CN114920716A - Continuous production process and system of epoxy methyl ester - Google Patents
Continuous production process and system of epoxy methyl ester Download PDFInfo
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- CN114920716A CN114920716A CN202210472731.0A CN202210472731A CN114920716A CN 114920716 A CN114920716 A CN 114920716A CN 202210472731 A CN202210472731 A CN 202210472731A CN 114920716 A CN114920716 A CN 114920716A
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- 239000004593 Epoxy Substances 0.000 title claims abstract description 162
- 238000000034 method Methods 0.000 title claims abstract description 44
- 230000008569 process Effects 0.000 title claims abstract description 37
- 238000010924 continuous production Methods 0.000 title claims abstract description 29
- 150000004702 methyl esters Chemical class 0.000 title claims description 77
- 238000006243 chemical reaction Methods 0.000 claims abstract description 111
- 235000019387 fatty acid methyl ester Nutrition 0.000 claims abstract description 76
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 70
- 238000005406 washing Methods 0.000 claims abstract description 54
- 239000002351 wastewater Substances 0.000 claims abstract description 51
- 238000006735 epoxidation reaction Methods 0.000 claims abstract description 39
- 230000018044 dehydration Effects 0.000 claims abstract description 38
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 38
- 239000002994 raw material Substances 0.000 claims abstract description 34
- 238000000926 separation method Methods 0.000 claims abstract description 22
- -1 methyl epoxide Chemical class 0.000 claims abstract description 10
- 238000003825 pressing Methods 0.000 claims abstract description 10
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 84
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 68
- 239000000047 product Substances 0.000 claims description 49
- 239000002253 acid Substances 0.000 claims description 43
- 239000000463 material Substances 0.000 claims description 37
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 34
- 235000019253 formic acid Nutrition 0.000 claims description 34
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 30
- 229910052740 iodine Inorganic materials 0.000 claims description 30
- 239000011630 iodine Substances 0.000 claims description 30
- 239000003513 alkali Substances 0.000 claims description 29
- 230000002378 acidificating effect Effects 0.000 claims description 15
- 239000007788 liquid Substances 0.000 claims description 15
- 239000012043 crude product Substances 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- 239000012535 impurity Substances 0.000 claims description 5
- 238000002203 pretreatment Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 24
- 238000004801 process automation Methods 0.000 abstract 1
- 238000004065 wastewater treatment Methods 0.000 abstract 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- 208000005156 Dehydration Diseases 0.000 description 13
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 12
- 238000012432 intermediate storage Methods 0.000 description 11
- 235000021122 unsaturated fatty acids Nutrition 0.000 description 8
- 235000014113 dietary fatty acids Nutrition 0.000 description 7
- 238000007599 discharging Methods 0.000 description 7
- 239000000194 fatty acid Substances 0.000 description 7
- 229930195729 fatty acid Natural products 0.000 description 7
- 150000004665 fatty acids Chemical class 0.000 description 7
- 238000012544 monitoring process Methods 0.000 description 7
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- 125000005456 glyceride group Chemical group 0.000 description 6
- 235000011187 glycerol Nutrition 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 5
- 239000000920 calcium hydroxide Substances 0.000 description 5
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- 150000004668 long chain fatty acids Chemical class 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000004014 plasticizer Substances 0.000 description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 4
- 238000011085 pressure filtration Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 239000010775 animal oil Substances 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- 235000019198 oils Nutrition 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 235000012424 soybean oil Nutrition 0.000 description 3
- 239000003549 soybean oil Substances 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 235000015112 vegetable and seed oil Nutrition 0.000 description 3
- 239000008158 vegetable oil Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000012295 chemical reaction liquid Substances 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000002932 luster Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 231100000252 nontoxic Toxicity 0.000 description 2
- 230000003000 nontoxic effect Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000007127 saponification reaction Methods 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- LDVVTQMJQSCDMK-UHFFFAOYSA-N 1,3-dihydroxypropan-2-yl formate Chemical compound OCC(CO)OC=O LDVVTQMJQSCDMK-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 235000021588 free fatty acids Nutrition 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical class OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 description 1
- 239000008031 plastic plasticizer Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
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- 239000000344 soap Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
- C07D303/02—Compounds containing oxirane rings
- C07D303/38—Compounds containing oxirane rings with hydrocarbon radicals, substituted by carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals
- C07D303/40—Compounds containing oxirane rings with hydrocarbon radicals, substituted by carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals by ester radicals
- C07D303/42—Acyclic compounds having a chain of seven or more carbon atoms, e.g. epoxidised fats
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D301/00—Preparation of oxiranes
- C07D301/02—Synthesis of the oxirane ring
- C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
- C07D301/12—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with hydrogen peroxide or inorganic peroxides or peracids
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D301/00—Preparation of oxiranes
- C07D301/32—Separation; Purification
-
- 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
- Y02P20/10—Process efficiency
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Epoxy Compounds (AREA)
Abstract
The invention discloses a continuous production process of epoxidized fatty acid methyl ester, which comprises the following steps of: the crude fatty acid methyl ester is subjected to pretreatment, then pre-epoxidation and then an epoxy reaction, oil-water separation is carried out after the epoxy reaction is finished, and the oil phase is subjected to a steam stripping deacidification step, a vacuum dehydration step and a filter pressing step in sequence to obtain a methyl epoxide product. The invention realizes the full-process automation and continuity of the production process, has controllable production indexes and good product quality, and is easy for industrialized production. Compared with the traditional intermittent production process, the method has the advantages that the quality of the raw materials is controlled, the production wastewater is recycled, the consumption of the raw materials and the wastewater treatment difficulty are reduced, the epoxy reaction state of each kettle is kept unchanged and is more stable and controllable, alkaline washing and water washing are avoided in the post-treatment process, the product yield is improved, the labor intensity is reduced, and the generation of wastewater is avoided.
Description
Technical Field
The invention belongs to the technical field of plasticizer production, and particularly relates to a process method and a system for continuous production and post-treatment of epoxy methyl ester.
Background
The epoxy methyl ester is a nontoxic non-benzene environment-friendly plastic plasticizer which is widely applied at present, has double performances of plasticization and thermal stability, is nontoxic, safe and environment-friendly, is favored by the plastic product industry, and is widely applied in the industrial fields of plastics, coatings, novel high polymer materials, rubber and the like. Along with the improvement of environmental awareness of countries in the world, the toxicity of the plasticizer is more and more concerned by people; plasticizers phthalate esters are suspected of being carcinogenic, and their use in plastic products such as medical and food packaging, daily necessities, toys, etc. has been banned in many developed countries. And because the petroleum supply is slightly tight, the market price of the plasticizer is greatly increased internationally and domestically, and the raw material mainly utilized by the epoxy methyl ester is a renewable resource, so that the product has wide market prospect.
At present, the domestic production of epoxy methyl ester is carried out by an intermittent production process, the epoxy reaction is carried out through a kettle type stirring reactor, the water diversion treatment is carried out through a water diversion tank or a centrifugal machine, alkali washing and water washing are carried out after water diversion, and finally, dehydration treatment is carried out to obtain the finished epoxy methyl ester product. The existing stage adopts an intermittent method to prepare the methyl epoxide, the product quality is greatly influenced by manual operation, the product quality is not easy to control, the energy consumption of unit productivity is high, the post-treatment operation is complex, a large amount of waste water is easy to generate, and the production cost is high.
Meanwhile, the epoxy reaction is a strong exothermic reaction, the initial stage of the reaction is heated greatly in the process of adding hydrogen peroxide and formic acid, the heat exchange capacity of the reactor is limited, the hydrogen peroxide and the formic acid are slowly added for multiple times, the temperature of the hydrogen peroxide and the formic acid needs to be strictly controlled, particularly, the hydrogen peroxide and the formic acid are produced in summer, the temperature control difficulty is high, the temperature is easily over-heated, the product quality is influenced, and safety accidents such as material spraying of a reaction kettle can happen in severe cases.
Patent document No. CN113929643A discloses a continuous production process and system of epoxidized soybean oil, comprising an epoxidation step, a water separation treatment step, a deacidification treatment step and a dehydration treatment step which are sequentially performed, wherein the epoxidation step is continuously performed in two or more epoxy reaction kettles which are arranged in series; and (3) continuously carrying out water separation treatment on the epoxidized material through an overflow tank, carrying out continuous deacidification treatment on the water-separated material in a stripping tower, carrying out continuous dehydration treatment on the acid value up to the standard in a vacuum dehydration tower, and finally carrying out filter pressing to obtain the finished epoxidized soybean oil. The document solves the problems in the prior art to a certain extent by adopting a multi-kettle series connection mode to carry out epoxidation reaction.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and designs a continuous production method and a continuous production system which can realize continuous safe production, have controllable process indexes, reduce the consumption of personnel and energy, improve the quality of a cyclomethyl ester product and improve the yield of the product in order to improve the product quality, optimize the production process and reduce the production cost.
A continuous production process of epoxidized fatty acid methyl ester comprises the steps of raw material pretreatment, pre-epoxidation, epoxy reaction, standing water diversion, stripping deacidification, vacuum dehydration, product press filtration and the like which are sequentially carried out, and specifically comprises the following steps which are continuously carried out: the crude fatty acid methyl ester is subjected to pretreatment, then pre-epoxidation and then an epoxy reaction, oil-water separation is carried out after the epoxy reaction is finished, and the oil phase is subjected to a steam stripping deacidification step, a vacuum dehydration step and a filter pressing step in sequence to obtain a methyl epoxide product.
In the pretreatment step, the pretreatment mainly removes glycerin, glyceride, fatty acid and the like in the crude fatty acid methyl ester. Preferably, the pretreatment comprises alkali washing and water washing, glycerin, glyceride and fatty acid in the crude fatty acid methyl ester are removed through the pretreatment, and the acid value of the pretreated fatty acid methyl ester is less than or equal to 0.3 KOHmg/g. The fatty acid methyl ester raw material is relatively soybean oil, the product index is greatly floated, and the stability of the production device can be improved through pretreatment epoxy. Furthermore, by adopting the technical scheme, the quality of the product can be effectively ensured aiming at special raw materials such as waste animal and vegetable oil. The raw material fatty acid methyl ester crude product is generally obtained by rectifying waste animal and vegetable oil through ester exchange, and due to the complexity and the volatility of components of the waste animal and vegetable oil, the content fluctuation of substances such as glycerin, glyceride, fatty acid and the like in the fatty acid methyl ester crude product is large, even if the same batch of products are in different stages of rectification, the contents of the substances such as glycerin, glyceride, fatty acid and the like in the obtained product are different, the acid value fluctuation is too large, and the product quality is difficult to ensure during continuous production; the present invention can unify standards by utilizing preprocessing.
In the pre-epoxidation step, the pre-epoxidized fatty acid methyl ester raw material and a system liquid (mainly composed of formic acid, hydrogen peroxide and water) are subjected to pre-epoxidation reaction. Preferably, the acid value of the pre-epoxidized system liquid is 35-70KOHmg/g, the weight percentage content of hydrogen peroxide is 3-10%, and the use amount of the system liquid is 20-40% of the mass of the fatty acid methyl ester obtained after pretreatment.
Preferably, the pre-epoxy temperature is 60-80 ℃ (further preferably 70-80 ℃), and the reaction residence time is 5-7 h.
The pre-epoxidation according to the invention can be carried out with pure reagents, i.e. by adding hydrogen peroxide and formic acid, water, etc. The recovered spent acid solution may also be used. More preferably, the pre-epoxy system liquid is derived from acidic wastewater obtained by oil-water separation after the epoxy reaction. By adopting the technical scheme, the hydrogen peroxide and the formic acid in the epoxy acid solution can be further recovered, the utilization rate of raw materials is improved, the COD value of final wastewater can be further reduced, the biochemical treatment is easy, and the reaction temperature and the material consumption of subsequent epoxy reaction can be reduced.
Preferably, the pre-epoxy system liquid is from acidic wastewater obtained by oil-water separation after the epoxy reaction and stripping deacidification tower top condensation wastewater. By adopting the technical scheme, the utilization rate of raw materials is further improved. Meanwhile, COD in the wastewater is mainly derived from formic acid, hydrogen peroxide, dissolved epoxy fatty acid methyl ester, saponified epoxy fatty acid methyl ester and the like, the amount of formic acid and hydrogen peroxide can be reduced by re-epoxidation of the wastewater, and the saponification of the epoxy methyl ester and the dissolution of the epoxy fatty acid methyl ester can be further avoided by matching with stripping operation. From the source, the generation of COD source is reduced.
Preferably, the acid value of the system liquid is 45-60KOHmg/g, the content of hydrogen peroxide is 4.5-7% by weight, and the using amount of the system liquid is 28-32% of the mass of the fatty acid methyl ester obtained after pretreatment.
After the pre-oxidation is finished, in a test stage or before production, the charging ratio of hydrogen peroxide to formic acid in the epoxidation reaction is determined by detecting the iodine value and the like of a pre-epoxy product.
Preferably, the epoxy reaction is continuously performed in 5 or more than 5 epoxy reaction kettles which are arranged in series, the residence time of each kettle is 2-5 h, the temperature is 60-80 ℃, wherein hydrogen peroxide and formic acid are continuously added into the previous 2-4 reaction kettles respectively for 2-4 times (for example, the materials are equally divided into n parts and then continuously added into the previous n epoxy reaction kettles respectively as the preference), and the weight ratio of the raw materials is as follows: methyl ester: hydrogen peroxide: formic acid 100: 25-35: 3.5-5.5, wherein the concentration of the hydrogen peroxide is 40-60%, and the concentration of the formic acid is 70-90%.
Preferably, the materials after the epoxy reaction enter a standing tank, the standing time is 1-3 h, standing and water separation are carried out, and the wastewater is separated and used for the pre-epoxy reaction of the fatty acid methyl ester.
Preferably, in the stripping deacidification step, one or more stripping towers arranged in series are adopted, the stripping towers adopt low-pressure steam, the steam consumption is 1-10% (more preferably 1-5%) of the flow of the crude epoxy fatty acid methyl ester, the temperature of the stripped epoxy fatty acid methyl ester is 90-110 ℃, acidic substances are removed by adopting a vacuum countercurrent contact mode, and the vacuum degree is 0.08-0.1 MPa.
Preferably, the vacuum dehydration step is to perform continuous dehydration in a vacuum dehydration tower, wherein the vacuum degree is 0.09MPa to 0.1MPa and the temperature is less than 110 ℃.
Preferably, in the pressure filtration step, clay or diatomite is used for removing insoluble impurities contained in the epoxidized fatty acid methyl ester.
Preferably, the crude fatty acid methyl ester is C16-C20 fatty acid methyl ester, and the iodine value ranges from 90 to 120.
Preferably, the iodine value of the epoxy methyl ester product is less than 5, the acid value is less than 0.5KOHmg/g, and the moisture is less than 0.1%.
Preferably, the continuous production process of the epoxy methyl ester comprises the following steps:
(1) pretreating raw material methyl ester (the raw material methyl ester refers to fatty acid methyl ester) to remove substances such as glycerin, glyceride and fatty acid by alkali washing and water washing;
(2) pre-epoxidizing the pretreated raw material methyl ester and the wastewater obtained by standing, and recycling formic acid and hydrogen peroxide contained in the wastewater;
(3) after the pre-epoxidized methyl ester is subjected to water diversion, an epoxy reaction is carried out, the epoxy reaction is continuously carried out in 5 or more than 5 epoxy reaction kettles which are connected in series, the residence time of each kettle is 2-5 h, the temperature is 60-80 ℃, wherein hydrogen peroxide and formic acid are respectively and continuously dripped for 2-4 times to carry out the reaction kettle, and the weight ratio of the raw materials is as follows: methyl ester: hydrogen peroxide: formic acid 100: 25-35: 3.5-5.5, wherein the concentration of the hydrogen peroxide is 40-60%, and the concentration of the formic acid is 70-90%.
(4) Standing and water dividing are carried out after the epoxy reaction is finished, the residence time is 1-3 h, and the wastewater is separated according to liquid level change and is used for the pre-epoxy reaction of methyl ester; the crude product of the epoxy methyl ester obtained by separation enters the next working procedure;
(5) stripping and deacidifying the crude product of the methyl epoxide by adopting one or more series-connected deacidifying stripping towers, wherein the deacidifying stripping towers adopt low-pressure steam, the steam temperature is 120-150 ℃, the steam consumption is about 1-10 percent of the flow of the crude product of the methyl epoxide, acidic substances are removed by adopting a vacuum countercurrent contact mode, and the vacuum degree is 0.08-0.1 MPa.
(6) And after the steam stripping is finished, performing vacuum dehydration, wherein the vacuum degree is 0.09MPa to 0.1MPa, and the temperature of a dehydration tower is less than 110 ℃ (more preferably 80 ℃ to 110 ℃). Then obtaining the product through pressure filtration.
In the present invention, the step numbers (1) to (6) are not limited to the reaction sequence, and are provided only for distinguishing each technical feature.
In the epoxidation step, in each epoxy reaction kettle, the reaction liquid accounts for 1/2-4/5 of the volume of the epoxy reaction kettle, which is generally the volume of the kettle. And a matched stirring device is arranged in each epoxy reaction kettle to ensure the stable and rapid reaction of materials.
Preferably, the total residence time in the epoxidation step is 15 to 20 hours.
Preferably, when the quality index of the final discharge does not meet the requirement, the final material can be ensured to meet the final quality requirement by increasing the number of the epoxy reaction kettles, or by increasing the reaction time or supplementing the material and the like. The volume of the finally added epoxy reaction kettle can be properly reduced so as to further improve the utilization rate of the device, for example, a terminal reaction kettle with the volume of about 1/4-1/2 can be added at the discharge hole of the last epoxy reaction kettle.
Preferably, 3-7 epoxy reaction kettles connected in series (preferably 5-6 epoxy reaction kettles connected in series) are adopted for carrying out the epoxidation reaction, wherein the temperature of the epoxy reaction kettle in which hydrogen peroxide and formic acid are required to be dripped is controlled to be 60-70 ℃, the residence time of each epoxy reaction kettle is 2-6 hours (more preferably 3-5 hours), the temperature of the heat-preservation reaction kettle (in which hydrogen peroxide and formic acid are not dripped) is controlled to be 75-80 ℃, and the residence time of each epoxy reaction kettle is 2-6 hours (more preferably 3-5 hours).
Preferably, the deacidification step is carried out by adopting one or more series-connected deacidification stripping towers, the deacidification stripping towers adopt superheated low-pressure steam, the steam temperature is 120-150 ℃, vacuum deacidification is adopted, and the vacuum degree is 0.08-0.1 MPa.
Acid value monitoring is carried out on the stripped and deacidified material at set time intervals; when the acid value is higher, part of solid alkali is added in the filter pressing step to remove acid.
Preferably, after the deacidification step is finished, the acid value of the material is 0.3-0.45; preferably, the invention can adopt countercurrent continuous dehydration treatment and a tower structure to enhance the dehydration speed and the dehydration efficiency, and after the dehydration step is finished, the moisture content of the material is 0.02-0.05%.
After the epoxidation reaction, the iodine value of the product is less than 5.
A continuous production system of epoxidized fatty acid methyl ester comprises a pretreatment unit, a pre-epoxy kettle, an epoxy unit with a plurality of kettles connected in series, a standing tank, a stripping tower, a vacuum dehydration tower and a filter press which are connected in sequence;
the pretreatment unit is used for pretreating a fatty acid methyl ester crude product;
the pre-epoxy kettle is used for pre-epoxy the pretreated fatty acid methyl ester;
the epoxy unit is used for carrying out epoxidation reaction on the pre-epoxidized material;
the standing tank is used for realizing oil-water separation of the materials after the epoxy reaction is finished;
the stripping tower is used for stripping and deacidifying the oil phase separated out from the standing tank;
the vacuum dehydration tower is used for dehydrating the epoxy fatty acid methyl ester subjected to steam stripping deacidification;
the filter press is used for removing impurities from the dehydrated epoxidized fatty acid methyl ester.
Preferably, the acid wastewater outlet of the standing tank is connected with an intermediate storage tank; and a system liquid feed inlet of the pre-epoxy kettle is connected with the intermediate storage tank through a pipeline provided with a dosimeter.
Preferably, the gas phase outlet of the stripping tower is connected with a condensing heat exchanger, and the condensate outlet of the condensing heat exchanger is simultaneously connected with the intermediate storage tank.
Preferably, the product outlet of the stripping tower is connected with an intermediate product storage tank, and the outlet of the product storage tank is connected with the material inlet of the filter press. By utilizing the technical scheme, on one hand, the collection of the product of the stripping tower is realized, and meanwhile, the monitoring of the acid value of the product is also facilitated. When the acid value is monitored according to a set time interval, if the acid value is not satisfactory, solid alkali (namely, argil or alkaline argil with the volume of 10: 0.5-2 of diatomite and calcium hydroxide) can be added into a filter press to remove free fatty acid in the argil or the alkaline argil.
Preferably, the pretreatment unit comprises an alkaline washing tank and a water washing tank, one or two standing tanks are arranged at the same time, the pretreatment unit is firstly stirred and mixed with alkaline liquor in the alkaline washing tank, the concentration of the used alkaline liquor is 1-3 wt%, the flow rate of the alkaline liquor is 2-5% of the flow rate of fatty acid methyl ester, and the used alkali is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate and is added in the form of aqueous solution. The alkaline washing residence time is 20-60 min, the alkaline washing discharged material enters a standing tank, the residence time of the standing tank is 1-3 h, the methyl ester enters a washing tank after standing and water separation, the water consumption is 2-5% of the flow of the methyl ester, the residence time of the washing is 20-60 min, the washing discharged material enters the standing tank, and the residence time of the standing tank is 1-3 h.
The invention adopts a full-section continuous production process, has mild reaction conditions, controllable production indexes, good product quality, simple process, low requirement on production equipment and easy industrial production, and the flow chart is shown in figure 1.
In order to further embody the advantages of the present invention, the advantages of the present invention compared with the prior art are illustrated:
the pretreatment of raw material methyl ester (fatty acid methyl ester) can ensure the stability of raw material indexes, reduce the contents of glycerin, glyceride and fatty acid and reduce the side reaction of epoxy, wherein, the reduction of the content of monoglyceride can improve the oil-water layering efficiency, and the reduction of the content of fatty acid can reduce the acid value of products. Compared with the original process, the production stability can be ensured, and the problems of over-standard acid value, difficult wastewater separation and the like are avoided.
And (II) pre-epoxidation, namely, pre-epoxidation is carried out by using residual formic acid and hydrogen peroxide in the epoxy wastewater, so that the raw materials of formic acid and hydrogen peroxide in the wastewater can be fully utilized, the methyl ester iodine value after pre-epoxidation is reduced, the use amount of formic acid and hydrogen peroxide in the epoxy reaction stage can be reduced, and compared with the original process, the use amount of formic acid and hydrogen peroxide can be reduced by 5-10%.
And (III) epoxy reaction, the configuration of the epoxy reaction kettle can be optimized by adopting continuous multi-kettle series connection, the volume of the epoxy reaction kettle is reduced, the heat exchange area is increased, the reaction efficiency is improved on the premise of temperature control, and the reaction temperature can be improved and deep epoxy can be realized because the reaction heat in the heat-insulating epoxy reaction kettle is smaller. The reaction temperature, the heat release quantity and the material state relative temperature of each reaction kettle, and the production control is relatively simple. When the traditional intermittent production is adopted, the hydrogen peroxide and formic acid cannot be normally added for reaction due to the limitation of heat exchange capacity in the production process, and the hydrogen peroxide and formic acid need to be added for multiple times, so that the reaction temperature is not over-temperature.
And (IV) stripping deacidification is carried out, so that the product quality is improved: no new impurities are introduced, the flash point is increased, and the smell is reduced; the product yield is improved: the ineffective saponification in the alkali washing process is reduced, and the loss caused by product dissolution in the alkali washing and water washing processes is reduced; the wastewater generation is reduced: the soap-containing wastewater generated in the processes of alkali washing and water washing is avoided; raw material recovery: the formic acid contained in the crude epoxy methyl ester can be recycled;
and (V) monitoring the quality index of continuous production: the invention adopts multi-kettle series reaction, when the iodine value of the outlet does not reach the standard, a supplementary epoxy reaction kettle can be arranged for continuous reaction, the volume and the residence time of the supplementary epoxy reaction kettle can be properly shortened, and the device for supplementing hydrogen peroxide is arranged, so that the product can reach the standard and the previous reaction and the addition of raw materials are not influenced. When the acid value of vacuum deacidification is not up to the standard, secondary deacidification/tertiary deacidification can be set, and discharging is carried out after the acid value is up to the standard. If abnormal conditions still occur and the acid value can not be reduced, alkali can be properly added for deacidification in the filter pressing process. Therefore, the device has stronger adjustability and adaptability and is more beneficial to controlling the quality of the final product.
In the traditional intermittent production process, the post-treatment process is work with high manual strength, water is required to be divided for many times, the water dividing operation is greatly influenced by human factors, a part of products are put into wastewater to generate loss, and in addition, in the process of adding alkali liquor, the difference of the excess degree is also caused by people, and the loss is also high. The continuous production process of the invention does not need direct operation of personnel, after setting of each process index is finished, only the product index needs to be measured and reaches the standard, if the product index does not reach the standard, secondary treatment is carried out according to the relevant operation flow which does not reach the standard until the product index reaches the standard, so that loss caused by personnel operation does not exist.
The invention adopts a full-section continuous production process, has mild reaction conditions, controllable production indexes, good product quality, simple process and low requirement on production equipment, and is easy for industrialized production.
Drawings
FIG. 1 is a schematic process flow diagram and system diagram employed in an embodiment of the present invention.
Detailed Description
In order to make the technical scheme of the present invention clearer and clearer, the present invention is further explained with reference to the accompanying drawings and embodiments:
fig. 1 is a process flow partially adopted in the embodiment of the invention, and a continuous production process of epoxidized fatty acid methyl ester, which comprises the steps of raw material pretreatment, pre-epoxidation, epoxidation reaction, standing for water separation, stripping deacidification, vacuum dehydration, product press filtration and the like, so as to obtain an epoxidized methyl ester (i.e. epoxidized fatty acid methyl ester) finished product.
As shown in fig. 1, a continuous production system of epoxidized fatty acid methyl ester comprises a pretreatment unit, a pre-epoxidation reactor, an epoxidation unit with multiple reactors connected in series, a standing tank, a stripping tower, a vacuum dehydration tower and a filter press which are connected in sequence;
the pretreatment unit is used for pretreating the fatty acid methyl ester crude product; the pretreatment unit comprises an alkaline washing tank and a water washing tank, a middle standing tank is arranged between the alkaline washing tank and the water washing tank, the standing tank is arranged behind the water washing tank, the alkaline washing tank and the water washing tank are respectively provided with a fatty acid methyl ester crude product inlet, an alkaline liquor/water washing inlet, a wastewater outlet and a material outlet, and the inlets are respectively connected with the fatty acid methyl ester crude product raw material tank, the alkaline liquor tank, the water storage tank and the like through pipelines. The outlet of the alkaline washing tank is connected with the inlet of the intermediate standing tank, the outlet of the water washing tank is connected with the standing tank (not shown in the figure), and the waste water outlet of the standing tank is connected with the waste water treatment center.
The pre-epoxy kettle is used for pre-epoxy the pretreated fatty acid methyl ester; the inlet of the pre-epoxy kettle is connected with the material outlet of the pretreatment unit through a pipeline. The waste water outlet of the pre-epoxy kettle is connected with a waste water treatment center through a pipeline. An acid liquor inlet of the pre-epoxy kettle is connected with an intermediate storage tank, and the intermediate storage tank is used for collecting waste acid liquor generated after epoxy and condensate generated by steam stripping. And a material outlet of the pre-epoxy kettle is connected with a feed inlet of the epoxy unit.
The epoxy unit is used for carrying out epoxidation reaction on the pre-epoxidized material; the epoxy unit consists of 5 or more than 5 epoxy reaction kettles which are arranged in series. And introducing the reaction liquid of the epoxy unit into a standing tank to finish standing and water diversion.
The standing tank is used for realizing oil-water separation of the materials after the epoxy reaction is finished; and the acid wastewater is collected into an intermediate storage tank from an outlet in a centralized manner and is used by a pre-epoxy unit.
And the stripping tower is used for stripping and deacidifying the oil phase separated out from the standing tank. The stripping waste water can also be simultaneously introduced into an intermediate storage tank for pre-epoxy reaction.
The vacuum dehydration tower is used for dehydrating the stripped and deacidified epoxy fatty acid methyl ester;
the filter press is used for removing impurities of the dehydrated epoxy fatty acid methyl ester.
The process is further described below:
pretreatment of raw materials: raw material methyl ester (namely unsaturated long-chain fatty acid methyl ester with an iodine value of 90-120, mainly containing C16-C20 unsaturated fatty acid methyl ester and taking C18 unsaturated fatty acid methyl ester as a main component) is fed through a metering pump, enters a pretreatment unit, is stirred and mixed with alkali liquor, the concentration of the used alkali liquor is 1-3 wt%, the flow rate of the alkali liquor is 2-5% of the flow rate of the methyl ester, and the used alkali is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate and is added in the form of aqueous solution. The alkaline washing residence time is 20-60 min, the alkaline washing discharged material enters a standing tank, the residence time of the standing tank is 1-3 h, the methyl ester enters a washing tank after standing and water distribution, the water consumption is 2-5% of the flow of the methyl ester, the residence time of the washing is 20-60 min, the washing discharged material enters the standing tank, the residence time of the standing tank is 1-3 h, the discharging is pretreated after standing, and the pretreated wastewater enters a wastewater treatment center.
(1) Pre-epoxy: and (3) feeding the pretreated methyl ester (fatty acid methyl ester) into a pre-epoxidation kettle, mixing and stirring the pretreated methyl ester (fatty acid methyl ester) with separated acidic wastewater after the epoxy reaction is finished, and carrying out pre-epoxidation reaction on the condensed wastewater at the top of a stripping tower (the acid value of the wastewater is about 45-60KOHmg/g, the content of hydrogen peroxide is 4.5-7%, and the amount of the wastewater is about 28-32% of the mass of the methyl ester). The pre-epoxy temperature is 60-80 ℃, and the reaction residence time is 5-7 h.
(2) And (3) epoxy reaction: through 5-7 kettles connected in series for epoxy reaction, formic acid and hydrogen peroxide are uniformly dripped into the first three-four kettles for 3-4 times according to the proportion, the reaction temperature of the first three-four kettles is controlled to be 60-65 ℃, the residence time is 3-5 hours, the reaction temperature of the fourth-fifth kettles or the fifth-sixth kettles is controlled to be 75-80 ℃, the residence time is 3-5 hours, and the iodine value is measured after the fifth kettle or the sixth kettle is discharged, wherein the iodine value is required to be less than 5, and if the problem of high iodine value occurs, the reaction residence time of the fifth kettle or the sixth kettle can be increased, and the indexes are qualified. And (4) after the epoxy reaction is finished, allowing the mixture to enter a standing tank for water separation to obtain crude epoxy methyl ester.
(3) Stripping and deacidifying: preheating crude epoxy methyl ester after epoxy water distribution to 90-120 ℃, feeding the crude epoxy methyl ester into a stripping tower, controlling the vacuum degree of the stripping tower at-0.08 to-0.1 MPa, controlling the tower temperature at 80-110 ℃, controlling the steam consumption to be 1-5% of the feeding flow of the crude epoxy methyl ester, discharging from the bottom of the stripping tower, feeding the crude epoxy methyl ester into an intermediate storage tank, and monitoring the acid value every 2 hours.
Vacuum dehydration and filter pressing: feeding the stripped methyl ester into a vacuum dehydration tower, controlling the temperature to be 100-110 ℃, controlling the vacuum degree to be-0.9-0.1 MPa and controlling the outlet water content to be less than or equal to 0.1%, performing pressure filtration on the product after dehydration, and adding part of solid alkali (such as argil and alkaline argil with the ratio of 10:1 of calcium hydroxide) into a pressure filter for adsorbing redundant acidic substances when the stripped acid value is greater than 0.5.
Example 1:
pretreatment of raw materials: raw material methyl ester (namely unsaturated long-chain fatty acid methyl ester with an iodine value of 110, mainly containing C16-C20 unsaturated fatty acid methyl ester and taking C18 unsaturated fatty acid methyl ester as a main component) is fed through a metering pump, enters a pretreatment unit, and is stirred and mixed with alkaline liquor in an alkaline washing tank, wherein the concentration of the used alkaline liquor is 2 wt%, the flow rate of the alkaline liquor is 4% of the flow rate of the methyl ester, and the used alkali is sodium hydroxide aqueous solution. The alkaline washing residence time is 40min, the alkaline washing discharged material enters an intermediate standing tank, the residence time of the intermediate standing tank is 2h, the methyl ester enters a washing tank after standing and water splitting, the water consumption is 4% of the flow of the methyl ester, the water washing residence time is 40min, the water washing discharged material enters the standing tank, the residence time of the standing tank is 2h, the discharging material is discharged after standing to complete pretreatment, and the pretreated wastewater enters a wastewater treatment center.
(1) Pre-epoxy: the pretreated methyl ester (fatty acid methyl ester) enters a pre-epoxy kettle, and is mixed and stirred with separated acidic wastewater after the epoxy reaction is finished, and condensation wastewater at the top of a stripping tower (the acid value of the wastewater is about 50KOHmg/g, the content of hydrogen peroxide is 6 percent, and the amount of the wastewater is about 30 percent of the mass of the methyl ester) is subjected to pre-epoxy reaction. The pre-epoxy temperature is 70 ℃, and the reaction residence time is 5 h.
(2) And (3) epoxy reaction: through 6-kettle series epoxy reaction, formic acid and hydrogen peroxide are uniformly dripped in the first 4 kettles for 4 times according to the proportion, the reaction temperature of the first four kettles is controlled to be 60-65 ℃, the residence time is controlled to be 3 hours respectively, the reaction temperature of the fifth kettle and the sixth kettle is controlled to be 75-80 ℃, the residence time is 3 hours respectively, iodine value measurement is carried out after the sixth kettle is discharged, the iodine value is required to be less than 5, if the problem of high iodine value occurs, the reaction residence time of the sixth kettle can be increased, and the index is guaranteed to be qualified. And (4) after the epoxy reaction is finished, allowing the mixture to enter a standing tank for water separation to obtain crude epoxy methyl ester.
(3) Stripping and deacidifying: preheating the crude epoxy methyl ester after the water diversion of the epoxy resin is finished to 100 ℃, feeding the crude epoxy methyl ester into a stripping tower, controlling the vacuum degree of the stripping tower to be-0.09 MPa, controlling the tower temperature to be 90 ℃, controlling the steam consumption to be 3% of the feeding flow of the crude epoxy methyl ester, discharging the crude epoxy methyl ester from the bottom of the stripping tower, feeding the crude epoxy methyl ester into an intermediate storage tank, and monitoring the acid value every 2 hours.
Vacuum dehydration and filter pressing: feeding the stripped methyl ester into a vacuum dehydration tower, controlling the temperature to be 100-110 ℃, the vacuum degree to be-0.9 MPa, controlling the water content at an outlet to be less than or equal to 0.1%, performing pressure filtration on the product after dehydration, and adding part of solid alkali (such as argil and alkaline argil of calcium hydroxide 10: 1) into a pressure filter for adsorbing redundant acidic substances when the stripped acid value is more than 0.5. The product performance test data is shown in the following table:
| item | Measured value | Standard value of |
| Acid value KOHmg/g | 0.36 | ≤0.5 |
| Iodine number I 2 g/100g | 4.1 | ≤5 |
| Water content% | 0.06 | ≤0.1 |
| Color and luster Pt-CO | 60 | ≤80 |
| Epoxy value g/100g | 5.45 | ≥5.2 |
Note: the raw materials with different iodine values and the epoxy values of products have different requirements
Example 2:
pretreatment of raw materials: raw material methyl ester (namely unsaturated long-chain fatty acid methyl ester with an iodine value of 100, mainly containing C16-C20 unsaturated fatty acid methyl ester and taking C18 unsaturated fatty acid methyl ester as a main component) is fed through a metering pump, enters a pretreatment unit and is stirred and mixed with alkali liquor, the concentration of the used alkali liquor is 2 wt%, the flow of the alkali liquor is 4% of the flow of the methyl ester, and the used alkali is sodium hydroxide aqueous solution. The alkaline washing residence time is 40min, the alkaline washing discharged material enters a standing tank, the residence time of the standing tank is 2h, the methyl ester enters a washing tank after standing and water diversion, the water consumption is 4% of the flow of the methyl ester, the residence time of the washing is 40min, the washing discharged material enters the standing tank, the residence time of the standing tank is 2h, the discharged material is pretreated after standing, and the pretreated wastewater enters a wastewater treatment center.
(1) Pre-epoxy: the pretreated methyl ester (fatty acid methyl ester) enters a pre-epoxy kettle, and is mixed and stirred with separated acidic wastewater after the epoxy reaction, and condensed wastewater at the top of a stripping tower (the acid value of the wastewater is about 48KOHmg/g, the content of hydrogen peroxide is 5.5%, and the amount of the wastewater is about 28% of the mass of the methyl ester) to carry out pre-epoxy reaction. The pre-epoxy temperature is 75 ℃, and the reaction residence time is 5 h.
(2) And (3) epoxy reaction: through 5 kettles connected in series for epoxy reaction, formic acid and hydrogen peroxide are uniformly dripped in the first three kettles for 3 times according to the proportion, the reaction temperature of the first three kettles is controlled to be 60-65 ℃, the residence time is 4 hours respectively, the reaction temperature of the fourth kettle and the fifth kettle is controlled to be 75-80 ℃, the residence time is 3 hours respectively, the iodine value is measured after the fifth kettle is discharged, the iodine value is required to be less than 5, if the problem of high iodine value occurs, the reaction residence time of the fifth kettle can be increased, and the indexes are qualified. And (4) after the epoxy reaction is finished, allowing the mixture to enter a standing tank for water separation to obtain crude epoxy methyl ester.
(3) Stripping and deacidifying: preheating the crude epoxy methyl ester after the water diversion of the epoxy resin is finished to 110 ℃, feeding the crude epoxy methyl ester into a stripping tower, controlling the vacuum degree of the stripping tower to be-0.092 MPa, controlling the tower temperature to be 93 ℃, controlling the steam consumption to be 2% of the feeding flow of the crude epoxy methyl ester, discharging the crude epoxy methyl ester from the bottom of the stripping tower, feeding the crude epoxy methyl ester into an intermediate storage tank, and monitoring the acid value every 2 hours.
Vacuum dehydration and filter pressing: the stripped methyl ester enters a vacuum dehydration tower, the temperature is controlled to be 100-110 ℃, the vacuum degree is controlled to be-0.9 MPa, the outlet water content is controlled to be less than or equal to 0.1%, products are filtered by pressure after dehydration, and when the stripping acid value is more than 0.5, partial solid alkali (such as argil and alkaline argil of calcium hydroxide in a ratio of 10: 1) can be added into a pressure filter for adsorbing redundant acidic substances. The product performance test data is shown in the following table:
| item | Measured value | Standard value |
| Acid value KOHmg/g | 0.32 | ≤0.5 |
| Iodine number I 2 g/100g | 3.9 | ≤5 |
| Water content% | 0.07 | ≤0.1 |
| Color Pt-CO | 60 | ≤80 |
| Epoxy value g/100g | 5.05 | ≥4.8 |
Note: the epoxy value of the product is different from that of the raw material with different iodine values.
Example 3:
pretreatment of raw materials: raw material methyl ester (namely unsaturated long-chain fatty acid methyl ester with an iodine value of 90, mainly containing C16-C20 unsaturated fatty acid methyl ester and taking C18 unsaturated fatty acid methyl ester as a main component) is fed through a metering pump, enters a pretreatment unit and is stirred and mixed with alkali liquor, the concentration of the used alkali liquor is 2 wt%, the flow of the alkali liquor is 4% of the flow of the methyl ester, and the used alkali is sodium hydroxide aqueous solution. The alkaline washing residence time is 40min, the alkaline washing discharged material enters a standing tank, the residence time of the standing tank is 2h, the methyl ester enters a washing tank after standing and water diversion, the water consumption is 4% of the flow of the methyl ester, the residence time of the washing is 40min, the washing discharged material enters the standing tank, the residence time of the standing tank is 2h, the discharged material is pretreated after standing, and the pretreated wastewater enters a wastewater treatment center.
(1) Pre-epoxy: and (3) feeding the pretreated methyl ester (fatty acid methyl ester) into a pre-epoxidation kettle, mixing the pretreated methyl ester (fatty acid methyl ester) with separated acidic wastewater after the epoxy reaction is finished, and stirring the condensed wastewater at the top of a stripping tower (the acid value of the wastewater is about 45KOHmg/g, the content of hydrogen peroxide is 4.3%, and the amount of the wastewater is about 26% of the mass of the methyl ester) to perform pre-epoxidation reaction. The pre-epoxy temperature is 80 ℃, and the reaction residence time is 5 hours.
(2) And (3) epoxy reaction: through 4-kettle series epoxy reaction, formic acid and hydrogen peroxide are uniformly dripped in the first two kettles for 2 times according to the proportion, the reaction temperature of the first two kettles is controlled to be 60-65 ℃, the residence time is controlled to be 5 hours respectively, the reaction temperature of the third kettle and the fourth kettle is controlled to be 75-80 ℃, the residence time is 3 hours respectively, iodine value measurement is carried out after the fourth kettle is discharged, the iodine value is required to be less than 5, if the problem of high iodine value occurs, the reaction residence time of the fourth kettle can be increased, and the index is guaranteed to be qualified. And (4) after the epoxy reaction is finished, allowing the mixture to enter a standing tank for water separation to obtain crude epoxy methyl ester.
(3) Stripping and deacidifying: preheating crude epoxy methyl ester after the water diversion of epoxy is finished to 120 ℃, feeding the crude epoxy methyl ester into a stripping tower, controlling the vacuum degree of the stripping tower at-0.095 MPa, controlling the tower temperature at 95 ℃, controlling the steam dosage to be 1% of the feeding flow of the crude epoxy methyl ester, discharging from the bottom of the stripping tower, feeding the crude epoxy methyl ester into an intermediate storage tank, and monitoring the acid value every 2 hours.
Vacuum dehydration and filter pressing: the stripped methyl ester enters a vacuum dehydration tower, the temperature is controlled to be 100-110 ℃, the vacuum degree is controlled to be-0.9 MPa, the outlet water content is controlled to be less than or equal to 0.1%, products are filtered by pressure after dehydration, and when the stripping acid value is more than 0.5, partial solid alkali (such as argil and alkaline argil of calcium hydroxide in a ratio of 10: 1) can be added into a pressure filter for adsorbing redundant acidic substances. The product performance test data is shown in the following table:
| item | Measured value | Standard value of |
| Acid value KOHmg/g | 0.34 | ≤0.5 |
| Iodine number I 2 g/100g | 4.3 | ≤5 |
| Water content% | 0.06 | ≤0.1 |
| Color and luster Pt-CO | 60 | ≤80 |
| Epoxy value g/100g | 4.65 | ≥4.5 |
Note: the epoxy value of the product is different from that of the raw material with different iodine values.
In comparison to the prior art (no pre-oxidation step, single pot batch reaction for the epoxidation step, and alkaline and water wash for the carboxylic acid stripping step), the procedure of example 1 was used to produce 1 ton of epoxidized fatty acid methyl esters with the following results:
as can be seen from Table 1, the method of the present invention can effectively save the consumption of formic acid and hydrogen peroxide, and simultaneously can effectively reduce the amount of wastewater and the COD content in the wastewater.
Claims (12)
1. A continuous production process of epoxidized fatty acid methyl ester is characterized by comprising the following steps which are carried out continuously: the crude fatty acid methyl ester is subjected to pretreatment, then pre-epoxy reaction and then epoxy reaction, oil-water separation is performed after the epoxy reaction is finished, and the oil phase is subjected to a steam stripping deacidification step, a vacuum dehydration step and a filter pressing step in sequence to obtain a methyl epoxide product.
2. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein in the pre-epoxidation step, before the epoxidation reaction, the acid value of the system liquid is 35-70KOHmg/g, the content of hydrogen peroxide in percentage by weight is 3-10%, the use amount of the system liquid is 20-40% of the mass of the fatty acid methyl ester obtained after the pre-treatment, the pre-epoxidation temperature is 60-80 ℃, and the reaction residence time is 5-7 h.
3. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein the system liquid used in the pre-epoxidation step is derived from acidic wastewater obtained by oil-water separation after the completion of the epoxidation step.
4. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein the system liquid used in the pre-epoxidation step is obtained from acidic wastewater obtained by oil-water separation after the completion of the epoxidation step and condensed wastewater at the top of the column in the stripping deacidification step.
5. The continuous production process of epoxidized fatty acid methyl ester according to claim 3 or 4, wherein the acid value of the system liquid is 45-60KOHmg/g, the content of hydrogen peroxide is 4.5-7% by weight, and the use amount of the system liquid is 28-32% of the mass of the fatty acid methyl ester obtained after pretreatment.
6. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein the pretreatment comprises alkali washing and water washing, and the acid value of the pretreated fatty acid methyl ester is less than or equal to 0.3 KOHmg/g.
7. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein the epoxidation reaction is continuously carried out in 5 or more than 5 epoxy reaction kettles arranged in series, the residence time of each kettle is 2-6 h, the temperature is 60-80 ℃, wherein hydrogen peroxide and formic acid are continuously added into the previous 2-4 reaction kettles for 2-4 times respectively, and the weight ratio of the raw materials is as follows: methyl ester: hydrogen peroxide: formic acid 100: 25-35: 3.5-5.5, wherein the concentration of the hydrogen peroxide is 40-60%, and the concentration of the formic acid is 70-90%.
8. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein the material after the epoxy reaction enters a standing tank, the standing time is 1-3 h, standing water separation is performed, and the separated wastewater is used for the pre-epoxy reaction of fatty acid methyl ester.
9. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein one or more deacidification and deacidification towers arranged in series are adopted in the steam stripping and deacidification step, low-pressure steam is adopted in the deacidification and deacidification towers, the steam dosage is 1% -10% of the flow of crude epoxidized fatty acid methyl ester, the epoxidized fatty acid methyl ester temperature is 90-110 ℃, the steam temperature is 120-150 ℃, acidic substances are removed by adopting a vacuum countercurrent contact mode, and the vacuum degree is 0.08-0.1 MPa.
10. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein the vacuum dehydration step is performed in a vacuum dehydration tower at a vacuum degree of 0.09MPa to 0.1MPa and a temperature of < 110 ℃.
11. The continuous production process of epoxidized fatty acid methyl ester according to claim 1, wherein the crude fatty acid methyl ester is C16-C20 fatty acid methyl ester and has an iodine value ranging from 90 to 120. The iodine value of the epoxy fatty acid methyl ester product is less than 5, the acid value is less than 0.5KOHmg/g, and the moisture is less than 0.1%.
12. A continuous production system of epoxidized fatty acid methyl ester is characterized by comprising a pretreatment unit, a pre-epoxidation kettle, an epoxy unit with a plurality of kettles connected in series, a standing tank, a stripping tower, a vacuum dehydration tower and a filter press which are connected in sequence;
the pretreatment unit is used for pretreating a fatty acid methyl ester crude product;
the pre-epoxy kettle is used for pre-epoxy the pretreated fatty acid methyl ester;
the epoxy unit is used for carrying out epoxidation reaction on the pre-epoxidized material;
the standing tank is used for realizing oil-water separation of the materials after the epoxy reaction is finished;
the stripping tower is used for stripping and deacidifying the oil phase separated out from the standing tank;
the vacuum dehydration tower is used for dehydrating the stripped and deacidified epoxy fatty acid methyl ester;
the filter press is used for removing impurities from the dehydrated epoxidized fatty acid methyl ester.
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| CN101070510A (en) * | 2007-05-22 | 2007-11-14 | 李祥庆 | Method for producing epoxy plasticizer using waste grease |
| KR20140096564A (en) * | 2013-01-28 | 2014-08-06 | 동구산업(주) | Improved process for preparing epoxidized fatty acid ester |
| CN107857744A (en) * | 2016-09-22 | 2018-03-30 | 浙江嘉澳环保科技股份有限公司 | A kind of epoxy aliphatic acid methyl ester plasticizer production process and obtained plasticizer |
| CN113929643A (en) * | 2020-07-14 | 2022-01-14 | 浙江嘉澳环保科技股份有限公司 | Continuous production process and system of epoxidized soybean oil |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101070510A (en) * | 2007-05-22 | 2007-11-14 | 李祥庆 | Method for producing epoxy plasticizer using waste grease |
| KR20140096564A (en) * | 2013-01-28 | 2014-08-06 | 동구산업(주) | Improved process for preparing epoxidized fatty acid ester |
| CN107857744A (en) * | 2016-09-22 | 2018-03-30 | 浙江嘉澳环保科技股份有限公司 | A kind of epoxy aliphatic acid methyl ester plasticizer production process and obtained plasticizer |
| CN113929643A (en) * | 2020-07-14 | 2022-01-14 | 浙江嘉澳环保科技股份有限公司 | Continuous production process and system of epoxidized soybean oil |
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