Preparation process of tetrahydrofuran

Abstract

The invention belongs to the technical field of tetrahydrofuran preparation, and particularly relates to a preparation process of tetrahydrofuran. The preparation process comprises the following steps: 1, introducing 1, 4-butanediol into a catalytic reaction area of a reactor, and carrying out a dehydration cyclization reaction to obtain a gas-phase product and a liquid-phase product; and 2, discharging the liquid-phase product out of the reactor along an annular region between the catalytic reaction region and the inner wall of the reactor. And 3, sequentially carrying out rectification treatment and condensation treatment on the gas-phase product, and separating out tetrahydrofuran and a circular reaction liquid. And 4, mixing the circular reaction liquid with 1, 4-butanediol, and repeating the step 1. Therefore, by removing the liquid-phase product and discharging the gas-phase product in time, the reaction can be promoted to proceed forwards, and the reaction conversion rate can be increased; the recycling of the circular reaction liquid avoids the waste of resources, and greatly reduces the energy consumption and the raw material input, so that the reaction conversion rate can be improved while the production cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of tetrahydrofuran preparation, and particularly to a preparation process of tetrahydrofuran. Background Art

[0002] Tetrahydrofuran (THF), as a strong polar solvent, has a powerful dissolving ability and can dissolve numerous organic substances, playing an irreplaceable role in the field of organic synthesis. At the same time, it is also a key raw material for preparing various polymers such as polycarbonate, polyether ester, polyolefin, and polyurethane, and also occupies an important position in the pharmaceutical industry, where it can be used to prepare various pharmaceutical ingredients. In addition, THF is widely used in products such as coatings, plastics, and rubbers as an additive, and even in the battery manufacturing process, it can be used as a component of the electrolyte.

[0003] In the related art, the processes for producing THF include the furfural method, the maleic anhydride direct hydrogenation method, and the 1,4-butanediol (BDO) dehydration method. Among them, the furfural method has been gradually phased out due to complex process and serious pollution. The maleic anhydride direct hydrogenation method has high requirements for equipment due to high-pressure reaction and acidic raw materials, with high fixed investment and operating costs. The BDO dehydration method has become the main method due to low reaction temperature, low pressure, and high yield. However, in this method, the reaction conversion rate is low, and a large amount of unreacted BDO needs to be recycled, resulting in high production costs. Summary of the Invention

[0004] In view of the above problems, the present application is proposed. The present application provides a preparation process of tetrahydrofuran.

[0005] According to one aspect of the present application, there is provided a preparation process of tetrahydrofuran, including:

[0006] Step 1: Pass 1,4-butanediol into the catalytic reaction area of the reactor for dehydration cyclization reaction to obtain a gas-phase product and a liquid-phase product;

[0007] Step 2: Discharge the liquid-phase product along the annular area between the catalytic reaction area and the inner wall of the reactor;

[0008] Step 3: Successively perform rectification treatment and condensation treatment on the gas-phase product to separate tetrahydrofuran and the circulating reaction liquid;

[0009] Step 4: Mix the circulating reaction liquid with 1,4-butanediol and repeat Step 1.

[0010] Compared with the prior art, the preparation process of tetrahydrofuran provided in the present application first introduces 1,4-butanediol into the catalytic reaction area of the reactor for dehydration cyclization reaction to obtain gas phase products and liquid phase products. Then, the liquid phase product is discharged from the reactor along the annular area between the catalytic reaction area and the inner wall of the reactor. Compared with the gas phase product, the liquid phase product belongs to the heavy component and can be discharged from the reactor along the annular area between the catalytic reaction area and the inner wall of the reactor. It can be seen that the annular area provides additional flow space for the liquid phase product, which effectively realizes the separation efficiency and collection efficiency of the liquid phase product. In addition, after the dehydration cyclization reaction is completed, the generated liquid phase product contains substances that do not participate in the reaction. As the reaction proceeds in the forward direction, these unreacted substances continue to accumulate in the reaction system, will cover the catalyst surface in the catalytic reaction area, hinder the effective contact between BDO and the catalyst, and reduce the activity of the catalyst. Therefore, when these unreacted substances are discharged from the reactor together with the liquid phase product, the concentration of unreacted substances in the reaction system is effectively reduced, and a high catalyst activity can be maintained, which is conducive to improving the reaction conversion rate. Secondly, the gas phase product is subjected to rectification treatment and condensation treatment in sequence to separate tetrahydrofuran and circulating reaction liquid. This step can accurately separate tetrahydrofuran and circulating reaction liquid. This effective product separation method not only ensures the purity of the product tetrahydrofuran, but also allows the recyclable reaction liquid to be recovered, providing a guarantee for continuous and efficient production. It can be seen that by removing the liquid phase product and discharging the gas phase product in time, the reaction can be promoted to proceed in the forward direction, which is conducive to improving the reaction conversion rate.

[0011] Finally, the circulating reaction liquid is mixed with 1,4-butanediol and step 1 is repeated. Compared with the process of using raw materials once, this step greatly reduces energy consumption and raw material input, and reduces the probability of recovering a large amount of unreacted BDO, thereby reducing production costs while improving reaction conversion rate.

[0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the technology as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0014] Figure 1 A schematic flow chart of the preparation process of tetrahydrofuran according to an embodiment of the present application is shown;

[0015] Figure 2 The structural schematic diagram of the reactor according to the embodiment of the present application is shown.

[0016] Reference numerals:

[0017] 1 - reactor body; 101 - feed channel; 102 - gas-phase product channel; 103 - annular region; 104 - fluid channel; 2 - central flow channel; 3 - catalytic reaction region; 4 - support structure; 5 - raw material distribution structure and 6 - buffer. Detailed implementation manners

[0018] In order to make the objectives, technical solutions and advantages of the present application more obvious, the exemplary embodiments according to the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. It should be understood that the present application is not limited by the exemplary embodiments described herein.

[0019] As a strong polar solvent, THF has a powerful dissolving ability and can dissolve many organic substances, playing an irreplaceable role in the field of organic synthesis. At the same time, it is also a key raw material for preparing various polymers such as polycarbonate, polyether ester, polyolefin and polyurethane, and also occupies an important position in the pharmaceutical industry and can be used to prepare various pharmaceutical ingredients. In addition, THF is widely used in products such as coatings, plastics and rubbers as an additive. Even in the process of battery manufacturing, it can be used as a component of the electrolyte.

[0020] In the related art, the processes for producing tetrahydrofuran include the furfural method, the maleic anhydride direct hydrogenation method and the BDO dehydration method. Among them, the furfural method has been gradually phased out due to complex process and serious pollution. The maleic anhydride direct hydrogenation method has high requirements for equipment due to high-pressure reaction and acidic raw materials, with high fixed investment and operating costs. The BDO dehydration method is to carry out a dehydration reaction on BDO under the condition of acid catalysis to produce THF, and has become the main method due to low reaction temperature, low pressure and high yield. However, when producing THF by this method, the reaction conversion rate is low and a large amount of unreacted BDO needs to be recovered.

[0021] In view of the above problems, the present application provides a preparation process for tetrahydrofuran, which can improve the reaction conversion rate while reducing the production cost. Figure 1 The process flow schematic diagram of the preparation process for tetrahydrofuran according to the embodiment of the present application is shown. As Figure 1 shown, the method includes:

[0022] Step 1, introducing 1,4-butanediol into the catalytic reaction region of the reactor to carry out a dehydration cyclization reaction to obtain a gas-phase product and a liquid-phase product.

[0023] Step 2, discharging the liquid-phase product out of the reactor along the annular region between the catalytic reaction region and the inner wall of the reactor.

[0024] Exemplarily, compared with the gas-phase product, the liquid-phase product belongs to the heavy component and can be discharged from the reactor along the annular region between the catalytic reaction zone and the inner wall of the reactor. It can be seen that the annular region provides additional flow space for the liquid-phase product, effectively realizing the separation efficiency and collection efficiency of the liquid-phase product.

[0025] It can be understood that after the dehydration cyclization reaction is completed, the generated liquid-phase product contains substances that have not participated in the reaction. As the reaction proceeds forward, these unreacted substances accumulate continuously in the reaction system, cover the surface of the catalyst in the catalytic reaction zone, hinder the effective contact between BDO and the catalyst, and reduce the activity of the catalyst. Therefore, when these unreacted substances are discharged from the reactor together with the liquid-phase product, the concentration of unreacted substances in the reaction system is effectively reduced, and a relatively high catalyst activity can be maintained, which is conducive to improving the reaction conversion rate.

[0026] Step 3: Perform rectification treatment and condensation treatment on the gas-phase product in sequence to separate tetrahydrofuran and the recycle reaction liquid.

[0027] Exemplarily, through the rectification and condensation treatment of the gas-phase product in this step, tetrahydrofuran and the recycle reaction liquid can be accurately separated. This effective product separation method not only ensures the purity of the product tetrahydrofuran, but also enables the recyclable reaction liquid to be recovered, providing guarantee for continuous and efficient production. It can be seen that by removing the liquid-phase product and discharging the gas-phase product in a timely manner, the forward reaction can be promoted, which is conducive to improving the reaction conversion rate.

[0028] Step 4: Mix the recycle reaction liquid with 1,4-butanediol and repeat Step 1.

[0029] Exemplarily, the repeated use of the recycle reaction liquid avoids waste of resources. Compared with the process of using raw materials once, it greatly reduces energy consumption and raw material input, reduces the probability of needing to recover a large amount of unreacted BDO, and thus can reduce production costs while improving the reaction conversion rate. Moreover, the continuity of this preparation process is good, which is conducive to stabilizing the production process, facilitating large-scale industrial production, improving production efficiency, and reducing fluctuations and uncertainties in the production process.

[0030] In an optional manner, Step 1 in the embodiments of the present application includes: introducing 1,4-butanediol into the catalytic reaction zone of the reactor in a radial centrifugal manner to carry out a dehydration cyclization reaction to obtain a gas-phase product and a liquid-phase product. Figure 2 The structural schematic diagram of the reactor according to the embodiments of the present application is shown. As Figure 2As shown in the figure, the reactor of the embodiment of the present application includes a reactor body 1, a central flow channel 2 and a catalytic reaction region 3 provided in the reactor body 1. Among them, the central flow channel 2 is provided at the axial center of the reactor body 1, and a plurality of radial openings are distributed along the axial direction on the side wall of the central flow channel 2. The catalytic reaction region 3 is located between the central flow channel 2 and the inner wall of the reactor body 1. It should be understood that Figure 2 the reactor body 1 in Figure 1 is actually the

[0031] reactor in

[0032] In practical applications, as Figure 2 shown in the figure, the reactor of the embodiment of the present application further includes a support structure 4 and a raw material distribution structure 5. Among them, the support structure is provided at one end of the central flow channel 2 facing the bottom of the reactor body 1 and is fixedly connected to the inner wall of the reactor body 1, which can ensure that after BDO enters the reactor body 1, it will not directly enter the catalytic reaction region 3, but enter the central flow channel 2, which helps to maintain the stability of the reaction process. The bottom end of the reactor body 1 has a feed channel 101, and the raw material distribution structure 5 is provided at one end of the feed channel 101 close to the central flow channel 2. Therefore, BDO can enter the reactor body 1 through the feed channel 101 at the bottom end of the reactor body 1. Under the action of the raw material distribution structure 5, the raw materials can enter the central flow channel 2 evenly and stably, so that the reaction can proceed under relatively stable conditions, reducing the changes in parameters such as reaction temperature and pressure caused by feed fluctuations, which is beneficial to improving the stability of product quality and reducing the fluctuation of product quality. In addition, the top end of the reactor body 1 has a gas-phase product channel 102, there is an annular region 103 between the catalytic reaction region 3 and the inner wall of the reactor body 1, and a fluid channel 104 is provided on the side wall of the reactor body 1. The fluid channel 104 is communicated with the annular region 103. Therefore, during the dehydration cyclization process, the gas-phase product flows upward and is discharged from the reactor body 1 through the gas-phase product channel 102 for rectification treatment and condensation treatment. Similarly, the circulating reaction liquid can also enter the reactor body 1 through the fluid channel 104 for circulating reaction. That is to say, in step two, the liquid-phase product is collected along the annular region to the fluid channel and then discharged from the reactor body.

[0033] Moreover, a plurality of buffer members 6 can be evenly distributed in the axial direction of the central flow channel. In the spatial dimension, the buffer members 6 can divide the catalytic reaction region 3 into multiple catalytic reaction spaces. Secondly, when the reaction temperature in the reactor body 1 rapidly rises from room temperature to several hundred degrees Celsius, the size of the central flow channel 2 will significantly increase. The buffer members 6 can absorb the thermal expansion caused by the temperature change at the temperature level, avoiding problems such as cracks and leaks due to inconsistent expansion between components. Moreover, when there is a high pressure in the reactor body 1, the buffer members 6 can bear part of the stress generated by the pressure, reducing the pressure load on the central flow channel 2 and improving the pressure resistance of the reactor body 1. It should be understood that the buffer member can be an expansion ring or other components that can achieve the above functions, and can be adjusted according to the actual situation, which is not limited here.

[0034] In addition, the embodiment of the present application can also optimize the opening scheme of the central flow channel by means of computational fluid dynamics flow field simulation technology, making the fluid distribution inside the reactor body more uniform, thereby effectively improving the mixing condition and mass transfer efficiency of BDO and / or the circulating reaction liquid, and achieving the purpose of increasing the BDO conversion rate.

[0035] Exemplarily, the rotational speed of the radial centrifugation in the embodiment of the present application is 30 revolutions per minute to 60 revolutions per minute. Within this range, the centrifugal force of the radial centrifugation in the embodiment of the present application is moderate, which can ensure that BDO can flow radially uniformly and fully contact the catalyst in the catalytic reaction region, facilitating the improvement of the reaction efficiency and conversion rate. If the rotational speed of the radial centrifugation in the embodiment of the present application is lower than 30 revolutions per minute, at this time, the centrifugal force of the radial centrifugation is low, which easily leads to uneven distribution of BDO in the catalytic reaction region, thus being disadvantageous for increasing the BDO conversion rate. If the rotational speed of the radial centrifugation in the embodiment of the present application is higher than [revolutions per minute], at this time, the centrifugal force of the radial centrifugation is high, and when it scours the catalyst at a high speed, it is easy to cause the catalyst to break or be lost, thus increasing the production cost.

[0036] Exemplarily, the packing density of the catalyst in the catalytic reaction region in the embodiment of the present application is 200 kg / m 3 ~400 kg / m 3 . Within this range, the catalyst can be evenly distributed in the catalytic reaction region, providing sufficient active sites for the dehydration cyclization reaction, which is beneficial to improving the reaction rate and the BDO conversion rate. If the packing density in the embodiment of the present application is lower than 200 kg / m 3 , at this time, the active sites of the catalyst per unit volume are insufficient, making it impossible for BDO and the circulating reaction liquid to fully contact the catalyst, resulting in a decrease in the BDO conversion rate. If the packing density in the embodiment of the present application is higher than 400 kg / m 3, at this time, BDO and the circulating reaction liquid are difficult to penetrate into the interior of the catalyst, thereby having an adverse effect on the conversion rate of BDO.

[0037] It can be understood that the catalytic reaction region in the embodiments of the present application includes a support assembly and a plurality of catalysts. The catalyst support assembly includes a plurality of superimposed corrugated supports, and the inclination directions of the corrugations of two adjacent corrugated supports are opposite. The plurality of catalysts are fixed in the corrugated supports, so that when BDO and the circulating reaction liquid pass through the catalyst bed, the flow path continuously changes, promoting the more sufficient contact between the reaction liquid and the catalyst, improving the reaction efficiency, greatly saving the catalyst dosage, and saving investment. Among them, there is a gap between two adjacent corrugated supports, and the plurality of catalysts are fixed in the gap and / or the corrugations, which can effectively prevent the displacement or shaking of the catalyst during the contact with the reaction liquid. It should be understood that the corrugated support in the embodiments of the present application can be a corrugated structured packing or other supports that can achieve the above purposes, and can be adjusted according to actual situations, and is not limited herein. In addition, the catalysts in the embodiments of the present application can be coated with a flexible mesh carrier to reduce the friction frequency and intensity of the catalyst during the contact with the reaction liquid, and reduce the probability of catalyst accumulation and blockage caused by poor flow of the reaction liquid. The specific selection of the material of the flexible mesh carrier can be adjusted according to actual situations and is not limited herein.

[0038] Exemplarily, in Step 1 and Step 4, the flow rate of BDO and / or the circulating reaction liquid on the catalytic reaction region in the embodiments of the present application is 1 m 3 / h to 3 m 3 / h. When within this range, while ensuring the full progress of the dehydration cyclization reaction, it can avoid the occurrence of side reactions caused by the too long residence time of BDO and / or the circulating reaction liquid. If the flow rate is lower than 1 m 3 / h, the rate of the dehydration cyclization reaction will be reduced, and the probability of side reactions will be greatly increased, having an adverse effect on the purity of THF. If the flow rate is higher than 3 m 3 / h, it will cause BDO and / or the circulating reaction liquid to leave the catalytic reaction region without sufficient reaction, thereby reducing the reaction conversion rate.

[0039] In an alternative manner, in Step 1 and Step 4, the temperature of the dehydration cyclization reaction in the embodiments of the present application is 100°C to 140°C, and the pressure of the dehydration cyclization reaction in the embodiments of the present application is 0.05 Mpa to 0.2 Mpa. Within the above ranges, it can ensure the gasification of THF, maintain the full liquid-phase reaction, and make the BDO conversion rate as high as 100%. If the temperature of the dehydration cyclization reaction is lower than 100°C and the pressure of the dehydration cyclization reaction is lower than 0.05 Mpa, it will not only significantly reduce the reaction rate, but also cause some BDO or THF to gasify in advance, destroying the full liquid-phase reaction conditions. If the temperature of the dehydration cyclization reaction is higher than 140°C and the pressure of the dehydration cyclization reaction is higher than 0.2 Mpa, it will not only increase the generation amount of by-products (such as dihydrofuran), increase the separation difficulty and treatment cost, but also increase the difficulty of removing the reaction heat, and is prone to local overheating.

[0040] In an alternative manner, before Step 1, the above process further includes: heating BDO, which can make the temperature of BDO close to or reach the catalyst activation temperature, shortening the heating-up time in the reactor.

[0041] In an alternative manner, before Step 4, the above process further includes: heating the circulating reaction liquid, which can make the temperature of the circulating reaction liquid close to or reach the catalyst activation temperature, shortening the heating-up time in the reactor.

[0042] In an alternative manner, Step 4 in the present application further includes: discharging the reacted circulating reaction liquid out of the reactor along the annular region between the catalytic reaction region and the inner wall of the reactor. Specifically, the reacted circulating reaction liquid is collected along the annular region to the fluid channel and then discharged out of the reactor. During this process, the components that do not participate in the reaction in the circulating reaction liquid are removed, and the gaseous products generated by the reacted circulating reaction liquid are discharged out of the reactor, promoting the forward progress of the chemical reaction, so that the reaction conversion rate can be increased while reducing the production cost.

[0043] To illustrate the effects of the preparation process of tetrahydrofuran provided by the present application, the following is described by using examples.

[0044] Example 1

[0045] Step 1: After heating the BDO liquid, it is introduced into the central flow channel from the bottom of the reactor body through the raw material distribution structure, and flows through the catalytic reaction region in a radially centrifugal manner to undergo a cyclization dehydration reaction, generating a gas-phase product and a liquid-phase product.

[0046] Among them, the temperature of the dehydration cyclization reaction is 120°C, the pressure of the dehydration cyclization reaction is 0.1 Mpa, the radially centrifugal speed is 40 revolutions per minute, and the filling density of the catalyst is 300 kg / m 3, the flow rate of the BDO liquid over the catalytic reaction area is 1.5 m 3 / h, and the temperature of the heat treatment is 160 °C.

[0047] Step Two: After collecting the liquid-phase product along the annular area into the fluid channel, discharge it from the reactor body.

[0048] Step Three: Perform rectification treatment and condensation treatment on the gas-phase product in sequence to separate out THF and the recycled reaction liquid.

[0049] Step Four: After heating the recycled reaction liquid, repeat Step One, and after collecting the reacted recycled reaction liquid along the annular area into the fluid channel, discharge it from the reactor. Finally, the conversion rate of BDO is calculated to be 100% by measuring the production amount of THF.

[0050] Among them, the temperature of the heat treatment is 160 °C.

[0051] Example Two

[0052] Step One: After heating the BDO liquid, introduce it from the bottom of the reactor body into the central flow channel through the raw material distribution structure, and flow through the catalytic reaction area in a radially centrifugal manner to carry out a cyclization dehydration reaction to generate a gas-phase product and a liquid-phase product.

[0053] Among them, the temperature of the dehydration cyclization reaction is 115 °C, the pressure of the dehydration cyclization reaction is 0.15 Mpa, the rotation speed of the radial centrifugation is 50 revolutions per minute, and the packing density of the catalyst is 250 kg / m 3 , the flow rate of the BDO liquid over the catalytic reaction area is 1 m 3 / h, and the temperature of the heat treatment is 160 °C.

[0054] Step Two: After collecting the liquid-phase product along the annular area into the fluid channel, discharge it from the reactor body.

[0055] Step Three: Perform rectification treatment and condensation treatment on the gas-phase product in sequence to separate out THF and the recycled reaction liquid.

[0056] Step Four: After heating the recycled reaction liquid, repeat Step One, and after collecting the reacted recycled reaction liquid along the annular area into the fluid channel, discharge it from the reactor. Finally, the conversion rate of BDO is calculated to be 99.8% by measuring the production amount of THF.

[0057] Among them, the temperature of the heat treatment is 160 °C.

[0058] Example Three

[0059] Step 1: After heating the BDO liquid, it is introduced into the central flow channel from the bottom of the reactor body through the raw material distribution structure and flows through the catalytic reaction area in a radial centrifugal manner to undergo a cyclodehydration reaction, generating a gas-phase product and a liquid-phase product.

[0060] Among them, the temperature of the dehydration cyclization reaction is 130 °C, the pressure of the dehydration cyclization reaction is 0.15 Mpa, the rotational speed of the radial centrifugation is 30 revolutions per minute, and the packing density of the catalyst is 300 kg / m 3 , the flow rate of the BDO liquid on the catalytic reaction area is 1 m 3 / h, and the temperature of the heating treatment is 160 °C.

[0061] Step 2: After the liquid-phase product is collected along the annular area into the fluid channel, it is discharged from the reactor body.

[0062] Step 3: The gas-phase product is subjected to rectification treatment and condensation treatment in sequence to separate THF and the recycled reaction liquid.

[0063] Step 4: After heating the recycled reaction liquid, repeat Step 1, and after the recycled reaction liquid after the reaction is collected along the annular area into the fluid channel, it is discharged from the reactor. Finally, the conversion rate of BDO is calculated to be 100% by measuring the production amount of THF.

[0064] Among them, the temperature of the heating treatment is 160 °C.

[0065] It can be seen that the preparation process of tetrahydrofuran provided by the embodiments of the present application can reduce the production cost while maximizing the reaction conversion rate, and there is no need to recover a large amount of unreacted BDO.

[0066] The above is only the specific implementation manner of the present application. Obviously, various modifications and combinations can be made without departing from the spirit and scope of the present application. Accordingly, this specification and the drawings are only exemplary illustrations of the present application defined by the appended claims, and are considered to have covered any and all modifications, variations, combinations or equivalents within the scope of the present application. Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the intention of the present application includes these changes and modifications. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present application, and all should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0067] It should also be noted that in the apparatus and method of the present application, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations shall be regarded as equivalent solutions of the present application.

[0068] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present application. Thus, the present application is not intended to be limited to the aspects shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0069] The above description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the form disclosed herein. Although several example aspects and embodiments have been discussed above, those skilled in the art will recognize some of their variations, modifications, alterations, additions, and sub - combinations.

Claims

1. A preparation process of tetrahydrofuran, characterized in that, Including: Step 1: Feed 1,4-butanediol into the catalytic reaction zone of the reactor for dehydration cyclization reaction to obtain a gas-phase product and a liquid-phase product; Step 2: Discharge the liquid-phase product out of the reactor along the annular region between the catalytic reaction zone and the inner wall of the reactor; Step 3: Successively perform rectification treatment and condensation treatment on the gas-phase product to separate tetrahydrofuran and a recycled reaction liquid; Step 4: Mix the recycled reaction liquid with the 1,4-butanediol and repeat Step 1.

2. The preparation process of tetrahydrofuran according to claim 1, characterized in that, The said Step 1 includes: Feed 1,4-butanediol into the catalytic reaction zone of the reactor in a radially centrifugal manner for dehydration cyclization reaction to obtain a gas-phase product and a liquid-phase product.

3. The preparation process of tetrahydrofuran according to claim 2, wherein, The rotational speed of the said radial centrifugation is 30 revolutions per minute to 60 revolutions per minute.

4. The preparation process of tetrahydrofuran according to claim 1, characterized in that, The packing density of the catalyst in the catalytic reaction zone is 200 kg / m 3 ~ 400 kg / m 3 .

5. The preparation process of tetrahydrofuran according to claim 1, characterized in that, In the first step and the fourth step, the flow rate of 1,4-butanediol and / or the circulating reaction solution on the catalytic reaction region is 1 m 3 / h to 3 m 3 / h.

6. The preparation process of tetrahydrofuran according to claim 1, characterized in that, In the said Step 1 and Step 4, the temperature of the dehydration cyclization reaction is 100°C to 140°C, and the pressure of the dehydration cyclization reaction is 0.05 Mpa to 0.2 Mpa.

7. The preparation process of tetrahydrofuran according to any one of claims 1 to 6, characterized in that, Before the said Step 1, the process further includes: Perform a heating treatment on 1,4-butanediol.

8. The preparation process of tetrahydrofuran according to any one of claims 1 to 6, characterized in that, Before the said Step 4, the process further includes: Perform a heating treatment on the recycled reaction liquid.

9. The preparation process of tetrahydrofuran according to any one of claims 1 to 6, characterized in that, The said Step 4 further includes: Discharge the recycled reaction liquid after the reaction out of the reactor along the annular region between the catalytic reaction zone and the inner wall of the reactor.

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