Photolysis of Hydrocarbons

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Photolysis of Hydrocarbons
FAMU-FSU College of Engineering

• Group 13 Josh Mardis, John Lubatti, Greg Smith,
  Travis Watson
• Sponsor Ken Edwards of Eglin Air Force Base

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Background

• The United States produces approximately 6
  billion metric tons of CO2 emissions a year.

Fig. 1 From Dr. Krothapallis Lecture 4 Slides
for EML4450
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Background

• Carbon dioxide absorbs the long wave radiation
  that is emitted by the earths surface and
  reemits radiation back to the surface.
• An overabundance of greenhouse gases in the
  atmosphere can cause an increase in Earths
  natural average temperature.

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Project Scope

• Design a device to dissociate jet fuel into
  carbon and molecular hydrogen to provide on
  demand hydrogen production to power a small
  propulsion system (10hp). The desired process
  for dissociation of the fuel was photolysis, as
  requested by the sponsor.
• The design should separate and collect the
  particulate so it can be recovered and sold.

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Project Scope
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Photolysis

• Photolysis (also known as photodissociation) is a
  method of separating a molecule into smaller
  parts using light.

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Photolysis of Hydrocarbons

• Photolysis of hydrocarbons can render varying
  products depending on the conditions of the
  environment and other reactants involved.
• Other hydrocarbons
• Polymers

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Photolysis of Hydrocarbons

• Once a molecule has been excited by a photon, it
  can either emit of photon, dissociate, or lead to
  other chemical processes.

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Complexities

• If the subject can be dissociated, the products
  in the mixture can react with each other,
  creating unwanted byproducts.
• Environment must be suitable that encourages
  molecular hydrogen production.
• Energy needed to dissociate the subject.
• High temperatures

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Other Methods of Hydrocarbon Dissociation

• Steam Reformation
• A large amount of hydrogen production comes from
  steam reformation of methane. Process produces
  CO2.
• Thermal Decomposition
• Requires a lot of energy.

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Specifics of Dissociation

• C-H bond has energy of approximately 413 kJ/mol
• Our objective is to break and separate
• The idea is to use a polymer that is accepting of
  the by-products leaving only molecular hydrogen

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Calculations

• 413kJ/mol divided by Avogadros number gives
  6.858E-22 kJ per molecular bond
• Convert to wavelength
• ? hc/E 290 nm
• Intensity (photons/time)
• Lux (intensity/area)
• What intensity and lux do we need?

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Logistics

• Lasers
• Frequencies needed
• Purchasing and cost
• Beam size
• Multiple angles

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Questions

• Would multiple beams at different angles be
  necessary?
• ? Po/Pi. Is this method efficient?
• What size of incident laser area is necessary?
• Could we keep the dissociated molecules separate?

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Chemical Composition of JP-8

• Isooctane ----------------------------------------
  --3.66
• Methylcyclohexane ------------------------------3.
  51
• M Xylene ---------------------------------------
  3.95
• Cyclooctane -------------------------------------
  4.54
• Decane ------------------------------------------
  16.08
• Butylbenzene -------------------------------------
  4.72
• 1,2,4,5 Tetramethylbenzene -----------------
  4.28
• Tetralin -----------------------------------------
  -- 4.14
• Dodecane ---------------------------------------
  22.54
• 1 Methylnaphthalene -------------------------
  3.49
• Tetradecane ------------------------------------
  16.87
• Hexadecane ------------------------------------
  12.22

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Other Addictives in JP-8

• Stabilizers
• Corrosion
• Ice inhibitors
• Anti static
• Biocides
• Gum cleaner
• Varnish cleaner

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New Project Focus

• Using Hydrogen gas in an Remote Piloted Aircraft
  Engine

• Looking at other Alternative fuels for use in
  I.C.E.s

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Things To Focus On

• Feasibility of converting a traditional R.P.A.
  Engine for Hydrogen use.
• Determine the Processes involved
  in the Conversion

LA Series OS RC Aircraft Engine
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• Look at similar processes for use with other
  alternative fuels, such as Natural Gas, Propane,
  Biodiesel, etc.

Flammability Ranges For Different Fuels
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• Look at the safety issues involved with using
  these fuels in an I.C.E.
• Do a Benefits analysis for these fuels
  vs. Gasoline

Emphasis On Safety!!
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• Design Goal for Next Semester
• Convert a small R.P.V. (remotely piloted vehicle)
  engine for use with one of the studied fuels.
• Evaluate its efficiency vs. gasoline
• Determine its cost effectiveness
• Determine if the emissions are cleaner vs.
  gasoline

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