A nonionic surfactant removing agent, its preparation method and application

Abstract

The application discloses a non-ionic surfactant removing agent and a preparation method and application thereof. The removing agent is a porous polymer microsphere loaded with boric acid in a pore channel, and is obtained by suspension copolymerization of an acrylate monomer, an aliphatic diene crosslinking agent and a porogen in water, and then soaked in a boric acid solution to load boric acid. The removing agent has high selectivity to non-ionic surfactants and sulfolane, and can realize removal of non-ionic surfactants in a desulfurization solution containing sulfolane. Specifically, the active component boric acid in the pore channel of the porous polymer microsphere can be complexed with the entering non-ionic surfactants, and cannot be complexed with sulfolane, so that selective adsorption of the two is realized, deep removal of the non-ionic surfactants in the sulfolane is realized, the loss rate of the sulfolane is low, and meanwhile, new impurities are not introduced after removal of the non-ionic surfactants in the sulfolane.

Description

Technical Field

[0001] This invention relates to the field of functional polymer materials, specifically to a nonionic surfactant remover, its preparation method, and its application. Background Technology

[0002] Many raw natural gas samples extracted from underground reservoirs contain impurities such as H2S and organic sulfur, and cannot be used directly. They must undergo desulfurization and purification to become usable commercial natural gas. Commercial natural gas has regulations specifying the sulfur content, with the current requirement for total sulfur being ≤20 mg / m³. 3 .

[0003] Organic sulfur removal technology must be used to control the organic sulfur content in the product natural gas to a very low level to achieve a total sulfur content of ≤20 mg / m³. 3 The requirements of the indicators are met. Therefore, the demand for organic sulfur removal technology and organic sulfur removal solutions in the natural gas purification field is rapidly increasing.

[0004] Sulfolane is an excellent solvent for organic sulfur compounds, exhibiting a high removal rate. It is considered the preferred solvent for removing organic sulfur compounds from natural gas. The number of purification plants using sulfolane and sulfolane-based physicochemical desulfurization solutions is rapidly increasing.

[0005] Desulfurization solutions are easily contaminated and deteriorated by residues from upstream mining operations during natural gas purification. Foaming due to contamination of the desulfurization solution is the most common and widespread problem in natural gas purification production, and a major factor restricting stable and increased production. Therefore, amine reactivation technology, which can remove foaming contaminants from desulfurization solutions and restore their performance, is a key technology for ensuring stable production in natural gas purification plants. However, existing amine reactivation technologies, when used with sulfolane and sulfolane-based physicochemical desulfurization solutions, cannot effectively separate the foaming agents. The resulting foaming of the desulfurization solution leads to substandard natural gas quality, unstable operation of the natural gas purification unit, and even production stoppages, seriously affecting normal production. Therefore, the need for foaming agent removal technology from sulfolane is extremely urgent in the natural gas purification field.

[0006] Various surfactants in the residues of natural gas extraction operations are the cause of foaming in desulfurization solutions. For example, nonionic surfactants are present in foam draining, demulsifying, corrosion inhibitors, drilling agents, and oil displacement agents. To solve the problem of foaming in desulfurization solutions, these surfactants must be removed.

[0007] Anionic and cationic surfactants can ionize in aqueous solutions, and their ionization properties differ significantly from those of sulfolane. Furthermore, the interaction between anionic / cationic surfactant molecules and sulfolane molecules weakens upon the addition of water. Therefore, the development of removal agents for anionic / cationic surfactants from sulfolane can find a technological breakthrough by addressing these differences in properties. However, nonionic surfactants possess adsorption characteristics extremely similar to sulfolane molecules, including polarity, magnetism, ionization, and organic / inorganic properties, exhibiting very strong affinity for sulfolane. Sulfolane is a suitable choice for extracting nonionic surfactants, but conversely, separating nonionic surfactants from sulfolane is extremely difficult. Existing adsorption materials lack selectivity for both sulfolane and nonionic surfactants. In the presence of high concentrations of sulfolane (50 times or more the concentration of nonionic surfactants in physicochemical desulfurization solutions), the removal rate of nonionic surfactants is extremely low (<10%), and even distillation methods yield only a low removal rate (<30%). Furthermore, because surfactants at concentrations of a few hundred ppm can cause severe foaming in desulfurization solutions, the required depth of surfactant removal from the desulfurization solution is very high. Separating sulfolane from surfactants is already difficult, and achieving deep removal is even more challenging. Therefore, despite its long-standing use in natural gas purification, the problem of how to revive sulfolane after it becomes contaminated and foams has remained unresolved. The only solution to restore production is replacement with a new solvent. The contaminated solution removed from the unit is treated as waste. A single desulfurization unit typically generates over 400 tons of waste due to contamination. Since sulfolane-based desulfurization solutions contain organic matter at a rate of 70% or higher, and also contain toxic components such as hydrogen sulfide, their disposal as hazardous waste is extremely difficult and costly, placing a significant economic burden and environmental pressure on purification plants.

[0008] Existing purification technologies for modified sulfolane include ion exchange separation, precipitation separation, activated carbon adsorption, and decomposition. 1) Ion exchange separation uses anion exchange resins to purify modified sulfolane, as illustrated in patents US5053137, CN1230545A, CN1644581A, CN1076726C, CN1125063C, CN111111306A, and CN1861594A. The anion exchange resins used are styrene-divinylbenzene polymers containing primary, secondary, or quaternary ammonium groups. Anion exchange resins can only remove ionic substances from the solution. Nonionic surfactants do not ionize in water or sulfolane and therefore cannot be removed by ion exchange resins. 2) Precipitation separation method, such as patent US4820849, involves adding polybasic acids or polybasic anhydrides to sulfolane solvent to form solid precipitates with acidic impurities; alkali adsorption separation method, such as Japanese patents JP7-278316, CN1634917A, and CN106957297A, uses oxides, hydroxides, and carbonates of alkali metals or alkaline earth metals to adsorb acidic impurities in sulfolane. Both of these methods can only remove acidic impurities from sulfolane. Nonionic surfactants are not acidic substances, so neither of these methods can remove nonionic surfactants. 3) Activated carbon adsorption method, as described in Japanese patent JP7-101953, uses activated carbon and microfibrous natural cellulose to remove suspended microparticles and dissolve ionic impurities. Activated carbon exhibits no selectivity for the adsorption of sulfolane and nonionic surfactants, with a selectivity ratio <2. In sulfolane desulfurization solutions, the concentration of sulfolane is much higher than that of nonionic surfactants. Due to this concentration advantage, sulfolane occupies the activated carbon adsorption surface before nonionic surfactants, causing it to quickly become saturated. This results in a nonionic surfactant removal rate of less than 10%. 4) Decomposition method: CN213885678U decomposes some of the acidic substances in sulfolane by adding monoethanolamine. Nonionic surfactants cannot be decomposed by monoethanolamine, so this method is also not applicable.

[0009] Existing purification technologies for desulfurization solutions include: ion exchange, electrodialysis, vacuum distillation, activated carbon adsorption separation, and foaming impurity removal technology. Among these technologies, ion exchange and electrodialysis can only remove salt impurities from the desulfurization solution, such as those listed in US6517700, US5162084, US5788864, CN1733355A, CN1230545A, and CN102189008A. Vacuum distillation suffers from high sulfolane loss and low removal rate of nonionic surfactants. Activated carbon adsorption separation and the foaming impurity removal technology independently developed by the Southwest Oil & Gas Field Company have a non-selective adsorption rate for sulfolane and nonionic surfactants, resulting in a nonionic surfactant removal rate of less than 10%.

[0010] Currently, the main methods for treating nonionic surfactant wastewater include foam separation, adsorption, biological methods, micro-electrolysis, and Fenton oxidation. Foam separation is a commonly used physical method that removes nonionic surfactants from foam by bubbling. This method is simple to operate and effectively separates nonionic surfactants. However, for heavily foamed sulfolane desulfurization solutions, the entire solution foams after bubbling, and even after foam separation, 80-90% of the sulfolane is lost. For example, patent CN107935236A uses adsorbent material particles to adsorb surfactants in wastewater, and then bubbling allows the adsorbent material particles to accumulate on the wastewater surface before removal. The adsorbent particles include silica, calcium carbonate, calcium sulfate, activated carbon particles, magnetite powder, hematite powder, titanium dioxide, clay minerals, fly ash or phosphate rock tailings powder, as well as nanoparticles of iron tetroxide, silica, titanium dioxide, and zinc oxide metal oxides synthesized through wet chemical processes; silica and titanium dioxide with amino or carboxyl groups modified on their surfaces; and polystyrene resin particles, phenolic resin particles, or melamine resin particles, including unmodified polystyrene resin particles, unmodified phenolic resin particles, or unmodified melamine resin particles. These adsorbents lack selectivity for sulfolane and nonionic surfactants, exhibiting not only low removal rates of nonionic surfactants from sulfolane but also significant sulfolane loss. The adsorption method, as described in the literature "Research on the Treatment of Nonionic Surfactant Wastewater with Modified Fly Ash," involves modifying fly ash with reagents such as hydrochloric acid and sulfuric acid to prepare a fly ash adsorbent coagulant. This modified fly ash adsorbent coagulant is then used to treat wastewater containing nonionic surfactants such as alkylphenol polyoxyethylene ether. The results show that the modified fly ash exhibits good adsorption performance for wastewater containing alkylphenol polyoxyethylene ether at concentrations of 300–1800 mg / L. However, the modification process requires the addition of hydrochloric acid and sulfuric acid, which can cause secondary pollution by flowing into the wastewater and increasing the difficulty of subsequent wastewater treatment. This method, which causes secondary pollution, is even less suitable for sulfolane. The introduction of hydrochloric acid and sulfuric acid into sulfolane not only causes corrosion but also leads to a decrease in its desulfurization performance or even complete failure, making it unsuitable. The biological method utilizes microorganisms to use nonionic surfactants as a carbon source to degrade them in wastewater. Sulfolane and similar substances are also organic matter and will be degraded simultaneously, making this method unsuitable. Micro-electrolysis is based on electrochemical principles. It involves forming electrode reactions in wastewater to cause nonionic surfactants to undergo catalytic oxidation, coagulation, adsorption, complexation, and displacement reactions, thereby rapidly removing pollutants. Fenton oxidation utilizes ferrous ions in Fenton's reagent as a catalytic initiator. Under its action, H2O2 generates a large number of free radicals, which further accelerates the initiation of free radical chains, thus enabling the rapid degradation and removal of nonionic surfactants in wastewater.These two methods are often used in combination, as described in patents CN110357357A, CN1508077A, CN104310665, and CN109626675A. These methods require first adding acid to adjust the pH to 0.5–5, then introducing ferric and ferrous ions. These methods are unsuitable for sulfolane because adding acid reduces its desulfurization performance or even causes complete failure, increases its corrosiveness, and the precipitation formed when ferric and ferrous ions come into contact with hydrogen sulfide can lead to blockage of the desulfurization equipment.

[0011] In summary, existing technologies have very low removal rates of nonionic surfactants from sulfolane (<30%), lack selectivity in the removal of sulfolane and nonionic surfactants (selectivity ratio <2), have high sulfolane loss rates, and some technologies may introduce new impurities into the solution, leading to poorer desulfurization performance and increased corrosivity. Summary of the Invention

[0012] One object of the present invention is to provide a nonionic surfactant remover and a method for preparing the same.

[0013] Another object of the present invention is to provide an application of the aforementioned nonionic surfactant remover, particularly in the deep removal of nonionic surfactants from sulfolane, to solve the problems of poor selectivity and low removal rate of nonionic surfactants from sulfolane in the prior art.

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] This invention provides a method for preparing a nonionic surfactant remover, wherein the preparation method includes the following steps:

[0016] Porous polymer microspheres were obtained by suspending and copolymerizing acrylate monomers, aliphatic diene crosslinking agents and pore-forming agents in water.

[0017] The porous polymer microspheres were soaked in a boric acid solution, then filtered out and dried to obtain the removal agent.

[0018] The removal agent prepared in this invention exhibits high selectivity for nonionic surfactants and sulfolane, enabling the removal of nonionic surfactants from desulfurization solutions containing sulfolane. Specifically, the active component boric acid within the porous polymer microspheres can complex with the introduced nonionic surfactants without complexing with sulfolane, thereby achieving selective adsorption of both and achieving deep removal of nonionic surfactants from sulfolane with a low sulfolane loss rate; simultaneously, it ensures that no new impurities are introduced after the removal of nonionic surfactants from sulfolane.

[0019] In some embodiments of the present invention, the structural formula of the acrylate monomer is as follows: Wherein R is a C1 to C5 alkyl group, and preferably, the acrylate monomer is methyl acrylate or hexyl acrylate, more preferably hexyl acrylate.

[0020] Sulfolane has a weak affinity for alkanes but a strong affinity for aromatics. Therefore, this invention does not choose styrene, a commonly used monomer, but instead uses acrylate. While the ester groups in acrylate have some adsorption capacity for sulfolane, the alkyl groups exhibit a shielding effect on the adsorption of sulfolane by the ester groups. The more carbon atoms in the alkyl group, the greater the shielding effect. However, an excessively large number of alkyl groups may generate long polyacrylate segments and linear acrylate homopolymers during polymerization, causing the prepared remover to clump together during use. The number of alkyl groups in hexyl acrylate best balances these two issues, satisfying both a sufficiently strong shielding effect for extremely weak sulfolane adsorption and preventing clumping of the remover during use. Therefore, hexyl acrylate is the preferred acrylate monomer in this invention.

[0021] In some embodiments of the present invention, preferably, the aliphatic diene crosslinking agent is ethylene glycol dimethacrylate.

[0022] The polymer stripper of this invention selects an aliphatic diene as the crosslinking agent, rather than the conventional phenyl-containing divinylbenzene, because phenyl groups adsorb sulfolane. Preferred dimethacrylate (ethylene glycol dimethacrylate) increases the swelling degree of the copolymer, resulting in a higher interchain distance in the final polymer, which facilitates the penetration of larger molecular weight nonionic surfactants.

[0023] In some embodiments of the present invention, preferably, the pore-forming agent is selected from at least one of isooctyl alcohol, n-decane, decanol, and 2-ethyl-1-hexanoic acid.

[0024] The micropores prepared using isooctyl alcohol, n-decane, decanol, and 2-ethyl-1-hexanoic acid have a pore size that is suitable for the subsequent introduction of the active component boric acid, without being too large to weaken the potential energy superposition effect of each plane. Other porogens either result in a lower loading of the active component boric acid or weaker adsorption of nonionic surfactants, which may lead to the problem of a small amount of adsorbed nonionic surfactants being desorbed.

[0025] In some embodiments of the present invention, preferably, the porogen is selected from at least one of n-decane, decanol, and 2-ethyl-1-hexanoic acid.

[0026] In some embodiments of the present invention, preferably, the molar ratio of the acrylate monomer, the aliphatic diene crosslinking agent, and the porogen is 1:(0.07-0.3):(0.1-0.8).

[0027] When the crosslinking agent dosage is higher than 0.3%, the internal structure of the resulting porous polymer microspheres will be too dense, increasing the shuttle resistance of nonionic surfactant molecules within the microspheres. This is detrimental to both adsorption and desorption during regeneration, resulting in a low removal rate. When the crosslinking agent dosage is lower than 0.07%, the resulting porous polymer microspheres will aggregate in sulfolane desulfurization solution. When the porogen dosage is lower than 0.1%, the pore capacity and specific surface area of ​​the resulting porous polymer microspheres are too low, with an adsorption capacity <10 mg / g, which does not meet the usage requirements. When the porogen dosage is higher than 0.8%, the porous polymer microspheres will exhibit poor strength and internal pore structure collapse.

[0028] In some embodiments of the present invention, more preferably, the molar ratio of the acrylate monomer, the aliphatic diene crosslinking agent, and the porogen is 1:(0.1-0.2):(0.5-0.6).

[0029] In some embodiments of the present invention, preferably, the boric acid solution is a saturated boric acid solution at 80-90°C.

[0030] High-concentration boric acid solutions are beneficial for boric acid loading, but boric acid has very low solubility in cold water. Increasing the temperature can increase its solubility; however, the solution tends to boil above 90°C, which is not conducive to the deposition of boric acid on microspheres. Therefore, the present invention preferably uses a saturated boric acid solution at 80–90°C.

[0031] In some embodiments of the present invention, preferably, the mass ratio of boric acid to porous polymer microspheres is >0.1. Too little boric acid will result in the adsorption capacity of the resulting remover for nonionic surfactants being <10 mg / g, which does not meet the usage requirements.

[0032] In some embodiments of the present invention, more preferably, the mass ratio of boric acid to porous polymer microspheres is 0.7:1.

[0033] In some embodiments of the present invention, preferably, the soaking time is >0.5h.

[0034] In some embodiments of the present invention, more preferably, the soaking time is 5h to 6h.

[0035] When the soaking time is less than 0.5 h, the adsorption capacity of the resulting remover for nonionic surfactants is <10 mg / g, which does not meet the usage requirements. After the soaking time exceeds 6 h, the adsorption capacity of the remover no longer increases.

[0036] In some embodiments of the present invention, preferably, the soaking temperature is 50-90°C. At this temperature, the solubility of boric acid is high. Above 90°C, the solution tends to boil, which is not conducive to the deposition of boric acid on the microspheres.

[0037] In some embodiments of the present invention, preferably, the drying temperature is 100–165°C.

[0038] In some embodiments of the present invention, more preferably, the drying temperature is 120–140°C.

[0039] When the drying temperature is above 165℃, boric acid tends to decompose into metaboric acid. A temperature of 120-140℃ can ensure drying without decomposing boric acid, and the drying time is short.

[0040] In another aspect, the present invention provides a nonionic surfactant remover, which is obtained by any of the above preparation methods.

[0041] The remover is a porous polymer microsphere loaded with boric acid in the pores; the porous polymer microsphere is polymerized by acrylate monomer and aliphatic diene crosslinking agent, and the pores are formed by adding a porogen during the polymerization process.

[0042] In some embodiments of the present invention, preferably, the particle size distribution of the removing agent is 0.2 mm to 1.0 mm.

[0043] In some embodiments of the present invention, preferably, the specific surface area of ​​the removing agent is 300 m². 2 / g~400m 2 / g.

[0044] In some embodiments of the present invention, preferably, the average pore size of the remover is 15 nm to 27 nm.

[0045] In some embodiments of the present invention, preferably, the pore volume of the removing agent is 1.5 mL / g to 2.0 mL / g.

[0046] In another aspect, the present invention provides the application of any one of the above-mentioned removal agents in the removal of nonionic surfactants in organic solutions.

[0047] In some embodiments of the present invention, preferably, the removing agent is used for the removal of nonionic surfactants from sulfolane.

[0048] In some embodiments of the present invention, more preferably, the removing agent is used for the removal of nonionic surfactants in sulfolane desulfurization solutions.

[0049] In some embodiments of the present invention, preferably, the selectivity of the remover for nonionic surfactants and sulfolane is >10, more preferably >50.

[0050] In some embodiments of the present invention, nonionic surfactants in organic solutions are preferably removed by immersion or rinsing.

[0051] In some embodiments of the present invention, more preferably, nonionic surfactants in the organic solution are removed by rinsing. Compared with soaking, rinsing can create a larger concentration gradient, i.e., the difference between the concentration of nonionic surfactants in the solution and the concentration of nonionic surfactants on the removing agent, thus resulting in a higher removal rate.

[0052] In some embodiments of the present invention, preferably, the operating parameters for removing nonionic surfactants from organic solutions by rinsing include: ambient temperature and pressure, and a flow rate of the organic solution rinsing agent < 20 BV / h.

[0053] In some embodiments of the present invention, more preferably, the flow rate of the organic solvent rinsing agent is 4 BV / h to 6 BV / h.

[0054] The volume of resin loaded in a resin column is called the bed volume (BV). If the flow rate of the solution through the resin column is 2 BV / h to 4 BV / h, then the volume of solution passing through per hour is 2 to 4 times the resin bed volume. It takes a certain amount of time for nonionic surfactants in the solution to be adsorbed onto the removal agent; if the flow rate is too high, reaching 20 BV / h or higher, the removal rate will be <60%.

[0055] In some embodiments of the present invention, preferably, after the remover is saturated with adsorbed nonionic surfactant, it is regenerated with a weakly polar or moderately polar organic solvent.

[0056] Nonionic surfactant molecules interact more strongly with weakly or moderately polar organic solvent molecules than they interact with boric acid, allowing them to be separated from boric acid and thus desorbed, thereby regenerating the desorbent.

[0057] In some embodiments of the present invention, more preferably, the weakly polar or moderately polar organic solvent is dichloromethane and / or ethyl acetate.

[0058] The beneficial effects of this invention include:

[0059] 1) The desorbent of the present invention has high selectivity for the adsorption of nonionic surfactants and sulfolane, and the selectivity ratio of nonionic surfactants and sulfolane can reach >50, while the selectivity ratio of the prior art is <2;

[0060] 2) The desorbent of the present invention has a removal rate of ≥98% for nonionic surfactants in sulfolane solution, while the removal rate of the prior art is <30%;

[0061] 3) When the desorbent of the present invention is used to remove nonionic surfactants from sulfolane solution, the loss rate of sulfolane is low (<1%).

[0062] 4) When using the desorbent of the present invention to purify the deteriorated sulfolane desulfurization solution, no other reagents need to be added, and no impurities will be introduced into the desulfurization solution.

[0063] The desorbent of this invention can efficiently remove foaming agents from sulfolane desulfurization solutions, preventing problems such as substandard natural gas quality, unstable equipment operation, and shutdowns caused by foaming due to contamination of the desulfurization solution in natural gas purification plants. Furthermore, prior to the successful development of this invention, due to the lack of technology to effectively remove foaming agents from sulfolane desulfurization solutions, contaminated sulfolane desulfurization solutions in purification plants could not be used and had to be replaced with new solvents. The contaminated solution removed from the unit was treated as waste liquid. The waste liquid generated by a single desulfurization unit due to contamination typically reached over 400 tons, because sulfolane desulfurization solutions contain organic matter content of 70% or higher and also contain toxic components such as hydrogen sulfide. The disposal was extremely difficult and costly, placing a significant economic burden and environmental pressure on purification plants. This invention restores the performance of deteriorated sulfolane, which could previously only be used as waste liquid, allowing for continued use. This not only ensures normal production but also solves the problems of solvent consumption and waste liquid disposal, significantly reducing the production costs and environmental pressure on purification plants, resulting in excellent economic and social benefits. Detailed Implementation

[0064] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0065] The key to the technical solution of this invention lies in the design and preparation of a nonionic surfactant remover, wherein the remover is a porous polymer microsphere loaded with boric acid in the pores; the porous polymer microsphere is prepared by suspension copolymerization of acrylate monomer and aliphatic diene crosslinking agent, and a pore-forming agent is added during the polymerization process to form the pores.

[0066] The removal agent of this invention exhibits high selectivity for nonionic surfactants and sulfolane, enabling the removal of nonionic surfactants from desulfurization solutions containing sulfolane. Specifically, the active component boric acid within the pores of the porous polymer microspheres can complex with the introduced nonionic surfactants without complexing with sulfolane, thereby achieving selective adsorption of both and achieving deep removal of nonionic surfactants from sulfolane with a low sulfolane loss rate; simultaneously, it ensures that no new impurities are introduced after the removal of nonionic surfactants from sulfolane.

[0067] Conventional polymeric adsorbents are polymers formed using styrene as a monomer and divinylbenzene as a crosslinking agent. Because sulfolane has a strong affinity for phenyl groups, these adsorbents exhibit strong adsorption of sulfolane. The removal agent of this invention is a polymer prepared using acrylate as a monomer and aliphatic diene as a crosslinking agent; neither the monomer nor the crosslinking agent contains phenyl groups.

[0068] Sulfolane has a weak affinity for alkanes but a strong affinity for aromatics. Therefore, this invention does not choose styrene, a commonly used monomer, but instead uses acrylates. While the ester groups in acrylates have some adsorption capacity for sulfolane, the alkyl groups have a shielding effect on the adsorption of sulfolane by the ester groups. The more carbon atoms in the alkyl group, the greater the shielding effect. However, an excessive number of alkyl groups may generate long polyacrylate segments and linear acrylate homopolymers during polymerization, causing the prepared remover to clump together during use. This invention preferably uses acrylates derived from C1-C5 alcohols, such as methyl acrylate and hexyl acrylate. The number of alkyl groups in hexyl acrylate best balances the two problems mentioned above: a sufficiently strong shielding effect with very weak adsorption of sulfolane, and no clumping of the remover during use. Therefore, the most preferred acrylate monomer in this invention is hexyl acrylate.

[0069] The polymer stripper of this invention selects an aliphatic diene as the crosslinking agent, rather than the conventional phenyl-containing divinylbenzene, because phenyl groups adsorb sulfolane. Preferred dimethacrylate (ethylene glycol dimethacrylate) increases the swelling degree of the copolymer, resulting in a higher interchain distance in the final polymer, which facilitates the penetration of larger molecular weight nonionic surfactants.

[0070] The micropores prepared by the preferred porogens isooctyl alcohol, n-decane, decanol, and 2-ethyl-1-hexanoic acid in this invention have a pore size that is suitable for the subsequent introduction of the active component boric acid, without the pores being too large and weakening the potential energy superposition effect of each plane. Other porogens will either result in a lower loading of the active component boric acid, or lead to weaker adsorption of nonionic surfactants, resulting in the problem that a small amount of adsorbed nonionic surfactants will be desorbed.

[0071] In preparing the porous polymer microspheres, the preferred molar ratio of the acrylate monomer, aliphatic diene crosslinking agent, and porogen is 1:(0.07-0.3):(0.1-0.8). When the amount of crosslinking agent is higher than 0.3, the internal structure of the resulting porous polymer microspheres will be too dense, increasing the shuttle resistance of nonionic surfactant molecules within the microspheres, which is detrimental to both adsorption and desorption during regeneration, resulting in a low removal rate. When the amount of crosslinking agent is lower than 0.07, the resulting porous polymer microspheres will aggregate in the sulfolane desulfurization solution. When the amount of porogen is lower than 0.1, the pore capacity and specific surface area of ​​the resulting porous polymer microspheres are too low, with an adsorption capacity <10 mg / g, which does not meet the usage requirements. When the amount of porogen is higher than 0.8, the porous polymer microspheres will exhibit poor strength and internal pore structure collapse. More preferably, the molar ratio of the acrylate monomer, the aliphatic diene crosslinking agent, and the porogen is 1:(0.1-0.2):(0.5-0.6).

[0072] The particle size distribution of the removal agent prepared by this invention is preferably 0.2 mm to 1.0 mm; the specific surface area is preferably 300 m². 2 / g~400m 2 / g; the average pore size is preferably 15nm to 27nm; the pore volume is preferably 1.5mL / g to 2.0mL / g.

[0073] The specific method for preparing the removal agent includes the following steps:

[0074] Porous polymer microspheres were obtained by suspending and copolymerizing acrylate monomers, aliphatic diene crosslinking agents and pore-forming agents in water.

[0075] The porous polymer microspheres were soaked in a boric acid solution, then filtered out and dried to obtain the removal agent.

[0076] In some specific embodiments, the boric acid solution is preferably a saturated boric acid solution at 80–90°C. A high concentration of boric acid solution is beneficial for boric acid loading, but boric acid has very low solubility in cold water; increasing the temperature can increase its solubility. However, at temperatures above 90°C, the solution tends to boil, which is not conducive to the deposition of boric acid on the microspheres. Therefore, the present invention preferably uses a saturated boric acid solution at 80–90°C.

[0077] In some specific embodiments, the mass ratio of boric acid to porous polymer microspheres is >0.1. Too little boric acid will result in the adsorption capacity of the resulting remover for nonionic surfactants being <10 mg / g, which does not meet the usage requirements. More preferably, the mass ratio of boric acid to porous polymer microspheres is 0.7.

[0078] In some specific embodiments, the soaking time is >0.5 h. More preferably, the soaking time is 5 h to 6 h. When the soaking time is less than 0.5 h, the adsorption capacity of the resulting remover for nonionic surfactants is <10 mg / g, which does not meet the usage requirements. After the soaking time exceeds 6 h, the adsorption capacity of the remover no longer increases.

[0079] In some specific embodiments, the soaking temperature is 50-90°C. At this temperature, the solubility of boric acid is high. Above 90°C, the solution tends to boil, which is not conducive to the deposition of boric acid on the microspheres.

[0080] In some specific embodiments, the drying temperature is 100–165°C, more preferably 120–140°C. At drying temperatures above 165°C, boric acid tends to decompose into metaboric acid. A temperature of 120–140°C ensures drying without decomposing boric acid, and also results in a shorter drying time.

[0081] In some specific embodiments, the suspension copolymerization process usually also includes initiators, dispersants, etc., such as benzoyl peroxide and hydroxyethyl cellulose in the embodiments. The amount added is sufficient to achieve the effect of initiating polymerization and dispersion, and the present invention does not limit this.

[0082] The removal agent of the present invention can be specifically applied to the removal of nonionic surfactants in organic solutions, especially the removal of nonionic surfactants from sulfolane. More specifically, it can be applied to the removal of nonionic surfactants in sulfolane desulfurization solutions. The selectivity of the removal agent for nonionic surfactants and sulfolane can reach >50.

[0083] In some specific embodiments, nonionic surfactants in organic solutions are removed by immersion or rinsing. More preferably, nonionic surfactants in organic solutions are removed by rinsing. Compared with immersion, rinsing can create a larger concentration gradient, i.e., the difference between the concentration of nonionic surfactants in the solution and the concentration of nonionic surfactants on the removing agent, thus resulting in a higher removal rate.

[0084] In some specific embodiments, the operating parameters for removing nonionic surfactants from organic solutions by rinsing include: ambient temperature and pressure, and a flow rate of the organic solution rinsing agent < 20 BV / h. More preferably, the flow rate of the organic solution rinsing agent is 4 BV / h to 6 BV / h.

[0085] The volume of resin loaded in a resin column is called the bed volume (BV). If the flow rate of the solution through the resin column is 2 BV / h to 4 BV / h, then the volume of solution passing through per hour is 2 to 4 times the resin bed volume. It takes a certain amount of time for nonionic surfactants in the solution to be adsorbed onto the removal agent; if the flow rate is too high, reaching 20 BV / h or higher, the removal rate will be <60%.

[0086] Furthermore, after the remover becomes saturated with adsorbed nonionic surfactants, it can be regenerated using a weakly polar or moderately polar organic solvent. The interaction between nonionic surfactant molecules and weakly polar or moderately polar organic solvent molecules is stronger than their interaction with boric acid, allowing them to be separated from boric acid and thus desorbed, achieving regeneration of the remover. Preferably, the weakly polar or moderately polar organic solvent is dichloromethane and / or ethyl acetate.

[0087] In a preferred embodiment of the present invention, the acrylate monomer is hexyl acrylate, the aliphatic diene crosslinking agent is ethylene glycol dimethacrylate, and the pore-forming agent is decane, decanol, or 2-ethyl-1-hexanoic acid.

[0088] Conventional polymer adsorbents are polymers formed using styrene as a monomer and divinylbenzene as a crosslinking agent. Because sulfolane has a strong affinity for phenyl groups, these adsorbents exhibit strong adsorption of sulfolane. The remover of this invention is a polymer prepared using acrylate as a monomer and an aliphatic diene as a crosslinking agent; neither the monomer nor the crosslinking agent contains phenyl groups. While the ester groups in acrylate have some adsorption capacity for sulfolane, the alkyl groups exhibit a shielding effect on the adsorption of sulfolane by the ester groups, and the greater the number of carbon atoms in the alkyl group, the stronger the shielding effect. However, an excessively large number of alkyl groups may generate long polyacrylate segments and linear acrylate homopolymers during the polymerization reaction, causing the prepared remover to agglomerate during use. The number of alkyl groups in the hexyl acrylate molecule can address both of these issues, satisfying the requirement of a sufficiently large shielding effect for weak sulfolane adsorption while preventing the remover from agglomerating during use. Ethylene glycol dimethacrylate, a preferred crosslinking agent, increases the swelling degree of the copolymer, resulting in a larger interchain distance in the final polymer. This not only facilitates the penetration of large molecular weight organic compounds such as surfactants, but also further weakens the polymer's affinity for sulfolane and enhances its affinity for nonionic surfactants due to the long-chain hydrocarbon groups. Using a porogen to create a porous structure allows surfactant molecules to reside within the pores, where the planes interact simultaneously, resulting in a superposition of potential energy and enhancing the interaction between the surfactant and the removal agent. Decane, decanol, and 2-ethyl-1-hexanoic acid are chosen as porogens to ensure the pore size of the prepared porous polymer is suitable for subsequent introduction of the active component without excessively weakening the superposition of potential energy across the planes. Introducing boric acid onto the inner pore surface of the prepared porous polymer allows the oxygen on the polyoxyethylene nonionic surfactant to donate electrons and complex with the boron atoms on the boric acid, while sulfolane cannot complex with it. This achieves selective adsorption of nonionic surfactants from sulfolane.

[0089] The present invention is illustrated below with specific embodiments, wherein all numerical specifications (e.g., temperature, time, concentration, and weight, including ranges for each) are generally approximate values ​​that may be changed in increments of 0.1 or 1.0 (+) or (-). All numerical specifications are to be understood as being preceded by the term "about".

[0090] Examples 1-13

[0091] Examples 1-13: Remover 1-13 were prepared according to the following steps and their performance was tested.

[0092] I. Preparation of the Removal Agent

[0093] 1) Mix the monomer, crosslinking agent and porogen in a molar ratio of 1:0.1:0.5 to obtain mixture 1;

[0094] 2) Mix mixture 1 with benzoyl peroxide at a mass ratio of 100:1 to obtain mixture 2;

[0095] 3) Hydroxyethyl cellulose, sodium chloride, and water are mixed in a mass ratio of 0.6:10:100 to obtain mixture 3;

[0096] 4) Mix mixture 2 and mixture 3 at a ratio of 1:3, turn on the stirrer, heat to 60-90℃ and react for 12 hours, filter out the microspheres, wash with anhydrous ethanol and deionized water 4 times respectively, and finally dry under vacuum at 60℃ for 18 hours.

[0097] 5) Transfer the microspheres to a 70℃ saturated boric acid solution (the mass ratio of boric acid solution to microspheres is 4.2:1, and the boric acid concentration of the 70℃ saturated boric acid solution is 16.7%, which is equivalent to a boric acid to microsphere mass ratio of 0.7:1) and soak for 5 hours. Filter the microspheres and dry them at 130℃ for 5 hours to obtain the removal agent.

[0098] Obtain by following the steps above:

[0099] Remover 1: The monomer, crosslinking agent and porogen used are, in order, hexyl acrylate, ethylene glycol dimethacrylate and 2-ethyl-1-hexanoic acid.

[0100] Remover 2: The monomer, crosslinking agent and porogen used are methyl acrylate, ethylene glycol dimethacrylate and 2-ethyl-1-hexanoic acid, respectively.

[0101] Remover 3: The monomer, crosslinking agent and porogen used are styrene, ethylene glycol dimethacrylate and 2-ethyl-1-hexanoic acid, respectively.

[0102] Remover 4: The monomer, crosslinking agent and porogen used are, in order, hexyl acrylate, divinylbenzene and 2-ethyl-1-hexanoic acid.

[0103] Remover 5: The monomers, crosslinking agents and porogens used are the same as those used in remover 1, namely hexyl acrylate, ethylene glycol dimethacrylate and 2-ethyl-1-hexanoic acid, but the molar ratio is changed to 1:0.35:0.5.

[0104] Remover 6: The monomer, crosslinking agent and porogen used are, in order, hexyl acrylate, ethylene glycol dimethacrylate and isooctanol.

[0105] Remover 7: The monomers, crosslinking agents and porogens used are the same as those used in remover 1, namely hexyl acrylate, ethylene glycol dimethacrylate and 2-ethyl-1-hexanoic acid, but the molar ratio is changed to 1:0.1:0.05.

[0106] Remover 8: Step 5) Change the mass ratio of boric acid to microspheres to 0.05:1.

[0107] Remover 9: In step 5), the soaking time of the microspheres in the 70°C boric acid solution was changed to 0.4 hours.

[0108] Remover 10: Step 5) Change the drying temperature of the microspheres to 166℃.

[0109] Remover 11: The monomer, crosslinking agent and porogen used are, in order, hexyl acrylate, ethylene glycol dimethacrylate and n-decane.

[0110] Remover 12: The monomer, crosslinking agent and porogen used are, in order, hexyl acrylate, ethylene glycol dimethacrylate and decyl alcohol.

[0111] Remover 13: The monomers and crosslinking agents used are hexyl acrylate and ethylene glycol dimethacrylate, respectively, without porogens.

[0112] II. Preparation of sulfolane solution

[0113] The most common nonionic surfactant in natural gas desulfurization solutions is polyoxyethylene alkyl alcohol ether-20. Polyoxyethylene alkyl alcohol ether-20 is added to sulfolane to prepare a sulfolane solution containing 0.4% (mass fraction) of polyoxyethylene alkyl alcohol ether-20.

[0114] III. De-icing Agent Performance Testing

[0115] Remover agents 1-13 and activated carbon were respectively packed into 14 glass columns with an inner diameter of 25 mm, each with a loading amount of 25 g. More than 500 g of the prepared sulfolane solution was injected into the top of each of the 14 glass columns, allowing the solution to flow from top to bottom through the activated carbon or each remover agent at a rate of 4 BV / h. Finally, nitrogen gas was used to blow the activated carbon and remover agents from the top of the glass columns. The sulfolane solution flowing out of the bottom of each glass column was collected and weighed (m). The mass fraction (w) of polyoxyethylene alkyl alcohol ether-20 in the sulfolane solution was determined. The removal rate and selectivity of the nonionic surfactant by the activated carbon and each remover agent were calculated using the following method:

[0116] Removal rate of nonionic surfactants = (0.4% × 500 – w × m) ÷ (0.4% × 500)

[0117] The activated carbon and each stripping agent were washed from top to bottom with 100 mL of ethyl acetate to elute the polyoxyethylene alkyl alcohol ether-20 and sulfolane adsorbed on the activated carbon and each stripping agent. The mass of each of these two substances was determined by multiplying the mass of the eluent by the content of each of these two substances in the eluent.

[0118] Selectivity ratio = Amount of polyoxyethylene alkyl alcohol ether-20 eluted / Amount of sulfolane eluted

[0119] The results of the removal rate and selective adsorption ratio of nonionic surfactants by activated carbon and various removal agents are shown in Table 1.

[0120] Table 1. Removal rate and selectivity of each remover for nonionic surfactants

[0121]

[0122]

[0123] The experimental results shown in Table 1 indicate that removers 3 and 4, prepared using monomers or crosslinking agents containing phenyl groups, not only have a selectivity ratio lower than 2, but also a removal rate of less than 60% for nonionic surfactants. Remover 5, prepared with a molar ratio of crosslinking agent to monomer greater than 0.3, exhibits selective adsorption of nonionic surfactants in sulfolane, with a selectivity ratio of 33.5, much greater than 2, but a removal rate of less than 60%. Removers 7, 8, and 9, prepared with a porogen to monomer mass ratio lower than 0.1, a boric acid to microsphere mass ratio lower than 0.1, and a boric acid soaking time of less than 0.5 hours, all have very low removal rates of less than 20% due to their adsorption capacity of less than 10 mg / g. Remover 10, prepared by changing the microsphere drying temperature to 166℃, also has a low removal rate of less than 40% because boric acid decomposes into metaboric acid.

[0124] Desorbent 2, prepared using methyl acrylate as a monomer, also achieves a removal rate of over 90% and a selectivity greater than 10 (sulfolane loss rate <1%), meeting the requirements for practical production use. However, it does not have the selectivity greater than 50 of the desorbent prepared using the optimal monomer hexyl acrylate. Desorbent 6, prepared using isooctanol as a porogen, has a selectivity of 47.5 and a relatively high removal rate of over 80%, meeting the requirements for practical production use. However, it does not have the removal rate greater than 95% of the desorbent prepared using the optimal porogens n-decane, decanol, and 2-ethyl-1-hexanoic acid. Desorbent 1, prepared under the optimal conditions, exhibits outstanding performance, with a removal rate exceeding 98% and a selectivity greater than 56.

[0125] The particle size, specific surface area, average pore size, and pore volume of the removal agents 1, 2, 6, 11, and 12, which meet the requirements of actual production use, were determined by sieving, BET method, and the results are shown in Table 2.

[0126] Table 2

[0127]

[0128] The results shown in Table 2 indicate that the particle size distribution of the remover prepared under the optimal conditions is (0.2–1.0) mm; and the specific surface area is (300–400) m². 2 / g; average pore size is (15~27)nm, and pore volume is in the range of (1.5~2.0)mL / g.

[0129] Example 14

[0130] This embodiment explores the removal effect of remover 1 on nonionic surfactants at different flow rates.

[0131] The removing agent 1 was filled into six glass columns with an inner diameter of 25 mm, with a filling amount of 25 g in each column. The six glass columns were numbered sequentially as 1. # ~6 # 500g of a sulfolane solution containing 0.4% (mass fraction) polyoxyethylene alkyl alcohol ether-20 was injected into the top of each of the six glass columns. The solution was then allowed to flow from top to bottom through each glass column at a certain flow rate. # ~6 # The flow rates were successively 0.1 BV / h, 2 BV / h, 4 BV / h, 6 BV / h, 7 BV / h, and 20 BV / h. Finally, nitrogen gas was used to blow activated carbon and the removing agent from the top of the glass column. The sulfolane solution flowing out from the bottom of each glass column was collected and weighed (m). The mass fraction (w) of polyoxyethylene alkyl alcohol ether-20 in the sulfolane solution was determined. The removal rate and selectivity of the removing agent for the nonionic surfactant were calculated using the following method:

[0132] Removal rate of nonionic surfactants = (0.4% × 500 – w × m) ÷ (0.4% × 500)

[0133] The removal rates of nonionic surfactants by the remover 1 at different flow rates are shown in Table 3.

[0134] Table 3. Removal rate of nonionic surfactant by remover 1 at different flow rates.

[0135] <![CDATA[1 # Pillar]]> <![CDATA[2 # Pillar]]> <![CDATA[3 # Pillar]]> <![CDATA[4 # Pillar]]> <![CDATA[5 # Pillar]]> <![CDATA[6 # Pillar]]> Solution flow rate 0.1 BV / h 2BV / h 4BV / h 6BV / h 7BV / h 20BV / h Removal rate 83.7％ 98.5％ 98.5％ 98.3％ 93.2％ 59.4％

[0136] The experimental results shown in Table 3 indicate that the removal rates at flow rates of 4 BV / h to 6 BV / h and 2 BV / h are essentially the same, both exceeding 98%. A faster flow rate is preferable as it saves solution treatment time. However, excessively fast flow rates reduce the removal rate due to insufficient contact time; the removal rate drops to 93.2% at 7 BV / h and falls below 60% at 20 BV / h. Conversely, a flow rate as low as 0.1 BV / h, approaching immersion, also results in insufficient removal rates, below 85%. Therefore, a rinsing method with a flow rate of 4 BV / h to 6 BV / h is preferred for treating the solution.

[0137] Example 15

[0138] In this embodiment, different regeneration solutions were used to regenerate the remover, and the removal effect of the regenerated remover on nonionic surfactants was verified.

[0139] 1) Take 2 from Example 14 # Column, 3 #Column, 4 # The columns were regenerated by rinsing with 100 mL of ethanol, dichloromethane, and ethyl acetate, respectively. Then, 500 g of sulfolane solution containing 0.4% (mass fraction) of polyoxyethylene alkyl alcohol ether-20 was injected into the top of each glass column. The flow rate of the solution was 4 BV / h. The removal rate of nonionic surfactant by the remover 1 after regeneration with ethanol, dichloromethane, and ethyl acetate was tested. The results are shown in Table 4.

[0140] Table 4 shows the removal rates of nonionic surfactants by agent 1 after regeneration with different regenerable solutions.

[0141] <![CDATA[2 # Pillar]]> <![CDATA[3 # Pillar]]> <![CDATA[4 # Pillar]]> regenerated liquid ethanol dichloromethane Ethyl acetate Removal rate 56.8％ 98.3％ 98.2％

[0142] The experimental results shown in Table 4 indicate that the removal rate dropped significantly to below 60% after using ethanol regeneration agent 1; however, the removal rate remained above 98% when using dichloromethane and ethyl acetate regeneration agent 1.

[0143] 2) Continue to regenerate columns #3 and #4 by rinsing with 100 mL of dichloromethane and ethyl acetate, respectively. Then, inject 500 g of a sulfolane solution containing 0.4% (mass fraction) polyoxyethylene alkyl alcohol ether-20 into the top of each glass column, at a flow rate of 4 BV / h. Repeat the above operation to test the removal rate of remover 1 after multiple regenerations. The results are shown in Table 5.

[0144] Table 5. Removal rate of nonionic surfactants after multiple regenerations of the removal agent 1.

[0145]

[0146] The experimental results shown in Table 5 indicate that when using remover 1 to remove nonionic surfactants from sulfolane solution, the removal rate can be maintained at over 98% of the initial removal rate after more than 100 saturation and regeneration cycles, demonstrating good stability.

[0147] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a nonionic surfactant remover, wherein, The preparation method includes the following steps: Porous polymer microspheres were obtained by suspending and copolymerizing acrylate monomers, aliphatic diene crosslinking agents, and porogens in water; the molar ratio of the acrylate monomers, aliphatic diene crosslinking agents, and porogens was 1: (0.07~0.3): (0.1~0.8). The porous polymer microspheres were soaked in a boric acid solution, then filtered out and dried to obtain the removal agent. The mass ratio of boric acid to porous polymer microspheres is >0.1; The soaking time is >0.5 h, and the soaking temperature is 50~90℃; The drying temperature is 100~165℃; The structural formula of the acrylate monomer is: R is a C1-C5 alkyl group; or the acrylate monomer hexyl acrylate.

2. The preparation method according to claim 1, wherein, The acrylate monomer is methyl acrylate.

3. The preparation method according to claim 1, wherein, The aliphatic diene crosslinking agent is ethylene glycol dimethacrylate.

4. The preparation method according to claim 1, wherein, The porogen is selected from at least one of isooctyl alcohol, n-decane, decanol, and 2-ethyl-1-hexanoic acid.

5. The preparation method according to claim 1, wherein, The boric acid solution is a saturated boric acid solution at 80~90℃.

6. A nonionic surfactant remover, obtained by the preparation method according to any one of claims 1-5.

7. The removing agent according to claim 6, wherein, The particle size distribution of the removing agent is 0.2 mm to 1.0 mm.

8. The nonionic surfactant remover according to claim 6, wherein, The specific surface area of ​​the removing agent is 300 m². 2 / g ~ 400 m 2 / g.

9. The nonionic surfactant remover according to claim 6, wherein, The average pore size of the remover is 15 nm to 27 nm.

10. The nonionic surfactant remover according to claim 6, wherein, The pore volume of the removing agent is 1.5 mL / g ~ 2.0 mL / g.

11. The use of the remover according to any one of claims 6-10 in the removal of nonionic surfactants in organic solutions.

12. The application according to claim 11, wherein, Remove nonionic surfactants from organic solutions by soaking or rinsing; The operating parameters for removing nonionic surfactants from organic solutions by rinsing include: ambient temperature and pressure, and a flow rate of the organic solution rinsing agent <20 BV / h.

13. The application according to claim 12, wherein, The flow rate of the organic solvent rinsing agent is 4 BV / h ~ 6 BV / h.

14. The application according to claim 12, wherein, After the remover becomes saturated with adsorbed nonionic surfactants, it is regenerated using a weakly polar or moderately polar organic solvent.

15. The application according to claim 14, wherein, The weakly polar or moderately polar organic solvent is dichloromethane and / or ethyl acetate.

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