(90f) ZIF-8 Membrane Performance Modification Via Facile Vapor-Phase Metal-Organic Treatment

Zeolitic imidazole frameworks (ZIFs), constructed from tetrahedral single transition metal nodes linked by imidazole-based linkers, have great potential in membrane separation due to their uniform and fine-tunable pore size and structural diversity.^[1] Since the first promising H₂ purification by solvothermally grown ZIF-8 membranes,^[2] a wide range of reports regarding ZIF membranes have emerged, demonstrating enhancements in propylene/propane separation properties by structural and chemical features of porous supports as well as membrane synthesis methods.^[3–5] Furthermore, precise tuning of gas permeation properties of ZIF-8 membranes for smaller gas molecule separations has been facilitated by postsynthetic treatments including rapid heat treatment^[6] and vapor phase ligand treatment.^[7]

This presentation will describe remarkable enhancements in both propylene/propane and H₂/CH₄ selectivity of ZIF-8 membranes by a new facile vapor phase treatment with manganese(II) acetylacetonate (Mn(acac)₂) at different temperatures (i.e., 165 °C and 175 °C, respectively).^[8] Systematic characterizations of the microstructure and compositional analysis of ZIF-8 membrane surface upon Mn(acac)₂ ­treatment (Mn-ZIF-8) will be discussed. Of particular interest is the observed ideal selectivity of 242 for H₂/CH₄ with 1.210^-7 mol m^-2 Pa^-1 s^-1 H₂ permeance at room temperature, which is facilitated by the presence of a few nanometer-thick Mn(acac)₂ deposit on the membrane surface.

Vapor-phase metal-organic treatment, employed in this work, is a facile and effective approach to tuning the gas separation properties of as-formed membranes and has great potential to be applicable with ease to other porous membranes which could display anomalous membrane performance modifications for other gas pair separations.

References

[1] Introd. to Reticular Chem. 2019, 463–479.

[2] H. Bux, F. Liang, Y. Li, J. Cravillon, M. Wiebcke, J. Caro, J. Am. Chem. Soc. 2009, 131, 16000–16001.

[3] S. Zhou, Y. Wei, L. Li, Y. Duan, Q. Hou, L. Zhang, L. X. Ding, J. Xue, H. Wang, J. Caro, Sci. Adv. 2018, 4, 1–9.

[4] X. Ma, P. Kumar, N. Mittal, A. Khlyustova, P. Daoutidis, K. A. Mkhoyan, M. Tsapatsis, Science (80-. ). 2018, 361, 1008 LP – 1011.

[5] M. N. Shah, M. A. Gonzalez, M. C. McCarthy, H. K. Jeong, Langmuir 2013, 29, 7896–7902.

[6] D. J. Babu, G. He, J. Hao, M. T. Vahdat, P. A. Schouwink, M. Mensi, K. V. Agrawal, Adv. Mater. 2019, 31, 6–11.

[7] K. Eum, M. Hayashi, M. D. De Mello, F. Xue, H. T. Kwon, M. Tsapatsis, Angew. Chemie - Int. Ed. 2019, 58, 16390–16394.

[8] M. Hayashi, D. T. Lee, M. Dorneles de Mello, A. Boscoboinik, M. Tsapatsis, Angew. Chemie Int. Ed. 2021, n/a, DOI https://doi.org/10.1002/anie.202100173.