CN114763333B - Separation and recovery method of peroxide TBHP and byproduct TBA in epoxy phenylethane mother liquor - Google Patents

Separation and recovery method of peroxide TBHP and byproduct TBA in epoxy phenylethane mother liquor Download PDF

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CN114763333B
CN114763333B CN202110053639.6A CN202110053639A CN114763333B CN 114763333 B CN114763333 B CN 114763333B CN 202110053639 A CN202110053639 A CN 202110053639A CN 114763333 B CN114763333 B CN 114763333B
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tba
tbhp
peroxide
byproduct
falling film
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CN114763333A (en
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郭爱国
王静
刘盼盼
罗静
胡展
于天勇
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Wanhua Chemical Group Co Ltd
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Wanhua Chemical Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C407/00—Preparation of peroxy compounds
    • C07C407/003—Separation; Purification; Stabilisation; Use of additives
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
    • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/32—Separation; Purification
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
    • C07D303/02—Compounds containing oxirane rings
    • C07D303/04—Compounds containing oxirane rings containing only hydrogen and carbon atoms in addition to the ring oxygen atoms
    • 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

Abstract

The invention provides a method for separating and recovering peroxide TBHP and byproduct TBA in an epoxy phenylethane mother solution. The tower top light component after the crude product of the ethylene oxide is separated by vacuum rectification is subjected to falling film crystallization, melting sweating and melting treatment in sequence, and finally, the sweating liquid and the melting liquid are collected, and the peroxide TBHP and the byproduct TBA with high purity are recovered, so that the method has the characteristics of safety, energy conservation, simplicity and high efficiency.

Description

Separation and recovery method of peroxide TBHP and byproduct TBA in epoxy phenylethane mother liquor
Technical Field
The invention belongs to the technical field of preparation of ethylene oxide, and relates to a separation method of peroxide tert-butyl hydroperoxide TBHP and tert-butyl alcohol TBA byproducts in an ethylene oxide mother solution.
Background
The styrene oxide is also called styrene oxide, is an important organic synthesis intermediate, can be used for producing epoxy resin, UV absorbent and the like, is also an important raw material in the pharmaceutical and spice industries, is used for preparing beta-phenethyl alcohol, levamisole and the like, and has the situation of increasing market demands for the styrene oxide in recent years.
The synthesis method of the epoxy phenylethane mainly comprises a halohydrin method, a peroxy acid oxidation method, a direct oxidation method and the like. In recent years, under the premise of increasingly strict environmental protection requirements, the research on the preparation of the ethylene oxide by the direct oxidation method is receiving a great deal of attention. The oxidizing agent commonly used in the direct oxidation process is H 2 O 2 Tert-butyl hydroperoxide (TBHP), ethylbenzene hydroperoxide (EBHP), cumene Hydroperoxide (CHP), O 2 Etc. When the organic peroxide is an oxidant, the whole process of the process flow is anhydrous operation, no waste water is generated, and the whole process is environment-friendly due to extremely high reaction selectivity and extremely small waste liquid amount, so that the process is a more environment-friendly process which is researched at present.
Styrene and peroxide are used as raw materials to produce the epoxy phenylethane through epoxidation reaction, and the reaction mother liquor contains crude epoxy phenylethane with the mass percent of 15-30 percent, and residual peroxide raw materials such as TBHP or excessive styrene and byproduct Tertiary Butyl Alcohol (TBA) which are not completely reacted. As the byproduct TBA materials after the epoxidation reaction contain organic acid esters, peroxides and other impurities, the byproduct TBA materials can have adverse effects on downstream applications such as MMMA, MTBE synthesis and the like. Thus, the TBA is purified to remove impurities before entering downstream synthesis units. However, no mature and reliable separation technology exists at present in the purification of TBA byproducts from the production of ethylene oxide by epoxidation.
Ji Gongbing et al in CN108440246a propose a method for separating t-butanol, which aims at the problem that t-butanol and di-t-butyl peroxide form an azeotropic mixture which is difficult to separate, and the separation of t-butanol is achieved by adding an extractant. Because the extractant is introduced, the process is complex, the later extractant is recycled, and the energy consumption is high.
Zhang Xinwei et al in CN111097510a propose a method for removing impurities such as lower alcohols, polyols, organic peroxides, organic acid esters and the like in TBA by using a catalyst, and the method has the advantages of complicated catalyst preparation process, high cost, environmental pollution caused by solid waste catalyst, high reactor operation temperature and pressure and high safety risk.
He Lei et al in CN104926760a propose a method for synthesizing ethylene oxide by using ozone as an oxidant, after the reaction is completed, sodium bisulphite is added to remove the peroxy value, this step generates alkaline waste liquid, then the ethylene oxide product is separated by distillation under reduced pressure, which is a conventional separation means, requires a vacuum pump to maintain the vacuum degree and consumes more evacuation energy, and is not economical.
Dong Yining et al in CN104926760A provide a method for separating phenylethane and phenylacetaldehyde at low temperature, and design a combination process of cryogenic crystallization and vacuum rectification according to the different melting points of phenylethane and phenylacetaldehyde. However, the system only mentions the separation of two isomers, and the crystallizer adopts an ethylene refrigeration cooling means, so that the conditions are more severe and the energy consumption is high.
In addition, the mother liquor for producing the ethylene oxide by the epoxidation reaction by using styrene and peroxide TBHP as raw materials also contains excessive organic peroxide raw materials such as Tertiary Butyl Hydroperoxide (TBHP), di-tertiary butyl peroxide (DTBP) and the like.
Peroxide is known to be a heat-sensitive substance, and high-temperature concentration involves a risk of self-decomposition, and is prone to explosion. The temperature of the tower bottom of the rectifying tower can be reduced by adopting reduced pressure rectification in the TBHP refining tower, but the risk of high local concentration of TBHP in the TBHP refining tower is still avoided, and the size of the rectifying tower is very large, so that the investment of equipment can be increased. Thus, rectification under reduced pressure is not the optimal method for separating residual peroxide TBHP from the ethylene oxide system. No method has been found in the prior art which can effectively separate peroxide for recovery.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a separation and recovery method of peroxide TBHP (tertiary butyl hydroperoxide) and byproduct TBA (tertiary butyl alcohol) in an epoxy phenylethane mother solution. The tower top light component after the crude product of the ethylene oxide is separated by vacuum rectification is subjected to falling film crystallization, melting sweating and melting treatment in sequence, and finally, the sweating liquid and the melting liquid are collected, and the peroxide TBHP and the byproduct TBA with high purity are recovered, so that the method has the characteristics of safety, energy conservation, simplicity and high efficiency.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the invention provides a separation and recovery method of peroxide TBHP and byproduct TBA in an epoxy phenylethane mother solution, which comprises the following steps:
1) The ethylene oxide mother liquor is separated by rectification, light components containing TBA and TBHP are obtained from the top of a rectifying tower, and an ethylene oxide crude product is obtained from the bottom of the rectifying tower;
2) Crystallizing TBA and TBHP from light components containing TBA and TBHP through a falling film crystallizer, and separating the light components from uncrystallized impurity raffinate to obtain a mixture crystallization layer of TBA and TBHP;
3) Heating to 20-25 ℃ at a speed of 1-2 ℃/min in a falling film crystallizer, preserving heat for 5-30 min, melting and sweating a mixture crystallization layer of TBA and TBHP, and collecting sweat to obtain recovered peroxide TBHP;
4) Continuously heating to 25-30 ℃ in the falling film crystallizer, preserving heat until the crystallization layer is completely melted, and collecting the melt, namely the recovered byproduct TBA.
In the step 1), styrene and peroxide TBHP are used as raw materials to prepare the ethylene oxide through epoxidation reaction, the ethylene oxide mother liquor contains 20-30% of ethylene oxide, 25-35% of TBA, 0.5-2% of TBHP, 35-46% of STN (styrene) and 0.2-0.6% of impurities, wherein the impurities comprise MEK (methyl ethyl ketone), IPA (isopropanol), TBF (tert-butyl formate), DTBP (di-tert-butyl peroxide), IBA (isobutanol), IBF (isobutyl formate) and the like, and the contents of the impurities are about MEK 0.01-0.03%, IPA 0.03-0.06%, TBF 0.02-0.04%, DTBP 0.03-0.06%, IBA 0.1-0.3% and IBF 0.03-0.05% respectively, based on 100% of total mass.
In the step 1) of the invention, the operation pressure of the rectifying tower is 20-30 kpa A, the temperature of the top of the tower is 35-42 ℃, and the temperature of the bottom of the tower is 117-124 ℃.
In the step 1) of the invention, the light component containing TBA and TBHP comprises 92-98% of TBA, 1.5-6% of TBHP and 0.59-1.8% of impurities, wherein the impurity composition comprises 0.02-0.1% of MEK, 0.08-0.2% of IPA, 0.05-0.13% of TBF, 0.06-0.2% of DTBP, 0.3-1% of IBA and 0.08-0.15% of IBF, based on 100% of total mass.
The crude product of the epoxy phenylethane mainly comprises the epoxy phenylethane and styrene, wherein the byproduct TBA can be reduced to below 0.6wt%, the peroxide TBHP can be reduced to below 0.05wt%, and the crude product is directly sent to a downstream refining unit.
In the step 2) of the invention, the falling film is crystallized at the temperature of-20 to 0 ℃, preferably-10 to-5 ℃; the crystallization time is 5 to 25s, preferably 10 to 20s;
preferably, the falling film crystallizer is a jacketed crystallizer, and a feed liquid distributor and a crystallization pipe are arranged in the falling film crystallizer; the length of the crystallization tube is 1.5-30 m, preferably 5-12 m, and the diameter is 25-75 mm, preferably 38-57 mm;
the falling film crystallizer is of a single tube type or a tube type, preferably a tube type;
more preferably, the falling film crystallizer is selected from the MWB crystallizer of Sulzer company, etc.
In the step 2) of the invention, the light component containing TBA and TBHP flows down from the upper part of the crystallizer along the inner wall of the crystallization tube by gravity and flows in parallel with the refrigerant, so that the heat transfer temperature difference between the upper and lower sides of the crystallizer is reduced, and the crystallization is more uniform;
preferably, the light fraction comprising TBA and TBHP flows along the inner wall of the crystallization tube at a rate of between 0.3m/s and 1.2m/s, preferably between 0.5m/s and 1m/s; the light component enters a crystallization tube with the flow rate, the length of the crystallization tube is 1.5-30 m, preferably 5-12 m, so that TBA and TBHP can be completely crystallized within 5-25 s, preferably 10-20 s, and then impurity residual liquid is separated and removed.
Preferably, the refrigerant is an aqueous solution containing 30 to 50wt% ethylene glycol.
In the step 2), the mixture crystallization layer of the TBA and the TBHP comprises 93 to 98.1 percent of TBA, 1.5 to 6 percent of TBHP and 0.018 to 0.045 percent of impurity, wherein the impurity composition comprises 0.01 to 0.025 percent of TBF and 0.008 to 0.02 percent of DTBP, based on 100 percent of total mass.
The impurity raffinate is the residual component after separating out the crystallization mixture of TBA and TBHP from the light component containing TBA and TBHP, and MEK, IPA, TBF, DTBP, IBA, IBF and other impurities in the product to be recovered can be basically removed after the step 2) of falling film crystallization treatment.
In step 3) of the present invention, the recovered peroxide TBHP (i.e., sweat) comprises, based on 100% by weight of total TBHP crystals, partially melted TBA crystals, and entrained liquid impurities comprising 60 to 82% TBHP, 15 to 40% TBA, and 0.5 to 0.85% impurities, said impurities comprising a TBF of 0.25 to 0.4% and a DTBP of 0.25 to 0.45%.
In the step 4) of the invention, the purity of the byproduct TBA is more than 99.9 weight percent, and the content of peroxide TBHP is reduced to below 600 ppm.
The purity of the byproduct TBA recovered by the method is more than 99.9wt percent, the impurity content is low, and the method can be directly used for synthesizing downstream MMMA, MTBE and the like.
The purity of the peroxide TBHP recovered by the method is 60-82 wt%, and the peroxide TBHP contains a small amount of TBA and a small amount of impurities TBF and DTBP, and can be recycled to the reaction kettle to continuously participate in the epoxidation reaction.
The method of the invention has the advantages that the recovery rate of the byproduct TBA can reach more than 96 percent based on the initial content of the ethylene oxide mother liquor, and the proportion of the peroxide TBHP capable of being recycled is more than 96 percent.
Since byproduct TBA recovered from the epoxidation of styrene and peroxide as starting materials contains various impurities, such as tert-butyl formate (TBF), organic peroxide impurities such as tert-butyl hydroperoxide (TBHP), di-tert-butyl peroxide (DTBP), and low carbon alcohol impurities such as isopropanol, which adversely affect downstream processes, the impurities must be removed before entering the downstream processes. The peroxide is a thermosensitive substance, and the high-temperature concentration has self-decomposition risk, is easy to cause explosion, and has the problems of difficult separation and recovery of peroxide and difficult refining of TBA.
The invention separates and recovers peroxide TBHP in mother liquor by utilizing the technical principle of combining melt crystallization and rectification, avoids the risk of explosion caused by high-temperature pyrolysis in the process of concentrating peroxide, removes impurities in TBA by utilizing the difference between the impurities and the solidifying point of TBA to obtain high-purity TBA byproducts, and realizes safe, energy-saving, simple and efficient recovery of peroxide and byproduct TBA.
Compared with the prior art, the invention has the beneficial effects that:
the separation method not only avoids the risk of explosion caused by high-temperature pyrolysis in the process of rectifying and separating peroxide, and belongs to an intrinsically safe process, but also removes impurities in TBA to obtain a high-purity TBA byproduct; the TBHP separated by crystallization can be recycled, and the economic benefit is remarkable; the purity of the obtained TBA byproduct can reach 99.9wt percent, the impurity content is low, the method can be directly used for synthesizing downstream MMMA, MTBE and the like, the problems that TBHP in the current ethylene oxide mother liquor is difficult to separate and the byproduct TBA is refined are solved, and the safe, energy-saving, simple and efficient recovery of peroxide and the byproduct TBA is realized.
Detailed Description
The technical scheme of the invention is described in detail below with reference to specific embodiments.
The ethylene oxide mother liquor adopted in the embodiment of the invention is prepared from the following materials of STN and TBHP by epoxidation reaction to produce ethylene oxide, wherein the ethylene oxide mother liquor comprises 20-30% of ethylene oxide, 25-35% of TBA, 0.5-2% of TBHP, 35-46% of STN, 0.01-0.03% of MEK, 0.03-0.06% of IPA, 0.02-0.04% of TBF, 0.03-0.06% of DTBP, 0.1-0.3% of IBA and 0.03-0.05% of IBF by total mass.
The method of the embodiment of the invention adopts the equipment that:
light component removal column (rectifying column): the manufacturer is Sulzer company, a packed tower and a theoretical plate number of 20;
falling film crystallizer: the MWB crystallizer is a jacketed column Guan Jiejing crystallizer, and is internally provided with a feed liquid distributor and a crystallization tube, wherein the length of the crystallization tube is 10m, and the diameter of the crystallization tube is 45mm.
Example 1
The separation and recovery method of peroxide TBHP and byproduct TBA in the ethylene oxide mother liquor comprises 28% of ethylene oxide, 35% of TBA, 0.7% of TBHP, 36.024% of STN and 0.276% of impurity (MEK 0.012% of impurity, 0.034% of IPA, 0.023% of TBF, 0.032% of DTBP, 0.14% of IBA and 0.035% of IBF).
The method comprises the following steps:
1) The ethylene oxide mother liquor (40 ℃ C., feed rate 2417.5 kg/hr) enters a rectifying tower for rectification separation, the operating pressure of the rectifying tower is 20kpa A, the temperature of the tower top is 35.6 ℃ C., the temperature of the tower bottom is 118.2 ℃ C., light components (860.70 kg/hr) containing TBA and TBHP are obtained from the tower top, and the rest heavy component ethylene oxide crude product leaves the rectifying tower from the tower bottom and is directly sent to a downstream refining unit;
the light fraction comprising TBA and TBHP, based on 100% of its total mass, comprises 97.3% TBA, 1.9% TBHP, and 0.8% impurities (impurity composition including MEK 0.0334%, IPA 0.0945%, TBF 0.064%, DTBP 0.0854%, IBA 0.4%, IBF 0.0954%).
2) Introducing light components (860.70 kg) containing TBA and TBHP into a falling film crystallizer, flowing down the inner wall of the crystallizer at a flow rate of 0.5m/s from the upper part of the crystallizer by virtue of gravity and flowing in parallel with a water solution of 35wt% of ethylene glycol serving as a refrigerant, controlling the temperature of the falling film crystallization process to be-10 ℃, crystallizing for 20s to enable the TBA and the TBHP to be completely crystallized, and separating and removing uncrystallized impurity residual liquid (16.49 kg) to obtain a mixture crystallization layer of the TBA and the TBHP;
the mixture crystal layer of TBA and TBHP comprises TBA 98.033%, TBHP 1.945% and impurity 0.022% (comprising TBF 0.013% and DTBP 0.009%) based on 100% of total mass.
3) Heating to 20 ℃ at a speed of 1-2 ℃/min in a falling film crystallizer, preserving heat for 20min, melting and sweating a mixture crystallization layer of TBA and TBHP, and collecting sweat to obtain recovered peroxide TBHP (26.37 kg);
recovered peroxide TBHP (i.e., perspiration) contained TBHP 61.70%, TBA 37.66%, impurity 0.64% (including TBF 0.34%, DTBP 0.3%).
4) Continuously heating to 25-30 ℃ in the falling film crystallizer, preserving heat until the residual crystallization layer is completely melted, and collecting the melt, namely the recovered byproduct TBA (817.84 kg). The by-product TBA purity was 99.98wt% and the peroxide TBHP content was reduced to 181ppm.
The recovery rate of the byproduct TBA was 96.64% and the proportion of the peroxide TBHP that could be recycled was 96.14% based on the initial content in the ethylene oxide mother liquor.
Example 2
The separation and recovery method of peroxide TBHP and byproduct TBA in the ethylene oxide mother liquor comprises 26% of ethylene oxide, 31% of TBA, 1.2% of TBHP, 41.434% of STN and 0.366% of impurity (the impurity comprises MEK 0.018%, IPA 0.042%, TBF 0.033%, DTBP 0.043%, IBA 0.19% and IBF 0.04%).
The method comprises the following steps:
1) The ethylene oxide mother liquor (40 ℃ C., feed rate 1934 kg/hr) enters a rectifying tower for rectifying and separating, the operating pressure of the rectifying tower is 20kpa A, the temperature of the tower top is 35.8 ℃ C., the temperature of the tower bottom is 118.4 ℃ C., light components (623.14 kg/hr) containing TBA and TBHP are obtained from the tower top, and the rest heavy component ethylene oxide crude product leaves the rectifying tower from the tower bottom and is directly sent to a downstream refining unit;
the light fraction comprising TBA and TBHP, based on 100% of its total mass, comprises 95.25% TBA, 3.65% TBHP, and 1.1% impurities (impurity composition comprising MEK 0.0553%, IPA 0.1%, TBF 0.1%, DTBP 0.1%, IBA 0.6%, IBF 0.1%).
2) Introducing light components (623.14 kg) containing TBA and TBHP into a falling film crystallizer, flowing down the inner wall of the crystallizer at a flow rate of 0.7m/s from the upper part of the crystallizer by means of gravity and flowing in parallel with 40wt% of glycol aqueous solution serving as a refrigerant, controlling the temperature of the falling film crystallization process to be-8 ℃ and the crystallization time to be 14.3s so as to completely crystallize the TBA and the TBHP, and separating and removing uncrystallized impurity residual liquid (14.55 kg) to obtain a mixture crystallization layer of the TBA and the TBHP;
the mixture crystallization layer of TBA and TBHP comprises TBA 96.26%, TBHP 3.7% and impurity 0.04% (including TBF 0.021% and DTBP 0.019%) based on 100% of the total mass.
3) Heating to 22 ℃ at a speed of 1-2 ℃/min in a falling film crystallizer, preserving heat for 20min, melting and sweating a mixture crystallization layer of TBA and TBHP, and collecting sweat to obtain recovered peroxide TBHP (29.59 kg);
recovered peroxide TBHP (i.e., perspiration) contained TBHP 75.47%, TBA 23.75%, impurity 0.78% (including TBF 0.38%, DTBP 0.4%).
4) And continuously heating to 25 ℃ in the falling film crystallizer, preserving heat until the residual crystallization layer is completely melted, and collecting the melt, namely the recovered byproduct TBA (579 kg). The by-product TBA purity was 99.97wt% and the peroxide TBHP content was reduced to 311ppm.
The recovery rate of the byproduct TBA was 96.54% and the proportion of the peroxide TBHP that could be recycled was 96.24% based on the initial content in the styrene oxide mother liquor.
Example 3
The separation and recovery method of peroxide TBHP and byproduct TBA in the ethylene oxide mother liquor comprises 24% of ethylene oxide, 28% of TBA, 1.6% of TBHP, 45.896% of STN and 0.504% of impurity (the impurity comprises MEK 0.027%, IPA 0.055%, TBF 0.039%, DTBP 0.057%, IBA 0.28% and IBF 0.046%).
The method comprises the following steps:
1) The ethylene oxide mother liquor (40 ℃ C., feed rate 1450.5 kg/hr) enters a rectifying tower for rectification separation, the operating pressure of the rectifying tower is 20kpa A, the temperature of the tower top is 36.1 ℃ C., the temperature of the tower bottom is 118.7 ℃ C., light components (431.89 kg/hr) containing TBA and TBHP are obtained from the tower top, and the rest heavy component ethylene oxide crude product leaves the rectifying tower from the tower bottom and is directly sent to a downstream refining unit;
the light component comprising TBA and TBHP comprises 93.1% TBA, 5.266% TBHP, and 1.634% impurities (including MEK 0.0898%, IPA 0.2%, TBF 0.1%, DTBP 0.2%, IBA 0.9%, IBF 0.1%) based on 100% total mass.
2) Introducing light components (431.89 kg) containing TBA and TBHP into a falling film crystallizer, flowing down the inner wall of the crystallizer at a flow rate of 1m/s from the upper part of the crystallizer by means of gravity and flowing in parallel with 45wt% of glycol aqueous solution of refrigerant, controlling the temperature of the falling film crystallization process to be-5 ℃, crystallizing for 10s to enable the TBA and the TBHP to be completely crystallized, and separating and removing non-crystallized impurity residual liquid (12.36 kg) to obtain a mixture crystallization layer of the TBA and the TBHP;
the mixture crystal layer of TBA and TBHP contained TBA 94.59%, TBHP 5.37% and impurity 0.04% (including TBF 0.0213%, DTBP 0.0187%) by total mass thereof as 100%.
3) Heating to 24 ℃ at a speed of 1-2 ℃/min in a falling film crystallizer, preserving heat for 20min, melting and sweating a mixture crystallization layer of TBA and TBHP, and collecting sweat to obtain recovered peroxide TBHP (26.48 kg);
recovered peroxide TBHP (i.e., perspiration) contained TBHP 84.42%, TBA 14.98%, impurity 0.6% (including TBF 0.3%, DTBP 0.3%).
4) The temperature in the falling film crystallizer is continuously raised to 25 ℃ and kept at the temperature until the residual crystallization layer is completely melted, and the melt is collected to obtain the recovered byproduct TBA (393.05 kg). The purity of the byproduct TBA is more than 99.96wt percent, and the content of peroxide TBHP is reduced to below 401 ppm.
The recovery rate of the byproduct TBA is over 96.7 percent and the proportion of the peroxide TBHP capable of being recycled is 96.3 percent based on the initial content of the epoxy phenylethane mother liquor.
Comparative example 1
Light components comprising TBA and TBHP obtained from the top of step 1) of example 1 were used as starting materials and treated by the following steps:
1) Direct crystallization: the mixture (860.70 kg) withdrawn from the top of the light column was fed into a trough crystallizer (GORE TEX Series 300, sulzer Co.) using chilled water to control the temperature of the system to 8℃to crystallize TBA and peroxide TBHP, after 4 hours of incubation, the uncrystallized impurity raffinate TBHP was collected into a raffinate tank containing TBHP 4.35%, TBA 94.1%, impurity 1.55% (including MEK 0.076%, IPA 0.259%, TBF 0.113%, DTBP 0.193%, IBA 0.694%, IBF 0.215%).
2) Melting: and (3) raising the temperature of the chilled water to above 25 ℃ to enable TBA crystals in the crystallizer to be completely melted, and collecting the melt to a TBA product tank.
Due to the higher entrained impurities, TBA purity was only 98.77wt.%, crystallization separation was 69.3%.
Comparative example 2
With reference to the method of example 1, except that "slowly raise temperature to 20℃at a rate of 3 to 4℃per minute for 20 minutes" in step 3), the perspiration was collected to give recovered peroxide TBHP (132.46 kg) containing TBHP 6.18%, TBA 93.72% and impurity 0.1% (including TBF 0.042% and DTBP 0.058%).
The purity of the byproduct TBA recovered in the step 4) is 98.84wt.%, the crystallization separation rate is only 83.14%, and the purity of TBA is lower due to the fact that the temperature rising rate of the step 3) is faster, the sweating is insufficient, and the sweat entrains more TBA component.
Comparative example 3
With reference to the method of example 1, except that "falling film crystallization process control temperature is 5 ℃ and crystallization time is 20s" in step 2), the uncrystallized impurity raffinate (131.47 kg) was separated and removed to obtain a mixture crystalline layer of TBA and TBHP containing TBA 98.787%, TBHP 1.137%, and impurity 0.076% (including TBF0.0367%, DTBP 0.0393%) by 100% of the total mass.
Step 3) gave recovered peroxide TBHP (22.96 kg) comprising TBHP 35.03%, TBA 62.75%, impurity 2.22% (including TBF0.97%, DTBP 1.25%).
The by-product TBA (706.27 kg) recovered in step 4) was 99.96wt% pure and had a peroxide TBHP content of 352ppm.
The recovery rate of the byproduct TBA was 83.44% based on the initial content of the styrene oxide mother liquor, and the proportion of the peroxide TBHP that could be recycled was 47.53%.
Comparative example 4
The ethylene oxide mother liquor having the same composition as in example 1 was separated by a rectification method, and the steps were:
1) And (3) rectifying: the procedure is as in step 1 of example 1.
2) And (3) secondary rectification: the light components (860.70 kg/hr) comprising TBA and TBHP obtained in step 1) of example 1 were fed to a secondary rectifying column, which was a vacuum rectifying column having a theoretical plate number of 20 and an operating pressure of 20kpa, and column top and column bottom temperatures were 46.8℃and 48.7℃respectively, to continue separation. And (3) obtaining a byproduct TBA at the top of the secondary rectifying tower and obtaining a TBHP mixture at the bottom of the tower.
The purity of the byproduct TBA is 97.72wt%, and the byproduct TBA further comprises 1.66wt% of TBHP and 0.62wt% of impurities (comprising TBF 0.073%, DTBP 0.049%, MEK 0.024%, IPA 0.11%, IBA 0.296% and IBF 0.068%);
the TBHP mixture comprises, by mass, 96.41% of TBA, 2.54% of TBHP, and 1.05% of impurities (including TBF 0.042%, DTBP 0.169%, MEK 0.055%, IPA 0.062%, IBA 0.565% and IBF 0.157%).
Because the boiling points of the components are relatively close, the purity of the byproduct TBA is only 97.72 percent, the recovery rate of the byproduct TBA is only 69.3 percent based on the initial content of the ethylene oxide mother liquor, and the proportion of the peroxide TBHP capable of being recycled is 39.2 percent.

Claims (14)

1. The separation and recovery method of peroxide TBHP and byproduct TBA in the epoxy phenylethane mother liquor is characterized by comprising the following steps:
1) The ethylene oxide mother liquor is separated by rectification, light components containing TBA and TBHP are obtained from the top of a rectifying tower, and an ethylene oxide crude product is obtained from the bottom of the rectifying tower;
2) Crystallizing TBA and TBHP from light components containing TBA and TBHP through a falling film crystallizer, and separating the light components from uncrystallized impurity raffinate to obtain a mixture crystallization layer of TBA and TBHP;
3) Heating to 20-25 ℃ at a speed of 1-2 ℃/min in a falling film crystallizer, preserving heat for 5-30 min, melting and sweating a mixture crystallization layer of TBA and TBHP, and collecting sweat to obtain recovered peroxide TBHP;
4) Continuously heating to 25-30 ℃ in the falling film crystallizer, preserving heat until the crystallization layer is completely melted, and collecting the melt, namely the recovered byproduct TBA.
2. The method according to claim 1, wherein in step 1), the ethylene oxide mother liquor contains 20 to 30% of ethylene oxide, 25 to 35% of TBA, 0.5 to 2% of TBHP, 35 to 46% of STN, and 0.2 to 0.6% of impurities, based on 100% of the total mass, wherein the impurity composition comprises 0.01 to 0.03% of MEK, 0.03 to 0.06% of IPA, 0.02 to 0.04% of TBF, 0.03 to 0.06% of DTBP, 0.1 to 0.3% of IBA, and 0.03 to 0.05% of IBF.
3. The process according to claim 1, wherein in step 1), the rectification is operated at a pressure of 20 to 30kpa, a column top temperature of 35 to 42 ℃, and a column bottom temperature of 117 to 124 ℃;
the light component containing TBA and TBHP comprises 92-98% of TBA, 1.5-6% of TBHP and 0.59-1.8% of impurities, wherein the impurity composition comprises 0.02-0.1% of MEK, 0.08-0.2% of IPA, 0.05-0.13% of TBF, 0.06-0.2% of DTBP, 0.3-1% of IBA and 0.08-0.15% of IBF, based on 100% of total mass.
4. The method according to claim 1, wherein in step 2), the falling film is crystallized at a temperature of-20 to 0 ℃ for a time of 5 to 25s.
5. The method of claim 4, wherein the falling film is crystallized at a temperature of-10 to-5 ℃ for a time of 10 to 20s.
6. The method according to claim 1, wherein in the step 2), the falling film crystallizer is a jacketed crystallizer, and a feed liquid distributor and a crystallization tube are arranged inside the falling film crystallizer; the length of the crystallization tube is 1.5-30 m, and the diameter is 25-75 mm;
the falling film crystallizer is of a single tube type or a tube type.
7. The method according to claim 6, wherein the length of the crystallization tube is 5-12 m and the diameter is 38-57 mm.
8. The method according to claim 1, wherein in step 2), the light components comprising TBA and TBHP flow down the inner wall of the crystallization tube from the upper part of the crystallizer by gravity and flow in parallel with the refrigerant.
9. The process of claim 8, wherein the light components comprising TBA and TBHP flow at a rate of 0.3m/s to 1.2m/s along the inner wall of the crystallization tube.
10. The process of claim 9, wherein the light component comprising TBA and TBHP flows at a rate of 0.5m/s to 1m/s along the inner wall of the crystallization tube.
11. The method of claim 8, wherein the cryogen is an aqueous solution containing 30-50 wt% ethylene glycol.
12. The method according to claim 1, wherein in step 2), the mixture crystalline layer of TBA and TBHP contains, based on 100% of the total mass thereof, TBA 93 to 98.1%, TBHP1.5 to 6%, and impurities 0.018 to 0.045%, the impurity composition including TBF 0.01 to 0.025%, DTBP 0.008 to 0.02%.
13. The process according to claim 1, wherein in step 3) the recovered peroxide TBHP comprises, based on 100% of its total mass, 60 to 82% TBHP, 15 to 40% TBA, 0.5 to 0.85% impurities, said impurity composition comprising 0.25 to 0.4% TBF, 0.25 to 0.45% DTBP.
14. The process according to claim 1, wherein in step 4) the byproduct TBA purity is above 99.9wt% and the peroxide TBHP content is reduced to below 600 ppm.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108440246A (en) * 2018-02-23 2018-08-24 中山大学惠州研究院 A kind of separation method of the tert-butyl alcohol
CN110746276A (en) * 2019-12-05 2020-02-04 万华化学集团股份有限公司 Method for producing o-tert-butylphenol and p-tert-butylphenol by rectification and crystallization

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108440246A (en) * 2018-02-23 2018-08-24 中山大学惠州研究院 A kind of separation method of the tert-butyl alcohol
CN110746276A (en) * 2019-12-05 2020-02-04 万华化学集团股份有限公司 Method for producing o-tert-butylphenol and p-tert-butylphenol by rectification and crystallization

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