CO2 conversion promoted by potassium intercalated g-C3N4 catalyst in DBD plasma system

• CO 2 conversion can be promoted by K intercalated g-C 3 N 4 catalyst in DBD plasma system. • Decreasing reactor temperature can inhibit the reverse reaction of CO 2 conversion. • 20.6% of energy efficiency was obtained in KuCN/AO filled DBD plasma system. • Rich surface structure of KuCN/AO facilitated the adsorption and decomposition of CO 2 . • K intercalation adjusted the band structure of g-C 3 N 4 and improved CO 2 conversion. The direct conversion of CO 2 to CO and O 2 has attracted extensive attention as CO is a key C1 feedstock for chemical synthesis. The CO 2 conversion promoted by γ-Al 2 O 3 supported potassium intercalated g-C 3 N 4 (KuCN/AO) catalyst in a packed-bed dielectric barrier discharge (DBD) plasma system was investigated. A coaxial cylinder DBD plasma reactor was used with Cu powder as the high voltage electrode. Reactor temperature showed converse effect on CO 2 conversion. As the reactor temperature decreased from 120 ℃ to 50 ℃, CO 2 conversion rate and energy efficiency both increased by ca. 50%. After the catalyst was filled into the discharge area, the discharge mode changed from filamentary discharge to the combination of filamentary-surface discharge. The morphology and structure of KuCN was characterized by SEM, XRD, FTIR and XPS. KuCN kept a porous structure and K element distributed uniformly between CN interlayer spacing. In KuCN/AO assisted DBD plasma system, the highest CO 2 conversion rate, CO yield and energy efficiency were increased from 11.1%, 10.0% and 9.41% to 19.3%, 18.1% and 20.6% compared with pure DBD/γ-Al 2 O 3 system, respectively. The main mechanism of KuCN assisted enhancing CO 2 conversion in packed-bed DBD reactor was analyzed. The larger specific surface area, layers bridging and charge redistribution enabled KuCN/AO to obtain good plasma-catalytic CO 2 conversion performance.