摘要
对苯二甲酸(Terephthalic Acid)作为一种重要的化工原料被广泛地应用于石油化工生产当中。随着我国聚酯产业的发展，PTA(Purified TerephthalicAcid)的产量也逐年上升。然而，现行的PTA生产装置多采用Amoco工艺。这种工艺的生产过程中会产生大量的废料。这些废料按各自的产生途径分为氧化残渣、精制母固残渣和水池废料。这些废料成分复杂且具有毒性，如不处理会对环境造成巨大的影响。同时，废料中含有大量有用的物质，如不得到综合回收利用，也是对资源的浪费。本文从充分利用资源和保护环境的目的出发，对残渣的分离、回收及再利用方法进行了研究。
在本实验室以前的工作基础之上，本文进一步对氧化残渣中有机物、精制母固残渣及水池废料的分离回收方法进行了探讨并选择氯仿作为残渣萃取分离的主要工作溶剂。相关地，在精确测得的溶解度数据的基础上，应用UNIFAC模型对相关热力学体系进行了研究，根据不同苯羧酸溶解度的特点提出了分离工艺的基本原则，进而讨论了分离回收废料中混合苯羧酸的工艺条件并用实验进行了证实。最后，还对利用回收所得的TA制备较低聚合度的聚酯树脂工艺进行了初步探讨和研究。
首先，建立了一套带激光监视系统可程序控温的合成法溶解度测定装置，用于测定固液两相达平衡速度较快的物系的溶解度。由晶体管激光发生器、光电转换器和光强数码显示仪组成的激光监视系统能及时了解物系的溶解状况，并准确地判断溶解终点，从而大幅度提高了所测数据的准确性。对标准物系溶解度测定结果表明，测定误差均小于3％。
另外，对于固液两相达到平衡的速度较慢的物系又建立了一套平衡法溶解度测定装置。激光监视系统被用来判断固液相分离程度。对标准物系溶解度的测定结果表明，实验测定值与文献值符合良好，测定误差均小于5％，从而说明本文由平衡法测定的溶解度数据也是准确可靠的。
确定分离工艺模型前需要对邻苯二甲酸、对苯二甲酸、间苯二甲酸、苯甲酸、对甲基苯甲酸和对羧基苯甲醛六种苯羧酸在室温至58℃温度范围内各自与氯仿所形成的二元体系固液相平衡溶解度进行精确测定。测定结果发现对苯二甲酸及其同分异构体在氯仿中的溶解量非常小，可以认为它们在氯仿中不溶解。但苯甲酸和对甲基苯甲酸溶解量比较大，因此可以用氯仿作溶剂实现一元苯羧酸和二元苯羧酸的分离。为了进一步分离可溶在氯仿中的两种
x叮【、1大学硕十学位论文
一元苯簸酸，用合成法准确测得了苯甲酸－氯仿、对甲基苯甲酸一氯仿以及
苯甲酸一对甲基苯甲酸一氯仿三元体系在 30C、40C和 50℃下总共 5个固
液物系的溶解度，合计82个数掘点。在测得的固液相平衡数据的基础上，针
对所研究的 5个固液体系，采用 UNIF／＼C模型对数据进行拟合。惜鉴61）人的
研究方法，将苯甲酸、对甲基苯甲酸整个分于定义成新基团。拟合时，氯仿
的面积参数和体积参数使用文献值，新定义基团的面积参数和体积参数以及
氯仿、苯甲酸、对甲基苯甲酸的交互作用参数则由实验数据回归得到。
在模型参数回归中，首先根据所测定的二元体系溶解度实验数据，由
￡
Nelder－Mead扩充Simplex单纯形法用苯甲酸一氯仿和对甲基苯甲酸一氯仿
两个二元体系溶解度数据对所定义的两个新基团的面积参数和体积参数以
及新基团与CHC13基团之间的交互作用参数进行了优化回归。再用回归得到
的参数，对2个二元体系的溶解度进行反算，与实验结果结果符合良好。再
用己获得的参数由实验测定的氯仿－苯甲酸－对甲基苯甲酸混合溶质三元体系
在30aC下的溶解度数据回归得到了B。VMBA交互作用参数，并由模型对此
三元体系在30”C固液相平衡进行了反算，对40C和 50t下的三元体系溶解
度进行预测，反算值和预测值均与实验值符合良好。拟合结果证明UNIFAC
模型能很好地应用于含苯竣酸的固液相平衡体系，可以作为聚酯生产废渣处
理相关组分溶解度数据预测的数学模型。最后依据这个数学模型绘制了氯仿
－苯甲酸－对甲基苯甲酸三元体系在 30T？、40℃和 50aC下的三元体系相图，作
为在氯仿溶剂中苯甲酸、对甲基苯甲酸分离口收工艺条件确定的理论根据。
在上述固液相平衡研究的基础上，制定了用溶剂分离各种残渣的实验方
案。依次讨论了从去除了钻、锰催化剂的氧化残渣中革取分离一元苯骏酸和
二元苯竣酸氯仿的用量，进一步分离苯甲酸和对甲基苯甲酸的工艺操作条
件。讨论了从精制母固残渣中分离对甲基苯甲酸的工艺条件。讨论了水池废
庐 料脱除机械杂质后，提纯对苯二甲酸的工艺条件。随后进行了三种残渣分
离的实验，得到了纯度高的分离产品。
本文最后，建立了一套实验室制备PET聚酯的装置。用本文提出的工艺
模型回收所得的对苯二甲酸和乙二醇反应，制得了具有一定聚合度的PET聚
酯?
As a very important material ,terephthalic acid is widely used in chemical industry .The most important use of it is purified to make polyester with ethynyl glycol. With the development of polyester industry,the production of purified terephthalic acid(PTA) has increased intensively. And the problem caused by the PTA residues has become more and more serious. According to various originations,the PTA residues are divided into there kinds which are respectively called the oxidation residue, the residue from the purification process and the residue from the effluent setting chamber. For the purpose of environmental protection and sufficient utilization of natural resources, it is necessary to separate, recover and reuse the residues.This work is concentrated on the technologic model of seperating the PTA residues using solvents.
First of all,a laser monitoring observation system and programmed heating apparatus are set up to determine the solubilities of the systems which have quick solid-liquid equilibria by synthetic method. As well, another apparatus is set up to determine the solubilities of the systems which have slow S-L-E . The solubilities of 2 binary systems and 3 ternary systems are precisely determined. The binary systems include benzoic acid -chloroform system and p-toluic acid -chloroform system.And the 3 ternary systems are benzoic acid-p-toluic
acid-chloroform co-solute system at 30 ,40 and50 . Totally 82
experimental points are obtained. Through experiments,it is also proved that the solubilities of terephthalaldehydic acid and terephthalic acid & its isomeric compounds in chloroform are tremendously small,in other words, they do not solve in chloroform.
On basis of the experimental data, a modified UNIFAC model is set up by defining 2 new functional groups, which are BA(Benzoic Acid),and MBA(p-Toluic Acid) .In this modified UNIFAC model, group volume -7
parameters, group surface-area parameters and group interaction parameters are optimized. This model can perfectly predict the experimental solubilities. The
S-L-E of chloroform-p-toluic acid-benzoic acid ternary system at 50 is predicted using the BA/MBA group interaction parameters regressed from the solubilities of this ternary system at30and 40 together with the binary
interaction parameters. The results also fit in well with the experimental values.Three ternary-system phase diagrams are drawn according to the predicted data by the modified UNIFAC model.
Then,a technologic model is established to separate the mixed benzene carboxylic acids in the PTA residues mainly by using chloroform. Benzoic acid, terephthalic acid are recovered from the oxidation residue, terephthalic acid is recovered from the residue from the purification process and the residue from the effluent setting chamber.The recovered benzene carboxylic acids have fairly high purities.In the future,this technologic model for separating mi benzene carboxylic acid mixtures can be used in the engineering design of PTA residue recoveries.
In the last part of this thesis,a set of laboratory apparatus for synthesizing the polyester (PET) is set up.A kind of polyester is produced from the synthesis of the terephthalic acid recoverd by the mentioned technologic model and ethylene glycol. The PET product has a relatively high molecular weight, which demonstrates that the recovered terephthalic acid has a high purity and the technologic model for separating benzen carboxylic acid mixtures presented in this thesis is feasible.
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