isomerization processs in petroleum industry

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ISOMERIZATION PROCESS

• Basudha Maurya
• Department Of Chemical Engineering
• MNNIT, Allahabad
• vasundhre_at_gmail.com

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Presentation Outline

• Introduction
• History of Isomerization
• Feedstock Reaction Chemistry
• Isomerization Catalyst
• Isomerization Process
• Research Paper Study

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What is Petroleum?

• A complex mixture containing thousands of
  different organic hydrocarbon molecules
• 1. 83-87 Carbon
• 2. 11-15 Hydrogen
• 3. 1-6 Sulphur
• 4. .02-1.7 Nitrogen
• 5. .08-1.8 Oxygen
• 6. upto1.4 metals

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Petroleum or Crude Refining

• Separation as well as reactive process to yield
  various valuable products
• It consists
• -Unit Operation or Physical Processes
• -Unit Process or Catalytic Processes

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PHYSICAL PROCESSES

• Desalting/dehydration
• Crude distillation
• Propane deasphalting
• Solvent extraction and dewaxing
• Blending

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CATALYTIC PROCESSES

• Fluid Catalytic Cracking 
• Hydro treating
• Hydro cracking
• Catalytic Reforming
• Alkylation
• Polymerization
• Isomerization

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Generic Crude Refining Process
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Isomerization

• Isomer Compounds with the same molecular formula
  as another, but with a different structure.
• Isomerization The hydrocarbons are made into
  isomers.

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History Of Isomerization

• Developed during World War II to obtain higher
  octane gasoline.
• Initially isomerization units produced isobutane
  from n-butane using aluminum chloride.
• Today isomerization is mainly focused on the
  upgrading of re?nery naphtha(C5/C6) streams into
  high-octane motor gasoline.

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Isomerization Process In Petroleum Industry

• Isomerization Process is a
• -Fixed-bed catalytic process.
• -Conducted in vapour phase at low
  temperatures in the presence of hydrogen.
• -Using a metal hydrogenation catalyst on a
  suitable support material promoted by the
  injection of small amounts of organic chloride.
• Convert low octane number(ON) C5/C6 streams into
  high ON gasoline and C4 into i-C4

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FEEDSTOCK

• Usual feed-Light straight run naphtha (C5,C6 )
• Condensate light raf?nate from aromatic
  extraction units.
• Benzene containing feeds.

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REACTION CHEMISTRY

• Convert linear paraffin (C4 through C6) into
  their isomers.
• Reactions involved

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Conti
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Conti
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THERMODYNAMICS OF ISOMERIZATION REACTIONS

• The isomerization reaction is
• 
  
  
• - Equilibrium limited
• - Slightly exothermic
• - Slow
• - Heat of reaction is 4 to 20 kJ/mol
• - Complete conversion not achievable.
• - Long residence time is required.
• Maximum possible conversion f( reactor
  temperature).
• Thermodynamics favours lower temperatures.

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MEASUREMENT OF PERFORMANCE

• 1.Isobutane ratio (isobutane in product) / (sum
  of isobutane butane in
  product)
• 2.Butane selectivity (butanes in product) /
  (butanes in feed)
• 3.Paraf?n isomerization number (PIN) (i-pentane
  in product) / (sum of C5 in product)
• (2,2 DMB and 2,3 DMB in product) / (sum of C6
  paraf?ns in product).

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PROCESS PARAMETERS

• The extent of isomerization depends on
• -Reactor temperature,
• -Space velocity,
• -Operating pressure,
• -H2/hydrocarbon ratio.

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ISOMERIZATION CATALYSTS

• Catalyst Used
• -Chlorinated Alumina
• -Modern Zeolite
• -Metal Oxide (mainly Sulfated Zirconia)
• Basically dual functional -both metallic and
  acidic.
• - Metallic sites catalyze hydrogenation/
  
  dehydrogenation reactions.
• -Acidic sites catalyze isomerization
  hydro cracking reactions.

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Conti
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Conti
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Catalyst Activation

• Fresh isomerization catalyst is not active for
  carrying out the reactions.
• Catalyst activated by treating with some of the
  chlorinating agents such as AlCl3 or CCl4.
• Small amounts of chlorinating agent or the
  activator are also added during the operation
  cycle to maintain the catalyst activity.

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Catalyst Poisons

• Catalysts are sensitive to impurities makeup
  gas such as sulphur, nitrogen and water.
• Aromatics, ole?ns and naphthenes also act as
  poisons.

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Catalyst Regeneration

• Isomerization catalysts are prone to deactivation
  due to coke lay down on the catalyst surface by
  hydro cracking reactions.
• Activity restored by carrying out in situ
  oxidative regeneration.

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ISOMERIZATION PROCESSES BASED ON FEED

• 1. Butane isomerization
• - occurs in vapour phase.
• - Less platinum content catalyst required
  due to lower hydrogen
• uptake.
• - Isobutane product are used as feedstock
  for alkylation
• MTBE units.
• 2. C5/C6 isomerization
• -Mostly occurs in liquid phase
• -Consumes more hydrogen due to benzene
  saturation
• reactions.

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ISOMERIZATION PROCESSES BASED ON CONFIGURATION

• 1.Once-through or Single-pass isomerization
• -Only partial conversion
• -No recycle resulting in lower ON (7884)
• 2.Recycle isomerization
• -Achieve higher ON (8892)
• -For attaining higher ON, complete recycle of
  all n-paraf?ns is required.

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ISOMERIZATION PROCESS DESCRIPTION
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ISOMERIZATION REACTORS

• Carried out in trickle bed reactors
• -Feed trickles down through catalyst bed
  co-currently with H2 gas.
• Generally two reactors are used in series
  operation to complete reactions.
• -In ?rst reactor exothermic benzene saturation
  reactions occur, Temperature rise of about 1050
  deg C.
• -Second reactor is operated at temperature of
  110150 deg C.

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COMMERCIAL ISOMERIZATION PROCESSES

• 1. UOP Isomerization Processes
• (i) Butamer Process (C4)
• -Use dual functional isomerization
  catalyst.
• (ii) TIP With IsoSiv Adsorption
• -Increase the octane number by 20 units

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Conti

• (iii)Penex Process (C5/C6)
• -Isomerization of light straight run
  naphtha
• stream containing C5,C6 mixtures.
• (iv)Par-Isom Process
• -Uses a regenerable and water tolerant
• nonchlorided alumina catalyst.

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Conti

• 2.Axens Isomerization Processes
• -ON of 89 attained.
• 3. GTC Isomerization Technology
• -Platinum based mixed oxide catalyst
  system.
• 4.Axens Hexorb Isomerization Process
• -Desorbs n-paraf?ns from the molecular
  sieves by pressure swing technique.

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Conti

• 5.Shell Hysomer Process
• -Metal-loaded molecular sieve zeolite
  catalyst with high tolerance for impurities such
  as S H2O.
• 6.BP Isomerization Process
• -Utilize a ?exible Pt-alumina catalyst
  treated with CCl4.
• 7. Axens Ipsorb Isomerization Process

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CATALYTIC REFORMING VERSUS ISOMERIZATION PROCESSES

• Catalytic reforming
• -Upgrade heavy naphtha stream (C7).
• -High ON aromatics from paraf?ns
  naphthenes.
• Isomerization process
• -Upgrades light naphtha streams (C4-C6).
• -High ON isoparaf?ns from low ON n-paraf?n.

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FUTURE AREA OF WORK

• 1. Development of improved catalysts with high
  activity impurities tolerance.
• 2. Reactor developments to minimize
  maldistribution increase catalyst wetting.
• 3. Improved catalysts with high benzene
  saturation activity for minimizing benzene
  content in isomerate processing high benzene
  feedstock.

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Research Paper Study

• Development of New Isomerization
• Process for Petrochemical By-products
• ByK. Watanabe, N. Chiyoda, T. Kawakami ,Gasoline
  Production Technology Group, Research and
  Development Center, Cosmo Oil Co., Ltd., 1134-2
  Gongendo, Satte, Saitama, Japan.
• Presented at 18th Saudi Arabia-Japan Joint
  Symposium Dhahran, Saudi Arabia, November 16-17,
  2008

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Objective Of Research

• To examine the effect of catalyst, moisture
  heptane content on petrochemical(PC)-raffinate
  isomerization.
• To develop the new isomerization process with
  Pt-promoted Sulphated zirconia catalyst
  (Pt/SO42-/ZrO2) for PC-raffinate.

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Catalyst used

• Sulphated zirconia (SO42-/ZrO2) catalyst well
  known as a super solid-acid catalyst.
• Pt-promoted SO42-/ZrO2 (Pt/SO42-/ZrO2) catalyst
  shows high activity for isomerization at lower
  temperature.

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What is Petrochemical(PC)-Raffinate?

• By-product of the ethylene-cracker.
• Similar to light-naphtha main components are C6
  C7 fraction
• Not suitable for ordinary isomerization process
  because of much moisture heptane compounds.
• Low RON with a straight chain structure is a
  problem in terms of using it as a gasoline
  blend-stock.

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PC-Raffinate Light Naptha Comparison
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Formation of PC-raffinate

• Cracked gasoline obtained from naphtha cracker
  extracted to yield PC-raffinete BTX.

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Isomerization reaction of hexane

• Dominant parameter depends on catalyst type,
  content of moisture content of heptane
  fraction.

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Conti

• When n-hexane is isomerised, octane increment
  is obtained as follows
• n-hexane has only 25 RON,
• mono-branched hexane has 73 to 75 RON.
• di-branched hexane has 92 to 103 RON.

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Performance Measure

• Isomerization activity or 2,2-DMB ratio (mass )
  2,2-DMB/(all C6 compounds) 100
• Yield of C5 heavier fraction (mass )
  100-(C1C2C3C4)

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Effect of catalyst type
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Effect of moisture
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Effect of heptane fraction
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New isomerization process for PC-raffinate
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Properties of isomerated gasoline

• Isomerated gasoline is mixture of the
  isomerization product heavy raffinate (H-RFT)
  that is removed by fractionator.

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Result Obtained

• Isomerated gasoline has RON 71 while
  PC-raffinate showed only 60 RON.
• Thus octane increment is 11.
• Isomerization of the PC raffinate influences only
  the octane increment.
• Isomerated gasoline obtained is very useful
  Stable product.

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References

• 1.Dr.Ram Prasad, "Petroleum Refining Technology.
• 2.B.K Bhaskar Rao,MODERN PETROLEUM REFINING
  PROCESSES 5TH ed.
• 3. K. Watanabe, N. Chiyoda, T. Kawakami ,Gasoline
  Production Technology Group," Development of New
  Isomerization Process for Petrochemical
  By-products.
• 4. G. Valavarasu B. Sairam Corporate RD
  Centre,HPCL Light Naphtha Isomerization Process
  A Review.
• 5. M. Gopala Rao, Marshall Sittig Drydens
  Outline Of Chemical Technology 3rd ed.

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• Thank you