A method for adsorbing ethylene glycol from an aqueous carbonate solution

Abstract

This invention relates to the fields of petrochemicals and environmental protection, specifically disclosing a method for adsorbing ethylene glycol from carbonate aqueous solutions. By using a specific non-polar macroporous resin as the adsorbent and combining it with appropriate adsorption conditions, the adsorption efficiency of non-polar macroporous resins on ethylene glycol in carbonate aqueous solutions can be improved.

Description

Technical Field

[0001] This invention relates to the fields of petrochemicals and environmental protection, specifically to a method for adsorbing ethylene glycol from an aqueous carbonate solution. Background Technology

[0002] The main technologies related to ethylene oxide / ethylene glycol (EO / EG) include the ethylene process, which uses ethylene and oxygen as raw materials to produce ethylene oxide through oxidation. Ethylene oxide is then converted to ethylene glycol via traditional hydration or catalytic hydrolysis. Currently, the dominant industrial process for ethylene oxide / ethylene glycol worldwide is the direct oxidation of ethylene to ethylene oxide using a silver catalyst, followed by the hydration of ethylene oxide to ethylene glycol. The CO2 removal system is a component of the ethylene oxide / ethylene glycol unit. Its main function is to remove the byproduct CO2 from the EO reaction recirculation gas stream, maintaining a stable concentration of components in the recirculation gas system. Because oxygen is present in the recirculation gas system, CO2 removal requires a hot potassium carbonate solution system. In the circulating gas entering the decarbonization system, the EO content is significantly excessive due to incomplete removal of EO in the preceding EO purification system. The EO content should ideally be controlled at around 5 ppm, but in actual operation, it often far exceeds this level, reaching 50-100 ppm. This results in a large amount of EO being carried into the decarbonization system, reacting with water to form EG (ethylene glycol). Without a proper method to remove EG, it will continuously accumulate in the decarbonization system. Therefore, the concentration of mixed ethylene glycol dissolved in the potassium carbonate decarbonization solution during long-term operation is generally 5-10%, and in some plants, it can even reach as high as 12% of the total decarbonization solution mass. This easily causes foaming and flooding of the solution, affecting the decarbonization efficiency and the safe operation of the equipment. Therefore, there is an urgent need to find an efficient method for removing the glycol. Summary of the Invention

[0003] The purpose of this invention is to overcome the problem of high ethylene glycol content in the carbonate aqueous solution in the decarbonation unit of the existing EOEG device, and to provide a method for adsorbing ethylene glycol from the carbonate aqueous solution, which has a highly efficient alcohol removal effect.

[0004] To achieve the above objectives, the present invention provides a method for adsorbing ethylene glycol from an aqueous carbonate solution, the method comprising: using a non-polar macroporous resin as an adsorbent to adsorb the aqueous carbonate solution;

[0005] The non-polar macroporous resin has a water content of 40-70 wt% and a particle size of 15-50 mesh is not less than 90%.

[0006] The conditions for the adsorption treatment include: pressure of 0.1-5 MPa, temperature of 50-110℃, time of 24-96 h, and liquid hourly space velocity of the carbonate aqueous solution of 0.1-10 h⁻¹.-1 ;

[0007] The ethylene glycol content in the carbonate aqueous solution is 4-15 wt%.

[0008] A second aspect of the present invention provides a decarbonation unit for an EOEG apparatus, which employs the method described in the first aspect of the present invention for adsorbing ethylene glycol from an aqueous carbonate solution.

[0009] The method for adsorbing ethylene glycol from carbonate aqueous solution as described in this invention can improve the adsorption effect of non-polar macroporous resin on ethylene glycol in carbonate aqueous solution by using a specific non-polar macroporous resin as adsorbent and combining it with appropriate adsorption conditions, thereby achieving efficient alcohol removal. Detailed Implementation

[0010] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0011] The present invention provides a method for adsorbing ethylene glycol from an aqueous carbonate solution, the method comprising: using a non-polar macroporous resin as an adsorbent to adsorb the aqueous carbonate solution;

[0012] The non-polar macroporous resin has a water content of 40-70 wt% and a particle size of 15-50 mesh is not less than 90%.

[0013] The conditions for the adsorption treatment include: pressure of 0.1-5 MPa, temperature of 50-110℃, time of 24-96 h, and liquid hourly space velocity of the carbonate aqueous solution of 0.1-10 h⁻¹. -1 ;

[0014] The ethylene glycol content in the carbonate aqueous solution is 4-15 wt%.

[0015] In this invention, the inventors discovered that by using a specific non-polar macroporous resin as an adsorbent and combining it with appropriate adsorption conditions, the alcohol removal efficiency of carbonate solutions with an ethylene glycol content of 4-15 wt% can be improved, especially the alcohol removal efficiency of carbonate solutions with an ethylene glycol content of 6-12 wt%.

[0016] In this invention, preferably, the carbonate aqueous solution is a carbonate aqueous solution obtained from the decarbonation of the tail gas of an ethylene oxidation reactor.

[0017] In this invention, to improve the adsorption effect of the adsorbent, preferably, the non-polar macroporous resin has a water content of 50-60 wt% and a particle size of 15-50 mesh of resin of not less than 95%. More preferably, the non-polar macroporous resin has an average pore radius of 50-400 nm, preferably 70-300 nm, and a specific surface area of ​​800-1000 m². 2 / g, preferably 400-600m 2 / g.

[0018] In this invention, to enhance the synergistic effect of the nonpolar macroporous resin and the carbonate aqueous solution, preferably, the amount of nonpolar macroporous resin used is 20-100 wt%, preferably 30-80 wt%, based on the weight of the carbonate aqueous solution. For example, it can be 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, etc., or any value between these values.

[0019] In this invention, preferably, the adsorption treatment conditions include: a pressure of 0.3-3 MPa, a temperature of 60-100°C, a time of 48-72 h, and a liquid hourly space velocity (LISH) of 0.2-8 h⁻¹ for the carbonate aqueous solution. -1 .

[0020] According to a preferred embodiment, the method for adsorbing ethylene glycol from an aqueous carbonate solution further includes: cleaning the nonpolar macroporous resin with a cleaning agent.

[0021] In this invention, to improve the efficiency of the cleaning process, the cleaning agent is preferably acetone and / or ethanol. More preferably, the cleaning conditions include: a temperature of 15-60°C, preferably 20-50°C, and a time of 15-60 hours, preferably 12-48 hours.

[0022] According to another preferred embodiment, the method for adsorbing ethylene glycol from an aqueous carbonate solution further includes: performing a first desorption treatment on the adsorbed product using a desorption solvent.

[0023] In this invention, preferably, the desorption solvent is selected from acid and / or alkali solutions; the acid is preferably a hydrochloric acid solution; the alkali solution is preferably a sodium hydroxide solution and / or a potassium hydroxide solution. More preferably, the concentration of the acid is 0.05-1 mol / L, preferably 0.1-0.5 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, or any value between these values; the concentration of the alkali is 0.05-3 mol / L, preferably 0.1-1 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, or any value between these values.

[0024] In this invention, to improve the efficiency of the first desorption treatment, preferably, the conditions for the first desorption treatment include: a pressure of 0.3-2.5 MPa, a temperature of 10-80°C, a time of 24-48 h, and a desorbent flow rate of 1-5 BV / h. More preferably, the conditions for the first desorption treatment include: a pressure of 0.5-2 MPa, a temperature of 20-75°C, a time of 24-36 h, and a desorption solvent flow rate of 1-3 BV / h.

[0025] In this invention, to further improve the removal effect of ethylene glycol from carbonate aqueous solution, preferably, the method further includes: using nitrogen gas to perform a second desorption treatment on the product after the desorption treatment.

[0026] In this invention, to improve the efficiency of the second desorption treatment, preferably, the conditions for the second desorption treatment include: pressure of 0.001-0.2 MPa, temperature of 150-300°C, time of 12-36 h, and nitrogen space velocity of 10-400 h⁻¹. -1 More preferably, the conditions for the second desorption treatment include: a pressure of 0.001-0.1 MPa, a temperature of 200-280°C, a time of 12-24 h, and a nitrogen space velocity of 20-300 h⁻¹. -1 .

[0027] In a preferred embodiment of the present invention, the method further includes: performing a third desorption treatment on the product after the desorption treatment using water vapor.

[0028] In this invention, to improve the efficiency of the third desorption treatment, preferably, the conditions for the third desorption treatment include: pressure of 0.1-3 MPa, temperature of 100-300°C, time of 12-48 h, and water vapor space velocity of 100-2000 h⁻¹. -1More preferably, the conditions for the third desorption treatment include: a pressure of 0.1-0.5 MPa, a temperature of 100-150°C, a time of 12-24 h, and a water vapor space velocity of 500-1500 h⁻¹. -1 .

[0029] A second aspect of the present invention provides a decarbonization unit for an EOEG apparatus, wherein the decarbonization unit employs the method for adsorbing ethylene glycol from an aqueous carbonate solution as described in the first aspect of the present invention.

[0030] In this invention, the decarbonization unit of the EOEG unit refers to the decarbonization unit in the ethylene oxide EO / ethylene glycol EG unit, whose function is to remove CO2, a byproduct of the EO reaction, from the circulating gas stream. Generally, the decarbonization unit uses a hot carbonate solution system to remove CO2. However, because EO was not completely removed in the preceding EO purification system, the EO content entering the decarbonization system is significantly excessive and carried into the system, reacting with water to form EG. Without a proper method to remove EG, it will accumulate continuously in the decarbonization system, thus affecting the decarbonization efficiency of the solution and the safe operation of the unit.

[0031] The method for adsorbing ethylene glycol from carbonate aqueous solution as described in this invention enables efficient alcohol removal from carbonate solution in decarbonation unit under specific non-polar macroporous resin and corresponding adsorption conditions, further ensuring the efficiency and stability of decarbonation unit.

[0032] The present invention will be described in detail below through examples. In the following examples, the non-polar macroporous resin was purchased from Ningbo Zhengguang Resin Co., Ltd.

[0033] Example 1

[0034] S1: At 30℃, 1000g of non-polar macroporous resin a1 was cleaned with 1000ml of acetone for 30h; wherein, the non-polar macroporous resin a1 had a water content of 50wt% and a particle size of 15-50 mesh accounted for 98wt%.

[0035] S2: The cleaned nonpolar macroporous resin a1 was mixed with 2000g of carbonate aqueous solution (containing 6wt% ethylene glycol; liquid hourly space velocity was 5h) at 80℃ and 0.5MPa. -1 Adsorption treatment was carried out for 72 hours;

[0036] S3: The product of S2 was mixed with 0.1 mol / L hydrochloric acid solution for the first desorption treatment; the conditions for the first desorption treatment were: pressure of 1 MPa, temperature of 50 °C, time of 24 h, and desorption solvent flow rate of 1 BV / h.

[0037] S4: A second desorption treatment was performed using nitrogen gas mixed with the product from S3; the conditions for the second desorption treatment included: pressure of 0.1 MPa, temperature of 270 °C, time of 12 h, and nitrogen space velocity of 50 h⁻¹. -1 ;

[0038] S5: The third desorption treatment is carried out by mixing water vapor with the product of S4; the conditions for the third desorption treatment are as follows: pressure 0.5 MPa, temperature 150℃, time 12 h, and water vapor space velocity 1500 h⁻¹. -1 .

[0039] Example 2

[0040] S1: At 40℃, 1000g of non-polar macroporous resin a2 was cleaned with 1500ml of acetone for 24h; wherein, the water content of non-polar macroporous resin a2 was 55wt% and the resin with a particle size of 15-50 mesh accounted for 96wt%.

[0041] S2: The cleaned nonpolar macroporous resin a2 was mixed with 1800g of carbonate aqueous solution (containing 8wt% ethylene glycol; liquid hourly space velocity was 4.5h) at 90℃ and 0.8MPa. -1 Adsorption treatment was carried out for 70 hours;

[0042] S3: The product of S2 was mixed with 0.2 mol / L hydrochloric acid solution for the first desorption treatment; the conditions for the first desorption treatment were: pressure of 0.8 MPa, temperature of 60℃, time of 30 h, and desorption solvent flow rate of 1.2 BV / h.

[0043] S4: A second desorption treatment was performed using nitrogen gas mixed with the product from S3; the conditions for the second desorption treatment included: pressure of 0.05 MPa, temperature of 250 °C, time of 15 h, and nitrogen space velocity of 100 h⁻¹. -1 ;

[0044] S5: The third desorption treatment is carried out by mixing water vapor with the product of S4; the conditions for the third desorption treatment are as follows: pressure 0.3 MPa, temperature 130℃, time 15 h, and water vapor space velocity 1800 h⁻¹. -1 .

[0045] Example 3

[0046] The method is similar to that in Example 1, except that in step S2, the carbonate aqueous solution containing 6 wt% ethylene glycol is replaced with the same weight of carbonate aqueous solution containing 4 wt% ethylene glycol.

[0047] Example 4

[0048] The method is similar to that in Example 1, except that in step S2, the carbonate aqueous solution containing 6 wt% ethylene glycol is replaced with the same weight of carbonate aqueous solution containing 15 wt% ethylene glycol.

[0049] Example 5

[0050] The method was similar to that in Example 1, except that step S2 was as follows: the cleaned nonpolar macroporous resin a1 was mixed with 2000g of carbonate aqueous solution (containing 6wt% ethylene glycol; liquid hourly space velocity was 0.1h) at 50°C and 0.1MPa. -1 Adsorption treatment was carried out for 24 hours.

[0051] Example 6

[0052] The method is similar to that in Example 1, except that step S2 is as follows: the cleaned nonpolar macroporous resin is mixed with 2000g of carbonate aqueous solution (containing 6wt% ethylene glycol; liquid hourly space velocity is 10h) at 110℃ and 5MPa. -1 The adsorption process was carried out for 96 hours.

[0053] Example 7

[0054] The method was similar to that in Example 1, except that a non-polar macroporous resin a1 was replaced with a non-polar macroporous resin with a water content of 40 wt% and a particle size of 15-50 mesh of 90 wt%.

[0055] Example 8

[0056] The method was similar to that in Example 1, except that a non-polar macroporous resin a1 was replaced with a non-polar macroporous resin with a water content of 70 wt% and a particle size of 15-50 mesh of 92 wt%.

[0057] Comparative Example 1

[0058] The method was similar to that in Example 1, except that a non-polar macroporous resin a1 was replaced with a non-polar macroporous resin with a water content of 30 wt% and a particle size of 15-50 mesh of 80 wt%.

[0059] Comparative Example 2

[0060] The method is similar to that in Example 1, except that a non-polar macroporous resin a1 is replaced with a non-polar macroporous resin with a water content of 80 wt% and a particle size of 15-50 mesh.

[0061] Comparative Example 3

[0062] The method is similar to that in Example 1, except that in step S2, the carbonate aqueous solution containing 6 wt% ethylene glycol is replaced with the same weight of carbonate aqueous solution containing 20 wt% ethylene glycol.

[0063] Test Example 1

[0064] The ethylene glycol content in the final carbonate aqueous solution of the identification examples and comparative examples is shown in Table 1.

[0065] Test method:

[0066] The content of ethylene glycol in the substrate was determined by HP6890 chromatography combined with internal standard method.

[0067] Table 1

[0068]

[0069] As can be seen from the results in Table 1, Examples 1-8, which use the method of adsorbing ethylene glycol from carbonate aqueous solution according to the present invention, have significantly better effects compared to Comparative Examples 1-3, especially since the ethylene glycol content in the substrates of Examples 1 and 2 is less than 1 wt%.

[0070] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for adsorbing ethylene glycol from an aqueous carbonate solution, characterized in that, The method includes: using a non-polar macroporous resin as an adsorbent to adsorb the carbonate aqueous solution; The non-polar macroporous resin has a water content of 40-70 wt%, and the resin with a particle size of 15-50 mesh is not less than 90 wt%. The conditions of the adsorption treatment include: pressure of 0.1-5 MPa, temperature of 50-110℃, time of 24-96 h, liquid hourly space velocity of the aqueous carbonate solution of 0.1-10 h -1 ; The ethylene glycol content in the carbonate aqueous solution is 4-15 wt%.

2. The method according to claim 1, wherein, The ethylene glycol content in the carbonate aqueous solution is 6-12 wt%. Preferably, the carbonate aqueous solution is a carbonate aqueous solution obtained from the decarbonation of the tail gas of an ethylene oxidation reactor.

3. The method according to claim 1 or 2, wherein, The non-polar macroporous resin has a water content of 50-60 wt% and a particle size of 15-50 mesh of not less than 95 wt%. Preferably, the non-polar macroporous resin has an average pore radius of 50-400 nm, preferably 70-300 nm, a specific surface area of 800-1000 m 2 / g, preferably 400-600 m 2 / g; More preferably, the amount of the nonpolar macroporous resin used is 20-100 wt%, preferably 30-80 wt%, based on the weight of the carbonate aqueous solution.

4. The method according to any one of claims 1-3, wherein, The conditions of the adsorption treatment include: pressure of 0.3-3 MPa, temperature of 60-100℃, time of 48-72 h, liquid hourly space velocity of the aqueous carbonate solution of 0.2-8 h -1 .

5. The method according to any one of claims 1-4, wherein, The method further includes: cleaning the non-polar macroporous resin with a cleaning agent; Preferably, the cleaning agent is acetone and / or ethanol; More preferably, the cleaning conditions include: a temperature of 15-60°C, preferably 20-50°C, and a time of 15-60 hours, preferably 12-48 hours.

6. The method according to any one of claims 1-5, wherein, The method further includes: performing a first desorption treatment on the adsorption-treated product using a desorption solvent; Preferably, the desorption solvent is selected from acid and / or alkaline solutions; the acid is preferably a hydrochloric acid solution; the alkaline solution is preferably a sodium hydroxide solution and / or a potassium hydroxide solution. More preferably, the concentration of the acid solution is 0.05-1 mol / L, preferably 0.1-0.5 mol / L; and the concentration of the alkali solution is 0.05-3 mol / L, preferably 0.1-1 mol / L.

7. The method according to any one of claims 1-6, wherein, The conditions for the first desorption treatment include: pressure of 0.3-2.5 MPa, temperature of 10-80°C, time of 24-48 h, and desorbent flow rate of 1-5 BV / h; Preferably, the conditions for the first desorption treatment include: a pressure of 0.5-2 MPa, a temperature of 20-75°C, a time of 24-36 h, and a desorption solvent flow rate of 1-3 BV / h.

8. The method according to any one of claims 1-7, wherein, The method further includes: performing a second desorption treatment on the product after the desorption treatment using nitrogen gas; Preferably, the conditions for the second desorption treatment include: a pressure of 0.001-0.2 MPa, a temperature of 150-300 °C, a time of 12-36 h, and a nitrogen space velocity of 10-400 h⁻¹. -1 ; More preferably, the conditions for the second desorption treatment include: a pressure of 0.001-0.1 MPa, a temperature of 200-280°C, a time of 12-24 h, and a nitrogen space velocity of 20-300 h⁻¹. -1 .

9. The method according to any one of claims 1-8, wherein, The method further includes: performing a third desorption treatment on the product after the desorption treatment using water vapor; Preferably, the conditions for the third desorption treatment include: a pressure of 0.1-3 MPa, a temperature of 100-300°C, a time of 12-48 h, and a water vapor space velocity of 100-2000 h⁻¹. -1 ; More preferably, the conditions for the third desorption treatment include: a pressure of 0.1-0.5 MPa, a temperature of 100-150°C, a time of 12-24 h, and a water vapor space velocity of 500-1500 h⁻¹. -1 .

10. A decarbonization unit for an EOEG apparatus, characterized in that, The decarbonization unit employs the method for adsorbing ethylene glycol from an aqueous carbonate solution as described in any one of claims 1-9.

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