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Title: CO2 induced phase transitions in diamine-appended metal–organic frameworks

Using a combination of density functional theory and lattice models, we study the effect of CO2 adsorption in an amine functionalized metal–organic framework. These materials exhibit a step in the adsorption isotherm indicative of a phase change. The pressure at which this step occurs is not only temperature dependent but is also metal center dependent. Likewise, the heats of adsorption vary depending on the metal center. Herein we demonstrate via quantum chemical calculations that the amines should not be considered firmly anchored to the framework and we explore the mechanism for CO2 adsorption. An ammonium carbamate species is formed via the insertion of CO2 into the M–Namine bonds. Furthermore, we translate the quantum chemical results into isotherms using a coarse grained Monte Carlo simulation technique and show that this adsorption mechanism can explain the characteristic step observed in the experimental isotherm while a previously proposed mechanism cannot. Furthermore, metal analogues have been explored and the CO2 binding energies show a strong metal dependence corresponding to the M–Namine bond strength. We show that this difference can be exploited to tune the pressure at which the step in the isotherm occurs. Additionally, the mmen–Ni2(dobpdc) framework shows Langmuir like behavior, and our simulationsmore » show how this can be explained by competitive adsorption between the new model and a previously proposed model.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [2] ;  [4] ;  [2] ;  [5]
  1. Univ. of California, Berkeley, CA (United States)
  2. Univ. of Minnesota, Minneapolis, MN (United States)
  3. Univ. of California, Berkeley, CA (United States); Univ. of Science and Technology, Trondheim (Norway)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, CA (United States)
  5. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
1214443
Grant/Contract Number:
AC02-05CH11231; FG02-12ER16362; SC0001015
Type:
Accepted Manuscript
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 6; Journal Issue: 9; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English