Degraded sulfolane dechlorination purification treatment method and degraded sulfolane dechlorination purification treatment system

Abstract

The invention relates to the technical field of degraded sulfolane treatment, and discloses a degraded sulfolane dechlorination purification treatment method and a degraded sulfolane dechlorination purification treatment system.The method comprises the steps that the pH of degraded sulfolane is measured; when the pH value of the degraded sulfolane is less than or equal to 7, enabling the degraded sulfolane to sequentially flow through a first resin column and a second resin column; flowing the degraded sulfolane through a second resin column when the pH of the degraded sulfolane is greater than 7; wherein the first resin column is filled with weakly alkaline anion resin, and the second resin column is filled with strongly alkaline anion resin. According to the method, the degraded sulfolane selectively passes through the resin column filled with different anion exchange resins according to the pH value of the degraded sulfolane, the process route is flexible to regulate and control, the operation is simple, the regeneration period of the resin of the resin column can be obviously prolonged, and the wastewater discharge amount of resin regeneration is obviously reduced.

Description

Technical Field

[0001] This invention relates to the field of degraded sulfolane treatment technology, specifically to a method and system for dechlorination and purification of degraded sulfolane. Background Technology

[0002] Sulfolane is one of the ideal solvents for extracting aromatics (benzene, toluene, xylene) from gasoline (reformed gasoline and cracked gasoline, etc.) and is widely used in the petrochemical industry. After a period of operation, the sulfolane solvent deteriorates, causing the solvent in the extraction system to darken in color, the pH value to decrease, severe corrosion of the equipment, and scale buildup that clogs the equipment. This seriously affects the normal operation of the aromatics extraction unit and increases solvent loss.

[0003] Currently, there are many methods for purifying degraded sulfolane through ion exchange resins. Dong Zhi et al., in their "Summary of Industrial Application of Degraded Sulfolane Regeneration Technology" (Refining Technology and Engineering, 2021, 51(8):9-12), used ion exchange to treat degraded sulfolane. A reversible ion exchange transfer reaction occurs at the interface between the solid resin and the solution, removing acidic components and chloride ions from the solvent. This significantly improved the quality of the sulfolane solvent in the aromatic hydrocarbon extraction system, resulting in a significant increase in the pH value of the solvent system and a significant decrease in the chloride content. Li Lin et al., in their "Application of Online Purification Technology for Sulfolane Solvent in Aromatic Hydrocarbon Extraction Units" (China & Foreign Energy, 2022, 27(4):78-82), used a combination of adsorption filtration and ion exchange to remove degraded substances from the sulfolane solvent, thereby regenerating the solvent. The ion exchange utilizes a composite ion exchange resin, which contains both special resin groups for removing acidic degradation products of sulfolane and groups for efficiently removing chloride ions. Acidic substances such as sulfonic acid produced by the degradation of the sulfolane solvent replace the original ions on the resin and are retained by the resin, thereby removing these acidic substances from the sulfolane. CN115672410A describes a regeneration system and method for regenerating sulfolane, in which the regeneration system includes a first resin exchange column and a second resin exchange column arranged in parallel, used to alternately operate to perform ion exchange on the pretreated sulfolane flowing through, regenerating it to obtain regenerated sulfolane.

[0004] Current methods for regenerating degraded sulfolane include passing it sequentially through cation exchange resin columns and anion exchange resin columns in series to improve its properties; however, the slow flow rate of sulfolane through the resin columns limits the throughput per unit time. Another method involves passing degraded sulfolane through parallel anion exchange resin columns, which are used alternately to exchange ions with the pretreated sulfolane flowing through them, regenerating it into regenerated sulfolane. This is achieved by connecting a first resin exchange column and a second resin exchange column in parallel and operating them alternately, using a backwashing unit to backwash the resin exchange column after it becomes saturated and restore it to standby mode. Once the operating resin exchange column becomes saturated, it is switched back to ensure continuous regeneration, but this does not fundamentally extend the regeneration cycle of the exchange resin columns. A third method uses macroporous weak base anion exchange technology alone to regenerate sulfolane, but the deep dechlorination effect is relatively weak. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of short regeneration cycle and insufficient dechlorination effect of the existing ion exchange resin column, and to provide a method and system for dechlorination and purification of degraded sulfolane. This method has the characteristics of high chlorine removal rate and good deep dechlorination effect.

[0006] To achieve the above objectives, the present invention provides a method for dechlorination and purification of degraded sulfolane, the method comprising: measuring the pH of the degraded sulfolane;

[0007] When the pH of the degraded sulfolane is ≤7, the degraded sulfolane is allowed to flow sequentially through the first resin column and the second resin column.

[0008] When the pH of the degraded sulfolane is greater than 7, the degraded sulfolane is allowed to flow through the second resin column;

[0009] The first resin column is filled with a weakly basic anion exchange resin, and the second resin column is filled with a strongly basic anion exchange resin.

[0010] Preferably, the first resin column is regenerated when the chlorine content in the stream exiting the first resin column is higher than 5 mg / L.

[0011] Preferably, the second resin column is regenerated when the chlorine content in the stream exiting the second resin column is higher than 1 mg / L.

[0012] A second aspect of the present invention provides a dechlorination and purification system for degraded sulfolane, the system comprising a degraded sulfolane storage tank and a purification device connected to the degraded sulfolane storage tank via a main feed pipeline.

[0013] The purification device includes a first resin column (1) and a second resin column (2). The first resin column (1) is filled with a weakly basic anion exchange resin, and the second resin column (2) is filled with a strongly basic anion exchange resin. The inlets of the first resin column (1) and the second resin column (2) are each independently connected to the main feed pipeline, and the outlet of the first resin column is connected to the inlet of the second resin column through a pipeline.

[0014] Along the logistics direction, a pH detector (4) and a control valve (3) are sequentially installed on the main feed pipeline. The pH detector (4) is used to measure the pH value of the deteriorated sulfolane from the deteriorated sulfolane storage tank. The control valve (3) is used to control the connection between the main feed pipeline and the feed inlet of the first resin column or the feed inlet of the second resin column.

[0015] Through the above technical solutions, the purification treatment method for degraded sulfolane provided by the present invention selectively passes the degraded sulfolane through a resin column packed with different anion exchange resins according to the pH value of the sulfolane. The process route is flexible and easy to operate. It can make the chloride ion content of the treated sulfolane less than or equal to 1 mg / L, the chloride removal rate ≥90%, and can significantly extend the regeneration cycle of the resin column resin, and significantly reduce the amount of wastewater discharged from resin regeneration. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a degraded sulfolane dechlorination and purification system in some embodiments of the present invention.

[0017] Explanation of reference numerals in the attached figures

[0018] 1. First resin column; 2. Second resin column; 3. Control valve

[0019] 4. pH detector; 5. Deteriorated sulfolane storage tank; 6. Purified sulfolane outlet. Detailed Implementation

[0020] 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.

[0021] The first aspect of the present invention provides a method for dechlorination and purification of degraded sulfolane, the method comprising: measuring the pH of the degraded sulfolane;

[0022] When the pH of the degraded sulfolane is ≤7, the degraded sulfolane is allowed to flow sequentially through the first resin column and the second resin column.

[0023] When the pH of the degraded sulfolane is greater than 7, the degraded sulfolane is allowed to flow through the second resin column;

[0024] The first resin column is filled with a weakly basic anion exchange resin, and the second resin column is filled with a strongly basic anion exchange resin.

[0025] In this invention, degraded sulfolane has the conventional definition in the art, derived from used aromatic hydrocarbon extraction solvents. This invention is applicable to degraded sulfolane of different qualities and compositions, and is capable of removing acidic components and chloride ions from degraded sulfolane. Preferably, the degraded sulfolane has a pH of 2.5-7.5 and a chloride ion content of 5-220 mg / L.

[0026] Existing methods for regenerating degraded sulfolane typically only target the purification and regeneration of degraded sulfolane with a pH below 6. However, they are ineffective at removing trace amounts of chloride ions from degraded sulfolane with a pH above 7, making it difficult to achieve the same level of purification and resulting in poor deep dechlorination.

[0027] The inventors of this invention discovered in their research that by selectively treating degraded sulfolane at different pH values, and selectively passing it through a resin column packed with different anion exchange resins according to the pH value of the degraded sulfolane, the chloride ion content of the treated sulfolane can be less than or equal to 1 mg / L, and the chloride removal rate can be ≥90%. Furthermore, by flexibly adjusting the feed route according to the pH of different degraded sulfolane, the overall operating cycle of the treatment device can be significantly extended, as can the regeneration cycle of the resin column resin, which is beneficial to reducing the wastewater discharge during resin regeneration.

[0028] In this invention, the terms "weakly basic anion exchange resin" and "strongly basic anion exchange resin" have conventional definitions in the art and are distinguished based on the different anion groups they contain. Weakly basic anion exchange resins contain weakly basic groups, such as primary amine groups (also known as primary amino groups) -NH2, secondary amine groups (secondary amino groups) -NHR, or tertiary amine groups (tertiary amino groups) -NR2, which can dissociate into OH groups in water. - It exhibits weak alkalinity. Strongly alkaline anion exchange resins primarily contain stronger reactive groups, such as quaternary ammonium-N... + R3.

[0029] Both the weakly basic anion exchange resin and the strongly basic anion exchange resin can be commercially available products, and the present invention does not have any particular limitations on this.

[0030] According to some preferred embodiments of the present invention, the weakly basic ion exchange resin is selected from at least one of D301, D315, IRA68, and IRA93.

[0031] According to some preferred embodiments of the present invention, the strongly basic anion exchange resin is selected from at least one of D296, D352, IRA900, and IRA401.

[0032] This invention does not impose specific limitations on the conditions under which the degraded sulfolane flows through the resin column; as long as the above-mentioned selective treatment method is met, the purification effect of the degraded sulfolane can be improved. To further improve dechlorination efficiency and extend the regeneration cycle of the resin column, preferably, when the pH of the degraded sulfolane is ≤7, the linear flow rate of the degraded sulfolane is controlled at 0.5-8 m / h, more preferably 0.8-6 m / h.

[0033] When the pH of the degraded sulfolane is ≤7, the degraded sulfolane can flow through the first and second resin columns at any temperature. The contact temperatures of the two resin columns can be the same or different. Preferably, the temperature of the degraded sulfolane flowing through the first resin column is 40-70°C, more preferably 40-60°C. Preferably, the temperature of the degraded sulfolane flowing through the second resin column is 30-60°C, more preferably 30-55°C.

[0034] According to some preferred embodiments of the present invention, when the pH of the degraded sulfolane is >7, the linear flow rate of the degraded sulfolane is controlled to be 0.5-8 m / h, preferably 0.8-6 m / h.

[0035] Preferably, the temperature at which the degraded sulfolane flows through the second resin column is 40-60°C.

[0036] According to some preferred embodiments of the present invention, the volume ratio of the weakly basic anion exchange resin packed in the first resin column to the strongly basic anion exchange resin packed in the second resin column is (1-10):1, for example, it can be a specific volume ratio or any range between 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc. Preferably, the volume ratio of the weakly basic anion exchange resin packed in the first resin column to the strongly basic anion exchange resin packed in the second resin column is (1-5):1.

[0037] According to the present invention, in order to further extend the regeneration cycle of the resin column, preferably, the second resin column is also filled with a weakly basic anion exchange resin. In the above preferred embodiment, the type of weakly basic anion exchange resin in the second resin column can be the same as or different from the type of weakly basic anion exchange resin in the first resin column. The present invention does not particularly limit the filling method of the weakly basic and strongly basic anion exchange resins in the second resin column; they can be mixed or layered, preferably uniformly mixed. The present invention also does not particularly limit the filling density of the anion exchange resins in the two resin columns; conventional filling methods in the art can be used. In the present invention, unless otherwise specified, a loose filling method is used.

[0038] According to some preferred embodiments of the present invention, in the second resin column, the volume ratio of the weakly basic anion exchange resin to the strongly basic anion exchange resin is (0.1-2):1, for example, it can be a specific volume ratio or any range between two such ratios, such as 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, etc. Preferably, in the second resin column, the volume ratio of the weakly basic anion exchange resin to the strongly basic anion exchange resin is (0.1-0.5):1.

[0039] In this invention, when the pH of the degraded sulfolane is greater than 7, the degraded sulfolane only flows through the second resin column. At this time, the first resin column can be regenerated separately without affecting the operation of the second resin column. Thus, by selectively treating degraded sulfolane at different pH values, the continuous purification process is ensured, while avoiding a complete shutdown of the entire unit for regeneration. This improves the unit's operating efficiency and regeneration efficiency, further saving energy and reducing wastewater generation.

[0040] In a further preferred embodiment, the first resin column is regenerated when the pH of the degraded sulfolane is greater than 7 and the chlorine content in the stream exiting the first resin column is greater than 5 mg / L.

[0041] In this invention, the regeneration can be carried out using conventional methods in the art, with the aim of regenerating the weakly basic anion exchange resin in the first resin column.

[0042] According to some preferred embodiments of the present invention, a method for regenerating a first resin column includes: feeding a first regeneration solution into the first resin column and contacting it with a weakly basic anion exchange resin packed in the first resin column.

[0043] According to the present invention, preferably, the linear flow rate of the first regenerated solution fed into the first resin column is 1-10 m / h, more preferably 1-8 m / h.

[0044] Preferably, the temperature at which the first regenerated solution contacts the weakly basic anion exchange resin is 10-30°C, more preferably 20-30°C.

[0045] Preferably, the volume ratio of the first regeneration solution to the volume of the weakly basic anion exchange resin in the first resin column is (5-20):1, more preferably (8-15):1.

[0046] According to some preferred embodiments of the present invention, the regeneration further includes: first feeding an eluent into a first resin column, then washing, and then feeding a regeneration solution into the first resin column. The eluent is used to remove any residual deposited impurities (such as ferric hydroxide) that may remain in the anion exchange resin. Using the above preferred embodiments is beneficial for improving the regeneration effect and extending the service life of the anion exchange resin.

[0047] Preferably, the eluent is an acid solution, preferably an aqueous solution of an inorganic acid, such as an aqueous solution of nitric acid and / or sulfuric acid.

[0048] Preferably, the concentration of the acid solution is 1-5 wt%, more preferably 2-3.5 wt%.

[0049] According to some preferred embodiments of the present invention, the linear flow rate of the eluent fed into the first resin column is 4-16 m / h, preferably 4-14 m / h.

[0050] According to some preferred embodiments of the present invention, the volume ratio of the eluent to the volume of the weakly basic anion exchange resin in the first resin column is (1-20):1, preferably (8-16):1.

[0051] The present invention does not have any particular limitation on the washing method, and water can be used for rinsing.

[0052] According to the present invention, preferably, the second resin column is regenerated when the chlorine content in the stream exiting the second resin column is higher than 1 mg / L. It is understood that regenerating the second resin column requires a complete shutdown. In this case, the decision to regenerate the first resin column can be made based on its actual condition, as described above. That is, when the chlorine content in the stream exiting the first resin column is higher than 5 mg / L, the first resin column is regenerated. If the chlorine content in the stream exiting the second resin column is not higher than 1 mg / L, the device does not need to be shut down. The second resin column can be used to purify the deteriorated sulfolane with pH > 7 until the chlorine content in the stream exiting the second resin column is higher than 1 mg / L, at which point the second resin column is regenerated. By using the two resin columns in conjunction with the above-mentioned preferred regeneration method, the regeneration cycle of the overall device is extended, and the operating efficiency of the device is improved.

[0053] Preferably, the method for regenerating the second resin column includes: feeding a second regeneration solution into the second resin column and contacting it with a strongly basic anion exchange resin and optionally a weakly basic anion exchange resin packed in the second resin column.

[0054] Preferably, the linear flow rate of the second regenerated solution fed into the second resin column is 3-12 m / h, and more preferably 3-10 m / h.

[0055] Preferably, the temperature at which the second regenerated solution contacts the weakly basic anion exchange resin is 10-30°C.

[0056] Preferably, the volume ratio of the second regeneration solution to the volume of the weakly basic anion exchange resin in the second resin column is (10-1):1, more preferably (8-1):1.

[0057] In this invention, the terms "first" and "second" in "first regeneration solution" and "second regeneration solution" are used only to distinguish regeneration solutions from different resin columns and do not indicate the order of operation. This invention allows for a wide range of choices for the first and second regeneration solutions. Preferably, the first and second regeneration solutions are each independently selected from at least one alkaline solution, such as an aqueous solution of sodium hydroxide and / or potassium hydroxide.

[0058] Preferably, the concentration of the first regeneration solution and / or the second regeneration solution is 1-5 wt%, more preferably 2-3.5 wt%.

[0059] According to some particularly preferred embodiments of the present invention, the method for dechlorination and purification of degraded sulfolane includes:

[0060] When the pH of the degraded sulfolane is ≤7, the degraded sulfolane is passed sequentially through the first resin column and the second resin column; when the chlorine content in the stream at the outlet of the first resin column is higher than 5 mg / L, the first resin column is regenerated.

[0061] When the pH of the degraded sulfolane is greater than 7, the degraded sulfolane is passed through the second resin column, and the first resin column is regenerated; when the chlorine content in the stream at the outlet of the second resin column is greater than 1 mg / L, the second resin column is regenerated.

[0062] The first resin column is filled with a weakly basic anion exchange resin, and the second resin column is filled with a strongly basic anion exchange resin and a weakly basic anion exchange resin.

[0063] The volume ratio of the weakly basic anion exchange resin packed in the first resin column, the weakly basic anion exchange resin packed in the second resin column, and the strongly basic anion exchange resin packed in the second resin column is (1-5):(0-0.5):1.

[0064] A second aspect of the present invention provides a degraded sulfolane dechlorination and purification system, such as... Figure 1 As shown, the system includes a deteriorated sulfolane storage tank 5 and a purification treatment device connected to the deteriorated sulfolane storage tank 5 via a main feed pipeline.

[0065] The purification device includes a first resin column 1 and a second resin column 2. The first resin column 1 is filled with a weakly basic anion exchange resin, and the second resin column 2 is filled with a strongly basic anion exchange resin. The inlets of the first resin column 1 and the second resin column 2 are independently connected to the main feed pipeline, and the outlet of the first resin column is connected to the inlet of the second resin column through a pipeline.

[0066] Along the logistics direction, a pH detector 4 and a control valve 3 are sequentially installed on the main feed pipeline. The pH detector 4 is used to measure the pH value of the deteriorated sulfolane from the deteriorated sulfolane storage tank. The control valve 3 is used to control the connection between the main feed pipeline and the feed inlet of the first resin column or the feed inlet of the second resin column.

[0067] Preferably, the second resin column is provided with a purified sulfolane outlet 6, through which purified sulfolane is collected.

[0068] Preferably, the processing system further includes:

[0069] A first regenerator, connected to a first resin column, is used to provide a first regeneration solution to the first resin column to regenerate the first resin column 1; and,

[0070] The second regenerator, connected to the second resin column, is used to provide a second regeneration solution to the second resin column to regenerate the second resin column 2.

[0071] The present invention does not impose any particular limitations on the structure and size of the first resin column and the second resin column, and those skilled in the art can select them according to actual production or experimental needs.

[0072] In this invention, the pH detector can be selected from any online pH meter, as long as it can measure the pH value of the deteriorated sulfolane in the main feed line online.

[0073] The present invention will be described in detail below through embodiments.

[0074] The analytical method for chloride ions was GB / T 40111-2021 Determination of Fluorine, Chlorine and Sulfur Content in Petroleum Products by Combustion Ion Chromatography.

[0075] The resin columns used in the following examples have a diameter of 15 mm and a height of 150 mm.

[0076] Example 1

[0077] The degraded sulfolane dechlorination and purification system used, such as Figure 1 As shown, it includes a deteriorated sulfolane storage tank 5 and a purification treatment device connected to the deteriorated sulfolane storage tank 5 through a main feed pipeline.

[0078] The purification device includes a first resin column 1, a second resin column 2 and a regenerator. The first resin column 1 is filled with a weakly basic anion exchange resin D301, and the second resin column 2 is filled with a mixture of weakly basic anion exchange resin D301 and strongly basic anion exchange resin D296.

[0079] The packing volume ratio of weakly basic anion exchange resin D301 in the first resin column, weakly basic anion exchange resin D301 in the second resin column, and strongly basic anion exchange resin D296 is 1.25:0.25:1.

[0080] The inlets of the first resin column 1 and the second resin column 2 are each independently connected to the main feed pipeline, and the outlet of the first resin column is connected to the inlet of the second resin column through a pipeline; wherein, along the flow direction, a pH detector 4 and a control valve 3 are sequentially installed on the main feed pipeline, and the pH detector 4 is an online pH meter, PHG-21D, from Shanghai Instrument & Electronics Scientific Instruments Co., Ltd.

[0081] The pH of the degraded sulfolane was measured to be 3.5, and the chloride ion content was 160 mg / L. Control valve 3 was adjusted to connect the inlet of the first resin column to the main feed line, allowing the degraded sulfolane to flow sequentially through the first and second resin columns at a linear flow rate of 4 m / h. The temperature of the first resin column was controlled at 45°C, and the temperature of the second resin column at 40°C.

[0082] The purified product was collected from the purified sulfolane outlet 6 of the second resin column, and the chloride ion content was determined to be 0.7 mg / L.

[0083] Example 2

[0084] The degraded sulfolane dechlorination and purification system used, such as Figure 1 As shown, it includes a deteriorated sulfolane storage tank 5 and a purification treatment device connected to the deteriorated sulfolane storage tank 5 through a main feed pipeline.

[0085] The purification device includes a first resin column 1, a second resin column 2 and a regenerator. The first resin column 1 is filled with a weakly basic anion exchange resin D301, and the second resin column 2 is filled with a mixture of weakly basic anion exchange resin D301 and strongly basic anion exchange resin D296.

[0086] The volume ratio of the weakly basic anion exchange resin D301 in the first resin column, the weakly basic anion exchange resin D301 in the second resin column, and the strongly basic anion exchange resin D296 is 1:0.3:0.7.

[0087] The inlets of the first resin column 1 and the second resin column 2 are each independently connected to the main feed pipeline, and the outlet of the first resin column is connected to the inlet of the second resin column through a pipeline; wherein, along the flow direction, a pH detector 4 and a control valve 3 are sequentially installed on the main feed pipeline, and the pH detector 4 is an online pH meter, PHG-21D, from Shanghai Instrument & Electronics Scientific Instruments Co., Ltd.

[0088] The pH of the degraded sulfolane was measured to be 7.5, and the chloride ion content was 32 mg / L. Control valve 3 was adjusted to connect the inlet of the second resin column to the main feed line, allowing the degraded sulfolane to flow through the second resin column at a linear flow rate of 4 m / h. The temperature of the second resin column was controlled at 50℃.

[0089] The purified product was collected from the purified sulfolane outlet 6 of the second resin column, and the chloride ion content was determined to be 0.8 mg / L.

[0090] Example 3

[0091] The method is the same as in Example 1, except that the first resin column 1 is filled with weakly basic anion exchange resin D315, and the second resin column 2 is filled with a mixture of weakly basic anion exchange resin D315 and strongly basic anion exchange resin D352; the volume ratio of the weakly basic anion exchange resin D315 in the first resin column to the strongly basic anion exchange resin D352 in the second resin column is 1:0.4:1.

[0092] The purified product was collected from the purified sulfolane outlet 6 of the second resin column, and the chloride ion content was determined to be 0.9 mg / L.

[0093] Example 4

[0094] The method is the same as in Example 1, except that the first resin column 1 is filled with weakly basic anion exchange resin D301, and the second resin column 2 is filled with strongly basic anion exchange resin D296; the volume ratio of weakly basic anion exchange resin D301 to strongly basic anion exchange resin D296 is 1:1.

[0095] The purified product was collected from the purified sulfolane outlet 6 of the second resin column, and the chloride ion content was determined to be 1 mg / L.

[0096] Example 5

[0097] The method is the same as in Example 1, except that the volume ratio of the weakly basic anion exchange resin D301 in the first resin column, the weakly basic anion exchange resin D301 in the second resin column, and the strongly basic anion exchange resin D296 is 2.5:1.5:1.

[0098] The purified product was collected from the purified sulfolane outlet 6 of the second resin column, and the chloride ion content was determined to be 1 mg / L.

[0099] Example 6

[0100] The method is the same as in Example 1, except that the degraded sulfolane is sequentially flowed through the first and second resin columns at a linear flow rate of 8 m / h. The temperature of the first resin column is controlled at 65°C, and the temperature of the second resin column is controlled at 57°C.

[0101] The purified product was collected from the purified sulfolane outlet 6 of the second resin column, and the chloride ion content was determined to be 1.5 mg / L.

[0102] Comparative Example 1

[0103] The method of Example 3 is different in that the degraded sulfolane dechlorination and purification system used does not contain a second resin column. The degraded sulfolane is passed through only the first resin column, and the treated sulfolane is collected from the outlet of the first resin column. The chloride ion content is measured to be 4.1 mg / L.

[0104] Comparative Example 2

[0105] The method of Example 3 is different except that the control valve 3 is adjusted to connect the inlet of the second resin column to the main feed pipeline, so that the degraded sulfolane flows only through the second resin column.

[0106] The purified product was collected from the purified sulfolane outlet 6 of the second resin column, and the chloride ion content was determined to be 3.9 mg / L.

[0107] Comparative Example 3

[0108] The method is the same as in Example 4, except that the first resin column 1 is filled with a strong basic anion exchange resin D296, and the second resin column 2 is filled with a weak basic anion exchange resin D301.

[0109] The degraded sulfolane was purified according to the method in Example 4. The purified product was collected from the purified sulfolane outlet 6 of the second resin column, and the chloride ion content was measured to be 4 mg / L.

[0110] Example 7 - Continuous Operation Test

[0111] Following the method in Example 1, degraded sulfolane with a pH of 3.5 was first introduced. The inlet of the first resin column was then connected to the main feed pipe via control valve 3, allowing the degraded sulfolane to flow sequentially through the first and second resin columns at a linear flow rate of 4 m / h. Purification continued until the chloride ion content at the outlet of the first resin column exceeded 5 mg / L, with an operating cycle of 15 days.

[0112] Then switch the feed, measure the pH of the degraded sulfolane to be 7.5, adjust control valve 3 to connect the feed inlet of the second resin column to the main feed pipeline, feed the material into the second resin column, and perform continuous purification.

[0113] Simultaneously, the first resin column is regenerated by feeding a 3 wt% H₂SO₄ solution into it at a linear flow rate of 8 m / h and a temperature of 30°C. The volume ratio of the H₂SO₄ solution to the volume of the weakly basic anion exchange resin in the first resin column is 1:1. A 3% NaOH regeneration solution is then fed into the first resin column at a linear flow rate of 6 m / h and a temperature of 30°C. The volume ratio of the NaOH solution to the volume of the weakly basic anion exchange resin in the first resin column is 10:1.

[0114] The process continues until the chloride ion content at the outlet of the second resin column exceeds 1 mg / L. The operating cycle of the second resin column is 25 days. Then, the feed is stopped, the sulfolane material is removed, and the second resin column is regenerated. A 3 wt% NaOH solution is fed into the second resin column at a linear flow rate of 6 m / h and a temperature of 30°C. The volume ratio of the NaOH solution to the volume of the weakly basic anion exchange resin in the second resin column is 5:1. After washing with water, sulfolane regeneration is performed again.

[0115] Example 8

[0116] The method is the same as in Example 7, except that the volume ratio of the weakly basic anion exchange resin D301 to the strongly basic anion exchange resin D296 in the second resin column is 1:0.25.

[0117] Degraded sulfolane with a pH of 3.5 is introduced, and the feed inlet of the first resin column is connected to the main feed pipe through control valve 3. The purification is continued until the chloride ion content at the outlet of the first resin column is greater than 5 mg / L, and the operation cycle is 15 days.

[0118] Then switch the feed, measure the pH of the degraded sulfolane to be 7.5, adjust control valve 3 to connect the feed inlet of the second resin column to the main feed pipeline, feed the second resin column for continuous purification, until the chloride ion content at the outlet of the first resin column is greater than 1 mg / L, and the operating cycle is 6 days.

[0119] Comparative Example 4

[0120] The method is the same as in Example 7, except that the second resin column is filled with the same resin as the first resin column, which is weakly basic anion exchange resin D301.

[0121] Degraded sulfolane with a pH of 3.5 is introduced, and the feed inlet of the first resin column is connected to the main feed pipe through control valve 3. The purification is continued until the chloride ion content at the outlet of the first resin column is greater than 5 mg / L, and the operation cycle is 15 days.

[0122] Then switch the feed, measure the pH of the degraded sulfolane to be 7.5, adjust control valve 3 to connect the feed inlet of the second resin column to the main feed pipeline, feed the second resin column for continuous purification, until the chloride ion content at the outlet of the first resin column is greater than 1 mg / L, and the operation cycle is 2 days.

[0123] The comparison of the above embodiments and comparative examples shows that the purification method for degraded sulfolane provided by the present invention selectively passes it through a resin column packed with different anion exchange resins according to the pH value of the degraded sulfolane. The process route is flexible to control, simple to operate, and has high purification efficiency. The comparison between Example 7 and Comparative Example 4 shows that, compared with the method provided by the present invention, it can significantly extend the overall regeneration cycle of the resin column and significantly reduce the amount of wastewater discharged during resin regeneration.

[0124] 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 dechlorination and purification of degraded sulfolane, characterized in that, The method includes: Determine the pH of degraded sulfolane; When the pH of the degraded sulfolane is ≤7, the degraded sulfolane is allowed to flow sequentially through the first resin column and the second resin column. When the pH of the degraded sulfolane is greater than 7, the degraded sulfolane is allowed to flow through the second resin column; The first resin column is filled with a weakly basic anion exchange resin, and the second resin column is filled with a strongly basic anion exchange resin.

2. The method according to claim 1, wherein, The anionic groups contained in the weakly basic anion exchange resin are selected from at least one of primary amine, secondary amine and tertiary amine groups, preferably at least one of D301, D315, IRA68 and IRA93; Preferably, the anionic group contained in the strongly basic anion exchange resin is a quaternary ammonium group, preferably at least one of D296, D352, IRA900, and IRA401.

3. The method according to claim 1 or 2, wherein, When the pH of the degraded sulfolane is ≤7, the linear flow rate of the degraded sulfolane is controlled to be 0.5-8 m / h, preferably 0.8-6 m / h; Preferably, the temperature at which the degraded sulfolane flows through the first resin column is 40-70°C, and more preferably 40-60°C; Preferably, the temperature at which the degraded sulfolane flows through the second resin column is 30-60°C, and more preferably 30-55°C.

4. The method according to claim 1 or 2, wherein, When the pH of the degraded sulfolane is greater than 7, the linear flow rate of the degraded sulfolane is controlled to be 0.5-8 m / h, preferably 0.8-6 m / h; Preferably, the temperature at which the degraded sulfolane flows through the second resin column is 40-60°C.

5. The method according to any one of claims 1-4, wherein, The volume ratio of the weakly basic anion exchange resin packed in the first resin column to the strongly basic anion exchange resin packed in the second resin column is (1-10):1, preferably (1-5):

1.

6. The method according to any one of claims 1-5, wherein, The second resin column is also filled with a weakly basic anion exchange resin. Preferably, in the second resin column, the volume ratio of weakly basic anion exchange resin to strongly basic anion exchange resin is (0.1-2):1, more preferably (0.1-0.5):

1.

7. The method according to any one of claims 1-6, wherein, When the chlorine content in the stream exiting the first resin column is higher than 5 mg / L, the first resin column is regenerated. Preferably, the method for regenerating the first resin column includes: feeding a first regeneration solution into the first resin column and contacting it with the weakly basic anion exchange resin packed in the first resin column; Preferably, the linear flow rate of the first regenerated solution fed into the first resin column is 1-10 m / h, more preferably 1-8 m / h; Preferably, the temperature at which the first regeneration solution contacts the weakly basic anion exchange resin for regeneration is 10-30°C; Preferably, the volume ratio of the first regeneration solution to the volume of the weakly basic anion exchange resin in the first resin column is (1-20):1, more preferably (8-15):1; Preferably, the regeneration further includes: first feeding the eluent into the first resin column, then washing, and then feeding the regeneration solution into the first resin column; Preferably, the eluent is an acid solution, preferably an aqueous solution of nitric acid and / or sulfuric acid.

8. The method according to any one of claims 1-7, wherein, When the chlorine content in the stream exiting the second resin column is higher than 1 mg / L, the second resin column is regenerated. Preferably, the method for regenerating the second resin column includes: feeding a second regeneration solution into the second resin column and contacting it with a strongly basic anion exchange resin and optionally a weakly basic anion exchange resin packed in the second resin column. Preferably, the linear flow rate of the second regenerated solution fed into the second resin column is 3-12 m / h, more preferably 3-10 m / h; Preferably, the temperature at which the second regenerated solution contacts the weakly basic anion exchange resin is 10-30°C; Preferably, the volume ratio of the second regeneration solution to the volume of the weakly basic anion exchange resin in the second resin column is (10-1):1, more preferably (8-1):

1.

9. The method according to claim 7 or 8, wherein, The first regeneration solution and / or the second regeneration solution are alkaline solutions, preferably aqueous solutions of sodium hydroxide and / or potassium hydroxide; Preferably, the concentrations of the first regeneration solution and the second regeneration solution are each independently selected from 1-5 wt%, more preferably 2-3.5 wt%.

10. A degraded sulfolane dechlorination and purification system, characterized in that, The system includes a deteriorated sulfolane storage tank (5) and a purification treatment device connected to the deteriorated sulfolane storage tank (5) via a main feed pipeline. The purification device includes a first resin column (1) and a second resin column (2). The first resin column (1) is filled with a weakly basic anion exchange resin, and the second resin column (2) is filled with a strongly basic anion exchange resin. The inlets of the first resin column (1) and the second resin column (2) are each independently connected to the main feed pipeline, and the outlet of the first resin column is connected to the inlet of the second resin column through a pipeline. Along the logistics direction, a pH detector (4) and a control valve (3) are sequentially installed on the main feed pipeline. The pH detector (4) is used to measure the pH value of the deteriorated sulfolane from the deteriorated sulfolane storage tank. The control valve (3) is used to control the connection between the main feed pipeline and the feed inlet of the first resin column or the feed inlet of the second resin column. Preferably, the processing system further includes: A first regenerator is used to regenerate the first resin column (1); and, The second regenerator is used to regenerate the second resin column (2).

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