CN113926402A - Micro-channel reactor and application thereof - Google Patents
Micro-channel reactor and application thereof Download PDFInfo
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- CN113926402A CN113926402A CN202010609745.3A CN202010609745A CN113926402A CN 113926402 A CN113926402 A CN 113926402A CN 202010609745 A CN202010609745 A CN 202010609745A CN 113926402 A CN113926402 A CN 113926402A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D207/00—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom
- C07D207/02—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D207/18—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member
- C07D207/22—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D207/24—Oxygen or sulfur atoms
- C07D207/26—2-Pyrrolidones
- C07D207/263—2-Pyrrolidones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms
- C07D207/267—2-Pyrrolidones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to the ring nitrogen atom
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- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00781—Aspects relating to microreactors
- B01J2219/00783—Laminate assemblies, i.e. the reactor comprising a stack of plates
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00781—Aspects relating to microreactors
- B01J2219/00819—Materials of construction
- B01J2219/00822—Metal
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00781—Aspects relating to microreactors
- B01J2219/00819—Materials of construction
- B01J2219/00824—Ceramic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00781—Aspects relating to microreactors
- B01J2219/00891—Feeding or evacuation
Abstract
The invention discloses a micro-channel reactor, which comprises: a reaction substrate; the heat exchange substrate and the reaction substrates are alternately stacked, and a microchannel unit is formed between the adjacent reaction substrates and the heat exchange substrate, wherein the microchannel unit comprises a plurality of reaction area fluid channels which are arranged at intervals, and a porous medium inner member is arranged between the adjacent reaction area fluid channels; and raw material inlets respectively arranged at two opposite sides of the microchannel unit, wherein the raw material inlets are communicated with the fluid channel of the reaction zone, so that raw materials entering from the raw material inlets at two opposite sides form countercurrent contact in the fluid channel of the reaction zone through the porous medium inner member, and mass transfer and reaction occur; a collection assembly in communication with the reaction zone fluid passage for collecting reaction products. Also provides a reaction method and application by adopting the microchannel reactor.
Description
Technical Field
The invention relates to the field of microchannel devices, in particular to a microchannel reactor and application thereof.
Background
The microchannel technology is a process strengthening technology for carrying out chemical reaction, heat exchange, mixing and separation in a three-dimensional process fluid channel with micron-sized characteristic dimension, can obviously improve the heat and mass transfer efficiency and the space utilization rate, realizes accurate control on reaction conditions, and has intrinsic safety. In recent years, the microchannel reaction technology has been developed rapidly in the fields of fine chemical engineering and pharmaceutical chemical engineering.
Due to the characteristic that the microchannel reaction technology can realize high-efficiency conversion and continuous production, the method has very obvious advantages and very wide application prospect in the fine chemical synthesis process with severe thermal effect compared with the traditional batch kettle process. However, many heterogeneous reaction processes with complex processes exist in the fine chemical industry, the production processes of many high-added-value fine chemical products include various processes such as heat transfer, mixing, reaction, separation and even external field enhancement, and although precise regulation and control of the production process of the products can be realized in a microchannel reactor, the existing continuous flow synthesis technology does not have a very mature commercial product and process route in the aspect of heterogeneous system multi-process coupling.
US patent No. 5329021 discloses a method for synthesizing N-vinyl pyrrolidone, which utilizes a continuous contact tower reactor to realize the countercurrent contact of liquid phase pyrrolidone raw material and gas phase acetylene raw material, thereby realizing uniform temperature control in the reaction process, but the reaction residence time still needs 2-4 hours, thereby limiting the space-time yield of the reaction process, and the high pressure acetylene gas phase space exists above the reactor, therefore, the reactor still has a larger promotion space in the aspects of process efficiency and safety. European patent EP0703219a1 reports a process for the preparation of N-vinyl pyrrolidone by the replacement of acetylene with vinyl acetate, which improves the conventional gas-liquid process to a pure liquid phase process reaction, which is fast in reaction rate and can be completed in a second-order residence time, greatly reducing the reaction time. But a large amount of reaction heat is released in the reaction process, the temperature cannot be effectively controlled in the traditional reactor, and the normal and orderly reaction is influenced.
Disclosure of Invention
Aiming at the problems in the prior art, a first object of the present invention is to provide a microchannel reactor, which greatly improves the heat transfer efficiency in the reaction process by using the microscale effect, and can rapidly remove the heat generated in the reaction process by the alternating stacking combination of reaction substrates and heat exchange substrates, and simultaneously, two materials are in countercurrent contact through a porous medium material in the microscale space by a countercurrent reaction contact manner, so that rapid temperature runaway at the reaction inlet in the traditional parallel flow manner is avoided, and a gradient-free temperature field can be formed in the reaction region.
The second purpose of the invention is to provide a method for carrying out reaction by adopting the microchannel reactor.
A third object of the present invention is to employ the further application of the above reaction process.
The invention provides a microchannel reactor, which comprises:
a reaction substrate;
the heat exchange substrate and the reaction substrates are alternately stacked, and a microchannel unit is formed between the adjacent reaction substrates and the heat exchange substrate, wherein the microchannel unit comprises a plurality of reaction area fluid channels which are arranged at intervals, and a porous medium inner member is arranged between the adjacent reaction area fluid channels; and
raw material inlets respectively arranged at two opposite sides of the microchannel unit, wherein the raw material inlets are communicated with the fluid channel of the reaction zone, so that raw materials entering from the raw material inlets at two opposite sides form countercurrent contact in the fluid channel of the reaction zone through the porous medium inner member, and mass transfer and reaction occur;
a collection assembly in communication with the reaction zone fluid passage for collecting reaction products.
Preferably, the reaction substrate is configured with grooves, and the grooves form the microchannel unit after the reaction substrate is combined with the heat exchange substrate.
Preferably, the microchannel unit further comprises a distribution region fluid channel, and both ends of the distribution region fluid channel are respectively communicated with the raw material inlet and the reaction region fluid channel, and are used for distributing the raw material entering from the raw material inlet to the plurality of reaction region fluid channels.
Preferably, the heat exchanger further comprises a heat transfer medium inlet and a heat transfer medium outlet, and the heat transfer medium inlet and the heat transfer medium outlet are both communicated with the heat exchange base plate to realize temperature control of the heat exchange base plate.
Preferably, the collection assembly comprises a collection region fluid channel and a fluid outlet, and two ends of the collection region fluid channel are respectively communicated with the reaction region fluid channel and the fluid outlet for collecting reaction products.
Preferably, the number of the microchannel unit is one or more, and a plurality of the microchannel units are stacked and communicated with each other to increase the effective length of the fluid channel of the reaction zone.
Preferably, the hydraulic diameter of the fluid channel of the reaction zone is 200-;
the length of the reaction zone fluid channel is 1-20cm, preferably 5-15cm, more preferably 6-12 cm.
Preferably, the hydraulic diameter of the fluid channel of the distribution area is 300-;
the length of the distribution area fluid channel is 1-10cm, preferably 2-8cm, more preferably 4-6 cm.
Preferably, the hydrodynamic diameter of the distribution zone fluid channels is greater than or equal to the hydrodynamic diameter of the reaction zone fluid channels.
Preferably, the width of the porous medium internal member is 0.1 to 2 times the width of the reaction zone fluid channel, and preferably, the width of the porous medium internal member is 0.2 to 1 times the width of the reaction zone fluid channel.
Preferably, the hydraulic diameter of the micropores of the member in the porous medium is 10 to 100 μm, preferably 30 to 60 μm; the porosity is between 50% and 95%, preferably between 60% and 90%.
Preferably, the porous medium internals are selected from one or more of multi-mesh stainless steel plate internals, aluminum foam internals, iron foam internals, nickel foam internals, titanium foam internals and copper foam internals.
Preferably, the material of the heat exchange substrate and the reaction substrate is selected from one or more of metal and ceramic, preferably from one or more of alloy and ceramic, and more preferably from one or more of stainless steel 316L, Hastelloy C and silicon carbide ceramic.
Preferably, the thickness of the heat exchange substrate is 1-5cm, preferably 2-3 cm.
The invention also provides a method for carrying out reaction by adopting the microchannel reactor, which comprises the following steps:
different raw materials are respectively introduced into the fluid channel of the reaction zone from the raw material inlets at two opposite sides of the microchannel unit;
raw materials entering the fluid channel of the reaction zone from the raw material inlets at two opposite sides of the microchannel unit are in countercurrent contact through the porous medium internal member, and carry out mass transfer and reaction;
the reaction product is discharged through the collection assembly.
The application of the microchannel reactor to the rapid reaction with intrinsic reaction time less than 1min, preferably to the rapid reaction with intrinsic reaction time less than 1s, in particular to the reaction for synthesizing N-vinyl pyrrolidone by adopting the reaction method.
Further, the application of the reaction method is applied to an exothermic reaction with a chemical reaction heat of more than 100kJ/mol, preferably to an exothermic reaction with a reaction heat of more than 300 kJ/mol.
The reaction method of the microchannel reactor is particularly applied to the continuous process of a liquid-liquid reaction system with various rapid reactions and stronger heat effect, raw materials enter the microreactor to perform countercurrent mass transfer contact and perform the reaction process, a large amount of reaction heat in a reaction area can be rapidly removed by adopting a mode of adding a heat exchange substrate, a high-flux strong exothermic liquid phase reaction process can be realized within second-level residence time, and the method can be used in the field of strengthening the mixed reaction process of the microchannel technology, and has more obvious effect particularly on the process of synthesizing N-vinyl pyrrolidone by an acetylene method.
Drawings
The invention will be described in more detail hereinafter on the basis of embodiments and with reference to the accompanying drawings. Wherein:
FIG. 1 is a top view of a microchannel reactor reaction substrate according to the present invention;
FIG. 2 is a side view of a microchannel reactor of the present invention in superimposed relationship with two units;
FIG. 3 is a schematic view of a flow channel of a set of microchannel units of the microchannel reactor of the present invention;
FIG. 4 is a schematic view of the flow channels of two sets of microchannel units of the microchannel reactor of the present invention;
FIG. 5 is a schematic view of the flow channels of four sets of microchannel units in the microchannel reactor of the present invention.
In the figure: a raw material inlet of 1-pyrrolidone; 2-vinyl acetate raw material inlet; 3-a heat transfer medium inlet; 4-outlet of heat transfer medium; 5-a distribution area fluid channel; 5 a-pyrrolidone distribution channel; 5 b-vinyl acetate distribution channels; 6-a reaction zone fluid channel; 7-collection zone fluid channel; 8-a porous media inner member; 9-a fluid outlet; 10-a reaction substrate; 11-a heat exchange substrate; 12-a fluid channel; 12 a-pyrrolidone fluid channel; 12 b-vinyl acetate flow channel.
In the drawings, like parts are designated with like reference numerals, and the drawings are not to scale.
Detailed Description
In order to clearly illustrate the idea of the present invention, the present invention is described below with reference to the following embodiments.
In the description of the present invention, it should be noted that the terms "upper", "lower", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The invention provides a microchannel reactor, comprising: a reaction substrate;
the heat exchange substrate and the reaction substrates are alternately stacked, and a microchannel unit is formed between the adjacent reaction substrates and the heat exchange substrate, wherein the microchannel unit comprises a plurality of reaction area fluid channels which are arranged at intervals, and a porous medium inner member is arranged between the adjacent reaction area fluid channels; and
raw material inlets respectively arranged at two opposite sides of the microchannel unit, wherein the raw material inlets are communicated with the fluid channel of the reaction zone, so that raw materials entering from the raw material inlets at two opposite sides form countercurrent contact in the fluid channel of the reaction zone through the porous medium inner member, and mass transfer and reaction occur;
a collection assembly in communication with the reaction zone fluid passage for collecting reaction products.
A large amount of reaction heat generated in the reaction area can be removed quickly and efficiently through the reaction substrates and the heat exchange substrates which are alternately stacked; the micro-channel unit formed between the reaction substrate and the heat exchange substrate forms a micro-scale space structure of the reactor, and can form a micro-scale effect in the reaction process, the effect can greatly improve the heat transfer efficiency in the reaction process, and the heat in the process flow can be ensured to be rapidly removed through the synergistic effect formed by the heat exchange substrate, a non-gradient temperature field can be formed in the reaction area, and the high-flux strong heat release liquid phase reaction process can be effectively realized within the second-level retention time.
The porous medium inner member realizes a stable mass transfer process between two liquid-phase materials in a counter-current flow state through an internal micro-scale space structure, greatly increases the specific surface area of a mass transfer space, can efficiently remove heat generated by reaction while stabilizing the mass transfer process, and ensures the construction of a gradient-free temperature field in a reaction space.
By adopting the countercurrent reaction contact mode for the raw materials, countercurrent contact is carried out between the raw materials through the porous medium material in the micro-scale space structure, sharp temperature runaway of the traditional parallel flow mode at a reaction inlet is avoided, a temperature field without gradient can be formed in a reaction area, the violent effect of rapid reaction is effectively alleviated, and the mild and stable reaction is effectively ensured.
In addition, through a porous medium inner member arranged between the fluid channels of the reaction zone and the countercurrent contact formed at the part, the mass transfer and the reaction are relatively sufficient, so that the reaction is more direct and efficient; the product after reaction is collected by the collecting component communicated with the fluid channel of the reaction area, so that the further reaction of the reaction raw materials which are in contact in the fluid channel of the reaction area can be ensured, the reaction rate of the subsequent reaction is improved, the smooth reaction of the reaction materials in the microchannel unit is ensured, and different materials can be more fully and completely reacted.
According to the invention, the reaction substrate is provided with the precisely processed grooves, after the reaction substrate is combined with the heat exchange substrate, namely after the plane of the reaction substrate is pressed with the plane of the heat exchange substrate, the plurality of spaced grooves form micron-sized fluid channels, the reaction substrate is provided with the micro-channel unit of the reactor, the micro-channel unit forms a micro-scale space structure of the reactor and can form a micro-scale effect in the reaction process, the effect can greatly improve the heat transfer efficiency in the reaction process, and the heat in the process flow can be ensured to be rapidly removed through the synergistic effect formed by the heat exchange substrate, a gradient-free temperature field can be formed in the reaction area, and a high-flux strong heat release liquid phase reaction process can be effectively realized within the second-level residence time.
Specifically, the microchannel unit on the reaction substrate includes a distribution region fluid channel in addition to the reaction region fluid channel, and both ends of the distribution region fluid channel are respectively communicated with the raw material inlet and the reaction region fluid channel, and are used for distributing the raw material entering from the raw material inlet to the plurality of reaction region fluid channels. Through this kind of mode of setting up, can effectively disperse the material of difference, make the reaction material of difference constitute homogeneous system even relatively, make the material get into reaction zone after react more steady.
The heat exchange substrate is of a hollow structure, the heat transfer medium inlet and the heat transfer medium outlet are also arranged on the heat exchange substrate, and the heat transfer medium inlet and the heat transfer medium outlet are communicated with the heat exchange substrate so as to realize temperature control of the heat exchange substrate. More specifically, the heat transfer medium in the heat exchange base plate is connected with the external circulation cold-hot all-in-one machine arranged outside, so that the reaction heat removed by the heat transfer medium is cooled by external heat exchange equipment and then is recycled back to the inside of the heat exchange base plate, the temperature control range of-40-200 ℃ can be realized through the arrangement mode, the heat exchange effect of the microchannel reactor is effectively improved, the heat of the strong exothermic reaction can be quickly removed, and the heat accumulation in a reaction area during the strong exothermic reaction is avoided.
The collecting component comprises a collecting region fluid channel and a fluid outlet, wherein two ends of the collecting region fluid channel are respectively communicated with the reaction region fluid channel and the fluid outlet and are used for collecting reaction products. The reaction product can be effectively collected through the fluid channel in the collecting area, the influence on the continuous reaction of the reaction material in the reaction area is avoided, and the continuity of the whole reaction is improved.
Referring to fig. 3, the microchannel unit of the present invention may be a set, two sets of microchannel units in fig. 4 may be stacked, or four sets of microchannel units in fig. 5 may be stacked, and when the multiple sets are stacked, the microchannel units are communicated with each other to increase the effective length of the fluid channel in the reaction region. The setting mode improves the use flexibility of the micro-channel unit on one hand, and on the other hand, the use requirements under different reaction conditions can be met, so that the reaction of different systems can be conveniently carried out.
Starting from the micro-scale effect formed in the microchannel reactor, the invention has relevant requirements on the sizes and the lengths of the fluid channels of the reaction zone and the fluid channels of the distribution zone, specifically:
the hydraulic diameter of the fluid channel in the reaction area is 200-;
the length of the fluid channel in the reaction zone is 1-20cm, preferably 5-15cm, more preferably 6-12 cm.
The hydraulic diameter of the fluid channel of the distribution area is 300-;
the length of the distribution area fluid channel is 1-10cm, preferably 2-8cm, more preferably 4-6 cm.
And the hydraulic diameter of the distribution area fluid channel is larger than or equal to that of the reaction area fluid channel.
The purpose of the above arrangement is that, firstly, the reaction zone fluid channel can effectively form the micro-scale effect of the reactor in the diameter range, and the heat transfer efficiency of the reaction zone is ensured; and secondly, the distribution area fluid channel is in the diameter range, and the hydraulic diameter of the distribution area fluid channel is larger than or equal to that of the reaction area fluid channel, so that the materials in the distribution area can effectively and smoothly enter the reaction area for reaction, and the continuity of the reaction is reliably ensured.
In order to ensure the sufficient contact of the countercurrent materials, the hydraulic diameter and the porosity of micropores of the member in the porous medium need to be considered comprehensively, so that the materials can be in sufficient contact with the porous medium from different fluid channels, and the stability of the integral structure of the member in the porous medium needs to be considered. The size of the porous medium internals in the present invention should meet the following requirements:
the width of the porous medium inner member is 0.1-2 times of the width of the reaction zone fluid channel, preferably, the width of the porous medium inner member is 0.2-1 times of the width of the reaction zone fluid channel; preferably, the hydraulic diameter of the micropores of the member in the porous medium is 10 to 100 μm, preferably 30 to 60 μm; the porosity is between 50% and 95%, preferably between 60% and 90%. For the width requirement of the internal member of the porous medium, the full contact of different materials at the position of the internal member needs to be met, so that the effective mass transfer and reaction of different materials are realized, and the reaction is promoted to be more full and complete.
The materials of the heat exchange substrate and the reaction substrate are selected from one or more of metal and ceramic, preferably from one or more of alloy and ceramic, and more preferably from one or more of stainless steel 316L, Hastelloy C and silicon carbide ceramic; the thickness of the heat exchange substrate is 1-5cm, preferably 2-3 cm.
The metal, ceramic and other base materials have higher heat conductivity coefficients, so that heat can be removed from a reaction system more quickly and efficiently; the reaction substrate and the heat exchange substrate are arranged to be mutually attached metal or ceramic substrates, so that heat conduction can be more favorably carried out, the thermal resistance between the reaction substrate and the heat exchange substrate is reduced, and the heat transfer is smoother; the starting point of the thickness setting of the heat exchange substrate needs to meet the requirement of a hollow structure, and the heat exchange substrate is filled with a heat exchange medium, so that the heat generated at a very high speed can be effectively removed through the heat exchange medium.
The invention also provides a method for carrying out reaction by adopting the microchannel reactor, which comprises the following steps:
different raw materials are respectively introduced into the fluid channel of the reaction zone from the raw material inlets at two opposite sides of the microchannel unit;
raw materials entering the fluid channel of the reaction area from the raw material inlets at two opposite sides of the micro-channel unit are in countercurrent contact through the porous medium internal member, and high-efficiency mass transfer and reaction are carried out;
the reaction product is discharged through the collection assembly.
The method for carrying out the reaction through the microchannel reactor can carry out efficient mass transfer and reaction of different materials, greatly improve the reaction efficiency, timely remove heat generated by the reaction, effectively improve the reaction conditions and enable the reaction to be more complete. In addition, the reaction product can be discharged out of the reaction system in time through the collecting assembly, so that the reaction in the microchannel reactor is continuous, stable and efficient.
The microchannel reactor is suitable for the continuous process of a liquid-liquid reaction system with stronger heat effect, and is particularly suitable for a rapid reaction with intrinsic reaction time less than 1s and an exothermic reaction system which generates a large amount of reaction heat under the rapid reaction condition. The method can be effectively applied to exothermic reaction with the chemical reaction heat of more than 100kJ/mol, and is preferably applied to the reaction with the reaction heat of more than 300 kJ/mol. The following description will discuss a typical synthesis process of N-vinylpyrrolidone. It should be noted that, the synthesis reaction of N-vinyl pyrrolidone by using the microchannel reactor of the invention eliminates the existing heterogeneous reaction process, and the effective control of reaction temperature can be realized on the premise of greatly improving reaction efficiency by using a two-liquid-phase homogeneous material to enter the microchannel reactor.
Referring to fig. 1 in combination with fig. 2, the synthesis of N-vinyl pyrrolidone by the acetylene process using the microchannel reactor of the present invention comprises the following steps:
(1) pyrrolidone raw materials and vinyl acetate raw materials containing homogeneous catalysts enter a distribution area fluid channel 5 of a reaction substrate 10 from a pyrrolidone raw material inlet 1 and a vinyl acetate raw material inlet 2 respectively and are preheated in the distribution area fluid channel 5;
(2) the preheated pyrrolidone and vinyl acetate raw materials are in countercurrent contact in a reaction area fluid channel 6, and high-efficiency mass transfer and reaction are carried out through a porous medium inner member 8;
(3) two liquid phase raw materials are fully reacted in the reaction area flow channel 6 of the flow channel 12 and then are collected into the fluid outlet 9 through the collection area flow channel 7 to be discharged.
In the reaction process, a reaction substrate 10 and a heat exchange substrate 11 are pressed to form a micro-channel of the reactor, and in the reaction process, the heat exchange substrate is connected with an external circulation cooling and heating integrated machine through a heat exchange medium inlet 3 and a heat exchange medium outlet 4, so that the control of the reaction temperature is realized.
The distribution section fluid passage 5 includes a pyrrolidone distribution passage 5a and a vinyl acetate distribution passage 5 b.
The length of the pyrrolidone distribution channel is 1-10cm, preferably 2-8cm, more preferably 4-6 cm.
The length of the vinyl acetate distribution channel is 1-10cm, preferably 2-8cm, more preferably 4-6 cm.
The pyrrolidone distribution channel and the vinyl acetate distribution channel have the same length. In the reaction process, the fluid passages are mainly divided into a pyrrolidone fluid passage 12a and a vinyl acetate fluid passage 12b, two different reaction materials are introduced, and the flow directions of the two materials are opposite.
The preparation method of the pyrrolidone raw material containing the homogeneous catalyst in the reaction process comprises the following steps:
1. mixing a certain amount of potassium hydroxide and pyrrolidone, and quickly placing the mixture in a rotary evaporator;
2. starting a rotary evaporator, carrying out reduced pressure distillation at 120 ℃ for 2h under a vacuum environment (50mbar), and carrying out nitrogen purging once every 30min to remove residual moisture;
3. and after the reduced pressure distillation is finished, quickly taking out the liquid-phase product and sealing the liquid-phase product in a wide-mouth bottle for later use.
The technical content of the present invention is further illustrated by the following specific examples, but the present invention is not limited to the scope of the examples. The following examples are carried out in the microchannel reactor claimed in the present invention according to the requirements of the process of the present invention.
The following embodiments are all devices for synthesizing N-vinyl pyrrolidone by building a micro-channel reactor with reference to device schematic diagrams shown in fig. 1 and fig. 2, wherein the temperature of the micro-channel reaction substrate is controlled by a heat exchange substrate externally connected with a cooling and heating integrated machine, and crude N-vinyl pyrrolidone can be collected from a fluid outlet.
Example 1
(1) Device construction: the microchannel reactor main body is processed by stainless steel 316L, micron-sized notches are manufactured on a reaction substrate through precision machining, the plane of a heat exchange substrate and the reaction substrate are pressed and sealed to form micron-sized channels, porous sieve plate internals are arranged in the positions of adjacent reaction channels, and the specific arrangement and size are as follows: the hydraulic diameter of the fluid channel in the distribution area is 1200 microns, the total length is 5cm, the hydraulic diameter of the fluid channel in the reaction area is 500 microns, the total length is 10cm, the width of the internal component of the porous sieve plate arranged between the fluid channels in the adjacent reaction areas is equal to the width of the fluid channel in the reaction areas, the hydraulic diameter of the micropores is 50 microns, the porosity is 80%, the thickness of the heat exchange substrate is 2.5 cm, and the microchannel reactor in the embodiment comprises 2 layers of reaction substrates and 2 layers of heat exchange substrates.
(2) N-vinyl pyrrolidone synthesis: respectively conveying pyrrolidone containing a catalyst and a vinyl acetate liquid phase raw material by using a metering pump, wherein the mass fraction of a catalyst pyrrolidone potassium salt in the 2-pyrrolidone is 3%; setting the molar flow ratio of main raw materials in a metering pump as vinyl acetate: 2-pyrrolidone ═ 1: 1. Two materials are preheated to 20 ℃ in a distribution section of a microscale fluid channel and then enter a reaction section for pyrrolidone vinylation reaction, the temperature of a reaction area is controlled to be 10 ℃ through a heat exchange substrate, the reaction pressure is normal pressure, and the flow of a metering pump is adjusted and the residence time of the reaction materials in the reaction area is controlled to be 20 s. Collecting liquid phase product at fluid outlet of the microchannel reactor, and collecting 95-105 deg.C fraction by reduced pressure distillation at 50mbar to obtain N-vinylpyrrolidone crude product directly. The product analysis results showed that the conversion of 2-pyrrolidone was 98.7% and the selectivity of N-vinylpyrrolidone was 88.6%.
Example 2
All steps in this example are substantially the same as those in example 1, except that the hydrodynamic diameter of the distribution region fluid channel is 2000 μm, and the total length is 1 cm; the product analysis results showed that the conversion of 2-pyrrolidone was 93.2% and the selectivity to N-vinylpyrrolidone was 86.5%.
Example 3
All steps in this example are substantially the same as those in example 1, except that the distribution region fluid channel has a hydraulic diameter of 500 μm and a total length of 8 cm; the product analysis results show that the conversion rate of the 2-pyrrolidone is 97.2 percent, and the selectivity of the N-vinyl pyrrolidone is 81.2 percent.
Example 4
All steps in this example are substantially the same as those in example 1, except that the hydrodynamic diameter of the flow channel in the reaction zone is 300 μm, and the total length is 6 cm; the product analysis results showed that the conversion of 2-pyrrolidone was 93.9% and the selectivity to N-vinylpyrrolidone was 84.7%.
Example 5
All steps in this example are substantially the same as those in example 1, except that the hydrodynamic diameter of the reaction zone fluid channel is 800 μm, and the total length is 12 cm; the product analysis results showed that the conversion of 2-pyrrolidone was 96.3% and the selectivity of N-vinylpyrrolidone was 79.7%.
Example 6
All steps in this example are substantially the same as example 1 except that the width of the internal member of the perforated deck disposed between the fluid channels of adjacent reaction zones is 0.5 times the width of the fluid channels of the reaction zones; the product analysis results showed that the conversion of 2-pyrrolidone was 91.4% and the selectivity to N-vinylpyrrolidone was 78.5%.
Example 7
All the steps in the embodiment are basically the same as those in the embodiment 1, except that the micropore hydraulic diameter of the internal member of the porous sieve plate arranged between the fluid channels of the adjacent reaction areas is 100 microns, and the porosity is 60 percent; the product analysis results showed that the conversion of 2-pyrrolidone was 99.4% and the selectivity to N-vinylpyrrolidone was 68.9%.
Example 8
All the steps in the embodiment are basically the same as those in the embodiment 1, except that the micropore hydraulic diameter of the internal member of the porous sieve plate arranged between the fluid channels of the adjacent reaction areas is 10 microns, and the porosity is 90 percent; the product analysis results showed that the conversion of 2-pyrrolidone was 91.2% and the selectivity to N-vinylpyrrolidone was 87.9%.
Example 9
All the steps in this example are substantially the same as in example 1, except that the heat exchange substrate has a thickness of 5cm, and product analysis shows that the conversion of 2-pyrrolidone is 96.7% and the selectivity of N-vinyl pyrrolidone is 75.3%.
Example 10
All the steps in this example are substantially the same as those in example 1, except that the microchannel reactor in this example comprises 4 reaction substrates and 4 heat exchange substrates, and the product analysis results show that the conversion rate of 2-pyrrolidone is 99.4% and the selectivity of N-vinyl pyrrolidone is 88.2%.
Example 11
All the steps in this example are substantially the same as those in example 1, except that the microchannel reactor in this example comprises 1 reaction substrate layer and 1 heat exchange substrate layer, and the product analysis result shows that the conversion rate of 2-pyrrolidone is 97.9% and the selectivity of N-vinyl pyrrolidone is 89.8%.
Example 12
All the procedures in this example are substantially the same as those in example 1 except that the mass fraction of the catalyst, i.e., pyrrolidone potassium salt, in 2-pyrrolidone is 1%, and the results of product analysis show that the conversion of 2-pyrrolidone is 89.3% and the selectivity of N-vinylpyrrolidone is 89.2%.
Example 13
All the steps in this example are substantially the same as in example 1 except that the temperature in the reaction zone was controlled to 30 ℃ by the heat exchange substrate, and the product analysis results showed that the conversion of 2-pyrrolidone was 99.9% and the selectivity of N-vinylpyrrolidone was 67.3%.
Example 14
All the steps in this example are substantially the same as in example 1, except that by adjusting the flow rate of the metering pump and controlling the residence time of the reaction mass in the reaction zone to be 80s, the product analysis results show that the conversion of 2-pyrrolidone is 99.2% and the selectivity of N-vinylpyrrolidone is 83.6%.
Finally, it is to be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not intended to be limiting. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention, and these changes and modifications are to be considered as within the scope of the invention.
Claims (17)
1. A microchannel reactor, comprising:
a reaction substrate;
the heat exchange substrate and the reaction substrates are alternately stacked, and a microchannel unit is formed between the adjacent reaction substrates and the heat exchange substrate, wherein the microchannel unit comprises a plurality of reaction area fluid channels which are arranged at intervals, and a porous medium inner member is arranged between the adjacent reaction area fluid channels; and
raw material inlets respectively arranged at two opposite sides of the microchannel unit, wherein the raw material inlets are communicated with the fluid channel of the reaction zone, so that raw materials entering from the raw material inlets at two opposite sides form countercurrent contact in the fluid channel of the reaction zone through the porous medium inner member, and mass transfer and reaction occur;
a collection assembly in communication with the reaction zone fluid passage for collecting reaction products.
2. The microchannel reactor of claim 1, wherein the reaction substrate is configured with grooves that form the microchannel unit after the reaction substrate is bonded to the heat exchange substrate.
3. The microchannel reactor of claim 1, wherein the microchannel unit further comprises a distribution-zone fluid channel, both ends of the distribution-zone fluid channel respectively communicating with the raw material inlet and the reaction-zone fluid channel, for distributing the raw material entering from the raw material inlet to the plurality of reaction-zone fluid channels.
4. The microchannel reactor of claim 1, further comprising a heat transfer medium inlet and a heat transfer medium outlet, both of which are in communication with the heat exchange substrate to enable temperature control of the heat exchange substrate.
5. The microchannel reactor of claim 1, wherein the collection assembly comprises a collection zone fluid channel and a fluid outlet, the collection zone fluid channel having two ends respectively communicating with the reaction zone fluid channel and the fluid outlet for collecting reaction products.
6. The microchannel reactor of claim 1, wherein the number of the microchannel units is one or more, and a plurality of the microchannel units are stacked and communicated with each other to increase the effective length of the fluid channel of the reaction zone.
7. The microchannel reactor of claim 1, wherein the hydraulic diameter of the fluid channel of the reaction zone is 200-;
the length of the reaction zone fluid channel is 1-20cm, preferably 5-15cm, more preferably 6-12 cm.
8. The microchannel reactor of claim 7, wherein the hydraulic diameter of the distribution region fluid channel is 300-;
the length of the distribution area fluid channel is 1-10cm, preferably 2-8cm, more preferably 4-6 cm.
9. The microchannel reactor of claim 8, wherein the distribution zone fluid channels have a hydraulic diameter greater than or equal to the hydraulic diameter of the reaction zone fluid channels.
10. The microchannel reactor of claim 1, wherein the width of the porous media internals is from 0.1 to 2 times the width of the reaction zone fluidic channels, preferably from 0.2 to 1 times the width of the reaction zone fluidic channels.
11. The microchannel reactor of claim 1, wherein the pores of the porous media internals have a hydraulic diameter of 10-100 μ ι η, preferably 30-60 μ ι η; the porosity is between 50% and 95%, preferably between 60% and 90%.
12. The microchannel reactor of claim 1, wherein the porous media internals are selected from one or more of a multi-mesh stainless steel plate internals, an aluminum foam internals, an iron foam internals, a nickel foam internals, a titanium foam internals, and a copper foam internals.
13. The microchannel reactor of claim 1, wherein the material of the heat exchange substrate and the reaction substrate is selected from one or more of metals and ceramics, preferably from one or more of alloys and ceramics, more preferably from one or more of stainless steel 316L, hastelloy C, and silicon carbide ceramics.
14. The microchannel reactor of claim 1, wherein the heat exchange substrate has a thickness of 1-5cm, preferably 2-3 cm.
15. A method of conducting a reaction using the microchannel reactor of any one of claims 1-14, comprising the steps of:
different raw materials are respectively introduced into the fluid channel of the reaction zone from the raw material inlets at two opposite sides of the microchannel unit;
raw materials entering the fluid channel of the reaction zone from the raw material inlets at two opposite sides of the microchannel unit are in countercurrent contact through the porous medium internal member, and carry out mass transfer and reaction;
the reaction product is discharged through the collection assembly.
16. Use of a microchannel reactor according to any of claims 1 to 14 or a process according to claim 15, wherein the microchannel reactor is used for fast reactions with intrinsic reaction times of less than 1min, preferably for very fast reactions with intrinsic reaction times of less than 1s, in particular for the synthesis of N-vinylpyrrolidone.
17. Use of a microchannel reactor according to any one of claims 1-14 or a method according to claim 15, wherein the microchannel reactor is used for exothermic reactions with a heat of chemical reaction of more than 100kJ/mol, preferably for exothermic reactions with a heat of reaction of more than 300 kJ/mol.
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