Electrochemical CO <sub>2</sub> Valorization Pathways and Processes toward C <sub>2</sub> to C <sub>6</sub> Products: Acetylene, Propylene, Butadiene, and Benzene
Jorge V Ferreira de Araujo, Jan Rossmeisl, Hanqing Yin, Xingli Wang, Alexander Bagger, Peter Strasser
Abstract
High Resolution Image Download MS PowerPoint Slide CO 2 electrolysis on Cu catalysts at near-ambient conditions yields a range of important C 1 to C 3 products. Despite recent advances, our mechanistic understanding of the CO 2 electrolysis reaction network has remained incomplete, with C 4 products, and in particular long sought-after aromatic C 6 product molecules, still being elusive. Here, we use a real-time capillary DEMS technique to determine the kinetic onset potentials of a wide set of C 1–3 CO 2 reduction products. Included in our study are rarely reported products, such as propionaldehyde, propylene, and, first, acetylene, C 2 H 2 . We then focus on the formation of acetylene, C 2 H 2, and also investigate its alkyne electro-reduction, the C 2 H 2 reduction reaction (C 2 H 2 RR). Acetylene electrodimerizes to the C 4 compound 1,3-butadiene in a 2e – reduction reaction. It also revealed a potential-dependent electroless Cu-catalyzed ambient-condition [2 + 2 + 2] cycloaddition reaction to C 6 benzene. We discuss mechanisms and the significance of the potential-dependent valorizations of acetylene on Cu. We hypothesize a future process concept to valorize CO 2 into sustainable C 6 e-aromatics.