Preparation method and application of p-tert-butyltoluene

Abstract

The invention provides a preparation method and application of p-tert-butyltoluene. By adopting the hierarchical porous SAPO-5 molecular sieve catalyst with the microporous-mesoporous composite structure, a meta-position product can be promoted to be converted into a para-position product, the isomerization reaction performance is effectively improved, the side chain cracking reaction is reduced, and the yield of para-tert-butyltoluene is further improved, so that the economical efficiency of the reaction is remarkably improved, and the method has relatively great industrial application potential.

Description

Technical Field

[0001] The invention belongs to the field of tert-butyltoluene preparation, and specifically relates to a preparation method and application of p-tert-butyltoluene. Background Art

[0002] p-tert-Butyltoluene (P-TBTO) is a derivative of toluene. It is a colorless and transparent liquid and an organic intermediate with important value. It can be used to prepare p-tert-butylbenzoic acid, p-tert-butylbenzyl chloride, p-tert-butylbenzaldehyde, methyl p-tert-butylbenzoate, p-tert-butylbenzonitrile, etc. Among them, p-tert-butylbenzoic acid is mainly used in the synthesis of polymer materials such as alkyd resins, or as a metalworking fluid and lubricant additive. p-tert-Butylbenzyl chloride is widely used in the production of medicines and pesticides, and can be used as an intermediate to synthesize the new insecticide cypermethrin. p-tert-Butylbenzaldehyde is an important raw material in fine chemical products such as medicines, dyes, flavors and fragrances, and electronic chemicals. It is an intermediate in the production of anti-allergic drugs anqimin and chlorpheniramine hydrochloride. In addition, p-tert-Butylbenzaldehyde is in great demand in the synthesis of flavors and fragrances such as lily of the valley aldehyde.

[0003] The preparation of tert-butyltoluene is a typical alkylation reaction based on the Friedel-Crafts reaction mechanism, which can be synthesized through three pathways: reaction of isobutylene with toluene, reaction of tert-butyl chloride with toluene, and reaction of tert-butyl alcohol with toluene. Traditional alkylation reactions often use liquid acids such as sulfuric acid, anhydrous AlCl3, BF3, etc. as catalysts for the reaction. These liquid acid catalysts have the disadvantages of short service life, difficulty in post-treatment, serious environmental pollution, and high requirements for equipment corrosion resistance. In order to overcome these problems, environmentally friendly catalysts such as solid superacid catalysts, molecular sieve catalysts, and heteropolyacid catalysts have appeared in recent years. Solid acid catalysts have significant advantages, including high yield of target products, easy separation of catalysts, low environmental pollution, and long service life of catalysts. Therefore, solid acid heterogeneous catalysts gradually began to replace liquid acid catalysts, but the reaction process still has problems. For example, in the reaction process of patent CN102557858A and literature report (Research on the synthesis of p-tert-butyltoluene catalyzed by HM-supported phosphotungstic acid, Modern Chemical Industry 2013, Vol. 6, No. 33), the para-product yield of the solid acid catalyst is still insufficient, which can ensure that about 80% of the alkylation products are p-tert-butyltoluene, but inevitably about 20% of the products are m-tert-butyltoluene, causing two problems: first, p-tert-butyltoluene is of high value, and the presence of a part of m-tert-butyltoluene reduces the economy of the entire process; second, the separation cost is increased, m-tert-butyltoluene and p-tert-butyltoluene have close boiling points, and additional distillation is required to separate the above two, resulting in additional energy consumption, so it is necessary to convert this part of the m-product to further improve its economic value. Summary of the invention

[0004] In order to solve the above technical problems, the present invention develops a fixed bed isomerization reaction process with simple reaction process and high yield, which is used for isomerization of m-tert-butyltoluene to prepare p-tert-butyltoluene. Moreover, the method adopts SAPO-5 molecular sieve with microporous-mesoporous composite structure, which has a high yield of p-tert-butyltoluene.

[0005] One of the purposes of the present invention is to provide a method for preparing p-tert-butyltoluene, comprising the step of contacting a raw material with a catalyst containing a SAPO-5 molecular sieve to react and prepare p-tert-butyltoluene, wherein the SAPO-5 molecular sieve has a microporous-mesoporous composite structure.

[0006] According to the present invention, the SAPO-5 molecular sieve used in the reaction is:

[0007] The specific surface area of ​​the SAPO-5 molecular sieve is 250 to 350 m 2 ·g -1 The specific surface area of ​​the mesopores is 20 to 80 m 2 ·g -1 Specifically, the specific surface area of ​​the SAPO-5 molecular sieve can be 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350 m 2 ·g -1 Any value or range between any two values, wherein the specific surface area of ​​the mesopores can be 20, 30, 40, 50, 60, 70, 80 m 2 ·g -1 Any value or range between any two values; preferably, the specific surface area of ​​the SAPO-5 molecular sieve is 280 to 330 m 2 ·g -1 The specific surface area of ​​the mesopores is 30 to 60 m 2 ·g -1 ;

[0008] The silicon-to-aluminum ratio on the surface of the SAPO-5 molecular sieve is 0.05-0.3. For example, the silicon-to-aluminum ratio on the surface of the SAPO-5 molecular sieve can be any value among 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, and 0.3, or the range between any two values. Preferably, the silicon-to-aluminum ratio on the surface of the SAPO-5 molecular sieve is 0.1-0.2, wherein the silicon-to-aluminum ratio is the molar ratio of the respective oxides of silicon and aluminum.

[0009] According to the present invention, in the method for preparing p-tert-butyltoluene:

[0010] The raw material contains m-tert-butyltoluene, which can be any raw material containing m-tert-butyltoluene in the art. The content of tert-butyltoluene in the raw material is not particularly limited. Preferably, the content of m-tert-butyltoluene in the raw material is 15-35wt%;

[0011] The reaction can adopt the reaction conditions commonly used in the preparation of intermediate tert-butyltoluene in the prior art, for example, the reaction conditions are: reaction temperature of 200-350° C., reaction liquid hourly space velocity of 0.5-2 h -1 , the reaction pressure is 0.1~2MPa.

[0012] According to the present invention, the SAPO-5 molecular sieve having a microporous-mesoporous composite structure is obtained by stirring and reacting an aluminum source, a phosphorus source, a silicon source, a template agent R1 and a template agent R2, and then aging, crystallizing, drying and calcining. The template agent R1 is an organic amine compound, and the template agent R2 is an alkyl phosphate compound. An appropriate amount of the alkyl phosphate compound can promote the formation of an additional mesoporous structure in the molecular sieve, increase the proportion of the mesoporous structure in the molecular sieve, and adjust the pore size of the molecular sieve. Excessive alkyl phosphate compounds will affect crystallization, resulting in a lower specific surface area, and affect the catalytic performance of the molecular sieve.

[0013] According to the present invention, the method for preparing the SAPO-5 molecular sieve having a microporous-mesoporous composite structure comprises:

[0014] 1) dispersing an aluminum source in water to form a slurry I;

[0015] 2) adding a phosphorus source to the slurry I to form a sol II, and stirring the sol II;

[0016] 3) adding a silicon source dropwise to the stirred sol II to form sol III;

[0017] 4) adding template R1 to sol III, and then continuing to add template R2, and performing aging treatment after the addition is completed to obtain a gel precursor;

[0018] 5) The gel precursor after aging treatment is transferred into a crystallization kettle and crystallized under stirring conditions;

[0019] 6) After the crystallization is completed, the SAPO-5 molecular sieve is obtained by centrifugation, washing, drying and calcination.

[0020] According to the present invention, in the method for preparing the SAPO-5 molecular sieve having a microporous-mesoporous composite structure:

[0021] The aluminum source can be an aluminum-containing compound commonly used in the art for preparing molecular sieves, for example, the aluminum source is selected from at least one of pseudo-boehmite, aluminum hydroxide, sodium metaaluminate, and aluminum isopropoxide;

[0022] The phosphorus source may be a phosphorus source compound commonly used in the art for preparing molecular sieves, for example, the phosphorus source is selected from phosphoric acid;

[0023] The silicon source may be a silicon-containing compound commonly used in the art for preparing molecular sieves, for example, the silicon source is selected from at least one of ethyl orthosilicate, white carbon black, and silica sol;

[0024] The template agent R1 is selected from at least one of organic amine compounds, preferably at least one of tetraethylammonium hydroxide, triethylamine, tripropylamine, and tetrapropylammonium hydroxide;

[0025] The template R2 is selected from at least one of alkyl phosphoric acid, preferably at least one of dodecyl phosphoric acid, tetradecyl phosphoric acid and hexadecyl phosphoric acid.

[0026] According to the present invention, in the preparation method of the SAPO-5 molecular sieve with a microporous-mesoporous composite structure, the mass ratio of the aluminum source, phosphorus source, silicon source, template R1, template R2, and water is 1: (1-1.3): (0.1-0.4): (1.1-2.0): (0.025-0.3): (25-100), wherein the aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, and the silicon source is calculated as SiO2; preferably, the mass ratio of the aluminum source, silicon source, template R1, template R2, and water is 1: (1-1.1): (0.25-0.35): (1.3-1.7): (0.05-0.25): (30-60), wherein the aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, and the silicon source is calculated as SiO2.

[0027] According to the present invention, the preparation method of the SAPO-5 molecular sieve having a microporous-mesoporous composite structure is as follows:

[0028] The stirring conditions in step 2) are not particularly limited, and conventional stirring conditions can be used. For example, the stirring conditions are: temperature of 20 to 60° C., and time of 1 to 6 hours;

[0029] The aging conditions in step 4) are not particularly limited, and the aging conditions commonly used in the art can be adopted. For example, the aging conditions are: temperature of 20 to 80° C., and time of 1 to 12 h;

[0030] The crystallization conditions in step 5) are not particularly limited, and the crystallization conditions commonly used in the art can be adopted. For example, the crystallization conditions are: temperature of 160-190° C., and time of 16-36 h;

[0031] The drying conditions in step 6) are not particularly limited, and conventional drying conditions may be used, for example, the drying conditions are: a temperature of 100 to 125° C. and a time of 4 to 16 hours;

[0032] The calcination conditions in step 6) are not particularly limited, and the calcination conditions commonly used in the art can be adopted. For example, the calcination conditions are: temperature of 500-700° C. and time of 2-6 hours.

[0033] The second object of the present invention is to provide a method for preparing the above-mentioned p-tert-butyltoluene, and its application in preparing p-tert-butyltoluene by isomerization reaction using components containing m-tert-butyltoluene as raw materials.

[0034] According to the present invention, the isomerization reaction is carried out in a fixed bed reactor; the conditions of the isomerization reaction are: the reaction temperature is 200-350°C, the reaction liquid hourly space velocity is 0.5-2h -1 , the reaction pressure is 0.1~2MPa.

[0035] Solid acid catalysts, especially molecular sieve catalysts, can also be used as isomerization catalysts to promote the conversion of meta products into para products, and the key to the reaction lies in the selection of molecular sieve pore structure and the matching of acidity. Therefore, taking appropriate means to adjust the molecular sieve pore size and modifying the acidity at the same time can effectively improve the isomerization reaction performance. The SAPO-5 molecular sieve with a microporous-mesoporous composite structure used in the present invention has a more suitable straight-through pore, and the acidity distribution is more reasonable, which can effectively improve the isomerization selectivity while reducing the cracking reaction of the side chain. At the same time, after introducing multi-level pores, it is more conducive to the diffusion of reactants and product molecules, which has a promoting effect on promoting the conversion of meta isomers, thereby significantly improving the economy of the reaction.

[0036] Compared with a kettle reactor, the preparation method of the SAPO-5 molecular sieve with a microporous-mesoporous composite structure adopted in the present invention is simple and has a low reaction cost. The special microporous-mesoporous composite structure in the SAPO-5 molecular sieve has a strong production capacity of p-tert-butyltoluene and also shows a high yield of the target product, which can effectively improve the economic value of the toluene tert-butylation reaction and make full use of the reaction product. In addition, the preparation method of p-tert-butyltoluene provided by the present invention has the characteristics of simple reaction process, high reaction efficiency, continuous production, etc., and has great industrial application potential. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0038] The test instruments and test conditions used in the embodiments of the present invention are as follows:

[0039] Molecular sieve specific surface area: The specific surface area of ​​the catalyst was determined using a Micrometritics ASAP 2020M analyzer. The adsorbate was N2, which was adsorbed at liquid nitrogen temperature. The specific surface area of ​​the catalyst was calculated using the BET equation.

[0040] Molecular sieve surface silicon-aluminum ratio: The catalyst surface silicon-aluminum ratio was analyzed using a Perkin Elmer phi 5000c X-ray photoelectron spectrometer (XPS) with a Mg Kα X-ray source, an operating voltage of 15 kV, and a current of 20 mA. All spectra were calibrated with C1s of 284.8 eV as the standard.

[0041] Contents of tert-butyltoluene and p-tert-butyltoluene in the materials: The reaction products were analyzed by normalization method using an Agilent 7890A gas chromatograph equipped with a hydrogen flame detector (FID).

[0042] In the embodiment of the present invention, the conversion rate of m-tert-butyltoluene and the yield of p-tert-butyltoluene are defined as follows:

[0043]

[0044]

[0045] The catalyst embodiments of the present invention are evaluated using The reaction is carried out in a fixed bed reactor with a length of 800 mm, a catalyst loading amount of 1 g, and a reaction system pressure of 0.1 to 1 MPa.

[0046] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0047] [Example 1]

[0048] Preparation of SAPO-5 molecular sieve:

[0049] The molecular sieve synthesis gel ratio is Al2O3:P2O5:SiO2:R1:R2:H2O=1:1.05:0.25:1.5:0.08:50, the aluminum source is pseudo-boehmite, the phosphorus source is phosphoric acid, the stirring treatment time is 2h, the temperature is 30°C, the silicon source is silica sol, the template R1 is triethylamine, the template R2 is tetradecyl phosphoric acid, the gel precursor aging time is 4h, the aging temperature is 50°C, the crystallization temperature is 180°C, and the crystallization time is 20h. The specific preparation process is as follows:

[0050] 1) dispersing an aluminum source in a required amount of water to form a slurry I;

[0051] 2) Slowly add the required amount of phosphorus source to the slurry I to form sol II, and stir at 30°C for 2h;

[0052] 3) adding a silicon source dropwise to the stirred sol II to form sol III;

[0053] 4) slowly adding the required amount of template R1 to sol III, and then slowly adding template R2, and aging at 50° C. for 4 h to obtain a gel precursor;

[0054] 5) The gel precursor after aging treatment is transferred into a crystallization reactor with stirring and crystallized at 180° C. for 20 h under stirring;

[0055] 6) After crystallization, the molecular sieve was centrifuged, washed, dried at 100°C for 4 h, and then calcined at 550°C for 4 h.

[0056] The specific surface area of ​​the synthesized SAPO-5 molecular sieve was 285.6 m 2 ·g -1 , of which the mesopore specific surface area is 37.0m 2 ·g -1 , surface Si:P=0.18.

[0057] Preparation of tert-butyltoluene:

[0058] The SAPO-5 molecular sieve obtained after calcination is sieved after tabletting, and particles of 40 to 60 meshes are selected for reaction.

[0059] The content of m-tert-butyltoluene in the reaction raw materials was 26.5 wt %. The reaction temperature was 260° C. and the reaction liquid hourly space velocity was 1.0 h -1 , the reaction pressure was 1.5 MPa, the conversion rate of m-tert-butyltoluene was 75.2%, and the yield of p-tert-butyltoluene was 65.4%.

[0060] [Example 2]

[0061] Preparation of SAPO-5 molecular sieve:

[0062] The preparation process of SAPO-5 molecular sieve is the same as that of Example 1, except that:

[0063] The molecular sieve synthesis gel ratio is Al2O3:P2O5:SiO2:R1:R2:H2O=1:1.05:0.35:1.7:0.14:55, the aluminum source is aluminum isopropoxide, the phosphorus source is phosphoric acid, the stirring treatment time is 1h, the temperature is 30°C, the silicon source is tetraethyl orthosilicate, the template R1 is tetraethylammonium hydroxide, the template R2 is hexadecyl phosphoric acid, the gel precursor aging time is 6h, the aging temperature is 60°C, the crystallization temperature is 190°C, and the crystallization time is 24h.

[0064] The specific surface area of ​​the synthesized SAPO-5 molecular sieve is 303.8 m 2 ·g -1 , of which the mesopore specific surface area is 43.1m 2 ·g -1 , surface Si:P=0.15.

[0065] Preparation of tert-butyltoluene:

[0066] The content of m-tert-butyltoluene in the reaction raw materials was 20.4 wt %. The reaction temperature was 270° C. and the reaction liquid hourly space velocity was 1.0 h -1 , the reaction pressure was 1.5 MPa, the conversion rate of m-tert-butyltoluene was 73.0%, and the yield of p-tert-butyltoluene was 62.8%.

[0067] [Example 3]

[0068] Preparation of SAPO-5 molecular sieve:

[0069] The preparation process of SAPO-5 molecular sieve is the same as that of Example 1, except that:

[0070] The molecular sieve synthesis gel ratio is Al2O3:P2O5:SiO2:R1:R2:H2O=1:1.13:0.3:1.65:0.18:60, the aluminum source is aluminum isopropoxide, the phosphorus source is phosphoric acid, the stirring treatment time is 1h, the temperature is 30°C, the silicon source is tetraethyl orthosilicate, the template R1 is tetraethylammonium hydroxide, the template R2 is hexadecyl phosphoric acid, the gel precursor aging time is 5h, the aging temperature is 40°C, the crystallization temperature is 185°C, and the crystallization time is 24h.

[0071] The specific surface area of ​​the synthesized SAPO-5 molecular sieve was 295.3 m 2 ·g -1 , of which the mesopore specific surface area is 51.7m 2 ·g -1 , surface Si:P=0.17.

[0072] Preparation of tert-butyltoluene:

[0073] The content of m-tert-butyltoluene in the reaction raw materials was 25.2 wt %. The reaction temperature was 250° C. and the hourly space velocity of the reaction liquid was 0.8 h -1 , the reaction pressure was 2.0 MPa, the conversion rate of m-tert-butyltoluene was 74.6%, and the yield of p-tert-butyltoluene was 63.8%.

[0074] [Example 4]

[0075] Preparation of SAPO-5 molecular sieve:

[0076] The preparation process of SAPO-5 molecular sieve is the same as that of Example 1, except that:

[0077] The molecular sieve synthesis gel ratio is Al2O3:P2O5:SiO2:R1:R2:H2O=1:1.07:0.33:1.5:0.10:60, the aluminum source is aluminum isopropoxide, the phosphorus source is phosphoric acid, the stirring treatment time is 1h, the temperature is 30°C, the silicon source is white carbon black, the template R1 is tripropylamine, the template R2 is dodecyl phosphoric acid, the gel precursor aging time is 6h, the aging temperature is 40°C, the crystallization temperature is 180°C, and the crystallization time is 20h.

[0078] The specific surface area of ​​the synthesized SAPO-5 molecular sieve is 323.6 m 2 ·g -1 , of which the mesopore specific surface area is 31.1m 2 ·g -1 , surface Si:P=0.20.

[0079] Preparation of tert-butyltoluene:

[0080] The content of m-tert-butyltoluene in the reaction raw materials was 21.5 wt %. The reaction temperature was 260° C. and the reaction liquid hourly space velocity was 1.0 h -1 , the reaction pressure was 1.0 MPa, the conversion rate of m-tert-butyltoluene was 69.8%, and the yield of p-tert-butyltoluene was 60.5%.

[0081] [Example 5]

[0082] Preparation of SAPO-5 molecular sieve:

[0083] The preparation process of SAPO-5 molecular sieve is the same as that of Example 1, except that:

[0084] The molecular sieve synthesis gel ratio is Al2O3:P2O5:SiO2:R1:R2:H2O=1:1.0:0.3:1.6:0.14:50, aluminum source is aluminum hydroxide, phosphoric acid is phosphoric acid, stirring treatment time is 1h, temperature is 40°C, silicon source is silica sol, template R1 is tripropylamine, template R2 is tetradecyl phosphoric acid, gel precursor aging time is 6h, aging temperature is 60°C, crystallization temperature is 190°C, crystallization time is 16h.

[0085] The specific surface area of ​​the synthesized SAPO-5 molecular sieve is 303.8 m 2 ·g -1 The mesopore specific surface area is 44.2 m 2 ·g -1 , surface Si:P=0.18.

[0086] Preparation of tert-butyltoluene:

[0087] The content of m-tert-butyltoluene in the reaction raw materials was 22.1 wt%. The reaction temperature was 280°C and the hourly space velocity of the reaction liquid was 0.75 h -1 , the reaction pressure was 1.8 MPa, the conversion rate of m-tert-butyltoluene was 71.3%, and the yield of p-tert-butyltoluene was 64.5%.

[0088] [Example 6]

[0089] Preparation of SAPO-5 molecular sieve:

[0090] The preparation process of SAPO-5 molecular sieve is the same as that of Example 1, except that:

[0091] The molecular sieve synthesis gel ratio is Al2O3:P2O5:SiO2:R1:R2:H2O=1:1.06:0.28:1.4:0.1:45, the aluminum source is aluminum isopropoxide, the phosphorus source is phosphoric acid, the stirring treatment time is 1h, the temperature is 40°C, the silicon source is tetraethyl orthosilicate, the template R1 is triethylamine, the template R2 is tetradecyl phosphoric acid, the gel precursor aging time is 11h, the aging temperature is 50°C, the crystallization temperature is 180°C, and the crystallization time is 18h.

[0092] The specific surface area of ​​the synthesized SAPO-5 molecular sieve was 318.6 m 2 ·g -1 , of which the mesopore specific surface area is 39.0m 2 ·g -1 , surface Si:P=0.13.

[0093] Preparation of tert-butyltoluene:

[0094] The content of m-tert-butyltoluene in the reaction raw materials was 25.1 wt%. The reaction temperature was 260°C and the hourly space velocity of the reaction liquid was 1.0 h -1 , the reaction pressure was 0.2 MPa, the conversion rate of m-tert-butyltoluene was 68.9%, and the yield of p-tert-butyltoluene was 56.4%.

[0095] [Comparative Example 1]

[0096] Preparation of SAPO-5 molecular sieve:

[0097] The preparation process of SAPO-5 molecular sieve is the same as that of Example 1, except that:

[0098] The molecular sieve synthesis gel ratio is Al2O3:P2O5:SiO2:R1:H2O=1:1.05:0.25:1.5:50, the aluminum source is pseudo-boehmite, the phosphorus source is phosphoric acid, the stirring treatment time is 2h, the temperature is 30°C, the silicon source is silica sol, the template R1 is triethylamine, the gel precursor aging time is 4h, the aging temperature is 50°C, the crystallization temperature is 180°C, and the crystallization time is 20h.

[0099] The specific surface area of ​​the synthesized SAPO-5 molecular sieve was 293.7 m 2 ·g -1 , of which the mesopore specific surface area is 11.3m 2 ·g -1 , surface Si:P=0.22.

[0100] Preparation of tert-butyltoluene:

[0101] The content of m-tert-butyltoluene in the reaction raw materials was 26.5 wt %. The reaction temperature was 260° C. and the reaction liquid hourly space velocity was 1.0 h -1 , the reaction pressure was 1.5 MPa, the conversion rate of m-tert-butyltoluene was 74.8%, and the yield of p-tert-butyltoluene was 54.6%.

[0102] [Comparative Example 2]

[0103] Preparation of SAPO-5 molecular sieve:

[0104] The preparation process of SAPO-5 molecular sieve is the same as that of Example 1, except that:

[0105] The molecular sieve synthesis gel ratio is Al2O3:P2O5:SiO2:R1:R2:H2O=1:1.25:0.25:1.5:0.6:50, the aluminum source is pseudo-boehmite, the phosphorus source is phosphoric acid, the stirring treatment time is 2h, the temperature is 30°C, the silicon source is silica sol, the template R1 is triethylamine, the template R2 is tetradecyl phosphoric acid, the gel precursor aging time is 4h, the aging temperature is 50°C, the crystallization temperature is 180°C, and the crystallization time is 20h.

[0106] The specific surface area of ​​the synthesized SAPO-5 molecular sieve was 198.5 m 2 ·g -1 , of which the mesopore specific surface area is 7.5m 2 ·g -1 , surface Si:P=0.23.

[0107] Preparation of tert-butyltoluene:

[0108] The content of m-tert-butyltoluene in the reaction raw materials was 26.5 wt %. The reaction temperature was 260° C. and the reaction liquid hourly space velocity was 1.0 h -1 , the reaction pressure was 1.5 MPa, the conversion rate of m-tert-butyltoluene was 42.3%, and the yield of p-tert-butyltoluene was 13.5%.

Claims

1. A method for preparing p-tert-butyltoluene, comprising the step of contacting a raw material with a catalyst containing a SAPO-5 molecular sieve to react and prepare p-tert-butyltoluene, wherein the SAPO-5 molecular sieve has a microporous-mesoporous composite structure, and the specific surface area of ​​the SAPO-5 molecular sieve is 250 to 350 m 2 ·g -1 The specific surface area of ​​the mesopores is 20 to 80 m 2 ·g -1 .

2. The preparation method according to claim 1, characterized in that: The specific surface area of ​​the SAPO-5 molecular sieve is 280 to 330 m 2 ·g -1 The specific surface area of ​​the mesopores is 30 to 60 m 2 ·g -1 and / or, The silicon-to-aluminum ratio on the surface of the SAPO-5 molecular sieve is 0.05 to 0.3, preferably 0.1 to 0.2, wherein the silicon-to-aluminum ratio is the molar ratio of silicon and aluminum oxides.

3. The preparation method according to claim 1, characterized in that: The raw material contains m-tert-butyltoluene, preferably, the content of m-tert-butyltoluene in the raw material is 15-35wt%; and / or, The reaction conditions are: reaction temperature is 200-350°C, reaction liquid hourly space velocity is 0.5-2h -1 , the reaction pressure is 0.1~2MPa.

4. The preparation method according to claim 1, characterized in that: The SAPO-5 molecular sieve with a microporous-mesoporous composite structure is obtained by stirring and reacting an aluminum source, a phosphorus source, a silicon source, a template agent R1 and a template agent R2, and then aging, crystallizing, drying and calcining.

5. The preparation method according to claim 4, characterized in that: The preparation method of the SAPO-5 molecular sieve comprises: 1) dispersing an aluminum source in water to form a slurry I; 2) adding a phosphorus source to the slurry I to form a sol II, and stirring the sol II; 3) adding a silicon source dropwise to the stirred sol II to form sol III; 4) adding template R1 to sol III, and then continuing to add template R2, and performing aging treatment after the addition is completed to obtain a gel precursor; 5) The gel precursor after aging treatment is transferred into a crystallization kettle and crystallized under stirring conditions; 6) After the crystallization is completed, the SAPO-5 molecular sieve is obtained by centrifugation, washing, drying and calcination.

6. The preparation method according to claim 5, characterized in that: The aluminum source is selected from at least one of pseudo-boehmite, aluminum hydroxide, sodium aluminate, and aluminum isopropoxide; and / or, The phosphorus source is selected from phosphoric acid; and / or, The silicon source is selected from at least one of tetraethyl orthosilicate, white carbon black and silica sol; and / or, The template agent R1 is selected from at least one of organic amine compounds, preferably at least one of tetraethylammonium hydroxide, triethylamine, tripropylamine, and tetrapropylammonium hydroxide; and / or, The template R2 is selected from at least one of alkyl phosphoric acid compounds, preferably at least one of dodecyl phosphoric acid, tetradecyl phosphoric acid and hexadecyl phosphoric acid.

7. The preparation method according to claim 5, characterized in that: The mass ratio of the aluminum source, phosphorus source, silicon source, template R1, template R2 and water is 1: (1-1.3): (0.1-0.4): (1.1-2.0): (0.025-0.3): (25-100), wherein the aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, and the silicon source is calculated as SiO2; preferably, the mass ratio of the aluminum source, silicon source, template R1, template R2 and water is 1: (1-1.1): (0.25-0.35): (1.3-1.7): (0.05-0.25): (30-60), wherein the aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, and the silicon source is calculated as SiO2.

8. The preparation method according to claim 5, characterized in that: The stirring conditions in step 2) are: temperature of 20 to 60° C. and time of 1 to 6 hours; and / or, The aging conditions in step 4) are: temperature of 20-80° C., time of 1-12 h; and / or, The crystallization conditions in step 5) are: temperature of 160-190° C. and time of 16-36 hours; and / or, The drying conditions in step 6) are: temperature of 100-125° C. and time of 4-16 hours; and / or, The calcination conditions in step 6) are: temperature of 500-700° C. and time of 2-6 hours.

9. A method for preparing p-tert-butyltoluene according to any one of claims 1 to 8, and use thereof in preparing p-tert-butyltoluene by isomerization reaction using components containing m-tert-butyltoluene as raw materials.

10. The use according to claim 9, characterized in that: The isomerization reaction is carried out in a fixed bed reactor; and / or, The isomerization reaction conditions are: reaction temperature is 200-350°C, reaction liquid hourly space velocity is 0.5-2h -1 , the reaction pressure is 0.1~2MPa.

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