Preparation of cyclohexanol from lignin-based phenolic concoction using controlled hydrogen delivery tool over in-situ Ru catalyst

Abstract

This work investigated hydrodeoxygenation-hydrogenation of lignin-based methoxyphenols (obtained through hydrothermal liquefaction (HTL) of lignin) to cyclohexanol in high yields over in situ generated Ru(0)@Mg(OH)2 catalyst in aqueous medium. The active catalyst Ru(0)@Mg(OH)2 is generated in situ from hydrous ruthenium oxide (HRO)/Mg(OH)2 under reaction conditions, as confirmed by various physiochemical techniques. Continuous and controlled addition of H2 at constant temperature facilitated in improving the selectivity of cyclohexanol compared to the conventional batch mode (pre-set pressure) process. Complete conversion of methoxyphenols with 93–99% selectivity for cyclohexanol was achieved at 10 mL/min H2 flow under comparatively milder reaction conditions. The adopted procedure and the in situ catalyst reported in this work is also effective for lignin-derived phenolic concoction.