Supported esterification catalyst, its preparation method and application in methyl methacrylate synthesis reaction

Abstract

The application relates to the fine chemical technology field and discloses a supported esterification catalyst, a preparation method thereof and application of the supported esterification catalyst in a methyl methacrylate synthesis reaction. The supported esterification catalyst comprises a spherical composite carrier and an alkyl sulfonate supported on the spherical composite carrier; the spherical composite carrier is an alumina-MCM-41 composite material, and the content of the spherical composite carrier is 45-75% by weight and the content of the alkyl sulfonate is 25-55% by weight based on the total weight of the supported esterification catalyst. The catalyst is used in a methyl methacrylate esterification reaction, and higher methyl methacrylate conversion rate and methyl methacrylate selectivity can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fine chemical technology, in particular, to a supported esterification catalyst, a preparation method thereof and application thereof in the synthesis reaction of methyl methacrylate. BACKGROUND

[0002] As an important organic chemical product and raw material, the industrial production level and capacity of methyl methacrylate (MMA) have an important influence on the development of China's chemical industry. MMA is mainly used in the industries of organic glass (PMMA), paint, textile, adhesive, leather, papermaking, floor polishing, unsaturated resin modification, high-grade methyl methacrylate ester, wood preservative, printing and dyeing aid, and plastic plasticizer, etc. In recent years, the demand for MMA polymers, profiles, plates, coatings, emulsions, etc. at home and abroad is increasing, and the application field is continuously expanding, which promotes the rapid development of the MMA industry. At present, the production technology of methyl methacrylate in China is still in the initial stage. Developing methyl methacrylate esterification catalysts with independent intellectual property rights and supporting processes is the development demand of China's MMA production industry.

[0003] The esterification catalyst is the core technology of MMA production. For the esterification reaction of methacrylic acid and methanol, the traditional production process using inorganic acids such as sulfuric acid, phosphoric acid, and boric acid as catalysts is gradually eliminated, and the use of organic acids such as p-toluenesulfonic acid as catalyst also has the disadvantages of serious environmental pollution, low selectivity, and difficult product separation. Compared with the above, the esterification catalyst for heterogeneous reaction is a relatively active research field. In the latest reports, researchers have been trying to use acidic resins, organotin compounds, rare earth solid superacids, and Lewis acids as catalysts for the synthesis of carboxylic acid esters, and have achieved meaningful experimental results. At present, acid cation exchange resins are widely used in the production of methyl methacrylate in industry. The cation exchange resin shows good stability, high selectivity, low cost, and easy separation in the esterification reaction. However, the cation exchange resin itself has poor heat resistance (generally not higher than 250℃ will decompose), small specific surface area and pore volume, and the cation exchange resin is easy to swell, which has poor reaction activity as an esterification catalyst and low ester yield. With the increasing demand for MMA, the synthesis of methyl methacrylate by using green and environmentally friendly process has broad prospects.

[0004] At present, the supported esterification catalyst is paid more and more attention in the synthesis of methyl methacrylate. For researchers, it is an important work direction in the future to develop esterification catalysts with excellent performance, improve reaction efficiency, and inhibit the generation of by-products. SUMMARY

[0005] The application aims to overcome the problems of low conversion rate of methacrylic acid and low yield of methyl methacrylate in the current methyl methacrylate production process, and provides a supported esterification catalyst, a preparation method thereof and application thereof in a methyl methacrylate synthesis reaction.

[0006] To achieve the above-mentioned purpose, the first aspect of the application provides a supported esterification catalyst, wherein the supported esterification catalyst comprises a spherical composite carrier and an alkyl sulfonate salt supported on the spherical composite carrier; the spherical composite carrier is an alumina-MCM-41 composite material, and the content of the spherical composite carrier is 45-75% by weight and the content of the alkyl sulfonate salt is 25-55% by weight based on the total weight of the supported esterification catalyst.

[0007] The second aspect of the application provides a preparation method of the aforementioned supported esterification catalyst, wherein the preparation method comprises:

[0008] (1) mixing a spherical composite carrier, sodium alkyl sulfonate and deionized water to obtain a mixture 1;

[0009] (2) performing a contact reaction of an aqueous solution of a metal salt with the mixture 1 to obtain a mixture 2;

[0010] (3) filtering the mixture 2 to obtain a solid product, and then sequentially performing washing and drying treatment on the solid product to obtain the supported esterification catalyst.

[0011] The third aspect of the application provides application of the aforementioned supported esterification catalyst in a methyl methacrylate synthesis reaction.

[0012] Compared with the prior art, the technical scheme of the application has the following advantages:

[0013] (1) The supported esterification catalyst provided by the application is spherical, uniform in size, smooth in surface, high in mechanical strength, stable in structure, good in high-temperature resistance, and does not deform or swell during the reaction.

[0014] (2) The supported esterification catalyst provided by the application is easy to obtain raw materials, the preparation method is simple, the conditions are easy to control, and the product has good repeatability.

[0015] (3) The catalyst provided by the application has mild process conditions when used for synthesizing methyl methacrylate, and has low requirements for the reaction device. The conversion rate of methacrylic acid is high, and the selectivity of methyl methacrylate is high.

[0016] Other features and advantages of the present application will be explained in detail in the following detailed description of the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a small-angle XRD pattern of the alumina-MCM-41 composite support A prepared in Example 1 of the present application;

[0018] Figure 2 is a wide-angle XRD pattern of the alumina-MCM-41 composite support A prepared in Example 1 of the present application;

[0019] Figure 3 is a pore size distribution pattern of the alumina-MCM-41 composite support A prepared in Example 1 of the present application;

[0020] Figure 4 is a photograph of the alumina-MCM-41 composite support A prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values should be interpreted as approximately between the stated values and include values near the stated values. For ranges comprising two or more parameters, any combination of these parameters within the stated range is also contended unless the context clearly indicates otherwise. For example, a range of "from 1 to 10" is intended to include any number between (and the unit includes the number itself) 1 and 10, for example, 1.1, 1.2,... 9.9, or 10.0.

[0022] As described previously, the first aspect of the present application provides a supported esterification catalyst, wherein the supported esterification catalyst comprises a spherical composite support and an alkyl sulfonate salt supported on the spherical composite support; the spherical composite support is an alumina-MCM-41 composite material, and the content of the spherical composite support is 45-75% by weight and the content of the alkyl sulfonate salt is 25-55% by weight, based on the total weight of the supported esterification catalyst.

[0023] The inventors of the present application found that in the prior art, esterification catalysts for producing methyl methacrylate are classified into two categories, i.e. homogeneous catalysts and heterogeneous catalysts. The homogeneous catalysts mainly include inorganic acid solutions and organic acids, and the heterogeneous catalysts mainly include solid acids and cation exchange resins. The homogeneous catalysts have the advantages of low price and good catalytic activity, but are gradually eliminated due to the problems of difficult separation of products from catalysts, more side reactions, and easy corrosion of equipment. The solid acid esterification catalysts solve the problems of difficult separation of products and serious corrosion of equipment, but are rarely applied to industrial production due to the problems of poor catalytic activity, high reaction temperature, and low product selectivity. Compared with the above catalysts, the use of acidic cation exchange resins as esterification catalysts to produce methyl methacrylate is the main process currently applied in industry. The resin catalysts have the advantages of high selectivity, low cost, and easy separation, but have the problems of low yield of methyl methacrylate in the esterification reaction of methacrylic acid and poor high-temperature resistance. The resin is an organic polymer material, which is easy to swell in organic solvents and is easy to deform or even decompose in a high-temperature environment, which is the main reason for the poor temperature resistance of the resin catalyst. Developing a new solid catalyst system to compensate for the performance defects of the resin catalyst is a good way to solve the problem.

[0024] Lewis acid catalysts are valued for their high activity, good selectivity, and mild reaction conditions, but ordinary Lewis acids are not stable in water and are easy to react with water to lose activity. The salt formed by combining Lewis acid and surfactant is called green Lewis acid because it is not easy to hydrolyze, and its catalytic effect in organic synthesis is attracting more and more attention. If a green Lewis acid that is not easy to dissolve in water is directly used as a catalyst in the synthesis of methyl methacrylate, the catalytic efficiency may be reduced due to uneven dispersion. As long as a suitable carrier is selected to disperse the catalyst well, the above problems can be solved and the efficiency of the catalyst can be improved. If the material used as the carrier not only has a large specific surface area, pore volume, and pore size, but also has a stable skeletal structure, it can avoid the structural defects of the resin catalyst, such as easy swelling and easy thermal decomposition, and is expected to obtain a methyl methacrylate esterification catalyst with superior catalytic performance.

[0025] If a load-type green Lewis acid esterification catalyst with excellent performance is to be obtained, a new material with excellent structural characteristics is first selected as a catalyst carrier. The MCM-41 full-silicon mesoporous molecular sieve has the structural characteristics of long-range ordered pore structure, large specific surface area, large pore size and large pore volume, and is beneficial to the diffusion of large molecule reactants and products in the esterification reaction. The MCM-41 mesoporous molecular sieve is suitable as a carrier of the esterification catalyst, but has poor viscosity and is not easy to be shaped. In industrial production, the solid-phase esterification catalyst is to be shaped before being applied, for example, the resin catalyst is generally spherical. The spherical catalyst has the advantages of high bulk density, large loading capacity and processing capacity, low abrasion, small dust during loading, fast mass transfer, high adsorption efficiency or reaction efficiency and the like.

[0026] The inventors of the present application found in the development of the esterification catalyst that if the MCM-41 mesoporous molecular sieve is mixed with an aluminum-containing material with good viscosity in a certain proportion to be acidified into a sol, and the sol is prepared into an alumina-MCM-41 composite carrier by a specific shaping method. The carrier belongs to an inorganic structure, will not swell and deform in an organic solvent, and has good temperature resistance. After the alkyl sulfonate is in-situ loaded on the alumina-MCM-41 composite carrier, an esterification catalyst with good mechanical strength can be obtained. The catalyst can exhibit good catalytic activity and methyl methacrylate selectivity when used in the esterification of methyl methacrylate.

[0027] According to the present application, preferably, the content of the spherical composite carrier is 50-70% by weight and the content of the alkyl sulfonate is 30-50% by weight based on the total weight of the load-type esterification catalyst; more preferably, the content of the composite carrier is 53-66% by weight and the content of the alkyl sulfonate is 34-47% by weight based on the total weight of the load-type esterification catalyst; and more preferably, the content of the composite carrier is 54.8-65.3% by weight and the content of the alkyl sulfonate is 34.7-45.2% by weight based on the total weight of the load-type esterification catalyst. In the present application, the use of the specific content of the spherical composite carrier and the alkyl sulfonate can make the prepared catalyst have better catalytic activity and ester selectivity when used in the esterification of methyl methacrylate.

[0028] According to the present application, the alkyl sulfonate is a linear alkyl sulfonate and / or a branched alkyl sulfonate; preferably, the alkyl sulfonate is a linear alkyl sulfonate; preferably, the alkyl in the alkyl sulfonate is selected from one or more of heptane, decyl, dodecyl and tetradecyl; and more preferably, the sulfonate in the alkyl sulfonate is lanthanum sulfonate and / or cerium sulfonate.

[0029] According to the present application, the specific surface area of the alumina-MCM-41 composite carrier is 300-800m2 / g, and the pore volume is 0.5-1.2 cm 3 / g, the bulk density is 0.58-0.65 g / ml, the average particle diameter is 1.6-1.8 mm, and the average particle strength is higher than 30 N; preferably, the specific surface area of the alumina-MCM-41 composite carrier is 600-780 m 2 / g, and the pore volume is 0.6-1 cm 3 / g, the bulk density is 0.58-0.64 g / ml, the average particle diameter is 1.61-1.8 mm, and the average particle strength is 30-45 N; more preferably, the specific surface area of the alumina-MCM-41 composite carrier is 649-752 m 2 / g, and the pore volume is 0.65-0.73 cm 3 / g, the bulk density is 0.59-0.63 g / ml, the average particle diameter is 1.62-1.79 mm, and the average particle strength is 35.1-41.7 N. In the present application, the alumina-MCM-41 composite carrier with the specific parameters described above can make the prepared catalyst have better catalytic activity and ester selectivity when used in the methacrylate esterification reaction.

[0030] According to the present application, the preparation method of the alumina-MCM-41 composite carrier comprises:

[0031] (1) contacting and mixing an alumina precursor, MCM-41 full-silica mesoporous molecular sieve, an acidic aqueous solution, and a co-extrusion agent, and performing pelletizing treatment on the obtained mixture to obtain a spherical precursor;

[0032] (2) drying and calcining the spherical precursor to obtain a spherical composite carrier.

[0033] According to the present application, in step (1), the alumina precursor can be selected from one or more of pseudoboehmite, aluminum hydroxide gel, aluminum sol, gibbsite, or bayerite. In the present application, the alumina precursor can be obtained by commercial purchase. In particular, in the present application, the alumina precursor includes: a German original imported pseudoboehmite powder with a model number of SB (purchased from Beijing Asia Pacific Aohua Chemical Auxiliary Co., Ltd., the specific surface area is 241 m 2 / g, and the pore volume is 0.53 cm 3 / g), a bayerite powder with a model number of BD-BS03 (purchased from Zibo Baida Chemical Co., Ltd. in Shandong, the specific surface area is 269 m 2 / g, and the pore volume is 0.41 cm 3 / g), and a pseudoboehmite powder with a model number of P-DF-03-LS (produced by Shandong Aluminum Co., Ltd., the specific surface area is 257 m 2 / g, and the pore volume is 0.32 cm3 one or more of (g).

[0034] According to the present application, the MCM-41 full-silica mesoporous molecular sieve can be a commercially available MCM-41 full-silica mesoporous molecular sieve product or a self-made MCM-41 full-silica mesoporous molecular sieve, preferably, the specific surface area of the MCM-41 full-silica mesoporous molecular sieve is 900-1300 m 2 / g, the pore volume is 0.8-1.4 cm 3 / g, and the average pore size is 2-4 nm; more preferably, the specific surface area of the MCM-41 full-silica mesoporous molecular sieve is 950-1200 m 2 / g, the pore volume is 0.9-1.3 cm 3 / g, and the average pore size is 2.5-3.5 nm; still more preferably, the specific surface area of the MCM-41 full-silica mesoporous molecular sieve is 993-1064 m 2 / g, the pore volume is 0.9-1.1 cm 3 / g, and the average pore size is 2.7-3.2 nm.

[0035] In the present application, the preparation of the MCM-41 full-silica mesoporous molecular sieve comprises:

[0036] (1) mixing hexadecyl trimethyl ammonium bromide, tetramethyl ammonium hydroxide and deionized water to obtain a first mixture;

[0037] (2) mixing tetramethyl orthosilicate and isopropyl alcohol to obtain a second mixture;

[0038] (3) slowly adding the second mixture into the first mixture for a crystallization reaction, and then washing, drying and calcining the obtained solid product to obtain the MCM-41 full-silica mesoporous molecular sieve.

[0039] According to the present application, the molar ratio of the amounts of tetramethyl ammonium hydroxide, hexadecyl trimethyl ammonium bromide, isopropyl alcohol and H2O is 1:(0.1-0.4):(0.1-0.4):(10-50).

[0040] According to the present application, the conditions of the first mixing and the second mixing are the same or different, and each comprises: mixing at room temperature for 10-120 minutes. Preferably, the mixing is carried out under stirring conditions, and the stirring conditions comprise: the stirring rate is 200-600 revolutions per minute.

[0041] According to the present application, the conditions of the slow adding comprise: the dropping speed of the mixed solution is 0.5-2 milliliters per minute.

[0042] According to the present application, the conditions of the crystallization comprise: the temperature is 20-50℃, and the time is 4-10 hours.

[0043] According to the present application, the drying condition comprises: temperature of 100-130℃, time of 4-12h.

[0044] According to the present application, the calcination condition comprises: temperature of 500-650℃, time of 3-8h.

[0045] According to the present application, the acid aqueous solution can be organic acid aqueous solution or inorganic acid aqueous solution, preferably, the acid aqueous solution is selected from one or more of formic acid aqueous solution, acetic acid aqueous solution, citric acid aqueous solution, nitric acid aqueous solution and hydrochloric acid aqueous solution, more preferably, the acid aqueous solution is nitric acid aqueous solution or citric acid aqueous solution; in the present application, the mass concentration of the acid aqueous solution is 1-20%, preferably 2-10%.

[0046] According to the present application, the extrusion aid is selected from one or more of sesbania powder, polyethylene glycol, polyvinyl alcohol, polyacrylamide and cellulose; preferably, the extrusion aid is sesbania powder.

[0047] Preferably, the weight ratio of the alumina precursor, the MCM-41 full-silica mesoporous molecular sieve, the extrusion aid and the acid aqueous solution is 1:(0.2-1):(0.02-0.5):(0.2-5); preferably, the weight ratio of the alumina precursor, the MCM-41 full-silica mesoporous molecular sieve, the extrusion aid and the acid aqueous solution is 1:(0.3-0.5):(0.07-0.12):(0.6-0.8).

[0048] According to the present application, in step (1), the alumina precursor, the MCM-41 full-silica mesoporous molecular sieve, the acid aqueous solution and the extrusion aid are contacted for mixing, and the mixing condition comprises: stirring rate of 50-300r / min, temperature of 20-60℃, time of 0.5-6h; preferably, stirring rate of 150-250r / min, temperature of 20-40℃, time of 0.5-1h.

[0049] According to the present application, in step (2), the drying condition comprises: temperature of 70-150℃, time of 3-24h; preferably, temperature of 100-130℃, time of 6-12h.

[0050] According to the present application, in step (2), the calcination condition comprises: temperature of 400-700℃, time of 2-30h; preferably, temperature of 550-700℃, time of 12-15h.

[0051] According to the present application, in step (1), the micro-pellet balling method comprises:

[0052] (1-1) extruding the mixture into a strip, and then cutting and extruding the strip into raw material balls;

[0053] (1-2) performing a shaping treatment on the raw material balls to obtain standard round balls;

[0054] (1-3) performing a screening on the standard round balls to obtain spherical precursors.

[0055] According to the present application, in step (1-1), the alumina precursor, the MCM-41 full-silica mesoporous molecular sieve, the acidic aqueous solution and the extrusion aid are uniformly mixed, and then the obtained mixture is transferred into a micro-ball making machine to extrude a long strip with a circular cross section, and then the long strip is cut and extruded into raw material balls; wherein the conditions for the extruding into a strip include that the extruding speed is 0.5-5 m / min, and the diameter of the circular cross section of the long strip is 1.5-3.0 mm; and the conditions for the cutting include that the cutting speed is 100-3500 particles per minute.

[0056] According to the present application, in step (1-2), the raw material balls are put into a micro-pellet shaping machine to be shaped into standard round balls; wherein the conditions for the shaping include that the tumbling time is 0.5-10 minutes per time, the tumbling frequency is 1-5 times, and the sample cavity rotation speed is 50-1400 r / min.

[0057] According to the present application, in step (1-3), the standard round balls are put into a micro-pellet screening machine to screen out spherical precursors with a suitable size.

[0058] According to the present application, in step (2), the drying conditions include that the temperature is 70-150℃, and the time is 3-24 h; preferably, the temperature is 100-130℃, and the time is 6-12 h.

[0059] According to the present application, in step (2), the calcining conditions include that the temperature is 400-700℃, and the time is 2-30 h; preferably, the temperature is 550-650℃, and the time is 12-15 h.

[0060] The second aspect of the present application provides a preparation method of the supported esterification catalyst as described above, wherein the preparation method comprises:

[0061] (1) mixing the spherical composite carrier, sodium alkyl sulfonate and deionized water to obtain a mixture 1;

[0062] (2) slowly adding an aqueous solution of a metal salt into the mixture 1 to perform a contact reaction, to obtain a mixture 2;

[0063] (3) filtering the mixture 2 to obtain a solid product, and sequentially performing a washing and drying treatment on the solid product to obtain the supported esterification catalyst.

[0064] According to the present application, in step (1), the sodium alkylsulfonate is sodium linear alkylsulfonate and / or sodium branched alkylsulfonate; preferably, the sodium alkylsulfonate is sodium linear alkylsulfonate; preferably, the alkyl in the sodium alkylsulfonate is selected from one or more of heptyl, decyl, dodecyl and tetradecyl.

[0065] According to the present application, in step (1), the weight ratio of the spherical composite carrier, the sodium alkylsulfonate and deionized water is 1:(0.1-5):(5-100), preferably 1:(0.2-3):(10-60).

[0066] According to the present application, in step (1), the mixing conditions of the spherical composite carrier, the sodium alkylsulfonate and deionized water include that the temperature can be 40-100℃, preferably 60-90℃; the time can be 1-50h, preferably 5-30h. Preferably, in order to achieve better mixing effect, rapid stirring or ultrasonic means can be used to improve the mixing efficiency during the mixing of the spherical composite carrier, the sodium alkylsulfonate and deionized water.

[0067] According to the present application, in step (2), the metal salt is selected from one or more of chloride, sulfate and nitrate of a metal; preferably, the metal is lanthanum and / or cerium; preferably, the concentration of the aqueous solution of the metal salt is 0.02-1.0mol / L, preferably 0.05-0.6mol / L.

[0068] According to the present application, in step (2), preferably, the weight ratio of the spherical composite carrier and the aqueous solution of the metal salt is 1:(50-500).

[0069] According to the present application, in step (2), preferably, the aqueous solution of the metal salt is added dropwise to the mixture for contact reaction, wherein the dropwise addition rate is 0.5-2.0mL / min.

[0070] According to the present application, in step (2), the contact reaction conditions of the mixture 1 and the aqueous solution of the metal salt include that the reaction temperature can be 40-100℃, preferably 60-90℃; the time can be 0.1-20h, preferably 0.5-10h. Preferably, in order to achieve better contact reaction effect, rapid stirring can be used during the contact reaction of the mixture 1 and the aqueous solution of the metal salt.

[0071] According to the present application, in step (3), there is no special requirement for the filtration, which can be a filtration mode known in the art, including gravity filtration, pressure filtration, vacuum filtration or centrifugal filtration. Preferably, the filtration process specifically includes using a suction filter bottle, vacuumizing the bottom side of the funnel or using a centrifugal filter to filter.

[0072] According to the present application, in step (3), the method for washing the solid product is not particularly required, for example: the solid product can be washed with deionized water, the volume ratio of deionized water to the solid product can be 5-20, and the washing times can be 2-8 times. Preferably, in order to achieve better washing effect, rapid stirring can be carried out during the mixing of deionized water and the solid product.

[0073] According to the present application, in step (3), the drying conditions include: the temperature can be 120-230℃, preferably 150-200℃; and the time can be 1-30h, preferably 3-20h.

[0074] The third aspect of the present application provides an application of the aforementioned supported esterification catalyst in the synthesis reaction of methyl methacrylate. The application method of the catalyst includes: methyl methacrylate and methanol are simultaneously contacted with the supported esterification catalyst.

[0075] In the present application, the contact conditions of the methyl methacrylate and methanol with the catalyst include: the temperature of the contact can be 40-150℃, preferably 60-120℃; the pressure of the contact can be 0.01-5.0MPa, preferably 0.1-3.0Mpa; the mass space velocity of the methyl methacrylate can be 0.01-30h -1 , preferably 0.1-10h -1 ; and the mass space velocity of the methanol can be 0.01-50h -1 , preferably 0.1-30h -1 .

[0076] The present application will be described in detail through the following examples.

[0077] In the following examples and comparative examples:

[0078] The wide-angle XRD test of the sample was carried out on an X-ray powder diffractometer of X’Pert MPD type of Philips Company in the Netherlands, Cu Kα target, scanning range 2θ=5°-90°. The small-angle XRD test of the sample was carried out on a high-power rotating target X-ray diffractometer of D8 ADVANCE type of BRUKER AXS Company in Germany, scanning range: 0.5°-10°.

[0079] The pore structure parameter analysis of the sample was carried out on an adsorptometer of ASAP2020-M+C type purchased from Micromeritics Company in the United States.

[0080] The specific surface area of the sample was calculated by BET method, and the pore volume was calculated by BJH model before the sample was measured, and the sample was vacuum degassed at 350℃ for 4 hours.

[0081] The elemental analysis experiment of the sample was performed on an Eagle III energy dispersive X-ray fluorescence spectrometer produced by EDAX Company in the United States.

[0082] The rotary evaporator was produced by IKA Company in Germany, and the model was RV10 digital.

[0083] The drying oven was produced by Shanghai Yiheng Scientific Instrument Co., Ltd., and the model was DHG-9030A.

[0084] The muffle furnace was produced by CARBOLITE Company, and the model was CWF1100.

[0085] The kneader was an FN-NH2 type kneader produced by Tianshui Huayuan Pharmaceutical Equipment Technology Co., Ltd.; the micro-sphere forming machine was an HWJ-100 type micro-sphere forming machine produced by Tianshui Huayuan Pharmaceutical Equipment Technology Co., Ltd.; the micro-pellet shaping machine was an FN-XZXJ type micro-pellet shaping machine produced by Tianshui Huayuan Pharmaceutical Equipment Technology Co., Ltd.; and the micro-pellet screening machine was an SWP-1200 type micro-pellet screening machine produced by Tianshui Huayuan Pharmaceutical Equipment Technology Co., Ltd.

[0086] The pseudo-boehmite powder with the model of SB was purchased from Beijing Yatopuohua Chemical Auxiliary Co., Ltd.; the diaspore powder with the model of BD-BS03 was purchased from Zibo Baida Chemical Co., Ltd. in Shandong; the pseudo-boehmite powder with the model of P-DF-03-LS was purchased from Shandong Aluminum Co., Ltd.; the MCM-41 full-silicon mesoporous molecular sieve with the model of NKF-11 was purchased from the Catalyst Factory of Nankai University; and the reagents used in the examples and comparative examples were purchased from the National Pharmaceutical Group Chemical Reagent Co., Ltd., and the purity of the reagents was analytical pure.

[0087] Example 1

[0088] (1) Preparation of the aluminum oxide-MCM-41 composite carrier

[0089] In a round-bottom flask, cetyltrimethylammonium bromide (CTAB), tetramethylammonium hydroxide (TMAOH) and deionized water were mixed and stirred for 30 minutes, and tetramethyl orthosilicate (TMOS) and isopropanol were fully mixed and then slowly added to the flask, wherein the molar ratio of TMOS: CTAB: isopropanol: H2O was 1:0.26:0.26:24. After stirring for 5 hours, the solid product was separated from the mother liquor, washed with deionized water until neutral, dried in air at 110°C for 5 hours, and finally calcined at 550°C for 5 hours to obtain the MCM-41 full-silicon mesoporous molecular sieve A. The specific surface area of the MCM-41 full-silicon mesoporous molecular sieve A was 1064 m 2 / g, the pore volume was 1.1 cm 3 / g, and the average pore size was 2.7 nm.

[0090] Mix 120 g of pseudo-boehmite powder of SB type, 60 g of MCM-41 all-silica mesoporous molecular sieve A, 85 g of dilute nitric acid with a concentration of 5%, and 10 g of sesbania powder, and transfer the mixture to a kneader to mix and stir until uniform. The kneading temperature is 35°C, the main shaft rotation speed of the kneader is 150 r / min, and the kneading time is 1 h. Put the uniformly mixed raw materials into the hopper of a micro-sphere forming machine, select an extrusion die with a pore size of 1.8 mm, adjust the extrusion speed to 2 m / min, and the cutting speed to 1200 particles / min, and extrude and cut the raw materials into small round particles. Put the above-mentioned small round particles into a micro-pellet shaping machine for shaping, and the shaping conditions are as follows: the rolling time is 3 minutes per time, the rolling times are 3 times, and the sample cavity rotation speed is 300 r / min. Put the standard round spherical raw material balls obtained after shaping into a micro-pellet screening machine to screen out spherical precursors with a size of 1.7 mm. Dry the spherical precursors at 110°C for 8 h, and then calcine them at 600°C for 15 h to obtain an alumina-MCM-41 composite carrier A.

[0091] The alumina-MCM-41 composite carrier A is characterized, and the structural parameters are listed in Table 1.

[0092] Figure 1 is the small-angle XRD pattern of the alumina-MCM-41 composite carrier A. The XRD spectrum has a very strong diffraction peak near 2θ = 2°, and three weaker peaks also appear near 2θ = 4°, 4.5°, and 6°. The four distinguishable diffraction peaks correspond to the (100), (110), (200), and (210) crystal planes, respectively, indicating that after calcination at 600°C, the MCM-41 all-silica mesoporous molecular sieve crystal phase of the alumina-MCM-41 composite carrier A does not change significantly, and still maintains a typical hexagonal phase mesoporous structure.

[0093] Figure 2 is the wide-angle XRD pattern of the alumina-MCM-41 composite carrier A. The main x-ray diffraction angles are: 2θ ≈ 37.2°, 39.4°, 46.1°, 60.5°, and 66.6°, which are consistent with the diffraction spectrum of γ-Al2O3, indicating that after calcination at 600°C, the pseudo-boehmite of SB type after dehydration presents a typical γ-Al2O3 crystal phase.

[0094] Figure 3 is the pore size distribution of the alumina-MCM-41 composite carrier A, and the pore size of the sample shows a bimodal distribution, with a first most probable pore size of 2.7 nm mainly contributed by the MCM-41 all-silica mesoporous molecular sieve, and a second most probable pore size of 17 nm mainly contributed by the alumina.

[0095] Figure 4is a photo of the alumina-MCM-41 composite support A. It can be seen that the support is white round ball, with good sphericity, smooth surface and uniform particle size.

[0096] (2) Preparation of the supported esterification catalyst

[0097] 10 g of the alumina-MCM-41 composite support A, 5 g of sodium dodecyl sulfonate and 400 g of deionized water were mixed and stirred at 75°C for 8 h until well mixed. While keeping the temperature of the mixture at 75°C, 180 mL of a 0.2 mol / L aqueous solution of lanthanum sulfate was slowly added to the mixture at a rate of 1.0 mL / min. After stirring at 75°C for 3 h, the temperature was lowered to room temperature. The mixture was left to stand at room temperature for 20 h. The solid product was obtained by filtration, washed with deionized water for 6 times and dried at 180°C for 20 h to obtain the supported esterification catalyst A.

[0098] The content of the alumina-MCM-41 composite support A was 58.7 wt% and the content of the lanthanum dodecyl sulfonate was 41.3 wt% based on the total weight of the supported esterification catalyst A.

[0099] (3) Evaluation of the reaction performance of the catalyst

[0100] The reaction performance of the catalyst was evaluated by esterification reaction in a fixed bed reactor. 5.0 g of the supported esterification catalyst A was loaded into a stainless steel fixed bed reactor with an inner diameter of 8 mm. The reaction temperature was 100°C, the reaction pressure was 0.3 MPa, the weight hourly space velocity (WHSV) of methyl methacrylate was 1.0 h -1 , the WHSV of methanol was 2.7 h -1 , and the reaction time was 20 h. After cooling, the product was analyzed by Agilent 7890A gas chromatograph equipped with FFAP capillary column and hydrogen flame detector (FID) by programmed temperature and quantitative analysis with correction factor. The conversion rate of methyl methacrylate was 97.8% and the selectivity of methyl methacrylate was 99.8%.

[0101] Example 2

[0102] (1) Preparation of the alumina-MCM-41 composite support

[0103] 100 g of boehmite powder with model number BD-BS03 and 50 g of MCM-41 full-silicon mesoporous molecular sieve with model number NKF-11 (purchased from Nankai University Catalyst Factory, wherein the specific surface area was 1018 m 2 / g, and the pore volume was 0.9 cm 3The mixture of 10 g of the alumina-MCM-41 composite support B, 4 g of sodium tetradecylsulfate and 200 g of deionized water was stirred at 60°C for 15 h to mix uniformly. While keeping the temperature of the mixture at 60°C, 350 mL of a cerium sulfate aqueous solution with a concentration of 0.1 mol / L was slowly added dropwise to the mixture, which was stirred at 60°C for 10 h and then cooled to room temperature. The mixture was allowed to stand at room temperature for 20 h. The solid product was obtained by filtration, washed with deionized water for 6 times and dried at 200°C for 5 h to obtain the supported esterification catalyst B.

[0104] The alumina-MCM-41 composite support B was characterized, and the structural parameters are listed in Table 1.

[0105] (2) Preparation of the supported esterification catalyst

[0106] The mixture of 10 g of the alumina-MCM-41 composite support B, 4 g of sodium tetradecylsulfate and 200 g of deionized water was stirred at 60°C for 15 h to mix uniformly. While keeping the temperature of the mixture at 60°C, 350 mL of a cerium sulfate aqueous solution with a concentration of 0.1 mol / L was slowly added dropwise to the mixture, which was stirred at 60°C for 10 h and then cooled to room temperature. The mixture was allowed to stand at room temperature for 20 h. The solid product was obtained by filtration, washed with deionized water for 6 times and dried at 200°C for 5 h to obtain the supported esterification catalyst B.

[0107] The content of the alumina-MCM-41 composite support B was 65.3% by weight, and the content of the cerium tetradecylsulfate was 34.7% by weight, based on the total weight of the supported esterification catalyst B.

[0108] (3) Evaluation of the reaction performance of the catalyst

[0109] The esterification reaction performance of the catalyst B was tested according to the method of step (3) in Example 1. The conversion rate of methacrylic acid was 97.4%, and the selectivity of methyl methacrylate was 99.6%.

[0110] Example 3

[0111] (1) Preparation of the alumina-MCM-41 composite support

[0112] In a round bottom flask, cetyltrimethylammonium bromide (CTAB), tetramethylammonium hydroxide (TMAOH) and deionized water were mixed and stirred for 30 minutes, and then tetramethyl orthosilicate (TMOS) and isopropanol were mixed thoroughly and slowly added into the flask, wherein the molar ratio of TMOS:CTAB:isopropanol:H2O was 1:0.4:0.4:50. After stirring for 8 hours, the solid product was separated from the mother liquor, washed with deionized water until neutral, dried in air at 130°C for 4 hours, and finally calcined at 600°C for 6 hours to obtain mesoporous molecular sieve C of MCM-41. The specific surface area of the mesoporous molecular sieve C of MCM-41 was 993 m 2 / g, the pore volume was 1.0 cm 3 / g, and the average pore size was 2.9 nm.

[0113] The 130 g of aluminum hydroxide gel of model TY-101, 40 g of mesoporous molecular sieve C of MCM-41, 85 g of 20% citric acid aqueous solution, and 10 g of sesbania powder were mixed and transferred into a kneader for stirring and mixing uniformly. The kneading temperature was 20°C, the main shaft rotation speed of the kneader was 200 r / min, and the kneading time was 0.5 h. The uniformly mixed raw materials were put into the hopper of a micro-sphere maker, the extrusion die with a pore diameter of 2.5 mm was selected, the extrusion speed was adjusted to 1 m / min, and the cutting speed was 500 particles / min, so that the raw materials were extruded into strips and then cut into round small particles. The round small particles were put into a micro-pellet shaper for shaping, and the shaping conditions were as follows: the rolling time was 2 minutes / time, the rolling times were 4 times, and the rotation speed of the sample cavity was 200 r / min. The standard round spherical raw material balls obtained after shaping were put into a micro-pellet screening machine to screen out spherical precursors with a size of 2.5 mm. The spherical precursors were dried at 100°C for 12 h, and then calcined at 550°C for 15 h to obtain the aluminum oxide-MCM-41 composite carrier C.

[0114] The aluminum oxide-MCM-41 composite carrier C was characterized, and the structural parameters are listed in Table 1.

[0115] (2) Preparation of supported esterification catalyst

[0116] 10 g of the aluminum oxide-MCM-41 composite carrier C, 5.2 g of sodium heptanesulfonate, and 500 g of deionized water were mixed and stirred at 90°C for 5 h to mix uniformly. While keeping the temperature of the mixture at 90°C, 100 mL of 0.4 mol / L lanthanum trichloride aqueous solution was slowly added into the mixture, and after stirring at 90°C for 1 h, the temperature was lowered to room temperature. The mixture was left to stand at room temperature for 20 h. The solid product was obtained by filtration, washed with deionized water for 6 times, and dried at 150°C for 20 h to obtain the supported esterification catalyst C.

[0117] The content of the alumina-MCM-41 composite carrier C is 54.8% by weight and the content of the lanthanum heptyl sulfonate is 45.2% by weight, based on the total weight of the supported esterification catalyst C.

[0118] (3) Catalyst reaction performance evaluation

[0119] The esterification reaction performance of the catalyst C was tested according to the method of step (3) in Example 1. The conversion rate of methacrylic acid was 97.2% and the selectivity of methyl methacrylate was 99.5%.

[0120] Example 4

[0121] The supported esterification catalyst D was prepared according to the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) in Example 1 were changed, specifically:

[0122] 10 g of the alumina-MCM-41 composite carrier A, 4.3 g of sodium dodecyl sulfonate and 400 g of deionized water were mixed and stirred at 75°C for 8 h until well mixed. While maintaining the temperature of the mixture at 75°C, 150 mL of a lanthanum sulfate aqueous solution with a concentration of 0.2 mol / L was slowly added at a drop rate of 1.0 mL / min to the above mixture, which was stirred at 75°C for 3 h and then cooled to room temperature. The mixture was left to stand at room temperature for 20 h. The solid product was obtained by filtration, washed with deionized water for 6 times and dried at 180°C for 20 h to obtain the supported esterification catalyst D.

[0123] The content of the alumina-MCM-41 composite carrier A is 69.8% by weight and the content of the lanthanum dodecyl sulfonate is 30.2% by weight, based on the total weight of the supported esterification catalyst D.

[0124] The catalytic performance of the catalyst D was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid was 96.1% and the selectivity of methyl methacrylate was 99.0%.

[0125] Example 5

[0126] The supported esterification catalyst was prepared according to the same method as in Example 2, except that the preparation conditions of the catalyst in step (2) in Example 2 were changed, specifically:

[0127] Mixing 10 g of the alumina-MCM-41 composite support B, 5.8 g of sodium tetradecyl sulfonate and 200 g of deionized water, stirring at 60 °C for 15 h, and mixing uniformly. Keeping the temperature of the mixture at 60 °C, slowly adding 250 mL of an aqueous cerium sulfate solution with a concentration of 0.2 mol / L to the above mixture, stirring at 60 °C for 10 h after the reaction, and then cooling to room temperature. Standing at room temperature for 20 h. Filtering to obtain a solid product, washing with deionized water for 6 times, and drying at 200 °C for 5 h to obtain a supported esterification catalyst E.

[0128] The content of the alumina-MCM-41 composite support B is 50% by weight, and the content of the cerium tetradecyl sulfonate is 50% by weight, based on the total weight of the supported esterification catalyst E.

[0129] The catalytic performance of the catalyst E is tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid is 95.8%, and the selectivity of methyl methacrylate is 98.8%.

[0130] Example 6

[0131] The supported esterification catalyst D is prepared according to the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) in Example 1 are changed, specifically:

[0132] Mixing 10 g of the alumina-MCM-41 composite support A, 3.6 g of sodium dodecyl sulfonate and 400 g of deionized water, stirring at 75 °C for 8 h, and mixing uniformly. Keeping the temperature of the mixture at 75 °C, slowly adding 125 mL of an aqueous lanthanum sulfate solution with a concentration of 0.2 mol / L to the above mixture at a drop rate of 1.0 mL / min, stirring at 75 °C for 3 h after the reaction, and then cooling to room temperature. Standing at room temperature for 20 h. Filtering to obtain a solid product, washing with deionized water for 6 times, and drying at 180 °C for 20 h to obtain a supported esterification catalyst F.

[0133] The content of the alumina-MCM-41 composite support A is 75% by weight, and the content of the lanthanum dodecyl sulfonate is 25% by weight, based on the total weight of the supported esterification catalyst F.

[0134] The catalytic performance of the catalyst F is tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid is 94.1%, and the selectivity of methyl methacrylate is 98.3%.

[0135] Example 7

[0136] The supported esterification catalyst is prepared according to the same method as in Example 2, except that the preparation conditions of the catalyst in step (2) in Example 2 are changed, specifically:

[0137] Mixing 10 g of the alumina-MCM-41 composite support B, 6.4 g of sodium tetradecylsulfonate and 200 g of deionized water, stirring at 60 °C for 15 h, and mixing uniformly. Keeping the temperature of the mixture at 60 °C, slowly adding 275 mL of an aqueous cerium sulfate solution with a concentration of 0.2 mol / L to the above mixture, stirring at 60 °C for 10 h after reaction, and then cooling to room temperature. Standing at room temperature for 20 h. Filtering to obtain a solid product, washing with deionized water for 6 times, and drying at 200 °C for 5 h to obtain a supported esterification catalyst G.

[0138] The content of the alumina-MCM-41 composite support B is 45 wt% and the content of the cerium tetradecylsulfonate is 55 wt% based on the total weight of the supported esterification catalyst G.

[0139] The catalytic performance of the catalyst G is tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid is 94.5% and the selectivity of methyl methacrylate is 98.2%.

[0140] Table 1

[0141]

[0142]

[0143] Comparative Example 1

[0144] The supported esterification catalyst D1 is prepared according to the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) in Example 1 are changed, specifically:

[0145] Mixing 10 g of the alumina-MCM-41 composite support B, 6.4 g of sodium tetradecylsulfonate and 200 g of deionized water, stirring at 60 °C for 15 h, and mixing uniformly. Keeping the temperature of the mixture at 60 °C, slowly adding 275 mL of an aqueous cerium sulfate solution with a concentration of 0.2 mol / L to the above mixture, stirring at 60 °C for 10 h after reaction, and then cooling to room temperature. Standing at room temperature for 20 h. Filtering to obtain a solid product, washing with deionized water for 6 times, and drying at 200 °C for 5 h to obtain a supported esterification catalyst G.

[0146] The content of the alumina-MCM-41 composite support B is 45 wt% and the content of the cerium tetradecylsulfonate is 55 wt% based on the total weight of the supported esterification catalyst G.

[0147] The catalytic performance of the catalyst D1 is tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid is 82.8% and the selectivity of methyl methacrylate is 95.1%.

[0148] Comparative Example 2

[0149] The supported esterification catalyst was prepared in the same manner as in Example 2, except that the preparation conditions of the catalyst in step (2) in Example 2 were changed, specifically:

[0150] 10 g of the alumina-MCM-41 composite support B, 8.1 g of sodium tetradecyl sulfonate and 300 g of deionized water were mixed and stirred at 60 °C for 15 h to be uniformly mixed. While keeping the temperature of the mixture at 60 °C, 350 mL of an aqueous cerium sulfate solution with a concentration of 0.2 mol / L was slowly added to the above mixture, which was stirred at 60 °C for 10 h and then cooled to room temperature. It was left to stand at room temperature for 20 h. The solid product was obtained by filtration, washed with deionized water for 6 times and dried at 200 °C for 5 h to obtain the supported esterification catalyst D2.

[0151] The content of the alumina-MCM-41 composite support B was 30 wt% and the content of the cerium tetradecyl sulfonate was 70 wt% based on the total weight of the supported esterification catalyst D2.

[0152] The catalytic performance of the catalyst D2 was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid was 84.9% and the selectivity of methyl methacrylate was 94.6%.

[0153] Comparative Example 3

[0154] The supported esterification catalyst was prepared in the same manner as in Example 1, except that step (1) in Example 1 was cancelled and the alumina-MCM-41 composite support A in step (2) in Example 1 was replaced by a commercially available silica (purchased from Qingdao Hailang Silica Gel Dryer Factory, with a specific surface area of 329 m 2 / g and an average particle diameter of 1.5 mm) to obtain the catalyst D3.

[0155] The content of the commercially available silica was 58.7 wt% and the content of the alkyl sulfonate was 41.3 wt% based on the total weight of the catalyst D3.

[0156] The catalytic performance of the catalyst D3 was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid was 86.4% and the selectivity of methyl methacrylate was 95.8%.

[0157] Comparative Example 4

[0158] (1) Preparation of the alumina-MCM-41 composite support

[0159] Mix 50 g of boehmite powder with model number BD-BS03, 100 g of MCM-41 full-silica mesoporous molecular sieve with model number NKF-11 (purchased from Nankai University Catalyst Factory), 80 g of 10% acetic acid aqueous solution, and 12 g of polyethylene glycol, and transfer the mixture to a kneader to mix and stir until uniform. The kneading temperature is 35°C, the main shaft rotation speed of the kneader is 150 r / min, and the kneading time is 1 h. Put the mixed and stirred raw materials into the hopper of a micro-sphere forming machine, select an extrusion die with a pore diameter of 2.0 mm, adjust the extrusion speed to 5 m / min, and the cutting speed to 2000 particles / min, extrude the raw materials into strips and cut them into round small particles. Put the round small particles into a micro-pellet shaping machine to shape, and the shaping conditions are as follows: the rolling time is 0.5 min / time, the rolling times is 2 times, and the sample cavity rotation speed is 500 r / min. Put the standard round spherical raw material balls obtained after shaping into a micro-pellet screening machine to screen out spherical precursors with a size of 1.9 mm. Dry the spherical precursors at 110°C for 8 h, and then calcine them at 700°C for 12 h to obtain an alumina-MCM-41 composite carrier D4.

[0160] The alumina-MCM-41 composite carrier D4 is characterized, and the structural parameters are listed in Table 1.

[0161] The supported esterification catalyst D4 is prepared according to the method of step (2) in Example 1. The content of the alumina-MCM-41 composite carrier D4 is 58.7% by weight, and the content of the alkyl sulfonate is 41.3% by weight, based on the total weight of the catalyst D4.

[0162] The catalytic performance of the catalyst D4 is tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid is 89.7%, and the selectivity of methyl methacrylate is 95.4%.

[0163] Comparative Example 5

[0164] (1) Preparation of an alumina-MCM-41 composite carrier

[0165] Mix 120 g of pseudoboehmite powder with model number SB, 60 g of MCM-41 full-silica mesoporous molecular sieve A, 85 g of 5% dilute nitric acid, and 10 g of sesbania powder, and prepare spherical precursors by the mechanical rolling method, and screen out spherical precursors with a size of 1.7 mm. Dry the spherical precursors at 110°C for 8 h, and then calcine them at 600°C for 15 h to obtain an alumina-MCM-41 composite carrier D5.

[0166] The alumina-MCM-41 composite carrier D5 is characterized, and the structural parameters are listed in Table 1.

[0167] The supported esterification catalyst D5 was prepared according to the method of step (2) in Example 1. The content of the alumina-MCM-41 composite carrier D5 was 58.7% by weight and the content of the alkyl sulfonate was 41.3% by weight based on the total weight of the catalyst D5.

[0168] The catalytic performance of the catalyst D5 was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of methacrylic acid was 90.6% and the selectivity of methyl methacrylate was 95.8%.

[0169] Comparative Example 6

[0170] The supported esterification catalyst was prepared according to the same method as in Example 1, except that step (1) and step (2) in Example 1 were cancelled and the catalytic performance of the resin catalyst was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The resin catalyst was purchased from Kerry Environmental Science and Technology Co., Ltd. and the model number was D009.

[0171] The conversion rate of methacrylic acid was 90.2% and the selectivity of methyl methacrylate was 96.9%.

[0172] Comparative Example 7

[0173] The supported esterification catalyst D7 was prepared according to the same method as in Example 1, except that in step (2), lanthanum dodecyl sulfonate was not loaded, but sodium sulfate was loaded. The content of the alumina-MCM-41 composite carrier A was 58.7% by weight and the content of the sodium sulfate was 41.3% by weight based on the total weight of the supported esterification catalyst D7.

[0174] The catalytic performance of the catalyst D7 was tested according to the esterification reaction performance evaluation method of step (3) in Example 1.

[0175] The conversion rate of methacrylic acid was 60.8% and the selectivity of methyl methacrylate was 82.9%.

[0176] As can be seen from the above results, the supported esterification catalyst provided by the present application can directly convert methacrylic acid and methanol to methyl methacrylate, thereby obtaining a higher conversion rate of methacrylic acid and a higher selectivity of methyl methacrylate.

[0177] In Comparative Example 1, the content of the alumina-MCM-41 composite carrier A in the supported esterification catalyst was too high, and due to the insufficient content of the active component alkyl sulfonate on the catalyst, the active sites were insufficient during the reaction, which resulted in a low conversion rate of methacrylic acid and a low selectivity of methyl methacrylate.

[0178] In the comparative example 2, the content of the alumina-MCM-41 composite carrier A in the supported esterification catalyst is too low, and the active component alkyl sulfonate on the catalyst is not uniformly dispersed on the carrier, which results in low utilization efficiency of the active sites during the reaction, low conversion rate of methacrylic acid, and low selectivity of methyl methacrylate.

[0179] In the comparative example 3, the alumina-MCM-41 composite carrier specified in the present application is not used, but a commercially available silica is used, and the commercially available silica has an irregular pore structure, which causes the active component to be not uniformly dispersed on the surface of the carrier, resulting in low conversion rate of methacrylic acid and low selectivity of methyl methacrylate.

[0180] In the comparative example 4, the ratio of the alumina precursor to the MCM-41 all-silica mesoporous molecular sieve in the preparation process of the alumina-MCM-41 composite carrier is not within the range specified in the present application, the content of the MCM-41 all-silica mesoporous molecular sieve is too high, the particle strength of the prepared alumina-MCM-41 composite carrier is only 15.0 N, and the yield is also low. The carrier itself has an irregular shape, and the active component is not uniformly dispersed on the surface of the carrier, which results in low conversion rate of methacrylic acid and low selectivity of methyl methacrylate.

[0181] In the comparative example 5, no alumina precursor is used in the preparation process of the alumina-MCM-41 composite carrier, and only the MCM-41 all-silica mesoporous molecular sieve is used. The prepared spherical carrier has an irregular spherical degree, a non-smooth spherical surface, a particle strength of only 4.1 N, and a yield of only 64%. The supported esterification catalyst prepared by further preparing the carrier is fragile and cannot meet the requirements of industrial applications.

[0182] In the comparative example 6, the supported esterification catalyst provided in the present application is not used, but a commercially available resin material is used for the synthesis reaction of methyl methacrylate. The conversion rate of methacrylic acid and the selectivity of methyl methacrylate of the resin catalyst are lower than those of the supported esterification catalyst provided in the present application.

[0183] In the comparative example 7, the active component in the supported esterification catalyst is not selected as an alkyl sulfonate, but is selected as sodium sulfate. Due to the poor esterification catalytic performance of sodium sulfate, the conversion rate of methacrylic acid is low, and the selectivity of methyl methacrylate is low.

[0184] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed in the present application and fall within the protection scope of the present application.

Claims

1. Use of a supported esterification catalyst in a methyl methacrylate synthesis reaction, said use comprising: The reaction is carried out by simultaneously contacting methacrylic acid and methanol with a supported esterification catalyst; characterized in that the supported esterification catalyst comprises a spherical composite carrier and an alkyl sulfonate salt supported on the spherical composite carrier; the spherical composite carrier is an alumina-MCM-41 composite material, and the content of the spherical composite carrier is 45-75% by weight, the content of the alkyl sulfonate salt is 25-55% by weight, the specific surface area of the alumina-MCM-41 composite carrier is 600-780 m 2 / g, and the average particle diameter is 1.6-1.8 mm, based on the total weight of the supported esterification catalyst; the specific surface area of the MCM-41 full-silicon mesoporous molecular sieve is 900-1300 m 2 / g, the pore volume is 0.8-1.4 cm 3 / g, and the average pore size is 2-4 nm.

2. The use according to claim 1, wherein, The content of the spherical composite carrier is 50-70% by weight and the content of the alkyl sulfonate is 30-50% by weight, based on the total weight of the supported esterification catalyst.

3. The use according to claim 2, wherein, The content of the composite carrier is 53-66% by weight and the content of the alkyl sulfonate is 34-47% by weight, based on the total weight of the supported esterification catalyst.

4. The use according to claim 1, wherein, The alkyl sulfonate is a linear alkyl sulfonate and / or a branched alkyl sulfonate; And / or, the alkyl in the alkyl sulfonate is selected from one or more of heptane, decyl, dodecyl and tetradecyl; And / or, the sulfonate in the alkyl sulfonate is lanthanum sulfonate and / or cerium sulfonate.

5. The use according to claim 1, wherein, The pore volume of the alumina-MCM-41 composite carrier is 0.5-1.2 cm 3 / g, the bulk density is 0.58-0.65 g / mL, and the average particle strength is higher than 30 N.

6. The supported esterification catalyst of claim 5, wherein, The pore volume of the alumina-MCM-41 composite carrier is 0.6-1 cm 3 / g, the bulk density is 0.58-0.64 g / mL, and the average particle strength is 30-45 N.

7. Use according to claim 6, wherein, The specific surface area of the alumina-MCM-41 composite carrier is 649-752 m 2 / g, the pore volume is 0.65-0.73 cm 3 / g, the bulk density is 0.59-0.63 g / mL, the average particle diameter is 1.62-1.79 mm, and the average particle strength is 35.1-41.7 N.

8. The use according to claim 1, wherein, The preparation method of the alumina-MCM-41 composite carrier comprises: (1) contacting and mixing alumina precursor, MCM-41 full-silicon mesoporous molecular sieve, acidic aqueous solution and extrusion aid, and performing pelletizing treatment on the obtained mixture to obtain spherical precursor; (2) performing drying and calcination treatment on the spherical precursor to obtain spherical composite carrier.

9. Use according to claim 8, wherein, The alumina precursor can be selected from one or more of pseudoboehmite, aluminum hydroxide gel, aluminum sol, gibbsite or monohydrate soft aluminum. And / or, the weight ratio of the alumina precursor, the MCM-41 full-silicon mesoporous molecular sieve, the extrusion aid and the acidic aqueous solution is 1:(0.2-1):(0.02-0.5):(0.2-5).

10. Use according to claim 8, wherein, The preparation method of the MCM-41 full-silicon mesoporous molecular sieve comprises: (1) mixing cetyltrimethylammonium bromide, tetramethylammonium hydroxide and deionized water to obtain a first mixture; (2) fully mixing tetramethyl orthosilicate and isopropyl alcohol to obtain a second mixture; (3) slowly adding the second mixture into the first mixture, separating the solid product from the mother liquor after crystallization, and performing washing, drying and calcination treatment on the obtained solid product to obtain MCM-41 full-silicon mesoporous molecular sieve.

11. Use according to claim 10, wherein, The molar ratio of the amounts of tetramethylammonium hydroxide, cetyltrimethylammonium bromide, isopropyl alcohol and H2O is 1:(0.1-0.4):(0.1-0.4):(10-50).

12. The use according to any one of claims 1 to 11, wherein, The preparation method of the supported esterification catalyst comprises: (1) mixing spherical composite carrier, sodium alkyl sulfonate and deionized water to obtain mixture 1; (2) contacting and reacting aqueous solution of metal salt with mixture 1 to obtain mixture 2; (3) filtering mixture 2 to obtain solid product, and sequentially performing washing and drying treatment on the solid product to obtain supported esterification catalyst.

13. Use according to claim 12, wherein, The weight ratio of the spherical composite carrier, the sodium alkyl sulfonate and deionized water is 1:(0.1-5):(5-100); And / or, the metal salt is selected from one or more of chloride salt, sulfate salt and nitrate salt of metal.

14. Use according to claim 13, wherein, The metal is lanthanum and / or cerium.

15. The use according to claim 12, wherein, The concentration of the aqueous solution of metal salt is 0.02-1.0 mol / L.

16. The use according to claim 15, wherein, The weight ratio of the amount of the spherical composite carrier and the aqueous solution of metal salt is 1:(50-500).

17. The use according to claim 12, wherein, The aqueous solution of metal salt is contacted with the mixture 1, wherein the contacting reaction is carried out at a temperature of 40-100℃ for 0.1-20h.

18. The use according to claim 1, wherein, The reaction is carried out by simultaneously contacting methacrylic acid and methanol with the supported esterification catalyst, wherein the contacting conditions include a temperature of 40-150 DEG C, a pressure of 0.01-5.0 MPa, a mass space velocity of the methacrylic acid of 0.01-30 h -1 , and a mass space velocity of the methanol of 0.01-50 h -1 .

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