CN103172596B - Propylene oxide refining method - Google Patents
Propylene oxide refining method Download PDFInfo
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- CN103172596B CN103172596B CN201110434194.2A CN201110434194A CN103172596B CN 103172596 B CN103172596 B CN 103172596B CN 201110434194 A CN201110434194 A CN 201110434194A CN 103172596 B CN103172596 B CN 103172596B
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Abstract
The invention provides a propylene oxide refining method. The method is characterized by comprising the steps that an epoxidation reaction product enters a propylene separating column to be separated into column top materials and column bottom materials, wherein the column top materials contain propylene, propylene oxide and methanol and contain or do not contain propane and water, and the column bottom materials contain methanol, water, hydrogen peroxide and high-boiling-point byproducts; column top materials from the propylene separating column enter a propylene stripping column to remove propylene and propane out of the column top materials, and the column top gases after stripping contain propylene and little propylene oxide and contain or do not contain propane, enter a propylene oxide absorption column to come into contact with an absorbent to remove propylene oxide and then go back to a reaction system after compression; and column bottom materials from the propylene stripping column contain propylene oxide and methanol and contain or do not contain water and are further fractionated to obtain the high-purity propylene oxide product. The invention also provides a separation method for preparing propylene oxide and the product thereof through direct epoxidation. The method provided by the invention has the beneficial effects that the low temperature and low pressure process is adopted, thus increasing the yield of propylene oxide, reducing the losses of propylene oxide and reducing the operating costs of the devices.
Description
Technical field
The present invention relates to a kind of process for purification of propylene oxide, more particularly, relate to a kind of method that hydrogen peroxide and propylene react refining propylene oxide in the reaction product preparing propylene oxide.
Background technology
Propylene oxide (Propylene Oxide) is the important source material of organic synthesis, is the third-largest acryloyl derivative except polypropylene and vinyl cyanide.It is mainly for the production of polyethers, propylene glycol, propylene glycol etc., is also the important source material of nonionogenic tenside, oil field demulsifier, farm chemical emulgent etc.The derivative of propylene oxide is also widely used in the industries such as food, tobacco, agricultural chemicals and makeup.The derived product of having produced nearly hundred kinds is the important source material of fine chemical product.
Synthesis of Propylene Oxide mainly contains chlorohydrination, conjugated oxidation and direct oxidation method, first two production method all exist cost high, pollute the defects such as large.The main problem of chlorohydrination is that equipment corrosion is serious, and produces waste water, the waste residue of a large amount of organic chloride in producing, contaminate environment.Conjugated oxidation has long flow path, investment is large, byproduct is many, by problems such as oil crisis, energy shortage, the restrictions of byproduct outlet; Direct oxidation rule is under the effect of titanium-silicon molecular sieve catalyst, uses the method for hydrogen peroxide direct oxidation propylene synthesizing epoxypropane.The method has mild condition, technique is simple, product selectivity good and the feature such as environmental friendliness, and therefore titanium molecular sieve catalysis epoxidation of propylene synthesizing epoxypropane is considered to the development trend of propylene oxide synthetic technology.
Excessive propylene, as solvent, is dissolved in methanol solution and reacts with hydrogen peroxide by the methyl alcohol that in the Direct Epoxidation technique of propylene and hydrogen peroxide, general employing is a large amount of, thus ensures the transformation efficiency of higher hydrogen peroxide and the selectivity of propylene oxide.Although the Direct Epoxidation reaction of propylene and hydrogen peroxide has very high selectivity and transformation efficiency, but there is a large amount of solvent, water and unreacted propylene in reaction product, generate a small amount of but miscellaneous aldehyde, ether, alcohol, ketone etc. in addition in reaction process high boiling point by-products produced, make the refining very difficult of propylene oxide.Meanwhile, in product rectifying, propylene oxide can generate the impurity such as ether with other substance reaction of water and hydroxyl at a higher temperature, decreases the yield of propylene oxide, and therefore propylene oxide refining is the committed step in direct oxidation method technique.
Direct Epoxidation reaction product contains a large amount of solvent, unreacting propylene, propylene oxide, water and other impurity, below patent document discloses the method for different refining propylene oxide:
US5599955 is separated and refines Direct Epoxidation reaction product by continuous still battery step.CN1398262A, US6024840, EP2168953 adopt comprise rectifying tower, propylene stripping tower, extractive distillation column combine flow process refine Direct Epoxidation product, obtain propylene oxide.US6881853 discloses a kind of employing two knockout towers, and the flow process on a propylene absorption tower is separated the method for Direct Epoxidation reaction product.US7863468 discloses a kind of method of producing propylene oxide and comprises two rectifying tower, is separated by propylene oxide, then refines propylene oxide, crude carbinol and propylene respectively with non-condensable gases such as propylene.The method needs the reflux ratio of control first rectifying tower, is controlled in 0.5% (weight ratio) below by the water-content in tower top material.
In sum, in the product separation process of Direct Epoxidation reaction, for suppress propylene oxide at a higher temperature with the reaction of water and hydroxyl material, existing separation method substantially all adopts the mode of being discharged from tower top with propylene by propylene oxide in first distillation tower after reactor, shortens the residence time of propylene oxide in tower as far as possible and reduces service temperature.In first overhead material except propylene oxide and propylene, also containing some solvent and/or a small amount of water, and the impurity such as acetaldehyde, therefore tower top material also needs to enter propylene stripping tower again and makes propylene and propylene oxide and separated from solvent, the propylene that propylene stripper overhead material is discharged after partial condensation generally needs to remove the propylene oxide wherein carried secretly before compression, and the propylene oxide of discharging at the bottom of tower and solvent need carry out extracting rectifying and carry out refining further just obtaining product.The flow process that propylene oxide is refined is longer, energy consumption is higher.
Summary of the invention
One of the technical problem to be solved in the present invention is to provide the process for purification of the Direct Epoxidation reaction product that a kind of propylene oxide yield is high, separation process simplifies and plant energy consumption is low.
Two of the technical problem that will solve of the present invention is to provide a kind of the Direct Epoxidation reaction and the separation method that use titanium-silicon molecular sieve catalyst.
The process for purification of a kind of propylene oxide provided by the invention, comprising:
Reaction product from epoxidation reactor enters propylene separation tower and is separated, the tower top material obtained contain propylene, containing or containing propane, propylene oxide, methyl alcohol, containing or not moisture, materials at bottom of tower contains methyl alcohol, water, hydrogen peroxide and high boiling point by-products produced; Propylene separation column overhead material enters propylene stripping tower, overhead gas contains propylene, contains or does not contain propane, a small amount of propylene oxide, enter in propylene oxide absorption tower to contact with absorption agent and remove propylene oxide, then circulation Returning reacting system recycles after compression; Propylene stripper bottoms material contain methyl alcohol, propylene oxide, containing or not moisture, further fractionation obtains highly purified product propylene.
A kind of Direct Epoxidation provided by the invention prepares propylene oxide and product separation method, comprising:
(1) hydrogen peroxide and propylene mixed dissolution in organic solvent, contact with titanium-silicon molecular sieve catalyst in epoxidation reactor and carry out epoxidation reaction, obtain the reaction product containing propylene oxide, described reaction product comprises propane, propylene, propylene oxide, organic solvent, water and high boiling point by-products produced on a small quantity;
(2) reaction product from epoxidation reactor enters the separation of propylene separation tower, the tower top material obtained contain propylene, containing or containing propane, propylene oxide, methyl alcohol, containing or not moisture, materials at bottom of tower contains methyl alcohol, water, hydrogen peroxide and high boiling point by-products produced; Propylene separation column overhead material enters propylene stripping tower, and overhead gas contains propylene, contains or do not contain propane and a small amount of propylene oxide, enters in propylene oxide absorption tower to contact with absorption agent to remove propylene oxide, and then Returning reacting system recycles after compression; Propylene stripper bottoms material contain methyl alcohol, propylene oxide, containing or not moisture, further fractionation obtains highly purified product propylene.
The process for purification of a kind of propylene oxide provided by the invention and the beneficial effect of Direct Epoxidation and separation method are:
Compared with prior art, method provided by the invention adopts low-temp low-pressure technique when carrying out product propylene and refining, and can guarantee that propylene oxide is fully separated from reaction product, and improve the yield of propylene oxide; Adopt methyl alcohol as the absorption agent of propylene oxide absorption tower, the product after absorption returns propylene separation tower and reclaims propylene wherein and propylene oxide, reduce further the loss of propylene and propylene oxide; Extraction liquid at the bottom of extractive distillation column tower containing propylene oxide, can directly not delivered to methanol rectifying tower and be separated, decrease the loss of propylene oxide, reduce the process cost of device.
Accompanying drawing explanation
Accompanying drawing is the schematic flow sheet of a kind of embodiment of method of purifying propylene oxide provided by the invention.
Embodiment
A kind of method of purifying propylene oxide provided by the invention, and Direct Epoxidation reaction and separation method are specifically implemented like this:
A kind of method of purifying propylene oxide, reaction product from epoxidation reactor enters propylene separation tower, be separated the tower top material that obtains contain propylene, containing or containing propane, propylene oxide, methyl alcohol, containing or not moisture, materials at bottom of tower contains methyl alcohol, water, hydrogen peroxide and high boiling point by-products produced; Propylene separation column overhead material enters propylene stripping tower, stripping removes propylene, propane wherein, overhead gas after stripping contains propylene, contains or does not contain propane, a small amount of propylene oxide, enter in propylene oxide absorption tower to contact with absorption agent and remove propylene oxide, then Returning reacting system recycles after compression; Propylene stripper bottoms material contain propylene oxide, methyl alcohol, containing or not moisture, further fractionation obtains highly purified product propylene.
In method provided by the invention, the pressure of described propylene separation tower is 0.1MPa-0.5MPa, preferably 0.15MPa-0.3MPa, reflux ratio is 0-3, preferably 0.1-1, and tower top temperature is 60 DEG C-90 DEG C, preferably 70 DEG C-85 DEG C, and column bottom temperature is 80 DEG C-110 DEG C, preferably 85 DEG C-100 DEG C.
In method provided by the invention, with weight, described propylene separation column overhead material contains the water of the propylene of 15%-50%, the propane of 0-10%, the propylene oxide of 10%-50%, the methyl alcohol of 5%-50% and 0-10%; Described propylene separation tower materials at bottom of tower contains the high boiling point by-products produced of the methyl alcohol of 30%-90%, the water of 20%-50%, the hydrogen peroxide of 0.1%-1% and 0.1%-5%.
In method provided by the invention, described propylene pressure of stripping tower is 0.1MPa-0.4MPa, is preferably 0.15MPa-0.3MPa, and bottom temperature is 55 DEG C-80 DEG C.
In method provided by the invention, described propylene stripper bottoms stream contains the methyl alcohol of 10%-65%, the propylene oxide of 20%-60%, and remaining is high boiling point by-products produced, containing or not moisture.
In method provided by the invention, the pressure of described propylene oxide absorption tower is 0.1MPa-0.5MPa, is preferably 0.15MPa-0.35Mpa.
In method provided by the invention, the absorption agent in described propylene oxide absorption tower is selected from the mixture of one or more in water, alcohol, glycol and glycol ethers.Preferred absorption agent is methyl alcohol.
In method provided by the invention, described propylene stripper bottoms stream and extraction agent enter extractive distillation column, under extracting rectifying condition, extracting rectifying column overhead obtains the extremely low product propylene of methanol content, obtains the mixture of methyl alcohol and extraction agent at the bottom of extractive distillation column tower.
In method provided by the invention, the pressure of described extractive distillation column is 0.1-0.5MPa, preferably 0.1-0.3MPa, and reflux ratio is 1-10.
In method provided by the invention, described extraction agent is selected from the mixture of one or more in water, propylene glycol and the trimethyl carbinol.Preferred extraction agent is water.
A kind of Direct Epoxidation prepares propylene oxide and product separation method, comprising:
(1) hydrogen peroxide and propylene mixed dissolution in organic solvent, contact with titanium-silicon molecular sieve catalyst in epoxidation reactor and carry out epoxidation reaction, obtain the reaction product containing propylene oxide, described reaction product comprises propane, propylene, propylene oxide, organic solvent, water and high boiling point by-products produced on a small quantity;
(2) reaction product from epoxidation reactor enters the separation of propylene separation tower, the tower top material obtained contain propylene, containing or containing propane, propylene oxide, methyl alcohol, containing or not moisture, materials at bottom of tower contains methyl alcohol, water, hydrogen peroxide and high boiling point by-products produced; Propylene separation column overhead material enters propylene stripping tower, overhead gas contain propylene, containing or not containing propane, a small amount of propylene oxide, enter in propylene oxide absorption tower to contact with absorption agent and remove propylene oxide Posterior circle and use; Propylene stripper bottoms material contain methyl alcohol, propylene oxide, containing or not moisture, further fractionation obtains highly purified product propylene.
The Direct Epoxidation of use titanium-silicon molecular sieve catalyst provided by the invention reacts the step preparing propylene oxide and is: hydrogen peroxide raw material and propylene feedstocks mixed dissolution in organic solvent, contact with titanium-silicon molecular sieve catalyst in epoxidation reactor and carry out epoxidation reaction, hydrogen peroxide oxidation propylene, generate propylene oxide and water, and it is high boiling point by-products produced to generate propylene glycol, propylene glycol, contracting propylene glycol etc., the reaction product obtained comprises propane, propylene, propylene oxide, organic solvent, water and high boiling point by-products produced on a small quantity.
In method provided by the invention, the organic solvent of the preferred boiling point of described organic solvent between propylene oxide and water, comprises the alcohols such as methyl alcohol, ethanol or the trimethyl carbinol, preferably uses methyl alcohol as solvent.In solvent, the weight percentage of methyl alcohol is 50%-100%, preferred 90%-100%, can containing a small amount of impurity as ethanol and propyl alcohol etc.Described hydrogen peroxide raw material uses with the form of the aqueous solution of the hydrogen peroxide containing 5%-75%, preferably uses by the hydrogen peroxide product containing 20%-55% of anthraquinone preparation.Described propylene feedstocks, except propylene, can contain the propane of 0%-15%.
In method provided by the invention, the operational condition of described epoxidation reactor is: temperature is 10 DEG C-80 DEG C, preferably 25 DEG C-55 DEG C, pressure is 1.5MPa-5.0MPa, uses excessive propylene and the pH value controlling solution reaches more than 90% to make the transformation efficiency of hydrogen peroxide.For ensureing that propylene and hydrogen peroxide fully dissolve under reaction pressure, the usage quantity of solvent, through preferably, makes the hydrogen peroxide of every mole and the solvent of 1-15 mole.
Described titanium-silicon molecular sieve catalyst is HTS powder, or HTS and carrier-bound titanium-silicon molecular sieve catalyst, wherein HTS can carry out modification through modification or not, also can be the mixture of modified molecular screen and non-modified molecular sieve.
Described epoxidation reactor is fixed-bed reactor or slurry bed reactor.
Method of purifying propylene oxide provided by the invention, comprise: the reaction product from epoxidation reactor enters propylene separation tower and is separated, the tower top material obtained contain propylene, containing or containing propane, propylene oxide, methyl alcohol, containing or not moisture, materials at bottom of tower contains methyl alcohol, water, hydrogen peroxide and high boiling point by-products produced; Propylene separation column overhead material enters propylene stripping tower, and overhead gas contains propylene, contains or do not contain propane and a small amount of propylene oxide, enters in propylene oxide absorption tower to contact with absorption agent to remove propylene oxide, and then Returning reacting system recycles after compression; Propylene stripper bottoms material contain methyl alcohol, propylene oxide, containing or not moisture, further fractionation obtains highly purified product propylene.
In method provided by the invention, from the reaction product of Direct Epoxidation reactor, with weight, the propylene of the methyl alcohol usually containing 25%-80%, the water of 5%-45%, 1%-15%, 0%-5% propane, the propylene oxide of 5%-25%, the unreacted hydrogen peroxide of surplus and a small amount of high boiling by product.Reaction product enters propylene separation tower, described propylene separation tower has 5-60 theoretical stage, preferably 10-45 block theoretical stage, reaction product and propylene oxide absorption tower kettle material by being separated charging between the 1st piece of theoretical stage to the 20th piece of theoretical stage above tower top, preferably by charging between the 1st piece of theoretical stage to the 10th piece of theoretical stage above tower top.
The pressure of described propylene separation tower is 0.1MPa-0.5MPa, preferred 0.15MPa-0.3MPa; Reflux ratio is 0-3, preferred 0.1-1, and propylene separation tower can operate when not refluxing.The operational condition of preferred propylene separation tower, all to be discharged from tower top with propylene by propylene oxide, tower reactor obtains not containing the methyl alcohol of propylene oxide, unreacted hydrogen peroxide, water and high boiling point by-products produced.In the overhead product of described propylene separation tower, comprise all propylene oxide, propylene, contain or do not contain propane, and be no more than 50% of methyl alcohol total amount, usually 35% is no more than, preferably more than the methyl alcohol of 25%, containing or not moisture, also may containing noncondensable gases such as the oxygen generated by epoxidation reaction or peroxide decomposition produces, hydrogen, carbonic acid gas and nitrogen.
In method provided by the invention, preferably, reaction product is separated into overhead stream and tower base stream by propylene separation tower, and with weight, overhead stream contains 15%-50% propylene, 0%-10% propane, 10%-50% propylene oxide, 5%-50% methyl alcohol and 0-10% water.It is high boiling point by-products produced that tower base stream contains 30%-90% methyl alcohol, 20%-50% water, 0.1%-1% hydrogen peroxide and 0.1%-5%.
In method provided by the invention, the overhead stream of described propylene separation tower enters in propylene stripping tower, by the propylene that is dissolved in wherein and the non-condensable gas stripping such as propane and a small amount of oxygen, hydrogen, carbonic acid gas and nitrogen out.
Described propylene stripping tower has 5-30 block theoretical tray, preferred 10-20 block theoretical stage.The pressure of propylene stripping tower is 0.1MPa-0.4MPa, preferred 0.15MPa-0.3MPa.Stripping gas is out by the discharging of propylene stripper overhead, still containing a small amount of propylene oxide in overhead gas, therefore compressing and introducing in propylene oxide absorption tower before looping back reactive system again, absorption agent is utilized the propylene oxide absorption be contained in gas to be got off.
In method provided by the invention, described stripper overhead gas enters in propylene oxide absorption tower to contact with absorption agent and reclaims propylene oxide, and described propylene oxide absorption pressure tower is 0.1MPa-0.5MPa, preferred 0.15MPa-0.35Mpa.Only there is 5-15 block theoretical stage on absorption tower.Described absorption agent is selected from the mixture of one or more in water, alcohol, glycol and glycol ethers.Because the mixture of methyl alcohol and propylene oxide can when being recycled in preceding separation step without the need to when additional separation step, therefore absorption agent particular methanol.Absorption can directly be carried out at normal temperatures, also can carry out under low temperature.For ensureing assimilation effect, after the temperature of absorption agent and propylene stripper overhead product all can reduce to-5 DEG C-20 DEG C, enter propylene oxide absorption tower.Absorption tower tower top can be passed through compressor compresses through the gas that absorbs and is recycled in epoxidation reactor to the pressure of reactive system, propylene oxide absorption tower tower base stream comprises methyl alcohol, propylene, propylene oxide, containing or not moisture, return in propylene separation tower the propylene and propylene oxide that reclaim wherein.
In method provided by the invention, with weight, described propylene stripper bottoms stream contain the methyl alcohol of 10%-65%, 20%-60% propylene oxide, containing or not moisture, also may containing generate in epoxidization reaction process or in raw material with a small amount of aldehyde, ketone impurity.The method of existing known mode such as rectifying can be adopted to refine further and to obtain highly purified propylene oxide.
Preferably, introduce extractive distillation column from propylene stripper bottoms stream and extraction agent, under the condition of extracting rectifying, extracting rectifying column overhead obtains the extremely low product propylene of methanol content, obtains the mixture of methyl alcohol and extraction agent at the bottom of tower.
Described propylene stripper bottoms product and extraction agent can together with or add respectively in extractive distillation column, preferably, described propylene stripper bottoms product is introduced by the interlude of extractive distillation column, more preferably introduces at 2/3 place being equivalent to count from tower top theoretical stage sum downwards; Described extraction agent preferably joins in extractive distillation column at 1/3 place being equivalent to count from tower top theoretical stage sum downwards.
Described extraction agent is selected from the mixture of one or more in water, propylene glycol and the trimethyl carbinol.Because water can be separated with the mixture of methyl alcohol in downstream methanol purification step, without the need to extra extraction agent separating step, therefore preferred extraction agent is water.
The pressure 0.1-0.5MPa of extractive distillation column, preferred 0.1-0.3MPa, reflux ratio is 1-10.Because extracting rectifying pressure tower is lower, therefore tower top and the temperature at the bottom of tower lower, propylene oxide carries out being separated substantially do not have side reaction to occur in this tower.For reducing the content of methyl alcohol in overhead product, extractive distillation column needs enough theoretical stages.Preferred extractive distillation column has 20-50 theoretical tray.
When extraction agent is water, by the operation of Optimized Extraction rectifying tower, bottom product is substantially made up of methyl alcohol and extraction agent and not containing propylene oxide, preferably described extractive distillation column bottom product is delivered to methanol rectifying tower together with propylene separation tower bottom product and carry out Methanol Recovery.Methanol rectification tower overhead is generally the methyl alcohol that purity is greater than 95%, is the waste water containing high boiling point by-products produced and Trace Methanol at the bottom of tower.Overhead product methyl alcohol returns in direct cycloalkylation reactor as solvent cycle, the then discharger of waste water at the bottom of tower.For reducing the energy consumption of methanol rectifying tower, methanol fractionation system can adopt current industrial maturation and the double tower of widespread use, three towers or four tower rectification process.
Compared with prior art, method provided by the invention adopts low-temp low-pressure technique when carrying out product propylene and refining, and can guarantee reaction product oxypropylene separating effect, and improve the yield of propylene oxide; Adopt methyl alcohol as the absorption agent of propylene oxide absorption tower, the product after absorption returns propylene separation tower and reclaims propylene wherein and propylene oxide, reduce further the loss of propylene and propylene oxide; Extraction liquid at the bottom of extractive distillation column tower containing propylene oxide, can directly not delivered to methanol rectifying tower and be separated, decrease the loss of propylene oxide, reduce the process cost of device.
Method provided by the invention is further illustrated below in conjunction with accompanying drawing, below be only one embodiment of the present invention, can not limit the scope of the invention with this, namely every change of doing with the present patent application the scope of the claims and amendment, still belong to the scope that patent of the present invention contains.
Accompanying drawing is the schematic flow sheet of a kind of embodiment of method of purifying propylene oxide provided by the invention, uses titanium-silicon molecular sieve catalyst in epoxidation reactor, carries out the epoxidation reaction of propylene and hydrogen peroxide using methyl alcohol as solvent.First reaction product from epoxidation reactor enters in propylene separation tower 1 overhead stream be separated into containing propylene, propane, propylene oxide, methyl alcohol and a small amount of water through pipeline 6, and containing methyl alcohol, water, high boiling point by-products produced tower base stream.The working pressure of propylene separation tower 1 is 0.27MPa, and theoretical plate number is 25 pieces, and bottom temperature is 100 DEG C, and tower top is 0.1 ~ 0.5 without backflow or reflux ratio.
Propylene separation column overhead stream enters propylene stripping tower 2 through pipeline 8, propylene stripper overhead isolates the noncondensable gas such as propylene, propane and oxygen, hydrogen, carbonic acid gas, nitrogen containing a small amount of propylene oxide, obtains the material containing propylene oxide, first alcohol and water at the bottom of tower.Overhead gas enters propylene oxide absorption tower 3 through pipeline 10, to absorb the propylene oxide in gas through the methyl alcohol of pipeline 13 as absorption agent.Propylene oxide absorption tower tower base stream is made up of methyl alcohol, propylene oxide and propylene, returns in propylene separation tower 1 propylene and propylene oxide that reclaim wherein through pipeline 11.The theoretical plate number of described propylene oxide absorption tower 3 is 10, and working pressure is 0.25MPa.Propylene oxide absorption tower 3 overhead stream, primarily of propylene and propane composition, is drawn through pipeline 12, is turned back in epoxidation reactor after compressor compresses.
The materials at bottom of tower of propylene stripping tower 2 enters extractive distillation column 4 through pipeline 9, and extraction agent is that water enters in extractive distillation column 4 through pipeline 14 and carries out extracting rectifying, and extractive distillation column working pressure is 0.15MPa, and theoretical plate number is 40 pieces.Extractive distillation column 4 tower top obtains purity and is greater than 99%, is usually greater than the product propylene of 99.5%, is drawn by pipeline 16.Tower base stream contains first alcohol and water, draw through pipeline 15, it can be sent in methanol rectifying tower 5 together with the tower base stream of the propylene separation tower 1 through pipeline 7 and be separated, the overhead product containing more than 95% methyl alcohol is obtained through pipeline 18, methanol rectifying tower 5 overhead product can turn back in epoxidation reactor as solvent, wherein partial solvent also can be introduced in propylene oxide absorption tower 3 through pipeline 13, as the absorption agent absorbing propylene oxide.Bottom product is made up of water and high-boiling-point impurity, enters waste disposal plant process through pipeline 17 extraction.
Claims (16)
1. a method of purifying propylene oxide, it is characterized in that, reaction product from epoxidation reactor enters propylene separation tower, be separated the tower top material that obtains contain propylene, containing or containing propane, propylene oxide, methyl alcohol, containing or not moisture, materials at bottom of tower contains methyl alcohol, water, hydrogen peroxide and high boiling point by-products produced; Propylene separation column overhead material enters propylene stripping tower, stripping removes propylene, propane wherein, overhead gas after stripping contains propylene, contains or does not contain propane, a small amount of propylene oxide, enter in propylene oxide absorption tower to contact with absorption agent and remove propylene oxide, then Returning reacting system recycles after compression; Propylene stripper bottoms material contain propylene oxide, methyl alcohol, containing or not moisture, further fractionation obtains highly purified product propylene; The pressure of described propylene separation tower is 0.1MPa-0.5MPa, and reflux ratio is 0-3, and tower top temperature is 60 DEG C-90 DEG C, and column bottom temperature is 80 DEG C-110 DEG C.
2. according to the method for claim 1, it is characterized in that, the pressure of described propylene separation tower is 0.15MPa-0.3MPa, and reflux ratio is 0.1-1, and tower top temperature is 70 DEG C-85 DEG C, and column bottom temperature is 85 DEG C-100 DEG C.
3. according to the method for claim 1 or 2, it is characterized in that, with weight, described propylene separation column overhead material contains the water of the propylene of 15%-50%, the propane of 0-10%, the propylene oxide of 10%-50%, the methyl alcohol of 5%-50% and 0-10%; Described propylene separation tower materials at bottom of tower contains the high boiling point by-products produced of the methyl alcohol of 30%-90%, the water of 20%-50%, the hydrogen peroxide of 0.1%-1% and 0.1%-5%; Wherein, described propylene separation column overhead material, materials at bottom of tower component summation are 100%.
4. according to the method for claim 1, it is characterized in that, described propylene pressure of stripping tower is 0.1MPa-0.4MPa, and bottom temperature is 55 DEG C-80 DEG C.
5. according to the method for claim 4, it is characterized in that, described propylene pressure of stripping tower is 0.15MPa-0.3MPa.
6. according to the method for claim 1,4 or 5, it is characterized in that, described propylene stripper bottoms stream contains the methyl alcohol of 10%-65%, the propylene oxide of 20%-60%, and remaining is high boiling point by-products produced, containing or not moisture.
7. according to the method for claim 1, it is characterized in that, the pressure of described propylene oxide absorption tower is 0.1MPa-0.5MPa.
8. according to the method for claim 7, it is characterized in that, described propylene oxide absorption pressure tower is 0.15MPa-0.35Mpa.
9. according to the method for claim 1,7 or 8, it is characterized in that, the absorption agent in described propylene oxide absorption tower is selected from the mixture of one or more in water, alcohol, glycol and glycol ethers.
10. according to the method for claim 9, it is characterized in that, described absorption agent is methyl alcohol.
11. according to the method for claim 1, it is characterized in that, described propylene stripper bottoms stream and extraction agent enter extractive distillation column, under extracting rectifying condition, extracting rectifying column overhead obtains the extremely low product propylene of methanol content, obtains the mixture of methyl alcohol and extraction agent at the bottom of extractive distillation column tower.
12. according to the method for claim 11, and it is characterized in that, the pressure of described extractive distillation column is 0.1-0.5MPa, and reflux ratio is 1-10.
13. according to the method for claim 12, and it is characterized in that, the pressure of described extractive distillation column is 0.1-0.3MPa.
14. according to the method for claim 11, and it is characterized in that, described extraction agent is selected from the mixture of one or more in water, propylene glycol and the trimethyl carbinol.
15. according to the method for claim 14, and it is characterized in that, described extraction agent is water.
16. 1 kinds of Direct Epoxidations prepare propylene oxide and product separation method, it is characterized in that, comprising:
(1) hydrogen peroxide and propylene mixed dissolution in organic solvent, contact with titanium-silicon molecular sieve catalyst in epoxidation reactor and carry out epoxidation reaction, obtain the reaction product containing propylene oxide, described reaction product comprises propane, propylene, propylene oxide, organic solvent, water and high boiling point by-products produced on a small quantity;
(2) reaction product from epoxidation reactor enters the separation of propylene separation tower, the tower top material obtained contain propylene, containing or containing propane, propylene oxide, methyl alcohol, containing or not moisture, materials at bottom of tower contains methyl alcohol, water, hydrogen peroxide and high boiling point by-products produced; Propylene separation column overhead material enters propylene stripping tower, overhead gas contain propylene, containing or not containing propane, a small amount of propylene oxide, enter in propylene oxide absorption tower to contact with absorption agent and remove propylene oxide Posterior circle and use; Propylene stripper bottoms material contain methyl alcohol, propylene oxide, containing or not moisture, further fractionation obtains highly purified product propylene.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110434194.2A CN103172596B (en) | 2011-12-22 | 2011-12-22 | Propylene oxide refining method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110434194.2A CN103172596B (en) | 2011-12-22 | 2011-12-22 | Propylene oxide refining method |
Publications (2)
| Publication Number | Publication Date |
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| CN103172596A CN103172596A (en) | 2013-06-26 |
| CN103172596B true CN103172596B (en) | 2015-02-25 |
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| CN104557784B (en) * | 2013-10-29 | 2017-09-29 | 中国石油化工股份有限公司 | A kind of method for producing expoxy propane |
| CN106518810B (en) * | 2015-09-15 | 2020-09-04 | 中国石油化工股份有限公司 | Method for purifying propylene oxide |
| TWI707847B (en) * | 2015-11-26 | 2020-10-21 | 德商贏創運營有限公司 | Process for the epoxidation of propene |
| CN105399606B (en) * | 2015-12-18 | 2018-02-02 | 山东蓝星东大化工有限责任公司 | Technique for recovering propylene in expoxy propane subtractive process |
| CN113968831B (en) * | 2020-07-24 | 2024-02-09 | 中国石油化工股份有限公司 | Propylene oxide refining method, propylene oxide stream separation method, epoxidation reaction product separation method and propylene epoxidation method |
| CN113512013B (en) * | 2021-06-30 | 2023-09-05 | 中国石油化工股份有限公司 | System and method for preparing propylene oxide from large-scale industrial methanol |
| CN116003348A (en) * | 2021-10-22 | 2023-04-25 | 中国石油化工股份有限公司 | Method for treating propylene oxide and propylene containing material, application and device thereof and method for recycling propylene oxide tail gas |
| CN115073397B (en) * | 2022-05-12 | 2024-01-26 | 博大东方新型化工(吉林)有限公司 | Novel epoxypropane dehydration process |
| CN115745915B (en) * | 2022-11-03 | 2024-07-26 | 中国五环工程有限公司 | Energy-saving process for producing epoxypropane by HPPO method reaction rectification |
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| CN86105706A (en) * | 1985-07-03 | 1987-02-25 | 日本触媒化学工业株式会社 | Method for purification ethylene oxide |
| US5849938A (en) * | 1997-09-02 | 1998-12-15 | Arco Chemical Technology, L.P. | Separation of methanol and propylene oxide from a reaction mixture |
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