Study On Catalyst For Hydrogenation Of Acetic Acid

The process for hydrogenation of acetic acid is significant in solving overcapacity of acetic acid industry and downstream products--ethanol and ethyl acetate production. The key of the process is to develop effective catalyst.According to our study, we find that the450℃reduced Cu-Zn/SiO2catalyst shows acetic acid conversion of100%, ethanol and ethyl acetate selectivity of19.83%and71.9%individually when reacted at325℃,1.9MPa, H2/acetic acid(mole)=20:1and LHSV=0.6h-\Cu-Zn/SiO2is an effective catalyst for hydrogenation of acetic acid for its high catalytic activity and destination products selectivity.Study of Cu-Zn based catalysts indicates that Fe is an effective promoter for Cu-Zn based catalysts, the addition of Fe improves their selectivity to ethyl acetate effectively. Cu-Zn-Fe/SiO2catalysts prepared by co-impregnation shows high acetic acid conversion and ethyl acetate selectivity and low by-products selectivity.Study of Cu-Zn-Fe/SiO2catalysts shows that ethyl acetate selectivity first increases and then decreases with increasing Fe content under325℃,1.9MPa, H2/acetic acid(mole)=20:1, LHSV=0.6h-1, the optimum Fe content is7wt%. Cu-Zn-7wt%Fe/SiO2catalyst shows highest ethyl acetate selectivity and lowest by-products selectivity. The study of effects of Cu. Zn. Al、 Fe indicates that Cu-Zn is effective component for hydrogenation of acetic acid, Fe improves ethyl acetate selectivity, while Al shows no promoting effect. The addition of Fe promotes catalytic stability as well. Study of reaction conditions of5.2wt%Cu-6.8wt%Zn-7wt%Fe/SiO2catalyst indicates325℃,1.9MPa, H2/acetic acid(mole)=20:1, and LHSV=0.6h-1to be optimum reaction conditions, when acetic acid conversion achieves100%, ethyl acetate and ethanol selectivity achieve79.7%and13.3%separately. When reacted at325℃,1.9MPa,5.2wt%Cu-6.8wt%Zn-7wt%Fe/SiO2shows maximum in ethanol and ethyl acetate productivity, to be1773.5g. kgcat-1. h-1and6893.6g. kgcat-1. h-1individually.XRD study of Cu-Zn based catalysts shows that all catalysts consist of Cu and Zn phases. The addition of Fe introduces Fe relating phases(Fe, Fe2O3and ZnFe2O4to catalysts and the diffraction peaks of Cu phase shift to higher angles with broadening as a result. The addition of Al doesn’t introduce Al relating phase, while the height and width of Cu diffraction peaks increased as a result.