Efficient Conversion of Biomass-Derived Levulinic Acid to γ-Valerolactone over Polyoxometalate@Zr-Based Metal-Organic Frameworks: The Synergistic Effect of Brosnsted and Lewis Acidic Sites
Efficient Conversion of Biomass-Derived Levulinic Acid to γ-Valerolactone over Polyoxometalate@Zr-Based Metal-Organic Frameworks: The Synergistic Effect of Brosnsted and Lewis Acidic Sites
复制标题
在多金属氧酸盐@Zr基金属有机框架上将生物质衍生的乙酰丙酸高效转化为γ-戊内酯：布朗斯台德和路易斯酸性位点的协同效应
DOI：
10.1021/acs.inorgchem.1c00185
复制
发表时间：
2021-03-23
影响因子：
4.6
通讯作者：
Hu, Changwen
中科院分区：
文献类型：
--
作者：
Li, Jie;Zhao, Shuaiheng;Hu, Changwen
乙酰丙酸（LA）催化转化为γ-戊内酯（γ-GVL）是生物质降解的重要途径。由于级联反应中需要同时存在Bronsted和刘易斯两种酸性中心，本文采用浸渍法制备了一系列H3 PW_（12）O_（40）@ Zr基金属有机骨架（HPW@MOF808）。合成的HPW@M0F-808对于使用异丙醇作为氢供体将LA转化为γ-GVL具有活性。有趣的是，随着HPW负载量的增加，γ-GVL的产率先增加后降低，并且14%-HPW@MOF-808给出最高的γ-GVL产率（86%）。这是由于MOF-808中Zr 49的刘易斯酸性位和HPW的Bronsted酸性位之间的协同作用。根据实验结果，提出了一个合理的反应机理：Zr 4+中心催化羰基的转移氢化，HPW簇合物促进LA与异丙醇的酯化反应和内酯化反应生成γ-GVL。此外，HPW@MOF-808具有抗浸出性，可以重复使用五次而不会显著损失其催化活性。
Catalytic transformation of levulinic acid (LA) to gamma valerolactone (gamma-GVL) is an important route for biomass upgradation. Because both BrOnsted and Lewis acidic sites are required in the cascade reaction, herein we fabricate a series of H3PW12O40@Zr-based metal-organic framework (HPW@MOF808) by a facile impregnation method. The synthesized HPW@ MOF-808 is active for the conversion of LA to gamma-GVL using isopropanol as a hydrogen donor. Interestingly, with the increase in the HPW loading amount, the yield of gamma-GVL increases first and then decreases, and 14%-HPW@MOF-808 gave the highest gamma GVL yield (86%). The excellent catalytic performance was ascribed to the synergistic effect between the accessible Lewis acidic Zr49 sites in MOF-808 and Bronsted acidic HPW sites. Based on the experimental results, a plausible reaction mechanism was proposed: the Zr4+ sites catalyze the transfer hydrogenation of carbonyl groups and the HPW clusters promote the esterification of LA with isopropanol and lactonization to afford gamma-GVL. Moreover, HPW@MOF-808 is resistant to leaching and can be reused for five cycles without significant loss of its catalytic activity.