Cu / hzsm-5 molecular sieve, preparation thereof and application thereof in raspberry ketone synthesis

Abstract

The present application relates to the technical field of fine chemicals synthesis, in particular to a Cu / HZSM-5 molecular sieve, its preparation and application in raspberry ketone synthesis. The copper salt is dissolved and mixed with HZSM-5 molecular sieve, then ammonia is evaporated, and CuO / HZSM-5 molecular sieve is obtained after post-processing; then the CuO / HZSM-5 molecular sieve is subjected to hydrogen reduction treatment to obtain Cu / HZSM-5 molecular sieve. The Cu / HZSM-5 molecular sieve prepared by the present application is used as a catalyst to catalyze H2 and 4-(4-hydroxyphenyl)-3-buten-2-one to generate raspberry ketone, the catalytic efficiency is high, the conversion rate of 4-(4-hydroxyphenyl)-3-buten-2-one can reach 100%, the selectivity of raspberry ketone can reach 99.8% at most, and the present application has the advantages of low cost, high efficiency, good stability, short production cycle and the like.

Description

Technical Field

[0001] This invention relates to the field of fine chemical synthesis technology, and in particular to a Cu / HZSM-5 molecular sieve, its preparation, and its application in the synthesis of raspberry ketones. Background Technology

[0002] Raspberry ketone, also known as brassone, has the chemical name 4-p-hydroxyphenyl-2-butanone. It is a white needle-like crystal with a raspberry aroma and a sweet fruity taste. Raspberry ketone can be used to formulate food flavorings and daily-use fragrances, and is also used in the synthesis of pharmaceuticals, dyes, and insect attractants. It is also an important intermediate in fine chemicals.

[0003] Raspberry ketone has been recognized by both FEMA and COE, two of the world's leading authorities, and is also an edible flavoring that complies with GB2760-86 standards. Global consumption exceeds 2,000 tons per year.

[0004] There are four main methods for synthesizing raspberry ketones: the synthetic route of reacting phenol with methyl ketene; the synthetic route of reacting phenol with butanol ketone; the synthetic route of reacting p-methoxybenzyl chloride with ethyl acetoacetate; and the synthetic route of condensing p-hydroxybenzaldehyde with acetone and then reducing it with hydrogen.

[0005] The first three routes have disadvantages such as high toxicity of raw materials, phenol residue, many by-products, difficulty in product purification, and low yield. The fourth route has the advantages of easy product purification and high yield. Currently, Ni, Pd, and Pt catalysts are commonly used in the second reduction process. When separating nickel catalysts with alcohol solvents, they are extremely prone to ignition or even explosion, posing a significant safety risk. Pd and Pt are both precious metals and are expensive. Currently, most of the production of raspberry ketones adopts batch reactions. Batch reactions have disadvantages such as long reaction cycles, limited reaction time and yield, and poor continuous production capacity of reactors. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a Cu / HZSM-5 molecular sieve, its preparation, and its application in the synthesis of raspberry ketones. The Cu / HZSM-5 molecular sieve uses HZSM-5 molecular sieve as a support, and copper is the active component.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] The first objective of this invention is to provide a method for preparing Cu / HZSM-5 molecular sieves, comprising the following steps:

[0009] (S1) After dissolving the copper salt, mix it with HZSM-5 molecular sieve, then perform ammonia stripping treatment, and obtain CuO / HZSM-5 molecular sieve after post-treatment.

[0010] (S2) The CuO / HZSM-5 molecular sieve prepared in step (S1) is subjected to hydrogenation reduction treatment to obtain Cu / HZSM-5 molecular sieve with a Cu loading of 10-20%;

[0011] Among them, Cu / HZSM-5 molecular sieve contains Cu + With Cu 0 .

[0012] In one embodiment of the present invention, in step (S1), the copper salt is selected from one or more of copper nitrate trihydrate, copper sulfate pentahydrate, or copper chloride dihydrate;

[0013] In HZSM-5 molecular sieve, the n(SiO2) / n(Al2O3) ratio is 50–300, and its BET specific surface area is 380–415 m². 2 / g.

[0014] In one embodiment of the present invention, copper salt is dissolved in water, and the pH is adjusted to 10-11 using ammonia water with a concentration of 25-28 wt%.

[0015] In one embodiment of the present invention, in step (S1), the mixing process is carried out at a temperature of 40-60°C for 4-5 hours.

[0016] During the ammonia stripping process, the temperature is 85–100℃, and the ammonia stripping process continues until the solution pH reaches 6.5–7.5.

[0017] In one embodiment of the present invention, step (S1) involves sequentially performing filtration, washing, drying, calcination, grinding, and sieving.

[0018] In one embodiment of the present invention, the drying process is carried out at a temperature of 110–120°C for 10–12 hours.

[0019] During the roasting process, the temperature is 300-400℃ and the time is 3-4 hours; preferably, the roasting temperature is 350℃.

[0020] During the sieving process, the mesh size of the sieve is 20 to 30.

[0021] In one embodiment of the present invention, in step (S2), during the hydrogenation reduction process, the reducing hydrogen pressure is 0.10 MPa, the reduction temperature is 250-300°C, and the reduction time is 3-5 h.

[0022] Preferably, during the hydrogenation reduction process, the reduction temperature is 275°C and the reduction time is 4 hours.

[0023] The second objective of this invention is to provide a Cu / HZSM-5 molecular sieve, which is prepared by the above method.

[0024] The third objective of this invention is to provide an application of Cu / HZSM-5 molecular sieve in the synthesis of raspberry ketones, comprising the following steps:

[0025] After dissolving 4-(4-hydroxyphenyl)-3-buten-2-one (4-HPB), hydrogenation was carried out under a hydrogen atmosphere using Cu / HZSM-5 molecular sieve as a catalyst to obtain raspberry ketone.

[0026] In one embodiment of the present invention, 4-(4-hydroxyphenyl)-3-buten-2-one (4-HPB) is dissolved in an organic solvent (selected from n-butanol or isobutanol) to obtain a 4-HPB solution, wherein the mass percentage of 4-HPB in the 4-HPB solution is 18-22%.

[0027] In one embodiment of the present invention, the ratio of hydrogen, 4-HPB and Cu / HZSM-5 molecular sieve is 8-12 mol: 1 mol: 2-6 g;

[0028] Preferably, the ratio of hydrogen, 4-HPB and Cu / HZSM-5 molecular sieve is 10 mol: 1 mol: 5 g.

[0029] In one embodiment of the present invention, the temperature during the hydrogenation reaction is 80–100°C.

[0030] Cu / HZSM-5 molecular sieve catalysts prepared by the ammonia stripping method exhibit small Cu particle sizes and high dispersion on the surface of the HZSM-5 support under low copper loading (10%–20%). However, under high copper loading (30%–40%), Cu particles agglomerate, resulting in larger particle sizes and poorer dispersibility on the HZSM-5 support surface. Furthermore, Cu / HZSM-5 catalysts prepared by the ammonia stripping method contain Cu... + Cu + Promotes H2 decomposition, Cu + With Cu 0 The synergistic effect between them improves the activity and stability of the catalyst. When the metal particle size is small, the steric hindrance effect caused by the benzene ring is not obvious, and both C=C and C=O double bonds can contact the metal surface. In this case, C=C hydrogenation is dominant. The density of acid centers on the HZSM-5 surface decreases with the increase of the silicon-aluminum ratio, which is beneficial to the hydrogenation of C=C double bonds in α,β-unsaturated ketones.

[0031] This invention employs a continuous catalytic reduction synthesis of raspberry ketones, utilizing a Cu / HZSM-5 supported multi-stage catalyst in the reaction. Cu(3d) 10 4s 1The d orbital bandwidth of copper is relatively small, making it the optimal active component for the selective hydrogenation of the C=C double bond in α,β-unsaturated ketones to saturated ketones. Furthermore, elemental copper supported on the molecular sieve HZSM-5 is converted to copper hydride at 80–100 °C. Copper hydride exhibits high activity for the selective hydrogenation of the C=C double bond in α,β-unsaturated ketones. The synthetic route is as follows:

[0032]

[0033] The reaction process is as follows:

[0034] Cu represents the catalyst. Hydrogen molecules break bonds on the catalyst, transforming into activated hydrogen atoms. The catalyst also causes the adsorbed olefin to break its double bonds before hydrogenation, generating a double free radical. The activated hydrogen atom combines with the double free radical to form a carbon free radical, which then combines with the activated hydrogen atom to complete the hydrogenation process of the double bond and leaves the catalyst surface, thus completing the hydrogenation reaction.

[0035]

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) In this invention, the Cu / HZSM-5 molecular sieve uses HZSM-5 as a carrier and copper as an active component. HZSM-5 as a carrier has the advantages of good corrosion resistance, precise selectivity and good hydrothermal stability. Copper as an active component replaces the use of precious metals such as palladium and platinum, which reduces production costs. In general, the preparation process of the Cu / HZSM-5 molecular sieve of this invention is low-cost and environmentally friendly.

[0038] (2) The Cu / HZSM-5 molecular sieve in this invention has the advantages of high activity, high product selectivity, high raw material conversion rate, stable activity, and long service life.

[0039] (3) When the Cu / HZSM-5 molecular sieve of the present invention is used as a catalyst to catalyze the generation of raspberry ketone, the continuous reaction has the advantages of high efficiency, good stability, short production cycle, high yield, simple process, low energy consumption, and green environmental protection, and is suitable for industrial production. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the reaction apparatus used in this invention;

[0041] Figure 2 TEM image of Cu / HZSM-5 molecular sieve prepared in Example 1;

[0042] Labels in the diagram: 1. Raw material tank; 2. Metering pump; 31. First pressure gauge; 32. Second pressure gauge; 4. Hydrogen cylinder; 5. Hydrogen quality control valve; 6. Three-way valve; 7. Heating mantle; 81. First thermometer; 82. Second thermometer; 83. Third thermometer; 9. Fixed bed reactor; 10. Back pressure valve; 11. Gas-liquid separator; 12. Discharge valve; 13. Reaction tube. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0044] Unless otherwise specified, all reagents used in the following embodiments are commercially available reagents, and all detection methods and techniques used are conventional detection methods and techniques in the art.

[0045] In the following embodiments, the gas chromatography column was TM-1 30m × 0.25mm × 0.25um, and the external standard method was used for analysis.

[0046] Conversion rate of 4-HPB = number of moles of 4-HPB that have reacted / initial number of moles of 4-HPB;

[0047] Selectivity of raspberry ketone = number of moles of raspberry ketone produced / number of moles of 4-HPB converted.

[0048] In the following embodiments, the reaction apparatus used is as follows: Figure 1 As shown, it includes a raw material tank 1, a hydrogen cylinder 4, a three-way valve 6, a fixed-bed reactor 9, and a gas-liquid separator 11;

[0049] The three-way valve 6 is connected to the raw material tank 1, the hydrogen cylinder 4, and the fixed-bed reactor 9 via pipelines. A metering pump 2 and a first pressure gauge 31 (the metering pump 2 is located near the raw material tank 1, and the first pressure gauge 31 is located near the three-way valve 6) are installed on the pipeline connecting the raw material tank 1 and the three-way valve 6. A second pressure gauge 32 and a hydrogen quality control valve 5 (the second pressure gauge 32 is located near the hydrogen cylinder 4, and the hydrogen quality control valve 5 is located near the three-way valve 6) are installed on the pipeline connecting the hydrogen cylinder 4 and the three-way valve 6. The fixed-bed reactor 9 is connected to the three-way valve 6. An electric heating jacket 7 is installed on the connected pipeline for heating the pipeline. A reaction tube 13 is installed inside the fixed bed reactor 9. A thermometer is installed on the reaction tube 13 to monitor the temperature at each position of the reaction tube (the temperature at the inlet position (first thermometer 81), the outlet position (second thermometer 82), and the middle position (third thermometer 83) of the reaction tube 13 respectively). A back pressure valve 10 is installed on the pipeline connecting the fixed bed reactor 9 and the gas-liquid separator 11. One outlet of the gas-liquid separator 11 is used to transport gas, and the other outlet is used to transport liquid. A discharge valve 12 is installed on the pipeline for transporting liquid.

[0050] Example 1

[0051] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieves, the specific steps of which are as follows:

[0052] Dissolve 9.51 g of copper nitrate trihydrate in 60 g of distilled water to obtain a copper nitrate aqueous solution. Add 26% ammonia dropwise with stirring until the pH reaches 10.5. Heat to 50°C and add 10.0 g of molecular sieve HZSM-5 (silicon-to-aluminum ratio n(SiO2) / n(Al2O3) = 200) with stirring, continuing stirring for 5 hours. Then heat to 90°C to evaporate ammonia until the solution pH reaches 7. Filter, and wash the filter cake with distilled water until no NO3 is detected. - The catalyst was dried at 115℃ for 11 hours, then calcined at 350℃ for 3.5 hours, ground, and passed through a 20-30 mesh sieve to obtain 20% CuO / HZSM-5(200).

[0053] Adopting such Figure 1 The experiment was conducted using the experimental setup shown. 20% CuO / HZSM-5(200) was loaded into the isothermal zone of reaction tube 13 inside the fixed-bed reactor 9. The hydrogen mass control valve 5 was opened, and the reducing hydrogen pressure was set to 0.10 MPa using the second pressure gauge 3. The heating mantle 7 was turned on, and the temperatures monitored by the thermometers (first thermometer 81, second thermometer 82, and third thermometer 83) were observed. The intermediate temperature of reaction tube 13 inside the fixed-bed reactor 9 was controlled at 275℃ (the temperature monitored by the third thermometer 83). The reduction treatment lasted for 4.5 hours, resulting in a 20% Cu / HZSM-5(200) molecular sieve catalyst (abbreviated as 20Cu-Z(200)). Here, 20% indicates that the mass fraction of Cu in the Cu / HZSM-5 molecular sieve is 20%.

[0054] Example 2

[0055] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieve. Compared with Example 1, except for the addition of HZSM-5 (silicon-to-aluminum ratio of n(SiO2) / n(Al2O3) = 50), all other steps are the same. The resulting product is 20Cu-Z(50).

[0056] Example 3

[0057] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieves. Compared with Example 1, except for the addition of HZSM-5 (with a silicon-to-aluminum ratio of n(SiO2) / n(Al2O3) of 150), all other steps are the same. The resulting material is 20Cu-Z(150).

[0058] Example 4

[0059] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieves. Compared with Example 1, except for the addition of HZSM-5 (with a silicon-to-aluminum ratio of n(SiO2) / n(Al2O3) of 300), all other steps are the same. The resulting material is 20Cu-Z(300).

[0060] The molecular sieves prepared in Examples 1-4 were used as catalysts (placed in the isothermal zone of reaction tube 13 of fixed-bed reactor 9) for hydrogenation reaction. 4-HPB was dissolved in n-butanol (4-HPB concentration of 20 wt%) and placed in raw material tank 1. A metering pump 2 was used to feed 0.58 mL / min of 4-HPB solution (containing 0.00062 mol of 4-HPB) from raw material tank 1 into the reaction system. At the same time, hydrogen cylinder 4 was opened to control the hydrogen pressure. The 4-HPB solution and H2 were mixed at three-way valve 6 and preheated by electric heating mantle 7 before entering reaction tube 13 in fixed-bed reactor 9 for hydrogenation reaction (the temperature inside reaction tube 13 was detected by thermometer). The reaction product came out from the bottom of fixed-bed reactor 9 and entered gas-liquid separator 11 through back pressure valve 10 to separate the product raspberry ketone, which was then released through discharge valve 12. After the reaction system stabilized, the product was analyzed by gas phase.

[0061] The reaction conditions were as follows: catalyst dosage 5.0 g, H2 / 4-HPB molar ratio 10.0:1.0, reaction temperature 90℃, reaction pressure 0.20 MPa, and liquid hourly space velocity 1.2 h⁻¹. -1 After 20 hours of operation, samples were taken for gas-phase analysis. The specific catalytic efficiency is as follows:

[0062] Table 1. Effect of Si to Al molar ratio on the reaction in HZSM-5

[0063] Example 2 20Cu-Z(50) 97.8 97.2 Example 3 20Cu-Z(150) 98.5 98.1 Example 1 20Cu-Z(200) 100.0 99.5 Example 4 20Cu-Z(300) 100.0 99.6

[0064] Table 1 shows that the catalytic efficiency is highest when the silicon-to-aluminum ratio (n(SiO2) / n(Al2O3)) of the molecular sieve catalyst is 200, with a conversion rate of 100.0% for 4-HPB and a selectivity of 99.5% for raspberry ketone. In subsequent investigations into the effect of Cu loading on the reaction, the n(SiO2) / n(Al2O3) ratio of the molecular sieve catalyst was consistently 200.

[0065] Example 5

[0066] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieves, the specific steps of which are as follows:

[0067] 4.18 g of copper nitrate trihydrate was dissolved in 40 g of distilled water to obtain a copper nitrate aqueous solution. 26% ammonia solution was added dropwise with stirring until the pH reached 10.5. The solution was then heated to 50°C and 10.0 g of molecular sieve HZSM-5 (n(SiO2) / n(Al2O3) = 200) was added with stirring for 5 hours. The temperature was then raised to 90°C to evaporate the ammonia until the solution pH reached 7. The solution was filtered, and the filter cake was washed with distilled water until no NO3 was detected. - The catalyst was dried at 115℃ for 11 hours, then calcined at 350℃ for 3.5 hours, ground, and passed through a 20-30 mesh sieve to obtain 10% CuO / HZSM-5(200).

[0068] Adopting such Figure 1 The experiment was conducted using the experimental setup shown. 10% CuO / HZSM-5(200) was loaded into the isothermal zone of the reaction tube 13 inside the fixed-bed reaction tube 9. The hydrogen mass control valve 5 was opened, and the reduction hydrogen pressure was set to 0.10 MPa using the second pressure gauge 3. The heating mantle 7 was turned on, and the temperature monitored by the thermometers (first thermometer 81, second thermometer 82, and third thermometer 83) was checked. The temperature in the middle of the reaction tube inside the fixed-bed reactor 9 was controlled to be 275℃ (the temperature monitored by the third thermometer 83), and the reduction time was 4.5 h, resulting in 10Cu-Z(200).

[0069] Example 6

[0070] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieves, the specific steps of which are as follows:

[0071] 16.31 g of copper nitrate trihydrate was dissolved in 100.0 g of distilled water to obtain a copper nitrate aqueous solution. 26% ammonia solution was added dropwise with stirring until the pH reached 10.5. The solution was then heated to 50°C and 10.0 g of molecular sieve HZSM-5 (n(SiO2) / n(Al2O3) = 200) was added with stirring, and stirring continued for 4.5 h. Then, the temperature was raised to 90°C to evaporate the ammonia until the solution pH reached 7. The solution was filtered, and the filter cake was washed with distilled water until no NO3 was detected. - The catalyst was dried at 115℃ for 11 hours, then calcined at 350℃ for 3.5 hours, ground, and passed through a 20-30 mesh sieve to obtain 30% CuO / HZSM-5(200).

[0072] Adopting such Figure 1The experiment was conducted using the experimental setup shown. 30% CuO / HZSM-5(200) was loaded into the isothermal zone of the reaction tube 13 inside the fixed-bed reactor tube 9. The hydrogen mass control valve 5 was opened, and the reducing hydrogen pressure was set to 0.10 MPa using the second pressure gauge 3. The heating mantle 7 was turned on, and the temperature monitored by the thermometers (first thermometer 81, second thermometer 82, and third thermometer 83) was observed. The intermediate temperature of the reaction tube 13 inside the fixed-bed reactor 9 was controlled at 275℃ (the temperature monitored by the third thermometer 83), and the reduction time was 4.5 h, resulting in 30Cu-Z(200).

[0073] Example 7

[0074] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieves, the specific steps of which are as follows:

[0075] 25.36 g of copper nitrate trihydrate was dissolved in 135.0 g of distilled water to obtain a copper nitrate aqueous solution. 26% ammonia solution was added dropwise with stirring until the pH reached 10.5. The solution was then heated to 50°C and 10.0 g of molecular sieve HZSM-5 (n(SiO2) / n(Al2O3) = 200) was added with stirring, and stirring continued for 4.5 h. Then, the temperature was raised to 90°C to evaporate the ammonia until the solution pH reached 7. The solution was filtered, and the filter cake was washed with distilled water until no NO3 was detected. - The catalyst was dried at 115℃ for 11 hours, then calcined at 350℃ for 3.5 hours, ground, and passed through a 20-30 mesh sieve to obtain 40% CuO / HZSM-5(200).

[0076] Adopting such Figure 1 The experiment was conducted using the experimental setup shown. 40% CuO / HZSM-5(200) was loaded into the isothermal zone of the reaction tube 13 inside the fixed-bed reactor 9. The hydrogen mass control valve 5 was opened, and the reducing hydrogen pressure was set to 0.10 MPa using the second pressure gauge 3. The heating mantle 7 was turned on, and the temperature monitored by the thermometers (first thermometer 81, second thermometer 82, and third thermometer 83) was observed. The intermediate temperature of the reaction tube 13 inside the fixed-bed reactor 9 was controlled at 275℃ (the temperature monitored by the third thermometer 83), and the reduction time was 4.5 h, resulting in 40Cu-Z(200).

[0077] Example 8

[0078] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieves. Compared with Example 1, the only difference is that the copper source is replaced with copper sulfate pentahydrate with the same copper content, and SO4 is removed during washing. 2- Wash it clean.

[0079] Example 9

[0080] This embodiment provides a method for preparing Cu / HZSM-5 molecular sieves. Compared with Example 1, the only difference is that the copper source is replaced with copper chloride dihydrate with the same copper content, and during the washing process, Cl... - Wash it clean.

[0081] The molecular sieves prepared in Examples 1 and 5-7 were used as catalysts (placed in the isothermal zone of reaction tube 13 of fixed-bed reactor 9) for hydrogenation reaction. 4-HPB was dissolved in n-butanol (4-HPB concentration of 20 wt%) and placed in raw material tank 1. A metering pump 2 was used to feed 0.58 mL / min of 4-HPB solution (containing 0.00062 mol of 4-HPB) from raw material tank 1 into the reaction system. At the same time, hydrogen cylinder 4 was opened to control the hydrogen pressure. The 4-HPB solution and H2 were mixed at three-way valve 6 and preheated by electric heating mantle 7 before entering reaction tube 13 in fixed-bed reactor 9 for hydrogenation reaction (the temperature inside reaction tube 13 was detected by thermometer). The reaction product came out from the bottom of fixed-bed reactor 9 and entered gas-liquid separator 11 through back pressure valve 10 to separate the product raspberry ketone, which was then released through discharge valve 12. After the reaction system stabilized, the product was analyzed by gas phase.

[0082] The reaction conditions were as follows: catalyst dosage 5.0 g, H2 / 4-HPB molar ratio 10.0:1.0, reaction temperature 90℃, reaction pressure 0.20 MPa, and liquid hourly space velocity 1.2 h⁻¹. -1 After 20 hours of operation, samples were taken for gas-phase analysis. The specific catalytic efficiency is as follows:

[0083] Table 2 Effect of Cu loading in catalyst on reaction

[0084] Example 5 10Cu-Z(200) 85.0 100.0 Example 1 20Cu-Z(200) 100.0 99.5 Example 6 30Cu-Z(200) 100.0 90.0 Example 7 40Cu-Z(200) 100.0 85.5

[0085] In Cu-Z(200) catalyst, the conversion rate of 4-HPB increases with the increase of Cu loading. When the Cu loading is 20wt%, the conversion rate of 4-HPB reaches 100%. However, with the increase of Cu loading, the number of active particles increases, which will promote the occurrence of deep hydrogenation reaction and lead to a decrease in the selectivity of the reaction. Therefore, 20Cu-Z(200) catalyst is better.

[0086] Example 10

[0087] In this embodiment, the molecular sieve catalyst 20Cu-Z(200) prepared in Example 1 was used in an amount of 5.0 g and the reaction was carried out for 20 h. The reaction results under different H2 / 4-HPB ratios, reaction temperatures, reaction pressures and liquid hourly space velocities are shown in Table 3.

[0088] Table 3. Reaction of molecular sieve catalyst 20Cu-Z(200) under different conditions

[0089]

[0090]

[0091] Using a 20Cu-Z(200) catalyst, the conversion rate increased with increasing H2 / 4-HPB molar ratio, with a suitable H2 / 4-HPB molar ratio of 10. Further increases in the molar ratio did not improve either the conversion rate or the selectivity. With increasing reaction temperature, the conversion rate increased, but the selectivity decreased, with a suitable reaction temperature of 90℃. The reaction pressure was similar to the reaction temperature, with a suitable pressure of 0.20 MPa. With increasing liquid hourly space velocity (LHSV), the conversion rate decreased, while the selectivity did not improve significantly; a LHSV of 1.2 h⁻¹ was suitable. -1 The reaction was suitable. Catalyst 20Cu-Z(200) was used at a dosage of 5.0 g, the H₂ / ₄-HPB molar ratio was 10.0:1.0, the reaction temperature was 90℃, the reaction pressure was 0.20 MPa, and the liquid hourly space velocity was 1.2 h⁻¹. -1 The conversion rate of the reaction was 100%, and the selectivity of the reaction was 99.5%.

[0092] Example 11

[0093] This embodiment uses the molecular sieve catalyst 20Cu-Z(200) prepared in Example 1, with an amount of 5.0 g, an H2 / 4-HPB molar ratio of 10.0:1.0, a reaction temperature of 90℃, a reaction pressure of 0.20 MPa, and a liquid hourly space velocity of 1.2 h⁻¹. -1 The hydrogenation reaction was carried out for 500 hours. The results are shown in Table 4.

[0094] Table 4. Stability test results of molecular sieve catalyst 20Cu-Z(200)

[0095] Conversion rate (%) 97.4 100.0 100.0 100.0 99.8 99.6 98.8 97.8 97.4 96.3 Selectivity (%) 99.2 99.5 99.5 99.4 99.1 99.0 98.6 97.0 96.4 94.7

[0096] It can be seen that the molecular sieve catalyst 20Cu-Z(200) has good activity stability.

[0097] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. An application of Cu / HZSM-5 molecular sieve in the synthesis of raspberry ketones, characterized in that, Includes the following steps: After dissolving 4-(4-hydroxyphenyl)-3-buten-2-one, hydrogenation was carried out under a hydrogen atmosphere using Cu / HZSM-5 molecular sieve as a catalyst to obtain raspberry ketone. The preparation method of Cu / HZSM-5 molecular sieve includes the following steps: (S1) After dissolving the copper salt, mix it with HZSM-5 molecular sieve, then perform ammonia stripping treatment, and obtain CuO / HZSM-5 molecular sieve after post-treatment. (S2) The CuO / HZSM-5 molecular sieve prepared in step (S1) is subjected to hydrogenation reduction treatment to obtain Cu / HZSM-5 molecular sieve with a Cu loading of 10~20%; Among them, Cu / HZSM-5 molecular sieve contains Cu + With Cu 0 ; In HZSM-5 molecular sieve, the n(SiO2) / n(Al2O3) ratio is 50~300, and its BET specific surface area is 380~415 m². 2 / g; During the ammonia stripping process, the temperature is 85~100℃, and the ammonia stripping process continues until the solution pH is 6.5~7.

5.

2. The application according to claim 1, characterized in that, In step (S1), the copper salt is selected from one or more of copper nitrate trihydrate, copper sulfate pentahydrate, or copper chloride dihydrate.

3. The application according to claim 1, characterized in that, In step (S1), the mixing process is carried out at a temperature of 40~60℃ for 4~5 hours.

4. The application according to claim 1, characterized in that, In step (S1), the post-processing involves sequentially performing filtration, washing, drying, calcination, grinding, and sieving.

5. The application according to claim 4, characterized in that, During the drying process, the temperature is 110~120℃ and the time is 10~12h; During the roasting process, the temperature is 300~400℃ and the time is 3~4 hours; During the sieving process, the mesh size of the sieve is 20-30.

6. The application according to claim 1, characterized in that, In step (S2), during the hydrogenation reduction process, the reducing hydrogen pressure is 0.10 MPa, the reduction temperature is 250~300℃, and the reduction time is 3~5 h.

7. The application according to claim 1, characterized in that, The ratio of hydrogen, 4-(4-hydroxyphenyl)-3-buten-2-one to Cu / HZSM-5 molecular sieve is 8~12 mol: 1 mol: 2~6 g.

8. The application according to claim 1, characterized in that, During the hydrogenation reaction, the temperature is 80~100℃.

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