Cinnamaldehyde selective hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention relates to the field of catalysts, and discloses a cinnamyl aldehyde selective hydrogenation catalyst and a preparation method and application thereof. The catalyst comprises a carrier and an active component loaded on the carrier, the carrier is macroporous alumina, the specific surface area of the carrier is 95-195 cm < 2 > / g, the average mesopore diameter of the carrier is 20-90 nm, the water absorption rate of the carrier is 205-300%, and the active component is selected from at least one of Ru, Rh, Pt and Pd. The catalyst provided by the invention has good catalytic activity and cinnamyl aldehyde selective hydrogenation performance, by adopting the preparation method of the catalyst provided by the invention, the catalyst with good active component dispersity can be obtained, and the use cost of the catalyst can be reduced while the service life of the noble metal catalyst can be greatly prolonged. In addition, the preparation method of the catalyst is simple and controllable.

Description

Technical Field

[0001] This invention relates to the field of catalysts, and more specifically, to a selective hydrogenation catalyst for cinnamaldehyde, its preparation method, and its application. Background Technology

[0002] Phenylacetaldehyde and cinnamyl alcohol are intermediate products in the hydrogenation process of cinnamaldehyde. Since cinnamaldehyde is an α,β-unsaturated aldehyde, it can selectively generate phenylpropanaldehyde or cinnamyl alcohol under the action of different catalysts. Since both contain C=C double bonds or C=O double bonds, they can continue to react with hydrogen to eventually generate phenylpropanol or 3-cyclohexyl-1-propanol.

[0003] Phenylacetaldehyde is a chemical substance used as a flavoring agent in the flavorings of almonds, berries, grapes, cherries, peaches, plums, cinnamon, and other fruits. It is also an important pharmaceutical intermediate. Due to its C=O double bond, it exhibits high reactivity during reactions and is widely used in the pharmaceutical, cosmetic, food processing, and chemical industries. Particularly in the pharmaceutical industry, phenylpropanal has attracted significant attention due to its proven use as an intermediate in the synthesis of AIDS drugs.

[0004] The selective hydrogenation of cinnamaldehyde is highly economical and aligns with green manufacturing principles. Cinnamaldehyde is an α,β-unsaturated aldehyde containing C=C and C=O bonds. The bond energy of the C=C bond is 615 kJ / mol, and that of the C=O bond is 715 kJ / mol. Comparative chemistry data shows that the C=C double bond is more readily hydrogenated than the C=O double bond. A single hydrogenation reaction with hydrogen gas selectively yields phenylpropanaldehyde. However, if the reaction conditions are not precisely controlled, resulting in an excessively long residence time of phenylpropanaldehyde, it will undergo further hydrogenation to form phenylpropanol. Therefore, phenylpropanaldehyde, as an intermediate product in this reaction, requires a catalyst with extremely high selectivity.

[0005] CN108435167A discloses a catalyst for preparing phenylpropionaldehyde. This catalyst uses noble metal active components Pd and Ag, supported on a porous material MCM-41, SiO2, SBA-15, or activated carbon. However, this catalyst uses a large number of noble metal components, which leads to excessively high overall costs. Furthermore, the preparation process requires the addition of 10% by weight of NaOH solution to adjust the pH, generating a large amount of alkaline wastewater, which increases the difficulty of subsequent industrial-scale catalyst production.

[0006] Noble metal catalysts are commonly used in various industrial catalytic reactions, especially in the petroleum, chemical, and pharmaceutical industries. However, precious metals themselves are expensive, so many researchers are dedicated to studying how to reduce the cost of precious metal catalysts. Therefore, developing a low-cost, stable, and long-life precious metal catalyst is particularly necessary. Summary of the Invention

[0007] The purpose of this invention is to overcome the aforementioned problems in the prior art and to provide a selective hydrogenation catalyst for cinnamaldehyde, its preparation method, and its application.

[0008] To achieve the above objectives, the present invention provides a selective hydrogenation catalyst for cinnamaldehyde, the catalyst comprising a support and an active component supported on the support, wherein the support is macroporous alumina, and the specific surface area of ​​the support is 95-195 cm². 2 / g, the average pore size of the carrier is 20-90nm, the water absorption rate of the carrier is 205-300%, and the active component is selected from at least one of Ru, Rh, Pt and Pd.

[0009] A second aspect of this invention provides a method for preparing a selective hydrogenation catalyst for cinnamaldehyde, the method comprising:

[0010] 1) Boehmite was prepared using the sulfuric acid process;

[0011] 2) The carrier is obtained by crystallizing boehmite, first drying, and first calcining at 1000-1150℃;

[0012] 3) The support is impregnated in the precursor solution of the active component, and the selective hydrogenation catalyst is obtained by second drying and second calcination;

[0013] The sulfur content in the boehmite is 1-3.4% by weight, and the active component is at least one of Ru, Rh, Pt and Pd.

[0014] A third aspect of the present invention provides a selective hydrogenation catalyst for cinnamaldehyde prepared by the method described above.

[0015] A fourth aspect of the present invention provides a method for selectively hydrogenating cinnamaldehyde to prepare phenylpropionaldehyde, the method comprising selectively hydrogenating cinnamaldehyde in the presence of the catalyst and solvent as described above.

[0016] The fifth aspect of this invention provides the application of the catalyst as described above in the selective hydrogenation of cinnamaldehyde to prepare phenylpropionaldehyde.

[0017] Through the above technical solutions, the catalyst provided by this invention exhibits excellent catalytic activity and selective hydrogenation performance of cinnamaldehyde. The preparation method of the catalyst described in this invention can yield a catalyst with good dispersion of active components, significantly improving the service life of precious metal catalysts while reducing their usage costs. Furthermore, the preparation method of the catalyst described in this invention is simple and controllable. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] This invention provides a selective hydrogenation catalyst for cinnamaldehyde, the catalyst comprising a support and an active component supported on the support, wherein the support is macroporous alumina with a specific surface area of ​​95-195 cm². 2 / g, the average pore size of the carrier is 20-90nm, the water absorption rate of the carrier is 205-300%, and the active component is selected from at least one of Ru, Rh, Pt and Pd.

[0020] According to the present invention, preferably, based on the total weight of the catalyst, the content of the support is 99.5-99.9% by weight and the content of the active component is 0.1-0.5% by weight; more preferably, based on the total weight of the catalyst, the content of the support is 99.6-99.8% by weight and the content of the active component is 0.2-0.4% by weight.

[0021] According to the present invention, preferably, the active component is selected from at least one of Ru, Rh, and Pd. Using the active component described in this invention can further enhance the catalytic activity and selectivity of the catalyst.

[0022] According to the present invention, preferably, the average pore size of the mesopores of the carrier is 20-32 nm.

[0023] According to the present invention, preferably, the specific surface area of ​​the carrier is 95-145 cm². 2 / g.

[0024] According to the present invention, preferably, the pore volume of the carrier is 0.5-1.4 cm. 3 / g.

[0025] According to the present invention, preferably, the water absorption rate of the carrier is 210-250%.

[0026] According to the present invention, preferably, the sulfur content of the alumina support is 0.01-0.19% by weight.

[0027] According to the present invention, preferably, the dispersity of the active component is 5-9%.

[0028] In this invention, when the average pore size, specific surface area, pore volume and water absorption rate of the carrier meet the above-mentioned ranges, it is beneficial to further increase the loading of noble metals and further enhance the catalytic activity of the catalyst.

[0029] A second aspect of this invention provides a method for preparing a selective hydrogenation catalyst for cinnamaldehyde, the method comprising:

[0030] 1) Boehmite was prepared using the sulfuric acid process;

[0031] 2) The carrier is obtained by crystallizing boehmite, first drying, and first calcining at 1000-1150℃;

[0032] 3) The support is impregnated in a precursor solution of the active component, and the selective hydrogenation catalyst is obtained by second drying and second calcination; wherein the sulfur content in the boehmite is 1-3.4% by weight, and the active component is at least one of Ru, Rh, Pt and Pd.

[0033] According to the present invention, preferably, the method for preparing boehmite by the sulfuric acid method includes: mixing an alkaline sodium aluminate solution with an aluminum sulfate solution to make the pH of the system 8-10.

[0034] According to the present invention, preferably, the sodium aluminate content in the alkaline sodium aluminate is 4-21% by weight, OH - The content is 2-9% by weight, and more preferably, the content of sodium aluminate in the alkaline sodium aluminate is 6-12% by weight, OH - The content is 3-6% by weight.

[0035] In this invention, the alkaline sodium aluminate aqueous solution can be controlled by an alkali metal hydroxide (such as sodium hydroxide). According to one embodiment of the invention, the alkaline sodium aluminate solution is prepared by mixing sodium hydroxide and sodium aluminate with a solvent. The amount of solvent is sufficient to completely dissolve the sodium aluminate. The solvent is not specifically required and can be water or a lower alcohol, preferably at least one of deionized water and ethanol.

[0036] According to the present invention, preferably, the concentration of the aluminum sulfate solution is 0.3-0.9 mol / L, more preferably 0.4-0.7 mol / L.

[0037] In this invention, when the concentration of the aluminum sulfate solution meets the above-mentioned range, the prepared boehmite can have a larger average mesopore size, thereby giving the catalyst prepared subsequently greater catalytic activity.

[0038] In this invention, the specific conditions for reacting the alkaline sodium aluminate aqueous solution and the aluminum sulfate aqueous solution are not limited and can be conventional methods used in the art. Preferably, the reaction method involves adding the alkaline sodium aluminate aqueous solution dropwise to the aluminum sulfate aqueous solution at room temperature.

[0039] According to the present invention, preferably, the carrier is macroporous alumina with a mixed θ and δ phase structure.

[0040] According to the present invention, preferably, the weight ratio of the active component to the support, based on metal elements, is 1:199-999, more preferably 1:249-499. When the weight ratio of the active component to the support is within the above range, the catalyst selectivity can be further improved while reducing the catalyst production cost.

[0041] In this invention, when the pH of the mixed system is within the above-mentioned range, it can accelerate the precipitation rate in the solution and enable the prepared boehmite to have a larger specific surface area, which is more conducive to ensuring that the subsequent preparation of an alumina carrier with a larger average mesoporous pore size and higher water absorption rate is obtained.

[0042] According to the present invention, preferably, the active component in the cinnamaldehyde selective hydrogenation catalyst is at least one of Ru, Rh and Pd.

[0043] In this invention, the precursor of the active component is selected from its corresponding soluble salt. The soluble salt can be any of the commonly chosen options. Preferably, the precursor of the active component is selected from at least one of ruthenium nitrate, rhodium nitrate, platinum nitrate, palladium nitrate, ruthenium carbonate, rhodium carbonate, platinum carbonate, and palladium carbonate. More preferably, the precursor of the active component is selected from at least one of ruthenium nitrate, rhodium nitrate, palladium nitrate, ruthenium carbonate, rhodium carbonate, and palladium carbonate.

[0044] In this invention, the soluble salt refers to salt that is soluble in water or lower alcohols. Preferably, the soluble salt refers to salt that is soluble in ethanol or deionized water.

[0045] According to the present invention, preferably, the sulfur content in the boehmite is 1.3-1.9% by weight. When the sulfur content of the boehmite in the present invention is within the above range, the resulting alumina has a larger average mesopore size and a higher water absorption rate.

[0046] According to the present invention, preferably, the crystallization conditions include a temperature of 60-110°C and a time of 5-24 hours. More preferably, the crystallization conditions include a temperature of 70-90°C and a time of 8-13 hours.

[0047] According to the present invention, preferably, the conditions for the first drying include: a temperature of 80-160°C and a time of 1-4 hours. More preferably, the conditions for the first drying include: a temperature of 110-130°C and a time of 1.5-3 hours.

[0048] According to the present invention, preferably, the conditions for the first calcination include: a temperature of 1000-1150°C and a time of 4-10 hours. More preferably, the conditions for the first calcination include: a temperature of 1000-1100°C and a time of 5-8 hours.

[0049] In this invention, the roasting atmosphere is not particularly limited and can be any gas commonly used in the art. Preferably, the gas is at least one of nitrogen, oxygen, argon, or air, with air being the most preferred.

[0050] In this invention, the preparation conditions of the support are within the above-mentioned range, which can further improve the characteristics of the support and thus improve the overall performance of the catalyst.

[0051] In this invention, the method may further include a forming step to obtain alumina of a specific shape. There is no particular limitation on the shape of the prepared alumina carrier; any shape conventionally prepared in the art can be used. Preferably, the carrier shape is at least one of cylindrical, spherical, or trilobal, with a cylindrical shape being the most preferred.

[0052] According to the present invention, preferably, the conditions for the second drying include: a temperature of 60-120°C and a time of 3-12 hours. More preferably, the conditions for the second drying include: a temperature of 90-110°C and a time of 4-9 hours.

[0053] According to the present invention, preferably, the conditions for the second calcination are: a temperature of 300-400°C and a time of 4-7 hours. More preferably, the conditions for the second calcination are: a temperature of 320-380°C and a time of 5-6 hours.

[0054] In this invention, the roasting atmosphere is not particularly limited and can be any gas commonly used in the art. Preferably, the gas is at least one of nitrogen, oxygen, argon, or air, with air being the most preferred.

[0055] A third aspect of the present invention provides a selective hydrogenation catalyst for cinnamaldehyde prepared by the method described above.

[0056] A fourth aspect of the present invention provides a method for selectively hydrogenating cinnamaldehyde to prepare phenylpropionaldehyde, the method comprising selectively hydrogenating cinnamaldehyde in the presence of the catalyst and solvent as described above.

[0057] In this invention, the reduction conditions are conventionally chosen in the art. Preferably, the reduction conditions for the catalyst include: an H2 atmosphere, a temperature of 400-500℃, and a time of 4-6 hours. The H2 flow rate in this invention is 150-250 mL / min, and the catalyst is reduced by increasing the temperature to 400-500℃ at a rate of 3-8℃ / min.

[0058] According to the present invention, preferably, the passivation conditions for the catalyst are: natural conditions, passivation for 0.5-2 hours. In this invention, passivation refers to cooling the reduced catalyst and then introducing a small amount of air under natural conditions to obtain the finished catalyst. The purpose of passivation is to form a thin oxide film on the surface of the reduced catalyst. This oxide film prevents further oxidation and deterioration of the catalyst upon contact with air, making the catalyst easy to store and reuse.

[0059] According to the present invention, preferably, the solvent may be at least one of methanol, ethanol and propanol.

[0060] According to the present invention, preferably, the amount of solvent used is 15-31 mL per gram of the above catalyst, and the amount of cinnamaldehyde used is 4-10 mL.

[0061] According to the present invention, preferably, the selective hydrogenation reaction conditions include: a reaction temperature of 70-90°C, a reaction hydrogen pressure of 1-4 MPa, and a reaction time of 1-5 h.

[0062] The fifth aspect of the present invention provides the application of the catalyst described above in the selective hydrogenation of cinnamaldehyde to prepare phenylpropionaldehyde.

[0063] The present invention will be described in detail below through examples. In the following examples and comparative examples, the elemental content detection method is X-ray fluorescence spectrometry (XRF).

[0064] Preparation Example 1

[0065] (1) Weigh 22.56g NaOH and 17.5g sodium aluminate and dissolve them in 250ml deionized water for later use.

[0066] (2) Weigh 88.4g of aluminum sulfate into 500ml of deionized water, add the sodium aluminate solution prepared in step 1) dropwise into the aluminum sulfate solution with a concentration of 0.5mol / L until the pH is 9, stir at room temperature for 60min to obtain boehmite precursor.

[0067] (3) Continue crystallization at 80℃ for 12 hours, and then dry at 120℃ for 2 hours to obtain boehmite with a large specific surface area (specific surface area of ​​456 cm²). 2 / g).

[0068] (4) Use a tablet press to press boehmite into cylindrical particles of 5mm*3mm. Then, calcine them at 1100℃ for 6 hours in air to obtain macroporous alumina carrier (sulfur content of 0.08wt%).

[0069] Preparation Example 2

[0070] (1)-(3) are the same as in Example 1.

[0071] (4) Use a tablet press to press boehmite into cylindrical particles of 5mm*3mm. Then, calcine them at 1000℃ for 6 hours in air to obtain macroporous alumina carrier (sulfur content of 0.15wt%).

[0072] Preparation Example 3

[0073] (1)-(3) are the same as in Experiment 1.

[0074] (4) Use a tablet press to press boehmite into cylindrical particles of 5mm*3mm. Then, calcine them at 1050℃ for 6 hours in air to obtain macroporous alumina carrier (sulfur content of 0.09wt%).

[0075] Preparation Example 4

[0076] (1) Weigh 22.56g NaOH and 17.5g sodium aluminate and dissolve them in 250ml deionized water for later use.

[0077] (2) Weigh 88.4g of aluminum sulfate into 500ml of deionized water, add the sodium aluminate solution prepared in step 1) dropwise into the aluminum sulfate solution with a concentration of 0.5mol / L until the pH is 9, stir at room temperature for 60min to obtain boehmite precursor.

[0078] (3) Continue crystallization at 80℃ for 11 hours and dry at 120℃ for 2 hours to obtain boehmite with a large specific surface area.

[0079] (4) Use a tablet press to press boehmite into cylindrical particles of 5mm*3mm. Then calcine them at 1050℃ for 6 hours in air to obtain macroporous alumina carrier (sulfur content of 0.3% by weight).

[0080] Example 1

[0081] 0.3 g of palladium nitrate aqueous solution (10 wt%, based on Pd) was diluted with 10 mL of deionized water and loaded onto a support (the alumina support obtained in Preparation Example 1) using an equal-volume impregnation method. The impregnated product was placed in an oven and dried at 100 °C for 5 hours. The dried product was then placed in a muffle furnace and calcined for a second time at 350 °C for 5 hours in an air atmosphere to obtain catalyst C1.

[0082] Example 2

[0083] 0.3 g of palladium nitrate aqueous solution (10 wt%, based on Pd) was diluted with 10 mL of deionized water and loaded onto a support (the alumina support obtained in Preparation Example 2) using an equal-volume impregnation method. The impregnated product was placed in an oven and dried at 100 °C for 5 hours. The dried product was then placed in a muffle furnace and calcined for a second time at 350 °C for 5 hours in an air atmosphere to obtain catalyst C2.

[0084] Example 3

[0085] 0.3 g of palladium nitrate aqueous solution (10 wt%, based on Pd) was diluted with 10 mL of deionized water and loaded onto a support (the alumina support obtained in Preparation Example 3) using an equal-volume impregnation method. The impregnated product was placed in an oven and dried at 100 °C for 8 hours. The dried product was then placed in a muffle furnace and calcined for a second time at 350 °C for 5 hours in an air atmosphere to obtain catalyst C3.

[0086] Example 4

[0087] The catalyst was prepared according to the method of Example 3, except that the alumina support was obtained from Preparation Example 4, and finally catalyst C4 was obtained.

[0088] Example 5

[0089] The catalyst was prepared according to the method of Example 3, except that the drying temperature was 120°C and the time was 3 hours; the second calcination temperature was 400°C and the time was 7 hours, to obtain catalyst C5.

[0090] Example 6

[0091] The catalyst was prepared according to the method of Example 3, except that the palladium active component was replaced with ruthenium, resulting in catalyst C6.

[0092] Example 7

[0093] The catalyst was prepared according to the method of Example 3, except that the amount of active component was adjusted so that the content of active component in the catalyst was 1% by weight, resulting in catalyst C7.

[0094] Comparative Example 1

[0095] 37.17 g of nickel nitrate was dissolved in deionized water at 60 °C and then loaded onto alumina treated at 900 °C using an equal-volume impregnation method. (The alumina carrier particles were purchased from Shandong Taiguang Company and had a specific surface area of ​​104 cm³.) 2 / g, pore volume 0.41cm 3 / g, with a carrier water absorption rate of 95%, the impregnated product was placed in an oven at 100℃ and dried for 12h. The dried product was then placed in a muffle furnace and calcined at 350℃ for 5h in air atmosphere to finally obtain catalyst D1.

[0096] Comparative Example 2

[0097] 37.04 g of cobalt nitrate was dissolved in deionized water at 60 °C and then loaded onto alumina treated at 900 °C using an equal-volume impregnation method. (This alumina was a self-made carrier from the Beijing Research Institute of Chemical Industry, with a specific surface area of ​​121.2 cm².) 2 / g, with an average mesopore diameter of 16nm and a support water absorption rate of 103%), the impregnated product was placed in an oven at 100℃ and dried for 12h. The dried product was then placed in a muffle furnace and calcined at 350℃ for 6h in an air atmosphere to finally obtain catalyst D2.

[0098] Comparative Example 3

[0099] The catalyst was prepared according to Example 3, except that boehmite was pressed into 5mm*3mm cylindrical particles using a tablet press. These particles were then calcined for the first time at 600°C for 6 hours in air to obtain a macroporous alumina support (sulfur content 2.1wt%), and finally, catalyst D3 was obtained.

[0100] Comparative Example 4

[0101] The catalyst was prepared according to Example 3, except that boehmite was pressed into 5mm*3mm cylindrical particles using a tablet press. These particles were then calcined for the first time at 1200°C for 6 hours in air to obtain a macroporous alumina support (sulfur not detected), and finally, catalyst D4 was obtained.

[0102] Comparative Example 5

[0103] The catalyst was prepared according to Example 3, except that the crystallized product was washed five times with deionized water and then dried at 120°C for 2 hours to obtain boehmite with a large specific surface area. BET characterization of the support showed that its mesopore size distribution was 15-40 nm, its water absorption rate was 90%, and the sulfur content of the support was undetectable. The final catalyst, D5, was thus prepared.

[0104] Comparative Example 6

[0105] The catalyst was prepared according to Example 3, except that the support was replaced with alumina particles treated at 900°C (this alumina was a self-made support from the Beijing Research Institute of Chemical Industry, with a specific surface area of ​​145.3 cm²). 2 / g, with an average mesopore diameter of 14nm and a support water absorption rate of 104%), finally yielded catalyst D6.

[0106] Test Example 1

[0107] The dispersion (%) of the active component was measured using a chemisorption analyzer. The test method was as follows: three catalyst samples were placed in a sample tube and placed in the heating mantle of the chemisorption analyzer. The instrument measured the dispersion of the particles by the adsorption of gas molecules on the surface of the nanoparticles. When the dispersion is good, the specific surface area of ​​the carrier particles will be smaller than that of the standard particles. The content of the active component (wt%) was measured using X-ray fluorescence spectroscopy (XRF). The water absorption rate (%) was tested by weighing 10g of the carrier into 100mL of deionized water, weighing the carrier after 10 minutes, and calculating the water absorption rate. The average pore size distribution (nm) and specific surface area (cm²) of the mesopores were also measured. 2 / g) and pore volume (cm) 3 The nitrogen adsorption method was used to measure the nitrogen adsorption ( / g) using a physical adsorption analyzer (BET), and the results are shown in Table 1.

[0108] Table 1

[0109]

[0110] Test Example 2

[0111] 10.00 g of the selective hydrogenation catalyst of this invention was weighed and loaded into a quartz tube furnace. High-purity N2 was introduced three times at a flow rate of 200 mL / min for replacement. The high-purity N2 was then switched to H2 at a flow rate of 200 mL / min. The temperature was increased to 200-300 °C at a rate of 5 °C / min and maintained for 3 hours to reduce the catalyst. The temperature was then slowly lowered to room temperature, and the needle valve of the tube furnace was opened to allow the catalyst to passivate under natural conditions for 1 hour. The catalyst was then unloaded. 1 g of the reduced catalyst was placed in a high-pressure reactor with 30 mL of reactants (6 mL cinnamaldehyde and 24 mL ethanol solvent). The reaction conditions are shown in Table 2, and the results are shown in Table 2.

[0112] Table 2

[0113]

[0114] As shown in Table 1, the catalysts C1-C7 provided by this invention, under the selective hydrogenation conditions described in this invention, can achieve a cinnamaldehyde conversion rate of over 99% and a phenylpropanaldehyde selectivity of over 91%. Comparing Examples 1 and 7, it was found that the content of noble metals in the catalyst within the preferred range of this invention ensures high phenylpropanaldehyde selectivity while controlling the preparation cost of noble metal catalysts. Comparing the examples and comparative examples, it was found that only the support described in this invention can effectively load the active components, and the active components have a high degree of dispersion, resulting in higher cinnamaldehyde conversion and phenylpropanaldehyde selectivity. Comparing Example 3 and Comparative Examples 3-5, it was shown that the calcination temperature of the support and the boehmite treatment method also affect the cinnamaldehyde conversion and phenylpropanaldehyde selectivity; the calcination temperature of the support and the boehmite treatment method within the range described in this invention can achieve higher cinnamaldehyde conversion and phenylpropanaldehyde selectivity. Comparing Example 3 and Comparative Example 6, it can be seen that the noble metal is loaded on a conventional alumina support. It is speculated that excessive hydrogenation will lead to a decrease in the selectivity of phenylpropionaldehyde in this invention. Therefore, only by selecting the catalyst and cinnamaldehyde selective hydrogenation method described in this invention can we obtain cinnamaldehyde with higher conversion rate and phenylpropionaldehyde with better selectivity.

[0115] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A selective hydrogenation catalyst for cinnamaldehyde, characterized in that, The catalyst comprises a support and an active component supported on the support, wherein the support is macroporous alumina with a specific surface area of ​​95-195 cm². 2 / g, the average pore size of the carrier is 20-90nm, the water absorption rate of the carrier is 205-300%, and the active component is selected from at least one of Ru, Rh, Pt and Pd.

2. The catalyst according to claim 1, wherein, Based on the total weight of the catalyst, the content of the support is 99.5-99.9% by weight, and the content of the active component is 0.1-0.5% by weight. Preferably, the carrier content is 99.6-99.8% by weight, and the active component content is 0.2-0.4% by weight.

3. The catalyst according to claim 1, wherein, The active component is selected from at least one of Ru, Rh and Pd; And / or, the average pore size of the mesopores in the carrier is 20-32 nm; And / or, the specific surface area of ​​the carrier is 95-145 cm². 2 / g; And / or, the pore volume of the carrier is 0.5-1.4 cm. 3 / g; And / or, the water absorption rate of the carrier is 210-250%; And / or, the sulfur content of the carrier is 0.01-0.19% by weight; And / or, the dispersion of the active component is 5-9%.

4. A method for preparing a selective hydrogenation catalyst for cinnamaldehyde, characterized in that, The method includes: 1) Boehmite was prepared using the sulfuric acid process; 2) The carrier is obtained by crystallizing boehmite, first drying, and first calcining at 1000-1150℃; 3) The support is impregnated in the precursor solution of the active component, and the selective hydrogenation catalyst is obtained by second drying and second calcination; The sulfur content in the boehmite is 1-3.4% by weight, and the active component is at least one of Ru, Rh, Pt and Pd.

5. The method according to claim 4, wherein, The method for preparing boehmite by the sulfuric acid process includes: mixing an alkaline sodium aluminate solution with an aluminum sulfate solution to make the pH of the system 8-10; And / or, the sodium aluminate content in the alkaline sodium aluminate is 4-21% by weight, OH - The content is 2-9% by weight; Preferably, the sodium aluminate content in the alkaline sodium aluminate is 6-12% by weight, OH - The content is 3-6% by weight; And / or, the concentration of the aluminum sulfate solution is 0.3-0.9 mol / L, preferably 0.4-0.7 mol / L; And / or, based on metal elements, the weight ratio of the active component to the carrier is 1:199-999, preferably 1:249-499; And / or, the active component is at least one of Ru, Rh and Pd.

6. The method according to claim 4, wherein, The precursor of the active component is selected from at least one of ruthenium nitrate, rhodium nitrate, platinum nitrate, palladium nitrate, ruthenium carbonate, rhodium carbonate, platinum carbonate, and palladium carbonate; Preferably, the precursor of the active component is selected from at least one of ruthenium nitrate, rhodium nitrate, palladium nitrate, ruthenium carbonate, rhodium carbonate, and palladium carbonate; Preferably, the sulfur content in the boehmite is 1.3-1.9% by weight.

7. The method according to claim 4, wherein, The crystallization conditions include: a temperature of 60-110℃ and a time of 5-24h; Preferably, the crystallization conditions include: a temperature of 70-90°C and a time of 8-13 hours; And / or, the conditions for the first drying include: a temperature of 80-160°C and a time of 1-4 hours; Preferably, the conditions for the first drying include: a temperature of 110-130°C and a time of 1.5-3 hours; And / or, the conditions for the first calcination include: a temperature of 1000-1150℃ and a time of 4-10h; Preferably, the conditions for the first calcination include: a temperature of 1000-1100℃ and a time of 5-8h.

8. The method according to claim 4, wherein, The conditions for the second drying process include: a temperature of 60-120℃ and a time of 3-12 hours; Preferably, the conditions for the second drying include: a temperature of 90-110°C and a time of 4-9 hours; And / or, the conditions for the second calcination are: a temperature of 300-400℃ and a time of 4-7h; Preferably, the conditions for the second calcination are: a temperature of 320-380℃ and a time of 5-6 hours.

9. The cinnamaldehyde selective hydrogenation catalyst prepared by the method according to any one of claims 4-8.

10. A method for the selective hydrogenation of cinnamaldehyde to prepare phenylpropionaldehyde, characterized in that, The method includes selectively hydrogenating cinnamaldehyde in the presence of the catalyst and solvent described in any one of claims 1-3 and 9.

11. The method according to claim 10, wherein, The reduction conditions for the catalyst include: H2 atmosphere, temperature of 400-500℃, and time of 4-6h; And / or, the passivation conditions for the catalyst are: natural conditions, passivation for 0.5-2 hours.

12. The method according to claim 10, wherein, The solvent may be at least one of methanol, ethanol, and propanol; And / or, relative to each gram of the above catalyst, the amount of solvent used is 15-31 mL, and the amount of cinnamaldehyde used is 4-10 mL; And / or, the selective hydrogenation reaction conditions include: a reaction temperature of 70-90°C, a reaction hydrogen pressure of 1-4 MPa, and a reaction time of 1-5 h.

13. The use of the catalyst according to any one of claims 1-3 and 9 in the selective hydrogenation of cinnamaldehyde to prepare phenylpropionaldehyde.

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