Plasma Reforming of Carbon Oxides
Robert Geiger, Sreekar Parami, David Staack
Texas A&M, Mechanical Engineering
Hydrocarbon Utilization
CO2
H=393.5 kJ/mol CO2
H=241 kJ/mol H2O
H2O
H=110 kJ/mol CO2
CO
CH4 (CxHy)
Partial Combustion
1/2
H2
Plasma
Dissociation
CO
•Combustion
•Fischer Tropsch
•Ethanol
•Hydrogen
Carbon Oxide Polymers
Petrochemicals
Higher Hydrocarbons
(Matthias Ballauff, et. al Angew. Chem. Int. Ed. 2004, 43)
Experimental Setup
Power Supply:
•Vmax ~ 10 kV
•Imax ~ 40 mA
•Freq ~ 25 – 30 kHz
•P ~ 40W-150W
DBD Reactor
Color Variations
Deposition Rate
Increasing Flow
Flow appears to change power density distribution
180 sccm
870 sccm
1700 sccm
Gas temperature and surface temperature do not cause the
different film colors.
Increasing Power
Power increases deposition rate and film darkness
~ 30W
~50W
~100W
FTIR – Comparison with High Pressure Film
(High Pressure Film FTIR data taken from: Lipp M J et al 2005 Nat. Mater. 4 211)
Film Properties
Hydration
•C:O ~ 1.5 - 3.5 (XPS)
•Solubility
•Water (Hydrates)
•Insoluble
•Acetone
•Ethanol
Solubility allows for spin coating
and layer by layer film growth
Before
C:O ~ 1.9
After
1.7
Kinetic Model in Development
Proposed Mechanism for C3O3 Polymer Formation
Kinetic Model of Carbon Monoxide Plasma
McTaggart FK PIasma Chemistry in Electrical Discharges (1967)
Simulation
Still need to add
•
CO* reactions
•
C(s) reactions
•
Surface reactions
Emission Spectroscopy
C2 Swan Fit
T
rot
Exper
Model
= 408K
Tvib = 1962K
FWHM = 0.271nm
RMSE = 1.66%
Intensity (A.U.)
1
0.5
0
471.5 472 472.5 473 473.5 474 474.5
wavelength (nm)
Future Work
• CO Plasma
–
–
–
–
–
Determine the polymer structures (NMR) and chain length
Characterize polymers and determine their properties
Energy Balances
Complete the kinetic model and compare with experimental
Determine optimum production parameters
• CO2 Plasma
– Optical Emmsion for gas temperature and temperature
gradients
– Optimize systems
•
•
•
•
Residence times
Surface to volume ratios
Specific input power
Power supply efficiencies
– Compare Systems
Conclusion
• CO Plasma
– Interesting films can be formed as fast as 1 mg/min at 50W
with solely carbon and oxygen atoms
– These films appear similar in structure to high pressure CO
polymers not C3O2
– Increased power darkens the film and increases deposition
rate
– Color changes do not alter the FTIR
– A kinetic model in under development
– The C2 swan, CO angstrom and CO Herzberg bands
enables temperature measurements in the visible range
• CO2 Plasma
– Micro-glow discharge showed best results
– High power density and rapid quenching are thought to be
desirable
References
• Lipp M J et al 2005 Nat. Mater. 4 211
• V V Brazhkin 2006 J. Phys.: Condens. Matter 18 9643
• McTaggart FK PIasma Chemistry in Electrical Discharges
(1967)
• P.C.Cosby, J. Chem. Phys. 98,9560(1993).
• K.M.D’Amico,and A.L.S.Smith, J.Phys.D: Appl. Phys. 10,261
(1977)
Email: [email protected]