Sulfonated silica gel catalyst, preparation method thereof and application of sulfonated silica gel catalyst in olefin hydroesterification reaction

Abstract

The invention belongs to the technical field of olefin hydroesterification reaction and catalysts thereof, and particularly relates to a sulfonated silica gel catalyst, a preparation method thereof and application of the sulfonated silica gel catalyst in olefin hydroesterification reaction. The preparation method of the sulfonated silica gel catalyst comprises the following steps: adding an acid solution into a silica gel precursor solution to adjust the pH value, carrying out heating reaction, adding a surfactant and stirring, adding an alkali solution to adjust the pH value, stirring and hydrolyzing to form gel, drying and roasting to obtain porous silica gel; adding a sulfonating agent into the porous silica gel under a stirring condition to obtain sulfonated silica gel; the preparation method comprises the following steps: weighing Pd salt and a P complex, dissolving the Pd salt and the P complex in an impregnation solution by adopting an equivalent-volume impregnation method, adding sulfonated silica gel for impregnation, and drying the impregnated sulfonated silica gel to obtain the sulfonated silica gel catalyst. According to the preparation method of the sulfonated silica gel catalyst provided by the invention, the prepared catalyst has the advantages of small corrosion to equipment, easiness in product separation, mild reaction conditions, wide raw material application range and high product selectivity.

Description

Technical Field

[0001] The invention belongs to the technical field of olefin hydroesterification reaction and catalysts thereof, and specifically relates to a sulfonated silica gel catalyst and a preparation method thereof, and application thereof in olefin hydroesterification reaction. Background Art

[0002] At present, the methoxycarbonylation of olefins or alkynes has attracted wide attention. In this reaction, unsaturated hydrocarbons react with CO and oxygen-containing nucleophiles (such as methanol and water) under the action of a catalyst to generate corresponding carboxylic acid derivatives. The metal complexes that catalyze this reaction mainly include complexes of Ru, Pd, Pt, and Co. Among them, Pd / P complexes catalyze the methoxycarbonylation reaction under mild conditions, and can obtain higher reaction activity and selectivity, so they are widely concerned and studied. For example, CN114621089A discloses a method for preparing methyl propionate, using Ru-modified molecular sieves as catalysts, and the catalytic efficiency is high. An important application of the methoxycarbonylation reaction is the alkoxycarbonylation of aromatic substituted alkenes and alkynes, and its reaction products are precursors of important categories of non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, ketoprofen and naproxen. Since these products are used as drugs, they are required to be completely free of metal catalysts. In addition, since the catalysts of its reactions use precious metals as main catalysts, they are expensive. Therefore, higher requirements are put forward for the stability, separation effect and recycling of the catalyst. In the prior art, efforts are made to find appropriate catalyst separation and recycling methods.

[0003] The most widely used catalyst system in industry is to use methanesulfonic acid as an acid promoter and ethylene as a probe to evaluate the reaction of the reactants. When using methanesulfonic acid as a promoter to catalyze the hydroesterification of ethylene to prepare methyl propionate, the reaction yield of the catalyst can reach more than 90%. However, methanesulfonic acid is highly corrosive and has high requirements for equipment. In addition, the boiling point of methanesulfonic acid is about 64°C, which is close to that of methanol. Methanol easily forms an azeotrope with methyl propionate, resulting in increased separation energy consumption of the reaction.

[0004] To solve the above problems, CN102531890A discloses a method for preparing organic carboxylic acid esters by olefin hydroesterification reaction, using acidic ionic liquid to replace methanesulfonic acid for hydroesterification reaction. Although its reaction performance is good, the preparation method of ionic liquid is complicated and the cost is high, which is not economically advantageous.

[0005] Therefore, it is of great significance to develop a new type of acid auxiliary agent for olefin hydroesterification reaction which has little corrosion to equipment, is easy to separate, has a simple preparation method and low cost. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the above prior art and provide a method for preparing a sulfonated silica gel catalyst. The prepared catalyst has low corrosion to equipment and is easy to separate the product. It is used in the preparation of organic carboxylic acid esters by olefin hydroesterification reaction. The reaction conditions are mild, the raw materials have a wide range of applicability, and the product selectivity is high.

[0007] The preparation method of the sulfonated silica gel catalyst of the present invention comprises the following steps:

[0008] (1) adding an acid solution to a silica gel precursor solution to adjust the pH to 3-6, heating and stirring to react, adding a surfactant and stirring, then adding an alkali solution and adjusting the pH to 8-12, stirring and hydrolyzing to form a gel, and drying and calcining to obtain a porous silica gel;

[0009] (2) adding a sulfonating agent to the porous silica gel under stirring conditions, and performing a sulfonation reaction until the acid amount is 2-7 mol / g to obtain sulfonated silica gel; after sulfonation, the acid equivalent is determined by acid-base titration, and the acid amount is calculated as the amount of sulfonate groups; the sulfonation time is 2-12 h;

[0010] (3) Using an equal volume impregnation method, weighing Pd salt and P complex, dissolving them in an impregnation solution, then adding sulfonated silica gel for impregnation, and drying the impregnated sulfonated silica gel to obtain a sulfonated silica gel catalyst.

[0011] The impregnation solution in step (3) is one of methanol, ethanol, deionized water and toluene, wherein the sulfonated silica gel is dried at a temperature of 50-120° C. for a time of 4-6 hours.

[0012] The silica precursor of step (1) is one of tetraethyl orthosilicate, methyl orthosilicate, and butyl orthosilicate; the surfactant is one of polyethylene glycol, P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer), and cellulose.

[0013] The acid solution in step (1) is one or more of hydrochloric acid, sulfuric acid, oxalic acid, and citric acid solutions, and the pH of the acid solution is between 1 and 5. The alkaline solution in step (1) is ammonia water or sodium hydroxide solution.

[0014] The sulfonating agent in step (2) is concentrated sulfuric acid or chlorosulfonic acid.

[0015] The Pd salt in step (3) is one of Pd(OAc)2, PdCl2, Pd(dba)2, and palladium trifluoroacetate, and the P ligand is one of PPh3, 1,2-bis[(di-tert-butylphosphino)methyl]benzene, tri-n-butylphosphine, tri(4-fluorophenyl)phosphine, and diphenyl-2-pyridylphosphine.

[0016] Step (1) is heated to 30-80°C, preferably 30-50°C, the stirring time is 10-60min, the hydrolysis time is 3-6h, the drying temperature is 60-120°C, the drying time is 4-6h, the roasting temperature is 250-450°C, and the roasting time is 4-6h.

[0017] The mass ratio of the silica precursor to the surfactant in step (1) is (1-100): (1-5).

[0018] The molar ratio of the porous silica gel in step (2) to the sulfonating agent is (5-10):(1-5) based on silicon oxide.

[0019] In step (3), the Pd loading of the sulfonated silica gel catalyst accounts for 0.01-0.5% of the mass of the sulfonated silica gel catalyst; the loading amount of the P complex, calculated by the mass of P, accounts for 0.1-1% of the mass of the sulfonated silica gel catalyst.

[0020] The specific surface area of ​​the sulfonated silica catalyst obtained in step (3) is 150-350cm 3 / g, pore size is 3-20nm.

[0021] A sulfonated silica gel catalyst is prepared by the preparation method of the sulfonated silica gel catalyst.

[0022] An application of the sulfonated silica gel catalyst in the hydroesterification reaction of olefins comprises the following steps: mixing alcohol and sulfonated silica gel catalyst, sealing, filling with terminal olefin, pressurizing to 1-10 MPa, heating to 50-180°C, reacting for 2-10 hours, preferably 4-6 hours; wherein the mass ratio of alcohol to sulfonated silica gel catalyst is (50-500): (0.1-1), and the amount of terminal olefin added per kettle is 0.06-5 mol. The terminal olefin is one of ethylene, propylene, butylene, butadiene, and styrene, and the mass purity of the olefin is 90-100%. The alcohol is one of methanol, ethanol, ethylene glycol, and glycerol, and the alcohol compound is also used as the solvent of the reaction system.

[0023] The pressurization uses CO or a mixture of CO and N2, wherein the mass purity of CO or the mixture of CO and N2 is 90-100%.

[0024] Specifically, the use of the sulfonated silica gel catalyst in the olefin hydroesterification reaction comprises the following steps:

[0025] (1) Add silica gel precursor (tetraethyl orthosilicate, methyl orthosilicate, butyl orthosilicate) into a round-bottom flask, add water according to the mass ratio of water to silica gel precursor (1-6):1, then add acid solution (hydrochloric acid, sulfuric acid, oxalic acid, citric acid solution), adjust the pH to 3-6, raise the temperature to 30-80°C and stir to react for 10-60 minutes, add surfactant (polyethylene glycol, P123, cellulose) and stir, then add alkaline solution (ammonia water or sodium hydroxide solution), adjust the pH to 8-12, stir and hydrolyze for 3-6 hours to form a gel, dry at 60-120°C for 4-6 hours, and calcine at 250-450°C for 4-6 hours to obtain porous silica gel.

[0026] (2) Under stirring conditions, porous silica gel is placed in a round-bottom flask, and a sulfonating agent (concentrated sulfuric acid or chlorosulfonic acid) is added dropwise using a constant pressure dropping funnel. After the addition is completed, the reaction is carried out for 2-12 hours, and the sulfonation reaction is carried out until the acid content is 2-7 mol / g to obtain sulfonated silica gel; after sulfonation, the acid equivalent is determined by acid-base titration, and the acid content is calculated as the amount of sulfonate groups.

[0027] (3) Using an equal volume impregnation method, weigh Pd salt and P complex and dissolve them in an impregnation solution (methanol, ethanol, deionized water, toluene), then add sulfonated silica gel for impregnation, and dry the impregnated sulfonated silica gel at 50-120° C. to obtain a sulfonated silica gel catalyst. The Pd loading amount accounts for 0.01-0.5% of the mass of the sulfonated silica gel catalyst; the P complex loading amount, calculated by the mass of P, accounts for 0.1-1% of the mass of the sulfonated silica gel catalyst.

[0028] (4) In a 250 ml high-pressure reactor, methanol and sulfonated silica catalyst were added in sequence. The reactor was sealed, and the reactor was replaced with CO for three times. Terminal olefins were introduced, and then CO or a mixture of CO and N2 was introduced until the pressure of the reactor was 1-10 MPa. The temperature was slowly raised to 50-180°C by a temperature controller, and the reaction was carried out for 4-6 hours. The reaction was cooled to room temperature, the reactor was unloaded, and the liquid obtained by the reaction was quantitatively analyzed using Agilent 6890.

[0029] The present invention generates an organic carboxylic acid ester with one more carbon by using terminal olefins, CO and alcohol compounds under the action of a catalyst composed of a Pd compound, a phosphine ligand and sulfonated silica gel. The present invention has the advantages of mild reaction conditions, a wide range of raw material applications, and high product selectivity. Compared with the current hydroesterification reaction, the catalyst system used has the advantages of low equipment corrosion and easy product separation, and is a catalyst with great industrial application prospects.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The preparation method of the sulfonated silica gel catalyst of the present invention loads the precious metal Pd and the P complex, and the catalyst is non-volatile, low in corrosiveness, and causes little damage to the equipment.

[0032] (2) The sulfonated silica gel catalyst of the present invention is used in the hydroesterification reaction of olefins. The sulfonate groups in the sulfonated silica gel provide hydrogen ions, and the reaction activity and selectivity are relatively high. In addition, the heterogeneous acid auxiliary agent is beneficial to the separation between the reaction raw materials and the products, thereby reducing the separation energy consumption and realizing the recovery and reuse of the catalyst.

[0033] (3) The sulfonated silica gel catalyst prepared by the method of the present invention has strong structural adjustability. The pore structure and acid content of the sulfonated silica gel can be adjusted according to the requirements of the reaction to optimize the reaction results. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific embodiments.

[0035] In the following examples and comparative examples, the mass purity of the alcohol is 90%-100%, the mass purity of CO or the mixed gas of CO and N2 is 90%-100%, and the other chemical reagents used are all commercially available products, and the equipment used is all existing equipment. The acid equivalent is measured by acid-base titration after sulfonation, and the acid amount is measured by the amount of sulfonate. The conventional operation steps are not further described.

[0036] Example 1

[0037] The use of the sulfonated silica gel catalyst in the olefin hydroesterification reaction comprises the following steps:

[0038] (1) Add 20 g of tetraethyl orthosilicate into a round-bottom flask, add water according to the mass ratio of water to silica gel precursor of 4:1, then add hydrochloric acid, adjust the pH to 5, raise the temperature to 30°C and stir to react for 60 min, add 4 g of cellulose and stir, then add ammonia water and adjust the pH to 8, stir and hydrolyze for 4 h to form a gel, dry at 60°C for 6 h, and calcine at 350°C for 4 h to obtain porous silica gel.

[0039] (2) Under stirring conditions, 20 g of porous silica gel was placed in a round-bottom flask, and 2 g of chlorosulfonic acid was added dropwise using a constant pressure dropping funnel. After the addition was completed, the reaction was carried out for 3 hours, and the sulfonation reaction was carried out until the acid content was 4 mmol / g to obtain sulfonated silica gel.

[0040] (3) Using the equal volume impregnation method, 25 mg of Pd(OAc)2 and 1 g of PPh3 were weighed and dissolved in toluene, and then 10 g of sulfonated silica gel was added for impregnation. The impregnated sulfonated silica gel was dried at 80°C for 6 h to obtain a sulfonated silica gel catalyst. According to ICP detection, the Pd loading in the catalyst accounted for 0.01% of the mass of the sulfonated silica gel catalyst; according to NMR P spectrum analysis, PPh3, calculated by the mass of P, accounted for 1% of the mass of the sulfonated silica gel catalyst.

[0041] (4) In a 250 ml autoclave, 100 g of methanol and 2 g of sulfonated silica gel catalyst were added in sequence. The autoclave was sealed and replaced with CO for three times. 0.06 mol of ethylene was introduced and CO was then introduced until the pressure of the autoclave reached 4 MPa. The temperature was slowly raised to 100°C by a temperature controller. The reaction was continued for 2 h. The autoclave was cooled to room temperature and the autoclave was unloaded. The liquid obtained by the reaction was quantitatively analyzed using an Agilent 6890.

[0042] Example 2

[0043] The use of the sulfonated silica gel catalyst in the olefin hydroesterification reaction comprises the following steps:

[0044] (1) 1 g of methyl orthosilicate was added to a round-bottom flask, and water was added according to the mass ratio of water to silica gel precursor of 6:1. Then, hydrochloric acid was added to adjust the pH to 3, and the temperature was raised to 50°C and stirred for 30 min. 100 g of polyethylene glycol was added and stirred, and then ammonia water was added to adjust the pH to 10. The mixture was stirred and hydrolyzed for 6 h to form a gel, which was dried at 80°C for 4 h and calcined at 250°C for 6 h to obtain porous silica gel.

[0045] (2) Under stirring conditions, 20 g of porous silica gel was placed in a round-bottom flask, and 20 g of concentrated sulfuric acid was added dropwise using a constant pressure dropping funnel. After the addition was completed, the reaction was carried out for 6 hours, and the sulfonation reaction was carried out until the acid content was 6 mmol / g to obtain sulfonated silica gel.

[0046] (3) By using the equal volume impregnation method, 125 mg of PdCl2 and 15 g of diphenyl-2-pyridylphosphine were weighed and dissolved in methanol, and then 10 g of sulfonated silica gel was added for impregnation. The impregnated sulfonated silica gel was dried at 80°C for 6 h to obtain a sulfonated silica gel catalyst. According to ICP detection, the Pd loading amount accounted for 0.5% of the mass of the sulfonated silica gel catalyst; according to NMR P spectrum analysis, the diphenyl-2-pyridylphosphine accounted for 0.8% of the mass of the sulfonated silica gel catalyst in terms of the mass of P.

[0047] (4) In a 250 ml autoclave, 250 g of methanol and 0.05 g of sulfonated silica gel catalyst were added in sequence. The autoclave was sealed and replaced with CO for three times. 0.1 mol of ethylene was charged into the autoclave and CO was then charged until the pressure of the autoclave reached 1 MPa. The temperature was slowly raised to 180°C by a temperature controller. The reaction was continued for 10 h. The autoclave was cooled to room temperature and the autoclave was unloaded. The liquid obtained by the reaction was quantitatively analyzed using an Agilent 6890.

[0048] Example 3

[0049] The use of the sulfonated silica gel catalyst in the olefin hydroesterification reaction comprises the following steps:

[0050] (1) Add 5 g of butyl orthosilicate into a round-bottom flask, add water according to the mass ratio of water to silica gel precursor 2:1, then add oxalic acid, adjust the pH to 6, heat to 80 ° C and stir for 10 min, add 5 g of P123 and stir, then add ammonia water and adjust the pH to 12, stir and hydrolyze for 3 h to form a gel, dry at 120 ° C for 6 h, and calcine at 450 ° C for 4 h to obtain porous silica gel.

[0051] (2) Under stirring conditions, 20 g of porous silica gel was placed in a round-bottom flask, and 4 g of concentrated sulfuric acid was added dropwise using a constant pressure dropping funnel. After the addition was complete, the reaction was allowed to proceed for 2 h, and the sulfonation reaction was performed until the acid content reached 2 mmol / g to obtain sulfonated silica gel.

[0052] (3) Using the equal volume impregnation method, 80 mg of Pd(dba)2 and 5 g of 1,2-bis[(di-tert-butylphosphino)methyl]benzene were weighed and dissolved in methanol, and then 10 g of sulfonated silica gel was added for impregnation. The impregnated sulfonated silica gel was dried at 100°C for 6 h to obtain a sulfonated silica gel catalyst. According to ICP detection, the Pd loading amount accounted for 0.25% of the mass of the sulfonated silica gel catalyst; according to NMR P spectrum analysis, 1,2-bis[(di-tert-butylphosphino)methyl]benzene accounted for 0.1% of the mass of the sulfonated silica gel catalyst based on the mass of P.

[0053] (4) In a 250 ml autoclave, 100 g of methanol and 2 g of sulfonated silica catalyst were added in sequence. The autoclave was sealed and replaced with CO for three times. 1 mol of ethylene was introduced and then a mixture of CO and N2 was introduced until the pressure of the autoclave reached 10 MPa. The temperature was slowly raised to 50°C by a temperature controller. The reaction was continued for 6 h. The autoclave was cooled to room temperature and the autoclave was unloaded. The liquid obtained by the reaction was quantitatively analyzed using Agilent 6890.

[0054] Example 4

[0055] The use of the sulfonated silica gel catalyst in the olefin hydroesterification reaction comprises the following steps:

[0056] (1) 20 g of butyl orthosilicate was added to a round-bottom flask, and water was added according to the mass ratio of water to silica gel precursor of 1:1. Then, citric acid solution was added, and the pH was adjusted to 5. The temperature was raised to 60°C and stirred for reaction for 30 min. 1 g of cellulose was added and stirred. Then, sodium hydroxide solution was added and the pH was adjusted to 10. The mixture was stirred and hydrolyzed for 5 h to form a gel. The mixture was dried at 60°C for 6 h and calcined at 350°C for 4 h to obtain porous silica gel.

[0057] (2) Under stirring conditions, 20 g of porous silica gel was placed in a round-bottom flask, and 8 g of chlorosulfonic acid was added dropwise using a constant pressure dropping funnel. After the addition was complete, the reaction was carried out for 2-12 hours, and the sulfonation reaction was carried out until the acid content was 7 mmol / g to obtain sulfonated silica gel.

[0058] (3) By using an equal volume impregnation method, 90 mg of palladium trifluoroacetate and 10 g of tri-n-butylphosphine were weighed and dissolved in toluene, and then 10 g of sulfonated silica gel was added for impregnation. The impregnated sulfonated silica gel was dried at 80° C. for 6 h to obtain a sulfonated silica gel catalyst. According to ICP detection, the Pd loading amount accounted for 0.15% of the mass of the sulfonated silica gel catalyst; according to nuclear magnetic resonance P spectrum analysis, the mass of P in tri-n-butylphosphine accounted for 0.6% of the mass of the sulfonated silica gel catalyst.

[0059] (4) In a 250 ml autoclave, 100 ml of methanol and 1 g of sulfonated silica catalyst were added in sequence. The autoclave was sealed and replaced with CO for three times. 0.1 mol of ethylene was introduced and CO was then introduced until the pressure of the autoclave reached 4 MPa. The temperature was slowly raised to 100 °C by a temperature controller. The reaction was continued for 4 h. The autoclave was cooled to room temperature and the autoclave was unloaded. The liquid obtained by the reaction was quantitatively analyzed using an Agilent 6890.

[0060] Comparative Example 1

[0061] A method for preparing ethylene by olefin hydroesterification reaction comprises the following steps:

[0062] In a 250ml autoclave, add 0.05mmol PdCl2(PPh3)2 and 100mL methanol in sequence, seal the autoclave, replace the autoclave with CO for 3 times, flush in 0.6mol ethylene, and then fill in CO gas until the pressure of the autoclave is 4MPa. The temperature is slowly raised to 80℃ by the temperature controller, react for 10h, cool to room temperature, unload the autoclave, and quantitatively analyze the liquid obtained by the reaction using Agilent 6890.

[0063] Comparative Example 2

[0064] A method for preparing ethylene by olefin hydroesterification reaction comprises the following steps:

[0065] In a 250ml high-pressure reactor, 0.05mmol Pd(OAc)2, 0.5mmol methanesulfonic acid, 0.4mmol 1,2-bis[(di-tert-butylphosphino)methyl]benzene, and 100mL methanol were added in sequence. The reactor was sealed, and the reactor was replaced with CO for 3 times. 0.2mol ethylene was flushed into the reactor, and then CO gas was filled into the reactor until the pressure of the reactor was 3Mpa. The temperature was slowly raised to 80°C by a temperature controller. The reaction was carried out for 6h, cooled to room temperature, and the reactor was unloaded. The liquid obtained by the reaction was quantitatively analyzed by Agilent 6890.

[0066] Comparative Example 3

[0067] Compared with Example 1, no cellulose surfactant was added, and other conditions were the same. According to ICP detection, the Pd loading amount accounted for 0.01% of the mass of the sulfonated silica gel catalyst; according to NMR P spectrum analysis, the mass of tri-n-butylphosphine accounted for 0.02% of the mass of the sulfonated silica gel catalyst based on the mass of P.

[0068] Comparative Example 4

[0069] Compared with Example 1, the amount of chlorosulfonic acid added was 1 g, and other conditions were the same. According to ICP detection, the Pd loading amount accounted for 0.005% of the mass of the sulfonated silica gel catalyst; according to NMR P spectrum analysis, the mass of tri-n-butylphosphine, calculated by the mass of P, accounted for 0.008% of the mass of the sulfonated silica gel catalyst.

[0070] Comparative Example 5

[0071] Compared with Example 1, the amount of chlorosulfonic acid added was 30 g, and other conditions were the same. ICP detection showed that Pd was not loaded on the silica gel; and NMR P spectrum analysis showed that no phosphine spectrum signal was detected.

[0072] Comparative Example 6

[0073] Compared with Example 1, the silicon source was replaced with sodium silicate, and other conditions were the same. ICP detection showed that Pd was not loaded on the silica gel; and NMR P spectrum analysis showed that no phosphine spectrum signal was detected.

[0074] After analyzing the above Examples 1-4 and Comparative Examples 1-6, the conversion rate of ethylene and the selectivity of methyl propionate are shown in Table 1.

[0075] Table 1 Analysis results of Examples 1-4 and Comparative Examples 1-6

[0076] project Ethylene conversion rate / % Selectivity of methyl propionate / % Example 1 98％ 99％ Example 2 99％ 98％ Example 3 98％ 99％ Example 4 97％ 99％ Comparative Example 1 Not Detected - Comparative Example 2 90％ 89％ Comparative Example 3 50％ 79％ Comparative Example 4 35％ 64％ Comparative Example 5 0 0 Comparative Example 6 0 0

[0077] The catalyst used in Example 1 was centrifuged and then added to the reactor. Other conditions remained unchanged. After the reaction was continued for 2 hours, the reaction was cooled to room temperature, the reactor was unloaded, and the liquid obtained by the reaction was quantitatively analyzed using Agilent 6890. The above steps were repeated 10 times. The ethylene conversion rate and the selectivity of the product methyl propionate are shown in Table 2.

[0078] Table 2 Repeatability test results

[0079] project Ethylene conversion Selectivity of methyl propionate Example 1-1 98％ 99％ Example 1-2 98％ 98％ Examples 1-3 98％ 98％ Examples 1-4 97％ 99％ Examples 1-5 97％ 98％ Examples 1-6 98％ 98％ Examples 1-7 98％ 97％ Examples 1-8 98％ 98％ Examples 1-9 97％ 97％ Examples 1-10 97％ 97％

[0080] The catalysts prepared in the examples and comparative examples were subjected to BET testing, and the test results are shown in Table 3.

[0081] Table 3 Catalyst test results

[0082]

[0083]

[0084] Of course, the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and equal changes and improvements made by ordinary technicians in the technical field within the essential scope of the present invention should all fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a sulfonated silica gel catalyst, characterized in that: The following steps are involved: (1) adding an acid solution to a silica gel precursor solution to adjust the pH to 3-6, heating and stirring to react, adding a surfactant and stirring, then adding an alkali solution and adjusting the pH to 8-12, stirring and hydrolyzing to form a gel, and drying and calcining to obtain a porous silica gel; (2) adding a sulfonating agent to the porous silica gel under stirring conditions, and performing a sulfonation reaction until the acid content is 2-7 mol / g to obtain a sulfonated silica gel; (3) Using an equal volume impregnation method, weighing Pd salt and P complex, dissolving them in an impregnation solution, then adding sulfonated silica gel for impregnation, and drying the impregnated sulfonated silica gel to obtain a sulfonated silica gel catalyst.

2. The method for preparing a sulfonated silica gel catalyst according to claim 1, characterized in that: The silica precursor of step (1) is one of tetraethyl orthosilicate, methyl orthosilicate and butyl orthosilicate; the surfactant is one of polyethylene glycol, P123 and cellulose.

3. The method for preparing a sulfonated silica gel catalyst according to claim 1, characterized in that: The sulfonating agent in step (2) is concentrated sulfuric acid or chlorosulfonic acid.

4. The method for preparing a sulfonated silica gel catalyst according to claim 1, characterized in that: The Pd salt in step (3) is one of Pd(OAc)2, PdCl2, Pd(dba)2, and palladium trifluoroacetate, and the P ligand is one of PPh3, 1,2-bis[(di-tert-butylphosphino)methyl]benzene, tri-n-butylphosphine, tri(4-fluorophenyl)phosphine, and diphenyl-2-pyridylphosphine.

5. The method for preparing a sulfonated silica gel catalyst according to claim 1, characterized in that: Step (1) is heated to 30-80°C, stirred for 10-60 minutes, hydrolyzed for 3-6 hours, dried at 60-120°C, dried for 4-6 hours, and calcined at 250-450°C, for 4-6 hours.

6. The method for preparing a sulfonated silica gel catalyst according to claim 1, characterized in that: The mass ratio of the silica precursor to the surfactant in step (1) is (1-100): (1-5).

7. The method for preparing a sulfonated silica gel catalyst according to claim 1, characterized in that: The mass ratio of the porous silica gel in step (2) to the sulfonating agent is (5-10):(1-5) based on silicon oxide.

8. The method for preparing a sulfonated silica gel catalyst according to claim 1, characterized in that: In step (3), the Pd loading of the sulfonated silica gel catalyst accounts for 0.01-0.5% of the mass of the sulfonated silica gel catalyst; the loading amount of the P complex, calculated by the mass of P, accounts for 0.1-1% of the mass of the sulfonated silica gel catalyst.

9. A sulfonated silica catalyst, characterized in that: The sulfonated silica gel catalyst is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the sulfonated silica gel catalyst according to claim 9, characterized in that: The application in olefin hydroesterification reaction comprises the following steps: mixing alcohol and sulfonated silica gel catalyst, sealing, filling with terminal olefin, pressurizing to 1-10MPa, heating to 50-180°C, and reacting for 2-10h; wherein the mass ratio of alcohol to sulfonated silica gel catalyst is (50-500): (0.1-1), and the single-pot addition amount of terminal olefin is 0.06-5mol.

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