Ignition of CO2 methanation using DBD-plasma catalysis in an adiabatic reactor

In this work, a novel strategy of the use of dielectric barrier discharge (DBD) plasma-catalysis for exothermic reactions is presented. DBD-plasma is used as reaction ignitor, rather than the classical approach of continuous operation, by taking advantage of the synergy between catalytic plasma activation from room temperature and a self-sustained exothermic reaction. CO2 methanation reaction was performed in a thermal insulated reactor using an active nickel-based catalyst loaded in two catalytic bed sections, with electrodes implemented solely in the first section. DBD plasma was employed to activate the reaction from cold conditions with the subsequent increase in reactor temperature and, finally, reaction was self-sustained by thermal-catalysis. The experimental results pointed out the sensitive dependence of the reactor temperature on the gas flow rate during the plasma operation. Low-energy conditions were found in which the reaction could operate in autothermal mode, after plasma shut-off. Power and start-up time were optimized, obtaining a considerable low start-up time from cold conditions (25 ◦C) of only 3 min. Besides, the autothermal operation mode was maintained for 8 h without any energy input. This proof-of-concept work demonstrates that plasma can be implemented as initial power ignition in exothermic reactions using proper reactor design and conditions, and then, the reactor can operate in autothermal mode