CN110437201B - Composite absorbent and method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate by using same - Google Patents
Composite absorbent and method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate by using same Download PDFInfo
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- CN110437201B CN110437201B CN201910785196.2A CN201910785196A CN110437201B CN 110437201 B CN110437201 B CN 110437201B CN 201910785196 A CN201910785196 A CN 201910785196A CN 110437201 B CN110437201 B CN 110437201B
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- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
- B01J31/0278—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre
- B01J31/0281—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member
- B01J31/0284—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member of an aromatic ring, e.g. pyridinium
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- C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
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- C07D303/04—Compounds containing oxirane rings containing only hydrogen and carbon atoms in addition to the ring oxygen atoms
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- 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 provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling to co-produce ethylene carbonate by using the composite absorbent. The composite absorbent comprises ionic liquid and ethylene carbonate, wherein the structure of the ionic liquid is shown as a formula I, a formula II or a formula III. The composite absorbent is used for absorbing ethylene oxide and carbon dioxide, the ionic liquid is also used as a catalyst in the absorption process, the ethylene oxide and the carbon dioxide are reacted to produce ethylene carbonate, pre-conversion is realized while absorption is carried out, the energy consumption is reduced, and the industrial application value is better. The invention also applies the composite absorbent to the ethylene oxide absorption and conversion coupling co-production of ethylene carbonate, directly couples the absorption and the conversion, realizes the one-step production of the ethylene carbonate, has simple operation and low equipment cost, reduces the steam stripping process, reduces the energy consumption, and realizes the requirements of economy, high efficiency, energy saving and environmental protection.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and particularly relates to a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate by using the composite absorbent.
Background
The ethylene carbonate called as green chemical raw material in 21 st century is a chemical intermediate and excellent solvent with wide application. Ethylene oxide, one of raw materials for synthesizing ethylene carbonate, is mainly oxidized to generate ethylene oxide under the action of a silver-containing catalyst, and impurity gases such as methane, ethane and the like exist in the process of preparing the ethylene oxide. In order to obtain purified ethylene oxide, the ethylene oxide is often absorbed from a mixed gas by an absorption method industrially, and then the ethylene oxide is purified to obtain high-purity ethylene oxide through processes of stripping, concentration and the like; and (3) catalytically synthesizing ethylene carbonate from the refined ethylene oxide and carbon dioxide in a reaction kettle.
In the process for producing ethylene carbonate, water is often used as an absorbent in industry, and the water is used as the absorbent, so that the selectivity is low, the latent heat of vaporization is large, and a large amount of energy consumption is caused, and therefore certain improvements are made in some domestic and foreign patents. US4221727a1 discloses a method using an organic solvent ethylene carbonate as an absorbent, US5559255A discloses a method using an organic solvent propylene carbonate as an absorbent, CN109422708A discloses a method using triethylene glycol dimethyl ether and ionic liquid as an absorbent, and the like. These absorbents improve the absorption capacity and selectivity of ethylene oxide, but the process of stripping ethylene oxide still consumes a large amount of energy in the whole process flow, and the process flow is complex, the equipment cost is high, and the one-time investment is large.
Therefore, in order to better realize the absorption of ethylene oxide in the mixed gas after the oxidation of ethylene and the production of ethylene carbonate, a novel absorbent and a novel process are still needed, so that the novel absorbent can not only efficiently absorb ethylene oxide, but also solve the problem of high energy consumption in the stripping process.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate by using the composite absorbent. The invention utilizes the composite absorbent of the ionic liquid and the ethylene carbonate ester to absorb the ethylene oxide and the carbon dioxide, the ionic liquid can also be used as a catalyst in the absorption process, and the ethylene oxide obtained by absorption is reacted with the carbon dioxide to produce the ethylene carbonate ester, thereby not only improving the absorption effect of the ethylene oxide, but also reducing the process of desorption and refining of the ethylene oxide, realizing pre-conversion during absorption, reducing energy consumption and having better industrial application value.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a composite absorbent, which includes an ionic liquid and ethylene carbonate, wherein the ionic liquid has a structure represented by formula I, formula ii, or formula iii:
wherein R in the formula I1And R2Each independently selected from any one of substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C2-C6 alkenyl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl or substituted or unsubstituted C1-C6 alkoxy;
r in formula II3、R4、R5And R6Each independently selected from any one of substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C2-C6 alkenyl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl or substituted or unsubstituted C1-C6 alkoxy;
r in formula III7、R8、R9And R10Each independently selected from any one of substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C2-C6 alkenyl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl or substituted or unsubstituted C1-C6 alkoxy;
the anion X in the formulae I, II and III-Each independently selected from Cl-、Br-Or I-Any one of them.
The term "C1-C6 alkyl" as used herein isRefers to a straight or branched chain alkyl group having 1, 2, 3, 4, 5 or 6 carbon atoms, including, without limitation, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, and the like. The term "C2-C6 alkenyl" refers to a straight or branched chain alkenyl group having 2, 3, 4, 5, or 6 carbon atoms, which includes at least one double bond in the molecular chain, including, without limitation, -CH ═ CH (CH)3)、-CH＝C(CH3)2、-C(CH3)＝CH2、-C(CH3)＝CH(CH3)、-C(CH2CH3)＝CH2Butadienyl, pentadienyl or hexadienyl groups, and the like. The term "C2-C6 alkynyl" refers to straight or branched chain alkynyl groups having 2, 3, 4, 5 or 6 carbon atoms, including, without limitation, -C.ident.CH, -C.ident.C (CH)3)、-C≡C(CH2CH3)、-CH2C≡CH、-CH2C≡C(CH3) or-CH2C≡C(CH2CH3) And the like. The term "C6-C30 aryl" is an aryl group having 6-30 carbon atoms, for example, and may contain 6, 12, or 18 carbon atoms and the like, including without limitation phenyl, naphthyl, or biphenyl, and the like. The term "C3-C30 heteroaryl" refers to a monocyclic, bicyclic, or tricyclic, etc. aromatic ring system having 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30, etc. ring atoms and which contains at least one heteroatom which may be the same or different, such as oxygen, nitrogen, or sulfur, and further may be benzo-fused in each instance, including, without limitation, thienyl, furyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, benzofuranyl, benzothienyl, benzoxazolyl, benzisoxazolyl, benzimidazolyl, benzotriazolyl, indazolyl, indolyl, isoindolyl, pyridyl, pyridazinyl, etc, Pyrimidinyl, pyrazinyl, triazinyl, quinolinyl, quinazolinyl, isoquinolinyl, and the like. The term "C1-C6 alkoxy" refers to a straight or branched chain alkoxy group having 1, 2, 3, 4, 5, or 6 carbon atoms including, without limitation, methoxy, ethoxyN-propoxy, isopropoxy or tert-butoxy, etc.
The invention utilizes the composite absorbent of the ionic liquid and the ethylene carbonate ester to absorb the ethylene oxide and the carbon dioxide, the ionic liquid can also be used as a catalyst in the absorption process, and the ethylene oxide obtained by absorption is reacted with the carbon dioxide to produce the ethylene carbonate ester, thereby not only improving the absorption effect of the ethylene oxide, but also reducing the process of desorption and refining of the ethylene oxide, realizing pre-conversion during absorption, reducing energy consumption and having better industrial application value.
The anion of the ionic liquid in the composite absorbent is selected from specific Cl-、Br-Or I-The cation of the ionic liquid can cause the polarization of the C-O bond of the ethylene oxide, and meanwhile, the halogen ion attacks the beta-carbon atom with smaller steric hindrance in an epoxy ring, so that the ethylene oxide is easy to open the ring and the carbon dioxide reacts to generate the ethylene carbonate.
Preferably, in formula I, formula ii and formula iii, the substituted groups are each independently selected from any one of hydroxyl, amino, nitro, aldehyde, ester, carboxyl, nitroso, amide or carbonyl.
Preferably, the mass ratio of the ionic liquid to the ethylene carbonate is 1 (1-10), and can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or the like.
The invention preferably controls the mass ratio of the ionic liquid and the ethylene carbonate within the above range, because when the content of the ionic liquid is too high, the viscosity of the composite absorbent is increased, the composite absorbent cannot be fully contacted with the ethylene oxide, and the absorption efficiency of the ethylene oxide can be reduced, while if the content of the ionic liquid is too low, the selective absorptivity of the composite absorbent is weakened, the absorption effect of the ethylene oxide can be influenced, and meanwhile, the content of the ionic liquid is too low, and the catalytic efficiency of the cycloaddition reaction of the ethylene oxide and the carbon dioxide can be obviously reduced in the absorption pre-reaction stage.
In a second aspect, the invention also provides a method for co-producing ethylene carbonate by coupling the absorption and conversion of ethylene oxide, wherein the method uses the composite absorbent as described in the first aspect.
The invention creatively adopts the ionic liquid and the ethylene carbonate compound as the absorbent to absorb, convert and couple the ethylene oxide, realizes the one-step absorption and conversion of the ethylene oxide and effectively reduces the energy consumption and the cost of the device.
Preferably, the method comprises the steps of: and (3) contacting the composite absorbent with feed gas containing ethylene oxide, and feeding the obtained ethylene oxide-rich absorption liquid into a main reactor to obtain ethylene carbonate.
The feed gas comprises the following components in percentage by mol: ethylene oxide 2.6%, methane 52.77%, ethylene 32.53%, oxygen 4.9%, carbon dioxide 1.5%, argon 4.18%, nitrogen 1% and ethane 0.52%. The raw material gas is a mixed gas obtained by oxidizing ethylene, ethylene oxide and carbon dioxide exist in the raw material gas at the same time, and in the absorption process, the ionic liquid can effectively absorb the ethylene oxide and the carbon dioxide and can catalyze the reaction of the ethylene oxide and the carbon dioxide to generate the ethylene carbonate, so that the pre-reaction for preparing the ethylene carbonate is realized while absorption is carried out, the energy consumption is reduced, the content of ethylene oxide tail gas in a rear-section carbonylation main reaction unit is reduced, the safety is ensured, and the industrial application value is better.
The pre-reaction of the present invention may have an ethylene oxide conversion of 2 to 35%, for example, 2%, 5%, 8%, 10%, 12%, 15%, 20%, 23%, 27%, 30%, 35%, or the like.
The conversion rate of the ethylene oxide in the pre-reaction stage is only 2-35% because the excess carbon dioxide cannot be provided in the pre-reaction stage and the catalyst cannot reach the optimal conversion rate at the pre-reaction temperature, so that the conversion rate of the ethylene oxide in the pre-reaction stage is low.
Preferably, the method comprises the steps of: and (2) the composite absorbent and feed gas containing ethylene oxide are in countercurrent full contact in an absorption tower, lean mixed gas after ethylene oxide removal at the tower top is treated and then returns to an ethylene oxidation stage, ethylene oxide-rich absorption liquid at the tower bottom enters a main reactor after heat exchange and reacts to obtain reaction liquid, one part of the obtained reaction liquid containing ionic liquid is used as absorption liquid for circulation, and the other part of the obtained reaction liquid is treated to obtain high-purity ethylene carbonate.
It should be noted that in the reaction stage, carbon dioxide is added to the main reactor, so that the amount of carbon dioxide is sufficient relative to ethylene oxide, i.e. sufficient carbon dioxide and ethylene oxide obtained by absorption react to form ethylene carbonate.
In the main reactor, ethylene oxide and carbon dioxide obtained by catalytic absorption of ionic liquid react to produce ethylene carbonate. For the tail gas treatment process after ethylene oxidation, at present, an absorption tower is adopted to absorb ethylene oxide, and the ethylene oxide enters a reactor to generate ethylene carbonate after steam stripping and refining. The invention creatively uses the composite absorbent of the ethylene carbonate and the ionic liquid for absorbing, converting and coupling the co-production of the ethylene carbonate for the first time, not only has higher absorption performance to the ethylene oxide, but also the ionic liquid has excellent performances of low steam pressure, small specific heat capacity and the like, and after complete reaction, the product can be used as the absorbent to be recycled in the absorption tower for recycling, thereby simplifying the separation cycle process. As for the process flow, the method directly couples absorption and conversion to realize one-step production of the ethylene carbonate, thereby not only having small workload and low equipment cost, but also reducing the steam stripping process, reducing the energy consumption and realizing the requirements of economy, high efficiency, energy conservation and environmental protection.
Preferably, the mass ratio (liquid-gas mass ratio) of the composite absorbent to the raw material gas containing ethylene oxide is (1-5):1, for example, 1:1, 1.5:1, 2:1, 2.3:1, 3:1, 3.5:1, 4:1 or 5:1, and preferably (2-3): 1.
Preferably, the operating pressure of the absorption column is 1 to 5MPa, and may be, for example, 1MPa, 1.5MPa, 2MPa, 2.3MPa, 3MPa, 3.5MPa, 4MPa, 4.6MPa or 5MPa, etc., preferably 1.5 to 2.5 MPa.
Preferably, the operating temperature of the absorption column is 50 to 100 ℃, for example, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃, etc., preferably 60 to 80 ℃.
Preferably, the reaction pressure of the main reactor is 1 to 5MPa, and may be, for example, 1MPa, 1.2MPa, 2MPa, 2.5MPa, 3MPa, 3.4MPa, 4MPa, 4.5MPa or 5MPa, etc., preferably 2 to 3 MPa.
Preferably, the reaction temperature of the main reactor is 80-300 ℃, for example, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃, 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃ or 300 ℃, preferably 100-.
Preferably, the reaction time is 0.5 to 5 hours, for example, 0.5 hour, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, etc., preferably 1 to 3 hours.
Preferably, the ethylene oxide-rich absorption liquid enters the main reactor after heat exchange to 100-200 ℃, and can be, for example, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃ or 200 ℃ and the like.
Preferably, a part of the reaction solution is cooled to 60 to 80 ℃ before entering the absorption tower, and may be, for example, 60 ℃, 62 ℃, 65 ℃, 68 ℃, 70 ℃, 73 ℃, 76 ℃ or 80 ℃.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention utilizes the composite absorbent of the ionic liquid and the ethylene carbonate ester to absorb the ethylene oxide and the carbon dioxide, the ionic liquid can also be used as a catalyst in the absorption process, and the ethylene oxide obtained by absorption is reacted with the carbon dioxide to produce the ethylene carbonate ester, thereby not only improving the absorption effect of the ethylene oxide, but also reducing the process of desorption and refining of the ethylene oxide, realizing pre-conversion during absorption, reducing energy consumption and having better industrial application value;
(2) the invention creatively uses the composite absorbent of the ethylene carbonate and the ionic liquid to absorb, convert and couple the ethylene carbonate for the first time, not only has higher absorption performance to the ethylene oxide, but also the ionic liquid has excellent performances of low steam pressure, small specific heat capacity and the like, and after complete reaction, the product can be used as the absorbent to be recycled in the absorption tower, thereby simplifying the separation cycle process. For the process flow, the method directly couples absorption and conversion to realize one-step production of the ethylene carbonate, so that the method has the advantages of small workload, low equipment cost, reduction of a stripping process, reduction of energy consumption and realization of the requirements of economy, high efficiency, energy conservation and environmental protection;
(3) in the process of co-producing ethylene carbonate by coupling the absorption and conversion of ethylene oxide, the absorption rate of ethylene oxide can reach more than 98.5% in the absorption stage, the conversion rate of ethylene oxide can reach 99.2% at most in the main reaction stage, and the selectivity is more than 92%.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
raw material gas containing 2.26 mol% of ethylene oxide at 80 ℃ enters an absorption tower from the bottom of the tower, composite absorbent ionic liquid 1- (2-hydroxyethyl) -3-methylimidazole bromine ([ Hemim ] Br) and ethylene carbonate are uniformly mixed according to the mass ratio of 1:10 and then enter the absorption tower from the top of the absorption tower (T1), the raw material gas is in countercurrent contact with the absorbent, the absorption temperature is 80 ℃, the operation pressure is 2MPa, the liquid-gas mass ratio is 3, the conversion rate of absorbing the ethylene oxide at the pre-conversion section is 28.8%, the concentration of the ethylene oxide at the top of the absorption tower is 69ppm, and the absorption rate is 99.9%.
And adding the absorption liquid into a reactor, raising the reaction temperature to 125 ℃, reacting for 1h under the pressure of 2MPa, and detecting to obtain the product with the conversion rate of the residual ethylene oxide of 95.2% and the selectivity of 99.8%.
Example 2
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
raw material gas containing 2.26 mol% of ethylene oxide at 80 ℃ enters an absorption tower from the bottom of the tower, composite absorbent ionic liquid 1-hexyl-3-methylimidazole bromine ([ Hmim ] Br) and ethylene carbonate are uniformly mixed according to the mass ratio of 1:10 and then enter the absorption tower (T1) from the top of the tower, the raw material gas and the absorbent are in countercurrent contact, the absorption temperature is 80 ℃, the operation pressure is 2MPa, the liquid-gas mass ratio is 3, the conversion rate of the ethylene oxide at the absorption pre-conversion section is 15.8%, the concentration of the ethylene oxide at the top of the absorption tower is 227ppm, and the absorption rate is 99.5%.
And adding the absorption liquid into a reactor, raising the reaction temperature to 120 ℃, reacting for 3 hours under the pressure of 2MPa, and detecting to obtain the product with the conversion rate of the residual ethylene oxide of 52.5 percent and the selectivity of 99.8 percent.
Example 3
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
raw material gas containing 2.26 mol% of ethylene oxide at 80 ℃ enters an absorption tower from the bottom of the tower, composite absorbent ionic liquid 1- (2-hydroxyethyl) -3-methylimidazole bromine ([ Hemim ] Br) and ethylene carbonate are uniformly mixed according to the mass ratio of 1:9 and then enter the absorption tower from the top of the absorption tower (T1), the raw material gas is in countercurrent contact with the absorbent, the absorption temperature is 80 ℃, the operation pressure is 2MPa, the liquid-gas mass ratio is 3, the conversion rate of absorbing the ethylene oxide at the pre-conversion section is 32.2%, the concentration of the ethylene oxide at the top of the absorption tower is 44ppm, and the absorption rate is 99.9%.
And adding the absorption liquid into a reactor, raising the reaction temperature to 120 ℃, reacting for 1h under the pressure of 2MPa, and detecting to obtain the product with the conversion rate of the residual ethylene oxide of 99.2 percent and the selectivity of 99.8 percent.
Example 4
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
the method comprises the following steps of enabling feed gas containing 2.26 mol% of ethylene oxide at 80 ℃ to enter an absorption tower from the bottom of the tower, enabling the feed gas and an absorbent to enter the absorption tower from the top of the absorption tower (T1) after uniformly mixing composite absorbent ionic liquid 2-hydroxyethyl tributylammonium bromide (HETBAB) and ethylene carbonate according to the mass ratio of 1:10, enabling the feed gas to be in countercurrent contact with the absorbent, enabling the absorption temperature to be 80 ℃, the operation pressure to be 2MPa, the liquid-gas mass ratio to be 3, enabling the conversion rate of the ethylene oxide at an absorption pre-conversion section to be 29.2%, enabling the concentration of the ethylene oxide at the top of the absorption tower to be 55ppm, and enabling.
And adding the absorption liquid into a reactor, raising the reaction temperature to 125 ℃, reacting for 1h under the pressure of 2MPa, and detecting to obtain the product with the conversion rate of the residual ethylene oxide of 95.8 percent and the selectivity of 99.8 percent.
Example 5
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
the raw material gas containing 2.26 mol% of ethylene oxide at 80 ℃ enters an absorption tower from the bottom of the tower, the composite absorbent ionic liquid ethylene bis (triphenyl phosphonium bromide) (E TPB) and ethylene carbonate are uniformly mixed according to the mass ratio of 1:10 and then enter the absorption tower (T1) from the top of the tower, the raw material gas and the absorbent are in countercurrent contact, the absorption temperature is 80 ℃, the operation pressure is 3MPa, the liquid-gas mass ratio is 3, the conversion rate of the ethylene oxide at the absorption pre-conversion section is 25.6%, the concentration of the ethylene oxide at the top of the absorption tower is 95ppm, and the absorption rate is 99.8%.
And adding the absorption liquid into a reactor, raising the reaction temperature to 160 ℃, reacting for 3 hours under the pressure of 3MPa, and detecting to obtain the product with the conversion rate of the residual ethylene oxide of 92.9 percent and the selectivity of 99 percent.
Example 6
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
the method comprises the following steps of enabling feed gas containing 2.26 mol% of ethylene oxide at 60 ℃ to enter an absorption tower from the bottom of the tower, enabling composite absorbent ionic liquid 1- (2-hydroxyethyl) -3-methylimidazole bromine ([ Hemim ] Br) and ethylene carbonate to uniformly mix in a mass ratio of 1:1, enabling the feed gas to enter the absorption tower from the top of a T1, enabling the feed gas to be in countercurrent contact with an absorbent, enabling the absorption temperature to be 60 ℃, the operation pressure to be 2MPa, and enabling the liquid-gas mass ratio to be 2, wherein the conversion rate of absorbing ethylene oxide at a pre-conversion section to be 18.2%, the concentration of ethylene oxide at the top of the absorption tower 2 to be 152ppm, and enabling the absorption rate to be 99..
And adding the absorption liquid into a reactor, raising the reaction temperature to 80 ℃, reacting for 0.5h under the pressure of 5MPa, and detecting to obtain the product with the conversion rate of the residual ethylene oxide of 65.5 percent and the selectivity of 98.2 percent.
Example 7
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
the method comprises the following steps of enabling a feed gas containing 2.26 mol% of ethylene oxide at 100 ℃ to enter an absorption tower from the bottom of the tower, enabling a composite absorbent ionic liquid 1- (2-hydroxyethyl) -3-methylimidazole bromine ([ Hemim ] Br) and ethylene carbonate to uniformly mix in a mass ratio of 1:5, enabling the mixture to enter the absorption tower from the top of a T1, enabling the feed gas to be in countercurrent contact with an absorbent, enabling the absorption temperature to be 100 ℃, the operation pressure to be 2MPa, enabling the liquid-gas mass ratio to be 3, enabling the conversion rate of the ethylene oxide at an absorption pre-conversion section to be 30.1%, enabling the concentration of the ethylene oxide at the top of the absorption tower to be 395ppm, and enabling the absorption rate to.
And adding the absorption liquid into a reactor, raising the reaction temperature to 300 ℃, reacting for 5 hours under the pressure of 2MPa, and detecting to obtain the product with the conversion rate of the residual ethylene oxide of 95.2 percent and the selectivity of 98.2 percent.
Example 8
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
the method comprises the following steps of enabling feed gas containing 2.26 mol% of ethylene oxide at 60 ℃ to enter an absorption tower from the bottom of the tower, enabling the feed gas and an absorbent to enter the absorption tower from the top of the absorption tower (T1) after uniformly mixing composite absorbent ionic liquid 2-hydroxyethyl tributylammonium bromide (HETBAB) and ethylene carbonate according to the mass ratio of 1:7, enabling the feed gas to be in countercurrent contact with the absorbent, enabling the absorption temperature to be 60 ℃, the operation pressure to be 2MPa, enabling the liquid-gas mass ratio to be 2, enabling the conversion rate of the ethylene oxide at an absorption pre-conversion section to be 17.2%, enabling the concentration of the ethylene oxide at the top of the absorption tower to be 108ppm, and enabling the.
And adding the absorption liquid into a reactor, raising the reaction temperature to 200 ℃, reacting for 2 hours under the pressure of 1.5MPa, and detecting to obtain the product with the conversion rate of the residual ethylene oxide of 85.1 percent and the selectivity of 92 percent.
Example 9
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which are different from the embodiment 1 only in that: the mass ratio of 1- (2-hydroxyethyl) -3-methylimidazolium bromide ([ Hemim ] Br) to ethylene carbonate is 1: 12.
The conversion rate of the ethylene oxide at the absorption pre-conversion section is 17%, the concentration of the ethylene oxide at the top of the absorption tower is 158ppm, and the absorption rate is 99.4%; the absorption liquid is added into a reactor, and after reaction, the conversion rate of the residual ethylene oxide is 95.2 percent and the selectivity is 99.8 percent.
Comparative example 1
The embodiment provides a composite absorbent and a method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate, which comprises the following specific operation steps:
raw material gas containing 2.26 mol% of ethylene oxide at 80 ℃ enters an absorption tower from the bottom of the tower, absorbent ethylene carbonate enters the absorption tower from the top of the absorption tower (T1), the raw material gas and the absorbent are in countercurrent contact, the absorption temperature is 80 ℃, the operation pressure is 2MPa, the liquid-gas mass ratio is 3, the concentration of the ethylene oxide at the top of the absorption tower is 450ppm, and the absorption rate is 98.2%.
Adding the absorption liquid into a main reactor, adding a catalyst 1-butyl-3-methylimidazolium bromide ([ bmim ] Br), raising the reaction temperature to 120 ℃, reacting for 3 hours under the pressure of 2MPa, and detecting to obtain the catalyst, wherein the conversion rate of the residual ethylene oxide is 51.6%, and the selectivity is 99.9%.
The embodiment and the detection result show that in the process of co-producing ethylene carbonate by absorbing, converting and coupling ethylene oxide, the absorption rate of ethylene oxide can reach more than 98.5% in the absorption stage, which shows that the composite absorbent adopting the ionic liquid and the ethylene carbonate has higher absorption capacity to the ethylene oxide, and the ionic liquid has excellent performances of low vapor pressure, small specific heat capacity and the like, and the product after complete reaction can be recycled to the absorption tower as the absorbent for recycling, thereby simplifying the separation cycle process. In the absorption stage, the conversion rate of the ethylene oxide is 15.8-32.2%, in the main reaction stage, the conversion rate of the ethylene oxide can reach 99.2% at most, and the selectivity is over 99%. For the whole process flow, the invention directly couples the absorption and the conversion of the ethylene oxide to realize the one-step production of the ethylene carbonate, thereby not only reducing the workload and the equipment cost, but also reducing the steam stripping process, reducing the energy consumption and realizing the requirements of economy, high efficiency, energy conservation and environmental protection.
In comparison with example 1, comparative example 1 employed only ethylene carbonate in the absorption stage of ethylene oxide and then carried out the esterification reaction of ethylene oxide and carbon dioxide by adding a catalyst in the main reaction stage, and it can be seen from the data that the absorption rate of ethylene oxide in comparative example 1 was lower than the absorption efficiency of ethylene oxide using the composite absorbent containing an ionic liquid in the absorption stage and the conversion rate of ethylene oxide in the main reaction stage was also lower than the conversion rate of the ionic liquid-catalyzed main reaction in example 1. This shows that the addition of the ionic liquid in the process of absorbing and converting ethylene oxide not only enhances the selective absorption of ethylene oxide, but also has higher catalytic efficiency for the esterification reaction of ethylene oxide and carbon dioxide.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (16)
1. A method for co-producing ethylene carbonate by coupling ethylene oxide absorption and conversion is characterized by comprising the following steps: the method comprises the following steps of (1) enabling a composite absorbent to be in countercurrent full contact with feed gas containing ethylene oxide in an absorption tower, processing lean mixed gas after ethylene oxide is removed from the tower top and then returning the processed lean mixed gas to an ethylene oxidation stage, enabling ethylene oxide-rich absorption liquid in a tower kettle to enter a main reactor after heat exchange and react to obtain reaction liquid, and enabling one part of the obtained reaction liquid containing ionic liquid to be used as absorption liquid to circulate and the other part of the obtained reaction liquid to be processed to obtain high-purity ethylene carbonate;
the composite absorbent consists of ionic liquid and ethylene carbonate, wherein the structure of the ionic liquid is shown as a formula I, a formula II or a formula III:
wherein R in the formula I1And R2Each independently selected from substituted or unsubstituted C1-C6 alkyl;
r in formula II3、R4、R5And R6Each independently selected from substituted or unsubstituted C1-C6 alkyl;
r in formula III7、R8、R9And R10Each independently selected from any one of substituted or unsubstituted C1-C6 alkyl and substituted or unsubstituted phenyl;
the anion X in the formulae I, II and III-Each independently selected from Cl-、Br-Or I-Any one of the above;
the R is1-R10Each of the substituted groups in (1) is independently selected from hydroxyl.
2. The method according to claim 1, wherein the mass ratio of the ionic liquid to the ethylene carbonate is 1 (1-10).
3. The method according to claim 1, wherein the mass ratio of the composite absorbent to the feed gas containing ethylene oxide is (1-5): 1.
4. The method of claim 3, wherein the mass ratio of the composite absorbent to the ethylene oxide-containing feed gas is (2-3): 1.
5. The process according to claim 1, wherein the operating pressure of the absorption column is 1 to 5 MPa.
6. The process according to claim 5, wherein the operating pressure of the absorption column is 1.5 to 2.5 MPa.
7. The process according to claim 1, wherein the operating temperature of the absorption column is 50 to 100 ℃.
8. The process according to claim 7, wherein the operating temperature of the absorption column is 60 to 80 ℃.
9. The process according to claim 1, wherein the reaction pressure of the main reactor is 1 to 5 MPa.
10. The process according to claim 9, characterized in that the reaction pressure of the main reactor is 2-3 MPa.
11. The method according to claim 1, wherein the reaction temperature of the main reactor is 80-300 ℃.
12. The method as claimed in claim 11, wherein the reaction temperature of the main reactor is 100-200 ℃.
13. The process according to claim 1, characterized in that the reaction time of the main reactor is between 0.5 and 5 h.
14. The process according to claim 13, characterized in that the reaction time of the main reactor is 1-3 h.
15. The method as claimed in claim 1, wherein the ethylene oxide-rich absorption liquid enters the main reactor after heat exchange at 100-200 ℃.
16. The method according to claim 1, wherein a part of the reaction solution is cooled to 60-80 ℃ before entering the absorption tower.
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| CN201910785196.2A CN110437201B (en) | 2019-08-23 | 2019-08-23 | Composite absorbent and method for ethylene oxide absorption, conversion and coupling co-production of ethylene carbonate by using same |
| PCT/CN2020/080560 WO2021036238A1 (en) | 2019-08-23 | 2020-03-23 | Composite absorbent and use thereof |
| US17/637,241 US20220274944A1 (en) | 2019-08-23 | 2020-03-23 | Composite absorbent and use thereof |
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| US4221727A (en) * | 1979-08-17 | 1980-09-09 | The Dow Chemical Company | Ethylene oxide recovery |
| CN105732566A (en) * | 2014-12-12 | 2016-07-06 | 中国石油天然气股份有限公司 | Method of producing ethylene carbonate |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4221727A (en) * | 1979-08-17 | 1980-09-09 | The Dow Chemical Company | Ethylene oxide recovery |
| CN105732566A (en) * | 2014-12-12 | 2016-07-06 | 中国石油天然气股份有限公司 | Method of producing ethylene carbonate |
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| Title |
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| 以碳酸乙烯酯为吸收剂吸收环氧乙烷的方法;陈玮娜;《化工技术与开发》;20131015;第42卷(第10期);第31-33页 * |
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