This thesis aims to provide different aspects to make the Direct Air Capture Dual Function Materials (DAC-DFM) project more applicable in commercialization and large-scale deployment to directly address the global warming problem caused by anthropogenic CO₂. Dual function materials are comprised of nano dispersed alkaline sorbents and a methanation catalyst to capture CO₂ from ambient air and convert it to CH₄ upon the addition of green H₂.
Two sub-projects named “Ru thrifting project” and “hydrophobicity/surface modification project” were performed to study the potential optimization and tradeoff when modifying the DFM components. The major accomplishment in this thesis has been the thrifting of Ru from its original value of 5% to 1% and finally 0.25% with no sacrifice in stability but with some decrease in capacity for CO₂ capture and methanation. Given the Ru unit price (around 14 USD/g, flexible market, in March 2024), this approach would greatly reduce the overall production cost. In the hydrophobicity/surface modification project, Al₂O₃ the high surface area carrier for the DFM components, was treated using 3 different methods (high temperature calcination, acid treatment, and metal oxide doping). The goal of this study was to reduce the surface water uptake in the Al₂O₃ from humidity, present in ambient air, by increasing hydrophobicity to reduce the energy evaporation cost during temperature swing in the DFM CO₂ desorption/methanation process. Samples treated after these 3 methods showed a significant decrease in water uptake. ZrO₂ doped Na₂CO₃-Al₂O₃ sample showed a low H₂O uptake and the
highest CO₂ adsorption, twice that of the CO₂ capacity of the Na₂CO₃-Al₂O₃ samples treated by calcination and acid. Such hydrophobicity study would be used to further optimize the components of DFM to meet requirements in real world applications. Future outlook for DFMs is also briefly discussed with focuses on (1) using pre-heated H₂ to increase the temperature of inner DFM coatings for increased energy efficiency, (2) increased CO₂ capture, utilization, and conversion to CH₄, as well as (3) practical acceptance of DAC hubs and CO₂ taxes/credits.
A new approach of moisture swing DAC sorbents as an alternate technology to the thermal swing DFM is suggested as a future project. With loaded CO₃²⁻ on both organic ion exchange particles/membranes and inorganic silica-based granules, the CO₂ adsorption/desorption effect can be controlled by the moisture level (relative humidity) from ambient air in the inlet sample chamber.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/khsv-pj51 |
| Date | January 2024 |
| Creators | Lin, Yuanchunyu |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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