CN115594567B - Separation method of dimethyl carbonate/methanol mixture - Google Patents

Separation method of dimethyl carbonate/methanol mixture Download PDF

Info

Publication number
CN115594567B
CN115594567B CN202211230701.5A CN202211230701A CN115594567B CN 115594567 B CN115594567 B CN 115594567B CN 202211230701 A CN202211230701 A CN 202211230701A CN 115594567 B CN115594567 B CN 115594567B
Authority
CN
China
Prior art keywords
separation
methanol
auxiliary agent
water
dimethyl carbonate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202211230701.5A
Other languages
Chinese (zh)
Other versions
CN115594567A (en
Inventor
王庆
苟永桢
陈学良
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Liaoning Sanye Environmental Protection Technology Co ltd
Original Assignee
Liaoning Sanye Environmental Protection Technology Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Liaoning Sanye Environmental Protection Technology Co ltd filed Critical Liaoning Sanye Environmental Protection Technology Co ltd
Priority to CN202211230701.5A priority Critical patent/CN115594567B/en
Publication of CN115594567A publication Critical patent/CN115594567A/en
Application granted granted Critical
Publication of CN115594567B publication Critical patent/CN115594567B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
    • 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
    • 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
    • C07C29/86—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by liquid-liquid treatment
    • 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
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C68/00—Preparation of esters of carbonic or haloformic acids
    • C07C68/08—Purification; Separation; Stabilisation
    • 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)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention relates to a separation method of a dimethyl carbonate/methanol mixed solution, which comprises the following steps: the sample to be separated containing the dimethyl carbonate and the methanol and the separation auxiliary agent are reacted and rectified in a reaction rectifying tower to finish primary separation, the product of the primary separation is secondarily mixed with the separation auxiliary agent, oil-water phase separation is carried out, crude dimethyl carbonate is obtained, and the dimethyl carbonate with higher purity can be obtained through a simple rectifying tower; the separated water phase and the separating tower bottom liquid in the previous step are subjected to simple rectification to obtain methanol and recovered separating auxiliary agent. The recovered separation aid can be recycled. The separation aid includes a water-soluble salt selected from at least one of an alkali metal salt, an alkaline earth metal salt, and a transition metal salt, and water. The invention adopts water-soluble salt as main separation auxiliary agent, methanol reacts with salt to generate crystalline alcohol compound of salt, and the crystalline alcohol has the characteristic similar to crystal water and has relatively stable structure at lower temperature. By utilizing the characteristics, the dimethyl carbonate and the methanol can be well separated through the technical processes of reactive distillation, oil-water phase separation and the like. Compared with the traditional separation method, the separation method provided by the invention has the advantages that the adopted raw materials are simple and easy to obtain, the raw materials are easy to separate from methanol, the raw materials can be continuously utilized, the separation effect is high, the energy consumption is lower, and the separation method is economical and practical.

Description

Separation method of dimethyl carbonate/methanol mixture
Technical Field
The invention relates to the technical field of compound separation, in particular to a separation method of a dimethyl carbonate/methanol mixture.
Background
As an important industrial solvent and an organic synthesis intermediate, dimethyl carbonate (DMC) is a green chemical raw material with low toxicity, excellent environmental protection performance, wide application and development prospect.
Methanol is also an important bulk organic chemical raw material and is widely used in various industrial processes.
The problem of separation of the dimethyl carbonate/methanol mixture has long been felt. The dimethyl carbonate/methanol system azeotropes at 63.5 ℃ with an azeotropic composition of approximately 70% methanol and 30% DMC. When dimethyl carbonate starts to rise from the last 80 th century as a novel green chemical raw material, the problem of separation of a coexisting system of dimethyl carbonate/methanol cannot be mostly bypassed regardless of the production or application of dimethyl carbonate.
The separation methods of the dimethyl carbonate/methanol mixture reported in the prior literature mainly comprise a pressure rectification method, an extraction rectification method, an azeotropic rectification method, a low-temperature crystallization method, a membrane separation method and the like. The pressure rectification method and the extraction rectification method are the mainstream separation methods. The steam consumption of the separation by the pressurized rectification method is high, the pressure and temperature requirements of the used equipment are high, the requirements on the equipment are high, and the relative energy consumption is high; the solvent extraction method has lower production cost, but is easier to remain solvent impurities in the product, so that the difficulty of further improving the purity is higher, and the method is difficult to be applied to the field with higher requirements on the purity; the low temperature crystallization process utilizes the characteristic that DMC has freezing point higher than that of methanol (-97.8 deg.c), and has DMC solidification crystallization at proper temperature, separation and distillation to obtain DMC with DMC recovering rate up to 95-96%. However, the azeotrope is crystallized at-35 ℃, then the temperature is increased for secondary distillation, the energy consumption is high, the operation is difficult, and the flow is complex. The membrane separation method requires a separation membrane with high cost, which is disadvantageous in reducing the cost. Based on this, it is necessary to provide a separation method of a dimethyl carbonate/methanol mixture which has a high separation effect, low energy consumption and is economical and practical.
At present, the patent proposes to use inorganic matters and water as a co-extractant to separate dimethyl carbonate from methanol, for example, the patent CN201911363417.3 extracts methanol into water phase through good intersolubility of methanol and water, and the salt only plays a physical role, so as to increase the density of water phase and accelerate the phase separation of oil and water.
Methanol is used as a small molecular polar organic compound, has a plurality of properties similar to water, and is easy to generate association reaction with salts to generate crystallization alcohol similar to crystallization water. Whereas the salt of the association product with the crystalline alcohol may exist stably over a range of temperatures. The continuous and efficient separation of dimethyl carbonate and methanol by utilizing the principle is not reported for obtaining high-purity DMC and methanol. Based on this, the present invention has been made.
Disclosure of Invention
A method for separating dimethyl carbonate from methanol, comprising the following steps:
the sample to be separated contains dimethyl carbonate and methanol, DMC content in the sample is 20-80%, and the rest is methanol and other trace impurities generated in the transesterification reaction process;
separating the sample to be separated by adopting a separation auxiliary agent; the separation aid includes a water-soluble salt selected from at least one of an alkali metal salt, an alkaline earth metal salt, and a transition metal salt, and water.
The invention adopts water soluble salt and water as separation auxiliary agent, part of water soluble salt and methanol are associated with methanol at lower temperature to generate salt containing crystallization alcohol, the salt has certain stability to ensure that a large amount of methanol is not decomposed in the process of reactive distillation, so that most of methanol is left in liquid phase, and dimethyl carbonate and a small amount of unreacted methanol are distilled out through vapor phase to be used as distillate for further separation.
Further, the distillate is fully mixed with a separation auxiliary agent according to a certain proportion, oil-water phase separation is carried out through a process similar to extraction layering, methanol in the distillate is remained in a water phase, and the upper oil phase is dimethyl carbonate with higher purity (> 97%).
The aqueous solution containing the water-soluble salt of crystalline alcohol is distilled at a higher temperature to decompose almost completely, thereby distilling off methanol. The separation auxiliary agent of the methanol is removed, and the methanol is recycled after the water is properly supplemented.
Compared with the traditional separation method, the separation method provided by the invention has the advantages that the adopted auxiliary agent is simple and easy to obtain, can be recycled, and has the advantages of high separation effect, low energy consumption, economy and practicability.
In some embodiments, the water-soluble salt is selected from at least one of a sodium salt, a magnesium salt, a calcium salt, a copper salt, a zinc salt, and a barium salt.
In some of these embodiments, the water-soluble salt is selected from at least one of the chlorides, sulfates of the metal cations described above.
In some of these embodiments, the separation aid is added as an aqueous solution of the water-soluble salt; in the separation auxiliary agent, the mass content of the water-soluble salt is 20-50%.
In some of these embodiments, in the step of separating, the volume ratio of the separation aid to the sample to be separated is (0.5-5): 1; the mass content of the dimethyl carbonate in the sample to be separated is 20% -80%.
In some of these embodiments, after the step of separating, the method further comprises the step of:
further rectifying the separated methanol to obtain methanol meeting national standards; and/or
And further rectifying the separated dimethyl carbonate, and separating to obtain dimethyl carbonate meeting national standards.
In some of these embodiments, the method further comprises the step of:
and returning the separation auxiliary agent after rectifying and separating the methanol to the separation step for recycling.
Drawings
FIG. 1 is a process flow diagram of an example method for separating dimethyl carbonate from methanol.
Detailed Description
The present invention will be described more fully hereinafter in order to facilitate an understanding of the present invention, and preferred embodiments of the invention are set forth, which are provided to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, an embodiment of the present invention provides a method for separating dimethyl carbonate from methanol, which includes steps S1 to S4 and/or S5 to S6 as follows:
and S1, carrying out reactive distillation on a sample to be separated containing dimethyl carbonate and methanol and a separation auxiliary agent through a reactive distillation tower.
And S2, secondarily mixing the overhead gas phase distillate obtained by the reaction rectification with a separation auxiliary agent, and carrying out oil-water phase separation.
And S3, feeding the oil phase separated in the step S2 into a coarse distillation tower to remove the separation auxiliary agent.
And S4, merging the water phase materials separated in the steps S1, S2 and S3 and tower bottom liquid, feeding the mixture into an auxiliary agent recovery tower, separating methanol from a separation auxiliary agent, obtaining a crude methanol product at the tower top, and recovering the separation auxiliary agent at the tower bottom. The recovered separation aid may be re-entered into the separation process.
And step S5, rectifying the tower top distillate of the step S3 further to obtain the high-purity DMC product (> 99.99 wt%).
And S6, rectifying the crude methanol obtained in the step S5 further to obtain a methanol product (> 99.85 wt%).
As described in the background art, the conventional separation method of dimethyl carbonate and methanol generally employs a pressure rectification method, an extractive rectification method, an azeotropic rectification method, a low-temperature crystallization method, a membrane separation method, and the like. The extraction separation method adopts an extracting agent which is generally an organic extracting agent such as glycol, and the organic extracting agent introduced by the method is used as an organic solvent, has an influence on the purity of methanol and has higher cost.
The invention adopts the association reaction of water soluble salt and methanol to generate crystalline alcohol compound, separates dimethyl carbonate from methanol by the relatively stable crystalline alcohol compound, and enables the dimethyl carbonate to be well separated from the methanol by secondary phase separation. Compared with the traditional separation method, the separation method provided by the invention has the advantages that the adopted separation auxiliary agent is simple and easy to obtain, is easy to separate from methanol, can be continuously utilized, and has high separation effect, lower energy consumption, economy and practicability.
In some embodiments, the water-soluble salt is selected from at least one of a sodium salt, a magnesium salt, a calcium salt, a copper salt, a zinc salt, and a barium salt. Further, the water-soluble salt is at least one selected from the group consisting of chlorides and sulfates of the above-mentioned metal cations.
In a specific embodiment, the water-soluble salt is preferably calcium chloride, zinc chloride, barium chloride, sodium sulfate, and copper sulfate, more preferably calcium chloride, zinc chloride, barium chloride. This is because the crystalline alcohol associates of calcium chloride, zinc chloride, barium chloride have a higher methanol association ratio or have better stability of the association, and are less likely to decompose in a relatively low temperature range, facilitating separation.
In one embodiment, different separation aids are adopted in the reaction rectification and oil-water phase separation processes, the operation separation effect is better, but the recovery of the separation aids is relatively complex: separate processing is required.
Further, in the separation auxiliary agent, the mass content of the water-soluble salt is 20-50%. Further, in the separation step, the volume ratio of the separation aid to the sample to be separated is (0.5-5): 1. Wherein the mass content of the dimethyl carbonate in the sample to be separated is 20-80%.
It will be appreciated that in order to continue the separation process, the concentration of the water-soluble salt in the separation aid after recovery of the separation aid needs to be monitored in real time and water replenished in an appropriate amount according to the monitoring result.
The following are specific examples.
Examples 1 to 6
In examples 1 to 6, 20kg of a sample to be separated containing dimethyl carbonate and methanol (dimethyl carbonate content: 30%) was treated by using a process flow chart shown in FIG. 1, and the sample and the separation aid were fed into a reactive rectifying column at normal temperature in a predetermined ratio. The theoretical plates of the reactive rectifying tower are 40, the separation auxiliary agent enters from the upper part of the 15 th plate, and the separation sample enters from the 30 th plate. Obtaining distillate rich in dimethyl carbonate from the top of the tower, wherein the top temperature is 75-85 ℃, and the reflux ratio is 1-4:1; the mixed liquor rich in methanol is obtained from the tower kettle, and the temperature of the tower kettle is 85-95 ℃. Cooling the tower top distillate, mixing with separating assistant in certain proportion, separating oil from water in separating tank, and adding dimethyl carbonate in the upper layer oil phase over 98%. The upper oil phase material enters a crude distillation tower for rectification, the reflux ratio is 0.5-5, the temperature of the top of the tower is 89-91 ℃, and the dimethyl carbonate which does not contain residual impurities and has the content more than 98% compared with the raw materials is obtained. If the raw material comes from byproducts of producing other esters based on transesterification, the product can be reused in the transesterification as a reaction raw material. If the starting material is from a dimethyl carbonate production line, further purification is required to bring the product to the commercial dimethyl carbonate requirements.
The tower bottoms of the reaction rectification tower, the water phase separated from the oil phase and the crude distillation tower are combined together (the embodiment 2 is treated separately, the principle process is the same and is not repeated), and the mixture enters an auxiliary agent recovery tower. The number of the tower plates of the auxiliary agent recovery tower is 40, feeding is carried out from the upper part of the 25 th tower plate, the feeding temperature is 60-65 ℃, and the tower top temperature is 64-65 ℃, so that methanol with the concentration of more than 97% is obtained; the temperature of the tower kettle is 110-130 ℃, and the separation auxiliary agent with the methanol content less than 2% is obtained. After the separation auxiliary agent is properly supplemented with water, the separation auxiliary agent enters into circulation for repeated use. The purity of the methanol obtained from the top of the tower can meet most of market applications with low requirements. If the product is sold as a national standard product, the product needs to be further purified.
The mass content and yield of the separation aids, dimethyl carbonate and methanol products used in the steps of examples 1 to 6 are shown in the following Table 1, and the other conditions are the same. The further purification steps are identical to the purification process flows of the prior art and will not be described further here.
TABLE 1
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (4)

1. The separation method of the dimethyl carbonate/methanol mixed solution is characterized in that a separation auxiliary agent is adopted to separate the sample to be separated; the sample to be separated is a mixed solution of dimethyl carbonate and methanol, wherein the content of the dimethyl carbonate is about 30 percent; the separation aid comprises a water-soluble salt selected from at least one of an alkali metal salt, an alkaline earth metal salt, and a transition metal salt, and water; the separation method is a process comprising the following steps S1 to S4 and/or S5 to S6:
s1, carrying out reactive distillation on a sample to be separated containing dimethyl carbonate and methanol and a separation auxiliary agent through a reactive distillation tower; the mass ratio of the separation auxiliary agent to the sample to be separated is (0.5-5): 1; the separation auxiliary agent enters from the upper part of the tower and reacts with the steam of the sample to be separated from the tower bottom in a countercurrent way to finish the reaction and rectification process;
step S2, secondarily mixing the overhead gas phase distillate obtained by the reaction rectification with a separation auxiliary agent, and carrying out oil-water phase separation;
s3, enabling the oil phase separated in the step S2 to enter a coarse distillation tower, and removing the separation auxiliary agent;
s4, merging the water phase materials separated in the steps S1, S2 and S3 and tower bottom liquid, feeding the mixture into an auxiliary agent recovery tower, separating methanol from a separation auxiliary agent, obtaining a crude methanol product at the tower top, and recovering the separation auxiliary agent at the tower bottom, wherein the recovered separation auxiliary agent can enter the separation process again;
step S5, rectifying the overhead product obtained in the step S3 to obtain a high-purity dimethyl carbonate product;
and S6, rectifying the crude methanol obtained in the step S5 to obtain a methanol product.
2. The separation method of claim 1, wherein the water-soluble salt is selected from at least one of the group consisting of sodium salt, calcium salt, zinc salt, barium salt, chloride of copper salt, and sulfate.
3. The separation method according to claim 2, wherein the water-soluble salt is at least one selected from the group consisting of sodium sulfate, calcium chloride, zinc chloride, barium chloride and copper sulfate.
4. The separation method according to claim 1, wherein the separation aid is added in the form of an aqueous solution formed by mixing the water-soluble salt and water; in the separation auxiliary agent, the mass content of the water-soluble salt is 20-50%.
CN202211230701.5A 2022-10-09 2022-10-09 Separation method of dimethyl carbonate/methanol mixture Active CN115594567B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202211230701.5A CN115594567B (en) 2022-10-09 2022-10-09 Separation method of dimethyl carbonate/methanol mixture

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202211230701.5A CN115594567B (en) 2022-10-09 2022-10-09 Separation method of dimethyl carbonate/methanol mixture

Publications (2)

Publication Number Publication Date
CN115594567A CN115594567A (en) 2023-01-13
CN115594567B true CN115594567B (en) 2023-12-05

Family

ID=84847534

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202211230701.5A Active CN115594567B (en) 2022-10-09 2022-10-09 Separation method of dimethyl carbonate/methanol mixture

Country Status (1)

Country Link
CN (1) CN115594567B (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109422650A (en) * 2017-08-28 2019-03-05 中国石油化工股份有限公司 The continuous separation method of dimethyl carbonate and carbinol mixture
CN109422648A (en) * 2017-08-28 2019-03-05 中国石油化工股份有限公司 Dimethyl carbonate and methanol azeotrope continuous extraction distillation and separation method
CN111004092A (en) * 2019-12-26 2020-04-14 岳阳昌德环境科技有限公司 Method for separating dimethyl carbonate and methanol

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109422650A (en) * 2017-08-28 2019-03-05 中国石油化工股份有限公司 The continuous separation method of dimethyl carbonate and carbinol mixture
CN109422648A (en) * 2017-08-28 2019-03-05 中国石油化工股份有限公司 Dimethyl carbonate and methanol azeotrope continuous extraction distillation and separation method
CN111004092A (en) * 2019-12-26 2020-04-14 岳阳昌德环境科技有限公司 Method for separating dimethyl carbonate and methanol

Also Published As

Publication number Publication date
CN115594567A (en) 2023-01-13

Similar Documents

Publication Publication Date Title
US4115530A (en) Process for obtaining gaseous hydrogen chloride from dilute, aqueous hydrochloric acid
US20130284584A1 (en) Process for separating ethylene glycol and 1, 2-butanediol
KR100733400B1 (en) Azeotropic Distillation Process for Separating Acetic Acid, Methyl Acetate and Water
US8231765B2 (en) Process for the purification of lactams
US5028735A (en) Purification and preparation processes for methyl methacrylate
CN108341763B (en) Caprolactam crystallization and purification method
KR20080105088A (en) Process for the preparation of an alkanediol and a dialkyl carbonate
CN110156811B (en) Synthetic preparation method of pentaerythritol dicyclo sulfate
CN111004092B (en) Method for separating dimethyl carbonate and methanol
CN111662161A (en) Method for separating water-ethanol-isopropanol mixture by extractive distillation
CN110922292B (en) Preparation method of chloromethane
US3406100A (en) Purification of synthetic methanol by extractive distillation and subsequent distillation with plural side stream purges
CN115594567B (en) Separation method of dimethyl carbonate/methanol mixture
CN112661787B (en) Preparation method of antioxidant tri (2, 4-di-tert-butylphenyl) phosphite
CN113512052A (en) Preparation process of lithium difluoroborate
CN110066249B (en) Novel caprolactam refining and purifying method
CN111100008B (en) Regeneration recovery device and method for methanol alkali metal salt catalyst in process of synthesizing dimethyl carbonate by transesterification
JPS6261006B2 (en)
CN106966980B (en) The preparation method of high-purity Eptazocine intermediate
GB2104510A (en) Production of methylnaphthalenes and tar bases including indole
US2878103A (en) Robell ctal
CN115215831A (en) Method for preparing fluoroethylene carbonate fine product
CN111646916A (en) Method for co-producing trifluoroacetamide and ammonium bifluoride from hexafluoropropylene oxide by-product
US6494996B2 (en) Process for removing water from aqueous methanol
US3321284A (en) Extraction of hydrazine from aqueous solution using a fluorinated alcohol

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant