Hydrogenated rosin catalyst and preparation method thereof

Abstract

The invention discloses a hydrogenated rosin catalyst and a preparation method thereof, and relates to the technical field of catalyst preparation. The preparation method of the catalyst comprises the following steps: firstly, pretreating the activated carbon by adopting a carbon nano tube to obtain pretreated activated carbon; soaking the pretreated activated carbon in a nitric acid solution to obtain acid-treated activated carbon; soaking the acid-treated activated carbon in a nitrogen-containing compound solution, and carrying out heating reaction in an inert atmosphere to obtain nitrogen-doped activated carbon; and reacting the nitrogen-doped activated carbon with a palladium precursor and a reducing agent, filtering and drying to obtain the nitrogen-doped activated carbon catalyst. The activated carbon is pretreated by adopting the carbon nano tube, and the carbon carrier is modified with the nitrogen source, so that the catalyst still has very high catalytic activity and reusability after repeated circulating rosin hydrogenation, and has a relatively high application value.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and in particular to a hydrogenated rosin catalyst and its preparation method. Background Technology

[0002] Rosin is a complex mixture whose main component is abietic acid (C12- ... 19 H 29 Because abietic acid contains conjugated double bonds, it is easily oxidized by oxygen, causing rosin to darken in color, increase in hydroxyl value, become brittle, have poor thermal stability, and suffer from quality degradation, thus limiting its applications. Catalytic hydrogenation is generally used to modify the conjugated double bond structure of abietic acid, obtaining hydrogenated rosin to improve its stability. Hydrogenated rosin mainly contains dihydroabietic acid and tetrahydroabietic acid, and has characteristics such as good antioxidant properties, low brittleness, high thermal stability, and light color, thus it is widely used in adhesives, thickeners, fluxes, rubber, and coatings industries.

[0003] Currently, the industrial preparation of hydrogenated rosin mainly uses palladium-carbon noble metal catalysts. These catalysts offer advantages such as high conversion rate, good selectivity, strong resistance to poisoning, and easy recovery in rosin catalytic reactions. However, these catalysts have the following problems: after repeated use, the active palladium particles are lost or sintered and aggregated, reducing the number of active sites and leading to poor stability and easy deactivation; the activated carbon support deforms and collapses after repeated use, burying the active palladium particles, resulting in fewer catalyst reuse cycles and easy deactivation.

[0004] Therefore, there is an urgent need to develop a catalyst that still maintains high stability and activity after repeated use. Summary of the Invention

[0005] To address the above shortcomings, this invention provides a hydrogenated rosin catalyst and its preparation method, solving the problems of low stability and easy deactivation of existing hydrogenated rosin catalysts. The specific technical solution is as follows: A method for preparing a hydrogenated rosin catalyst includes the following steps: S1. Soak activated carbon powder in nitric acid solution for 2-3 hours, wash with deionized water until neutral, and dry at 100-110℃ to constant weight to obtain acid-treated activated carbon. S2. The acid-treated activated carbon is soaked in a nitrogen-containing compound solution and stirred for 3-5 hours. It is then dried at 80-100°C to constant weight. In an inert atmosphere (argon or nitrogen), it is heated to 600-800°C at a heating rate of 2-5°C / min and held for 1-2 hours. It is then cooled to room temperature to obtain nitrogen-doped activated carbon. S3. Disperse the nitrogen-doped activated carbon in deionized water to form a slurry. Adjust the pH of the slurry to 10-11, then slowly add a palladium precursor solution with a concentration of 0.5-1.9 mg / L. Stir at a constant temperature of 30-50°C for 2-4 hours. Then slowly add a reducing agent solution with a concentration of 2-4 g / L. Continue stirring for 2-3 hours. Filter, wash with deionized water, and vacuum dry at 60-80°C for 8-10 hours to obtain the hydrogenated rosin catalyst.

[0006] Further, in step S1, the activated carbon is pretreated as follows before acid treatment: the activated carbon is added to a carbon nanotube solution and ball-milled at 200-400 rpm for 2-6 hours, and then freeze-dried for 20-24 hours; the mass ratio of the activated carbon to the carbon nanotubes is 100:(5-10).

[0007] Further, the carbon nanotube solution is prepared by mixing carbon nanotubes, dispersant and water in a mass ratio of (5-15):(2-7):100 and ultrasonically dispersing for 30-40 minutes; the dispersant is polyvinylpyrrolidone or sodium dodecyl sulfate.

[0008] Furthermore, in step S1, the mass concentration of the nitric acid solution is 50-60%.

[0009] Further, in step S2, the nitrogen-containing compound is urea or polyaniline; the mass concentration of the nitrogen-containing compound solution is 20-40%.

[0010] Further, in step S3, the mass-to-volume ratio of the nitrogen-doped activated carbon to deionized water is (1-10) g: 50 mL.

[0011] Further, in step S3, the palladium precursor is dichlorotetraamminepalladium or palladium nitrate.

[0012] Further, in step S3, the reducing agent is sodium borohydride, hydrazine hydrate, or ethylene glycol.

[0013] Further, in step S3, the palladium precursor is 1-4 wt% of nitrogen-doped activated carbon; the molar ratio of the reducing agent to palladium is (5-10):1.

[0014] The present invention also provides a hydrogenated rosin catalyst prepared by the above preparation method.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention modifies the electronic properties of a carbon support by modifying it with nitrogen sources, enhancing the interaction between palladium and carbon. This allows palladium particles to be stably anchored on the carbon support, effectively preventing the loss or aggregation of palladium particles after repeated use and improving activity. Simultaneously, pretreatment of activated carbon with carbon nanotubes enhances the rigidity of the carbon support framework, effectively preventing deformation or collapse of the activated carbon support after repeated use, thus improving activity and lifespan. Compared with traditional catalysts, the catalyst prepared by this invention retains high catalytic activity even after multiple cycles of rosin hydrogenation. Testing showed that after seven cycles, the rosin conversion rate remained above 95%, and the dihydroabsic acid selectivity remained above 90%, demonstrating excellent stability and reusability. Detailed Implementation

[0016] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0017] Example 1 A method for preparing a hydrogenated rosin catalyst includes the following steps: S1. Add activated carbon to the carbon nanotube solution, ball mill at 200 rpm for 6 hours, and freeze dry for 20 hours to obtain pretreated activated carbon; the mass ratio of activated carbon to carbon nanotubes is 100:5; the carbon nanotube solution is prepared by mixing carbon nanotubes, polyvinylpyrrolidone and water at a mass ratio of 5:2:100 and ultrasonically dispersing for 30 minutes. Pretreated activated carbon powder was soaked in a 50% nitric acid solution for 2 hours, washed with deionized water until neutral, and dried at 100°C to constant weight to obtain acid-treated activated carbon. Adding nitric acid solution can remove surface dust and some ash, and introduce oxygen-containing groups such as carboxyl and hydroxyl groups on the surface of activated carbon. S2. The acid-treated activated carbon is soaked in a 20% urea solution and stirred for 3 hours. It is then dried at 80°C to constant weight. At this point, the nitrogen source is adsorbed on the surface of the activated carbon. Then, in an argon atmosphere, the carbon is heated to 600°C at a heating rate of 2°C / min and held for 2 hours. After cooling to room temperature, the adsorbed nitrogen source decomposes and reacts with the functional groups on the surface of the activated carbon, fixing the nitrogen atoms on the carbon framework to obtain nitrogen-doped activated carbon. S3. Disperse 1g of nitrogen-doped activated carbon in 50mL of deionized water to form a slurry. After adjusting the pH of the slurry to 10, slowly add 20mL of a 0.5g / L dichlorotetraamminepalladium solution. Stir at 30℃ for 4h. At this time, palladium cations will be selectively and tightly adsorbed around the negatively charged nitrogen-doped sites. Then slowly add a 2g / L sodium borohydride solution with a molar ratio of sodium borohydride to palladium of 5:1. Continue stirring for 2h, filter, wash with deionized water, and vacuum dry at 60℃ for 10h to obtain the hydrogenated rosin catalyst.

[0018] Example 2 A method for preparing a hydrogenated rosin catalyst includes the following steps: S1. Add activated carbon to the carbon nanotube solution, ball mill at 400 rpm for 2 hours, and freeze dry for 24 hours to obtain pretreated activated carbon; the mass ratio of activated carbon to carbon nanotubes is 100:10; the carbon nanotube solution is prepared by mixing carbon nanotubes, sodium dodecyl sulfate and water at a mass ratio of 15:7:100 and ultrasonically dispersing for 40 minutes. Pretreated activated carbon powder was soaked in a 60% nitric acid solution for 3 hours, washed with deionized water until neutral, and dried at 110°C to constant weight to obtain acid-treated activated carbon. Adding nitric acid solution can remove surface dust and some ash, and introduce oxygen-containing groups such as carboxyl and hydroxyl groups on the surface of activated carbon. S2. The acid-treated activated carbon is soaked in a 40% polyaniline solution and stirred for 5 hours. It is then dried at 100°C to constant weight. At this point, the nitrogen source is adsorbed on the surface of the activated carbon. Then, in a nitrogen atmosphere, the carbon is heated to 800°C at a heating rate of 5°C / min and held for 1 hour. After cooling to room temperature, the adsorbed nitrogen source decomposes and reacts with the functional groups on the surface of the activated carbon, fixing nitrogen atoms on the carbon framework to obtain nitrogen-doped activated carbon. S3. Disperse 10g of nitrogen-doped activated carbon in 50mL of deionized water to form a slurry. After adjusting the pH of the slurry to 11, slowly add 25mL of palladium nitrate solution with a concentration of 1.5g / L. Stir at 50℃ for 2h. At this time, palladium cations will be selectively and tightly adsorbed around the negatively charged nitrogen-doped sites. Then slowly add hydrazine hydrate solution with a concentration of 4g / L. The molar ratio of hydrazine hydrate to palladium is 10:1. Continue stirring for 3h. Filter, wash with deionized water, and vacuum dry at 80℃ for 8h to obtain the hydrogenated rosin catalyst.

[0019] Example 3 A method for preparing a hydrogenated rosin catalyst includes the following steps: S1. Add activated carbon to the carbon nanotube solution, ball mill at 300 rpm for 4 hours, and freeze dry for 22 hours to obtain pretreated activated carbon; the mass ratio of activated carbon to carbon nanotubes is 100:8; the carbon nanotube solution is prepared by mixing carbon nanotubes, polyvinylpyrrolidone and water at a mass ratio of 10:6:100 and ultrasonically dispersing for 35 minutes. Pretreated activated carbon powder was soaked in a 55% nitric acid solution for 3 hours, washed with deionized water until neutral, and dried at 110°C to constant weight to obtain acid-treated activated carbon. Adding nitric acid solution can remove surface dust and some ash, and introduce oxygen-containing groups such as carboxyl and hydroxyl groups on the surface of activated carbon. S2. The acid-treated activated carbon is soaked in a 30% urea solution and stirred for 4 hours. It is then dried at 100°C to constant weight. At this point, the nitrogen source is adsorbed on the surface of the activated carbon. Then, in an argon atmosphere, the carbon is heated to 700°C at a heating rate of 4°C / min and held for 1 hour. After cooling to room temperature, the adsorbed nitrogen source decomposes and reacts with the functional groups on the surface of the activated carbon, fixing the nitrogen atoms on the carbon framework to obtain nitrogen-doped activated carbon. S3. Disperse 5g of nitrogen-doped activated carbon in 50mL of deionized water to form a slurry. Adjust the pH of the slurry to 10-11, then slowly add 20mL of a 1g / L dichlorotetraamminepalladium solution. Stir at 40℃ for 3h. At this time, palladium cations will be selectively and tightly adsorbed around the negatively charged nitrogen-doped sites. Then slowly add a 3g / L sodium borohydride solution with a molar ratio of sodium borohydride to palladium of 7:1. Continue stirring for 3h, filter, wash with deionized water, and vacuum dry at 70℃ for 9h to obtain the hydrogenated rosin catalyst.

[0020] Comparative Example 1: In step S1, activated carbon was not added to carbon nanotubes for pretreatment, and the other steps were the same as in Example 1.

[0021] Comparative Example 2: Steps S1 and S2 were omitted, i.e., activated carbon was used instead of nitrogen-doped activated carbon for the reaction, and the other steps were the same as in Example 1.

[0022] Comparative Example 3: A commercially available palladium-on-carbon catalyst was used, purchased from Wuhan Kemic Biomedical Technology Co., Ltd.

[0023] The same batch of rosin was hydrogenated using the catalysts prepared in Examples 1, 2, 3, Comparative Examples 1 and 2, and the catalyst in Comparative Example 3, respectively.

[0024] The rosin hydrogenation method is as follows: 10g of rosin is dissolved in 15g of No. 200 solvent oil and placed in a high-pressure reactor. Then, 0.5g of catalyst is added, hydrogen is introduced, and the reactor is purged four times to completely replace the original air. The hydrogenation reaction is carried out at 150℃ with a hydrogen pressure of 5MPa and a stirring speed of 600r / min. After reacting for 1 hour, the mixture is cooled to room temperature, allowed to stand and separate into layers, and the catalyst and product are separated. The separated catalyst is reused. The above hydrogenation steps are repeated 7 times. The gas chromatography analysis results of the first and seventh products are detected. The rosin conversion rate and dihydroabietic acid selectivity of the catalyst used in the first and seventh applications are calculated. The rosin conversion rate and dihydroabietic acid selectivity of the catalyst used in the seventh application are calculated. The results are shown in Table 1. A high rosin conversion rate indicates a complete reaction, and a high dihydroabietic acid selectivity indicates a good hydrogenation effect and excellent hydrogenated rosin quality.

[0025] Table 1. Effects of each catalyst group Table 1 shows that the catalyst prepared by the method of the present invention still has high catalytic activity after multiple cycles of rosin hydrogenation. After testing, the rosin conversion rate can still reach more than 95% and the dihydroabsic acid selectivity can still be maintained at more than 90% after 7 cycles, which shows good stability and reusability.

[0026] The data comparison between Example 1 and Comparative Example 1 shows that the pretreatment of activated carbon with carbon nanotubes in this invention can enable the catalyst to maintain a high conversion rate and selectivity after being reused 7 times. This indicates that the pretreatment of activated carbon with carbon nanotubes can enhance the rigidity of the carbon support skeleton, effectively prevent the activated carbon support from deforming or collapsing after repeated use, and improve the activity and lifespan.

[0027] The data comparison between Example 1 and Comparative Example 2 shows that the nitrogen doping treatment of activated carbon in this invention enables the catalyst to maintain a high conversion rate and selectivity after being reused 7 times. This indicates that modifying the carbon support with nitrogen sources changes the electronic properties of the carbon support surface, enhances the interaction between palladium and carbon, and enables palladium particles to be stably anchored on the carbon support. This effectively prevents the loss or aggregation of palladium particles after multiple uses of the catalyst, thereby improving the activity.

[0028] A comparison of data from Example 1 and Comparative Example 3 shows that the present invention is more stable than existing catalysts.

[0029] In summary, this invention, by pretreating activated carbon with carbon nanotubes and modifying the carbon support with nitrogen sources, enables the catalyst to maintain high catalytic activity and reusability after multiple cycles of rosin hydrogenation, thus possessing significant application value.

[0030] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing a hydrogenated rosin catalyst, characterized in that, Includes the following steps: S1. Soak activated carbon powder in nitric acid solution, wash with deionized water until neutral, and dry to obtain acid-treated activated carbon. S2. The acid-treated activated carbon is soaked in a nitrogen-containing compound solution, stirred, dried, and then heated to 600-800℃ in an inert atmosphere for 1-2 hours, and then cooled to room temperature to obtain nitrogen-doped activated carbon. S3. Disperse the nitrogen-doped activated carbon in deionized water to form a slurry. Adjust the pH of the slurry to 10-11, then slowly add a palladium precursor solution with a concentration of 0.5-1.9 mg / L, stir at a constant temperature, and then slowly add a reducing agent solution with a concentration of 2-4 g / L. Continue stirring, filter, wash with deionized water, and vacuum dry to obtain the hydrogenated rosin catalyst.

2. The method for preparing a hydrogenated rosin catalyst according to claim 1, characterized in that, In step S1, the activated carbon is pretreated as follows before acid treatment: the activated carbon is added to a carbon nanotube solution and ball-milled at 200-400 rpm for 2-6 hours, and then freeze-dried for 20-24 hours; the mass ratio of activated carbon to carbon nanotubes is 100:(5-10).

3. The method for preparing a hydrogenated rosin catalyst according to claim 2, characterized in that, The carbon nanotube solution is prepared by mixing carbon nanotubes, dispersant and water in a mass ratio of (5-15):(2-7):100 and ultrasonically dispersing for 30-40 minutes. The dispersant is polyvinylpyrrolidone or sodium dodecyl sulfate.

4. The method for preparing a hydrogenated rosin catalyst according to claim 1, characterized in that, In step S1, the mass concentration of the nitric acid solution is 50-60%.

5. The method for preparing a hydrogenated rosin catalyst according to claim 1, characterized in that, In step S2, the nitrogen-containing compound is urea or polyaniline; the mass concentration of the nitrogen-containing compound solution is 20-40%.

6. The method for preparing a hydrogenated rosin catalyst according to claim 1, characterized in that, In step S3, the mass-to-volume ratio of the nitrogen-doped activated carbon to deionized water is (1-10) g: 50 mL.

7. The method for preparing a hydrogenated rosin catalyst according to claim 1, characterized in that, In step S3, the palladium precursor is dichlorotetraamminepalladium or palladium nitrate.

8. The method for preparing a hydrogenated rosin catalyst according to claim 1, characterized in that, In step S3, the reducing agent is sodium borohydride, hydrazine hydrate, or ethylene glycol.

9. The method for preparing a hydrogenated rosin catalyst according to claim 1, characterized in that, In step S3, the palladium precursor is 1-4 wt% of nitrogen-doped activated carbon; the molar ratio of the reducing agent to palladium is (5-10):

1.

10. A hydrogenated rosin catalyst prepared by the method according to any one of claims 1-8.

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