Functional silica gel as well as preparation method and application thereof

Abstract

The invention provides functionalized silica gel and a preparation method and application thereof, the preparation method comprises the following steps: (1) activating silica gel with acid to obtain activated silica gel; (2) reacting an amino-containing silane coupling agent with the activated silica gel to obtain aminated silica gel; and (3) reacting the aminated silica gel with anhydride to obtain the functionalized silica gel. The functionalized silica gel disclosed by the invention can be used for separating 16 rare earth elements, and has relatively high separation selectivity and repeatability.

Description

Technical Field

[0001] This invention relates to the field of rare earth separation technology, and in particular to a functionalized silica gel, its preparation method, and its application. Background Technology

[0002] Rare earth elements are a core strategic resource for my country, and high-purity rare earth elements are key raw materials for developing cutting-edge technologies such as next-generation information technology, new energy, and aerospace. However, due to the high similarity in physical and chemical properties among rare earth elements, traditional separation methods lack selectivity, and the presence of various associated impurities increases the difficulty of separation and purification. In addition, high-end applications have extremely stringent requirements for the purity of rare earth elements. Therefore, the separation and preparation of high-purity rare earth elements still faces enormous challenges.

[0003] Chromatographic separation offers advantages such as speed, efficiency, simplicity of operation, and high product purity, making it crucial for rare earth separation and the preparation of high-purity rare earths. As the core of chromatographic separation, the packing material's surface functional design, pore size distribution, and mechanical strength directly influence the separation efficiency of rare earths. Therefore, optimizing packing material performance is a key technological pathway to achieving efficient separation and purification of rare earth metals.

[0004] CN113966318A discloses compounds, separation methods, and applications for the chromatographic separation of rare earth elements and S, P, and D metals. This invention responds to even very small differences in the ionic radius of metals by utilizing the significant differences in the polarity of chelates formed by rare earth elements and chelating agents. Due to the different polarities, the chelates can be separated by conventional normal-phase or reversed-phase chromatography, achieving the chromatographic separation of Gd, Tb, and Dy chelates.

[0005] CN117778769A discloses a method for separating adjacent rare earth elements. First, sulfonic acid microspheres are fully soaked and swollen in a nitric acid aqueous solution and then wet-packed into a chromatographic column. Rare earth element raw materials are dissolved in the nitric acid aqueous solution to obtain the raw material solution to be separated. The raw material solution is then fed into the upper part of the chromatographic column and washed with water. The mobile phase is then fed into the chromatographic column, and the separated adjacent rare earth elements are obtained at the column outlet. This method achieves rapid separation of rare earth elements under acidic conditions through pressurized ion exchange technology, with a separation time of less than 5 hours, a recovery rate of 90%, and a purity of 99%.

[0006] However, current methods still face challenges such as long separation times and difficulties in baseline separation when simultaneously separating all rare earth elements. Therefore, developing a high-efficiency, high-capacity, and highly selective functionalized silica gel is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a functionalized silica gel, its preparation method, and its applications. The functionalized silica gel exhibits good separation selectivity and repeatability in the separation of rare earth elements and can be used for the large-scale preparation of high-purity rare earth elements.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing functionalized silicone, the method comprising the following steps:

[0010] (1) Activate silica gel by acid treatment to obtain activated silica gel;

[0011] (2) React the aminosilane coupling agent with the activated silica gel to obtain amino-modified silica gel;

[0012] (3) The amino-modified silica gel is reacted with an acid anhydride to obtain the functionalized silica gel.

[0013] In this invention, silica gel is first activated with acid, then the activated silica gel is reacted with an amino group in a silane coupling agent to obtain aminated silica gel. Finally, the aminated silica gel is reacted with an acid anhydride to give the silica gel surface a carboxyl group, thus obtaining the functionalized silica gel, which can be used for the separation of 16 rare earth elements and has good separation selectivity and repeatability.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0015] Preferably, the acid includes hydrochloric acid.

[0016] Preferably, the aminosilane-containing coupling agent comprises 3-aminopropyltriethoxysilane.

[0017] Preferably, the acid anhydride includes 1,2,4-benzenetricarboxylic anhydride.

[0018] Preferably, the activation treatment is performed at room temperature.

[0019] Preferably, the activation treatment time is 6-12 hours, for example, 7 hours, 8 hours, 9 hours, 10 hours or 11 hours.

[0020] Preferably, the activation treatment further includes washing and drying.

[0021] Preferably, the drying temperature is 40-90℃, for example, it can be 50℃, 60℃, 70℃ or 80℃.

[0022] Preferably, the drying time is 12-24 hours, for example, 14 hours, 16 hours, 18 hours, 20 hours or 22 hours.

[0023] Preferably, the mass ratio of the aminosilane coupling agent to the activated silica gel is (1.4-2.4):1, for example, it can be 1.6:1, 1.8:1, 2:1 or 2.2:1, etc.

[0024] Preferably, in step (2), the reaction temperature is 80-120℃, for example, it can be 85℃, 90℃, 95℃, 100℃, 105℃, 110℃ or 115℃, etc.

[0025] Preferably, in step (2), the reaction time is 24-48h, for example, 28h, 32h, 36h, 40h or 44h.

[0026] Preferably, in step (2), the reaction is carried out in a solvent.

[0027] Preferably, the solvent includes toluene or N,N-dimethylformamide.

[0028] Preferably, the mass ratio of the aminated silica gel to the acid anhydride is 1:(0.5-1), for example, it can be 1:0.6, 1:0.7, 1:0.8 or 1:0.9, etc.

[0029] Preferably, in step (3), the reaction temperature is 80-120℃, for example, it can be 85℃, 90℃, 95℃, 100℃, 105℃, 110℃ or 115℃, etc.

[0030] Preferably, in step (3), the reaction time is 24-48h, for example, 28h, 32h, 36h, 40h or 44h.

[0031] Preferably, in step (3), the reaction is carried out in a solvent.

[0032] Preferably, the solvent includes N,N-dimethylformamide or toluene.

[0033] Secondly, the present invention provides a functionalized silicone prepared by the method for preparing functionalized silicone as described in the first aspect.

[0034] Thirdly, the present invention provides an application of functionalized silica gel as described in the second aspect in the separation of rare earth elements.

[0035] Fourthly, the present invention provides a method for separating rare earth elements, which uses ion exchange chromatography to separate rare earth elements, wherein the stationary phase of the ion exchange chromatography includes the functionalized silica gel described in the second aspect.

[0036] Preferably, the detection wavelength of the ion exchange chromatography is 655-660 nm, for example, it can be 656 nm, 657 nm, 658 nm or 659 nm.

[0037] Preferably, the column temperature of the ion exchange chromatography is 25-45℃, for example, it can be 26℃, 30℃, 34℃, 38℃ or 42℃, etc.

[0038] Preferably, the flow rate of the ion exchange chromatography is 0.8-1.2 mL / min, for example, it can be 0.9 mL / min, 1.0 mL / min or 1.1 mL / min.

[0039] Preferably, the mobile phase of the ion exchange chromatography includes phase A and phase B.

[0040] Preferably, phase A comprises water.

[0041] Preferably, phase B comprises an aqueous solution of α-hydroxyisobutyric acid.

[0042] Preferably, the concentration of the α-hydroxyisobutyric acid aqueous solution is 100-400mM, for example, it can be 150mM, 200mM, 250mM, 300mM or 350mM.

[0043] Preferably, the pH of the α-hydroxyisobutyric acid aqueous solution is 2.5-4.5, for example, it can be 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2 or 4.4.

[0044] Preferably, the flow rate of the post-column derivatization solution in the ion exchange chromatography is 0.4-0.8 mL / min, for example, 0.5 mL / min, 0.6 mL / min or 0.7 mL / min.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] In this invention, silica gel is first activated with acid, then the activated silica gel is reacted with the amino group in the silane coupling agent to obtain aminated silica gel. Finally, the aminated silica gel is reacted with acid anhydride to give the silica gel surface a carboxyl group, thus obtaining the functionalized silica gel. It can separate 16 rare earth elements within 55 minutes and has high separation selectivity and repeatability. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the preparation process of the functionalized silicone of the present invention;

[0048] Figure 2 Fourier transform infrared spectrum of the functionalized silicone prepared in Example 1;

[0049] Figure 3 The X-ray photoelectron spectroscopy (XPS) spectra of the functionalized silicone prepared in Example 1 are shown in (a) and (b) respectively. (a) is the full XPS spectrum of the functionalized silicone; (b) is the high-resolution spectrum of C element in the functionalized silicone.

[0050] Figure 4 The chromatograms of the separation of 16 rare earth elements by the functionalized silica gel prepared in Example 1 are shown.

[0051] Figure 5 The chromatograms of the separation of 16 rare earth elements by the functionalized silica gel prepared in Example 2 are shown.

[0052] Figure 6 The results of stability tests on the functionalized silica column prepared in Example 2;

[0053] Figure 7 The chromatograms of the separation of 16 rare earth elements by the functionalized silica gel prepared in Example 3 are shown.

[0054] Figure 8 The chromatograms of the separation of 16 rare earth elements by the functionalized silica gel prepared in Example 4 are shown.

[0055] Figure 9 The chromatograms of the separation of 16 rare earth elements by the functionalized silica gel prepared for Comparative Example 1. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] Example 1

[0058] (1) Take concentrated hydrochloric acid (36%, 20mL) and silica gel (10g) and treat at room temperature for 8h. Wash with water until neutral to obtain activated silica gel (Sil);

[0059] (2) Activated silica gel (5.0 g) and toluene (50 mL) were placed in a 100 mL three-necked round-bottom flask and ultrasonically dispersed. Then, 3-aminopropyltriethoxysilane (7.5 g) was added. Under mechanical stirring, the temperature was raised to 115 °C and the reaction was refluxed for 24 h. After the reaction was completed, the product was washed with water and ethanol in sequence and dried under vacuum at 60 °C for 24 h to obtain amino-modified silica gel (Sil-NH2).

[0060] (3) Aminated silica gel (4.5 g) and 1,2,4-benzenetricarboxylic anhydride (3.0 g) were placed in a 100 mL three-necked round-bottom flask, and N,N-dimethylformamide (50 mL) was added. The mixture was ultrasonically dispersed and mechanically stirred at 110 °C for 24 h. After the reaction was completed, the product was washed with acetone, ethanol and water respectively, and dried under vacuum at 60 °C for 24 h to obtain the functionalized silica gel (Sil-TMA-1).

[0061] Figure 1 This is a schematic diagram of the preparation process of functionalized silicone.

[0062] Structural characterization of functionalized silicone:

[0063] A. The Fourier transform infrared spectrum of Sil-TMA-1 is as follows: Figure 2 As shown, by comparing the infrared spectra of Sil, Sil-NH2, and Sil-TMA-1, it can be found that Sil-NH2 has a peak value at 2936 cm⁻¹. -1 The CH bond appears at 1560cm. -1 The presence of an infrared characteristic peak for NH bonds at 1719 cm⁻¹ indicates the successful preparation of Sil-NH₂; Sil-TMA-1 shows an infrared characteristic peak for NH bonds at 1719 cm⁻¹. -1 The presence of a new characteristic peak for a C=O double bond indicates that the carboxyl group has been successfully modified onto the silica gel surface.

[0064] B. Perform XPS analysis on Sil-TMA-1, and analyze the full spectrum ( Figure 3 The characteristic peaks at 102.8 eV, 284.8 eV, 400.4 eV, and 532.8 eV in (a) are attributed to Si 2p, N 1s, C 1s, and O 1s, respectively. High-resolution C 1s spectrum ( Figure 3 In b), the peaks at 284.8 eV and 288.5 eV are attributed to CC and OC=O bonds, respectively, confirming the successful introduction of carboxylic acid groups onto the silica gel surface.

[0065] A Sil-TMA-1 column was prepared by packing Sil-TMA-1 into a 4.6 × 150 mm stainless steel column. The chromatographic conditions were as follows: column temperature 25℃, UV-Vis detector wavelength 658 nm, mobile phase flow rate 1.0 mL / min, using α-hydroxyisobutyric acid aqueous solution (α-HIBA) as the mobile phase. Rare earth elements were detected by post-column derivatization at a flow rate of 0.6 mL / min. Elution was performed using the gradient program shown in Table 1. The separation performance of this column for 16 rare earth elements was obtained as follows: Figure 4 As shown, the separation of 16 rare earth elements was achieved.

[0066] Table 1

[0067]

[0068] Example 2

[0069] (1) Take concentrated hydrochloric acid (36%, 20mL) and silica gel (10g) and treat at room temperature for 12h. Wash with water until neutral to obtain activated silica gel (Sil);

[0070] (2) Activated silica gel (5.0 g) and toluene (50 mL) were placed in a 100 mL three-necked round-bottom flask and ultrasonically dispersed. Then, 3-aminopropyltriethoxysilane (7.5 g) was added. Under mechanical stirring, the temperature was raised to 115 °C and the reaction was refluxed for 24 h. After the reaction was completed, the product was washed with water and ethanol in sequence and dried under vacuum at 60 °C for 24 h to obtain amino-modified silica gel (Sil-NH2).

[0071] (3) Aminated silica gel (4.5 g) and 1,2,4-benzenetricarboxylic anhydride (3.0 g) were placed in a 100 mL three-necked round-bottom flask, and N,N-dimethylformamide (50 mL) was added. The mixture was ultrasonically dispersed and mechanically stirred at 110 °C for 48 h. After the reaction was completed, the product was washed with acetone, ethanol and water respectively, and dried under vacuum at 60 °C for 24 h to obtain the functionalized silica gel (Sil-TMA-2).

[0072] A Sil-TMA-2 column was prepared by packing Sil-TMA-2 into a 4.6 × 150 mm stainless steel column. The chromatographic conditions were as follows: column temperature 25℃, UV-Vis detector wavelength 658 nm, mobile phase flow rate 1.0 mL / min, using α-HIBA as the mobile phase. Rare earth elements were detected by post-column derivatization at a flow rate of 0.6 mL / min. Elution was performed using the gradient program shown in Table 1. The resulting chromatograms show the separation of 16 rare earth elements using this column. Figure 5 As shown in the figure, the elution order of the corresponding analytes is as follows: lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), yttrium (Y), dysprosium (Dy), scandium (Sc), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), and lanthanum (La). The results show that all 16 rare earth elements were baseline separated within 55 min, indicating that the stationary phase has a good separation effect on the 16 rare earth elements.

[0073] To test the stability of the Sil-TMA-2 column, nine repeated tests were conducted using 16 rare earth elements as analytes. The test results are as follows: Figure 6 As shown, this indicates that the chromatographic column exhibits good repeatability.

[0074] Example 3

[0075] (1) Take concentrated hydrochloric acid (36%, 20mL) and silica gel (10g) and treat at room temperature for 12h. Wash with water until neutral to obtain activated silica gel (Sil);

[0076] (2) Activated silica gel (5.0 g) and toluene (50 mL) were placed in a 100 mL three-necked round-bottom flask and ultrasonically dispersed. Then, 3-aminopropyltriethoxysilane (7.5 g) was added. Under mechanical stirring, the temperature was raised to 120 °C and the reaction was refluxed for 48 h. After the reaction was completed, the product was washed with water and ethanol in sequence and dried under vacuum at 60 °C for 24 h to obtain amino-modified silica gel (Sil-NH2).

[0077] (3) Aminated silica gel (4.5 g) and 1,2,4-benzenetricarboxylic anhydride (3.5 g) were placed in a 100 mL three-necked round-bottom flask, and N,N-dimethylformamide (50 mL) was added. The mixture was ultrasonically dispersed and mechanically stirred at 120 °C for 48 h. After the reaction was completed, the product was washed with acetone, ethanol, and water, respectively, and then vacuum dried at 70 °C for 18 h to obtain the functionalized silica gel (Sil-TMA-3). The stationary phase achieved the following separation effect: Figure 7 As shown, it can separate 16 rare earth elements.

[0078] Example 4

[0079] (1) Take concentrated hydrochloric acid (36%, 20mL) and silica gel (10g) and treat at room temperature for 9h. Wash with water until neutral to obtain activated silica gel (Sil);

[0080] (2) Place activated silica gel (5.0 g) and toluene (50 mL) in a 100 mL three-necked round-bottom flask, disperse evenly by ultrasonication, add 7.5 g of 3-aminopropyltriethoxysilane, heat to 120 °C under mechanical stirring, reflux for 48 h, wash the product with water and ethanol in sequence after the reaction is completed, and dry under vacuum at 60 °C for 24 h to obtain amino-modified silica gel (Sil-NH2);

[0081] (3) Aminated silica gel (4.5 g) and 1,2,4-benzenetricarboxylic anhydride (4.5 g) were placed in a 100 mL three-necked round-bottom flask, and N,N-dimethylformamide (50 mL) was added. The mixture was ultrasonically dispersed and mechanically stirred at 120 °C for 48 h. After the reaction was completed, the product was washed with acetone, ethanol, and water, respectively, and then vacuum dried at 70 °C for 18 h to obtain the functionalized silica gel (Sil-TMA-4). The stationary phase achieved the following separation effect: Figure 8 As shown, it can separate 16 rare earth elements.

[0082] Comparative Example 1

[0083] (1) Take concentrated hydrochloric acid (36%, 20mL) and silica gel (10g) and treat at room temperature for 6h. Wash with water until neutral to obtain activated silica gel (Sil);

[0084] (2) Activated silica gel (5.0 g) and toluene (50 mL) were placed in a 100 mL three-necked round-bottom flask and ultrasonically dispersed. Then, 3-aminopropyltriethoxysilane (7.5 g) was added. Under mechanical stirring, the temperature was raised to 120 °C and the reaction was refluxed for 48 h. After the reaction was completed, the product was washed with water and ethanol in sequence and dried under vacuum at 60 °C for 24 h to obtain amino-modified silica gel (Sil-NH2).

[0085] (3) Aminated silica gel (4.5 g) and maleic anhydride (2.5 g) were placed in a 100 mL three-necked round-bottom flask, and N,N-dimethylformamide (50 mL) was added. The mixture was ultrasonically dispersed and mechanically stirred at 110 °C for 48 h. After the reaction was completed, the product was washed with acetone, ethanol, and water, respectively, and then vacuum dried at 70 °C for 18 h to obtain functionalized silica gel (Sil-MA). The separation effect is as follows: Figure 9 As shown, the separation peaks all exhibited tailing, and baseline separation of the 16 rare earth elements could not be achieved.

[0086] In summary, this invention first introduces amino groups onto the surface of silica gel using an amino-containing silane coupling agent to obtain Sil-NH2, and then introduces carboxylic acid groups through an amidation reaction between Sil-NH2 and acid anhydrides, thus preparing carboxyl-functionalized silica gel Sil-TMA. This product can be used as a chromatographic stationary phase to achieve rapid separation of 16 rare earth elements. This invention has good practical application value and can be used for the rapid separation and large-scale preparation of high-purity rare earth elements.

[0087] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing functionalized silicone, characterized in that, The preparation method includes the following steps: (1) Activate silica gel by acid treatment to obtain activated silica gel; (2) React the aminosilane coupling agent with the activated silica gel to obtain amino-modified silica gel; (3) The amino-modified silica gel is reacted with an acid anhydride to obtain the functionalized silica gel.

2. The preparation method according to claim 1, characterized in that, The acid includes hydrochloric acid; Preferably, the aminosilane-containing coupling agent comprises 3-aminopropyltriethoxysilane; Preferably, the acid anhydride includes 1,2,4-benzenetricarboxylic anhydride.

3. The preparation method according to claim 1 or 2, characterized in that, The activation treatment was performed at room temperature. Preferably, the activation treatment time is 6-12 hours; Preferably, the activation treatment further includes washing and drying; Preferably, the drying temperature is 50-90°C; Preferably, the drying time is 12-24 hours.

4. The preparation method according to any one of claims 1-3, characterized in that, The mass ratio of the aminosilane coupling agent to the activated silica gel is (1.4-2.4):1; Preferably, in step (2), the reaction temperature is 80-120°C; Preferably, in step (2), the reaction time is 24-48 hours.

5. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the reaction is carried out in a solvent; Preferably, the solvent includes toluene or N,N-dimethylformamide.

6. The preparation method according to any one of claims 1-5, characterized in that, The mass ratio of the aminated silica gel to the acid anhydride is 1:(0.5-1); Preferably, in step (3), the reaction temperature is 80-120°C; Preferably, in step (3), the reaction time is 24-48 hours; Preferably, in step (3), the reaction is carried out in a solvent; Preferably, the solvent includes N,N-dimethylformamide or toluene.

7. A functionalized silicone prepared by the method of any one of claims 1-6.

8. The application of the functionalized silica gel as described in claim 7 in the separation of rare earth elements.

9. A method for separating rare earth elements, characterized in that, Rare earth elements are separated by ion exchange chromatography, wherein the stationary phase of the ion exchange chromatography comprises the functionalized silica gel as described in claim 7.

10. The method according to claim 9, characterized in that, The detection wavelength of the ion exchange chromatography is 655-660 nm; Preferably, the column temperature of the ion exchange chromatography is 25-45℃; Preferably, the flow rate of the ion exchange chromatography is 0.8-1.2 mL / min; Preferably, the mobile phase of the ion exchange chromatography includes phase A and phase B; Preferably, phase A comprises water; Preferably, phase B comprises an aqueous solution of α-hydroxyisobutyric acid; Preferably, the concentration of the α-hydroxyisobutyric acid aqueous solution is 100-400 mM; Preferably, the pH of the α-hydroxyisobutyric acid aqueous solution is 2.5-4.5; Preferably, the flow rate of the post-column derivatization solution in the ion exchange chromatography is 0.4-0.8 mL / min.

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