萃取精馏分离乙醇碳酸二甲酯共沸物的研究.pdfVIP

摘 要 碳酸二甲酯 （DMC ）在农药、医药、高分子合成、燃料添加剂及溶剂中均 有广泛的运用，可代替光气、硫酸二甲酯等剧毒或者致癌物反应而生成重要的化 工产品。利用乙醇和DMC为原料合成碳酸二乙酯或者碳酸甲乙酯的过程中，均 涉及到乙醇和DMC 的分离。 本文主要对乙醇－DMC共沸物的萃取精馏分离方法进行了实验和模拟研究， 以获得高纯度和收率的乙醇和DMC产品。 首先，根据溶剂筛选的一些定性规则初选了几种溶剂，再采用UNIFAC基团 贡献法筛选出二甲苯、糠醛和氯苯三种合适的溶剂，且三者增大乙醇和DMC相 对挥发度的效果为：糠醛氯苯二甲苯。对糠醛和氯苯来说，消除乙醇－DMC 共沸所需要的最小溶剂浓度分别为0.25和0.35 。 然后，在理论预测的基础上，测定了二元和三元物系的气液平衡，并用Wilson 模型对实验数据进行关联，得到Wilson方程的二元交互作用参数。实验结果表明， 当溶剂摩尔含量为0.5时，糠醛和氯苯均能消除乙醇－DMC 的共沸，且糠醛增大 乙醇和DMC相对挥发度的效果优于氯苯。Wilson模型的计算结果与实验数据吻 合较好。 最后，采用Aspen Plus软件对连续萃取精馏分离乙醇－DMC 的过程进行了模 拟，并分别考察了双塔连续萃取精馏与单塔带侧线采出的连续萃取精馏两种方式。 双塔流程得到纯度分别为99.60%和98.90%的乙醇和DMC产品，收率分别为99.58% 和99.55% ；单塔流程得到纯度分别为99.60%和95.00% 的乙醇和DMC产品，收率 分别为99.60%和95.13% 。综合考虑分离效果和分离成本，单塔带侧线采出的连 续萃取精馏优于双塔连续萃取精馏。 关键词： 萃取精馏 碳酸二甲酯 乙醇 Aspen Plus ABSTRACT Dimethyl carbonate (DMC), widely used in pesticides, pharmaceuticals, polymer synthesis, fuel additives and solvents, can react to make some important chemical products, instead of the hyper toxic or carcinogenic substances like phosgene and dimethyl sulfate. Separation of ethanol and DMC will be inevitable in the synthesis of diethyl carbonate or methyl ethyl carbonate. Experimental and simulative researches on separation of ethanol-DMC using extractive distillation were carried out in this work to obtain the products of ethanol and DMC with high purities and yields. Firstly, several solvents were picked out according to some empirical and qualitative rules. Furthermore, dimethyl benzene, furfural and chlorobenzene were selected as appropriate solvents by UNIFAC group contribution method. And effects of the three solvents on enlarging the relative volatility of ethanol and DMC were as following: furfural chlorobenzene dimethyl benzene. To break the azeotrope, the minimum concentrations