Hydrogenation Of Ethyl Acetate To Ethanol Over Cu-Based Catalysts

Ethanol was widely used in chemical industry,pharmaceuticals,food manufacture and other fields. With the increasingly prominent conflict between energy shortages and environmental pollution, the fuel ethanol had become the world’s focus on renewable energy development. At present, the traditional method about production of ethanol was food fermentation in China,which not only has low economic benefits since strongly affected by food prices but also low production efficiency. However, the excess capacity of acetic acid and the gap between the price of ethanol and acetic acid had brought the new opportunity to the industry of coal chemical industry. In this thesis, ethanol production was realized by indirect hydrogenation of acetic acid. esterification of acetic acid firstly, and then followed by hydrogenation of the acetate. Using the acetic acid indirect hydrogenation method could not only avoid serious corrosion to equipment, but also developed a new type of copper-based catalyst for hydrogenation of ethyl acetate, instead of noble metal catalyst for direct hydrogenation of acetic acid, to save a lot for catalyst cost.In this thesis, we investigated hydrogenation of ethyl acetate as a model reaction. Copper was applied as an active component, aluminum and different alkaline-earth metal were added as additives to modulate the dispersion of Cu particles using a deposition-precipitation and heating stirring method. By adjusting the relative content of the active component and the additives as well as the calcination temperature of the catalyst precursor, the preparation parameters in the catalyst preparation process were optimized. The result showed excellent activity and selectivity to ethanol when the following conditions are met:using Cu(NO3)2·3H2O as a copper source, Al(NO3)3·9H2O and Mg(NO3)2·6H2O as additive, the molar ratio of n (Cu):n (Al):n (Mg)=9:0.5:1.5 and catalyst precursor calcination temperature was 300℃.Secondly, we optimized the reaction parameters further in the hydrogenation of ethyl acetate catalyzed by Cu9-Al0.5-Mgi.5 as a standard catalyst. Through modulating the reduction temperature, reaction temperature, hydrogen pressure, gas flow rate and liquid flow rate in the hydrogenation of ethyl acetate, we found that when the reaction conditions were as follows:1 g Cu9-Al0.5-Mgi.s catalyst, at the reduction temperature of 350℃, at the reaction temperature of 250℃, the gas flow rate of 60 ml/min and the liquid flow rate of 0.01 ml/min, hydrogen pressure of 4 MPa, the conversion of ethyl acetate could reach 97%, obtaining the selectivity to ethanol of 98%. Moreover, we investigated the catalyst life. After 210 h, the catalyst performance was still very stable without any loss in activity or selectivity.Finally, we used Cu9-Al0.5-Mg1.5 as catalysts in the hydrogenation of sec-butyl acetate and isopropyl acetate to produce sec-butyl alcohol and isopropyl alcohol, respectively. Under the optimized reaction conditions for the hydrogenation of ethyl acetate, the conversion and the selectivity for sec-butyl alcohol reached 94%, while the conversion of isopropyl acetate reached 99% with above 98% selectivity for isopropyl alcohol. These results indicate that the catalyst Cu9-Al0.5-Mg1.5 was active for acetate hydrogenation whice means the catalyst can be applied in a borader field.