Selective Hydrogenation of CO 2 From Direct Air Capture to CO Over Na‐Promoted Pt Dual‐Functional Material

Abstract CO 2 capture and reduction (CCR) to CO using dual‐functional materials (DFMs) has recently attracted significant attention as a promising strategy for carbon capture and utilization. However, most of the DFMs for CO production reported to date require high‐temperature (> 500 °C) and O 2 ‐free conditions. Herein, we used spectroscopic characterization under operating conditions for a detailed investigation of the Pt–Na/Al 2 O 3 DFM reported in our previous work that can capture CO 2 and produce CO by selective hydrogenation at moderate reaction temperatures (350 °C) in the presence of O 2 . In situ X‐ray absorption spectroscopy measurements revealed that the Pt nanoparticles of Pt–Na/Al 2 O 3 were more oxidized and electron‐deficient than those of Pt/Al 2 O 3 , even during the reduction step. In situ IR measurements confirmed that the CO and hydrogen species on Pt–Na/Al 2 O 3 desorbed at lower temperatures than those on Pt/Al 2 O 3 . In addition, modulation excitation infrared spectroscopy (ME–IR) revealed the formation of Pt–H and HCOO − intermediates. The Pt–Na/Al 2 O 3 material was used for the first time in a system integrating membrane‐based direct air capture (m–DAC) and a CCR system for CO production and showed excellent performance. CO selectivity of 93% and CO production concentrations of 1000–2500 ppm were achieved under continuous operation, demonstrating its practical applicability.