Modified activated carbon material for catalyst carrier and method for preparing the same
By introducing functionalized onion carbon and N-hydroxyethylimine diacetic acid onto the surface of activated carbon, the problem of uniform distribution of active components within the activated carbon was solved, achieving stable fixation of the catalyst and high-efficiency catalytic performance, thereby improving the catalyst's lifespan and conversion rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-09
- Publication Date
- 2026-07-10
AI Technical Summary
Existing catalyst support materials suffer from the problem that the active components are difficult to distribute evenly within the activated carbon, resulting in insufficient bonding strength, easy wear and detachment, decreased catalytic efficiency, and poor cycle performance.
By introducing functionalized onion carbon and N-hydroxyethylimine diacetic acid onto the surface of activated carbon, and treating it with mercaptosilane coupling agent and acid catalyst, dithioacetal and esterification reactions are generated, achieving deep and uniform distribution and stable fixation of active components.
It improves the catalyst's resistance to wear, enhances its catalytic performance and stability, extends its service life, and increases the catalytic conversion rate.
Smart Images
Figure CN122355290A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to a modified activated carbon material for catalyst support and its preparation method. Background Technology
[0002] With the rapid development of modern chemical industry and environmental protection, high-performance catalysts are playing an increasingly prominent role in processes such as organic synthesis, pollutant degradation, and energy conversion. As the dispersion substrate for active components, the structure and surface properties of the catalyst support directly determine the overall efficiency of the catalytic system. Among numerous support materials, activated carbon is considered a highly promising new environmentally friendly support material due to its unique pore size distribution, highly developed specific surface area, and excellent chemical stability. It not only provides ample reaction interfaces for catalytic reactions but also possesses good adsorption capacity and promising prospects for resource utilization, thus demonstrating broad application potential in the construction of high-value-added catalytic materials.
[0003] In the selection of active components for catalysts, platinum group metals such as platinum (Pt) and palladium (Pd) are widely used in various hydrogenation, oxidation, and electrocatalytic reactions due to their excellent catalytic activity, selectivity, and stability. Loading these precious metals onto activated carbon supports can fully utilize the structural advantages of activated carbon, achieving high dispersion and effective fixation of the active components. However, existing conventional loading processes still have significant technical drawbacks: most active components can only be deposited in the microporous regions near the outer surface of the activated carbon, making it difficult to achieve uniform distribution into the internal pores of the particles. This surface enrichment phenomenon leads to insufficient bonding strength between the active components and the support, making the catalyst prone to wear and detachment during use (especially under conditions of mechanical friction or fluid scouring, such as fluidized beds and stirred reactors). This results in the loss of catalytic material, leading to a significant decrease in activity during recycling, poor overall cycle performance, and difficulty in maintaining long-term stable catalytic efficiency.
[0004] Therefore, current catalytic applications place more stringent demands on high-performance support materials: catalyst supports not only need to have a high specific surface area and a suitable pore structure to achieve efficient loading of active components, but also need to ensure that the active components are deeply and uniformly distributed inside the support, thereby enhancing their wear resistance and reducing loss, and maintaining longer-lasting catalytic efficiency. Summary of the Invention
[0005] The purpose of this invention is to provide a modified activated carbon material for catalyst support and its preparation method. When used as a catalyst support, the modified activated carbon material has excellent active material immobilization effect and long-term stability, which is beneficial to improving catalytic conversion rate.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a method for preparing a modified activated carbon material for a catalyst support, comprising the following steps: (1) Add pretreated activated carbon and mercapto-containing silane coupling agent to an ethanol aqueous solution, stir to react, then add functionalized onion carbon and catalyst to continue the reaction, filter, wash and dry to obtain activated carbon loaded with onion carbon. (2) Under the action of an acidic catalyst, activated carbon loaded with onion carbon and N-hydroxyethylimine diacetic acid are reacted in N,N-dimethylformamide to obtain modified activated carbon material.
[0007] In the above steps, the present invention first uses acid to treat the surface of activated carbon, exposing more active sites, introducing oxygen-containing functional groups, improving surface activity, and providing reaction sites for subsequent reactions; then, it uses a mercaptosilane coupling agent to react with the acid-treated activated carbon, so that the activated carbon carries mercapto groups. The mercapto groups react with the aldehyde groups on the surface of the functionalized onion carbon under acidic conditions to generate dithioacetal, thus grafting the onion carbon onto the activated carbon; finally, the hydroxyl groups on the surface of the onion carbon undergo an esterification reaction with the carboxyl groups in N-hydroxyethylimine diacetic acid under the catalysis of concentrated sulfuric acid, so that N-hydroxyethylimine diacetic acid is grafted onto the onion carbon, thereby obtaining the modified activated carbon material.
[0008] Furthermore, the functionalized onion carbon described in step (1) is prepared by the following process: (a) Add onion carbon to a mixed acid, disperse by ultrasonication, heat and stir, and then centrifuge and wash to obtain pretreated onion carbon; (b) Under an ammonia atmosphere, the pretreated onion carbon was subjected to plasma treatment to obtain aminated onion carbon; (c) Aminated onion carbon, hydroxymalondialdehyde and sodium cyanoborohydride were added sequentially to dimethyl sulfoxide, stirred and reacted, and then separated, washed and dried to obtain functionalized onion carbon.
[0009] In the above steps, the present invention first treats the onion carbon with acid to expose more active sites on the surface of the onion carbon, introduces oxygen-containing functional groups such as carboxyl and hydroxyl groups, improves surface activity, and provides reaction sites for subsequent reactions. Then, ammonia is decomposed into amino and hydrogen by plasma. The amino groups, as free radicals, react with the oxygen-containing groups on the surface of the onion carbon to graft amino groups onto the surface of the onion carbon. Finally, the grafted amino groups and the aldehyde groups in excess hydroxymalondialdehyde undergo a Schiff base reaction to generate C=N bonds. Sodium cyanoborohydride is used as a reducing agent to reduce the C=N bonds to CH-NH bonds, thereby obtaining functionalized onion carbon.
[0010] Further, the mixed acid in step (a) is composed of a 65% mass fraction concentrated nitric acid solution and a 98% mass fraction concentrated sulfuric acid solution in a volume ratio of 1:(2.8-3.2); the ratio of the amount of onion carbon to the mixed acid is 1g:(320-360)mL; the heating and stirring temperature is 70-80 ℃ and the time is 20-30 h.
[0011] Further, in step (b), the plasma treatment power is 150-200 W, the ammonia flow rate is 20-30 mL / min, the pressure is 2-5 kPa, and the time is 0.5-1 h.
[0012] Further, in step (c), the ratio of hydroxymalondialdehyde, aminated onion carbon, sodium cyanoborohydride and dimethyl sulfoxide is 5 g: (0.5-0.6) g: (0.05-0.1) g: (95-100) mL; and the stirring reaction time is 3-8 h.
[0013] Further, the pretreated activated carbon in step (1) is obtained by soaking activated carbon in a nitric acid solution; the mass fraction of the nitric acid solution is 1-5 wt%; the ratio of activated carbon to nitric acid solution is 1 g: (10-15) mL; the soaking temperature is 50-70 ℃ and the soaking time is 1-2 h.
[0014] Further, the mercapto-containing silane coupling agent in step (1) is KH590; the catalyst is p-toluenesulfonic acid; and the volume fraction of ethanol in the aqueous ethanol solution is 25-30%.
[0015] Furthermore, the catalyst mentioned in step (1) refers to a catalyst used to promote the reaction between thiol and aldehyde groups.
[0016] Further, in step (1), the ratio of the amount of pretreated activated carbon, mercapto-containing silane coupling agent, functionalized onion carbon, catalyst and ethanol aqueous solution is 10 g: (1-2) g: (0.25-0.5) g: (0.1-0.15) g: (80-160) mL; the temperature of the stirring reaction is 40-60 ℃, the time is 0.5-1.5 h; and the reaction continues for 1-2 h.
[0017] Further, the acidic catalyst in step (2) is a concentrated sulfuric acid solution with a mass fraction of 98%; the ratio of the activated carbon supported onion carbon, N-hydroxyethylimine diacetic acid, acidic catalyst and N,N-dimethylformamide is 10 g: (0.6-1.2) g: (0.5-1) mL: (50-80) mL; the reaction temperature is 80-100 ℃ and the time is 3-5 h.
[0018] A second aspect of the present invention provides a modified activated carbon material for catalyst support prepared by the preparation method described in the first aspect above.
[0019] The beneficial technical effects of this invention are as follows: 1. This invention introduces functionalized onion carbon with a concentric graphite shell structure into activated carbon. The excellent electrical conductivity and high curvature surface of onion carbon, when combined with activated carbon, can improve the conductivity and pore volume of the support, which is beneficial to improving catalytic performance. Simultaneously, the good structural stability and corrosion resistance of onion carbon can inhibit the oxidative corrosion and structural collapse of activated carbon, thereby extending the catalyst's lifespan and cycle stability. After functionalization modification of onion carbon (introducing active groups such as aldehydes), its surface active sites increase, enabling it to form a stable chemical bond with the activated carbon matrix. It also provides more anchoring sites to strongly fix the active components of the catalyst, effectively inhibiting catalyst migration and aggregation on the support surface, and synergistically improving the catalyst's catalytic performance.
[0020] 2. This invention utilizes N-hydroxyethyliminodiacetic acid to graft-modify activated carbon supported onion carbon. N-hydroxyethyliminodiacetic acid has multiple active sites such as carboxyl and hydroxyl groups, which can form stable chelates with various metal ions, significantly increasing the support's ability to capture and immobilize the catalyst. In addition, the abundant polar groups can enhance the hydrophilicity of activated carbon, improve the dispersion stability of the support in aqueous phase or organic solvents, and facilitate the improvement of the contact between the catalyst and reactants, further enhancing the catalytic performance. Attached Figure Description
[0021] Figure 1 The image shown is a scanning electron microscope image of the functionalized onion carbon prepared in Example 1 of this invention. Figure 2 This is a scanning electron microscope (SEM) image of the modified activated carbon material for catalyst support prepared in Example 1 of this invention. Figure 3 The image shows the plasma atomic emission spectrum of the catalyst prepared in Example 1 of this invention before catalytic testing. Figure 4 The image shows the plasma atomic emission spectrum of the catalyst prepared in Example 1 of this invention after catalytic testing. Figure 5 The image shows the plasma atomic emission spectrum of the catalyst prepared in Example 2 of this invention after catalytic testing. Figure 6 The plasma atomic emission spectrum of the catalyst prepared in Example 3 of this invention after catalytic testing is shown. Figure 7 The plasma atomic emission spectrum of the catalyst prepared in Comparative Example 1 of this invention after catalytic testing is shown. Figure 8The plasma atomic emission spectrum of the catalyst prepared in Comparative Example 2 of this invention after catalytic testing is shown. Figure 9 The plasma atomic emission spectrum of the catalyst prepared in Comparative Example 3 of this invention after catalytic testing is shown. Figure 10 This is a high-performance liquid chromatography (HPLC) of the reaction solution before catalytic testing in the test examples of this invention; Figure 11 The high-performance liquid chromatography of the reaction solution after catalytic testing of the catalyst prepared in Example 1 of this invention; Figure 12 The high-performance liquid chromatography of the reaction solution after catalytic testing of the catalyst prepared in Example 2 of this invention; Figure 13 The catalyst prepared in Example 3 of this invention is subjected to high performance liquid chromatography of the reaction solution after catalytic testing; Figure 14 High-performance liquid chromatography of the reaction solution after catalytic testing of the catalyst prepared in Comparative Example 1 of this invention; Figure 15 The high-performance liquid chromatography of the reaction solution after catalytic testing of the catalyst prepared in Comparative Example 2 of this invention; Figure 16 High-performance liquid chromatography of the reaction solution after catalytic testing of the catalyst prepared in Comparative Example 3 of this invention; Figure 17 This is a high-performance liquid chromatogram of the reaction solution obtained after the catalyst prepared in Example 1 of the present invention was reused 5 times; Figure 18 This is a high-performance liquid chromatogram of the reaction solution obtained after the catalyst prepared in Example 2 of the present invention was reused 5 times; Figure 19 This is a high-performance liquid chromatogram of the reaction solution obtained after the catalyst prepared in Example 3 of the present invention was reused 5 times; Figure 20 The high-performance liquid chromatogram of the reaction solution obtained after the catalyst prepared in Comparative Example 1 of the present invention was reused 5 times. Figure 21 The high-performance liquid chromatogram of the reaction solution obtained after the catalyst prepared in Comparative Example 2 of the present invention was reused 5 times. Figure 22 This is a high-performance liquid chromatogram of the reaction solution obtained after the catalyst prepared in Comparative Example 3 of this invention was reused 5 times. Detailed Implementation
[0022] The following is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.
[0023] (a) Preparation example Preparation Example 1 Preparation Example 1 provides a functionalized onion carbon, which is prepared by the following steps: (a) Mix 65% nitric acid solution and 98% sulfuric acid solution in a volume ratio of 1:3 to form a mixed acid; add onion carbon to the mixed acid in a ratio of 1 g:340 mL and ultrasonically disperse for 30 min, then stir at 70 °C for 24 h, centrifuge and wash to obtain pretreated onion carbon. (b) The pretreated onion carbon was placed in a plasma processor chamber with an ammonia atmosphere. The plasma treatment power was set to 180 W, the ammonia flow rate was 25 mL / min, and the pressure was 3 kPa. The pretreated onion carbon was subjected to plasma treatment for 0.8 h to obtain aminated onion carbon. (c) Following a ratio of 5 g: 0.6 g: 0.08 g: 98 mL for hydroxymalondialdehyde, amino-modified onion carbon, sodium cyanoborohydride, and dimethyl sulfoxide, amino-modified onion carbon, hydroxymalondialdehyde, and sodium cyanoborohydride were sequentially added to dimethyl sulfoxide. The mixture was stirred for 6 h, and after separation, washing, and drying, functionalized onion carbon was obtained. A scanning electron microscope image of this functionalized onion carbon is shown below. Figure 1 As shown.
[0024] Preparation Example 2 Preparation Example 2 provides a functionalized onion carbon, which is prepared by the following steps: (a) Mix 65% nitric acid solution and 98% sulfuric acid solution at a volume ratio of 1:2.8 to form a mixed acid; add onion carbon to the mixed acid at a ratio of 1 g:360 mL and ultrasonically disperse for 20 min, then stir at 70 °C for 30 h, centrifuge and wash to obtain pretreated onion carbon. (b) The pretreated onion carbon was placed in the plasma processor cavity under an ammonia atmosphere. The plasma treatment power was set to 150 W, the ammonia flow rate was 20 mL / min, and the pressure was 2 kPa. The pretreated onion carbon was subjected to plasma treatment for 1 h to obtain aminated onion carbon. (c) Following the ratio of hydroxymalondialdehyde, aminated onion carbon, sodium cyanoborohydride, and dimethyl sulfoxide of 5 g: 0.5 g: 0.05 g: 95 mL, aminated onion carbon, hydroxymalondialdehyde, and sodium cyanoborohydride were added sequentially to dimethyl sulfoxide and stirred for 3 h. After separation, washing, and drying, functionalized onion carbon was obtained.
[0025] Preparation Example 3 Preparation Example 3 provides a functionalized onion carbon, which is prepared by the following steps: (a) A 65% nitric acid solution and a 98% sulfuric acid solution were mixed evenly to form a mixed acid, with a volume ratio of 1:3.2 between concentrated nitric acid solution and concentrated sulfuric acid solution. Onion carbon was added to the mixed acid and ultrasonically dispersed for 40 min, then stirred at 80 °C for 20 h. After centrifugation and washing, pretreated onion carbon was obtained. (b) The pretreated onion carbon was placed in a plasma processor chamber with an ammonia atmosphere. The plasma treatment power was set to 200 W, the ammonia flow rate to 30 mL / min, and the pressure to 5 kPa. The pretreated onion carbon was subjected to plasma treatment for 0.5 h to obtain aminated onion carbon. (c) Following the ratio of hydroxymalondialdehyde, aminated onion carbon, sodium cyanoborohydride and dimethyl sulfoxide of 5 g: 0.6 g: 0.1 g: 100 mL, aminated onion carbon, hydroxymalondialdehyde and sodium cyanoborohydride were added to dimethyl sulfoxide in sequence, stirred for 8 h, and then separated, washed and dried to obtain functionalized onion carbon.
[0026] (II) Implementation Examples Example 1 Example 1 provides a method for preparing modified activated carbon material for catalyst support, comprising the following steps: (1) According to the ratio of activated carbon to nitric acid solution of 1 g: 12 mL, the activated carbon was added to a nitric acid solution with a mass fraction of 3 wt%, and then soaked at 60 °C for 1 h. After filtration, washing and drying, pretreated activated carbon was obtained. Then, according to the ratio of pretreated activated carbon, silane coupling agent KH590, functionalized onion carbon, p-toluenesulfonic acid and ethanol aqueous solution of 10 g: 1 g: 0.4 g: 0.12 g: 120 mL, the pretreated activated carbon and silane coupling agent KH590 were added to an ethanol aqueous solution with a volume fraction of 25%, and stirred at 50 °C for 1 h. Then, the functionalized onion carbon and p-toluenesulfonic acid of Preparation Example 1 were added and stirred for another 1 h. After filtration, washing and drying, activated carbon loaded with onion carbon was obtained. (2) According to the ratio of activated carbon loaded with onion carbon, N-hydroxyethylimine diacetic acid, concentrated sulfuric acid and N,N-dimethylformamide, 10 g: 1 g: 0.8 mL: 60 mL, the activated carbon loaded with onion carbon and N-hydroxyethylimine diacetic acid were added to N,N-dimethylformamide and mixed evenly. Then, 98% concentrated sulfuric acid solution was slowly added dropwise. The mixture was then reacted at 90 °C for 4 h. After filtration, washing and drying, the modified activated carbon material for catalyst support was obtained.
[0027] This embodiment also provides a modified activated carbon material for catalyst support prepared by the above method, and a scanning electron microscope image of the modified activated carbon material for catalyst support is shown below. Figure 2 As shown, combined with Figure 1 Morphology and properties of functionalized onion carbon raw materials Figure 2 The microstructure of the modified activated carbon clearly shows that the functionalized onion carbon particles are distributed on the surface of the activated carbon matrix, and that the onion carbon particles are embedded inside the activated carbon, indicating that the two achieve a strong grafted composite through chemical bonds.
[0028] Example 2 Example 2 provides a method for preparing modified activated carbon material for catalyst support, comprising the following steps: (1) According to the ratio of activated carbon to nitric acid solution of 1 g: 10 mL, the activated carbon was added to a nitric acid solution with a mass fraction of 5 wt%, and then soaked at 50 °C for 2 h. After filtration, washing and drying, pretreated activated carbon was obtained. Then, according to the ratio of pretreated activated carbon, silane coupling agent KH590, functionalized onion carbon, p-toluenesulfonic acid and ethanol aqueous solution of 10 g: 1 g: 0.25 g: 0.1 g: 80 mL, the pretreated activated carbon and silane coupling agent KH590 were added to an ethanol aqueous solution with a volume fraction of 30%, and stirred at 40 °C for 1.5 h. Then, the functionalized onion carbon and p-toluenesulfonic acid of Preparation Example 2 were added and stirred for another 2 h. After filtration, washing and drying, activated carbon loaded with onion carbon was obtained. (2) According to the ratio of activated carbon loaded with onion carbon, N-hydroxyethylimine diacetic acid, concentrated sulfuric acid and N,N-dimethylformamide, 10 g: 0.6 g: 0.5 mL: 50 mL, the activated carbon loaded with onion carbon and N-hydroxyethylimine diacetic acid were added to N,N-dimethylformamide and mixed evenly. Then, 98% concentrated sulfuric acid solution was slowly added dropwise. The mixture was then reacted at 80 °C for 5 h. After filtration, washing and drying, the modified activated carbon material for catalyst support was obtained.
[0029] This embodiment also provides a modified activated carbon material for catalyst support prepared by the above method.
[0030] Example 3 Example 3 provides a method for preparing modified activated carbon material for catalyst support, comprising the following steps: (1) According to the ratio of activated carbon to nitric acid solution of 1 g: 15 mL, the activated carbon was added to a nitric acid solution with a mass fraction of 1 wt%, and then soaked at 70 °C for 1 h. After filtration, washing and drying, pretreated activated carbon was obtained. Then, according to the ratio of pretreated activated carbon, silane coupling agent KH590, functionalized onion carbon, p-toluenesulfonic acid and ethanol aqueous solution of 10 g: 2 g: 0.5 g: 0.15 g: 160 mL, the pretreated activated carbon and silane coupling agent KH590 were added to an ethanol aqueous solution with a volume fraction of 30%, and stirred at 60 °C for 0.5 h. Then, the functionalized onion carbon and p-toluenesulfonic acid of Preparation Example 3 were added and stirred for another 1 h. After filtration, washing and drying, activated carbon loaded with onion carbon was obtained. (2) According to the ratio of activated carbon loaded with onion carbon, N-hydroxyethylimine diacetic acid, concentrated sulfuric acid and N,N-dimethylformamide, 10 g: 1.2 g: 1 mL: 80 mL, the activated carbon loaded with onion carbon and N-hydroxyethylimine diacetic acid were added to N,N-dimethylformamide and mixed evenly. Then, 98% concentrated sulfuric acid solution was slowly added dropwise. The mixture was then reacted at 100 °C for 3 h. After filtration, washing and drying, the modified activated carbon material for catalyst support was obtained.
[0031] This embodiment also provides a modified activated carbon material for catalyst support prepared by the above method.
[0032] (III) Comparative Example Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that the functionalized onion carbon in step (1) is omitted and the silane coupling agent KH590 is replaced with the silane coupling agent KH550.
[0033] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that the functionalized onion carbon in step (1) is replaced with onion carbon, and the silane coupling agent KH590 is replaced with silane coupling agent KH550.
[0034] Comparative Example 3 Comparative Example 3 is basically the same as Example 1, except that step (2) is omitted, i.e., activated carbon loaded with onion carbon is used as the catalyst carrier.
[0035] (iv) Test Examples The catalyst supports prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests.
[0036] Take 80 g of the catalyst supports prepared in Examples 1-3 and Comparative Examples 1-3 respectively, add them to 50 mL of chloropalladium acid solution with a palladium content (mass fraction) of 15%, mix them evenly, adjust the pH to 5.8 under stirring, filter out the solid material, age for 24 h, then reduce with hydrogen at 200 °C for 5 h, cool to room temperature, wash and obtain the catalyst.
[0037] Catalytic testing procedure: 1 g of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 were weighed and added to the reaction vessels. 0.8 g of p-carboxybenzaldehyde and 500 mL of water were added to each reaction vessel. The reaction was carried out at a temperature of 260 °C, an H₂ partial pressure of 0.6 MPa, and a reaction time of 1 h. After the reaction, the palladium loss rate, the initial conversion rate of p-carboxybenzaldehyde, and the conversion rate after multiple catalyst reuses were measured.
[0038] Palladium loss rate: The palladium content in the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 before and after the catalytic test was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES), and the palladium loss rate was calculated; Figure 3-9 The figures shown are plasma atomic emission spectra of the catalyst prepared in Example 1 before testing, and plasma atomic emission spectra of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 after testing.
[0039] Conversion rate test: High performance liquid chromatography (HPLC) was used to quantitatively analyze the content of p-carboxybenzaldehyde in the reaction solution before and after the reaction. The conversion rate was calculated based on the reduction of p-carboxybenzaldehyde before and after the reaction. The conversion rates of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 were statistically analyzed during the first catalysis, and the conversion rates were also statistically analyzed after the catalysts were separated, washed, and reused 5 times. Figure 10-16 The figures shown are high-performance liquid chromatography (HPLC) chromatograms before catalytic testing of the reaction solution, and after catalytic testing of the reaction solutions in Examples 1-3 and Comparative Examples 1-3, respectively. Figure 17-22 The figures shown are high-performance liquid chromatograms of the reaction solutions obtained after the catalysts of Examples 1-3 and Comparative Examples 1-3 were reused 5 times.
[0040] The results are shown in Table 1.
[0041] Table 1. Palladium loss rate, initial conversion rate, and conversion rate after 5 repetitions. As shown in Table 1, the catalyst supports of Examples 1-3 of the present invention have excellent active material immobilization effect and long-term stability, which is beneficial to improving catalytic conversion rate.
[0042] Compared to Example 1, Comparative Example 1 omitted the functionalized onion carbon and replaced the silane coupling agent KH590 with KH550. This resulted in increased palladium loss, decreased catalytic conversion, and significantly reduced cycle stability. This indicates that the introduction of onion carbon can enhance the anchoring effect of the support on the active component and improve catalytic performance. Comparative Example 2 used unfunctionalized onion carbon instead of functionalized onion carbon. While the palladium loss rate, conversion, and cycle stability were better than Comparative Example 1, they were still inferior to Example 1. This suggests that although unfunctionalized onion carbon can provide some physical support, the functionalized onion carbon can more effectively anchor the catalyst through chemical bonding, inhibiting catalyst migration and aggregation in the support, and synergistically improving catalytic performance.
[0043] Compared with Example 1, Comparative Example 3 omitted N-hydroxyethyliminodiacetic acid, resulting in the highest palladium loss rate, the worst conversion rate, and the worst cycle stability. This indicates that the chelation sites provided by N-hydroxyethyliminodiacetic acid are key to immobilizing the active component and maintaining high activity and long-term stability.
[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.
Claims
1. A method for preparing a modified activated carbon material for a catalyst support, characterized in that, Includes the following steps: (1) Add pretreated activated carbon and mercapto-containing silane coupling agent to an ethanol aqueous solution, stir to react, then add functionalized onion carbon and catalyst to continue the reaction, filter, wash and dry to obtain activated carbon loaded with onion carbon. (2) Under the action of an acidic catalyst, activated carbon loaded with onion carbon and N-hydroxyethylimine diacetic acid are reacted in N,N-dimethylformamide to obtain modified activated carbon material.
2. The method for preparing modified activated carbon material for catalyst support according to claim 1, characterized in that, The functionalized onion carbon mentioned in step (1) is prepared by the following process: (a) Add onion carbon to a mixed acid, disperse by ultrasonication, heat and stir, and wash by centrifugation to obtain pretreated onion carbon; (b) Under an ammonia atmosphere, the pretreated onion carbon was subjected to plasma treatment to obtain aminated onion carbon; (c) Aminated onion carbon, hydroxymalondialdehyde and sodium cyanoborohydride were added sequentially to dimethyl sulfoxide, stirred and reacted, and then separated, washed and dried to obtain functionalized onion carbon.
3. The method for preparing modified activated carbon material for catalyst support according to claim 2, characterized in that, The mixed acid in step (a) is composed of a 65% nitric acid solution and a 98% sulfuric acid solution in a volume ratio of 1:(2.8-3.2); the ratio of onion carbon to mixed acid is 1 g:(320-360) mL; the heating and stirring temperature is 70-80 ℃ and the time is 20-30 h.
4. The method for preparing modified activated carbon material for catalyst support according to claim 2, characterized in that, The plasma treatment in step (b) has a power of 150-200 W, an ammonia flow rate of 20-30 mL / min, a pressure of 2-5 kPa, and a time of 0.5-1 h.
5. The method for preparing modified activated carbon material for catalyst support according to claim 2, characterized in that, In step (c), the ratio of hydroxymalondialdehyde, aminated onion carbon, sodium cyanoborohydride, and dimethyl sulfoxide is 5 g: (0.5-0.6) g: (0.05-0.1) g: (95-100) mL; the stirring reaction time is 3-8 h.
6. The method for preparing modified activated carbon material for catalyst support according to claim 1, characterized in that, The pretreated activated carbon in step (1) is obtained by soaking activated carbon in a nitric acid solution; the mass fraction of the nitric acid solution is 1-5 wt%; the ratio of activated carbon to nitric acid solution is 1 g: (10-15) mL; the soaking temperature is 50-70 ℃ and the soaking time is 1-2 h.
7. The method for preparing modified activated carbon material for catalyst support according to claim 1, characterized in that, The mercapto-containing silane coupling agent mentioned in step (1) is KH590; the catalyst is p-toluenesulfonic acid; and the volume fraction of ethanol in the aqueous ethanol solution is 25-30%.
8. The method for preparing modified activated carbon material for catalyst support according to claim 1, characterized in that, In step (1), the ratio of the amount of pretreated activated carbon, mercapto-containing silane coupling agent, functionalized onion carbon, catalyst and ethanol aqueous solution is 10 g: (1-2) g: (0.25-0.5) g: (0.1-0.15) g: (80-160) mL; the temperature of the stirring reaction is 40-60 ℃ and the time is 0.5-1.5 h; the reaction continues for 1-2 h.
9. The method for preparing modified activated carbon material for catalyst support according to claim 1, characterized in that, The acid catalyst in step (2) is a concentrated sulfuric acid solution with a mass fraction of 98%; the ratio of the activated carbon supported onion carbon, N-hydroxyethylimine diacetic acid, acid catalyst and N,N-dimethylformamide is 10 g: (0.6-1.2) g: (0.5-1) mL: (50-80) mL; the reaction temperature is 80-100 ℃ and the time is 3-5 h.
10. Modified activated carbon material for catalyst support prepared by the preparation method according to any one of claims 1-9.