CN116023348A - Separation method and separation system for crude propylene oxide - Google Patents

Separation method and separation system for crude propylene oxide Download PDF

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Publication number
CN116023348A
CN116023348A CN202111244272.2A CN202111244272A CN116023348A CN 116023348 A CN116023348 A CN 116023348A CN 202111244272 A CN202111244272 A CN 202111244272A CN 116023348 A CN116023348 A CN 116023348A
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China
Prior art keywords
separation
tower
separation column
column
propylene oxide
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李木金
赵鹏
杨卫胜
施德磐
胡松
高瑞
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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Priority to CN202111244272.2A priority Critical patent/CN116023348A/en
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Abstract

The invention discloses a separation method and a separation system of crude epoxypropane, wherein the crude epoxypropane contains epoxypropane, hydrocarbons, oxygen-containing compounds and high-boiling-point substances, and the separation method comprises the following steps: the crude propylene oxide is introduced into a separation column I, and the concentration of the oxygen-containing compound on a tower plate in the separation column I is reduced by a mode of side-stream material of the separation column I. The concentration of the oxygen-containing compound enriched in the tower is reduced through side extraction, the concentration of the oxygen-containing compound enriched in the crude epoxypropane tower is controlled at a lower level, the problems of blockage, equipment corrosion caused by aldehyde polymerization and the like are avoided, the method is suitable for the production process for preparing epoxypropane by the reaction of propylene and peroxide, and a better technical effect can be achieved.

Description

Separation method and separation system for crude propylene oxide
Technical Field
The invention belongs to a separation method of crude epoxypropane, and particularly relates to a separation method and a separation system of crude epoxypropane.
Background
Propylene Oxide (PO) is a third large propylene derivative except polypropylene and acrylonitrile, is an important basic organic chemical synthetic raw material, and is mainly used for producing polyether, propylene glycol and the like. It is also the main raw material of fourth generation detergent nonionic surfactant, oil field demulsifier and pesticide emulsifier. Propylene oxide derivatives are widely used in the industries of automobiles, buildings, foods, tobacco, medicines, cosmetics and the like. The produced downstream products are nearly hundreds of kinds, and are important raw materials of fine chemical products.
The method for preparing propylene oxide (CHPPO) by epoxidation of propylene by cumene hydroperoxide has the advantages of low investment, environmental protection, no co-production and the like, is more and more paid attention to and researched, and is expected to replace the chlorohydrin method with high three wastes and serious corrosion.
CN1307168C discloses a method for purifying propylene oxide, which comprises subjecting a reaction solution obtained by reacting cumene hydroperoxide with propylene in an extractive distillation column with a hydrocarbon extractant having 7 to 20 carbon atoms, wherein the reaction solution contains propylene oxide and impurities such as water, hydrocarbons and oxygen-containing organic compounds, and the like, to extractive distillation, and is characterized in that the concentration of propylene glycol in the extractant fed to the extractive distillation column is 20 wt% or less.
Based on the above invention, further research shows that by-products such as aldehydes, alcohols, organic acids, water and other oxygen-containing compounds have boiling points between PO and heavier hydrocarbons such as ethylbenzene/isopropylbenzene/1, 2-propylene glycol, when the reaction products enter a rectifying tower together to separate crude propylene oxide, the oxygen-containing compounds are easy to be concentrated at local positions in the tower, and when the concentration reaches a certain degree, corrosion, blockage caused by aldehyde polymerization and other adverse conditions seriously affecting the stable operation of the device occur.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention provides a separation method and a separation system for crude propylene oxide, wherein the concentration of oxygen-containing compounds enriched in a tower is reduced through side extraction, the concentration of oxygen-containing compounds enriched in the crude propylene oxide tower is controlled at a lower level, the problems of blockage, organic acid corrosion equipment and the like caused by aldehyde polymerization are avoided, and the separation method and the separation system are suitable for the production process for preparing propylene oxide by the reaction of propylene and peroxide, and can achieve better technical effects.
An object of the present invention is to provide a separation method of crude propylene oxide containing propylene oxide, hydrocarbons, oxygen-containing compounds and high boiling point substances, comprising: the crude propylene oxide is introduced into a separation column I, and the concentration of the oxygen-containing compound on a tower plate in the separation column I is reduced by a mode of side-stream material of the separation column I.
Wherein, the high boiling point material refers to a material with a boiling point higher than 160 ℃.
In a preferred embodiment, the oxygen-containing compound comprises any one or any several of aldehyde, ketone, organic acid, alcohol, ester and water; and/or, the high boiling point material comprises cumene and/or dipropylene glycol; and/or the hydrocarbon comprises one or more than two of cumene, alpha-dimethylbenzyl alcohol and 1, 2-propylene glycol.
In a further preferred embodiment, the aldehyde is any one or any several of formaldehyde, acetaldehyde and propionaldehyde; and/or, the ketone is acetone; and/or the organic acid is any one or more of formic acid, acetic acid, propionic acid and benzoic acid; and/or the alcohol is methanol and/or ethanol; and/or the ester is methyl formate.
In a preferred embodiment, the crude propylene oxide has a propylene oxide concentration of 5 to 55% by mass, a hydrocarbon concentration of 0 to 90% (preferably excluding 0), an oxygen-containing compound concentration of 0 to 20% (preferably excluding 0), and a high boiling point material concentration of 0 to 10% (preferably excluding 0).
In a further preferred embodiment, the crude propylene oxide has a propylene oxide concentration of 5 to 50% by mass, a hydrocarbon concentration of 10 to 85% by mass, an oxygen-containing compound concentration of 0 to 15% (preferably excluding 0), and a high boiling point material concentration of 0 to 8% (preferably excluding 0).
For example, in the crude propylene oxide, the concentration of propylene oxide is 5%, 10%, 20%, 30%, 40% or 50%, the concentration of hydrocarbons is 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80%, the concentration of oxygen-containing compounds is 1%, 2%, 5%, 8%, 10%, 12% or 15%, and the concentration of high boiling point substances is 1%, 2%, 3%, 4%, 5%, 6%, 7% or 8% in terms of mass concentration.
In a preferred embodiment, the crude propylene oxide is introduced into the separation column I, the light component I is withdrawn at the upper part or top of the separation column I, the heavy component I is withdrawn at the lower part or bottom of the separation column, and the material containing the oxygen-containing compound is withdrawn at the side stream of the separation column I.
In a further preferred embodiment, propylene oxide and optionally an oxygenate are included in the light component I; and/or the heavy component I comprises hydrocarbons, high boiling point substances and (small amount of) propylene oxide; and/or, the side offtake material comprises an oxygenate and propylene oxide.
In a still further preferred embodiment, in the light component I, the concentration of propylene oxide is 95% to 99% and the concentration of the oxygen-containing compound is 1% to 5% by mass; and/or, in the heavy component I, the concentration of propylene oxide is 0-2%, and the total concentration of hydrocarbons and high boiling point substances is 98-100%; in the side offtake material, the concentration of epoxypropane is 97% -99.5%, and the concentration of oxygen-containing compound is 0.5% -3%.
For example, in the light component I, the concentration of propylene oxide is 95%, 96%, 97%, 98% or 99% and the concentration of the oxygen-containing compound is 1%, 2%, 3%, 4% or 5% by mass concentration; and/or, in the heavy component I, the concentration of propylene oxide is 0%, 0.5%, 1%, 1.5% or 2%; in the side offtake, the concentration of propylene oxide was 97%, 97.5%, 98%, 98.5%, 99% or 99.5%, and the concentration of oxygenates was 0.5%, 1%, 1.5%, 2%, 2.5% or 3%.
In a preferred embodiment, the side offtake of the separation column I is fed to the separation column II.
In a further preferred embodiment, the light fraction II is withdrawn from the upper part or top of the separation column II, the heavy fraction II is withdrawn from the lower part or bottom of the separation column II and (the heavy fraction II) is recycled back to the separation column I.
The side recovery circulation is a combination, the material flow with high concentration of the oxygen-containing compound is subjected to side recovery treatment, the material flow with low concentration of the oxygen-containing compound is obtained to return, and if the material flow is not circulated, the purpose of reducing the concentration of the oxygen-containing compound on the tower plate of the separation tower I cannot be realized.
In a further preferred embodiment, the concentration of propylene oxide in the light component II is 96-99% and the concentration of the oxygen-containing compound is 1-4% by mass concentration; and/or in the heavy component II, the concentration of the epoxy compound is 98-99.9%, and the concentration of the oxygen-containing compound is 0.1-2%.
For example, in the light component II, the concentration of propylene oxide is 96%, 97%, 98% or 99% and the concentration of the oxygen-containing compound is 1%, 2%, 3% or 4% in terms of mass concentration; and/or in the heavy component II, the concentration of the epoxy compound is 98%, 98.5%, 99%, 99.5% or 99.9%, and the concentration of the oxygen-containing compound is 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8% or 2%.
In the invention, the light component I led out from the top or upper part of the separation tower I is the target product I, and the light component II led out from the top or upper part of the separation tower II is the target product II. Meanwhile, the heavy component II with higher propylene oxide concentration is recycled to the separation tower I, so that the concentration of the oxygen-containing compound in the separation tower I can be further diluted.
In a preferred embodiment, the process is carried out in separation column I and separation column II, the crude propylene oxide being introduced into separation column I: light component I is extracted from the upper part or the top of the separation tower I, heavy component I is extracted from the lower part or the bottom of the separation tower I, and side line extraction materials enter the separation tower II; in the separation column II: light fraction II is withdrawn from the upper or top part thereof, heavy fraction II is withdrawn from the lower or bottom part thereof, and the heavy fraction II is recycled back to the separation column I.
In a preferred embodiment, the weight ratio of side offtake to crude propylene oxide in the feed to the separation column I is from 1:1000 to 1:50, preferably from 1:500 to 1:100.
For example, the weight ratio of side offtake to crude propylene oxide in the feed to separation column I is 1:1000, 1:800, 1:600, 1:500, 1:400, 1:300, 1:200, 1:100, 1:80, or 1:50.
Wherein if the production amount is higher than 1:50, the load on the separation column II is excessively high and the oxygenate concentration of the separation column I is not always lowered.
In a preferred embodiment, the side offtake position of the separation column I is higher than the feed position of the separation column I (i.e. the feed position of the crude propylene oxide).
The concentration of the oxygen-containing compound below the feeding position of the separation tower I is lower, and the purpose of removing the oxygen-containing compound cannot be achieved by side-line extraction, so that the side-line extraction position is required to be higher than the feeding position, and the separation tower I is preferably extracted from a tower plate with low concentration of cumene.
In a further preferred embodiment, the theoretical plate number between the feed position and the side offtake position of the separation column I amounts to 10 to 80%, preferably 20 to 70%, of the total theoretical plate number of the separation column I.
For example, the theoretical plate number between the feed position and the side offtake position of the separation column I is 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80% of the total theoretical plate number of the separation column I.
In a preferred embodiment, the location at which heavy components II of separation column II are recycled back to separation column I is between the feed location and the side offtake location of separation column I.
Wherein, since the recycle stream is a heavy component relative to the sidedraw stream, it should be recycled back to the separation column I below the sidedraw location; whereas if the recycle position is located below the feed position this will result in too high an amount of propylene oxide in the heavy fraction I at the bottom or lower part of the separation column I.
In a preferred embodiment, the side offtake of the separation column I enters the separation column II from the upper, middle or top part of the separation column II.
Preferably, when the top of the separation tower II is provided with a condenser, side offtake materials of the separation tower I enter the separation tower II from the upper part, the middle part or the top of the separation tower II; when the top of the separation tower II is not provided with a condenser, side offtake materials of the separation tower I enter the separation tower II from the upper part or the top of the separation tower II.
In a further preferred embodiment, the side offtake from the separation column I enters the separation column II from 0 to 30% of the trays of the separation column II, for example from the first tray, in a number of trays of the separation column II from top to bottom of 0 to 100%.
In the invention, a material flow containing oxygen-containing compounds such as propylene oxide, ester, aldehyde, water, organic acid and the like is extracted from a separation tower I through a side line to be removed from the separation tower II, partial vaporization of the oxygen-containing compounds is carried out in the separation tower II, the oxygen-containing compounds are extracted from the upper part or the top of the separation tower II to be outside the boundary by utilizing the difference of the volatility of the oxygen-containing compounds and the volatility of the propylene oxide, and the purer propylene oxide is obtained at the lower part or the tower bottom of the separation tower I and is returned to the separation tower I, so that the concentration of the oxygen-containing compounds on a tower plate of the separation tower I can be further diluted, and the purpose of reducing the concentration of the oxygen-containing compounds on a first separation tower plate is realized. It should be noted that, taking the CHPPO method as an example, the concentration of the oxygenate below the feeding position is low in the separation column I, and the purpose of removing the oxygenate cannot be achieved in the side-draw, so that the side-draw position needs to be higher than the feeding position, and the side-draw position is preferably from the tray where the concentration of cumene is low.
In a preferred embodiment, the theoretical plate number of the separation column I is 10-95, the column top operation pressure is 0.00-0.1 MPaG, the column top operation temperature is 20-80 ℃, the column bottom operation temperature is 120-210 ℃, and the reflux ratio is 0.1-10.
In a further preferred embodiment, the theoretical plate number of the separation column I is 10-90, the column top operation pressure is 0-0.08 MPaG, the column top operation temperature is 20-70 ℃, the column bottom operation temperature is 120-200 ℃, and the reflux ratio is 1-5.
For example, the theoretical plate number of the separation column I is 10, 20, 30, 40, 50, 60, 70, 80 or 90, the column top operation pressure is 0MPaG, 0.01MPaG, 0.02MPaG, 0.03MPaG, 0.04MPaG, 0.05MPaG, 0.06MPaG, 0.07MPaG or 0.08MPaG, the column top operation temperature is 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃ or 70 ℃, the column bottom operation temperature is 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃ or 200 ℃, and the reflux ratio is 1,2, 3, 4 or 5.
In a preferred embodiment, the theoretical plate number of the separation column II is 5-50, the column top operation pressure is 0.00-0.1 MPaG, the column top operation temperature is 30-70 ℃, and the column bottom operation temperature is 30-90 ℃.
In a further preferred embodiment, the theoretical plate number of the separation column II is 5-40, the column top operation pressure is 0.00-0.08 MPaG, the column top operation temperature is 30-65 ℃, and the column bottom operation temperature is 30-80 ℃.
For example, the theoretical plate number of the separation column II is 5, 10, 15, 20, 25, 30, 35 or 40, the column top operation pressure is 0MPaG, 0.01MPaG, 0.02MPaG, 0.03MPaG, 0.04MPaG, 0.05MPaG, 0.06MPaG, 0.07MPaG or 0.08MPaG, the column top operation temperature is 30 ℃, 40 ℃, 50 ℃, 60 ℃ or 65 ℃, and the column bottom operation temperature is 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃ or 80 ℃.
In a still further preferred embodiment, the difference between the top temperature of the separation column II and the bottom temperature is between 0.1 and 6℃and preferably between 0.2 and 3 ℃.
For example, the difference between the temperature at the top and the temperature at the bottom of the separation column II is 0.1 ℃, 0.2 ℃, 0.5 ℃, 1 ℃,2 ℃,3 ℃,4 ℃,5 ℃ or 6 ℃.
In the above technical solution, the separation column II may be provided with no condenser and no reflux drum, and the overhead gas is directly led out, but provided with a reboiler.
Therefore, the invention controls the concentration of the oxygen-containing compound in the crude epoxypropane tower at a lower level, avoids the problems of blockage and equipment corrosion caused by aldehyde polymerization, is suitable for the production process of preparing epoxypropane by the reaction of propylene and peroxide, and can obtain better technical effect.
It is a second object of the present invention to provide a separation system for crude propylene oxide, preferably for carrying out the separation method according to one of the objects of the present invention, wherein the separation system comprises a separation column I on which a feed port I and a side offtake are provided, and a separation column II on which a feed port II is provided, the side offtake being connected to the feed port II by a pipeline.
In a preferred embodiment, a light component outlet I and a heavy component outlet I are further provided on the separation column I.
In a further preferred embodiment, the light fraction outlet I is provided in the upper part or top of the separation column I and the heavy fraction outlet I is provided in the lower part or bottom of the separation column I.
In a preferred embodiment, the feed inlet I is provided in a middle lower portion of the separation column I, and the side draw outlet is provided above the feed inlet I.
In a further preferred embodiment, the theoretical plate number between the feed inlet I and the side offtake of the separation column I is from 10 to 80%, preferably from 20 to 70%, of the total theoretical plate number of the separation column I.
In a preferred embodiment, the side offtake is arranged below the light component outlet I.
In a preferred embodiment, the feed inlet I is arranged above the heavy fraction outlet I.
In a preferred embodiment, a light component outlet II and a heavy component outlet II are further provided on the separation column II.
In a further preferred embodiment, a light fraction outlet II is provided in the upper part or top of the separation column II and a heavy fraction outlet II is provided in the lower part or bottom of the separation column II.
In a preferred embodiment, a recycle inlet is provided on the separation column I.
In a further preferred embodiment, the recycle inlet is connected via a line to the heavy ends outlet II of the separation column II.
In a still further preferred embodiment, on the separation column I, the recycle inlet is arranged between the feed inlet I and the side offtake.
In a preferred embodiment, the separation column II may be equipped without a condenser and reflux drum, with the overhead gas being directly withdrawn, but with a reboiler.
In a preferred embodiment, the theoretical plate number of the separation column I is 10-95, the column top operation pressure is 0.00-0.1 MPaG, the column top operation temperature is 20-80 ℃, the column bottom operation temperature is 120-210 ℃, and the reflux ratio is 0.1-10.
In a further preferred embodiment, the theoretical plate number of the separation column I is 10-90, the column top operation pressure is 0-0.08 MPaG, the column top operation temperature is 20-70 ℃, the column bottom operation temperature is 120-200 ℃, and the reflux ratio is 1-5.
For example, the theoretical plate number of the separation column I is 10, 20, 30, 40, 50, 60, 70, 80 or 90, the column top operation pressure is 0MPaG, 0.01MPaG, 0.02MPaG, 0.03MPaG, 0.04MPaG, 0.05MPaG, 0.06MPaG, 0.07MPaG or 0.08MPaG, the column top operation temperature is 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃ or 70 ℃, the column bottom operation temperature is 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃ or 200 ℃, and the reflux ratio is 1,2, 3, 4 or 5.
In a preferred embodiment, the theoretical plate number of the separation column II is 5-50, the column top operation pressure is 0.00-0.1 MPaG, the column top operation temperature is 30-70 ℃, and the column bottom operation temperature is 30-90 ℃.
In a further preferred embodiment, the theoretical plate number of the separation column II is 5-40, the column top operation pressure is 0.00-0.08 MPaG, the column top operation temperature is 30-65 ℃, and the column bottom operation temperature is 30-80 ℃.
For example, the theoretical plate number of the separation column II is 5, 10, 15, 20, 25, 30, 35 or 40, the column top operation pressure is 0MPaG, 0.01MPaG, 0.02MPaG, 0.03MPaG, 0.04MPaG, 0.05MPaG, 0.06MPaG, 0.07MPaG or 0.08MPaG, the column top operation temperature is 30 ℃, 40 ℃, 50 ℃, 60 ℃ or 65 ℃, and the column bottom operation temperature is 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃ or 80 ℃.
In a still further preferred embodiment, the difference between the top temperature and the bottom temperature of the separation column II is between 0.1 and 6 ℃, preferably between 0.2 and 3 ℃.
The endpoints of the ranges and any values disclosed in the present invention are not limited to the precise range or value, and the range or value should be understood to include values close to the range or value. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. In the following, the individual technical solutions can in principle be combined with one another to give new technical solutions, which should also be regarded as specifically disclosed herein.
Compared with the prior art, the invention has the following beneficial effects: the method controls the concentration of the oxygen-containing compound in the crude epoxypropane tower to be lower, avoids the problems of blockage, equipment corrosion caused by aldehyde polymerization and the like, is suitable for the production process for preparing epoxypropane by the reaction of propylene and peroxide, and can obtain better technical effect.
Drawings
Figure 1 shows a schematic view of a separation system according to the invention.
1-crude propylene oxide, 2-light component I, 3-heavy component I, 4-side offtake material, 5-light component II and 6-heavy component II;
the reaction product of the epoxidation reaction of the peroxide and the propylene and the removal of the propylene mainly comprises epoxypropane, hydrocarbons, aldehydes, esters, water, organic acid and other oxygen-containing compounds, and the high-boiling point substance is crude epoxypropane 1;
the crude epoxypropane 1 enters a separation tower I, a light component I2 mainly containing epoxypropane is obtained at the tower top, a heavy component I3 containing hydrocarbons, high boiling point substances and a small amount of epoxypropane is obtained at the tower bottom, and a side-stream extraction material 4 containing epoxypropane and oxygen-containing compounds (including aldehydes, esters, water, organic acids and the like) is extracted from the side stream;
the side offtake material 4 enters a separation tower II, and a light component II 5 mainly comprising propylene oxide and oxygen-containing compounds (including aldehydes, esters, water and the like) is obtained at the top of the separation tower; and returning the heavy component II 6 containing propylene oxide obtained from the tower bottom to the separation tower I.
The separation tower I is provided with a reboiler, a condenser and an inlet and outlet material flow thereof, the separation tower II is provided with a reboiler and an inlet and outlet material flow thereof, the separation tower II can be directly led out without the condenser and a reflux tank, and the flow and the function of the separation tower I are easily understood by a person skilled in the art and are not repeated.
Fig. 2 shows a schematic diagram of a comparative example.
In FIG. 2, 7-fresh feed, I-separation column I.
When the method shown in fig. 2 is adopted:
the reaction product containing propylene oxide enters a separation tower I, the reaction product mainly comprises propylene oxide, hydrocarbon, oxygen-containing compounds and high boiling point substances, a crude propylene oxide product is extracted from the tower top, and a material flow containing hydrocarbon, high boiling point substances and a small amount of propylene oxide is extracted from the tower bottom.
Detailed Description
The present invention is described in detail below with reference to specific embodiments, and it should be noted that the following embodiments are only for further description of the present invention and should not be construed as limiting the scope of the present invention, and some insubstantial modifications and adjustments of the present invention by those skilled in the art from the present disclosure are still within the scope of the present invention.
In addition, the specific features described in the following embodiments may be combined in any suitable manner without contradiction. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention can be made, so long as the concept of the present invention is not deviated, and the technical solution formed thereby is a part of the original disclosure of the present specification, and also falls within the protection scope of the present invention.
The raw materials used in examples and comparative examples, if not particularly limited, are all as disclosed in the prior art, and are, for example, available directly or prepared according to the preparation methods disclosed in the prior art.
[ example 1 ]
As shown in FIG. 1, the reaction products containing 0.1% of acetaldehyde, 0.1% of methyl formate, 14% of propylene oxide, 0.2% of water, 0.01% of formic acid, 1, 2-propanediol 1%, cumene 48.49%, 33.1% of alpha, alpha-dimethylbenzyl alcohol, 1% of cumene and 2% of other components by weight are fed into 30 th plate of a separation column I, 40 th plates of the separation column I are total (1-40 th plates from the top to the bottom of the column), the operating pressure of the top of the column is 0.04MPaG, the operating temperature of the top of the column is 44 ℃, the operating temperature of the bottom of the column is 181 ℃, and the reflux ratio is 2.
On the separation column I, the light component I contains 97.22 percent of propylene oxide and 2.78 percent of oxygen-containing compound; the side-mining material contains 98.12 percent of propylene oxide and 1.88 percent of oxygen-containing compound; the heavy component I contains 0.02% of propylene oxide and 99.97% of (hydrocarbon + high boilers) and 0.01% of oxygen-containing compounds.
On the separation column II, 97.82% propylene oxide was contained in the light fraction II; the recycle contained 98.12% propylene oxide and 1.88% oxygenates.
The product of which the mass flow rate is 1% of that of the raw material extracted from the side line of the 10 th tower plate of the separation tower I is removed from the first plate of the separation tower II, the total of 10 plates of the separation tower II is treated, the operation pressure of the tower top is 0.04MPaG, the operation temperature of the tower top is 44 ℃, the operation temperature of the tower bottom is 45 ℃, and the liquid phase extracted from the tower bottom returns to the 11 th plate of the separation tower I.
The highest concentration of the oxygen-containing compound in the separation tower I is 0.6958 percent of acetaldehyde, 0.6954 percent of methyl formate, 1.3912 percent of water and 0.0533 percent of formic acid.
[ example 2 ]
The procedure of example 1 was repeated, except that the product taken from the side stream of the separation column I was 0.5% of the mass flow of the raw material.
On the separation column I, 97.14% propylene oxide is contained in the light component I; the side-mining material contains 98.05 percent of propylene oxide and 1.95 percent of oxygen-containing compound; the heavy component I contains 0.56% of propylene oxide and 99.42% of (hydrocarbon + high boilers) and 0.02% of oxygenates.
On separation column II, light fraction II contained 97.75% propylene oxide and 2.25% oxygenates; the recycle contained 98.06% propylene oxide and 1.94% oxygenates.
The highest concentration of the oxygen-containing compound in the separation tower I is 0.7176% of acetaldehyde, 0.7102% of methyl formate, 1.4369% of water and 0.0448% of formic acid.
[ example 3 ]
The procedure of example 1 was repeated, except that the product from the side draw of the 7 th tray of the separation column I was removed from the first plate of the separation column II, and the column II bottoms liquid phase was returned to the 8 th plate of the separation column I.
On the separation column I, the light component I contains 97.22 percent of propylene oxide and 2.78 percent of oxygen-containing compound; the side-mining material contains 98.09 percent of propylene oxide and 0.0191 percent of oxygen-containing compound; the heavy component I contains 0.03% of propylene oxide and 99.97% of (hydrocarbon + high boilers).
On the separation column II, the light component II contains 97.79 percent of propylene oxide and 2.21 percent of oxygen-containing compound; the recycle contained 98.10% propylene oxide and 1.90% oxygenates.
The highest concentration of the oxygen-containing compound in the separation tower I is 0.6958 percent of acetaldehyde, 0.6954 percent of methyl formate, 1.3912 percent of water and 0.0530 percent of formic acid.
[ example 4 ]
The procedure of example 1 was repeated, except that the column top operation pressure of the separation column I was 0MPaG, the column top operation temperature was 35℃and the column bottom operation temperature was 167 ℃. The separation column II was operated at a column top pressure of 0MPaG, a column top operating temperature of 34℃and a column bottom operating temperature of 35 ℃.
On the separation column I, the light component I contains 97.22 percent of propylene oxide and 2.78 percent of oxygen-containing compound; the side-mining material contains 98.05 percent of propylene oxide and 1.95 percent of oxygen-containing compound; the heavy component I contains 0.03% of propylene oxide and 99.97% of (hydrocarbon + high boilers).
On the separation column II, 97.77% propylene oxide is contained in the light component II; the circulating material contains 98.06 percent of propylene oxide and 1.94 percent of oxygen-containing compound; .
The highest concentration of the oxygen-containing compound in the separation tower I is 0.6959 percent of acetaldehyde, 0.6954 percent of methyl formate, 1.3912 percent of water and 0.0529 percent of formic acid.
[ example 5 ]
The procedure of example 1 was repeated, except that the separation column I was operated at a column top pressure of 0.1MPaG, a column top operation temperature of 55℃and a column bottom operation temperature of 196 ℃. The separation column II was operated at a column top pressure of 0.1MPaG, a column top operating temperature of 55℃and a column bottom operating temperature of 56 ℃.
On the separation column I, the light component I contains 97.22 percent of propylene oxide and 2.78 percent of oxygen-containing compound; the side-mining material contains 98.17 percent of propylene oxide and 1.83 percent of oxygen-containing compound; the heavy component I contains 0.02% of propylene oxide and 99.97% of (hydrocarbon + high boilers) and 0.01% of oxygen-containing compounds.
On the separation column II, the light component II contains 97.85 percent of propylene oxide and 2.15 percent of oxygen-containing compound; the recycle contained 98.18% propylene oxide and 1.82% oxygenates.
The highest concentration of the oxygen-containing compound in the separation tower I is 0.6958 percent of acetaldehyde, 0.6954 percent of methyl formate, 1.3912 percent of water and 0.0647 percent of formic acid.
[ example 6 ]
As shown in FIG. 1, the reaction products containing 0.1% of acetaldehyde, 0.1% of methyl formate, 14% of propylene oxide, 0.2% of water, 0.01% of formic acid, 1, 2-propanediol 1%, cumene 48.49%, 33.1% of alpha, alpha-dimethylbenzyl alcohol, 1% of cumene and 2% of other components by weight are fed into 60 th plates of a separation column I, 80 th plates of the separation column I are total (1-80 th plates from the top to the bottom of the column), the operating pressure of the top is 0.04MPaG, the operating temperature of the top is 44 ℃, the operating temperature of the bottom of the column is 181 ℃, and the reflux ratio is 2.
On the separation column I, the light component I contains 97.22 percent of propylene oxide and 2.78 percent of oxygen-containing compound; the side-mining material contains 98.13 percent of propylene oxide and 1.87 percent of oxygen-containing compound; the heavy component I contains 0.02% of propylene oxide, 99.97% of (hydrocarbon + high boilers) and 0.01% of oxygen-containing compounds.
On separation column II, light fraction II contained 97.82% propylene oxide and 2.18% oxygenates; the recycle contained 98.13% propylene oxide and 1.87% oxygenates.
The product of which the mass flow rate is 1% of that of the raw material extracted from the side line of the 20 th tower plate of the separation tower I is removed from the first plate of the separation tower II, the total of 20 plates of the separation tower II is subjected to tower top operation pressure of 0.04MPaG, the tower top operation temperature is 44 ℃, the tower bottom operation temperature is 45 ℃, and the liquid phase extracted from the tower bottom is returned to the 22 nd plate of the separation tower I.
The highest concentration of the oxygen-containing compound in the separation tower I is 0.6959 percent of acetaldehyde, 0.6956 percent of methyl formate, 1.3912 percent of water and 0.0535 percent of formic acid.
In the present invention, the light component I component content is the same in some examples, because the influence of the change in conditions on the overhead material is relatively small.
Comparative example 1
As shown in FIG. 2, the reaction product containing 0.1% of acetaldehyde, 0.1% of methyl formate, 14% of propylene oxide, 0.2% of water, 0.01% of formic acid, 1, 2-propanediol 1%, cumene 48.49%, 33.1% of alpha, alpha-dimethylbenzyl alcohol, 1% of cumene and 2% of other components by weight was fed into the 30 th plate of a separation column I, 40 th plates of the separation column I in total, the operation pressure at the top of the column was 0.04MPaG, the operation temperature at the top of the column was 44 ℃, the operation temperature at the bottom of the column was 167 ℃ and the reflux ratio was 2.
The highest concentration of the oxygen-containing compound in the separation tower I is 0.7395 percent of acetaldehyde, 0.7212 percent of methyl formate, 1.4860 percent of water and 0.0453 percent of formic acid.
It can be seen that the higher concentration of oxygenates on the trays in this example than in the examples, the polymerization of aldehydes may lead to plugging, and although the organic acid content is somewhat lower than in the examples, the higher water content in this example results in more corrosive and may be detrimental to the industrial process.
The invention has been described in detail in connection with the specific embodiments and exemplary examples thereof, but such description is not to be construed as limiting the invention. It will be understood by those skilled in the art that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, and these fall within the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims (14)

1. A method for separating crude propylene oxide, wherein the crude propylene oxide contains propylene oxide, hydrocarbons, oxygenates and high boiling point materials, the method comprising: the crude propylene oxide is introduced into a separation column I, and the concentration of the oxygen-containing compound on a tower plate in the separation column I is reduced by a mode of side-stream material of the separation column I.
2. The separation method according to claim 1, wherein,
in the crude propylene oxide, the concentration of the propylene oxide is 5 to 55 percent, preferably 5 to 50 percent, in terms of mass concentration; and/or the concentration of hydrocarbons is 0 to 90%, preferably 10 to 85%; and/or the concentration of the oxygen-containing compound is 0 to 20%, preferably 0 to 15%; and/or the concentration of the high boiling point substance is 0 to 10%, preferably 0 to 8%;
preferably: the oxygen-containing compound comprises any one or more of aldehyde, ketone, organic acid, alcohol, ester and water; and/or, the high boiling point material comprises cumene and/or dipropylene glycol; and/or the hydrocarbon comprises one or more than two of cumene, alpha-dimethylbenzyl alcohol and 1, 2-propylene glycol.
3. The separation method according to claim 1, wherein the crude propylene oxide is introduced into the separation column I, a light component I is introduced into the upper part or the top of the separation column I, a heavy component I is introduced into the lower part or the bottom of the separation column, and a material containing an oxygen-containing compound is introduced into the side stream of the separation column I.
4. The separation method according to claim 1, wherein the material extracted from the side line of the separation column I enters the separation column II; preferably, the light component II is led out from the upper part or the top of the separation column II, the heavy component II is led out from the lower part or the bottom of the separation column II, and the heavy component II is recycled to the separation column I.
5. The separation process according to claim 1, wherein the process is carried out in separation column I and separation column II, the crude propylene oxide being introduced into separation column I: light component I is extracted from the upper part or the top of the separation tower I, heavy component I is extracted from the lower part or the bottom of the separation tower I, and side line extraction materials enter the separation tower II; in the separation column II: light fraction II is withdrawn from the upper or top part thereof, heavy fraction II is withdrawn from the lower or bottom part thereof, and the heavy fraction II is recycled back to the separation column I.
6. The separation method according to claim 1, characterized in that the weight ratio of side offtake material of the separation column I to crude propylene oxide in the feed is 1:1000 to 1:50, preferably 1:500 to 1:100.
7. The separation method according to claim 4, wherein,
the theoretical plate number between the feeding position and the side-draw position of the separation column I is 10 to 80%, preferably 20 to 70% of the total theoretical plate number of the separation column I; and/or the number of the groups of groups,
the location at which the heavy fraction II of the separation column II is recycled back to the separation column I is between the feed location and the side offtake location of the separation column I.
8. The separation method according to claim 1, wherein the side offtake of the separation column I enters the separation column II from the upper part, the middle part or the top of the separation column II; preferably, the side offtake material of the separation tower I enters the separation tower II from 0 to 30 percent of the tower plates of the separation tower II according to the tower plate number of the separation tower II from top to bottom.
9. A separation process according to claim 1 to 8, wherein,
the theoretical plate number of the separation tower I is 10-95, the tower top operation pressure is 0.00-0.1 MPaG, the tower top operation temperature is 20-80 ℃, the tower kettle operation temperature is 120-210 ℃, and the reflux ratio is 0.1-10; and/or the number of the groups of groups,
the theoretical plate number of the separation tower II is 5-50, the tower top operation pressure is 0.00-0.1 MPaG, the tower top operation temperature is 30-70 ℃, and the tower bottom operation temperature is 30-90 ℃.
10. The separation process according to claim 9, characterized in that the difference between the top temperature and the bottom temperature of the separation column II is between 0.1 and 6 ℃, preferably between 0.2 and 3 ℃.
11. A separation system for crude propylene oxide, preferably for carrying out the separation process according to one of claims 1 to 10, wherein the separation system comprises a separation column I on which a feed inlet I and a side offtake are arranged and a separation column II on which a feed inlet II is arranged, the side offtake being connected to the feed inlet II by a pipeline.
12. The separation system of claim 11, wherein the separation system comprises a plurality of separation devices,
the separation tower I is further provided with a light component outlet I and a heavy component outlet I; preferably, the light component outlet I is arranged at the upper part or the top of the separation tower I, and the heavy component outlet I is arranged at the lower part or the bottom of the separation tower I; and/or the number of the groups of groups,
the middle lower part of the separation tower I is provided with the feed inlet I, and the side line extraction outlet is arranged above the feed inlet I; preferably, the theoretical plate number between the feed inlet I and the side offtake of the separation column I is from 10 to 80%, preferably from 20 to 70%, of the total theoretical plate number of the separation column I.
13. The separation system of claim 11, wherein the separation system comprises a plurality of separation devices,
the side-draw outlet is arranged below the light component outlet I; and/or the number of the groups of groups,
the feed inlet I is arranged above the heavy component outlet I; and/or the number of the groups of groups,
the separation tower II is further provided with a light component outlet II and a heavy component outlet II; preferably, a light component outlet II is arranged at the upper part or the top of the separation tower II, and a heavy component outlet II is arranged at the lower part or the bottom of the separation tower II; and/or the number of the groups of groups,
a circulating material inlet is arranged on the separation tower I; preferably, the circulating material inlet is connected with the heavy component outlet II of the separation tower II through a pipeline; more preferably, on the separation column I, the recycle inlet is disposed between the feed inlet I and the side offtake.
14. A separation system as claimed in any one of claims 11 to 13, characterized in that,
the theoretical plate number of the separation tower I is 10-95, the tower top operation pressure is 0.00-0.1 MPaG, the tower top operation temperature is 20-80 ℃, the tower kettle operation temperature is 120-210 ℃, and the reflux ratio is 0.1-10; and/or the number of the groups of groups,
the theoretical plate number of the separation tower II is 5-50, the tower top operation pressure is 0.00-0.1 MPaG, the tower top operation temperature is 30-70 ℃, and the tower bottom operation temperature is 30-90 ℃; and/or the number of the groups of groups,
the difference between the top temperature and the bottom temperature of the separation column II is between 0.1 and 6 ℃, preferably between 0.2 and 3 ℃.
CN202111244272.2A 2021-10-26 2021-10-26 Separation method and separation system for crude propylene oxide Pending CN116023348A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2013148092A (en) * 2012-10-29 2015-05-10 Чайна Петролеум Энд Кемикал Корпорейшн METHOD FOR CLEANING PROPYLENE OXIDE
CN109851590A (en) * 2017-11-30 2019-06-07 中国石油化工股份有限公司 The purification process of propylene oxide
CN111205248A (en) * 2019-12-02 2020-05-29 万华化学集团股份有限公司 Deacidifying method in propylene oxide refining process
CN113429368A (en) * 2021-06-15 2021-09-24 万华化学集团股份有限公司 Method for removing impurities in epoxypropane separation process

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2013148092A (en) * 2012-10-29 2015-05-10 Чайна Петролеум Энд Кемикал Корпорейшн METHOD FOR CLEANING PROPYLENE OXIDE
CN109851590A (en) * 2017-11-30 2019-06-07 中国石油化工股份有限公司 The purification process of propylene oxide
CN111205248A (en) * 2019-12-02 2020-05-29 万华化学集团股份有限公司 Deacidifying method in propylene oxide refining process
CN113429368A (en) * 2021-06-15 2021-09-24 万华化学集团股份有限公司 Method for removing impurities in epoxypropane separation process

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