Low-Temperature Hydrogenation of Methyl Acetate to Ethanol over a Manganese-Modified Cu/SiO₂ Catalyst

Abstract

One of the crucial steps in producing ethanol from syngas is the hydrogenation of methyl acetate (MA). There has been an increase in the use of reducible metal oxides as supports or additives in copper-based catalysts, which shows good performance in MA hydrogenation. However, a high temperature of 220–250 °C is generally required for MA hydrogenation, and the role of metal ion-oxygen vacancy (Mn+-Ov) defect structure in the catalyst is still controversial. Here, a series of manganese-modified Cu/SiO2 catalysts are prepared by the ammonia evaporation method followed by the ion-exchange process. At reaction temperatures as low as 180 °C, the optimal catalyst with a Cu/Mn ratio of 1.6 shows excellent activity and stability. Combined with various characterizations, MA-temperature-programmed desorption (TPD), and in situ MA adsorption Fourier transform infrared (FT-IR) spectroscopy experiments, it is evidenced that the surface Mn2+-Ov defect acts as one of the main active sites during the reaction, which can promote the adsorption and activation of CO/C–O bonds in the MA molecules. The insights into the role of manganese species could give guidance to the further design of high-performance catalysts for the hydrogenation of the CO/C–O bond.

Surface Amine Species Promoted Cu/SiO2 Catalysts for the Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

“…The peaks centered at 570.0 and 573.3 eV are assigned to Cu 0 and Cu + , respectively. 26 By assuming the Cu 0 and Cu + species have identical atomic sensitivity factors and occupy the same areas, the molar proportion of surface Cu 0 (X Cu 0 ) and Cu + specific surface area (S Cu + ) are calculated, 42 which are listed in Table S2. The X Cu 0 is increased with enlarging the nitrogen content and attains the maximum value of 80.0% at Cu/SiO 2 -1.7NH, which is in accordance with a shift to lower binding energy of the XPS spectra.…”