Method for preparing high-performance heavy alkyl benzene sulfonic acid barium salt by modifying heavy alkyl benzene raw material

Abstract

The embodiment of the invention provides a method for preparing high-performance heavy alkyl benzene sulfonic acid barium salt by modifying a heavy alkyl benzene raw material, and relates to the technical field of synthesis of lubricating oil additives. The method for preparing the high-performance heavy alkyl benzene sulfonic acid barium salt by modifying the heavy alkyl benzene raw material comprises the following steps: S1, selecting narrow-fraction long-straight-chain alpha-olefin with the carbon number range of C10-C14 as an alkylating agent, and carrying out Friedel-Crafts alkylation reaction on the alkylating agent and benzene in the presence of a Lewis acid catalyst at the reaction temperature of 30-70 DEG C according to the molar ratio of the benzene to the alpha-olefin of 3: 1-8: 1; the reaction time is 1-4 hours, and after the reaction is completed, carrying out hydrolysis, layering and distillation purification; by physically mixing the narrow-fraction long-straight-chain alpha-olefin synthesized heavy alkylbenzene with regular structure and low branching degree with commercially available heavy alkylbenzene, the molecular homogeneity of the raw material is optimized, the reaction consistency and the salifying stability are improved on the premise of not changing the existing process, and the barium heavy alkylbenzene sulfonate product with better damp-heat and salt spray performance is prepared.

Description

Technical Field

[0001] This application relates to the field of lubricant additive synthesis technology, and more specifically, to a method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials. Background Technology

[0002] Barium heavy alkylbenzene sulfonate is an important type of oil-soluble rust inhibitor, widely used in rust-preventive oils, greases and compound additives, and plays a key role in the long-term protection of metal parts in harsh environments such as humidity and salt spray.

[0003] However, most commercially available heavy alkylbenzenes are produced by alkylation of aromatic hydrocarbons and mixed olefins from refineries. The raw material sources are complex, and the products are mixtures with wide carbon chain distribution, high branching degree, and numerous isomers, resulting in heterogeneous molecular structures. Barium sulfonate salts prepared from such heavy alkylbenzenes exhibit large differences in reactivity during sulfonation, and the substitution positions are uncontrollable. After salt formation, the molecular arrangement is disordered, making it difficult to form a stable and continuous protective film. Therefore, commercially available barium sulfonate salts generally suffer from large batch performance fluctuations, difficulty in achieving stable performance beyond 76 hours in damp heat tests, and generally less than 24 hours in salt spray tests. They are unable to meet the requirements of high-end applications for long-term rust prevention performance. In particular, the damp heat stability and salt spray corrosion resistance exhibit large batch-to-batch fluctuations and unstable performance, making it difficult to meet the requirements of high-end industrial fields for long-term and reliable rust prevention performance.

[0004] Existing technologies mainly focus on optimizing sulfonation or salt formation process parameters, such as adjusting temperature, acid ratio, and neutralization method, but they do not fundamentally solve the performance bottleneck caused by defects in the raw material structure. It is difficult to improve the molecular regularity and structural consistency of the main sulfonation raw material (heavy alkylbenzene) from the source, resulting in poor stability and protective performance of barium sulfonate products. Summary of the Invention

[0005] The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to the embodiments of this application includes the following steps: S1. Narrow-fraction long straight-chain α-olefins with a carbon number range of C10 to C14 are selected as alkylating agents and reacted with benzene in the presence of Lewis acid catalysts via Friedel-Crafts alkylation. The reaction temperature is 30 to 70 °C, the molar ratio of benzene to α-olefin is 3:1 to 8:1, and the reaction time is 1 to 4 hours. After the reaction is completed, the product is purified by hydrolysis, layering, and distillation to obtain a stable component, heavy alkylbenzene, with a regular structure, low branching degree, and carbon chain length distribution concentrated in the range of ±2 carbon atoms. S2. The stable component heavy alkylbenzene obtained in step S1 is physically mixed with at least one commercially available heavy alkylbenzene in a mass ratio, wherein the amount of the stable component heavy alkylbenzene added is 30% to 60% of the total mass of the mixture, and 5% base oil is added as a diluent as needed. The mixture is stirred evenly to form a modified heavy alkylbenzene raw material. S3. Take the modified heavy alkylbenzene raw material obtained in step S2, and slowly add fuming sulfuric acid at 30-50°C to carry out sulfonation reaction. Control the molar ratio of sulfur trioxide to total alkylbenzene to be 1.05:1 to 1.15:1, and maintain the reaction time for 1.5 to 3 hours until sulfonation is complete. S4. The sulfonated product obtained in step S3 is washed with water to remove unreacted acidic substances and byproducts until the aqueous phase is neutral, thus obtaining a pure alkylbenzene sulfonic acid intermediate. S5. Add a 10%–20% sodium hydroxide aqueous solution to the alkylbenzene sulfonic acid intermediate obtained in step S4, and stir and neutralize at 40–60°C until the pH value is 6.5–7.5 to generate the corresponding sodium heavy alkylbenzene sulfonate. S6. Add a soluble barium salt solution to the sodium salt system obtained in step S5, and carry out a metathesis reaction at 70-90°C for 2-4 hours to completely replace sodium ions with barium ions and form barium salt colloid of heavy alkylbenzene sulfonate. S7. The reaction product obtained in step S6 is subjected to dehydration, solvent removal, filtration and drying to remove moisture and residual solvent, and the final barium heavy alkylbenzene sulfonate product is obtained.

[0006] Furthermore, in step S1, the Lewis acid catalyst is selected from at least one of aluminum trichloride, hydrogen fluoride, and supported solid acid. After the reaction is completed, the reaction is terminated by hydrolysis, the organic phase is separated by layering, and purified by vacuum distillation to obtain a product with a difference between the initial boiling point and the dry point not exceeding 25°C and a density of 0.86–0.89 g / cm³. 3 Refractive index nD 20 The stable component is heavy alkylbenzene with a content of 1.475 to 1.485.

[0007] Furthermore, in step S1, the molar ratio of benzene to α-olefin in the Friedel-Crafts alkylation reaction is 4:1 to 6:1, the reaction temperature is 40 to 60°C, the reaction time is 2 to 3 hours, and the proportion of linear alkylbenzene isomers with 2-phenyldodecane structure in the obtained stable component heavy alkylbenzene product is higher than 85%, and the degree of branching is lower than 15%.

[0008] Furthermore, in step S2, the commercially available heavy alkylbenzene is selected from one of the following three types: The first heavy alkylbenzene is derived from the alkylation product of C10-C14 α-olefins and benzene, which are byproducts of ethylene oligomerization; The second heavy alkylbenzene is derived from the alkylation byproducts of C9-C10 aromatics and C8-C10 mixed olefins in refineries; The third heavy alkylbenzene is a mixture of industrial-grade alkylbenzenes obtained by reacting C8-C12 inner olefins with benzene under an acidic catalyst.

[0009] Furthermore, in step S2, the amount of the stabilizing component heavy alkylbenzene added is 45% of the total mass of the mixed system, and the amount of the base oil added is 5% of the total mass of the modified heavy alkylbenzene raw material.

[0010] Furthermore, in step S2, the physical mixing is carried out in a jacketed temperature-controlled stirred tank, with the mixing temperature maintained at 40-60°C, the stirring rate at 200-400 rpm, and the mixing time at 30-90 minutes. After mixing, no chemical reaction or separation operation is performed, and the mixture is directly used in the subsequent sulfonation step.

[0011] Furthermore, in step S3, the sulfonating agent is liquid sulfur trioxide, which is slowly introduced into the reaction system using nitrogen gas. The molar ratio of sulfur trioxide to total alkylbenzene is 1.10:1, the reaction temperature is controlled at 35-45°C, and the reaction time is maintained for 2 hours.

[0012] Furthermore, in step S5, the neutralization process uses a 15% sodium hydroxide aqueous solution, and the reaction is stirred at 50-55°C for 30-60 minutes, with the pH value controlled at 7.0±0.3, to generate a sodium heavy alkylbenzene sulfonate intermediate.

[0013] Furthermore, in step S6, the soluble barium salt is an aqueous solution of barium acetate with a concentration of 10-20 wt%. The metathesis reaction is carried out under stirring at 80-85°C for 3 hours until the sodium ion concentration in the system is below 50 ppm, thus completing the complete replacement of barium ions.

[0014] Furthermore, in step S7, the dehydration process adopts vacuum dehydration at a temperature of 90-110°C and a pressure of less than or equal to 0.09 MPa. After solvent removal, the insoluble matter is removed by plate and frame filtration. The resulting filter cake is dried at 80-100°C for 4-8 hours to obtain a barium heavy alkylbenzene sulfonate product with good flowability.

[0015] The beneficial effects of this application are as follows: By introducing a stable component, heavy alkylbenzene, synthesized from narrow-fraction long-chain α-olefins, which has the characteristics of concentrated carbon chain distribution, low branching degree, and regular structure, the molecular uniformity of the raw materials is effectively improved. The stable component heavy alkylbenzene is physically mixed with commercially available heavy alkylbenzene in a specific ratio, which not only retains the compatibility of the original process but also improves the reaction consistency of the mixed raw materials. In the subsequent sulfonation, neutralization, and barium salting processes, due to the more regular structure of the raw materials, the substitution position of the sulfonic acid groups is more controllable, which is conducive to the formation of structurally stable barium sulfonate colloids. The final product can build a denser and continuous hydrophobic protective film on the metal surface, thus maintaining excellent rust prevention performance in high humidity and high chloride ion environments. This method does not require modification of existing production equipment; product quality can be upgraded simply by controlling the premixing of raw materials. It has the advantages of simple process, good repeatability, and easy large-scale production. It can stably prepare heavy alkylbenzene barium sulfonate products with better wet heat and salt spray performance, meeting the performance requirements of high-end rust-preventive lubricating oils and greases.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of the overall steps according to an embodiment of this application; Figure 2 This is a flowchart illustrating the preparation of the stable component, heavy alkylbenzene, according to embodiments of this application. Figure 3 This is a flowchart illustrating the preparation of modified heavy alkylbenzene feedstock according to embodiments of this application; Figure 4 This is a flowchart illustrating the preparation of barium salt heavy alkylbenzene sulfonate colloids according to embodiments of this application; Figure 5 This is a flowchart illustrating the preparation process of barium sulfonate salt product according to an embodiment of this application. Detailed Implementation

[0019] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0020] The following describes, with reference to the accompanying drawings, a method for preparing high-performance barium alkylbenzene sulfonate salt by modifying heavy alkylbenzene raw materials according to embodiments of this application.

[0021] like Figures 1-5 As shown, the method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to the embodiments of this application includes the following steps: S1. Preparation of stable component heavy alkylbenzene First, a stable heavy alkylbenzene component with a highly regular structure, low branching degree, and concentrated carbon chain distribution is synthesized via Friedel-Crafts alkylation reaction. This heavy alkylbenzene serves as the core component for subsequent modification. The consistency of the molecular structure of this stable heavy alkylbenzene component is fundamental to improving the performance of the final barium sulfonate product. The specific operation is as follows: Narrow-fraction long straight-chain α-olefins with a carbon number range of C10 to C14 are selected as alkylating agents. High-purity raw materials with C12 as the main component (i.e., twelve-carbon α-olefins, containing small amounts of C11 and C13) are preferred, with a purity of not less than 95% and a boiling range of less than 15℃. This ensures that the carbon chain length is concentrated and the double bond position is clear (located at the end of the molecule), which is conducive to the formation of alkylbenzene products with high linearity.

[0022] The α-olefin was subjected to a liquid-phase Friedel-Crafts alkylation reaction with benzene in the presence of a Lewis acid catalyst, wherein benzene not only served as a reactant but also as a solvent, playing a role in dilution and temperature control.

[0023] The Lewis acid catalyst is selected from at least one of aluminum trichloride (AlCl3), hydrogen fluoride (HF), or supported solid acid. When aluminum trichloride is used, its amount is usually 5% to 15% of the mass of the α-olefin. The moisture content of the reaction system must be strictly controlled to prevent catalyst deactivation.

[0024] During the reaction, the molar ratio of benzene to α-olefin is controlled between 3:1 and 8:1, preferably 4:1 to 6:1. Under this ratio, the occurrence of polyalkylation side reactions can be effectively suppressed and the selectivity of monoalkylbenzene can be improved. The reaction temperature is set at 30 to 70°C, preferably 40 to 60°C, and the reaction time is maintained at 1 to 4 hours, preferably 2 to 3 hours. Under these mild conditions, the reaction can be carried out stably and isomerization or polymerization side reactions caused by high temperature can be avoided.

[0025] After the reaction is complete, deionized water is slowly added to the system for hydrolysis treatment, which deactivates the Lewis acid catalyst and converts it into a water-soluble substance. Then, the system is allowed to stand and separate into layers, and the upper organic phase is separated. The organic phase is purified by vacuum distillation to remove unreacted benzene and light components. The target fraction is collected to obtain a heavy alkylbenzene product with a difference between the initial boiling point and the dry point not exceeding 25°C.

[0026] Gas chromatography analysis confirmed that the carbon chain length distribution of the obtained product was concentrated within ±2 carbon atoms (i.e., mainly distributed between C10 and C14, with C12 having the highest proportion), and the density was 0.86–0.89 g / cm³. 3 (20℃), refractive index nD 20 The value ranged from 1.475 to 1.485, indicating that the composition was uniform and the impurity content was low. Further analysis by 1H NMR and mass spectrometry revealed that the linear alkylbenzene isomers with the 2-phenyldodecane structure accounted for more than 85% of the product, with the remainder being small amounts of 3-phenyl and 4-phenyl substituted products. The total branching degree was less than 15% (based on the proportion of branched alkyl substitution), exhibiting excellent molecular regularity and high linearity.

[0027] The stable component, heavy alkylbenzene, has the characteristics of consistent reactive sites and high sulfonation selectivity, providing a structural template for subsequent mixing and modification with commercially available heavy alkylbenzene, and improving the overall uniformity of raw materials and the controllability of the reaction.

[0028] S2, forming modified heavy alkylbenzene raw materials The stable component heavy alkylbenzene with regular structure, low branching degree and concentrated carbon chain distribution obtained in step S1 is physically mixed with at least one commercially available heavy alkylbenzene in a predetermined mass ratio to construct a modified heavy alkylbenzene raw material system with excellent reaction consistency and molecular uniformity.

[0029] The amount of the stabilizing component heavy alkylbenzene added is 30% to 60% of the total mass of the mixed system, preferably 45%. Within this range, it can effectively improve the overall structural regularity of the raw materials while taking into account cost control and process adaptability. When the amount of the stabilizing component heavy alkylbenzene added is less than 30%, its regulatory effect on the highly branched and widely distributed components in commercially available heavy alkylbenzene is limited, making it difficult to improve the rust prevention performance of the subsequent barium sulfonate. When the amount added exceeds 60%, although the performance continues to improve, the marginal benefits decrease and the economy declines.

[0030] The commercially available heavy alkylbenzenes selected include, but are not limited to, one of the following three typical industrial sources: The first heavy alkylbenzene is derived from the alkylation reaction of C10-C14 α-olefins, a byproduct of ethylene oligomerization, with benzene under Lewis acid catalysis. It has an average carbon number of about C12.5, a light color, and a certain degree of branching structure.

[0031] The second heavy alkylbenzene is a byproduct obtained from the alkylation reaction of C9-C10 aromatics and C8-C10 mixed olefins by-products of refineries. It has a high impurity content, contains a certain amount of short-chain alkyl substitutes and polycyclic aromatics, and has low initial rust prevention performance.

[0032] The third heavy alkylbenzene is an industrial-grade mixture of alkylbenzenes produced by the reaction of C8-C12 inner olefins (i.e., olefins with double bonds located inside the carbon chain) with benzene under the action of acidic catalysts (such as HF or AlCl3). It has a complex structure, many isomers, poor linearity, and poor batch stability.

[0033] The aforementioned commercially available heavy alkylbenzenes can all be purchased from the domestic market and represent the typical characteristics of current mainstream industrial raw materials. In order to improve the fluidity during the mixing process and promote the uniform dispersion of components, base oil not exceeding 5% of the total mass of the mixture can be added to the mixing system as a diluent as needed. The base oil can be selected from mineral base oil (such as 150SN, 500SN), synthetic hydrocarbon oil (PAO) or light solvent oil (such as 120# or 200# solvent oil). 120# solvent oil is preferred because it has moderate volatility, good solubility and does not affect the subsequent reaction process.

[0034] The mixing operation is carried out in a stainless steel mixing vessel equipped with a jacketed temperature control system and a mechanical stirring device. The mixing temperature is maintained between 40 and 60°C. This temperature range helps to reduce the viscosity of the system and improve the mass transfer efficiency, while avoiding thermal oxidation reactions caused by high temperature. The stirring rate is controlled within the range of 200 to 400 rpm to ensure that the components are fully sheared and dispersed without generating excessive foam.

[0035] The mixing time is set to 30-90 minutes, preferably 60 minutes, until no stratification or obvious concentration gradient is observed visually, resulting in a modified heavy alkylbenzene raw material with uniform appearance and good flowability. The entire mixing process is only physical blending and does not involve any chemical reaction, phase change or separation and purification operations. Therefore, no additional reactor or distillation equipment is required, and it is compatible with existing production processes.

[0036] After mixing, the resulting modified raw material can be directly transported to the next process for sulfonation reaction without storage or intermediate processing, reducing the risk of contamination and performance fluctuations caused by material transfer. The core advantage of this step is that by introducing a stable component with high linearity and narrow distribution, heavy alkylbenzene component, "structural compensation" is performed on the branching, short chain and non-ideal structure present in commercially available heavy alkylbenzene, thereby improving the overall molecular regularity and reaction consistency of the raw material, providing a more uniform distribution of active sites for subsequent sulfonation reaction, and ultimately facilitating the production of barium heavy alkylbenzene sulfonate products with stable structure and excellent colloidal properties.

[0037] Step S3: Sulfonation reaction of modified heavy alkylbenzenes The modified heavy alkylbenzene raw material obtained in step S2 is transferred to a sulfonation reactor equipped with a mechanical stirrer, thermometer, gas inlet pipe, and cooling coil, and sulfonation reaction is carried out under temperature control. The initial reaction temperature is controlled between 30 and 50°C, preferably 35 to 45°C. Within this temperature range, the reaction proceeds smoothly and side reactions (such as polysulfonation, oxidation, or coking) are effectively suppressed. Fuming sulfuric acid (containing 20% ​​to 30% SO3) or liquid sulfur trioxide (SO3) can be used as the sulfonating agent. However, in order to improve reaction selectivity, reduce waste acid generation, and improve product purity, this invention preferably uses high-purity liquid sulfur trioxide as the sulfonating agent. The liquid SO3 is slowly introduced into the reaction system by nitrogen gas carrying. After drying, the nitrogen gas is stably delivered as SO3 vapor at a flow rate of 0.3 to 0.8 L / min to achieve uniform gas-liquid dispersion and avoid excessive local concentration that could lead to violent exothermic reactions or carbonization. The molar ratio of sulfur trioxide to total alkylbenzene should be controlled at 1.05:1 to 1.15:1, preferably 1.10:1. This ratio ensures that the alkylbenzene is essentially completely sulfonated while avoiding side reactions caused by excessive SO3 or increased burden on subsequent water washing. The SO3 introduction rate should be slow and steady, typically completed within 1.5 to 3.0 hours, preferably within 2 hours. The reaction temperature should be continuously monitored during the addition process, and jacket cooling should be used to maintain temperature stability if necessary. After the addition is complete, the reaction should be continued with stirring and heat preservation within the same temperature range for 1.5 to 3 hours, preferably 2 hours, to ensure complete sulfonation. The reaction endpoint can be determined by sampling to measure the free acid value or by detecting the characteristic peak of the benzene ring (1180 cm⁻¹) using Fourier transform infrared spectroscopy (FT-IR). -1 The presence of an S=O asymmetric stretching vibration peak indicates this. The resulting sulfonation product is a viscous alkylbenzene sulfonic acid, ranging in color from light brown to dark brown, with no obvious coking particles, indicating a homogeneous and well-controlled reaction. The key advantage of this step is that, since the previous step optimized the homogeneity of the raw material molecules by introducing a structurally regular and stable heavy alkylbenzene component, resulting in high linearity of the alkyl chain and concentrated substitution positions, the reactive sites are uniformly distributed during sulfonation, mainly generating para- or ortho-monosulfonic acid products, significantly improving sulfonation selectivity and product purity. Simultaneously, using nitrogen-carried liquid SO3 instead of traditional fuming sulfuric acid not only reduces moisture introduction and waste acid emissions but also improves reaction efficiency and environmental friendliness, which is beneficial for improving the quality of subsequent salt formation.

[0038] Step S4: Water washing treatment of sulfonated products The sulfonated product obtained in step S3 is transferred to a washing tank and washed with water to remove unreacted acidic substances (such as residual SO3 and H2SO4), byproducts (such as sulfone compounds), and other water-soluble impurities. The specific operation is as follows: Add deionized water to the reaction system in batches, each batch containing 10%–20% of the mass of the sulfonated product. Stir while adding water at a speed of 200–300 rpm to prevent emulsification or uneven stratification. After each batch of water is added, raise the temperature to 40–50°C and maintain the temperature while stirring for 10–15 minutes to promote the separation of the acid phase and the organic phase. Then allow the mixture to stand and settle for 30–60 minutes. Once clear stratification is achieved, open the drain valve to release the lower acid-aqueous phase.

[0039] Repeat the washing process as described above until the aqueous phase after the last wash is neutral (pH value of 6.5-7.5, measured with precision pH test paper or pH meter) and the conductivity is less than 50 μS / cm, indicating that the residual acid has been basically removed. The entire washing process usually needs to be carried out 4-6 times, and the total water consumption is about 60%-100% of the raw material mass.

[0040] Finally, the upper organic phase is retained, which is the pure alkylbenzene sulfonic acid intermediate. Its appearance is a uniform transparent or slightly turbid brownish-yellow liquid with no irritating acid mist. It can be used for subsequent neutralization reactions. The core function of this step is to thoroughly remove the strong acid components to prevent them from corroding the subsequent neutralization and salt formation equipment, while avoiding residual acid catalytic side reactions that would cause the product to darken in color or decrease in colloidal stability.

[0041] In addition, thorough rinsing can remove some polar impurities, improve the oil solubility and storage stability of the final barium sulfonate. This invention particularly emphasizes that the endpoint of rinsing is "neutral aqueous phase" rather than a fixed number of washes, in order to ensure the consistency of treatment effects between different batches and guarantee stable product quality.

[0042] Step S5: Neutralization reaction generates sodium heavy alkylbenzene sulfonate intermediate. The purified alkylbenzene sulfonic acid intermediate obtained in step S4 is transferred to a neutralization reactor. A sodium hydroxide aqueous solution is added under stirring to neutralize the intermediate, generating the corresponding sodium heavy alkylbenzene sulfonate salt. The mass fraction of the sodium hydroxide aqueous solution is controlled between 10% and 20%, preferably 15%. This concentration ensures good fluidity and dispersibility of the alkali solution while avoiding excessively high local alkali concentrations that could trigger saponification side reactions or generate excessive heat leading to a sudden rise in system temperature. The neutralization process is carried out at a mild temperature of 40–60°C, preferably 50–55°C. Temperature control can be achieved through jacket heating or a warm water circulation system to prevent increased viscosity due to low temperatures affecting mass transfer, or molecular degradation due to high temperatures. The alkali solution is added slowly dropwise at a rate of 1%–2% of the total alkali added per minute, while continuously stirring at a rate of 200–300 rpm to ensure uniform reaction and controllable exothermic response. The pH value of the system is monitored in real time. Alkali addition is stopped when the pH reaches 6.5–7.5, with the final pH preferably controlled at 7.0 ± 0.3, indicating that the sulfonic acid groups have been almost completely converted to sodium salt form. After alkali addition, the reaction is continued at the same temperature with stirring for 30–60 minutes, preferably 45 minutes, to ensure complete neutralization and form a homogeneous and stable sodium heavy alkylbenzene sulfonate brine-oil mixture. The resulting intermediate is a milky white to light yellow gel-like liquid with no free acid odor and good stability. The key advantage of this step is that by precisely controlling the alkali concentration, feeding rate, and reaction temperature, a mild and controllable neutralization process is achieved, effectively avoiding carbonization, color deepening, or demulsification caused by localized over-alkali. Simultaneously, the generated sodium sulfonate intermediate serves as a precursor for subsequent metathesis reactions, and its structural integrity directly affects the gelling properties and oil solubility of the final barium salt. Therefore, this invention particularly emphasizes pH control precision and reaction uniformity, laying the foundation for efficient barium ion replacement.

[0043] Step S6: Preparation of barium salt colloid of heavy alkylbenzenesulfonate by metathesis reaction A soluble barium salt solution is added to the sodium heavy alkylbenzene sulfonate intermediate system obtained in step S5, and a metathesis reaction is carried out under heating and stirring conditions to completely replace sodium ions with barium ions, generating barium heavy alkylbenzene sulfonate colloid.

[0044] The preferred soluble barium salt is barium acetate, with an aqueous solution concentration of 10-20 wt%, preferably 15%. Other soluble barium salts such as barium chloride can also be used, but barium acetate is more advantageous due to its good solubility, mild reaction, and low tendency to form barium sulfate precipitate. Deionized water is used to prepare the barium salt solution. After stirring until completely dissolved, the solution is filtered through a 0.45 μm filter membrane to remove insoluble matter and prevent the introduction of impurities that could affect the purity of the product.

[0045] The barium salt solution is slowly added to the sodium salt system described above. During the addition process, the stirring rate is maintained at 250-400 rpm to promote sufficient ion exchange. The reaction temperature is controlled between 70-90°C, preferably 80-85°C. Within this temperature range, it is beneficial to improve the ion migration rate and reaction kinetics, and shorten the reaction time. The reaction time is maintained at 2-4 hours, preferably 3 hours. During this period, the change in sodium ion concentration in the system is continuously monitored. After sampling, the sodium ion concentration is analyzed by flame photometry or ion chromatography. When the sodium ion concentration is below 50 ppm, it is determined that the barium ion replacement is complete and the reaction ends.

[0046] After the reaction is complete, the system exhibits a typical colloidal state, appearing as a milky white to pale yellow translucent gel with moderate fluidity, indicating the formation of a stable barium heavy alkylbenzene sulfonate micelle structure. The core function of this step is to convert the water-soluble sodium salt into the oil-soluble barium salt through a metathesis reaction, giving the product excellent metal surface adsorption capacity and rust prevention properties. The use of barium acetate not only results in high reaction efficiency, but also produces sodium acetate as a byproduct, which is easily soluble in water and facilitates subsequent separation. The high-temperature reaction helps to disrupt the original sodium salt lattice structure, promotes barium ion penetration and replacement, and increases the salt formation rate.

[0047] This invention specifically emphasizes using "sodium ion concentration below 50 ppm" as the criterion for judging the reaction endpoint, rather than a fixed reaction time, in order to ensure the consistency of product quality between different batches and avoid loss of active ingredients or decline in rust prevention performance due to incomplete reaction.

[0048] Step S7: Post-processing to obtain the finished barium heavy alkylbenzenesulfonate salt. The colloidal reaction product of barium heavy alkylbenzene sulfonate obtained in step S6 is post-processed by sequentially passing through dehydration, desolventization, filtration and drying processes to remove moisture, residual solvent and insoluble impurities from the system, and finally obtain a high-purity barium heavy alkylbenzene sulfonate product with good flowability.

[0049] First, dehydration is performed: the gel-like product after the reaction is completed is transferred to a dehydration vessel equipped with a stirrer and a vacuum interface, the jacket heating system is turned on, and the temperature is gradually raised to 90-110℃. At the same time, the vacuum pump is started to reduce the pressure of the reaction system to ≤0.09MPa. Under negative pressure, free water and residual low-boiling-point solvents (such as water in incompletely removed benzene, solvent oil or sodium acetate solution) are continuously distilled off.

[0050] During the dehydration process, maintain a stirring speed of 150-250 rpm to enhance heat and mass transfer efficiency and prevent local overheating that could lead to product charring or damage to the colloidal structure. The dehydration time is usually 2-4 hours, until there is no obvious liquid distillation from the condenser and the viscosity of the material tends to stabilize, at which point the moisture is considered to have been basically removed.

[0051] The solvent removal process is then carried out. If base oil or solvent oil was used as a diluent in the previous step, the processing time is appropriately extended or the temperature is slightly increased (not exceeding 110°C) under the same vacuum conditions to further remove residual organic solvents and ensure that the volatile content in the final product is less than 1.0%.

[0052] After solvent removal, the material is cooled to below 70°C and transferred to a plate and frame filter press for solid-liquid separation. The preferred filter membrane material is polypropylene or nylon filter cloth, with a filtration accuracy of 5-10 μm, to effectively trap trace amounts of insoluble particles that may be generated during the reaction. The resulting filter cake is a uniform and dense paste.

[0053] Transfer the filter cake to a stainless steel tray, spreading it evenly with a thickness not exceeding 3cm. Place it in an electric heating drying oven for final drying. The drying temperature is controlled at 80-100℃, preferably 90℃, and the drying time is maintained at 4-8 hours, preferably 6 hours. Under these conditions, the bound water in the micropores can be fully removed without causing product decomposition or color darkening.

[0054] After drying, the material is removed and allowed to cool naturally to room temperature to obtain a powder or paste-like barium heavy alkylbenzene sulfonate product with a milky white to light yellow appearance, uniform texture, no lumps, and good flowability. This product has excellent oil solubility and can be directly used in the formulation of metal protective materials such as rust-preventive oils and lubricating greases.

[0055] To verify the universality and performance improvement effect of the method of the present invention, three commercially available heavy alkylbenzenes from different sources were selected and mixed with the stable component heavy alkylbenzenes prepared in the present invention in different proportions. These three commercially available heavy alkylbenzenes can be the heavy alkylbenzenes described above, added at a weight ratio of 30%-60%, and mixed with the three different commercially available heavy alkylbenzenes. After subsequent processing, barium salt of heavy alkylbenzene sulfonate was obtained. The optimal ratio was determined by measuring the damp heat and salt spray performance. The specific ratios are shown in the table below: Mixture of No. 1 heavy alkylbenzene

[0056] Mixture of No. 2 heavy alkylbenzene

[0057] Mixture of three heavy alkylbenzenes

[0058] Based on the data from the three tables above, adding different proportions of the stabilizing component heavy alkylbenzene can ensure both wet heat performance and significantly improve salt spray performance.

[0059] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0060] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials, characterized in that, Includes the following steps: S1. Narrow-fraction long straight-chain α-olefins with a carbon number range of C10 to C14 are selected as alkylating agents and reacted with benzene in the presence of Lewis acid catalysts via Friedel-Crafts alkylation. The reaction temperature is 30 to 70 °C, the molar ratio of benzene to α-olefin is 3:1 to 8:1, and the reaction time is 1 to 4 hours. After the reaction is completed, the product is purified by hydrolysis, layering, and distillation to obtain a stable component, heavy alkylbenzene, with a regular structure, low branching degree, and carbon chain length distribution concentrated in the range of ±2 carbon atoms. S2. The stable component heavy alkylbenzene obtained in step S1 is physically mixed with at least one commercially available heavy alkylbenzene in a mass ratio, wherein the amount of the stable component heavy alkylbenzene added is 30% to 60% of the total mass of the mixture, and 5% base oil is added as a diluent as needed. The mixture is stirred evenly to form a modified heavy alkylbenzene raw material. S3. Take the modified heavy alkylbenzene raw material obtained in step S2, and slowly add fuming sulfuric acid at 30-50°C to carry out sulfonation reaction. Control the molar ratio of sulfur trioxide to total alkylbenzene to be 1.05:1 to 1.15:1, and maintain the reaction time for 1.5 to 3 hours until sulfonation is complete. S4. The sulfonated product obtained in step S3 is washed with water to remove unreacted acidic substances and byproducts until the aqueous phase is neutral, thus obtaining a pure alkylbenzene sulfonic acid intermediate. S5. Add a 10%–20% sodium hydroxide aqueous solution to the alkylbenzene sulfonic acid intermediate obtained in step S4, and stir and neutralize at 40–60°C until the pH value is 6.5–7.5 to generate the corresponding sodium heavy alkylbenzene sulfonate. S6. Add a soluble barium salt solution to the sodium salt system obtained in step S5, and carry out a metathesis reaction at 70-90°C for 2-4 hours to completely replace sodium ions with barium ions and form barium salt colloid of heavy alkylbenzene sulfonate. S7. The reaction product obtained in step S6 is subjected to dehydration, solvent removal, filtration and drying to remove moisture and residual solvent, and the final barium heavy alkylbenzene sulfonate product is obtained.

2. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 1, characterized in that, In step S1, the Lewis acid catalyst is selected from at least one of aluminum trichloride, hydrogen fluoride, and supported solid acid. After the reaction is completed, the reaction is terminated by hydrolysis. The organic phase is separated by layering and purified by vacuum distillation to obtain a product with a difference between the initial boiling point and the dry point not exceeding 25°C and a density of 0.86–0.89 g / cm³. 3 Refractive index nD 20 The stable component is heavy alkylbenzene with a content of 1.475 to 1.

485.

3. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 2, characterized in that, In step S1, the molar ratio of benzene to α-olefin in the Friedel-Crafts alkylation reaction is 4:1 to 6:1, the reaction temperature is 40 to 60°C, and the reaction time is 2 to 3 hours. The resulting stable heavy alkylbenzene product contains linear alkylbenzene isomers with a 2-phenyldodecane structure accounting for more than 85% and has a branching degree of less than 15%.

4. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 1, characterized in that, In step S2, the commercially available heavy alkylbenzene is selected from one of the following three types: The first heavy alkylbenzene is derived from the alkylation product of C10-C14 α-olefins and benzene, which are byproducts of ethylene oligomerization; The second heavy alkylbenzene is derived from the alkylation byproducts of C9-C10 aromatics and C8-C10 mixed olefins in refineries; The third heavy alkylbenzene is a mixture of industrial-grade alkylbenzenes obtained by reacting C8-C12 inner olefins with benzene under an acidic catalyst.

5. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 4, characterized in that, In step S2, the amount of the stabilizing component heavy alkylbenzene added is 45% of the total mass of the mixed system, and the amount of the base oil added is 5% of the total mass of the modified heavy alkylbenzene raw material.

6. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 5, characterized in that, In step S2, the physical mixing is carried out in a jacketed temperature-controlled stirred tank, with the mixing temperature maintained at 40-60°C, the stirring rate at 200-400 rpm, and the mixing time at 30-90 minutes. After mixing, no chemical reaction or separation operation is performed, and the mixture is directly used in the subsequent sulfonation step.

7. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 1, characterized in that, In step S3, the sulfonating agent is liquid sulfur trioxide, which is slowly introduced into the reaction system using nitrogen gas. The molar ratio of sulfur trioxide to total alkylbenzene is 1.10:

1. The reaction temperature is controlled at 35-45°C, and the reaction time is maintained for 2 hours.

8. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 6, characterized in that, In step S5, the neutralization process uses a 15% sodium hydroxide aqueous solution, and the reaction is stirred at 50-55°C for 30-60 minutes, with the pH value controlled at 7.0±0.3, to generate a sodium heavy alkylbenzene sulfonate intermediate.

9. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 1, characterized in that, In step S6, the soluble barium salt is an aqueous solution of barium acetate with a concentration of 10-20 wt%. The metathesis reaction is carried out at 80-85°C under stirring conditions for 3 hours until the sodium ion concentration in the system is below 50 ppm, thus completing the complete replacement of barium ions.

10. The method for preparing high-performance heavy alkylbenzene sulfonate barium salt by modifying heavy alkylbenzene raw materials according to claim 1, characterized in that, In step S7, the dehydration process is carried out under vacuum at a temperature of 90-110°C and a pressure of less than or equal to 0.09 MPa. After solvent removal, the insoluble matter is removed by plate and frame filtration. The resulting filter cake is dried at 80-100°C for 4-8 hours to obtain a barium heavy alkylbenzene sulfonate product with good flowability.

Images