Studies Of The Pyrolysis Behaviors Of Lignin Model Compounds

Biomass is an important renewable energy, so its important part lignin, whose content is after cellulose has attracted much attention especially in thermo-chemical conversion and utilization. As both the structure and reaction property of real lignin is rather complex, most of the study of lignin will use lignin model compounds instead. In this paper, in order to explore the pyrolysis property of lignin, model compounds were selected to study the pyrolysis behavior of lignin mold compounds from the shallower to the deeper. The main contents in this paper are as follows.The products distribution of three guaiacyl type model compounds(vanillin, vanillic acid and vanillin alcohol) and one kind of dimer model compound(benzyl phenol) were attained by using Py-GC/MS method; then this data was used to design the pyrolysis reaction paths; following that, activation energies of the reaction paths were calculated; finally, found out the feasible paths and pyrolysis behaviors of lignin model compounds by analyzing activation energies and other factors.There were almost no products of vanillin detected at low temperature, which meant thermal stability of vanillin was higher than vanillic acid and vanillic alcohol. After analyzing the computational results, the generation of guaiacol which was their common product, was found tend to through synergy, and the trend of specific pyrolysis and common pyrolysis of these three model compounds were different.The dissociation energy of Cα-O bond was the lowest, which caused Cα-O bond the easiest one to reaction, also brought the high yield of benzyl. As hydroquinone generated was an exothermic reaction, and benzoquinone was endothermic, the yield of former was higher. High activation energy caused the low yield of other products.After computing phenol glycerol-α-phenyl ether, another α-O-4 dimer, the first pyrolysis one was likely to be the Cα-O bond and Cα-Cβ bond, and the main products were small molecular substances and phenolic compounds, which were different from the products of a β-O-4 one in the category, structure and priority.