Du Boyu, Chen Changzhou, Sun Yang, Yang Ming, Yu Mengtian, Liu Bingyang, Wang Xing, Zhou Jinghui
Liaoning Key Laboratory of Pulp and Papermaking Engineering, Dalian Polytechnic University Dalian Liaoning 116034 China
Light Industry and Food Engineering College, Guangxi University Nanning Guangxi 530004 China.
RSC Adv. 2020 Aug 26;10(52):31479-31494. doi: 10.1039/d0ra05069e. eCollection 2020 Aug 21.
In this study, effects of catalyst types, reaction temperatures, reaction times, reaction solvents and ultrasound frequencies were carefully investigated to improve the yields and characteristics of various depolymerization products of organosolv lignin. Generally, both catalyst types and ultrasound frequencies played important roles in promoting lignin depolymerization and reducing char yield. In particular, the yield and distribution of phenolic monomer (PM) products were greatly influenced by pore structure and acidity of the catalyst. The optimal reaction condition was got in isopropanol at 310 °C for 6 h with 30% ultrasound frequency and 50% phosphotungstic acid (PTA)/MCM-41 catalyst. The highest yields of PM, bio-oil, liquid fuels and lignin conversion were reached as 8.63 wt%, 86.89 wt%, 95.52 wt% and 98.54 wt%, respectively. The results showed that ultrasound acoustic cavitation could enhance the depolymerization of lignin, thus greatly enhancing production of liquid fuels. Simultaneously, the hydrogen composition and high heating value of various lignin depolymerization products improved, and the oxygen content decreased, indicating that hydrogenation and/or hydrodeoxygenation happened during the depolymerization process. Finally, we also found that the 50% PTA/MCM-41 catalyst had high stability; it could be reused for up to five cycles without loss of catalytic activity.
在本研究中，仔细考察了催化剂类型、反应温度、反应时间、反应溶剂和超声频率对提高有机溶剂法木质素各种解聚产物的产率和特性的影响。一般来说，催化剂类型和超声频率在促进木质素解聚和降低焦炭产率方面都起着重要作用。特别是，酚类单体（PM）产物的产率和分布受催化剂的孔结构和酸度的显著影响。最佳反应条件是在异丙醇中，于310℃反应6小时，超声频率为30%，使用50%的磷钨酸（PTA）/MCM-41催化剂。PM、生物油、液体燃料的最高产率和木质素转化率分别达到8.63 wt%、86.89 wt%、95.52 wt%和98.54 wt%。结果表明，超声空化作用可增强木质素的解聚，从而大大提高液体燃料的产量。同时，各种木质素解聚产物的氢含量和高热值提高，氧含量降低，表明在解聚过程中发生了氢化和/或加氢脱氧反应。最后，我们还发现50%的PTA/MCM-41催化剂具有高稳定性；它可以重复使用多达五个循环而不损失催化活性。
