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@ARTICLE{Chathoth:9359,
author = {Chathoth, S. and Mamontov, E. and Melnichenko, Y. and
Zamponi, M.},
title = {{D}iffusion and adsorption of methane confined in
nano-porous carbon aerogel: {A} combined quasi-elastic and
small-angle neutron scattering study},
journal = {Microporous and mesoporous materials},
volume = {132},
issn = {1387-1811},
address = {Amsterdam [u.a.]},
publisher = {Elsevier},
reportid = {PreJuSER-9359},
year = {2010},
note = {The authors wish to thank G.D. Wignall for careful reading
the manuscript and helpful suggestions. This Research at Oak
Ridge National Laboratory's Spallation Neutron Source and
High Flux Isotope Reactor was sponsored by the Laboratory
Directed Research and Development Program and the Scientific
User Facilities Division, Office of Basic Energy Sciences,
US Department of Energy. This research was supported in part
by the ORNL Postdoctoral Research Associates Program,
administered jointly by the ORNL and the Oak Ridge Institute
for Science and Education.},
abstract = {The diffusion of methane confined in nano-porous carbon
aerogel with the average pore size 48 angstrom and porosity
similar to $60\%$ was investigated as a function of pressure
at T = 298 K using quasi-elastic neutron scattering (QENS).
The diffusivity of methane shows a clear effect of
confinement: it is about two orders of magnitude lower than
in bulk at the same thermodynamic conditions and is close to
the diffusivity of liquid methane at 100 K (i.e. similar to
90 K below the liquid-gas critical temperature T-c
approximate to 191 K). The diffusion coefficient (D) of
methane initially increases with pressure by a factor of
similar to 2.5 from 3.47 +/- 0.41 x 10(-10) m(2) s(-1) at
0.482 MPa to D = 8.55 +/- 0.33 x 10(-10) m(2) s(-1) at 2.75
MPa and starts to decrease at higher pressures. An
explanation of the observed non-monotonic behavior of the
diffusivity in the confined fluid is based on the results of
small-angle neutron scattering experiments of the phase
behavior of methane in a similar carbon aerogel sample. The
initial increase of the diffusion coefficient with pressure
is explained as due to progressive filling of bigger pores
in which molecular mobility in the internal pore volume is
less affected by the sluggish liquid-like molecular mobility
in the adsorbed phase. Subsequent decrease of D, is
associated with the effect of intermolecular collisions,
which result in a lower total molecular mobility with
pressure, as in the bulk state. The results are compared
with the available QENS data on the methane diffusivity in
zeolites, metal organic frameworks, and porous silica as
well as with the molecular dynamics simulations of methane
in nano-porous carbons and silica zeolites. (C) 2010
Elsevier Inc. All rights reserved.},
keywords = {J (WoSType)},
cin = {IFF-5 / IFF-4 / Jülich Centre for Neutron Science JCNS
(JCNS) ; JCNS},
ddc = {530},
cid = {I:(DE-Juel1)VDB785 / I:(DE-Juel1)VDB784 /
I:(DE-Juel1)JCNS-20121112},
pnm = {BioSoft: Makromolekulare Systeme und biologische
Informationsverarbeitung / Großgeräte für die Forschung
mit Photonen, Neutronen und Ionen (PNI)},
pid = {G:(DE-Juel1)FUEK505 / G:(DE-Juel1)FUEK415},
shelfmark = {Chemistry, Applied / Chemistry, Physical / Nanoscience $\&$
Nanotechnology / Materials Science, Multidisciplinary},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000277551300019},
doi = {10.1016/j.micromeso.2010.02.012},
url = {https://juser.fz-juelich.de/record/9359},
}