高分子量聚丙二醇在微通道反应器中的制备

doi:10.11949/0438-1157.20221630

摘要/Abstract

摘要：

高分子量聚醚多元醇应用广泛，但用传统的半连续釜式法制备不仅反应热风险大，而且反应时间漫长。采用微通道反应器(MCR)具有传热效率高、过程安全的特点，但反应物料黏稠、放热量大也使聚醚多元醇的分子量难以提高。本研究以双金属氰化络合物(DMC)为催化剂、正己烷为溶剂，在MCR中进行了环氧丙烷的开环聚合，制备出了分子量在2000~8000之间的聚丙二醇(PPG)。通过对流速、通道长度、温度和进料方式影响的考察，发现在停留时间足够长时，产品分子量基本等于理论分子量；当起始剂流速固定，单体流速增加时，分子量分布(MWD)先变宽再变窄；当管长较长时，分子量较高且MWD较宽；温度升高会使聚合反应的诱导期缩短；分段进料比一段进料更易制备高分子量PPG，但MWD变宽。这些均可用DMC催化的环氧丙烷的开环聚合机理和物料在MCR中微观混合强度的变化来解释。微观混合强度越低，聚合反应中链转移与链增长的速率比越小，聚合物的分子量分布也越宽。

关键词: 微通道, 开环聚合, 制备, 聚丙二醇, 高分子量, 聚合

Abstract:

High molecular weight polyether polyols are widely used. However, there is not only a large risk of reaction heat, but also a long reaction time in its traditional production process by using the semi-continuous reactor. The microchannel reactor (MCR) has the characteristics of high heat transfer efficiency and process safety, but the viscous material and high reaction heat release make it difficult to produce the high molecular weight polyether polyols. In this work, using double metal complex (DMC) as catalyst and n-hexane as solvent, the ring-opening polymerization of propylene oxide (PO) was carried out in MCR. Polypropylene glycol (PPG) with molecular weight ranging from 2000 to 8000 was prepared. Effects of reaction conditions, such as flow rate, channel length, reaction temperature and feed policy, were investigated. It has been found that when the residence time is long enough, the molecular weight of the produced PPG is basically equal to the theoretical molecular weight. When the flow rate of initiator is fixed, an increase in flow rate of monomer will result in the molecular weight distribution (MWD) first widened and then narrowed. If the tube length is longer, the molecular weight is larger and the MWD is wider. If the temperature increases, the induction period of the polymerization can be shortened. Using the segmented feed, it is easier to prepare high molecular weight PPG with higher conversion than using the single feed, but the MWD is wider. These rules can be explained from the mechanism of PO ring-opening polymerization catalyzed by DMC and micro-mixing strength of materials in MCR. The lower the micro-mixing strength, and the smaller the rate ratio of chain transfer to chain propagation in polymerization, the wider the molecular weight distribution is.

Key words: microchannels, ring-opening polymerization, preparation, polypropylene glycol, high molecular weight, polymerization

中图分类号:

TQ 320.61

张雪婷, 胡激江, 赵晶, 李伯耿. 高分子量聚丙二醇在微通道反应器中的制备[J]. 化工学报, 2023, 74(3): 1343-1351.

Xueting ZHANG, Jijiang HU, Jing ZHAO, Bogeng LI. Preparation of high molecular weight polypropylene glycol in microchannel reactor[J]. CIESC Journal, 2023, 74(3): 1343-1351.

图/表 9

图1 DMC催化PO溶液聚合MCR装置示意图

Fig.1 The sketch map of MCR used for solution polymerization of PO catalyzed by DMC

表1 MCR中PO溶液聚合实验条件

Table 1 Experimental conditions for PO solution polymerization in MCR

Group^①	进料段数	反应温度/℃	MCR总管长/m	$Q n P P G$ ^②/(ml/min)
A	2	130	16	1.0
B	2	130	16	0.5
C	2	130	8	1.0
D	2	110	8	1.0
E	1	130	16	1.0

表1 MCR中PO溶液聚合实验条件

Table 1 Experimental conditions for PO solution polymerization in MCR

Group^①	进料段数	反应温度/℃	MCR总管长/m	$Q n P P G$ ^②/(ml/min)
A	2	130	16	1.0
B	2	130	16	0.5
C	2	130	8	1.0
D	2	110	8	1.0
E	1	130	16	1.0

图2 Group B中7个样品的转化率与数均分子量

Fig.2 The conversion and number-average molecular weight of samples produced by experiments in Group B

图3 不同nPPG流速(Group A和Group B)下聚合产物的数均分子量及多分散指数

Fig.3 Mn and Ð of PPGs produced in different nPPG feed rates (Group A and B)

图4 DMC催化的PO开环聚合的主反应

Fig.4 Main reactions in PO opening polymerization catalyzed by DMC

图5 不同微通道长度(Group A和Group C)时聚合产物的数均分子量和多分散指数

Fig.5 Mn and Ð of PPGs produced in different channel lengths (Group A and Group C)

图6 不同反应温度(Group C和Group D)下聚合产物的数均分子量和多分散指数

Fig.6 Mn and Ð of PPGs produced at different temperatures (Group C and Group D)

图7 不同进料方式(Group A和Group E)时聚合产物的数均分子量和多分散指数

Fig.7 Mn and Ð of PPGs produced with different feed policies (Group A and Group E)

图8 不同进料方式(Group A和Group E)时聚合产物的分子量分布曲线

Fig.8 Molecular weight distribution curves of PPGs produced with different feed policies (Group A and Group E)

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