Reactive Capture and Conversion of CO into Hydrogen over Bifunctional Structured CeCoNiO/Ca Perovskite-Type Oxide Monoliths.

Carbon capture, utilization, and storage (CCUS) technologies are pivotal for transitioning to a net-zero economy by 2050. In particular, conversion of captured CO to marketable chemicals and fuels appears to be a sustainable approach to not only curb greenhouse emissions but also transform wastes like CO into useful products through storage of renewable energy in chemical bonds. Bifunctional materials (BFMs) composed of adsorbents and catalysts have shown promise in reactive capture and conversion of CO at high temperatures. In this study, we extend the application of 3D printing technology to formulate a novel set of BFMs composed of CaO and CeCoNiO perovskite-type oxide catalysts for the dual-purpose use of capturing CO and reforming CH for H production. Three honeycomb monoliths composed of equal amounts of adsorbent and catalyst constituents with varied CeCo ratios were 3D printed to assess the role of cobalt on catalytic properties and overall performance. The samples were vigorously characterized using X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), N physisorption, X-ray photoelectron spectroscopy (XPS), H-TPR, CO adsorption/desorption XRD, and NH-TPD. Results showed that the CeCo ratios- = 0.25, 0.50, and 0.75-did not affect crystallinity, texture, or metal dispersion. However, a higher cobalt content reduced reducibility, CO adsorption/desorption reversibility, and oxygen species availability. Assessing the structured BFM monoliths via combined CO capture and CH reforming in the temperature range 500-700 °C revealed that such differences in physiochemical properties lowered H and CO yields at higher cobalt loading, leading to best catalytic performance in CeCoNiO/Ca sample that achieved 77% CO conversion, 94% CH conversion, 61% H yield, and 2.30 H/CO ratio at 700 °C. The stability of this BFM was assessed across five adsorption/reaction cycles, showing only marginal losses in the H/CO yield. Thus, these findings successfully expand the use of 3D printing to unexplored perovskite-based BFMs and demonstrate an important proof-of-concept for their use in combined CO capture and utilization in H production processes.