Slag-reducing environment-friendly epoxypropane saponification reaction method

Abstract

The invention relates to a residue-reducing and environment-friendly epoxypropane saponification reaction method. The method comprises the following steps: carrying out epoxidation on chlorohydrin in the presence of alkali to obtain epoxypropane; wherein the average particle size D of the alkali is smaller than or equal to 1000 microns. According to the method, the saponification reaction efficiency and the epoxypropane production efficiency are remarkably improved, the dosage of calcium hydroxide and the solid waste yield can be remarkably reduced, and remarkable economic advantages and environmental protection advantages are achieved.

Description

Technical Field

[0001] The present invention relates to a method for saponification reaction of propylene oxide with reduced residue and environmental protection, belonging to the field of energy-saving and environmental-friendly chemical processes. Background Art

[0002] Among numerous chemical products, propylene derivatives occupy an important position. Among these derivatives, the production of propylene oxide (PO) is particularly prominent, second only to polypropylene and acrylonitrile, and becomes one of the important varieties of propylene derivatives. As an important organic chemical raw material, propylene oxide is widely used in the production processes of various chemical products such as polyurethane, surfactants, and propylene glycol. Its large market demand and wide application fields make propylene oxide play a crucial role in the global chemical industry. With the continuous progress of chemical technology and the continuous growth of market demand, the production and application prospects of propylene oxide will continue to maintain a strong development momentum.

[0003] Currently, the industrial methods for synthesizing propylene oxide mainly include the chlorohydrin method, ethylbenzene co-oxidation method, isobutane co-oxidation method, hydrogen peroxide direct oxidation method (HPPO), etc. Among them, the chlorohydrin method is a relatively mature process. It generates chlorohydrin by chlorinating propylene and then obtains propylene oxide by dehydrochlorination. However, this method will produce a large amount of waste residue, causing environmental pollution. The ethylbenzene co-oxidation method generates propylene oxide by co-oxidizing ethylbenzene and oxygen. Although this method reduces the generation of waste residue, it has high energy consumption, and the toxicity of ethylbenzene also poses a threat to the environment and the health of operators. The isobutane co-oxidation method uses isobutane and oxygen to generate propylene oxide under the action of a catalyst. This method has more by-products and requires a high purity of the raw material isobutane. The hydrogen peroxide direct oxidation method directly reacts hydrogen peroxide and propylene to generate propylene oxide. The by-product of this method is only water, which is an environmentally friendly production method. However, the current technology is not yet mature and the cost is relatively high.

[0004] The present invention aims to provide a lime milk for propylene oxide production and its use to improve the efficiency of the saponification reaction in propylene oxide production. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for saponification reaction, which includes: epoxidizing chlorohydrin in the presence of a base to obtain propylene oxide; wherein, the average particle size D of the base ≤ 1000 μm.

[0006] According to an embodiment of the present invention, the average particle size D of the base is selected from 10 to 1000 μm, such as 15 to 500 μm, for example 20 to 250 μm, 25 to 200 μm, 30 to 150 μm, 40 to 100 μm. As an example, D can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 150 μm or 200 μm.

[0007] According to an embodiment of the present invention, the base may include inorganic bases known in the art that can be used for saponification reactions, and it may be selected from one or more of including but not limited to Ca(OH)2, CaCO3, CaO, Mg(OH)2, MgCO3, NaOH, Na2CO3, NaHCO3.

[0008] Preferably, the average particle size D of the Ca(OH)2 or CaO is selected from 10 to 1000 μm, such as 15 to 500 μm, for example 20 to 250 μm, 25 to 200 μm, 30 to 150 μm, 40 to 100 μm. As an example, D can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 150 μm or 200 μm.

[0009] According to an embodiment of the present invention, the purity of the base (such as Ca(OH)2 or CaO) is not less than 90%, for example 90 to 95%.

[0010] According to an embodiment of the present invention, the base reacts with the chlorohydrin in the form of its mixture with water. For example, a mixture of Ca(OH)2 or CaO and water reacts with the chlorohydrin. In some embodiments, the water is provided by the following concentrated solution.

[0011] According to an embodiment of the present invention, the chlorohydrin can be monochloropropanol, which is selected from 1-chloro-2-propanol, 2-chloro-1-propanol or a mixture thereof.

[0012] According to an embodiment of the present invention, the chlorohydrin can react with the base in the form of the product of the propylene chlorohydrination reaction.

[0013] According to an embodiment of the present invention, the temperature of the saponification reaction (i.e., the kettle temperature) range can be 80 to 95 °C, such as 85 to 86 °C.

[0014] According to an embodiment of the present invention, in the saponification reaction, when 1 mole of the base (such as Ca(OH)2, CaCO3, CaO, Mg(OH)2, MgCO3, Na2CO3) can react with 2 moles of H + in the reaction, the molar ratio range of the base to the chlorohydrin can be 1.05 to 1.20. Alternatively, when 1 mole of the base (such as NaOH, NaHCO3) can react with 1 mole of H + in the reaction, the molar ratio range of the base to the chlorohydrin can be 2.10 to 2.40.

[0015] The present invention also provides a mixture, which comprises a mixture of the base and water as described above. Among them, in the mixture, the concentration of the base can be 5% to 10 wt% (calculated as OH - ). In some embodiments, the water is provided by the following concentrated solution.

[0016] The present invention also provides a method for producing propylene oxide, which includes the method of the above saponification reaction.

[0017] According to an embodiment of the present invention, the method for producing propylene oxide further includes an allyl chlorohydrin reaction, in which the product of the allyl chlorohydrin reaction is subjected to a saponification reaction with the base to obtain propylene oxide.

[0018] According to an embodiment of the present invention, the method for producing propylene oxide includes:

[0019] The chloropropanol undergoes a saponification reaction in the system to obtain propylene oxide;

[0020] The system includes lime milk, chlorohydrin solution, concentrated solution, and the reaction material of the concentrated solution and chlorohydrin;

[0021] The concentrated solution is obtained by concentrating the saponification residue generated by the saponification reaction. For example, the concentration is carried out by means such as sedimentation or centrifugation.

[0022] According to an embodiment of the present invention, the concentration ratio of the saponification residue to the concentrated solution is 1:1.05 to 1:8, such as 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7.

[0023] According to an embodiment of the present invention, the chlorohydrin solution is the reaction solution after the chlorohydrin reaction of the reaction product of propylene with chlorine and water.

[0024] According to an embodiment of the present invention, the concentrated solution (i.e., the concentrated saponification residue) accounts for 70% to 99% of the total volume of the saponification residue, such as 75%, 80%, 85%, 90%, 92%, 95%.

[0025] According to an embodiment of the present invention, a partial saponification residue solution generated by the saponification reaction is acidified to neutralize calcium hydroxide therein. For example, hydrochloric acid is added, and the amount of hydrochloric acid is such that it only reacts with calcium hydroxide and does not react with calcium carbonate. Preferably, the pH value after mixing and reacting the saponification residue solution with hydrochloric acid is 8.6 to 9.6 to avoid the emission of greenhouse gas CO2.

[0026] According to an embodiment of the present invention, the flow rate ratio of the acidified saponification residue solution to the saponification residue solution separated by sedimentation is 1:3 to 1:8, such as 1:4, 1:5, 1:6, 1:7.

[0027] According to some embodiments of the present invention, the content of calcium hydroxide in the saponification residue solution is 0.1 to 0.2%, and the content of calcium carbonate is 0.2 to 0.5%; and / or, the content of calcium hydroxide in the concentrated solution is 0.5 to 1.5%, and the content of calcium carbonate is 1 to 5%.

[0028] According to an embodiment of the present invention, the solid particles in the saponification residue solution may include one, two or more selected from oxides, hydroxides, carbonates or hydrochloric acid-insoluble substances of metal or non-metal elements.

[0029] According to an embodiment of the present invention, the metal or non-metal element may be selected from one, two or more of Ca, Mg, Fe, Al, Si.

[0030] According to an embodiment of the present invention, the solid particles in the saponification residue solution may include one, two or more selected from Ca(OH)2, CaCO3, MgCO3, Fe2O3, Al2O3, SiO2. For example, the filter residue may include Ca(OH)2, CaCO3, Mg(OH)2, MgCO3, Fe2O3, Al2O3 and SiO2.

[0031] According to an embodiment of the present invention, the solid particles in the saponification residue solution may also include CaSO4.

[0032] According to an embodiment of the present invention, in the concentration process, the ratio of the recycled amount of the concentrated solution to the overflow amount of the supernatant can be 1:3 to 1:10, such as 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0033] According to an embodiment of the present invention, the molar ratio of Ca(OH)2 to chloropropanol is higher than 1:1 and lower than 1.5:1, for example (1.05 - 1.3):1, such as 1.05:1, 1.10:1, 1.15:1, 1.20:1, 1.25:1 or 1.30:1.

[0034] According to an embodiment of the present invention, the flow rate ratio of the concentrated liquid to the chlorohydrin liquid can be 1:5 to 1:20, such as 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20.

[0035] According to an embodiment of the present invention, the method for producing propylene oxide further includes: subjecting the saponification residue after acidification treatment to solid-liquid separation and feeding it into industrial water treatment and waste residue treatment.

[0036] According to an embodiment of the present invention, the method for producing propylene oxide further includes: sending other concentrated liquids (concentrated liquids other than those used for preparing lime milk, reacting with chlorohydrin, and returning to the system) and / or the supernatant of the concentrated pool to industrial water treatment.

[0037] Beneficial effects

[0038] The method of the present invention significantly improves the saponification reaction and the production efficiency of propylene oxide, and can significantly reduce the dosage of calcium hydroxide and the solid waste output, having significant economic advantages and environmental protection advantages. Specific embodiments

[0039] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only for illustrative and explanatory purposes of the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0040] Example 1: Preparation of lime milk

[0041] In the lime milk preparation device, Ca(OH)2 / CaO with a purity of 92% in the same batch was screened and ground to obtain samples 1-5 with different average particle sizes as follows.

[0042] Samples 1-5 were respectively added to the lime milk preparation device in an amount corresponding to 0.2% of the Ca(OH)2 content in the saponification residue generated by the saponification reaction and mixed with the concentrated liquid to obtain lime milk. Among them, the concentrated liquid was obtained by concentrating the saponification residue, with a concentration ratio of 1:6. The composition of the concentrated liquid was: calcium hydroxide 0.7%, calcium carbonate 2.6%; the mass percentage concentration of Ca(OH)2 in the lime milk was 7 wt%, calculated as OH - respectively. The following lime milk samples were obtained:

[0043]

[0044]

[0045] Example 2: Saponification reaction experiment

[0046] In the saponification tower, the chlorohydrin solution (addition amount A) and the lime milk sample of Example 1 (addition amount B) are added into the saponification reaction device through the feed inlet, and the kettle temperature of the saponification reaction device is controlled to be 85-86 °C for the saponification reaction to prepare propylene oxide. The saponification kettle temperature is Tf, and the top temperature is Td.

[0047] Among them, the chlorohydrin solution contains 4.05 wt% chlorohydrin, 1.68 wt% HCl, and the balance is water. The chlorohydrin is a mixture of 1-chloro-2-propanol and 2-chloro-1-propanol.

[0048]

[0049] In summary, the production device of the present invention improves the saponification reaction and the production efficiency of propylene oxide, and can significantly reduce the consumption of alkali and the output of solid waste, having significant economic and environmental advantages.

[0050] The above has given an exemplary description of the implementation manner of the technical solution of the present invention. It should be understood that the protection scope of the present invention is not limited to the above implementation manner. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the claims of this application.

Claims

1. A method for saponification reaction, characterized in that, The method includes: epoxidation of chlorohydrin in the presence of a base to obtain propylene oxide; wherein, the average particle size D of the base ≤ 1000 μm.

2. The method according to claim 1, wherein The average particle size D of the base is selected from 10 - 1000 μm; and / or, the base is selected from one or more of, including but not limited to, Ca(OH)2, CaCO3, CaO, Mg(OH)2, MgCO3, NaOH, Na2CO3, NaHCO3; and / or, the purity of the base is not less than 90%.

3. The method according to claim 1, characterized in that The base is Ca(OH)2 or CaO, and the average particle size D is selected from 10 - 1000 μm.

4. The method according to claim 1, wherein The base reacts with chlorohydrin in the form of its mixture with water; For example, the water is provided by a concentrated solution, and the concentrated solution is obtained by concentrating the saponification residue produced by the saponification reaction.

5. The method according to claim 1, wherein The temperature range of the saponification reaction is 80 - 95 °C; And / or, in the saponification reaction, when 1 mole of the base can react with 2 moles of H + the molar ratio of the base to the chlorohydrin ranges from 1.05 to 1.20; or when 1 mole of the base can react with 1 mole of H + the molar ratio of the base to the chlorohydrin ranges from 2.10 to 2.

40.

6. A production method of propylene oxide, characterized in that, The production method includes the saponification reaction method described in any one of claims 1 - 5.

7. The production method according to claim 6, characterized in that, The production method of the propylene oxide further includes an allyl chlorohydrin reaction, wherein the product of the allyl chlorohydrin reaction is subjected to a saponification reaction with the base to obtain propylene oxide.

8. The production method according to claim 6, characterized in that, The production method of the propylene oxide includes: chloropropanol undergoes a saponification reaction in the system to obtain propylene oxide; The system includes lime milk, chlorohydrin solution, concentrated solution, and the reaction material of the concentrated solution and chlorohydrin; The concentrated solution is obtained by concentrating the saponification residue produced by the saponification reaction; The chlorohydrin solution is the reaction solution after the chlorohydrin reaction of the reaction product of propylene with chlorine and water.

9. The production method according to any one of claims 6 - 8, characterized in that, Part of the saponification residue produced by the saponification reaction is acidified to neutralize the calcium hydroxide therein; Preferably, the production method of the propylene oxide further includes: the acidified saponification residue is subjected to solid-liquid separation and sent for industrial water treatment and waste residue treatment.

10. The production method according to claim 8, characterized in that The calcium hydroxide content in the saponification residue is 0.1 - 0.2%, and the calcium carbonate content is 0.2 - 0.5%; and / or, the calcium hydroxide content in the concentrated solution is 0.5 - 1.5%, and the calcium carbonate content is 1 - 5%; Furthermore, the solid particles in the saponification residue further include one, two or more selected from oxides, hydroxides, carbonates or hydrochloric acid-insoluble substances of metal or non-metal elements.

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