Direct Catalytic Hydrogenolysis of Kraft Lignin to Phenols in Choline-Derived Ionic Liquids
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- 作者：Fei Liu ; Qiaoyun Liu ; Aiqin Wang ; Tao Zhang
- 刊名：ACS Sustainable Chemistry & Engineering
- 出版年：2016
- 出版时间：July 5, 2016
- 年：2016
- 卷：4
- 期：7
- 页码：3850-3856
- 全文大小：443K
- 年卷期：0
- ISSN：2168-0485
文摘
A new dual catalyst system composed of choline-derived ionic liquids (ILs) and Pd/C was developed for the selective hydrogenolysis of Kraft lignin to monophenols. Among a series of investigated choline-derived ILs, [Ch][MeSO3] displayed a strong acidity, good thermal stability, and excellent lignin solubility. Under the reaction conditions of the mass ratio of [Ch][MeSO3] to Pd/C being 1, the Pd/C loading of 3.5 wt %, H2 pressure of 2.0 MPa, reaction time of 5 h, and temperature of 200 °C, the conversion of Kraft lignin and the selectivity to phenol (PL) and catechol (COL) reached 20.3%, 18.4%, and 18.1%, respectively. In order to rationalize the formation of PL and COL in our [Ch][MeSO3]-Pd/C system, the hydrogenolysis of a suitable lignin model compound (guaiacylglycerol-β-guaiacyl ether) was studied under the same condition for Kraft lignin. The results suggested that the mechanism involved fragmentation of lignin catalyzed by both acid and Pd/C, followed by acid-catalyzed C–O and C–C cleavage of the fragmented compounds resulting in the formation of PL and COL.