Refining method of polymer-grade m-pentadiene

Abstract

The invention discloses a method for refining polymer-grade m-pentadiene. The method comprises the following steps: carrying out selective hydrogenation reaction on a crude m-pentadiene material to remove alkyne so as to obtain an alkyne-removed m-pentadiene intermediate material; mixing the deacetylated m-pentadiene intermediate material with cyclic ketone, alcohol and organic alkali, and carrying out reactive distillation to remove cyclopentadiene so as to obtain decyclized m-pentadiene; and refining and purifying the decyclized m-pentadiene through water washing and extractive distillation to obtain the decyclized m-pentadiene. The obtained polymer-grade pentadiene product is high in purity, the content of impurity cyclopentadiene in the polymer-grade pentadiene product is lower than 1ppm, and the content of impurity alkyne in the polymer-grade pentadiene product is lower than 20ppm.

Description

TECHNICAL FIELD

[0001] The application relates to a method for purifying piperylene, in particular to a method for refining polymer-grade piperylene, and belongs to the field of piperylene refining. BACKGROUND

[0002] With the continuous expansion of the ethylene production scale in China, the yield of cracking C5 fraction is increasingly rich. The C5 fraction is rich in diene hydrocarbons such as piperylene, isoprene and cyclopentadiene. These diene hydrocarbons are important resources for chemical utilization due to their active chemical properties.

[0003] Due to the small boiling point difference and the existence of azeotropy, the piperylene obtained from the C5 separation process is crude piperylene, and the main components are piperylene, cyclopentene and cyclopentane, wherein the content of piperylene is 65-75%, the content of cyclopentene and cyclopentane is 18-25%, and the content of cyclopentadiene and alkyne (1-pentyne, 2-pentyne, 1-pentene-3-alkyne and 3-pentene-1-alkyne) is 0.5-2%. The existence of impurities such as cyclopentadiene and hydrocarbon alkyne has a toxic effect on the polymerization catalyst of piperylene. When the purity of piperylene is not high, it can only be used to prepare C5 petroleum resin and curing agent, and the comprehensive utilization value is single. If the crude piperylene is refined to make the content of cyclopentadiene less than 5 ppm and the content of alkyne less than 20 ppm, it can be used to synthesize thermoplastic elastomers, and the value is greatly improved.

[0004] Due to the extremely similar boiling points of various components in the crude piperylene raw material, the ordinary rectification method cannot remove cyclopentadiene and alkyne. At present, the removal of cyclopentadiene and alkyne adopts methods such as extractive rectification, selective hydrogenation, dimerization reaction rectification, adsorption, super rectification and chemical removal.

[0005] CN107840777 discloses a method for chemically removing trace cyclopentadiene from piperylene, in which potassium hydroxide is dissolved in n-butanol, then piperylene and cyclohexanone are added, and the mixture is reacted at room temperature for 3-4 days, and then piperylene is obtained by rectification. However, the treated piperylene still contains about 10 ppm of cyclopentadiene and about 150 ppm of alkyne, which still has a great influence on the polymerization catalyst.

[0006] CN105481631 discloses a method for refining piperylene, in which cyclopentadiene is removed by thermal dimerization, then cyclopentene and cyclopentane are removed by extractive rectification, and finally 99.1% piperylene is obtained by desorption. The dimerization reaction can remove most of the cyclopentadiene, but a very long dimerization reaction time is required to completely remove the cyclopentadiene, and there are many side reactions.

[0007] CN105585412 discloses a method for preparing polymerization grade piperylene, 99.2% piperylene is obtained by first extractive rectification-stripping, dimerization, heavy removal, second extractive rectification-stripping. In extractive rectification, due to the fact that cyclopentadiene and alkyne are more soluble in the solvent than piperylene, the method of extractive rectification can remove components such as isopentene and isopentane with relatively high relative volatility, but cyclopentadiene and alkyne cannot be completely removed from piperylene, and 150 ppm of cyclopentadiene and 200 ppm of alkyne are still contained in piperylene.

[0008] CN109721456 discloses a method for preparing polymerization grade piperylene, more than 99% piperylene is obtained by selective hydrogenation, extractive rectification-stripping and other steps. In the selective hydrogenation of piperylene to remove cyclopentadiene and alkyne, due to the fact that the hydrogenation of cycloalkene is more difficult than that of alkene, a large amount of piperylene is lost in the process of hydrogenation removal of cyclopentadiene.

[0009] Therefore, it is of great significance to develop a refining method for polymerization grade piperylene with high removal degree of cyclopentadiene and alkyne, low cost and green environmental protection. SUMMARY

[0010] In view of the deficiencies of the prior art, the purpose of the present application is to provide a refining method for polymerization grade piperylene. The method has high removal degree of cyclopentadiene and alkyne, high product purity, and the chemical treatment agent can be recycled, has low cost and is green and environmentally friendly.

[0011] In order to achieve the above technical purpose, the present application provides a refining method for polymerization grade piperylene, which comprises the following steps: removing alkyne by selective hydrogenation reaction of crude piperylene material to obtain piperylene intermediate after alkyne removal; removing cyclopentadiene by reaction rectification of the piperylene intermediate after alkyne removal mixed with cyclic ketone, alcohol and organic base to obtain piperylene after ring removal; and purifying the piperylene after ring removal by water washing and extractive rectification.

[0012] In the process of reaction rectification, the organic base and the cyclic ketone compound are converted into an intermediate onium salt, and then the intermediate onium salt reacts with a small amount of cyclopentadiene under the action of alcohol to generate a high-boiling-point fulvene, so that the cyclopentadiene is removed by reaction rectification, and the purity of the piperylene product is effectively improved.

[0013] As a preferred scheme, the selective hydrogenation reaction is carried out in a bubble reactor.

[0014] As a preferred scheme, in the process of the selective hydrogenation reaction, the molar ratio of alkyne in the crude piperylene material to hydrogen is 1:2-5.

[0015] As a preferred scheme, the selective hydrogenation reaction condition is that the catalyst is a lead-modified supported palladium catalyst, the temperature is 30-40℃, the pressure is 0.1-0.3 MPa, the liquid volume space velocity is 10-20 h -1 The present application can improve the removal rate of alkynes and ensure the yield of piperylene by controlling suitable selective hydrogenation reaction conditions. If the hydrogenation temperature and pressure are too low and the space velocity is too high, or the hydrogen-alkyne ratio is too small, the removal rate of alkynes is reduced. If the hydrogenation temperature and pressure are too high, the space velocity is too low, or the hydrogen-alkyne ratio is too large, the removal rate of alkynes is high, but the loss rate of piperylene during hydrogenation is increased.

[0016] As a preferred scheme, in the lead-modified supported palladium catalyst, the content of palladium is 0.20-0.30 wt%, the content of lead is 0.10-0.15 wt%, and the carrier is active alumina.

[0017] The present application uses a lead-modified palladium hydrogenation catalyst, reduces the number of active sites of the catalyst, and reduces the activity of the catalyst. In combination with specific hydrogenation process conditions, the hydrogenation of piperylene can be effectively inhibited without affecting the hydrogenation of alkynes. The relative adsorption rate of unsaturated hydrocarbons on the active sites of the metal catalyst is: alkyne > diene > olefin. The concentration of alkyne on the surface of the catalyst is much higher than that of piperylene, so that the hydrogenation reaction is mainly alkyne, and the purpose of removing alkyne by selective hydrogenation is achieved.

[0018] As a preferred scheme, the addition amount of the cyclic ketone is 15-20 wt% of the piperylene intermediate.

[0019] As a preferred scheme, the molar ratio of the cyclic ketone, the alcohol, and the organic base is 1:0.5-2:0.04-0.2. Controlling the amount of the cyclic ketone, the alcohol, and the organic base in a suitable range is beneficial to improve the refining efficiency. If the amount of the cyclic ketone, the alcohol, and the organic base is too small, the reaction rate is low, the reaction time is long, and the removal rate of cyclopentadiene is low. If the amount of the cyclic ketone, the alcohol, and the organic base is too large, the refining cost of piperylene is increased.

[0020] As a preferred scheme, the cyclic ketone includes cyclopentanone and / or cyclohexanone. The cyclic ketone compound is easy to form an intermediate onium salt with the organic base. If a short-chain carbon ketone such as acetone is used, the difficulty of subsequent rectification separation is increased due to its low boiling point. If a long-chain carbon ketone is used, there are problems such as large steric hindrance, slow reaction rate, and low removal rate.

[0021] As a preferred scheme, the alcohol includes at least one of methanol, ethanol, and isopropyl alcohol. The alcohol used in the present application has a good promoting effect on the reaction.

[0022] As a preferred solution, the organic base comprises tetrahydro-pyrrole and / or hexahydro-pyridine. The organic bases used in the present application are all heterocyclic compounds containing nitrogen atoms, and their nitrogen atoms can provide lone electron pairs, thus showing high basicity. The structures of the two compounds are relatively stable, and they are not prone to decomposition during the reaction, thus favoring the removal of trace cyclopentadiene.

[0023] As a preferred solution, the reaction rectification is carried out in a reaction rectification column, the pressure of the reaction rectification column is normal pressure, the top temperature is 36-41℃, the bottom temperature is 70-80℃, and the reflux ratio is 2-5. The de-alkyne intermediate product is introduced from the lower part of the reaction rectification column, and the cyclic ketone, alcohol and organic base are introduced from the upper part of the reaction rectification column.

[0024] As a preferred solution, part of the bottom discharge of the reaction rectification column is directly returned to the upper part of the reaction rectification column for recycling, and part of the bottom discharge of the reaction rectification column is subjected to vacuum rectification to remove heavy components generated by the reaction of cyclopentadiene and cyclic ketone, and then returned to the upper part of the reaction rectification column for recycling.

[0025] As a preferred solution, the process of removing heavy components generated by the reaction of cyclopentadiene and cyclic ketone by vacuum rectification is carried out in a heavy component removal column, the operating pressure is 10-20kPa, the top temperature is 30-50℃, the bottom temperature is 120-140℃, and the reflux ratio is 1-2.

[0026] As a preferred solution, the water washing is carried out by continuous water washing in a water washing column. The water washing column is a packed column, and the water and the de-cycloalkene intermediate product are countercurrently contacted, and a small amount of alcohol and organic base in the cycloalkene intermediate product are washed into the water phase and discharged from the bottom of the water washing column.

[0027] As a preferred solution, the water phase discharged from the bottom of the water washing column is subjected to water phase rectification to recover the alcohol and organic base therein, and then returned to the reaction rectification column for recycling.

[0028] As a preferred solution, the water phase rectification is carried out in an alcohol recovery column, the operating pressure is normal pressure, the top temperature is 64-65℃, the bottom temperature is 100-105℃, and the reflux ratio is 0.5-1.

[0029] As a preferred solution, the extractive rectification is carried out in an extractive rectification column, and the extractive rectification column is a partitioned extractive rectification column. The use of a partitioned extractive rectification column can reduce equipment investment, effectively avoid back mixing between components, improve thermodynamic efficiency, and reduce energy consumption of the device.

[0030] As a preferred solution, the partitioned extractive rectification column is divided into a left upper extractive rectification side, a right upper desorption side, and a lower common stripping section.

[0031] As a preferred scheme, N,N-dimethylformamide (DMF) is used as the extractant in the extractive rectification process.

[0032] As a preferred scheme, the mass ratio of N,N-dimethylformamide to de-cyclopentadiene is 8-15:1. Too low solvent ratio will affect the purity of piperylene, and too high solvent ratio will result in large amount of extractant recovery and increase the refining cost of piperylene.

[0033] As a preferred scheme, in the extractive rectification process, the feed temperature of the water-washed de-cyclopentadiene is 30-40℃, the overhead temperature of the extractive rectification side is 44-46℃, the overhead temperature of the desorption side is 42-43℃, and the column bottom temperature of the extractive rectification column is 140-160℃.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] (1) The cyclopentadiene content in the piperylene product obtained by the present application is less than 1.0 ppm, the acetylene content is less than 20 ppm, and the loss rate of piperylene during refining is low;

[0036] (2) In the present application, the organic base and the cyclic ketone compound are converted into an intermediate onium salt in the reaction rectification process, and then the intermediate onium salt reacts with a small amount of cyclopentadiene in the presence of alcohol to generate high-boiling fulvene and piperylene, which are separated, thereby achieving effective removal of cyclopentadiene and improving the purity of piperylene product;

[0037] (3) The whole process flow of the present application is simple, all raw materials used are liquid, the reaction time is short, the cycle is short, all treatment agents in the refining process can be recycled, internal circulation is achieved, and the production cost is significantly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0039] Figure 1 The process flow chart of the refining method of polymer-grade piperylene of the present application, wherein R1 is a hydrogenation reactor; R2 is a reaction rectification column; C1 is a water washing column; C2 is an extractive rectification column with a partition; C3 is an alcohol recovery column; and C4 is a heavy component removal column. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be clearly and completely described below with reference to the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0041] The present application uses crude piperylene by-produced in the cracking of naphtha to produce ethylene as raw material, and the main components are shown in Table 1.

[0042] Table 1 Composition of crude piperylene

[0043]

[0044]

[0045] The crude piperylene raw material and H2 enter the hydrogenation reactor R1 to perform selective hydrogenation reaction, and the material after removal of acetylenic hydrocarbons enters the lower part of the reaction rectification column R2, while the cyclic ketone, alcohol and organic base are added from the upper part of the reaction rectification column R2 to perform reaction rectification. The cyclopentadiene in the reaction rectification column reacts with the cyclic ketone to generate heavy components, which are taken out from the column bottom together with the cyclic ketone, alcohol and organic base. Part of the heavy components is directly recycled back to the upper part of the R2, and the other part enters the heavy component removal column C4 for rectification. The heavy components are discharged from the C4 column bottom, and the cyclic ketone, alcohol and organic base are distilled from the C4 column top and returned to the upper part of the reaction rectification column. The piperylene component from which the cyclopentadiene is removed is distilled from the top of the reaction rectification column R2, enters the lower part of the water washing column C1, and is countercurrently extracted with water introduced from the upper part of the water washing column. A small amount of alcohol and organic base in the piperylene component is dissolved in the water phase, which is discharged from the bottom of the water washing column C1 to the recovery column C3 for rectification. Waste water is discharged from the C3 column bottom, and the alcohol and organic base distilled from the C3 column top are returned to the upper part of the reaction rectification column R2. The piperylene component after water washing enters the extraction rectification column C2 with a partition for extraction rectification. Carbon five enters the lower part of the extraction rectification side, and the extractant enters the upper part of the extraction rectification side. Components such as cyclopentane and cyclopentene are distilled from the top of the extraction rectification side, and the extractant and piperylene enter the common stripping section of C2. The extractant is discharged from the column bottom and recycled to the upper part of the extraction rectification side, and the piperylene is distilled from the top of the stripping side of C2.

[0046] The composition of the piperylene is analyzed by gas chromatography according to the standard SH / T 1790-2015.

[0047] Example 1

[0048] A Φ25mm x 1200mm fixed bed hydrogenation reactor R1 was charged with 100ml of selective hydrogenation catalyst QSH-06 (Shandong Qilu Kelai Chemical Research Institute Co., Ltd.), the crude metapenta-diene was introduced into the hydrogenation reactor R1 together with H2 for selective hydrogenation reaction, the hydrogenation reaction conditions were temperature 30℃, pressure 0.3MPa, liquid volume space velocity 10h -1 , the molar ratio of acetylene in the crude metapenta-diene to hydrogen was 1:3, and the crude metapenta-diene after selective hydrogenation was introduced into a reaction rectification column R2 after the hydrogen was separated out by gas-liquid separation.

[0049] R2 was a plate-type rectification column with 80 plates, the crude metapenta-diene was introduced from the 72nd plate at a feed rate of 680g / h, and the reaction liquid was introduced from the 10th plate at a feed rate of 251g / h, the molar ratio of cyclopentanone to methanol to tetrahydro-pyrrole in the reaction liquid was 1:2:0.1, and the amount of cyclopentanone was 20wt% of the crude metapenta-diene, the cyclopentadiene in the crude metapenta-diene reacted with the ketone to form heavy components, and the other carbon five components were distilled out from the top of the column, the top pressure of the column was normal pressure, the top temperature was 37℃, the bottom temperature was 80℃, and the reflux ratio was 3, most of the bottom liquid was directly recycled to the upper part of the R2, and the other part was introduced into a heavy component removal column C4 for rectification, the operation pressure of the heavy component removal column was 10kPa, the top temperature was 43℃, the bottom temperature was 127℃, the reflux ratio was 1, the heavy components were discharged from the bottom of the column, and the top fraction was returned to the reaction rectification column for repeated use.

[0050] The metapenta-diene component from which the cyclopentadiene was removed was distilled out from the top of the reaction rectification column R2 at a rate of 697g / h, was introduced into the lower part of a water washing column C1, and was countercurrently contacted with water at a flow rate of 60g / h in the column, the methanol and tetrahydro-pyrrole in the column were dissolved in the water, were discharged from the bottom of the column, and were introduced into a recovery column C3 at a flow rate of 85g / h, the operation pressure of the recovery column C3 was normal pressure, the top temperature was 64.5℃, the bottom temperature was 103℃, and the reflux ratio was 0.8.

[0051] The metapenta-diene component flowing out from the top of the water washing column C1 was introduced into the extractive rectification side of an extractive rectification column at a rate of 672g / h, the extractant DMF was adjusted to 45℃, and was then introduced into the upper part of the extractive rectification side, the molar ratio of metapenta-diene to DMF was 1:10 (wt%), the cyclopentane and cyclopentene were distilled out from the top of the extractive rectification side, the top temperature was 45℃, and the reflux ratio was 5, the DMF and the metapenta-diene were separated in the common rectification section of the extractive rectification column, the DMF was discharged from the bottom of the column and was returned to the upper part of the extractive rectification side, and the bottom temperature was 148℃, the metapenta-diene was distilled out from the top of the desorption side of the extractive rectification column, the top temperature was 42.1℃, and the reflux ratio was 8, the composition of the polymerization grade metapenta-diene was shown in Table 2, and the metapenta-diene yield was 96.8%.

[0052] Table 2 Composition of polymerization grade metapenta-diene

[0053] Component Content / wt% Component Content / wt% n-Pentane 0 Cyclopentadiene 0 Isoprene 0 Cis-piperylene 40.5271 1-Pentyne 0.0004 3-Penten-1-yne 0 2-Pentene 0.0110 2-Pentyne 0.0008 2-Methyl-2-butene 0 Cyclopentene 0.3235 Trans-piperylene 58.9221 Cyclopentane 0.1572 1-Penten-3-yne 0.0005 Others 0.0553 3-Methyl-1,2-butadiene 0.0021

[0054] Example 2

[0055] The Φ25mm x 1200mm fixed bed hydrogenation reactor R1 was packed with 100ml of selective hydrogenation catalyst QSH-06 (Shandong Qilu Kelun Chemical Research Institute Co., Ltd.), and the crude metapenta-diene was introduced into the hydrogenation reactor R1 together with H2 for selective hydrogenation reaction. The hydrogenation reaction conditions were temperature 35℃, pressure 0.2MPa, liquid volume space velocity 15h -1 The molar ratio of alkynes in the crude metapenta-diene to hydrogen was 1:4. After the selective hydrogenation of the crude metapenta-diene, the hydrogen was separated from the liquid by gas-liquid separation, and the crude metapenta-diene was introduced into the reaction rectification column R2.

[0056] The R2 was a plate rectification column with 80 plates. The crude metapenta-diene was introduced from the 72nd plate at a speed of 1020g / h, and the reaction liquid was introduced from the 10th plate at a speed of 250g / h. The reaction liquid contained cyclohexanone, methanol and tetrahydro-pyrrole at a molar ratio of 1:1.5:0.2, and the amount of cyclohexanone was 15wt% of the crude metapenta-diene. The cyclopentadiene in the crude metapenta-diene reacted with the ketone to form heavy components, and the other carbon five components were distilled from the top of the column. The pressure at the top of the column was atmospheric pressure, the temperature at the top of the column was 37.5℃, the temperature at the bottom of the column was 80℃, and the reflux ratio was 5. Most of the liquid at the bottom of the column was directly recycled to the upper part of the R2, and a part of it was introduced into the heavy component removal column C4 for rectification. The operation pressure of the heavy component removal column was 10kPa, the top temperature was 48℃, the bottom temperature was 140℃, and the reflux ratio was 2. The heavy components were discharged from the bottom of the column, and the top fraction was returned to the reaction rectification column for repeated use.

[0057] The metapenta-diene component 1043g / h, from which the cyclopentadiene was removed, was distilled from the top of the reaction rectification column R2, and was introduced into the lower part of the water washing column C1 for countercurrent contact with water at a flow rate of 104g / h. The methanol and tetrahydro-pyrrole in the metapenta-diene were dissolved in the water, and were discharged from the bottom of the column into the recovery column C3 at a flow rate of 118g / h. The operation pressure of the recovery column C3 was atmospheric pressure, the top temperature was 64.6℃, the bottom temperature was 105℃, and the reflux ratio was 1.

[0058] The metapenta-diene component flowing out from the top of the water washing column C1 was introduced into the extractive rectification side of the extractive rectification column at a speed of 1005g / h, and the extractant DMF was introduced into the upper part of the extractive rectification side after being adjusted to 50℃. The ratio of metapenta-diene to DMF was 1:15 (wt%). The cyclopentane and cyclopentene were distilled from the top of the extractive rectification side at a temperature of 45.5℃, and the reflux ratio was 4. The DMF and metapenta-diene were separated in the common rectification section of the extractive rectification column. The DMF was discharged from the bottom of the column and returned to the upper part of the extractive rectification side, and the bottom temperature was 146℃. The metapenta-diene was distilled from the top of the desorption side of the extractive rectification column at a temperature of 42.2℃, and the reflux ratio was 6. The composition of the polymerization grade metapenta-diene is shown in Table 3, and the yield of metapenta-diene was 96.3%.

[0059] Table 3 Composition of polymerization grade metapenta-diene

[0060]

[0061]

[0062] Example 3

[0063] In a Φ25mmx1200mm fixed bed hydrogenation reactor R1, 50ml of selective hydrogenation catalyst QSH-06 (Shandong Qilu Keli Chemical Research Institute Co., Ltd.) was loaded, and the crude metapenta-diene was introduced into the hydrogenation reactor R1 together with H2 for selective hydrogenation reaction. The hydrogenation reaction conditions were temperature 40℃, pressure 0.1MPa, liquid volume space velocity 20h-1, molar ratio of alkyne to hydrogen in the crude metapenta-diene 1:5, and the crude metapenta-diene after selective hydrogenation was introduced into the reaction rectification column R2 after the hydrogen was separated out by gas-liquid separation. -1

[0064] R2 was a plate-type rectification column with 80 plates, and the crude metapenta-diene was introduced from the 72nd plate at a speed of 680g / h, and the reaction liquid was introduced from the 10th plate at a speed of 223g / h, wherein the molar ratio of cyclopentanone:ethanol: tetrahydropyrrole in the reaction liquid was 1:1:0.1, and the amount of cyclopentanone was 20wt% of the crude metapenta-diene. The cyclopentadiene in the crude metapenta-diene reacted with the ketone to form heavy components, and other carbon five components were distilled out from the top of the column. The pressure at the top of the column was normal pressure, the temperature at the top of the column was 39℃, the temperature at the bottom of the column was 70℃, the reflux ratio was 5, and most of the liquid at the bottom of the column was directly recycled to the upper part of R2, and the other part was introduced into the heavy component removal column C4 for rectification. The operating pressure of the heavy component removal column was 20kPa, the top temperature was 49℃, the bottom temperature was 125℃, the reflux ratio was 2, the heavy components were discharged from the bottom of the column, and the top fraction was returned to the reaction rectification column for repeated use.

[0065] The metapenta-diene component from which the cyclopentadiene was removed was distilled out from the top of the reaction rectification column R2 at a speed of 696g / h, introduced into the lower part of the water washing column C1, and countercurrently contacted with water at a speed of 60g / h in the column, wherein the ethanol and tetrahydropyrrole were dissolved in water, discharged from the bottom of the column, and introduced into the recovery column C3 at a speed of 85g / h. The operating pressure of the recovery column C3 was normal pressure, the top temperature was 78.1℃, the bottom temperature was 105℃, and the reflux ratio was 1.0.

[0066] ​The piperylene component from the top of the water scrubber C1 entered the extractive distillation side of the extractive distillation column at a rate of 672 g / h, the extractant DMF was adjusted to 40°C and entered the extractive distillation side from the top of the extractive distillation side, piperylene:DMF = 1:12 (wt%), cyclopentane and cyclopentene were distilled from the top of the extractive distillation side, the column top temperature was 45.2°C, and the reflux ratio was 5. DMF and piperylene entered the common stripping section of the extractive distillation column and were separated, DMF was discharged from the column bottom and returned to the top of the extractive distillation side, the column bottom temperature was 150°C. Piperylene was distilled from the top of the desorption side of the extractive distillation column, the column top temperature was 42.2°C, the reflux ratio was 6, the polymerization grade piperylene composition is shown in Table 4, and the piperylene yield was 96.3%.

[0067] Table 4 Polymerization grade piperylene composition

[0068]

[0069]

[0070] Example 4

[0071] A Φ25mm x 1200mm fixed bed hydrogenation reactor R1 was filled with 100ml of a selective hydrogenation catalyst QSH-06 (Shandong Qilu Kelu Chemical Research Institute Co., Ltd.), crude piperylene and H2 entered the hydrogenation reactor R1 for selective hydrogenation, the hydrogenation reaction conditions were a temperature of 30°C, a pressure of 0.2MPa, a liquid volume space velocity of 10h -1 , the molar ratio of acetylene to hydrogen in the crude piperylene was 1:2, and the crude piperylene after selective hydrogenation entered the reaction distillation column R2 after gas-liquid separation of hydrogen.

[0072] R2 was a plate distillation column with 80 plates, crude piperylene was fed from the 72nd plate at a rate of 680g / h, and reaction liquid was fed from the 10th plate at a rate of 191g / h, the reaction liquid contained cyclopentanone:isopropyl alcohol:hexahydropyridine = 1:0.5:0.04 (molar ratio), and the amount of cyclopentanone was 20wt% of the crude piperylene, cyclopentadiene in the crude piperylene reacted with the ketone to form heavy components, and other carbon five components were distilled from the top of the column. The column top pressure was atmospheric pressure, the column top temperature was 40°C, the column bottom temperature was 79°C, the reflux ratio was 2, most of the column bottom liquid was directly recycled to the upper part of R2, and the other part entered the heavy component removal column C4 for distillation, the heavy component removal column operated at a pressure of 10kPa, the top temperature was 43.3°C, the column bottom temperature was 132°C, the reflux ratio was 1, the heavy components were discharged from the column bottom, and the column top fraction was returned to the reaction distillation column for repeated use.

[0073] The cyclopentadiene-removed piperylene component 695 g / h distilled from the top of the reactive rectification column R2 was introduced into the lower part of the water washing column C1 and contacted countercurrently with water at a flow rate of 60 g / h. The isopropyl alcohol and tetrahydro-pyrrole in the water were removed from the column bottom and introduced into the recovery column C3 at a flow rate of 87 g / h. The recovery column C3 was operated at atmospheric pressure, the top temperature was 80.2°C, the bottom temperature was 103°C, and the reflux ratio was 1.0.

[0074] The piperylene component flowed out from the top of the water washing column C1 was introduced into the extractive rectification side of the extractive rectification column at a flow rate of 672 g / h. The extractant DMF was adjusted to 40°C and introduced into the upper part of the extractive rectification side. The piperylene:DMF ratio was 1:12 (wt%). The cyclopentane and cyclopentene were distilled from the top of the extractive rectification side. The top temperature was 45.5°C and the reflux ratio was 6. The DMF and piperylene were separated in the common stripping section of the extractive rectification column. The DMF was removed from the column bottom and returned to the upper part of the extractive rectification side. The bottom temperature was 148°C. The piperylene was distilled from the top of the desorption side of the extractive rectification column. The top temperature was 42.2°C and the reflux ratio was 6. The polymerization grade piperylene composition is shown in Table 5. The piperylene yield was 96.5%.

[0075] Table 5 Polymerization grade piperylene composition

[0076] Component Content / wt% Component Content / wt% n-Pentane 0 Cyclopentadiene 0.0001 Isoprene 0 Cis-piperylene 40.5227 1-Pentyne 0.0004 3-Penten-1-yne 0.0003 2-Pentene 0.0133 2-Pentyne 0.0005 2-Methyl-2-butene 0 Cyclopentene 0.3243 Trans-piperylene 58.9237 Cyclopentane 0.1431 1-Penten-3-yne 0.0006 Others 0.0657 3-Methyl-1,2-butadiene 0.0026

[0077] Comparative Example 1

[0078] The purification method of Example 1 was used, except that the selective hydro-de-alkyne step was omitted.

[0079] The crude piperylene (main components shown in Table 1) was directly introduced into the reactive rectification column R2.

[0080] The R2 was a plate rectification column with 80 plates. The crude piperylene was introduced into the 72nd plate at a flow rate of 680 g / h. The reaction liquid was introduced into the 10th plate at a flow rate of 251 g / h. The reaction liquid contained cyclopentanone:methanol: tetrahydro-pyrrole = 1:2:0.1 (mole ratio). The cyclopentadiene in the crude piperylene reacted with the ketone to form heavy components, and the other carbon five components were distilled from the top of the column. The top pressure was atmospheric pressure, the top temperature was 37.1°C, the bottom temperature was 80°C, and the reflux ratio was 3. Most of the column bottom liquid was directly recycled to the upper part of the R2. A part of the column bottom liquid was introduced into the heavy component removal column C4 for rectification. The heavy component removal column was operated at a pressure of 10 kPa, the top temperature was 43°C, the bottom temperature was 127°C, and the reflux ratio was 1. The heavy components were removed from the column bottom, and the top fraction was returned to the reactive rectification column for reuse.

[0081] The cyclopentadiene-removed piperylene component 697 g / h distilled from the top of the reactive rectification column R2 was introduced into the lower part of the water washing column C1 and contacted countercurrently with water at a flow rate of 60 g / h, in which the methanol and tetrahydropyrrole were dissolved in water and discharged from the column bottom into the recovery column C3 at a flow rate of 85 g / h. The recovery column C3 was operated at normal pressure, with a top temperature of 64.5°C, a bottom temperature of 103°C and a reflux ratio of 0.8.

[0082] The piperylene component flowed out from the top of the water washing column C1 was introduced into the extractive rectification side of the extractive rectification column at a rate of 672 g / h, and the extractant DMF was introduced into the upper part of the extractive rectification side after being adjusted to a temperature of 45°C. The piperylene:DMF ratio was 1:10 (wt%) and cyclopentane and cyclopentene were distilled from the top of the extractive rectification side at a temperature of 45°C and a reflux ratio of 5. DMF and piperylene were separated in the common stripping section of the extractive rectification column, DMF was discharged from the column bottom and returned to the upper part of the extractive rectification side at a temperature of 148°C. Piperylene was distilled from the top of the desorption side of the extractive rectification column at a temperature of 42.2°C and a reflux ratio of 8. The purified piperylene composition is shown in Table 6, and the piperylene yield was 98.0%.

[0083] Table 6 Purified piperylene composition

[0084] Component Content / wt% Component Content / wt% n-Pentane 0 Cyclopentadiene 0 Isoprene 0 Cis-piperylene 40.2527 1-Pentyne 0.0792 3-Penten-1-yne 0.0961 2-Pentene 0.0142 2-Pentyne 0.1034 2-Methyl-2-butene 0 Cyclopentene 0.4235 Trans-piperylene 58.7235 Cyclopentane 0.1236 1-Penten-3-yne 0.0926 Others 0.0886 3-Methyl-1,2-butadiene 0.0026

[0085] Comparative Example 2

[0086] The purification method of Example 1 was used, except that the step of removing cyclopentadiene by reactive rectification was omitted.

[0087] A Φ25 mm x 1200 mm fixed-bed hydrogenation reactor R1 was packed with 100 ml of a selective hydrogenation catalyst QSH-06 (Shandong Qilu Kelu Chemical Industry Research Institute Co., Ltd.), and the crude piperylene (main composition shown in Table 1) was introduced into the hydrogenation reactor R1 together with H2 for selective hydrogenation reaction. The hydrogenation reaction conditions were a temperature of 30°C, a pressure of 0.3 MPa, a liquid volume space velocity of 10 h -1 The molar ratio of the alkyne in the crude piperylene to hydrogen was 1:3, and the crude piperylene after selective hydrogenation was introduced into the extractive rectification column C2 after gas-liquid separation of hydrogen.

[0088] The piperylene component from the selective hydrogenation reactor was fed into the extractive rectification side of the extractive rectification column at a rate of 680 g / h. The extractant DMF was adjusted to 45°C and fed into the upper part of the extractive rectification side. The ratio of piperylene to DMF was 1:10 (wt%). Cyclopentane and cyclopentene were distilled from the top of the extractive rectification side at a column top temperature of 45°C and a reflux ratio of 5. DMF and piperylene were separated in the common stripping section of the extractive rectification column. DMF was removed from the bottom of the column and returned to the upper part of the extractive rectification side. The column bottom temperature was 148°C. Piperylene was removed from the top of the stripping side of the extractive rectification column at a column top temperature of 42.2°C and a reflux ratio of 8. The purified piperylene composition is shown in Table 7. The piperylene yield was 96.5%.

[0089] Table 7 Purified piperylene composition

[0090] Component Content / wt% Component Content / wt% n-Pentane 0 Cyclopentadiene 0.0395 Isoprene 0 Cis-piperylene 40.3567 1-Pentyne 0.0004 3-Penten-1-yne 0.0005 2-Pentene 0.0142 2-Pentyne 0.0005 2-Methyl-2-butene 0 Cyclopentene 0.4238 Trans-piperylene 58.9537 Cyclopentane 0.1246 1-Penten-3-yne 0.0006 Others 0.0828 3-Methyl-1,2-butadiene 0.0027

[0091] Comparative Example 3

[0092] The purification method of Example 1 was used, except that the amount of cyclopentanone added in the reaction rectification was 10 wt% of the crude piperylene. The feed rate of the reaction liquid was 125.5 g / h. The purified piperylene composition is shown in Table 8. The piperylene yield was 96.6%.

[0093] Table 8 Purified piperylene composition

[0094] Component Content / wt% Component Content / wt% n-Pentane 0 Cyclopentadiene 0.0028 Isoprene 0 Cis-piperylene 40.5225 1-Pentyne 0.0004 3-Penten-1-yne 0 2-Pentene 0.0112 2-Pentyne 0.0008 2-Methyl-2-butene 0 Cyclopentene 0.3237 Trans-piperylene 58.9228 Cyclopentane 0.1575 1-Penten-3-yne 0.0005 Others 0.0552 3-Methyl-1,2-butadiene 0.0026

[0095] Comparative Example 4

[0096] The purification method of Example 1 was used, except that the ratio of cyclopentanone to methanol to tetrahydropyrrole in the reaction liquid was 1:0.3:0.1 (molar ratio). The feed rate was 163 g / h. The purified piperylene composition is shown in Table 9. The piperylene yield was 96.3%.

[0097] Table 9 Purified piperylene composition

[0098] Component Content / wt% Component Content / wt% n-Pentane 0 Cyclopentadiene 0.0053 Isoprene 0 Cis-piperylene 40.5231 1-Pentyne 0.0005 3-Penten-1-yne 0 2-Pentene 0.0112 2-Pentyne 0.0008 2-Methyl-2-butene 0 Cyclopentene 0.3235 Trans-piperylene 58.9232 Cyclopentane 0.1578 1-Penten-3-yne 0.0005 Others 0.0514 3-Methyl-1,2-butadiene Component Content / wt% Component Content / wt% n-Pentane Cyclopentadiene Isoprene Cis-piperylene 1-Pentyne 3-Penten-1-yne 2-Pentene 2-Pentyne 2-Methyl-2-butene Cyclopentene Trans-piperylene Cyclopentane 1-Penten-3-yne Others 3-Methyl-1,2-butadiene 0.0027

[0099] Comparative Example 5

[0100] The purification method of Example 1 was used, except that the ratio of cyclopentanone to methanol to tetrahydropyrrole in the reaction liquid was 1:2:0.03 (molar ratio). The feed rate was 243 g / h. The purified piperylene composition is shown in Table 10. The piperylene yield was 96.5%.

[0101] Table 10 Purified piperylene composition

[0102]

[0103]

[0104] In Examples 1-4, the content of piperylene in the polymerization grade piperylene product is greater than 99%, the content of cyclopentadiene is less than 1 ppm, and the content of acetylene is less than 20 ppm. In Comparative Example 1, the piperylene product is purified by combining reactive distillation and extractive distillation, and the content of acetylene in the product is greater than 0.3%; in Comparative Example 2, the piperylene product is purified by combining selective hydrogenation and extractive distillation, and the content of cyclopentadiene in the product is greater than 0.03%; and the experimental results of Comparative Examples 3-5 show that, by reducing the amount of cyclic ketone, alcohol, and organic base used in the reactive distillation process, the content of cyclopentadiene in the refined piperylene product is greater than 18 ppm, but is still better than that of Comparative Example 2.

[0105] Many modifications to these examples will be readily apparent to those of ordinary skill in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Accordingly, the present application is not to be limited to these examples as illustrated, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for purifying polymer-grade isoprene, characterized in that: Crude isoprene is selectively hydrogenated to remove alkynes, yielding de-alkyne isoprene intermediate. The de-alkyne isoprene intermediate is then mixed with cyclic ketones, alcohols, and organic bases for reactive distillation to remove cyclopentadiene, yielding decyclic isoprene. The decyclic isoprene is then purified by water washing and extractive distillation to obtain the final product.

2. The method for purifying polymer-grade isoprene according to claim 1, characterized in that: During the selective hydrogenation reaction, the molar ratio of alkyne to hydrogen in the crude isoprene material is 1:2 to 5.

3. A method for purifying polymer-grade isoprene according to claim 1 or 2, characterized in that: The conditions for the selective hydrogenation reaction are as follows: the catalyst is a lead-modified supported palladium catalyst, the temperature is 30–40 °C, the pressure is 0.1–0.3 MPa, and the liquid hourly space velocity is 10–20 h⁻¹. -1 .

4. The method for purifying polymer-grade isoprene according to claim 3, characterized in that: The lead-modified supported palladium catalyst contains 0.20–0.30 wt% palladium and 0.10–0.15 wt% lead, and the support is activated alumina.

5. The method for purifying polymer-grade isoprene according to claim 1, characterized in that: The amount of the cyclic ketone added is 15-20 wt% of the isoprene intermediate.

6. A method for purifying polymer-grade isoprene according to claim 1 or 5, characterized in that: The molar ratio of the cyclic ketone, alcohol, and organic base is 1:0.5-2:0.04-0.

2.

7. The method for purifying polymer-grade isoprene according to claim 1, characterized in that: The cyclic ketones include cyclopentanone and / or cyclohexanone; The alcohol includes at least one of methanol, ethanol, and isopropanol; The organic base includes tetrahydropyrrole and / or hexahydropyridine.

8. A method for purifying polymer-grade isoprene according to claim 1, 5, or 7, characterized in that: The reactive distillation is carried out in a reactive distillation column at atmospheric pressure, with a top temperature of 36–41°C, a bottom temperature of 70–80°C, and a reflux ratio of 2–5.

9. The method for purifying polymer-grade isoprene according to claim 8, characterized in that: The liquid discharged from the bottom of the reactive distillation column is partly returned directly to the top of the column for recycling, and partly returned to the top of the column for recycling after being subjected to vacuum distillation to remove the heavy components generated by the reaction of cyclopentadiene and cycloketone.

10. The method for purifying polymer-grade isoprene according to claim 1, characterized in that: The extractive distillation is carried out in an extractive distillation column, which is an extractive distillation column with baffles.

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