CN112679318A - Device and method for purifying and recovering circulating solvent in propylene oxide production process - Google Patents
Device and method for purifying and recovering circulating solvent in propylene oxide production process Download PDFInfo
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- 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
Abstract
The invention provides a device and a method for purifying and recovering a circulating solvent in the production process of propylene oxide, wherein the purifying and recovering device comprises a hydrogenation unit, a rectification unit, a cooling unit and an ion exchange unit, wherein the bottom outlet of the hydrogenation unit is connected with the inlet of the rectification unit, and the top outlet of the rectification unit is sequentially connected with the cooling unit and the ion exchange unit. According to the device, various impurity components generated in the production process of propylene oxide are removed through the arrangement of units such as hydrogenation, rectification, ion exchange and the like, the total content of impurities is reduced to below 10ppm, and the purification and recovery of a circulating solvent are realized; by purifying and recycling the circulating solvent, the influence of the existence of impurities on the service life of the catalyst is avoided, the regeneration period of the catalyst is long, and the selectivity of propylene oxide generated by the reaction is high; the device has the advantages of simple structure, simple and convenient operation of the method, lower device and operation cost, suitability for removing various impurities and high economic benefit.
Description
Technical Field
The invention belongs to the technical field of product separation and recovery, and relates to a device and a method for purifying and recovering a circulating solvent in the production process of propylene oxide.
Background
Propylene Oxide (PO) is an important organic chemical raw material, is mainly used for producing polyether, propylene glycol, isopropanolamine and the like, is also a main raw material of a surfactant, a demulsifier and a pesticide emulsifier, and derivatives of the PO are widely applied to industries such as automobiles, buildings, food, tobacco, cosmetics and the like and are important raw materials of fine chemical products.
The traditional method for industrially producing the propylene oxide mainly comprises a chlorohydrination method and an oxidation method, wherein the chlorohydrination method has mature production process and low requirement on the purity of the raw material propylene, but a large amount of waste water and waste residues are generated in the production process, and cannot meet the requirement of a green process along with the increasing severe environmental situation; the co-oxidation method has high requirement on the purity of propylene, large process operation pressure, high equipment cost, more co-products and low yield of propylene oxide, so the method is also severely restricted. In recent years, the direct oxidation of hydrogen peroxide (HPPO) to produce propylene oxide has attracted more and more attention, the method only generates propylene oxide and water in the production process, the process flow is simple, the product yield is high, no pollution is caused, the value of byproducts is high, the method belongs to an environment-friendly green production process, and the method is a main production process adopted by a newly-built propylene oxide project for a period of time in the future.
The process for producing propylene oxide by the HPPO method is usually carried out in a circulating solvent, after propylene and product propylene oxide are recovered from reaction products, the circulating solvent is further separated from water, and then the circulating solvent is returned to a reaction unit. CN 111574478A discloses a process for preparing propylene oxide by oxidizing propylene with hydrogen peroxide, comprising the following steps: hydrogen peroxide, methanol and propylene are fully mixed and react in a fixed bed reactor; pumping the product into a deoxygenation tower for gas stripping and deoxygenation, and feeding tail gas into a tail gas absorption tower; the deoxidized product is sent into a propylene recovery tower, unreacted propylene is extracted, and the propylene is recycled to the reactor after propane removal; carrying out crude separation of propylene oxide on the product after removing propylene; extracting and rectifying the crude epoxypropane to obtain a high-purity epoxypropane product; the solvent after the epoxypropane is separated enters a solvent recovery tower, and the recovered solvent is recycled back to the reactor through a tail gas absorption tower; in the reaction process, the solvent is separated from water and then circulated back to the reactor, but in the reaction, impurities such as aldehydes, ketones, esters, peroxides, polymers and the like are generated besides propylene oxide, the impurities are difficult to remove from the solvent in a common rectification mode, and if the impurities are circulated back to a reaction unit, the service life and the selectivity of the propylene epoxidation catalyst are greatly influenced, so that the long-period operation and the economical efficiency of the device are further influenced.
CN 110105173A discloses a high-efficiency purification method for HPPO process recovered solvent, which comprises the steps of reacting the recovered solvent of the HPPO process with hydrogen in the presence of a hydrogenation catalyst in a fixed bed reactor, wherein the hydrogenation catalyst comprises copper oxide and zinc oxide as active ingredients, zirconium oxide for improving the thermal stability of the catalyst, and a promoter carbon nano tube, impurities in the recovered solvent are only subjected to hydrogenation catalysis, are converted into other substances, are not separated, and the removal degree of the impurities is limited, so that the service life of the catalyst is still influenced.
In summary, for recycling the recycled solvent in the propylene oxide production process, appropriate equipment and process combinations need to be selected according to the impurity types, so that the impurity content in the solvent is sufficiently reduced, the selectivity of the catalyst is improved, and the service life of the catalyst is prolonged.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a device and a method for purifying and recovering a circulating solvent in the production process of propylene oxide.
In order to achieve the purpose, the invention adopts the following technical scheme:
on one hand, the invention provides a purification and recovery device for a circulating solvent in the production process of propylene oxide, which comprises a hydrogenation unit, a rectification unit, a cooling unit and an ion exchange unit, wherein the bottom outlet of the hydrogenation unit is connected with the inlet of the rectification unit, and the top outlet of the rectification unit is sequentially connected with the cooling unit and the ion exchange unit.
According to the invention, the HPPO method is adopted to produce the propylene oxide, the propylene and the product propylene oxide are respectively separated from each other to obtain a reaction product, the residual components are mainly circulating solvents, and impurities such as aldehydes, ketones, peroxides and polymers can be generated in the reaction process and exist in the circulating solvents, so that the circulating solvents can be reused in a reaction system after purification and purification.
The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.
As a preferable technical scheme of the invention, the hydrogenation unit comprises a hydrotreater, and the hydrotreater is provided with a circulating solvent inlet and a hydrogen inlet.
Preferably, the hydrotreater comprises any one of a fixed bed reactor, a slurry bed reactor, an ebullating bed reactor or a suspended bed reactor, or a combination of at least two of these, typical but non-limiting examples being: a combination of a fixed bed reactor and a slurry bed reactor, a combination of a slurry bed reactor and a fluidized bed reactor, a combination of a fixed bed reactor, a fluidized bed reactor and a suspended bed reactor, and the like.
In the invention, the hydrotreater can be arranged in multiple stages according to requirements, so that different types of reactors can be selected to be combined, arranged in series or in parallel, and also can be selected simultaneously to fully achieve the aim of converting or removing impurities.
As a preferable technical scheme of the invention, the rectifying unit sequentially comprises a first rectifying tower and a second rectifying tower, and the bottom outlet of the first rectifying tower is connected with the inlet of the second rectifying tower.
Preferably, the first rectification column and the second rectification column are independently a plate column or a packed column.
In the invention, because the components in the circulating solvent are various and the single rectification separation condition is difficult to fully achieve the separation effect, the two-stage rectification tower is arranged, different rectification conditions can be selected for separation, and the separation of the circulating solvent and water is realized.
Preferably, the number of theoretical plates of the first rectification column is 20 to 50, for example, 20, 25, 30, 35, 40, 45 or 50, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the number of theoretical plates of the second rectifying column is 30 to 50, such as 30, 33, 36, 40, 43, 45, 48 or 50, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferable technical scheme of the invention, the cooling unit comprises a cooler, and top outlets of the first rectifying tower and the second rectifying tower are connected with an inlet of the cooler.
Preferably, the cooling unit comprises a first cooler and a second cooler, the top outlet of the first rectifying tower is connected with the inlet of the first cooler, the top outlet of the second rectifying tower is connected with the inlet of the second cooler, and the outlets of the first cooler and the second cooler are both connected with the inlet of the ion exchange unit.
In the invention, the cooling unit is arranged to cool the top material flow separated by the rectifying tower, so that the temperature of the top material flow is suitable for ion exchange, and the problems of low impurity removal rate and even damage to ion exchange resin caused by overhigh temperature are avoided.
As a preferred solution of the invention, the ion exchange unit comprises at least 2 ion exchangers, for example 2, 3 or 4, the number of which is chosen in relation to the flow rate and the impurity content of the stream to be treated, the resin loading of the ion exchangers, etc.
Preferably, the ion exchangers are arranged in series and/or in parallel.
Preferably, the ion exchanger is packed with an ion exchange resin.
In another aspect, the present invention provides a method for purifying and recovering a circulating solvent by using the above apparatus, the method comprising the steps of:
(1) carrying out hydrogenation treatment on the circulating solvent to be treated to obtain a hydrogenation material;
(2) rectifying the hydrogenation material obtained in the step (1), and separating to obtain a rectified circulating solvent and a rectified water solution;
(3) and (3) cooling the rectified circulating solvent obtained in the step (2) and then carrying out ion exchange treatment to obtain the purified circulating solvent.
As a preferable technical scheme of the invention, the to-be-treated circulating solvent in the step (1) is a circulating solvent obtained after a propylene raw material and a propylene oxide product are separated from a reaction product of a propylene oxide production process.
Preferably, the composition of the recycled solvent of step (1) comprises mainly methanol.
In the invention, the circulating solvent comprises various impurities, such as aldehydes, ketones, esters, peroxides and polymers, besides the main component methanol, and the impurities need to be removed respectively through different treatment operations.
Preferably, the temperature of the hydrotreating in step (1) is 50 to 110 ℃, for example 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ or 110 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the pressure of the hydrotreating in step (1) is 0.1 to 1.0MPa, for example, 0.1MPa, 0.2MPa, 0.3MPa, 0.5MPa, 0.6MPa, 0.8MPa, or 1.0MPa, but is not limited to the values listed above, and other values not listed above within the range of values are also applicable.
In the present invention, unless otherwise specified, all pressures referred to are relative pressures and gauge pressures.
Preferably, the space velocity of the hydrotreating in the step (1) is 0.5-5 h-1E.g. 0.5h-1、1h-1、1.5h-1、2h-1、2.5h-1、3h-1、3.5h-1、4h-1Or 5h-1And the like, but are not limited to the recited values, and other values not recited within the numerical range are also applicable.
Preferably, the hydrotreating in step (1) removes aldehydes, ketones, hydrazones and peroxides from the circulating solvent.
In the invention, after aldehyde and ketone in the circulating solvent are hydrogenated, alcohol is generated and dissolved in the solvent; the hydrazones are obtained in an upstream unit and are removed during the purification of the circulating solvent, and the peroxides can be directly hydro-decomposed.
As a preferable technical scheme of the invention, the rectification treatment in the step (2) comprises a first-stage rectification treatment and a second-stage rectification treatment which are sequentially carried out.
Preferably, the temperature of the first rectification is 100 to 120 ℃, for example, 100 ℃, 105 ℃, 110 ℃, 115 ℃ or 120 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the pressure of the primary rectification treatment is 0.2 to 0.5MPa, for example, 0.2MPa, 0.25MPa, 0.3MPa, 0.35MPa, 0.4MPa, 0.45MPa or 0.5MPa, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the temperature of the second rectification is 120 to 200 ℃, for example, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 180 ℃ or 200 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the pressure of the secondary distillation is 0.6 to 1.0MPa, such as 0.6MPa, 0.7MPa, 0.75MPa, 0.8MPa, 0.9MPa or 1.0MPa, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
In the invention, the temperature and pressure of the second-stage rectification treatment are higher than those of the first-stage rectification treatment, the setting of the process parameters can realize that different substances can be rectified and separated at proper temperature, and the two-stage rectification treatment has more flexible operation, high precision and low energy consumption.
Preferably, the purity of the recycled solvent in the top stream of each of the first and second rectification is greater than 98 wt%, such as 98 wt%, 98.2 wt%, 98.5 wt%, 98.8 wt%, 99 wt%, or 99.5 wt%, and the like, but is not limited to the recited values, and other values not recited within this range are equally applicable.
Preferably, the bottom stream after the secondary rectification is an aqueous solution.
In the invention, the bottom material flow after rectification separation is mainly water, and simultaneously contains a small amount of reaction byproducts such as propylene glycol, propylene glycol ether and the like.
As a preferable technical scheme of the invention, the cooling medium used for cooling in the step (3) comprises air or circulating water.
In the invention, the cooler can be selected from common air coolers, evaporative air coolers, water coolers and other cooling equipment.
Preferably, the temperature of the recycled solvent after cooling in step (3) is 15 to 40 ℃, for example 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃ or 40 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferable technical scheme of the invention, the ion exchange resin used in the ion exchange treatment in the step (3) comprises an anion exchange resin and a cation exchange resin, wherein the cation exchange resin comprises a sulfonic acid group cation exchange resin and a carboxylic acid group cation exchange resin, and the anion exchange resin comprises a quaternary amine group anion exchange resin.
Preferably, the temperature of the ion exchange treatment in step (3) is 15 to 40 ℃, for example, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃ or 40 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the pressure of the ion exchange treatment in step (3) is 0.3 to 1.0MPa, such as 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.8MPa or 1.0MPa, but not limited to the recited values, and other values not recited in the above range are also applicable.
Preferably, the space velocity of the circulating solvent in the step (3) is 0.5-4.0 h-1E.g. 0.5h-1、1.0h-1、1.5h-1、2.0h-1、2.5h-1、3.0h-1、3.5h-1Or 4.0h-1And the like, but are not limited to the recited values, and other values not recited within the numerical range are also applicable.
Preferably, the ion exchange treatment in step (3) removes amines, polymers and acid ions in the circulating solvent.
In the present invention, the impurities removed by the ion exchange treatment are mainly generated by the upstream unit.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the device, various impurity components generated in the production process of the propylene oxide are removed through the arrangement of units such as hydrogenation, rectification, ion exchange and the like, the total content of impurities is reduced to below 10ppm, and the purification, purification and recovery of a circulating solvent are realized;
(2) according to the invention, through purification and recovery of the circulating solvent, the influence of the existence of impurities on the service life of the catalyst when the circulating solvent returns to the reaction unit is avoided, the regeneration period of the catalyst reaches more than 4000 hours, and the selectivity of propylene oxide generated by reaction can reach more than 96.5%;
(3) the device provided by the invention is simple in structure, simple and convenient to operate, low in device and operation cost, suitable for removing various impurities and high in economic benefit.
Drawings
FIG. 1 is a schematic structural diagram of a purification and recovery apparatus for a recycled solvent in a propylene oxide production process, provided in example 1 of the present invention;
the system comprises a hydrogenation unit 1, a rectification unit 2, a first rectification tower 21, a second rectification tower 22, a cooling unit 3, a first cooler 31, a second cooler 32 and an ion exchange unit 4.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.
The specific embodiment of the invention provides a device and a method for purifying and recovering a circulating solvent in the production process of propylene oxide, wherein the device for purifying and recovering the circulating solvent comprises a hydrogenation unit 1, a rectification unit 2, a cooling unit 3 and an ion exchange unit 4, the bottom outlet of the hydrogenation unit 1 is connected with the inlet of the rectification unit 2, and the top outlet of the rectification unit 2 is sequentially connected with the cooling unit 3 and the ion exchange unit 4.
The following are typical but non-limiting examples of the invention:
example 1:
the embodiment provides a purification and recovery device for a circulating solvent in the production process of propylene oxide, the structural schematic diagram of the purification and recovery device is shown in fig. 1, and the purification and recovery device comprises a hydrogenation unit 1, a rectification unit 2, a cooling unit 3 and an ion exchange unit 4, wherein the bottom outlet of the hydrogenation unit 1 is connected with the inlet of the rectification unit 2, and the top outlet of the rectification unit 2 is sequentially connected with the cooling unit 3 and the ion exchange unit 4.
The hydrogenation unit 1 comprises a hydrotreater, and a circulating solvent inlet and a hydrogen inlet are arranged on the hydrotreater; the hydrotreater is an ebullated bed reactor.
The rectifying unit 2 sequentially comprises a first rectifying tower 21 and a second rectifying tower 22, and the bottom outlet of the first rectifying tower 21 is connected with the inlet of the second rectifying tower 22.
The first rectifying tower 21 and the second rectifying tower 22 are both plate towers, the number of theoretical plates of the first rectifying tower 21 is 30, and the number of theoretical plates of the second rectifying tower 22 is 40.
The cooling unit 3 comprises a first cooler 31 and a second cooler 32, the top outlet of the first rectifying tower 21 is connected with the inlet of the first cooler 31, the top outlet of the second rectifying tower 22 is connected with the inlet of the second cooler 32, and the outlets of the first cooler 31 and the second cooler 32 are connected with the inlet of the ion exchange unit 4.
The ion exchange unit 4 comprises 2 ion exchangers arranged in parallel, and ion exchange resin is filled in the ion exchangers.
Example 2:
the embodiment provides a purification and recovery device of a circulating solvent in an epoxy propane production process, the purification and recovery device comprises a hydrogenation unit 1, a rectification unit 2, a cooling unit 3 and an ion exchange unit 4, the bottom outlet of the hydrogenation unit 1 is connected with the inlet of the rectification unit 2, and the top outlet of the rectification unit 2 is sequentially connected with the cooling unit 3 and the ion exchange unit 4.
The hydrogenation unit 1 comprises a hydrotreater, and a circulating solvent inlet and a hydrogen inlet are arranged on the hydrotreater; the hydrotreater is a combination of a fixed bed reactor and a slurry bed reactor.
The rectifying unit 2 sequentially comprises a first rectifying tower 21 and a second rectifying tower 22, and the bottom outlet of the first rectifying tower 21 is connected with the inlet of the second rectifying tower 22.
The first rectifying tower 21 is a plate tower, the second rectifying tower 22 is a packed tower, the number of theoretical plates of the first rectifying tower 21 is 45, and the number of theoretical plates of the second rectifying tower 22 is 30.
The cooling unit 3 comprises a cooler, and the top outlets of the first rectifying tower 21 and the second rectifying tower 22 are connected with the inlet of the cooler.
The ion exchange unit 4 comprises 3 ion exchangers arranged in series, and ion exchange resins are filled in the ion exchangers.
Example 3:
the embodiment provides a purification and recovery device of a circulating solvent in an epoxy propane production process, the purification and recovery device comprises a hydrogenation unit 1, a rectification unit 2, a cooling unit 3 and an ion exchange unit 4, the bottom outlet of the hydrogenation unit 1 is connected with the inlet of the rectification unit 2, and the top outlet of the rectification unit 2 is sequentially connected with the cooling unit 3 and the ion exchange unit 4.
The hydrogenation unit 1 comprises a hydrotreater, and a circulating solvent inlet and a hydrogen inlet are arranged on the hydrotreater; the hydrotreater is a suspended bed reactor.
The rectifying unit 2 sequentially comprises a first rectifying tower 21 and a second rectifying tower 22, and the bottom outlet of the first rectifying tower 21 is connected with the inlet of the second rectifying tower 22.
The first rectifying tower 21 is a packed tower, the second rectifying tower 22 is a packed tower, the number of theoretical plates of the first rectifying tower 21 is 20, and the number of theoretical plates of the second rectifying tower 22 is 50.
The cooling unit 3 comprises a first cooler 31 and a second cooler 32, the top outlet of the first rectifying tower 21 is connected with the inlet of the first cooler 31, the top outlet of the second rectifying tower 22 is connected with the inlet of the second cooler 32, and the outlets of the first cooler 31 and the second cooler 32 are connected with the inlet of the ion exchange unit 4.
The ion exchange unit 4 comprises 4 ion exchangers, two of which are connected in series and then are integrally connected in parallel, and the ion exchangers are filled with ion exchange resin.
Example 4:
the embodiment provides a method for purifying and recovering a circulating solvent in the production process of propylene oxide, which is carried out by adopting the device in the embodiment 1 and comprises the following steps:
(1) carrying out hydrogenation treatment on a circulating solvent to be treated, wherein the circulating solvent is a ringThe circulating solvent after separating propylene raw material and epoxypropane product from reaction product of the production process of the epoxypropane mainly comprises methanol, the temperature of the hydrotreatment is 80 ℃, the pressure is 1.0MPa, and the airspeed is 2.5h-1Removing aldehydes, ketones, hydrazones, peroxides and other impurities in the circulating solvent to obtain a hydrogenation material;
(2) sequentially carrying out primary rectification treatment and secondary rectification treatment on the hydrogenated material obtained in the step (1), wherein the temperature of the primary rectification treatment is 110 ℃, the pressure is 0.4MPa, the temperature of the secondary rectification treatment is 160 ℃, and the pressure is 0.8MPa, and separating to obtain a rectified circulating solvent and a rectified water solution;
(3) cooling the rectified circulating solvent obtained in the step (2) by adopting circulating water as a cooling medium, wherein the temperature of the cooled circulating solvent is 25 ℃, and then carrying out ion exchange treatment, wherein the used ion exchange resins are sulfonic cation exchange resin and quaternary ammonium anion exchange resin, the temperature of the ion exchange treatment is 25 ℃, the pressure is 0.8MPa, and the airspeed is 2.5h-1And removing amines, polymers and acid radical ions in the circulating solvent to obtain the purified circulating solvent.
In the embodiment, the device and the method are adopted for purifying and recycling the circulating solvent, the content of impurities in the purified circulating solvent is only 8ppm, wherein the contents of aldehydes and ketones are both 2ppm, the content of peroxides is 2ppm, the content of amines is 1ppm, and the content of polymers is 1 ppm; the circulating solvent is purified and recycled, so that the influence on the catalyst is avoided to be extremely small when the circulating solvent returns to a reaction unit, the regeneration period of the catalyst reaches 4100h, and the selectivity of propylene oxide generated by the reaction is 97%.
Example 5:
the embodiment provides a method for purifying and recovering a circulating solvent in the production process of propylene oxide, which is carried out by adopting the device in the embodiment 2 and comprises the following steps:
(1) carrying out hydrogenation treatment on a circulating solvent to be treated, wherein the circulating solvent is the circulating solvent obtained after a propylene raw material and a propylene oxide product are separated from a reaction product of a propylene oxide production process and mainly comprises methanol, and the hydrogenated circulating solventThe temperature is 60 ℃, the pressure is 0.6MPa, and the space velocity is 1h-1Removing aldehydes, ketones, hydrazones, peroxides and other impurities in the circulating solvent to obtain a hydrogenation material;
(2) sequentially carrying out primary rectification treatment and secondary rectification treatment on the hydrogenated material obtained in the step (1), wherein the temperature of the primary rectification treatment is 100 ℃, the pressure is 0.5MPa, the temperature of the secondary rectification treatment is 130 ℃, and the pressure is 1.0MPa, and separating to obtain a rectified circulating solvent and a rectified water solution;
(3) cooling the rectified circulating solvent obtained in the step (2) by adopting air as a cooling medium, wherein the temperature of the cooled circulating solvent is 15 ℃, and then carrying out ion exchange treatment, wherein the ion exchange resins are carboxylic acid group cation exchange resin and quaternary ammonium group anion exchange resin, the temperature of the ion exchange treatment is 15 ℃, the pressure is 0.5MPa, and the airspeed is 1.0h-1And removing amines, polymers and acid radical ions in the circulating solvent to obtain the purified circulating solvent.
In this embodiment, the device and the method are used for purifying and recovering the circulating solvent, and the purified circulating solvent has an impurity content of only 9ppm, wherein the aldehyde content is 2ppm, the ketone content is 3ppm, the peroxide content is 2ppm, the amine content is 1ppm, and the polymer content is 1 ppm; the circulating solvent is purified and recycled, so that the influence on the catalyst when the circulating solvent returns to the reaction unit is extremely small, the regeneration period of the catalyst reaches 4050h, and the selectivity of the propylene oxide generated by the reaction is 96.5%.
Example 6:
this example provides a method for purifying and recovering a recycled solvent in a propylene oxide production process, which is performed by using the apparatus in example 3, and comprises the following steps:
(1) carrying out hydrogenation treatment on a circulating solvent to be treated, wherein the circulating solvent is the circulating solvent obtained after a propylene raw material and a propylene oxide product are separated from a reaction product of a propylene oxide production process and mainly comprises methanol, the temperature of the hydrogenation treatment is 110 ℃, the pressure is 0.2MPa, and the airspeed is 5h-1Removing aldehydes, ketones, hydrazones and peroxides from the circulating solventObtaining a hydrogenation material;
(2) sequentially carrying out primary rectification treatment and secondary rectification treatment on the hydrogenated material obtained in the step (1), wherein the temperature of the primary rectification treatment is 120 ℃, the pressure is 0.25MPa, the temperature of the secondary rectification treatment is 200 ℃, and the pressure is 0.6MPa, and separating to obtain a rectified circulating solvent and a rectified water solution;
(3) cooling the rectified circulating solvent obtained in the step (2) by adopting circulating water as a cooling medium, wherein the temperature of the cooled circulating solvent is 40 ℃, and then carrying out ion exchange treatment, wherein the used ion exchange resins are sulfonic cation exchange resin and quaternary ammonium anion exchange resin, the temperature of the ion exchange treatment is 40 ℃, the pressure is 0.3MPa, and the airspeed is 4.0h-1And removing amines, polymers and acid radical ions in the circulating solvent to obtain the purified circulating solvent.
In this embodiment, the device and the method are used for purifying and recovering the circulating solvent, and the content of impurities in the purified circulating solvent is only 8.5ppm, wherein the content of aldehydes is 2ppm, the content of ketones is 2.5ppm, the content of peroxides is 1.5ppm, the content of amines is 1ppm, and the content of polymers is 1.5 ppm; the circulating solvent is purified and recycled, so that the influence on the catalyst when the circulating solvent returns to the reaction unit is extremely small, the regeneration period of the catalyst reaches 4080h, and the selectivity of the propylene oxide generated by the reaction is 96.6%.
Comparative example 1:
this comparative example provides an apparatus and a process for the purification and recovery of a recycled solvent in a propylene oxide production process, with reference to the apparatus of example 1, with the only difference that: excluding hydrogenation unit 1.
The process is referred to the process in example 3, with the only difference that: the recycled solvent is not subjected to hydrotreating, but is directly subjected to rectification treatment.
In the comparative example, the hydrogenation unit is an important unit for removing various impurities, and the hydrogenation unit is not arranged, so that the aldehyde, ketone and peroxide impurities are difficult to remove, and the finally obtained purified solvent has high impurity content, wherein the aldehyde content is 54ppm, the ketone content is 26ppm, the peroxide content is 65ppm, and the polymer content is 12 ppm; due to the high impurity content, the catalyst in the reaction unit is greatly influenced in service life, the regeneration period of the catalyst is only 2000h, the long-period operation is difficult to maintain, and the selectivity of the propylene oxide generated by the reaction is only 91.5%.
Comparative example 2:
this comparative example provides an apparatus and a process for the purification and recovery of a recycled solvent in a propylene oxide production process, with reference to the apparatus of example 1, with the only difference that: ion exchange unit 4 is not included.
The process is referred to the process in example 3, with the only difference that: the circulating solvent is cooled after rectification treatment and is not subjected to ion exchange treatment.
In the comparative example, because the ion exchange unit is an important unit for further removing impurities, especially the hydrogenation unit can generate new impurity types, the impurities need to be removed by ion exchange, the ion exchange unit is not arranged, and the impurities such as amines and polymers are difficult to remove, the finally obtained purified solvent has high impurity content, wherein the aldehyde content is 3ppm, the ketone content is 2ppm, the peroxide content is 6ppm, the amine content is 8ppm, and the polymer content is 12 ppm; due to the high impurity content, the catalyst in the reaction unit is greatly influenced in service life, the regeneration period of the catalyst is only 2800h, the long-period operation is difficult to maintain, and the selectivity of the propylene oxide generated by the reaction is only 92.5%.
It can be seen from the above examples and comparative examples that the apparatus of the present invention removes various impurity components generated in the production process of propylene oxide by the arrangement of units such as hydrogenation, rectification, ion exchange, etc., and the total content of impurities is reduced to below 10ppm, thereby realizing the purification and purification recovery of the circulating solvent; by purifying and recycling the circulating solvent, the influence of the existence of impurities on the service life of the catalyst when the circulating solvent returns to a reaction unit is avoided, the regeneration period of the catalyst reaches more than 4000 hours, and the selectivity of propylene oxide generated by the reaction can reach more than 96.5 percent; the device has the advantages of simple structure, simple and convenient operation of the method, lower device and operation cost, suitability for removing various impurities and high economic benefit.
The applicant states that the present invention is illustrated by the detailed apparatus and method of the present invention through the above embodiments, but the present invention is not limited to the above detailed apparatus and method, i.e. it is not meant to imply that the present invention must be implemented by the above detailed apparatus and method. It will be apparent to those skilled in the art that any modifications to the present invention, equivalents of the means for substitution and addition of means for carrying out the invention, selection of specific means, etc., are within the scope and disclosure of the invention.
Claims (10)
1. The utility model provides a purification recovery unit of circulation solvent in propylene oxide production process which characterized in that, purification recovery unit includes hydrogenation unit, rectifying unit, cooling unit and ion exchange unit, the bottom export of hydrogenation unit links to each other with rectifying unit's entry, rectifying unit's top export and cooling unit, ion exchange unit connect gradually.
2. The purification recovery device of claim 1, wherein the hydrogenation unit comprises a hydrotreater, and the hydrotreater is provided with a circulating solvent inlet and a hydrogen inlet;
preferably, the hydrotreater comprises any one of a fixed bed reactor, a slurry bed reactor, an ebullating bed reactor or a suspended bed reactor, or a combination of at least two of them.
3. The purification and recovery device of claim 1 or 2, wherein the rectification unit comprises a first rectification tower and a second rectification tower in sequence, and a bottom outlet of the first rectification tower is connected with an inlet of the second rectification tower;
preferably, the first rectification column and the second rectification column are independently a plate column or a packed column;
preferably, the theoretical plate number of the first rectifying tower is 20-50;
preferably, the theoretical plate number of the second rectifying tower is 30-50.
4. The purification and recovery device of any one of claims 1 to 3, wherein the cooling unit comprises a cooler, and the top outlets of the first rectifying tower and the second rectifying tower are connected with the inlet of the cooler;
preferably, the cooling unit comprises a first cooler and a second cooler, the top outlet of the first rectifying tower is connected with the inlet of the first cooler, the top outlet of the second rectifying tower is connected with the inlet of the second cooler, and the outlets of the first cooler and the second cooler are both connected with the inlet of the ion exchange unit.
5. The purification recovery device of any one of claims 1 to 4, wherein the ion exchange unit comprises at least 2 ion exchangers;
preferably, the ion exchangers are arranged in series and/or in parallel;
preferably, the ion exchanger is packed with an ion exchange resin.
6. A method for recycling a solvent purge using the apparatus of any of claims 1-5, comprising the steps of:
(1) carrying out hydrogenation treatment on the circulating solvent to be treated to obtain a hydrogenation material;
(2) rectifying the hydrogenation material obtained in the step (1), and separating to obtain a rectified circulating solvent and a rectified water solution;
(3) and (3) cooling the rectified circulating solvent obtained in the step (2) and then carrying out ion exchange treatment to obtain the purified circulating solvent.
7. The method according to claim 6, wherein the recycled solvent to be treated in step (1) is recycled solvent after separating propylene raw material and propylene oxide product from reaction product of propylene oxide production process;
preferably, the composition of the recycled solvent of step (1) comprises mainly methanol;
preferably, the temperature of the hydrotreatment in the step (1) is 50-110 ℃;
preferably, the pressure of the hydrotreating in the step (1) is 0.1-1.0 MPa;
preferably, the space velocity of the hydrotreating in the step (1) is 0.5-5 h-1；
Preferably, the hydrotreating in step (1) removes aldehydes, ketones, hydrazones and peroxides from the circulating solvent.
8. The method according to claim 6 or 7, wherein the rectification process of the step (2) comprises a primary rectification process and a secondary rectification process which are sequentially carried out;
preferably, the temperature of the primary rectification treatment is 100-120 ℃;
preferably, the pressure of the primary rectification treatment is 0.2-0.5 MPa;
preferably, the temperature of the secondary rectification treatment is 120-200 ℃;
preferably, the pressure of the secondary rectification treatment is 0.6-1.0 MPa;
preferably, the purity of the recycled solvent in the top streams of the first and second rectification is greater than 98 wt%;
preferably, the bottom stream after the secondary rectification is an aqueous solution.
9. The method according to any one of claims 6 to 8, wherein the cooling medium used for the cooling in step (3) comprises air or circulating water;
preferably, the temperature of the cooled circulating solvent in the step (3) is 15-40 ℃.
10. The method according to any one of claims 6 to 9, wherein the ion exchange resin used for the ion exchange treatment in step (3) comprises an anion exchange resin and a cation exchange resin;
preferably, the temperature of the ion exchange treatment in the step (3) is 15-40 ℃;
preferably, the pressure of the ion exchange treatment in the step (3) is 0.3-1.0 MPa;
preferably, the space velocity of the circulating solvent in the step (3) is 0.5-4.0 h-1；
Preferably, the ion exchange treatment in step (3) removes amines, polymers and acid ions in the circulating solvent.
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Cited By (1)
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| CN115068966A (en) * | 2022-08-22 | 2022-09-20 | 淄博鲁华泓锦新材料集团股份有限公司 | Continuous desolventizing and refining method for hydrogenated petroleum resin |
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