Lignin is a natural organic polymer that is composed of phenolic residues. It comprises a large percentage of lignocellulosic biomass, so cost-effective valorization of lignin has received great attention to produce high-valued commodities. Among various chemicals that can be extracted from lignin, phenol is very useful as a fuel additive and a building block for resins and plastics. Products from pyrolysis of lignin, however, mainly include phenolic compounds with alkoxy groups, thus the reaction for selective removal of these groups through partial oxidation (POx) should be devised to obtain simple phenol.<br/>Here, we present a theory-guided development of the POx reaction of lignin. Titania-supported vanadia (VOx/TiO2) was employed as a catalyst which has also been utilized for POx of alcohols. Guaiacol was used as a model compound for the alkoxy-substituted phenolics, and reaction mechanisms for formation of phenol from guaiacol were elucidated by density functional theory (DFT) calculations. Through the mechanism study, kinetic feasibility of the phenol formation was examined, and the reaction kinetics catalyzed by VO3/TiO2 and V2O5/TiO2 were compared to identify catalytically active form of vanadia on titania. Experimental verification of the theoretical investigations will also be discussed; experiments were conducted using both lignin and the model compounds as the reactant, and the impact of the catalyst on the selectivity of phenol will be demonstrated.<br/><br/>

Theoretical and experimental developments of catalytic partial oxidation of lignin to simple phenols

2019 Fall National Meeting

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