A catalyst for squalene catalytic hydrogenation reaction under solvent-free condition and a preparation method thereof

Abstract

The application discloses a preparation method of a cerium oxide supported palladium catalyst and application of the catalyst in a solvent-free catalytic hydrogenation reaction of squalene, and belongs to the field of catalyst preparation and application. The catalyst takes cerium oxide as a carrier, and palladium is loaded through a deposition precipitation method to form a high-dispersion cerium oxide supported palladium catalytic system. The synergistic effect between the cerium oxide and the palladium significantly improves the hydrogenation efficiency and selectivity of the catalyst, and the catalyst is suitable for the catalytic hydrogenation reaction of squalene under a solvent-free condition. Compared with a traditional Pd / C catalyst, the prepared catalyst has higher activity, and the preparation method is simple, low in cost, and capable of efficiently catalyzing the hydrogenation of squalene under a solvent-free condition.

Description

Technical Field

[0001] This invention relates to a catalyst for the catalytic hydrogenation of squalene and its preparation method, specifically to a catalyst for the catalytic hydrogenation of squalene under solvent-free conditions and its preparation method, belonging to the field of fine chemical synthesis technology. Background Technology

[0002] Squalane is a high-performance saturated hydrocarbon with excellent chemical stability, skin affinity, and permeability, making it widely used in high-end cosmetics, pharmaceuticals, and precision lubricants. Industrially, squalane is primarily derived from squalene (C463- ... 30 H 50 It is prepared by catalytic hydrogenation of a highly unsaturated triterpenoid.

[0003] Squalene molecules contain six carbon-carbon double bonds, and their complete hydrogenation yields squalane (C6H2O). 30 H 62 This is a deep hydrogenation process. The challenges it faces are: 1) requiring a highly active catalyst to achieve complete hydrogenation and avoid residual hydrogenation products; 2) requiring extremely high selectivity to prevent side reactions such as cracking and isomerization caused by over-hydrogenation under harsh conditions, which would reduce product purity, color and produce off-odors; 3) requiring the catalyst to have good stability to withstand possible trace impurities (such as sulfur-containing and nitrogen-containing compounds).

[0004] Currently, palladium-on-carbon catalysts and Raney nickel or supported nickel catalysts are commonly used in industry. However, these catalysts require harsh reaction conditions, have relatively poor selectivity, are prone to generating byproducts, and the issue of residual nickel in post-processing is a major concern. While noble metal palladium (Pd) catalysts exhibit excellent hydrogenation activity, on traditional supports (such as activated carbon), they are often prone to isomerization or excessive adsorption of large molecules with multiple double bonds, such as squalene, leading to catalyst deactivation. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a highly efficient and stable cerium oxide-supported palladium catalyst for the catalytic hydrogenation of squalene under solvent-free conditions. This catalyst not only has a low palladium loading and requires a small amount, but also achieves 100% conversion and 100% yield in the solvent-free catalytic hydrogenation of squalene. This catalyst has advantages such as high activity, high yield, and high selectivity, effectively reducing the cost of the squalene hydrogenation reaction.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A cerium oxide-supported highly dispersed palladium catalyst for the hydrogenation reaction of squalene under solvent-free conditions and its preparation are disclosed. The catalyst uses cerium oxide as a support and palladium as the active center. The palladium loading is 0.1wt%-5wt% of the total catalyst, and the palladium to substrate ratio is 0.01-0.5wt‰.

[0008] A method for preparing the cerium oxide-supported palladium catalyst as described above specifically includes the following steps:

[0009] Preparation of cerium oxide support:

[0010] The support was prepared by hydrothermal method. The cerium precursor was added to the solvent, and the additive was added to the above mixed solution. After stirring evenly, the additive and reducing agent were added to the solution respectively. After stirring evenly, the solution was placed in a reaction vessel and hydrothermally heated at 100℃-300℃ for 5h-24h. After cooling to room temperature, the resulting solution was centrifuged and washed, and dried at 50℃-80℃ for 5h-48h. The resulting solid was ground and calcined at 100℃-500℃ for 1h-5h to obtain the cerium oxide support.

[0011] The cerium precursor mentioned in the above steps is one or a mixture of cerium oxalate, cerium chloride, cerium nitrate, cerium acetate, cerium sulfate, cerium ammonium nitrate, and cerium carbonate. The solvent is one or a mixture of water, methanol, ethanol, ethylene glycol, glycerol, isopropanol, formic acid, propionic acid, ethylenediamine, aniline, and N,N-dimethylformamide. The additive is one or a mixture of polyethylene glycol, sodium polyacrylate, polyvinylpyrrolidone, polyvinyl alcohol, dodecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and sodium dodecylbenzene sulfate. The reducing agent is one or a mixture of sodium hypophosphite, sodium sulfite, hydrazine hydrate, ethylene glycol, ascorbic acid, and glucose.

[0012] Preparation of cerium oxide-supported palladium catalysts:

[0013] Palladium was loaded using a deposition-precipitation method. The above-mentioned support was placed in deionized water, and a palladium precursor was added. The mixture was stirred at 20℃-80℃ for 1h-12h, and a precipitant was added to adjust the solution to alkaline. The mixture was stirred continuously for 5h-24h, filtered and washed, dried at 50℃-80℃ for 8h-24h, calcined at 100℃-500℃ for 1h-5h, and reduced at 100℃-500℃ for 1h-5h under a hydrogen atmosphere to obtain the catalyst.

[0014] The palladium precursor mentioned in the above steps is one or a mixture of palladium chloride, palladium nitrate, palladium acetate, and palladium acetylacetonate. The precipitant is one or a mixture of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, ammonium carbonate, ammonium bicarbonate, ammonia, urea, and tetramethylammonium hydroxide.

[0015] Application of the cerium oxide-supported palladium catalyst described above in the solvent-free catalytic hydrogenation of squalene:

[0016] Squalene and a quantitative amount of catalyst were added to the liner of the reactor. The ratio of palladium to substrate was 0.01-0.5 wt‰. The mixture was stirred and mixed evenly under solvent-free conditions. The liner was then transferred to the reactor. Nitrogen was purged three times to remove air from the reactor. Hydrogen was purged three times. The final hydrogen pressure in the reactor was 0.1-1 MPa. The reactor was heated to 20℃-80℃ and reacted for 1-20 hours. After the reaction was completed, a quantitative amount of hexadecane internal standard was added. The reaction conversion and yield were obtained by gas chromatography.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention provides a highly efficient and stable cerium oxide-supported palladium catalyst and its application in the solvent-free catalytic hydrogenation of squalene. The catalyst is prepared by optimizing processes and parameters to produce nano-cerium oxide, and a highly dispersed supported palladium catalyst is prepared via a deposition-precipitation method. The cerium oxide and highly dispersed palladium synergistically catalyze hydrogenation through morphology effects, significantly improving hydrogenation activity and exhibiting high selectivity. Compared to traditional palladium-on-carbon catalysts and Raney nickel or supported nickel catalysts, this invention reduces energy consumption, simplifies separation and purification processes, utilizes a solvent-free system, lowers reaction costs, simplifies catalyst preparation, uses readily available raw materials, and allows for large-scale production. Attached Figure Description

[0019] Figure 1 The table shows the catalytic activity of each embodiment. Detailed Implementation

[0020] The present invention will be described in detail below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0021] Example 1: Preparation and Activity Testing of Cerium Oxide-Supported Palladium Catalyst

[0022] Preparation of cerium oxide support: 5.2080g Ce(NO3)3·6H2O and 60mL deionized water were mixed evenly, and 1.5g polyvinylpyrrolidone (PVP) was added. After stirring for 30min to form a transparent solution, 12mL hydrazine hydrate (85%) was added and stirred for 30min. The resulting solution was placed in a 250mL polytetrafluoroethylene liner and then placed in a stainless steel reactor. The reactor was hydrothermally heated at 180℃ for 12 hours. After cooling, the precipitate was collected and washed three times with deionized water and anhydrous ethanol, respectively. The precipitate was then dried in an oven at 80℃ for 12h. After drying, the powder was thoroughly ground and calcined in a muffle furnace at 400℃ for 4h with a heating rate of 2℃ / min to obtain CeO2 support, denoted as CeO2.

[0023] Preparation of palladium catalyst supported on cerium oxide: 0.5 g of CeO2 support was weighed and dispersed in 100 mL of water. 0.635 mL of palladium nitrate aqueous solution (Pd content 7.9 mg / mL) was added. After stirring at room temperature for 8 h, the mixture was stirred at 60 °C for 1 h. The pH was adjusted to 10-11 with 10% Na2CO3 solution, and stirring was continued at 60 °C for 12 h. After cooling, the precipitate was collected and washed three times with deionized water. The precipitate was dried in an oven at 80 °C for 12 h. After drying, the powder was thoroughly ground and calcined in a muffle furnace at 350 °C for 2 h with a heating rate of 2 °C / min. Then, the powder was reduced in a tube furnace at 200 °C for 1 h with a heating rate of 3 °C / min to obtain the catalyst, denoted as 1% Pd / CeO2.

[0024] Activity testing of cerium oxide-supported palladium catalyst: 3 mL of squalene (2.57 g) and 0.0206 g of catalyst (Pd to substrate ratio 0.08 wt‰) were added to the liner of the reactor. Under solvent-free conditions, the mixture was stirred until homogeneous. The liner was then transferred to the reactor. Nitrogen was purged three times to remove air from the reactor, followed by hydrogen purging three times, resulting in a final hydrogen pressure of 0.3 MPa. The reactor was heated to 80 °C and reacted for 10 h. After the reaction, a quantitative amount of hexadecane internal standard was added. The conversion and yield were obtained by gas chromatography. The yield of the 1% Pd / CeO2 catalyst in the above reaction was calculated to be 100%.

[0025] Example 2: Preparation and Activity Testing of Cerium Oxide-Supported Palladium Catalyst

[0026] Preparation of cerium oxide support: Unlike Example 1, this example uses cerium acetate as the cerium precursor, and the rest of the preparation process is the same as in Example 1.

[0027] The preparation process of the supported palladium catalyst is the same as in Example 1. It is denoted as 1%Pd / CeO2-2.

[0028] The squalene catalytic hydrogenation reaction was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / CeO₂⁻⁂ catalyst in the above reaction was 85%.

[0029] Example 3: Preparation and Activity Testing of Cerium Oxide-Supported Palladium Catalyst

[0030] Preparation of cerium oxide support: Unlike Example 1, this example uses ethanol as a solvent, and the rest of the preparation process is the same as in Example 1.

[0031] The catalyst preparation process is the same as in Example 1. It is denoted as 1%Pd / CeO2-3.

[0032] The catalytic hydrogenation reaction of squalene was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / CeO₂⁻⁻ catalyst in the above reaction was 76%.

[0033] Example 4: Preparation and Activity Testing of Cerium Oxide-Supported Palladium Catalyst

[0034] Preparation of cerium oxide carrier: Unlike Example 1, this example uses polyethylene glycol as an additive, and the rest of the preparation process is the same as in Example 1.

[0035] The catalyst preparation process is the same as in Example 1. It is denoted as 1%Pd / CeO2-4.

[0036] The catalytic hydrogenation reaction of squalene was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / CeO₂⁻⁴ catalyst in the above reaction was 73%.

[0037] Example 5: Preparation and Activity Testing of Cerium Oxide-Supported Palladium Catalyst

[0038] Preparation of cerium oxide support: Unlike Example 1, this example uses sodium hypophosphite as a reducing agent, and the rest of the preparation process is the same as in Example 1.

[0039] The catalyst preparation process is the same as in Example 1. It is denoted as 1%Pd / CeO2-5.

[0040] The catalytic hydrogenation reaction of squalene was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / CeO₂-₅ catalyst in the above reaction was 65%.

[0041] Example 6: Preparation and Activity Testing of Cerium Oxide-Supported Palladium Catalyst Using Palladium Acetate as Palladium Precursor

[0042] The carrier preparation process is the same as in Example 1.

[0043] Catalyst preparation: Unlike Example 1, palladium acetate was used as the palladium precursor in this example. The rest of the preparation process was the same as in Example 1, denoted as 1%Pd / CeO2-6.

[0044] The catalytic hydrogenation reaction of squalene was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / CeO₂-6 catalyst in the above reaction was 89%.

[0045] Example 7: Preparation and Activity Testing of Cerium Oxide-Supported Palladium Catalyst Using Sodium Hydroxide as a Precipitator

[0046] The carrier preparation process is the same as in Example 1.

[0047] Catalyst preparation: Unlike Example 1, the precipitant used in the cerium oxide-supported palladium process in this example is sodium hydroxide, and the rest of the preparation process is the same as in Example 1, referred to as 1%Pd / CeO2-7.

[0048] The catalytic hydrogenation reaction of squalene was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / CeO₂-7 catalyst in the above reaction was 72%.

[0049] Example 8: Preparation and Activity Testing of Cerium Oxide-Supported Palladium Catalyst Using Potassium Hydroxide as a Precipitator

[0050] The carrier preparation process is the same as in Example 1.

[0051] Catalyst preparation: Unlike Example 1, the precipitant used in the cerium oxide-supported palladium process in this example is potassium hydroxide, and the rest of the preparation process is the same as in Example 1, referred to as 1%Pd / CeO2-8.

[0052] The catalytic hydrogenation reaction of squalene was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / CeO₂-8 catalyst in the above reaction was 84%.

[0053] Example 9: Preparation and Activity Testing of Cerium Oxide-Supported 2wt% Palladium Catalyst

[0054] The carrier preparation process is the same as in Example 1.

[0055] Unlike Example 1, the amount of palladium supported on cerium oxide in this example is 2%, and the rest of the preparation process is the same as in Example 1, referred to as 2%Pd / CeO2.

[0056] The squalene catalytic hydrogenation reaction was tested in the same manner as in Example 1. Calculations showed that the yield of the 2% Pd / CeO2 catalyst in the above reaction was 100%.

[0057] Example 10 Preparation and Activity Testing of Cerium Oxide-Supported 0.5wt% Palladium Catalyst

[0058] The carrier preparation process is the same as in Example 1.

[0059] Unlike Example 1, the amount of palladium supported on cerium oxide in this example is 0.5%, and the rest of the preparation process is the same as in Example 1, referred to as 0.5%Pd / CeO2.

[0060] The squalene catalytic hydrogenation reaction was tested in the same manner as in Example 1. The calculated yield of the 0.5% Pd / CeO2 catalyst in the above reaction was 63%.

[0061] Comparative Example 1: Preparation and Activity Testing of Palladium Catalyst Supported by Cerium Oxide Impregnation Method

[0062] The carrier preparation process is the same as in Example 1.

[0063] Unlike Example 1, this example uses an impregnation method to support palladium. The specific preparation process is as follows: 0.5g of CeO2 support is weighed into a beaker, and 0.635mL of palladium nitrate aqueous solution (Pd content is 7.9mg / mL) is added. The mixture is stirred at room temperature for 30min and mixed evenly. It is then impregnated overnight, and the water is slowly heated to 60℃ in a water bath to evaporate the water. Then it is placed in an 80℃ oven to dry overnight. After drying, it is thoroughly ground and the powder is calcined in a muffle furnace at 300℃ for 4h with a heating rate of 2℃ / min. Then it is reduced in a tube furnace at 200℃ for 2h with a heating rate of 3℃ / min to obtain the catalyst, denoted as 1%Pd / CeO2-9.

[0064] The catalytic hydrogenation reaction of squalene was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / CeO2-9 catalyst in the above reaction was 37%.

[0065] Comparative Example 2: Activity Test of 1% Pd / C Catalyst

[0066] Unlike Example 1, the carrier used in this example is a carbon carrier in the carrier preparation process.

[0067] The catalyst preparation process is the same as in Example 1, denoted as 1%Pd / C.

[0068] The catalytic hydrogenation reaction of squalene was tested in the same manner as in Example 1. The calculated yield of the 1% Pd / C catalyst in the above reaction was 45%.

[0069] The above description is a further detailed explanation of the present invention in conjunction with specific embodiments. It should not be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, any simple modifications and substitutions made without departing from the concept of the present invention should be considered to fall within the protection scope of the present invention.

Claims

1. A catalyst for the solvent-free hydrogenation of squalene, characterized in that: The solvent-free squalene hydrogenation reaction is as follows: raw material squalene and a quantitative catalyst are added to the liner of the reactor. The ratio of palladium to substrate is 0.01-0.5 wt‰. Under solvent-free conditions, the mixture is stirred and mixed evenly. The liner of the reactor is transferred to the reactor. Nitrogen gas is purged three times to remove air from the reactor. Hydrogen gas is purged three times. The final hydrogen pressure in the reactor is 0.1-1 MPa. The reactor is heated to 20℃-80℃ and reacted for 1-20 hours. After the reaction is completed, a quantitative hexadecane internal standard is added. The reaction conversion rate and yield are obtained by gas chromatography. The catalyst uses cerium oxide as a support and palladium as the active center, with the palladium loading being 0.1 wt% to 5 wt% of the total catalyst.

2. The catalyst for the solvent-free hydrogenation of squalene according to claim 1, wherein the preparation method of the support is as follows: The support was prepared by hydrothermal method. The cerium precursor was added to the solvent, and the additive was added to the above mixed solution. After stirring evenly, the reducing agent was added to the solution and stirred evenly. The solution was then placed in a reaction vessel and hydrothermally heated at 100℃-300℃ for 5h-24h. After cooling to room temperature, the resulting solution was centrifuged and washed, and dried at 50℃-80℃ for 5h-48h. The resulting solid was ground and calcined at 100℃-500℃ for 1h-5h to obtain the cerium oxide support.

3. The catalyst for the solvent-free hydrogenation of squalene according to claim 1, characterized in that: The cerium precursor is one or a mixture of cerium oxalate, cerium chloride, cerium nitrate, cerium acetate, cerium sulfate, cerium ammonium nitrate, and cerium carbonate. The solvent is one or a mixture of water, methanol, ethanol, ethylene glycol, glycerol, isopropanol, formic acid, propionic acid, ethylenediamine, aniline, and N,N-dimethylformamide; The additive is one or more of the following: polyethylene glycol, sodium polyacrylate, polyvinylpyrrolidone, polyvinyl alcohol, dodecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and sodium dodecylbenzene sulfate. The reducing agent is one or a mixture of sodium hypophosphite, sodium sulfite, hydrazine hydrate, ethylene glycol, ascorbic acid, and glucose.

4. A method for preparing a catalyst for the catalytic hydrogenation of squalene under solvent-free conditions, characterized in that: Palladium was loaded using a deposition-precipitation method. The above-mentioned support was placed in deionized water, and a palladium precursor was added. The mixture was stirred at 20℃-80℃ for 1h-12h, and a precipitant was added to adjust the solution to alkaline. The mixture was stirred continuously for 5h-24h, filtered and washed, dried at 50℃-80℃ for 8h-24h, calcined at 100℃-500℃ for 1h-5h, and reduced at 100℃-500℃ for 1h-5h under a hydrogen atmosphere to obtain the catalyst.

5. The method for preparing a catalyst for the solvent-free hydrogenation reaction of squalene according to claim 4, characterized in that: The palladium precursor is one or a mixture of palladium chloride, palladium nitrate, palladium acetate, and palladium acetylacetonate. The precipitant is one or more of the following: sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, ammonium carbonate, ammonium bicarbonate, ammonia, urea, and tetramethylammonium hydroxide.

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