Experimental study on the formation mechanism of hydrolyzed chlorine as a by-product during HDI preparation

doi:10.11949/0438-1157.20241092

Abstract

Abstract:

Hexamethylene diisocyanate (HDI) is a pivotal chemical primarily synthesized through the photogasification reaction of hexamethylenediamine and phosgene. In isocyanate products, the content of hydrolyzed chlorine serves as a vital indicator for quality control, significantly impacting the product's stability and performance. This study delves into the formation mechanism of hydrolyzable chlorine by-products during the preparation of HDI. We analyzed the influence of oxygen content, heating time, and superheating temperature on the types and quantities of hydrolyzable chlorine, and subsequently proposed corresponding control strategies. Experimental results reveal that oxygen in the amine solution notably affects ethylenediamine. Specifically, during the heating process, oxygen accelerates the formation of hydrolyzed chlorine. Pretreatment of the amine solution to remove oxygen can effectively mitigate the formation of hydrolyzed chlorine. Additionally, the superheating temperature of hexamethylenediamine should be carefully balanced between acceptable levels of hydrolyzed chlorine and the risk of equipment blockage, thereby minimizing the production of hydrolyzed chlorine without causing equipment issues.

Key words: hexamethylene diisocyanate, oxygen, reaction time, overheating temperature, hydrolyzed chlorine

摘要：

六亚甲基二异氰酸酯（HDI）是一种重要的化学品，主要通过己二胺与光气之间的光气化反应合成。在异氰酸酯产品中，水解氯的含量是衡量其质量的关键指标之一，对产品的稳定性和性能具有举足轻重的影响。深入探讨HDI制备过程中副产物水解氯的生成机理，细致分析了氧气含量、加热时间以及过热温度等因素对水解氯种类及含量的具体影响，并据此提出了相应的控制策略。实验结果显示，胺溶液中氧气的存在对己二胺影响显著，氧气在胺受热过程中加速了水解氯的生成。因此，对胺溶液进行除氧预处理，可有效减少水解氯的生成量。同时，在确定己二胺的过热温度时，需在可接受的水解氯含量范围与避免设备堵塞现象之间进行合理权衡，力求在不引发设备堵塞的前提下，最大限度地减少水解氯的生成。

关键词: 六亚甲基二异氰酸酯, 氧气, 反应时间, 过热温度, 水解氯

CLC Number:

TQ 032.4

Jianyong MAO, Jijun GE, Pan XU, Rongshan BI. Experimental study on the formation mechanism of hydrolyzed chlorine as a by-product during HDI preparation[J]. CIESC Journal, 2025, 76(S1): 384-392.

毛建拥, 葛纪军, 徐盼, 毕荣山. HDI制备过程中副产物水解氯生成机理实验研究[J]. 化工学报, 2025, 76(S1): 384-392.

Figures/Tables 9

Table 1 Sources and purities of experimental materials

分子式	化学名称	CAS号	供应商	纯度/% (质量分数)
C₆H₁₆N₂	己二胺	124-09-4	英威达尼龙化工(中国)有限公司	99.90
CH₄O	甲醇	67-56-1	—	99.80
C₃H₆O	丙酮	67-64-1	—	99.80
N₂	氮气	7727-37-9	—	—
AgNO₃	硝酸银	7761-88-8	—	99.80
NaCl	氯化钠	7647-14-5	—	99.80
COCl₂	光气	75-44-5	山东新和成股份有限公司	—

Fig.1 Experimental device diagram of amine solution heating

Fig.2 HDI pilot production route

Fig.3 The gas chromatograms of the products after the reaction of amine solution in normal heating (a), heating in air (b) and deoxygenation heating (c) were obtained respectively

Fig.4 Gas chromatogram of HDI products without/with oxygen in pilot production

Fig.5 The effect of reaction time on the content of 3,4,5,6-tetrahydro-2H-azepine/hexamethylenediamine in different oxygen content environment

Fig.6 Effect of reaction time on the content of 2,3,4,5-tetrahydro-1H-azepin-1-carbonyl chloride under pre-deoxygenation / deoxygenation conditions

Fig.7 The gas chromatograms of HDI products at different superheating temperatures

Fig.8 Effect of overheating temperature on impurity content

References 30

1	刘士民, 王培学, 邓友全. 非光气制异氰酸酯绿色过程[J]. 中国科学: 化学, 2020, 50(2): 235-244.
	Liu S M, Wang P X, Deng Y Q. Green non-phosgene process for manufacturing isocyanates[J]. Scientia Sinica Chimica, 2020, 50(2): 235-244.
2	Lenzi V, Crema A, Pyrlin S, et al. Current state and perspectives of simulation and modeling of aliphatic isocyanates and polyisocyanates[J]. Polymers, 2022, 14(9): 1642.
3	张曼, 周静, 张亚芳, 等. 聚氨酯中肟封闭芳香族异氰酸酯单体的液相色谱分析[J]. 聚氨酯工业, 2019, 34(4): 42-44.
	Zhang M, Zhou J, Zhang Y F, et al. Liquid chromatography analysis of oxime-blocked aromatic isocyanate in polyurethane[J]. Polyurethane Industry, 2019, 34(4): 42-44.
4	Cao Y, Li H Q, Qin N B, et al. Kinetics of the decomposition of dimethylhexane-1, 6-dicarbamate to 1, 6-hexamethylene diisocyanate[J]. Chinese Journal of Chemical Engineering, 2015, 23(5): 775-779.
5	Braun H. Methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI)[J]. Industrial Arene Chemistry: Markets, Technologies, Sustainable Processes and Cases Studies of Aromatic Commodities, 2023, 3: 1525-1574.
6	宋春梅, 薛海丽, 庄小璐, 等. 异佛尔酮二异氰酸酯自聚产物的¹³C-NMR研究[J]. 高分子学报, 2006, 37(5): 660-665.
	Song C M, Xue H L, Zhuang X L, et al. The ¹³C-NMR analysis of polyisocyanurate made from isophorone diisocyanate[J]. Acta Polymerica Sinica, 2006, 37(5): 660-665.
7	Wang X, Yang X, Zheng S Q. Thermal behaviors and kinetic analysis of dicyclohexylmethane-4, 4'-diisocyanate (HMDI)[J]. Thermochimica Acta, 2024, 733: 179676.
8	Wang H R, Cao L, Wang X L, et al. Effects of isocyanate structure on the properties of polyurethane: synthesis, performance, and self-healing characteristics[J]. Polymers, 2024, 16(21): 3045.
9	Rother D, Schlüter U. Occupational exposure to diisocyanates in the European union[J]. Annals of Work Exposures and Health, 2021, 65(8): 893-907.
10	Mouren A, Avérous L. Sustainable cycloaliphatic polyurethanes: from synthesis to applications[J]. Chemical Society Reviews, 2023, 52(1): 277-317.
11	Galbis J A, de Gracia García-Martín M, Violante de Paz M, et al. Synthetic polymers from sugar-based monomers[J]. Chemical Reviews, 2016, 116(3): 1600-1636.
12	Bi R S, Yan K J, Yang H X, et al. Simulation and optimization of the thermally coupled reactive distillation column for producing toluene diisocynate[J]. AIChE Journal, 2023, 69(1): e17648.
13	马德强, 丁建生, 宋锦宏. 有机异氰酸酯生产技术进展[J]. 化工进展, 2007, 26(5): 668-673.
	Ma D Q, Ding J S, Song J H. Progress in the production of organic isocyanates[J]. Chemical Industry and Engineering Progress, 2007, 26(5): 668-673.
14	Hou Z T, Chen H F, Mao J Y, et al. Novel atomization-assisted phosgenation for TDI synthesis from TDA: a theoretical study on single droplet reactivity[J]. Chemical Engineering Science, 2023, 280: 119018.
15	Waibel K A, Nickisch R, Möhl N, et al. A more sustainable and highly practicable synthesis of aliphatic isocyanides[J]. Green Chemistry, 2020, 22(3): 933-941.
16	Bi R S, Yang H X, Yan K J, et al. Synthesis of sustainable production chains for phosgene-related byproducts[J]. Journal of Cleaner Production, 2022, 374: 133979.
17	Wen F, Hu M, Li Y, et al. The production of methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) at Wanhua Chemical Group (case study)[J]. Industrial Arene Chemistry: Markets, Technologies, Sustainable Processes and Cases Studies of Aromatic Commodities, 2023, 3: 1575-1609.
18	Oenema J, Liu H R, De Coensel N, et al. Review on the pyrolysis products and thermal decomposition mechanisms of polyurethanes[J]. Journal of Analytical and Applied Pyrolysis, 2022, 168: 105723.
19	谭伟民, 王黎, 狄志刚, 等. 生物基五亚甲基二异氰酸酯(PDI)三聚体的制备及性能研究[J]. 涂料工业, 2020, 50(11): 38-44.
	Tan W M, Wang L, Di Z G, et al. Preparation and properties of bio-based pentamethylene diisocyanate(PDI)trimer[J]. Paint & Coatings Industry, 2020, 50(11): 38-44.
20	周玲, 张建伟, 盛振晗, 等. TDI内在质量对其应用的影响[J]. 聚氨酯工业, 2016, 31(5): 44-46.
	Zhou L, Zhang J W, Sheng Z H, et al. The influence of TDI quality on its application[J]. Polyurethane Industry, 2016, 31(5): 44-46.
21	袁纪武. MDI精馏精制和降低水解氯的研究[D]. 青岛: 青岛化工学院, 1999.
	Yuan J W. Study on refining and reducing hydrolyzed chlorine by MDI distillation[D]. Qingdao: Qingdao Institute of Chemical Technology, 1999.
22	池俊杰, 贾利亚, 李晓峰, 等. 降低异氰酸酯水解氯含量的研究进展[J]. 化学推进剂与高分子材料, 2022, 20(1): 25-31.
	Chi J J, Jia L Y, Li X F, et al. Research progress in reducing hydrolyzable chlorine content in isocyanates[J]. Chemical Propellants & Polymeric Materials, 2022, 20(1): 25-31.
23	Albini A, Fagnoni M. Photochemically-generated Intermediates in Synthesis[M]. New York: John Wiley&Sons, 2013.
24	俞勇, 崔学磊, 郭耀允, 等. 一种多异氰酸酯组合物及其制备方法和应用: 112592457A[P]. 2021-04-02.
	Yu Y, Cui X L, Guo Y Y, et al. Preparation and application of a polyisocyanate composition: 112592457A[P]. 2021-04-02.
25	王文博, 张宏科, 姚雨, 等. 一种制备无色或浅色多异氰酸酯的方法: 106554293A[P]. 2017-04-05.
	Wang W B, Zhang H K, Yao Y, et al. A method for preparing colorless or light-colored Isocyanate: 106554293A[P]. 2017-04-05.
26	俞勇, 尚永华, 李建峰, 等. 光化反应制备多异氰酸酯的方法以及制备水性聚氨酯树脂的方法: 110511163A[P]. 2019-11-29.
	Yu Y, Shang Y H, Li J F, et al. Method for preparing polyisocyanate by photochemical reaction and waterborne polyurethane resin: 110511163A[P]. 2019-11-29.
27	郑世清, 谭心舜, 谈明传, 等. MDI同分异构体及水解氯分离的研究(Ⅰ)实验研究[J]. 青岛化工学院学报(自然科学版), 2001, 22(1): 24-26.
	Zheng S Q, Tan X S, Tan M C, et al. The separation process of MDI isomer and hydrolysis (Ⅰ): The experiment study[J]. Journal of Qingdao Institute of Chemical Technology, 2001, 22(1): 24-26.
28	道森, 罗恩康, 纳夫滋格, 等. 降低甲苯二异氰酸酯中可水解氯化物含量的方法: 1064074A[P]. 1992-09-02.
	Dawson R D, Roancon S B, Navtzger J L, et al. Methods for reducing the hydrolyzable chloride content of toluene diisocyanate: 1064074A[P]. 1992-09-02.
29	张宏民, 吴雪峰, 张宏科, 等. 一种脱氯剂及其制备方法与降低异氰酸酯氯含量和色度的应用: CN112430295A[P]. 2021-03-02.
	Zhang H M, Wu X F, Zhang H K, et al. Preparation of dechlorination agent and its application in reducing chlorine content and colority of isocyanate: 112430295A[P]. 2021-03-02.
30	李同和, 尚永华, 蒙萌, 等. 一种气相法制备低水解氯含量异氰酸酯的方法: 112824376A[P]. 2021-05-21.
	Li T H, Shang Y H, Meng M, et al. Method for preparing isocyanate with low hydrolytic chlorine content by gas phase method: 112824376A[P]. 2021-05-21.

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