CO2 decomposition to CO in the presence of up to 50% O2 using a non-thermal plasma at atmospheric temperature and pressure

Abstract

CO2 can be converted to the more reactive species, CO and O, by non-thermal plasmas (NTPs) even in atmospheres containing significant quantities of O2. The conversion of CO2 was 15–21%, when the O2 concentration was in the range 0–20% (remainder CO2). At 20% the conversion began to decline, falling to ~10% at 50% O2. These conversions would require a few thousand K in conventional “thermal” chemistry, in the absence of a catalyst, but here they were achieved at ambient pressure and temperature. The NTP reactor used was a dielectric barrier discharge (DBD) design, packed with BaTiO3 spheres. The concentration of O2 was varied between 0 and 50% in CO2, at temperatures below 373 K and atmospheric pressure, at a residence time of 42 s. This discovery could open up new routes for direct CO2 decomposition to CO and O2, where the presence of O2 would have been assumed problematic. This “activation” of CO2 may open up a range of possible chemistries for the use and sequestration of CO2 as CO is more reactive. It may also open up opportunities for the use of CO2 as an oxidant, i.e. a source of the O radical.