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Title: A computational study of CH 4 storage in porous framework materials with metalated linkers: connecting the atomistic character of CH 4 binding sites to usable capacity

In order to store natural gas (NG) inexpensively at adequate densities for use as a fuel in the transportation sector, new porous materials are being developed. Our work uses computational methods to explore strategies for improving the usable methane storage capacity of adsorbents, including metal-organic frameworks (MOFs), that feature open-metal sites incorporated into their structure by postsynthetic modification. The adsorption of CH 4 on several open-metal sites is studied by calculating geometries and adsorption energies and analyzing the relevant interaction factors. Approximate site-specific adsorption isotherms are obtained, and the open-metal site contribution to the overall CH 4 usable capacity is evaluated. It is found that sufficient ionic character is required, as exemplified by the strong CH 4 affinities of 2,2'-bipyridine-CaCl 2 and Mg, Ca-catecholate. In addition, it is found that the capacity of a single metal site depends not only on its affinity but also on its geometry, where trigonal or "bent" low-coordinate exposed sites can accommodate three or four methane molecules, as exemplified by Ca-decorated nitrilotriacetic acid. The effect of residual solvent molecules at the open-metal site is also explored, with some positive conclusions. Not only can residual solvent stabilize the open-metal site, surprisingly, solvent molecules do not necessarilymore » reduce CH 4 affinity, but can contribute to increased usable capacity by modifying adsorption interactions.« less
Authors:
ORCiD logo [1] ;  [2] ;  [2] ;  [3] ;  [4]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division ; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry
  2. Univ. of California, Berkeley, CA (United States). Dept. of Chemistry
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division ; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry and Dept. of Chemical and Biomolecular Engineering
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry
Publication Date:
Grant/Contract Number:
AC02-05CH11231; CHE-1363342
Type:
Accepted Manuscript
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 7; Journal Issue: 7; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1378740