(631h) 3D-Printed Zeolite X Based Gyroid Scaffolds for CO2 Capture

Abstract: In this work, a triply periodic minimum surface (TPMS) based gyroid sheet geometry with a high surface area to volume ratio was 3D printed in the shape of a cylindrical monolith using castable wax polymer and coated with zeolite X crystals (1-S3DPP and 2-S3DPP). To improve volumetric CO₂ capture performance, zeolite X was also printed directly using photosensitive polymer resin and calcined to remove the polymer, leaving behind zeolite X monoliths with no binder (3DPZX). The 3D printing technique employed was stereolithography (SLA) because of its ability to print complex geometries such as the gyroid one. As compared to powder, a decrement of 13% and 9% in CO₂ adsorption capacity (normalized to the amount of zeolite X loading) was observed in 1-S3DPP and 2-S3DPP samples, respectively, as a result of the lower surface area and porosity of the printed samples. However, 3DPZX showed only a 4% capacity loss. CO₂ adsorption kinetics showed that printed adsorbents demonstrated faster kinetics than zeolite X powder due to their structured continuous features of gyroid geometry and high density of smooth and continuous flow channels allowing for faster gas transport and low diffusional resistance. The time taken to reach a CO₂ adsorption capacity of 4 mmol/g was 62, 57, and 66 minutes for 1-S3DPP, 2-S3DPP, and 3DPZX samples, respectively, which was significantly lower than zeolite X powder which required 110 minutes to adsorb the same amount. This study showed a facile approach to printing monoliths with complex TPMS gyroid geometry for CO₂ capture. Breakthrough performance measurement and adsorption in presence of water vapor will be further analyzed to evaluate the feasibility for industrial use^1,2.

Figure a) Silanization and coating steps b) SEM images of 2-S3DPP c) CO₂ adsorption isotherms at 25°C and 1 bar d) CO₂ adsorption kinetics at 25°C and 1 bar e) Isosteric heat of adsorption

Acknowledgement

The authors acknowledge financial support by the Center for Catalysis and Separations (CeCaS, RC2-2018-024) of Khalifa University. GNK also acknowledges support from the Research Award grant (#8474000435) from Khalifa University.

References:

1. Varghese AM, Reddy KSK, Bhoria N, Singh S, Pokhrel J, Karanikolos GN. Enhancing effect of UV activation of graphene oxide on carbon capture performance of metal-organic framework/graphene oxide hybrid adsorbents. Chem Eng J. 2021;420:129677. doi:10.1016/J.CEJ.2021.129677
2. Rangaraj VM, Reddy KSK, Karanikolos GN. Ionothermal synthesis of phosphonitrilic-core covalent triazine frameworks for carbon dioxide capture. Chem Eng J. 2022;429:132160. doi:10.1016/J.CEJ.2021.132160