Chromatographic column based on composite stationary phase material and method for its production

Abstract

The application discloses a chromatographic column based on a composite stationary phase material and a preparation method thereof. The chromatographic column comprises a micro flow channel, a stand column, a substrate and a cover plate. The micro flow channel is located in the substrate, the stand column is located in the micro flow channel, and the cover plate is located on the surface of the substrate and covers the micro flow channel. A cavity is formed through the cover plate and the micro flow channel. The inner wall of the micro flow channel is coated with a composite stationary phase. The composite stationary phase material has excellent separation performance even for complex gas components. A tapered bend is used at the bend of the extension direction of the micro flow channel, so that the problems of wide peak type and easy tailing existing in the current micro flow channel structure are solved.

Description

Technical Field

[0001] This invention belongs to the field of microelectromechanical systems (MEMS) technology and relates to a chromatographic column based on a composite stationary phase material and its preparation method. Background Technology

[0002] Gas chromatography (GC) separates mixed gases along the time axis by utilizing the differences in the distribution coefficients of each gas component with the stationary phase, enabling high-precision, interference-free detection of complex multi-component gases. However, the core component of traditional chromatographs is the capillary quartz column, which is 15–60 m long and suspended in the column oven by being wound into a ring. The diameter of the winding ring limits the volume of the column oven, becoming the main reason for the large size and high power consumption of traditional chromatographs. Furthermore, traditional chromatographs require dedicated high-purity carrier gas cylinders such as nitrogen and hydrogen for the detector, further increasing the instrument's size and limiting its portability. To meet the needs of on-site monitoring, miniaturization of gas chromatography technology is urgently needed.

[0003] Miniature chromatographic columns are the core component for miniaturizing and porting large gas chromatographs. Most existing columns are less than 5 meters in length, limiting their ability to separate complex gas mixtures. Their resolution is also extremely low, especially when separating gases with similar physicochemical properties, failing to meet the requirements of industrial applications. Ionic liquids and metal-organic frameworks have been used as stationary phase materials, but their separation mechanisms are relatively simple and their separation capabilities are limited. To improve column efficiency per unit length and enhance separation performance, it is necessary to increase the specific surface area of ​​the stationary phase and prepare composite stationary phase materials. Most existing columns employ a serpentine flow path layout, which is prone to diffusion at bends, causing peak broadening and exacerbating peak tailing. These problems severely restrict the development and application of microchromatographic analysis technology.

[0004] To address the aforementioned problems, this invention proposes a chromatographic column based on a composite stationary phase material and its preparation method for on-site detection of complex gas components. Summary of the Invention

[0005] To overcome the aforementioned problems, the inventors conducted intensive research and developed a chromatographic column based on a composite stationary phase material and its preparation method. The chromatographic column includes microchannels, a column, a substrate, and a cover plate. The microchannels are located within the substrate, the column is located within the microchannels, and the cover plate is located on the substrate surface and covers the microchannels, forming a chamber through the cover plate and microchannels. A composite stationary phase is coated on the inner wall of the microchannels. This composite stationary phase material combines the molecular sieving function of a metal-organic framework with the separation function of an ionic liquid stationary phase, achieving two-stage separation and thus improving the separation performance of the chromatographic column for volatile organic compounds, especially improving the separation degree of gases with similar physicochemical properties. The bends in the extension direction of the microchannels are tapered, effectively reducing the half-maximum width (HWHM) and solving the problems of wide peaks and tailing inherent in existing microchannel structures, thus completing this invention.

[0006] Specifically, the object of the present invention is to provide the following aspects:

[0007] Firstly, a composite stationary phase material for chromatographic columns is provided.

[0008] The specific surface area of ​​the composite stationary phase material is between 900 and 1100 m². 2 Between / g;

[0009] The composite stationary phase material includes an ionic liquid stationary phase and a metal-organic framework;

[0010] The composite stationary phase material first uses the metal-organic framework as a molecular sieve to preliminarily classify gases according to the diameter of different gas molecules. Then, the composite stationary phase material separates the molecules of each type of gas using an ionic liquid stationary phase to achieve two-stage separation.

[0011] Secondly, a method for preparing a composite stationary phase material for a chromatographic column is provided, the method comprising:

[0012] Step 1: Prepare the ionic liquid solution;

[0013] Step 2: Add a metal-organic framework to the ionic liquid solution to obtain a mixed solution;

[0014] Step 3: Post-process the mixed solution to obtain the composite stationary phase material.

[0015] Thirdly, the application of the composite stationary phase material according to the first aspect in a chromatographic column is provided.

[0016] Fourthly, a chromatographic column is provided, the chromatographic column comprising:

[0017] Substrate;

[0018] Microchannels, wherein the microchannels are located in the substrate;

[0019] A column, wherein the column is located in the microchannel;

[0020] A cover plate is located on the surface of the substrate and covers the microchannels, forming a chamber through the cover plate and the microchannels;

[0021] A composite stationary phase material is coated on the inner wall of a microchannel.

[0022] Fifth aspect. A method for preparing a chromatographic column is provided, the method comprising:

[0023] Microchannels are etched in the substrate, and pillars are formed in the microchannels;

[0024] A cover plate is bonded to the substrate surface and covers the microchannels, forming a chamber through the cover plate and the microchannels;

[0025] The composite stationary phase material is coated on the inner wall of the microchannel.

[0026] The beneficial effects of this invention include:

[0027] (1) The composite stationary phase material provided by the present invention has excellent separation performance for complex gas components;

[0028] (2) The composite stationary phase material provided by the present invention can combine the molecular sieve function of metal-organic framework and the separation function of ionic liquid stationary phase to play a two-stage separation role, thereby improving the separation performance of chromatographic column for volatile organic compounds, especially improving the separation degree of gases with similar physicochemical properties.

[0029] (3) The chromatographic column provided by the present invention adopts a conical bend at the bend of the microchannel extension direction, which effectively reduces the half peak width and solves the problems of wide peak shape and easy tailing in the existing microchannel structure.

[0030] (4) The chromatographic column provided by the present invention can be used for on-site detection of complex gas components, as well as for separation of environmental gases and human exhaled gases, and has broad application prospects. Attached Figure Description

[0031] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0032] In the attached diagram:

[0033] Figure 1(a) shows a schematic diagram of the structure after forming a photoresist masking layer on the substrate surface according to a preferred embodiment of the present invention;

[0034] Figure 1(b) shows a schematic diagram of the structure after etching the substrate based on a photoresist masking layer according to a preferred embodiment of the present invention;

[0035] Figure 1(c) shows a schematic diagram of the structure after the cover plate is bonded to the surface of the substrate according to a preferred embodiment of the present invention;

[0036] Figure 1(d) shows a schematic diagram of the structure after a photoresist masking layer is formed on the bottom of the substrate according to a preferred embodiment of the present invention;

[0037] Figure 1(e) shows a schematic diagram of the structure after a temperature control unit is provided at the bottom of the substrate according to a preferred embodiment of the present invention;

[0038] Figure 1(f) shows a schematic diagram of the structure after a composite stationary phase material is formed on the inner wall of a microchannel according to a preferred embodiment of the present invention;

[0039] Figure 2 This shows a partial SEM image of a chromatographic column according to a preferred embodiment of the present invention;

[0040] Figure 3 Show Figure 2 Three-dimensional SEM characterization of part B;

[0041] Figure 4 Show Figure 2 Enlarged view of part A;

[0042] Figure 5 The image shows a SEM image of the composite stationary phase material prepared in Example 1;

[0043] Figure 6 The partial SEM image of the chromatographic column prepared in Comparative Example 1 is shown.

[0044] Figure 7 Show Figure 6 Enlarged view of part C;

[0045] Figure 8 A comparison graph showing the separation effect of the chromatographic column prepared in Example 1 on a mixture of alkane gases is shown.

[0046] Figure 9 The diagram shows a comparison of the separation performance of the chromatographic column prepared in Comparative Example 1 for a mixture of alkane gases.

[0047] Explanation of reference numerals in the attached figures

[0048] 1-Substrate;

[0049] 11-Silicon layer;

[0050] 12-Silica layer;

[0051] 2-Photoresist masking layer;

[0052] 3-Columns;

[0053] 4-Microchannels;

[0054] 5-Cover plate;

[0055] 6-Temperature control unit;

[0056] 61-Electrode;

[0057] 62 - Heating wire;

[0058] 7-Composite stationary phase materials. Detailed Implementation

[0059] The following will refer to the appendix. Figures 1(a) to 9 Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0060] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0061] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this invention, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0062] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0063] In a first aspect, the present invention aims to provide a composite stationary phase material for chromatographic columns, wherein the specific surface area of ​​the composite stationary phase material is between 900 and 1100 m². 2 Between / g, the composite stationary phase material includes an ionic liquid stationary phase and a metal-organic framework. The composite stationary phase material first uses the metal-organic framework as a molecular sieve to preliminarily classify gases according to the diameter of different gas molecules. Then, the composite stationary phase material uses the ionic liquid stationary phase to separate the molecules of each type of gas to achieve two-stage separation.

[0064] In this invention, the ionic liquid stationary phase is preferably selected from trihexyl(tetradecyl)phosphinebis(trifluoromethylsulfonyl)amine (chemical formula: C 34 H 68 F6NO4PS2, [P66614][NTf2]), trihexyltetradecylphosphine chloride (chemical formula: C 32 H 68 ClP, [P66614][Cl]), 1-butyl-3-methylimidazolium tetrafluoroboric acid (chemical formula: C8H15N2BF4, [Bmim][BF4]), for example [P66614][NTf2]; the metal-organic framework is preferably selected from zeolite imidazolium ester framework materials, such as ZIF-8 (chemical formula: C8H15N2BF4, [Bmim][BF4]). 12 N4.Zn, ZIF-11 (chemical formula: C 14 H 12 N4.Zn), ZIF-64 (chemical formula: C3H4N2.Zn++), etc., such as ZIF-8.

[0065] Among them, [P66614][NTf2] is used as the stationary phase of ionic liquid, which has good separation performance for both strongly polar and weakly polar substances, while ZIF-8 has high thermal stability and small particle size.

[0066] In this invention, the composite stationary phase material has a high specific surface area, which improves the column efficiency per unit of the chromatographic column. At the same time, the metal-organic framework, such as ZIF-8, can act as a molecular sieve, effectively classifying gases based on the diameter of different gas molecules. Then, the molecules of each type of gas are separated by an ionic liquid stationary phase, such as [P66614][NTf2]. This achieves two-stage separation. That is, the composite stationary phase material can combine the molecular sieve function of the metal-organic framework and the separation function of the ionic liquid stationary phase to achieve two-stage separation, thereby improving the separation performance of the chromatographic column for volatile organic compounds, especially improving the separation degree of gases with similar physicochemical properties.

[0067] In this invention, the composite stationary phase material exhibits excellent separation performance for complex gas components such as alkanes, alcohols, and benzene compounds. In one embodiment, the composite stationary phase material separates alkanes (pentane, hexane, heptane, octane, nonane, decanane, undecane, and dodecane, labeled C5, C6, C7, C8, C9, C10, C11, and C12, respectively). First, the metal-organic framework ZIF-8 is used as a molecular sieve, and the gases are initially classified according to their molecular dynamic diameters. Alkanes are separated into two main categories: gases with larger molecular dynamic diameters (C8, C9, C10, C11, and C12) and gases with smaller molecular dynamic diameters (C5, C6, and C7). Then, the composite stationary phase material uses an ionic liquid stationary phase [P66614][NTf2] to separate the molecules of each gas category, achieving two-stage separation. The separation degree between pentane and hexane reaches 1.67.

[0068] According to the present invention, the composite stationary phase material has a porous structure with a wavelength of 0.2–0.45 nm; the cations and anions in the ionic liquid stationary phase are uniformly distributed within the pores of the metal-organic framework. Taking [P66614][NTf2] and ZIF-8 as examples, the cation [P66614] in the ionic liquid stationary phase... + and anions [NTf2] - They are evenly distributed within the channels of the metal-organic framework ZIF-8.

[0069] In this invention, the size of the metal-organic framework pores is the same as the pore diameter of the composite stationary phase material. In one embodiment, the pore diameter of the porous structure of the composite stationary phase material is 0.345 nm, and the specific surface area is 1062.42 m². 2 / g.

[0070] In one embodiment, the composite stationary phase material is characterized by SEM as follows: Figure 5 As shown.

[0071] According to the present invention, the mass ratio of the ionic liquid stationary phase to the metal-organic framework can achieve two-stage separation and significantly improve separation performance, especially the separation degree of gases with similar physicochemical properties. The mass ratio of the ionic liquid stationary phase to the metal-organic framework is (1-3):1, preferably (1.5-2.5):1, for example 2:1.

[0072] According to the present invention, the composite stationary phase material is prepared by the following method:

[0073] Step 1: Prepare the ionic liquid solution;

[0074] Step 2: Add ZIF-8 to the ionic liquid solution to obtain a mixed solution;

[0075] Step 3: Post-process the mixed solution to obtain the composite stationary phase material.

[0076] Specifically:

[0077] Step 1: Prepare the ionic liquid solution.

[0078] In step 1, the ionic liquid is added to the organic solution to prepare the ionic liquid solution.

[0079] The ionic liquid is preferably selected from any one or more of [P66614][NTf2], [P66614][Cl], and [Bmim][BF4], for example, [P66614][NTf2]; the organic solvent is a polar organic solvent, preferably selected from any one or more of acetone, ethanol, dichloromethane, and isopropanol, and more preferably acetone.

[0080] In this invention, the ionic liquid, such as [P66614][NTf2], has strong stability in polar organic solvents, especially in acetone, where its chemical properties are even more stable.

[0081] In step 1, the ionic liquid only needs to be dispersed in a polar organic solvent. Typically, the mass ratio of the ionic liquid to the polar organic solvent is 1:(4800-7000), preferably 1:(4900-6000), for example 1:5000.

[0082] Preferably, adding an ionic liquid such as [P66614][NTf2] to the organic solution and stirring at room temperature further promotes the miscibility of the ionic liquid [P66614][NTf2] with the organic solution. A relatively low stirring speed is sufficient, specifically 300–700 r / min. -1 The preferred value is 400–600 r·min -1 For example, 500 r·min -1 .

[0083] Step 2: Add a metal-organic framework to the ionic liquid solution to obtain a mixed solution.

[0084] In step 2, the metal-organic framework is preferably selected from any one or more of ZIF-8, ZIF-11, and ZIF-64, such as ZIF-8; the mass ratio of the ionic liquid to the metal-organic framework in the ionic liquid solution is (1-3):1, preferably (1.5-2.5):1, for example, 2:1. The mass ratio of the ionic liquid to the metal-organic framework affects the degree of modification of the metal-organic framework by the ionic liquid. Specifically, the higher the mass ratio of the ionic liquid to the metal-organic framework, the higher the content of the ionic liquid in the pores of the metal-organic framework. Because the volume ratio of vacancy occupied by the ionic liquid in the pores of the metal-organic framework changes, the amount of ionic liquid adsorbed on the surface of the composite stationary phase material and the pore diameter also change accordingly, thus affecting the subsequent separation effect of complex gases. Within the above parameter range, the composite stationary phase material has a good separation effect on complex gases.

[0085] In step 2, a metal-organic framework is added to the ionic liquid solution at the stirring speed of step 1.

[0086] Furthermore, after adding a metal-organic framework to the ionic liquid solution, ultrasonic treatment is performed. The ultrasonic treatment power is 50-150W and the time is 20-60min; preferably, the ultrasonic treatment power is 70-100W and the time is 30-50min; more preferably, the ultrasonic treatment power is 80-90W and the time is 40-45min, for example, the ultrasonic treatment power is 80W and the time is 40min.

[0087] Ultrasonic treatment can uniformly disperse metal-organic frameworks (MOFs) such as ZIF-8 in organic solutions, and can also break up micron-sized aggregates of ZIF-8, preventing agglomeration. Higher ultrasonic power results in higher cavitation intensity, which is beneficial for the dispersion of ZIF-8; however, excessive power can damage the structure of ZIF-8, so an appropriate ultrasonic power must be selected. Shorter ultrasonic times may lead to insufficient dispersion of ZIF-8, failing to form a uniform suspension, while longer ultrasonic times may prevent the dispersed ZIF-8 from maintaining a stable state, making it prone to re-agglomeration. Therefore, an appropriate ultrasonic time must be selected.

[0088] In this invention, the ultrasound can be performed at room temperature, which is typically 0–40°C, for example, 25°C.

[0089] Step 3: Post-process the mixed solution to obtain the composite stationary phase material.

[0090] In step 3, the post-processing includes stirring, drying, and grinding. The stirring is used to fully immerse the ionic liquid molecules in the ionic liquid solution into the metal-organic framework, and the drying is used to remove the organic solvent, resulting in a dried composite stationary phase material.

[0091] The stirring rate is 700–1200 r / min. -1 The preferred value is 750–1100 r·min. -1 More preferably, 800–1000 r·min -1 The stirring time is 10-36 hours, preferably 15-28 hours, and more preferably 17-18 hours.

[0092] According to a preferred embodiment, the stirring includes:

[0093] First stirring: Seal the mixed solution and stir at 30–50°C at a speed of 700–900 r·min. -1 Stir for 6 to 20 hours.

[0094] Secondary stirring: Leave the mixed solution unsealed and stir at 30–50°C at a speed of 950–1100 r·min. -1 Stir for 3 to 10 hours.

[0095] Three stirring steps: Leave the mixed solution uncovered and stir at 51–80°C at a stirring rate of 950–1200 r·min. -1 Stir for 1 to 6 hours.

[0096] Furthermore, the stirring process involves a first stirring, a second stirring, and a third stirring in sequence.

[0097] The first stirring is used to fully immerse the ionic liquid molecules into the metal-organic framework; the second stirring is used to slowly evaporate the organic solvent in the mixed solution at a temperature below the boiling point of the organic solvent to prevent bumping, that is, to remove most of the organic solvent in the mixed solution; the third stirring is used to rapidly evaporate the remaining organic solvent in the mixed solution at a temperature above the boiling point of the organic solvent.

[0098] Increasing the initial stirring temperature improves the transfer rate of ionic liquid molecules into the metal-organic framework (MOF) channels. However, excessively high temperatures may cause organic solvents to evaporate onto the membrane or vessel walls used to seal the mixture, which is detrimental to the reaction. Increasing the initial stirring rate also improves the transfer rate of ionic liquid molecules into the MOF to some extent, but excessively fast rates are not conducive to the stable adhesion of ionic liquid molecules to the inner and outer surfaces of the MOF channels. Extending the initial stirring time allows for more complete penetration of ionic liquid molecules into the MOF channels, until saturation is reached. At this point, continued stirring will not increase the molecular weight of ionic liquid molecules within the MOF channels, so excessively long stirring times are unnecessary. After the initial stirring, the mixture is no longer sealed, allowing the organic solvent in the mixture to evaporate. Since the stirring temperature is below the boiling point of the organic solvent, the evaporation is slow. Appropriately increasing the stirring rate helps to increase the evaporation rate of the organic solvent and reduce the synthesis time of the composite stationary phase material. Afterwards, raising the temperature to 51-80℃ is beneficial for rapidly evaporating the remaining organic solvent at a temperature higher than the boiling point of the organic solvent. Since the amount of solvent is small at this time, bumping will not occur.

[0099] According to the present invention, during a single stirring process, a Parafilm membrane can be used to seal the mixed solution, or other membranes with good sealing effect can also be used.

[0100] In a further preferred embodiment, the stirring includes:

[0101] First stirring: Seal the mixed solution and stir at 35–45°C at a stirring rate of 750–850 r·min. -1 Stir for 9 to 18 hours.

[0102] Secondary stirring: Leave the mixed solution unsealed and stir at 35–45°C at a stirring rate of 980–1050 r·min. -1 Stir for 4 to 6 hours;

[0103] Three stirring steps: Leave the mixed solution uncovered and stir at 55–65°C at a stirring rate of 1000–1100 r·min. -1 Stir for 2 to 4 hours.

[0104] In a further preferred embodiment, the stirring includes:

[0105] First stirring: Seal the mixed solution and stir at 40°C at a stirring rate of 800 r·min. -1 Stir for 10 hours;

[0106] Secondary stirring: Leave the mixed solution unsealed and stir at 40°C at a stirring rate of 1000 r·min. -1 Stir for 5 hours;

[0107] Three stirring steps: Leave the mixed solution unsealed and stir at 60°C at a stirring rate of 1000 r·min. -1 Stir for 2 hours.

[0108] In this invention, any instrument with a stirring function can be used for stirring, such as a magnetic stirrer.

[0109] In this invention, drying is carried out at 90–120°C for 1–5 hours, preferably at 95–110°C for 1.5–4 hours, for example at 100°C for 2 hours. As the drying temperature increases, the drying time will shorten accordingly. However, excessively high temperatures can easily cause side reactions between the metal-organic framework (MOF) such as ZIF-8 and air, leading to changes in the structure of the MOF such as ZIF-8, thereby causing the collapse of the pore structure. Within the above parameter range, the process is reliable.

[0110] According to the present invention, the dried composite stationary phase material is ground to 50-100 μm, preferably to 60-90 μm, for example to 80 μm; the stationary phase material with a smaller particle size can be fully dispersed in the organic solvent such as ethanol required later, which is beneficial to the subsequent coating of the composite stationary phase material.

[0111] Secondly, the present invention aims to provide a method for preparing a composite stationary phase material for a chromatographic column, the method comprising:

[0112] Step 1: Prepare the ionic liquid solution;

[0113] Step 2: Add a metal-organic framework to the ionic liquid solution to obtain a mixed solution;

[0114] Step 3: Post-process the mixed solution to obtain the composite stationary phase material.

[0115] Thirdly, the present invention aims to provide an application of the composite stationary phase material according to the first aspect in a chromatographic column.

[0116] Fourthly, the present invention aims to provide a chromatographic column, the chromatographic column comprising:

[0117] Substrate 1;

[0118] Microchannel 4, wherein the microchannel 4 is located in the substrate 1;

[0119] Column 3, which is located in the microchannel 4;

[0120] A cover plate 5 is located on the surface of the substrate 1 and covers the microchannels 4, forming a chamber through the cover plate 5 and the microchannels 4.

[0121] Temperature control unit 6, the temperature control unit 6 is located at the bottom of substrate 1;

[0122] The composite stationary phase material 7 is coated on the inner wall of the microchannel 4, as shown in Figure 1(f).

[0123] According to the present invention, the substrate 1 includes a silicon substrate, a glass substrate, and / or a ceramic substrate, preferably a silicon substrate. More preferably, the substrate 1 includes a silicon layer 11 and a silicon dioxide layer 12, wherein the silicon layer 11 is located above the silicon dioxide layer 12. The silicon dioxide layer 12 has a small thickness and serves as an isolation layer. The height ratio of the silicon layer 11 to the silicon dioxide layer 12 is (18-30):1, preferably (20-26):1, for example, 24:1. Microchannels 4 are etched in the silicon layer 11 to form pillars 3, and a temperature control unit 6 is disposed below the silicon dioxide layer 12. The silicon layer 11 is easier to etch microchannels 4 and has a lower cost. The silicon dioxide layer 12 serves as an isolation layer to prevent short circuits in the temperature control unit 6.

[0124] According to the present invention, the microchannel 4 has a first port and a second port, both of which are connected to a quartz capillary tube as connection points to the external air path; the column 3 is located in the microchannel 4, and the extension direction of the microchannel 4 is serpentine. Preferably, the bends along the extension direction of the microchannel 4 are tapered bends, such as... Figure 3 and Figure 4 As shown.

[0125] Furthermore, the ratio of the width D of the straight flow channel 4 to the width d of the conical bend in the microchannel 4 is 1.5 to 3:1, for example, 2:1. Typically, the width D of the straight flow channel 4 is between 150 and 300 μm; preferably, it is between 180 and 250 μm; more preferably, it is 240 μm.

[0126] In this invention, an excessively narrow conical bend width d can increase the overall pressure drop of the chromatographic column, requiring a larger inlet pressure to allow complex gases (i.e., mixed gases) to flow through the column channel, thus reducing the column's efficiency. Conversely, an excessively wide conical bend width d can cause diffusion as the gas flows through the bend, easily resulting in tailing and peak broadening, thereby reducing the column's separation performance.

[0127] According to the present invention, such as Figure 4As shown, the conical bend includes a first bend 41, a second bend 42, a third bend 43, a fourth bend 44, and a fifth bend 45. These bends are sequentially connected. The second bend 42 and the fourth bend 44 are symmetrically distributed on both sides of the axis of the substrate 1 between the straight channels of the microchannel 4. The first bend 41 and the fifth bend 45 are also symmetrically distributed on both sides of the axis of the substrate 1 between the straight channels of the microchannel 4. The first bend 41 has a radius of r... 41 The diameter is 180–220 μm, and the second bend 42 has a diameter of r. 42 The diameter is 20-40 μm, and the r of the third bend 43 is... 43 The diameter is 120–170 μm, and the r of the fourth bend 44 is... 44 Preferred and r 42 Similarly, the fifth curve 45's r 45 Preferred and r 41 The same; for example, the r of the first bend 41 41 The value is 200μm, and the second bend 42 has an r value of 42. 42 The third bend 43 has a diameter of 30 μm and a diameter of 30 μm. 43 The fourth bend 44 has a diameter of 150 μm and a diameter of 150 μm. 44 With r 42 Similarly, the fifth curve 45's r 45 With r 41 Same, such as Figures 2 to 4 As shown.

[0128] The inventors have discovered that using the conical bend can effectively reduce the half-peak width, solving the problems of wide peaks and easy tailing in existing microchannel structures.

[0129] In this invention, the width L of the substrate 1 between the straight channels of the microchannel 4 is 100-140 μm, preferably 110-130 μm, for example 120 μm. The width L affects the effective width of the microchannel, and if the width is too small, it is easy to break during etching, making it impossible to form a serpentine channel.

[0130] According to the present invention, the straight channel portion of the microchannel 4 is provided with an array of columns 3. Along the extension direction of the microchannel 4 (denoted as the longitudinal spacing M of the columns 3), the distance between the columns 3 is 50–60 μm, preferably 52–58 μm, for example, 55 μm; along the direction perpendicular to the straight channel of the microchannel 4 (denoted as the transverse spacing N of the columns 3), the distance between the columns 3 is 30–45 μm, preferably 35–40 μm, for example, 38 μm; the columns 3 are any one or more of cylindrical, cuboid, and elliptical shapes, preferably cylindrical. Taking a cylindrical shape as an example, the diameter of the columns 3 is 25–35 μm, preferably 28–32 μm, for example, 30 μm. If the diameter of the columns 3 is too small, they are prone to breakage during deep dry etching, making it impossible to form a uniformly arranged array of columns 3. If the diameter of the columns 3 is too large, the overall number of columns 3 in the chromatographic column decreases, failing to effectively increase the specific surface area of ​​the microchannel 4. To improve the uniformity of column distribution along the microchannel 4 and the vertical direction, and to reduce peak tailing, the above-mentioned longitudinal spacing M and transverse spacing N parameters are suitable.

[0131] Furthermore, along the direction perpendicular to the microchannel 4 and the straight channel, the column 3 has 2 to 5 rows, preferably 3 to 4 rows, for example 3 rows. Too many rows of column 3 will cause the overall pressure drop of the chromatographic column to increase, while too few rows will not be able to significantly increase the specific surface area of ​​the microchannel 4.

[0132] In this invention, the pillars 3 are arranged in an array and symmetrically distributed in the microchannels 4; furthermore, the distance O between the pillars 3 near the substrate 1 along the extension direction of the microchannels 4 and the substrate 1 is not subject to many requirements, and is determined based on the width D of the straight channel of the microchannels 4, the size of the pillars 3, and the lateral spacing N, such as... Figure 3 As shown.

[0133] In one embodiment, the width D of the straight channel of the microchannel 4 is 240 μm. Along the direction perpendicular to the straight channel of the microchannel 4, there are 3 rows of pillars 3. The distance between each row (the lateral spacing N of the pillars 3) is 38 μm. The pillars 3 are cylindrical with a diameter of 30 μm. Along the extension direction of the microchannel 4 (the longitudinal spacing M of the pillars 3), the distance between the pillars 3 is 55 μm. The distance O between the pillar 3 near the substrate 1 along the extension direction of the microchannel 4 and the substrate 1 is 37 μm.

[0134] According to the present invention, the pillar 3 is shorter than the substrate 1, the upper surface of the pillar 3 is flush with the upper surface of the substrate 1 and the upper surface of the microchannel 4, the lower surface of the pillar 3 is above the lower surface of the substrate 1, and the lower surface of the pillar 3 is flush with the lower surface of the microchannel 4; the height of the cover plate 5 is preferably the same as the height of the substrate 1. Further, the height of the substrate 1 is typically 400–600 μm, preferably 450–550 μm, for example 500 μm; the height of the pillar 3 is 150–400 μm, preferably 170–300 μm, for example 200 μm, and the height of the pillar 3 is the depth to which the microchannel 4 is etched on the substrate 1. The larger the ratio of the etched microchannel 4 depth to the straight channel D of the microchannel 4, the better its separation performance; however, the diameter of the pillar 3 must also be considered, and the above parameter range is more suitable.

[0135] According to the present invention, the dimensions of the cover plate 5 are preferably the same as the dimensions of the outer contour of the substrate 1. The cover plate 5 is a borosilicate anolyte glass.

[0136] Furthermore, the cover plate 5 is bonded to the surface of the substrate 1. Preferably, after the cover plate 5 is bonded to the surface of the substrate 1, the bonded structure can be diced to obtain multiple chromatographic columns, thereby improving production efficiency.

[0137] In this invention, the temperature control unit 6 is disposed at the bottom of the silicon dioxide layer of the substrate 1. Multiple sets of temperature control units 6 can be provided. For example, 2 to 3 sets of temperature control units 6 are provided at intervals of 10 to 20 μm along the extension direction of the microchannel 4. Each set of temperature control units includes one temperature measuring electrode 61 and two heating wires 62. The number of sets of temperature control units 6 is specifically determined according to the width D of the straight flow channel of the microchannel 4. Usually, two sets of temperature control units 6 are provided.

[0138] In this invention, the temperature measuring electrode 61 is used to monitor the temperature; the heating wire 62 is used for heating; and 2 to 3 sets of temperature control units 6 are arranged horizontally along the vertical direction of the straight flow channel 4 at certain intervals, as shown in Figure 1(e).

[0139] According to the present invention, coating the composite stationary phase material 7 onto the inner wall of the microchannel 4 includes the following steps:

[0140] Step i: Roughen the inner wall of the microchannel 4;

[0141] Step ii: Coat the inner wall of the microchannel 4 with the composite stationary phase material 7;

[0142] Step iii: Aging treatment is performed on the inner wall of the microchannel 4 coated with composite stationary phase material 7.

[0143] In step i, the inner wall of the microchannel 4 is roughened to facilitate better adhesion between the composite stationary phase material 7 and the inner wall of the microchannel 4. Roughening is typically performed using a corrosive solution, the type of which depends on the material of the substrate 1. Taking a substrate 1 comprising a silicon layer 11 and a silicon dioxide layer 12, with the silicon layer 11 located above the silicon dioxide layer 12, as an example, the microchannel 4 is etched into the silicon layer 11. In this case, an APM solution is preferably used to roughen the inner wall of the microchannel 4, removing the oxide layer on the silicon surface. The APM solution is prepared using a specific ratio of alkali and hydrogen peroxide. An oxide film is formed on the silicon surface due to the oxidation of hydrogen peroxide, and this oxide film is then etched by the alkali. Immediately after etching, oxidation occurs again. This repeated oxidation and etching process achieves the roughening effect.

[0144] In step i, the base is a weak base, such as ammonia. In one embodiment, the APM is prepared by mixing 1% ammonia and 1% hydrogen peroxide in a volume ratio of 1:1.

[0145] In this invention, the roughening time does not need to be too long, usually 3 to 10 minutes is sufficient, for example 5 minutes.

[0146] In this invention, the APM prepared by using ammonia water as alkali and hydrogen peroxide decomposes into ammonia gas and water during the later inertization and / or aging treatments, without affecting the subsequent reactions.

[0147] In step ii, the composite stationary phase material 7 is dissolved in an organic solvent and ultrasonically treated to obtain a coating liquid, which is then coated onto the inner wall of the microchannel 4.

[0148] In this invention, the organic solvent is any one or more of methanol, ethanol, acetone, diethyl ether, and chloroform, preferably ethanol, which is safe, non-toxic, and volatile.

[0149] Furthermore, the concentration of the composite stationary phase material 7 in the coating solution directly affects the thickness of the composite stationary phase material 7 on the inner wall of the microchannel 4 after coating. If the composite stationary phase material 7 is too thick or too thin, it will hinder its adsorption and desorption from the mobile phase, thus affecting the separation performance of the chromatographic column. The concentration of the composite stationary phase material 7 in the coating solution is 3–12 mg / ml, preferably 4–10 mg / ml, for example, 5 mg / ml.

[0150] Further, the coating process includes: using nitrogen gas at 0.15–0.2 MPa to push the coating solution into the micro-chromatographic column to fill the microchannels 4, and allowing it to stand for 2 hours; then using a negative pressure buffer device to raise the temperature in the chromatographic column to 60–100°C, preferably 70–90°C, for example 80°C, to slowly evaporate the organic solvent in the composite stationary phase solution. However, raising the temperature inside the chromatographic column too high using a negative pressure buffer device will cause the organic solvent dissolving the composite stationary phase material 7 to evaporate rapidly, resulting in boiling over and preventing the composite stationary phase material 7 from being uniformly coated on the inner wall of the microchannels 4.

[0151] In one embodiment, the coating process includes: filling a buffer bottle with a coating solution, connecting one end of the buffer bottle to nitrogen gas and the other end to one port of a microchannel 4, and sealing the other port of the microchannel 4; using nitrogen gas at a pressure of 0.15–0.2 MPa to push the coating solution in the buffer bottle into the chromatographic column; after the coating solution fills the microchannel 4, turning off the nitrogen gas and disconnecting the chromatographic column from the buffer bottle; then simultaneously sealing the first and second ports of the chromatographic column and allowing it to stand for 2 hours; then, continuing to seal one port of the microchannel 4, and connecting the other port to a negative pressure buffer device and heating it to 60–100°C for 2–6 hours to allow the organic solvent, such as ethanol, in the coating solution to slowly evaporate.

[0152] In step ii, optionally, before coating, a silane coupling agent such as phenyltris(dimethylsiloxy)silane, octamethylcyclotetrasiloxane, etc., preferably phenyltris(dimethylsiloxy)silane, is used to inertize and deactivate the inner wall of the microchannel 4 at 180–280°C for 40–120 min, preferably, at 200–250°C for 60–100 min, and more preferably, at 220°C for 90 min.

[0153] In this invention, the inactivation treatment helps to shield the active sites of hydroxyl groups, reduce the adsorption of polar substances by the chromatographic column, and improve the separation effect of the chromatographic column for polar substances such as alcohols. The silane coupling agent, especially phenyltris(dimethylsiloxy)silane, is covalently bonded to the silanol group and releases hydrogen gas as a byproduct, making the overall reaction relatively mild.

[0154] In step iii, the aging treatment includes: holding at 160–250°C for 0.5–4 hours in an inert gas; preferably, the aging treatment includes: holding at 180–210°C for 1–3 hours in an inert gas; more preferably, the aging treatment includes: holding at 200°C for 2 hours in an inert gas.

[0155] However, if the aging temperature is too low or the aging time is too short, residual contaminants in the chromatographic column cannot be completely removed, thus failing to achieve the desired aging effect. Conversely, if the temperature is too high or the aging time is too long, the stationary phase will be lost, affecting the separation performance of the chromatographic column. Within the above-mentioned aging parameter range, the prepared chromatographic column exhibits excellent separation performance for complex gases.

[0156] The inert gas may be argon, neon or nitrogen, with nitrogen being the preferred inexpensive and readily available.

[0157] Fifthly, the present invention aims to provide a method for preparing a chromatographic column, the method comprising:

[0158] Microchannels 4 are etched in substrate 1, and pillars 3 are formed in microchannels 4;

[0159] The cover plate 5 is bonded to the surface of the substrate 1 and covers the microchannel 4, forming a chamber through the cover plate 5 and the microchannel 4;

[0160] A temperature control unit 6 is provided at the bottom of substrate 1;

[0161] The composite stationary phase material 7 is coated on the inner wall of the microchannel 4.

[0162] Specifically:

[0163] like Figures 1(a) to 1(f) As shown, a patterned photoresist masking layer 2 is formed on the surface of a substrate 1, such as a silicon layer 11. Based on the photoresist masking layer 2, microchannels 4 are etched using a deep dry etching method. Columns 3 are arranged in an array in the straight sections of the microchannels 4. The etched substrate 1 and cover plate 5 are immersed in an RCA-2 solution (e.g., hydrochloric acid: hydrogen peroxide: water (volume ratio) = 1:1:6). The cover plate 5 is then bonded to the surface of the substrate 1 and covers the microchannels 4 to form a chamber. Optionally, the bonded structure is diced. The size of the cover plate 5 is preferably the same as the outer contour of the substrate 1. A temperature control unit 6 is set at the bottom of the substrate 1, such as the bottom of a silicon dioxide layer 12. For example, a patterned photoresist masking layer 2 is formed at the bottom of the substrate 1, such as the bottom of a silicon dioxide layer 12. The temperature control unit 6 is set at the bottom of the substrate 1, such as the bottom of a silicon dioxide layer 12, using back-overlay, electron beam evaporation, and stripping methods. A composite stationary phase material 7 is coated on the inner wall of the microchannels 4 to obtain the chromatographic column.

[0164] Example

[0165] The present invention is further described below through specific examples; however, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0166] Example 1

[0167] (1) Preparation of composite stationary phase materials

[0168] Add 10 mg of [P66614][NTf2] to 50 g of acetone and stir with a magnetic stirrer at 500 rpm at room temperature (25°C). -1 Then add 5mg ZIF-8 and sonicate at 80W for 40min to obtain a mixed solution;

[0169] The mixture was sealed with a Parafilm membrane and stirred at 40°C and a stirring rate of 800 r·min using a magnetic stirrer. -1 Stir for 10 hours, then remove the Parafilm membrane and incubate at 40°C with a stirring rate of 1000 rpm. -1 Stir for 5 hours, then adjust the temperature to 60℃ and stir at a speed of 1000 r·min. -1 The mixture was stirred for 2 hours, and then dried in a vacuum drying oven at 100°C for 2 hours. The mixture was then ground to a particle size of 80 μm to obtain the composite stationary phase material.

[0170] The composite stationary phase material was characterized by SEM as follows: Figure 5 As shown, the surface morphology of the composite stationary phase material is a hexagon with a diameter of approximately 60 nm, which is basically consistent with the appearance of the ZIF-8 material. Some [P6614][NTf2] exists on the surface of ZIF-8, making the boundaries of the composite particles indistinct. No agglomeration was observed overall; the specific surface area of ​​the prepared composite stationary phase material is 1062.42 m². 2 / g, the pore size of the composite stationary phase material is 0.345nm.

[0171] (2) Preparation of chromatographic column

[0172] like Figures 1(a) to 1(f)As shown, a patterned photoresist masking layer 2 is formed on the surface of the silicon layer 11 (height 480μm) of a single-sided oxidized and double-sided polished four-inch silicon wafer substrate 1 (height 500μm). Microchannels 4 are etched based on the photoresist masking layer 2, with a depth of 200μm. Each microchannel 4 has a first port and a second port, both connected to a quartz capillary. The extension direction of the microchannel 4 is serpentine, with tapered bends at the bends. The width D of the straight channel of the microchannel 4 is 240μm, and the straight channel is perpendicular to the microchannel 4. In the direction of the microchannel 4, there are 3 rows of pillars 3, and the distance between each row (the horizontal spacing N of the pillars 3) is 38 μm. The pillars 3 are cylindrical with a diameter of 30 μm. Along the extension direction of the microchannel 4 (the longitudinal spacing M of the pillars 3), the distance between the pillars 3 is 55 μm. The width L of the substrate 1 between the straight channels of the microchannel 4 is 120 μm. The distance O between the pillar 3 near the substrate 1 along the extension direction of the microchannel 4 and the substrate 1 is 37 μm. The width d of the tapered bend of the microchannel 4 is 120 μm. The first bend 41 has a diameter of r. 41 The value is 200μm, and the second bend 42 has an r value of 42. 42 The third bend 43 has a diameter of 30 μm and a diameter of 30 μm. 43 The fourth bend 44 has a diameter of 150 μm and a diameter of 150 μm. 44 With r 42 Similarly, the fifth curve 45's r 45 With r 41 same;

[0173] The etched substrate 1 and cover plate 5 (made of four-inch high borosilicate anode bonding glass) are immersed in RCA-2 solution (hydrochloric acid: hydrogen peroxide: water (volume ratio) = 1:1:6). Then, the cover plate 5 is bonded (bonding temperature set at 250°C, bonding voltage set at 600V) to the surface of the substrate 1 and covers the microchannel 4 to form a chamber. The bonded structure is mechanically diced. The size of the cover plate 5 is the same as the size of the outline of the unetched substrate 1.

[0174] A patterned photoresist masking layer 2 is formed at the bottom of the silicon dioxide layer 12 of the substrate 1. A 50nm thick gold conductive film is formed at the bottom of the silicon dioxide layer 12 by back-mounting, electron beam evaporation and stripping. A temperature control unit 6 is set on the gold conductive film. Two sets of temperature control units 6 are set at 15μm intervals along the extension direction of the microchannel 4. The two sets of temperature control units 6 are arranged horizontally along the vertical direction of the straight channel. Each set of temperature control units includes one temperature measuring electrode 61 and two heating wires 62.

[0175] The inner wall of the microchannel 4 was roughened for 5 minutes using APM (1% ammonia water: 1% hydrogen peroxide (volume ratio) = 1:1) solution to remove the oxide layer on the surface of silicon layer 11. The composite stationary phase material obtained in step (1) was dissolved in ethanol to prepare a coating solution with a concentration of 5 mg / ml.

[0176] The inner wall of microchannel 4 was inertized and deactivated at 220°C for 90 min using phenyltris(dimethylsiloxy)silane.

[0177] The coating solution was loaded into a buffer bottle, one end of which was connected to nitrogen gas, and the other end was connected to the first port of microchannel 4. The second port of microchannel 4 was sealed. Using nitrogen gas at a pressure of 0.15 MPa, the coating solution (concentration 5 mg / ml) in the buffer bottle was pushed into the chromatographic column. After the coating solution filled microchannel 4, the nitrogen gas was turned off, and the connection between the chromatographic column and the buffer bottle was disconnected. The first and second ports of the chromatographic column were sealed and allowed to stand for 2 hours. Then, the first port of microchannel 4 was kept sealed, and the second port was connected to a negative pressure buffer device and heated to 80°C for 4 hours to allow the ethanol in the coating solution to completely evaporate. The connection between the second port of microchannel 4 and the negative pressure buffer device was disconnected, and the first port was connected to an empty buffer bottle. Nitrogen gas was introduced and the column was kept at 200°C for 2 hours to complete the coating of the inner wall of microchannel 4, thus obtaining the chromatographic column.

[0178] The obtained partial SEM image of the chromatographic column is shown below. Figure 2 As shown, Figure 3 Show Figure 2 Three-dimensional SEM characterization of part B, Figure 4 Show Figure 2 Enlarged view of part A.

[0179] (3) The prepared chromatographic column was used to separate the alkane mixture (pentane, hexane, heptane, octane, nonane, decanane, undecane, and dodecane, labeled C5, C6, C7, C8, C9, C10, C11, and C12 in the figure, respectively). The chromatographic column based on the composite stationary phase material can achieve two-stage separation of the alkane mixture: the first stage separation mainly divides the alkane mixture into two categories based on the pore size of the ZIF-8 column: gases with larger molecular dynamic diameters (C8, C9, C10, C11, and C12) and gases with smaller molecular dynamic diameters (C5, C6, and C7). In the second stage separation, the ionic liquid [P66614][NTf2] plays a major role in separating the gases with larger molecular dynamic diameters (C8, C9, C10, C11, and C12) and the gases with smaller molecular dynamic diameters (C5, C6, and C7). The separation effect is shown in the figure. Figure 8 As shown.

[0180] Example 2

[0181] (1) Preparation of composite stationary phase materials

[0182] Add 6 mg of [P66614][NTf2] to 50 g of acetone and stir with a magnetic stirrer at room temperature (25°C) at a stirring speed of 480 rpm. -1 Then add 4 mg ZIF-8 and sonicate at 90 W for 35 min to obtain a mixed solution;

[0183] The mixture was sealed with a Parafilm membrane and stirred at 40°C and a stirring rate of 750 r·min using a magnetic stirrer. -1 Stir for 10 hours, then remove the Parafilm membrane and incubate at 40°C with a stirring rate of 1000 rpm. -1 Stir for 5 hours, then adjust the temperature to 60℃ and stir at a speed of 1100 r·min. -1 The mixture was stirred for 2 hours, and then dried in a vacuum drying oven at 100°C for 2 hours. The mixture was then ground to a particle size of 80 μm to obtain the composite stationary phase material.

[0184] The specific surface area of ​​the prepared composite stationary phase material is 900.12 m². 2 / g, the pore size of the composite stationary phase material is 0.426nm.

[0185] (2) Prepare the chromatographic column in the same manner as in step (2) of Example 1.

[0186] Subsequently, the prepared chromatographic column was used to separate the alkane mixture (pentane, hexane, heptane, octane, nonane, decanane, undecane, and dodecane, labeled C5, C6, C7, C8, C9, C10, C11, and C12, respectively), and the separation results are shown in Table 1.

[0187] Example 3

[0188] (1) Preparation of composite stationary phase materials

[0189] Add 10 mg of [P66614][NTf2] to 50 g of acetone and stir with a magnetic stirrer at 520 r / min at room temperature (25°C). -1 Then add 4 mg ZIF-8 and sonicate at 70 W for 45 min to obtain a mixed solution;

[0190] The mixture was sealed with a Parafilm membrane and stirred at 40°C and a stirring rate of 850 r·min using a magnetic stirrer. -1 Stir for 10 hours, then remove the Parafilm membrane and incubate at 40°C with a stirring rate of 1000 rpm. -1Stir for 5 hours, then adjust the temperature to 60℃ and maintain a stirring speed of 950 r·min. -1 The mixture was stirred for 2 hours, and then dried in a vacuum drying oven at 100°C for 2 hours. The mixture was then ground to a particle size of 80 μm to obtain the composite stationary phase material.

[0191] The specific surface area of ​​the prepared composite stationary phase material is 1109.83 m². 2 / g, the pore size of the composite stationary phase material is 0.243nm.

[0192] (2) Prepare the chromatographic column in the same manner as in step (2) of Example 1.

[0193] Subsequently, the prepared chromatographic column was used to separate the alkane mixture (pentane, hexane, heptane, octane, nonane, decanane, undecane, and dodecane, labeled C5, C6, C7, C8, C9, C10, C11, and C12, respectively), and the separation results are shown in Table 1.

[0194] Comparative Example

[0195] Comparative Example 1

[0196] The [P66614][NTf2] single-phase material was prepared using a method similar to step (1) of Example 1, except that ZIF-8 was not added;

[0197] The chromatographic column was prepared using a method similar to step (2) of Example 1, the difference being that the chromatographic column adopted a circular curved channel structure, and the resulting partial SEM image of the chromatographic column is shown in Figure 1. Figure 6 As shown, Figure 7 Show Figure 6 Enlarged view of part C, where R1 = 300 μm and R2 = 125 μm.

[0198] Using the chromatographic column described in this example, a mixture of alkane gases (pentane, hexane, heptane, octane, nonane, decanane, undecane, and dodecane, labeled C5, C6, C7, C8, C9, C10, C11, and C12 in the figure) was separated, and the separation effect is as follows. Figure 9 As shown.

[0199] Combination Figure 8 and Figure 9It can be seen that the chromatographic column described in Example 1 significantly improves the classification of alkanes compared to the chromatographic column described in Comparative Example 1. The composite stationary phase material prepared in Example 1 has a high specific surface area, thus effectively improving the unit column efficiency. Simultaneously, the metal-organic framework ZIF-8 acts as a molecular sieve, effectively classifying gases based on their molecular dynamic diameters. Then, the ionic liquid stationary phase [P66614][NTf2] can separate the molecules of each gas class, achieving two-stage separation. The chromatographic column based on the single ionic liquid stationary phase [P66614][NTf2] in Comparative Example 1 cannot separate pentane and hexane, while the chromatographic column based on the composite stationary phase in Example 1 can efficiently separate pentane and hexane, with a resolution of 1.670. The resolution comparison of adjacent components is shown in Table 1, revealing a significant improvement in the resolution of adjacent components in Example 1 compared to Comparative Example 1.

[0200] Table 1: Comparison of resolution between Comparative Example 1 and Example 1

[0201]

[0202] Meanwhile, the conical bend in Example 1 can reduce the diffusion of the mixed gas at the bend, thereby effectively reducing the half-peak width. Taking heptane as an example, the half-peak width of the column in Comparative Example 1 for heptane is 0.322, while the half-peak width of the column in Example 1 for heptane is 0.174, a reduction of 47%. The comparison of the half-peak widths of each component is shown in Table 2. It can be found that compared with Comparative Example 1, the half-peak widths of each component in Example 1 are significantly reduced.

[0203] Table 2: Comparison of half-peak width between Comparative Example 1 and Example 1

[0204]

[0205] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are merely illustrative explanations of the invention and do not constitute any limitation on the scope of protection of the invention. Various improvements, equivalent substitutions, or modifications can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of protection of the invention, and all such modifications fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A chromatographic column, characterized in that, The chromatographic column includes: Substrate (1); Microchannels (4) are located in the substrate (1); A column (3) is located in the microchannel (4); A cover plate (5) is located on the surface of the substrate (1) and covers the microchannel (4), forming a chamber through the cover plate (5) and the microchannel (4); A composite stationary phase material (7) is coated on the inner wall of a microchannel (4). The extension direction of the microchannel (4) is serpentine, and a conical bend is adopted at the bend along the extension direction of the microchannel (4). The ratio of the width D of the straight flow channel of the microchannel (4) to the width d of the conical bend is 1.5~3:

1. The conical bend includes a first bend (41), a second bend (42), a third bend (43), a fourth bend (44) and a fifth bend (45) connected in sequence. The second bend (42) and the fourth bend (44) are symmetrically distributed on both sides of the axis of the substrate (1) between the straight flow channels of the microchannel (4). The first bend (41) and the fifth bend (45) are symmetrically distributed on both sides of the axis of the substrate (1) between the straight flow channels of the microchannel (4). r of the first bend (41) 41 The second bend (42) has a diameter of 180~220µm and an angle of r of 180~220µm. 42 The third bend (43) has a diameter of 20~40µm. 43 The fourth bend (44) has a diameter of 120~170µm. 44 With r 42 Similarly, the fifth bend (45) of r 45 With r 41 same; The composite stationary phase material (7) is used to separate gas components of pentane, hexane, heptane, octane, nonane, decane, undecane and dodecane; The specific surface area of ​​the composite stationary phase material (7) is between 900 and 1100 m². 2 Between / g; The composite stationary phase material (7) comprises an ionic liquid stationary phase and a metal-organic framework; the ionic liquid stationary phase is selected from any one or more of trihexyl(tetradecyl)phosphine bis(trifluoromethanesulfonyl)amine ([P66614][NTf2]), trihexyltetradecylphosphine chloride ([P66614][Cl]), and 1-butyl-3-methylimidazolium tetrafluoroboronic acid ([Bmim][BF4]); the metal-organic framework is a zeolite imidazolium ester framework; the mass ratio of the ionic liquid stationary phase to the metal-organic framework is (1~3):1; The composite stationary phase material (7) first uses the metal-organic framework as a molecular sieve and performs preliminary classification of gases according to the molecular dynamic diameter of different gases, separating the gas components into two major categories: gases with larger molecular dynamic diameters and gases with smaller molecular dynamic diameters. The gases with larger molecular dynamic diameters include octane, nonane, decane, undecane, and dodecane, while the gases with smaller molecular dynamic diameters include pentane, hexane, and heptane. Then, the composite stationary phase material uses an ionic liquid stationary phase to separate the molecules of each type of gas to achieve two-stage separation.

2. The chromatographic column according to claim 1, characterized in that, The metal-organic framework is ZIF-8, ZIF-11, or ZIF-64.

3. The chromatographic column according to claim 1, characterized in that, The composite stationary phase material has a porous structure, wherein the cations and anions in the ionic liquid stationary phase are distributed within the pores of the metal-organic framework.

4. The chromatographic column according to claim 1, characterized in that, The mass ratio of the ionic liquid stationary phase to the metal-organic framework in the composite stationary phase material is (1.5~2.5):

1.

5. The chromatographic column according to claim 1, characterized in that, The preparation method of the composite stationary phase material (7) includes: Step 1: Prepare the ionic liquid solution; Step 2: Add a metal-organic framework to the ionic liquid solution to obtain a mixed solution; Step 3: Post-process the mixed solution to obtain the composite stationary phase material.

6. The chromatographic column according to claim 5, characterized in that, In step 3, the post-processing includes stirring, drying, and grinding.

7. The chromatographic column according to claim 1, characterized in that, The composite stationary phase material (7) is coated onto the inner wall of the microchannel (4) in the following steps: Step i, roughen the inner wall of the microchannel (4); Step ii: Coat the inner wall of the microchannel (4) with the composite stationary phase material (7); Step iii: The inner wall of the microchannel (4) coated with composite stationary phase material (7) is subjected to aging treatment.

8. A method for preparing the chromatographic column according to claim 1, characterized in that, The method includes: Microchannels (4) are etched in the substrate (1), and pillars (3) are formed in the microchannels (4). The cover plate (5) is bonded to the surface of the substrate (1) and covers the microchannel (4) to form a chamber; The composite stationary phase material (7) is coated on the inner wall of the microchannel (4).

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