WO2003059504A2 - Procede de regeneration de tamis moleculaires - Google Patents

Procede de regeneration de tamis moleculaires Download PDF

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Publication number
WO2003059504A2
WO2003059504A2 PCT/EP2003/000239 EP0300239W WO03059504A2 WO 2003059504 A2 WO2003059504 A2 WO 2003059504A2 EP 0300239 W EP0300239 W EP 0300239W WO 03059504 A2 WO03059504 A2 WO 03059504A2
Authority
WO
WIPO (PCT)
Prior art keywords
molecular sieve
process according
regeneration
nitrogen
hydrocarbons
Prior art date
Application number
PCT/EP2003/000239
Other languages
English (en)
Other versions
WO2003059504A3 (fr
Inventor
Werner Webers
Thomas Urban
Michael Dettmer
Original Assignee
Sasol Germany Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sasol Germany Gmbh filed Critical Sasol Germany Gmbh
Priority to AU2003235714A priority Critical patent/AU2003235714A1/en
Publication of WO2003059504A2 publication Critical patent/WO2003059504A2/fr
Publication of WO2003059504A3 publication Critical patent/WO2003059504A3/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/34—Regenerating or reactivating
    • B01J20/3483—Regenerating or reactivating by thermal treatment not covered by groups B01J20/3441 - B01J20/3475, e.g. by heating or cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/34—Regenerating or reactivating
    • B01J20/3408—Regenerating or reactivating of aluminosilicate molecular sieves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/34—Regenerating or reactivating
    • B01J20/345—Regenerating or reactivating using a particular desorbing compound or mixture
    • B01J20/3458—Regenerating or reactivating using a particular desorbing compound or mixture in the gas phase
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
    • C07C7/12—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
    • C07C7/13—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers by molecular-sieve technique

Definitions

  • the present invention relates to a process for regenerating molecular sieves in adsorber columns employed in Olex plants for producing high-purity lower alkenes.
  • Alkenes can be separated from alkanes by adsorption/ desorption methods utilising molecular sieves for selectively separating the desired component (cf. Ruthven, Douglas M., Principles of Adsorption and Adsorption Processes, 1984, p. 396-405).
  • the molecular sieves thus also adsorb traces of water, oxygen-containing compounds, or nitrogen- and sulphur compounds besides the alkanes and alkenes to be separated from each other. These components are largely separated from the feedstock in upstream multistage distillation facilities. The remainders are nevertheless adsorbed by the molecular sieve and cannot be eliminated at the operating conditions.
  • molecular sieves may act as catalysts, thus allowing alkenes for example to dimerise or oligomerise on the molecular sieve surface. These higher oligomers, too, cannot be eliminated at the operating conditions.
  • the molecular sieve capacity (selective pore volume) will decrease by 52.8 % after 1,521 operating days. During this period the butenes yield decreases to 80 % of its initial value.
  • the term 'yield' is defined as the ratio of butenes quantity in the extract to butenes quantity in the feed.
  • the n-butenes yield decreases annually, namely from 100 % to 97 in the first year, from 97 % to 94 in the second, from 94 % to 90 in the third, from 90 % to 85 in the fourth, and from 85 % to 80 in the fifth. Therefore, the molecular sieve filling must be exchanged at regular intervals.
  • the molecular sieve in the facility described hereinabove is usually exchanged for a fresh filling at about five-year intervals. During this exchange the production stands still. The molecular sieve exchange thus involves idle time of more than 50 production days.
  • U.S. Patent 4,935,400 to Amoco discloses the separation of COS and H 2 S from C 3 -hydrocarbons using molecular sieves. These sieves then are regenerated by means of gaseous hydrocarbons heated to approx. 315 °C at 68 mbar such that the respective sulphur components vaporize and are desorbed from the molecular sieve.
  • This regeneration method is especially employed in processes for obtaining long-chain n-paraffins from refinery streams using molecular sieves.
  • U.S. Patent 3,451,924 to Shell describes a process for separating alkanes from refinery streams.
  • the coke compounds are periodically burnt off from the contaminated molecular sieve in a nitrogen stream containing approx. 1 % oxygen.
  • U.S. Patent 5,043,517 to Mobil Oil discloses a continuous process for oligomerizing C 2 - to C 4 -alkenes on zeolitic catalysts.
  • the polymers formed as undesired by-products deposit on the molecular sieve surface.
  • part of the catalyst is continually removed from the reactor and transferred to a stripper, wherein the catalyst is freed from residual low-boiling components by means of an inert gas stream.
  • the polymers then are burnt in an airflow at approx. 500 °C.
  • all prior art processes involve the elimination of high-boiling or least volatile impurities from molecular sieves by burning with oxygen. Burning with oxygen requires high regeneration temperatures of greater than 280 °C involving either discharging the adsorbent from the adsorber column or having same excellently equipped.
  • thermal regeneration of oligomer-bearing molecular sieves is not believed to be feasible because the desorption of COS alone, which has a boiling point of -50 °C, requires temperatures of approx. 300 °C.
  • an object of this invention to develop a molecular sieve regenerating process which avoids the disadvantages described hereinabove and improves the economics of the separation technique, increases the molecular sieve lifetime, reduces the idle time when exchanging the molecular sieve, and increases the average product yield.
  • the subject matter of the invention is a process for regenerating molecular sieves used for the separation of alkanes having 3 to 6 carbon atoms, preferably 3 or 4, from alkenes having 3 to 6 carbon atoms, preferably 3 or 4, by removing long-chain oligomeric hydrocarbons and/or compounds containing oxygen, nitrogen, or sulphur, particularly long-chain oligomeric hydrocarbons, wherein at temperatures of from 200 to 280 °C, preferably 210 to 240 °C, nitrogen as an inert stripping gas is passed preferably downwardly through a column filled with a molecular sieve and the ratio of the total volume of inert gas to the volume of molecular sieve ranges from 1,000 : 1 to 20,000 : 1, preferably 4,000 ⁇ : 1 to 8,000 : 1 (the gas volume has been converted on
  • the stripping gas is preferably free from oxygen ( ⁇ 50 ppm).
  • Long-chain oligomeric hydrocarbons are for example those having a distillation range of greater than 300 °C at 1,013 mbar. Further preferred embodiments of the process of the invention are set out in the subordinate claims.
  • hydrocarbons can be removed from the molecular sieve by stripping with a carrier gas at temperatures of as low as 210 to 240 °C already.
  • the oligomers thereby are neither burnt nor cracked, but are removed instead from selective pores merely by the vapour pressure and the carrier gas volume.
  • the long-chain oligomers of the distillation range stated hereinabove can be quantitatively removed in a relatively short period of time already. Maximum activity of the molecular sieve is reached even after repeated adsorption/desorption cycles.
  • n-butenes are separated from n-butane by the moving-bed method. Adsorption takes place on zeolites (UOP's ADS 32) at approx. 80 °C and a pressure of 10 bar.
  • the individual adsorber beds packed with zeolites are controlled by a special system such that the adsorber tower is.partitioned into four sections, thus making a continuous process possible (cf. Fig. 3).
  • section 1 the n-butenes are adsorbed in selective pores.
  • n-butane is desorbed by the adsorber and discharged as raffinate.
  • section 3 the adsorbed n-butenes are finally desorbed and discharged as extract.
  • section 4 which functions as a buffer between sections
  • the desorbent is partially desorbed.
  • the desorbent of choice is a mixture of n- hexane and 1-hexene.
  • the terms used in the examples refer to the flow sheet illustrating an embodiment of the process of the invention.
  • oligomers During the service time of 1,521 days long-chain oligomers had formed on the molecular sieve surface and in the pores. These oligomers which have a crystalline structure as proved by an electron microscope inhibit the active sites of molecular sieves. The amount of carbon on the molecular sieve was found to be 9.5 %. The BET surface decreased from 515 m 2 /gram to 66 m 2 /gram. In order to remove the adherent oligomers, the molecular sieve was regenerated in an apparatus like the one depicted in Fig. 1.
  • the capacity reached 84 %, referring to a new molecular sieve, the amount of carbon on the surface decreased to 2 %, ⁇ and-79 % of the oligomers were removed.
  • the BET surface was 450 mVgram, i.e. 87.4 % of the original molecular sieve.
  • butane/butene is displaced both from the void space in the reactor and the interstitial volume of the molecular sieve by nitrogen purge.
  • Butane/butene adsorbed in the molecular sieve pores is desorbed by a hexane/ hexene mixture and then is analysed.
  • the desorbed butene quantity indicates the capacity of the molecular sieve under examination in comparison with a new molecular sieve employed in a test run.
  • Example 2 In the same apparatus, the molecular sieve utilised in Example 2 was treated for 100 hours with n-hexane vapour at 240 °C. The flow rate was 20 grams/hour, i.e. 5.2 Nl/hour. After regeneration, a capacity of 84.2 % was attained.
  • the molecular sieve capacity decreased to 82.1 % and the n-butene yield dropped to 92.5 % after 785 operating days.
  • the regeneration was carried out by downwardly displacing the olefins and C 6 -hydrocarbons first by n-butane, then by a nitrogen stream. Thereafter the adsorber column was heated with nitrogen having a temperature of approx. 100 °C. The flow rate ranged from 1,500 to 2,000 m 3 /h. The pressure at the top of the adsorber column was in the range of from approx. 1 to 2 bar. During 24 hours the temperature of the nitrogen stream was raised to approx. 250 °C.
  • the temperatures in the upper, middle, and lower sections of the adsorber column were about 230 °C, 223 °C, and 215 °C, respectively. After 72 hours at these temperatures no hydrocarbons were detected in the nitrogen effluent from the adsorber column. After the regeneration the molecular sieve capacity increased to 96.3 %. The n-butene yield reached 99 wt.% again.
  • the same molecular sieve was regenerated again under the same conditions.
  • the regenerated molecular sieve had a capacity of 95.1 %.
  • the olefin yield was as high as 98.5 wt.%.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Water Supply & Treatment (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé de régénération de tamis moléculaires dans des colonnes absorbantes employées par exemple dans des usines Olex pour produire des alcènes de faible poids moléculaire. La régénération est effectuée par désorption au moyen d'un gaz porteur.
PCT/EP2003/000239 2002-01-15 2003-01-13 Procede de regeneration de tamis moleculaires WO2003059504A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003235714A AU2003235714A1 (en) 2002-01-15 2003-01-13 Molecular sieve regenerating process

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10201260.1 2002-01-15
DE2002101260 DE10201260C1 (de) 2002-01-15 2002-01-15 Verfahren zur Regeneration von Molekularsieben

Publications (2)

Publication Number Publication Date
WO2003059504A2 true WO2003059504A2 (fr) 2003-07-24
WO2003059504A3 WO2003059504A3 (fr) 2004-03-11

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PCT/EP2003/000239 WO2003059504A2 (fr) 2002-01-15 2003-01-13 Procede de regeneration de tamis moleculaires

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AU (1) AU2003235714A1 (fr)
DE (1) DE10201260C1 (fr)
WO (1) WO2003059504A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110548364A (zh) * 2019-10-17 2019-12-10 清远先导材料有限公司 一种回收分子筛吸附的特种气体的方法和装置

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107790112B (zh) * 2016-08-30 2020-08-07 中国石油化工股份有限公司 用于脱除低碳烯烃中含氧化合物吸附剂的活化方法
CN107774239B (zh) * 2016-08-30 2020-08-07 中国石油化工股份有限公司 用于脱除低碳烯烃中含氧化合物吸附剂的再生方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3075023A (en) * 1959-09-14 1963-01-22 Universal Oil Prod Co Restoration of the activity of inorganic sorbents
DE1190444B (de) * 1957-04-26 1965-04-08 Exxon Research Engineering Co Verfahren zum Regenerieren eines Molekuelsieb-Adsorptionsmittels
CH473606A (de) * 1962-09-12 1969-06-15 Exxon Research Engineering Co Verfahren zur Regenerierung von Adsorbentien ohne Abbrennen
US6106702A (en) * 1998-12-29 2000-08-22 Uop Llc Olefinic hydrocarbon separation process

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3451924A (en) * 1967-12-28 1969-06-24 Shell Oil Co N-paraffin separation process
US4899016A (en) * 1988-02-11 1990-02-06 Uop Purification process for organic feedstocks
US4935400A (en) * 1988-10-12 1990-06-19 Amoco Corporation Reduction of hydrocarbon losses in a molecular sieve hydrocarbon treating system
US5043517A (en) * 1989-10-30 1991-08-27 Mobil Oil Corporation Upgrading light olefin fuel gas in a fluidized bed catalyst reactor and regeneration of the catalyst

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1190444B (de) * 1957-04-26 1965-04-08 Exxon Research Engineering Co Verfahren zum Regenerieren eines Molekuelsieb-Adsorptionsmittels
US3075023A (en) * 1959-09-14 1963-01-22 Universal Oil Prod Co Restoration of the activity of inorganic sorbents
CH473606A (de) * 1962-09-12 1969-06-15 Exxon Research Engineering Co Verfahren zur Regenerierung von Adsorbentien ohne Abbrennen
US6106702A (en) * 1998-12-29 2000-08-22 Uop Llc Olefinic hydrocarbon separation process

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110548364A (zh) * 2019-10-17 2019-12-10 清远先导材料有限公司 一种回收分子筛吸附的特种气体的方法和装置

Also Published As

Publication number Publication date
AU2003235714A8 (en) 2003-07-30
WO2003059504A3 (fr) 2004-03-11
AU2003235714A1 (en) 2003-07-30
DE10201260C1 (de) 2003-03-06

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