Abstract:

Caprolactam was prepared by Beckmann rearrangement using a spiral microchannel reactor. Through in-situ solvent vaporization and secondary flow technology, it overcomes the problems of high flow resistance in the microreactor of the high-viscosity reaction system, easy to cause local hot spots, and low production capacity. The effect of reaction temperature, solvent vaporization, helical size, pipe inner diameter, feedstock concentration, and flow rate on the conversion and selectivity of the reaction was investigated. The experimental results showed that the conversion rate could reach 100% and the selectivity was more than 99% with a 2 mm inner diameter spiral pipe, dichloroethane as solvent and an acid-oxime molar ratio at 1.1, a preheating temperature at 80℃, a rearrangement temperature at 90℃, a cyclohexanone oxime solution concentration at 10%—20%(mass), a retention time at 15 s, and a spiral diameter at 20 mm.20.2 g/min capacity for a single tube was realized, which corresponds to 9.7 t/a based on 8000 h per year. The results would provide theoretical guidance in the design and development of high-throughput and high-efficiency microchannel reactors. This study presents a solution for microreactors for highly viscous systems.

Key words: Beckman rearrangement, caprolactam preparation, microreactor, multiphase reaction, interface

摘要：

利用螺旋微通道反应器实现贝克曼重排制备己内酰胺。通过原位溶剂气化与二次流技术，克服了该高黏度反应体系在微反应器内流动阻力大、易造成局部热点、产能小等问题。探究了反应温度、溶剂气化、螺旋直径、管道内径、原料浓度、流量等因素对反应的转化率和选择性的影响。实验结果表明，在2 mm内径螺旋管道中，二氯乙烷为溶剂，酸肟摩尔比1.1前提下，预热温度80℃、重排温度90℃、环己酮肟溶液10%~20 %（质量分数），停留时间15 s、螺旋直径20 mm时，转化率可达100%，选择性达99%以上。同时实现了单管20.2 g/min的产能，按每年8000 h计算将达到9.7 t/a。本研究结果可为高通量、高效率的微通道反应器设计与开发提供理论指导，为高黏体系的微反应器提供解决方案。

关键词: 贝克曼重排, 己内酰胺制备, 微反应器, 多相反应, 界面