(508d) Continuous Wire 3D Printed Sorbent Structures – Evaluation of CO2 Capture Enhancement

Traditional adsorbent columns using pelletized media represents a mature technology with high packing density, low-cost, and simple replacement, however they suffer from high pressure drop, mechanical attrition of the media, and poor heat transfer resulting in a slow thermal response for thermal swing adsorption (TSA) applications. For thermally limited processes, 3D printed sorbent structures offer the potential to provide drastic performance improvements as they enable precisely tailored geometry with an interconnected thermal network with high lateral contact and precise control of channel geometry and controlled flow mixing which can overcome diffusion limitations within the bed. Mainstream has further enhanced these process benefits through the fabrication of advanced sorbent beds using a 6-degree-of-freedom additive manufacturing (AM) system utilizing our patent-pending continuous-wire embedding mechanism and approach that allows us to embed thin (34-40 AWG), high-resistivity heating wires directly into the printed roads. This eliminates the need for external heaters as we can electrify the wires that are embedded throughout the sorbent structure, optimizing the heating and greatly decreasing TSA cycle time, enabling smaller beds and optimized geometries.

This technology is extremely relevant for areas that are size or weight constrained, such as space or rebreather applications. Mainstream, in conjunction with NASA, has been developing 3D printed silica gel-based and zeolite 13X columns for water vapor and CO2 removal for environmental control and life support systems in space environments such as the International Space Station (ISS). The ISS CO2 removal beds are currently pelletized zeolite-bead based processes with embedded heaters. Mainstream has developed, printed, and demonstrated a 3D monolith that enables reduction in TSA cycle time of greater than two times and reduced system size and weight. Multiple geometries and residences have been evaluated on our automated and accelerated life testing system and the performance as a function of flow channel design, geometry, and embedded wire investigated to determine the optimal engineered adsorbent structure and activity, mass transfer within the solid phase, heat conduction between feature layers, flow tortuosity (mixing versus pressure drop) and location of our embedded wires for thermal management.