Understanding volumetric and gravimetric hydrogen adsorption trade-off in metal-organic frameworks

Diego A. Gómez-Gualdrón, Timothy C. Wang, Paula García-Holley, Ruth M. Sawelewa, Edwin Argueta, Randall Q. Snurr, Joseph T Hupp, Taner Yildirim, Omar K. Farha

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Metal-organic frameworks (MOFs) are porous crystalline materials that are promising for adsorption-based, on-board storage of hydrogen in fuel-cell vehicles. Volumetric and gravimetric hydrogen capacities are the key factors that determine the size and weight of the MOF-filled tank required to store a certain amount of hydrogen for reasonable driving range. Therefore, they must be optimized so the tank is neither too large nor too heavy. Because the goals of maximizing MOF volumetric and gravimetric hydrogen adsorption loadings individually are incompatible, an in-depth understanding of the trade-off between MOF volumetric and gravimetric loadings is necessary to achieve the best compromise between these properties. Here we study, both experimentally and computationally, the trade-off between volumetric and gravimetric cryo-adsorbed hydrogen deliverable capacity by taking an isoreticular series of highly stable zirconium MOFs, NU-1101, NU-1102, and NU-1103 as a case study. These MOFs were studied under recently proposed operating conditions: 77 K/100 bar →160 K/5 bar. We found the difference between highest and lowest measured deliverable capacity in the MOF series to be ca. 40% gravimetrically, but only ca. 10% volumetrically. From our molecular simulation results, we found hydrogen "monolayer" adsorption to be proportional to the surface area, whereas hydrogen "pore filling" adsorption is proportional to the pore volume. Thus, we found that the higher variability in gravimetric deliverable capacity in contrast to the volumetric capacity, occurs due to the proportional relation between gravimetric surface area and pore volume in the NU-110x series in contrast to the inverse relation between volumetric surface area and void fraction. Additionally, we find better correlations with geometric surface areas than with BET areas. NU-1101 presents the highest measured volumetric performance with 46.6 g/L (9.1 wt %), whereas NU-1103 presents the highest gravimetric one with 12.6 wt % (43.2 g/L).

Original languageEnglish
Pages (from-to)33419-33428
Number of pages10
JournalACS Applied Materials and Interfaces
Volume9
Issue number39
DOIs
Publication statusPublished - Jan 1 2017

Keywords

  • Cryoadsorption
  • Energy storage
  • Molecular modeling
  • Nnoporous materials
  • Zirconium MOFs

ASJC Scopus subject areas

  • Materials Science(all)

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    Gómez-Gualdrón, D. A., Wang, T. C., García-Holley, P., Sawelewa, R. M., Argueta, E., Snurr, R. Q., Hupp, J. T., Yildirim, T., & Farha, O. K. (2017). Understanding volumetric and gravimetric hydrogen adsorption trade-off in metal-organic frameworks. ACS Applied Materials and Interfaces, 9(39), 33419-33428. https://doi.org/10.1021/acsami.7b01190