CN109851588B - Method for purifying propylene oxide - Google Patents
Method for purifying propylene oxide Download PDFInfo
- Publication number
- CN109851588B CN109851588B CN201810153538.4A CN201810153538A CN109851588B CN 109851588 B CN109851588 B CN 109851588B CN 201810153538 A CN201810153538 A CN 201810153538A CN 109851588 B CN109851588 B CN 109851588B
- Authority
- CN
- China
- Prior art keywords
- propylene glycol
- extractant
- monomethyl ether
- glycol monomethyl
- dimethyl ether
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Epoxy Compounds (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a method for refining propylene oxide, which mainly solves the problems of low purity of an extracting agent, high loss, low yield of propylene oxide and high energy consumption caused by the cyclic accumulation of heavy component impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether in the prior art. The method comprises the steps of separating a feed stream containing propylene oxide, an extractant, and propylene glycol monomethyl ether and propylene glycol dimethyl ether in a separation column; the separation column is operated under conditions sufficient for the extractant to form an azeotrope with propylene glycol monomethyl ether and propylene glycol dimethyl ether, and a stream containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope is taken off at the separation column side. The method can be used in the industrial production of propylene oxide.
Description
Technical Field
The invention relates to a refining method of propylene oxide, in particular to a purification method of an extracting agent recovered by a propylene oxide extractive distillation process.
Background
Propylene Oxide (PO) is mainly used for the production of polyether polyols, propylene glycol and propylene glycol ethers, the second largest propylene derivatives being produced next to polypropylene in propylene derivatives. It was counted that about 66% of the total consumption of propylene oxide, about 17% for propylene glycol production and about 6% for propylene glycol ether production was globally used for polyether polyol production in 2011. In 2011, the global propylene oxide production capacity is 882.2 ten thousand tons, and in 2016, 1000 ten thousand tons are broken through. By 2020, propylene oxide production capacity is expected to reach 1200 ten thousand tons/year and the demand reaches 1000 ten thousand tons/year. In the long term, the market prospect of propylene oxide is still optimistic worldwide.
The annual demand for propylene oxide is expected to increase by 4-8% in the coming years, wherein the demand for Asian markets may increase more rapidly, and especially in recent years, the consumption of propylene oxide in China and India markets is more rapidly increased than that in other countries. The annual demand of propylene oxide is expected to reach about 1300-1400 million tons in the five years in the future.
The major areas of world propylene oxide production are in western europe, north america and asia. The industry for foreign propylene oxide is highly concentrated and the U.S. Dow chemical and Lyondell company is the largest producer worldwide, controlling most of the world's propylene oxide market. Dow chemical company has built production facilities in the United states, Germany, Pasteur, etc. respectively, all adopting chlorohydrin process technology. Lyondell corporation has established production facilities in the United states, the French, the Netherlands, China, and the like, respectively, and adopts a co-oxidation process technology. At present, the yield of the propylene oxide produced by adopting a chlorohydrin method route in the world accounts for 40-45% of the total production capacity, and the yield produced by an oxidation method accounts for 55-60%. With the increasing environmental requirements, the chlorohydrin process is gradually replaced.
As a method for producing propylene oxide, a method of reacting cumene hydroperoxide (or ethylbenzene) with propylene is known. The reaction solution obtained by the reaction contains a purposeful reaction product of propylene oxide, and also contains C5-C6 hydrocarbons, water, aldehyde (acetaldehyde + propionaldehyde) and oxygen-containing organic compound impurities such as methanol, acetone, methyl formate and the like. Therefore, a plurality of purification steps for separating and recovering high-purity propylene oxide from the reaction solution are required.
The propylene oxide product has strict requirements on water and aldehyde, the water can influence the hydroxyl value and the foaming performance of the polymer, the content of the aldehyde is an environmental requirement, and C5-C6 hydrocarbons can influence the chromaticity of the product, so that the national standard has strict requirements on the purity of the product.
The quality and purity requirements of the high-class products of the propylene oxide in the national standard are as follows: more than or equal to 99.95 percent of propylene oxide, less than or equal to 0.02 percent of water, less than or equal to 0.005 percent of acetaldehyde and propionaldehyde, and less than or equal to 0.003 percent of acid.
The impurities such as water, methanol, acetone, methyl formate and the like contained in the crude propylene oxide generated by the reaction form an azeotrope with the propylene oxide or the relative volatility is close to 1, and the common rectification is difficult to reach the standards of the propylene oxide product. In order to obtain propylene oxide of high purity which meets the polymerization requirements, it is necessary to separate and remove impurities contained in the propylene oxide.
The purification of propylene oxide generally employs C7-C20 straight and branched chain hydrocarbons and/or glycols as extractants. For economic reasons, the purification of propylene oxide uses a mixture of linear and branched alkanes of C8 as extractant. The addition of the extractant increases the relative volatility of acetaldehyde, water, methanol and methyl formate to propylene oxide, and the acetaldehyde, water, methanol and methyl formate are removed from the top of the tower.
In the process of refining the propylene oxide, the existence of water inevitably causes the propylene oxide to be hydrolyzed to generate 1, 2-propylene glycol, the 1, 2-propylene glycol reacts with impurity methanol to generate propylene glycol monomethyl ether, and the propylene glycol monomethyl ether continuously reacts with the methanol to generate propylene glycol dimethyl ether. If the propylene glycol monomethyl ether and the propylene glycol dimethyl ether are not removed from the system or the removal amount is less than the production amount, the concentration of the extracting agent is reduced, the extraction efficiency of the extracting agent is reduced, the energy consumption of the system is increased, and the purity of the propylene oxide is reduced. Under normal pressure, the boiling point of the propylene oxide is 34 ℃, the boiling point of the extracting agent n-octane is 125.7 ℃, the boiling point of the propylene glycol monomethyl ether is 120.1 ℃, and the boiling point of the propylene glycol dimethyl ether is 93.0 ℃. Therefore, the boiling points of the impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are higher than that of propylene oxide and lower than that of the extracting agent, and the boiling points of the propylene glycol monomethyl ether and n-octane are close to each other, so that a rectifying tower is required to be independently arranged for separation; in addition, the impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether and the extractant C8 alkane form a low-temperature azeotrope, which further increases the separation difficulty.
Document CN100537553C discloses a method for purifying propylene oxide containing methyl formate as an impurity, in which a C7 to C20 hydrocarbon is used as an extractant, and an extractive distillation method is employed, and water is added to a distillate obtained at the top of an extractive distillation column to perform an oil-water separation operation, and the separated oil layer is reused in the extractive distillation column, while the separated water layer is removed to the outside of the system, and propylene oxide having a reduced methyl formate concentration is obtained as a bottom liquid of the extractive distillation column. The technology can be only used for removing light component impurities which can be azeotroped with the extracting agent and have boiling points lower than that of propylene oxide, and the proportion of the impurities in water distribution is far larger than that of the impurities in the extracting agent in phase separation.
Document CN1307168C discloses a method for purifying propylene oxide, in which a reaction solution containing propylene oxide and impurities such as water, hydrocarbons, and oxygen-containing organic compounds, which is obtained by reacting cumene hydroperoxide with propylene, is subjected to extractive distillation in an extractive distillation column using a C7 to C20 hydrocarbon extractant. Further, as a method for reducing the concentration of propylene glycol in the extractant, separation methods such as distillation separation, adsorption, washing, standing separation, and extraction can be mentioned, and washing separation is preferable.
The current situation of the prior art is that a propylene oxide refining method with low investment, low extractant loss, high purity, high propylene oxide yield and low energy consumption is still needed.
Disclosure of Invention
The present inventors have assiduously studied on the basis of the prior art and found that at least one of the above-mentioned problems can be solved by using a low-temperature azeotrope formed by an extraction agent and propylene glycol monomethyl ether and propylene glycol dimethyl ether as impurities and extracting the low-temperature azeotrope from a side line liquid phase of a separation column by using the azeotrope and an azeotropic type, and thus have completed the present invention.
Specifically, the present invention relates to a method for purifying propylene oxide. The method comprises the steps of separating a feed stream containing propylene oxide, an extractant, and propylene glycol monomethyl ether and propylene glycol dimethyl ether in a separation column;
the separation column is operated under conditions sufficient for the extractant to form an azeotrope with propylene glycol monomethyl ether and propylene glycol dimethyl ether, and
collecting the material flow containing extractant-propylene glycol monomethyl ether azeotrope and extractant-propylene glycol dimethyl ether azeotrope from the side line of the separation tower.
According to one aspect of the invention, the conditions sufficient for the extraction agent and propylene glycol monomethyl ether and propylene glycol dimethyl ether to form an azeotrope comprise: the operation pressure at the tower top is 0.02-0.70 MPaG, preferably 0.03-0.50 MPaG; the operation temperature at the top of the tower is 38-110 ℃, and preferably 42-70 ℃.
According to one aspect of the invention, the number N of theoretical plates of the separation column is 15 to 80, preferably 20 to 65, and more preferably 20 to 50.
According to one aspect of the invention, the weight ratio of the extracting agent to the propylene oxide in the feed stream is (2-20): 1, preferably (3-15): 1, more preferably (5-10): 1; the total content of the propylene glycol monomethyl ether and the propylene glycol dimethyl ether is 0.001-2.0% by weight, preferably 0.001-1.5% by weight, and more preferably 0.001-1.0% by weight.
According to one aspect of the invention, the feed stream is derived from an extract product stream obtained by extractive distillation of a propylene epoxidation reaction product.
According to one aspect of the invention, the side-stream of the separation column withdraws the stream containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope at a position between 0.01N and 0.95N, preferably between 0.05N and 0.85N.
According to one aspect of the invention, the flow rate of the material flow containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope, which is extracted from the side line of the separation tower, and the flow rate of the propylene glycol monomethyl ether and the propylene glycol dimethyl ether contained in the raw material flow are in a ratio of (1-10): 1, preferably (1-8): 1, and more preferably (1-4): 1.
According to one aspect of the invention, the separation column side is split into at least two streams, a first stream rich in the extractant-propylene glycol monomethyl ether azeotrope and a second stream rich in the extractant-propylene glycol dimethyl ether azeotrope being withdrawn separately.
According to one aspect of the invention, the second stream withdrawal point is arranged above the first stream withdrawal point.
According to one aspect of the invention, the side-stream of the separation column produces a single stream containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope.
According to one aspect of the invention, the method further comprises: the material flow containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope enters a phase separator, and light phase material flow rich in the extractant and heavy phase material flow rich in propylene glycol monomethyl ether and propylene glycol dimethyl ether are obtained after phase separation; the light phase material flow returns to the separation tower, and the heavy phase material flow is extracted.
According to one aspect of the invention, the material flow containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope is cooled to 35-60 ℃ and then enters the phase separator.
The invention has the beneficial effects that: the method of the invention utilizes the extraction agent and the heavy component impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether to form an azeotrope, and the azeotrope is extracted from the side line of the separation tower, thereby discharging the impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether from the extraction agent circulation system, purifying the circulating extraction agent, improving the purity of the extraction agent, reducing the loss and energy consumption of the extraction agent, and improving the yield of the propylene oxide. Compared with the scheme that the material flow in the tower kettle of the separation tower is directly discharged, the purity of the extracting agent is improved by 0.1-14%, the loss of the extracting agent is only 0.05-1%, the energy consumption is reduced by 1-16%, and the yield of the propylene oxide is improved by 0.5-5%.
Drawings
FIG. 1 is a schematic flow diagram of one embodiment of the present invention.
FIG. 2 is a schematic flow chart of another embodiment of the present invention.
FIG. 3 is a schematic flow chart of another embodiment of the present invention.
FIG. 4 is a schematic flow chart of a comparative example.
In the drawings, like parts are provided with like reference numerals. The drawings are not to scale.
Description of reference numerals:
1 feed stream
2 extractant stream
3 propylene oxide product stream
4 reboiler feed stream
Stream (third stream) containing extractant-propylene glycol monomethyl ether azeotrope and extractant-propylene glycol dimethyl ether azeotrope
8 cooled stream
9 light phase stream rich in extractant
10 heavy phase stream rich in propylene glycol monomethyl ether and propylene glycol dimethyl ether
11 contaminant stream
12 side draw stream (second stream) rich in extractant-propylene glycol dimethyl ether azeotrope
13 side draw stream (first stream) rich in extractant-propylene glycol monomethyl ether azeotrope
A separation tower
B reboiler
C cooler
D phase splitter
The invention is described in detail below with reference to the drawings, but it is to be noted that the scope of the invention is not limited thereto, but is defined by the appended claims.
All publications, patent applications, patents, and other references mentioned in this specification are herein incorporated by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present specification, including definitions, will control.
Where the specification proceeds from the prefix "known to those skilled in the art", "prior art" or similar language to derive materials, substances, methods, procedures, devices or components and the like, the prefix derived object covers those conventionally used in the art at the time of filing this application but also those not currently in use but which would become known in the art to be suitable for a similar purpose.
In the context of the present specification, anything not mentioned or anything else is directly applicable to what is known in the art without any change, except where explicitly stated. Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or concepts resulting therefrom are considered part of the original disclosure or original disclosure of the invention, and should not be considered as new matters not disclosed or contemplated herein, unless one of ordinary skill in the art would recognize that such combination is clearly unreasonable.
Unless otherwise expressly indicated, all percentages, parts, ratios, etc. mentioned in this specification are by weight unless otherwise not in accordance with the conventional knowledge of those skilled in the art.
In the case where no explicit indication is given, the number of theoretical plates mentioned in this specification is calculated from top to bottom, i.e. the overhead condenser is the first theoretical plate and the kettle reboiler is the last theoretical plate.
Reference to pressure within this specification refers to relative pressure unless explicitly indicated.
The feed used in the purification process of the present invention is a stream comprising propylene oxide and an extractant. The stream is derived from an extract product stream obtained after the extractive distillation of the propylene epoxidation reaction product in an extractive distillation column (not shown in the drawing of the invention). In the material flow, the weight ratio of the extracting agent to the propylene oxide is (2-20): 1, preferably (3-15): 1, more preferably (5-10): 1; the total content of the propylene glycol monomethyl ether and the propylene glycol dimethyl ether is 0.001-2.0% by weight, preferably 0.001-1.5% by weight, and more preferably 0.001-1.0% by weight.
The use of extractive agents for the purification of propylene oxide is well known. Generally, C7-C20 straight-chain and branched-chain hydrocarbons and/or glycols are used as the extractant. For economic reasons, mixtures of C8 linear and branched alkanes are used as extractants, for example n-octane, isooctane, 2-methylheptane. The mixture is preferably selected from the viewpoint of reducing the cost of the extractant.
According to the invention, in fig. 1, a material flow 1 containing propylene oxide, an extracting agent and impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether enters a separation tower A, a propylene oxide product material flow 3 is removed from the top of the separation tower, an extracting agent material flow 2 is removed from the bottom of the separation tower, and the removed extracting agent can be returned to a previous extraction rectifying tower (not related to the drawing of the invention) for recycling. The bottom of the separation tower A is provided with a reboiler B, the reboiler B feeds 4 the tower bottom liquid into the reboiler B, a reboiler B discharge material flow 5 is obtained after heating, the discharge material flow 5 is sent back to the lower part of the separation tower A, and a side-draw material flow 7 containing an extractant-propylene glycol monomethyl ether azeotrope and an extractant-propylene glycol dimethyl ether azeotrope is drawn from the side of the separation tower A. Thus, the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are discharged from the system.
The inventor finds that the extracting agent-propylene glycol monomethyl ether azeotrope and the extracting agent-propylene glycol dimethyl ether azeotrope are minimum temperature azeotropes, and the azeotropes are heterogeneous azeotropes. Taking the extracting agent as n-octane as an example, the boiling point of the n-octane is 125.7 ℃, the boiling point of propylene glycol monomethyl ether is 120.1 ℃ and the boiling point of propylene glycol dimethyl ether is 93.0 ℃ under normal pressure; the temperature of the azeotrope of the n-octane and the propylene glycol monomethyl ether is 103.7 ℃, and the azeotropic composition is as follows: 55.67 wt% of n-octane and 44.33 wt% of propylene glycol monomethyl ether; the temperature of the azeotrope of the n-octane and the propylene glycol dimethyl ether is 92.4 ℃, and the azeotropic composition is as follows: 11.89 wt% of n-octane and 88.11 wt% of propylene glycol dimethyl ether. The lowest temperature azeotrope is extracted through a side line, the extracted heterogeneous azeotrope can effectively separate impurities by utilizing a simple and cheap liquid-liquid phase separation process, and meanwhile, the extracting agent is recovered for cyclic utilization.
Along with the increase of the pressure, the content of the extracting agent in the extracting agent-propylene glycol monomethyl ether azeotrope is gradually reduced, and the content of the propylene glycol monomethyl ether is gradually increased; the content of the extractant in the azeotrope is gradually increased and the content of the impurity propylene glycol dimethyl ether is gradually reduced along with the pressure increase of the extractant-propylene glycol dimethyl ether azeotrope. Therefore, as the pressure increases, the content of the impurity propylene glycol monomethyl ether in the azeotrope gradually increases, while the content of the impurity propylene glycol dimethyl ether gradually decreases. That is, as the pressure increases, the propylene glycol monomethyl ether impurity produced increases and the propylene glycol dimethyl ether impurity decreases with the same amount of side draw. Therefore, it is desirable to select an appropriate pressure to minimize extractant loss. The comprehensive consideration is that 0.03-0.50 MPaG is preferred, and the temperature of the corresponding azeotrope is preferably 100-160 ℃. The optimal production composition is the azeotropic composition corresponding to the operation pressure, otherwise, the amount of the extracting agent in the side line production composition is increased, and the loss amount of the direct discharge is increased.
The position for taking out the material flow containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope is positioned between 0.01N and 0.95N, and preferably between 0.05N and 0.85N. At this point, the azeotrope composition had the highest propylene glycol monomethyl ether and propylene glycol dimethyl ether content, with the least amount of propylene oxide and extractant being carried over. The higher the concentration of the propylene oxide and the extracting agent in the azeotrope composition is, and the lower the concentrations of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are, the more the propylene oxide and the extracting agent are brought out when the azeotrope is extracted, the larger the loss is.
The side stream azeotrope can be withdrawn in a single stream or in two streams, preferably in a single stream side stream. Similarly, taking n-octane as an example, the boiling point of the n-octane-propylene glycol monomethyl ether azeotrope is 20-40 ℃ lower than that of n-octane, and the boiling point of the n-octane-propylene glycol dimethyl ether azeotrope is 30-45 ℃ lower than that of n-octane, so in another embodiment of the invention (shown in figure 2), the number of side-drawn material streams is consistent with the number of impurity types. In the raw material of the invention, two impurities exist, so that two side streams are extracted. The two side draws are respectively: a first stream rich in the extractant-propylene glycol monomethyl ether azeotrope, and a second stream rich in the extractant-propylene glycol dimethyl ether azeotrope. The first stream contains the extractant-propylene glycol monomethyl ether azeotrope, the extractant-propylene glycol dimethyl ether azeotrope, but is rich in the extractant-propylene glycol monomethyl ether azeotrope and is the highest concentration of propylene glycol monomethyl ether in the extractant-propylene glycol monomethyl ether azeotrope. The second stream comprises the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope, but is rich in the extractant-propylene glycol dimethyl ether azeotrope and is the highest concentration of propylene glycol dimethyl ether in the extractant-propylene glycol dimethyl ether azeotrope. The second material flow extraction outlet is arranged at the upper part of the first material flow extraction outlet.
Fig. 3 is a preferred embodiment of the present invention. Cooling a material flow 7 containing an extractant-propylene glycol monomethyl ether azeotrope and an extractant-propylene glycol dimethyl ether azeotrope, then feeding the cooled material flow into a phase separator, and performing phase separation to obtain a light phase material flow rich in the extractant and a heavy phase material flow rich in propylene glycol monomethyl ether and propylene glycol dimethyl ether; the light phase material flow returns to the separation tower, and the heavy phase material flow is extracted. The technical scheme that the light phase rich in the extractant is returned to the separation tower after the side line extraction is cooled and phase-separated can greatly improve the purity of the extractant and simultaneously reduce the loss of the extractant.
FIG. 4 shows the prior art, a material flow 1 containing propylene oxide, an extracting agent and impurities enters a separation tower A, a propylene oxide product material flow 3 is removed from the top of the separation tower A, an extracting agent material flow 2 is removed from the bottom of the separation tower A, a reboiler B is arranged at the bottom of the separation tower A, tower bottom liquid is fed into the reboiler B by a reboiler B feeding material flow 4, a reboiler B discharging material flow 5 is obtained after heating, the discharging material flow 5 is fed into the lower part of the separation tower A, and a material flow 11 is separated from the extracting agent material flow 2, so that the impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are discharged out of the system. A greater amount of extractant is lost due to the reduction in the accumulation of impurities in the extractant by the discharge of a portion of the bottoms stream.
The invention is further illustrated by the following specific embodiments.
Detailed Description
[ example 1 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.0 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the 7 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.02MPaG, the temperature is 40 ℃, the side-draw temperature is 100 ℃, the contents of propylene glycol monomethyl ether and propylene glycol dimethyl ether impurities are 52.85 wt%, and the side-draw impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are enriched and extracted.
According to the process flow shown in fig. 1, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.95%, the purity of the extractant at the bottom of the separation tower is 99.79%, and the loss of the extractant is 0.210%.
According to the process flow shown in fig. 2, the positions of the side line extraction are respectively selected to have the maximum contents of propylene glycol monomethyl ether and propylene glycol dimethyl ether as impurities, namely the 17 th theoretical plate is used for extracting propylene glycol monomethyl ether as an impurity, wherein the azeotropic temperature is 112 ℃, the content of the propylene glycol monomethyl ether as an impurity is 38.73%, and the content of the propylene glycol dimethyl ether as an impurity is 0.25%; the 5 th plate extracts propylene glycol dimethyl ether as impurities, wherein the azeotropic temperature is 78 ℃, the content of the propylene glycol monomethyl ether is 15.64 percent, the content of the propylene glycol dimethyl ether is 38.27 percent, and the total amount of the two extracted impurities is 47.20 percent.
According to the process flow shown in fig. 2, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.90%, the purity of the extractant at the bottom of the separation tower is 99.78%, and the loss of the extractant is 0.207%.
Under the condition that the total amount of the side offtake is the same, 11.86% more impurities are extracted according to the process flow shown in the figure 1 than the process flow shown in the figure 2, and because the 1, 2-propylene oxide is extracted from the side in the process flow shown in the figure 2, the recovery rate of the 1, 2-propylene oxide is reduced, and the loss rate of the extracting agent is slightly reduced.
[ example 2 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.0 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the 7 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.05MPaG, the temperature is 46 ℃, the side-draw temperature is 106 ℃, the contents of propylene glycol monomethyl ether and propylene glycol dimethyl ether impurities are 52.58 wt%, and the side-draw impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are enriched and withdrawn.
The purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.94%, the purity of the extractant at the bottom of the separation tower is 99.79%, and the loss of the extractant is 0.210%.
[ example 3 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.0 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the 7 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.10MPaG, the temperature is 55 ℃, the side-draw temperature is 116 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 52.10 wt%, and the side-draw impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are collected in an enrichment way.
The purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.93%, the purity of the extractant at the bottom of the separation tower is 99.79%, and the loss of the extractant is 0.211%.
[ example 4 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.0 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the 7 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.25MPaG, the temperature is 74 ℃, the side-draw temperature is 135 ℃, the contents of propylene glycol monomethyl ether and propylene glycol dimethyl ether impurities in the side-draw are 50.83 wt%, and the propylene glycol monomethyl ether and propylene glycol dimethyl ether impurities in the side-draw are enriched and withdrawn.
The purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.92%, the purity of the extractant at the bottom of the separation tower is 99.78%, and the loss of the extractant is 0.215%.
[ example 5 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.0 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the 7 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.50MPaG, the temperature is 96 ℃, the side-draw temperature is 161 ℃, the contents of impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 49.5 wt%, and the side-draw impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are enriched and extracted.
The purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.90%, the purity of the extractant at the bottom of the separation tower is 99.78%, and the loss of the extractant is 0.221%.
[ example 6 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.0 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the 7 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.65MPaG, the temperature is 105 ℃, the side-draw temperature is 166 ℃, the contents of propylene glycol monomethyl ether and propylene glycol dimethyl ether impurities are 49.06 wt%, and the side-draw impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are enriched and extracted.
The purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.89%, the purity of the extractant at the bottom of the separation tower is 99.77%, and the loss of the extractant is 0.225%.
[ example 7 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.0 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 5:1, the number of theoretical plates of the separation tower is 30, and the 8 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.02MPaG, the temperature is 40 ℃, the side-draw temperature is 107 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 54.85 wt%, and the side-draw impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are collected in an enrichment way.
According to the process flow shown in fig. 1, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.89%, and the loss of the extractant is 0.109%.
[ example 8 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.5% by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 10:1, the number of theoretical plates in the separation tower is 40, and the 8 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.02MPaG, the temperature is 40 ℃, the side-draw temperature is 101 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 55.35 wt%, and the side-draw impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are collected in an enrichment way.
According to the process flow shown in fig. 1, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.97%, the recovery rate is 99.97%, the purity of the extractant at the bottom of the separation tower is 99.96%, and the loss of the extractant is 0.0428%.
[ example 9 ]
According to the process flow shown in fig. 1, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.5 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 15:1, the number of theoretical plates of the separation tower is 50, and the side line extraction of the separation tower is positioned on the 10 th theoretical plate. The operating pressure of the separation tower is 0.02MPaG, the temperature is 40 ℃, the side-draw temperature is 102 ℃, the contents of propylene glycol monomethyl ether and propylene glycol dimethyl ether impurities are 55.48 wt%, and the side-draw impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are enriched and extracted.
According to the process flow shown in fig. 1, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.97%, the recovery rate is 99.97%, the purity of the extractant at the bottom of the separation tower is 99.97%, and the loss of the extractant is 0.0285%.
[ example 10 ]
According to the process flow shown in fig. 1, the extraction agent is 2-methylheptane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 1.5 percent by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the theoretical plate at the 6 th position is taken out from the side line of the separation tower. The operating pressure of the separation tower is 0.02MPaG, the temperature is 40 ℃, the side-draw temperature is 91 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 46.91 wt%, and the side-draw impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are collected in an enrichment way.
According to the process flow shown in fig. 1, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.91%, the purity of the extractant at the bottom of the separation tower is 99.75%, and the loss of the extractant is 0.247%.
[ example 11 ]
According to the process flow shown in fig. 1, the extraction agent is isooctane, and in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether, the contents of the impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are 1.5% by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the 16 th theoretical plate is taken from the side line of the separation tower. The operating pressure of the separation tower is 0.02MPaG, the temperature is 40 ℃, the side-draw temperature is 97 ℃, the contents of impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 27.63 wt%, and the side-draw impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are enriched and extracted.
According to the process flow shown in fig. 1, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.90%, the purity of the extractant at the bottom of the separation tower is 99.64%, and the loss of the extractant is 0.360%.
[ example 12 ]
According to the process flow shown in fig. 3, the extractant is n-octane, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extractant and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extractant to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates in the separation tower is 20, and the 9 th theoretical plate is taken from the side line of the separation tower.
The flow rate of the azeotrope material flow extracted from the side line is 1.5 of the flow rate of the impurities contained in the feeding material flow: 1; the pressure of the azeotrope extracted from the side line is 0.028MPaG, the azeotropic temperature is 104 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 50.26wt percent, and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the side line are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.96%, the recovery rate is 99.96%, the purity of the extractant at the bottom of the separation tower is 99.88%, and the loss of the extractant is 0.1523%.
[ example 13 ]
According to the process flow shown in fig. 3, the extractant is n-octane, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extractant and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extractant to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates in the separation tower is 20, and the 14 th theoretical plate is taken from the side line of the separation tower.
The flow rate of the azeotrope material flow extracted from the side line is 2.5 of the flow rate of the impurities contained in the feeding material flow: 1; the pressure of the azeotrope extracted from the side line is 0.034MPaG, the azeotropic temperature is 109 ℃, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 46.35 wt%, and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the side line are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.99%, and the loss of the extractant is 0.1546%.
[ example 14 ]
According to the process flow shown in fig. 3, the extractant is n-octane, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extractant and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extractant to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates in the separation tower is 20, and the 14 th theoretical plate is taken from the side line of the separation tower.
The flow rate of the azeotrope material flow extracted from the side line is 3.5 of the flow rate of the impurities contained in the feeding material flow: 1; the pressure of the azeotrope extracted from the side line is 0.034MPaG, the azeotropic temperature is 108 ℃, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 37.02 wt%, and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the side line are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.99%, and the loss of the extractant is 0.1550%.
[ example 15 ]
According to the process flow shown in fig. 3, the extractant is n-octane, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extractant and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extractant to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates in the separation tower is 20, and the 14 th theoretical plate is taken from the side line of the separation tower.
The flow rate of the side-draw azeotrope material flow is 4.5 of the flow rate of the impurities contained in the feed material flow: 1; the pressure of the azeotrope extracted from the side line is 0.034MPaG, the azeotropic temperature is 108 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 31.84 wt%, and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the side line are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.99%, and the loss of the extractant is 0.1552%.
[ example 16 ]
According to the process flow shown in fig. 3, the extractant is n-octane, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extractant and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extractant to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates in the separation tower is 20, and the 14 th theoretical plate is taken from the side line of the separation tower.
The flow rate of the azeotrope material flow extracted from the side line is 8 of the flow rate of the impurities contained in the feeding material flow: 1; the pressure of the azeotrope extracted from the side line is 0.034MPaG, the azeotropic temperature is 108 ℃, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 23.90 wt%, and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the side line are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.99%, and the loss of the extractant is 0.1556%.
[ example 17 ]
According to the process flow shown in fig. 3, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 4:1, the number of theoretical plates of the separation tower is 30, and the 21 st theoretical plate is taken from the side line of the separation tower.
The flow rate of the side-draw azeotrope material flow is 4.5 of the flow rate of the impurities contained in the feed material flow: 1; the pressure of the azeotrope extracted from the side line is 0.034MPaG, the azeotropic temperature is 108 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 31.94 wt%, and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the side line are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.99%, and the loss of the extractant is 0.1492%.
[ example 18 ]
According to the process flow shown in fig. 3, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 7:1, the number of theoretical plates in the separation tower is 35, and the 21 st theoretical plate is taken from the side line of the separation tower.
The flow rate of the side-draw azeotrope material flow is 4.5 of the flow rate of the impurities contained in the feed material flow: 1; the pressure of the azeotrope extracted from the side line is 0.314MPaG, the azeotropic temperature is 151 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 31.92wt percent, and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the side line are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.99%, and the loss of the extractant is 0.1153%.
[ example 19 ]
According to the process flow shown in fig. 3, the extraction agent is n-octane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 9:1, the number of theoretical plates in the separation tower is 45, and the 21 st theoretical plate is taken from the side line of the separation tower.
The flow rate of the side-draw azeotrope material flow is 4.5 of the flow rate of the impurities contained in the feed material flow: 1; the pressure of the azeotrope extracted from the side line is 0.514MPaG, the azeotropic temperature is 168 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 31.89 wt%, and the side line impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.99%, and the loss of the extractant is 0.1055%.
[ example 20 ]
According to the process flow shown in fig. 3, the extraction agent is 2-methylheptane, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extraction agent to the 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 20, and the 10 th theoretical plate is taken from the side line of the separation tower.
The flow rate of the side-draw azeotrope material flow is 4.5 of the flow rate of the impurities contained in the feed material flow: 1; the pressure of the azeotrope extracted from the side line is 0.03MPaG, the azeotropic temperature is 103 ℃, the contents of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether are 40.77 wt%, and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the side line are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.88%, the purity of the extractant at the bottom of the separation tower is 99.75%, and the loss of the extractant is 1.086%.
[ example 21 ]
According to the process flow shown in fig. 3, the extraction agent is isooctane, and in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether, the contents of the impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are 0.8% by weight, the ratio of the extraction agent to 1, 2-propylene oxide is 2.1:1, the number of theoretical plates of the separation tower is 30, and the 9 th theoretical plate is taken from the side line of the separation tower.
The flow rate of the side-draw azeotrope material flow is 4.5 of the flow rate of the impurities contained in the feed material flow: 1; the pressure of the azeotrope extracted from the side line is 0.03MPaG, the azeotropic temperature is 95 ℃, the contents of propylene glycol monomethyl ether and propylene glycol dimethyl ether impurities are 26.11 wt%, and the side line impurities of propylene glycol monomethyl ether and propylene glycol dimethyl ether are enriched and extracted.
According to the process flow shown in fig. 3, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.95%, the recovery rate is 99.98%, the purity of the extractant at the bottom of the separation tower is 99.56%, and the loss of the extractant is 1.451%.
[ COMPARATIVE EXAMPLE 1 ]
According to the process flow diagram shown in fig. 4, the extraction agent is n-octane, the content of propylene glycol monomethyl ether and propylene glycol dimethyl ether as impurities in a material flow containing 1, 2-propylene oxide, the extraction agent and propylene glycol monomethyl ether and propylene glycol dimethyl ether as impurities is 0.8% by weight, the ratio of the extraction agent to 1, 2-propylene oxide is 2.1:1, the theoretical plate number of the separation tower is 20, and an impurity material flow is collected from the bottom of the separation tower. The operating pressure of the separation tower is 0.02MPaG, the temperature is 40 ℃, the temperature of the impurity material flow extracted from the tower kettle is 134 ℃, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.478 percent by weight, and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether are extracted.
According to the process flow shown in fig. 4, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.52%, and the loss of the extractant is 0.479%.
[ COMPARATIVE EXAMPLE 2 ]
According to the process flow diagram shown in fig. 4, the extraction agent is 2-methylheptane, the content of the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether in the material flow containing 1, 2-propylene oxide, the extraction agent and the impurities propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.8% by weight, the ratio of the extraction agent to 1, 2-propylene oxide is 2.1:1, the theoretical plate number of the separation tower is 20, and the impurity material flow is extracted from the bottom of the separation tower. The operating pressure of the separation tower is 0.02MPaG, the temperature is 40 ℃, the temperature of the impurity material flow extracted from the tower kettle is 127 ℃, the content of the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether is 0.478 percent by weight, and the impurity propylene glycol monomethyl ether and propylene glycol dimethyl ether are extracted.
According to the process flow shown in fig. 4, the purity of the 1, 2-epoxypropane product obtained at the top of the separation tower is 99.99%, the recovery rate is 99.99%, the purity of the extractant at the bottom of the separation tower is 99.52%, and the loss of the extractant is 0.479%.
Claims (15)
1. A method for refining propylene oxide comprises the steps of separating a feed stream containing propylene oxide, an extractant, propylene glycol monomethyl ether and propylene glycol dimethyl ether in a separation column;
the separation column is operated under conditions sufficient for the extractive agent and propylene glycol monomethyl ether, propylene glycol dimethyl ether to form an azeotrope, and
collecting a material flow containing an extractant-propylene glycol monomethyl ether azeotrope and an extractant-propylene glycol dimethyl ether azeotrope from the side line of the separation tower;
the position of the material flow which contains the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope and is extracted from the side line of the separation tower is positioned between 0.05N and 0.85N;
the conditions sufficient for the extraction agent and propylene glycol monomethyl ether, propylene glycol dimethyl ether to form an azeotrope include: the operation pressure at the top of the tower is 0.03-0.50 MPaG, and the operation temperature at the top of the tower is 42-70 ℃;
the extractant is C8A mixture of linear and branched alkanes;
the method further comprises the following steps: the material flow containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope enters a phase separator, and light phase material flow rich in the extractant and heavy phase material flow rich in propylene glycol monomethyl ether and propylene glycol dimethyl ether are obtained after phase separation; the light phase material flow returns to the separation tower, and the heavy phase material flow is extracted.
2. The method for purifying propylene oxide according to claim 1, wherein the number N of theoretical plates of the separation column is 15 to 80.
3. The method for purifying propylene oxide according to claim 2, wherein the number N of theoretical plates of the separation column is 20 to 65.
4. The method for purifying propylene oxide according to claim 3, wherein the number N of theoretical plates of the separation column is 20 to 50.
5. The propylene oxide refining method according to claim 1, wherein the weight ratio of the extractant to the propylene oxide in the raw material stream is (2-20): 1; the total content of the propylene glycol monomethyl ether and the propylene glycol dimethyl ether is 0.001-2.0% by weight.
6. The propylene oxide refining method according to claim 5, wherein the weight ratio of the extractant to the propylene oxide in the raw material stream is (3-15): 1; the total content of the propylene glycol monomethyl ether and the propylene glycol dimethyl ether is 0.001-1.5% by weight.
7. The propylene oxide refining method according to claim 6, wherein the weight ratio of the extractant to the propylene oxide in the raw material stream is (5-10): 1; the total content of the propylene glycol monomethyl ether and the propylene glycol dimethyl ether is 0.001-1.0% by weight.
8. The method for purifying propylene oxide according to claim 1, wherein said feed stream is derived from an extract product stream obtained by extractive distillation of a product of epoxidation of propylene.
9. The method for refining propylene oxide according to claim 1, wherein the ratio of the flow rate of the stream containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope, which is collected from the side of the separation column, to the flow rate of the propylene glycol monomethyl ether and propylene glycol dimethyl ether contained in the raw material stream is (1-10): 1.
10. The method for refining propylene oxide according to claim 9, wherein the ratio of the flow rate of the stream containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope, which is collected from the side of the separation column, to the flow rate of the propylene glycol monomethyl ether and propylene glycol dimethyl ether contained in the raw material stream is (1-8): 1.
11. The method for refining propylene oxide according to claim 10, wherein the ratio of the flow rate of the stream containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope, which is collected from the side of the separation column, to the flow rate of the propylene glycol monomethyl ether and propylene glycol dimethyl ether contained in the raw material stream is (1-4): 1.
12. The process for purifying propylene oxide according to claim 1, wherein the separation column side is divided into at least two streams, and a first stream rich in the extractant-propylene glycol monomethyl ether azeotrope and a second stream rich in the extractant-propylene glycol dimethyl ether azeotrope are withdrawn separately.
13. The method for purifying propylene oxide according to claim 12, wherein the second stream take-off port is disposed at an upper portion of the first stream take-off port.
14. The process for purifying propylene oxide according to claim 1, wherein a third stream containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope is separately withdrawn from the side stream of the separation column.
15. The method for purifying propylene oxide according to claim 1, wherein the material flow containing the extractant-propylene glycol monomethyl ether azeotrope and the extractant-propylene glycol dimethyl ether azeotrope is cooled to 35 to 60 ℃ and then enters the phase separator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711241043 | 2017-11-30 | ||
| CN2017112410439 | 2017-11-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109851588A CN109851588A (en) | 2019-06-07 |
| CN109851588B true CN109851588B (en) | 2021-05-11 |
Family
ID=66889546
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810153538.4A Active CN109851588B (en) | 2017-11-30 | 2018-02-22 | Method for purifying propylene oxide |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109851588B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110330413B (en) * | 2019-07-31 | 2022-08-09 | 惠生工程（中国）有限公司 | Method for recovering propylene glycol monomethyl ether in alcohol ether aqueous solution material flow |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1307168A (en) * | 2000-01-27 | 2001-08-08 | 张立民 | Hooked-head lock |
| CN104109137A (en) * | 2013-04-16 | 2014-10-22 | 中国石油化工股份有限公司 | Epoxypropane purifying method |
-
2018
- 2018-02-22 CN CN201810153538.4A patent/CN109851588B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1307168A (en) * | 2000-01-27 | 2001-08-08 | 张立民 | Hooked-head lock |
| CN104109137A (en) * | 2013-04-16 | 2014-10-22 | 中国石油化工股份有限公司 | Epoxypropane purifying method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109851588A (en) | 2019-06-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109851586B (en) | Process for purifying propylene oxide | |
| CN104109137B (en) | Oxide purification process | |
| CA1166595A (en) | Method of producing ethanol-water azeotrope from crude ethanol | |
| CN109111337B (en) | Separation equipment and method for mixed solvent containing toluene, ethyl acetate, ethanol and the like | |
| CN109206291A (en) | A kind of separation method of chloromethanes-dimethyl ether | |
| CN109851589B (en) | Propylene oxide purification method and purification apparatus | |
| CN106397361A (en) | Purifying method for 1,2-epoxybutane | |
| CN109851576B (en) | Method and apparatus for purifying butylene oxide | |
| CN109851588B (en) | Method for purifying propylene oxide | |
| US11591303B2 (en) | Method and system for producing epoxyalkane | |
| CN105085165B (en) | The separation method of ethylene glycol and diethylene glycol | |
| CN106397365B (en) | 1,2- epoxy butane purification devices | |
| CN109851581B (en) | Method for purifying butylene oxide | |
| CN109851582A (en) | The purification process of propylene oxide | |
| CN109851579B (en) | Process for producing alkylene oxide | |
| CN109851577B (en) | Method for purifying butylene oxide | |
| CN106397184A (en) | Method for dewatering solvent during aromatic acid production process | |
| CN109851574B (en) | Method for producing propylene oxide | |
| CN109851591B (en) | Method and apparatus for purifying alkylene oxide | |
| CN109851578A (en) | The purification process of epoxy butane | |
| CN109851587B (en) | Method for producing butylene oxide | |
| CN109851590A (en) | The purification process of propylene oxide | |
| CN106866409B (en) | Method for extracting and recovering dilute acetic acid from cyclohexyl acetate | |
| CN107286118A (en) | The refining plant of expoxy propane | |
| CN109851584B (en) | Method and apparatus for purifying alkylene oxide |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |