%0 Journal Article
%A Errahali, M.
%A Gatti, G.
%A Tei, L.
%A Canti, L.
%A Fraccarollo, A.
%A Cossi, M.
%A Marchese, L.
%D 2014
%T Understanding
Methane Adsorption in Porous Aromatic Frameworks: An FTIR, Raman,
and Theoretical Combined Study
%U https://acs.figshare.com/articles/journal_contribution/Understanding_Methane_Adsorption_in_Porous_Aromatic_Frameworks_An_FTIR_Raman_and_Theoretical_Combined_Study/2292499
%R 10.1021/jp412572e.s001
%2 https://ndownloader.figshare.com/files/3929242
%K Grand Canonical Monte Carlo
%K PAF
%K FTIR adsorption study
%K GCMC
%K CH 4 adsorption isotherms
%K CH 4 molecules
%K interaction
%K MP
%K CH 4 loading
%K methane adsorption
%K Porous Aromatic Frameworks
%K TBPM
%X We
present a vibrational study of PAF-302, belonging to the class of
porous aromatic frameworks (PAFs), recently synthesized and applied
in several applications involving gas adsorption. The precursor, tetrakis(4-bromophenyl)
methane (TBPM), and the polymer were studied with FTIR and Raman spectroscopies
to investigate the structure of PAF-302, whereas the system after
methane adsorption was studied by FTIR, also varying the CH4 loading, to get some hints on the strength of the interactions with
adsorbed methane. Theoretical calculations of the harmonic frequencies
of TBPM, methane, and methane/aromatic model systems were performed
at high theory level (MP2 with extended basis set) to support the
assignment of vibrational bands and to estimate the interactions causing
the observed frequency shifts upon methane adsorption. The analysis
shows that the polymerization process is essentially complete and
that the adsorbed CH4 molecules interact with two phenyl
rings, though stronger interactions can be envisaged. The computed
interaction energies are compatible with the isosteric heats of adsorption
previously measured for methane in PAF-302. A Grand Canonical Monte
Carlo (GCMC) approach was used to simulate CH4 adsorption
isotherms at different temperatures (87–115 K) and in the 0–0.020
bar pressure range, thus allowing us to estimate the loading of methane
in the FTIR adsorption study.
%I ACS Publications