The Process Design Of N-Butyl-acetate With Reactive Distillation

The industrial synthesization of n-butyl acetate with reactive distillation was investigated by experiments and Aspen Plus, and a set of equipments is designed at the capability of 6kt/a. In this process, the catalyst of acidic cation exchange resin was used as packing for taking place sulfuric acid to finish the process of reaction and separate simultaneity. Finally, coarse n-butyl acetate was produced continually in the bottom stream of packed column which shows the predominance than old multi-step process.Results showed that the packed column was composed of 14 theoretic trays (including partial condenser and reboiler). And the streams of feed and organic reflux are fed on the 4th tray. On the condition, i.e., splitter temperature is 20℃, organic reflux temperature is 105℃, the flux, temperature, and pressure of feed stream which just includes n-butanol and acetic acid is 0.1608 kmol·h^-1, 105℃, 0.0842MPa separately, the mole ratio of n (Bu) : n (Ac) = 1 : 1 is optimum, and one mixing feed stream of n-butyl and acetic-acid is better than two pure streams. It was shown that the mole ratio, manner and position of the feed, the position of organic reflux, and flow rate of top reflux were all affected the quality of production. Coarse n-butyl acetate of 95.70% was produced at the bottom stream, and azeotrope of water was left at the top.The scale-up of reactive distillation was modeled with ASPEN PLUS 10.2 based on pilot-plant. Results show that the column distribution, composition distribution and reaction rate distribution was consistent with experiments. The process parameters of reactive distillation were computed. Two parallel columns were needed to perform the process, and the capacity of single column was 3kt/a. The column with dimension ofΦ600×13600 and 14 trays was divided into three segments, i.e., distilling, reactive distilling and stripping sections which was 1440mm, 5040mm and 1620mm separately. The dimension of kettle wasΦ1200×1600, which had bigger volume for favor of stable.The efficiency of this process is better than sulfur acid method, so the investment is lower than it. The cost of catalyzer is higher than sulfur acid, however, the costs of material and steam, equipments maintaining and depreciation are all lower than sulfur acid method. So the total produce cost is lower RMB 350yuan/t than sulfur acid method. It was easy to produce higher quality n-butyl acetate than sulfur acid method due to the purity reaches 94% from reactive distilling column and no side reaction.