Silica gel matrix c18 bonded adsorbent packing and one-step process for its preparation

Abstract

The application discloses a one-step preparation process of a silica gel matrix C18 bonded adsorption filler, which comprises the following steps: dispersing a silica gel matrix in an organic solvent, adding a C18 alkyl silane reagent, performing a bonding reaction at a preset temperature interval, and generating a reaction mixture containing an acidic byproduct; after the bonding reaction is completed, no intermediate washing and intermediate drying are performed, but an inert gas is introduced into the same reaction container to remove the acidic byproduct from the reaction container through purging; then, a chlorosilane capping reagent is added into the same reaction container to perform a capping reaction, and after the capping reaction is completed, the silica gel matrix C18 bonded adsorption filler is obtained through washing and drying. The application removes the acidic byproduct generated in the bonding reaction through inert gas purging, so that the bonding reaction and the capping reaction can be continuously performed in the same reaction container, intermediate washing, drying and intermediate transfer steps are reduced, the preparation process is shortened, solvent and energy consumption are reduced, and the batch stability of the product is improved.

Description

Technical Field

[0001] This invention relates to the field of adsorption material preparation technology, and in particular to a silica matrix C18 bonded adsorption filler and its one-step preparation process. Background Technology

[0002] C18 bonded adsorption packings based on silica gel are a commonly used type of reversed-phase adsorption material. They typically use porous silica gel as the matrix, and the silanol groups on the silica gel surface bond with C18 alkylsilanizing reagents, introducing octadecyl hydrophobic segments onto the silica gel surface, thus forming a packing material with hydrophobic adsorption properties. This type of packing material is widely used in high-performance liquid chromatography (HPLC) separation, solid-phase extraction sample pretreatment, and target analyte enrichment analysis.

[0003] In the preparation of C18-bonded adsorption packing materials on a silica matrix, simply completing the C18 bonding reaction is usually insufficient to completely consume the active silanol groups on the silica surface. Residual silanol groups may affect the separation selectivity, adsorption stability, and reproducibility of the packing material. Therefore, existing preparation processes typically involve a capping reaction after the C18 bonding reaction, specifically treating the residual silanol groups on the silica matrix surface with a chlorosilane capping agent to reduce the adverse effects of residual silanol groups on subsequent application performance.

[0004] Existing silica-based C18-bonded adsorption packing materials are typically prepared using a stepwise process. This process generally involves first dispersing the silica matrix in an organic solvent, then adding a C18 alkylsilanizing agent to initiate a C18 bonding reaction. After the bonding reaction is complete, the reaction product is washed and dried to obtain a C18-bonded silica intermediate. This intermediate is then reintroduced into the reaction vessel, and an organic solvent and a chlorosilane end-capping agent are added again to initiate the end-capping reaction. After the end-capping reaction is complete, the material is washed and dried again to finally obtain the silica-based C18-bonded adsorption packing material.

[0005] While the stepwise preparation process described above can obtain C18-bonded adsorption fillers on a silica matrix, its process flow is lengthy. Especially between the C18 bonding reaction and the end-capping reaction, the intermediate products require multiple washing and drying processes, increasing solvent consumption and drying energy consumption, and extending the production cycle. For mass production, the intermediate washing, drying, and refeeding processes increase manual operation, raising the complexity of process control.

[0006] Meanwhile, intermediate products may be affected by external environment, operating conditions, and material contact processes during washing, drying, transfer, and redispersing. For example, impurities may be introduced into the intermediate products during transfer or storage; the uniformity of dispersion may be affected when the dried intermediate products are redispersed; repeated washing and drying may also adversely disturb the formed C18 bonded layer. These factors may all affect the consistency of subsequent end-capping reactions and the batch stability of the final filler.

[0007] Therefore, developing a silica matrix C18 bonded adsorption filler preparation process that can simplify process steps, reduce production costs, and at the same time ensure product quality comparable to existing two-step methods has become an urgent technical problem to be solved in this field. Summary of the Invention

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0009] This invention provides a one-step preparation process for C18 bonded adsorption fillers in a silica matrix, comprising the following steps: (a) Add silica gel matrix and organic solvent to the reaction vessel respectively, so that the silica gel matrix is ​​dispersed in the organic solvent; (b) A C18 alkylsilanizing agent is added to the reaction vessel to carry out a bonding reaction; (c) After the bonding reaction is completed, without intermediate washing and drying, an inert gas is directly introduced into the reaction vessel to purge the acidic byproducts generated by the bonding reaction. (d) After purging, add a chlorosilane end-capping agent to the reaction vessel to carry out the end-capping reaction; (e) After the end-capping reaction is completed, the silica matrix C18 bonded adsorption packing is obtained by washing and drying.

[0010] Furthermore, in step (a), the silica matrix is ​​a spherical porous silica. Spherical porous silica provides surface silanol groups and a pore structure suitable for C18 alkyl bonding.

[0011] Further, in step (a), the organic solvent is toluene. Toluene, as an organic solvent, facilitates the contact and dispersion of the C18 alkylsilanizing agent and the silica matrix in the reaction system.

[0012] Further, in step (b), the bonding reaction is carried out at a preset temperature range of 80-110°C for a reaction time of 12-24 hours; the C18 alkyl silanizing agent is octadecyltrichlorosilane. By controlling the bonding reaction temperature and reaction time, the C18 alkyl silanizing agent can fully react with the silanol groups on the surface of the silica matrix, thereby forming a C18 alkyl bonding layer on the surface of the silica matrix.

[0013] Furthermore, in steps (c) and (d), the temperature inside the reaction vessel is maintained within the preset temperature range. Thus, during the removal of acidic byproducts and subsequent end-capping reactions, the reaction system does not need to undergo cooling, discharging, washing, drying, refeeding, and reheating processes, which helps maintain the continuity of the reaction system.

[0014] Furthermore, in step (c), the inert gas is introduced for 1-3 hours at a rate of 0.5-2 L / min. By controlling the inert gas introduction time and rate, acidic byproducts can be removed while avoiding insufficient removal due to weak gas introduction, and also avoiding excessive disturbance to the reaction system due to strong gas introduction.

[0015] Furthermore, in step (c), the inert gas is introduced using a continuous purging method. Continuous purging ensures thorough removal of byproducts.

[0016] Furthermore, in both steps (b) and (d), an inert gas is introduced into the reaction vessel for reaction protection. Inert gas protection reduces interference from external factors such as moisture or oxygen on the silanization reaction process, thereby improving the stability of the reaction.

[0017] Further, in step (d), the reaction time for the end-capping reaction is 4-8 hours; the chlorosilane end-capping reagent is selected from at least one of trimethylchlorosilane, dimethyldichlorosilane, or diphenylmethylchlorosilane. This reaction time setting allows the chlorosilane end-capping reagent to fully react with the residual silanol groups on the silica matrix surface, thereby reducing the impact of residual silanol groups on the adsorption performance and stability of the filler. The aforementioned chlorosilane end-capping reagent can react with the residual silanol groups on the silica matrix surface, thus completing the end-capping treatment of the residual silanol groups.

[0018] A second objective of this invention is to provide a silica matrix C18 bonded adsorption filler.

[0019] A silica-based C18 bonded adsorption filler is prepared using the above-described preparation process.

[0020] In summary, the present invention has the following beneficial effects: 1. In this invention, after the C18 bonding reaction is completed, intermediate washing and drying are not performed. Instead, an inert gas is directly introduced into the same reaction vessel to purge the acidic byproducts away from the reaction vessel. This eliminates the intermediate washing, drying, and intermediate refeeding steps between the C18 bonding reaction and the end-capping reaction in the traditional two-step method, allowing the C18 bonding reaction, byproduct removal, and end-capping reaction to proceed continuously within the same reaction vessel.

[0021] 2. This invention removes acidic byproducts generated during the bonding reaction by purging with an inert gas, allowing the subsequent chlorosilane end-capping reagent to be directly added to the same reaction vessel for the end-capping reaction. This method does not simply omit intermediate washing and drying; rather, it establishes a suitable reaction environment for the subsequent end-capping reaction by removing the acidic byproducts with gas, thus ensuring the feasibility of a one-step continuous preparation process.

[0022] 3. This invention reduces intermediate washing, intermediate drying and intermediate transfer processes, which helps to reduce washing solvent consumption, drying energy consumption, and shorten the preparation cycle, and reduces the risk of introducing impurities or causing batch fluctuations during the transfer, storage and redispersing of intermediate products.

[0023] 4. By controlling the preset temperature range, bonding reaction time, inert gas introduction time, inert gas introduction rate, and end-capping reaction time, this invention connects the acidic byproduct removal process with the subsequent end-capping reaction process, which is beneficial to maintaining the stability of the C18 bond layer and improving the consistency of the end-capping reaction. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the following embodiments are only for illustrating the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Conventional adjustments made by those skilled in the art to the types of raw materials, the form of the reaction vessel, the reaction scale, the stirring method, the washing method, or the drying method without departing from the technical concept of the present invention should all fall within the scope of protection of the present invention.

[0026] like Figure 1 As shown, this invention provides a one-step preparation process for C18 bonded adsorption packing material based on silica gel. The core of this process is as follows: after the C18 alkylsilanizing reagent completes the bonding reaction with the silica gel matrix, instead of performing intermediate washing and drying on the reaction system, an inert gas is directly introduced into the same reaction vessel. This inert gas carries away the acidic byproducts generated during the bonding reaction through purging. Subsequently, after the acidic byproducts are removed, a chlorosilane end-capping reagent is directly added to the same reaction vessel for end-capping reaction. Finally, after washing and drying, the C18 bonded adsorption packing material based on silica gel is obtained.

[0027] In this invention, the silica matrix can be high-purity spherical porous silica. The surface of the high-purity spherical porous silica has silanol groups, which can undergo a bonding reaction with C18 alkylsilanizing reagents, thereby forming C18 hydrophobic segments on the surface of the silica matrix. The organic solvent can be toluene, used to disperse the silica matrix and provide a suitable organic reaction environment for the C18 alkylsilanization reaction.

[0028] The C18 alkylsilanizing agent is an octadecylchlorosilane, preferably octadecyltrichlorosilane. When the octadecylchlorosilane reacts with the silanol groups on the surface of the silica matrix, a reaction mixture containing acidic byproducts is generated. These acidic byproducts may include HCl byproducts. If too much of this acidic byproduct remains in the reaction system, it may affect the subsequent end-capping reaction between the chlorosilane end-capping agent and the residual silanol groups on the silica matrix surface. Therefore, this invention uses an inert gas purging method to remove the acidic byproducts from the reaction vessel, allowing the subsequent end-capping reaction to continue within the same reaction vessel. If the silanizing agent used is octadecyltrimethoxysilane, octadecyltriethoxysilane, etc., the purging is to remove the byproduct methanol, and residual methanol can also affect the second-step end-capping reaction. Therefore, the silanizing agent used in this invention is octadecyltrichlorosilane. The inert gas can be one or a mixture of nitrogen and argon. The inert gas serves two purposes in this invention: first, as a purge gas after the bonding reaction to carry away acidic byproducts from the reaction vessel; second, as a protective gas during the bonding and end-capping reactions to reduce interference from external moisture or oxygen on the silanization process.

[0029] The chlorosilane end-capping reagent can be selected from at least one of trimethylchlorosilane, dimethyldichlorosilane, or diphenylmethylchlorosilane. This type of chlorosilane end-capping reagent can react with residual silanol groups on the surface of the silica matrix, thereby reducing the impact of residual silanol groups on adsorption selectivity and stability.

[0030] In this invention, the preset temperature range can be 80-110℃. Within this temperature range, the C18 alkylsilanizing agent can undergo a bonding reaction with the silanol groups on the surface of the silica matrix, which also facilitates the subsequent purging and removal of acidic byproducts and the continuous progress of the end-capping reaction. The bonding reaction can take 12-24 hours. The inert gas can be introduced for 1-3 hours at a rate of 0.5-2 L / min. The end-capping reaction can take 4-8 hours.

[0031] During steps (c) and (d), the temperature inside the reaction vessel can be maintained within the preset temperature range. This setting eliminates the need for cooling, discharging, washing, drying, refeeding, and reheating processes after the bonding reaction is complete, ensuring the continuity of the process.

[0032] Example 1:

[0033] This embodiment provides a one-step preparation process for C18 bonded adsorption fillers in a silica matrix, specifically including the following steps: (1) Material preparation.

[0034] Take 100g of high-purity spherical porous silica gel, 500mL of toluene, 20g of octadecyltrichlorosilane, 10g of trimethylchlorosilane, and nitrogen.

[0035] The high-purity spherical porous silica gel has a particle size of 5 μm and a specific surface area of ​​300 m² / g; toluene is used as an organic solvent; octadecyltrichlorosilane is used as a C18 alkylsilanizing agent; trimethylchlorosilane is used as a chlorosilane end-capping agent; and nitrogen is used as an inert gas.

[0036] (2) Silica matrix dispersion.

[0037] 100g of high-purity spherical porous silica gel was added to a three-necked reactor, and then 500mL of toluene was added to the reactor. The mixture was then magnetically stirred to ensure that the high-purity spherical porous silica gel was uniformly dispersed in the toluene.

[0038] In this step, toluene is used to form an organic reaction system, allowing the silica matrix to come into full contact with the subsequently added octadecyltrichlorosilane.

[0039] (3) C18 bonding reaction.

[0040] 20g of octadecyltrichlorosilane was added to a three-necked reactor, and a small amount of nitrogen gas was introduced into the reactor for reaction protection. Subsequently, the reaction temperature was controlled at 105℃, and the reaction was carried out for 24h under stirring to allow the octadecyltrichlorosilane to bond with the silanol groups on the surface of high-purity spherical porous silica gel.

[0041] In this reaction, octadecyltrichlorosilane reacts with the silanol groups on the surface of the silica matrix to form a C18 alkyl bonded layer on the surface of the silica matrix, and generates a reaction mixture containing HCl acidic byproducts.

[0042] (4) Removal of acidic byproducts.

[0043] After the C18 bonding reaction is completed, the products in the reaction system are not subjected to intermediate washing and drying, nor are the reaction products removed from the three-necked reactor.

[0044] Maintain the temperature inside the three-necked reactor at 105℃, and continuously purge the reactor with nitrogen gas at a rate of 1L / min for 2 hours. The continuous purging action of nitrogen gas will remove the residual acidic HCl byproducts from the reaction vessel.

[0045] In this step, nitrogen purging replaces the intermediate washing and drying processes following the C18 bonding reaction in traditional processes. By directly purging acidic byproducts within the same reaction vessel, the processes of removing, washing, drying, refeeding, and redispersing reaction products can be reduced.

[0046] (5) End-capping reaction.

[0047] After removing the acidic byproducts, 10g of trimethylchlorosilane was added directly to the same three-necked reactor. The reaction temperature was maintained at 105℃, and the mixture was stirred for 6 hours to allow the trimethylchlorosilane to undergo a capping reaction with the silanol groups remaining on the surface of the silica matrix.

[0048] In this step, since the acidic HCl byproducts have been removed from the reaction vessel by nitrogen purging in the previous step, trimethylchlorosilane can directly undergo the end-capping reaction in the same reaction system without having to wash, dry, and reintroduce the C18 bonded silica intermediate into the reaction system.

[0049] (6) Finished product processing.

[0050] After the end-capping reaction is completed, the reaction product is washed and dried.

[0051] Specifically, the reaction product was washed sequentially with toluene, methanol, and anhydrous ethanol, with each washing solvent being used three times. After washing, the product was vacuum dried overnight at 80°C to obtain the finished silica gel matrix C18 bonded adsorption packing material.

[0052] The silica matrix C18 bonded adsorption filler obtained in this embodiment has C18 alkyl groups bonded to its surface and is end-capped with trimethylchlorosilane.

[0053] Comparative Example 1: (1) Material preparation.

[0054] Take 100g of high-purity spherical porous silica gel, 500mL of toluene, 20g of octadecyltrichlorosilane and 10g of trimethylchlorosilane.

[0055] The high-purity spherical porous silica gel has a particle size of 5 μm and a specific surface area of ​​300 m² / g; toluene is used as an organic solvent; octadecyltrichlorosilane is used as a C18 alkylsilanizing agent; and trimethylchlorosilane is used as a chlorosilane end-capping agent.

[0056] (2) Step 1: C18 bonding reaction.

[0057] Add 100g of high-purity spherical porous silica gel to a three-necked reactor, add 500mL of toluene, and stir magnetically to evenly disperse the high-purity spherical porous silica gel in the toluene.

[0058] Subsequently, 20g of octadecyltrichlorosilane was added, and a small amount of nitrogen gas was introduced for reaction protection. The reaction temperature was controlled at 105℃, and the reaction was stirred for 24h to allow octadecyltrichlorosilane to undergo a C18 bonding reaction with the silanol groups on the surface of high-purity spherical porous silica gel.

[0059] After the C18 bonding reaction was completed, the reaction product was washed with toluene, methanol and anhydrous ethanol in sequence, three times with each washing solvent. After washing, the product was vacuum dried overnight at 80°C to obtain the C18 bonded silica intermediate.

[0060] (3) Second step: End capping reaction.

[0061] The C18 bonded silica intermediate obtained after washing and drying was added back into the three-necked reactor, and then 500 mL of toluene was added. The mixture was stirred to redisperse the silica gel.

[0062] Subsequently, 10g of trimethylchlorosilane was added to the three-necked reactor, the reaction temperature was controlled at 105℃, and the reaction was stirred for 6 hours to allow the trimethylchlorosilane to undergo a capping reaction with the residual silanol groups on the surface of the C18 bonded silica intermediate.

[0063] (4) Finished product processing.

[0064] After the end-capping reaction was completed, the product was washed with toluene, methanol and anhydrous ethanol in sequence, with each washing solvent being used three times. After washing, the product was vacuum dried overnight at 80°C to obtain the finished silica matrix C18 bonded adsorption packing material.

[0065] The main difference between Comparative Example 1 and Example 1 is that Comparative Example 1 performed intermediate washing, intermediate drying, and intermediate refeeding between the C18 bonding reaction and the end-capping reaction; while in Example 1, no intermediate washing and intermediate drying were performed after the C18 bonding reaction was completed. Instead, the acidic HCl byproduct was removed from the reaction vessel by nitrogen purging, and the end-capping reaction was carried out directly in the same reaction vessel.

[0066] Performance testing The performance of the silica matrix C18 bonded adsorption packing materials prepared in Example 1 and Comparative Example 1 were tested. The test items included specific surface area, C18 bond amount, end-capping rate, and adsorption capacity.

[0067] The detection method can be performed according to the national standard GB / T 32268-2015 "Determination of Performance of Octadecyl Bonded Phase (C18) High Performance Liquid Chromatography Column". The detection results are shown in the table below.

[0068] Specific surface area (m² / g) 138.4 139.6 ±1% C18 bond content (mmol / g) 1.25 1.24 ±0.02 End capping rate (%) 92.3 92.1 ±0.3% Adsorption capacity (mg / g) 85.6 85.3 ±0.5% As can be seen from the above test results, the silica matrix C18 bonded adsorption packing material prepared by the one-step method in Example 1 has little difference in specific surface area, C18 bond amount, end-capping rate and adsorption capacity compared with the silica matrix C18 bonded adsorption packing material prepared by the traditional two-step method in Comparative Example 1. The test results are within the allowable deviation range.

[0069] The above results show that after the C18 bonding reaction is completed, the acidic HCl byproducts are removed from the reaction vessel by nitrogen purging, and then trimethylchlorosilane is directly added for end-capping reaction. This method can obtain silica matrix C18 bonded adsorption packing material with performance close to that of the traditional two-step method without omitting intermediate washing and drying steps.

[0070] Comparative Example 2: This embodiment provides a one-step preparation process for C18 bonded adsorption filler in a silica matrix. After the silanization reaction, the system is not purged. This is compared with Example 1. (1) Material preparation.

[0071] Take 100g of high-purity spherical porous silica gel, 500mL of toluene, 20g of octadecyltrichlorosilane, 10g of trimethylchlorosilane, and nitrogen.

[0072] The high-purity spherical porous silica gel has a particle size of 5 μm and a specific surface area of ​​300 m² / g; toluene is used as an organic solvent; octadecyltrichlorosilane is used as a C18 alkylsilanizing agent; trimethylchlorosilane is used as a chlorosilane end-capping agent; and nitrogen is used as an inert gas.

[0073] (2) Silica matrix dispersion.

[0074] 100g of high-purity spherical porous silica gel was added to a three-necked reactor, and then 500mL of toluene was added to the reactor. The mixture was then magnetically stirred to ensure that the high-purity spherical porous silica gel was uniformly dispersed in the toluene.

[0075] In this step, toluene is used to form an organic reaction system, allowing the silica matrix to come into full contact with the subsequently added octadecyltrichlorosilane.

[0076] (3) C18 bonding reaction.

[0077] 20g of octadecyltrichlorosilane was added to a three-necked reactor, and a small amount of nitrogen gas was introduced into the reactor for reaction protection. Subsequently, the reaction temperature was controlled at 105℃, and the reaction was carried out for 24h under stirring to allow the octadecyltrichlorosilane to bond with the silanol groups on the surface of high-purity spherical porous silica gel.

[0078] In this reaction, octadecyltrichlorosilane reacts with the silanol groups on the surface of the silica matrix to form a C18 alkyl bonded layer on the surface of the silica matrix, and generates a reaction mixture containing HCl acidic byproducts.

[0079] (4) End-capping reaction.

[0080] After removing the acidic byproducts, 10g of trimethylchlorosilane was added directly to the same three-necked reactor. The reaction temperature was maintained at 105℃, and the mixture was stirred for 6 hours to allow the trimethylchlorosilane to undergo a capping reaction with the silanol groups remaining on the surface of the silica matrix.

[0081] In this step, since the acidic HCl byproducts have been removed from the reaction vessel by nitrogen purging in the previous step, trimethylchlorosilane can directly undergo the end-capping reaction in the same reaction system without having to wash, dry, and reintroduce the C18 bonded silica intermediate into the reaction system.

[0082] (5) Finished product processing.

[0083] After the end-capping reaction is completed, the reaction product is washed and dried.

[0084] Specifically, the reaction product was washed sequentially with toluene, methanol, and anhydrous ethanol, with each washing solvent being used three times. After washing, the product was vacuum dried overnight at 80°C to obtain the finished silica gel matrix C18 bonded adsorption packing material.

[0085] The silica matrix C18 bonded adsorption filler obtained in this embodiment has C18 alkyl groups bonded to its surface and is end-capped with trimethylchlorosilane.

[0086] The main difference between Example 2 and Example 1 is that in Example 1, nitrogen purging was used to remove the byproduct HCl between the silanization and end-capping steps. In Example 2, however, after the silanization reaction was completed, the byproduct HCl was not purged, and the second end-capping reaction was carried out in the same system.

[0087] Performance testing The performance of the silica matrix C18 bonded adsorption packings prepared in Examples 1 and 2 were tested. The test items included specific surface area and C18 bond amount.

[0088] The detection method can be performed according to the national standard GB / T 32268-2015 "Determination of Performance of Octadecyl Bonded Phase (C18) High Performance Liquid Chromatography Column". The detection results are shown in the table below.

[0089] Specific surface area (m² / g) 138.4 127.4 Over 1% C18 bond content (mmol / g) 1.25 0.884 Exceeding 0.02 The test results above show that the silica matrix C18 bonded adsorption packing material obtained by purging HCl byproducts with nitrogen in Example 1 has a large difference in specific surface area and C18 bond amount compared with the silica matrix packing material obtained without purging HCl byproducts in Example 2. The test results are not within the allowable deviation range.

[0090] The above results indicate that after the C18 bonding reaction is completed, the acidic HCl byproducts can be removed from the reaction vessel by purging with nitrogen, and then trimethylchlorosilane can be directly added for end-capping reaction, which can yield silica matrix C18 bonded adsorption packing with performance close to that of the traditional two-step method.

[0091] Comparative Example 3: This embodiment provides a one-step preparation process for C18 bonded adsorption filler in a silica matrix. After the silanization reaction, different purging conditions are implemented when purging the byproduct HCl: (1) Material preparation.

[0092] Take 100g of high-purity spherical porous silica gel, 500mL of toluene, 20g of octadecyltrichlorosilane, 10g of trimethylchlorosilane, and nitrogen.

[0093] The high-purity spherical porous silica gel has a particle size of 5 μm and a specific surface area of ​​300 m² / g; toluene is used as an organic solvent; octadecyltrichlorosilane is used as a C18 alkylsilanizing agent; trimethylchlorosilane is used as a chlorosilane end-capping agent; and nitrogen is used as an inert gas.

[0094] (2) Silica matrix dispersion.

[0095] 100g of high-purity spherical porous silica gel was added to a three-necked reactor, and then 500mL of toluene was added to the reactor. The mixture was then magnetically stirred to ensure that the high-purity spherical porous silica gel was uniformly dispersed in the toluene.

[0096] In this step, toluene is used to form an organic reaction system, allowing the silica matrix to come into full contact with the subsequently added octadecyltrichlorosilane.

[0097] (3) C18 bonding reaction.

[0098] 20g of octadecyltrichlorosilane was added to a three-necked reactor, and a small amount of nitrogen gas was introduced into the reactor for reaction protection. Subsequently, the reaction temperature was controlled at 105℃, and the reaction was carried out for 24h under stirring to allow the octadecyltrichlorosilane to bond with the silanol groups on the surface of high-purity spherical porous silica gel.

[0099] In this reaction, octadecyltrichlorosilane reacts with the silanol groups on the surface of the silica matrix to form a C18 alkyl bonded layer on the surface of the silica matrix, and generates a reaction mixture containing HCl acidic byproducts.

[0100] (4) Removal of acidic byproducts.

[0101] After the C18 bonding reaction is completed, the products in the reaction system are not subjected to intermediate washing and drying, nor are the reaction products removed from the three-necked reactor.

[0102] Maintain the temperature inside the three-necked reactor at 105℃, and continuously purge the reactor with nitrogen gas at a rate of 0.5 L / min for 3 hours. The continuous purging action of nitrogen gas will remove the residual acidic HCl byproducts from the reaction vessel.

[0103] In this step, nitrogen purging replaces the intermediate washing and drying processes following the C18 bonding reaction in traditional processes. By directly purging acidic byproducts within the same reaction vessel, the processes of removing, washing, drying, refeeding, and redispersing reaction products can be reduced.

[0104] (5) End-capping reaction.

[0105] After removing the acidic byproducts, 10g of trimethylchlorosilane was added directly to the same three-necked reactor. The reaction temperature was maintained at 105℃, and the mixture was stirred for 6 hours to allow the trimethylchlorosilane to undergo a capping reaction with the silanol groups remaining on the surface of the silica matrix.

[0106] In this step, since the acidic HCl byproducts have been removed from the reaction vessel by nitrogen purging in the previous step, trimethylchlorosilane can directly undergo the end-capping reaction in the same reaction system without having to wash, dry, and reintroduce the C18 bonded silica intermediate into the reaction system.

[0107] (6) Finished product processing.

[0108] After the end-capping reaction is completed, the reaction product is washed and dried.

[0109] Specifically, the reaction product was washed sequentially with toluene, methanol, and anhydrous ethanol, with each washing solvent being used three times. After washing, the product was vacuum dried overnight at 80°C to obtain the finished silica gel matrix C18 bonded adsorption packing material.

[0110] The silica matrix C18 bonded adsorption filler obtained in this embodiment has C18 alkyl groups bonded to its surface and is end-capped with trimethylchlorosilane.

[0111] Comparative Example 4: This embodiment provides a one-step preparation process for C18 bonded adsorption filler in a silica matrix. After the silanization reaction, different purging conditions are implemented when purging the byproduct HCl: (1) Material preparation.

[0112] Take 100g of high-purity spherical porous silica gel, 500mL of toluene, 20g of octadecyltrichlorosilane, 10g of trimethylchlorosilane, and nitrogen.

[0113] The high-purity spherical porous silica gel has a particle size of 5 μm and a specific surface area of ​​300 m² / g; toluene is used as an organic solvent; octadecyltrichlorosilane is used as a C18 alkylsilanizing agent; trimethylchlorosilane is used as a chlorosilane end-capping agent; and nitrogen is used as an inert gas.

[0114] (2) Silica matrix dispersion.

[0115] 100g of high-purity spherical porous silica gel was added to a three-necked reactor, and then 500mL of toluene was added to the reactor. The mixture was then magnetically stirred to ensure that the high-purity spherical porous silica gel was uniformly dispersed in the toluene.

[0116] In this step, toluene is used to form an organic reaction system, allowing the silica matrix to come into full contact with the subsequently added octadecyltrichlorosilane.

[0117] (3) C18 bonding reaction.

[0118] 20g of octadecyltrichlorosilane was added to a three-necked reactor, and a small amount of nitrogen gas was introduced into the reactor for reaction protection. Subsequently, the reaction temperature was controlled at 105℃, and the reaction was carried out for 24h under stirring to allow the octadecyltrichlorosilane to bond with the silanol groups on the surface of high-purity spherical porous silica gel.

[0119] In this reaction, octadecyltrichlorosilane reacts with the silanol groups on the surface of the silica matrix to form a C18 alkyl bonded layer on the surface of the silica matrix, and generates a reaction mixture containing HCl acidic byproducts.

[0120] (4) Removal of acidic byproducts.

[0121] After the C18 bonding reaction is completed, the products in the reaction system are not subjected to intermediate washing and drying, nor are the reaction products removed from the three-necked reactor.

[0122] Maintain the temperature inside the three-necked reactor at 105℃, and continuously purge the reactor with nitrogen gas at a rate of 2L / min for 1 hour. The continuous purging action of nitrogen gas will remove the residual acidic HCl byproducts from the reaction vessel.

[0123] In this step, nitrogen purging replaces the intermediate washing and drying processes following the C18 bonding reaction in traditional processes. By directly purging acidic byproducts within the same reaction vessel, the processes of removing, washing, drying, refeeding, and redispersing reaction products can be reduced.

[0124] (5) End-capping reaction.

[0125] After removing the acidic byproducts, 10g of trimethylchlorosilane was added directly to the same three-necked reactor. The reaction temperature was maintained at 105℃, and the mixture was stirred for 6 hours to allow the trimethylchlorosilane to undergo a capping reaction with the silanol groups remaining on the surface of the silica matrix.

[0126] In this step, since the acidic HCl byproducts have been removed from the reaction vessel by nitrogen purging in the previous step, trimethylchlorosilane can directly undergo the end-capping reaction in the same reaction system without having to wash, dry, and reintroduce the C18 bonded silica intermediate into the reaction system.

[0127] (6) Finished product processing.

[0128] After the end-capping reaction is completed, the reaction product is washed and dried.

[0129] Specifically, the reaction product was washed sequentially with toluene, methanol, and anhydrous ethanol, with each washing solvent being used three times. After washing, the product was vacuum dried overnight at 80°C to obtain the finished silica gel matrix C18 bonded adsorption packing material.

[0130] The silica matrix C18 bonded adsorption filler obtained in this embodiment has C18 alkyl groups bonded to its surface and is end-capped with trimethylchlorosilane.

[0131] The main difference between Example 3 and Example 4 is that the flow rate of nitrogen gas used to purge the acidic byproducts of HCl was tested under different conditions between the silanization reaction and the end-capping reaction steps.

[0132] Performance testing The performance of the silica matrix C18 bonded adsorption packing materials prepared in Examples 3 and 4 were tested. The test items included specific surface area, C18 bond amount, end-capping rate, and adsorption capacity.

[0133] The detection method can be performed according to the national standard GB / T 32268-2015 "Determination of Performance of Octadecyl Bonded Phase (C18) High Performance Liquid Chromatography Column". The detection results are shown in the table below.

[0134] Specific surface area (m² / g) 138.4 138.6 139.2 ±1% C18 bond content (mmol / g) 1.25 1.23 1.25 ±0.02 End capping rate (%) 92.3 92.2 92.1 ±0.3% Adsorption capacity (mg / g) 85.6 85.5 85.4 ±0.5% As can be seen from the above test results, the silica matrix C18 bonded adsorption packing prepared by the one-step method in Examples 3 and 4 after adjusting the nitrogen flow rate has little difference in specific surface area, C18 bond amount, end-capping rate and adsorption capacity compared with the silica matrix C18 bonded adsorption packing prepared by the traditional two-step method in Comparative Example 1. The test results are within the allowable deviation range.

[0135] The above results show that after the C18 bonding reaction is completed, adjusting the flow rate and time of nitrogen gas used to purge the byproduct HCl into the reactor does not change the product performance, and silica matrix C18 bonded adsorption packing with performance close to that of the traditional two-step method can be obtained.

[0136] Furthermore, compared to Comparative Example 1, Example 1 reduces the intermediate washing, drying, intermediate refeeding, and redispersing processes between the C18 bonding reaction and the end-capping reaction. Therefore, the process described in Example 1 can shorten the preparation process, reduce washing solvent consumption and drying energy consumption, and reduce the risk of introducing impurities or causing batch fluctuations during intermediate product transfer.

[0137] In other embodiments, the silica matrix can be high-purity spherical porous silica suitable for C18 bonding reactions. The particle size, pore size, and specific surface area of ​​the high-purity spherical porous silica can be conventionally selected according to the actual separation application requirements. As long as the silica matrix surface has silanol groups capable of reacting with C18 alkylsilanizing agents, it can be used in the preparation process of this invention.

[0138] In other embodiments, the organic solvent is preferably toluene. Toluene enables the octadecylchlorosilane reagent to be well dispersed in the reaction system and facilitates sufficient contact between the silica matrix and the C18 alkylsilanizing reagent. Depending on the actual process conditions, other organic solvents that are compatible with the C18 alkylsilanization reaction and do not significantly interfere with the bonding and end-capping reactions can also be selected.

[0139] In other embodiments, the preset temperature range can be 80-110°C. When the reaction temperature is below this range, the bonding reaction rate between the C18 alkylsilanizing agent and the silanol groups on the silica matrix surface may decrease; when the reaction temperature is too high, it may increase the risk of organic solvent evaporation, reaction system fluctuations, or side reactions. Therefore, controlling the preset temperature range at 80-110°C is beneficial for balancing bonding reaction efficiency and reaction process stability.

[0140] In other embodiments, the bonding reaction can take 12-24 hours. This reaction time setting allows the C18 alkyl silanizing agent to fully contact and bond with the silanol groups on the silica matrix surface, thereby forming a C18 alkyl bonded layer.

[0141] In other embodiments, the temperature inside the reaction vessel can be maintained within the preset temperature range during steps (c) and (d). This setting allows the acidic byproduct removal process and the end-capping reaction process to continue from the reaction state after the bonding reaction, avoiding additional process fluctuations in the reaction system due to cooling, discharging, drying, refeeding, and reheating.

[0142] In other embodiments, the inert gas can be introduced for 1-3 hours at a rate of 0.5-2 L / min. If the inert gas introduction time is too short or the introduction rate is too low, acidic byproducts may not be sufficiently removed, thus affecting subsequent end-capping reactions. If the inert gas introduction rate is too high, it may cause excessive disturbance in the reaction system, which is detrimental to maintaining the stability of the C18 bonded layer and the silica gel dispersion. Therefore, controlling the inert gas introduction time and rate within the above-mentioned range is beneficial for achieving a balance between the removal of acidic byproducts and the stability of the reaction system.

[0143] In other embodiments, the inert gas may be one or a mixture of nitrogen and argon. Nitrogen and argon are not readily reactive with C18 alkylsilanizing agents, chlorosilane end-capping agents, and silica matrix, and can be used as purge and protective gases.

[0144] In other embodiments, during the bonding reaction and the end-capping reaction, an inert gas can be introduced into the reaction vessel for reaction protection. This reaction protection differs from the purging removal of acidic byproducts in step (c). Reaction protection primarily reduces interference from external factors such as air, moisture, or oxygen on the reaction process; purging removal of acidic byproducts primarily removes the acidic byproducts generated in the bonding reaction from the reaction vessel, providing a suitable reaction environment for the subsequent end-capping reaction.

[0145] In other embodiments, the capping reaction can take 4-8 hours. This reaction time setting allows the chlorosilane capping reagent to fully react with the residual silanol groups on the silica matrix surface, thereby reducing the impact of the residual silanol groups on the adsorption performance and separation stability of the C18 bonded adsorption filler in the silica matrix.

[0146] In other embodiments, the C18 alkylsilanizing agent can be an octadecylchlorosilane, preferably octadecyltrichlorosilane. Octadecylchlorosilanes can undergo silanization bonding with the silanol groups on the surface of the silica matrix, generating acidic byproducts. These acidic byproducts can be removed from the reaction vessel by purging with an inert gas.

[0147] In other embodiments, the chlorosilane end-capping agent may be selected from at least one of trimethylchlorosilane, dimethyldichlorosilane, or diphenylmethylchlorosilane. All of the above chlorosilane end-capping agents can react with residual silanol groups on the surface of the silica matrix to achieve end-capping treatment.

[0148] In summary, this invention transforms the preparation process of silica-based C18 bonded adsorbents from a traditional stepwise process into a continuous one-step process by sequentially performing the C18 bonding reaction, inert gas purging to remove acidic byproducts, and chlorosilane end-capping reaction in the same reaction vessel. This process reduces intermediate washing, drying, and intermediate transfer steps while achieving silica-based C18 bonded adsorbents with performance close to that of the traditional two-step method.

[0149] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. A one-step preparation process for C18 bonded adsorption fillers in a silica matrix, characterized in that, Includes the following steps: (a) Add silica gel matrix and organic solvent to the reaction vessel respectively, so that the silica gel matrix is ​​dispersed in the organic solvent; (b) A C18 alkylsilanizing agent is added to the reaction vessel to carry out a bonding reaction; (c) After the bonding reaction is completed, without intermediate washing and drying, an inert gas is directly introduced into the reaction vessel to purge the acidic byproducts generated by the bonding reaction. (d) After purging, add a chlorosilane end-capping agent to the reaction vessel to carry out the end-capping reaction; (e) After the end-capping reaction is completed, the silica matrix C18 bonded adsorption packing is obtained by washing and drying.

2. The one-step preparation process of the silica matrix C18 bonded adsorption filler according to claim 1, characterized in that, In step (a), the silicone matrix is ​​spherical porous silicone.

3. The one-step preparation process of the silica matrix C18 bonded adsorption filler according to claim 1, characterized in that, In step (a), the organic solvent is toluene.

4. The one-step preparation process of the silica matrix C18 bonded adsorption filler according to claim 1, characterized in that, In step (b), the bonding reaction is carried out at a preset temperature range of 80-110°C for a reaction time of 12-24 h; the C18 alkylsilanizing agent is octadecyltrichlorosilane.

5. The one-step preparation process of the silica matrix C18 bonded adsorption filler according to claim 4, characterized in that, In steps (c) and (d), the temperature inside the reaction vessel is maintained within the preset temperature range.

6. The one-step preparation process of the silica matrix C18 bonded adsorption filler according to claim 1, characterized in that, In step (c), the inert gas is introduced for 1-3 hours at a rate of 0.5-2 L / min.

7. The one-step preparation process of the silica matrix C18 bonded adsorption filler according to claim 1, characterized in that, In step (c), the inert gas is introduced by continuous purging.

8. The one-step preparation process of the silica matrix C18 bonded adsorption filler according to claim 1, characterized in that, In both steps (b) and (d), an inert gas is introduced into the reaction vessel to protect the reaction.

9. The one-step preparation process of the silica matrix C18 bonded adsorption filler according to claim 1, characterized in that, In step (d), the reaction time for the end-capping reaction is 4-8 hours; the chlorosilane end-capping reagent is selected from at least one of trimethylchlorosilane, dimethyldichlorosilane, or diphenylmethylchlorosilane.

10. A silica-based C18 bonded adsorption filler, characterized in that, It is prepared by any one of the preparation processes according to claims 1 to 9.

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