微反应器内甲苯连续二硝化制备二硝基甲苯

doi:10.11949/0438-1157.20240059

摘要/Abstract

摘要：

为实现二硝基甲苯（DNT）的安全高效生产，采用微反应技术，以甲苯为原料、硝硫混酸为硝化剂，研究了甲苯连续二硝化反应过程基本规律。提高反应温度、增加硝酸与甲苯的摩尔比、降低混酸含水量、减小硝硫摩尔比、集成釜式搅拌操作有利于DNT的生成；降低反应温度、提高混酸含水量和硝硫摩尔比，有利于降低2，4-/2，6-DNT比值。针对80/20DNT产品进行了硝化工艺优化。反应温度75℃，混酸含水量14%（质量分数），硝硫摩尔比1/4或1/3，搅拌时间5 min，产物中一硝基甲苯（MNT）含量小于0.2%，2，4-和2，6-DNT含量大于96%，2，4-/2，6-DNT比值小于4.25，其他DNT异构体含量均小于4%，符合行业标准。绝热条件下，室温进料，混酸含水量14%（质量分数），硝硫摩尔比1/4，搅拌时间10 min，产品质量符合行业标准。研究结果为甲苯连续二硝化工艺开发及80/20DNT产品的连续制备提供了基础。

关键词: 微反应器, 微通道, 过程强化, 硝化, 二硝基甲苯

Abstract:

In order to realize the safe and efficient production of dinitrotoluene (DNT), the behavior of toluene dinitration process was investigated by using microreaction technology with mixed acid as nitrating agent and toluene as raw material. Increasing the reaction temperature, elevating the molar ratio of nitric acid to toluene, reducing the water content of the mixed acid and decreasing N/S and integrating stirring were all conducive to the generation of DNT. Adjusting the isomer distribution of the product was achievable by reducing the reaction temperature, increasing the water content and N/S of the mixed acid, favorably reducing the 2,4-/2,6-DNT ratio. The process was optimized for 80/20DNT products. At a reaction temperature of 75^oC, a water content of mixed acid of 14%, N/S of 1/4 or 1/3, and a stirring time of 5 min, the product composition demonstrated desirable characteristics, i.e., the content of MNT in the product was less than 0.2%, 2,4-&2,6-DNT greater than 96% and other DNT less than 4%. More importantly, the ratio of 2,4-/2,6-DNT was less than 4.25. Under the conditions of adiabatic and room temperature feeding, a mixed acid water content of 14%, N/S of 1/4, and stirring time of 10 min, the product also complied with the industry standards. The study outcomes offer valuable technical insights for the continuous dinitration process of toluene and the continuous preparation of 80/20DNT products.

Key words: microreactor, microchannel, process intensification, nitration, dinitrotoluene

中图分类号:

TQ246.1

陈饶, 赵鑫, 陈戴欣, 姜圣坤, 廉应江, 王金波, 杨梅, 陈光文. 微反应器内甲苯连续二硝化制备二硝基甲苯[J]. 化工学报, DOI: 10.11949/0438-1157.20240059.

Rao CHEN, Xin ZHAO, Daixin CEHN, Shengkun JIANG, Yingjiang LIAN, Jinbo WANG, Mei YANG, Guangwen CHEN. Continuous dinitration of toluene to dinitrotoluene in a microreactor[J]. CIESC Journal, DOI: 10.11949/0438-1157.20240059.

图/表 11

参考文献 31

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Item	Quality index
Item	Premium grade	First-grade
appearance	no black impurities or suspended solids
2,4 + 2,6-DNT (%) ≥	95.0	95.0
2,4-DNT/2,6-DNT	3.76－4.26	3.65－4.41
2,5 + 3,5-DNT (%) ≤	1.0	1.0
2,3 + 3,4-DNT (%) ≤	4.0	4.5
MNT (%) ≤	0.2	0.2
TNT (%) ≤	0.1	0.1
nitrocresol (%) ≤	0.15	0.15

Item	Quality index
Item	Premium grade	First-grade
appearance	no black impurities or suspended solids
2,4 + 2,6-DNT (%) ≥	95.0	95.0
2,4-DNT/2,6-DNT	3.76－4.26	3.65－4.41
2,5 + 3,5-DNT (%) ≤	1.0	1.0
2,3 + 3,4-DNT (%) ≤	4.0	4.5
MNT (%) ≤	0.2	0.2
TNT (%) ≤	0.1	0.1
nitrocresol (%) ≤	0.15	0.15

φ/%	N/T	τ/min	t_stir/min	MNT/%	DNT/%	2,4-&2,6- DNT/%	2,4/2,6	other DNT/%
7	2.07	4.5	0	0.96	98.86	94.78	4.47	4.08
	2.18	4.4	0	0.10	99.74	95.59	4.50	4.14
	2.26	4.3	0	0.03	99.82	95.68	4.49	4.14
	2.07	4.5	5	0.10	99.73	95.57	4.49	4.16
	2.18	4.4	5	0.0	99.85	95.68	4.50	4.17
	2.26	4.3	5	0.0	99.83	95.67	4.50	4.17
10	2.05	4.3	0	9.83	90.15	86.89	4.27	3.26
	2.26	4.1	0	2.03	97.96	94.30	4.35	3.66
	2.05	4.3	5	6.71	93.26	89.89	4.26	3.38
	2.26	4.1	5	0.0	99.98	96.14	4.38	3.84
12	2.09	4.7	0	21.02	78.92	76.46	4.07	2.46
	2.17	4.5	0	16.68	83.31	80.60	4.12	2.71
	2.25	4.3	0	10.31	89.69	86.73	4.17	2.96
	2.09	4.7	5	7.76	92.02	89.08	4.11	2.94
	2.17	4.5	5	3.62	96.38	93.17	4.20	3.21
	2.25	4.3	5	1.31	98.69	95.31	4.26	3.38
14	2.08	4.5	0	38.66	61.33	59.52	3.95	1.81
	2.16	4.4	0	38.85	61.15	59.33	3.95	1.82
	2.26	4.3	0	34.80	65.20	63.23	3.97	1.96
	2.08	4.5	5	22.22	77.78	75.49	3.90	2.29
	2.16	4.4	5	19.14	80.86	78.45	3.92	2.40
	2.26	4.3	5	15.25	84.75	82.15	4.01	2.60

φ/%	N/T	τ/min	t_stir/min	MNT/%	DNT/%	2,4-&2,6- DNT/%	2,4/2,6	other DNT/%
7	2.07	4.5	0	0.96	98.86	94.78	4.47	4.08
	2.18	4.4	0	0.10	99.74	95.59	4.50	4.14
	2.26	4.3	0	0.03	99.82	95.68	4.49	4.14
	2.07	4.5	5	0.10	99.73	95.57	4.49	4.16
	2.18	4.4	5	0.0	99.85	95.68	4.50	4.17
	2.26	4.3	5	0.0	99.83	95.67	4.50	4.17
10	2.05	4.3	0	9.83	90.15	86.89	4.27	3.26
	2.26	4.1	0	2.03	97.96	94.30	4.35	3.66
	2.05	4.3	5	6.71	93.26	89.89	4.26	3.38
	2.26	4.1	5	0.0	99.98	96.14	4.38	3.84
12	2.09	4.7	0	21.02	78.92	76.46	4.07	2.46
	2.17	4.5	0	16.68	83.31	80.60	4.12	2.71
	2.25	4.3	0	10.31	89.69	86.73	4.17	2.96
	2.09	4.7	5	7.76	92.02	89.08	4.11	2.94
	2.17	4.5	5	3.62	96.38	93.17	4.20	3.21
	2.25	4.3	5	1.31	98.69	95.31	4.26	3.38
14	2.08	4.5	0	38.66	61.33	59.52	3.95	1.81
	2.16	4.4	0	38.85	61.15	59.33	3.95	1.82
	2.26	4.3	0	34.80	65.20	63.23	3.97	1.96
	2.08	4.5	5	22.22	77.78	75.49	3.90	2.29
	2.16	4.4	5	19.14	80.86	78.45	3.92	2.40
	2.26	4.3	5	15.25	84.75	82.15	4.01	2.60

N/S	N/T	τ/min	t_stir/min	MNT/%	DNT/%	2,4-&2,6- DNT/%	2,4/2,6	other DNT/%
1:3	2.05	4.8	0	14.96	85.03	82.22	4.13	2.81
	2.17	4.6	0	11.99	88.01	85.06	4.17	2.95
	2.23	4.5	0	8.86	91.14	88.03	4.17	3.11
	2.05	4.8	5	1.42	98.58	95.17	4.22	3.42
	2.17	4.6	5	0.68	99.31	95.79	4.23	3.52
	2.23	4.5	5	0.19	99.79	96.25	4.25	3.55
1:4	2.05	4.9	0	8.50	91.47	88.56	4.26	2.92
	2.17	4.7	0	5.64	94.35	91.16	4.22	3.19
	2.23	4.5	0	2.57	97.41	93.94	4.19	3.47
	2.05	4.9	5	2.56	97.42	94.12	4.21	3.30
	2.17	4.7	5	0.05	99.93	96.29	4.20	3.65
	2.23	4.5	5	0.0	99.99	96.43	4.25	3.57