北京林业大学学报2017，Vol.39Issue(5)：117-124,8.DOI:10.13332/j.1000-1522.20160399
离子液体[BMIM]Cl与H5PV2Mo10O40双效催化降解麦草碱木质素的研究
Experimental evaluation on the ionic liquid [ BMIM ] Cl and H5PV2Mo10O40 dual function catalytic degradating wheat straw alkali lignin
摘要
Abstract
The H5PV2Mo10O40 heteropoly acid was prepared by the conventional methods and was characterized with FT-IR, XRD and SEM. In{H5PV2Mo10O40+ [ BMIM ] Cl} dual function catalytic system and [ BMIM] Cl single function catalytic system, the effects of reaction time, reaction temperature and the amount of H5PV2Mo10O40 on the lignin degradation process were studied, and the degradation mechanism was also discussed preliminarily. The results indicated that the contents of P, V, Mo in the synthesis H5PV2Mo10O40 heteropoly acid accorded with the relationship of 1: 2: 10, and the H5PV2Mo10O40 heteropoly acid had the typical Keggin structure. Under the optimal reaction condition, i. e. , 140℃, 3 hours, the ionic liquids were used as the catalysts, the contents of total hydroxyl of alkali lignin increased from 3. 49 to 10. 92 mol/kg after reaction, and the mass fraction of vanillin and syringaldehyde were 2. 00% and 2. 15% in liquid products, respectively. When 20% H5PV2Mo10O40 was added, the optimal reaction time and temperature were 6 hour and 120 ℃, and the total hydroxyl increased from 3. 49 to 14. 12 mol/kg in solid degradation products. The molar mass reduced from 7. 691 to 1. 589 kg/mol. Only vanillin was found in liquid products, and its mass fraction was 6. 97%. It was believed that H+ attacked oxygen atom on the β-O-4 bond in lignin firstly when [ BMIM] Cl catalyzed lignin alone. At the same time, the positive charge was transferred to the β position, and then the oxygen atom in the water molecule attacked the β position which had positive charge. As a result, catalyst H+ was eliminated andβ-O-4 bond generated guaiacol due to the hydrolytic cleavage. Then the side chain generated vanillin and syringaldehyde by the oxidation reaction. When H5PV2Mo10O40 was added, [ PV2Mo10O40 ] 5- released VO2+ and its valencestate was changed from V ( V ) to V ( IV ) . The single electron oxidation model compounds were obtained and the lignin was demethylated. It was thought that the lignin demethoxy group was changed from lignin-type lignin to guaiacol-type lignin, not only without any clove aldehydes were found in the liquid product but also the contents of vanillin were increased.关键词
离子液体/杂多酸/双效催化降解/麦草碱木质素Key words
ionic liquid/heteropoly acid/dual function catalytic degradation/wheat straw alkali lignin分类
化学化工引用本文复制引用
刘晓乐,任世学,侯莲霞,李淑君..离子液体[BMIM]Cl与H5PV2Mo10O40双效催化降解麦草碱木质素的研究[J].北京林业大学学报,2017,39(5):117-124,8.基金项目
中央高校基本科研业务费专项(2572017EB07)、黑龙江省自然科学基金项目(C2015056). （2572017EB07）
