Volume 45: Energy Transitions toward Carbon Neutrality: Part VIII

The influence of H2S on plasma catalysis and the conversion of CH4 and CO2 in a dielectric barrier discharge reactor for biogas reforming into syngas M. Umamaheswara Rao, Harsh Jayesh Nagda, Ch. Subrahmanyam

Abstract

Biogas is a type of sustainable energy produced by the anaerobic decomposition of organic matter derived from plants and animals. Biogas comprises significant quantities of CH4, CO2, and minor concentrations of H2S. The substance is naturally introduced into the surrounding ecosystem, with its composition exhibiting variability contingent upon its origin. The biogas reforming process was conducted in a DBD-NTP reactor, using catalysts to enhance the total reaction efficiency under ambient circumstances. Fe/γ-Al2O3, Co/γ-Al2O3, and Ni/γ-Al2O3 catalysts were synthesized by the wet impregnation method and reduced the catalyst with H2 gas in a tubular furnace. Synthesized catalysts were analyzed by XRD, BET, XPS and SEM. Prepared catalysts are integrated into a discharge zone of a DBD reactor and tested for biogas reforming reaction. The DBD plasma system produced an applied potential ranging from 16 kV to 22 kV, while maintaining a flow rate of 70 mL min-1 with a gas mixture contains CH4, CO2, and N2 at a ratio of 30:30:10. The experiment started with performing the reaction in the absence of H2S, followed by reaction with the addition of 0.054% H2S (mixed with N2), while ensuring a consistent residence duration. The data obtained from observations suggests that H2S exerts a substantial influence on the process of conversion. When H2S was added, the CH4 conversion drastically decreased from 24% (without H2S) to 15% (with H2S), and the CO2 conversion decreased from 21% to 17% at 22 kV with Ni/ γ-Al2O3 catalyst packed DBD. H2S also has an impact on energy efficiency and syngas ratio. Moreover, H2S has more impact on CH4 than CO2.

Keywords Biogas reforming, Energy efficiency, Syngas production, DBD plasma