Microchannel reactor and process for the preparation of n-methylpyrrolidone

Abstract

The present application relates to the field of microchannel device, disclose a kind of microchannel reaction device and the preparation method of N-methylpyrrolidone, including the mixer with liquid phase feed port and gas phase feed port and the reactor that is sealingly communicated mixer and is provided product outlet;Multiple nested microscale sleeve are built-in in the mixer, and liquid phase raw material and gas phase raw material are entered into reactor after being mixed efficiently in the liquid phase fluid passage of mixer;Multiple groups of interleaved grid plate mixing inserts are built-in in the reactor, and after being mutually staggered and superimposed, form tortuous microscale reaction channel, and reaction raw material is reacted efficiently in reactor and ensure that gas phase raw material has higher utilization rate.The microchannel reaction device provided by the present application utilizes microscale effect to effectively process intensify for multiphase reaction system, while providing a solution without additional introduction of solvent and lower reaction pressure for N-methylpyrrolidone synthesis process, which can ensure efficient mixing reaction efficiency and good safety in the whole process.

Description

Technical Field

[0001] This invention relates to the field of microchannel devices, and more specifically to a microchannel reaction apparatus and a method for preparing N-methylpyrrolidone. Background Technology

[0002] Since its formal introduction in Europe and the United States in the 1990s, microchannel technology has received increasing attention and become a cutting-edge and hot topic in chemical engineering. In industrial applications, microreactor technology has been highly valued by governments and enterprises. The core objective is to develop new process intensification equipment, establish miniaturized, modular, continuous, and intelligent new chemical plants, and achieve safer, more environmentally friendly, more efficient, and more economical production methods. Research on multiple industrial projects covering pharmaceuticals, chemical intermediates, and polymers has shown that microreactor technology can not only be successfully applied in actual industrial production, but also has significant advantages over traditional reaction equipment in terms of yield, production capacity, space-time yield, equipment investment, operating costs, and environmental impact.

[0003] In recent years, with the requirements of safety, environmental protection and cost reduction, microchemical technology has been increasingly used in pharmaceuticals, dyes and some bulk chemicals. However, because the flow patterns and mass transfer behaviors in microreactors are completely different from those in traditional reactors, there are many complex heterogeneous reaction processes in fine chemicals. The production processes of many high-value-added fine chemical products include multiple processes such as heat transfer, mixing, reaction, separation and even external field enhancement. Although precise control of the product production process can be achieved in microchannel reactors, existing continuous flow synthesis technology does not have very mature commercial products and process routes for multi-process coupling in heterogeneous systems.

[0004] US6248902 describes a continuous, non-catalytic synthesis of N-methylpyrrolidone from γ-butyrolactone and methylamine in a three-stage reaction section under pressures of 3.0–9.0 MPa: a) First-stage reaction section operating temperature 150–220 °C, residence time 5–30 min; b) Second-stage reaction section operating temperature 220–270 °C, residence time 1–3 h; c) Third-stage reaction section operating temperature 250–310 °C, residence time 0.5–2 h. This synthesis technique suffers from problems such as high reaction temperature, high reaction pressure, long reaction cycle, and high safety risks.

[0005] CN107474003 discloses a method for the continuous flow synthesis of N-methylpyrrolidone, which utilizes a capillary microreactor to enhance the mixed reaction process of γ-butyrolactone and methylamine, achieving efficient continuous synthesis of N-methylpyrrolidone under low pressure conditions. However, this process uses a large amount of ethylene glycol as a solvent to avoid the mass transfer resistance problem in the gas-liquid mixing process. Subsequent processes increase energy consumption in the separation process to achieve solvent recovery and reuse. Therefore, the improvement in process energy efficiency of this technology is limited compared with traditional processes. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of high reaction temperature, high reaction pressure, long reaction cycle, high safety risk, and increased energy consumption due to subsequent solvent separation and recovery in the synthesis of N-methylpyrrolidone in the prior art. This invention provides a microchannel reaction device and a method for preparing N-methylpyrrolidone. This invention has the advantages of not requiring the introduction of additional solvent, lower reaction pressure, and shorter reaction cycle, and can ensure high mixing reaction efficiency and good safety throughout the entire process.

[0007] To achieve the above objectives, the present invention provides a microchannel reaction apparatus, which includes a mixer having a liquid inlet and a reactor sealed and connected to the mixer, the reactor being provided with a product outlet;

[0008] The mixer includes a liquid phase fluid channel connected to the liquid phase inlet. The outer periphery of the liquid phase fluid channel is seamlessly wrapped with multiple layers of microscale sleeves. The outermost layer of the microscale sleeves is spaced around a mixer housing having at least one gas phase inlet. Each layer of the microscale sleeves has multiple through holes on its wall. The through holes in each layer are staggered at an angle, so that the through holes in each layer overlap to form a gradually decreasing gas phase channel. This channel is used to gradually shrink the gas phase raw material entering the mixer housing through each gas phase inlet to form microbubbles, which then enter the liquid phase fluid channel and dissolve and mix with the liquid phase raw material to form a homogeneous solution.

[0009] The reactor includes a reactor shell, within which multiple sets of grid microscale components are arranged without gaps parallel to the material flow direction. Each set of grid microscale components is formed by two identical grid microscale inserts stacked facing each other. Each grid microscale insert has multiple parallel slits along the material flow direction, and the slits of adjacent grid microscale inserts are staggered at an angle, so that the homogeneous solution from the mixer only passes through the overlapping part of the slits of adjacent grid microscale inserts, forming a tortuous reaction fluid path, so that the reactants are fully homogenized and reacted.

[0010] A second aspect of this invention provides a method for preparing N-methylpyrrolidone, which is carried out using the microchannel reaction apparatus described in this invention and includes the following steps:

[0011] 1) The gaseous raw material entering through the gaseous feed inlet flows through multiple layers of the microscale sleeve and is dispersed into microbubbles. It is then mixed with the liquid raw material entering through the liquid feed inlet in the liquid fluid channel to obtain a homogeneous solution under the mixing conditions, which is then fed into the reactor.

[0012] 2) The homogeneous solution described in step 1) flows and reacts between the slits of the multiple microscale inserts of the grid plates in the reactor, enhancing the contact efficiency between the gaseous raw material and the liquid reaction system, and obtaining the target product under the reaction conditions.

[0013] The gaseous raw material includes one or more of methylamine, dimethylamine, and trimethylamine, and the liquid raw material includes γ-butyrolactone.

[0014] Existing technologies use solvent dissolution, which still involves subsequent separation processing. The present invention, through the above-mentioned technical solution, does not use solvents and has no post-separation processing unit. Instead, it uses a mixer including a core component—a multi-layered stacked microscale sleeve with through holes—to increase solubility and reduce reaction pressure. The microchannel reaction device provided by the present invention utilizes the microscale effect to effectively enhance the gas-liquid dispersion performance in a multiphase flow system, enabling efficient dissolution of gaseous raw materials in liquid raw materials, thereby achieving an efficient, safe, and continuous reaction process.

[0015] This invention effectively limits the heat release of the reaction process while ensuring the gas-liquid mixing efficiency at a certain gas-liquid ratio by separately controlling the temperature, pressure, and gas-liquid ratio of the mixing and reaction processes, thereby matching the mixing and dissolution rate of the reaction system with the reaction progress. It has good applicability to heterogeneous reaction systems with large gas-liquid ratios and strong thermal effects, and can be used for continuous processes of various gas-liquid reaction systems. At the same time, it does not require the introduction of additional solvents to increase the energy consumption of subsequent separation sections. The effect is particularly obvious for the synthesis of N-methylpyrrolidone.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a microchannel reaction device according to a preferred embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of a mixer structure according to a preferred embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of a reactor structure according to a preferred embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures

[0021] 1 Liquid phase inlet; 2 Gas phase inlet; 3 Mixer; 4 Reactor; 5 Product outlet; 6 Mixing shell; 7 Porous microscale sleeve; 8 Liquid phase fluid channel; 9 Reactor shell; 10 Grid microscale insert; 11 Slit; 12 Through hole. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0023] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "left," and "right" generally refer to the upper, lower, left, and right positions shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer positions relative to the contours of each component itself. The hydraulic diameter in this invention refers to four times the ratio of the cross-sectional area to the perimeter, which is commonly used in the calculation of pipe resistance in chemical equipment. The equivalent diameter refers to a non-circular pipe diameter, which can be replaced by a circular pipe diameter, and is defined as: 4 * pipe cross-sectional area / wetting perimeter.

[0025] like Figure 1-3 As shown, the first aspect of the present invention provides a microchannel reaction device, which includes a mixer 3 having a liquid inlet 1 and a reactor 4 sealed and connected to the mixer 3, wherein the reactor 4 is provided with a product outlet 5;

[0026] The mixer 3 includes a liquid phase fluid channel 8 connected to the liquid phase inlet 1; the liquid phase fluid channel 8 is surrounded by multiple layers of microscale sleeves 7 without gaps, and the outermost layer of microscale sleeves 7 is surrounded by a mixer housing 6 with at least one gas phase inlet 2 with gaps. Multiple through holes 12 are opened on the wall of each layer of microscale sleeves 7, and the through holes 12 in each layer are staggered at an angle, so that the through holes 12 in each layer are stacked to form a gradually decreasing gas phase channel, which is used to gradually reduce the gas phase raw material entering the mixer housing 6 through each gas phase inlet 2 to form microbubbles, and enter the liquid phase fluid channel 8 to dissolve and mix with the liquid phase raw material to form a homogeneous solution;

[0027] The reactor 4 includes a reactor shell 9, within which multiple sets of grid microscale components are arranged without gaps parallel to the material flow direction. Each set of grid microscale components is formed by two identical grid microscale inserts 10 stacked facing each other. Each grid microscale insert 10 has multiple parallel slits 11 along the material flow direction, and the slits 11 of adjacent grid microscale inserts 10 are staggered at an angle, so that the homogeneous solution from the mixer 3 passes only through the overlapping part of the slits 11 of adjacent grid microscale inserts 10, forming a tortuous reaction fluid path, so that the reactants are fully homogenized and reacted.

[0028] In this invention, existing technology is used to seal the relevant interfaces of the mixer and reactor to form microchannels. Various pipelines or valves, as well as components that may be used in industry, can be added to each part as needed. This invention has no special requirements for this and will not be described in detail here.

[0029] Specifically, such as Figure 1-2 As shown, liquid raw materials enter the liquid fluid channel 8 through the liquid inlet 1, and gaseous raw materials enter the mixer shell 6 through at least one gas inlet 2, preferably two gas inlets 2. The gaseous raw materials then flow through the gaseous raw material channel formed by the through holes in the multi-layered inner and outer microscale sleeves 7, dispersing into microbubbles. These microbubbles then enter the liquid fluid channel and dissolve and mix with the liquid raw materials to form a homogeneous solution before flowing into the reactor 4 for reaction. In a preferred embodiment of the invention, the through holes on adjacent microscale sleeves 7 are machined at relatively staggered angles, so that adjacent... The through holes between the two layers do not completely overlap, but the overlapping of multiple layers of staggered through holes 12 gradually reduces the overall overlap between the through holes, forming a gas phase raw material channel to gradually disperse the gas phase raw material into tiny bubbles; by increasing the dispersion of the gas phase raw material, the contact area between the gas and liquid phases is increased, the mass transfer resistance is reduced, and the safety risk is lowered; of course, in order to form a gradually decreasing gas phase raw material channel, in another preferred embodiment of the present invention, the through holes of each layer of microscale sleeve 7 can also be made to overlap, ensuring that the size of each layer of through hole 12 decreases from the outer layer to the inner layer.

[0030] In this invention, the reactor shell and the edges of each of the microscale grid plate inserts 10 inside it are fitted together without gaps, and adjacent microscale grid plate inserts 10 (here, the two microscale grid plate inserts are exactly the same; for ease of understanding, for example...) Figure 3 The grid microscale components, as shown in the diagram, are stacked facing each other according to the orientation of the slit openings (styles 10a and 10b). This allows the homogeneous solution from the mixer 3 to pass through only the overlapping portion of the slits 11 of the two adjacent grid microscale inserts 10, forming a tortuous reaction fluid path that eventually fills the entire reactor, ensuring that the reactants are fully homogenized and reacted.

[0031] Existing technologies use solvent dissolution, which still involves subsequent separation processing. The present invention, through the above-mentioned technical solution, does not use solvents and has no post-separation processing unit. Instead, it uses a mixer including a core component—a multi-layered stacked microscale sleeve with through holes—to increase solubility and reduce reaction pressure. The microchannel reaction device provided by the present invention utilizes the microscale effect to effectively enhance the gas-liquid dispersion performance in a multiphase flow system, enabling efficient dissolution of gaseous raw materials in liquid raw materials, thereby achieving an efficient, safe, and continuous reaction process.

[0032] This invention effectively limits the heat release of the reaction process while ensuring the gas-liquid mixing efficiency at a certain gas-liquid ratio by separately controlling the temperature, pressure, and gas-liquid ratio of the mixing and reaction processes, thereby matching the mixing and dissolution rate of the reaction system with the reaction progress. It has good applicability to heterogeneous reaction systems with large gas-liquid ratios and strong thermal effects, and can be used for continuous processes of various gas-liquid reaction systems. At the same time, it does not require the introduction of additional solvents to increase the energy consumption of subsequent separation sections. The effect is particularly obvious for the synthesis of N-methylpyrrolidone.

[0033] The apparatus of the present invention is particularly suitable for gas-liquid two-phase contact reactions with a gas-liquid molar ratio of 5 or higher.

[0034] According to a preferred embodiment of the present invention, the equivalent diameter of the mixer housing 6 is 5-12cm, preferably 6-10cm, and the length is 10-20cm, preferably 12-16cm.

[0035] According to a preferred embodiment of the present invention, the number of layers of the microscale sleeve 7 in the mixer 3 is 5-20, preferably 8-12.

[0036] According to a preferred embodiment of the present invention, preferably, the microscale sleeve 7 is a cylindrical annular piece, more preferably, the thickness of the microscale sleeve 7 is 4-12 mm, and even more preferably 4-8 mm.

[0037] According to a preferred embodiment of the present invention, the hydraulic diameter of the liquid phase fluid channel 8 is 200-800 μm, preferably 400-600 μm, and the length of the liquid phase fluid channel 8 is the same as the length of the mixer housing 6. It should be noted that a filter membrane is provided inside the liquid phase fluid channel 8, which allows gas to pass through while preventing liquid from passing through. This is prior art well known to those skilled in the art, and will not be described in detail here.

[0038] According to a preferred embodiment of the present invention, the opening ratio on the wall of the microscale sleeve 7 is 30-90%, preferably 60-80%.

[0039] According to a preferred embodiment of the present invention, preferably, the staggered angle between the through holes 12 in each layer is 5-10°, more preferably 6-8°.

[0040] According to a preferred embodiment of the present invention, the through hole 12 is a racetrack-shaped hole composed of a central rectangle and two semicircles on both sides.

[0041] According to a preferred embodiment of the present invention, preferably, the long axis of the through hole 12 is 20-200 μm, more preferably 60-120 μm.

[0042] According to a preferred embodiment of the present invention, preferably, the short axis of the through hole 12 is 10-80 μm, more preferably 20-40 μm.

[0043] According to a preferred embodiment of the present invention, the equivalent diameter of the reactor shell 9 is 5-12cm, preferably 6-10cm, and the length is 20-40cm, preferably 24-32cm.

[0044] According to a preferred embodiment of the present invention, the number of layers of the grid microscale insert 10 is 50-200 layers, preferably 70-90 layers.

[0045] like Figure 3 As shown, according to a preferred embodiment of the present invention, preferably, the microscale insert 10 of the grid plate is a rectangular thin sheet, more preferably, the thickness of the microscale insert 10 of the grid plate is 0.4-1mm, and even more preferably 0.4-0.8mm.

[0046] According to a preferred embodiment of the present invention, the slit 11 provided in each of the microscale inserts 10 of the grid plate consists of two identical parallelogram holes, one end of the two parallelogram holes being close to each other but not connected, and the other end being far apart from each other.

[0047] According to a preferred embodiment of the present invention, preferably, the slits of two adjacent microscale inserts 10 of the grid plate are staggered by an angle of 5-10°, more preferably 6-8°. Similarly, the slits of two adjacent layers are staggered by an angle during processing.

[0048] According to a preferred embodiment of the present invention, preferably, the interval between two adjacent slits 11 on the microscale insert 10 of the grid plate is 5-50 μm, and more preferably 10-30 μm.

[0049] According to a preferred embodiment of the present invention, preferably, the length of the slit 11 is 1-8cm, more preferably 2-6cm;

[0050] According to a preferred embodiment of the present invention, preferably, the width of each of the parallelogram holes is 5-50 μm, more preferably 10-30 μm; preferably, the parallelogram holes have an inclination angle, more preferably 10-80°, and even more preferably 15-45°.

[0051] According to a preferred embodiment of the present invention, the liquid phase inlet 1 and the gas phase inlet 2 have the same hydraulic diameter, preferably 1000-3000 μm, more preferably 1500-2000 μm.

[0052] According to a preferred embodiment of the present invention, preferably, the extension line of each of the gas phase inlets 2 forms an angle with the extension line of the liquid phase inlets 1, more preferably the angle is 15-90°, and even more preferably 30-60°.

[0053] According to a preferred embodiment of the present invention, the hydraulic diameter of the product outlet 5 is 200-800 μm, preferably 400-600 μm.

[0054] According to a preferred embodiment of the present invention, the materials of the liquid inlet 1, the gas inlet 2, the mixer 3, the reactor 4 and the product outlet 5 are selected from one or more of metals, alloys and ceramics, preferably selected from one or more of stainless steel 316L, Hastelloy C and silicon carbide ceramics.

[0055] A second aspect of this invention provides a method for preparing N-methylpyrrolidone, which is carried out using the microchannel reaction apparatus described in this invention and includes the following steps:

[0056] 1) The gaseous raw material entering through the gaseous feed inlet 2 flows through the multi-layer microscale sleeve 7 and is dispersed into microbubbles. It mixes with the liquid raw material entering through the liquid feed inlet 1 in the liquid fluid channel 8. Under the mixing conditions, a homogeneous solution is obtained and sent to the reactor 4.

[0057] 2) The homogeneous solution described in step 1) flows and reacts between the slits of the multiple microscale inserts 10 of the grid plates in the reactor 4, which enhances the contact efficiency between the gaseous raw materials and the liquid reaction system, and the target product is obtained under the reaction conditions.

[0058] The gaseous raw material includes one or more of methylamine, dimethylamine, and trimethylamine, and the liquid raw material includes γ-butyrolactone.

[0059] Existing technologies use solvent dissolution, which requires subsequent separation processing. This invention, however, does not use solvents and eliminates the need for a post-separation unit. A mixer 3, comprising a core component—a multi-layered, stacked microscale sleeve 7 with through-holes—disperses the gaseous raw material into microbubbles. By increasing the dispersion of the gaseous raw material, the contact area between the gas and liquid phases is increased, thereby increasing solubility and reducing reaction pressure.

[0060] This invention effectively limits the heat release of the reaction process while ensuring the gas-liquid mixing efficiency at a certain gas-liquid ratio by separately controlling the temperature, pressure, and gas-liquid ratio of the mixing and reaction processes, thereby matching the mixing and dissolution rate of the reaction system with the reaction progress. It has good applicability to heterogeneous reaction systems with large gas-liquid ratios and strong thermal effects, and can be used for continuous processes of various gas-liquid reaction systems. At the same time, it does not require the introduction of additional solvents to increase the energy consumption of subsequent separation sections. The effect is particularly obvious for the synthesis of N-methylpyrrolidone.

[0061] The method of the present invention is particularly suitable for gas-liquid two-phase contact reactions with a gas-liquid molar ratio of 5 or higher.

[0062] According to a preferred embodiment of the present invention, the mixing conditions include: a mixing temperature of 10-50°C, a mixing pressure of 1-3 MPa, and a residence time of 1-10 min.

[0063] According to a preferred embodiment of the present invention, the reaction conditions include: a reaction temperature of 200-350°C, a reaction pressure of 2-4 MPa, and a residence time of 10-30 min.

[0064] The present invention will be further illustrated below with reference to embodiments and comparative examples, but the apparatus and method of the present invention are not limited thereto.

[0065] The apparatus and method of the present invention will be further described below with reference to embodiments.

[0066] Example 1

[0067] (1) According to Figures 1-3 The device is set up as shown:

[0068] The main body of the microchannel reactor is made of 316L stainless steel. Micron-scale structures are precision-machined onto the stainless steel substrate. In the mixer 3 and reactor 4, microscale sleeves 7 and grid microscale inserts 10 are stacked in multiple layers using concentric rings and alternating plates, respectively. After sealing the relevant interfaces, the liquid phase fluid channel 8 of the mixer is formed. The specific arrangement and dimensions are as follows: the hydraulic diameter of the liquid phase inlet 1 is 1000 μm; the hydraulic diameter of the gas phase inlet 2 is 1000 μm, and the included angle between them is 30°; the hydraulic diameter of the product outlet 5 is 800 μm; the equivalent diameter of the mixer shell 6 is 10 cm, and its length is 20 cm. The hydraulic diameter of the liquid phase fluid channel is 500 μm; the thickness of the microscale sleeve is 4 mm, the number of layers is 10, the major axis of the through hole 12 is 120 μm, the minor axis is 60 μm, the opening rate is 75%, and the positioning angle between each layer is 8°; the equivalent diameter of the reactor shell 9 is 10 cm, and the length is 40 cm; the thickness of the grid microscale insert 10 is 0.8 mm, the number of layers is 100; the slit spacing of the grid microscale insert is 20 μm, the slit length is 3 cm, the width of each parallelogram hole constituting the slit 11 is 30 μm, the inclination angle of the parallelogram hole is 30°, and the angle between each layer of slits is 8°.

[0069] Reference Figure 1 The microchannel reactor shown synthesizes N-methylpyrrolidone. Different modules of the microreactor are temperature-controlled by an independent integrated heating and cooling unit. Crude N-methylpyrrolidone can be collected from the product outlet.

[0070] (2) Synthesis of 2N-methylpyrrolidone: A metering pump was used to deliver liquid raw material γ-butyrolactone, which entered mixer 3 through liquid inlet 1. A mass flow meter was used to deliver gaseous raw material methylamine, which entered the mixer in equal amounts through two gas inlets 2. The molar flow ratio of the main raw materials in the metering pump and mass flow meter was set to methylamine:γ-butyrolactone = 1.2:1. The three materials were fully contacted in mixer 3 and then entered reactor 4 for condensation reaction. The temperature of the mixer was controlled at 20℃ and the pressure at 2.0MPa, and the temperature of the reactor was controlled at 240℃ and the reaction pressure at 1.0MPa. The mixing residence time of the reactants was controlled to 5 min by adjusting the flow rates of the metering pump and the mass flow meter, and the reaction residence time was controlled to 25 min. The material at the final liquid product outlet 5 of the microchannel reactor was crude N-methylpyrrolidone. Product analysis results showed that the conversion rate of γ-butyrolactone was 95.3%, and the selectivity of N-methylpyrrolidone was 99.4%.

[0071] Example 2

[0072] All steps in this embodiment are basically the same as in Embodiment 1. The difference is that the hydraulic diameter of the liquid phase fluid channel 8 in this embodiment is 1000 μm, the thickness of the microscale sleeve 7 is 3.75 mm, and the number of layers is 10. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 92.1%, and the selectivity of N-methylpyrrolidone is 99.6%.

[0073] Example 3

[0074] All steps in this embodiment are basically the same as in Embodiment 1. The difference is that the hydraulic diameter of the liquid phase fluid channel 8 in this embodiment is 200 μm, the thickness of the microscale sleeve is 4.25 mm, and the number of layers is 10. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 95.9%, and the selectivity of N-methylpyrrolidone is 98.8%.

[0075] Example 4

[0076] All steps in this embodiment are basically the same as in Example 1. The difference is that in this embodiment, the major axis of the through hole 12 is 200 μm and the minor axis is 100 μm. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 89.1% and the selectivity of N-methylpyrrolidone is 99.3%.

[0077] Example 5

[0078] All steps in this embodiment are basically the same as in Example 1. The difference is that the major axis of the through hole 12 in this embodiment is 80 μm and the minor axis is 40 μm. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 96.1% and the selectivity of N-methylpyrrolidone is 98.4%.

[0079] Example 6

[0080] All steps in this embodiment are basically the same as in Embodiment 1. The difference is that the thickness of the microscale plug-in 10 of the grid plate in this embodiment is 1.0 mm and the number of layers is 80. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 85.1% and the selectivity of N-methylpyrrolidone is 99.6%.

[0081] Example 7

[0082] All steps in this embodiment are basically the same as in Embodiment 1. The difference is that the thickness of the microscale plug-in 10 of the grid plate in this embodiment is 0.4 mm and the number of layers is 200. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 96.6% and the selectivity of N-methylpyrrolidone is 98.3%.

[0083] Example 8

[0084] All steps in this embodiment are basically the same as in Embodiment 1. The difference is that in this embodiment, the slit spacing of the grid microscale plug-in 10 is 40 μm, and the width of each parallelogram hole is 60 μm. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 81.9%, and the selectivity of N-methylpyrrolidone is 99.4%.

[0085] Example 9

[0086] All steps in this embodiment are basically the same as in Embodiment 1. The difference is that in this embodiment, the slit spacing of the microscale plug-in 10 of the grid plate is 10 μm, and the width of each parallelogram hole is 20 μm. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 95.9%, and the selectivity of N-methylpyrrolidone is 98.5%.

[0087] Example 10

[0088] All steps in this embodiment are basically the same as in Example 1. The difference is that the temperature of the reactor in this embodiment is 280°C. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 98.9%, and the selectivity of N-methylpyrrolidone is 91.4%.

[0089] Example 11

[0090] All steps in this embodiment are basically the same as in Example 1. The difference is that the temperature of the reactor in this embodiment is 200°C. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 93.2%, and the selectivity of N-methylpyrrolidone is 99.8%.

[0091] Example 12

[0092] All steps in this embodiment are basically the same as in Example 1. The difference is that the pressure of the reactor in this embodiment is 2.0 MPa. The product analysis results show that the conversion rate of γ-butyrolactone during the reaction is 96.2%, and the selectivity of N-methylpyrrolidone is 99.0%.

[0093] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. The present invention will not further describe the various possible combinations. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A microchannel reaction device, characterized in that, The device includes a mixer (3) having a liquid inlet (1) and a reactor (4) that is sealed in communication with the mixer (3), the reactor (4) being provided with a product outlet (5). The mixer (3) includes a liquid phase fluid channel (8) that connects to the liquid phase feed port (1). The liquid phase fluid channel (8) is surrounded by multiple layers of microscale sleeves (7) without gaps. The outermost microscale sleeve (7) is surrounded by a mixer housing (6) with at least one gas phase feed port (2) with gaps. Multiple through holes (12) are opened on the wall of each layer of microscale sleeve (7). The through holes (12) of each layer are staggered at an angle so that the through holes (12) of each layer are stacked to form a gradually decreasing gas phase channel, which is used to gradually shrink the gas phase raw material entering the mixer housing (6) through each gas phase feed port (2) to form microbubbles, which enter the liquid phase fluid channel (8) and dissolve and mix with the liquid phase raw material to form a homogeneous solution. The reactor (4) includes a reactor shell (9), in which multiple sets of grid microscale components are arranged without gaps in parallel with the material flow direction. Each set of grid microscale components is formed by two identical grid microscale inserts (10) stacked facing each other. Each grid microscale insert (10) is provided with multiple parallel slits (11) along the material flow direction. The slits (11) of two adjacent grid microscale inserts (10) are staggered at an angle, so that the homogeneous solution from the mixer (3) only passes through the overlapping part of the slits (11) of two adjacent grid microscale inserts (10), forming a tortuous reaction fluid path, so that the reactants are fully homogenized and reacted.

2. The reaction apparatus according to claim 1, wherein, The equivalent diameter of the mixer housing (6) is 5-12 cm; the length is 10-20 cm; and / or The number of layers of the microscale sleeve (7) inside the mixer (3) is 5-20.

3. The reaction apparatus according to claim 2, wherein, The equivalent diameter of the mixer housing (6) is 6-10 cm; and / or The number of layers of the microscale sleeve (7) inside the mixer (3) is 8-12.

4. The reaction apparatus according to claim 2, wherein, The microscale sleeve (7) is a cylindrical annular plate; and / or The hydraulic diameter of the liquid phase fluid channel (8) is 200-800 μm, and the length of the liquid phase fluid channel (8) is the same as the length of the mixer housing (6).

5. The reaction apparatus according to claim 2, wherein, The thickness of the microscale sleeve (7) is 4-12 mm; and / or The hydraulic diameter of the liquid phase fluid channel (8) is 400-600 μm.

6. The reaction apparatus according to claim 2, wherein, The thickness of the microscale sleeve (7) is 4-8 mm.

7. The reaction apparatus according to claim 1, wherein, The opening ratio on the wall of the microscale sleeve (7) is 30-90%.

8. The reaction apparatus according to claim 7, wherein, The opening ratio on the wall of the microscale sleeve (7) is 60-80%.

9. The reaction apparatus according to claim 7, wherein, The through holes (12) in each layer are staggered by an angle of 5-10°; and / or The through hole (12) is a racetrack-shaped hole with a central rectangle and semicircles on both sides.

10. The reaction apparatus according to claim 7, wherein, The through holes (12) in each layer are staggered by an angle of 6-8°.

11. The reaction apparatus according to claim 7, wherein, The major axis of the through hole (12) is 20-200 μm.

12. The reaction apparatus according to claim 7, wherein, The major axis of the through hole (12) is 60-120 μm.

13. The reaction apparatus according to claim 7, wherein, The short axis of the through hole (12) is 10-80 μm.

14. The reaction apparatus according to claim 7, wherein, The minor axis of the through hole (12) is 20-40 μm.

15. The reaction apparatus according to claim 1, wherein, The equivalent diameter of the reactor shell (9) is 5-12 cm, and the length is 20-40 cm; and / or The number of layers in the microscale plug-in (10) of the grid plate is 50-200.

16. The reaction apparatus according to claim 15, wherein, The equivalent diameter of the reactor shell (9) is 6-10 cm, and the length is 24-32 cm; and / or The number of layers in the microscale plug-in (10) of the grid plate is 70-90.

17. The reaction apparatus according to claim 15, wherein, The microscale insert (10) of the grid plate is a rectangular thin sheet.

18. The reaction apparatus according to claim 15, wherein, The thickness of the microscale insert (10) of the grid plate is 0.4-1mm.

19. The reaction apparatus according to claim 15, wherein, The thickness of the microscale insert (10) of the grid plate is 0.4-0.8 mm.

20. The reaction apparatus according to claim 1, wherein, The slit (11) provided in each of the microscale inserts (10) of the grid plate consists of two identical parallelogram holes, one end of which is close to each other but not connected, and the other end is far from each other.

21. The reaction apparatus according to claim 20, wherein, The slits of two adjacent microscale inserts (10) of the grid are staggered by an angle of 5-10°.

22. The reaction apparatus according to claim 20, wherein, The slits of two adjacent microscale inserts (10) of the grid are staggered by an angle of 6-8°.

23. The reaction apparatus according to claim 20, wherein, The two adjacent slits (11) located on the microscale insert (10) of the grid are spaced 5-50 μm apart.

24. The reaction apparatus according to claim 20, wherein, The two adjacent slits (11) located on the microscale insert (10) of the grid plate are spaced 10-30 μm apart.

25. The reaction apparatus according to claim 20, wherein, The slit (11) is 1-8 cm long.

26. The reaction apparatus according to claim 20, wherein, The slit (11) is 2-6 cm long.

27. The reaction apparatus according to claim 20, wherein, The width of each of the parallelogram holes is 5-50 μm.

28. The reaction apparatus according to claim 20, wherein, The width of each of the parallelogram holes is 10-30 μm.

29. The reaction apparatus according to claim 20, wherein, The parallelogram-shaped hole has an angle.

30. The reaction apparatus according to claim 29, wherein, The tilt angle is 10-80°.

31. The reaction apparatus according to claim 29, wherein, The tilt angle is 15-45°.

32. The reaction apparatus according to claim 1, wherein, The liquid phase inlet (1) has the same hydraulic diameter as the gas phase inlet (2).

33. The reaction apparatus according to claim 32, wherein, The hydraulic diameters of the liquid inlet (1) and the gas inlet (2) are 1000-3000 μm.

34. The reaction apparatus according to claim 32, wherein, The hydraulic diameters of the liquid inlet (1) and the gas inlet (2) are 1500-2000 μm.

35. The reaction apparatus according to claim 32, wherein, The extension line of each of the gas phase inlets (2) forms an angle with the extension line of the liquid phase inlets (1).

36. The reaction apparatus according to claim 35, wherein, The included angle is 15-90°.

37. The reaction apparatus according to claim 35, wherein, The included angle is 30-60°.

38. The reaction apparatus according to claim 1, wherein, The hydraulic diameter of the product outlet (5) is 200-800 μm.

39. The reaction apparatus according to claim 38, wherein, The hydraulic diameter of the product outlet (5) is 400-600 μm.

40. The reaction apparatus according to any one of claims 1-39, wherein, The materials of the liquid inlet (1), the gas inlet (2), the mixer (3), the reactor (4), and the product outlet (5) are selected from one or both of metal and ceramic.

41. The reaction apparatus according to claim 40, wherein, The materials of the liquid phase inlet (1), the gas phase inlet (2), the mixer (3), the reactor (4), and the product outlet (5) are selected from one or more of stainless steel 316L, Hastelloy C, and silicon carbide ceramics.

42. A method for preparing N-methylpyrrolidone, characterized in that, This method is implemented using the microchannel reaction apparatus according to any one of claims 1-41, and includes the following steps: 1) The gaseous raw material entering through the gaseous feed port (2) flows through the multi-layer microscale sleeve (7) and is dispersed into microbubbles. It mixes with the liquid raw material entering through the liquid feed port (1) in the liquid fluid channel (8) to obtain a homogeneous solution under the mixing conditions and then feeds it into the reactor (4). 2) The homogeneous solution described in step 1) flows and reacts between the slits of the multiple microscale inserts (10) of the grid plate in the reactor (4), which enhances the contact efficiency between the gaseous raw material and the liquid reaction system, and the target product is obtained under the reaction conditions. The gaseous raw material includes one or more of methylamine, dimethylamine, and trimethylamine, and the liquid raw material includes γ-butyrolactone.

43. The method according to claim 42, wherein, The mixing conditions include: a mixing temperature of 10-50℃, a mixing pressure of 1-3MPa, and a residence time of 1-10min; and / or The reaction conditions include: a reaction temperature of 200-350℃, a reaction pressure of 2-4MPa, and a residence time of 10-30min.

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