Polyol deodorization method

Abstract

The invention provides a deodorization method of polyol, and belongs to the technical field of separation and purification. The method comprises the following steps: firstly, carrying out steam activation on a composite adsorbent in an adsorption column, and then introducing polyhydric alcohol for adsorption; and after the adsorption is completed, purging the adsorption column with steam, and then sequentially carrying out primary cooling and secondary cooling on the adsorption column to complete the regeneration treatment of the composite adsorbent. The composite adsorbent in the adsorption column is activated and regenerated in a steam activation and steam purging mode, the service life of the composite adsorbent can be prolonged, compared with solvent regeneration, steam is easy to obtain and low in price, waste is few, the technological process of polyhydric alcohol deodorization is simple, and the cost is low. A relatively good separation effect can be achieved without introducing other solvents.

Description

Technical Field

[0001] The invention relates to the technical field of separation and purification, in particular to a deodorization method for polyols. Background Art

[0002] Polyols are a general term for alcohols containing two or more hydroxyl groups in the molecule, including but not limited to butanediol, caprylyl glycol, pentaerythritol, ethylene glycol, propylene glycol, xylitol, hexanediol, pentanediol, sorbitol and glycerol. Polyols play a significant role in coatings, dyes, paints, plastics and plastics industries, and are also widely used in pharmaceuticals, detergents, laundry detergents and cosmetics industries.

[0003] At present, some domestically produced industrial polyols have a distinct pungent odor. In order to make polyols more suitable for the cosmetic and pharmaceutical fields, it is necessary to produce odorless polyols. Such pungent odors are usually caused by trace impurities in industrial polyols, which are difficult to separate and remove due to their small content.

[0004] Patent CN110914228A discloses a method for decolorizing and deodorizing polyols, but the process is relatively complicated, including distillation and activated carbon adsorption treatment, and other substances such as water and neutralizers are introduced. Therefore, it is of great significance to study a method for deodorizing polyols. Summary of the invention

[0005] The object of the present invention is to provide a method for deodorizing polyols to solve the problem that the pungent odor in polyols cannot be removed in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for deodorizing a polyol, comprising the following steps:

[0008] (1) Activating the composite adsorbent in the adsorption column by steam, and then introducing polyol for adsorption;

[0009] (2) After the adsorption is completed, the adsorption column is purged with steam, and then the adsorption column is cooled for the first time and the second time in sequence to complete the regeneration process of the composite adsorbent.

[0010] Preferably, in step (1), the composite adsorbent comprises one or more of activated carbon, resin, clay, molecular sieve and alumina.

[0011] Preferably, in step (1), the flow rate of steam activation is 2 to 8 BV / h, the temperature of steam activation is 100 to 250° C., and the time of steam activation is 1 to 3 hours.

[0012] Preferably, in the step (1), the polyol is introduced into the adsorption column in a bottom-in-top-out manner for adsorption; the flow rate of the polyol is 0.5-3 BV / h, the temperature is 20-30° C.; and the adsorption time is 5-15 h.

[0013] Preferably, in step (2), steam is blown from top to bottom to purge the adsorption column; the temperature of the steam is 100-300° C., the flow rate of the steam blowing the adsorption column is 2-6 BV / h, and the steam is blown until no polyol is detected in the condensed water.

[0014] Preferably, in step (2), the first cooling is performed by using a clean water spray device, and the temperature of the adsorption column after the first cooling is 50-80°C.

[0015] Preferably, in step (2), gas is introduced for cooling during the second cooling, wherein the gas is nitrogen or compressed air.

[0016] Preferably, in step (2), the second cooling time is 0.5 to 1.5 hours.

[0017] Beneficial effects of the present invention:

[0018] (1) The present invention compounds several adsorbents including activated carbon, resin, clay, molecular sieve and alumina to obtain a composite adsorbent for deodorizing polyols. The composite adsorbent has a stable structure and high mechanical strength, and can separate trace odorous impurities in polyols, thereby achieving a deodorizing effect on polyols.

[0019] (2) The present invention uses steam activation and steam purging to activate and regenerate the composite adsorbent in the adsorption column, which can extend the service life of the composite adsorbent. Compared with solvent regeneration, steam is easy to obtain, cheap and produces less waste. The process flow of polyol deodorization is simple, and a better separation effect can be achieved without introducing other solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The graph is a curve showing the content changes of various impurities during the adsorption process of 97% octyl glycol in Example 1;

[0021] Figure 2 This is a curve chart showing the change in trace impurity content during steam purging of the adsorption column in Example 1. DETAILED DESCRIPTION

[0022] The present invention provides a method for deodorizing a polyol, comprising the following steps:

[0023] (1) Activating the composite adsorbent in the adsorption column by steam, and then introducing polyol for adsorption;

[0024] (2) After the adsorption is completed, the adsorption column is purged with steam, and then the adsorption column is cooled for the first time and the second time in sequence to complete the regeneration process of the composite adsorbent.

[0025] In the present invention, in step (1), the composite adsorbent comprises one or more of activated carbon, resin, clay, molecular sieve and alumina, preferably a composite adsorbent of resin and molecular sieve, and the mass ratio of resin to molecular sieve is 1 to 5:1, preferably 1 to 3:1.

[0026] In the present invention, in the step (1), the flow rate of steam activation is 2 to 8 BV / h, preferably 3 to 6 BV / h, and more preferably 4 to 5 BV / h; the temperature of steam activation is 100 to 250°C, preferably 110 to 200°C, and more preferably 120 to 150°C; the time of steam activation is 1 to 3 hours, preferably 1 to 2.5 hours, and more preferably 1 to 2 hours.

[0027] In the present invention, in the step (1), the polyol is introduced into the adsorption column in a bottom-in and top-out manner for adsorption; the flow rate of the polyol is 0.5-3 BV / h, preferably 1-2 BV / h; the temperature is 20-30°C, preferably 22-28°C; the adsorption time is 5-15h, preferably 8-13h, and more preferably 10-13h.

[0028] In the present invention, if the flow rate of the polyol is too fast, it may lead to insufficient adsorption of the polyol, and if the flow rate is too slow, the preparation time of the industrial process will be prolonged.

[0029] In the present invention, the polyol is introduced into the adsorption column in a bottom-in-top-out manner for adsorption, the solution is pumped into the adsorption column, the liquid level gradually rises, the solution and the adsorbent can be better in contact, and the tower effect of the adsorption column is fully exerted. If the top-in-bottom-out manner is adopted, the polyol is directly dripped onto the surface of the composite adsorbent due to gravity, pits may appear on the surface of the adsorbent, resulting in an uneven surface of the adsorbent, and the solution cannot be well diffused to the surrounding adsorbent surface.

[0030] In the present invention, in the step (2), steam is blown from top to bottom to purge the adsorption column; the temperature of the steam is 100-300°C, preferably 110-200°C, and more preferably 120-150°C; the flow rate of the steam blowing the adsorption column is 2-6BV / h, preferably 3-5BV / h, and more preferably 4BV / h; the steam is blown until no polyols are detected in the condensed water.

[0031] In the present invention, in the step (2), the first cooling is performed by using a clean water spray device, and the temperature of the adsorption column after the first cooling is 50 to 80°C, preferably 50 to 70°C.

[0032] In the present invention, in the step (2), gas is introduced to cool the temperature during the second cooling, wherein the gas is nitrogen or compressed air.

[0033] In the present invention, the adsorption column has recovered its usability after cooling down using a clean water spray device, but the clean water spraying causes moisture to exist in the adsorption column. Then nitrogen or compressed air is used for a second cooling, which can not only reduce the temperature of the adsorption column to room temperature but also dry the adsorption column at the same time. The adsorption column can only be used for the next cycle after its temperature is reduced to room temperature.

[0034] In the present invention, the first cooling and the second cooling are both performed from top to bottom.

[0035] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] The macroporous resin used in the embodiment of the present invention is Tianjin Yunkai D4020 macroporous adsorption resin, the molecular sieve is Luoyang Tianping X-type molecular sieve, and the adsorption column size is 300 ml.

[0037] Example 1

[0038] The macroporous resin and molecular sieve are mixed in a mass ratio of 1:1 to obtain a composite adsorbent, which is then loaded into an adsorption column. Pure water is added while filling to allow the composite adsorbent to settle naturally, keeping the adsorption column tight and free of bubbles. After filling, superheated steam at 150°C is passed at a flow rate of 3BV / h to activate the composite adsorbent for 1.5 hours.

[0039] After activation is completed, 97% octyl glycol (at room temperature) is pumped into the adsorption column from bottom to top at a flow rate of 1BV / h for adsorption. After 13 hours of adsorption, 150°C steam is passed from top to bottom at a flow rate of 3BV / h to purge the adsorption column. After about 2.5 hours, no octyl glycol is detected in the condensed water in the adsorption column. Then the clean water spray device is turned on to cool the adsorption column for the first time. After about 0.5 hours, the temperature of the adsorption column drops to 50°C. Then compressed air is passed from top to bottom to cool the adsorption column for the second time. The second cooling time is 0.5 hours, completing the regeneration of the composite adsorbent.

[0040] Example 2

[0041] The macroporous resin and molecular sieve are mixed in a mass ratio of 2:1 to obtain a composite adsorbent, which is then loaded into an adsorption column. Pure water is added while filling to allow the composite adsorbent to settle naturally, keeping the adsorption column tight and free of bubbles. After filling, superheated steam at 120°C is passed at a flow rate of 4BV / h to activate the composite adsorbent for 2 hours.

[0042] After activation, 99% 2,3-butanediol (room temperature) was pumped into the adsorption column from bottom to top at a flow rate of 1.5BV / h for adsorption. After 10 hours of adsorption, 120°C steam was passed from top to bottom at a flow rate of 4BV / h to purge the adsorption column. After about 2.5 hours, no 2,3-butanediol was detected in the condensed water in the adsorption column. Then, the clean water spray device was turned on to cool the adsorption column for the first time. After about 0.5 hours, the temperature of the adsorption column dropped to 50°C. Then, compressed air was passed from top to bottom to cool the adsorption column for the second time. The second cooling time was 0.5 hours, completing the regeneration of the composite adsorbent.

[0043] Comparative Example 1

[0044] Put the macroporous resin into the adsorption column, add pure water while filling, let the resin settle naturally, keep the adsorption column tight and free of bubbles. After filling, pass 150℃ superheated steam at a flow rate of 3BV / h to activate the resin. The activation time is 1h.

[0045] After activation is completed, 97% octyl glycol (at room temperature) is pumped into the adsorption column from bottom to top at a flow rate of 1BV / h for adsorption. After 8 hours of adsorption, 150°C steam is passed at a flow rate of 3BV / h to purge the adsorption column. After about 2.5 hours, no octyl glycol is detected in the condensed water in the adsorption column. Then, the clean water spray device is turned on to cool the adsorption column for the first time. After about 0.5 hours, the temperature of the adsorption column drops to 50°C. Then, compressed air is passed from top to bottom to cool the adsorption column for the second time. The second cooling time is 0.5 hours, and the resin regeneration process is completed.

[0046] Comparative Example 2

[0047] The macroporous resin and molecular sieve are mixed in a mass ratio of 2:1 to obtain a composite adsorbent, which is then loaded into an adsorption column. Pure water is added while filling to allow the composite adsorbent to settle naturally, keeping the adsorption column tight and free of bubbles. After filling, the composite adsorbent is activated by soaking in anhydrous ethanol for 2 hours.

[0048] After activation, 99% 2,3-butanediol (at room temperature) was pumped into the adsorption column from bottom to top at a flow rate of 1.5 BV / h for adsorption. After 10 hours of adsorption, the resin regeneration step was entered. Anhydrous ethanol was pumped into the adsorption column, and it was repeatedly cleaned with anhydrous ethanol. After about 1 hour, it was detected that there was no 2.3-butanediol. Then, anhydrous ethanol was added to soak for 120 hours. The composite adsorbent was regenerated and could be put into the next cycle.

[0049] The polyol content in Examples 1 to 2 and Comparative Examples 1 to 2, the adsorption capacity of the adsorption column, and the repeated utilization cycle were measured. The results are shown in Table 1:

[0050] Table 1 Test results of Examples 1 to 2 and Comparative Examples 1 to 2

[0051]

[0052] Figure 1 The content of trace impurities detected by gas chromatography during the adsorption process in Example 1 shows the changes in the content of 9 impurities detected in octyl glycol. After comparison with artificial smell, it was found that impurities 4, 5 and 1 were impurities with pungent odors, so octyl glycol had a pungent odor after 13 hours. The adsorption capacity of the composite adsorbent for octyl glycol can reach 13BV. Figure 2 The change of trace impurity content during steam regeneration detected by gas chromatography in Example 1, a total of 4 impurities were detected. After 140 minutes of regeneration, the content of all impurities was 0, and then the adsorption column was cooled down and put into use in the next cycle.

[0053] As can be seen from the above embodiments, the present invention provides a method for deodorizing polyols, firstly steam-activating the composite adsorbent in the adsorption column, and then introducing the polyols for adsorption; after the adsorption is completed, the adsorption column is purged with steam, and then the adsorption column is sequentially cooled for the first time and the second time to complete the regeneration of the composite adsorbent. The present invention uses steam activation and steam purging to activate and regenerate the composite adsorbent in the adsorption column, which can extend the service life of the composite adsorbent. Compared with solvent regeneration, steam is easy to obtain, cheap and less waste. The process flow of polyol deodorization is simple, and a better separation effect can be achieved without introducing other solvents.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for deodorizing a polyol, characterized in that: The steps include: (1) Activating the composite adsorbent in the adsorption column by steam, and then introducing polyol for adsorption; (2) After the adsorption is completed, the adsorption column is purged with steam, and then the adsorption column is cooled for the first time and the second time in sequence to complete the regeneration process of the composite adsorbent.

2. The method for deodorizing a polyol according to claim 1, characterized in that: In the step (1), the composite adsorbent comprises one or more of activated carbon, resin, clay, molecular sieve and alumina.

3. The method for deodorizing a polyol according to claim 2, characterized in that: In the step (1), the flow rate of steam activation is 2 to 8 BV / h, the temperature of steam activation is 100 to 250° C., and the time of steam activation is 1 to 3 hours.

4. The method for deodorizing a polyol according to any one of claims 1 to 3, characterized in that: In the step (1), the polyol is introduced into the adsorption column in a bottom-in and top-out manner for adsorption; the flow rate of the polyol is 0.5 to 3 BV / h, and the temperature is 20 to 30° C.; and the adsorption time is 5 to 15 hours.

5. The method for deodorizing a polyol according to claim 4, characterized in that: In the step (2), steam is blown from top to bottom to purge the adsorption column; the temperature of the steam is 100 to 300° C., the flow rate of the steam blowing the adsorption column is 2 to 6 BV / h, and the steam is blown until no polyol is detected in the condensed water.

6. The method for deodorizing a polyol according to claim 3 or 5, characterized in that: In the step (2), the first cooling is performed by using a clean water spray device, and the temperature of the adsorption column after the first cooling is 50 to 80°C.

7. The method for deodorizing a polyol according to claim 6, characterized in that: In the step (2), gas is introduced to cool the temperature during the second cooling, wherein the gas is nitrogen or compressed air.

8. The method for deodorizing a polyol according to claim 5 or 7, characterized in that: In the step (2), the second cooling time is 0.5 to 1.5 hours.

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