Low-alkali-consumption neutral treatment process for chlorobenzene chlorination liquid

Abstract

The present application relates to the technical field of fine chemical technology, and particularly relates to a low-alkali-consumption neutral treatment process of chlorobenzene chlorination liquid. The process takes chlorobenzene chlorination liquid as a treatment object and sequentially comprises five steps of vacuum pre-acid removal, interface microdroplet construction and acid absorption, amine phase resorption and triggering delamination, microdroplet analysis and medium recycling, and polishing neutralization. By means of the synergistic construction of the acid-rich microdroplet interface by amphiphilic Janus silica particles and beta-cyclodextrin-polyethyleneimine amphiphilic polymers, the reversible acid absorption of the choline chloride / ethylene glycol deep eutectic solvent and the delamination regulation of the tertiary amine-isopropyl alcohol system, the low-water-consumption migration and efficient efflux of dissolved hydrogen chloride are realized. The method operates under mild temperature and pressure, the acid is mainly output in the form of migration and analysis, and only low-concentration alkali polishing is required at the end, thereby significantly reducing the alkali consumption and salt generation. The obtained product has stable color and low impurities, and is suitable for continuous deacidification and resourceful acid recovery of the chlorobenzene and its chlorinated derivative post-treatment unit.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and in particular to a low-alkali-consumption chlorobenzene chlorination liquid neutralization process. Background Technology

[0002] After the chlorobenzene chlorination process, the process solution often retains a high level of dissolved hydrogen chloride and small amounts of water, metal ions, and polychlorinated byproducts. Insufficient deacidification can easily lead to equipment corrosion, increased color, deactivation of subsequent catalytic or refining units, and amplified side reactions. Existing projects often use direct addition of sodium hydroxide solution for neutralization, which quickly removes acid but results in a large, instantaneous generation of inorganic salts and a high load on saline wastewater. The introduction of strong alkali into the water worsens the system's viscosity and phase behavior, making it easier for emulsion layers and third phases to form, significantly prolonging the stratification time. Salting out and crystallization also promote heat exchange and pipeline blockage, increasing maintenance costs. To reduce salinity, some solutions employ multi-stage water washing or weak alkali washing, but these require higher water volumes and longer retention times, simultaneously increasing energy consumption and wastewater treatment pressure, and still making it difficult to simultaneously achieve deep deacidification and rapid stratification.

[0003] Acid removal by extraction with tertiary amines or ammonium phosphates has been applied in literature and industry, but it is sensitive to viscosity, temperature, and solvent composition windows. Fluctuations in acid load or accumulation of impurities can easily lead to the formation of a third phase, abrupt changes in phase volume, and entrainment losses. If the reabsorption stage is not properly controlled, amine residues can enter the main organic phase, causing odor and color problems. Solvent oxidation, degradation, and regeneration losses increase operating costs. While basic solid adsorbents or alkalized resins can reduce free water, they are easily clogged by high-boiling residues in aromatic and polychlorinated systems, resulting in rapid capacity decay. Regeneration requires strong acids or bases, producing high-salt waste liquid as a byproduct, leading to poor overall environmental performance. Gas stripping or vacuum desorption methods are also used to migrate and dissolve hydrogen chloride. These methods have high requirements for mass transfer area and operational safety, often requiring higher temperatures or deeper vacuums, and carry risks of aromatic hydrocarbon co-distillation losses and synergistic effects of combustible gases and acid mist. When the system contains iron ions, asphaltenes, or small amounts of sulfur chloride, foaming and mist entrainment intensify, making it difficult to maintain a stable separation boundary.

[0004] Deep eutectic solvents and ionic liquids for acid absorption have attracted attention in recent years, but they generally have high viscosity, and mass transfer is more limited when the acid load increases. If they are too miscible with aromatic matrices, subsequent phase separation is difficult, and residual trace functional media will also affect color and odor control. Price and supply stability also restrict large-scale production.

[0005] At the process control level, fluctuations in chlorination reaction load, start-up and shutdown switching, and differences in acidity and impurities from different batches of raw materials make it difficult for traditional constant volume or constant ratio dosing strategies to match transient demands, easily leading to fluctuations between excessive alkalization and insufficient deacidification. Excessive alkalization leads to increased salinity and water content, while insufficient deacidification perpetuates corrosion and side reactions; both amplify energy and chemical consumption in downstream refining. Meanwhile, increasingly stringent environmental regulations and significantly higher discharge standards for saline wastewater and the cost of external solid salt disposal further exacerbate the contradiction between deep deacidification, low-salt discharge, and continuous controllability.

[0006] In summary, existing technologies generally face the following challenges: First, achieving deep deacidification comes at the cost of high alkali consumption and high salt load; second, under low water consumption constraints, emulsification, third phase formation, and phase separation delays are unavoidable; third, the viscosity, activity, and safety margins of the absorption / desorption and recovery units are narrow, resulting in insufficient stability under fluctuating operating conditions; and fourth, low acid resource utilization and high media losses limit overall economic efficiency and sustainability. The industry urgently needs a complete neutral treatment pathway capable of stably transferring and discharging dissolved hydrogen chloride under low water consumption conditions, while simultaneously reducing salt formation, inhibiting emulsification and entrainment, minimizing aromatic component loss, and possessing continuous operation and resource recovery capabilities. Summary of the Invention

[0007] In view of this, the purpose of this invention is to propose a low-alkali-consumption neutral treatment process for chlorobenzene chlorination liquid, which can deeply remove dissolved hydrogen chloride from chlorobenzene chlorination liquid with low water consumption, while significantly reducing alkali consumption and salt discharge, and avoiding quality fluctuations and operational instability caused by emulsification, third phase and aromatic component loss.

[0008] To achieve the above objectives, this invention provides a low-alkali-consumption neutral treatment process for chlorobenzene chlorination solution, comprising the following steps, with the mass M of the chlorobenzene chlorination solution to be treated as the measurement standard:

[0009] S1 Pre-deacidification under reduced pressure: Stir at 40-45℃ and 40-50kPa for 10-20min to allow dissolved hydrogen chloride to escape with low-boiling substances, thus obtaining a pre-deacidified oil phase;

[0010] S2 Interfacial Microdroplet Construction and Acid Adsorption: Amphiphilic Janus silica particles (0.03-0.07 wt% M) were added to the oil phase; simultaneously, a deep eutectic solvent composed of choline chloride and ethylene glycol (0.9-1.6 wt% M) was added; the mixture was sheared at 1200-1800 rpm for 45-90 s; subsequently, an amphiphilic polymer (0.015-0.025 wt% M) was added; the mixture was stirred at 25°C for 60 s and then allowed to stand for 10-20 min to form an acid-rich microdroplet phase.

[0011] S3 Amine Phase Reabsorption and Triggered Separation: Add tertiary amine absorbent solution, the amount of which is 0.6-1.0 wt% M, and stir at 25℃ for 5 min; then add trigger solution, the amount of which is 1.4-2.0 wt% M, and stir at 25℃ for 1.5-3 min, and let stand for 5-8 min to obtain the upper main organic phase and the lower acid-rich microdroplet phase.

[0012] S4 Microdroplet Desorption and Medium Recycling: The lower acid-rich microdroplet phase is desorbed at 43-45℃ and 40-45kPa for 15-18min to obtain an aqueous solution of hydrogen chloride and the deep eutectic solvent is recovered. The recovered deep eutectic solvent is returned to step S2 for recycling.

[0013] S5 Polishing and low-concentration alkali neutralization: Add tertiary amine stock solution to the main organic phase obtained in step S3, the amount added is 0.2-0.4 wt% M, stir at 25℃ for 5-6 min, and let stand for 10-12 min to separate into layers. Discard the lower water / alcohol phase; then add sodium hydroxide aqueous solution with a concentration of 0.8-1.2 wt%, the amount added is 1 wt% M, stir for 5 min, and let stand to separate into layers to obtain the neutralized chlorobenzene chlorination solution.

[0014] Preferably, the chlorobenzene chlorination solution contains chlorobenzene, dichlorobenzene and higher chlorides, and contains dissolved hydrogen chloride and water.

[0015] Preferably, the representative composition of the chlorobenzene chlorination solution is: 95.4 wt% chlorobenzene, 3.2 wt% total dichlorobenzene (1.3 wt% ortho, 1.1 wt% meta, and 0.8 wt% para), 0.8 wt% higher chlorides, 0.18 g / L dissolved hydrogen chloride, 420 mg / kg water, 520 mg / kg non-volatile residue, and 15 mg / kg iron. Its properties are: density at 25°C 1.107 g / mL and dynamic viscosity at 25°C 0.97 mPa·s.

[0016] Preferably, the amphiphilic Janus silica particles are silica nanoparticles with different hydrophilic and hydrophobic properties on both sides of their surface, with an average particle size of 150-250 nm.

[0017] Preferably, the amphiphilic Janus silica particles are modified with methylsilane on one side by a wax masking method, and the reverse side is obtained by grafting glycidoxypropylsilane with polyethyleneimine.

[0018] Preferably, the amphiphilic Janus silica particles are prepared as follows: deionized water and paraffin are mixed, heated to 70°C and stirred to emulsify, silica nanoparticles are added, emulsification is maintained at 70°C for 15 min, and then naturally cooled to 20°C. After filtration and drying, silica-paraffin composite particles with one side shielded by wax are obtained. They are then dispersed in a mixture of anhydrous ethanol and deionized water, and methyltriethoxysilane and glacial acetic acid are added dropwise. The mixture is stirred at 40°C for 180 min, filtered, washed, and dried to remove paraffin. The particles are then added to an emulsion formed by paraffin and deionized water and emulsified at 70°C for 10 min to form reverse shielding. The particles are then dispersed in anhydrous ethanol and deionized water, and γ-glycidoxypropyltrimethoxysilane is added dropwise. The mixture is reacted at 40°C for 120 min, filtered, washed, and then dispersed in deionized water. Branched polyethyleneimine is added, and the mixture is stirred at 60°C for 120 min. After dewaxing and drying, amphiphilic Janus silica particles are obtained.

[0019] The weight ratio of the silica nanoparticles, methyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and branched polyethyleneimine is 20:10:10:5.

[0020] Preferably, the amphiphilic polymer is an amphiphilic polymer with a β-cyclodextrin-polyethyleneimine backbone.

[0021] Preferably, the amphiphilic polymer is prepared by crosslinking polyethyleneimine and β-cyclodextrin under the action of epichlorohydrin, and then introducing hydrophobic side chains through 1-bromooctadecane.

[0022] Preferably, the weight ratio of branched polyethyleneimine, β-cyclodextrin, epichlorohydrin and 1-bromooctadecane in the amphiphilic polymer raw material is 10:5:10:3.

[0023] Preferably, the branched polyethyleneimine has a weight-average molecular weight of 24,000-26,000.

[0024] Preferably, the deep eutectic solvent is composed of choline chloride and ethylene glycol in a molar ratio of 1:1.8-2.2.

[0025] Preferably, the tertiary amine absorbent is composed of trioctylamine, 1-octanol and hydrocarbon diluent, with trioctylamine accounting for 3-6 wt%, 1-octanol accounting for 15-25 wt%, and the balance being C10-C14 isoalkanes.

[0026] Preferably, the triggering fluid is composed of isopropanol and water, with the mass fraction of isopropanol being 25-40 wt%.

[0027] Preferably, the triggering liquid in step S3 is added by spraying to achieve instantaneous reduction of interfacial tension and rapid stratification.

[0028] Preferably, the analytical apparatus in step S4 is a vacuum vessel with stirring or a thin-layer / flash analyzer, and is equipped with a condenser to collect the aqueous hydrogen chloride solution.

[0029] Preferably, the sum of the static contact time in step S2 and the static stratification time in step S3 is 15-28 min.

[0030] Beneficial technical effects:

[0031] Effect 1: Low alkali consumption and low salt load. The system employs a series of pathways including reduced pressure pre-acidification, interfacial directional transfer, reversible acid adsorption, and secondary reabsorption. This ensures that acid is primarily output through migration and desorption, with only low-concentration alkali used for polishing at the end. This results in low neutralization salt formation, consequently reducing the amount of saline wastewater and solid salts to be treated, and minimizing fluctuations during continuous operation.

[0032] Effect 2: Rapid stratification and anti-emulsification. Amphiphilic Janus silica anchors on one side of the oil-microdroplet interface, β-cyclodextrin-polyethyleneimine amphiphilic polymer provides short-term bridging and traction, 1-octanol adjusts the viscosity and activity coefficient of the tertiary amine phase, and isopropanol-water triggering liquid instantaneously changes the interfacial tension, inhibiting the third phase and persistent emulsification, thus achieving stratification with short residence time.

[0033] Effect 3: Highly efficient mass transfer and stable recovery. The eutectic solvent of choline chloride / ethylene glycol provides reversible absorption sites through hydrogen bonds and ion pairs, shortening the cross-interface diffusion path of dissolved hydrogen chloride; a mild thermobaric desorption window avoids thermal runaway and co-evaporation, ensuring stable acid water collection concentration and low media circulation loss.

[0034] Effect 4: Product quality and downstream compatibility. The sequence of tertiary amine reabsorption followed by polishing reduces the entrainment of amines, alcohols, and water, suppresses non-volatile residues and metal ion migration, makes color and odor control easier, prolongs the activity retention time of downstream catalytic and refining units, and minimizes quality fluctuations during start-up and shutdown switching.

[0035] Effect 5: Equipment safety and scalability. The entire process operates under medium and low temperature, medium vacuum and low oxygen conditions, and the risk of co-evaporation of acid mist and combustible gas is controllable; the boundaries of the spray triggering, desorption and recovery units are clear, heat exchange and pipeline scaling are reduced, and it is suitable for modular parallel scale-up of tower / breathing vessel.

[0036] Effect 6: Resource Utilization and Cost Reduction. The acid-rich microdroplet desorption yields directly usable acidic water; the deep eutectic solvent and tertiary amine phase are circulated in a closed loop, resulting in low replenishment of the absorption medium; salting out and crystallization tendencies are reduced, cleaning cycles are lengthened, and overall chemical, energy, and maintenance costs are decreased, optimizing the total life-cycle cost per unit product.

[0037] Effect 7: Simplified operating conditions and control. Pre-deacidification buffers upstream acidity fluctuations, interfacial particles and amphiphilic polymers provide adaptive interfacial regulation, tertiary amine / deep eutectic dual-channel absorption and secondary reabsorption provide redundancy, and the trigger solution ratio can be finely adjusted according to viscosity and acid load, facilitating closed-loop control with a small number of online indicators. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a process flow diagram of the chlorobenzene chlorination liquid neutralization treatment process of the present invention;

[0040] Figure 2 The infrared spectra of silica nanoparticles and amphiphilic Janus silica particles in Example 2 of this invention are shown.

[0041] Figure 3 The image shows the infrared spectrum of the amphiphilic polymer in Example 2 of this invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0043] Example 1

[0044] The composition and properties of the chlorobenzene chlorination solution in this embodiment are as follows:

[0045] Chlorobenzene: 95.4 wt%

[0046] Total dichlorobenzene: 3.2 wt% (ortho 1.3 wt%, meta 1.1 wt%, para 0.8 wt%).

[0047] Higher chloride content: 0.8 wt%

[0048] Dissolved hydrogen chloride: 0.18 g / L;

[0049] Moisture content: 420 mg / kg;

[0050] Non-volatile residue: 520 mg / kg;

[0051] Fe: 15 mg / kg;

[0052] Density at 25℃: 1.107 g / mL;

[0053] Dynamic viscosity at 25℃: 0.97 mPa·s.

[0054] (I) Preparation of amphiphilic Janus silica particles

[0055] (1) In a 1000mL three-necked flask, add 400g of deionized water and 50g of paraffin wax, heat to 70℃ and mechanically stir at 1000rpm to emulsify, add 20g of silica nanoparticles (average particle size about 200nm), maintain emulsification at 70℃ for 15min, then allow to cool naturally to 20℃, filter, and dry at 40℃ for 60min to obtain silica-paraffin composite particles with one side covered by wax.

[0056] (2) The silica-paraffin composite particles from the previous step were dispersed in a mixture of 300g anhydrous ethanol and 30g deionized water. 10g methyltriethoxysilane and 2g glacial acetic acid were added dropwise. The mixture was stirred at 40°C for 180min to complete the hydrolysis-condensation grafting. After filtration, the mixture was washed twice with anhydrous ethanol and dried at 40°C for 120min. Then, it was added to cyclohexane and stirred at 40°C for 30min to remove the paraffin. After filtration, it was added to an emulsion formed by 150g paraffin and 400g deionized water and emulsified at 70°C for 10min to form... The mixture was reverse-masked and redispersed in 300g anhydrous ethanol and 30g deionized water. 10g γ-glycidoxypropyltrimethoxysilane was added dropwise, and the mixture was reacted at 40°C for 120min. After filtration, the mixture was washed with ethanol and redispersed in 100g deionized water. 5g branched polyethyleneimine (Sigma-Aldrich, weight average molecular weight approximately 25,000, catalog number P434400) was added, and the mixture was stirred at 60°C for 120min. Finally, the mixture was dewaxed with cyclohexane and dried at 40°C for 720min to obtain amphiphilic Janus silica particles.

[0057] (II) Preparation of Amphiphilic Polymers

[0058] In a 250 mL flask, 10 g of branched polyethyleneimine (Sigma-Aldrich, weight-average molecular weight approximately 25,000, catalog number P434400) and 5 g of β-cyclodextrin were dissolved in 100 g of deionized water. 10 g of epichlorohydrin was added dropwise under ice bath conditions, and the mixture was stirred at 25 °C for 180 min to obtain an aqueous solution of β-cyclodextrin and polyethyleneimine. Then, 3 g of 1-bromooctadecane and 50 g of anhydrous ethanol were added, and the mixture was stirred at 45 °C for 120 min. The mixture was then dried under vacuum at 60 °C for 720 min to obtain an amphiphilic polymer.

[0059] (III) Configuration of the absorption / trigger system

[0060] In a 200 mL beaker, add 140 g of choline chloride and 124 g of ethylene glycol, stir at 80 °C for 30 min until transparent, then cool to 25 °C to obtain a deep eutectic solvent; in a 500 mL beaker, add 20 g of trioctylamine, 100 g of 1-octanol and 400 g of hydrocarbon diluent (ExxonMobil Exxsol D80), stir at 25 °C for 10 min to obtain a tertiary amine absorption solution; in a 500 mL beaker, mix 41 g of isopropanol and 99 g of deionized water to obtain a triggering solution;

[0061] (iv) Neutralization treatment of chlorobenzene chlorination solution

[0062] 10,000 g of chlorobenzene chlorination solution was placed in a vacuum vessel with a stirrer, and the pressure was reduced to 50 kPa at 40 °C and stirred for 10 min to remove low-boiling hydrogen chloride gas, resulting in a pre-deacidified oil phase. Then, 3 g of amphiphilic Janus silica particles and 90 g of deep eutectic solvent were added, and the mixture was sheared at 1200 rpm for 45 s. Subsequently, 1.5 g of amphiphilic polymer was added and stirred uniformly for 60 s, followed by standing at 25 °C for 10 min to complete microdroplet acid enrichment. Next, 60 g of tertiary amine absorbent was added, and the mixture was stirred at 25 °C for 5 min. Finally, 140 g of triggering liquid was sprayed uniformly using a sprayer, and the mixture was stirred at 25 °C for 1.5 min, followed by 5 min of further processing. After standing for 10 minutes, the mixture separates into two layers: an upper layer consisting of a main organic phase and a lower layer consisting of acid-rich microdroplets. The lower acid-rich microdroplet phase is introduced into a vacuum vessel and desorbed at 43°C and 45 kPa for 15 minutes. The upper condensate is collected as an aqueous solution of hydrogen chloride, and the lower part is collected as a regenerated deep eutectic solvent, which can be directly recycled. 20 g of tertiary amine stock solution is added to the main organic phase and stirred at 25°C for 5 minutes to remove trace amounts of residual hydrogen chloride complexes. After standing for 10 minutes, the mixture separates into two layers. The lower layer containing a small amount of water / alcohol is discarded. Then, 100 g of 0.8 wt% sodium hydroxide solution is added. After standing for 5 minutes, the mixture separates into two layers. The lower layer is discarded to obtain the treated solution.

[0063] Example 2:

[0064] The composition and properties of the chlorobenzene chlorination solution in this embodiment are as follows:

[0065] Chlorobenzene: 95.4 wt%

[0066] Total dichlorobenzene: 3.2 wt% (ortho 1.3 wt%, meta 1.1 wt%, para 0.8 wt%).

[0067] Higher chloride content: 0.8 wt%

[0068] Dissolved hydrogen chloride: 0.18 g / L;

[0069] Moisture content: 420 mg / kg;

[0070] Non-volatile residue: 520 mg / kg;

[0071] Fe: 15 mg / kg;

[0072] Density at 25℃: 1.107 g / mL;

[0073] Dynamic viscosity at 25℃: 0.97 mPa·s.

[0074] (I) Preparation of amphiphilic Janus silica particles

[0075] (1) In a 1000mL three-necked flask, add 400g of deionized water and 50g of paraffin wax, heat to 70℃ and mechanically stir at 1000rpm to emulsify, add 20g of silica nanoparticles (average particle size about 200nm), maintain emulsification at 70℃ for 15min, then allow to cool naturally to 20℃, filter, and dry at 40℃ for 60min to obtain silica-paraffin composite particles with one side covered by wax.

[0076] (2) The silica-paraffin composite particles from the previous step were dispersed in a mixture of 300g anhydrous ethanol and 30g deionized water. 10g methyltriethoxysilane and 2g glacial acetic acid were added dropwise. The mixture was stirred at 40°C for 180min to complete the hydrolysis-condensation grafting. After filtration, the mixture was washed twice with anhydrous ethanol and dried at 40°C for 120min. Then, it was added to cyclohexane and stirred at 40°C for 30min to remove the paraffin. After filtration, it was added to an emulsion formed by 150g paraffin and 400g deionized water and emulsified at 70°C for 10min to form... The mixture was reverse-masked and redispersed in 300g anhydrous ethanol and 30g deionized water. 10g of γ-glycidoxypropyltrimethoxysilane was added dropwise, and the mixture was reacted at 40°C for 120min. After filtration, the mixture was washed with ethanol and redispersed in 100g deionized water. 5g of branched polyethyleneimine (Sigma-Aldrich, weight average molecular weight approximately 25,000, catalog number P434400) was added, and the mixture was stirred at 60°C for 120min. Finally, the mixture was dewaxed with cyclohexane and dried at 40°C for 720min to obtain amphiphilic Janus silica particles.

[0077] (II) Preparation of Amphiphilic Polymers

[0078] In a 250 mL flask, 10 g of branched polyethyleneimine (Sigma-Aldrich, weight-average molecular weight approximately 25,000, catalog number P434400) and 5 g of β-cyclodextrin were dissolved in 100 g of deionized water. 10 g of epichlorohydrin was added dropwise under ice bath conditions, and the mixture was stirred at 25 °C for 180 min to obtain an aqueous solution of β-cyclodextrin-polyethyleneimine. Then, 3 g of 1-bromooctadecane and 50 g of anhydrous ethanol were added, and the mixture was stirred at 45 °C for 120 min. The mixture was then dried under vacuum at 60 °C for 720 min to obtain an amphiphilic polymer.

[0079] (III) Configuration of the absorption / trigger system

[0080] In a 200 mL beaker, add 140 g of choline chloride and 124 g of ethylene glycol, stir at 80 °C for 30 min until transparent, then cool to 25 °C to obtain a deep eutectic solvent; in a 500 mL beaker, add 20 g of trioctylamine, 100 g of 1-octanol and 400 g of hydrocarbon diluent (ExxonMobil Exxsol D80), stir at 25 °C for 10 min to obtain a tertiary amine absorption solution; in a 500 mL beaker, mix 50 g of isopropanol and 120 g of deionized water to obtain a triggering solution;

[0081] (iv) Neutralization treatment of chlorobenzene chlorination solution

[0082] 10,000 g of chlorobenzene chlorination solution was placed in a vacuum vessel with a stirrer, and the pressure was reduced to 50 kPa at 40°C and stirred for 15 min to remove low-boiling hydrogen chloride gas, resulting in a pre-deacidified oil phase. Then, 5 g of amphiphilic Janus silica particles and 120 g of deep eutectic solvent were added, and the mixture was sheared at 1500 rpm for 60 s. Next, 2 g of amphiphilic polymer was added and stirred uniformly for 60 s, followed by standing at 25°C for 15 min to complete microdroplet acid enrichment. Then, 80 g of tertiary amine absorbent was added and stirred at 25°C for 5 min. Finally, 170 g of triggering liquid was sprayed uniformly using a sprayer, and the mixture was stirred at 25°C for 2 min and 5 min. After settling, the mixture was allowed to separate into layers, forming an upper layer consisting of a main organic phase and a lower layer consisting of acid-rich microdroplets. The lower acid-rich microdroplet phase was introduced into a vacuum vessel and desorbed at 45°C and 40 kPa for 15 min. The upper condensate was collected as an aqueous solution of hydrogen chloride, and the lower part was collected as a regenerated deep eutectic solvent, which was directly recycled. 30 g of tertiary amine stock solution was added to the main organic phase and stirred at 25°C for 5 min to remove trace amounts of residual hydrogen chloride complexes. After settling for 10 min, the mixture separated into layers. The lower layer containing a small amount of water / alcohol was discarded. Then, 100 g of 1 wt% sodium hydroxide solution was added, and after 5 min, the mixture was allowed to separate into layers. The lower layer was discarded to obtain the treated solution.

[0083] Example 3:

[0084] The composition and properties of the chlorobenzene chlorination solution in this embodiment are as follows:

[0085] Chlorobenzene: 95.4 wt%

[0086] Total dichlorobenzene: 3.2 wt% (ortho 1.3 wt%, meta 1.1 wt%, para 0.8 wt%).

[0087] Higher chloride content: 0.8 wt%

[0088] Dissolved hydrogen chloride: 0.18 g / L;

[0089] Moisture content: 420 mg / kg;

[0090] Non-volatile residue: 520 mg / kg;

[0091] Fe: 15 mg / kg;

[0092] Density at 25℃: 1.107 g / mL;

[0093] Dynamic viscosity at 25℃: 0.97 mPa·s.

[0094] (I) Preparation of amphiphilic Janus silica particles

[0095] (1) In a 1000mL three-necked flask, add 400g of deionized water and 50g of paraffin wax, heat to 70℃ and mechanically stir at 1000rpm to emulsify, add 20g of silica nanoparticles (average particle size about 200nm), maintain emulsification at 70℃ for 15min, then allow to cool naturally to 20℃, filter, and dry at 40℃ for 60min to obtain silica-paraffin composite particles with one side covered by wax.

[0096] (2) The silica-paraffin composite particles from the previous step were dispersed in a mixture of 300g anhydrous ethanol and 30g deionized water. 10g methyltriethoxysilane and 2g glacial acetic acid were added dropwise. The mixture was stirred at 40°C for 180min to complete the hydrolysis-condensation grafting. After filtration, the mixture was washed twice with anhydrous ethanol and dried at 40°C for 120min. Then, it was added to cyclohexane and stirred at 40°C for 30min to remove the paraffin. After filtration, it was added to an emulsion formed by 150g paraffin and 400g deionized water and emulsified at 70°C for 10min to form... The mixture was reverse-masked and redispersed in 300g anhydrous ethanol and 30g deionized water. 10g γ-glycidoxypropyltrimethoxysilane was added dropwise, and the mixture was reacted at 40°C for 120min. After filtration, the mixture was washed with ethanol and redispersed in 100g deionized water. 5g branched polyethyleneimine (Sigma-Aldrich, weight average molecular weight approximately 25,000, catalog number P434400) was added, and the mixture was stirred at 60°C for 120min. Finally, the mixture was dewaxed with cyclohexane and dried at 40°C for 720min to obtain amphiphilic Janus silica particles.

[0097] (II) Preparation of Amphiphilic Polymers

[0098] In a 250 mL flask, 10 g of branched polyethyleneimine (Sigma-Aldrich, weight-average molecular weight approximately 25,000, catalog number P434400) and 5 g of β-cyclodextrin were dissolved in 100 g of deionized water. 10 g of epichlorohydrin was added dropwise under ice bath conditions, and the mixture was stirred at 25 °C for 180 min to obtain an aqueous solution of β-cyclodextrin and polyethyleneimine. Then, 3 g of 1-bromooctadecane and 50 g of anhydrous ethanol were added, and the mixture was stirred at 45 °C for 120 min. The mixture was then dried under vacuum at 60 °C for 720 min to obtain an amphiphilic polymer.

[0099] (III) Configuration of the absorption / trigger system

[0100] In a 200 mL beaker, add 140 g of choline chloride and 124 g of ethylene glycol, stir at 80 °C for 30 min until transparent, then cool to 25 °C to obtain a deep eutectic solvent; in a 500 mL beaker, add 20 g of trioctylamine, 100 g of 1-octanol and 400 g of hydrocarbon diluent (ExxonMobil Exxsol D80), stir at 25 °C for 10 min to obtain a tertiary amine absorption solution; in a 500 mL beaker, mix 59 g of isopropanol and 141 g of deionized water to obtain a triggering solution;

[0101] (iv) Neutralization treatment of chlorobenzene chlorination solution

[0102] 10,000 g of chlorobenzene chlorination solution was placed in a vacuum vessel with a stirrer, and the pressure was reduced to 40 kPa at 45°C and stirred for 20 min to remove low-boiling hydrogen chloride gas, resulting in a pre-deacidified oil phase. Then, 7 g of amphiphilic Janus silica particles and 160 g of deep eutectic solvent were added, and the mixture was sheared at 1800 rpm for 90 s. Subsequently, 2.5 g of amphiphilic polymer was added and stirred uniformly for 60 s, followed by standing at 25°C for 20 min to complete microdroplet acid enrichment. Then, 100 g of tertiary amine absorbent was added and stirred at 25°C for 5 min. Finally, 200 g of triggering liquid was sprayed uniformly using a sprayer, and the mixture was stirred at 25°C for 3 min, followed by 8 min of further processing. After standing for 12 minutes, the liquid was allowed to separate into two layers: an upper layer consisting of a main organic phase and a lower layer consisting of acid-rich microdroplets. The lower acid-rich microdroplet phase was introduced into a vacuum vessel and desorbed at 45°C and 40 kPa for 18 minutes. The upper condensate was collected as an aqueous solution of hydrogen chloride, and the lower part was collected as a regenerated deep eutectic solvent, which was directly recycled. 40 g of tertiary amine stock solution was added to the main organic phase and stirred at 25°C for 6 minutes to remove trace amounts of residual hydrogen chloride complexes. After standing for 12 minutes, the liquid was allowed to separate into two layers. The lower layer containing a small amount of water / alcohol was discarded. Then, 100 g of 1.2 wt% sodium hydroxide solution was added. After standing for 5 minutes, the liquid was allowed to separate into two layers. The lower layer was discarded to obtain the treated liquid.

[0103] Comparative Example 1:

[0104] The difference between Comparative Example 1 and Example 2 is that the pre-deacidification and depressurization step (evacuation to 50 kPa at 40°C and stirring for 15 min to remove low-boiling hydrogen chloride gas) is not performed, while the other conditions are the same as in Example 2.

[0105] Comparative Example 2:

[0106] The difference between Comparative Example 2 and Example 2 is that no amphiphilic Janus silica particles were added, while the other conditions were the same as in Example 2.

[0107] Comparative Example 3:

[0108] The difference between Comparative Example 3 and Example 2 is that no amphiphilic polymer was added, while the other conditions were the same as in Example 2;

[0109] Comparative Example 4:

[0110] The difference between Comparative Example 4 and Example 2 is that no eutectic solvent (choline chloride and ethylene glycol system) is added, while the other conditions are the same as in Example 2;

[0111] Comparative Example 5:

[0112] The difference between Comparative Example 5 and Example 2 is that 1-octanol is not added to the tertiary amine absorption solution (it is prepared only with trioctylamine and hydrocarbon diluents), while the other conditions are the same as in Example 2.

[0113] Comparative Example 6:

[0114] The difference between Comparative Example 6 and Example 2 is that the analytical pressure was changed to 60 kPa (analyzing at 45°C for 15 min), while the other conditions were the same as in Example 2.

[0115] Comparative Example 7:

[0116] The difference between Comparative Example 7 and Example 2 is that the main organic phase is not replenished with tertiary amine stock solution, while the other conditions are the same as in Example 2.

[0117] Performance testing:

[0118] The infrared spectrum was characterized using Fourier transform infrared spectroscopy, and the results are shown in Table 2.

[0119] Composition and content: Qualitative and quantitative analysis was performed according to GB / T 9722-2023; volatile components such as chlorobenzene and dichlorobenzene were determined by flame ionization detector and quantified by external standard method. The results are shown in Table 1.

[0120] Residual dissolved hydrogen chloride: Following the principle of HJ 549-2016, inert gas bubbling was used to carry the dissolved hydrogen chloride in the treatment solution to the absorption solution. The chloride ion concentration in the absorption solution was determined by ion chromatography and converted into the mass concentration of hydrogen chloride. The results are shown in Table 1.

[0121] Moisture content: Referring to GB / T 6324.8-2014, the Karl Fischer coulometric method was used, and the results are shown in Table 1.

[0122] Non-volatile residue (dry residue): determined according to GB / T 6324.2-2004, the results are shown in Table 1.

[0123] Acid-rich droplet particle size distribution: The acid-rich droplet phase was inertly diluted and then the D10 / D50 / D90 were measured by laser diffraction.

[0124] Table 1 Performance Test Results

[0125] sample Chlorobenzene / wt% Total dichlorobenzene (wt%) Residual dissolved hydrogen chloride / mg / L Moisture / mg / kg Non-volatile residue / mg / kg Acid-rich microdroplets D50 / μm Regenerated hydrogen chloride concentration / mol / L Example 1 95.4 3.2 2.2 460 510 12.8 6.1 Example 2 95.4 3.2 1.8 440 500 9.6 6.4 Example 3 95.3 3.2 2.4 490 520 8.4 5.9 Comparative Example 1 95.4 3.2 4.5 470 515 13.5 5.6 Comparative Example 2 95.3 3.2 4.9 500 540 28.0 4.8 Comparative Example 3 95.4 3.2 4.2 480 525 16.5 5.3 Comparative Example 4 95.3 3.2 4.7 505 560 — 3.4 Comparative Example 5 95.3 3.2 4.6 495 545 20.5 5.0 Comparative Example 6 95.4 3.2 3.2 450 505 9.6 5.7 Comparative Example 7 95.4 3.2 3.6 455 512 9.7 6.0

[0126] Data Analysis:

[0127] As can be seen from the data of Examples 1-3 in Table 1, the sequential combination of pre-deacidification, Janus silica-oriented construction of acid-rich microdroplets, reversible acid adsorption and tertiary amine reabsorption by deep eutectic solvent, alcohol-water atomization triggering, and gentle desorption keeps the dissolved hydrogen chloride in the treatment solution at a low level, controls the moisture and non-volatile residues, reduces the median particle size of the acid-rich microdroplets, and keeps the concentration of regenerable hydrogen chloride in a suitable range, thus meeting the goals of low salt load and recyclable treatment. This may be due to the following reasons: Janus silica achieves unilateral anchoring at the oil-droplet interface, shortening the cross-interface diffusion path of hydrogen chloride; the deep eutectic solvent provides reversible absorption sites through hydrogen bonds and ion pairs, avoiding the mass transfer lag caused by traditional bulk phase absorption; the branched polyethyleneimine-cyclodextrin-alkyl amphiphilic polymer bridges the droplets and hydrophilic surfaces within a short time window, promoting polymerization and stratification; the tertiary amine phase is diluted with low aromatic hydrocarbons and supplemented with a small amount of 1-octanol to adjust viscosity and activity coefficient, reducing mass transfer resistance and suppressing the third phase; the atomization trigger and the set resolution window of vapor-liquid equilibrium together achieve efficient regeneration and acid recovery under low water usage conditions, forming a three-phase synergistic system of interface orientation, reversible absorption, and phase behavior regulation.

[0128] Comparative Example 1 showed increased residual dissolved hydrogen chloride, coarsening of acid-rich droplets, decreased hydrogen chloride recovery concentration, and unfavorable conditions for moisture and non-volatile residues. This is because omitting pre-deacidification resulted in a high initial acid load and insufficient driving force, leading to partial occupation of the subsequent absorption-desorption window, making it difficult for the droplet phase to complete effective enrichment and stratification in a short time.

[0129] Comparative Example 2 showed a significant increase in residual dissolved hydrogen chloride, a significant coarsening of acid-rich droplets, and a decrease in acid recovery concentration. This was mainly due to the disappearance of interfacial orientation and unilateral anchoring effects after the absence of Janus silica, resulting in a decrease in droplet stability and effective interfacial area, limited transfacial flux, and a reduced stratification rate.

[0130] Comparative Example 3 showed an increase in residual dissolved hydrogen chloride, an increase in the size of acid-rich droplets, and a decrease in acid recovery concentration. This was mainly due to the absence of amphiphilic polymers, which caused the disappearance of short-term bridging and traction effects. As a result, droplets could not approach the hydrophilic surface to complete rapid aggregation, and the interfacial migration and stratification dynamics were hindered. This further illustrates that the superposition of short-term bridging and directional enrichment produces a 1+1 greater than 2 effect.

[0131] Comparative Example 4 showed an increase in residual dissolved hydrogen chloride, a significant decrease in acid recovery concentration, and difficulty in effectively measuring acid-rich droplets. This is mainly because the absence of the deep eutectic solvent leaves the system with no reversible absorption sites, and the single tertiary amine phase pathway cannot simultaneously achieve both low water consumption and efficient desorption, resulting in limitations on both phase behavior and regeneration efficiency.

[0132] Comparative Example 5 showed an increase in residual dissolved hydrogen chloride, an increase in the particle size of acid-rich droplets, and a decrease in acid recovery concentration. This may be due to the mismatch between viscosity and solubility parameters after the tertiary amine phase lacks 1-octanol, resulting in higher interfacial tension, limited mass transfer and complexation migration, prolonged separation time, and the induction of unfavorable phase states.

[0133] Comparative Example 6 showed an increase in residual dissolved hydrogen chloride, a decrease in acid recovery concentration, and no significant change in droplet size. This is mainly because the increased desorption pressure weakened the vapor-liquid equilibrium driving force, resulting in incomplete desorption.

[0134] Comparative Example 7 showed an increase in residual dissolved hydrogen chloride, a decrease in regenerated hydrogen chloride concentration, and a relatively unchanged median droplet size for acid-rich microdroplets, while moisture and non-volatile residues were slightly higher. This was because the main organic phase did not undergo a second replenishment of the tertiary amine stock solution. After the first round of mass transfer, the activity and effective basicity of the reabsorption phase decreased, leading to a partial interruption of the deep eutectic-tertiary amine alternating chain. This weakened the driving force for subsequent atomization triggering and desorption, resulting in incomplete desorption of hydrogen chloride from the microdroplets to the tertiary amine phase. The accumulated acid load prolonged the stratification time and amplified the terminal alkali treatment load. Simultaneously, the lack of replenishment prevented the viscosity and activity coefficient of the tertiary amine phase from being within their optimal range. Increased interfacial tension and limited interfacial flux together led to a decrease in the regenerable acid concentration.

[0135] from Figure 2 It can be seen that Janus silica, compared to unmodified silica, has a lower content of 2956 / 2925 / 2854 cm⁻¹. -1 Significant CH stretching and contraction occurred at 1450 / 1375cm. -1 CH deformation occurred, and at 1260, 910, and 840 cm -1 CN / epoxy residual signal appears; simultaneously, the Si-O-Si main band increases from approximately 1100 cm⁻¹. -1 Expanded and split into 1090 and 1125 cm -1 acromion, 800 and 460cm -1 The skeletal band is still there.

[0136] from Figure 3 It can be seen that the amphiphilic polymer exhibits a broad OH / NH band (≈3300 cm⁻¹). -1 ), strong CH (2920 / 2850cm) -1 ), CN (1248cm) -1 ) and β-cyclodextrin COC (1150 / 1080 / 1028cm) -1 ), indicating successful alkylation and cyclodextrin grafting.

[0137] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A low-alkali-consumption neutral treatment process for chlorobenzene chlorination liquid, characterized in that, The steps include the following, with the mass M of the chlorobenzene chlorination solution to be treated as the measurement standard: S1 Pre-deacidification under reduced pressure: Stir at 40-45℃ and 40-50kPa for 10-20min to allow dissolved hydrogen chloride to escape with low-boiling substances, thus obtaining a pre-deacidified oil phase; S2 Interfacial Microdroplet Construction and Acid Adsorption: Amphiphilic Janus silica particles (0.03-0.07 wt% M) were added to the oil phase; simultaneously, a deep eutectic solvent composed of choline chloride and ethylene glycol (0.9-1.6 wt% M) was added; the mixture was sheared at 1200-1800 rpm for 45-90 s; subsequently, an amphiphilic polymer (0.015-0.025 wt% M) was added; the mixture was stirred at 25°C for 60 s and then allowed to stand for 10-20 min to form an acid-rich microdroplet phase. S3 Amine Phase Reabsorption and Triggered Separation: Add tertiary amine absorbent solution, the amount of which is 0.6-1.0 wt% M, and stir at 25℃ for 5 min; then add trigger solution, the amount of which is 1.4-2.0 wt% M, and stir at 25℃ for 1.5-3 min, and let stand for 5-8 min to obtain the upper main organic phase and the lower acid-rich microdroplet phase. S4 Microdroplet Desorption and Medium Recycling: The lower acid-rich microdroplet phase is desorbed at 43-45℃ and 40-45kPa for 15-18min to obtain an aqueous solution of hydrogen chloride and the deep eutectic solvent is recovered. The recovered deep eutectic solvent is returned to step S2 for recycling. S5 Polishing and Low-Concentration Alkali Neutralization: Add tertiary amine stock solution (0.2-0.4 wt% M) to the main organic phase obtained in step S3, stir at 25°C for 5-6 min, and let stand for 10-12 min to separate the phases. Discard the lower water / alcohol phase. Then add 0.8-1.2 wt% sodium hydroxide aqueous solution (1 wt% M), stir for 5 min, and let stand to separate the phases to obtain a neutralized chlorobenzene chlorination solution. The tertiary amine absorbent is composed of trioctylamine, 1-octanol and hydrocarbon diluent, with trioctylamine accounting for 3-6 wt%, 1-octanol accounting for 15-25 wt%, and the balance being C10-C14 isoalkanes; the triggering solution is composed of isopropanol and water, with isopropanol having a mass fraction of 25-40 wt%.

2. The low-alkali-consumption chlorobenzene chlorination liquid neutralization treatment process according to claim 1, characterized in that, The chlorobenzene chlorination solution contains chlorobenzene, dichlorobenzene and higher chlorides, and contains dissolved hydrogen chloride and water.

3. The low-alkali-consumption chlorobenzene chlorination liquid neutralization treatment process according to claim 1, characterized in that, The amphiphilic Janus silica particles were modified with methylsilane on one side by a wax masking method, and then grafted onto polyethyleneimine on the other side with glycidoxypropylsilane; the weight-average molecular weight of the polyethyleneimine was 24,000-26,000.

4. The low-alkali-consumption chlorobenzene chlorination liquid neutralization treatment process according to claim 1, characterized in that, The amphiphilic Janus silica particles were prepared as follows: Deionized water and paraffin were mixed, heated to 70°C, and emulsified by stirring. Silica nanoparticles were added, and the mixture was kept at 70°C for 15 minutes of emulsification, then naturally cooled to 20°C. The mixture was filtered and dried to obtain silica-paraffin composite particles with one side shielded by paraffin. These particles were then dispersed in a mixture of anhydrous ethanol and deionized water, and methyltriethoxysilane and glacial acetic acid were added dropwise. The mixture was stirred at 40°C for 180 minutes, filtered, washed, and dried to remove the paraffin. Subsequently, the mixture was added to an emulsion formed from paraffin and deionized water. In the emulsion, emulsification was carried out at 70°C for 10 min to form a reverse shielding, and then dispersed in anhydrous ethanol and deionized water. γ-glycidoxypropyltrimethoxysilane was added dropwise, and the reaction was carried out at 40°C for 120 min. After filtration and washing, the mixture was dispersed in deionized water, and polyethyleneimine was added. The mixture was stirred at 60°C for 120 min, dewaxed, and dried to obtain amphiphilic Janus silica particles. The weight ratio of the silica nanoparticles, methyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and polyethyleneimine was 20:10:10:

5.

5. The low-alkali-consumption chlorobenzene chlorination liquid neutralization treatment process according to claim 1, characterized in that, The amphiphilic polymer is prepared by crosslinking polyethyleneimine and β-cyclodextrin under the action of epichlorohydrin, and then introducing hydrophobic side chains through 1-bromooctadecane; the weight average molecular weight of the polyethyleneimine is 24,000-26,000.

6. The low-alkali-consumption chlorobenzene chlorination liquid neutralization treatment process according to claim 5, characterized in that, The weight ratio of polyethyleneimine, β-cyclodextrin, epichlorohydrin, and 1-bromooctadecane in the amphiphilic polymer raw material is 10:5:10:

3.

7. The low-alkali-consumption chlorobenzene chlorination liquid neutralization treatment process according to claim 1, characterized in that, The deep eutectic solvent is composed of choline chloride and ethylene glycol in a molar ratio of 1:1.8-2.

2.

8. The low-alkali-consumption chlorobenzene chlorination liquid neutralization treatment process according to claim 1, characterized in that, The triggering liquid mentioned in step S3 is added by spraying to achieve instantaneous reduction of interfacial tension and rapid stratification.

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