Study On The Process Of Catalytic Hydrogenation Of Isopropyl Acetate For Preparation Of Isopropanol And Ethonal

Isopropanol and alcohol are both important industrial chemicals, which have been widely used in the field of medication, pesticide, electronics, daily chemistry and gasoline additive. The main method to synthesize isopropanol currently in the world is through the hydration reactions of propylene, the process of which usually have two routes, i.e, the indirect hydration reactions of propylene and the dirct hydration reactions of propylene. There are mainly two methods of producing alcohol, the chemical reaction method and the fermentation method. The chemical reaction method to produce alcohol is through the hydration reaction of ethylene while the fermentation method is through the fermentation of the starch within the crops, both ways acquiring high production cost. So far there have merely been any reports and discoveries of synthesizing both alcohol and isopropanol at the same time through the hydrogenation of isopropyl acetate. Thus the preparation of highly active hydrogenation catalysts of isopropyl acetate is of great value in both practical applications and theoretical researches. This paper mainly describes the preparation of several series of copper-based catalysts and studies the practical effects during the hydrogenation reactions of isopropyl acetate from three aspects containing the preparation method, the optimization of reaction conditions and the modification of catalyst itself. We have carried out series of researches on the catalytic hydrogenation technology of isopropyl acetate aiming to prepare isopropanol and ethanol based on the copper-based catalysts through fixed-beds reactors. The main body of the study carried out includes the following aspects:(1) A series of copper-based catalysts were prepared in the hydrogenation reactions of isopropyl acetate through co-current co-precipitation method, sol-gel method and mechanical combination method. We investigated the properties and performance of the hydrogenation of isopropyl acetate under various catalyst preparation conditions. And the results show that the best catalysts can be obtained through calcinating the catalyst precursors, which were prepared using co-current co-precipitation method and precipitated under80℃, under450℃.Reacting under the temperature of230℃, pressure of7MPa, LHSV0.1h-1, the evaluation results show that the conversion ratio of isopropyl acetate is88.1%applying this kind of catalysts in the hydrogenation.(2) We have prepared series of copper-zinc catalysts under the best preparation conditions we have testified through experiments and studied the influences that the copper-zinc capacity and their mole ratio have on the catalyst activity. And we have also studied and screened how exactly the reaction conditions affect the catalyst property in order to select the best conditions out of them. The results indicate that there is little improvement in the conversion ratio of isopropyl acetate while the copper-zinc mass capacity occupies over60%. The conversion ratio of isopropyl acetate can reach over99.5%reacting under230℃,7MPa, LHSV0.1h-1, and the total yield of alcohol and isopropanol can reach over92%. This kind of catalyst can surprisingly maintain high activity even under low reaction temperature. Another experiment carried out also proves that reacting under180℃applying this kind of catalysts, the conversion ratio of isopropyl acetate can reach as high as96.4%. According to the capacity distribution within Cu-Zn-Al2O3catalyst, we prepared other catalysts as Cu-Cr-Al2O3, Cu-Co-Al2O3and Cu-Ni-Al2O3. The experiment results show that Cu-Co-Al2O3possesses the highest activity. Under the temperature of220℃, pressure of7MPa, LHSV0.1h-1, the conversion ratio of isopropyl acetate can reach97.3%with the total yield of isopropanol and alcohol reaching92.4%.(3) With the copper-zinc mass capacity occupying60%, mole ratio of which1:1.25, we add rare earth elements as Sm and Nd into the catalysts to study the influences they have on the catalyst properties. Under230℃, pressure ranging4-7MPa, LHSV0.2h-1, after comparing the reaction results with those samples unmodified with rare earth elements we have found out that applying the catalysts modified by Sm, the conversion ratio of isopropyl acetate has declined form96.9%～99.0%to89.7%～97.9%, the selectivity of isopropanol has went up from36.0%～38.2%to40.7%～47.9%. Applying the catalysts modified by Nd, the results show that the conversion ratio of isopropyl acetate has declined from96.9%～99.0%to91.7%～97.7%, the selectivity of isopropanol has went up from36.0%～38.2%to44.8%～52.5%.(4) We have also tested the commercial catalysts XM-1during our hydrogenation reactions under180～240℃, pressure of7MPa, LHSV0.1h-1. Comparing the evaluation results with those using our own catalysts under exactly the same conditions, the conversion ratio with the commercial catalysts is98.4%-99.6%, that with our self-made Cu-Zn catalysts is98.1%～98.8%. The total yield of isopropanol and ethanol with the commercial catalysts is93.3%～98.3%, while that of the self-made catalysts is87.0%-96.6%.