The influence of different precipitants on the copper-based catalysts for hydrogenation of ethyl acetate to ethanol

Ethanol fuel has become a hot topic in the economic, political, environmental, and scientific areas. In this work, a new way for the synthesis of ethanol by hydrogenolysis of ethyl acetate is introduced and the impact of different precipitants on the ethyl acetate hydrogenolysis catalysts is systematically investigated by several considerations, including dispersion effects, the texture of the catalysts, and the copper phases in the surface layer of the reduced catalysts, etc. These precursors and catalysts are characterized by inductively coupled plasma-atomic emission spectroscopy, N2-adsoption, X-ray diffraction, transmission electronic microscope, H2 temperature-programmed reduction and X-ray photoelectron spectroscopy. It is confirmed that the choice of precipitant is of great importance. The samples are classified into two types, depending on the anion of precipitant. Except the catalyst prepared by (NH4)2CO3, in which low copper loading is observed, type B catalysts (–CO32−) possess smaller copper particles and larger BET surface than that of type A catalysts (–OH), while the difference of catalysts in the same type is not obvious. Moreover, the coexistence of Cu+ and Cu0 is only detected in reduced type B catalysts. In general, ethyl acetate hydrogenolysis activity varies considerably with the precipitant, in the following order: Na2CO3 ≥ NaHCO3 > NaOH ≥ KOH > (NH4)2CO3.