Method and device for improving selectivity and yield of benzyl alcohol industrial production reaction

Abstract

The invention relates to the technical field of benzyl alcohol industrial production, and provides a method and device for improving reaction selectivity and yield of benzyl alcohol industrial production, and the method comprises the following steps: S1, mixing benzyl chloride and an alkali solution, and injecting the mixture into a hydrolysis reaction kettle for hydrolysis reaction; s2, cooling after the reaction is finished, adding a NaCl solution, uniformly mixing, and separating in an oil-water separator to obtain an oil-phase material and a water-phase material; s3, the oil-phase material enters a rectifying tower to be rectified, and benzyl alcohol is obtained. The oil / water phase separation needs a certain density difference, the density of the water phase is improved by supplementing the NaCl solution into the reaction liquid, so that the oil / water phase entering the settling process can be thoroughly layered, the thorough separation of the oil / water phase is ensured, and the reaction selectivity and the yield of benzyl alcohol are further improved.

Description

Technical Field

[0001] The invention relates to the technical field of industrial production of benzyl alcohol, and in particular to a method and a device for improving the reaction selectivity and yield of industrial production of benzyl alcohol. Background Art

[0002] Benzyl alcohol, also known as benzyl alcohol, is a colorless, transparent, viscous liquid with the characteristics of polarity, low toxicity, and low vapor pressure. Therefore, it is widely used as a solvent in daily chemical, coating, and polymer industries.

[0003] At present, the main process for the large-scale industrial production of benzyl alcohol in China is the hydrolysis of benzyl chloride. The main reaction is essentially: Na2CO3 hydrolyzes to produce OH - , OH - At the oil-water interface, it reacts with benzyl chloride to form benzyl alcohol. The reaction is a liquid-liquid heterogeneous reaction. The controlling step of the reaction rate is OH - Diffusion at the liquid-liquid interface, the selectivity of the main reaction is 85% to 88%. The side reaction is essentially the etherification reaction of benzyl alcohol and benzyl chloride, and the reaction rate is controlled by the contact and collision of benzyl alcohol and benzyl chloride molecules in the oil phase. The main and side reactions are tandem competitive reactions, and the size of the oil phase droplets in the reaction liquid, the total contact area between the phases and OH - The concentration between the liquid-liquid phases is the main factor affecting the selectivity of the main and side reactions.

[0004] The existing reaction process is a fully mixed flow continuous reactor, which adopts a multi-layer blade method combining a propulsion stirring paddle and a paddle stirring paddle, and uses the shear force of the blade to disperse the oil phase droplets to achieve the reaction conditions of sufficient mixing of the oil / water phase. However, because the oil / water phase needs to be naturally settled and separated after the reaction, the density of the Na2CO3 solution put into the reaction must be greater than the density of benzyl chloride to maintain a large density difference between the oil / water phase of the reaction liquid. During the reaction process, on the one hand, the shear force of stirring causes the oil phase droplets to break and disperse, and on the other hand, due to the density difference and the interfacial tension of the oil / water phase, the oil phase droplets have a tendency to float and coalesce. The two opposite effects cause the size of the oil phase droplets to not be very small under the condition of liquid-liquid heterogeneity, and the size distribution is at the millimeter and centimeter level, and the oil / water phase is not fully mixed. The selectivity of the main reaction is 85% to 88%, which is the average level of the reaction under the current mixing conditions. In addition, in the industrial production of benzyl alcohol, since the industrial value of dibenzyl ether is less than that of benzyl alcohol, there is a benefit demand for producing more benzyl alcohol and less dibenzyl ether per unit raw material input. Therefore, it is urgent to solve the problems of low selectivity and low yield of production reactions in the prior art. Summary of the invention

[0005] In view of this, the present invention proposes a method and a device for improving the reaction selectivity and yield of benzyl alcohol industrial production.

[0006] The technical solution of the present invention is achieved as follows: On the one hand, the present invention provides a method for improving the selectivity and yield of the industrial production reaction of benzyl alcohol, comprising the following steps:

[0007] S1, mixing benzyl chloride and an alkali solution, and injecting the mixture into a hydrolysis reactor for hydrolysis reaction;

[0008] S2, cooling after the reaction, adding NaCl solution and mixing evenly, and then entering the oil-water separator to separate into oil phase material and water phase material;

[0009] S3, the oil phase material enters a distillation tower and is distilled to obtain benzyl alcohol.

[0010] On the basis of the above technical solution, preferably, in step S1, the mass concentration of the alkaline solution is 3.54%-5.94%, and the feed mass flow ratio of benzyl chloride:alkaline solution is 1:(5.788-9.712).

[0011] On the basis of the above technical solution, preferably, in step S2, the NaCl solution is a saturated NaCl solution (mass fraction), and the feed mass flow ratio of the saturated NaCl solution:benzyl chloride is (1.702-5.171):1.

[0012] On the basis of the above technical solution, preferably, the source of NaCl in the saturated NaCl solution is: sodium chloride crystalline salt precipitated after evaporation and crystallization of the aqueous phase material in step S2.

[0013] On the basis of the above technical solution, preferably, the alkaline solution is an alkaline solution prepared by recycling water and caustic soda flakes after evaporation and condensation of the aqueous phase material.

[0014] On the basis of the above technical solution, preferably, the hydrolysis reaction temperature is 80-150° C., and the reaction residence time is 6-10 h.

[0015] On the other hand, the present invention also provides a device for improving the reaction selectivity and yield of benzyl alcohol industrial production, comprising a benzyl chloride feed pipe, a recovery water pipe, a NaOH solution pipe, a NaCl solution pipe, a reactor, a heat exchanger, an oil-water separator and a distillation tower; the NaOH solution pipe, the reactor, the heat exchanger, the oil-water separator and the distillation tower are connected in sequence through pipelines, the recovery water pipe and the benzyl chloride feed pipe are connected in sequence with the NaOH solution pipe through a tee, and the pipeline between the oil-water separator and the distillation tower is connected to the NaCl solution pipe.

[0016] On the basis of the above technical scheme, preferably, it also includes an evaporator, a condenser and a crystallizer separator, the water phase outlet of the oil-water separator is connected to the evaporator and the crystallizer separator in sequence, and the evaporator, condenser and recovery water pipe are connected in sequence; the discharge port of the crystallizer is connected to the NaCl solution pipe, and the recovery water pipe is connected to the NaCl solution pipe through a tee.

[0017] On the basis of the above technical solution, preferably, the benzyl chloride feed pipe, the recovery water pipe, the NaOH solution pipe and the NaCl solution pipe are all provided with automatic regulating valves and flow meters.

[0018] On the basis of the above technical solution, preferably, the NaOH solution pipe between the recovery water pipe and the benzyl chloride feed pipe is provided with a 1# density meter and a 1# static mixer, the benzyl chloride feed pipe is provided with a 2# density meter, and the NaOH solution pipe between the benzyl chloride feed pipe and the reactor is provided with a 2# static mixer.

[0019] The method and device for improving the selectivity and yield of the industrial production reaction of benzyl alcohol of the present invention have the following beneficial effects compared with the prior art:

[0020] (1) Oil / water phase separation requires a certain density difference. The present invention increases the density of the water phase by adding NaCl solution to the reaction solution, so that the oil / water phase entering the sedimentation process can be completely separated, thereby ensuring complete separation of the oil / water phase, thereby improving the selectivity of the reaction and the yield of benzyl alcohol.

[0021] (2) The present invention uses the water recovered from the aqueous phase and the NaCl crystallized as raw materials to achieve full recovery of the reaction products, reduce the cost of industrial production of benzyl alcohol, and improve economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a comparison chart of the difference in surface tension coefficients of the oil / water phase interface;

[0024] Figure 2 is the density difference between benzyl alcohol and dibenzyl ether at different temperatures;

[0025] Figure 3 Density changes at different ratios of benzyl alcohol and dibenzyl ether

[0026] Figure 4It is the density curve of oil phase and water phase under different reaction conversion rates;

[0027] Figure 5 It is the density difference curve of oil phase and water phase under different reaction conversion rates;

[0028] Figure 6 The density curve of oil-water phase at different reaction efficiencies when the mass concentration of NaOH solution is 5.94% as the reaction raw material;

[0029] Figure 7 The density difference curve of oil-water phase at different reaction efficiencies is a graph of NaOH solution with a mass concentration of 5.94% as the reaction raw material;

[0030] Figure 8 The density curve of oil-water phase at different reaction efficiencies when the mass concentration of NaOH solution is 3.54% as the reaction raw material;

[0031] Fig. 9 The density difference curve of oil-water phase at different reaction efficiencies is a graph of NaOH solution with a mass concentration of 3.54% as the reaction raw material;

[0032] Fig.10 The process of the present invention Figure I ;

[0033] Fig.11 The process of the present invention Figure II ;

[0034] Fig.12 This is a comparison chart of reaction selectivity and benzyl alcohol yield.

[0035] In the figure, 1-benzyl chloride feed pipe, 2-recovery water pipe, 3-NaOH solution pipe, 4-NaCl solution pipe, 5-reactor, 6-heat exchanger, 7-oil-water separator, 8-distillation tower, 9-evaporator, 10-condenser, 11-crystallizer, 12-automatic regulating valve, 13-flow meter, 14-1#densitometer, 15-1#static mixer, 16-2#densitometer, 17-2#static mixer, 121-1#automatic regulating valve, 131-1#flow meter, 122-2#automatic regulating valve, 132-2#flow meter, 123-3#automatic regulating valve, 133-3#flow meter, 124-4#automatic regulating valve, 134-4#flow meter, 18-1#control operator, 19-controller, 20-2#control operator, 21-3#control operator. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Under the existing production equipment conditions, the shear strength of stirring is constant. To strengthen the mixing of liquid-liquid heterogeneous phases, that is, to reduce the size of oil phase droplets, it is necessary to suppress the floating and coalescence tendency of oil phase droplets. The sedimentation rate of oil droplets affects the floating tendency of droplets; the interfacial tension of oil / water phase affects the coalescence tendency of oil droplets.

[0038] Sedimentation velocity

[0039] Where g is the acceleration due to gravity, d is the average diameter of the oil phase droplets, ρs is the density of the oil phase, ρ is the density of the water phase, and μ is the viscosity of the water phase. The factors affecting the sedimentation velocity are the oil droplet size d and the density difference (ρ s -ρ), d and u are all indicators that need to be reduced in this technical solution. When the density difference is 0, u is 0, and d will be reduced to the minimum value under the same shear strength.

[0040] The interfacial tension of the oil / water phase is related to the difference in surface tension coefficients between the oil phase and the water phase. The smaller the difference in surface tension coefficients, the smaller the interfacial tension of the oil / water phase and the smaller the tendency of oil droplets to coalesce.

[0041] From chemical simulation analysis Figure 1 From the above, we can see that the surface tension coefficient of both Na2CO3 solution and NaOH solution decreases with the decrease of concentration. That is, the lower the concentration, the smaller the difference of surface tension coefficient between water phase and oil phase, the smaller the interfacial tension of oil / water phase, and the smaller the tendency of agglomeration.

[0042] As the concentration of water phase decreases, the density of water phase will decrease, and the decrease of the density difference between oil and water phase and the decrease of the difference of surface tension coefficient are in the same direction. That is, the trend of suppressing the floating and coalescence of oil droplets can be achieved at the same time.

[0043] By reducing the concentration of Na2CO3 solution, the amount of Na2CO3 required for the reaction is constant, the flow rate of Na2CO3 solution will increase, and the average residence time of the reaction will decrease. - The concentration between the liquid and liquid phases decreases, and the main reaction rate decreases. Under the existing equipment conditions, the reaction will not be completely completed.

[0044] The main reaction is: Na2CO3 hydrolysis produces OH -OH- diffuses to the oil-water interface and reacts with benzyl chloride to form benzyl alcohol. The reaction is a liquid-liquid heterogeneous reaction. The controlling step of the reaction rate is the diffusion of OH- at the liquid-liquid interface.

[0045]

[0046]

[0047] OH- produced by the equilibrium ionization hydrolysis of the solution participates in the reaction. The concentration of OH- is much lower than that of Na2CO3. If a strong base is used instead of Na2CO3, the concentration of OH- in the reaction solution will increase instead of decrease when the concentration is reduced to make the density difference 0, thereby not reducing the overall reaction rate.

[0048] Reaction formula after adjusting the process:

[0049] Main reaction:

[0050] Side effects:

[0051] After the reaction, the oil / water phase separation requires a certain density difference. By adding saturated NaCl solution to the reaction liquid to increase the density of the water phase, the oil / water phase entering the sedimentation process can be completely separated. The saturated NaCl solution is provided by the mother liquor of the MVR system.

[0052] The simulation calculations using chemical simulation software are as follows:

[0053] (1) Density differences between benzyl alcohol and dibenzyl ether at different temperatures

[0054] Figure 2 It can be seen that in the range of 50℃~100℃, Δρ=ρbenzyl alcohol-ρdibenzyl ether, and the variation value of Δρ is 2.09~3.27kg / m 3 , the density of Δρ / ρbenzyl alcohol is 0.2%~0.33%, and the density of Δρ / ρdibenzyl ether is 0.2%~0.33%. The density difference between benzyl alcohol and dibenzyl ether is very small.

[0055] (2) Density changes of binary mixtures of benzyl alcohol and dibenzyl ether at different contents of benzyl alcohol

[0056] Figure 3 It can be seen that when the benzyl alcohol content is 0% to 100%, the density changes from 979.3 to 982.7 kg / m 3 , the density variance is 1.29, and the density standard deviation is 1.13. The density of the benzyl alcohol-dibenzyl ether binary mixture changes little at different contents of benzyl alcohol.

[0057] based on Figure 2 and Figure 3The conclusion is that the effect of reaction selectivity on oil phase density under the same reaction conversion rate can be ignored. That is, when simulating the difference in oil / water phase density under different solution concentrations, the effect of reaction selectivity on density can be ignored.

[0058] (3) Density difference between oil phase and water phase under different reaction conversion rates calculated by original production process simulation

[0059] Figure 4 and Figure 5 It can be seen that the water phase density is greater than the oil phase density. As the reaction proceeds, the density difference gradually increases from 46 kg / m 3 Increased to 78kg / m 3 , average density difference 61.59kg / m 3 .

[0060] (4) Simulating the difference in oil / water phase density at different reaction conversion rates by using different concentrations of NaOH solution as the reaction raw material

[0061] Figure 6-9 It can be seen that, 5.94% NaOH solution: the density difference of the oil / water phase at the initial node of the reaction is 0; 3.54% NaOH solution: the average density difference of the entire reaction process is 0. As the concentration of the reaction raw material NaOH solution decreases, the density difference at the initial node of the reaction gradually decreases. When the density difference at the initial node drops to 0 at 5.94%, and the concentration continues to decrease, the density difference at the initial node rises in the opposite direction, and the average density difference of the entire reaction process will continue to decrease. When the average density difference of the entire reaction process drops to 0 at 3.54%, the concentration continues to decrease, and the density difference at the initial node and the average density difference of the entire reaction process both rise in the opposite direction. Therefore, the preferred range of NaOH concentration adopted in the technical scheme is 5.94% to 3.54%.

[0062] Under the original production process, after the reaction liquid was cooled and before entering the sedimentation process, the sample was taken at 50°C as the benchmark, and the oil phase density was measured to be 1012.42 kg / m 3 , the water phase density is 1078.61kg / m 3 The saturated NaCl solution added in the technical solution should increase the water phase density of the mixed reaction liquid before entering the sedimentation process to 1078.61 kg / m 3 Maintain the oil / water phase density difference required by the sedimentation process in the original production process to ensure the complete separation of the oil / water phase.

[0063] Based on different NaOH concentrations, the feed rates of other parameters were set as follows:

[0064]

[0065] Based on the above analysis, the present invention provides a device and method for improving the selectivity and yield of the industrial production reaction of benzyl alcohol, wherein the device comprises a benzyl chloride feed pipe 1, a recovery water pipe 2, a NaOH solution pipe 3, a NaCl solution pipe 4, a reactor 5, a heat exchanger 6, an oil-water separator 7 and a distillation tower 8. The benzyl chloride feed pipe 1, the recovery water pipe 2, the NaOH solution pipe 3 and the NaCl solution pipe 4 are all feed pipes for the corresponding raw materials; the reactor 5 is a continuous reactor for hydrolyzing benzyl chloride with an alkaline solution, and is composed of three reactors connected in series; the oil-water separator 7 is used to separate the oil phase and the water phase of the reaction product, and the distillation tower 8 is used for distilling the oil phase.

[0066] Among them, the NaOH solution pipe 3, the reactor 5, the heat exchanger 6, the oil-water separator 7 and the distillation tower 8 are connected in sequence through pipelines, the recovery water pipe 2 and the benzyl chloride feed pipe 1 are connected to the NaOH solution pipe 3 in sequence through a tee, and the pipeline between the oil-water separator 7 and the distillation tower 8 is connected to the NaCl solution pipe 4.

[0067] The recovered water and the NaOH solution are mixed to obtain a diluted NaOH solution, which is then mixed with benzyl chloride and introduced into the reactor 5 for hydrolysis reaction. After the reaction is completed, oil and water are separated, and the separated oil phase is distilled to obtain benzyl alcohol.

[0068] It also includes an evaporator 9, a condenser 10 and a crystal separator 11. The water phase outlet of the oil-water separator 7 is connected to the evaporator 9 and the crystal separator 11 in sequence. The evaporator 9, the condenser 10 and the recovery water pipe 2 are connected in sequence. The discharge port of the crystal separator 11 is connected to the NaCl solution pipe 4. The recovery water pipe 2 is connected to the NaCl solution pipe 4 through a three-way connection. On the one hand, the water phase is evaporated and condensed to obtain the recovered water, which is used to prepare the required NaOH solution. On the other hand, after the water phase is evaporated, the remaining material is crystallized, and sodium chloride crystals are precipitated, which are then mixed with a part of the recovered water to prepare the required NaCl.

[0069] The benzyl chloride feed pipe 1, the recovery water pipe 2, the NaOH solution pipe 3 and the NaCl solution pipe 4 are all provided with automatic regulating valves 12 and flowmeters 13, so as to facilitate the adjustment and control of the flow. Among them, the benzyl chloride feed pipe 1 is provided with a 1# automatic regulating valve 121 and a 1# flowmeter 131, the recovery water pipe 2 is provided with a 2# automatic regulating valve 122 and a 2# flowmeter 132, the NaOH solution pipe 3 is provided with a 3# automatic regulating valve 123 and a 3# flowmeter 133, and the NaCl solution pipe 4 is provided with a 4# automatic regulating valve 124 and a 4# flowmeter 134.

[0070] The NaOH solution pipe 3 between the recovery water pipe 2 and the benzyl chloride feed pipe 1 is provided with a 1# density meter 14 and a 1# static mixer 15, the benzyl chloride feed pipe 1 is provided with a 2# density meter 16, and the NaOH solution pipe 3 between the benzyl chloride feed pipe 1 and the reactor 5 is provided with a 2# static mixer 17.

[0071] 1# control operation unit 18 and 1# flow meter 131, 3# flow meter 133

[0072] The 1# flow meter 131 and the 3# flow meter 133 are electrically connected to the 1# control operator 18 and are both controlled by the 1# control operator 18 ; the 1# density meter 14 is electrically connected to the controller 19 , and the density value is set by the controller 19 .

[0073] The flowmeter 132 and the flowmeter 133 are electrically connected to the 2# control operator 20, and the 3# control operator 21 is electrically connected to the 2# control operator 20 and the 4# automatic regulating valve 124. The 2# control operator 20 adds the flow values ​​of the flowmeter 132 and the flowmeter 133 and feeds them back to the 3# control operator 21; the 3# control operator 21 multiplies the flow sum value by the set ratio to obtain the flow control value and feeds it back to the 4# automatic regulating valve 124.

[0074] Example

[0075] Based on the above device, taking the production of benzyl chloride with a feed flow rate of 10 t / h as an example, the method for improving the selectivity and yield of the industrial production reaction of benzyl alcohol in this embodiment comprises the following steps:

[0076] S1, benzyl chloride feed flow rate is 10 t / h, and the flow value is controlled by 1# automatic regulating valve 121.

[0077] S2, prepare concentrated NaOH solution with caustic soda flakes and recycled water, with a mass concentration of 20%. The feed flow of concentrated NaOH solution is controlled by 3# automatic regulating valve 123, and the flow value is proportionally controlled. The flow ratio of 3# flow meter / 1# flow meter is 1.65-1.75, which is set by 1# control operator 18.

[0078] S3, the feed flow of recycled water is controlled by 2# automatic regulating valve 122, and 2# flow meter 132 is set before the regulating valve, and the flow is controlled by density after mixing. After the recycled water and concentrated NaOH solution pipelines are merged, they are fully mixed by 1# static mixer 15, and 1# density meter 14 is set after 1# static mixer 15, and the density value is set by controller 19.

[0079] S4, the diluted NaOH solution mixed in step S3 is used as a raw material, combined with benzyl chloride, fully mixed through the 2# static mixer 17, and enters the continuous reactor 5 for hydrolysis reaction, the reaction temperature is 130° C., and the reaction residence time is 8 hours.

[0080] S5, after the reaction liquid leaves the reactor 5, it is cooled by the heat exchanger 6.

[0081] S6, the NaCl solution is statically mixed with the reaction liquid after cooling and then enters the oil-water separator 7, the separated oil phase enters the distillation tower 8 for distillation to obtain benzyl alcohol; the separated water phase is evaporated by the evaporator 9, the steam is condensed by the condenser 10 to obtain recycled water, the material at the bottom is passed through the crystallization separator 11 to precipitate NaCl crystals, the crystals and a part of the recycled water are used to prepare a NaCl saturated solution; the other part of the recycled water is used as a part of the raw material to prepare a NaOH solution.

[0082] The flow rate of NaCl solution is controlled by 4# automatic regulating valve 124, and 4# flow meter 134 is set in front of the regulating valve. 2# control operator 20 adds the flow values ​​of 3# flow meter 133 and 2# flow meter 132 and feeds them back to 3# control operator 21; 3# control operator 21 multiplies the flow sum value by the set ratio to obtain the flow control value and feeds it back to 4# automatic regulating valve 124.

[0083] The oil / water phase separation requires a certain density difference. By adding saturated NaCl solution to the reaction liquid to increase the density of the water phase, the oil / water phase entering the sedimentation process can be completely separated.

[0084] Related formula: Q3=Q1×N 18 ;

[0085] Among them, Q3 is the flow control value of concentrated NaOH solution, Q1 is the feed flow value of benzyl chloride, N 18 It is the setting value of control operator 18#.

[0086] Purpose: To control the flow rate of NaOH entering the reaction by using the feed flow rate of benzyl chloride and the set No. 1 control operator 18, so as to ensure that NaOH is excessive during the reaction, the benzyl chloride reacts completely, and prevent the benzyl chloride from corroding the reactor and causing a safety accident.

[0087] Q4=(Q 133 +Q 132 )×N 21 ;

[0088] Among them, Q4 is the flow control value of NaCl, Q 133 is the flow value of 3# flow meter 133, Q 132 is the flow value of 2# flow meter 132, N 21 It is the setting value of the 3# control operator 21, and the setting value is taken from the data of the software simulation calculation.

[0089] Purpose: Q133 and Q 132 The flow rate determines the water phase density of the reaction liquid during and after the reaction, and the required oil / water phase density difference during the reaction. 21The flow rate of Q4 is controlled so that after the reaction liquid is mixed with the mother liquor, the density difference of the oil / water phase rises to the density difference of the original process, so as to ensure that the oil / water phase in the subsequent sedimentation process is completely separated.

[0090] Based on different embodiments of the present invention, the control parameters are set as follows:

[0091]

[0092] Based on different embodiments of the present invention, the economic benefits are calculated as follows:

[0093]

[0094] The data in the above table show that after adding NaCl, the yield of benzyl alcohol of the present invention is as high as 93% or more ( Fig.12 ), which is significantly higher than the comparative example; in addition, compared with the comparative example, the cost per hour of the present invention saves more than 1,400 yuan. The present invention not only realizes the full recovery of the reaction products (recovered water and NaCl crystal salt), but also reduces the cost of industrial production of benzyl alcohol, improves the economic benefit, and is suitable for industrial production of benzyl alcohol.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving the reaction selectivity and yield of benzyl alcohol industrial production, characterized in that: The following steps are involved: S1, mixing benzyl chloride and an alkali solution, and injecting the mixture into a hydrolysis reactor for hydrolysis reaction; S2, cooling after the reaction, adding NaCl solution and mixing evenly, and then entering the oil-water separator to separate into oil phase material and water phase material; S3, the oil phase material enters a distillation tower and is distilled to obtain benzyl alcohol.

2. A method for improving the reaction selectivity and yield of benzyl alcohol industrial production according to claim 1, characterized in that: In step S1, the mass concentration of the alkaline solution is 3.54%-5.94%, and the feed mass flow ratio of benzyl chloride:alkaline solution is 1:(5.788-9.712).

3. A method for improving the reaction selectivity and yield of benzyl alcohol industrial production according to claim 1, characterized in that: In step S2, the NaCl solution is a saturated NaCl solution, and the feed mass flow ratio of the saturated NaCl solution to benzyl chloride is (1.702-5.171):

1.

4. A method for improving the reaction selectivity and yield of benzyl alcohol industrial production as claimed in claim 3, characterized in that: The source of NaCl in the saturated NaCl solution is: the sodium chloride crystal salt precipitated after the aqueous phase material in step S2 is evaporated and crystallized.

5. A method for improving the reaction selectivity and yield of benzyl alcohol industrial production according to claim 1, characterized in that: The alkaline solution is an alkaline solution prepared by recycling water and caustic soda flakes after evaporation and condensation of aqueous phase materials.

6. A method for improving the reaction selectivity and yield of benzyl alcohol industrial production according to claim 1, characterized in that: The hydrolysis reaction temperature is 80-150°C, and the reaction residence time is 6-10h.

7. A device for improving the reaction selectivity and yield of benzyl alcohol industrial production, characterized in that: It comprises a benzyl chloride feed pipe (1), a water recovery pipe (2), a NaOH solution pipe (3), a NaCl solution pipe (4), a reaction kettle (5), a heat exchanger (6), an oil-water separator (7) and a distillation tower (8); The NaOH solution pipe (3), the reaction kettle (5), the heat exchanger (6), the oil-water separator (7) and the distillation tower (8) are connected in sequence through pipelines. The water recovery pipe (2) and the benzyl chloride feed pipe (1) are connected to the NaOH solution pipe (3) in sequence through a tee, and the pipeline between the oil-water separator (7) and the distillation tower (8) is connected to the NaCl solution pipe (4).

8. A device for improving the selectivity and yield of benzyl alcohol industrial production reaction as claimed in claim 7, characterized in that: It also includes an evaporator (9), a condenser (10) and a crystallizer (11), The water phase outlet of the oil-water separator (7) is connected to the evaporator (9) and the crystallizer (11) in sequence, and the evaporator (9), the condenser (10) and the recovery water pipe (2) are connected in sequence; The discharge port of the crystal separator (11) is connected to the NaCl solution pipe (4), and the recovery water pipe (2) is connected to the NaCl solution pipe (4) via a tee.

9. A device for improving the selectivity and yield of benzyl alcohol industrial production reaction as claimed in claim 8, characterized in that: The benzyl chloride feed pipe (1), the recovery water pipe (2), the NaOH solution pipe (3) and the NaCl solution pipe (4) are all provided with an automatic regulating valve (12) and a flow meter (13).

10. A device for improving the selectivity and yield of benzyl alcohol industrial production reaction as claimed in claim 9, characterized in that: The NaOH solution pipe (3) between the recovery water pipe (2) and the benzyl chloride feed pipe (1) is provided with a #1 density meter (14) and a #1 static mixer (15), the benzyl chloride feed pipe (1) is provided with a #2 density meter (16), and the NaOH solution pipe (3) between the benzyl chloride feed pipe (1) and the reaction kettle (5) is provided with a #2 static mixer (17).

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