Synergetic Mechanism and Enhanced Catalytic Performance of Dimethyl Oxalate Hydrogenation to Ethanol Over Ag–Co Bifunctional Catalyst

In this work, a series of Ag_x–Co/SiO₂ catalysts for the hydrogenation of dimethyl oxalate (DMO) to ethanol (EtOH) or ethylene glycol (EG) were obtained by introducing Ag species into cobalt phyllosilicate (CoPS) layers. The synergetic mechanisms of Ag and Co species have been investigated in depth by a series of characterisation methods. The enhanced interaction between Ag and Co species facilitated the activation of Ag and Co species and the diffusion of hydrogen stored in Co to the Ag surface. This promotes the adsorption and dissociation of the H₂ and C=O bond and could facilitate the dissociation of the C–OH bond of EG. Thus, the hydrogenation of DMO to EtOH could be performed at a mild temperature over this novel Ag-Co bifunctional catalyst. Furthermore, the optimised Ag_0.18–Co/SiO₂ catalyst could switch the product selectivity from EG to EtOH as the reaction temperature increased, such as the selectivity of EG or EtOH would approach about 90% at 200 °C and 240 °C, respectively, as the weight hourly space velocity was 0.45 h⁻¹. This work would help to design efficient and stable ester hydrogenation catalysts.

Graphical Abstract