CN101104573A - Method for separating isoprene by combined rectification - Google Patents

Abstract

The invention relates to a combined isoprene rectification and separation method, mainly aimed at solving the problems in prior art that when to separate and crack the diolefin in c_5 fraction, the raw materials have to enter a thermal dimerization reactor first, resulting in great losses of isoprene and cyclopentadienyl, and that because the boiling points of isoprene and cyclopentadienyl are nearly the same, the cyclopentadienyl affects the purity of the product isoprene and a part of cyclopentadienyl is lost, and particularly the problem that the isoprene knockout tower has high temperature and is energy-consuming. The invention makes the c_5 materials enter the isoprene knockout tower2 from the middle; after separation, material flow I containing isoprene comes out from the top of the tower and the material flow II containing cyclopentadienyl comes out from the bottom of the tower for later processing. Then the material flow I enters the cyclopentadienyl recycling tower from the middle part, after separation the material flow III coming out from the top of the cyclopentadienyl recycling tower enters the follow-up isoprene refining process and the cyclopentadienyl material flow coming out from the bottom of the cyclopentadienyl recycling tower circulates to the middle part of the isoprene knockout tower2. With such technique proposal, the invention solves the problems, thus the invention can be applied to the industrial production of separating the diolefin in c_5 fraction.

Description

The method of separating isoprene by combined rectification

Technical field

The present invention relates to a kind of method of separating isoprene by combined rectification.

Background technology

Dienes such as isoprene, m-pentadiene and cyclopentadiene are rich in the C5 fraction of the quite a lot of quantity of by-product in the petroleum cracking process of producing ethylene in the C5 fraction.These diolefin chemical property are active, are important chemical material.Because the difference on raw material, cracking severity and the separation degree of petroleum hydrocarbon cracking, the diolefin content in the C5 fraction is different, but total amount is between 40～60%.Therefore, separate and utilize C5 fraction for the economic benefit that improves ethylene unit, the comprehensive utilization petroleum resources have profound significance.

Cracked C 5 fraction is close by more than 20 kinds of boiling points, and the component that easily forms azeotrope is to each other formed, and therefrom isolating purity, to meet the C 5 diene difficulty of application requiring higher, and technology is comparatively complicated, generally adopts extraction fractional distillation in the prior art.Selective solvent commonly used has dimethyl formamide (DMF) and acetonitrile, as disclosed processing methodes such as patent JP63101338, JP74019245, US3510405, US3535260.Wherein the DMF solvent have that selectivity to C 5 diene is good, solubleness big,, plurality of advantages such as corrodibility low and toxicity little five easily separated with carbon.

Because the isoprene market development is comparatively extensive than morning and application in isoprene, m-pentadiene and three kinds of C 5 dienes of cyclopentadiene, so C5 fraction separation process scheme early only is a separation utilization isoprene wherein.With petrochemical complex, the particularly development of fine chemistry industry, the market requirement of m-pentadiene and dicyclopentadiene increases day by day, and the method that further rectifying separation obtains m-pentadiene and dicyclopentadiene from the isolating heavy constituent of isoprene also comes into one's own day by day.

The key of C 5 diene sepn process is an isoprene and the separating of cyclopentadiene, and the boiling-point difference under both normal pressures is 7.45 ℃, and also can increase both separating difficulties with the azeotropic of other carbon five hydrocarbon.

The patent US3510405 of Nippon Zeon Co., Ltd. disclose a kind of from C5 fraction the processing method of separating high-purity isoprene, comprise the steps: the C5 fraction that will obtain by hydro carbons steam cracking or other high-temperature cracking method, through overheated dimerization reaction and therefrom isolate cyclopentadiene; With DMF is that solvent carries out the extractive distillation first time in the presence of stopper, and solvent is by the stripping tower recycling use; Material takes off heavy rectifying tower through one and carries out rectifying, therefrom separates the heavy constituent that contain cyclopentadiene and m-pentadiene; With DMF is that solvent carries out the extractive distillation second time in the presence of stopper, and solvent reclaims by stripping tower and uses; Material obtains highly purified isoprene product by the tower still after through a lightness-removing column rectifying.

Chinese patent CN1160035A discloses the method that a kind of liquid phase feeding extraction rectification method is separated five fractions of petroleum cracked carbon, and the flow process of isoprene separation and purification part is similar with US3510405, has improved wherein first, second extracting rectifying feed process; The tower still material of the dicyclopentadiene heavy constituent material of separation removal and weight-removing column behind the hot dimerization reaction removes processes such as carbon six hydrocarbon components by other carbon five hydrocarbon components of rectifying separation, rectifying, obtains highly purified m-pentadiene and dicyclopentadiene product.

Chinese patent CN1412165A discloses a kind of separation method of cracked C 5 fraction, principal character is after hot dimerization, rectifying separation dicyclopentadiene, carbon five materials remove alkynes by selective catalytic hydrogenation technology before carrying out extracting rectifying, thereby have saved second section extracting rectifying in traditional isoprene flow process.

A principal character of above-mentioned separating technology process is for earlier the hot dimerization of cyclopentadiene being converted into dicyclopentadiene, then separating in the Rich in isoprene material of heavy constituent such as dicyclopentadiene.But in the hot dimerization of cyclopentadiene, isoprene also has polymerization to a certain degree, and can and cyclopentadiene copolymerization is largely arranged.The generation of the dipolymer beyond these dicyclopentadiene has caused a large amount of losses of isoprene and cyclopentadiene, causes the yield raising of isoprene and dicyclopentadiene to be restricted.

Because the boiling point of the codimerization thing of isoprene dipolymer and isoprene and m-pentadiene is close with the boiling point of dicyclopentadiene, be difficult to separate, make the purity of dicyclopentadiene be subjected to influence, also just influenced the utility value of dicyclopentadiene.In order to improve the purity of dicyclopentadiene, just must increase the stage number or the bed stuffing height of rectifying tower or increase quantity of reflux, thereby increase facility investment or energy consumption.

In order to remedy above-mentioned technical disadvantages, Chinese patent CN1253130A disclose a kind of from C5 fraction the method for separating diolefin, reactive distillation is carried out in C5 fraction, when making cyclopentadiene generation dimerization reaction by reactive distillation, isoprene is separated by cat head, and material is through rectifying separation m-pentadiene, dicyclopentadiene.Reactive distillation cat head product obtains highly purified isoprene through operations such as first, second extractive distillations.It is said that this method can obtain purity and reach dicyclopentadiene more than 97%.

Chinese patent CN1490286A discloses a kind of separation method of cracked C 5 fraction, mainly on patent CN1253130A basis in conjunction with selective catalytic hydrogenation technology, carry out the extractive distillation front-end hydrogenation at carbon five and remove alkynes in the cut, saved common second section extractive distillation adopting.But because hydrogenation reaction, the saturated loss of diolefine is inevitable, and this method also must increase and faces hydrogen and hydrogen separation system simultaneously.

The principal character of CN1253130A and the disclosed method of CN1490286A is that cyclopentadiene dimerization in reaction fractionating tower becomes in the dicyclopentadiene, with the cat head feed separation that is rich in isoprene.But the residence time of material is difficult to control in the tower, also with regard to the transformation efficiency of uncontrollable cyclopentadiene, so the concentration of cat head cyclopentadiene is generally higher.The kind of stopper and consumption can directly influence reaction/condition in addition, and the engineering design difficulty that finish this method is bigger, does not also have the report of through engineering approaches at present.

In sum, all be earlier the hot dimerization of cyclopentadiene to be converted into dicyclopentadiene in the prior art, utilize the high boiling point of dicyclopentadiene to finish and the separating of isoprene then.This method can reduce the separating difficulty of isoprene and cyclopentadiene to a certain extent, but has a shortcoming: all isoprene all will be through overheated dipolymer reactor.Research and actually operating show that all isoprene has very high activity, in hot dipolymer reactor nearly 2～10% isoprene autohemagglutination or with the cyclopentadiene copolymerization, not only caused the loss of isoprene, also influence the purity of dicyclopentadiene to a great extent, reduced the use value of dicyclopentadiene.In addition, though a large amount of cyclopentadiene separates by generating dicyclopentadiene, but because isoprene is close with the cyclopentadiene boiling point, so separating energy consumption is big, and still have the cyclopentadiene of a great deal of and isoprene to enter follow-up extracting rectifying refining step jointly, influence the purity of product isoprene, cause the loss of cyclopentadiene simultaneously.

Summary of the invention

Technical problem to be solved by this invention is in the conventional art during diolefin in the separating cracked carbon-5 fraction, raw material generates dicyclopentadiene with the separating ring pentadiene through hot dipolymer reactor earlier, isoprene generation autohemagglutination and with cyclopentadiene generation copolymerization, cause isoprene and cyclopentadiene to lose in a large number; And because isoprene is close with the cyclopentadiene boiling point, be difficult to separate, the azeotropic of cyclopentadiene and other carbon five more makes separating difficulty strengthen, cause isoprene knockout tower energy consumption higher, the also higher problem of concentration of cyclopentadiene in the overhead stream simultaneously provides a kind of method of separating isoprene by combined rectification.It is little that this method has energy consumption, isoprene and the high characteristics of cyclopentadiene resolution.

For solving the problems of the technologies described above, the technical solution used in the present invention is as follows: a kind of method of separating isoprene by combined rectification may further comprise the steps:

A) carbon five materials 1 enter isoprene knockout tower 2 middle parts, and cat head separates the stream I obtain being rich in isoprene, and the tower still separates the stream I I that obtains being rich in cyclopentadiene and enters subsequent handling;

B) stream I enters cyclopentadiene recovery tower 3 middle parts, and a small amount of cyclopentadiene that is rich in the isoprene logistics is carried out Separation and Recovery, and overhead stream III enters follow-up isoprene refining step, and the tower still contains the cyclopentadiene logistics and is circulated to isoprene knockout tower 2 middle parts.

In the technique scheme, the operational condition of isoprene knockout tower 2: the stage number preferable range is 60～160, and tower still temperature preferable range is 70～110 ℃, and the tower top temperature preferable range is 35～70 ℃, the reflux ratio preferable range is 5～60, and the working pressure preferable range is 0.01～0.3MPa.The operational condition of cyclopentadiene recovery tower 3: the stage number preferable range is 60～170, tower still temperature preferable range is 55～100 ℃, the tower top temperature preferable range is 35～70 ℃, and the reflux ratio preferable range is 5～50, and the working pressure preferable range is 0.01～0.3MPa.The preferred version of step a) and step b) is that sepn process is carried out in the presence of stopper, and described stopper preferred version is to be selected from least a in ONP, tert-butyl catechol, diethyl azanol or the acid of dihydroxyl dihydro cinnamon.One of stream I preferred version is for before entering cyclopentadiene recovery tower 3, be introduced into extractive distillation column 4 middle parts, contact with the solvent that enters from tower top and to carry out extracting rectifying, cat head obtains alkane and monoolefine, and the tower still obtains being rich in the solvent base logistics VI of isoprene; Logistics VI enters stripping tower 5 and carries out solvent recuperation, and the logistics VII that cat head obtains being rich in isoprene enters step b) cyclopentadiene recovery tower 3 middle parts, and the solvent stream that the tower still obtains is back to extractive distillation column 4 tops.The operational condition of extractive distillation column 4: the stage number preferable range is 70～160, tower still temperature preferable range is 100～150 ℃, the tower top temperature preferable range is 35～80 ℃, the reflux ratio preferable range is 2～13, the working pressure preferable range is 0.01～0.3MPa, and the weight ratio preferable range of solvent and stream I is 3～11.The operational condition of stripping tower 5: the stage number preferable range is 20～60, and tower still temperature preferable range is 100～220 ℃, and the tower top temperature preferable range is 30～70 ℃, and the reflux ratio preferable range is 1～6, and the working pressure preferable range is 0.01～0.3MPa.Extracting rectifying preferred version in the extractive distillation column 4 is for to carry out in the presence of stopper, described stopper preferred version is to be selected from least a in ONP, oil of mirbane, furfural, n-formyl sarcolysine base pyrrolidone, thanomin or the Sodium Nitrite, more preferably scheme is for being selected from Sodium Nitrite and thanomin composite polymerzation inhibitor, wherein the mass ratio of Sodium Nitrite and thanomin is 0.25～15: 1, and the carbon five basic concentration of thanomin are 100～800ppm.Solvent preferred version in the extractive distillation column 4 is to be selected from least a in dimethyl formamide, N,N-DIMETHYLACETAMIDE, acetonitrile, the n-formyl sarcolysine base pyrrolidone.Two of stream I preferred version is before entering cyclopentadiene recovery tower 3, is introduced into selective hydrogenation device 6 and carries out selective hydrogenation and removing alkynes and eneyne.Selective hydrogenation device 6 reaction conditionss: the temperature of reaction preferable range is 20～80 ℃, and the reaction pressure preferable range is 0.3～1.5MPa, and liquid phase air speed preferable range is 3～20 hours ^-1The selective hydrogenation catalyst preferred version is for comprising following component by weight percentage: a) 0.1～10% be selected from least a in IB family metal or its oxide compound; B) 0.005～1% be selected from least a in VIII family metal or its oxide compound; C) 0.01～4% be selected from least a in basic metal or its oxide compound; D) alumina supporter of surplus.IB family metal preferred version is to be selected from least a in copper or the silver; More preferably scheme is the mixture that is selected from copper and silver, and wherein copper is more than 90% of IB family total metal content in the mixture.VIII family metal preferred version is for being selected from palladium.The basic metal preferred version is for being selected from potassium.

The inventive method is separated diene in the raw material C5 fraction earlier, and m-pentadiene enters the later separation flow process with cyclopentadiene to be separated, and the tower still logistics of cyclopentadiene recovery tower makes full use of in the middle part of being circulated to the isoprene knockout tower.Adopt this method, reduced the separating difficulty that causes owing to the cyclopentadiene azeotropic to a great extent, under lower energy consumption, realize the more high separation of isoprene and m-pentadiene.Isoprene autohemagglutination or copolymerization loss of 2～10% in hot dipolymer reactor in the technology before can preventing; And improve the quality product of dicyclopentadiene in carbon five devices, improve its use value.In addition, cyclopentadiene recovery tower 3 tower stills do not have any concentration control requirement, so design of cyclopentadiene recovery tower and operation easier all reduce to some extent, have obtained better technical effect.

Description of drawings

Fig. 1 is the inventive method technical process 1 synoptic diagram.

Fig. 2 is the inventive method technical process 2 synoptic diagram.

Fig. 3 is the inventive method technical process 3 synoptic diagram.

Among Fig. 1, Fig. 2 or Fig. 3,1 is carbon five materials, and 2 is the isoprene knockout tower, and 3 is the cyclopentadiene recovery tower, and 4 is extractive distillation column, and 5 is stripping tower, and 6 is the selective hydrogenation device.I is isoprene knockout tower 2 overhead streams, II is the 2 tower still logistics of isoprene knockout tower, III is cyclopentadiene recovery tower 3 overhead streams, IV is the 3 tower still logistics of cyclopentadiene recovery tower, V is extractive distillation column 4 overhead streams, VI is extractive distillation column 4 tower still logistics, and VII is stripping tower 4 overhead streams.

Technological process 1 of the present invention, carbon five materials 1 enter isoprene knockout tower 2 middle parts, and cat head separates the stream I obtain being rich in isoprene, and tower reactor is separated the stream I I that obtains being rich in cyclopentadiene and is entered subsequent handling. Stream I enters bottom in the cyclopentadiene recovery tower 3, the a small amount of cyclopentadiene that is rich in the isoprene logistics is separated recovery, cat head logistics III enters follow-up isoprene refining step, and tower reactor contains the cyclopentadiene logistics and is circulated to isoprene knockout tower 2 middle parts.

Technological process 2 of the present invention, carbon five materials 1 enter isoprene knockout tower 2 middle parts, and cat head separates the stream I obtain being rich in isoprene, and tower reactor is separated the stream I I that obtains being rich in cyclopentadiene and is entered subsequent handling. Stream I enters extractive distillation column 4 middle parts, contacts with the solvent that enters from tower top and carries out extracting rectifying, and cat head obtains alkane and monoolefine, and tower reactor obtains being rich in the solvent base logistics VI of isoprene. Logistics VI enters stripping tower 5 and carries out solvent recovery, and cat head obtains being rich in the logistics VII of isoprene, and the solvent stream that tower reactor obtains is back to extractive distillation column 4 tops and recycles. Logistics VII enters bottom in the cyclopentadiene recovery tower 3, the a small amount of cyclopentadiene that is rich in the isoprene logistics is separated recovery, cat head logistics III enters follow-up isoprene refining step, and tower reactor contains the cyclopentadiene logistics and is circulated to isoprene knockout tower 2 middle parts.

Technological process 3 of the present invention, carbon five materials 1 enter isoprene knockout tower 2 middle parts, and cat head separates the stream I obtain being rich in isoprene, and tower reactor is separated the stream I I that obtains being rich in cyclopentadiene and is entered subsequent handling. Stream I enters selective hydrogenation device 6 and carries out selective hydrogenation, takes off except behind alkynes and the eneyne, enters bottom in the cyclopentadiene recovery tower 3. Cyclopentadiene recovery tower 3 cat head logistics III enter follow-up isoprene refining step, and tower reactor contains the cyclopentadiene logistics and is circulated to isoprene knockout tower 2 middle parts.

The present invention is further elaborated below by embodiment.

Embodiment

[embodiment 1]

Press the technical process of Fig. 1, carbon five materials 1 enter isoprene knockout tower 2 by the 52nd block of column plate, and cat head separates the stream I obtain being rich in isoprene, and the tower still separates the stream I I that obtains being rich in cyclopentadiene and enters subsequent handling.Isoprene knockout tower 2 feeding temperatures are 76 ℃, and stage number is 100, and tower still temperature is 70 ℃, and tower top temperature is 44 ℃, and tower top pressure is 0.04MPa, and tower still pressure is 0.11MPa, and reflux ratio is 15.The reboiler thermal load of carbon five chargings per ton is 0.83MW.

Stream I enters cyclopentadiene recovery tower 3 by the 49th block of column plate, and a small amount of cyclopentadiene that is rich in the isoprene logistics is carried out Separation and Recovery.Overhead stream III enters follow-up isoprene refining step, and the tower still obtains cyclopentadiene, isoprene and heavy constituent and is back to the 71st column plate place of isoprene knockout tower 2.Cyclopentadiene recovery tower 3 stage number are 130, and tower still temperature is 66 ℃, and tower top temperature is 49 ℃, and tower top pressure is 0.07MPa, and tower still pressure is 0.15MPa, and reflux ratio is 7.5, and the reboiler thermal load of carbon five chargings per ton is 0.41MW.

The weight percent composition of raw material and each unit component sees Table 1.

Table 1

Component	Isoprene knockout tower 2			Cyclopentadiene recovery tower 3
							Charging	Eject material	End discharging	Charging	Eject material	End discharging
	Iso-pentane	0.55	1.07		1.07	1.21							0.00
3-methyl butene-1							0.03	0.06		0.06	0.06	0.00
	Skellysolve A	6.65	12.90		12.90	14.55							0.52
Amylene-1							3.89	7.52		7.52	8.52	0.00
	2-methyl butene-1	5.02	9.71	0.00	9.71	10.99							0.03
Anti-amylene-2							3.17	6.79	2.17	6.79	4.36	25.07
	Along amylene-2	2.17	3.42	2.76	3.42	1.46							18.18
Pentadiene-1,4							0.56	1.08	0.00	1.08	1.22	0.00
	2-methyl butene-2	3.34	4.17	5.61	4.17	0.65							30.67
Pentamethylene							1.16	0.00	2.14	0.00	0.00	0.00
	Isoprene	26.35	52.20	0.80	52.20	56.71							18.19
Cyclopentenes							4.52	0.00	8.32	0.00	0.00	0.03
	Crotonylene	0.02	0.03	0.00	0.03	0.03							0.00
Anti-pentadiene-1,3							12.21	0.00	22.49	0.00	0.00	0.01
	Along pentadiene-1,3	6.67	0.00	12.28	0.00	0.00							0.01
Cyclopentadiene							13.33	0.91	24.49	0.91	0.07	7.21
	Pentadiene-1,2	0.38	0.00	0.69	0.00	0.00							0.02
Valylene							0.07	0.13	0.00	0.13	0.15	0.00
	Total carbon six	3.31		6.09
Other heavy constituent							6.60		12.16			0.06

[embodiment 2]

Press the technical process of Fig. 2, carbon five materials 1 enter isoprene knockout tower 2 by the 55th block of column plate, the stopper ONP adds from the 10th block of column plate, and cat head separates the stream I obtain being rich in isoprene, and the tower still separates the stream I I that obtains being rich in cyclopentadiene and enters subsequent handling.Isoprene knockout tower 2 feeding temperatures are 76 ℃, and stage number is 110, and tower still temperature is 79 ℃, and tower top temperature is 55 ℃, and tower top pressure is 0.09MPa, and tower still pressure is 0.17MPa, and reflux ratio is 11.The reboiler thermal load of carbon five chargings per ton is 0.63MW.

Stream I enters extractive distillation column 4 by the 73rd block of column plate, with the 6th solvent dimethylformamide that column plate enters contacts and carries out extracting rectifying from tower top, the tower still obtains being rich in the solvent base logistics VI of isoprene, the extracting rectifying stopper is Sodium Nitrite and thanomin composite polymerzation inhibitor, wherein the mass ratio of Sodium Nitrite and thanomin is 1.4, and the carbon five basic concentration of thanomin are 400ppm.The extractive distillation column stage number is 140, and tower still temperature is 120 ℃, and tower top temperature is 43 ℃, and tower top pressure is 0.04MPa, and tower still pressure is 0.13MPa, and reflux ratio is 3.5, and solvent ratio is 5.8.

Logistics VI enters stripping tower 5 by the 20th block of column plate and carries out solvent recuperation, and cat head obtains being rich in the logistics VII of isoprene, and the solvent stream that the tower still obtains is back to the 6th column plate place, extractive distillation column 4 tops and recycles.The stripping tower stage number is 40, and tower still temperature is 169 ℃, and tower top temperature is 42 ℃, and tower top pressure is 0.03MPa, and tower still pressure is 0.05MPa, and reflux ratio is 1.3.

Logistics VII enters cyclopentadiene recovery tower 3 by the 60th column plate place, and a small amount of cyclopentadiene that is rich in the isoprene logistics is carried out Separation and Recovery, and the stopper ONP adds from the 4th block of column plate.Overhead stream III enters follow-up isoprene refining step, and the tower still obtains cyclopentadiene, isoprene and heavy constituent and is back to the 51st column plate place of isoprene knockout tower 2.Cyclopentadiene recovery tower stage number is 110, and tower still temperature is 62 ℃, and tower top temperature is 44 ℃, and tower top pressure is 0.04MPa, and tower still pressure is 0.12MPa, and reflux ratio is 9.The reboiler thermal load of carbon five chargings per ton is 0.23MW.

The weight percent composition of raw material and each unit component sees Table 2.

Table 2

Component	Isoprene knockout tower 2			Extractive distillation column 4		Stripping tower 5	Cyclopentadiene recovery tower 3
										Charging	Eject material	End discharging	Charging	Eject material	Eject material	Charging	Eject material	End discharging
	Iso-pentane	0.55	1.03	0.00	1.03	2.24
3-methyl butene-1										0.03	0.05	0.00	0.05	0.12
	Skellysolve A	6.65	12.37	0.00	12.37	26.85
Amylene-1										3.89	7.24	0.00	7.24	15.71
	2-methyl butene-1	5.02	9.35	0.00	9.35	20.28
Anti-amylene-2										3.17	5.51	0.42	5.51	11.94	0.01	0.01	0.01	0.02
	Along amylene-2	2.17	3.43	0.65	3.43	7.43	0.01	0.01	0.01										0.03
Pentadiene-1,4										0.56	1.04	0.00	1.04	2.24	0.01	0.01	0.01	0.00
	2-methyl butene-2	3.34	5.91	0.52	5.91	12.06	0.65	0.65	0.37										3.00
Pentamethylene										1.16	0.00	2.36	0.00	0.00	0.00	0.00	0.00	0.01
	Isoprene	26.35	51.35	0.80	51.35	1.13	94.28	94.28	98.95										54.36
Cyclopentenes										4.52	0.01	9.16	0.01	0.00	0.01	0.01	0.00	0.12
	Crotonylene	0.02	0.03	0.00	0.03	0.00	0.05	0.05	0.06										0.00
Anti-pentadiene-1,3										12.21	0.00	24.78	0.00		0.00	0.00	0.00	0.03
	Along pentadiene-1,3	6.67	0.00	13.54	0.00		0.01	0.01	0.00										0.08
Cyclopentadiene										13.33	2.54	26.89	2.54		4.70	4.70	0.31	42.19
	Pentadiene-1,2	0.38	0.01	0.76	0.01		0.02	0.02	0.00										0.14
Valylene										0.07	0.13	0.00	0.13		0.24	0.24	0.27	0.00
	Total carbon six	3.31		6.71
Other heavy constituent										6.60		13.40						0.01

[embodiment 3]

By the technical process of [embodiment 2], just the solvent of extracting rectifying is an acetonitrile, and the stopper of extracting rectifying is a n-formyl sarcolysine base pyrrolidone, and the stopper in stopper in the isoprene knockout tower 2 and the cyclopentadiene recovery tower is the diethyl azanol.

Each unitary operational condition sees Table 3, and the weight percent composition of raw material and each unit component sees Table 4.

Table 3

Operational condition	Isoprene knockout tower 2	Extractive distillation column 4	Stripping tower 5	Cyclopentadiene recovery tower 3
					Feeding temperature (℃)	75	-	-	-
Charging place stage number (piece)	66	46	30	52
					Total stage number (piece)	130	90	56	80
Tower still temperature (℃)	86	102	108	72
					Tower top temperature (℃)	63	54	56	63
Tower still pressure (MPa)	0.22	0.18	0.15	0.21
					Tower top pressure (MPa)	0.15	0.11	0.1	0.15
Solvent ratio	-	3.3	-	-
					Reflux ratio	8.5	9	6	20

Table 4

Component	Isoprene knockout tower 2			Extractive distillation column 4		Stripping tower 5	Cyclopentadiene recovery tower 3
										Charging	Eject material	End discharging	Charging	Eject material	Eject material	Charging	Eject material	End discharging
	Iso-pentane	0.53	0.98		0.98	2.05
3-methyl butene-1										0.03	0.05		0.05	0.11
	Skellysolve A	6.38	11.70		11.70	24.63
Amylene-1										3.74	6.85		6.85	14.42
	2-methyl butene-1	4.82	8.84	0.00	8.84	18.60	0.00	0.00	0.00
Anti-amylene-2										3.04	5.30	0.33	5.30	11.15	0.01	0.01	0.01	0.00
	Along amylene-2	2.08	3.33	0.58	3.33	6.99	0.01	0.01	0.01										0.01
Pentadiene-1,4										0.54	0.98	0.00	0.98	2.06	0.01	0.01	0.01	0.00
	2-methyl butene-2	3.35	5.83	0.37	5.83	11.51	0.88	0.88	0.29										3.50
Pentamethylene										1.12	0.00	2.45	0.00	0.00	0.00	0.00	0.00	0.02
	Isoprene	28.83	52.22	0.80	52.22	0.37	96.23	96.23	98.24										87.15
Cyclopentenes										4.34	0.02	9.51	0.02	0.00	0.02	0.02	0.00	0.12
	Crotonylene	0.01	0.03	0.00	0.03	0.00	0.04	0.04	0.05										0.00
Anti-pentadiene-1,3										11.71	0.00	25.75	0.00		0.00	0.00	0.00	0.00
	Along pentadiene-1,3	6.40	0.01	14.05	0.01		0.00	0.00	0.00										0.01
Cyclopentadiene										13.05	3.50	24.49	3.50		1.17	1.17	0.01	6.40
	Pentadiene-1,2	0.36	0.02	0.78	0.02		0.01	0.01	0.00										0.03
Valylene										0.07	0.12	0.00	0.12		0.07	0.07	0.08	0.00
	Total carbon six	3.17	0.00	6.97
Other heavy constituent										6.44	0.21	13.92	0.21	8.10	1.56	1.56	1.29	2.76

[embodiment 4]

Press the technical process of Fig. 3, carbon five materials 1 enter isoprene knockout tower 2 by the 35th block of column plate, and cat head separates the stream I obtain being rich in isoprene, and the tower still separates the stream I I that obtains being rich in cyclopentadiene and enters subsequent handling.Isoprene knockout tower 2 feeding temperatures are 40 ℃, and stage number is 80, and tower still temperature is 94 ℃, and tower top temperature is 70 ℃, and tower top pressure is 0.26MPa, and tower still pressure is 0.3MPa, and reflux ratio is 40.

Stream I enters selective hydrogenation device 6 and carries out selective hydrogenation to remove alkynes and eneyne.Selective hydrogenation device 6 reaction conditionss: temperature of reaction is 30 ℃, and reaction pressure is 0.6MPa, and the liquid phase air speed is 4 hours ^-1Wherein catalyzer each component and weight percent thereof consist of 8.5% bronze medal, 0.9% silver medal, 0.05% palladium, 2.5% potassium, 88.05% aluminum oxide.

The logistics that removes alkynes and alkene enters cyclopentadiene recovery tower 3 by the 48th block of column plate, and a small amount of cyclopentadiene that is rich in the isoprene logistics is carried out Separation and Recovery.Overhead stream III enters follow-up isoprene refining step, and the tower still obtains cyclopentadiene, isoprene and heavy constituent and is back to the 53rd column plate place of isoprene knockout tower 2.Cyclopentadiene recovery tower 3 stage number are 100, and tower still temperature is 84 ℃, and tower top temperature is 65 ℃, and tower top pressure is 0.23MPa, and tower still pressure is 0.3MPa, and reflux ratio is 26.

The weight percent composition of raw material and each unit component sees Table 5.

Table 5

Component	Isoprene knockout tower 2			Selective hydrogenation device 6		Cyclopentadiene recovery tower 3
									Raw material	Eject material	End discharging	Charging	Discharging	Charging	Eject material	End discharging
	Below carbon four reaches	3.88	6.20		6.20	7.54	7.54	9.08
Iso-pentane									3.88	6.20		6.20	6.20	6.20	7.47	0.00
	3-methyl butene-1	0.88	1.41		1.41	2.39	2.39	2.88									0.00
Skellysolve A									5.87	9.44		9.44	9.44	9.44	11.30	0.39
	Amylene-1	4.11	6.57		6.57	6.57	6.57	7.91									0.02
2-methyl butene-1									4.79	7.66	0.00	7.66	7.77	7.77	9.35	0.06
	Anti-amylene-2	2.78	6.84	2.03	6.84	6.84	6.84	3.47									23.24
Along amylene-2									1.90	3.25	3.26	3.25	3.25	3.25	0.64	15.95
	Pentadiene-1,4	2.63	4.20	0.00	4.20	4.20	4.20	5.06									0.00
2-methyl butene-2									2.93	5.09	5.86	5.09	5.09	5.09	0.22	28.78
	Pentamethylene	1.02	0.00	2.12	0.00	0.00	0.00	0.00									0.00
Isoprene									23.19	39.39	1.00	39.39	38.41	38.41	42.53	18.36
	Cyclopentenes	3.96	0.01	8.24	0.01	0.01	0.01	0.00									0.04
Crotonylene									0.84	1.34	0.00	1.34	13ppm	13ppm	16ppm	0.00
	Anti-pentadiene-1,3	10.71	0.00	22.29	0.00	0.00	0.00	0.00									0.02
Along pentadiene-1,3									5.85	0.00	12.18	0.00	0.00	0.00	0.00	0.03
	Cyclopentadiene	11.69	2.29	24.24	2.29	2.29	2.29	0.08									13.04
Pentadiene-1,2									0.33	0.01	0.69	0.01	0.01	0.01	0.00	0.05
	Valylene	0.07	0.11	0.00	0.11	6ppm	6ppm	7ppm									0.00
Total carbon six									2.90		6.04			0.00		0.00
	Other heavy constituent	5.79		12.05

[embodiment 5]

Press the technical process of Fig. 3, carbon five materials 1 enter isoprene knockout tower 2 by the 65th block of column plate, the stopper tert-butyl hydroquinone adds from the 3rd block of column plate, and cat head separates the stream I obtain being rich in isoprene, and the tower still separates the stream I I that obtains being rich in cyclopentadiene and enters subsequent handling.Isoprene knockout tower 2 feeding temperatures are 50 ℃, and stage number is 150, and tower still temperature is 73 ℃, and tower top temperature is 48 ℃, and tower top pressure is 0.06MPa, and tower still pressure is 0.14MPa, and reflux ratio is 20.

Stream I enters selective hydrogenation device 6 and carries out selective hydrogenation to remove alkynes and eneyne.Selective hydrogenation device 6 reaction conditionss: temperature of reaction is 70 ℃, and reaction pressure is 1.2MPa, and the liquid phase air speed is 16 hours ^-1Wherein catalyzer each component and weight percent thereof consist of 2.5% bronze medal, 0.01% palladium, 0.08% potassium, 97.41% aluminum oxide.

The logistics that removes alkynes and alkene enters cyclopentadiene recovery tower 3 by the 52nd block of column plate, and a small amount of cyclopentadiene that is rich in the isoprene logistics is carried out Separation and Recovery.The stopper tert-butyl hydroquinone adds from the 2nd block of column plate, and overhead stream III enters follow-up isoprene refining step, and the tower still obtains cyclopentadiene, isoprene and heavy constituent and is back to the 106th column plate place of isoprene knockout tower 2.Cyclopentadiene recovery tower 3 stage number are 140, and tower still temperature is 60 ℃, and tower top temperature is 38 ℃, and tower top pressure is 0.02MPa, and tower still pressure is 0.12MPa, and reflux ratio is 11.

The weight percent composition of raw material and each unit component sees Table 6.

Table 6

Component	Isoprene knockout tower 2			Selective hydrogenation device 6		Cyclopentadiene recovery tower 3
									Raw material	Eject material	End discharging	Charging	Discharging	Charging	Eject material	End discharging
	Iso-pentane and following	0.55	1.12	0.00	1.12	1.15	1.15	1.52									0.00
3-methyl butene-1									0.03	0.06	0.00	0.06	0.49	0.49	0.65	0.00
	Skellysolve A	6.65	14.47	0.00	14.47	14.47	14.47	17.79									4.27
Amylene-1									3.89	7.88	0.00	7.88	7.88	7.88	10.42	0.08
	2-methyl butene-1	5.02	10.24	0.00	10.24	10.38	10.38	13.62									0.41
Anti-amylene-2									3.17	7.48	3.79	7.48	7.48	7.48	2.12	23.93
	Along amylene-2	2.17	1.91	3.32	1.91	1.91	1.91	0.23									7.07
Pentadiene-1,4									0.56	1.13	0.00	1.13	1.13	1.13	1.50	0.00
	2-methyl butene-2	3.34	1.23	5.33	1.23	1.23	1.23	0.01									4.97
Pentamethylene									1.16	0.00	1.86	0.00	0.00	0.00	0.00	0.00
	Isoprene	20.27	53.97	0.90	53.97	53.54	53.54	52.13									57.87
Cyclopentenes									4.52	0.00	7.21	0.00	0.00	0.00	0.00	0.00
	Crotonylene	0.02	0.03	0.00	0.03	6ppm	6ppm	8ppm									0.00
Anti-pentadiene-1,3									12.21	0.00	19.50	0.00	0.00	0.00	0.00	0.00
	Along pentadiene-1,3	6.67	0.00	10.65	0.00	0.00	0.00	0.00									0.00
Cyclopentadiene									19.41	0.34	31.00	0.34	0.34	0.34	10ppm	1.39
	Pentadiene-1,2	0.38	0.00	0.60	0.00	0.00	0.00	0.00									0.00
Valylene									0.07	0.14	0.00	0.14	7ppm	7ppm	9ppm	0.00
	Total carbon six	3.31		5.28
Other heavy constituent									6.60		10.54

[embodiment 6]

Technical process and operational condition by [embodiment 2], just the solvent of extracting rectifying is a N,N-DIMETHYLACETAMIDE, the stopper of extracting rectifying is a furfural, and the stopper in the isoprene knockout tower 2 is the acid of dihydroxyl dihydro cinnamon, and the stopper in the cyclopentadiene recovery tower is a tert-butyl catechol; And isoprene knockout tower 2 cat head material I are before advancing extractive distillation column 3, and stream I is introduced into selective hydrogenation device 6 and carries out selective hydrogenation to remove alkynes and eneyne.Selective hydrogenation device 6 reaction conditionss: temperature of reaction is 50 ℃, and reaction pressure is 0.9MPa, and the liquid phase air speed is 9 hours ^-1Wherein catalyzer each component and weight percent thereof consist of 5% silver medal, 0.08% nickel, 1% sodium, 93.92% aluminum oxide.

Each unitary operational condition sees Table 7, and the weight percent composition of raw material and each unit component sees Table 8.

Table 7

Operational condition	Isoprene knockout tower 2	Extractive distillation column 4	Stripping tower 5	Cyclopentadiene recovery tower 3
					Feeding temperature (℃)	65	-	-	-
Charging place stage number (piece)	39	75	21	95
					Total stage number (piece)	90	150	50	140
Tower still temperature (℃)	87	150	190	75
					Tower top temperature (℃)	70	51	46	55
Tower still pressure (MPa)	0.26	0.15	0.08	0.22
					Tower top pressure (MPa)	0.21	0.08	0.05	0.1
Solvent ratio	-	8.5	-	-
					Reflux ratio	30	2.2	3	15

Table 8

Component	Isoprene knockout tower 2			Hydrogenator 6		Extractive distillation column 4		Stripping tower 5	Cyclopentadiene recovery tower 3
												Charging	Eject material	End discharging	Charging	Discharging	Charging	Eject material	Eject material	Charging	Eject material	End discharging
	Iso-pentane and following	0.16	0.33		0.33	0.34	0.34	0.64
3-methyl butene-1												0.03	0.07		0.07	0.07	0.07	0.13
	Skellysolve A	1.49	3.04		3.04	3.04	3.04	5.86
Amylene 1												6.46	13.20		13.20	13.2	13.2	25.42
	2-methyl butene-1	6.52	13.32	0.00	13.32	13.82	13.82	26.62	0.00	0.00	0.00												0.00
Anti-amylene-2												6.07	10.88	1.46	10.88	10.88	10.88	20.94	0.01	0.01	0.01	0.02
	Along amylene-2	2.84	4.00	1.73	4.00	4	4	7.69	0.01	0.01	0.00												0.02
Pentadiene-1,4												0.35	0.72	0.00	0.72	0.72	0.72	1.37	0.01	0.01	0.01	0.00
	2-methyl butene-2	3.17	4.90	1.52	4.90	6.23	6.23	11.21	0.66	0.66	0.12												4.67
Pentamethylene												0.81	0.00	1.58	0.00	0	0	0.00	0.00	0.00	0.00	0.01
	Isoprene	23?36	46.93	0.80	46.93	45.63	45.63	0.12	95.11	95.11	99.81												59.84
Cyclopentenes												4.05	0.01	7.93	0.01	0.01	0.01	0.00	0.01	0.01	0.00	0.11
	Crotonylene	0.01	0.01	0.00	0.01	10ppm	10ppm	0.00	20ppm	20ppm	22ppm												0.00
Anti-pentadiene-1,3												10.90	0.00	21.33	0.00	0	0		0.01	0.01	0.00	0.07
	Along pentadiene-1,3	6.49	0.01	12.69	0.01	0.01	0.01		0.01	0.01	0.00												0.10
Cyclopentadiene												20.88	2.06	38.89	2.06	2.06	2.06		4.18	4.18	0.05	35.12
	Pentadiene-1,2	0.11	0.00	0.21	0.00	0.00	0.00		0.00	0.00	0.00												0.04
Valylene												0.26	0.53	0.00	0.53	11ppm	11ppm		23ppm	23ppm	24ppm	0.00
	Total carbon six	6.06		11.86
Other heavy constituent												0.00		0.00

[comparative example 1]

Carbon five materials 1 enter the 46th column plate place of isoprene knockout tower 2, and cat head separates the stream I that obtains being rich in isoprene, wherein also contains monoolefine, alkane, alkynes and a spot of cyclopentadiene; The tower still is isolated the stream I I of heavy constituent such as containing cyclopentadiene, m-pentadiene.Isoprene knockout tower 2 feeding temperatures are 76 ℃, and stage number is 100, and tower still temperature is 78 ℃, and tower top temperature is 53 ℃, and tower top pressure is 0.09MPa, and tower still pressure is 0.17MPa, and reflux ratio is 30, and the reboiler of carbon five chargings per ton is 1.41MW.

The weight percent composition of raw material and each unit component sees Table 9.

Table?

Component	Isoprene knockout tower 2
				Raw material	Eject material	End discharging
	Below carbon four reaches	0.00	0.00
Iso-pentane				0.55	1.20	0.00
	3-methyl butene-1	0.03	0.06				0.00
Skellysolve A				6.65	14.37	0.00
	Amylene-1	3.89	8.41				0.00
2-methyl butene-1				5.02	10.86	0.00
	Anti-amylene-2	3.17	4.60				1.93
Along amylene-2				2.17	1.65	2.61
	Pentadiene-1,4	0.56	1.21				0.00
2-methyl butene-2				3.34	1.16	5.22
	Pentamethylene	1.16	0.00				2.17
Isoprene				26.35	56.01	0.80
	Cyclopentenes	4.52	0.00				8.41
Crotonylene				0.02	0.03	0.00
	Anti-pentadiene-1,3	12.21	0.00				22.73
Along pentadiene-1,3				6.67	0.00	12.42
	Cyclopentadiene	13.33	0.29				24.56
Pentadiene-1,2				0.38	0.00	0.70
	Valylene	0.07	0.15				0.00
Total carbon six				3.31		6.16
	Other heavy constituent	6.60					12.29

Isoprene knockout tower 2 and cyclopentadiene recovery tower 3 total reboiler are carbon five 1.24MW per ton among the embodiment 1 of same feedstock, and respective embodiments 2 is 0.86MW, and comparative example 1 is 1.41MW, has saved 12% and 38% respectively; Embodiment 1 is rich in that prenyl cyclopentadiene mass concentration is 0.30% among the isoprene material III, and respective embodiments 2 is 0.27%, and comparative example 1 is 0.53%, has reduced about 41%.Under lower energy consumption, realized the more high separation of isoprene and m-pentadiene.

Claims (10)

1. the method for a separating isoprene by combined rectification may further comprise the steps:

A) carbon five materials (1) enter isoprene knockout tower (2) middle part, and cat head separates the stream I that obtains being rich in isoprene, and the tower still separates the stream I I that obtains being rich in cyclopentadiene and enters subsequent handling;

B) stream I enters cyclopentadiene recovery tower (3) middle and lower part, the a small amount of cyclopentadiene that is rich in the isoprene logistics is carried out Separation and Recovery, overhead stream III enters follow-up isoprene refining step, and the tower still contains the cyclopentadiene logistics and is circulated to isoprene knockout tower (2) middle part.

2. according to the method for the described separating isoprene by combined rectification of claim 1, the operational condition that it is characterized in that isoprene knockout tower (2): stage number is 60～160, tower still temperature is 70～110 ℃, tower top temperature is 35～70 ℃, reflux ratio is 5～60, and working pressure is 0.01～0.3MPa; The operational condition of cyclopentadiene recovery tower (3): stage number is 60～170, and tower still temperature is 55～100 ℃, and tower top temperature is 35～70 ℃, and reflux ratio is 5～50, and working pressure is 0.01～0.3MPa; The sepn process of step a) and step b) is carried out in the presence of stopper, and described stopper is selected from least a in ONP, tert-butyl catechol, diethyl azanol or the acid of dihydroxyl dihydro cinnamon.

3. according to the method for the described separating isoprene by combined rectification of claim 1, it is characterized in that stream I is entering cyclopentadiene recovery tower (3) before, be introduced into extractive distillation column (4) middle part, contact with the solvent that enters from tower top and to carry out extracting rectifying, cat head obtains alkane and monoolefine, and the tower still obtains being rich in the solvent base logistics VI of isoprene; Logistics VI enters stripping tower (5) and carries out solvent recuperation, and the logistics VII that cat head obtains being rich in isoprene enters step b) cyclopentadiene recovery tower (3) middle part, and the solvent stream that the tower still obtains is back to extractive distillation column (4) top.

4. according to the method for the described separating isoprene by combined rectification of claim 3, the operational condition that it is characterized in that extractive distillation column (4): stage number is 70～160, tower still temperature is 100～150 ℃, tower top temperature is 35～80 ℃, reflux ratio is 2～13, working pressure is 0.01～0.3MPa, and the weight ratio of solvent and stream I is 3～11; The operational condition of stripping tower (5): stage number is 20～60, and tower still temperature is 100～220 ℃, and tower top temperature is 30～70 ℃, and reflux ratio is 1～6, and working pressure is 0.01～0.3MPa.

5. according to the method for the described separating isoprene by combined rectification of claim 3, it is characterized in that the extracting rectifying in the extractive distillation column (4) carries out in the presence of stopper, described stopper is selected from least a in ONP, oil of mirbane, furfural, n-formyl sarcolysine base pyrrolidone, thanomin or the Sodium Nitrite; Solvent in the extractive distillation column (4) is selected from least a in dimethyl formamide, N,N-DIMETHYLACETAMIDE, acetonitrile, the n-formyl sarcolysine base pyrrolidone.

6. according to the method for the described separating isoprene by combined rectification of claim 5, it is characterized in that the extracting rectifying stopper is Sodium Nitrite and thanomin composite polymerzation inhibitor, wherein the mass ratio of Sodium Nitrite and thanomin is 0.25～15: 1, and the carbon five basic concentration of thanomin are 100～800ppm.

7. according to the method for claim 1 or 3 described separating isoprene by combined rectification, it is characterized in that stream I is going out isoprene knockout tower (2) afterwards, is introduced into selective hydrogenation device (6) and carries out selective hydrogenation and removing alkynes and eneyne.

8. according to the method for the described separating isoprene by combined rectification of claim 7, it is characterized in that selective hydrogenation device (6) reaction conditions: temperature of reaction is 20～80 ℃, and reaction pressure is 0.3～1.5MPa, and the liquid phase air speed is 3～20 hours-1; Selective hydrogenation catalyst comprises following component by weight percentage:

A) 0.1～10% be selected from least a in IB family metal or its oxide compound;

B) 0.005～1% be selected from least a in VIII family metal or its oxide compound;

C) 0.01～4% be selected from least a in basic metal or its oxide compound;

D) alumina supporter of surplus.

9. the method for described separating isoprene by combined rectification according to Claim 8 is characterized in that IB family metal is selected from least a in copper or the silver; VIII family metal is selected from palladium; Basic metal is selected from potassium.

10. according to the method for the described separating isoprene by combined rectification of claim 9, it is characterized in that IB family metal is selected from the mixture of copper and silver, wherein copper is more than 90% of IB family total metal content in the mixture.

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