(455f) Integrated Direct Carbon Capture and Oxidative Dehydrogenation of Ethane with CO2 at Isothermal Conditions over Dual-Functional Adsorbent/Catalyst Composite Monoliths

Combining CO₂ adsorption and utilization in oxidative dehydrogenation of ethane (ODHE) into a single bed is an exciting way of converting a harmful greenhouse gas into marketable commodity chemicals while reducing energy requirements from two-bed processes. However, novel materials should be developed for this purpose because most adsorbents are incapable of capturing CO₂ at the temperatures required for ODHE reactions. Some progress has been made in this area; however, previously reported dual-functional materials (DFMs) have always been powdered-state composites and no efforts have been made toward forming these materials into practical contactors. In this study, we report the first-generation of structured DFM adsorbent/catalyst monoliths for combined CO₂ capture and ODHE utilization. Specifically, we formulated Cr_xV_x-CaO/ZSM-5 monoliths by 3D-printing inks with CaCO₃ (CaO precursor), insoluble metal oxides, and ZSM-5. In this study, bi-function materials (BFMs) comprising of CaO and adsorbent and bimetallic Cr_xV_x@ZSM-5 catalyst (Cr_x and V_x are the metal ratio) are synthesized and processed into 3D-structures (adsorbent-catalyst monoliths) using additive manufacturing (3D-printing technique) method. The obtained DFM adsorbent/catalyst monoliths were characterized by XPS, H₂-TPR, NH₃-TPD, TGA, BET, and EDX mapping and assessed for CO₂ capture-conversion in ODHE process. Among the developed DFMs, Cr₁V₃@ZSM-5/CaO revealed the best balance between CO₂ capture (0.74 mmol/g), C₂H₄ selectivity (42%), and syngas selectivity (45%) at 650 °C due to the bimetallic incorporation that resulted in favorable redox properties for ethane dehydrogenation/reforming to ethylene and syngas. It was also found that varying the bimetallic ratio could be utilized to control the CO₂ capture, CO₂/C₂H₆ conversion, and C₂H₄/syngas selectivity. This work establishes a promising proof of concept for structuring composite materials using a facile means such as 3D-printing and expands dual function materials to the formerly not investigated application of ODHE.

References:

1. Baamran et al., Chem. Eng. J., 2022, 435, 134706.
2. Lawson et al., Appl. Catal. B: Env 2022, 303, 120907.
3. Lawson et al., Chemical Reviews, 2021, 121, 6246-6291.