CN103172595A - Method for refining propylene oxide from products of direct epoxidation reaction - Google Patents
Method for refining propylene oxide from products of direct epoxidation reaction Download PDFInfo
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Abstract
The invention provides a method for refining propylene oxide from products of direct epoxidation reaction. The method is characterized by comprising the steps that reaction products from an epoxidation reactor 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 enter a propylene oxide absorption column to come into contact with an absorbent to remove propylene oxide out of the column top materials, and the gas without propylene oxide returns to the epoxidation reactor after being compressed; and column bottom materials from the propylene oxide absorption column return to the propylene separating column and the column bottom materials from the propylene separating column contain methanol, propylene oxide, water and few high-boiling-point byproducts 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 through direct epoxidation. The methods 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 the method made from extra care propylene oxide in the reaction product of a kind of hydrogen peroxide and propylene reaction preparation 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 also the important source material of nonionogenic tenside, oil field demulsifier, farm chemical emulgent etc. mainly for the production of polyethers, propylene glycol, propylene glycol etc.The derivative of propylene oxide also is widely used in the industries such as food, tobacco, agricultural chemicals and makeup.Nearly hundred kinds of the derived product of having produced are the important source material of fine chemical product.
Synthesis of Propylene Oxide mainly contains chlorohydrination, conjugated oxidation and direct oxidation method, and all there are the defectives such as cost is high, pollution is large in front two kinds of production methods.The main problem of chlorohydrination is serious to equipment corrosion, and produces waste water, the waste residue of a large amount of organic chlorides in producing; Conjugated oxidation has long flow path, investment is large, by product is many, is subjected to the problems such as oil crisis, energy shortage, the restriction of byproduct outlet; The 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 characteristics such as environmental friendliness, so titanium molecular sieve catalysis epoxidation of propylene synthesizing epoxypropane is considered to the development trend of propylene oxide synthetic technology.
Generally adopt a large amount of methyl alcohol as solvent in the Direct Epoxidation technique of propylene and hydrogen peroxide, excessive propylene is dissolved in methanol solution reacts with hydrogen peroxide, thereby guarantee the transformation efficiency of higher hydrogen peroxide and the selectivity of propylene oxide.Although the reaction of the Direct Epoxidation of propylene and hydrogen peroxide has very high selectivity and transformation efficiency, but there are a large amount of solvents, water and unreacted propylene in reaction process, generate a small amount of but the impurity such as miscellaneous aldehyde, ether, alcohol, ketone, make the refining very difficult of propylene oxide.Simultaneously, in the product rectifying, the propylene oxide impurity such as generating ether that can react with other material of water and hydroxyl at higher temperature reduced the yield of propylene oxide, so the process for refining of propylene oxide is the key of direct oxidation method technique success or not.
Usually the mixture that contains a large amount of solvents, unreacting propylene, propylene oxide, water and other impurity that obtains in the Direct Epoxidation reaction first distills through the first step, reaction product is separated into the tower top material that contains propylene oxide, propylene and propane and oxygen, and the materials at bottom of tower that contains solvent, water and high-boiling-point impurity, overhead product can further separate in second distilation steps, tower top obtains containing the light constituent of propylene, propane, be crude propene oxide at the bottom of tower, as US5599955, US6881853.Perhaps the tower top material of the first step distillation is removed the light constituents such as propylene through partial condensation and stripping, then separate through the mode of extracting rectifying and obtain crude propene oxide (＞99.5%) and methanol aqueous solution, by the product propylene that the extracting rectifying column overhead obtains making with extra care, be extraction agent, methyl alcohol, water and other impurity at the bottom of tower.For example CN1398262A, US6024840, EP2168953.Propylene oxide is only made with extra care with the mode of extracting rectifying, can't effectively remove wherein acetaldehyde, acetone and methyl-formiate.
In the product separation process of Direct Epoxidation reaction, for suppress propylene oxide at higher temperature with the reaction of water and hydroxyl material, existing separating technology substantially all adopts the mode of in first distillation tower after reactor, propylene oxide being discharged with propylene from tower top, shortens the residence time of propylene oxide in tower as far as possible and reduces service temperature.In first distillation tower overhead stream except propylene oxide and propylene, also contain the impurity such as some solvent and/or a small amount of water and acetaldehyde, therefore overhead stream also needs to enter the propylene stripping tower again and makes propylene and propylene oxide and separated from solvent, the propylene that propylene stripping tower tower top is discharged after partial condensation needs to remove the propylene oxide of wherein carrying secretly in compression as last, and at the bottom of tower, discharge ring Ethylene Oxide and solvent need carry out extracting rectifying and carry out further making with extra care just obtaining product.The flow process that propylene oxide is made with extra care is long, energy consumption is higher.
Summary of the invention
One of the technical problem to be solved in the present invention be to provide a kind of propylene oxide yield losses little, simplify separation process and reduce the method for purification propylene oxide from the Direct Epoxidation reaction product of plant energy consumption.
Two of the technical problem that will solve of the present invention is to provide a kind ofly uses the direct oxidation of titanium-silicon molecular sieve catalyst to prepare propylene oxide and reaction product separation method.
A kind of from the Direct Epoxidation reaction product method of purification propylene oxide, comprising:
Entering the propylene separation tower from the reaction product of epoxidation reactor separates and obtains overhead stream and tower base stream, described overhead stream contains propylene, propylene oxide, methyl alcohol, contain or do not contain propane, contain or not moisture, enter the propylene oxide absorption tower, contact the propylene oxide that removes wherein with absorption agent, the gas that removes propylene oxide returns in epoxidation reactor after compression; Propylene oxide absorption tower tower base stream is back to the propylene separation tower, and propylene separation tower tower base stream contains methyl alcohol, propylene oxide, water and high boiling point by-products produced on a small quantity, and further fractionation obtains highly purified product propylene.
A kind of direct oxidation prepares propylene oxide and product separation method, comprising:
(1) hydrogen peroxide and propylene mixed dissolution in methyl alcohol, contact with titanium-silicon molecular sieve catalyst in epoxidation reactor and carry out epoxidation reaction, obtain containing the reaction product of propylene oxide, described reaction product comprise propylene, propylene oxide, methyl alcohol, water and on a small quantity high boiling point by-products produced, contain or do not contain propane;
(2) entering the propylene separation tower from the reaction product of epoxidation reactor separates and obtains overhead stream and tower base stream, described overhead stream contains propylene propylene oxide, methyl alcohol, contain or do not contain propane, contain or not moisture, enter the propylene oxide absorption tower, contact the propylene oxide that removes wherein with absorption agent, the gas that removes propylene oxide returns in epoxidation reactor after compression; Propylene oxide absorption tower tower base stream is back to the propylene separation tower, and propylene separation tower tower base stream contains methyl alcohol, propylene oxide, water and high boiling point by-products produced on a small quantity, and further fractionation obtains highly purified product propylene.
Provided by the invention a kind of from the Direct Epoxidation reaction product method of purification propylene oxide and the beneficial effect that direct oxidation prepares propylene oxide and product separation method be:
Suitable pressure and column bottom temperature are adopted in extraction at the bottom of method provided by the invention makes most of propylene oxide by propylene separation tower tower when the separating-purifying product propylene simultaneously, suppress the side reaction of propylene oxide and reduce the yield losses of propylene oxide; Only extraction part of propylene separation column overhead propylene oxide, thus keep suitable overhead condensation temperature and need not to adopt the higher refrigerant of process cost to carry out cooling to overhead product.Propylene oxide separating and purifying method in the present invention need not to adopt the propylene stripping tower to carry out stripping to the propylene in propylene oxide, only need adopt an absorption tower to absorb processing to the propylene oxide in propylene, thereby simplified the separation process of propylene oxide, saved facility investment.
Description of drawings
Accompanying drawing 1 is the schematic flow sheet of a kind of embodiment of method provided by the invention;
Accompanying drawing 2 is the schematic flow sheet of the another kind of embodiment of method provided by the invention.
Embodiment
Provided by the invention from the Direct Epoxidation reaction product method of purification propylene oxide, and specifically enforcement like this of the method that comprises the oxyethane preparation of Direct Epoxidation reactions steps and separation and purification:
A kind of from the Direct Epoxidation reaction product method of purification propylene oxide, comprise: enter the propylene separation tower from the reaction product of epoxidation reactor and separate and obtain overhead stream and tower base stream, described overhead stream contains propylene, propylene oxide, methyl alcohol, contain or do not contain propane, contain or not moisture, enter the propylene oxide absorption tower, contact the propylene oxide that removes wherein with absorption agent, the gas that removes propylene oxide returns in epoxidation reactor after compression; Propylene oxide absorption tower tower base stream is back to the propylene separation tower, and propylene separation tower tower base stream contains methyl alcohol, propylene oxide, water and high boiling point by-products produced on a small quantity, and 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, be preferably 0.15MPa-0.3MPa, reflux ratio is 0-1, and tower top temperature is 30 ℃-50 ℃, is preferably 35 ℃-45 ℃, and column bottom temperature is 80 ℃-110 ℃, is preferably 85 ℃-100 ℃.
In method provided by the invention, in weight percentage, the logistics of described propylene separation column overhead contains the propane of 15%-90% propylene, 0%-10%, the propylene oxide of 1%-20%, the methyl alcohol of 30%-80% and the water of 0-5%; Tower base stream contains the water of 30%-80% methyl alcohol, 10%-40%, the propylene oxide of 5%-20% and the high-boiling-point impurity of 0.1%-5%.
In method provided by the invention, the pressure of described propylene oxide absorption tower is 0.1MPa-0.5MPa, be preferably 0.15MPa-0.35Mpa.
In method provided by the invention, the absorption agent in described propylene oxide absorption tower is selected from one or more the mixture in water, alcohol, two pure and mild glycol ethers, is preferably methyl alcohol.
In method provided by the invention, described propylene oxide absorption tower tower base stream and extraction agent enter extractive distillation column, under the extracting rectifying condition, the 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 the extractive distillation column tower.
The pressure of described extractive distillation column is 0.1-0.5MPa, is preferably 0.1-0.3MPa, and reflux ratio is 1-10.
Described extraction agent is selected from one or more the mixture in water, propylene glycol and the trimethyl carbinol, is preferably water.
A kind of Direct Epoxidation prepares propylene oxide and product separation method, comprising:
(1) hydrogen peroxide and propylene mixed dissolution in methyl alcohol, contact with titanium-silicon molecular sieve catalyst in epoxidation reactor and carry out epoxidation reaction, obtain containing the reaction product of propylene oxide, described reaction product comprises propylene, propylene oxide, methyl alcohol, water, high boiling point by-products produced on a small quantity, contains or do not contain propane;
(2) entering the propylene separation tower from the reaction product of epoxidation reactor separates and obtains overhead stream and tower base stream, described overhead stream contains propylene, propylene oxide, methyl alcohol, contain or do not contain propane, contain or not moisture, enter the propylene oxide absorption tower, contact the propylene oxide that removes wherein with absorption agent, the gas that removes propylene oxide returns in epoxidation reactor after compression; Propylene oxide absorption tower tower base stream is back to the propylene separation tower, and propylene separation tower tower base stream contains methyl alcohol, propylene oxide, water and high boiling point by-products produced on a small quantity, and further fractionation obtains highly purified product propylene.
In method provided by the invention, the Direct Epoxidation reaction of described use titanium-silicon molecular sieve catalyst comprises, hydrogen peroxide and propylene be mixed dissolution in organic solvent, particular methanol solvent, under titanium-silicon molecular sieve catalyst exists, in the organic solvent environment, the hydrogen peroxide oxidation propylene generates propylene oxide and water, and generates the by products such as propylene glycol, propylene glycol monomethyl ether, acetaldehyde, acetone, methyl-formiate.Obtain containing the reaction product of propylene oxide, described reaction product comprises propylene, propylene oxide, methyl alcohol, water and high boiling point by-products produced on a small quantity, contains or do not contain propane.
In method provided by the invention, the 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.The preferred methyl alcohol that uses is as solvent.In solvent, the weight percentage of methyl alcohol is 5%-100%, preferred 50%-100%, and more preferably 90%-100%, can contain a small amount of impurity such as water etc.Described hydrogen peroxide raw material uses with the form of the aqueous solution of the hydrogen peroxide that contains 5%-75%, the preferred hydrogen peroxide product that contains 20%-55% that uses by anthraquinone preparation.Can contain the propane of 0%-15% in raw material propylene.
In method provided by the invention, the operational condition of described epoxidation reactor is: temperature is 10 ℃-80 ℃, preferred 25 ℃-55 ℃, pressure is 1.5MPa-5.0MPa, use excessive propylene and control solution the pH value so that the transformation efficiency of hydrogen peroxide reach more than 90%.For guaranteeing that propylene and hydrogen peroxide dissolve mutually under reaction pressure, the usage quantity of solvent makes the hydrogen peroxide of every mole that the solvent of 1-15 mole be arranged through preferred.
Described catalyzer is HTS powder or HTS and carrier-bound titanium-silicon molecular sieve catalyst, and wherein HTS can or not carried out modification through modification, can be the mixture of modified molecular screen and non-modified molecular screen yet.Described epoxidation reactor can be fixed-bed reactor or slurry bed reactor.
In method provided by the invention, reaction product from epoxidation reactor, in weight percentage, usually contain the methyl alcohol of 25%-80%, the water of 5%-45%, propylene, 0%-5% propane, the propylene oxide of 5%-25%, unreacted hydrogen peroxide and a small amount of high boiling by product of 1%-15%.Reaction product enters the separation of propylene separation tower and obtains overhead stream and tower base stream, described overhead stream contains propylene, propylene oxide, methyl alcohol, contain or do not contain propane, contain or not moisture, enter the propylene oxide absorption tower, contact the propylene oxide that removes wherein with absorption agent, the gas that removes propylene oxide returns in epoxidation reactor after compression; Propylene oxide absorption tower tower base stream is back to the propylene separation tower, and propylene separation tower tower base stream contains methyl alcohol, propylene oxide, water and high boiling point by-products produced on a small quantity, and further fractionation obtains highly purified product propylene.
In method provided by the invention, described propylene separation tower has 5-45 theoretical stage, preferred 10-45 piece theoretical tray.The pressure of described propylene separation tower is 0.1MPa-0.5MPa, preferred 0.15MPa-0.3MPa; Reflux ratio is 0-1, and the propylene separation tower can be in the situation that do not have backflow to operate.The operational condition of propylene separation tower is through preferred design, in order to most propylene oxide is retained in bottom product, and the temperature at the bottom of control tower is with the side reaction of reduce propylene oxide.Control the content of tower top propylene oxide in products and solvent, thereby keep suitable overhead condensation temperature and need not to adopt the higher refrigerant of process cost to carry out cooling to overhead product.In the operating process of described propylene separation tower, all propylene and propane are contained in overhead product, be no more than 30%, usually be no more than 20%, preferably being no more than 15% propylene oxide is contained in overhead product, and surpass 90%, usually surpass 95%, preferably surpass 99% water and be contained in bottom product.
In method provided by the invention, preferably, reaction product is separated into overhead stream and tower base stream by the propylene separation tower, and in weight percentage, overhead stream contains the propane of 15%-90% propylene, 0%-10%, the propylene oxide of 1%-20%, the methyl alcohol of 30%-80% and the water of 0-5%.Tower base stream contains the water of 30%-80% methyl alcohol, 10%-40%, the propylene oxide of 5%-20% and the high-boiling-point impurity of 0.1%-5%.
In method provided by the invention, the overhead stream of described propylene separation tower enters in the propylene oxide absorption tower, contacts with absorption agent to reclaim propylene oxide, and described propylene oxide absorption pressure tower is 0.1MPa-0.5MPa, preferred 0.15MPa-0.35Mpa.Only there is 5-15 piece theoretical stage on the absorption tower.Described absorption agent can be the organic solvent that uses in reaction, particular methanol.Absorption can directly be carried out at normal temperatures, also can carry out under low temperature.The overhead product that absorption agent and propylene separation tower come can be lowered the temperature through refrigerant before entering the absorption tower, also can directly absorb at normal temperatures.For guaranteeing assimilation effect, the overhead product temperature that preferred absorption agent and propylene separation tower come can be reduced to-5 ℃-20 ℃.The absorption tower tower top through the gas that absorption can be compressed to the pressure of reactive moieties and be recycled in epoxidation reactor.The absorbing tower bottom product is back to propylene separation tower recovery propylene oxide wherein.
In method provided by the invention, described propylene separation tower tower base stream contains the high boiling point by-products produced of the propylene oxide of water, 5%-20% of 30%-80% methyl alcohol, 10%-40% and 0.1%-5%.Can adopt for example further refining highly purified propylene oxide that obtains of method of rectifying of existing known mode.Methyl alcohol wherein is recycled in epoxidation reaction after refining.
Preferably, propylene separation tower tower base stream and extraction agent are introduced extractive distillation column, and under the condition of extracting rectifying, the 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 separation tower bottom product and extraction agent can be together or are added respectively in extractive distillation column, preferably, described propylene separation tower bottom product is introduced by the interlude of extractive distillation column, more preferably in the 2/3 place introducing that is equivalent to count from tower top the theoretical stage sum downwards; Described extraction agent preferably is being equivalent in 1/3 place that tower top is counted the theoretical stage sum downwards joins extractive distillation column.
Described extraction agent is selected from one or more the mixture in water, propylene glycol and the trimethyl carbinol.Need not extra extraction agent separating step because the mixture of water and methyl alcohol can separate in the refining methanol step of downstream, 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 the extracting rectifying pressure tower is lower, so the temperature at the bottom of tower top and tower is lower, and propylene oxide separates in this tower does not have side reaction to occur substantially.For reducing the content of methyl alcohol, water and other impurity in overhead product, extractive distillation column needs enough theoretical stages.Preferred extractive distillation column has 20-50 theoretical tray.
Operation by the Optimized Extraction rectifying tower, bottom product substantially is comprised of methyl alcohol and extraction agent and does not contain propylene oxide, when extraction agent is water, 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.The methanol rectifying tower overhead product is generally purity greater than 95% methyl alcohol, is the waste water that contains high-boiling-point impurity and Trace Methanol at the bottom of tower.Overhead product methyl alcohol is as in solvent cycle winding alkylation reactors, waste water discharger at the bottom of tower.For reducing the energy consumption of methanol rectifying tower, methanol fractionation system can adopt double tower, three towers or the four tower rectification process of present industrial maturation and widespread use.
In another embodiment, the product that obtains at the bottom of the propylene separation tower tower can first carry out rectifying by a common rectifying tower, obtains the mixture of the lower propylene oxide of relative concentration and methyl alcohol, water from tower top.The concentration of the propylene oxide that usually obtains is 90%-99%, preferred 92%-96%.Overhead product obtains product propylene through the mode of above-mentioned extracting rectifying again.Bottom product is the mixture of first alcohol and water, through the methanol rectification step remove wherein water and other impurity after with methanol loop in epoxidation reaction.
Method provided by the invention carry out product propylene make most of propylene oxide by propylene separation tower tower when refining at the bottom of extraction, adopt simultaneously suitable pressure and column bottom temperature, suppress the side reaction of propylene oxide and reduce the yield losses of propylene oxide; Only extraction part of propylene separation column overhead propylene oxide, thus keep suitable overhead condensation temperature and need not to adopt the higher refrigerant of process cost to carry out cooling to overhead product.Process for refining in the present invention need not to adopt the propylene stripping tower to carry out stripping to the propylene in propylene oxide, only need adopt an absorption tower to absorb processing to the propylene oxide in propylene, thereby simplify the separation process of propylene oxide, has saved facility investment.
Further illustrate method provided by the invention below in conjunction with Figure of description, be only below one embodiment of the present invention, but can not therefore limit the scope of the invention, i.e. every variation and modification of being done with the application's claim scope still belongs to the scope that the present invention is contained.
Accompanying drawing 1 is the schematic flow sheet of a kind of embodiment of method provided by the invention, uses titanium-silicon molecular sieve catalyst and methyl alcohol to carry out the epoxidation reaction of propylene and hydrogen peroxide as solvent in epoxidation reactor.At first enter in propylene separation tower T1 1 from the reaction product of epoxidation reactor through pipeline 1 and be separated into overhead stream and tower base stream, the overhead stream of drawing through pipeline 2 contains propylene, propylene oxide, methyl alcohol, contain or do not contain propane, contain or not moisture, and the tower base stream of drawing through pipeline 3 contains methyl alcohol, propylene oxide, water and high boiling point by-products produced.The working pressure of propylene separation tower T1 is 0.22MPa, and theoretical plate number is 25, and the tower reactor temperature is 91 ℃, and the trim the top of column ratio is 0.1～0.5.Propylene separation tower T1 overhead stream enters propylene oxide absorption tower T2 through pipeline 2, absorbs wherein propylene oxide through the methyl alcohol of pipeline 10 as absorption agent.Propylene oxide absorption tower T2 tower base stream is comprised of methyl alcohol, propylene oxide and propylene, returns to through pipeline 4 propylene and the propylene oxide that reclaims in propylene separation tower T1 wherein.The theoretical plate number of described propylene oxide absorption tower T2 is 10, and working pressure is 0.17MPa.Propylene oxide absorption tower T2 overhead stream is mainly by propylene, or propylene and propane composition, draws through pipeline 5, turns back in epoxidation reactor through after compressor compresses.
Propylene separation tower T1 tower base stream is by methyl alcohol, water and propylene oxide and high boiling point by-products producedly form and do not contained propylene and propane, enter extractive distillation column T3 through pipeline 3, enter extractive distillation column T3 as extraction agent through pipeline 11 with water, carry out extracting rectifying, the extractive distillation column working pressure is 0.15MPa, and theoretical plate number is 40.Tower top obtains purity greater than 98%, usually greater than 99.5% product propylene, is drawn by pipeline 7.Tower base stream is drawn through pipeline 6, contains the first alcohol and water, sends into to be separated into the first alcohol and water in methanol rectifying tower T4, draws the overhead product that contains 95% above methyl alcohol through pipeline 9, draws the bottom product that is comprised of water and high-boiling-point impurity through pipeline 8.Methanol rectifying tower T4 overhead product can be used as solvent and turns back in epoxidation reactor, and bottom product was entered waste disposal plant and processed by water and high boiling point by-products produced the composition.
In the preferred implementation of Fig. 1, method of the present invention also has following advantage: can realize the separation of propylene with less reflux ratio in than prior art in propylene separation tower T1, thereby save running cost; In the propylene separation tower most of propylene oxide by tower at the bottom of extraction, adopt simultaneously suitable pressure and column bottom temperature, suppress the side reaction of propylene oxide and reduce the yield losses of propylene oxide; Non-condensable gas and the part propylene oxide such as propylene separation column overhead extraction propylene and propane, thus keep suitable overhead condensation temperature and need not to adopt the higher refrigerant of process cost to carry out cooling to overhead product.Compared with prior art, propylene separation tower T1 overhead stream only need absorb the propylene oxide that just can remove in propylene, need not to adopt propylene stripping tower separation of propylene and propylene oxide, thereby has saved cost of equipment.
Accompanying drawing 2 is the schematic flow sheet of the another kind of embodiment of method provided by the invention, in embodiment as Fig. 2, the tower base stream of propylene separation tower T1 is introduced in a common rectifying tower T5 through pipeline 3 and separates, separating the crude propene oxide that contains a small amount of methyl alcohol that obtains draws through pipeline 7, wherein the concentration of propylene oxide is 90%-99%, preferred 92%-96%.Separating the bottom product that obtains is the mixture of first alcohol and water, draws through pipeline 6.Overhead product enters extractive distillation column T3 through pipeline 7 again and carries out extracting rectifying, and water is introduced extractive distillation column T3 as extraction agent through pipeline 11, obtains concentration and draws through pipeline 12 in the smart product propylene more than 99.5%.Bottom product through pipeline 13 with send in methanol rectifying tower T4 together with the common rectifying tower T5 of pipeline 6 bottom product, the discharging of methanol rectifying tower T4 tower top is methyl alcohol, is recycled in epoxidation reactor through pipeline 9.Be water and other impurity at the bottom of methanol rectifying tower T4 tower, introduce in waste disposal plant through pipeline 8 and process.This embodiment can significantly reduce the consumption of extraction agent, and has reduced the process cost of device.
Claims (14)
1. the method for a purification propylene oxide from the Direct Epoxidation reaction product, it is characterized in that, comprise: enter the propylene separation tower from the reaction product of epoxidation reactor and separate and obtain overhead stream and tower base stream, described overhead stream contains propylene, propylene oxide, methyl alcohol, contain or do not contain propane, contain or not moisture, enter the propylene oxide absorption tower, contact the propylene oxide that removes wherein with absorption agent, the gas that removes propylene oxide returns in epoxidation reactor after compression; Propylene oxide absorption tower tower base stream is back to the propylene separation tower, and propylene separation tower tower base stream contains methyl alcohol, propylene oxide, water and high boiling point by-products produced on a small quantity, and further fractionation obtains highly purified product propylene.
2. according to the method for claim 1, it is characterized in that, the pressure of described propylene separation tower is 0.1MPa-0.5MPa, and reflux ratio is 0-1, and tower top temperature is 30 ℃-50 ℃, and column bottom temperature is 80 ℃-110 ℃.
3. according to the method for claim 2, it is characterized in that, the pressure of described propylene separation tower is 0.15MPa-0.3MPa, and tower top temperature is 35 ℃-45 ℃, and column bottom temperature is 85 ℃-100 ℃.
4. according to claim 1,2 or 3 method, it is characterized in that, in weight percentage, the logistics of described propylene separation column overhead contains the propane of 15%-90% propylene, 0%-10%, the propylene oxide of 1%-20%, the methyl alcohol of 30%-80% and the water of 0-5%; Tower base stream contains the water of 30%-80% methyl alcohol, 10%-40%, the propylene oxide of 5%-20% and the high-boiling-point impurity of 0.1%-5%.
5. 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.
6. according to the method for claim 5, it is characterized in that, described propylene oxide absorption pressure tower is 0.15MPa-0.35Mpa.
7. according to claim 1,5 or 6 method, it is characterized in that, the absorption agent in described propylene oxide absorption tower is selected from one or more the mixture in water, alcohol, two pure and mild glycol ethers.
8. according to the method for claim 7, it is characterized in that, the absorption agent in described propylene oxide absorption tower is methyl alcohol.
9. according to the method for claim 1, it is characterized in that, described propylene oxide absorption tower tower base stream and extraction agent enter extractive distillation column, under the extracting rectifying condition, the 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 the extractive distillation column tower.
10. according to the method for claim 9, it is characterized in that, the pressure of described extractive distillation column is 0.1-0.5MPa, and reflux ratio is 1-10.
11. the method according to claim 10 is characterized in that, the pressure of described extractive distillation column is 0.1-0.3MPa.
12. the method according to claim 9 is characterized in that, described extraction agent is selected from one or more the mixture in water, propylene glycol and the trimethyl carbinol.
13. the method according to claim 12 is characterized in that, described extraction agent is water.
14. a Direct Epoxidation prepares propylene oxide and product separation method, it is characterized in that, comprising:
(1) hydrogen peroxide and propylene mixed dissolution in methyl alcohol, contact with titanium-silicon molecular sieve catalyst in epoxidation reactor and carry out epoxidation reaction, obtain containing the reaction product of propylene oxide, described reaction product comprises propylene, propylene oxide, methyl alcohol, water, high boiling point by-products produced on a small quantity, contains or do not contain propane;
(2) entering the propylene separation tower from the reaction product of epoxidation reactor separates and obtains overhead stream and tower base stream, described overhead stream contains propylene, propylene oxide, methyl alcohol, contain or do not contain propane, contain or not moisture, enter the propylene oxide absorption tower, contact the propylene oxide that removes wherein with absorption agent, the gas that removes propylene oxide returns in epoxidation reactor after compression; Propylene oxide absorption tower tower base stream is back to the propylene separation tower, and propylene separation tower tower base stream contains methyl alcohol, propylene oxide, water and high boiling point by-products produced on a small quantity, and further fractionation obtains highly purified product propylene.
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Cited By (3)
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| CN109020926A (en) * | 2017-12-19 | 2018-12-18 | 华东理工大学 | A method of it separated from propylene gas-phase epoxidation product, purify propylene oxide |
| CN113149934A (en) * | 2015-11-26 | 2021-07-23 | 赢创运营有限公司 | Equipment for producing propylene oxide |
| CN113968830A (en) * | 2020-07-24 | 2022-01-25 | 中国石油化工股份有限公司 | Method for separating propylene oxide stream, method for separating epoxidation reaction product, and method for epoxidizing propylene |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113149934A (en) * | 2015-11-26 | 2021-07-23 | 赢创运营有限公司 | Equipment for producing propylene oxide |
| CN109020926A (en) * | 2017-12-19 | 2018-12-18 | 华东理工大学 | A method of it separated from propylene gas-phase epoxidation product, purify propylene oxide |
| CN113968830A (en) * | 2020-07-24 | 2022-01-25 | 中国石油化工股份有限公司 | Method for separating propylene oxide stream, method for separating epoxidation reaction product, and method for epoxidizing propylene |
| CN113968830B (en) * | 2020-07-24 | 2024-01-09 | 中国石油化工股份有限公司 | Separation method of epoxypropane stream and separation method of epoxidation reaction product and propylene epoxidation method |
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| CN103172595B (en) | 2015-03-18 |
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