Efficient one-pot hydrogenolysis of biomass-derived xylitol into ethylene glycol and 1,2-propylene glycol over Cu–Ni–ZrO2 catalyst without solid bases

Abstract

The directly selective hydrogenolysis of xylitol to ethylene glycol (EG) and 1,2-propylene glycol (1,2-PDO) was performed on Cu–Ni–ZrO2 catalysts prepared by a co-precipitation method. Upon optimizing the reaction conditions (518 K, 4.0 MPa H2 and 3 h), 97.0% conversion of xylitol and 63.1% yield of glycols were obtained in water without extra inorganic base. The catalyst still remained stable activity after six cycles and above 80% total selectivity of glycols was obtained when using 20.0% xylitol concentration. XRD, TEM and ICP results indicated that Cu–Ni–ZrO2 catalysts possess favorable stability. Cu and Ni are beneficial to the cleavage of CO and CH bond, respectively. To reduce the hydrogen consumption, isopropanol was added as in-situ hydrogen source and 96.4% conversion of xylitol with 43.6% yield of glycols were realized.