Preparation method of piperidine and trickle reaction apparatus
By combining a trickle reactor and a ruthenium-carbon catalyst, the problems of low conversion rate and low purity in traditional piperidine production have been solved, achieving high-purity piperidine production at low temperature and high efficiency. Furthermore, the catalyst can be reused, reducing production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- MOJIA (SHANGHAI) BIOTECH CO LTD
- Filing Date
- 2023-06-20
- Publication Date
- 2026-05-26
AI Technical Summary
Traditional piperidine production methods involve high reaction temperatures, low conversion rates, and low product purity, making further purification through distillation difficult and resulting in the product containing a large amount of pyridine, the raw material.
A trickle-flow reaction apparatus is used. Liquid pentanediamine is added to the reaction vessel through the feed pipe and vaporized into gaseous pentanediamine, which reacts with a ruthenium-carbon catalyst at 160℃~200℃. Unreacted pentanediamine and piperidine are separated by a condenser and a condenser. The catalyst can be reactivated by solvent washing.
High conversion and high purity piperidine were achieved at lower temperatures, with fewer byproducts, easy product purification, and reusable catalysts, reducing production costs.
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Figure CN116768786B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of compound preparation technology, and in particular to a method for preparing piperidine and a trickle reaction apparatus. Background Technology
[0002] Piperidine, also known as hexahydropyridine or azacyclic cyclohexane, is a cyclic aliphatic secondary amine. Piperidine is a crucial intermediate in the fine chemical industry, widely used in the manufacture of local anesthetics, analgesics, bactericides, wetting agents, and curing agents for epoxy resins and rubber vulcanization accelerators. Traditional piperidine production methods primarily involve the hydrogenation of pyridine, often using Raney nickel catalysts in an autoclave at temperatures above 200°C and pressures approaching 7 MPa under heating and hydrogen purging. This method may result in incomplete hydrogenation, leading to the presence of a certain amount of pyridine in the product, which is difficult to further purify through distillation, resulting in a low conversion rate for piperidine production. Summary of the Invention
[0003] Therefore, it is necessary to provide a method for preparing piperidine and a trickle-flow reaction apparatus for carrying out the method. This method for preparing piperidine involves a low reaction temperature, high conversion rate, and high product purity.
[0004] In a first aspect, this application provides a method for preparing piperidine, using a trickle-type reaction apparatus. The trickle-type reaction apparatus includes a reaction vessel with an opening at the top, a feed pipe inserted into the reaction vessel, a top-closed collection vessel fitted around the outside of the reactor, and a heating assembly for heating the reaction vessel. The temperature of the reaction vessel is 160℃~200℃. A catalyst is fixed inside the reaction vessel, with the catalyst 1cm~2cm below the bottom surface of the reaction vessel. The outlet end of the feed pipe is lower than the fixed position of the catalyst.
[0005] Liquid pentanediamine is added to the reaction vessel through the feed pipe;
[0006] The liquid pentanediamine is vaporized using the heating assembly to obtain gaseous pentanediamine.
[0007] The gaseous pentanediamine comes into contact with and reacts with the catalyst.
[0008] In some embodiments, the reaction vessel is vertically arranged; a condensation section is provided on the side of the reaction vessel near the opening;
[0009] After the gaseous pentanediamine contacts and reacts with the ruthenium-carbon catalyst, the unreacted gaseous pentanediamine is condensed by the condensation section, thereby separating the unreacted gaseous pentanediamine from the gaseous piperidine obtained from the reaction.
[0010] In some embodiments, a condensation jacket is provided around the condensation section, and the condensation temperature is 120°C to 150°C.
[0011] In some embodiments, the trickle reaction apparatus further includes a condenser, the feed end of which is connected to the collection container;
[0012] The process further includes condensing the unreacted gaseous pentanediamine through the condenser, and then condensing the gaseous piperidine through the condenser.
[0013] In some embodiments, the drip-type reaction device further includes an air inlet pipe inserted into the collection container, with the air outlet end of the air inlet pipe close to the top of the collection container;
[0014] After the unreacted gaseous pentanediamine is condensed by the condenser and before the gaseous piperidine is condensed by the condenser, a carrier gas is introduced from the inlet pipe to blow the prepared gaseous piperidine from the collection container into the condenser.
[0015] In some embodiments, the flow rate of the carrier gas is 20 mL / min to 60 mL / min.
[0016] In some embodiments, the carrier gas includes at least one of nitrogen, argon, and helium.
[0017] In some embodiments, the flow rate of the liquid pentanediamine is 0.1 mL / min to 1 mL / min.
[0018] In some embodiments, the catalyst is a ruthenium-carbon catalyst, wherein the ruthenium content in the ruthenium-carbon catalyst is 2% by mass.
[0019] In some embodiments, the mass ratio of the catalyst to the flow rate of the liquid pentanediamine is 40 g: 1 mL / min to 120 g: 0.1 mL / min.
[0020] In some embodiments, the bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the reaction vessel, and the liquid pentanediamine is vaporized at the bottom of the reaction vessel. After the reaction is completed, the movable bottom valve is opened through the movable support rod, and the ruthenium-carbon catalyst is eluted with dichloromethane solvent.
[0021] Secondly, this application provides a trickle-type reaction device, comprising: a reaction container with an opening at the top, a feed pipe inserted into the reaction container, a top-closed collection container sleeved on the outside of the reactor, and a heating assembly for heating the reaction container. A catalyst is fixed inside the reaction container, the catalyst is 1 cm to 2 cm away from the bottom surface of the reaction container, and the outlet end of the feed pipe is lower than the fixed position of the catalyst.
[0022] In some embodiments, the reaction vessel is vertically arranged; a condensation section is provided on the side of the reaction vessel near the opening;
[0023] The trickle-type reaction device also includes a condenser, the feed end of which is connected to the collection container;
[0024] The drip-type reaction device also includes an air inlet pipe inserted into the collection container, with the air outlet end of the air inlet pipe close to the top of the collection container;
[0025] The bottom of the reaction vessel includes a movable support rod with a movable bottom valve.
[0026] The above-described method for preparing piperidine uses a trickle-flow reactor. Liquid pentanediamine is added to the bottom of the reaction vessel and vaporized at 160°C–200°C to form gaseous pentanediamine. The gaseous pentanediamine then rises and reacts with a ruthenium-carbon catalyst at 160°C–200°C to prepare piperidine. This method involves a relatively low reaction temperature, near the vaporization temperature of pentanediamine, resulting in fewer byproducts and easier purification of the product. Furthermore, the large contact area and long residence time between the gaseous pentanediamine and the catalyst allow for a more complete reaction and a higher piperidine conversion rate. A condenser at the top of the reaction vessel condenses unconverted gaseous pentanediamine and high-boiling-point byproducts, separating them from the gaseous piperidine product to obtain a high-purity crude piperidine product. After continuous operation for a period of time, the catalyst activity decreases. This can be restored by opening the movable bottom valve and rinsing the catalyst with solvent from the top, thereby reducing production costs. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the structure of a trickle-type reaction apparatus used in a method for preparing piperidine according to an embodiment of this application. Detailed Implementation
[0028] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.
[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0030] One embodiment of this application provides a method for preparing piperidine using a trickle-type reaction apparatus. The trickle-type reaction apparatus includes a reaction vessel with an opening at the top, a feed pipe inserted into the reaction vessel, a top-closed collection vessel fitted outside the reactor, and a heating assembly for heating the reaction vessel. The temperature of the reaction vessel is 160°C to 200°C. A ruthenium-carbon catalyst is fixed inside the reaction vessel, with the catalyst 1 cm to 2 cm from the bottom of the reaction vessel. The outlet end of the feed pipe is lower than the fixed position of the catalyst. The preparation process includes: adding liquid pentanediamine into the reaction vessel through the feed pipe, vaporizing the liquid pentanediamine through the heating assembly to obtain gaseous pentanediamine, and then contacting and reacting the gaseous pentanediamine with the ruthenium-carbon catalyst.
[0031] The above-described method for preparing piperidine uses a trickle-flow reactor. Liquid pentanediamine is added to the reaction vessel and vaporized at 160°C–200°C to form gaseous pentanediamine. During its ascent, the gaseous pentanediamine reacts with a ruthenium-carbon catalyst at 160°C–200°C to prepare piperidine. This method has a relatively low reaction temperature range, near the vaporization temperature of pentanediamine, resulting in fewer byproducts and easier product purification. Furthermore, the contact between the gaseous pentanediamine and the catalyst provides a large contact area and a longer residence time, allowing for a more complete reaction. This method achieves a high conversion rate in piperidine preparation. The condenser at the top of the reactor condenses unconverted gaseous pentanediamine and high-boiling-point byproducts, separating them from the gaseous piperidine product to obtain a high-purity crude product. After continuous operation for a period of time, the catalyst activity decreases. This can be restored by opening the movable bottom valve and rinsing the catalyst with solvent from the top, thereby reducing production costs.
[0032] Optionally, the reaction temperature is 160℃, 162℃, 164℃, 166℃, 168℃, 170℃, 172℃, 174℃, 176℃, 178℃, 180℃, 182℃, 184℃, 186℃, 188℃, 190℃, 192℃, 194℃, 196℃, 198℃, or 200℃.
[0033] Optionally, the ruthenium-carbon catalyst features: ruthenium content of 2% by mass; mesh size: 4-8 mesh; specific surface area: 400 (m²) 2 / g); Average pore size (nm): 2.5nm~5.5nm; Impurities (m%): Fe, Cr, Ni, Cu, Ag, Mg, etc. ≤0.3; Particle strength (m%): ≥90. Support state: columnar mesoporous carbon: diameter 0.8mm, length 2-8mm; Pore volume (m 3 / g): 0.2~0.5; Pore size (nm): 2.5; Bulk density (g / cm³) 3 ): 0.44; Compressive strength (N): 85; Average particle size (μm): 50.
[0034] In some embodiments, a condenser is provided on the side of the reaction vessel near the opening; after the gaseous pentanediamine contacts and reacts with the ruthenium-carbon catalyst, the unreacted gaseous pentanediamine is condensed through the condenser, separating it from the gaseous piperidine obtained from the reaction. The condenser utilizes the different boiling points of pentanediamine and piperidine; by setting a suitable temperature, the gaseous pentanediamine and high-boiling-point byproducts are condensed and fall back to the bottom of the reactor. The pentanediamine is re-vaporized and reacts with the catalyst, while the lower boiling point of piperidine prevents it from being condensed through the condenser and is collected through the opening of the reaction vessel, achieving separation of pentanediamine and piperidine and resulting in higher purity of the collected piperidine. The condensed unreacted gaseous pentanediamine can be used to repeat the catalytic preparation process of piperidine, reducing the amount of gaseous pentanediamine mixed into the product and increasing the product yield through repeated reactions.
[0035] In some embodiments, the temperature of the condenser is 120°C to 150°C, achieved by providing a condenser jacket around the reaction vessel. Within this temperature range, unreacted gaseous pentanediamine can be condensed and piperidine preparation can be repeated without condensation of the product piperidine. This temperature range provides good separation of gaseous pentanediamine and gaseous piperidine. Optionally, the temperature of the condenser is 120°C, 121°C, 122°C, 123°C, 124°C, 125°C, 126°C, 127°C, 128°C, 129°C, 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C, 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C, or 150°C.
[0036] In some embodiments, the reaction vessel is vertically positioned. In a vertically positioned reaction vessel, after the liquid pentanediamine vaporizes, the liquid pentanediamine naturally rises and reacts with the catalyst, resulting in better contact. After the reaction is complete, the unconverted gaseous pentanediamine and / or high-boiling-point byproducts can naturally fall back to the bottom of the reaction vessel, allowing the pentanediamine to be repeatedly used in the preparation of piperidine, and resulting in a high-purity crude piperidine product.
[0037] In some embodiments, the catalyst is positioned 1-2 cm from the bottom of the reaction vessel, and the outlet end of the feed pipe is close to the bottom of the reaction vessel. When liquid pentanediamine is added to the bottom of the reaction vessel through the feed pipe, it vaporizes at the bottom and then rises to react with the catalyst. More complete vaporization and more thorough contact between the gaseous pentanediamine and the catalyst result in a better reaction effect.
[0038] In some embodiments, the trickle-flow reaction apparatus further includes a condenser, the feed end of which is connected to a collection container; after condensing unreacted gaseous pentanediamine through the condenser section, the apparatus further includes condensing gaseous piperidine through the condenser. During passage through the condenser section, the pentanediamine is condensed, and the gaseous piperidine and gaseous pentanediamine are separated and then enter the condenser to be condensed into liquid piperidine and collected, facilitating subsequent product purification.
[0039] In some embodiments, the trickle-type reaction apparatus further includes an inlet pipe inserted into the collection container, with the outlet end of the inlet pipe near the top of the collection container; after the unreacted gaseous pentanediamine is condensed by the condenser and before the gaseous piperidine is condensed by the condenser, a carrier gas is introduced through the inlet pipe to blow the prepared gaseous piperidine from the collection container into the condenser. By blowing the gaseous piperidine from the collection container into the condenser using a carrier gas, the condensation and collection rate of piperidine can be controlled.
[0040] In some embodiments, the carrier gas flow rate is 20 mL / min to 60 mL / min. Within this flow rate range, the residence time of gaseous pentanediamine in contact with the catalyst is longer, resulting in a more complete reaction. Optionally, the carrier gas flow rate is 20 mL / min, 22 mL / min, 24 mL / min, 26 mL / min, 28 mL / min, 30 mL / min, 32 mL / min, 34 mL / min, 36 mL / min, 38 mL / min, 40 mL / min, 42 mL / min, 44 mL / min, 46 mL / min, 48 mL / min, 50 mL / min, 52 mL / min, 54 mL / min, 56 mL / min, 58 mL / min, or 60 mL / min.
[0041] In some embodiments, the carrier gas includes at least one of nitrogen, argon, and helium.
[0042] In some embodiments, after condensing the gaseous piperidine in a condenser, the ruthenium-carbon catalyst is further cleaned using a solvent such as dichloromethane. Cleaning the catalyst with dichloromethane can restore the activity of a catalyst that has become deactivated after long-term use, enabling the catalyst to be reused and reducing costs.
[0043] In some embodiments, the flow rate of liquid pentanediamine is 0.1 mL / min to 1 mL / min. Within this flow rate range, the contact reaction between the vaporized pentanediamine and the catalyst is more complete. Optionally, the flow rate of liquid pentanediamine is 0.1 mL / min, 0.15 mL / min, 0.2 mL / min, 0.25 mL / min, 0.3 mL / min, 0.35 mL / min, 0.4 mL / min, 0.45 mL / min, 0.5 mL / min, 0.55 mL / min, 0.6 mL / min, 0.65 mL / min, 0.7 mL / min, 0.75 mL / min, 0.8 mL / min, 0.85 mL / min, 0.9 mL / min, 0.95 mL / min, or 1 mL / min.
[0044] In some embodiments, the mass ratio of the catalyst to the flow rate of liquid pentanediamine is 40 g:1 mL / min to 120 g:0.1 mL / min. Within this range of the catalyst-to-liquid pentanediamine flow rate ratio, the catalyst exhibits better catalytic effect on pentanediamine, resulting in a more complete reaction. Optionally, the mass ratio of the catalyst to the flow rate of liquid pentanediamine is 40 g:1 mL / min, 50 g:1 mL / min, 60 g:1 mL / min, 70 g:1 mL / min, 80 g:1 mL / min, 90 g:1 mL / min, 100 g:1 mL / min, 150 g:1 mL / min, 200 g:1 mL / min, 250 g:1 mL / min, 300 g:1 mL / min, 350 g:1 mL / min, 400 g:1 mL / min, 450 g:1 mL / min, 500 g:1 mL / min, 550 g:1 mL / min, 600 g:1 mL / min, etc. g:1mL / min, 650g:1mL / min, 700g:1mL / min, 750g:1mL / min, 800g:1mL / min, 850g:1mL / min, 900g:1mL / min, 950g:1mL / min, 1000g:1mL / min , 1050g:1mL / min, 1100g:1mL / min, 1120g:1mL / min, 1140g:1mL / min, 1150g:1mL / min, 1160g:1mL / min, 1180g:1mL / min, or 1200g:1mL / min.
[0045] In some embodiments, after condensing the gaseous piperidine by a condenser, the collected liquid piperidine is further purified by distillation.
[0046] In some embodiments, the method for preparing piperidine includes the following steps:
[0047] Liquid pentanediamine was pumped into the bottom of the reaction vessel through the feed pipe at a flow rate of 0.1 mL / min to 1 mL / min and vaporized to obtain gaseous pentanediamine.
[0048] Piperidine was prepared by contacting gaseous pentanediamine with a ruthenium-carbon catalyst and reacting at a temperature of 160℃~200℃.
[0049] Unreacted gaseous pentanediamine was condensed in a condenser at 120°C to 150°C and separated from gaseous piperidine, and the preparation process was repeated.
[0050] The prepared gaseous piperidine was blown into a condenser by a carrier gas, condensed and collected in the condenser, and the collected piperidine was purified by distillation.
[0051] After the catalyst is deactivated, the movable bottom valve of the reaction vessel is opened by the movable support rod, and the catalyst is washed with dichloromethane solvent.
[0052] In one embodiment, piperidine is prepared using a trickle reaction apparatus, and comprises the following steps:
[0053] Liquid pentanediamine was pumped into the bottom of the reaction vessel through the feed pipe at a flow rate of 0.1 mL / min to 1 mL / min and vaporized to obtain gaseous pentanediamine.
[0054] Pack 40g~120g of 2% ruthenium-carbon catalyst;
[0055] Piperidine was prepared by contacting gaseous pentanediamine with a ruthenium-carbon catalyst and reacting at a temperature of 160℃~200℃.
[0056] Unreacted gaseous pentanediamine was condensed in a condenser at 120°C to 150°C and separated from gaseous piperidine, and the preparation process was repeated.
[0057] The prepared gaseous piperidine was blown into a condenser by a carrier gas, condensed and collected in the condenser, and the collected piperidine was purified by distillation.
[0058] The catalyst was washed with dichloromethane solvent.
[0059] Reference Figure 1 Another embodiment of this application provides a trickle reaction device, including: a reaction container with an opening at the top, a feed pipe inserted into the reaction container, a top-closed collection container sleeved on the outside of the reactor, and a heating component for heating the reaction container. A ruthenium carbon catalyst is fixed inside the reaction container, and the catalyst is 1 cm to 2 cm away from the bottom surface of the reaction container. The outlet end of the feed pipe is lower than the fixed position of the catalyst.
[0060] In some embodiments, a condenser is provided on the side of the reaction vessel near the opening; the trickle reaction apparatus also includes a condenser, the feed end of which is connected to the collection container; the trickle reaction apparatus also includes an air inlet pipe inserted into the collection container, the air outlet end of which is close to the top of the collection container.
[0061] In some embodiments, the bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the reaction vessel, and the feed gasifies at the bottom. After the reaction is complete, the movable bottom valve is opened via the movable support rod, and the catalyst is washed with solvent to restore its activity.
[0062] In some embodiments, a trickle reaction apparatus is used to prepare piperidine using the above-described method for preparing piperidine.
[0063] The following are specific embodiments.
[0064] Example 1
[0065] In Example 1, the preparation method of piperidine is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.3 mL / min at room temperature. Nitrogen gas enters the reaction vessel from the feed pipe at a flow rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 180°C, the catalyst loading is 80 g, and the catalyst is ruthenium-carbon with a ruthenium content of 2%. In this example, the heating component is a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 10 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid, resulting in an overall reaction yield of 85% and a conversion rate of 90%. The crude product is purified by distillation, yielding 80% piperidine. The separated PDA can be recycled back into the fixed-bed reactor. The product's 1H NMR spectrum is as follows: 1 ¹H NMR (400MHz, CDCl₃): 2.78–2.81, m, 4H; 1.74, m, 1H; 1.50–1.55, m, 6H. The molecular weight determined by mass spectrometry was 85.09.
[0066] Example 2
[0067] In Example 2, the preparation method of piperidine is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.5 mL / min at room temperature. Nitrogen gas is introduced into the reaction vessel through the feed pipe at a flow rate of 40 mL / min, carrying gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 180°C, the catalyst loading is 80 g, and the catalyst is ruthenium-carbon with a ruthenium content of 2%. In this example, the heating component is a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 10 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid, resulting in an overall reaction yield of 70% and a conversion rate of 78%. The crude product is then distilled, and the separated PDA is recycled back into the fixed-bed reactor. The purified yield of piperidine is 65%.
[0068] Example 3
[0069] In Example 3, the preparation method of piperidine is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.2 mL / min at room temperature. Nitrogen gas enters the reaction vessel from the feed pipe at a flow rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 180°C, the catalyst loading is 80 g, and the catalyst is ruthenium-carbon with a ruthenium content of 2%. In this example, the heating component is a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 10 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid, resulting in an overall reaction yield of 80% and a conversion rate of 88%. The crude product is then distilled, and the separated PDA is recycled back into the fixed-bed reactor. The purified piperidine yield is 75%.
[0070] Example 4
[0071] In Example 4, the preparation method of piperidine is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.3 mL / min at room temperature. Nitrogen gas enters the reaction vessel from the feed pipe at a flow rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 180°C, the catalyst loading is 40 g, and the catalyst is ruthenium-carbon with a ruthenium content of 2%. In this example, the heating component is a furnace fitted outside the collection vessel, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 10 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid, resulting in an overall reaction yield of 60% and a conversion rate of 65%. The crude product is then distilled, and the separated PDA is recycled back into the fixed-bed reactor. The purified piperidine yield is 55%.
[0072] Example 5
[0073] In Example 5, the preparation method of piperidine is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.3 mL / min at room temperature. Nitrogen gas enters the reaction vessel from the feed pipe at a flow rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 180°C, the catalyst loading is 160 g, and the catalyst is ruthenium-carbon with a ruthenium content of 2%. In this example, the heating component is a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 10 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid. The overall reaction yield is calculated to be 74%, and the conversion rate to be 85%. The crude product is then distilled, and the separated PDA is recycled back into the fixed-bed reactor. The purified yield of piperidine is 65%.
[0074] Example 6
[0075] In Example 6, the preparation method of piperidine is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.3 mL / min at room temperature. Nitrogen gas enters the reaction vessel from the feed pipe at a flow rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 200°C, the catalyst loading is 80 g, and the catalyst is ruthenium-carbon with a ruthenium content of 2%. In this example, the heating component is a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 10 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid. The overall reaction yield is calculated to be 72%, and the conversion rate to be 78%. The crude product is then distilled, and the separated PDA is recycled back into the fixed-bed reactor. The purified yield of piperidine is 63%.
[0076] Example 7
[0077] In Example 7, the preparation method of piperidine is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.3 mL / min at room temperature. Nitrogen gas enters the reaction vessel from the feed pipe at a flow rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 160°C, the catalyst loading is 80 g, and the catalyst is ruthenium-carbon with a ruthenium content of 2%. In this example, the heating component is a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 10 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid. The overall reaction yield is calculated to be 63%, and the conversion rate to be 71%. The crude product is then distilled, and the separated PDA is recycled back into the fixed-bed reactor. The purified yield of piperidine is 59%.
[0078] Example 8
[0079] In Example 8, the preparation method of piperidine was as follows: Pentylene diamine (PDA) was pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.3 mL / min at room temperature. Nitrogen gas flowed into the reaction vessel from the feed pipe at a rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel was set to 180°C, the catalyst loading was 80 g, and the catalyst was ruthenium-carbon with a ruthenium content of 2%. In this example, the heating assembly was a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel was fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The top of the reaction vessel protruded 5 cm from the furnace and was fitted with a condensing jacket, serving as the condensation section. The condensation temperature was set to 130°C, which separated the gaseous pentylene diamine from the gaseous piperidine. After the reaction system reached equilibrium, the product was collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct was absorbed with water. Finally, quantitative analysis using standards was performed to calculate the piperidine content in the water and collected liquid. The overall reaction yield was calculated to be 77%, and the conversion rate to be 83%. The crude product was then distilled, and the separated PDA was reintroduced into the fixed-bed reactor for further reaction. The purified yield of piperidine was 73%.
[0080] Example 9
[0081] In Example 9, the preparation method of piperidine is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.3 mL / min at room temperature. Nitrogen gas enters the reaction vessel from the feed pipe at a flow rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 180°C, the catalyst loading is 80 g, and the catalyst is ruthenium-carbon with a ruthenium content of 2%. In this example, the heating component is a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 15 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after 8 hours of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid. The overall reaction yield is calculated to be 83%, and the conversion rate to be 92%. The crude product is then distilled, and the separated PDA is recycled back into the fixed-bed reactor. The purified yield of piperidine is 79%.
[0082] Example 10
[0083] The preparation method of piperidine in Example 10 is as follows: Pentylene diamine (PDA) is pumped into the reaction vessel of a trickle-flow reactor at a flow rate of 0.3 mL / min at room temperature. Nitrogen gas flows into the reaction vessel from the feed pipe at a flow rate of 40 mL / min, driving the gaseous piperidine to react with the catalyst. The reaction temperature of the reaction vessel is set to 180°C, the catalyst loading is 80 g, the catalyst is ruthenium-carbon, and the ruthenium content is 2%. In this example, the heating component is a furnace fitted outside the collection container, with a length of 90 cm. The catalyst in the reaction vessel is fixed in the middle of the furnace, i.e., between 40 cm and 60 cm from the bottom of the furnace. The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the vessel, and the PDA vaporizes at the bottom. After the reaction is complete and the catalyst needs to be cleaned for the next cycle, the support rod pushes the movable bottom valve to move, exposing the bottom pores. The cleaning solvent flows along the pores, along the support rod, into the quartz tube collector, and then out. The top reaction vessel protrudes 10 cm from the heating furnace and is surrounded by a condensing jacket, serving as the condensation section. The condensation temperature is set at 130℃ to separate gaseous pentanediamine from gaseous piperidine. After the reaction system reaches equilibrium, the product is collected after one month of continuous reaction. Simultaneously, the ammonia byproduct is absorbed with water. Finally, quantitative analysis using standards is performed to calculate the piperidine content in the water and collected liquid. The overall reaction yield is calculated to be 77%, and the conversion rate to be 82%. The crude product is then distilled, and the separated PDA is fed into a fixed-bed reactor. The purified piperidine yield is 73%. Partial catalyst deactivation was found. To address this, the catalyst was washed with dichloromethane (DCM) at a flow rate of 3 mL / min at 30°C for 3 hours. The washing solution was discharged from the reaction vessel through a movable bottom valve. The furnace temperature was raised to 100°C and dried with a nitrogen stream. The reaction was then continued in the original manner. After 8 hours of reaction, the product was collected, and the ammonia byproduct was absorbed with water. Finally, quantitative analysis using standards was performed to calculate the piperidine content in the water and collected solution. The overall reaction yield was calculated to be 90.2%, and the conversion rate was 85.3%. The crude product was purified by distillation, and the separated PDA was reintroduced into the fixed bed. The purified piperidine yield was 79.8%. This indicates that after solvent washing, the catalyst reaction yield and conversion rate can be restored to normal, and the reaction can be carried out continuously.
[0084] The catalysts and their mass used in the preparation of piperidine in Examples 1 to 10, the reaction temperature, the injection flow rate of pentanediamine, the distance of the catalyst from the bottom of the furnace, and the length of the top of the reaction vessel protruding from the furnace (i.e., the condenser section) are shown in Table 1 below:
[0085] Table 1
[0086]
[0087] The yields, conversions, and purification yields of the reactions for preparing piperidine in Examples 1 through 10 are shown in Table 2 below:
[0088] Table 2
[0089]
[0090] In Examples 1-10, the reaction temperature range for piperidine preparation was relatively low, resulting in a higher conversion rate. Comparing the results of Examples 1-10, it can be seen that, under constant conditions, the reaction yield was higher at a reaction temperature of 180°C. Under constant conditions, the reaction yield was higher when the flow rate of pentanediamine (PDA) was 0.3 mL / min. Under constant conditions, the reaction yield was higher when the ratio of catalyst mass to liquid pentanediamine flow rate was 80 g:0.3 mL / min. The distance of the reactor protruding from the top of the furnace served as a condenser section for separating gaseous pentanediamine and gaseous piperidine. Under constant conditions, a condenser section of 10 cm resulted in better separation of the product from gaseous PDA and a higher reaction yield. In Example 10, after one month of continuous reaction, the catalyst partially deactivated, leading to a decrease in reaction yield. After rinsing the catalyst with DCM, the catalyst activity was restored, and the reaction yield recovered.
[0091] 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.
[0092] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively 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 of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.
Claims
1. A process for the preparation of piperidine, characterized in that, Piperidine is prepared using a trickle-flow reaction apparatus, which includes a reaction vessel with an open top, a feed pipe inserted into the reaction vessel, a top-closed collection vessel fitted around the outside of the reaction vessel, and a heating assembly for heating the reaction vessel. The temperature of the reaction vessel is 160℃~200℃. A catalyst, which is a ruthenium-carbon catalyst, is fixed inside the reaction vessel. The catalyst is positioned 1cm~2cm below the bottom of the reaction vessel, and the outlet end of the feed pipe is lower than the fixed position of the catalyst. The preparation process includes: Liquid pentanediamine is added to the reaction vessel through the feed pipe; The liquid pentanediamine is vaporized using the heating assembly to obtain gaseous pentanediamine. The gaseous pentanediamine contacts and reacts with the catalyst; The reaction vessel is vertically positioned. A condenser section is provided on the side of the reaction vessel near the opening; After the gaseous pentanediamine contacts and reacts with the catalyst, the unreacted gaseous pentanediamine is condensed by the condensation section, thereby separating the unreacted gaseous pentanediamine from the gaseous piperidine obtained from the reaction.
2. The method for preparing piperidine according to claim 1, characterized in that, The condenser section is surrounded by a condenser jacket, and the condensation temperature is 120℃~150℃.
3. The method for preparing piperidine according to claim 1, characterized in that, The trickle-type reaction device also includes a condenser, the feed end of which is connected to the collection container; The process further includes condensing the unreacted gaseous pentanediamine through the condenser, and then condensing the gaseous piperidine through the condenser.
4. The process for the preparation of piperidine according to claim 3, characterized in that, The drip-type reaction device also includes an air inlet pipe inserted into the collection container, with the air outlet end of the air inlet pipe close to the top of the collection container; After the unreacted gaseous pentanediamine is condensed by the condenser and before the gaseous piperidine is condensed by the condenser, a carrier gas is introduced from the inlet pipe to blow the prepared gaseous piperidine from the collection container into the condenser.
5. The method for preparing piperidine according to claim 4, characterized in that, The flow rate of the carrier gas is 20 mL / min to 60 mL / min; And / or, the carrier gas includes at least one of nitrogen, argon and helium.
6. The method for preparing piperidine according to any one of claims 1 to 5, characterized in that, The flow rate of the liquid pentanediamine is 0.1 mL / min to 1 mL / min; And / or, the ruthenium content in the ruthenium-carbon catalyst is 2% by mass; And / or, the mass ratio of the ruthenium carbon catalyst to the flow rate of the liquid pentanediamine is 40 g: 1 mL / min to 120 g: 0.1 mL / min.
7. The method for preparing piperidine according to claim 6, characterized in that, The bottom of the reaction vessel includes a movable support rod with a movable bottom valve. During the reaction, the movable bottom valve closes the bottom of the reaction vessel, and the liquid pentanediamine is vaporized at the bottom of the reaction vessel. After the reaction is completed, the movable bottom valve is opened through the movable support rod, and the ruthenium-carbon catalyst is washed with dichloromethane solvent.