Highly active Ce, Y, La-modified Cu/SiO₂ catalysts for hydrogenation of methyl acetate to ethanol

Rare earth element (Ce, Y, and La) modified Cu/SiO₂ catalysts via hydrolysis precipitation and impregnation method were fabricated for the vapor-phase hydrogenation of methyl acetate to ethanol. LaO_x showed the most pronounced promotion in the catalytic tests. After detailed characterizations, via N₂ adsorption-desorption, XRD, N₂O chemisorption, FTIR, H₂-TPR, H₂-TPD, TEM, XPS, and TG/DTA, we found that the addition of promoter LaO_x can decrease the particle size while in turn, it can increase the dispersion of copper species. The strong interactions between copper and lanthanum atoms alter the surface chemical states of the copper species. This results in the generation of more Cu⁺ species and high S_Cu⁺ values, which are responsible for the excellent activity and stability during hydrogenation. In addition, the content of additive LaO_x and reaction conditions (reaction temperature and LHSV) were optimized. Then, the long-term stability performance was evaluated over the selected catalyst in contrast with Cu/SiO2.