Revelation of bimolecular tautomerization induced by the concerted and radical interactions in lignin pyrolysis

作     者：Wen-luan Xie Bin Hu Wen-ming Zhang He-long Li Guo-yong Song Ji Liu Qiang Lu Wen-luan Xie;Bin Hu;Wen-ming Zhang;He-long Li;Guo-yong Song;Ji Liu;Qiang Lu

作者机构：National Engineering Research Center of New Energy Power GenerationNorth China Electric Power UniversityBeijing 102206China Beijing Key Laboratory of Lignocellulosic ChemistryBeijing Forestry UniversityBeijing 100083China Suzhou Institute of North China Electric Power UniversitySuzhou 215123JiangsuChina 

出 版 物：《能源化学:英文版》 (Journal of Energy Chemistry)

年 卷 期：2023年第84卷第9期

页      面：1-10页

核心收录：

学科分类：080703[工学-动力机械及工程] 08[工学] 0807[工学-动力工程及工程热物理] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0822[工学-轻工技术与工程] 

基　　金：the National Natural Science Foundation of China(52276189,52106241) Natural Science Foundation of Jiangsu Province(BK20221248)for financial support。 

主　　题：Lignin pyrolysis Interaction mechanism Tautomerism Hydroxyl-assisted hydrogen transfer Radical chain reaction 

摘      要：Bimolecular interactions play crucial roles in lignin pyrolysis.The tautomerization of key intermediates has a significant impact on the formation of stable products,whereas bimolecular tautomerization has been rarely clarified.In the present work,the bimolecular tautomerization mechanism induced by both concerted and radical interactions was proposed and carefully confirmed.A characteristicβ-O-4 lignin dimer,2-phenoxy-1-phenylethanol(α-OH-PPE),was used as the model compound to reveal two representative keto-phenol and enol-keto tautomerism mechanisms,based on theoretical calculations combined with pyrolysis experiments.The results indicate that the unimolecular tautomerism as the rate-determining step limits product generation,due to fairly high energy barriers.While the free hydroxy compounds and radicals derived from initial pyrolysis can further initiate bimolecular tautomerism reactions through the one-step concerted hydroxyl-assisted hydrogen transfer(hydroxylAHT)and two-step radical hydrogen abstraction interactions,respectively.By alleviating and even avoiding the large ring tension of tautomerism,the unstable tautomers(2,4-cyclohexadienone and1-hydroxy styrene)can be rapidly tautomerized into stable phenol and acetophenone with the help of intermolecular interaction.Benefitting from the significant advantage of retro-ene fragmentation in breaking theβ-O-4 bond to form tautomers,a large amount of stable phenolic and ketone products can be generated following bimolecular tautomerization in the pyrolysis ofβ-O-4 linked lignin.