a dominantly intermediate wavelength, necessarily smaller than the scale of continents. Martian
drainage patterns reflect ancient long-wavelength
topography that predates both valley network
formation and Noachian-Hesperian bombardment
(2), confirming that Noachian Mars lacked global plate tectonics and bounding post-Noachian
changes in martian relief. Our results favor dominantly long-wavelength relief-generating mechanisms on Titan such as shell-thickness variations
arising from tidal heating (6, 7) or thermal expansion and contraction (6). Together, the three
river-worn bodies in our solar system provide a
Rosetta stone for deciphering the imprint of tectonics on landscapes.
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We thank E. Chan for spot-checking martian drainages. Three
reviewers provided constructive feedback. B.A.B. acknowledges
NASA grant NNX16AR87G. D.H. thanks the Miller Institute for
Basic Research in Science. We thank the Cassini team. The
topography and drainage data used in this paper are available at
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TitanFluvialMapping_July2013 and in database S2 for Titan, and
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Materials and Methods
Figs. S1 to S8
Tables S1 and S2
Databases S1 and S2
1 June 2016; accepted 6 April 2017
Hydrolytically stable fluorinated
metal-organic frameworks for
Amandine Cadiau,1 Youssef Belmabkhout,1 Karim Adil,1 Prashant M. Bhatt,1
Renjith S. Pillai,1 Aleksander Shkurenko,1 Charlotte Martineau-Corcos,2,3
Guillaume Maurin,4 Mohamed Eddaoudi1†
Natural gas must be dehydrated before it can be transported and used, but conventional drying
agents such as activated alumina or inorganic molecular sieves require an energy-intensive
desiccant-regeneration step. We report a hydrolytically stable fluorinated metal-organic
framework, AlFFIVE-1-Ni (KAUST-8), with a periodic array of open metal coordination sites
and fluorine moieties within the contracted square-shaped one-dimensional channel. This
material selectively removed water vapor from gas streams containing CO2, N2, CH4, and higher
hydrocarbons typical of natural gas, as well as selectively removed both H2O and CO2 in
N2-containing streams. The complete desorption of the adsorbed water molecules contained
by the AlFFIVE-1-Ni sorbent requires relatively moderate temperature (~105°C) and about
half the energy input for commonly used desiccants.
Hydrolytically stable adsorbent materials that can efficiently remove traces amounts of H2O from natural gas (NG) are critical for NG transport via pipeline systems, where H2O can be corrosive or create catastrophic
blockages through methane ice formation. Cur-
rently, NG is dried with absorbents such as glycol
derivatives (1, 2) or adsorbents (solid drying agents)
(3). Solid desiccants such as zeolites 3A, 4A, and
13X achieve lower H2O(g) concentrations com-
pared with liquid absorbents, but an energy-
intensive activation step (heating to ~200°C)
is needed to achieve sufficient working capac-
ity. However, this requirement lengthens each
adsorption-desorption cycle and instigates carbon
buildup (coke formation) within the adsorbent
pore system. Commercial solid desiccants show
highly competitive adsorption of H2O and CO2;
thus, an excess of one species can greatly lower
the uptake of the other. In NG purification, CO2
often must be captured as well, and in CO2 ca-
pture from flue gas for sequestration, H2O is also
A more efficient dehydration process should
have high H2O selectivity in the presence of
other components, appreciable water uptake capacity at low H2O partial pressures, and a water
desorption cycle operating at <150°C. Microporous metal-organic frameworks (MOFs) (4–8)
have been reported that have the requisite hydrolytic stability for H2O-related applications
(9, 10). The hydrolytic stability of MOFs has
been intensively investigated, either under H2O
vapor or in liquid media (9–16), and some applications such as heat transfer (heat pumps and
chillers) have been successfully demonstrated
(16–18). However, the use of MOFs as desiccants at very low H2O concentrations remains
to be explored. We targeted the deliberate introduction of coordinately unsaturated metal
sites, using reticular chemistry and appropriate inorganic molecular building blocks, in fluorinated porous MOF materials that have periodic
arrays of fluorine moieties in contracted one-dimensional (1D) channels that have gas separation properties useful for various industrially
1King Abdullah University of Science and Technology
(KAUST), Division of Physical Science and Engineering (PSE),
Advanced Membrane and Porous Materials (AMPM),
Functional Materials Design, Discovery and Development
(FMD3), Thuwal 23955-6900, Kingdom of Saudi Arabia.
2Institut Lavoisier de Versailles (ILV), UMR CNRS 8180,
Université de Versailles St–Quentin en Yvelines (UVSQ), 45
Avenue des Etats-Unis, 78035 Versailles Cedex, France.
3CEMHTI-CNRS, UPR 3079, 1D Avenue de la Recherche
Scientifique, 45071 Orléans Cedex 2, France. 4Institut Charles
Gerhardt Montpellier (UMR CNRS 5253), Université
Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex
*These authors contributed equally to this work. †Corresponding
author. Email: firstname.lastname@example.org