CN104030874A - Process for separating n-butene and isobutene based on carbon molecular sieve adsorption - Google Patents
Process for separating n-butene and isobutene based on carbon molecular sieve adsorption Download PDFInfo
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- CN104030874A CN104030874A CN201410273735.1A CN201410273735A CN104030874A CN 104030874 A CN104030874 A CN 104030874A CN 201410273735 A CN201410273735 A CN 201410273735A CN 104030874 A CN104030874 A CN 104030874A
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Abstract
The invention relates to a process for separating n-butene and isobutene based on carbon molecular sieve adsorption. According to the process, a carbon molecular sieve of which the pores are adjusted is adopted as an adsorbent, and based on a non-balance adsorption effect, the carbon molecular sieve is very high in adsorption selectivity for n-butene and isobutene. The process comprises the following steps: introducing a n-butene and isobutene mixed gas into an adsorption tower with the pore-adjusted carbon molecular sieve, and effectively adsorbing n-butene by using a three-tower or multi-tower variable pressure adsorption technique through a non-balance effect, wherein isobutene of which the purity is 99-99.5% can be obtained at a discharge hole; achieving high-purity and high-yield separation of n-isobutene through a replacement step. By adopting the process, a n-butene and isobutene mixed system can be separated in an adsorption manner so as to obtain high-purity n-butene and isobutene components, and thus the utilization rate of n-butene and isobutene in C-4 fraction is improved.
Description
Technical field
The invention belongs to gas adsorption separation technology field, relate to a kind of technique based on the positive isomery butylene of carbon molecular sieve fractionation by adsorption, carbon molecular sieve through toning hole aligns isomery butylene Molecular Geometries and has very high adsorption selectivity, by the pressure-swing adsorption process with displacement step, positive isomery butylene is carried out to effective separation, thereby obtain highly purified n-butene and iso-butylene product.
Background technology
In petrochemical production process, be conventionally accompanied by the generation of positive isomery hydrocarbon mixture.Because boiling point and the volatility of quite a few positive isomery hydro carbons are very approaching, cause and be difficult to by its separation completely, therefore generally only as fuel combustion, caused the significant wastage of resource.More typical example is the mixed c 4 cut from refinery catalytic cracking unit and chemical plant ethylene cracker, because boiling point and the relative volatility of n-butene wherein and iso-butylene are very approaching, n-butene boiling point is-6.250 ℃, iso-butylene boiling point is-6.896 ℃, and relative volatility only differs 0.005, therefore be difficult to, with traditional rectificating method, it is carried out to separation.
At present, the utilization ratio of China's carbon four aspect chemical industry only has 10% left and right, and the utilization ratio of industrially developed country's carbon four resources such as the U.S., Japan and West Europe has reached 60 ~ 90%, and the utilization ratio level of visible China carbon four also lags far behind developed country.How to make full use of n-butene and iso-butylene in carbon four resources, separating-purifying goes out highly purified n-butene and iso-butylene, the high value added products such as the valeral of being badly in need of in producing country, amylalcohol, improve the economic benefit of enterprise, have become the problem of people's extensive concern.
Iso-butylene mainly contains sulfuric acid extraction process, resin hydration evaporation, methyl tertiary butyl ether (MTBE) cracking process and adsorption method of separation at industrial separation method.The separating technology of n-butene mainly contains the NPC technology of German Kruup Uhde technology, Japanese auspicious father-in-law's technique, Japan petroleum chemical company, the IFP isolation technique of France and the UOP isolation technique of the U.S..
Sulfuric acid extraction process is the industrial iso-butylene partition method adopting the earliest, and it is to utilize the difference of n-butene, iso-butylene and sulfuric acid reaction speed to realize separated object.Iso-butylene and sulfuric acid generation esterification generate the sulfuric acid tert-butyl ester, and the sulfuric acid tert-butyl ester is hydrolyzed and generates the trimethyl carbinol, and trimethyl carbinol dehydration generates iso-butylene, and then the iso-butylene that is greater than 99% through alkali cleaning, washing, compression and refining acquisition purity.
Methyl tertiary butyl ether method is under liquid-phase condition, adopt macropore strong acid ion exchange resin to make catalyzer, C-4-fraction and methyl alcohol containing iso-butylene carry out selective reaction production methyl tertiary butyl ether (MTBE), the etherification procedure of iso-butylene and methyl alcohol carries out with electrophilic addition mechanism, then MTBE again cracking generate iso-butylene.
Cation exchange resin is under the effect of Zeo-karb, and iso-butylene catalytic hydration generates the trimethyl carbinol.Okumura etc. have studied a kind of method that the trimethyl carbinol is produced in serialization, adopting small-particle ion exchange resin is catalyzer, bed resistance is large, flow direction of material is after C-4-fraction mixes with water and stream, upper entering and lower leaving, once, by whole reactor, reaction product concentration is little, and isobutene conversion is only 40% ~ 50%.
Dense heteropolyacid hydration method is by add heteropolyacid catalyst in carbon-4, makes the hydration of selective isobutene ground produce the trimethyl carbinol, realizes the separated of iso-butylene and n-butene.Due to the complicacy of reaction system itself, only have up to now one, toray company to realize the industrialization of heteropolyacid hydration method.
Adsorption method of separation is that on molecular sieve, the difference of adsorptive power realizes separated Technology according to n-butene and pib molecule shape and big or small difference.At present, the Aromax method of the Parex Fa He toray company (Toray) of UOP (UOP) is two large mainstream technologys of adsorption method of separation, and all adopts zeolite molecular sieve as sorbent material.
The auspicious father-in-law's technique of Japan: Nippon Zeon Co., Ltd. has developed take polar solvent as extraction agent distillation technique.Material carbon four is introduced in extractive distillation column, through separation of extractive distillation, become butene fraction and butane cut, butylene and solvent mixture are through entering at the bottom of tower in stripping tower, butylene and separated from solvent in stripping tower, butylene steams and enters rectifying tower from tower top, separated n-butene and 2-butylene in rectifying tower, then obtain highly purified n-butene product through extracting rectifying.
The Kruup Uhde technology of Germany: this technology is usingd morpholine and N-methylmorpholine mixture and extracted as extraction agent, and the advantage of this technology is the selectivity of n-butene high, and solvability is better, the yield of product can reach 95%, and the flow process of the method is simple, number of devices is less, and energy consumption is low.
The NPC technology of Japan petroleum chemical company: 4 column distillation series of Japan petroleum Chemical Co., Ltd. exploitation form the n-butene system that reclaims, and wherein front 2 tower serial operations, remove the Trimethylmethane carbon elimination four from tower top.With discharging at the bottom of the tower of front 2 distillation towers, it is raw materials recovery n-butene.Purity is greater than 99%, and the rate of recovery can reach 96%.But because the relative volatility of normal butane and n-butene is very approaching, be only 1.10, therefore need the rectifying tower of 140 polylith theoretical trays, required energy consumption is higher.
The IFP isolation technique of France: the technical process that conventional distillation of IFP's employing and one-time extractive rectification combine can obtain highly purified n-butene product from extraction distillation solvent recovery tower tower top.
UOP isolation technique: Uop Inc. has proposed to utilize physical method for separation mixed c 4, with the technical process of high-purity n-butene.Uop Inc. adopts Sorbutene technique, and with the simulation moving-bed production n-butene with rotary valve, the purity of n-butene product is greater than 97%, and the rate of recovery can reach 88%.
Summary of the invention
The object of the invention is to propose a kind of technique based on the positive isomery butylene of carbon molecular sieve fractionation by adsorption, carbon molecular sieve through toning hole aligns isomery butylene Molecular Geometries and has high selectivity, utilize non-equilibrium adsorption effect separating mechanism, employing is with the absorbing process flow process of displacement step, make n-butene enrichment on the sorbent material in fixing adsorption tower, realize the object of outlet enrichment iso-butylene; By n-butene, replace, obtain the yield of highly purified n-butene and raising iso-butylene, thereby realize effective separation of positive isomery butylene in C-4-fraction, improve the utilization ratio of resource and realize the protection to environment.
The technical solution used in the present invention is as follows:
The technique based on the positive isomery butylene of carbon molecular sieve fractionation by adsorption that the present invention proposes, the charcoal base adsorbent that the carbon molecular sieve adopting is close hydrocarbon, its adsorption separation process has been taken into account kinetics of adsorption effect and steric effect simultaneously, the main aperture of material is controlled at 0.5 ~ 0.6nm, and adopt by three towers or multitower pressure-variable adsorption separating technology, can obtain highly purified n-butene and iso-butylene component, purity to 99% ~ 99.5%.Concrete steps are as follows:
(1) carbon molecular sieve through toning hole is packed in each adsorption tower;
(2) the positive isomery butylene of unstripped gas gas mixture is pressurizeed through compressor, and under constant pressure, send into the 1st adsorption tower and adsorb, controlling the 1st adsorption tower internal adsorption pressure is 0.3 ~ 1MPa, adsorption temp is 60 ~ 100 ℃, the direct enrichment iso-butylene in exit of the 1st adsorption tower, its purity is greater than 99%, and n-butene is collected by vacuum pump;
(3) n adsorption tower replaced and vacuum pumping, all the other are the 2nd, 3 years old ... the individual adsorption tower of n-1 (n >=3) carries out step-down or equal press operation;
(4) when the 1st adsorption tower adsorbed, n adsorption tower vacuumizes and stops, and the 1st adsorption tower starts n adsorption tower all press or the 1st adsorption tower carried out to reduced pressure operation, thereby improves iso-butylene yield;
(5) the part n-butene that adopts n-butene or a upper loop cycle to collect carries out replacement operator to the 1st adsorption tower, residual iso-butylene in the 1st adsorption tower is replaced away, displacement gas iso-butylene returns in unstripped gas n-butene and iso-butylene mixed gas, now n-1 adsorption tower is carried out gas product fast pressurization and enters absorption phase;
(6) utilize the method for vacuum pump suction to carry out vacuum desorption to the 1st adsorption tower, control desorption pressures is 0 ~ 0.08MPa, and outlet obtains highly purified n-butene, purity 96%; , the n-butene major part in exit is as product, and a small amount of n-butene has been used for the displacement of next loop cycle;
(7) so far, the 1st adsorption tower completed an absorption-desorption and regeneration process, and preparing boosts again carries out next one circulation.
The present invention is with respect to the zeolite adsorbent of Uop Inc., the charcoal base adsorbent that the sorbent material adopting is close hydrocarbon, and its adsorption separation process has been taken into account kinetics of adsorption effect and steric effect simultaneously, and the main aperture of material is controlled at 0.5 ~ 0.6nm.Because carbon molecular sieve is nonpolar sorbing material, with respect to zeolite molecular sieve, can not form stronger chemical bond with alkene, so vacuum desorption can be realized good regeneration effect, improve the processing efficiency to raw material.
The displacement desorption agent that the absorbing process that the present invention proposes adopts is n-butene, but is not limited to this kind of strippant.
Accompanying drawing explanation
Fig. 1 is the three tower pressure-changing process flow figure that the present invention adjusts the separated positive isomery butylene of hole carbon molecular sieve.
Number in the figure: 1 is the first adsorption tower, 2 is the second adsorption tower, and 3 is the 3rd adsorption tower, and 4 is compressor, and 5 is vacuum pump.
Embodiment
Below by embodiment, the present invention is described in further details.
The present invention adopts three towers or multitower pressure swing adsorption technique, and the cyclical operation process by absorption, all pressure (step-down), displacements, desorb, pressurising, realizes enrichment n-butene on sorbent material, and adsorption tower exports the object of direct enrichment iso-butylene.
By adjusting the carbon molecular sieve in hole to be packed in adsorption tower, pass into n-butene and iso-butylene mixed gas, the iso-butylene that exports direct enrichment is directly collected; After absorption finishes, adopt n-butene to carry out replacement operator to adsorption tower, the iso-butylene in sorbent material hole is replaced, promote the concentration of n-butene in adsorption tower.Finally adsorption tower is carried out to vacuum desorption, the n-butene major part in exit is as product, and a small amount of n-butene has been used for the displacement of next cycle.For guaranteeing the continuity of product output, can adopt three towers or multitower pressure swing adsorption technique.
In above-mentioned steps, adsorption tower internal pressure is controlled at 0.3 ~ 1MPa, and temperature is controlled within the scope of 60 ~ 100 ℃.
The n-butene purity >96% obtaining by above-mentioned processing method, the purity >99% of iso-butylene.
Embodiment 1
Adsorption tower adopts three tower absorption, and positive isomery butylene gas mixture (n-butene 50%, iso-butylene 50%), in the adsorption tower that 156kg/ tower carbon molecular sieve is housed is sent in overdraft, is forced into 0.5MPa, and in tower, temperature is controlled at 80 ℃.Positive isomery butylene gas mixture enters the first adsorption tower 1 and adsorbs, and absorption simultaneously the second adsorption tower 2 is all pressed and finally boosted, and the 3rd adsorption tower 3 is all pressed, bled off pressure, displacement and vacuum pumping.When the first adsorption tower 1 has adsorbed, the 3rd adsorption tower 3 vacuumizes and stops.The first 1 pair of adsorption tower the 3rd adsorption tower 3 is all pressed, and the second adsorption tower 2 enters adsorption process simultaneously.After all pressing, the first adsorption tower 1 enters forward and bleeds off pressure, and now the 3rd adsorption tower 3 is carried out to gas product and finally boosts.The first adsorption tower 1 bleeds off pressure after end, enters replacement process and vacuum desorption.Sequential control is: adsorb 300 seconds, all press 60 seconds, pressurising 240 seconds, forward bleeds off pressure 30 seconds, replaces vacuum desorption 30 seconds 180 seconds.So cyclical operation, the purity 96% ~ 97% of n-butene after pressure-variable adsorption, yield is 95.5%; The purity 99% ~ 99.5% of iso-butylene, yield is 98.8%.
Embodiment 2
Adsorption tower adopts three tower absorption, and positive isomery butylene gas mixture (iso-butylene 99%, n-butene 1%), in the adsorption tower that 310kg/ tower carbon molecular sieve is housed is sent in overdraft, is forced into 0.3MPa, and in tower, temperature is controlled at 60 ℃.Positive isomery butylene gas mixture enters the first adsorption tower 1 and adsorbs, and absorption simultaneously the second adsorption tower 2 is all pressed and finally boosted, and the 3rd adsorption tower 3 is all pressed, bled off pressure, displacement and vacuum pumping.When the first adsorption tower 1 has adsorbed, the 3rd adsorption tower 3 vacuumizes and stops.The first adsorption tower 1 carries out reduced pressure operation, and the second adsorption tower 2 enters adsorption process simultaneously.After step-down, the first adsorption tower 1 enters forward and bleeds off pressure, and now the 3rd adsorption tower 3 is carried out to gas product and finally boosts.The first adsorption tower 1 bleeds off pressure after end, enters replacement process and vacuum desorption.Sequential control is: adsorbs 600 seconds, and step-down 120 seconds, pressurising 480 seconds, forward bleeds off pressure 60 seconds, replaces vacuum desorption 60 seconds 360 seconds.So cyclical operation, the purity 99.9% ~ 99.99% of iso-butylene after pressure-variable adsorption, yield is greater than 98%.
The above-mentioned description to embodiment is can understand and apply the invention for the ease of those skilled in the art.Person skilled in the art obviously can easily make various modifications to these embodiment, and the General Principle of explanation is again applied in other embodiments and needn't passes through performing creative labour.Therefore, the invention is not restricted to the embodiment here, those skilled in the art are according to announcement of the present invention, and the improvement of making for the present invention and modification all should be within protection scope of the present invention.
Claims (1)
1. the technique based on the positive isomery butylene of carbon molecular sieve fractionation by adsorption, the charcoal base adsorbent that the carbon molecular sieve that it is characterized in that employing is close hydrocarbon, its adsorption separation process has been taken into account kinetics of adsorption effect and steric effect simultaneously, the main aperture of material is controlled at 0.5 ~ 0.6nm, and adopt three towers or multitower pressure-variable adsorption separating technology, obtain highly purified n-butene and iso-butylene component, purity to 99% ~ 99.5%; Concrete technology step is as follows:
(1) using the carbon molecular sieve through toning hole as sorbent material, be packed in each adsorption tower;
(2) the positive isomery butylene of unstripped gas gas mixture is pressurizeed through compressor, and under constant pressure, send into the 1st adsorption tower and adsorb, controlling the 1st adsorption tower internal adsorption pressure is 0.3 ~ 1MPa, adsorption temp is 60 ~ 100 ℃, the direct enrichment iso-butylene in exit of the 1st adsorption tower, its purity is greater than 99%, and n-butene is collected by vacuum pump;
(3) n adsorption tower replaced and vacuum pumping, all the other are the 2nd, 3 years old ... the individual adsorption tower of n-1 (n >=3) carries out step-down or equal press operation;
(4) when the 1st adsorption tower adsorbed, n adsorption tower vacuumizes and stops, and the 1st adsorption tower starts n adsorption tower all press or the 1st adsorption tower carried out to reduced pressure operation, thereby improves iso-butylene yield;
(5) the part n-butene that adopts n-butene or a upper loop cycle to collect carries out replacement operator to the 1st adsorption tower, residual iso-butylene in the 1st adsorption tower is replaced away, displacement gas iso-butylene returns in unstripped gas n-butene and iso-butylene mixed gas, now n-1 adsorption tower is carried out gas product fast pressurization and enters absorption phase;
(6) utilize the method for vacuum pump suction to carry out vacuum desorption to the 1st adsorption tower, control desorption pressures is 0 ~ 0.08MPa, and outlet obtains highly purified n-butene, purity 96%; , the n-butene major part in exit is as product, and a small amount of n-butene has been used for the displacement of next loop cycle;
(7) so far, the 1st adsorption tower completed an absorption-desorption and regeneration process, and preparing boosts again carries out next one circulation.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112657461A (en) * | 2019-10-15 | 2021-04-16 | 中国石油化工股份有限公司 | N-butene adsorbent and preparation method and application thereof |
| CN113474317A (en) * | 2018-12-18 | 2021-10-01 | 沙特基础工业全球技术公司 | Separation of olefinic components from mixtures of butanes and butenes using rectification and adsorbents |
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| CN101993329A (en) * | 2010-10-18 | 2011-03-30 | 天津市泰旭物流有限公司 | Technique for preparing butene by adopting molecular sieve adsorption method for purification in gas phase state |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101993329A (en) * | 2010-10-18 | 2011-03-30 | 天津市泰旭物流有限公司 | Technique for preparing butene by adopting molecular sieve adsorption method for purification in gas phase state |
Non-Patent Citations (2)
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| 戚寅 等: "炭分子筛的孔径分布研究", 《上海化工》 * |
| 翟宇恺 等: "炭质吸附剂的孔结构修饰及表征", 《应用化工》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113474317A (en) * | 2018-12-18 | 2021-10-01 | 沙特基础工业全球技术公司 | Separation of olefinic components from mixtures of butanes and butenes using rectification and adsorbents |
| CN112657461A (en) * | 2019-10-15 | 2021-04-16 | 中国石油化工股份有限公司 | N-butene adsorbent and preparation method and application thereof |
| CN112657461B (en) * | 2019-10-15 | 2024-03-26 | 中国石油化工股份有限公司 | N-butene adsorbent and preparation method and application thereof |
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