investigation of deposits in a carbon monoxide dbd robert geiger advisor: dr. david staack texas...
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Investigation of Deposits in a Carbon Monoxide DBD
Robert Geiger
Advisor: Dr. David Staack
Texas A&M Mechanical Engineering
Plasma Engineering & Diagnostics Laboratory (PEDL)
Outline
• Introduction
• Experimental Setup
• Results
• Future Work
• Conclusion
Introduction
Hydrocarbon Utilization
CH4 (CxHy)
CO2
H2O
CO H2•Combustion•Fischer Troscph•Ethanol•Hydrogen•CO Polymer ?
H=393.5 kJ/mol CO2H=241 kJ/mol H2O
H=110 kJ/mol CO2
Molecular Forms of C and O
• CO
• CO2
• C3O2 Carbon Suboxide
?
(Matthias Ballauff, et. al Angew. Chem. Int. Ed. 2004, 43)
Carbon Monoxide at Really High Pressures
Lipp M J et al 2005 Nat. Mater. 4 211
V V Brazhkin 2006 J. Phys.: Condens. Matter 18 9643
EXPERIMENTAL SECTION
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
180 ccm 870 ccm 1700 ccm
~ 30W ~50W ~100W
Increasing Power
Also, gas temperature and surface temperature do not cause the different film colors.
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
•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 After
Hydration
C:O ~ 1.9 1.7
Kinetics
Proposed mechanism from several sources
McTaggart FK PIasma Chemistry in Electrical Discharges (1967)
Kinetic Model in Development
Still need to add• CO* reactions• C(s) reactions• Surface reactions
Kinetic Model in Development
Kinetic Model in Development
CO
CO2
C3O2
C3O2(p)
•Const T•Te = 1 eV•ne = 1013 cm-3
•ne = const
Emission Spectroscopy
300 350 400 450 500 550 600 650w (nm)
C2 - SPECAIRCO - Our ModelExperimental
Angstrom CO Bands (B1Σ+ – A1π)
C2 Swan Bands (d3π– a3π)
Herzberg CO Bands (C1Σ+ – A1π)
Emission Spectroscopy - Temperature
471.5 472 472.5 473 473.5 474 474.5
0
0.5
1
wavelength (nm)
Inte
nsity
(A
.U.)
Trot
= 408K
Tvib
= 1962K
FWHM = 0.271nm
RMSE = 1.66%
ExperModel
Future Work
• Determine the polymer structures (NMR) and chain length
• Characterize polymers and determine their properties
• Complete the kinetic model and compare with experimental
• Determine optimum production parameters
Conclusion
• 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
• 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
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)
Questions?
Email: rpg32@tamu.edu
Solubility and Hydration
Before After
CO CO2 + C(gr)
Metastability of CO
FTIR – Comparison with High Pressure Film
(High Pressure Film FTIR data taken from: Lipp M J et al 2005 Nat. Mater. 4 211)
500 1000 1500 2000 2500 3000 3500cm-1
High Pressure CO
High Pressure COPlasma CO Film
• C/O ratios ranging from 1.5-3.5
XPS
Ref: INSERT REF
Low Power Setting (~60W)
Color Changes with Time and Power
30 min 60 min 120min 180min
Hi Power Setting (~130W, 180 min)
Low Power Setting (~60W, 180 min)
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