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
Background

The United States produces approximately
6 billion metric tons of CO2 emissions a
year.
Fig. 1: From Dr. Krothapalli’s Lecture 4 Slides for EML4450
Background
Carbon dioxide absorbs the long wave
radiation that is emitted by the earth’s
surface and reemits radiation back to the
surface.
 An overabundance of greenhouse gases
in the atmosphere can cause an increase
in Earth’s natural average temperature.

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.
Project Scope
Photodissociation of JP-8
Result:
Carbon Particulate and
Molecular Hydrogen
Separator
Hydrogen to 10HP Propulsion System
Carbon Particulate to Collector
for Recovery
Photolysis

Photolysis (also known as
photodissociation) is a method of
separating a molecule into smaller parts
using light.
Photolysis of Hydrocarbons

Photolysis of hydrocarbons can render
varying products depending on the
conditions of the environment and other
reactants involved.
 Other
hydrocarbons
 Polymers
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.
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

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.
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

Calculations
413kJ/mol divided by Avogadro’s number
gives 6.858E-22 kJ per molecular bond
 Convert to wavelength

λ
= hc/E = 290 nm
Intensity (photons/time)
 Lux (intensity/area)

 What
intensity and lux do we need?
Logistics

Lasers
 Frequencies
needed
 Purchasing and cost
 Beam size
 Multiple angles
Questions
Would multiple beams at different angles
be necessary?
 η = Po/Pi. Is this method efficient?
 What size of incident laser area is
necessary?
 Could we keep the dissociated molecules
separate?

Chemical Composition of JP-8


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


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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%
Other Addictives in JP-8
Stabilizers
 Corrosion
 Ice inhibitors
 Anti – static
 Biocides
 Gum cleaner
 Varnish cleaner

New Project Focus
Using
Hydrogen gas in an Remote
Piloted Aircraft Engine
Looking
at other
Alternative fuels for
use in I.C.E.’s
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

Flammability Ranges For Different Fuels
Look at similar
processes for use with
other alternative fuels,
such as Natural Gas,
Propane, Biodiesel,
etc.
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!!

Design Goal for Next Semester:
 Convert
a small R.P.V. (remotely piloted
vehicle) engine for use with one of the studied
fuels.
 Evaluate it’s efficiency vs. gasoline
 Determine it’s cost effectiveness
 Determine if the emissions are cleaner vs.
gasoline