CN114920716B - Continuous production process and system of methyl epoxide - Google Patents
Continuous production process and system of methyl epoxide Download PDFInfo
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- CN114920716B CN114920716B CN202210472731.0A CN202210472731A CN114920716B CN 114920716 B CN114920716 B CN 114920716B CN 202210472731 A CN202210472731 A CN 202210472731A CN 114920716 B CN114920716 B CN 114920716B
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- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000010924 continuous production Methods 0.000 title claims abstract description 23
- -1 methyl epoxide Chemical class 0.000 title description 18
- 239000004593 Epoxy Substances 0.000 claims abstract description 199
- 238000006243 chemical reaction Methods 0.000 claims abstract description 114
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 82
- 235000019387 fatty acid methyl ester Nutrition 0.000 claims abstract description 68
- 150000004702 methyl esters Chemical class 0.000 claims abstract description 57
- 239000000047 product Substances 0.000 claims abstract description 56
- 238000005406 washing Methods 0.000 claims abstract description 56
- 239000002351 wastewater Substances 0.000 claims abstract description 51
- 230000018044 dehydration Effects 0.000 claims abstract description 37
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 37
- 239000002994 raw material Substances 0.000 claims abstract description 31
- 238000000926 separation method Methods 0.000 claims abstract description 22
- 239000012043 crude product Substances 0.000 claims abstract description 8
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 74
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 58
- 239000002253 acid Substances 0.000 claims description 50
- 239000003513 alkali Substances 0.000 claims description 38
- 239000000463 material Substances 0.000 claims description 36
- 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
- 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 29
- 235000019253 formic acid Nutrition 0.000 claims description 29
- 238000006735 epoxidation reaction Methods 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 17
- 239000004927 clay Substances 0.000 claims description 12
- 238000003825 pressing Methods 0.000 claims description 11
- 230000014759 maintenance of location Effects 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- 230000002378 acidificating effect Effects 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 25
- 238000011085 pressure filtration Methods 0.000 abstract description 4
- 238000003908 quality control method Methods 0.000 abstract 1
- 238000004065 wastewater treatment Methods 0.000 abstract 1
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 17
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- 208000005156 Dehydration Diseases 0.000 description 12
- 238000012432 intermediate storage Methods 0.000 description 10
- 235000014113 dietary fatty acids Nutrition 0.000 description 9
- 239000000194 fatty acid Substances 0.000 description 9
- 229930195729 fatty acid Natural products 0.000 description 9
- 150000004665 fatty acids Chemical class 0.000 description 8
- 235000021122 unsaturated fatty acids Nutrition 0.000 description 8
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 6
- 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
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 4
- 239000000920 calcium hydroxide Substances 0.000 description 4
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 4
- 150000004668 long chain fatty acids Chemical class 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
- 238000012797 qualification 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
- 238000005259 measurement Methods 0.000 description 3
- 238000012544 monitoring process Methods 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
- 238000007127 saponification reaction Methods 0.000 description 3
- 235000012424 soybean oil Nutrition 0.000 description 3
- 239000003549 soybean oil Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 235000015112 vegetable and seed oil Nutrition 0.000 description 3
- 239000008158 vegetable oil Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- NWJXSVNLQJZDLV-UHFFFAOYSA-N formic acid;hydrogen peroxide Chemical compound OO.OC=O NWJXSVNLQJZDLV-UHFFFAOYSA-N 0.000 description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 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
- 229910000027 potassium carbonate Inorganic materials 0.000 description 2
- 239000000344 soap Substances 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- 238000003860 storage Methods 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
- 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
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229940109275 cyclamate Drugs 0.000 description 1
- 230000032798 delamination Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000007667 floating Methods 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
- 239000004519 grease Substances 0.000 description 1
- 238000010438 heat treatment 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-L phthalate(2-) Chemical compound [O-]C(=O)C1=CC=CC=C1C([O-])=O XNGIFLGASWRNHJ-UHFFFAOYSA-L 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
- 230000035484 reaction time Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000009897 systematic effect Effects 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
- 238000005809 transesterification reaction Methods 0.000 description 1
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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Epoxy Compounds (AREA)
Abstract
The invention discloses a continuous production process of epoxy fatty acid methyl ester, which comprises the following steps of: the crude product of the fatty acid methyl ester is firstly pretreated, then is subjected to pre-epoxy, then is subjected to epoxy reaction, oil-water separation is carried out after the epoxy reaction is finished, and the oil phase is sequentially subjected to a steam stripping deacidification step, a vacuum dehydration step and a pressure filtration step to obtain the product of the epoxy methyl ester. The invention realizes the full-flow automation and the serialization 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 quality control is carried out on the raw materials, 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, the method is 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 technological method and a system for continuous production and post-treatment of methyl epoxide.
Background
The methyl epoxide is a nontoxic non-benzene environment-friendly plastic plasticizer which is widely applied at present, has the dual 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 protection consciousness of various countries in the world, the toxicity of the plasticizer is more and more concerned by people; plasticizer phthalate products are suspected of being carcinogenic, and many developed countries have prohibited their use in plastic products such as medical and food packaging, commodity products, toys, and the like. And because of tight petroleum supply, the market price of the international and domestic plasticizer is increased, and the raw materials mainly used by the methyl oxide are renewable resources, the product has wide market prospect.
At present, the domestic production of the methyl oxide is carried out by using an intermittent production process, carrying out epoxy reaction through a kettle type stirring reactor, carrying out water separation treatment through a water separation tank or a centrifugal machine, carrying out alkali washing after water separation, washing with water, and finally carrying out dehydration treatment to obtain a finished product of the methyl oxide, wherein the alkali washing is adopted to reduce acid to cause saponification phenomenon, which is not beneficial to water separation, reduces the product yield, simultaneously introduces impurities such as sodium ions and the like, reduces the volume resistivity, and the sodium ions and grease form soap in the methyl oxide, so that the impurities in the methyl oxide are increased, and the indexes such as flash point, product yield, volume resistivity and the like are influenced. The prior art adopts an intermittent method to prepare the methyl epoxy ester, the product quality is greatly influenced by manual operation, the product quality is not easy to control, the unit productivity energy consumption 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 reaction heating is large in the process of adding hydrogen peroxide and formic acid, the heat exchange capacity of the reactor is limited, the epoxy reaction is required to be slowly added for a plurality of times, the temperature of the epoxy reaction is required to be strictly controlled, and the epoxy reaction is particularly produced in summer, is difficult to control the temperature, is easy to exceed the temperature, affects the product quality, and can cause safety accidents such as material spraying of a reaction kettle and the like when the epoxy reaction is serious.
Patent document with publication number of CN113929643A discloses a continuous production process and system of epoxidized soybean oil, comprising an epoxidation step, a water diversion treatment step, a deacidification treatment step and a dehydration treatment step which are sequentially carried out, wherein the epoxidation step is continuously carried out in two or more epoxy reaction kettles which are arranged in series; and (3) carrying out continuous water separation treatment on the material subjected to epoxidation treatment through an overflow tank, after water separation, entering a stripping tower for continuous deacidification treatment, after the acid value reaches the standard, entering a vacuum dehydration tower for continuous dehydration treatment, and finally, carrying out filter pressing to obtain an epoxidized soybean oil finished product. The document solves the problems of the prior art to a certain extent by adopting a multi-kettle serial connection mode for 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 personnel and energy consumption, improve the quality of a methyl cyclamate product and improve the yield of the product in order to improve the product quality, optimize the production process and reduce the production cost.
The continuous production process of the epoxy fatty acid methyl ester comprises the steps of raw material pretreatment, pre-epoxy, epoxy reaction, standing water diversion, steam stripping deacidification, vacuum dehydration, filter pressing of products and the like which are sequentially carried out, and concretely comprises the following steps of continuously carrying out: the crude product of the fatty acid methyl ester is firstly pretreated, then is subjected to pre-epoxy, then is subjected to epoxy reaction, oil-water separation is carried out after the epoxy reaction is finished, and the oil phase is sequentially subjected to a steam stripping deacidification step, a vacuum dehydration step and a pressure filtration step to obtain the product of the epoxy methyl ester.
In the pretreatment step, the pretreatment mainly comprises the step of removing glycerol, glyceride, fatty acid and the like in the crude fatty acid methyl ester. Preferably, the pretreatment is alkali washing and water washing, and the glycerol, 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 0.3KOHmg/g. The fatty acid methyl ester raw material has larger floating of product index compared with soybean oil, and the stability of the production device can be improved by preprocessing the epoxy. Furthermore, by adopting the technical scheme, the quality of the product can be effectively ensured for special raw materials such as waste animal and vegetable oil. The crude fatty acid methyl ester is generally obtained by transesterification and rectification of waste animal and vegetable oil, and because of the complexity and fluctuation of waste animal and vegetable oil components, the content fluctuation of substances such as glycerol, glyceride, fatty acid and the like in the crude fatty acid methyl ester is large, even if the same batch of products are in different stages of rectification, the content of substances such as glycerol, glyceride, fatty acid and the like in the obtained products is different, the fluctuation of acid value is large, and the quality of the products is difficult to ensure when continuous production is carried out; the invention can unify standards by utilizing pretreatment.
In the pre-epoxidation step, the pretreated fatty acid methyl ester raw material and system liquid (mainly composed of formic acid, hydrogen peroxide and water) are subjected to pre-epoxidation reaction. Preferably, the acid value of the pre-epoxy system liquid is 35-70KOHmg/g, the weight percentage content of hydrogen peroxide is 3-10%, and the dosage 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 to 80 ℃ (more preferably 70 to 80 ℃), and the reaction residence time is 5 to 7 hours.
The pre-epoxy can be performed by adopting a pure reagent, namely, the pre-epoxy is performed by adding hydrogen peroxide, formic acid, water and the like. Recovered spent acid may also be used. More preferably, the pre-epoxy system liquid is derived from acid 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 liquid can be further recovered, the COD value of the final wastewater can be further reduced while the utilization rate of raw materials is improved, the biochemical treatment is easy, and the reaction temperature and the material consumption of the subsequent epoxy reaction can be reduced.
Preferably, the pre-epoxy system liquid is from acid wastewater obtained by oil-water separation after the epoxy reaction, and the condensed wastewater at the top of the stripping deacidification tower. By adopting the technical scheme, the utilization rate of raw materials is further improved. Meanwhile, COD sources in the wastewater mainly comprise formic acid, hydrogen peroxide, dissolved epoxy fatty acid methyl ester, saponified epoxy fatty acid methyl ester and the like, the amount of the formic acid and the hydrogen peroxide can be reduced by re-epoxy of the wastewater, and the saponification of the epoxy fatty acid methyl ester and the dissolution of the epoxy fatty acid methyl ester can be further avoided by matching with the stripping operation. From the source, the generation of COD source is reduced.
As a further preference, the acid value of the system liquid is 45-60KOHmg/g, the weight percentage content of hydrogen peroxide is 4.5-7%, and the system liquid dosage is 28-32% of the mass of the fatty acid methyl ester obtained after pretreatment.
After the pre-oxidation is completed, the feeding ratio of hydrogen peroxide and formic acid in the epoxidation reaction is determined by detecting the iodine value and the like of the pre-epoxy product in a test stage or before production.
Preferably, the epoxy reaction is continuously carried out in 5 or more epoxy reaction kettles arranged in series, the residence time of each kettle is 2-5 h, the temperature is 60-80 ℃, hydrogen peroxide and formic acid are respectively and continuously added into the previous 2-4 reaction kettles (for example, the materials are equally divided into n parts and then respectively and continuously added into the previous n epoxy reaction kettles 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 to 5.5, wherein the concentration of hydrogen peroxide is 40 to 60 percent and the concentration of formic acid is 70 to 90 percent.
Preferably, the material after the epoxy reaction is finished enters a standing tank, the retention time is 1-3 h, standing and water separation are carried out, and the waste water is separated for the pre-epoxy reaction of fatty acid methyl ester.
Preferably, in the step of stripping and deacidifying, one or more deacidification stripping towers which are arranged in series are adopted, low-pressure steam is adopted in the deacidification stripping towers, the steam consumption is 1% -10% (more preferably 1% -5%) of the flow of the crude product of the epoxy fatty acid methyl ester, the temperature of the stripped epoxy fatty acid methyl ester is 90-110 ℃, the 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 carried out in a vacuum dehydration tower, the vacuum degree is 0.09 MPa-0.1 MPa, and the temperature is less than 110 ℃.
Preferably, in the pressure filtration step, clay or diatomite is used to remove insoluble impurities contained in the epoxy fatty acid methyl ester.
Preferably, the crude fatty acid methyl ester is C16-C20 fatty acid methyl ester, and the iodine value is in the range of 90-120.
Preferably, the iodine value of the methyl epoxide product is less than 5, the acid value is less than 0.5KOHmg/g, and the water content is less than 0.1%.
Preferably, a continuous production process of methyl epoxy ester comprises the following steps:
(1) The method comprises the steps of (1) pre-treating and removing substances such as glycerol, glyceride, fatty acid and the like contained in raw methyl ester (the raw methyl ester refers to fatty acid methyl ester) through alkali washing and water washing;
(2) Pre-epoxy is carried out on the pretreated raw material methyl ester and the wastewater obtained by standing separation, and formic acid and hydrogen peroxide contained in the wastewater are reused;
(3) After the pre-epoxy methyl ester is subjected to water diversion, epoxy reaction is carried out, 5 or more epoxy reaction kettles are arranged in series and are continuously carried out, the residence time of each kettle is 2-5 h, the temperature is 60-80 ℃, hydrogen peroxide and formic acid are respectively and continuously dripped into the reaction kettles for 2-4 times, and the weight ratio of raw materials is as follows: methyl ester: hydrogen peroxide: formic acid=100: 25-35: 3.5 to 5.5, wherein the concentration of hydrogen peroxide is 40 to 60 percent and the concentration of formic acid is 70 to 90 percent.
(4) Standing and water diversion is carried out after the epoxy is finished, the residence time is 1-3 h, and the waste water is separated according to liquid level conversion and is used for the pre-epoxy reaction of methyl ester; the separated crude product of the methyl epoxide enters the next working procedure;
(5) The crude product of the methyl epoxide is subjected to steam stripping deacidification by adopting one or more deacidification stripping towers which are arranged in series, the deacidification stripping towers adopt low-pressure steam, the steam temperature is 120-150 ℃, the steam consumption is about 1-10% 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) Vacuum dehydration is carried out after the stripping is completed, the vacuum degree is 0.09MPa to 0.1MPa, the temperature of the dehydration tower is less than 110 ℃ (more preferably 80 to 110 ℃). And then the product is obtained through filter pressing.
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 feed liquid occupies 1/2-4/5 of the internal volume of the epoxy reaction kettle. And, each epoxy reaction kettle is provided with a matched stirring device so as to ensure the stability and the rapid reaction of materials.
Preferably, the total residence time in the epoxidation step is from 15 to 20 hours.
Preferably, when the quality index of the final discharged material does not meet the requirement, the final material can be ensured to meet the final quality requirement by increasing the number of epoxy reaction kettles or by increasing the reaction time or supplementing materials and the like. The final volume of the epoxy reaction kettle can be properly reduced to further improve the utilization rate of the device, for example, the final end reaction kettle with the volume of about 1/4-1/2 of the final epoxy reaction kettle can be added at the discharge port of the final epoxy reaction kettle.
Preferably, 3-7 epoxy reaction kettles (preferably 5-6 epoxy reaction kettles) connected in series are adopted for the epoxidation reaction, wherein the temperature of the epoxy reaction kettles, to which hydrogen peroxide and formic acid are added dropwise, is controlled to be 60-70 ℃, the residence time of each epoxy reaction kettle is 2-6 hours (further preferably 3-5 hours), the temperature of the heat-preserving reaction kettles (without hydrogen peroxide and formic acid) is controlled to be 75-80 ℃, and the residence time of each epoxy reaction kettle is controlled to be 2-6 hours (further preferably 3-5 hours).
Preferably, the deacidification step is carried out by adopting one or more deacidification stripping towers which are arranged in series, the deacidification stripping towers adopt superheated low-pressure steam, the steam temperature is 120-150 ℃, the 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 at regular 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 the moisture content of the material is 0.02-0.05% after the dehydration step is completed.
After the epoxidation reaction, the iodine value of the product is less than 5.
A continuous production system of epoxy 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 the crude fatty acid methyl ester;
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-epoxy 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 carrying out stripping deacidification on the oil phase separated 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 dehydrated epoxy fatty acid methyl ester.
Preferably, the acid waste water outlet of the standing tank is connected with an intermediate storage tank; the 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 column is connected to a condensing heat exchanger, the condensate outlet of which is simultaneously connected to the intermediate storage tank.
Preferably, the stripper product outlet is connected to an intermediate product tank, and the product tank outlet is connected to the filter press inlet. By utilizing the technical scheme, on one hand, the collection of the stripping tower products is realized, and meanwhile, the monitoring of the acid value of the products is also facilitated. When the acid value is monitored according to the set time interval, if the acid value is not satisfactory, solid alkali (namely clay or diatomite and alkaline clay with the volume of 10:0.5-2) can be added into the filter press to remove the free fatty acid.
Preferably, the pretreatment unit comprises an alkaline washing tank and a water washing tank, one or two static tanks are arranged at the same time, the alkaline washing tank is firstly mixed with alkaline liquor in a stirring manner, the concentration of the 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 alkaline is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate and is added in the form of aqueous solution. The retention time of alkaline washing is 20-60 min, the alkaline washing discharging material enters a standing tank, the retention time of the standing tank is 1-3 h, methyl ester enters a water washing tank after standing and water diversion, the water consumption is 2-5% of the methyl ester flow, the water washing retention time is 20-60 min, the water washing discharging material enters the standing tank, and the retention 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 requirements on production equipment and easy industrialized production, and the flow chart is shown in figure 1.
To further embody the advantages of the present invention, a comparison of the advantages of the present invention with those of the prior art will be described:
firstly, raw material methyl ester (fatty acid methyl ester) pretreatment can ensure the stability of raw material indexes, and can reduce the content of glycerin, glyceride and fatty acid to reduce epoxy side reaction, wherein the reduction of the content of monoglyceride can improve the oil-water delamination efficiency, and the reduction of the content of fatty acid can reduce the acid value of the product. Compared with the prior art, the production stability can be ensured, and the problems of exceeding acid value, difficult separation of waste water and the like are avoided.
And (II) pre-epoxidation, wherein residual formic acid and hydrogen peroxide in the epoxy wastewater are utilized for pre-epoxidation reaction, so that raw materials of formic acid and hydrogen peroxide in the wastewater can be fully utilized, the iodine value of methyl ester after pre-epoxidation is reduced, the consumption of the formic acid and the hydrogen peroxide in the epoxy reaction stage can be reduced, and compared with the prior art, the consumption of the formic acid and the hydrogen peroxide can be reduced by 5% -10%.
And thirdly, the continuous multi-kettle serial connection is adopted to optimize the configuration of the epoxy reaction kettle, 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 the deep epoxy can be realized in the heat-insulating epoxy reaction kettle because the reaction heat is smaller. The reaction temperature, the heat release amount and the material state of each reaction kettle are relatively high, and the production control is relatively simple. When the traditional intermittent production is adopted, the hydrogen peroxide formic acid cannot be normally added for reaction due to the limitation of heat exchange capacity in the production process, and the hydrogen peroxide formic acid needs to be added for multiple times, so that the reaction temperature is ensured not to exceed the temperature.
(IV) stripping and deacidifying to improve the product quality: no new impurities are introduced, the flash point is increased, and the smell is reduced; the product yield is improved: less ineffective saponification in the alkaline washing process, and reduced loss caused by product dissolution in the alkaline washing and water washing processes; the generation of waste water is reduced: avoiding soap-containing wastewater generated in the alkaline washing and water washing processes; raw material recovery: the formic acid contained in the crude methyl oxide can be recycled;
and (V) monitoring the quality index of continuous production: according to the invention, a multi-kettle serial reaction is adopted, 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 suitably shortened, and the device for supplementing hydrogen peroxide is arranged, so that the standard of products can be assisted, and the previous reaction and the addition of raw materials are not influenced. When the acid value of the vacuum deacidification does not reach the standard, secondary deacidification/tertiary deacidification can be set, and the material is discharged after reaching the standard. If abnormal conditions still occur and the acid value cannot be reduced, alkali can be properly added for deacidification in the filter pressing process. Therefore, the device provided by the invention has stronger adjustability and adaptability, and is more beneficial to control over the quality of the final product.
In the conventional intermittent production process, the post-treatment process has high labor intensity, water needs to be separated for many times, water separation operation is greatly influenced by human factors, a part of products are put into waste water to generate loss, and in addition, in the process of adding alkali liquor, the excessive degree is different, so that the loss is also high. The continuous production process does not need direct operation of personnel, after each process index is set, only the product index is measured, and if the product index is up to standard, the product index is subjected to secondary treatment according to the related operation flow which is up to 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, low requirements on production equipment and easy industrialized production.
Drawings
FIG. 1 is a schematic and systematic diagram of a process flow employed in an embodiment of the present invention.
Detailed Description
In order to make the technical scheme of the invention more clear and clear, the invention is further described below with reference to the accompanying drawings and examples:
FIG. 1 is a process flow partially adopted in the embodiment of the invention, and is a continuous production process of epoxy fatty acid methyl ester, which comprises the steps of raw material pretreatment, pre-epoxy, epoxy reaction, standing water diversion, stripping deacidification, vacuum dehydration, pressure filtration and the like, so as to obtain a finished product of epoxy methyl ester (methyl ester of epoxy fatty acid).
As shown in figure 1, the continuous production system of the epoxy 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 the crude fatty acid methyl ester; the pretreatment unit comprises an alkaline washing tank and a water washing tank, an intermediate standing tank is arranged between the alkaline washing tank and the water washing tank, a standing tank is arranged behind the water washing tank, the alkaline washing tank and the water washing tank are respectively provided with a crude fatty acid methyl ester inlet, an alkali liquor/water washing inlet, a waste water outlet and a material outlet, and each inlet is respectively connected with the crude fatty acid methyl ester raw material tank, the alkali 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 middle 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. The 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. The material outlet of the pre-epoxy kettle is connected with the feeding hole of the epoxy unit.
The epoxy unit is used for carrying out epoxidation reaction on the pre-epoxy material; the epoxy unit is composed of 5 or more epoxy reaction kettles arranged in series. And introducing the reaction liquid of the epoxy unit into a standing tank to finish standing and water separation.
The standing tank is used for realizing oil-water separation of the materials after the epoxy reaction is finished; the acid wastewater outlet is collected in the middle storage tank in a concentrated way for the pre-epoxy unit.
The stripping tower is used for stripping and deacidifying the oil phase separated from the standing tank. The stripping wastewater can also be simultaneously introduced into the intermediate storage tank for the pre-epoxidation reaction.
The vacuum dehydration tower is used for dehydrating the epoxy fatty acid methyl ester after the steam stripping deacidification;
the filter press is used for removing impurities from the dehydrated epoxy fatty acid methyl ester.
The process is further described below:
pretreatment of raw materials: the raw material methyl ester (namely unsaturated long-chain fatty acid methyl ester with the iodine value of 90-120, mainly comprising C16-C20 unsaturated fatty acid methyl ester, 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 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 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 retention time of alkaline washing is 20-60 min, the alkaline washing is discharged and then enters a standing tank, the retention time of the standing tank is 1-3 h, methyl ester enters a water washing tank after standing and water diversion, the water consumption is 2-5% of the methyl ester flow, the water washing retention time is 20-60 min, the water washing is discharged and enters the standing tank, the retention time of the standing tank is 1-3 h, the pretreatment of discharged material is completed after standing, and pretreated wastewater goes to a wastewater treatment center.
(1) Pre-epoxy: and (3) after pretreatment, methyl ester (fatty acid methyl ester) enters a pre-epoxy kettle, and is mixed and stirred with separated acid wastewater after the epoxy reaction, and the condensed wastewater at the top of the stripping tower (the acid value of the wastewater is about 45-60KOHmg/g, the hydrogen peroxide content is 4.5-7%, and the wastewater amount is about 28-32% of the mass of methyl ester) to perform the pre-epoxy reaction. The pre-epoxy temperature is 60-80 ℃, and the reaction residence time is 5-7 h.
(2) Epoxy reaction: the epoxy reaction is carried out by serially connecting 5-7 kettles, formic acid and hydrogen peroxide are uniformly added in three-four kettles according to the proportion for 3-4 times, the reaction temperature of the three-four kettles is controlled at 60-65 ℃, the residence time is 3-5 h, the reaction temperature of the fourth-five kettles or the fifth-six kettles is controlled at 75-80 ℃, the residence time is 3-5 h, the iodine value is measured after the fifth or six kettles are discharged, the iodine value is required to be less than 5, if the problem of higher iodine value occurs, the reaction residence time of the fifth or six kettles can be increased, and the index qualification is ensured. And after the epoxy is finished, the epoxy enters a standing tank for water diversion, and crude methyl epoxide is obtained.
(3) Stripping and deacidifying: the crude epoxy methyl ester after the epoxy is separated is preheated to 90-120 ℃, enters a stripping tower, the vacuum degree of the stripping tower is controlled to be minus 0.08-minus 0.1MPa, the tower temperature is controlled to be 80-110 ℃, the steam consumption is 1-5% of the feeding flow of the crude epoxy methyl ester, the crude epoxy methyl ester enters an intermediate storage tank after discharged from the tower bottom, and the acid value is monitored 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 minus 0.9-minus 0.1MPa, the water content at the outlet is controlled to be less than or equal to 0.1%, the product is filtered out after dehydration, and when the stripping acid value is more than 0.5, part of solid alkali (such as alkaline clay of clay and calcium hydroxide 10:1) can be added into a filter press for adsorbing redundant acidic substances.
Example 1:
pretreatment of raw materials: the raw material methyl ester (namely unsaturated long-chain fatty acid methyl ester with iodine value of 110, mainly containing C16-C20 unsaturated fatty acid methyl ester and taking C18 unsaturated fatty acid methyl ester as main components) is fed through a metering pump, enters a pretreatment unit, is stirred and mixed with alkali liquor in an alkali washing tank, wherein the concentration of the alkali liquor is 2% wt, the flow rate of the alkali liquor is 4% of the flow rate of methyl ester, and the alkali is sodium hydroxide aqueous solution. The alkali washing residence time is 40min, the alkali washing discharged material enters an intermediate standing tank, the residence time of the intermediate standing tank is 2h, methyl ester enters a water washing tank after standing and water separation, the water consumption is 4% of the methyl ester flow, 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 discharged material is pretreated after standing, and pretreated wastewater goes to a wastewater treatment center.
(1) Pre-epoxy: and (3) after pretreatment, methyl ester (fatty acid methyl ester) enters a pre-epoxy kettle, and is mixed and stirred with separated acid wastewater after the epoxy reaction, and the condensed wastewater at the top of the stripping tower (the acid value of the wastewater is about 50KOHmg/g, the hydrogen peroxide content is 6%, and the wastewater amount is about 30% of the mass of the methyl ester) to perform the pre-epoxy reaction. The pre-epoxy temperature was 70℃and the reaction residence time was 5h.
(2) Epoxy reaction: through serial epoxy reaction of 6 kettles, formic acid and hydrogen peroxide are added dropwise in the first 4 kettles uniformly 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 3h, the reaction temperature of the fifth kettle and the sixth kettle is controlled to be 75-80 ℃, the residence time is controlled to be 3h, the iodine value is measured after the discharge of the sixth kettle, the iodine value is required to be less than 5, if the problem of higher iodine value occurs, the reaction residence time of the sixth kettle can be increased, and the qualification of indexes is ensured. And after the epoxy is finished, the epoxy enters a standing tank for water diversion, and crude methyl epoxide is obtained.
(3) Stripping and deacidifying: the crude epoxy methyl ester after the epoxy is subjected to water diversion is preheated to 100 ℃, enters a stripping tower, the vacuum degree of the stripping tower is controlled at-0.09 MPa, the tower temperature is controlled at 90 ℃, the steam consumption is 3% of the feeding flow of the crude epoxy methyl ester, the crude epoxy methyl ester enters an intermediate storage tank after discharged from the tower bottom, and the acid value is monitored 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 minus 0.9MPa, the water content at the outlet is controlled to be less than or equal to 0.1 percent, the product is filtered out after dehydration, and when the stripping acid value is more than 0.5, part of solid alkali (such as alkaline clay of clay and calcium hydroxide 10:1) can be added into a filter press for adsorbing redundant acidic substances. Product performance test data are shown in the following table:
| project | Measurement value | Standard value |
| Acid value KOHmg/g | 0.36 | ≤0.5 |
| Iodine value I 2 g/100g | 4.1 | ≤5 |
| Moisture% | 0.06 | ≤0.1 |
| Color Pt-CO | 60 | ≤80 |
| Epoxy value g/100g | 5.45 | ≥5.2 |
Note that: raw materials with different iodine values, and products with different epoxy value requirements
Example 2:
pretreatment of raw materials: the raw material methyl ester (namely unsaturated long-chain fatty acid methyl ester with the iodine value of 100, mainly comprising C16-C20 unsaturated fatty acid methyl ester and taking C18 unsaturated fatty acid methyl ester as main components) is fed through a metering pump, enters a pretreatment unit, is stirred and mixed with alkali liquor, the concentration of the alkali liquor is 2% wt, the flow rate of the alkali liquor is 4% of the flow rate of the methyl ester, and the alkali is sodium hydroxide aqueous solution. The alkali washing residence time is 40min, the alkali washing discharged material enters a standing tank, the residence time of the standing tank is 2h, methyl ester enters a water washing tank after standing and water diversion, the water consumption is 4% of the methyl ester flow, 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 discharged material is pretreated after standing, and pretreated wastewater goes to a wastewater treatment center.
(1) Pre-epoxy: and (3) after pretreatment, methyl ester (fatty acid methyl ester) enters a pre-epoxy kettle, and is mixed and stirred with separated acid wastewater after the epoxy reaction, and the condensed wastewater at the top of the stripping tower (the acid value of the wastewater is about 48KOHmg/g, the hydrogen peroxide content is 5.5%, and the wastewater content is about 28% of the mass of methyl ester) to perform pre-epoxy reaction. The pre-epoxy temperature was 75℃and the reaction residence time was 5h.
(2) Epoxy reaction: through serial epoxy reaction of 5 kettles, formic acid and hydrogen peroxide are added dropwise into the first three kettles uniformly 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 controlled to be 4 hours respectively, the reaction temperature of the fourth kettle and the fifth kettle is controlled to be 75-80 ℃, the residence time is controlled to be 3 hours respectively, the iodine value is measured after the discharge of the fifth kettle, the iodine value is required to be less than 5, if the problem of higher iodine value occurs, the reaction residence time of the fifth kettle can be increased, and the qualification of indexes is ensured. And after the epoxy is finished, the epoxy enters a standing tank for water diversion, and crude methyl epoxide is obtained.
(3) Stripping and deacidifying: the crude epoxy methyl ester after the epoxy is subjected to water diversion is preheated to 110 ℃, enters a stripping tower, the vacuum degree of the stripping tower is controlled at-0.092 MPa, the tower temperature is controlled at 93 ℃, the steam consumption is 2% of the feeding flow of the crude epoxy methyl ester, the crude epoxy methyl ester enters an intermediate storage tank after discharged from the tower bottom, and the acid value is monitored 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 minus 0.9MPa, the water content at the outlet is controlled to be less than or equal to 0.1 percent, the product is filtered out after dehydration, and when the stripping acid value is more than 0.5, part of solid alkali (such as alkaline clay of clay and calcium hydroxide 10:1) can be added into a filter press for adsorbing redundant acidic substances. Product performance test data are shown in the following table:
| project | Measurement value | Standard value |
| Acid value KOHmg/g | 0.32 | ≤0.5 |
| Iodine value I 2 g/100g | 3.9 | ≤5 |
| Moisture% | 0.07 | ≤0.1 |
| Color Pt-CO | 60 | ≤80 |
| Epoxy value g/100g | 5.05 | ≥4.8 |
Note that: the epoxy value of the product is different from the iodine value raw material.
Example 3:
pretreatment of raw materials: the raw material methyl ester (namely unsaturated long-chain fatty acid methyl ester with an iodine value of 90, mainly comprising C16-C20 unsaturated fatty acid methyl ester and taking C18 unsaturated fatty acid methyl ester as main components) is fed through a metering pump, enters a pretreatment unit, is stirred and mixed with alkali liquor, the concentration of the alkali liquor is 2% wt, the flow rate of the alkali liquor is 4% of the flow rate of the methyl ester, and the alkali is sodium hydroxide aqueous solution. The alkali washing residence time is 40min, the alkali washing discharged material enters a standing tank, the residence time of the standing tank is 2h, methyl ester enters a water washing tank after standing and water diversion, the water consumption is 4% of the methyl ester flow, 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 discharged material is pretreated after standing, and pretreated wastewater goes to a wastewater treatment center.
(1) Pre-epoxy: and (3) after pretreatment, methyl ester (fatty acid methyl ester) enters a pre-epoxy kettle, and is mixed and stirred with separated acid wastewater after the epoxy reaction, and the condensed wastewater at the top of the stripping tower (the acid value of the wastewater is about 45KOHmg/g, the hydrogen peroxide content is 4.3%, and the wastewater content is about 26% of the mass of methyl ester) to perform pre-epoxy reaction. The pre-epoxy temperature was 80℃and the reaction residence time was 5h.
(2) Epoxy reaction: through serial epoxy reaction of 4 kettles, formic acid and hydrogen peroxide are added dropwise in the first two kettles for 2 times according to the proportion, the reaction temperature of the first two kettles is controlled at 60-65 ℃, the residence time is controlled at 75-80 ℃ respectively, the residence time is 3h respectively, the iodine value is measured after the fourth kettle is discharged, the iodine value is required to be less than 5, if the problem of higher iodine value occurs, the reaction residence time of the fourth kettle can be increased, and the qualification of indexes is ensured. And after the epoxy is finished, the epoxy enters a standing tank for water diversion, and crude methyl epoxide is obtained.
(3) Stripping and deacidifying: the crude epoxy methyl ester after the epoxy is completely separated is preheated to 120 ℃, enters a stripping tower, the vacuum degree of the stripping tower is controlled at-0.095 MPa, the tower temperature is controlled at 95 ℃, the steam consumption is 1% of the feeding flow of the crude epoxy methyl ester, the crude epoxy methyl ester enters an intermediate storage tank after discharged from the tower bottom, and the acid value is monitored 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 minus 0.9MPa, the water content at the outlet is controlled to be less than or equal to 0.1 percent, the product is filtered out after dehydration, and when the stripping acid value is more than 0.5, part of solid alkali (such as alkaline clay of clay and calcium hydroxide 10:1) can be added into a filter press for adsorbing redundant acidic substances. Product performance test data are shown in the following table:
| project | Measurement value | Standard value |
| Acid value KOHmg/g | 0.34 | ≤0.5 |
| Iodine value I 2 g/100g | 4.3 | ≤5 |
| Moisture% | 0.06 | ≤0.1 |
| ColorPt-CO | 60 | ≤80 |
| Epoxy value g/100g | 4.65 | ≥4.5 |
Note that: the epoxy value of the product is different from the iodine value raw material.
Compared to the prior art process (without pre-oxidation step, single pot batch reaction for the epoxidation step and alkaline and water washing steps for the stripping of the carboxylic acid), the process of example 1 was used to produce 1 ton of methyl epoxide fatty acid ester, with the following results:
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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 can effectively reduce the waste water amount and the COD content in the waste water.
Claims (6)
1. The continuous production process of the epoxy fatty acid methyl ester is characterized by comprising the following steps of: firstly, pretreating a crude product of fatty acid methyl ester, then, pre-epoxy, then, performing an epoxy reaction, performing oil-water separation after the epoxy reaction is finished, and sequentially performing a steam stripping deacidification step, a vacuum dehydration step and a filter pressing step on an oil phase to obtain an epoxy methyl ester product;
the system liquid adopted in the pre-epoxy step is from acid wastewater obtained by oil-water separation after the epoxy reaction step is finished;
in the pre-epoxy step, before the epoxy reaction, the acid value of the system liquid is 35-70KOHmg/g, the weight percentage content of hydrogen peroxide is 3-10%, the dosage of the system liquid is 20-40% of the mass of fatty acid methyl ester obtained after the pretreatment, the pre-epoxy temperature is 60-80 ℃, and the reaction residence time is 5-7 h;
the epoxy reaction is continuously carried out in 5 or more epoxy reaction kettles which are 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 respectively and continuously added into the previous 2-4 reaction kettles for 2-4 times, and the weight ratio of the raw materials is as follows: methyl ester: hydrogen peroxide: formic acid=100: 25-35: 3.5 to 5.5, wherein the concentration of hydrogen peroxide is 40 to 60 percent and the concentration of formic acid is 70 to 90 percent;
the material after the epoxy reaction enters a standing tank, the retention time is 1-3 h, standing and water diversion are carried out, and the separated wastewater is used for the pre-epoxy reaction of fatty acid methyl ester;
in the steam stripping deacidification step, one or more deacidification stripping towers which are arranged in series are adopted, low-pressure steam is adopted in the deacidification stripping towers, the steam consumption is 1% -10% of the flow of the crude product of the epoxy fatty acid methyl ester, the temperature of the epoxy fatty acid methyl ester 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;
the vacuum dehydration step is carried out in a vacuum dehydration tower, the vacuum degree is 0.09 MPa-0.1 MPa, and the temperature is less than 110 ℃;
in the filter pressing step, clay or diatomite is adopted to remove insoluble impurities contained in the epoxy fatty acid methyl ester.
2. 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 reaction step and overhead condensed wastewater in the stripping deacidification step.
3. The continuous production process of epoxy fatty acid methyl ester according to claim 1 or 2, wherein the acid value of the system liquid is 45-60KOHmg/g, the hydrogen peroxide weight percentage content is 4.5-7%, and the system liquid consumption is 28-32% of the mass of the fatty acid methyl ester obtained after pretreatment.
4. The continuous production process of epoxy fatty acid methyl ester according to claim 1, wherein the pretreatment is alkali washing and water washing, and the acid value of the pretreated fatty acid methyl ester is less than or equal to
0.3KOHmg/g。
5. The continuous production process of epoxy fatty acid methyl ester according to claim 1, wherein the crude fatty acid methyl ester is C16-C20 fatty acid methyl ester with 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 water content is less than 0.1%.
6. A continuous production system of epoxy fatty acid methyl ester for implementing the process of any one of claims 1 to 5, which is characterized by comprising a pretreatment unit, a pre-epoxy kettle, an epoxy unit with multiple 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 the crude fatty acid methyl ester;
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-epoxy 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 carrying out stripping deacidification on the oil phase separated 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 dehydrated epoxy 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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