Modified super-macroporous silica gel catalyst, preparation method thereof and application of modified super-macroporous silica gel catalyst in methyl oleate synthesis reaction

Abstract

The invention relates to the field of fine chemical engineering, and discloses a modified super-macroporous silica gel catalyst, a preparation method thereof and application of the modified super-macroporous silica gel catalyst in methyl oleate synthesis reaction. The modified super-macroporous silica gel catalyst is obtained by sulfonating super-macroporous silica gel, and the surface sulfonic acid group of the modified super-macroporous silica gel catalyst is 1-3 mmol / g. When the modified super-macroporous silica gel catalyst is used for a synthetic reaction of methyl oleate, higher oleic acid conversion rate and methyl oleate selectivity can be obtained.

Description

Technical Field

[0001] The invention relates to the field of fine chemicals, and in particular to a modified ultra-macroporous silica catalyst and a preparation method thereof, as well as an application of the catalyst in a methyl oleate synthesis reaction. Background Art

[0002] Methyl oleate is an important organic chemical product, mainly used as surfactant base raw material, leather and rubber softener, oil exploration non-fluorescent mud lubricant, plasticizer, water repellent, resin toughening agent, and is also commonly used in organic synthesis. In addition, methyl oleate can also be used as an intermediate of detergent, emulsifier, wetting agent and stabilizer, widely used in various emulsified products, and also used as a solvent for perfumes and a lubricant for spray products. At present, the traditional process of industrial production of methyl oleate is to use inorganic acid or organic acid (for example: concentrated sulfuric acid, concentrated hydrochloric acid or p-toluenesulfonic acid) as catalyst to catalyze oleic acid and methanol to generate methyl oleate by esterification. Inorganic acid or organic acid catalyst has the advantage of low price, but there are disadvantages such as serious environmental pollution, high requirements on equipment material, many side reactions, many by-products, and difficult separation and purification of the obtained products. In recent years, the production process of oleic acid esters in my country has been continuously developed, and the production capacity of oleic acid esters has been continuously improved. The use of solid acid or cation exchange resin as a catalyst for the synthesis reaction of methyl oleate has been greatly developed and has also been widely used in industrial production. Solid catalysts show advantages such as good stability, high selectivity, low cost, and easy separation in esterification reactions. However, this type of catalyst has a slow reaction rate and a low ester yield. Cation exchange resins show advantages such as good stability, high selectivity, low cost, and easy separation in esterification reactions. However, the cation exchange resin itself has poor heat resistance (generally suitable for esterification reactions at temperatures below 150°C), small specific surface area and pore volume, and the cation exchange resin is easy to swell. As a modified ultra-large pore silica gel catalyst, the reaction activity is poor and the ester yield is low.

[0003] Compared with resin catalysts, hydrogen-type zeolite molecular sieves have certain pore structures and surface acidity, which are suitable for catalyzing the esterification reaction of small molecules. However, the pore size of zeolite molecular sieves is small (0.5-0.7nm), which may inhibit the diffusion of large molecular products during the reaction; and the number of acid sites on the surface of zeolite molecular sieves is small, and the efficiency of catalytic esterification reactions is low. With the increasing demand for oleic acid esters, the prospect of synthesizing oleic acid esters by green and environmentally friendly processes is broad. For researchers, developing excellent performance catalysts for oleic acid ester synthesis reactions, improving reaction efficiency, and inhibiting the formation of by-products are important future work directions. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of excessive side reactions and serious environmental pollution of homogeneous acid catalysts used in the methyl oleate production process in the prior art, as well as the problems of poor catalytic activity and low ester selectivity of solid acid catalysts and acidic cation exchange resin catalysts. A modified ultra-macroporous silica gel catalyst and a preparation method thereof and application in a methyl oleate synthesis reaction are provided. The modified ultra-macroporous silica gel catalyst is used in a methyl oleate synthesis reaction to obtain a higher oleic acid conversion rate and methyl oleate selectivity.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a modified ultra-macroporous silica gel catalyst, wherein the modified ultra-macroporous silica gel catalyst is obtained by sulfonating ultra-macroporous silica gel, and the surface sulfonic acid group of the modified ultra-macroporous silica gel catalyst is 1-3 mmol / g.

[0006] The second aspect of the present invention provides a method for preparing a modified ultra-macroporous silica gel catalyst, wherein the preparation method comprises: contacting the ultra-macroporous silica gel with a halosulfonic acid for sulfonation treatment to obtain a modified ultra-macroporous silica gel catalyst;

[0007] Wherein, the weight ratio of the ultra-large pore silica gel to the halosulfonic acid is 1:(0.3-1.2).

[0008] The third aspect of the present invention provides a modified ultra-macroporous silica catalyst prepared by the aforementioned preparation method.

[0009] A fourth aspect of the present invention provides an application of the aforementioned modified ultra-macroporous silica catalyst in the synthesis reaction of methyl oleate.

[0010] Through the above technical solution, the technical solution of the present invention has the following advantages:

[0011] (1) The modified ultra-macroporous silica gel catalyst provided by the present 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.

[0012] (2) The raw materials of the modified ultra-large-porous silica catalyst provided by the present invention are easily available, the preparation cost is low, the preparation method is simple, the conditions are easy to control, and the product has good reproducibility.

[0013] (3) When the modified ultra-macroporous silica gel catalyst provided by the present invention is used for the synthesis reaction of oleic acid ester, the process conditions are mild and the requirements for the reaction device are not high. The oleic acid conversion rate is high and the oleic acid ester selectivity is high.

[0014] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1is a SEM scanning electron microscope image of the microscopic morphology of the ultra-macroporous silica gel A prepared in Example 1;

[0016] Figure 2 is the pore size distribution diagram of the ultra-large pore silica gel A prepared in Example 1;

[0017] Figure 3 This is the pore size distribution diagram of the modified ultra-macroporous silica catalyst A prepared in Example 1. DETAILED DESCRIPTION

[0018] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0019] As mentioned above, the first aspect of the present invention provides a modified ultra-macroporous silica catalyst, wherein the modified ultra-macroporous silica catalyst is obtained by sulfonating ultra-macroporous silica, and the surface sulfonic acid group of the modified ultra-macroporous silica catalyst is 1-3 mmol / g.

[0020] The inventors of the present invention have found that in the prior art, the esterification catalysts used to produce methyl oleate are divided into two categories: homogeneous and heterogeneous. Among them, homogeneous catalysts mainly include inorganic acid solutions and organic acids, and heterogeneous catalysts mainly include solid acids and cation exchange resins. The advantages of homogeneous catalysts are low price and good catalytic activity, but they are gradually eliminated due to defects such as difficulty in separating products from catalysts, more side reactions, and easy corrosion of equipment. Compared with homogeneous esterification catalysts, solid acid catalysts have great advantages in catalyzing esterification reactions. Since this type of catalyst is in different phases from the reactants, the post-reaction treatment is simple and can be recovered and reused. Although solid acid esterification catalysts solve the problems of difficult product separation and serious equipment corrosion, they are rarely used in industrial production due to the disadvantages of poor catalytic activity, high reaction temperature, and low product selectivity. Compared with the above catalysts, resin catalysts have the advantages of high selectivity, low cost, and easy separation, but the ester yield is low during the methyl oleate synthesis reaction, and the high temperature resistance is also poor. Resin is an organic polymer material that is easy to swell in organic solvents and deform or even decompose in high temperature environments. This is the main reason why resin catalysts have poor temperature resistance. Developing a new solid catalyst system to make up for the performance defects of resin catalysts is a good way to solve the problem.

[0021] In recent years, acidic zeolite molecular sieve catalysts have attracted extensive attention from researchers due to their stable structure and the advantages of active centers not easy to lose, and are often used as catalysts for esterification reactions. However, the pore size of zeolite molecular sieves is in the micropore range and the pore size is small. If the reactant molecules, intermediates or target product molecules involved in the reaction are large in size, catalysts with smaller pore sizes are not conducive to diffusion, which leads to a decrease in catalytic performance. Therefore, according to the specific circumstances of the esterification reaction, catalysts with larger pore sizes should be selected when larger molecules are involved in the reaction. Compared with zeolite molecular sieves, the pores of mesoporous materials are more suitable for the esterification reaction of oleic acid. Ultra-large pore silica gel has the structural characteristics of large pore size and large pore volume, which is suitable for esterification reaction of oleic acid. However, the surface acidity of silica gel material itself is weak, and the catalytic performance in esterification reaction is poor. If the above problems are to be solved, it is necessary to increase the number and strength of acid centers on the surface of ultra-large pore silica gel.

[0022] The inventors of the present invention found in the process of developing esterification catalysts that if ultra-large pore silica gel is sulfonated, the resulting modified ultra-large pore silica gel catalyst can be used for the esterification reaction of oleic acid. The modified ultra-large pore silica gel catalyst has the characteristics of high catalytic activity, simple preparation, and small dosage, and this catalyst belongs to an inorganic structure, not only will not swell and deform in organic solvents, but also has good temperature resistance. The modified ultra-large pore silica gel catalyst after the reaction is insoluble in organic systems, is easy to separate from the product, is simple to post-process, has good reusability, is an environmentally friendly catalyst, and has good application prospects.

[0023] According to the present invention, preferably, the surface sulfonic acid groups of the modified ultramacroporous silica catalyst are 1.5-2.5 mmol / g, more preferably 1.8-2.2 mmol / g.

[0024] According to the present invention, the ultra-large pore silica gel is a silica gel molecular sieve with a silicon dioxide content of 100%.

[0025] According to the present invention, the average particle diameter of the ultra-large pore silica gel is 20-60 μm, and the specific surface area is 150-600 m 2 / g, pore volume of 1-2.5mL / g, pore size of bimodal distribution, and the two peaks correspond to the first most probable pore size of 1-4.5nm and the second most probable pore size of 20-50nm; preferably, the average particle diameter of the ultra-large pore silica gel is 30-50μm, and the specific surface area is 250-500m 2 / g, pore volume is 1.4-2.0mL / g, pore size is bimodal, and the two peaks correspond to the first most probable pore size of 2.5-4nm and the second most probable pore size of 30-40nm. Under this condition, it is more conducive to the diffusion of raw material molecules and product molecules in the reaction, and the activity and selectivity of the esterification catalyst can be effectively improved.

[0026] According to the present invention, the method for preparing the ultra-macroporous silica gel comprises:

[0027] (1) in the presence of butanol and propylene glycol, contacting and mixing an inorganic silicon source with an acid agent, and filtering and washing the obtained mixture to obtain a silica gel filter cake;

[0028] (2) ball milling and spray drying the silica gel filter cake to obtain ultra-large pore silica gel.

[0029] According to the present invention, in step (1), the butanol is preferably n-butanol.

[0030] According to the present invention, in step (1), the inorganic silicon source can be one or more of water glass, sodium metasilicate, and silica sol; preferably water glass.

[0031] According to the present invention, in step (1), the acid agent can be any conventional substance or mixture (such as a solution) that can be used to adjust the pH value. Preferably, the inorganic acid solution is at least one aqueous solution selected from hydrochloric acid, sulfuric acid, nitric acid and hydrobromic acid. More preferably, the acid agent is an aqueous sulfuric acid solution.

[0032] According to the present invention, in step (1), the weight ratio of the inorganic silicon source, acid agent, butanol and glycerol can be 1: (0.05-0.5): (0.02-0.6): (0.02-0.6), preferably 1: (0.1-0.3): (0.06-0.4): (0.06-0.4).

[0033] According to the present invention, in step (1), the pH value of the mixture may be 1.5-4.5, preferably 2-4.

[0034] According to the present invention, in step (1), the preferred conditions for contacting the inorganic silicon source with the acid agent may include: a temperature of 15-40° C. and a time of 1.0-3.0 hours. In order to facilitate uniform mixing of the various substances, according to a preferred embodiment of the present invention, the mixing contact is carried out under stirring conditions.

[0035] According to the present invention, in step (1), the washing conditions are not particularly limited. For example, the washing process may include: obtaining a solid product after filtration, repeatedly washing the solid product with distilled water (the number of washing times may be 2-10) and then filtering with suction.

[0036] According to the present invention, in step (2), the ball milling conditions may include: the rotation speed of the grinding balls may be 300-500 r / min, the temperature in the ball milling jar may be 30-80° C., and the ball milling time may be 2-10 hours.

[0037] According to the present invention, in step (2), the spray drying conditions may include: a temperature of 100-300°C, and a rotation speed of 10000-15000 r / min; preferably, the spray drying conditions include: a temperature of 150-250°C, and a rotation speed of 11000-13000 r / min.

[0038] According to the present invention, the specific surface area of ​​the modified ultra-macroporous silica catalyst is 100-500m 2 / g, the pore volume is 0.6-1.8mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 0.8-4nm and the second most probable pore size of 15-45nm; preferably, the specific surface area of ​​the modified ultra-macroporous silica catalyst is 200-400m 2 / g, the pore volume is 1-1.6mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 1.8-3nm and the second most probable pore size of 25-35nm.

[0039] The second aspect of the present invention provides a method for preparing a modified ultra-macroporous silica gel catalyst, wherein the preparation method comprises: contacting the ultra-macroporous silica gel with a halosulfonic acid for sulfonation treatment to obtain a modified ultra-macroporous silica gel catalyst;

[0040] Wherein, the weight ratio of the ultra-large pore silica gel to the halosulfonic acid is 1:(0.3-1.2).

[0041] According to the present invention, preferably, the weight ratio of the ultra-large pore silica gel to the halosulfonic acid is 1:(0.5-0.9).

[0042] According to the present invention, the halosulfonic acid is selected from one or more of fluorosulfonic acid, chlorosulfonic acid, bromosulfonic acid and iodosulfonic acid, preferably chlorosulfonic acid; in the present invention, the advantage of using halosulfonic acid is that the halosulfonic acid can be riveted to the surface of the silica gel material in the form of chemical bonds during the modification process, the properties are relatively stable, and the utilization rate of the active groups of the catalyst is high.

[0043] According to the present invention, the average particle diameter of the ultra-large pore silica gel is 20-60 μm, and the specific surface area is 150-600 m 2 / g, pore volume of 1-2.5mL / g, pore size of bimodal distribution, and the two peaks correspond to the first most probable pore size of 1-4.5nm and the second most probable pore size of 20-50nm; preferably, the average particle diameter of the ultra-large pore silica gel is 30-50μm, and the specific surface area is 250-500m 2 / g, the pore volume is 1.4-2mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 2.5-4nm and the second most probable pore size of 30-40nm.

[0044] According to the present invention, in the method for preparing the modified ultra-macroporous silica gel catalyst, the method for preparing the ultra-macroporous silica gel is the same as described above and will not be repeated herein.

[0045] According to the present invention, ultra-large pore silica gel is contacted with halosulfonic acid for sulfonation treatment, and the gas generated in the reaction is absorbed by an alkaline aqueous solution; preferably, the alkaline aqueous solution can be a NaOH aqueous solution, a KOH aqueous solution, a NaHCO3 aqueous solution or a Na2CO3 aqueous solution, preferably a NaOH aqueous solution or a KOH aqueous solution.

[0046] According to the present invention, the conditions of the contact reaction include: the reaction temperature can be 0-40°C, preferably 10-30°C; the reaction time can be 0.2-8 hours, preferably 0.5-4 hours. Preferably, in order to achieve better reaction effect, the ultra-large pore silica gel can be quickly stirred during the contact reaction with the halosulfonic acid to improve the reaction efficiency.

[0047] The third aspect of the present invention provides a modified ultra-macroporous silica catalyst prepared by the aforementioned preparation method.

[0048] The fourth aspect of the present invention provides an application of the aforementioned modified ultra-macroporous silica catalyst in the synthesis reaction of methyl oleate.

[0049] According to the present invention, the application comprises: contacting the modified ultra-macroporous silica catalyst, oleic acid and methanol to react.

[0050] According to the present invention, the contact conditions of the oleic acid and methanol with the catalyst include: the contact temperature can be 40-100° C., preferably 50-80° C.; the reaction time can be 1-12 hours, preferably 2-8 hours.

[0051] According to the present invention, the weight ratio of the catalyst-modified ultra-large-porous silica gel, the oleic acid and the methanol is 1:(2-50):(1-10), preferably 1:(5-20):(2-5).

[0052] The present invention will be described in detail below through examples.

[0053] In the following examples and comparative examples:

[0054] (1) The pore structure parameter analysis of the samples was carried out on an ASAP2020-M+C adsorption instrument purchased from Micromeritics, USA. The samples were vacuum degassed at 350°C for 4 hours before measurement. The specific surface area of ​​the samples was calculated using the BET method, and the pore volume was calculated using the BJH model.

[0055] (2) The SEM images of the samples were obtained using an XL-30 field emission environmental scanning electron microscope produced by FEI Company, USA.

[0056] (3) The elemental analysis of the samples was carried out on an Eagle III energy dispersive X-ray fluorescence spectrometer produced by EDAX, USA. The density of sulfonic acid groups on the catalyst surface was calculated by the S content on the modified ultra-macroporous silica catalyst.

[0057] (4) The rotary evaporator was manufactured by IKA, Germany, model RV10 digital.

[0058] (5) The drying oven was manufactured by Shanghai Yiheng Scientific Instrument Co., Ltd., model DHG-9030A.

[0059] (6) The muffle furnace is manufactured by CARBOLITE, model CWF1100.

[0060] (7) The reagents used in the examples and comparative examples were purchased from Sinopharm Chemical Reagent Co., Ltd. and were of analytical purity.

[0061] Example 1

[0062] (1) Preparation of ultra-macroporous silica gel

[0063] 50 g of 15 wt% water glass, 10 g of 12 wt% sulfuric acid solution, 10 g of n-butanol and 10 g of glycerol were mixed at 20°C and the pH value was adjusted to 3 with 98 wt% sulfuric acid, and the contact reaction was carried out for 1.5 hours. The solid matter obtained by filtration was then washed 8 times with distilled water to obtain a silica gel filter cake.

[0064] 10g of the silica gel filter cake prepared above was placed in a 100mL ball mill, wherein the ball mill was made of polytetrafluoroethylene, the grinding ball was made of agate, the diameter of the grinding ball was 3mm, the number was 1, and the rotation speed was 400r / min. The ball mill was sealed and ball milled for 5h at a temperature of 60°C in the ball mill. The ball milled silica gel filter cake was spray dried at 200°C and a rotation speed of 12000r / min to obtain ultra-large pore silica gel A.

[0065] Figure 1 This is a SEM scanning electron microscope image of the microstructure of super-macroporous silica gel A. Figure 1It can be seen that the microscopic morphology of the ultra-macroporous silica gel A is spherical particles with an average particle size of 30-50 μm.

[0066] Figure 2 is the average pore size distribution diagram of super-large pore silica gel A, from Figure 2 It can be seen that the pore size of the material presents a bimodal distribution, with the first most probable pore size being 3.1 nm and the second most probable pore size being 33 nm.

[0067] The specific surface area of ​​super-large pore silica gel A is 347 m 2 / g, pore volume 1.6cm 3 / g.

[0068] (2) Preparation of modified ultra-macroporous silica catalyst

[0069] At room temperature of 50°C, add 12 grams of the above-mentioned ultra-large pore silica gel to a three-necked flask equipped with a constant pressure funnel and an exhaust gas outlet pipe, and install a mechanical stirring device. Add 8.5 grams of chlorosulfonic acid to the constant pressure funnel, and connect the exhaust gas outlet pipe to the NaOH aqueous solution. Under stirring conditions, add chlorosulfonic acid dropwise to the three-necked flask, and the acidic gas generated during the reaction is absorbed by the NaOH aqueous solution. After all the chlorosulfonic acid has been added, continue stirring for 1 hour. Take out the white solid in the three-necked flask, which is the modified ultra-large pore silica gel catalyst A.

[0070] Figure 3 is the average pore size distribution diagram of the modified ultra-macroporous silica catalyst A prepared in Example 1. Figure 3 It can be seen that the pore size of the catalyst presents a bimodal distribution, with the first most probable pore size being 2.5 nm and the second most probable pore size being 28 nm.

[0071] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst A is 284 m 2 / g, and the pore volume is 1.4mL / g.

[0072] In addition, the surface sulfonic acid groups of the modified ultra-macroporous silica catalyst A are 2.1 mmol / g.

[0073] (3) Catalyst reaction performance evaluation

[0074] Weigh 1 gram of modified ultra-large-porous silica catalyst A, weigh 30 grams of oleic acid and 6.8 grams of methanol, put them into a 100 ml three-necked flask, add a condenser, stir under reflux at 60°C for 6 hours, cool to room temperature, centrifuge the product and analyze it with an Agilent 7890A gas chromatograph equipped with a FFAP capillary column and a hydrogen flame detector (FID), using programmed temperature and correction factors for quantitative analysis. The oleic acid conversion rate is 98.5%, and the selectivity of methyl oleate is 99.6%.

[0075] Example 2

[0076] (1) Preparation of ultra-macroporous silica gel

[0077] 50 g of 15 wt% water glass, 15 g of 12 wt% sulfuric acid solution, 3 g of n-butanol and 20 g of glycerol were mixed at 15°C and the pH value was adjusted to 2 with 98 wt% sulfuric acid, and the reaction was carried out for 2.5 hours. The solid matter obtained by filtration was then washed 10 times with distilled water to obtain a silica gel filter cake.

[0078] 10g of the silica gel filter cake prepared above was placed in a 100mL ball mill, wherein the ball mill was made of polytetrafluoroethylene, the grinding balls were made of agate, the diameter of the grinding balls was 2mm, the number was 4, and the rotation speed was 300r / min. The ball mill was closed and ball milled for 2h at a temperature of 80°C in the ball mill. The ball-milled silica gel filter cake was spray dried at 250°C and a rotation speed of 11000r / min to obtain ultra-large pore silica gel B.

[0079] The specific surface area of ​​super-macroporous silica gel B is 372 m 2 / g, pore volume 1.8cm 3 / g, the first most probable pore size is 3.4nm, and the second most probable pore size is 35nm.

[0080] (2) Preparation of modified ultra-macroporous silica catalyst

[0081] At room temperature, add 12 grams of the above-mentioned ultra-large pore silica gel to a three-necked flask equipped with a constant pressure funnel and an exhaust gas outlet pipe, and install a mechanical stirring device. Add 6.0 grams of chlorosulfonic acid to the constant pressure funnel, and connect the exhaust gas outlet pipe to the KOH aqueous solution. Under stirring conditions, add chlorosulfonic acid dropwise to the three-necked flask, and the acidic gas generated during the reaction is absorbed by the KOH aqueous solution. After all the chlorosulfonic acid has been added, continue stirring for 0.5 hours. Take out the white solid in the three-necked flask, which is the modified ultra-large pore silica gel catalyst B.

[0082] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst B is 314 m 2 / g, the pore volume is 1.5mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 2.8nm and the second most probable pore size of 31nm.

[0083] In addition, the surface sulfonic acid groups of the modified ultra-macroporous silica catalyst B are 1.8 mmol / g.

[0084] (3) Catalyst reaction performance evaluation

[0085] The esterification performance of catalyst B was tested according to the method of step (3) in Example 1. The oleic acid conversion rate was 98.2%, and the selectivity of methyl oleate was 99.3%.

[0086] Example 3

[0087] (1) Preparation of ultra-macroporous silica gel

[0088] 50 g of 15 wt% water glass, 5 g of 12 wt% sulfuric acid solution, 20 g of n-butanol and 3 g of glycerol were mixed at 40°C and the pH value was adjusted to 4 with 98 wt% sulfuric acid, and the contact reaction was carried out for 1.0 h. The solid matter obtained by filtration was then washed 4 times with distilled water to obtain a silica gel filter cake.

[0089] 10g of the silica gel filter cake prepared above was placed in a 100mL ball mill, wherein the ball mill was made of polytetrafluoroethylene, the grinding balls were made of agate, the diameter of the grinding balls was 2mm, the number was 2, and the rotation speed was 500r / min. The ball mill was closed and ball milled for 10h at a temperature of 30°C in the ball mill. The ball-milled silica gel filter cake was spray dried at 150°C and a rotation speed of 13000r / min to obtain ultra-large pore silica gel C.

[0090] The specific surface area of ​​super-macroporous silica gel C is 321m 2 / g, pore volume 1.4cm 3 / g, the first most probable pore size is 2.9nm, and the second most probable pore size is 30nm.

[0091] (2) Preparation of modified ultra-macroporous silica catalyst

[0092] Under room temperature, add 12 grams of the above-mentioned ultra-large pore silica gel to a three-necked flask equipped with a constant pressure funnel and an exhaust gas outlet pipe, and install a mechanical stirring device. Add 10.8 grams of chlorosulfonic acid to the constant pressure funnel, and connect the exhaust gas outlet pipe to the KOH aqueous solution. Under stirring conditions, add chlorosulfonic acid dropwise to the three-necked flask, and the acidic gas generated during the reaction is absorbed by the KOH aqueous solution. After all the chlorosulfonic acid has been added, continue stirring for 3 hours. Take out the white solid in the three-necked flask, which is the modified ultra-large pore silica gel catalyst C.

[0093] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst C is 235 m 2 / g, the pore volume is 1.0mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 2.0nm and the second most probable pore size of 25nm.

[0094] In addition, the surface sulfonic acid groups of the modified ultra-macroporous silica catalyst C are 2.2 mmol / g.

[0095] (3) Catalyst reaction performance evaluation

[0096] The esterification performance of catalyst C was tested according to the method of step (3) in Example 1. The oleic acid conversion rate was 98.7%, and the selectivity of methyl oleate was 99.0%.

[0097] Example 4

[0098] (1) Preparation of ultra-macroporous silica gel

[0099] 50 g of 15 wt% water glass, 18 g of 12 wt% sulfuric acid solution, 22 g of n-butanol and 2 g of glycerol were mixed at 20°C and the pH value was adjusted to 1.5 with 98 wt% sulfuric acid, and the contact reaction was carried out for 1.5 hours. The solid matter obtained by filtration was then washed 8 times with distilled water to obtain a silica gel filter cake.

[0100] 10 g of the silica gel filter cake prepared above was placed in a 100 mL ball mill, wherein the ball mill was made of polytetrafluoroethylene, the grinding ball was made of agate, the diameter of the grinding ball was 3 mm, the number was 1, and the rotation speed was 400 r / min. The ball mill was sealed and ball milled for 5 h at a temperature of 60° C. The ball milled silica gel filter cake was spray dried at 200° C. and a rotation speed of 12000 r / min to obtain ultra-large pore silica gel D.

[0101] The specific surface area of ​​super-macroporous silica gel D is 220 m 2 / g, pore volume 1.2cm 3 / g, the first most probable pore size is 2.0nm, and the second most probable pore size is 25nm.

[0102] (2) Preparation of modified ultra-macroporous silica catalyst

[0103] Under room temperature, add 12 grams of the above-mentioned ultra-large pore silica gel D to a three-necked flask equipped with a constant pressure funnel and an exhaust gas outlet pipe, and install a mechanical stirring device. Add 8.5 grams of chlorosulfonic acid to the constant pressure funnel, and connect the exhaust gas outlet pipe to the NaOH aqueous solution. Under stirring conditions, add chlorosulfonic acid dropwise to the three-necked flask, and the acidic gas generated during the reaction is absorbed by the NaOH aqueous solution. After all the chlorosulfonic acid has been added, continue stirring for 1 hour. Take out the white solid in the three-necked flask, which is the modified ultra-large pore silica gel catalyst D.

[0104] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst D is 137 m 2 / g, the pore volume is 0.7mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 1.3nm and the second most probable pore size of 20nm.

[0105] In addition, the surface sulfonic acid groups of the modified ultra-macroporous silica catalyst D are 1.4 mmol / g.

[0106] (3) Catalyst reaction performance evaluation

[0107] The catalytic performance of Catalyst D was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The oleic acid conversion rate was 96.6%, and the selectivity of methyl oleate was 98.4%.

[0108] Example 5

[0109] Ultra-macroporous silica gel A was prepared in the same manner as step (1) in Example 1.

[0110] (2) Preparation of modified ultra-macroporous silica catalyst

[0111] At room temperature, add 12 grams of the above-mentioned ultra-large pore silica gel A to a three-necked flask equipped with a constant pressure funnel and an exhaust gas outlet pipe, and install a mechanical stirring device. Add 3.6 grams of fluorosulfonic acid to the constant pressure funnel, and connect the exhaust gas outlet pipe to the NaOH aqueous solution. Under stirring conditions, add fluorosulfonic acid dropwise to the three-necked flask, and the acidic gas generated during the reaction is absorbed by the NaOH aqueous solution. After all the fluorosulfonic acid has been added, continue stirring for 1 hour. Take out the white solid in the three-necked flask, which is the modified ultra-large pore silica gel catalyst E.

[0112] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst E is 309 m 2 / g, the pore volume is 1.5mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 2.7nm and the second most probable pore size of 30nm.

[0113] In addition, the surface sulfonic acid group of the modified ultra-macroporous silica catalyst E is 1.0 mmol / g.

[0114] The catalytic performance of Catalyst E was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The oleic acid conversion rate was 94.5%, and the selectivity of methyl oleate was 97.0%.

[0115] Example 6

[0116] Ultra-macroporous silica gel A was prepared in the same manner as step (1) in Example 1.

[0117] (2) Preparation of modified ultra-macroporous silica catalyst

[0118] Under room temperature, add 12 grams of the above-mentioned ultra-large pore silica gel A to a three-necked flask equipped with a constant pressure funnel and an exhaust gas outlet pipe, and install a mechanical stirring device. Add 14.4 grams of bromosulfonic acid to the constant pressure funnel, and connect the exhaust gas outlet pipe to the KOH aqueous solution. Under stirring conditions, add bromosulfonic acid dropwise to the three-necked flask, and the acidic gas generated during the reaction is absorbed by the KOH aqueous solution. After all the bromosulfonic acid has been added dropwise, continue stirring for 1 hour. Take out the white solid in the three-necked flask, which is the modified ultra-large pore silica gel catalyst F.

[0119] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst F is 197 m 2 / g, the pore volume is 0.8mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 1.6nm and the second most probable pore size of 22nm.

[0120] In addition, the surface sulfonic acid groups of the modified ultra-macroporous silica catalyst F are 3.0 mmol / g.

[0121] The catalytic performance of Catalyst F was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The oleic acid conversion rate was 94.1%, and the selectivity of methyl oleate was 97.3%.

[0122] Comparative Example 1

[0123] Ultra-macroporous silica gel A was prepared in the same manner as step (1) in Example 1.

[0124] (2) Preparation of modified ultra-macroporous silica catalyst

[0125] At room temperature, add 12 grams of the above-mentioned ultra-large pore silica gel A to a three-necked flask equipped with a constant pressure funnel and an exhaust gas outlet pipe, and install a mechanical stirring device. Add 1.2 grams of fluorosulfonic acid to the constant pressure funnel, and connect the exhaust gas outlet pipe to the NaOH aqueous solution. Under stirring conditions, add fluorosulfonic acid dropwise to the three-necked flask, and the acidic gas generated during the reaction is absorbed by the NaOH aqueous solution. After all the fluorosulfonic acid has been added, continue stirring for 1 hour. Take out the white solid in the three-necked flask, which is the modified ultra-large pore silica gel catalyst D1.

[0126] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst D1 is 328 m 2 / g, the pore volume is 1.6mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 3.0nm and the second most probable pore size of 32nm.

[0127] In addition, the surface sulfonic acid group of the modified ultra-macroporous silica catalyst D1 is 0.4 mmol / g.

[0128] The catalytic performance of catalyst D1 was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The oleic acid conversion rate was 70.1%, and the selectivity of methyl oleate was 90.6%.

[0129] Comparative Example 2

[0130] Ultra-macroporous silica gel A was prepared in the same manner as step (1) in Example 1.

[0131] (2) Preparation of modified ultra-macroporous silica catalyst

[0132] At room temperature, add 12 grams of the above-mentioned ultra-large pore silica gel A to a three-necked flask equipped with a constant pressure funnel and an exhaust gas outlet pipe, and install a mechanical stirring device. Add 24 grams of bromosulfonic acid to the constant pressure funnel, and connect the exhaust gas outlet pipe to the KOH aqueous solution. Under stirring conditions, add bromosulfonic acid dropwise to the three-necked flask, and the acidic gas generated during the reaction is absorbed by the KOH aqueous solution. After all the bromosulfonic acid has been added, continue stirring for 1 hour. Take out the white solid in the three-necked flask, which is the modified ultra-large pore silica gel catalyst D2.

[0133] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst D2 is 95 m 2 / g, the pore volume is 0.5mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 0.7nm and the second most probable pore size of 14nm.

[0134] In addition, the surface sulfonic acid groups of the modified ultra-macroporous silica catalyst D2 are 4.2 mmol / g.

[0135] The catalytic performance of catalyst D2 was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The oleic acid conversion rate was 76.8%, and the selectivity of methyl oleate was 92.3%.

[0136] Comparative Example 3

[0137] Step (1) in Example 1 was cancelled, and the ultra-large pore silica gel A in step (2) in Example 1 was replaced with commercially available silica (purchased from Nanjing Baoket New Materials Co., Ltd., with a specific surface area of ​​180 m 2 / g, pore volume of 0.3ml / g, average pore diameter of 14nm), to obtain catalyst D3.

[0138] In addition, the specific surface area of ​​the modified catalyst D3 is 143 m 2 / g, the pore volume is 0.2mL / g, the pore size is unimodal, and the most probable pore size is 13nm.

[0139] In addition, the surface sulfonic acid group of the modified catalyst D3 was 0.9 mmol / g.

[0140] The catalytic performance of catalyst D3 was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The oleic acid conversion rate was 91.4%, and the selectivity of methyl oleate was 95.2%.

[0141] Comparative Example 4

[0142] Ultra-large pore silica gel A was prepared in the same manner as step (1) in Example 1, step (2) in Example 1 was omitted, and the esterification catalytic performance of ultra-large pore silica gel A was tested using the catalyst.

[0143] The catalytic performance of ultra-large pore silica gel A was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The oleic acid conversion rate was 20.1%, and the selectivity of methyl oleate was 52.4%.

[0144] Comparative Example 5

[0145] Ultra-macroporous silica gel A was prepared in the same manner as step (1) in Example 1;

[0146] The modified ultra-large pore silica gel catalyst D5 was prepared in the same manner as step (2) in Example 1, except that "8.5 g of chlorosulfonic acid" was replaced by "7.2 g of concentrated sulfuric acid" to obtain the modified ultra-large pore silica gel catalyst D5.

[0147] In addition, the specific surface area of ​​the modified ultra-macroporous silica catalyst D5 is 315 m 2 / g, the pore volume is 1.5mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 2.8nm and the second most probable pore size of 31nm.

[0148] In addition, the surface sulfonic acid group of the modified ultra-macroporous silica catalyst D5 is 0.8 mmol / g.

[0149] The catalytic performance of catalyst D5 was tested using the same esterification reaction performance evaluation method as in step (3) of Example 1. The oleic acid conversion rate was 90.5%, and the selectivity of methyl oleate was 94.2%.

[0150] It can be seen from the above results that the modified ultra-macroporous silica gel catalyst provided by the present invention can directly convert oleic acid and methanol to produce methyl oleate, thereby obtaining a higher oleic acid conversion rate and methyl oleate selectivity.

[0151] In Comparative Example 1, the amount of halosulfonic acid used in the preparation process of the modified ultra-large porous silica gel catalyst is too low, resulting in poor effect of the sulfonation process. The number of sulfonic acid groups on the surface of the prepared catalyst is relatively small, and the same weight of catalyst active sites are insufficient during the reaction process, resulting in low oleic acid conversion rate and low selectivity for methyl oleate.

[0152] In Comparative Example 2, the amount of halosulfonic acid used in the preparation process of the modified ultra-large porous silica gel catalyst is too high, the sulfonic acid groups on the surface of the prepared catalyst are aggregated and unevenly dispersed on the ultra-large porous silica gel, and some active centers cannot effectively play a catalytic role during the reaction, resulting in low oleic acid conversion rate and low selectivity of methyl oleate.

[0153] In Comparative Example 3, the ultra-large pore silica specifically defined in the present invention is not used, but commercial silica is used. Since the pore structure of commercial silica is quite different from that of ultra-large pore silica, the pore volume is small. The sulfonic acid groups are unevenly dispersed on the surface of commercial silica, resulting in low oleic acid conversion and low selectivity of methyl oleate.

[0154] In Comparative Example 4, unmodified ultra-large porous silica gel A was used as a catalyst to catalyze the esterification reaction of oleic acid. Since the surface acid sites of the ultra-large porous silica gel material were extremely weak, the esterification reaction could not be effectively catalyzed, resulting in extremely low oleic acid conversion rate and extremely low selectivity for methyl oleate.

[0155] In Comparative Example 5, concentrated sulfuric acid was used instead of halosulfonic acid as the modification agent. Since concentrated sulfuric acid molecules have poor adhesion to the silica gel surface, the number of sulfonic acid groups on the catalyst surface is small; therefore, the oleic acid conversion rate is low and the selectivity of methyl oleate is low.

[0156] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A modified ultra-macroporous silica catalyst, characterized in that: The modified ultra-macroporous silica catalyst is obtained by sulfonating ultra-macroporous silica, and the surface sulfonic acid groups of the modified ultra-macroporous silica catalyst are 1-3 mmol / g.

2. The modified ultra-macroporous silica catalyst according to claim 1, wherein: The surface sulfonic acid groups of the modified ultra-macroporous silica catalyst are 1.5-2.5 mmol / g.

3. The modified ultra-macroporous silica catalyst according to claim 1 or 2, wherein: The average particle diameter of the ultra-large pore silica gel is 20-60 μm, and the specific surface area is 150-600 m 2 / g, pore volume is 1-2.5mL / g, pore size is bimodal, and the two peaks correspond to the first most probable pore size of 1-4.5nm and the second most probable pore size of 20-50nm; Preferably, the average particle diameter of the ultra-large pore silica gel is 30-50 μm, and the specific surface area is 250-500 m 2 / g, the pore volume is 1.4-2mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 2.5-4nm and the second most probable pore size of 30-40nm.

4. The modified ultra-macroporous silica catalyst according to any one of claims 1 to 3, wherein The preparation method of the ultra-macroporous silica gel comprises: (1) in the presence of butanol and propylene glycol, contacting and mixing an inorganic silicon source with an acid agent, and filtering and washing the obtained mixture to obtain a silica gel filter cake; (2) ball milling and spray drying the silica gel filter cake to obtain ultra-large pore silica gel.

5. The modified ultra-macroporous silica catalyst according to claim 4, wherein: The inorganic silicon source may be one or more of water glass, sodium metasilicate and silica sol; and / or, the pH value of the mixture is 1.5-4.5, preferably 2-4; And / or, the weight ratio of the inorganic silicon source, the acid agent, butanol and glycerol can be 1: (0.05-0.5): (0.02-0.6): (0.02-0.6).

6. The modified ultra-macroporous silica catalyst according to claim 4 or 5, wherein: The mixing conditions include: temperature of 15-40°C and time of 1-3 hours; And / or, the ball milling conditions include: the rotation speed of the grinding balls is 300-500 r / min, the temperature in the ball mill is 30-80° C., and the ball milling time is 2-10 hours; And / or, the spray drying conditions include: a temperature of 100-300° C. and a rotation speed of 10000-15000 r / min.

7. The modified ultra-macroporous silica catalyst according to any one of claims 1 to 6, wherein: The specific surface area of ​​the modified ultra-macroporous silica catalyst is 100-500m 2 / g, the pore volume is 0.6-1.8mL / g, the pore size is bimodal, and the two peaks correspond to the first most probable pore size of 0.8-4.0nm and the second most probable pore size of 15-45nm.

8. A method for preparing a modified ultra-macroporous silica catalyst, characterized in that: The preparation method comprises: contacting ultra-large-porous silica gel with halosulfonic acid for sulfonation treatment to obtain a modified ultra-large-porous silica gel catalyst; Wherein, the weight ratio of the ultra-large pore silica gel to the halosulfonic acid is 1:(0.3-1.2).

9. The preparation method according to claim 8, wherein: The weight ratio of the ultra-large pore silica gel to the halosulfonic acid is 1:(0.5-0.9); And / or, the average particle diameter of the ultra-large pore silica gel is 20-60 μm, and the specific surface area is 150-600 m 2 / g, pore volume is 1-2.5mL / g, pore size is bimodal, and the two peaks correspond to the first most probable pore size of 1-4.5nm and the second most probable pore size of 20-50nm; Preferably, the average particle diameter of the ultra-large pore silica gel is 30-50 μm, and the specific surface area is 250-500 m 2 / g, pore volume is 1.4-2mL / g, pore size is bimodal, and the two peaks correspond to the first most probable pore size of 2.5-4nm and the second most probable pore size of 30-40nm; and / or, the halosulfonic acid is selected from one or more of fluorosulfonic acid, chlorosulfonic acid, bromosulfonic acid and iodosulfonic acid, preferably chlorosulfonic acid; And / or, the contacting conditions include: reaction temperature of 0-40° C., reaction time of 0.2-8 hours.

10. A modified ultra-macroporous silica catalyst prepared by the preparation method according to claim 8 or 9.

11. Use of the modified ultra-macroporous silica catalyst according to any one of claims 1 to 6 and 10 in the synthesis reaction of methyl oleate.

12. The use according to claim 11, wherein: The application comprises: contacting the modified ultra-macroporous silica catalyst, oleic acid and methanol to react; Preferably, the conditions for the contact reaction include: a reaction temperature of 40-100° C. and a reaction time of 1-12 h; And / or, the weight ratio of the modified ultra-macroporous silica catalyst, oleic acid and methanol is 1:(2-50):(1-10).

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