A process for the preparation of adamantane

Abstract

The application provides a method for preparing adamantane, which comprises: isomerizing tetrahydrodicyclopentadiene in the presence of a mesoporous mordenite molecular sieve catalyst with acid sites established by an organic acid, in the presence of an optional organic solvent, and in a hydrogen-containing atmosphere; and calculating the NH3-TPD peak area of the catalyst by integration, wherein the peak area of the weak acid center of the catalyst is greater than or equal to 330, the peak area of the strong acid center of the catalyst is less than or equal to 282, and the specific surface area of the catalyst is greater than or equal to 300 m 2 / g. In the synthesis of adamantane by the method, the isomerization reaction of adamantane is carried out in the presence of the above catalyst, at a reaction temperature of 250 DEG C, a hydrogen pressure of 1 Mpa, and in a 100-ml stainless steel autoclave. The product composition is analyzed by gas chromatography, and the chromatographic column is an HP-5 capillary column with a column length of 30 m. The purity of adamantane can reach more than 99%.

Description

Technical Field

[0001] This invention relates to a chemical synthesis method, and more particularly to a method for preparing adamantane by isomerization of tetrahydrodicyclopentadiene. Background Technology

[0002] Adamantane is a highly symmetrical cage-like alkane that has had wide applications in pharmaceuticals, fine chemicals, functional materials, military, and aerospace since its discovery and isolation from petroleum in the 1930s. Industrially, adamantane production commonly employs the tetrahydrodicyclopentadiene catalytic isomerization method using aluminum trichloride as the catalyst. However, the aluminum trichloride isomerization method has significant drawbacks. Specifically, it requires large quantities of aluminum trichloride, and during the reaction, aluminum trichloride forms complexes with heavy components, making recycling impossible and generating substantial amounts of aluminum waste that must be treated, as its emissions pollute the environment. Therefore, finding simple production processes and environmentally friendly solid acid catalysts has become an important research topic in this field both domestically and internationally.

[0003] Solid acids, such as zeolite molecular sieves, are widely used in the research of this reaction. Idemitsu Petrochemical Co., Ltd. of Japan reported in USP3944626 the industrial-scale synthesis of adamantane using bifunctional zeolite molecular sieves. This catalyst is a rare-earth ion-exchange zeolite molecular sieve supported with different metals, such as platinum, rhenium, nickel, and cobalt. The zeolite molecular sieves are mainly of type A, L, X, Y, and ZSM-5. Among them, the Pt-Re-Co / REY catalyst showed better performance, achieving adamantane yield of up to 31%. However, this type of catalyst uses precious metals as the main catalyst, resulting in high cost.

[0004] The diameter of an adamantane molecule is 0.74 nm. When synthesizing adamantane via molecular sieve-catalyzed isomerization, different requirements apply to the topological structure of the molecular sieve. In terms of topology, the main influence lies in the pore size of the molecular sieve. Molecular sieves with smaller pore sizes, such as ZSM-5, are completely ineffective at catalysis. This may be because larger kinetic diameter feed molecules cannot enter the smaller catalyst channels. Conversely, larger pore sizes, such as Y-type molecular sieves and mesoporous β-molecular sieves, exhibit varying catalytic effects due to their unique structures and properties. Therefore, selecting an appropriate type of molecular sieve is crucial when using molecular sieves to catalyze this isomerization reaction.

[0005] To produce adamantane using equipment prepared with inexpensive materials, Guo Jianwei et al. disclosed in CN1935756A a method of isomerizing adamantane by immersing mesoporous molecular sieves, such as Si-MCM-48, HMS, MSU, SBA-15, Al-MCM-41, Al-MCM-48, and Al-SBA-15, with inorganic acids. Specifically, under the conditions of using hydrochloric acid-treated Al-MCM-41 as a catalyst, a reaction temperature of 250℃, an H2 pressure of 1.0 MPa, and a reaction time of 3 h, the conversion rate of tetrahydrodicyclopentadiene was 82.5%, and the yield of adamantane was 20.3%.

[0006] CN1762927A discloses a solid acid ZrO. 2- SO4 2- Or surface loading of 10-20% ZrO2- / SO4 2- Microporous or mesoporous molecular sieves are used as catalysts in the synthesis of adamantane. This involves a 25% ZrO₂⁻ / SO₄ mixture. 2- On the MCM-41 catalyst, at a reaction temperature of 250℃ and an H2 pressure of 1.5MPa, the conversion rate of tetrahydrodicyclopentadiene was 90.70%, and the yield of adamantane was 27.06%. Summary of the Invention

[0007] The purpose of this invention is to address the problems existing in the prior art by providing a method for preparing adamantane that can significantly improve the yield of adamantane.

[0008] To achieve the aforementioned objective, the present invention provides a method for preparing adamantane, the method comprising: isomerizing tetrahydrodicyclopentadiene in the presence of a mesoporous mordenite molecular sieve catalyst with acidic sites established by an organic acid, in the presence of an optional organic solvent, under a hydrogen-containing atmosphere; determining the NH3-TPD peak area of ​​the catalyst by integration; wherein the weak acid center peak area of ​​the catalyst is above 330, the strong acid center peak area is below 282, and the specific surface area of ​​the catalyst is above 300 m². 2 / g or more.

[0009] In the method of this invention, the isomerization reaction of adamantane is carried out in the presence of the aforementioned catalyst in a stainless steel autoclave at a reaction temperature of 250°C, a hydrogen pressure of 1 MPa, and a solvent volume of 100 ml. The composition of the product is analyzed by gas chromatography using an HP-5 capillary column with a length of 30 m. The purity of the adamantane is above 99%, preferably above 99.2%, and more preferably above 99.5%. It is speculated that this is due to the establishment of acidic sites on the mesoporous mordenite molecular sieve by the organic acid, resulting in a decrease in the amount of strong acid and an increase in the specific surface area and the amount of weak acid. The decrease in the amount of strong acid effectively reduces the occurrence of side reactions, while the increase in specific surface area and the amount of weak acid favors the occurrence of the main reaction. This leads to an increased yield of adamantane. Attached Figure Description

[0010] Figure 1 The NH3-TPD curve of the mesoporous layered mordenite molecular sieve in Comparative Example 1 is shown.

[0011] Figure 2 The NH3-TPD curve of the mesoporous layered mordenite molecular sieve in Example 1 is shown.

[0012] Figure 3 The NH3-TPD curve of the mesoporous layered mordenite molecular sieve in Example 2 is shown.

[0013] Figure 4 The NH3-TPD curve of the mesoporous layered mordenite molecular sieve in Example 3 is shown.

[0014] Figure 5 This is a SEM image of the mesoporous layered mordenite molecular sieve from Example 2. Detailed Implementation

[0015] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0016] This invention provides a method for preparing adamantane, comprising: isomerizing tetrahydrodicyclopentadiene in the presence of a mesoporous mordenite molecular sieve catalyst with acidic sites established by an organic acid, in the presence of an optional organic solvent, and under a hydrogen-containing atmosphere; determining the NH3-TPD peak area of ​​the catalyst by integration; wherein the weak acid center peak area of ​​the catalyst is above 330, the strong acid center peak area is below 282, and the specific surface area of ​​the catalyst is above 300 m². 2 / g or more. The method for preparing adamantane of the present invention has a high yield of adamantane and a purity of 99% or more, preferably 99.2% or more, and more preferably 99.5% or more.

[0017] According to a preferred embodiment of the present invention, the silicon-to-aluminum ratio of the catalyst, expressed as a SiO2:Al2O3 molar ratio, is (10–30):1, preferably (16–20):1. The catalyst having the aforementioned characteristics can improve the yield of the target product.

[0018] According to a preferred embodiment of the present invention, the catalyst has a weak acid center peak area of ​​351–395 and a strong acid center peak area of ​​240–264. The catalyst having the aforementioned characteristics can improve the yield of the target product.

[0019] According to a preferred embodiment of the present invention, the catalyst has a layered microstructure, specifically as follows: Figure 5 As shown. Catalysts with the aforementioned characteristics can facilitate the diffusion of the target product, thereby increasing the yield of the target product.

[0020] According to a preferred embodiment of the present invention, the catalyst has a specific surface area of ​​300–600 m². 2 / g, preferably 400-500m 2 / g. Catalysts with the aforementioned characteristics can improve the yield of the target product.

[0021] According to the present invention, the mesoporous silicalite molecular sieve used can be a mesoporous layered silicalite molecular sieve or a mesoporous nano silicalite molecular sieve.

[0022] According to a preferred embodiment of the present invention, the preparation method of the catalyst includes: contacting an organic aqueous acid solution with a mesoporous mordenite molecular sieve, and drying and calcining the resulting solid.

[0023] According to a preferred embodiment of the present invention, the contact conditions include: intermittent stirring at a temperature of 20°C to 80°C, preferably 40°C to 60°C for 2 hours to 8 hours, with an interval of 10 minutes to 30 minutes after each stirring, followed by the next stirring, and preferably repeating the stirring-interval cycle 3 to 5 times, with each stirring session lasting 30 minutes to 60 minutes.

[0024] In this invention, there are no special requirements for the drying conditions, and conventional drying conditions can be used. According to a preferred embodiment of this invention, the drying conditions include: a drying temperature of 70℃~120℃ under an inert atmosphere, preferably 100℃~110℃, and the drying time is determined according to the drying temperature, generally 8h~16h, preferably 10h~12h.

[0025] In this invention, the inert atmosphere can be any inert atmosphere, such as a nitrogen atmosphere.

[0026] In this invention, there are no special requirements for the roasting conditions, and conventional roasting conditions can be used. According to a preferred embodiment of this invention, the roasting conditions include: a roasting temperature of 350℃~550℃ in an oxygen-containing atmosphere, preferably 500℃~550℃; and a roasting time determined according to the roasting temperature, preferably 2h~6h, preferably 4h~5h.

[0027] In this invention, the oxygen-containing atmosphere is an atmosphere containing oxygen, preferably with an oxygen concentration of 10% to 40% by volume, and for ease of operation, an air atmosphere is preferred.

[0028] In this invention, the concentration of the organic acid aqueous solution is preferably 0.1 mol / L to 3 mol / L, more preferably 0.5 mol / L to 1.5 mol / L. Using the aforementioned organic acid solution can further improve the catalytic activity of the catalyst.

[0029] According to a preferred embodiment of the present invention, the organic acid solution and the mesoporous mordenite molecular sieve are used in an equal volume impregnation ratio.

[0030] According to a preferred embodiment of the present invention, the organic acid is selected from one or more of mono- or poly-organic acids, hydroxy mono- or poly-organic acids, and preferably from one or more of citric acid, tartaric acid, acetic acid, oxalic acid, and glycolic acid. Using the aforementioned organic acids can further improve the catalytic activity of the catalyst.

[0031] According to a preferred embodiment of the present invention, the organic acid is a mixture of tartaric acid and citric acid, more preferably a mass ratio of tartaric acid to citric acid of 1:2 to 8, and more preferably 1:3 to 7. Using the aforementioned organic acid can further improve the catalytic activity of the catalyst.

[0032] According to a preferred embodiment of the present invention, the method comprises: isomerizing tetrahydrodicyclopentadiene dissolved in an organic solvent in the presence of a mesoporous mordenite molecular sieve catalyst in which an organic acid establishes acidic sites, under a hydrogen-containing atmosphere.

[0033] According to a preferred embodiment of the present invention, preferably, the organic solvent is selected from one or more of cyclohexane, methylcyclohexane, ethylcyclohexane, diethylcyclohexane, and methylethylcyclohexane.

[0034] In this invention, the isomerization conditions can be conventional, and there are no special requirements for them. For this invention, preferred isomerization reaction conditions include a reaction temperature of 180℃ to 300℃, preferably 200℃ to 300℃. Using the aforementioned temperature can improve the yield of the target product.

[0035] According to the present invention, preferred isomerization reaction conditions include a hydrogen pressure of 0.5 MPa to 2.5 MPa, preferably 0.5 MPa to 2 MPa. Using the aforementioned hydrogen pressure can improve the yield of the target product.

[0036] According to the present invention, the preferred isomerization reaction time is 1 h to 9 h, preferably 3 h to 7 h. Using the aforementioned reaction time can improve the yield of the target product.

[0037] In this invention, the mesoporous mordenite molecular sieve can be commercially available or synthesized in-house. For example, it can be synthesized using the following method: according to a molar ratio of SiO2 / Al2O3 = 10-50, OH... - / SiO2=0.2~0.4, Na / SiO2=0.3~0.5, TEABr / SiO2=0.03~0.10, CTAB / SiO2=0.01~0.05, H2O / SiO2=10~30, where TEABr represents tetraethylammonium bromide and CTAB represents hexadecyltrimethylammonium bromide. Weigh out sodium aluminate, sodium hydroxide, silica, tetraethylammonium bromide, hexadecyltrimethylammonium bromide, and deionized water.

[0038] Sodium hydroxide and sodium aluminate were dissolved separately in deionized water to prepare solutions. Silica, tetraethylammonium bromide, and hexadecyltrimethylammonium bromide were added sequentially to the prepared sodium aluminate aqueous solution. Sodium hydroxide solution was slowly added while stirring vigorously. The mixture was stirred at room temperature for 30–60 minutes. The mixture was then transferred to a hydrothermal crystallization vessel with a tetrafluoroethylene liner and reacted at 140–200°C for 24–72 hours. After crystallization, the vessel was removed, yielding a layered mordenite molecular sieve suspension. This suspension was dried at room temperature for 12–48 hours and then calcined in a muffle furnace at 500–600°C in air atmosphere to obtain a mesoporous layered mordenite molecular sieve.

[0039] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0040] Unless otherwise specified in the examples, the conditions were performed according to standard conditions or the manufacturer's recommendations. All reagents and instruments used, unless otherwise stated, were commercially available products.

[0041] In the following embodiments, the yield of adamantane is calculated according to the following formula (1):

[0042] Adamantane yield = (Amount of adamantane produced / Amount of endo-THDCPD added) × 100%, Equation (1).

[0043] In formula (1), endo-THDCPD refers to bridged tetrahydrodicyclopentadiene.

[0044] In this invention, the method for calculating the area by integration can be a method known in the art, such as calculating the area by integration using mathematical formulas and calculating the area by integration of a curve using Origin software.

[0045] In this invention, there are no special requirements for the test method and conditions of the NH3-TPD curve. Specifically, it includes: purging 0.15g of catalyst with helium for 0.5h, cooling to room temperature, adsorbing ammonia to saturation, purging with helium (30mL / min) until the baseline is stable, and heating from room temperature to 640℃ at a heating rate of 5℃ / min.

[0046] Comparative Example 1

[0047] 1. Catalyst Preparation

[0048] According to the molar ratio SiO2 / Al2O3 = 20, OH - / SiO2=0.3, Na / SiO2=0.3, TEABr / SiO2=0.05, CTAB / SiO2=0.03, H2O / SiO2=25, where TEABr represents tetraethylammonium bromide and CTAB represents hexadecyltrimethylammonium bromide. Weigh out sodium aluminate, sodium hydroxide, silica, tetraethylammonium bromide, hexadecyltrimethylammonium bromide, and deionized water.

[0049] Sodium hydroxide and sodium aluminate were dissolved separately in deionized water to prepare solutions. Silica, tetraethylammonium bromide, and hexadecyltrimethylammonium bromide were added sequentially to the prepared sodium aluminate aqueous solution. Sodium hydroxide solution was slowly added while stirring vigorously. The mixture was stirred at room temperature for 50 minutes, then transferred to a hydrothermal crystallization vessel lined with tetrafluoroethylene. The reaction was carried out at 170°C for 70 hours. After crystallization, the vessel was removed, yielding a layered mordenite molecular sieve suspension. This suspension was dried at room temperature for 18 hours, then calcined in a muffle furnace at 550°C in air for 5 hours to obtain a mesoporous layered mordenite molecular sieve. The catalyst had a specific surface area of ​​254.4 m². 2 / g, with a silicon-to-aluminum ratio of SiO2:Al2O3 molar ratio of 15.8:1, the NH3-TPD curve is as follows: Figure 1 As shown, the peak area was calculated using Origin software integration. The peak area of ​​the weak acid center was 350.71, and the peak area of ​​the strong acid center was 284.61.

[0050] 2. Synthesis reaction of adamantane

[0051] In a 100 mL magnetically stirred autoclave, 10 g of bridged tetrahydrodicyclopentadiene, 6 g of mesoporous layered mordenite molecular sieve, and 30 mL of cyclohexane were added. The mixture was purged three times with 99.99% nitrogen gas. Hydrogen gas was then introduced into the autoclave for three purgings, maintaining a pressure of 1.0 MPa. Stirring was then initiated to allow the bridged tetrahydrodicyclopentadiene to slowly dissolve. The reaction temperature was 250 °C, and the reaction time was 4 hours. After the reaction was complete, 30 mL of n-hexane was added to a three-necked flask and stirred until the adamantane was completely dissolved. The mixture was then allowed to stand for 10 minutes. The supernatant was poured into a 100 mL flask and rotary evaporated until the adamantane was completely crystallized. After air-drying at room temperature for 4 hours, 2.48 g of white crystalline adamantane with a purity of 94.5% was obtained, representing a yield of 24.8%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0052] Example 1

[0053] 1. Catalyst Preparation

[0054] A 0.5 mol / L aqueous solution of tartaric acid and citric acid was prepared at a mass ratio of 1:3. The mesoporous layered mordenite zeolite molecular sieve and the organic acid solution from Comparative Example 1 were impregnated in equal volumes. The mixture was stirred continuously at 50°C for 50 min, then stopped for 20 min, and this process was repeated four times, followed by stirring for 50 min each time. The resulting material was dried in a nitrogen atmosphere at 110°C for 12 h, and then calcined in air at 550°C in a muffle furnace for 4 h to obtain a mesoporous layered molecular sieve catalyst with acidic sites. The specific surface area of ​​this catalyst was 453.3 m². 2 / g, with a silicon-to-aluminum ratio of SiO2:Al2O3 molar ratio of 16.2:1, the NH3-TPD curve is as follows: Figure 2 As shown, the peak area was calculated using Origin software integration. The peak area of ​​the weak acid center was 383.83, and the peak area of ​​the strong acid center was 263.08.

[0055] 2. Synthesis reaction of adamantane

[0056] In a 100 mL magnetically stirred autoclave, 10 g of bridged tetrahydrodicyclopentadiene, 6 g of the aforementioned molecular sieve catalyst, and 30 mL of cyclohexane were added. The mixture was purged three times with 99.99% nitrogen gas. Hydrogen gas was then introduced into the autoclave for three purgings, maintaining the pressure inside the autoclave at 1.0 MPa. Stirring was initiated to allow the bridged tetrahydrodicyclopentadiene to slowly dissolve. The reaction temperature was 250 °C, and the reaction time was 4 hours. After the reaction was complete, 30 mL of n-hexane was added to a three-necked flask and stirred until the adamantane was completely dissolved. The mixture was then allowed to stand for 10 minutes. The supernatant was poured into a 100 mL flask and rotary evaporated until the adamantane was completely crystallized. After air-drying at room temperature for 4 hours, 3.16 g of white crystalline adamantane with a purity of 98.4% was obtained, representing a yield of 31.6%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0057] Example 2

[0058] 1. Catalyst Preparation

[0059] A 1.0 mol / L aqueous solution of tartaric acid and citric acid was prepared with a mass ratio of 1:5. This solution was then used for impregnation with an equal volume of mesoporous layered mordenite molecular sieve and organic acid solution, as described in Comparative Example 1. The impregnation, drying, and calcination processes were the same as in Example 1, yielding a mesoporous layered molecular sieve catalyst with acidic sites. This catalyst has a specific surface area of ​​485.0 m². 2 / g, with a silicon-to-aluminum ratio of SiO2:Al2O3 molar ratio of 16.6:1, the NH3-TPD curve is as follows: Figure 3 As shown, the peak areas were calculated using Origin software integration. The peak area at the weak acid center was 390.28, and the peak area at the strong acid center was 262.91. The SEM morphology of the catalyst is shown below. Figure 5 It is displayed as a layered structure.

[0060] 2. Synthesis reaction of adamantane

[0061] In a 100 mL magnetically stirred autoclave, 10 g of bridged tetrahydrodicyclopentadiene, 6 g of the aforementioned molecular sieve catalyst, and 30 mL of cyclohexane were added. The mixture was purged three times with 99.99% nitrogen gas. Hydrogen gas was then introduced into the autoclave for three purgings, maintaining the pressure inside the autoclave at 1.0 MPa. Stirring was initiated to allow the bridged tetrahydrodicyclopentadiene to slowly dissolve. The reaction temperature was 250 °C, and the reaction time was 4 hours. After the reaction was complete, 30 mL of n-hexane was added to a three-necked flask and stirred until the adamantane was completely dissolved. The mixture was then allowed to stand for 10 minutes. The supernatant was poured into a 100 mL flask and rotary evaporated until the adamantane was completely crystallized. After air-drying at room temperature for 4 hours, 3.56 g of white crystalline adamantane with a purity of 99.5% was obtained, representing a yield of 35.6%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0062] Example 3

[0063] 1. Catalyst Preparation

[0064] A 1.5 mol / L aqueous solution of tartaric acid and citric acid was prepared with a mass ratio of 1:7. The mesoporous layered mordenite zeolite molecular sieve and the organic acid solution were impregnated in equal volumes as in Comparative Example 1. The impregnation, drying, and calcination processes were the same as in Example 1, yielding a mesoporous layered molecular sieve catalyst with acidic sites. The catalyst had a specific surface area of ​​458.6 m². 2 / g, with a silicon-to-aluminum ratio of SiO2:Al2O3 molar ratio of 16.9:1, the NH3-TPD curve is as follows: Figure 4 As shown, the peak area was calculated using Origin software integration. The peak area of ​​the weak acid center was 356.93, and the peak area of ​​the strong acid center was 241.69.

[0065] 2. Synthesis reaction of adamantane

[0066] In a 100 mL magnetically stirred autoclave, 10 g of bridged tetrahydrodicyclopentadiene, 6 g of the aforementioned molecular sieve catalyst, and 30 mL of cyclohexane were added. The mixture was purged three times with 99.99% nitrogen gas. Hydrogen gas was then introduced into the autoclave for three purgings, maintaining a pressure of 1.0 MPa. Stirring was initiated to allow the bridged tetrahydrodicyclopentadiene to slowly dissolve. The reaction temperature was 250 °C, and the reaction time was 4 hours. After the reaction was complete, 30 mL of n-hexane was added to a three-necked flask and stirred until the adamantane was completely dissolved. The mixture was then allowed to stand for 10 minutes. The supernatant was poured into a 100 mL flask and rotary evaporated until the adamantane was completely crystallized. After air-drying at room temperature for 4 hours, 3.04 g of white crystalline adamantane with a purity of 97.0% was obtained, representing a yield of 30.4%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0067] Example 4

[0068] Following the method of Example 2, except that 1.0 mol / L tartaric acid was used as the organic acid, a mesoporous layered molecular sieve catalyst with acidic sites was obtained. This catalyst has a specific surface area of ​​356.8 m². 2 The silicon-to-aluminum ratio was 18.2:1 (SiO2:Al2O3 molar ratio). Peak areas were calculated using Origin software integration. The central peak area for the weak acid was 350.81, and the central peak area for the strong acid was 279.53. The reaction yielded 2.66 g of white crystalline adamantane with a purity of 96.5%, representing a yield of 26.6%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0069] Example 5

[0070] Following the method of Example 2, except that 1.0 mol / L citric acid was used as the organic acid, a mesoporous layered molecular sieve catalyst with acidic sites was obtained. This catalyst has a specific surface area of ​​427.5 m². 2 The silicon-to-aluminum ratio was 17.3:1 (SiO2:Al2O3 molar ratio). Peak areas were calculated using Origin software integration. The central peak area for the weak acid was 358.65, and the central peak area for the strong acid was 272.51. The reaction yielded 2.83 g of white crystalline adamantane with a purity of 96.6%, representing a yield of 28.3%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0071] Example 6

[0072] Following the method of Example 2, except that 1.0 mol / L acetic acid was used as the organic acid, a mesoporous layered molecular sieve catalyst with acidic sites was obtained. This catalyst has a specific surface area of ​​400.3 m². 2 The silicon-to-aluminum ratio was 19.5:1 (SiO2:Al2O3 molar ratio). Peak areas were calculated using Origin software integration. The central peak area for the weak acid was 359.63, and the central peak area for the strong acid was 280.32. The reaction yielded 2.59 g of white crystalline adamantane with a purity of 95.2%, representing a yield of 25.9%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0073] Example 7

[0074] Following the method of Example 2, except that the contact conditions were continuous stirring at 50°C for 8 hours without interruption, followed by drying the above material in a nitrogen atmosphere at 110°C for 12 hours, and then calcining it in an air atmosphere at 550°C in a muffle furnace for 4 hours to obtain a mesoporous layered molecular sieve catalyst with acidic sites. This catalyst has a specific surface area of ​​285.6 m². 2 The silicon-to-aluminum ratio was 19.8:1 (SiO2:Al2O3 molar ratio). Peak areas were calculated using Origin software integration. The central peak area for the weak acid was 352.36, and the central peak area for the strong acid was 285.63. The reaction yielded 2.53 g of white crystalline adamantane with a purity of 95.1%, representing a yield of 25.3%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0075] Example 8

[0076] The method was followed in Example 2, except that drying was carried out in an air atmosphere, while all other conditions remained the same. The catalyst had a specific surface area of ​​483.0 m². 2The silicon-to-aluminum ratio was 16.6:1 (SiO2:Al2O3 molar ratio). Peak areas were calculated using Origin software integration. The central peak area for the weak acid was 382.36, and the central peak area for the strong acid was 260.85. The reaction yielded 3.26 g of white crystalline adamantane with a purity of 99.0%, representing a yield of 32.6%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0077] Example 9

[0078] The method was followed in Example 2, except that calcination was carried out under a nitrogen atmosphere, while all other conditions remained the same. The catalyst had a specific surface area of ​​481.4 m². 2 The silicon-to-aluminum ratio was 16.6:1 (SiO2:Al2O3 molar ratio). Peak areas were calculated using Origin software integration. The central peak area for the weak acid was 372.36, and the central peak area for the strong acid was 256.58. The reaction yielded 3.23 g of white crystalline adamantane with a purity of 98.6%, representing a yield of 32.3%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0079] Example 10

[0080] Following the method of Example 2, except that toluene was used as the organic solvent, the reaction yielded 2.03 g of white crystalline adamantane with a purity of 92.7%, representing a yield of 20.3%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0081] Example 11

[0082] Following the method of Example 2, except that the reaction pressure was atmospheric pressure, the reaction temperature was 350°C, and the reaction time was 6 hours, the reaction yielded 0.36 g of white crystalline adamantane with a purity of 80.7%, and the yield of adamantane was 3.6%. For ease of explanation and comparison, the reaction results are listed in Table 1.

[0083] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

[0084] Table 1

[0085]

[0086] If the data records in the table differ from those in the embodiment, the embodiment shall prevail.

Claims

1. A method for preparing adamantane, characterized in that, The method includes: isomerizing tetrahydrodicyclopentadiene in the presence of a mesoporous mordenite molecular sieve catalyst with acidic sites established by organic acids, in the presence of an optional organic solvent, and under a hydrogen-containing atmosphere; determining the NH3-TPD peak area of ​​the catalyst by integration; wherein the weak acid center peak area of ​​the catalyst is above 330, the strong acid center peak area is below 282, and the specific surface area of ​​the catalyst is above 300 m². 2 / g or more, the silicon-to-aluminum ratio of the catalyst is (10~30):1 in terms of the SiO2:Al2O3 molar ratio, and the preparation method of the catalyst includes: contacting an organic acid aqueous solution with a mesoporous mordenite molecular sieve, and drying and calcining the obtained solid.

2. The method according to claim 1, wherein, The catalyst has a weak acid central peak area of ​​351-395 and a strong acid central peak area of ​​240-264; and / or The catalyst has a layered structure in its microstructure; and / or The catalyst has a specific surface area of ​​300~600m². 2 / g.

3. The method according to claim 2, wherein, The silicon-to-aluminum ratio of the catalyst is (16~20):1, expressed as a SiO2:Al2O3 molar ratio; and / or The catalyst has a specific surface area of ​​400~500 m². 2 / g.

4. The method according to claim 1, wherein, The mesoporous silicalite molecular sieve is a mesoporous layered silicalite molecular sieve and / or a mesoporous nano silicalite molecular sieve.

5. The method according to claim 1, wherein, Contact conditions include: intermittent stirring at a temperature of 20℃~80℃ for 2h~8h; and / or The drying conditions include: drying temperature of 70℃~120℃ under an inert atmosphere; drying time of 8h~16h; and / or The roasting conditions include: roasting temperature of 350℃~550℃ in an oxygen-containing atmosphere; and roasting time of 2h~6h.

6. The method according to claim 5, wherein, Contact conditions include: intermittent stirring at 40℃~60℃ for 2h~8h; and / or The drying conditions include: drying at 100℃~110℃ under an inert atmosphere; drying time of 10h~12h; and / or The calcination conditions include: calcination temperature of 500℃~550℃ in an oxygen-containing atmosphere; and calcination time of 4h~5h.

7. The method according to claim 5, wherein, The contact conditions include: an interval of 10 to 30 minutes after each stirring, followed by the next stirring.

8. The method according to claim 7, wherein, Contact conditions include: repeated stirring - with 3 to 5 intermittent stirring intervals, and each stirring session lasting 30 to 60 minutes.

9. The method according to claim 5, wherein, The inert atmosphere is a nitrogen atmosphere, and the oxygen-containing atmosphere is an air atmosphere.

10. The method according to claim 1, wherein, The concentration of the organic acid aqueous solution is 0.1 mol / L to 3 mol / L; and / or The contact is an equal-volume impregnation contact.

11. The method according to claim 10, wherein, The concentration of the organic acid aqueous solution is 0.5 mol / L ~ 1.5 mol / L.

12. The method according to claim 1, wherein, The organic acid is selected from one or more of citric acid, tartaric acid, acetic acid, oxalic acid, and glycolic acid.

13. The method according to claim 12, wherein, The organic acid is a mixture of citric acid and tartaric acid, with a mass ratio of tartaric acid to citric acid of 1:2~8.

14. The method according to claim 13, wherein, The organic acid is a mixture of citric acid and tartaric acid, with a mass ratio of tartaric acid to citric acid of 1:3~7.

15. The method according to claim 1, wherein, The method includes: In the presence of a mesoporous mordenite molecular sieve catalyst with acidic sites established by organic acids, tetrahydrodicyclopentadiene dissolved in an organic solvent is isomerized under a hydrogen-containing atmosphere.

16. The method according to claim 1, wherein, The method includes: the organic solvent being selected from one or more of cyclohexane, methylcyclohexane, ethylcyclohexane, diethylcyclohexane, and methylethylcyclohexane.

17. The method according to any one of claims 1-16, wherein, The conditions for isomerization reactions include: The reaction temperature is 180℃~300℃; and / or Hydrogen pressure is 0.5 MPa to 2.5 MPa; and / or The reaction time is 1 hour to 9 hours.

18. The method according to claim 17, wherein, The conditions for isomerization reactions include: The reaction temperature is 200℃~300℃; and / or Hydrogen pressure is 0.5 MPa to 2 MPa; and / or The reaction time is 3 to 7 hours.

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