Gas-phase and On-surface Chemical Reduction of CO2 to HCHO and CO under Dielectric Barrier Discharge

Abstract

Selective chemical reduction of CO2(g) (with carrier Ar) in presence of organic compounds, either mixed in the gas-phase or present as a contact surface, under Dielectric Barrier Discharge is presented in this study. Along with gas-phase CO generation, added hydrocarbons (C n H 2n+x ; n = 6–12; x = 0 or 2) resulted in HCHO production with the maximum H-atom utilization efficiency being ∼15% of the total present. Product CO and HCHO were estimated separately by pre-concentration in specific absorber solutions followed by their discrete colorimetric measurements. On the other hand, in presence of various types of organic surfaces (e.g. wax, plastics and polymers, also acting simultaneously as a dielectric barrier), it was found that while CO could be estimated as above, in the ensuing chemical conversion, product HCHO was retained on these surfaces. On leaching the HCHO into the absorber solution, its production efficiency was estimated to be ∼5% of CO2.