CN115286486A - Method for removing azeotropic substances in recovered methanol - Google Patents
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- CN115286486A CN115286486A CN202211025685.6A CN202211025685A CN115286486A CN 115286486 A CN115286486 A CN 115286486A CN 202211025685 A CN202211025685 A CN 202211025685A CN 115286486 A CN115286486 A CN 115286486A
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- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 title claims abstract description 234
- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000000126 substance Substances 0.000 title claims description 4
- OWXJKYNZGFSVRC-NSCUHMNNSA-N (e)-1-chloroprop-1-ene Chemical compound C\C=C\Cl OWXJKYNZGFSVRC-NSCUHMNNSA-N 0.000 claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000012320 chlorinating reagent Substances 0.000 claims abstract description 9
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 238000006243 chemical reaction Methods 0.000 claims description 34
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 30
- 239000007789 gas Substances 0.000 claims description 22
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 18
- 239000012295 chemical reaction liquid Substances 0.000 claims description 14
- 238000005660 chlorination reaction Methods 0.000 claims description 12
- 238000005086 pumping Methods 0.000 claims description 12
- 238000010992 reflux Methods 0.000 claims description 12
- LRWZZZWJMFNZIK-UHFFFAOYSA-N 2-chloro-3-methyloxirane Chemical compound CC1OC1Cl LRWZZZWJMFNZIK-UHFFFAOYSA-N 0.000 claims description 8
- YGYAWVDWMABLBF-UHFFFAOYSA-N Phosgene Chemical compound ClC(Cl)=O YGYAWVDWMABLBF-UHFFFAOYSA-N 0.000 claims description 8
- FYSNRJHAOHDILO-UHFFFAOYSA-N thionyl chloride Chemical compound ClS(Cl)=O FYSNRJHAOHDILO-UHFFFAOYSA-N 0.000 claims description 8
- 239000008346 aqueous phase Substances 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- XMJHPCRAQCTCFT-UHFFFAOYSA-N methyl chloroformate Chemical compound COC(Cl)=O XMJHPCRAQCTCFT-UHFFFAOYSA-N 0.000 claims description 4
- 238000011084 recovery Methods 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 2
- 239000003518 caustics Substances 0.000 claims 1
- 239000000463 material Substances 0.000 claims 1
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 abstract description 44
- LKMJVFRMDSNFRT-UHFFFAOYSA-N 2-(methoxymethyl)oxirane Chemical compound COCC1CO1 LKMJVFRMDSNFRT-UHFFFAOYSA-N 0.000 abstract description 3
- 238000004064 recycling Methods 0.000 abstract 1
- 238000010521 absorption reaction Methods 0.000 description 17
- 238000005406 washing Methods 0.000 description 16
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 15
- 239000002994 raw material Substances 0.000 description 10
- 239000012071 phase Substances 0.000 description 9
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 8
- 238000006735 epoxidation reaction Methods 0.000 description 8
- 125000004122 cyclic group Chemical group 0.000 description 7
- 238000003860 storage Methods 0.000 description 5
- 238000009835 boiling Methods 0.000 description 4
- 239000003513 alkali Substances 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- XENVCRGQTABGKY-ZHACJKMWSA-N chlorohydrin Chemical compound CC#CC#CC#CC#C\C=C\C(Cl)CO XENVCRGQTABGKY-ZHACJKMWSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- UGACIEPFGXRWCH-UHFFFAOYSA-N [Si].[Ti] Chemical compound [Si].[Ti] UGACIEPFGXRWCH-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 229920005558 epichlorohydrin rubber Polymers 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- -1 on one hand Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007127 saponification reaction Methods 0.000 description 1
- 238000013341 scale-up Methods 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
- C07C17/16—Preparation of halogenated hydrocarbons by replacement by halogens of hydroxyl groups
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
- C07C17/383—Separation; Purification; Stabilisation; Use of additives by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/88—Separation; Purification; Use of additives, e.g. for stabilisation by treatment giving rise to a chemical modification of at least one compound
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Epoxy Compounds (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a method for removing and recycling an azeotrope in methanol, which comprises the steps of leaving GME (1, 2-epoxy-3-methoxypropane) as an impurity in a tower kettle through a methanol rectifying tower to obtain methanol containing AAL (allyl alcohol) and a small amount of water, adding a chlorinating agent into a fraction extracted from the methanol rectifying tower, chlorinating the AAL to generate chloropropene under the condition of absorbing tail gas under a micro negative pressure, and removing the chloropropene from the methanol through a light component removal tower to obtain recycled methanol with the content of not less than 99.9 percent.
Description
Technical Field
The invention relates to the technical field of fine chemical engineering, relates to a solvent recovery technology, and particularly relates to a method for removing an azeotropic substance in recovered methanol.
Background
Epichlorohydrin (ECH) is an important basic chemical raw material and is mainly applied to the production of various products such as epoxy resin, epichlorohydrin rubber, glycerol and the like. At present, the industrial production methods of the epichlorohydrin mainly comprise two methods: the chlorohydrin process and the glycerol process. The chlorohydrin process has the disadvantages of serious corrosion to equipment and environmental pollution, and generates about 40 tons of salt-containing wastewater per 1 ton of epichlorohydrin. The main reaction process of the glycerol method mainly comprises two steps of chlorination and saponification. The glycerol method has fewer byproducts and mild operation conditions, but the production capacity of the epichlorohydrin is greatly limited by the raw material glycerol.
The development of a clean production process of epoxy chloropropane has become an inevitable requirement of times development, wherein the process for synthesizing the epoxy chloropropane by using a titanium-silicon molecular sieve as a catalyst and hydrogen peroxide as an oxygen source becomes a research hotspot due to the advantages of high selectivity, less ineffective decomposition of the hydrogen peroxide and the like.
The process needs to use Methanol (MA) as a solvent, on one hand, hydrogen peroxide is dissolved to form homogeneous reaction liquid, on the other hand, the catalyst is activated, the activity of the catalyst is maintained, and the recovered methanol can be recycled when the content is more than or equal to 99.9 percent. However, in a scale-up experiment, the main impurities in the aqueous phase solution are AAL (allyl alcohol) and GME (1, 2-epoxy-3-methoxypropane), the boiling point difference between the two impurities and methanol is more than 30 ℃ from the view point of the boiling point, when the methanol is recovered by a rectifying tower, the GME can be remained in a tower kettle, but the boiling point difference between the two impurities and the methanol is reduced due to the azeotropic boiling point of the AAL and water, so that the AAL enters the top of the rectifying tower, the content of the methanol is lower, the content of the recovered methanol is less than or equal to 99.5 percent, and the content of the methanol cannot be more than or equal to 99.9 percent even if the rectifying reflux ratio is increased to more than 5.
Because the methanol is a solvent which hardly participates in the reaction and needs to be recycled for a long period, the quality of the recovered methanol directly influences the selectivity of the synthesis of the epichlorohydrin, and finally influences the quality of the finished product. Therefore, a method for removing the azeotrope in the recovered methanol is urgently needed to be developed for the process of epoxy chloropropane by using the hydrogen peroxide method.
Disclosure of Invention
In order to solve the above problems, the present invention provides the following technical solutions:
a process for removing an azeotrope in recovered methanol comprising the steps of: continuously pumping a water phase solution into a methanol rectifying tower for rectification, and pumping fractions into a reaction kettle; adding a chlorinating agent into the reaction kettle for chlorination reaction, carrying out micro-negative pressure reaction, and absorbing the condensed tail gas by an alkaline tower; pumping the reaction liquid in the reaction kettle into a lightness-removing tower for rectification to obtain chloropropene from the top of the tower and recovered methanol from the bottom of the tower; the aqueous phase solution is produced by a hydrogen peroxide method epoxy chloropropane process and comprises the following components: MA:10 to 30 percent; AAL:0.25 to 1 percent; GME:0.15 to 1 percent; ECH:0.01 to 0.3 percent; the balance of water and trace organic impurities; the composition of fractions extracted from the methanol rectifying tower is as follows: AAL:0.3 to 0.9 percent; water: 0.01 to 0.1 percent; the balance being MA.
Further, the chlorinating agent comprises thionyl chloride, phosgene, methyl chloroformate and solid phosgene.
Further, the dosage of the chlorinating agent is 1 to 1.05 times of the AAL equivalent.
Further, the chlorination reaction conditions are as follows: the reaction temperature is 55-70 ℃, the micro negative pressure is-2 to-0.02 kPa, and the reaction time is 0.5-2 h.
Further, the rectification reflux ratio of the light component removal tower is 1-4.
Further, the alkaline tower circularly absorbs the tail gas by adopting a 5% sodium hydroxide solution.
The invention has the following beneficial effects: the method comprises the steps of leaving GME (1, 2-epoxy-3-methoxypropane) as an impurity in a tower kettle through a methanol rectifying tower to obtain methanol containing AAL and a small amount of water, adding a chlorinating agent into a fraction extracted from the methanol rectifying tower, chlorinating the AAL to generate chloropropene under the condition of absorbing tail gas at a slight negative pressure, removing the chloropropene from the methanol through a light removal tower, wherein the content of the obtained recovered methanol is not less than 99.9 percent, so that the content of the recovered methanol meets the requirement of long-period cyclic use of a hydrogen peroxide method epoxy chloropropane process, and the AAL is chlorinated and recovered to obtain the chloropropene, namely the main raw material of the hydrogen peroxide method epoxy chloropropane, so that the waste is changed into the valuable.
Drawings
FIG. 1 is a schematic diagram of the chlorination reaction and the light ends removal process.
In the figure, 1-a reaction kettle, 2-a light component removal tower, 3-a light component removal condenser, 4-a methanol storage tank, 5-a reboiler, 6-a chloropropene storage tank, 7-a chlorination condenser and 8-an alkali absorption tower.
Detailed Description
In order to make the technical means, features and functions of the present invention easier to understand, the technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the detailed description and the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.
All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, adding a fraction extracted from a methanol rectifying tower into a reaction kettle 1, adding a chlorinating agent, feeding reaction tail gas into an alkali absorption tower 8 through a chlorination condenser 7, connecting the alkali absorption tower 8 to a micro negative pressure, and keeping chlorination reaction under the micro negative pressure; pumping the chlorination reaction liquid into a light component removal tower 2, heating the chlorination reaction liquid by a reboiler 5 to evaporate chloropropene in the chlorination reaction liquid from the top of the light component removal tower 2, condensing the chloropropene by a light component removal condenser 3, collecting the recovered chloropropene into a chloropropene storage tank 6, pumping high-purity methanol in a tower kettle of the light component removal tower 2 into a methanol storage tank 4 for storage.
The methanol rectifying towers adopted in the following examples are all conventional methanol rectifying towers, and the aqueous phase solution is produced by the epoxy chloropropane process by a hydrogen peroxide method, and comprises the following components: MA:10 to 30 percent; AAL:0.25 to 1 percent; GME:0.15 to 1 percent; ECH:0.01 to 0.3 percent; the balance of water and trace organic impurities; rectifying the aqueous phase solution by a methanol rectifying tower, wherein the reflux ratio is 1-4, and the obtained fraction comprises the following components: AAL:0.3 to 0.9 percent; water: 0.01 to 0.1 percent; the balance is MA, and the process of rectifying the aqueous phase solution by a methanol rectifying tower in the following examples is not described in detail.
Example 1:
3m 3 the reaction kettle is pumped into a 1200kg methanol rectifying tower to extract distillate, and the composition of the distillate is as follows: MA99.35%; 0.6 percent of AAL; 0.05 percent of water, 15kg of thionyl chloride is added into the reaction kettle, the mixture reacts for 1.5 hours at 65-68 ℃ and negative pressure of-0.15 kpa, and the tail gas (the main component is SO) 2 And HCl) is firstly pumped into an alkaline washing tower for absorption under negative pressure, 5% sodium hydroxide solution is used in the alkaline washing tower for cyclic absorption, chlorinated reaction liquid is rectified under normal pressure through a light component removal tower, the reflux ratio is 1.0, 9.5kg of chloropropene with the content of 99.15% is obtained at the top of the tower (the gas phase temperature is 43-44 ℃), the content of methanol with the content of 99.92% is obtained at the bottom of the tower, and the content of methanol at the bottom of the tower meets the use requirement of epoxidation raw materials.
Example 2
3m 3 A reaction kettle, pumping into 1000kg of methanol rectifying tower to extract distillate, wherein the composition of the distillate is MA99.24%; 0.75% of AAL; 0.01 percent of water, 12.5kg of phosgene is introduced, the reaction is carried out for 1 hour at the temperature of between 55 and 58 ℃ and under the pressure of minus 0.05kpa, and tail gas (the main component is CO) 2 And HCl) is firstly pumped into an alkaline washing tower under negative pressure for absorption, the alkaline washing tower uses 5% sodium hydroxide solution for circular absorption, chlorinated reaction liquid is rectified under normal pressure through a light component removal tower, the reflux ratio is 2.0, 10.0kg of chloropropene with the content of 99.34% is obtained at the top of the tower (the gas phase temperature is 43-44 ℃), methanol with the content of 99.90% is obtained at the bottom of the tower, and the methanol content at the bottom of the tower meets the use requirement of epoxidation raw materials.
Example 3
3m 3 A reaction kettle, into which 900kg of methanol rectifying tower is pumped to extract distillate, the composition of which is MA99.11%; 0.8 percent of AAL; 0.09 percent of water, 6kg of methyl chloroformate is added into the reaction kettle, the reaction is carried out for 2 hours at the temperature of 60 to 62 ℃ and under the negative pressure of-0.12 kpa, and the tail gas (the main component is CO) 2 And HCl) is firstly pumped into an alkaline washing tower for absorption under negative pressure, 5% sodium hydroxide solution is used in the alkaline washing tower for cyclic absorption, chlorinated reaction liquid is rectified under normal pressure through a light component removal tower, the reflux ratio is 3.0, 9.6kg of chloropropene with the content of 99.47% is obtained at the top of the tower (the gas phase temperature is 43-44 ℃), methanol with the content of 99.93% is obtained at the bottom of the tower, and the methanol content at the bottom of the tower meets the use requirement of epoxidation raw materials.
Example 4
3m 3 A reaction kettle, pumping 1000kg of methanol rectifying tower to extract distillate, the composition of which is MA99.34%; 0.61% of AAL; 0.05 percent of water, 10.5kg of solid phosgene is added into a reaction kettle, the reaction is carried out for 1 hour at the temperature of 63 to 65 ℃ and under the negative pressure of-0.07 kpa, and tail gas (the main component is CO) 2 And HCl) is firstly pumped into an alkaline washing tower for absorption under negative pressure, 5% sodium hydroxide solution is used for cyclic absorption in the alkaline washing tower, chlorinated reaction liquid is rectified under normal pressure in a light component removal tower, the reflux ratio is 1.5, 8kg of chloropropene with the content of 99.24% is obtained at the top of the tower (the gas phase temperature is 43-44 ℃), the content of methanol with the content of 99.91% is obtained at the bottom of the tower, and the content of methanol at the bottom of the tower meets the use requirement of epoxidation raw materials.
Example 5
3m 3 The reaction kettle is pumped into a 1000kg methanol rectifying tower to extract fraction, and the fraction is composed ofBecoming MA99.08%; 0.9 percent of AAL; 0.02 percent of water, 15kg of phosgene is introduced, the reaction is carried out for 1.5h at the temperature of 62 to 64 ℃ and under the negative pressure of-0.1 kpa, and tail gas (the main component is CO) 2 And HCl) is firstly pumped into an alkaline washing tower for absorption under negative pressure, 5% sodium hydroxide solution is used in the alkaline washing tower for cyclic absorption, chlorinated reaction liquid is rectified under normal pressure through a light component removal tower, the reflux ratio is 4.0, 11.7kg of chloropropene with the content of 99.54% is obtained at the top of the tower (the gas phase temperature is 43-44 ℃), methanol with the content of 99.92% is obtained at the bottom of the tower, and the methanol content at the bottom of the tower meets the use requirement of epoxidation raw materials.
Example 6
3m 3 A reaction kettle, into which 1200kg of methanol rectifying tower is pumped to extract distillate, the components of which are MA99.25 percent and AAL0.7 percent; 0.05 percent of water, adding 17.2kg of thionyl chloride into the reaction kettle, reacting for 1 hour at the temperature of between 55 and 58 ℃ and under the negative pressure of-0.12 kpa, and discharging tail gas (the main component is SO) 2 And HCl) is firstly pumped into an alkaline washing tower for absorption under negative pressure, 5 percent sodium hydroxide solution is used in the alkaline washing tower for cyclic absorption, chlorinated reaction liquid is rectified under normal pressure through a light component removal tower, the reflux ratio is 2.5, 11kg of chloropropene with the content of 99.38 percent is obtained at the top of the tower (the gas phase temperature is 43-44 ℃), methanol with the content of 99.9 percent is obtained at the bottom of the tower, and the methanol content at the bottom of the tower meets the use requirement of epoxidation raw materials.
Example 7
3m 3 A reaction kettle, pumping into 1000kg of methanol rectifying tower to extract distillate, wherein the components of the distillate comprise 99.05 percent of MA and 0.85 percent of AAL; 0.1 percent of water, 14.5kg of methyl chloroformate is added into the reaction kettle, the reaction is carried out for 0.5h at 68-70 ℃ and under negative pressure of-0.20 kpa, and tail gas (the main component is CO) 2 And HCl) is pumped into an alkaline washing tower under negative pressure to be absorbed, the alkaline washing tower uses 5% sodium hydroxide solution to circularly absorb, chlorinated reaction liquid is rectified under normal pressure through a light component removal tower, the reflux ratio is 2.0, 10.5kg of chloropropene with the content of 99.29% is obtained at the top of the tower (the gas phase temperature is 43-44 ℃), methanol with the content of 99.93% is obtained at the bottom of the tower, and the methanol content at the bottom of the tower meets the use requirement of epoxidation raw materials.
Example 8
3m 3 A reaction kettle, pumping into 1000kg of methanol rectifying tower to extract distillate, wherein the components of the distillate comprise 99.62 percent of MA and 0.30 percent of AAL; 0.08 percent of water, and 5.4k of water is added into the reaction kettleg solid phosgene, reacting for 2 hours at the temperature of between 60 and 62 ℃ and under the negative pressure of-0.12 kpa, and exhausting gas (the main component is CO) 2 And HCl) is firstly pumped into an alkaline washing tower for absorption under negative pressure, 5 percent sodium hydroxide solution is used in the alkaline washing tower for cyclic absorption, chlorinated reaction liquid is rectified under normal pressure through a light component removal tower, the reflux ratio is 3.0, 3.7kg of chloropropene with the content of 99.42 percent is obtained at the top of the tower (the gas phase temperature is 43-44 ℃), methanol with the content of 99.9 percent is obtained at the bottom of the tower, and the methanol content at the bottom of the tower meets the use requirement of epoxidation raw materials.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made to the present invention by those skilled in the art. Any modification or equivalent substitution made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A method for removing an azeotrope in recovered methanol, comprising the steps of: continuously pumping the aqueous phase solution into a methanol rectifying tower for rectification, and pumping the distillate into a reaction kettle; adding a chlorinating agent into the reaction kettle for chlorination reaction, carrying out micro-negative pressure reaction, and absorbing the condensed tail gas by an alkaline tower; pumping the reaction liquid in the reaction kettle into a light component removal tower for rectification to obtain chloropropene from the top of the tower and recovered methanol from the bottom of the tower; the aqueous phase solution is produced by a hydrogen peroxide epoxy chloropropane process and comprises the following components: MA:10 to 30 percent; AAL:0.25 to 1 percent; GME:0.15 to 1 percent; ECH:0.01 to 0.3 percent; the balance of water and trace organic impurities; the composition of fractions extracted from the methanol rectifying tower is as follows: AAL:0.3 to 0.9 percent; water: 0.01 to 0.1 percent; the balance being MA.
2. The method for removing azeotropes in the recovery of methanol as claimed in claim 1, wherein said chlorinating agent comprises thionyl chloride, phosgene, methyl chloroformate and phosgene solids.
3. The method for removing an azeotrope in methanol recovery according to claim 1, wherein the chlorinating agent is used in an amount of 1 to 1.05 times the AAL equivalent.
4. The method for removing an azeotrope in methanol recovery according to claim 1, wherein the chlorination reaction conditions are: the reaction temperature is 55-70 ℃, the micro negative pressure is-0.2 to-0.02 kPa, and the reaction time is 0.5-2 h.
5. The method for removing an azeotropic material in the recovered methanol according to claim 1, wherein the rectification reflux ratio of the light component removal column is 1 to 4.
6. The method for removing azeotropic substances in the recovered methanol, as claimed in claim 1, wherein the caustic scrubber circularly absorbs the tail gas by using 5% sodium hydroxide solution.
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| JPH0733698A (en) * | 1993-07-22 | 1995-02-03 | Showa Denko Kk | Purification of 2,3-dichloro-1-propanol |
| CN1362942A (en) * | 2000-02-15 | 2002-08-07 | 昭和电工株式会社 | Process for production of allyl chloride |
| CN103664505A (en) * | 2013-12-24 | 2014-03-26 | 山东海益化工科技有限公司 | Chloropropene production technology |
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