Preparation method of catalyst pd / lDH and application thereof in preparation of hydrogenated colophony from colophony

Abstract

The application discloses a preparation method of a catalyst Pd / LDH and application of the catalyst Pd / LDH in preparation of hydrogenated colophony from colophony. The catalyst Pd / LDH is prepared by using colophony as raw material, water and anhydrous ethanol as solvents and by adopting a hydrothermal method to synthesize a two-dimensional transition metal hydroxide carrier to load palladium. The catalyst Pd / LDH provided by the application shows excellent catalytic activity and product selectivity for colophony ethanol phase hydrogenation reaction. The excellent catalytic performance is due to the fact that the catalyst carrier is synthesized by using the hydrothermal method, and the carrier has a higher nitrogen content because of the addition of urea, so that more effective metal coordination anchoring points are provided for the carrier, which is favorable to improve the dispersity of metal nanoparticles and increase the amount of active components. In addition, experimental data prove that the Pd / LDH catalyst prepared by the application has higher catalytic selectivity for products.

Description

Technical Field

[0001] This invention belongs to the field of rosin hydrogenation to prepare hydrogenated rosin, and specifically relates to the preparation method of the catalyst Pd / LDH and its application in the preparation of hydrogenated rosin by rosin hydrogenation. Background Technology

[0002] Rosin is a natural resin extracted from pine wood. Its color ranges from light yellow to reddish-brown, and it has extremely high transparency and thermoplasticity. Rosin is composed of various components, the main one being resin acids, along with small amounts of fatty acids and neutral substances. Analysis shows that in typical rosin, the content of resin acids is between 85.6% and 88.7%, the content of fatty acids is between 2.5% and 5.4%, and the content of neutral substances is between 5.2% and 7.6%. The acidic component, rosin acid, is also a mixture, mainly composed of isomerized rosin acid (40-60%) and piratic acid (9-27%). Rosin and its derivatives have traditionally been used in the production of adhesive pacifiers, facial tissues, etc.

[0003] Because rosin molecules contain unsaturated conjugated double bonds, they are highly sensitive to oxygen and readily oxidize when exposed to oxygen-containing atmospheres, leading to a decline in material properties. Therefore, various methods, such as isomerization, disproportionation, hydrogenation, maleization, and esterification, are frequently used to modify rosin and create derivatives to increase its practical value. Among these derivatives, hydrogenated rosin is an important modifying material, produced through a hydrogenation reaction. Hydrogenated rosin possesses excellent antioxidant properties, low brittleness, and high thermal stability, and is non-toxic. Therefore, it has a wide range of industrial applications, including adhesives, synthetic rubber, coatings, inks, paper, electronics, food, welding, and pharmaceuticals.

[0004] Currently, catalysts used in the hydrogenation of rosin to produce hydrogenated rosin are mainly divided into two categories based on their active sites: noble metal catalysts and non-noble metal catalysts. Catalysts with noble metals as the active component have made good progress in the hydrogenation of rosin. However, noble metals also have some unavoidable drawbacks, such as high price, relatively limited availability, and instability, which greatly increases the cost of their application in industrial production. Non-noble metal catalysts, on the other hand, have the disadvantages of requiring sophisticated reaction equipment and harsh reaction conditions. Furthermore, the compatibility and synergy between the catalyst support and the active site play a crucial role in the hydrogenation of rosin. Catalysts obtained by combining different catalyst supports and active sites exhibit unpredictable catalytic activity and product selectivity in the hydrogenation of rosin. Summary of the Invention

[0005] To improve rosin conversion rate and achieve highly selective preparation of hydrogenated rosin to obtain high-quality premium rosin, the present invention aims to provide a method for preparing the catalyst Pd / LDH and its application in the hydrogenation of rosin to prepare hydrogenated rosin.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: The application of catalyst Pd / LDH in the preparation of hydrogenated rosin by hydrogenation of rosin, wherein the catalyst Pd / LDH is a two-dimensional nanosheet metal hydroxide LDH as a support, metal Pd as the active component, the loading of metal Pd is 0.5-2%, and the metal in the support LDH is at least one of Ce, Fe, and Ni.

[0007] Furthermore, the preparation method of the catalyst Pd / LDH is as follows: at least one of Ce source, Fe source, and Ni source is used as the metal source raw material, and urea is used as the homogeneous precipitant and morphology modifier to synthesize the LDH support by hydrothermal method; then, Pd nanoparticles are loaded onto the LDH support by impregnation-hydrogen reduction method to obtain the catalyst Pd / LDH.

[0008] Furthermore, the method for preparing the LDH carrier includes: S1: Dissolve the metal source and urea in water, load the mixture into a reaction vessel, seal the reaction vessel, and place it in an oven for hydrothermal reaction; the metal source is at least one of Ce source, Fe source, and Ni source; S2: After the reaction is complete, centrifuge, dry, grind, and calcine to obtain the LDH support.

[0009] Furthermore, in step S1, the molar ratio of the metal source to the mass of urea is 1.5-2 mmol:1g, the temperature of the hydrothermal reaction is 150-180℃, and the reaction time is 5-10h.

[0010] Furthermore, in step S2, the calcination is carried out in an air atmosphere, the calcination temperature is 350-400℃, and the calcination time is 2-4 hours.

[0011] Furthermore, the specific steps for loading Pd nanoparticles onto the LDH support using the impregnation-hydrogen reduction method are as follows: Step 1: Disperse the LDH support in water, add the Pd source, and stir and soak at 60-85℃ for 5-20 hours; Step 2: Subsequently, the mixture was cooled to room temperature, filtered, dried, ground, and then reduced at high temperature in a hydrogen-argon mixed atmosphere to finally obtain the catalyst Pd / LDH.

[0012] Further, in step 1, the mass of Pd element in the Pd source is 0.5-2% of the mass of LDH support; in step 2, the hydrogen gas fraction in the hydrogen-argon mixed atmosphere is 10-20%, the high-temperature reduction temperature is 300-400℃, and the reduction time is 2-5h.

[0013] Furthermore, the application method is as follows: rosin raw material and catalyst Pd / LDH are added to the reaction solvent, the mixture is transferred to the reaction vessel, and a catalytic hydrogenation reaction is carried out under a hydrogen atmosphere to generate hydrogenated rosin; after the reaction is completed, the catalyst and product can be separated after standing.

[0014] Furthermore, the mass of the catalyst Pd / LDH is 4-6% of the mass of the rosin raw material, and the reaction solvent is at least one of ethanol and water.

[0015] Furthermore, the reaction temperature of the catalytic hydrogenation reaction is 160-170℃, and the hydrogen pressure is 2-4MPa.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) This invention utilizes a hydrothermal method to prepare a rhombic nanosheet structured LDH support. Palladium nanoparticles are then loaded onto the support via impregnation-hydrogen reduction to form a stable nanocatalyst, Pd / LDH. The Pd / LDH catalyst provided by this invention exhibits excellent catalytic activity and product selectivity for the hydrogenation reaction of rosin and ethanol. The excellent catalytic performance is due to the hydrothermal synthesis of the catalyst support, which, with the addition of urea, has a high nitrogen content, providing more effective metal coordination anchoring sites, thus improving the dispersibility of the metal nanoparticles and increasing the number of active components. Furthermore, experimental data demonstrate that the Pd / LDH catalyst prepared in this invention exhibits high catalytic selectivity for the product.

[0017] (2) In the catalytic hydrogenation reaction, the Pd / LDH solid catalyst-rosin ethanol phase-hydrogen gas provided by the present invention forms a three-phase interface, which reduces the mass transfer resistance and is conducive to the reaction. This allows the catalytic hydrogenation reaction to be carried out under mild conditions. The mild reaction conditions enable the catalyst to have higher catalytic efficiency and product selectivity for rosin.

[0018] (3) The experimental results show that the catalyst provided by the present invention effectively improves the rosin conversion rate when used for catalytic hydrogenation of rosin, with the rosin conversion rate reaching over 90% and the selectivity of hydrogenated rosin reaching 70%; thus achieving the high-quality premium rosin grade. From the above technical solutions, it can be seen that the preparation method described in the present invention can effectively improve the rosin conversion rate, yields a highly selective product, has a simple preparation method, uses safe reagents, and is beneficial for industrial production. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope image of the LDH carrier obtained in Example 1; Figure 2 This is a scanning electron microscope image of the catalyst Pd / LDH-CeO2 obtained in Example 1. Detailed Implementation

[0020] This invention discloses a method for preparing the catalyst Pd / LDH and its application in the hydrogenation of rosin to prepare hydrogenated rosin. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0021] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0022] Example 1: Preparation and Catalytic Application of Pd / LDH Catalyst 1) Preparation of two-dimensional hydroxide supports: 5 mmol of cerium nitrate hexahydrate and 3 g of urea were dispersed in 100 ml of deionized water and sonicated to form a clear solution. This solution was placed in a high-pressure reactor with a polytetrafluoroethylene liner. After sealing the reactor, it was transferred to an oven, and a programmed temperature rise was set, increasing the temperature to 160 °C at a rate of 5 °C / min. The reaction was maintained at 160 °C for 8 hours. After the reaction, the solid was obtained by centrifugation and placed in an oven to stand until completely dry. The dried solid was then ground and transferred to a ceramic boat, placed in a muffle furnace, and calcined at high temperature in air atmosphere. The temperature was increased to 400 °C at a rate of 5 °C / min and maintained at 400 °C for 4 hours. The resulting white powder is the LDH-CeO2 support, or simply LDH support.

[0023] 2) Preparation of Pd / LDH catalyst supported on Pd: Weigh 500 mg of the LDH support prepared in step 1) and disperse it in 25 mL of deionized water. Then, accurately weigh 13.82 mg of sodium tetrachloropalladium (containing approximately 5 mg of Pd) and add it to dissolve. Stir the mixture magnetically at 600 rpm for 6 h at 85 °C. After cooling, filter the mixture and dry the resulting solid in an oven. After grinding, transfer the dried solid to a ceramic boat and place it in a tube furnace with a hydrogen (15% by volume) and argon (85% by volume) mixed atmosphere for high-temperature reduction. The temperature is increased to 400 °C at a heating rate of 5 °C / min and maintained at 400 °C for 4 h to finally obtain the Pd-supported catalyst Pd / LDH-CeO2.

[0024] Figure 1 This is a scanning electron microscope (SEM) image of the LDH carrier obtained in Example 1. From... Figure 1 As can be seen from the data, the prepared LDH support has a layered structure.

[0025] Figure 2 This is a scanning electron microscope (SEM) image of the Pd / LDH-CeO2 catalyst obtained in Example 1. From... Figure 2 It can be seen that Pd nanoparticles are loaded on the surface.

[0026] An application experiment was conducted to prepare hydrogenated rosin via rosin hydrogenation. The experimental procedure was as follows: 500 mg of rosin and 25 mg of the catalyst Pd / LDH-CeO2 prepared in Example 1 were weighed and added to a reaction vessel, along with 25 ml of anhydrous ethanol. The reaction vessel was sealed, and the air inside was first purged four times with 1 MPa of H2. Then, 3 MPa of H2 was introduced into the reaction vessel. The reaction vessel was repeatedly checked for leaks. After confirming that there were no leaks, the reaction vessel was placed in an external electric heating mantle, and the temperature sensing probe and power supply were connected. After turning on the switch and setting the program, the temperature was raised to 160℃ for catalytic hydrogenation. The mechanical stirrer was turned on and maintained at 500 rpm for 8 hours. After the reaction was completed, the reaction vessel was cooled, and the liquid inside was transferred to centrifuge tubes. The mixture was allowed to stand to separate into layers, and the solution was filtered and analyzed by gas chromatography-mass spectrometry. The total conversion rate of rosin was 90%, and the selectivity of hydrogenated rosin was 87%, which meets the standards for high-grade hydrogenated rosin.

[0027] Example 2: Application Experiment of Rosin Hydrogenation to Prepare Hydrogenated Rosin The experimental steps of Example 2 were repeated in Example 1, except that the temperature of the catalytic hydrogenation reaction was changed from 160°C to 170°C and the reaction was stirred at 170°C for 8 hours. All other conditions remained the same. The final experimental results were: the total conversion rate of rosin was 88% and the selectivity of hydrogenated rosin was 85%, which is enough to reach the level of premium hydrogenated rosin.

[0028] Example 3: Application Experiment of Rosin Hydrogenation to Prepare Hydrogenated Rosin The experimental steps of Example 3 were repeated in Example 1, except that the temperature of the catalytic hydrogenation reaction was changed from 160°C to 180°C and the reaction was stirred at 180°C for 8 hours. All other conditions remained the same. The final experimental results were: the total conversion rate of rosin was 88% and the selectivity of hydrogenated rosin was 80%, which is enough to reach the level of premium hydrogenated rosin.

[0029] The experimental results of Examples 1-3 show that the catalytic efficiency remains basically unchanged when the temperature of the rosin hydrogenation reaction is too high. Considering the safety and cost savings in actual production, the effective catalytic temperature of this catalyst is selected to be 160-170℃.

[0030] Comparative Example 1: Preparation and Application of Catalysts on Rod-shaped CeO2 Support Weigh 5 mmol of cerium nitrate hexahydrate and 3 g of sodium hydroxide, disperse them in 100 ml of deionized water, and sonicate to form a clear solution. Place this solution into a high-pressure reactor with a polytetrafluoroethylene liner. After sealing the reactor, transfer it to an oven and set a programmed temperature increase, raising the temperature to 100 °C at a rate of 5 °C / min, and holding at 100 °C for 24 h. After the reaction, centrifuge to obtain the solid, and place the solid in an oven to stand until completely dry. Grind the dried solid and transfer it to a porcelain boat, then place it in a muffle furnace for high-temperature calcination in air atmosphere, raising the temperature to 400 °C at a rate of 5 °C / min, and holding at 400 °C for 6 h. The resulting yellow powder is the CeO2 support.

[0031] The preparation method of the catalyst Pd / CeO2 in Comparative Example 1 is the same as step 2 of Example 1, except that "in step 2), the LDH support is replaced with the same mass of CeO2 support of Comparative Example 1", and the rest of the steps remain unchanged, and finally the Pd-supported catalyst Pd / CeO2 is obtained.

[0032] The catalyst Pd / CeO2 prepared in Comparative Example 1 was used in the application experiment of rosin hydrogenation to prepare hydrogenated rosin. The experimental procedure was the same as in Example 1. The reaction results were: the total conversion rate of rosin was 84%, and the selectivity of hydrogenated rosin was 81%.

[0033] Comparative Example 2: Preparation and Application of Catalysts Supported by Al2O3 The preparation steps of the Al2O3 support in Comparative Example 2 were the same as those in Comparative Example 1, except that "cerium nitrate hexahydrate was replaced with an equal molar amount of aluminum nitrate", and the other conditions remained unchanged, and the Al2O3 support was finally obtained.

[0034] The preparation method of the Pd / Al2O3 catalyst in Comparative Example 2 is the same as step 2 of Example 1, except that "in step 2), the LDH support is replaced with the same mass of Al2O3 support of Comparative Example 2", and the rest of the steps remain unchanged, and finally the Pd-supported catalyst Pd / Al2O3 is obtained.

[0035] The catalyst Pd / Al2O3 prepared in Comparative Example 2 was used in the application experiment of rosin hydrogenation to prepare hydrogenated rosin. The experimental procedure was the same as in Example 1. The reaction results were: the total conversion rate of rosin was 86% and the selectivity of hydrogenated rosin was 82%.

[0036] Comparative Example 3: Preparation and Catalytic Application of Pd / LDH(Ni) Catalyst The preparation steps of the Pd / LDH(Ni) catalyst in Comparative Example 3 were repeated in Example 1, except that in the preparation step of the support in "step 1), cerium nitrate hexahydrate was replaced with an equal molar amount of nickel nitrate", and the rest of the steps remained unchanged, and the Pd-supported catalyst Pd / LDH(Ni) was finally obtained.

[0037] The catalyst Pd / LDH(Ni) prepared in Comparative Example 3 was used in the application experiment of rosin hydrogenation to prepare hydrogenated rosin. The experimental procedure was the same as in Example 1. The reaction results were: the total conversion rate of rosin was 80% and the selectivity of hydrogenated rosin was 82%.

[0038] Comparative Example 4: Preparation and Catalytic Application of Pd / LDH(Fe) Catalyst The preparation steps of the Pd / LDH(Fe) catalyst in Comparative Example 4 were repeated in Example 1, except that in the preparation step of the support in "step 1), cerium nitrate hexahydrate was replaced with an equal molar amount of iron nitrate", and the rest of the steps remained unchanged, and the Pd-supported catalyst Pd / LDH(Fe) was finally obtained.

[0039] The catalyst Pd / LDH(Fe) prepared in Comparative Example 4 was used in the application experiment of rosin hydrogenation to prepare hydrogenated rosin. The experimental procedure was the same as in Example 1. The reaction results were: the total conversion rate of rosin was 82% and the selectivity of hydrogenated rosin was 83%.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of catalyst Pd / LDH in the hydrogenation of rosin to prepare hydrogenated rosin, characterized in that, The catalyst Pd / LDH uses two-dimensional nanosheet metal hydroxide LDH as a support, metal Pd as the active component, and the loading of metal Pd is 0.5-2%. The metal in the support LDH is at least one of Ce, Fe, and Ni.

2. The application as described in claim 1, characterized in that, The catalyst Pd / LDH is prepared by using at least one of Ce, Fe, and Ni as the metal source material, and urea as the homogeneous precipitant and morphology modifier to synthesize the LDH support via a hydrothermal method; then, Pd nanoparticles are loaded onto the LDH support by an impregnation-hydrogen reduction method to obtain the catalyst Pd / LDH.

3. The application as described in claim 2, characterized in that, The method for preparing the LDH carrier includes: S1: Dissolve the metal source and urea in water, load the mixture into a reaction vessel, seal the reaction vessel, and place it in an oven for hydrothermal reaction; the metal source is at least one of Ce source, Fe source, and Ni source; S2: After the reaction is complete, centrifuge, dry, grind, and calcine to obtain the LDH support.

4. The application as described in claim 3, characterized in that, In step S1, the molar ratio of the metal source to the mass of urea is 1.5-2 mmol:1g, the temperature of the hydrothermal reaction is 150-180℃, and the reaction time is 5-10h.

5. The application as described in claim 3, characterized in that, In step S2, calcination is carried out in an air atmosphere at a temperature of 350-400℃ for 2-4 hours.

6. The application as described in claim 2, characterized in that, The specific steps for loading Pd nanoparticles onto the LDH support using the impregnation-hydrogen reduction method are as follows: Step 1: Disperse the LDH support in water, add the Pd source, and stir and soak at 60-85℃ for 5-20 hours; Step 2: Subsequently, the mixture was cooled to room temperature, filtered, dried, ground, and then reduced at high temperature in a hydrogen-argon mixed atmosphere to finally obtain the catalyst Pd / LDH.

7. The application as described in claim 6, characterized in that, In step 1, the mass of Pd element in the Pd source is 0.5-2% of the mass of LDH support; in step 2, the hydrogen gas fraction in the hydrogen-argon mixed atmosphere is 10-20%, the high-temperature reduction temperature is 300-400℃, and the reduction time is 2-5h.

8. The application as described in claim 1, characterized in that, The application method is as follows: rosin raw material and catalyst Pd / LDH are added to the reaction solvent, the mixture is transferred to the reaction vessel, and a catalytic hydrogenation reaction is carried out under a hydrogen atmosphere to generate hydrogenated rosin.

9. The application as described in claim 8, characterized in that, The mass of the catalyst Pd / LDH is 4-6% of the mass of the rosin raw material, and the reaction solvent is at least one of ethanol and water.

10. The application as described in claim 8, characterized in that, The reaction temperature of the catalytic hydrogenation reaction is 160-170℃, and the hydrogen pressure is 2-4MPa.

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