View
52
Download
2
Category
Preview:
DESCRIPTION
Plasma Reforming of Carbon Oxides Robert Geiger, Sreekar Parami , David Staack Texas A&M, Mechanical Engineering . Hydrocarbon Utilization. CO2. Plasma Dissociation . H=393.5 kJ/mol CO2 H=241 kJ/mol H2O. CO. H2O. Combustion. Combustion Fischer Tropsch Ethanol Hydrogen. CO. H2. - PowerPoint PPT Presentation
Citation preview
Plasma Reforming of Carbon OxidesRobert Geiger, Sreekar Parami, David Staack
Texas A&M, Mechanical Engineering
Hydrocarbon Utilization
CH4 (CxHy)
• Combustion• Fischer Tropsch• Ethanol• Hydrogen
H=393.5 kJ/mol CO2H=241 kJ/mol H2O
H=110 kJ/mol CO2
CO2
H2O
CO H2
CO
1/2
Petrochemicals Higher HydrocarbonsCarbon Oxide Polymers
(Matthias Ballauff, et. al Angew. Chem. Int. Ed. 2004, 43)
Combu
stion
Partial Combustion
Upgrading
Plasma
Polymerization
Plasma Dissociation
Experimental SetupPower Supply:• Vmax ~ 10 kV• Imax ~ 40 mA• Freq ~ 25 – 30 kHz• P ~ 40W-150W
DBD Reactor
Color Variations
Deposition Rate
Increasing FlowFlow appears to change power density distribution
180 sccm 870 sccm 1700 sccm
~ 30W ~50W ~100W
Increasing PowerPower increases deposition rate and film darkness
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
Kinetic Model in Development
Still need to add• CO* reactions• C(s) reactions• Surface reactions
McTaggart FK PIasma Chemistry in Electrical Discharges (1967)
Proposed Mechanism for C3O3 Polymer Formation
Simulation
Kinetic Model of Carbon Monoxide Plasma
Emission Spectroscopy
471.5 472 472.5 473 473.5 474 474.50
0.5
1
wavelength (nm)
Inte
nsity
(A.U
.)
Trot = 408K
Tvib = 1962K
FWHM = 0.271nm
RMSE = 1.66%
ExperModel
C2 Swan Fit
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: rpg32@tamu.edu
Recommended