Microfluidic reaction device and method for preparing alkyl sulfonic acid

Abstract

The application provides a micro-channel reaction device and method for preparing alkyl sulfonic acid. The device comprises a micro-reactor and a heat exchanger for keeping the micro-reactor at a set temperature; the micro-reactor is provided with a micro-flow channel, the pore size of the micro-flow channel is 2-5 mm; the micro-flow channel has a reactant inlet and a product outlet; the micro-flow channel in the micro-reactor has a liquid carrying capacity of 800-1200 mL. Compared with the prior art, the application has the beneficial effects of high reaction efficiency, short production cycle, few impurities in the product, high product yield, easy mass production, improved operation safety, enhanced equipment sustainability, and reduced equipment maintenance cost.

Description

Technical Field

[0001] This application relates to the field of chemical technology, specifically to a microfluidic reaction apparatus and method for preparing alkyl sulfonic acids. Background Technology

[0002] Alkyl sulfonic acids are liquid acids. The main methods for synthesizing alkyl sulfonic acids include: methyl thiocyanate oxidation, air oxidation, methanesulfonyl chloride hydrolysis, and dimethyl disulfide oxidation. Among these, the methyl thiocyanate oxidation method is simple and technically proficient, but it involves excessive nitric acid, which is wasteful and causes environmental pollution. Furthermore, the post-processing involves a barium salt step, resulting in high production costs. The air oxidation method has low yields and requires significant raw material input. The methanesulfonyl chloride hydrolysis method is costly and corrodes equipment. The dimethyl disulfide oxidation method generates a large amount of heat and has low safety.

[0003] Currently, the synthesis method mainly uses batch reactors. The common approach is to combine batch reactors with dimethyl disulfide oxidation to prepare alkyl sulfonic acids. However, batch reactors have a large liquid holdup, making it difficult to control the reaction temperature. At low temperatures, the reaction rate is slow, while at high temperatures, there is a risk of explosion, posing significant safety hazards. Furthermore, reaction byproducts corrode production equipment, and the process suffers from low yields, making it unsuitable for large-scale production.

[0004] Therefore, the equipment and methods for synthesizing alkyl sulfonic acids still need improvement. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this application is to provide a microfluidic reaction device and method for preparing alkyl sulfonic acids, so as to solve the problems mentioned in the background art.

[0006] In a first aspect, the present invention provides a microfluidic reaction device, including a microreactor and a heat exchanger for maintaining a set temperature of the microreactor;

[0007] The microreactor is provided with microfluidic channels, and the pore size of the microfluidic channels is 2-5 mm;

[0008] The microfluidic channel has a reactant inlet and a product outlet;

[0009] The liquid loading capacity of the microfluidic channel in the microreactor is 800-1200 mL.

[0010] The microfluidic reaction apparatus provided by this invention is used to prepare alkyl sulfonic acids. In different embodiments, the pore size of the microfluidic channel can be 2 mm, 3 mm, 4 mm, or 5 mm. In different embodiments, the liquid carrying capacity of the microfluidic channel can be 800 mL, 900 mL, 1000 mL, 1100 mL, 1200 mL, etc.

[0011] In this microreactor, the microfluidic channels are sealed pipes, meaning they are interconnected but sealed relative to the outside. The microfluidic channels can be arranged in a flat plate or through a perforated design. They are generally arranged in parallel rows or columns within the microreactor, with adjacent rows or columns connected. Each row of microfluidic channels contains multiple flow-encircling columns, or the flow-encircling columns are evenly distributed within each row. In some embodiments, the distance between each row of microfluidic channels is no greater than 1.5 times and no less than 0.5 times the cross-sectional area of ​​the microfluidic channel, such as 0.5 times, 0.8 times, 1 time, 1.2 times, 1.5 times, etc.

[0012] Optionally, the microfluidic channels are arranged in rows or columns within the microreactor. The shape of the microfluidic channels can be configured as at least one of various shapes, such as cylindrical, heart-shaped, triangular, quadrilateral, and polygonal. Preferably, except for the connecting portions between rows or columns, the microfluidic channels are arranged in a rhomboid pattern. Further, the rhomboid arrangement is configured such that the channels meet at angles not exceeding 90°. Optionally, a flow-encircling column is provided in the middle portion of each rhomboid microfluidic channel. Optionally, the flow-encircling column is rhomboid in shape, and the side length of the rhomboid of the flow-encircling column is 1 / 3 to 2 / 3 of the side length of the rhomboid microfluidic channel. Further, the corresponding sides of the rhomboid of the flow-encircling column and the rhomboid of the microfluidic channel are parallel to each other. Further, adjacent rows or columns of rhomboid microfluidic channels are interlocked. Furthermore, the distance between the opposite sides of the microfluidic channels in adjacent rows or columns is 20%-60% of the distance between the opposite sides of the rhombus, such as 20%, 30%, 40%, 45%, 50%, 55%, 60%, etc.

[0013] In some embodiments, the rhombuses are arranged at 60° angles. In some embodiments, they are arranged at 80° angles. In some embodiments, they are arranged at 90° angles. The cross-sectional area of ​​the connecting portion of the rhombuses is substantially the same as the area connecting the rows or columns. Generally, the connecting portion between rows or columns is a pipe.

[0014] "Basic" or "roughly" refers to a difference of no more than 10%.

[0015] Furthermore, the microfluidic reactor also includes a temperature controller, which controls the cooling medium rate in the heat exchanger by monitoring the temperature of the microreactor, thereby achieving the purpose of controlling the temperature of the microreactor.

[0016] In this invention, the temperature controller samples and monitors the temperature of the microreactor in real time through a temperature sensor. If the temperature exceeds the preset temperature, the temperature controller issues a switching command to control the cooling medium rate in the heat exchanger to reach the preset temperature range. If the temperature does not exceed the preset temperature, the cooling medium rate in the heat exchanger proceeds according to the setting.

[0017] In this invention, multiple temperature controllers can be set, or a single temperature controller can be set, or the temperature controller itself can be equipped with multiple sensors to detect the temperature of different parts of the microreactor or different microreactors.

[0018] Furthermore, the microreactor includes 13-15 plate-shaped microreactors, and the heat exchanger includes 15-17 plate-shaped heat exchangers, with the plate-shaped microreactors disposed between the plate-shaped heat exchangers;

[0019] The microfluidic channels in the sheet-like microreactors are interconnected, and the microfluidic channels between adjacent sheet-like microreactors are interconnected.

[0020] The heat exchange channels of the plate heat exchanger may or may not be connected.

[0021] If the microfluidic channels in the sheet-like microreactor are arranged in rows, the channels can be connected between adjacent rows or between two adjacent rows. If they are connected in units of two rows, the two rows first merge at their two ends and then connect to each other. Specifically, for example, starting from the first row at the inlet, the end of the first row connects to the nearest end of the second row, then the other end of the second row connects to the nearest ends of the third and fourth rows, the other ends of the third and fourth rows merge, and then connects to the nearest ends of the fifth and sixth rows; and so on. Preferably, if the microfluidic channels in the sheet-like microreactor are arranged in rows, then at least 50% of the microfluidic channels are connected in units of two adjacent rows.

[0022] Similarly, if the microfluidic channels in the sheet-like microreactor are arranged in rows, the communication between the microfluidic channels can be between adjacent rows or between two adjacent rows. The communication between rows is the same as that described above for row-like arrangement. Preferably, if the microfluidic channels in the sheet-like microreactor are arranged in rows, then 10%-20% of the microfluidic channels are connected in units of two rows.

[0023] In the microreactor, adjacent sheet-like microreactors can have the same microfluidic channel orientation, such as all being row-oriented, all being column-oriented, or having alternating row-oriented and column-oriented orientations. However, for more thorough mixing and reaction of the reaction liquid in the microreactor, preferably, at least 80% of the microfluidic channels in the microreactor are arranged vertically.

[0024] Furthermore, the sheet-like microreactors in the microreactor are arranged in sequence as a unit of one sheet-like microreactor as defined in (a) and multiple repeats of sheet-like microreactors as defined in (b) plus sheet-like microreactors as defined in (c):

[0025] (a) The microfluidic channels are sheet-like microreactors arranged in rows, wherein the middle 50%-60% of the microfluidic channels are connected in two rows, and the microfluidic channels in the inlet and outlet are connected in a single row. Furthermore, the ratio of the number of microfluidic channel rows in the inlet to the number of microfluidic channel rows in the outlet is 1:2-3.

[0026] (b) The microfluidic channels are sheet-like microreactors arranged in rows, with each microfluidic channel connected in units of two rows;

[0027] (c) The microfluidic channels are arranged in rows of sheet-like microreactors, wherein the inlet microfluidic channels are connected in pairs, and the rest are connected in single rows.

[0028] In this context, the arrangement of sheet-like microreactors within a microreactor, with multiple repetitions defined by (a) and (b) plus (c) as units, refers to a sheet-like microreactor defined by (a) and multiple repetitions defined by (b) + (c). Each repetition defined by (b) plus (c) is a repetition of (b) and (c) as a unit. For example, if a microreactor comprises 13-15 sheet-like microreactors, when the microreactor comprises 13 sheet-like microreactors, the sheet-like microreactors within the microreactor are arranged sequentially with one (a) and six sheet-like microreactors defined by (b) and (c); when the microreactor comprises 15 sheet-like microreactors, the sheet-like microreactors within the microreactor are arranged sequentially with one (a) and seven sheet-like microreactors defined by (b) and (c).

[0029] Preferably, the microreactor comprises 13-15 sheet-like microreactors, wherein the number of sheet-like microreactors is odd.

[0030] The reactant inlet and product outlet of the microreactor are located at opposite ends of the microfluidic channel. In some embodiments, the reactant inlet and product outlet of the microreactor are located on opposite sides of the microreactor, or at the furthest edges of adjacent sides.

[0031] Furthermore, in this invention, the microreactor and the heat exchanger are spaced apart to better control the temperature of the microreactor. In some embodiments, the cross-section of the microfluidic channels in the microreactor is rhomboid, circular, or near-circular (the ratio of the major to minor axis is no greater than 1.2), as described above, and will not be repeated here.

[0032] If the microfluidic channels of the sheet-like microreactor are hollowed out or largely hollowed out, the two sides of the sheet-like microreactor bulge outwards. Correspondingly, the heat exchanger is shaped to fit the microreactor, allowing them to adhere closely and cover the sides of the sheet-like microreactor, achieving a larger contact area and faster heat dissipation. In some embodiments, the heat exchanger consists of rows of parallel pipes connected end-to-end, with pipe diameters ranging from 0.5 to 1.5 cm. For example, in some embodiments, the pipe diameters are 0.5 cm, 0.8 cm, 1.0 cm, 1.2 cm, 1.5 cm, etc. Flow-encircling columns are also uniformly arranged within the pipes of the heat exchanger. The distance between the rows of parallel pipes is 1 / 4 to 1 / 8 of the pipe diameter.

[0033] In different implementations, the microreactor may include 13, 14, or 15 plate-shaped microreactors; in different implementations, the heat exchanger may include 15, 16, or 17 plate-shaped heat exchangers.

[0034] The plate-shaped microreactors and plate-shaped heat exchangers are stacked together, with the plate-shaped microreactors located between the plate-shaped heat exchangers. In this way, plate-shaped heat exchangers are set on both sides of the plate-shaped microreactors, which facilitates the timely dissipation of heat from the plate-shaped microreactors.

[0035] Multiple sheet-like microreactors are connected in series via microfluidic channels within them. The heat exchange channels of the sheet-like heat exchanger may or may not be connected. Even with multiple sheet-like microreactors, the reactant inlet and product outlet of each microreactor are located at the beginning and end of all the series-connected microfluidic channels, respectively. In some embodiments, the microreactor comprises multiple sheet-like microreactors, with the reactant inlet and product outlet located on the first and last stacked sheet-like microreactors, respectively.

[0036] In some embodiments, the microreactor includes a primary reaction zone and a secondary reaction zone connected in sequence, wherein the primary reaction zone has a liquid load of 90%-110% of that of the secondary reaction zone.

[0037] The microreactor consists of a primary reaction zone and a secondary reaction zone connected in series. Since the sheet-like microreactors are similar, approximately half of the sheet-like microreactors connected in series constitute the primary reaction zone, and the remainder constitute the secondary reaction zone.

[0038] For example, if a microreactor consists of 13 sheet-like microreactors, then the first 6 or 7 sheet-like microreactors are the primary reaction zone, and the rest are the secondary reaction zone.

[0039] For example, if a microreactor consists of 14 sheet-like microreactors, then the first 7 or the first 7 sheet-like microreactors are the primary reaction zone, and the rest are the secondary reaction zone.

[0040] For example, if a microreactor consists of 15 sheet-like microreactors, then the first 7 or 8 sheet-like microreactors are the primary reaction zone, and the rest are the secondary reaction zone.

[0041] In this invention, the 13-15 sheet-like microreactors are the same or similar in size, thickness, material, pore size of the microfluidic channels, and liquid loading capacity of the microfluidic channels.

[0042] Therefore, for multiple sheet-like microreactors connected in series, they are divided into two reaction zones. In the primary reaction zone, the sheet-like microreactors are arranged as follows: In the first sheet-like microreactor, rows 1-3 from the reactant inlet are connected in a single row, the middle section is connected in two-row units, and rows 2-5 at the outlet are connected in a single row. The second, third, and subsequent sheet-like microreactors, up to the sixth, seventh, or eighth sheet-like microreactor, are sequentially connected with each other. Sheet-like microreactors are arranged with a main connection in two-row units (no less than 75% of the microfluidic channels are connected in two-row units, e.g., all microfluidic channels are connected in two-row units) and sheet-like microreactors are arranged alternately with a main connection in one-row units (no more than 10% of the microfluidic channels are connected in one-row units, e.g., only one set of microfluidic channels is connected in two-row units). Optionally, the second sheet-like microreactor... In the sixth and seventh sheet-like microreactors, the microfluidic channels in adjacent sheet-like microreactors are arranged vertically. That is, in one adjacent sheet-like microreactor, the microfluidic channels are arranged in parallel or substantially parallel rows, while in another sheet-like microreactor, the microfluidic channels are arranged in parallel or substantially parallel columns. Furthermore, sheet-like microreactors primarily connected in two rows are arranged in parallel or substantially parallel rows, while those primarily connected in one column are arranged in parallel or substantially parallel columns. The final sheet-like microreactor is equipped with a product outlet.

[0043] The sheet-like microreactors in the secondary reaction zone are set up in the same manner as those in the primary reaction zone.

[0044] Optionally, each reaction zone is equipped with at least one of the aforementioned temperature controllers to control the temperature of each reaction zone. Similarly, the temperature controllers may be equipped with multiple sensors to detect the temperature of different sheet-like microreactors or different parts of the sheet-like microreactors, thereby controlling the temperature in different reaction zones.

[0045] Optionally, the temperature of the primary reaction zone is controlled at 60-80℃, and the temperature of the secondary reaction zone is controlled at 80-100℃. In different embodiments, the temperature of the primary reaction zone can be controlled at 60℃, 70℃, 75℃, and 80℃, etc. Similarly, in different embodiments, the temperature of the secondary reaction zone can be controlled at 80℃, 85℃, 90℃, 95℃, and 100℃, etc.

[0046] Furthermore, in this invention, the heat exchanger is provided with heat exchange channels, the aperture of which is 0.5-1.5 cm. The heat exchange channels in the heat exchanger are arranged in parallel columns, with adjacent columns connected. For example, starting from the first column at the inlet, the end of the first column connects to the closest end of the second column, and then the other end of the second column connects to the closest end of the third column; and so on. If all the heat exchange channels in the heat exchanger are connected in series, then the starting end of all heat exchange channels is the cooling medium inlet, and the ending end is the cooling medium outlet. In some embodiments, the inlet and outlet of the heat exchanger are located on opposite sides of the heat exchanger body, or at the furthest edges of adjacent sides. If multiple heat exchangers are connected in series, for stacked heat exchangers, the cooling medium inlet is usually located on the first heat exchanger, while the cooling medium outlet is usually located on the last heat exchanger.

[0047] In this invention, the heat exchange channels in the heat exchanger are sealed pipes, meaning that the heat exchange channels are interconnected but sealed relative to the outside. The cross-section of the heat exchange channels is circular or approximately circular. The heat exchange channels can be arranged in a flat plate or be hollowed out. Each column of heat exchange channels is provided with multiple flow-around columns, or the flow-around columns are evenly distributed in each row of heat exchange channels.

[0048] In some implementations, the distance between each heat exchange channel is no more than 1.5 times and no less than 0.5 times the cross-section of the heat exchange channel, such as 0.5 times, 0.8 times, 1 time, 1.2 times, 1.5 times, etc.

[0049] To achieve cooling more quickly and stably, optionally, there are two plate heat exchangers between the last plate microreactor in the primary reaction zone and the first plate microreactor in the secondary reaction zone.

[0050] Optionally, the microfluidic channels within the microreactor are made of silicon carbide. The silicon carbide microfluidic channels are less susceptible to corrosion, enhancing the equipment's sustainable utilization and reducing maintenance costs.

[0051] Furthermore, the microfluidic reaction device also includes a cover plate located on the surface of the microreactor.

[0052] Furthermore, the microfluidic reactor further includes at least one of the following:

[0053] A premixing unit is connected to the inlet of the microreactor and is used to mix the raw materials entering the microreactor.

[0054] A reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the premixing unit or the inlet of the microreactor;

[0055] An extraction unit is connected to the microreactor.

[0056] In some embodiments, the microfluidic reactor further includes a premixing unit connected to the inlet of the microreactor, the premixing unit being used to premix the raw materials entering the microreactor;

[0057] and / or a reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the premixing unit or the inlet of the microreactor.

[0058] In some embodiments, the microfluidic reactor further includes a premixing unit connected to the inlet of the microreactor. The premixing unit is used to mix the raw materials entering the microreactor. The mixing method and apparatus of the premixing unit are not particularly limited, as long as they achieve a certain mixing effect; the specific structure is not particularly limited. For example, the premixing unit can be set up separately or on a cover plate. The premixing unit is used to input different reactants and to mix them. The premixing unit can be a pipe or a container, and mixing can be achieved by inverting or rotating the container itself, or by an external stirrer. After the different reactants are mixed by the premixing unit, they are then fed into the microreactor through the reactant inlet.

[0059] In some embodiments, the microfluidic reactor further includes a reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the inlet of the microreactor. In some embodiments, the reflux unit is a pipeline capable of controlling the flow rate, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the inlet of the microreactor, with the flow rate of the liquid in the pipeline controlled by a flow rate control device on the pipeline.

[0060] In some embodiments, the microfluidic reactor further includes a premixing unit connected to the inlet of the microreactor, the premixing unit being used to mix the raw materials entering the microreactor;

[0061] A reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the premixing unit.

[0062] In some embodiments, the microfluidic reactor further includes an extraction unit connected to the outlet of the microreactor.

[0063] The extraction unit is used to further process the product exiting the microreactor to achieve purification. The extraction unit may include crude extraction and fine extraction, both of which generally employ a batch reactor.

[0064] Another aspect of the present invention provides a method for preparing alkyl sulfonic acid using the above-described microfluidic reaction apparatus, comprising:

[0065] An alkyl disulfide solution, a self-catalyst solution, and an oxidant solution are supplied to the microfluidic channel in the microreactor to carry out a microfluidic reaction in order to obtain the alkyl sulfonic acid.

[0066] When preparing alkyl sulfonic acids using a microfluidic reactor with a large pore size, the inventors discovered that the rapid reaction of the raw material solution generated a large amount of heat, making the microfluidic reactor prone to cracking, thus limiting its practicality and posing significant safety hazards. Through numerous trials and experiments, the inventors developed a microfluidic reactor that can be used for a long time, and also achieves a high yield of alkyl sulfonic acids.

[0067] Specifically, regarding microfluidic reaction devices:

[0068] A microfluidic reactor includes a microreactor and a heat exchanger for maintaining a set temperature in the microreactor;

[0069] The microreactor is provided with microfluidic channels, and the pore size of the microfluidic channels is 2-5 mm;

[0070] The microfluidic channel has a reactant inlet and a product outlet;

[0071] The liquid loading capacity of the microfluidic channel in the microreactor is 800-1200 mL.

[0072] The pore size of the microfluidic channel can be 2mm, 3mm, 4mm, or 5mm; the liquid carrying capacity of the flow channel can be 800mL, 900mL, 1000mL, 1100mL, 1200mL, etc.

[0073] In a microreactor, microfluidic channels are sealed conduits, meaning they are interconnected but sealed relative to the outside environment. Microfluidic channels can be housed in flat plates or perforated structures. They are generally arranged in parallel rows or columns within the microreactor, with adjacent rows or columns interconnected. Each row of microfluidic channels contains multiple flow-encircling columns, or the flow-encircling columns are evenly distributed within each row. In some embodiments, the distance between rows of microfluidic channels is no greater than 1.5 times and no less than 0.5 times the cross-sectional area of ​​the microfluidic channel, such as 0.5 times, 0.8 times, 1 time, 1.2 times, 1.5 times, etc.

[0074] Optionally, the microfluidic channels are arranged in rows or columns within the microreactor. The shape of the microfluidic channels can be configured as at least one of various shapes, such as cylindrical, heart-shaped, triangular, quadrilateral, and polygonal. Preferably, except for the connecting portions between rows or columns, the microfluidic channels are arranged in a rhomboid pattern. Further, the rhomboid arrangement is configured such that the channels meet at angles not exceeding 90°. Optionally, a flow-encircling column is provided in the middle portion of each rhomboid microfluidic channel. Optionally, the flow-encircling column is rhomboid in shape, and the side length of the rhomboid of the flow-encircling column is 1 / 3 to 2 / 3 of the side length of the rhomboid microfluidic channel. Further, the corresponding sides of the rhomboid of the flow-encircling column and the rhomboid of the microfluidic channel are parallel to each other. Further, adjacent rows or columns of rhomboid microfluidic channels are interlocked. Furthermore, the distance between the opposite sides of the microfluidic channels in adjacent rows or columns is 20%-60% of the distance between the opposite sides of the rhombus, such as 20%, 30%, 40%, 45%, 50%, 55%, 60%, etc.

[0075] In some embodiments, the rhombuses are arranged at 60° angles. In some embodiments, they are arranged at 80° angles. In some embodiments, they are arranged at 90° angles. The cross-sectional area of ​​the connecting portion of the rhombuses is substantially the same as the area connecting the rows or columns. Generally, the connecting portion between rows or columns is a pipe.

[0076] "Basic" or "roughly" refers to a difference of no more than 10%.

[0077] Furthermore, the microfluidic reactor also includes a temperature controller, which controls the cooling medium rate in the heat exchanger by monitoring the temperature of the microreactor, thereby achieving the purpose of controlling the temperature of the microreactor.

[0078] In this invention, the temperature controller samples and monitors the temperature of the microreactor in real time through a temperature sensor. If the temperature exceeds the preset temperature, the temperature controller issues a switching command to control the cooling medium rate in the heat exchanger to reach the preset temperature range. If the temperature does not exceed the preset temperature, the cooling medium rate in the heat exchanger proceeds according to the setting.

[0079] In this invention, multiple temperature controllers can be set, or a single temperature controller can be set, or the temperature controller itself can be equipped with multiple sensors to detect the temperature of different parts of the microreactor or different microreactors.

[0080] Furthermore, the microreactor includes 13-15 plate-shaped microreactors, and the heat exchanger includes 15-17 plate-shaped heat exchangers, with the plate-shaped microreactors disposed between the plate-shaped heat exchangers;

[0081] The microfluidic channels in the sheet-like microreactors are interconnected, and the microfluidic channels between adjacent sheet-like microreactors are interconnected.

[0082] The heat exchange channels of the plate heat exchanger may or may not be connected.

[0083] If the microfluidic channels in the sheet-like microreactor are arranged in rows, the channels can be connected between adjacent rows or between two adjacent rows. If they are connected in units of two rows, the two rows first merge at their two ends and then connect to each other. Specifically, for example, starting from the first row at the inlet, the end of the first row connects to the nearest end of the second row, then the other end of the second row connects to the nearest ends of the third and fourth rows, the other ends of the third and fourth rows merge, and then connects to the nearest ends of the fifth and sixth rows; and so on. Preferably, if the microfluidic channels in the sheet-like microreactor are arranged in rows, then at least 50% of the microfluidic channels are connected in units of two adjacent rows.

[0084] Similarly, if the microfluidic channels in the sheet-like microreactor are arranged in rows, the communication between the microfluidic channels can be between adjacent rows or between two adjacent rows. The communication between rows is the same as that described above for row-like arrangement. Preferably, if the microfluidic channels in the sheet-like microreactor are arranged in rows, then 10%-20% of the microfluidic channels are connected in units of two rows.

[0085] In the microreactor, adjacent sheet-like microreactors can have the same microfluidic channel orientation, such as all being row-oriented, all being column-oriented, or having alternating row-oriented and column-oriented orientations. However, for more thorough mixing and reaction of the reaction liquid in the microreactor, preferably, at least 80% of the microfluidic channels in the microreactor are arranged vertically.

[0086] Furthermore, the sheet-like microreactors in the microreactor are arranged in sequence as a unit of one sheet-like microreactor as defined in (a) and multiple repeats of sheet-like microreactors as defined in (b) plus sheet-like microreactors as defined in (c):

[0087] (a) The microfluidic channels are sheet-like microreactors arranged in rows, wherein the middle 50%-60% of the microfluidic channels are connected in two rows, and the microfluidic channels in the inlet and outlet are connected in a single row. Furthermore, the ratio of the number of microfluidic channel rows in the inlet to the number of microfluidic channel rows in the outlet is 1:2-3.

[0088] (b) The microfluidic channels are sheet-like microreactors arranged in rows, with each microfluidic channel connected in units of two rows;

[0089] (c) The microfluidic channels are arranged in rows of sheet-like microreactors, wherein the inlet microfluidic channels are connected in pairs, and the rest are connected in single rows.

[0090] In this context, the arrangement of sheet-like microreactors within a microreactor, with multiple repetitions defined by (a) and (b) plus (c) as units, refers to a sheet-like microreactor defined by (a) and multiple repetitions defined by (b) + (c). Each repetition defined by (b) plus (c) is a repetition of (b) and (c) as a unit. For example, if a microreactor comprises 13-15 sheet-like microreactors, when the microreactor comprises 13 sheet-like microreactors, the sheet-like microreactors within the microreactor are arranged sequentially with one (a) and six sheet-like microreactors defined by (b) and (c); when the microreactor comprises 15 sheet-like microreactors, the sheet-like microreactors within the microreactor are arranged sequentially with one (a) and seven sheet-like microreactors defined by (b) and (c).

[0091] Preferably, the microreactor comprises 13-15 sheet-like microreactors, wherein the number of sheet-like microreactors is odd.

[0092] The reactant inlet and product outlet of the microreactor are located at opposite ends of the microfluidic channel. In some embodiments, the reactant inlet and product outlet of the microreactor are located on opposite sides of the microreactor, or at the furthest edges of adjacent sides.

[0093] Furthermore, in this invention, the microreactor and the heat exchanger are spaced apart to better control the temperature of the microreactor. In some embodiments, the cross-section of the microfluidic channels in the microreactor is rhomboid, circular, or near-circular (the ratio of the major to minor axis is no greater than 1.2), as described above, and will not be repeated here.

[0094] If the microfluidic channels of the sheet-like microreactor are hollowed out or largely hollowed out, the two sides of the sheet-like microreactor bulge outwards. Correspondingly, the heat exchanger is shaped to fit the microreactor, allowing them to adhere closely and cover the sides of the sheet-like microreactor, achieving a larger contact area and faster heat dissipation. In some embodiments, the heat exchanger consists of rows of parallel pipes connected end-to-end, with pipe diameters ranging from 0.5 to 1.5 cm. For example, in some embodiments, the pipe diameters are 0.5 cm, 0.8 cm, 1.0 cm, 1.2 cm, 1.5 cm, etc. Flow-encircling columns are also uniformly arranged within the pipes of the heat exchanger. The distance between the rows of parallel pipes is 1 / 4 to 1 / 8 of the pipe diameter.

[0095] In different implementations, the microreactor may include 13, 14, or 15 plate-shaped microreactors; in different implementations, the heat exchanger may include 15, 16, or 17 plate-shaped heat exchangers.

[0096] The plate-shaped microreactors and plate-shaped heat exchangers are stacked together, with the plate-shaped microreactors located between the plate-shaped heat exchangers. In this way, plate-shaped heat exchangers are set on both sides of the plate-shaped microreactors, which facilitates the timely dissipation of heat from the plate-shaped microreactors.

[0097] Multiple sheet-like microreactors are connected in series via microfluidic channels within them. The heat exchange channels of the sheet-like heat exchanger may or may not be connected. Even with multiple sheet-like microreactors, the reactant inlet and product outlet of each microreactor are located at the beginning and end of all the series-connected microfluidic channels, respectively. In some embodiments, the microreactor comprises multiple sheet-like microreactors, with the reactant inlet and product outlet located on the first and last stacked sheet-like microreactors, respectively.

[0098] In some embodiments, the microreactor includes a primary reaction zone and a secondary reaction zone connected in sequence, wherein the primary reaction zone has a liquid load of 90%-110% of that of the secondary reaction zone.

[0099] The microreactor consists of a primary reaction zone and a secondary reaction zone connected in series. Since the sheet-like microreactors are similar, approximately half of the sheet-like microreactors connected in series constitute the primary reaction zone, and the remainder constitute the secondary reaction zone.

[0100] For example, if a microreactor consists of 13 sheet-like microreactors, then the first 6 or 7 sheet-like microreactors are the primary reaction zone, and the rest are the secondary reaction zone.

[0101] For example, if a microreactor consists of 14 sheet-like microreactors, then the first 7 or the first 7 sheet-like microreactors are the primary reaction zone, and the rest are the secondary reaction zone.

[0102] For example, if a microreactor consists of 15 sheet-like microreactors, then the first 7 or 8 sheet-like microreactors are the primary reaction zone, and the rest are the secondary reaction zone.

[0103] In this invention, the 13-15 sheet-like microreactors are the same or similar in size, thickness, material, pore size of the microfluidic channels, and liquid loading capacity of the microfluidic channels.

[0104] Therefore, for multiple sheet-like microreactors connected in series, they are divided into two reaction zones. In the primary reaction zone, the sheet-like microreactors are arranged as follows: In the first sheet-like microreactor, rows 1-3 from the reactant inlet are connected in a single row, the middle section is connected in two-row units, and rows 2-5 at the outlet are connected in a single row. The second, third, and subsequent sheet-like microreactors, up to the sixth, seventh, or eighth sheet-like microreactor, are sequentially connected with each other. Sheet-like microreactors are arranged with a main connection in two-row units (no less than 75% of the microfluidic channels are connected in two-row units, e.g., all microfluidic channels are connected in two-row units) and sheet-like microreactors are arranged alternately with a main connection in one-row units (no more than 10% of the microfluidic channels are connected in one-row units, e.g., only one set of microfluidic channels is connected in two-row units). Optionally, the second sheet-like microreactor... In the sixth and seventh sheet-like microreactors, the microfluidic channels in adjacent sheet-like microreactors are arranged vertically. That is, in one adjacent sheet-like microreactor, the microfluidic channels are arranged in parallel or substantially parallel rows, while in another sheet-like microreactor, the microfluidic channels are arranged in parallel or substantially parallel columns. Furthermore, sheet-like microreactors primarily connected in two rows are arranged in parallel or substantially parallel rows, while those primarily connected in one column are arranged in parallel or substantially parallel columns. The final sheet-like microreactor is equipped with a product outlet.

[0105] The sheet-like microreactors in the secondary reaction zone are set up in the same manner as those in the primary reaction zone.

[0106] Optionally, each reaction zone is equipped with at least one of the aforementioned temperature controllers to control the temperature of each reaction zone. Similarly, the temperature controllers may be equipped with multiple sensors to detect the temperature of different sheet-like microreactors or different parts of the sheet-like microreactors, thereby controlling the temperature in different reaction zones.

[0107] Optionally, the temperature of the primary reaction zone is controlled at 60-80℃, and the temperature of the secondary reaction zone is controlled at 80-100℃. In different embodiments, the temperature of the primary reaction zone can be controlled at 60℃, 70℃, 75℃, and 80℃, etc. Similarly, in different embodiments, the temperature of the secondary reaction zone can be controlled at 80℃, 85℃, 90℃, 95℃, and 100℃, etc.

[0108] Furthermore, in this invention, the heat exchanger is provided with heat exchange channels, the aperture of which is 0.5-1.5 cm. The heat exchange channels in the heat exchanger are arranged in parallel columns, with adjacent columns connected. For example, starting from the first column at the inlet, the end of the first column connects to the closest end of the second column, and then the other end of the second column connects to the closest end of the third column; and so on. If all the heat exchange channels in the heat exchanger are connected in series, then the starting end of all heat exchange channels is the cooling medium inlet, and the ending end is the cooling medium outlet. In some embodiments, the inlet and outlet of the heat exchanger are located on opposite sides of the heat exchanger body, or at the furthest edges of adjacent sides. If multiple heat exchangers are connected in series, for stacked heat exchangers, the cooling medium inlet is usually located on the first heat exchanger, while the cooling medium outlet is usually located on the last heat exchanger.

[0109] In this invention, the heat exchange channels in the heat exchanger are sealed pipes, meaning that the heat exchange channels are interconnected but sealed relative to the outside. The cross-section of the heat exchange channels is circular or approximately circular. The heat exchange channels can be arranged in a flat plate or be hollowed out. Each column of heat exchange channels is provided with multiple flow-around columns, or the flow-around columns are evenly distributed in each row of heat exchange channels.

[0110] In some implementations, the distance between each heat exchange channel is no more than 1.5 times and no less than 0.5 times the cross-section of the heat exchange channel, such as 0.5 times, 0.8 times, 1 time, 1.2 times, 1.5 times, etc.

[0111] To achieve cooling more quickly and stably, optionally, there are two plate heat exchangers between the last plate microreactor in the primary reaction zone and the first plate microreactor in the secondary reaction zone.

[0112] Optionally, the microfluidic channels within the microreactor are made of silicon carbide. The silicon carbide microfluidic channels are less susceptible to corrosion, enhancing the equipment's sustainable utilization and reducing maintenance costs.

[0113] Furthermore, the microfluidic reaction device also includes a cover plate located on the surface of the microreactor.

[0114] Furthermore, the microfluidic reactor further includes at least one of the following:

[0115] A premixing unit is connected to the inlet of the microreactor and is used to mix the raw materials entering the microreactor.

[0116] A reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the premixing unit or the inlet of the microreactor;

[0117] An extraction unit is connected to the microreactor.

[0118] In some embodiments, the microfluidic reactor further includes a premixing unit connected to the inlet of the microreactor, the premixing unit being used to premix the raw materials entering the microreactor;

[0119] and / or a reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the premixing unit or the inlet of the microreactor.

[0120] In some embodiments, the microfluidic reactor further includes a premixing unit connected to the inlet of the microreactor. The premixing unit is used to mix the raw materials entering the microreactor. The mixing method and apparatus of the premixing unit are not particularly limited, as long as they achieve a certain mixing effect; the specific structure is not particularly limited. For example, the premixing unit can be set up separately or on a cover plate. The premixing unit is used to input different reactants and to mix them. The premixing unit can be a pipe or a container, and mixing can be achieved by inverting or rotating the container itself, or by an external stirrer. After the different reactants are mixed by the premixing unit, they are then fed into the microreactor through the reactant inlet.

[0121] In some embodiments, the microfluidic reactor further includes a reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the inlet of the microreactor. In some embodiments, the reflux unit is a pipeline capable of controlling the flow rate, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the inlet of the microreactor, with the flow rate of the liquid in the pipeline controlled by a flow rate control device on the pipeline.

[0122] In some embodiments, the microfluidic reactor further includes a premixing unit connected to the inlet of the microreactor, the premixing unit being used to mix the raw materials entering the microreactor;

[0123] A reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the premixing unit.

[0124] In some embodiments, the microfluidic reactor further includes an extraction unit connected to the outlet of the microreactor.

[0125] The extraction unit is used to further process the product exiting the microreactor to achieve purification. The extraction unit may include crude extraction and fine extraction, both of which generally employ a batch reactor.

[0126] The method for preparing alkyl sulfonic acid using the microfluidic reaction device described above, provided by the present invention, has at least the following beneficial effects: high reaction efficiency, short production cycle, low impurity content in the obtained product, high product yield, and easy mass production.

[0127] The alkyl sulfonic acids in this invention include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, pentan-1-sulfonic acid, hexanesulfonic acid, heptanesulfonic acid, octanesulfonic acid, nonanesulfonic acid, decanesulfonic acid, undecanesulfonic acid, dodecanesulfonic acid, etc.

[0128] Further, the alkyl disulfide comprises methanethiol and R-S2-R, wherein R is C1-C. 12 The alkyl group; the oxidant solution includes an aqueous hydrogen peroxide solution; the self-catalyst solution includes an alkyl sulfonic acid solution.

[0129] Furthermore, the alkyl disulfide includes dimethyl disulfide, diethyl disulfide, or methanethiol.

[0130] Preferably, the hydrogen peroxide solution contains 20-35% hydrogen peroxide by mass.

[0131] Preferably, the self-catalyst solution comprises alkyl sulfonic acid as an acidic catalyst, and the mass content of the alkyl sulfonic acid in the self-catalyst solution is 85%-95%.

[0132] Furthermore, the flow rates of the alkyl disulfide solution and the oxidant solution are controlled such that the molar ratio of alkyl disulfide to oxidant in the microfluidic channel is 1:(4-9);

[0133] The flow rate of the self-catalyst solution is controlled so that the mass content of the catalyst in the microfluidic channel is 5%-10%.

[0134] In some embodiments, the mass content of alkyl sulfonic acid in the self-catalyst solution can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, etc. In some embodiments, the mass content of hydrogen peroxide in the hydrogen peroxide solution can be 20%, 25%, 30%, 35%, etc. In some embodiments, the molar ratio of alkyl disulfide to oxidant in the microfluidic channel is 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, etc. In some embodiments, the mass content of catalyst in the microfluidic channel is 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0135] The flow rate of each liquid can be controlled by a metering pump connected to the storage tank, thereby controlling the content of each substance in the reactants. For example, the flow rate of the liquid can be controlled by a metering pump connected to the storage tank, thus controlling the molar ratio of alkyl disulfide to oxidant in the reactants. The flow rate of the catalyst solution can also be controlled by components such as metering pumps to ensure that the mass content of the catalyst in the liquid reactants is 5-10%.

[0136] Optionally, the flow rate of the alkyl disulfide solution is 1.21±0.1 g / s, the flow rate of the oxidant solution is 8.98±0.9 g / s, and the flow rate of the self-catalyst solution is 1.68±0.2 g / s.

[0137] The solvent in the alkyl disulfide solution is water, the solvent in the oxidant solution is also water, and the solvent in the autocatalyst solution is also water.

[0138] In some embodiments, the mixture of the alkyl disulfide solution, the autocatalyst solution, and the oxidant solution passes sequentially through the primary reaction zone and the secondary reaction zone;

[0139] The temperature within the primary reaction zone is controlled to be 60-80℃.

[0140] The temperature within the secondary reaction zone is controlled to be 80-100℃;

[0141] The residence time of the liquid reactants in the microreactor is controlled to be 15-40 s.

[0142] The mixture of the alkyl disulfide solution, the self-catalyst solution, and the oxidant solution passes sequentially through the primary reaction zone and the secondary reaction zone;

[0143] The temperature within the primary reaction zone is controlled to be 60-80℃.

[0144] The temperature within the secondary reaction zone is controlled to be 80-100℃;

[0145] The residence time of the liquid reactants in the microreactor is controlled to be 15-40 s.

[0146] Microfluidic channel reactions can involve sequentially passing liquid reactants through primary and secondary reaction zones. Specifically, the temperature in the primary reaction zone can be controlled at 60-80°C, and the temperature in the secondary reaction zone at 80-100°C. This ensures the reaction proceeds fully, maintains a suitable rate, and guarantees safety. The residence time of the liquid reactants in the microreactor can be controlled to 15-40 seconds by adjusting the flow rate. Specifically, the residence time can be 15s, 18s, 20s, 25s, 30s, 35s, or 40s, etc. This ensures the reaction proceeds fully, achieves a good yield, and prevents excessive heat release from affecting safety performance due to prolonged reaction time.

[0147] In some embodiments, the method further includes:

[0148] The material emanating from the microreactor undergoes a crude extraction process, which includes distillation at a temperature not less than 100°C until the temperature rises to 230°C ± 5°C. The crude extraction process involves distilling the material emanating from the microreactor while slowly raising the temperature from 100°C to 230°C ± 5°C, terminating the distillation to obtain the crudely extracted material. The entire process takes approximately one and a half hours.

[0149] Preferably, the material after the crude extraction is subjected to a refining process, which includes distillation at 180-200°C. The refining and crude extraction processes can be carried out in a single container. After the crude extraction, the pressure in the batch reactor is reduced to 0.8±0.1 MPa, at which point the temperature drops to 180±5°C, and distillation continues until the temperature rises to 200±5°C. At this point, the product obtained consists mainly of alkyl sulfonic acids, except for small amounts of water and acids (such as sulfuric acid).

[0150] The present invention has at least one of the following beneficial effects:

[0151] 1. This invention innovatively uses a microfluidic reaction device to prepare alkyl sulfonic acid, which involves micro-scale reactions, low liquid holdup, low exothermic reaction, easy control of reaction temperature, and high operational safety;

[0152] 2. The reaction channel of the microfluidic reactor of the present invention is formed of silicon carbide, which is not easily corroded, enhances the sustainable utilization rate of the equipment, will not explode, and reduces the equipment maintenance cost.

[0153] 3. The method for preparing alkyl sulfonic acid using a microfluidic reactor in this invention has high reaction efficiency, short production cycle, low impurity content in the obtained product, high product yield, and is easy to mass-produce.

[0154] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0155] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0156] Figure 1 A cross-sectional view of a microreactor according to one embodiment of the present invention is shown;

[0157] Figure 2 A cross-sectional view of a heat exchanger according to one embodiment of the present invention is shown;

[0158] Figure 3 Cross-sectional views of two microreactors according to one embodiment of the present invention are shown;

[0159] Figure 4 A schematic diagram of the structure of a cover plate according to one embodiment of the present invention is shown;

[0160] Figure 5 A schematic diagram of another cover plate according to one embodiment of the present invention is shown;

[0161] Figure 6 A schematic diagram of a microchannel reactor according to an embodiment of the present invention is shown.

[0162] Figure 7 A schematic diagram showing the connections of the components in a microfluidic reactor according to an embodiment of the present invention is provided.

[0163] Explanation of reference numerals in the attached figures:

[0164] 100: Microreactor; 110: Primary reaction zone; 120: Secondary reaction zone; 10: Microfluidic channel; 20: Heat exchanger; 11: Flow-around column; 30A-30F: Mounting holes; 200: Extraction unit; 300: Premixing unit; 400: Alkyl disulfide storage tank; 500: Autocatalyst storage tank; 600: Oxidant storage tank. Detailed Implementation

[0165] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0166] To facilitate understanding, the principle by which this device achieves the aforementioned beneficial effects will be briefly explained below:

[0167] As mentioned earlier, the main method for synthesizing liquid acids is currently batch reactor preparation. However, batch reactor preparation of liquid acids presents certain safety issues: when the reaction temperature is below 80°C, the reaction proceeds slowly, resulting in low yield; however, when the reaction temperature is above 80°C, the reaction becomes more vigorous. To ensure yield, the reactor needs to maintain a certain liquid holdup, thus explosions are prone to occur in closed containers such as reactors. Therefore, to ensure safety, batch reactor preparation of liquid acids has long reaction times and generally low yields. Furthermore, the byproduct of the hydrogen peroxide oxidation method for preparing alkyl sulfonic acids is sulfuric acid, and hydrogen peroxide itself has strong oxidizing properties, thus requiring high acid corrosion resistance in the equipment. This invention uses a microreactor in a microfluidic reactor as the container for the reaction, allowing for thorough mixing and contact of reactants with a relatively small liquid holdup. The reaction occurring within the microfluidic channel is a micro-reaction with low heat release, significantly improving safety. When preparing alkyl sulfonic acids using the hydrogen peroxide oxidation method, all reactants can be liquids, making it suitable for microreactors. Furthermore, the aforementioned micro-reactions can improve the conversion rate of reactants, resulting in products with low impurity content and high yield. Additionally, the microreactor exhibits high reaction efficiency, thus shortening the production cycle.

[0168] The various units and components of the device are further described in detail below according to specific embodiments of the present invention:

[0169] like Figure 7 As shown, the present invention provides a microfluidic reaction device, which includes a microreactor 100. The microreactor 100 includes a primary reaction zone 110 and a secondary reaction zone 120 connected in sequence. Both the primary reaction zone 110 and the secondary reaction zone 120 have microreactors containing microfluidic channels 10 and heat exchangers 20 for maintaining a set temperature in the microreactors. The microfluidic channels 10 (also called reaction channels) of multiple microreactors are connected in series, allowing reactants to flow sequentially through the reaction channels in the primary reaction zone 110 and the secondary reaction zone 120 for sufficient reaction. The reaction occurs from the primary reaction zone 110 towards the secondary reaction zone 120. The reactants are thoroughly mixed in the reaction channels of the microreactor, and the reaction temperature is maintained at a stable level under the action of the heat exchange channels.

[0170] The material supplied to the microreactor 100 may contain a variety of reactants. To ensure sufficient reaction within the microreactor 100, the reactants may be pre-mixed before being supplied to the microreactor 100 (see [link to product description]). Figure 7 (Premixed unit 300).

[0171] Specifically, refer to Figure 7 Before the primary reaction zone 110, there is a cover plate. A premixing unit 300 for introducing different reactants can be installed within the cover plate; that is, the area inside the cover plate serves as a mixing zone. This mixing zone can be in the form of a single pipeline or a container holding a certain volume. The structure of the cover plate is as follows... Figure 4 As shown, where, Figure 4 The circular holes represent through-holes for pipelines of different diameters. For example, pipelines carrying different raw materials can enter the cover plate through different through-holes. The cover plate can be configured to have multiple branch pipes merged into a main pipe (e.g., pipe diameter 5-10mm, length 20-60cm). After mixing through the main pipe, the mixture enters the primary reaction zone 110. This through-hole also includes through-holes for the pipelines of the heat exchanger 20. Similarly, a cover plate can also be installed between the primary reaction zone 110 and the secondary reaction zone 120, with a structure as shown in the diagram. Figure 5 As shown, where, Figure 5 The circular holes are through holes used for connecting different microreactors 100 and for connecting heat exchangers 20.

[0172] For example, the raw material supply area has multiple raw material inlets, including an alkyl disulfide storage tank 400, an autocatalyst storage tank 500, and an oxidant storage tank 600. Each of these tanks can be equipped with a metering pump to control the proportion of materials supplied to the primary reaction zone 110. The reactants are introduced into a mixing zone within a cover plate via different pipelines, and then fed into the primary reaction zone 110. In the primary reaction zone 110, the alkyl disulfide, catalyst, and oxidant are thoroughly mixed and undergo a preliminary reaction before flowing into the secondary reaction zone 120 for further reaction.

[0173] The apparatus further includes an extraction unit 200. The extraction unit 200 is connected to the secondary reaction zone 120 for further purification and extraction of the reaction products. The extraction unit includes a crude extraction process and a fine extraction process. The reactants, mixed in the primary reaction zone 110, react in a microreactor, and the resulting products sequentially pass through the crude and fine extraction processes of the extraction unit 200 to ultimately obtain a high-purity reaction product.

[0174] The product that has been completely reacted in the secondary reaction zone 120 is discharged from the product outlet of the microreactor, and then undergoes crude and fine extraction in the batch reaction of the extraction unit 200 to obtain the finished product.

[0175] The device has at least the following beneficial effects: high reaction efficiency, short production cycle, few product impurities, high product yield, easy mass production, improved operational safety, enhanced equipment sustainability, and reduced equipment maintenance costs.

[0176] Furthermore, the composition and structure of the microfluidic channels in the sheet-like microreactors and the connection relationships between the sheet-like microreactors have been described in detail above, and will not be repeated here.

[0177] Furthermore, the primary reaction zone 110 and the secondary reaction zone 120 each contain a plurality of microreactors 10, which are arranged along a path such as... Figure 6 The AA directions are arranged sequentially as shown. Figure 1 and Figure 3 It shows along Figure 6 A schematic cross-sectional view of the microreactor 10 in the BB direction. Specifically, the primary reaction zone 110 includes sequentially arranged components such as... Figure 1 The microreactor shown, such as Figure 3 The microreactor shown in A, such as Figure 3 The microreactor shown in B, such as Figure 3 The microreactor shown in A, such as Figure 3 The microreactor shown in B, such as Figure 3 The microreactor shown in A and as shown in Figure A Figure 3 The microreactor shown in B, namely the primary reaction zone 110, includes a... Figure 1 The microreactor shown and the three sets as shown Figure 3 The microreactor shown in A and as shown in Figure A Figure 3 The combination of microreactors shown in B. Both sides of the above microreactors are equipped with... Figure 2 The heat exchanger 20 shown is one on each side of each microreactor. Figure 2 It shows along Figure 6 A schematic diagram of the cross-section of heat exchanger 20 in the BB direction. At this point, the specific combination of the microreactor and heat exchanger 20 in the primary reaction zone 110 is as follows: Figure 2 The heat exchanger 20 shown Figure 1 The microreactor shown Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in A Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in B, Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in A Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in B, Figure 2 The heat exchanger 20 shown Figure 3The microreactor shown in A Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in B, Figure 2 The heat exchanger 20 shown, and along Figure 6 Arranged in the AA direction. Additionally, it should be noted that... Figure 1 and Figure 3 The microreactors shown are schematic cross-sectional views. The vertical positions (inlet and outlet) of the microfluidic channels 10 in each microreactor can be adjusted according to actual use; similarly, Figure 2 The heat exchanger 20 shown is also a cross-sectional schematic diagram. The upper and lower positions (inlet and outlet) of the heat exchange channels in each heat exchanger 20 can be adjusted according to their actual use to achieve the purpose of connecting the lower outlet and the lower inlet, and connecting the upper outlet and the upper inlet.

[0178] The microreactors and heat exchangers 20 in the secondary reaction zone 120 are arranged in the same manner as in the primary reaction zone 110.

[0179] The arrangement of the microreactors in the primary reaction zone 110 and the secondary reaction zone 120 is a specific manifestation of the above-mentioned "the sheet-like microreactors in the microreactors are arranged in sequence as one (a) and multiple (b) and (c)".

[0180] The microreactors in the primary reaction zone 110 and the secondary reaction zone 120 have a pore size of 2-5 mm (which can be 2 mm, 3 mm, 4 mm, or 5 mm) and a total liquid loading capacity of 800-1200 mL (which can be 800 mL, 900 mL, 1000 mL, 1100 mL, or 1200 mL).

[0181] in, Figure 1 and Figure 3 The arrangement of microfluidic channels 10 within a microreactor is shown. It can be seen that the microfluidic channels 10 vary slightly between different microreactors; some have more single-row or single-column connections, while others have more double-row connections. The inclusion of flow-around columns 11 within the microfluidic channels 10 also facilitates thorough mixing and reaction of the reactants within the channels 10 and provides the heat exchanger 20 with more heat exchange time. Furthermore, the alternating arrangement of microreactors with rows and columns of microfluidic channels 10 enhances the contact between the reactants themselves, resulting in a more complete reaction within the microfluidic channels 10. Different microreactors include mounting holes 30A-30B, 30C-30D, and 30E-30F.

[0182] The heat exchanger 20 includes a cooling medium inlet, a cooling medium outlet, and flow-around columns 11 distributed throughout the entire heat exchange channel. The cooling medium flows in through the cooling medium inlet and out through the cooling medium outlet, then flows in through the cooling medium inlet of another heat exchange channel and out through the cooling medium outlet, exchanging heat with adjacent microreactors and controlling the reaction temperature. Furthermore, the structure of the heat exchanger 20 is matched to the structure of the microreactor; for example, the protruding parts of the microreactor correspond to the concave parts of the heat exchanger 20, achieving full contact between the two for better heat dissipation and timely temperature control. The cooling medium can be water. The heat exchanger 20 is connected to one or more temperature controllers (not shown in the figure).

[0183] When the reactant stream flows through the primary reaction zone 110, it represents the initial stage of the reaction, during which a significant amount of heat is released. The heat exchanger 20 itself has a relatively low temperature, allowing for more efficient heat exchange to control the reaction temperature at 60-80℃. When the reactant stream flows through the secondary reaction zone 120, it represents the middle and later stages of the reaction. Although less heat is released at this stage, a higher temperature is required, ideally controlled at 80-100℃. Since the heat exchanger 20 itself has a certain temperature, the temperature in the secondary reaction zone 120 is more easily achieved at this level.

[0184] In this invention, the microfluidic channels 10 within the microreactor can be formed from silicon carbide, which is not easily corroded.

[0185] The premixing unit, primary reaction zone 110, and secondary reaction zone 120 occupy an area of ​​8±1m². 3 .

[0186] In addition, this device can be used for the preparation of alkyl sulfonic acids, and can also be used to prepare other compounds whose reaction temperature is difficult to control, have a large amount of reaction byproducts and are corrosive. For example, when a strong acid is required to participate in the reaction and the reaction generates too much heat, the microreactor in this invention can be used for the reaction.

[0187] This invention also provides a method for preparing alkyl sulfonic acid using the aforementioned microfluidic reactor. The method includes supplying an alkyl disulfide solution, a self-catalyst solution, and an oxidant solution to a microreactor for a microfluidic reaction to obtain alkyl sulfonic acid. This method has at least the following advantages: high reaction efficiency, short production cycle, low impurity content in the obtained product, high product yield, and ease of mass production.

[0188] According to embodiments of the present invention, the alkyl disulfide comprises methanethiol and R-S2-R, wherein R is a C1-C12 alkyl group, specifically including dimethyl disulfide, diethyl disulfide, or methanethiol; the oxidant solution comprises an aqueous hydrogen peroxide solution, specifically including 20%-35% hydrogen peroxide; the self-catalyst solution comprises an acidic solution and an acidic catalyst, specifically including 85%-95% benzenesulfonic acid liquid acid and sulfuric acid for catalysis.

[0189] Microfluidic reactions can include the operation of sequentially passing liquid reactants through a primary reaction zone 110 and a secondary reaction zone 120. Specifically, the temperature in the primary reaction zone 110 can be controlled at 60-80°C, and the temperature in the secondary reaction zone 120 can be controlled at 80-100°C. This allows the reaction to proceed fully, ensuring a suitable reaction rate while also guaranteeing reaction safety. By controlling the flow rate of the liquid reactants, the residence time of the liquid reactants in the microreactor can be kept between 15-40 seconds. This allows the reaction to proceed fully, achieving a better yield, and preventing excessive reaction time and exothermic reactions that could compromise safety.

[0190] According to embodiments of the present invention, the flow rates of the alkyl disulfide solution and the oxidant solution can be controlled to ensure that the molar ratio of alkyl disulfide to oxidant in the liquid reactants is 1:(4-9) before entering the microreactor. For example, the liquid flow rate can be controlled by a metering pump connected to a storage tank, thereby controlling the molar ratio of alkyl disulfide to oxidant in the reactants. The flow rate of the catalyst solution can also be controlled by components such as a metering pump to ensure that the mass content of the catalyst in the liquid reactants is 5%-10%.

[0191] According to an embodiment of the present invention, the method further includes a crude extraction process on the material subjected to the microfluidic reaction. The crude extraction process includes, but is not limited to, distillation at 100-230°C. After the crude extraction, a crude product with a purity of approximately 90% is obtained. The material after the crude extraction is then subjected to a refining process, which includes, but is not limited to, distillation at 180-200°C, ultimately yielding a final product with a mass content of approximately 99%.

[0192] In summary, the microfluidic reactor and method for preparing alkyl sulfonic acids proposed in this invention premixes the alkyl disulfide solution, autocatalyst solution, and oxidant solution in a premixing unit before introducing them into the microfluidic reactor for thorough mixing and reaction. The temperature within the reaction channel is controlled by the heat exchange channel, improving operational safety. Furthermore, conducting the reaction in multiple series-connected reaction channels increases reaction efficiency and product yield, facilitating large-scale production. This results in improved reaction efficiency, higher product yield, enhanced operational safety, increased equipment sustainability, and reduced equipment maintenance costs.

[0193] Unless otherwise specified, the methods used in the following examples are conventional methods, and the reagents used are commercially available reagents.

[0194] Example 1

[0195] like Figure 7 As shown, this embodiment provides a microfluidic reaction device, which includes a raw material supply area, a premixing unit, a primary reaction zone 110, a secondary reaction zone 120, and an extraction unit 200 arranged sequentially.

[0196] The raw material supply area includes an alkyl disulfide storage tank 400, an autocatalyst storage tank 500, and an oxidant storage tank 600, all of which are equipped with metering pumps.

[0197] Different raw materials are transported through different pipes to deliver the reactants through the through holes in the cover plate. Figure 4 The mixture is introduced into the premixing unit inside the cover plate. The premixing unit is a pipeline consisting of multiple branch pipes that converge into a main pipe. The main pipe is then introduced into the microreactor 10 in the primary reaction zone 110. Figure 4 The through holes on the cover plate are also used as passageways for heat exchanger 20.

[0198] Both the primary reaction zone 110 and the secondary reaction zone 120 have a lateral flow path. Figure 6 Multiple microreactors, each containing a microfluidic channel 10, are arranged sequentially along the AA direction, along with heat exchangers 20 located on both sides of the microreactors to maintain a set temperature. The microfluidic channels have an aperture of 2-5 mm and a total liquid capacity of 800-1200 mL. Figure 1 and Figure 3 It shows along Figure 6 Schematic diagram of the cross-section of microreactor 10 in the BB direction. Figure 2 It shows along Figure 6 A schematic cross-sectional view of the heat exchanger 20 in the BB direction. Specifically, the primary reaction zone 110 includes [the following section is missing from the original text] along [the following section is missing from the original text] Figure 6 The microreactors 10 and heat exchangers 20 are arranged sequentially along the AA direction, as follows: Figure 2 The heat exchanger 20 shown Figure 1 The microreactor shown Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in A Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in B, Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in A Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in B, Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in A Figure 2 The heat exchanger 20 shown Figure 3 The microreactor shown in B, Figure 2 The heat exchanger 20 shown.

[0199] It should be noted that, Figure 1 and Figure 3 The microreactors shown are schematic cross-sectional views. The vertical positions (inlet and outlet) of the microfluidic channels 10 in each microreactor can be adjusted according to actual use; similarly, Figure 2 The heat exchanger 20 shown is also a cross-sectional schematic diagram. The upper and lower positions (inlet and outlet) of the heat exchange channels in each heat exchanger 20 can be adjusted according to their actual use to achieve the purpose of connecting the lower outlet and the lower inlet, and connecting the upper outlet and the upper inlet.

[0200] The microreactors and heat exchangers 20 in the secondary reaction zone 120 are arranged in the same manner as in the primary reaction zone 110.

[0201] In addition, a space is provided between the primary reaction zone 110 and the secondary reaction zone 120, such as Figure 5 The cover plate shown, Figure 5 The circular holes are through holes used for connecting different microreactors 100 and for connecting heat exchangers 20.

[0202] The premixing unit, primary reaction zone 110, and secondary reaction zone 120 occupy an area of ​​8±1m². 3 .

[0203] The product of the secondary reaction is fed into the extraction unit 200 (reactor) for a batch reaction, and the finished product is obtained after crude extraction and fine extraction.

[0204] Example 2

[0205] Alkyl sulfonic acid-methanesulfonic acid was prepared using a microfluidic reaction apparatus as described in Example 1.

[0206] Dimethyl disulfide is fed into the premixing unit at a flow rate of 1.21 g / s. The catalyst is a solution containing 90% methanesulfonic acid (mass percentage, which can be derived from the crude product) and a small amount of sulfuric acid (mass percentage less than 0.1%) (solvent is water). The catalyst feed rate ensures that the amount of catalyst (methanesulfonic acid) in the reactants is 5% (mass percentage). The catalyst is fed into the premixing unit at a flow rate of 1.68 g / s. The oxidant is a 30% hydrogen peroxide solution, fed into the premixing unit at a flow rate of 8.98 g / s. The premixing unit is kept at room temperature. After mixing, the solution sequentially enters the primary reaction zone and the secondary reaction zone. The temperature of the primary reaction zone is controlled at 80℃, and the temperature of the secondary reaction zone is controlled at 90℃. The total liquid holdup of the microreactor is 1000 mL, the residence time is 15 s, and the entire production system occupies an area of ​​8 m².2 The product collected from the secondary reaction zone was crudely extracted by distillation in a four-necked flask, with the flask temperature raised to 230°C to obtain a crude product. The crude product was then subjected to distillation at reduced pressure to 0.8 MPa for further purification, with the flask temperature raised from 180°C to 200°C to complete the purification and obtain the final methanesulfonic acid product.

[0207] Monitoring and analysis of the product liquid obtained from the last microreactor in the secondary reaction zone revealed that the product contained less than 0.01% dimethyl disulfide, less than 0.05% sulfate, 40% methanesulfonic acid (by mass), and the remainder was water. The crude product contained 90% methanesulfonic acid (by mass), while the refined product contained 99% methanesulfonic acid (by mass), with the remainder being water. Impurity testing of the methanesulfonic acid product showed that the impurity content was below 10 ppm.

[0208] Two repeated experiments were conducted according to this embodiment. The selectivity of methanesulfonic acid in the refined product was 99.85% and 99.72%, respectively. The conversion rate of dimethyl disulfide in the liquid product obtained from the last microreactor in the secondary reaction zone was over 99.9% in both cases. The yield of the liquid acid, methanesulfonic acid, in this reaction was over 99%.

[0209] Example 3

[0210] Methylsulfonic acid was prepared using a microfluidic reactor as described in Example 1. Methylsulfonic acid was prepared according to the method of Example 2, except that: the catalyst feed rate ensured that the catalyst content in the reactants was 9% (mass percentage); after mixing, the feed solution sequentially entered the primary reaction zone and the secondary reaction zone, with the temperature of the primary reaction zone controlled at 80°C and the temperature of the secondary reaction zone controlled at 85°C.

[0211] Monitoring and analysis of the product liquid obtained from the last microreactor in the secondary reaction zone revealed that the product contained less than 0.01% dimethyl disulfide, less than 0.05% sulfate, 40% methanesulfonic acid (by mass), and the remainder was water. The crude product contained 90% methanesulfonic acid (by mass), while the refined product contained 99% methanesulfonic acid (by mass), with the remainder being water. Impurity testing of the methanesulfonic acid product showed that the impurity content was below 10 ppm.

[0212] Three repeated experiments were conducted according to this embodiment. The selectivity of methanesulfonic acid in the refined product was over 99.9%; the conversion rate of dimethyl disulfide in the liquid product obtained from the last microreactor in the secondary reaction zone was over 99.9% in all three cases. The yield of the liquid acid, methanesulfonic acid, in this reaction was over 99%.

[0213] Example 4

[0214] Propanesulfonic acid was prepared using the microfluidic reactor described in Example 1, following the method in Example 2. The specific preparation steps differed from Example 2 only in the following ways: dipropyl disulfide was used as the alkyl disulfide; the catalyst was a solution of 90% (mass percentage, which can be derived from the crude product) propanesulfonic acid and a small amount of sulfuric acid (mass percentage less than 0.1%) (solvent was water); and the catalyst feed rate ensured that the amount of catalyst (propanesulfonic acid) in the reactants was 8% (mass percentage). Propanesulfonic acid was finally obtained.

[0215] Monitoring and analysis of the product liquid obtained from the last microreactor in the secondary reaction zone revealed that the product contained less than 0.01% dipropyl disulfide, less than 0.05% sulfate, and approximately 40% (by mass) propanesulfonic acid, with the remainder being water. The crude product contained approximately 90% (by mass) propanesulfonic acid, while the refined product contained approximately 99% (by mass) propanesulfonic acid, with the remainder being water. Impurity testing of the propanesulfonic acid product showed that the impurity content was below 10 ppm.

[0216] Multiple repeated experiments were conducted according to this embodiment, and the selectivity of propanesulfonic acid in the refined product was consistently above 99%. The conversion rate of dipropyl disulfide in the liquid product obtained from the last microreactor in the secondary reaction zone was consistently above 99.9%. The yield of the liquid acid, propanesulfonic acid, in this reaction was consistently ~99%.

[0217] Example 5

[0218] Octylsulfonic acid was prepared using the microfluidic reactor described in Example 1, following the method in Example 2. The specific preparation steps differed from Example 2 only in the following ways: dioctyl disulfide was used as the alkyl disulfide; the catalyst was a solution of 90% (mass percentage, which could be derived from the crude product) octylsulfonic acid and a small amount of sulfuric acid (mass percentage less than 0.1%) as the catalyst (solvent was water); and the catalyst feed rate ensured that the amount of catalyst (octylsulfonic acid) in the reactants was 7% (mass percentage). Octylsulfonic acid was finally obtained.

[0219] Monitoring and analysis of the product liquid obtained from the last microreactor in the secondary reaction zone revealed that the product contained less than 0.01% dioctyl disulfide, less than 0.05% sulfate, 40% octyl sulfonic acid (mass percentage), and the remainder was water. The crude product contained 90% octyl sulfonic acid (mass percentage), while the refined product contained 99% octyl sulfonic acid (mass percentage), with the remainder being water. Impurity testing of the octyl sulfonic acid product showed that the impurity content was below 10 ppm.

[0220] Multiple repeated experiments were conducted according to this embodiment. The selectivity of octylsulfonic acid in the refined product was over 99%. The conversion rate of dioctyl disulfide in the liquid product obtained from the last microreactor in the secondary reaction zone was over 99.9%. The yield of the liquid acid, octylsulfonic acid, in this reaction was consistently around 99%.

[0221] The above method can also be used to prepare ethanesulfonic acid, butyric acid, pentasulfonic acid, hexanesulfonic acid, heptanesulfonic acid, nonansulfonic acid, decanesulfonic acid, undecylsulfonic acid, dodecylsulfonic acid, etc., with yields of ~99%.

[0222] In the above embodiments, the alkyl sulfonic acid was detected by acid-base neutralization titration, as follows:

[0223] 1. Reagents and solutions

[0224] a) 0.5 mol / L NaOH standard solution: prepared and standardized according to GB / T 601.

[0225] b) 1% phenolphthalein indicator solution (color change range 8.0-9.6): Prepared according to GB / T 603.

[0226] 2. Instruments

[0227] Electronic balance: graduation value 0.1mg.

[0228] 3. Experimental Procedure

[0229] Weigh 1.5g of sample and transfer it to a 250mL Erlenmeyer flask with about 80mL of pure water. Add 2 drops of phenolphthalein indicator and titrate with 0.5mol / L NaOH standard solution until the endpoint is pink.

[0230] Reaction equation: CH3-SO3H + NaOH = CH3-SO3Na + H2O

[0231] 4. Calculation formula

[0232] The percentage content of the target compound (alkyl sulfonic acid) is calculated using the following formula:

[0233] X = (96.12 * C1 * V1 / M1 * 1000) * 100

[0234] Among them, X - the percentage content of the target analyte, %;

[0235] The molar concentration of the C1-NaOH standard solution, in mol / L;

[0236] V1 - Volume of NaOH standard solution consumed in the titration, mL;

[0237] M1 - Sample mass, g.

[0238] Selectivity = mass of alkyl sulfonic acid measured in the product / mass of alkyl sulfonic acid theoretically generated from dimethyl disulfide. The mass of alkyl sulfonic acid measured in the product is determined by the above-mentioned alkaline titration.

[0239] Conversion rate = 100% - mass percentage of dimethyl disulfide in the product.

[0240] Yield = Conversion rate * Selectivity.

[0241] In the above embodiments, "~" refers to a range within ±1% of the value.

[0242] Therefore, the apparatus and method proposed in this invention for producing alkyl sulfonic acid, by conducting the reaction in a microchannel, allows for a micro-scale reaction that can withstand the heat released during the reaction without exploding, greatly improving operational safety. The product also exhibits low impurity content and high yield. The microchannels are made of silicon carbide, which is resistant to corrosion, enhancing equipment sustainability and reducing maintenance costs. The synthesis process in the microchannel reactor is completed within tens of seconds, resulting in a short production cycle, high efficiency, large output, and ease of mass production.

[0243] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0244] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A microfluidic reaction device, characterized in that, Includes a microreactor and a heat exchanger for maintaining a set temperature in the microreactor; The microreactor is provided with microfluidic channels, and the pore size of the microfluidic channels is 2-5 mm; The microfluidic channel has a reactant inlet and a product outlet; The liquid loading capacity of the microfluidic channel in the microreactor is 800-1200 mL.

2. The microfluidic reaction device according to claim 1, characterized in that, The microfluidic reactor also includes a temperature controller, which controls the cooling medium rate in the heat exchanger by monitoring the temperature of the microreactor, thereby achieving the purpose of controlling the temperature of the microreactor. Optionally, the microfluidic channels are arranged in rows or columns in the microreactor; Optionally, except for the connected portions between rows or columns, the microfluidic channels are configured as diamond-shaped microfluidic channels; Furthermore, the rhomboid arrangement is configured such that the rhomboids meet at angles not exceeding 90°; Optionally, a flow-around column is provided in the middle part of each of the diamond-shaped microfluidic channels; Optionally, the shape of the flow-encircling column is rhomboid, and the side length of the rhomboid of the flow-encircling column is 1 / 3 to 2 / 3 of the side length of the rhomboid microfluidic channel; Furthermore, the diamond-shaped microfluidic channels in adjacent rows or columns are interlocked; Furthermore, the distance between opposite sides of the microfluidic channels in adjacent rows or columns is 20%-60% of the distance between opposite sides of the rhombus.

3. The microfluidic reaction device according to claim 2, characterized in that, The microreactor comprises 13-15 plate-shaped microreactors, and the heat exchanger comprises 15-17 plate-shaped heat exchangers, with the plate-shaped microreactors disposed between the plate-shaped heat exchangers; The microfluidic channels in the sheet-like microreactors are interconnected, and the microfluidic channels between adjacent sheet-like microreactors are interconnected. The heat exchange channels of the plate heat exchanger may or may not be connected; Preferably, in the microreactor, at least 80% of the microfluidic channels are arranged vertically; Furthermore, the sheet-like microreactors in the microreactor are arranged in sequence as a unit of one sheet-like microreactor as defined in (a) and multiple repeats of sheet-like microreactors as defined in (b) plus sheet-like microreactors as defined in (c): (a) The microfluidic channels are sheet-like microreactors arranged in rows, wherein the middle 50%-60% of the microfluidic channels are connected in two rows, and the microfluidic channels in the inlet and outlet are connected in a single row. Furthermore, the ratio of the number of microfluidic channel rows in the inlet to the number of microfluidic channel rows in the outlet is 1:2-3. (b) The microfluidic channels are sheet-like microreactors arranged in rows, with each microfluidic channel connected in units of two rows; (c) The microfluidic channels are arranged in rows of sheet-like microreactors, wherein the inlet microfluidic channels are connected in pairs, and the rest are connected in single rows.

4. The microfluidic reaction device according to claim 3, characterized in that, The microreactor includes a primary reaction zone and a secondary reaction zone connected in sequence, wherein the liquid loading of the primary reaction zone is 90%-110% of that of the secondary reaction zone. Optionally, each reaction zone is provided with at least one of the aforementioned temperature controllers; Optionally, the temperature of the primary reaction zone is controlled at 60-80℃, and the temperature of the secondary reaction zone is controlled at 80-100℃.

5. The microfluidic reaction device according to claim 4, characterized in that, There are two plate-shaped heat exchangers between the last plate-shaped microreactor in the primary reaction zone and the first plate-shaped microreactor in the secondary reaction zone; Optionally, the microfluidic channels within the microreactor are made of silicon carbide.

6. The microfluidic reactor according to any one of claims 1-5, characterized in that, The microfluidic reactor further includes at least one of the following: A premixing unit, which is connected to the inlet of the microreactor; A reflux unit, one end of which is connected to the outlet of the microreactor, and the other end of which is connected to the premixing unit or the inlet of the microreactor; An extraction unit is connected to the outlet of the microreactor.

7. A method for preparing alkyl sulfonic acid using the microfluidic reactor according to any one of claims 1-6, characterized in that, include: An alkyl disulfide solution, a self-catalyst solution, and an oxidant solution are supplied to the microfluidic channel in the microreactor to carry out a microfluidic reaction in order to obtain the alkyl sulfonic acid.

8. The method according to claim 7, characterized in that, The alkyl disulfide includes methanethiol and R-S2-R, wherein R is C1-C. 12 alkyl groups; The oxidant solution includes an aqueous hydrogen peroxide solution; The self-catalyst solution includes an alkyl sulfonic acid solution; Optionally, the alkyl disulfide includes dimethyl disulfide, diethyl disulfide, or methanethiol; Optionally, the hydrogen peroxide solution contains 20%-35% hydrogen peroxide by mass. Optionally, the self-catalyst solution includes alkyl sulfonic acid as an acidic catalyst, and the mass content of the alkyl sulfonic acid in the self-catalyst solution is 85%-95%.

9. The method according to claim 8, characterized in that, The flow rates of the alkyl disulfide solution and the oxidant solution are controlled such that the molar ratio of alkyl disulfide to oxidant in the microfluidic channel is 1:(4-9); The flow rate of the self-catalyst solution is controlled so that the mass content of the catalyst in the microfluidic channel is 5%-10%; Optionally, the flow rate of the alkyl disulfide solution is 1.21±0.1 g / s, the flow rate of the oxidant solution is 8.98±0.9 g / s, and the flow rate of the self-catalyst solution is 1.68±0.2 g / s.

10. The method according to any one of claims 7-9, characterized in that, The mixture of the alkyl disulfide solution, the self-catalyst solution, and the oxidant solution passes sequentially through the primary reaction zone and the secondary reaction zone; The temperature within the primary reaction zone is controlled to be 60-80℃. The temperature within the secondary reaction zone is controlled to be 80-100℃; The residence time of the liquid reactants in the microreactor is controlled to be 15-40 s.

11. The method according to claim 10, characterized in that, Further includes: The material at the outlet of the microreactor is subjected to a crude extraction process, which includes distillation at a temperature of not less than 100°C until the temperature rises to 230±5°C. Preferably, the material that has undergone the crude extraction process is subjected to a fine extraction process, which includes distillation at 180-200°C.

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