Cyclopentadiene dimerization method

Abstract

The present invention discloses a cyclopentadiene dimerization method, which comprises: inputting a reaction raw material containing cyclopentadiene into a micro-channel reactor to carry out a dimerization reaction of cyclopentadiene, and adopting a microwave heating mode to carry out the dimerization reaction, wherein the frequency of microwave heating is 1-200GHz, the equivalent hydraulic inner diameter of the microchannel reactor is 10-1000mu m, and finally, the conversion rate of cyclopentadiene in the dimerization reaction is greater than 95%, and the selectivity is greater than 95%. Compared with the prior art, the method provided by the invention can effectively reduce side reactions such as a dimerization reaction of isoprene and cyclopentadiene in a cyclopentadiene dimerization reaction process, improves the conversion rate and selectivity of cyclopentadiene, and has important significance for high-purity and high-yield separation of cyclopentadiene.

Description

Technical Field

[0001] The present invention belongs to the field of cracking C5 fraction separation, and particularly relates to a method for dimerizing cyclopentadiene. Background Art

[0002] Cracking C5 is a by-product generated during the steam cracking of naphtha and other heavy cracking raw materials to produce ethylene. Cracking C5 contains more than 30 components such as alkanes, alkenes, cycloalkanes, cycloalkenes, dienes, bicycloalkenes, alkynes, and enynes with 4-6 carbon atoms. Its composition is complex. Among them, the components with higher value and relatively large content are three dienes: isoprene, cyclopentadiene, and piperylene, and the three of them account for about 40%-55% of cracking C5. Among the above dienes, cyclopentadiene accounts for about 15%-20% of cracking C5. Cyclopentadiene contains a double bond and a methylene group, and is a five-carbon ring containing a conjugated diene bond. Its properties are extremely active, and it is very easy to polymerize into dicyclopentadiene at room temperature. The industrial product of cyclopentadiene also exists in the form of a dimer (i.e., dicyclopentadiene). Dicyclopentadiene can still depolymerize into cyclopentadiene when heated to a certain temperature (176.6°C - 190°C). Cyclopentadiene has active properties and is an intermediate for synthesizing resins, pesticides, pharmaceuticals, spices, etc., and is widely used in unsaturated resins, petroleum resins, metallocene compounds, and new polymer materials. At present, there are more than 200 chemical additives synthesized from cyclopentadiene, and the status of cyclopentadiene in the field of fine chemical production and polymer materials is becoming more and more important.

[0003] The cracked C5 contains more than 30 components. Not only do the boiling points of these components approximate each other, but they can also form binary and ternary azeotropes with each other. Therefore, it is difficult to obtain high-purity cyclopentadiene products using ordinary distillation methods. Currently, the industrial process for separating cyclopentadiene from cracked C5 fractions mainly uses a method of first heating for dimerization and then distilling to separate dicyclopentadiene. The main principle is to first convert cyclopentadiene into dicyclopentadiene through a dimerization reaction, and then utilize the boiling point difference between dicyclopentadiene and other C5 hydrocarbons (the boiling point of dicyclopentadiene is 170 °C) to distill and separate heavy components such as dicyclopentadiene from the C5 hydrocarbons rich in isoprene. Based on the above process flow, a crude cyclopentadiene product with a purity of 70%-90% can be obtained. If a higher-purity cyclopentadiene product is to be produced, the above crude cyclopentadiene product needs to be further refined. The refining process generally can be divided into two categories. One is the rectification method, and the other is the "depolymerization-rectification-dimerization" method. The rectification method is to simply purify crude dicyclopentadiene through rectification operations. In the early stage, most of the processes for preparing high-purity dicyclopentadiene were rectification methods. Both Zeon Corporation of Japan and Japan Synthetic Rubber Co., Ltd. use this method to prepare high-purity dicyclopentadiene products. However, the preparation of high-purity dicyclopentadiene by the rectification method requires multiple rectification operations to achieve. The process conditions are very demanding, the yield is low, and the operating costs and costs are high. The "depolymerization-rectification-dimerization" method first depolymerizes crude dicyclopentadiene to obtain cyclopentadiene, then distills to obtain high-purity cyclopentadiene, and then dimerizes the high-purity cyclopentadiene to obtain high-purity dicyclopentadiene. The methods used by Samsung Corporation of South Korea and Maruzen Petrochemical of Japan to prepare high-purity dicyclopentadiene are relatively typical "depolymerization-rectification-dimerization" methods. This method has low requirements for the rectification column, is easy to operate, and has less loss. It is a method suitable for industrial production.

[0004] For the preparation processes of crude cyclopentadiene products and high-purity dicyclopentadiene products, the dimerization reaction of cyclopentadiene is involved. During the above dimerization reaction process, in addition to the dimerization reaction of cyclopentadiene, the isoprene contained in the reaction materials will also dimerize with cyclopentadiene. Improving the conversion rate of cyclopentadiene and the selectivity of generating dicyclopentadiene during the dimerization reaction process is the key to improving the purity and yield of cyclopentadiene products. At the same time, it can also indirectly improve the purity and yield of isoprene. In the prior art, the dimerization reaction of cyclopentadiene generally uses a reactor type of kettle or tube. The heating method for the dimerization reaction is to introduce steam, heat transfer oil, or electric heating through the jacket outside the reactor. There are many problems in the above dimerization reaction process: (1) If a kettle reactor is used for the dimerization reaction, the backmixing of the reaction materials in the dimerization kettle is serious, the residence time distribution of the materials in the kettle is wide and difficult to accurately control, resulting in a decrease in both the conversion rate and selectivity of the cyclopentadiene dimerization reaction, and indirectly reducing the yield of isoprene.

[0005] Chinese Patent CN101209948B arranges a porous circular plate as a distributor for reaction feed in a vertical reactor to improve the thermal dimerization effect of cyclopentadiene. Although it can, to a certain extent, overcome the irregular flow of materials and increase the conversion rate of the cyclopentadiene dimerization reaction, the backmixing of materials is still relatively serious. There is still a part of isoprene that undergoes a dimerization reaction with cyclopentadiene, resulting in a decrease in the selectivity of the cyclopentadiene dimerization reaction. Moreover, the dimerization reaction time in the above process is relatively long and the efficiency is low.

[0006] If a tubular reactor is used for the dimerization reaction, although the backmixing of reaction materials is reduced to a certain extent, the diameter of the tubular reactor in the prior art is much larger than the transfer size (micrometer level) of "fluid microclusters". That is, although it can be considered that there is almost no backmixing of materials axially, there is still a difference in the concentration of cyclopentadiene radially, resulting in a decrease in the conversion rate and selectivity of the cyclopentadiene dimerization reaction.

[0007] Chinese Patent CN101928197A proposes to set rotating sheets in a tubular reactor to overcome the non-uniformity caused by the difference in the flow rate and reaction temperature of materials in the radial direction in the existing tubular reactor. Although this method can, to a certain extent, eliminate the radial backmixing phenomenon, the reactor structure is too complex, the processing difficulty is large, and it has a certain scale-up effect.

[0008] Whether it is a batch reactor or a tubular reactor, the cyclopentadiene, isoprene and other substances in the reactor are heated simultaneously without distinction by means of heat convection, heat conduction or heat radiation. After cyclopentadiene is heated, it will promote the occurrence of its own dimerization reaction. However, the increase in the temperature of substances such as isoprene will also cause an increase in the side reaction rate between it and cyclopentadiene, which is not conducive to the improvement of the selectivity of cyclopentadiene in the dimerization reaction. At the same time, heat convection, heat conduction or heat radiation are all "from the outside to the inside" heating methods. The above heating methods will lead to the non-uniformity of the temperature field in the reactor. For example, there is an overheating problem at the wall surface, resulting in the non-uniformity of the cyclopentadiene temperature in each region of the reactor. Too high or too low local temperature will cause differences in the cyclopentadiene dimerization reaction rate and an increase in the proportion of side reactions involving isoprene, reducing the conversion rate and selectivity of the cyclopentadiene dimerization reaction, and thus being not conducive to the improvement of the purity and yield in the subsequent cyclopentadiene separation process.

[0009] Patent CN115999473A discloses the application of a microwave microchannel combined reactor, which can be used in chemical synthesis reactions, including halogenation, nitration, sulfonation, diazotization, oxidation, reduction, elimination, alkylation, acylation, condensation, cyclization and rearrangement reactions. However, its application principle is to utilize the characteristics of high heat transfer efficiency and uniform heating of microwaves. In complex systems such as cyclopentadiene dimerization, the raw material composition is complex. Simply combining microwaves and a microchannel reactor, all raw materials are uniformly heated, and it is impossible to solve the problems of serious side reactions and low selectivity in the dimerization reaction.

[0010] Therefore, it can be seen that the prior art still has difficulty in solving the side reaction problem in the cyclopentadiene dimerization reaction, and lacks an effective method to improve the conversion rate and selectivity of cyclopentadiene. Summary of the Invention

[0011] In order to solve the problem of low conversion rate and selectivity of the cyclopentadiene dimerization reaction caused by non-selective and non-uniform heating methods and serious backmixing of materials in the reactor in the prior art, the present invention provides a method for cyclopentadiene dimerization. The method of the present invention adopts a heating method combining a microchannel reactor and microwave heating, and achieves the uniformity of microwave heating by matching a suitable microwave frequency and equivalent hydraulic radius. Under different combinations of microwave frequencies and equivalent hydraulic radii, selective heating of substances with different molecular polarities can be realized. By selectively heating cyclopentadiene, its directional conversion to dicyclopentadiene is promoted, and the reaction time is also shortened.

[0012] To achieve the above object, the present invention provides a method for cyclopentadiene dimerization, which includes: inputting a reaction raw material containing cyclopentadiene into a microchannel reactor for the dimerization reaction of cyclopentadiene, and the heating method of the dimerization reaction adopts microwave heating;

[0013] Among them, the frequency of the microwave heating is 1 - 200 GHz, and the equivalent hydraulic inner diameter of the microchannel reactor is 10 - 1000 μm.

[0014] In the method for cyclopentadiene dimerization of the present invention, preferably, the temperature of the dimerization reaction is 60 - 130 °C, the pressure is 0.15 - 2.5 MPa, and the residence time is 10 - 55 min.

[0015] In the method for cyclopentadiene dimerization of the present invention, preferably, the reaction raw material containing cyclopentadiene is the by-product C5 fraction of the ethylene production device by petroleum cracking, or the C5 fraction after subsequent light hydrocarbon removal, or the crude cyclopentadiene with a cyclopentadiene content of 70% - 90% obtained through preliminary separation.

[0016] The method for dimerizing cyclopentadiene of the present invention, preferably, the frequency of the microwave heating is 50 - 150 GHz, and the frequency of the microwave heating can be adjusted in real time.

[0017] The method for dimerizing cyclopentadiene of the present invention, preferably, the equivalent hydraulic inner diameter of the microchannel reactor is 100 - 700 μm.

[0018] The method for dimerizing cyclopentadiene of the present invention, preferably, the temperature of the dimerization reaction is 80 - 120 °C.

[0019] The method for dimerizing cyclopentadiene of the present invention, preferably, the pressure of the dimerization reaction is 0.5 - 2.0 MPa.

[0020] The method for dimerizing cyclopentadiene of the present invention, preferably, the residence time of the dimerization reaction is 25 - 55 min.

[0021] The method for dimerizing cyclopentadiene of the present invention, preferably, the reaction raw material containing cyclopentadiene is input into the microchannel reactor through a metering pump.

[0022] The present invention has the following advantages compared with the prior art:

[0023] (1) The present invention uses microwave to heat the dimerization reaction of cyclopentadiene in the microchannel reactor. First, the power of the medium absorbing microwave is positively correlated with the molecular polarity of the medium. Therefore, on the premise of ensuring the uniformity of the macroscopic temperature field, microwave heating at a specific frequency can achieve selective heating at the molecular level. Since the molecular polarity of cyclopentadiene is greater than that of isoprene, cyclopentadiene is more easily heated in a microwave environment and then undergoes its own dimerization reaction, indirectly reducing the occurrence of side reactions between it and isoprene. Therefore, for the cyclopentadiene dimerization reaction system, microwave heating has selectivity and can promote the reaction to proceed in the direction of cyclopentadiene dimerization, ultimately improving the selectivity of the cyclopentadiene dimerization reaction.

[0024] (2) Currently, in existing technologies, the dimerization reaction materials are mostly heated in an "outside-in" manner such as thermal convection, heat conduction, or thermal radiation, which has problems such as low heating efficiency. The present invention uses high-frequency microwaves to heat the dimerization reaction materials. Microwave heating is a kind of "volume heating" and is an "instantaneous" internal heating method that realizes molecular-level heating by inducing molecular polarization motion. Moreover, a higher microwave frequency can achieve a greater heating power. Therefore, the heating efficiency corresponding to the high-frequency microwaves used in the present invention is significantly higher than that of traditional heating methods, thereby significantly shortening the time of the dimerization reaction. However, as the microwave frequency increases, the heating depth corresponding to the microwave will decrease. Therefore, the present invention adopts a coupling method of a microchannel reactor and microwave heating for the dimerization reaction of cyclopentadiene, and realizes the heating of the dimerization reaction materials by making the hydraulic size corresponding to the microchannel reactor smaller than the heating depth corresponding to the high-frequency microwaves. In addition, this internal heating mechanism of microwave heating can achieve the temperature uniformity of cyclopentadiene in each region of the reactor within the heating depth during the dimerization reaction, thereby overcoming the existence of temperature gradients in the dimerization reaction environment due to uneven heat transfer in the traditional heat transfer method (typically, the temperature of the material at the wall is higher than the temperature of the main body of the material), and further leading to differences in the dimerization reaction rate of cyclopentadiene and an increase in the proportion of side reactions involving isoprene. Finally, to a certain extent, the conversion rate and selectivity of the cyclopentadiene dimerization reaction are improved.

[0025] (3) The present invention uses a microchannel reactor for the dimerization reaction of cyclopentadiene. Compared with the batch or tubular reactors used in existing technologies, the fluid in the microchannel reactor has a unique flow behavior. The fluid flows orderly in a laminar state, has strong directivity, and the degree of backmixing in the axial and radial directions is greatly reduced. The residence time distribution of the fluid is narrow and can be precisely controlled, thereby effectively reducing side reactions during the dimerization reaction of cyclopentadiene and improving the conversion rate and selectivity of the cyclopentadiene dimerization reaction. Generally speaking, the method provided by the present invention can greatly reduce the proportion of side reactions during the cyclopentadiene dimerization reaction, thereby improving the conversion rate and selectivity of the cyclopentadiene dimerization reaction. Compared with existing technologies, the conversion rate and selectivity are respectively increased by about 5%. Based on the efficient dimerization reaction process of the present invention, combined with other separation processes, the high-yield preparation of high-purity cyclopentadiene can ultimately be achieved. In addition, since there is almost no "scaling effect" in the microchannel reactor, the adjustment of the corresponding product output can be achieved by adjusting the number of parallel reactors, thereby realizing the stepless amplification and effective regulation of the product output.

[0026] (4) Through the method for dimerization of cyclopentadiene of the present invention, ultimately, the conversion rate of cyclopentadiene in the dimerization reaction can be > 95%, and the highest conversion rate can reach 98.6%; the selectivity > 95%, and the highest selectivity can reach 99.1%. Compared with existing technologies, the conversion rate and selectivity of cyclopentadiene are greatly improved; in addition, the reaction time is also greatly shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a flow chart of the cyclopentadiene dimerization method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The following is a detailed description of the embodiments of the present invention: These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually in accordance with conventional conditions.

[0029] The method for dimerizing cyclopentadiene of the present invention has a specific process as Figure 1 shown: The reaction raw material containing cyclopentadiene is input into a microchannel reactor through a metering pump for the dimerization reaction of cyclopentadiene. The heating method for the dimerization reaction is high-frequency microwave heating; the frequency of microwave heating is 1 - 200 GHz. To achieve the uniformity of microwave heating, the equivalent hydraulic inner diameter of the microchannel reactor is 10 - 1000 μm. Based on the difference in molecular polarity between different substances, cyclopentadiene is directionally converted into dicyclopentadiene through the selective heating of microwaves. The temperature of the dimerization reaction is 60 - 130 °C, the pressure is 0.15 - 2.5 MPa, the residence time is 10 - 55 min, and finally, the conversion rate of cyclopentadiene in the dimerization reaction > 95%, and the selectivity > 95%.

[0030] Example 1

[0031] Using the by-product C5 fraction from an ethylene production unit by petroleum cracking in a certain factory as the raw material, the dimerization reaction is carried out by using the cyclopentadiene dimerization method disclosed in the present invention. The composition of the raw material is shown in Table 1.

[0032] Table 1 Analysis of the components of the C5 fraction raw material

[0033]

[0034]

[0035] Note: ∑X1 is benzene and toluene; ∑X2 is the self-dimer formed by C4 dienes.

[0036] The above-mentioned C5 fraction containing cyclopentadiene is fed into a microchannel reactor by a metering pump for the dimerization reaction of cyclopentadiene. The heating method for the dimerization reaction is microwave heating, and the frequency of microwave heating is 2.45 GHz. To achieve the uniformity of microwave heating, the equivalent hydraulic inner diameter of the microchannel reactor is 650 μm. Through the selective heating of microwaves, cyclopentadiene is directionally converted into dicyclopentadiene. The temperature of the dimerization reaction in the microchannel reactor is 80 °C, the reaction pressure is 0.5 MPa, and the reaction residence time is 40 min. After the dimerization reaction, the conversion rate of cyclopentadiene is 96.3%, and the selectivity for conversion to dicyclopentadiene is 96.5%. The composition of the reaction product is shown in Table 2.

[0037] Table 2 Component Analysis of Dimerization Reaction Product

[0038]

[0039]

[0040]

[0041] Note: ∑X3 is the dimer of cyclopentadiene and C4 diene; ∑X4 is the dimer of isoprene and cyclopentadiene; ∑X5 is the self-dimer of isoprene.

[0042] Example 2

[0043] Using the C5 fraction by-product from an ethylene plant's petroleum pyrolysis in a certain factory as the raw material, the dimerization reaction is carried out by the method for dimerizing cyclopentadiene disclosed in the present invention. The composition of the raw material is shown in Table 1.

[0044] The above-mentioned C5 fraction containing cyclopentadiene is fed into a microchannel reactor by a metering pump for the dimerization reaction of cyclopentadiene. The heating method for the dimerization reaction is microwave heating, and the frequency of microwave heating is 1 GHz. To achieve the uniformity of microwave heating, the equivalent hydraulic inner diameter of the microchannel reactor is 1000 μm. Through the selective heating of microwaves, cyclopentadiene is directionally converted into dicyclopentadiene. The temperature of the dimerization reaction in the microchannel reactor is 60 °C, the reaction pressure is 0.15 MPa, and the reaction residence time is 55 min. After the dimerization reaction, the conversion rate of cyclopentadiene is 95.5%, and the selectivity for conversion to dicyclopentadiene is 95.8%. The composition of the reaction product is shown in Table 3.

[0045] Table 3 Component Analysis of Dimerization Reaction Product

[0046]

[0047]

[0048] Example 3

[0049] Using the by - product C5 fraction from the ethylene production unit by petroleum pyrolysis in a certain factory as the raw material, the dimerization reaction is carried out by the method of cyclopentadiene dimerization disclosed in the present invention. The composition of the raw material is shown in Table 1.

[0050] The above - mentioned C5 fraction containing cyclopentadiene is input into the microchannel reactor through a metering pump for the dimerization reaction of cyclopentadiene. Among them, the heating method of the dimerization reaction is microwave heating, and the frequency of microwave heating is 150 GHz. To achieve the uniformity of microwave heating, the equivalent hydraulic inner diameter of the microchannel reactor is 100 μm. Through the selective heating of microwaves, cyclopentadiene is directionally converted into dicyclopentadiene. The temperature of the dimerization reaction in the microchannel reactor is 110 °C, the reaction pressure is 2.0 MPa, and the reaction residence time is 30 min. After the dimerization reaction, the conversion rate of cyclopentadiene is 97.1%, and the selectivity converted to dicyclopentadiene is 96.9%. The composition of the reaction product is shown in Table 4.

[0051] Table 4 Component analysis of the dimerization reaction product

[0052]

[0053]

[0054] Example 4

[0055] Using the material of the by - product C5 fraction after subsequent light hydrocarbon removal from the ethylene production unit by petroleum pyrolysis in a certain factory as the raw material, the dimerization reaction is carried out by the method of cyclopentadiene dimerization disclosed in the present invention. The composition of the raw material is shown in Table 5.

[0056] Table 5 Component analysis of the light - hydrocarbon - removed raw material

[0057]

[0058]

[0059] The above - mentioned C5 fraction containing cyclopentadiene after light hydrocarbon removal is input into the microchannel reactor through a metering pump for the dimerization reaction of cyclopentadiene. Among them, the heating method of the dimerization reaction is microwave heating, and the frequency of microwave heating is 200 GHz. To achieve the uniformity of microwave heating, the equivalent hydraulic inner diameter of the microchannel reactor is 10 μm. Through the selective heating of microwaves, cyclopentadiene is directionally converted into dicyclopentadiene. The temperature of the dimerization reaction in the microchannel reactor is 130 °C, the reaction pressure is 2.5 MPa, and the reaction residence time is 10 min. After the dimerization reaction, the conversion rate of cyclopentadiene is 97.5%, and the selectivity converted to dicyclopentadiene is 97.0%. The composition of the reaction product is shown in Table 6.

[0060] Table 6 Component analysis of the dimerization reaction product

[0061]

[0062]

[0063] Example 5

[0064] Using crude cyclopentadiene with a cyclopentadiene content of 84.8933 wt% obtained by preliminary separation of the by-product C5 fraction from an ethylene production unit in a certain factory as the raw material, the dimerization reaction of cyclopentadiene was carried out by the method for dimerization of cyclopentadiene disclosed in the present invention. The composition of the raw material is shown in Table 7.

[0065] Table 7 Analysis of the components of the crude cyclopentadiene raw material

[0066]

[0067]

[0068] The above-mentioned crude cyclopentadiene with a cyclopentadiene content of 84.8933 wt% was input into a microchannel reactor through a metering pump for the dimerization reaction of cyclopentadiene. Among them, the heating method for the dimerization reaction was microwave heating, and the frequency of microwave heating was 50 GHz. To achieve the uniformity of microwave heating, the equivalent hydraulic inner diameter of the microchannel reactor was 200 μm. Through the selective heating of microwaves, cyclopentadiene was directionally converted into dicyclopentadiene. The temperature of the dimerization reaction in the microchannel reactor was 100 °C, the reaction pressure was 1.0 MPa, and the reaction residence time was 50 min. After the dimerization reaction, the conversion rate of cyclopentadiene was 98.6%, and the selectivity for conversion to dicyclopentadiene was 99.1%. The composition of the reaction product is shown in Table 8.

[0069] Table 8 Analysis of the components of the dimerization reaction product

[0070]

[0071]

[0072] Comparative Example 1

[0073] The composition of the raw material for the dimerization reaction is shown in Table 1.

[0074] The above-mentioned C5 fraction containing cyclopentadiene was input into a stirred reaction kettle for the dimerization reaction of cyclopentadiene to convert cyclopentadiene into dicyclopentadiene. The heating method for the dimerization reaction was heating with heat transfer oil in the jacket outside the reactor. The temperature of the dimerization reaction in the reactor was 80 °C, the pressure was 0.5 MPa, and the average reaction residence time was 420 min. After the dimerization reaction, the conversion rate of cyclopentadiene was 89.2%, and the selectivity for conversion to dicyclopentadiene was 91.3%. The composition of the reaction product is shown in Table 9.

[0075] Table 9 Component Analysis of the Dimerization Reaction Products in the Stirred Kettle

[0076]

[0077]

[0078] Comparative Example 2

[0079] The raw material composition of the dimerization reaction is shown in Table 7.

[0080] The crude cyclopentadiene with a cyclopentadiene content of 84.8933 wt% is fed into a tubular reactor for the dimerization reaction of cyclopentadiene to convert cyclopentadiene into dicyclopentadiene. The heating method of the dimerization reaction is steam heating with an external jacket of the reactor. The temperature of the dimerization reaction in the reactor is 100 °C, the pressure is 1.0 MPa, and the average residence time of the reaction is 360 min. After the dimerization reaction, the conversion rate of cyclopentadiene is 91.4%, and the selectivity for converting to dicyclopentadiene is 92.7%. The composition of the reaction products is shown in Table 10.

[0081] Table 10 Component Analysis of the Dimerization Reaction Products in the Tubular Reactor

[0082]

[0083]

[0084] Comparative Example 3

[0085] The raw material composition of the dimerization reaction is shown in Table 1.

[0086] The above-mentioned C5 fraction containing cyclopentadiene is fed into a microchannel reactor through a metering pump for the dimerization reaction of cyclopentadiene. The heating method of the dimerization reaction is microwave heating, and the frequency of microwave heating is 500 MHz. The equivalent hydraulic inner diameter of the microchannel reactor is 650 μm. Through the selective heating of microwaves, cyclopentadiene is directionally converted into dicyclopentadiene. The temperature of the dimerization reaction in the microchannel reactor is 80 °C, the reaction pressure is 0.5 MPa, and the reaction residence time is 40 min. After the dimerization reaction, the conversion rate of cyclopentadiene is 88.7%, and the selectivity for converting to dicyclopentadiene is 90.7%. The composition of the reaction products is shown in Table 11.

[0087] Table 11 Component Analysis of the Dimerization Reaction Products

[0088]

[0089]

[0090] Comparative Example 4

[0091] The raw material composition of the dimerization reaction is shown in Table 1.

[0092] The above-mentioned C5 fraction containing cyclopentadiene is input into a microchannel reactor through a metering pump for the dimerization reaction of cyclopentadiene. The heating method for the dimerization reaction is microwave heating, with a microwave heating frequency of 2.45 GHz. The equivalent hydraulic inner diameter of the microchannel reactor is 8000 μm. Through the selective heating of microwaves, cyclopentadiene is directionally converted into dicyclopentadiene. The temperature of the dimerization reaction in the microchannel reactor is 80 °C, the reaction pressure is 0.5 MPa, and the reaction residence time is 40 min. After the dimerization reaction, the conversion rate of cyclopentadiene is 86.5%, and the selectivity for conversion to dicyclopentadiene is 89.9%. The composition of the reaction product is shown in Table 12.

[0093] Table 12 Component analysis of the dimerization reaction product

[0094]

[0095]

[0096] It can be seen from the results of Example 1 and Comparative Example 1, Example 5 and Comparative Example 2 that the side reactions during the dimerization reaction of cyclopentadiene are relatively high in a batch reactor or a tubular reactor, and the conversion rate and selectivity of the cyclopentadiene dimerization reaction are relatively low. The method of cyclopentadiene dimerization combining the microchannel reactor and microwave heating of the present invention can effectively reduce the side reactions during the cyclopentadiene dimerization reaction, improve the conversion rate and selectivity of the cyclopentadiene dimerization reaction, and the conversion rate and selectivity are increased by more than 5% respectively.

[0097] It can be seen from the results of Example 1 and Comparative Examples 3 and 4 that adjusting the microwave heating frequency or the equivalent hydraulic inner diameter of the microchannel reactor too large will instead reduce the conversion rate and selectivity of the cyclopentadiene dimerization reaction. Therefore, when using the method of coupling a microchannel reactor and microwave heating, it is necessary to select an appropriate microwave heating frequency or the equivalent hydraulic inner diameter of the microchannel reactor. The microwave heating frequency of 1 - 200 GHz and the equivalent hydraulic inner diameter of 10 - 1000 μm of the microchannel reactor of the present invention can effectively improve the conversion rate and selectivity of the cyclopentadiene dimerization reaction.

[0098] Certainly, the present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the present invention.

Claims

1. A method for dimerizing cyclopentadiene, It is characterized in that include: The reaction raw materials containing cyclopentadiene are introduced into a microchannel reactor to carry out a dimerization reaction of cyclopentadiene, and the dimerization reaction is heated by microwave heating; Wherein, the frequency of the microwave heating is 1-200 GHz, and the equivalent hydraulic inner diameter of the microchannel reactor is 10-1000 μm.

2. The method for dimerization of cyclopentadiene according to claim 1, It is characterized in that The dimerization reaction temperature is 60-130° C., the pressure is 0.15-2.5 MPa, and the residence time is 10-55 min.

3. The method for dimerization of cyclopentadiene according to claim 1, It is characterized in that The reaction raw material containing cyclopentadiene is a by-product C5 fraction of a petroleum cracking ethylene production unit, or a C5 fraction after subsequent removal of light hydrocarbons, or a crude cyclopentadiene obtained through preliminary separation.

4. The method for dimerization of cyclopentadiene according to claim 1, It is characterized in that The frequency of the microwave heating is 50-150 GHz.

5. The method for dimerization of cyclopentadiene according to claim 1, It is characterized in that The equivalent hydraulic inner diameter of the microchannel reactor is 100-700 μm.

6. The method for dimerization of cyclopentadiene according to claim 1, It is characterized in that The dimerization reaction temperature is 80-120°C.

7. The method for dimerization of cyclopentadiene according to claim 1, It is characterized in that The dimerization reaction pressure is 0.5-2.0 MPa.

8. The method for dimerization of cyclopentadiene according to claim 1, It is characterized in that The residence time of the dimerization reaction is 25-55 min.

9. The method for dimerization of cyclopentadiene according to claim 1, It is characterized in that The reaction raw materials containing cyclopentadiene are fed into the microchannel reactor through a metering pump.

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