Solid acid catalyst as well as preparation method and application thereof

Abstract

The invention provides a solid acid catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: a reaction step: mixing aluminum hydroxide, silica sol and a template agent with water to obtain mixed slurry; adding a phosphoric acid solution into the mixed slurry for first reaction to obtain first slurry; a modification step: adding phosphate into the first slurry for modification to obtain second slurry; separating the second slurry, and washing and drying an obtained solid substance to obtain a solid acid catalyst precursor; and sintering: roasting the solid acid catalyst precursor to obtain the solid acid catalyst. The solid acid catalyst prepared by the method not only has good catalytic selectivity on products, but also has good cycle life. The method is used for preparing 2, 6-di-tert-butyl p-methylphenol by taking p-methylphenol and isobutene as raw materials; or the method is used for preparing 2, 6-di-tert-butyl m-methylphenol by taking m-methylphenol and isobutene as raw materials, and the product yield can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a solid acid catalyst, a preparation method and an application thereof. Background Art

[0002] 2,6-Di-tert-Butyl-4-methylphenol (BHT), a highly effective antioxidant, is widely used in a variety of applications, including food preservation, pharmaceutical stabilization, and polymer anti-aging, to protect these materials from oxidative damage and extend their lifespan. However, BHT synthesis technology has long faced multiple challenges, which have hindered the pace and efficiency of its large-scale industrial production.

[0003] Traditional methods for synthesizing 2,6-di-tert-butyl-4-methylphenol involve reacting p-methylphenol with isobutylene in the presence of an acidic catalyst, such as sulfonic acid or sulfuric acid. For example, Chinese patent CN1215042A utilizes sulfonic acid or sulfuric acid as a catalyst, successfully increasing the 2,6-di-tert-butyl-4-methylphenol content to 93.5%, seemingly resolving some product quality issues. However, further investigation revealed that the use of these strong acid catalysts presents a series of challenging subsequent processing challenges.

[0004] First, there's the issue of catalyst corrosion. Strong acidic catalysts like sulfuric acid are extremely corrosive to reactors and other equipment during the reaction. Long-term use significantly shortens equipment lifespan, increases the frequency of maintenance and upgrades, and directly drives up production costs. Second, wastewater treatment is difficult. After using the acidic catalyst, excess acid must be neutralized through water washing, generating large amounts of acidic wastewater, which negatively impacts the environment. Furthermore, wastewater treatment is costly and labor-intensive, increasing the complexity of subsequent treatment. Furthermore, low product selectivity limits yield and quality. While traditional catalysts can initiate the reaction, they often fail to precisely direct the reaction pathway, leading to the formation of byproducts that reduce BHT selectivity and impact the purity and yield of the final product. This issue has become increasingly pressing given the growing demand for high-purity BHT. Finally, the overall cost is high. Considering catalyst wear, equipment corrosion repair costs, wastewater treatment costs, and product losses due to low reaction selectivity, traditional synthesis routes using acidic catalysts are clearly uneconomical and inconsistent with the principles of green chemistry, limiting BHT's market competitiveness and the expansion of its applications.

[0005] In summary, while traditional BHT synthesis technology has met product requirements to a certain extent, it has significant shortcomings in terms of environmental friendliness and economic benefits. Therefore, there is an urgent need to explore new synthesis pathways, especially to find more gentle, environmentally friendly, and efficient catalyst systems, in order to fundamentally overcome the above technical bottlenecks and promote the green industrial production of BHT. Summary of the Invention

[0006] The main purpose of the present invention is to provide a solid acid catalyst and a preparation method and application thereof, so as to solve the problems existing in the prior art in the process of synthesizing 2,6-di-tert-butyl-p-methylphenol, such as low product selectivity, inability to recycle the catalyst, difficulty in treating the three wastes generated in the synthesis process, and serious pollution. The purpose is to develop a new catalyst to further improve the production efficiency of 2,6-di-tert-butyl-p-methylphenol and reduce its production cost.

[0007] The invention provides a preparation method of a solid acid catalyst, which comprises the following steps: a reaction step of mixing aluminum hydroxide, silica sol and a template agent with water to obtain a mixed slurry; adding a phosphoric acid solution to the mixed slurry for a first reaction to obtain a first slurry; a modification step of adding phosphate to the first slurry for modification to obtain a second slurry; separating the second slurry, washing and drying the obtained solid matter to obtain a solid acid catalyst precursor; and a sintering step of calcining the solid acid catalyst precursor to obtain a solid acid catalyst.

[0008] Furthermore, the weight ratio of aluminum hydroxide, silica sol and template is 1:(0.2-1):(0.013-0.027); preferably, the weight ratio of aluminum hydroxide, silica sol and template is 1:(0.4-0.6):(0.013-0.027).

[0009] Furthermore, the mass concentration of the phosphoric acid solution is 50-85%; preferably, the mass concentration of the phosphoric acid solution is 75-85%; preferably, the amount of phosphoric acid solution added is 5-7 times the weight of the aluminum hydroxide; more preferably, the amount of phosphoric acid solution added is 5-6.2 times the weight of the aluminum hydroxide; preferably, the amount of phosphate added is 16.5-50% of the weight of the aluminum hydroxide; more preferably, the amount of phosphate added is 33.3-50% of the weight of the aluminum hydroxide; preferably, the aluminum hydroxide is added in the form of an aqueous solution, and the mass concentration of the aluminum hydroxide aqueous solution is 20-40%; preferably, the mass concentration of the silica sol is 25-30%.

[0010] Further, the phosphate is an alkali metal phosphate and / or an ammonium phosphate; preferably, the phosphate is an alkali metal phosphate; preferably, the alkali metal phosphate is one or more of potassium phosphate, sodium phosphate, potassium hydrogen phosphate and potassium dihydrogen phosphate; and / or, the ammonium phosphate is one or more of ammonium phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate; preferably, the alkali metal phosphate is potassium phosphate; preferably, the template is one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium bicarbonate and hexadecyltrimethylammonium bromide; preferably, the template is hexadecyltrimethylammonium bromide; preferably, in the reaction step, the weight ratio of water to aluminum hydroxide is (3.3-6.6):1; preferably, in the reaction step, the weight ratio of water to aluminum hydroxide is (3.3-5):1.

[0011] Furthermore, the calcination includes: a solid acid catalyst precursor is subjected to a first calcination to obtain a first calcined product; the first calcined product is molded and then subjected to a second calcination to obtain a solid acid catalyst; preferably, the first calcined product is molded using an extruder; preferably, the diameter of the first calcined product after molding is 3 to 6 mm; preferably, the first calcination temperature is 400 to 500°C and the time is 2 to 6 hours; preferably, the second calcination temperature is 500 to 600°C and the time is 2 to 6 hours; preferably, the drying temperature is 70 to 120°C and the time is 3 to 6 hours; preferably, the process of mixing aluminum hydroxide, silica sol and template with water includes: mixing aluminum hydroxide and water at a first temperature, and then adding silica sol and template in sequence to obtain a mixed slurry; preferably, the first temperature is 80 to 100°C; preferably, after adding phosphate to the first slurry, the mixed slurry is subjected to a first mixing for modification; preferably, the first mixing time is 6 to 10 hours.

[0012] According to the second aspect of the present invention, a solid acid catalyst is further provided. The solid acid catalyst is prepared by the above preparation method.

[0013] According to a third aspect of the present invention, there is also provided an application of the above-mentioned solid acid catalyst, wherein the solid acid catalyst is used to catalyze the reaction of methylphenol and isobutylene to prepare 2,6-di-tert-butylmethylphenol; wherein the methylphenol is p-methylphenol and / or m-methylphenol, and the 2,6-di-tert-butylmethylphenol is 2,6-di-tert-butyl-p-methylphenol and / or 2,6-di-tert-butyl-m-methylphenol.

[0014] According to a fourth aspect of the present invention, a method for preparing 2,6-di-tert-butylmethylphenol is also provided, wherein the 2,6-di-tert-butylmethylphenol is 2,6-di-tert-butyl-p-methylphenol and / or 2,6-di-tert-butyl-m-methylphenol, and the preparation method comprises the following steps: respectively passing methylphenol and isobutylene into a preheating section of a fixed bed reactor for preheating; the methylphenol is p-methylphenol and / or m-methylphenol; mixing the preheated methylphenol and isobutylene and passing the mixture into a reaction section of the fixed bed reactor to carry out a second reaction to obtain a second reaction solution; wherein the reaction section is filled with the above-mentioned solid acid catalyst; separating the second reaction solution to obtain 2,6-di-tert-butylmethylphenol; the 2,6-di-tert-butylmethylphenol is 2,6-di-tert-butyl-p-methylphenol and / or 2,6-di-tert-butyl-m-methylphenol.

[0015] Furthermore, the molar ratio of methylphenol to isobutylene is 1:(2.5-3); preferably, the molar ratio of methylphenol to isobutylene is 1:(2.5-2.8); preferably, the temperature of the preheating section is 240-260°C; preferably, the pressure of the reaction section is 0.1-0.11 MPa; preferably, the reaction section includes a first reaction section and a second reaction section connected in sequence, and the temperature of the first reaction section is lower than the temperature of the second reaction section; preferably, when the inner diameters of the reaction sections of the fixed bed reactor are the same, the length ratio of the first reaction section to the second reaction section is (0.5-1):1; preferably, the temperature of the first reaction section is 240-260°C, and the temperature of the second reaction section is 260-280°C; more preferably, the temperature of the first reaction section is 250-260°C, and the temperature of the second reaction section is 270-280°C; preferably, the mass space velocity of the reaction section of the fixed bed reactor after the methylphenol and isobutylene are mixed is 0.9-1.5h -1 .

[0016] Furthermore, the process of separating the second reaction solution includes: first subjecting the second reaction liquid to a first separation to obtain a crude 2,6-di-tert-butylmethylphenol, and subjecting the crude 2,6-di-tert-butylmethylphenol to a second separation to obtain 2,6-di-tert-butylmethylphenol; preferably, the first separation includes rectification separation and distillation separation performed in sequence; preferably, the second separation is crystallization separation; preferably, the crystallization separation includes: melting the crude 2,6-di-tert-butylmethylphenol, and then subjecting it to a cooling step to obtain 2,6-di-tert-butylmethylphenol; preferably, the melting temperature is 70-71°C; preferably, the cooling procedure includes: cooling at a cooling rate of 2-5°C / h for 2-5h; more preferably, the cooling procedure includes: cooling at a cooling rate of 2°C / h for 4-5h.

[0017] The present invention provides a method for preparing a solid acid catalyst, comprising the following steps: a reaction step of mixing aluminum hydroxide, silica sol, and a template with water to obtain a mixed slurry; adding a phosphoric acid solution to the mixed slurry for a first reaction to obtain a first slurry; a modification step of adding a phosphate to the first slurry for modification to obtain a second slurry; separating the second slurry, washing, and drying the resulting solid material to obtain a solid acid catalyst precursor; and a sintering step of calcining the solid acid catalyst precursor to obtain a solid acid catalyst. The solid acid catalyst prepared using the preparation method of the present invention not only has good catalytic selectivity for the product but also has a long cycle life. It can be used to prepare 2,6-di-tert-butyl-p-methylphenol using p-methylphenol and isobutylene as raw materials; or to prepare 2,6-di-tert-butyl-m-methylphenol using m-methylphenol and isobutylene as raw materials, effectively improving the product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 The 2,6-di-tert-butyl-p-methylphenol prepared according to Example 1 of the present invention is shown. 13 C NMR spectrum. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] As described in the background technology section, the traditional synthesis method of 2,6-di-tert-butyl-p-methylphenol utilizes p-methylphenol and isobutylene to react in the presence of an acidic catalyst, such as sulfonic acid or sulfuric acid. However, these strong acid catalysts bring a series of difficult subsequent processing problems. For example, the selectivity of the 2,6-di-tert-butyl-p-methylphenol product is low, the catalyst cannot be recycled, and the three wastes generated during the synthesis process are difficult to treat and cause serious pollution. These factors not only do not conform to the concept of green industrial production, but also further increase the production cost of 2,6-di-tert-butyl-p-methylphenol.

[0022] In order to solve the above problems, the present invention provides a preparation method of a solid acid catalyst, which comprises the following steps: a reaction step: mixing aluminum hydroxide, silica sol and a template with water to obtain a mixed slurry; adding a phosphoric acid solution to the mixed slurry for a first reaction to obtain a first slurry; a modification step: adding phosphate to the first slurry for modification to obtain a second slurry; separating the second slurry, washing and drying the obtained solid matter to obtain a solid acid catalyst precursor; and a sintering step: calcining the solid acid catalyst precursor to obtain a solid acid catalyst.

[0023] In the preparation method of the solid acid catalyst provided by the present invention, aluminum hydroxide, silica sol and a template are first mixed with water to form a mixed slurry, and a phosphoric acid solution is added to the mixed slurry to carry out a first reaction to obtain a first slurry. In the above process, aluminum hydroxide serves as an aluminum source and silica sol serves as a silicon source. The two act together with the added phosphoric acid solution to jointly construct a solid acid catalyst skeleton under the action of the template. Secondly, after adding phosphate to the first slurry to further modify the solid acid catalyst skeleton, the obtained second slurry is separated, and the separated solid material is washed and dried to obtain a solid acid catalyst precursor. The above operation can further modify the constructed solid acid catalyst skeleton to obtain a solid acid catalyst precursor. This operation step is conducive to making the prepared solid acid catalyst have better catalytic performance and service life. Finally, the solid acid catalyst precursor is calcined to obtain a solid acid catalyst; the sintering step can not only improve the mechanical strength of the solid acid catalyst, thereby further improving its service life, but also make the catalytic performance of the solid acid catalyst finally prepared more stable, which is conducive to further improving the selectivity of the target product. The solid acid catalyst prepared using the above preparation method not only has good catalytic selectivity for the product but also has a long cycle life. Using it to prepare 2,6-di-tert-butyl-p-methylphenol from p-methylphenol and isobutylene as raw materials, or using it to prepare 2,6-di-tert-butyl-m-methylphenol from m-methylphenol and isobutylene as raw materials, can effectively improve product yield.

[0024] Specifically, in the above-mentioned method for preparing a solid acid catalyst, aluminum hydroxide in the reaction raw materials serves as an aluminum source, providing the aluminum element in the catalyst. This plays a key role in constructing acidic centers within the catalyst framework, which is particularly important for catalyzing alkylation reactions. Silica sol, as a silicon source, reacts with aluminum hydroxide to form a SiO2-Al2O3 complex. Its unique structural properties provide a foundation for the formation of catalytically active sites and further enhance the stability of the catalyst. The combination of aluminum hydroxide and the active ingredients in the silica sol forms a solid acid catalyst framework with both high porosity and stability, creating favorable conditions for subsequent phosphoric acid modification and pore formation with a template. The template acts as a pore-forming agent during the catalyst synthesis process, embedding itself into the developing catalyst framework structure to create microporous channels suitable for the entry and exit of reactants and products. The presence of these micropores greatly increases the specific surface area of the catalyst, providing more active sites for reactants, promoting the effective adsorption and reaction of reactants on the catalyst surface, and improving the reaction rate and conversion rate. Furthermore, the template agent helps the catalyst maintain an open pore structure during the reaction, preventing coking and clogging of the pores. This effectively exposes the catalyst's active sites, ensuring high catalyst activity throughout the entire reaction cycle, and effectively improving the reaction's selectivity and catalyst life. Furthermore, the addition of phosphoric acid not only increases the acidity of the molecular sieve catalyst surface but also adjusts the distribution of acidic sites, making more active sites suitable for the disubstitution reaction between isobutylene and p- or m-methylphenol. This optimization of acidity and site distribution significantly promotes the primary reaction, reduces side reactions, and thus increases product yield and selectivity.

[0025] Furthermore, the addition of phosphate can further modify the acidic sites on the catalyst surface, making it more suitable for specific types of alkylation reactions and enhancing the catalyst's ability to direct the formation of the target product. The introduction of phosphate helps balance the excessive acidity caused by phosphoric acid modification, preventing overactivation of the catalyst that can lead to increased side reactions, thereby ensuring high catalyst activity while maintaining excellent selectivity and stability. Phosphate modification not only enables the efficient synthesis of products like BHT but also improves the stability of the solid acid catalyst, extending its service life, and increasing production efficiency while further reducing the production cost of target products like BHT.

[0026] In summary, the solid acid catalyst prepared using the above preparation method not only exhibits excellent catalytic selectivity but also a long cycle life. Using it in the preparation of 2,6-di-tert-butyl-p-methylphenol from p-methylphenol and isobutylene, or in the preparation of 2,6-di-tert-butyl-m-methylphenol from m-methylphenol and isobutylene, effectively improves product yield. The catalyst's recyclability and improved product selectivity contribute to lowering production costs.

[0027] In a preferred embodiment, the weight ratio of aluminum hydroxide, silica sol and template is 1: (0.2-1): (0.013-0.027); by controlling the weight of aluminum hydroxide, silica sol and template within the above range, the pore structure of the prepared solid acid catalyst can be improved, which can further extend the service life of the catalyst while further improving the catalytic performance and selectivity of the catalyst and increasing the product yield. Preferably, the weight ratio of aluminum hydroxide, silica sol and template is 1: (0.4-0.6): (0.013-0.027). The above effect is better when the weight ratio of the three is controlled within the above preferred range. It should be further explained here that in the above weight ratio, the weight of silica sol is calculated based on its effective ingredient with reference to its corresponding mass concentration.

[0028] In a preferred embodiment, the mass concentration of the phosphoric acid solution is 50-85%; preferably, the amount of phosphoric acid solution added is 5-7 times the weight of the aluminum hydroxide. Aluminum hydroxide, silica sol, and the added phosphoric acid solution work together to construct a solid acid catalyst skeleton under the action of the template. Controlling the mass concentration of the phosphoric acid solution and the amount added within the above range can further increase the active sites of the constructed solid acid catalyst skeleton, giving the solid acid catalyst a better pore structure and service life. Preferably, the mass concentration of the phosphoric acid solution is 75-85%; more preferably, the amount of phosphoric acid solution added is 5-6.2 times the weight of the aluminum hydroxide. When the mass concentration of the phosphoric acid solution and the amount added are within the above preferred range, the above effect is better.

[0029] Preferably, the amount of phosphate added is 16.5-50% by weight of the aluminum hydroxide. The addition of phosphate can further modify the acidic sites on the catalyst surface, making it more suitable for specific types of alkylation reactions and enhancing the catalyst's ability to direct the formation of the target product. Controlling the phosphate addition amount within the above range can further improve the selectivity of the solid acid catalyst and further extend its catalytic life. More preferably, the phosphate addition amount is 33.3-50% by weight of the aluminum hydroxide. Under these conditions, the catalytic performance and catalytic life of the solid acid catalyst are even better. Preferably, the aluminum hydroxide is added as an aqueous solution with a mass concentration of 20-40%; preferably, the silica sol has a mass concentration of 25-30%. Adding the aluminum hydroxide as an aqueous solution and controlling its mass concentration within the above range can ensure more uniform mixing of the first slurry. Controlling the silica sol mass concentration within the above range can further improve the miscibility of the first slurry. Those skilled in the art will understand that during experiments, the relative addition ratios of the aluminum hydroxide aqueous solution and silica sol were calculated based on their corresponding mass concentrations and their active ingredients.

[0030] In a preferred embodiment, the phosphate is an alkali metal phosphate and / or ammonium phosphate; preferably, the phosphate is an alkali metal phosphate. The use of alkali metal phosphates and phosphates can better regulate the active sites in the solid acid catalyst. Among them, the alkali metal phosphate has a better effect on regulating the performance of the solid acid catalyst. This may be because the phosphate group in the phosphate can form a coordination bond with the hydroxyl group or metal center on the catalyst surface, changing the charge distribution on the surface, thereby adjusting the strength and distribution of the acidic site. The alkali metal ions (such as K + 、Na +) can also affect the properties of the acidic sites through electrostatic interaction, making them more selective for reactions such as alkylation and isomerization. By way of example but not limitation, the alkali metal phosphate is one or more of potassium phosphate, sodium phosphate, potassium hydrogen phosphate and potassium dihydrogen phosphate; and / or the ammonium phosphate is one or more of ammonium phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate. The solid acid catalysts prepared from the above alkali metal phosphates or ammonium phosphates have good catalytic performance and a long catalytic life. Preferably, the alkali metal phosphate is potassium phosphate; the solid acid catalyst prepared using potassium phosphate has better catalytic performance. Preferably, the template agent is one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium bicarbonate and hexadecyltrimethylammonium bromide; preferably, the template agent is hexadecyltrimethylammonium bromide; the solid acid catalyst prepared using the above types of template agents has better performance. Preferably, in the reaction step, the weight ratio of water to aluminum hydroxide is (3.3 to 6.6):1. Controlling the weight ratio of water to aluminum hydroxide within the above range can better mix the various components in the first slurry. Preferably, in the reaction step, the weight ratio of water to aluminum hydroxide is (3.3-5):1.

[0031] In a preferred embodiment, the calcination includes: subjecting the solid acid catalyst precursor to a first calcination to obtain a first calcined product; shaping the first calcined product, and then subjecting it to a second calcination to obtain a solid acid catalyst. During the above calcination process, the first calcination can remove the moisture therein to obtain a first calcined product with good formability. After the first calcined product is shaped, it is subjected to a second calcination to obtain a solid acid catalyst. Preferably, an extruder is used to perform a shaping operation on the first calcined product; preferably, the diameter of the first calcined product after shaping is 3 to 6 mm. Using an extruder to perform a shaping operation on the first calcined product is more convenient and quick. In addition, controlling the diameter of the first calcined product after shaping within the above range can not only make the prepared solid acid catalyst have better mechanical strength, but also better control the calcination time, thereby improving the preparation efficiency of the solid acid catalyst.

[0032] Preferably, the first calcination temperature is 400-500°C for 2-6 hours; preferably, the second calcination temperature is 500-600°C for 2-6 hours; preferably, the drying temperature is 70-120°C for 3-6 hours. Controlling the temperature and time during the drying and calcination processes within the above ranges can improve the mechanical strength of the prepared solid acid catalyst, further improving the service life of the solid acid catalyst. Preferably, the process of mixing aluminum hydroxide, silica sol, and a template with water comprises: mixing aluminum hydroxide with water at a first temperature, then sequentially adding silica sol and a template to form a mixed slurry; preferably, the first temperature is 80-100°C; preferably, after adding phosphate to the first slurry, the mixed slurry is subjected to a first mixing step for modification; preferably, the first mixing step lasts for 6-10 hours. Mixing aluminum hydroxide, silica sol, and a template with water according to the above conditions can achieve better mixing. It should be further noted that the temperature for the first reaction and the temperature for the modification reaction by adding phosphate is 80-100° C. Preferably, the temperature for the first reaction and the temperature for the modification reaction by adding phosphate are consistent with the temperature at which the aluminum hydroxide, silica sol, and template are mixed with water.

[0033] According to another aspect of the present invention, the present application further provides the above-mentioned solid acid catalyst, which is prepared by the above-mentioned preparation method of the solid acid catalyst.

[0034] According to a third aspect of the present invention, the present application further provides an application of the above-mentioned solid acid catalyst, wherein the solid acid catalyst is used to catalyze the reaction of methylphenol and isobutylene to prepare 2,6-di-tert-butylmethylphenol; wherein the methylphenol is p-methylphenol and / or m-methylphenol, and the 2,6-di-tert-butylmethylphenol is 2,6-di-tert-butyl-p-methylphenol and / or 2,6-di-tert-butyl-m-methylphenol. Using the above-mentioned solid acid catalyst to prepare 2,6-di-tert-butyl-p-methylphenol using p-methylphenol and isobutylene as raw materials, or using the above-mentioned solid acid catalyst to prepare 2,6-di-tert-butyl-m-methylphenol using m-methylphenol and isobutylene as raw materials, both can make the prepared products have a better yield.

[0035] According to a fourth aspect of the present invention, the present application further provides a method for preparing 2,6-di-tert-butylmethylphenol, wherein the 2,6-di-tert-butylmethylphenol is 2,6-di-tert-butyl-p-methylphenol and / or 2,6-di-tert-butyl-m-methylphenol. The preparation method comprises the following steps: separately passing methylphenol and isobutylene into a preheating section of a fixed-bed reactor for preheating; the methylphenol is p-methylphenol and / or m-methylphenol; mixing the preheated methylphenol and isobutylene and passing the mixture into a reaction section of the fixed-bed reactor to carry out a second reaction, thereby obtaining a second reaction solution; wherein the reaction section of the fixed-bed reactor is equipped with the above-mentioned solid acid catalyst; and separating the second reaction solution to obtain 2,6-di-tert-butylmethylphenol, wherein the 2,6-di-tert-butylmethylphenol is 2,6-di-tert-butyl-p-methylphenol and / or 2,6-di-tert-butyl-m-methylphenol. In the above preparation method, 2,6-di-tert-butylmethylphenol is prepared using methylphenol and isobutylene as raw materials and the solid acid catalyst obtained in the above preparation as a reaction catalyst in a fixed-bed reactor. This method improves production efficiency. Furthermore, the mild reaction conditions facilitate the efficient synthesis of high-purity products, reduce energy consumption, lower production costs, and improve catalyst utilization. Furthermore, the long service life of the solid acid catalyst further reduces the production cost of the above product.

[0036] In a preferred embodiment, the molar ratio of methylphenol to isobutylene is 1:(2.5-3). Controlling the molar ratio of methylphenol to isobutylene in the reaction feedstock within the above range can ensure a more complete reaction, further reduce the amount of byproducts generated, improve production efficiency, and extend the service life of the catalyst. Preferably, the molar ratio of methylphenol to isobutylene is 1:(2.5-2.8); this ratio achieves even better results. Preferably, the temperature of the preheating section is 240-260°C; preferably, the pressure of the reaction section is 0.1-0.11 MPa; preferably, the reaction section comprises a first and second reaction section connected in series, with the temperature of the first reaction section lower than that of the second reaction section; preferably, when the inner diameters of the reaction sections of the fixed-bed reactor are the same, the length ratio of the first and second reaction sections is (0.5-1):1. Passing the reaction feedstock through the first and second reaction sections connected in series, controlling the temperature of the first reaction section lower than that of the second reaction section, and maintaining the length ratio of the first and second reaction sections within the above range can further improve product yield. First, carrying out the reaction in the above two reaction stages can make the reaction more complete and further improve the conversion rate of the reaction; secondly, it can also make the reaction system safer. Preferably, the temperature of the first reaction stage is 240-260°C, and the temperature of the second reaction stage is 260-280°C; more preferably, the temperature of the first reaction stage is 250-260°C, and the temperature of the second reaction stage is 270-280°C; preferably, the mass space velocity of the reaction stage of the methylphenol and isobutylene mixed and introduced into the fixed bed reactor is 0.9-1.5h -1 Controlling the temperature of the preheating section, the temperature and pressure of the reaction section, and the mass space velocity of the mixed reaction raw materials entering the reaction section within the above ranges can make the reaction proceed better and help further improve the product yield.

[0037] In a preferred embodiment, the process of separating the second reaction solution includes: first subjecting the second reaction liquid to a first separation to obtain a crude 2,6-di-tert-butylmethylphenol product, and subjecting the crude 2,6-di-tert-butylmethylphenol product to a second separation to obtain 2,6-di-tert-butylmethylphenol; preferably, the first separation is a rectification separation and a distillation separation performed in sequence; preferably, the second separation is a crystallization separation; preferably, the crystallization separation includes: melting the crude 2,6-di-tert-butylmethylphenol product and then subjecting it to a cooling step to obtain 2,6-di-tert-butylmethylphenol. Using a two-separation method to separate the 2,6-di-tert-butylmethylphenol reaction solution prepared above can make the purity of the separated 2,6-di-tert-butylmethylphenol product higher, and can also reduce the loss during the separation process, further improving the yield. Preferably, the melting temperature is 70-71°C. Preferably, the cooling process includes cooling at a cooling rate of 2-5°C / h for 2-5 hours. More preferably, the cooling process includes cooling at a cooling rate of 2°C / h for 4-5 hours. Controlling the parameters of the crystallization separation process within the above ranges can further improve the separation effect. Preferably, the purity of the crude 2,6-di-tert-butylmethylphenol is ≥98%. Controlling the purity of the crude 2,6-di-tert-butylmethylphenol within the above range can further reduce the number of secondary separations and further improve separation efficiency.

[0038] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0039] Example 1

[0040] (1) Preparation of solid acid catalyst

[0041] 100g of a 30% aqueous solution of aluminum hydroxide was mixed with 150g of water, stirred and heated to 95°C to mix thoroughly. 60g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) 15g of potassium phosphate was added to the first slurry at this temperature to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0042] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0043] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0044] The obtained reaction solution is subjected to rectification and distillation separation in sequence to obtain crude 2,6-di-tert-butyl-p-methylphenol. The obtained crude 2,6-di-tert-butyl-p-methylphenol is placed in a crystallizer and melted, and then subjected to a cooling step to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature is 71°C, and the cooling program is 2°C / h for 5 hours. The purity of the obtained 2,6-di-tert-butyl-p-methylphenol is 99.99%. Figure 1 The 2,6-di-tert-butyl-p-methylphenol prepared 13 C NMR spectrum.

[0045] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0046] Example 2

[0047] (1) Preparation of solid acid catalyst

[0048] 100 g of a 30% aqueous solution of aluminum hydroxide was mixed with 150 g of water, stirred and heated to 95° C. to mix thoroughly. 20 g of a 30% silica sol and 0.6 g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1 hour, and mixed thoroughly to obtain a mixed slurry. 150 g of an 85% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at approximately 95° C.) 5 g of potassium hydrogen phosphate was added to the first slurry at this temperature to modify the solid components in the first slurry. After stirring for 8 hours, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90° C. with forced air for 5 hours to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0049] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0050] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0051] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0052] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0053] Example 3

[0054] (1) Preparation of solid acid catalyst

[0055] 100 g of a 30% aqueous solution of aluminum hydroxide was mixed with 200 g of water, stirred and heated to 95°C to mix thoroughly. 100 g of a 30% silica sol and 0.8 g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1 hour, and mixed thoroughly to obtain a mixed slurry. 210 g of an 85% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) 15 g of potassium dihydrogen phosphate was added to the first slurry at this temperature to modify the solid components in the first slurry. After stirring for 8 hours, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5 hours to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0056] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0057] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.8 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0058] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0059] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0060] Example 4

[0061] (1) Preparation of solid acid catalyst

[0062] 100g of a 30% aqueous solution of aluminum hydroxide was mixed with 150g of water, stirred and heated to 95°C to mix thoroughly. 60g of a 30% silica sol and 0.4g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) At this temperature, 10g of potassium phosphate was added to the first slurry to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0063] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0064] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0065] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0066] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0067] Example 5

[0068] (1) Preparation of solid acid catalyst

[0069] After mixing 100g of a 30% aqueous solution of aluminum hydroxide with 150g of water, the mixture was stirred and heated to 95°C to mix thoroughly. 40g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 185g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) At this temperature, 15g of potassium phosphate was added to the first slurry to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the solid matter obtained was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0070] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0071] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0072] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0073] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0074] Example 6

[0075] (1) Preparation of solid acid catalyst

[0076] 100g of 30% aluminum hydroxide aqueous solution was mixed with 100g of water, stirred and heated to 95°C to mix thoroughly. 40g of 30% silica sol and 0.6g of cetyltrimethylammonium bromide were added in sequence, stirred for 1h and mixed thoroughly to obtain a mixed slurry. 160g of 85wt% phosphoric acid aqueous solution was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) At this temperature, 15g of potassium phosphate was added to the first slurry to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the solid matter obtained was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0077] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0078] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0079] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0080] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0081] Example 7

[0082] (1) Preparation of solid acid catalyst

[0083] After mixing 100g of a 30% aqueous solution of aluminum hydroxide with 150g of water, the mixture was stirred and heated to 95°C to mix thoroughly. 40g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) At this temperature, 15g of potassium phosphate was added to the first slurry to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0084] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0085] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0086] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0087] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0088] Example 8

[0089] (1) Preparation of solid acid catalyst

[0090] After mixing 100g of a 30% aqueous solution of aluminum hydroxide with 150g of water, the mixture was stirred and heated to 95°C to mix thoroughly. 60g of a 30% silica sol and 0.4g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) At this temperature, 15g of potassium phosphate was added to the first slurry to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0091] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0092] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0093] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0094] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0095] Example 9

[0096] (1) Preparation of solid acid catalyst

[0097] After mixing 100 g of a 30% aqueous solution of aluminum hydroxide with 150 g of water, the mixture was stirred and heated to 95°C to mix thoroughly. 60 g of a 30% silica sol and 0.6 g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1 hour, and mixed thoroughly to obtain a mixed slurry. 150 g of an 85% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) At this temperature, 15 g of potassium phosphate was added to the first slurry to modify the solid components in the first slurry. After stirring for 8 hours, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5 hours to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0098] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0099] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0100] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0101] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0102] Example 10

[0103] (1) Preparation of solid acid catalyst

[0104] 100g of a 30% aqueous solution of aluminum hydroxide was mixed with 150g of water, stirred and heated to 95°C to mix thoroughly. 60g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) At this temperature, 10g of potassium phosphate was added to the first slurry to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0105] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0106] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0107] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0108] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0109] Example 11

[0110] (1) Preparation of solid acid catalyst

[0111] 100g of a 30% aqueous solution of aluminum hydroxide was mixed with 150g of water, stirred and heated to 95°C to mix thoroughly. 60g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) 15g of potassium phosphate was added to the first slurry at this temperature to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0112] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0113] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:3 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0114] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0115] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0116] Example 12

[0117] (1) Preparation of solid acid catalyst

[0118] 100g of a 30% aqueous solution of aluminum hydroxide was mixed with 150g of water, stirred and heated to 95°C to mix thoroughly. 60g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) 15g of potassium phosphate was added to the first slurry at this temperature to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0119] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0120] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 250°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0121] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0122] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0123] Example 13

[0124] (1) Preparation of solid acid catalyst

[0125] 100g of a 30% aqueous solution of aluminum hydroxide was mixed with 150g of water, stirred and heated to 95°C to mix thoroughly. 60g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) 15g of potassium phosphate was added to the first slurry at this temperature to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0126] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0127] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 270°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0128] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0129] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0130] Example 14

[0131] (1) Preparation of solid acid catalyst

[0132] After mixing 100 g of a 30% aqueous solution of aluminum hydroxide with 150 g of water, the mixture was stirred and heated to 95°C to mix thoroughly. 60 g of a 30% silica sol and 0.6 g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1 hour, and mixed thoroughly to obtain a mixed slurry. 160 g of an 85% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) At this temperature, 15 g of potassium phosphate was added to the first slurry to modify the solid components in the first slurry. After stirring for 8 hours, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 4 hours to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 5 hours to obtain a solid acid catalyst.

[0133] (2) Preparation of 2,6-di-tert-butyl-p-methylphenol

[0134] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:2.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0135] The resulting reaction solution is sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol is melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature is 71°C, and the cooling schedule is 5°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol has a purity of 99.99%.

[0136] The 2,6-di-tert-butyl-p-methylphenol reaction solution was detected by gas chromatography to obtain the p-methylphenol conversion rate and 2,6-di-tert-butyl-p-methylphenol selectivity data. The results are shown in Table 1.

[0137] Example 15

[0138] The difference between Example 15 and Example 1 is that the solid acid catalysts prepared are different. Specifically:

[0139] 100g of a 30% aqueous solution of aluminum hydroxide was mixed with 150g of water, stirred and heated to 95°C to mix thoroughly. 10g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction, thereby obtaining a first slurry. (During the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C.) 20g of potassium phosphate was added to the first slurry at this temperature to modify the solid components in the first slurry. After stirring for 8h, the modification was completed to obtain a second slurry. The second slurry was centrifuged, and the resulting solid matter was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450° C. for 4 hours, the calcined product was extruded into strips, and then calcined at 550° C. for 4 hours to obtain a solid acid catalyst.

[0140] Example 16

[0141] The difference between Example 16 and Example 1 is that the process for preparing 2,6-di-tert-butyl-p-methylphenol is different. Specifically:

[0142] The solid acid catalyst is placed in the reaction section of a fixed bed reactor. The reaction raw materials p-methylphenol and isobutylene are respectively introduced into the preheating section of the fixed bed reactor in a molar ratio of 1:3.5 for preheating, and then the preheated p-methylphenol and isobutylene are mixed and introduced into the first reaction section and the second reaction section connected in sequence in the fixed bed reactor (the first reaction section and the second reaction section of the fixed bed reactor have the same inner diameter) to react to obtain a reaction solution. The temperature of the preheating section of the fixed bed reactor is 260°C, the length ratio of the first reaction section and the second reaction section is 1:1; the temperature of the first reaction section is 260°C, the temperature of the second reaction section is 280°C, and the mass space velocity of the mixed material of methylphenol and isobutylene when it is introduced into the fixed bed reactor is 1.5h -1 , the absolute pressure in the reaction section is 0.11MPa.

[0143] The resulting reaction solution was sequentially subjected to rectification and distillation to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol was melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature was 71°C, and the cooling rate was 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol had a purity of 99.99%.

[0144] Comparative Example 1

[0145] The difference between Comparative Example 1 and Example 1 is that the solid acid catalyst preparation process does not include a phosphate modification step. Specifically:

[0146] After mixing 100g of a 30% aqueous solution of aluminum hydroxide with 150g of water, the mixture was stirred and heated to 95°C to mix thoroughly. 60g of a 30% silica sol and 0.6g of hexadecyltrimethylammonium bromide were added in sequence, stirred for 1h, and mixed thoroughly to obtain a mixed slurry. 160g of an 85wt% aqueous solution of phosphoric acid was added dropwise to the mixed slurry to carry out a first reaction to obtain a first slurry (during the process of adding the phosphoric acid aqueous solution to the mixed slurry, the rate of addition of the phosphoric acid aqueous solution was controlled so that the temperature of the reaction system did not change suddenly and remained at around 95°C). The first slurry obtained was centrifuged, and the solid material obtained was washed three times with water, and then dried at 90°C for 5h to obtain a solid acid catalyst precursor. The obtained solid acid catalyst precursor was transferred to a muffle furnace and calcined at 450°C for 4h. The calcined product was extruded and calcined at 550°C for 4h to obtain a solid acid catalyst.

[0147] Comparative Example 2

[0148] The difference between Comparative Example 2 and Example 1 is that the catalyst used is a sulfonic acid resin catalyst, which is purchased from Jiangyin Nanda Synthetic Chemical Co., Ltd. with the brand name Amberlyst 45.

[0149] Comparative Example 3

[0150] 108g of 99% pure p-methylphenol and 6g of sulfuric acid were mixed to obtain a reaction solution, which was then added to a stainless steel autoclave equipped with a thermometer, pressure gauge, and stirring mechanism. The reaction solution was heated to 40°C, and 0.15MPa of gaseous isobutylene was introduced to synthesize 2,6-di-tert-butyl-p-methylphenol, yielding a 2,6-di-tert-butyl-p-methylphenol reaction mixture. The reaction pressure was 0.1-0.15MPa, and the temperature was 70-80°C.

[0151] After the reaction is complete, the reaction mixture is cooled to 50°C, washed twice with water, and the lower aqueous phase is removed using a separatory funnel. The organic phase is dried over anhydrous sodium sulfate to obtain crude 2,6-di-tert-butyl-p-methylphenol. The resulting crude 2,6-di-tert-butyl-p-methylphenol is melted in a crystallizer and then cooled to obtain the 2,6-di-tert-butyl-p-methylphenol. The melting temperature is 71°C, and the cooling schedule is 2°C / h for 5 hours. The resulting 2,6-di-tert-butyl-p-methylphenol has a purity of 99.99%.

[0152] The reaction mixture of 2,6-di-tert-butyl-p-methylphenol was detected by gas chromatography to obtain the conversion rate of p-methylphenol and the selectivity data of 2,6-di-tert-butyl-p-methylphenol. The results are shown in Table 1.

[0153] The service life of the solid acid catalysts in Examples 1 to 16 and Comparative Examples 1 and 2 was calculated, and the p-methylphenol conversion, selectivity for 2,6-di-tert-butyl-p-methylphenol, and yield of 2,6-di-tert-butyl-p-methylphenol in these Examples and Comparative Examples were calculated. The results are shown in Table 1. It should be further clarified that the service life of a solid acid catalyst refers to the period of time the solid acid catalyst is used when its catalytic efficiency is less than 95% of its initial catalytic efficiency.

[0154] Table 1

[0155]

[0156]

[0157] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0158] In Example 1 to Example 16, the catalyst used in the preparation of 2,6-di-tert-butyl-p-methylphenol is a solid acid catalyst prepared by the preparation method provided in the present application. According to the data in Table 1, the solid acid catalyst in Example 1 to Example 16 can not only make the selectivity of 2,6-di-tert-butyl-p-methylphenol at a better level, the corresponding solid acid catalyst in the above embodiment also has a better service life, and the final yield of 2,6-di-tert-butyl-p-methylphenol is also more than 80%. In particular, in Example 1 to Example 14, the parameters in the preparation process of controlling the preparation of the solid acid catalyst and the synthesis of 2,6-di-tert-butyl-p-methylphenol are within the preferred range, the service life of the solid acid catalyst, the selectivity of 2,6-di-tert-butyl-p-methylphenol and the yield of 2,6-di-tert-butyl-p-methylphenol are also better, and the yield of 2,6-di-tert-butyl-p-methylphenol can even reach 89%.

[0159] In Comparative Example 1, phosphate was not used to modify the solid acid catalyst during its preparation, and a purchased catalyst was used in Comparative Example 2. In the above comparative examples, the service life of the catalyst, the selectivity of 2,6-di-tert-butyl-p-methylphenol, and the yield of 2,6-di-tert-butyl-p-methylphenol were significantly different from those in the examples of the present application. In Comparative Example 3, sulfuric acid was used as a catalyst and the reaction was carried out in an autoclave. Not only was it difficult to recycle the catalyst, but the selectivity of 2,6-di-tert-butyl-p-methylphenol and the yield of 2,6-di-tert-butyl-p-methylphenol were also significantly different from those in the examples of the present application.

[0160] In summary, the solid acid catalyst prepared using the method described in this application not only has good catalytic selectivity for the product, but also has a long cycle life. Its use in the preparation of 2,6-di-tert-butyl-p-methylphenol from p-methylphenol and isobutylene can further improve product yield and product selectivity.

[0161] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a solid acid catalyst, characterized in that: The preparation method comprises the following steps: Reaction steps: mixing aluminum hydroxide, silica sol and a template with water to obtain a mixed slurry; adding a phosphoric acid solution to the mixed slurry to carry out a first reaction to obtain a first slurry; Modification step: adding phosphate to the first slurry for modification to obtain a second slurry; separating the second slurry, washing and drying the obtained solid matter to obtain a solid acid catalyst precursor; Sintering step: The solid acid catalyst precursor is calcined to obtain the solid acid catalyst.

2. The method for preparing a solid acid catalyst according to claim 1, wherein The weight ratio of the aluminum hydroxide, the silica sol and the template is 1:(0.2-1):(0.013-0.027); Preferably, the weight ratio of the aluminum hydroxide, the silica sol and the template is 1:(0.4-0.6): (0.013～0.027)。 3. The method for preparing a solid acid catalyst according to claim 1, wherein The mass concentration of the phosphoric acid solution is 50-85%; preferably, the mass concentration of the phosphoric acid solution is 75-85%; Preferably, the amount of the phosphoric acid solution added is 5 to 7 times the weight of the aluminum hydroxide; more preferably, the amount of the phosphoric acid solution added is 5 to 6.2 times the weight of the aluminum hydroxide; Preferably, the amount of the phosphate added is 16.5-50% of the weight of the aluminum hydroxide; more preferably, the amount of the phosphate added is 33.3-50% of the weight of the aluminum hydroxide; Preferably, the aluminum hydroxide is added in the form of an aqueous solution, and the mass concentration of the aluminum hydroxide aqueous solution is 20-40%; Preferably, the mass concentration of the silica sol is 25-30%.

4. The method for preparing a solid acid catalyst according to any one of claims 1 to 3, characterized in that: The phosphate is an alkali metal phosphate and / or an ammonium phosphate; preferably, the phosphate is an alkali metal phosphate; Preferably, the alkali metal phosphate is one or more of potassium phosphate, sodium phosphate, potassium hydrogen phosphate and potassium dihydrogen phosphate; and / or, the ammonium phosphate is one or more of ammonium phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate; Preferably, the alkali metal phosphate is potassium phosphate; Preferably, the template agent is one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium bicarbonate and cetyltrimethylammonium bromide; preferably, the template agent is cetyltrimethylammonium bromide; Preferably, in the reaction step, the weight ratio of the water to the aluminum hydroxide is (3.3-6.6):1; preferably, in the reaction step, the weight ratio of the water to the aluminum hydroxide is (3.3-5):

1.

5. The method for preparing a solid acid catalyst according to any one of claims 1 to 4, characterized in that: The calcination comprises: performing a first calcination on the solid acid catalyst precursor to obtain a first calcined product; shaping the first calcined product, and then performing a second calcination to obtain the solid acid catalyst; Preferably, the shaping operation is performed on the first calcined product using an extruder; Preferably, the diameter of the first calcined product after molding is 3 to 6 mm; Preferably, the first calcination temperature is 400-500°C and the time is 2-6 hours; Preferably, the second calcination temperature is 500-600°C and the time is 2-6 hours; Preferably, the drying temperature is 70-120°C and the drying time is 3-6 hours; Preferably, the process of mixing the aluminum hydroxide, the silica sol and the template with the water comprises: mixing the aluminum hydroxide and the water at a first temperature, and then sequentially adding the silica sol and the template thereto to obtain the mixed slurry; Preferably, the first temperature is 80-100°C; Preferably, after adding the phosphate to the first slurry, the mixed slurry is subjected to a first mixing process to perform the modification; preferably, the first mixing time is 6 to 10 hours.

6. A solid acid catalyst, characterized in that The solid acid catalyst is prepared by the preparation method of the solid acid catalyst according to any one of claims 1 to 5.

7. Use of the solid acid catalyst according to claim 6, characterized in that: The solid acid catalyst is used to catalyze the reaction of methylphenol and isobutylene to prepare 2,6-di-tert-butylmethylphenol; wherein the methylphenol is p-methylphenol and / or m-methylphenol, and the 2,6-di-tert-butylmethylphenol is 2,6-di-tert-butyl-p-methylphenol and / or 2,6-di-tert-butyl-m-methylphenol.

8. A method for preparing 2,6-di-tert-butylmethylphenol, wherein the 2,6-di-tert-butylmethylphenol is 2,6-di-tert-butyl-p-methylphenol and / or 2,6-di-tert-butyl-m-methylphenol, characterized in that: The preparation method comprises the following steps: respectively introducing methylphenol and isobutylene into the preheating section of a fixed bed reactor for preheating; the methylphenol is p-methylphenol and / or m-methylphenol; The preheated methylphenol and the isobutylene are mixed and introduced into the reaction section of the fixed bed reactor to perform a second reaction to obtain a second reaction solution; wherein the reaction section is filled with the solid acid catalyst according to claim 6; The second reaction solution is separated to obtain the 2,6-di-tert-butylmethylphenol; the 2,6-di-tert-butylmethylphenol is the 2,6-di-tert-butyl-p-methylphenol and / or the 2,6-di-tert-butyl-m-methylphenol.

9. The method for preparing 2,6-di-tert-butylmethylphenol according to claim 8, wherein The molar ratio of the methylphenol to the isobutylene is 1:(2.5-3); preferably, the molar ratio of the methylphenol to the isobutylene is 1: (2.5～2.8)； Preferably, the temperature of the preheating section is 240-260°C; Preferably, the pressure of the reaction section is 0.1 to 0.11 MPa; Preferably, the reaction section comprises a first reaction section and a second reaction section connected in sequence, and the temperature of the first reaction section is lower than the temperature of the second reaction section; Preferably, when the inner diameters of the reaction sections of the fixed bed reactor are the same, the length ratio of the first reaction section to the second reaction section is (0.5-1):1; Preferably, the temperature of the first reaction section is 240-260°C, and the temperature of the second reaction section is 260-280°C; More preferably, the temperature of the first reaction section is 250-260°C, and the temperature of the second reaction section is 270-280°C; Preferably, the mass space velocity of the reaction section of the fixed bed reactor after the methylphenol and the isobutylene are mixed is 0.9 to 1.5 h -1 .

10. The method for preparing 2,6-di-tert-butylmethylphenol according to claim 8 or 9, characterized in that: The process of separating the second reaction solution includes: first subjecting the second reaction liquid to a first separation to obtain a crude 2,6-di-tert-butylmethylphenol product, and subjecting the crude 2,6-di-tert-butylmethylphenol to a second separation to obtain the 2,6-di-tert-butylmethylphenol product; Preferably, the first separation comprises rectification separation and distillation separation performed sequentially; Preferably, the second separation is crystallization separation; Preferably, the crystallization separation comprises: melting the crude 2,6-di-tert-butylmethylphenol and then cooling it to obtain the 2,6-di-tert-butylmethylphenol; Preferably, the melting temperature is 70-71°C; Preferably, the cooling procedure includes: cooling at a cooling rate of 2 to 5°C / h for 2 to 5 hours; More preferably, the cooling program includes: cooling at a cooling rate of 2°C / h for 4 to 5 hours.

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