Silver modified Cu/SiO₂ catalyst for the hydrogenation of methyl acetate to ethanol

A series of silver modified Cu/SiO₂ catalysts were synthesized with ammonia-evaporation method and applied in vapor-phase hydrogenation of methyl acetate to ethanol. The influence of additive ‘Ag’ on the structural evolution of catalyst was systematically studied by several characterization techniques, such as N₂ adsorption–desorption, N₂O titration, PXRD, FTIR, in-situFTIR, H₂-TPR, H₂-TPD, XPS and TEM. Results showed that incorporation of a small amount of Ag could enhance the structural stability, and the strong interaction between Cu and Ag species was conducive to increase the dispersion of copper species and create a suitable Cu⁺/(Cu⁰ + Cu⁺) ratio, which was proposed to be responsible for the improved catalytic activity. The maximum conversion of MA (94.1%) and selectivity of ethanol (91.3%) over optimized Cu-0.5Ag/SiO₂ and 120 h on stream without deactivation under optimal conditions demonstrates its excellent stability.