Unveiling the Mechanism of Plasma-Catalyzed Oxidation of Methane to C<sub>2+</sub> Oxygenates over Cu/UiO-66-NH<sub>2</sub>
Chong Qi, Yifu Bi, Yaolin Wang, Hong Yu, Yuanyu Tian, Peijie Zong, Qinhua Zhang, Haonan Zhang, Mingqing Wang, Tao Xing, Mingbo Wu, Xin Tu, Wenting Wu
Abstract
High Resolution Image Download MS PowerPoint Slide Nonthermal plasma (NTP) offers the potential for converting CH 4 with CO 2 into liquid products under mild conditions, but controlling liquid selectivity and manipulating intermediate species remain significant challenges. Here, we demonstrate the effectiveness of the Cu/UiO-66-NH 2 catalyst in promising the conversion of CH 4 and CO 2 into oxygenates within a dielectric barrier discharge NTP reactor under ambient conditions. The 10% Cu/UiO-66-NH 2 catalyst achieved an impressive 53.4% overall liquid selectivity, with C 2+ oxygenates accounting for ∼60.8% of the total liquid products. In situ plasma-coupled Fourier-transform infrared spectroscopy (FTIR) suggests that Cu facilitates the cleavage of surface adsorbed COOH species (*COOH), generating *CO and enabling its migration to the surface of Cu particles. This surface-bound *CO then undergoes C–C coupling and hydrogenation, leading to ethanol production. Further analysis using CO diffuse reflection FTIR and 1 H nuclear magnetic resonance spectroscopy indicates that in situ generated surface *CO is more effective than gas-phase CO (g) in promoting C–C coupling and C 2+ liquid formation. This work provides valuable mechanistic insights into C–C coupling and C 2+ liquid production during plasma-catalytic CO 2 oxidation of CH 4 under ambient conditions. These findings hold broader implications for the rational design of more efficient catalysts for this reaction, paving the way for advancements in sustainable fuel and chemical production.