Fatty acid decolorization method

Abstract

The invention belongs to the technical field of chemical engineering, and discloses a decolorizing method of fatty acid. According to the scheme, the chromaticity of a crude product is greatly reduced in advance through two-stage molecular distillation, light components are collected to serve as a primarily-treated product, the primary product is deeply decolorized through an adsorbent after molecular distillation, the chromaticity of fatty acid is greatly reduced, energy consumption is reduced, operation is easy, and the decolorization rate of the product is increased; compared with a molecular distillation step and a single adsorbent adsorption step, the dosage of the adsorbent can be saved, and the treatment cost is reduced; after the adsorption step, the adsorbent and the product are separated by a gas pressure separation method, the yield of the product is increased, no leakage is caused, the chromaticity of the treated final product can be as low as 15 Hazen, the decolorization rate can reach 99% or above, and the method for decolorization has extremely high economic benefits.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and in particular to a method for decolorizing fatty acids. Background Technology

[0002] Color is an important parameter for evaluating fatty acids. Excessive color is a common problem in fatty acid production. Taking oleic acid as an example, oleic acid is a monounsaturated fatty acid. Hydrogenation of oleic acid yields stearic acid and isostearic acid. Industrial oleic acid has a high color, resulting in stearic acid and isostearic acid with high color. This high color cannot meet market requirements for isostearic acid. Therefore, oleic acid needs to be decolorized to obtain a high-quality product with low color.

[0003] Chinese patent application 201711498722.4 discloses a method for decolorizing crude algae oil. The method involves contacting crude algae oil with activated carbon in ethanol at 60-75°C, filtering the mixture using filter paper, contacting the filtrate with activated carbon at 60-75°C, and then filtering again with filter paper to remove the ethanol. The ratio of crude algae oil to activated carbon used is 0.5:1. After decolorization, the color changes from dark brown to light yellow. However, this method uses a large amount of adsorbent, resulting in high cost and a low decolorization rate, only achieving a light yellow color.

[0004] Chinese Patent 201010542688.8 discloses a method for decolorizing fatty acids through physical refining of rice bran oil. The method involves adding an appropriate amount of decolorizing agent to a mixed fatty acid system and then re-distilling it under high temperature and high vacuum. The resulting fatty acid product has a light yellow color. The final temperature of the distillation step is controlled at 250~280℃ and the vacuum degree is controlled at 100~200Pa. The temperature and vacuum degree are relatively high, and the energy consumption is large.

[0005] In existing technologies, fatty acids are typically decolorized using adsorbents. However, this method requires large amounts of adsorbent, resulting in high costs, low throughput, and frequent adsorbent leakage. Therefore, there is an urgent need for a new decolorization method to address these technical problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the aforementioned technical problems and provide a method for decolorizing fatty acids that is simple to operate, has a high decolorization rate, low cost, and low energy consumption.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for decolorizing fatty acids, comprising the following steps: (1) The fatty acid raw materials are subjected to first molecular distillation and second molecular distillation in sequence to perform preliminary decolorization and obtain preliminary decolorized fatty acids; (2) The preliminarily decolorized fatty acids are mixed with the adsorbent for deep decolorization. After separating the adsorbent, a low-color fatty acid product is obtained.

[0008] Furthermore, in the decolorization method, the fatty acid raw material in step (1) includes at least one of oleic acid, palmitic acid, stearic acid, and isostearic acid.

[0009] Furthermore, in the decolorization method, step (1) of the first molecular distillation and the second molecular distillation includes the following steps: setting the preheating temperature, heating temperature, vacuum pressure, and condensation temperature of the molecular distillation apparatus; after the vacuum pressure and temperature reach the set conditions, adjusting the scraper speed, opening the feeding valve, controlling the feeding speed to feed, performing molecular distillation, and collecting the target product after molecular distillation at the light component outlet.

[0010] Furthermore, in the decolorization method, the conditions for the first molecular distillation in step (1) include: a preheating temperature of 40~100℃, a heating temperature of 60~140℃, a vacuum pressure of 1~500Pa, a condensation temperature of 0~20℃, a scraper rotation speed of 80~200rpm, and a feed rate of 2~30mL / min.

[0011] Furthermore, in the decolorization method, the conditions for the second molecular distillation in step (1) include: a preheating temperature of 100~150℃, a heating temperature of 120~180℃, a vacuum pressure of 1~500Pa, a condensation temperature of 0~10℃, a scraper rotation speed of 80~200rpm, and a feed rate of 2~30mL / min.

[0012] Furthermore, in the decolorization method, the adsorbent in step (2) includes one or more of activated carbon, 13X molecular sieve, Al2O3 spheres, kaolin, and silica gel.

[0013] Furthermore, in the decolorization method, the mass ratio of the adsorbent in step (2) to the fatty acid raw material in step (1) is 0.01~0.1:1.

[0014] Furthermore, in the decolorization method, the deep decolorization method in step (2) is: dynamic adsorption under water bath shaking.

[0015] Furthermore, in the decolorization method, the conditions for deep decolorization in step (2) include: an adsorption temperature of 20~80℃ and an adsorption time of 1~4h.

[0016] Furthermore, in the decolorization method, the method for separating the adsorbent in step (2) is: gas pressure filtration; the gas source pressure of the gas pressure filtration method is 0.01~1MPa.

[0017] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: The present invention involves pre-treating the crude product by two-stage molecular distillation to significantly reduce its color, collecting the light components as the pre-treated product, and then using an adsorbent after molecular distillation to deeply decolorize the initial product, significantly reducing the color of fatty acids, saving energy, simplifying the operation, and improving the decolorization rate of the product. Compared with molecular distillation and single adsorbent adsorption steps, it can save adsorbent usage and reduce processing costs. After the adsorption step, the adsorbent and product are separated by gas pressure separation, increasing the product yield and preventing filtration leakage. The final product after treatment can have a color as low as 15 Hazen and a decolorization rate of over 99%. This method of decolorization has extremely high economic benefits. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0019] Figure 1 This is a schematic diagram of the process route for the decolorization method of fatty acids. Detailed Implementation

[0020] This invention provides a method for decolorizing fatty acids, and the process flow diagram is shown below. Figure 1 As shown, it includes the following steps: (1) The fatty acid raw materials are subjected to first molecular distillation and second molecular distillation in sequence to perform preliminary decolorization and obtain preliminary decolorized fatty acids; (2) The preliminarily decolorized fatty acids are mixed with the adsorbent for deep decolorization. After separating the adsorbent, a low-color fatty acid product is obtained.

[0021] In this invention, the fatty acid raw material in step (1) includes at least one of oleic acid, palmitic acid, stearic acid, and isostearic acid.

[0022] In this invention, when the fatty acid raw materials in step (1) are selected from multiple sources, the proportion of each substance is not limited, and a scheme known to those skilled in the art can be used.

[0023] In this invention, the molecular distillation apparatus in step (1) is preferably the YHMD-60B model manufactured by Gongyi Yuhua Instrument Co., Ltd.

[0024] In this invention, the method of first molecular distillation and second molecular distillation in step (1) preferably includes the following steps: setting the preheating temperature, heating temperature, vacuum pressure and condensation temperature of the molecular distillation apparatus; after the vacuum pressure and temperature reach the set conditions, adjusting the scraper speed, opening the feeding valve, controlling the feeding speed to feed, performing molecular distillation, and collecting the target product after molecular distillation at the light component outlet.

[0025] In this invention, the conditions for the first molecular distillation in step (1) include: a preheating temperature preferably of 40-100°C, more preferably of 40-80°C, and more preferably of 80°C; a heating temperature preferably of 60-140°C, more preferably of 100-120°C, and more preferably of 110°C; a vacuum pressure preferably of 1-500 Pa, more preferably of 5-50 Pa, and more preferably of 5 Pa; a condensation temperature preferably of 0-20°C, more preferably of 5-15°C, and more preferably of 10°C; a scraper rotation speed preferably of 80-200 rpm, more preferably of 120-180 rpm, and more preferably of 150 rpm; and a feed rate preferably of 2-30 mL / min, more preferably of 5-20 mL / min, and more preferably of 5 mL / min.

[0026] In this invention, the conditions for the second molecular distillation in step (1) include: a preheating temperature preferably of 100-150°C, more preferably of 110-130°C, and more preferably of 120°C; a heating temperature preferably of 120-180°C, more preferably of 140-160°C, and more preferably of 160°C; a vacuum pressure preferably of 1-500 Pa, more preferably of 5-50 Pa, and more preferably of 5 Pa; a condensation temperature preferably of 0-10°C, more preferably of 5-10°C, and more preferably of 10°C; a scraper rotation speed preferably of 80-200 rpm, more preferably of 100-180 rpm, and more preferably of 150 rpm; and a feed rate preferably of 2-30 mL / min, more preferably of 5-10 mL / min, and more preferably of 5 mL / min.

[0027] In this invention, the adsorbent in step (2) preferably includes one or more of activated carbon, 13X molecular sieve, Al2O3 spheres, kaolin, and silica gel, more preferably includes one of activated carbon, 13X molecular sieve, Al2O3 spheres, and kaolin, and more preferably is activated carbon.

[0028] In this invention, the mass ratio of the adsorbent in step (2) to the fatty acid raw material in step (1) is preferably 0.01~0.1:1, more preferably 0.05~0.1:1, and even more preferably 0.1:1.

[0029] In this invention, the method for deep decolorization in step (2) is preferably: dynamic adsorption is carried out under the vibration of a water bath shaker.

[0030] In this invention, the conditions for deep decolorization in step (2) include: the adsorption temperature is preferably 20~80℃, more preferably 40~60℃, and even more preferably 50℃; the adsorption time is preferably 1~4h, more preferably 2~3h, and even more preferably 2h.

[0031] In this invention, the method for separating the adsorbent in step (2) is preferably: gas pressure filtration.

[0032] In this invention, the air source pressure of the pneumatic filtration method is preferably 0.01~1MPa, more preferably 0.2~0.5MPa, and even more preferably 0.4MPa.

[0033] In this invention, unless otherwise specified, other parameters and conditions are not limited, and solutions well known to those skilled in the art can be used.

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In this embodiment, colorimetry is analyzed using a UV spectrophotometer, colorimetric standard curves are established by preparing reagents with different colorimetric values, and colorimetric analysis is performed on the final product.

[0036] Example 1

[0037] This embodiment provides a method for decolorizing fatty acids, including the following steps: (1) The crude fatty acid raw material (dimerized by-product monomeric acid from Zhejiang plant) first undergoes a two-stage molecular distillation step. The molecular distillation apparatus is a YHMD-60B model manufactured by Gongyi Yuhua Instrument Co., Ltd. The feed is continuously fed by a peristaltic pump at a feed rate of 30 mL / min. The vacuum degree of the first-stage molecular distillation is controlled at 30 Pa, the preheating temperature is 40 °C, the heating temperature is 60 °C, the condensation temperature is 10 °C, and the scraper speed is 80 rpm. After the first-stage molecular distillation, the light components are collected and continue to enter the second-stage molecular distillation. The vacuum degree of the second-stage molecular distillation is 50 Pa, the preheating temperature is 100 °C, the heating temperature is 120 °C, the condensation temperature is 10 °C, the scraper speed is 100 rpm, and the feed rate is 5 mL / min. Finally, the light components are collected as pre-decolorized fatty acids. (2) The activated carbon powder (Henan Zhongju Purification Materials Co., Ltd., WP18200 wood charcoal, 200 mesh): raw material crude product was fed at a mass ratio of 0.01:1. Dynamic adsorption was carried out by shaking on a shaker at a temperature of 20℃ for 2 hours. After adsorption, the adsorbent was separated by gas pressure filtration at a gas source pressure of 0.01 MPa. The final product was a low-color fatty acid. The color of the final product was 208 Hazen, and the decolorization rate was 87.40%.

[0038] Example 2

[0039] This embodiment provides a method for decolorizing fatty acids. The difference from Example 1 is that the feed rate for the primary and secondary molecular distillations in step (1) is modified to 5 mL / min, the vacuum degree is modified to 5 Pa, and other parameters are the same as in Example 1. The final product has a color of 185 Hazen and a decolorization rate of 88.79%.

[0040] Example 3

[0041] This embodiment provides a method for decolorizing fatty acids. The difference from Example 1 is that in step (1), the primary molecular distillation is modified to a preheating temperature of 80°C, a heating temperature of 110°C, and a scraper rotation speed of 150 rpm; the secondary molecular distillation is modified to a preheating temperature of 120°C, a heating temperature of 160°C, and a scraper rotation speed of 150 rpm. Other parameters remain the same as in Example 1. The final product has a color of 135 Hazen, and the decolorization rate is 91.82%.

[0042] Example 4

[0043] (1) The crude fatty acid raw material (dimerized by-product monomeric acid from Zhejiang plant) first undergoes a two-stage molecular distillation step. The molecular distillation apparatus is a YHMD-60B model manufactured by Gongyi Yuhua Instrument Co., Ltd. The feed is continuously fed by a peristaltic pump at a feed rate of 5 mL / min. The vacuum degree of the first-stage molecular distillation is controlled at 5 Pa, the preheating temperature is 80℃, the heating temperature is 110℃, the condensation temperature is 10℃, and the scraper speed is 150 rpm. After the first-stage molecular distillation, the light components are collected and continue to enter the second-stage molecular distillation. The vacuum degree of the second-stage molecular distillation is 5 Pa, the preheating temperature is 120℃, the heating temperature is 160℃, the condensation temperature is 10℃, the scraper speed is 150 rpm, and the feed rate is 5 mL / min. Finally, the light components are collected as pre-decolorized fatty acids. (2) The activated carbon powder (Henan Zhongju Purification Materials Co., Ltd., WP18200 wood charcoal, 200 mesh): raw material crude product was fed at a mass ratio of 0.05:1. Dynamic adsorption was carried out by shaking on a shaker at a temperature of 50℃ for 2 hours. After adsorption, the adsorbent was separated by gas pressure filtration at a gas source pressure of 0.4 MPa. The final product was a low-color fatty acid. The color of the final product was 106 Hazen, and the decolorization rate was 93.57%.

[0044] Example 5

[0045] This embodiment provides a method for decolorizing fatty acids. The difference from Example 4 is that the mass ratio of adsorbent to crude raw material in step (2) is modified to 0.1:1, while other parameters and conditions remain the same as in Example 4. The final product has a color of 15 Hazen and a decolorization rate of 99.70%.

[0046] Example 6

[0047] This embodiment provides a method for decolorizing fatty acids. The difference from Example 4 is that in step (1), the vacuum degree is controlled at 50 Pa for both primary and secondary molecular distillation, while other parameters are the same as in Example 4. The final product has a color of 55 Hazen and a decolorization rate of 96.67%.

[0048] Example 7

[0049] This embodiment provides a method for decolorizing fatty acids. The difference from Example 4 is that the adsorption temperature in step (2) is 20°C, while other parameters are the same as in Example 4. The final product has a color of 109 Hazen and a decolorization rate of 93.40%.

[0050] The initial color of the raw materials, the color of the final product, and the decolorization rate of Examples 1-7 are shown in Table 1.

[0051] Table 1. Colorimetric test results for Examples 1-7

[0052] As can be seen from the table above, the method of the present invention can decolorize fatty acids with a product decolorization rate of up to 99% and a color intensity as low as 15 Hazen.

[0053] In summary, the fatty acid decolorization process proposed in this invention has the following beneficial effects: (1) Introducing molecular distillation decolorization before adsorption decolorization can process crude products in large quantities, allowing crude products with high color intensity to be decolorized significantly first, which can reduce the amount of adsorbent used in the subsequent process. The operation is simple and can process raw materials in large quantities, saving economic costs. (2) Gas pressure filtration can quickly separate the adsorbent from the product, and the separation is clean and leak-free, with high yield and saving time and cost; (3) The entire process requires no special techniques and is easy to industrialize; (4) The decolorization rate of the final product can reach more than 95%, and the color of the product is as low as 15 Hazen, which can reach the international advanced level.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for decolorizing fatty acids, characterized in that, Includes the following steps: (1) The fatty acid raw materials are subjected to first molecular distillation and second molecular distillation in sequence to perform preliminary decolorization and obtain preliminary decolorized fatty acids; (2) The preliminarily decolorized fatty acids are mixed with the adsorbent for deep decolorization. After separating the adsorbent, a low-color fatty acid product is obtained.

2. The decolorization method according to claim 1, characterized in that, The fatty acid raw materials in step (1) include at least one of oleic acid, palmitic acid, stearic acid, and isostearic acid.

3. The decolorization method according to claim 2, characterized in that, Step (1) The method of the first molecular distillation and the second molecular distillation includes the following steps: setting the preheating temperature, heating temperature, vacuum pressure and condensation temperature of the molecular distillation apparatus; after the vacuum pressure and temperature reach the set conditions, adjusting the scraper speed, opening the feeding valve, controlling the feeding speed to feed, performing molecular distillation, and collecting the target product after molecular distillation at the light component outlet.

4. The decolorization method according to any one of claims 1 to 3, characterized in that, Step (1) The conditions for the first molecular distillation include: preheating temperature of 40~100℃, heating temperature of 60~140℃, vacuum pressure of 1~500Pa, condensation temperature of 0~20℃, scraper rotation speed of 80~200rpm, and feed rate of 2~30mL / min.

5. The decolorization method according to claim 4, characterized in that, Step (1) The conditions for the second molecular distillation include: preheating temperature of 100~150℃, heating temperature of 120~180℃, vacuum pressure of 1~500Pa, condensation temperature of 0~10℃, scraper rotation speed of 80~200rpm, and feed rate of 2~30mL / min.

6. The decolorization method according to claim 1, characterized in that, The adsorbent in step (2) includes one or more of activated carbon, 13X molecular sieve, Al2O3 spheres, kaolin, and silica gel.

7. The decolorization method according to claim 1 or 6, characterized in that, The mass ratio of the adsorbent in step (2) to the fatty acid raw material in step (1) is 0.01~0.1:

1.

8. The decolorization method according to claim 7, characterized in that, The deep decolorization method described in step (2) is: dynamic adsorption under water bath shaking.

9. The decolorization method according to claim 8, characterized in that, The conditions for deep decolorization in step (2) include: an adsorption temperature of 20~80℃ and an adsorption time of 1~4h.

10. The decolorization method according to claim 1, characterized in that, The method for separating the adsorbent in step (2) is: pneumatic filtration; the gas source pressure of the pneumatic filtration method is 0.01~1MPa.

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