Process method for optimizing acesulfame potassium crystal habit

Abstract

The invention discloses a process for optimizing the crystal habit of an acesulfame potassium product. The process comprises the following steps: heating and dissolving an acesulfame crude product and a solvent to prepare a supersaturated solution, firstly, sequentially carrying out activated carbon adsorption and membrane adsorption for decoloration, then cooling at a certain rate for cooling crystallization, adding a certain amount of primary seed crystal in a nucleation stage 1, adding a certain amount of secondary seed crystal in a nucleation stage 2, and after the temperature of the material is reduced to 10 DEG C, cooling and crystallizing to obtain the acesulfame potassium crystal. And centrifugally drying the material to obtain the acesulfame potassium stable crystal form product. According to the present invention, the suitable solvent and the suitable cooling rate are selected, and the seed crystal is added during the cooling crystallization process, such that the content of the metastable crystal form is significantly reduced, the content of the stable crystal form is increased, and the particle size distribution, the yield and the purity of the acesulfame potassium product are effectively improved so as to solve the caking problem of the acesulfame potassium product during the storage process.

Description

Technical Field

[0001] The present invention belongs to the technical field of acesulfame production, and particularly relates to a process for optimizing the crystal habit of acesulfame products. Background Art

[0002] Acesulfame, also known as potassium acetylsulfonate, AK sugar, 6-methyl-1,2,3-oxathiazin-4-(3H)-one-2,2-dioxide potassium salt, English name: Acesulfame Potassium, Acesulfame K, 6-Methyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide potassium salt, molecular formula: C4H4KNO4S, molecular weight: 201.24, CAS number: 55589-62-3. It appears as a white crystalline powder, is highly soluble in water (270 g / L (20 °C)), slightly soluble in ethanol, and has a melting point of 229-232 °C. Due to the advantages of being safe and non-toxic, stable in nature, having a refreshing sweetness, no unpleasant aftertaste, and being reasonably priced, acesulfame is one of the most stable sweeteners in the world and is used in food, medicine, and other aspects.

[0003] Patent CN106496159B reported a production process for large-grained acesulfame crystals. In this invention, the cooling crystallization is divided into three stages. The produced acesulfame crystals are rod-shaped, with good uniformity. The acesulfame crystals with a particle size above 100 mesh reach more than 95%, improving the qualified rate and yield of the acesulfame crystal particle size; the fine crystals are reduced, shortening the separation time, improving the production efficiency, and increasing the product purity; the mother liquor adhered to the crystals is less, improving the crystal fluidity, facilitating transfer and drying, saving energy, and reducing production costs.

[0004] Patent application CN107459479A reported a method for producing round acesulfame crystals. In this invention, acesulfame is directly formulated to a certain concentration, and crystal seeds are added before the crystals precipitate. Crystallization is carried out with heat preservation and stirring at different temperatures to obtain round crystalline particles of acesulfame. The crystalline particles are of uniform size, the product does not cake after packaging, and it has good fluidity during use.

[0005] Patent application CN112574139A reported a crystallization method for fine-powdered acesulfame. In this invention, the particle size of acesulfame crystallization is reduced by adjusting the relevant operating parameters (concentration, temperature, rotation speed, etc.) of the original process. Among them, the proportion of particles with a size of 20-40 mesh decreases from 50-55% to 20-25%, and the proportion of particles with a size of 40-100 mesh increases from 45-50% to 75-80%, reducing the material for rework per batch and saving a large amount of costs.

[0006] Under specific crystallization conditions, only one crystal form of a compound is thermodynamically stable, and the others are metastable crystal forms. During solution crystallization, the metastable crystal form is transformed into the stable crystal form through solvent mediation. Acesulfame potassium exhibits polymorphism, and different crystal forms have different crystal habits. Its metastable crystal form has a flaky crystal habit and is easily broken, while the stable crystal form has a granular crystal habit. During the crystallization process, the crystal transformation behavior often results in a mixed crystal product, which greatly affects the particle size distribution, yield, and purity of the product, and ultimately leads to caking during the storage of acesulfame potassium products.

[0007] In the existing inventions, only the relevant parameters of the original process are adjusted to change the particle size of acesulfame potassium crystallization, and the influence of the crystal form of acesulfame potassium on the crystal habit of the product has not been deeply studied. Summary of the Invention

[0008] In view of the caking problem existing in the storage of acesulfame potassium products produced by the existing process, the present invention provides a process for optimizing the crystal habit of acesulfame potassium products. By optimizing the crystallization process of acesulfame potassium, the controllable preparation of stable crystal form products is realized, and the particle size distribution, yield, and purity of the products are improved, thereby effectively preventing the caking phenomenon during the storage of acesulfame potassium products.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows: The crude acesulfame potassium and the solvent are heated to dissolve and prepare a supersaturated solution. First, it is decolorized by activated carbon adsorption and membrane adsorption in sequence, and then cooled and crystallized at a certain rate. A certain amount of primary crystal seeds is added in nucleation stage 1, and a certain amount of secondary crystal seeds is added in nucleation stage 2. When the material temperature drops to 10 °C, the material is centrifuged and dried to obtain the stable crystal form product of acesulfame potassium.

[0010] According to a process for optimizing the crystal habit of acesulfame potassium products of the present invention, preferably, the solvent is an aqueous solution containing alcohol. Further, the alcohol is a lower alcohol, selected from one or more of methanol, ethanol, and propanol. Further, the alcohol concentration of the aqueous solution containing alcohol is 65 - 95%, such as 65%, 70%, 75%, 80%, 85%, 90%, or 95%. According to a process for optimizing the crystal habit of acesulfame potassium products of the present invention, preferably, the ratio of the crude acesulfame potassium to the solvent is 1:35 to 1:20, such as 1:35, 1:30, 1:25, or 1:20. According to a process for optimizing the crystal habit of acesulfame potassium products of the present invention, preferably, the temperature for heating and dissolving to prepare the supersaturated solution is 65 - 75 °C.

[0011] According to a process for optimizing the crystal habit of acesulfame potassium products of the present invention, preferably, the cooling rate for cooling crystallization is 5 - 10 °C / h.

[0012] A process for optimizing the crystal habit of acesulfame potassium products according to the present invention. Preferably, the temperature in the nucleation stage 1 is 62 - 64 °C, and / or the addition amount of the primary seed crystal is 0.1% - 0.3% of the weight of the crude product. Further, the primary seed crystal is the acesulfame potassium finished product. Further, the specific preparation method of the acesulfame potassium finished product is disclosed in Patent CN111377882B, such as its Example 1, Example 2, and Example 3. The entire content of CN111377882B is incorporated into this application.

[0013] A process for optimizing the crystal habit of acesulfame potassium products according to the present invention. Preferably, the temperature in the nucleation stage 2 is 57 - 59 °C, and / or the addition amount of the secondary seed crystal is 0.5% - 1.0% of the weight of the crude product. Further, the secondary seed crystal is the same as the primary seed crystal.

[0014] Advantageous effects of the present invention:

[0015] 1. By optimizing the crystallization process of acesulfame potassium, the present invention realizes the controllable preparation of the stable crystal form of acesulfame potassium, improves the particle size distribution, yield, and purity of acesulfame potassium products, and thus effectively solves the caking problem of acesulfame potassium finished products during storage.

[0016] 2. The process of the present invention is simple and easy to be applied industrially. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a process flow diagram of a process for optimizing the crystal habit of acesulfame potassium products according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Example 1:

[0019] A process method for optimizing the crystal habit of acesulfame potassium products, comprising the following steps: 18 g of acesulfame potassium crude product and 600 g of 95% methanol aqueous solution are heated to 65 °C to dissolve and prepare a supersaturated solution, which is decolorized by activated carbon adsorption and membrane adsorption in sequence, and then cooled and crystallized at a cooling rate of 5 °C / h. The primary seed crystal is added at 64 °C, and the addition amount of the seed crystal is 0.1% of the weight of the crude product. The secondary seed crystal is added at 59 °C, and the addition amount of the seed crystal is 0.5% of the weight of the crude product. When the material temperature drops to 10 °C, the material is centrifuged and dried to obtain the acesulfame potassium stable crystal form product. The particle size distribution of the product is shown in Table 1, the yield is 90.3%, and the purity is 99.4%.

[0020] Example 2:

[0021] A process method for optimizing the crystal habit of acesulfame potassium products, comprising the following steps: 25 g of acesulfame potassium crude product and 600 g of 95% ethanol aqueous solution were heated to 75 °C to dissolve and prepare a supersaturated solution, which was decolorized by activated carbon adsorption and membrane adsorption in sequence, and then cooled and crystallized at a cooling rate of 7 °C / h. The primary seed was added at 63 °C, and the addition amount of the seed was 0.2% of the weight of the crude product. The secondary seed was added at 58 °C, and the addition amount of the seed was 0.7% of the weight of the crude product. When the material temperature dropped to 10 °C, the material was centrifuged and dried to obtain a stable crystal form product of acesulfame potassium. The particle size distribution of the product is shown in Table 1, the yield was 89.8%, and the purity was 99.38%.

[0022] Example 3:

[0023] A process method for optimizing the crystal habit of acesulfame potassium product, comprising the following steps: 24 g of acesulfame potassium crude product and 600 g of 95% propanol aqueous solution were heated to 75 °C to prepare a supersaturated solution, which was decolorized by activated carbon adsorption and membrane adsorption in sequence, and then cooled and crystallized at a cooling rate of 9 °C / h. The primary seed was added at 62 °C, and the addition amount of the seed was 0.3% of the weight of the crude product. The secondary seed was added at 57 °C, and the addition amount of the seed was 1.0% of the weight of the crude product. When the material temperature dropped to 10 °C, the material was centrifuged and dried to obtain a stable crystal form product of acesulfame potassium. The particle size distribution of the product is shown in Table 1, the yield was 91%, and the purity was 99.35%.

[0024] Comparative Example 1:

[0025] 24 g of acesulfame potassium crude product and 600 g of 80% propanol aqueous solution were heated to 75 °C to dissolve and prepare a supersaturated solution, which was decolorized by activated carbon adsorption and membrane adsorption in sequence, and then cooled and crystallized at a cooling rate of 13 °C / h. The primary seed was added at 60 °C, and the addition amount of the seed was 0.05% of the weight of the crude product. The secondary seed was added at 55 °C, and the addition amount of the seed was 0.3% of the weight of the crude product. When the material temperature dropped to 10 °C, the material was centrifuged and dried to obtain a stable crystal form product of acesulfame potassium. The particle size distribution of the product is shown in Table 1, the yield was 82%, and the purity was 98.89%. Table 1 Particle size distribution of the product <30 mesh 30 - 50 mesh 50 - 80 mesh >80 mesh Example 1 8％ 42％ 47％ 3％ Example 2 4％ 47％ 45％ 4％ Example 3 5％ 41％ 48％ 6％ Comparative Example 1 0 15％ 52％ 33％

Claims

1. A process for optimizing the crystal habit of acesulfame potassium products, characterized in that, It includes the following steps: Heat the acesulfame potassium crude product and the solvent to dissolve and prepare a supersaturated solution. First, perform decolorization by activated carbon adsorption and membrane adsorption in sequence, and then cool and crystallize at a certain rate. Add a certain amount of primary crystal seeds in nucleation stage 1 and a certain amount of secondary crystal seeds in nucleation stage 2. When the material temperature drops to 10 °C, centrifuge and dry the material to obtain the acesulfame potassium stable crystal form product.

2. The process for optimizing the crystal habit of acesulfame potassium products according to claim 1, characterized in that, The solvent is an aqueous solution containing alcohol, and the alcohol is a lower alcohol, selected from one or more of methanol, ethanol, and propanol.

3. The process for optimizing the crystal habit of acesulfame potassium products according to claim 1, characterized in that, The cooling rate for cooling crystallization is 5 - 10 °C / h.

4. The process for optimizing the crystal habit of acesulfame potassium products according to claim 1, characterized in that, The temperature in nucleation stage 1 is 62 - 64 °C, and / or the addition amount of the primary crystal seeds is 0.1% - 0.3% of the weight of the crude product.

5. The process for optimizing the crystal habit of acesulfame potassium products according to claim 1, characterized in that, The temperature in nucleation stage 2 is 57 - 59 °C, and / or the addition amount of the secondary crystal seeds is 0.5% - 1.0% of the weight of the crude product.

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