Method for synthesizing durene through alkylation of unsym-trimethylbenzene and methanol

Abstract

The invention relates to a method for synthesizing durene through alkylation of unsym-trimethylbenzene and methanol, and the method comprises the following step: under alkylation reaction conditions and in the presence of a catalyst, enabling unsym-trimethylbenzene to be in contact with methanol, the catalyst comprises an IMF structure molecular sieve, the total pore volume of the IMF structure molecular sieve is 0.2-0.4 cm < 3 >. G <-1 >, and the mesopore volume is 0.08-0.3 cm < 3 >. G <-1 >. According to the present invention, the IMF structure molecular sieve having the large pore channel structure is adopted as the catalyst, such that the unsym-trimethylbenzene conversion rate, the durene selectivity and the tetramethylbenzene selectivity can be easily improved, and the selectivity of the by-product C6-C8 aromatic hydrocarbon can be reduced;

Description

Technical Field

[0001] The present disclosure relates to the technical field of alkylation, and in particular to a method for synthesizing durene by alkylating trimethylolbenzene with methanol. Background Art

[0002] Durene is a high value-added fine chemical raw material and the main raw material for the production of pyromellitic anhydride (PMDA). PMDA and diamines such as 4,4'-diaminodiphenyl ether (ODA) are used to produce polyimide (PI). PI is an important class of polymer materials and is widely used in filter membranes, aerospace composites, electronic-grade coatings and adhesives. In recent years, the main methods for synthesizing durene are separation method and synthesis method: the separation method is to obtain polyimide from C 10 The process of purifying durene from reformed heavy aromatics or methanol synthetic oil by combining distillation and crystallization (or adsorption) is complex, with high energy consumption and low separation accuracy. The synthesis method includes chloromethylation of trimethylol, disproportionation / isomerization of trimethylol, isomerization of tetramethylol and alkylation of trimethylol. Among them, the alkylation reaction of trimethylol and methanol has attracted wide attention due to its low cost, high product yield, low energy consumption, no pollution and no corrosion.

[0003] CN112619687A discloses the preparation and use of a catalyst for synthesizing durene from the alkylation of unsymmetrical trimethylbenzene and methanol. First, a ZSM-5 molecular sieve with a silicon-aluminum ratio of 100-150 is exchanged with 0.2-2.0 mol / L dilute hydrochloric acid to form a hydrogen-type molecular sieve HZSM-5. After forming, non-framework aluminum is washed away with 1.0-3.0 mol / L dilute nitric acid, and then, it is fully washed with a potassium chloride solution for 3-8 times, and magnesium is modified by a magnesium nitrate impregnation method to obtain a modified HZSM-5 molecular sieve with potassium chloride and magnesium nitrate loadings of 8-15% and 5-10%, respectively. After the catalyst is formed, it is used for the alkylation reaction of unsymmetrical trimethylbenzene and methanol, and its durene selectivity is 8-30%.

[0004] The catalyst with modified ZSM-5 molecular sieve (MFI structure) as the catalytic active component has a conversion rate of 20-35% in the prior art. 6 -C 8 The selectivity of aromatic by-products is 15-25%. Summary of the invention

[0005] The purpose of the present invention is to provide a method for synthesizing durene by alkylation of trimethylolbenzene with methanol. The method uses an IMF molecular sieve with a large pore structure as a catalyst, which is beneficial to improving the trimethylolbenzene conversion rate, durene selectivity and tetramethylolbenzene selectivity, and reducing the by-product C 6 -C 8 Aromatic selectivity.

[0006] In order to achieve the above object, the present invention provides a method for alkylating trimethylol and methanol to synthesize durene, the method comprising: contacting trimethylol and methanol under alkylation reaction conditions and in the presence of a catalyst; wherein the catalyst comprises an IMF structure molecular sieve, and the total pore volume of the IMF structure molecular sieve is 0.2 to 0.4 cm 3 ·g -1 , the mesopore volume is 0.08~0.3cm 3 ·g -1 .

[0007] Optionally, the alkylation reaction conditions include: in a fixed bed reactor, the unsymmetrical trimethylolbenzene and methanol are contacted with the catalyst under gas phase reaction conditions, the gas phase reaction temperature is 280-400° C., preferably 300-360° C.; the time is 10-60 h, preferably 20-45 h; the pressure is 0.5-1.2 MPa, preferably 0.6-1.0 MPa; the mass space velocity of unsymmetrical trimethylolbenzene is 1.5-1.6 h -1 , preferably 1.52~1.58h -1 ; Wherein, the feed molar ratio of the unsymmetrical trimethylolbenzene to methanol is (0.5-3):1, preferably (1-2):1.

[0008] Optionally, the total pore volume of the IMF structure molecular sieve is 0.23 to 0.4 cm 3 ·g -1 , the mesopore volume is 0.15~0.24cm 3 ·g -1 , the total specific surface area is 350~420m 2 ·g -1 , preferably 360~400m 2 g -1 .

[0009] Optionally, the IMF structure molecular sieve is NH 3 The acid amount of the medium-strong acid measured by the -TPD method accounts for 40-55% of the total acid amount, preferably 45-50%; the ratio of the B acid amount to the L acid amount measured by the pyridine adsorption infrared method at 200°C is 2-7, preferably 4-6; the ratio of the B acid amount to the L acid amount measured by the pyridine adsorption infrared method at 350°C is 3-6, preferably 4-5.5; preferably, the IMF structure molecular sieve is NH 3 The total acid content measured by the TPD method is 1000 to 2200 μmol / g, preferably 1300 to 2000 μmol / g.

[0010] Optionally, the IMF structured molecular sieve is composed of SiO 2 Silicon and Al 2 O3 The molar ratio of aluminum element is 20-40, preferably 25-35; the relative crystallinity is 70-110%, preferably 80-100%; the IMF structure molecular sieve is IM-5 molecular sieve, preferably H-IM-5 molecular sieve.

[0011] Optionally, the method further comprises preparing the IMF structure molecular sieve by the following steps:

[0012] (1) mixing a silicon source, an aluminum source, an alkali source, a structure directing agent, water and an optional mineralizer to obtain a first mixture; subjecting the first mixture to a first stage of hydrothermal crystallization and a second stage of hydrothermal crystallization to obtain a gel molecular sieve; wherein the temperature of the first stage of hydrothermal crystallization is lower than the temperature of the second stage of hydrothermal crystallization; the silicon source is SiO 2 The aluminum source is Al 2 O 3 The alkali source is in the form of alkali metal oxide M 2 O, the structure directing agent is represented by SDR, SiO 2 With Al 2 O 3 The molar ratio of M is 35-70. 2 O and SiO 2 The molar ratio of SDR to SiO is 0.15-0.25. 2 The molar ratio of water to SiO is 0.08-0.14. 2 The molar ratio of mineralizer to SiO is 10-20. 2 The molar ratio of is 0 to 0.05; the absolute value of the temperature difference between the first hydrothermal crystallization and the second hydrothermal crystallization is 15 to 55°C;

[0013] (2) flocculating and mixing the gel molecular sieve with a first ammonium salt solution, and performing a first drying and a first calcination on the obtained second mixture to obtain a solid molecular sieve; the weight ratio of the gel molecular sieve to the first ammonium salt solution is 1:(10-50);

[0014] (3) contacting the solid molecular sieve with a second ammonium salt solution to perform ion exchange, and then performing a second drying and a second calcination; the weight ratio of the solid molecular sieve to the second ammonium salt solution is 1:(10-40).

[0015] Optionally, in step (1), the silicon source is SiO 2 The aluminum source is Al 2 O 3 The alkali source is in the form of alkali metal oxide M 2 O, the structure directing agent is represented by SDR, SiO 2 With Al 2 O3 The molar ratio of M is 40-60; 2 O and SiO 2 The molar ratio of SDR to SiO is 0.18-0.24; 2 The molar ratio of water to SiO is 0.1 to 0.12; 2 The molar ratio of mineralizer to SiO is 11-14; 2 The molar ratio is 0.01-0.03; the absolute value of the temperature difference between the first hydrothermal crystallization and the second hydrothermal crystallization is 15-35°C; preferably, the temperature of the first hydrothermal crystallization is 120-160°C, preferably 140-160°C; the time is 12-96h, preferably 24-48h; the temperature of the second hydrothermal crystallization is 150-180°C, preferably 160-180°C; the time is 72-192h, preferably 96-144h.

[0016] Optionally, in step (1), the silicon source is selected from one or more of solid silica gel, silica sol, tetraethyl orthosilicate and white carbon black, preferably solid silica gel; the aluminum source is selected from one or more of sodium aluminate, aluminum trichloride, aluminum sulfate and aluminum sol, preferably sodium aluminate; the alkali source is selected from one or more of sodium hydroxide, potassium hydroxide, sodium oxide and potassium oxide, preferably sodium hydroxide; the structure directing agent is selected from at least one of the structures shown in the following formula (1):

[0017]

[0018] Where R 1 ~R 2 are independently selected from alkyl groups having 1 to 4 carbon atoms, preferably, R 1 ~R 2 Each is independently selected from one or more of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl, preferably methyl or ethyl; n represents -CH 2 -, n is any integer from 1 to 10; X 1 ~X 2 Each is independently selected from OH, Br, Cl or I; the mineralizer is selected from one or more of sodium fluoride, sodium chloride, sodium bromide and ammonium fluoride.

[0019] Optionally, in step (2), the weight ratio of the gel molecular sieve to the first ammonium salt solution is 1:(10-30); the temperature of the first drying is 80-150°C, preferably 100-120°C; the time is 8-12h, preferably 8-10h; the temperature of the first calcination is 400-600°C, preferably 450-550°C; the time is 2-6h, preferably 3-5h; the concentration of the first ammonium salt solution is 10-30% by weight, and the first ammonium salt solution is selected from one or more of ammonium chloride solution, ammonium nitrate solution and ammonium sulfate solution.

[0020] Optionally, in step (3), the weight ratio of the solid molecular sieve to the second ammonium salt solution is 1:(20-30); the temperature of the ion exchange is 60-100°C, preferably 65-80°C; the time is 2-8h, preferably 4-8h; the temperature of the second drying is 80-150°C, preferably 80-120°C; the time is 8-12h, preferably 8-10h; the temperature of the second calcination is 400-600°C, preferably 450-550°C; the time is 2-6h, preferably 3-5h; the concentration of the second ammonium salt solution is 10-30% by weight, and the second ammonium salt solution is selected from one or more of ammonium chloride solution, ammonium nitrate solution and ammonium sulfate solution.

[0021] Through the above technical scheme, the present disclosure provides a method for synthesizing durene by alkylation of trimethylbenzene with methanol. The method uses an IMF structure molecular sieve with a larger pore structure as a catalyst. Compared with the ZSM-5 molecular sieve, the IMF structure molecular sieve is composed of two two-dimensional pore systems connected by a three-dimensional pore (along the

[010] crystal plane), and a larger cavity is generated at the intersection of the pores, which is beneficial to improve the distribution of raw materials and products, increase the alkylation reaction rate of trimethylbenzene and methanol, and increase the product C 10 The diffusion rate of aromatics is increased, thereby improving the conversion rate of trimethylolbenzene, the selectivity of durene and tetramethylbenzene, and reducing the by-product C 6 -C 8 Aromatic selectivity.

[0022] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0024] Figure 1 is the XRD pattern of catalyst 1 prepared in Preparation Example 1;

[0025] Figure 2 is the NH of the catalyst 1 prepared in Preparation Example 1 and the comparative catalyst 1 prepared in Preparation Comparative Example 1. 3 -TPD spectrum;

[0026] Figure 3 It is the Py-IR spectra (200° C.) of Catalyst 1 prepared in Preparation Example 1 and Comparative Catalyst 1 prepared in Preparation Comparative Example 1. DETAILED DESCRIPTION

[0027] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0028] The present invention discloses a method for preparing durene by alkylation reaction of partial trimethylbenzene and methanol, the method comprising: contacting the partial trimethylbenzene with methanol under alkylation reaction conditions and in the presence of a catalyst; wherein the catalyst comprises an IMF structure molecular sieve, and the total pore volume of the IMF structure molecular sieve is 0.2-0.4 cm 3 ·g -1 , the mesopore volume is 0.08~0.3cm 3 ·g -1 .

[0029] The method provided by the present invention uses an IMF structure molecular sieve with a larger pore structure as a catalyst. Compared with the ZSM-5 molecular sieve, the IMF structure molecular sieve is composed of two two-dimensional pore systems, which are connected by a three-dimensional pore (along the

[010] crystal plane), and a larger cavity is generated at the intersection of the pores, which is beneficial to improve the distribution of raw materials and products, increase the alkylation reaction rate of trimethylolbenzene and methanol, and increase the product C 10 The diffusion rate of aromatics is increased, thereby improving the conversion rate of trimethylolbenzene, the selectivity of durene and tetramethylbenzene, and reducing the by-product C 6 -C 8 Aromatic selectivity.

[0030] In one embodiment of the present disclosure, the alkylation reaction conditions include: in a fixed bed reactor, the unsymmetrical trimethylolbenzene and methanol are contacted with the catalyst under gas phase reaction conditions, the gas phase reaction temperature is 280-400°C, preferably 300-360°C; the time is 10-60h, preferably 20-45h; the pressure is 0.5-1.2MPa, preferably 0.6-1.0MPa; the mass space velocity of unsymmetrical trimethylolbenzene is 1.5-1.6h -1 , preferably 1.52~1.58h -1; Wherein, the feed molar ratio of the trimethylolbenzene to methanol is (0.5-3):1, preferably (1-2):1. In the above embodiment, by selecting the preferred alkylation reaction conditions and feed ratio, it is beneficial for trimethylolbenzene and methanol to fully react, and further improve the trimethylolbenzene conversion rate and product selectivity.

[0031] In one embodiment of the present disclosure, the total pore volume of the IMF structure molecular sieve is 0.23-0.4 cm 3 ·g -1 , the mesopore volume is 0.15~0.24cm 3 ·g -1 , the total specific surface area is 350~420m 2 ·g -1 , preferably 360~400m 2 g -1 In the above embodiment, by selecting an IMF structure molecular sieve with a preferred pore structure and total specific surface area, it is beneficial to further increase the alkylation reaction rate and increase the diffusion rate of the product.

[0032] In one embodiment of the present disclosure, the IMF structure molecular sieve is NH 3 -TPD method measured the acid amount of medium-strong acid accounts for 40-55% of the total acid amount, preferably 45-50%; the ratio of B acid to L acid measured by pyridine adsorption infrared method at 200°C is 2-7, preferably 4-6; the ratio of B acid to L acid measured by pyridine adsorption infrared method at 350°C is 3-6, preferably 4-5.5. In a preferred embodiment, the IMF structure molecular sieve is NH 3 -The total acid content measured by the TPD method is 1000-2200 μmol / g, preferably 1300-2000 μmol / g. In the above embodiment, the IMF structure molecular sieve has a higher acid content and acid strength, and a more suitable B / L value, which is conducive to improving the conversion rate of trimethylol and product selectivity.

[0033] In the present disclosure, a weak acid refers to a 3 Programmed temperature desorption (NH 3 -TPD) corresponds to an acid with a desorption temperature of 100 to 300 °C. A medium-strong acid refers to an acid that is 3 Programmed temperature desorption (NH 3 -TPD) corresponds to an acid with a desorption temperature of 300 to 500 °C. A strong acid is an acid that is 3 Programmed temperature desorption (NH 3 -TPD) corresponds to an acid with a desorption temperature of 500-600°C, and the total acid refers to the sum of weak acid, medium-strong acid and strong acid.

[0034] In one embodiment of the present disclosure, the IMF structured molecular sieve is composed of SiO 2 Silicon and Al 2 O 3 The molar ratio of aluminum element is 20-40, preferably 25-35; the relative crystallinity is 70-110%, preferably 80-100%; the IMF structure molecular sieve is IM-5 molecular sieve, preferably H-IM-5 molecular sieve. In the above embodiment, the IMF structure molecular sieve has a suitable silicon-aluminum ratio and relative crystallinity.

[0035] In one embodiment of the present disclosure, the method further comprises preparing the IMF structure molecular sieve by the following steps:

[0036] (1) mixing a silicon source, an aluminum source, an alkali source, a structure directing agent, water and an optional mineralizer to obtain a first mixture; subjecting the first mixture to a first stage of hydrothermal crystallization and a second stage of hydrothermal crystallization to obtain a gel molecular sieve; wherein the temperature of the first stage of hydrothermal crystallization is lower than the temperature of the second stage of hydrothermal crystallization; the silicon source is SiO 2 The aluminum source is Al 2 O 3 The alkali source is in the form of alkali metal oxide M 2 O, the structure directing agent is represented by SDR, SiO 2 With Al 2 O 3 The molar ratio of M is 35-70. 2 O and SiO 2 The molar ratio of SDR to SiO is 0.15-0.25. 2 The molar ratio of water to SiO is 0.08-0.14. 2 The molar ratio of mineralizer to SiO is 10-20. 2 The molar ratio of is 0 to 0.05; the absolute value of the temperature difference between the first hydrothermal crystallization and the second hydrothermal crystallization is 15 to 55°C;

[0037] (2) flocculating and mixing the gel molecular sieve with a first ammonium salt solution, and performing a first drying and a first calcination on the obtained second mixture to obtain a solid molecular sieve; the weight ratio of the gel molecular sieve to the first ammonium salt solution is 1:(10-50);

[0038] (3) contacting the solid molecular sieve with a second ammonium salt solution to perform ion exchange, and then performing a second drying and a second calcination; the weight ratio of the solid molecular sieve to the second ammonium salt solution is 1:(10-40).

[0039] In the above embodiment, a two-stage hydrothermal crystallization method is used to prepare a pure phase IMF structure molecular sieve, which has a larger pore structure and more intercrystalline mesopores, which is beneficial to improve the distribution of raw materials and products and obtain higher trimethylolbenzene conversion rate, tetramethylolene selectivity and tetramethylbenzene selectivity.

[0040] In one embodiment of the present disclosure, in step (1), the silicon source is SiO 2 The aluminum source is Al 2 O 3 The alkali source is in the form of alkali metal oxide M 2 O, the structure directing agent is represented by SDR, SiO 2 With Al 2 O 3 The molar ratio of M is 40-60; 2 O and SiO 2 The molar ratio of SDR to SiO is 0.18-0.24; 2 The molar ratio of water to SiO is 0.1 to 0.12; 2 The molar ratio of mineralizer to SiO is 11-14; 2 The molar ratio is 0.01-0.03; the absolute value of the temperature difference between the first hydrothermal crystallization and the second hydrothermal crystallization is 15-35°C; preferably, the temperature of the first hydrothermal crystallization is 120-160°C, preferably 140-160°C; the time is 12-96h, preferably 24-48h; the temperature of the second hydrothermal crystallization is 150-180°C, preferably 160-180°C; the time is 72-192h, preferably 96-144h.

[0041] In one embodiment of the present disclosure, in step (1), the silicon source is selected from one or more of solid silica gel, silica sol, tetraethyl orthosilicate and white carbon black, preferably solid silica gel; the aluminum source is selected from one or more of sodium aluminate, aluminum trichloride, aluminum sulfate and aluminum sol, preferably sodium aluminate; the alkali source is selected from one or more of sodium hydroxide, potassium hydroxide, sodium oxide and potassium oxide, preferably sodium hydroxide; the structure directing agent is selected from at least one of the structures shown in the following formula (1): Where R 1 ~R 2 are independently selected from alkyl groups having 1 to 4 carbon atoms, preferably, R 1 ~R 2 Each is independently selected from one or more of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl, preferably methyl or ethyl; n represents -CH 2 -, n is any integer from 1 to 10; X 1~X 2 Each is independently selected from OH, Br, Cl or I; the mineralizer is selected from one or more of sodium fluoride, sodium chloride, sodium bromide and ammonium fluoride.

[0042] In one embodiment of the present disclosure, in step (2), the weight ratio of the gel molecular sieve to the first ammonium salt solution is 1: (10-30); the temperature of the first drying is 80-150°C, preferably 100-120°C; the time is 8-12h, preferably 8-10h; the temperature of the first roasting is 400-600°C, preferably 450-550°C; the time is 2-6h, preferably 3-5h; the concentration of the first ammonium salt solution is 10-30% by weight, and the first ammonium salt solution is selected from one or more of ammonium chloride solution, ammonium nitrate solution and ammonium sulfate solution. In the above embodiment, the first ammonium salt solution is used to flocculate and mix the gel molecular sieve, which is beneficial to the solid-liquid separation and charge balance of the gel, and promotes the next step of ion exchange.

[0043] In one embodiment of the present disclosure, in step (3), the weight ratio of the solid molecular sieve to the second ammonium salt solution is 1: (20-30); the temperature of the ion exchange is 60-100°C, preferably 65-80°C; the time is 2-8h, preferably 4-8h; the temperature of the second drying is 80-150°C, preferably 80-120°C; the time is 8-12h, preferably 8-10h; the temperature of the second roasting is 400-600°C, preferably 450-550°C; the time is 2-6h, preferably 3-5h; the concentration of the second ammonium salt solution is 10-30% by weight, and the second ammonium salt solution is selected from one or more of ammonium chloride solution, ammonium nitrate solution and ammonium sulfate solution. In the above embodiment, the solid molecular sieve is ion exchanged with the second ammonium salt solution, which is conducive to the formation of a hydrogen-type molecular sieve.

[0044] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited thereby.

[0045] In the embodiments and comparative examples of the present disclosure, a Quanta 200F scanning electron microscope (SEM) produced by FEI Company was used for microscopic morphology analysis, and the operating voltage of the SEM was 20 kV; a Japan Hitachi S-4800 type instrument was used to test the average particle size of the catalyst.

[0046] The crystallinity of the molecular sieve is determined by the RIPP 146-90 standard method. The RIPP standard method mentioned here can be found in "Petrochemical Analysis Methods", edited by Yang Cuiding et al., 1990 edition.

[0047] The chemical composition of the molecular sieve was determined by using a 3013 X-ray fluorescence spectrometer produced by Rigaku Corporation of Japan, and the silicon-aluminum ratio of the molecular sieve was calculated. The target was tungsten, the excitation voltage was 40 kV, and the excitation current was 50 mA.

[0048] The specific surface area and pore volume were measured using the AS-3 and AS-6 static nitrogen adsorption instruments produced by Quantachrome Instruments. The specific method was as follows: the sample was placed in a sample treatment system and vacuumed to 1.33×10 -2 Pa, keep the temperature and pressure for 4 hours, purify the sample; test the purified sample at different pressure ratios P / P at a liquid nitrogen temperature of -196°C 0 The adsorption and desorption of nitrogen under the conditions were obtained. 2 Adsorption-desorption isotherm curve, the specific surface area of ​​the sample is calculated using the BET method, the mesoporous volume of the sample is calculated using the t-plot method, and the specific pressure P / P is taken. 0 = 0.98 or less is the total pore volume of the sample.

[0049] The acidity and total acidity of medium-strong acid are NH 3 The measurement was carried out by the AutochemⅡ2920 programmed temperature desorption instrument of Micromeritics, USA. The specific method was as follows: 0.2 g of the sample to be tested was weighed and loaded into a sample tube, which was placed in a thermal conductivity cell heating furnace. He gas was used as the carrier gas (50 mL / min), and the temperature was raised to 600°C at a rate of 20°C / min. The impurities adsorbed on the catalyst surface were purged for 60 min, and then the temperature was lowered to 100°C, kept constant for 30 min, and switched to NH 3 -He mixed gas (10.02% NH 3 +89.98% He) for 30 minutes, and then continue to purge with He gas for 90 minutes until the baseline is stable to desorb the physically adsorbed ammonia; the temperature is increased to 600°C at a heating rate of 10°C / min for desorption, and maintained for 30 minutes, and the desorption is completed; a TCD detector is used to detect the change of gas components, and the instrument automatically integrates the total acid content.

[0050] The acid content of B acid and L acid was measured by 2,6-di-tert-butylpyridine adsorption infrared acid method using a Vertex 70 instrument produced by Bruker Instruments. The specific method is as follows: the catalyst is pressed into a 10 mg / cm 2 The slice was placed in a CaF 2 In the infrared cell of the window, first evacuate at 400°C, then reduce to 150°C to adsorb 2,6-di-tert-butylpyridine for 15 minutes, then evacuate for 1 hour, reduce to room temperature to collect spectra, and calculate the acid amount of B acid and the acid amount of L acid. See Applied Catalysis A: General, 294, 2005: 92.

[0051] The gas chromatographic peak area normalization method was used to calculate the conversion rate of trimethylolbenzene, durene selectivity, tetramethylol selectivity and C 6 -C 8 Aromatic selectivity, the test method is as follows: the carrier gas is nitrogen, the detector is FID, the column temperature is 80℃, the injector temperature is 260℃, and the detector temperature is 250℃. The initial temperature of the program temperature rise is 0℃, the holding time is 0min, and the heating rate is 3℃ / min; the final temperature is 50℃, and the holding time is 20min. The injection volume is 0.2μL.

[0052] Preparation Example 1

[0053] This preparation example 1 is used to illustrate the preparation of IMF structure molecular sieve:

[0054] (1) 6.44 g of solid silica gel (silicon source, SiO 2 93.2% by mass), 3.15g sodium aluminate solution (aluminum source, with Al 2 O 3 8.17% by mass, 15.6% by mass as NaOH), 1.11 g sodium hydroxide (alkali source, alkali metal oxide M 2 O, wherein the mass fraction of sodium hydroxide is 96%), 8.15g of structure directing agent solution (mass fraction is 58.9%, the structural formula is That is R 1 and R 2 is methyl, n is 5, X is Br, the structure directing agent is represented by SDR, and the molecular weight is 400) and 19.00g of water are added to the Teflon liner in the order of liquid first and solid later, and mixed evenly to form a first mixture. The molar ratio of each component in the first mixture is: SiO 2 / Al 2 O 3 =40, Na 2 O / SiO 2 =0.2, SDR / SiO 2 =0.12, H 2 O / SiO 2 =14;

[0055] (2) The first mixture is placed in a high-pressure reactor with a volume of 45 ml, and two hydrothermal crystallizations are carried out in a homogeneous reactor. The temperature of the first hydrothermal crystallization is 160°C and the time is 48 hours; the temperature of the second hydrothermal crystallization is 175°C and the time is 96 hours. The obtained gel molecular sieve is flocculated and mixed with a 30% ammonium chloride solution (the first ammonium salt solution) by mass, and the weight ratio of the gel molecular sieve to the ammonium chloride solution is 1:20; the filtered solid is placed in a 110°C drying oven for the first drying for 8 hours, and after grinding, it is placed in a 550°C muffle furnace for the first roasting for 4 hours to remove the structure directing agent to obtain a solid molecular sieve;

[0056] (3) The solid molecular sieve was mixed with a 10% ammonium chloride solution (second ammonium salt solution) for ion exchange. The weight ratio of the solid molecular sieve to the ammonium chloride solution was 1:20. The number of ion exchanges was 3 times, the exchange temperature was 80°C, and the time was 4 hours. After 3 centrifugations until the pH value was neutral, the centrifugal speed was 5000r / min, and the time was 15 minutes, an ammonium type molecular sieve was obtained. The ammonium type molecular sieve was placed in a 120°C drying oven for a second drying for 10 hours, and after grinding, it was placed in a 550°C muffle furnace for a second calcination for 3 hours to obtain H-IM-5 molecular sieve, i.e., IMF structure molecular sieve; the molecular sieve was pressed into sheets at a pressure of 20MPa, and particles of 20 to 40 mesh (i.e., an average particle size of 0.63 to 0.85mm) were screened as catalyst 1, recorded as I-1. Its physicochemical properties are shown in Tables 1 and 2.

[0057] Preparation Example 2

[0058] This preparation example 2 is used to illustrate the preparation of IMF structure molecular sieve:

[0059] The same as Preparation Example 1, the only difference is that the molar ratio of each component in the first mixture is: SiO 2 / Al 2 O 3 =40, Na 2 O / SiO 2 =0.185, SDR / SiO 2 =0.12, H 2 O / SiO 2 = 14, that is, 60g solid silica gel (silicon source, SiO 2 Calculated), 29.62g sodium aluminate (aluminum source, as Al 2 O 3 ), 9.16 g sodium hydroxide (alkali source, in the form of alkali metal oxide M 2 O), 76.05g structure directing agent (structural formula The first mixture was prepared by adding 177.06 g of water (SDR) and 177.06 g of water to the Teflon liner in the order of liquid first and solid later, and mixing them evenly. Finally, catalyst 2 was obtained, which was designated as I-2. Its physical and chemical properties are shown in Tables 1 and 2.

[0060] Preparation Example 3

[0061] This preparation example 3 is used to illustrate the preparation of IMF structure molecular sieve:

[0062] The same as Preparation Example 1, the only difference is that the molar ratio of each component in the first mixture is: SiO 2 / Al 2 O 3 =40, Na 2 O / SiO 2 =0.185, SDR / SiO 2 =0.12, mineralizer / SiO 2 0.013, H 2 O / SiO 2 = 14, that is, 9.67g solid silica gel (silicon source, SiO 2 ), 4.87 g sodium aluminate (aluminum source, in terms of Al 2 O 3 ), 1.57 g sodium hydroxide (alkali source, in the form of alkali metal oxide M 2 O), 12.23g structure directing agent (structural formula 28.62g of water and 0.082g of sodium fluoride (mineralizer) were added to the Teflon liner in the order of liquid first and solid later, and mixed evenly to form a first mixture. Finally, catalyst 3 was obtained. It is marked as I-3. Its physical and chemical properties are shown in Tables 1 and 2.

[0063] Preparation Example 4

[0064] This preparation example 4 is used to illustrate the preparation of IMF structure molecular sieve:

[0065] The same as Preparation Example 1, the only difference is that the solid molecular sieve is ion exchanged with a 30% by mass ammonium chloride solution (second ammonium salt solution), and the weight ratio of the solid molecular sieve to the ammonium chloride solution is 1:50. Finally, catalyst 4 is obtained. It is recorded as I-4. Its physical and chemical properties are shown in Tables 1 and 2.

[0066] Preparation Example 5

[0067] This preparation example 5 is used to illustrate the preparation of IMF structure molecular sieve:

[0068] The same as Preparation Example 1, the only difference is that the gel molecular sieve is flocculated and mixed with a 30% by mass ammonium chloride solution (first ammonium salt solution), and the weight ratio of the gel molecular sieve to the ammonium chloride solution is 1:50. Finally, catalyst 5 is obtained. It is recorded as I-5. Its physical and chemical properties are shown in Tables 1 and 2.

[0069] Preparation Example 6

[0070] This preparation example 6 is used to illustrate the preparation of IMF structure molecular sieve:

[0071] The same as Preparation Example 1, the only difference is that the molar ratio of the components in the first mixture is: SiO 2 / Al 2 O 3 =70, Na 2 O / SiO 2 =0.185, SDR / SiO 2 =0.12, mineralizer / SiO 2 0.013, H 2 O / SiO 2 = 14, that is, 16.92g solid silica gel (silicon source, SiO 2 ), 4.69 g sodium aluminate (aluminum source, in terms of Al 2 O 3 ), 3.16 g sodium hydroxide (alkali source, in the form of alkali metal oxide M 2 O), 21.42g structure directing agent (structural formula: 52.54 g of water and 0.14 g of sodium fluoride (mineralizer) were added to the Teflon liner in the order of liquid first and solid later, and mixed evenly to form a first mixture. Finally, catalyst 6 was obtained, which was recorded as I-6. Its physical and chemical properties are shown in Tables 1 and 2.

[0072] Preparation Example 7

[0073] This preparation example 7 is used to illustrate the preparation of IMF structure molecular sieve:

[0074] The same as Preparation Example 1, the only difference is that in step (2), the temperature of the first hydrothermal crystallization is 125°C, and the temperature of the second hydrothermal crystallization is 155°C, and finally catalyst 7 is obtained. It is denoted as I-7. Its physical and chemical properties are shown in Tables 1-2.

[0075] Preparation Comparative Example 1

[0076] This preparation comparative example 1 is used to illustrate the preparation of H-ZSM-5 molecular sieve:

[0077] The ZSM-5 molecular sieve powder (Changling Branch of Sinopec Catalyst Company) with a silicon-aluminum ratio of 49 was ion exchanged with a 10% ammonium chloride solution by mass. The weight ratio of ZSM-5 molecular sieve powder to ammonium chloride solution was 10, the number of exchanges was 3, the exchange temperature was 80°C, and the time was 4h. After 3 centrifugations until the pH value was neutral, the speed was 5000r / min, and the time was 15min, a gel molecular sieve was obtained. The gel molecular sieve was placed in a 120°C drying oven for 8h, ground and placed in a 550°C muffle furnace for calcination for 3h to obtain H-ZSM-5 molecular sieve. The molecular sieve was pressed into sheets under a pressure of 20MPa, and particles of 20-40 mesh (i.e., an average particle size of 0.63-0.85mm) were screened as comparative catalyst 1, denoted as Z-1, and its physicochemical properties are shown in Tables 1-2.

[0078] Preparation Comparative Example 2

[0079] The same as the preparation of comparative example 1, the only difference is that the silicon-aluminum ratio of the ZSM-5 molecular sieve powder is 45, the mass fraction of ammonium chloride is 20%, the weight ratio of the ZSM-5 molecular sieve powder to the ammonium chloride solution is 20, the exchange time is 3h, the centrifugal speed is 4000r / min, and the time is 20min. Finally, comparative catalyst 2 is obtained, recorded as Z-2, and its physical and chemical properties are shown in Tables 1 and 2.

[0080] Preparation Comparative Example 3

[0081] The same as the preparation of comparative example 1, the only difference is that the silicon-aluminum ratio of the ZSM-5 molecular sieve powder is 59, the mass fraction of ammonium chloride is 30%, the weight ratio of the ZSM-5 molecular sieve powder to the ammonium chloride solution is 30, the exchange time is 5h, the centrifugal speed is 3000r / min, and the time is 30min. Finally, comparative catalyst 3 is obtained, denoted as Z-3, and its physical and chemical properties are shown in Tables 1 and 2.

[0082] Preparation Comparative Example 4

[0083] The same as the preparation of comparative example 1, the only difference is that the silicon-aluminum ratio of the ZSM-5 molecular sieve powder is 35, the mass fraction of ammonium chloride is 30%, the weight ratio of the ZSM-5 molecular sieve powder to the ammonium chloride solution is 30, the ion exchange temperature is 85°C, and the exchange time is 2h. Finally, comparative catalyst 4 is obtained, denoted as Z-4, and its physicochemical properties are shown in Tables 1 and 2.

[0084] Preparation Comparative Example 5

[0085] The same as the preparation of comparative example 1, the only difference is that the silicon-aluminum ratio of the ZSM-5 molecular sieve powder is 25, the mass fraction of ammonium chloride is 30%, the weight ratio of the ZSM-5 molecular sieve powder to the ammonium chloride solution is 30, the ion exchange temperature is 90°C, the exchange time is 6h, the centrifugal speed is 3000r / min, and the time is 30min. Finally, comparative catalyst 5 is obtained, denoted as Z-5, and its physical and chemical properties are shown in Tables 1 and 2.

[0086] Table 1

[0087]

[0088] Table 2

[0089]

[0090]

[0091] The following examples and comparative examples are used to illustrate the method of catalyzing the alkylation reaction of trimethylolbenzene with methanol using different catalysts.

[0092] Example 1

[0093] 2 g of I-1 was loaded into a fixed bed reactor, and trimethylbenzene and methanol were added as reaction raw materials. The reaction conditions were as follows: reaction temperature was 360 °C, reaction pressure was 0.8 MPa, reaction time was 20 h, nitrogen flow rate was 300 ml / min, trimethylbenzene to methanol feed molar ratio was 2:1, and the mass space velocity of trimethylbenzene was 1.56 h -1 , all components were analyzed by GC online. The evaluation results are shown in Table 3. The conversion rate of trimethylol, durene selectivity, tetramethylol selectivity and C 6 -C 8 The aromatic selectivity is calculated according to the following formulas (1) to (4):

[0094]

[0095]

[0096]

[0097]

[0098] Embodiments 2 to 7

[0099] The alkylation reaction of trimethylolbenzene and methanol was carried out according to the method and reaction conditions of Example 1. The alkylation reaction was catalyzed by the catalysts prepared in Preparation Examples 2 to 7. The reaction results are shown in Table 3.

[0100] Comparative Examples 1 to 5

[0101] The alkylation reaction of trimethylol and methanol was carried out according to the method and reaction conditions of Example 1. The alkylation reaction was catalyzed by the comparative catalysts prepared in Preparation Comparative Examples 1 to 7. The reaction results are shown in Table 3.

[0102] Table 3

[0103]

[0104] From the results in Tables 1 to 3 above, it can be seen that the IMF structure molecular sieve provided by the present disclosure has a larger pore structure, including a larger total pore volume and a larger mesopore volume, which is beneficial to improving the alkylation reaction rate and the product diffusion rate, so that when it is used as a catalyst for the alkylation reaction of unsymmetrical trimethylbenzene and methanol, it can improve the unsymmetrical trimethylbenzene conversion rate, durene selectivity and tetramethylbenzene selectivity, and reduce the by-product C 6 -C 8 Aromatic hydrocarbon selectivity: Comparative Examples 1 to 5 use ZSM-5 molecular sieve as a catalyst, and when used for the alkylation reaction of trimethylolbenzene and methanol, the conversion rate of trimethylolbenzene and the selectivity of durene are low, and the selectivity of by-products is high.

[0105] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0106] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0107] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for synthesizing durene by alkylation of trimethylolbenzene and methanol, characterized in that: The method comprises: contacting trimethylol with methanol under alkylation reaction conditions and in the presence of a catalyst; wherein the catalyst comprises an IMF structure molecular sieve, and the total pore volume of the IMF structure molecular sieve is 0.2 to 0.4 cm 3 ·g -1 , the mesopore volume is 0.08~0.3cm 3 ·g -1 .

2. The method according to claim 1, characterized in that The alkylation reaction conditions include: in a fixed bed reactor, making the unsymmetrical trimethylbenzene and methanol contact with the catalyst under gas phase reaction conditions, the gas phase reaction temperature is 280-400° C., preferably 300-360° C.; the time is 10-60 hours, preferably 20-45 hours; the pressure is 0.5-1.2 MPa, preferably 0.6-1.0 MPa; the mass space velocity of unsymmetrical trimethylbenzene is 1.5-1.6 h -1 , preferably 1.52~1.58h -1 ; The feed molar ratio of the trimethylolbenzene to methanol is (0.5-3):1, preferably (1-2):

1.

3. The method according to claim 1, characterized in that The total pore volume of the IMF structure molecular sieve is 0.23 to 0.4 cm 3 ·g -1 , the mesopore volume is 0.15~0.24cm 3 ·g -1 , the total specific surface area is 350~420m 2 ·g -1 , preferably 360~400m 2 g -1 .

4. The method according to claim 1, characterized in that: The acid amount of the medium-strong acid of the IMF structure molecular sieve measured by the NH3-TPD method accounts for 40-55% of the total acid amount, preferably 45-50%; the ratio of the B acid amount to the L acid amount measured by the pyridine adsorption infrared method at 200°C is 2-7, preferably 4-6; the ratio of the B acid amount to the L acid amount measured by the pyridine adsorption infrared method at 350°C is 3-6, preferably 4-5.5; Preferably, the total acid content of the IMF structure molecular sieve measured by NH3-TPD method is 1000-2200 μmol / g, preferably 1300-2000 μmol / g.

5. The method according to claim 1, characterized in that: The molar ratio of silicon element calculated as SiO2 to aluminum element calculated as Al2O3 in the IMF structure molecular sieve is 20-40, preferably 25-35; the relative crystallinity is 70-110%, preferably 80-100%; the IMF structure molecular sieve is IM-5 molecular sieve, preferably H-IM-5 molecular sieve.

6. The method according to claim 1, characterized in that The method further comprises preparing the IMF structure molecular sieve by the following steps: (1) mixing a silicon source, an aluminum source, an alkali source, a structure directing agent, water and an optional mineralizer to obtain a first mixture; subjecting the first mixture to a first hydrothermal crystallization and a second hydrothermal crystallization to obtain a gel molecular sieve; wherein the temperature of the first hydrothermal crystallization is lower than the temperature of the second hydrothermal crystallization; the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, the alkali source is calculated as an alkali metal oxide M2O, the structure directing agent is expressed as SDR, the molar ratio of SiO2 to Al2O3 in the first mixture is 35-70, the molar ratio of M2O to SiO2 is 0.15-0.25, the molar ratio of SDR to SiO2 is 0.08-0.14, the molar ratio of water to SiO2 is 10-20, and the molar ratio of the mineralizer to SiO2 is 0-0.05; the absolute value of the temperature difference between the first hydrothermal crystallization and the second hydrothermal crystallization is 15-55°C; (2) flocculating and mixing the gel molecular sieve with a first ammonium salt solution, and performing a first drying and a first calcination on the obtained second mixture to obtain a solid molecular sieve; the weight ratio of the gel molecular sieve to the first ammonium salt solution is 1:(10-50); (3) contacting the solid molecular sieve with a second ammonium salt solution to perform ion exchange, and then performing a second drying and a second calcination; the weight ratio of the solid molecular sieve to the second ammonium salt solution is 1:(10-40).

7. The method according to claim 6, characterized in that In step (1), the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, the alkali source is calculated as alkali metal oxide M2O, and the structure directing agent is expressed as SDR. In the first mixture, the molar ratio of SiO2 to Al2O3 is 40-60; the molar ratio of M2O to SiO2 is 0.18-0.24; the molar ratio of SDR to SiO2 is 0.1-0.12; the molar ratio of water to SiO2 is 11-14; and the molar ratio of mineralizer to SiO2 is 0.01-0.03; The absolute value of the temperature difference between the first hydrothermal crystallization and the second hydrothermal crystallization is 15-35°C; preferably, the temperature of the first hydrothermal crystallization is 120-160°C, preferably 140-160°C; the time is 12-96h, preferably 24-48h; the temperature of the second hydrothermal crystallization is 150-180°C, preferably 160-180°C; the time is 72-192h, preferably 96-144h.

8. The method according to claim 6, characterized in that In step (1), the silicon source is selected from one or more of solid silica gel, silica sol, tetraethyl orthosilicate and white carbon black, preferably solid silica gel; The aluminum source is selected from one or more of sodium aluminate, aluminum chloride, aluminum sulfate and aluminum sol, preferably sodium aluminate; The alkali source is selected from one or more of sodium hydroxide, potassium hydroxide, sodium oxide and potassium oxide, preferably sodium hydroxide; The structure directing agent is selected from at least one of the structures shown in the following formula (1): wherein R1-R2 are each independently selected from an alkyl group having 1 to 4 carbon atoms, preferably, R1-R2 are each independently selected from one or more of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl, preferably methyl or ethyl; n represents the number of -CH2-, and n is any integer from 1 to 10; X1-X2 are each independently selected from OH, Br, Cl or I; The mineralizer is selected from one or more of sodium fluoride, sodium chloride, sodium bromide and ammonium fluoride.

9. The method according to claim 6, characterized in that In step (2), the weight ratio of the gel molecular sieve to the first ammonium salt solution is 1: (10-30); the temperature of the first drying is 80-150° C., preferably 100-120° C.; the time is 8-12 hours, preferably 8-10 hours; the temperature of the first calcination is 400-600° C., preferably 450-550° C.; the time is 2-6 hours, preferably 3-5 hours; The concentration of the first ammonium salt solution is 10-30% by weight, and the first ammonium salt solution is selected from one or more of ammonium chloride solution, ammonium nitrate solution and ammonium sulfate solution.

10. The method according to claim 6, characterized in that In step (3), the weight ratio of the solid molecular sieve to the second ammonium salt solution is 1: (20-30); the temperature of the ion exchange is 60-100° C., preferably 65-80° C.; the time is 2-8 hours, preferably 4-8 hours; the temperature of the second drying is 80-150° C., preferably 80-120° C.; the time is 8-12 hours, preferably 8-10 hours; the temperature of the second calcination is 400-600° C., preferably 450-550° C.; the time is 2-6 hours, preferably 3-5 hours; The concentration of the second ammonium salt solution is 10-30% by weight, and the second ammonium salt solution is selected from one or more of ammonium chloride solution, ammonium nitrate solution and ammonium sulfate solution.

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