CN1049212C - Improved synthetic method of dialkyl carbonate - Google Patents
Improved synthetic method of dialkyl carbonate Download PDFInfo
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- CN1049212C CN1049212C CN94112211A CN94112211A CN1049212C CN 1049212 C CN1049212 C CN 1049212C CN 94112211 A CN94112211 A CN 94112211A CN 94112211 A CN94112211 A CN 94112211A CN 1049212 C CN1049212 C CN 1049212C
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C68/00—Preparation of esters of carbonic or haloformic acids
- C07C68/06—Preparation of esters of carbonic or haloformic acids from organic carbonates
- C07C68/065—Preparation of esters of carbonic or haloformic acids from organic carbonates from alkylene carbonates
Abstract
The present invention discloses an improved method for synthesizing dialkyl carbonate, which mainly comprises three processes, namely reaction rectification, extractive rectification and diester separation, wherein the reaction rectification process is mainly carried out in a reaction section of a rectification tower, and all alkenyl carbonate can be converted into dialkyl carbonate. The present invention has the advantages of high conversion rate(can reach above 99.8%), low energy consumption, simple technology, etc.
Description
The invention belongs to the chemical reaction engineering field, particularly relate to a kind of synthetic method of alkyl carbonate.
As everyone knows, dialkyl carbonate (mainly being meant methylcarbonate, diethyl carbonate) is that a kind of organic synthesis of great use is originally middle, not only can synthesize many organic chemical industry's products, all right replacement sulfur dimethyl phthalate (highly toxic product) is as alkylating agent, substitute phosgene (highly toxic product) as the carbonylation agent, but the purposes of its maximum is as gasoline dope, can improves the octane value and the oxygen level of gasoline, make white gasoline, thereby have extensive market prospects.
1972, U.S. Pat P3642858 (hereinafter to be referred as the A patent) disclosed this a kind of " with the method for propylene carbonate acid with the methyl alcohol Synthesis of dimethyl carbonate ", but there are three big problems in this method:
(1) transesterification reaction of system is a reversible, and the transformation efficiency of its molecular balance is very low again;
(2) resultant of reaction methylcarbonate and material benzenemethanol form azeotrope, cause to separate and go up difficulty;
(3) by product propylene glycol and raw material propylene carbonate also form azeotrope, cause the difficulty in the separation equally.
For this reason, 1974, U.S. Pat P3803201 (hereinafter to be referred as the B patent) made improvement to the A patent, proposed:
(1) adopts distillation method, the azeotrope steaming of methylcarbonate in the reaction system and methyl alcohol is reacted divided by strengthening, improve the transformation efficiency of transesterification reaction;
(2) adopt freezing rectification method, the azeotrope of the methylcarbonate that steams and alcohol is carried out freezing, (deep cooling is to-70 ℃) carry out rectifying separation then, extract methylcarbonate respectively and reclaim methyl alcohol.
Obviously, this method energy consumption is very big, and the transformation efficiency less than 60% of transesterification reaction, so production cost is also very high.
The Zhang Shaogang of China and Luo Youshou (seeing " gas chemical industry " the 16th the 3rd phase of volume, 1991) were the raw material Synthesis of dimethyl carbonate with propylene carbonate and methyl alcohol once, and B patent and technology have been carried out checking research, found:
(1) transesterification reaction is mainly carried out in the tower still, and contains five components (two raw materials, two azeotropes, a homogeneous catalyst) in the tower still at least, has not only brought very big difficulty to separation, and has influenced the raising of transesterification reaction transformation efficiency.
(2) in order to improve transformation efficiency, must the azeotrope of methylcarbonate and methyl alcohol be distilled (can make transformation efficiency be increased to 80%) under up to 8～10 condition in reflux ratio, so energy consumption is very big, as reducing reflux ratio, then the azeotrope amount of steaming is few, and transformation efficiency is with regard to less than 60%.
As seen, above-mentioned prior art does not also find a kind of suitable method further to improve transformation efficiency.
1987, U.S. Pat P4691041 (hereinafter to be referred as the C patent) improved A patent, B patent again, proposed;
(1) adopts strong basic ion exchange resin to make the catalyzer of esterification, solve the separation problem of catalyzer;
(2) adopt the compression rectification method, the methylcarbonate that Reaction Separation is obtained and the azeotrope of methyl alcohol give separation and Extraction respectively;
(3) adopt hydrolysis method, the method that the ethylene (propylene) carbonate in the azeotrope of by product second (or third) glycol and ethylene (propylene) carbonate is hydrolyzed into second (or third) diacid and yellow soda ash is handled.
Obviously, this method technology is complicated, operation inconvenience, and raw-material utilization ratio low (because of the raw material ethylene (propylene) carbonate is hydrolyzed), and transformation efficiency does not also improve.
1988, day disclosure is speciallyyed permit clear 63-205101, the method of a kind of separating dimethyl carbonate and methyl alcohol azeotrope has been proposed, adopt benzene and methyl alcohol to form the new azeotrope lower than the constant boiling point of methyl alcohol and methylcarbonate, thereby isolate methylcarbonate, methyl alcohol water in the new azeotrope extracts, and reclaims by distilling then.Though this method has solved the separation problem of methyl alcohol and methylcarbonate preferably, but owing to must reclaim methyl alcohol with distillation, still need much energy consumption, and make product methyl-carbonate also contain moisture content in the aqueous methanol retrieval system, influence quality product, so this method is also undesirable, and do not relate to the raising problem of transformation efficiency among the patent A.
In sum, as seen: up to the present, prior art is not also properly settled three related big problems of patent A, that is:
(1) how to take suitable technical measures, make ethylene (propylene) carbonate all change into dialkyl carbonate, promptly the ethylene (propylene) carbonate transformation efficiency reaches 100% during transesterification reaction;
(2) how to take suitable technical measures, under less energy-consumption, separate to obtain methyl alcohol (or ethanol) and dialkyl carbonate azeotrope, then again under less energy-consumption, the garden completely solves the separation problem of methyl alcohol (or ethanol) and dialkyl carbonate;
(3) how to take suitable technical measures, under less energy-consumption, solve the purification problem of still bottom product.Obviously when the technical measures garden of (1) completely solved, then the separation of still bottom product just became easier.
The objective of the invention is to overcome patent A existing three big problems comprehensively, a kind of synthetic method of improved dialkyl carbonate has been proposed, can make ethylene (propylene) carbonate all change into dialkyl carbonate, and separation obtain dialkyl carbonate product and by product second (or third) glycol under less energy-consumption.Design of the present invention is such:
(1) according to the principle of reactive distillation, make transesterification reaction in conversion zone, carry out with separating all (rather than resembling and reacting youngster the forefathers and in the tower still, carry out, carry out and be separated in the tower section), when being generated, reaction product removes with regard to separated, thereby constantly disequilibrate, increased the impellent of reaction, reaction is developed to the direction that helps generating product, made the raw material ethylene (propylene) carbonate all change into product at last.
(2) by improving the feed rate ratio of raw material " alcohol and ethylene (propylene) carbonate ", it is dialkyl carbonate fat and pure mixture that reaction fractionating tower top is obtained, rather than azeotrope, thereby can under the condition of low reflux ratio, carry out rectifying separation, thus cut down the consumption of energy widely.
(3) according to the principle of extracting rectifying, alcohol and dialkyl carbonate ester mixture " steam " that the reactive distillation top of tower comes out are directly sent in the extractive distillation column, utilized corresponding ethylene (propylene) carbonate to make extraction agent, dialkyl carbonate is extracted.At the bottom of tower, obtain extraction phase-dialkyl carbonate and carbon ester alkene ester mixture (be called for short two ester mixtures, down with), obtain extracting phase-alcohol at cat head and can directly return reaction fractionating tower and recycle.Two ester mixtures of gained enter in the diester knockout tower, and through fractionation, cat head can obtain purity and reach the above dialkyl carbonate product of 99.8% (wt), can obtain the ethylene (propylene) carbonate of purity＞99% at the bottom of the tower, can return in the extractive distillation column to recycle.Because the boiling point between the diester has a long way to go, therefore separating is easily.
(4) Fan Ying by product second (or third) glycol, because ethylene (propylene) carbonate almost all is converted to dialkyl carbonate in the system, therefore the ethylene (propylene) carbonate that only contains trace in by product second (or third) glycol, and a spot of catalyzer (sodium alkoxide) and alcohol, its separation is to be relatively easy to, it can be purified by the stripping section that reaction fractionating tower is divided into, and gives off purity and reaches second (or third) glycol more than 99%.The present invention also is achieved in that
Method of the present invention comprises that mainly reactive distillation, extracting rectifying and diester separate three technological processs.
(1) in a reaction fractionating tower of mainly forming by tower still, stripping section, conversion zone, rectifying section, reaction mass ethylene (propylene) carbonate and enter reaction fractionating tower from conversion zone top with a small amount of pure dissolved catalyzer sodium alkoxide, excessive greatly raw alcohol (methyl alcohol or ethanol) enters the reaction fractionating tower from the conversion zone bottom, two materials are made counter current contact in conversion zone, transesterification reaction is carried out on the limit, separate on the limit, lower boiling product dialkyl carbonate is constantly gasified remove from system.Said reaction fractionating tower is a tray column.By conversion zone, make the reaction mass ethylene (propylene) carbonate all change into dialkyl carbonate.Be advanced in the rectifying section on reaction fractionating tower top on the mixing steam of excessive greatly alcohol (methyl alcohol or ethanol) and dialkyl carbonate, under the condition of reflux ratio 0.6～1.0, the ethylene (propylene) carbonate further refining and recovery is wherein carried secretly, the ethylene (propylene) carbonate that reclaims drops to and continues to participate in reaction in the reactive distillation section, dialkyl carbonate after refining and pure mixing steam (except the part that refluxes) directly advance in the extractive distillation column.Byproduct of reaction second (or third) glycol, and the ethylene (propylene) carbonate of trace, a spot of sodium alkoxide and alcohol then are advanced in the stripping section of reaction fractionating tower down, behind stripping section recovery ethylene (propylene) carbonate, sodium alkoxide and alcohol wherein, second (or third) glycol that obtains purity＞99% enters in the tower still, and discharge quantitatively outside the tower still, and then, just can be used as product and sell by after further rectified purified.The working pressure of reaction fractionating tower is 90～110KPa operation, should operate under normal pressure.The molar ratio of alcohol/ethylene (propylene) carbonate can be chosen in 6～10 scopes.When being raw material with methyl alcohol, molar ratio is preferably 8～10; When being raw material with ethanol, molar ratio is preferably 6～8.
(2) in an extractive distillation column of mainly forming by tower still, stripping section, extraction section, rectifying section, come from the dialkyl carbonate of reaction fractionating tower and the mixing steam of alcohol (methyl alcohol or ethanol) and enter the bottom of the extraction section of extractive distillation column, the extraction agent ethylene (propylene) carbonate then enters the tower from the top of extraction section, the two carries out counter current contact in extraction section, dialkyl carbonate is all entered in the extraction agent.Be advanced on the methyl alcohol of raffinate in the rectifying section of tower, under the condition of reflux ratio 0.6～1.2, further refining the recyclable purity that obtains is greater than 99% above methyl alcohol except that behind the ethylene (propylene) carbonate of deentrainment, and the methyl alcohol of recovery returns in the reaction fractionating tower and recycles.Extraction phase is the mixture (being called for short two ester mixtures, down together) of ethylene (propylene) carbonate and dialkyl carbonate, descending stripping section by extractive distillation column, after removing the methyl alcohol of wherein carrying secretly, enter again in the tower still, discharge the tower still then quantitatively, and enter in the diester knockout tower.Said extractive distillation column also is a kind of tray column.Extraction agent ethylene (propylene) carbonate consumption can be in extraction agent and mixed steam the ratio 1～2 of mole of methyl alcohol in the choosing of scope.The trim the top of column ratio should get 0.8～1.0.The extracting rectifying process should be carried out under normal pressure, but also can operate under negative pressure, as operating under pressure 70～101KPa.
(3) in a diester knockout tower of mainly being formed by tower still and fractionation section, two ester mixtures that come from extracting rectifying Tata still enter the middle part of the fractionation section of diester knockout tower, through fractionation, can obtain purity greater than 99.8% (wt) alkyl carbonate product at cat head, the recyclable purity that obtains is greater than 99.9% (wt) ethylene (propylene) carbonate in the tower still, and the ethylene (propylene) carbonate of recovery returns in the extractive distillation column and recycles.By the tower still by outer heat provide fractionation process required whole energy.The trim the top of column ratio is 0.4～0.6, and tower still temperature is 160-180 ℃, should operate under negative pressure, and suitable working pressure is 30～50KPa.
Further illustrate content of the present invention below in conjunction with drawings and Examples, but these embodiment do not limit protection scope of the present invention.
Accompanying drawing 1 is the process flow diagram of production dialkyl carbonate of the present invention
Wherein:
F-reaction fractionating tower
F
1-tower still, F
2-stripping section,
F
3-conversion zone, F
4-rectifying section,
1-raw alcohol inlet, 2-raw material ethylene (propylene) carbonate inlet,
3-mixed gas outlet, 4-phegma inlet,
The outlet of 5-second (or third) glycol.
T-extractive distillation column
T
1-tower still, T
2-stripping section,
T
3-extraction section, T
4-rectifying section,
6-gas mixture inlet, 7-alcohol (gas) outlet,
8-phegma inlet, 9-extraction agent inlet,
10-diester mixture outlet, 11-alcohol (liquid) transfer lime.
D-diester knockout tower
D
1-tower still, D
2-fractionation section,
12-diester mixture inlet, the outlet of 13-dialkyl carbonate
14-phegma inlet, the outlet of 15-extraction agent.
C
1, C
2, C
3-condenser
B
1, B
2, B
3-pump
E-vapour liquid separator
16-dialkyl carbonate inlet,
17-dialkyl carbonate products export,
The outlet of 18-tail gas.
In reaction fractionating tower F:
The alcohol that comes from storage tank pumps into conversion zone F by entrance 1 after metering3The bottom, enter conversion zone F by entrance 2 after metering respectively from the ethylene (propylene) carbonate of storage tank and with the catalyst sodium alkoxide of alcohol dissolving preparation3Top, the two under the effect of catalyst sodium alkoxide at conversion zone F3In carry out ester exchange reaction and separate. Instead Answer the rectifying section F that passes through on the mixed vapour (be called for short gaseous mixture, lower with) of product dialkyl carbonate and alcohol4After the ethylene (propylene) carbonate material of wherein carrying secretly is removed in recovery, discharged by outlet 3, wherein partially mixed gas is without cold Among the T, partially mixed gas is wanting according to the required reflux ratio of tower operation then under the solidifying directly importing extractive distillation column Ask, through condenser C, after the condensation, returned the cat head of reaction fractionating tower by phegma entrance 4. The reaction by-product Thing second (or third) glycol and the ethylene (propylene) carbonate of carrying secretly, pure and mild sodium alkoxide etc. then are advanced into down stripping section F2In, through carry heat up in a steamer refining after, obtain purity greater than the second more than 99% (or third) glycol, enter tower reactor F1In, and discharge outside the still from exporting 5 quantitatively. In extractive distillation column T:
The gaseous mixture that comes from reaction fractionating tower F top enters extraction section T through entrance 63The bottom, the extractant ethylene (propylene) carbonate that comes from storage tank (or diester fractionating column tower reactor) enters extraction section T by entrance 93Top, the two is at extraction section T3In carry out counter-current extraction, dialkyl carbonate is extracted into (letter in the ethylene (propylene) carbonate Claim two ester admixtures, lower same). The descending stripping section T that enters of two ester admixtures2In, except behind the alcohol of deentrainment, enter again tower reactor T1In, discharge outside the still through exporting 10 quantitatively then, and by pump B2Delivering to diester separates Among the tower D. Be advanced into rectifying section T on the raffinate phase (alcohol)4In, reclaim except behind the ethylene (propylene) carbonate of deentrainment, obtain purity greater than 99% alcohol, discharge cats head through exporting 7, again through condenser C2After the condensation, a part Return the top of extractive distillation column by the reflux ratio requirement through phegma entrance 8, another part alcohol is then through carrier pipe 11 deliver in the reaction fractionating tower and recycle. In diester knockout tower D:
From two ester admixtures of extractive distillation column by pump B2Pump into distillation stage D through entrance 122The middle part, Under pressure 30～50KPa, carry out fractionation. The dialkyl carbonate that fractionation obtains is up, through exporting 13 rows Go out cat head, by condenser C3After the condensation, the reflux ratio requirement warp a when part operates by the diester splitter column Entrance 14 returns the top of diester knockout tower, and another part then enters gas-liquid separator E through entrance 16 In, after gas-liquid separation, to be discharged by outlet 17, the tail gas after the gas-liquid separation then enters very by exporting 18 Do-nothing system. The ethylene (propylene) carbonate that shunting obtains then is advanced into down tower reactor D1In, discharge outside the still, by pump B through exporting 15 quantitatively then3Pump in the extractive distillation column through entrance 9 and to recycle.
Embodiment 1
In a process unit of mainly being formed by reaction fractionating tower, extractive distillation column and diester knockout tower, drop into raw material propylene carbonate and methyl alcohol, under the effect of catalyzer sodium methylate, produce methylcarbonate.
Said reaction fractionating tower is 1000 millimeters of diameters, high 18000 millimeters tray column, in establish 36 of column plates, wherein: conversion zone is 30, stripping section is 5, rectifying section is 1.
Said extractive distillation column is 1000 millimeters of diameters, high 15000 millimeters tray column, in establish 23 of column plates, wherein: extraction section is 15, stripping section is 7, rectifying section is 1.
Said diester knockout tower is 800 millimeters of diameters, high 2000 millimeters tray column, in establish 3 of column plates, entirely in the fractionation section.Reaction fractionating tower is operated under following operating mode:
Material benzenemethanol enters the bottom of conversion zone with the speed of 1078.4kg per hour, the speed of the per hour 382kg of raw material propylene carbonate enters the top of conversion zone, the mol ratio of the two is 9, catalyzer sodium methylate (be dissolved in earlier in the methyl alcohol and form the solution that contains sodium methylate 42%) enters the top of conversion zone with the speed of 4.55kg per hour, provides reactive distillation processes required whole energy by the tower still by outer heat.The trim the top of column ratio is 0.75, and tower still temperature is 185～190 ℃, and working pressure is a normal pressure.Cat head gas mixture (nail alcohol and methylcarbonate gas mixture, down together) with the per hour speed discharge of 1175.7kg, do not comprise quantity of reflux, it is without condensation, directly import in the extractive distillation column, the ratio of components of gas mixture is: methanol content is that 71.4% (wt), DMC addition are 28.6% (wt).Obtaining content in the tower still is the propylene glycol by product of 99.2% (wt).(all the other are propylene carbonate 0.12% (wt), methyl alcohol 0.01% (wt), sodium methylate 0.67% (wt)), through further refining and reclaim sodium methylate after, propylene glycol can be used as the commercially available prod, but recycles in the sodium methylate retrieval system of recovery.Is 99.9% with the propylene carbonate for the benchmark transformation efficiency.Extractive distillation column is operated under following operating mode:
Gas mixture enters the bottom of extraction section with the speed of 1175.7kg per hour, extraction agent is a propylene carbonate, enter the top of extraction section with the speed of 4015kg per hour, the mol ratio of the methyl alcohol in extraction agent and the gas mixture is 1.5, provide distillation operation needed whole energy by the tower still by outer heat, the trim the top of column ratio is 0.8, and tower still temperature is 160～180 ℃, operates under normal pressure.Obtain the methyl alcohol of purity 99.2% in recovered overhead, discharge with the speed of 834.4kg per hour.The methyl alcohol that reclaims can directly return in the reaction fractionating tower and recycle.The mixture that obtains propylene carbonate and methylcarbonate at (in the tower still) at the bottom of the tower (is called for short two ester mixtures, down together), its ratio of components is: the propylene carbonate ester content is 92.25% (wt), DMC addition is 7.74% (wt), also has a spot of methyl alcohol, it is discharged with the speed of 4352.3kg per hour, and imports in the diester knockout tower.The diester knockout tower is operated under following operating mode:
Two ester mixtures enter the middle part of fractionation section with the speed of 4352.3kg per hour, by tower still D
1Provide the fractionation process energy needed by outer heat, trim the top of column is than 0.5, and tower still temperature is 160～180 ℃, and working pressure is 30～50KPa.Cat head per hour can obtain the methylcarbonate 337.5kg of purity greater than 99.8% (wt), (in the tower still) per hour recyclable propylene carbonate 4014.8kg that obtains purity greater than 99.95% (wt) at the bottom of the tower, the propylene carbonate of recovery returns in the extractive distillation column and recycles.The loss of extraction agent is less than 0.005%.
Embodiment 2
In a process unit of mainly being formed by reaction fractionating tower, extractive distillation column and diester knockout tower, drop into material carbon vinyl acetate and methyl alcohol, under the effect of catalyzer sodium methylate, produce methylcarbonate.
Said reaction fractionating tower, extractive distillation column, diester knockout tower are all described with embodiment 1.Reaction fractionating tower is operated under following operating mode:
Material benzenemethanol enters the bottom of conversion zone with the speed of 1078.4kg per hour, the material carbon vinyl acetate enters the top of conversion zone with the speed of 329.6kg per hour, the mol ratio of the two is 9, catalyzer also is a sodium methylate, it enters the top of conversion zone with the speed of 4kg per hour, provides reactive distillation processes required whole energy by the tower still by outer heat, and the trim the top of column ratio is 0.75, tower still temperature is 185～190 ℃, and working pressure is a normal pressure.Cat head gas mixture (its ratio of components is with embodiment 1), directly imports in the extractive distillation column without condensation with the per hour speed discharge (disregarding quantity of reflux) of 1175.7kg.Obtaining content in the tower still is that (all the other are NSC 11801 0.25% to 98.8% (wt) ethylene glycol by product, methyl alcohol is 0.017%, sodium methylate is 0.93%), after further making with extra care and reclaim sodium methylate wherein, ethylene glycol can be used as the commercially available prod, but recycles in the sodium methylate retrieval system of recovery.The transformation efficiency that with the NSC 11801 is benchmark is 99.8%.
The operating mode of extractive distillation column is except extraction agent is NSC 11801, and the rest working conditions condition is all with embodiment 1.NSC 11801 enters the top of extraction section with the speed of 3464.3kg per hour, and the mol ratio of methyl alcohol also is 1.5 in extraction agent and the gas mixture.Obtaining purity in recovered overhead is 99.3% methyl alcohol, discharges with the speed of 844.7kg per hour.The methyl alcohol that reclaims directly returns in the reaction fractionating tower and recycles.The mixture that obtains NSC 11801 and methylcarbonate at (in the tower still) at the bottom of the tower (is called for short two ester mixtures, down together) its ratio of components is: NSC 11801 91.28%, methylcarbonate 8.7% (wt), all the other are a spot of methyl alcohol, with the per hour speed discharge of 3795kg, and import in the diester knockout tower.
The working condition of diester knockout tower is the 3795kg/hr except the ingress rate of two ester mixtures, and all the other conditions are all with embodiment 1.Per hour can obtain purity greater than 99.8% methylcarbonate product 330.8kg at cat head, be 99.96% NSC 11801 3464.2kg in the per hour recyclable purity that obtains of tower still.The NSC 11801 that reclaims is then returned in the extractive distillation column and is recycled.The loss of extraction agent is less than 0.005%.
Embodiment 3
In a process unit of mainly being formed by reaction fractionating tower, extractive distillation column and diester knockout tower, drop into raw material propylene carbonate and ethanol, under the effect of catalyzer sodium ethylate, produce diethyl carbonate.
Said reaction fractionating tower is 600 millimeters of diameters, high 15000 millimeters tray column, in establish 33 of column plates.Wherein: conversion zone is 25,7 of stripping sections, 1 of rectifying section.
Said extractive distillation column is 600 millimeters of diameters, high 12000 millimeters tray column, in establish 20 of column plates, wherein: extraction section is 11,8 of stripping sections, rectifying section are 1.
Said diester knockout tower is 500 millimeters of diameters, high 2000 millimeters packing tower, 1200 millimeters of the bed stuffing heights of fractionation section.Reaction fractionating tower is operated under following operating mode:
Feed ethanol enters the bottom of conversion zone with the speed of 434kg per hour, the raw material propylene carbonate enters the top of conversion zone with the speed of 137.5kg per hour, the mol ratio of the two is 7, and catalyzer sodium ethylate (be dissolved in earlier in the ethanol and form the solution that contains sodium ethylate 37.5%) enters the top of conversion zone with the speed of 2.75kg per hour.Provide reactive distillation processes required whole energy by the tower still by outer heat, the trim the top of column ratio is 0.8, and tower still temperature is 185～190 ℃, operates under normal pressure.The cat head gas mixture (refers to ethanol and diethyl carbonate gas mixture, down together), with the per hour speed discharge (not comprising quantity of reflux) of 470.1kg, without condensation, directly import in the extractive distillation column, the ratio of components of said gas mixture is: ethanol content is 66.2% (wt), and the content of diethyl carbonate is 33.8% (wt).Obtain content in the tower still and be 99.1% propylene glycol by product (all the other are propylene carbonate 0.12%, sodium ethylate be 0.86% and small amount of ethanol), behind the wherein contained sodium ethylate of further refining recovery, propylene glycol can be used as the commercially available prod.But recycle in the sodium ethylate retrieval system that reclaims.The transformation efficiency that with the propylene carbonate is benchmark is 99.9%.Extractive distillation column is operated under following operating mode:
Gas mixture enters the bottom of extraction section with the speed of 470.1kg per hour, extraction agent is a propylene carbonate, enter the top of extraction section with the speed of 1035kg per hour, alcoholic acid mol ratio in extraction agent and the gas mixture is 1.5, provide distillation operation needed whole energy by the tower still by outer heat, the trim the top of column ratio is 1.0, and tower still temperature is 160～180 ℃, operates under normal pressure.Getting purity in recovered overhead is 99.4% ethanol, discharges with the speed of 307.1kg per hour.The ethanol that reclaims can directly return in the reaction fractionating tower and recycle.The mixture that obtains propylene carbonate and diethyl carbonate in the tower still (is called for short two ester mixtures, down together), its ratio of components is: the propylene carbonate ester content is 86.4%, carbonic acid di-alcohol content is 13.5%, and a spot of ethanol, it is discharged with the speed of 1198kg per hour, and imports in the diester knockout tower.The diester knockout tower is operated under following operating mode:
Two ester mixtures enter the middle part of fractionation section with the speed of 1198kg per hour, by tower still D
1Provide fractionation process required whole energy by outer heat, tower still temperature is 160～180 ℃, and working pressure is 30～50KPa.Cat head per hour can obtain the diethyl carbonate 162.9kg product of purity greater than 99.8% (wt), the tower still per hour then reclaims and obtains the propylene carbonate 1035kg that purity is 99.95% (wt), and the propylene carbonate of recovery returns in the extractive distillation column and recycles.The loss of extraction agent is less than 0.005%.
Embodiment 4
In a process unit of mainly being formed by reaction fractionating tower, extractive distillation column and diester knockout tower, drop into material carbon vinyl acetate and ethanol, under the effect of catalyzer sodium ethylate, produce diethyl carbonate.
Said reaction fractionating tower is 1600 millimeters of diameters, high 20000 millimeters tray column, in establish 36 of column plates, wherein: conversion zone is 30, stripping section is 5, rectifying section is 1.
Said extractive distillation column is 1600 millimeters of diameters, high 15000 millimeters tray column, in establish 24 of column plates, wherein: extraction section is 15, stripping section is 7, rectifying section is 2.
Said diester knockout tower is 1000 millimeters of diameters, high 3000 millimeters tray column, in establish 3 of column plates, entirely in the fractionation section.Reaction fractionating tower is operated under following operating mode:
Feed ethanol enters conversion zone with the speed of 3110.2kg per hour bottom, material carbon vinyl acetate enters the top of conversion zone with the speed of 850kg per hour, the mol ratio of the two is 7, catalyzer sodium ethylate (its solution composition is with embodiment 3) enters the top of conversion zone with the speed of 20kg per hour, provide reactive distillation processes required whole energy by the tower still by outer heat, the trim the top of column ratio is 1.0, tower still temperature is 185～190 ℃, operates under normal pressure.Cat head gas mixture (the gas mixture that refers to ethanol and diethyl carbonate, down together) with the per hour speed discharge (not comprising quantity of reflux) of 3368.7kg, without condensation, directly import in the extractive distillation column, the ratio of components of gas mixture is: ethanol content is that 66.2% (wt), diethyl carbonate content are 33.8% (wt).Obtain content in the tower still and be 98.4% ethylene glycol by product (all the other are NSC 11801 0.25%, sodium ethylate 1.4% and a spot of ethanol), after further making with extra care the wherein contained sodium ethylate of recovery, ethylene glycol can be used as the commercially available prod, but recycles in the sodium ethylate retrieval system of recovery.The transformation efficiency that with the NSC 11801 is benchmark is 99.8%.Extractive distillation column is operated under following operating mode:
Gas mixture enters the bottom of extraction section with the speed of 3368.7kg per hour, extraction agent is a NSC 11801, enter the top of extraction section with the speed of 6400kg per hour, alcoholic acid mol ratio in extraction agent and the gas mixture is 1.5, provide distillation operation required whole energy by the tower still by outer heat, the trim the top of column ratio is 1.0, and tower still temperature is 160～180 ℃, operates under normal pressure.Obtaining purity in recovered overhead is 99.4% ethanol, discharges with the speed of 2735.7kg per hour.The ethanol that reclaims can directly return in the reaction fractionating tower and recycle.Obtain the mixture (being called for short two ester mixtures, down together) of NSC 11801 and diethyl carbonate in the tower still, its ratio of components is: the content of NSC 11801 is 91.0% (wt).Diethyl carbonate 8.97% and small amount of ethanol, it is discharged with the speed of 7033kg per hour, and imports in the diester knockout tower.The diester knockout tower is operated under following operating mode:
Two ester mixtures enter the middle part of fractionation section with the speed of 7033kg per hour, by tower still D
1Provide fractionation process required whole energy by outer heat, tower still temperature is 160～180 ℃, and full tower is operated under 30～50KPa.Per hour can obtain the diethyl carbonate 632.1kg product of purity at cat head greater than 99.8% (wt), the tower still is per hour recyclable to obtain the NSC 11801 6400kg that purity is 99.95 (wt), and the NSC 11801 of recovery is returned in the extractive distillation column and recycled.The wastage rate of extraction agent are less than 0.005%.
As seen from the above-described embodiment, can produce dialkyl carbonate according to method of the present invention, this will bring bright development prospect and huge economic benefit to the product portion that produces dialkyl carbonate undoubtedly efficient low-consume.
Claims (3)
1. the synthetic method of an improved dialkyl carbonate, it is a raw material with ethylene (propylene) carbonate and alcohol, produce dialkyl carbonate under the effect of catalyzer sodium alkoxide, be characterised in that: said synthetic method is mainly separated three technological processs by reactive distillation, extracting rectifying and diester and is formed, wherein:
(1) reactive distillation processes is to carry out in a tray column, and the operating mode during its operation is:
1. reactive distillation processes mainly carries out on the column plate of the conversion zone of tower
2. the two mol ratio of the alcohol of charging and ethylene (propylene) carbonate is 6～10
3. the trim the top of column ratio is 0.6～1.0
4. working pressure is 90～110Kpa
5. tower still temperature is 185～190 ℃;
(2) the extracting rectifying process is to carry out in a tray column, and the operating mode during its operation is:
Used extraction agent is the ethylene (propylene) carbonate identical with reaction mass when 1. extracting
2. extraction agent is 1～2 with the mol ratio of going into the alcohol in the tower material
3. the trim the top of column ratio is 0.6～1.2
4. working pressure is 70～101Kpa
5. tower still temperature is 160～180 ℃;
(3) the operation operating mode of diester knockout tower is:
1. the trim the top of column ratio is 0.4～0.6
2. working pressure is 30～50Kpa
3. tower still temperature is 160～180 ℃;
(4) said dialkyl carbonate is a class carbonic acid two lower alkyl esters.
2. the method for claim 1, it is characterized in that reactive distillation operation and extracting rectifying operate under the normal pressure carries out.
3. as the described method of one of claim 1～2, the trim the top of column ratio when it is characterized in that the extracting rectifying operation is 0.8～1.0.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94112211A CN1049212C (en) | 1994-06-24 | 1994-06-24 | Improved synthetic method of dialkyl carbonate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94112211A CN1049212C (en) | 1994-06-24 | 1994-06-24 | Improved synthetic method of dialkyl carbonate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1102826A CN1102826A (en) | 1995-05-24 |
| CN1049212C true CN1049212C (en) | 2000-02-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN94112211A Expired - Fee Related CN1049212C (en) | 1994-06-24 | 1994-06-24 | Improved synthetic method of dialkyl carbonate |
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| CN (1) | CN1049212C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005066110A1 (en) * | 2003-10-16 | 2005-07-21 | East China University Of Science And Technology | Combined production of dialkyl carbonate and diol |
| US10131620B2 (en) | 2015-10-20 | 2018-11-20 | Chang Chun Plastics Co., Ltd. | Process for producing dimethyl carbonate |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100364956C (en) * | 2004-08-09 | 2008-01-30 | 华东理工大学 | Method of distillation and ester exchange reaction for producing dimethyl carbonate and dihydroxyl alcohols |
| TWI378087B (en) | 2006-02-22 | 2012-12-01 | Shell Int Research | Process for the preparation of an alkanediol and a dialkyl carbonate |
| TW200740731A (en) | 2006-02-22 | 2007-11-01 | Shell Int Research | Process for the preparation of alkanediol |
| TWI382979B (en) | 2006-02-22 | 2013-01-21 | Shell Int Research | Process for the production of alkylene carbonate and use of alkylene carbonate thus produced in the manufacture of an alkane diol and a dialkyl carbonate |
| TWI383976B (en) | 2006-02-22 | 2013-02-01 | Shell Int Research | Process for the production of dialkyl carbonate and alkanediol |
| CN101381308B (en) * | 2008-10-22 | 2011-07-20 | 天津大学 | Preparation method of diethyl carbonate and methyl ethyl carbonate mixed ester |
| CN103641721B (en) * | 2013-12-18 | 2015-06-03 | 福州大学 | Energy-saving process for producing and separating dimethyl carbonate |
| CN107417534B (en) | 2017-06-20 | 2021-01-29 | 中国科学院过程工程研究所 | System and process for co-producing dimethyl carbonate and ethylene glycol |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4691041A (en) * | 1986-01-03 | 1987-09-01 | Texaco Inc. | Process for production of ethylene glycol and dimethyl carbonate |
| US5231212A (en) * | 1991-09-03 | 1993-07-27 | Bayer Aktiengesellschaft | Process for the continuous preparation of dialkyl carbonates |
-
1994
- 1994-06-24 CN CN94112211A patent/CN1049212C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4691041A (en) * | 1986-01-03 | 1987-09-01 | Texaco Inc. | Process for production of ethylene glycol and dimethyl carbonate |
| US5231212A (en) * | 1991-09-03 | 1993-07-27 | Bayer Aktiengesellschaft | Process for the continuous preparation of dialkyl carbonates |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005066110A1 (en) * | 2003-10-16 | 2005-07-21 | East China University Of Science And Technology | Combined production of dialkyl carbonate and diol |
| US10131620B2 (en) | 2015-10-20 | 2018-11-20 | Chang Chun Plastics Co., Ltd. | Process for producing dimethyl carbonate |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1102826A (en) | 1995-05-24 |
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