Preparation method of sorbitol solution with low ethylene glycol content

Abstract

The invention belongs to the technical field of sugar alcohol preparation, and relates to a preparation method of a sorbitol solution with low ethylene glycol content, which comprises the following steps: carrying out hydrogenation treatment on glucose to obtain a sorbitol hydrogenated solution; the sorbitol hydrogenated liquid is sequentially subjected to an activated carbon decoloration treatment process, a positive and negative bed ion exchange treatment process, a mixed bed ion exchange treatment process, a plate and frame primary filtration treatment process, a refined filtration treatment process and a nanofiltration treatment process, and then is subjected to evaporation and concentration treatment to obtain the sorbitol liquid. The nanofiltration treatment is added between the refined filtration treatment and the evaporation concentration treatment, and then the technological parameters are controlled to remove part of ethylene glycol in the sorbitol hydrogenated liquid, so that the concentration of ethylene glycol in the sorbitol liquid product meets the specification requirement of being lower than 75 ppm. The method has the characteristics of being stable in process, easy to control, good in effect and the like, and broadens the sales market of sorbitol liquid products.

Description

Technical Field

[0001] The invention belongs to the technical field of sugar alcohol preparation, and particularly relates to a method for preparing a sorbitol liquid with a low ethylene glycol content. Background Art

[0002] Sorbitol is an important compound, widely present in the fruits of plants in nature, and can be used as food moisturizer, flavoring agent, antioxidant, cosmetic raw material, cigarette, toothpaste moisturizer, adhesive raw material and diuretic and choleretic drugs. The traditional methods for preparing sorbitol mainly include catalytic reduction, electrolytic oxidation and fermentation. The reduction method used for preparing sorbitol at home and abroad is mainly high-pressure catalytic hydrogenation. Although this method has many advantages, hydrogen is used in the reaction process. According to the test results of existing products, the content of ethylene glycol in sorbitol liquid is as high as 200ppm, even in crystallized sorbitol, the content of ethylene glycol is still as high as 182ppm. According to the prior art, methods such as chromatographic separation, activated carbon adsorption, crystallization, etc., cannot remove ethylene glycol in sorbitol liquid well. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing a sorbitol liquid with a low ethylene glycol content. In the production of the sorbitol liquid product, a nanofiltration treatment step is added, and then the purpose of reducing the ethylene glycol content is achieved by reasonable process parameter control.

[0004] The present invention is achieved by providing a method for preparing a sorbitol liquid with a low ethylene glycol content, the method comprising the following steps: glucose is hydrogenated to obtain a sorbitol hydrogenated liquid, the sorbitol hydrogenated liquid is sequentially subjected to an activated carbon decolorization treatment process, a cation bed ion exchange treatment process, a mixed bed ion exchange treatment process, a plate and frame primary filtration treatment process and a fine filtration treatment process, and then subjected to an evaporation and concentration treatment process to obtain the desired sorbitol liquid. After the sorbitol hydrogenated liquid is subjected to the fine filtration treatment process and before the evaporation and concentration treatment process, it is further subjected to a nanofiltration treatment process, the nanofiltration treatment process comprising the following steps: The sorbitol hydrogenated liquid after the fine filtration process is sequentially subjected to nanofiltration treatment of the first to fifth nanofiltration membrane groups, wherein the retained liquid after the nanofiltration treatment of the previous nanofiltration membrane group enters the next nanofiltration membrane group for nanofiltration treatment, and finally, the retained liquid after the nanofiltration treatment of the fifth nanofiltration membrane group is subjected to the evaporation concentration process; and, in the nanofiltration process, washing water is respectively introduced into the third nanofiltration membrane group, the fourth nanofiltration membrane group and the fifth nanofiltration membrane group through a booster pump to dilute the nanofiltration treated feed liquid, and the flow rate of washing water for each group is: 0.50~2.00m³ / h; wherein, The sorbitol hydrogenated liquid after the fine filtration treatment step has a refractive index of 35.0-45.0%, a sorbitol content of ≥93.0%, a temperature of 30.0-50.0°C, a pH of 3.50-8.00, and a conductivity of ≤20 μs / cm; The operating pressure during the nanofiltration treatment is 1.00-3.50 MPa, the feed flow rate is 10.00-30.00 m³ / h, and the concentration ratio of the nanofiltration treatment is 0.18-0.25.

[0005] Compared with the prior art, the method for preparing sorbitol liquid with low ethylene glycol content of the present invention improves the production process of sorbitol liquid, adds a nanofiltration process between the fine filtration process and the evaporation concentration process, and then controls the reasonable process parameters to remove part of the ethylene glycol components in the sorbitol hydrogenated liquid, thereby reducing the concentration of ethylene glycol in the sorbitol liquid product, so that the concentration of ethylene glycol in the sorbitol liquid product reaches the specification requirement of less than 75ppm. The method of the present invention has the characteristics of stable process, easy control, good effect, etc., and broadens the sales market of sorbitol liquid products. DETAILED DESCRIPTION

[0006] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0007] A preferred embodiment of the method for preparing a sorbitol liquid with a low ethylene glycol content of the present invention comprises the following steps: glucose is hydrogenated to obtain a sorbitol hydrogenated liquid, the sorbitol hydrogenated liquid is sequentially subjected to an activated carbon decolorization treatment process, a cation-cation bed ion exchange treatment process, a mixed bed ion exchange treatment process, a plate-frame primary filtration treatment process and a fine filtration treatment process, and then subjected to an evaporation concentration treatment process to obtain the desired sorbitol liquid, and the sorbitol hydrogenated liquid is further subjected to a nanofiltration treatment process after being subjected to the fine filtration treatment process and before being subjected to the evaporation concentration treatment process.

[0008] The nanofiltration treatment process includes the following steps: the sorbitol hydrogenated liquid treated by the fine filtration treatment process is sequentially subjected to nanofiltration treatment by the first to fifth nanofiltration membrane groups, wherein the retained liquid after the nanofiltration treatment by the previous nanofiltration membrane group enters the next nanofiltration membrane group for nanofiltration treatment, and finally, the retained liquid after the nanofiltration treatment by the fifth nanofiltration membrane group is subjected to the evaporation concentration treatment process. Moreover, during the nanofiltration treatment process, washing water is respectively introduced into the third nanofiltration membrane group, the fourth nanofiltration membrane group and the fifth nanofiltration membrane group through a booster pump to dilute the nanofiltration treated feed liquid, and the flow rate of washing water for each group is: 0.50~2.00m³ / h.

[0009] Inject washing water into the third nanofiltration membrane group, the fourth nanofiltration membrane group and the fifth nanofiltration membrane group to dilute the feed liquid, ensure normal feed, and ensure normal flow of each nanofiltration membrane group.

[0010] The sorbitol hydrogenated liquid after the fine filtration treatment step has a refractive index of 35.0-45.0%, a sorbitol content of ≥93.0%, a temperature of 30.0-50.0°C, a pH of 3.50-8.00, and a conductivity of ≤20μs / cm.

[0011] The operating pressure during the nanofiltration treatment is 1.00-3.50 MPa, the feed flow rate is 10.00-30.00 m³ / h, and the concentration ratio of the nanofiltration treatment is 0.18-0.25.

[0012] The present invention arranges five groups of nanofiltration membrane groups, so that the ethylene glycol component in the sorbitol hydrogenated liquid passes through the nanofiltration membrane into the transparent liquid of the nanofiltration membrane group, and the remaining retentate that does not pass through the nanofiltration membrane is further processed into sorbitol liquid, thereby preparing a sorbitol liquid product with a low ethylene glycol content.

[0013] The method for preparing the sorbitol solution with low ethylene glycol content of the present invention is further illustrated by specific examples below. Example 1

[0014] In the first embodiment of the method for preparing a sorbitol solution with a low ethylene glycol content of the present invention, the condition parameters that need to be controlled during the nanofiltration process are: The refractive index of the sorbitol hydrogenated liquid after the fine filtration treatment step is 45.0%, the sorbitol content is 94.00%, the temperature is 50.0°C, the pH is 8.00, and the conductivity is 20.0μs / cm; the operating pressure during the nanofiltration treatment is 3.50MPa, the feed flow rate is 10.0m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.18; the flow rate of each group of washing water is 0.50m³ / h.

[0015] In this embodiment, the ethylene glycol content in the sorbitol hydrogenated liquid before nanofiltration treatment is 180.22 ppm. The refractive index of the retentate after nanofiltration treatment is 41.8%, and the ethylene glycol content in the sorbitol liquid after evaporation concentration treatment is 60.37 ppm, which is lower than the specification requirement of 75 ppm, achieving the expected purpose. Example 2

[0016] In the second embodiment of the method for preparing a sorbitol solution with a low ethylene glycol content of the present invention, the parameters that need to be controlled during the nanofiltration process are: The refractive index of the sorbitol hydrogenated liquid after the fine filtration treatment step is 37.4%, the sorbitol content is 94.13%, the temperature is 45.6°C, the pH is 5.82, and the conductivity is 1.03μs / cm; the operating pressure during the nanofiltration treatment is 1.53MPa, the feed flow rate is 19.18m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.18; the flow rate of each group of washing water is 0.89m³ / h.

[0017] In this embodiment, the ethylene glycol content in the sorbitol hydrogenated liquid before nanofiltration treatment is 174.81 ppm. The refractive index of the retentate after nanofiltration treatment is 43.0%, and the ethylene glycol content in the sorbitol liquid after evaporation concentration treatment is 71.16 ppm, which is lower than the specification requirement of 75 ppm, achieving the expected purpose. Example 3

[0018] In the third embodiment of the method for preparing a sorbitol solution with a low ethylene glycol content of the present invention, the condition parameters that need to be controlled during the nanofiltration process are: The refractive index of the sorbitol hydrogenated liquid after the fine filtration treatment step is 38.3%, the sorbitol content is 94.73%, the temperature is 43.6°C, the pH is 5.62, and the conductivity is 3.91μs / cm; the operating pressure during the nanofiltration treatment is 1.70MPa, the feed flow rate is 19.53m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.20; the flow rate of each group of washing water is 0.89m³ / h.

[0019] In this embodiment, the ethylene glycol content in the sorbitol hydrogenated liquid before nanofiltration treatment is 182.12 ppm. The refractive index of the retentate after nanofiltration treatment is 44.5%, and the ethylene glycol content in the sorbitol liquid after evaporation concentration treatment is 64.45 ppm, which is lower than the specification requirement of 75 ppm, achieving the expected purpose. Example 4

[0020] In the fourth embodiment of the method for preparing a sorbitol solution with a low ethylene glycol content of the present invention, the condition parameters that need to be controlled during the nanofiltration process are: The refractive index of the sorbitol hydrogenated liquid after the fine filtration treatment step is 38.1%, the sorbitol content is 93.93%, the temperature is 44.1°C, the pH is 5.71, and the conductivity is 4.17μs / cm; the operating pressure during the nanofiltration treatment is 2.00MPa, the feed flow rate is 21.23m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.22; the flow rate of each group of washing water is 1.03m³ / h.

[0021] In this embodiment, the ethylene glycol content in the sorbitol hydrogenated liquid before nanofiltration treatment is 200.13 ppm. The refractive index of the retentate after nanofiltration treatment is 44.8%, and the ethylene glycol content in the sorbitol liquid after evaporation concentration treatment is 66.94 ppm, which is lower than the specification requirement of 75 ppm, achieving the expected purpose. Example 5

[0022] In the fifth embodiment of the method for preparing a sorbitol solution with a low ethylene glycol content of the present invention, the parameters that need to be controlled during the nanofiltration treatment are: The sorbitol hydrogenated liquid after the fine filtration treatment step has a refractive index of 35.0%, a sorbitol content of 93.0%, a temperature of 30.0°C, a pH of 3.50, and a conductivity of 1.03 μs / cm; the operating pressure during the nanofiltration treatment is 1.00 MPa, the feed flow rate is 30.00 m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.25; the flow rate of each group of washing water is 2.00 m³ / h.

[0023] In this embodiment, the ethylene glycol content in the sorbitol hydrogenated liquid before nanofiltration treatment is 160.55 ppm. The refractive index of the retentate after nanofiltration treatment is 46.2%, and the ethylene glycol content in the sorbitol liquid after evaporation concentration treatment is 71.17 ppm, which is lower than the specification requirement of 75 ppm, achieving the expected purpose.

[0024] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a sorbitol liquid with a low ethylene glycol content, the method comprising the following steps: hydrogenating glucose to obtain a sorbitol hydrogenated liquid, sequentially subjecting the sorbitol hydrogenated liquid to an activated carbon decolorization process, a cation bed ion exchange process, a mixed bed ion exchange process, a plate and frame primary filtration process and a fine filtration process, and then subjecting the sorbitol hydrogenated liquid to an evaporation and concentration process to obtain the desired sorbitol liquid, wherein: After the sorbitol hydrogenated liquid is treated by the fine filtration process and before the evaporation concentration process, it is further subjected to a nanofiltration process, wherein the nanofiltration process comprises the following steps: The sorbitol hydrogenated liquid after the fine filtration process is sequentially subjected to nanofiltration treatment of the first to fifth nanofiltration membrane groups, wherein the retained liquid after the nanofiltration treatment of the previous nanofiltration membrane group enters the next nanofiltration membrane group for nanofiltration treatment, and finally, the retained liquid after the nanofiltration treatment of the fifth nanofiltration membrane group is subjected to the evaporation concentration process; and, in the nanofiltration process, washing water is respectively introduced into the third nanofiltration membrane group, the fourth nanofiltration membrane group and the fifth nanofiltration membrane group through a booster pump to dilute the nanofiltration treated feed liquid, and the flow rate of washing water for each group is: 0.50~2.00m³ / h; wherein, The sorbitol hydrogenated liquid after the fine filtration treatment step has a refractive index of 35.0-45.0%, a sorbitol content of ≥93.0%, a temperature of 30.0-50.0°C, a pH of 3.50-8.00, and a conductivity of ≤20 μs / cm; The operating pressure during the nanofiltration treatment is 1.00-3.50 MPa, the feed flow rate is 10.00-30.00 m³ / h, and the concentration ratio of the nanofiltration treatment is 0.18-0.

25.

2. The method for preparing a sorbitol solution with a low ethylene glycol content according to claim 1, wherein: In the nanofiltration process, the condition parameters that need to be controlled are: The refractive index of the sorbitol hydrogenated liquid after the fine filtration treatment step is 45.0%, the sorbitol content is 94.00%, the temperature is 50.0°C, the pH is 8.00, and the conductivity is 20.0μs / cm; the operating pressure during the nanofiltration treatment is 3.50MPa, the feed flow rate is 10.0m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.18; the flow rate of each group of washing water is 0.50m³ / h.

3. The method for preparing a sorbitol solution with a low ethylene glycol content according to claim 1, wherein: In the nanofiltration process, the condition parameters that need to be controlled are: The refractive index of the sorbitol hydrogenated liquid after the fine filtration treatment step is 37.4%, the sorbitol content is 94.13%, the temperature is 45.6°C, the pH is 5.82, and the conductivity is 1.03μs / cm; the operating pressure during the nanofiltration treatment is 1.53MPa, the feed flow rate is 19.18m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.18; the flow rate of each group of washing water is 0.89m³ / h.

4. The method for preparing a sorbitol solution with a low ethylene glycol content according to claim 1, wherein: In the nanofiltration process, the condition parameters that need to be controlled are: The refractive index of the sorbitol hydrogenated liquid after the fine filtration treatment step is 38.3%, the sorbitol content is 94.73%, the temperature is 43.6°C, the pH is 5.62, and the conductivity is 3.91μs / cm; the operating pressure during the nanofiltration treatment is 1.70MPa, the feed flow rate is 19.53m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.20; the flow rate of each group of washing water is 0.89m³ / h.

5. The method for preparing a sorbitol solution with a low ethylene glycol content according to claim 1, wherein: In the nanofiltration process, the condition parameters that need to be controlled are: The refractive index of the sorbitol hydrogenated liquid after the fine filtration treatment step is 38.1%, the sorbitol content is 93.93%, the temperature is 44.1°C, the pH is 5.71, and the conductivity is 4.17μs / cm; the operating pressure during the nanofiltration treatment is 2.00MPa, the feed flow rate is 21.23m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.22; the flow rate of each group of washing water is 1.03m³ / h.

6. The method for preparing a sorbitol solution with a low ethylene glycol content according to claim 1, wherein: In the nanofiltration process, the condition parameters that need to be controlled are: The sorbitol hydrogenated liquid after the fine filtration treatment step has a refractive index of 35.0%, a sorbitol content of 93.0%, a temperature of 30.0°C, a pH of 3.50, and a conductivity of 1.03 μs / cm; the operating pressure during the nanofiltration treatment is 1.00 MPa, the feed flow rate is 30.00 m³ / h, and the concentration ratio of the nanofiltration treatment is controlled to be 0.25; the flow rate of each group of washing water is 2.00 m³ / h.