Elevating dimethyl oxalate hydrogenation activity over core–shell Cu/SiO2@CeO2 catalysts

•The 30Cu/SiO2@5CeO2 catalyst sample exhibited the best ethylene glycol (EG) yield of up to 95.9 % under low H2/DMO=30.•Superior performance could be maintained up to 200 h without obvious deactivation.•Adding CeO2 boosts the EG yield from 24.4% to 95.9%•CeO2 on catalyst surfaces aids Cu+ formation via interaction with adjacent Cu nanoparticles.•Electron interactions between Cu and Ce promote Cu+ formation and facilitate C=O adsorption and activation. Increasing dimethyl oxalate (DMO) hydrogenation activity remains a challenge. A Cu catalyst was designed by creating Cu nanoparticles (NPs) over SiO2 layer formed on the CeO2 particles (SiO2@CeO2) using the ammonia evaporation method followed by the calcination and reduction step. The optimized 30Cu/SiO2@5CeO2 catalyst shows good performance in the micro-packed bed reactor (100 % DMO conversion, 95.9 % ethylene glycol (EG) selectivity, 200 h stability) under the condition of the ratio of H2 to DMO (H2/DMO) = 30, 190 °C and 2 MPa in the run, and CeO2 was proved to be effective in the DMO hydrogenation process. The exposed CeO2 on the surface of catalyst was found to facilitate the formation of Cu+ by its interaction between adjacent Cu nanoparticles, resulting in the faster adsorption and dissociation of C=O bond on the catalyst surface, according to the characterization results obtained by the XRD, XPS and in situ FT-IR, etc.