【作者】 张虹；

【导师】 张凤宝；

【作者基本信息】 天津大学 ， 化学工程， 2008， 硕士

【摘要】 在碱性水介质中用空气氧化对硝基甲苯邻磺酸制备4,4’-二硝基二苯乙烯-2,2’-二磺酸(DNS)是工业上生产染料中间体4,4’-二氨基二苯乙烯-2,2’-二磺酸(DSD)的关键步骤。长期以来仅知道DNS会在一定条件下发生降解反应,但对其反应动力学和反应机理的研究很不充分。本文从4,4’-二硝基二苯乙烯-2,2’-二磺酸降解反应机理及动力学研究和DNS生产工艺(空气流量)优化三个方面展开论述。采用自制的4L反应釜,对DNS降解反应过程进行小试研究。采用高压液相色谱对反应进行动力学跟踪,建立了不同空气流量下的4,4’-二硝基二苯乙烯-2,2’-二磺酸降解反应的动力学模型,求取了反应级数、速率常数、反应活化能、指前因子等动力学参数,并采用数学模型与实验结合的方法分析了降解速率随反应时间、温度、碱值等的变化规律。通过考察反应体系中氧气分压对降解速率的影响,推测了4,4’-二硝基二苯乙烯-2,2’-二磺酸(DNS)降解反应的机理: DNS在碱性水溶液中发生歧化反应,该反应是可逆的,氧气的存在会在一定程度上促进逆向反应,抑制正向反应。氧气的存在在一定程度上会抑制DNS发生降解反应。研究了空气流量对降解速率的影响,发现在一定流量范围内可以适当降低空气流量,从而降低能耗,减少生产成本。更多还原

【Abstract】 The air oxidation of p-nitrotoluene-o-sulfonic acid (NTS) under aqueous alkaline conditions to prepare 4,4’-dinitrostilbene-2,2’-disulfonic acid (DNS), which is the key procedure in the synthesis of 4,4’-diaminostilbene-2,2’-disulfonic acid (DSD). DSD is a valuable intermediate of fine chemicals. By now, just know that 4,4’-dinitrostilbene-2,2’-disulfonic acid will breakdown under some conditions and little know about kinetics and mechanism of the degradation. Therefore, the objectives of this paper include: the investigation of mechanism and kinetics of the degradation and the optimization of conventional process(air flow).The small scale experiments of DNS degradation process were performed with a home-made reactor with the volume of 4L. By monitoring the reactions with HPLC, the kinetic models of the degradation of 4,4’-dinitrostilbene-2,2’-disulfonic acid under differernt air flow were established, and the reaction order, reaction constant, activation energy and frequency factors were obtained. In addition, the change rules of reaction time, temperatures, hydroxide concentration were investigated by combining the mathematical model and experimental data.Base on carefully investigating the effects of oxygen partial pressure on the degradation ratio, the possible mechanism explaining the degradation of DNS is speculated: The degradation of DNS is a disproportionation reaction under aqueous alkaline conditions as well as reversible reaction. The oxygen in the reaction system will repress the positive reaction, but promote the negative reaction.Base on analysis the effect of air flow on the reaction’s rate, discover that appropriately lowering the flow of air within certain limits, will reduce energy consumption and costs.更多还原