Cobalt-silver catalyst with low metal content for highly efficient synthesis of methyl glycolate through synergistic effect

Abstract

The Co-Agx/TiO2 catalysts with low mass content of Co and Ag were synthesized through the impregnation method and investigated for dimethyl oxalate (DMO) hydrogenation to methyl glycolate (MG). Remarkably, the Co-Ag0.7/TiO2 catalyst with an Ag concentration of 0.7 wt%, exhibited an impressive yield of MG of ∼94.4 %, surpassing the yields of MG obtained with Co/TiO2 (∼54 %) and Ag0.7/TiO2 (∼69 %) catalysts. Various characterizations elucidated that the exceptional catalytic performance of Co-Ag0.7/TiO2 can be ascribed to the synergy between Co and Ag, resulting in the formation of AgCoO2 as high active site can improve the adsorption and activation of DMO and H2 on catalyst surface. Additionally, the doping of a small amount of Ag regulated the contents of Lewis acidic and Brønsted acidic sites, leading to a high conversion of DMO and selectivity of MG. Furthermore, the excellent MG yield and long-term stability (at least 200 h) facilely obtained over our catalyst under mild reaction conditions guarantee a feasible prospect in the industrial application. This study not only unraveled the superior performance of the Co-Ag synergistic catalyst, but also carried significant implications for developing catalysts with low-content in DMO hydrogenation to MG.