Process for the preparation of a catalyst for the alkylation of naphthalene based on a hierarchical porous molecular sieve and use thereof

Abstract

This invention relates to the field of catalysis, and discloses a method for preparing a naphthalene alkylation catalyst based on a hierarchical porous molecular sieve and its application. The preparation method includes: 1) treating a low silica-to-alumina ratio zeolite molecular sieve with a microporous structure by steam treatment or acid washing to obtain a dealuminized molecular sieve; 2) treating the dealuminized molecular sieve with a mixed aqueous solution of tetraethylammonium hydroxide and alkali to obtain a surface-rich silica-based hierarchical porous molecular sieve; 3) modifying the surface-rich silica-based hierarchical porous molecular sieve with ammonium ion exchange and calcining to obtain an alkylation catalyst, wherein the inner layer has a hierarchical porous structure with micropores and mesopores, and the outer layer is mainly mesoporous inert silica. The naphthalene alkylation catalyst prepared by this invention has a hierarchical porous structure with micropores and mesopores in the inner layer and an outer layer mainly mesoporous inert silica. This catalyst has the advantages of high selectivity, good mass transfer efficiency, and low deactivation.

Description

Technical Field

[0001] This invention relates to the field of catalysis, and more particularly to a method for preparing a naphthalene alkylation catalyst based on a hierarchical porous molecular sieve and its application. Background Technology

[0002] Polyethylene naphthalene glycol (PEN) is a novel high-performance polymer exhibiting excellent heat resistance, mechanical properties, gas barrier properties, chemical stability, and radiation resistance. It can be widely used in electronic components, instruments, and insulating materials, and can promote the development of industries such as electric vehicles and aerospace. 2,6-Diisopropylnaphthalene is one of the precursors of 2,6-naphthalenedicarboxylic acid, the monomer for the preparation of PEN. However, its preparation process is complex and costly, which limits the large-scale application of PEN.

[0003] The synthesis of 2,6-diisopropylnaphthalene via alkylation with propylene using inexpensive and abundant naphthalene as a raw material is an ideal process route. However, 2,6-diisopropylnaphthalene has as many as 10 isomers with similar boiling points, making separation difficult. Therefore, improving the selectivity of 2,6-diisopropylnaphthalene is crucial for its preparation from naphthalene. Furthermore, molecular sieve catalysts used in the alkylation of naphthalene and propylene often suffer from coking and deactivation, exhibiting poor catalyst stability and requiring frequent regeneration. This undoubtedly reduces production efficiency and increases production costs. Therefore, developing a highly stable catalyst for the alkylation of naphthalene and propylene is particularly important.

[0004] Patent CN1793088A discloses a method for preparing 2,6-diisopropylnaphthalene by hydroisopropylation of refined naphthalene, achieving an average conversion rate of >90% over multiple consecutive batches under hydroisopropylation conditions, with an average 2,6-diisopropylnaphthalene content of >35% in the product. Patent CN107954812A discloses a method for preparing 2,6-diisopropylnaphthalene by alkylation of naphthalene with propylene using silanized modified ZSM-5 / ZSM-12 composite molecular sieves, achieving a naphthalene conversion rate of 31% and a 2,6-diisopropylnaphthalene selectivity of 41%. The above reports suffer from the problem of not being able to simultaneously achieve both activity and selectivity, or both being relatively low.

[0005] Furthermore, patent CN117983289A provides a method for preparing HMOR@AlPO4-11 core-shell molecular sieves for the preparation of 2,6-diisopropylnaphthalene. This method improves the yield and purity of 2,6-diisopropylnaphthalene by generating a weakly acidic AlPO4-11 molecular sieve layer on the outer surface of the HMOR molecular sieve. The disadvantage of this method is that the core portion of the HMOR@AlPO4-11 core-shell molecular sieve is a microporous molecular sieve (MOR), and the presence of only micropores is not conducive to mass transfer, easily leading to low catalyst activity and rapid deactivation. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that in the prior art, the catalyst is prone to deactivation and has low shape selectivity during the naphthalene alkylation reaction. A preparation method of a naphthalene alkylation catalyst based on a hierarchical zeolite molecular sieve is provided. The inner layer of the naphthalene alkylation catalyst prepared by the present invention has a hierarchical pore structure of micropores and mesopores, and the outer layer is inert silica mainly composed of mesopores. The catalyst has the advantages of high selectivity, good mass transfer efficiency and being not easily deactivated.

[0007] The specific technical solution of the present invention includes: In the first aspect, the present invention provides a preparation method of a naphthalene alkylation catalyst based on a hierarchical zeolite molecular sieve, which includes the following steps: 1) A low-silica-alumina ratio (molar ratio of 5 < Si / Al < 15) zeolite molecular sieve with a microporous structure is treated by steam or pickling to obtain a dealuminated molecular sieve.

[0008] In step 1), after being treated by steam or pickling, the low-Si / Al ratio zeolite molecular sieve can achieve preliminary dealumination treatment, so that it is easier to be eroded by alkali in the subsequent process (there is a counterbalancing cation such as Na

[0009] , , - , ,

[0010] ) around the tetrahedral framework aluminum (Al + 、H + , which can combine with alkali (OH - ) and has a protective effect on the silicon adjacent to the framework aluminum. The lower the Si / Al ratio, the higher the content of framework aluminum, and the less likely the silicon in the molecular sieve is to be eroded by alkali. Therefore, the present invention first removes part of the framework aluminum to make the silicon more easily eroded by alkali), generating mesopores and creating conditions for the final formation of a hierarchical pore structure.

[0009] 2) The dealuminated molecular sieve is treated with a mixed aqueous solution of tetraethylammonium hydroxide (TEAOH) and alkali to obtain a silicon-rich hierarchical pore molecular sieve on the surface.

[0010] In step 2), the dealuminolite molecular sieve can form a mesoporous structure after being corroded by alkali, thus forming a multi-level pore structure with the original micropores of the molecular sieve. During this process, TEAOH is adsorbed onto the surface of the molecular sieve. Its functions are twofold: firstly, it can limit the degree of alkali erosion, avoiding excessive erosion that leads to a low solid yield, and making the mesopore size distribution more uniform; secondly, the silicon species removed by alkali erosion of the molecular sieve can recrystallize on the outer surface of the molecular sieve under the action of TEAOH, forming a multi-level porous molecular sieve with a silicon-rich outer surface. This is beneficial to improving the catalyst conversion rate, 2,6-diisopropylnaphthalene selectivity, and anti-coking ability (the multi-level porous structure of the molecular sieve is conducive to the diffusion and transport of substances, and the reactants naphthalene and propylene can more easily diffuse to the active sites to react, thereby improving the conversion rate; the reaction products can also more easily diffuse out of the molecular sieve, avoiding the formation of coking precursors from deep reactions, thus improving the catalyst's anti-coking ability; the silicon-rich shell on the outer surface of the molecular sieve has extremely low or even inert reactivity, which can reduce the conversion of the target product 2,6-diisopropylnaphthalene into other isomers, such as 2,7-diisopropylnaphthalene).

[0011] Furthermore, this invention has found that TEAOH is more effective than other types of surfactants, such as tetrapropylammonium hydroxide (TPAOH) and hexadecyltrimethylammonium bromide (CTAB).

[0012] 3) The surface-rich silica hierarchical porous molecular sieve was modified by ammonium ion exchange and calcined to obtain an alkylation catalyst.

[0013] In step 3), after treating the molecular sieve with an alkaline solution such as sodium hydroxide solution, the cations used to balance the negative charge of Al in the framework are mostly Na. + It does not have catalytic activity for alkylation reactions and requires the replacement of Na with ammonium ions. + Then, after high-temperature calcination, it is converted into H, which has catalytic activity. + .

[0014] In summary, the catalyst prepared by the method of this invention has a hierarchical porous structure with micropores and mesopores in its inner layer (made of aluminosilicate molecular sieve), and an outer layer of mainly mesoporous inert silica. When this catalyst is applied to the alkylation reaction of naphthalene to prepare 2,6-diisopropylnaphthalene, it not only exhibits high conversion and selectivity, but also higher mass transfer efficiency and stronger resistance to carbon deposition.

[0015] Preferably, in step 2), the concentration of the tetraethylammonium hydroxide is 0.05-0.2 mol / L, more preferably 0.1 mol / L; and the concentration of the alkali is 0.1-0.4 mol / L, more preferably 0.2 mol / L.

[0016] This invention reveals that the concentrations of tetraethylammonium hydroxide (TEAOH) and the alkali in step 2) significantly impact the performance of the final catalyst. TEAOH adsorbs onto the molecular sieve surface, limiting the extent of alkali erosion, preventing excessive erosion that leads to low solid yield, and promoting a more uniform mesopore size distribution. The molecular sieve surface needs to be covered with TEAOH to control the degree of alkali erosion, while also exposing some surface area to allow for mesopore formation under the influence of the alkali. Therefore, the TEAOH concentration should be controlled within the aforementioned reasonable range. Similarly, too low an alkali concentration is insufficient to effectively generate mesopores, while too high a concentration still carries the risk of excessive erosion.

[0017] Preferably, in step 1), the zeolite molecular sieve is selected from zeolite molecular sieves with topological structures such as BEA, FAU, and MOR.

[0018] Preferably, in step 1), the temperature of the steam treatment is 300-600 ℃, more preferably 500 ℃; and the treatment time is 3-10 h, more preferably 5 h.

[0019] Molecular sieves undergo skeletal aluminum removal under the action of high-temperature steam. If the temperature is too low, skeletal aluminum is difficult to remove effectively; if the temperature is too high, excessive removal of skeletal aluminum occurs, making it difficult to control the degree of erosion of the molecular sieve skeleton during subsequent alkaline treatment. Furthermore, if the Si / Al ratio of the molecular sieve skeleton is too high, the number of acidic active centers is low, which is not conducive to the occurrence of catalytic reactions. Therefore, the temperature of high-temperature steam treatment should be within the above range.

[0020] Preferably, in step 1), the acid used for pickling is selected from hydrochloric acid, oxalic acid, and citric acid, and more preferably citric acid.

[0021] Preferably, in step 1), the acid concentration of the pickling treatment is 0.5-2 mol / L, more preferably 1 mol / L; the solid-liquid ratio is 1 g: 15-25 mL; the temperature is 80-120 ℃, more preferably 100 ℃; and the treatment time is 1-10 h, more preferably 5 h.

[0022] Preferably, in step 2), the alkali is selected from sodium hydroxide, sodium carbonate, and ammonia, and more preferably sodium hydroxide.

[0023] Preferably, in step 2), the solid-liquid ratio of the dealuminized molecular sieve and the mixed aqueous solution is 1 g: 15-25 mL.

[0024] Preferably, in step 2), the temperature of the treatment is 60-100 ℃, more preferably 80 ℃; and the treatment time is 1-5 h, more preferably 2 h.

[0025] Preferably, in step 3), the ammonium ion exchange modification is performed by immersing a surface-rich silica hierarchical porous molecular sieve into a solution containing ammonium ions for ammonium ion exchange modification.

[0026] More preferably, in step 3), the ammonium ion solution is an aqueous solution of ammonium nitrate or ammonium chloride with a concentration of 0.5-1.5 mol / L, and more preferably an aqueous solution of ammonium nitrate.

[0027] More preferably, in step 3), the solid-liquid ratio of the surface-rich silica hierarchical porous molecular sieve to the ammonium ion-containing solution is 5-10 g / 100mL.

[0028] More preferably, in step 3), the ammonium ion exchange modification is performed at a temperature of 70-90 °C, 1-5 times, and for 2-6 hours each time.

[0029] Secondly, the present invention provides an application of the alkylation catalyst prepared by the above preparation method in the preparation of 2,6-diisopropylnaphthalene by naphthalene alkylation reaction.

[0030] Preferably, the application includes: placing an alkylation catalyst and naphthalene in a reactor, introducing propylene under inert conditions, and carrying out a naphthalene alkylation reaction to obtain 2,6-diisopropylnaphthalene.

[0031] More preferably, the reaction conditions for the naphthalene alkylation are as follows: the mass of the alkylation catalyst is 5-10% of naphthalene; the molar ratio of propylene to naphthalene is 1.5-2.5:1; the reaction pressure is 0.5-2.5 MPa; and the reaction temperature is 200-300 °C.

[0032] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention utilizes alkali corrosion to dealuminate molecular sieves to form a mesoporous structure, thereby forming a hierarchical pore structure with the original micropores of the molecular sieve. On this basis, this invention limits the degree of alkali corrosion by TEAOH to avoid excessive corrosion leading to a low solid yield and to make the mesopore size distribution more uniform; at the same time, the silicon species removed by alkali corrosion of the molecular sieve can recrystallize on the outer surface of the molecular sieve under the action of TEAOH, forming a hierarchical pore molecular sieve with silicon-rich outer surface, which is beneficial to improving the catalyst conversion rate, 2,6-diisopropylnaphthalene selectivity and anti-carbon deposition ability.

[0033] (2) The catalyst prepared by the method of the present invention has a hierarchical pore structure with micropores and mesopores in the inner layer (the material is aluminosilicate molecular sieve), and the outer layer is mainly mesoporous inert silica. When this catalyst is applied to the alkylation reaction of naphthalene to prepare 2,6-diisopropylnaphthalene, it not only has a high conversion rate and selectivity, but also a higher mass transfer efficiency, strong resistance to carbon deposition, and is not easily deactivated. Detailed Implementation

[0034] The present invention will be further described below in conjunction with embodiments.

[0035] General Embodiment In a first aspect, a method for preparing a naphthalene alkylation catalyst based on a hierarchical pore molecular sieve includes the following steps: 1) A low-silica-alumina ratio (5 < Si / Al < 15) zeolite molecular sieve with a microporous structure is treated by steam treatment or pickling treatment to obtain a dealuminated molecular sieve.

[0036] In some preferred embodiments, in step 1), the zeolite molecular sieve is selected from zeolite molecular sieves having topological structures such as BEA, FAU, and MOR.

[0037] In some preferred embodiments, in step 1), the temperature of the steam treatment is 300 - 600 °C, further preferably 500 °C; the treatment time is 3 - 10 h, further preferably 5 h.

[0038] In some preferred embodiments, in step 1), the acid for pickling treatment is selected from hydrochloric acid, oxalic acid, and citric acid, further preferably citric acid.

[0039] In some preferred embodiments, in step 1), the acid concentration for pickling treatment is 0.5 - 2 mol / L, further preferably 1 mol / L; the solid-liquid ratio is 1 g : 15 - 25 mL; the temperature is 80 - 120 °C, further preferably 100 °C; the treatment time is 1 - 10 h, further preferably 5 h.

[0040] 2) The dealuminated molecular sieve is treated with an aqueous mixed solution of tetraethylammonium hydroxide (TEAOH) and a base to obtain a hierarchical pore molecular sieve rich in silicon on the surface.

[0041] In some preferred embodiments, in step 2), the base is selected from sodium hydroxide, sodium carbonate, and ammonia water, further preferably sodium hydroxide.

[0042] In some preferred embodiments, in step 2), the concentration of tetraethylammonium hydroxide (TEAOH) is 0.05 - 0.2 mol / L, further preferably 0.1 mol / L; the concentration of the base is 0.1 - 0.4 mol / L, further preferably 0.2 mol / L.

[0043] In some preferred embodiments, in step 2), the solid-liquid ratio of the dealuminated molecular sieve to the aqueous mixed solution is 1 g : 15 - 25 mL.

[0044] In some preferred embodiments, in step 2), the processing temperature is 60-100 ℃, more preferably 80 ℃; the processing time is 1-5 h, more preferably 2 h.

[0045] 3) The surface-rich silica hierarchical porous molecular sieve is modified by ammonium ion exchange and calcined to obtain an alkylation catalyst. Its inner layer has a hierarchical porous structure with micropores and mesopores (the material is aluminosilicate molecular sieve), and the outer layer is mainly mesoporous inert silica.

[0046] In some preferred embodiments, in step 3), the ammonium ion exchange modification is performed by immersing a surface-rich silica hierarchical porous molecular sieve into a solution containing ammonium ions for ammonium ion exchange modification.

[0047] In some preferred embodiments, in step 3), the ammonium ion solution is an aqueous solution of ammonium nitrate or ammonium chloride with a concentration of 0.5-1.5 mol / L, more preferably an aqueous solution of ammonium nitrate.

[0048] In some preferred embodiments, in step 3), the solid-liquid ratio of the surface-rich silica hierarchical porous molecular sieve to the ammonium ion-containing solution is 5-10 g / 100mL.

[0049] In some preferred embodiments, in step 3), the ammonium ion exchange modification is performed at a temperature of 70-90°C, 1-5 times, and for 2-6 hours each time.

[0050] Secondly, the application of an alkylation catalyst prepared by the above method in the preparation of 2,6-diisopropylnaphthalene by naphthalene alkylation reaction.

[0051] In some preferred embodiments, the application includes: placing an alkylation catalyst and naphthalene in a reactor, introducing propylene under inert conditions, and carrying out a naphthalene alkylation reaction to obtain 2,6-diisopropylnaphthalene.

[0052] In some more preferred embodiments, the reaction conditions for naphthalene alkylation are as follows: the mass of the alkylation catalyst is 5-10% of naphthalene; the molar ratio of propylene to naphthalene is 1.5-2.5:1; the reaction pressure is 0.5-2.5 MPa; and the reaction temperature is 200-300°C.

[0053] Specific embodiments and comparative examples The conversion rate and selectivity are calculated as follows in the following cases: Naphthalene conversion rate = number of moles of naphthalene converted / initial number of moles of naphthalene × 100; 2,6-diisopropylnaphthalene selectivity = number of moles of 2,6-diisopropylnaphthalene / total number of moles of product × 100.

[0054] (1) Take 15 g of MOR molecular sieve (WAKO#329-27805) and place it in a tube furnace. Treat it at 500 °C for 5 h under a steam atmosphere.

[0055] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.2 mol / L NaOH and 0.1 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0056] (3) Take 12.1 g of the powder obtained in the previous step and exchange it with 240 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0057] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0058] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0059] (6) Analysis and testing of reaction results: naphthalene conversion rate was 97.2%, 2,6-diisopropylnaphthalene selectivity was 68.6%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 91.3% and the 2,6-diisopropylnaphthalene selectivity was 71.6%.

[0060] Comparative Example 1 The difference between this case and Example 1 is that the molecular sieve after dealumination is not treated with a mixed solution of NaOH and TEAOH. The specific steps are as follows: (1) Take 15 g of MOR molecular sieve (WAKO#329-27805) and place it in a tube furnace. Under a steam atmosphere, treat it at 500 °C for 5 h and dry it at 110 °C for 12 h to obtain a powdered catalyst.

[0061] (2) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0062] (3) Analysis and testing of reaction results: naphthalene conversion rate was 80.8%, 2,6-diisopropylnaphthalene selectivity was 42.7%, and after the catalyst was recycled 6 times, naphthalene conversion rate was 16.4% and 2,6-diisopropylnaphthalene selectivity was 47.3%.

[0063] Comparative Example 2 The difference between this case and Example 1 is that the steam treatment temperature is lower and the degree of dealuminization is lower. The specific steps are as follows: (1) Take 15 g of MOR molecular sieve (WAKO#329-27805) and place it in a tube furnace. Treat it at 100 °C for 5 h under a steam atmosphere.

[0064] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.2 mol / L NaOH and 0.1 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0065] (3) Take 14.2 g of the powder obtained in the previous step and exchange it with 280 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0066] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0067] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0068] (6) Analysis and testing of reaction results: Naphthalene conversion rate 47.2%, 2,6-diisopropylnaphthalene selectivity 45.3% (due to the low degree of dealumination of Comparative Example 2, it is not easy to generate mesopores during alkali treatment, and its acid site density is high, which makes it easy to generate coke during the reaction, resulting in a low conversion rate. Therefore, no cycle test was performed).

[0069] Comparative Example 3 The difference between this case and Example 1 is that TEAOH is not present in step (2). The specific steps are as follows: (1) Take 15 g of MOR molecular sieve (WAKO#329-27805) and place it in a tube furnace. Treat it at 500 °C for 5 h under a steam atmosphere.

[0070] (2) Place the dealuminolite obtained in the previous step into 300 mL of 0.2 mol / L NaOH solution, treat at 80 °C for 2 h, centrifuge, wash, and dry at 110 °C for 12 h.

[0071] (3) Take 8.5 g of the powder obtained in the previous step and exchange it three times at 80 °C with 170 mL of 1 mol / L NH4NO3 solution (because there is no TEAOH to protect the molecular sieve in Comparative Example 3, only NaOH erosion is performed, resulting in a low powder solid yield). Each time, the exchange lasts for 4 hours.

[0072] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0073] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0074] (6) Analysis and testing of reaction results: naphthalene conversion rate was 94.5%, 2,6-diisopropylnaphthalene selectivity was 38.7%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 31.4% and the 2,6-diisopropylnaphthalene selectivity was 52.9%.

[0075] (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in a tube furnace. Treat it at 500 °C for 4 h under a steam atmosphere.

[0076] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.2 mol / L NaOH and 0.1 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0077] (3) Take 13.3 g of the powder obtained in the previous step and exchange it with 260 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0078] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0079] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0080] (6) Analysis and testing of reaction results: naphthalene conversion rate was 96.5%, 2,6-diisopropylnaphthalene selectivity was 58.3%, and after the catalyst was recycled 6 times, naphthalene conversion rate was 91.8% and 2,6-diisopropylnaphthalene selectivity was 61.6%.

[0081] (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in a tube furnace. Treat it at 500 °C for 5 h under a steam atmosphere.

[0082] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.4 mol / L NaOH and 0.1 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0083] (3) Take 10.2 g of the powder obtained in the previous step and exchange it with 200 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0084] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0085] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0086] (6) Analysis and testing of reaction results: naphthalene conversion rate was 95.3%, 2,6-diisopropylnaphthalene selectivity was 57.3%, and after the catalyst was recycled 6 times, naphthalene conversion rate was 92.4% and 2,6-diisopropylnaphthalene selectivity was 61.2%.

[0087] (1) Take 15 g of BEA molecular sieve (Adamas#4151892FB) and place it in a tube furnace. Treat it at 400 °C for 4 h under a steam atmosphere.

[0088] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.4 mol / L NaOH and 0.2 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0089] (3) Take 10.9 g of the powder obtained in the previous step and exchange it with 220 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0090] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0091] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0092] (6) Analysis and testing of reaction results: naphthalene conversion rate was 92.3%, 2,6-diisopropylnaphthalene selectivity was 52.4%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 88.7% and the 2,6-diisopropylnaphthalene selectivity was 56.1%.

[0093] (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in 300 mL of 1 mol / L citric acid solution. Treat it at 100 °C for 5 h, filter, wash, dry at 110 °C for 12 h, and calcine at 540 °C for 4 h.

[0094] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.2 mol / L NaOH and 0.1 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0095] (3) Take 12.9 g of the powder obtained in the previous step and exchange it with 260 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0096] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0097] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0098] (6) Analysis and testing of reaction results: naphthalene conversion rate was 96.8%, 2,6-diisopropylnaphthalene selectivity was 64.7%, and after the catalyst was recycled 6 times, naphthalene conversion rate was 91.6% and 2,6-diisopropylnaphthalene selectivity was 68.5%.

[0099] Comparative Example 4 The difference between this case and Example 5 is that there is no NaOH in step (2). The specific steps are as follows: (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in 300 mL of 1 mol / L citric acid solution. Treat it at 100 °C for 5 h, filter, wash, dry at 110 °C for 12 h, and calcine at 540 °C for 4 h.

[0100] (2) The dealuminolite obtained in the previous step was placed in 300 mL of 0.1 mol / L TEAOH solution, treated at 80 °C for 2 h, centrifuged, washed, dried at 110 °C for 12 h, and calcined at 540 °C for 4 h.

[0101] (3) Take 13.9 g of the powder obtained in the previous step and exchange it with 280 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0102] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0103] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0104] (6) Analysis and testing of reaction results: naphthalene conversion rate was 87.2%, 2,6-diisopropylnaphthalene selectivity was 58.6%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 15.3% and the 2,6-diisopropylnaphthalene selectivity was 62.4%.

[0105] Comparative Example 5 The difference between this case and Example 5 is that in step (2), hexadecyltrimethylammonium bromide (CTAB) is used instead of TEAOH. The specific steps are as follows: (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in 300 mL of 1 mol / L citric acid solution. Treat it at 100 °C for 5 h, filter, wash, dry at 110 °C for 12 h, and calcine at 540 °C for 4 h.

[0106] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.2 mol / L NaOH and 0.1 mol / L CTAB, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0107] (3) Take 12.4 g of the powder obtained in the previous step and exchange it with 250 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0108] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0109] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0110] (6) Analysis and testing of reaction results: naphthalene conversion rate was 92.5%, 2,6-diisopropylnaphthalene selectivity was 53.3%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 56.5% and the 2,6-diisopropylnaphthalene selectivity was 59.6%.

[0111] Comparative Example 6 The difference between this case and Example 5 is that tetrapropylammonium hydroxide (TPAOH) is used instead of TEAOH in step (2). The specific steps are as follows: (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in 300 mL of 1 mol / L citric acid solution. Treat it at 100 °C for 5 h, filter, wash, dry at 110 °C for 12 h, and calcine at 540 °C for 4 h.

[0112] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.2 mol / L NaOH and 0.1 mol / L TPAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0113] (3) Take 12.0 g of the powder obtained in the previous step and exchange it with 240 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0114] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0115] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0116] (6) Analysis and testing of reaction results: naphthalene conversion rate was 93.2%, 2,6-diisopropylnaphthalene selectivity was 54.6%, and after the catalyst was recycled 6 times, naphthalene conversion rate was 48.5% and 2,6-diisopropylnaphthalene selectivity was 61.8%.

[0117] Comparative Example 7 The difference between this case and Example 5 is that the concentration of TEAOH in step (2) is too low. The specific steps are as follows: (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in 300 mL of 1 mol / L citric acid solution. Treat it at 100 °C for 5 h, filter, wash, dry at 110 °C for 12 h, and calcine at 540 °C for 4 h.

[0118] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.2 mol / L NaOH and 0.02 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0119] (3) Take 12.0 g of the powder obtained in the previous step and exchange it with 240 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0120] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0121] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0122] (6) Analysis and testing of reaction results: naphthalene conversion rate was 90.3%, 2,6-diisopropylnaphthalene selectivity was 49.6%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 39.4% and the 2,6-diisopropylnaphthalene selectivity was 57.8%.

[0123] Comparative Example 8 The difference between this case and Example 5 is that the concentration of TEAOH is too high in step (2). The specific steps are as follows: (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in 300 mL of 1 mol / L citric acid solution. Treat it at 100 °C for 5 h, filter, wash, dry at 110 °C for 12 h, and calcine at 540 °C for 4 h.

[0124] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.2 mol / L NaOH and 0.4 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0125] (3) Take 13.1 g of the powder obtained in the previous step and exchange it with 260 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0126] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0127] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0128] (6) Analysis and testing of reaction results: naphthalene conversion rate was 92.5%, 2,6-diisopropylnaphthalene selectivity was 44.8%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 21.5% and the 2,6-diisopropylnaphthalene selectivity was 62.7%.

[0129] Comparative Example 9 The difference between this case and Example 5 is that the concentration of NaOH in step (2) is too low. The specific steps are as follows: (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in 300 mL of 1 mol / L citric acid solution. Treat it at 100 °C for 5 h, filter, wash, dry at 110 °C for 12 h, and calcine at 540 °C for 4 h.

[0130] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.02 mol / L NaOH and 0.1 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0131] (3) Take 12.9 g of the powder obtained in the previous step and exchange it with 260 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0132] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0133] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0134] (6) Analysis and testing of reaction results: naphthalene conversion rate was 89.1%, 2,6-diisopropylnaphthalene selectivity was 57.5%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 27.6% and the 2,6-diisopropylnaphthalene selectivity was 60.4%.

[0135] Comparative Example 10 The difference between this case and Example 5 is that the concentration of NaOH in step (2) is too high. The specific steps are as follows: (1) Take 15 g of FAU molecular sieve (Adamas#4155850KC) and place it in 300 mL of 1 mol / L citric acid solution. Treat it at 100 °C for 5 h, filter, wash, dry at 110 °C for 12 h, and calcine at 540 °C for 4 h.

[0136] (2) The dealuminolite obtained in the previous step was placed in a 300 mL mixed solution of 0.8 mol / L NaOH and 0.1 mol / L TEAOH, treated at 80 °C for 2 h, centrifuged, washed, and dried at 110 °C for 12 h.

[0137] (3) Take 12.9 g of the powder obtained in the previous step and exchange it with 260 mL of 1 mol / L NH4NO3 solution at 80 °C 3 times, each time for 4 h.

[0138] (4) The solid obtained in the previous step is dried and calcined at 540 °C for 4 h to obtain a powdered catalyst.

[0139] (5) Evaluation of the alkylation reaction of naphthalene and propylene was carried out in a 100 mL reactor. 2.4 g of naphthalene and 0.24 g of catalyst were placed in the reactor, sealed, and the air in the reactor was replaced with nitrogen. The nitrogen in the reactor was replaced with propylene. The molar ratio of propylene to naphthalene was 2:1, and the reaction temperature was 280 °C.

[0140] (6) Analysis and testing of reaction results: naphthalene conversion rate was 94.0%, 2,6-diisopropylnaphthalene selectivity was 48.9%, and after the catalyst was recycled 6 times, the naphthalene conversion rate was 42.4% and the 2,6-diisopropylnaphthalene selectivity was 57.1%.

[0141] Performance Comparison The data for each embodiment and comparative example are shown in the table below: The data comparison in the table above shows that: Compared with Example 1, the molecular sieve after dealumination was not treated with a mixed solution of NaOH and TEAOH. The microporous structure of the molecular sieve hindered the diffusion of reactants and products, resulting in a lower conversion rate. In addition, there were many acidic sites on the outer surface of the molecular sieve, which aggravated the formation of coke during the reaction process. After multiple cycles, the conversion rate decreased significantly.

[0142] Compared to Example 1, the steam treatment temperature in Comparative Example 2 was lower, resulting in limited dealuminization of the molecular sieve. This was not conducive to subsequent alkaline treatment for desiliconization and mesoporous formation. Furthermore, due to the excessively high aluminum content in the molecular sieve framework and the high density of acid active sites, carbon deposits were easily formed during the reaction, leading to catalyst deactivation. The conversion rate was also low during the first use, so no cyclic experiment was conducted. In Comparative Example 3, no TEAOH was used during the alkaline treatment. Without the protection of TEAOH, the molecular sieve was excessively eroded by the alkali, resulting in the formation of large mesopores (and macropores) inside the molecular sieve. This had a certain promoting effect on the diffusion of reactants and products. However, because no TEAOH was used, the silicon species generated by the alkali erosion failed to recrystallize on the surface of the molecular sieve, and the surface acidity remained relatively high. The catalyst had a high conversion rate during the first use, but its activity decreased rapidly after repeated use.

[0143] Compared with Example 5, Comparative Example 4 did not use NaOH in the treatment process, and mesopores were not effectively formed in the molecular sieve, resulting in a lower conversion rate. In addition, there were no silicon-rich species generated by alkali erosion, and the outer surface of the molecular sieve was more acidic. After multiple cycles, the catalyst activity was low.

[0144] Compared with Example 5, Comparative Examples 5 and 6 used CTAB and TPAOH instead of TEAOH to treat the molecular sieve with alkali, respectively. Some mesopores were generated in the molecular sieve, but CTAB and TPAOH failed to effectively guide the species generated by alkali erosion to recrystallize on the surface of the molecular sieve. There were still a considerable number of acidic sites on the outer surface of the molecular sieve. After multiple cycles, the conversion rate decreased.

[0145] Compared with Example 5, the TEAOH concentration in Comparative Example 7 was too low, which could not effectively resist the erosion of the alkali. Moreover, the generated silicon-rich species lacked the guidance of the template agent and failed to recrystallize on the surface of the molecular sieve. The outer surface of the molecular sieve was more acidic, and the catalyst activity was low after multiple cycles. In Comparative Example 8, the TEAOH concentration was too high. The alkali erosion caused mesopore blockage and did not produce a sufficient amount of silicon-rich species. The surface acidity was still relatively high. The catalyst had a high conversion rate when used for the first time, but its activity decreased rapidly after multiple uses.

[0146] Compared with Example 5, the NaOH concentration in Comparative Example 9 was too low, failing to effectively erode the molecular sieve and generate a sufficient amount of silicon-rich species. The outer surface of the molecular sieve was more acidic, and the catalyst activity was low after multiple cycles. In Comparative Example 10, the NaOH concentration was too high, resulting in a strong alkaline erosion effect. The generated silicon-rich species were easily dissolved in a strongly alkaline environment and difficult to recrystallize on the surface of the molecular sieve. The surface acidity was still relatively high. The catalyst had a high conversion rate when used for the first time, but its activity decreased rapidly after multiple uses.

[0147] The above embodiments and comparative examples illustrate that only by combining the secondary hydrothermal crystallization treatment of dealubilized molecular sieve with liquid-phase silicon deposition modification can the conversion rate of the catalyst be improved, the resistance to carbon deposition be enhanced, and the stability be improved. At the same time, the hydrothermal stability of the catalyst is also improved, and it still has good performance after the catalyst is deactivated and regenerated.

[0148] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a naphthalene alkylation catalyst based on a hierarchical porous molecular sieve, characterized in that... include: 1) Low-silicon-alumina ratio zeolite molecular sieves with microporous structure and silicon-alumina molar ratio of 5-15:1 are treated with steam or acid to obtain dealuminized molecular sieves. 2) The dealuminolized molecular sieve was treated with a mixed aqueous solution containing 0.05-0.2 mol / L tetraethylammonium hydroxide and 0.1-0.4 mol / L alkali to obtain a silica-rich hierarchical porous molecular sieve. 3) The surface-rich silica hierarchical porous molecular sieve is modified by ammonium ion exchange and calcined to obtain an alkylation catalyst. Its inner layer has a hierarchical porous structure of micropores and mesopores, and the outer layer is mainly mesopore-based inert silica.

2. The preparation method according to claim 1, characterized in that: In step 1), the zeolite molecules are screened from zeolite molecular sieves with a topological structure.

3. The preparation method according to claim 1 or 2, characterized in that: In step 1), the temperature of the steam treatment is 300-600 ℃, and the treatment time is 3-10 h.

4. The preparation method according to claim 1 or 2, characterized in that: In step 1), The acid used in the pickling treatment is selected from hydrochloric acid, oxalic acid, and citric acid; The acid concentration for the pickling treatment is 0.5-2 mol / L, the solid-liquid ratio is 1 g: 15-25 mL, the temperature is 80-120 ℃, and the treatment time is 1-10 h.

5. The preparation method according to claim 1, characterized in that: In step 2), the alkali is selected from sodium hydroxide, sodium carbonate and ammonia.

6. The preparation method according to claim 1 or 5, characterized in that: In step 2), The solid-liquid ratio of the dealuminized molecular sieve and the mixed aqueous solution is 1g:15-25mL; The processing temperature is 60-100 ℃, and the processing time is 1-5 h.

7. The preparation method according to claim 1, characterized in that: In step 3), The ammonium ion exchange modification involves immersing a silica-rich hierarchical porous molecular sieve into a solution containing ammonium ions for ammonium ion exchange modification. The ammonium ion solution is an aqueous solution of ammonium nitrate or ammonium chloride with a concentration of 0.5-1.5 mol / L; The solid-liquid ratio of the surface-rich silica hierarchical porous molecular sieve to the ammonium ion-containing solution is 5-10 g / 100 mL; The ammonium ion exchange modification is performed at a temperature of 70-90 °C, 1-5 times, and for 2-6 hours each time.

8. The use of the alkylation catalyst prepared by the method according to any one of claims 1-7 in the preparation of 2,6-diisopropylnaphthalene by naphthalene alkylation reaction.

9. The application according to claim 8, characterized in that... include: An alkylation catalyst and naphthalene were placed in a reactor, and propylene was introduced under inert conditions to carry out a naphthalene alkylation reaction, yielding 2,6-diisopropylnaphthalene.

10. The application according to claim 9, characterized in that: The reaction conditions for the naphthalene alkylation are as follows: The alkylation catalyst comprises 5-10% naphthalene by mass; The molar ratio of propylene to naphthalene is 1.5-2.5:1; The reaction is carried out at a pressure of 0.5-2.5 MPa and a temperature of 200-300 ℃.

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