Method for producing methylpyrrolidone

Abstract

The present invention relates to the technical field of fine chemical product preparation, and is directed to a method for producing methylpyrrolidone. The method comprises the following steps: (1) subjecting butyrolactone to a ring-opening reaction with methylamine to obtain a stream 1; and (2) subjecting the stream 1, hydrogen, and optionally water to a ring-forming reaction in the presence of a catalyst; wherein, in the ring-opening reaction of step (1), the conversion rate of butyrolactone is not less than 80%. The method provided by the present invention has the advantages of short reaction time, low energy consumption, and high synthesis efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of fine chemical products, and in particular to a method for producing methylpyrrolidone. Background Art

[0002] N-Methylpyrrolidone (NMP) is a polar aprotic solvent with advantages such as a high boiling point, strong polarity, low viscosity, strong dissolving power, non-corrosiveness, low toxicity, and good chemical and thermal stability. It is primarily used for the extraction of aromatic hydrocarbons, the purification and separation of acetylene, olefins, and dienes, as a solvent for polymers and polymerization reactions, and as a solvent in semiconductor manufacturing. There are four main production technologies for N-methylpyrrolidone: the uncatalyzed synthesis of γ-butyrolactone and monomethylamine, the continuous uncatalyzed synthesis of γ-butyrolactone and mixed methylamines, the catalytic synthesis of γ-butyrolactone and monomethylamine, and the catalytic dehydrogenation-amination of 1,4-butanediol.

[0003] Patent application CN 1263523A discloses the uncatalyzed reaction of γ-butyrolactone with monomethylamine to synthesize N-methylpyrrolidone. However, the absence of a catalyst requires high temperatures and pressures, such as 250-310°C and 3-9 MPa. This also results in a long reaction time, with the total process taking 2-6 hours. Patent application CN 1384820A discloses a method for producing N-methylpyrrolidone by reacting γ-butyrolactone with mixed methylamines. BASF has improved this process, which includes three sequential reaction steps with gradually increasing temperatures. Step 3 has a reaction temperature of 280°C, a total reaction time of more than 4 hours, and a pressure of 4-10 MPa. South Korea's SK Corporation has explored a molecular sieve catalytic synthesis process using γ-butyrolactone with a purity of 99.0% or higher and a 40% monomethylamine solution as raw materials. The composite rare earth cerium / ZSM catalyst is added in an amount of 0.01%-0.5% of the monomethylamine solution, with a rare earth cerium content of 1%-10%. The reaction temperature is 180-250°C, the reaction pressure is 4.0-6.0 MPa, and the residence time is 0.5-2.5 hours (YS Yoon, HK Shin, BS Kwak. Ring conversion of γ-butyrolactone into N-methyl-2-pyrrolidone over modified zeolites. Catalysis Communications, 2002, 3:349-355.). Direct dehydrogenation of 1,4-butanediol followed by amination eliminates intermediate steps, reducing process operations and energy consumption, but it has numerous side reactions and is difficult to separate and purify, making it a currently unpopular method.

[0004] At present, the mainstream process for producing N-methylpyrrolidone on the market is to react valerolactone with methylamine as the raw material, but it has the problems of long process, high reaction pressure and high reaction temperature. Summary of the Invention

[0005] The present invention aims to overcome the problems of long process flow, high reaction pressure and high reaction temperature in the prior art production process of methyl pyrrolidone, and to provide a method for producing methyl pyrrolidone, which has the advantages of short reaction time, low energy consumption and high synthesis efficiency.

[0006] In order to achieve the above object, the present invention provides a method for producing methylpyrrolidone, which comprises the following steps:

[0007] (1) subjecting butyrolactone to a ring-opening reaction with methylamine to obtain logistics 1;

[0008] (2) in the presence of a catalyst, subjecting stream 1, hydrogen, and optionally water to a cyclization reaction;

[0009] Wherein, in the ring-opening reaction of step (1), the conversion rate of butyrolactone is not less than 80%.

[0010] Preferably, in the ring-opening reaction of step (1), the conversion rate of butyrolactone is 80-100%, more preferably 85-100%.

[0011] The present invention improves the efficiency of synthesizing methyl pyrrolidone by dividing the reaction into two stages and performing the reaction continuously, while the second step is under the action of a catalyst. The reaction process is divided into two synthesis stages, the first stage is a ring-opening amination stage, and the second stage is a dehydration cyclization stage. The reaction depth of the first stage is controlled, the reaction hot spots are eliminated, and the catalyst is fully utilized to achieve the purpose of reducing by-products and further improving the reaction efficiency. In the preferred embodiment, butyrolactone and methylamine are reacted in a microchannel reactor, which can achieve continuous operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a reaction flow chart of the present invention.

[0013] Description of Reference Numerals

[0014] 1- Buffer tank 2- Butyrolactone + methylamine raw material tank

[0015] 3-First microchannel reactor 4-Catalyst + lactone raw material tank

[0016] 5-Hydrogen 6-Second microchannel reactor

[0017] 7-Flash tank 8-Distillation tower DETAILED DESCRIPTION

[0018] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0019] The present invention provides a method for producing methylpyrrolidone, which comprises the following steps:

[0020] (1) subjecting butyrolactone to a ring-opening reaction with methylamine to obtain logistics 1;

[0021] (2) in the presence of a catalyst, subjecting stream 1, hydrogen, and optionally water to a cyclization reaction;

[0022] Wherein, in the ring-opening reaction of step (1), the conversion rate of butyrolactone is not less than 80%.

[0023] According to the method of the present invention, preferably, in the ring-opening reaction in step (1), the conversion rate of butyrolactone is 80-100%, preferably 85-100%.

[0024] By adopting the above technical scheme, the reaction process is divided into two synthesis stages: the first stage is the ring-opening amination stage, and the second stage is the dehydration cyclization stage. The first stage controls the reaction depth. Because the dehydration cyclization stage in the second stage is a reversible reaction, if the ring-opening reaction in the first stage is insufficient, more stringent reaction conditions must be adopted in the second stage to promote the ring-opening of butyrolactone. This process not only produces complex side reactions, making subsequent separation more difficult, but also increases energy consumption. The present invention controls the reaction depth in the first reaction stage so that the conversion rate of butyrolactone is greater than 80%, and the ring-opening reaction produces an amide intermediate. In the second stage, by adding a catalyst and optionally water, and passing hydrogen, the dehydration cyclization is accelerated to form N-methylpyrrolidone. Water is preferably added in this stage, and adding water will further promote the occurrence of the cyclization reaction. The two stages are completed independently and continuously, improving the reaction efficiency and enabling the entire reaction to be completed under relatively mild conditions.

[0025] In the present invention, the amount of butyrolactone and methylamine used in step (1) is not particularly limited, as long as the ring-opening reaction can be successfully completed. Preferably, the mass ratio of butyrolactone to methylamine is 1:0.9-4, more preferably 1:1-1.5.

[0026] According to the method of the present invention, the conditions for the ring-opening reaction only need to satisfy the above-mentioned conversion rate of butyrolactone. Preferably, the conditions for the ring-opening reaction in step (1) include: a reaction temperature of 180-260°C, a pressure of 0.2-1.5 MPa, and a reaction residence time of 5-30 min; further preferably, the conditions for the ring-opening reaction in step (1) include: a reaction temperature of 185-240°C, a pressure of 0.2-1.0 MPa, and a reaction residence time of 5-20 min. The purpose of adopting this preferred embodiment is to allow the ring-opening reaction to react independently, minimize the impact of the second step reaction, and improve the efficiency of subsequent reactions.

[0027] According to the method of the present invention, the logistics 1 obtained by the ring-opening reaction in step (1) contains butanamide and unreacted butyrolactone and methylamine.

[0028] According to the method of the present invention, preferably, the conditions for the cyclization reaction in step (2) include: a reaction temperature of 120-180°C, a pressure of 0.2-1.5 MPa, and a reaction residence time of 10-60 minutes; further preferably, the reaction temperature is 130-160°C, the pressure is 0.2-1.0 MPa, and the reaction residence time is 15-45 minutes. The advantage of adopting this preferred embodiment is that the efficiency of the second step is improved, interference between the first and second steps is avoided, and the catalyst is more effective.

[0029] In the present invention, there is no specific limitation on the amount of the catalyst used in step (2), as long as the cyclization reaction can proceed smoothly. Preferably, the amount of the catalyst added is 0.1-10% of the total mass of butyrolactone and methylamine, more preferably 0.1-5%.

[0030] In a preferred embodiment, the amount of water added is 1-30% of the total mass of butyrolactone and methylamine. Adding a specific amount of water during the cyclization reaction can further promote the cyclization reaction and accelerate the dehydration to form methylpyrrolidone. To further promote the cyclization reaction and improve the reaction efficiency, the amount of water added is more preferably 3-20%.

[0031] In a preferred embodiment, hydrogen is introduced during the cyclization reaction to promote the cyclization reaction and improve the reaction efficiency. The amount of hydrogen used in the present invention can be selected from a wide range. Preferably, the amount of hydrogen used is 0.1-10 ml / min.

[0032] In the present invention, there is no specific limitation on the order of mixing the stream 1, water, catalyst, and hydrogen in step (2). Preferably, the ring-opening reaction in step (2) comprises: first mixing the water with the catalyst, then mixing with hydrogen, and finally contacting the resulting stream with the stream 1 for reaction.

[0033] In the present invention, the logistics obtained from the cyclization reaction in step (2) includes N-methylpyrrolidone and unreacted material components.

[0034] According to the method of the present invention, under the action of a catalyst, the synthesis efficiency of methyl pyrrolidone can be improved. There is no specific limitation on the type of catalyst in the present invention, and those skilled in the art can make a conventional selection according to specific needs. Preferably, the catalyst includes a carrier and a metal active component.

[0035] According to the method of the present invention, there is no specific limitation on the type of carrier. Preferably, the carrier is selected from at least one of ZSM-5, β molecular sieve, Y molecular sieve, TiO2 and ZrO2, more preferably ZSM-5, TiO2 and ZrO2.

[0036] According to the method of the present invention, there is no specific limitation on the type of metal active component, and those skilled in the art can select it according to specific needs. Preferably, the metal active component is selected from at least one of noble metals.

[0037] In a preferred embodiment, the noble metal is selected from at least one of Pt, Ru, Pd, and Ir, more preferably Pt and Ir. The advantage of adopting this preferred embodiment is that the use of a catalyst can improve the reaction efficiency, achieve equilibrium more quickly within the same reaction time, and increase the reaction completion.

[0038] In the present invention, there is no particular limitation on the amount of the metal active component. Preferably, the content of the metal active component is 0.1-5%, more preferably 0.1-1%, based on the total weight of the catalyst.

[0039] In the present invention, there are no particular limitations on the preparation method of the catalyst, as long as the catalyst can be prepared. In a preferred embodiment, for example, an impregnation method can be used to introduce the precious metal precursor onto the support, followed by reduction with a reducing agent (preferably an aqueous NBH4 solution), and finally drying. The present invention does not particularly limit the specific operation of the impregnation method, and conventional methods in the art can be used, and the present invention will not be further described here.

[0040] According to the present invention, the type of the noble metal precursor solution is not particularly limited, and can be selected from water-soluble compounds of noble metal active components, such as chloroplatinic acid.

[0041] According to the present invention, a metal active component precursor is dissolved in a solvent (such as water) to prepare a solution containing the metal active component precursor.

[0042] According to the present invention, the specific conditions for reduction can be selected in a wide range. Preferably, the reduction temperature is -10-10°C and the time is 1-4 hours.

[0043] According to the present invention, the specific conditions for drying can be selected in a wide range. Preferably, the drying temperature is 60-90°C and the drying time is 1-4 hours.

[0044] The present invention does not particularly limit the preparation method of the carrier. Any preparation method known in the art can be used in the present invention. Preferably, the catalyst with TiO2 as the carrier can be prepared by the following method: S1. Using a molten salt method, a titanium precursor (preferably tetrabutyl titanate) and a molten salt additive (preferably sodium nitrate) are mixed and ball-milled, dried, and then calcined to obtain a calcined product. S2. The calcined product is stirred in deionized water and then filtered and dried to obtain a TiO2 solid.

[0045] According to the present invention, there is no specific limitation on the ball milling method in S1, and conventional ball milling methods in the art are applicable to the present invention, such as dry ball milling.

[0046] According to the present invention, the drying and calcining conditions in S1 and S2 can be selected over a wide range. Preferably, the drying temperature is 80-200°C for 1-10 hours, and the calcining temperature is 300-400°C for 1-4 hours.

[0047] According to the present invention, the specific conditions for stirring in S2 can be selected in a wide range. Preferably, the temperature is 60-100° C. and the time is 1-12 hours.

[0048] According to the present invention, preferably, solid-liquid separation is performed after stirring in S2. There is no specific limitation on the method of solid-liquid separation in the present invention, as long as the purpose of solid-liquid separation is achieved, such as filtration.

[0049] According to the method of the present invention, preferably, the ring-opening reaction in step (1) and the ring-forming reaction in step (2) are both carried out in a microchannel reactor. The advantage of adopting this preferred embodiment is that the lactone and methylamine are reacted in a microreactor, the reaction temperature can be precisely controlled, the reaction hot spots are eliminated, the catalyst is fully utilized, and the purpose of reducing by-products and improving reaction efficiency is achieved.

[0050] In a preferred embodiment, the inner diameter of the pipe of the microchannel reactor is 0.1-2 mm.

[0051] In a preferred embodiment, the microchannel reactor is made of quartz glass, borosilicate glass, silicon carbide, polyetheretherketone tube or Hastelloy.

[0052] The method of the present invention preferably further comprises step (3): separating methylamine from the stream obtained in step (2). This preferred embodiment is intended to remove methylamine from the target product, thereby reducing its adverse effects on subsequent target product purification processes and improving the yield of the target product.

[0053] In a preferred embodiment, the separation in step (3) is performed in a flash tank 7. The reaction conditions in the flash tank 7 can be selected in a wide range as long as methylamine can be separated. In a preferred embodiment, the temperature in the flash tank is 10-50° C. and the pressure is 0.02-0.08 MPa.

[0054] The method according to the present invention further includes a buffering stage. Preferably, the method further includes recycling the methylamine separated in step (3) back to the buffer tank 1, so that the methylamine is temporarily stored in the buffer tank 1 and then recycled into the butyrolactone + methylamine raw material tank 2, thereby improving the utilization rate of the methylamine.

[0055] According to the method of the present invention, preferably, the method comprises subjecting the material obtained in step (3) (the material obtained after separating methylamine) to reduced pressure distillation.

[0056] In a preferred embodiment, the reduced pressure distillation conditions include: a bottom temperature of 10-60° C. and a pressure of 0.01-0.05 MPa. The advantage of adopting this preferred embodiment is that the target product methyl pyrrolidone can be purified to obtain methyl pyrrolidone of higher purity.

[0057] According to the method of the present invention, preferably, the method is continuous production. In the case of this preferred embodiment, the ring-opening reaction stage and the ring-forming reaction stage are independently and continuously carried out, so that the entire reaction process occurs continuously, greatly shortening the reaction time, reducing energy consumption, and improving the yield of methyl pyrrolidone.

[0058] The present invention will be described in detail below through examples. In the following examples, all raw materials used are commercially available unless otherwise specified.

[0059] The conversion of butyrolactone and the yield of methyl pyrrolidone in the present invention are calculated by the following formula:

[0060]

[0061]

[0062] Example 1

[0063] Preparation of Pt / TiO2 catalyst:

[0064] S1. Weigh 2.04 g (6 mol) of tetrabutyl titanate and 15 g of sodium nitrate, mix and ball-mill, and dry the obtained solid product at 80° C. for 12 hours.

[0065] S2. The dried product was taken out and calcined in a muffle furnace at 350° C. for 2 hours. The calcined product was stirred in deionized water at 80° C. for 12 hours and then filtered and dried to obtain a TiO2 solid product.

[0066] S3. Weigh 2 g of the TiO2 solid product and disperse it in 15 mL of a 0.1 wt% aqueous solution of chloroplatinic acid, stirring for 12 h. The product was then reduced with a 1 M aqueous solution of NBH4 in a 0°C ice-water bath for 2 h. The catalyst was filtered and washed, and vacuum-dried at 80°C for 8 h. ICP analysis revealed a Pt content of 0.2 wt% in the catalyst.

[0067] The production steps of methyl pyrrolidone are as follows: Figure 1 As shown:

[0068] (1) 40 g of butyrolactone and 50 g of methylamine were placed in a butyrolactone + methylamine raw material tank 2 and mixed thoroughly. The mixture was pumped into the first microchannel reactor 3 using a metering pump at an input rate of 4 g / min.

[0069] (2) The reaction was carried out in the first microchannel reactor 3 at a temperature of 160° C., a pressure of 0.5 MPa, a residence time of 20 min, and a detected butyrolactone conversion rate of 91%;

[0070] (3) 15 g of water and 1 g of 0.2% Pt / TiO2 catalyst were placed in the catalyst + lactone raw material tank 4 and mixed at a flow rate of 0.8 g / min. The material was pumped in with a metering pump, and the inflow of hydrogen 5 was controlled at 0.5 ml / min. The stream and the stream obtained in step (2) were pumped into the second microchannel reactor 6 with a pump. The reaction temperature was 160°C, the pressure was 1.0 MPa, and the reaction residence time was 30 min.

[0071] (4) After the reaction, the material was transferred to a flash tank 7 for flash evaporation (temperature 40°C, pressure 0.05 MPa). After separating the methylamine, the resulting material was transferred to a vacuum distillation apparatus (rectifier 8) for purification (bottom temperature 60°C, pressure 0.05 MPa) to obtain methylpyrrolidone. The material was sampled and analyzed at the outlet of the second microchannel reactor 6. Chromatographic analysis showed a methylpyrrolidone yield of 98.9%.

[0072] Example 2

[0073] Preparation of Pt / ZrO2 catalyst:

[0074] S1. Weigh 2.30 g (6 mol) of tetrabutyl zirconate and 15 g of sodium nitrate, mix and ball-mill, and dry the obtained solid product at 80° C. for 12 hours.

[0075] S2. The dried product was taken out and calcined in a muffle furnace at 330° C. for 2 hours. The calcined product was stirred in deionized water at 70° C. for 12 hours and then filtered and dried to obtain a ZrO 2 solid product.

[0076] S3. Weigh 2 g of the ZrO2 solid product and disperse it in 10 mL of a 0.5 wt% aqueous solution of chloroplatinic acid, stirring for 8 h. The product was then reduced with a 1 M aqueous solution of NBH4 in a 5°C ice-water bath for 2 h. The catalyst was filtered and washed, and then vacuum-dried at 80°C for 8 h. ICP analysis of the catalyst revealed a Pt content of 0.9 wt%.

[0077] The production steps of methyl pyrrolidone are as follows: Figure 1 As shown:

[0078] (1) 50 g of butyrolactone and 56 g of methylamine were placed in a butyrolactone + methylamine raw material tank 2 and mixed thoroughly. The mixture was pumped into the first microchannel reactor 3 using a metering pump at an input rate of 5 g / min.

[0079] (2) The reaction was carried out in the first microchannel reactor 3 at a temperature of 240° C., a pressure of 0.4 MPa, a residence time of 10 min, and a detected butyrolactone conversion rate of 95%;

[0080] (3) 20 g of water and 1 g of 0.9% Pt / ZrO2 catalyst were placed in the catalyst + lactone raw material tank 4 and mixed at a flow rate of 0.8 g / min. The material was pumped in with a metering pump, and the flow rate of hydrogen 5 was controlled to be 2 ml / min. The stream and the stream obtained in step (2) were pumped into the second microchannel reactor 6 with a pump. The reaction temperature was 150°C, the pressure was 0.8 MPa, and the reaction residence time was 30 min.

[0081] (4) After the reaction, the material was transferred to a flash tank 7 for flash evaporation (temperature 40°C, pressure 0.05 MPa). After separating the methylamine, the resulting material was transferred to a vacuum distillation apparatus (rectifier 8) for purification (bottom temperature 40°C, pressure 0.03 MPa) to obtain methylpyrrolidone. The material was sampled and analyzed at the outlet of the second microchannel reactor 6. Chromatographic analysis showed a methylpyrrolidone yield of 98.8%.

[0082] Example 3

[0083] Preparation of Ir / ZrO2 catalyst:

[0084] S1. Weigh 2.30 g (6 mol) of tetrabutyl zirconate and 15 g of sodium nitrate, mix and ball-mill, and dry the obtained solid product at 80° C. for 12 hours.

[0085] S2. The dried product was taken out and calcined in a muffle furnace at 330° C. for 2 hours. The calcined product was stirred in deionized water at 70° C. for 12 hours and then filtered and dried to obtain a ZrO 2 solid product.

[0086] S3. Weigh 2 g of the ZrO2 solid product and disperse it in 15 mL of a 0.1 wt% aqueous solution of chloroiridic acid, stirring for 8 h. The solution was then reduced with a 1 M aqueous solution of NBH4 in a 5°C ice-water bath for 2 h. The resulting catalyst was filtered and washed, and vacuum-dried at 80°C for 8 h. ICP analysis of the catalyst revealed an Ir content of 0.2 wt%.

[0087] The production steps of methyl pyrrolidone are as follows: Figure 1 As shown:

[0088] (1) 40 g of butyrolactone and 45 g of methylamine were placed in a butyrolactone + methylamine raw material tank 2 and mixed thoroughly. The mixture was pumped into the first microchannel reactor 3 using a metering pump at an input rate of 4 g / min.

[0089] (2) The reaction was carried out in the first microchannel reactor 3 at a temperature of 220° C., a pressure of 0.4 MPa, a residence time of 10 min, and a detected butyrolactone conversion rate of 90%;

[0090] (3) 10 g of water and 3 g of 0.2% Pt / ZrO2 catalyst were placed in the catalyst + lactone raw material tank 4 and mixed at a flow rate of 0.8 g / min. The material was pumped in with a metering pump, and the inflow of hydrogen 5 was controlled at 4 ml / min. The stream and the stream obtained in step (2) were pumped into the second microchannel reactor 6 with a pump. The reaction temperature was 120°C, the pressure was 0.5 MPa, and the reaction residence time was 40 min.

[0091] (4) After the reaction, the material was transferred to a flash tank 7 for flash evaporation (temperature 40°C, pressure 0.05 MPa). After separating the methylamine, the resulting material was transferred to a vacuum distillation apparatus (rectifier 8) for purification (bottom temperature 40°C, pressure 0.03 MPa) to obtain methylpyrrolidone. The material was sampled and analyzed at the outlet of the second microchannel reactor 6. Chromatographic analysis showed a methylpyrrolidone yield of 99.1%.

[0092] Example 4

[0093] Preparation of Pt / ZSM-5 catalyst:

[0094] S1. Weigh 10 g of ZSM-5 powder (purchased from Nankai Catalyst Factory, with a silicon-aluminum ratio of 25) and ball-mill it. Dry the resulting solid product at 80° C. for 12 hours.

[0095] S2. The dried product was taken out and calcined in a muffle furnace at 330° C. for 2 hours. The calcined product was stirred in deionized water at 70° C. for 12 hours and then filtered and dried to obtain a ZSM-5 precursor solid product.

[0096] S3. Weigh 2 g of the ZSM-5 solid product and disperse it in 15 mL of a 0.1 wt % aqueous solution of chloroplatinic acid, stirring for 8 h. The mixture is then reduced with a 1 M aqueous solution of NBH4 in a 5° C. ice-water bath for 2 h. The catalyst is filtered and washed, and vacuum-dried at 80° C. for 8 h. ICP analysis of the catalyst reveals a Pt content of 0.2 wt %.

[0097] The production steps of methyl pyrrolidone are as follows: Figure 1 As shown:

[0098] (1) 40 g of butyrolactone and 50 g of methylamine were placed in a butyrolactone + methylamine raw material tank 2 and mixed thoroughly. The mixture was pumped into the first microchannel reactor 3 using a metering pump at an input rate of 4 g / min.

[0099] (2) The reaction was carried out in the first microchannel reactor 3 at a temperature of 200° C., a pressure of 1.0 MPa, a residence time of 20 min, and a detected butyrolactone conversion rate of 81%;

[0100] (3) 15 g of water and 1 g of 0.2% Pt / ZSM-5 catalyst were placed in a catalyst + lactone raw material tank 4 and mixed at a flow rate of 0.8 g / min. The material was pumped into the tank using a metering pump, while the flow rate of hydrogen 5 was controlled to be 0.5 ml / min. The material and the material obtained in step (2) were pumped into a second microchannel reactor 6 using a pump. The reaction temperature was 160° C., the pressure was 1.0 MPa, and the reaction residence time was 30 min. (4) After the reaction, the material was transferred to a flash tank 7 for flash evaporation (temperature of 40° C., pressure of 0.05 MPa). The material obtained after separating methylamine was entered into a vacuum distillation apparatus (rectifying tower 8) for purification (tower bottom temperature of 60° C., pressure of 0.05 MPa) to obtain methyl pyrrolidone. The material was sampled and analyzed at the outlet of the second microchannel reactor 6. According to chromatographic analysis, the yield of methyl pyrrolidone was 92.3%.

[0101] Example 5

[0102] Preparation of Pd / TiO2 catalyst:

[0103] S1. Weigh 2.04 g (6 mol) of tetrabutyl titanate and 15 g of sodium nitrate, mix and ball-mill, and dry the obtained solid product at 80° C. for 12 hours.

[0104] S2. The dried product was taken out and calcined in a muffle furnace at 350° C. for 2 hours. The calcined product was stirred in deionized water at 80° C. for 12 hours and then filtered and dried to obtain a TiO2 solid product.

[0105] S3. Weigh 2 g of the TiO2 solid product and disperse it in 15 mL of a 0.1 wt% aqueous solution of chloropalladic acid, stirring for 12 h. The product was then reduced with a 1 M aqueous solution of NBH4 in a 0°C ice-water bath for 2 h. The catalyst was filtered and washed, and vacuum-dried at 80°C for 8 h. ICP analysis of the catalyst revealed a Pd content of 0.2 wt%.

[0106] The production steps of methyl pyrrolidone are as follows: Figure 1 As shown:

[0107] (1) 40 g of butyrolactone and 60 g of methylamine were placed in a butyrolactone + methylamine raw material tank 2 and mixed thoroughly. The mixture was pumped into the first microchannel reactor 3 using a metering pump at an input rate of 3 g / min.

[0108] (2) The reaction was carried out in the first microchannel reactor 3 at a temperature of 220° C., a pressure of 0.4 MPa, a residence time of 10 min, and a detected butyrolactone conversion rate of 83%;

[0109] (3) 15 g of water and 1 g of 0.2% Pd / TiO2 catalyst were placed in the catalyst + lactone raw material tank 4 and mixed at a flow rate of 0.8 g / min. The material was pumped in with a metering pump, and the inflow of hydrogen 5 was controlled at 3 ml / min. The stream and the stream obtained in step (2) were pumped into the second microchannel reactor 6 with a pump. The reaction temperature was 160°C, the pressure was 0.8 MPa, and the reaction residence time was 20 min.

[0110] (4) After the reaction, the material was transferred to a flash tank 7 for flash evaporation (temperature 30°C, pressure 0.05 MPa). After separating the methylamine, the resulting material was transferred to a vacuum distillation apparatus (rectifier 8) for purification (bottom temperature 40°C, pressure 0.01 MPa) to obtain methylpyrrolidone. The material was sampled and analyzed at the outlet of the second microchannel reactor 6. Chromatographic analysis showed that the yield of methylpyrrolidone was 89.6%.

[0111] Example 6

[0112] Preparation of Ru / ZrO2 catalyst:

[0113] S1. Weigh 2.30 g (6 mol) of tetrabutyl zirconate and 15 g of sodium nitrate, mix and ball-mill, and dry the obtained solid product at 80° C. for 12 hours.

[0114] S2. The dried product was taken out and calcined in a muffle furnace at 330° C. for 2 hours. The calcined product was stirred in deionized water at 70° C. for 12 hours and then filtered and dried to obtain a ZrO 2 solid product.

[0115] S3. Weigh 2 g of the ZrO2 solid product and disperse it in 10 mL of a 0.1 wt% aqueous solution of ruthenium trichloride, stirring for 8 h. The mixture is then reduced with a 1 M aqueous solution of NBH4 in a 5°C ice-water bath for 2 h. The catalyst is filtered and washed, and then vacuum-dried at 80°C for 8 h. ICP analysis of the catalyst reveals a Ru content of 0.2 wt%.

[0116] The production steps of methyl pyrrolidone are as follows: Figure 1 As shown:

[0117] (1) 40 g of butyrolactone and 50 g of methylamine were placed in a butyrolactone + methylamine raw material tank 2 and mixed thoroughly. The mixture was pumped into the first microchannel reactor 3 using a metering pump at an input rate of 4 g / min.

[0118] (2) reacting in the first microchannel reactor 3 at a reaction temperature of 200° C., a pressure of 1.0 MPa, a reaction residence time of 3 min, and a detected butyrolactone conversion rate of 75%;

[0119] (3) 17 g of water and 3.5 g of 0.2% Ru / ZrO2 catalyst were placed in the catalyst + lactone raw material tank 4 and mixed at a flow rate of 0.8 g / min. The material was pumped in with a metering pump, and the inflow of hydrogen 5 was controlled at 0.5 ml / min. The stream and the stream obtained in step (2) were pumped into the second microchannel reactor 6 with a pump. The reaction temperature was 160°C, the pressure was 1.0 MPa, and the reaction residence time was 30 min.

[0120] (4) After the reaction, the material was transferred to a flash tank 7 for flash evaporation (temperature 40°C, pressure 0.05 MPa). After separating the methylamine, the resulting material was transferred to a vacuum distillation apparatus (rectifier 8) for purification (bottom temperature 60°C, pressure 0.05 MPa) to obtain methylpyrrolidone. The material was sampled and analyzed at the outlet of the second microchannel reactor 6. Chromatographic analysis showed that the yield of methylpyrrolidone was 86.6%.

[0121] Comparative Example 1

[0122] The method of Example 1 was followed, except that no catalyst was added in step (3). Chromatographic analysis showed that the yield of methyl pyrrolidone was 55.9%.

[0123] Comparative Example 2

[0124] Comparative Example 2 is to control the conversion rate of butyrolactone in the first stage to 50.8%. Other reaction conditions are the same as those in Example 1.

[0125] (1) 40 g of butyrolactone and 50 g of methylamine were placed in a butyrolactone + methylamine raw material tank 2 and mixed thoroughly. The mixture was pumped into the first microchannel reactor 3 using a metering pump at a rate of 4 ml / min.

[0126] (2) The reaction was carried out in the first microchannel reactor 3 at a temperature of 160° C., a pressure of 0.5 MPa, and a residence time of 4 min. The conversion rate of butyrolactone was detected to be 50.8%.

[0127] (3) 20 g of water and 1 g of 0.2% Pt / TiO2 catalyst were mixed in the catalyst + lactone raw material tank 4 at a flow rate of 0.8 g / min. The raw materials were pumped in with a metering pump while controlling the inflow of hydrogen 5 to 0.5 ml / min. The stream and the stream obtained in step (2) (at a flow rate of 4 g / min) were pumped into the second microchannel reactor 6 with a pump. The reaction temperature was 160°C, the pressure was 1.0 MPa, and the reaction residence time was 30 min.

[0128] (4) After the reaction, the material was transferred to a flash tank 7 for flash evaporation (temperature 40°C, pressure 0.05 MPa). After separating the methylamine, the resulting material was transferred to a vacuum distillation apparatus (rectifier 8) for purification (bottom temperature 60°C, pressure 0.05 MPa) to obtain methylpyrrolidone. The material was sampled and analyzed at the outlet of the second microchannel reactor 6. Chromatographic analysis showed a methylpyrrolidone yield of 76.8%.

[0129] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for producing methylpyrrolidone, the method comprising the steps of: (1) subjecting butyrolactone to a ring-opening reaction with methylamine to obtain stream 1; (2) In the presence of a catalyst, stream 1, hydrogen, and water undergo a cyclization reaction; in, In the ring-opening reaction of step (1), the conversion rate of butyrolactone is not less than 80%; The catalyst comprises a carrier and a metal active component; the carrier is selected from at least one of ZSM-5, β molecular sieve, Y-type molecular sieve, TiO2 and ZrO2; the metal active component is selected from at least one of Pt, Ru, Pd and Ir; The conditions of the ring-opening reaction in step (1) include: reaction temperature of 185-240°C, pressure of 0.2-1.0 MPa, and reaction residence time of 10-20 min; The conditions of the cyclization reaction in step (2) include: reaction temperature of 120-180°C, pressure of 0.2-1.5 MPa, and reaction residence time of 10-40 min; The ring-opening reaction in step (1) and the ring-forming reaction in step (2) are both carried out in a microchannel reactor.

2. The method according to claim 1, wherein In the ring-opening reaction of step (1), the conversion rate of butyrolactone is 80-100%.

3. The method according to claim 2, wherein: In the ring-opening reaction of step (1), the conversion rate of butyrolactone is 85-100%.

4. The method according to claim 1, wherein The mass ratio of butyrolactone to methylamine is 1:0.9-4.

5. The method according to claim 4, wherein The mass ratio of butyrolactone to methylamine is 1:1-1.

5.

6. The method according to claim 1, wherein The conditions for the cyclization reaction in step (2) include: a reaction temperature of 130-160° C., a pressure of 0.2-1.0 MPa, and a reaction residence time of 15-40 min.

7. The method according to any one of claims 1 to 6, wherein: The added amount of the catalyst is 0.1-10% of the total mass of butyrolactone and methylamine.

8. The method according to claim 7, wherein: The added amount of the catalyst is 0.1-5% of the total mass of butyrolactone and methylamine.

9. The method according to any one of claims 1 to 6, wherein: The amount of water added is 1-30% of the total mass of butyrolactone and methylamine.

10. The method according to claim 9, wherein: The amount of water added is 3-25% of the total mass of butyrolactone and methylamine.

11. The method according to any one of claims 1 to 6, wherein: The amount of hydrogen used is 0.1-5 ml / min.

12. The method according to any one of claims 1 to 6, wherein: The cyclization reaction in step (2) comprises: first mixing water with the catalyst, then mixing with hydrogen, and finally contacting the obtained stream with the stream 1 for reaction.

13. The method according to any one of claims 1 to 6, wherein: Based on the total weight of the catalyst, the content of the metal active component is 0.1-5%.

14. The method according to claim 13, wherein Based on the total weight of the catalyst, the content of the metal active component is 0.1-1%.

15. The method according to claim 1, wherein The inner diameter of the pipeline of the microchannel reactor is 0.1-2 mm.

16. The method according to claim 15, wherein The microchannel reactor is made of quartz glass, borosilicate glass, silicon carbide, polyetheretherketone tube or Hastelloy.

17. The method according to any one of claims 1 to 6, wherein: The method further comprises step (3): separating methylamine from the stream obtained in step (2).

18. The method according to claim 17, wherein: The separation in step (3) is carried out in a flash tank.

19. The method according to claim 18, wherein The temperature in the flash tank is 10-50° C., and the pressure is 0.02-0.08 MPa.

20. The method according to claim 19, wherein The method comprises subjecting the stream obtained in step (3) to vacuum distillation.

21. The method according to claim 20, wherein The conditions for the reduced pressure distillation include: a bottom temperature of 10-60° C. and a pressure of 0.01-0.05 MPa.

22. The method according to any one of claims 1 to 6, wherein: This method is a continuous production method.

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