Probing the promotional roles of cerium in the structure and performance of Cu/SiO2 catalysts for ethanol production

In this contribution, the efficient hydrogenation of dimethyl oxalate (DMO) to ethanol was achieved over a series of cerium promoted Cu/SiO2 (xCe-Cu/SiO2) catalysts prepared by a urea-assisted gelation approach. As a promoter, Ce played a crucial role in improving the structure, properties and catalytic performance of the Cu/SiO2 catalysts. The structure and chemical properties of the synthesized catalysts were characterized by XRD, FT-IR, in situ XRD, TEM, STEM-EDX mapping, N2O titration, H-2-TPR, H-2-TPD, XPS, XAES, etc. The characterization results disclosed that the addition of a Ce promoter to the Cu/SiO2 catalysts remarkably increased the Cu dispersion and retarded the sintering of small-sized Cu species. The strong interaction between the Ce promoter and Cu species substantially changed the redox properties of xCe-Cu/SiO2 catalysts and made the Cu2+ species easy to reduce. In addition, the activation ability of H-2 species was significantly improved in the xCe-Cu/SiO2 catalysts, as evidenced by H-2-TPD studies. Among these synthesized catalysts, the 1Ce-Cu/SiO2 catalyst with a 1.0 wt% Ce loading exhibited the highest catalytic activity (100% DMO conversion), ethanol selectivity (91.8%) and stability. This enhancement of catalytic activity, ethanol selectivity and stability is very promising for the development of an alternative route for the production of ethanol by hydrogenation of DMO from syngas.