A process for the synthesis of sorbitan monooleate

Abstract

The application discloses a synthesis process of sorbitan monooleate, and belongs to the technical field of non-ionic surfactant preparation. The process comprises the following steps: mixing sorbitol with an etherification catalyst, and performing a first-stage dehydration reaction to obtain product A; adding oleic acid and a catalyst a into the product A, performing a second-stage esterification reaction, and cooling to obtain product B; adding a passivation agent into the product B, stirring, filtering, and obtaining a crude product; and performing decoloring and deodorizing treatment on the crude product to obtain the sorbitan monooleate; wherein the catalyst a is prepared by introducing a titanium source into SBA-15, modifying the SBA-15 by amino functionalization, and loading phosphotungstic acid in three steps. The application adopts the amino-modified titanium-silicon mesoporous molecular sieve loaded with phosphotungstic acid as the catalyst, has the advantages of less by-products, light color of the product, recyclable catalyst and the like, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals, specifically relating to a synthesis process of sorbitan monooleate. Background Technology

[0002] Sorbitan monooleate (Span-80), chemically named dehydrated sorbitan monooleate, has the molecular formula C80. 24 H 44 O6, CAS number 1338-43-8, is a typical polyol-type nonionic surfactant with excellent emulsifying, dispersing, foaming and wetting properties. With an HLB value of 4.3, it belongs to the water-in-oil emulsion type and is widely used in food, medicine, cosmetics, emulsion explosives, textiles, oil fields and other fields.

[0003] The synthesis of Span 80 involves both internal etherification (dehydration and cyclization of sorbitol) and esterification (reaction of dehydrated sorbitol with oleic acid to form an ester). Currently, the main synthetic methods for Span 80 include one-step and two-step methods. The one-step method involves directly etherifying and esterifying sorbitol and oleic acid at 190-240°C in the presence of a catalyst. For example, Chinese invention patent application CN102260228A discloses a one-step process for synthesizing sorbitan oleate. Sorbitol with a water content of 30% is dehydrated under vacuum, and then oleic acid and a high-efficiency composite catalyst are directly added at 80°C to carry out etherification and esterification reactions. The temperature is controlled at 190-240°C, the vacuum degree is controlled above 0.098 MPa, and the reaction time is 5-8 hours. Although this method is convenient to operate, the high reaction temperature easily leads to the formation of internal ethers and polymers, resulting in products with poor regularity, dark color, and unstable quality. Therefore, it can only be used in industries such as petroleum, mining, and textiles.

[0004] The two-step method includes two routes: esterification followed by etherification and etherification followed by esterification. The esterification-then-etherification route involves first esterifying sorbitol and oleic acid in the presence of an alkaline catalyst. When the acid value drops below 10, an acidic catalyst is then added to form an anhydride. This method improves the color of the product compared to the one-step method, but still results in more impurities.

[0005] The etherification-then-esterification route involves dehydrating sorbitol to anhydride in the presence of an acidic catalyst, followed by esterification with oleic acid. For example, Chinese invention patent application CN102910994A discloses a method for synthesizing an emulsifier SP-80 for emulsion explosives. Sorbitol and a catalyst are etherified under vacuum at 100-150°C for 50-90 minutes to generate dehydrated sorbitol anhydride. The dehydrated sorbitol anhydride, oleic acid, and a basic catalyst are then mixed uniformly and esterified at 170-220°C for 2-5 hours. This method has relatively mild reaction conditions, but the process is lengthy, and different catalysts are required for the etherification and esterification stages, necessitating catalyst separation or replacement midway, making the operation cumbersome.

[0006] In existing technologies, the catalysts used in the synthesis of Span 80 mainly include zinc oxide, sodium hydroxide, potassium hydroxide, and phosphoric acid. Studies have shown that using zinc oxide as a catalyst, under vacuum conditions at 210℃ for 2.5 h, the product's acid value, saponification value, and hydroxyl value are 5.8, 154.1, and 207.3 mg KOH / g, respectively. Other studies have investigated the effects of phosphoric acid, phosphorous acid, and p-toluenesulfonic acid as dehydration catalysts on the dehydration of sorbitol. These traditional catalysts have shortcomings in catalytic activity and selectivity, leading to problems such as numerous byproducts, dark product color, and difficulty in catalyst recovery.

[0007] Therefore, developing a Span 80 synthesis process with fewer byproducts, lighter product color, and recyclable catalyst has significant industrial application value. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a process for synthesizing sorbitan monooleate.

[0009] Terminology Explanation: Unless otherwise defined, all technical terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this subject matter pertains. Unless otherwise stated, all patents, patent inventions, and disclosures cited throughout this document are incorporated herein by reference in their entirety. Where multiple definitions exist for terms herein, the definitions provided in this chapter shall prevail.

[0010] It should be understood that the above brief description and the following detailed description are exemplary and for illustrative purposes only, and do not limit the subject matter of the invention in any way. In this invention, the singular is used in conjunction with the plural unless otherwise specifically stated. It should also be noted that, unless otherwise stated, the use of “or” or “or” means “and / or”. Furthermore, the use of the term “comprising” and other forms such as “including,” “containing,” and “contains” are not limiting.

[0011] Unless otherwise stated, conventional methods within the scope of the art shall be used.

[0012] Unless specifically defined herein, the use of all commercially available products herein employs standard techniques. For example, it may be carried out using the manufacturer's instructions for use with the kit, or in accordance with methods known in the art or the description of this invention. The techniques and methods described herein can generally be implemented according to conventional methods well known in the art, based on the descriptions in the various summary and more specific documents cited and discussed in this specification.

[0013] The terms “optional / arbitrary” or “optionally / arbitrarily” mean that the event or situation described below may or may not occur, including both the occurrence and non-occurrence of the event or situation.

[0014] In a first aspect, the present invention provides a process for synthesizing sorbitan monooleate, comprising the following steps: (1) Sorbitol was mixed with an etherification catalyst and subjected to a first-stage dehydration reaction to obtain product A; (2) Add oleic acid and catalyst a to product A to carry out the second stage of esterification reaction, cool down, and obtain product B; (3) Add passivating agent to product B, stir, filter, and obtain crude product; (4) The crude product was decolorized and deodorized to obtain sorbitan monooleate; The preparation method of catalyst a includes the following steps: S1. Add the titanium source to the aqueous dispersion of SBA-15 molecular sieve, perform hydrothermal reaction, filter, wash, dry, and calcine to obtain Ti-SBA-15; S2. Disperse Ti-SBA-15 in anhydrous toluene, add 3-aminopropyltriethoxysilane to react, filter, wash, and dry to obtain NH2-Ti-SBA-15; S3. Impregnate NH2-Ti-SBA-15 in an aqueous solution of phosphotungstic acid, filter, wash, and dry to obtain catalyst a.

[0015] Preferably, the etherification catalyst in step (1) is selected from at least one of phosphoric acid, p-toluenesulfonic acid, phosphorous acid and sulfuric acid, the amount of the etherification catalyst is 0.2%-3.0% of the mass of sorbitol, the temperature of the first stage dehydration reaction is 120-140℃, and the reaction time is 1-3h.

[0016] Preferably, the molar ratio of oleic acid to sorbitol in step (2) is 1-1.8:1, and the amount of catalyst a is 1%-5% of the total mass of sorbitol and oleic acid.

[0017] Preferably, the conditions for the second stage esterification reaction in step (2) include: a temperature of 160-200℃, a vacuum degree of -0.08~-0.1MPa, and a reaction time of 3-5h; the cooling temperature is 80-90℃.

[0018] More preferably, the titanium source in step S1 is tetrabutyl titanate or titanium tetrachloride, and the mass ratio of the titanium source to the SBA-15 molecular sieve is 1:5-20.

[0019] More preferably, the hydrothermal reaction temperature in step S1 is 95-105℃, the reaction time is 12-24h, the calcination temperature is 400-600℃, and the calcination time is 2-6h.

[0020] More preferably, in step S2, the mass ratio of 3-aminopropyltriethoxysilane to Ti-SBA-15 is 0.2-0.5:1, the reaction temperature is 80-120℃, and the reaction time is 6-24h.

[0021] More preferably, in step S3, the mass ratio of phosphotungstic acid to NH2-Ti-SBA-15 is 0.2-0.8:1, the impregnation temperature is 25-35℃, the impregnation time is 12-24h, and the drying temperature is 80-100℃.

[0022] Preferably, the passivating agent in step (3) is triethanolamine and phytic acid in a mass ratio of 2-3:1, the amount of passivating agent added is 0.05%-0.2% of the mass of product B, the stirring speed is 200-400 rpm, and the stirring time is 5-15 min.

[0023] Preferably, the decolorization and deodorization treatment in step (4) is as follows: add modified porous magnesium silicate and ascorbate palmitate in a mass ratio of 5-10:1 to the crude product, treat it at 60-80℃ for 30-60 min, and then filter it.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) In this invention, phosphotungstic acid supported on amino-modified titanium silicate mesoporous molecular sieve is used as a catalyst. The Ti-SBA-15 support has a regular mesoporous channel structure and Lewis acid centers. The amino modification improves the dispersibility and solid support stability of phosphotungstic acid. The catalyst exhibits excellent catalytic activity and selectivity in the esterification reaction, effectively inhibiting the formation of sorbitol sugar residue and carbon residue, and significantly reducing by-products.

[0025] (2) Before esterification and cooling to prepare the filtration catalyst, a trace amount of triethanolamine-phytic acid alkaline complexing passivator is added in situ. This passivator neutralizes and complexes the free acid centers remaining on the catalyst surface and in the system, cutting off the chain of residual acid continuing to catalyze side reactions at high temperatures, and locking the initial color of the product at an extremely low level (Gardner color ≤ 1.0). At the same time, a low-temperature treatment is carried out using a composite system of modified porous magnesium silicate + ascorbate palmitate. Magnesium silicate efficiently adsorbs pigment precursors, while ascorbate palmitate, as a highly efficient fat-soluble antioxidant, not only quenches the peroxides in the system, but also forms an antioxidant protective layer at the molecular level. Accelerated aging experiments show that the product of this invention, after being stored at 60°C for 15 days (simulating half a year of storage at room temperature), shows almost no change in color. Detailed Implementation

[0026] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0027] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all instruments, devices, equipment, reagents, products, etc., used in the embodiments of the present invention are obtained through conventional commercial means.

[0028] SBA-15 molecular sieve (model: XFF01) was purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.; modified porous magnesium silicate (model: #600 magnesium hexasilicate) was purchased from Zaoyang Yonghua Silicon Magnesium Materials Co., Ltd.; activated carbon (food grade, iodine value ≥900mg / g) was purchased from Jiangsu Zhuxi Activated Carbon Co., Ltd.

[0029] Example 1 A synthetic process for sorbitan monooleate, comprising the following steps: (1) Sorbitol and phosphoric acid (the amount of phosphoric acid is 0.5% of the mass of sorbitol) are mixed and added to a reactor. The mixture is reacted at 130°C and a vacuum of -0.085 MPa for 1.5 h to remove free water and promote intramolecular dehydration of sorbitol to generate sorbitol anhydride, thus obtaining product A.

[0030] (2) Add oleic acid and catalyst a to product A (where the molar ratio of sorbitol to oleic acid is 1:1.2, and the amount of catalyst a is 3% of the total mass of sorbitol and oleic acid), heat to 170℃, react under vacuum of -0.095MPa for 4h, and after the reaction is completed, cool down to 85℃ to obtain product B.

[0031] (3) Add 0.1% of the passivating agent (triethanolamine and phytic acid in a mass ratio of 2:1) to product B, stir at 300 rpm for 10 min for in-situ passivation, and then filter to recover catalyst a to obtain crude product.

[0032] (4) Add 2% of the crude product mass of the composite decolorizing agent (the mass ratio of modified porous magnesium silicate to ascorbate palmitate is 7:1) to the crude product, decolorize and deodorize at 70°C for 45 min, and then filter to obtain sorbitan monooleate.

[0033] The preparation method of catalyst a is as follows: S1. Tetrabutyl titanate was added dropwise to an aqueous dispersion of SBA-15 molecular sieve (the mass ratio of tetrabutyl titanate to SBA-15 molecular sieve was 1:10), and the mixture was hydrothermally reacted at 100℃ for 18 h. After filtration and washing, the mixture was calcined at 550℃ for 4 h to obtain Ti-SBA-15.

[0034] S2. Disperse Ti-SBA-15 in anhydrous toluene, add 15% (by mass) of 3-aminopropyltriethoxysilane (APTES) to Ti-SBA-15, reflux at 100°C for 12 h, filter, wash, and dry to obtain NH2-Ti-SBA-15.

[0035] S3. Impregnate NH2-Ti-SBA-15 in an aqueous solution of phosphotungstic acid (the phosphotungstic acid loading is 30% of the mass of NH2-Ti-SBA-15), stir at room temperature for 18 h, filter, wash, and dry at 90 °C to obtain catalyst a.

[0036] Example 2 A synthetic process for sorbitan monooleate, comprising the following steps: (1) Sorbitol and p-toluenesulfonic acid (the amount of p-toluenesulfonic acid is 0.4% of the mass of sorbitol) are mixed and added to a reactor. The mixture is reacted at 120°C and a vacuum of -0.095 MPa for 2 hours to remove free water and promote intramolecular dehydration of sorbitol to generate sorbitol anhydride, thus obtaining product A.

[0037] (2) Add oleic acid and catalyst a to product A (the molar ratio of sorbitol to oleic acid is 1:1.1, and the amount of catalyst a is 1.5% of the total mass of sorbitol and oleic acid), heat to 160℃, react under vacuum of -0.095MPa for 5h, and after the reaction is completed, cool down to 80℃ to obtain product B.

[0038] (3) Add 0.08% of the passivating agent (triethanolamine and phytic acid in a mass ratio of 2:1) to product B, stir at 300 rpm for 10 min for in-situ passivation, and then filter to recover catalyst a to obtain crude product.

[0039] (4) Add 1.5% of the crude product mass of composite decolorizing agent (the mass ratio of modified porous magnesium silicate to ascorbate palmitate is 6:1) to the crude product, decolorize and deodorize at 60°C for 60 min, and then filter to obtain sorbitan monooleate.

[0040] The preparation method of catalyst a is the same as in Example 1.

[0041] Example 3 A synthetic process for sorbitan monooleate, comprising the following steps: (1) Sorbitol and phosphoric acid (the amount of phosphoric acid is 1.0% of the mass of sorbitol) are mixed and added to a reactor. The mixture is reacted at 140℃ and vacuum degree -0.080MPa for 1h to remove free water and promote intramolecular dehydration of sorbitol to generate sorbitol anhydride, thus obtaining product A.

[0042] (2) Add oleic acid and catalyst a to product A (the molar ratio of sorbitol to oleic acid is 1:1.3, and the amount of catalyst a is 4.5% of the total mass of sorbitol and oleic acid), heat to 180℃, react under vacuum of -0.1MPa for 3h, and after the reaction is completed, cool down to 90℃ to obtain product B.

[0043] (3) Add 0.2% of the passivating agent (triethanolamine and phytic acid in a mass ratio of 2:1) to product B, stir at 300 rpm for 10 min for in-situ passivation, and then filter to recover catalyst a to obtain crude product.

[0044] (4) Add 3% of the crude product mass of the composite decolorizing agent (the mass ratio of modified porous magnesium silicate to ascorbate palmitate is 9:1) to the crude product, decolorize and deodorize at 80°C for 30 min, and then filter to obtain sorbitan monooleate.

[0045] The preparation method of catalyst a is the same as in Example 1.

[0046] Comparative Example 1 This comparative example synthesizes sorbitan monooleate according to the method described in existing technology CN102910994A, specifically as follows: (1) Sorbitol and phosphoric acid (the amount of phosphoric acid is 0.5% of the mass of sorbitol) are added to the reactor, and the temperature is raised to 120°C under vacuum. The etherification reaction is carried out for 70 min to generate dehydrated sorbitol anhydride.

[0047] (2) The dehydrated sorbitan anhydride, oleic acid kept at 120°C and sodium hydroxide as an alkaline catalyst are mixed evenly and esterified at 180°C under vacuum for 3.5 hours to obtain the initial product. The amount of oleic acid added is 150% of the mass of sorbitol and the amount of sodium hydroxide is 0.3% of the total mass of dehydrated sorbitan anhydride and oleic acid.

[0048] (3) After the reaction is complete, cool to room temperature, filter, and obtain crude product.

[0049] (4) The crude product was decolorized with activated carbon at 70°C for 40 min and filtered to obtain sorbitan monooleate.

[0050] Comparative Example 2 The only difference between this comparative example and Example 1 is the preparation method of catalyst a, which is different: S1. Disperse SBA-15 molecular sieve in anhydrous toluene, add 15% by mass of 3-aminopropyltriethoxysilane (APTES) of SBA-15, reflux at 100°C for 12 h, filter and dry to obtain NH2-SBA-15.

[0051] S3. Impregnate NH2-SBA-15 in an aqueous solution of phosphotungstic acid (the phosphotungstic acid loading is 30% of the mass of NH2-SBA-15), stir at room temperature for 18 h, filter, and dry at 90 °C to obtain catalyst a.

[0052] Comparative Example 3 The only difference between this comparative example and Example 1 is the preparation method of catalyst a, which is different: S1. Tetrabutyl titanate was added dropwise to an aqueous dispersion of SBA-15 molecular sieve (Ti / Si molar ratio of 0.08:1), and the mixture was hydrothermally reacted at 100℃ for 18 h. After filtration and washing, the mixture was calcined at 550℃ for 4 h to obtain Ti-SBA-15.

[0053] S2. Impregnate Ti-SBA-15 in an aqueous solution of phosphotungstic acid (the phosphotungstic acid loading is 30% of the mass of Ti-SBA-15), stir at room temperature for 18 h, filter, and dry at 90 °C to obtain catalyst a.

[0054] Comparative Example 4 The only difference between this comparative example and Example 1 is the preparation method of catalyst a, which is different: S1. Tetrabutyl titanate was added dropwise to an aqueous dispersion of SBA-15 molecular sieve (the mass ratio of tetrabutyl titanate to SBA-15 molecular sieve was 1:10), and the mixture was hydrothermally reacted at 100℃ for 18 h. After filtration and washing, the mixture was calcined at 550℃ for 4 h to obtain Ti-SBA-15.

[0055] S2. Disperse Ti-SBA-15 in anhydrous ethanol, add 15% (by mass) of ethylenediamine to Ti-SBA-15, stir and physically impregnate at 80°C for 12 h, filter and dry to obtain NH2-Ti-SBA-15.

[0056] S3. Impregnate NH2-Ti-SBA-15 in an aqueous solution of phosphotungstic acid (the phosphotungstic acid loading is 30% of the mass of NH2-Ti-SBA-15), stir at room temperature for 18 h, filter, and dry at 90 °C to obtain catalyst a.

[0057] Comparative Example 5 The only difference between this comparative example and Example 1 is that step (3) is different; in-situ passivation is not performed. Specifically: Product B was filtered to recover catalyst a, yielding a crude product.

[0058] Comparative Example 6 The only difference between this comparative example and Example 1 is that modified porous magnesium silicate and ascorbate palmitate are not added in step (4), but an equal mass of conventional activated carbon is added, specifically: Add 2% (by weight of crude product) of activated carbon to the crude product, decolorize and deodorize at 70°C for 45 min, and then filter to obtain sorbitan monooleate.

[0059] Effect test Test Example 1 Initial Performance Test The contents of monooleate, dioleate and trioleate were determined by liquid chromatography (HPLC), and the test results are shown in Table 1.

[0060] Table 1

[0061] The monooleate content in Examples 1-3 of this invention was 76.8%-78.5%, the dioleate content was 14.2%-15.5%, and the trioleate content was 5.3%-5.7%. Compared with Comparative Example 1, the monooleate content increased by approximately 14-16 percentage points, while the dioleate and trioleate contents decreased by approximately 7-8 percentage points and 5-6 percentage points, respectively. This indicates that the "amino-modified titanium silicate mesoporous molecular sieve supported phosphotungstic acid catalyst + two-step ether-then-ester method" used in this invention can effectively suppress the deep esterification of sorbitan anhydride and significantly improve the monooleate selectivity.

[0062] Compared with Comparative Examples 2-4, it can be seen that when the catalyst lacks titanium doping (Comparative Example 2), lacks amino modification (Comparative Example 3), or uses a non-silane coupling agent ethylenediamine for simple physical impregnation (Comparative Example 4), the monoester content of the obtained product is significantly lower than that of Example 1. This indicates that the introduction of Ti establishes Lewis acidic centers, while the APTES chemically bonded amino groups achieve highly dispersed immobilization of phosphotungstic acid. Both are indispensable and together constitute a highly efficient acid-base bifunctional catalytic system.

[0063] Test Example 2: Accelerated Aging Color Reversion Test Gardner colorimetry was determined according to GB / T 9282 standard. The finished products obtained from each example and comparative example were placed in sealed transparent glass bottles and stored in a 60°C oven for 15 days (this condition is equivalent to simulating storage at room temperature in the dark for half a year). After being taken out, Gardner colorimetry was measured again, and the colorimetry increase value (color recovery degree) was calculated.

[0064] The test results are shown in Table 2.

[0065] Table 2

[0066] The initial Gardner chromaticity of Examples 1-3 of this invention was 0.8-1.0. After accelerated aging at 60°C for 15 days, the chromaticity was 1.0-1.2, and the chromaticity increase (ΔE) was only 0.2, indicating that the chromaticity of the product hardly changed under simulated room temperature storage conditions for half a year.

[0067] This invention employs "in-situ passivation termination" and "composite decolorizing agent to prevent color reversion," addressing the product color problem from two different dimensions: "eliminating residual catalyst activity" and "inhibiting oxidative color reversion reaction." Both are indispensable, and together they achieve the comprehensive effect of "extremely low initial color and no color reversion during long-term storage."

[0068] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A process for the synthesis of sorbitan monooleate, characterized in that, Includes the following steps: (1) Sorbitol was mixed with an etherification catalyst and subjected to a first-stage dehydration reaction to obtain product A; (2) Add oleic acid and catalyst a to product A to carry out the second stage of esterification reaction, cool down, and obtain product B; (3) Add passivating agent to product B, stir, filter, and obtain crude product; (4) The crude product was decolorized and deodorized to obtain sorbitan monooleate; The preparation method of catalyst a includes the following steps: S1. Add the titanium source to the aqueous dispersion of SBA-15 molecular sieve, perform hydrothermal reaction, filter, wash, dry, and calcine to obtain Ti-SBA-15; S2. Disperse Ti-SBA-15 in anhydrous toluene, add 3-aminopropyltriethoxysilane to react, filter, wash, and dry to obtain NH2-Ti-SBA-15; S3. Impregnate NH2-Ti-SBA-15 in an aqueous solution of phosphotungstic acid, filter, wash, and dry to obtain catalyst a.

2. The process for synthesis of sorbitan monooleate according to claim 1, characterized in that, The etherification catalyst in step (1) is selected from at least one of phosphoric acid, p-toluenesulfonic acid, phosphorous acid and sulfuric acid. The amount of the etherification catalyst is 0.2%-3.0% of the mass of sorbitol. The temperature of the first stage dehydration reaction is 120-140℃ and the reaction time is 1-3h.

3. The process for synthesis of sorbitan monooleate as claimed in claim 1, wherein, In step (2), the molar ratio of oleic acid to sorbitol is 1-1.8:1, and the amount of catalyst a is 1%-5% of the total mass of sorbitol and oleic acid.

4. The process for synthesis of sorbitan monooleate as claimed in claim 1, wherein, The conditions for the second stage esterification reaction in step (2) include: a temperature of 160-200℃, a vacuum of -0.08~-0.1MPa, and a reaction time of 3-5h; the cooling temperature is 80-90℃.

5. The process for synthesis of sorbitan monooleate as claimed in claim 1, wherein, The titanium source mentioned in step S1 is tetrabutyl titanate or titanium tetrachloride, and the mass ratio of the titanium source to SBA-15 molecular sieve is 1:5-20.

6. The synthesis process of sorbitan monooleate according to claim 5, characterized in that, The hydrothermal reaction in step S1 is carried out at a temperature of 95-105℃ for 12-24 hours, and the calcination temperature is 400-600℃ for 2-6 hours.

7. The synthesis process of sorbitan monooleate according to claim 1, characterized in that, In step S2, the mass ratio of 3-aminopropyltriethoxysilane to Ti-SBA-15 is 0.2-0.5:1, the reaction temperature is 80-120℃, and the reaction time is 6-24h.

8. The synthesis process of sorbitan monooleate according to claim 1, characterized in that, In step S3, the mass ratio of phosphotungstic acid to NH2-Ti-SBA-15 is 0.2-0.8:1, the impregnation temperature is 25-35℃, the impregnation time is 12-24h, and the drying temperature is 80-100℃.

9. The synthesis process of sorbitan monooleate according to claim 1, characterized in that, The passivating agent in step (3) is triethanolamine and phytic acid in a mass ratio of 2-3:

1. The amount of passivating agent added is 0.05%-0.2% of the mass of product B. The stirring speed is 200-400 rpm and the stirring time is 5-15 min.

10. The synthesis process of sorbitan monooleate according to any one of claims 1-9, characterized in that, The decolorization and deodorization process in step (4) is as follows: add modified porous magnesium silicate and ascorbate palmitate in a mass ratio of 5-10:1 to the crude product, treat it at 60-80℃ for 30-60 min, and then filter it.

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