Pentadecyl phenol alkoxy ether sodium sulfate surfactant and preparation method thereof

Abstract

The invention relates to the technical field of surfactants, in particular to a pentadecyl phenol alkoxy ether sodium sulfate surfactant and a preparation method thereof. The invention relates to a preparation method of a pentadecyl phenol alkoxy ether sodium sulfate surfactant. The preparation method comprises the following steps: pretreating cashew nut shell liquid, and selectively hydrogenating to obtain pentadecyl phenol with specific composition; carrying out an alkoxylation reaction in the presence of a basic catalyst to obtain pentadecyl phenol polyalkoxy ether; and sulfating the pentadecyl phenol polyalkoxy ether, and neutralizing to obtain the pentadecyl phenol alkoxy ether sodium sulfate surfactant. According to the surfactant, the problem that the activity of the surfactant is reduced due to too high or too low saturation of pentadecyl phenol is solved; it is ensured that the final product has good fluidity at low temperature, production continuity is guaranteed, and oversulfation is effectively reduced; meanwhile, the production efficiency is improved, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the field of surfactant technology, specifically to a sodium pentadecylphenol alkoxy ether sulfate surfactant and its preparation method. Background Technology

[0002] Surfactants are a large class of organic compounds with a variety of excellent functions, including dispersion, wetting, penetration, emulsification, solubilization, and detergency. As the environmental performance of materials receives increasing attention, higher demands are being placed on the renewability, biodegradability, and control of harmful residues of surfactants. In recent years, renewable raw materials, represented by natural cashew nut shell extract, have gradually become a research hotspot for replacing petroleum-based raw materials.

[0003] In existing technologies, the preparation of traditional surfactants mostly uses petroleum-based compounds as raw materials. These products generally exhibit poor biodegradability due to the presence of branched groups in their molecular structure. When using cashew nut shell liquid as a raw material to prepare surfactants, two problems arise. First, existing processes struggle to separate and purify the phenolic components in the liquid, resulting in diverse phenolic structures in the raw material. This leads to increased side reactions in subsequent reactions and decreased product stability. Second, in the sulfation / sulfonation reaction stage of converting cashew nut phenol into the target surfactant, using strong reagents such as concentrated sulfuric acid or fuming sulfuric acid can easily trigger multi-site reactions leading to oversulfation, reducing the surface activity of the product, and generating large amounts of waste acid, exacerbating environmental pollution. While using aminosulfonic acid as a sulfonating agent can reduce waste acid emissions, it suffers from low sulfonation efficiency, insufficient product purity, and the potential release of ammonia nitrogen in alkaline application systems, posing a risk of eutrophication. These problems severely limit the sustainable development and application of surfactants. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a method for preparing sodium pentadecylphenol alkoxyether sulfate surfactant.

[0005] In a first aspect, this application provides a method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant, comprising the following steps: (1) Cashew shell liquid pretreatment: Decarboxylated cashew shell liquid was treated with inorganic acid solution, filtered, and centrifuged to obtain pretreated liquid; (2) Selective hydrogenation: A metal-based catalyst is added to the pretreatment solution, the temperature is raised to 80-100℃ under a nitrogen atmosphere, hydrogen is introduced, the pressure is controlled to be less than 1.2MPa, and hydrogenation is continued until the content of 3-(8,11,14-pentadecatrienyl)phenol is ≤0.5%; (3) Distillation purification: The above hydrogenation product is vacuum removed by evaporator to remove small molecule organic matter; then high-purity pentadecylphenol is obtained by vacuum distillation. (4) Alkoxylation: Add an alkaline catalyst to high-purity pentadecylphenol, and introduce 1,2-epoxyalkanes under a nitrogen atmosphere to carry out the alkoxylation reaction. After the reaction, degas under vacuum and cool down. (5) Sulphation and continuous neutralization: The product of (4) is fed into a falling film reactor, and sulfur trioxide mixed gas is introduced at the same time to carry out sulfation reaction. The sulfation product is continuously transferred to a neutralizer to adjust the pH to 8.0-11.5, and degassing is carried out again under reduced pressure and vacuum to obtain the product.

[0006] Understandably, the alkylation reaction in this application refers to the alkoxylation reaction of a compound with active hydrogen with a 1,2-epoxyalkane. The compound with active hydrogen includes alcohols, phenols, amines, and fatty acids. The 1,2-epoxyalkane includes ethylene oxide, 1,2-epoxypropane, and 1,2-epoxybutane. The reaction product, alkoxy ether, can be a copolymer of the same 1,2-epoxyalkane or a block or blend copolymer of different 1,2-epoxyalkanes, including: polyoxyethylene ether, polyoxypropylene ether, polyoxybutene ether, as well as polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene-polyoxypropylene blend copolymers, polyoxyethylene-polyoxybutene block copolymers, and polyoxyethylene-polyoxybutene blend copolymers, etc.

[0007] Cashew nut shell liquid is bio-based, abundant, and readily degradable. Pretreatment of cashew nut shell liquid yields pentadecylphenol, whose long hydrocarbon structure reduces substitution activity at the benzene ring position due to steric hindrance, thus preventing persulfation. The double bonds of 3-(8-pentadecanenyl)-phenol and 3-(8,11-pentadecanadienyl)-phenol are located at positions 8 and 11, respectively, exhibiting low activity, thus preventing persulfation and improving reaction stability during continuous production. This enhances the activity of surfactants, and the derived surfactants exhibit good low-temperature fluidity due to weak intermolecular forces from their unsaturated long chains. The double bond at position 14 of 3-(8,11,14-pentadecatrienyl)phenol is highly reactive and prone to oversulfation during sulfation. 3-pentadecaalkylphenol derivatives (such as sodium pentadecylphenol polyoxyethylene ether sulfate) easily solidify into a highly viscous paste at low temperatures, affecting the sufficient contact between the generated 3-pentadecaalkylphenol polyoxyethylene ether sulfate and the alkaline solution, resulting in poor surfactant activity. Furthermore, continuous neutralization may clog production pipelines, leading to serious accidents such as production stoppages. Therefore, this application first employs selective catalytic hydrogenation of pentadecylphenol, selecting a metal-based catalyst with preferential adsorption activity for the specific 14-position double bond of the pentadecylphenol side chain, combined with low-temperature, low-pressure hydrogenation. This approach favors hydrogenating the 14-position double bond while retaining the 8- and 11-position double bonds, thus preserving both mono- and diene components; and avoids excessive hydrogenation to generate too much saturated component such as 3-pentadecaalkylphenol. Secondly, sulfur trioxide is selected to perform a directional sulfation reaction and continuous neutralization on the pentadecylphenol alkoxy ether (a product of alkylation of high-purity pentadecylphenol with monoene and diene content greater than 80%) with the above-mentioned specific composition. This avoids the serious oversulfation caused by the use of concentrated sulfuric acid or fuming sulfuric acid in traditional sulfation, and the situation where discontinuous neutralization can easily lead to local over-alkaliness.

[0008] Therefore, this application achieves directional sulfation by selectively purifying the product through hydrogenation, allowing the sulfation reaction to occur at the hydroxyl position. This reduces byproducts and yields a product with good low-temperature fluidity, enabling continuous and thorough alkali neutralization. These two aspects synergistically enhance the activity of the generated surfactant, making it suitable for large-scale continuous production with high efficiency. This achieves the efficient preparation of surfactants from cashew nut shell liquid to pentadecylphenol alkoxyether sulfate sodium sulfate, improving upon existing technologies that suffer from persulfation, easy product solidification, poor continuous production, excessive dioxane, and non-renewable raw materials.

[0009] The metal-based catalyst mentioned in (2) includes at least one of nickel-based catalysts, rhodium-carbon catalysts, or platinum-carbon catalysts.

[0010] Preferably, the metal-based catalyst is a Raney nickel catalyst; More preferably, the metal-based catalyst is a modified Raney nickel catalyst, the preparation method of which includes: mixing ZSM-5 molecular sieve with Raney nickel powder, adding water and ball milling to form a uniform slurry, drying, calcining at 450-500℃ for 1-2 hours to obtain a composite catalyst, then adding an aqueous solution containing H2PtCl6 dropwise to it, sonicating for 15 minutes, adding ZnO powder, stirring for 30-45 minutes to make it uniformly dispersed, and calcining at 400-450℃ for 1-2 hours in a N2 atmosphere to obtain the modified Raney nickel catalyst.

[0011] More preferably, the metal-based catalyst accounts for 0.2-2.0% of the mass of the pretreatment liquid.

[0012] By employing the above-mentioned technical solution, Raney nickel catalyst is used as a metal-based catalyst for the selective hydrogenation of 3-(8,11,14-pentadecatrienyl)-phenol. The double bond at position 14 exhibits high activity; its removal through hydrogenation improves the conversion rate of directional sulfation and avoids the preferential reaction of the double bond at position 14 with sulfur trioxide during subsequent sulfation, preventing side reactions that could lead to oversulfation and consequently reduce surfactant activity. Raney nickel catalyst has a large specific surface area and numerous defect sites on its surface. These sites can serve as highly efficient active centers for hydrogen dissociation and double bond activation. The micropore size in its structure matches the spatial size of the pentadecacarbon chain side chain of cashew phenol, allowing for steric hindrance screening to adsorb the less sterically hindered double bond at position 14, further enhancing selectivity and improving conversion rate.

[0013] Further modification of the Raney nickel catalyst involves mixing ZSM-5 molecular sieve with Raney nickel. Through the initial adsorption of double bonds at the active sites of Raney nickel, the more active 14-position double bond enters the pores of the ZSM-5 molecular sieve. The confinement effect of the ZSM-5 molecular sieve increases the contact probability of the terminal double bonds. Pt doping further enhances the hydrogenation rate of the terminal double bonds, ensuring catalyst activity. Meanwhile, the electronic effect of the ZnO promoter allows oxygen vacancies to transfer electrons to Ni, lowering the Ni's central energy and weakening the adsorption of the 8- and 11-position double bonds in the chain, achieving selective hydrogenation. This provides a highly efficient and stable catalyst for the selective hydrogenation step, improving the efficiency and product quality of selective hydrogenation. It also helps ensure the directionality of the subsequent sulfation reaction, improving the performance and quality of the final product, sodium pentadecylphenol alkoxyether sulfate. The pretreatment liquid and metal-based catalyst disclosed in this application, in a specific mass ratio, enable the selective hydrogenation reaction to proceed smoothly, effectively control the range of the content of each component of 3-pentadecanylphenol, ensure that the final product has good fluidity at low temperatures, guarantee the continuity of production, and at the same time improve production efficiency and reduce costs. If the pretreatment liquid is too small and the catalyst is too large, the content of 3-pentadecanylphenol may increase, causing the final product, pentadecylphenol alkoxy ether sodium sulfate, to easily solidify at low temperatures, affecting the continuity and sufficiency of alkali neutralization, clogging the production pipeline, and also increasing production costs.

[0014] The conditions for vacuum distillation in (3) are a temperature of 180-190℃ and an absolute vacuum of 4-10Pa.

[0015] The alkaline catalyst in (4) includes one or more of alkali metal hydroxides, carbonates, and C1-C4 alkoxides.

[0016] The vacuum degassing conditions in (4) are: degassing for 45-60 minutes at a vacuum of -0.096 to -0.099 MPa.

[0017] The sulfur trioxide mixture in (5) is a mixture of sulfur trioxide with a volume concentration of 3-8% diluted with dry air, and the dew point of the dry air is below -40°C.

[0018] Preferably, the molar ratio of the product of (4) in (5) to sulfur trioxide is 1:(1.03-1.2).

[0019] By adopting the above technical solution, sulfur trioxide is introduced as a mixed gas, which can avoid excessively high sulfur trioxide concentration leading to an overly vigorous reaction, which may result in the side reaction of persulfation of benzene ring and side chain, reducing the activity of surfactant. In step (4), the product and sulfur trioxide within the ratio range of this application can increase the sulfonation degree of the surfactant containing pentadecylphenol alkoxy ether sodium sulfate, reduce the occurrence of side reactions, and improve the activity performance of surfactant. Too little sulfur trioxide will lead to incomplete sulfation reaction, resulting in an increase in unreacted alkoxy ethers in the product, a decrease in the effective components of surfactant, affecting the activity and performance of surfactant, and reducing functions such as dispersion and detergency; too much sulfur trioxide is prone to triggering multi-site reactions leading to persulfation, which reduces the surface activity of product and may also generate more by-products, affecting product quality.

[0020] In some embodiments, in the sulfation and continuous neutralization step (5), C8-C14 fatty alcohol polyoxyethylene ether or fatty alcohol alkoxy ether is mixed with the product of (4) and then introduced into a falling film reactor; the mass ratio of the product of (4) to C8-C14 fatty alcohol polyoxyethylene ether or fatty alcohol alkoxy ether is 1:(0.5-2.0).

[0021] Preferably, the C8-C14 fatty alcohol polyoxyethylene ether comprises one or more of the following: n-octyl alcohol polyoxyethylene ether, isooctyl alcohol polyoxyethylene ether, n-decanol polyoxyethylene ether, isodecanol polyoxyethylene ether, dodecyl / tetradecyl alcohol polyoxyethylene ether, isodecyl alcohol polyoxyethylene ether, and isotridecyl alcohol polyoxyethylene ether; the fatty alcohol alkoxy ether comprises one or more of the following: n-octyl alcohol alkoxy ether, isooctyl alcohol alkoxy ether, n-decanol alkoxy ether, isodecyl alcohol alkoxy ether, dodecyl / tetradecyl alcohol alkoxy ether, isodecyl alcohol alkoxy ether, and isotridecyl alcohol alkoxy ether.

[0022] More preferably, the mass ratio of the product of (4), fatty alcohol polyoxyethylene ether or fatty alcohol alkoxy ether is 1:(1.5-1.8).

[0023] The surfactants obtained using the above-mentioned technical solutions exhibit better surface activity. This may be due to two main reasons: First, compared to a single pentadecylbenzene long chain, the linear hydrophobic long chain of fatty alcohols can reduce intermolecular forces, improve the fluidity of the mixture, and facilitate continuous neutralization to obtain fully alkali-neutralized products, thereby enhancing the surfactant activity. Second, the combination of multiple long-chain hydrophobic groups of different chain lengths allows for better arrangement of the hydrophobic segments, resulting in denser micelles that effectively reduce surface tension. The C8-C14 chain length ensures hydrophobicity while also facilitating the rational arrangement of the aforementioned hydrophobic chains.

[0024] Secondly, a sodium pentadecylphenol alkoxyether sulfate surfactant is provided, which is prepared according to the above-mentioned preparation method of sodium pentadecylphenol alkoxyether sulfate surfactant.

[0025] It is understandable that the surfactant obtained by the preparation method of the first aspect possesses all the beneficial effects imparted to the surfactant by the preparation method of the first aspect.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. This application achieves efficient preparation of a surfactant, pentadecylphenol alkoxyl ether sodium sulfate, from cashew nut shell liquid by selective catalytic hydrogenation, followed by alkoxylation of the unsaturated pentadecylphenol, and finally directional sulfation of the alkoxy ether and sulfur trioxide. This solves the problems of persulfation, easy coagulation of the product, excessive dioxane, and non-renewable raw materials in existing technologies. The polyalkoxyl ether chain constitutes the hydrophilic part of the surfactant, which, together with the hydrophobic pentadecyl group, gives the surfactant excellent dispersing, emulsifying, solubilizing, and detergency properties.

[0027] 2. This application uses Raney nickel catalyst for the selective hydrogenation of 3-(8,11,14-pentadectrienyl)-phenol. The micropore size in its structure matches the spatial size of the pentadectomy ...

[0028] 3. This application obtains a surfactant with better activity by sulfation of a mixture of pentadecylphenol polyalkoxy ether and fatty alcohol polyoxyethylene ether or fatty alcohol alkoxy ether through a specific preparation method and continuous neutralization. Attached Figure Description

[0029] Figure 1The image shows the ¹H NMR spectrum of the sodium pentadecanylphenol polyoxyethylene (8) ether sulfate compound prepared in Example 1.

[0030] Figure 2 yes Figure 1 A magnified view of a portion of the image.

[0031] Figure 3 These are MS diagrams of the positive ion mode and negative ion mode of the pentadecylphenol polyoxyethylene (4) ether sodium sulfate prepared in Example 2. Detailed Implementation

[0032] In this application, the sulfuric acid solution was purchased from Aladdin; the ZSM-5 molecular sieve was purchased from Shandong Qilu Huaxin High-Tech Co., Ltd.; the Raney nickel catalyst was purchased from Dalian Zhenhao Catalyst Technology Co., Ltd.; 1,2-ethylene oxide was purchased from Jiangsu Aoke Chemical Co., Ltd.; the decarboxylated cashew nut shell liquid came from Naisu (Mozambique) sole proprietorship; and other raw materials were all available commercially.

[0033] Preparation Example 1 Preparation of modified Raney nickel catalyst: 25g ZSM-5 molecular sieve and 10g Raney nickel powder were mixed, 10ml water was added and ball milled for 1h to form a uniform slurry. After drying at 100℃ for 6h, the slurry was calcined at 450℃ for 2h to obtain a composite catalyst. Then, 15ml aqueous solution containing 0.5g H2PtCl6 was added dropwise to the composite catalyst, and the mixture was sonicated for 15min. 2g ZnO powder was added and stirred for 30min to disperse the catalyst evenly. The catalyst was then calcined at 400℃ for 1h under N2 atmosphere to obtain the modified Raney nickel catalyst. Example 1

[0034] A method for preparing a sodium sulfate surfactant containing pentadecylphenol alkoxyether: 150 kg of decarboxylated cashew shell liquid is added to a reactor, followed by 300 g of 50% sulfuric acid solution. The mixture is stirred and heated to 80°C, then stirred continuously for 30 min. The solution is filtered through a series of 200-mesh and 500-mesh stainless steel filters, and then centrifuged at high speed using a disc centrifuge. The resulting pretreated liquid is transferred to a hydrogenation unit, where 1% (by weight) of Raney nickel catalyst is added. The air inside the unit is replaced with nitrogen to reduce the oxygen content to <100 ppm. The temperature is raised to 85°C, and hydrogen is continuously introduced while maintaining the pressure inside the unit below 1.2 MPa. After introducing 780 g of hydrogen, the process is stopped. Hydrogen gas was introduced, and when the pressure inside the apparatus was ≤0.2MPa, stirring was stopped, and nitrogen gas was introduced to purge for 30 minutes. The catalyst was removed by filtration, and the content of the hydrogenation product 3-(8,11,14-pentadecatrienyl)-phenol was determined by HPLC to be 0.2%. The hydrogenation product was preheated to 170℃, and small molecule organic matter was first removed by passing it through a thin-film evaporator with a vacuum degree of 100Pa. Then it was heated to 180℃ and passed through a short-path evaporator with a vacuum degree of 4Pa to obtain the distillation product pentadecylphenol. Take 60.2 kg of distilled product and put it into an alkoxylation reactor. Then add 260 g of 40% potassium hydroxide solution, heat to 110°C, vacuum dehydrate for 40 min, vacuum degree -0.099 MPa, and take a sample to test the water content equal to 0.05%. After dehydration, replace the oxygen content in the reactor with nitrogen until the oxygen content is <100 ppm, heat to 130°C, and continuously introduce 70.4 kg of ethylene oxide. During this period, control the reaction temperature at 130°C. After all the ethylene oxide has been introduced, maintain the material temperature and continue the reaction for 60 min. Then vacuum degas for 60 min, vacuum degree -0.099 MPa, and take a sample to test the dioxane content. The dioxane content is less than 10 ppm. After vacuuming is completed, add acetic acid to adjust the pH to 7 to obtain pentadecylphenol polyoxyethylene (8) ether. 132 kg of pentadecylphenol polyoxyethylene (8) ether was introduced into a falling film reactor, and a mixed gas of sulfur trioxide with a volume concentration of 5% diluted with dry air was introduced simultaneously. The dew point of the dry air was -40℃, so that the molar ratio of pentadecylphenol polyoxyethylene (8) ether to sulfur trioxide was 1:1.1. After the sulfation reaction, the degree of sulfation was measured by sampling. The sulfation product was continuously transferred to a neutralizer, and 2.5% sodium hydroxide solution was continuously introduced for neutralization to control the pH value at 10.5. The product was then continuously introduced into a stripping tower, and vacuum was applied at 50℃. After the dioxane content was lower than 10 ppm, an appropriate amount of deionized water was added to adjust the product solid content to 75%, thus obtaining pentadecylphenol alkoxy ether sodium sulfate surfactant. Example 2

[0035] A method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant: 150 kg of decarboxylated cashew shell liquid is added to a reaction vessel, followed by 300 g of... A 50% sulfuric acid solution was stirred and heated to 80°C, then stirred for 30 minutes. The solution was filtered through a series of 200-mesh and 500-mesh stainless steel filters, followed by a disc centrifugal filter. The resulting pretreated solution was transferred to a hydrogenation unit. 1% (by weight) of Raney nickel catalyst was added. The air inside the unit was replaced with nitrogen to ensure an oxygen content <100 ppm. The temperature was raised to 85°C, and hydrogen was continuously introduced while maintaining the pressure inside the unit below 1.2 MPa. After introducing 780 g of hydrogen, the hydrogen supply was stopped. Once the pressure inside the unit was ≤0.2 MPa, stirring was stopped, and nitrogen was introduced to purge for 30 minutes. The catalyst was removed by filtration. HPLC analysis showed that the hydrogenation product 3-(8,11,14-pentadecatrienyl)-phenol contained 0.2%. The hydrogenated product was then heated to 170°C, first passing through a 100 Pa vacuum thin-film evaporator to remove small molecule organic matter, then heated to 180°C and passed through a short-path evaporator with a 4 Pa ​​vacuum to obtain the distilled product pentadecylphenol. Take 60.2 kg of distilled product and put it into an alkoxylation reactor. Then add 260 g of 40% potassium hydroxide solution, heat to 110°C, vacuum dehydrate for 40 min, vacuum degree -0.099 MPa, and take a sample to test the water content equal to 0.05%. After dehydration, replace the oxygen content in the reactor with nitrogen until the oxygen content is <100 ppm, heat to 130°C, and continuously introduce 35.2 kg of ethylene oxide. During this period, control the reaction temperature at 130°C. After all the ethylene oxide has been introduced, maintain the material temperature and continue the reaction for 60 min. Then vacuum degas for 60 min, vacuum degree -0.099 MPa, and take a sample to test the dioxane content. The dioxane content is less than 10 ppm. After vacuuming is completed, add acetic acid to adjust the pH to 7 to obtain pentadecylphenol polyoxyethylene (4) ether. 47.7 kg of pentadecylphenol polyoxyethylene (4) ether and 84.3 kg of dodecyl / tetradecyl alcohol polyoxyethylene (2) ether were mixed and fed into a falling film reactor. Simultaneously, a mixed gas of sulfur trioxide diluted with dry air at a volume concentration of 5% (dew point -40°C) was introduced, ensuring a molar ratio of 1:1.1 between the pentadecylphenol polyoxyethylene (4) ether and dodecyl / tetradecyl alcohol polyoxyethylene (2) ether mixture and sulfur trioxide. After sulfation, samples were taken to measure the degree of sulfation. The sulfation product was then continuously transferred to a neutralizer, where a 2.5% sodium hydroxide solution was continuously introduced for neutralization, controlling the pH at 10.5. The product was then continuously fed into a stripping tower, where a vacuum was applied at 50°C. Once the dioxane content was below 10 ppm, an appropriate amount of deionized water was added to adjust the product solid content to 75%, yielding a pentadecylphenol alkoxy ether sodium sulfate surfactant. (Reference) Figure 3 The corresponding positive ion mode mass spectrum and negative ion mode mass spectrum of sodium pentadecyl phenol polyoxyethylene (4) ether sulfate. Example 3

[0036] A method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant: 150 kg of decarboxylated cashew shell liquid is added to a reaction vessel, followed by 300 g of... A 50% sulfuric acid solution was stirred and heated to 80°C, then stirred for 30 minutes. The solution was filtered through a series of 200-mesh and 500-mesh stainless steel filters, followed by a disc centrifugal filter. The resulting pretreated solution was transferred to a hydrogenation unit. 1% (by weight) of Raney nickel catalyst was added. The air inside the unit was replaced with nitrogen to ensure an oxygen content <100 ppm. The temperature was raised to 85°C, and hydrogen was continuously introduced while maintaining the pressure inside the unit below 1.2 MPa. After introducing 780 g of hydrogen, the hydrogen supply was stopped. Once the pressure inside the unit was ≤0.2 MPa, stirring was stopped, and nitrogen was introduced to purge for 30 minutes. The catalyst was removed by filtration. HPLC analysis showed that the hydrogenation product 3-(8,11,14-pentadecatrienyl)-phenol contained 0.2%. The hydrogenated product was then heated to 170°C, first passing through a 100 Pa vacuum thin-film evaporator to remove small molecule organic matter, then heated to 180°C and passed through a short-path evaporator with a 4 Pa ​​vacuum to obtain the distilled product pentadecylphenol. Take 60.2 kg of distilled product and put it into an alkoxylation reactor. Then add 260 g of 40% potassium hydroxide solution, heat to 110°C, vacuum dehydrate for 40 min, vacuum degree -0.099 MPa, and take a sample to test the water content equal to 0.05%. After dehydration, replace the oxygen content in the reactor with nitrogen until the oxygen content is <100 ppm, heat to 130°C, and continuously introduce 52.8 kg of ethylene oxide. During this period, control the reaction temperature at 130°C. After all the ethylene oxide has been introduced, maintain the material temperature and continue the reaction for 60 min. Then vacuum degas for 60 min, vacuum degree -0.099 MPa, take a sample to test the dioxane content. The dioxane content is less than 10 ppm. After vacuuming is completed, add acetic acid to adjust the pH to 7 to obtain pentadecylphenol polyoxyethylene (6) ether. 56.5 kg of pentadecylphenol polyoxyethylene (6) ether and 45.0 kg of isodecanol polyoxypropylene (2) polyoxyethylene (4) ether were mixed and fed into a falling film reactor. At the same time, a mixed gas of sulfur trioxide with a volume concentration of 5% diluted with dry air was introduced. The dew point of the dry air was -40℃, so that the molar ratio of pentadecylphenol polyoxyethylene (6) ether and isodecanol polyoxypropylene (2) polyoxyethylene (4) ether to sulfur trioxide was 1:1.1. After the sulfation reaction, the degree of sulfation was measured by sampling. The sulfation product was then continuously transferred to a neutralizer and neutralized by continuously feeding 2.5% sodium hydroxide solution to control the pH value at 10.5. The product was then continuously fed into a stripping tower and vacuumed at 50℃. After the dioxane content was lower than 10 ppm, an appropriate amount of deionized water was added to adjust the product solid content to 75%, thus obtaining pentadecylphenol alkoxy ether sodium sulfate surfactant. Example 4

[0037] A method for preparing a sodium sulfate surfactant containing pentadecylphenol alkoxyether: 150 kg of decarboxylated cashew shell liquid is added to a reactor, followed by 300 g of 50% sulfuric acid solution. The mixture is stirred and heated to 80°C, then stirred continuously for 30 min. The solution is filtered through a series of 200-mesh and 500-mesh stainless steel filters, and then centrifuged at high speed using a disc centrifuge. The resulting pretreated liquid is transferred to a hydrogenation unit, where 1% (by weight) of Raney nickel catalyst is added. The air inside the unit is replaced with nitrogen to reduce the oxygen content to <100 ppm. The temperature is raised to 85°C, and hydrogen is continuously introduced while maintaining the pressure inside the unit below 1.2 MPa. After introducing 780 g of hydrogen, the process is stopped. Hydrogen gas was introduced, and when the pressure inside the apparatus was ≤0.2MPa, stirring was stopped, and nitrogen gas was introduced to purge for 30 minutes. The catalyst was removed by filtration, and the content of the hydrogenation product 3-(8,11,14-pentadecatrienyl)-phenol was determined by HPLC to be 0.2%. The hydrogenation product was preheated to 170℃, and small molecule organic matter was first removed by passing it through a thin-film evaporator with a vacuum degree of 100Pa. Then it was heated to 180℃ and passed through a short-path evaporator with a vacuum degree of 4Pa to obtain the distillation product pentadecylphenol. 60.2 kg of distilled product was added to an alkoxylation reactor, followed by 280 g of a 40% potassium hydroxide solution. The mixture was heated to 110°C and dehydrated under vacuum for 40 minutes at a vacuum degree of -0.099 MPa. A sample was taken to test the water content, which was found to be 0.05%. After dehydration, nitrogen was used to purge the reactor until the oxygen content was <100 ppm. The temperature was then raised to 120°C, and 69.6 kg of propylene oxide was continuously introduced while maintaining the reaction temperature at 130°C. The reaction proceeded after all the propylene oxide had been introduced. Maintain the material temperature and continue the reaction for 180 min. Then, continuously introduce 8.8 kg of ethylene oxide while controlling the reaction temperature at 130 °C. After all the ethylene oxide has been introduced, maintain the material temperature at 130 °C and continue the reaction for 60 min. Then, degas under vacuum for 60 min with a vacuum degree of -0.099 MPa. Take a sample to test for dioxane. The dioxane content is less than 10 ppm. After the vacuuming is completed, add acetic acid to adjust the pH to 7 to obtain pentadecylphenol polyoxypropylene (6) polyoxyethylene (2) ether. 73.7 kg of pentadecylphenol polyoxypropylene (6) polyoxyethylene (2) ether was introduced into a falling film reactor. At the same time, a mixed gas of sulfur trioxide with a volume concentration of 5% diluted with dry air was introduced. The dew point of the dry air was -40℃, so that the molar ratio of pentadecylphenol polyoxypropylene (6) polyoxyethylene (2) ether to sulfur trioxide was 1:1.1. After the sulfation reaction, the degree of sulfation was measured by sampling. The sulfation product was continuously transferred to a neutralizer, and 2.5% sodium hydroxide solution was continuously introduced for neutralization. The pH value was controlled at 10.5. The product was then continuously introduced into a stripping tower, and vacuum was applied at 50℃. After the dioxane content was lower than 10 ppm, an appropriate amount of deionized water was added to adjust the product solid content to 75%, thus obtaining pentadecylphenol alkoxy ether sodium sulfate surfactant. Example 5

[0038] A method for preparing a sodium sulfate surfactant containing pentadecylphenol alkoxyether: 150 kg of decarboxylated cashew shell liquid is added to a reactor, followed by 300 g of 50% sulfuric acid solution. The mixture is stirred and heated to 80°C, then stirred continuously for 30 min. The solution is filtered through a series of 200-mesh and 500-mesh stainless steel filters, and then centrifuged at high speed using a disc centrifuge. The resulting pretreated liquid is transferred to a hydrogenation unit, where 1% (by weight) of Raney nickel catalyst is added. The air inside the unit is replaced with nitrogen to reduce the oxygen content to <100 ppm. The temperature is raised to 85°C, and hydrogen is continuously introduced while maintaining the pressure inside the unit below 1.2 MPa. After introducing 780 g of hydrogen, the process is stopped. Hydrogen gas was introduced, and when the pressure inside the apparatus was ≤0.2MPa, stirring was stopped, and nitrogen gas was introduced to purge for 30 minutes. The catalyst was removed by filtration, and the content of the hydrogenation product 3-(8,11,14-pentadecatrienyl)-phenol was determined by HPLC to be 0.2%. The hydrogenation product was preheated to 170℃, and small molecule organic matter was first removed by passing it through a thin-film evaporator with a vacuum degree of 100Pa. Then it was heated to 180℃ and passed through a short-path evaporator with a vacuum degree of 4Pa to obtain the distillation product pentadecylphenol. Take 60.2 kg of distilled product and put it into an alkoxylation reactor. Then add 559 g of 30% potassium methoxide methanol solution. Heat to 90°C and dehydrate under vacuum for 60 min with a vacuum degree of -0.099 MPa. Take a sample and test the water content to be equal to 0.05%. After dehydration, replace the oxygen content in the reactor with nitrogen until the oxygen content is <100 ppm. Heat to 120°C and continuously introduce 104.4 kg of propylene oxide. During this period, control the reaction temperature at 130°C. After all the propylene oxide has been introduced, maintain the material temperature and continue the reaction for 180 min. Cool down to 100°C and degas under vacuum for 60 min with a vacuum degree of -0.099 MPa. After vacuuming is completed, add acetic acid to adjust the pH to 7 to obtain pentadecylphenol polyoxypropylene (9) ether. 82.3 kg of pentadecylphenol polyoxypropylene (9) ether was introduced into a falling film reactor, and a mixed gas of sulfur trioxide with a volume concentration of 5% diluted with dry air was introduced at the same time. The dew point of the dry air was -40℃, so that the molar ratio of pentadecylphenol polyoxypropylene (9) ether to sulfur trioxide was 1:1.15. After the sulfation reaction, the degree of sulfation was measured by sampling. The sulfation product was continuously transferred to a neutralizer, and 2.5% sodium hydroxide solution was continuously introduced for neutralization. The pH value was controlled at 10.5. Then, an appropriate amount of deionized water was added to adjust the solid content of the product to 75%, and the pentadecylphenol alkoxy ether sodium sulfate surfactant was obtained. Example 6

[0039] The only difference between this embodiment and Example 1 is that the Raney nickel catalyst used accounts for 4% of the mass of the pretreatment liquid. Example 7

[0040] The only difference between this embodiment and Example 1 is that the Raney nickel catalyst is the modified Raney nickel catalyst prepared in Example 1. Example 8

[0041] The only difference between this embodiment and Embodiment 2 is that 60 kg of pentadecylphenol polyoxyethylene (4) ether and 72 kg of dodecadecyl / tetradecyl alcohol polyoxyethylene (2) ether are mixed and then fed into a falling film reactor. Example 9

[0042] The only difference between this embodiment and Embodiment 2 is that 42 kg of pentadecylphenol polyoxyethylene (4) ether and 90 kg of dodecadecyl / tetradecyl alcohol polyoxyethylene (2) ether are mixed and then fed into a falling film reactor.

[0043] Comparative Example 1 The only difference between this embodiment and Example 1 is that the hydrogenated product was not purified by distillation and was directly added to the alkoxylation reactor.

[0044] The sodium pentadecylphenol alkoxyether sulfate surfactants prepared in the examples and comparative examples were subjected to the following tests: Testing of active ingredient content: Refer to GB / T-5173-2018; Total solids content test: 120℃, dried for 2 hours; Conversion rate: active ingredient content / total solids content; Surface tension: Dataphysics DCAT 21 surface tension meter; results are shown in Table 1; In Examples 1 and 6-7, the hydrogenation purity of 3-(8-pentadecanenyl)-phenol and 3-(8,11-pentadecanadienyl)-phenol in the distillation products was determined by HPLC; the results are shown in Table 2. Table 1

[0045] Table 2

[0046] As shown in the table above, the surfactants prepared in the above embodiments of this application have stable appearance properties, high solid content, high conversion rate, and high efficiency in reducing surface tension. They can prevent the product, pentadecylphenol alkoxy ether sodium sulfate, from solidifying at low temperatures, thus preventing blockage of production pipelines and accidents. Furthermore, they overcome the shortcomings of poor biodegradability of existing surfactants and meet environmental protection requirements. As shown in Examples 1, 2, and 8-9, compared to the long chain of pentadecylbenzene, the straight-chain hydrophobic long chain of fatty alcohol can reduce intermolecular forces, improve the fluidity of the mixture, and facilitate continuous neutralization to obtain fully alkali-neutralized products, thereby improving the activity of the surfactant. In this application, under the preferred ratio range, the combination of multiple different hydrophobic groups with similar chain lengths results in a better arrangement of hydrophobic segments, which is beneficial for reducing surface tension. The C8-C14 chain length ensures hydrophobicity while also facilitating the rational arrangement of the hydrophobic chains. Comparing Examples 1 and 6-7, it can be seen that by modifying the Raney nickel catalyst with molecular sieves, the double bond at position 14 can enter the ZSM-5 molecular sieve channels to achieve highly selective hydrogenation, increase the concentration of the target product, and enable the final product to have good fluidity at low temperatures, thus ensuring the continuity of production.

[0047] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant, characterized in that: Includes the following steps: (1) Cashew shell liquid pretreatment: Decarboxylated cashew shell liquid was treated with inorganic acid solution, filtered, and centrifuged to obtain pretreated liquid; (2) Selective hydrogenation: A metal-based catalyst is added to the pretreatment solution, the temperature is raised to 80-100℃ under a nitrogen atmosphere, hydrogen is introduced, the pressure is controlled to be less than 1.2MPa, and hydrogenation is continued until the content of 3-(8,11,14-pentadecatrienyl)phenol is ≤0.5%; (3) Distillation purification: The above hydrogenation product is vacuum removed by evaporator to remove small molecule organic matter; then high-purity pentadecylphenol is obtained by vacuum distillation. (4) Alkoxylation: Add an alkaline catalyst to high-purity pentadecylphenol, and introduce 1,2-epoxyalkanes under a nitrogen atmosphere to carry out the alkoxylation reaction. After the reaction, degas under vacuum and cool down. (5) Sulphation and continuous neutralization: The product of (4) is fed into a falling film reactor, and sulfur trioxide mixed gas is introduced at the same time to carry out sulfation reaction. The sulfation product is continuously transferred to a neutralizer to adjust the pH to 8.0-11.5, and degassing is carried out again under reduced pressure and vacuum to obtain the product.

2. The method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant according to claim 1, characterized in that: The metal-based catalyst mentioned in (2) includes at least one of nickel-based catalysts, rhodium-carbon catalysts, or platinum-carbon catalysts.

3. The method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant according to claim 2, characterized in that: The metal-based catalyst accounts for 0.2-2.0% of the mass of the pretreatment liquid.

4. The method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant according to claim 1, characterized in that: The vacuum distillation conditions in (3) are a temperature of 180-190℃ and an absolute vacuum of 4-10Pa.

5. The method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant according to claim 1, characterized in that: The vacuum degassing conditions in (4) are: degassing for 45-60 minutes at a vacuum of -0.096 to -0.099 MPa.

6. The method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant according to claim 1, characterized in that: The sulfur trioxide mixture in (5) is a mixture of sulfur trioxide with a volume concentration of 3-8% diluted with dry air.

7. The method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant according to claim 1, characterized in that: The molar ratio of the product of (4) in (5) to sulfur trioxide is 1:(1.03-1.2).

8. The method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant according to claim 1, characterized in that: In the sulfation and continuous neutralization step (5), C8-C14 fatty alcohol polyoxyethylene ether or fatty alcohol alkoxy ether is mixed with the product of (4) and then introduced into a falling film reactor; the mass ratio of the product of (4) to C8-C14 fatty alcohol polyoxyethylene ether or fatty alcohol alkoxy ether is 1: (0.5-2.0).

9. The method for preparing a sodium pentadecylphenol alkoxyether sulfate surfactant according to claim 8, characterized in that: The C8-C14 fatty alcohol polyoxyethylene ethers include one or more of the following: n-octyl alcohol polyoxyethylene ether, isooctyl alcohol polyoxyethylene ether, n-decanol polyoxyethylene ether, isodecanol polyoxyethylene ether, dodecyl / tetradecyl alcohol polyoxyethylene ether, iso-dodecyl alcohol polyoxyethylene ether, and iso-trigetyl alcohol polyoxyethylene ether; the fatty alcohol alkoxy ethers include one or more of the following: n-octyl alcohol alkoxy ether, isooctyl alcohol alkoxy ether, n-decanol alkoxy ether, isodecanol alkoxy ether, dodecyl / tetradecyl alcohol alkoxy ether, iso-dodecyl alcohol alkoxy ether, and iso-trigetyl alcohol alkoxy ether.

10. The sodium pentadecylphenol alkoxyether sulfate surfactant prepared by the method of any one of claims 1-9.

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