摘要
邻苯二甲酸二辛酯(DOP)的合成过程分苯酐(PA)和异辛醇(2-EH)反应生成邻苯二甲酸单辛酯(MEHP)、MEHP和2-EH反应生成DOP两步进行,其中后一步是关键控制步骤。针对MEHP和2-EH之间的可逆反应,采用基团贡献法对反应焓变和熵变进行了理论计算;并采用间歇实验测定了无外加催化剂条件下的反应平衡和易挥发组分2-EH与水的汽液平衡,以及以钛酸四丁酯为催化剂的反应动力学。通过热力学实验确定了433.15~493.15K时反应平衡常数为4.79~8.93,回归得到的反应焓为17.91kJ/mol、反应熵为54.64J/(K·m01),与基团贡献法计算值基本相符;活度系数Redlich.Kister方程能较好地关联2-EH和水的汽液平衡数据。动力学研究结果表明高转化率下DOP水解反应影响不可忽略,MEHP和2-EH间的正、逆反应都符合二级反应规律,回归得到453.15-493.15K时正反应活化能为83.49kJ/mol,指前因子为1.75×10^7kg/(mol。min)。
The synthesis of dioctyl phthalate(DOP) involves mono-(2-ethylhexyl) phthalate(MEHP) formation firstly by phthalic anhydride(PA) with 2-ethyl hexanol(2-EH) and further esterification between MEHP and 2-EH to generate DOP, and the second reaction is reversible and the controlling step. Since MEHP conversion is usually demanded to be over 99.5%, the influence of DOP hydrolysis cannot be neglected. The thermodynamic properties were calculated by Benson, Ducros and Ruzicka-Domalski group contribution methods. The vapor-liquid equilibrium composition and reaction equilibrium constants of the controlling reaction as well as the kinetics with tetrabutyl titanate as catalyst were investigated experimentally in batch reactor. The result of thermodynamic experiments showed that the enthalpy and entropy of the reaction between MEHP and 2-EH were 17.91 k J/mol and 54.64 J/(K·mol) respectively, and this reaction was endothermic with increasing entropy which was consistent with the theoretical calculation result. The activity coefficient of water and 2-EH in this reactive system was fitted well using Redlich-Kister equation. The kinetic model of reversible reaction between MEHP and 2-EH was established, both the forward and backward reaction can be treated as second-order reactions, and parameter regression showed that the activation energy and pre-exponential factor of the forward reaction were 83.49 k J/mol and 1.75×107kg/(mol·min) respectively.
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
2015年第5期385-392,共8页
Chemical Reaction Engineering and Technology
基金
国家自然科学基金(21176070)