Supported acidic catalyst and preparation method and application thereof

Abstract

The invention relates to the field of fine chemical engineering, in particular to a supported acid catalyst and a preparation method and application thereof. The catalyst comprises a carrier and an active component loaded on the carrier; wherein the carrier is a mesoporous carbon material, and the active component is lanthanum p-toluenesulfonate; on the basis of the total weight of the supported acidic catalyst, the content of the mesoporous carbon material is 25 to 55 weight percent, preferably 31 to 49 weight percent, more preferably 35 to 44 weight percent, and the content of the lanthanum p-toluenesulfonate is 45 to 75 weight percent, preferably 51 to 69 weight percent, and more preferably 56 to 65 weight percent. The supported acidic catalyst provided by the invention is stable in structure, good in high temperature resistance, non-toxic, free of deformation and swelling in the reaction process, easy to recover after the reaction, mild in process condition and low in requirement on a reaction device when being used for an oleate synthesis reaction. The oleic acid conversion rate is high and the oleate selectivity is high.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, specifically to a supported acidic catalyst and its preparation method, as well as the application of the catalyst in the synthesis reaction of oleate esters. Background Technology

[0002] Methyl oleate is an important organic chemical product, mainly used as a basic raw material for surfactants, a leather and rubber softener, a lubricant for non-fluorescent drilling mud in oil exploration, a plasticizer, a water-resistant agent, and a toughening agent for resins. It is also frequently used in organic synthesis. In addition, methyl oleate can be used as an intermediate in detergents, emulsifiers, wetting agents, and stabilizers, widely used in various emulsified products, as well as as a solvent for fragrances and a lubricant for aerosol products. Currently, the traditional industrial process for producing methyl oleate uses inorganic or organic acids (such as concentrated sulfuric acid, concentrated hydrochloric acid, or p-toluenesulfonic acid) as catalysts to catalyze the esterification reaction of oleic acid and methanol to produce methyl oleate. Inorganic or organic acid catalysts have the advantage of low cost, but they also have disadvantages such as serious environmental pollution, high requirements for equipment materials, numerous side reactions, many by-products, and difficulties in separating and purifying the obtained product. In recent years, my country's oleate production technology has been continuously developing, and the production capacity of oleate has been continuously improving. The use of solid acids or cation exchange resins as catalysts for the synthesis of methyl oleate has seen significant development and has been widely applied in industrial production. Solid catalysts exhibit advantages such as good stability, high selectivity, low cost, and easy 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 easy 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 supported acidic catalysts. Compared with resin catalysts, hydrogen-form zeolite molecular sieves possess a certain pore structure and surface acidity, making them suitable for catalyzing esterification reactions. However, the pore size of zeolite molecular sieves is small (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 lower efficiency in catalyzing esterification reactions. With the increasing demand for methyl oleate, the synthesis of methyl oleate using green and environmentally friendly processes has a promising future.

[0003] Currently, supported esterification catalysts are receiving increasing attention in ester synthesis reactions. For researchers, developing high-performance esterification catalysts to improve reaction efficiency and suppress byproduct formation is an important direction for future work. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of excessive side reactions and serious environmental pollution caused by homogeneous acid catalysts used in current oleate production processes, as well as the poor catalytic activity and low ester selectivity of solid acid catalysts and acidic cation exchange resin catalysts. A supported acid catalyst is provided for the synthesis of oleate esters, which can achieve higher oleic acid conversion and oleate ester selectivity.

[0005] To achieve the above objectives, a first aspect of the present invention provides a supported acidic catalyst, the catalyst comprising a support and an active component supported on the support;

[0006] The support is a mesoporous carbon material, and the active component is lanthanum p-toluenesulfonate. Based on the total weight of the supported acidic catalyst, the content of the mesoporous carbon material is 25-55 wt%, preferably 31-49 wt%, more preferably 35-44 wt%, and the content of the lanthanum p-toluenesulfonate is 45-75 wt%, preferably 51-69 wt%, more preferably 56-65 wt%.

[0007] A second aspect of the present invention provides a method for preparing the supported acidic catalyst, comprising the following steps:

[0008] (1) Mix mesoporous carbon material and lanthanum salt, and then ball mill them to obtain a catalyst intermediate;

[0009] (2) The catalyst intermediate is reacted with an aqueous solution of p-toluenesulfonic acid to obtain a solid product, which is then washed, dried and calcined to obtain the supported acid catalyst.

[0010] A third aspect of the invention provides the application of the supported acidic catalyst in the synthesis reaction of oleate esters.

[0011] A fourth aspect of the present invention provides a method for preparing an oleic acid ester, the method comprising: reacting oleic acid, a lower alcohol, and a catalyst.

[0012] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0013] 1. The supported acid catalyst provided by this invention has a stable structure, good high temperature resistance, is non-toxic, does not deform or swell during the reaction, and is easy to recover after the reaction.

[0014] 2. The supported acidic catalyst provided by this invention has readily available raw materials, low preparation cost, simple preparation method, easy-to-control conditions, and good product repeatability.

[0015] 3. The supported acidic catalyst provided by this invention provides a mild process for oleic acid ester synthesis reactions, with low requirements for the reaction equipment. It also results in high oleic acid conversion and high selectivity for oleic acid esters.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0017] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0018] To achieve the above objectives, a first aspect of the present invention provides a supported acidic catalyst, the catalyst comprising a support and an active component supported on the support;

[0019] The support is a mesoporous carbon material, and the active component is lanthanum p-toluenesulfonate. Based on the total weight of the supported acidic catalyst, the content of the mesoporous carbon material is 25-55 wt%, preferably 31-49 wt%, more preferably 35-44 wt%, and the content of the lanthanum p-toluenesulfonate is 45-75 wt%, preferably 51-69 wt%, more preferably 56-65 wt%.

[0020] The inventors of this invention have discovered that, in the prior art, esterification catalysts used for the production of oleic acid esters are divided into two categories: homogeneous and heterogeneous. 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, but 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. Compared with homogeneous esterification catalysts, solid acid catalysts have significant advantages in catalyzing esterification reactions. Because these catalysts are in different phases from the reactants, post-reaction processing is simple, and they can be recovered and reused. Although solid esterification catalysts solve the problems of difficult product separation and severe equipment corrosion, they are rarely used in industrial production due to disadvantages such as 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, but the ester yield is relatively low in the oleic acid ester synthesis reaction, and their high-temperature resistance is also poor. Resins are organic polymer materials that easily swell in organic solvents and are easily deformed or even decomposed in high-temperature environments, which is the main reason for the poor temperature resistance of resin catalysts. Developing novel solid catalyst systems to compensate for the performance deficiencies of resin catalysts is a good way to solve the problem.

[0021] As a typical organic acid, p-benzenesulfonic acid is a good esterification catalyst. However, this type of catalyst is readily soluble in water and methanol, leading to equipment corrosion and difficulty in product separation when used in the esterification reaction of oleic acid and methanol. Conversely, lanthanum p-toluenesulfonate not only maintains good esterification catalytic performance but is also poorly soluble in water and organic solvents, making it an excellent heterogeneous esterification catalyst. However, lanthanum p-toluenesulfonate is not suitable for fixed-bed reactors due to its difficulty in molding. Therefore, by selecting an appropriate support to load lanthanum p-toluenesulfonate, a novel catalyst can be prepared for the synthesis of oleic acid esters. To address the structural defects of the resin catalyst itself and improve the catalytic performance of the esterification catalyst, it is essential to first select a material with excellent structural characteristics as the support. The selected support material should have a large specific surface area and pore volume to accommodate more active groups. High specific surface area mesoporous carbon materials are a new type of non-silicon-based mesoporous material with ultra-high specific surface area, huge pore volume, and large pore size. Compared with pure silicon mesoporous materials, mesoporous carbon materials exhibit special properties, with higher specific surface area and pore volume, simpler and easier synthesis, no physiological toxicity, and are more suitable for oleic acid esterification reactions.

[0022] The inventors of this invention discovered during the development of esterification catalysts that, by using an appropriate method to support lanthanum p-toluenesulfonate on a high specific surface area mesoporous carbon material, a supported acidic catalyst can be obtained for the esterification reaction of oleic acid. This supported acidic catalyst features high catalytic activity, simple preparation, and low dosage. Furthermore, this supported catalyst not only does not swell or deform in organic solvents but also exhibits good temperature resistance. The reacted supported acidic catalyst is insoluble in organic systems, easily separated from the product, and requires simple post-processing. It also has good reusability, making it an environmentally friendly catalyst with promising application prospects.

[0023] According to the present invention, preferably, the mesoporous carbon material is a high specific surface area mesoporous carbon material with a specific surface area of ​​2500-3500 m². 2 / g, preferably 2800-3000m 2 / g, pore volume 1.0-2.5cm³ 3 / g, preferably 2.0-2.5cm 3 / g, with an average pore size of 10-14nm, preferably 13-14nm.

[0024] In this invention, by using the aforementioned high specific surface area mesoporous carbon material, the high specific surface area and large pore volume of the mesoporous carbon material can be used to achieve uniform dispersion of the loaded active components.

[0025] According to the present invention, preferably, the specific surface area of ​​the supported acidic catalyst is 1100-2000 m². 2 / g, pore volume 1.2-1.5cm³3 / g, with an average pore size of 7-11nm.

[0026] A second aspect of the present invention provides a method for preparing the supported acidic catalyst, comprising the following steps:

[0027] (1) Mix mesoporous carbon material and lanthanum salt, and then ball mill them to obtain a catalyst intermediate;

[0028] (2) The catalyst intermediate is reacted with an aqueous solution of p-toluenesulfonic acid to obtain a solid product, which is then washed, dried and calcined to obtain the supported acid catalyst.

[0029] According to the present invention, preferably, in step (1), the lanthanum salt is at least one of lanthanum carbonate, lanthanum nitrate and lanthanum chloride.

[0030] According to the present invention, preferably, in step (1), the mixing weight ratio of the mesoporous carbon material and the lanthanum salt is 1:(0.5-4), more preferably 1:(1.0-2.5).

[0031] According to the present invention, preferably, in step (1), the conditions for ball milling include: a ball milling speed of 300-500 r / min, a temperature of 30-80℃, and a time of 2-10 hours.

[0032] According to the present invention, preferably, in step (2), the mass concentration of the p-toluenesulfonic acid aqueous solution is 2-20 wt%, more preferably 5-15 wt%.

[0033] According to the present invention, preferably, in step (2), the weight ratio of the catalyst intermediate to the aqueous p-toluenesulfonic acid solution is 1:(5-30), more preferably 1:(6-15).

[0034] According to the present invention, preferably, in step (2), the conditions for the contact reaction include: a temperature of 70-140°C, preferably 90-120°C, and a time of 2-10 h, preferably 3-8 h. Preferably, to achieve better mixing, rapid stirring or ultrasonic means can be used to improve reaction efficiency during the contact reaction between the catalyst intermediate and the p-toluenesulfonic acid aqueous solution.

[0035] According to the present invention, in step (2), the method for separating the solid product is not particularly required and 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 the funnel or using a centrifugal filter.

[0036] According to the present invention, the washing conditions in step (2) are not particularly limited. For example, the washing process may include: after filtration, the solid product is obtained, and the solid product is repeatedly washed with distilled water (the number of washing times may be 2-10), and then vacuum filtered.

[0037] According to the present invention, in step (2), the drying conditions include: a temperature of 80-150°C, preferably 100-130°C; and a time of 2-20 hours, preferably 3-12 hours.

[0038] According to the present invention, in step (2), the calcination conditions include: a temperature of 200-300℃, preferably 220-280℃; and a time of 1-10h, preferably 2-5h.

[0039] A third aspect of the invention provides the application of the supported acidic catalyst in the synthesis reaction of oleate esters.

[0040] According to the present invention, preferably, the oleate is methyl oleate.

[0041] A fourth aspect of the present invention provides a method for preparing an oleic acid ester, the method comprising: reacting oleic acid, a lower alcohol, and a catalyst.

[0042] In this invention, the conditions for the contact reaction include: a temperature of 40-100℃, preferably 50-80℃; a pressure of 0.01-5.0 MPa, preferably 0.1-3.0 MPa; a catalyst-oleic acid-lower alcohol weight ratio of 1:2-50:1-10, preferably 1:5-20:2-5; and a time of 1-12 h, preferably 2-8 h; wherein the lower alcohol is preferably a C1-C4 alcohol, more preferably methanol.

[0043] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0044] In the following examples and comparative examples:

[0045] 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.

[0046] 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.

[0047] The rotary evaporator was manufactured by IKA GmbH in Germany, and its model number is RV10 digital.

[0048] The drying oven was manufactured by Shanghai Yiheng Scientific Instruments Co., Ltd., model DHG-9030A.

[0049] The muffle furnace is manufactured by CARBOLITE, model CWF1100.

[0050] The high specific surface area mesoporous carbon material was purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.; the reagents used in the examples and comparative examples were all purchased from Sinopharm Chemical Reagent Co., Ltd., and the reagent purity was analytical grade.

[0051] Example 1

[0052] (1) Preparation of supported acid catalysts

[0053] At room temperature, 8.0 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 3 11.8 g of lanthanum carbonate octahydrate (with an average pore size of 14 nm) and 1 g of lanthanum carbonate octahydrate were mixed and transferred to a 100 ml ball mill jar. The ball mill jar was made of polytetrafluoroethylene, and the grinding balls were made of agate with a diameter of 3 mm. There were two grinding balls, and the rotation speed was 400 r / min. The ball mill jar was sealed and ball milled at 60 °C for 5 h to obtain catalyst intermediate A.

[0054] 10g of the above catalyst intermediate A was mixed with 80g of a 10% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 100℃ for 6h. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed 6 times with 200ml of distilled water, dried at 110℃ for 8h, and then calcined at 250℃ for 3h to obtain the supported acidic catalyst A.

[0055] The specific surface area of ​​supported acidic catalyst A is 1620 m². 2 / g, pore volume 1.4cm³ 3 / g, with an average pore size of 9.1nm.

[0056] Based on the total weight of the supported acidic catalyst A, the content of high specific surface area mesoporous carbon is 39.8% by weight, and the content of lanthanum p-toluenesulfonate is 60.2% by weight.

[0057] (2) Evaluation of catalyst reaction performance

[0058] One gram of supported acidic catalyst A was weighed, along with 40 grams of oleic acid and 10 grams of methanol, and placed together in a 100 ml three-necked flask. A condenser was added, and the mixture was stirred under reflux at 60 °C for 6 hours. After cooling to room temperature, the product was centrifuged and analyzed using an Agilent 7890A gas chromatograph equipped with an FFAP capillary column and a flame ionization detector (FID). Quantitative analysis was performed using programmed temperature ramping and correction factors. The oleic acid conversion rate was 99.2%, and the selectivity for methyl oleate was 99.8%.

[0059] Example 2

[0060] (1) Preparation of supported acid catalysts

[0061] At room temperature, 7.2 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 3 / g (with an average pore size of 14nm) and 12.7g of lanthanum carbonate octahydrate were mixed and transferred to a 100ml ball mill jar. The ball mill jar was made of polytetrafluoroethylene, and the grinding balls were made of agate with a diameter of 2mm, with 4 balls used. The rotation speed was 350r / min. The ball mill jar was sealed and ball milled at 70℃ for 3h. Catalyst intermediate B was obtained.

[0062] 10g of the above catalyst intermediate B was mixed with 70g of a 12% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 90°C for 8 hours. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed eight times with 150ml of distilled water, dried at 100°C for 12 hours, and then calcined at 230°C for 4 hours to obtain the supported acidic catalyst B.

[0063] The specific surface area of ​​supported acid catalyst B is 1487 m². 2 / g, pore volume 1.3cm³ 3 / g, with an average pore size of 8.4nm.

[0064] Based on the total weight of the supported acidic catalyst B, the content of high specific surface area mesoporous carbon is 35.9% by weight, and the content of lanthanum p-toluenesulfonate is 64.1% by weight.

[0065] (2) Evaluation of catalyst reaction performance

[0066] The esterification performance of catalyst B was tested according to step (2) in Example 1. The oleic acid conversion rate was 99.4%, and the selectivity for methyl oleate was 99.7%.

[0067] Example 3

[0068] (1) Preparation of supported acid catalysts

[0069] At room temperature, 8.8 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 3 11.0 g of lanthanum carbonate octahydrate (with an average pore size of 14 nm) and 1 g of lanthanum carbonate octahydrate were mixed and transferred to a 100 ml ball mill jar made of polytetrafluoroethylene (PTFE). Three agate grinding balls (2 mm in diameter) were used at a rotation speed of 450 r / min. The ball mill jar was sealed and milled at 50 °C for 8 h. Catalyst intermediate C was obtained.

[0070] 10g of the above catalyst intermediate C was mixed with 90g of an 8% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 120℃ for 3h. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 250ml of distilled water, dried at 130℃ for 3h, and then calcined at 260℃ for 3h to obtain the supported acidic catalyst C.

[0071] The specific surface area of ​​the supported acidic catalyst C is 1709 m². 2 / g, pore volume 1.5cm³ 3 / g, with an average pore size of 9.6nm.

[0072] Based on the total weight of the supported acidic catalyst C, the content of high specific surface area mesoporous carbon is 43.7% by weight, and the content of lanthanum p-toluenesulfonate is 56.3% by weight.

[0073] (2) Evaluation of catalyst reaction performance

[0074] The esterification performance of catalyst C was tested according to step (2) in Example 1. The oleic acid conversion rate was 99.0%, and the selectivity for methyl oleate was 99.6%.

[0075] Example 4

[0076] (1) Preparation of supported acid catalysts

[0077] At room temperature, 6.3 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 3 / g (with an average pore size of 14nm) and 13.5g of lanthanum carbonate octahydrate were mixed and transferred to a 100ml ball mill jar made of polytetrafluoroethylene. Two agate grinding balls, each 3mm in diameter, were used, and the milling speed was 400r / min. The ball mill jar was sealed and milled at 80℃ for 2 hours. Catalyst intermediate D was obtained.

[0078] 10g of the above catalyst intermediate D was mixed with 60g of a 15% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 100℃ for 7h. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed 8 times with 150ml of distilled water, dried at 110℃ for 8h, and then calcined at 220℃ for 5h to obtain the supported acidic catalyst D.

[0079] The specific surface area of ​​the supported acidic catalyst D is 1300 m². 2 / g, pore volume 1.2cm³ 3 / g, with an average pore size of 8.0nm.

[0080] Based on the total weight of the supported acidic catalyst D, the content of high specific surface area mesoporous carbon is 31.0 wt%, and the content of lanthanum p-toluenesulfonate is 69.0 wt%.

[0081] (2) Evaluation of catalyst reaction performance

[0082] The esterification performance of catalyst D was tested according to step (2) in Example 1. The oleic acid conversion rate was 98.7%, and the selectivity for methyl oleate was 99.3%.

[0083] Example 5

[0084] (1) Preparation of supported acid catalysts

[0085] At room temperature, 9.8 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 3 / g (with an average pore size of 14nm) and 10g of lanthanum carbonate octahydrate were mixed and transferred to a 100ml ball mill jar. The ball mill jar was made of polytetrafluoroethylene, and the grinding balls were made of agate with a diameter of 2mm, with 3 balls used. The rotation speed was 500r / min. The ball mill jar was sealed and ball milled at 40℃ for 8h. Catalyst intermediate E was obtained.

[0086] 10g of the above catalyst intermediate E was mixed with 130g of a 5% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 120°C for 3 hours. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed three times with 300ml of distilled water, dried at 130°C for 3 hours, and then calcined at 280°C for 2 hours to obtain the supported acidic catalyst E.

[0087] The specific surface area of ​​the supported acid catalyst E is 1800 m². 2 / g, pore volume 1.6cm³ 3 / g, with an average pore size of 10nm.

[0088] Based on the total weight of the supported acidic catalyst E, the content of high specific surface area mesoporous carbon is 49.0 wt%, and the content of lanthanum p-toluenesulfonate is 51.0 wt%.

[0089] (2) Evaluation of catalyst reaction performance

[0090] The esterification performance of catalyst E was tested according to step (2) in Example 1. The oleic acid conversion rate was 98.5%, and the selectivity for methyl oleate was 99.2%.

[0091] Example 6

[0092] (1) Preparation of supported acid catalysts

[0093] At room temperature, 5.0 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 3 14.5 g of lanthanum carbonate octahydrate (with an average pore size of 14 nm) and 1 g of lanthanum carbonate octahydrate were mixed and transferred to a 100 ml ball mill jar made of polytetrafluoroethylene (PTFE). Two agate grinding balls (3 mm in diameter) were used, and the milling speed was 400 rpm. The ball mill jar was sealed and milled at 50 °C for 4 hours. Catalyst intermediate F was obtained.

[0094] 10g of the above catalyst intermediate F was mixed with 50g of a 20% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 70°C for 10h. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed 10 times with 100ml of distilled water, dried at 80°C for 20h, and then calcined at 300°C for 1h to obtain the supported acidic catalyst F.

[0095] The specific surface area of ​​the supported acid catalyst F is 1100 m². 2 / g, pore volume 1.0cm³ 3 / g, with an average pore size of 7.0nm.

[0096] Based on the total weight of the supported acidic catalyst F, the content of high specific surface area mesoporous carbon is 25.0 wt%, and the content of lanthanum p-toluenesulfonate is 75.0 wt%.

[0097] (2) Evaluation of catalyst reaction performance

[0098] The esterification performance of catalyst F was tested according to step (2) in Example 1. The oleic acid conversion rate was 98.1%, and the selectivity for methyl oleate was 99.0%.

[0099] Example 7

[0100] (1) Preparation of supported acid catalysts

[0101] At room temperature, 11.0 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 3 / g (with an average pore size of 14nm) and 8.8g of lanthanum carbonate octahydrate were mixed and transferred to a 100ml ball mill jar made of polytetrafluoroethylene. Three agate grinding balls with a diameter of 2mm were used, and the milling speed was 500r / min. The ball mill jar was sealed and milled at 30℃ for 10h. Catalyst intermediate G was obtained.

[0102] 10 g of the above catalyst intermediate G was mixed with 300 g of a 2% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 140 °C for 2 h. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed twice with 400 ml of distilled water, dried at 150 °C for 2 h, and then calcined at 200 °C for 10 h to obtain the supported acidic catalyst G.

[0103] The specific surface area of ​​the supported acidic catalyst G is 2000 m². 2 / g, pore volume 1.8cm³ 3 / g, with an average pore size of 11nm.

[0104] Based on the total weight of the supported acidic catalyst G, the content of high specific surface area mesoporous carbon is 55.0 wt%, and the content of lanthanum p-toluenesulfonate is 45.0 wt%.

[0105] (2) Evaluation of catalyst reaction performance

[0106] The esterification performance of catalyst G was tested according to step (2) in Example 1. The oleic acid conversion rate was 98.0%, and the selectivity for methyl oleate was 98.8%.

[0107] Example 8

[0108] The supported acid catalyst H was prepared in the same manner as in Example 1, except that 11.8 g of lanthanum carbonate octahydrate in step (1) was replaced with 16.7 g of lanthanum nitrate.

[0109] The specific surface area of ​​supported acidic catalyst A is 1728 m². 2 / g, pore volume 1.5cm³ 3 / g, with an average pore size of 9.7nm.

[0110] Based on the total weight of the supported acidic catalyst A, the content of high specific surface area mesoporous carbon is 44.0 wt%, and the content of lanthanum p-toluenesulfonate is 56.0 wt%.

[0111] The catalytic performance of the supported acidic catalyst H was tested according to the esterification reaction performance evaluation method in step (2) of Example 1. The oleic acid conversion rate was 98.9%, and the selectivity for methyl oleate was 99.5%.

[0112] Comparative Example 1

[0113] (1) Preparation of supported acid catalysts

[0114] At room temperature, 3.0 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 3 16.7 g of lanthanum carbonate octahydrate (with an average pore size of 14 nm) and 1 g of lanthanum carbonate octahydrate were mixed and transferred to a 100 ml ball mill jar made of polytetrafluoroethylene (PTFE). Four agate grinding balls (2 mm in diameter) were used at a rotation speed of 300 rpm. The ball mill jar was sealed and milled at 80 °C for 2 hours to obtain catalyst intermediate D1.

[0115] 10g of the above catalyst intermediate D1 was mixed with 40g of a 28% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 70°C for 10h. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed 6 times with 100ml of distilled water, dried at 110°C for 10h, and then calcined at 320°C for 1h to obtain the supported acidic catalyst D1.

[0116] The supported acidic catalyst D1 has a specific surface area of ​​980 m². 2 / g, pore volume 0.8cm³ 3 / g, with an average pore size of 6.0nm.

[0117] Based on the total weight of the supported acidic catalyst D1, the content of high specific surface area mesoporous carbon is 15.0 wt%, and the content of lanthanum p-toluenesulfonate is 85.0 wt%.

[0118] (2) Evaluation of catalyst reaction performance

[0119] The catalytic performance of catalyst D1 was tested according to the esterification reaction performance evaluation method in step (2) of Example 1. The oleic acid conversion rate was 90.1%, and the selectivity for methyl oleate was 95.4%.

[0120] Comparative Example 2

[0121] (1) Preparation of supported acid catalysts

[0122] At room temperature, 16.0 g of high specific surface area mesoporous carbon (specific surface area of ​​3000 m²) was... 2 / g, pore volume 2.0cm³ 33.9 g of lanthanum carbonate octahydrate (with an average pore size of 14 nm) and 4 g of lanthanum carbonate octahydrate were mixed and transferred to a 100 ml ball mill jar made of polytetrafluoroethylene (PTFE). Three agate grinding balls (2 mm in diameter) were used at a rotation speed of 500 rpm. The ball mill jar was sealed and milled at 30 °C for 10 h. Catalyst intermediate D2 was obtained.

[0123] 10 g of the above catalyst intermediate D2 was mixed with 500 g of a 0.5% aqueous solution of p-toluenesulfonic acid, and the mixture was stirred at 140 °C for 2 h. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed twice with 400 ml of distilled water, dried at 150 °C for 2 h, and then calcined at 200 °C for 10 h to obtain the supported acidic catalyst D2.

[0124] The specific surface area of ​​the supported acidic catalyst D2 is 2200 m². 2 / g, pore volume 2.0cm³ 3 / g, with an average pore size of 12nm.

[0125] Based on the total weight of the supported acidic catalyst D2, the content of high specific surface area mesoporous carbon is 80.0% by weight, and the content of lanthanum p-toluenesulfonate is 20.0% by weight.

[0126] (2) Evaluation of catalyst reaction performance

[0127] The catalytic performance of catalyst D2 was tested according to the esterification reaction performance evaluation method in step (2) of Example 1. The oleic acid conversion rate was 87.2%, and the selectivity for methyl oleate was 95.9%.

[0128] Comparative Example 3

[0129] The supported acid catalyst D3 was prepared using the same method as in Example 1, except that the high specific surface area mesoporous carbon in step (1) was replaced with commercially available silica (purchased from Qingdao Hailang Silica Gel Desiccant Factory, specific surface area 329 m²). 2 / g).

[0130] The catalytic performance of catalyst D3 was tested according to the esterification reaction performance evaluation method in step (2) of Example 1. The oleic acid conversion rate was 81.9%, and the selectivity for methyl oleate was 94.7%.

[0131] Comparative Example 4

[0132] Following step (2) in Example 1, the ketalization performance was tested using high-specific-surface-area mesoporous carbon without lanthanum p-toluenesulfonate as catalyst D4. The oleic acid conversion rate was 2.5%, and the selectivity for methyl oleate was 82.1%.

[0133] Comparative Example 5

[0134] The supported acid catalyst was prepared using the same method as step (1) in Example 1, except that: "high specific surface area mesoporous carbon (specific surface area of ​​3000 m²)" was used. 2 / g, pore volume 2.0cm³ 3 Replace " / g, average pore size is 14nm)" with "conventional mesoporous carbon material (specific surface area is 1500m²)". 2 / g, pore volume 1.2cm³ 3 / g, with an average pore size of 16nm. ), thus obtaining the supported acidic catalyst D5.

[0135] The specific surface area of ​​the supported acidic catalyst D5 was found to be 515 m². 2 / g, pore volume 0.5cm³ 3 / g, with an average pore size of 8.0nm.

[0136] The catalytic performance of catalyst D5 was tested according to the esterification reaction performance evaluation method in step (2) of Example 1. The oleic acid conversion rate was 91.8%, and the selectivity for methyl oleate was 96.0%.

[0137] Comparative Example 6

[0138] (1) Preparation of supported acid catalysts

[0139] 4.1g of high specific surface area mesoporous carbon (specific surface area of ​​3000m²) was added. 2 / g, pore volume 2.0cm³ 3 A mixture of 5.9 g of lanthanum carbonate octahydrate (with an average pore size of 14 nm) and 80 g of a 10% aqueous solution of p-toluenesulfonic acid was stirred at 100 °C for 6 h. After the reaction, the mixture was cooled to room temperature and filtered to obtain a solid product. The solid product was washed six times with 200 ml of distilled water, dried at 110 °C for 8 h, and then calcined at 250 °C for 3 h to obtain the supported acidic catalyst D6.

[0140] The specific surface area of ​​the supported acidic catalyst D6 is 2034 m². 2 / g, pore volume 1.8cm³ 3 / g, with an average pore size of 11.5nm.

[0141] Based on the total weight of the supported acidic catalyst A, the content of high specific surface area mesoporous carbon is 77.0 wt%, and the content of lanthanum p-toluenesulfonate is 23.0 wt%.

[0142] The catalytic performance of catalyst D6 was tested according to the esterification reaction performance evaluation method in step (2) of Example 1. The oleic acid conversion rate was 87.9%, and the selectivity for methyl oleate was 96.2%.

[0143] The results above show that the supported acidic catalyst provided by the present invention can directly convert oleic acid and methanol into methyl oleate, resulting in a high oleic acid conversion rate and methyl oleate selectivity.

[0144] In Comparative Example 1, the excessively high lanthanum p-toluenesulfonate content on the supported acidic catalyst caused the active components to aggregate on the catalyst surface and disperse unevenly on the support. This resulted in some active centers being unable to effectively exert their catalytic effect during the reaction, leading to a low oleic acid conversion rate and low selectivity for methyl oleate.

[0145] In Comparative Example 2, the low content of lanthanum p-toluenesulfonate on the supported acidic catalyst and the insufficient active sites during the reaction resulted in a low conversion rate of methacrylic acid and a low selectivity for methyl methacrylate.

[0146] In Comparative Example 3, instead of using the high specific surface area mesoporous carbon material specifically defined in this invention as the catalyst support, commercially available silica was used. Because the pore structure of commercially available silica differs significantly from that of the high specific surface area mesoporous carbon material, the pore volume is smaller. This uneven dispersion of the active component on the surface of the commercially available silica resulted in a lower oleic acid conversion rate and lower selectivity for methyl oleate.

[0147] In Comparative Example 4, the esterification reaction of oleic acid was catalyzed by a high specific surface area mesoporous carbon material without active component loading. Since the surface of the high specific surface area mesoporous carbon material is almost free of acidic centers, it cannot effectively catalyze the esterification reaction, resulting in extremely low oleic acid conversion and extremely low selectivity of methyl oleate.

[0148] In Comparative Example 5, replacing the high specific surface area mesoporous carbon material with a conventional mesoporous carbon material significantly reduced the catalyst's performance. This is because the specific surface area and pore volume of the conventional mesoporous carbon material are significantly smaller than those of the ultra-high specific surface area mesoporous carbon material, which is not conducive to the immobilization of the active component, resulting in a lower oleic acid conversion rate and lower selectivity for methyl oleate.

[0149] In Comparative Example 6, instead of a two-step method to support lanthanum p-toluenesulfonate on a high specific surface area mesoporous carbon material, a one-step reaction was used to prepare the catalyst from p-toluenesulfonic acid, a lanthanum-containing inorganic salt, and the high specific surface area mesoporous carbon material. In solution, p-toluenesulfonic acid may react directly with the lanthanum-containing inorganic salt to form lanthanum p-toluenesulfonate. However, the generated lanthanum p-toluenesulfonate may not necessarily be supported on the high specific surface area mesoporous carbon material; it may also remain in solution. This results in an excessively low lanthanum p-toluenesulfonate content on the supported acidic catalyst, leading to insufficient active sites during the reaction, resulting in a low conversion rate of methacrylic acid and low selectivity for methyl methacrylate.

[0150] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0151] 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.

Claims

1. A supported acidic catalyst, characterized in that, The catalyst includes a support and an active component supported on the support; The support is a mesoporous carbon material, and the active component is lanthanum p-toluenesulfonate. Based on the total weight of the supported acidic catalyst, the content of the mesoporous carbon material is 25-55 wt%, preferably 31-49 wt%, more preferably 35-44 wt%, and the content of the lanthanum p-toluenesulfonate is 45-75 wt%, preferably 51-69 wt%, more preferably 56-65 wt%.

2. The supported acidic catalyst according to claim 1, wherein, The mesoporous carbon material is a high specific surface area mesoporous carbon material with a specific surface area of ​​2500-3500 m². 2 / g, preferably 2800-3000m 2 / g, pore volume 1.0-2.5cm³ 3 / g, preferably 2.0-2.5cm 3 / g, with an average pore size of 10-14nm, preferably 13-14nm.

3. The supported acidic catalyst according to claim 1, wherein, The specific surface area of ​​the supported acidic catalyst is 1100-2000 m². 2 / g, pore volume 1.2-1.5cm³ 3 / g, with an average pore size of 7-11nm.

4. The method for preparing the supported acidic catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix mesoporous carbon material and lanthanum salt, and then ball mill them to obtain a catalyst intermediate; (2) The catalyst intermediate is reacted with an aqueous solution of p-toluenesulfonic acid to obtain a solid product, which is then washed, dried and calcined to obtain the supported acid catalyst.

5. The preparation method according to claim 4, wherein, In step (1), the lanthanum salt is at least one of lanthanum carbonate, lanthanum nitrate and lanthanum chloride.

6. The preparation method according to claim 4, wherein, In step (1), the mixing weight ratio of the mesoporous carbon material and the lanthanum salt is 1:(0.5-4), preferably 1:(1.0-2.5).

7. The preparation method according to claim 4, wherein, In step (1), the conditions for ball milling include: a ball milling speed of 300-500 r / min, a temperature of 30-80℃, and a time of 2-10 hours.

8. The preparation method according to claim 4, wherein, In step (2), the mass concentration of the p-toluenesulfonic acid aqueous solution is 2-20 wt%, preferably 5-15 wt%.

9. The preparation method according to claim 4, wherein, In step (2), the weight ratio of the catalyst intermediate to the p-toluenesulfonic acid aqueous solution is 1:(5-30), preferably 1:(6-15).

10. The preparation method according to claim 4, wherein, In step (2), the conditions for the contact reaction include: a temperature of 70-140℃, preferably 90-120℃, and a time of 2-10h, preferably 3-8h.

11. The preparation method according to claim 4, wherein, In step (2), the filtration is at least one of gravity filtration, pressure filtration, vacuum filtration and centrifugal filtration; The drying conditions include: a temperature of 80-150℃, preferably 100-130℃; and a time of 2-20 hours, preferably 3-12 hours. The roasting conditions include: a temperature of 200-300℃, preferably 220-280℃; and a time of 1-10h, preferably 2-5h.

12. The application of the supported acidic catalyst according to any one of claims 1-3 in the synthesis reaction of oleate esters; preferably, the oleate ester is methyl oleate.

13. A method for preparing an oleate, characterized in that, The method includes: reacting oleic acid, lower alcohols, and a catalyst. Preferably, the conditions for the contact reaction include: a temperature of 40-100℃, preferably 50-80℃; a pressure of 0.01-5.0 MPa, preferably 0.1-3.0 MPa; a catalyst-oleic acid-lower alcohol weight ratio of 1:2-50:1-10, preferably 1:5-20:2-5; and a time of 1-12 h, preferably 2-8 h; wherein the lower alcohol is preferably a C1-C4 alcohol, more preferably methanol.