CN113387811A - Energy-saving consumption-reducing method for producing dimethyl carbonate by ester exchange method - Google Patents
Energy-saving consumption-reducing method for producing dimethyl carbonate by ester exchange method Download PDFInfo
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- CN113387811A CN113387811A CN202110880286.7A CN202110880286A CN113387811A CN 113387811 A CN113387811 A CN 113387811A CN 202110880286 A CN202110880286 A CN 202110880286A CN 113387811 A CN113387811 A CN 113387811A
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- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 26
- 150000002148 esters Chemical group 0.000 title claims abstract description 13
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 13
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 138
- 238000006243 chemical reaction Methods 0.000 claims abstract description 60
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims abstract description 19
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims abstract description 18
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 claims abstract description 14
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 claims abstract description 10
- 230000008569 process Effects 0.000 claims abstract description 9
- 239000003054 catalyst Substances 0.000 claims description 23
- 239000000463 material Substances 0.000 claims description 20
- 238000001704 evaporation Methods 0.000 claims description 18
- 230000008020 evaporation Effects 0.000 claims description 17
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 14
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 14
- 239000012071 phase Substances 0.000 claims description 13
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 12
- 239000007791 liquid phase Substances 0.000 claims description 12
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 claims description 8
- 238000005809 transesterification reaction Methods 0.000 claims description 8
- 239000001569 carbon dioxide Substances 0.000 claims description 7
- 238000000066 reactive distillation Methods 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 4
- 238000010992 reflux Methods 0.000 claims description 4
- 230000001105 regulatory effect Effects 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 3
- 238000009833 condensation Methods 0.000 claims description 2
- 230000005494 condensation Effects 0.000 claims description 2
- 239000002815 homogeneous catalyst Substances 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 7
- 230000002194 synthesizing effect Effects 0.000 abstract description 6
- 238000002309 gasification Methods 0.000 abstract description 4
- 230000008901 benefit Effects 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 9
- 238000005265 energy consumption Methods 0.000 description 5
- 239000002608 ionic liquid Substances 0.000 description 5
- 238000003786 synthesis reaction Methods 0.000 description 5
- -1 DMC compound Chemical class 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 238000007670 refining Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000002131 composite material Substances 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 239000002574 poison Substances 0.000 description 2
- 231100000614 poison Toxicity 0.000 description 2
- 229960004063 propylene glycol Drugs 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- YGYAWVDWMABLBF-UHFFFAOYSA-N Phosgene Chemical compound ClC(Cl)=O YGYAWVDWMABLBF-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- VAYGXNSJCAHWJZ-UHFFFAOYSA-N dimethyl sulfate Chemical compound COS(=O)(=O)OC VAYGXNSJCAHWJZ-UHFFFAOYSA-N 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 239000003254 gasoline additive Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 125000000956 methoxy group Chemical group [H]C([H])([H])O* 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000012022 methylating agents Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
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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
-
- 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
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
The invention relates to an energy-saving and consumption-reducing method for producing dimethyl carbonate by ester exchange method, which is used for preparing propylene oxide (or ethylene oxide) and CO2The exothermic heat generated in the process of synthesizing propylene carbonate (or ethylene carbonate) through reaction is removed by methanol gasification through a kettle-type evaporator, and the gasified methanol enters an ester exchange reaction rectifying tower, so that the heat load of the reaction rectifying tower is reduced, and the energy-saving effect is achieved. The invention has the advantages of simple flow, low investment, optimized production process of dimethyl carbonate by ester exchange method, and reduced steam consumption by more than 10% compared with the production device with the same scale.
Description
Technical Field
The invention belongs to the field of fine chemical production, and particularly relates to an energy-saving and consumption-reducing method for producing dimethyl carbonate by using a transesterification method.
Background
Dimethyl carbonate (DMC) is a very useful organic compound listed as a non-toxic chemical in Europe in 1992. The DMC compound contains carbonyl, methyl, methoxy and carbonylmethoxy in the molecule, so that the DMC compound can be used as an intermediate for organic synthesis, can replace dimethyl sulfate (hypertonic poison) to be used as a methylating agent and phosgene (hypertonic poison) to be used as a carbonylating agent, can also be used as a gasoline additive to improve the octane number and oxygen content of gasoline, and can also be used as a coating solvent, and DMC has excellent solubility property and lower viscosity on lithium salt, so that the DMC compound can be used as an electrolyte of a lithium battery, and is widely applied to the aspects of electric automobiles and 5G base stations, thereby having high industrial application value.
In the DMC production process, the ester exchange method is also the main production method and has already been industrially applied. The method firstly adopts CO2And Propylene Oxide (PO) or ethylene oxideAlkyl (EO) is used for synthesizing Propylene Carbonate (PC) or Ethylene Carbonate (EC), and then the PC or EC is subjected to transesterification reaction with methanol to obtain DMC and 1, 2-Propylene Glycol (PG) or Ethylene Glycol (EG). However, the steam consumption in the process of producing DMC by ester exchange method is very high, about 8.5 tons of steam are consumed for producing every 1 ton of DMC in the prior art, and how to reduce the energy consumption of ester exchange process is the key for improving the economic benefit of the device.
CN103641721B discloses an energy-saving process for producing and separating dimethyl carbonate, wherein distillate at the top of a pressure rectifying tower of DMC and methanol azeotrope is directly returned to the lower part of a reaction rectifying tower to be used as supplement of methanol. As is known, a pressure rectifying tower is used for separating DMC and methanol azeotrope, pure methanol can not be obtained at the tower top, but new DMC and methanol azeotrope under new pressure is obtained, according to the difference of the tower top pressure (0.8-1.5 MPa), the DMC content in the new azeotrope is 13% -8% (wt), after methanol containing much DMC returns to the reaction rectifying tower, the equilibrium of the transesterification reaction between PC or EC and methanol is influenced, and the conversion rate of PC or EC is reduced; meanwhile, DMC brought into the reaction rectifying tower and methanol are azeotroped again, energy is consumed, and the energy-saving effect is not achieved.
Surprisingly, CN108440298A and CN206886993U disclose the same energy-saving and consumption-reducing device for a dimethyl carbonate device, the contents in the device are almost the same (different applicant), new methanol/DMC azeotrope vapor at the top of the DMC/methanol azeotrope pressurized rectifying tower is introduced into a reboiler at the bottom of the reactive rectifying tower to be used as a heat source, and meanwhile, the methanol/DMC azeotrope vapor at the top of the normal pressure methanol rectifying tower is pressurized and heated by a heat pump to be used as the heat source of the reboiler at the bottom of the tower, so as to reduce the energy consumption. In fact, in the current industrial production of DMC, the new methanol/DMC azeotrope vapor at the top of the pressurized rectifying tower is respectively introduced into the reboiler at the tower bottom of the reactive rectifying tower and the reboiler at the tower bottom of the normal pressure methanol rectifying tower as heat sources, and under the condition that energy-saving measures are taken, the energy consumption of the ester exchange method DMC is reduced to 8.5 tons of steam/ton of DMC.
CN 106608865A discloses an energy-saving method for ethylene carbonate synthesis, which realizes that the reaction of ethylene oxide and carbon dioxide is an exothermic reaction, and each three-stage synthesis reactor is provided with a steam generator for supplying heat source of other heating devices of a whole plant or generating electricity, so as to reduce the energy consumption of the whole plant. Because the temperature of the existing synthesis reactor is not high, generally 140-160 ℃, the steam pressure of the byproduct is not high, generally 0.1-0.3MPa, the low-pressure steam belongs to low-pressure steam, and the low-pressure steam is not used on a DMC self device and is also low in power generation efficiency. Therefore, energy savings are not a significant contribution to the DMC installation.
Thus, there is no known method for reacting propylene oxide or ethylene oxide with CO in the prior art2The heat of reaction of (a) is used as a heat source for the dimethyl carbonate plant.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide an energy-saving and consumption-reducing method for producing dimethyl carbonate by using a transesterification method.
PO and CO2The reaction for synthesizing PC can be represented by formula (1), EO and CO2The reaction for synthesizing EC can be represented by formula (2):
thus, propylene oxide or ethylene oxide with CO2The reaction for synthesizing propylene carbonate or ethylene carbonate is exothermic and belongs to a strong exothermic reaction, especially the reaction of ethylene oxide and CO2The exothermic amount of reaction (2) is larger. The heat release of the reaction is not removed in time, so that the temperature of the reactor can be raised, and safety accidents are caused, and therefore, the heat removal is needed. The common practice in the prior production is (1) to cool the reaction materials by a circulating water cooler, and (2) to generate low-pressure steam by vaporization of water through a steam generator to take away heat. However, due to the improvement of the catalyst, the ionic liquid catalyst is adopted, so that the reaction temperature is reduced to 130-160 ℃ from the original 180-200 ℃, and the reaction is carried out at room temperatureThe temperature of the generated steam is usually 140-150 ℃, the temperature of the generated steam is usually 120-130 ℃, the generated steam belongs to low-pressure steam, and the low-pressure steam is basically not used in a dimethyl carbonate device, so that the energy-saving effect cannot be achieved.
The inventor recognizes that in the process of synthesizing dimethyl carbonate by transesterification, the molar ratio of propylene carbonate (or ethylene carbonate) to methanol is usually 10: 1-15: 1, methanol is in large excess, the excess methanol is used for forming an azeotrope with a product DMC and moving away from the top of a reactive distillation tower, the equilibrium of the transesterification is broken, and the conversion rate of PC (or EC) is improved, the excess methanol is gasified in the reactive distillation tower, and the gasification energy is provided by steam in a reboiler at the bottom of the tower. If the excessive methanol enters the reactive distillation tower in a gas phase mode, the steam usage amount in the reboiler of the tower kettle is reduced, thereby achieving the purpose of energy conservation.
The invention operates as follows:
PO (or EO) and CO2The feed was continuously fed to the lower part of the tubular reactor (1) by a feed pump, and the makeup catalyst 1 and the recovered circulating catalyst 1 were also fed from the lower part of the tubular reactor (1). Random packing is filled in the tubular reactor (1) to improve the uniformity of the stream mixing. Because the reaction releases heat, the temperature of the materials in the reactor rises gradually in the upward flow, and because the reaction is a reversible exothermic reaction, in order to improve the equilibrium conversion rate, the materials need to be cooled, so the materials discharged from the top of the reactor enter a cooling evaporator (2), the reaction materials move along the tube pass, the methanol is evaporated and gasified to remove the reaction heat, and the gasified methanol enters the lower part of a reaction rectifying tower (8). The material after heat removal and temperature reduction through the cooling evaporator (2) is mostly circulated back to the tubular reactor (1) through the pump (12), and a small part enters the heat insulation tubular reactor (3), after heat insulation reaction, the conversion rate of PO (or EO) is further improved, and then the material enters the flash tank (5) after the pressure is controlled through the pressure regulating valve (4), and a small amount of unreacted PO (or EO) and excessive CO2Evaporating gas phase from liquid, passing through a demister, entering a condenser (6), condensing condensable gas, and refluxing to a flash tank (5),the non-condensable gas is discharged from the condenser (6) and enters the subsequent flow treatment. The liquid material in the flash tank (5) enters an evaporation separator (7), the evaporation separator (7) is operated under negative pressure, products PC (or EC) and the like are extracted from the upper part in a gas phase and enter a subsequent rectifying tower to be refined to obtain PC (or EC products), and the catalyst 1 is discharged from the bottom of the evaporation separator (7) and returns to the lower part of the tubular reactor (1) through a pump (13).
The invention has the following patent effects: an energy-saving and consumption-reducing system for producing dimethyl carbonate by an ester exchange method fully utilizes the characteristics that methanol is excessive in ester exchange reaction and needs to be gasified in a reaction rectifying tower (8), and uses the gasification of the methanol to transfer heat for heat release of a tubular reactor (1), thereby achieving the purpose of transferring heat of the reactor, achieving the purpose of gasifying the methanol without using steam, and realizing the effect of heat coupling. Therefore, the steam consumption of the reboiler of the reactive distillation column (8) is greatly reduced, the purposes of energy conservation and consumption reduction are achieved, and the steam consumption can be reduced by more than 10 percent compared with a production device with the same scale.
The present invention will be described in detail below with reference to the accompanying drawings.
FIG. 1 is a flow chart of the present invention.
Drawings
The symbols in fig. 1 are illustrated as follows:
the method comprises the following steps of 1-tubular reactor, 2-evaporative cooler, 3-adiabatic tubular reactor, 4-pressure regulating valve, 5-flash tank, 6, 9-condenser, 7-evaporative separator, 8-reactive distillation column, 10-reflux tank, 11-reboiler, and 12, 13, 14 and 15-pump.
As can be seen from fig. 1, the present invention employs the following steps:
(1) the supplemented and recovered catalyst 1, carbon dioxide and propylene oxide (or ethylene oxide) are continuously introduced into the lower part of the tubular reactor (1) for reaction;
(2) the reaction materials in the tubular reactor (1) flow out from the upper part and enter the evaporative cooler (2), and the reaction materials pass through the tube pass;
(3) the liquid phase methanol enters the shell pass of the evaporative cooler (2), and the gas phase methanol is extracted from the upper part of the evaporative cooler (2) and enters the lower part of the ester exchange reaction rectifying tower (8).
The reaction material cooled by the cooling evaporator (2) is connected with a pump (12), one part of the outlet of the pump (12) enters the tubular reactor (1), and the other part enters the heat-insulating tubular reactor (3) from the bottom;
the top outlet pipeline of the heat-insulating tubular reactor (3) is connected with the pressure regulating valve (4), and the materials enter the upper part of the flash tank (5) after pressure regulation and control;
a demister is arranged at the upper part of the flash tank (5), evaporated light components leave from a top gas phase port and enter a condenser (6), and after condensation, non-condensable gas enters a subsequent device for treatment; the liquid phase material enters the upper part of the evaporation separator (7) from a bottom outlet;
an inlet of the evaporation separator (7) is connected with a bottom liquid phase outlet of the flash tank (5) through a pipeline, and the recovered catalyst 1 is connected with an inlet of a pump (13) through a bottom outlet of the evaporation separator (7) and returns to a catalyst 1 feeding hole at the bottom of the tubular reactor (1);
a rectifying section is arranged at the upper part of the reaction rectifying tower (8), liquid phase raw materials comprise propylene carbonate or ethylene carbonate, methanol and a catalyst 2 and enter from the lower part of the rectifying section, a gas phase outlet is arranged at the top part of the reaction rectifying tower (8) and is connected with a condenser (9), condensate enters a reflux tank (10), one part of the condensate flows back through a pump (15), and the other part of the condensate enters the subsequent methanol/dimethyl carbonate azeotrope separation process; a reboiler (11) is arranged at the lower part of the reactive distillation column (8) to provide heat; the product propylene glycol or ethylene glycol, unreacted methanol and the catalyst 2 are connected with a pump (14) through a bottom outlet pipeline and enter a subsequent separation process.
The reaction temperature of the tubular reactor (1) is 130-160 ℃.
The operation pressure of the tubular reactor (1) is 2.0-6.0 MPa.
The flow rate of the liquid phase methanol in the evaporative cooler (2) is controlled by the temperature of the reaction materials flowing out of the evaporative cooler (2).
The catalyst 1 is a homogeneous catalyst.
Detailed Description
It can be seen from the above disclosed technical solutions that the exothermic heat of PC or EC synthesis can be used for methanol gasification in the rectification column of transesterification reaction according to the process of the present invention, which undoubtedly brings significant energy saving and huge economic benefits for the production of 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
The specification of the straight tube reactor (1) is phi 450 multiplied by 20000mm, the specification of the adiabatic reactor (3) is phi 400 multiplied by 20000, and the two reactors adopt the operation mode of bottom feeding and top discharging. Filling propylene carbonate containing 50kg of composite ionic liquid catalyst in a straight-tube reactor (1), heating and boosting, then starting to feed raw materials of propylene oxide and carbon dioxide, wherein the feed amount of the propylene oxide is 500kg/h, the feed amount of the carbon dioxide is 417kg/h, discharging from the top of the straight-tube reactor (1), feeding into a tube pass of an evaporative cooler (2), pumping 740kg/h of liquid-phase methanol into a shell pass, gasifying the methanol, feeding into the lower part of a reaction rectifying tower (8), controlling the reaction temperature of the straight-tube reactor (1) at 135-140 ℃, and controlling the reaction pressure at 4.5 MPa; the reaction materials enter a flash tank (5) after passing through an adiabatic reactor (3), the pressure of the flash tank (5) is controlled to be 0.1-0.2 MPa, and excessive CO is separated and removed2And unreacted trace propylene oxide; the liquid in the flash tank (5) enters an evaporation separator (7) from the bottom, the temperature of the evaporation separator (5) is controlled at 130-150 ℃, the pressure is controlled at 5-6kPa, and the gas-phase propylene carbonate is evaporated from the upper part of the evaporation separator (7) and enters a subsequent propylene carbonate refining tower for refining; the ionic liquid catalyst returns to the catalyst inlet of the straight-tube reactor (1) from the bottom of the evaporation separator (7).
After the gas-phase methanol of the evaporative cooler (2) enters the reaction rectifying tower (8), the heat load of the reboiler (11) is reduced, the steam can be saved by 0.5t/tDMC, and the energy-saving effect is obvious.
Example 2
The specification of the straight tube reactor (1) is 400X 18000mm, the specification of the adiabatic reactor (3) is 350X 18000mm, and the two reactors adopt the operation mode of bottom entry and top exit. Filling 38kg of ethylene carbonate containing a composite ionic liquid catalyst in a straight-tube reactor (1), heating and boosting, then starting to feed ethylene oxide and carbon dioxide, wherein the feed amount of ethylene oxide is 400kg/h, the feed amount of carbon dioxide is 440kg/h, discharging from the top of the straight-tube reactor (1), feeding into the tube pass of an evaporative cooler (2), pumping 1960kg/h of liquid-phase methanol in the shell pass, feeding into the lower part of a reaction rectifying tower (8) after the methanol is gasified, controlling the reaction temperature of the straight-tube reactor (1) at 125-135 ℃, and controlling the reaction pressure at 4.3 MPa; the reaction materials enter a flash tank (5) after passing through an adiabatic reactor (3), the pressure of the flash tank (5) is controlled to be 0.1-0.2 MPa, and excessive CO is separated and removed2And unreacted trace ethylene oxide; the liquid in the flash tank (5) enters an evaporation separator (7) from the bottom, the temperature of the evaporation separator (5) is controlled at 130-150 ℃, the pressure is controlled at 5-6kPa, and the gas-phase ethylene carbonate is evaporated from the upper part of the evaporation separator (7) and enters a subsequent ethylene carbonate refining tower for refining; the ionic liquid catalyst returns to the catalyst inlet of the straight-tube reactor (1) from the bottom of the evaporation separator (7).
After the gas-phase methanol of the evaporative cooler (2) enters the reaction rectifying tower (8), the heat load of the reboiler (11) is reduced, 1.25t/tDMC of steam can be saved, and the energy-saving effect is obvious.
Claims (6)
1. An energy-saving and consumption-reducing method for producing dimethyl carbonate by using a transesterification method is characterized by comprising the following steps:
(1) the supplemented and recovered catalyst 1, carbon dioxide and propylene oxide (or ethylene oxide) are continuously introduced into the lower part of the tubular reactor (1) for reaction;
(2) the reaction materials in the tubular reactor (1) flow out from the upper part and enter the evaporative cooler (2), and the reaction materials pass through the tube pass;
(3) the liquid phase methanol enters the shell pass of the evaporative cooler (2), and the gas phase methanol is extracted from the upper part of the evaporative cooler (2) and enters the lower part of the ester exchange reaction rectifying tower (8).
2. The method of claim 1, wherein:
the reaction material cooled by the cooling evaporator (2) is connected with a pump (12), one part of the outlet of the pump (12) enters the tubular reactor (1), and the other part enters the heat-insulating tubular reactor (3) from the bottom;
the top outlet pipeline of the heat-insulating tubular reactor (3) is connected with the pressure regulating valve (4), and the materials enter the upper part of the flash tank (5) after pressure regulation and control;
a demister is arranged at the upper part of the flash tank (5), evaporated light components leave from a top gas phase port and enter a condenser (6), and after condensation, non-condensable gas enters a subsequent device for treatment; the liquid phase material enters the upper part of the evaporation separator (7) from a bottom outlet;
an inlet of the evaporation separator (7) is connected with a bottom liquid phase outlet of the flash tank (5) through a pipeline, and the recovered catalyst 1 is connected with an inlet of a pump (13) through a bottom outlet of the evaporation separator (7) and returns to a catalyst 1 feeding hole at the bottom of the tubular reactor (1);
a rectifying section is arranged at the upper part of the reaction rectifying tower (8), liquid phase raw materials comprise propylene carbonate or ethylene carbonate, methanol and a catalyst 2 and enter from the lower part of the rectifying section, a gas phase outlet is arranged at the top part of the reaction rectifying tower (8) and is connected with a condenser (9), condensate enters a reflux tank (10), one part of the condensate flows back through a pump (15), and the other part of the condensate enters the subsequent methanol/dimethyl carbonate azeotrope separation process; a reboiler (11) is arranged at the lower part of the reactive distillation column (8) to provide heat; the product propylene glycol or ethylene glycol, unreacted methanol and the catalyst 2 are connected with a pump (14) through a bottom outlet pipeline and enter a subsequent separation process.
3. The process according to claim 1, wherein the reaction temperature of the tubular reactor (1) is 130 to 160 ℃.
4. The process according to claim 1, wherein the tubular reactor (1) is operated at a pressure of 2.0 to 6.0 MPa.
5. The method as claimed in claim 1, characterized in that the flow rate of the liquid phase methanol in the evaporative cooler (2) is controlled by the temperature of the reaction mass flowing out of the evaporative cooler (2).
6. The process of claim 1 wherein the catalyst 1 is a homogeneous catalyst.
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| CN113731320A (en) * | 2021-09-30 | 2021-12-03 | 沈阳工业大学 | Dimethyl carbonate production device and method based on resource utilization |
| CN113731320B (en) * | 2021-09-30 | 2023-11-21 | 沈阳工业大学 | Dimethyl carbonate production device and method based on resource utilization |
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