A method for preparing energy-saving ion composite desulfurizer

Abstract

The present application relates to the technical field of composite desulfurizers, and specifically discloses a method for preparing an energy-saving ionic composite desulfurizer. The energy-saving ionic composite desulfurizer is prepared by mixing the following raw materials in parts by mass: 80-85 parts of N-methyldiethanolamine, 5-10 parts of modified defoamer, 5-7 parts of polyethylene glycol dimethyl ether, and 1-3 parts of sodium hexametaphosphate; the modified defoamer is obtained by polymerizing acrylamide monomer, reacting with benzyl protected benzenesulfonic acid, and then undergoing a debenzylation reaction and dissolving in water. The use of the modified defoamer of the present application as an added component of the energy-saving ionic composite desulfurizer can enhance the cycle life of N-methyldiethanolamine, and the obtained energy-saving ionic composite desulfurizer has strong anti-foaming and anti-oxidative degradation properties.

Description

Technical Field

[0001] The present application relates to the technical field of composite desulfurizers, and more specifically, to a method for preparing an energy-saving ionic composite desulfurizer. Background Art

[0002] In the process of natural gas extraction, the raw gas components obtained initially contain some H2S gas. If it is not treated, it will seriously pollute the environment. At the same time, if H2S is accidentally inhaled, it will also cause irreversible damage to the human body. Therefore, when natural gas is extracted, a desulfurization tower needs to be added to adsorb the H2S in the raw gas.

[0003] At present, the most common organic chemical treatment agent used in industry to remove H2S is N-methyldiethanolamine ( ) as the main component of the desulfurizer, which absorbs H2S mainly through the acid-base neutralization reaction between N-methyldiethanolamine and H2S. After the reaction, the gaseous H2S is converted into ionic HS - , dissolves in the desulfurizer solution, thereby achieving the desulfurization effect. The mechanism of action can be expressed by the following reaction equation: HS in ionic state - Dissolved in the desulfurization agent solution, and collected at the bottom of the desulfurization tower along with the desulfurization agent solution. Due to the recyclability and high selectivity of N-methyldiethanolamine to H2S, it has obvious advantages in desulfurization treatment. However, the use of N-methyldiethanolamine also has certain defects.

[0004] On the one hand, N-methyldiethanolamine is prone to foaming during use. This is because as the use time increases, the H2S absorbed by N-methyldiethanolamine continues to accumulate in the desulfurizer solution. - It will corrode the steel desulfurization tower and produce impurities such as FeS that have a foam-stabilizing effect, which will increase the defoaming time of N-methyldiethanolamine foam and cause foam accumulation. In addition, insufficient use of N-methyldiethanolamine will also increase the risk of N-methyldiethanolamine foaming and foaming. On the other hand, N-methyldiethanolamine is also easy to react with a small amount of oxygen mixed in the desulfurizer solution and oxidatively degrade, reducing its use effect. At present, the main method to inhibit the foaming of N-methyldiethanolamine is to add a defoamer to the system and strictly control the introduction of oxygen during the treatment process to avoid problems in the use of N-methyldiethanolamine.

[0005] The Chinese patent application document with publication number CN107569974A discloses a composite desulfurizer and a preparation method thereof. In the patent application document, N-methyldiethanolamine is mixed with a corrosion inhibitor, a defoamer, and a stabilizer, and the reaction activity of the composite desulfurizer is improved by the synergistic effect of each component. The scheme introduces an activator and an organic aluminum compound with a catalytic effect to improve the absorption activity of N-methyldiethanolamine for H2S, thereby reducing the risk of foaming.

[0006] Although the above application document suppresses the foaming of N-methyldiethanolamine by improving the efficiency of N-methyldiethanolamine use, it is still difficult to solve the problem of HS in the treatment liquid. - The problem of foaming of the solution system caused by enrichment, and the problem of self-oxidation and degradation of N-methyldiethanolamine have not been solved. Therefore, there is still a need to find a solution to reduce the foaming of N-methyldiethanolamine and inhibit its self-oxidation and degradation. Summary of the invention

[0007] In order to further reduce the foaming of N-methyldiethanolamine and inhibit its own oxidative degradation, the present application provides a method for preparing an energy-saving ionic composite desulfurizer.

[0008] A method for preparing an energy-saving ionic composite desulfurizer. The energy-saving ionic composite desulfurizer is prepared by mixing the following raw materials in parts by mass: 80-85 parts of N-methyldiethanolamine, 5-10 parts of modified defoamer, 5-7 parts of polyethylene glycol dimethyl ether, and 1-3 parts of sodium hexametaphosphate; the modified defoamer is obtained by polymerizing acrylamide monomer, reacting with benzyl protected benzenesulfonic acid, and then undergoing a debenzylation reaction before being dissolved in water.

[0009] The preparation of the modified defoamer comprises the following steps:

[0010] (S01) Take p-hydroxybenzenesulfonic acid, dissolve it, add potassium carbonate, disperse it, then add benzyl bromide, adjust the temperature and magnetic stirring speed, react, then cool it to room temperature, continue stirring, then use ether to extract, separate the liquid, collect the bottom liquid, and rotary evaporate it at 35-40°C to obtain benzyl protected benzenesulfonic acid;

[0011] (S02) Take acrylamide monomer, add cuprous chloride and azobisisobutylamidine, disperse with water, control the reaction temperature to 45-55°C, react for 15-25 minutes with nitrogen, then cool to room temperature, adjust the pH, add benzyl protected benzenesulfonic acid and catalyst to the system, react at room temperature, then let stand, extract the organic phase with dichloromethane, wash with alcohol after rotary evaporation, and dry to obtain a composite product. The composite product is soluble in water after debenzylation to obtain a modified defoaming agent.

[0012] By adopting the above technical solution, the modified defoamer used can reduce the foaming of N-methyldiethanolamine in the desulfurizer solution and inhibit its oxidative degradation in an oxygen-containing environment. The acrylamide monomer in the modified defoamer is polymerized to form low-polyacrylamide, which can complex with excessive HS - Accumulate FeS and other particles generated by corrosion of the desulfurization tower, and gather these components together to prevent FeS and other particles and other impurities with foam stabilizing effect from mixing into the bubbles formed by the initial foaming of N-methyldiethanolamine, thereby reducing the foam stabilizing effect of the impurity particles. Benzyl protected benzenesulfonic acid grafted with low polyacrylamide exposes highly active phenolic hydroxyl groups after debenzylation reaction, which can act as oxygen-absorbing groups to compete with the ethanol hydroxyl groups in N-methyldiethanolamine for a small amount of oxygen, thereby inhibiting the oxidative degradation of N-methyldiethanolamine.

[0013] Preferably, in the step (S01), the mass ratio of p-hydroxybenzenesulfonic acid to benzyl bromide is 1:(1.38-1.43).

[0014] By adopting the above technical scheme, this process is a substitution reaction of the phenolic hydroxyl group on p-hydroxybenzenesulfonic acid with the benzyl group on benzyl bromide, the hydrogen on the phenolic hydroxyl group is replaced by the benzyl group, forming an ether bond with a more stable chemical structure, thereby protecting the phenolic hydroxyl group. The reaction mass ratio is adjusted to control the molar ratio of benzyl bromide to p-hydroxybenzenesulfonic acid to be between 1.35 and 1.4. The benzyl bromide is slightly excessive in the reaction, so that the phenolic hydroxyl group on the p-hydroxybenzenesulfonic acid is fully protected.

[0015] Preferably, in the step (S01), acetonitrile is used as the dissolving solvent; the temperature is adjusted to 35-37.5°C, and the magnetic stirring speed is 100-150 rpm.

[0016] By adopting the above technical scheme and using acetonitrile as the reaction solvent for benzyl-protected benzenesulfonic acid, the reaction can be promoted, and the temperature and magnetic stirring speed can be adjusted to make the reaction more complete.

[0017] Preferably, in the step (S02), the mass volume ratio of acrylamide monomer, cuprous chloride, azobisisobutylamidine and water is (3.6-4.32) g: (0.2-0.3) g: 0.5 g: (30-35) mL.

[0018] By adopting the above technical solution, this process is a free radical polymerization reaction of acrylamide monomers, and low polyacrylamide is obtained. By adjusting the raw materials and the ratio, the molecular weight of the obtained low polyacrylamide is more uniform.

[0019] Preferably, in the step (S02), the pH is adjusted to 7-7.5.

[0020] Preferably, in the step (S02), the catalyst is prepared by mixing ethanolamine and 4-dimethylaminopyridine in a mass ratio of (5-8): (3-5).

[0021] By adopting the above technical solution, ethanolamine is used as an acid binding agent to promote the forward sulfonamidation reaction and reduce the generation of by-products. 4-dimethylaminopyridine can reduce the energy barrier of the sulfonamidation reaction, so that the sulfonamidation reaction can be carried out under mild conditions. By adjusting the ratio of ethanolamine and 4-dimethylaminopyridine, the catalyst combination obtained has the best effect.

[0022] Preferably, in the step (S02), benzyl protected benzenesulfonic acid is added into the system in an amount of (0.42-0.5) times the mass of the acrylamide monomer.

[0023] By adopting the above technical scheme, the process is a sulfonamidation reaction between the sulfonic acid group on the benzyl-protected benzenesulfonic acid and the amino group on the low polyacrylamide to form sulfonamide, thereby inserting the benzyl-protected benzenesulfonic acid into the low polyacrylamide chain segment. In an alkaline environment, the amino group on the polyacrylamide is fully activated and electrophilically substituted with the sulfonic acid group under the action of the catalyst 4-dimethylaminopyridine to obtain a sulfonamide (-SO2NH-) grafted structure.

[0024] Preferably, in the step (S02), the debenzylation reaction step is as follows: the composite product is mixed with an acid solution, nitrogen is passed through the mixture for reaction, the mixture is then cooled to room temperature, the pH of the solution is adjusted to 7, the organic phase is extracted with ethyl acetate, and the mixture is finally washed with dichloromethane and evaporated to dryness; the acid solution is prepared by mixing hydrochloric acid with a mass fraction of 25%-30%, phosphoric acid solution with a mass fraction of 85%, trifluoroacetic acid, and anhydrous ethanol in a volume ratio of (50-75):(1-2):(5-7):(20-25).

[0025] By adopting the above technical solution, the phenolic hydroxyl group protected in step (S01) can be exposed again, and the prepared acid solution provides a reaction environment for the debenzylation of the composite product, making the debenzylation reaction easier to proceed. During the reaction, the ether bond breaks and the phenolic hydroxyl structure is exposed again. By regulating the debenzylation reaction conditions, the benzyl group can be removed to a greater extent.

[0026] In summary, this application has the following beneficial effects:

[0027] The present application adopts a modified defoamer as an added component of an energy-saving ionic composite desulfurizer, which can improve the anti-foaming and anti-oxidative degradation properties of the energy-saving ionic composite desulfurizer. Low polyacrylamide in the modified defoamer can be used for FeS and other particles and impurity components with a foam-stabilizing effect in the complex treatment liquid, so as to avoid these components being adsorbed on the gas-liquid interface of N-methyldiethanolamine bubbles to increase the liquid film strength, and the problem of continuous foaming of the composite desulfurizer solution. 2. In the present application, it is preferred to use p-hydroxybenzenesulfonic acid and low polyacrylamide for grafting to obtain a modified defoamer. In p-hydroxybenzenesulfonic acid, the phenolic hydroxyl group on the benzene ring has a higher oxidation activity than the ethanolic hydroxyl group on N-methyldiethanolamine, and can preferentially react with a small amount of oxygen mixed in the composite desulfurizer solution, reduce the occurrence of oxidative degradation of N-methyldiethanolamine by reaction with oxygen, and ultimately achieve the effect of extending the service life of N-methyldiethanolamine. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 These are the foaming tendency test results of the energy-saving ionic composite desulfurizers of Examples 1-3 and Comparative Examples 1-2 of the present application.

[0029] Figure 2 These are the test results of the acetic acid content in the deacidified solution after the energy-saving ionic composite desulfurizers of Examples 1-3 and Comparative Examples 1-2 of the present application were circulated. DETAILED DESCRIPTION

[0030] Example 1

[0031] The preparation steps of the energy-saving ionic composite desulfurizer of this embodiment are as follows:

[0032] Take 80g of N-methyldiethanolamine, 5g of modified defoamer, 5g of polyethylene glycol dimethyl ether, and 1g of sodium hexametaphosphate, mix them, and stir for 10min to obtain the product.

[0033] The preparation steps of the modified defoamer in this embodiment are as follows:

[0034] (S01) Take 2.5g of p-hydroxybenzenesulfonic acid and add 20mL of acetonitrile to dissolve, then add 0.2g of potassium carbonate, adjust the magnetic stirring speed to 150rpm, disperse for 5min, then add 3.44g of benzyl bromide, adjust the reaction temperature to 35℃, and the magnetic stirring speed to 100rpm, continue for 5h, and continue stirring at room temperature for 8h. Then add 45mL of ether to the system, stir for 3min, separate the liquid, collect the bottom liquid, and remove the residual ether and acetonitrile by rotary evaporation at 35℃ to obtain benzyl protected benzenesulfonic acid.

[0035] (S02) Take 3.6g of acrylamide monomer, add 0.2g of cuprous chloride, 0.5g of azobisisobutylamidine and 30mL of water, adjust the temperature to 45°C, magnetic stirring speed to 100rpm, react with nitrogen for 15min, then stop heating and cool to room temperature, use a sodium hydroxide solution with a molar concentration of 0.5mol / L to adjust the system pH to 7. Then add 1.8g of benzyl protected benzenesulfonic acid and 0.3g of catalyst, adjust the magnetic stirring speed to 300rpm, react for 1h, and then stand for 2h. Use dichloromethane to extract organic phase A1, remove residual water and dichloromethane in organic phase A1 by rotary evaporation, wash twice with alcohol and dry in an oven at 30°C to obtain a composite product. Then, the composite product was mixed with 45 mL of acid solution, the reaction temperature was adjusted to 40°C, the magnetic stirring speed was 100 rpm, nitrogen was passed through the reaction for 13 hours, and then cooled to room temperature. The pH of the solution was adjusted to 7, and the organic phase B1 was extracted with ethyl acetate. The organic phase B1 was washed twice with dichloromethane, and evaporated in an oven at 30°C. Then, 5 mL of water was added and stirred to dissolve, and the modified defoaming agent was obtained.

[0036] Among them, polyethylene glycol dimethyl ether (purity 99%) was provided by Wuhan Prov Biotechnology Co., Ltd. p-Hydroxybenzenesulfonic acid was provided by Nanjing Datang Chemical Co., Ltd. Acrylamide monomer (model SW925) was provided by Guangzhou Sanwang Chemical Materials Co., Ltd. Azobisisobutylamidine was provided by Shanghai Ruji Biotechnology Development Co., Ltd. The catalyst was prepared by mixing ethanolamine and 4-dimethylaminopyridine in a mass ratio of 5:3. The acid solution was prepared by mixing 25% hydrochloric acid, 85% phosphoric acid solution, trifluoroacetic acid, and anhydrous ethanol in a volume ratio of 50:1:5:20.

[0037] Example 2

[0038] The preparation steps of the energy-saving ionic composite desulfurizer of this embodiment are as follows:

[0039] Take 82g of N-methyldiethanolamine, 8g of modified defoamer, 5g of polyethylene glycol dimethyl ether, and 3g of sodium hexametaphosphate, mix them, and stir for 25min to obtain the product.

[0040] The preparation steps of the modified defoamer in this embodiment are as follows:

[0041] (S01) Take 2.5g of p-hydroxybenzenesulfonic acid and add 20mL of acetonitrile to dissolve, then add 0.3g of potassium carbonate, adjust the magnetic stirring speed to 150rpm, disperse for 5min, then add 3.5g of benzyl bromide, adjust the reaction temperature to 35℃, and the magnetic stirring speed to 150rpm, continue for 6h, and continue stirring at room temperature for 9h. Then add 50mL of ether to the system, stir for 5min, separate the liquid, collect the bottom liquid, and remove the residual ether and acetonitrile by rotary evaporation at 40℃ to obtain benzyl protected benzenesulfonic acid.

[0042] (S02) Take 4g of acrylamide monomer, add 0.25g of cuprous chloride, 0.5g of azobisisobutylamidine and 30mL of water, adjust the temperature to 50°C, magnetic stirring speed to 150rpm, react with nitrogen for 20min, then stop heating and cool to room temperature, use a sodium hydroxide solution with a molar concentration of 0.5mol / L to adjust the system pH to 7. Then add 1.8g of benzyl protected benzenesulfonic acid and 0.3g of catalyst, adjust the magnetic stirring speed to 350rpm, react for 1.5h, and then stand for 3h. Use dichloromethane to extract organic phase A2, remove residual water and dichloromethane in organic phase A2 by rotary evaporation, wash with alcohol 3 times and dry in an oven at 35°C to obtain a composite product. Then, the composite product was mixed with 50 mL of acid solution, the reaction temperature was adjusted to 45 °C, the magnetic stirring speed was 125 rpm, nitrogen was passed through the reaction for 13 h, and then cooled to room temperature. The pH of the solution was adjusted to 7, and the organic phase B2 was extracted with ethyl acetate. The organic phase B2 was washed twice with dichloromethane, and after evaporating in an oven at 30 °C, 5 mL of water was added and stirred to dissolve, and the modified defoaming agent was obtained.

[0043] Among them, polyethylene glycol dimethyl ether (purity 99%) was provided by Wuhan Prov Biotechnology Co., Ltd. p-Hydroxybenzenesulfonic acid was provided by Nanjing Datang Chemical Co., Ltd. Acrylamide monomer (model SW925) was provided by Guangzhou Sanwang Chemical Materials Co., Ltd. Azobisisobutylamidine was provided by Shanghai Ruji Biotechnology Development Co., Ltd. The catalyst was prepared by mixing ethanolamine and 4-dimethylaminopyridine in a mass ratio of 7:4. The acid solution was prepared by mixing 32% hydrochloric acid, 85% phosphoric acid solution, trifluoroacetic acid, and anhydrous ethanol in a volume ratio of 50:1.5:6:25.

[0044] Example 3

[0045] The preparation steps of the energy-saving ionic composite desulfurizer of this embodiment are as follows:

[0046] Take 85 g of N-methyldiethanolamine, 10 g of modified defoamer, 7 g of polyethylene glycol dimethyl ether, and 3 g of sodium hexametaphosphate, mix them, and stir for 30 minutes to obtain the product.

[0047] The preparation steps of the modified defoamer in this embodiment are as follows:

[0048] (S01) Take 2.5g of p-hydroxybenzenesulfonic acid and add 25mL of acetonitrile to dissolve, then add 0.3g of potassium carbonate, adjust the magnetic stirring speed to 175rpm, disperse for 5min, then add 3.57g of benzyl bromide, adjust the reaction temperature to 37.5℃, and the magnetic stirring speed to 150rpm, continue for 6h, and continue stirring at room temperature for 10h. Then add 50mL of ether to the system, stir for 5min, separate the liquid, collect the bottom liquid, and remove the residual ether and acetonitrile by rotary evaporation at 40℃ to obtain benzyl protected benzenesulfonic acid.

[0049] (S02) Take 4.32g of acrylamide monomer, add 0.3g of cuprous chloride, 0.5g of azobisisobutylamidine and 35mL of water, adjust the temperature to 55°C, magnetic stirring speed to 150rpm, react with nitrogen for 25min, then stop heating and cool to room temperature, use a sodium hydroxide solution with a molar concentration of 0.5mol / L to adjust the system pH to 7.5. Then add 1.8g of benzyl protected benzenesulfonic acid and 0.5g of catalyst, adjust the magnetic stirring speed to 350rpm, react for 2h, and then stand for 3h. Use dichloromethane to extract the organic phase A3, rotary evaporation to remove residual water and dichloromethane in the organic phase A3, wash with alcohol 3 times and dry in an oven at 35°C to obtain a composite product. Then, the composite product was mixed with 50 mL of acid solution, the reaction temperature was adjusted to 45°C, the magnetic stirring speed was 150 rpm, nitrogen was passed through the reaction for 15 hours, and then cooled to room temperature. The pH of the solution was adjusted to 7, and the organic phase B3 was extracted with ethyl acetate. The organic phase B3 was washed three times with dichloromethane. After evaporation in an oven at 35°C, 5 mL of water was added and stirred to dissolve, and the modified defoaming agent was obtained.

[0050] Among them, polyethylene glycol dimethyl ether (purity 99%) was provided by Wuhan Prov Biotechnology Co., Ltd. p-Hydroxybenzenesulfonic acid was provided by Nanjing Datang Chemical Co., Ltd. Acrylamide monomer (model SW925) was provided by Guangzhou Sanwang Chemical Materials Co., Ltd. Azobisisobutylamidine was provided by Shanghai Ruji Biotechnology Development Co., Ltd. The catalyst was prepared by mixing ethanolamine and 4-dimethylaminopyridine in a mass ratio of 8:5. The acid solution was prepared by mixing 30% hydrochloric acid, 85% phosphoric acid solution, trifluoroacetic acid, and anhydrous ethanol in a volume ratio of 75:2:7:25.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 2 is that an equal amount of polyaluminum chloride is used instead of acrylamide monomer, which is directly mixed with 2.5 g of p-hydroxybenzenesulfonic acid, and 5 mL of water is added and stirred to dissolve to obtain a modified defoamer; the remaining steps are the same as Example 2.

[0053] Among them, polyaluminium chloride (basicity 45%) is provided by Zhengzhou Yisheng Chemical Co., Ltd.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 2 is that an equal amount of silicone oil is used instead of the modified defoaming agent; the remaining steps are the same as those in Example 2.

[0056] Among them, silicone oil (model: DE-1034) was provided by Hefei Yueguan New Materials Co., Ltd.

[0057] Performance testing

[0058] 1. Foaming tendency test

[0059] Referring to the test methods and standards in the petroleum and natural gas industry standard SY / T6538-2016 "Formulated Selective Desulfurization Solvent", the foaming trend test was conducted on the energy-saving ion composite desulfurizer of Examples 1-3 and Comparative Examples 1-2, and the foaming height and defoaming time of each solution were recorded. The test results are as follows: Figure 1 shown.

[0060] 2. Desulfurization performance test

[0061] Referring to the test method and standard in the petroleum and natural gas industry standard SY / T6538-2016 "Formulated Selective Desulfurization Solvent", the energy-saving ion composite desulfurizers of Examples 1-3 and Comparative Examples 1-2 were diluted with water to prepare a desulfurizer solution with a mass fraction of 40%, and then the desulfurizer solution was added to a liquid storage tank, which can be introduced into a desulfurization tower through a pipeline. During the test, the raw natural gas was introduced from the bottom of the desulfurization tower, and the desulfurizer solution was introduced from the top of the desulfurization tower, and the purified gas obtained was separated and measured from the top of the desulfurization tower.

[0062] Table 1 Desulfurization test conditions of energy-saving ion composite desulfurizer in Example 1-3 and Comparative Example 1-2

[0063]

[0064] Table 2 H2S content in purified gas after treatment with energy-saving ion composite desulfurizer of Example 1-3 and Comparative Example 1-2

[0065]

[0066] 3. Oxidative degradation test

[0067] N-methyldiethanolamine undergoes self-oxidation during use, and the reaction in which the oxidation degradation product is acetic acid can be expressed as: By monitoring the acetic acid content in the circulating post-treatment liquid, the degree of oxidative degradation of N-methyldiethanolamine can be determined.

[0068] According to the desulfurization test conditions in Table 1, the energy-saving ionic composite desulfurizers of Examples 1-3 and Comparative Examples 1-2 were respectively formulated into desulfurizer solutions with a mass fraction of 40% for testing to obtain desulfurization treatment liquids. After each group of desulfurization treatment liquids was subjected to pressure reduction flash evaporation, heat exchange, and stripping steps to remove the adsorbed acidic H2S gas, a deacidified liquid was obtained, and the desulfurization liquid was recycled and added to the desulfurization tower for adsorbing H2S gas. Five cycles were carried out under the test conditions, and 50 mL of the initial desulfurizer solution of each group was taken as a standard, and compared with the same amount of the deacidified liquid of each group after the first, third, and fifth cycles by mass spectrometry analysis, and the content of acetic acid in the oxidative degradation products of each group after the cycle was calculated. The test results are as follows: Figure 2 shown.

[0069] Analyze Examples 1-3 and Comparative Examples 1-2 and combine Figure 1 It can be seen from Tables 1-2 that the foaming height and defoaming time of the energy-saving ionic composite desulfurizer prepared by Example 2 are at the lowest level in all test groups, indicating that the composite desulfurizer obtained by the scheme of Example 2 has the strongest anti-foaming performance, and Examples 1-3 also show high absorption of H2S. After polyaluminum chloride is used instead of low polyacrylamide in Comparative Example 1, the foaming height of the solution increases significantly, and the foaming degree is higher than that of the silicone oil used in Comparative Example 2. This may be because in Comparative Example 1, polyaluminum chloride is peptized in the composite desulfurizer solution to obtain Al(OH) 2+ These polymers react with HS in solution - The reaction produces substances that promote foam stabilization, resulting in a significant increase in foam height and defoaming time.

[0070] Analyze Examples 1-3 and Comparative Examples 1-2 and combine Figure 2 It can be seen that as the number of cycles increases, the acetic acid content in the deacidification solution gradually increases, indicating that the oxidative degradation of N-methyldiethanolamine gradually accelerates. From the perspective of oxidative degradation trend, the oxidative degradation of the embodiment scheme is relatively stable, indicating that the energy-saving ionic composite desulfurizers of Examples 1-3 have good anti-oxidative degradation performance. Among the 5 schemes, the oxidative degradation of the comparative example 2 scheme is the most obvious, which may be because the comparative example 2 uses silicone oil instead of the modified defoamer, and the oxidative activity of the silicone hydroxyl group on the silicone oil in the desulfurizer solution treatment environment is weaker than that of the ethanol hydroxyl group on N-methyldiethanolamine, and the small amount of oxygen mixed in the desulfurizer solution directly reacts with N-methyldiethanolamine, resulting in the greatest degree of oxidative degradation in the comparative example 2.

[0071] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing an energy-saving ionic composite desulfurizer, characterized in that: The energy-saving ionic composite desulfurizer is prepared by mixing the following raw materials in parts by mass: 80-85 parts of N-methyldiethanolamine, 5-10 parts of modified defoamer, 5-7 parts of polyethylene glycol dimethyl ether, and 1-3 parts of sodium hexametaphosphate; the modified defoamer is obtained by polymerizing acrylamide monomer, reacting with benzyl protected benzenesulfonic acid, and then undergoing a debenzylation reaction before being dissolved in water; The benzyl protected benzenesulfonic acid is prepared by the following steps: (S01) taking p-hydroxybenzenesulfonic acid, dissolving it, adding potassium carbonate, dispersing it, then adding benzyl bromide, adjusting the temperature and magnetic stirring speed, reacting, then cooling to room temperature, continuing to stir, then using ether to extract, separating the liquids, collecting the bottom liquid, and rotary evaporating at 35-40°C to obtain benzyl protected benzenesulfonic acid.

2. The method for preparing an energy-saving ionic composite desulfurizing agent according to claim 1, characterized in that: The preparation of the modified defoamer comprises the following steps: (S02) Take acrylamide monomer, add cuprous chloride and azobisisobutylamidine, disperse with water, control the reaction temperature to 45-55°C, react for 15-25 minutes with nitrogen, then cool to room temperature, adjust the pH, add benzyl protected benzenesulfonic acid and catalyst to the system, react at room temperature, then let stand, extract the organic phase with dichloromethane, wash with alcohol after rotary evaporation, and dry to obtain a composite product. The composite product is soluble in water after debenzylation to obtain a modified defoaming agent.

3. The method for preparing an energy-saving ionic composite desulfurizing agent according to claim 2, characterized in that: In the step (S01), the mass ratio of p-hydroxybenzenesulfonic acid to benzyl bromide is 1:(1.38-1.43).

4. The method for preparing an energy-saving ionic composite desulfurizing agent according to claim 2, characterized in that: In the step (S01), the temperature is adjusted to 35-37.5°C and the magnetic stirring speed is 100-150 rpm.

5. The method for preparing an energy-saving ionic composite desulfurizing agent according to claim 2, characterized in that: In the step (S02), the mass volume ratio of acrylamide monomer, cuprous chloride, azobisisobutylamidine, and water is (3.6-4.32) g: (0.2-0.3) g: 0.5 g: (30-35) mL.

6. The method for preparing an energy-saving ionic composite desulfurizing agent according to claim 2, characterized in that: In the step (S02), the catalyst is prepared by mixing ethanolamine and 4-dimethylaminopyridine in a mass ratio of (5-8): (3-5).

7. The method for preparing an energy-saving ionic composite desulfurizing agent according to claim 2, characterized in that: In the step (S02), benzyl protected benzenesulfonic acid is added into the system in an amount of (0.42-0.5) times the mass of the acrylamide monomer.

8. The method for preparing an energy-saving ionic composite desulfurizing agent according to claim 2, characterized in that: In the step (S02), the debenzylation reaction step is as follows: the composite product is mixed with an acid solution, nitrogen is passed through for reaction, then cooled to room temperature, the pH of the solution is adjusted to 7, the organic phase is extracted with ethyl acetate, and finally washed with dichloromethane and evaporated to dryness.

9. The method for preparing an energy-saving ionic composite desulfurizing agent according to claim 8, characterized in that: The acid solution is prepared by mixing hydrochloric acid with a mass fraction of 25%-30%, phosphoric acid solution with a mass fraction of 85%, trifluoroacetic acid, and anhydrous ethanol in a volume ratio of (50-75): (1-2): (5-7): (20-25).

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