CN108164400A - Synthesize the process of polymethoxy dimethyl ether reaction product separation - Google Patents
Synthesize the process of polymethoxy dimethyl ether reaction product separation Download PDFInfo
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- CN108164400A CN108164400A CN201810107244.8A CN201810107244A CN108164400A CN 108164400 A CN108164400 A CN 108164400A CN 201810107244 A CN201810107244 A CN 201810107244A CN 108164400 A CN108164400 A CN 108164400A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
- C07C41/48—Preparation of compounds having groups
- C07C41/58—Separation; Purification; Stabilisation; Use of additives
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/06—Flash distillation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
- B01D3/40—Extractive distillation
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Abstract
The invention belongs to Chemical Engineering and Technology fields, more particularly to a kind of process for synthesizing the separation of polymethoxy dimethyl ether reaction product, the product mixtures process for synthesizing polymethoxy dimethyl ether (PODEn) with concentrated formaldehyde aqueous solution as catalytic material using dimethoxym ethane is detached.It is completed by operating pressure from three conventional rectification towers being depressured close to normal pressure to negative pressure successive and one close to the flash tank of the ion liquid abstraction rectifying column of atmospheric operation and a set of recycling ionic liquid.High-purity PODE3 5 (or PODE3 6) can be produced.Extend also to the other multiple product schemes compatible with said program.
Description
Technical field
The invention belongs to Chemical Engineering and Technology fields, and in particular to the reaction product separation of synthesis polymethoxy dimethyl ether
Process.
Background technology
Polymethoxy dimethyl ether (also known as polymethoxy methylal, polyoxymethylene dimethyl ether, general formula CH3(OCH2)nOCH3,
English abbreviation PODEn, usual n=2-10) be a kind of high boiling liquid mixture, be averaged Cetane number up to more than 76, and with
It the increase of the degree of polymerization and is significantly increased, average oxygen content 47%-50%, flash-point is about 65.5 DEG C, PODEn's (n=3-6)
Boiling point is about 160-280 DEG C, is a kind of cleaning, high cetane number diesel oil blending component.By a certain percentage (such as 10v%) with it is general
Logical diesel oil blending can significantly improve the oxygen content of finished diesel fuel, and diesel engine fuel is promoted fully to burn and significantly subtract
Few NOx, the pollutants such as CO and PM discharge, it is not required that carrying out any transformation with the oil supply system of engine.In addition, by
Ordinary diesel oil is diluted in addition polymethoxy dimethyl ether, correspondingly also makes aromatic compound and sulfide in finished diesel fuel
Content all reduce.
Polymethoxy dimethyl ether can be by synthesis gas via methanol, formaldehyde, dimethoxym ethane, metaformaldehyde or paraformaldehyde etc.
It is synthesized using few processing step.Cooking technique is tied to form by Material synthesis methanol etc. of coal, natural gas and oven gas.
Coal in China rich reserves, Development of Coal base methanol industry have huge resources advantage.However, methanol excess capacity in recent years
Problem is very prominent, and the device utilization of capacity is only 50% or so.There is an urgent need to further extend the bulk product industry of coal-based methanol
Chain vitalizes storage resources.Development Technology is advanced, economical rationality, using methanol as the industry of the polymethoxy dimethyl ether of upstream raw material
Synthetic technology is not only able to provide a kind of new technology, and can also improve finished diesel fuel to significantly improve finished diesel fuel quality
The raw material mix of production is allowed to more adapt to the endowment of resources of China's fossil energy and the reality constructs of primary energy production, greatly
The deliverability of high-quality finished diesel fuel is improved greatly, promotes the strategic security of China's engine liquid fluid fuel supply.
It in terms of the synthesis of polymethoxy dimethyl ether, has done a lot of work both at home and abroad, studied respectively and has developed profit
It is raw material with methanol, dimethoxym ethane, low-carbon alcohols, formalin, metaformaldehyde, paraformaldehyde etc., using acidic catalyst, obtains
The polymethoxy dimethyl ether product of n=2-10.
In various raw material routes, using metaformaldehyde or paraformaldehyde and dimethoxym ethane as Material synthesis polymethoxy methylal
Research it is more.
Since metaformaldehyde synthetic technology is complex, cost is higher under present condition particularly in China, with trimerization first
Aldehyde and dimethoxym ethane do not have applied economics as Material synthesis polymethoxy dimethyl ether.
Using paraformaldehyde powder and dimethoxym ethane as raw material, catalyzing and synthesizing polymethoxy dimethyl ether with acidic catalyst has
The advantages that purpose product once through yield is high, and by-product is less, and product mixtures separation is easier to.But due to paraformaldehyde powder
Expect depolymerization slowly and viscosity is high during depolymerization, in order to improve the Global reaction Rate of initial reaction stage, it has to using multistage slurry
Bed reactor, paraformaldehyde powder carry technology is more complicated with equipping in addition, can all increase primary investment.
Therefore, develop using dimethoxym ethane and concentrated formaldehyde aqueous solution as raw material, catalyzed and synthesized under acidic catalyst effect poly-
The industrialization advanced technology of methoxyl group dimethyl ether is the wise selection for meeting current China's actual conditions.
Research shows that when using dimethoxym ethane and concentrated formaldehyde aqueous solution as Material synthesis polymethoxy dimethyl ether, in raw material
Water can cause a series of side reactions.First, formaldehyde monomers are very active in itself, can be with water association for methylene glycol MG1 or even into one
Step generation polymethoxy methylene glycol MGn (wherein n is the methoxyl group degree of polymerization), and mutually converting between them is reversible.
In addition, under acid catalysed conditions, the by-product generated due to the direct participation of water has methanol, formic acid and hemiacetal HF1.Hemiacetal
It can also be used as the secondary byproduct that level-one by-product carbinol is catalyzed and synthesized with formaldehyde；Methyl formate can also be used as level-one by-product
The secondary byproduct of esterification occurs between object methanol and formic acid；It is de- that dimethyl ether can also be used as the catalysis of level-one by-product carbinol
The secondary byproduct of water.From this, water in raw material all directly or/and take part in indirectly generation by-product carbinol, formic acid,
The side reaction of hemiacetal, methyl formate and dimethyl ether.In addition, hemiacetal HF1 can also be further poly- methoxy with formaldehyde condensation polymer
Base hemiacetal HFn (wherein n is the methoxyl group degree of polymerization).
In conclusion using dimethoxym ethane and concentrated formaldehyde aqueous solution as catalytic material synthesis polymethoxy dimethyl ether not only make be
The chemical reaction characteristic of system complicates, also due to the number of components of mixture of reaction products dramatically increases and makes separating difficulty bigger.
These, all propose significant challenge to industrial separation technology.
CN101198630A discloses a kind of method that polymethoxy dimethyl ether is prepared by methanol and formaldehyde.Due to being also logical
It crosses raw material formalin and has brought water into catalytic reaction system, the constituent of separated object material and quilt of the present invention
The constituent of separation mixture is similar.The product separate section of the system contains four rectifying columns and a phase separator, but
All rectifying columns are directed to the separation of aqueous solution, but are not directed to that by-product in separation process is acid catalyzed aqueous and non-aqueous
The problem of reaction mixture may continue to chemically react.
CN106146266A discloses a kind of technique for preparing polymethoxy dimethyl ether with dimethoxym ethane and concentrated formaldehyde aqueous solution
Method and apparatus.The invention proposes one and includes a lightness-removing column, an extraction tower, an extractant recovery tower and two
Product cutting, five tower piece-rate systems for the treatment of column composition.Since raw material is dimethoxym ethane and concentrated formaldehyde aqueous solution, in acid catalysed conditions
Under will also form the reacting of complexity numerous with aforementioned invention CN101198630A and the component that faces of the present invention, divide
From system, but also have no for the side reaction explanation that particularly by-product related with hydrolysis detaches.
Invention content
For this purpose, the technical problems to be solved by the invention are, for using dimethoxym ethane and high concentration formaldehyde solution as
Catalytic material synthesizes the industrialized needs of polymethoxy dimethyl ether, it is contemplated that separated object system component is more, physical property is complicated and weight
Component boiling point and fusing point span are larger, particularly under conditions of acid and water exist simultaneously, may be used also in equal phase separation
It can continue that the complex characteristics such as the side reactions such as hydrolysis occur, multiple product scheme can be covered, and distillation process is use up by providing one kind
It may simple product separation method.Using dimethoxym ethane and high concentration formaldehyde solution as raw material, polymethoxy two is catalyzed and synthesized
The product mixtures of methyl ether are usually by PODEn (n=2-10), HFn (n=2,3), unreacting material dimethoxym ethane, formaldehyde and its water
Close object and a small amount of free moisture, the compositions such as by-product carbinol, formic acid, hemiacetal and methyl formate.Wherein HFn (n=2,3) with
The equal PODE2-4 boiling ranges of the degree of polymerization approach, and the two is difficult separation.It is suitable in view of their oxygen content, only molecule one
The end group at end is different, and HFn (n=2,3) content is relatively seldom, although by HFn (n=2,3) concoct into diesel oil with etc.
Amount PODE2-3, which concocts to compare into diesel oil, can be such that flash-point slightly reduces, but still can be classified as purpose product.According to specific product side
The difference of case, purpose product generally can, quantity close with it with physical property by PODEn (n=2-10) and boiling range be seldom contains
It cuts and generates in the mixture of oxygen compound HFn (n=2,3) compositions.For example, the PODE2 of the HF2 containing minute quantity can be used as environmental protection
Type solvent, the cleaning blending component that the PODEn (n=3-5 or 3-6) of the HF3 containing minute quantity can be as diesel oil, etc..
A kind of process for synthesizing the separation of polymethoxy dimethyl ether reaction product, using dimethoxym ethane and concentrated formaldehyde aqueous solution as
The product of catalytic material reaction synthesis polymethoxy dimethyl ether (PODEn, n=2-10) is starting material, and reaction product contains PODEn
(n=2-10), it is dimethoxym ethane, formaldehyde monomers, formaldehyde and water are combined into methylene glycol MG1, polymethoxy methylene glycol MGn, a small amount of
The mixture of reaction products separation of moisture, hemiacetal HF1, polymethoxy hemiacetal HFn, methanol, formic acid and methyl formate exists
Three conventional rectification tower towers (B1), tower (B2) and tower (B3), an ion liquid abstraction rectifying column (B4) and separation and recovery ion
It is completed in the device of flash tank (B5) and associated satellite the equipment composition of liquid.
Moreover, the difference according to products scheme requires, PODEn (n=more than purity 99.5% (mass percent) are obtained
3-6), rest part is mainly application performance and polymethoxy hemiacetal HF3 similar in PODE3 in product.It can also give birth to simultaneously
Production of high purity PODE2 and PODEn (n=3-6).
Moreover, three conventional rectification tower towers (B1), tower (B2) and tower (B3) are respectively close to normal pressure, negative pressure and high vacuum
Degree is lower to be operated；One ion liquid abstraction rectifying column (B4) close to normal pressing operation, adopt by ion liquid abstraction rectifying tower bottom
Going out liquid, flash distillation removes the whole moisture and first into distillation system in vacuum flasher (B5) at a temperature of 130-150 DEG C
Alcohol recycles ionic liquid and recycles.
Moreover, mixture of reaction products is separated into two stream stocks of tower top and bottom of towe, tower top vapour in conventional rectification tower (B1)
Mutually after the condensation of stream stock-traders' know-how water-cooled condenser, including dimethoxym ethane, methylene glycol MG1, hemiacetal HF1, methanol, methyl formate, trimerization first
In the liquid phase of aldehyde, water and minute quantity PODE2, reflux of the part as conventional rectification tower 1, quantity is about that distillation system charging is total
The another part for measuring 2/5-2/7 introduces ion liquid abstraction rectifying column (B4) dehydration, separating methanol；Contain polymethoxy dimethyl ether
The mixing of PODE2-10, methylene glycol MG1, dimethoxy methylene glycol MG2, dimethoxy hemiacetal HF2, metaformaldehyde and formic acid etc.
Object introduces conventional rectification tower 2 as charging from the first conventional rectification tower bottom of towe.
Moreover, it is about that distillation system feeds the ion liquid abstraction rectifying and dewatering of total amount 1/2-1/8, separating methanol simultaneously with quantity
Dimethoxym ethane is made further to concentrate, in the overhead condensation liquid of extractive distillation column (B4), dimethoxym ethane is at concentrations up to more than 97%, water content
About in 20PPM hereinafter, methanol content about in 0.6-0.9% hereinafter, which part as reflux, quantity be about distillation system charging
Another part of total amount 1/3-1/5 is recycled to polymethoxy dimethyl ether and catalyzes and synthesizes unit.
Moreover, in conventional rectification tower (B2), charging is separated into two stream stocks of tower top and bottom of towe：Overhead vapor phase is through complete solidifying
After device condensation, partly as reflux, total amount is about another part of distillation system charging total amount 1/3-1/5, and PODE2 concentration exists
60-70% contracts simultaneously containing a small amount of PODE3, metaformaldehyde, methylene glycol MG1, dimethoxy methylene glycol MG2 and dimethoxy half
The mixture of aldehyde HF2 is recycled to polymethoxy dimethyl ether and catalyzes and synthesizes unit, to improve its feed composition, improves purpose product
The selectivity and yield of PODE3-6；Quantity is about distillation system total feed 1/3-1/5, contains polymethoxy dimethyl ether
The bottom liquid mixture of PODE3-10, three polymethoxy hemiacetal HF3 and formic acid introduce conventional rectification tower (B3) as charging.
Moreover, in the conventional rectification tower (B3), the charging including PODE3-10 and minute quantity formic acid be separated into tower top with
The stream stocks of bottom of towe two, overhead vapor phase obtain more than 99.5% purity after complete condenser condenses, PODE3-5 containing a small amount of formic acid or
PODE3-6 can obtain high-purity purpose product PODE3-5 or PODE3-6 after depickling；Bottom of towe is PODE5-8 or PODE6-8 is
Main, the mixture containing a small amount of PODE9-10 is recycled to after the dilution of the reaction raw materials such as the dimethoxym ethane of metering and catalyzes and synthesizes list
Member to improve its feed composition, improves the selectivity and yield of purpose product PODE3-6.
Moreover, ionic liquid used in extracting rectifying is including but not limited to following：Cation is imidazoles, pyridines or quaternary ammonium
Salt etc., anion are bis-trifluoromethylsulfoandimide, tetrafluoroborate, hexafluoro-phosphate radical, acetate or dithyl sulfate etc..
Moreover, used conventional rectification tower and extractive distillation column are packed tower or plate column, optimally, using filler
Tower.
Catalyze and synthesize the process of polymethoxy dimethyl ether (PODEn) product mixtures separation, it is characterised in that：Three
The operating pressure of conventional rectification tower (B1), (B2) and (B3) is respectively 0.15-0.10MPa, 0.03-0.06MPa and 0.003-
0.006MPa, the operating pressure of ion liquid abstraction rectifying column is 0.09MPa-0.10MPa；Conventional rectification tower 1 is close to boiling point
Liquid feedstock, can also the charging of vapour/liquid mixture；Other each towers are the liquid phase feeding close to boiling point.
It moreover, can be with extended products scheme to PODEn (n=3-5 or n=3- can either be produced by adjusting operating parameter
6) environment-friendly type solvent PODE2, can be also produced simultaneously；Or using the second conventional rectification tower overhead as raw material, through in addition
One treating capacity is only the conventional rectification tower of above-mentioned first rectifying column 1/3 or so, according to boiling range by PODE2, HF2 and light component
MG1, HF1 and heavy constituent MG2 are separated, extraction high-purity PODE2, HF2 as solvent, gently, heavy component it is recyclable to urging
It is combined to unit.
Since the main reaction sequence for catalyzing and synthesizing polymethoxy dimethyl ether is reversible reaction, raw material is it is not possible that one way turns completely
Change, the recyclable utilization of raw material after separation.By-product carbinol is the raw material of the raw material dimethoxym ethane of production synthesis PODEn, point
Dimethoxymethane production device can be recycled to after coming by separating out.The degree of polymerization low (such as PODE2) and the high PODEn (examples of the degree of polymerization
Such as PODE6-10) reaction member can also be recirculated back to continue to improve or reduce the degree of polymerization respectively to improve purpose product selectivity
And improve its yield.
As previously mentioned, the water that by-product carbinol, formic acid and methyl formate etc. are directly and/or indirectly brought into raw material formaldehyde
It is related, and according to the purity requirement of purpose product, it is necessary to below moisture removal to correlation standard value.Therefore it is handling
When dimethoxym ethane, methanol, formaldehyde, formic acid, methyl formate and the separation of water or removing scheme, it should fully take into account in formic acid first
Under catalytic action, it may continue to occur between raw material dimethoxym ethane, formaldehyde and its hydrate, methanol, formic acid, methyl formate and water etc.
Side reaction is catalyzed, secondly it is contemplated that the electrolyte solution that formic acid is formed with water may cause electrochemical corrosion to equipment.For
This, should will enter distillation system material in water be separated as early as possible with formic acid, this be not only able to prevention separation process in continue into
Row water participates in, the side reaction of Catalyzed by Formic Acid, is also beneficial to inhibit the electrochemical corrosion of equipment.
Based on mentioned above principle, the present invention is combined using conventional rectification with ion liquid abstraction distillation technology, it is proposed that is closed
The process detached into the product mixtures of polymethoxy dimethyl ether.It is characterized in that：By PODEn (n=2-10), unreacted
Raw material dimethoxym ethane, formaldehyde and its hydrate and a small amount of free moisture, the production of the compositions such as by-product carbinol, formic acid and methyl formate
The separation of object mixture, three conventional rectification towers, one dehydration, separating methanol ion liquid abstraction rectifying column and detach back
It receives in the equipment such as the flash tank 5 of ionic liquid and completes.Its brief flow is as shown in Figure 1.
In Fig. 1 tower B1, tower B2 and tower B3 be concatenation, operating pressure successive reduce conventional rectification tower.Tower 1 is close to normal pressure
Lower operation, tower 2 operate under negative pressure, and tower 3 operates under vacuum.Tower 4 is the ion liquid abstraction rectifying column of atmospheric operation.Tank 5
It is the flash tank for recycling ionic liquid.
Obtained from reaction member, 0.5-1.5MPa and 80-120 DEG C of product mixtures through flash, strip or throttle into
Enter the tower 1 close to atmospheric operation, by stripping section, stripping goes out whole moisture and other lighter components but does not include formic acid,
It takes trace P ODE2 out of simultaneously, rectifying section is entered with vapor phase.Under the operating condition of reflux ratio 1-5, light group in rectifying section
Divide constantly concentration, the distillate part condensed by overhead condenser flows back into tower top, and another part is sent to extractive distillation column 4
It is dehydrated, separating methanol.Contain a small amount of metaformaldehyde, methylene glycol MG1, dimethoxy methylene glycol MG2, dimethoxy hemiacetal
The PODEn of HF2 and minimal amount formic acid (n=2-10) is sent directly into tower 2 as charging from the extraction of 1 bottom of tower.
Tower 2 operates under conditions of about 0.03-0.06MPa and reflux ratio 1.5-5, main to realize PODE2 and PODEn (n
=3-10) separation.Overhead extraction high concentration PODE2 and a small amount of PODE3, metaformaldehyde, methylene glycol MG1, dimethoxy first
Glycol MG2 and dimethoxy hemiacetal HF2, process, which further refines, can be used as environment-friendly type solvent, can also be all or part of
Polymethoxy dimethyl ether synthesis unit is recycled back into, to improve the selections of PODEn (n=3-5 or 3-6) in the reaction product
Property.PODEn (n=3-10) the bottom of towe Produced Liquid for containing only a small amount of organic acid and HF3 is sent directly into tower 3 as charging.
Tower 3 operates under conditions of about 0.003-0.006MPa and reflux ratio 1.0-5.0, major function be from
The purpose product PODEn (n=3-5) or PODEn (n as diesel oil cleaning component are cut into PODEn (n=3-10) mixture
=3-6).It is required according to the difference to purpose product polymerization scope, it is appropriate to adjust gating location or bottom temperature.Tower top evaporates
Go out containing a small amount of organic acid in object, purpose product purity is more than 99.5%.It cools down and passes through conventional weakly-basic anion and exchange
Qualified purpose product is can obtain after the depicklings such as resin adsorption processing.PODEn (n=5-10 or the n=6- produced from bottom of towe
10) liquid mixture is recirculated back to after material liquid dilutes and catalyzes and synthesizes unit.
For tower 4 close to normal pressing operation, feedstock quality flow is about 1 feed rate 1/3-1/2 of tower.Ionic liquid is then from tower
The appropriate location of 4 rectifying sections adds in.Rectifying section reflux ratio 0.5-5.0, dimethoxym ethane concentration is more than 97% in overhead distillate, first
Determining alcohol is less than 0.5-0.9%, can be recycled to polymethoxy dimethyl ether and catalyze and synthesize unit.With ionic liquid for water
With the selective dissolution of methanol, extraction is all entered by ion liquid abstraction into distillation system, almost all of water and methanol
Take the bottom of towe of rectifying column.Ion liquid abstraction liquid then heated flash tank 5 flash-evaporation dehydration higher into vacuum degree, piptonychia
Alcohol.According to its composition, the synthesis unit of the recyclable raw material dimethoxym ethane to synthesis polymethoxy dimethyl ether after condensed.Due to
Ionic liquid is non-volatile, non-combustible, almost without loss during as extractant Reusability.
With it is existing, catalyze and synthesize using dimethoxym ethane and concentrated formaldehyde aqueous solution as raw material, under acidic catalyst effect it is poly-
The mixture of reaction products isolation technics of methoxyl group dimethyl ether is compared, and said program of the invention has the following advantages that：
1st, using rectifying as few as possible and extractive distillation column, point of the product mixtures with nearly 20 components is realized
From；
2nd, a variety of different purpose products schemes are adapted to.For example, high-purity PODE2 and PODEn (n=are produced simultaneously
3-5) or PODEn (n=3-6) and PODE2 and two class of PODEn (n=3-5) or PODEn (n=3-6) are adjusted according to the market demand
The ratio of purpose product；
3rd, since the water in product mixtures and methanol are highly soluble in selected ionic liquid, but ionic liquid is in itself hardly
Volatilization is a kind of extractant for cleaning very much and not losing in use.Due to being detached by the rectifying of tower 1, into extraction
The flow of rectifying column 4 is taken to be greatly lowered compared with entering tower 1, but is contained into almost complete in distillation system
Portion's moisture, This reduces both the flows of dehydration liquid, are also beneficial to inhibit to continue water participation, formic acid in separation process
The side reaction of catalysis and acid, water exist simultaneously caused electrochemical corrosion.
4th, to economize on resources and simplify product mixtures separation process as target, related stream stock after being detached according to each rectifying column
Composition, other than purpose product stream stock, all stream stocks are respectively recycled back into polymethoxy dimethyl ether and are urged with dimethoxym ethane
Unit is combined to, almost without the wasting of resources.
5th, it is possible that the flow of depickling processing logistics is minimized.
Description of the drawings
Fig. 1：Rectifying separation process figure.
B1：Conventional rectification tower 1, B2：Conventional rectification tower 2, B3：Conventional rectification tower 3, B4：Extraction distillation column, B5：Flash tank
FEED:Product mixtures, 4：1 fixed gas of tower, VAP1：1 distillate of tower, BOT1：1 bottom liquid of tower
VAP2：2 distillate of tower, BOT2：2 bottom liquid of tower
VAP3：3 distillate of tower, BOT3：3 bottom liquid of tower
IL:Ion liquid abstraction agent, VAP4：4 distillate of tower, BOT1：4 bottom liquid of tower, VAP5：Flash gas, 6：It flashes cold
Lime set
IL-REC：The extractant of methanol removal and water
Specific embodiment
Embodiment 1
Separation process as shown in Figure 1.By polymethoxy dimethyl ether PODEn (n=2-10), unreacting material dimethoxym ethane,
The compositions such as formaldehyde and its trimer and hydrate, the water brought into raw material, by-product carbinol, methyl formate, formic acid are detached
Material enters the rectifying column 1 that number of theoretical plate is 30-60, mass flow 1000kg/h at 80-100 DEG C of temperature.
The operating pressure of rectifying column 1 is about 0.1MPa, and reflux ratio 1.5-5.0, bottom temperature is about 115-125 DEG C.Top
Produced Liquid 360-430kg/h is sent to extractive distillation column 4, and the composition overwhelming majority is light component, for example, methyl formate is about
1.5%, more than 80% dimethoxym ethane, more than 8% methanol, into the almost all of water of distillation system, concentration is about 0.4%,
Containing a small amount of metaformaldehyde, methylene glycol MG1 and hemiacetal HF1, but without formic acid.Bottom of towe Produced Liquid is at 115-125 DEG C of temperature
It send to the rectifying column 2 of number of theoretical plate 30-50, mass flow 570-640kg/h.
The operating pressure 0.03-0.06MPa of rectifying column 2, reflux ratio 1.5-5.0, bottom temperature are about 135-155 DEG C.Top
Portion's Produced Liquid is about 300-340kg/h, and composition is mainly PODE2, remaining for a small amount of PODE3, trimerization first up to nearly 70%
Aldehyde, methylene glycol MG1, dimethoxy methylene glycol MG2 and dimethoxy hemiacetal HF2.Reaction member can be recycled into change
Kind reactor feed composition, and then improve the selectivity and yield of PODEn (n=3-6) in reaction process.Bottom of towe Produced Liquid is in temperature
It is sent at 135-155 DEG C of degree to the rectifying column 3 of number of theoretical plate 35-65, mass flow 270-300kg/h.
The operating pressure 0.003-0.005MPa of rectifying column 3, reflux ratio 1.5-5.0, bottom temperature are about 160-185 DEG C.
Overhead extraction liquid is about 205-270kg/h, composition mainly PODEn (n=3-6), about 99%, three polymethoxy hemiacetals
HF3, about 0.6%, it is remaining be 0.4% or so formic acid.It is handled by depicklings such as conventional weak-base anion-exchange resin absorption,
Obtain purpose product.Bottom of towe Produced Liquid mass flow 30-65kg/h, composition is mainly PODEn (n=7-10), reacted
It is recycled to after raw material dilution and catalyzes and synthesizes unit and form with improving reactor feed, and then PODEn (n in raising reaction process
=3-6) selectivity and yield.
Embodiment 2
Separation process as shown in Figure 1.1 top of tower is produced, containing more than 80% dimethoxym ethane, more than 8% methanol is gone back
There is the liquid mixture 360- of a small amount of PODE2, metaformaldehyde, hemiacetal HF1 and nearly all moisture into distillation system
430kg/h is sent to the extractive distillation column 4 of number of theoretical plate 20-50, and extracting rectifying is carried out by the use of ionic liquid as extractant.Ionic liquid
Body flow 150-270kg/h.
The operating pressure of extractive distillation column 4 is about 0.1MPa, and reflux ratio 1.5-4.5, bottom temperature is about 82-95 DEG C.Tower
It is about 300-350kg/h to push up condenser Produced Liquid, and wherein dimethoxym ethane is about 98%, and methyl formate is about 1.2%, and methanol is about
0.80%.It can be recirculated back to and catalyze and synthesize unit.Into the nearly all moisture and nearly 92% methanol of distillation system
Then produced with cleaning solvent ionic liquid and a small amount of hemiacetal HF1, metaformaldehyde and PODE2 from bottom of towe.The matter of bottom of towe Produced Liquid
Flow 210-350kg/h is measured, is flashed under about 0.01-0.015MPa after being heated to 130-160 DEG C, steam flow is only about
For 60-80kg/h, including methanol all in bottom of towe Produced Liquid, water, hemiacetal HF1, metaformaldehyde and PODE2.By this
Dimethoxym ethane, which is recycled back into, after stock steam condensation catalyzes and synthesizes unit.Since ionic liquid is non-volatile under flash temperature,
It can easily be realized in flash process with other organic matters and be separated and recycle.
Embodiment 3
Separation process as shown in Figure 1.2 bottom Produced Liquid of tower is sent at 140-155 DEG C of temperature to number of theoretical plate 35-45's
Rectifying column 3, mass flow 270-320kg/h.
The operating pressure 0.003-0.005MPa of rectifying column 3, reflux ratio are about 2.0, and bottom temperature is about 160-185 DEG C.
Overhead extraction liquid is about 225-255kg/h, and it is mainly PODEn (n=3-6) to form, and about 98.6%, three polymethoxies half contract
Aldehyde HF3 is about 1.0%, it is remaining be 0.4% or so formic acid.It is handled by depickling to get to purpose product.Bottom of towe Produced Liquid quality
Flow 45-65kg/h, composition are mainly PODEn (n=7-10), and polymethoxy diformazan is recycled to after reacted raw material dilution
Ether catalyzes and synthesizes unit and is formed with improving reactor feed, so improve reaction process in PODEn (n=3-6) selectivity with
Yield.
Claims (11)
1. a kind of process for synthesizing the separation of polymethoxy dimethyl ether reaction product, using dimethoxym ethane and concentrated formaldehyde aqueous solution as original
The product of material catalysis reaction synthesis polymethoxy dimethyl ether (PODEn, n=2-10) is starting material, it is characterised in that：Reaction production
Object (n=2-10) containing PODEn, methylene glycol MG1 that dimethoxym ethane, formaldehyde monomers, formaldehyde and water are combined into, polymethoxy methylene glycol
The reaction product mixing of MGn, a small amount of moisture, hemiacetal HF1, polymethoxy hemiacetal HFn, methanol, formic acid and methyl formate
Object separation is in three conventional rectification tower towers (B1), tower (B2) and tower (B3), an ion liquid abstraction rectifying column (B4) with detaching
It recycles and is completed in the flash tank (B5) of ionic liquid and the device of associated satellite equipment composition.
2. the process of synthesis polymethoxy dimethyl ether reaction product separation according to claim 1, it is characterised in that：
It is required according to the difference of products scheme, obtains PODEn (n=3-6) more than purity 99.5% (mass percent), its in product
Remaining part point predominantly application performance and polymethoxy hemiacetal HF3 similar in PODE3.High-purity PODE2 can also be produced simultaneously
With PODEn (n=3-6).
3. the process of synthesis polymethoxy dimethyl ether reaction product separation according to claim 1 or 2, feature exist
In：Three conventional rectification tower towers (B1), tower (B2) and tower (B3) operate respectively close under normal pressure, negative pressure and higher vacuum；
One ion liquid abstraction rectifying column (B4) is close to normal pressing operation, and ion liquid abstraction rectifying tower bottom Produced Liquid is in 130-
Flash distillation removes the whole moisture and methanol into distillation system in vacuum flasher (B5) at a temperature of 150 DEG C, recycles ion
Liquid simultaneously recycles.
4. the process of the synthesis polymethoxy dimethyl ether reaction product separation according to claims 1 or 2 or 3, special
Sign is：Mixture of reaction products is separated into two stream stocks of tower top and bottom of towe, overhead vapor phase stream stock in conventional rectification tower (B1)
After the condensation of water cooled condenser, including dimethoxym ethane, methylene glycol MG1, hemiacetal HF1, methanol, methyl formate, metaformaldehyde, water and
In the liquid phase of minute quantity PODE2, reflux of the part as conventional rectification tower 1, quantity is about distillation system charging total amount 2/5-
2/7 another part introduces ion liquid abstraction rectifying column (B4) dehydration, separating methanol；Contain polymethoxy dimethyl ether PODE2-
10th, the mixture of methylene glycol MG1, dimethoxy methylene glycol MG2, dimethoxy hemiacetal HF2, metaformaldehyde and formic acid etc. is from
One conventional rectification tower bottom of towe introduces conventional rectification tower 2 as charging.
5. the process of the synthesis polymethoxy dimethyl ether reaction product separation according to one of Claims 1-4, special
Sign is：The ion liquid abstraction rectifying and dewatering for being about distillation system charging total amount 1/2-1/8 with quantity, separating methanol simultaneously make first contract
Aldehyde further concentrates, and in the overhead condensation liquid of extractive distillation column (B4), at concentrations up to more than 97%, water content about exists dimethoxym ethane
20PPM hereinafter, methanol content about in 0.6-0.9% hereinafter, which part as reflux, quantity be about distillation system charging total amount
Another part be recycled to polymethoxy dimethyl ether and catalyze and synthesize unit.
6. the process of the synthesis polymethoxy dimethyl ether reaction product separation according to one of claim 1 to 5, special
Sign is：In conventional rectification tower (B2), charging is separated into two stream stocks of tower top and bottom of towe：Overhead vapor phase is condensed through complete condenser
Afterwards, partly as reflux, total amount is about another part of distillation system charging total amount 1/3-1/5, and PODE2 concentration is in 60-
70%, simultaneously containing a small amount of PODE3, metaformaldehyde, methylene glycol MG1, dimethoxy methylene glycol MG2 and dimethoxy hemiacetal
The mixture of HF2 is recycled to polymethoxy dimethyl ether and catalyzes and synthesizes unit, to improve its feed composition, improves purpose product
The selectivity and yield of PODE3-6；Quantity is about distillation system total feed 1/3-1/5, contains polymethoxy dimethyl ether
The bottom liquid mixture of PODE3-10, three polymethoxy hemiacetal HF3 and formic acid introduce conventional rectification tower (B3) as charging.
7. the process of the synthesis polymethoxy dimethyl ether reaction product separation according to one of claim 1 to 6, special
Sign is：In conventional rectification tower (B3), the charging including PODE3-10 and minute quantity formic acid is separated into tower top and bottom of towe two
A stream stock, overhead vapor phase obtain more than 99.5% purity after complete condenser condenses, PODE3-5 or PODE3- containing a small amount of formic acid
6, high-purity purpose product PODE3-5 or PODE3-6 are can obtain after depickling；Bottom of towe is based on PODE5-8 or PODE6-8, is contained
There is the mixture of a small amount of PODE9-10, be recycled to after the dilution of the reaction raw materials such as the dimethoxym ethane of metering and catalyze and synthesize unit, with
Improve its feed composition, improve the selectivity and yield of purpose product PODE3-6.
8. the process of the synthesis polymethoxy dimethyl ether reaction product separation according to one of claim 1 to 7, special
Sign is：Ionic liquid used in extracting rectifying includes but not limited to following：Cation is imidazoles, pyridines or quaternary ammonium salt
Deng anion is bis-trifluoromethylsulfoandimide, tetrafluoroborate, hexafluoro-phosphate radical, acetate or dithyl sulfate etc..
9. the process of the synthesis polymethoxy dimethyl ether reaction product separation according to one of claim 1 to 8, special
Sign is：Used conventional rectification tower and extractive distillation column are packed tower or plate column, optimally, using packed tower.
10. catalyze and synthesize the separation of polymethoxy dimethyl ether (PODEn) product mixtures according to one of claim 1 to 9
Process, it is characterised in that：The operating pressure of three conventional rectification towers (B1), (B2) and (B3) is respectively 0.15-
0.10MPa, 0.03-0.06MPa and 0.003-0.006MPa, the operating pressure of ion liquid abstraction rectifying column is 0.09MPa-
0.10MPa；Conventional rectification tower 1 is the liquid feedstock close to boiling point, can also vapour/liquid mixture charging；Other each towers are close
The liquid phase feeding of boiling point.
11. the process of the synthesis polymethoxy dimethyl ether reaction product separation according to one of claims 1 to 10,
It is characterized in that：It can be with extended products scheme to can either produce by adjusting operating parameter
PODEn (n=3-5 or n=3-6), can also produce environment-friendly type solvent PODE2 simultaneously；Or by the second conventional rectification tower
Overhead product is only the conventional rectification tower of above-mentioned first rectifying column 1/3 or so through an other treating capacity, according to boiling as raw material
Journey separates PODE2, HF2 and light component MG1, HF1 and heavy constituent MG2, extraction high-purity PODE2, HF2 as solvent, gently,
Heavy component is recyclable to catalyzing and synthesizing unit.
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