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 

机构地区：[1]National Engineering Research Center of New Energy Power Generation,North China Electric Power University,Beijing 102206,China [2]Beijing Key Laboratory of Lignocellulosic Chemistry,Beijing Forestry University,Beijing 100083,China [3]Suzhou Institute of North China Electric Power University,Suzhou 215123,Jiangsu,China

出　　处：《Journal of Energy Chemistry》2023年第9期1-10,共10页能源化学（英文版）

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

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.

关 键 词：Lignin pyrolysis Interaction mechanism TAUTOMERISM Hydroxyl-assisted hydrogen transfer Radical chain reaction 

分 类 号：TK6[动力工程及工程热物理—生物能]