A method for the continuous production of epichlorohydrin
By alternating the operation of a parallel fixed-bed reactor and an oil-water separator, the problems of catalyst deactivation and intermittent shutdowns during oil-water separation were solved, enabling efficient and continuous production of epichlorohydrin and improving production efficiency and product quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2026-03-17
AI Technical Summary
In existing technologies, the direct epoxidation of propylene chloride in industrial production requires catalyst deactivation and regeneration, and oil-water separation necessitates intermittent shutdowns, which affects production efficiency and increases costs.
The epoxidation reaction and catalyst regeneration are carried out alternately by a first fixed-bed reactor and a second fixed-bed reactor connected in parallel, and multiple oil-water separators are connected in parallel for continuous operation to ensure that the catalyst always operates at high efficiency and oil-water separation is carried out continuously.
This approach achieves stable catalyst activity and continuous production, improves production efficiency, reduces costs, produces fewer byproducts, and results in high selectivity and yield of epichlorohydrin.
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Figure CN117924218B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of epichlorohydrin production technology, and specifically relates to a method for continuous production of epichlorohydrin. Background Technology
[0002] Epichlorohydrin is a highly functional chemical process raw material and organic intermediate, widely used in the preparation of epoxy resins, chlorohydrin rubbers, plasticizers, and ion exchange resins. Currently, the main methods for preparing epichlorohydrin include the high-temperature chlorination of propylene, the propylene acetate method, the glycerol chlorination method, and the direct epoxidation of allyl chloride. Among these, the first three processes all involve a final step of dichloropropanol saponification, which generates large amounts of chlorinated wastewater and chloride salt residue.
[0003] The direct epoxidation of allyl chloride using titanium silicate molecular sieves as catalysts is the most promising green synthesis technology for epichlorohydrin, boasting advantages such as low energy consumption and environmental friendliness. Once industrialized, this process will become a major focus of production transformation and the mainstream technology for epichlorohydrin production.
[0004] The direct epoxidation of allyl chloride in industrial production using a fixed-bed reactor offers advantages such as high catalytic activity and selectivity, and mild reaction conditions. However, the accumulation of byproducts during the reaction leads to catalyst deactivation. When the catalyst's catalytic activity significantly decreases, regeneration is required, a cumbersome and complex process that necessitates intermittent shutdowns. Furthermore, the post-reaction products require oil-water separation, also necessitating intermittent shutdowns. These processes directly impact production efficiency and increase operating costs.
[0005] CN110698435A discloses a method for preparing epichlorohydrin, which uses a reaction bed as a reactor, allyl chloride and hydrogen peroxide as raw materials, methanol as a solvent, titanium silicate molecular sieve as a catalyst, and quaternary ammonium salt as a surfactant. Although this method extends the service life of the titanium silicate molecular sieve in the fixed bed, thereby extending the catalyst cycle and improving production efficiency, it still cannot avoid the problems of intermittent shutdowns required for catalyst regeneration and subsequent oil-water separation, resulting in wasted reactants and significant economic losses. Summary of the Invention
[0006] To overcome the shortcomings of the prior art, the present invention provides a method for continuous production of epichlorohydrin, which can ensure the stability of catalyst reaction performance and the continuous and stable operation of the production process, thereby reducing production costs and improving production efficiency.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A method for continuous production of epichlorohydrin includes the following steps:
[0009] 1) Mixing: Allyl chloride and methanol are fed into a mixer and mixed evenly to prepare a mixture;
[0010] 2) Preheating: Hydrogen peroxide and the mixture are fed into a preheater and preheated to a certain temperature;
[0011] 3) Epoxidation reaction: The preheated material is fed into a fixed-bed reactor to carry out the epoxidation reaction;
[0012] 4) Cooling the product: The product after the epoxidation reaction is sent to a cooler and cooled to a certain temperature;
[0013] 5) Distillation separation: The cooled product is fed into the first distillation column for distillation to separate allyl chloride and methanol from the product;
[0014] 6) Oil-water separation: The product from which allyl chloride and methanol are separated is sent to an oil-water separator for oil-water separation;
[0015] 7) Refined epichlorohydrin: The separated oil phase is sent to the second distillation column for distillation to obtain epichlorohydrin;
[0016] The fixed-bed reactor includes a first fixed-bed reactor and a second fixed-bed reactor connected in parallel. Step 3) specifically includes the following steps:
[0017] S1. The preheated material is fed into the first fixed-bed reactor for epoxidation reaction; the catalyst in the second fixed-bed reactor is regenerated.
[0018] S2. The preheated material is fed into the second fixed-bed reactor for epoxidation reaction; the catalyst in the first fixed-bed reactor is regenerated.
[0019] S3. Repeat steps S1 to S2.
[0020] The oil-water separator includes multiple oil-water separators connected in parallel. In step 6), before the oil-water separation is completed, the working oil-water separator sends the product to any of the other non-working oil-water separators connected in parallel to carry out the oil-water separation process continuously.
[0021] This invention employs a first fixed-bed reactor and a second fixed-bed reactor connected in parallel, enabling alternating epoxidation and catalyst regeneration operations. While the first fixed-bed reactor performs the epoxidation reaction, the second fixed-bed reactor regenerates the catalyst; conversely, while the first fixed-bed reactor regenerates the catalyst, the second fixed-bed reactor performs the epoxidation reaction. This alternating operation of the epoxidation reaction and catalyst regeneration in the first and second fixed-bed reactors ensures timely and effective catalyst regeneration, effectively avoiding the activity decline and intermittent production shutdowns caused by prolonged catalyst operation. This keeps the epoxidation catalyst in a consistently high-efficiency operating state, guaranteeing continuous, efficient, and high-quality epichlorohydrin production. Simultaneously, this invention utilizes multiple parallel oil-water separators, allowing for switching between them when intermittent shutdowns are required. This enhances the stability and reliability of equipment operation, ensuring continuous operation of the separation stage and meeting the requirements for continuous industrial production of epichlorohydrin.
[0022] In this invention, both the first fixed-bed reactor and the second fixed-bed reactor can be multiple fixed-bed reactors connected in series and / or in parallel. Preferably, the first fixed-bed reactor and the second fixed-bed reactor have the same reactor structure and number to ensure a stable and efficient reaction.
[0023] In this invention, the products of the epoxidation reaction include allyl chloride, methanol, epichlorohydrin, water, and byproducts. Unreacted allyl chloride and solvent methanol are separated sequentially by a first distillation column, water is separated by an oil-water separator, and byproducts are separated by a second distillation column, thereby obtaining high-purity epichlorohydrin.
[0024] Preferably, in step 1), the molar ratio of allyl chloride to methanol is 1:5 to 20, more preferably 1:10 to 15.
[0025] Preferably, in step 2), the hydrogen peroxide exists in the form of a hydrogen peroxide solution with a mass concentration of 30-50%.
[0026] Preferably, in step 2), the molar ratio of hydrogen peroxide to allyl chloride in the mixture is 1:0.5 to 5, more preferably 1:1 to 2.
[0027] Preferably, in step 2), the temperature is preheated to 30°C to 60°C, more preferably to 35°C to 45°C.
[0028] Preferably, in step 3), the temperature of the epoxidation reaction is 30℃~60℃, more preferably 35℃~45℃.
[0029] Preferably, in step 3), the space velocity of the epoxidation reaction is 0.2–50 h⁻¹. -1 More preferably 1 to 10 hours-1 .
[0030] Preferably, in step 3), the fixed-bed reactor is filled with a particulate catalyst of titanium-silicon molecular sieve;
[0031] More preferably, the particulate catalyst of the titanium-silicon molecular sieve has an MFI structure and a particle size of 0.1 mm to 10 mm, more preferably 1 to 3 mm.
[0032] Preferably, in step 4), the temperature is cooled to 10°C to 30°C, more preferably to 15°C to 25°C.
[0033] Preferably, step 5) further includes the following step: returning the separated allyl chloride and methanol to the mixer described in step 1) for reuse.
[0034] The beneficial effects of this invention are at least as follows:
[0035] The method for continuous production of epichlorohydrin provided by this invention employs a first fixed-bed reactor and a second fixed-bed reactor operating in parallel during the epoxidation reaction, alternating between epoxidation and catalyst regeneration. This solves the problem of needing to shut down for regeneration after catalyst deactivation. In the oil-water separation process, multiple oil-water separators are operated in parallel, eliminating the need for intermittent shutdowns during oil-water separation. This improves production efficiency and equipment utilization, making it suitable for continuous industrial production. Furthermore, this method ensures the stability of catalyst activity and offers advantages such as fewer byproducts, higher epichlorohydrin selectivity, and higher yield. Attached Figure Description
[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the prior art in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0037] Figure 1 This is a process flow diagram for the continuous production of epichlorohydrin according to the present invention. Detailed Implementation
[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0039] Example 1
[0040] A method for continuous production of epichlorohydrin, which can be partially referenced Figure 1 This includes the following steps:
[0041] 1) Mixing: Allyl chloride and methanol are fed into a mixer at a molar ratio of 1:12 and mixed evenly to prepare a mixture;
[0042] 2) Preheating: A 30% hydrogen peroxide solution and the mixture are fed into a preheater and preheated to 45°C; the molar ratio of hydrogen peroxide to allyl chloride is 1:1.5.
[0043] 3) Epoxidation reaction: The preheated material is fed into a fixed-bed reactor for epoxidation. The fixed-bed reactor is filled with particulate catalyst of titanium-silicon molecular sieve with MFI structure, and the particle size is 1.2 mm to 1.4 mm. The reaction temperature is controlled at 45℃ using constant-temperature circulating water, and the space velocity is 5 h⁻¹. -1 ;
[0044] 4) Cooling the product: The product after the epoxidation reaction is cooled to 25°C using a cooler;
[0045] 5) Distillation separation: The cooled product is sent to the first distillation column for distillation to separate low-boiling-point chloropropene and methanol, which are then returned to step 1) to continue participating in the reaction.
[0046] 6) Oil-water separation: The products from which allyl chloride and methanol are separated are sent to an oil-water separator for liquid-liquid phase separation; the separated aqueous phase is discharged as wastewater.
[0047] 7) Refined epichlorohydrin: The separated oil phase is sent to the second distillation column for distillation to obtain high-purity epichlorohydrin;
[0048] The fixed-bed reactor includes a first fixed-bed reactor and a second fixed-bed reactor connected in parallel. Step 3) specifically includes the following steps:
[0049] S1. The preheated material is fed into the first fixed-bed reactor for epoxidation reaction for 100 hours; the catalyst in the second fixed-bed reactor is regenerated, specifically by high-temperature calcination.
[0050] S2. The preheated material is fed into the second fixed-bed reactor for epoxidation reaction for 100 hours; the catalyst in the first fixed-bed reactor is regenerated.
[0051] S3. Repeat steps S1 to S2.
[0052] The oil-water separator includes multiple oil-water separators connected in parallel. In step 6), before the oil-water separation is completed, the working oil-water separator sends the product to any of the other non-working oil-water separators connected in parallel to carry out the oil-water separation process continuously.
[0053] The continuous production method of epichlorohydrin using Example 1 does not require intermittent shutdowns, while the catalyst maintains high activity, with few byproducts, and the selectivity of epichlorohydrin remains stable at 95% and the yield remains stable at 90%.
[0054] Comparative Example 1 (Comparison with conventional methods for producing epichlorohydrin)
[0055] Comparative Example 1 used a single fixed-bed reactor for the epoxidation reaction. After 100 hours of operation, the catalyst activity dropped significantly, resulting in a decrease in the selectivity of epichlorohydrin to below 90% and the yield to below 80%, requiring shutdown for catalyst regeneration.
[0056] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A process for the continuous production of epichlorohydrin, characterized in that, The method comprises the following steps: 1) mixing: sending chloropropene and methanol into a mixer to mix uniformly to prepare a mixed solution; 2) preheating: sending hydrogen peroxide and the mixed solution into a preheater to preheat to a certain temperature; 3) epoxidation reaction: sending the preheated materials into a fixed bed reactor to perform epoxidation reaction; 4) cooling: sending the product after epoxidation reaction into a cooler to cool to a certain temperature; 5) rectification separation: sending the cooled product into a first rectification tower to perform rectification, separating chloropropene and methanol from the product, and sending the separated chloropropene and methanol back to the mixer of step 1) for reuse; 6) oil-water separation: sending the product after separation of chloropropene and methanol into an oil-water separator to perform oil-water separation; 7) refining epichlorohydrin: sending the separated oil phase into a second rectification tower to perform rectification to obtain epichlorohydrin; The fixed bed reactor comprises a first fixed bed reactor and a second fixed bed reactor connected in parallel, and the step 3) specifically comprises the following steps: S1, sending the preheated materials into the first fixed bed reactor to perform epoxidation reaction; and regenerating the catalyst in the second fixed bed reactor; S2, sending the preheated materials into the second fixed bed reactor to perform epoxidation reaction; and regenerating the catalyst in the first fixed bed reactor; S3, repeating the steps S1 to S2; The oil-water separator comprises a plurality of oil-water separators connected in parallel, and in the step 6), the working oil-water separator sends the product to any other non-working oil-water separator connected in parallel before the oil-water separation is completed, so as to continuously perform the oil-water separation process.
2. The method of continuously producing epichlorohydrin according to claim 1, characterized by, In step 1), the molar ratio of chloropropene to methanol is 1:5-20.
3. The method of continuously producing epichlorohydrin according to claim 2, characterized by, In step 1), the molar ratio of chloropropene to methanol is 1:10-15.
4. The method of continuously producing epichlorohydrin according to claim 1, characterized by, In step 2), the hydrogen peroxide exists in the form of hydrogen peroxide solution with a mass concentration of 30-50%.
5. The method of continuously producing epichlorohydrin according to claim 4, characterized by, In step 2), the molar ratio of hydrogen peroxide to chloropropene in the mixed solution is 1:0.5-5.
6. The method of continuously producing epichlorohydrin according to claim 5, characterized by, In step 2), the molar ratio of hydrogen peroxide to chloropropene in the mixed solution is 1:1-2.
7. The method of continuously producing epichlorohydrin according to claim 1, characterized by, In step 2), the preheating is to 30-60℃.
8. The method of continuously producing epichlorohydrin according to claim 7, characterized by, In step 2), the preheating is to 35-45℃.
9. The method of continuously producing epichlorohydrin according to claim 1, characterized by, In step 3), the temperature of the epoxidation reaction is 30-60℃.
10. The method of continuously producing epichlorohydrin according to claim 9, characterized by, In step 3), the temperature of the epoxidation reaction is 35-45℃.
11. The method of continuously producing epichlorohydrin according to claim 10, characterized by, In step 3), the fixed bed reactor is filled with titanium silicalite molecular sieve granular catalyst.
12. The method of continuously producing epichlorohydrin according to claim 11, characterized by, In step 3), the titanium silicalite molecular sieve granular catalyst has MFI structure and a particle size of 0.1-10mm.
13. The method of continuously producing epichlorohydrin according to claim 12, characterized by, In step 3), the titanium silicalite molecular sieve granular catalyst has a particle size of 1-3mm.
14. The method of continuously producing epichlorohydrin according to claim 1, characterized by, In step 4), the cooling is to 10-30℃.
15. The method of continuously producing epichlorohydrin according to claim 14, characterized by, In step 4), the cooling is to 15-25℃.
Citation Information
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