Non-thermal plasma catalysis for low temperature CO2 hydrogenation

This study investigates non-thermal plasma (NTP) as a high-efficiency alternative for low-temperature CO2 methanation, providing a systematic comparison of γAl2O3 supported Ni, Ru/Rh, and Rh/Ru catalysts in a dielectric barrier discharge reactor. While plasma alone yields minimal conversion, strong plasma–catalyst synergy triggers methane formation at only ⁓50 °C with >90% selectivity. The bimetallic Ru/Rh catalyst demonstrates clear superiority, achieving an exceptional 97% CO2 conversion at just 190 °C—a drastic reduction compared to conventional 300-500 °C thermal regimes. The quantitative modelling via a modified Arrhenius approach, proves a three-fold reduction in apparent activation energy (from 60 to 70 to 18-20 kJ/mol). Furthermore, through optimized reaction heat retention, the system achieved 95.1% conversion at a record low Specific Energy Input of 2.2 kJ/L. These findings, corroborated by in operando Optical Emission Spectroscopy, position bimetallic plasma-catalysis as a highly viable, energy-efficient solution for decentralized Power-to-Gas applications.