Method for preparing high-purity myricetin by catalysis of molecular sieve

Abstract

The application discloses a method for preparing high-purity myricetin by using a molecular sieve catalyst, and relates to the technical field of medicine and chemical industry. The method comprises the following steps: step S1, raw material pretreatment; step S2, multi-energy field assisted leaching; step S3, molecular sieve catalysis; and step S4, purification. The method for preparing high-purity myricetin by using a molecular sieve catalyst can safely and efficiently prepare high-purity myricetin with high yield.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medicine and chemical industry, and particularly relates to a method for preparing high-purity myricetin by catalysis of molecular sieve. BACKGROUND

[0002] Myricetin, also known as myricitrin and myricetin, is a flavonoid compound extracted from the fruit of Myrica rubra. It has multiple functions such as scavenging free radicals, antioxidant, anti-tumor, reducing neurotoxicity, affecting lymphocyte activation and proliferation, anti-platelet activation factor, reducing blood sugar, relieving alcohol poisoning, preventing alcoholic liver and fatty liver, inhibiting liver cell deterioration, reducing the incidence of liver cancer, protecting liver, and anti-inflammatory. It can also strongly inhibit yeast alpha-glucosidase, glucosidase I, in vitro glucosidase I and xanthine oxidase in milk.

[0003] Myricetin exists in the cell content. The extraction method generally uses the good penetration of alcohol to dissolve it outside the cell. However, there are a large amount of fibers in Myrica rubra and other plants, and the cell wall is composed of lignin, cellulose and pectin. They all affect the dissolution rate of myricetin and reduce the extraction efficiency of myricetin. Moreover, myricetin exists in the form of myricitrin in natural plants. Simple ethanol extraction cannot convert myricitrin in plants into myricetin, so the extraction rate of myricetin is low.

[0004] Molecular sieve is a kind of hydrated silicate of aluminum (zeolite) with the function of screening molecules, which is artificially synthesized or naturally occurring. Molecular sieve has ion exchange performance, uniform molecular size channel, excellent acid catalytic activity, good thermal stability and hydrothermal stability, and can be made into catalysts with high activity and selectivity for many reactions. It has high potential application value in the catalytic preparation of high-purity myricetin. However, there is no report on the preparation of myricetin by catalysis of molecular sieve in the prior art. SUMMARY

[0005] The main purpose of the present application is to provide a method for safely and efficiently preparing high-purity myricetin with high yield. The method uses Myrica rubra pomace as raw material, and uses molecular sieve catalysis combined with multi-field assisted extraction to greatly improve the purity and extraction rate of myricetin. The method is simple in process, convenient in operation, green in environment and pollution-free.

[0006] In order to achieve the above purpose, the present application provides a method for preparing high-purity myricetin by catalysis of molecular sieve, which comprises the following steps:

[0007] Step S1, pretreatment of raw material: the Myrica rubra pomace obtained after the fresh Myrica rubra is pitted and juiced is dried to constant weight at a temperature of 65-80 DEG C, and then crushed to a certain mesh size to obtain Myrica rubra pomace powder;

[0008] Step S2, multi-energy field assisted extraction: the powder of waxberry pomace prepared in step S1 is added with ethanol aqueous solution, and then is refluxed for 3-6 times under the assistance of multi-energy field; the filtrates are combined, and then the ethanol aqueous solution is removed by rotary evaporation; and then the extract is obtained by freeze-drying;

[0009] Step S3, molecular sieve catalysis: the extract is dissolved in a solvent to form a solution, and then molecular sieve is added into the solution and uniformly dispersed; the solution is placed in a polytetrafluoroethylene-lined hydrothermal reactor, and then is subjected to hydrothermal reaction at 100-150℃ for 4-6h; after the reaction is completed, the hydrothermal reactor is cooled to room temperature, and then the reaction solution is centrifuged; the supernatant is filtered, and then the solvent is removed by rotary evaporation to obtain the crude myricetin;

[0010] Step S4, purification: the crude myricetin prepared in step S3 is dissolved in an ethanol solution with a mass percentage of 28-38%, and then is filtered; the filtrate is subjected to adsorption by an adsorption column (50×6cm) filled with macroporous resin D101, and then is eluted with an ethanol solution with a mass percentage of 20-40%; the eluate is discarded; and then the crude myricetin is eluted with an ethanol solution with a mass percentage of 55-70%; the eluate is collected, and then the ethanol solution is removed by rotary evaporation; and then the crude myricetin is dried at 52-60℃ until the weight is constant to obtain the myricetin.

[0011] Preferably, the mesh number in step S1 is 20-80.

[0012] Preferably, the mass ratio of the powder of waxberry pomace to the ethanol aqueous solution in step S2 is 1:(8-12).

[0013] Preferably, the mass percentage of the ethanol aqueous solution in step S2 is 70-90%.

[0014] Preferably, the multi-energy field assistance in step S2 includes ultrasonic treatment, microwave treatment and steady magnetic field treatment.

[0015] Preferably, the ultrasonic frequency of the ultrasonic treatment is 70-100kHz, and the power is 600-1000 W; the microwave frequency of the microwave treatment is 2.5-3.0 GHz, and the power is 1000-1600 W; and the steady magnetic field strength of the steady magnetic field treatment is 0.3-2.3T.

[0016] Preferably, the mass ratio of the extract to the solvent to the molecular sieve in step S3 is 1:(5-8):(0.8-1.2).

[0017] Preferably, the solvent in step S3 is an ethanol aqueous solution with a mass percentage of 93-96%.

[0018] Preferably, the molecular sieve in step S3 is a mixture of MCM-48 molecular sieve, ZSM-8 molecular sieve and SSZ-13 molecular sieve in a mass ratio of 1:2:1.

[0019] Preferably, the mass ratio of the crude myricetin and the ethanol solution in step S4 is 1:(5-8).

[0020] Thanks to the above technical solution, the present application has the following advantages:

[0021] (1) The method for preparing high-purity myricetin by molecular sieve catalysis disclosed in the present application can safely and efficiently prepare high-purity myricetin with high yield; the method uses myrica fruit residues as raw materials, and combines molecular sieve catalysis and multi-energy field assisted extraction to greatly improve the purity and extraction rate of myricetin. The method is simple in process, easy to operate, low in energy consumption, green, environmentally friendly and pollution-free, high in preparation efficiency and product qualification rate, and suitable for continuous large-scale production.

[0022] (2) The method for preparing high-purity myricetin by molecular sieve catalysis disclosed in the present application uses myrica fruit residues as raw materials to prepare myricetin, improves the utilization rate and added value of myrica fruit residues, a by-product of agricultural and sideline products, solves the problem of environmental pollution, extends the myrica processing industry chain, realizes the transformation of waste into treasure, and realizes the good organic unity of economic benefit, social benefit and ecological benefit.

[0023] (3) The method for preparing high-purity myricetin by molecular sieve catalysis disclosed in the present application adopts multi-energy field assisted leaching, which can effectively improve the leaching efficiency and extraction rate under the action of multi-energy field, reduce the decomposition of effective components in the leaching process, and thus improve the extraction rate and purity of the product.

[0024] (4) The method for preparing high-purity myricetin by molecular sieve catalysis disclosed in the present application uses molecular sieve catalysis, and the molecular sieve is a mixture of MCM-48 molecular sieve, ZSM-8 molecular sieve and SSZ-13 molecular sieve in a mass ratio of 1:2:1; by reasonably selecting the types and compositions of the molecular sieve, the catalytic efficiency is improved, the reaction selectivity is improved, and thus the extraction rate and purity of myricetin are improved.

[0025] (5) The method for preparing high-purity myricetin by molecular sieve catalysis disclosed in the present application does not use toxic and harmful organic solvents, so that the purity of the prepared myricetin is higher, the solvent recovery and utilization are more convenient, and the preparation and consumption are safer and more environmentally friendly. In the purification process, by reasonably selecting the purification process parameters, the product purity can be further improved, and the process flow is simplified. DETAILED DESCRIPTION

[0026] The following description is presented to enable any person skilled in the art to practice the application as claimed. The preferred embodiments disclosed herein are only examples of the application and alternative variations could be adopted by one skilled in the art without departing from the spirit and scope of the application. Example 1

[0027] A method for preparing high-purity myricetin by molecular sieve catalysis, comprising the following steps:

[0028] Step S1, raw material pretreatment: the pomace obtained after the fresh waxberry is cored and juiced is dried to a constant weight at a temperature of 65℃, then crushed to a certain mesh size to obtain pomace powder;

[0029] Step S2, multi-energy field assisted extraction: the pomace powder prepared in step S1 is added with an ethanol aqueous solution, and reflux extraction is performed for 3 times under the assistance of multi-energy field. The filtrates are combined, and the ethanol aqueous solution is removed by rotary evaporation. After freeze-drying, an extract is obtained;

[0030] Step S3, molecular sieve catalysis: the extract is dissolved in a solvent to form a solution, then molecular sieve is added to the solution, and after uniform dispersion, the solution is placed in a polytetrafluoroethylene-lined hydrothermal reaction kettle, and hydrothermal reaction is performed at 100℃ for 4h. After the reaction is completed, the hydrothermal reaction kettle is cooled to room temperature, and the reaction liquid is centrifuged. After the supernatant is filtered, the solvent is removed by rotary evaporation to obtain crude myricetin;

[0031] Step S4, purification: the crude myricetin prepared in step S3 is dissolved in an ethanol solution with a mass percentage concentration of 28%, and after filtration, the filtrate is adsorbed by an adsorption column (50x6cm) filled with macroporous resin D101, then eluted with an ethanol solution with a mass percentage concentration of 20%, and the eluate is discarded. Then, the eluate is collected by eluting with an ethanol solution with a mass percentage concentration of 55%, and the ethanol solution is removed by rotary evaporation. After drying at 52℃ to a constant weight, myricetin is obtained.

[0032] In step S1, the certain mesh size is 20 mesh; in step S2, the mass ratio of the pomace powder to the ethanol aqueous solution is 1:8; in step S2, the mass percentage concentration of the ethanol aqueous solution is 70%; the multi-energy field assistance in step S2 includes ultrasonic treatment, microwave treatment and steady magnetic field treatment; the ultrasonic treatment has an ultrasonic frequency of 70kHz and a power of 600W; the microwave treatment has a microwave frequency of 2.5GHz and a power of 1000W; the steady magnetic field treatment has a steady magnetic field strength of 0.3T.

[0033] The extract, solvent and molecular sieve in step S3 are in a mass ratio of 1:5:0.8; the solvent in step S3 is an ethanol aqueous solution with a mass percentage of 93%; the molecular sieve in step S3 is a mixture of MCM-48 molecular sieve, ZSM-8 molecular sieve and SSZ-13 molecular sieve in a mass ratio of 1:2:1; and the mass ratio of the crude myricetin to the ethanol solution in step S4 is 1:5.

[0034] It is detected that the purity of the myricetin prepared by the method is 99.79%, and the extraction rate is 96.3%, wherein the extraction rate = (the mass of the crude myricetin × the purity) ÷ (the mass of the Yangmei pomace powder × the percentage of myricetin in the Yangmei pomace powder) × 100%. Example 2

[0035] A method for preparing high-purity myricetin catalyzed by a molecular sieve, comprising the following steps:

[0036] Step S1, raw material pretreatment: drying the Yangmei pomace obtained after the fresh Yangmei is juiced at a temperature of 70℃ to a constant weight, and then crushing the pomace to a certain mesh size to obtain Yangmei pomace powder;

[0037] Step S2, multi-energy field assisted extraction: adding an ethanol aqueous solution to the Yangmei pomace powder prepared in step S1, and refluxing and extracting the mixture for 4 times under the assistance of a multi-energy field, combining the filtrates, removing the ethanol aqueous solution by rotary evaporation, and then freeze-drying to obtain an extract;

[0038] Step S3, molecular sieve catalysis: dissolving the extract in a solvent to form a solution, then adding a molecular sieve to the solution, uniformly dispersing the molecular sieve, and then placing the solution in a polytetrafluoroethylene-lined hydrothermal reactor, and hydrothermally reacting at 115℃ for 4.5h; after the reaction is completed, the hydrothermal reactor is cooled to room temperature, the reaction liquid is centrifuged, the supernatant is filtered, and the solvent is removed by rotary evaporation to obtain a crude myricetin;

[0039] Step S4, purification: dissolving the crude myricetin prepared in step S3 in an ethanol solution with a mass percentage of 31%, filtering, and then adsorbing the filtrate with an adsorption column (50×6cm) filled with macroporous resin D101, eluting with an ethanol solution with a mass percentage of 25%, and discarding the eluate; then eluting with an ethanol solution with a mass percentage of 60%, collecting the eluate, removing the ethanol solution by rotary evaporation, and drying at 54℃ to a constant weight to obtain myricetin.

[0040] The mesh number in step S1 is 40; the mass ratio of the waxberry pomace powder to the ethanol aqueous solution in step S2 is 1:9; the mass percentage concentration of the ethanol aqueous solution in step S2 is 75%; the multi-energy field assisted action in step S2 includes ultrasonic treatment, microwave treatment and steady magnetic field treatment; the ultrasonic frequency of the ultrasonic treatment is 80 kHz, and the power is 700 W; the microwave frequency of the microwave treatment is 2.7 GHz, and the power is 1200 W; the steady magnetic field strength of the steady magnetic field treatment is 1 T.

[0041] The 1:6:0.9 of the extract, the solvent and the molecular sieve in step S3; the solvent in step S3 is an ethanol aqueous solution with a mass percentage concentration of 94%; the molecular sieve in step S3 is a mixture of MCM-48 molecular sieve, ZSM-8 molecular sieve and SSZ-13 molecular sieve mixed in a mass ratio of 1:2:1; the mass ratio of the waxberry crude product to the ethanol solution in step S4 is 1:6.

[0042] It is detected that the purity of the waxberry fruit extract prepared by the method is 99.83%, and the extraction rate is 97.0%, wherein the extraction rate = (the mass of the waxberry fruit extract in the crude extract × the purity) ÷ (the mass of the waxberry pomace powder × the percentage content of the waxberry fruit extract in the waxberry pomace powder) × 100%. Embodiment 3

[0043] A method for preparing high-purity waxberry fruit extract catalyzed by molecular sieve, comprising the following steps:

[0044] Step S1, raw material pretreatment: the waxberry pomace obtained after the fresh waxberry is juiced, dried to a constant weight at a temperature of 73℃, and then crushed to a certain mesh number to obtain waxberry pomace powder;

[0045] Step S2, multi-energy field assisted extraction: the waxberry pomace powder prepared in step S1 is added with an ethanol aqueous solution, and reflux extraction is performed for 5 times under the action of a multi-energy field; the filtrates are combined, and the ethanol aqueous solution is removed by rotary evaporation; then, after freeze-drying, an extract is obtained;

[0046] Step S3, molecular sieve catalysis: the extract is dissolved in a solvent to form a solution, then the molecular sieve is added to the solution, and after being uniformly dispersed, the solution is placed in a polytetrafluoroethylene-lined hydrothermal reaction kettle, and hydrothermal reaction is carried out at 130℃ for 5 h; after the reaction is completed, the hydrothermal reaction kettle is cooled to room temperature, and the reaction liquid is centrifuged; the supernatant is filtered, and the solvent is removed by rotary evaporation to obtain a waxberry fruit extract crude product;

[0047] Step S4, purification: the crude myricetin prepared in step S3 is dissolved in an ethanol solution with a mass percentage of 32%, and after filtration, the filtrate is adsorbed by an adsorption column (50*6 cm) filled with macroporous resin D101, then eluted with an ethanol solution with a mass percentage of 30%, and the eluate is discarded; then eluted with an ethanol solution with a mass percentage of 64%, and the eluate is collected, the ethanol solution is removed by rotary evaporation, and then dried at 56°C until the weight is constant to obtain myricetin.

[0048] The mesh number in step S1 is 50; the mass ratio of the waxberry pomace powder to the ethanol aqueous solution in step S2 is 1:10; the mass percentage of the ethanol aqueous solution in step S2 is 80%; the multi-energy field assisted action in step S2 includes ultrasonic treatment, microwave treatment and steady magnetic field treatment; the ultrasonic frequency of the ultrasonic treatment is 85 kHz, and the power is 800 W; the microwave frequency of the microwave treatment is 2.8 GHz, and the power is 1400 W; the steady magnetic field strength of the steady magnetic field treatment is 1.7 T.

[0049] The mass ratio of the extract, the solvent and the molecular sieve in step S3 is 1:6.5:1; the solvent in step S3 is an ethanol aqueous solution with a mass percentage of 95%; the molecular sieve in step S3 is a mixture of MCM-48 molecular sieve, ZSM-8 molecular sieve and SSZ-13 molecular sieve mixed in a mass ratio of 1:2:1; the mass ratio of the crude myricetin to the ethanol solution in step S4 is 1:6.5.

[0050] It is detected that the purity of the myricetin prepared by the method is 99.89%, and the extraction rate is 97.5%, wherein the extraction rate = (the mass of the crude myricetin × the purity) ÷ (the mass of the waxberry pomace powder × the percentage content of myricetin in the waxberry pomace powder) × 100%. Example 4

[0051] A method for preparing high-purity myricetin catalyzed by a molecular sieve, comprising the following steps:

[0052] Step S1, raw material pretreatment: the waxberry pomace obtained after the fresh waxberry is pitted and juiced is dried at a temperature of 78°C until the weight is constant, and then crushed to a certain mesh number to obtain waxberry pomace powder;

[0053] Step S2, multi-energy field assisted extraction: the waxberry pomace powder prepared in step S1 is added with an ethanol aqueous solution, and refluxed for extraction 6 times under the action of a multi-energy field, and then the filtrate is combined, the ethanol aqueous solution is removed by rotary evaporation, and then freeze-dried to obtain an extract;

[0054] Step S3, molecular sieve catalysis: the extract is dissolved in a solvent to form a solution, then the molecular sieve is added to the solution, and after uniform dispersion, it is placed in a polytetrafluoroethylene-lined hydrothermal reactor, and hydrothermal reaction is carried out at 140℃ for 5.5h. After the reaction is completed, the hydrothermal reactor is cooled to room temperature, and the reaction solution is centrifuged. After the supernatant is filtered and the solvent is removed by rotary evaporation, a crude myricetin product is obtained;

[0055] Step S4, purification: the crude myricetin product prepared in step S3 is dissolved in an ethanol solution with a mass percentage of 36%, and after filtration, the filtrate is adsorbed by an adsorption column (50x6cm) filled with macroporous resin D101, then eluted with an ethanol solution with a mass percentage of 35%, and the eluate is discarded. Then eluted with an ethanol solution with a mass percentage of 67%, and the eluate is collected, the ethanol solution is removed by rotary evaporation, and then dried at 58℃ until the weight is constant to obtain myricetin.

[0056] The mesh number in step S1 is 70; the mass ratio of the waxberry pomace powder to the ethanol aqueous solution in step S2 is 1:11; the mass percentage of the ethanol aqueous solution in step S2 is 85%; the multi-field assisted action in step S2 includes ultrasonic treatment, microwave treatment and steady magnetic field treatment; the ultrasonic frequency of the ultrasonic treatment is 95kHz, and the power is 950W; the microwave frequency of the microwave treatment is 2.9GHz, and the power is 1500W; the steady magnetic field strength of the steady magnetic field treatment is 2T.

[0057] The mass ratio of the extract, the solvent and the molecular sieve in step S3 is 1:7.5:1.1; the solvent in step S3 is an ethanol aqueous solution with a mass percentage of 95%; the molecular sieve in step S3 is a mixture of MCM-48 molecular sieve, ZSM-8 molecular sieve and SSZ-13 molecular sieve with a mass ratio of 1:2:1; the mass ratio of the crude myricetin product to the ethanol solution in step S4 is 1:7.5.

[0058] It is detected that the purity of the myricetin prepared by the method is 99.93%, and the extraction rate is 97.8%, wherein the extraction rate=(crude myricetin mass x purity)÷(waxberry pomace powder mass x percentage content of myricetin in waxberry pomace powder) x 100%. Example 5

[0059] A method for preparing high-purity myricetin by molecular sieve catalysis, comprising the following steps:

[0060] Step S1, raw material pretreatment: the waxberry pomace obtained after the fresh waxberry is pitted and juiced is dried at a temperature of 80℃ until the weight is constant, then crushed to a certain mesh number to obtain waxberry pomace powder;

[0061] Step S2, multi-energy field assisted extraction: the powder of waxberry pomace prepared in step S1 is added with ethanol aqueous solution, and then subjected to reflux extraction for 6 times under the assistance of multi-energy field; the filtrates are combined, and then subjected to rotary evaporation to remove the ethanol aqueous solution; and then subjected to freeze-drying to obtain the extract;

[0062] Step S3, molecular sieve catalysis: the extract is dissolved in a solvent to form a solution, and then the solution is added with molecular sieve and uniformly dispersed; and then the solution is placed in a polytetrafluoroethylene-lined hydrothermal reactor, and subjected to hydrothermal reaction at 150℃ for 6 hours; after the reaction is completed, the hydrothermal reactor is cooled to room temperature, and then the reaction solution is centrifuged; the supernatant is filtered, and then subjected to rotary evaporation to remove the solvent, to obtain the waxberry crude product;

[0063] Step S4, purification: the waxberry crude product prepared in step S3 is dissolved in an ethanol solution with a mass percentage of 38%, and then filtered; the filtrate is subjected to adsorption by an adsorption column (50×6 cm) filled with macroporous resin D101, and then subjected to elution by an ethanol solution with a mass percentage of 40%, and the eluate is discarded; and then subjected to elution by an ethanol solution with a mass percentage of 70%, and the eluate is collected; the ethanol solution is removed by rotary evaporation, and then dried at 60℃ until the weight is constant, to obtain the waxberry.

[0064] In step S1, the mesh number is 80; in step S2, the mass ratio of the powder of waxberry pomace to the ethanol aqueous solution is 1:12; in step S2, the mass percentage of the ethanol aqueous solution is 90%; the multi-energy field assistance in step S2 includes ultrasonic treatment, microwave treatment and steady magnetic field treatment; the ultrasonic frequency of the ultrasonic treatment is 100 kHz, and the power is 1000 W; the microwave frequency of the microwave treatment is 3.0 GHz, and the power is 1600 W; the steady magnetic field strength of the steady magnetic field treatment is 2.3 T; in step S3, the mass ratio of the extract to the solvent to the molecular sieve is 1:8:1.2.

[0065] In step S3, the solvent is an ethanol aqueous solution with a mass percentage of 96%; in step S3, the molecular sieve is a mixture of MCM-48 molecular sieve, ZSM-8 molecular sieve and SSZ-13 molecular sieve with a mass ratio of 1:2:1; in step S4, the mass ratio of the waxberry crude product to the ethanol solution is 1:8.

[0066] It is detected that the purity of the waxberry prepared by the method is 99.95%, and the extraction rate is 98.3%, wherein the extraction rate = (the mass of the waxberry in the crude extract × the purity) ÷ (the mass of the powder of waxberry pomace × the percentage content of waxberry in the powder of waxberry pomace) × 100%.

[0067] Comparative Example 1

[0068] A method for preparing high-purity waxberry by molecular sieve catalysis, which is basically the same as that of Example 1, except that there is no multi-energy field assistance in the extraction process.

[0069] The purity of the myricetin prepared by the method is 98.35%, and the extraction rate is 93.4%, wherein the extraction rate = (the mass of the crude myricetin × the purity) ÷ (the mass of the powder of the myricitrin pomace × the percentage of myricitrin in the powder of the myricitrin pomace) × 100%.

[0070] Comparative Example 2

[0071] A method for preparing high-purity myricetin by catalysis of a molecular sieve, which is basically the same as that in Example 1, except that the molecular sieve used is HZSM-5 molecular sieve.

[0072] The purity of the myricetin prepared by the method is 99.12%, and the extraction rate is 94.8%, wherein the extraction rate = (the mass of the crude myricetin × the purity) ÷ (the mass of the powder of the myricitrin pomace × the percentage of myricitrin in the powder of the myricitrin pomace) × 100%.

[0073] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A process for the catalytic preparation of high purity myricetin by using molecular sieves, characterized in that, It comprises the following steps: Step S1, raw material pretreatment: the red bayberry pomace obtained after the fresh red bayberry is pitted and juiced is dried to constant weight at a temperature of 65-80℃, then crushed to a certain mesh size to obtain red bayberry pomace powder; Step S2, multi-energy field assisted extraction: the red bayberry pomace powder prepared in step S1 is added with an ethanol aqueous solution, and reflux extraction is performed 3-6 times under the action of a multi-energy field, the filtrate is combined, the ethanol aqueous solution is removed by rotary evaporation, and then freeze-drying is performed to obtain an extract; the multi-energy field action comprises ultrasonic treatment, microwave treatment and steady magnetic field treatment; the ultrasonic treatment has an ultrasonic frequency of 70-100 kHz and a power of 600-1000 W; the microwave treatment has a microwave frequency of 2.5-3.0 GHz and a power of 1000-1600 W; the steady magnetic field treatment has a steady magnetic field strength of 0.3-2.3 T; Step S3, molecular sieve catalysis: the extract is dissolved in a solvent to form a solution, then molecular sieve is added to the solution, and after uniform dispersion, the solution is placed in a polytetrafluoroethylene-lined hydrothermal reaction kettle, and hydrothermal reaction is performed at 100-150℃ for 4-6 h; after the reaction is completed, the hydrothermal reaction kettle is cooled to room temperature, the reaction liquid is centrifuged, the supernatant is filtered, and the solvent is removed by rotary evaporation to obtain a crude morin product; the molecular sieve is a mixture of MCM-48 molecular sieve, ZSM-8 molecular sieve and SSZ-13 molecular sieve in a mass ratio of 1:2:1; Step S4, purification: the crude morin product prepared in step S3 is dissolved in an ethanol solution with a mass percentage concentration of 28-38%, filtered, and then the filtrate is adsorbed by an adsorption column 50×6 cm filled with macroporous resin D101, eluted with an ethanol solution with a mass percentage concentration of 20-40%, and the eluate is discarded; then eluted with an ethanol solution with a mass percentage concentration of 55-70%, the eluate is collected, the ethanol solution is removed by rotary evaporation, and then dried to constant weight at 52-60℃ to obtain morin.

2. The process for the catalytic preparation of high purity myricetin by using molecular sieves as claimed in claim 1, wherein, The certain mesh size in step S1 is 20-80 mesh.

3. The process for the catalytic preparation of high purity myricetin by using molecular sieves as claimed in claim 1, wherein, The mass ratio of the red bayberry pomace powder to the ethanol aqueous solution in step S2 is 1:(8-12).

4. The process for the catalytic preparation of high purity myricetin by using molecular sieves as claimed in claim 1, wherein, The mass percentage concentration of the ethanol aqueous solution in step S2 is 70-90%.

5. The process for the catalytic preparation of high purity myricetin by using molecular sieves as claimed in claim 1, wherein, The solvent in step S3 is an ethanol aqueous solution with a mass percentage concentration of 93-96%.

6. The process for the catalytic preparation of high purity myricetin by using molecular sieves as claimed in claim 1, wherein, The mass ratio of the crude morin product to the ethanol solution in step S4 is 1:(5-8).