Study of Gaseous and Solid Carbon-based Byproducts during the Plasmolysis of Hydrocarbons in a Gliding Arc Discharge Reactor

Because of its "warm" characteristics—which result from its ability to bridge the gap between cold and thermal plasmas—gliding arc discharge (GAD) is widely considered an effective gas conversion technique. Additionally, GAD has a number of benefits over other plasma techniques, such as the ability to operate at atmospheric pressure, great versatility, and impressive efficiency for a range of conversion processes. Significantly lower thermodynamic demands than water electrolysis make plasma-assisted hydrocarbon decomposition a promising method for producing H₂, and GAD is well suited for this process. Hydrogen and carbon-based byproducts are produced during this process by the breakdown of hydrocarbon feedstocks such as methane and propane. However, exhaustive data on the formation of gaseous and solid carbonaceous by-products under GAD conditions - especially in the absence of catalysts or oxygen - are still limited. [1-3].

In this work, we aim to contribute to the understanding of the generation of carbon-based byproducts in Ar/CH₄ and Ar/C₃H₈ plasmas generated at atmospheric pressure in a two-dimensional gliding arc reactor [4-5]. Using Fourier-transform infrared spectroscopy (FTIR) and gas chromatography (GC), we methodically investigate the effects of total gas flow rate, hydrocarbon concentration, and discharge current on gas conversion efficiency and carbon-based byproducts selectivity. Specifically, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD) are used to characterize the morphology and structure of the resultant solid carbon materials. The significance of a thorough and comparative examination of plasma-assisted conversion processes involving these two hydrocarbon feedstocks is highlighted by our findings.