CN115974651B - Method for preparing medical propylene glycol from propylene glycol prepared by transesterification method - Google Patents
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- CN115974651B CN115974651B CN202310009677.0A CN202310009677A CN115974651B CN 115974651 B CN115974651 B CN 115974651B CN 202310009677 A CN202310009677 A CN 202310009677A CN 115974651 B CN115974651 B CN 115974651B
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- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 title claims abstract description 447
- 238000000034 method Methods 0.000 title claims abstract description 63
- 238000005809 transesterification reaction Methods 0.000 title claims abstract description 25
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 198
- 235000019441 ethanol Nutrition 0.000 claims abstract description 61
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 52
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000000243 solution Substances 0.000 claims abstract description 32
- 238000010438 heat treatment Methods 0.000 claims abstract description 27
- 239000007788 liquid Substances 0.000 claims abstract description 26
- 238000003756 stirring Methods 0.000 claims abstract description 22
- 238000001179 sorption measurement Methods 0.000 claims abstract description 20
- 239000003463 adsorbent Substances 0.000 claims abstract description 18
- 239000007791 liquid phase Substances 0.000 claims abstract description 15
- 150000002148 esters Chemical group 0.000 claims abstract description 13
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000012153 distilled water Substances 0.000 claims abstract description 10
- 238000000926 separation method Methods 0.000 claims abstract description 7
- 239000008367 deionised water Substances 0.000 claims abstract description 5
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 5
- 238000004321 preservation Methods 0.000 claims abstract description 4
- 239000007864 aqueous solution Substances 0.000 claims abstract description 3
- 239000006228 supernatant Substances 0.000 claims description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 229910021536 Zeolite Inorganic materials 0.000 claims description 6
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 239000010457 zeolite Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000005119 centrifugation Methods 0.000 claims description 4
- 239000004927 clay Substances 0.000 claims description 2
- 239000005909 Kieselgur Substances 0.000 claims 1
- 239000012535 impurity Substances 0.000 abstract description 23
- 239000000203 mixture Substances 0.000 description 14
- 229910001385 heavy metal Inorganic materials 0.000 description 13
- 238000002156 mixing Methods 0.000 description 9
- 238000001914 filtration Methods 0.000 description 6
- 229910017053 inorganic salt Inorganic materials 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000003814 drug Substances 0.000 description 4
- 235000013305 food Nutrition 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229940079593 drug Drugs 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- KNKRKFALVUDBJE-UHFFFAOYSA-N 1,2-dichloropropane Chemical compound CC(Cl)CCl KNKRKFALVUDBJE-UHFFFAOYSA-N 0.000 description 1
- 241000208125 Nicotiana Species 0.000 description 1
- 235000002637 Nicotiana tabacum Nutrition 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 238000004383 yellowing Methods 0.000 description 1
Abstract
The invention discloses a method for preparing medical propylene glycol by using propylene glycol prepared by an ester exchange method, which comprises the following steps: (1) Dissolving the propylene glycol in absolute ethyl alcohol, stirring and standing; and then centrifugally separating, and collecting a liquid phase to obtain ethanol liquid of propylene glycol and dimethyl carbonate. (2) Adding deionized water or distilled water into the ethanol solution of propylene glycol and dimethyl carbonate, stirring and standing; and then centrifugally separating, and collecting a liquid phase to obtain an ethanol aqueous solution of propylene glycol. (3) And adding an adsorbent into the ethanol water solution of the propylene glycol, preserving heat under a heating condition, performing solid-liquid separation to remove the adsorbent after the completion of the heat preservation, and collecting a liquid phase to obtain an adsorption treatment liquid. (4) And adjusting the ratio of water to ethanol in the adsorption treatment liquid to reach an azeotropic ratio, and heating to azeotropically distill out the water and the ethanol to obtain the medical propylene glycol. The process utilizes the characteristic of propylene glycol produced by the transesterification method for preparing the dimethyl carbonate, and effectively reduces the impurity content of the propylene glycol.
Description
Technical Field
The invention relates to the technical field of preparation of medical-grade propylene glycol, in particular to a method for preparing medical-grade propylene glycol from propylene glycol prepared by an ester exchange method.
Background
Propylene glycol is an important nontoxic chemical raw material and is widely used in the food, medicine, cosmetics and tobacco industries. The production method of propylene glycol mainly comprises a propylene oxide hydration method, a 1, 2-dichloropropane method and an ester exchange method. The process mainly adopts propylene oxide hydration method and adopts transesterification to prepare dimethyl carbonate and co-produce propylene glycol, and the process adopts propylene carbonate and methanol to carry out normal pressure reaction at a low temperature of 70-80 ℃, so that the reaction is mild, the equipment investment is low, and the dimethyl carbonate with the same scale as the propylene glycol can be obtained, and the total yield of the propylene glycol of the process reaches more than 97 percent. It can be seen that the process for preparing dimethyl carbonate and co-producing propylene glycol by transesterification has great economic and technical advantages. However, impurities such as dimethyl carbonate, heavy metals, inorganic salts and the like exist in the propylene glycol prepared by the co-production of the transesterification method, and the phenomenon of yellowing of the colors after the propylene glycol is used at a higher temperature or stored for a long time is caused by the existence of the impurities, so that the application of the propylene glycol prepared by the process in the fields of medicines, foods and the like is limited.
Disclosure of Invention
In view of the above, the invention provides a method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, which effectively reduces the impurity content of propylene glycol produced by the ester exchange method by using the characteristics of dimethyl carbonate, so that the purity requirements of the fields of medicine, food and the like are better met. To achieve the above object, the present invention discloses the following aspects.
A method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, comprising the following steps:
(1) And dissolving the propylene glycol obtained in the process for preparing the dimethyl carbonate by the transesterification method in absolute ethyl alcohol, stirring and standing to separate out inorganic salts, heavy metals and other impurities in the propylene glycol. And then carrying out centrifugal separation, and collecting a liquid phase to obtain ethanol liquid of propylene glycol and dimethyl carbonate for later use.
(2) Adding deionized water or distilled water into the ethanol solution of propylene glycol and dimethyl carbonate, stirring, and standing to separate out the dimethyl carbonate. And then carrying out centrifugal separation, and collecting a liquid phase to obtain an ethanol water solution of propylene glycol for later use.
(3) Adding an adsorbent into the ethanol water solution of propylene glycol, preserving heat under a heating condition, performing solid-liquid separation to remove the adsorbent after the completion of the heat preservation, and collecting a liquid phase to obtain an adsorption treatment liquid for later use.
(4) And adjusting the ratio of water to ethanol in the adsorption treatment liquid to reach an azeotropic ratio, and heating to azeotropically distill out the water and the ethanol to obtain the medical propylene glycol.
Further, in the step (1), the volume ratio of the propylene glycol to the absolute ethanol is 1:1.5 to 1.8, wherein the propylene glycol and a small amount of dimethyl carbonate therein can be dissolved in absolute ethyl alcohol, and inorganic salts, heavy metals and other impurities are precipitated because of being insoluble.
Further, in the step (1), the standing time is 25-40 min so as to facilitate the precipitation of the precipitated impurities.
Further, in the step (1), the centrifugation speed is 10000-15000 r/min, the time is 10-15 min, and then the supernatant fluid is taken to obtain the ethanol solution of the propylene glycol and the dimethyl carbonate.
Further, in the step (2), the volume ratio of the ethanol solution of propylene glycol and dimethyl carbonate to deionized water or distilled water is 1:2.2 to 2.5. The dimethyl carbonate is difficult to dissolve in water, and the propylene glycol can be strongly dissolved in water, thereby capturing water molecules to precipitate the dimethyl carbonate.
Further, in the step (2), the standing time is 20-30 min so as to facilitate the precipitation of the precipitated impurities.
Further, in the step (2), the centrifugation speed is 8000-12000 r/min, the time is 10-15 min, and then the supernatant fluid is taken, so that the ethanol aqueous solution of the propylene glycol is obtained.
Further, in the step (3), the adding proportion of the adsorbent is 4-6.5 g/L; optionally, the adsorbent comprises any one of activated carbon, diatomite, natural zeolite powder, activated clay and the like. The adsorbent is used for further adsorbing impurities, so that the purity of the obtained propylene glycol is improved.
Further, in the step (3), the heating temperature is 40-50 ℃, and the heat preservation time is 15-25 min.
Further, in the step (4), ethanol is added to the adsorption treatment liquid, and the weight ratio of water to ethanol is adjusted to be 4.4:95.6, the heating temperature is 78.1 ℃, and the distilled mixture of the ethanol and the water is recovered as high-concentration ethanol.
Compared with the prior art, the invention has the beneficial effects that: the propylene glycol produced by the transesterification method for preparing the dimethyl carbonate contains impurities such as the dimethyl carbonate, heavy metals and the like, so that the purity of the propylene glycol is reduced, and the propylene glycol is difficult to meet the purity requirements in the fields of medicines, foods and the like. Therefore, the propylene glycol is firstly dissolved in the absolute ethyl alcohol by utilizing the component characteristics of the propylene glycol, and because the propylene glycol and the dimethyl carbonate impurities therein can be well dissolved in the ethanol, and the heavy metal and other impurities cannot be dissolved in the absolute ethyl alcohol, the heavy metal and other impurities in the propylene glycol can be effectively removed by utilizing the step. Further, the propylene glycol after the impurity removal is redissolved in water, and because the propylene glycol and the ethanol can be mutually dissolved with the water strongly, and the characteristic of strong hygroscopicity of the propylene glycol is added, water molecules can be greatly increased to separate out the dimethyl carbonate in the propylene glycol, so that the dimethyl carbonate is removed by the step. After the steps, industrial grade propylene glycol which is prepared by the transesterification method for preparing dimethyl carbonate and coproduced is converted into a mixture of propylene glycol, water and ethanol. Therefore, the invention further utilizes the azeotropic characteristic of ethanol and water to regulate the proportion of water and ethanol, and then heats the mixture at the azeotropic temperature, so that the heating temperature is low, the energy consumption is reduced, and the water and the ethanol in the propylene glycol can be removed at the same time, thereby obtaining the propylene glycol with high purity. In addition, the invention also treats the purified propylene glycol by using the adsorbent, thereby being beneficial to better improving the purity of the propylene glycol.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof. The invention will now be further illustrated by means of a specific implementation.
Example 1
A method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, comprising the following steps:
(1) Propylene glycol and absolute ethyl alcohol obtained in the process of preparing dimethyl carbonate by using a transesterification method are mixed according to a volume ratio of 1:1.7, stirring for 5min, and standing for 30min to separate out inorganic salt, heavy metal and other impurities in propylene glycol. The resulting mixture was then placed in a centrifuge and centrifuged at 12000 rpm for 10min. And taking the supernatant after completion to obtain ethanol solution of propylene glycol and dimethyl carbonate for later use.
(2) Mixing the ethanol solution of the propylene glycol and the dimethyl carbonate with distilled water according to the following ratio of 1:2.3, stirring for 3min after mixing, and standing for 25min to precipitate the dimethyl carbonate. The resulting mixture was then placed in a centrifuge and centrifuged at 10000 rpm for 15min. And taking the supernatant after completion to obtain an ethanol water solution of propylene glycol for later use.
(3) Adding active carbon into the ethanol water solution of propylene glycol, stirring and dispersing uniformly, wherein the adding proportion of the active carbon is 5g/L. And then heating to 45 ℃ and preserving heat for 20min, filtering to remove the adsorbent after the completion of the heating, and collecting a liquid phase to obtain an adsorption treatment liquid for later use.
(4) Adding ethanol into the adsorption treatment liquid, and adjusting the weight ratio of water to ethanol to be 4.4:95.6, heating at 78.1 ℃ to azeotropically distill out the water and the ethanol, thus obtaining the purified propylene glycol.
Example 2
A method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, comprising the following steps:
(1) Propylene glycol and absolute ethyl alcohol obtained in the process of preparing dimethyl carbonate by using a transesterification method are mixed according to a volume ratio of 1:1.5, stirring for 5min, and standing for 25min to separate out inorganic salt, heavy metal and other impurities in propylene glycol. The resulting mixture was then placed in a centrifuge and centrifuged at 10000 rpm for 15min. And taking the supernatant after completion to obtain ethanol solution of propylene glycol and dimethyl carbonate for later use.
(2) Mixing the ethanol solution of the propylene glycol and the dimethyl carbonate with distilled water according to the following ratio of 1:2.2, stirring for 3min after mixing, and standing for 20min to precipitate the dimethyl carbonate. The resulting mixture was then placed in a centrifuge and centrifuged at 8000 rpm for 15min. And taking the supernatant after completion to obtain an ethanol water solution of propylene glycol for later use.
(3) Adding diatomite into the ethanol water solution of propylene glycol, stirring and dispersing uniformly, wherein the adding proportion of the diatomite is 5g/L. And then heating to 40 ℃ and preserving heat for 25min, filtering to remove the adsorbent after the completion of the heating, and collecting a liquid phase to obtain an adsorption treatment liquid for later use.
(4) Adding ethanol into the adsorption treatment liquid, and adjusting the weight ratio of water to ethanol to be 4.4:95.6, heating at 78.1 ℃ to azeotropically distill out the water and the ethanol, thus obtaining the purified propylene glycol.
Example 3
A method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, comprising the following steps:
(1) Propylene glycol and absolute ethyl alcohol obtained in the process of preparing dimethyl carbonate by using a transesterification method are mixed according to a volume ratio of 1:1.8, stirring for 5min, and standing for 40min to separate out inorganic salt, heavy metal and other impurities in propylene glycol. The resulting mixture was then placed in a centrifuge and centrifuged at 15000 rpm for 10min. And taking the supernatant after completion to obtain ethanol solution of propylene glycol and dimethyl carbonate for later use.
(2) Mixing the ethanol solution of the propylene glycol and the dimethyl carbonate with distilled water according to the following ratio of 1:2.5, stirring for 3min after mixing, and standing for 30min to precipitate the dimethyl carbonate. The resulting mixture was then placed in a centrifuge and centrifuged at 12000 rpm for 15min. And taking the supernatant after completion to obtain an ethanol water solution of propylene glycol for later use.
(3) Adding natural zeolite powder into the ethanol water solution of propylene glycol, stirring and dispersing uniformly, wherein the adding proportion of the natural zeolite powder is 6.5g/L. And then heating to 50 ℃ and preserving heat for 15min, filtering to remove the adsorbent after completion, and collecting a liquid phase to obtain an adsorption treatment liquid for later use.
(4) Adding ethanol into the adsorption treatment liquid, and adjusting the weight ratio of water to ethanol to be 4.4:95.6, heating at 78.1 ℃ to azeotropically distill out the water and the ethanol, thus obtaining the purified propylene glycol.
Example 4
A method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, comprising the following steps:
(1) Propylene glycol and absolute ethyl alcohol obtained in the process of preparing dimethyl carbonate by using a transesterification method are mixed according to a volume ratio of 1:1.7, stirring for 5min, and standing for 30min to separate out inorganic salt, heavy metal and other impurities in propylene glycol. The resulting mixture was then placed in a centrifuge and centrifuged at 12000 rpm for 10min. And taking the supernatant after completion to obtain ethanol solution of propylene glycol and dimethyl carbonate for later use.
(2) Adding active carbon into the ethanol solution of propylene glycol and dimethyl carbonate, stirring and dispersing uniformly, wherein the adding proportion of the active carbon is 5g/L. And then heating to 45 ℃ and preserving heat for 20min, filtering to remove the adsorbent after the completion of the heating, and collecting a liquid phase to obtain an adsorption treatment liquid for later use.
(3) Heating the adsorption treatment liquid at 78.1 ℃ to evaporate the ethanol, thus obtaining the purified propylene glycol.
Example 5
A method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, comprising the following steps:
(1) Propylene glycol obtained in the process of preparing dimethyl carbonate by a transesterification method and distilled water are mixed according to the following ratio of 1:2.2, stirring for 3min after mixing, and standing for 20min to precipitate the dimethyl carbonate. The resulting mixture was then placed in a centrifuge and centrifuged at 8000 rpm for 15min. And taking the supernatant after completion to obtain an ethanol water solution of propylene glycol for later use.
(2) Adding diatomite into the ethanol water solution of propylene glycol, stirring and dispersing uniformly, wherein the adding proportion of the diatomite is 5g/L. And then heating to 40 ℃ and preserving heat for 25min, filtering to remove the adsorbent after the completion of the heating, and collecting a liquid phase to obtain an adsorption treatment liquid for later use.
(3) Adding water into the adsorption treatment liquid, wherein the weight ratio of water to ethanol is 4.4:95.6, heating at 78.1 ℃ to azeotropically distill out the water and the ethanol, thus obtaining the purified propylene glycol.
Example 6
A method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, comprising the following steps:
(1) Propylene glycol obtained in the process of preparing dimethyl carbonate by a transesterification method and distilled water are mixed according to the following ratio of 1:2.5, stirring for 3min after mixing, and standing for 30min to precipitate the dimethyl carbonate. The resulting mixture was then placed in a centrifuge and centrifuged at 12000 rpm for 15min. And taking supernatant after completion to obtain solution A for later use.
(2) Mixing the solution A with absolute ethyl alcohol according to a volume ratio of 1:1.8, stirring for 5min, and standing for 40min to separate out inorganic salt, heavy metal and other impurities in propylene glycol. The resulting mixture was then placed in a centrifuge and centrifuged at 15000 rpm for 10min. And taking supernatant after completion to obtain solution B.
(3) And adding natural zeolite powder into the solution B, stirring and dispersing uniformly, wherein the adding proportion of the natural zeolite powder is 6.5g/L. And then heating to 50 ℃ and preserving heat for 15min, filtering to remove the adsorbent after completion, and collecting a liquid phase to obtain an adsorption treatment liquid for later use.
(4) Adding ethanol into the adsorption treatment liquid, and adjusting the weight ratio of water to ethanol to be 4.4:95.6, heating at 78.1 ℃ to azeotropically distill out the water and the ethanol, thus obtaining the purified propylene glycol.
Performance testing
The various indexes of the purified propylene glycol prepared in the above examples were tested and the results are shown in the following table.
It can be seen that each index of the propylene glycol prepared in examples 1 to 3 satisfies the requirements of the pharmaceutical grade propylene glycol, and that part of the indexes of the propylene glycol prepared in examples 4 to 6 fail to satisfy the corresponding requirements. This is mainly because in examples 1 to 3, propylene glycol is first dissolved in absolute ethanol, and because propylene glycol itself and dimethyl carbonate impurities therein can be well dissolved in ethanol, but heavy metal and other impurities cannot be dissolved in absolute ethanol, the heavy metal and other impurities in propylene glycol can be effectively removed by this step. Further, the propylene glycol after the impurity removal is redissolved in water, and because the propylene glycol and the ethanol can be mutually dissolved with water strongly, and the propylene glycol has the characteristic of strong hygroscopicity, water molecules can be greatly increased to precipitate the dimethyl carbonate in the propylene glycol, so that the dimethyl carbonate is removed by the step. After the steps, industrial grade propylene glycol prepared by the transesterification method for preparing dimethyl carbonate is converted into a mixture of propylene glycol, water and ethanol, finally, the azeotropic characteristics of ethanol and water are utilized to adjust the proportion of water and ethanol, and then the water and the ethanol are heated at azeotropic temperature to be removed simultaneously, so that the propylene glycol with high purity is obtained.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A method for preparing medical grade propylene glycol by using propylene glycol prepared by an ester exchange method, which is characterized by comprising the following steps:
(1) Dissolving propylene glycol obtained in the process of preparing dimethyl carbonate by using the transesterification method in absolute ethyl alcohol, stirring and standing; then, carrying out centrifugal separation, and collecting a liquid phase to obtain ethanol liquid of propylene glycol and dimethyl carbonate for later use;
(2) Adding deionized water or distilled water into the ethanol solution of propylene glycol and dimethyl carbonate, stirring and standing; then, carrying out centrifugal separation, and collecting a liquid phase to obtain an ethanol water solution of propylene glycol for later use;
(3) Adding an adsorbent into the ethanol water solution of propylene glycol, preserving heat under a heating condition, performing solid-liquid separation to remove the adsorbent after the completion of the heat preservation, and collecting a liquid phase to obtain an adsorption treatment liquid for later use;
(4) Adjusting the ratio of water and ethanol in the adsorption treatment liquid to reach azeotropic ratio, and heating to azeotropically distill out the water and the ethanol to obtain medical-grade propylene glycol;
in the step (1), the volume ratio of the propylene glycol to the absolute ethyl alcohol is 1:1.5 to 1.8;
in the step (2), the volume ratio of the ethanol solution of the propylene glycol and the dimethyl carbonate to the deionized water or the distilled water is 1:2.2 to 2.5.
2. The method for preparing pharmaceutical grade propylene glycol from propylene glycol prepared by transesterification according to claim 1, wherein in step (1), the standing time is 25 to 40min.
3. The method for preparing medical grade propylene glycol by using propylene glycol prepared by transesterification according to claim 1, wherein in the step (1), the centrifugation rate is 10000-15000 rpm, the time is 10-15 min, and then the supernatant is taken to obtain the ethanol solution of propylene glycol and dimethyl carbonate.
4. The method for preparing pharmaceutical grade propylene glycol from propylene glycol prepared by transesterification according to claim 1, wherein in step (2), the standing time is 20 to 30min.
5. The method for preparing medical grade propylene glycol by using propylene glycol prepared by transesterification according to claim 1, wherein in the step (2), the centrifugation rate is 8000-12000 rpm for 10-15 min, and then the supernatant is taken to obtain the ethanol aqueous solution of propylene glycol.
6. The method for preparing pharmaceutical grade propylene glycol from propylene glycol prepared by transesterification according to claim 1, wherein in step (3), the adsorbent is added in a ratio of 4 to 6.5g/L.
7. The method for preparing medical grade propylene glycol from propylene glycol prepared by transesterification according to claim 1, wherein the adsorbent comprises any one of activated carbon, diatomaceous earth, natural zeolite powder, and activated clay.
8. The method for preparing medical grade propylene glycol by using propylene glycol prepared by transesterification according to claim 1, wherein in the step (3), the heating temperature is 40-50 ℃ and the holding time is 15-25 min.
9. The method for producing a pharmaceutical grade propylene glycol from propylene glycol produced by transesterification according to any one of claims 1 to 8, wherein in step (4), ethanol is added to the adsorption treatment liquid and adjusted to a weight ratio of water to ethanol of 4.4:95.6, the heating temperature is 78.1 ℃ and the temperature is heated to remove all ethanol.
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| CN101704719A (en) * | 2009-12-08 | 2010-05-12 | 湖南尔康制药有限公司 | Method for preparing medical-grade propylene glycol |
| CN105924350A (en) * | 2016-05-23 | 2016-09-07 | 屈强好 | Processing method for producing dimethyl carbonate byproduct pharmaceutical grade propylene glycol through transesterification method |
| CN106431840A (en) * | 2016-12-16 | 2017-02-22 | 阳煤集团青岛恒源化工有限公司 | Method of continuously extracting pharmaceutical grade propylene glycol and device thereof |
| CN111004092A (en) * | 2019-12-26 | 2020-04-14 | 岳阳昌德环境科技有限公司 | Method for separating dimethyl carbonate and methanol |
| CN114159816A (en) * | 2021-12-03 | 2022-03-11 | 铜陵金泰化工股份有限公司 | Processing device and process for preparing dimethyl carbonate and co-producing propylene glycol |
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2023
- 2023-01-04 CN CN202310009677.0A patent/CN115974651B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101704719A (en) * | 2009-12-08 | 2010-05-12 | 湖南尔康制药有限公司 | Method for preparing medical-grade propylene glycol |
| CN105924350A (en) * | 2016-05-23 | 2016-09-07 | 屈强好 | Processing method for producing dimethyl carbonate byproduct pharmaceutical grade propylene glycol through transesterification method |
| CN106431840A (en) * | 2016-12-16 | 2017-02-22 | 阳煤集团青岛恒源化工有限公司 | Method of continuously extracting pharmaceutical grade propylene glycol and device thereof |
| CN111004092A (en) * | 2019-12-26 | 2020-04-14 | 岳阳昌德环境科技有限公司 | Method for separating dimethyl carbonate and methanol |
| CN114159816A (en) * | 2021-12-03 | 2022-03-11 | 铜陵金泰化工股份有限公司 | Processing device and process for preparing dimethyl carbonate and co-producing propylene glycol |
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