Abstract:

Vacuum batch distillation experiments and simulation studies were conducted on a mixture of 1,4-butanediol (BDO) containing the acetal reactions. The experiments investigated the effects of operating pressure and reflux ratio on the removal efficiency of key impurities, 2-(4-hydroxybutyloxy)-tetrahydrofuran (BGTF) and γ-butyrolactone (GBL). Based on the impurity non-conservation such as BGTF, it was speculated that there was an acetal formation reaction during the distillation process. The vapor-liquid equilibrium data of BDO and the main impurity BGTF were measured at 3—10kPa, and the binary interaction parameters were regressed using the universal quasi-chemical model (UNIQUAC). A batch reactive distillation model was established, and kinetic parameters for the formation of reaction products, including 2-hydroxytetrahydrofuran (2-HTHF), BGTF, and GBL, were optimized. Based on these parameters, the effects of operating pressure and reflux ratio on the separation performance were calculated by Aspen. The results showed that when the operating pressure was in the range of 3—5kPa, the separation factor of BDO-BGTF was larger, and increasing the reflux ratio significantly improved the removal efficiency of BGTF. However, as the operating pressure increased, the effect of the reflux ratio on BGTF removal gradually diminished. When the operating pressure increased to 10kPa, an increase in the reflux ratio led to a decrease in BGTF removal efficiency. In conclusion, the best distillation effect was achieved under the conditions of 3kPa and reflux ratio of 10∶1. When the extraction ratio was 0.24, the content of BDO product was 99.65%, which met the requirements of qualified products. At this time, the removal rates of impurities BGTF and GBL were 88.30% and 85.37%, respectively.

Key words: vacuum batch distillation, 1,4-butanediol, 2-(4-hydroxybutyloxy)-tetrahydrofuran, vapor-liquid equilibria, acetal reaction, simulation, optimization

摘要：

对包含缩醛反应的1,4-丁二醇（BDO）混合物进行真空间歇精馏实验与模拟研究，考察了操作压力和回流比对混合物中关键杂质2-(4-羟基丁基氧)-四氢呋喃（BGTF）和γ-丁内酯（GBL）去除效率的影响，根据BGTF等杂质不守恒现象推测出精馏过程中存在缩醛反应；在3~10kPa压力下测定了BDO与主要杂质BGTF的汽液平衡数据，利用通用准化学理论模型（UNIQUAC）回归了二元交互参数。并建立了BDO体系的间歇反应精馏模型，优化得到了反应产物2-羟基四氢呋喃（2-HTHF）、BGTF与GBL生成的动力学参数，并在Aspen中模拟计算了操作压力和回流比对BGTF等杂质分离效果的影响。结果表明，操作压力为3~5kPa时，BDO-BGTF分离因子较大，增大回流比能显著提高BGTF的去除效率。随着操作压力的升高，回流比对BGTF的去除效果的影响逐渐减弱，操作压力为10kPa时，随着回流比由3∶1增大至6∶1和10∶1时，BGTF的去除效果反而变差。经实验验证，压力3kPa、回流比10∶1条件下，精馏效果最好。当采出比为0.24时，BDO产品质量分数为99.65%，满足合格品要求，此时杂质BGTF与GBL的去除率分别为88.30%和85.37%。

关键词: 真空间歇精馏, 1,4-丁二醇, 2-(4-羟基丁基氧)-四氢呋喃, 汽液平衡, 缩醛反应, 模拟, 优化