Production of monocyclic phenols by the liquid-phase hydrogenolysis of benzofuran and dibenzyl ether using in situ hydrogen production from methanol

We herein report our study into the hydrogenolysis of benzofuran, a model compound for the poorly decomposable compounds derived from lignin, over Pt supported catalysts in methanol in the absence of gaseous hydrogen. In this in situ hydrogenolysis reaction system, it was elucidated that both hydrogen production from methanol and selective hydrogenolysis of the furan moiety proceeded simultaneously to yield monophenolic compounds and gaseous hydrogen. This in situ hydrogenolysis reaction was investigated at temperatures between 180 and 220 degrees C and with reaction times ranging from 1 to 48 h. We found that the hydrogenolysis reaction was accelerated with increased hydrogen concentrations in the solvent. The molar ratio of consumed hydrogen to net hydrogen production increased gradually upon increasing the reaction temperature and time. In addition, the in situ hydrogenolysis of benzofuran under a hydrogen gas atmosphere revealed that the hydrogen produced in situ was more effective in the reaction than gaseous hydrogen, likely due to the dissolution and diffusion resistances of the solvent. Furthermore, dibenzyl ether was hydrogenolyzed to give monocyclic aromatic compounds under the same reaction conditions, suggesting that this in situ hydrogenolysis process could be effective in converting the by-products obtained during lignin depolymerization into valuable aromatic compounds.