A method for concentrating ethylene glycol aqueous solution

Abstract

The present invention provides a method for concentrating an ethylene glycol aqueous solution, comprising the following steps: S1, modifying a cationic resin with metal ions to obtain a modified cationic resin; S2, passing the ethylene glycol aqueous solution and excess butyraldehyde through a packed tower filled with the modified cationic resin to react for a period of time; wherein the butyraldehyde serves as both a reactant and an extractant; S3, after the reaction period, performing static separation, hydrolyzing the extract phase at a certain temperature using the modified cationic resin as a catalyst, and then recovering the butyraldehyde by distillation to obtain a concentrated ethylene glycol aqueous solution. The present invention has the advantages of low energy consumption and no wastewater.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a method for concentrating an ethylene glycol aqueous solution. Background Art

[0002] In order to improve the selectivity during the hydration reaction of ethylene oxide, the hydration ratio is as high as 20-25:1, and the content of the obtained ethylene glycol aqueous solution is only 10%. In industry, four-stage distillation is used for dehydration, which consumes a lot of energy.

[0003] Shell once proposed using amine extractants to recover ethylene glycol, such as triethylamine, tripropylamine, N-methylcyclohexylamine, and N,N-dimethylcyclohexylamine. However, our experiments found that the extraction was incomplete and there was also a large amount of water in the extract phase. We also tried other types of extractants but could not find a suitable one. The reason is that ethylene glycol has a high polarity, which makes extraction more difficult.

[0004] Tsinghua University's Liu Dehua mentioned in patent CN1580019A that polyols and aldehydes are reacted with cationic resin to produce cyclic acetals. The boiling point of the selected aldehydes is lower than that of water, so the energy consumption required for aldehyde recovery is low. This process is effective for propylene glycol, but the conversion rate for ethylene glycol is low and there are many by-products. Summary of the Invention

[0005] In view of this, an object of the present invention is to provide a method for concentrating an ethylene glycol aqueous solution to improve the above-mentioned problems.

[0006] The present invention provides a method for concentrating an ethylene glycol aqueous solution, which comprises the following steps:

[0007] S1, modifying the cationic resin with metal ions to obtain a modified cationic resin;

[0008] S2, passing the ethylene glycol aqueous solution and excess butyraldehyde through a packed tower filled with modified cationic resin to react for a period of time; wherein the butyraldehyde serves as both a reactant and an extractant;

[0009] S3, after a period of reaction, the extract is allowed to stand for separation, and a modified cationic resin is used as a catalyst to hydrolyze the extract at a certain temperature, and then butyraldehyde is recovered by distillation to obtain a concentrated ethylene glycol aqueous solution. The metal ions include iron ions, copper ions, and platinum ions.

[0010] Wherein, when the cationic resin is modified with metal ions, the metal loading rate is 1%-20%, preferably 1%-10%.

[0011] The molar ratio of the metal ions of iron ions, copper ions and platinum ions is 1:1:1.

[0012] Wherein, the molar ratio of butyraldehyde to ethylene glycol is 1-6:1, preferably 4-6:1.

[0013] Wherein, in step S2, the reaction temperature is 10°C-90°C, preferably 10°C-40°C.

[0014] Wherein, in step S3, the reaction temperature is 10°C-100°C, preferably 50°C-100°C.

[0015] Among them, also include:

[0016] The raffinate phase is stripped and used as water for hydration of ethylene oxide.

[0017] The implementation of the present invention has at least the following beneficial effects:

[0018] 1. Modification of cationic resin with metal ions can inhibit the occurrence of side reactions in the condensation reaction of ethylene glycol and butyraldehyde. Using platinum metal salts can promote the condensation reaction of ethylene glycol and butyraldehyde and make the reaction more complete. The unmodified resin catalyzes the reaction with 2% byproducts and a conversion rate of 92%.

[0019] 2. This embodiment has the advantages of fast reaction rate, high conversion rate, few side reactions, suitability for continuous production, and the reactant and extractant are the same substance, simple process, low energy consumption, and no wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 The figure is a schematic flow chart of the method for concentrating an ethylene glycol aqueous solution of the present invention. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] See also Figure 1 :

[0024] Example 1

[0025] a) Cationic resin modification: In a 1000 ml three-necked flask, 400 g of D72 cationic resin, 40 ml of 1 mol / L ferric nitrate, 40 ml of 1 mol / L copper nitrate, 40 ml of 1 mol / L platinum chloride, and 40 g of an acrylic adhesive (Satellite Chemical 505) were added and stirred. The mixture was heated to 80° C., reacted for 1 hour, and dried in an oven at 100° C. for 2 hours to obtain D72 modified cationic resin.

[0026] b) Using a peristaltic pump, 450 g of a 10% ethylene glycol aqueous solution and 300 g of 99% butyraldehyde were simultaneously passed through a packed column containing 100 g of the aforementioned D72 modified cationic resin at 25° C. for 0.5 h. The column was allowed to stand for separation, yielding 315 g of an extract with an acetal content of 26.7%, a butyraldehyde content of 69.5%, and a water content of 3.8%. A 435 g raffinate was also obtained with a butyraldehyde content of 6.6% and a water content of 93.4%. The raffinate was distilled to recover 99% butyraldehyde, and the water was used as water for hydration of ethylene oxide.

[0027] c) Acetal hydrolysis: The extract was placed in a distillation apparatus, 20 g of water and 20 g of D72 modified cationic resin were added, and the mixture was stirred at 80° C. for 1 hour at a speed of 400 rpm and distilled at 85° C. A total of 271.2 g of butyraldehyde, 10.9 g of water, and 52.9 g of the bottom liquid were collected. The ethylene glycol content of the bottom liquid was 85.0%, and the water content was 15.0%.

[0028] Example 2

[0029] a) Cationic resin modification: In a 250 ml three-necked flask, 100 g of D72 cationic resin, 10 ml of 1 mol / L ferric nitrate, 10 ml of 1 mol / L copper nitrate, and 10 g of an acrylic adhesive (Satellite Chemical 505) were added and stirred. The mixture was heated to 80°C, reacted for 1 hour, and dried in an oven at 100°C for 2 hours to obtain D72 modified cationic resin.

[0030] b) 450 g of a 10% ethylene glycol aqueous solution and 300 g of 99% butyraldehyde were simultaneously passed through a packed column containing 100 g of the aforementioned D72 modified cationic resin at 25° C. using a peristaltic pump. The flow was completed in 0.5 h and allowed to stand for separation. The resulting extract, 311 g, contained 24.9% acetal, 71.5% butyraldehyde, and 3.6% water. The raffinate, 439 g, contained 6.7% butyraldehyde, 0.8% ethylene glycol, and 92.5% water. The raffinate was distilled to recover 99% butyraldehyde, and the water was used as water for hydration of ethylene oxide.

[0031] c) Acetal hydrolysis: The extract was placed in a distillation apparatus, 20 g of water and 20 g of D72 modified cationic resin were added, and the mixture was stirred at 80° C. for 1 hour at a speed of 400 rpm and distilled at 85° C. A total of 270.6 g of butyraldehyde, 9.5 g of water, and 50.9 g of the bottom liquid were collected. The ethylene glycol content of the bottom liquid was 81.5%, and the water content was 18.5%.

[0032] Example 3:

[0033] a) Cationic resin modification: In a 250 ml three-necked flask, 100 g of D72 cationic resin, 10 ml of 1 mol / L ferric nitrate, 10 ml of 1 mol / L copper nitrate, and 10 g of an acrylic adhesive (Satellite Chemical 505) were added and stirred. The mixture was heated to 80°C, reacted for 1 hour, and dried in an oven at 100°C for 2 hours to obtain D72 modified cationic resin.

[0034] b) 450 g of a 10% ethylene glycol aqueous solution and 300 g of 99% butyraldehyde were simultaneously passed through a packed column containing 100 g of D72 cationic resin at 25° C. using a peristaltic pump. The flow was completed in 0.5 h and allowed to stand for separation. The resulting extract (310 g) contained 24.5% acetal, 71.3% butyraldehyde, 3.7% water, and 0.5% other byproducts. The raffinate (440 g) contained 6.7% butyraldehyde, 0.8% ethylene glycol, and 92.5% water. The raffinate was distilled to recover 99% butyraldehyde, and the water was used as water for hydration of ethylene oxide.

[0035] c) Acetal hydrolysis: The extract was placed in a distillation apparatus, 20 g of water and 20 g of D72 cationic resin were added, and the mixture was stirred at 80° C. for 1 hour at a speed of 400 rpm and distilled at 85° C. A total of 268.1 g of butyraldehyde, 8.5 g of water, and 53.4 g of the bottom liquid were collected. The bottom liquid contained 76.0% ethylene glycol, 2.9% by-products, and 20.1% water.

[0036] Example 4:

[0037] a) Cationic resin modification: In a 250 ml three-necked flask, 100 g of D72 cationic resin, 10 ml of 1 mol / L ferric nitrate, 10 ml of 1 mol / L copper nitrate, 10 ml of 1 mol / L platinum chloride, and 10 g of acrylic adhesive (Satellite Chemical 505) were added and stirred. The mixture was heated to 80°C, reacted for 1 hour, and dried in an oven at 100°C for 2 hours to obtain D72 modified cationic resin.

[0038] b) 450 g of a 10% ethylene glycol aqueous solution and 300 g of 99% butyraldehyde were simultaneously passed through a packed column containing 100 g of the aforementioned D72 modified resin at 25° C. using a peristaltic pump. The flow was completed in 0.5 h and allowed to stand for separation. The extract, 315 g, had an acetal content of 26.7%, a butyraldehyde content of 69.5%, and a water content of 3.8%. The raffinate, 435 g, had a butyraldehyde content of 6.6% and a water content of 93.4%. The raffinate was distilled to recover 99% butyraldehyde, and the water was used as water for hydration of ethylene oxide.

[0039] c) Acetal hydrolysis: The extract was placed in a distillation apparatus, 20 g of water and 20 g of D72 modified cationic resin were added, and the mixture was stirred at 50° C. for 1 hour at a speed of 400 rpm and distilled under reduced pressure at 55° C. A total of 263.2 g of butyraldehyde, 13.2 g of water, and 58.6 g of the bottom liquid were collected. The bottom liquid contained 65.0% ethylene glycol, 22.0% acetal, and 13.0% water.

[0040] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for concentrating an ethylene glycol aqueous solution, characterized in that: The following steps are involved: S1, modifying the cationic resin with metal ions to obtain a modified cationic resin; S2, passing the ethylene glycol aqueous solution and excess butyraldehyde through a packed tower filled with modified cationic resin to react for a period of time; wherein the butyraldehyde serves as both a reactant and an extractant; S3, after a period of reaction, static separation is performed, and the modified cationic resin is used as a catalyst to hydrolyze the extract phase at a certain temperature, and then butyraldehyde is distilled to recover the butyraldehyde to obtain a concentrated ethylene glycol aqueous solution; the metal ions are iron ions, copper ions and platinum ions; when the cationic resin is modified with metal ions, the metal loading rate is 1%-20%; and the metal ion molar ratio of iron ions, copper ions and platinum ions is 1:1:

1.

2. The method according to claim 1, characterized in that The molar ratio of butyraldehyde to ethylene glycol is 1-6:

1.

3. The method according to claim 1, characterized in that In step S2, the reaction temperature is 10°C-90°C.

4. The method according to claim 1, wherein In step S3, the reaction temperature is 10°C-100°C.

5. The method according to claim 1, wherein Also includes: The raffinate phase is stripped and used as water for hydration of ethylene oxide.

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