Development of 3D-Printed Polymer-MOF Monoliths for CO₂ Adsorption

Abstract

Previously, we 3D-printed polymer-zeolite monoliths by layer-wise phase separation. Importantly, this technique used liquid printing dopes, which exhibit a better rheology than traditional bentonite inks. In this work, we expanded polymer printing to metal-organic frameworks (MOFs) to address their rheological limitations. Initially, MOF-74 and HKUST-1 monoliths, with a composition of 40 wt % MOF and 60 wt % polyamide(imide) (Torlon), were printed. However, only HKUST-1 exhibited full crystalline retention. In contrast, the polymer solvents partially decomposed MOF-74, and the retained crystals were used as growth seeds. This approach produced dense MOF film monoliths with 40 wt % loading. The analysis of CO2 adsorption capacities revealed CO2 uptakes proportional to MOF loading for HKUST-1@Torlon monoliths. Moreover, secondary growth led to a 5-fold increase in CO2 capacity for MOF-74@Torlon. Namely, the isothermal adsorption capacities for the directly printed and secondary growth MOF-74 monoliths were 0.5 and 2.5 mmol/g, respectively, at 25 °C and 1 bar CO2. The dynamic performance of the composite monoliths was analyzed by fractional uptake measurements, and the results indicated that increasing the HKUST-1 loading from 40 to 60 wt % increased the diffusional resistances through the polymer-MOF monolith, whereas, for MOF-74 monoliths, the thin film, produced by secondary growth, produced the steepest fractional uptake. This monolith also exhibited a 4-fold increase in capacity compared to the directly printed MOF-74@polymer monolith (0.3 vs 1.3 mmol/g, respectively). The findings of this study highlight that direct printing of precursor seeds followed by secondary growth is a suitable approach for formulating polymer-MOF monoliths, as it balances adsorption capacity with relatively fast kinetics. Overall, this work demonstrates a 2-fold approach of formulating polymer-MOF monoliths and provides a pathway of overcoming the solvent expulsion and particle agglomeration associated with bentonite-MOF printing pastes. Moreover, this work establishes a novel route of possible scale-up of 3D-printed MOF monoliths for CO2 adsorption processes.

Department(s)

Chemical and Biochemical Engineering

Research Center/Lab(s)

Center for Research in Energy and Environment (CREE)

Keywords and Phrases

Adsorption; Bentonite; Carbon Dioxide; Growth Kinetics; Organometallics; Phase Separation; Polymers; Zeolites, Adsorption Capacities; Composite Monolith; Diffusional Resistance; Dynamic Performance; Isothermal Adsorption; Metalorganic Frameworks (MOFs); Particle Agglomerations; Polymer Monoliths, 3D Printers

International Standard Serial Number (ISSN)

0888-5885

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2019 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Nov 2019

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