CN114249704B - Preparation method of alkylene oxide - Google Patents
Preparation method of alkylene oxide Download PDFInfo
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- CN114249704B CN114249704B CN202011018033.0A CN202011018033A CN114249704B CN 114249704 B CN114249704 B CN 114249704B CN 202011018033 A CN202011018033 A CN 202011018033A CN 114249704 B CN114249704 B CN 114249704B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
- C07D303/02—Compounds containing oxirane rings
- C07D303/04—Compounds containing oxirane rings containing only hydrogen and carbon atoms in addition to the ring oxygen atoms
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D301/00—Preparation of oxiranes
- C07D301/02—Synthesis of the oxirane ring
- C07D301/24—Synthesis of the oxirane ring by splitting off HAL—Y from compounds containing the radical HAL—C—C—OY
- C07D301/26—Y being hydrogen
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- C—CHEMISTRY; METALLURGY
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- C07D301/00—Preparation of oxiranes
- C07D301/32—Separation; Purification
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Abstract
The invention discloses a preparation method of alkylene oxide. The preparation method comprises the following steps: the aqueous solution of chlorohydrin containing high-concentration metal chloride is contacted with alkali for saponification reaction to obtain crude alkylene oxide and saponification waste liquid; the concentration of the metal chloride in the chlorohydrin aqueous solution is not less than 10wt%. The preparation method of the alkylene oxide provided by the invention can reduce or even not generate waste water, and realize green production of the alkylene oxide by a chlorohydrination method.
Description
Technical Field
The invention belongs to the field of preparation of alkylene oxide, and particularly relates to a preparation method of alkylene oxide.
Background
Alkylene oxide is an important organic chemical, is mainly used for preparing dihydric alcohol and polyether, and has wide application in industries such as petroleum, chemical industry, pesticide, textile, daily chemicals and the like. The production and preparation method of the alkylene oxide mainly comprises a chlorohydrination method, a co-oxidation method and a direct oxidation method, wherein the chlorohydrination method has the advantages of low investment, mild reaction, high production safety, more mature process, short flow and the like. The chlorohydrination method of propylene oxide, for example, includes: the chlorine and the propylene react to generate a chloropropanol aqueous solution, the chloropropanol aqueous solution and the calcium hydroxide react with saponification to obtain epoxypropane, and the main reaction and the side reaction are as follows:
chlorohydrination main reaction:
chlorohydrination side reaction:
saponification main reaction:
saponification side reaction:
however, the chlorohydrination method has the disadvantages of large wastewater amount, serious environmental pollution, and the like. Especially, the large amount of salt-containing wastewater becomes the biggest obstacle for development of a chlorohydrination method, for example, in the existing chlorohydrination method propylene oxide production device, chlorohydrination reaction liquid containing 3-5wt% of chloropropanol and calcium hydroxide aqueous emulsion with the concentration of 17wt% are sent into a saponification tower to carry out saponification reaction, water vapor which is directly introduced into the saponification tower provides heat and steam out of a reaction product propylene oxide, crude propylene oxide obtained at the top of the saponification tower is further rectified and separated to prepare propylene oxide, saponification waste liquid containing about 3wt% of calcium chloride is obtained at the tower bottom, and waste water containing about 3wt% of salt is produced as a byproduct per ton of product 45-50t. In view of the shortcomings of the method, industrial production methods of alkylene oxide such as a co-oxidation method and a direct oxidation method are developed, and the problems of salt-containing wastewater are solved by the methods, but the co-oxidation method and the direct oxidation method have the defects of a plurality of reaction byproducts, complex post-treatment and the like due to the introduction of strong oxidation reaction, and cannot completely replace a chlorohydrination method, so that most half-wall Jiangshan still occupied by using the chlorohydrination method in the existing alkylene oxide production device and process. Along with the increasing environmental protection pressure, how to develop the advantages of the chlorohydrination method and reduce or even eliminate the wastewater discharge generated by the process is an important subject in the alkylene oxide preparation industry.
Disclosure of Invention
The invention provides a preparation method of alkylene oxide, which comprises the following steps: the method comprises the steps of (1) contacting a chlorohydrin aqueous solution containing metal chloride with alkali for saponification reaction to obtain crude alkylene oxide and saponification waste liquid;
the concentration of the metal chloride in the chlorohydrin aqueous solution is not less than 10wt%.
According to an embodiment of the present invention, the concentration of the metal chloride in the aqueous chlorohydrin solution is 10 to 50wt%, more preferably 20 to 35wt%, and exemplified by 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 50wt%.
According to an embodiment of the present invention, the metal in the metal chloride is at least one of a group I element, a group II element, preferably sodium and/or calcium. Preferably, the metal chloride is sodium chloride and/or calcium chloride.
According to an embodiment of the present invention, the aqueous chlorohydrin solution containing a metal chloride is obtained by reacting chlorine gas and an olefin in a high concentration aqueous metal chloride solution. Specifically, the content of the metal chloride in the high-concentration metal chloride aqueous solution is greater than or equal to 10wt%, preferably the concentration is 10 to 50wt%, further preferably 20 to 35wt%, and exemplary is 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, or any point value between any two combinations of the above.
Wherein the olefin is ethylene, propylene, chloropropene or butylene, etc.
According to an embodiment of the present invention, the chlorohydrin content of the aqueous chlorohydrin solution is 1 to 10wt%, preferably 2 to 5wt%, and exemplified by 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 8wt%, 10wt%.
According to an embodiment of the invention, the molar ratio of chlorine to olefin is 1 (1.01-1.3), for example 1 (1.05-1.175), and for example 1 (1.1-1.15).
According to an embodiment of the present invention, the temperature of the reaction for preparing the aqueous chlorohydrin solution is 10 to 80 ℃, for example 20 to 70 ℃, and is exemplified by 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃.
According to an embodiment of the present invention, the pressure of the reaction for preparing the aqueous chlorohydrin solution is 0.1 to 0.5MPa, for example 0.2 to 0.4MPa, and exemplary is 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa.
According to an embodiment of the present invention, the preparation process of the aqueous chlorohydrin solution may be performed in a chlorohydrination reaction device known in the art.
According to an embodiment of the present invention, the saponification reaction is carried out at a temperature of 30-130 ℃, for example 50-100 ℃, illustratively 50 ℃, 60 ℃, 70 ℃, 75 ℃, 80 ℃, 90 ℃, 100 ℃.
According to an embodiment of the invention, the saponification reaction is carried out at a pressure of 0.02-0.5MPa, for example 0.05-0.4MPa, exemplary 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa.
According to an embodiment of the invention, the molar ratio of chlorohydrin to base is 1 (1.01-3.0), for example, the molar ratio of chlorohydrin to calcium hydroxide is 1 (1.1-1.4), and for example, the molar ratio of chlorohydrin to calcium hydroxide is 1 (1.15-1.3), and for example, the molar ratio of chlorohydrin to calcium hydroxide is 1:1.2.
According to an embodiment of the invention, the base is added in the form of an aqueous base solution or an aqueous base emulsion. For example, the concentration of the alkali in the aqueous alkali solution or alkali aqueous emulsion is 10 to 40% by weight, preferably 15 to 35% by weight.
According to an embodiment of the present invention, the base refers to at least one of a hydroxide of a group I element, a hydroxide of a group II element, and a carbonate of a group I element, preferably at least one of calcium hydroxide, sodium hydroxide, and sodium carbonate.
According to an embodiment of the present invention, the preparation method further comprises: after pretreatment, one part of the saponification waste liquid returns to the chlorohydrination reaction step (for example, replaces process water to return to the chlorohydrination reaction and/or prepares aqueous solution of alkali or aqueous emulsion of alkali used in the saponification reaction), and the other part of the saponification waste liquid is evaporated, concentrated, cooled, crystallized or dried to obtain the solid of the metal chloride.
According to an embodiment of the invention, the pretreatment comprises at least one of filtration, neutralization and cooling.
According to an embodiment of the invention, the drying is spray drying.
According to an embodiment of the invention, the evaporation is multiple effect evaporation.
According to an embodiment of the invention, the saponification reaction is carried out in a saponification column.
According to an embodiment of the present invention, the saponified solution is subjected to evaporation concentration, the water vapor obtained by the evaporation concentration is used as a heat source for the saponification column, and/or the water vapor obtained by the evaporation concentration is used as a heat source for a reboiler of the separation column for crude alkylene oxide.
According to an embodiment of the invention, the separation after the cooling crystallization is accomplished by filtration or centrifugation.
According to an embodiment of the invention, the crude alkylene oxide is separated by distillation to obtain an alkylene oxide product.
According to an exemplary embodiment of the present invention, the method for preparing alkylene oxide includes the steps of:
the aqueous solution of chlorohydrin containing metal chloride with concentration not less than 10wt% is contacted with alkali for saponification reaction, and crude alkylene oxide and saponification waste liquid are obtained; after pretreatment, one part of the saponification waste liquid returns to the chlorohydrination reaction step, and the other part of the saponification waste liquid is subjected to evaporation concentration, cooling crystallization or drying to obtain the solid of the metal chloride;
the water vapor obtained by evaporating and concentrating the saponified solution is used as a heat source of a saponification tower, and/or the water vapor obtained by evaporating and concentrating is used as a heat source of a reboiler of a separation tower of crude alkylene oxide;
and (3) rectifying and separating the crude alkylene oxide to obtain an alkylene oxide product.
The beneficial effects of the invention are that
The aqueous solution of chlorohydrin containing more than 10wt% of metal chloride is sent into a saponification tower to contact with alkali for saponification, crude alkylene oxide is obtained at the top of the saponification tower, saponified waste liquid containing high-concentration metal chloride is obtained at the bottom of the saponification tower, the saponified waste liquid is concentrated to obtain metal chloride concentrated solution and water vapor, the metal chloride obtained by further crystallizing and separating the metal chloride concentrated solution can be sold as commodity, and the water vapor is used as a heat source of the saponification tower and/or the crude alkylene oxide separation tower. The preparation method of the alkylene oxide provided by the invention can reduce or even not generate waste water, and realize green production of the alkylene oxide by a chlorohydrination method.
Drawings
FIG. 1 is a process flow diagram of a method for preparing alkylene oxide of example 3.
Reference numerals: 1. process water, 2, chlorine, 3, propylene, 4, chlorohydrination reaction liquid, 5, epoxypropane, 6, steam, 7, saponification waste liquid, 8, pretreatment saponification waste liquid, 9, saponification waste liquid for preparing lime milk, 10, solid calcium hydroxide, 11, lime milk, 12, saponification waste liquid returned to a chlorohydrination reactor, 13, evaporation-concentration saponification waste liquid, 14, calcium chloride solid, 15, evaporation steam, 16, saponification steam, 17 and recovered steam used as a heat source of a crude epoxypropane rectification separation tower.
Detailed Description
The technical scheme of the invention will be further described in detail below with reference to specific embodiments. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention. All techniques implemented based on the above description of the invention are intended to be included within the scope of the invention.
Unless otherwise indicated, the starting materials and reagents used in the following examples were either commercially available or may be prepared by known methods.
The analysis conditions for the products in the examples below were as follows:
analytical instrument: agilent GC7820; chromatographic column: 30 m.times.530 μm.times.0.25 μm DB-FFAP; a detector: FID; sample inlet temperature: 225 ℃, detector temperature: 240 ℃, programming to raise the temperature: maintaining at 40deg.C for 5min,30 deg.C/min to 230deg.C for 5min; h 2 ：0.1Mpa，AIR：0.1Mpa；N 2 :0.075Mpa; tail blowing: 0.1Mpa.
Example 1
Chlorohydrination reaction
The reaction device is a 1000ml four-port round bottom glass flask with mechanical stirring at 100rpm, two bottom inserting pipes are arranged at two bottle openings, one for introducing chlorine and the other for introducing propylene. The reaction solution contains 20wt% of calcium chloride solution, the total volume of the reaction solution is 800ml, the reaction temperature is controlled to be 50 ℃ by a hot water bath, and the reaction flask is wrapped with black plastic cloth and protected from light.
Chlorine gas was introduced under the liquid surface of the reaction flask at a rate of 52ml/min (2.3 mmol/min), and propylene was introduced under the liquid surface of the reaction flask at a rate of 62ml/min (2.7 mmol/h).
The gas phase is removed from the gas phase space of the reaction bottle and is absorbed by alkali liquor and ethyl acetate in two stages.
The contents of chloropropanol and impurities in the reaction materials are analyzed, and the contents of propylene and impurities in the removed gas phase of the reaction bottle are analyzed.
Comprehensive analysis results after 200min of aeration reaction: 3.02wt% of chloropropanol (PCH), 0.14wt% of Dichloropropane (DCP), 0.08wt% of dichlorodiisopropyl ether (PCE), 0.010wt% of chloroacetone and 19.4wt% of calcium chloride.
Saponification reaction
823g of chlorohydrination reaction liquid (containing 263mmol of PCH), 137.5g of 17wt% calcium hydroxide aqueous emulsion (315.5 mmol) are mixed and added into a reaction bottle, the reaction temperature is controlled to be 75 ℃, stripping nitrogen is introduced below the reaction liquid level at a speed of 100L/min, and the obtained gas phase reaction product, namely crude propylene oxide, is cooled by cold water at 5 ℃, and tail gas is absorbed and trapped by 2000ml of methyl acetate at-25 ℃. The reaction solution was monitored by analysis, and when the chloropropanol content in the saponified solution was less than 0.01wt%, the reaction was ended.
The saponification waste liquid in the reaction bottle is filtered, and 2.50g of wet slag is filtered, so that 925g of pale yellow saponification waste liquid is obtained, the pH value is 12-13, and the saponification waste liquid contains 20.3wt% of calcium chloride and 0.022wt% of propylene glycol. The yield of propylene oxide was 98.5%.
Example 2
Chlorohydrination reaction
The operation parameters and the feeding amount were the same as those in example 1 except that the saponification waste liquid of example 1 was used as the reaction liquid.
After 205min of aeration, the mass fraction of chloropropanol in the reaction solution reached about 3.1wt%, and the reaction solution was pale yellow in appearance.
The analysis results showed that the chloropropanol content in the reaction solution was 3.1wt%, the DCP content was 0.16wt%, the PCE content was 0.083wt%, the chloroacetone content was 0.013wt%, and the calcium chloride content was 19.6wt%.
Saponification reaction
823g of chlorohydrination reaction liquid (containing 270mmol of PCH), 141g of 17wt% calcium hydroxide aqueous emulsion (324 mmol) are mixed and added into a reaction bottle, the reaction temperature is controlled to be 75 ℃, stripping nitrogen is introduced below the reaction liquid level at a speed of 100L/min, the obtained reaction product gas phase-crude epoxypropane is cooled by cold water at 5 ℃, and tail gas is absorbed and trapped by 2000ml of methyl acetate at-25 ℃. The reaction solution was monitored by analysis, and when the chloropropanol content in the saponified solution was less than 0.01wt%, the reaction was ended.
After the reaction, the saponification liquid was filtered to remove 2.45g of wet slag, and 930g of pale yellow saponification waste liquid was obtained, the pH value was 12-13, and the saponification liquid contained 20.4wt% of calcium chloride and 0.020wt% of propylene glycol. The yield of propylene oxide was 98.5%.
Example 3
As shown in the preparation process flow chart of the epoxypropane in figure 1, process water 1 and/or saponification waste liquid 12 returned to a chlorohydrination reactor are added into the chlorohydrination reactor, chlorine 2 and propylene 3 are introduced to obtain chlorohydrination reaction liquid 4 with the concentration of 2-5wt% of chloropropanol, the chlorohydrination reaction liquid 4 enters the saponification reactor and lime milk 11 for saponification reaction, and the lime milk 11 is prepared from solid calcium hydroxide 10 and saponification waste liquid 9 and/or process water mixture for preparing lime milk. The heat of saponification reaction is provided by steam 6 and/or recovered steam 16 generated by evaporation concentration, propylene oxide 5 and saponification waste liquid 7 are generated by saponification, the saponification waste liquid 7 is pretreated to obtain pretreated saponification waste liquid, and the pretreated saponification waste liquid is divided into recycled saponification waste liquid 8 and evaporation concentration-removed saponification waste liquid 13. The saponification waste liquid 13 from which the evaporation and concentration are carried out is evaporated and concentrated to obtain a calcium chloride concentrated solution and evaporation steam 15, the calcium chloride concentrated solution is subjected to post-treatment such as cooling crystallization and the like to obtain solid calcium chloride 14, and the evaporation steam 15 can be used as steam 16 for saponification reaction and/or recovered steam 17 used as a heat source of a crude epoxypropane rectification separation tower.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (20)
1. A process for the preparation of an alkylene oxide, characterized in that the process comprises the steps of:
reacting chlorine and olefin in a metal chloride aqueous solution to obtain a chlorohydrin aqueous solution containing metal chloride; the concentration of the metal chloride in the chlorohydrin aqueous solution is not less than 10wt%; the content of chlorohydrin in the chlorohydrin aqueous solution is 1-10wt%; the metal chloride is calcium chloride; the olefin is propylene;
and (3) contacting the chlorohydrin aqueous solution containing the metal chloride with alkali to carry out saponification reaction to obtain crude alkylene oxide and saponification waste liquid.
2. The method of claim 1, wherein the concentration of the metal chloride in the aqueous chlorohydrin solution is 10-50wt%.
3. The method of claim 2, wherein the concentration of the metal chloride in the aqueous chlorohydrin solution is 20-35wt%.
4. A production method according to any one of claims 1 to 3, characterized in that the chlorohydrin content in the chlorohydrin aqueous solution is 2 to 5wt%.
5. A process according to any one of claims 1 to 3, wherein the molar ratio of chlorine to olefin is 1 (1.01 to 1.3).
6. The process of claim 5 wherein the molar ratio of chlorine to olefin is 1 (1.05-1.175).
7. A process according to any one of claims 1 to 3, wherein the temperature of the reaction for preparing the aqueous chlorohydrin solution is 10 to 80 ℃; and/or the pressure of the reaction for preparing the chlorohydrin aqueous solution is 0.1-0.5MPa.
8. The method according to claim 7, wherein the temperature of the reaction for preparing the aqueous chlorohydrin solution is 20 to 70 ℃;
and/or the pressure of the reaction for preparing the chlorohydrin aqueous solution is 0.2-0.4MPa.
9. A method of preparation according to any one of claims 1 to 3, wherein the saponification reaction is carried out at a temperature of 30 to 130 ℃;
and/or the saponification reaction pressure is 0.02-0.5MPa;
and/or the molar ratio of chlorohydrin to alkali is 1 (1.01-3.0).
10. The method of claim 9, wherein the saponification reaction temperature is 50-100 ℃;
and/or the saponification reaction pressure is 0.05-0.4MPa.
11. The method according to claim 9, wherein the base is selected from the group consisting of calcium hydroxide, chlorohydrin and calcium hydroxide in a molar ratio of 1 (1.1-1.4).
12. A process according to any one of claims 1 to 3, wherein the base is added as an aqueous base solution or an aqueous base emulsion.
13. The method of claim 12, wherein the concentration of the base in the aqueous base solution or aqueous base emulsion is 10-40wt%.
14. The production method according to claim 13, wherein the base means at least one of a hydroxide of a group I element, a hydroxide of a group II element, and a carbonate of a group I element.
15. The method of claim 14, wherein the base is at least one of calcium hydroxide, sodium hydroxide, and sodium carbonate.
16. A method of preparation according to any one of claims 1 to 3, further comprising: and (3) after pretreatment, one part of the saponification waste liquid returns to the chlorohydrination reaction step, and the other part of the saponification waste liquid is subjected to evaporation concentration, cooling crystallization and/or drying to obtain the solid of the metal chloride.
17. The method of claim 16, wherein the pretreatment comprises at least one of filtration, neutralization, and cooling.
18. The method of preparation of claim 16, wherein the drying is spray drying;
and/or, the evaporation is multi-effect evaporation.
19. A production method according to any one of claims 1 to 3, wherein the saponification reaction is performed in a saponification column.
20. A process according to any one of claims 1 to 3, wherein the crude alkylene oxide is separated by distillation to give the alkylene oxide product.
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