Preparation method and system of high-purity dicyclopentadiene

Abstract

The invention discloses a preparation method and system of high-purity dicyclopentadiene, and belongs to the technical field of chemical engineering. The method comprises the following steps: sequentially carrying out pre-dimerization, first rectification, depolymerization, dimerization and second rectification on a cracked C5 fraction to obtain high-purity dicyclopentadiene, in the step of dimerization, the reaction temperature of dimerization is determined according to the content of isoprene and cyclopentadiene in the cracked C5 fraction according to the following formula 1, in the formula 1, S is the dimerization selectivity of cyclopentadiene, and the set value is 0.80 or above; iP is the mass content of isoprene in the cracked C5 fraction; cPD is the mass content of cyclopentadiene in the cracked C5 fraction; t is the reaction temperature of dimerization, and the unit is Kelvin. The method provided by the invention can improve the purity of the dicyclopentadiene product.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method and system of high-purity dicyclopentadiene, and belongs to the technical field of chemical industry. BACKGROUND

[0002] In the ethylene production by petroleum cracking, the carbon five fraction accounts for about 15%, and the carbon five fraction is complex in composition, in which the most valuable are dicyclopentadiene and isoprene, accounting for about 40-60wt%. Due to their unique molecular structure, they are extremely active in chemical properties, and thus can synthesize many important high-value-added products. The separation and utilization of cracked carbon five fraction is not only a key link for the rational development of petroleum resources, but also one of the effective means to reduce the cost of petrochemical production. Generally, the boiling points of dicyclopentadiene and isoprene are similar, and they are relatively easy to self-polymerize or mutual polymerize to form dimers, so high-purity dicyclopentadiene cannot be separated from the carbon five fraction by simple distillation process.

[0003] CN1160035A and CN1160033A respectively disclose a process for separating and purifying dicyclopentadiene by pre-thermal dimerization. The process first carries out thermal dimerization of dicyclopentadiene to convert it into dicyclopentadiene. Subsequently, isoprene and newly formed dicyclopentadiene are separated by distillation step. In some cases, in order to further improve the purity, a distillation step for removing light components is added before thermal dimerization, and the purpose is to remove carbon four components and alkyne light components in the raw material. However, in the process of thermal dimerization of dicyclopentadiene, self-polymerization or mutual polymerization may occur between isoprene and dicyclopentadiene.

[0004] CN101100412A discloses an improved carbon five fraction separation technology, which uses post-thermal dimerization to purify dicyclopentadiene. This method first separates isoprene from the carbon five fraction by distillation, and then carries out thermal dimerization of dicyclopentadiene to reduce the formation of dimers between isoprene and dicyclopentadiene. The post-thermal dimerization method solves the problems existing in the pre-thermal dimerization method to some extent, but the main problem is that, in the process of separating isoprene, it is difficult to separate isoprene in a single distillation because dicyclopentadiene has not been converted into dicyclopentadiene, and the distillate at the top of the distillation column may mix with dicyclopentadiene. More importantly, in the column bottom and stripping section of the distillation column, due to the high concentration of dicyclopentadiene and temperature conditions, the co-thermal dimerization reaction between isoprene and dicyclopentadiene is still easy to occur, resulting in the formation of a certain amount of dimers of isoprene and dicyclopentadiene in the system.

[0005] US3510405A discloses a process for separating high purity isoprene from C5 fraction, including the following steps: C5 fraction obtained by hydrocarbon steam cracking or other high temperature cracking method is subjected to thermal dimerization reaction and cyclodiene is separated therefrom; first extractive distillation is carried out in the presence of polymerization inhibitor with DMF as solvent, the solvent is recycled by stripping column; the material is subjected to rectification by a heavy component removal rectification column to separate heavy components containing cyclodiene; second extractive distillation is carried out in the presence of polymerization inhibitor with DMF as solvent, the solvent is recycled by stripping column; high purity isoprene product is obtained from the column bottom after rectification by a light component removal column.

[0006] CN1412165A discloses a separation method for cracking C5 fraction, the main feature of which is that after thermal dimerization and rectification separation of dicyclopentadiene, the C5 material is subjected to selective catalytic hydrogenation process to remove acetylenes before extractive distillation, thereby eliminating the second extractive distillation in the traditional isoprene process.

[0007] CN1253130A and CN1490286A disclose a method in which cyclodiene is dimerized into dicyclopentadiene in a reactive rectification column at the same time as separating the overhead material rich in isoprene. However, the residence time of the material in the column is difficult to control, and thus the conversion rate of cyclodiene cannot be controlled, so the concentration of cyclodiene in the overhead is generally high. In addition, the type and amount of polymerization inhibitor directly affect the operation of the reactive rectification column, so the column is not easy to operate. In view of the current research on the dimerization reaction mechanism and polymerization inhibition mechanism of diene, it is more difficult to complete the engineering design of this method, and there is currently no report on the engineering of this method.

[0008] CN101665400A proposes a C5 fraction separation method for separating isoprene twice in view of the defects of the post-thermal dimerization process, which sets a rectification column before the thermal dimerization reactor of the traditional pre-thermal dimerization process, and separates and extracts isoprene twice before and after the thermal dimerization reaction. This method better solves the problem of cyclodiene entrainment in the overhead of the isoprene rectification separation column in the post-thermal dimerization process. However, the co-thermal dimerization reaction of isoprene and cyclodiene still inevitably occurs in the column bottom and stripping section of the first isoprene rectification separation column, and in this respect it almost repeats the post-thermal dimerization process.

[0009] In summary, the separation of the cracked C5 fraction mainly utilizes the characteristic that cyclopentadiene (CPD) is easy to self-polymerize to form dicyclopentadiene (DCPD). The CPD in the cracked C5 fraction is converted into DCPD through a thermal dimerization reaction, and then the DCPD is separated from other diene components through a separation process. However, due to the complexity of the cracked C5 fraction, which contains more than 20 components, the thermal dimerization reaction process is extremely complex. In addition to the self-dimerization reaction of CPD, the self-dimerization reaction of isoprene (IP) and the co-dimerization reaction between dienes may also occur. Although a large number of studies have focused on the thermal dimerization reaction of the cracked C5 fraction, the research data on the reaction involving dienes such as isoprene are relatively less. In addition, the experimental conditions of the existing researches are different from the operating conditions of the main cracked C5 fraction separation devices in the industry, resulting in an inaccurate description of the thermal dimerization reaction law. In addition, the concentration ranges of isoprene and cyclopentadiene in cracked C5 fractions from different sources are different, which directly affects the dimerization reaction selectivity of cyclopentadiene and causes great challenges to the control of the purity of the cyclopentadiene product. SUMMARY

[0010] To solve the above technical problems, the purpose of the present application is to provide a preparation method and system of high-purity dicyclopentadiene. The present application can improve the purity of dicyclopentadiene product.

[0011] To achieve the above-mentioned purpose, the first aspect of the present application provides a preparation method of high-purity dicyclopentadiene, comprising the following steps: making a cracked C5 fraction sequentially undergo pre-dimerization, first rectification, depolymerization, dimerization and second rectification to obtain the high-purity dicyclopentadiene.

[0012] In the step of dimerization, the reaction temperature of dimerization is determined according to the content of isoprene (IP) and cyclopentadiene (CPD) in the cracked C5 fraction according to the following formula 1,

[0013] Formula 1:

[0014] wherein S is the dimerization selectivity of cyclopentadiene, and the set value is 0.80 or more; IP is the mass content of isoprene in the cracked C5 fraction; CPD is the mass content of cyclopentadiene in the cracked C5 fraction; and T is the reaction temperature of dimerization, in units of Kelvin (K).

[0015] According to the specific embodiments of the present application, preferably, the preparation method of high-purity dicyclopentadiene comprises the following steps:

[0016] (1) making the cracked C5 fraction enter a pre-dimerization reactor to undergo pre-dimerization to obtain a pre-dimerization product;

[0017] (2) feeding the pre-dimerization product into a first rectifying column to perform a first rectification, and obtaining a first rectification product from a column bottom of the first rectifying column;

[0018] (3) feeding the first rectification product and a carrier gas into a first cracking reactor to perform a depolymerization, and obtaining a first depolymerization product;

[0019] (4) feeding the first depolymerization product into a first dimerization reactor to perform a dimerization, and determining a reaction temperature of the dimerization according to a content of isoprene (IP) and cyclopentadiene (CPD) in the cracked C5 fraction according to the Formula 1, and obtaining a first dimerization product;

[0020] (5) feeding the first dimerization product into a second rectifying column to perform a second rectification, and obtaining the high-purity dicyclopentadiene from a column bottom of the second rectifying column.

[0021] According to the specific embodiment of the present application, preferably, in the step (1), the reaction temperature of the pre-dimerization is 40-60℃, the reaction pressure is 0.5-2.5Mpa, and the residence time of the cracked C5 fraction in the pre-dimerization reactor is 35-180min. More preferably, the pre-dimerization reactor is operated in full column mode, and the feed is from the bottom and the discharge is from the top of the pre-dimerization reactor.

[0022] According to the specific embodiment of the present application, preferably, in the step (2), the column bottom temperature of the first rectifying column is 45-85℃, the column top temperature is 30-50℃, the column top pressure is 0.03-0.3Mpa, and the reflux ratio is 2-15.

[0023] According to the specific embodiment of the present application, preferably, in the step (3), the reaction temperature of the depolymerization is 280-380℃, the reaction pressure is 0.02-0.05Mpa, and the residence time of the first rectification product and the carrier gas in the first cracking reactor is 1-15s. More preferably, the first rectification product is heated to 120-170℃, and then mixed with the carrier gas to enter the first cracking reactor. More preferably, the carrier gas is deoxygenated to have an oxygen content of less than 1ppm, and then heated to 280-380℃, and then mixed with the first rectification product to enter the first cracking reactor. More preferably, the ratio of the feed mass of the carrier gas to the feed mass of the first rectification product in the first cracking reactor is 1.5 or more.

[0024] According to the specific embodiment of the present application, preferably, step (3) further comprises: subjecting the product of the first cracking reactor to flash evaporation to separate the carrier gas, to obtain the first depolymerization product. More preferably, the flash evaporation is performed at a pressure of 0.01-0.3 MPa and a temperature of 15-55°C. Further preferably, the product of the first cracking reactor is first subjected to heat exchange to reach a temperature of 45-65°C, and then subjected to the flash evaporation.

[0025] According to the specific embodiment of the present application, preferably, in step (4), the dimerization is performed at a temperature of 25-85°C and a pressure of 0.1-3 MPa, and the residence time of the first depolymerization product in the first dimerization reactor is 15-180 min. More preferably, the first dimerization reactor is operated in full tank mode, with the feed being introduced from the bottom and the product being discharged from the top.

[0026] According to the specific embodiment of the present application, preferably, in step (5), the second rectification column has a column bottom temperature of 40-85°C, a column top temperature of 30-50°C, a column top pressure of 0.1-0.3 MPa, and a reflux ratio of 2-15.

[0027] According to the specific embodiment of the present application, preferably, the method for preparing high-purity dicyclopentadiene further comprises the following steps:

[0028] For a cracking C5 fraction having a mass content ratio of isoprene to cyclopentadiene of 1 or less, the set value of S in formula 1 is 0.95 or more, and after the steps (1) to (5) are performed, the high-purity dicyclopentadiene is obtained.

[0029] For a cracking C5 fraction having a mass content ratio of isoprene to cyclopentadiene of more than 1, the set value of S in formula 1 is 0.80 to less than 0.95, and after the steps (1) to (5) are performed, the product of step (5) is subjected to two-stage depolymerization-dimerization-rectification to obtain the high-purity dicyclopentadiene.

[0030] According to the specific embodiment of the present application, preferably, the two-stage depolymerization-dimerization-rectification comprises:

[0031] (6) subjecting the product of step (5) and the carrier gas to depolymerization in a second cracking reactor to obtain a second depolymerization product;

[0032] (7) subjecting the second depolymerization product to dimerization in a second dimerization reactor, and determining the dimerization temperature according to the content of isoprene (IP’) and cyclopentadiene (CPD’) in the second depolymerization product according to formula 3, to obtain a second dimerization product,

[0033] Formula 3:

[0034] wherein S' is the dimerization selectivity of the cyclopentadiene in step (7), and is set to be 0.95 or more; IP' is the mass content of isoprene in the second depolymerization product; CPD' is the mass content of cyclopentadiene in the second depolymerization product; and T' is the reaction temperature of the dimerization in step (7), in Kelvin;

[0035] (8) subjecting the second dimerization product to a third rectification in a third rectification column, and obtaining the high-purity dicyclopentadiene from the column bottom of the third rectification column.

[0036] According to the specific embodiment of the present application, preferably, in step (6), the reaction temperature of the depolymerization is 280-380°C, the reaction pressure is 0.02-0.05 MPa, and the residence time of the product of step (5) and the carrier gas in the second cracking reactor is 1-15 s. More preferably, the product of step (5) is mixed with the carrier gas after being heated to 120-170°C, and then enters the second cracking reactor. More preferably, the carrier gas is mixed with the product of step (5) after being deoxygenated to have an oxygen content of less than 1 ppm, and then heated to 280-380°C, and then enters the second cracking reactor. More preferably, the ratio of the mass of the carrier gas to the mass of the product of step (5) is 1.5 or more.

[0037] According to the specific embodiment of the present application, preferably, step (6) further comprises: subjecting the product of the second cracking reactor to flash evaporation to separate the carrier gas, and obtaining the second depolymerization product. More preferably, the flash evaporation is performed at a pressure of 0.01-0.3 MPa and a temperature of 15-55°C. Further preferably, the product of the second cracking reactor is first heated to 45-65°C, and then subjected to the flash evaporation.

[0038] According to the specific embodiment of the present application, preferably, in step (7), the reaction temperature of the dimerization is 25-85°C, the reaction pressure is 0.1-3 MPa, and the residence time of the second depolymerization product in the second dimerization reactor is 15-180 min. More preferably, the second dimerization reactor is operated in full-column mode, and the bottom of the second dimerization reactor is used as the inlet and the top of the second dimerization reactor is used as the outlet.

[0039] According to the specific embodiment of the present application, preferably, in step (8), the column bottom temperature of the third rectification column is 40-85°C, the column top temperature is 30-50°C, the column top pressure is 0.1-0.3 MPa, and the reflux ratio is 2-15.

[0040] The second aspect of the present application provides a system for preparing high-purity dicyclopentadiene, which is used to implement the method for preparing high-purity dicyclopentadiene described above, and comprises a pre-dimerization unit, a first rectification unit, a first depolymerization unit, a first dimerization unit and a second rectification unit connected in sequence.

[0041] According to the specific embodiment of the present application, preferably, the pre-dimerization unit comprises a pre-dimerization reactor, which is provided with a feed inlet at the bottom and a discharge outlet at the top.

[0042] According to the specific embodiment of the present application, preferably, the first rectification unit comprises a first rectification column, which is provided with an inlet, a first light component outlet at the top and a first rectification product outlet at the bottom.

[0043] According to the specific embodiment of the present application, preferably, the first depolymerization unit comprises a first cracking reactor, which is provided with a feed inlet at the top and a discharge outlet at the bottom, and the feed inlet of the first cracking reactor is connected to the first rectification product outlet of the first rectification column and a first carrier gas conveying pipeline. More preferably, the first depolymerization unit further comprises a first heat exchanger, and the feed inlet of the first cracking reactor is connected to the first rectification product outlet of the first rectification column through the first heat exchanger. More preferably, the first carrier gas conveying pipeline is connected to a second heat exchanger and a first deoxygenation rectification column in sequence, so as to make the oxygen content of the carrier gas less than 1 ppm after deoxygenation and then heat-exchanged to 280-380℃. More preferably, a first flow controller is further arranged between the second heat exchanger and the first deoxygenation rectification column, so as to control the flow of the carrier gas and make the ratio of the feed mass of the carrier gas to the feed mass of the first rectification product in the first cracking reactor be greater than 1.5.

[0044] According to the specific embodiment of the present application, preferably, the first depolymerization unit further comprises a first flash tank, which is provided with an inlet, a carrier gas outlet and a first depolymerization product outlet, and the inlet of the first flash tank is connected to the discharge outlet of the first cracking reactor. More preferably, the first depolymerization unit further comprises a third heat exchanger, and the inlet of the first flash tank is connected to the discharge outlet of the first cracking reactor through the third heat exchanger.

[0045] According to the specific embodiment of the present application, preferably, the first dimerization unit comprises a first dimerization reactor, which is provided with a feed inlet at the bottom and a discharge outlet at the top.

[0046] According to the specific embodiment of the present application, preferably, the second rectification unit comprises a second rectification column, which is provided with an inlet, and the top of the second rectification column is provided with a second light component outlet, and the column still is provided with a second rectification product outlet.

[0047] According to the specific embodiment of the present application, preferably, the high-purity dicyclopentadiene preparation system further comprises a two-stage depolymerization-dimerization-rectification unit, which comprises a second depolymerization unit, a second dimerization unit and a third rectification unit connected in sequence, and the two-stage depolymerization-dimerization-rectification unit is connected to the second rectification unit for further depolymerization, dimerization and rectification of the product of the second rectification unit to obtain the high-purity dicyclopentadiene.

[0048] The present application has at least the following beneficial effects:

[0049] The present application constructs a dimerization reaction selectivity model based on a dimerization reaction kinetics equation, which can determine the reaction temperature of dimerization according to the content of isoprene and cyclopentadiene in the cracked C5 fraction, thereby improving the selectivity of cyclopentadiene dimerization reaction, and cooperating with other steps in the method of the present application, the purity of dicyclopentadiene product can be significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 The structure diagram of the high-purity dicyclopentadiene preparation system in some specific embodiments of the present application.

[0051] Figure 2 The structure diagram of the high-purity dicyclopentadiene preparation system in some specific embodiments of the present application.

[0052] BRIEF DESCRIPTION OF DRAWINGS:

[0053] 1- pre-dimerization reactor; 2- first rectification column; 3- first cracking reactor; 4- first carrier gas delivery pipeline; 5- first heat exchanger; 6- second heat exchanger; 7- first deoxygenation refining column; 8- first flow controller; 9- first flash tank; 10- third heat exchanger; 11- first dimerization reactor; 12- second rectification column; 13- second cracking reactor; 14- second carrier gas delivery pipeline; 15- fourth heat exchanger; 16- fifth heat exchanger; 17- second deoxygenation refining column; 18- second flow controller; 19- second flash tank; 20- sixth heat exchanger; 21- second dimerization reactor; 22- third rectification column. DETAILED DESCRIPTION

[0054] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the present application will be described in detail below, but it cannot be understood as limiting the scope of the present application.

[0055] It should be noted that unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those of ordinary skill in the art to which the application pertains.

[0056] The various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or prepared by existing methods, unless otherwise specified.

[0057] It should be understood that the terms "comprise", "include" and / or "contain" used herein specify the presence of stated features, integers, steps, components or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, components or combinations thereof.

[0058] The endpoints of the ranges and any values disclosed in the present application are not limited to the precise values stated. The ranges or values should be construed as having a range around the values disclosed. For numerical ranges, the endpoints of the ranges are included in the ranges, the endpoints of the ranges and individual points are combinable with each other to form new numerical ranges, which should be considered as specifically disclosed in the present application.

[0059] In the description of the present application, it should be noted that the terms "first", "second" and the like are used only for the purpose of description and should not be understood as indicating or implying relative importance.

[0060] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "provided with", "sleeved / connected", "connected" and the like should be understood broadly, for example, "connected" can be fixedly connected, or detachably connected, or integrally connected, can be mechanically connected, or electrically connected, can be directly connected, or indirectly connected through an intermediate medium, can be internal communication of two elements, and the specific meaning of the above terms in the present application can be understood according to the specific circumstances by those skilled in the art.

[0061] According to the specific embodiment of the first aspect of the present application, the present application provides a preparation method of high-purity dicyclopentadiene, comprising the following steps: sequentially pre-dimerizing, first distilling, depolymerizing, dimerizing and second distilling the cracked C5 fraction to obtain the high-purity dicyclopentadiene;

[0062] In the step of dimerization, the reaction temperature of dimerization is determined according to the content of isoprene (IP) and cyclopentadiene (CPD) in the cracked C5 fraction according to the following formula 1,

[0063] Formula 1:

[0064] wherein S is the dimerization selectivity of cyclopentadiene, and is set to be 0.80 or more; IP is the mass content of isoprene in the cracking C5 fraction; CPD is the mass content of cyclopentadiene in the cracking C5 fraction; and T is the reaction temperature of dimerization, in units of Kelvin (K).

[0065] In the present application, it can be understood that the cracking C5 fraction is a petroleum cracking C5 fraction, which is one of the products of petroleum cracking for ethylene.

[0066] The present application conducts a kinetic study on the dimerization reaction accompanied by the participation of dienes such as isoprene (IP). By using the kinetic characteristics of the dimerization reaction of isoprene and cyclopentadiene, and based on the macro-kinetic equation of the thermal dimerization reaction of isoprene and cyclopentadiene, a cyclopentadiene dimerization reaction selectivity model is constructed through the Arrhenius formula. The reaction temperature of dimerization can be determined according to the contents of isoprene and cyclopentadiene in different cracking C5 fractions (specifically C 异戊二烯 / C 环戊二烯 mass content ratio, i.e. ), so as to realize high-selectivity dimerization of cyclopentadiene, efficient separation of cyclopentadiene and isoprene, and thus significantly improve the purity of dicyclopentadiene product.

[0067] Specifically, the present application explores the self-polymerization or interpolymerization of CPD and IP in the cracking C5 fraction. By using the reaction rate constants of the self-dimerization reaction of CPD, the self-dimerization reaction of IP, and the dimerization reaction of CPD and IP, a formula 2 is constructed,

[0068] Formula 2:

[0069] wherein S is the dimerization selectivity of cyclopentadiene; A1 is the exponential pre-factor of the self-dimerization reaction of CPD; A2 is the exponential pre-factor of the self-dimerization reaction of IP; A3 is the exponential pre-factor of the dimerization reaction of CPD and IP; E1 is the activation energy of the self-dimerization reaction of CPD, in units of J / mol; E2 is the activation energy of the self-dimerization reaction of IP, in units of J / mol; E3 is the activation energy of the dimerization reaction of CPD and IP, in units of J / mol; R is the molar gas constant, and is taken as 8.314 J / (mol·K); exp is the exponential function e x wherein e is the natural constant (i.e. Euler number), and is taken as 2.71828; IP is the mass content of isoprene in the cracking C5 fraction; CPD is the mass content of cyclopentadiene in the cracking C5 fraction; and T is the reaction temperature of dimerization, in units of Kelvin (K).

[0070] Through the Arrhenius formula, the exponential pre-exponential factor and activation energy of the self-dimerization reaction of CPD, the self-dimerization reaction of IP and the dimerization reaction of CPD and IP can be calculated, thereby obtaining the formula 1, i.e. the CPD dimerization reaction selectivity model of the application.

[0071] In some embodiments, the method for preparing high-purity dicyclopentadiene comprises the following steps:

[0072] (1) introducing the cracked C5 fraction into a pre-dimerization reactor for pre-dimerization to obtain a pre-dimerization product;

[0073] (2) introducing the pre-dimerization product into a first rectifying column for first rectification, and obtaining a first rectification product from the column bottom of the first rectifying column;

[0074] (3) introducing the first rectification product and a carrier gas into a first depolymerization reactor for depolymerization to obtain a first depolymerization product;

[0075] (4) introducing the first depolymerization product into a first dimerization reactor for dimerization, and determining the reaction temperature of dimerization according to the formula 1 based on the content of isoprene (IP) and cyclopentadiene (CPD) in the cracked C5 fraction to obtain a first dimerization product;

[0076] (5) introducing the first dimerization product into a second rectifying column for second rectification, and obtaining the high-purity dicyclopentadiene from the column bottom of the second rectifying column.

[0077] In some embodiments, in step (1), the reaction temperature of pre-dimerization is 40-60°C, the reaction pressure is 0.5-2.5 MPa, and the residence time of the cracked C5 fraction in the pre-dimerization reactor is 35-180 min. Preferably, the pre-dimerization reactor is operated in full column mode, with the feed introduced from the bottom and the product discharged from the top. By operating the pre-dimerization reactor in full column mode, the self-polymerization of butadiene and the dimerization of butadiene with cyclopentadiene can be inhibited, and the influence of tetrahydroindenyl and vinyl cyclohexene on the purity of dicyclopentadiene product can be reduced.

[0078] In some embodiments, in step (2), the column bottom temperature of the first rectifying column is 45-85°C, the column top temperature is 30-50°C, the column top pressure is 0.03-0.3 MPa, and the reflux ratio is 2-15. In the first rectifying column, the light components that are not dimerized, referred to as first light components, can be removed from the column top, and the first rectification product from the column bottom is mainly dicyclopentadiene, with the by-products mainly being isoprene dimers and cyclopentadiene and isoprene co-dimers, and possibly containing a small amount of butadiene dimers and dimers with cyclopentadiene, etc.

[0079] In some embodiments, in step (3), the reaction temperature of the depolymerization is 280-380°C, the reaction pressure is 0.02-0.05 MPa, and the residence time of the first rectification product and the carrier gas in the first cracking reactor is 1-15 s. By controlling the conditions of the depolymerization within the above ranges, the first rectification product is facilitated to be completely depolymerized into monomers in the first cracking reactor. Preferably, the first rectification product is mixed with the carrier gas after being heated to 120-170°C and then enters the first cracking reactor. The carrier gas can be, for example, nitrogen with a purity of greater than 99.9 wt%. Preferably, the carrier gas is mixed with the first rectification product after being deoxygenated to have an oxygen content of less than 1 ppm and then heated to 280-380°C and then enters the first cracking reactor. Preferably, the ratio of the feed mass of the carrier gas to the feed mass of the first rectification product in the first cracking reactor is greater than 1.5, and more preferably greater than 3.5. By controlling the ratio of the feed mass of the carrier gas to the feed mass of the first rectification product in the cracking reactor to be greater than 1.5, the volume fraction of the cyclopentadiene generated by the depolymerization in the reaction system in the cracking reactor can be controlled to be about 20% or less. By controlling the ratio of the feed mass of the carrier gas to the feed mass of the first rectification product in the cracking reactor to be greater than 3.5, the volume fraction of the cyclopentadiene generated by the depolymerization in the reaction system in the cracking reactor can be further controlled to be about 10% or less, thereby inhibiting the generation of polymers due to the excessively high concentration of cyclopentadiene.

[0080] In the present application, by sequentially performing the steps of pre-dimerization, first rectification, and depolymerization, the impurities that are not dimerized can be separated, and the purity of the dicyclopentadiene can be improved in the subsequent dimerization step.

[0081] In some embodiments, step (3) further comprises: subjecting the product of the first cracking reactor to flash evaporation to separate the carrier gas, thereby obtaining the first depolymerization product. Preferably, the flash evaporation is performed at a pressure of 0.01-0.3 MPa and a temperature of 15-55°C. More preferably, the flash evaporation is performed at a pressure of 0.02-0.05 MPa and a temperature of 20-35°C. More preferably, the product of the first cracking reactor is first heated to 45-65°C and then subjected to the flash evaporation. More preferably, the separated carrier gas from the flash evaporation is recycled.

[0082] In some embodiments, in step (4), the dimerization reaction temperature is 25-85°C, the reaction pressure is 0.1-3 MPa, and the residence time of the first depolymerization product in the first dimerization reactor is 15-180 min. Preferably, the first dimerization reactor is operated in full tank mode, with the feed being introduced from the bottom and the product being discharged from the top. In the dimerization step, by selecting the reaction temperature according to Formula 1 and further controlling the reaction temperature within the above range and controlling the reaction pressure and residence time within the above range, the reaction of cyclopentadiene dimerization and a very small amount of isoprene self-polymerization and other side reactions are facilitated, and the conversion of cyclopentadiene is improved. By operating the first dimerization reactor in full tank mode, the self-polymerization of butadiene and the dimerization of cyclopentadiene can be further inhibited, and the influence of tetrahydroindenyl and vinyl cyclohexene on the purity of dicyclopentadiene product is further reduced.

[0083] In some embodiments, in step (5), the column bottom temperature of the second rectification column is 40-85°C, the column top temperature is 30-50°C, the column top pressure is 0.1-0.3 MPa, and the reflux ratio is 2-15. In the second rectification column, light components such as isoprene and a small amount of cyclopentadiene are removed, which are referred to as second light components, and flow out from the column top; the second rectification product at the column bottom is high-purity dicyclopentadiene.

[0084] In some embodiments, the method for preparing high-purity dicyclopentadiene further comprises the following steps:

[0085] For a cracked C5 fraction with a mass content ratio of isoprene to cyclopentadiene of 1 or less, the set value of S in Formula 1 is 0.95 or more, and after the steps (1) to (5) are performed, the high-purity dicyclopentadiene is obtained;

[0086] For a cracked C5 fraction with a mass content ratio of isoprene to cyclopentadiene of more than 1, the set value of S in Formula 1 is 0.80 to less than 0.95 (preferably 0.82-0.90), and after the steps (1) to (5) are performed, the product of step (5) (i.e., the second rectification product) is subjected to a two-stage depolymerization-dimerization-rectification to obtain the high-purity dicyclopentadiene.

[0087] In some embodiments, the two-stage depolymerization-dimerization-rectification comprises:

[0088] (6) introducing the product of step (5) and a carrier gas into a second cracking reactor for depolymerization to obtain a second depolymerization product;

[0089] (7) making the second depolymerization product enter into a second dimerization reactor for dimerization, determining the reaction temperature of dimerization according to the content of isoprene (IP') and cyclopentadiene (CPD') in the second depolymerization product according to Formula 3, to obtain a second dimerization product,

[0090] Formula 3:

[0091] wherein S' is the dimerization selectivity of cyclopentadiene in step (7), and is set to be greater than or equal to 0.95; IP' is the mass content of isoprene in the second depolymerization product; CPD' is the mass content of cyclopentadiene in the second depolymerization product; and T' is the reaction temperature of dimerization in step (7), in units of Kelvin;

[0092] (8) making the second dimerization product enter into a third rectifying column for third rectification, and obtaining the high-purity dicyclopentadiene from the column bottom of the third rectifying column.

[0093] The mass content ratio of isoprene to cyclopentadiene in the cracked C5 fraction is about 0.8-1.5, which varies with different cracked C5 fractions. The present application has found that when C 异戊二烯 / C 环戊二烯 is greater than 1, it is difficult to prepare DCPD with purity greater than 95% by one-stage dimerization rectification. Therefore, for the cracked C5 fraction with C 异戊二烯 / C 环戊二烯 greater than 1, the present application adopts a two-stage depolymerization-dimerization-rectification procedure, that is, repeating steps (3)-(5), and controlling the set value of S in Formula 1 to be 0.80 to less than 0.95, and the set value of S' in Formula 3 to be greater than or equal to 0.95, so as to obtain dicyclopentadiene with purity greater than 95%. For the cracked C5 fraction with C 异戊二烯 / C 环戊二烯 less than or equal to 1, a one-stage depolymerization-dimerization-rectification procedure is adopted, and the set value of S in Formula 1 is controlled to be greater than or equal to 0.95, that is, after steps (1)-(5), dicyclopentadiene with purity greater than 95% can be obtained. The present application can be used to prepare high-purity dicyclopentadiene from different cracked C5 fractions with C 异戊二烯 / C 环戊二烯 .

[0094] In some embodiments, in step (6), the depolymerization reaction temperature is 280-380°C, the reaction pressure is 0.02-0.05 MPa, and the residence time of the product of step (5) and the carrier gas in the second cracking reactor is 1-15 s. Preferably, the product of step (5) is heated to 120-170°C, mixed with the carrier gas, and then fed into the second cracking reactor. The carrier gas can be, for example, nitrogen with a purity of greater than 99.9 wt%. Preferably, the carrier gas is deoxygenated to have an oxygen content of less than 1 ppm, heated to 280-380°C, mixed with the product of step (5), and then fed into the second cracking reactor. Preferably, the ratio of the feed mass of the carrier gas to the feed mass of the product of step (5) in the second cracking reactor is greater than 1.5, and more preferably greater than 3.5.

[0095] In some embodiments, step (6) further comprises: flashing the product of the second cracking reactor to separate the carrier gas, to obtain the second depolymerization product. Preferably, the flashing is performed at a pressure of 0.01-0.3 MPa and a temperature of 15-55°C. More preferably, the flashing is performed at a pressure of 0.02-0.05 MPa and a temperature of 20-35°C. More preferably, the product of the second cracking reactor is first heated to 45-65°C, and then subjected to the flashing. More preferably, the separated carrier gas from the flashing is recycled.

[0096] In some embodiments, in step (7), the dimerization reaction temperature is 25-85°C, the reaction pressure is 0.1-3 MPa, and the residence time of the second depolymerization product in the second dimerization reactor is 15-180 min. Preferably, in step (7), the dimerization reaction temperature is 30-60°C, the reaction pressure is 0.2-1.0 MPa, and the residence time of the second depolymerization product in the second dimerization reactor is 45-160 min. Preferably, the second dimerization reactor is operated in a full-pot mode, with the feed being introduced from the bottom and the product being discharged from the top. In step (7), by selecting the reaction temperature according to formula 3 and further controlling the reaction temperature to be within the above range and controlling the reaction pressure and the residence time to be within the above range, the dimerization of cyclopentadiene is facilitated, and the self-polymerization of isoprene and other side reactions are greatly reduced, and the conversion of cyclopentadiene is improved. By operating the second dimerization reactor in a full-pot mode, the self-polymerization of butadiene and the dimerization of cyclopentadiene are further inhibited, and the influence of tetrahydroindenyl and vinyl cyclohexene on the purity of the dicyclopentadiene product is further reduced.

[0097] In some embodiments, in step (8), the third rectification column has a column bottom temperature of 40-85°C, a column top temperature of 30-50°C, a column top pressure of 0.1-0.3 MPa, and a reflux ratio of 2-15.

[0098] According to the specific embodiments of the second aspect of the present application, the present application provides a system for preparing high-purity dicyclopentadiene, which is used to implement the above-mentioned method for preparing high-purity dicyclopentadiene, as shown in the figure, the system comprises, in sequence, a pre-dimerization unit, a first rectification unit, a first depolymerization unit, a first dimerization unit, and a second rectification unit. Figure 1

[0099] In some embodiments, the pre-dimerization unit comprises a pre-dimerization reactor 1, which is provided with a feed inlet at the bottom and a discharge outlet at the top. Preferably, the discharge outlet of the pre-dimerization reactor 1 is provided with a back pressure valve.

[0100] In some embodiments, the first rectification unit comprises a first rectification column 2, which is provided with an inlet, a first light component outlet at the top, and a first rectification product outlet at the column bottom. It can be understood that the inlet of the first rectification column 2 is connected to the discharge outlet of the pre-dimerization reactor 1.

[0101] In some embodiments, the first depolymerization unit comprises a first cracking reactor 3, which is provided with a feed inlet at the top and a discharge outlet at the bottom, and the feed inlet of the first cracking reactor 3 is connected to the first rectification product outlet of the first rectification column 2 and a first carrier gas delivery pipeline 4. Specifically, the first cracking reactor 3 is a tubular cracking reactor. Preferably, the discharge outlet of the first cracking reactor 3 is provided with a back pressure valve to facilitate control of the reaction pressure. Preferably, the first depolymerization unit further comprises a first heat exchanger 5, and the feed inlet of the first cracking reactor 3 is connected to the first rectification product outlet of the first rectification column 2 through the first heat exchanger 5. Preferably, the first carrier gas delivery pipeline 4 is connected, in sequence, to a second heat exchanger 6 and a first deoxygenation polishing column 7, so that the carrier gas is deoxygenated to have an oxygen content of less than 1 ppm and then heated to 280-380°C. Preferably, a first flow controller 8 is further provided between the second heat exchanger 6 and the first deoxygenation polishing column 7, to control the flow of the carrier gas so that the ratio of the mass of the carrier gas fed into the first cracking reactor 3 to the mass of the first rectification product is greater than 1.5 (more preferably greater than 3.5).

[0102] ​In some embodiments, the first depolymerization unit further includes a first flash tank 9, which has an inlet, a carrier gas outlet, and a first depolymerization product outlet. The inlet of the first flash tank 9 is connected to the outlet of the first pyrolysis reactor 3. Preferably, the first depolymerization unit further includes a third heat exchanger 10, and the inlet of the first flash tank 9 is connected to the outlet of the first pyrolysis reactor 3 via the third heat exchanger 10. Preferably, the carrier gas outlet of the first flash tank 9 is connected to a first deoxygenation purification column 7 for recycling the carrier gas.

[0103] In some embodiments, the first dimerization unit includes a first dimerization reactor 11, which has a feed inlet at the bottom and a discharge outlet at the top. Preferably, the discharge outlet of the first dimerization reactor 11 is equipped with a back pressure valve.

[0104] In some embodiments, the second distillation unit includes a second distillation column 12, which has an inlet, a second light component outlet at the top, and a second distillation product outlet at the bottom. It is understood that the inlet of the second distillation column 12 is connected to the outlet of the first dimerization reactor 11.

[0105] In some embodiments, such as Figure 2 As shown, the high-purity dicyclopentadiene preparation system further includes a two-stage depolymerization-dimerization-distillation unit, which includes a second depolymerization unit, a second dimerization unit, and a third distillation unit connected in sequence. The two-stage depolymerization-dimerization-distillation unit is connected to the second distillation unit and is used to further depolymerize, dimerize, and distill the product of the second distillation unit to obtain the high-purity dicyclopentadiene.

[0106] The second depolymerization unit has the same structure as the first depolymerization unit, the second dimerization unit has the same structure as the first dimerization unit, and the third distillation unit has the same structure as the second distillation unit.

[0107] Specifically, in some embodiments, the second depolymerization unit comprises a second cracking reactor 13, the top of the second cracking reactor 13 is provided with a feed inlet, the bottom is provided with a discharge outlet, the feed inlet of the second cracking reactor 13 is connected to the second rectification product outlet of the second rectification column 12 and the second carrier gas delivery pipeline 14. Specifically, the second cracking reactor 13 is a tubular cracking reactor. Preferably, the discharge outlet of the second cracking reactor 13 is provided with a back pressure valve to facilitate control of the reaction pressure. Preferably, the second depolymerization unit further comprises a fourth heat exchanger 15, the feed inlet of the second cracking reactor 13 is connected to the second rectification product outlet of the second rectification column 12 through the fourth heat exchanger 15. Preferably, the second carrier gas delivery pipeline 14 is connected to a fifth heat exchanger 16 and a second deoxygenation polishing column 17 in sequence, so that the carrier gas is deoxygenated to have an oxygen content of less than 1 ppm and then is heated to 280-380°C. Preferably, a second flow controller 18 is further arranged between the fifth heat exchanger 16 and the second deoxygenation polishing column 17, to control the flow of the carrier gas so that the ratio of the feed mass of the carrier gas in the second cracking reactor 13 to the feed mass of the product of the second rectification unit is greater than 1.5 (more preferably greater than 3.5).

[0108] In some embodiments, the second depolymerization unit further comprises a second flash tank 19, the second flash tank 19 is provided with an inlet, a carrier gas outlet and a second depolymerization product outlet, the inlet of the second flash tank 19 is connected to the discharge outlet of the second cracking reactor 13. Preferably, the second depolymerization unit further comprises a sixth heat exchanger 20, the inlet of the second flash tank 19 is connected to the discharge outlet of the second cracking reactor 13 through the sixth heat exchanger 20. Preferably, the carrier gas outlet of the second flash tank 19 is connected to the second deoxygenation polishing column 17, to recycle the carrier gas.

[0109] In some embodiments, the second dimerization unit comprises a second dimerization reactor 21, the bottom of the second dimerization reactor 21 is provided with a feed inlet, the top is provided with a discharge outlet. Preferably, the discharge outlet of the second dimerization reactor 21 is provided with a back pressure valve.

[0110] In some embodiments, the third rectification unit comprises a third rectification column 22, the third rectification column 22 is provided with an inlet, the top of the third rectification column 22 is provided with a third light component outlet, the bottom is provided with a third rectification product outlet. It can be understood that the inlet of the third rectification column 22 is connected to the discharge outlet of the second dimerization reactor 21.

[0111] The technical solutions of the present application are specifically illustrated by the following examples, but the present application is not limited to these examples, and various modifications can be made within the scope of the gist of the present application.

[0112] Example 1

[0113] This embodiment provides a system for preparing high-purity dicyclopentadiene, such as... Figure 1 As shown, it includes: a pre-dimerization unit, a first distillation unit, a first depolymerization unit, a first dimerization unit, and a second distillation unit connected in sequence.

[0114] The pre-dimerization unit includes a pre-dimerization reactor 1, which has a feed inlet at the bottom and a discharge outlet at the top. A back pressure valve is installed at the discharge outlet of the pre-dimerization reactor 1.

[0115] The first distillation unit includes a first distillation column 2, which has an inlet, a first light component outlet at the top, and a first distillation product outlet at the bottom. The inlet of the first distillation column 2 is connected to the outlet of the predimerization reactor 1.

[0116] The first depolymerization unit includes a first cracking reactor 3, which has an inlet at the top and an outlet at the bottom. The inlet of the first cracking reactor 3 is connected to the first distillation product outlet of the first distillation column 2 and the first carrier gas delivery line 4. The first cracking reactor 3 is a tubular cracking reactor. A back pressure valve is provided at the outlet of the first cracking reactor 3. The first depolymerization unit also includes a first heat exchanger 5, through which the inlet of the first cracking reactor 3 is connected to the first distillation product outlet of the first distillation column 2. The first carrier gas delivery line 4 is sequentially connected to a second heat exchanger 6 and a first deoxygenation and purification column 7. A first flow controller 8 is also provided between the second heat exchanger 6 and the first deoxygenation and purification column 7.

[0117] The first depolymerization unit further includes a first flash tank 9, which has an inlet, a carrier gas outlet, and a first depolymerization product outlet. The inlet of the first flash tank 9 is connected to the outlet of the first pyrolysis reactor 3. The first depolymerization unit also includes a third heat exchanger 10, through which the inlet of the first flash tank 9 is connected to the outlet of the first pyrolysis reactor 3. The carrier gas outlet of the first flash tank 9 is connected to the first deoxidation and purification column 7 for recycling the carrier gas.

[0118] The first dimerization unit includes a first dimerization reactor 11, which has a feed inlet at the bottom and a discharge outlet at the top. A back pressure valve is installed at the discharge outlet of the first dimerization reactor 11. The feed inlet of the first dimerization reactor 11 is connected to the first depolymerization product outlet of the first flash tank 9.

[0119] The second distillation unit includes a second distillation column 12, which has an inlet, a second light component outlet at the top, and a second distillation product outlet at the bottom, producing high-purity dicyclopentadiene. The inlet of the second distillation column 12 is connected to the outlet of the first dimerization reactor 11.

[0120] Embodiment 2

[0121] The embodiment provides a preparation system of high-purity dicyclopentadiene, as shown in the figure, which comprises a pre-dimerization unit, a first rectification unit, a first depolymerization unit, a first dimerization unit, a second rectification unit and a two-stage depolymerization-dimerization-rectification unit connected in sequence. Figure 2 The pre-dimerization unit comprises a pre-dimerization reactor 1, and the pre-dimerization reactor 1 is provided with a feed inlet at the bottom and a discharge outlet at the top. The discharge outlet of the pre-dimerization reactor 1 is provided with a back pressure valve.

[0122] The first rectification unit comprises a first rectification column 2, and the first rectification column 2 is provided with an inlet. The first rectification column 2 is provided with a first light component outlet at the top and a first rectification product outlet at the bottom. The inlet of the first rectification column 2 is connected to the discharge outlet of the pre-dimerization reactor 1.

[0123] The first depolymerization unit comprises a first cracking reactor 3, and the first cracking reactor 3 is provided with a feed inlet at the top and a discharge outlet at the bottom. The feed inlet of the first cracking reactor 3 is connected to the first rectification product outlet of the first rectification column 2 and a first carrier gas conveying pipeline 4. The first cracking reactor 3 is a tubular cracking reactor. The discharge outlet of the first cracking reactor 3 is provided with a back pressure valve. The first depolymerization unit further comprises a first heat exchanger 5, and the feed inlet of the first cracking reactor 3 is connected to the first rectification product outlet of the first rectification column 2 through the first heat exchanger 5. The first carrier gas conveying pipeline 4 is connected to a second heat exchanger 6 and a first deoxygenation rectification column 7 in sequence. A first flow controller 8 is further arranged between the second heat exchanger 6 and the first deoxygenation rectification column 7.

[0124] The first depolymerization unit further comprises a first flash tank 9, and the first flash tank 9 is provided with an inlet, a carrier gas outlet and a first depolymerization product outlet. The inlet of the first flash tank 9 is connected to the discharge outlet of the first cracking reactor 3. The first depolymerization unit further comprises a third heat exchanger 10, and the inlet of the first flash tank 9 is connected to the discharge outlet of the first cracking reactor 3 through the third heat exchanger 10. The carrier gas outlet of the first flash tank 9 is connected to the first deoxygenation rectification column 7, so as to recycle the carrier gas.

[0125] The first dimerization unit comprises a first dimerization reactor 11, and the first dimerization reactor 11 is provided with a feed inlet at the bottom and a discharge outlet at the top. The discharge outlet of the first dimerization reactor 11 is provided with a back pressure valve. The feed inlet of the first dimerization reactor 11 is connected to the first depolymerization product outlet of the first flash tank 9.

[0126] The first dimerization unit comprises a first dimerization reactor 11, and the first dimerization reactor 11 is provided with a feed inlet at the bottom and a discharge outlet at the top. The discharge outlet of the first dimerization reactor 11 is provided with a back pressure valve. The feed inlet of the first dimerization reactor 11 is connected to the first depolymerization product outlet of the first flash tank 9.

[0127] The second rectification unit comprises a second rectification column 12, which is provided with an inlet, and the top of the second rectification column 12 is provided with a second light component outlet, and the bottom is provided with a second rectification product outlet. The inlet of the second rectification column 12 is connected to the outlet of the first dimerization reactor 11.

[0128] The two-stage depolymerization-dimerization-rectification unit comprises a second depolymerization unit, a second dimerization unit and a third rectification unit connected in sequence, and the two-stage depolymerization-dimerization-rectification unit is connected to the second rectification product outlet of the second rectification unit.

[0129] The second depolymerization unit comprises a second cracking reactor 13, which is provided with an inlet at the top and an outlet at the bottom. The inlet of the second cracking reactor 13 is connected to the second rectification product outlet of the second rectification column 12 and a second carrier gas conveying pipeline 14. The second cracking reactor 13 is a tubular cracking reactor. The outlet of the second cracking reactor 13 is provided with a back pressure valve. The second depolymerization unit further comprises a fourth heat exchanger 15, and the inlet of the second cracking reactor 13 is connected to the second rectification product outlet of the second rectification column 12 through the fourth heat exchanger 15. The second carrier gas conveying pipeline 14 is connected to a fifth heat exchanger 16 and a second deoxygenation rectification column 17 in sequence. A second flow controller 18 is further arranged between the fifth heat exchanger 16 and the second deoxygenation rectification column 17.

[0130] The second depolymerization unit further comprises a second flash tank 19, which is provided with an inlet, a carrier gas outlet and a second depolymerization product outlet. The inlet of the second flash tank 19 is connected to the outlet of the second cracking reactor 13. The second depolymerization unit further comprises a sixth heat exchanger 20, and the inlet of the second flash tank 19 is connected to the outlet of the second cracking reactor 13 through the sixth heat exchanger 20. The carrier gas outlet of the second flash tank 19 is connected to the second deoxygenation rectification column 17 for recycling the carrier gas.

[0131] The second dimerization unit comprises a second dimerization reactor 21, which is provided with an inlet at the bottom and an outlet at the top. The outlet of the second dimerization reactor 21 is provided with a back pressure valve. The inlet of the second dimerization reactor 21 is connected to the second depolymerization product outlet of the second flash tank 19.

[0132] The third rectification unit comprises a third rectification column 22, which is provided with an inlet, and the top of the third rectification column 22 is provided with a third light component outlet, and the bottom is provided with a third rectification product outlet, and high-purity dicyclopentadiene is output. The inlet of the third rectification column 22 is connected to the outlet of the second dimerization reactor 21.

[0133] Examples 3-5

[0134] Embodiments 3-5 provide methods for preparing high purity dicyclopentadiene, respectively, using the system provided in Embodiment 1, the method comprising the following steps:

[0135] (1) The cracked C5 fraction is pumped into a pre-dimerization reactor 1 for pre-dimerization, the pre-dimerization reactor 1 is operated in full tank mode, the feed is from the bottom and the product is discharged from the top, to obtain a pre-dimerization product;

[0136] (2) The pre-dimerization product is discharged through a back pressure valve and then enters a first rectifying column 2 for first rectification, the first light component is obtained from the top of the first rectifying column 2, and the first rectification product is obtained from the tank;

[0137] (3) The first rectification product is heat exchanged by a first heat exchanger 5, mixed with a carrier gas, and then enters a first cracking reactor 3 for depolymerization to obtain a product of the first cracking reactor 3; wherein the carrier gas is nitrogen with a purity of more than 99.9wt%, the oxygen content is less than 1ppm after deoxidization by a first deoxidization rectification column 7, and then the carrier gas is metered by a first flow controller 8, heat exchanged by a second heat exchanger 6, and then mixed with the first rectification product; then the product of the first cracking reactor 3 is heat exchanged and condensed by a third heat exchanger 10, enters a first flash tank 9 for flash evaporation to separate the carrier gas, to obtain a first depolymerization product, and the separated carrier gas is recycled;

[0138] (4) The first depolymerization product enters a first dimerization reactor 11 for dimerization, the first dimerization reactor 11 is operated in full tank mode, the feed is from the bottom and the product is discharged from the top, the reaction temperature of dimerization is determined according to the content of isoprene and cyclopentadiene in the cracked C5 fraction according to Formula 1, to obtain a first dimerization product;

[0139] Formula 1:

[0140] Wherein, S is the dimerization selectivity of cyclopentadiene, the set value is more than 0.95; IP is the mass content of isoprene in the cracked C5 fraction; CPD is the mass content of cyclopentadiene in the cracked C5 fraction; T is the reaction temperature of dimerization, in Kelvin (K);

[0141] (5) The first dimerization product enters a second rectifying column 12 for second rectification, the second light component is obtained from the top of the second rectifying column 12, and the high purity dicyclopentadiene is obtained from the tank.

[0142] Embodiments 6-8

[0143] Embodiments 6-8 provide methods for preparing high purity dicyclopentadiene, respectively, using the system provided in Embodiment 2, the method comprising the following steps:

[0144] (1) the cracking C5 fraction is pumped into a pre-dimerization reactor 1 to perform pre-dimerization, the pre-dimerization reactor 1 is full of liquid, the feed is from the bottom and the product is from the top, and a pre-dimerization product is obtained;

[0145] (2) the pre-dimerization product is discharged through a back pressure valve and then enters a first rectifying column 2 to perform first rectification, the first light component is obtained from the top of the first rectifying column 2, and a first rectification product is obtained from the bottom of the first rectifying column 2;

[0146] (3) the first rectification product is exchanged heat through a first heat exchanger 5, mixed with a carrier gas, and then enters a first cracking reactor 3 to perform depolymerization, and a product of the first cracking reactor 3 is obtained; wherein the carrier gas is nitrogen with a purity of greater than 99.9wt%, the oxygen content is less than 1ppm after deoxidization through a first deoxidization rectification column 7, and the first rectification product is mixed after metering through a first flow controller 8 and exchanging heat through a second heat exchanger 6; then the product of the first cracking reactor 3 is exchanged heat through a third heat exchanger 10 and condensed, enters a first flash tank 9 to perform flash evaporation, separates the carrier gas, obtains a first depolymerization product, and the separated carrier gas is recycled;

[0147] (4) the first depolymerization product enters a first dimerization reactor 11 to perform dimerization, the first dimerization reactor 11 is full of liquid, the feed is from the bottom and the product is from the top, the reaction temperature of dimerization is determined according to the content of isoprene and cyclopentadiene in the cracking C5 fraction according to formula 1, and a first dimerization product is obtained;

[0148] Formula 1:

[0149] wherein S is the dimerization selectivity of cyclopentadiene, the set value is 0.82-0.90; IP is the mass content of isoprene in the cracking C5 fraction; CPD is the mass content of cyclopentadiene in the cracking C5 fraction; and T is the reaction temperature of dimerization, in units of Kelvin (K);

[0150] (5) the first dimerization product enters a second rectifying column 12 to perform second rectification, the second light component is obtained from the top of the second rectifying column 12, and a second rectification product is obtained from the bottom of the second rectifying column 12;

[0151] (6) the second rectification product enters a two-stage depolymerization-dimerization-rectification unit, exchanges heat with the carrier gas through the fourth heat exchanger 15, and enters the second cracking reactor 13 for depolymerization to obtain the product of the second cracking reactor 13; wherein the carrier gas is nitrogen with a purity of greater than 99.9wt%, the oxygen content is less than 1ppm after deoxygenation through the second deoxygenation rectification column 17, and then enters the fifth heat exchanger 16 for heat exchange after metering through the second flow controller 18, and then is mixed with the second rectification product; then the product of the second cracking reactor 13 exchanges heat through the sixth heat exchanger 20 and is condensed, enters the second flash tank 19 for flash evaporation to separate the carrier gas, to obtain the second depolymerization product, and the separated carrier gas after flash evaporation is recycled;

[0152] (7) the second depolymerization product enters the second dimerization reactor 21 for dimerization, the second dimerization reactor 21 adopts full kettle operation, the feed is from the bottom and the discharge is from the top, the reaction temperature of dimerization is determined according to the content of isoprene (IP') and cyclopentadiene (CPD') in the second depolymerization product according to formula 3, to obtain the second dimerization product,

[0153] Formula 3:

[0154] wherein S' is the dimerization selectivity of cyclopentadiene in step (7), and the set value is 0.95 or more; IP' is the mass content of isoprene in the second depolymerization product; CPD' is the mass content of cyclopentadiene in the second depolymerization product; T' is the reaction temperature of dimerization in step (7), and the unit is Kelvin;

[0155] (8) the second dimerization product enters the third rectification column 22 for third rectification, and the third light component is obtained from the top of the third rectification column 22, and the high-purity dicyclopentadiene is obtained from the kettle.

[0156] Comparative Examples 1-2

[0157] Comparative Examples 1-2 respectively provide a preparation method of high-purity dicyclopentadiene, which is carried out by using the system provided in Example 1, and the method is basically the same as that in Examples 3-5, and the difference lies in that the reaction temperature in the first dimerization reactor 11 of Comparative Example 1 is not determined according to formula 1; and Comparative Example 2 adopts C 异戊二烯 / C 环戊二烯 The cracking carbon five fraction with a cracking degree greater than 1 is used as the raw material, only one-stage depolymerization-dimerization-rectification step is carried out, and the reaction temperature in the first dimerization reactor 11 is not determined according to formula 1.

[0158] Comparative Examples 3-4

[0159] Comparative Examples 3-4 provide methods for preparing high purity dicyclopentadiene, using the system provided in Example 2, which are substantially the same as Examples 6-8, except that in Comparative Example 3, the reaction temperature in the second dimerization reactor 21 of the second stage is not determined according to Formula 3; and in Comparative Example 4, the reaction temperature in the first dimerization reactor 11 of the first stage is not determined according to Formula 1, and the reaction temperature in the second dimerization reactor 21 of the second stage is not determined according to Formula 3.

[0160] The mass ratio of isoprene to cyclopentadiene in the cracked C5 fraction used in Examples 3-8 and Comparative Examples 1-4 is shown in Table 1. The mass ratio is calculated from the mass content of isoprene and cyclopentadiene obtained by gas chromatography detection of the cracked C5 fraction. In Examples 3-5, the cracked C5 fraction used is C 异戊二烯 / C 环戊二烯 High purity dicyclopentadiene is prepared using a one-stage depolymerization-dimerization-distillation process, using a cracked C5 fraction having a mass ratio of isoprene to cyclopentadiene of less than 1 as the raw material. In Examples 6-8, the cracked C5 fraction used is C 异戊二烯 / C 环戊二烯 High purity dicyclopentadiene is prepared using a two-stage depolymerization-dimerization-distillation process, using a cracked C5 fraction having a mass ratio of isoprene to cyclopentadiene of greater than 1 as the raw material. The mass ratio of isoprene to cyclopentadiene in the second depolymerization product of Examples 6-8 and Comparative Examples 3-4 is shown in Table 2.

[0161] The operating conditions of the pre-dimerization reactor 1, the first dimerization reactor 11 of the first stage, and the second dimerization reactor 21 of the second stage in the above examples and comparative examples are shown in Table 3.

[0162] The operating conditions of the first distillation column 2, the second distillation column 12 of the first stage, and the third distillation column 22 of the second stage in the above examples and comparative examples are shown in Table 4.

[0163] The outlet temperatures of the first heat exchanger 5, the second heat exchanger 6, and the third heat exchanger 10 of the first stage, and the fourth heat exchanger 15, the fifth heat exchanger 16, and the sixth heat exchanger 20 of the second stage in the above examples and comparative examples are shown in Table 5.

[0164] The operating conditions of the first cracking reactor 3 and the first flash tank 9 of the first stage, and the second cracking reactor 13 and the second flash tank 19 of the second stage in the above examples and comparative examples are shown in Tables 6 and 7, respectively.

[0165] The conversion rate and product purity in the above examples and comparative examples are shown in Table 8. Cyclopentadiene conversion rate (%) = (C0-C1) ÷ C0 x 100%; wherein C0 is the mass content of cyclopentadiene in the cracked C5 fraction, and C1 is the mass content of cyclopentadiene in the product. C0 and C1 are obtained by gas chromatography detection. The purity of the dicyclopentadiene product is obtained by gas chromatography detection.

[0166] Table 1 Mass content ratio of isoprene and cyclopentadiene in cracked C5 fraction

[0167] Serial number C 异戊二烯 / C 环戊二烯 (mass content ratio) Example 3 1.0 Example 4 0.8 Example 5 0.7 Example 6 1.1 Example 7 1.3 Example 8 1.5 Comparative Example 1 0.8 Comparative Example 2 1.5 Comparative Example 3 1.3 Comparative Example 4 1.5

[0168] Table 2 Mass content ratio of isoprene and cyclopentadiene in second depolymerization product

[0169]

[0170]

[0171] Table 3 Operating conditions of dimerization reactor

[0172]

[0173] Table 4 Operating conditions of rectifying column

[0174]

[0175]

[0176] Table 5 Outlet temperature of heat exchanger

[0177]

[0178] Table 6 Operating conditions of cracking reactor and flash tank

[0179]

[0180] Table 7 Operating conditions of cracking reactor and flash tank

[0181]

[0182]

[0183] Table 8 Conversion rate of cyclopentadiene in raw material and purity of dicyclopentadiene product

[0184]

[0185] From the above, it can be seen that the reaction temperature in the first dimerization reactor 11 of Comparative Example 1 is not determined according to Formula 1, and Comparative Example 2 uses C 异戊二烯 / C 环戊二烯The cracking C5 fraction greater than 1 is used as raw material, but only one step of depolymerization-dimerization-distillation is performed, and the reaction temperature in the first dimerization reactor 11 is not determined according to formula 1. The product purity of Comparative Example 1 is obviously lower than that of Example 4, and the conversion rate and product purity of Comparative Example 2 are obviously lower than those of Example 4. Compared with Example 7, the reaction temperature in the second dimerization reactor 21 of the second stage of Comparative Example 3 is not determined according to formula 3. Compared with Example 8, the reaction temperature in the first dimerization reactor 11 of the first stage of Comparative Example 4 is not determined according to formula 1, and the reaction temperature in the second dimerization reactor 21 of the second stage is not determined according to formula 3. The conversion rate and product purity of Comparative Examples 3 and 4 are obviously lower than those of Examples 7 and 8. According to the dimerization selectivity model of each embodiment of the present application, the reaction temperature of dimerization is determined according to the content of isoprene and cyclopentadiene in different cracking C5 fractions, which can improve the selectivity of cyclopentadiene dimerization, and cooperate with other steps in each embodiment of the present application, so as to significantly improve the conversion rate of cyclopentadiene and the purity of dicyclopentadiene product. At the same time, each embodiment of the present application can obtain C 异戊二烯 / C 环戊二烯 The cracking C5 fraction greater than 1 is used as raw material, but only one step of depolymerization-dimerization-distillation is performed, and the reaction temperature in the first dimerization reactor 11 is not determined according to formula 1. The product purity of Comparative Example 1 is obviously lower than that of Example 4, and the conversion rate and product purity of Comparative Example 2 are obviously lower than those of Example 4. Compared with Example 7, the reaction temperature in the second dimerization reactor 21 of the second stage of Comparative Example 3 is not determined according to formula 3. Compared with Example 8, the reaction temperature in the first dimerization reactor 11 of the first stage of Comparative Example 4 is not determined according to formula 1, and the reaction temperature in the second dimerization reactor 21 of the second stage is not determined according to formula 3. The conversion rate and product purity of Comparative Examples 3 and 4 are obviously lower than those of Examples 7 and 8. According to the dimerization selectivity model of each embodiment of the present application, the reaction temperature of dimerization is determined according to the content of isoprene and cyclopentadiene in different cracking C5 fractions, which can improve the selectivity of cyclopentadiene dimerization, and cooperate with other steps in each embodiment of the present application, so as to significantly improve the conversion rate of cyclopentadiene and the purity of dicyclopentadiene product. At the same time, each embodiment of the present application can obtain C 异戊二烯 / C 环戊二烯 The cracking C5 fraction greater than 1 is used as raw material, but only one step of depolymerization-dimerization-distillation is performed, and the reaction temperature in the first dimerization reactor 11 is not determined according to formula 1. The product purity of Comparative Example 1 is obviously lower than that of Example 4, and the conversion rate and product purity of Comparative Example 2 are obviously lower than those of Example 4. Compared with Example 7, the reaction temperature in the second dimerization reactor 21 of the second stage of Comparative Example 3 is not determined according to formula 3. Compared with Example 8, the reaction temperature in the first dimerization reactor 11 of the first stage of Comparative Example 4 is not determined according to formula 1, and the reaction temperature in the second dimerization reactor 21 of the second stage is not determined according to formula 3. The conversion rate and product purity of Comparative Examples 3 and 4 are obviously lower than those of Examples 7 and 8. According to the dimerization selectivity model of each embodiment of the present application, the reaction temperature of dimerization is determined according to the content of isoprene and cyclopentadiene in different cracking C5 fractions, which can improve the selectivity of cyclopentadiene dimerization, and cooperate with other steps in each embodiment of the present application, so as to significantly improve the conversion rate of cyclopentadiene and the purity of dicyclopentadiene product. At the same time, each embodiment of the present application can obtain C 异戊二烯 / C 环戊二烯 The cracking C5 fraction greater than 1 is used as raw material, but only one step of depolymerization-dimerization-distillation is performed, and the reaction temperature in the first dimerization reactor 11 is not determined according to formula 1. The product purity of Comparative Example 1 is obviously lower than that of Example 4, and the conversion rate and product purity of Comparative Example 2 are obviously lower than those of Example 4. Compared with Example 7, the reaction temperature in the second dimerization reactor 21 of the second stage of Comparative Example 3 is not determined according to formula 3. Compared with Example 8, the reaction temperature in the first dimerization reactor 11 of the first stage of Comparative Example 4 is not determined according to formula 1, and the reaction temperature in the second dimerization reactor 21 of the second stage is not determined according to formula 3. The conversion rate and product purity of Comparative Examples 3 and 4 are obviously lower than those of Examples 7 and 8. According to the dimerization selectivity model of each embodiment of the present application, the reaction temperature of dimerization is determined according to the content of isoprene and cyclopentadiene in different cracking C5 fractions, which can improve the selectivity of cyclopentadiene dimerization, and cooperate with other steps in each embodiment of the present application, so as to significantly improve the conversion rate of cyclopentadiene and the purity of dicyclopentadiene product. At the same time, each embodiment of the present application can obtain C

[0186] The above-described specific embodiments further illustrate the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above-described only specific embodiments of the present application, and is not intended to limit the scope of protection of the present application, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A process for the preparation of high purity dicyclopentadiene comprising the steps of: The cracked C5 fraction is sequentially subjected to pre-dimerization, first rectification, depolymerization, dimerization and second rectification to obtain the high-purity dicyclopentadiene; In the dimerization step, the reaction temperature of the dimerization is determined according to the contents of isoprene and cyclopentadiene in the cracked C5 fraction according to the following formula 1, Formula 1: Wherein, S is the dimerization selectivity of cyclopentadiene, and the set value is 0.80 or above; IP is the mass content of isoprene in the cracked C5 fraction; CPD is the mass content of cyclopentadiene in the cracked C5 fraction; T is the reaction temperature of the dimerization, and the unit is Kelvin.

2. The method of preparing high purity dicyclopentadiene according to claim 1, wherein, The preparation method of the high-purity dicyclopentadiene comprises the following steps: (1) The cracked C5 fraction is subjected to pre-dimerization in a pre-dimerization reactor to obtain a pre-dimerization product; (2) The pre-dimerization product is subjected to first rectification in a first rectification column, and the column still of the first rectification column obtains a first rectification product; (3) The first rectification product and carrier gas are subjected to depolymerization in a first cracking reactor to obtain a first depolymerization product; (4) The first depolymerization product is subjected to dimerization in a first dimerization reactor, and the reaction temperature of the dimerization is determined according to the contents of isoprene and cyclopentadiene in the cracked C5 fraction according to the formula 1 to obtain a first dimerization product; (5) The first dimerization product is subjected to second rectification in a second rectification column, and the column still of the second rectification column obtains the high-purity dicyclopentadiene.

3. The method of preparing high purity dicyclopentadiene according to claim 2, wherein, In step (1), the reaction temperature of the pre-dimerization is 40-60℃, the reaction pressure is 0.5-2.5Mpa, and the residence time of the cracked C5 fraction in the pre-dimerization reactor is 35-180min; And / or, in step (1), the pre-dimerization reactor adopts full-column operation, and the feed is from the bottom and the discharge is from the top of the pre-dimerization reactor.

4. The method of preparing high purity dicyclopentadiene according to claim 2, wherein, In step (2), the column still temperature of the first rectification column is 45-85℃, the overhead temperature is 30-50℃, the overhead pressure is 0.03-0.3Mpa, and the reflux ratio is 2-15.

5. The method of preparing high purity dicyclopentadiene according to claim 2, wherein, In step (3), the reaction temperature of the depolymerization is 280-380℃, the reaction pressure is 0.02-0.05Mpa, and the residence time of the first rectification product and carrier gas in the first cracking reactor is 1-15s.

6. The method of preparing high purity dicyclopentadiene according to claim 5, wherein, In step (3), the first rectification product is heated to 120-170℃, then mixed with the carrier gas, and then enters the first cracking reactor; And / or, in step (3), the carrier gas is deoxygenated to have an oxygen content of less than 1ppm, then heated to 280-380℃, then mixed with the first rectification product, and then enters the first cracking reactor; And / or, in step (3), the ratio of the feed mass of the carrier gas to the feed mass of the first rectification product in the first cracking reactor is 1.5 or above.

7. The method of preparing high purity dicyclopentadiene according to claim 2, wherein, Step (3) further comprises: subjecting the product of the first cracking reactor to flash evaporation to separate the carrier gas to obtain the first depolymerization product.

8. The method of preparing high purity dicyclopentadiene according to claim 7, wherein, In step (3), the flash evaporation pressure is 0.01-0.3Mpa, and the temperature is 15-55℃; And / or, in step (3), the product of the first cracking reactor is first heat-exchanged to reach 45-65℃, and then subjected to the flash evaporation.

9. The method of producing high purity dicyclopentadiene according to claim 2, wherein, In step (4), the dimerization reaction temperature is 25-85℃, the reaction pressure is 0.1-3Mpa, and the residence time of the first depolymerization product in the first dimerization reactor is 15-180min. And / or, in step (4), the first dimerization reactor is operated in full tank mode, with the feed being introduced from the bottom and the product being discharged from the top.

10. The method of producing high purity dicyclopentadiene according to claim 2, wherein, In step (5), the column bottom temperature of the second rectification column is 40-85℃, the column top temperature is 30-50℃, the column top pressure is 0.1-0.3Mpa, and the reflux ratio is 2-15.

11. The method of preparing high purity dicyclopentadiene according to claim 2, wherein, The preparation method of the high-purity dicyclopentadiene further comprises the following steps: For a cracking C5 fraction with a mass content ratio of isoprene to cyclopentadiene being 1 or less, the set value of S in formula 1 is 0.95 or more, and after the steps (1) to (5) are performed, the high-purity dicyclopentadiene is obtained; For a cracking C5 fraction with a mass content ratio of isoprene to cyclopentadiene being more than 1, the set value of S in formula 1 is 0.80 to less than 0.95, and after the steps (1) to (5) are performed, the product of step (5) is subjected to a two-stage depolymerization-dimerization-rectification to obtain the high-purity dicyclopentadiene.

12. The method of preparing high purity dicyclopentadiene according to claim 11, wherein, The two-stage depolymerization-dimerization-rectification comprises: (6) introducing the product of step (5) and a carrier gas into a second cracking reactor for depolymerization to obtain a second depolymerization product; (7) introducing the second depolymerization product into a second dimerization reactor for dimerization, and determining the dimerization reaction temperature according to the content of isoprene and cyclopentadiene in the second depolymerization product according to formula 3 to obtain a second dimerization product, Formula 3: wherein S' is the dimerization selectivity of cyclopentadiene in step (7), and the set value is 0.95 or more; IP' is the mass content of isoprene in the second depolymerization product; CPD' is the mass content of cyclopentadiene in the second depolymerization product; and T' is the dimerization reaction temperature in step (7) in Kelvin; (8) introducing the second dimerization product into a third rectification column for third rectification, and obtaining the high-purity dicyclopentadiene from the column bottom of the third rectification column.

13. The method of preparing high purity dicyclopentadiene according to claim 12, wherein, In step (6), the depolymerization reaction temperature is 280-380℃, the reaction pressure is 0.02-0.05Mpa, and the residence time of the product of step (5) and the carrier gas in the second cracking reactor is 1-15s.

14. The method of preparing high purity dicyclopentadiene according to claim 13, wherein, In step (6), the product of step (5) is heat-exchanged to reach 120-170℃, and then mixed with the carrier gas and introduced into the second cracking reactor; And / or, in step (6), the carrier gas is deoxygenated to have an oxygen content of less than 1ppm, heat-exchanged to reach 280-380℃, and then mixed with the product of step (5) and introduced into the second cracking reactor; And / or, in step (6), the ratio of the feed mass of the carrier gas to the feed mass of the product of step (5) in the second cracking reactor is 1.5 or more.

15. The method of preparing high purity dicyclopentadiene of claim 12, wherein, The step (6) further comprises: subjecting the product of the second cracking reactor to flash evaporation to separate the carrier gas, to obtain the second depolymerization product.

16. The method of preparing high purity dicyclopentadiene according to claim 15, wherein, In the step (6), the flash evaporation is performed at a pressure of 0.01-0.3 MPa and a temperature of 15-55°C. In the step (6), the product of the second cracking reactor is first subjected to heat exchange to reach a temperature of 45-65°C, and then subjected to the flash evaporation.

17. The method of making high purity dicyclopentadiene of claim 12, wherein, In the step (7), the dimerization is performed at a temperature of 25-85°C and a pressure of 0.1-3 MPa, and the second depolymerization product is allowed to stay in the second dimerization reactor for 15-180 min. In the step (7), the second dimerization reactor is operated in full tank mode, and the feed is introduced from the bottom and the product is discharged from the top.

18. The method of preparing high purity dicyclopentadiene of claim 12, wherein, In the step (8), the third rectification column is operated at a column bottom temperature of 40-85°C, a column top temperature of 30-50°C, a column top pressure of 0.1-0.3 MPa, and a reflux ratio of 2-15.

19. A system for preparing high-purity dicyclopentadiene, which is used to implement the method for preparing high-purity dicyclopentadiene according to any one of claims 1-18, and which comprises, in sequence, a pre-dimerization unit, a first rectification unit, a first depolymerization unit, a first dimerization unit, and a second rectification unit.

20. The system for preparing high purity dicyclopentadiene of claim 19, wherein, The pre-dimerization unit comprises a pre-dimerization reactor, which is provided with a feed inlet at the bottom and a product outlet at the top. The first rectification unit comprises a first rectification column, which is provided with an inlet, a first light component outlet at the top, and a first rectification product outlet at the column bottom.

21. The system for preparing high purity dicyclopentadiene of claim 20, wherein, The first depolymerization unit comprises a first cracking reactor, which is provided with a feed inlet at the top and a product outlet at the bottom, and the feed inlet of the first cracking reactor is connected to the first rectification product outlet of the first rectification column and a first carrier gas delivery line.

22. The high purity dicyclopentadiene preparation system of claim 21, wherein, The first depolymerization unit further comprises a first heat exchanger, and the feed inlet of the first cracking reactor is connected to the first rectification product outlet of the first rectification column via the first heat exchanger. The first carrier gas delivery line is connected, in sequence, to a second heat exchanger and a first deoxygenation polishing column, so that the carrier gas is subjected to deoxygenation to reduce the oxygen content to less than 1 ppm, and then subjected to heat exchange to reach a temperature of 280-380°C.

23. The high purity dicyclopentadiene preparation system of claim 22, wherein, A first flow controller is further provided between the second heat exchanger and the first deoxygenation polishing column, to control the flow of the carrier gas so that the ratio of the mass of the carrier gas fed into the first cracking reactor to the mass of the first rectification product is greater than 1.

5.

24. The high purity dicyclopentadiene preparation system of claim 21, wherein, The first depolymerization unit further comprises a first flash tank, which is provided with an inlet, a carrier gas outlet, and a first depolymerization product outlet, and the inlet of the first flash tank is connected to the product outlet of the first cracking reactor.

25. The high purity dicyclopentadiene preparation system of claim 24, wherein, The first depolymerization unit further comprises a third heat exchanger, and the inlet of the first flash tank is connected to the product outlet of the first cracking reactor via the third heat exchanger.

26. The high purity dicyclopentadiene preparation system of claim 19, wherein, The first dimerization unit comprises a first dimerization reactor, which is provided with a feed inlet at the bottom and a product outlet at the top. And / or, the second rectification unit comprises a second rectification tower, which is provided with an inlet, the top of the second rectification tower is provided with a second light component outlet, and the bottom is provided with a second rectification product outlet.

27. The high purity dicyclopentadiene production system of claim 19, wherein, The preparation system of the high-purity dicyclopentadiene further comprises a two-stage depolymerization-dimerization-rectification unit, which comprises a second depolymerization unit, a second dimerization unit and a third rectification unit connected in sequence, and is connected to the second rectification unit for continuing to perform depolymerization, dimerization and rectification on the product of the second rectification unit to obtain the high-purity dicyclopentadiene.

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