Micro-channel reaction device and application thereof

Abstract

The invention discloses a micro-channel reaction device and application thereof. The device comprises a mixing area and a reaction area, the mixing area comprises an inlet channel, a mixing channel and an outlet channel which are sequentially communicated, the mixing channel comprises a plurality of first mixing channels and a plurality of second mixing channels, and the first mixing channels and the second mixing channels are alternately and circularly arranged; each first mixing channel and each second mixing channel are respectively provided with a micro-scale streaming structure, and the reaction area is a straight-through channel. The structural configuration is suitable for liquid phase reactions under various high-temperature and high-pressure conditions, uniform mixing of various raw materials can be achieved within a short retention time, the raw materials are further efficiently converted in the subsequent delayed reaction, the reasonable channel volumes of the mixing area and the reaction area are matched according to the reaction kinetic characteristics of different reactions, and the reaction efficiency is improved. The mass transfer efficiency and the heat transfer efficiency in the reaction process can be effectively optimized, and the efficient mixing efficiency and safety in the chemical process flow are guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of micro-chemical industry and fine chemical industry, and in particular to a micro-channel reaction device and application thereof. Background Art

[0002] Microchemical technology began in the early 1990s. This technology uses micron-scale channel reactors for reactions and is an emerging technology that can enhance mixing, separation, heat exchange, control and other processes. A microchannel reactor is a reaction device with a microstructure manufactured by micromachining technology. The internal submillimeter-level three-dimensional microscale structure can quickly mix multiple fluids and disperse them into a mixed fluid with a size between 1μm and 1mm. Compared with traditional kettle reactions, it has the following advantages: (1) The reaction process is continuous and the synthesis efficiency is improved; (2) The structure is controllable due to regular flow; (3) The specific surface area is increased due to microchannels, which enables rapid heat exchange; (4) The mass transfer mixing process is enhanced to avoid side reactions caused by reflux; (5) There are fewer raw materials remaining in the reactor, and the reaction process is safe and controllable; (6) Large-scale amplification can reduce the amplification effect.

[0003] At present, major universities and companies at home and abroad have started the research of micro-chemical technology, such as the modular micro-reactor of Ehrfeld, a subsidiary of Bayer in Germany, the SIMM micro-reactor of IMM in Germany, the Siprocess micro-reaction system of Siemens, and the G1-G4 micro-channel technology of Corning in the United States. In addition, DuPont, BASF, Syrris, Shenshi, Weijing Technology, and Haomai in China have also developed their own micro-reaction systems and applied them to various reactions.

[0004] Patent application CN103894126A discloses a microchannel reactor and the application of preparing 1,2-hexanediol in the microchannel reactor, which significantly improves production efficiency and product purity. Patent application CN113620825A discloses a microchannel reactor and a method for preparing dimethylaminoethyl acetate using the microchannel reactor, which is continuously produced and avoids the problem of gas leakage. Patent application CN109293525A discloses a microchannel reactor and a method for preparing N-alkoxy oxalyl alanine ester using the microchannel reactor, which utilizes the microstructure inside the microchannel reactor, excellent mass transfer and heat transfer capabilities, and has the advantages of high yield and low energy consumption. However, the mixing efficiency of these microchannel reaction devices is not high. For reversible reactions such as esterification reactions, this will lead to unfavorable factors such as droplet breakage and back mixing, making the conversion rate and selectivity of the reaction process low. Therefore, it is very necessary to develop a microreactor under high pressure conditions according to the physicochemical properties of the substrate. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the existing microchannel reactor that it is not suitable for liquid phase reaction under high pressure conditions and has low conversion rate and selectivity when used for esterification reaction, and to provide a microchannel reaction device and its application.

[0006] In order to achieve the above-mentioned objectives, the present invention provides a microchannel reaction device on the one hand, comprising a mixing zone and a reaction zone, wherein the mixing zone comprises an inlet channel, a mixing channel and an outlet channel connected in sequence, wherein the mixing channel comprises a plurality of first mixing channels and a plurality of second mixing channels, and the first mixing channels and the second mixing channels are arranged alternately and cyclically, each of the first mixing channels and each of the second mixing channels has a microscale flow structure, and the reaction zone is a straight-through channel.

[0007] Preferably, the inlet channel of the mixing zone has at least two channels arranged parallel to each other, and the reaction material enters the mixing channel vertically through the inlet channel.

[0008] Preferably, the inlet channel of the mixing zone has three channels arranged in parallel with each other, and the hydraulic diameter of the inlet channel is 200-2000 μm and the length is 1-2 mm.

[0009] Preferably, the first mixing channel has two layers of flow channels arranged symmetrically along the central axis, each layer of flow channels is divided into seven modules, module a1 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 1371-2056 μm, the channel height is 0.5-2 mm, the hydraulic diameter at the outlet is 920-1380 μm, the channel height is 0.5-2 mm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3 mm, and the plane where the inlet channel is located is taken as the reference plane, the slope of module a1 is 30-60°; the outlet of module a1 is connected to module a Module a2, the module a2 is a straight channel and is perpendicular to the reference plane, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; modules a3, a4 and a5 are reflux areas, the fluid flow direction at the connection between the module a3 and the module a2 is perpendicular to the fluid flow direction in the module a2; the module a4 is a mixed reflux area, the fluids of the upper and lower layers of the flow channel are collected and mixed in the module a4 and then redistributed into two A stream of fluid flows out, and the flow direction of the outflowing fluid is opposite to the flow direction of the fluid in the a2 module, the inlet cross-section width is 0.5-2mm, the height is 1-4mm, the outlet cross-section width is 0.5-2mm, and the height is 0.5-2mm; the a5 module is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the a6 module; the a6 module is symmetrical with the a2 module along the central axis Arranged and kept parallel to each other, and the fluid flow direction in the a6 module is consistent with the fluid flow direction in the a2 module, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the a7 module is a channel with variable diameters at the front and back, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross-section and the outlet cross-section is 1-3mm, and the fluid flowing out of the outlet enters the second mixing channel for further mixing.

[0010] Preferably, the second mixing channel has two layers of flow channels arranged symmetrically along the central axis, each layer of flow channels is divided into seven modules, module b1 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 1371-2056 μm, the channel height is 0.5-2 mm, the hydraulic diameter at the outlet is 920-1380 μm, the channel height is 0.5-2 mm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3 mm, and the plane where the inlet channel is located is taken as the reference plane. The slope of module b1 is 120-150°; the outlet of module b1 is connected to module b2, The b2 module is a straight channel and is perpendicular to the reference plane. The channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the b3 module, the b4 module and the b5 module are reflux areas. The fluid flow direction at the connection between the b3 module and the b2 module is perpendicular to the fluid flow direction in the b2 module; the b4 module is a mixed reflux area. The fluids in the upper and lower layers of the flow channel are collected and mixed in the b4 module and then redistributed into two fluid flows, and the outflowing fluid The flow direction is opposite to that of the fluid in the b2 module, the inlet cross-section width is 0.5-2mm, the height is 1-4mm, the outlet cross-section width is 0.5-2mm, and the height is 0.5-2mm; the b5 module is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the b6 module; the b6 module and the b2 module are arranged symmetrically along the central axis and remain parallel to each other, and the b6 module The fluid flow direction inside is consistent with that in the module b2, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; module b7 is a channel with variable diameters at the front and back, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross-section and the outlet cross-section is 1-3mm, and the fluid flowing out of the outlet enters the subsequent first mixing channel for continued mixing or enters the reaction zone through the outlet channel for delayed reaction.

[0011] Preferably, the outlet channel of the mixing zone has a hydraulic diameter of 200-2000 μm and a length of 1-2 mm.

[0012] Preferably, the hydraulic diameter of the straight channel of the reaction zone is 200-2000 μm, preferably 800-1500 μm; the length of the straight channel of the reaction zone is 20-100 cm, preferably 50-100 cm; the straight channel of the reaction zone has the same diameter as the outlet channel of the mixing zone.

[0013] Preferably, the material of each fluid channel of the microchannel reaction device is independently selected from stainless steel 316L, 904 stainless steel, Hastelloy and silicon carbide ceramics.

[0014] The second aspect of the present invention provides a method for liquid phase esterification reaction, which is implemented in the above-mentioned microchannel reaction device, and the method comprises: injecting the reaction raw materials and the catalyst into the mixing zone through the inlet channel respectively for mixing, and entering the reaction zone for reaction.

[0015] Preferably, the method is used to synthesize methyl thioglycolate.

[0016] Preferably, the reaction conditions include: temperature of 50-100° C., pressure of 0-0.3 MPa (gauge pressure), and residence time of 30-90 min.

[0017] The microchannel reaction device described in the present invention includes two main areas, a mixing zone and a reaction zone, wherein the mixing zone has a precisely machined complex microscale flow structure for achieving uniform mixing of raw materials; the reaction zone is a straight-through channel for delayed reaction. This structural configuration is suitable for liquid phase reactions under various high temperature and high pressure conditions, can achieve uniform mixing of various raw materials in a short residence time, and further efficiently convert the raw materials in subsequent delayed reactions. The channel volumes of the mixing zone and the reaction zone are matched reasonably according to the reaction kinetic characteristics of different reactions, which can effectively optimize the mass transfer and heat transfer efficiency during the reaction process, and ensure efficient mixing efficiency and safety in the chemical process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of a mixing zone in a microchannel reaction device according to the present invention;

[0019] Figure 2 It is a schematic structural diagram of a portion of the fluid channels in the mixing zone of the microchannel reaction device of the present invention;

[0020] Figure 3 It is a top view of the structure of a layer of flow channels in the first mixing channel of the mixing zone in the microchannel reaction device of the present invention;

[0021] Figure 4 It is a top view of the structure of a layer of flow channels in the second mixing channel of the mixing zone in the microchannel reaction device described in the present invention.

[0022] Description of Reference Numerals

[0023] a, first mixing channel; b, second mixing channel;

[0024] 1. Module a1; 2. Module a2; 3. Module a3; 4. Module a4; 5. Module a5; 6. Module a6; 7. Module a7;

[0025] 8. Module b1; 9. Module b2; 10. Module b3; 11. Module b4; 12. Module b5; 13. Module b6; 14. Module b7. DETAILED DESCRIPTION

[0026] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0027] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0028] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, unless otherwise specified, features defined as "first" and "second" may explicitly or implicitly include one or more of the features; "several" means two or more. The term "including" and any variation thereof means non-exclusive inclusion, and one or more other features, integers, steps, operations, units, components and / or combinations thereof may exist or be added.

[0029] like Figure 1 and 2 As shown, the microchannel reaction device of the present invention includes a mixing zone and a reaction zone, wherein the mixing zone includes an inlet channel, a mixing channel and an outlet channel connected in sequence, wherein the mixing channel includes a plurality of first mixing channels a and a plurality of second mixing channels b, and the first mixing channels a and the second mixing channels b are arranged alternately and cyclically, each of the first mixing channels a and each of the second mixing channels b has a microscale flow structure, and the reaction zone is a straight-through channel. The mixing zone is used to achieve uniform mixing of multiple raw materials, and the reaction zone is used to perform a delayed reaction on the materials mixed in the mixing zone.

[0030] In the microchannel reaction device of the present invention, the inlet channel of the mixing zone has at least two channels arranged in parallel with each other, and the reaction materials (including reaction raw materials, catalysts and solvents, etc.) enter the mixing channel vertically through the inlet channel. In a more preferred embodiment, the inlet channel of the mixing zone has three channels arranged in parallel with each other, and the hydraulic diameter of the inlet channel is 200-2000 μm and the length is 1-2 mm.

[0031] In the microchannel reaction device of the present invention, preferably, Figure 3As shown, the first mixing channel a has two layers of flow channels arranged symmetrically along the central axis, and each layer of flow channels is divided into seven modules, specifically, module a1 1, module a2 2, module a3 3, module a4 4, module a5 5, module a6 6 and module a7 7 connected in sequence. Specifically, module a1 1 is a channel with front and rear diameter changes, with a hydraulic diameter of 1371-2056 μm at the inlet, a channel height of 0.5-2 mm, a hydraulic diameter of 920-1380 μm at the outlet, a channel height of 0.5-2 mm, a straight-line distance between the inlet section and the outlet section of 1-3 mm, and a slope of 30-60° with the plane where the inlet channel is located as the reference plane; the outlet of module a1 1 is connected to module a2 2, and module a2 2 is a straight channel and perpendicular to the reference plane, with a channel width of 0. 5-1.5mm, 0.5-2mm high, 1-5mm long, and a hydraulic diameter of 920-1380μm; a3 module 3, a4 module 4, and a5 module 5 are reflux areas, and the fluid flow direction at the connection between the a3 module 3 and the a2 module 2 is perpendicular to the fluid flow direction in the a2 module 2; the a4 module 4 is a mixed reflux area, and the fluids in the upper and lower layers of the flow channel are collected and mixed in the a4 module 4 and then redistributed into two fluid flows, and the outflowing fluid flows in the same direction as the a The fluid in module 2 flows in the opposite direction, the inlet cross-section width is 0.5-2mm, the height is 1-4mm, the outlet cross-section width is 0.5-2mm, and the height is 0.5-2mm; module a5 is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to module a6; the module a6 and the module a2 are arranged symmetrically along the central axis and keep each other The a6 module 6 is parallel, and the fluid flow direction in the a6 module 6 is consistent with the fluid flow direction in the a2 module 2. The channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the a7 module 7 is a channel with variable diameters at the front and back, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross-section and the outlet cross-section is 1-3mm, and the fluid flowing out of the outlet enters the second mixing channel b to continue mixing.

[0032] In the microchannel reaction device of the present invention, preferably, Figure 4As shown, the second mixing channel b has two layers of flow channels arranged symmetrically along the central axis, and each layer of flow channels is divided into seven modules, specifically, module b1 8, module b2 9, module b3 10, module b4 11, module b5 12, module b6 13 and module b7 14 connected in sequence. Specifically, module b1 8 is a channel with front and rear diameter changes, with a hydraulic diameter of 1371-2056 μm at the inlet, a channel height of 0.5-2 mm, a hydraulic diameter of 920-1380 μm at the outlet, a channel height of 0.5-2 mm, a straight-line distance between the inlet section and the outlet section of 1-3 mm, and a slope of module b1 8 of 120-150° with the plane where the inlet channel is located as the reference plane; the outlet of module b1 8 is connected to module b2 9, and module b2 9 is a straight channel and perpendicular to the reference plane, with a channel width of 0.5-1.5 mm. The height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the b3 module 10, the b4 module 11 and the b5 module 12 are the reflux areas, and the fluid flow direction at the connection between the b3 module 10 and the b2 module 9 is perpendicular to the fluid flow direction in the b2 module 9; the b4 module 11 is the mixed reflux area, and the fluids in the upper and lower layers of the flow channel are collected and mixed in the b4 module 11 and then redistributed into two fluid flows, and the outflowing fluid flow direction is opposite to the fluid flow direction in the b2 module 9. On the contrary, the inlet cross-sectional width is 0.5-2mm, the height is 1-4mm, the outlet cross-sectional width is 0.5-2mmmm, and the height is 0.5-2mm; the b5 module 12 is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the b6 module; the b6 module 13 and the b2 module 9 are arranged symmetrically along the central axis and remain parallel to each other, and the fluid in the b6 module 13 flows in the same direction as the b2 module 9. The fluid in the b2 module 9 flows in the same direction, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the b7 module 14 is a channel with variable diameters at the front and back, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet section and the outlet section is 1-3mm, and the fluid flowing out of the outlet enters the subsequent first mixing channel (a) to continue mixing or enters the reaction zone through the outlet channel for delayed reaction.

[0033] In the microchannel reaction device of the present invention, the hydraulic diameter of the outlet channel of the mixing zone may be 200-2000 μm, and the length may be 1-2 mm.

[0034] In the microchannel reaction device described in the present invention, the hydraulic diameter of the straight channel of the reaction zone is 200-2000μm, preferably 800-1500μm; the length of the straight channel of the reaction zone is 20-100cm, preferably 50-100cm; the straight channel of the reaction zone has the same diameter as the outlet channel of the mixing zone.

[0035] In the microchannel reaction device of the present invention, the material of each fluid channel of the microchannel reaction device is independently selected from stainless steel 316L, 904 stainless steel, Hastelloy and silicon carbide ceramics.

[0036] In some embodiments, the microchannel reaction device includes a mixing zone and a reaction zone, the mixing zone includes an inlet channel, a mixing channel and an outlet channel connected in sequence, wherein the inlet channel of the mixing zone has at least two channels arranged in parallel to each other, and the reaction material enters the mixing channel vertically through the inlet channel; the mixing channel includes a plurality of first mixing channels a and a plurality of second mixing channels b, and the first mixing channels a and the second mixing channels b are arranged alternately and cyclically, and each of the first mixing channels a and each of the second mixing channels b has a microscale flow structure; the hydraulic diameter of the outlet channel of the mixing zone can be 200-2000μm, and the length can be 1-2mm; the reaction zone is a straight channel, the hydraulic diameter of the straight channel is 200-2000μm, and the length is 20-100cm, and the straight channel has the same diameter as the outlet channel of the mixing zone.

[0037] In other embodiments, the microchannel reaction device includes a mixing zone and a reaction zone, the mixing zone includes an inlet channel, a mixing channel and an outlet channel connected in sequence, wherein the inlet channel of the mixing zone has three channels arranged in parallel to each other, and the hydraulic diameter of the inlet channel is 200-2000μm, and the length is 1-2mm; the mixing channel includes a plurality of first mixing channels a and a plurality of second mixing channels b, and the first mixing channels a and the second mixing channels b are arranged alternately and cyclically, and each of the first mixing channels a and each of the second mixing channels b has a microscale flow structure; the hydraulic diameter of the outlet channel of the mixing zone can be 200-2000μm, and the length can be 1-2mm; the reaction zone is a straight channel, the hydraulic diameter of the straight channel is 800-1500μm, and the length is 50-100cm, and the diameter of the straight channel is consistent with that of the outlet channel of the mixing zone.

[0038] In other embodiments, the microchannel reaction device includes a mixing zone and a reaction zone, the mixing zone includes an inlet channel, a mixing channel and an outlet channel connected in sequence, wherein the inlet channel of the mixing zone has at least two channels arranged in parallel with each other, and the reaction material enters the mixing channel vertically through the inlet channel; the mixing channel includes a plurality of first mixing channels a and a plurality of second mixing channels b, and the first mixing channels a and the second mixing channels b are arranged alternately and cyclically, and each of the first mixing channels a and each of the second mixing channels b has a microscale flow structure, wherein,

[0039] The first mixing channel a has two layers of flow channels arranged symmetrically along the central axis, each layer of flow channels is divided into seven modules, module a1 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 1371-2056 μm, the channel height is 0.5-2 mm, the hydraulic diameter at the outlet is 920-1380 μm, the channel height is 0.5-2 mm, the straight-line distance between the inlet section and the outlet section is 1-3 mm, and the plane where the inlet channel is located is taken as the reference plane, the slope of module a1 is 30-60°; the outlet of module a1 is connected to module a2 , the a2 module 2 is a straight channel and is perpendicular to the reference plane, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the a3 module 3, the a4 module 4 and the a5 module 5 are reflux areas, and the fluid flow direction at the connection between the a3 module 3 and the a2 module 2 is perpendicular to the fluid flow direction in the a2 module 2; the a4 module 4 is a mixed reflux area, and the fluids of the upper and lower layers of the flow channel are collected and mixed in the a4 module 4 and then redistributed into two A stream of fluid flows out, and the flow direction of the outflowing fluid is opposite to the flow direction of the fluid in the a2 module 2, the inlet cross-sectional width is 0.5-2mm, the height is 1-4mm, the outlet cross-sectional width is 0.5-2mm, and the height is 0.5-2mm; the a5 module 5 is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the a6 module 6; the a6 module 6 and the a2 module 2 are mutually opposite along the central axis The a6 module 6 is arranged and kept parallel to each other, and the flow direction of the fluid in the a2 module 2 is consistent with the flow direction of the fluid in the a2 module 2, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the a7 module 7 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3mm, and the fluid flowing out of the outlet enters the second mixing channel b for further mixing;

[0040] The second mixing channel b has two layers of flow channels arranged symmetrically along the central axis, each layer of the flow channel is divided into seven modules, module b1 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 1371-2056μm, the channel height is 0.5-2mm, the hydraulic diameter at the outlet is 920-1380μm, the channel height is 0.5-2mm, the straight-line distance between the inlet section and the outlet section is 1-3mm, and the plane where the inlet channel is located is taken as the reference plane. The slope of module b1 is 120-150°; the outlet of module b1 is connected to module b2, and the b Module No. 2 is a straight channel and is perpendicular to the reference plane. The channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; Modules B3, B4 and B5 are reflux areas. The fluid flow direction at the connection between Module B3 and Module B2 is perpendicular to the fluid flow direction in Module B2; Module B4 is a mixed reflux area. The fluids in the upper and lower layers of the flow channel are collected and mixed in Module B4 and then redistributed into two streams of fluid flowing out. The outflowing fluid flows in the same direction as the flow direction of the fluid flowing out. The fluid in the b2 module flows in the opposite direction, the inlet cross-section is 0.5-2mm wide and 1-4mm high, the outlet cross-section is 0.5-2mm wide and 0.5-2mm high; the b5 module is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the b6 module; the b6 module and the b2 module are arranged symmetrically along the central axis and remain parallel to each other, and the fluid in the b6 module is symmetrical to each other along the central axis and remains parallel to each other, and the fluid in the b6 module is symmetrical to each other along the central axis and remains parallel to each other. The flow direction of the body is consistent with the flow direction of the fluid in the b2 module, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the b7 module is a channel with a front and rear diameter change, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3mm, and the fluid flowing out of the outlet enters the subsequent first mixing channel (a) for continued mixing or enters the reaction zone through the outlet channel for delayed reaction;

[0041] The hydraulic diameter of the outlet channel of the mixing zone can be 200-2000 μm, and the length can be 1-2 mm; the reaction zone is a straight channel, the hydraulic diameter of the straight channel is 200-2000 μm, and the length is 20-100 cm, and the straight channel has the same diameter as the outlet channel of the mixing zone.

[0042] In other embodiments, the microchannel reaction device includes a mixing zone and a reaction zone, the mixing zone includes an inlet channel, a mixing channel and an outlet channel connected in sequence, wherein the inlet channel of the mixing zone has three channels arranged in parallel with each other, and the hydraulic diameter of the inlet channel is 200-2000 μm and the length is 1-2 mm; the mixing channel includes a plurality of first mixing channels a and a plurality of second mixing channels b, and the first mixing channels a and the second mixing channels b are arranged alternately and cyclically, and each of the first mixing channels a and each of the second mixing channels b has a microscale flow structure, wherein,

[0043] The first mixing channel a has two layers of flow channels arranged symmetrically along the central axis, each layer of flow channels is divided into seven modules, module a1 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 1371-2056 μm, the channel height is 0.5-2 mm, the hydraulic diameter at the outlet is 920-1380 μm, the channel height is 0.5-2 mm, the straight-line distance between the inlet section and the outlet section is 1-3 mm, and the plane where the inlet channel is located is taken as the reference plane, the slope of module a1 is 30-60°; the outlet of module a1 is connected to module a2 , the a2 module 2 is a straight channel and is perpendicular to the reference plane, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the a3 module 3, the a4 module 4 and the a5 module 5 are reflux areas, and the fluid flow direction at the connection between the a3 module 3 and the a2 module 2 is perpendicular to the fluid flow direction in the a2 module 2; the a4 module 4 is a mixed reflux area, and the fluids of the upper and lower layers of the flow channel are collected and mixed in the a4 module 4 and then redistributed into two A stream of fluid flows out, and the flow direction of the outflowing fluid is opposite to the flow direction of the fluid in the a2 module 2, the inlet cross-sectional width is 0.5-2mm, the height is 1-4mm, the outlet cross-sectional width is 0.5-2mm, and the height is 0.5-2mm; the a5 module 5 is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the a6 module 6; the a6 module 6 and the a2 module 2 are mutually opposite along the central axis The a6 module 6 is arranged and kept parallel to each other, and the flow direction of the fluid in the a2 module 2 is consistent with the flow direction of the fluid in the a2 module 2, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the a7 module 7 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3mm, and the fluid flowing out of the outlet enters the second mixing channel b for further mixing;

[0044] The second mixing channel b has two layers of flow channels arranged symmetrically along the central axis, each layer of the flow channel is divided into seven modules, module b1 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 1371-2056μm, the channel height is 0.5-2mm, the hydraulic diameter at the outlet is 920-1380μm, the channel height is 0.5-2mm, the straight-line distance between the inlet section and the outlet section is 1-3mm, and the plane where the inlet channel is located is taken as the reference plane. The slope of module b1 is 120-150°; the outlet of module b1 is connected to module b2, and the b Module No. 2 is a straight channel and is perpendicular to the reference plane. The channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; Modules B3, B4 and B5 are reflux areas. The fluid flow direction at the connection between Module B3 and Module B2 is perpendicular to the fluid flow direction in Module B2; Module B4 is a mixed reflux area. The fluids in the upper and lower layers of the flow channel are collected and mixed in Module B4 and then redistributed into two streams of fluid flowing out. The outflowing fluid flows in the same direction as the flow direction of the fluid flowing out. The fluid in the b2 module flows in the opposite direction, the inlet cross-section is 0.5-2mm wide and 1-4mm high, the outlet cross-section is 0.5-2mm wide and 0.5-2mm high; the b5 module is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the b6 module; the b6 module and the b2 module are arranged symmetrically along the central axis and remain parallel to each other, and the fluid in the b6 module is symmetrical to each other along the central axis and remains parallel to each other, and the fluid in the b6 module is symmetrical to each other along the central axis and remains parallel to each other. The flow direction of the body is consistent with the flow direction of the fluid in the b2 module, the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the b7 module is a channel with a front and rear diameter change, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3mm, and the fluid flowing out of the outlet enters the subsequent first mixing channel (a) for continued mixing or enters the reaction zone through the outlet channel for delayed reaction;

[0045] The hydraulic diameter of the outlet channel of the mixing zone can be 200-2000 μm, and the length can be 1-2 mm; the reaction zone is a straight channel, the hydraulic diameter of the straight channel is 800-1500 μm, and the length is 50-100 cm, and the straight channel has the same diameter as the outlet channel of the mixing zone.

[0046] The present invention also provides a method for liquid phase esterification reaction, which is implemented in the microchannel reaction device described above, and comprises: injecting the reaction raw materials and the catalyst into the mixing zone through the inlet channel for mixing, and then entering the reaction zone for reaction.

[0047] In some embodiments, the liquid phase esterification reaction method of the present invention is used to synthesize methyl thioglycolate, wherein the inlet channel of the mixing zone in the microchannel reaction device has three parallel channels, namely, upper, middle and lower channels, the first reaction raw material (such as methanol) enters the mixing zone through the upper channel and the lower channel, and the second reaction raw material (such as thioglycolic acid) dissolves the catalyst and enters the mixing zone through the middle channel, wherein the catalyst concentration can be 0.5-10% by weight. The catalyst can be selected from, for example, p-toluenesulfonic acid, concentrated sulfuric acid, methanesulfonic acid, titanium trichloride and SO4 2- / TiO2 super acid.

[0048] In a preferred embodiment, when methyl thioglycolate is synthesized using the microchannel reaction device of the present invention, the reaction conditions include: temperature of 50-100° C., pressure of 0-0.3 MPa (gauge pressure), and residence time of 30-90 min.

[0049] The microchannel reaction device and its application described in the present invention are further described below by way of examples. The examples are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0050] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0051] Example 1

[0052] The microchannel reaction device used in this embodiment includes a mixing zone and a reaction zone, wherein the mixing zone includes an inlet channel, a mixing channel and an outlet channel connected in sequence, wherein the mixing channel includes a plurality of first mixing channels a and a plurality of second mixing channels b, and the first mixing channels a and the second mixing channels b are alternately arranged in a cycle, wherein:

[0053] The first mixing channel a is divided into 7 modules, module 1 a1 is a channel with variable diameters at the front and back, with a hydraulic diameter of 1714 μm at the inlet and a channel height of 1.5 mm, a hydraulic diameter of 1150 μm at the outlet and a channel height of 1.45 mm, a straight-line distance between the inlet section and the outlet section of 2 mm, and the inclination of module 1 a1 is 45° with the plane where the inlet channel is located as the reference plane; the outlet of module 1 a1 is connected to module 2 a2, and module 2 a2 is a straight channel and is perpendicular to the reference plane , the channel width is 0.95mm, the height is 1.45mm, the length is 3mm, and the hydraulic diameter is 1150μm; a3 module 3, a4 module 4 and a5 module 5 are reflux areas, and the fluid flow direction at the connection between a3 module 3 and a2 module 2 is perpendicular to the fluid flow direction in a2 module 2; a4 module 4 is a mixed reflux area, and the fluids in the upper and lower layers of the flow channel are collected and mixed in a4 module 4 and then redistributed into two fluid flows, and the outflow The fluid flow direction is opposite to that in the a2 module 2, the inlet section width is 1mm, the height is 3mm, the outlet section width is 2mm, and the height is 1.5mm; the a5 module 5 is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1714μm, the outlet hydraulic diameter is 1183μm, and the height is 1.45mm. The straight-line distance between the inlet section and the outlet section is 1mm, and the fluid flowing out of the outlet flows to the a6 module 6; the a6 module 6 and the a2 module 2 are symmetrical along the central axis Arranged and kept parallel to each other, and the fluid flow direction in the a6 module 6 is consistent with the fluid flow direction in the a2 module 2, the channel width is 0.95mm, the height is 1.45mm, the length is 3mm, and the hydraulic diameter is 1150μm; the a7 module 7 is a channel with front and rear diameter changes, the hydraulic diameter at the inlet is 1150μm, the hydraulic diameter at the outlet is 1500μm, the straight-line distance between the inlet cross section and the outlet cross section is 2mm, and the fluid flowing out of the outlet enters the second mixing channel b for further mixing;

[0054] The second mixing channel B is divided into 7 modules, module B1 is a channel with variable diameters at the front and back, with a hydraulic diameter of 1714 μm at the inlet and a channel height of 1.5 mm, a hydraulic diameter of 1150 μm at the outlet and a channel height of 1.45 mm, a straight-line distance of 2 mm between the inlet section and the outlet section, and a slope of 135° with the plane where the inlet channel is located as the reference plane; the outlet of module B1 is connected to module B2, and module B2 is a straight channel perpendicular to the reference plane, with a width of 0 .95mm, 1.45mm high, 3mm long, and a hydraulic diameter of 1150μm; Modules b3, b4, and b5 are reflux areas, and the fluid flow direction at the connection between Module b3 and Module b2 is perpendicular to the fluid flow direction in Module b2; Module b4 is a mixed reflux area, and the fluids in the upper and lower layers of the flow channel are collected and mixed in Module b4 and then redistributed into two fluid flows, and the outflowing fluid flows in the same direction as the flow in Module b2. The flow direction of the fluid is opposite to that of the fluid, the inlet section is 1mm wide and 3mm high, the outlet section is 2mm wide and 1.5mm high; module b5 is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1714μm, the outlet hydraulic diameter is 1183μm, the height is 1.45mm, the straight-line distance between the inlet section and the outlet section is 1mm, and the fluid flowing out of the outlet flows to module b6; the module b6 and the module b2 are arranged symmetrically along the central axis and remain parallel to each other, and the fluid in the module b6 is The flow direction of the body is consistent with the flow direction of the fluid in the b2 module, the channel width is 0.95mm, the height is 1.45mm, the length is 3mm, and the hydraulic diameter is 1150μm; the b7 module is a channel with a front and rear diameter change, the hydraulic diameter at the inlet is 1150μm, the hydraulic diameter at the outlet is 1500μm, the straight-line distance between the inlet cross section and the outlet cross section is 2mm, and the fluid flowing out of the outlet enters the subsequent first mixing channel a for continued mixing or enters the reaction zone through the outlet channel for delayed reaction;

[0055] The inlet channel has three channels arranged in parallel with each other, namely, upper, middle and lower channels. The hydraulic diameter of the inlet channel is 1000 μm, the hydraulic diameter of the outlet channel is 1000 μm, and the length is 1 mm. After the materials are fully mixed, they flow out from the outlet channel to the reaction zone.

[0056] The reaction zone is a straight-through channel with a total length of 50 cm and a hydraulic diameter of 1000 μm;

[0057] The material of each of the above-mentioned fluid channels is Hastelloy.

[0058] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 5% by weight, the reaction pressure is normal pressure, the reaction temperature is 60°C, the flow rate and the reaction channel length are controlled by the metering pump so that the residence time is 30min, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 81.8%, and the product methyl thioglycolate selectivity is 85.7%.

[0059] Example 2

[0060] The microchannel reaction device used in this embodiment is the same as that in the embodiment.

[0061] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 5% by weight, the reaction pressure is normal pressure, the reaction temperature is 70°C, the flow rate and the reaction channel length are controlled by the metering pump to make the residence time 30min, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 85.0%, and the product methyl thioglycolate selectivity is 86.3%.

[0062] Example 3

[0063] The microchannel reaction device used in this embodiment is the same as that in the embodiment.

[0064] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography analysis. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 5% by weight, the reaction pressure is 0.2MPa, the reaction temperature is 80°C, the flow rate and the reaction channel length are controlled by the metering pump so that the residence time is 30min, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 88.1%, and the product methyl thioglycolate selectivity is 86.5%.

[0065] Example 4

[0066] The microchannel reaction device used in this embodiment is the same as that in the embodiment.

[0067] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 5% by weight, the reaction pressure is 0.2MPa, the reaction temperature is 90°C, the flow rate and the reaction channel length are controlled by the metering pump so that the residence time is 30min, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 92.1%, and the product methyl thioglycolate selectivity is 94.4%.

[0068] Example 5

[0069] The microchannel reaction device used in this embodiment is the same as that in the embodiment.

[0070] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography analysis. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 5% by weight, the reaction pressure is normal pressure, the reaction temperature is 60°C, the flow rate and the reaction channel length are controlled by the metering pump so that the residence time is 60 minutes, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is finally discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 87.5%, and the product methyl thioglycolate selectivity is 90.1%.

[0071] Example 6

[0072] The microchannel reaction device used in this embodiment is the same as that in the embodiment.

[0073] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography analysis. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 1% by weight, the reaction pressure is normal pressure, the reaction temperature is 60°C, the flow rate and the reaction channel length are controlled by the metering pump to make the residence time 30min, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is finally discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 80.5%, and the product methyl thioglycolate selectivity is 78.5%.

[0074] Example 7

[0075] The microchannel reaction device used in this embodiment is the same as that in the embodiment.

[0076] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 3% by weight, the reaction pressure is normal pressure, the reaction temperature is 60°C, the flow rate and the reaction channel length are controlled by the metering pump so that the residence time is 30min, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is finally discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 92.3%, and the product methyl thioglycolate selectivity is 87.8%.

[0077] Example 8

[0078] The microchannel reaction device used in this embodiment is the same as that in the embodiment.

[0079] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography analysis. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 8% by weight, the reaction pressure is normal pressure, the reaction temperature is 60°C, the flow rate and the reaction channel length are controlled by the metering pump so that the residence time is 30min, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is finally discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 92.3%, and the product methyl thioglycolate selectivity is 77.8%.

[0080] Example 9

[0081] Based on the microchannel reaction device of Example 1, the hydraulic diameter of the outlet channel is 1500 μm and the length is 1 mm; the total length of the straight channel of the reaction zone is 50 cm and the hydraulic diameter is 1500 μm.

[0082] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 5% by weight, the reaction pressure is normal pressure, the reaction temperature is 60°C, the flow rate and the reaction channel length are controlled by the metering pump to make the residence time 30min, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is finally discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 76.3%, and the product methyl thioglycolate selectivity is 76.8%.

[0083] Example 10

[0084] Based on the microchannel reaction device of Example 1, the hydraulic diameter of the outlet channel is 2000 μm and the length is 1 mm; the total length of the straight channel of the reaction zone is 50 cm and the hydraulic diameter is 2000 μm.

[0085] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 5% by weight, the reaction pressure is normal pressure, the reaction temperature is 60°C, the flow rate and the reaction channel length are controlled by the metering pump so that the residence time is 30 minutes, the molar ratio of methanol:thioglycolic acid is set to 3:1 by the metering pump, and the product is finally discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 71.8%, and the product methyl thioglycolate selectivity is 68.7%.

[0086] Embodiment 11

[0087] The microchannel reaction device used in this embodiment is the same as that in the embodiment.

[0088] The above-mentioned microchannel reaction device is used to synthesize methyl thioglycolate. After the raw materials are fully mixed in the mixing zone, they enter the reaction zone for reaction, and the products are discharged and tested by liquid chromatography. The raw materials are thioglycolic acid, methanol and p-toluenesulfonic acid. The reaction raw materials are transported by metering pumps respectively. Methanol enters from the upper channel and the lower channel of the inlet channel. After thioglycolic acid dissolves p-toluenesulfonic acid, it enters from the middle channel of the inlet channel. Among them, the catalyst concentration is 5% by weight, the reaction pressure is normal pressure, the reaction temperature is 60°C, the flow rate and the reaction channel length are controlled by the metering pump so that the residence time is 30 minutes, the molar ratio of methanol:thioglycolic acid is set to 4:1 by the metering pump, and the product is discharged through the outlet. The product analysis results show that the thioglycolic acid conversion rate is 85.8%, and the product methyl thioglycolate selectivity is 90.7%.

[0089] Example 12

[0090] On the basis of the microchannel reaction device of Example 1, only a plurality of first mixing channels a are arranged in the mixing channel of the mixing zone, but no second mixing channel b is arranged.

[0091] The process of synthesizing methyl thioglycolate was the same as that in the example. The product analysis results showed that the conversion rate of thioglycolic acid was 45.5%, and the selectivity of the product methyl thioglycolate was 69.2%.

[0092] Embodiment 13

[0093] On the basis of the microchannel reaction device of Example 1, only a plurality of second mixing channels b are arranged in the mixing channel of the mixing zone, but no first mixing channel a is arranged.

[0094] The process of synthesizing methyl thioglycolate was the same as that in the example. The product analysis results showed that the conversion rate of thioglycolic acid was 42.3% and the selectivity of the product methyl thioglycolate was 70.5%.

[0095] It can be seen from the results of the above embodiments that in the microchannel reaction device described in the present invention, by introducing a microscale flow structure with a specific structure, the mixing efficiency can be effectively improved, the back-mixing problem in the esterification reaction can be reduced, and the product conversion rate and selectivity can be improved.

[0096] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A microchannel reaction device, characterized in that: It includes a mixing zone and a reaction zone, wherein the mixing zone includes an inlet channel, a mixing channel and an outlet channel which are connected in sequence, wherein the mixing channel includes a plurality of first mixing channels (a) and a plurality of second mixing channels (b), and the first mixing channels (a) and the second mixing channels (b) are arranged alternately and cyclically, each of the first mixing channels (a) and each of the second mixing channels (b) has a microscale flow structure, and the reaction zone is a straight-through channel.

2. The microchannel reaction device according to claim 1, characterized in that: The inlet channel of the mixing zone has at least two channels arranged parallel to each other, and the reaction material enters the mixing channel vertically through the inlet channel.

3. The microchannel reaction device according to claim 2, characterized in that: The inlet channel of the mixing zone has three channels arranged in parallel with each other, and the hydraulic diameter of the inlet channel is 200-2000 μm and the length is 1-2 mm.

4. The microchannel reaction device according to any one of claims 1 to 3, characterized in that: The first mixing channel (a) has two layers of flow channels arranged symmetrically along the central axis, each layer of flow channels is divided into seven modules, the module a1 (1) is a channel with a front-to-rear diameter change, the hydraulic diameter at the inlet is 1371-2056 μm, the channel height is 0.5-2 mm, the hydraulic diameter at the outlet is 920-1380 μm, the channel height is 0.5-2 mm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3 mm, and the plane where the inlet channel is located is used as the reference plane, the slope of the module a1 (1) is 30-60°; the outlet of the module a1 (1) is connected to the module a2 (2), and the The a2 module (2) is a straight channel and is perpendicular to the reference plane, with a channel width of 0.5-1.5 mm, a height of 0.5-2 mm, a length of 1-5 mm, and a hydraulic diameter of 920-1380 μm; the a3 module (3), the a4 module (4) and the a5 module (5) are reflux areas, and the fluid flow direction at the connection between the a3 module (3) and the a2 module (2) is perpendicular to the fluid flow direction in the a2 module (2); the a4 module (4) is a mixing reflux area, and the fluids in the upper and lower layers of the flow channel are collected and mixed in the a4 module (4) and then recirculated. The new distribution is that two fluids flow out, and the flow direction of the outflowing fluid is opposite to the flow direction of the fluid in the a2 module (2), the inlet cross-section width is 0.5-2mm, the height is 1-4mm, and the outlet cross-section width is 0.5-2mm, and the height is 0.5-2mm; the a5 module (5) is a channel with front and rear diameter changes, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the a6 module (6); the a6 module (6) and the a2 module (2) are along the central axis. They are arranged symmetrically and maintained parallel to each other, and the fluid flow direction in the a6 module (6) is consistent with the fluid flow direction in the a2 module (2), the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; the a7 module (7) is a channel with a front and rear variable diameter, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross-section and the outlet cross-section is 1-3mm, and the fluid flowing out of the outlet enters the second mixing channel (b) for further mixing.

5. The microchannel reaction device according to any one of claims 1 to 4, characterized in that: The second mixing channel (b) has two layers of flow channels arranged symmetrically along the central axis, each layer of the flow channel is divided into seven modules, the b1 module (8) is a channel with a front-to-rear diameter change, the hydraulic diameter at the inlet is 1371-2056 μm, the channel height is 0.5-2 mm, the hydraulic diameter at the outlet is 920-1380 μm, the channel height is 0.5-2 mm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3 mm, and the plane where the inlet channel is located is used as the reference plane. The slope of the b1 module (8) is 120-150°; the outlet of the b1 module (8) is connected to the b2 module (9), and the b2 module ( 9) is a straight channel and is perpendicular to the reference plane, with a channel width of 0.5-1.5 mm, a height of 0.5-2 mm, a length of 1-5 mm, and a hydraulic diameter of 920-1380 μm; module b3 (10), module b4 (11) and module b5 (12) are reflux areas, and the fluid flow direction at the connection between module b3 (10) and module b2 (9) is perpendicular to the fluid flow direction in module b2 (9); module b4 (11) is a mixing reflux area, and the fluids in the upper and lower layers of the flow channel are collected and mixed in module b4 (11) and then redistributed into two streams of fluid flowing out. The outflowing fluid flows in the opposite direction to the fluid in the b2 module (9), the inlet cross-sectional width is 0.5-2mm, the height is 1-4mm, the outlet cross-sectional width is 0.5-2mm, and the height is 0.5-2mm; the b5 module (12) is a channel with a front-to-rear diameter change, the inlet hydraulic diameter is 1371-2056μm, the outlet hydraulic diameter is 946-1420μm, the straight-line distance between the inlet and the outlet is 0.5-2mm, and the fluid flowing out of the outlet flows to the b6 module (13); the b6 module (13) and the b2 module (9) are symmetrically arranged along the central axis and remain parallel to each other, and the The fluid flow direction in module b6 (13) is consistent with the fluid flow direction in module b2 (9), the channel width is 0.5-1.5mm, the height is 0.5-2mm, the length is 1-5mm, and the hydraulic diameter is 920-1380μm; module b7 (14) is a channel with a front and rear diameter change, the hydraulic diameter at the inlet is 920-1380μm, the hydraulic diameter at the outlet is 1200-1800μm, the straight-line distance between the inlet cross section and the outlet cross section is 1-3mm, and the fluid flowing out of the outlet enters the subsequent first mixing channel (a) for continued mixing or enters the reaction zone through the outlet channel for delayed reaction.

6. The microchannel reaction device according to any one of claims 1 to 5, characterized in that: The outlet channel of the mixing zone has a hydraulic diameter of 200-2000 μm and a length of 1-2 mm.

7. The microchannel reaction device according to any one of claims 1 to 6, characterized in that: The hydraulic diameter of the straight channel of the reaction zone is 200-2000 μm, preferably 800-1500 μm; the length of the straight channel of the reaction zone is 20-100 cm, preferably 50-100 cm; the straight channel of the reaction zone has the same diameter as the outlet channel of the mixing zone.

8. The microchannel reaction device according to any one of claims 1 to 7, characterized in that: The material of each fluid channel of the microchannel reaction device is independently selected from stainless steel 316L, 904 stainless steel, Hastelloy and silicon carbide ceramics.

9. A method for liquid phase esterification reaction, characterized in that: The method is implemented in the microchannel reaction device according to any one of claims 1 to 8, and comprises: injecting the reaction raw materials and the catalyst into the mixing zone through the inlet channel for mixing, and then entering the reaction zone for reaction.

10. The method according to claim 9, characterized in that The method is used for synthesizing methyl thioglycolate.

11. The method according to claim 10, characterized in that The reaction conditions include: temperature of 50-100° C., pressure of 0-0.3 MPa, and residence time of 30-90 min.

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