Microchannel reactor device, its use and process for the preparation of n-vinylpyrrolidone

Abstract

The application relates to the technical field of micro-channel reaction devices, and discloses a micro-channel reaction device, application thereof and a preparation method of N-vinyl pyrrolidone, which comprises multiple groups of mixed modules and reaction modules in series, multiple layers of nested cross-flow mixing structures are arranged in the mixed modules, liquid-phase raw materials and gas-phase raw materials are mixed in the mixed modules, and then enter the reaction modules; multiple layers of nested cross-flow mixing structures are arranged in the reaction modules, the reaction raw materials are reacted in the reaction modules, then enter the next-stage mixed modules, are mixed with supplemented gas-phase raw materials, and then continue to react, and the target product crude product is obtained after multi-stage reaction. The micro-channel reaction device can effectively strengthen the process of a multiphase flow reaction system by using micro-scale effects, can provide a multi-stage distributed feeding solution for the problem of excessively high gas-liquid ratio in a large gas-liquid ratio reaction system, and can guarantee efficient mixing reaction efficiency and good safety in the whole technological process.

Description

Technical Field

[0001] This invention belongs to the technical field of microchannel reaction devices, specifically relating to a microchannel reaction device and its application in gas-liquid two-phase contact reactions, and a method for preparing N-vinylpyrrolidone. Background Technology

[0002] Microchannel technology is a process intensification technique based on complex three-dimensional structures at the micrometer scale for chemical reactions, heat exchange, mixing, and separation. It can effectively improve the heat and mass transfer efficiency and space energy utilization in chemical processes, achieving precise control of reaction conditions under intrinsically safe conditions. In recent years, due to its ability to achieve high-efficiency conversion and continuous production, microchannel reaction technology has shown significant advantages and broad application prospects compared to traditional batch reactor processes in the synthesis of fine chemicals with severe thermal effects, leading to rapid development in the fields of fine chemicals and pharmaceutical chemicals.

[0003] However, many heterogeneous processes exist in chemical processes. Such production processes often include multiple processes such as heat transfer, mixing, reaction, separation, and even external field enhancement. Existing continuous flow synthesis technology does not have very mature commercial products and process routes for multi-process coupling in heterogeneous systems.

[0004] CN101391974A discloses a method for continuous flow synthesis of N-vinylpyrrolidone. It utilizes the metal membrane tube material of a membrane dispersion reactor to enhance gas-liquid mixing efficiency. However, the distributor made of the metal membrane tube material is only placed below the reactor, and there is a lack of micro-scale restriction on the upper part of the reactor after fluid contact. Therefore, the gaseous feedstock can easily form large-scale bubbles above the reactor through collision and aggregation. Thus, the improvement in process efficiency and safety of this reactor compared with traditional processes is limited. Summary of the Invention

[0005] To address the limited improvement in process efficiency and safety of existing microchannel reactors compared to traditional processes, this invention provides a microchannel reaction device and its application, as well as a method for preparing N-vinylpyrrolidone. This device can efficiently dissolve gaseous raw materials in liquid raw materials, achieving a highly efficient, safe, and continuous reaction process under high temperature and pressure.

[0006] To achieve the above objectives, the present invention provides a microchannel reaction device, comprising a multi-stage continuous reaction channel, wherein the multi-stage continuous reaction channel is formed by continuously alternating series of mixing modules and reaction modules, and the two ends of the multi-stage continuous reaction channel are respectively connected to a liquid phase raw material inlet and a product outlet. Each stage of the mixing module is provided with a gas phase raw material inlet for feeding the gaseous raw material into the mixing module of each stage in multiple streams.

[0007] Each mixing module includes a shell connected to the gaseous raw material inlet and a cross-flow microscale structure with a liquid phase mixing channel disposed within the shell. The liquid phase mixing channel is connected to the liquid raw material inlet, and multiple micropores are formed on the wall of the cross-flow microscale structure, so that the gaseous raw material enters the liquid phase mixing channel through the micropores and dissolves and mixes with the liquid raw material to form a homogeneous solution.

[0008] The reaction module includes a sleeve, a concentric shaft disposed within the sleeve, and a cross microscale structure disposed between the sleeve and the concentric shaft. Multiple slits are formed on the wall of the cross microscale structure. The diameter of the concentric shaft is smaller than that of the liquid phase mixing channel, so that the homogeneous solution flows into the multiple slits and reacts in the reaction module.

[0009] A second aspect of the present invention provides the application of the reaction apparatus described herein in gas-liquid two-phase contact reactions; preferably comprising:

[0010] 1) The gaseous feedstock and the liquid feedstock are mixed in the primary mixing module to obtain a primary homogeneous solution under the mixing conditions, which is then sent to the primary reaction module;

[0011] 2) Under the reaction conditions, the primary homogeneous solution is reacted in the primary reaction module to obtain the primary discharge, which is then sent to the secondary mixing module;

[0012] 3) The gaseous raw material supplemented through the secondary gaseous raw material inlet is mixed with the primary effluent from step 2) in the secondary mixing module to obtain a secondary homogeneous solution under mixing conditions, and then sent to the secondary reaction module to obtain a secondary effluent under reaction conditions;

[0013] Similarly, the material discharged from the previous stage reaction module enters the next stage mixing module and is mixed with the supplemented gaseous raw material to continue the reaction until the liquid phase raw material conversion rate reaches the target value and is then collected by the product outlet. The liquid phase raw material includes raw materials, catalysts and optional catalyst additives.

[0014] A third aspect of this invention provides a method for preparing N-vinylpyrrolidone, which is implemented using the microchannel reaction device described in this invention. The liquid-phase raw material is fed into a primary mixing module in one step, and each mixing module is equipped with an inlet for the gas-phase raw material, allowing for segmented feeding of the gas-phase raw material. The method includes the following steps:

[0015] 1) The gaseous feedstock and the liquid feedstock are mixed in the primary mixing module to obtain a primary homogeneous solution under the mixing conditions, which is then sent to the primary reaction module;

[0016] 2) Under the reaction conditions, the primary homogeneous solution is reacted in the primary reaction module to obtain the primary discharge, which is then sent to the secondary mixing module;

[0017] 3) The gaseous raw material supplemented through the secondary gaseous raw material inlet is mixed with the primary effluent from step 2) in the secondary mixing module to obtain a secondary homogeneous solution under mixing conditions, and then sent to the secondary reaction module to obtain a secondary effluent under reaction conditions;

[0018] In this manner, the output from the previous stage reaction module enters the next stage mixing module and is mixed with the supplemented gaseous raw materials to continue the reaction until the conversion rate of the liquid raw materials reaches the target value, at which point it is collected from the product outlet.

[0019] The gaseous raw material includes a raw material gas and a protective gas. The raw material gas is acetylene, and the protective gas is selected from one or more of nitrogen, argon, helium, carbon dioxide, and low-carbon alkanes.

[0020] The liquid-phase raw material includes a raw material, a catalyst, and an optional catalyst promoter. The raw material is α-pyrrolidone, the catalyst is potassium pyrrolidone, and the catalyst promoter is polytetrahydrofuran.

[0021] This invention constructs a multi-stage coupled mixing-reaction process, which is particularly suitable for gas-liquid ratio reaction processes. It allows for separate control of temperature, pressure, and gas-liquid ratio conditions in both the mixing and reaction processes, matching the mixing and dissolution rate of the reaction system with the reaction progress of each stage. This effectively limits the heat release of the reaction process while ensuring gas-liquid mixing efficiency under a certain gas-liquid ratio. It has good applicability to heterogeneous reaction systems with a gas-liquid ratio and strong thermal effects, and can be used for continuous processes of various gas-liquid reaction systems. The effect is particularly significant for the acetylene-based synthesis of NVP.

[0022] Through the above technical solution, the microchannel reaction device provided by the present invention effectively restricts the bubble size of gaseous raw materials in multiphase fluids throughout the process by utilizing the microscale effect, so as to dissolve the gaseous raw materials in the liquid raw materials as efficiently as possible, thereby achieving an enhanced, efficient, safe and continuous reaction process under high temperature and high pressure.

[0023] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0024] Figure 1 This is an overall schematic diagram of a microchannel reaction device according to a preferred embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of a hybrid module structure according to a preferred embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the reaction module structure according to a preferred embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] 1 Liquid phase feed inlet; 2 Gas phase feed inlet; 3 Mixing module; 31 Shell; 4 Reaction module; 41 Sleeve; 5 Product outlet; 6 Liquid phase mixing channel; 7 Cross-flow microscale structure; 8 Micropore; 9 Concentric shaft; 10 Cross-shaped microscale structure; 11 Slit. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "left," and "right" generally refer to the upper, lower, left, and right as shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer 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, and is often used in the calculation of pipeline resistance in chemical equipment.

[0032] like Figure 1-3 As shown, the first aspect of the present invention provides a microchannel reaction device, which includes a multi-stage continuous reaction channel. The multi-stage continuous reaction channel is formed by continuously alternating series connection of a mixing module 3 and a reaction module 4. The two ends of the multi-stage continuous reaction channel are respectively connected to a liquid phase raw material inlet 1 and a product outlet 5. Each mixing module 3 is provided with a gas phase raw material inlet 2 for feeding the gas raw material into the mixing module 3 of each stage in multiple streams.

[0033] Each mixing module 3 includes a housing 31 connected to the gaseous raw material inlet 2 and a cross-flow microscale structure 7 with a liquid phase mixing channel 6 disposed in the housing 31. The liquid phase mixing channel 6 is connected to the liquid raw material inlet 1. Multiple micropores 8 are formed on the wall of the cross-flow microscale structure 7, so that the gaseous raw material enters the liquid phase mixing channel 6 through the micropores 8 and dissolves and mixes with the liquid raw material to form a homogeneous solution.

[0034] The reaction module 4 includes a sleeve 41, a concentric shaft 9 disposed inside the sleeve 41, and a cross microscale structure 10 disposed between the sleeve 41 and the concentric shaft 9. The cross microscale structure 10 has multiple slits 11 on its wall. The diameter of the concentric shaft 9 is smaller than that of the liquid phase mixing channel 6, so that the homogeneous solution flows into the multiple slits 11 and reacts in the reaction module 4.

[0035] In this invention, existing technology is used to seal the relevant interfaces of alternating series mixing modules and reaction modules to form the fluid channel of a micro mixer. Various pipelines or valves, as well as components that may be used in industry, can be added to each module as needed. This invention has no special requirements for this and will not be described in detail here.

[0036] It should be noted that in this invention, the liquid raw material is fed axially into the liquid mixing channel 6 through the liquid raw material inlet 1. The gaseous raw material enters the shell 31 through the gaseous raw material inlet 2. There is a radial gap between the shell 31 and the cross-flow microscale structure 7. The gaseous raw material flows radially into the liquid mixing channel 6 through the micropores 8 on the cross-flow microscale structure 7. After mixing and dissolving with the liquid raw material to form a homogeneous solution, it enters the reaction module 4. The cross-microscale structure 10 can disrupt the normal flow direction of the homogeneous solution, so that the homogeneous solution reacts in a state of flow and mixing between the concentric axis 9 and the cross-microscale structure 10. As is known to those skilled in the art, during the reaction, part of the raw material gas reacts rapidly to generate the target product, while part of the raw material gas will escape along with the protective gas due to the increase in temperature. The cross-microscale structure in this invention enables the reaction system to react in a mixed state, which can greatly improve the reaction efficiency.

[0037] Furthermore, it is understood that the mixing-reaction process of the present invention is completed in different modules. Therefore, each mixing module 3 and reaction module 4 of the present invention can be equipped with a temperature control device for precise control of the dissolution, mixing and catalytic reaction of the gas-liquid reaction system in different temperature regions. Based on this, the present invention can also cool the reaction system to a certain temperature and then enter the next mixing module 3 for re-dissolution, and then enter the next reaction module 4 to continue the reaction. This process is carried out alternately until the liquid phase raw material conversion rate reaches the target value and is then collected from the product outlet 5.

[0038] This invention constructs a multi-stage coupled mixing-reaction process, which is particularly suitable for gas-liquid ratio reaction processes. It allows for separate control of temperature, pressure, and gas-liquid ratio conditions in both the mixing and reaction processes, matching the mixing and dissolution rate of the reaction system with the reaction progress of each stage. This effectively limits the heat release of the reaction process while ensuring gas-liquid mixing efficiency under a certain gas-liquid ratio. It has good applicability to heterogeneous reaction systems with a gas-liquid ratio and strong thermal effects, and can be used for continuous processes of various gas-liquid reaction systems. The effect is particularly significant for the acetylene-based synthesis of NVP.

[0039] The apparatus of the present invention is particularly suitable for gas-liquid two-phase contact reactions with a gas-liquid molar ratio of 10 or higher.

[0040] To achieve better mixing of gaseous and liquid feedstocks, such as Figure 2 As shown, according to a preferred embodiment of the present invention, multiple layers of the cross-flow microscale structure 7 are provided inside the shell 31. Each layer is coaxially fixed without gaps and staggered at a certain angle, so that the micropores 8 of each layer overlap to form gradually decreasing gas phase raw material channels, so that the gas phase raw material forms micro bubbles and dissolves and mixes with the liquid phase raw material to form a homogeneous solution. It should be noted that the cross-flow microscale structure 7 is coaxially fixed without gaps, so that each layer of micropores 8 overlaps to form a gas phase raw material channel, and the staggered angle reduces the intersection between the micropores 8 of each layer to form a gradually decreasing gas phase raw material channel, thereby achieving the purpose of dividing the gas phase raw material into small bubbles. It can be understood that controlling the size of the staggered angle between each layer can control the size of the bubbles.

[0041] According to a preferred embodiment of the present invention, preferably, the number of layers in the crossflow microscale structure is 5-10 layers, more preferably 7-9 layers.

[0042] According to a preferred embodiment of the present invention, preferably, the offset angle between two adjacent layers of the crossflow microscale structure 7 is 5-10°, more preferably 6-8°.

[0043] According to a preferred embodiment of the present invention, preferably, the diameter of the shell 31 is 5-27cm, more preferably 6-22cm, and the length is 10-20cm, more preferably 12-16cm.

[0044] According to a preferred embodiment of the present invention, preferably, the diameter of the micropore 8 is 10-100 μm, more preferably 20-50 μm.

[0045] According to a preferred embodiment of the present invention, preferably, the porosity of the crossflow microscale structure 7 is 30-90%, more preferably 60-80%.

[0046] According to a preferred embodiment of the present invention, preferably, the crossflow microscale structure 7 is an annular columnar sheet, more preferably, the thickness of the crossflow microscale structure 7 is 2.5-10 mm, and even more preferably 2.5-8 mm.

[0047] To achieve better gas-liquid mixing efficiency in the reaction process, according to a preferred embodiment of the present invention, such as... Figure 3 As shown, the sleeve is provided with multiple layers of cross-microscale structures 10, and each layer is coaxially fixed with gaps and staggered at a certain angle, so that the homogeneous solution reacts in the state of flowing and mixing between the cross-microscale structures 10.

[0048] According to a preferred embodiment of the present invention, preferably, the diameter of the sleeve 41 is 5-27cm, more preferably 6-22cm, and the length is 20-40cm, more preferably 24-32cm.

[0049] According to a preferred embodiment of the present invention, preferably, the diameter of the concentric shaft 9 is 1-2 cm, and the length of the concentric shaft 9 is the same as the length of the sleeve 41.

[0050] According to a preferred embodiment of the present invention, preferably, the number of layers of the cross microscale structure 10 is 50-100 layers, more preferably 70-90 layers.

[0051] According to a preferred embodiment of the present invention, preferably, the positioning offset angle between two adjacent layers of the intersecting microscale structures 10 is 5-10°, more preferably 6-8°.

[0052] According to a preferred embodiment of the present invention, preferably, the cross-microscale structure 10 is an annular columnar sheet, more preferably, the thickness of the cross-microscale structure 10 is 0.25-1 mm, and even more preferably 0.25-0.8 mm.

[0053] According to a preferred embodiment of the present invention, the slit 11 has an angle with the axis of the intersecting microscale structure 10, and there is an overlapping portion between adjacent slits 11 along their own length direction. The structure of the slit 11 in the present invention can ensure a high degree of gas dispersion in the liquid phase for a long time.

[0054] According to a preferred embodiment of the present invention, preferably, the width of the slit 11 is 5-50 μm, more preferably 10-30 μm.

[0055] According to a preferred embodiment of the present invention, preferably, the length of the slit 11 is 1-5cm, more preferably 2-3cm.

[0056] According to a preferred embodiment of the present invention, preferably, the interval between adjacent slits 11 is 5-50 μm, more preferably 10-30 μm.

[0057] According to a preferred embodiment of the present invention, preferably, the angle between the slit 11 and the axis of the intersecting microscale structure 10 is 10-80°, more preferably 15-45°.

[0058] According to a preferred embodiment of the present invention, the hydraulic diameter of the gaseous feedstock inlet 2 is 1000-3000 μm, preferably 1500-2000 μm.

[0059] According to a preferred embodiment of the present invention, the hydraulic diameter of the liquid phase mixing channel 6 is 200-1000 μm, preferably 300-600 μm, and the length of the liquid phase mixing channel 6 is the same as the length of the housing 31. It should be noted that a filter membrane is provided inside the liquid phase mixing channel 6, 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.

[0060] According to a preferred embodiment of the present invention, the multi-stage continuous reaction channel has 2-10 stages in series, preferably 4-8 stages; each stage includes a mixing module 3 and a reaction module 4 connected in series. According to a preferred embodiment of the present invention, the product outlet 5 is connected to a separation module, which is connected to at least one of the mixing modules 3, for mixing and recycling the protective gas separated from the product with the raw material gas, thereby reducing the amount of inert gas used and making rational use of resources.

[0061] According to a preferred embodiment of the present invention, preferably, the hydraulic diameter of the product outlet 5 is 200-800 μm, more preferably 400-600 μm.

[0062] According to a preferred embodiment of the present invention, the materials of the liquid phase raw material inlet 1, the mixing module 3, the reaction module 4 and the product outlet 5 are selected from one or more of metals, alloys and ceramics, preferably one or more of stainless steel 316L, Hastelloy C and silicon carbide ceramics.

[0063] A second aspect of the present invention also provides the preferred application of the reaction apparatus described herein in a gas-liquid two-phase contact reaction, including:

[0064] 1) The gaseous feedstock and the liquid feedstock are mixed in the primary mixing module to obtain a primary homogeneous solution under the mixing conditions, which is then sent to the primary reaction module;

[0065] 2) Under the reaction conditions, the primary homogeneous solution is reacted in the primary reaction module to obtain the primary discharge, which is then sent to the secondary mixing module;

[0066] 3) The gaseous raw material supplemented through the secondary gaseous raw material inlet is mixed with the primary effluent from step 2) in the secondary mixing module to obtain a secondary homogeneous solution under mixing conditions, and then sent to the secondary reaction module to obtain a secondary effluent under reaction conditions;

[0067] Similarly, the material discharged from the previous stage reaction module enters the next stage mixing module and is mixed with the supplemented gaseous raw material to continue the reaction until the liquid phase raw material conversion rate reaches the target value and is collected by product outlet 5. The liquid phase raw material includes raw materials, catalysts and optional catalyst additives.

[0068] This invention constructs a multi-stage coupled mixing-reaction process, which is particularly suitable for gas-liquid ratio reaction processes. It allows for separate control of temperature, pressure, and gas-liquid ratio conditions in both the mixing and reaction processes, matching the mixing and dissolution rate of the reaction system with the reaction progress of each stage. This effectively limits the heat release of the reaction process while ensuring gas-liquid mixing efficiency under a certain gas-liquid ratio. It has good applicability to heterogeneous reaction systems with a gas-liquid ratio and strong thermal effects, and can be used for continuous processes of various gas-liquid reaction systems. The effect is particularly significant for the acetylene-based synthesis of NVP.

[0069] The method of the present invention is particularly suitable for gas-liquid two-phase contact reactions with a gas-liquid molar ratio of 10 or higher.

[0070] A third aspect of the present invention also provides a method for preparing N-vinylpyrrolidone, which is implemented using the microchannel reaction device described in the present invention. The liquid-phase raw material is fed into the primary mixing module in one step, and each mixing module is equipped with an inlet for the gas-phase raw material, allowing for segmented feeding of the gas-phase raw material. The method includes the following steps:

[0071] 1) The gaseous feedstock and the liquid feedstock are mixed in the primary mixing module to obtain a primary homogeneous solution under the mixing conditions, which is then sent to the primary reaction module;

[0072] 2) Under the reaction conditions, the primary homogeneous solution is reacted in the primary reaction module to obtain the primary discharge, which is then sent to the secondary mixing module;

[0073] 3) The gaseous raw material supplemented through the secondary gaseous raw material inlet is mixed with the primary effluent from step 2) in the secondary mixing module to obtain a secondary homogeneous solution under mixing conditions, and then sent to the secondary reaction module to obtain a secondary effluent under reaction conditions;

[0074] Similarly, the material discharged from the previous stage reaction module enters the next stage mixing module and is mixed with the supplemented gaseous raw material to continue the reaction until the liquid raw material conversion rate reaches the target value and is collected by product outlet 5.

[0075] The gaseous raw material includes a raw material gas and a protective gas. The raw material gas is acetylene, and the protective gas is selected from one or more of nitrogen, argon, helium, carbon dioxide and low-carbon alkanes, preferably selected from carbon dioxide and / or low-carbon alkanes.

[0076] The liquid-phase raw material includes a raw material, a catalyst, and an optional catalyst promoter. The raw material is α-pyrrolidone, the catalyst is potassium pyrrolidone, and the catalyst promoter is polytetrahydrofuran.

[0077] It should be noted that the method described in this invention involves mixing at low temperatures and reacting at high temperatures. During the reaction, a portion of the raw material gas reacts rapidly to generate the target product, while another portion of the raw material gas escapes along with the protective gas due to the temperature increase. This method enables the escaped raw material gas to be redissolved and further transformed, effectively limiting the heat release during the reaction process while ensuring the gas-liquid mixing efficiency at a certain gas-liquid ratio. It has good applicability to heterogeneous reaction systems with a large gas-liquid ratio and strong thermal effect, and can be used for continuous processes of various different gas-liquid reaction systems.

[0078] According to a preferred embodiment of the present invention, the mixing conditions include: a mixing temperature of 50-100°C, a mixing pressure of 1.0-3.0 MPa, and a residence time of 5-10 min in each mixing module.

[0079] According to a preferred embodiment of the present invention, the reaction conditions include: a reaction temperature of 120-180°C, preferably 160-180°C; a reaction pressure of 1.5-3.5 MPa; and a residence time in each of the reaction modules of the present invention of 10-15 min.

[0080] According to a preferred embodiment of the present invention, along the material flow direction, the gas phase feed ratio of each mixing module is L(n):L(n+1) = 1-3:1.

[0081] 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.

[0082] The apparatus and method of the present invention will be further described below with reference to embodiments.

[0083] Example 1

[0084] (1)Reference Figure 1 The apparatus shown is a microchannel reactor with a two-stage mixing-reaction coupling unit for synthesizing NVP. Different modules of the microchannel reactor are temperature-controlled by an independent integrated heating and cooling unit, and crude NVP can be collected from the product outlet.

[0085] The device includes: two continuous reaction channels, each of which is formed by a mixing module 3 and a reaction module 4, and each mixing module 3 is provided with a gaseous raw material inlet 2;

[0086] Each mixing module 3 includes a housing 31 connected to the gaseous raw material inlet 2 and a cross-flow microscale structure 7 with a liquid phase mixing channel 6 disposed in the housing 31. The liquid phase mixing channel 6 is connected to the liquid raw material inlet 1. Multiple micropores 8 are formed on the wall of the cross-flow microscale structure 7, so that the gaseous raw material enters the liquid phase mixing channel 6 through the micropores 8 and dissolves and mixes with the liquid raw material to form a homogeneous solution.

[0087] The reaction module 4 includes a sleeve 41, a concentric shaft 9 disposed inside the sleeve 41, and a cross microscale structure 10 disposed between the sleeve 41 and the concentric shaft 9. The cross microscale structure 10 has multiple slits 11 on its wall. The diameter of the concentric shaft 9 is smaller than that of the liquid phase mixing channel 6, so that the homogeneous solution flows into the multiple slits 11 and reacts in the reaction module 4.

[0088] The main body of the microchannel reactor is made of 316L stainless steel. Micrometer-scale structures are precision-machined onto the stainless steel substrate. In the mixing module 3 and reaction module 4, multi-layered cross-flow microscale structures 7 and intersecting microscale structures 10 are stacked in a concentric ring pattern, respectively. After sealing the relevant interfaces, the fluid channels of the micromixer are formed. The specific arrangement and dimensions are as follows: the hydraulic diameter of the gaseous feed inlet 2 is 2000 μm; the hydraulic diameter of the product outlet 5 is 600 μm; the diameter of the shell 31 is 8 cm and the length is 16 cm; the liquid-phase mixing channel 6 has the same length as the shell and a hydraulic diameter of 500 μm. The thickness of the cross-flow microscale structure 7 is 4 mm, and the number of layers is 8. The diameter of the micropores 8 of the cross-flow microscale structure 7 is 50 μm, the porosity is 80%, and the positioning angle between each layer of the cross-flow microscale structure 7 is 8°. The diameter of the sleeve 41 is 8 cm, the length is 32 cm, and the diameter of the concentric shaft 9 is 1 cm. The thickness of the cross microscale structure 10 is 0.4 mm, and the number of layers is 80. The width of the slits 11 of the cross microscale structure 10 is 30 μm, the spacing of the slits 11 is 20 μm, the length of the slits 11 is 3 cm, the inclination angle of the slits 11 is 30°, and the positioning angle between each layer of the cross microscale structure 10 is 8°.

[0089] (2) NVP Synthesis: A metering pump is used to deliver liquid-phase raw materials, consisting of α-pyrrolidone, potassium pyrrolidone catalyst, and polytetrahydrofuran catalyst promoter (2% by mass of catalyst and 2% by mass of promoter). A mass flow meter is used to deliver gaseous raw materials acetylene and protective gas carbon dioxide at the same flow rate. In each stage of the mixer, the molar flow ratio of acetylene to protective gas carbon dioxide is 1:1, and the gaseous feed rate is the same for each stage of the mixer. The total molar flow ratio of the main raw materials in the metering pump and mass flow meter is set to acetylene:pyrrolidone = 1.5:1. The three materials are fully contacted in the mixing module before entering the reaction module 4 for the vinylation reaction of pyrrolidone. The temperature of each stage of the mixing module 3 is controlled at 20°C and the pressure at 2.0 MPa, and the temperature of each stage of the reaction module 4 is controlled at 180°C and the reaction pressure at 2.0 MPa. The flow rates of the metering pump and mass flow meter are adjusted, and the residence time of the reactants in each stage of the mixing module 3 is controlled at 1 min, and the residence time in each stage of the reaction module 4 is controlled at 5 min. The material at product outlet 5 of the microchannel reactor is crude N-vinylpyrrolidone. Product analysis results show that the conversion rate of 2-pyrrolidone is 65.3%, the selectivity of N-vinylpyrrolidone is 98.1%, and the acetylene conversion rate is 43.2%.

[0090] Example 2

[0091] All steps in this embodiment are basically the same as in Example 1. The difference is that the hydraulic diameter of the liquid phase mixing channel 6 in this embodiment is 1000 μm. The product analysis results show that the conversion rate of 2-pyrrolidone is 55.4%, the selectivity of N-vinylpyrrolidone is 98.3%, and the conversion rate of acetylene is 32.9% during the reaction.

[0092] Example 3

[0093] All steps in this embodiment are basically the same as in Example 1. The difference is that the hydraulic diameter of the liquid phase mixing channel 6 in this embodiment is 300 μm. The product analysis results show that the conversion rate of 2-pyrrolidone is 66.4%, the selectivity of N-vinylpyrrolidone is 97.3%, and the conversion rate of acetylene is 45.1% during the reaction.

[0094] Example 4

[0095] All steps in this embodiment are basically the same as in Example 1. The difference is that the micropore diameter of the cross-flow microscale structure in this embodiment is 100 μm. The product analysis results show that the conversion rate of 2-pyrrolidone is 56.6%, the selectivity of N-vinylpyrrolidone is 98.0%, and the conversion rate of acetylene is 36.4% during the reaction.

[0096] Example 5

[0097] All steps in this embodiment are basically the same as in Example 1. The difference is that the micropore diameter of the cross-flow microscale structure in this embodiment is 30 μm. The product analysis results show that the conversion rate of 2-pyrrolidone is 65.9%, the selectivity of N-vinylpyrrolidone is 96.8%, and the conversion rate of acetylene is 44.9% during the reaction.

[0098] Example 6

[0099] All steps in this embodiment are basically the same as in Example 1. The difference is that the slit width of the cross microscale structure in this embodiment is 80 μm. The product analysis results show that the conversion rate of 2-pyrrolidone is 46.4%, the selectivity of N-vinylpyrrolidone is 98.8%, and the conversion rate of acetylene is 27.3% during the reaction.

[0100] Example 7

[0101] All steps in this embodiment are basically the same as in Example 1. The difference is that the slit width of the cross microscale structure in this embodiment is 10 μm. The product analysis results show that the conversion rate of 2-pyrrolidone is 67.1%, the selectivity of N-vinylpyrrolidone is 96.1%, and the conversion rate of acetylene is 47.1% during the reaction.

[0102] Example 8

[0103] All steps in this embodiment are basically the same as in Example 1. The difference is that in this embodiment, the protective gas for the gaseous raw material is nitrogen. The product analysis results show that the conversion rate of 2-pyrrolidone is 52.1%, the selectivity of N-vinylpyrrolidone is 99.1%, and the conversion rate of acetylene is 35.6% during the reaction.

[0104] Example 9

[0105] All steps in this embodiment are basically the same as in Example 1. The difference is that the protective gas for the gas phase feedstock in this embodiment is propane. The product analysis results show that the conversion rate of 2-pyrrolidone is 68.9%, the selectivity of N-vinylpyrrolidone is 97.8%, and the conversion rate of acetylene is 48.2% during the reaction.

[0106] Example 10

[0107] All steps in this embodiment are basically the same as in Example 1. The difference is that the reaction temperature in this embodiment is 140℃. The product analysis results show that the conversion rate of 2-pyrrolidone is 38.2%, the selectivity of N-vinylpyrrolidone is 99.8%, and the conversion rate of acetylene is 22.2% during the reaction.

[0108] Example 11

[0109] All steps in this embodiment are basically the same as in Example 1. The difference is that the reaction pressure in this embodiment is 1.6 MPa. The product analysis results show that the conversion rate of 2-pyrrolidone is 56.4%, the selectivity of N-vinylpyrrolidone is 98.7%, and the conversion rate of acetylene is 37.9% during the reaction.

[0110] Comparative Example 1

[0111] N-vinylpyrrolidone was synthesized using a batch stirred tank reactor. 500g of α-pyrrolidone, potassium pyrrolidone catalyst, and polytetrahydrofuran catalyst (2% catalyst and 2% catalyst by mass) were placed in a 2L reactor. The reactor was heated to 180℃ and pressurized to 2.0 MPa, with an acetylene:pyrrolidone ratio of 1.5:1. A gaseous feedstock (50% acetylene and 50% nitrogen by volume) was continuously introduced at a rate of 300 ml / min. After 6 hours of reaction, the liquid product was collected. Product analysis showed that the conversion rate of 2-pyrrolidone was 50.1%, the selectivity of N-vinylpyrrolidone was 90.8%, and the conversion rate of acetylene was 18.1%.

[0112] The results above show that the technology provided by this invention has a significant advantage in reaction efficiency compared to the traditional batch reactor process.

[0113] 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. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. 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 multi-stage continuous reaction channel, which is formed by continuously alternating series connection of a mixing module (3) and a reaction module (4). The two ends of the multi-stage continuous reaction channel are respectively connected to a liquid raw material inlet (1) and a product outlet (5). Each mixing module (3) is provided with a gaseous raw material inlet (2) for feeding gaseous raw materials into the mixing modules (3) of each stage in multiple streams. Each mixing module (3) includes a housing (31) connected to the gaseous raw material inlet (2) and a multi-layer cross-flow microscale structure (7) with a liquid phase mixing channel (6) disposed in the housing (31). The layers are coaxially fixed without gaps and staggered at a certain angle. The liquid phase mixing channel (6) is connected to the liquid phase raw material inlet (1). Multiple micropores (8) are opened on the wall of the cross-flow microscale structure (7), so that the micropores (8) of each layer overlap to form a gradually decreasing gaseous raw material channel, so that the gaseous raw material forms tiny bubbles and dissolves and mixes with the liquid raw material to form a homogeneous solution. The reaction module (4) includes a sleeve (41), a concentric shaft (9) disposed inside the sleeve (41), and a cross microscale structure (10) sleeved between the sleeve (41) and the concentric shaft (9). Multiple slits (11) are opened on the wall of the cross microscale structure (10). The diameter of the concentric shaft (9) is smaller than that of the liquid phase mixing channel (6), so that the homogeneous solution flows into the multiple slits (11) and reacts in the reaction module (4).

2. The reaction apparatus according to claim 1, wherein, The crossflow microscale structure (7) has 5-10 layers.

3. The reaction apparatus according to claim 2, wherein, The crossflow microscale structure (7) has 7-9 layers.

4. The reaction apparatus according to claim 1, wherein, The staggered angle between the two adjacent layers of the crossflow microscale structure (7) is 5-10°.

5. The reaction apparatus according to claim 4, wherein, The staggered angle between the two adjacent layers of the crossflow microscale structure (7) is 6-8°.

6. The reaction apparatus according to claim 1, wherein, The diameter of the shell (31) is 5-27cm and the length is 10-20cm.

7. The reaction apparatus according to claim 6, wherein, The diameter of the shell (31) is 6-22cm and the length is 12-16cm.

8. The reaction apparatus according to claim 1, wherein, The diameter of the micropore (8) is 10-100 μm.

9. The reaction apparatus according to claim 8, wherein, The diameter of the micropore (8) is 20-50 μm.

10. The reaction apparatus according to claim 1, wherein, The porosity of the crossflow microscale structure (7) is 30-90%.

11. The reaction apparatus according to claim 10, wherein, The porosity of the crossflow microscale structure (7) is 60-80%.

12. The reaction apparatus according to claim 1, wherein, The crossflow microscale structure (7) is a ring-shaped columnar sheet.

13. The reaction apparatus according to claim 12, wherein, The thickness of the crossflow microscale structure (7) is 2.5-10 mm.

14. The reaction apparatus according to claim 13, wherein, The thickness of the crossflow microscale structure (7) is 2.5-8 mm.

15. The reaction apparatus according to claim 1, wherein, The sleeve (41) is provided with a multi-layered cross-microscale structure (10), with each layer coaxially fixed with gaps and staggered at a certain angle, so that the homogeneous solution reacts in the state of flowing and mixing between the cross-microscale structures (10) of each layer.

16. The reaction apparatus according to claim 15, wherein, The sleeve (41) has a diameter of 5-27cm and a length of 20-40cm.

17. The reaction apparatus according to claim 16, wherein, The sleeve (41) has a diameter of 6-22cm and a length of 24-32cm.

18. The reaction apparatus according to claim 15, wherein, The diameter of the concentric shaft (9) is 1-2 cm, and the length of the concentric shaft (9) is the same as the length of the sleeve (41).

19. The reaction apparatus according to claim 15, wherein, The number of layers in the cross-microscale structure (10) is 50-100.

20. The reaction apparatus according to claim 19, wherein, The number of layers in the cross-microscale structure (10) is 70-90.

21. The reaction apparatus according to claim 15, wherein, The positioning angle between the two adjacent layers of the cross microscale structure (10) is 5-10°.

22. The reaction apparatus according to claim 21, wherein, The positioning angle between the two adjacent layers of the cross microscale structure (10) is 6-8°.

23. The reaction apparatus according to claim 15, wherein, The cross-microscale structure (10) is a ring-shaped columnar sheet.

24. The reaction apparatus according to claim 23, wherein, The thickness of the cross microscale structure (10) is 0.25-1 mm.

25. The reaction apparatus according to claim 24, wherein, The thickness of the cross-microscale structure (10) is 0.25-0.8 mm.

26. The reaction apparatus according to claim 1, wherein, The slit (11) has an angle with the axis of the intersecting microscale structure (10), and there is an overlap between adjacent slits (11) along their own length direction.

27. The reaction apparatus according to claim 1, wherein, The width of the slit (11) is 5-50 μm.

28. The reaction apparatus according to claim 27, wherein, The width of the slit (11) is 10-30 μm.

29. The reaction apparatus according to claim 26, wherein, The slit (11) is 1-5 cm long.

30. The reaction apparatus according to claim 29, wherein, The slit (11) is 2-3 cm long.

31. The reaction apparatus according to claim 26, wherein, The interval between adjacent slits (11) is 5-50 μm.

32. The reaction apparatus according to claim 31, wherein, The interval between adjacent slits (11) is 10-30 μm.

33. The reaction apparatus according to claim 26, wherein, The angle between the slit (11) and the axis of the intersecting microscale structure (10) is 10-80°.

34. The reaction apparatus according to claim 33, wherein, The angle between the slit (11) and the axis of the intersecting microscale structure (10) is 15-45°.

35. The reaction apparatus according to claim 1, wherein, The hydraulic diameter of the gaseous feedstock inlet (2) is 1000-3000 μm; and / or The hydraulic diameter of the liquid phase mixing channel (6) is 200-1000 μm, and the length of the liquid phase mixing channel (6) is the same as the length of the shell (31); and / or The hydraulic diameter of the product outlet (5) is 200-800 μm.

36. The reaction apparatus according to claim 35, wherein, The hydraulic diameter of the gaseous feedstock inlet (2) is 1500-2000 μm; and / or The hydraulic diameter of the liquid phase mixing channel (6) is 300-600 μm; and / or The hydraulic diameter of the product outlet (5) is 400-600 μm.

37. The reaction apparatus according to claim 1, wherein, The number of series stages of the multi-stage continuous reaction channel is 2-10; each stage includes a series-connected mixing module (3) and a reaction module (4).

38. The reaction apparatus according to claim 37, wherein, The number of cascaded stages in the multi-stage continuous reaction channel is 2-8.

39. The reaction apparatus according to claim 1, wherein, The materials of the liquid raw material inlet (1), mixing module (3), reaction module (4) and product outlet (5) are selected from one or two of metals and ceramics.

40. The reaction apparatus according to claim 39, wherein, The materials of the liquid phase raw material inlet (1), mixing module (3), reaction module (4) and product outlet (5) are selected from one or more of stainless steel 316L, Hastelloy C and silicon carbide ceramics.

41. The application of the reaction apparatus according to any one of claims 1-40 in a gas-liquid two-phase contact reaction, comprising: 1) The gaseous feedstock and the liquid feedstock are mixed in the primary mixing module to obtain a primary homogeneous solution under the mixing conditions, which is then sent to the primary reaction module; 2) Under the reaction conditions, the primary homogeneous solution is reacted in the primary reaction module to obtain the primary discharge, which is then sent to the secondary mixing module; 3) The gaseous raw material supplemented through the secondary gaseous raw material inlet is mixed with the primary effluent from step 2) in the secondary mixing module to obtain a secondary homogeneous solution under mixing conditions, and then sent to the secondary reaction module to obtain a secondary effluent under reaction conditions; Similarly, the material discharged from the previous stage reaction module enters the next stage mixing module and is mixed with the supplemented gaseous raw material to continue the reaction until the liquid raw material conversion rate reaches the target value and is collected by the product outlet (5). The liquid raw material includes raw material, catalyst and optional catalyst additive.

42. A method for preparing N-vinylpyrrolidone, characterized in that, This method is implemented using the microchannel reaction device according to any one of claims 1-40. The liquid-phase raw material is fed into the primary mixing module in one go, and each mixing module is provided with an inlet for the gas-phase raw material to allow for segmented feeding of the gas-phase raw material. The method includes the following steps: 1) The gaseous feedstock and the liquid feedstock are mixed in the primary mixing module to obtain a primary homogeneous solution under the mixing conditions, which is then sent to the primary reaction module; 2) Under the reaction conditions, the primary homogeneous solution is reacted in the primary reaction module to obtain the primary discharge, which is then sent to the secondary mixing module; 3) The gaseous raw material supplemented through the secondary gaseous raw material inlet is mixed with the primary effluent from step 2) in the secondary mixing module to obtain a secondary homogeneous solution under mixing conditions, and then sent to the secondary reaction module to obtain a secondary effluent under reaction conditions; In this way, the material discharged from the previous stage reaction module enters the next stage mixing module and is mixed with the supplemented gaseous raw material to continue the reaction until the liquid raw material conversion rate reaches the target value and is collected by the product outlet (5). The gaseous raw material includes a raw material gas and a protective gas. The raw material gas is acetylene, and the protective gas is selected from one or more of nitrogen, argon, helium, carbon dioxide, and low-carbon alkanes. The liquid-phase raw material includes a raw material, a catalyst, and an optional catalyst promoter. The raw material is α-pyrrolidone, the catalyst is potassium pyrrolidone, and the catalyst promoter is polytetrahydrofuran.

43. The method according to claim 42, wherein, The feed gas is selected from carbon dioxide and / or low-carbon alkanes.

44. The method according to claim 42, wherein, The mixing conditions include: a mixing temperature of 20-100℃, a mixing pressure of 1.0-3.0MPa, and a residence time of 1-10min in each mixing module (3); and / or The reaction conditions include: a reaction temperature of 120-180℃; a reaction pressure of 1.5-3.5MPa; and a residence time of 5-15 min in each of the reaction modules (4); and / or Along the material flow direction, the gas phase feed ratio of each mixing module is L(n):L(n+1) = 1-3:

1.

45. The method according to claim 44, wherein, The reaction temperature is 160-180℃.

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