(526h) In-Line Spectroscopic Monitoring of Catalytic Reactions in Non-Thermal Plasma Reactor

Current environmental challenges demand advancements in industrial processes, particularly through innovative recycling methods and energy consumption reduction. Plasma-based technologies, especially non-thermal plasmas, have attracted attention for their potential to drive catalytic reactions for energy production and sustainable products. Non-thermal plasmas are of great interest due to their ability to achieve performances at lower temperatures and pressures with minimal energy input, making them promising for environmentally friendly applications.

In this study, we investigated non-thermal plasma technology for CO2 hydrogenation and methane dry reforming reactions using various online spectroscopic techniques to understand the reaction mechanisms. Reactions were conducted in a non-thermal microwave plasma reactor at atmospheric pressure. Plasma generation was monitored using optical emission spectroscopy (OES), and solid catalysts were characterized by diffuse reflectance Fourier transform infrared spectroscopy (DRIFT). Gaseous products were analyzed using a residual gas analyzer (RGA).

CO2 hydrogenation was studied with Ar as a carrier gas, CO2, and H2 at varying ratios, gas hourly space velocity (GHSV), and microwave power. A Nickel-ZrO2 catalyst with Hydroxyapatite (HAp) was used to enhance CO2 conversion and CO selectivity. Dry reforming of methane was conducted with Ar, CO2, and CH4, testing two catalysts: a Nickel-based catalyst with HAp and one made from mining residues.

Real-time monitoring with OES showed plasma stabilization, FTIR spectroscopy tracked catalyst consumption, and RGA identified the formed compounds throughout the reactions. The combination of these techniques enabled the identification of preferential reaction pathways for CO2 hydrogenation and methane dry reforming. These insights can contribute to optimizing plasma-based processes for sustainable industrial applications.