阅读说明：本技术 一种利用微通道反应器无碱制备苯甲醇的方法 (Method for preparing benzyl alcohol by using microchannel reactor without alkali ) 是由 周峰 黄正望 孙波 李毅 袁鹏 李显文 方磊 熊东 陈凯 张龙基 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种利用微通道反应器无碱制备苯甲醇的方法,本发明将氯化苄和水按一定比例加入预热加压的微通道反应器中进行连续水解反应,反应后的混合物经冷却降温、沉降分层后,分离出油相和水相,油相经过脱轻塔和成品塔两级减压精馏制备工业级苯甲醇。本发明无需碱参与氯化苄的水解,不会产生氯化钠废水,降低成本,并且在精馏时也不会造成物料的分解；采用微通道反应器来进行水解反应,减少了反应的时间和空间,提高了水解的效率。本发明方法具有流程简单,节约原料、减少副产物,降低成本等优点,而且采用本发明制备的苯甲醇含量达到工业级苯甲醇标准,经济效益得到提高。(The invention discloses a method for preparing benzyl alcohol without alkali by using a microchannel reactor. The method does not need alkali to participate in the hydrolysis of the benzyl chloride, does not generate sodium chloride waste water, reduces the cost, and does not cause the decomposition of materials during rectification; the micro-channel reactor is adopted for hydrolysis reaction, so that the reaction time and space are reduced, and the hydrolysis efficiency is improved. The method has the advantages of simple process, raw material saving, byproduct reduction, cost reduction and the like, and the content of the benzyl alcohol prepared by the method reaches the industrial-grade benzyl alcohol standard, so that the economic benefit is improved.)

1. A method for preparing benzyl alcohol by using a microchannel reactor without alkali is characterized by comprising the following steps:

firstly, integrally preheating a microchannel reactor, and simultaneously pressurizing the microchannel reactor by using inert gas;

step two, continuously pumping the benzyl chloride A and the water B into a preheated microchannel reactor respectively for reaction to obtain a mixed material after the reaction is finished;

step three, cooling, settling and layering the mixed material obtained in the step two to respectively obtain a water phase C and an oil phase D;

step four, enabling the water phase C obtained in the step three to pass through an adsorption resin column, then carrying out steam analysis on the adsorption resin, settling and layering analyzed materials to respectively obtain a water phase F and an oil phase G, and mixing the oil phase G and the oil phase D to form an oil phase mixture H;

step five, continuously feeding the oil phase mixture H obtained in the step four from the middle part of the light component removal tower, condensing and discharging at the top of the light component removal tower to obtain benzyl chloride M, and discharging at the bottom of the light component removal tower to obtain an oil phase I;

and step six, continuously feeding the oil phase I obtained in the step five from the middle part of a finished product tower, condensing and discharging at the top of the finished product tower to obtain a benzyl alcohol finished product J, and discharging at the bottom of the finished product tower to obtain a high-boiling-point substance K.

2. The alkali-free preparation method of benzyl alcohol by using the microchannel reactor as claimed in claim 1, wherein: in the first step, the preheating temperature of the microchannel reactor is 140-.

3. The alkali-free preparation method of benzyl alcohol by using the microchannel reactor as claimed in claim 1, wherein: in the second step, the mass ratio of the benzyl chloride A and the water B pumped into the microchannel reactor is 1: (4-5), the flow rate of the benzyl chloride A is 2-3kg/min, the flow rate of the water B is 9-15kg/min, and the reaction residence time is 4.1-6.7 min.

4. The alkali-free preparation method of benzyl alcohol by using the microchannel reactor as claimed in claim 1, wherein: in the third step, the cooling temperature is 36-44 ℃.

5. The alkali-free preparation method of benzyl alcohol by using the microchannel reactor as claimed in claim 1, wherein: in the fourth step, the steam pressure of the steam desorption is 0.3-0.6 MPa.

6. The method for preparing benzyl alcohol without alkali by using the microchannel reactor as claimed in claim 5, wherein: in the fourth step, the steam pressure of the steam desorption is 0.45 MPa.

7. The method for preparing benzyl alcohol without alkali by using the microchannel reactor as claimed in claim 5, wherein: in the fourth step, the water phase F accounts for 50-60% and the oil phase G accounts for 40-50% by mass percentage.

8. The alkali-free preparation method of benzyl alcohol by using the microchannel reactor as claimed in claim 1, wherein: in the fifth step, the rectification pressure of the light component removal tower is 3.5-6.7kPa, the tower top temperature is 82-103 ℃, and the tower bottom temperature is 115-129 ℃.

9. The alkali-free preparation method of benzyl alcohol by using the microchannel reactor as claimed in claim 1, wherein: in the sixth step, the distillation pressure of the finished product tower is 1-4kPa, the tower top temperature is 81-118 ℃, and the tower bottom temperature is 137-167 ℃.

Technical Field

The invention relates to the field of production of benzyl alcohol in synthetic chemical industry, in particular to a method for preparing benzyl alcohol by using a microchannel reactor without alkali.

Background

The benzyl alcohol is the simplest aliphatic alcohol containing phenyl, is colorless transparent viscous liquid with weak aromatic odor, has the characteristics of polarity, low toxicity and low vapor pressure, is widely used as a solvent in daily chemicals, coatings and polymer industries, and has the characteristics of environmental protection, no toxicity and good solubility.

The main process for preparing benzyl alcohol at present comprises the following steps: the benzyl chloride is used as a raw material, is heated and hydrolyzed under the action of alkali, and is subjected to working procedures of settling fractionation and the like to obtain industrial-grade benzyl alcohol. The separation and purification of the benzyl alcohol mostly adopts a reduced pressure distillation method, in the process of reduced pressure distillation, inorganic components such as sodium chloride and sodium carbonate are separated out in the distillation process due to the fact that the water contains the inorganic components such as the sodium chloride and the like, the separated salts can block the filler of a pipeline and a tower, the materials can be decomposed at high temperature, the continuous production is not facilitated, in addition, the use cost of alkali and the treatment cost of salt-containing wastewater are very high, and the production cost of the benzyl alcohol is increased in both aspects. Meanwhile, benzyl alcohol can also generate 10 to 25 percent of dibenzyl ether and other byproducts in the alkaline hydrolysis reaction, so the economic value is low and the application range is not wide. Therefore, a new process for preparing benzyl alcohol by alkali-free hydrolysis of benzyl chloride is urgently needed to be developed.

Microchannel reactors are three-dimensional structural elements that can be used to carry out chemical reactions that are fabricated in a solid matrix by means of special microfabrication techniques. Microchannel reactors typically contain small channel sizes (equivalent diameters less than 500 μm) and channel diversity in which the fluid flows and in which the desired reactions are required to occur. This results in a very large surface area to volume ratio in a micro-structured chemical device.

The micro-channel reactor equipment has extremely large specific surface area due to the internal microstructure, which can reach hundreds of times or even thousands of times of the specific surface area of the stirring kettle. The microchannel reactor has excellent heat transfer and mass transfer capacity, can realize instantaneous uniform mixing of materials and high-efficiency heat transfer, so that a plurality of reactions which cannot be realized in the conventional reactor can be realized in the microchannel reactor. At present, microchannel reactors are widely applied to research and development of chemical process, and are increasingly applied to commercial production, and the main application fields of the microchannel reactors include organic synthesis process, preparation of micron and nanometer materials and production of daily chemicals.

Disclosure of Invention

In view of the above, the invention provides a method for preparing benzyl alcohol without alkali by using a microchannel reactor, which is used for solving the current situation that a large amount of alkali is needed to be used and a large amount of salt-containing wastewater is generated in the current benzyl alcohol preparation process, reducing the proportion of dibenzyl ether as a byproduct, eliminating other solvents and reagents except benzyl chloride and water in the whole process, improving the yield of benzyl alcohol and reducing the production cost.

The technical scheme of the invention is realized as follows: the invention provides a method for preparing benzyl alcohol by using a microchannel reactor without alkali, which comprises the following steps:

firstly, integrally preheating a microchannel reactor, and simultaneously pressurizing the microchannel reactor by using inert gas;

step two, continuously pumping the benzyl chloride A and the water B into a preheated microchannel reactor respectively for reaction to obtain a mixed material after the reaction is finished;

step three, cooling, settling and layering the mixed material obtained in the step two to respectively obtain a water phase C and an oil phase D;

step four, enabling the water phase C obtained in the step three to pass through an adsorption resin column, then carrying out steam analysis on the adsorption resin, settling and layering analyzed materials to respectively obtain a water phase F and an oil phase G, and mixing the oil phase G and the oil phase D to form an oil phase mixture H;

step five, continuously feeding the oil phase mixture H obtained in the step four from the middle part of a light component removal tower, condensing and discharging at the top of the light component removal tower to obtain benzyl chloride M, discharging at the bottom of the light component removal tower to obtain an oil phase I, wherein the oil phase I comprises benzyl alcohol, high-boiling residues and the like;

and step six, continuously feeding the oil phase I obtained in the step five from the middle part of a finished product tower, condensing and discharging at the top of the finished product tower to obtain a benzyl alcohol finished product J, and discharging at the bottom of the finished product tower to obtain a high-boiling-point substance K.

In addition to the above technical solutions, preferably, the water B is raw water or the recovered water phase F is mixed with raw water.

On the basis of the technical scheme, preferably, the benzyl chloride a is a mixture of a raw material benzyl chloride or recovered benzyl chloride M and the raw material benzyl chloride.

On the basis of the technical scheme, the temperature of the microchannel reactor in the step one is 140-.

On the basis of the technical scheme, in the second step, the mass ratio of the benzyl chloride A to the water B pumped into the microchannel reactor is 1 (4-5), the flow rate of the benzyl chloride A is 2-3kg/min, the flow rate of the water B is 9-15kg/min, and the reaction residence time is 4.1-6.7 min.

On the basis of the technical scheme, in the third step, the cooling temperature is 36-44 ℃.

On the basis of the technical scheme, in the step four, the water phase C is subjected to removal of benzyl alcohol and benzyl chloride through an adsorption resin column, and then is used for absorbing toluene chlorination tail gas to prepare high-concentration industrial hydrochloric acid E; after the resin is saturated by adsorbing benzyl alcohol and benzyl chloride, steam analysis is carried out by using the steam pressure of 0.3-0.6MPa, and the analyzed resin can be reused.

Further, in the fourth step, the steam pressure resolved by the steam is 0.45 MPa.

Further, in the fourth step, according to the mass percentage, the water phase F obtained after sedimentation and demixing accounts for 50-60%, and the oil phase G accounts for 40-50%.

On the basis of the technical scheme, in the fifth step, the rectifying pressure of the light component removal tower is 3.5-6.7kPa, the tower top temperature is 82-103 ℃, and the tower bottom temperature is 115-129 ℃.

On the basis of the technical scheme, in the sixth step, the rectification pressure of the finished product tower is 1-4kPa, the tower top temperature is 81-118 ℃, and the tower bottom temperature is 137-167 ℃.

The invention adds benzyl chloride and water into a preheated and pressurized microchannel reactor according to a certain proportion for hydrolysis reaction, and after the mixture after the reaction is cooled, settled and layered, an oil phase and a water phase (containing benzyl alcohol and hydrochloric acid) are separated. The water phase is used for absorbing tail gas generated in toluene chlorination after removing benzyl alcohol and a small amount of benzyl chloride through an adsorption resin column, the oil phase is used for preparing industrial benzyl alcohol through two-stage vacuum rectification of a light removal tower and a finished product tower, and unreacted benzyl chloride recovered from the light removal tower and the water phase resolved by a small amount of resin return to the microchannel reactor again to participate in hydrolysis reaction again.

Compared with the prior art, the method for preparing benzyl alcohol by using the microchannel reactor without alkali has the following beneficial effects:

1. the method avoids using alkali to participate in the hydrolysis of benzyl chloride, does not generate a large amount of sodium chloride wastewater, and reduces the use cost of the alkali and the treatment cost of the salt-containing wastewater. Meanwhile, in the process of reduced pressure distillation, the oil phase does not contain inorganic components such as sodium chloride, sodium carbonate and the like, so that the inorganic components such as sodium chloride and the like are not separated out to block the pipeline and the filler of the tower, the material is not decomposed at high temperature, the service cycle of the rectifying tower is prolonged, and the continuous production is facilitated.

2. The hydrolysis reaction is carried out by adopting the microchannel reactor, compared with the traditional stirred tank, the mass transfer effect and the heat transfer effect of the microchannel reactor are very high, the benzyl chloride and the water can be fully mixed instantly, the mixed phase can reach the temperature required by the reaction instantly, the reaction time is greatly shortened, and the proportion of the generated side product dibenzyl ether is reduced. Meanwhile, the micro-channel reactor adopted by the invention achieves the mixing effect by the turbulence among materials, does not need moving equipment such as a stirring paddle, and has the advantages of less equipment investment, small occupied area, difficult damage and long service cycle.

3. The method adopts a continuous feeding and discharging mode to carry out reaction, can really realize the continuous production of the benzyl alcohol, only needs resources such as benzyl chloride, water, low-pressure steam and the like, does not need other solvents and reagents, can recycle the adsorption resin for treating the oil-containing water phase, has simple whole process flow, improves the yield of the benzyl alcohol, reduces the production cost, and is economical and practical.

Therefore, compared with the traditional benzyl chloride alkaline hydrolysis method for preparing the benzyl alcohol, the production method has the advantages of simple flow, raw material saving, byproduct reduction, cost reduction and the like, and the content of the benzyl alcohol prepared by the method reaches the industrial-grade benzyl alcohol standard, so that the economic benefit is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart of the process for preparing benzyl alcohol without alkali by using a microchannel reactor according to the present invention.

Detailed Description

The technical solution of the present invention will be described clearly and completely with reference to fig. 1 and the detailed description of the invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the following examples,% is by mass unless otherwise specified.