Apparatus for preparing cyclododecanol and method of preparing cyclododecanol

Abstract

The application relates to the technical field of fine chemical industry, in particular to a cyclododecanol preparation device and a preparation method thereof. The cyclododecanol preparation device comprises a high-pressure hydrogenation reactor and a reaction liquid circulating pump; the high-pressure hydrogenation reactor comprises a second fixed bed, the second fixed bed is filled with a second catalyst, second reaction raw materials can flow through the second catalyst on the second fixed bed to carry out a hydrogenation reaction, and the reaction liquid circulating pump is used for sending at least part of reaction liquid obtained after the hydrogenation reaction back to the high-pressure hydrogenation reactor and making the reaction liquid flow through the second catalyst on the second fixed bed. The preparation device can avoid a dry catalyst bed, reduce the risk of a violent exothermic side reaction of small molecular alcohol adsorbed by the catalyst, improve the problems of reactor temperature runaway and overpressure, and greatly improve the safety of the system.

Description

Technical Field

[0001] This disclosure relates to the field of fine chemical technology, and in particular to an apparatus and method for preparing cyclododecyl alcohol. Background Technology

[0002] Cyclododecyl alcohol (CDOL, CAS No. 1724-39-6, molecular formula C) 12 H 24 O) is an important intermediate in the Nylon 12 (PA12) industrial chain. Its main use is in the dehydrogenation preparation of CDON (cyclododecanone, CAS No. 830-13-7, molecular formula C). 12 H 22 O).

[0003] CDOL can be derived from 9,10-epoxy-1,5-cyclododecadiene (EPO, CAS No. 943-93-1) or epoxycyclododecane (ECDA, CAS No. 286-99-7, molecular formula C). 12 H 22 O) is obtained through hydrogenation. The hydrogenation of EPO requires the hydrogenation of two carbon-carbon double bonds and one epoxy bond; the hydrogenation of ECDA requires the hydrogenation of one epoxy bond. Both hydrogenation reactions involve high reaction pressure and large amounts of heat release, resulting in high production risks. To efficiently remove heat and improve the safety and controllability of the hydrogenation reaction, while ensuring selectivity, a small molecule alcohol is generally added as a solvent. This small molecule alcohol not only dilutes the reactants but also increases the solubility of hydrogen in the liquid phase, enhancing mass transfer in the hydrogenation reaction.

[0004] However, in actual production, it has been found that the addition of small molecule alcohols can cause reactor overheating and overpressure from time to time, bringing additional process safety risks. Summary of the Invention

[0005] Based on this, the first aspect of this disclosure provides an apparatus for preparing CDOL, the technical solution of which is as follows: An apparatus for preparing CDOL includes a high-pressure hydrogenation reactor and a reaction liquid circulation pump; the high-pressure hydrogenation reactor includes a second fixed bed, on which a second catalyst is packed; a second reactant can flow through the second catalyst on the second fixed bed to carry out a hydrogenation reaction; the reaction liquid circulation pump is used to return at least a portion of the reaction liquid obtained after the hydrogenation reaction to the high-pressure hydrogenation reactor and allow it to flow through the second catalyst on the second fixed bed.

[0006] The second aspect of this disclosure provides a method for preparing CDOL, the technical solution of which is as follows: A method for preparing CDOL, using the CDOL preparation apparatus described above, includes the following steps: The second reactant is fed into the high-pressure hydrogenation reactor and flows through the second catalyst on the second fixed bed to carry out a hydrogenation reaction, thereby obtaining the reaction liquid; wherein, the second reactant includes a starting reactant, hydrogen gas and a solvent, and the starting reactant includes at least one of EPO and ECDA; At least a portion of the reaction solution is circulated into the high-pressure hydrogenation reactor via the reaction solution circulation pump and flows through the second catalyst on the second fixed bed.

[0007] The third aspect of this disclosure provides a method for preparing CDOL, the technical solution of which is as follows: A method for preparing CDOL, using the CDOL preparation apparatus described above, includes the following steps: The first reactant is fed into the pre-hydrogenation reactor and flows through the first catalyst on the first fixed bed to carry out the pre-hydrogenation reaction, thereby obtaining the pre-hydrogenation reaction liquid; wherein, the first reactant includes EPO and first hydrogen gas; The second reactant is fed into the high-pressure hydrogenation reactor and flows through the second catalyst on the second fixed bed to carry out a hydrogenation reaction, thereby obtaining the reaction solution; wherein, the second reactant includes the pre-hydrogenated reaction solution; At least a portion of the reaction solution is circulated into the high-pressure hydrogenation reactor via the reaction solution circulation pump and flows through the second catalyst on the second fixed bed.

[0008] Compared with traditional solutions, this disclosure has the following advantages: The applicant analyzed why the reactor experienced intermittent temperature and pressure spikes after adding small molecule alcohols and concluded that this was related to the occasional dry bed formation in the high-pressure hydrogenation reactor, causing severe exothermic side reactions of the small molecule alcohols adsorbed on the catalyst. Specifically, during the hydrogenation reaction in the high-pressure hydrogenation reactor, the liquid reactants and high-pressure hydrogen flow through the catalyst intermittently result in a dry bed situation. This means the liquid phase in the reactor cannot continuously cover the catalyst bed, leading to partial or complete exposure of the catalyst to the gas phase. In this situation, the small molecule alcohols adsorbed on the catalyst undergo severe exothermic side reactions. Combined with the highly exothermic epoxidation ring-opening reaction, this easily causes temperature and pressure spikes in the reactor. To solve this problem, this disclosure includes a reaction liquid circulation pump, which removes the reaction liquid generated at the bottom of the high-pressure hydrogenation reactor and returns it to the reactor. This removes some of the reaction heat, dilutes the concentration of the reactants to control the temperature rise, and most importantly, the reaction liquid flows through the catalyst, preventing the catalyst bed from drying out, reducing the risk of severe exothermic side reactions of the small molecule alcohols adsorbed on the catalyst, improving the reactor's temperature and pressure spikes, and significantly enhancing system safety. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments and to more completely understand this disclosure and its beneficial effects, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the CDOL preparation apparatus in Example 1; Figure 2 This is a schematic diagram of the CDOL preparation apparatus in Example 2.

[0011] Figure label: 11: High-pressure hydrogenation reactor; 111: First storage zone; 112: Second storage zone; 113: First baffle; 12: Reaction liquid circulation pump; 13: Gas phase cooler; 14: High-pressure buffer tank; 141: Third storage zone; 142: Fourth storage zone; 143: Second baffle; 15: Circulating hydrogen compressor; 16: Shut-off valve; 161: First shut-off valve; 162: Second shut-off valve; 17: Recovered solvent circulation pump; 18: Pre-hydrogenation reactor; 19: First high-pressure feed pump; 20: First low-pressure buffer tank; 21: Second high-pressure feed pump; 22: Second low-pressure buffer tank. Detailed Implementation

[0012] The present disclosure will be further described in detail below with reference to specific embodiments. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure.

[0013] Unless otherwise defined, all technical and scientific terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure.

[0014] Regarding the issue of reactor overheating and overpressure occurring intermittently after the addition of small molecule alcohols during the hydrogenation reaction to prepare CDOL, the applicant believes that this problem is related to the occasional occurrence of a dry bed in the high-pressure hydrogenation reactor, causing severe exothermic side reactions of the small molecule alcohols adsorbed on the catalyst. Specifically, during the hydrogenation reaction in the high-pressure hydrogenation reactor, the liquid reactants and high-pressure hydrogen gas flow through the catalyst, sometimes resulting in a dry bed situation. This means that the liquid phase in the high-pressure hydrogenation reactor cannot continuously cover the catalyst bed, causing some or all of the catalyst to be directly exposed to the gas phase. In this situation, the small molecule alcohols adsorbed on the catalyst undergo severe exothermic side reactions. Combined with the strongly exothermic epoxidation ring-opening reaction, this easily leads to reactor overheating and overpressure problems.

[0015] Based on the above analysis, in order to solve the aforementioned problems, the first aspect of this disclosure provides an apparatus for preparing CDOL. In Example 1, please refer to... Figure 1 The CDOL preparation apparatus includes a high-pressure hydrogenation reactor 11 and a reaction liquid circulation pump 12. The high-pressure hydrogenation reactor 11 includes a second fixed bed, on which a second catalyst is packed. The second reaction feedstock can flow through the second catalyst on the second fixed bed to carry out the hydrogenation reaction. The reaction liquid circulation pump 12 is used to send at least a portion of the reaction liquid obtained after the hydrogenation reaction back into the high-pressure hydrogenation reactor 11 and make it flow through the second catalyst on the second fixed bed.

[0016] In Example 1, a reaction liquid circulation pump 12 is provided, which can remove the reaction liquid generated at the bottom of the high-pressure hydrogenation reactor 11 and send it back to the high-pressure hydrogenation reactor 11 to flow through the catalyst. On the one hand, it removes some of the reaction heat; on the other hand, it dilutes the concentration of the reaction raw materials and controls the temperature rise. Most importantly, the reaction liquid flowing through the catalyst can avoid the catalyst bed from drying out, reduce the risk of violent exothermic side reactions of small molecule alcohols adsorbed by the catalyst, improve the problem of reactor overheating and overpressure, and greatly improve the safety of the system.

[0017] In Example 1, the second catalyst in the high-pressure hydrogenation reactor is a heterogeneous solid catalyst. The reactor is a fixed-bed adiabatic reactor. The reaction operation is a trickle bed. The reaction liquid circulation pump can be equipped with an emergency power supply and a diesel generator, so that power can still be supplied under abnormal operating conditions.

[0018] Optionally, the preparation apparatus also includes a cooler for cooling the reaction liquid or second reaction feedstock returned to the high-pressure hydrogenation reactor. The cooler is air-cooled, retaining some cooling capacity even during power outages. Optionally, the cooler can cool the temperature to 30-50°C.

[0019] Optionally, the high-pressure hydrogenation reactor 11 is provided with a reaction liquid containing chamber, which includes a first storage zone 111 and a second storage zone 112. The reaction liquid can first flow into the first storage zone 111, and automatically enter the second storage zone 112 after accumulating to a set amount. The reaction liquid in the first storage zone 111 is removed by the reaction liquid circulation pump 12 and sent back into the high-pressure hydrogenation reactor 11, flowing through the second catalyst on the second fixed bed. The reaction liquid in the second storage zone 112 flows out of the high-pressure hydrogenation reactor 11. The reliability of its own liquid phase circulation is ensured through the circulation of the reaction liquid in the first storage zone 111. The reaction liquid flowing out of the second storage zone 112 can enter the downstream solvent and CDOL product separation system after depressurization.

[0020] Optionally, the first liquid storage area 111 and the second liquid storage area 112 are formed by dividing the first partition 113 so that the reaction liquid can automatically overflow into the second liquid storage area 112 after accumulating to a set liquid level.

[0021] In some embodiments, the reaction liquid containment chamber may be formed by the inner wall of the high-pressure hydrogenation reactor, with a first baffle placed on the bottom inner wall of the high-pressure hydrogenation reactor, dividing the reaction liquid containment chamber into a first liquid storage area and a second liquid storage area that are interconnected; in other embodiments, the high-pressure hydrogenation reactor has a built-in liquid collector that provides the reaction liquid containment chamber, and the liquid collector has a built-in first baffle that divides the reaction liquid containment chamber of the liquid collector into a first liquid storage area and a second liquid storage area that are interconnected.

[0022] Optionally, the preparation apparatus further includes a gas phase cooler 13 and a high-pressure buffer tank 14. The gas phase cooler 13 is connected to the high-pressure hydrogenation reactor 11 and is used to cool the gas phase flowing out of the high-pressure hydrogenation reactor 11. The high-pressure buffer tank 14 is connected to the gas phase cooler 13 and is used to collect the recovered solvent flowing out of the gas phase cooler 13. In the high-pressure hydrogenation reactor 11, the reaction is exothermic, the temperature rises, and the solvent vaporizes with the hydrogen, flowing out as a gas phase. It is condensed into a liquid recovered solvent by the gas phase cooler 13 and collected in the high-pressure buffer tank 14. The high-pressure buffer tank 14 collects the recovered solvent separately, which can reduce the solvent content in the downstream reaction liquid, reduce the cost of CDOL separation from solvent, reduce energy consumption, and further reduce the amount of dissolved hydrogen in the downstream reaction liquid due to its high CDOL concentration and low flow rate, thus reducing hydrogen consumption in the high-pressure hydrogenation reactor.

[0023] Optionally, the preparation apparatus also includes a circulating hydrogen compressor 15, which pressurizes the recovered hydrogen flowing from the gas phase cooler 13 and sends it back to the high-pressure hydrogenation reactor 11. By setting up the gas phase cooler 13 and the circulating hydrogen compressor 15, hydrogen can be recycled, reducing hydrogen consumption in the high-pressure system and improving competitiveness. At the same time, the circulating hydrogen compressor 15 can also regulate the temperature of the recovered hydrogen while pressurizing it.

[0024] Optionally, the high-pressure buffer tank 14 includes a third liquid storage zone 141 and a fourth liquid storage zone 142. The recovered solvent can first flow into the third liquid storage zone 141 and automatically enter the fourth liquid storage zone 142 after the recovered solvent has accumulated to a set amount.

[0025] Optionally, the high-pressure buffer tank 14 has a built-in second partition 143, which divides the high-pressure buffer tank 14 into two interconnected storage zones: a third storage zone 141 and a fourth storage zone 142. This allows the recovered solvent to automatically overflow into the fourth storage zone 142 after accumulating to a set liquid level. The high-pressure buffer tank 14 can also serve as a safety tank. In the event of a runaway reaction and excessively high temperature, the recovered solvent in the third storage zone 141 of the high-pressure buffer tank 14 can be used as a quenching agent to reduce safety risks. The volume and partition arrangement of the high-pressure buffer tank 14 meet the requirements for quenching.

[0026] Optionally, at least one passage is provided between the high-pressure buffer tank 14 and the high-pressure hydrogenation reactor 11. This passage allows the recovered solvent from the third storage zone 141 to flow into the high-pressure hydrogenation reactor 11. Each passage is equipped with a shut-off valve 16. When the shut-off valve 16 is open, the corresponding passage is connected; when the shut-off valve 16 is closed, the corresponding passage is disconnected. The number of shut-off valves 16 depends on the number of passages, which in turn depends on the number of beds in the second fixed bed of the high-pressure hydrogenation reactor 11. Each second fixed bed can correspond to one passage, allowing the recovered solvent to rapidly flow through the second fixed bed for rapid cooling. In Example 1, there are two passages, corresponding to two shut-off valves: a first shut-off valve 161 and a second shut-off valve 162. In case of an anomaly such as a power outage, if the reaction liquid circulation pump 12 stops operating, the shut-off valve 16 is opened to connect the passages. The recovered solvent from the third storage zone 141 is used to wet the catalyst for cooling, preventing bed overheating and improving the safety of the hydrogenation reaction system. Simultaneously, the gas phase cooler 13 naturally acts as an equalizing line, ensuring the reliability of the recovered solvent injection.

[0027] Optionally, the preparation apparatus also includes a solvent recovery circulation pump 17, through which the recovered solvent in the fourth storage zone 142 can be returned to the high-pressure hydrogenation reactor 11 and flow through the second catalyst on the second fixed bed. This increases the solvent concentration in the high-pressure hydrogenation reactor 11 and controls the adiabatic temperature rise of the reactor 11. Furthermore, when the solvent supply is abnormally interrupted, the circulation of the recovered solvent can reduce the system concentration, preventing high concentrations in the reactor from affecting safety. Understandably, the solvent recovery circulation pump 17 can also pressurize the recovered solvent.

[0028] By integrating the gas phase cooler 13, high-pressure buffer tank 14, circulating hydrogen compressor 15, shut-off valve 16, and solvent recovery circulation pump 17, the inherent safety of the preparation device can be significantly improved. This facilitates a safer CDOL preparation process, fully utilizes process materials, reduces waste gas, lowers energy consumption, and saves operating costs.

[0029] In this disclosure, the second reaction raw material may include a starting reactant, hydrogen, and a solvent, wherein the starting reactant includes at least one of EPO and ECDA; it may also include a pre-hydrogenated reaction liquid, wherein the pre-hydrogenated reaction liquid is obtained by pre-hydrogenating the first reaction raw material, the first reaction raw material including EPO. Depending on the second reaction raw material, this disclosure provides a corresponding preparation apparatus.

[0030] In some embodiments, the second reactant includes a pre-hydrogenated reaction solution. For example, in Example 1, please continue to refer to... Figure 1 The preparation apparatus further includes a pre-hydrogenation reactor 18, which includes a first fixed bed filled with a first catalyst. The first reactant can flow through the first catalyst on the first fixed bed to undergo a pre-hydrogenation reaction, yielding a pre-hydrogenated reaction liquid. Optionally, the pre-hydrogenation reactor can be a bed reactor, a tubular reactor, or a batch reactor. In Example 1, the first reactant includes EPO and hydrogen, which are respectively introduced into the pre-hydrogenation reactor 18. The tail gas generated by the pre-hydrogenation reaction can be discharged from the bottom of the pre-hydrogenation reactor 18. In Example 1, the preparation apparatus also includes a first high-pressure feed pump 19, which is used to feed a second reactant into the high-pressure hydrogenation reactor 11, wherein the second reactant includes the pre-hydrogenated reaction liquid. Understandably, the second reactant is pressurized by the first high-pressure feed pump. Optionally, the preparation apparatus also includes a first low-pressure buffer tank 20. In some embodiments, the first low-pressure buffer tank is used to feed a portion of the second reaction material to the first high-pressure feed pump; in other embodiments, the first low-pressure buffer tank is used to feed a portion of the first reaction material to the pre-hydrogenation reactor. Optionally, the first low-pressure buffer tank 20 is used to store solvent, and both the portion of the second reaction material and the portion of the first reaction material being fed are solvents. In Example 1, the second reaction material includes solvent in addition to the pre-hydrogenation reaction liquid. The first low-pressure buffer tank 20 is used to feed solvent to the first high-pressure feed pump 19, and the solvent and the pre-hydrogenation reaction liquid flow concurrently as the second reaction material, which is fed into the high-pressure hydrogenation reactor 11 by the first high-pressure feed pump 19.

[0031] In other embodiments, the second reactant includes a starting reactant, hydrogen, and a solvent, wherein the starting reactant includes at least one of EPO and ECDA. The preparation apparatus also includes a second high-pressure feed pump for feeding the second reactant into the high-pressure hydrogenation reactor. Understandably, the second high-pressure feed pump pressurizes the second reactant. Optionally, the preparation apparatus also includes a second low-pressure buffer tank for supplying a portion of the second reactant to the second high-pressure feed pump. For example, see [link to relevant documentation]. Figure 2In Example 2, the CDOL preparation apparatus includes a high-pressure hydrogenation reactor 11 and a reaction liquid circulation pump 12. The high-pressure hydrogenation reactor 11 includes a second fixed bed, on which a second catalyst is packed. The second reactant can flow through the second catalyst on the second fixed bed to undergo a hydrogenation reaction. The reaction liquid circulation pump 12 is used to return at least a portion of the reaction liquid obtained after the hydrogenation reaction to the high-pressure hydrogenation reactor 11 and allow it to flow through the second catalyst on the second fixed bed. The high-pressure hydrogenation reactor 11 is provided with a reaction liquid containing chamber, which includes a first storage zone 111 and a second storage zone 112. The reaction liquid can first flow into the first storage zone 111 and automatically enter the second storage zone 112 after accumulating to a set amount. The reaction liquid in the first storage zone 111 is removed by the reaction liquid circulation pump 12 and returned to the high-pressure hydrogenation reactor 11, flowing through the second catalyst on the second fixed bed. The reaction liquid in the second storage zone 112 flows out of the high-pressure hydrogenation reactor 11. The reaction liquid flowing out of the second storage zone 112 can enter the downstream solvent and CDOL product separation system after depressurization. The first storage zone 111 and the second storage zone 112 are separated by a first partition 113 so that the reaction liquid automatically overflows into the second storage zone 112 after accumulating to a set liquid level. The preparation apparatus also includes a vapor phase cooler 13 and a high-pressure buffer tank 14; the vapor phase cooler 13 is connected to the high-pressure hydrogenation reactor 11 and is used to cool the vapor phase flowing out of the high-pressure hydrogenation reactor 11; the high-pressure buffer tank 14 is connected to the vapor phase cooler 13 and is used to collect the recovered solvent flowing out of the vapor phase cooler 13. The preparation apparatus also includes a circulating hydrogen compressor 15, which is used to pressurize the recovered hydrogen flowing out of the vapor phase cooler 13 and send it back to the high-pressure hydrogenation reactor 11. The high-pressure buffer tank 14 includes a third storage zone 141 and a fourth storage zone 142. The recovered solvent can first flow into the third storage zone 141 and automatically enter the fourth storage zone 142 after accumulating to a set amount. The high-pressure buffer tank 14 has a built-in second partition 143, which divides the high-pressure buffer tank 14 into a third storage zone 141 and a fourth storage zone 142 that are interconnected, so that the recovered solvent automatically overflows into the fourth storage zone 142 after accumulating to a set liquid level. At least one passage is provided between the high-pressure buffer tank 14 and the high-pressure hydrogenation reactor 11, for the recovered solvent in the third storage zone 141 to flow into the high-pressure hydrogenation reactor 11. Each passage is equipped with a shut-off valve 16. When the shut-off valve 16 is open, the corresponding passage is connected; when the shut-off valve 16 is closed, the corresponding passage is disconnected. The number of shut-off valves 16 depends on the number of passages, which in turn depends on the number of second fixed beds in the high-pressure hydrogenation reactor 11. Each second fixed bed can correspond to one passage, so that the recovered solvent can quickly flow through the second fixed bed for rapid cooling. In Example 2, there are two passages, corresponding to two shut-off valves: a first shut-off valve 161 and a second shut-off valve 162.In the event of an anomaly such as a power outage, if the reaction liquid circulation pump 12 stops operating, the shut-off valve 16 is opened to connect the passage, and the catalyst is wetted with the recovered solvent from the third storage zone 141 to cool it down, preventing bed overheating and improving the safety of the hydrogenation reaction system. Simultaneously, the gas phase cooler 13 naturally acts as an equalizing line, ensuring the reliability of the recovered solvent injection. The preparation apparatus also includes a recovered solvent circulation pump 17, through which the recovered solvent from the fourth storage zone 142 can be returned to the high-pressure hydrogenation reactor 11 and flow through the second catalyst on the second fixed bed. The preparation apparatus also includes a second high-pressure feed pump 21, which is used to feed the second reaction raw material into the high-pressure hydrogenation reactor 11. The preparation apparatus also includes a second low-pressure buffer tank 22, which is used to supply a portion of the second reaction raw material to the second high-pressure feed pump 21.

[0032] In traditional reactors, the mother liquor containing CDOL produced during the hydrogenation reaction is collected directly from the bottom of the high-pressure hydrogenation reactor to obtain CDOL. In this embodiment, however, a reaction liquid circulation pump is used to return the reaction liquid from the high-pressure hydrogenation reactor to the catalyst bed, preventing the catalyst bed from drying out, ensuring catalyst bed wettability, reducing the risk of hydrogenation reaction, and decreasing the solvent content in the downstream reaction liquid. This lowers the cost of CDOL-solvent separation and also reduces hydrogen consumption in the high-pressure system. Through these reductions in material and energy consumption, the system achieves better economic efficiency.

[0033] The aforementioned CDOL preparation apparatus fully integrates various devices, reducing the number of components in the high-pressure hydrogenation system and improving on-site operational safety. It offers the following advantages: In summary, the positive effects of this disclosure are as follows: 1) By setting up a reaction liquid circulation pump, the reliability of the reaction liquid circulation in the high-pressure hydrogenation reactor is improved, avoiding a dry bed in the high-pressure hydrogenation reactor and reducing the risk of reaction runaway.

[0034] 2) The high-pressure buffer tank is also used as a quench agent storage tank, and gravity pressure equalization is used to avoid dry bed in the high-pressure hydrogenation reactor, thereby reducing the risk of reaction runaway.

[0035] 3) Set up a pre-hydrogenation reactor. By adding hydrogen in steps, most of the heat is released in the low-pressure system and the remaining heat is released in the high-pressure system. This separates the violent hydrogenation reaction from the harsh reaction conditions and reduces the risk of reaction runaway.

[0036] 4) By recycling solvents, the reliability of solvent sources is improved, the CDOL concentration of the downstream reaction liquid is increased, the energy consumption of the CDOL and solvent separation system is reduced, the dissolved hydrogen in the downstream reaction liquid is reduced, and material and energy consumption is reduced. This is a greener, safer, and more economical process.

[0037] A second aspect of this disclosure provides a method for preparing CDOL. In one embodiment, the method for preparing CDOL uses the CDOL preparation apparatus described above and includes the following steps: The second reactant is fed into the high-pressure hydrogenation reactor and flows through the second catalyst on the second fixed bed to carry out a hydrogenation reaction, thereby obtaining the reaction liquid; wherein, the second reactant includes a starting reactant, hydrogen gas and a solvent, and the starting reactant includes at least one of EPO and ECDA; At least a portion of the reaction solution is circulated into the high-pressure hydrogenation reactor via the reaction solution circulation pump and flows through the second catalyst on the second fixed bed.

[0038] In this embodiment, no pre-hydrogenation reaction is performed; the hydrogenation reaction is carried out directly in the high-pressure hydrogenation reactor.

[0039] Optionally, the second catalyst is selected from at least one of carbon-supported nickel catalysts, carbon-supported palladium catalysts, and nickel-aluminum alloy catalysts. For example, the second catalyst is a Raney catalyst, which has high reactivity. For example, the second catalyst can be a catalyst disclosed in CN107649149A, CN109225261A, CN106140195A, CN104607207A, and CN103977819A. The solvent is adsorbed on the second catalyst, which has high activity. When the system experiences a power outage or other abnormal operating conditions that cause the catalyst bed to dry out, the solvent will undergo a violent exothermic side reaction, leading to overheating of the entire system. This embodiment prevents the catalyst bed from drying out by circulating at least a portion of the reaction liquid, which helps reduce the risk of system overheating and achieves intrinsic safety. Understandably, the reaction liquid can also be degassed.

[0040] The solvent is a small molecule alcohol. The hydrogenation reaction to prepare CDOL involves high pressure, a large hydrogen circulation volume, harsh reaction conditions, and the release of a significant amount of heat. By using a solvent to dilute the reactants, the safety and controllability of the hydrogenation reaction can be effectively improved, as well as the selectivity of the reaction and the economic competitiveness of the process. Furthermore, the solvent can also increase the solubility of hydrogen in the liquid phase and enhance mass transfer in the hydrogenation reaction. Optionally, the solvent is selected from at least one of methanol, ethanol, and isopropanol.

[0041] Optionally, the mass of the solvent is 1 to 10 times the mass of the starting reactant. For example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times.

[0042] Optionally, the molar ratio of hydrogen to the starting reactant is (10~60):1. For example, the molar ratios are 10:1, 20:1, 30:1, 40:1, 50:1, and 60:1.

[0043] Optionally, the mass hourly space velocity (MHSV) of the second reactant is 0.03 to 0.25 g / gcat / h. For example, MHSVs of 0.03 g / gcat / h, 0.1 g / gcat / h, 0.15 g / gcat / h, 0.2 g / gcat / h, and 0.25 g / gcat / h are used.

[0044] Optionally, the hydrogenation reaction is carried out at a temperature of 50 to 170°C. For example, temperatures of 50°C, 80°C, 100°C, 150°C, and 170°C.

[0045] Optionally, the ambient pressure of the hydrogenation reaction is 6~18 MPaG. For example, the ambient pressure is 6 MPaG, 10 MPaG, 15 MPaG, or 18 MPaG.

[0046] This disclosure provides a method for preparing CDOL in a third aspect. In one embodiment, the method for preparing CDOL uses the CDOL preparation apparatus described above and includes the following steps: The first reactant is fed into the pre-hydrogenation reactor and flows through the first catalyst on the first fixed bed to carry out the pre-hydrogenation reaction, thereby obtaining the pre-hydrogenation reaction liquid; wherein, the first reactant includes EPO and first hydrogen gas; The second reactant is fed into the high-pressure hydrogenation reactor and flows through the second catalyst on the second fixed bed to carry out a hydrogenation reaction, thereby obtaining the reaction solution; wherein, the second reactant includes the pre-hydrogenated reaction solution; At least a portion of the reaction solution is circulated into the high-pressure hydrogenation reactor via the reaction solution circulation pump and flows through the second catalyst on the second fixed bed.

[0047] In this embodiment, a pre-hydrogenation reaction is carried out in a pre-hydrogenation reactor before the hydrogenation reaction in the high-pressure hydrogenation reactor. The pre-hydrogenation reaction can hydrogenate the easily hydrogenated carbon-carbon double bonds in EPO. The process conditions of the pre-hydrogenation reaction are more moderate than those of the hydrogenation reaction. Through the pre-hydrogenation reaction, most of the heat of reaction can be removed under more moderate process conditions, improving the safety of the high-pressure hydrogenation reactor.

[0048] Optionally, the first catalyst is selected from at least one of supported nickel catalysts, cobalt catalysts, palladium catalysts, platinum catalysts, ruthenium catalysts, and rhodium catalysts; preferably, at least one of supported nickel catalysts, cobalt catalysts, palladium catalysts, and platinum catalysts.

[0049] Optionally, the first reaction feedstock further includes a first solvent. Optionally, the first solvent is a small molecule alcohol. By using the first solvent to dilute the reaction feedstock, the safety and controllability of the pre-hydrogenation reaction can be effectively improved, and the selectivity of the reaction can be enhanced, thereby increasing the economic competitiveness of the process. Furthermore, the solvent can also increase the solubility of hydrogen in the liquid phase, enhancing the mass transfer of the hydrogenation reaction. Optionally, the first solvent is selected from at least one of methanol, ethanol, and isopropanol.

[0050] Optionally, the mass of the first solvent is 1 to 10 times the mass of the EPO. For example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times. Preferably, it is 2 to 10 times.

[0051] The first hydrogen gas may be derived from recycled dissolved hydrogen or other low-pressure hydrogen. Optionally, the molar ratio of the first hydrogen gas to the EPO is (1~6):1. For example, the molar ratios are 1:1, 2:1, 3:1, 4:1, 5:1, and 6:1.

[0052] Optionally, the mass hourly space velocity (MHSV) of the EPO is 0.3 to 2.5 g / gcat / h. For example, the MHSV is 0.03 g / gcat / h, 0.1 g / gcat / h, 0.15 g / gcat / h, 0.2 g / gcat / h, or 0.25 g / gcat / h.

[0053] Optionally, the temperature of the pre-hydrogenation reaction is 40~80℃. For example, the temperature is 40℃, 50℃, 60℃, 70℃, or 80℃.

[0054] Optionally, the ambient pressure of the pre-hydrogenation reaction is 0.1~2 MPaG. For example, the ambient pressure is 0.1 MPaG, 1 MPaG, 1.5 MPaG, or 2 MPaG.

[0055] Optionally, the second catalyst is selected from at least one of carbon-supported nickel catalysts, carbon-supported palladium catalysts, and nickel-aluminum alloy catalysts. For example, the second catalyst is a Raney catalyst, which has high reactivity. For example, the second catalyst can be a catalyst disclosed in CN107649149A, CN109225261A, CN106140195A, CN104607207A, and CN103977819A. The solvent is adsorbed on the second catalyst, which has high activity. When the system experiences a power outage or other abnormal operating conditions that cause the catalyst bed to dry out, the solvent will undergo a violent exothermic side reaction, leading to overheating of the entire system. This embodiment prevents the catalyst bed from drying out by circulating at least a portion of the reaction liquid, which helps reduce the risk of system overheating and achieves intrinsic safety. Understandably, the reaction liquid can also be degassed.

[0056] Optionally, the second reaction feedstock further includes at least one of a second hydrogen gas and a second solvent.

[0057] The second solvent is a small molecule alcohol. By using a second solvent to dilute the reaction feedstock, the safety and controllability of the hydrogenation reaction can be effectively improved, as well as the selectivity of the reaction and the economic competitiveness of the process. Furthermore, the solvent can also increase the solubility of hydrogen in the liquid phase, enhancing mass transfer in the hydrogenation reaction. Optionally, the second solvent is selected from at least one of methanol, ethanol, and isopropanol.

[0058] Optionally, the mass of the second solvent is 0.5 to 1.5 times the mass of the pre-hydrogenated reaction solution. For example, 0.5 times, 1 time, or 1.5 times.

[0059] Optionally, the molar ratio of the second hydrogen gas to ECDA in the pre-hydrogenated reaction solution is (10~60):1. For example, the molar ratios are 10:1, 20:1, 30:1, 40:1, 50:1, and 60:1.

[0060] Optionally, the mass hourly space velocity (MHSV) of the pre-hydrogenated reaction solution and the second solvent is 0.03~0.25 g / gcat / h. For example, MHSVs of 0.03 g / gcat / h, 0.1 g / gcat / h, 0.15 g / gcat / h, 0.2 g / gcat / h, and 0.25 g / gcat / h are used.

[0061] Optionally, the hydrogenation reaction is carried out at a temperature of 50 to 170°C. For example, temperatures of 50°C, 80°C, 100°C, 150°C, and 170°C.

[0062] Optionally, the ambient pressure of the hydrogenation reaction is 6~18 MPaG. For example, the ambient pressure is 6 MPaG, 10 MPaG, 15 MPaG, or 18 MPaG.

[0063] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available; the instruments used are all commercially available unless otherwise specified; and the processes involved are conventionally selected by those skilled in the art unless otherwise specified.

[0064] Example 1 This embodiment provides an apparatus and method for preparing CDOL. The apparatus is described in [reference needed]. Figure 1 The preparation method is as follows: 1) EPO and hydrogen are introduced into the tubular pre-hydrogenation reactor 18 at a molar ratio of 1:1.5 to carry out the pre-hydrogenation reaction. The reaction temperature is 70℃, the reaction pressure is 0.5MPaG, the reaction catalyst is a noble metal ruthenium catalyst, and the EPO material space velocity is 0.8g / gcat / h to obtain the pre-hydrogenation reaction liquid. 2) The pre-hydrogenated reaction liquid and methanol solvent are added to the high-pressure hydrogenation reactor 11 in a 1:1 mass ratio. Hydrogen gas is added to the high-pressure hydrogenation reactor. The molar ratio of hydrogen gas to ECDA in the pre-hydrogenated reaction liquid is 60:1. The hydrogenation reaction is carried out at a reaction temperature of 160°C and a reaction pressure of 16 MPaG. The catalyst used is the catalyst in Example 1 of CN107649149A. The space velocity of the pre-hydrogenated reaction liquid and methanol solvent is 0.08 g / gcat / h. The resulting reaction liquid first flows into the first storage zone 111. The reaction liquid in the first storage zone 111 is pressurized and circulated by the reaction liquid circulation pump 12, cooled by the cooler, and then sent back to the high-pressure hydrogenation reactor 11, flowing through the catalyst. Simultaneously, the gas phase in the high-pressure hydrogenation reactor 11 is cooled by the gas phase cooler 13, and the recovered hydrogen is sent back to the high-pressure hydrogenation reactor 11 via the circulating hydrogen compressor 15. The recovered solvent is condensed into the high-pressure buffer tank 14. The recovered solvent in the fourth storage zone of the high-pressure buffer tank 14 is pressurized and sent back to the high-pressure hydrogenation reactor 11 by the recovered solvent circulation pump 17. The reaction liquid overflowing into the second storage zone 112 is depressurized and sent downstream.

[0065] After 1 hour of reaction, the molar yield of EPO to CDOL reached 99%. The dissolved hydrogen in the downstream reaction solution was 90 Nm³. 3 The CDOL concentration was 50 wt% per hour, and the downstream solvent recovery system consumed 3 MW of energy. Meanwhile, no overheating or overpressure issues occurred in the high-pressure hydrogenation reactor 11.

[0066] Example 2 This embodiment provides an apparatus and method for preparing CDOL. The apparatus is described in [reference needed]. Figure 2 The preparation method is as follows: 1) EPO and hydrogen are introduced into the high-pressure hydrogenation reactor 11 at a molar ratio of 1:60. Methanol solvent is pumped into the high-pressure hydrogenation reactor 11 through the second high-pressure feed pump 21. The space velocity of methanol solvent is 0.08 g / gcat / h, and the space velocity of EPO is 0.8 g / gcat / h. The hydrogenation reaction is carried out in the high-pressure hydrogenation reactor 11 at a reaction temperature of 160°C and a reaction pressure of 16 MPaG. The catalyst used is the catalyst from Example 1 of CN107649149A. The resulting reaction liquid first flows into the first storage zone 111. The reaction liquid in the first storage zone 111 is pressurized and circulated by the reaction liquid circulation pump 12, cooled by the cooler, and then sent back to the high-pressure hydrogenation reactor 11, flowing through the catalyst. Simultaneously, the gas phase in the high-pressure hydrogenation reactor 11 is cooled by the gas phase cooler 13, and the recovered hydrogen is sent back to the high-pressure hydrogenation reactor 11 via the circulating hydrogen compressor 15. The recovered solvent is condensed into the high-pressure buffer tank 14. The recovered solvent in the fourth storage zone of the high-pressure buffer tank 14 is pressurized and sent back to the high-pressure hydrogenation reactor 11 by the recovered solvent circulation pump 17. The reaction liquid overflowing into the second storage zone 112 is depressurized and sent downstream.

[0067] After 1 hour of reaction, the molar yield of EPO to CDOL reached 98%. The dissolved hydrogen in the downstream reaction solution was 90 Nm³. 3 The CDOL concentration was 50 wt% per hour, and the downstream solvent recovery system consumed 3 MW of energy. Meanwhile, no overheating or overpressure issues occurred in the high-pressure hydrogenation reactor 11.

[0068] Comparative Example 1 This comparative example provides a CDOL preparation apparatus and preparation method, which are basically the same as those in Example 1. The main difference is that the preparation apparatus does not include the reaction liquid circulation pump 12, and no baffle is set in the high-pressure hydrogenation reactor, so all the reaction liquid is sent downstream.

[0069] After 1 hour of reaction, the molar yield of EPO to CDOL reaches 98%. The dissolved hydrogen gas in the downstream reaction solution is 300 Nm³. 3 The CDOL concentration is 30wt% per hour, and the downstream solvent recovery system consumes 9MW of energy. Meanwhile, a power outage in the high-pressure hydrogenation reactor 11 can cause overheating and overpressure issues.

[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The embodiments described above are merely illustrative of several implementation methods, and while their descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept, and these all fall within the scope of protection.

Claims

1. An apparatus for preparing cyclododecanol, characterized in that, It includes a high-pressure hydrogenation reactor (11) and a reaction liquid circulation pump (12); the high-pressure hydrogenation reactor (11) includes a second fixed bed, the second fixed bed being filled with a second catalyst; the second reaction feedstock can flow through the second catalyst on the second fixed bed to carry out the hydrogenation reaction; the reaction liquid circulation pump (12) is used to send at least a portion of the reaction liquid obtained after the hydrogenation reaction back into the high-pressure hydrogenation reactor (11) and make it flow through the second catalyst on the second fixed bed.

2. The apparatus for preparing cyclododecyl alcohol according to claim 1, characterized in that, The high-pressure hydrogenation reactor (11) is provided with a reaction liquid containing chamber, which includes a first storage zone (111) and a second storage zone (112). The reaction liquid can first flow into the first storage zone (111) and automatically enter the second storage zone (112) after the reaction liquid accumulates to a set amount. The reaction liquid in the first storage zone (111) is removed by the reaction liquid circulation pump (12) and sent back to the high-pressure hydrogenation reactor (11) and flows through the second catalyst on the second fixed bed. The reaction liquid in the second storage zone (112) flows out of the high-pressure hydrogenation reactor (11).

3. The apparatus for preparing cyclododecyl alcohol according to any one of claims 1 to 2, characterized in that, The preparation apparatus further includes a gas phase cooler (13) and a high-pressure buffer tank (14); the gas phase cooler (13) is connected to the high-pressure hydrogenation reactor (11) and is used to cool the gas phase flowing out of the high-pressure hydrogenation reactor (11); the high-pressure buffer tank (14) is connected to the gas phase cooler (13) and is used to collect the recovered solvent flowing out of the gas phase cooler (13).

4. The apparatus for preparing cyclododecyl alcohol according to claim 3, characterized in that, The high-pressure buffer tank (14) includes a third liquid storage area (141) and a fourth liquid storage area (142). The recovered solvent can first flow into the third liquid storage area (141) and automatically enter the fourth liquid storage area (142) after the recovered solvent accumulates to a set amount.

5. The apparatus for preparing cyclododecyl alcohol according to claim 4, characterized in that, Includes at least one of the following features: a) At least one passage is provided between the high-pressure buffer tank (14) and the high-pressure hydrogenation reactor (11), the passage being used for the recovered solvent in the third storage zone (141) to flow into the high-pressure hydrogenation reactor (11); each passage is equipped with a shut-off valve (16), the passage is connected when the shut-off valve (16) is open, and disconnected when the shut-off valve (16) is closed; b) The preparation apparatus further includes a solvent recovery circulation pump (17), through which the recovered solvent in the fourth storage zone (142) can be returned to the high-pressure hydrogenation reactor (11) and flow through the second catalyst on the second fixed bed.

6. The apparatus for preparing cyclododecyl alcohol according to any one of claims 1 to 2, 4 to 5, characterized in that, The preparation apparatus further includes a second high-pressure feed pump (21), which is used to feed the second reaction raw material into the high-pressure hydrogenation reactor (11).

7. The apparatus for preparing cyclododecyl alcohol according to any one of claims 1 to 2, 4 to 5, characterized in that, The preparation apparatus further includes a pre-hydrogenation reactor (18), which includes a first fixed bed and is filled with a first catalyst; the first reaction raw material can flow through the first catalyst on the first fixed bed to carry out a pre-hydrogenation reaction to obtain a pre-hydrogenation reaction liquid.

8. The apparatus for preparing cyclododecyl alcohol according to claim 7, characterized in that, The preparation apparatus further includes a first high-pressure feed pump (19), which is used to feed the second reaction raw material into the high-pressure hydrogenation reactor (11), wherein the second reaction raw material includes the pre-hydrogenated reaction liquid.

9. A method for preparing cyclododecanol, characterized in that, The apparatus for preparing cyclododecyl alcohol according to any one of claims 1 to 6 comprises the following steps: The second reactant is fed into the high-pressure hydrogenation reactor (11) and flows through the second catalyst on the second fixed bed to carry out a hydrogenation reaction to obtain the reaction liquid; wherein the second reactant includes a starting reactant, hydrogen and a solvent, and the starting reactant includes at least one of 9,10-epoxy-1,5-cyclododecadiene and epoxycyclododecane; At least a portion of the reaction solution is circulated into the high-pressure hydrogenation reactor (11) via the reaction solution circulation pump (12) and flows through the second catalyst on the second fixed bed.

10. A method for preparing cyclododecanol, characterized in that, The apparatus for preparing cyclododecyl alcohol according to any one of claims 7 to 8 comprises the following steps: The first reactant is fed into the pre-hydrogenation reactor (18) and flows through the first catalyst on the first fixed bed to carry out the pre-hydrogenation reaction to obtain the pre-hydrogenation reaction liquid; wherein, the first reactant includes 9,10-epoxy-1,5-cyclododecadiene and first hydrogen gas; The second reactant is fed into the high-pressure hydrogenation reactor (11) and flows through the second catalyst on the second fixed bed to carry out a hydrogenation reaction, thereby obtaining the reaction liquid; wherein, the second reactant includes the pre-hydrogenated reaction liquid; At least a portion of the reaction solution is circulated into the high-pressure hydrogenation reactor (11) via the reaction solution circulation pump (12) and flows through the second catalyst on the second fixed bed.

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