Method for removing acrolein in industrial epichlorohydrin production process

Abstract

The invention discloses a method for removing acrolein in an industrial epichlorohydrin production process. The method comprises the following steps: constructing an extraction-removal linkage circulating device comprising an extraction device, an acrolein removal reactor and a separation device; the method comprises the following steps: respectively introducing an oil-phase to-be-treated liquid obtained in an industrial epoxy chloropropane production process and a water-phase extraction agent into an extraction device, extracting, discharging an oil phase obtained after acrolein is extracted from the extraction device, and directly feeding into a downstream finished product tower; the method comprises the following steps: introducing an acrolein-extracted water phase into an acrolein removal reactor, adding a remover into the acrolein removal reactor, fully reacting, separating by a separation device, and directly returning the obtained water phase to an extraction device for recycling. According to the removal method disclosed by the invention, an extraction-removal linkage circulating device is directly introduced into an existing industrial production process flow, so that continuous production is ensured, and meanwhile, high-efficiency removal of acrolein and high yield of epichlorohydrin can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology, and particularly to a method for removing acrolein in the process of industrial production of epichlorohydrin. Background Art

[0002] Epichlorohydrin, also known as epichlorohydrin, is an important organic chemical raw material and fine chemical product. Currently, 85% of it is used in the production of epoxy resin. Epoxy resin has advantages such as high adhesiveness, small shrinkage, good stability, excellent dielectric capacity, chemical corrosion resistance, and high impact strength resistance. It is mainly used to manufacture coatings, adhesives, composite reinforcement materials, etc., and plays a crucial role in many fields such as automobiles, construction, electronics, electric power, and food packaging.

[0003] Currently, the global market has a very large demand for epichlorohydrin. The processes applied to industrial production of epichlorohydrin include propylene chlorination method, allyl acetate method, and glycerol chlorination method. In recent years, the market price of propylene has gradually increased, and the propylene chlorination method and allyl acetate method are prone to generating a large amount of wastewater and waste residue, increasing the difficulty of pollution treatment. These factors have gradually led to the abandonment of the propylene chlorination method and allyl acetate method.

[0004] In contrast, the glycerol method for producing epichlorohydrin has a high technical maturity and a relatively stable production process. At the same time, the output of glycerol, a by-product of biodiesel used as a reaction raw material in recent years, has been increasing year by year. Under such circumstances, the production method of preparing epichlorohydrin by the glycerol method has been more widely applied.

[0005] In the process of producing epichlorohydrin by the glycerol method, the existing product purification process is as Figure 1 shown. The reaction liquid composition from the cyclization tower includes: epichlorohydrin, 1,3-dichloropropanol, 2,3-dichloropropanol, water, and acrolein. Among them, the content of epichlorohydrin is 85 - 90 wt%, and the content of acrolein is 1.0 - 2.5 wt%. The specific values fluctuate due to process differences between batches. This reaction liquid first enters the low-boiling tower for rectification separation. Acrolein and water with lower boiling points and part of epichlorohydrin rise to the top of the tower. After the overhead distillate passes through the liquid separation device, the aqueous phase is transported back to the previous process for reuse. Since the oil phase still contains epichlorohydrin, it is re-circulated to the low-boiling tower for secondary rectification and purification. The materials remaining in the tower bottom have removed water and low-boiling acrolein and mainly contain higher-purity epichlorohydrin and other high-boiling substances, which will be sent to the subsequent finished product tower for further purification.

[0006] However, in the above-mentioned purification process of epichlorohydrin, no reasonable removal process is designed for the by-product acrolein, resulting in its continuous circulation and accumulation during the production process of epichlorohydrin. When the low-boiling tower continuously processes the reaction liquid from the cyclization tower, the concentration of acrolein inside becomes higher and higher. Once the mass ratio reaches 10wt% - 15wt%, acrolein is extremely prone to random polymerization, generating a large amount of insoluble solids, leading to blockages in many places such as the packing and trays of the low-boiling tower. The polymerized acrolein is difficult to handle, making the low-boiling tower unable to operate normally and requiring shutdown for maintenance, bringing additional production inputs. From the perspective of environmental protection and safety, the irritating and tear-inducing gases emitted by these acroleins are likely to cause environmental pollution and endanger the health of the staff.

[0007] Therefore, developing and designing a suitable process to remove the acrolein light component generated during the preparation of epichlorohydrin by the glycerol method is an urgent problem to be solved at present.

[0008] Chinese patent document with the application publication number CN108752292A introduces a method for recovering epichlorohydrin based on epichlorohydrin light components. The content of each component in the epichlorohydrin light components disclosed in its specific implementation is 46.6wt% epichlorohydrin, 15.6wt% acrolein, 25.9wt% dichloroethylene, 11.2wt% chloroform, and 0.7wt% impurities. This method makes acrolein dimerize or polymerize by adding triethylamine or triethanolamine as a treatment agent in the epichlorohydrin light components to form a high-boiling acrolein polymer, and then successively performs atmospheric distillation and vacuum distillation to finally obtain epichlorohydrin. After adding the treatment agent triethylamine or triethanolamine, this method not only introduces new impurities, but more disadvantageously, the acrolein polymer will further polymerize during the distillation process, and finally form a viscous substance in the bottom of the tower, still wrapping part of the epichlorohydrin, resulting in incomplete recovery of epichlorohydrin; and the polymerized viscous substance cannot be incinerated. Even if, as described in it, using dichloroethylene and chloroform in the light components as solvents and incinerating them together with the viscous substance, the treatment effect is not good and a large amount of solvent is wasted.

[0009] There is also a need to remove acrolein in other systems. For example, Chinese patent document with the application publication number CN102199107A introduces a method for removing acrolein in acrylonitrile. It contacts the acrylonitrile raw material with 201 gel-type styrene and other anion exchange resins to remove acrolein in the raw material acrylonitrile. The maximum acrolein content that this method can handle is extremely low, and when the acrolein content in the system exceeds 25 ppm, the removal cannot be completed.

[0010] From the perspective of the cost and economic feasibility of industrial production, the amount of acrolein that can be processed by a unit adsorbent in the physical adsorption method is extremely limited. Therefore, a specific remover is selected to react chemically with acrolein to complete the removal of acrolein. However, in this process, the loss of epichlorohydrin needs to be minimized as much as possible. Due to the presence of the epoxy bond, epichlorohydrin has high reactivity and is easily attacked by nucleophiles or electrophiles to open the ring, which results in the risk of consumption of epichlorohydrin during the reaction to remove acrolein.

[0011] Based on the above situation, there is still no effective method for removing acrolein in the industrial production process of epichlorohydrin, especially in the process of producing epichlorohydrin by the glycerol method. Summary of the Invention

[0012] Aiming at the deficiencies of the prior art, the present invention discloses a method for removing acrolein in the industrial production process of epichlorohydrin. An extraction-removal linkage circulation device is directly introduced into the existing industrial production process flow, which ensures continuous production and at the same time can ensure the efficient removal of acrolein and the high yield of epichlorohydrin.

[0013] The specific technical solution is as follows:

[0014] A method for removing acrolein in the industrial production process of epichlorohydrin, comprising the following steps:

[0015] (1) Set up an extraction-removal linkage circulation device;

[0016] The extraction-removal linkage circulation device includes an extraction device, an acrolein removal reactor, and a separation device;

[0017] (2) The reaction liquid from the cyclization tower in the industrial production process of epichlorohydrin is fed into a de-bottoming tower for rectification separation. The distillate at the top of the de-bottoming tower enters a liquid separation device for separation, and the separated oil phase is the oil phase to be treated;

[0018] (3) The oil phase to be treated and the aqueous phase extractant are respectively fed into the extraction device in the extraction-removal linkage circulation device. After extraction, the oil phase after acrolein is extracted is discharged from the extraction device and directly sent to the downstream finished product tower; the aqueous phase that has extracted acrolein is fed into the acrolein removal reactor in the extraction-removal linkage circulation device, and a remover is added to the acrolein removal reactor. After sufficient reaction, it is separated by the separation device, and the obtained aqueous phase is directly returned to the extraction device for recycling.

[0019] In step (1):

[0020] Preferably, the bed volume of the extraction device is 300-1000 mL;

[0021] More preferably, the bed volume is 700 - 1000 mL.

[0022] The extraction device is internally filled with packing, selected from conventional types in the art, such as triangular spiral 316L stainless steel, wire ring 316L stainless steel, conjugate ring 316L stainless steel, rectangular saddle ring ceramics, etc.

[0023] The extraction device is externally provided with a jacket, and the extraction temperature can be regulated by setting the jacket.

[0024] Preferably, the temperature of the jacket is controlled to be 0 - 25 °C.

[0025] More preferably, the temperature of the jacket is controlled to be 0 - 10 °C.

[0026] In step (3):

[0027] The oil-phase liquid to be treated comprises water, epichlorohydrin and acrolein.

[0028] In the oil-phase liquid to be treated, the mass proportion of acrolein is 1 - 30 wt%.

[0029] In addition, the oil-phase liquid to be treated also includes a small amount of 1,3-dichloropropanol and 2,3-dichloropropanol.

[0030] The aqueous-phase extractant is selected from pure water or the recycled aqueous phase.

[0031] During the first extraction, the added aqueous-phase extractant is pure water. After one cycle, after removing acrolein from the aqueous phase that has extracted acrolein, the obtained aqueous phase is used as the aqueous-phase extractant for continuous extraction.

[0032] Preferably, the flow rate of the oil-phase liquid to be treated is 3 - 5 mL / min.

[0033] Preferably, the flow rate of the aqueous-phase extractant is 9 - 20 mL / min; more preferably 12 - 20 mL / min.

[0034] Preferably, the flow rate ratio of the oil-phase liquid to be treated to the aqueous-phase extractant is 1:(1 - 5); more preferably 1:(3 - 5).

[0035] The flow rates of the oil-phase liquid to be treated and the aqueous-phase extractant can be controlled respectively by a piston pump.

[0036] Preferably, the remover includes an oxidant and an alkaline substance.

[0037] More preferably:

[0038] The oxidant is selected from one or more of hydrogen peroxide, sodium hypochlorite, and calcium hypochlorite.

[0039] The alkaline substance is selected from one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water;

[0040] More preferably:

[0041] The oxidizing agent is selected from hydrogen peroxide;

[0042] The alkaline substance is selected from one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

[0043] Preferably:

[0044] The mass ratio of the removing agent to the aqueous phase extracting acrolein is 1:(10 - 150);

[0045] The mass ratio of the alkaline substance to the oxidizing agent is 1:(5 - 30).

[0046] Further preferably:

[0047] When the mass ratio of acrolein in the oil-phase liquid to be treated is 1 - 5 wt%;

[0048] The mass ratio of the removing agent to the aqueous phase extracting acrolein is 1:(100 - 150);

[0049] The mass ratio of the alkaline substance to the oxidizing agent is 1:(20 - 30).

[0050] When the mass ratio of acrolein in the oil-phase liquid to be treated is 5 - 15 wt%;

[0051] The mass ratio of the removing agent to the aqueous phase extracting acrolein is 1:(20 - 100);

[0052] The mass ratio of the alkaline substance to the oxidizing agent is 1:(10 - 20).

[0053] When the mass ratio of acrolein in the oil-phase liquid to be treated is 15 - 30 wt%;

[0054] The mass ratio of the removing agent to the aqueous phase extracting acrolein is 1:(10 - 20);

[0055] The mass ratio of the alkaline substance to the oxidizing agent is 1:(5 - 10).

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] The present invention processes the oil phase part of the distillate at the top of the low-boiling tower in the current industrial production process of epichlorohydrin. By directly introducing an extraction-removal linkage circulation device into the existing process flow, the acrolein and epichlorohydrin in the oil phase liquid to be treated are effectively separated using an aqueous phase extraction process, and then the aqueous phase extracted with acrolein is treated with a remover with a specific dosage and composition. On the one hand, the efficient removal of acrolein is achieved, and on the other hand, the separated aqueous phase is recycled without any post-treatment, ensuring the removal effect and stable circulation of the extraction-removal linkage circulation device, thereby realizing the continuous industrial production of epichlorohydrin.

[0058] The main components of the oil phase after being treated by the extraction-removal linkage circulation device are epichlorohydrin and a small amount of 1,3-dichloropropanol and 2,3-dichloropropanol, which can be directly sent to the downstream finished product tower and separated and recycled after conventional treatment.

[0059] Using the method for removing acrolein in the industrial production process of epichlorohydrin disclosed in the present invention, the highest removal rate of acrolein can reach 98.9%, and the highest yield of epichlorohydrin can reach 99.9%. Brief Description of the Drawings

[0060] Figure 1 is a partial process flow schematic diagram of the production of epichlorohydrin by the glycerol chlorination method in the prior art;

[0061] Figure 2 is a schematic diagram of the extraction-removal linkage circulation device and the process flow disclosed in the present invention;

[0062] Figure 3 is a partial process flow schematic diagram of the method for removing acrolein in the industrial production process of epichlorohydrin disclosed in the present invention;

[0063] Figure 4 is a curve of acrolein removal using the process of Example 1;

[0064] Figure 5 is a curve of acrolein removal using the process of Comparative Example 1;

[0065] Figure 6 is a curve of acrolein removal using the process of Comparative Example 2. Detailed Embodiments

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those conditions not specified in the embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0067] The features and performance of the present invention will be further described in detail in conjunction with the following embodiments.

[0068] Figure 2 It is a schematic diagram of the extraction-removal linkage circulation device and process flow disclosed by the present invention. The extraction-removal linkage circulation device includes an extraction device, an acrolein removal reactor, and a filtration and centrifugal separation device that are connected in sequence.

[0069] The extraction device includes an upper sample inlet, a lower sample inlet, an upper sample outlet, and a lower sample outlet; in the industrial production process of epichlorohydrin, the reaction liquid from the cyclization tower is fed into the low-boiling tower for rectification separation. The distillate at the top of the low-boiling tower enters the liquid separation device for separation. The separated oil phase is the oil phase to be treated. This oil phase to be treated is stored in the oil-phase storage tank and sent into the extraction device through the upper sample inlet by the plunger pump 1; the aqueous-phase extractant is stored in the aqueous-phase storage tank and sent into the extraction device through the lower sample inlet by the plunger pump 2; since the density of the oil phase is greater than that of the aqueous phase, the oil phase to be treated will flow downward, and the aqueous-phase extractant will flow upward. During the process of the two-phase exchange flow, the acrolein in the oil phase to be treated will be extracted into the aqueous phase; finally, the oil phase after the extraction of acrolein flows out from the lower sample outlet of the extraction device, and the aqueous phase that has extracted acrolein flows out through the upper sample outlet of the extraction device.

[0070] The aqueous phase that has extracted acrolein is sent into the acrolein removal reactor and reacts fully with the removal agent added therein. After acrolein is polymerized, it is converted into a precipitate and separated by the filtration and centrifugal separation device and then treated as solid waste. The remaining aqueous phase is returned to the aqueous-phase storage tank for recycling.

[0071] Figure 3 It is a partial process flow schematic diagram of the method for removing acrolein in the industrial production process of epichlorohydrin disclosed by the present invention. The extraction-removal linkage circulation device disclosed by the present invention is combined with a partial process flow schematic diagram of the production of epichlorohydrin by the glycerol chlorination method in the prior art ( Figure 1 ) In the process flow of the production of epichlorohydrin by the glycerol chlorination method, the oil phase separated by the liquid separation device is fed into the extraction-removal linkage circulation device. The oil phase after the extraction of acrolein treated by the device is discharged from the extraction device and directly sent to the downstream finished product tower.

[0072] Example 1

[0073] (1) Select triangular spiral 316L stainless steel as the packing of the extraction device, fill it to a bed volume of 1000 mL of the extraction device, and there is a jacket outside the extraction device. Control the temperature of the jacket at 0 °C;

[0074] (2) Take the actual reaction liquid in industrial production - the oil-phase liquid to be treated a and store it in the oil-phase storage tank, controlling the temperature of the storage tank at 0 °C. The composition is: water 1 wt%, epichlorohydrin 85.0 wt%, acrolein 10.0 wt%, 1,3-dichloropropanol 1.5 wt%, 2,3-dichloropropanol 2.5 wt%; use pure water as the aqueous-phase extractant, store it in the aqueous-phase storage tank, and control the temperature of the storage tank at 0 °C;

[0075] (3) Open the valves at the upper and lower sample inlet ports of the extraction device, adjust the plunger pump 1 to control the flow rate of the oil-phase liquid to be treated a at 3 mL / min, adjust the plunger pump 2 to control the flow rate of the aqueous-phase extractant at 9 mL / min. After the bed layer in the extraction device is filled with liquid, open the valve at the lower sample outlet, and adjust the flow rate at the lower sample outlet to be the same as that at the upper sample inlet;

[0076] (4) Collect the liquids at the upper and lower sample outlet ports. Among them, transfer the aqueous phase extracted with acrolein flowing out from the upper sample outlet to the acrolein removal reactor for treatment; the oil phase with acrolein extracted flowing out from the lower sample outlet is directly sent to the downstream finished product tower.

[0077] (5) Use a mixed solution of hydrogen peroxide (30 wt% hydrogen peroxide aqueous solution) and sodium hydroxide as the remover. The mass ratio of the remover to the aqueous phase extracted with acrolein is 1:30, and the mass ratio of the alkali substance to the oxidant in the remover is 1:15. The initial pH in the acrolein removal reactor is adjusted to 12.3, the rotation speed is 300 rpm, and after reacting for 30 min at room temperature, the mixture is passed into the filtration and centrifugation separation device. After filtering off the precipitate, the aqueous phase is returned to the aqueous-phase storage tank for recycling as the aqueous-phase extractant; the precipitate obtained by filtration is treated as solid waste;

[0078] (6) After the circulation system is stable, take a sample from the oil phase with acrolein extracted at the lower sample outlet of the extraction device for gas-phase detection.

[0079] Using the process of this example for acrolein removal, the changes in the acrolein removal rate and epichlorohydrin yield with the operation time of the device are as Figure 4 shown. After stable operation for 8 h, the acrolein removal rate is 96.0%, and the epichlorohydrin yield is 99.7%.

[0080] Examples 2 - 4

[0081] The removal process is basically the same as that in Example 1, except that the bed volume of the extraction device is different. The specific effective volume and, after stable operation for 8 h in each example, the acrolein removal rate and epichlorohydrin yield are listed in Table 1 below.

[0082] Table 1

[0083]

[0084] Examples 5 - 6

[0085] The removal process is basically the same as that in Example 1, except that the temperatures maintained in the oil - phase storage tank, the water - phase storage tank, and the jacket of the extraction device are different. The temperatures maintained in the oil - phase storage tank, the water - phase storage tank, and the jacket of the extraction device are the same in the same example. The specific temperatures, and the removal rate of acrolein and the yield of epichlorohydrin after 8 h of stable operation in each example are listed in Table 2 below.

[0086] Table 2

[0087]

[0088] Examples 7 - 9

[0089] The removal process is basically the same as that in Example 1, except that the flow rate and / or the ratio between the oil - phase liquid to be treated a and the water - phase extractant are different. The specific ratios, and the removal rate of acrolein and the yield of epichlorohydrin after 8 h of stable operation in each example are listed in Table 3 below.

[0090] Table 3

[0091]

[0092] Examples 10 - 15

[0093] The removal process is basically the same as that in Example 1, except that the types of oxidants or alkaline substances used in the remover are different. The specific types, and the removal rate of acrolein and the yield of epichlorohydrin after 8 h of stable operation in each example are listed in Table 4 below.

[0094] Table 4

[0095]

[0096] Comparative Example 1

[0097] The removal process is basically the same as that in Example 1, except that in step (5), the mass ratio of the remover to the water phase extracting acrolein is replaced by 1:5.

[0098] When the process of this comparative example is used for acrolein removal, the changes in the acrolein removal rate and the epichlorohydrin yield with the operation time of the device are as Figure 5 shown. After 3 h of operation, the acrolein removal rate and the epichlorohydrin yield are comparable to those in Example 1. However, with the extension of the operation time, both the acrolein removal rate and the epichlorohydrin yield decrease significantly. After 8 h of operation, the acrolein removal rate is only 84.3%, and the epichlorohydrin yield is only 93.6%.

[0099] Comparative Example 2

[0100] The removal process is basically the same as that in Example 1, except that in step (5), the mass ratio of the alkali substance to the oxidant in the removing agent is replaced with 1:2.

[0101] Using the process of this comparative example for acrolein removal, the changes in the acrolein removal rate and epichlorohydrin yield with the operation time of the device are as Figure 6 shown. After 8 hours of operation, the acrolein removal rate is only 82.4%, and the epichlorohydrin yield is only 95.6%.

[0102] Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that in the extraction-removal linkage circulation device disclosed in the present invention, whether the extraction device can maintain excellent acrolein removal rate and epichlorohydrin yield during the circulation, the treatment of the circulating aqueous phase in the acrolein removal reactor is a key point. While removing acrolein in the aqueous phase, the added removing agent also needs to be consumed to a level that does not affect subsequent circulation. When the removing agent is in excess (Comparative Example 1) or the ratio of the alkali substance to the oxidant in the removing agent is unreasonable (Comparative Example 2), the removal effect and stable circulation ability of the extraction-removal linkage circulation device will be significantly affected.

[0103] Example 16

[0104] The removal process is basically the same as that in Example 1, except that:

[0105] In step (2), the oil-phase liquid to be treated b is used, and its composition is: 3 wt% water, 85.5 wt% epichlorohydrin, 1.5 wt% acrolein, 5 wt% 1,3-dichloropropanol, 5 wt% 2,3-dichloropropanol;

[0106] In step (5), the mass ratio of the removing agent to the aqueous phase extracting acrolein is 1:150, the mass ratio of sodium hydroxide to hydrogen peroxide in the removing agent is 1:30, and the initial pH in the acrolein removal reactor is adjusted to 11.5.

[0107] After testing, after 8 hours of stable operation, the acrolein removal rate is 98.9%, and the epichlorohydrin yield is 99.9%.

[0108] Example 17

[0109] The removal process is basically the same as that in Example 1, except that:

[0110] In step (2), the oil-phase liquid to be treated c is used, and its composition is: 1 wt% water, 65 wt% epichlorohydrin, 30 wt% acrolein, 1.5 wt% 1,3-dichloropropanol, 2.5 wt% 2,3-dichloropropanol;

[0111] In step (5), the mass ratio of the removing agent to the aqueous phase extracting acrolein is 1:15, the mass ratio of sodium hydroxide to hydrogen peroxide in the removing agent is 1:5, and the initial pH in the acrolein removal reactor is adjusted to 13.0.

[0112] After testing, after 8 h of stable operation, the removal rate of acrolein is 96.4%, and the yield of epichlorohydrin is 99.7%.

[0113] Comparative Example 3

[0114] The aqueous phase extracting acrolein flowing out from the upper sampling port of the extraction device in Example 16 was obtained and treated by the adsorption method. The specific process is as follows:

[0115] 10 g of the aqueous phase extracting acrolein was taken and mixed with 5 g of macroporous adsorption resin (AB-8), and adsorption treatment was carried out at normal temperature and 300 rpm for 5 h. The removal rate of acrolein is listed in Table 5 below.

[0116] Comparative Examples 4-6

[0117] The removal process was basically the same as that of Comparative Example 3, except that the grades of the macroporous adsorption resin were successively replaced with YKDH-4, YKDH-5, and D101, and the mass of each was 5 g. The removal rate of acrolein is listed in Table 5 below.

[0118] Comparative Example 7

[0119] The removal process was basically the same as that of Comparative Example 3, except that the macroporous adsorption resin was replaced with the same mass of activated carbon. The removal rate of acrolein is listed in Table 5 below.

[0120] Table 5

[0121] Number Type of adsorbent Removal rate of acrolein (%) Comparative Example 3 AB-8 85.0 Comparative Example 4 YKDH-4 83.2 Comparative Example 5 YKDH-5 71.0 Comparative Example 6 D101 79.7 Comparative Example 7 Activated carbon 83.1

[0122] Comparative Example 8

[0123] The aqueous phase extracting acrolein flowing out from the upper sampling port of the extraction device in Example 1 was obtained and treated by adding a polymerization initiator. The specific process is as follows:

[0124] 30 g of the aqueous phase extracting acrolein was transferred to a 50 mL closed reaction kettle container, 64.7 mg of ammonium persulfate was added as a polymerization initiator, and the removal rate of acrolein was tested after reacting at 90 °C and normal pressure for 5 h, which was 23.1%.

[0125] Comparative Example 9

[0126] The removal process was basically the same as that of Comparative Example 8, except that the polymerization initiator was replaced with 43.9 mg of azobisisobutyronitrile (AIBN).

[0127] After testing, the removal rate of acrolein was 30.6%.

[0128] Comparative Examples 10 - 13

[0129] The aqueous phase extracted with acrolein flowing out from the upper sample outlet of the extraction device in Example 16 was obtained and treated by the hydrogenation method. The specific process is as follows:

[0130] 30 g of the aqueous phase extracted with acrolein was transferred to a 50 mL sealed reaction kettle. In several comparative examples, 0.1 g of Pd / C, Pt / C, Rh / C, and Ru / C were respectively added as catalysts. After the reaction kettle was evacuated, hydrogen gas at 2.0 MPa was introduced, and the reaction was carried out at 80 °C for 5 h;

[0131] The removal rate data of acrolein are shown in Table 6 below:

[0132] Table 6

[0133]

[0134]

[0135] The above - disclosed are preferred embodiments, but the protection scope of the present invention is not limited thereto. Those of ordinary skill in the art can easily understand the spirit of the present invention based on the above - mentioned embodiments and make different extensions and changes. However, as long as they do not depart from the spirit of the present invention, they are within the protection scope of the present invention.

Claims

1. A method for removing acrolein in the process of industrial production of epichlorohydrin, characterized in that, It includes the following steps: (1) Set up an extraction-removal linkage circulation device; The extraction-removal linkage circulation device includes an extraction device, an acrolein removal reactor, and a separation device; (2) Feed the reaction liquid from the cyclization tower in the industrial production process of epichlorohydrin into the low-boiling tower for rectification separation. The distillate at the top of the low-boiling tower enters the liquid separation device for separation, and the separated oil phase is the oil phase to be treated; (3) Feed the oil phase to be treated and the aqueous phase extractant into the extraction device in the extraction-removal linkage circulation device respectively. After extraction, the oil phase after acrolein extraction is discharged from the extraction device and directly sent to the downstream finished product tower; the aqueous phase extracting acrolein is fed into the acrolein removal reactor in the extraction-removal linkage circulation device, and a removing agent is added to the acrolein removal reactor. After sufficient reaction, it is separated by the separation device, and the obtained aqueous phase is directly returned to the extraction device for recycling.

2. The method for removing acrolein in the process of industrial production of epichlorohydrin according to claim 1, characterized in that, In step (1): For the extraction device, the bed volume is 300 - 1000 mL; The extraction device is filled with packing inside and is equipped with a jacket outside.

3. The method for removing acrolein in the process of industrial production of epichlorohydrin according to claim 1, characterized in that, In step (3): The oil phase to be treated consists of water, epichlorohydrin, and acrolein; In the oil phase to be treated, the mass proportion of acrolein is 1 - 30 wt%. The aqueous phase extractant is selected from pure water or the recycled aqueous phase after treatment.

4. The method for removing acrolein in the industrial production process of epichlorohydrin according to claim 1, characterized in that, In step (3): The flow rate of the oil phase to be treated is 3 - 5 mL / min; The flow rate of the aqueous phase extractant is 9 - 20 mL / min; The flow rate ratio of the oil phase to be treated to the aqueous phase extractant is 1:(1 - 5).

5. The method for removing acrolein in the process of industrial production of epichlorohydrin according to claim 1, characterized in that, In step (3): The removing agent includes an oxidant and an alkaline substance; The mass ratio of the removing agent to the aqueous phase extracting acrolein is 1:(10 - 150); The mass ratio of the alkaline substance to the oxidant is 1:(5 - 30).

6. The method for removing acrolein in the industrial production process of epichlorohydrin according to claim 5, wherein: The oxidant is selected from one or more of hydrogen peroxide, sodium hypochlorite, and calcium hypochlorite; The alkaline substance is selected from one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water.

7. The method for removing acrolein in the industrial production process of epichlorohydrin according to claim 5, wherein: The oxidant is selected from hydrogen peroxide; The alkaline substance is selected from one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

8. The method for removing acrolein in the industrial production process of epichlorohydrin according to any one of claims 1 - 7, wherein: When the mass proportion of acrolein in the oil phase to be treated is 1 - 5 wt%; The mass ratio of the removing agent to the aqueous phase extracting acrolein is 1:(100 - 150); The mass ratio of the alkaline substance to the oxidant is 1:(20 - 30).

9. The method for removing acrolein in the industrial production process of epichlorohydrin according to any one of claims 1 - 7, wherein: When the mass proportion of acrolein in the oil phase to be treated is 5 - 15 wt%; The mass ratio of the remover to the aqueous phase extracting acrolein is 1:(20-100); The mass ratio of the alkaline substance to the oxidant is 1:(10-20).

10. The method for removing acrolein in the industrial production process of epichlorohydrin according to any one of claims 1 to 7, characterized in that: When in the oil-phase liquid to be treated, the mass percentage of acrolein is 15-30 wt%; The mass ratio of the remover to the aqueous phase extracting acrolein is 1:(10-20); The mass ratio of the alkaline substance to the oxidant is 1:(5-10).

Images