A method for continuously preparing exo-tetrahydrodicyclopentadiene

Abstract

The present application relates to a kind of methods for continuously preparing hanging tetrahydrodicyclopentadiene.The method comprises the following steps: first, bridge type tetrahydrodicyclopentadiene is mixed with reaction solvent uniformly, then impurities are removed by pretreatment, and then it flows into the upper end of the fixed bed reactor and flows out from the lower end;hydrogenation catalyst is loaded in the upper end of the fixed bed reactor, inert material is used to separate the middle part, and isomerization catalyst is loaded in the lower end;by the protection of hydrogenation catalyst in the upper end to isomerization catalyst in the lower end, bridge type tetrahydrodicyclopentadiene can be converted into hanging tetrahydrodicyclopentadiene, the conversion rate is greater than 86%, and the selectivity of target product is greater than 94%.The method is clean and green, and can realize continuous operation for more than 2000h, so it has industrial application prospect.

Description

Technical Field

[0001] The present invention relates to a method for preparing hydrocarbons, in particular to a method for preparing exo-tetrahydrodicyclopentadiene. Background Art

[0002] Dicyclopentadiene (DCPD) is mainly derived from the C5 fraction produced as a by-product of the petroleum cracking process to produce ethylene and the light benzene fraction produced as a by-product of coal coking. It is a dimer of cyclopentadiene and an important chemical intermediate. It is widely used in the synthesis of unsaturated polyester polymers, the preparation of high-density aviation fuels, and the preparation of medical materials. Its fully hydrogenated product, endotetrahydrodicyclopentadiene (Endo-THDCPD), is a solid high-density fuel with excellent performance, but it cannot be used as a liquid fuel. Its isomerized product, exo-tetrahydrodicyclopentadiene (Exo-THDCPD, JP-10), has a higher density (0.94 g / cm -3 ), a low freezing point (-79°C), a high volumetric calorific value (39.4MJ / L), and low toxicity. It can be used alone or in combination. It is a liquid fuel with excellent overall performance and has been widely studied and applied in the field of aviation fuel. The common Exo-THDCPD preparation process is a two-step conversion process in which DCPD is first hydrogenated to produce endohedral tetrahydrodicyclopentadiene (Endo-THDCPD), which is then isomerized to Exo-THDCPD.

[0003]

[0004] The hydrogenation process is relatively mature and can be completed using common supported hydrogenation catalysts or Raney nickel catalysts. However, the industrial isomerization process still needs to be carried out intermittently using highly toxic and highly polluting AlCl3 as a catalyst, and continuous industrial production has not yet been achieved. As described in patent CN 102924216B, the isomerization conversion process still requires AlCl3 as a catalyst, resulting in low Exo-THDCPD yield, high cost, and severe pollution during the production process, limiting its large-scale application.

[0005] In addition, although some studies have used molecular sieves as isomerization catalysts, such as patent CN 101786936B, which uses Y, Beta, mordenite, Al-MCM-41, Al-MCM-48, Al-SBA-15, etc. as isomerization catalysts, only the conversion rate of the raw materials and the yield of the products were examined. The catalyst life and whether it can be scaled up for continuous production were not addressed. Therefore, it does not yet have practical application capabilities. Summary of the Invention

[0006] The present invention aims to solve the problem that the existing industry cannot continuously and stably produce exo-tetrahydrodicyclopentadiene and provides a method for continuously producing exo-tetrahydrodicyclopentadiene over a long period in a fixed bed reactor.

[0007] The present invention provides a method for continuously preparing exo-tetrahydrodicyclopentadiene, comprising:

[0008] The bridged tetrahydrodicyclopentadiene and the reaction solvent are introduced into a pretreatment reactor containing an adsorbent for pretreatment, and the effluent is introduced into a fixed-bed reactor for a hydrogenation isomerization reaction to obtain the bridged tetrahydrodicyclopentadiene. The fixed-bed reactor has a hydrogenation protective agent in the upper section, an inert material in the middle section, and an isomerization catalyst in the lower section.

[0009] The bridged tetrahydrodicyclopentadiene can be prepared according to various methods disclosed in the prior art, or can be purchased commercially.

[0010] The reaction solvent is a hydrocarbon with a boiling point of 40°C to 200°C, such as cyclohexane, methylcyclohexane, dichloromethane, etc., preferably a C6-C10 hydrocarbon, such as cyclohexane and methylcyclohexane; after the bridged tetrahydrodicyclopentadiene is mixed with the reaction solvent, the mass concentration of the bridged tetrahydrodicyclopentadiene is 10%-80%, preferably 30%-60%.

[0011] The function of the pretreatment reactor is to make the solid material fully contact with the liquid, and it can be a fixed bed reactor or a quartz glass tube, etc.

[0012] The adsorbent may be activated clay, NaY molecular sieve, HY molecular sieve, activated carbon or other materials that can adsorb polar compounds, preferably activated clay and NaY molecular sieve.

[0013] The pretreatment temperature is room temperature - 60 ° C, the pretreatment pressure is 0.1-0.5 MPa, and the adsorbent treatment space velocity is 0.1-5.0h -1 .

[0014] The hydrogenation protective agent is a conventional supported metal hydrogenation catalyst, the active metal is selected from one or more of Pd, Pt, Ru, Rh, and Ni, and the carrier is selected from non-acidic carriers such as Al2O3, SiO2, ZrO2, TiO2, CeO2, and activated carbon.

[0015] The isomerization catalyst is a molecular sieve-supported metal catalyst, wherein the active metal is selected from one or more of Pd, Pt, Ru, Rh, and Ni, preferably Pt or Pd; the molecular sieve is a Y-type molecular sieve, such as HY, USY, REHY, NEY, SSY, etc., preferably HY, USY, and REHY.

[0016] The molecular sieve-supported metal catalyst can be prepared by conventional methods, such as the equal volume impregnation method, the excess volume impregnation method, etc. Specifically, a certain amount of metal precursor solution is prepared according to the metal loading, then impregnated onto the molecular sieve, and allowed to stand at room temperature for more than 6 hours with intermittent stirring during the process. It is then dried at 80°C for more than 12 hours, and then calcined at 450°C-550°C in an air atmosphere for 2 hours-5 hours. The calcined catalyst is reduced in a reducing atmosphere, such as hydrogen, at 400°C-550°C for 2 hours-5 hours to obtain an activated catalyst.

[0017] The inert material is selected from SiO2, Al2O3, carbon material, quartz sand, etc., preferably quartz sand.

[0018] In the fixed bed reactor, the temperature of the upper hydrogenation reaction is 100°C-200°C, preferably 130°C-170°C; the temperature of the lower isomerization reaction is 100°C-180°C, preferably 130°C-170°C.

[0019] In a fixed bed reactor, the system reaction pressure is 0.1MPa-3MPa hydrogen, preferably 0.5MPa-1.0MPa hydrogen. The mass space velocity is 0.5h -1 -5h -1 , preferably 0.5h -1 -2h -1 The volume ratio of hydrogen to hydrocarbon is 100-1600, preferably 600-1200.

[0020] In the present invention, the function of the hydrogenation protective agent is to remove impurities such as trace olefins and activated hydrogen from the raw material bridged tetrahydrodicyclopentadiene by hydrogenation, thereby protecting the isomerization catalyst, inhibiting its coking and extending its service life.

[0021] In the present invention, the isomerization reaction is completed by a metal / molecular sieve supported catalyst, which has the dual functions of isomerization and coking inhibition. By loading the metal on the molecular sieve, the generation of coking precursors (olefin intermediates) is inhibited.

[0022] The method of the present invention significantly improves the service life and process stability of the isomerization catalyst by pretreating the raw materials and adding a hydrogenation protective agent to the upper section of the fixed bed to protect the isomerization catalyst in the lower section. This achieves green, continuous and stable preparation of exo-tetrahydrodicyclopentadiene, with a conversion rate of greater than 86% and a target product selectivity of greater than 94%. Continuous operation of more than 2000 hours can be achieved, and the method has industrial application prospects. DETAILED DESCRIPTION

[0023] The present invention provides a method for continuously preparing hanging tetrahydrodicyclopentadiene, comprising: first, uniformly mixing bridged tetrahydrodicyclopentadiene with a reaction solvent, passing the mixture into a pretreatment reactor, removing impurities through adsorption by an adsorbent such as activated clay and NaY, and then flowing into a fixed bed reactor from the upper end and out from the lower end. In the fixed bed reactor, a hydrogenation protective agent is loaded into the upper section, the middle section is separated by an inert material, and an isomerization catalyst is loaded into the lower section. The hydrogenation reaction temperature in the upper section is 100°C-200°C; the isomerization reaction temperature in the lower section is 100°C-180°C. The entire fixed bed reaction pressure is 0.1MPa-3MPa, and the mass space velocity is 0.5h -1 -5h -1 , the volume ratio of hydrogen to hydrocarbon is 100-1600.

[0024] According to the present invention, bridged tetrahydrodicyclopentadiene and a reaction solvent are uniformly premixed in a feed tank. The mixture then flows from the upper end into a pretreatment reactor containing an adsorbent at room temperature and pressure. After impurities are removed, the mixture flows out from the lower end and is then pumped to the upper end of a fixed-bed reactor where it passes through a hydrogenation protective agent, an inert material, and an isomerization catalyst reaction bed along with hydrogen. The reaction product flows out from the lower end of the fixed bed. Samples are collected and analyzed by gas chromatography, and the reactant conversion and product selectivity are calculated using the area normalization method.

[0025] The specific embodiments of the present invention are further described below with reference to the examples.

[0026] In the following examples, bridged tetrahydrodicyclopentadiene was purchased from Beijing Yinuokai Technology Co., Ltd.

[0027] In the following examples, quartz sand was filled between the hydrogenation section and the isomerization section as an inert material.

[0028] Examples 1 to 3 (Influence of pretreatment methods)

[0029] In the pretreatment reactor, a methylcyclohexane solution containing 50 wt% of bridged tetrahydrodicyclopentadiene was used as the raw material and flowed through the pretreatment reactor equipped with different adsorbents at room temperature and pressure with a mass space velocity of 0.5 h -1 . After pretreatment, it is pumped into the fixed bed reactor. In the fixed bed reactor, the methylcyclohexane solution containing 50wt% of bridged tetrahydrodicyclopentadiene after different pretreatment methods is used as the raw material; 20wt% Ni / SiO2 is used as the hydrogenation catalyst, and the reaction temperature of the hydrogenation section is 150°C; 0.3wt% Pt / HY is used as the isomerization catalyst, and the reaction temperature of the isomerization section is 150°C. The entire fixed bed reaction pressure is 0.5MPa of hydrogen, and the mass space velocity is 2h -1 The volume ratio of hydrogen to hydrocarbon was 1000. After 200 hours of reaction, samples were taken for analysis to investigate the effect of pretreatment on catalyst activity. The results are shown in Table 1.

[0030] Table 1

[0031]

[0032] Examples 4 to 6 (Effect of Hydrogenation Protectant)

[0033] In the pretreatment reactor, a methylcyclohexane solution containing 50 wt% of bridged tetrahydrodicyclopentadiene is used as raw material, which is pre-mixed uniformly and then pre-treated with NaY to remove impurities.

[0034] In the fixed bed reactor, 0.3 wt% Pt / HY was used as the isomerization catalyst, the reaction temperature of the isomerization section was 150°C, the composition of the hydrogenation protective agent and the temperature of the hydrogenation section were shown in Table 1, the reaction pressure was 0.5 MPa hydrogen, and the mass space velocity was 2 h -1 The volume ratio of hydrogen to hydrocarbon was 1000. After 200 hours of reaction, samples were taken for analysis to investigate the effect of the hydrogenation protectant on the catalyst activity. The results are shown in Table 2.

[0035] Table 2

[0036]

[0037]

[0038] Examples 7 to 10 (Influence of Isomerization Reaction Temperature)

[0039] The raw material is a methylcyclohexane solution containing 50 wt% of bridged tetrahydrodicyclopentadiene, which is pre-mixed and then pretreated with NaY to remove impurities; 20 wt% Ni / SiO2 is used as a hydrogenation protective agent, and the hydrogenation temperature is 150 ° C; 0.3 wt% Pt / HY is used as an isomerization catalyst, the entire fixed bed reaction pressure is 0.5 MPa of hydrogen, and the mass space velocity is 1 h -1 The volume ratio of hydrogen to hydrocarbon was 1000. After 20 hours of reaction, samples were taken for analysis to investigate the effect of the isomerization reaction temperature. The results are shown in Table 3.

[0040] Table 3

[0041]

[0042] Examples 11 to 14 (Influence of Reaction Pressure)

[0043] The raw material is a methylcyclohexane solution containing 50 wt% of bridged tetrahydrodicyclopentadiene, which is pre-mixed and then pretreated with NaY to remove impurities; 20 wt% Ni / SiO2 is used as a hydrogenation protective agent, and the hydrogenation temperature is 150 ° C; 0.3 wt% Pt / HY is used as an isomerization catalyst, the isomerization reaction temperature is 150 ° C, and the mass space velocity is 1 h -1The volume ratio of hydrogen to hydrocarbon was 1000. After 20 hours of reaction, samples were taken for analysis to investigate the effect of the system's hydrogen pressure. The results are shown in Table 4.

[0044] Table 4

[0045]

[0046] Examples 15 to 18 (Influence of Reaction Space Velocity)

[0047] A methylcyclohexane solution containing 50 wt% of end-tetrahydrodicyclopentadiene was used as the raw material. After premixing and then pretreatment with NaY to remove impurities, a 20 wt% Ni / SiO2 hydrogenation protective agent was used, and the hydrogenation temperature was 150°C. A 0.3 wt% Pt / HY isomerization catalyst was used, and the isomerization temperature was 150°C. The fixed-bed reaction pressure was 0.5 MPa of hydrogen, and the hydrogen-to-hydrocarbon volume ratio was 1000. Samples were collected and analyzed after 20 hours of reaction to examine the effect of the reaction space velocity. The results are shown in Table 5.

[0048] Table 5

[0049]

[0050] Examples 19-21 (Influence of Hydrogen-Hydrocarbon Volume Ratio)

[0051] The raw material is a methylcyclohexane solution containing 50 wt% of bridged tetrahydrodicyclopentadiene, which is pre-mixed and then pretreated with NaY to remove impurities; 20 wt% Ni / SiO2 is used as a hydrogenation protective agent, and the temperature of the hydrogenation section is 150 ° C; 0.3 wt% Pt / HY is used as an isomerization catalyst, the reaction temperature of the isomerization section is 150 ° C, the entire fixed bed reaction pressure is 0.5 MPa of hydrogen, and the mass space velocity is 1 h -1 After 20 hours of reaction, samples were taken for analysis to investigate the effect of the hydrogen-to-hydrocarbon volume ratio. The results are shown in Table 6.

[0052] Table 6

[0053]

[0054] Examples 22 to 25 (Influence of Reaction Solvent and Raw Material Mass Concentration)

[0055] The raw materials are bridged tetrahydrodicyclopentadiene solutions with different mass concentrations, which are pre-mixed and then pretreated with NaY to remove impurities. 20wt% Ni / SiO2 is used as a hydrogenation protective agent, and the temperature of the hydrogenation section is 150°C. 0.3wt% Pt / HY is used as an isomerization catalyst, the reaction temperature of the isomerization section is 150°C, the entire fixed-bed reaction pressure is 0.5MPa hydrogen, and the mass space velocity is 1h -1The volume ratio of hydrogen to hydrocarbon was 1000. After 20 hours of reaction, samples were taken for analysis to investigate the effects of different reaction solvents and raw material concentrations. The results are shown in Table 7.

[0056] Table 7

[0057]

[0058]

[0059] Example 29 (System Stability Investigation)

[0060] When the operation cycle of Example 1 (after NaY pretreatment) was further extended to 2000 h, it was found that the endo-THDCPD conversion rate slowly decreased to 86%, the exo-THDCPD selectivity slowly increased to 94%, the adamantane selectivity slowly decreased to 0.6%, and the ring-opening by-product selectivity slowly decreased to 5.4%, indicating that the system has excellent stability and has prospects for industrial application.

Claims

1. A method for continuously preparing exo-tetrahydrodicyclopentadiene, comprising: The bridged tetrahydrodicyclopentadiene and the reaction solvent are passed into a pretreatment reactor equipped with an adsorbent for pretreatment, and the effluent is passed into a fixed bed reactor for hydrogenation isomerization reaction to obtain the exo-tetrahydrodicyclopentadiene; In the fixed bed reactor, the upper section is equipped with a hydrogenation protective agent, the middle section is equipped with an inert material, and the lower section is equipped with an isomerization catalyst, wherein the adsorbent is selected from activated clay and NaY molecular sieve, the hydrogenation protective agent is a supported metal hydrogenation catalyst, wherein the active metal is selected from one or more of Pd, Pt, Ru, Rh, and Ni, the carrier is selected from Al2O3, SiO2, ZrO2, TiO2, CeO2, and activated carbon, and the isomerization catalyst is a molecular sieve-supported metal catalyst, wherein the active metal is selected from Pd and Pt, and the molecular sieve is selected from HY, USY, and REHY.

2. The method according to claim 1, wherein The reaction solvent is a hydrocarbon with a boiling point of 40°C-200°C.

3. The method according to claim 1, wherein The reaction solvent is C6-C10 hydrocarbon.

4. The method according to claim 1, wherein The reaction solvent is cyclohexane or methylcyclohexane.

5. The method according to claim 1, wherein After the bridged tetrahydrodicyclopentadiene is mixed with the reaction solvent, the mass concentration of the bridged tetrahydrodicyclopentadiene is 10%-80%.

6. The method according to claim 1, wherein After the bridged tetrahydrodicyclopentadiene is mixed with the reaction solvent, the mass concentration of the bridged tetrahydrodicyclopentadiene is 30%-60%.

7. The method according to claim 1, wherein The pretreatment temperature is room temperature - 60 ° C, the pretreatment pressure is 0.1-0.5 MPa, and the adsorbent treatment space velocity is 0.1-5.0h -1 .

8. The method according to claim 1, wherein The hydrogenation protective agent is Ni / SiO2 catalyst.

9. The method according to claim 1, wherein The isomerization catalyst is a Pt / HY catalyst.

10. The method according to claim 1, wherein In the fixed bed reactor, the upper section hydrogenation reaction temperature is 100°C-200°C, and the lower section isomerization reaction temperature is 100°C-180°C.

11. The method according to claim 1, wherein In the fixed bed reactor, the upper section hydrogenation reaction temperature is 130°C-170°C, and the lower section isomerization reaction temperature is 130°C-170°C.

12. The method according to claim 1, wherein In the fixed bed reactor, the system reaction pressure is 0.1MPa-3MPa, and the mass space velocity is 0.5h -1 -5h -1 , the volume ratio of hydrogen to hydrocarbon is 100-1600.

13. The method according to claim 1, wherein: In the fixed bed reactor, the system reaction pressure is 0.5MPa-1.0MPa, and the mass space velocity is 0.5h -1 -2h -1 , the volume ratio of hydrogen to hydrocarbon is 600-1200.

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