Method for efficiently preparing maltol

Abstract

The invention provides a method for efficiently preparing maltol, and relates to the technical field of maltol preparation. After hydrolysis is completed, the hydrolyzed material is cooled to 40-45 DEG C to obtain a cooled material; sublimation mother liquor water is added to the cooled material, and a neutralizing agent is added to adjust pH for neutralization reaction to obtain a neutralized material, and the neutralized material is separated to obtain a crude maltol product; the crude maltol product is heated for sublimation, and the sublimated gas phase is cooled, crystallized, and centrifuged to obtain maltol, and the sublimation mother liquor water is reused in step S2; on the one hand, sodium bicarbonate powder is used as a neutralizing agent for neutralization, and the liquid of the neutralizing agent itself is small, so the neutralization mother liquor water is generated less, and the probability of bringing the product into the neutralization mother liquor water is reduced; on the other hand, the sodium bicarbonate powder is used as a neutralizing agent and the sublimation mother liquor water is reused in the neutralization reaction process, and the sublimation mother liquor water does not need to be extracted with chloroform, thereby reducing the raw material cost and not increasing the sewage treatment cost and difficulty.

Description

Technical Field

[0001] The invention belongs to the technical field of maltol preparation, and particularly relates to a method for efficiently preparing maltol. Background Art

[0002] The methods for producing maltol mainly include fermentation method, sugar alcohol method, furfural method and the like. The synthesis of maltol using furfural as raw material is the main method currently used in industry. The production process of maltol produced by the furfural method is divided into Grignard section, chlorination section, sublimation section, refining section and drying section. In the Grignard section, metal magnesium and methyl chloride are first reacted to prepare Grignard reagent, which is then reacted with furfural to obtain furfuryl ethanol. In the chlorination section, chlorination and hydrolysis reactions are carried out under the action of chlorine gas, and the structure is rearranged and then neutralized. Then, the maltol is crystallized under acidic conditions through the sublimation section, refining section and drying section, and then crude maltol is obtained through separation, and then purified to obtain pure maltol. However, the crude maltol obtained in the chlorination and hydrolysis section contains a large amount of tar-like asphalt by-products. The traditional crude crystallization method not only has poor separation effect, but also consumes a large amount of solvent. In addition, the whole process has large labor intensity, low efficiency, large pollution, low yield of target product and poor purification and separation effect.

[0003] In the prior art, for example, Chinese invention patent No. 201810038283.7 discloses a method for separating impurities from crude maltol, which mainly includes the following steps: a. filtering the hydrolyzed material and cooling it to 30°C-35°C; b. pumping the hydrolyzed liquid into an extraction mixer and simultaneously pumping chloroform into the extractor to fully mix the hydrolyzed liquid and chloroform; c. the mixed liquid enters a stratifier, the light phase after stratification enters a hydrolyzed liquid collecting tank, the lower heavy phase enters a chloroform collecting tank and is placed in a distillation kettle to distill and recover chloroform, and the distilled material is sent to a sublimation kettle for sublimation; d. pumping the light phase material in the hydrolysis collecting tank into a neutralization kettle, adjusting the pH to 2.5-3.5, and reducing the temperature to 35°C-45°C The material is placed in a crystallizer for frozen crystallization, and then centrifugally dried and sent to a sublimation kettle for sublimation. The prior art directly separates and processes the liquid phase, and the by-product separation is relatively thorough. The extraction process and the chloroform recovery process are in a closed device, which directly avoids the environmental impact during neutralization and discharge and coarse agglomerate disposal, improves the working environment, shortens the production process, reduces labor intensity and improves the safety of the production process; the coarse crystallized material has high purity, less waste asphalt in the sublimation process, and the maltol yield is significantly increased; however, due to the addition of chloroform during extraction, the raw material cost is increased, and chloroform is easily hydrolyzed to form monochloroformic acid and hydrochloric acid, which increases the acidity, resulting in complex sewage composition and increased sewage treatment costs. Summary of the invention

[0004] In view of this, the present invention provides a method for efficiently preparing maltol without increasing the cost of sewage treatment.

[0005] The technical solution adopted by the present invention to solve its technical problem is: A method for efficiently preparing maltol comprises the following steps: S1: After the hydrolysis is completed, the temperature of the hydrolyzed material is cooled to 35°C-45°C to obtain a cooled material; S2: adding sublimation mother liquor water to the cooled material, and adding a neutralizing agent to adjust the pH for a neutralization reaction to obtain a neutralized material, wherein the neutralizing agent is sodium bicarbonate powder to reduce the liquid in the neutralization process, reduce the generation of neutralization mother liquor water, and reduce the probability of bringing the product into the neutralization mother liquor water; S3: separating the neutralized material to obtain crude maltol; S4: The crude maltol is heated for sublimation, and the sublimated gas phase is cooled, crystallized, and centrifuged to obtain maltol. The sublimation mother liquor water is recycled to step S2 to dilute the concentration of the neutralizer, so that the neutralization reaction is more complete.

[0006] Preferably, in the step S2, the weight ratio of the sublimation mother liquor water to the cooling material is 0.5-2:2-5.

[0007] Preferably, in the step S2, the pH value is 2.5-3.0, Preferably, the step S3 is specifically as follows: if methyl maltol is prepared, the neutralized material is cooled and crystallized, and then the crystallized material is centrifuged and dried, and after drying, ethanol is added for washing, and drying is continued to obtain crude methyl maltol.

[0008] Preferably, the step S3 is as follows: if ethyl maltol is prepared, the neutralized material is allowed to stand and separate into layers, and the oil phase material is crude ethyl maltol.

[0009] Preferably, the maltol is prepared by a preparation system for efficiently preparing maltol, the preparation system for efficiently preparing maltol comprising: a neutralization unit and a sublimation unit, the neutralization unit comprising a hydrolysis kettle, a neutralization kettle and a separation section, a sodium bicarbonate powder inlet is arranged at the top of the neutralization kettle, the bottom outlet of the hydrolysis kettle is connected to the material inlet of the neutralization kettle, the bottom outlet of the neutralization kettle is connected to the inlet of the separation section, the outlet of the separation section is connected to the inlet of the sublimation unit, and the mother liquor outlet of the sublimation unit is connected to the liquid phase recycling inlet of the neutralization kettle.

[0010] Preferably, the sublimation unit comprises: a sublimation kettle, a first receiving kettle, a soft water storage tank, a second receiving kettle, and a maltol centrifuge, wherein a spraying portion is arranged on the top of the first receiving kettle, the inlet of the sublimation kettle is connected to the outlet of the separation portion, the outlet of the sublimation kettle is connected to the top inlet of the first receiving kettle, the inlet of the spraying portion on the top of the first receiving kettle is connected to the outlet of the soft water storage tank, the top outlet of the first receiving kettle is connected to the top inlet of the second receiving kettle, the bottom outlet of the first receiving kettle is connected to the maltol centrifuge, the liquid phase outlet of the maltol centrifuge is connected to the liquid phase recycling inlet of the neutralization kettle, and the outlet of the second receiving kettle is connected to the inlet of the maltol centrifuge.

[0011] Preferably, the flow rate of the soft water in the spraying part is 0.01m / s-0.5m / s, the flow rate is 200L / h-300L / h, and the temperature of the soft water in the soft water storage tank is 5°C-10°C.

[0012] Preferably, the air volume of the first receiving kettle and the second receiving kettle is -0.07Mpa~-0.09Mpa.

[0013] Preferably, the sublimation unit further comprises an external circulation pump, the inlet of the external circulation pump is connected to the bottom outlet of the second receiving kettle, and the outlet of the external circulation pump is connected to the outlet of the distillation pipeline connecting the first receiving kettle and the second receiving kettle.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The method for efficiently preparing maltol provided by the present invention comprises the following steps: S1: after hydrolysis is completed, cooling the hydrolyzed material to 35°C-45°C to obtain a cooled material; S2: adding sublimation mother liquor water to the cooled material, and adding a neutralizer to adjust the pH to perform a neutralization reaction to obtain a neutralized material; S3: separating the neutralized material to obtain a crude maltol product; the yield of the crude maltol product reaches more than 68%; S4: heating the crude maltol product for sublimation, cooling, crystallizing and centrifuging the sublimated gas phase to obtain maltol, the conversion rate of maltol reaches more than 95%, and the sublimation mother liquor water is added to the cooled material to perform a neutralization reaction to obtain a neutralized material; The liquid water is recycled to the S2 step; on the one hand, sodium bicarbonate powder is used as a neutralizing agent for neutralization, and the neutralizing agent itself has less liquid, so less neutralization mother liquor water is produced, reducing the probability of bringing the product into the neutralization mother liquor water; on the other hand, sodium bicarbonate powder is used as a neutralizing agent and the sublimation mother liquor water is recycled to the neutralization reaction process, thereby reducing the waste of the product, and the added sublimation mother liquor water dilutes the sodium bicarbonate, so that the pH of the neutralization reaction is moderate, the neutralization reaction is more complete, and the sublimation mother liquor water does not need to be extracted with chloroform, thereby reducing the cost of raw materials and not increasing the cost and difficulty of sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1Block diagram of the preparation system for efficiently preparing maltol.

[0016] Figure 2 The process flow chart of the preparation system for efficiently preparing methyl maltol.

[0017] Figure 3 The process flow chart of the preparation system for efficiently preparing ethyl maltol.

[0018] Figure 4 It is a front view of the spraying part.

[0019] Figure 5 It is a cross-sectional view of the spraying part.

[0020] In the figure: a preparation system 10 for efficiently preparing maltol, a neutralization unit 100, a hydrolysis kettle 110, a neutralization kettle 120, a third valve 121, a fourth valve 122, a sodium bicarbonate powder inlet 121, a separation unit 130, a crude product centrifuge 131, a sedimentation tank 132, a recycling pump 140, a sublimation unit 200, a sublimation kettle 210, a first receiving kettle 220, a spraying part 221, a rotating part 2211, a nozzle 22111, a bearing 22112, a connecting part 2212, a connecting pipe 22121, a spring 22122, a sealing ring 22123, an annular groove 22124, a brine jacket 222, a soft water storage tank 230, a first valve 231, a second valve 232, a second receiving kettle 240, a circulating water jacket 241, a maltol centrifuge 250, an external circulation pump 260, and a vacuum pump 270. DETAILED DESCRIPTION

[0021] The technical solutions and technical effects of the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the present invention.

[0022] Please see Figures 1 to 5 , a method for efficiently preparing maltol, comprising the following steps: S1: After the hydrolysis is completed, the temperature of the hydrolyzed material is cooled to 35°C-45°C to obtain a cooled material; S2: adding sublimation mother liquor water to the cooled material, and adding a neutralizing agent to adjust the pH for a neutralization reaction to obtain a neutralized material, wherein the neutralizing agent is sodium bicarbonate powder to reduce the liquid in the neutralization process, reduce the generation of neutralization mother liquor water, and reduce the probability of bringing the product into the neutralization mother liquor water; S3: separating the neutralized material to obtain crude maltol; S4: The crude maltol is heated for sublimation, and the sublimated gas phase is cooled, crystallized, and centrifuged to obtain maltol. The sublimation mother liquor water is recycled to step S2 to dilute the concentration of the neutralizer, so that the neutralization reaction is more complete.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The method for efficiently preparing maltol provided by the present invention comprises the following steps: S1: after hydrolysis is completed, cooling the hydrolyzed material to 35°C-45°C to obtain a cooled material; S2: adding sublimation mother liquor water to the cooled material, and adding a neutralizer to adjust the pH to perform a neutralization reaction to obtain a neutralized material; S3: separating the neutralized material to obtain a crude maltol product; the yield of the crude maltol product reaches more than 68%; S4: heating the crude maltol product for sublimation, cooling, crystallizing and centrifuging the sublimated gas phase to obtain maltol, the conversion rate of maltol reaches more than 95%, and the sublimation mother liquor water is added to the cooled material to perform a neutralization reaction to obtain a neutralized material; The liquid water is recycled to the S2 step; on the one hand, sodium bicarbonate powder is used as a neutralizing agent for neutralization, and the neutralizing agent itself has less liquid, so less neutralization mother liquor water is produced, reducing the probability of bringing the product into the neutralization mother liquor water; on the other hand, sodium bicarbonate powder is used as a neutralizing agent and the sublimation mother liquor water is recycled to the neutralization reaction process, thereby reducing the waste of the product, and the added sublimation mother liquor water dilutes the sodium bicarbonate, so that the pH of the neutralization reaction is moderate, the neutralization reaction is more complete, and the sublimation mother liquor water does not need to be extracted with chloroform, thereby reducing the cost of raw materials and not increasing the cost and difficulty of sewage treatment.

[0024] Specifically, the hydrolyzed material refers to the crude maltol obtained after the chlorination hydrolysis stage, and the crude maltol contains a large amount of tar-like asphalt by-products.

[0025] Specifically, the hydrolyzed material is the same as the hydrolyzed material in the Chinese invention with application number 201810038283.7.

[0026] Furthermore, in the step S2, the weight ratio of the sublimation mother liquor water to the cooling material is 0.5-2:2-5, so as to adjust the pH of the neutralization reaction, so that the concentration of the sodium bicarbonate powder is appropriate and the neutralization reaction is more complete.

[0027] Furthermore, in the step S2, the pH value is adjusted to 2.5-3.0.

[0028] Furthermore, the S3 step is specifically as follows: if methyl maltol is prepared, the neutralized material is cooled and crystallized, and then the crystallized material is centrifuged and dried, and after drying, ethanol is added for washing, and further drying is performed to obtain a crude methyl maltol product. The neutralization reaction is complete, and there is very little product in the generated neutralization mother liquor water, and chloroform is no longer needed for extraction, which reduces the cost of raw materials and does not increase the cost and difficulty of sewage treatment.

[0029] Furthermore, the step S3 is specifically as follows: if ethyl maltol is prepared, the neutralized material is allowed to stand and separate into layers, and the oil phase material is the crude ethyl maltol.

[0030] Furthermore, the maltol is prepared by a preparation system for efficiently preparing maltol, which comprises: a neutralization unit and a sublimation unit. The neutralization unit comprises a hydrolysis kettle, a neutralization kettle and a separation unit. A sodium bicarbonate powder inlet is arranged on the top of the neutralization kettle, a bottom outlet of the hydrolysis kettle is connected to a material inlet of the neutralization kettle, a bottom outlet of the neutralization kettle is connected to an inlet of the separation unit, an outlet of the separation unit is connected to an inlet of the sublimation unit, and a mother liquor outlet of the sublimation unit is connected to a liquid phase recycling inlet of the neutralization kettle.

[0031] Further, the sublimation unit includes: a sublimation kettle, a first receiving kettle, a soft water storage tank, a second receiving kettle, a maltol centrifuge, and a vacuum pump. A spraying portion is arranged on the top of the first receiving kettle, the inlet of the sublimation kettle is connected to the outlet of the separation portion, the outlet of the sublimation kettle is connected to the top inlet of the first receiving kettle, the inlet of the spraying portion on the top of the first receiving kettle is connected to the outlet of the soft water storage tank, the top outlet of the first receiving kettle is connected to the top inlet of the second receiving kettle, the bottom outlet of the first receiving kettle is connected to the maltol centrifuge, the liquid phase outlet of the maltol centrifuge is connected to the liquid phase recycling inlet of the neutralization kettle, the outlet of the second receiving kettle is connected to the inlet of the maltol centrifuge, and the vacuum pump is connected to the second receiving kettle to The first receiving kettle and the second receiving kettle are evacuated. During the sublimation process, the vacuum pump evacuates the first receiving kettle and the second receiving kettle, and the sublimated material in the sublimation kettle is pumped into the first receiving kettle. The spraying part continuously sprays soft water, and the contact area between the powdered material and the soft water is increased, and the contact probability is increased, so that the powdered material in the vacuum state is dissolved in the water as much as possible, and the probability of the powdered material being vacuumed into the distillation pipeline connected to the top outlet of the first receiving kettle and the top inlet of the second receiving kettle, the second receiving kettle and the vacuum pump is reduced, so as to prevent the pipeline and the vacuum pump from being blocked, reduce the frequency of maintenance, reduce the loss of products, and reduce the use of receiving kettle equipment, shorten the production process, improve work efficiency, and increase the conversion rate of the sublimation process from 82% to 87% to more than 95%.

[0032] Furthermore, a brine jacket is provided outside the first receiving kettle, into which brine of -5°C to -1°C is circulated, and soft water of 5°C to 10°C is contained in the soft water storage tank; a circulating water jacket is provided outside the second receiving kettle, into which cooling circulating water of ≤25°C is circulated, and soft water from the soft water storage tank is injected into the second receiving kettle; the temperature inside the first receiving kettle is controlled by the brine in the brine jacket, and then the soft water continuously sprayed by the spraying part uniformly adsorbs the powdered material extracted from the sublimation kettle, so that the powdered material is rapidly crystallized when cooled, and the temperature inside the second receiving kettle is higher than that of the first receiving kettle, and the temperature difference is utilized to crystallize the powdered material in the first receiving kettle as much as possible, thereby reducing the probability of the powdered material entering the second receiving kettle, and reducing the probability of the powdered material being vacuum-drawn into the distillation pipeline, the second receiving kettle and the vacuum pump connecting the top outlet of the first receiving kettle and the top inlet of the second receiving kettle, thereby preventing the pipeline and the vacuum pump from being blocked, reducing the frequency of maintenance, and reducing the loss of products.

[0033] Furthermore, a first valve is provided on the pipeline connecting the soft water storage tank and the inlet of the spraying part to control the flow rate of soft water, and a second valve is provided on the pipeline connecting the soft water storage tank and the soft water inlet of the second receiving kettle to inject soft water into the second receiving kettle.

[0034] Furthermore, the spraying part is a sprinkler head, and the inlet of the spraying part is connected to the outlet of the soft water storage tank.

[0035] Furthermore, the spraying part includes a rotating component and a connecting component, the rotating component includes a nozzle and a bearing, the connecting component includes a connecting pipe, a spring and a sealing ring, an inner wall of the connecting pipe is provided with an annular groove, the bearing is located in the connecting pipe, the spring is located in the annular groove, one end of the spring is connected to the annular groove, the other end of the spring is connected to the sealing ring through a mounting bracket and a screw, the sealing ring is located at the lower part of the bearing, the bottom end of the pipeline connecting the soft water storage tank and the inlet of the spraying part is located in the bearing, the pipeline connecting the soft water storage tank and the inlet of the spraying part is welded to the cover of the first receiving kettle, the nozzle can rotate relative to the pipeline connecting the soft water storage tank and the inlet of the spraying part, and the nozzle can rotate, so that the water atomization effect is better to increase the contact area between the water mist and the sublimated powder particles.

[0036] Furthermore, the sealing ring is made of rubber and can enter the annular groove.

[0037] Furthermore, the sublimation unit also includes an external circulation pump, the inlet of the external circulation pump is connected to the bottom outlet of the second receiving kettle, and the outlet of the external circulation pump is connected to the outlet of the distillation pipeline connecting the first receiving kettle and the second receiving kettle. By adding the external circulation pump, the soft water in the second receiving kettle is circulated to flush the outlet of the distillation pipeline connecting the first receiving kettle and the second receiving kettle, so as to prevent the product from clogging the pipeline and make the product material completely collected in the soft water in the second receiving kettle. In addition, by flushing the outlet of the distillation pipeline connecting the first receiving kettle and the second receiving kettle, the material drawn into the pipeline is directly brought into the second receiving kettle by the soft water, so as to prevent the material from being drawn into the vacuum pump and causing the vacuum pump to be blocked.

[0038] Furthermore, the neutralization unit includes a reuse pump, the inlet of the reuse pump is connected to the outlet of the maltol centrifuge, and the outlet of the reuse pump is connected to the reuse inlet of the neutralization kettle, so as to centrifuge the product material crystallized in the first receiving kettle and the second receiving kettle to obtain the product, and the mother liquor after centrifugation is transported to the neutralization kettle for recycling, thereby reducing product waste, and no extraction is required, and no new raw materials will be introduced, thereby reducing costs and reducing the difficulty and cost of sewage treatment.

[0039] Please see Figure 4 Furthermore, the separation part is a crude product centrifuge, the inlet of the crude product centrifuge is connected to the bottom outlet of the neutralization kettle, and the outlet of the crude product centrifuge is connected to the material inlet of the sublimation kettle. When preparing methyl maltol, the material is centrifuged and dried by the crude product centrifuge, and ethanol is added for washing after drying, and the drying is continued to obtain crude methyl maltol, which is then transported to the sublimation kettle for sublimation and purification.

[0040] Furthermore, the bottom outlet of the neutralization kettle is connected to the material inlet of the sublimation kettle, the separation part is a sedimentation tank, the bottom outlet of the neutralization kettle is connected to the inlet of the sedimentation tank, when preparing ethyl maltol, the neutralized material in the neutralization kettle is allowed to stand and stratify, the neutralized material is the oil phase, the water phase is transported to the sedimentation tank for precipitation, and the oil phase is transported to the sublimation kettle for sublimation and purification.

[0041] Furthermore, the material outlet of the sedimentation tank is also connected to the material inlet of the sublimation kettle. After a long period of accumulation, the material in the water phase is continuously recovered, the upper clear liquid of the sedimentation tank enters the sewage treatment system for sewage treatment, and the crystals at the bottom of the sedimentation tank are transported to the sublimation kettle for sublimation and purification to reduce waste.

[0042] Furthermore, a third valve is provided on the pipeline connecting the bottom outlet of the neutralization kettle and the material inlet of the sublimation kettle, and a fourth valve is provided on the pipeline connecting the bottom outlet of the neutralization kettle and the inlet of the precipitation tank.

[0043] Furthermore, the flow rate of the soft water in the spraying part is 0.01m / s-0.5m / s, the flow rate is 200L / h-300L / h, and the temperature of the soft water in the soft water storage tank is 5℃-10℃. Spraying is used instead of directly injecting soft water into the first receiving kettle for cooling, so that the material is cooled and the probability of being adsorbed, precipitated and crystallized is increased.

[0044] Furthermore, the vacuum degree of the first receiving kettle and the second receiving kettle is -0.07Mpa~-0.09Mpa.

[0045] For ease of understanding, the present invention is further illustrated by the following examples: Embodiment 1 Preparation of methyl maltol: Use as Figure 2 The preparation system for efficiently preparing maltol shown in FIG. 1 ; S1: After the hydrolysis is completed, the jacket circulating water inlet and outlet valves of the hydrolysis kettle are opened to cool the material to 40° C.-45° C. to obtain a cooled material; then, relying on the high head difference of the equipment, the cooled material automatically flows to the neutralization kettle; S2: adding sublimation mother liquor water to the neutralization kettle, the weight ratio of the cooling material to the sublimation mother liquor water is 3:1, and adding sodium bicarbonate powder to adjust the pH to 2.5-3.0, and performing a neutralization reaction to obtain a neutralized material; S3: Stirring the neutralized material and cooling it to ≤10°C, conveying the neutralized material to a crude product centrifuge for centrifugation, centrifugation and drying, adding 60% ethanol for washing, the amount of ethanol used is 1% of the neutralized material, and continuing centrifugation and drying to obtain crude methyl maltol; the yield of crude methyl maltol can be increased from the original 55% to 68%; S4: Then send the sublimation kettle to sublimate, heat the crude methyl maltol, and make the temperature of the sublimation kettle reach 164℃-220℃, the crude methyl maltol begins to boil, and under the effect of vacuum degree of -0.078Mpa~-0.08Mpa, bring the maltol vapor from the sublimation kettle into the first receiving kettle, open the inlet and outlet valves and the first valve of the brine jacket of the first receiving kettle, use -3℃ brine and 7℃ soft water to spray and cool down, control the soft water flow rate to 0.1m / s, flow rate to 250L / h, so that the vapor phase material is fully contacted with the 7℃ soft water, and evenly absorbed It is cooled and rapidly crystallized to the bottom of the first receiving kettle; a small part of the methyl maltol material is pumped into the second receiving kettle, the inlet and outlet valves of the circulating water jacket of the second receiving kettle are opened, and 300L~350L of soft water is injected into the second receiving kettle, and the external circulation pump is used for circulation to thoroughly absorb and precipitate the methyl maltol material pumped into the second receiving kettle. After the distillation is completed for 4 hours, the materials in the first receiving kettle and the second receiving kettle are transported to the maltol centrifuge for centrifugation to obtain methyl maltol; the conversion rate is increased from 82.1% to 95.6% during the sublimation process.

[0046] Embodiment 2 Preparation of ethyl maltol: Use as Figure 3 The preparation system for efficiently preparing maltol shown in FIG. 1 ; S1: After the hydrolysis is completed, the jacket circulating water inlet and outlet valves of the hydrolysis kettle are opened to cool the material to 40° C.-45° C. to obtain a cooled material; then, relying on the high head difference of the equipment, the cooled material automatically flows to the neutralization kettle; S2: adding sublimation mother liquor water to the neutralization kettle, the weight ratio of the cooling material to the sublimation mother liquor water is 3:1, and adding sodium bicarbonate powder to adjust the pH to 2.5-3.0, and performing a neutralization reaction to obtain a neutralized material; S3: The neutralized material is allowed to stand and separate into layers. The neutralized material is the oil phase. The water phase is transported to a sedimentation tank for precipitation. The oil phase is transported to a sublimation kettle for sublimation and purification. The oil phase is the crude ethyl maltol. The yield of the crude ethyl maltol can be increased from the original 54.5% to 68.7%; After a long period of accumulation, the materials in the water phase are continuously recovered, the supernatant in the sedimentation tank enters the sewage treatment system for sewage treatment, and the crystals at the bottom of the sedimentation tank are transported to the sublimation kettle for sublimation and purification to reduce waste. S4: Then the crude ethyl maltol product is sent to the sublimation kettle for sublimation, and the crude ethyl maltol product is heated until the kettle temperature of the sublimation kettle reaches 164°C-220°C and the crude ethyl maltol product begins to boil. Under the action of a vacuum degree of -0.078Mpa~-0.08Mpa, the maltol vapor in the sublimation kettle is brought into the first receiving kettle, and the inlet and outlet valves and the first valve of the brine jacket of the first receiving kettle are opened, and -3°C brine and 7°C soft water are used for spraying and cooling, and the soft water flow rate is controlled to be 0.1m / s and the flow rate is 250L / h, so that the vapor phase material is fully in contact with the 7°C soft Water is evenly adsorbed and rapidly crystallized to the bottom of the first receiving kettle when cooled; a small part of the ethyl maltol material is pumped into the second receiving kettle, the inlet and outlet valves of the circulating water jacket of the second receiving kettle are opened, and 300L~350L of soft water is injected into the second receiving kettle, and an external circulation pump is used for circulation to thoroughly absorb and precipitate the ethyl maltol material pumped into the second receiving kettle. After the distillation is completed for 4 hours, the materials in the first receiving kettle and the second receiving kettle are transported to the maltol centrifuge for centrifugation to obtain ethyl maltol; the conversion rate is increased from 82% to 95.8% during the sublimation process.

[0047] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for efficiently preparing maltol, characterized in that: The following steps are involved: S1: After the hydrolysis is completed, the temperature of the hydrolyzed material is cooled to 35°C-45°C to obtain a cooled material; S2: adding sublimation mother liquor water to the cooled material, and adding a neutralizing agent to adjust the pH for a neutralization reaction to obtain a neutralized material, wherein the neutralizing agent is sodium bicarbonate powder to reduce the liquid in the neutralization process, reduce the generation of neutralization mother liquor water, and reduce the probability of bringing the product into the neutralization mother liquor water; S3: separating the neutralized material to obtain crude maltol; S4: The crude maltol is heated for sublimation, and the sublimated gas phase is cooled, crystallized, and centrifuged to obtain maltol. The sublimation mother liquor water is recycled to step S2 to dilute the concentration of the neutralizer, so that the neutralization reaction is more complete.

2. The method for efficiently preparing maltol as claimed in claim 1, characterized in that: In the step S2, the weight ratio of the sublimation mother liquor water to the cooling material is 0.5-2:2-5.

3. The method for efficiently preparing maltol as claimed in claim 1, characterized in that: In the step S2, the pH value is adjusted to 2.5-3.

0.

4. The method for efficiently preparing maltol according to any one of claims 1 to 3, characterized in that: Specifically, if methyl maltol is to be prepared, the neutralized material is cooled and crystallized, and then the crystallized material is centrifuged and dried, and then washed with ethanol and dried again to obtain a crude methyl maltol product.

5. The method for efficiently preparing maltol according to any one of claims 1 to 3, characterized in that: Specifically, if ethyl maltol is to be prepared, the neutralized material is allowed to stand and separate into layers, and the oil phase material is the crude ethyl maltol.

6. The method for efficiently preparing maltol according to any one of claims 1 to 5, characterized in that: The invention is prepared by a preparation system for efficiently preparing maltol, which comprises: a neutralization unit and a sublimation unit. The neutralization unit comprises a hydrolysis kettle, a neutralization kettle and a separation unit. A sodium bicarbonate powder inlet is arranged on the top of the neutralization kettle, a bottom outlet of the hydrolysis kettle is connected to a material inlet of the neutralization kettle, a bottom outlet of the neutralization kettle is connected to an inlet of the separation unit, an outlet of the separation unit is connected to an inlet of the sublimation unit, and a mother liquor outlet of the sublimation unit is connected to a liquid phase recycling inlet of the neutralization kettle.

7. The method for efficiently preparing maltol according to claim 6, characterized in that: The sublimation unit includes: a sublimation kettle, a first receiving kettle, a soft water storage tank, a second receiving kettle, and a maltol centrifuge. A spraying part is arranged on the top of the first receiving kettle, the inlet of the sublimation kettle is connected to the outlet of the separation part, the outlet of the sublimation kettle is connected to the top inlet of the first receiving kettle, the inlet of the spraying part on the top of the first receiving kettle is connected to the outlet of the soft water storage tank, the top outlet of the first receiving kettle is connected to the top inlet of the second receiving kettle, the bottom outlet of the first receiving kettle is connected to the maltol centrifuge, the liquid phase outlet of the maltol centrifuge is connected to the liquid phase recycling inlet of the neutralization kettle, and the outlet of the second receiving kettle is connected to the inlet of the maltol centrifuge.

8. The method for efficiently preparing maltol according to claim 7, characterized in that: The flow rate of the soft water in the spraying part is 0.01m / s-0.5m / s, the flow rate is 200L / h-300L / h, and the temperature of the soft water in the soft water storage tank is 5℃-10℃.

9. The method for efficiently preparing maltol according to claim 7, characterized in that: The voidage of the first receiving kettle and the second receiving kettle is -0.07Mpa~-0.09Mpa.

10. The method for efficiently preparing maltol according to claim 7, characterized in that: The sublimation unit further comprises an external circulation pump, the inlet of the external circulation pump is connected to the bottom outlet of the second receiving kettle, and the outlet of the external circulation pump is connected to the outlet of the distillation pipeline connecting the first receiving kettle and the second receiving kettle.

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