Benzyl alcohol step pressure hydrolysis reaction process and system
阅读说明：本技术 一种苯甲醇梯级加压水解反应工艺及系统 (Benzyl alcohol step pressure hydrolysis reaction process and system ) 是由 刘广杰 贾永朋 杨勇 牛玉洁 李福成 周瑞兵 樊祥栋 王勤福 张英超 张永稳 渠 于 2019-11-08 设计创作，主要内容包括：本发明涉及一种苯甲醇梯级加压水解反应工艺及系统,氯化苄和纯碱溶液首先在塔式反应器、低压条件下进行快速反应,再在水解釜、常压条件下进一步降低反应物中氯化苄含量,得到苯甲醇粗品水解粗品再进行冷却、连续油水分离,油相经过减压粗馏、精馏得到产品。具有反应条件温和,反应时间短,二苄醚产出率低,设备材质要求低的生产特点,能降低项目建设成本和生产成本,解决了现有苯甲醇多釜串联常压水解生产工艺和高温高压连续水解反应工艺的不足。(The invention relates to a benzyl alcohol step pressure hydrolysis reaction process and a system, wherein benzyl chloride and sodium carbonate solution are firstly subjected to rapid reaction in a tower reactor under the condition of low pressure, then the content of benzyl chloride in a reactant is further reduced in a hydrolysis kettle under the condition of normal pressure, a benzyl alcohol crude product hydrolysis crude product is obtained, then cooling and continuous oil-water separation are carried out, and an oil phase is subjected to reduced pressure crude distillation and rectification to obtain a product. The method has the production characteristics of mild reaction conditions, short reaction time, low benzyl ether yield and low equipment material requirement, can reduce project construction cost and production cost, and solves the defects of the conventional benzyl alcohol multi-kettle series normal-pressure hydrolysis production process and high-temperature high-pressure continuous hydrolysis reaction process.)
1. A benzyl alcohol step pressure hydrolysis reaction process is characterized by comprising the following steps:
hydrolyzing part of benzyl chloride under pressure to form benzyl alcohol;
hydrolyzing the residual benzyl chloride under normal pressure to form benzyl alcohol.
2. The benzyl alcohol step pressure hydrolysis reaction process as claimed in claim 1, wherein the partial benzyl chloride is hydrolyzed under pressure at 120-150 ℃ and 0.2-0.5 MPa.
3. The benzyl alcohol step pressure hydrolysis reaction process as claimed in claim 1, wherein the temperature for hydrolyzing the residual benzyl chloride is 95-100 ℃ under normal pressure.
4. A benzyl alcohol step pressure hydrolysis reaction system is characterized by comprising: a preheater, a mixer, a pressurized tower reactor, a heater, a hydrolysis kettle and a condenser; the preheater, the mixer, the pressurized tower reactor, the hydrolysis kettle and the condenser are sequentially connected, and a liquid outlet at the bottom of the pressurized tower reactor is connected with a liquid inlet of the pressurized tower reactor.
5. The system of claim 4, wherein the preheater is disposed on the feed line of soda ash.
6. The system of claim 4, wherein the soda ash feed line is connected in parallel with the benzyl chloride feed line and both are connected to the mixer.
7. The system for the step pressure hydrolysis of benzyl alcohol as recited in claim 4, wherein the gas outlet at the top of the pressurized tower reactor is connected to the hydrolysis kettle.
8. The benzyl alcohol cascade pressure hydrolysis reaction system as claimed in claim 4, wherein the liquid inlet of the pressurized tower reactor is disposed at the top of the tower and at the middle of the tower, and a heater is disposed between the liquid inlet of the pressurized tower reactor and the liquid outlet at the bottom of the pressurized tower reactor.
9. The system for the step pressurized hydrolysis of benzyl alcohol according to claim 4, wherein a preheater is disposed between the liquid outlet at the bottom of the pressurized tower reactor and the hydrolysis kettle.
10. The system of claim 4, wherein the outlet of the condenser is connected to the inlet of the hydrolysis kettle.
Technical Field
The invention belongs to a benzyl alcohol step pressure hydrolysis reaction process technology, benzyl chloride and sodium carbonate solution are subjected to hydrolysis reaction in two combination modes of pressure and normal pressure to prepare benzyl alcohol, and the benzyl alcohol step pressure hydrolysis reaction process has the characteristics of high reaction rate, short reaction time, low byproduct rate, low equipment corrosion rate and the like.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
Benzyl alcohol is a colorless liquid, has aromatic flavor, is an important organic chemical raw material, and can be used as a solvent for preparing essence, a coating solvent, a photographic developer, a polyvinyl chloride stabilizer, a medicine synthesis, a synthetic resin solvent, a medicine injection solvent, an antiseptic of ointment or liquid medicine, meat product printing oil, ball-point pen oil and the like.
At present, the main production process of benzyl alcohol is a multi-kettle series normal pressure hydrolysis reaction process, and the process has the characteristics of long reaction time (8-10h), high side yield of benzyl ether, high energy consumption and large specification size of equipment; the continuous production process needs to be carried out under the conditions of high temperature and high pressure, and raw materials such as benzyl chloride, sodium carbonate and the like have high corrosion rate on equipment under the conditions of high temperature and high pressure and have high requirements on equipment materials.
Disclosure of Invention
In order to overcome the problems, the defects of the existing multi-kettle series normal pressure hydrolysis reaction process and the defect of high corrosion rate of the continuous pressurization reaction process to equipment are overcome, so that a high-efficiency and mild reaction condition process scheme is provided, the reaction rate is improved, the yield of the dibenzyl ether is reduced, and the material requirement of the equipment is reduced.
In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:
a benzyl alcohol step pressure hydrolysis reaction process comprises the following steps:
hydrolyzing part of benzyl chloride under certain pressure to form benzyl alcohol;
hydrolyzing the residual benzyl chloride under normal pressure to form benzyl alcohol.
The research of the invention finds that: the benzyl chloride and the sodium carbonate solution are subjected to hydrolysis reaction by combining pressurization and normal pressure to prepare the benzyl alcohol, and the method has the advantages of high reaction rate, short reaction time, low byproduct rate, low equipment corrosion rate and the like.
In some embodiments, the hydrolysis conditions of the partial benzyl chloride are 120-150 ℃ and 0.2-0.5 MPa under a certain pressure, and most of the benzyl chloride is hydrolyzed under the pressurized condition, so that the yield and the purity of the product are improved.
In some embodiments, the temperature for hydrolyzing the residual benzyl chloride is 95-100 ℃ under normal pressure, so that the unreacted residual benzyl chloride and a small amount of residual benzyl chloride are separated under the pressure in time, and the reaction is continued in the normal pressure reaction kettle.
The invention also provides a system for the pressure hydrolysis reaction of benzyl alcohol, which comprises: a preheater, a mixer, a pressurized tower reactor, a heater, a hydrolysis kettle and a condenser; the preheater, the mixer, the pressurized tower reactor, the hydrolysis kettle and the condenser are sequentially connected, and a liquid outlet at the bottom of the pressurized tower reactor is connected with a liquid inlet of the pressurized tower reactor.
The structural design realizes the combination of two reaction modes of pressurization and normal pressure, and after the reaction, the content of benzyl chloride in the hydrolyzed crude product can be reduced to 0.01 percent. The method can be carried out under mild conditions (120-150 ℃ and 0.2-0.5 MPa), reduces the corrosion degree of materials on equipment under a high-temperature and high-pressure state, reduces the reaction time and improves the reaction rate.
In some embodiments, the preheater is arranged on the feeding pipeline of the soda ash, and the subsequent hydrolysis reaction efficiency is improved by increasing the temperature of the alkali liquor during preheating.
The feeding pipeline of the soda ash is connected with the feeding pipeline of the benzyl chloride in parallel and is connected with the mixer, so that the preheated alkali liquor and the benzyl chloride are uniformly mixed in the mixer and then enter the subsequent pressurized tower reactor for hydrolysis reaction, and the reaction efficiency is improved.
In some embodiments, the exhaust port at the top of the pressurized tower reactor is connected with the hydrolysis kettle, so that carbon dioxide gas generated by the hydrolysis reaction is extracted from the top of the tower reactor to the normal-pressure hydrolysis kettle, and the pressure of the tower reactor is controlled by the extracted carbon dioxide.
In some embodiments, the liquid inlet of the pressurized tower reactor is arranged at the top of the tower and in the middle of the tower, and the heater is arranged between the liquid inlet of the pressurized tower reactor and the liquid outlet at the bottom of the pressurized tower reactor. And (3) decompressing a part of the hydrolysis crude product, then extracting the part of the hydrolysis crude product to a normal-pressure hydrolysis kettle, heating a part of the hydrolysis crude product to 120-150 ℃ by a heater, and then refluxing the part of the hydrolysis crude product to the tower reactor.
In the invention, the pressurized tower reactor only needs to be a tower reactor in the prior benzyl alcohol continuous production method.
In some embodiments, a preheater is arranged between the liquid outlet at the bottom of the pressurized tower reactor and the hydrolysis kettle to heat the materials, so that the reaction efficiency is improved.
In some embodiments, the liquid outlet of the condenser is connected with the liquid inlet of the hydrolysis kettle. Carbon dioxide gas and liquid phase flash steam are sent into a condenser through a riser in the normal pressure hydrolysis kettle, condensate liquid flows back to the normal pressure hydrolysis kettle, and the carbon dioxide gas is recycled.
The specific type and structure of the draft tube are not particularly limited in this application, and those skilled in the art can set the draft tube according to specific working conditions to achieve the purpose of feeding carbon dioxide gas and liquid phase flash steam from the hydrolysis kettle to the condenser.
The invention has the beneficial effects that:
(1) the invention adopts two reaction modes of pressurization and normal pressure to combine production, firstly, the pressurization operation is carried out to remove most of the raw material benzyl chloride, and the residual small amount of benzyl chloride is carried out in a normal pressure reaction kettle. After reaction, the content of benzyl chloride in the hydrolyzed crude product can be reduced to 0.01 percent. The method can be carried out under mild conditions (120-150 ℃ and 0.2-0.5 MPa), reduces the corrosion degree of materials on equipment under a high-temperature and high-pressure state, reduces the reaction time and improves the reaction rate.
(2) The invention provides a benzyl alcohol step pressure hydrolysis reaction process technology, which has the production characteristics of short reaction time, low benzyl ether output rate and small equipment corrosion rate, can reduce project construction cost and production cost, and solves the defects of the existing benzyl alcohol production process.
(3) The method has the advantages of simple operation method, low cost, universality and easy large-scale production.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a technical schematic diagram of a pressure hydrolysis reaction of benzyl alcohol in example 1.
Wherein, the system comprises 1, benzyl chloride 2, a benzyl
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As introduced in the background art, the reaction time for preparing the benzyl alcohol by the existing batch method is long (8-10h), and the side yield of the benzyl ether is high; the continuous method for preparing the benzyl alcohol has the problems of high temperature, high pressure and serious equipment corrosion. Therefore, the invention provides a benzyl alcohol step pressure hydrolysis reaction process technology, wherein benzyl chloride and soda solution are firstly subjected to rapid reaction in a tower reactor under the condition of low pressure, and then the content of benzyl chloride in a reactant is further reduced in a hydrolysis kettle under the condition of normal pressure, so that a benzyl alcohol crude product is obtained. The method comprises the following specific steps:
1. 10 to 12 percent of soda solution (mass fraction) is pressurized to 0.2 to 0.4MPa by a pump and preheated to 120 to 150 ℃ by a preheater.
2. And (3) the soda ash solution preheated by the preheater and benzyl chloride from a benzyl chloride delivery pump enter a pipeline mixer according to the mass ratio of 1: 4-6, and are fully mixed in the pipeline mixer.
3. And (3) feeding the mixed soda solution and benzyl chloride solution into a benzyl alcohol tower reactor, and carrying out hydrolysis reaction at the temperature of 120-150 ℃ and under the operation condition of 0.2-0.4 MPa.
4. In the
5. Carbon dioxide gas generated by the reaction is extracted from the tower top of the tower reactor to the normal-pressure hydrolysis kettle, and the pressure of the tower reactor is controlled by the extraction amount of the carbon dioxide.
6. Discharging liquid phase components such as a reactant sodium carbonate solution, benzyl chloride and benzyl alcohol generated by reaction from the bottom of the tower reactor, pressurizing by a pump, extracting a part of hydrolysis crude product to a normal-pressure hydrolysis kettle after reducing pressure, heating a part of hydrolysis crude product to 120-150 ℃ by a heater, and refluxing to the tower reactor, wherein the liquid level of the tower reactor is controlled by the extraction amount.
7. And 6, collecting the crude product of hydrolysis, wherein the content of benzyl chloride in the crude product of hydrolysis is less than or equal to 0.2%, cooling the crude product of hydrolysis by a preheater, feeding the crude product of hydrolysis into a normal-pressure hydrolysis kettle, continuously reacting at the normal pressure and at the temperature of 95-100 ℃, collecting the crude product of hydrolysis when the content of benzyl chloride in the kettle is reduced to 0.05%, cooling and continuously separating oil and water, and carrying out rough reduced-pressure distillation and rectification on an oil phase to obtain the product.
8. Carbon dioxide gas and liquid phase flash steam are sent into a condenser through a riser in the normal pressure hydrolysis kettle, condensate liquid flows back to the normal pressure hydrolysis kettle, and the carbon dioxide gas is recycled.
The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.
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