Discharge characteristics and ozone generation during CO2 to CO conversion by dielectric barrier discharge packed with TiO2-coated glass beads

A packed-bed dielectric barrier discharge was used to investigate CO 2 to CO conversion under different operating conditions as frequency, CO 2 /Ar gas mixture composition and gas flow rate, to understand the effects of their variations on current–voltage discharge characteristics, CO 2 to CO conversion ratios, CO yields, and ozone production. Using TiO 2 -coated glass beads has changed the discharge behavior from the glow mode to a combined filamentary and surface discharge mode, making the discharge more diffuse for higher frequencies in the range of 3.6 to 6 kHz. Higher CO 2 to CO conversion and CO yield are achieved by lowering both operating frequencies and CO 2 concentrations in CO 2 /Ar gas mixture. For TiO 2 -coated glass beads packed discharge, increasing discharge frequency from 3.6 to 6 kHz lower CO 2 conversion from 11.2% to 2.5%, while increasing CO 2 concentrations in CO 2 /Ar gas mixture from 10 to 40% lowers conversion from 11.2% to 5%. The enhancement of ozone production by the introduction of TiO 2 -coated glass beads packing material may be related to improvements of conversion ratio from CO 2 to CO and CO yield showing their larger values at lower frequencies and lower CO 2 percentages in CO 2 /Ar gas mixture. Using inexpensive and easily synthesized in large quantities catalyst material, realized by TiO 2 coating of glass beads in a microwave plasma torch, has permitted to reach DBD operational modes adequate for CO production in moderate concentrations suitable for applications in medicine and agriculture. Graphical abstract