Electric-field-controlled energy barrier and reaction pathway ensure high sulfur product selectivity in Cu/γ-Al2O3 catalyst-assisted DBD plasma conversion of carbonyl sulfide

Abstract

Carbonyl sulfide (COS) is a major organic pollutant causing atmospheric aerosols, however, current removal technologies fail to meet the efficiency and by-product selectivity requirements. Here we address this issue by utilizing dielectric barrier discharge (DBD) plasma catalysis which combines the high reaction activity of a plasma and the high reaction selectivity of a catalyst. In this study, we investigated the conversion of carbonyl sulfide (COS) using a combination of dielectric barrier discharge (DBD) and a Cu/γ-Al2O3 catalyst, comparing it with the conversion achieved through thermal catalysis and DBD alone. The removal efficiency of COS reached 98.9% at 4.5 kJ/L with no gaseous sulfur byproduct (H2S and SO2) generated at the first 4 hours when COS was treated by DBD combined with Cu/γ-Al2O3. The CuO on the Cu/γ-Al2O3 catalyst is converted to Cu2S and CuS upon reacting with COS. According to the density functional theory calculations, the reaction energy barrier can be controlled by the electric field. The cycle reaction with the thus reduced energy barrier between Cu2S, CuS, and COS enhanced selective plasma-catalytic conversion of COS to sulfur. The outcomes contribute to the development of advanced plasma-electrified catalytic technologies for environmental remediation.