Micro-chromatographic column for light hydrocarbon separation and method of making same

Abstract

The application provides a micro chromatographic column for light hydrocarbon separation and a preparation method thereof, and the micro chromatographic column is prepared from FG and HKUST-1 to obtain FG-HKUST-1 stationary phase, and the FG-HKUST-1 stationary phase is non-polar material; in addition to having a screening effect on C1-C4 light hydrocarbon, further, there is a dispersion force between the non-polar FG-HKUST-1 stationary phase and non-polar light hydrocarbon, such as non-polar methane and ethane, so that the non-polar FG-HKUST-1 stationary phase has strong retention capacity for non-polar light hydrocarbon, thereby the resolution of C1-C4 light hydrocarbon can be improved, especially for light hydrocarbon with low resolution, large concentration difference and similar properties, such as methane and ethane, so that the application can meet the requirements of qualitative and quantitative analysis and detection of light hydrocarbon.

Description

Technical Field

[0001] This invention belongs to the field of microelectromechanical systems and relates to a microchromatographic column for the separation of light hydrocarbons and its preparation method. Background Technology

[0002] Gas chromatography (GC), a common analytical technique, has been widely applied in fields such as petrochemicals, pharmaceutical testing, energy exploration, and environmental monitoring. The core component of a GC is the chromatographic column, which separates mixed gas samples. In the entire testing system, the column plays a crucial role in separating the mixed gases, and its performance directly affects the analytical results of the entire instrument. The separation effect of the column primarily relies on the stationary phase coated on the inner surface of the channel. The stationary phase has different adsorption and desorption capacities for different gases, resulting in different flow velocities of the different analyte gas components within the channel. Ultimately, the different gas components reach the column outlet at different times, thus achieving the separation of the mixed gas.

[0003] Traditional chromatographic columns require a large oven to heat and maintain a stable temperature, resulting in a large overall size, high power consumption, and difficulty in meeting the needs of real-time separation and detection. Therefore, the key to the miniaturization of the entire chromatographic instrument lies in the miniaturization of the chromatographic column.

[0004] Since the late 1970s, researchers have been exploring the fabrication of microchromatographic columns on silicon wafers using microelectromechanical systems (MEMS) technology through etching. To improve the separation efficiency of silicon-based microchromatographic columns, researchers have made significant progress in optimizing their geometry. One notable advancement is the design of microcolumn arrays within the column channels to further increase the internal surface area, creating a semi-filled column structure that enhances separation performance. On the other hand, the stationary phase is another crucial factor influencing separation efficiency. Materials such as polydimethylsiloxane, alumina nanoparticles, and mesoporous silica have been used as stationary phases for silicon-based microchromatographic columns. However, these materials exhibit low resolution in the separation of light hydrocarbons, particularly methane and ethane, with a short retention time difference. When the methane concentration in a sample is significantly higher than that of ethane (e.g., in natural gas), the methane peak may overwhelm the ethane peak, hindering qualitative and quantitative analysis of light hydrocarbons like methane and ethane.

[0005] Therefore, it is necessary to provide a microchromatographic column for the separation of light hydrocarbons and its preparation method. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a microchromatographic column for the separation of light hydrocarbons and its preparation method, so as to solve the problem that microchromatographic columns in the prior art are difficult to effectively separate light hydrocarbons.

[0007] To achieve the above and other related objectives, the present invention provides a microchromatographic column for the separation of light hydrocarbons, the microchromatographic column comprising:

[0008] Substrate;

[0009] A microchannel located in the substrate, the microchannel having a first port and a second port;

[0010] Micropillars are located in the microchannels, comprising n columns of micropillars spaced apart along the width of the microchannels and m rows of micropillars spaced apart along the extension of the microchannels, to form an n×m micropillar array.

[0011] A cover plate, located on the surface of the substrate and covering the microchannel, forming a closed microchannel;

[0012] The FG-HKUST-1 stationary phase covers the inner surface of the closed microchannel. The materials forming the FG-HKUST-1 stationary phase include fluorinated graphene (FG) and metal-organic framework (MOF) material HKUST-1. The FG-HKUST-1 stationary phase has a sieving effect and is a non-polar material.

[0013] Optionally, the light hydrocarbons include C1 to C4 alkanes.

[0014] Optionally, the operating temperature of the microchromatographic column is below 300°C.

[0015] Optionally, the micropillar includes an elliptical micropillar or a circular micropillar. When the micropillar is an elliptical micropillar, the major axis of the elliptical micropillar is parallel to the extension direction of the microchannel, and the minor axis of the elliptical micropillar is parallel to the width direction of the microchannel.

[0016] Optionally, the cover plate includes a glass cover plate, a silicon cover plate, or a ceramic cover plate.

[0017] Optionally, the morphology of the microchannel includes one of the following: serpentine extension, zigzag extension, U-shaped extension, and spiral extension.

[0018] This invention also provides a method for preparing a microchromatographic column for the separation of light hydrocarbons, comprising the following steps:

[0019] A substrate is provided, and a patterned mask layer is formed on the surface of the substrate;

[0020] The substrate is etched based on the patterned mask layer to form microchannels and micropillars in the substrate. The microchannels have a first port and a second port. The micropillars are located in the microchannels and include n columns of the micropillars spaced apart along the width direction of the microchannels and m rows of the micropillars spaced apart along the extension direction of the microchannels to form an n×m micropillar array.

[0021] A cover plate is provided and bonded to the surface of the substrate to cover the microchannel, forming a closed microchannel;

[0022] An FG-HKUST-1 stationary phase is formed, which covers the inner surface of the closed microchannel. The material forming the FG-HKUST-1 stationary phase includes fluorinated graphene (FG) and metal-organic framework (MOF) material HKUST-1. The FG-HKUST-1 stationary phase has a sieving effect and is a non-polar material.

[0023] Optionally, the step of forming the FG-HKUST-1 stationary phase includes:

[0024] FG-HKUST-1 powder is mixed with a solvent to form an FG-HKUST-1 solution;

[0025] The FG-HKUST-1 solution is injected into the closed microchannel from the first port and discharged through the second port to coat the closed microchannel with FG-HKUST-1 material.

[0026] An aging process is performed to transform the FG-HKUST-1 material into an FG-HKUST-1 stationary phase covering the inner surface of the closed microchannels.

[0027] Optionally, the steps for preparing the FG-HKUST-1 powder include:

[0028] FG powder was placed in N,N-dimethylformamide (DMF) solvent, ultrasonically dispersed, and the supernatant was collected after standing.

[0029] A mixed solution was obtained by adding dimethyl sulfoxide (DMSO) solvent to Cu(NO3)2·3H2O powder and pyromellitic acid (H3BTC) powder and dispersing and dissolving them by ultrasonication.

[0030] The supernatant and the mixed solution were added to the CH3OH solution, and the mixture was stirred and centrifuged to obtain the lower solid layer.

[0031] The FG-HKUST-1 powder was obtained by washing and drying with CH3OH solution.

[0032] Optionally, after bonding the cover plate and before forming the FG-HKUST-1 stationary phase, a dicing step is also included.

[0033] As described above, the microchromatographic column for light hydrocarbon separation and its preparation method of the present invention use FG and HKUST-1 to prepare the FG-HKUST-1 stationary phase of the microchromatographic column. The FG-HKUST-1 stationary phase is a non-polar material. In addition to having a sieving effect on C1 to C4 light hydrocarbons, the non-polar FG-HKUST-1 stationary phase has a dispersion force with non-polar light hydrocarbons, such as non-polar methane and ethane. This allows the non-polar FG-HKUST-1 stationary phase to have a strong retention capacity for non-polar light hydrocarbons, thereby improving the separation degree of C1 to C4 light hydrocarbons. This is especially true for light hydrocarbons with low separation degree, large concentration differences, and similar properties, such as methane and ethane. Therefore, the present invention can meet the requirements for qualitative and quantitative analysis and detection of light hydrocarbons. Attached Figure Description

[0034] Figure 1 The diagram shows the process flow chart for preparing the microchromatographic column in an embodiment of the present invention.

[0035] Figures 2-5 The diagram shows the structural schematics obtained in each step of preparing the microchromatographic column in an embodiment of the present invention.

[0036] Figure 6 The image shown is a scanning electron microscope image of the microchromatographic column in an embodiment of the present invention.

[0037] Figure 7 Displayed as Figure 6 A top-down magnified structural diagram of region A in the middle.

[0038] Figure 8a and Figure 8b The diagram shows a schematic of the process apparatus for preparing the FG-HKUST-1 stationary phase in an embodiment of the present invention.

[0039] Figure 9 The image shows a comparison of the pore size distribution of FG-HKUST-1 material and HKUST-1 material in an embodiment of the present invention.

[0040] Figure 10 The graph shows the thermogravimetric analysis results of the FG-HKUST-1 material in this embodiment of the invention.

[0041] Figure 11 The image shown is a result of a light hydrocarbon separation test performed using a microchromatographic column in an embodiment of the present invention.

[0042] Component designation explanation

[0043] 100 substrate

[0044] 110 Microchannel sidewall

[0045] 200 mask layers

[0046] 300 microchannel

[0047] 310 Microchannel First Port

[0048] 400 microcolumns

[0049] 500 cover plate

[0050] 600 Closed Microchannel

[0051] 610 Closed microchannel inner surface

[0052] 700 FG-HKUST-1 stationary phase

[0053] 1. High-pressure air source

[0054] 2 Pressure Bottles

[0055] 3. Stationary phase suspension

[0056] 4. Adapters

[0057] 5. Microchromatographic column

[0058] 6 capillaries Detailed Implementation

[0059] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0060] In the detailed description of embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0061] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include orientations of the device in use or operation other than those depicted in the drawings, and may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact. Furthermore, when a layer is referred to as “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0062] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0063] like Figure 1 As shown, this embodiment provides a method for preparing a microchromatographic column, including the following steps:

[0064] S1: Provide a substrate and form a patterned mask layer on the surface of the substrate;

[0065] S2: Based on the patterned mask layer, the substrate is etched to form microchannels and micropillars in the substrate. The microchannel has a first port and a second port. The micropillars are located in the microchannel and include n columns of the micropillars arranged at intervals along the width direction of the microchannel and m rows of the micropillars arranged at intervals along the extension direction of the microchannel to form an n×m micropillar array.

[0066] S3: Provide a cover plate and bond the cover plate to the surface of the substrate to cover the microchannel, forming a closed microchannel;

[0067] S4: Form an FG-HKUST-1 stationary phase, which covers the inner surface of the closed microchannel. The material forming the FG-HKUST-1 stationary phase includes FG (fluorinated graphene) and metal-organic framework (MOF) HKUST-1. The FG-HKUST-1 stationary phase has a sieving effect and is a non-polar material.

[0068] In this embodiment, the FG-HKUST-1 stationary phase of the microchromatographic column is prepared using the FG material and the HKUST-1 material. The FG-HKUST-1 stationary phase is a non-polar material. In addition to its sieving effect on C1-C4 light hydrocarbons, the non-polar FG-HKUST-1 stationary phase has a dispersion force with non-polar light hydrocarbons, such as non-polar methane and ethane. This allows the non-polar FG-HKUST-1 stationary phase to have a strong retention capacity for non-polar light hydrocarbons, thereby improving the resolution of C1-C4 light hydrocarbons. This is especially true for light hydrocarbons with low resolution, large concentration differences, and similar properties, such as methane and ethane, thus meeting the requirements for qualitative and quantitative analysis and detection of light hydrocarbons.

[0069] See Figures 2-7 The structure and preparation of the microchromatographic column are described below with reference to the accompanying drawings. Figure 6 This diagram shows a scanning electron microscope image of the microchromatographic column formed in this embodiment. Figure 2 and Figure 3 It can be understood as Figure 6 A schematic diagram of a locally enlarged cross-sectional structure of region A obtained along line C-C'. Figure 7 It indicated Figure 6 A top-down enlarged structural diagram of region A in the middle. Figure 4 This illustrates the cross-sectional structure of the microchromatographic column when it has a cover plate. Figure 5 This diagram illustrates the cross-sectional structure of the microchromatographic column after the formation of the FG-HKUST-1 stationary phase.

[0070] First, refer to Figure 1 and Figure 2 Step S1 is performed, a substrate 100 is provided, and a patterned mask layer 200 is formed on the surface of the substrate 100.

[0071] As an example, the substrate 100 may include a silicon substrate, a glass substrate, or a ceramic substrate; the mask layer 200 may include one or a combination of a silicon oxide mask layer, a silicon nitride mask layer, and a photoresist mask layer.

[0072] Specifically, the types of substrate 100 and mask layer 200 are not limited to these and can be selected as needed. In this embodiment, the substrate 100 is a silicon substrate and the mask layer 200 is a photoresist mask layer covering the substrate 100, but it is not limited to these.

[0073] As an example, forming a patterned mask layer 200 on the surface of the substrate 100 may include the following steps:

[0074] The photoresist mask layer is formed on the surface of the substrate 100;

[0075] The photoresist mask layer is patterned using photolithography and etching processes to obtain photoresist etching windows. These etching windows define the areas to be formed subsequently, such as... Figure 3 The shape and position of the microchannels 300 and micropillars 400 in the middle.

[0076] Next, refer to Figure 1 , Figure 3 and Figure 6 Step S2 is executed, whereby the substrate 100 is etched based on the patterned mask layer 200 to form the microchannel 300 and the micropillars 400 in the substrate 100. The microchannel 300 has a first port 310 and a second port (not shown). The micropillars 400 are located in the microchannel 300 and include n columns of the micropillars 400 spaced apart along the width direction of the microchannel 300 and m rows of the micropillars 400 spaced apart along the extension direction of the microchannel 300, to form an n×m micropillar array.

[0077] Specifically, in this embodiment, the exposed substrate 100 is etched using deep reactive ion etching (DRIE) technology to form the microchannels 300 and the micropillars 400 in the substrate 100. However, the etching method is not limited to this and can be adapted as needed.

[0078] As an example, the micropillar 400 includes an elliptical micropillar or a circular micropillar. When the micropillar 400 is an elliptical micropillar, the major axis of the elliptical micropillar is parallel to the extension direction of the microchannel, and the minor axis of the elliptical micropillar is parallel to the width direction of the microchannel.

[0079] Specifically, in this embodiment, the micropillar 400 is preferably an elliptical micropillar. By using an n×m elliptical micropillar array located in the microchannel 300, the area of ​​the "quasi-zero flow velocity region" formed after the micropillar can be greatly reduced, so that a uniform stationary phase can be coated on the micropillar 400, resulting in a uniform flow velocity distribution within the column.

[0080] See Figure 7In this embodiment, the width of the microchannel 300 is w, the effective width of the microchannel 300 is d, and n is 4. The microchannel 300 forms three sub-microchannels with a width of s and two sub-microchannels with a width of S, i.e., d = 3s + 2S. In fact, the number of columns, rows, and dimensions of the elliptical microcylinders can be selected according to actual needs. The number of columns n and rows m of the elliptical microcylinders located in the microchannel 300, the minor axis length q and major axis length p of the elliptical microcylinders, and the spacing S, s, and t, etc., can be selected as needed and will not be elaborated here. The preferred formula is q = (wd) / n, which adjusts the minor axis length q of the elliptical microcolumns while increasing the number of microcolumns. This effectively increases the internal surface area of ​​the column while keeping the width w and effective width d of the microchannel 300 constant, thereby improving the separation performance of the microchromatographic column. It also effectively solves the problem of increased column inlet pressure caused by the increase in the number of microcolumns. This allows the microchromatographic column to maintain a low column inlet pressure while effectively increasing the surface area, thus improving its efficiency, reducing the burden on the gas supply system, facilitating portable applications, and giving the microchromatographic column broad application prospects.

[0081] As an example, adjacent n columns of micropillars 400 are arranged at equal intervals along the width direction of the microchannel 300 to reduce process complexity; or, as needed, the n columns of micropillars can be arranged with different intervals along the width direction of the microchannel 300 to further make the flow velocity distribution within the column uniform and alleviate the problem of uneven carrier gas velocity.

[0082] As an example, along the width direction of the microchannel 300, the spacing s between adjacent n columns of micropillars 400 is smaller than the spacing S between the micropillars 400 located at the edge and the microchannel sidewall 110, i.e., S > s, so as to provide a uniform flow rate in the microchannel 300.

[0083] As an example, the formed microchannel 300 can extend in a serpentine shape. Of course, in other examples, the formed microchannel 300 can also extend in the substrate 100 in any way, such as zigzag extension, U-shaped extension, spiral extension, etc. There are no excessive restrictions here.

[0084] Next, refer to Figure 1 and Figure 4 In step S3, a cover plate 500 is provided and the cover plate 500 is bonded to the surface of the substrate 100 to cover the microchannel 300, forming a closed microchannel 600.

[0085] As an example, the cover plate 500 may include a glass cover plate, a silicon cover plate, or a ceramic cover plate, wherein preferably the cover plate 500 and the substrate 100 are made of the same material, so as to form a uniform stationary phase in the closed microchannel 600.

[0086] For details, please refer to Figure 4 The cover plate 500 can be bonded to the surface of the substrate 100 using an anodic bonding process. The bonding process conditions can be selected as needed, and no excessive restrictions are imposed here.

[0087] As an example, if multiple independent microchromatographic columns are formed within the substrate 100, after bonding the cover plate 500 to the surface of the substrate 100, the bonded structure can be diced to obtain multiple microchromatographic columns, thereby improving production efficiency. Then, capillaries can be installed at the first port 310 of the prepared microchannel 300, including the inlet and outlet ends (not shown), respectively. Figure 8a and Figure 8b This serves as the connection point with the external air passage, which will not be elaborated upon here.

[0088] Next, refer to Figure 1 and Figure 5 Step S4 is executed to form an FG-HKUST-1 stationary phase 700. The FG-HKUST-1 stationary phase 700 covers the inner surface 610 of the closed microchannel. The material forming the FG-HKUST-1 stationary phase 700 includes the FG material and the HKUST-1 material. The FG-HKUST-1 stationary phase 700 has a sieving effect and is a non-polar material.

[0089] For details, please refer to Figure 9The diagram illustrates a comparison of the pore size distributions of FG-HKUST-1 and HKUST-1 materials. HKUST-1 is a copper-based material with various pore sizes, including 0.6 nm, 0.69 nm, and 0.9 nm. FG-HKUST-1 also exhibits various pore sizes, including 0.69 nm, 0.9 nm, and a small number of pores larger than 1 nm. The 0.69 nm and 0.9 nm pores originate from HKUST-1, while the pores larger than 1 nm originate from slit-like pores formed between HKUST-1 and FG. Since the molecular dynamic diameters of methane, ethane, propane, and butane are 0.38 nm, 0.40 nm, 0.42 nm, and 0.43 nm, respectively, all smaller than the characteristic pore size of FG-HKUST-1, FG-HKUST-1 still exhibits the sieving effect of HKUST-1 for C1–C4 light hydrocarbons. More importantly, HKUST-1 is a polar material, while FG-HKUST-1 is a non-polar material. There is a dispersion force between the non-polar methane and ethane molecules and the non-polar FG-HKUST-1 material. That is, compared with the polar metal-organic framework HKUST-1 material, FG-HKUST-1 material has a stronger retention capacity for methane and ethane, thereby improving the separation of methane and ethane.

[0090] The FG-HKUST-1 material is a composite of FG material and HKUST-1 material. The synthesis of FG-HKUST-1 powder may include the following steps:

[0091] FG powder was placed in DMF (N,N-dimethylformamide) solvent, ultrasonically dispersed, and the supernatant was collected after standing.

[0092] A mixed solution was obtained by adding DMSO (dimethyl sulfoxide) solvent to Cu(NO3)2·3H2O powder and H3BTC (tristyric acid) powder and dispersing and dissolving them by ultrasonication.

[0093] The supernatant and the mixed solution were added to the CH3OH solution, and the mixture was stirred and centrifuged to obtain the lower solid layer.

[0094] The FG-HKUST-1 powder was obtained by washing and drying with CH3OH solution.

[0095] The preparation of the FG-HKUST-1 powder may include the following specific steps. It should be noted that the following is only an example to introduce the preparation of the FG-HKUST-1 powder, but the specific operation process, technology, and material selection are not limited to this and can be adapted accordingly, as follows:

[0096] (1) Add 15 mL of DMF and 0.2 g of FG powder to a glass bottle, sonicate for 30 min to obtain a dispersed multilayer fluorinated graphene suspension, let stand for 30 min, and collect the supernatant.

[0097] (2) Weigh 1.22g Cu(NO3)2·3H2O and 0.58g H3BTC into a beaker, add 5g DMSO solvent, and sonicate for 10min to dissolve them;

[0098] (3) Add 50 mL of CH3OH (methanol) and the collected supernatant to the conical flask, and slowly add the solution from the beaker in step (2) to the conical flask. Place a magnetic stir bar in the conical flask and stir for 24 h to obtain a blue-green solution.

[0099] (4) The blue-green solution obtained above was centrifuged using a high-speed centrifuge to separate the lower solid layer, which was washed three times with CH3OH and finally dried in an oven at 80℃ for 12 hours to obtain blue-green solid FG-HKUST-1 powder.

[0100] As an example, the steps for forming the FG-HKUST-1 stationary phase 700 may include:

[0101] FG-HKUST-1 powder is mixed with a solvent to form an FG-HKUST-1 solution;

[0102] The FG-HKUST-1 solution is injected into the closed microchannel 600 from the first port 310 and discharged through the second port to coat the closed microchannel 600 with FG-HKUST-1 material.

[0103] An aging process is performed to transform the FG-HKUST-1 material into an FG-HKUST-1 stationary phase 700 covering the inner surface 610 of the closed microchannel.

[0104] See Figure 8a and Figure 8b It should be noted that the following is only an example to illustrate the formation of the FG-HKUST-1 stationary phase 700, but the specific operating procedures, processes, and material selection are not limited to this, as detailed below:

[0105] Pretreatment before coating the microchromatographic column: Clean the closed microchannels of the microchromatographic column 5 with alcohol / acetone, etc., to remove some impurities inside the microchromatographic column 5.

[0106] Stationary phase coating: Weigh 20 mg of FG-HKUST-1 powder and add it to a pressure bottle 2 containing 5 mL of alcohol. Sonicate at room temperature for at least 10 min to obtain a stationary phase suspension 3 of FG-HKUST-1. Figure 8aConnect one end of pressure bottle 2 to high-pressure gas source 1, such as nitrogen, helium, or air (2.5 MPa). Connect the other end of pressure bottle 2 to one port of microchromatographic column 5 via adapter 4. Suspend the other end of microchromatographic column 5. Use high-pressure gas source 1 to force the stationary phase suspension 3 in pressure bottle 2 into the closed microchannels of microchromatographic column 5. After the liquid column has completely passed through the other port of microchromatographic column 5, continue for at least 30 minutes. Then, turn off high-pressure gas source 1, remove pressure bottle 2, and purge with 0.2 MPa nitrogen (or helium or air). Figure 8b Remove the residual liquid in the closed microchannel of microchromatographic column 5, and then age it at 120℃ for 5 hours to obtain microchromatographic column 5 with FG-HKUST-1 stationary phase coated on the inner wall.

[0107] As an example, the light hydrocarbons include C1 to C4 alkanes, especially methane-ethane.

[0108] Specifically, the prepared microchromatographic column exhibits the following separation effect when separating C1-C4 alkanes: Figure 11 Using this column, baseline separation of methane (20% v / v), ethane (0.2% v / v), propane (0.2% v / v), and butane (0.2% v / v) was achieved. While methane and ethane are inherently difficult to separate, and their concentrations differ significantly, the high retention time difference of 1.11 min allows for a methane-ethane resolution of up to 9.18. Therefore, this column effectively avoids the methane peak overshadowing the ethane peak in methane-ethane interactions with significant concentration differences. Furthermore, the ethane-propane resolution is 13.93, and the propane-butane resolution is 7.80, while quantitative analysis generally requires a resolution of at least 1.5. Therefore, this column can be used for the quantitative analysis of C1-C4 light hydrocarbons. In particular, the nonpolar FG-HKUST-1 stationary phase 700 improves the separation of nonpolar methane and ethane, two light hydrocarbons with low resolution, significant concentration differences, and similar properties.

[0109] As an example, the operating temperature of the microchromatographic column is below 300°C.

[0110] For details, please refer to Figure 10 The thermogravimetric analysis results of FG-HKUST-1 material are illustrated. As a stationary phase material, the safe operating temperature of FG-HKUST-1 should not exceed 300℃. This is mainly because when the temperature exceeds 300℃, H3BTC (tristyric acid) will be lost from the structure, causing the framework structure of FG-HKUST-1 to begin to collapse. Therefore, the operating temperature of the microchromatographic column is preferably below 300℃, such as 200℃ or 150℃.

[0111] See Figures 5-7This embodiment also provides a microchromatographic column, the microchromatographic column comprising:

[0112] Substrate 100;

[0113] Microchannel 300, located in the substrate 100, having a first port 310 and a second port (not shown);

[0114] Micropillars 400 are located in the microchannels 300. The micropillars 400 are arranged in n columns at intervals along the width direction of the microchannels 300 and in m rows at intervals along the extension direction of the microchannels 300, so as to form an n×m micropillar array.

[0115] A cover plate 500 is located on the surface of the substrate 100 and covers the microchannel 300, forming a closed microchannel 600.

[0116] FG-HKUST-1 stationary phase 700, wherein the FG-HKUST-1 stationary phase 700 covers the inner surface 610 of the closed microchannel, the material forming the FG-HKUST-1 stationary phase 700 includes FG and HKUST-1, the FG-HKUST-1 stationary phase 700 has a sieving effect, and the FG-HKUST-1 stationary phase 700 is a non-polar material.

[0117] As an example, the light hydrocarbons include C1 to C4 alkanes, especially methane-ethane.

[0118] As an example, the operating temperature of the microchromatographic column is below 300°C.

[0119] As an example, the micropillar 400 may include an elliptical micropillar or a circular micropillar. When the micropillar 400 is an elliptical micropillar, the major axis of the elliptical micropillar is parallel to the extension direction of the microchannel 300, and the minor axis of the elliptical micropillar is parallel to the width direction of the microchannel 300.

[0120] Specifically, in this embodiment, the micropillar 400 is preferably an elliptical micropillar. By using an n×m elliptical micropillar array located in the microchannel 300, the area of ​​the "quasi-zero flow velocity region" formed behind the micropillar can be greatly reduced, so that the FG-HKUST-1 stationary phase 700 coated on the micropillar 400 can be more uniform, and the flow velocity distribution inside the column can be uniform.

[0121] As an example, the cover plate 500 may include a glass cover plate, a silicon cover plate, or a ceramic cover plate. Preferably, the cover plate 500 and the substrate 100 are made of the same material to facilitate the formation of a uniform FG-HKUST-1 stationary phase 700 in the closed microchannel 600.

[0122] As an example, adjacent n columns of micropillars 400 are arranged at equal intervals along the width direction of the microchannel 300 to reduce process complexity; or, as needed, the n columns of micropillars can be arranged with different intervals along the width direction of the microchannel 300 to further make the flow velocity distribution within the column uniform and alleviate the problem of uneven carrier gas velocity.

[0123] As an example, along the width direction of the microchannel 300, the spacing s between adjacent n columns of micropillars 400 is smaller than the spacing S between the micropillars 400 located at the edge and the microchannel sidewall 110, i.e., S > s, so as to provide a uniform flow rate in the microchannel 300.

[0124] As an example, the morphology of the microchannel 300 includes one of the following: serpentine extension, zigzag extension, U-shaped extension, and spiral extension.

[0125] In summary, the microchromatographic column for light hydrocarbon separation and its preparation method of the present invention utilize FG and HKUST-1 to prepare the FG-HKUST-1 stationary phase of the microchromatographic column. The FG-HKUST-1 stationary phase is a non-polar material, which, in addition to its sieving effect on C1-C4 light hydrocarbons, further exhibits dispersion forces between the non-polar FG-HKUST-1 stationary phase and non-polar light hydrocarbons, such as non-polar methane and ethane. This allows the non-polar FG-HKUST-1 stationary phase to have a strong retention capacity for non-polar light hydrocarbons, thereby improving the separation degree of C1-C4 light hydrocarbons. This is especially beneficial for light hydrocarbons with low separation degree, significant concentration differences, and similar properties, such as methane and ethane. Therefore, the present invention can meet the requirements for qualitative and quantitative analysis and detection of light hydrocarbons.

[0126] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A microchromatographic column for the separation of light hydrocarbons, characterized in that, The microchromatographic column includes: Substrate; A microchannel located in the substrate, the microchannel having a first port and a second port; Micropillars are located in the microchannels, comprising n columns of micropillars spaced apart along the width of the microchannels and m rows of micropillars spaced apart along the extension of the microchannels, to form an n×m micropillar array. A cover plate, located on the surface of the substrate and covering the microchannel, forming a closed microchannel; The FG-HKUST-1 stationary phase covers the inner surface of the closed microchannels. The materials forming the FG-HKUST-1 stationary phase include FG and HKUST-1. The FG-HKUST-1 stationary phase has a sieving effect and is a non-polar material, which makes the non-polar FG-HKUST-1 stationary phase have a strong retention capacity for the non-polar light hydrocarbons, wherein the light hydrocarbons include C1 to C4 alkanes.

2. The microchromatographic column according to claim 1, characterized in that: The microchromatographic column operates at temperatures below 300°C.

3. The microchromatographic column according to claim 1, characterized in that: The micropillars include elliptical micropillars or circular micropillars. When the micropillar is an elliptical micropillar, the major axis of the elliptical micropillar is parallel to the extension direction of the microchannel, and the minor axis of the elliptical micropillar is parallel to the width direction of the microchannel.

4. The microchromatographic column according to claim 1, characterized in that: The cover plate includes a glass cover plate, a silicon cover plate, or a ceramic cover plate.

5. The microchromatographic column according to claim 1, characterized in that: The morphology of the microchannels includes one of the following: serpentine extension, zigzag extension, U-shaped extension, and spiral extension.

6. A method for preparing a microchromatographic column for the separation of light hydrocarbons, characterized in that, Includes the following steps: A substrate is provided, and a patterned mask layer is formed on the surface of the substrate; The substrate is etched based on the patterned mask layer to form microchannels and micropillars in the substrate. The microchannels have a first port and a second port. The micropillars are located in the microchannels and include n columns of the micropillars spaced apart along the width direction of the microchannels and m rows of the micropillars spaced apart along the extension direction of the microchannels to form an n×m micropillar array. A cover plate is provided and bonded to the surface of the substrate to cover the microchannel, forming a closed microchannel; An FG-HKUST-1 stationary phase is formed, which covers the inner surface of the closed microchannel. The material forming the FG-HKUST-1 stationary phase includes FG and HKUST-1. The FG-HKUST-1 stationary phase has a sieving effect and is a non-polar material, which makes the non-polar FG-HKUST-1 stationary phase have a strong retention capacity for the non-polar light hydrocarbons, wherein the light hydrocarbons include C1 to C4 alkanes.

7. The method for preparing a microchromatographic column according to claim 6, characterized in that, The steps for forming the FG-HKUST-1 stationary phase include: FG-HKUST-1 powder is mixed with a solvent to form an FG-HKUST-1 solution; The FG-HKUST-1 solution is injected into the closed microchannel from the first port and discharged through the second port to coat the closed microchannel with FG-HKUST-1 material. An aging process is performed to transform the FG-HKUST-1 material into an FG-HKUST-1 stationary phase covering the inner surface of the closed microchannels.

8. The method for preparing a microchromatographic column according to claim 7, characterized in that: The steps for preparing the FG-HKUST-1 powder include: FG powder was placed in DMF solvent, ultrasonically dispersed, and the supernatant was collected after standing. A mixed solution was obtained by adding DMSO solvent to Cu(NO3)2·3H2O powder and H3BTC powder and dispersing and dissolving them by ultrasonication. The supernatant and the mixed solution were added to the CH3OH solution, and the mixture was stirred and centrifuged to obtain the lower solid layer. The FG-HKUST-1 powder was obtained by washing and drying with CH3OH solution.

9. The method for preparing a microchromatographic column according to claim 6, characterized in that: After bonding the cover plate and before forming the FG-HKUST-1 stationary phase, a dicing step is also included.

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