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)