Enhanced selective hydrogenation of glycolaldehyde to ethylene glycol over Cu0-Cu+ sites

Selective hydrogenation of hydroxyaldehydes to polyalcohols is challenging due to the competitive hydrogenation of C=O and C-O. This study develops heterogeneous Cu catalysts for the selective synthe-sis of ethylene glycol via batch liquid-phase hydrogenation of glycolaldehyde. SiO2 supported Cu, fabri-cated by ammonia evaporation, enables to catalyze the C=O bond hydrogenation with retaining the C-O bond intact, yielding higher selective hydrogenation activity with ethylene glycol selectivity up to 99.8 % relative to MgO, Al2O3, CeO2, and TiO2 supports and Cu/SiO2 synthesized by deposition-precipitation and impregnation. Characterizations confirm that highly efficient 20Cu/SiO2-AE-623 K catalyst fabricated by ammonia evaporation is featured with larger Cu0 and Cu+ surface areas, of which the Cu+ species created from reducing copper phyllosilicate exhibit higher reactivity. A synergistic effect between Cu+ and Cu0 facilitates the selective adsorption/activation of glycolaldehyde on Cu+ sites and the dissociation of H2 on Cu0 sites, bringing a remarkable improvement in the selective hydrogenation performance.(c) 2022 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

Automated summary

This study develops heterogeneous Cu catalysts for the selective synthesis of ethylene glycol via batch liquid-phase hydrogenation of glycolaldehyde. SiO2 supported Cu, fabricated by ammonia evaporation, enables to catalyze the C=O bond hydrogenation with retaining the C-O bond intact, yielding higher selective hydrogenation activity with ethylene glycol selectivity up to 99.8%. A synergistic effect between Cu+ and Cu0 facilitates the selective adsorption/activation of glycolaldehyde on Cu+ sites and the dissociation of H2 on Cu0 sites, bringing a remarkable improvement in the selective hydrogenation performance.