CN1037340C

CN1037340C - Method and equipment for producing benzyl fluoride

Info

Publication number: CN1037340C
Application number: CN94114036A
Authority: CN
Inventors: 杨政; 俞迪虎; 俞祖勋
Original assignee: FINE CHEMICAL PLANT ZHEJIANG UNIV
Current assignee: FINE CHEMICAL PLANT ZHEJIANG UNIV
Priority date: 1994-12-13
Filing date: 1994-12-13
Publication date: 1998-02-11
Anticipated expiration: 2014-12-13
Also published as: CN1110270A

Abstract

The present invention relates to a manufacturing method and a device for benzyl chloride. Toluene and chlorine gas are used as raw materials, the manufacturing method is characterized in that an adopted catalyst is any one of azodiisobutyronitrile, tert-butyl hydroperoxide benzoyl peroxide and dicumyl peroxide, the addition amount of the adopted catalyst is from 0.05 to 0.5 wt%, the reaction temperature is from 75 to 90 DEG C, the induction time is 10 minutes, a reactor 1 adopts a circulating current reactor, and a condenser 9 is arranged on the upper part of the reactor 1. Compared with the prior art, the present invention has the advantages that the technology performance indexes, such as the purity, the color degree, the deposition period, etc. of a product are superior to the existing products, the single-pass conversion rate of the toluene is increased to 50 to 60% from 30%, the chlorine consumption for producing the benzyl chloride per ton is reduced to 0.56 to 0.6 ton from 0.76 ton, the reaction temperature is reduced to 75 to 90 DEG C from 120 to 125 DEG C, and the rectification energy consumption is saved by 30 to 60%.

Description

Benzyl chloride production method and equipment

The invention relates to a halogenation reaction for forming chlorine-containing organic compounds, in particular to a method and equipment for producing benzyl chloride.

Benzyl chloride is an important organic chemical intermediate and is used for manufacturing phenylacetic acid, benzyl alcohol, benzyl phthalate, benzyl cyanide, benzyl ester products, quaternary ammonium salt, pesticide, disinfectant products and the like.

The common production method of benzyl chloride is a photochlorination method, wherein methylbenzene and chlorine are used as raw materials, an ultraviolet irradiator and a stirrer are arranged in a conventional reactor, the reaction is carried out under the conditions of photocatalysis, stirring and a temperature of 120-125 ℃, the chemical reaction is a side chain free radical chain reaction, and the reaction formula is as follows:

the reaction product is rectified and condensed under reduced pressure to obtain a benzyl chloride product, and the intermediate fraction and the toluene are recycled. The gas generated by the reaction is absorbed by the HCl absorption tower and the oxygen absorption tower and then is discharged.

The equipment for producing benzyl chloride by a photochlorination method is shown in figure 1 and comprises a reactor 1, a rectifying tower 2, a partial condenser 3, a complete condenser 4, a benzyl chloride storage tank 5, a middle distillate tank 6, a toluene storage tank 7, a hydrogen chloride absorption tower 8, a chlorine absorption tower 8 ', a pipeline and valves K1-K7, wherein an ultraviolet light irradiator 1l and a stirrer 12 are arranged in the reactor 1, a feed inlet A is arranged at the upper part of the reactor, the pressure of chlorine is 0.12MPa, the chlorine is introduced from a gas inlet B arranged at the lower part of the reactor, the reaction is carried out at the temperature of 120-125 ℃, gas generated by the reaction is sent to the HCl absorption tower 8 and the chlorine absorption tower 8' for treatment through the pipeline, reaction products are sent to the rectifying tower 2 through the pipeline, fractions are condensed through the partial condenser 3 and the complete condenser 4, and are respectively sent to the benzyl chloride storage tank 6 and the toluene storage tank 7 through the valve K2. The middle distillate and toluene in the tank are respectively sent to the rectifying tower 2 and the reactor 1 for use, and the residue in the rectifying tower 2 is discharged from a bottom valve K1.

The prior art has the following defects:

1. the reaction temperature is high and needs 120-125 ℃, and the reaction depth is not easy to control;

2. the consumption of raw materials is large, and the chlorine consumption of each ton of products is 0.76 ton;

3. the benzyl chloride product has low purity of 96-98%;

4. the conversion per pass of the toluene is below 30 percent, so the rectification energy consumption is large, the chlorine content of reaction tail gas is about 3 (V)%, and the reaction tail gas can be discharged after dechlorination treatment;

5. the product has poor chemical stability, and obviously becomes turbid when the storage period is less than 5 months.

The invention aims to provide a benzyl chloride production method and equipment, wherein a circulation reactor is adopted, so that chlorine and toluene can be fully contacted in the circulation process, the reaction effect is improved, a proper catalyst is selected, the reaction temperature is reduced from 120-125 ℃ to 75-90 ℃, the technical indexes of the produced benzyl chloride product such as purity, chromaticity, stable storage time and the like are obviously improved, and the chlorine consumption and the energy consumption of each ton of the produced benzyl chloride product are greatly reduced.

The technical key point for realizing the aim of the invention is to design a reactor capable of ensuring the full reaction of chlorine and toluene, the circulating reactor is particularly suitable for the production of benzyl chloride, the reaction temperature can be reduced by adopting a proper catalyst, the induction period is 10 minutes, and the chlorine absorption effect is good.

Fig. 1 is a schematic structural diagram of a conventional benzyl chloride production apparatus.

FIG. 2 is a schematic structural diagram of the benzyl chloride production equipment of the present invention.

The method and the special equipment designed for implementing the method are described in detail in the following with reference to the attached drawings.

A production method of benzyl chloride is characterized in that methylbenzene and chlorine are used asraw materials, after catalytic reaction, the reaction product is rectified and condensed to obtain a benzyl chloride product, middle distillate and methylbenzene are collected for reuse, and gas generated by the reaction is sent to a hydrogen chloride absorption tower for treatment.

The special equipment for implementing the method comprises a reactor 1, a rectifying tower 2, a partial condenser 3, a full condenser 4, a benzyl chloride storage tank 5, a middle distillate tank 6, a toluene storage tank 7, a hydrogen chloride absorption tower 8, connecting pipelines and valves K1-K7, and is characterized in that the reactor 1 adopts a loop reactor, the exterior of the loop reactor is provided with a jacket 13, the lower part of the jacket is provided with a water inlet C and a condensed water outlet F, and the upper part of the jacket is provided with a water outlet D and a steam inlet E; the upper part of the reactor 1 is provided with a condenser 9. The reaction temperature was measured by a thermometer T, A being a charging port and B being a chlorine inlet.

Compared with the prior art, the invention has the following advantages:

1. the product quality is obviously improved, the purity is improved from 96-98% to 99%, the appearance is colorless and transparent, and the stable storage time is not less than 7 months. The prior product is brownish red or yellow in appearance and begins to become turbid after being stored for 5 months;

2. the chlorine consumption of each ton of benzyl chloride products is reduced from 0.76 ton to below 0.6 ton, and the tail gas does not contain chlorine;

3. the single-pass conversion rate of the toluene is improved from 30 percent to more than 50 percent, and the energy consumption of rectification is saved by 30 to 60 percent;

4. the reaction temperature is low and is reduced from 120-125 ℃ to 75-90 ℃.

Example 1:

a benzyl chloride production facility as shown in figure 2, the reactor is made of enamel steel pipe, the inner diameter of the reactor is 200mm, the height of the reaction section is 6 m, the rectifying still is 2000 liter enamel still, the tower diameter of the rectifying tower is 400mm, the height of the tower is 8 m, the rectangular saddle packing, the enamel lining, the partial condenser and the total condenser are all enamel lining.

The reaction conditions for producing benzyl chloride are as follows:

the system is vacuumized by a water jet pump, the vacuum degree is 0.092MPa, and the air extraction amount is 40 cubic meters per hour;

chlorine gas: toluene at a MOL ratio of 0.5

The catalyst adopts azobisisobutyronitrile, and the addition amount of the azodiisobutyronitrile is 0.1 wt% of the raw material;

the reaction temperature is 85 ℃;

the chlorine passage time was 1.5 hours.

The yield of benzyl chloride is 200 tons, the conversion rate of toluene is 55%, the selectivity is 98% and the chlorine absorption rate is 100%. Each ton of benzyl chloride product consumes 0.73 ton of toluene, and each ton of chlorine gas is 0.57 ton, and the product is colorless. And (3) testing results: the purity of benzyl chloride is 99%, and the benzyl chloride does not deteriorate after being stored for 7 months and has no turbidity.

Example 2:

by applying the equipment of the invention, the catalyst adopts tert-butyl hydroperoxide, the addition amount of the tert-butyl hydroperoxide is 0.05 wt% of the raw material, the reaction temperature is 90 ℃, other processconditions and the product quality are the same as those of the example 1, the conversion rate of the obtained toluene is 58%, and the selectivity is 99%.

Example 3:

by applying the equipment of the invention, the catalyst adopts benzoyl peroxide, the adding amount of the benzoyl peroxide is 0.15 wt% of the raw material, the reaction temperature is 80 ℃, other process conditions and the product quality are the same as those of the example 1, the conversion rate of the obtained toluene is 53%, and the selectivity is 98%.

Example 4:

by applying the equipment of the invention, the catalyst adopts dicumyl peroxide, the addition amount of the dicumyl peroxide is 0.2wt% of the raw material, the reaction temperature is 75 ℃, other process conditions and the product quality are the same as those of the example 1, the conversion rate of the obtained toluene is 54%, and the selectivity is 99%.

Claims

1. A method for producing benzyl chloride uses methylbenzene and chlorine as raw materials, and comprises the steps of carrying out catalytic reaction, rectifying and condensing a crude product of the reaction to obtain a benzyl chloride product, collecting intermediate fraction and methylbenzene for reuse, and sending gas generated by the reaction to a hydrogen chloride absorption tower for treatment, wherein the method comprises the following steps: the reaction for producing benzyl chloride is carried out in a loop reactor, the catalyst is any one of azodiisobutyronitrile, tert-butyl hydroperoxide, benzoyl peroxide and dicumyl peroxide, the addition amount of the catalyst is 0.05-0.2 wt%, the reaction temperature is 75-90 ℃, and the induction time is 10 minutes.

2. Aspecial apparatus for carrying out the process according to claim 1, comprising a reactor [1], a rectifying column [2], a partial condenser [3], a total condenser [4], a benzyl chloride storage tank [5], a middle distillate tank [6], a toluene storage tank [7], a hydrogen chloride absorption column [8]and connecting pipes and valves [ K1]to [ K8], wherein: the reactor [1]adopts a circulation type reactor, a jacket [13]is arranged outside the reactor, a water inlet [ C]and a condensed water outlet [ F]are arranged at the lower part of the jacket, a water outlet [ D]and a steam inlet [ E]are arranged at the upper part of the jacket, and a condenser [9]is arranged at the upper part of the reactor [1].