Process for the synthesis of adamantane
By employing a two-step isomerization process and appropriate catalyst design, the problems of low yield and poor catalyst stability in existing adamantane production have been solved, achieving adamantane production with high yield and low by-products, which is environmentally friendly.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-28
- Publication Date
- 2026-05-29
AI Technical Summary
Existing methods for producing adamantane suffer from low yield, poor catalyst stability, high waste emissions, and easy equipment corrosion, especially in the aluminum trichloride process and zeolite process.
A two-step isomerization process was adopted, using first and second isomerization catalysts with different amounts of medium-strong acid, namely the first isomerization catalyst and the second isomerization catalyst. The initial conversion of tetrahydrodicyclopentadiene was carried out under the first isomerization catalyst, followed by further conversion under the second isomerization catalyst. By combining appropriate reaction conditions and purification steps, the yield of adamantane and the stability of the catalyst were improved.
It achieves high yield of adamantane and low by-product formation, with good catalyst stability, environmental friendliness, and reduced equipment corrosion and waste emissions.
Abstract
Description
Technical Field
[0001] This invention relates to the field of adamantane synthesis, and more specifically to a method for synthesizing adamantane. Background Technology
[0002] Adamantane is a periodically symmetrical and highly stable cage-like hydrocarbon with potential applications in pharmaceuticals, functional polymers, surfactants, lubricants, and photographic materials, thus earning it the reputation of a new generation of fine chemical raw materials. According to GIR (Global Info Research), global adamantane revenue was approximately US$140 million in 2022 and is projected to reach US$270 million by 2029, representing a CAGR of 9.6% from 2023 to 2029. my country is the world's most important producer of adamantane and its derivatives, with existing production capacity of approximately 8,500 tons per year and new capacity of 5,000 tons per year as of 2023.
[0003] Currently, the reported production methods for adamantane include the aluminum trichloride method and the zeolite method. Apart from Idemitsu Corporation of Japan, which reported an application case of the zeolite method for adamantane production, other companies all use the aluminum trichloride method. After years of technological improvements, the domestic aluminum trichloride method has become increasingly mature, and the overall yield of adamantane has gradually increased. However, this process still suffers from drawbacks such as equipment corrosion, difficulty in catalyst recovery and utilization, high energy consumption in adamantane purification, and high levels of waste emissions, which urgently need to be addressed in the industry's development.
[0004] Compared to the aluminum trichloride method, the zeolite method for adamantane production offers easier separation of the product from the catalyst, and the catalyst can be recycled, significantly reducing emissions of waste gas, wastewater, and solid waste, as well as separation energy consumption. Idemitsu Corporation of Japan, in its CN102066292A zeolite-based adamantane production process, uses 0.75% Pt-0.25% Re-3% Co / ReY as a catalyst. Under conditions of 250℃ and 1.6 MPa (H2 pressure 1.5 MPa, HCl pressure 0.1 MPa) for 2.5 hours, the adamantane yield reaches 31%. It uses bridged tetrahydrodicyclopentadiene as a raw material, converting it to hanging tetrahydrodicyclopentadiene under fixed reaction conditions, which is then further converted to adamantane. While the Idemitsu method provides a green synthesis process for adamantane, it suffers from low adamantane yield (the highest level is only 34%), high tar production, and poor catalyst stability. Summary of the Invention
[0005] The purpose of this invention is to overcome the problems of low adamantane yield, poor catalyst stability, high waste emissions, and easy equipment corrosion in the existing technology, and to provide a method for synthesizing adamantane with high adamantane yield, few by-products, good catalyst stability, and environmental and equipment friendliness.
[0006] The method for synthesizing adamantane provided by this invention is described in detail below. It should be understood that the description herein is for illustrative and explanatory purposes only and is not intended to limit the invention. 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.
[0007] This invention provides a method for synthesizing adamantane, comprising: performing a first isomerization on tetrahydrodicyclopentadiene in the presence of a first isomerization catalyst, followed by a second isomerization in the presence of a second isomerization catalyst, wherein the amount of moderately strong acid in the first isomerization catalyst is lower than that in the second isomerization catalyst. This synthetic method, possessing the aforementioned characteristics, results in high adamantane yield, few byproducts, good catalyst stability, and is environmentally and equipment-friendly.
[0008] According to a preferred embodiment of the present invention, the amount of moderately strong acid in the second isomerization catalyst is 0.5-1.5 mmol / g higher than that in the first isomerization catalyst. The synthesis method with the aforementioned characteristics results in a higher adamantane yield, fewer byproducts, and better catalyst stability.
[0009] In this invention, the amount of moderately strong acid in the first isomerization catalyst can be selected from a wide range, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the amount of moderately strong acid in the first isomerization catalyst is 0.1-1 mmol / g. For example, it can be 0.2 mmol / g, 0.4 mmol / g, 0.6 mmol / g, or 0.8 mmol / g.
[0010] In this invention, the objective of the invention can be achieved by using a first isomerization catalyst that meets the aforementioned acid content. There are no special requirements for its source. For example, the first isomerization catalyst with the aforementioned acid content can be prepared by acid treatment or alkali treatment of the active component and then loading it onto the support.
[0011] According to a preferred embodiment of the present invention, the first isomerization catalyst comprises a first active component and a first support.
[0012] In this invention, the type of the first active component is not particularly limited; any suitable type can be selected as long as it achieves the purpose of this invention. According to a preferred embodiment of the invention, the first active component includes Pt, and optionally one or more of Re, Co, Ce, La, In, and Y.
[0013] In this invention, the type of the first carrier is not particularly limited; any suitable type can be selected as long as it achieves the purpose of this invention. According to a preferred embodiment of the invention, the first carrier is a twelve-membered ring molecular sieve, preferably selected from one or more of mordenite, β-zeolite, and MWW zeolite.
[0014] In this invention, the content of the first active component in the first isomerization catalyst can be selected within a wide range. The following is an illustrative example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the content of the first active component, based on the total weight of the first isomerization catalyst and calculated as oxides, is 0.01-1 wt%. For example, it can be 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, or 0.8 wt%.
[0015] The first isomerization catalyst with the aforementioned characteristics can promote steric isomerization, resulting in higher adamantane yield, fewer byproducts, and better catalyst stability.
[0016] In this invention, the amount of moderately strong acid in the second isomerization catalyst can be selected from a wide range, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the amount of moderately strong acid in the second isomerization catalyst is 1-2.5 mmol / g. For example, it can be 1.2 mmol / g, 1.4 mmol / g, 1.6 mmol / g, 1.8 mmol / g, 2.0 mmol / g, 2.2 mmol / g, or 2.4 mmol / g.
[0017] In this invention, the objective of the invention can be achieved by using a second isomerization catalyst that meets the aforementioned acid content. There are no special requirements for its source. For example, the second isomerization catalyst with the aforementioned acid content can be prepared by acid treatment or alkali treatment of the active component and then loading it onto the support.
[0018] According to a preferred embodiment of the present invention, the second isomerization catalyst comprises a second active component and a second support.
[0019] In this invention, the type of the second active component is not particularly limited; any suitable type can be selected as long as it achieves the purpose of this invention. According to a preferred embodiment of the invention, the second active component includes Pt, and optionally one or more of Re, Co, Ce, La, In, and Y.
[0020] In this invention, the type of the second carrier is not particularly limited; any suitable type can be selected as long as it achieves the purpose of this invention. According to a preferred embodiment of this invention, the second carrier is selected from one or more of β-zeolite, MWW zeolite, and Y-type zeolite.
[0021] In this invention, the content of the second active component in the second isomerization catalyst can be selected within a wide range. The following is an illustrative example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the content of the second active component, based on the total weight of the second isomerization catalyst and calculated as oxides, is 0.35-1 wt%. For example, it can be 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, or 0.9 wt%.
[0022] The second isomerization catalyst with the aforementioned characteristics can promote skeletal isomerization, resulting in higher adamantane yield, fewer byproducts, and better catalyst stability.
[0023] In this invention, there is no particular limitation on the type of tetrahydrodicyclopentadiene; any suitable type can be selected as long as it achieves the purpose of this invention. According to a preferred embodiment of this invention, tetrahydrodicyclopentadiene includes hanging tetrahydrodicyclopentadiene and / or bridged tetrahydrodicyclopentadiene, preferably including hanging tetrahydrodicyclopentadiene and bridged tetrahydrodicyclopentadiene.
[0024] In this invention, the content of the hanging tetrahydrodicyclopentadiene in tetrahydrodicyclopentadiene has a wide range of selectable values. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the content of the hanging tetrahydrodicyclopentadiene, based on the total weight of tetrahydrodicyclopentadiene, is 20-50 wt%. For example, it can be 25 wt%, 30 wt%, 35 wt%, 40 wt%, or 45 wt%.
[0025] In this invention, the content of bridging tetrahydrodicyclopentadiene in tetrahydrodicyclopentadiene has a wide selectable range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the content of bridging tetrahydrodicyclopentadiene, based on the total weight of tetrahydrodicyclopentadiene, is 50-80 wt%. For example, it can be 55 wt%, 60 wt%, 65 wt%, 70 wt%, or 75 wt%.
[0026] According to a preferred embodiment of the present invention, the conditions of the first isomerization are controlled such that after the first isomerization is completed, the conversion rate of tetrahydrodicyclopentadiene is controlled to be within 90%, preferably 60-90%.
[0027] The synthetic method with the aforementioned characteristics has the advantages of high total yield of adamantane, low yield of by-products, and good catalyst stability.
[0028] In this invention, the temperature range for the first isomerization is relatively wide, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the temperature for the first isomerization is 200-400°C.
[0029] In this invention, the pressure range for the first isomerization is relatively wide, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the pressure for the first isomerization is 1.5-2.5 MPa.
[0030] According to a preferred embodiment of the present invention, in the first isomerization, hydrogen gas is introduced into the reactor.
[0031] In this invention, the volume ratio of hydrogen to tetrahydrodicyclopentadiene in the first isomerization can be selected within a wide range, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the volume ratio of hydrogen to tetrahydrodicyclopentadiene in the first isomerization is 300-1000:1.
[0032] In this invention, the mass hourly space velocity (MHSV) of the first isomerization can be selected from a wide range, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the MHSV of the first isomerization is 2-4 h. -1 .
[0033] The first isomerization with the aforementioned characteristics has the advantages of high conversion rate, high selectivity and low by-product yield.
[0034] In this invention, the temperature range for the second isomerization is relatively wide, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the temperature for the second isomerization is 200-400°C.
[0035] In this invention, the pressure range for the second isomerization is relatively wide, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the pressure for the second isomerization is 1-2.5 MPa.
[0036] According to a preferred embodiment of the present invention, in the second isomerization, hydrogen gas is introduced into the reactor.
[0037] In this invention, the volume ratio of hydrogen to tetrahydrodicyclopentadiene in the second isomerization can be selected within a wide range, as illustrated below, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the volume ratio of hydrogen to tetrahydrodicyclopentadiene in the second isomerization is 300-1000:1.
[0038] In this invention, the mass hourly space velocity (MHSV) of the second isomerization can be selected from a wide range. The following is an illustrative example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the MHSV of the second isomerization is 2-4 h. -1 .
[0039] The second isomerization with the aforementioned characteristics has the advantages of high conversion rate, high selectivity and low by-product yield.
[0040] According to a preferred embodiment of the present invention, the method for synthesizing adamantane further includes: purifying the liquid phase product of the second isomerization to obtain adamantane, and returning the purified liquid phase raw material to the first isomerization as a raw material.
[0041] According to a preferred embodiment of the present invention, the purification includes the steps of solvent removal, crystallization, and washing.
[0042] In this invention, the type of reactor for the first isomerization is not particularly limited; any suitable type can be selected as long as it achieves the purpose of this invention. According to a preferred embodiment of the invention, the first isomerization is carried out in a continuous reactor or a batch reactor.
[0043] In this invention, the type of reactor for the second isomerization is not particularly limited; any suitable type can be selected as long as it achieves the purpose of this invention. According to a preferred embodiment of the invention, the second isomerization is carried out in a continuous reactor or a batch reactor.
[0044] The method for synthesizing adamantane provided by this invention has the advantages of high adamantane yield, few by-products, good catalyst stability, no use of hydrochloric acid, and environmental and equipment friendliness. Detailed Implementation
[0045] The present invention will be described in detail below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.
[0046] For any experimental steps or conditions not specified in the examples and comparative examples, the procedures or conditions described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.
[0047] In the examples and comparative examples,
[0048] The first and second isomerizations are carried out independently in a fixed-bed reactor;
[0049] The acidity was tested using the n-butylamine titration method;
[0050] Tetrahydrodicyclopentadiene conversion rate = 100% × (tetrahydrodicyclopentadiene content in feedstock wt% - tetrahydrodicyclopentadiene content in product wt%) / tetrahydrodicyclopentadiene content in feedstock wt%;
[0051] Adamantane yield = Adamantane content in the product (wt%) × tetrahydrodicyclopentadiene conversion rate.
[0052] Example 1
[0053] Tetrahydrodicyclopentadiene (20 wt% of hook-type tetrahydrodicyclopentadiene and 80 wt% of bridge-type tetrahydrodicyclopentadiene) underwent a first isomerization. The active components of the first isomerization catalyst were Pt and Y, supported by MWW zeolite. Based on oxides, the active components Pt accounted for 0.2 wt% and Y for 0.1 wt%, and the medium-strong acid content of the first isomerization catalyst was 0.6 mmol / g. The first isomerization was performed at 300 °C, 1.6 MPa, with a hydrogen to tetrahydrodicyclopentadiene volume ratio of 600:1 and a mass hourly space velocity (HHSV) of 2 h⁻¹. -1 After 12 hours of reaction, following the first isomerization, the conversion rate of tetrahydrodicyclopentadiene was 83%. After 120 hours of reaction, following the first isomerization, the conversion rate of tetrahydrodicyclopentadiene was 79%.
[0054] A second isomerization was then performed. The active components of the second isomerization catalyst were Pt and Co, and the support was Y-type zeolite. As oxides, the active components Pt accounted for 0.7 wt% and Co for 0.1 wt%. The medium-strong acid content of the second isomerization catalyst was 1.4 mmol / g. The second isomerization temperature was 280 °C, the pressure was 1.4 MPa, the volume ratio of hydrogen to tetrahydrodicyclopentadiene was 800:1, and the mass hourly space velocity (HHSV) was 2 h⁻¹. -1 The liquid product was crystallized at 10°C, and the resulting solid product was washed to obtain adamantane. After 12 hours of reaction, the yield of adamantane was 38% with a purity of 99.8%. After 120 hours of reaction, the yield of adamantane was 36% with a purity of 97.6%.
[0055] Example 2
[0056] Tetrahydrodicyclopentadiene (20 wt% of hook-type tetrahydrodicyclopentadiene and 80 wt% of bridge-type tetrahydrodicyclopentadiene) underwent a first isomerization. The active components of the first isomerization catalyst were Pt and Y, supported by MWW zeolite. As oxides, the active components Pt and Y accounted for 0.1 wt%, and the medium-strong acid content of the first isomerization catalyst was 0.8 mmol / g. The first isomerization was performed at 300 °C, 1.6 MPa, with a hydrogen to tetrahydrodicyclopentadiene volume ratio of 600:1 and a mass hourly space velocity (HHSV) of 2 h⁻¹. -1 After 12 hours of reaction, following the completion of the first isomerization, the conversion rate of tetrahydrodicyclopentadiene was 80%. After 120 hours of reaction, following the completion of the first isomerization, the conversion rate of tetrahydrodicyclopentadiene was 76%.
[0057] A second isomerization was then performed. The active components of the second isomerization catalyst were Pt and Co, and the support was Y-type zeolite. As oxides, the active components Pt accounted for 0.4 wt% and Co for 0.1 wt%. The medium-strong acid content of the second isomerization catalyst was 1.6 mmol / g. The second isomerization temperature was 280 °C, the pressure was 1.4 MPa, the volume ratio of hydrogen to tetrahydrodicyclopentadiene was 800:1, and the mass hourly space velocity (HHSV) was 2 h⁻¹. -1 The liquid product was crystallized at 10°C, and the resulting solid product was washed to obtain adamantane. After 12 hours of reaction, the yield of adamantane was 35% with a purity of 99.8%. After 120 hours of reaction, the yield of adamantane was 32% with a purity of 98.3%.
[0058] Example 3
[0059] Tetrahydrodicyclopentadiene (20 wt% of hook-type tetrahydrodicyclopentadiene and 80 wt% of bridge-type tetrahydrodicyclopentadiene) underwent a first isomerization. The active components of the first isomerization catalyst were Pt and Y, supported on mordenite. Based on oxides, the active components Pt accounted for 0.2 wt% and Y for 0.1 wt%, and the medium-strong acid content of the first isomerization catalyst was 0.6 mmol / g. The first isomerization was performed at 300 °C, 1.6 MPa, with a hydrogen to tetrahydrodicyclopentadiene volume ratio of 600:1 and a mass hourly space velocity (HHSV) of 2 h⁻¹. -1 After 12 hours of reaction, following the completion of the first isomerization, the conversion rate of tetrahydrodicyclopentadiene was 78%. After 120 hours of reaction, following the completion of the first isomerization, the conversion rate of tetrahydrodicyclopentadiene was 75%.
[0060] A second isomerization was then performed. The active components of the second isomerization catalyst were Pt and Co, and the support was MWW zeolite. As oxides, the active components Pt accounted for 0.7 wt% and Co accounted for 0.1 wt%. The medium-strong acid content of the second isomerization catalyst was 1.4 mmol / g. The second isomerization temperature was 280 °C, the pressure was 1.4 MPa, the volume ratio of hydrogen to tetrahydrodicyclopentadiene was 800:1, and the mass hourly space velocity (HHSV) was 2 h⁻¹. -1 The liquid product was crystallized at 10°C, and the resulting solid product was washed to obtain adamantane. After 12 hours of reaction, the yield of adamantane was 34% with a purity of 99.7%. After 120 hours of reaction, the yield of adamantane was 32% with a purity of 98.4%.
[0061] Example 4
[0062] Following the method of Example 1, except that the amount of moderately strong acid in the first isomerization catalyst was 1.2 mmol / g, after 12 h of reaction, the conversion rate of tetrahydrodicyclopentadiene was 80% after the first isomerization; after 120 h of reaction, the conversion rate of tetrahydrodicyclopentadiene was 74% after the first isomerization. After 12 h of reaction, the yield of adamantane was 34% with a purity of 99.8%. After 120 h of reaction, the yield of adamantane was 30% with a purity of 97.2%.
[0063] Example 5
[0064] The method was followed as in Example 1, except that the amount of moderately strong acid in the second isomerization catalyst was 0.8 mmol / g. After 12 h of reaction, the yield of adamantane was 36% with a purity of 99.0%. After 120 h of reaction, the yield of adamantane was 31% with a purity of 97.5%.
[0065] Example 6
[0066] Following the method of Example 1, except that the composition of the starting material tetrahydrodicyclopentadiene was different, consisting of 30 wt% of bridging tetrahydrodicyclopentadiene and 70 wt% of bridged tetrahydrodicyclopentadiene. After 12 hours of reaction, following the first isomerization, the conversion rate of tetrahydrodicyclopentadiene was 68%; after 120 hours of reaction, following the first isomerization, the conversion rate of tetrahydrodicyclopentadiene was 65%. After 12 hours of reaction, the yield of adamantane was 41%, with a purity of 99.6%. After 120 hours of reaction, the yield of adamantane was 38%, with a purity of 98.5%.
[0067] Example 7
[0068] The method is the same as in Example 1, except that the first isomerization temperature is 320°C, the pressure is 1.8 MPa, the volume ratio of hydrogen to tetrahydrodicyclopentadiene is 700:1, and the mass hourly space velocity is 3 h⁻¹. -1 After 12 hours of reaction, the conversion rate of tetrahydrodicyclopentadiene was 85% after the first isomerization. After 120 hours of reaction, the conversion rate of tetrahydrodicyclopentadiene was 81% after the first isomerization. The second isomerization temperature was 300℃, the pressure was 1.6 MPa, the volume ratio of hydrogen to tetrahydrodicyclopentadiene was 600:1, and the mass hourly space velocity (HHSV) was 4 h⁻¹. -1 After 12 hours of reaction, the yield of adamantane was 36% with a purity of 99.0%. After 120 hours of reaction, the yield of adamantane was 33% with a purity of 98.1%.
[0069] Comparative Example 1
[0070] The method of Example 1 was followed, except that a single isomerization was performed under the conditions for the first isomerization. After 12 hours of reaction, the yield of adamantane was 28% with a purity of 96.7%. After 120 hours of reaction, the yield of adamantane was 17% with a purity of 85.7%.
[0071] Comparative Example 2
[0072] The method of Example 1 was followed, except that the first and second isomerization catalysts were exchanged. After 12 hours of reaction, the yield of adamantane was 30% with a purity of 98.6%. After 120 hours of reaction, the yield of adamantane was 17% with a purity of 86.2%.
[0073] The method for synthesizing adamantane provided by the present invention has 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 solution of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, 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.
Claims
1. A method for synthesizing adamantane, characterized in that, The method includes: performing a first isomerization on tetrahydrodicyclopentadiene in the presence of a first isomerization catalyst, followed by a second isomerization in the presence of a second isomerization catalyst, wherein the amount of medium-strong acid in the first isomerization catalyst is lower than the amount of medium-strong acid in the second isomerization catalyst.
2. The method according to claim 1, wherein, The first isomerization catalyst has a moderately strong acid content of 0.1-1 mmol / g; and / or The amount of moderately strong acid in the second isomerization catalyst is 1-2.5 mmol / g.
3. The method according to claim 1 or 2, wherein, The first isomerization catalyst includes a first active component and a first support. in, The first active component includes Pt, and optionally one or more of Re, Co, Ce, La, In, and Y. The first carrier is a twelve-membered ring molecular sieve, preferably selected from one or more of mordenite, β-zeolite, and MWW zeolite; Preferably, the content of the first active component, based on the total weight of the first isomerization catalyst and calculated as oxides, is 0.01-1 wt%.
4. The method according to any one of claims 1-3, wherein, The second isomerization catalyst includes a second active component and a second support. in, The second active component includes Pt, and optionally one or more of Re, Co, Ce, La, In, and Y. The second carrier is selected from one or more of β zeolite, MWW zeolite, and Y-type zeolite; Preferably, the content of the second active component, based on the total weight of the second isomerization catalyst and calculated as oxides, is 0.35-1 wt%.
5. The method according to any one of claims 1-4, wherein, Tetrahydrodicyclopentadiene includes hanging tetrahydrodicyclopentadiene and / or bridged tetrahydrodicyclopentadiene; Preferably, it includes hanging tetrahydrodicyclopentadiene and bridged tetrahydrodicyclopentadiene; More preferably, based on the total weight of tetrahydrodicyclopentadiene, the content of hanging tetrahydrodicyclopentadiene is 20-50 wt%, and the content of bridged tetrahydrodicyclopentadiene is 50-80 wt%.
6. The method according to any one of claims 1-5, wherein, The conditions for the first isomerization are controlled such that after the first isomerization, the conversion rate of tetrahydrodicyclopentadiene is controlled to be within 90%, preferably 60-90%.
7. The method according to any one of claims 1-6, wherein, The conditions for the first isomerization include: Temperatures of 200-400℃; and / or Pressure is 1.5-2.5 MPa; and / or The volume ratio of hydrogen to tetrahydrodicyclopentadiene is 300-1000:1; and / or Mass air velocity is 2-4h -1 .
8. The method according to any one of claims 1-7, wherein, The conditions for the second isomerization include: Temperatures of 200-400℃; and / or Pressure is 1-2.5 MPa; and / or The volume ratio of hydrogen to tetrahydrodicyclopentadiene is 300-1000:1; and / or Mass air velocity is 2-4h -1 .
9. The method according to any one of claims 1-8, wherein, The method further includes: purifying the liquid phase product of the second isomerization to obtain adamantane, and returning the purified liquid phase raw material to the first isomerization as a raw material.
10. The method according to claim 9, wherein, Purification includes the following steps: solvent removal, crystallization, and washing.