Study On Modified Cu/SiO₂ Catalyst For Methyl Acetate Hydrogenation To Ethanol

Because of the raising price and lacking of oil resources, fuel ethanol has a good application prospect as an alternative energy. More and more researchers pay attentions to the production of ethanol from acetic ester. Based on the Cu/SiO₂ catalyst, the catalytic performances of Cu/ZrO₂-SiO₂ with varied ZrO₂ contents and Cu-MnO/SiO₂ with varied MnO contents were investigated. The influence of calcination temperature?reduction temperature of new catalysts were studied too. Besides, the effect of reaction process conditions on the catalytic behavior and the stability performance of the catalysts were studied. The catalysts were characterized by N2 adsorption-desorption, X ray diffraction?XRD?, H2 temperature programmed reduction?H₂-TPR?, X-ray photoelectron spectroscopy. The main contents and results are as follows.?1? The influence of varied ZrO₂ contents to Cu/SiO₂?calcination temperature and reduction temperature were investigated. And the results showed that the catalyst exhibits the highest performance when the ratio of ZrO₂/SiO₂ is 1:5. The most suitable calcination temperature of catalysts is 450 ?, and the most suitable reduction temperature is 350?. And the study of stability of Cu/SiO₂ and Cu/ZrO₂-5SiO₂ reveals that the addition of ZrO₂ improved the stability of catalyst.?2? The influence of varied MnO contents to Cu/SiO₂ and the calcination of Cu-3MnO/SiO₂ were investigated. The results reveals the catalyst with MnO 3wt% exhibits the highest performance, and the best calcination temperature is 450?. The high performance was attributed to the bigger specific surface area ?the better dispersion of copper?the higher ratio of Cu⁺/?Cu⁺+Cu⁰?. The stability of Cu/SiO₂ and Cu-3MnO/SiO₂ were studied and the Me OAc conversion and ethanol selectivity were maintained at 95.7%?95.8%, and the loss of copper is less than Cu/SiO₂.?3? The influence of the reaction process condition were studied over the modified catalysts. The activity of catalysts went up with temperature when the temperature ranges from 210? to 340?, but there is little change in the activity when the temperature beyond 250?;the activity of catalysts went up with reaction pressure in 0-3 MPa; the activity of catalysts droped down with LHSV in 1-3 h-1; the activity of catalysts went up with H₂/Me OAc in 10-30, and the activity is low when H₂/Me OAc is below 15. In summary, the suitable reaction process condition is t=250??P=3MPa?LHSV=2 h-1?H2/Me OAc=15-30.