Esterification catalyst, method for preparing the same, and use thereof in the synthesis of methyl oleate

Abstract

The present application relates to the technical field of fine chemical industry, and discloses an esterification catalyst, a preparation method thereof and application of the esterification catalyst in a methyl oleate synthesis reaction.The esterification catalyst comprises a spherical carrier and an iron salt supported on the spherical carrier, the spherical carrier is a spherical alumina-MCM-48 composite carrier, and the content of the spherical carrier is 50-90 wt% and the content of the iron salt is 10-50 wt% based on the total weight of the esterification catalyst.The esterification catalyst is used in the synthesis reaction of methyl oleate, and higher conversion rate of oleic acid and selectivity of methyl oleate can be obtained.

Description

TECHNICAL FIELD

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

[0002] Methyl oleate is an important organic chemical product, which is mainly used as a surface active base material, a leather and rubber softener, a non-fluorescent mud lubricant for oil exploration, a plastic plasticizer, a water-resistant agent, a resin toughening agent, and is often used in organic synthesis. In addition, methyl oleate can also be used as an intermediate of a detergent, an emulsifier, a wetting agent and a stabilizer, and is widely used in various emulsified products, and is also used as a solvent for perfumes and a lubricant for spray products. At present, the traditional process for producing methyl oleate in industry is to use inorganic acid or organic acid (for example: concentrated sulfuric acid, concentrated hydrochloric acid or p-toluene sulfonic acid) as a catalyst to catalyze the esterification reaction of oleic acid and methanol to generate methyl oleate. The inorganic acid or organic acid catalyst has the advantage of low price, but has the disadvantages of serious environmental pollution, high requirement for equipment material, many side reactions, many by-products, and difficult separation and purification of the obtained product. In recent years, the production process of oleic acid ester in China has been continuously developed, and the production capacity of oleic acid ester 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 been widely applied in industrial production. The solid catalyst has the advantages of good stability, high selectivity, low cost and easy separation in the esterification reaction. However, the reaction speed of this kind of catalyst is slow, and the ester yield is low. The cation exchange resin has the advantages of good stability, high selectivity, low cost and easy separation in the esterification reaction. However, the cation exchange resin itself has poor heat resistance (generally suitable for esterification reactions below 150°C), 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.

[0003] Compared with the resin catalyst, the hydrogen type zeolite molecular sieve has a certain pore structure and surface acidity, which is suitable for catalyzing the esterification reaction of small molecules. However, the pore size of the zeolite molecular sieve is small (0.5-0.7 nm), which may inhibit the diffusion of macromolecular products in the reaction; and the number of acid sites on the surface of the zeolite molecular sieve is small, and the efficiency of the catalytic esterification reaction is low.

[0004] With the increasing demand for oleic acid ester, the green and environmentally friendly process for synthesizing oleic acid ester has broad prospects. For researchers, it is an important work direction in the future to develop an excellent oleic acid ester synthesis reaction catalyst, improve the reaction efficiency and inhibit the generation of by-products. SUMMARY

[0005] The present application aims to overcome the problems of excessive side reactions and serious environmental pollution caused by the homogeneous acid catalyst used in the current methyl oleate production process, and the problems of poor catalytic activity and low ester selectivity of solid acid catalyst and acidic cation exchange resin catalyst. An esterification catalyst, a preparation method thereof and an application thereof in the synthesis of methyl oleate are provided. The esterification catalyst is used in the synthesis of methyl oleate, and higher conversion rate of oleic acid and selectivity of methyl oleate can be obtained.

[0006] To achieve the above-mentioned purpose, the present application provides an esterification catalyst in a first aspect, wherein the esterification catalyst comprises a spherical carrier and an iron salt supported on the spherical carrier, the spherical carrier is a spherical alumina-MCM-48 composite carrier, and the content of the spherical carrier is 50-90% by weight and the content of the iron salt is 10-50% by weight based on the total weight of the esterification catalyst.

[0007] The present application provides a preparation method of an esterification catalyst in a second aspect, wherein the preparation method comprises: contacting a spherical alumina-MCM-48 composite carrier with an iron salt solution to react, then separating to obtain a solid product, drying and calcining the solid product to obtain the esterification catalyst.

[0008] The present application provides an esterification catalyst prepared by the method described above in a third aspect.

[0009] The present application provides an application of the esterification catalyst described above in the synthesis of methyl oleate in a fourth aspect.

[0010] Compared with the prior art, the technical scheme of the present application has the following advantages:

[0011] (1) The esterification catalyst provided by the present 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.

[0012] (2) The esterification catalyst provided by the present application is easy to obtain raw materials, the preparation method is simple, the conditions are easy to control, and the product has good repeatability.

[0013] (3) The esterification catalyst provided by the present application has mild process conditions when used in the synthesis of oleic acid ester, and has low requirements for the reaction device; the conversion rate of oleic acid is high, and the selectivity of oleic acid ester is high.

[0014] Other features and advantages of the present application will be described in detail in the following specific embodiment part. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1is a picture of the spherical alumina-MCM-48 composite support A prepared in Example 1 of the present application;

[0016] Figure 2 is a small angle XRD pattern of the spherical alumina-MCM-48 composite support A prepared in Example 1 of the present application;

[0017] Figure 3 is a wide angle XRD pattern of the spherical alumina-MCM-48 composite support A prepared in Example 1 of the present application;

[0018] Figure 4 is a pore size distribution of the spherical alumina-MCM-48 composite support A prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values claimed herein are not to be understood as being limited to the exact values recited as implicitly included within the range. Ranges can be expressed as from about one particular value to about another particular value. When such a range is expressed, the range is intended to include all values and sub-ranges between the specific values stated. When a range of values is provided, it is intended to include the end values in the range, unless the context clearly dictates otherwise. Combining ranges of values from the different ranges into new ranges is specifically intended.

[0020] As described previously, the first aspect of the present application provides an esterification catalyst, wherein the esterification catalyst comprises a spherical support and an iron salt supported on the spherical support, the spherical support is a spherical alumina-MCM-48 composite support, and the content of the spherical support is 50-90 wt%, and the content of the iron salt is 10-50 wt% based on the total weight of the esterification catalyst.

[0021] The inventors of the present application find that in the prior art, esterification catalysts for producing methyl oleate are classified into two categories: 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 resin catalysts have the advantages of high selectivity, low cost, and easy separation, but have low ester yield in the methyl oleate synthesis reaction process, and have 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. Based on this, the inventors of the present application develop a new solid catalyst system to compensate for the performance defects of the resin catalyst, and the problem is well solved.

[0022] Further, the inventors of the present application find through research that ferric chloride, ferric sulfate and ferrous sulfate are all Lewis acids, which have high activity, good selectivity and mild reaction conditions when used as esterification catalysts, and are very promising green esterification catalysts. However, such catalysts can be partially dissolved in organic solvents, resulting in difficult separation of reaction products. If a suitable carrier can be selected to disperse the iron salt catalyst well, the above problems can be solved, and the efficiency of the catalyst can be improved. If the above problems are to be solved and the catalytic performance of the esterification catalyst is to be improved, a new material with excellent structural characteristics must be selected first. MCM-48 mesoporous molecular sieve has the structural characteristics of long-range ordered pore structure, large specific surface area and large pore volume, which is beneficial to the diffusion of macromolecular reaction materials and products in esterification reactions. Although MCM-48 mesoporous molecular sieve is suitable as a carrier of esterification catalysts, it has poor adhesion and is not easy to shape. In industrial production, solid-phase esterification catalysts must be shaped before application, for example, resin catalysts are generally spherical.

[0023] Further, the inventors of the present application found in the development of the esterification catalyst that if MCM-48 mesoporous molecular sieve is mixed with an aluminum-containing material with good viscosity in a certain proportion to be acidified into a sol, and then prepared into a spherical alumina-MCM-48 composite carrier by a specific molding method, the carrier belongs to an inorganic structure and will not swell and deform in an organic solvent, and has good temperature resistance. After loading an iron salt on the spherical alumina-MCM-48 composite carrier in situ, an esterification catalyst with good mechanical strength can be obtained. The catalyst can exhibit good catalytic activity and oleate selectivity when used in the esterification of oleic acid.

[0024] According to the present application, preferably, the content of the spherical carrier is 60-80% by weight and the content of the iron salt is 20-40% by weight based on the total weight of the esterification catalyst; more preferably, the content of the spherical carrier is 63-73% by weight and the content of the iron salt is 27-37% by weight based on the total weight of the esterification catalyst; and further more preferably, the content of the spherical carrier is 63.3-72.9% by weight and the content of the iron salt is 27.1-36.7% by weight based on the total weight of the esterification catalyst. In the present application, the use of the specific content of the spherical carrier and the specific content of the iron salt can make the prepared catalyst have better catalytic activity and ester selectivity when used in the esterification of oleic acid.

[0025] According to the present application, the iron salt is a salt containing Fe 3+ and / or Fe 2+ ; preferably, the iron salt is selected from one or more of ferric chloride, ferric sulfate and ferrous sulfate.

[0026] According to the present application, the spherical alumina-MCM-48 composite carrier comprises alumina and MCM-48 all-silicon mesoporous molecular sieve; and the content of the alumina is 45-75% by weight and the content of the MCM-48 all-silicon mesoporous molecular sieve is 25-55% by weight based on the total weight of the spherical alumina-MCM-48 composite carrier; preferably, the content of the alumina is 55-66% by weight and the content of the MCM-48 all-silicon mesoporous molecular sieve is 34-45% by weight based on the total weight of the spherical composite carrier; and more preferably, the content of the alumina is 55.6-65.2% by weight and the content of the MCM-48 all-silicon mesoporous molecular sieve is 34.8-44.4% by weight based on the total weight of the spherical composite carrier.

[0027] According to the present application, the specific surface area of the spherical alumina-MCM-48 composite carrier is 400-900 m 2 / g, pore volume is 0.5-1.2 mL / g, pore size distribution is bimodal, and the most probable pore sizes corresponding to the bimodal distribution are 2-4 nm and 12-18 nm respectively, average particle diameter is 1.0-3.0 mm, and average particle strength is 20-70 N; preferably, the specific surface area of the spherical alumina-MCM-48 composite carrier is 550-700 m 2 / g, pore volume is 0.6-0.9 mL / g, pore size distribution is bimodal, and the most probable pore sizes corresponding to the bimodal distribution are 2-3 nm and 13-16 nm respectively, average particle diameter is 1.2-2.7 mm, and average particle strength is 25-60 N; more preferably, the specific surface area of the spherical alumina-MCM-48 composite carrier is 603-654 m 2 / g, pore volume is 0.67-0.75 mL / g, pore size distribution is bimodal, and the most probable pore sizes corresponding to the bimodal distribution are 2.3-2.5 nm and 13.7-14.8 nm respectively, average particle diameter is 1.74-2.44 mm, and average particle strength is 26.8-35.4 N. In the present application, the use of the spherical carrier with the specific parameters described above can make the prepared catalyst have better catalytic activity and ester selectivity when used in the esterification reaction of oleic acid.

[0028] According to the present application, the preparation method of the spherical alumina-MCM-48 composite carrier comprises:

[0029] (1) contacting and mixing an alumina precursor, MCM-48 all-silica mesoporous molecular sieve, an acidic aqueous solution and a extrusion aid, and subjecting the obtained mixture to pelletization treatment to obtain a spherical alumina-MCM-48 precursor;

[0030] (2) subjecting the spherical alumina-MCM-48 precursor to drying and calcination treatment to obtain a spherical alumina-MCM-48 composite carrier.

[0031] According to the present application, in step (1), the alumina precursor is selected from one or more of pseudoboehmite, aluminum hydroxide gel, aluminum sol, gibbsite and bayerite; in the present application, the alumina precursor can be obtained by commercial purchase or preparation, and in the present application, the alumina precursor specifically includes: bayerite powder with model number BD-BS03 (purchased from Zibo Baida Chemical Co., Ltd., Shandong, specific surface area is 269 m 2 / g, pore volume is 0.41 cm 3 / g), German original imported pseudoboehmite powder with model number SB (purchased from Beijing Asia Pacific Aohua Chemical Auxiliary Co., Ltd., specific surface area is 241 m 2 / g, pore volume is 0.53 cm 3P-DF-09-LSi (produced by Shandong Aluminum Co., Ltd., specific surface area 286 m 2 / g, pore volume 1.08 cm 3 / g) or one or more of the following: P-DF-09-LSi (produced by Shandong Aluminum Co., Ltd., specific surface area 286 m

[0032] According to the present application, the MCM-48 full-silica mesoporous molecular sieve has a specific surface area of 800-1200 m 2 / g, pore volume 0.5-0.8 cm 3 / g, pore diameter 2-3 nm; preferably, the MCM-48 full-silica mesoporous molecular sieve has a specific surface area of 1000-1150 m 2 / g, pore volume 0.6-0.7 cm 3 / g, pore diameter 2.2-2.8 nm; more preferably, the MCM-48 full-silica mesoporous molecular sieve has a specific surface area of 1089-1132 m 2 / g, pore volume 0.68-0.72 cm 3 / g, pore diameter 2.3-2.5 nm. In the present application, the MCM-48 full-silica mesoporous molecular sieve with the aforementioned specific parameters can make the prepared esterification catalyst exhibit good catalytic activity and oleate selectivity when used in the esterification reaction of oleic acid.

[0033] According to the present application, the MCM-48 mesoporous molecular sieve can be a commercially available product or a self-made sample. In the present application, preferably, the preparation method of the MCM-48 mesoporous molecular sieve comprises:

[0034] (S1) hydrolyzing a template agent, a silicon source and sodium hydroxide under hydrolysis gel-making conditions to obtain a gel mixture;

[0035] (S2) crystallizing the gel mixture under crystallization conditions, and obtaining a solid product after solid-liquid two-phase separation;

[0036] (S3) washing, drying and removing the template agent from the solid product to obtain the MCM-48 mesoporous molecular sieve.

[0037] According to the present application, the silicon source is preferably orthosilicate with a general formula of (RO)4Si, wherein R is a linear or branched alkyl group with 1-4 carbon atoms.

[0038] According to the present application, the template agent is a mixture of a quaternary ammonium cationic surfactant and a neutral amine surfactant; and the molar ratio of the quaternary ammonium cationic surfactant to the neutral amine surfactant is 1:(0.03-0.07).

[0039] According to the present application, the molar ratio of the silicon source: template agent: sodium hydroxide: water is 1: (0.1-0.2): (0.4-0.6): (50-90), preferably 1: (0.12-0.18): (0.45-0.55): (60-80).

[0040] According to the present application, the hydrolysis and gelation conditions include a temperature of 10-60℃ and a time of 0.5-10h.

[0041] According to the present application, the crystallization conditions include a temperature of 100-130℃ and a time of 12-96h.

[0042] According to the present application, the drying conditions include a temperature of 70-150℃ and a time of 3-10h.

[0043] According to the present application, the method for removing the template agent is not particularly limited and can be any conventional method, such as calcination or extraction.

[0044] According to the present application, the acidic aqueous solution can be an organic acid aqueous solution or an inorganic acid aqueous solution, preferably the acidic 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 acidic aqueous solution is nitric acid aqueous solution or citric acid aqueous solution; in the present application, the mass concentration of the acidic aqueous solution is 1-20%, preferably 2-15%.

[0045] 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.

[0046] According to the present application, the weight ratio of the alumina precursor, the MCM-48 mesoporous molecular sieve, the extrusion aid and the acidic aqueous solution is 1: (0.3-0.8): (0.02-0.5): (0.2-5); preferably the weight ratio of the alumina precursor, the MCM-48 mesoporous molecular sieve, the extrusion aid and the acidic aqueous solution is 1: (0.4-0.6): (0.05-0.2): (0.4-2).

[0047] According to the present application, in step (1), the alumina precursor, the MCM-48 all-silicon mesoporous molecular sieve, the acidic aqueous solution and the extrusion aid are contacted and mixed, and the mixing conditions include a stirring rate of 50-300r / min, a temperature of 20-60℃ and a time of 0.5-6h; preferably the stirring rate is 150-200r / min, the temperature is 20-35℃ and the time is 0.5-1h.

[0048] According to the present application, in step (2), the drying conditions include: temperature of 70-150℃, time of 3-24h; preferably, temperature of 110-120℃, time of 8-12h.

[0049] According to the present application, in step (2), the drying conditions include: temperature of 70-150℃, time of 3-24h; preferably, temperature of 110-120℃, time of 8-12h.

[0050] According to the present application, in step (1), the micro-pellet balling method includes:

[0051] (1-1) extruding the mixture into a strip, and then cutting and extruding into raw balls;

[0052] (1-2) shaping the raw balls to obtain standard round balls;

[0053] (1-3) screening the standard round balls to obtain spherical precursors.

[0054] According to a preferred embodiment of the present application, the micro-pellet balling method includes: in a kneader, uniformly mixing the alumina precursor, the MCM-48 mesoporous molecular sieve, the acidic aqueous solution, and the extrusion aid, and then transferring the mixture to a micro-ball machine to extrude a long strip with a circular cross section, and then cutting and extruding into raw balls; placing the raw balls into a micro-pellet shaper to shape them into standard round balls, and then placing the obtained product into a micro-pellet screening machine to screen out spherical precursors with suitable sizes.

[0055] According to the present application, in step (1-1), after uniformly mixing the alumina precursor, the MCM-48 mesoporous molecular sieve, the acidic aqueous solution, and the extrusion aid, the mixture is transferred to a micro-ball machine to extrude a long strip with a circular cross section, and then cutting and extruding into raw balls; wherein the extruding into a strip includes: extruding speed of 0.5-5m / min, and the circular cross section diameter of the long strip of 1.0-3.0mm; and the cutting includes: cutting speed of 100-3500 particles / minute.

[0056] According to the present application, in step (1-2), the raw balls are placed into a micro-pellet shaper to shape them into standard round balls; wherein the shaping includes: tumbling time of 0.5-10 minutes / time, tumbling times of 1-5 times, and sample cavity rotation speed of 50-1400r / min.

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

[0058] The second aspect of the present application provides a preparation method of an esterification catalyst, wherein the preparation method comprises: contacting a spherical alumina-MCM-48 composite carrier with an iron salt solution to react, then separating to obtain a solid product, and drying and calcining the solid product to obtain the esterification catalyst.

[0059] According to the present application, the iron salt solution is one or more of an aqueous solution, an ethanol solution, a methanol solution, a toluene solution and an acetone solution of an iron salt; preferably an aqueous solution or an ethanol solution.

[0060] According to the present application, the weight ratio of the spherical alumina-MCM-48 composite carrier to the iron salt solution is 1:(1-200), preferably 1:(2-50).

[0061] According to the present application, the concentration of the iron salt solution is 0.1-20%, preferably 2.0-15.0%.

[0062] According to the present application, the contacting reaction conditions of the spherical alumina-MCM-48 composite carrier and the iron salt solution include that the reaction temperature can be 20-100℃, preferably 30-80℃; and the time can be 0.5-20h, preferably 1-10h.

[0063] According to the present application, preferably, in order to achieve better mixing effect, the spherical alumina-MCM-48 composite carrier and the iron salt solution can be rapidly stirred or assisted by ultrasonic means to improve the reaction efficiency during the contacting reaction process.

[0064] According to the present application, the separation method is not particularly required and can be a method known in the art, for example: using a rotary evaporator or evaporating water by heating during stirring.

[0065] According to the present application, the drying conditions include that the drying temperature is 70-150℃, and the drying time is 2-20 hours; preferably, the drying temperature is 90-130℃, and the drying time is 4-12 hours.

[0066] According to the present application, the calcination conditions include that the calcination temperature is 200-400℃, and the calcination time is 2-10 hours; preferably, the calcination temperature is 250-360℃, and the calcination time is 5-8 hours.

[0067] The third aspect of the present application provides an esterification catalyst prepared by the method described in the preceding aspect.

[0068] The fourth aspect of the present application provides an application of the esterification catalyst described in the preceding aspect in an oleic acid methyl ester synthesis reaction.

[0069] According to the present application, the application includes that the oleic acid and the methanol are simultaneously contacted with the esterification catalyst.

[0070] In the present application, the contacting conditions of the oleic acid and the methanol with the catalyst include that the temperature of the contacting can be 40-100℃, preferably 50-80℃; the weight ratio of the catalyst: the oleic acid: the methanol is 1:(2-50):(1-10), preferably 1:(5-20):(2-5); and the reaction time can be 1-12h, preferably 2-8h.

[0071] The present application will be described in detail below through examples.

[0072] In the following examples and comparative examples:

[0073] The wide-angle XRD test of the sample was performed on an X-ray powder diffractometer of Philips X'Pert MPD type in the Netherlands, Cu Kα target, scanning range 2θ = 5-90°.

[0074] The small-angle XRD test of the sample was performed on a high-power rotating target X-ray diffractometer of BRUKER AXS D8 ADVANCE type in Germany, scanning range: 0.5-10°.

[0075] The pore structure parameter analysis of the sample was performed on an ASAP2020-M+C adsorptometer purchased from Micromeritics Company in the United States. The sample was vacuum degassed at 350℃ for 4 hours before determination, the specific surface area of the sample was calculated by BET method, and the pore volume was calculated by BJH model.

[0076] 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.

[0077] The rotary evaporator was produced by IKA Company in Germany, and the model was RV10 digital.

[0078] The drying oven was produced by Shanghai Yiheng Scientific Instrument Co., Ltd., and the model was DHG-9030A.

[0079] The muffle furnace was produced by CARBOLITE Company, and the model was CWF1100.

[0080] The kneader was FN-NH2 type produced by Tianshui Huayuan Pharmaceutical Equipment Technology Co., Ltd.; the micro-sphere forming machine was HWJ-100 type produced by Tianshui Huayuan Pharmaceutical Equipment Technology Co., Ltd.; the micro-pellet shaping machine was FN-XZXJ type produced by Tianshui Huayuan Pharmaceutical Equipment Technology Co., Ltd.; and the micro-pellet screening machine was SWP-1200 type produced by Tianshui Huayuan Pharmaceutical Equipment Technology Co., Ltd.

[0081] The reagents used in the examples and comparative examples were purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd., and the purity of the reagents was analytical pure.

[0082] Example 1

[0083] (1) Preparation of spherical alumina-MCM-48 composite support

[0084] A mixture of 23.2 g of hexadecyltrimethylammonium bromide, 0.6 g of dodecylamine, 8.1 g of sodium hydroxide and 500 ml of deionized water was stirred at 45°C for 1 hour; 82.9 g of tetraethyl orthosilicate was added dropwise to the above solution, and stirred for 1 hour; the above mixture was transferred to an autoclave, and hydrothermally crystallized at 100°C for 72 hours. After the hydrothermal crystallization was completed, the solid product was separated from the mother liquor, washed with deionized water until neutral, and dried at 110°C in air for 10 hours; then calcined at 550°C for 20 hours to obtain MCM-48 mesoporous molecular sieve.

[0085] The specific surface area of the MCM-48 mesoporous molecular sieve was 1109 m 2 / g, the pore volume was 0.7 cm 3 / g, and the pore size was 2.4 nm.

[0086] A mixture of 100 g of pseudo-boehmite powder with a model of P-DF-09-L Si, 50 g of MCM-48 mesoporous molecular sieve, 78 g of dilute nitric acid with a concentration of 5.0%, and 10 g of sesbania powder was transferred to a kneader and stirred to mix uniformly. The kneading temperature was 30°C, the rotation speed of the main shaft of the kneader was 200 r / min, and the kneading time was 1 h. The uniformly mixed raw materials were placed in the hopper of a micro-sphere making machine, a die with a pore size of 1.8 mm was selected, the extrusion speed was adjusted to 1.5 m / min, and the cutting speed was 900 particles / min, so that the raw materials were extruded into strips and then cut into small round particles. The above small round particles were placed in a micro-pellet shaping machine 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 300 r / min. The standard round raw material balls obtained after shaping were placed in a micro-pellet screening machine to screen out spherical precursors with a size of 1.8 mm. The spherical precursors were dried at 110°C for 10 h, and then calcined at 600°C for 12 h to obtain spherical alumina-MCM-48 composite support A.

[0087] The content of alumina in the spherical alumina-MCM-48 composite support A was 58.3% by weight, and the content of MCM-48 all-silica mesoporous molecular sieve was 41.7% by weight.

[0088] The structural parameters of the spherical alumina-MCM-48 composite support A are listed in Table 1.

[0089] Figure 1 is a photo of the spherical alumina-MCM-48 composite support A prepared in Example 1 of the present application. It can be seen that the support has a white round appearance, good sphericity, smooth spherical surface, and uniform particle size.

[0090] Figure 2 is the small angle XRD pattern of the spherical alumina-MCM-48 composite support A prepared in Example 1 of the present application. From Figure 2 It can be seen that the sample has a sharp strong diffraction peak and a weak but clear diffraction peak between 2θ = 2.5° to 3.5°, which correspond to (211) and (220) crystal planes, respectively. In addition, there is a group of diffraction signals at 2θ = 4.0° to 6.0°, which include diffraction peaks corresponding to (420) and (332) crystal planes. The above-mentioned diffraction signals are the characteristic diffraction peaks of MCM-48 mesoporous molecular sieve. It indicates that after the spherical composite support A is calcined at 600°C, the crystal phase of the MCM-48 mesoporous molecular sieve does not change significantly, and still maintains the typical three-dimensional cubic phase mesoporous structure.

[0091] Figure 3 is the wide angle XRD pattern of the spherical alumina-MCM-48 composite support A prepared in Example 1 of the present application. The XRD wide angle diffraction pattern of the spherical alumina-MCM-48 composite support is exactly the same as that of alumina, because the structure of the MCM-48 mesoporous molecular sieve has no diffraction signals in the wide angle part. The main x-ray diffraction angles are: 2θ = 37.1°, 39.3°, 46.1°, 60.7° and 66.6°, which are consistent with the diffraction pattern of γ-Al2O3, indicating that after the spherical composite support A is calcined at 600°C, the pseudoboehmite with model number P-DF-09-LSi presents a typical γ-Al2O3 crystal phase after dehydration. In addition, it should be noted that the XRD signals of the spherical composite support cannot be displayed in one figure, nor can they be detected by the same characterization means. Therefore, the XRD patterns given here are two, one wide angle and one small angle.

[0092] Figure 4 is the pore size distribution of the spherical alumina-MCM-48 composite support A prepared in the present application. From Figure 4 It can be seen that the pore size of the sample has a bimodal distribution, with the first most probable pore size being 2.4 nm, mainly contributed by the mesoporous molecular sieve, and the second most probable pore size being 14.0 nm, mainly contributed by alumina.

[0093] (2) Preparation of esterification catalyst

[0094] 100 g of the spherical alumina-MCM-48 composite support A, 800 g of an aqueous solution of ferric chloride with a mass concentration of 6.0%, were mixed and stirred at 60°C for 8 h. The solvent water in the system was removed using a rotary evaporator, and the solid product was dried at 100°C for 12 h and then calcined at 320°C for 6 h to obtain the esterification catalyst A.

[0095] The content of the spherical alumina-MCM-48 composite support A is 67.5% by weight and the content of the ferric chloride is 32.5% by weight, based on the total weight of the esterification catalyst A.

[0096] (3) Catalyst reaction performance evaluation

[0097] 1 gram of the esterification catalyst A, 14.1 grams of oleic acid and 3.2 grams of methanol were weighed into a 100 ml three-necked flask, a condenser tube was added, and stirring was carried out under the condition of heating reflux at 60°C for 6h. After cooling to room temperature, the product was separated by centrifugation and analyzed by Agilent 7890A gas chromatograph equipped with FFAP capillary column and hydrogen flame detector (FID), using programmed temperature and quantitative analysis with correction factor. The conversion rate of oleic acid was 98.2% and the selectivity of methyl oleate was 99.4%.

[0098] Example 2

[0099] (1) Preparation of spherical alumina-MCM-48 composite support

[0100] The MCM-48 mesoporous molecular sieve was prepared according to the same method as step (1) in Example 1.

[0101] 100g of boehmite powder with model number BD-BS03, 40g of MCM-48 mesoporous molecular sieve, 62g of 10% acetic acid aqueous solution and 5g of polyethylene glycol were mixed and transferred to a kneader for stirring and mixing uniformly. The kneading temperature was 35°C, the main shaft rotation speed of the kneader was 150r / min, and the kneading time was 1h. The uniformly mixed raw materials were placed in the hopper of a micro-sphere forming machine, a 2.5mm diameter extrusion die was selected, the extrusion speed was adjusted to 5m / min, and the cutting speed was 2000 particles / min, the raw materials were extruded into strips and then cut into small round particles. The above small round particles were placed in a micro-pellet shaping machine for shaping, and the shaping conditions were as follows: the rolling time was 0.5min / time, the rolling times was 2 times, and the sample cavity rotation speed was 500r / min. The standard round raw material balls obtained after shaping were placed in a micro-pellet screening machine to screen out spherical precursors with a size of 2.5mm. The spherical precursors were dried at 120°C for 8h and then calcined at 700°C for 6h to obtain the spherical alumina-MCM-48 composite support B.

[0102] The content of alumina in the spherical alumina-MCM-48 composite support B was 65.2% by weight, and the content of MCM-48 all-silicon mesoporous molecular sieve was 34.8% by weight.

[0103] The spherical alumina-MCM-48 composite support B was characterized, and the structure parameters are listed in Table 1.

[0104] (2) Preparation of esterification catalyst

[0105] 100 g of the spherical alumina-MCM-48 composite support B, 1860 g of an iron sulfate ethanol solution with a mass concentration of 2.0% were mixed, and stirred at 30°C for 16 h. After the reaction was completed, the stirring was stopped, and the solvent ethanol was removed using a rotary evaporator to obtain a solid product. The solid product was dried at 90°C for 8 h and calcined at 250°C for 8 h to obtain the esterification catalyst B.

[0106] The content of the spherical alumina-MCM-48 composite support B was 72.9% by weight, and the content of the iron sulfate was 27.1% by weight, based on the total weight of the esterification catalyst B.

[0107] (3) Catalyst reaction performance evaluation

[0108] The esterification reaction performance test of the catalyst B was carried out according to the method of step (3) in Example 1. The conversion rate of oleic acid was 98.0%, and the selectivity of methyl oleate was 99.2%.

[0109] Example 3

[0110] (1) Preparation of spherical alumina-MCM-48 composite support

[0111] The MCM-48 mesoporous molecular sieve was prepared according to the same method as step (1) in Example 1.

[0112] 100 g of German original pseudo-boehmite powder of type SB, 60 g of MCM-48 mesoporous molecular sieve, 80 g of a citric acid aqueous solution with a concentration of 15.0%, and 18 g of cellulose were mixed and transferred to a kneader for stirring and mixing uniformly. The kneading temperature was 20°C, the main shaft rotating speed of the kneader was 200 r / min, and the kneading time was 0.5 h. The uniformly mixed raw materials were placed in the hopper of a micro-sphere making machine, a 2.0 mm diameter extrusion die was selected, the extrusion speed was adjusted to 1 m / min, and the cutting speed was 500 particles / min, and the raw materials were extruded into strips and then cut into round small particles. The round small particles were placed in a micro-pellet shaping machine for shaping, and the shaping conditions were as follows: the rolling time was 2 minutes / time, the rolling times were 4 times, and the sample cavity rotating speed was 200 r / min. The standard round spherical raw material balls obtained after shaping were placed in a micro-pellet screening machine to screen out spherical precursors with a size of 2.0 mm. The spherical precursors were dried at 110°C for 12 h and then calcined at 550°C for 15 h to obtain the spherical alumina-MCM-48 composite support C.

[0113] The content of alumina in the spherical alumina-MCM-48 composite support C was 55.6% by weight, and the content of the MCM-48 all-silicon mesoporous molecular sieve was 44.4% by weight.

[0114] The spherical alumina-MCM-48 composite support C was characterized, and the structure parameters are shown in Table 1.

[0115] (2) Preparation of esterification catalyst

[0116] 100 g of the spherical alumina-MCM-48 composite support C and 385 g of a ferrous sulfate aqueous solution with a mass concentration of 15.0% were mixed and stirred at 80°C for 1.5 h. After the reaction was completed, the stirring was stopped and the solvent water was removed using a rotary evaporator to obtain a solid product. The solid product was dried at 130°C for 4 h and calcined at 360°C for 5 h to obtain the esterification catalyst C.

[0117] The content of the spherical alumina-MCM-48 composite support C was 63.3% by weight and the content of the ferrous sulfate was 36.7% by weight, based on the total weight of the esterification catalyst C.

[0118] (3) Evaluation of the reaction performance of the catalyst

[0119] The esterification reaction performance test of the catalyst C was performed according to the method of step (3) in Example 1. The conversion rate of oleic acid was 98.4% and the selectivity of methyl oleate was 99.1%.

[0120] Table 1

[0121]

[0122] Example 4

[0123] The esterification catalyst 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:

[0124] 100 g of the spherical alumina-MCM-48 composite support A and 525 g of an iron trichloride aqueous solution with a mass concentration of 6.0% were mixed and stirred at 60°C for 8 h. The solvent water in the system was removed using a rotary evaporator, the solid product was dried at 100°C for 12 h, and then calcined at 320°C for 6 h to obtain the esterification catalyst D.

[0125] The content of the spherical alumina-MCM-48 composite support A was 76.1% by weight and the content of the iron trichloride was 23.9% by weight, based on the total weight of the esterification catalyst D.

[0126] 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 oleic acid was 96.0% and the selectivity of methyl oleate was 98.5%.

[0127] Example 5

[0128] The esterification catalyst 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:

[0129] 100 g of the spherical alumina-MCM-48 composite support A, 833 g of an aqueous solution of ferric chloride with a mass concentration of 8.0% were mixed and stirred at 60°C for 8 h. The solvent water in the system was removed using a rotary evaporator, and the solid product was dried at 100°C for 12 h and then calcined at 320°C for 6 h to obtain the esterification catalyst E.

[0130] The content of the spherical alumina-MCM-48 composite support A was 60% by weight, and the content of ferric chloride was 40% by weight, based on the total weight of the esterification catalyst E.

[0131] The catalytic performance of the catalyst E was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of oleic acid was 95.7%, and the selectivity of methyl oleate was 98.2%.

[0132] Example 6

[0133] The esterification catalyst was prepared in the same manner as in Example 1, except that the preparation conditions of the catalyst in step (2) in Example 1 were changed, specifically:

[0134] 100 g of the spherical alumina-MCM-48 composite support A, 214 g of an aqueous solution of ferric chloride with a mass concentration of 6.0% were mixed and stirred at 60°C for 8 h. The solvent water in the system was removed using a rotary evaporator, and the solid product was dried at 100°C for 12 h and then calcined at 320°C for 6 h to obtain the esterification catalyst F.

[0135] The content of the spherical alumina-MCM-48 composite support A was 88.6% by weight, and the content of ferric chloride was 11.4% by weight, based on the total weight of the esterification catalyst F.

[0136] The catalytic performance of the catalyst F was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of oleic acid was 94.0%, and the selectivity of methyl oleate was 97.5%.

[0137] Example 7

[0138] The esterification catalyst was prepared in the same manner as in Example 1, except that the preparation conditions of the catalyst in step (2) in Example 1 were changed, specifically:

[0139] 100 g of the spherical alumina-MCM-48 composite support A, 1000 g of an aqueous solution of ferric chloride with a mass concentration of 10.0% were mixed and stirred at 60°C for 8 h. The solvent water in the system was removed using a rotary evaporator, and the solid product was dried at 100°C for 12 h and then calcined at 320°C for 6 h to obtain the esterification catalyst G.

[0140] The content of the spherical alumina-MCM-48 composite carrier A is 50% by weight and the content of the ferric chloride is 50% by weight, based on the total weight of the esterification catalyst G.

[0141] 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 oleic acid is 94.4% and the selectivity of methyl oleate is 97.6%.

[0142] Comparative Example 1

[0143] The esterification catalyst 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:

[0144] 100 g of the spherical alumina-MCM-48 composite carrier A and 130 g of a ferric chloride aqueous solution with a mass concentration of 6.0% are mixed and stirred at 60°C for 8 h. The solvent water in the system is removed using a rotary evaporator, the solid product is dried at 100°C for 12 h, and then calcined at 320°C for 6 h to obtain the esterification catalyst D1.

[0145] The content of the spherical alumina-MCM-48 composite carrier A is 92.7% by weight and the content of the ferric chloride is 7.3% by weight, based on the total weight of the esterification catalyst D1.

[0146] 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 oleic acid is 70.8% and the selectivity of methyl oleate is 92.0%.

[0147] Comparative Example 2

[0148] The esterification catalyst 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:

[0149] 100 g of the spherical alumina-MCM-48 composite carrier A and 1087 g of a ferric chloride aqueous solution with a mass concentration of 15.0% are mixed and stirred at 60°C for 8 h. The solvent water in the system is removed using a rotary evaporator, the solid product is dried at 100°C for 12 h, and then calcined at 320°C for 6 h to obtain the esterification catalyst D2.

[0150] The content of the spherical alumina-MCM-48 composite carrier A is 38% by weight and the content of the ferric chloride is 62% by weight, based on the total weight of the esterification catalyst D2.

[0151] The catalytic performance of the catalyst D2 is tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of oleic acid is 75.3% and the selectivity of methyl oleate is 93.7%.

[0152] Comparative Example 3

[0153] The esterification catalyst was prepared in the same manner as in Example 1, except that step (1) in Example 1 was omitted, and the spherical alumina-MCM-48 composite support A in step (2) in Example 1 was replaced by commercially available silica (purchased from Qingdao Hailang Silica Gel Dryer Factory, specific surface area 329 m 2 / g, average particle diameter 1.5 mm), to obtain catalyst D3.

[0154] The content of the commercially available silica was 67.5% by weight, and the content of the ferric chloride was 32.5% by weight, based on the total weight of the catalyst D3.

[0155] 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 oleic acid was 89.1%, and the selectivity of methyl oleate was 95.5%.

[0156] Comparative Example 4

[0157] The esterification catalyst was prepared in the same manner as in Example 1, except that step (1) in Example 1 was omitted, and 100 g of the spherical alumina-MCM-48 composite support A in step (2) in Example 1 was replaced by 143 g of pseudo-boehmite with a model number of P-DF-09-L Si, to obtain catalyst D4.

[0158] The content of the alumina was 67.5% by weight, and the content of the ferric chloride was 32.5% by weight, based on the total weight of the catalyst D4.

[0159] The catalytic performance of the catalyst D4 was tested according to the esterification reaction performance evaluation method of step (3) in Example 1. The conversion rate of oleic acid was 90.8%, and the selectivity of methyl oleate was 96.0%.

[0160] Comparative Example 5

[0161] The esterification catalyst was prepared in the same manner as in Example 1, except that in step (1), 70 g of pseudo-boehmite powder with a model number of P-DF-09-L Si and 98 g of MCM-48 mesoporous molecular sieve were used, to obtain catalyst D5; that is, the content of the alumina was 41.7% by weight, and the content of the MCM-48 all-silica mesoporous molecular sieve was 58.3% by weight, based on the total weight of the spherical alumina-MCM-48 composite support.

[0162] The content of the spherical support was 67.5% by weight, and the content of the ferric chloride was 32.5% by weight, based on the total weight of the catalyst D5.

[0163] The catalytic performance of catalyst D5 was tested according to the performance evaluation method of the esterification reaction of step (3) in Example 1. The conversion rate of oleic acid was 92.7%, and the selectivity of methyl oleate was 96.5%.

[0164] As can be seen from the above results, the esterification catalyst provided by the present application can directly convert oleic acid and methanol to generate methyl oleate, and a higher conversion rate of oleic acid and selectivity of methyl oleate are obtained.

[0165] In Comparative Example 1, the content of the spherical alumina-MCM-48 composite carrier A is too high, and the content of the active component iron salt on the catalyst is too low, which leads to a low conversion rate of oleic acid and a low selectivity of methyl oleate due to insufficient active sites during the reaction.

[0166] In Comparative Example 2, the content of the spherical alumina-MCM-48 composite carrier A is too low, and the content of the active component iron salt on the catalyst is too high, which leads to a low conversion rate of oleic acid and a low selectivity of methyl oleate due to uneven dispersion of the active component on the carrier and the fact that part of the active centers cannot play a catalytic role during the reaction.

[0167] In Comparative Example 3, the spherical carrier specified in the present application is not used, but a commercially available silica is used, which leads to a low conversion rate of oleic acid and a low selectivity of methyl oleate due to the irregular pore structure of the commercially available silica and uneven dispersion of the active component on the carrier surface.

[0168] In Comparative Example 4, the spherical carrier specified in the present application is not used, but a single alumina carrier is used, which leads to a low conversion rate of oleic acid and a low selectivity of methyl oleate due to uneven pore size distribution of the alumina, which is not conducive to the dispersion of the active component on the carrier surface and the diffusion of raw materials and products during the reaction.

[0169] In Comparative Example 5, the weight ratio of the content of alumina and MCM-48 mesoporous molecular sieve in the spherical carrier is 1:2, and the content of MCM-48 mesoporous molecular sieve is too high, which leads to a low conversion rate of oleic acid and a low selectivity of methyl oleate due to the fact that the proportion of MCM-48 mesoporous molecular sieve in the spherical carrier is not within the scope of the claims, the prepared catalyst has poor strength and uneven surface, the active component is poorly dispersed, and further leads to a low conversion rate of oleic acid and a low selectivity of methyl oleate.

[0170] 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, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. Use of an esterification catalyst in the synthesis of methyl oleate, wherein the catalyst comprises a mixture of a solid acid catalyst and a base catalyst. The application comprises contacting oleic acid, methanol and an esterification catalyst, characterized in that the esterification catalyst comprises a spherical carrier and an iron salt supported on the spherical carrier, the spherical carrier is a spherical alumina-MCM-48 composite carrier, and the content of the spherical carrier is 50-90% by weight and the content of the iron salt is 10-50% by weight based on the total weight of the esterification catalyst; The spherical alumina-MCM-48 composite carrier comprises alumina and MCM-48 all-silica mesoporous molecular sieve, and the content of the alumina is 45-75% by weight and the content of the MCM-48 all-silica mesoporous molecular sieve is 25-55% by weight based on the total weight of the spherical alumina-MCM-48 composite carrier; The specific surface area of the spherical alumina-MCM-48 composite carrier is 400-900 m 2 / g, the pore volume is 0.5-1.2 mL / g, the pore size distribution is bimodal, the most probable pore sizes corresponding to the bimodal distribution are 2-4 nm and 12-18 nm respectively, the average particle diameter is 1.0-3.0 mm, and the average particle strength is 20-70 N.

2. The use according to claim 1, wherein, The content of the spherical carrier is 60-80% by weight and the content of the iron salt is 20-40% by weight based on the total weight of the esterification catalyst.

3. Use according to claim 2, wherein, The content of the spherical carrier is 63-73% by weight and the content of the iron salt is 27-37% by weight based on the total weight of the esterification catalyst.

4. The use according to any one of claims 1 to 3, wherein The iron salt is a salt containing Fe 3+ or / and Fe 2+ .

5. Use according to claim 4, wherein, The iron salt is selected from one or more of ferric chloride, ferric sulfate and ferrous sulfate.

6. The use according to claim 1, wherein, The content of the alumina is 55-66% by weight and the content of the MCM-48 all-silica mesoporous molecular sieve is 34-45% by weight based on the total weight of the spherical alumina-MCM-48 composite carrier.

7. The use according to claim 1 or 6, wherein, The preparation method of the spherical alumina-MCM-48 composite carrier comprises: (1) mixing an alumina precursor, MCM-48 all-silica mesoporous molecular sieve, an acidic aqueous solution and a extrusion aid to obtain a mixture, and performing micro-pelletizing treatment on the mixture to obtain a spherical alumina-MCM-48 precursor; (2) drying and calcining the spherical alumina-MCM-48 precursor to obtain a spherical alumina-MCM-48 composite carrier.

8. Use according to claim 7, wherein, In step (1), the alumina precursor is selected from one or more of pseudoboehmite, aluminum hydroxide gel, aluminum sol, gibbsite and bayerite; and / or the MCM-48 all-silica mesoporous molecular sieve has a specific surface area of 800-1200 m 2 / g, and a pore volume of 0.5-0.8 cm 3 / g, and a pore diameter of 2-3 nm; And / or, the weight ratio of the alumina precursor, the MCM-48 all-silica mesoporous molecular sieve, the extrusion aid and the acidic aqueous solution is 1:(0.3-0.8):(0.02-0.5):(0.2-5).

9. Use according to claim 7, wherein, The preparation method of the MCM-48 all-silica mesoporous molecular sieve comprises: (S1) hydrolyzing a template agent, a silicon source and sodium hydroxide under hydrolysis gel preparation conditions to obtain a gel mixture; (S2) crystallizing the gel mixture under crystallization conditions, and obtaining a solid product after solid-liquid two-phase separation; (S3) washing, drying and removing the template agent from the solid product to obtain MCM-48 all-silica mesoporous molecular sieve.

10. Use according to claim 9, wherein, The template agent is a mixture of quaternary ammonium cationic surfactant and neutral amine surfactant; and the molar ratio of the amount of the quaternary ammonium cationic surfactant to the amount of the neutral amine surfactant is 1:(0.03-0.07). And / or, the molar ratio of the silicon source, the template agent, sodium hydroxide and water is 1: (0.1-0.2): (0.4-0.6): (50-90); And / or, the hydrolysis gel preparation condition includes: the temperature is 10-60℃, and the time is 0.5-10h.

11. The use according to claim 1, wherein, The preparation method of the esterification catalyst includes: contacting a spherical alumina-MCM-48 composite carrier with an iron salt solution to react, then separating to obtain a solid product, drying and calcining the solid product to obtain the esterification catalyst.

12. Use according to claim 11, wherein, The iron salt solution is one or more of an aqueous solution, an ethanol solution, a methanol solution, a toluene solution and an acetone solution of the iron salt; And / or, the weight ratio of the spherical alumina-MCM-48 composite carrier to the iron salt solution is 1: (1-200); And / or, the concentration of the iron salt solution is 0.1-20%; And / or, the contacting of the spherical alumina-MCM-48 composite carrier with the iron salt solution includes: the temperature is 20-100℃, and the time is 0.5-20h. And / or, the drying and calcining of the solid product includes: the temperature is 200-400℃, and the time is 2-10h.

13. The use according to claim 1, wherein, The contacting of the oleic acid, the methanol and the esterification catalyst includes: the temperature is 40-100℃, and the time is 1-12h; And / or, the weight ratio of the esterification catalyst, the oleic acid and the methanol is 1: (2-50): (1-10).

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