Synergistic Effect of Cold Plasma-Bimetallic Ni Co ZIF-67 as Breathable MOF System for Selective Hydrogenation of CO2 to Methanol

Plasma catalysis for CO₂ utilization technology shows considerable promise for advancement, with enhancing the synergistic relationship between plasma and catalysts being a key area of research challenge. However, current research focuses on the design of efficient catalyst formulations, but studies on metal–organic framework (MOF) screening and cold plasma methods have received less attention. Therefore, in this study, the hydrogenation of CO₂ at ambient temperature and pressure was investigated using single-metal and bimetallic ZIF-67 as a MOF catalyst with the assistance of a dielectric barrier discharge (DBD) plasma reactor. The Co ZIF-67 and Ni Co ZIF-67 were synthesized and characterized by different analytical techniques. The synergistic effects between DBD plasma and these mono- and bimetal MOFs were investigated for the transformation protocol of CO₂ to methanol. The flow rate of gas and input voltage as main parameters were screened. In this procedure, monometallic and bimetallic ZIF-67 showed 69.6 and 90.3% conversion with 84.1 and 98.1% selectivity of CH₃OH production and 2.7 and 4.8 (mmol/kJ) energy efficiency under optimized conditions (flow rate: 60 mL/min; input voltage: 10 kV). Besides, the specific input energy of the transformation as a kinetic parameter was measured and showed linear behavior. The two catalysts can be reused up to six times without significant loss of their catalytic activities.