Catalytic performance of La-modified Cu/SiO2 in the hydrogenation of methyl acetate

A series of Cu/SiO₂ catalysts modified with lanthanum (La) (30Cu-nLa/SiO₂, n=0, 0.5, 1 and 2) were synthesized using the ethanol (EtOH)-assisted ammonia-evaporation method; their catalytic performance in the gas-phase hydrogenation of methyl acetate (MeOAc) to produce ethanol (EtOH) was investigated. The results indicate that the catalytic performance of Cu/SiO₂ can be greatly enhanced by La modification. In particular, the 30Cu-0.5La/SiO₂ catalyst exhibits excellent performance in the MeOAc hydrogenation; under 230 °C, 2 MPa H₂, an LHSV of 2 h^-1 and an H₂/MeOAc molar ratio of 20, the MeOAc conversion reaches 98.5%, with a total EtOH yield of 97.0%. The N₂-sorption, XRD, ICP-OES, H₂-TPR, FT-IR, TEM, XPS, and AES characterization results reveal that the introduced La metal has a strong interaction with Cu, which can promote the dispersion of the copper species on the SiO₂ support. Moreover, the content of Cu⁺ is increased significantly, which can enhance the electronic interaction with MeOAc via the acyl and methoxide groups and thus promote the hydrogenation of MeOAc to EtOH.