阅读说明：本技术 一种乙基麦芽酚生产的绿色循环方法 (Green circulation method for producing ethyl maltol ) 是由 彭志强 李俊召 温细坤 覃伟华 于 2020-04-23 设计创作，主要内容包括：本发明请求保护一种乙基麦芽酚生产的绿色循环方法,其特征在于,首先将含碱式氯化镁固体废料中加水并搅拌均匀,之后减压蒸馏脱去有机溶剂,加酸,接着通过设置有活性炭的管式过滤器进一步脱色,然后滴加摩尔浓度为2.5～4mol/L的氢氧化钠溶液,待反应完全后,离心、干燥、粉碎分级,检验后包装。本发明工艺流程短,生产条件温和,即可充分利用麦芽酚生产中的废料,又可获得较高的经济回报,最终降低麦芽酚的生产成本,减少污染。有效的提升资源的利用效率,提升麦芽酚生产工艺的绿色性和可持续性。(The invention discloses a green circulating method for producing ethyl maltol, which is characterized by comprising the steps of adding water into solid waste containing basic magnesium chloride, uniformly stirring, carrying out reduced pressure distillation to remove an organic solvent, adding acid, further decoloring through a tubular filter provided with activated carbon, dropwise adding a sodium hydroxide solution with the molar concentration of 2.5-4 mol/L, after complete reaction, centrifuging, drying, crushing, grading, inspecting and packaging. The method has the advantages of short process flow and mild production conditions, can fully utilize waste materials in maltol production, can obtain higher economic return, and finally reduces the production cost of maltol and pollution. The utilization efficiency of resources is effectively improved, and the greenness and the sustainability of the maltol production process are improved.)

1. A green circulation method for producing ethyl maltol is characterized in that: the method comprises the following steps:

a: adding water into the solid waste containing the alkali magnesium chloride generated in the production of ethyl maltol, and uniformly stirring, wherein the weight ratio of the water to the solid waste containing the alkali magnesium chloride is 1.8-2: 1, so as to obtain a waste liquid containing the alkali magnesium chloride;

b: pumping the alkali-containing magnesium chloride waste liquid into a distillation still, carrying out reduced pressure distillation to obtain an organic solvent in the alkali-containing magnesium chloride waste liquid, and drying the organic solvent for recycling by an ethyl maltol production system;

c: adding a dilute hydrochloric acid solution into the basic magnesium chloride-containing waste liquid until the pH value of the solution is 4-6, wherein the mass fraction of the dilute hydrochloric acid solution is 13-15%;

d: c, enabling the solution obtained in the step c to pass through a filter, wherein the filter is a tubular filter, and activated carbon is arranged in the tubular filter;

e: transferring the solution obtained after filtering in the step d into a reaction kettle, dropwise adding a sodium hydroxide solution into the reaction kettle, slowly stirring, and reacting for 2 hours, wherein the adding amount of the sodium hydroxide solution is 1.05-1.15 times of the theoretical demand, and the molar concentration of the sodium hydroxide solution is 2.5-4 mol/L;

f: and e, transferring the solution obtained after the reaction in the step e into a centrifugal machine, washing the magnesium hydroxide filter cake obtained after the centrifugation to remove sodium chloride, drying the magnesium hydroxide filter cake at the temperature of 100-110 ℃, crushing and grading, and packaging after inspection.

2. The green recycling method of ethyl maltol as claimed in claim 1, wherein the dilute hydrochloric acid solution in step c is obtained from waste acid recovered from ethyl maltol production.

3. A green cycle method of ethyl maltol production according to claim 1 or 2, further comprising the step g: and f, carrying out rectification and impurity removal treatment on the washing waste liquid containing the sodium chloride obtained in the step f, and then electrolyzing to obtain a sodium hydroxide solution, wherein the sodium hydroxide solution is used in the step e.

4. The green cycle method for producing ethyl maltol as in any one of claims 1 to 3, wherein in the step e, a sodium hydroxide solution with a molar concentration of 4mol/L is added dropwise, and when the solution in the reaction kettle becomes turbid, a sodium hydroxide solution with a molar concentration of 2.5 to 3mol/L is added dropwise.

Technical Field

The invention relates to the technical field of maltol production, in particular to a green circulating method for producing ethyl maltol.

Background

Ethyl maltol, English name: ethyl maltol, chemical name: 2-ethyl-3-hydroxy-4H-pyrone (2-ethyl-3-hydroxy-4H-pyrone), molecular formula: C₇H₈0₃The powder is white needle-shaped or white crystal powder with aromatic fragrance, and is widely applied as a fragrance modifier and a flavoring agent. Is a food additive which is well recognized by people and has the advantages of safety, reliability, small dosage and obvious effect. The sweet potato flavor enhancer is a good flavor enhancer for tobacco, food, beverage, essence, fruit wine, daily cosmetics and the like, has a remarkable effect of improving and enhancing the flavor of food, plays a role of sweetening sweet food and can prolong the storage period of the food. In 1970, ethyl maltol has been formally listed in the food additive line by the world health organization and the food and agriculture organization of the united nations, and develops at a relatively fast speed at home and abroad by virtue of the characteristics of remarkable aroma enhancement effect, acknowledged safety, wide applicability and the like.

At present, more than ten mature processes for synthesizing ethyl maltol are available, and in terms of China, a total synthesis method, namely a furfural method, is mostly adopted. The process comprises the steps of firstly reacting furfural with a Grignard reagent to prepare ethyl furfuryl alcohol, and then carrying out a series of oxidation rearrangement on hexyl furfuryl alcohol to synthesize the ethyl maltol. The method for producing the ethyl maltol generates a large amount of magnesium-containing waste and salt-containing waste hydrochloric acid every day, and 2-3 tons of magnesium-containing waste residues are generated every ton of ethyl maltol products. Aiming at the problems that in the existing maltol production, the separation of products and solvents in the Grignard reaction, the addition reaction and the hydrolysis reaction and solid magnesium-containing waste is carried out by a vacuum filtration method, liquid-phase materials are mainly recycled by the method, the solid is treated as waste, and the solid waste causes great pollution to the environment, Chinese patent ZL2007100171626 discloses a method for recycling the waste in the maltol production, the method can fully utilize the maltol production waste, recover the solvents to the maximum extent, change the waste into useful products, and finally reduce the cost and the pollution. From the disclosure of the patent, the main improvement point of the patent lies in the separation process of the solvent and the solid waste, and the separated solid waste is simply subjected to pressure filtration, drying and high-temperature calcination to finally obtain the claimed solid magnesium oxide. And the high-temperature calcination method consumes a large amount of energy and is high in cost.

In recent years, magnesium hydroxide has been widely used as an important chemical product and intermediate in the fields of ceramic materials, environmental protection, medicines and the like. The magnesium hydroxide has the characteristics of high decomposition temperature, good thermal stability, no toxicity, no smoke, smoke suppression and the like, and can be used as a high-performance inorganic flame retardant to be applied to high polymer materials. In particular, the high-purity and superfine magnesium hydroxide flame retardant becomes a hot spot of development and research at home and abroad at present, and is rapidly developed in the field of inorganic flame retardants due to the characteristics of higher decomposition temperature, high thermal stability, no toxicity, no smoke, smoke suppression and the like. Dorsery and the like disclose a process for preparing magnesium hydroxide from magnesium-containing waste liquid in the production process of maltol, wherein the magnesium in the alkali-containing magnesium chloride waste liquid in the production process of maltol is recovered by an ammonia method after acidification and decoloration refining treatment, and a magnesium hydroxide product is produced, and the obtained product has controllable granularity and high purity. But the cost of the needed raw material ammonia water is high, and the method can only be used for producing high-purity reagent-grade, medical and electronic magnesium hydroxide.

Disclosure of Invention

Aiming at the problems of high energy consumption and low economy in the solid waste treatment in the conventional ethyl maltol production, the invention provides a method which is green, environment-friendly and low in energy consumption, can fully utilize waste materials in the maltol production, can obtain higher economic return, finally reduces the production cost of maltol and reduces pollution. The utilization efficiency of resources is effectively improved, and the greenness and the sustainability of the maltol production process are improved.

In order to achieve the above purpose, the invention provides the following technical scheme:

the technical scheme of the invention is as follows: a green circulation method for producing ethyl maltol is characterized in that: the method comprises the following steps:

a: adding water into the solid waste containing the alkali magnesium chloride generated in the production of ethyl maltol, and uniformly stirring, wherein the weight ratio of the water to the solid waste containing the alkali magnesium chloride is 1.8-2: 1, so as to obtain a waste liquid containing the alkali magnesium chloride;

b: pumping the alkali-containing magnesium chloride waste liquid into a distillation still, carrying out reduced pressure distillation to obtain an organic solvent in the alkali-containing magnesium chloride waste liquid, and drying the organic solvent for recycling by an ethyl maltol production system;

c: adding a dilute hydrochloric acid solution into the basic magnesium chloride-containing waste liquid until the pH value of the solution is 4-6, wherein the mass fraction of the dilute hydrochloric acid solution is 13-15%;

d: c, enabling the solution obtained in the step c to pass through a filter, wherein the filter is a tubular filter, and activated carbon is arranged in the tubular filter;

e: transferring the solution obtained after filtering in the step d into a reaction kettle, dropwise adding a sodium hydroxide solution into the reaction kettle, slowly stirring, and reacting for 2 hours, wherein the adding amount of the sodium hydroxide solution is 1.05-1.15 times of the theoretical demand, and the molar concentration of the sodium hydroxide solution is 2.5-4 mol/L;

f: and e, transferring the solution obtained after the reaction in the step e into a centrifugal machine, washing the magnesium hydroxide filter cake obtained after the centrifugation to remove sodium chloride, drying the magnesium hydroxide filter cake at the temperature of 100-110 ℃, crushing and grading, and packaging after inspection.

Further, the dilute hydrochloric acid solution in step c is from waste acid recovered from ethyl maltol production.

Further, the method also comprises the step g: and f, carrying out rectification and impurity removal treatment on the washing waste liquid containing the sodium chloride obtained in the step f, and then electrolyzing to obtain a sodium hydroxide solution, wherein the sodium hydroxide solution is used in the step e.

Further, in the step e, a sodium hydroxide solution with the molar concentration of 4mol/L is firstly dripped, and the sodium hydroxide solution with the molar concentration of 2.5-3 mol/L is dripped when the solution in the reaction kettle becomes turbid.

By firstly dropwise adding a high-concentration 4mol/L sodium hydroxide solution, crystallization nuclei are quickly formed in the solution, and then dropwise adding a 2.5-3 mol/L sodium hydroxide solution, the finally formed magnesium hydroxide crystals are large in particle size, good in filtering performance and high in magnesium recovery rate.

According to the green circulating method for producing ethyl maltol, disclosed by the invention, the final recovery rate of magnesium is more than 93%, and the product purity is more than 95%.

The invention has the advantages that:

(1) the method has the advantages that the solid waste containing the alkali magnesium chloride is used for preparing the magnesium hydroxide, the process flow is short, the production conditions are mild, the waste in the maltol production can be fully utilized, higher economic return can be obtained, the production cost of the maltol is finally reduced, and the pollution is reduced. The utilization efficiency of resources is effectively improved, and the greenness and the sustainability of the maltol production process are improved.

(2) Firstly, adding water into the solid waste containing basic magnesium chloride, uniformly stirring, then carrying out reduced pressure distillation to remove the organic solvent, and further decoloring through a tubular filter provided with activated carbon to ensure that the magnesium hydroxide product has better purity and whiteness.

(3) And electrolyzing the byproduct sodium chloride obtained in the recovery of the alkali-containing magnesium chloride solid waste to obtain a sodium hydroxide solution, so as to provide a raw material for preparing sodium hydroxide and further save the cost.

(4) And waste acid recovered in the production of ethyl maltol is used as a source of a dilute hydrochloric acid solution, so that chemical waste is fully utilized, waste is turned into wealth, and the cost for treating solid waste is further saved.

Detailed Description