isomerization and epimerization,yet the mechanism and reason are unclear.Herein,Cr(Ⅲ)clusters and Zr(Ⅳ)clusters are employed as model units,and spin-polarized density functional theory are used to explore the transition states and energy barriers in the process of glucose isomerization and epimerization.The resultant effect mechanism of glucose transformation over different metal sites is elucidated.It is found that the elementary reaction steps involved over Cr-MIL-101 and Zr-UiO-66 are similar and undergo the hydride transfer and anti-hydride transfer also.However,because of different coordination activation mode between glucose and metal active centers,the activation energy of hydride transfer over Lewis acidic Cr(Ⅲ)clusters is lower than that of anti-hydride transfer,whereas it is contrary in the case of Lewis acidic Zr(Ⅳ)clusters.

关 键 词：催化化学 葡萄糖 异构 差向异构 金属有机骨架 密度泛函理论 

分 类 号：TQ013.2[化学工程] O643.3[理学—物理化学]