苯胺与甲醛合成二氨基二苯甲烷反应过程的基础研究
文献类型：学位论文
| 作者 | 王晨晔 |
| 学位类别 | 硕士 |
| 答辩日期 | 2012-05-23 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 张懿 ; 李会泉 |
| 关键词 | 苯胺 二氨基二苯甲烷 薄层层析法 动力学 热力学 |
| 其他题名 | Study on the Synthesis of Methylenedianiline from Aniline and Formaldehyde |
| 学位专业 | 化学工艺 |
| 中文摘要 | 二苯甲烷二异氰酸酯(MDI)是生产聚氨酯的重要原料，目前工业上主要采用光气法生产。随着环保要求的日益提高，发展非光气法制备MDI正在成为绿色化学化工的前沿和行业绿色化升级的迫切需求。在光气与非光气路线中，二氨基二苯甲烷（MDA）均为生产MDI的重要原料，但现有生产方法仍存在选择性低、原料配比高、副产物体系复杂等问题。因此，本文以苯胺与甲醛缩合反应制备MDA为背景，系统开展了反应副产物分析、工艺条件优化、过程动力学及热力学研究。研究结果将为反应产物调控、最佳反应条件确定、反应器优化设计提供理论依据。主要研究内容与进展如下： (1)采用氯仿体系为洗脱剂，利用层析柱结合薄层层析对反应过程副产物进行分离和定性，在优化条件下得到3种副产物，采用质谱分析方法确定3种副产物分别为N,N’-亚甲基二苯胺，MDA三聚体以及MDA四聚体；进一步使用同位素示踪方法揭示了副产物生成机理为SN2取代反应。 (2)开展了苯胺与甲醛缩合反应制备MDA工艺条件优化研究，考察了转位时间、转位温度、苯胺和甲醛配比、以及催化剂盐酸用量对反应的影响规律，在优化工艺工艺条件下：n(苯胺)/n(甲醛)=3，反应温度90 ℃，反应时间1 h，n(HCl)/n(苯胺)=1.5，得到MDA最高收率73.4%。 (3)开展了苯胺与甲醛反应动力学研究，通过等转化率法对两步反应进行模型简化，通过积分法确定反应级数为1，指前因子为-4.69，反应活化能为39.00kJ/mol；建立了苯胺与甲醛反应动力学模型，MDA生成符合(1-(1-α)1/3)2=kt 机理模型，其中k=10075.08×exp(-39.00/RT)。 (4)对苯胺和甲醛反应体系进行热力学分析研究。结果表明生成中间产物、目标产物MDA以及生成三环和四环低聚物的过程均为强放热反应；并且该过程也是一个自发反应过程，根据各反应的吉布斯自由能比较发现，生成MDA的主反应进行程度最大，随着温度的升高，生成副产物p-MDA和tetra-MDA反应的自发程度减小。 |
| 英文摘要 | Methylene diphenyl-4, 4’-diisocyanate (MDI), which is a kind of raw material, is mainly synthesized through phosgene route in the industrial production. For the extreme toxicity of phosgene, significant attempts have been made to develop non-phosgene routes. Methylenedianiline (MDA) is used as a main raw material in both phosgene and none-phosgene routes. There are still many obstacles existed in the MDA production, such as low selectivity. Based on catalytic synthesis of (MDA) from aniline and formaldehyde over HCl catalyst, some key issues were systematically researched in the dissertation, such as optimization of reaction condition, qualitative and quantitative investigations on by-products, kinetic and thermodynamic analysis. The following achievements and progress were exhibited: (1) To get a better understanding of the synthesis reaction and promote the MDA selectivity, the chromatographic column combined with thin-layer chromatography is used to separate and qualitatively analyze by-products. Under the optimum conditions, three components are effectively separated from mixtures. Qualitative analyses is completed with the help of mass spectrometry. Meanwhile, some possible reaction mechanisms are proposed. Isotope labeling experiments using the deuterium-labeled HCl with high performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-MS) characterizations established that this reaction proceeds through SN2 reaction mechanism. (2) Then the process conditions of synthesis of MDA from aniline and formaldehyde were studied in detail. The effects of reaction temperature, reaction time, molar ratio of reactants and the content of catalyst have been studied, The results showed that the yield of MDA could reach 73.4%n under optimum conditions of 90 ℃, 1 h, n (aniline)/ n (formaldehyde)=3/ 1 and n (HCl)/ n (aniline)=1.5/ 1. (3) The kinetics of the reaction between aniline and formaldehyde were studied by real-time sampling. The calculation the kinetic parameters was based on the isoconversional method. It is well known that the condensation of aniline consists of two consecutive steps, and the two steps could be simplified to a kinetic model in which middle reaction course could be ignored. After calculation, the formation of MDA was in accordance with (1-(1-α)1/3)2=kt equation, in whichk is 10075.08×exp(-39.00/RT). (4) The thermodynamics analysis of the reaction system of aniline and formaldehyde showed that the main reaction and two side reactions, the formation of oligomeric isocyanates with functionalities of 3 (p-MDA) and 4 (tetra-MDA), were exothermal. In addition, the synthesis of MDA was more competitive than the synthesis of other products in thermodynamics. |
| 语种 | 中文 |
| 公开日期 | 2013-09-25 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1837]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 王晨晔. 苯胺与甲醛合成二氨基二苯甲烷反应过程的基础研究[D]. 中国科学院研究生院. 2012. |
入库方式： OAI收割
来源：过程工程研究所
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