Selective Demethoxylation of Guaiacols to Phenols using Supported MoO<sub>3</sub> Catalysts
Huaizhou Yang, Wang Yin, Xiaotian Zhu, Peter J. Deuss, Hero J. Heeres
Abstract
Abstract Lignin‐derived monomers with methoxy substituents are abundantly present in bioliquids derived from lignocellulosic biomass. Examples are the products obtained from the reductive catalytic fractionation of lignin (RCF) and pyrolysis of lignocellulosic biomass and hydrotreated products thereof. An attractive valorization step for these liquids involves demethoxylation to obtain alkylated phenols through selective catalytic hydrodeoxygenation (HDO). Within the context of sustainable chemistry, there is a strong drive to use cheap, non‐precious metal catalysts for this purpose. In this study, the HDO of guaiacol (5 wt% in toluene) was investigated in a continuous fixed‐bed reactor at 380 °C, 20 bar over supported MoO 3 catalysts. MoO 3 (5 %) supported on TiO 2 (P25) was shown to give superior performance compared with MoO 3 supported on anatase TiO 2 , Al 2 O 3 , SiO 2 , Nb 2 O 5 , CeO 2, and ZrO 2 . Additional studies involving variation of the Mo loading and process conditions were performed, and the highest selectivity to demethoxylated phenolics like phenol and methylated phenols was 82 % at 97 % conversion of guaiacol. Both 4‐ n ‐propylguaiacol and a realistic guaiacols‐rich feed isolated from a representative pyrolysis oil were also successfully demethoxylated with the 5 % MoO 3 /TiO 2 catalyst.