CN111943927A - Method for preparing propylene (or ethylene) carbonate by continuous reaction injection - Google Patents
Method for preparing propylene (or ethylene) carbonate by continuous reaction injection Download PDFInfo
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- CN111943927A CN111943927A CN202010890048.XA CN202010890048A CN111943927A CN 111943927 A CN111943927 A CN 111943927A CN 202010890048 A CN202010890048 A CN 202010890048A CN 111943927 A CN111943927 A CN 111943927A
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- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D317/00—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D317/08—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3
- C07D317/10—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings
- C07D317/32—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D317/34—Oxygen atoms
- C07D317/36—Alkylene carbonates; Substituted alkylene carbonates
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D317/00—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D317/08—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3
- C07D317/10—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings
- C07D317/32—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D317/34—Oxygen atoms
- C07D317/36—Alkylene carbonates; Substituted alkylene carbonates
- C07D317/38—Ethylene carbonate
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Abstract
The invention relates to a method for preparing propylene (or ethylene) carbonate by continuous reaction injection, which mainly comprises the following steps: urea and propylene (or ethylene) glycol are used as raw materials, and propylene (or ethylene) carbonate is continuously and efficiently prepared by a plurality of reaction injection kettles which are connected in series in the presence of a catalyst. The method has the advantages of high urea conversion rate (up to more than 99.8 percent), high propylene carbonate (or ethylene carbonate yield (up to more than 95 percent), low energy consumption, simple process and the like, can continuously and efficiently prepare the propylene carbonate (or ethylene carbonate), and undoubtedly brings good development prospect and huge economic benefit to the industries of propylene carbonate (or ethylene carbonate) and dimethyl carbonate. The method for producing the propylene carbonate (or ethylene carbonate) has the advantages of simple process flow, mild reaction conditions, environmental friendliness, low production cost and the like, and is a novel method for easily realizing industrial production.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and particularly relates to a method for preparing propylene carbonate or ethylene carbonate by continuously reacting and spraying urea and propylene glycol or ethylene glycol.
Background
Propylene carbonate and ethylene carbonate are organic solvents with excellent performance, high boiling point and high polarity, are also important organic chemicals, and are widely applied to the fields of organic synthesis, gas separation, battery dielectric, metal extraction and the like.
The traditional industrial method for synthesizing the propylene carbonate mainly takes propylene oxide and carbon dioxide as raw materials, and the propylene carbonate is obtained by pressure reaction under the action of a catalyst, and a large part of the produced propylene carbonate is used for synthesizing dimethyl carbonate. With the wide application of the green chemical product dimethyl carbonate, more and more dimethyl carbonate production devices are used, and in the process of dimethyl carbonate by the ester exchange method, 0.8 ton of propylene glycol is needed as a byproduct when 1 ton of dimethyl carbonate is produced, and a large amount of propylene glycol as the byproduct seriously exceeds the market demand. Propylene glycol cannot be sold, and the economy of a dimethyl carbonate device is directly influenced. If the propylene glycol can be converted into propylene carbonate, the propylene carbonate and methanol are subjected to transesterification reaction to synthesize dimethyl carbonate and propylene glycol, and the propylene glycol is recycled, the problem of the outlet of the propylene glycol in the process of synthesizing the dimethyl carbonate by ester exchange is solved.
It has been found that propylene carbonate can be obtained by reacting cheap urea with propylene glycol, for example, CN1421431A discloses that propylene carbonate can be synthesized by catalyzing the reaction of propylene glycol and urea with solid base as catalyst under vacuum or nitrogen. CN1298696C discloses a method for synthesizing ethylene carbonate (or propylene carbonate) by reacting urea with ethylene glycol or propylene glycol under the action of a composite metal oxide under the condition of 0-0.5 MPa or introducing nitrogen. EP0443758a1 proposes a process for synthesizing olefin carbonate from urea and aliphatic diol at normal pressure (or elevated pressure) using a homogeneous catalyst containing tin, but the conversion of urea is less than 66%, the product selectivity to urea is only 63%, and most of the urea is decomposed during the reaction. EP0581131A2 is an improvement, and proposes that under the reduced pressure, metal powder or compound of zinc, magnesium, lead and calcium is used as a catalyst to synthesize the carbonic olefin ester, so that the yield of the carbonic olefin ester is remarkably improved, and the yield of the carbonic olefin ester calculated by urea is 80-92%. For another example, CN101979142A discloses the preparation of propylene carbonate by using mixed metal carbonate as catalyst and reacting under the condition of introducing nitrogen gas under normal pressure. Because the metal carbonate is easily decomposed to form oxides under the high-temperature reaction condition, the catalyst is unstable, and the performance of the catalyst is influenced.
However, the reaction of urea and propylene (or ethylene) glycol to synthesize propylene (or ethylene) carbonate is a reversible equilibrium reaction, and in order to increase the conversion rate of urea, the method of removing the generated ammonia from the reaction zone by evacuation or nitrogen gas introduction is generally adopted in the literature, namely, the method of reaction separation is known, for example, CN2873777Y discloses that the propylene carbonate is produced by using a vacuum stirring reactor, and the method is difficult to adapt to continuous production. CN204474557U discloses that propylene carbonate is synthesized by combining a reaction kettle and a desorption tower, the reaction in the reaction kettle reaches the balance, ammonia is removed by vacuum desorption in the desorption tower, and the reaction balance is broken, so that the urea conversion rate is improved; because the reaction speed of the urea and the propylene glycol is not fast, the conversion rate of the urea in the material delivered from the desorption tower kettle is not high, and the problem of low utilization rate of raw materials exists due to more urea. CN103420972A discloses a method for synthesizing propylene carbonate (or ethylene carbonate) by combining a plurality of reactive distillation columns, and although the method has high urea conversion rate, the method also has the problems of high investment due to the use of column internals such as packing materials and the like, and the problem of blockage of the column internals due to the existence of catalyst solids in the materials.
Therefore, no method for efficiently, stably and continuously producing propylene (or ethylene) carbonate by using urea and propylene (or ethylene) glycol has been known in the prior art.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for simply, efficiently and continuously preparing propylene carbonate (or ethylene carbonate) by using urea and propylene glycol as raw materials.
The technical scheme for realizing the purpose of the invention is as follows:
when urea reacts with propylene (or ethylene) glycol under the action of a catalyst metal oxide, propylene (or ethylene) carbonate can be generated, taking the reaction of urea with propylene glycol as an example (the reaction of urea with ethylene glycol is similar), the reaction equation is shown as (1):
because the reaction is a reversible reaction, when the propylene carbonate is continuously produced on a large scale, the conversion rate of the urea cannot be improved because the materials in the reactor are more and the ammonia has certain solubility in the propylene carbonate and the propylene glycol, and the ammonia is difficult to rapidly and thoroughly remove simply by stirring and vacuum.
The inventor finds that in order to improve the selectivity of the propylene (or ethylene) carbonate, ammonia is required to be separated from a reaction zone as soon as possible, and the conversion rate of urea and the selectivity of the propylene (or ethylene) carbonate are improved by increasing the gas-liquid mass transfer area so that the generated ammonia leaves a reaction material as soon as possible. Through spraying reaction material in reation kettle, form the liquid material fine droplet, greatly increased gas-liquid mass transfer area, reduced the mass transfer resistance for the ammonia of dissolving in liquid can volatilize fast, and the ammonia concentration in this kind of liquid phase reduces, and the reaction just can go on toward the direction that generates propylene carbonate (or ethylene). The combination of a plurality of reaction jet reactors can lead the conversion rate of urea to reach more than 99.8 percent, and the device has simple and high-efficiency structure.
The invention relates to a method for continuously and efficiently preparing propylene (or ethylene) carbonate, which comprises the following steps:
(1) the reactor is formed by connecting 1-5 reaction kettles in series;
(2) continuously introducing a catalyst, urea and propylene (or ethylene) glycol into a reaction kettle;
(3) one part of liquid output by the discharge pump at the bottom of each reaction kettle is fed into a subsequent reactor, and the other part of liquid is circularly returned to a gas phase space in the reaction kettle;
(4) the liquid which is circularly returned is sprayed into liquid drops below the reaction kettle through a nozzle in the kettle;
(5) and a product from the last reaction kettle is output by a kettle bottom discharge pump, one part of the product is circularly returned to the gas phase space of the reaction kettle, and the other part of the product is sent to a subsequent flow for product separation after a catalyst is separated by a subsequent filter.
Wherein the molar ratio of propylene glycol (or ethylene) to urea is 1: 1-5: 1, the operating pressure of the reaction kettle is 30-70 kPa, the reaction temperature is 140-180 ℃, and the hourly circulation amount of the materials circularly returned to the reaction kettle is 0.5-10 times of the volume of the liquid in the kettle.
The residence time of the materials in the reaction kettle is 0.5-5 h.
By adopting the technical scheme, the conversion rate of urea can reach more than 99.8 percent, and the yield of propylene carbonate (or ethylene carbonate) can reach more than 95 percent.
Drawings
FIG. 1 is a schematic flow chart of a method for synthesizing propylene carbonate (or ethylene carbonate) by reacting urea and propylene glycol (or ethylene glycol).
Some symbols in FIG. 1 are illustrated as follows:
1,6, 11-reaction spray kettle, 2,7, 12-nozzle, 3,8, 13-reflux condenser, 4,9, 14-vacuum regulating valve, 5,10, 15-discharge pump.
Detailed Description
Referring to fig. 1, the present invention is realized by:
continuously adding a solution of reactants of urea and propylene (or ethylene) glycol and a metal oxide catalyst into a reaction injection kettle (1), wherein the molar ratio of the propylene (or ethylene) glycol to the urea is 1: 1-5: 1, and the catalyst accounts for 0.1-5% of the total weight of the reactants. The heating temperature of the material is controlled at 140-180 ℃, and the pressure is controlled at 30-70 kPa. The reactants and the catalyst are partially pumped into a reaction injection kettle (6) by a pump (5), most of materials are injected into liquid drops through a nozzle (2), the liquid drops are circularly returned to the kettle (1), and the circulating amount is 0.5-8 times of the material volume of the kettle (1). The ammonia generated by the reaction, the partially vaporized propylene (or ethylene) glycol and a small amount of propylene (or ethylene) carbonate are discharged from the upper part and enter a condenser (3), after being condensed by the condenser (3), the liquid flows back to the kettle (1) along a return pipe, and the ammonia gas which can not be condensed enters a vacuum pipeline and enters a subsequent ammonia recovery device through a vacuum pump. In the reaction injection tank (6), the operating conditions were similar to those of the tank (1). The reactants and the catalyst are partially pumped into a reaction injection kettle (11) by a pump (10), most of materials are injected into liquid drops through a nozzle (7) and circularly returned to the kettle (6), and the circulating amount is 0.5-10 times of the volume of the materials in the kettle (6). The ammonia generated by the reaction, the partially vaporized propylene (or ethylene) glycol and a small amount of propylene (or ethylene) carbonate are discharged from the upper part and enter a condenser (8), after being condensed by the condenser (8), the liquid flows back to the kettle (6) along a return pipe, and the ammonia gas which can not be condensed enters a vacuum pipeline and enters a subsequent ammonia recovery device through a vacuum pump. In the reaction injection tank (11), the operating conditions were similar to those of the tank (1). In the reaction injection tank (11), the operating conditions were similar to those of the tank (1). The reactants and the catalyst are partially pumped into a subsequent reaction injection kettle by a pump (15) or directly enter a subsequent catalyst separation device, most of the materials are injected into liquid drops through a nozzle (12) and circularly return to the kettle (11), and the circulating amount is 0.5-10 times of the material volume of the kettle (11). The ammonia generated by the reaction, the partially vaporized propylene (or ethylene) glycol and a small amount of propylene (or ethylene) carbonate are discharged from the upper part and enter a condenser (13), after being condensed by the condenser (13), the liquid flows back to the kettle (11) along a return pipe, and the ammonia gas which can not be condensed enters a vacuum pipeline and enters a subsequent ammonia recovery device through a vacuum pump.
The technical scheme disclosed by the invention shows that the method can simply, efficiently and continuously prepare the propylene (or ethylene) carbonate, which undoubtedly brings good development prospect and huge economic benefit to the industry of the dimethyl carbonate.
The present invention is further illustrated by the following examples, which are not intended to limit the scope of the present invention.
Example 1
In a two-step method dimethyl carbonate production device of urea of 4 ten thousand tons/year, three reaction spraying kettles are connected in series to carry out alcoholysis reaction of urea and propylene glycol. The volume of the reaction kettle is 25m33705kg/h of urea, 8447kg/h of propylene glycol and 60.7kg/h of metal oxide catalyst were continuously added to the first reaction vessel. The reaction temperature of each reaction jet was 165 ℃ and the operating pressure was 45 kPa. The volume of the material in the first reaction injection kettle is kept to be 12.5m3The residence time in the first reaction jet was about 1 h. Part of the material in the first reaction injection kettle enters the second reaction injection kettle through a pump, and the flow of the material circulating back to the first reaction kettle is 25m3H is used as the reference value. The number of the nozzles in the reaction jet kettle is 10, and the nozzles are arranged in two layers. Ammonia and partially vaporized propylene glycol produced by the reaction and a small amount of carbonThe acrylic ester is discharged from the upper part and enters a condenser, after being condensed by the condenser, the liquid flows back to the reaction injection kettle along a return pipe, and the ammonia gas which can not be condensed enters a vacuum pipeline and enters a subsequent ammonia recovery device through a vacuum pump. The circulating amount and the nozzle of the second and third reaction jet kettles are the same as those of the first reaction jet kettle.
And a part of materials in the third reaction injection kettle enter a subsequent catalyst filter through a pump, and the catalyst is separated and can be recycled. The material after catalyst separation is a mixture of propylene glycol and propylene carbonate, and can be separated by a conventional rectification method. The analysis calculation shows that the conversion rate of urea is 99.9 percent and the yield of propylene carbonate is 95.8 percent.
Example 2
In a 10 ten thousand ton/year urea two-step method dimethyl carbonate production device, the alcoholysis reaction of urea and propylene glycol is carried out by adopting a mode of connecting four reaction injection kettles in series. The volume of the reaction kettle is 45m3Urea at 9530kg/h, propylene glycol at 169900 kg/h and metal oxide catalyst at 132kg/h were continuously added to the first reactor. The reaction temperature of each reaction jet was 165 ℃ and the operating pressure was 45 kPa. The volume of the material in the first reaction injection kettle is kept to be 27m3The residence time in the first reaction jet was about 1 h. Part of the material in the first reaction injection kettle enters the second reaction injection kettle through a pump, and the flow of the material circulating back to the first reaction kettle is 60m3H is used as the reference value. The number of the nozzles in the reaction injection kettle is 30, and the nozzles are arranged in two layers. And discharging ammonia generated by the reaction, partially vaporized propylene glycol and a small amount of propylene carbonate from the upper part, feeding the ammonia, the partially vaporized propylene glycol and the small amount of propylene carbonate into a condenser, condensing the ammonia by the condenser, feeding liquid back to the reaction injection kettle along a return pipe, feeding ammonia which cannot be condensed into a vacuum pipeline, and feeding the ammonia into a subsequent ammonia recovery device through a vacuum pump. The circulating amount and the nozzle of the second, third and fourth reaction jet kettles are the same as those of the first reaction jet kettle.
And a part of materials in the fourth reaction injection kettle enter a subsequent catalyst filter through a pump, and the catalyst is separated and can be recycled. The material after catalyst separation is a mixture of propylene glycol and propylene carbonate, and can be separated by a conventional rectification method. The analysis calculation shows that the conversion rate of urea is 100 percent and the yield of propylene carbonate is 97.5 percent.
Claims (10)
1. A method for preparing propylene (or ethylene) carbonate by continuous reaction injection mainly comprises the following steps: the preparation method is characterized in that the propylene carbonate (or ethylene carbonate) is prepared by taking urea and propylene glycol (or ethylene glycol) as raw materials under the action of a catalyst metal oxide, and is characterized in that:
(1) the reactor is formed by connecting 1-5 reaction kettles in series;
(2) continuously introducing a catalyst, urea and propylene (or ethylene) glycol into a reaction kettle;
(3) one part of liquid output by the discharge pump at the bottom of each reaction kettle is fed into a subsequent reactor, and the other part of liquid is circularly returned to a gas phase space in the reaction kettle;
(4) the liquid which is circularly returned is sprayed into liquid drops below the reaction kettle through a nozzle in the kettle;
(5) and a product from the last reaction kettle is output by a kettle bottom discharge pump, one part of the product is circularly returned to the gas phase space of the reaction kettle, and the other part of the product is sent to a subsequent flow for product separation after a catalyst is separated by a subsequent filter.
2. The method of claim 1, wherein the reaction sparging process is performed in each reaction vessel.
3. The method of claim 1, wherein the urea, propylene (or ethylene) glycol and catalyst are continuously fed from a first reactor, or wherein a portion of the urea, propylene (or ethylene) glycol and catalyst are continuously fed from a first reactor and another portion are continuously fed from a second reactor.
4. The method of claim 1 or 2, wherein the material in each reaction kettle is heated by a jacket (or reboiler), forced circulated by a discharge pump of the reaction kettle, one part enters the next reaction kettle, the other part returns to the reaction kettle from the upper part and is sprayed into liquid drops through a nozzle arranged in the kettle, and the ammonia gas generated in the kettle and the saturated vapor of the propylene (or ethylene) glycol and the propylene (or ethylene) carbonate partially vaporized enter the condenser from the upper part of the reaction kettle.
5. The method of claims 1, 4, wherein: the nozzles are composed of 1-100 nozzles, and can be arranged on the same layer plane or different layer planes.
6. The method of claim 1, wherein: the liquid condensed from the condenser above the reaction kettle flows back to the reaction kettle.
7. The method of claim 1, wherein the reaction vessel is operated at a pressure of 30 to 70kPa and a reaction temperature of 140 to 180 ℃.
8. The process of claim 1, wherein the molar ratio of propylene (or ethylene) glycol to urea feed is from 1:1 to 5: 1.
9. The method of claim 1, wherein the amount of material circulated back to the reactor is 0.5 to 10 times the volume of liquid in the reactor per hour.
10. The method of claim 1, wherein the residence time of the material in the reaction kettle is 0.5 to 5 hours.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103420972A (en) * | 2013-08-01 | 2013-12-04 | 华东理工大学 | Method for continuously preparing propylene carbonate or ethylene carbonate |
| CN104059047A (en) * | 2014-07-10 | 2014-09-24 | 中国科学院山西煤炭化学研究所 | Continuous reaction technology for urea-synthesized cyclic carbonate, raw material mixer and kettle type reactor |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103420972A (en) * | 2013-08-01 | 2013-12-04 | 华东理工大学 | Method for continuously preparing propylene carbonate or ethylene carbonate |
| CN104059047A (en) * | 2014-07-10 | 2014-09-24 | 中国科学院山西煤炭化学研究所 | Continuous reaction technology for urea-synthesized cyclic carbonate, raw material mixer and kettle type reactor |
Non-Patent Citations (1)
| Title |
|---|
| 李韶璞: ""喷射回路反应器中文丘里喷射器混合特性的研究"", 《中国优秀硕士学位论文全文数据库 工程科技I辑》 * |
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