Enhancing CO2 conversion in a temperature-controlled DBD plasma reactor with HKUST-1 catalyst: Water removal and CuO/Cu2O-derived approach

Due to a synergy effect, using dielectric barrier discharge (DBD) plasma technology combined with catalysts for CO₂ decomposition, a major contributor to global warming, is recognized as an effective approach to transforming CO₂ into valuable products such as CO, which is a crucial feedstock for chemical synthesis. Herein, HKUST-1 was synthesized using the hydrothermal method for CO₂ conversion in the DBD reactor. To enhance catalyst performance in the plasma region, HKUST-1 was treated with O₂ plasma to increase its specific surface area. Additionally, HKUST-1 was calcined at 300 °C to produce the CuO/Cu₂O catalyst. Since the recombination reaction in the CO₂ conversion is increased at higher temperatures, the reactor heat is removed using fan cooling and a water circulation system. In the presence of the HKUST-1 catalyst, the CO₂ conversion rate significantly increased by 132 %, 82 %, and 12 % in reactors operating without cooling, with fan cooling, and with water cooling circulation, respectively compared to the reactors without catalyst, at a flow rate of 50 ml/min and maximum input power. The catalysts have been characterized using a comprehensive suite of analytical techniques, including FTIR, XRD,TEM, SEM, EDS, and BET analysis. The BET analysis indicates that the specific surface area of HKUST-1 after O₂ plasma treatment is increased by 52 %, which causes an increasing conversion rate of up to 18 %. The CuO/Cu₂O catalyst demonstrated maximum CO₂ conversion of 21 % at an input power of 140 W and achieved energy efficiency of 8.6 % at 40 W. The presence of oxygen vacancies within this catalyst enhances the process of CO₂ decomposition.