Additively-Manufactured, Net-Shape Adsorbent Beds for Carbon Dioxide Removal

Current and future human space exploration missions require an optimized air revitalization system (ARS) that can reduce the system mass, volume, and power, and also increase reliability. The ARS systems contain a carbon dioxide reduction assembly (CDRA) that is adsorbent-based and is limited in performance because commercially-available packed bed sorbent materials are used. Hierarchical (meso, macro, micro porosity) zeolite-based, monolithic adsorbent beds (MAB) for CO2 removal were designed and modeled using computational fluid dynamics (CFD). Over 13 different adsorbent test lattice designs were evaluated for pressure drop (?P) and surface area to volume ratio (A/V). CFD modeling results show two designs that offer a significant improvement in both A/V ratio and ?P over a packed bed. The MAB were 3D-printed using an aluminosilicate (geopolymer) to bind commercially-available zeolite X13 particles together (3DZeoGeo). The aluminosilicate binder was cured via chemical reaction at low-temperatures, ranging from room temperature (RT) to 400 �C. Proof-of-concept (POC) 3DZeoGeo paste formulations, mixing methods, and 3D-printing on modified commercially-available systems and curing processes were developed and demonstrated for producing MAB. 3D-printed monoliths with zeolite loadings as high as 94 wt % were fabricated and characterized for robustness, mechanical properties, pressure drop, and CO2 removal efficiency. 3D-printed monolithic zeolite adsorbent beds have the potential to be drop-in replacements for existing packed adsorbent beds with improved mass transfer, heat transfer, and mechanical robustness properties. The new 3DZeoGeo process demonstrated improved 3D-printing processes and paste formulations which have the potential to increase the technology readiness level (TRL) of 3D-printing processes for producing net-shape, monolithic sorbent beds as drop-in replacements for packed sorbent beds such as those in the CDRA.