Graphene Produced in RF-ICP Thermal Plasma Reactor: A Ni-Catalyst Support for CO ₂ Methanation

This study investigates a methane-to-graphene-to-methane cycle as a sustainable approach for graphene synthesis and greenhouse gas mitigation. Few-layer graphene (FLG) sheets were synthesized via methane pyrolysis in an RF-ICP thermal plasma reactor and characterized using TEM, SEM, Raman spectroscopy, TGA, and BET surface area analysis. The synthesized graphene exhibited a high specific surface area and stability, enabling uniform nickel nanoparticle dispersion through wetness impregnation. The resulting Ni/graphene catalyst demonstrated strong performance in CO2 methanation. Without prereduction, 58% CO2 conversion and 74% CH4 selectivity were achieved under atmospheric pressure at a gas hourly space velocity of 12,000 mL g–1 h–1. In situ H2 reduction enhanced performance, yielding 72.5% CO2 conversion and 90% CH4 selectivity. These findings highlight graphene’s potential as an efficient catalyst support and underscore the benefits of pressure optimization for improving CO2 conversion and methane yield.