Supported esterification catalyst, its preparation method and application in synthesis of cyclohexyl acetate

Abstract

This invention relates to the field of fine chemical technology, and discloses a supported esterification catalyst, its preparation method, and its application in the synthesis of cyclohexyl acetate. The supported esterification catalyst includes a support and an active component supported on the support; the support is an SBA-16 all-silica mesoporous molecular sieve, and the active component is a Lewis acid; based on the total weight of the supported esterification catalyst, the content of the support is 60-90% by weight, and the content of the active component is 10-40% by weight. This supported esterification catalyst, when used in the synthesis of cyclohexyl acetate, can achieve a higher esterification rate.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, specifically to a supported esterification catalyst, its preparation method, and its application in the synthesis reaction of cyclohexyl acetate. Background Technology

[0002] Cyclohexyl acetate, also known as cyclohexyl acetate, is a colorless or slightly yellow transparent oily liquid with a banana or apple aroma. It is an important flavoring agent in the food industry, commonly used to formulate flavors such as apple, banana, blackcurrant, and raspberry, and is widely used in beverages, ice cream, and other foods. It is also a commonly used fragrance in the daily cosmetics industry. Furthermore, due to its good solubility in resins, it is often used as a solvent in coatings and paints. Industrially, acetic acid and cyclohexanol are commonly used as raw materials, with concentrated sulfuric acid as a catalyst to synthesize cyclohexyl acetate. However, because cyclohexanol is a secondary alcohol, it easily dehydrates to form cyclohexene under the action of concentrated sulfuric acid, reducing the esterification rate. In addition, using concentrated sulfuric acid as a catalyst also has disadvantages such as severe equipment corrosion, complex post-processing, and environmental pollution. p-Toluenesulfonic acid is a common and readily available strong organic acid that can be used in esterification reactions. Compared with concentrated sulfuric acid, p-toluenesulfonic acid has advantages such as high activity, good selectivity, high product purity, high yield, no equipment corrosion, and reduced pollution. However, p-Toluenesulfonic acid is readily soluble in water, alcohols, and ethers, and is extremely hygroscopic with poor water resistance, which affects its application in catalytic esterification.

[0003] To overcome the shortcomings of inorganic and organic esterification catalysts, much research has been conducted in recent years on novel esterification catalysts such as inorganic salts, ion exchange resins, solid superacids, and molecular sieves. The esterification reaction mode has also shifted from homogeneous to heterogeneous reactions. Solid catalysts exhibit advantages such as good stability, high selectivity, low cost, and ease of separation in esterification reactions. However, these catalysts have relatively slow reaction rates and low ester yields. Cation exchange resins also exhibit advantages such as good stability, high selectivity, low cost, and ease of separation in esterification reactions. However, cation exchange resins themselves have poor heat resistance (generally suitable for esterification reactions below 150℃), small specific surface area and pore volume, and are prone to swelling, resulting in poor reactivity and low ester yields as esterification catalysts. Compared with resin catalysts, hydrogen-form zeolite molecular sieves possess certain pore structures and surface acidity, making them suitable for catalyzing the esterification reactions of small molecules. However, zeolite molecular sieves have relatively small pore sizes (0.5-0.7 nm), which may inhibit the diffusion of macromolecular products during the reaction; moreover, the number of acidic sites on the surface of zeolite molecular sieves is relatively small, resulting in low efficiency in catalyzing esterification reactions. Therefore, directly applying hydrogen-form zeolite molecular sieve materials to the synthesis of cyclohexyl acetate is also impractical.

[0004] With the increasing demand for cyclohexyl acetate, the green and environmentally friendly synthesis process for cyclohexyl acetate shows great promise. For researchers, developing high-performance catalysts for the synthesis of cyclohexyl acetate, improving reaction efficiency, and suppressing byproduct formation are important directions for future work. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of excessive side reactions and severe environmental pollution caused by inorganic acid catalysts used in current cyclohexyl acetate production processes, as well as the poor catalytic activity and low esterification rates of solid acid catalysts and acidic cation exchange resin catalysts. This invention provides a supported esterification catalyst, its preparation method, and its application in the synthesis of cyclohexyl acetate. This supported esterification catalyst, when used in the synthesis of cyclohexyl acetate, can achieve a higher esterification rate.

[0006] To achieve the above objectives, a first aspect of the present invention provides a supported esterification catalyst, wherein the supported esterification catalyst comprises a support and an active component supported on the support; the support is an SBA-16 all-silica mesoporous molecular sieve, and the active component is a Lewis acid; and based on the total weight of the supported esterification catalyst, the content of the support is 60-90% by weight, and the content of the active component is 10-40% by weight.

[0007] The second aspect of the present invention provides a method for preparing the aforementioned supported esterification catalyst, wherein the preparation method comprises: reacting SBA-16 all-silica mesoporous molecular sieve with an aqueous solution of active component and allowing it to stand; and then subjecting it to dehydration, drying and calcination to obtain the supported esterification catalyst.

[0008] A third aspect of the present invention provides the application of the aforementioned supported esterification catalyst in the synthesis reaction of cyclohexyl acetate.

[0009] Compared with the prior art, the technical solution of the present invention has the following advantages through the above technical solution:

[0010] (1) The supported esterification catalyst support provided by the present invention is a large-pore mesoporous material with stable structure and good high temperature resistance, which helps the diffusion of raw material and product molecules during the esterification reaction.

[0011] (2) The surface active components of the supported esterification catalyst provided by the present invention are uniformly dispersed, with strong esterification catalytic ability and high esterification rate.

[0012] (3) The supported esterification catalyst provided by the present invention has readily available raw materials, a simple preparation method, easy-to-control conditions, and good product repeatability.

[0013] (4) The supported esterification catalyst provided by the present invention has mild process conditions and low requirements for reaction equipment when used in the synthesis reaction of cyclohexyl acetate.

[0014] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0015] Figure 1 This is the XRD pattern of the SBA-16 all-silica mesoporous molecular sieve A prepared in Example 1;

[0016] Figure 2 These are TEM images of the SBA-16 all-silica mesoporous molecular sieve A prepared in Example 1;

[0017] Figure 3 This is the XRD pattern of the supported esterification catalyst A prepared in Example 1. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] As previously stated, the first aspect of the present invention provides a supported esterification catalyst, wherein the supported esterification catalyst comprises a support and an active component supported on the support; the support is an SBA-16 all-silica mesoporous molecular sieve, and the active component is a Lewis acid; and based on the total weight of the supported esterification catalyst, the content of the support is 60-90% by weight, and the content of the active component is 10-40% by weight.

[0020] The inventors of this invention have discovered that, in the prior art, esterification catalysts used for the production of cyclohexyl acetate are divided into two categories: homogeneous catalysts and heterogeneous catalysts. Homogeneous catalysts mainly include inorganic acid solutions and organic acids, while heterogeneous catalysts mainly include solid acids and cation exchange resins. Homogeneous catalysts have the advantages of low cost and good catalytic activity; however, they are gradually being phased out due to drawbacks such as difficulty in separating the product from the catalyst, numerous side reactions, and easy corrosion of equipment. Solid esterification catalysts, although solving the problems of difficult product separation and severe equipment corrosion, are rarely used in industrial production due to their poor catalytic activity, high reaction temperature, and low product selectivity. Compared with the above catalysts, resin catalysts have advantages such as high selectivity, low cost, and easy separation; however, they exhibit a lower esterification rate in the cyclohexyl acetate synthesis reaction and poor high-temperature resistance. Resins are organic polymers that easily swell in organic solvents and are prone to deformation or even decomposition in high-temperature environments, which is the main reason for the poor temperature resistance of resin catalysts.

[0021] Lewis acid catalysts exhibit high activity, good selectivity, and mild reaction conditions in esterification reactions; however, they are prone to deactivation due to hydrolysis. This problem can be solved by selecting a suitable support to effectively disperse the Lewis acid catalyst, thereby improving catalyst efficiency. All-silica mesoporous molecular sieve materials possess structural advantages such as large specific surface area, large pore volume, and high-temperature resistance. However, silica, with its basic framework structure composed of silicon and oxygen, lacks functional groups and shows no activity in esterification reactions. The inventors of this invention unexpectedly discovered that by utilizing the structural advantages of all-silica mesoporous inorganic materials as supports for esterification catalysts, and loading Lewis acids with good esterification activity (e.g., tin tetrachloride, stannous chloride, zinc sulfate, zinc chloride, etc.), esterification catalysts with superior catalytic performance can be obtained. This catalyst exhibits excellent catalytic activity and achieves a high esterification rate in acetic acid esterification reactions.

[0022] According to the present invention, preferably, based on the total weight of the supported esterification catalyst, the content of the support is 65-85% by weight, and the content of the active component is 15-35% by weight; more preferably, based on the total weight of the supported esterification catalyst, the content of the support is 69.3-80.8% by weight, and the content of the active component is 19.2-30.7% by weight. In the present invention, by using the aforementioned specific content of the support and the content of the active component, the prepared supported esterification catalyst can exhibit better catalytic activity and a higher esterification rate when used in the synthesis reaction of cyclohexyl acetate.

[0023] According to the present invention, the active component is selected from one or more of tin tetrachloride, stannous chloride, zinc sulfate and zinc chloride; preferably, the active component is tin tetrachloride.

[0024] According to the present invention, the specific surface area of ​​the supported esterification catalyst is 300-800 m². 2 The pore volume is 0.3-0.8 ml / g, and the average pore size is 4-7 nm; preferably, the specific surface area of ​​the supported esterification catalyst is 400-700 m² / g. 2 The pore volume is 0.4-0.7 ml / g, and the average pore size is 4.5-6.5 nm; more preferably, the supported esterification catalyst has a specific surface area of ​​437-669 m² / g. 2 / g, pore volume is 0.45-0.62ml / g, and average pore size is 4.8-6.2nm.

[0025] According to the present invention, the specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 600-1000 m². 2 / g, pore volume of 0.4-1.0ml / g, and average pore size of 5-8nm; preferably, the specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 700-900m². 2 The SBA-16 all-silica mesoporous molecular sieve has a pore volume of 0.5-0.8 ml / g and an average pore size of 5.5-7.5 nm; more preferably, the specific surface area of ​​the SBA-16 is 749-853 m² / g. 2 The pore volume is 0.6-0.7 ml / g, and the average pore size is 6.0-7.0 nm. In this invention, the use of a support with the aforementioned specific parameters enables the prepared catalyst to exhibit better catalytic activity and a higher esterification rate when used in the synthesis reaction of cyclohexyl acetate.

[0026] According to the present invention, the preparation method of the SBA-16 all-silica mesoporous molecular sieve includes:

[0027] (1) Mix the template agent, acidic aqueous solution, n-butanol and chitosan to obtain a mixture;

[0028] (2) The mixture is reacted with a silicon source, then allowed to stand for crystallization and separation to obtain a solid product;

[0029] (3) The solid product is washed, dried and calcined to obtain SBA-16 all-silica mesoporous molecular sieve.

[0030] According to the present invention, the template agent can be an amphoteric triblock polymer, preferably F127 (polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, molecular formula EO). 106 PO 70 EO 106 ).

[0031] According to the present invention, the acidic aqueous solution can be an inorganic acid aqueous solution, preferably one or more of dilute hydrochloric acid or dilute nitric acid, more preferably dilute hydrochloric acid; the concentration of the acidic aqueous solution can be 0.2-10%, preferably 0.5-3%.

[0032] According to the present invention, the silicon source can be an organic silicon-containing compound or an inorganic silicon-containing compound, preferably one or more of methyl orthosilicate, ethyl orthosilicate, isopropyl orthosilicate or silica sol, and more preferably ethyl orthosilicate.

[0033] According to the present invention, the weight ratio of the template agent: acidic aqueous solution: n-butanol: chitosan: silicon source can be 1:(10-200):(0.2-10):(0.05-1.0):(1-8), preferably 1:(20-100):(0.5-3):(0.1-0.5):(2-4).

[0034] According to the present invention, the mixing conditions include: a stirring rate of 50-300 r / min, a temperature of 20-60°C, and a time of 0.5-6 h; preferably, the stirring rate is 150-250 r / min, the temperature is 20-40°C, and the time is 0.5-3 h.

[0035] According to the present invention, the conditions for the contact reaction can be a temperature of 50-150°C, preferably 80-120°C; and a time of 3-40 h, preferably 10-20 h.

[0036] According to the present invention, the conditions for static crystallization can be a temperature of 50-150°C, preferably 80-120°C; and a time of 10-48h, preferably 16-30h.

[0037] According to the present invention, there are no special requirements for the solid-liquid two-phase separation process, and it can be a separation method known in the art, including gravity filtration, pressure filtration, vacuum filtration, or centrifugal filtration. Preferably, the separation process specifically includes: using a vacuum flask to create a vacuum at the bottom of a funnel or using a centrifugal filter.

[0038] According to the present invention, there are no special requirements for the method of washing the solid product. For example, deionized water can be used to wash the solid product, the volume ratio of deionized water to solid product can be 5-20, and the number of washing cycles can be 2-8.

[0039] According to the present invention, the drying conditions can be a temperature of 80-150°C, preferably 100-130°C; and a time of 2-30 hours, preferably 5-20 hours.

[0040] According to the present invention, the calcination conditions can be a temperature of 400-700℃, preferably 500-600℃; and a time of 2-24h, preferably 4-12h.

[0041] The second aspect of the present invention provides a method for preparing the aforementioned supported esterification catalyst, wherein the preparation method comprises: reacting SBA-16 all-silica mesoporous molecular sieve with an aqueous solution of active component and allowing it to stand; and then subjecting it to dehydration, drying and calcination to obtain the supported esterification catalyst.

[0042] According to the present invention, the mass concentration of the aqueous solution of the active component (Lewis acid) is 2-50%.

[0043] According to the present invention, the weight ratio of the SBA-16 all-silica mesoporous molecular sieve to the aqueous solution of the active component can be 1:(0.2-20), preferably 1:(0.5-10).

[0044] According to the present invention, the conditions for the contact reaction include: a temperature of 10-100°C, preferably 20-80°C; and a time of 0.5-50 h, preferably 2-20 h. Preferably, to achieve better mixing, rapid stirring or ultrasonic means can be used to improve mixing efficiency during the mixing of the SBA-16 all-silica mesoporous molecular sieve and the aqueous solution of the active component (tin tetrachloride).

[0045] According to the present invention, the water removal method is not particularly limited and can be any water removal method known in the art, such as using a rotary evaporator to evaporate water or using a heating and stirring method to remove water.

[0046] According to the present invention, the drying conditions include: a temperature of 60-150°C, preferably 90-120°C; and a time of 1-30 hours, preferably 3-20 hours.

[0047] According to the present invention, the calcination conditions include: a temperature of 200-600℃, preferably 250-400℃; and a time of 1-20h, preferably 3-10h.

[0048] A third aspect of the present invention provides the application of the aforementioned supported esterification catalyst in the synthesis reaction of cyclohexyl acetate.

[0049] According to the present invention, the reaction comprises: simultaneously contacting acetic acid and cyclohexanol with a supported esterification catalyst to react.

[0050] In this invention, the contact conditions between acetic acid and cyclohexanol and the catalyst include: the contact temperature can be 70-130℃, preferably 80-110℃; the weight ratio of acetic acid:cyclohexanol:catalyst:hydrophoretic agent cyclohexane is 1:1-10:0.01-0.1:0.5-8, preferably 1:2-4:0.02-0.05:1-3; the reaction time can be 0.5-8h, preferably 1-3h.

[0051] The present invention will be described in detail below through embodiments.

[0052] In the following examples and comparative examples:

[0053] Small-angle XRD tests of the samples were performed on a BRUKER AXS D8 ADVANCE high-power rotating target X-ray diffractometer, with a scanning range of 0.5-10°.

[0054] The pore structure parameters of the samples were analyzed using an ASAP2020-M+C adsorption analyzer manufactured by Micromeritics, USA. Before measurement, the samples were degassed under vacuum at 350℃ for 4 hours. The specific surface area of ​​the samples was calculated using the BET method, and the pore volume was calculated using the BJH model.

[0055] Elemental analysis of the samples was performed on an Eagle III energy-dispersive X-ray fluorescence spectrometer manufactured by EDAX Corporation in the United States.

[0056] The rotary evaporator was manufactured by IKA GmbH in Germany, and its model number is RV10 digital.

[0057] The drying oven was manufactured by Shanghai Yiheng Scientific Instruments Co., Ltd., model DHG-9030A.

[0058] The muffle furnace is manufactured by CARBOLITE, model CWF1100.

[0059] All reagents used in the examples and comparative examples were purchased from Sinopharm Chemical Reagent Co., Ltd., and the reagent purity was analytical grade.

[0060] Example 1

[0061] (1) Preparation of SBA-16 all-silica mesoporous molecular sieve

[0062] In a 1000ml round-bottom flask, add 10g of polyether F127, 20g of concentrated hydrochloric acid, and 500ml of deionized water, and mix and stir at room temperature for 30 minutes. Continue by adding 15g of n-butanol and 2g of chitosan to the flask, and stir for 1 hour. Slowly add 25g of tetraethyl orthosilicate, raise the temperature to 100℃, and stir and react for 16 hours. Then, allow the mixture to crystallize at 100℃ for 24 hours. After crystallization, filter to obtain a white solid product, wash 8 times with deionized water, dry in air at 120℃ for 10 hours, and then calcine at 550℃ for 8 hours to obtain SBA-16 mesoporous molecular sieve A.

[0063] The specific surface area of ​​SBA-16 mesoporous molecular sieve A is 794 m². 2 / g, pore volume 0.65cm³ 3 / g, with an average pore size of 6.5nm.

[0064] Figure 1 This is the XRD pattern of SBA-16 all-silica mesoporous molecular sieve A. From... Figure 1 The spectrum shows that the sample has a strong diffraction peak and a weak shoulder peak in the range of 2θ = 0.5°-1°, which are attributed to the characteristic diffraction peaks of the (110) crystal plane and the (200) crystal plane, respectively, indicating that SBA-16 all-silica mesoporous molecular sieve A has a relatively regular Im3m body-centered cubic mesoporous structure.

[0065] Figure 2 This is a TEM image of SBA-16 all-silica mesoporous molecular sieve A. From Figure 2 It can be seen that the mesoporous structure of SBA-16 all-silica mesoporous molecular sieve A is regularly arranged, with a cubic structure and a pore spacing of 7-8 nm.

[0066] (2) Preparation of supported esterification catalysts

[0067] 74g of SBA-16 all-silica mesoporous molecular sieve A and 130g of tin tetrachloride aqueous solution (mass concentration of 20%) were mixed and stirred at 60℃ for 8h, then allowed to stand at 60℃ for 2h. The water was evaporated using a rotary evaporator, dried at 100℃ for 10h, and calcined at 300℃ for 5h to obtain supported esterification catalyst A.

[0068] Based on the total weight of catalyst A, the content of SBA-16 all-silica mesoporous molecular sieve A is 74.2% by weight, and the content of tin tetrachloride is 25.8% by weight.

[0069] The specific surface area of ​​supported esterification catalyst A is 624 m². 2 / g, pore volume 0.57cm³ 3 / g, with an average pore size of 5.6nm.

[0070] Figure 3 This is the XRD pattern of supported esterification catalyst A. From... Figure 3 The spectrum shows that the catalyst exhibits strong diffraction signals corresponding to the (110) crystal plane in the range of 2θ = 0.5°-1°, indicating that the SBA-16 all-silica mesoporous molecular sieve still retains a relatively regular mesoporous channel structure after loading the active component, and the loading process did not destroy the basic structure of the mesoporous molecular sieve. The diffraction peak intensity of catalyst A is lower than that of SBA-16 all-silica mesoporous molecular sieve A, which is due to the active component covering the surface of the molecular sieve or entering the molecular sieve channels.

[0071] (3) Evaluation of catalyst reaction performance

[0072] 10g acetic acid, 26g cyclohexanol, 0.25g supported esterification catalyst A, and 18g cyclohexane (a dehydrating agent) were added to a 200mL four-necked flask. A thermometer, water separator, and condenser were attached. The mixture was heated under reflux for 2 hours, cooled to room temperature, and allowed to stand for 3 hours. After the solid catalyst settled, the organic layer was transferred. The fraction collected at 168-172℃ was distilled to obtain colorless, transparent, and fragrant cyclohexyl acetate. The acid value before and after the reaction was determined according to GB / T 1668-1995. The esterification rate was calculated using the following formula: Esterification rate = (1 - acid value after reaction / acid value before reaction) × 100%.

[0073] Evaluation results of the supported esterification catalyst A: esterification rate was 99.0%.

[0074] Example 2

[0075] (1) Preparation of SBA-16 all-silica mesoporous molecular sieve

[0076] In a 1000ml round-bottom flask, add 10g of polyether F127 and 200g of 3% dilute hydrochloric acid, and mix and stir at room temperature for 30 minutes. Continue by adding 5g of n-butanol and 1g of chitosan to the flask, and stir for 1 hour. Slowly add 20g of tetraethyl orthosilicate, raise the temperature to 80℃, and stir and react for 20 hours. Then, allow the mixture to crystallize at 80℃ for 30 hours. After crystallization, filter to obtain a white solid product, wash six times with deionized water, dry in air at 100℃ for 20 hours, and then calcine at 500℃ for 12 hours to obtain SBA-16 mesoporous molecular sieve B.

[0077] The specific surface area of ​​SBA-16 mesoporous molecular sieve B is 853 m². 2 / g, pore volume 0.7cm³ 3 / g, with an average pore size of 6.0nm.

[0078] (2) Preparation of supported esterification catalysts

[0079] 80g of SBA-16 all-silica mesoporous molecular sieve B and 390g of tin tetrachloride aqueous solution (mass concentration of 10%) were mixed and stirred at 80℃ for 4h, then allowed to stand at 80℃ for 3h. The water was evaporated using a rotary evaporator, dried at 120℃ for 3h, and calcined at 400℃ for 3h to obtain the supported esterification catalyst B.

[0080] Based on the total weight of the supported esterification catalyst B, the content of SBA-16 all-silica mesoporous molecular sieve B is 80.8% by weight, and the content of tin tetrachloride is 19.2% by weight.

[0081] The specific surface area of ​​supported esterification catalyst B is 669 m². 2 / g, pore volume is 0.62cm³ 3 / g, with an average pore size of 4.8nm.

[0082] (3) Evaluation of catalyst reaction performance

[0083] The esterification performance of the supported esterification catalyst B was tested according to step (3) in Example 1. The esterification rate was 98.6%.

[0084] Example 3

[0085] (1) Preparation of SBA-16 all-silica mesoporous molecular sieve

[0086] In a 2000ml round-bottom flask, 10g of polyether F127 and 200g of 0.5% dilute hydrochloric acid were added and stirred at room temperature for 30 minutes. Then, 30g of n-butanol and 5g of chitosan were added, and the mixture was stirred for 1 hour. 40g of tetraethyl orthosilicate was slowly added, and the temperature was raised to 120℃. After stirring and reacting for 10 hours, the mixture was allowed to crystallize at 120℃ for 16 hours. After crystallization, the product was filtered to obtain a white solid product, washed 8 times with deionized water, dried in air at 130℃ for 5 hours, and then calcined at 600℃ for 4 hours to obtain SBA-16 mesoporous molecular sieve C.

[0087] The specific surface area of ​​SBA-16 mesoporous molecular sieve C is 749 m². 2 / g, pore volume 0.6cm³ 3 / g, with an average pore size of 7.0nm.

[0088] (2) Preparation of supported esterification catalysts

[0089] 70g of SBA-16 all-silica mesoporous molecular sieve C and 110g of tin tetrachloride aqueous solution (mass concentration of 30%) were mixed and stirred at 40℃ for 10h, then allowed to stand at 40℃ for 2h. The water was evaporated using a rotary evaporator, dried at 90℃ for 20h, and calcined at 250℃ for 10h to obtain the supported esterification catalyst C.

[0090] Based on the total weight of the supported esterification catalyst C, the SBA-16 all-silica mesoporous molecular sieve contains 69.3% C by weight and 30.7% tin tetrachloride by weight.

[0091] The specific surface area of ​​the supported esterification catalyst C is 437 m². 2 / g, pore volume 0.45cm³ 3 / g, with an average pore size of 6.2nm.

[0092] (3) Evaluation of catalyst reaction performance

[0093] The esterification performance of the supported esterification catalyst C was tested according to step (3) in Example 1. The esterification rate was 98.4%.

[0094] Example 4

[0095] The supported esterification catalyst D was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0096] 85g of SBA-16 all-silica mesoporous molecular sieve A and 75g of tin tetrachloride aqueous solution (mass concentration of 20%) were mixed and stirred at 60℃ for 8h, then allowed to stand at 60℃ for 2h. The water was evaporated using a rotary evaporator, dried at 100℃ for 10h, and calcined at 300℃ for 5h to obtain the supported esterification catalyst D.

[0097] Based on the total weight of the supported esterification catalyst D, the content of SBA-16 all-silica mesoporous molecular sieve A is 85% by weight, and the content of tin tetrachloride is 15% by weight. The specific surface area of ​​the supported esterification catalyst D is 686 m². 2 / g, pore volume is 0.63cm³ 3 / g, with an average pore size of 6.3nm.

[0098] The catalytic performance of the supported esterification catalyst D was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The esterification rate was 97.2%.

[0099] Example 5

[0100] The supported esterification catalyst E was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0101] 65g of SBA-16 all-silica mesoporous molecular sieve A and 175g of tin tetrachloride aqueous solution (mass concentration of 20%) were mixed and stirred at 60℃ for 8h, then allowed to stand at 60℃ for 2h. The water was evaporated using a rotary evaporator, dried at 100℃ for 10h, and calcined at 300℃ for 5h to obtain the supported esterification catalyst E.

[0102] Based on the total weight of the supported esterification catalyst E, the content of SBA-16 all-silica mesoporous molecular sieve A is 65 wt%, and the content of tin tetrachloride is 35 wt%. The specific surface area of ​​the supported esterification catalyst E is 428 m². 2 / g, pore volume is 0.44cm³ 3 / g, with an average pore size of 4.9nm.

[0103] The catalytic performance of the supported esterification catalyst E was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The esterification rate was 97.0%.

[0104] Example 6

[0105] The supported esterification catalyst F was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0106] 90g of SBA-16 all-silica mesoporous molecular sieve A and 100g of zinc sulfate aqueous solution (mass concentration of 10%) were mixed and stirred at 60℃ for 8h, then allowed to stand at 60℃ for 2h. The water was evaporated using a rotary evaporator, dried at 100℃ for 10h, and calcined at 300℃ for 5h to obtain the supported esterification catalyst F.

[0107] Based on the total weight of the supported esterification catalyst F, the content of SBA-16 all-silica mesoporous molecular sieve A is 90 wt%, and the content of zinc sulfate is 10 wt%. The specific surface area of ​​the supported esterification catalyst F is 738 m². 2 / g, pore volume is 0.64cm³ 3 / g, with an average pore size of 6.4nm.

[0108] The catalytic performance of the supported esterification catalyst F was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The esterification rate was 96.0%.

[0109] Example 7

[0110] The supported esterification catalyst G was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0111] 60g of SBA-16 all-silica mesoporous molecular sieve A and 160g of tin tetrachloride aqueous solution (mass concentration of 25%) were mixed and stirred at 60℃ for 8h, then allowed to stand at 60℃ for 2h. The water was evaporated using a rotary evaporator, dried at 100℃ for 10h, and calcined at 300℃ for 5h to obtain the supported esterification catalyst G.

[0112] Based on the total weight of the supported esterification catalyst G, the content of SBA-16 all-silica mesoporous molecular sieve A is 60 wt%, and the content of tin tetrachloride is 40 wt%. The specific surface area of ​​the supported esterification catalyst G is 391 m². 2 / g, pore volume is 0.38cm³ 3 / g, with an average pore size of 4.2nm.

[0113] The catalytic performance of the supported esterification catalyst G was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The esterification rate was 96.3%.

[0114] Comparative Example 1

[0115] The supported esterification catalyst D1 was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0116] 95g of SBA-16 all-silica mesoporous molecular sieve A and 170g of tin tetrachloride aqueous solution (mass concentration of 3%) were mixed and stirred at 60℃ for 8h, then allowed to stand at 60℃ for 2h. The water was evaporated using a rotary evaporator, dried at 100℃ for 10h, and calcined at 300℃ for 5h to obtain catalyst D1.

[0117] Based on the total weight of catalyst D1, the content of SBA-16 all-silica mesoporous molecular sieve A is 95.1% by weight, and the content of tin tetrachloride is 4.9% by weight.

[0118] The catalytic performance of catalyst D1 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The esterification rate was 91.6%.

[0119] Comparative Example 2

[0120] The supported esterification catalyst D2 was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0121] 48g of SBA-16 all-silica mesoporous molecular sieve A and 130g of stannous chloride ethanol solution (mass concentration of 40%) were mixed and stirred at 60℃ for 8h, then allowed to stand at 60℃ for 2h. The ethanol solvent was evaporated using a rotary evaporator, dried at 100℃ for 10h, and calcined at 300℃ for 5h to obtain catalyst D2.

[0122] Based on the total weight of catalyst D2, the content of SBA-16 all-silica mesoporous molecular sieve A is 48% by weight, and the content of stannous chloride is 52% by weight.

[0123] The catalytic performance of catalyst D2 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The esterification rate was 92.1%.

[0124] Comparative Example 3

[0125] The supported esterification catalyst D2 was prepared using the same method as in Example 1, except that step (1) in Example 1 was omitted, and the SBA-16 all-silica mesoporous molecular sieve A in step (2) of Example 1 was replaced with commercially available silica (purchased from Qingdao Hailang Silica Gel Desiccant Factory, with a specific surface area of ​​329 m²). 2 Catalyst D3 was obtained by using a pore volume of 0.4 ml / g and an average pore diameter of 15 nm.

[0126] Based on the total weight of catalyst D3, the content of commercially available silica is 74.2% by weight and the content of tin tetrachloride is 25.8% by weight.

[0127] The catalytic performance of catalyst D3 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The esterification rate was 90.2%.

[0128] Comparative Example 4

[0129] The supported esterification catalyst D2 was prepared in the same manner as in Example 1, except that step (1) in Example 1 was omitted and sodium sulfate was replaced with tin tetrachloride in step (2) of Example 1 to obtain catalyst D4.

[0130] Based on the total weight of catalyst D4, the content of SBA-16 all-silica mesoporous molecular sieve A is 74.2% by weight, and the content of sodium sulfate is 25.8% by weight.

[0131] The catalytic performance of catalyst D4 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The esterification rate was 67.4%.

[0132] The results above show that the supported esterification catalyst provided by the present invention can directly convert acetic acid and cyclohexanol into cyclohexyl acetate, resulting in a high esterification rate of cyclohexyl acetate.

[0133] In Comparative Example 1, the content of SBA-16 all-silica mesoporous molecular sieve A was too high. Due to the low content of tin tetrachloride, an active component on the catalyst, and insufficient active sites during the reaction, the esterification rate was low.

[0134] In Comparative Example 2, the content of SBA-16 all-silica mesoporous molecular sieve A was too low. Due to the uneven dispersion of the active component tin tetrachloride on the catalyst and the poor catalytic efficiency of the active sites during the reaction, the esterification rate was low.

[0135] In Comparative Example 3, the carrier specifically defined in this invention was not used; instead, commercially available silica was used. Due to the irregular pore structure of commercially available silica and the uneven dispersion of the active components on the carrier surface, the esterification rate was low.

[0136] In Comparative Example 4, sodium sulfate was used instead of the active component specifically defined in this invention. Because the esterification catalytic performance of sodium sulfate by the same weight is far lower than that of tin tetrachloride, the esterification rate was lower.

[0137] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. The application of a supported esterification catalyst in the synthesis reaction of cyclohexyl acetate, wherein the application includes: Acetic acid and cyclohexanol are simultaneously contacted with a supported esterification catalyst; characterized in that the supported esterification catalyst comprises a support and an active component supported on the support; the support is an SBA-16 all-silica mesoporous molecular sieve, and the active component is a Lewis acid selected from one or more of stannous tetrachloride, stannous chloride, zinc sulfate, and zinc chloride; and based on the total weight of the supported esterification catalyst, the content of the support is 60-90% by weight, and the content of the active component is 10-40% by weight. The specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 600-1000 m². 2 / g, pore volume is 0.4-1.0ml / g, and average pore size is 5-8nm.

2. The application according to claim 1, wherein, Based on the total weight of the supported esterification catalyst, the content of the support is 65-85% by weight, and the content of the active component is 15-35% by weight.

3. The application according to claim 2, wherein, Based on the total weight of the supported esterification catalyst, the content of the support is 69.3-80.8% by weight, and the content of the active component is 19.2-30.7% by weight.

4. The application according to claim 1, wherein, The active component is tin tetrachloride.

5. The application according to claim 1, wherein, The supported esterification catalyst has a specific surface area of ​​300-800 m². 2 / g, pore volume is 0.3-0.8ml / g, and average pore size is 4-7nm.

6. The application according to claim 5, wherein, The supported esterification catalyst has a specific surface area of ​​400-700 m². 2 / g, pore volume is 0.4-0.7ml / g, and average pore size is 4.5-6.5nm.

7. The application according to claim 6, wherein, The supported esterification catalyst has a specific surface area of ​​437-669 m². 2 / g, pore volume is 0.45-0.62ml / g, and average pore size is 4.8-6.2nm.

8. The application according to claim 1, wherein, The specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 700-900 m². 2 / g, pore volume is 0.5-0.8ml / g, and average pore size is 5.5-7.5nm.

9. The application according to claim 8, wherein, The specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 749-853 m². 2 / g, pore volume is 0.6-0.7ml / g, and average pore size is 6.0-7.0nm.

10. The application according to claim 1, wherein, The preparation method of the SBA-16 all-silica mesoporous molecular sieve includes: (1) Mix the template agent, acidic aqueous solution, n-butanol and chitosan to obtain a mixture; (2) The mixture is reacted with a silicon source, then allowed to stand for crystallization and separation to obtain a solid product; (3) The solid product is washed, dried and calcined to obtain SBA-16 all-silica mesoporous molecular sieve.

11. The application according to claim 10, wherein, The weight ratio of the template agent, acidic aqueous solution, n-butanol, chitosan, and silicon source is 1:(10-200):(0.2-10):(0.05-1.0):(1-8). And / or, the conditions for contacting the mixture with a silicon source include: a temperature of 50-150°C for 3-40 hours; And / or, the crystallization conditions include: a temperature of 50-150°C and a time of 10-48 hours; And / or, the calcination conditions include: a temperature of 400-700℃ and a time of 2-24h.

12. The application according to any one of claims 1-11, wherein, The preparation method of the supported esterification catalyst includes: reacting SBA-16 all-silica mesoporous molecular sieve with an aqueous solution of active component and allowing it to stand; then removing water, drying and calcining to obtain the supported esterification catalyst.

13. The application according to claim 12, wherein, The weight ratio of the SBA-16 all-silica mesoporous molecular sieve to the aqueous solution of the active component is 1:(0.2-20).

14. The application according to claim 13, wherein, The weight ratio of the SBA-16 all-silica mesoporous molecular sieve to the aqueous solution of the active component is 1:(0.5-10).

15. The application according to claim 12, wherein, The conditions for contacting SBA-16 all-silica mesoporous molecular sieve with the aqueous solution of active component include: temperature of 10-100℃ and time of 0.5-50h. And / or, the calcination conditions for reacting SBA-16 all-silica mesoporous molecular sieve with an aqueous solution of active components and then calcining include: a temperature of 200-600℃ and a time of 1-20h.

16. The application according to claim 1, wherein, The conditions for simultaneously contacting acetic acid and cyclohexanol with a supported esterification catalyst include: a temperature of 70-130℃ and a time of 0.5-8h. And / or, the weight ratio of the acetic acid, the cyclohexanol and the supported esterification catalyst is 1:(1-10):(0.01-0.1).

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