CN117720399A - Separation and purification method of 1, 3-propylene glycol - Google Patents
Separation and purification method of 1, 3-propylene glycol Download PDFInfo
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- CN117720399A CN117720399A CN202311485362.XA CN202311485362A CN117720399A CN 117720399 A CN117720399 A CN 117720399A CN 202311485362 A CN202311485362 A CN 202311485362A CN 117720399 A CN117720399 A CN 117720399A
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- YPFDHNVEDLHUCE-UHFFFAOYSA-N propane-1,3-diol Chemical compound OCCCO YPFDHNVEDLHUCE-UHFFFAOYSA-N 0.000 title claims abstract description 125
- 238000000034 method Methods 0.000 title claims abstract description 56
- 238000000926 separation method Methods 0.000 title claims abstract description 28
- 238000000746 purification Methods 0.000 title claims abstract description 13
- DNIAPMSPPWPWGF-VKHMYHEASA-N (+)-propylene glycol Chemical compound C[C@H](O)CO DNIAPMSPPWPWGF-VKHMYHEASA-N 0.000 claims abstract description 87
- 229920000166 polytrimethylene carbonate Polymers 0.000 claims abstract description 87
- 239000000463 material Substances 0.000 claims abstract description 85
- HGINCPLSRVDWNT-UHFFFAOYSA-N Acrolein Chemical compound C=CC=O HGINCPLSRVDWNT-UHFFFAOYSA-N 0.000 claims abstract description 38
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000007670 refining Methods 0.000 claims abstract description 23
- 238000000605 extraction Methods 0.000 claims abstract description 18
- 238000006703 hydration reaction Methods 0.000 claims abstract description 18
- VFTQJKSRDCKVQA-UHFFFAOYSA-N oxan-3-ylmethanol Chemical compound OCC1CCCOC1 VFTQJKSRDCKVQA-UHFFFAOYSA-N 0.000 claims abstract description 18
- 230000036571 hydration Effects 0.000 claims abstract description 17
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims abstract description 16
- LYTNHFVPHUPKGE-UHFFFAOYSA-N 2-(1,3-dioxan-2-yl)ethanol Chemical compound OCCC1OCCCO1 LYTNHFVPHUPKGE-UHFFFAOYSA-N 0.000 claims abstract description 15
- WERYXYBDKMZEQL-UHFFFAOYSA-N butane-1,4-diol Chemical compound OCCCCO WERYXYBDKMZEQL-UHFFFAOYSA-N 0.000 claims abstract description 12
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical compound OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229940043375 1,5-pentanediol Drugs 0.000 claims abstract description 7
- ALQSHHUCVQOPAS-UHFFFAOYSA-N Pentane-1,5-diol Chemical compound OCCCCCO ALQSHHUCVQOPAS-UHFFFAOYSA-N 0.000 claims abstract description 7
- DNIAPMSPPWPWGF-GSVOUGTGSA-N (R)-(-)-Propylene glycol Chemical compound C[C@@H](O)CO DNIAPMSPPWPWGF-GSVOUGTGSA-N 0.000 claims abstract description 6
- DNIAPMSPPWPWGF-UHFFFAOYSA-N monopropylene glycol Natural products CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229960004063 propylene glycol Drugs 0.000 claims abstract description 6
- 235000013772 propylene glycol Nutrition 0.000 claims abstract description 6
- HXJUTPCZVOIRIF-UHFFFAOYSA-N sulfolane Chemical compound O=S1(=O)CCCC1 HXJUTPCZVOIRIF-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000000895 extractive distillation Methods 0.000 claims description 21
- 238000010992 reflux Methods 0.000 claims description 8
- 235000011187 glycerol Nutrition 0.000 claims description 5
- 229940035437 1,3-propanediol Drugs 0.000 abstract description 77
- 239000012535 impurity Substances 0.000 abstract description 31
- 238000009835 boiling Methods 0.000 abstract description 11
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- 239000000203 mixture Substances 0.000 description 10
- 238000012827 research and development Methods 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 7
- 229920002215 polytrimethylene terephthalate Polymers 0.000 description 6
- DHKHKXVYLBGOIT-UHFFFAOYSA-N acetaldehyde Diethyl Acetal Natural products CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 description 4
- 150000001299 aldehydes Chemical class 0.000 description 4
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 210000002196 fr. b Anatomy 0.000 description 4
- 238000005984 hydrogenation reaction Methods 0.000 description 4
- -1 polytrimethylene terephthalate Polymers 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 3
- 125000002777 acetyl group Chemical class [H]C([H])([H])C(*)=O 0.000 description 3
- 230000006315 carbonylation Effects 0.000 description 3
- 238000005810 carbonylation reaction Methods 0.000 description 3
- 210000003918 fraction a Anatomy 0.000 description 3
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- GVNVAWHJIKLAGL-UHFFFAOYSA-N 2-(cyclohexen-1-yl)cyclohexan-1-one Chemical compound O=C1CCCCC1C1=CCCCC1 GVNVAWHJIKLAGL-UHFFFAOYSA-N 0.000 description 2
- RKXCKEHBMLDWET-UHFFFAOYSA-N 3,6-dihydro-2h-pyran-5-carbaldehyde Chemical compound O=CC1=CCCOC1 RKXCKEHBMLDWET-UHFFFAOYSA-N 0.000 description 2
- 101150065749 Churc1 gene Proteins 0.000 description 2
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 2
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- 229920001707 polybutylene terephthalate Polymers 0.000 description 2
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- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- UIJPWDSKPZLJAN-UHFFFAOYSA-N 2-(1,4-dioxan-2-yl)ethanol Chemical compound OCCC1COCCO1 UIJPWDSKPZLJAN-UHFFFAOYSA-N 0.000 description 1
- NPWYTMFWRRIFLK-UHFFFAOYSA-N 3,4-dihydro-2h-pyran-2-carbaldehyde Chemical compound O=CC1CCC=CO1 NPWYTMFWRRIFLK-UHFFFAOYSA-N 0.000 description 1
- AKXKFZDCRYJKTF-UHFFFAOYSA-N 3-Hydroxypropionaldehyde Chemical compound OCCC=O AKXKFZDCRYJKTF-UHFFFAOYSA-N 0.000 description 1
- 206010017472 Fumbling Diseases 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 1
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- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
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- YRVCHYUHISNKSG-UHFFFAOYSA-N propane-1,3-diol Chemical compound OCCCO.OCCCO YRVCHYUHISNKSG-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a separation and purification method of 1, 3-propylene glycol, which comprises the steps of 1) respectively inputting a first material and an extracting agent into an extraction rectifying tower, and extracting a second material from the top of the extraction rectifying tower and a third material from the bottom of the extraction rectifying tower; wherein the first material comprises 1, 3-propylene glycol, 3-hydroxymethyl tetrahydropyran and 1, 3-dioxane-2-ethanol, and is prepared by dealcoholizing, dehydrating, weightremoving and lightness removing materials prepared by adopting an acrolein hydration method; the extractant comprises one or more of diethylene glycol, triethylene glycol, 1, 5-pentanediol, 1, 2-propanediol, 1, 4-butanediol, sulfolane and glycerol; 2) And rectifying the third material in a refining tower to obtain 1, 3-propylene glycol product from the top of the tower. The invention adopts an extraction rectification mode to effectively separate impurities which have close boiling points and are difficult to separate from the 1,3-propanediol, thus obtaining a high-purity 1,3-propanediol product and improving the separation efficiency and yield of the 1, 3-propanediol; the invention has simple and convenient process flow and strong operability, and reduces the separation cost.
Description
Technical Field
The invention relates to the technical field of chemical industry, in particular to a separation and purification method of crude 1,3-propanediol obtained by an acrolein method.
Background
1,3-Propanediol (1, 3-Propanediol) is an important chemical raw material, can be used for synthesizing plasticizers, detergents, preservatives and emulsifying agents, or is used in industries such as foods, cosmetics and pharmacy, and the most main application is as a monomer and refined terephthalic acid (PTA) to synthesize a novel polyester material, namely polytrimethylene terephthalate (PTT). PTT has easy processability, good rebound resilience and pollution resistance, is easy to dye and wear-resistant, is widely used as a PTT fiber in the fields of carpets, engineering plastics, clothing fabrics and the like, has various physical and mechanical indexes and performances superior to those of polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and is known as a polyester king. Thus, the preparation and purification of 1,3-propanediol, an important raw material for the synthesis of PTT, has become a hotspot for the development of international synthetic fibers.
The industrial method for producing the 1,3-propanediol mainly comprises an ethylene oxide carbonylation method, a bioengineering method, acrolein hydration and the like, wherein the acrolein hydration yield is high, the safety coefficient is high, the equipment requirement is low, and the method is a competitive production method. The process route for preparing the 1,3-propanediol by the acrolein hydration method mainly comprises the following two steps:
(1) The acrolein is hydrated to obtain the allyl alcohol, and the reaction equation is CH 2 ＝CHCHO+H 2 O→CH 2 ＝CHCH 2 OH；
(2) The allyl alcohol and hydrogen are subjected to hydrogenation reaction to generate 1, 3-propylene glycol, and the reaction equation is CH 2 ＝CHCH 2 OH+H 2 →CH 2 OHCH 2 CH 2 OH。
Although acrolein hydration to produce 1,3-propanediol has high selectivity and conversion, the hydration reaction in this process inevitably produces aldehyde impurities, mainly including acetaldehyde, acrolein, 4-hetero-oxyheptanediol, 3, 4-dihydro-2H-pyran-2-carbaldehyde, 5, 6-dihydro-2H-pyran-3-carbaldehyde, etc., wherein 5, 6-dihydro-2H-pyran-3-carbaldehyde produces 3-hydroxymethyl tetrahydropyran during hydrogenation, and in addition, 1, 3-dioxane-2-ethanol is produced during hydrogenation, and 3-hydroxymethyl tetrahydropyran and 1, 3-dioxane-2-ethanol impurities have very close boiling points to those of 1,3-propanediol, which are difficult to separate by rectification, and the presence of these difficult-to-separate impurities affects the quality of 1,3-propanediol and further affects the quality of PTT.
In the prior art, impurities which are difficult to separate in materials prepared by adopting a chemical process (acrolein hydration or ethylene oxide carbonylation process) are removed through chemical reaction. Patent CN112979420a discloses a method for purifying 1,3-propanediol, which is to react aldehyde substances in raw materials under a specific pH condition to generate macromolecular substances, avoid generating aldehyde substances with boiling point close to that of 1,3-propanediol and difficult to separate, and effectively reduce the content of acetal impurity 3-hydroxymethyl tetrahydropyran in raw materials and remove trace aldehyde organic matters by combining with a resin adsorption step. CN1708467a discloses a method for removing impurities formed during the preparation of 1,3-propanediol, which is to treat a cyclic acetal containing a small amount of aldehyde groups, mainly to remove hydroxyethyldioxane (MW 132), by using acidic zeolite, acidic cation exchange resin or soluble acid, so as to achieve the purpose of removing acetal impurities, but the method may cause direct condensation of PDO itself to generate di-PDO or tri-PDO. The difficult-to-separate impurities in the material prepared by adopting the acrolein hydration are treated by the chemical treatment method, and although the acetal impurities are effectively removed, the reaction and separation process is increased, the operation difficulty is increased, the separation cost is increased, and in addition, side reactions are possibly caused to occur, so that the product yield is reduced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention discloses a method for separating and purifying 1,3-propanediol by extractive distillation, which can efficiently separate and remove difficult-to-separate impurities in materials prepared by acrolein hydration without introducing new chemical reaction, thereby improving the purity and yield of products and reducing the separation difficulty and cost.
In order to achieve the technical aim, the invention provides a separation and purification method of 1,3-propanediol, which comprises the following steps:
(1) Respectively inputting the first material and the extractant into an extraction rectifying tower, and extracting a second material from the top of the extraction rectifying tower and a third material from the bottom of the extraction rectifying tower; wherein the first material comprises 1, 3-propylene glycol, 3-hydroxymethyl tetrahydropyran and 1, 3-dioxane-2-ethanol, and is prepared by dealcoholizing, dehydrating, removing heavy weight and removing light weight of a material prepared by adopting an acrolein hydration method; the extractant comprises one or more of diethylene glycol, triethylene glycol, 1, 5-pentanediol, 1, 2-propanediol, 1, 4-butanediol, sulfolane and glycerol;
(2) And rectifying the third material by a refining tower, and then extracting a 1, 3-propylene glycol product from the top of the tower.
According to the invention, the boiling point of the target product 1,3-propanediol is 210-211 ℃, the boiling points of the difficult-to-separate impurities 3-hydroxymethyl tetrahydropyran and 1, 3-dioxane-2-ethanol contained in the first material are about 210-214 ℃, and it is easy to see that the target product and the difficult-to-separate impurities almost cannot be separated in a common rectification mode due to the close boiling points of the target product and the difficult-to-separate impurities. In order to simplify the process flow and avoid the material prepared by the acrolein hydration method by adding a chemical reaction mode, the research and development team of the invention develops a great deal of exploring experiments aiming at the method of separating impurities which are difficult to separate from the crude 1,3-propanediol material to be separated and purified by adopting a rectification mode.
The research and development team of the invention respectively carries out rectification separation experiments of 1,3-propanediol and 3-hydroxymethyl tetrahydropyran or 1, 3-dioxane-2-ethanol. Aiming at a system to be separated and purified of target products and difficult-to-separate impurities with different mass ratios, research and development team unexpectedly discovers the azeotropic phenomenon of the difficult-to-separate impurities and the target products in a rectifying and separating experiment, wherein the mass ratio of 1,3-propanediol in the azeotrope reaches 65% -85% or 70% -95%; in addition, the azeotropic system is found to be close to the boiling point of the target product, so that the loss of the target product is further increased; the loss rate of the target product in the whole rectifying and separating process reaches 39-77%. The course of this discovery experiment is shown in the pilot-scale examples of the present invention.
Based on the unexpected findings, the research and development team of the invention speculates that if the rectification is directly adopted to separate and purify the 1,3-propanediol (the first material), the process difficulty is higher, and more importantly, the 1,3-propanediol (the content of the 1,3-propanediol in the azeotrope is higher) of the target product with higher content is inevitably lost. In order to reduce the difficulty of rectification separation and improve the yield of target products, further, research and development groups explore refining rectification process conditions, perform organic combination of different rectification links, and attempt to add a third component as an extraction agent for rectification separation.
Based on a large number of fumbling experiments, research and development groups find that a polar organic solvent extractant similar to 1,3-propanediol is added into a first material, and a target product and impurities difficult to separate can be efficiently separated in a mode of combining extractive distillation and refined distillation, so that the loss of the target product can be effectively reduced, the yield is improved, and a high-purity 1,3-propanediol product is obtained.
In the technical scheme, the first material contains 1,3-propanediol, 3-hydroxymethyl tetrahydropyran which is difficult to separate and 1, 3-dioxane-2-ethanol, the water content in the first material is less than 1%, and light and heavy component impurities are removed. The second material is a mixture containing 1,3-propanediol and impurities which are difficult to separate, the content of the 1,3-propanediol in the mixture is lower than the content of the 1,3-propanediol of the azeotropic species in a pilot experiment, and the loss of the target product is effectively reduced on the premise of ensuring that the high-purity product is obtained by discharging the second material in the technical scheme of the invention.
Based on the technical scheme, the research and development team of the invention explores and optimizes the types and the dosage of the extractant. Optionally, the extractant includes one or more of diethylene glycol, triethylene glycol, 1, 5-pentanediol, 1, 2-propanediol, 1, 4-butanediol, sulfolane, glycerol. Further alternatively, when the extractant includes any two components of diethylene glycol, triethylene glycol, 1, 5-pentanediol, 1, 2-propanediol, 1, 4-butanediol, sulfolane, and glycerin, the mass ratio of any two components is 1 to 10.
Based on the technical scheme, the research and development team optimizes the feeding mass ratio of the first material to the extractant, and optionally, the feeding mass ratio of the first material to the extractant is 1: (0.5-20), further alternatively 1: (0.5-5).
Based on the technical scheme, the parameters and the process conditions of the extraction tower are optimized. Optionally, the theoretical plate number of the extractive distillation column is 30-60 theoretical plates, the feeding position of the first material is 25-40 plates from top, the feeding position of the extractant is 10-35 plates from top, and the reflux ratio is 0.5-10. Optionally, the operating pressure of the extraction rectifying tower is 1-200 kPa, the tower top temperature is 30-120 ℃, and the tower bottom temperature is 100-180 ℃.
Based on the technical scheme, the invention optimizes the technical characteristics of recycling the extractant. Optionally, a fourth material is extracted from the top of the refining tower, and the fourth material is returned to the extractive distillation tower as an extractant.
Based on the technical scheme, the parameters and the process conditions of the refining tower are optimized. Optionally, the theoretical plate number of the refining tower is 20-60 theoretical plates, the feeding position of the third material is 15-35 blocks from the top, and the reflux ratio is 0.5-10. Optionally, the operation pressure of the refining tower is 1-500 kPa, the tower top temperature is 30-120 ℃, and the tower bottom operation temperature is 100-180 ℃.
It should be noted that the structures and specifications of the extraction tower and the refining tower are not limited in the present invention, and those skilled in the art can select the extraction tower and the refining tower with the appropriate structures and specifications based on the technical scheme of the present invention, so that the technical schemes are all within the protection scope of the present invention.
The beneficial effects are that: compared with the prior art, the method effectively separates the impurities which are difficult to separate and have the boiling point close to that of the crude 1,3-propanediol prepared by adopting the acrolein hydration method by adopting the extraction rectification mode, obtains the high-purity 1,3-propanediol product, and improves the separation efficiency and the yield of the 1, 3-propanediol; the invention has simple and convenient process flow and strong operability, and reduces the separation cost.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 shows a process flow diagram of the separation and purification method of 1,3-propanediol of the present invention.
Wherein the above figures include the following reference numerals:
1-extraction rectifying tower and 2-refining tower.
Detailed Description
In order that the invention may be understood more fully, a more particular description of the invention will be rendered by reference to preferred embodiments thereof. It should be understood that these examples are for the purpose of more detailed description only and should not be construed as limiting the invention in any way, i.e., not intended to limit the scope of the invention.
Unless defined otherwise, technical terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. Relational terms such as "first," "second," "primary," "secondary," and the like may be used solely to distinguish one element from another element having the same name, and do not necessarily require or imply any such actual relationship or order between the elements. Features defining "first," "second," "primary," "secondary," etc. may include one or more of the features, either explicitly or implicitly, etc.
It should be noted that the specific steps for obtaining the first material used in the following examples are: separating 3-hydroxy propanal obtained by an acrolein hydration method, and then hydrogenating to obtain a 1, 3-propylene glycol primary product, wherein the 1, 3-propylene glycol primary product is dealcoholized, dehydrated, weightremoved and light removed to obtain a first material. The water content in the first material is less than 1%, and light and heavy component impurities are removed, but the first material contains impurities which are difficult to separate and form azeotropy with 1,3-propanediol (mainly tetrahydropyran-3-methanol and 1, 3-dioxane-2-ethanol) due to boiling points generated in the hydration, carbonylation and hydrogenation reaction processes; the mass ratio of the impurities difficult to separate is 3-10%, and the high-purity 1,3-propanediol product is difficult to obtain by simple rectification separation.
Pilot scale example
In this pilot scale example, experiments were performed on the separation of 1,3-propanediol from 3-hydroxymethyltetrahydropyran and 1, 3-dioxane-2-ethanol, respectively. Specific:
on the one hand, in a small test experiment of rectifying and separating 1,3-propanediol and 3-hydroxymethyl tetrahydropyran, a research and development team constructs a system for separating and purifying 1,3-propanediol and 3-hydroxymethyl tetrahydropyran with different mass ratios in a batch glass rectifying device, and the rectification is carried out under the pressure condition of 1-200 pa. Wherein, the proportion of 3-hydroxymethyl tetrahydropyran and 1, 3-propylene glycol in the system to be separated and purified is respectively 1: 20. 1: 50. 1:80.
during the experiment, the following steps are found: 1) When the temperature of the top of the column rises to 45-75 ℃, fraction A containing 3-hydroxymethyl tetrahydropyran is separated by first rectifying, and the fraction is a mixture of 1,3-propanediol and 3-hydroxymethyl tetrahydropyran; the composition analysis of the material A shows that the mass ratio of the 1,3-propanediol in the fraction A obtained by the to-be-separated and purified system with different mass ratios is 65-85 percent, the content is stable and unchanged, and the azeotrope of the 1,3-propanediol and the 3-hydroxymethyl tetrahydropyran is proved to be formed. 2) Further, as fraction A was continuously withdrawn, it was soon found that the content of 1,3-propanediol in the overhead product was continuously increased during the continued increase in the overhead temperature, and it was presumed that the boiling point of the azeotrope was very close to that of 1, 3-propanediol. 3) When the temperature rises to 60-85 ℃, the pure 1,3-propanediol is rectified and separated out of the system. In the whole rectification process, the loss rates of the 1,3-propanediol of the system to be separated and purified with different mass ratios respectively reach 77%, 51% and 43%.
On the other hand, in the small test of rectifying and separating 1,3-propanediol and 1, 3-dioxane-2-ethanol, a research and development team constructs a system for separating and purifying 1,3-propanediol and 1, 3-dioxane-2-ethanol with different mass ratios in a batch glass rectifying device, and the rectification is carried out under the pressure condition of 1-200 pa. Wherein, the proportion of 3-hydroxymethyl tetrahydropyran and 1, 3-propylene glycol in the system to be separated and purified is respectively 1: 30. 1: 60. 1:100.
during the experiment, the following steps are found: 1) When the temperature rises to 48-76 ℃, fraction B containing 1, 3-dioxane-2-ethanol is firstly rectified and separated, and the partial material is a mixture of 1,3-propanediol and 1, 3-dioxane-2-ethanol; the composition analysis of the fraction B shows that the mass ratio of the 1,3-propanediol in the fraction B obtained by the to-be-separated and purified system with different mass ratios is 70% -95% and the content is stable and unchanged, and the azeotrope of the 1,3-propanediol and the 1, 3-dioxane-2-ethanol is proved to be formed. 2) Further, as fraction B was continuously withdrawn, it was soon found that the content of 1,3-propanediol in the overhead product was continuously increased during the continued increase in the overhead temperature, and it was presumed that the boiling point of the azeotrope was very close to that of 1, 3-propanediol. 3) When the temperature rises to 60-85 ℃, the pure 1,3-propanediol is rectified and separated out of the system. In the whole rectification process, the loss rates of the 1,3-propanediol of the system to be separated and purified with different mass ratios reach 62%, 47% and 39% respectively.
Example 1
A separation and purification method of 1,3-propanediol is used for separating and purifying crude 1,3-propanediol material to be separated and purified by an acrolein hydration method, and an extractant is diethylene glycol.
Step (1): as shown in fig. 1, the first material and the extractant are respectively input into an extractive distillation column 1, and the second material is extracted from the top of the extractive distillation column 1, and the third material is extracted from the bottom of the extractive distillation column. The operating conditions of the extractive distillation column 1 are: 60 theoretical plates, wherein the feeding position of the first material is 30 th plate from the top, the feeding position of the extractant is 5 th plate from the top, and the reflux ratio is 5; the pressure at the top of the tower is 10Pa, the temperature at the top of the tower is 73.9 ℃, the temperature at the bottom of the tower is 131.4 ℃, the second material containing the impurities which are difficult to separate and the 1,3-propanediol is extracted from the top of the tower, and the third material containing the 1,3-propanediol and the extractant is extracted from the bottom of the tower.
Step (2): and rectifying the third material by a refining tower 2, and then extracting a 1, 3-propylene glycol product from the top of the tower. The operating conditions of the refining column 2 were: 55 theoretical plates and 20 plates at the feeding position; the pressure at the top of the tower is 2Pa, the temperature at the top of the tower is 79.4 ℃, the temperature at the bottom of the tower is 123.1 ℃, and the pure 1,3-propanediol product is produced at the top of the tower, and the purity is 99.97%; a fourth material containing 1, 3-propylene glycol and an extractant is extracted from the top of the refining tower 2, and the fourth material is returned to the top of the extractive distillation tower 1 as the extractant. The flow rates and compositions of the individual strands are shown in Table 1.
TABLE 1
Example 2
A separation and purification method of 1,3-propanediol is used for separating and purifying crude 1,3-propanediol material to be separated and purified by an acrolein hydration method, and an extracting agent is 1, 5-pentanediol.
Step (1): as shown in fig. 1, the first material and the extractant are respectively input into an extractive distillation column 1, and the second material is extracted from the top of the extractive distillation column 1, and the third material is extracted from the bottom of the extractive distillation column. The operating conditions of the extractive distillation column 1 are: 60 theoretical plates, wherein the feeding position of the first material is 35 th plate from the top, the feeding position of the extractant is 5 th plate from the top, and the reflux ratio is 5; the pressure at the top of the tower is 5Pa, the temperature at the top of the tower is 72.2 ℃, and the temperature at the bottom of the tower is 117.7 ℃; and (3) extracting a second material containing impurities which are difficult to separate from the 1,3-propanediol from the tower top, and extracting a third material containing the 1,3-propanediol and the extractant from the tower bottom.
Step (2): and rectifying the third material by a refining tower 2, and then extracting a 1, 3-propylene glycol product from the top of the tower. The operating conditions of the refining column 2 were: 55 theoretical plates and 20 plates at the feeding position; the pressure at the top of the refining tower 2 is 3Pa, the temperature at the top of the refining tower is 81.4 ℃, the temperature at the bottom of the refining tower is 127.9 ℃, the purity of the pure 1,3-propanediol product is 99.93%, a fourth material containing 1,3-propanediol and an extractant is extracted from the top of the refining tower 2, and the fourth material is returned to the top of the extractive rectifying tower 1 as the extractant. The flow rates and compositions of the individual strands are shown in Table 2.
TABLE 2
Example 3
The method is used for separating and purifying crude 1,3-propanediol materials to be separated and purified by an acrolein hydration method, wherein the extractant is a mixed extractant of diethylene glycol and triethylene glycol, and the mass ratio of the mixed extractant of diethylene glycol and triethylene glycol is 4:1.
step (1): as shown in fig. 1, the first material and the extractant are respectively input into an extractive distillation column 1, and the second material is extracted from the top of the extractive distillation column 1, and the third material is extracted from the bottom of the extractive distillation column. The operating conditions of the extractive distillation column 1 are: the theoretical plate number is 55, the feeding position of the first material is 30 th plate from the top, and the feeding position of the extractant is 5 th plate from the top; the reflux ratio is 5; the pressure at the top of the column is 3Pa, the temperature at the top of the column is 71.3 ℃, and the temperature at the bottom of the column is 129.8 ℃; and (3) extracting a second material containing impurities which are difficult to separate from the 1,3-propanediol from the tower top, and extracting a third material containing the 1,3-propanediol and the extractant from the tower bottom.
Step (2): and rectifying the third material by a refining tower 2, and then extracting a 1, 3-propylene glycol product from the top of the tower. The operating conditions of the refining column 2 were: 50 theoretical plates, 18 plates at the feeding position; the pressure at the top of the tower is 2Pa, the temperature at the top of the tower is 78.9 ℃, the temperature at the bottom of the tower is 124.5 ℃, and the purity of the pure 1,3-propanediol product produced at the top of the tower is 99.98%; a fourth material containing 1, 3-propylene glycol and an extractant is extracted from the top of the refining tower 2, and the fourth material is returned to the top of the extractive distillation tower 1 as the extractant. The flow rates and compositions of the individual strands are shown in Table 3.
TABLE 3 Table 3
The second material withdrawn from the top of the extractive distillation column 1 in examples 1 to 3, which contains impurities which are difficult to separate and part of the 1,3-propanediol, is discharged from the boundary zone.
Comparative example
In this comparative example, the first material was subjected to impurity separation by direct rectification. Specifically, the first material is input into a rectifying tower, and the operating conditions of the rectifying tower are as follows: 60 theoretical plates, wherein the feeding position of the first material is 30 th plate from the top, the feeding position of the extractant is 5 th plate from the top, and the reflux ratio is 5; the column top pressure was 9Pa, the column top temperature was 73.6℃and the column bottom temperature was 127.7 ℃. A fifth material containing impurities which are difficult to separate and 1,3-propanediol is extracted from the top of the rectifying tower, a pure 1,3-propanediol product of the 1,3-propanediol is extracted from the tower kettle, the purity is 99.91 percent, and the loss rate of the 1,3-propanediol is 39.38 percent. The flow rates and compositions of the individual strands are shown in Table 4.
TABLE 4 Table 4
As can be confirmed from examples 1-3 and comparative examples, the invention can efficiently separate target products and difficult-to-separate impurities by adding the extractant and separating and purifying the first material by means of extraction and rectification, thereby improving the separation and purification efficiency. Compared with the separation loss rate of 1,3-propanediol in the pilot experiment reaching 39-77%, the separation loss rate of 1,3-propanediol in the comparative example is 39.38%, and the separation loss rate of 1,3-propanediol in the embodiments 1-3 of the invention is 12-14%, so that the technical scheme of the invention can improve the yield while ensuring the purity of the high 1,3-propanediol product, thereby reducing the product loss and the separation cost. The technical scheme of the invention has simple process flow and high purification and separation yield, and is suitable for industrialized production of a large amount.
It should be noted that the above description of the present invention is further detailed in connection with specific embodiments, and it should not be construed that the present invention is limited to the specific embodiments; the size data of the embodiment is not limited to the technical scheme, but only shows one specific working condition. It will be apparent to those skilled in the art that several simple modifications and adaptations of the invention can be made without departing from the spirit of the invention and are intended to be within the scope of the invention.
Claims (10)
1. The separation and purification method of the 1,3-propanediol is characterized by comprising the following steps:
(1) Respectively inputting the first material and the extractant into an extraction rectifying tower, and extracting a second material from the top of the extraction rectifying tower and a third material from the bottom of the extraction rectifying tower; wherein the first material comprises 1, 3-propylene glycol, 3-hydroxymethyl tetrahydropyran and 1, 3-dioxane-2-ethanol, and is prepared by dealcoholizing, dehydrating, removing heavy weight and removing light weight of a material prepared by adopting an acrolein hydration method; the extractant comprises one or more of diethylene glycol, triethylene glycol, 1, 5-pentanediol, 1, 2-propanediol, 1, 4-butanediol, sulfolane and glycerol;
(2) And rectifying the third material by a refining tower, and then extracting a 1, 3-propylene glycol product from the top of the tower.
2. The method for separating and purifying 1,3-propanediol according to claim 1, wherein the extractant comprises any two components selected from the group consisting of diethylene glycol, triethylene glycol, 1, 5-pentanediol, 1, 2-propanediol, 1, 4-butanediol, sulfolane, and glycerin.
3. The method for separating and purifying 1,3-propanediol according to claim 2, wherein the mass ratio of any two components in the extractant is 1-10.
4. The method for separating and purifying 1,3-propanediol according to claim 1, wherein the feed mass ratio of the first material to the extractant is 1: (0.5-20).
5. The method for separating and purifying 1,3-propanediol according to claim 4, wherein the ratio of the first material to the extractant is 1: (0.5-5).
6. The method for separating and purifying 1,3-propanediol according to claim 1, wherein the theoretical plate number of the extractive distillation column is 30-60 theoretical plates, the feeding position of the first material is 25-40 plates from the top, the feeding position of the extractant is 10-35 plates from the top, and the reflux ratio is 0.5-10.
7. The method for separating and purifying 1,3-propanediol according to claim 1, wherein the operation pressure of the extractive distillation column is 1 to 200kPa, the column top temperature is 30 to 120 ℃, and the column bottom temperature is 100 to 180 ℃.
8. The method for separating and purifying 1,3-propanediol according to claim 1, wherein a fourth material is withdrawn from the top of the rectifying column, and the fourth material is returned to the extractive rectifying column as an extractant.
9. The method for separating and purifying 1,3-propanediol according to claim 1, wherein the theoretical plate number of the purification column is 20 to 60 theoretical plates, the feeding position of the third material is 15 to 35 from the top, and the reflux ratio is 0.5 to 10.
10. The process for separating and purifying 1,3-propanediol according to claim 1, wherein the operation pressure of the purifying column is 1 to 500kPa, the column top temperature is 30 to 120 ℃, and the column bottom operation temperature is 100 to 180 ℃.
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