Nitration method for synthesizing dinitrotoluene in one step, and microchannel reactor

A technology of microchannel reactor and dinitrotoluene, which is applied in the preparation of nitro compounds, chemical instruments and methods, organic chemistry, etc., can solve the problems of high production cost, long reaction time, unsafety, etc., and achieve material saving Cost, process safety and continuity, and the effect of increasing space-time productivity

Active Publication Date: 2009-09-30
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] From the point of view of the single-pass conversion rate and product selectivity of the reactor, its production cost of the method for the synthesis of dinitrotoluene described in the above disclosed patents is all expensive, because there are many reactor stages (called cascade reaction) device), the ratio of raw materials is s

Method used

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  • Nitration method for synthesizing dinitrotoluene in one step, and microchannel reactor
  • Nitration method for synthesizing dinitrotoluene in one step, and microchannel reactor
  • Nitration method for synthesizing dinitrotoluene in one step, and microchannel reactor

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Embodiment 1

[0062] Use anhydrous nitric acid (≥98%) and concentrated sulfuric acid (>95%) to prepare a mixed acid with a molar ratio of nitric acid and sulfuric acid of 0.3 and a water concentration of 2.87%. During the preparation of mixed acid, the temperature can be controlled below 35°C. Under normal temperature conditions, the mixed acid and toluene were continuously pumped into the microreactor ( figure 2 The reactor shown) and react in the micro reaction channel. Control the molar ratio of nitric acid and toluene to 2.0, and the liquid hourly space velocity of the reactor is 600~2000h -1 . The reaction product flows out of the reactor continuously, and is statically layered in the separator to separate the acid solution, and the organic phase is washed with water, alkali and water until neutral. The reaction result is attached image 3 . image 3 The result shows that under the microchannel reactor used in this implementation and reaction condition, improving space velocity i...

Embodiment 2

[0064]The process and the reactor used are the same as in Example 1, the molar ratio of nitric acid to sulfuric acid is changed to 0.5, the molar ratio of nitric acid to toluene is 2.15, the reactor is operated at normal temperature, and the liquid hourly space velocity in the reactor is 500~2000h -1 . The implementation results are attached Figure 4 Show. Compared with Example 1, the concentration of nitric acid increases, the selectivity of DNT decreases by 11-17%, the selectivity of MNT increases, and the conversion rate of toluene remains unchanged.

Embodiment 3

[0066] Process is with embodiment 1, and reactor uses attached figure 1 In the 'T'-shaped single-channel structure microreactor shown in , the molar ratio of nitric acid and sulfuric acid is 1.0, the mass concentration of water in the mixed acid is 2.87%, the molar ratio of nitric acid and toluene is 2.45, and the reaction is carried out at a space velocity of 4000-50000h -1 within. The implementation results are attached Figure 5 , the degree of toluene nitration conversion in the microreactor is almost not limited by the space velocity, the reaction residence time has little effect on the nitration conversion, and the toluene conversion rate is at a space velocity of 52870h -1 conditions can still be as high as 97.5% at 40000h -1 In a wide range of space velocity, the selectivity of main product DNT increased obviously, while the selectivity of MNT decreased. The ratio of the two major isomers of DNT, 2,4-DNT to 2,6-DNT, hardly changed in the wide space velocity range, b...

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Abstract

The invention relates to one-step dinitrotoluene synthesis in a microchannel reactor. The method comprises the steps of taking toluene and mixed acid of nitric acid/sulfuric acid (n/s) as initial reaction materials, inputting material flow synchronously into a microreactor through a metering pump and finishing mixed mass transfer and reaction in a reaction channel. The substance ratio of n to s in the reactive mixed acid is 0.1 to 1.0, and the mass ratio of water is less than 15 percent. The liquid hourly space velocity in the reactor is 500 to 50,000 h<-1>. The microchannel reactor adopts a stainless steel flat-plate structure which comprises fixed pressing-sealing plates, a microchannel plate, a raw-material inlet, a product outlet, as well as a temperature-control pore channel and a thermal-couple measurement-control jack which are positioned on two sealing plates. The method is continuously operated under a technological condition with medium/strong nitrating acid, and is safe in process. The conversion rate of the toluene in the reactor at an operation temperature between normal temperature and 80 DEG C is higher than 98 percent, and the yield of dinitrotoluene is higher than 95 percent, wherein the ratio of two main isomer components, namely 2,4-dinitrotoluene and 2,6-dinitrotoluene, is more than 4 and can be nearly 5 under optimum conditions.

Description

technical field [0001] The present invention relates to the nitration of aromatic hydrocarbons, specifically a nitration method and a microchannel reactor for synthesizing dinitrotoluene in one step, wherein dinitrotoluene is synthesized in one step from toluene in the microchannel reactor; The safe and continuous synthesis of dinitrotoluene in a microchannel reactor under the reactor condition of up to 80°C, wherein the design and application of the microchannel reactor belongs to the field of new chemical reactors. Background technique [0002] Toluene nitration is an important reaction in the chemical industry, and its nitrated product dinitrotoluene (DNT) is mainly used in the preparation of dyes, paints, and coatings, and is also a precursor for the production of explosives and toluene diisocyanate (TDI). Conventional industrial production DNT method is to use many ring-type or multi-pot-type stirring reaction systems connected in series or in parallel to make toluene a...

Claims

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Application Information

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IPC IPC(8): C07C205/06C07C201/08B01J19/00
CPCY02P20/141
Inventor 陈光文焦凤军赵玉潮袁权
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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