The Oligomerization of 1Butene A New Approach To Full Performance Jet Fuels

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The Oligomerization of 1-Butene A New Approach
To Full Performance Jet Fuels

• Benjamin G. Harvey, Michael E. Wright, Roxanne
  Quintana
• Naval Air Warfare Center Weapons Division
• China Lake, CA

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Ridgecrest
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Ridgecrest
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Outline

• Introduction
• 1st and 2nd generation biofuels, cellulosic
  butanol as a feedstock
• Jet fuel requirements JP-8, JP-5
• Background
• Olefin oligomerization SHOP, Sasol, acidic
  catalysts
• Ziegler-Natta Catalysis, Cp2ZrCl2, MAO
• Our Approach
• Methods
• Product distributions, physical properties
• Utilization of dimer fraction
• Conclusions

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First Generation Biofuels

• Ethanol from Sugar or Starch (Sugar Cane and
  Beets, Corn)
• Proven Technology
• Energy IntensiveUse of Fossil Fuels
• Use of Corn in US drives up food costs,
• Ethanol has a low energy density compared to
  gasoline

• Biodiesel (Fatty Acid Methyl EsterFAME)
• Established technology, fuel produced by
  esterification of triglycerides
• Similar performance to Diesel 2
• Low energy yield per acre based on typical
  sources such as soybeans
• High melting point, ca. -5 C

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2nd Generation Biofuels

• Butanol from Cellulose
• Higher energy density than ethanol, gt85 that of
  gasoline
• Less hygroscopic than ethanolphase separates
  with water
• Can be used as a major component of diesel fuel
• Is non-competitive with food sources

• Biodiesel from Algae
• Ca. 150 times higher yield per acre compared to
  soybeans
• Requires a concentrated CO2 source
• Similar properties to conventional biodiesel
• Potential Scale-up issues

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Biobutanol Synthesis From Glucose
1. Ramey, D. US Patent 5753474 1998
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Production of Fuels from Cellulose
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Jet Fuel Requirements

• Energy Density
• JP-8, JP-5 ca. 42 MJ/kgaromatics
• Fully saturated hydrocarbon ca. 44 MJ/kg
• Flash Point
• JP-8 (38 C), JP-5 (60 C)
• Density Requirement (0.78 g/mL)
• Cold Flow Properties ( Viscosity _at_ -20 C)
• JP-8 (8.0 cSt), JP-5 (8.5 cSt)

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Oligomerization of Olefins

• Shell Higher Olefin Process (Ni based)conversion
  of ethylene to mid-range olefins (primarily
  linear)
• Sasol (ethylene trimerization)
• Acidic zeolites
• Mesoporous aluminosilicates
• Supported nickel catalysts

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Ziegler-Natta Catalysis

• Kaminsky showed that butene could be oligomerized
  by Zirconocene/MAO catalysts.1 Reactions
  performed in toluene, with highest yields of
  trimer/tetramer at an Al/Zr ratio of ca. 100
• Highly regioselective1,2-addition
• Slightly elevated temperatures and slow flow
  rates required for effective oligomerization
• Broad oligomer distribution
• Bergmann showed that using one equivalent of MAO
  led to production of only dimer for a variety of
  primary olefins.2
• Low TON
• High catalyst loadings

• Kaminsky, W. Macromol. Symp. 1995, 89, 203.
• Christoffers, J. Bergman, R. G. Inorg. Chim.
  Acta 1998, 270, 20

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Ziegler Natta Catalysis
ß-hydride elimination is in competition with
olefin insertion. Product distribution is
dependent on charge separation and ligand
environment
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Methods

• Batch Catalysis in a Sealed Bomb
• Reaction and work-up require no solvent
• AlZr ratio of 1001
• Autogenous pressure of 1-butene
• No external heating
• TON of gt17,000
• Complete Conversion of 1-butene
• 230 g scale
• gt98 yield

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Oligomer Mixture
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Hydrogenation of Oligomers

• PtO2 Utilized as the hydrogenation catalyst
• TON of gt1000
• No external heating
• Reaction carried out at 2 psig H2 (mercury
  bubbler)
• Colloidal platinum flocculates upon completion of
  the reaction

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NMR Spectra of Olefin Mixture and the
Hydrogenated Mixture
Butene Oligomers
Hydrogenated Oligomers
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Catalyst Preparation--Results

• Method 1
• Isolated solid catalyst
• Catalyst loaded in a glove box
• Ca. 28 mass dimer
• Density without dimer is 0.79 g/ml
• Distillation up to 360 C yields 89 distillate

• Method 2
• Slurried catalyst (3-methyl-heptane)
• Can be carried out on a Schlenk line
• Ca. 40 mass dimer
• Density without dimer is 0.78 g/ml
• Distillation up to 313 C yields 99
  distillatein effect, no high temp. distillation
  is required.

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Fuel Properties

• Method 1
• Dimer removed, no high temp. distillation
• Flash Point 59 C
• Viscosity 103 cSt (-20 C)
• Lubricity 0.45 mm
• Freezing point lt -60 C
• EA 85 C, 15 H

• Method 2
• Flash Point 58 C
• Viscosity 12.3 cSt (dimer removed, no high
  temp. distillation)
• Lubricity 0.60 mm
• Freezing point lt -60 C

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C8 Utilization

• Blendingeffect on viscosity, flashpoint
• Use as a gasoline range fuel
• Dimerization (acid catalysis)

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Dimer Blends
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Acid Dimerization of 2-ethyl-1-hexene
Highly acidic catalysts are required due to the
poor nucleophilicity of the olefin Yields are
high, gt95, however some cracking reactions also
occur
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Gas ChromatogramH2SO4 dimerized 2-ethyl-1-hexene
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Key Points

• A high yield process has been developed to
  produce fully saturated hydrocarbon fuel
  candidates from 1-butene, a renewable fuel
  through 1-butanol.
• Removal of dimer produces a JP-5 equivalent fuel,
  while back addition of dimer can be used to
  custom tailor the fuels physical properties such
  as viscosity and flash point.
• The dimer can be easily converted to a mixture of
  C15-C17 molecules that can be incorporated into
  high flashpoint fuel mixtures.
• The unique ethyl branching of the fuel components
  allows for incorporation of longer chain
  oligomers which improves both the fuel density
  and lubricity values.

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Acknowledgements

• China Lake NAWCWD--Funding
• Dr. Michael E. Wright
• Roxanne Quintana