hydrocarbon utilization

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