CN116514637A - High-purity high-stability ethylene glycol refining process and application - Google Patents
High-purity high-stability ethylene glycol refining process and application Download PDFInfo
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- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 title claims abstract description 363
- 238000000034 method Methods 0.000 title claims abstract description 43
- 230000008569 process Effects 0.000 title claims abstract description 24
- 238000007670 refining Methods 0.000 title claims abstract description 14
- 238000002835 absorbance Methods 0.000 claims abstract description 48
- 238000010992 reflux Methods 0.000 claims abstract description 44
- 239000012535 impurity Substances 0.000 claims abstract description 34
- 239000003513 alkali Substances 0.000 claims abstract description 23
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000003860 storage Methods 0.000 claims abstract description 11
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 claims abstract description 3
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical group [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 28
- 239000000920 calcium hydroxide Substances 0.000 claims description 28
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 238000000746 purification Methods 0.000 claims description 10
- 239000002585 base Substances 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 5
- 238000004128 high performance liquid chromatography Methods 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 230000007423 decrease Effects 0.000 claims description 2
- 229920005989 resin Polymers 0.000 claims description 2
- 239000011347 resin Substances 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 abstract description 6
- 230000002378 acidificating effect Effects 0.000 abstract description 4
- 238000012824 chemical production Methods 0.000 abstract description 2
- 230000002035 prolonged effect Effects 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 52
- 239000002994 raw material Substances 0.000 description 20
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 15
- 230000000694 effects Effects 0.000 description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 9
- 238000009835 boiling Methods 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- 150000001336 alkenes Chemical class 0.000 description 6
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 6
- 229920000728 polyester Polymers 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 5
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 5
- 238000011049 filling Methods 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 239000003463 adsorbent Substances 0.000 description 4
- 238000004821 distillation Methods 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- 239000006227 byproduct Substances 0.000 description 3
- 239000003245 coal Substances 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000006703 hydration reaction Methods 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000006837 decompression Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 125000003172 aldehyde group Chemical group 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001339 alkali metal compounds Chemical class 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000002528 anti-freeze Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 235000009508 confectionery Nutrition 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000012043 crude product Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000006317 isomerization reaction Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 230000009965 odorless effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 238000004227 thermal cracking Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical compound OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/88—Separation; Purification; Use of additives, e.g. for stabilisation by treatment giving rise to a chemical modification of at least one compound
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a high-purity high-stability glycol refining process and application thereof, belonging to the technical field of chemical production, and comprising the following steps: s1, adding ethylene glycol with unqualified absorbance into alkali for reflux, wherein the addition amount of the alkali is 0.007-0.035% by weight, the reflux time is 12-45 minutes, and the alkali is alkaline earth metal hydroxide; s2, vacuum rectification: performing reduced pressure rectification on ethylene glycol with unqualified absorbance after the reflux, wherein the vacuum degree of the reduced pressure rectification is less than or equal to-0.090 MPa; the reflux ratio is 3-5: 5 to 7; s3, directly collecting all fractions in the step S2 to obtain an ethylene glycol product. The invention thoroughly removes impurities affecting absorbance in the product, and simultaneously maintains the system to be slightly alkaline so as to inhibit self-reaction carried out under an acidic condition, thus the quality of the product is deteriorated, the quality of the product is fundamentally improved, the storage period is prolonged, and the ethylene glycol product is directly stored in a sealed way, wherein the storage time is not less than 200 days.
Description
Technical Field
The invention relates to the technical field of chemical production, in particular to a high-purity high-stability ethylene glycol refining process and application.
Background
Ethylene glycol is colorless, odorless and sweet viscous liquid, and is an important organic chemical raw material. It has very wide application, and is mainly used for raw foodPolyester production, antifreeze, fine chemicals, and the like. Ethylene glycol is the chemical product with the largest import in China, and more than half of ethylene glycol is used for producing polyester. With the rapid development of domestic polyester and chemical fiber product markets, china has become the main production country and the largest consumption country of ethylene glycol in the world. At present, three process routes, namely a direct method, an olefin method and an oxalate method, mainly exist for preparing ethylene glycol by taking coal as a raw material at home. Because the direct method is difficult to realize automation and the cost of the olefin method is relatively high, the coal-to-glycol technology is mainly an oxalate reduction method and an olefin oxidation hydration method. The oxalate reduction method uses coal as raw material, and respectively obtains CO and H after gasification, transformation, purification, separation and purification 2 Wherein CO is synthesized and refined to produce oxalate through catalytic coupling, and the oxalate and H 2 Hydrogenation reaction is carried out, and polyester grade glycol is obtained after refining. The process flow is short, the cost is low, and the technology is the coal glycol technology which is the highest in attention in China at present, and the byproducts are mainly mono-glycol and glycol which are excessively reduced or incompletely reduced, ether formed by mutual dehydration between reduction products, and the like. The olefin oxidation hydrolysis method uses olefin as raw material, the olefin is catalyzed and oxidized to form ethylene oxide, the ethylene oxide and a large amount of water are hydrated to form ethylene glycol under the condition of a certain pressure and temperature, and the byproducts are mainly aldehyde and acid generated by isomerization of the ethylene oxide, di-ethylene glycol and tri-ethylene glycol with the boiling point higher than that of the ethylene glycol, and the like.
The ultraviolet absorbance of the ethylene glycol is an important index for detecting the quality of the high-purity ethylene glycol, and can reflect the impurity content in the ethylene glycol product. The quality of ethylene glycol is generally shown by the index internationally. The ethylene glycol with higher absorbance is used to influence the polyester catalyst in the polyester production process, so that the polyester resin is grey, and the gloss and chromaticity of the polyester product are influenced. An important item of Heng Lianggao pure glycol quality index is ultraviolet absorbance at 220nm, and factors affecting ultraviolet absorbance at 220nm may be aldehydes and acids. The product set time can have an effect on the UV value of the ethylene glycol product. The ultraviolet absorbance of the sample increases significantly as the standing time increases, probably because trace amounts of dissolved oxygen in the ethylene glycol product affect the ultraviolet absorbance of the product. In the subsequent production, how to remove the trace impurities such as aldehyde, acid, water and the like to improve the purity of the glycol is particularly important to ensure that the glycol is stably stored.
Patent document CN 107200678A discloses a method for removing aldehyde and purifying ethylene glycol, which comprises intermittently or continuously decompressing and rectifying ethylene glycol containing one or more impurities of water, acetic acid and aldehydes by using a rectifying tower, wherein the tower bottom temperature is 110-130 ℃, the tower top temperature is 70-105 ℃, the vacuum degree is 0.0960-0.0994 MPa, the rectifying tower 1 and the rectifying tower 2 are used for series operation to obtain qualified ethylene glycol products, the rectifying tower 1 is used for removing impurities of water, acetic acid, aldehydes and the like, the ethylene glycol obtained by the method has good storage property, all indexes of the ethylene glycol are qualified and stable, the aldehyde content can be controlled within a standard range, but the yield is very low. The patent document US4349417 a discloses a process for producing high-purity monoethylene glycol, wherein an alkali metal aqueous solution is added when a crude product of ethylene glycol prepared by hydration reaction of ethylene oxide and water is subjected to multiple-effect/multiple-evaporation water removal, the pH of the product is controlled within a range of 7-10, the multiple-effect/multiple-evaporation water removal is carried out and then the product is rectified, so that the high-purity monoethylene glycol with the light transmittance of more than 70% at 220nm is obtained, the hydration reaction of ethylene oxide generally requires excessive water to improve the reaction selectivity.
The usual purification method is also adsorption. The adsorption method is to remove impurities in glycol by utilizing the selective adsorption effect of the adsorbent, but the carbon material serving as the adsorbent is not active enough in nature, so that the improvement degree of the UV value of the glycol product is low, and the controllable range is narrow.
Disclosure of Invention
Aiming at the technical defects, the invention aims to provide a high-purity high-stability ethylene glycol refining process, which solves the problems of unqualified UV value and moisture and low yield in the prior art.
In order to solve the technical problems, the invention adopts the following technical scheme: a high-purity high-stability glycol refining process comprises the following steps:
s1, adding ethylene glycol with unqualified absorbance into alkali for reflux, wherein the addition amount of the alkali is 0.007-0.029% by weight, the reflux time is 12-45 minutes, and the alkali is alkaline earth metal hydroxide;
s2, vacuum rectification: performing reduced pressure rectification on ethylene glycol with unqualified absorbance after the reflux, wherein the vacuum degree of the reduced pressure rectification is less than or equal to-0.090 MPa; the reflux ratio is 3-5: 5 to 7;
s3, directly collecting the fraction in the step S2 to obtain an ethylene glycol product.
Preferably, the post-fraction after the end of the step S3 is not lower than 15% -30% of ethylene glycol with unqualified absorbance, more preferably, the post-fraction after the end of the step S3 is not lower than 20% -30% of ethylene glycol with unqualified absorbance, i.e. the positive fraction of the step S2 is collected in the step S3, and the post-fraction of 20% -30% is left in the step of vacuum rectification.
Preferably, the alkali addition amount in the step S1 is 0.007 to 0.025 percent by weight.
Preferably, the alkali addition amount in the step S1 is 0.01-0.025% by weight.
Preferably, the alkali addition amount in the step S1 is 0.01-0.02% by weight.
Preferably, the reflux time in the step S1 is 15 to 40 minutes.
Preferably, the reflux time in the step S1 is 20 to 45 minutes.
Preferably, the reflux time in the step S1 is 20 to 40 minutes.
Preferably, the reflux time in the step S1 is 20 to 30 minutes.
Preferably, the solubility of the base in water decreases with increasing temperature.
Preferably, the base is calcium hydroxide.
Preferably, the alkali in the step S1 is added in a solid form, the solid form is added, the step is simple, the water consumption is reduced, the energy saving and consumption reduction effects are obvious, and the downstream water treatment steps are reduced.
Preferably, the vacuum degree of the reduced pressure rectification is-0.090 to-0.095 MPa.
Preferably, the temperature of the top of the vacuum rectification tower is less than or equal to 103 ℃.
Preferably, the ethylene glycol product meets the requirements of high performance liquid chromatography.
Preferably, the ethylene glycol product has a moisture content of less than 0.034%; more preferably, the moisture content of the ethylene glycol product ranges from 0.010% to 0.034%; the absorbance at 220nm is lower than 0.174, and the yield of the ethylene glycol product qualified by the absorbance is more than or equal to 69 percent.
Preferably, the ethylene glycol product has a moisture content of less than 0.03%; more preferably, the moisture content of the ethylene glycol product ranges from 0.014% to 0.03%; absorbance at 220nm is lower than 0.163; the yield of the ethylene glycol product is more than or equal to 70 percent, and more preferably, the absorbance at 220nm is lower than 0.166.
Preferably, the absorbance at 220nm is below 0.154.
Preferably, the ethylene glycol product is directly stored in a sealed manner, and the storage time is not less than 200 days; more preferably, the ethylene glycol product is stored in a sealed condition directly for a period of not less than 180 days.
The invention also aims to provide an application of the high-purity high-stability ethylene glycol refining process, wherein the acquisition method is used for removing impurities from ethylene glycol with unqualified absorbance, and the yield of the ethylene glycol product with qualified absorbance is more than or equal to 69%.
Preferably, the ethylene glycol with unqualified absorbance is ethylene glycol with unqualified impurity content or absorbance in any process of production, use and storage, and the ethylene glycol with unqualified absorbance is ethylene glycol with unqualified impurity content or absorbance after any impurity removal process of resin and active carbon adsorption.
The invention has the beneficial effects that: 1. adding alkali and refluxing: adding alkali for reflux reaction before rectification to make a small amount of aldehyde impurities undergo condensation reaction under alkaline condition to generate high boiling point impurities, and removing the rear fraction to achieve the effect of removing impurities. Meanwhile, acidic substances are removed by adding alkali, and the ethylene glycol is relatively stable under the weak alkaline condition. The alkali adopted in the invention is calcium hydroxide, and compared with the common alkali metal compound, the calcium hydroxide ensures that the purification process is more stable and the yield is higher. The calcium hydroxide is added in an appropriate amount, too little can not completely remove impurities, too much can produce side impurities and is zoomed in the later stage of distillation due to too high concentration. Resulting in an increase in aldehyde group-containing byproducts in the product. Through experiments, the mass fraction of the calcium hydroxide is controlled to be 0.01-0.025%, the reflux time is controlled to be 20-40min, and the ethylene glycol after reduced pressure distillation meets the quality standard and has good long-time standing stability.
2. And (3) vacuum rectification: in ethylene glycol refining systems, small amounts of aldehydes are produced due to high temperature degradation. The higher the temperature is, the higher the generated impurities are, so that the product quality is reduced, the ethylene glycol product is influenced most at 220nm, and the absorbance tends to be obviously increased. The high temperature causes the product to be easily oxidized, so that the aldehyde content is increased, and other impurities are generated. Too high a distillation temperature can easily coke, which can cause thermal cracking of ethylene glycol products to ultimately lead to increased absorbance of the products at 220 nm. Reduced pressure rectification reduces boiling point temperature, reduces energy consumption, reduces production energy consumption and improves production efficiency; the decompression rectification can also prevent the leakage of harmful substances, reduce the damage to the health of human bodies, simultaneously avoid the exhaust emission under positive pressure and reduce the pollution to the environment. The vacuum rectification can avoid substances which are easy to decompose or polymerize at high temperature. Therefore, the method is a better purification mode for the vacuum rectification of the ethylene glycol with high boiling point. The vacuum degree of the system is controlled to be less than or equal to-0.090 MPa (the specific vacuum degree is-0.090 to-0.095 MPa), the boiling point is less than or equal to 103 ℃, and the high-purity ethylene glycol can be produced efficiently, with low consumption, safety and environmental protection.
3. And (3) water removal: because the ethylene glycol has high viscosity, the water removal effect of the adsorbent is poor and can only reach 0.15-0.2%, and impurities can be introduced into the adsorbent. The calcium hydroxide has the function of absorbing water, and then the water is removed again by vacuum rectification and utilizing the boiling point difference of water and glycol. The two modes are used for removing water simultaneously, the effect is better, the water content is lower than 0.04%, and other impurities are not introduced.
4. Stability: the stability of the ethylene glycol raw material is poor, the impurities are gradually increased after long-time storage, the storage time of the ethylene glycol raw material with qualified absorbance exceeds 3 days, and the condition of exceeding the standard can occur, so that the HPLC requirement can not be met. The stability of the ethylene glycol raw material can be improved by filling nitrogen into the ethylene glycol raw material, but after unsealing, the ethylene glycol raw material needs to be used once, if the ethylene glycol is used as a solvent in batches, the material is exposed to the air, and the product quality can be gradually deteriorated along with the unsealing time. The direct rectification can temporarily slightly reduce the absorbance of the raw material, the method has high requirement on the quality of the raw material on one hand, and has low yield which can only reach about 35 percent, the quality of the product can be gradually deteriorated, and the continuous or repeated reduced pressure rectification can slightly increase the yield, but greatly increases the energy consumption and the raw material loss. The method for distilling calcium hydroxide has low requirements on raw materials, can meet industrial products on the market, can increase the yield to more than 65%, solves the problem of product stability, and can be sustained and stabilized for more than 6 months.
5. And (3) reflux ratio adjustment: the reflux ratio is regulated by a reflux ratio controller, which mainly comprises an electromagnetic valve, a liquid separating hopper, a glass sight glass and the like. Reflux ratio=3 to 5 (loop): 5 to 7 (out), the control of the reflux ratio can improve the impurity separation effect with similar boiling points.
6. The aldehyde and acid impurities can not be thoroughly removed by simple rectification and purification, and the stability is poor. The storage under the protection of nitrogen atmosphere can improve the stability of the product, and the storage time is prolonged to about 1 month temporarily, so that the problem of product quality is not fundamentally solved. On the one hand, the method of calcium hydroxide rectification thoroughly removes impurities affecting absorbance in the product, and simultaneously maintains the ethylene glycol system to be slightly alkaline, inhibits self-reaction under acidic condition to cause the product quality to be poor, fundamentally improves the product quality and prolongs the storage period.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with table data in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1: and the mixture is directly refluxed and then decompressed and rectified without any additives.
3000g of ethylene glycol raw material with unqualified absorbance is fed, and the reflux ratio is as follows: 4 (loop): 6 (out), refluxing for 30min, and the vacuum degree is-0.090 to-0.095 MPa. Overhead temperature: the temperature is less than or equal to 103 ℃. Five fractions were collected and absorbance results of each fraction are shown in Table 1.
Table 1: direct vacuum rectification experimental data
Example 2: influence of the type of base on the absorbance of ethylene glycol.
Adding 500g of ethylene glycol with unqualified absorbance, adding 0.01% of alkali in the mass fraction of the ethylene glycol in a solid form, refluxing for 30min, rectifying under reduced pressure, and refluxing ratio: 4 (loop): 6 (out), the vacuum degree is-0.090 to-0.095 MPa. Overhead temperature: the temperature is less than or equal to 103 ℃. The results of the effect of the alkali species on the quality of the ethylene glycol product are shown in table 2.
Table 2: alkali species screening experimental data
Example 3: effect of the amount of calcium hydroxide on ethylene glycol absorbance.
Adding 500g of ethylene glycol with unqualified absorbance, adding calcium hydroxide with different proportions, refluxing for 30min, rectifying under reduced pressure, and refluxing ratio: 4 (loop): 6 (out), the vacuum degree is-0.090 to-0.095 MPa. Overhead temperature: the temperature is less than or equal to 103 ℃. The results of the effect of the amount of calcium hydroxide added on the quality of the ethylene glycol product are shown in Table 3.
Table 3: influence of the addition of calcium hydroxide on the quality of ethylene glycol products
Example 4: effect of reflux time on ethylene glycol absorbance.
500g of ethylene glycol is added, 0.01% of calcium hydroxide is added, and the mixture is subjected to vacuum rectification and reflux ratio: 4 (loop): 6 (out), the vacuum degree is-0.090 to-0.095 MPa, and the tower top temperature is as follows: the temperature is less than or equal to 103 ℃. The results of the effect of different reflux times on the quality of the ethylene glycol product are shown in table 3.
Table 4: influence of reflux time on quality of ethylene glycol product
From the experimental data of examples 1 to 4, it can be found that the impurities in the ethylene glycol can be removed and the absorbance can be reduced by adding calcium hydroxide for reflux during the vacuum rectification, and the absorbance can be reduced by direct vacuum rectification, but the overall yield is lower and the requirement on the quality of raw materials is higher. Meanwhile, on the detection data of the moisture, the direct vacuum rectification can remove the moisture from the front cut fraction through the difference of boiling points, but the moisture removal effect is poor. The effect of no calcium hydroxide treatment is obvious, the water content of glycol can be effectively reduced by rectification while the calcium hydroxide can absorb the water content, and the water content can be reduced to 0.01-0.04%.
Sodium hydroxide is used as a common alkali metal hydroxide and is used as an alkaline additive to participate in a reflux reaction, so that acidic impurities in ethylene glycol can be removed, but a final ethylene glycol product is easy to be disqualified, raw material loss is large, and yield is low, and probably because sodium hydroxide is heated for a long time, although aldehydes in ethylene glycol raw materials are easy to be catalyzed and removed, sodium hydroxide is easily dissolved in alcohols and is added in a solid form, the addition amount is difficult to control, other impurities are easy to be generated in the final product, and the absorption coefficient and yield of ethylene glycol are influenced.
In the research of adding calcium hydroxide, the calcium hydroxide is found to be beneficial to improving the quality of ethylene glycol products, compared with sodium hydroxide, the calcium hydroxide has low solubility in alcohol substances, the addition amount is controllable, the purification step is simple, the process is more stable, the water solubility of the calcium hydroxide is reduced along with the temperature rise, the impurity generation amount caused by the addition of alkali in the purification process is reduced when the ethylene glycol is purified, the raw material loss is reduced, and the yield is higher.
Too little calcium hydroxide can not completely remove impurities, and too much calcium hydroxide can introduce other impurities to affect the purity of the product. When the reflux time is short, the reaction is insufficient and impurities are not removed completely. If the reflow time is too long, other impurities are generated. Therefore, the amount of calcium hydroxide and the reflux time are strictly controlled, the amount of the added calcium hydroxide is 0.01-0.02% of the mass of the glycol, the reflux time is controlled to be 20-40min, and the glycol after reduced pressure distillation meets the quality standard.
Example 5: and comparing the stability of the glycol obtained by different methods at the normal temperature of 25 ℃.
5-1: the raw materials with qualified absorbance are directly placed in a sealing way without filling nitrogen, and the stability data are as follows:
5-2: the ethylene glycol product obtained by vacuum rectification after direct reflux of unqualified ethylene glycol raw material is directly placed in a sealed manner without filling nitrogen, and the stability data are as follows:
5-3: and (3) directly sealing and placing an ethylene glycol product obtained by vacuum rectification after the unqualified ethylene glycol is added with calcium hydroxide for reflux, and not filling nitrogen, wherein the stability data are as follows:
5-4: the stability data of the obtained ethylene glycol sample and qualified raw materials which are directly subjected to reflux, decompression and rectification are respectively filled with nitrogen for protection are as follows:
as can be seen from the experimental data in tables 5-1 to 5-3, the rectification of ethylene glycol by adding calcium hydroxide not only reduces the absorbance and improves the product quality, but also prolongs the stabilization time, and the product quality can be stabilized for more than 6 months continuously; as can be seen from tables 5 to 4, although the nitrogen filling can prolong the stabilization time, the duration is about 30 days, once the nitrogen in the bottle is gradually lost, the oxidized absorbance becomes large after the inside is occupied by air, and the product quality is affected. And the nitrogen gas is filled in to increase the resource consumption, the subsequent packaging is complicated, and the production efficiency is reduced.
The stability experimental data show that the production concepts of high quality, high stability, low consumption, high efficiency, safety and environmental protection can be better embodied by rectifying the glycol by calcium hydroxide.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (10)
1. The high-purity high-stability glycol refining process is characterized by comprising the following steps of:
s1, adding ethylene glycol with unqualified absorbance into alkali for reflux, wherein the addition amount of the alkali is 0.007-0.029% by weight, the reflux time is 12-45 minutes, and the alkali is alkaline earth metal hydroxide;
s2, vacuum rectification: performing reduced pressure rectification on ethylene glycol with unqualified absorbance after the reflux, wherein the vacuum degree of the reduced pressure rectification is less than or equal to-0.090 MPa; the reflux ratio is 3-5: 5 to 7;
s3, directly collecting the fraction in the step S2 to obtain an ethylene glycol product.
2. The process for refining high-purity and stable ethylene glycol according to claim 1, wherein the amount of alkali added in said step S1 is 0.007 to 0.025% by weight.
3. The process for refining high-purity and stable ethylene glycol according to claim 1, wherein the amount of alkali added in said step S1 is 0.01% to 0.025% by weight.
4. The process for purifying highly pure and stable ethylene glycol according to claim 1, wherein the reflux time in step S1 is 12 to 40 minutes.
5. The process for purifying highly pure and stable ethylene glycol according to claim 1 or 4, wherein the reflux time in step S1 is 20 to 40 minutes.
6. A process for purifying highly pure and stable ethylene glycol according to claim 1, wherein in step S1, the base is added in solid form, and the solubility of the base in water decreases with increasing temperature.
7. A process for refining high purity and stable ethylene glycol according to claim 1 or 6 wherein said base is calcium hydroxide.
8. The process for refining high-purity and high-stability ethylene glycol according to claim 1, wherein the ethylene glycol product meets the requirement of high performance liquid chromatography, the water content is lower than 0.034%, the absorbance at 220nm is lower than 0.174, and the ethylene glycol product is directly stored in a sealed manner for a storage time of not less than 200 days.
9. The use of a high purity and stable ethylene glycol purification process according to claim 1, wherein said process is used for removing impurities from ethylene glycol having unacceptable absorbance, said ethylene glycol product yield is greater than or equal to 69%.
10. The use of a high purity highly stable ethylene glycol purification process according to claim 9, wherein said unacceptable absorbance ethylene glycol is: and (3) producing, using and storing ethylene glycol with unqualified absorbance in any process, rectifying to remove impurities, and adsorbing ethylene glycol with unqualified absorbance after any impurity removal process by using resin and active carbon.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4349417A (en) * | 1980-01-18 | 1982-09-14 | Hoechst Aktiengesellschaft | Process for the manufacture of extremely pure monoethylene glycol |
| JP2001031606A (en) * | 1999-07-14 | 2001-02-06 | Nippon Shokubai Co Ltd | Purification of ethylene glycol |
| JP2011068699A (en) * | 2011-01-12 | 2011-04-07 | Nippon Shokubai Co Ltd | Purification method for ethylene glycol |
| JP2011213663A (en) * | 2010-03-31 | 2011-10-27 | Nippon Shokubai Co Ltd | Method for purifying ethylene glycol |
| CN103435446A (en) * | 2013-08-31 | 2013-12-11 | 安徽淮化股份有限公司 | Method and device for increasing chroma of finished ethylene glycol product |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4349417A (en) * | 1980-01-18 | 1982-09-14 | Hoechst Aktiengesellschaft | Process for the manufacture of extremely pure monoethylene glycol |
| JP2001031606A (en) * | 1999-07-14 | 2001-02-06 | Nippon Shokubai Co Ltd | Purification of ethylene glycol |
| JP2011213663A (en) * | 2010-03-31 | 2011-10-27 | Nippon Shokubai Co Ltd | Method for purifying ethylene glycol |
| JP2011068699A (en) * | 2011-01-12 | 2011-04-07 | Nippon Shokubai Co Ltd | Purification method for ethylene glycol |
| CN103435446A (en) * | 2013-08-31 | 2013-12-11 | 安徽淮化股份有限公司 | Method and device for increasing chroma of finished ethylene glycol product |
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