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As featured in:
Featuring research from the group of Professor
Hong-Cai Zhou at Department of Chemistry, Texas
A&M University, College Station, Texas, USA.
Methane storage in advanced porous materials
Methane continues to gain attention as a fuel for vehicular
applications, but current storage technologies remain a barrier to
its large-scale adoption. Advanced porous materials with pore sizes
and functionalities tuned to enhance methane uptake serve to
significantly increase the density of methane through adsorption.
See Zhou et al.,
Chem. Soc. Rev., 2012, 41, 7761.
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Methane storage in advanced porous materials
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Trevor A. Makal,a Jian-Rong Li,b Weigang Lua and Hong-Cai Zhou*a
Received 10th July 2012
DOI: 10.1039/c2cs35251f
The need for alternative fuels is greater now than ever before. With considerable sources available
and low pollution factor, methane is a natural choice as petroleum replacement in cars and other
mobile applications. However, efficient storage methods are still lacking to implement the
application of methane in the automotive industry. Advanced porous materials, metal–organic
frameworks and porous organic polymers, have received considerable attention in sorptive storage
applications owing to their exceptionally high surface areas and chemically-tunable structures. In
this critical review we provide an overview of the current status of the application of these two
types of advanced porous materials in the storage of methane. Examples of materials exhibiting
high methane storage capacities are analyzed and methods for increasing the applicability of these
advanced porous materials in methane storage technologies described.
1
Introduction
The continued growth in worldwide consumption of gasoline
and diesel has led to increasing concerns over the sustainability
of oil reserves. Furthermore, the rising levels of atmospheric
carbon dioxide (CO2) produced from burning of fossil fuels have
raised awareness to the overall impact on global ecosystems.1 A
number of potential solutions for conservation and remediation
of the environment due to the impacts of CO2 release are current
on-going research topics. These include work in the capture and
storage of CO2,2–5 as well as the utilization of cleaner fuels,
a
Department of Chemistry, Texas A&M University, College Station,
TX 77842-3012, USA. E-mail: zhou@chem.tamu.edu;
Fax: +1 979 845 1595; Tel: +1 979 845 4034
b
College of Environmental and Energy Engineering, Beijing University
of Technology, Beijing, 100124, P. R. China
Trevor A. Makal obtained his
BSc in Chemistry from Texas
A&M University in 2008. He
then joined the laboratory of
Prof. Hong-Cai Zhou at
Texas A&M the same year,
where he studies the design
and synthesis of metal–organic
frameworks with a focus on
structure–property relationships as related to gas sorption
phenomena.
Trevor A. Makal
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such as natural gas (NG) or hydrogen (H2). While natural gas
does still produce CO2, it is much cleaner burning than
petroleum-based fuels. The preeminent factor preventing the
commercialization of these fuels in the automobile industry is
the discovery of effective methods to separate, capture, and
reversibly store these energy related gases. Hydrogen is one
of the most attractive fuel options because of its natural
abundance, high energy density, and non-polluting nature,
water being the only chemical by-product. A great amount of
attention has already been devoted to the development of new
materials and methods for storing hydrogen, and is outside the
scope of this review.6–12
In 2007 it was reported that 28% of greenhouse gas emissions
were generated from transportation sources, which have been
the fastest-growing source of U.S. greenhouse gas emissions.13
Natural gas vehicles (NGVs) have the potential to substantially
Jian-Rong ‘‘Jeff’’ Li obtained
his PhD in 2005 from Nankai
University under the supervision of Prof. Xian-He Bu. In
2008, he joined Prof. HongCai Zhou’s group as a postdoctoral research associate,
first at Miami University and
later at Texas A&M University; from 2010 he has been an
assistant research scientist
at the same university. Since
2011, he has been a full professor at Beijing University
of Technology. His recent
Jian-Rong Li
research interest focuses on
new porous materials for energy and environmental science.
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lower polluting emissions compared to current gasoline- and
diesel-fuelled vehicles. This is especially important for air quality
concerns in urban areas where ozone levels are particularly high
and pollutants pose a major public health concern. In addition to
reducing the emissions of nitrogen and sulfur oxides, known to
cause ‘‘acid rain,’’ it is generally agreed that NGVs have a
lower potential for causing global climate change than liquid
hydrocarbon-fuelled vehicles.14
Natural gas is composed primarily of methane (>95%),
with the remaining fraction a mixture of ethane and heavier
hydrocarbons, nitrogen, and carbon dioxide.15 Methane must
be pressurized and cooled in order to convert it to a liquid,
owing to a critical temperature of 191 K (82 1C). Methane has
a gravimetric heat of combustion (55.7 MJ kg1) comparable to
that of gasoline (46.4 MJ kg1), boasts the smallest amount of
CO2 per unit of heat produced among fossil fuels, and is
naturally abundant; but the lack of efficient storage methods
has prevented the widespread use of NG in motor vehicles.
The two common methods of NG storage currently used are
(1) liquefaction at low temperature and (2) compression to
200–300 bar at room temperature. The volumetric energy
density (VED) of liquefied natural gas (LNG; 22.2 MJ L1,
161.5 1C) achieves 64% that of gasoline (34.2 MJ L1) but
requires storage in expensive cryogenic vessels and suffers
from boil-off losses; whereas compressed natural gas (CNG)
necessitates the use of heavy, thick-walled cylindrical storage
tanks and multi-stage compressors to achieve a reasonable
VED (9.2 MJ L1), yet achieves only 27% of the VED of
gasoline. Despite efforts to improve cylinders and compressors,
the amount of NG stored in a CNG tank allows for only a short
driving range on light-duty passenger vehicles, and high
pressure storage on vehicles has associated safety concerns.
In order to realize the benefits that NG use in vehicles offers,
attractive alternatives to CNG and LNG are needed. It has
been suggested that porous adsorbents represent a safer,
simpler, and potentially more cost-effective method for storing
NG at ambient temperature and reasonable pressures (around
35 bar) in the form of adsorbed NG (ANG).16–20
In adsorption technologies a guest species adheres to the
surface of materials, forming a layer of adsorbed molecules.
Since the adsorbate is not fully surrounded by an adsorbent,
the adsorbed species may attract more adsorbate to form
multiple layers. In the case of porous materials, most sorbents
interact with guest species through weak van der Waals forces,
referred to as physical adsorption or physisorption. Alternatively,
chemical adsorption, chemisorption, occurs in the case of significant covalent interaction between adsorbents and adsorbates (e.g.
chemical hydride formation in hydrogen spillover processes).
From an application standpoint, the primary difference between
physisorption and chemisorption is the significant disparity in
binding energies. For reversible gas storage and delivery, moderate
binding energies (heats of adsorption) are required to maximize
energy efficiency of the system. Therefore, physisorptive materials
are best suited for this application, as chemisorptive materials
would require a substantial amount of external heat to deliver
the adsorbed gas.
The potential for at-home refuelling from domestic pipelines, using formable lightweight fuel tanks, and reduced safety
concerns relative to that of LNG and CNG are major benefits
to the use of ANG technologies for on-board vehicular fuel
storage.15,17,21 Identifying this potential, the United States
Department of Energy (DOE) has issued a call for the development of sorbents capable of achieving volumetric and gravimetric
capacities >12.5 MJ L1 (314.2 vCH4 (STP)/vsorbent) and
>0.5 gCH4/gsorbent (700 cm3CH4 (STP)/gsorbent), respectively,
at reasonable pressure and temperature ranges (40 1C to
85 1C and r35 bar) in order to achieve targets of >9.2 MJ L1
and >0.4 gCH4/gsorbent in an ANG fuel storage system for
passenger vehicle usage. The ideal sorbent should also show
resistance to impurities typically encountered in natural gas
sources with a lifetime of at least 100 fill–release cycles, and
approach $10/kgsorbent, in addition to other system level targets
(desorption rates, tank abuse tests, etc.).
Recent advancements in NG-adsorbing, high surface area
materials have shown promise for increasing the density of
NG under moderate conditions in the form of ANG, and
Weigang Lu received his
PhD in Organic Chemistry
(2002) from Sun Yat-Sen
University under the supervision of Prof. Longmei Zeng.
He was an assistant professor
at Sun Yat-Sen University
(2002–2005), and then worked
for Biotechnology Research
Institute at Hong Kong
University of Science & Technology
(2005–2008).
In
December 2008, he joined
Prof. Hong-Cai Zhou’s group
as a postdoctoral research
Weigang Lu
associate at Texas A&M University. His research interests include the rational design and
synthesis of porous materials (metal–organic frameworks and
porous polymer networks) and their application in gas storage
and separation.
Hong-Cai ‘‘Joe’’ Zhou obtained
his PhD in 2000 from Texas
A&M University under the
supervision of F. A. Cotton.
After a postdoctoral stint at
Harvard University with R. H.
Holm, he joined the faculty of
Miami University, Oxford, in
2002. Since the fall of 2008,
he has been a professor of
chemistry at Texas A&M University. His research interest
focuses on gas storage and
separations that are relevant to
clean energy technologies.
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Hong-Cai Zhou
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provide a significant opportunity to develop small, light-weight,
and high capacity tanks for vehicular application. These materials
include activated carbons,5,6 metal–organic frameworks,7,8 and
porous organic polymers.9 ANG technology increases NG density
by condensation in the sorbent’s micropore structure at ambient
temperatures and pressures of 30 to 40 bar (5- to 8-times lower
than CNG for comparable VED).10
Historically, activated carbons and zeolites have been the
most studied microporous materials (pore diameter o 2 nm)
for the storage of gases, including methane. However, the
difficulty in tuning pore shapes and sizes in activated carbons,
as well as the limited number of structures, low surface areas,
and hydrophilicity of zeolites has limited the utility of these
materials in gas storage, including NG.
Metal–organic frameworks (MOFs) have garnered a significant amount of attention as advanced porous materials in the
past two decades.22,23 Despite the relatively short time since
MOF research began, the field has grown explosively not only
in number of structures and publications but also in the scope
of research topics this new class of porous inorganic–organic
hybrid materials has broken into. Metal containing units play
the role of nodes in the framework system as individual ions/
atoms, discrete polynuclear clusters, or infinite chains/sheets,
and are connected to one another through coordinatively
bound organic struts, Fig. 1. The connectivity of metal and
organic linkers results in crystalline materials with regular
porosity that can be structurally characterized using X-ray
diffraction methods.24 For some materials, the system is stable
enough to realize permanent porosity upon included guest
removal. Utilizing knowledge of the geometry of the building
units observed in MOFs, several examples of frameworks
exhibiting the same net topology throughout a series (termed
isoreticular MOFs) have now been synthesized using similar
geometry and number of binding sites of metal and organic
components.25–28 Using reticular synthesis (synthesis aimed
toward a particular net topology) the functionalities of MOFs
may be tuned while maintaining desired porous properties, such
as a specific pore shape or size. Systematically approaching
materials design at the molecular level,29–32 with a clear focus
on the resulting physical properties, has been one of the keys
to success in the versatile MOFs field, which has demonstrated
potential in catalysis,33–54 ion exchange,55–60 gas storage,16,61–73
separation,74–83 sensing,84–94 polymerization,95–98 and drug
delivery,99–106 in addition to fundamentally interesting properties
including optic,107–113 magnetic,114–121 and electronic nature.122–130
Along with MOFs, porous organic polymers (POPs, Fig. 1)
have been identified to exhibit exceptional porosity and tantalizing
potential as materials for gas storage and separation applications.131–135 POPs are porous materials composed predominantly of light, non-metallic elements such as carbon,
hydrogen, boron, oxygen, nitrogen, silicon, and phosphorus
that are connected through strong covalent bonds.136,137 POPs
may be divided into two sub-classes: crystalline and amorphous.
Crystalline POPs have much in common with MOFs; they are
also formed through reversible bond-forming chemistry and
have regular, ordered porosity. A representative example of
crystalline POPs is covalent organic frameworks (COFs), which
were formed either by the self-condensation of boronic acids
or by the condensation reaction of boronic acid with diols to
form boroxines and others in limited cases. COFs were first
systematically studied by Yaghi and coworkers.138,139 On the
other hand, amorphous POPs were usually formed through
irreversible condensation reactions, which typically result
in disordered structures and wide pore size distributions.
Consequently, the structures of amorphous POPs are difficult
to determine; instead, a model of a single net may be formulated
based upon the geometric combination of building units, and
the degree of interpenetration determined from pore size
distribution calculated from gas sorption analyses. Due to
the rigidity of covalent bonds, amorphous POPs show extraordinary stability and tolerance toward water and other
chemicals, which often displaces coordinated organic linkers
from metals in MOFs.140,141 Different reactions have been
used for synthesizing amorphous POPs, and they were named
separately by individual research groups, such as hypercrosslinked polymers (HCPs),142 polymers of intrinsic microporosity
(PIMs),143 conjugated microporous polymers (CMPs),144 element–
organic frameworks (EOFs),145 porous aromatic frameworks
(PAFs),133 and porous polymer networks (PPNs).136 The low
density, high porosity, and high stability of POPs have led to
increasing interest in application of these materials. Here, we
review the current state of methane storage in MOFs and POPs,
focusing on methods/strategies for increasing the methane storage
capacity of these materials.
2 Methane adsorption in traditional porous
materials
Fig. 1 Schematic showing the self-assembly processes in advanced porous
materials, metal–organic frameworks and porous organic polymers.
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Many porous materials, such as aluminosilicate zeolites, carbon
and metal-oxide molecular-sieves, aluminophosphates, activated
carbon, activated alumina, carbon nanotubes, silica gel, pillared
clays, inorganic and polymeric resins, MOFs, and porous metal–
organic composites, have been explored as adsorbents, some of
which are now used in industry. Relevant reviews and monographs have summarized the syntheses, structures, characterizations, adsorption properties, and applications of these
materials.146–152 Methane storage in porous materials has been
an active area of research for some time, with the adsorptive
Chem. Soc. Rev., 2012, 41, 7761–7779
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potential of charcoals toward methane being dated back to at
least 1930.152 During the 1990s research into ANG technologies
increased in popularity and the prospects and results of several
different types of traditional porous materials were reviewed by
Menon and Komarneni.15
Based on the considerable amount of data that have been
collected on various types of porous materials, it can be concluded
that adsorption and storage of methane in porous materials follow
similar trends to that of hydrogen. In particular, a direct correlation
between surface area with adsorption capacity is observed,
irrespective of the chemical character of the adsorbent.64
However, enhancing the VED remains difficult as an increase
in the surface area of materials generally leads to a decrease in
density of the material, and inefficient packing of bulk samples
reduces the enhancement factor achieved by using ANG.
A number of experimental and modelling studies on the
application of traditional porous materials in ANG technologies
have been reported, but only a brief overview is included herein.
2.1
Zeolites for methane storage
In the beginning stages of research into ANG storage systems,
synthesis procedures for developing high surface area carbons
were not well documented.15 Therefore, zeolites were the first
materials looked to as adsorbents for ANG technologies.153
Studies involving methane adsorption in zeolites continue
to assist in the understanding and design of adsorbent
materials;154–162 however, their application as NG sorbents is
limited. Issues that demonstrate a major constraint with the
application of zeolites in ANG storage systems are the structural limitations which prevent the realization of accessible
surface areas greater than 1000 m2 g1 and the ionic nature of
the material. As methane has no permanent dipole or quadrupole moments, the ionic nature of zeolites is not beneficial to
the adsorption of methane and leads to preferred adsorption
of other guest species. In particular, the pore surfaces of
zeolites are exceptionally hydrophilic, leading to preferred
adsorption of water in gas mixtures, significant retention of
water per charge–discharge cycle, and, therefore, diminished
overall storage capacity.
Additionally, macroporosity, an unavoidable product
during bulk packing of crystals, is not beneficial in the storage
of methane in ANG systems.163 This is due to little interaction
between the methane guest molecules and the pore surfaces of
the sorbent as the pore size increases. A large number of
macropores in the form of interparticle voids are formed due
to imperfect packing. The packing density of zeolites may
be increased, but at the expense of having very low micropore surface areas. A methane storage system utilizing adsorbents for methane-powered vehicles has been patented
by Stockmeyer.164 The data from this patent indicate that
compacting CaX zeolite to 0.8 g mL1 can improve methane
storage capacity to 150 v(STP)/v (volume of methane at
standard temperature and pressure, 273.15 K and 1 bar, per
unit volume of sorbent; denoted v/v henceforth), at ambient
temperature and about 9.1 bar.15 However, the methane
storage capacity of CaX zeolite compacted to 0.8 g mL1
leads to a capacity of 98 v/v, according to data from Zhang
and coworkers.15,162
7764
Chem. Soc. Rev., 2012, 41, 7761–7779
2.2 Carbonaceous materials for methane storage
Being one of the most studied types of porous materials,
naturally, carbonaceous materials have been investigated
for their application in methane storage.21,146,147,150,151,165–199
Activated carbons and carbon nanotubes with very narrow
pore size distributions are the primary carbonaceous materials
that have been studied for gas adsorption and storage
applications.
Through various computational and experimental studies
on activated carbons, those with slit-shaped pores were predicted to provide the greatest volumetric methane capacity,200,201 and pore widths of 0.8–1.5 nm were proposed to
be most effective for methane storage.202–205 Furthermore, a
study by Celzard and Fierro determined that, in addition to
the micropores, the meso- and macropores play a role in the
deliverable capacity of methane in carbonaceous materials.206
They determined that larger pores assist in the diffusion of
methane through the pores of the system, thereby enhancing
loading/unloading rates, and also contribute to overall uptake
capacity, based upon comparison of experimental and computational results. Upon processing the carbons, they were able to
obtain a methane storage capacity of B195 v/v at 295 K and
35 bar.
Microporosity in carbons is generally created by removal of
carbon atoms through activation, often by treatment with acid
or base; however, ‘‘over-activation’’ may lead to the generation
of macropores and a decrease in packing density.207 Because of
this ‘‘over-activation’’ the development of very high surface
area carbons often produces low density materials that exhibit
low VED. Therefore, the development of porous carbon
sorbents has shifted to enhancing the bulk density of samples,
rather than only increasing surface areas. Different compaction methods have been explored to decrease the presence of
macropores and enhance the bulk densities of materials,
including grinding,204 compression,208,209 and formation of
monoliths,21,194 among others.
Prototypes of ANG-fuelled vehicles utilizing activated carbons
have been previously demonstrated with exciting potential.210,211
The opportunity to use agricultural by-products as starting
materials for production of high surface area activated carbons
is an attractive option for reducing the cost of production of
porous materials.212,213 However, limitations in pore size
distribution, accessible surface area, pore volume, and surface
functionalization lend focus to advanced porous materials to
further increase the practicality of ANG technologies.
3 Advanced porous materials for high methane
storage
3.1 Metal–organic frameworks (MOFs)
MOFs present a unique blend of the benefits of both zeolites
and porous carbons.215 The crystalline nature and regular,
ordered porosity of the materials make absolute characterization a simple task, and permit in-depth structural and
host–guest studies to be conducted. Additionally, exceptionally
high surface areas may be obtained and the character of the
framework is easily adjusted by incorporation of functional
groups or post-synthetic modification of the system.216–222
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The first reported measurement of methane uptake by
a porous MOF can be dated to 1997 by Kitagawa and
co-workers.223 While volumetric storage capacity has been
emphasized, to date, the reported volumetric storage capacity
of a MOF is usually calculated from the gravimetric capacity
and the crystallographic density of the material. This leads to an
idealized maximum volumetric capacity for the framework, as it
would be impractical to grow a single crystal large enough to
accommodate enough methane for any practical use, and there
is a limit to the degree of densification that can occur before
causing structural damage or severely limiting diffusion of gas.
While the application of MOFs in methane storage has not
received nearly as much attention as that for hydrogen storage
or carbon dioxide capture, a number of researchers have
investigated methane uptake in MOFs. A compilation of
reported methane uptake in high capacity MOFs, in addition
to other thoroughly studied MOFs, is provided in Table 1.
Discussion of investigations on methane binding sites in
MOFs and then analysis of several examples of high capacity
MOFs follows.
3.1.1 Identifying methane adsorption sites. The Raman
spectroscopic investigation of methane adsorption in isoreticular MOFs (IRMOFs) indicates that the gas molecules
adsorb to the IRMOF linkers inside the framework cavities
under conditions of temperature and pressure that are most
relevant to a storage system. These results point to the critical
role that the linkers play in the adsorption behavior of
methane in MOFs, thus revealing that selection of appropriate
linkers with the highest affinity for methane will provide an
optimal storage material.224 This conclusion is in contrast to
that found for H2 storage in MOFs.225–229 In the case of the
adsorption of H2 in MOFs the linker has been identified to
play a relatively minor role in the adsorption process. Instead,
coordinatively unsaturated metal centers (UMCs) have been
routinely identified as exhibiting the highest affinity toward
dihydrogen, with heats of adsorption generally lower than
what has been observed for methane sorption in MOFs, the
highest H2 heat of adsorption reported being 13.5 kJ mol1.230
The UMC binding sites are made available upon removal of
coordinated solvent or guest molecules. This is typically
Surface area, pore volume, methane storage properties under specific conditions for metal–organic frameworks
Table 1
Surface area m2 g1
a
BET
Compound
Lang.
Condition
Methane uptake capacity
Pore volume/
DHads/kj mol1
3 1
P/bar
T/K wt%e
v(STP)/vf
(zero coverage) Ref.
cm g
0
Co2(4,4 -bipy)3(NO3)4
Cu2(pzdc)2(pyz)
Cu2(pzdc)2(4,4 0 -bipy)
Cu2(pzdc)2(pia)
CuSiF6(4,4 0 -bipy)2
Zn4O(bdc)3 [MOF-5, IRMOF-1]
Zn4O(pdc)3 [IRMOF-14]
Al(OH)(bdc) [MIL-53(Al)]
Cr(OH)(bdc) [MIL-53(Cr)]
Cr3F(H2O)3O(btc)2 [MIL-100]
Cr3FO(bdc)3 [MIL-101]
Cr3O(H2O)2F(ntc)1.5 [MIL-102(Cr)]
Al4(OH)8(btec) [MIL-120]
Cu2(sbtc) [PCN-11]
Cu2(adip) [PCN-14]
Cu2(tdm) [PCN-26]
Cu2(btei) [PCN-61]
Cu2(ntei) [PCN-66]
Cu2(ptei) [PCN-68]
Cu3(btc)2 [HKUST-1]
Zn2(bdc)2dabco
Ni2(dhtp) [NiMOF-74, CPO-27-Ni]
Mg2(dhtp) [MgMOF-74, CPO-27-Mg]
Mn2(dhtp) [MnMOF-74, CPO-27-Mn]
Co2(dhtp) [CoMOF-74, CPO-27-Co]
Zn2(dhtp) [ZnMOF-74, CPO-27-Zn]
Cu3(bhb) [UTSA-20]
Cu(1,4-ndc)
Cu2(ebtc)
Cd2(azpy)3(NO3)4
Cu2(Hbtb)2
Zn4O(btb) [MOF-177]
Zn4O(bbc)2 [MOF-200]
Zn4O(btb)4/3(ndc) [MOF-205]
Zn4O(bte)4/3(bpdc) [MOF-210]
[Fe3O(bdc)3][FeCl4] [MOF-235]
Zn(bdc)(4,4 0 -bipy)0.5 [MOF-508b]
Zn4O(bdc)(btb)4/3 [UMCM-1]
Zn8(bhfp)33 [FMOF-2]
Zn2(BPnDC)2(4,4 0 -bipy) [SNU-9]
Mg(tcpbda) [SNU-25]
Zn(mIm)2 [ZIF-8]
Zn(Pur)2 [ZIF-20]
This journal is
c
1870
1100
1100
2693
308
1931
1753
1854
3000
4000
5109
1502
1448
1027
1332
1102
1056
885
1156
168
1852
600
4833
4530
4460
6240
974
824
795 (DR)
1264
4800
1590
1500
1900
4492
42
432
2442
2545
3500
4600
6033
2368
2104
2.3
0.59
0.56
1.1
2.15
0.12
0.11
0.91
0.87
0.84
1.36
1.63
2.13
0.82
0.75
0.54
0.63
322.5
2844
5403
946
4100
378
1030
800
The Royal Society of Chemistry 2012
1.96
3.59
2.16
3.6
0.93
2.141
0.366
0.368
0.51
0.27
30.4
30.4
30.4
30.4
36.5
36
298
298
298
298
298
300
3.6c
1.3c
3.9c
4.4c
9.4d
13.5b
71c
32c
35
35
50
60
30
10
25
35
1.07
35
35
35
35
75
49.7 (35)
58.3 (35)
35
35
35
35
20
1
36
25
100
80 (35)
80 (35)
80 (35)
10
4.5
25
30
65
1.01
30
1.01
298
298
303
303
303
303
298
290
298
298
298
298
304
298
298
298
298
298
298
298
298
273
298
298
298
298
298
298
298
303
298
298
298
298
298
273
8.8d
8.8d
10.7c
17.9c
2.2c
2.8d
14.0b
15.3b
1.7d
15.7b
15.1b
15.7b
10.2c
14.3c
11.9b
13.7b
155d
165d
2.2d
2.2d
2.8c
5.3d
22.0d
19.0b
20.5b
20.9b
3.2d
11.4d
B2.2d
3.4b
0.7d
B6.5d
1.2d
124d
110b
56c
12.2
10
17
17
19
18
171b
220b
27
14.6
30
145b
10b
99b
165c
202c
195b (190)b
169b (149)b
158b
174b
171b
178b
18.7
21.5–22
17.7
60c
311d
(41)b
(93)b
(53)b
69.9d
52.6
b
6.5
223
268
268
268
269
270
17, 271
272
272
273
273, 274
275
276
277
19
79
27
27
27
274
274
214, 278
214, 278
214
214
214
238
279
280
281
282
283, 284
251
251
251
285
286, 287
288
289
290
291
292
293
Chem. Soc. Rev., 2012, 41, 7761–7779
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Table 1
(continued )
Surface area m2 g1
a
BET
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Compound
Zn(bIm)(nIm) [ZIF-68]
Zn(cbIm)(nIm) [ZIF-69]
Zn(Im)1.13(nIm)0.87 [ZIF-70]
Zn(nbIm)(nIm) [ZIF-78]
Zn(mbIm)(nIm) [ZIF-79]
Zn(bbIm)(nIm) [ZIF-81]
Zn(cnIm)(nIm) [ZIF-82]
Zn2(bttb)
Zn4O(fma)3
[H3O][Zn7(m3-OH)3(bbs)6]
Zn2(2,6-ndc)2(dpni), solution synthesis
Zn2(2,6-ndc)2(dpni), microwave synthesis
Co3(2,4-pdc)2(m3-OH)2 [CUK-1]
Zn3(OH)(p-cdc)2.5
Cu3(btc)2, extrudates
Mn(2,6-ndc)
Cu(tip)
Cu2(tmbdi) [NOTT-107]
Cu(Hoxonic)(4,4 0 -bpy)0.5
Cu(bdc-OH)
Zn5(bta)6(tda)2
Zn4(OH)2(1,2,4-btc)
Co3(ndc)(HCOO)3(m3-OH)
Zr(bdc) [UiO-66]
Cu2(bbcpm)
Lang.
Condition
Methane uptake capacity
Pore volume/
DHads/kj mol1
3 1
P/bar
T/K wt%e
v(STP)/vf
(zero coverage) Ref.
cm g
1090
950
1730
620
810
760
1300
1370
1120
1618
649
802
167
630
152
>2000
810
1822
191
1063
0.24
0.34
0.064
0.26
0.068
0.34
0.767
414
408
1386
584
607
607
1434
0.214
0.24
0.205
0.58
2010
2665
0.72
1.01 (35) 298 0.7d
1.01
298 0.9d
1.01 (35) 298 0.7d
1.01
298 1.0d
1.01
298 0.8d
1.10
298 0.8d
1.01
298 0.8d
17.5
298 5.2d
28
300 8.6d
1.01
273 0.9d
17.5
298 3.1b
17.5
298 3.9b
1.01
298 0.6d
0.5
298 0.1d
50
303 11.2d
1.01
273 1.3d
1.01
298 1.6d
35
298
25
273 0.8d
1.01
296 0.9d
1.01
295 0.7d
1.01
295 0.7d
1
298 1.1d
9.8
273 5.5d
8.03
295 6.1d
(150)d
d
(150)
12
16.6
185b
18.5
19.4
15.7
294
294
294
294
294
294
294
295
296
297
298
298
299
300, 301
302
303
304
235
305
306
307
308
309
310
311
4,4 -bipy = 4,4 -bipyridine; pzdc = pyrazine-2,3-dicarboxylate; pyz = pyrazine; pia = N-(pyridin-4-yl)isonicotinamide; bdc2 = benzene1,4-dicarboxylate; pdc2 = pyrene-2,7-dicarboxylate; btc3 = benzene-1,3,5-tricarboxylate; ntc4 = naphthalene-1,4,5,8-tetracarboxylate; btec4
= benzene-1,2,4,5-tetracarboxylate; sbtc4 = trans-stilbene-3,3 0 ,5,5 0 -tetracarboxylate; adip4 = 5,5 0 -(9,10-anthracenyl)di-isophthalate; tdm8 =
tetrakis[(3,5-dicarboxyphenyl)oxamethyl]methane; btei6 = 5,5 0 ,500 -benzene-1,3,5-triyltris(1-ethynyl-2-isophthalate); ntei6 = 5,5 0 ,500 -(4,4 0 ,400 nitrilotris(benzene-4,1-diyl)tris(ethyne-2,1-diyl))triisophthalate; ptei6 = 5,5 0 -((5 0 -(4-((3,5-dicarboxyphenyl)ethynyl)phenyl)-[1,1 0 :3 0 ,100 -terphenyl]4,400 -diyl)-bis(ethyne-2,1-diyl))diisophthalate; H2dhtp = 2,5-dihydroxyterphthalic acid; bhb6 = 3,3 0 ,300 ,5,5 0 ,500 -benzene-1,3,5-triyl-hexabenzoate;
1,4-ndc2 = naphthalene-1,4-dicarboxylate; ebtc4 = 1,1 0 -ethynebenzene-3,3 0 ,5,5 0 -tetracarboxylate; bbc3 = 4,4 0 ,4-[benzene-1,3,5-triyltris(benzene-4,1-diyl)]tribenzoate; btb3 = 4,4 0 ,4-benzene-1,3,5-triyl-tribenzoate; bpdc2 = biphenyl-4,4 0 -dicarboxylate; bhfp2 = 2,2-bis(4-carboxyphenyl)hexafluoropropane; BPnDC2 = benzophenone 4,4 0 -dicarboxylate; tcpbda2 = N,N,N 0 ,N 0 -tetrakis(4-carboxyphenyl)biphenyl-4,4 0 -diamine; mIm = 2-methylimidazolate; Pur = purinate; bIm = benzimidazolate; nIm = 2-nitroimidazolate; cbIm =
5-chlorobenzimidazolate; Im = imidazolate; nbIm = 5-nitrobenzimidazolate; mbIm = 5-methylbenzimidazolate; bbIm = 5-bromobenzimidazolate; cnIm = 4-cyanoimidazolate; bttb4 = 4,4 0 ,4,4-benzene-1,2,4,5-tetrayltetrabenzoate; 2,6-ndc2 = 2,6-naphthalenedicarboxylate;
dpni = N,N 0 -di-(4-pyridyl)-1,4,5,8-naphthalene tetracarboxydiimide; 2,4-pdc2 = pyridine-2,4-dicarboxylate; p-cdc2 = 1,12-dicarba-closododecaborane-1,12-dicarboxylate; tip2 = 5-(1H-tetrazol-1-yl)isophthalate; tmbdi4 = 5,5 0 -(2,3,5,6-tetramethylbenzene-1,4-diyl)di-isophthalate;
H3oxonic = 4,6-dihydroxy-1,3,5-triazine-2-carboxylic acid; bdc-OH2 = 2-hydroxyterephthalate; 1,2,4-btc2 = benzene-1,2,4-tricarboxylate;
bta = 1,2,3-benzenetriazolate; tda2 = thiophene-2,5-dicarboxylate; bbcpm4 = 1,1-bis-[3,5-bis(carboxy) phenoxy]methane; azpy =
4,4 0 -azopyridine. b Excess uptake. c Total (absolute) uptake. d Not reported whether excess or total (absolute) uptake. e wt% =
massCH4 adsorbed
f
masssorbent þmassCH adsorbed 100%. Reported volumetric uptake capacities assume crystallographic densities.
a
0
0
2
4
accomplished through a solvent exchange process in which
relatively high boiling point solvent is decanted from a freshly
prepared sample and replaced by a solvent with lower boiling
point, such as methanol or dichloromethane. Repeating this
process permits the complete replacement of higher boiling
point solvent coordinated to the metal center by the lower
boiling solvent which may be removed more easily, generally
under dynamic vacuum and slight heating. Alternative methods for removing these coordinated molecules include use of
supercritical carbon dioxide, freeze-drying, and simple heating
under vacuum. However, not all MOFs can withstand the
stress placed on the framework due to removal of guest species
from the pores and metal centers, particularly under elevated
temperatures, and undergo structural collapse upon guest
removal.
However, for the MMOF-74 (M2(dhtp), M = Mg, Mn, Co,
Ni, Zn, dhtp4 = 2,5-dihydroxy terephthalate) series of
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Chem. Soc. Rev., 2012, 41, 7761–7779
MOFs, also referred to as the CPO-27-M series, neutron
powder diffraction measurements led to the identification of
UMCs as the primary methane binding sites, Fig. 2.116,214,231
Extension of this type of study to MOFs with a lower density
of UMCs (HKUST-1, PCN-11, and PCN-14), and through a
combination of neutron diffraction, grand canonical MonteCarlo (GCMC) simulations, and density functional theory
(DFT) calculations, the methane sorption sites in these three
MOFs were unambiguously identified.232 In this study it was
identified that while the UMCs were the primary adsorption
sites with the highest heats of adsorption, the amount of methane
adsorbed onto these sites was not substantial. Instead, the ligand
played the primary role in overall storage capacity of methane in
the system. Furthermore, it was identified that accessible small
cages and channels that exhibit enhanced van der Waals interactions due to potential overlap are favorable methane binding
sites, Fig. 3. This study identified that surface area and ligand
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Fig. 3 Experimentally determined partial structure of the HKUST-1
crystal with CH4 molecules adsorbed at (a) the open Cu sites and (b)
the small cage window sites (top and side views). (c) van der Waals
(vdW) surface of the small octahedral cage in HKUST-1 (derived by
using N2 as probe molecules), showing the size and geometry of the
pore window in an excellent match with a methane molecule. (d) CH4
molecule adsorbed at the center of the small octahedral cage, a
secondary adsorption site. (e) CH4 molecule located at the large cage
corner site, also a weak adsorption site. Reprinted with permission
from ref. 232. Copyright 2010 John Wiley and Sons.
Fig. 2 (a) Crystal unit cell of Mg2(dhtp) with methane adsorbed on
site I (the open metal site), as determined from neutron diffraction. Note
that each metal ion directly binds to one methane molecule. (b) Experimental Mg2(dhtp) structure with methane adsorbed on both sites I and II.
(c) A close view of methane location and orientation with respect to the
metal-oxide pyramids and the organic linkers. Reprinted with permission
from ref. 214. Copyright 2009 American Chemical Society.
functionality were less important parameters to consider than
the tuning of pore shapes and sizes. This, in combination with
experimental results,19 signifies the role of larger organic components enhancing the methane capacity of porous MOFs.
Some MOFs have shown high methane storage capacities,
as exemplified in the following examples. These materials have
set the trend for methane storage in MOFs and may be looked
at for inspiration in designing high performing adsorbents.
3.1.2 MOF example 1: PCN-14. A theoretical MOF (IRMOF-993) based on 9,10-anthracene dicarboxylate and Zn4O
SBUs was predicted to increase the methane isosteric heat of
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adsorption and achieve a storage capacity of 181 v/v.17 However, attempts to experimentally reproduce the theoretical
measurements of IRMOF-993 led to a MOF (PCN-13)
exhibiting selective adsorption of hydrogen and oxygen over
nitrogen and carbon monoxide, but very limited methane
uptake due to the confined pore space (B3.5 Å).233 The
variance between gas uptake properties and pore size from
expected (6.3 6.3 Å2, IRMOF-993) and that experimentally
determined in PCN-13 was explained from observation of
distortion of the Zn4O(COO)6 metal building units in the
crystal structure. Building upon the design of IRMOF-993,
the microporous material PCN-14 was synthesized from the
self-assembly of 5,50 -(9,10-anthracenediyl)diisophthalate (adip4)
and dicopper paddlewheel SBUs.19 The combination of fourconnected square planar metal SBUs and four-connected
rectangular planar organic linkers led to the formation of a
framework with nbo net topology. This topology has been
identified in a number of other frameworks constructed from
dimetal paddlewheel and tetratopic organic carboxylate
SBUs.26,234 PCN-14 is composed of squashed cuboctahedral
cages constructed from the connection of twelve adip4
ligands to six dicopper paddlewheels, Fig. 4, bringing the
anthracenyl rings within close proximity to one another
(2.6 Å between H atoms and center of phenyl rings on the
adjacent anthracenyl group). This orientation of organic
linkers within the framework system leads to enhanced interactions between guest methane molecules and the pore surfaces.
Chem. Soc. Rev., 2012, 41, 7761–7779
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Fig. 4 (a) Squashed cuboctahedral cage; (b) nanoscopic cage with 18
vertices, 30 edges, and 20 faces. Color scheme: C, gray; Cu, turquoise;
and O, red. Reprinted with permission from ref. 19. Copyright 2008
American Chemical Society.
The removal of coordinated solvent from the terminal sites of
the dicopper paddlewheel leads to the formation of UMCs
that are appropriately oriented toward the center of the
cuboctahedral cages so as to maximize interactions with guest
species. The combination of small pore diameter and available
UMCs permits a high total uptake of methane (230 v/v) at
290 K and 35 bar. PCN-14 continues to be the record holder
for volumetric methane uptake in a solid porous material, to
the best of our knowledge.
Since publication of PCN-14, computational studies have
analyzed the methane uptake capacity of PCN-14 with a very
recent report, based on GCMC simulations, predicting a lower
storage capacity of 205 v/v under the same conditions as the
experimental measurement.235 Since the field of MOF research
is still very young, computational models must rely on fitting
to empirical data to evaluate the efficacy of a model. It has
been suggested that one force field may not be applicable
across the entire range of framework materials; as such,
another recent report proposed a new force field for simulating
the adsorption of methane in PCN-14 that better fits the
experimental data, as well as describes the adsorption behavior
and observed adsorption site specificity in PCN-14.236 Based
on the study conducted utilizing this new force field, it was
found that no energy barrier is observed between strong and
weak adsorption sites in PCN-14. Instead, at room temperature, a cooperative binding effect is observed in which UMCs
attract incoming methane guests and direct them to nearby
binding sites, such as locations with small pore diameter that
maximize potential overlap between the pore surfaces and
guest species, Fig. 5. Alternatively, at lower temperature,
150 K, the UMCs act as the primary binding site, matching well
with experimental results from neutron diffraction studies.232,236
The results defining the UMCs in PCN-14 as weak methane
adsorption sites corroborated those previously reported in a
study of HKUST-1 (Cu3btc2).237 In the HKUST-1 study
methane molecules were found to be uniformly dispersed
throughout the unit cell with no specific adsorption sites. This
is in stark contrast to the adsorption behavior of carbon
monoxide in the same material, in which CO molecules were
found to adsorb near the UMCs. This difference in adsorption
sites arises from the fact that methane is an essentially
spherical molecule (tetrahedral with no dipole moment, freely
rotating at room temperature) that is very difficult to polarize,
whereas CO is a polar molecule with lone pairs that can easily
interact with UMCs.
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Chem. Soc. Rev., 2012, 41, 7761–7779
Fig. 5 Probability distributions of the centers of mass of methane in
PCN-14 at (a) 3500 kPa and 290 K and (b) 5 kPa and 150 K, viewed
along the [2 1 1] crystallographic direction. The circles show the
probability distributions of the centers of mass of methane molecules
in the region where methane molecules are expected to be positioned to
populate the open Cu site. Reprinted with permission from ref. 236.
Copyright 2011 American Chemical Society.
3.1.3 MOF example 2: NOTT-107. Through the use of a
high-throughput computational screening of potential MOFs
for efficient methane sorbents, a MOF similar to PCN-14
(NOTT-107) was identified which had been previously synthesized, but the methane uptake capacity remained unstudied
until recently.26,235 NOTT-107 is based upon 5,5 0 -(2,3,5,6-tetramethylbenzene-1,4-diyl)di-isophthalate and dicopper paddlewheel SBUs. The methyl substituents on the central phenyl
ring of NOTT-107 play a role similar to that of the phenyl rings
of the anthracenyl moiety that extend into the pores of the
framework in PCN-14. In both systems these groups effectively
reduce the pore diameter, in the case of NOTT-107, to 7.0 Å.26
The methane capacity of NOTT-107 was calculated from
GCMC simulations using the Universal Force Field.235 These
calculations determined a potential storage capacity of 213 v/v
at 298 K and 35 bar. The enhancement in methane uptake is
believed to be similar to the reasoning behind that for PCN-14,
in which the close contacts created from extension of the
ligands into pores of the framework form ‘‘pockets’’ where
methane can interact strongly with the framework. To compare
their simulated results, a sample of NOTT-107 was prepared,
activated, and tested for gas uptake properties. The experimental methane uptake was found to be lower than that of the
simulated results (B196 v/v). This was attributed to a likely
incomplete activation procedure and was corroborated when
the experimental BET surface area (1770 m2 g1) was determined to be lower than what was calculated from simulations
(2207 m2 g1). The experimental BET surface area determined from
the first account of NOTT-107 was reported to be 1822 m2 g1.26
Fine tuning of synthesis, activation, and handling conditions
to realize the full potential of MOFs is a recurring difficulty in
the field.
3.1.4 MOF example 3: MMOF-74/CPO-27-M (M = Mg,
Mn, Co, Ni, Zn). The MMOF-74 series of MOFs, with high
density of UMCs, were evaluated as methane storage materials.214
It was calculated that the adsorption of one methane molecule
per UMC could generate methane storage capacities in the
range of 160–174 v/v. The isostructural series, with one-dimensional
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channels of approximately 13.6 Å diameters, were synthesized
and specifically studied to elucidate the role of UMCs in
methane uptake capabilities.
Of the materials in the series, NiMOF-74 performed best as
a methane adsorbent with an absolute uptake capacity of
B200 v/v, Fig. 6. However, the high heats of adsorption on
the UMCs, as determined from neutron diffraction studies,
lead to high loading at low pressures and, therefore, retention
of a large amount of methane at low pressures (B105 v/v at
5 bar).214 The dependence of the identity of the UMC on
methane binding energy was discovered to be much weaker
than that of hydrogen binding energies.239 This was attributed
to the larger size and geometrical constraint of CH4 molecules,
increasing the distance between a metal center and a methane
molecule and, thereby, decreasing interaction potential. A
potential setback involving the use of MOFs with high
densities of UMCs is that, typically, only one methane molecule may interact with one UMC. Additionally, increasing the
density of UMCs induces a significant increase in framework
mass. This leads to realization of low gravimetric loading of
methane within the framework. Since the ligand currently
plays little role in the adsorption of methane within the
MMOF-74 series, one method for enhancing uptake capacities
Fig. 6 (a) Excess CH4 adsorption isotherms of M2(dhtp) at 298 K.
(b) The experimental Qst of Ni2(dhtp) and Zn2(dhtp) (the error bar is
5%). The Qst’s of Mg2(dhtp), Mn2(dhtp), and Co2(dhtp) fall between
the two curves and, thus, are not shown for clarity. The Qst’s of MOF-5
(from ref. 14) are also plotted for comparison. Reprinted with permission
from ref. 214. Copyright 2009 American Chemical Society.
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is to incorporate into the framework ligands with functional
groups which may interact more strongly with methane, such
as pendant lipophilic alkyl chains.
3.1.5 MOF example 4: UTSA-20. With the design principles
in mind to (1) immobilize a high-density of UMCs and (2)
construct suitable pore spaces within a MOF for methane to
adsorb, the MOF UTSA-20 was formed from the combination
of 3,3 0 ,300 ,5,5 0 ,500 -benzene-1,3,5-triyl-hexabenzoate (bhb6) and
dicopper paddlewheel SBUs.238 Two different types of onedimensional channels are formed within the framework with
UMCs exposed to the pores: rectangular pores with dimension
3.4 4.8 Å2 and cylindrical pores with a diameter of 8.5 Å. The
BET surface area calculated from the N2 sorption isotherm at
77 K (1156 m2 g1) falls within the ‘‘moderate’’ surface area
range that appears optimal for methane storage applications.
Additionally, the presence of a high density of UMCs and small
pores make UTSA-20 a very promising potential methane
storage material.
The methane storage density at 300 K and 35 bar in UTSA-20
was determined to be 0.222 g cm3 (178 v/v), nearly reaching the
density of compressed methane at 300 K and 340 bar.238 The
storage capacity at 150 K and 5 bar is equivalent to 89% of that
of liquid methane and exhibits a high isosteric heat of adsorption
of 17.7 kJ mol1 at zero coverage. Since it was discovered that
full occupation of the UMCs by methane would only attribute to
approximately half of the observed methane stored, GCMC
calculations were utilized to identify the other binding sites within
the framework. The pore spaces between bhb6 linkers within
the channels were discovered to have short distances between
adjacent linkers that would allow methane molecules to be
‘‘sandwiched’’ between two bhb6 potential surfaces, Fig. 7.
The combination of UMCs and this second adsorption site
was calculated to contribute to B90% of the experimental
uptake at 298 K and 35 bar. The remaining B10% may be
easily attributed to secondary binding sites which exhibit lower
heats of adsorption.
3.1.6 MOF example 5: PCN-6 series. Generally, to
synthesize high surface area MOFs it is necessary to increase
the length of organic linkers.240–242 However, doing so tends to
decrease the stability of the framework and many materials
with extended linkers collapse upon guest removal. As a means
to increase surface area and pore volume while maintaining
structural integrity it was proposed that MOFs built upon
in situ formed large coordination polyhedra (cages) accessible
through small pore apertures could stabilize larger pore
voids.243 Cuboctahedral coordination cages, constructed with
12 dimetal paddlewheel clusters and 24 isophthalate moieties,
have been identified as very common structural units in MOF
structures,244–250 and they serve as stabilizing units in the
PCN-6 series due to the small pore space and generation
of small pore apertures to larger cages.27 The design of
extended hexatopic linkers with C3 symmetry combined with
dicopper paddlewheel clusters led to the realization of four
isoreticular MOFs with framework formula Cu3(L) (L = btei,
PCN-61; ntei, PCN-66; ptei, PCN-68; ttei, PCN-610), Fig. 8.
The PCN-6 MOFs exhibit impressive pore volumes and
surface areas, with PCN-68 having a Langmuir surface
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Fig. 7 (a) Probability distribution of the CH4 center of mass in
UTSA-20 ([0 0 1] view), obtained from GCMC simulation at 298 K
and 10 bar. The red regions represent the places where methane
molecules are heavily populated in the MOF structure. Note that
the open Cu site is preoccupied with CH4 molecules to focus our effort
on the search for other strong methane adsorption sites. (b) The pore
surface of the interconnected channel pores in UTSA-20 (derived using
N2 as probe molecules, based on vdW interactions), with adsorbed
methane at the linker channel site (derived from DFT-D calculations).
The channel width along the c axis matches well with the size of the
adsorbed methane molecules, leading to enhanced vdW interaction
(methane molecules are shown in space-filling representation for
clarity). Reprinted with permission from ref. 238. Copyright 2011
John Wiley and Sons.
area >6000 m2 g1, among the highest reported for MOFs.251
While PCN-610 is expected to have an even higher surface
area than PCN-68, the organic linker is too long for the
framework to be stabilized by the cuboctahedral cages and
collapses upon guest solvent removal.
Fig. 8 (a) Nanoscopic ligands btei (PCN-61), ntei (PCN-66), ptei
(PCN-68), and ttei (PCN-610); (b) (3,24)-connected network in PCN-68;
(c) 3D polyhedra packing in PCN-68. Reprinted with permission from
ref. 27. Copyright 2010 John Wiley and Sons.
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The methane uptake capacities of PCN-61, -66, and -68
were measured at 298 K and up to 100 bar, Fig. 9a.27 As
expected, the gravimetric uptake at high pressures (>60 bar) is
dominated by effects of surface area and pore volume, with
PCN-68 showing the greatest uptake. However, in the low to
medium pressure regime (o30 bar), PCN-61 exhibits greater
uptake capacity than the two isoreticular MOFs with greater
surface areas, Fig. 9b. This phenomenon was attributed to
stronger methane affinity of the framework likely caused by
small pore spaces that exhibit better CH4–framework potential
overlap. Using the crystal density of each framework, the
volumetric capacities of PCN-61, -66, and -68 were estimated to
be 145 v/v, 110 v/v, and 99 v/v, respectively. This trend follows the
variance in crystal density, as expected (0.56 g cm3 for PCN-61,
0.45 g cm3 for PCN-66, and 0.38 g cm3 for PCN-68).
This previous study emphasized the necessity to concentrate
not solely on increasing surface area of porous materials to
achieve high volumetric methane uptake but to maintain a
balance between porosity, density, pore size, surface area, and
other factors.
3.2 Porous organic polymers (POPs)
Concerns over stability and cost associated with the application of MOFs in methane adsorption have led to the evaluation of POPs as methane sorbents. Their tolerance of water
and metal-free design make POPs very attractive options in
applications. Furthermore, many POPs exhibit exceptionally
high surface areas and low framework density, which make
Fig. 9 (a) Gravimetric and (b) volumetric capacities of CH4 adsorption
in the PCN-6 series at 298 K. The inset in (a) shows the medium-pressure
region enlarged. Reprinted with permission from ref. 27. Copyright 2010
John Wiley and Sons.
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them ideal in the gravimetric storage of gases.252–254 However,
these same features pose a significant hurdle to overcome in
terms of volumetric storage capacity.
Due to the formation of strong covalent bonds, amorphous
POPs often require optimization of synthesis conditions to
maximize the surface area and porosity of the material. In this
aspect, the resemblance to traditional organic polymers is very
apparent. Unlike amorphous POPs, COFs are typically formed
from dynamic covalent bonds (B–O bonds, for instance) to
facilitate the formation of crystalline phases;255 however, the
dynamic nature of the bonds leaves COFs significantly more
susceptible to hydrolysis.256,257
Several POPs that exhibit high gravimetric methane storage
capacities are presented below and methane uptake data
collected in Table 2. Although experimental results still remain
short of volumetric storage goals, promising approaches including
surface modification and compression are discussed.
5–35 bar, with a total uptake of 206 v/v.259 This deliverable
amount shows that COF-103-Eth-trans can store an amount
of methane equivalent to 5.6 times that of methane in the
pure gas phase at the same pressure. COF-102-Ant performs
similarly, 215 v/v total uptake and 180 v/v deliverable, from
5–35 bar. However, at 300 bar COF-102-Ant has a deliverable
volume of methane (258 v/v) less than that of pure methane
(263 v/v), whereas MOF-177 is calculated to have a deliverable
capacity of 336 v/v at the same pressure.
To further enhance the methane capacity at readily applicable pressure, theoretical study indicates that Li+ cation
doping of COFs can significantly strengthen the binding of
methane to the materials because of London dispersion and
induced dipole interactions between Li+ cation and methane
molecules.260 At 298 K and relatively low pressures (o50 bar),
the methane uptakes of Li+ doped COFs nearly doubled,
compared to the corresponding non-doped frameworks. The
total volumetric uptakes of methane in Li+ doped COF-102
and COF-103 reach 327 and 315 v/v, respectively, at 298 K
and 35 bar. In addition, the Li+ doped COFs also exhibit
ultrahigh excess methane uptakes, which is evidently originating
from the strong affinity as a result of Li+ doping. The excess
volumetric methane uptakes of Li+ doped COF-102 and COF-103
reach 303 and 290 v/v, respectively, at 298 K and 35 bar. It is
concluded that functionalizing the building blocks of COFs with a
Li atom or a Li+ cation could result in much stronger affinity to
methane, therefore effectively improving the storage capabilities.
The above-mentioned theoretical study sheds light on
approaches to enhance methane storage at ambient temperatures and 35 bar. These results provide useful information on
modification of not only COFs but also other porous materials
for further improving experimental methane storage capacity.
3.2.1 Covalent organic frameworks (COFs). A combined
computational–experimental study has revealed that covalent
organic frameworks (COFs) show great promise as methane
sorbents.258 COF-1 was identified as a material that can
adsorb up to 195 v/v at 295 K and 30 bar, excess adsorption,
based on computational measurements. Interestingly, upon
increasing the pressure further, no increase in methane adsorption is observed. Because of the small pores in COF-1, the pores
are quickly occupied by incoming guest molecules at low
pressures. Higher pressures may not compact the gas any more
than already observed in the framework, leading to lower
efficiency than what is observed at 30 bar. The larger pore,
three-dimensional COFs, COF-102 and COF-103, on the other
hand, do not reach a plateau in methane adsorption until above
100 bar and exhibit methane working capacities of 230 and
234 v/v, respectively (Fig. 10; working capacity is defined as
the volume adsorbed from 5 to 100 bar; volumetric capacities
calculated from single crystal density).
Furthermore, the functionalized COF-103-Eth-trans has
been calculated to deliver up to 192 v/v over the range of
Table 2
Surface area, pore volume, methane storage properties under specific conditions for porous organic polymers
Surface area m2 g1
Compound
wt% =
Conditions
BET
Lang.
Pore volume
cm3 g1
P/bar
T/K
Methane uptake
capacity/wt%a
DHads/kj mol1
(zero coverage)
750
1670
750
1350
1760
3620
3530
970
1990
980
1400
2080
4650
4630
0.3
1.07
0.32
0.69
1.44
1.55
1.54
35
35
35
35
35
35
35
(85)
(85)
(85)
(85)
(85)
(85)
(85)
298
298
298
298
298
298
298
3.9 (4.3)b
8.2 (11.2)b
6.2 (6.5)b
8.0 (10.2)b
7.4 (11.1)b
15.8 (19.6)b
14.9 (18.7)b
17
8.5
19
12
8.5
8.6
9.5
1904
1307
963
1366
2992
2001
1210
2096
0.54
0.36
0.32
0.55
15
15
15
15
(20)
(20)
(20)
(20)
298
298
298
298
6.6
5.9
4.9
6.5
1249
1764
2840
6461
827
2790
5323
10 063
0.45
1.26
1.7
3.04
35
35
35
35 (55)
295
295
295
295
7.6b
9.8b
12.2b
21.5 (28.0)b
Ref.
253
COFs
COF-1
COF-5
COF-6
COF-8
COF-10
COF-102
COF-103
HCPs
HCP-1
HCP-2
HCP-3
HCP-4
PPNs
PPN-1
PPN-2
PPN-3
PPN-4
a
3.2.2 Hypercrosslinked polymer networks (HCPs). Methane
sorption has been much less widely studied in noncrystalline
organic polymers. However, the isosteric heats of adsorption for
methane in most of these materials are around 15–20 kJ mol1
(Table 2), which is deemed as the appropriate range for methane
142
(7.7)c
(6.7)c
(5.3)c
(6.9)c
20.8
25
massCH4 adsorbed
masssorbent þmassCH4 adsorbed
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c
100%.
b
18.1
16.4
15.2
Excess uptake. c Total (absolute) uptake.
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Fig. 11 Methane uptake isotherms for porous organic polymers at
298 K and 35 bar. Data extracted from Table 2 (PPNs at 295 K, HCPs
at 36 bar).
Fig. 10 Predicted deliverable volumetric methane isotherms (the
difference between the total amount at pressure p and that at 5 bar)
at 298 K for COFs. Here the black dashed line indicates the uptake for
free CH4 gas. MOF-177 uptake is added for comparison. Modified and
reproduced with permission from ref. 258. Copyright 2010 American
Chemical Society.
storage at close to ambient temperatures, as the optimal value
of the heat of adsorption was calculated to be 18.8 kJ mol1 by
Bhatia and Myers.261 Considering the relatively easy scale-up,
organic polymers could have much to offer here.
Prepared by Friedel–Crafts alkylation of bischloromethyl monomers such as dichloroxylene (DCX), and 4,40 -bis(chloromethyl)1,10-biphenyl (BCMBP), a series of HCPs were obtained either as
precipitated powders or as monolithic blocks.142 These HCPs were
shown to adsorb up to 5.2 mmol g1 (116 cm3 g1) of methane
at 298 K and 20 bar, which is comparable with many crystalline porous systems. It is noteworthy to point out that,
compared to MOFs, these polymers not only have high surface
area (SBET: 1900 m2 g1 and SLangmuir: 3000 m2 g1), but also can
be produced by simple and scalable steps. Most importantly, these
materials usually have much higher physicochemical stability due
to covalent bonding in the construction of the network. Isosteric
heat of adsorption for methane on microporous polydichloroxylene (HCP–3(DCX(100)) was measured to be 20.8 kJ mol1 at
low-loading, which is in good agreement with atomistic simulation
results, the maximum value in the simulated distribution of
methane–polymer interaction energy was found to be around
22 kJ mol1.
3.2.3 Porous polymer networks (PPNs). In addition to high
affinity to methane, large surface area and high micropore
volume are the other two most important factors that should
be taken into consideration in terms of material design to
improve methane uptake capacity. Fig. 11 shows the methane
gravimetric uptake at 298 K and 35 bar for various POPs as a
function of apparent BET surface area. In general, the amount
of methane uptake in the materials increases with increasing
surface area. To maximize surface area of organic polymers,
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the two most important criteria are: (1) highly efficient polymerization reaction, such as Yamamoto or Eglinton homocoupling, which can help to form highly connected frameworks
with sufficient molecular weight; and (2) rigid monomeric
units with reaction sites oriented in different directions, such
as tetrahedral monomers, which can help to form default
diamondoid framework topology, thereby creating widely
open and interconnected pores without the formation of ‘‘dead
space’’. Based on these two criteria, the Zhou group successfully synthesized a series of PPNs with exceptionally high
surface areas and microporous nature.136
Among them, PPN-4, synthesized from tetrakis(4-bromophenyl)silane through Yamamoto homo-coupling, exhibits a
record high BET surface area of 6461 m2 g1, which is close
to the predicted value based on the non-interpenetrated
molecular model.25 PPN-4 can retain its structural integrity
after being exposed to air for one month, which is indicated by
virtually no drop of N2 uptake capacity at 77 K after simple
reactivation by heating under vacuum. In terms of methane
uptake capacity, PPN-4 can adsorb up to 17.1 mmol g1 at
295 K and 35 bar, which transcends all reported organic
porous materials, to date. This gravimetric value is much
higher than that of PCN-14 (total: 12 mmol g1 at 290 K
and 35 bar), which is the current record holder in terms of
volumetric methane uptake capacity. For a material with a
density of 1.0 g cm3, a methane uptake of 7.9 mmol g1
would be required to reach a volumetric value of 180 v/v.131 As
many organic polymers have very low densities, the amount
adsorbed would need to be higher; hence, for the PPN-4
network with an approximate density of 0.2 g cm3, a molar
uptake of 39.5 mmol g1 is required to reach 180 v/v. Based on
this approximate density, the uptake of 17.1 mmol g1 corresponds to only 77 v/v. However, it is noteworthy to point out
that, due to its exceptionally high thermal and chemical
stability, the preliminary data indicate that PPN-4 could be
compressed to half its size without any obvious loss of its
porosity. Thus, the volumetric uptake capacity of methane
could be increased several times by appropriate compression.
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In summary, organic polymers, similarly to MOFs, appear to
have promise for methane storage. It is currently unclear,
though, if these materials can compete on cost grounds
with sorbents such as activated carbon. Notwithstanding cost
concerns, we think it is necessary to point out that the cost
cannot be calculated easily from lab-scale experiments, it
would ultimately be linked to recyclability and lifetime, etc.
when scaled up for applications.
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4
Design principles for optimal methane sorbents
The majority of MOFs and POPs that have been reported in
the literature are composed of micropores, with a limited
number of materials containing mesopores (2 nm o pore
diameter o 50 nm). Mesopores, however, are inefficient at
adsorbing methane due to a decrease in the interactions
between methane guest molecules and the pore surfaces. This
leads to a characteristic more similar to an empty tank and
does not significantly enhance the methane packing density. It
should be noted, however, that the functionalization of mesoporous materials can serve to effectively reduce the pore size
and increase methane affinity of the frameworks, whereas similar
functionalization of microporous materials can potentially result
in blockage of pores by the additional functional group.
The adsorption of methane in porous sorbents occurs
through weak dispersive forces (physisorption). The surface
area of the sorbent tends to correlate with the quantity of
observed physisorption; higher surface area materials typically
exhibit greater gas uptake. However, at least in the case of
methane sorption, the accessible surface area appears to play
less of a decisive role in volumetric and gravimetric capacity.69
This trend is further emphasized in Table 1. Additionally, a
number of studies have shown that a cooperative interplay
between the accessible surface area, pore volume, isosteric heat
of adsorption, and pore topology exists to determine the CH4
storage or deliverable capacity in porous sorbents.17,262,263
Unlike hydrogen, the interaction energy of methane with
porous materials is already at a reasonable level. The problem
currently facing the implementation of MOFs in ANG storage
devices is the volumetric capacity of methane in such a system.
Further developments are necessary to enhance the packing
density of methane molecules in the porous sorbent. Additionally, it
is not enough to only increase the excess or total uptake of methane
in adsorbents; the working, or deliverable, quantity of methane
must be enhanced. This is the volume of methane that will be
released from the system during use. Obviously, in a fuel system the
pressure will not reduce to a level below atmospheric pressure, and
typical working pressures for internal combustion engines are
around 5 bar. Therefore, for vehicular ANG technologies, the
deliverable amount of methane may be referred to as the amount of
methane adsorbed between 5 bar and the upper working limit of
the system, preferably r35 bar, so as to not require heavy, thickwalled cylinders. To maximize the deliverable capacity of the
sorbent, it is necessary to minimize the amount of methane stored
at unusable pressures, i.e. below B5 bar. Therefore, a trade-off
between total storage capacity and deliverable capacity is observed,
whereby increased isosteric heat of adsorption may enhance total
storage capacity but decrease deliverable capacity by increasing the
amount of methane retained at low pressures.
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In MOFs, methane has been identified to preferentially
adsorb in the tight fitting spaces created from close proximity
of large ligands to one another, after occupying the UMCs.
The enhancement in the density of UMCs and formation of
pore spaces tailored to a size similar to that of the kinetic
diameter of methane, or twice the kinetic diameter, through
incorporation of large aromatic or methyl-substituted ligands
should significantly increase the uptake capacity of future
MOFs. From the previous section, it can be concluded that
a good ligand candidate for methane storage purposes should
have a large aromatic ring system or pendant lipophilic
groups, so that ligands in the MOFs generated have higher
affinity towards methane. Additionally, large surface area and
high micropore volume should be considered. However, it has
been observed that increasing the gravimetric surface area of
MOFs is beneficial until a certain point is reached
(B2500–3000 m2 g1), above this point leads only to loss of
volumetric methane storage capabilities.235 Furthermore,
increasing the pore volume too far beyond the size of two
methane molecules is also detrimental to the storage capacity
of MOFs. These larger pores are not effective at binding
methane due to the large distance between pore surfaces,
leading to a decrease in potential overlap between host and
guest and fewer methane molecules interacting with pore
surfaces. At higher pressure, such as 100 bar, the accessible
volume within the pores of the framework becomes the most
significant factor to methane uptake. This is within the region
in which CH4–CH4 interactions become prevalent and
CH4–pore wall interactions are less significant. The methane
uptake enhancement through use of adsorbents in this region
becomes less substantial and approaches equivalency with that
of pure methane at the same pressure.258
The use of dendritic ligands which increase the density of
UMCs and create small pores and cages may serve as a means
for increasing the storage capacity of MOFs by enhancing
framework–guest interactions. The alignment of UMCs
through incorporation of isophthalate moieties paired with
dicopper paddlewheel SBUs in a MOF has been shown to
significantly enhance the binding affinity and storage of hydrogen by focusing the highly directional UMC–guest interactions
to an optimal void space where guests can adsorb.264 However, the data investigating the role of UMCs in methane
sorption are somewhat contradictory. On the one hand,
UMCs have been shown to be the primary binding sites for
methane in the MMOF-74 series, and contribute to a significant quantity of stored methane;214 whereas other studies have
shown that UMCs are the primary binding site only in the low
pressure/low temperature regime.232 Even if UMCs do not
significantly enhance methane storage capacities at ambient
temperatures, the isophthalate–paddlewheel combination typically
forms microporous cages that create small spaces in which guest
molecules may interact strongly with pore surfaces. Both of these
enhancements together may produce materials with high methane
adsorption capacity by maximizing UMC–methane interactions,
as well as potential overlap between framework ligands and
methane guest molecules.
The crystalline property of MOFs makes them good models
for molecular simulation studies of their methane uptake
capacities. A recent computational study undertook a screening
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process for identifying the potential of hypothetical MOFs to
adsorb methane, with over 300 candidate MOFs discovered to
be able to surpass 180 v/v.235 The expanded study simplified
the process of predicting possible MOF structures and, therefore, allowed the analysis of more complicated systems than
previous studies. Many of the high capacity materials identified
through this computational screening process contained free
methyl groups thought to be able to interact with incoming
guest methane molecules, increasing the overall uptake capacity. Inspection of the nine top performing MOFs (>230 v/v
capacity) from the Hypothetical Metal–Organic Frameworks
Database generated by the Snurr lab235 reveals that MOFs with
channels defined by large, planar aromatic surfaces and pore
sizes centered around B4 or B7.75 Å should exhibit exceptional methane storage capacity at 298 K and 35 bar, both in
terms of gravimetric and volumetric capacities. Considering the
kinetic diameter of methane, 3.8 Å, this pore size distribution
intuitively makes sense. Targeting the synthesis of porous
frameworks with high surface area and pores close to the size
of one or two methane molecules is the most straightforward
method for sustaining CH4–framework interactions upon
increased loading. Additionally, by targeting pore sizes very
near integer multiples of the kinetic diameter of a methane
molecule minimizes the amount of unusable ‘‘dead’’ space
within the pores. For instance, a pore size of 9.5 Å may
accommodate 2.5 methane molecules, but since only whole
molecules may be included, a large amount of free volume is
left unoccupied. The increased distance between pore surfaces
also leads to a reduction in CH4–CH4 interactions between
adsorbed molecules.
Furthermore, as has been observed in the studies of carbonaceous materials for methane storage, low packing densities
significantly adversely affect the volumetric uptake capacity of
porous materials. This remains a relatively unexplored topic in
the study of advanced porous materials, but initial densification studies have shown decreased gravimetric uptake capacity
due to reduction in micropore volume resulting from framework
collapse. As such, additional investigations into engineering
methods for enhancing the packing density of advanced porous
materials while maintaining micropore volume are necessary.
5
Challenges, outlook, and conclusions
The greatest challenges facing the efficient storage of methane
in porous materials involve designing materials that maintain
effective interaction sites at higher pressures and increasing the
packing density of materials so as to achieve high volumetric
capacities. Currently, porous sorbents tend to strongly adsorb
methane at low pressures (o1 bar), occupying a large portion
of effective surface area and binding sites. As the pressure is
further increased, CH4–CH4 interactions tend to dominate the
storage process and, therefore, exhibit low isosteric heats of
adsorption upon greater loading. To increase the magnitude of
CH4–CH4 interactions, new strategies must be developed that
can effectively pack methane within the pores of a sorbent. It
can be imagined that two CH4 molecules strongly adsorbed on
pore surfaces opposite of one another could have greater
adsorption influence on a third CH4 molecule positioned
between the two than randomly distributed gas molecules.
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Chem. Soc. Rev., 2012, 41, 7761–7779
This influence should be enhanced even further by the ‘‘free’’
CH4 molecule interacting with a greater number of surfacebound CH4 molecules, emphasizing the potential of small
cages to increase methane capacities. To this end, it is of
exceptional importance to finely tune the pore shapes and sizes
of porous sorbents.
In particular, the application of ANG as a vehicular fuel
storage system must address several additional factors. These
include impurities in NG lines, which vary based upon regional
location, and heat management during charging and discharging.
Impurities can substantially deteriorate the adsorption capacity
for methane in ANG systems upon multiple adsorption and
desorption cycles due to retention of other gases.265 Water and
carbon dioxide present the biggest challenges in terms of
impurities in NG lines, due to high heats of adsorption for
both species in porous materials, as well as longer chain
alkanes, which can all block pores within the sorbents.
AGLARG has previously addressed the issue of impurities
on a prototype ANG storage tank through the use of a
preadsorption system or ‘‘guard bed’’.266,267
Guard bed technologies are designed to serve as a filter
to purify NG entering the fuel system by removing those
impurities that exhibit stronger binding energies than methane
toward the sorbent in the primary fuel tank. Guard beds could
be composed of mixed-matrix systems so as to adsorb a
maximum amount of impurities from the NG that can be
released to the engine during discharge. To be effective, a
guard bed must have a strong affinity toward the impurities, as
they will be present in trace amounts with relatively low partial
pressures, as well as high adsorption capacity. However,
interaction energies that are too high will adversely affect
desorption rates and require frequent regeneration or replacement of the guard bed. Therefore, diligent selection of porous
materials for such a system would be required to meet all the
necessary demands.
Kinetics and heat exchange during charging and discharging
are also of importance in the design of porous sorbents for
vehicular ANG fuel storage. Adsorption is an exothermic
process and, naturally, desorption is endothermic. Maintaining
isothermic conditions or cooling during charging while heating
when discharging is likely necessary to maximize deliverable
capacity of the system. Additionally, insufficient thermal management during discharge may reduce the kinetics of gas
diffusion through the porous sorbent, reducing the amount of
fuel provided to the engine. Adsorbents should possess high
heat capacity and thermal conductivity values. However, since
sorbents with high capacities toward methane possess large
inherent pore volumes, they will likely exhibit poor heat transfer
characteristics.265 Currently, little data evaluating heat transfer
properties of advanced porous materials have been reported,
but is expected to become a more active research area.
The suggested use of advanced porous materials for
methane storage has received wide attention due to growing
concerns over the energy environment and economy in the
world. While use of porous materials in hydrogen storage
devices is yet in the distant future to be fully realized, the
storage of methane at relatively low pressure and ambient
temperature in porous sorbents, specifically MOFs and POPs,
is presently an achievable goal. Several advanced porous
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materials that exhibit exceptional storage potential have been
synthesized and evaluated.
Ongoing research involving computational screening of
both hypothetical and previously reported materials should
play an important role in the determination of potential
systems to be experimentally validated and studied. Experimental evaluation of the impacts of pendant lipophilic groups
in MOFs on the binding of methane is necessary and presents
a hopeful step forward in the design of porous materials for
the adsorption of methane. The implementation of materials
that can efficiently store methane for personal use in vehicular
or in-home fuel systems is near the cusp of being realized. At
this stage in the development of methane storage technologies
it is necessary for computational and experimental chemists,
chemical engineers, and materials scientists to work together
to harness the full potential of porous adsorbents.
Acknowledgements
This work was supported by the U.S. Department of Energy (DOE
DE-SC0001015, DE-FC36-07GO17033, and DE-AR0000073),
the National Science Foundation (NSF CBET-0930079), and
the Welch Foundation (A-1725).
References
1 M. Gallo and D. Glossman-Mitnik, J. Phys. Chem. C, 2009, 113,
6634–6642.
2 S. A. Rackley, Carbon Capture and Storage, Butterworth-Heinemann/
Elsevier, Boston, 2010.
3 Carbon Capture: Sequestration and Storage, ed. R. E. Hester and
R. M. Harrison, RSC Pub., Cambridge, UK, 2010.
4 S. A. Roosa and A. G. Jhaveri, Carbon Reduction: Policies,
Strategies and Technologies, Fairmont Press, Lilburn, GA, 2009.
5 Carbon Capture and Sequestration: Integrating Technology, Monitoring
and Regulation, ed. E. J. Wilson and D. Gerard, Blackwell Pub., Ames,
Iowa, 2007.
6 J. Yang, A. Sudik, C. Wolverton and D. J. Siegel, Chem. Soc.
Rev., 2010, 39, 656–675.
7 J. Graetz, Chem. Soc. Rev., 2009, 38, 73–82.
8 L. J. Murray, M. Dincă and J. R. Long, Chem. Soc. Rev., 2009,
38, 1294–1314.
9 L. Schlapbach and A. Züttel, Nature, 2001, 414, 353–358.
10 K. L. Lim, H. Kazemian, Z. Yaakob and W. R. W. Daud, Chem.
Eng. Technol., 2010, 33, 213–226.
11 R. B. Getman, Y.-S. Bae, C. E. Wilmer and R. Q. Snurr, Chem.
Rev., 2012, 112, 703–723.
12 M. P. Suh, H. J. Park, T. K. Prasad and D.-W. Lim, Chem. Rev.,
2012, 112, 782–835.
13 U. S. E. P. Agency, Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990–2007, EPA 430-R-09-004, 2009.
14 J. StephensonInternational Association of NGVs1993.
15 V. C. Menon and S. Komarneni, J. Porous Mater., 1998, 5, 43–58.
16 D. J. Collins, S. Ma and H.-C. Zhou, Metal-Organic Frameworks,
John Wiley & Sons, Inc., 2010, pp. 249–266.
17 T. Düren, L. Sarkisov, O. M. Yaghi and R. Q. Snurr, Langmuir,
2004, 20, 2683–2689.
18 X. Lin, N. Champness and M. Schröder, in Top. Curr. Chem.,
ed. M. Schröder, Springer, Berlin/Heidelberg, 2010, vol. 293,
pp. 35–76.
19 S. Ma, D. Sun, J. M. Simmons, C. D. Collier, D. Yuan and
H.-C. Zhou, J. Am. Chem. Soc., 2008, 130, 1012–1016.
20 W. Zhou, Chem. Rec., 2010, 10, 200–204.
21 D. Lozano-Castelló, J. Alcañiz-Monge, M. A. de la Casa-Lillo,
D. Cazorla-Amorós and A. Linares-Solano, Fuel, 2002, 81,
1777–1803.
22 H.-C. Zhou, J. R. Long and O. M. Yaghi, Chem. Rev., 2012, 112,
673–674.
This journal is
c
The Royal Society of Chemistry 2012
23 A. Bétard and R. A. Fischer, Chem. Rev., 2012, 112, 1055–1083.
24 M. O’Keeffe and O. M. Yaghi, Chem. Rev., 2012, 112, 675–702.
25 D. Yuan, W. Lu, D. Zhao and H.-C. Zhou, Adv. Mater., 2011, 23,
3723–3725.
26 X. Lin, I. Telepeni, A. J. Blake, A. Dailly, C. M. Brown,
J. M. Simmons, M. Zoppi, G. S. Walker, K. M. Thomas,
T. J. Mays, P. Hubberstey, N. R. Champness and M. Schröder,
J. Am. Chem. Soc., 2009, 131, 2159–2171.
27 D. Yuan, D. Zhao, D. Sun and H.-C. Zhou, Angew. Chem., Int.
Ed., 2010, 49, 5357–5361.
28 M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter,
M. O’Keeffe and O. M. Yaghi, Science, 2002, 295, 469–472.
29 D. Zhao, D. J. Timmons, D. Yuan and H.-C. Zhou, Acc. Chem.
Res., 2010, 44, 123–133.
30 K. J. Gagnon, H. P. Perry and A. Clearfield, Chem. Rev., 2012,
112, 1034–1054.
31 N. Stock and S. Biswas, Chem. Rev., 2012, 112, 933–969.
32 J.-P. Zhang, Y.-B. Zhang, J.-B. Lin and X.-M. Chen, Chem. Rev.,
2012, 112, 1001–1033.
33 R.-Q. Zou, H. Sakurai, S. Han, R.-Q. Zhong and Q. Xu, J. Am.
Chem. Soc., 2007, 129, 8402–8403.
34 H. Fu, Y. Lu, Z. Wang, C. Liang, Z.-m. Zhang and E. Wang,
Dalton Trans., 2012, 41, 4084–4090.
35 X. Gu, Z.-H. Lu, H.-L. Jiang, T. Akita and Q. Xu, J. Am. Chem.
Soc., 2011, 133, 11822–11825.
36 W. Lin, J. Solid State Chem., 2005, 178, 2486–2490.
37 D.-D. Liang, S.-X. Liu, F.-J. Ma, F. Wei and Y.-G. Chen, Adv.
Synth. Catal., 2011, 353, 733–742.
38 S. Wang, L. Li, J. Zhang, X. Yuan and C.-Y. Su, J. Mater. Chem.,
2011, 21, 7098–7104.
39 F. Yu, P.-Q. Zheng, Y.-X. Long, Y.-P. Ren, X.-J. Kong,
L.-S. Long, Y.-Z. Yuan, R.-B. Huang and L.-S. Zheng, Eur. J.
Inorg. Chem., 2010, 4526–4531.
40 A. Corma, H. Garcia and F. X. Llabres i Xamena, Chem. Rev.,
2010, 110, 4606–4655.
41 A. Dhakshinamoorthy, M. Alvaro and H. Garcia, Chem.–Eur. J.,
2010, 16, 8530–8536.
42 H.-L. Jiang, B. Liu, T. Akita, M. Haruta, H. Sakurai and Q. Xu,
J. Am. Chem. Soc., 2009, 131, 11302–11303.
43 D. Jiang, T. Mallat, F. Krumeich and A. Baiker, J. Catal., 2008,
257, 390–395.
44 K. C. Szeto, K. O. Kongshaug, S. Jakobsen, M. Tilset and
K. P. Lillerud, Dalton Trans., 2008, 2054–2060.
45 Y. Lu, M. Tonigold, B. Bredenkötter, D. Volkmer, J. Hitzbleck
and G. Langstein, Z. Anorg. Allg. Chem., 2008, 634, 2411–2417.
46 A. D. Burrows, C. G. Frost, M. F. Mahon, M. Winsper,
C. Richardson, J. P. Attfield and J. A. Rodgers, Dalton Trans.,
2008, 6788–6795.
47 H.-L. Jiang and Q. Xu, Chem. Commun., 2011, 47, 3351–3370.
48 V. Isaeva and L. Kustov, Pet. Chem., 2010, 50, 167–180.
49 J. Lee, O. K. Farha, J. Roberts, K. A. Scheidt, S. T. Nguyen and
J. T. Hupp, Chem. Soc. Rev., 2009, 38, 1450–1459.
50 F. X. Llabrés i Xamena, O. Casanova, R. Galiasso Tailleur,
H. Garcia and A. Corma, J. Catal., 2008, 255, 220–227.
51 Q.-R. Fang, D.-Q. Yuan, J. Sculley, J.-R. Li, Z.-B. Han and
H.-C. Zhou, Inorg. Chem., 2010, 49, 11637–11642.
52 D. Farrusseng, S. Aguado and C. Pinel, Angew. Chem., Int. Ed.,
2009, 48, 7502–7513.
53 M. Ranocchiari and J. A. v. Bokhoven, Phys. Chem. Chem. Phys.,
2011, 13, 6388–6396.
54 M. Yoon, R. Srirambalaji and K. Kim, Chem. Rev., 2012, 112,
1196–1231.
55 D. F. Sava, V. C. Kravtsov, F. Nouar, L. Wojtas, J. F. Eubank
and M. Eddaoudi, J. Am. Chem. Soc., 2008, 130, 3768–3770.
56 B. F. Hoskins and R. Robson, J. Am. Chem. Soc., 1990, 112,
1546–1554.
57 G. B. Gardner, D. Venkataraman, J. S. Moore and S. Lee,
Nature, 1995, 374, 792–795.
58 E. Lee, J. Kim, J. Heo, D. Whang and K. Kim, Angew. Chem.,
Int. Ed., 2001, 40, 399–402.
59 S. Yang, G. S. B. Martin, J. J. Titman, A. J. Blake, D. R. Allan,
N. R. Champness and M. Schröder, Inorg. Chem., 2011, 50,
9374–9384.
60 R.-X. Yao, X. Xu and X.-M. Zhang, Chem. Mater., 2011, 24,
303–310.
Chem. Soc. Rev., 2012, 41, 7761–7779
7775
Downloaded by Texas A & M University on 22 February 2013
Published on 18 September 2012 on http://pubs.rsc.org | doi:10.1039/C2CS35251F
View Article Online
61 M. D. Ward, Science, 2003, 300, 1104–1105.
62 J. L. C. Rowsell and O. M. Yaghi, Angew. Chem., Int. Ed., 2005,
44, 4670–4679.
63 X. Lin, J. Jia, P. Hubberstey, M. Schröder and N. R. Champness,
CrystEngComm, 2007, 9, 438–448.
64 R. E. Morris and P. S. Wheatley, Angew. Chem., Int. Ed., 2008,
47, 4966–4981.
65 D. J. Collins and H.-C. Zhou, J. Mater. Chem., 2007, 17,
3154–3160.
66 M. Dincă and J. R. Long, Angew. Chem., Int. Ed., 2008, 47,
6766–6779.
67 J. Sculley, D. Yuan and H.-C. Zhou, Energy Environ. Sci., 2011,
4, 2721–2735.
68 J.-R. Li, Y. Ma, M. C. McCarthy, J. Sculley, J. Yu, H.-K. Jeong,
P. B. Balbuena and H.-C. Zhou, Coord. Chem. Rev., 2011, 255,
1791–1823.
69 S. Ma and H.-C. Zhou, Chem. Commun., 2010, 46, 44–53.
70 S. Ma, D. Yuan, J.-S. Chang and H.-C. Zhou, Inorg. Chem., 2009,
48, 5398–5402.
71 A. Phan, C. J. Doonan, F. J. Uribe-Romo, C. B. Knobler,
M. O’Keeffe and O. M. Yaghi, Acc. Chem. Res., 2009, 43, 58–67.
72 H. Wu, Q. Gong, D. H. Olson and J. Li, Chem. Rev., 2012, 112,
836–868.
73 K. Sumida, D. L. Rogow, J. A. Mason, T. M. McDonald,
E. D. Bloch, Z. R. Herm, T.-H. Bae and J. R. Long, Chem.
Rev., 2012, 112, 724–781.
74 O. M. Yaghi, G. Li and H. Li, Nature, 1995, 378, 703–706.
75 Q. Min Wang, D. Shen, M. Bülow, M. Ling Lau, S. Deng,
F. R. Fitch, N. O. Lemcoff and J. Semanscin, Microporous
Mesoporous Mater., 2002, 55, 217–230.
76 R. Custelcean and B. A. Moyer, Eur. J. Inorg. Chem., 2007,
1321–1340.
77 J.-R. Li, J. Sculley and H.-C. Zhou, Chem. Rev., 2012, 112,
869–932.
78 J.-R. Li, R. J. Kuppler and H.-C. Zhou, Chem. Soc. Rev., 2009,
38, 1477–1504.
79 W. Zhuang, D. Yuan, D. Liu, C. Zhong, J.-R. Li and H.-C. Zhou,
Chem. Mater., 2012, 24, 18–25.
80 Y. Liu, W. Xuan and Y. Cui, Adv. Mater., 2010, 22, 4112–4135.
81 K. A. Cychosz, R. Ahmad and A. J. Matzger, Chem. Sci., 2010, 1,
293–302.
82 S. Keskin, T. M. van Heest and D. S. Sholl, ChemSusChem, 2010,
3, 879–891.
83 M. Padmanaban, P. Muller, C. Lieder, K. Gedrich, R. Grunker,
V. Bon, I. Senkovska, S. Baumgartner, S. Opelt, S. Paasch,
E. Brunner, F. Glorius, E. Klemm and S. Kaskel, Chem. Commun.,
2011, 47, 12089–12091.
84 B. Zhao, X.-Y. Chen, P. Cheng, D.-Z. Liao, S.-P. Yan and
Z.-H. Jiang, J. Am. Chem. Soc., 2004, 126, 15394–15395.
85 B. Chen, Y. Yang, F. Zapata, G. Lin, G. Qian and
E. B. Lobkovsky, Adv. Mater., 2007, 19, 1693–1696.
86 B. Chen, L. Wang, F. Zapata, G. Qian and E. B. Lobkovsky,
J. Am. Chem. Soc., 2008, 130, 6718–6719.
87 B. V. Harbuzaru, A. Corma, F. Rey, P. Atienzar, J. L. Jordá,
H. Garcı́a, D. Ananias, L. D. Carlos and J. Rocha, Angew.
Chem., Int. Ed., 2008, 47, 1080–1083.
88 M. P. Suh, Y. E. Cheon and E. Y. Lee, Coord. Chem. Rev., 2008,
252, 1007–1026.
89 B. Chen, L. Wang, Y. Xiao, F. R. Fronczek, M. Xue, Y. Cui and
G. Qian, Angew. Chem., Int. Ed., 2009, 48, 500–503.
90 M. D. Allendorf, R. J. T. Houk, L. Andruszkiewicz, A. A. Talin,
J. Pikarsky, A. Choudhury, K. A. Gall and P. J. Hesketh, J. Am.
Chem. Soc., 2008, 130, 14404–14405.
91 L.-G. Qiu, Z.-Q. Li, Y. Wu, W. Wang, T. Xu and X. Jiang, Chem.
Commun., 2008, 3642–3644.
92 M. D. Allendorf, C. A. Bauer, R. K. Bhakta and R. J. T. Houk,
Chem. Soc. Rev., 2009, 38, 1330–1352.
93 Y. Cui, Y. Yue, G. Qian and B. Chen, Chem. Rev., 2012, 112,
1126–1162.
94 L. E. Kreno, K. Leong, O. K. Farha, M. Allendorf, R. P. Van
Duyne and J. T. Hupp, Chem. Rev., 2012, 112, 1105–1125.
95 T. Uemura, R. Kitaura, Y. Ohta, M. Nagaoka and S. Kitagawa,
Angew. Chem., Int. Ed., 2006, 45, 4112–4116.
96 C. J. Chuck, M. G. Davidson, M. D. Jones, G. Kociok-Köhn,
M. D. Lunn and S. Wu, Inorg. Chem., 2006, 45, 6595–6597.
7776
Chem. Soc. Rev., 2012, 41, 7761–7779
97 T. Uemura, D. Hiramatsu, Y. Kubota, M. Takata and S. Kitagawa,
Angew. Chem., Int. Ed., 2007, 46, 4987–4990.
98 T. Uemura, N. Yanai and S. Kitagawa, Chem. Soc. Rev., 2009,
38, 1228–1236.
99 P. Horcajada, C. Serre, M. Vallet-Regı́, M. Sebban, F. Taulelle
and G. Férey, Angew. Chem., Int. Ed., 2006, 45, 5974–5978.
100 M. Vallet-Regı́, F. Balas and D. Arcos, Angew. Chem., Int. Ed.,
2007, 46, 7548–7558.
101 P. Horcajada, C. Serre, G. Maurin, N. A. Ramsahye, F. Balas,
M. a. Vallet-Regı́, M. Sebban, F. Taulelle and G. Férey, J. Am.
Chem. Soc., 2008, 130, 6774–6780.
102 P. Horcajada, R. Gref, T. Baati, P. K. Allan, G. Maurin,
P. Couvreur, G. Férey, R. E. Morris and C. Serre, Chem. Rev.,
2012, 112, 1232–1268.
103 J. Della Rocca, D. Liu and W. Lin, Acc. Chem. Res., 2011, 44,
957–968.
104 Z. Ma and B. Moulton, Coord. Chem. Rev., 2011, 255, 1623–1641.
105 S. Keskin and S. Kızılel, Ind. Eng. Chem. Res., 2011, 50, 1799–1812.
106 A. C. McKinlay, R. E. Morris, P. Horcajada, G. Férey, R. Gref,
P. Couvreur and C. Serre, Angew. Chem., Int. Ed., 2010, 49,
6260–6266.
107 O. R. Evans and W. Lin, Acc. Chem. Res., 2002, 35, 511–522.
108 E. Y. Lee, S. Y. Jang and M. P. Suh, J. Am. Chem. Soc., 2005,
127, 6374–6381.
109 Y. Liu, G. Li, X. Li and Y. Cui, Angew. Chem., Int. Ed., 2007, 46,
6301–6304.
110 B. D. Chandler, D. T. Cramb and G. K. H. Shimizu, J. Am.
Chem. Soc., 2006, 128, 10403–10412.
111 J.-R. Li, Y. Tao, Q. Yu and X.-H. Bu, Chem. Commun., 2007,
1527–1529.
112 T.-F. Liu, J. Luü, Z. Guo, D. M. Proserpio and R. Cao, Cryst.
Growth Des., 2010, 10, 1489–1491.
113 C. Wang, T. Zhang and W. Lin, Chem. Rev., 2012, 112,
1084–1104.
114 G. J. Halder, C. J. Kepert, B. Moubaraki, K. S. Murray and
J. D. Cashion, Science, 2002, 298, 1762–1765.
115 D. Maspoch, D. Ruiz-Molina and J. Veciana, J. Mater. Chem.,
2004, 14, 2713–2723.
116 P. D. C. Dietzel, Y. Morita, R. Blom and H. Fjellvåg, Angew.
Chem., Int. Ed., 2005, 44, 6354–6358.
117 S. Horiuchi, R. Kumai and Y. Tokura, Angew. Chem., Int. Ed.,
2007, 46, 3497–3501.
118 X.-M. Zhang, Z.-M. Hao, W.-X. Zhang and X.-M. Chen, Angew.
Chem., Int. Ed., 2007, 46, 3456–3459.
119 Z. M. Wang, Y. J. Zhang, T. Liu, M. Kurmoo and S. Gao, Adv.
Funct. Mater., 2007, 17, 1523–1536.
120 M. Wriedt, S. Sellmer and C. Näther, Inorg. Chem., 2009, 48,
6896–6903.
121 S. Wöhlert, J. Boeckmann, M. Wriedt and C. Näther, Angew.
Chem., Int. Ed., 2011, 50, 6920–6923.
122 T. Okubo, R. Kawajiri, T. Mitani and T. Shimoda, J. Am. Chem.
Soc., 2005, 127, 17598–17599.
123 Q. Ye, Y.-M. Song, G.-X. Wang, K. Chen, D.-W. Fu,
P. W. Hong Chan, J.-S. Zhu, S. D. Huang and R.-G. Xiong,
J. Am. Chem. Soc., 2006, 128, 6554–6555.
124 Z. Xu, Coord. Chem. Rev., 2006, 250, 2745–2757.
125 M. Alvaro, E. Carbonell, B. Ferrer, F. X. Llabrés i Xamena and
H. Garcia, Chem.–Eur. J., 2007, 13, 5106–5112.
126 A. Kuc, A. Enyashin and G. Seifert, J. Phys. Chem. B, 2007, 111,
8179–8186.
127 J. I. Feldblyum, E. A. Keenan, A. J. Matzger and S. Maldonado,
J. Phys. Chem. C, 2012, 116, 3112–3121.
128 M. D. Allendorf, A. Schwartzberg, V. Stavila and A. A. Talin,
Chem.–Eur. J., 2011, 17, 11372–11388.
129 K. Zagorodniy, G. Seifert and H. Hermann, Appl. Phys. Lett.,
2010, 97, 251905.
130 W. Zhang and R.-G. Xiong, Chem. Rev., 2012, 112, 1163–1195.
131 R. Dawson, A. I. Cooper and D. J. Adams, Prog. Polym. Sci.,
2012, 37, 530–563.
132 H. A. Patel, F. Karadas, A. Canlier, J. Park, E. Deniz, Y. Jung,
M. Atilhan and C. T. Yavuz, J. Mater. Chem., 2012, 22,
8431–8437.
133 T. Ben, H. Ren, S. Ma, D. Cao, J. Lan, X. Jing, W. Wang, J. Xu,
F. Deng, J. M. Simmons, S. Qiu and G. Zhu, Angew. Chem., Int. Ed.,
2009, 48, 9457–9460.
This journal is
c
The Royal Society of Chemistry 2012
Downloaded by Texas A & M University on 22 February 2013
Published on 18 September 2012 on http://pubs.rsc.org | doi:10.1039/C2CS35251F
View Article Online
134 C. E. Chan-Thaw, A. Villa, P. Katekomol, D. Su, A. Thomas and
L. Prati, Nano Lett., 2010, 10, 537–541.
135 L. Chen, Y. Honsho, S. Seki and D. Jiang, J. Am. Chem. Soc.,
2010, 132, 6742–6748.
136 W. Lu, D. Yuan, D. Zhao, C. I. Schilling, O. Plietzsch, T. Muller,
S. Bräse, J. Guenther, J. Blümel, R. Krishna, Z. Li and
H.-C. Zhou, Chem. Mater., 2010, 22, 5964–5972.
137 W. Lu, D. Yuan, J. Sculley, D. Zhao, R. Krishna and
H.-C. Zhou, J. Am. Chem. Soc., 2011, 133, 18126–18129.
138 A. P. Côté, A. I. Benin, N. W. Ockwig, M. O’Keeffe,
A. J. Matzger and O. M. Yaghi, Science, 2005, 310, 1166–1170.
139 H. M. El-Kaderi, J. R. Hunt, J. L. Mendoza-Cortés, A. P. Côté,
R. E. Taylor, M. O’Keeffe and O. M. Yaghi, Science, 2007, 316,
268–272.
140 K. A. Cychosz and A. J. Matzger, Langmuir, 2010, 26, 17198–17202.
141 P. M. Schoenecker, C. G. Carson, H. Jasuja, C. J. J. Flemming
and K. S. Walton, Ind. Eng. Chem. Res., 2012, 51, 6513–6519.
142 C. D. Wood, B. Tan, A. Trewin, F. Su, M. J. Rosseinsky,
D. Bradshaw, Y. Sun, L. Zhou and A. I. Cooper, Adv. Mater.,
2008, 20, 1916–1921.
143 N. B. McKeown and P. M. Budd, Chem. Soc. Rev., 2006, 35,
675–683.
144 J.-X. Jiang, F. Su, A. Trewin, C. D. Wood, N. L. Campbell,
H. Niu, C. Dickinson, A. Y. Ganin, M. J. Rosseinsky,
Y. Z. Khimyak and A. I. Cooper, Angew. Chem., Int. Ed., 2007,
46, 8574–8578.
145 M. Rose, W. Bohlmann, M. Sabo and S. Kaskel, Chem. Commun.,
2008, 2462–2464.
146 R. Xu, W. Pang, J. Yu, Q. Huo and J. Chen, Chemistry of Zeolites
and Related Porous Materials: Synthesis and Structure, John
Wiley & Sons, Asia, Singapore, 2007.
147 S. M. Auerbach, K. A. Carrado and P. K. Dutta, Handbook of Zeolite
Science and Technology, Marcel Dekker, Inc., New York, 2003.
148 D. W. Beck, Zeolite Molecular Sieves, John Wiley & Sons,
New York, 1974.
149 P. A. Warrendale, Nanoporous and Nanostructured Materials for
Catalysis, Sensor, and Gas Separation Applications, Materials
Research Society, San Francisco, 2005.
150 J. M. Loureiro and M. T. Kartel, Combined and Hybrid Adsorbents: Fundamentals and Applications, Springer, Netherlands,
2006.
151 F. Schuth, K. S. W. Sing and J. Weitkamp, Handbook of Porous
Solids, Wiley-VCH, New York, 2002.
152 P. A. Wright, Microporous Framework Solids, RSC Publishing,
Cambridge, 2008.
153 R. A. Munson and R. A. Clifton, Natural Gas Storage with
Zeolites, U.S. Dept. of the Interior, Washington, 1971.
154 R. Babarao and J. Jiang, J. Am. Chem. Soc., 2009, 131,
11417–11425.
155 K. Berlier, M.-G. Olivier and R. Jadot, J. Chem. Eng. Data, 1995,
40, 1206–1208.
156 A. J. Kidnay and M. J. Hiza, AlChE J., 1966, 12, 58–63.
157 M. Kishima, H. Mizuhata and T. Okubo, J. Phys. Chem. B, 2006,
110, 13889–13896.
158 J.-M. Leyssale, G. K. Papadopoulos and D. N. Theodorou,
J. Phys. Chem. B, 2006, 110, 22742–22753.
159 E. Pantatosaki, F. G. Pazzona, G. Megariotis and
G. K. Papadopoulos, J. Phys. Chem. B, 2010, 114, 2493–2503.
160 O. Talu, S. Y. Zhang and D. T. Hayhurst, J. Phys. Chem., 1993,
97, 12894–12898.
161 K. L. Yeung and W. Han, in Zeolites and Catalysis, Wiley-VCH
Verlag GmbH & Co. KGaA, 2010, pp. 827–861.
162 S. Y. Zhang, O. Talu and D. T. Hayhurst, J. Phys. Chem., 1991,
95, 1722–1726.
163 J. A. F. MacDonald and D. F. Quinn, Carbon, 1996, 34,
1103–1108.
164 R. Stockmeyer, US Pat., 4,495,900, 1985.
165 L. Giraldo and J. C. Moreno-Pirajan, Adsorpt. Sci. Technol.,
2009, 27, 255–265.
166 A. Rejifu, H. Noguchi, T. Ohba, H. Kanoh, F. RodriguezReinoso and K. Kaneko, Adsorpt. Sci. Technol., 2009, 27,
877–881.
167 Y. G. Wang, C. Ercan, A. Khawajah and R. Othman, AlChE J.,
2012, 58, 782–788.
This journal is
c
The Royal Society of Chemistry 2012
168 X. D. Dai, X. M. Liu, G. Zhao, L. Qian, K. Qiao and Z. F. Yan,
Asia-Pac. J. Chem. Eng., 2008, 3, 292–297.
169 T. Y. Zhang, W. P. Walawender and L. T. Fan, Bioresour.
Technol., 2010, 101, 1983–1991.
170 D. Y. Kim, C. M. Yang, H. Noguchi, M. Yamamoto, T. Ohba,
H. Kanoh and K. Kaneko, Carbon, 2008, 46, 611–617.
171 A. A. G. Blanco, J. C. A. de Oliveira, R. Lopez, J. C. MorenoPirajan, L. Giraldo, G. Zgrablich and K. Sapag, Colloids Surf., A,
2010, 357, 74–83.
172 X. D. Dai, X. M. Liu, L. Qian, K. Qiao and Z. F. Yan, Energy
Fuels, 2008, 22, 3420–3423.
173 C. Guan, L. S. Loo, K. Wang and C. Yang, Energy Convers.
Manage., 2011, 52, 1258–1262.
174 P. K. Sahoo, M. John, B. L. Newalkar, N. V. Choudhary and
K. G. Ayappa, Ind. Eng. Chem. Res., 2011, 50, 13000–13011.
175 J. W. Lee, M. S. Balathanigaimani, H. C. Kang, W. G. Shim,
C. Kim and H. Moon, J. Chem. Eng. Data, 2007, 52, 66–70.
176 W. S. Loh, K. A. Rahman, A. Chakraborty, B. B. Saha,
Y. S. Choo, B. C. Khoo and K. C. Ng, J. Chem. Eng. Data,
2010, 55, 2840–2847.
177 K. A. Rahman, W. S. Loh, H. Yanagi, A. Chakraborty,
B. B. Saha, W. G. Chun and K. C. Ng, J. Chem. Eng. Data,
2010, 55, 4961–4967.
178 F. Rodriguez-Reinoso, C. Almansa and M. Molina-Sabio,
J. Phys. Chem. B, 2005, 109, 20227–20231.
179 M. S. Balathanigaimani, H. C. Kang, W. G. Shim, C. Kim,
J. W. Lee and H. Moon, Korean J. Chem. Eng., 2006, 23, 663–668.
180 P. Kowalczyk, H. Tanaka, K. Kaneko, A. P. Terzyk and
D. D. Do, Langmuir, 2005, 21, 5639–5646.
181 C. Solar, F. Sardella, C. Deiana, R. M. Lago, A. Vallone and
K. Sapag, Mater. Res.-Ibero-Am. J., 2008, 11, 409–414.
182 J. Alcañiz-Monge, D. Lozano-Castelló, D. Cazorla-Amorós and
A. Linares-Solano, Microporous Mesoporous Mater., 2009, 124,
110–116.
183 M. S. Balathanigaimani, W. G. Shim, J. W. Lee and H. Moon,
Microporous Mesoporous Mater., 2009, 119, 47–52.
184 M. J. Prauchner and F. Rodriguez-Reinoso, Microporous Mesoporous Mater., 2008, 109, 581–584.
185 F. Rodriguez-Reinoso, Y. Nakagawa, J. Silvestre-Albero,
J. M. Juarez-Galan and M. Molina-Sabio, Microporous Mesoporous Mater., 2008, 115, 603–608.
186 N. D. Parkyns and D. F. Quinn, in Porosity in Carbons,
ed. J. W. Patrick, Halsted Press, New York, 1995, pp. 291–325.
187 D. Lozano-Castelló, D. Cazorla-Amorós, A. Linares-Solano and
D. F. Quinn, J. Phys. Chem. B, 2002, 106, 9372–9379.
188 E. Bekyarova, K. Murata, M. Yudasaka, D. Kasuya, S. Iijima,
H. Tanaka, H. Kahoh and K. Kaneko, J. Phys. Chem. B, 2003,
107, 4681–4684.
189 J.-S. Bae and S. K. Bhatia, Energy Fuels, 2006, 20, 2599–2607.
190 C. Guan, F. Su, X. S. Zhao and K. Wang, Sep. Purif. Technol.,
2008, 64, 124–126.
191 S. Jiang, J. A. Zollweg and K. E. Gubbins, J. Phys. Chem., 1994,
98, 5709–5713.
192 J.-W. Lee, M. S. Balathanigaimani, H.-C. Kang, W.-G. Shim,
C. Kim and H. Moon, J. Chem. Eng. Data, 2006, 52, 66–70.
193 J.-W. Lee, H.-C. Kang, W.-G. Shim, C. Kim and H. Moon,
J. Chem. Eng. Data, 2006, 51, 963–967.
194 D. Lozano-Castello, D. Cazorla-Amoros, A. Linares-Solana and
D. F. Quinn, Carbon, 2002, 40, 2817–2825.
195 S. Mahdizadeh and S. Tayyari, Theor. Chem. Acc., 2011, 128,
231–240.
196 P. Pfeifer, J. W. Burress, M. B. Wood, C. M. Lapilli,
C. M. Barker, J. S. Pobst, R. J. Cepel, C. Wexler, P. S. Shah,
M. J. Gordon, G. J. Suppes, S. P. Buckley, D. J. Radke,
J. Ilavsky, A. C. Dillon, P. A. Parilla, M. Benham and
M. W. Roth, MRS Online Proc. Libr., 2007, 1041, 1041R0202.
197 D. Lozano-Castelló, D. Cazorla-Amorós and A. Linares-Solano,
Energy Fuels, 2002, 16, 1321–1328.
198 X. Shao, Z. Feng, R. Xue, C. Ma, W. Wang, X. Peng and D. Cao,
AlChE J., 2011, 57, 3042–3051.
199 H. Zhou, S. Zhu, I. Honma and K. Seki, Chem. Phys. Lett., 2004,
396, 252–255.
200 R. F. Cracknell, P. Gordon and K. E. Gubbins, J. Phys. Chem.,
1993, 97, 494–499.
Chem. Soc. Rev., 2012, 41, 7761–7779
7777
Downloaded by Texas A & M University on 22 February 2013
Published on 18 September 2012 on http://pubs.rsc.org | doi:10.1039/C2CS35251F
View Article Online
201 M. J. Bojan, R. van Slooten and W. Steele, Sep. Sci. Technol.,
1992, 27, 1837–1856.
202 S. Biloé, V. Goetz and A. Guillot, Carbon, 2002, 40, 1295–1308.
203 J. A. F. MacDonald and D. F. Quinn, Fuel, 1998, 77, 61–64.
204 J. Sun, M. J. Rood, M. Rostam-Abadi and A. A. Lizzio, Gas Sep.
Purif., 1996, 10, 91–96.
205 J. Sun, T. A. Brady, M. J. Rood, C. M. Lehmann, M. Rostam-Abadi
and A. A. Lizzio, Energy Fuels, 1997, 11, 316–322.
206 A. Celzard and V. Fierro, Energy Fuels, 2005, 19, 573–583.
207 J. A. F. MacDonald and D. F. Quinn, J. Porous Mater., 1995, 1,
43–54.
208 A. M. Rubel and J. M. Stencel, Fuel, 2000, 79, 1095–1100.
209 Y. Nakagawa, M. Molina-Sabio and F. Rodrı́guez-Reinoso,
Microporous Mesoporous Mater., 2007, 103, 29–34.
210 P. Pfeifer, L. Aston, M. Banks, S. Barker, J. Burress, S. Carter,
J. Coleman, S. Crockett, C. Faulhaber, J. Flavin, M. Gordon,
L. Hardcastle, Z. Kallenborn, M. Kemiki, C. Lapilli, J. Pobst,
R. Schott, P. Shah, S. Spellerberg, G. Suppes, D. Taylor,
A. Tekeei, C. Wexler, M. Wood, P. Buckley, T. Breier,
J. Downing, S. Eastman, P. Freeze, S. Graham, S. Grinter,
A. Howard, J. Martinez, D. Radke, T. Vassalli and J. Ilavsky,
Chaos, 2007, 17, 041108.
211 AGLARG, Report to US Dept. of Energy, Contract 466590,
1997.
212 P. Paraskeva, D. Kalderis and E. Diamadopoulos, J. Chem.
Technol. Biotechnol., 2008, 83, 581–592.
213 A. Demirbas, J. Hazard. Mater., 2009, 167, 1–9.
214 H. Wu, W. Zhou and T. Yildirim, J. Am. Chem. Soc., 2009, 131,
4995–5000.
215 G. Férey, Chem. Soc. Rev., 2008, 37, 191–214.
216 H. Deng, C. J. Doonan, H. Furukawa, R. B. Ferreira, J. Towne,
C. B. Knobler, B. Wang and O. M. Yaghi, Science, 2010, 327,
846–850.
217 Z. Wang and S. M. Cohen, Chem. Soc. Rev., 2009, 38, 1315–1329.
218 F. A. Almeida Paz, J. Klinowski, S. M. F. Vilela, J. P. C. Tome,
J. A. S. Cavaleiro and J. Rocha, Chem. Soc. Rev., 2012, 41,
1088–1110.
219 M. Servalli, M. Ranocchiari and J. A. Van Bokhoven, Chem.
Commun., 2012, 48, 1904–1906.
220 K. K. Tanabe and S. M. Cohen, Chem. Soc. Rev., 2011, 40,
498–519.
221 M. Kim, J. F. Cahill, K. A. Prather and S. M. Cohen, Chem.
Commun., 2011, 47, 7629–7631.
222 S. M. Cohen, Chem. Rev., 2012, 112, 970–1000.
223 M. Kondo, T. Yoshitomi, H. Matsuzaka, S. Kitagawa and
K. Seki, Angew. Chem., Int. Ed., 1997, 36, 1725–1727.
224 D. Y. Siberio-Pérez, A. G. Wong-Foy, O. M. Yaghi and
A. J. Matzger, Chem. Mater., 2007, 19, 3681–3685.
225 M. Dincǎ, A. Dailly, Y. Liu, C. M. Brown, D. A. Neumann and
J. R. Long, J. Am. Chem. Soc., 2006, 128, 16876–16883.
226 J. L. C. Rowsell and O. M. Yaghi, J. Am. Chem. Soc., 2006, 128,
1304–1315.
227 P. M. Forster, J. Eckert, B. D. Heiken, J. B. Parise, J. W. Yoon,
S. H. Jhung, J.-S. Chang and A. K. Cheetham, J. Am. Chem. Soc.,
2006, 128, 16846–16850.
228 N. Guillou, Q. Gao, P. M. Forster, J.-S. Chang, M. Noguès,
S.-E. Park, G. Férey and A. K. Cheetham, Angew. Chem., Int.
Ed., 2001, 40, 2831–2834.
229 Y. Liu, H. Kabbour, C. M. Brown, D. A. Neumann and
C. C. Ahn, Langmuir, 2008, 24, 4772–4777.
230 J. G. Vitillo, L. Regli, S. Chavan, G. Ricchiardi, G. Spoto,
P. D. C. Dietzel, S. Bordiga and A. Zecchina, J. Am. Chem.
Soc., 2008, 130, 8386–8396.
231 N. L. Rosi, J. Kim, M. Eddaoudi, B. Chen, M. O’Keeffe and
O. M. Yaghi, J. Am. Chem. Soc., 2005, 127, 1504–1518.
232 H. Wu, J. M. Simmons, Y. Liu, C. M. Brown, X.-S. Wang, S. Ma,
V. K. Peterson, P. D. Southon, C. J. Kepert, H.-C. Zhou,
T. Yildirim and W. Zhou, Chem.–Eur. J., 2010, 16, 5205–5214.
233 S. Ma, X.-S. Wang, C. D. Collier, E. S. Manis and H.-C. Zhou,
Inorg. Chem., 2007, 46, 8499–8501.
234 D. Zhao, D. Yuan, A. Yakovenko and H.-C. Zhou, Chem.
Commun., 2010, 46, 4196–4198.
235 C. E. Wilmer, M. Leaf, C. Y. Lee, O. K. Farha, B. G. Hauser,
J. T. Hupp and R. Q. Snurr, Nat. Chem., 2012, 4, 83–89.
7778
Chem. Soc. Rev., 2012, 41, 7761–7779
236 S. M. P. Lucena, P. G. M. Mileo, P. F. G. Silvino and
C. L. Cavalcante, J. Am. Chem. Soc., 2011, 133, 19282–19285.
237 J. R. Karra and K. S. Walton, Langmuir, 2008, 24, 8620–8626.
238 Z. Guo, H. Wu, G. Srinivas, Y. Zhou, S. Xiang, Z. Chen,
Y. Yang, W. Zhou, M. O’Keeffe and B. Chen, Angew. Chem.,
Int. Ed., 2011, 50, 3178–3181.
239 W. Zhou, H. Wu and T. Yildirim, J. Am. Chem. Soc., 2008, 130,
15268–15269.
240 H. K. Chae, D. Y. Siberio-Perez, J. Kim, Y. Go, M. Eddaoudi,
A. J. Matzger, M. O’Keeffe and O. M. Yaghi, Nature, 2004, 427,
523–527.
241 K. S. Walton and R. Q. Snurr, J. Am. Chem. Soc., 2007, 129,
8552–8556.
242 S. S. Han and W. A. Goddard, J. Phys. Chem. C, 2008, 112,
13431–13436.
243 D. Zhao, D. Yuan, D. Sun and H.-C. Zhou, J. Am. Chem. Soc.,
2009, 131, 9186–9188.
244 M. Eddaoudi, J. Kim, J. B. Wachter, H. K. Chae, M. O’Keeffe
and O. M. Yaghi, J. Am. Chem. Soc., 2001, 123, 4368–4369.
245 H. Abourahma, A. W. Coleman, B. Moulton, B. Rather,
P. Shahgaldian and M. J. Zaworotko, Chem. Commun., 2001,
2380–2381.
246 B. Moulton, J. Lu, A. Mondal and M. J. Zaworotko, Chem.
Commun., 2001, 863–864.
247 Y. Ke, D. J. Collins and H.-C. Zhou, Inorg. Chem., 2005, 44,
4154–4156.
248 H. Furukawa, J. Kim, K. E. Plass and O. M. Yaghi, J. Am. Chem.
Soc., 2006, 128, 8398–8399.
249 Y. Yan, S. Yang, A. J. Blake, W. Lewis, E. Poirier, S. A. Barnett,
N. R. Champness and M. Schroder, Chem. Commun., 2011, 47,
9995–9997.
250 C. Tan, S. Yang, N. R. Champness, X. Lin, A. J. Blake, W. Lewis
and M. Schroder, Chem. Commun., 2011, 47, 4487–4489.
251 H. Furukawa, N. Ko, Y. B. Go, N. Aratani, S. B. Choi, E. Choi,
A. Ö. Yazaydin, R. Q. Snurr, M. O’Keeffe, J. Kim and
O. M. Yaghi, Science, 2010, 329, 424–428.
252 S. S. Han, H. Furukawa, O. M. Yaghi and W. A. Goddard,
J. Am. Chem. Soc., 2008, 130, 11580–11581.
253 H. Furukawa and O. M. Yaghi, J. Am. Chem. Soc., 2009, 131,
8875–8883.
254 R. W. Tilford, S. J. Mugavero, P. J. Pellechia and J. J. Lavigne,
Adv. Mater., 2008, 20, 2741–2746.
255 A. P. Côté, H. M. El-Kaderi, H. Furukawa, J. R. Hunt and
O. M. Yaghi, J. Am. Chem. Soc., 2007, 129, 12914–12915.
256 Y. Du, K. Mao, P. Kamakoti, P. Ravikovitch, C. Paur, S. Cundy,
Q. Li and D. Calabro, Chem. Commun., 2012, 48, 4606–4608.
257 L. M. Lanni, R. W. Tilford, M. Bharathy and J. J. Lavigne,
J. Am. Chem. Soc., 2011, 133, 13975–13983.
258 J. L. Mendoza-Cortes, S. S. Han, H. Furukawa, O. M. Yaghi and
W. A. Goddard, J. Phys. Chem. A, 2010, 114, 10824–10833.
259 J. L. Mendoza-Cortes, T. A. Pascal and W. A. Goddard, J. Phys.
Chem. A, 2011, 115, 13852–13857.
260 J. Lan, D. Cao and W. Wang, Langmuir, 2009, 26, 220–226.
261 S. K. Bhatia and A. L. Myers, Langmuir, 2006, 22, 1688–1700.
262 Q. Ye, S. Yan, D. Liu, Q. Yang and C. Zhong, Mol. Simul., 2010,
36, 682–692.
263 S. Wang, Energy Fuels, 2007, 21, 953–956.
264 X.-S. Wang, S. Ma, P. M. Forster, D. Yuan, J. Eckert,
J. J. López, B. J. Murphy, J. B. Parise and H.-C. Zhou, Angew.
Chem., Int. Ed., 2008, 47, 7263–7266.
265 T. L. Cook, C. Komodromos, D. F. Quinn and S. Ragan, in
Carbon Materials for Advanced Technologies, ed. T. D. Burchell,
Pergamon, Amsterdam, New York, 1999.
266 R. Getman, Atlanta Gas Light Co. R&D Report #91, 1991.
267 R. N. Fricker and N. D. Parkyns, Adsorbed Natural Gas Road
Vehicle NGV’92, Gothenberg, Sweden, 1992.
268 M. Kondo, T. Okubo, A. Asami, S.-i. Noro, T. Yoshitomi,
S. Kitagawa, T. Ishii, H. Matsuzaka and K. Seki, Angew. Chem.,
Int. Ed., 1999, 38, 140–143.
269 S.-i. Noro, S. Kitagawa, M. Kondo and K. Seki, Angew. Chem.,
Int. Ed., 2000, 39, 2081–2084.
270 W. Zhou, H. Wu, M. R. Hartman and T. Yildirim, J. Phys.
Chem. C, 2007, 111, 16131–16137.
271 R. Babarao and J. Jiang, Langmuir, 2008, 24, 5474–5484.
This journal is
c
The Royal Society of Chemistry 2012
Downloaded by Texas A & M University on 22 February 2013
Published on 18 September 2012 on http://pubs.rsc.org | doi:10.1039/C2CS35251F
View Article Online
272 S. Bourrelly, P. L. Llewellyn, C. Serre, F. Millange, T. Loiseau
and G. Férey, J. Am. Chem. Soc., 2005, 127, 13519–13521.
273 P. L. Llewellyn, S. Bourrelly, C. Serre, A. Vimont, M. Daturi,
L. Hamon, G. De Weireld, J.-S. Chang, D.-Y. Hong, Y. Kyu
Hwang, S. Hwa Jhung and G. Ferey, Langmuir, 2008, 24,
7245–7250.
274 I. Senkovska and S. Kaskel, Microporous Mesoporous Mater.,
2008, 112, 108–115.
275 S. Surblé, F. Millange, C. Serre, T. Düren, M. Latroche,
S. Bourrelly, P. L. Llewellyn and G. Férey, J. Am. Chem. Soc.,
2006, 128, 14889–14896.
276 C. Volkringer, T. Loiseau, M. Haouas, F. Taulelle, D. Popov,
M. Burghammer, C. Riekel, C. Zlotea, F. Cuevas, M. Latroche,
D. Phanon, C. Knöfelv, P. L. Llewellyn and G. Ferey, Chem.
Mater., 2009, 21, 5783–5791.
277 X.-S. Wang, S. Ma, K. Rauch, J. M. Simmons, D. Yuan,
X. Wang, T. Yildirim, W. C. Cole, J. J. López, A. d. Meijere
and H.-C. Zhou, Chem. Mater., 2008, 20, 3145–3152.
278 P. D. C. Dietzel, V. Besikiotis and R. Blom, J. Mater. Chem.,
2009, 19, 7362–7370.
279 P. Kanoo, K. L. Gurunatha and T. K. Maji, J. Mater. Chem.,
2010, 20, 1322–1331.
280 Y. Hu, S. Xiang, W. Zhang, Z. Zhang, L. Wang, J. Bai and
B. Chen, Chem. Commun., 2009, 7551–7553.
281 M. Kondo, M. Shimamura, S.-i. Noro, S. Minakoshi, A. Asami,
K. Seki and S. Kitagawa, Chem. Mater., 2000, 12, 1288–1299.
282 B. Mu, F. Li and K. S. Walton, Chem. Commun., 2009, 2493–2495.
283 D.-W. Jung, D.-A. Yang, J. Kim, J. Kim and W.-S. Ahn, Dalton
Trans., 2010, 39, 2883–2887.
284 D. Saha, Z. Bao, F. Jia and S. Deng, Environ. Sci. Technol., 2010,
44, 1820–1826.
285 M. Anbia, V. Hoseini and S. Sheykhi, J. Ind. Eng. Chem., 2012,
18, 1149–1152.
286 B. Chen, C. Liang, J. Yang, D. S. Contreras, Y. L. Clancy,
E. B. Lobkovsky, O. M. Yaghi and S. Dai, Angew. Chem., Int.
Ed., 2006, 45, 1390–1393.
287 L. Bastin, P. S. Barcia, E. J. Hurtado, J. A. C. Silva,
A. E. Rodrigues and B. Chen, J. Phys. Chem. C, 2008, 112,
1575–1581.
288 B. Mu, P. M. Schoenecker and K. S. Walton, J. Phys. Chem. C,
2010, 114, 6464–6471.
289 C. A. Fernandez, P. K. Thallapally, R. K. Motkuri, S. K. Nune,
J. C. Sumrak, J. Tian and J. Liu, Cryst. Growth Des., 2010, 10,
1037–1039.
290 H. J. Park and M. P. Suh, Chem. Commun., 2010, 46, 610–612.
This journal is
c
The Royal Society of Chemistry 2012
291 Y. E. Cheon, J. Park and M. P. Suh, Chem. Commun., 2009,
5436–5438.
292 S. K. Nune, P. K. Thallapally, A. Dohnalkova, C. Wang, J. Liu
and G. J. Exarhos, Chem. Commun., 2010, 46, 4878–4880.
293 H. Hayashi, A. P. Côté, H. Furukawa, M. O’Keeffe and
O. M. Yaghi, Nat. Mater., 2007, 6, 501–506.
294 R. Banerjee, H. Furukawa, D. Britt, C. Knobler, M. O’Keeffe and
O. M. Yaghi, J. Am. Chem. Soc., 2009, 131, 3875–3877.
295 Y.-S. Bae, O. K. Farha, J. T. Hupp and R. Q. Snurr, J. Mater.
Chem., 2009, 19, 2131–2134.
296 M. Xue, Y. Liu, R. M. Schaffino, S. Xiang, X. Zhao, G.-S. Zhu,
S.-L. Qiu and B. Chen, Inorg. Chem., 2009, 48, 4649–4651.
297 E. Neofotistou, C. D. Malliakas and P. N. Trikalitis, Chem.–Eur. J.,
2009, 15, 4523–4527.
298 Y.-S. Bae, K. L. Mulfort, H. Frost, P. Ryan, S. Punnathanam,
L. J. Broadbelt, J. T. Hupp and R. Q. Snurr, Langmuir, 2008, 24,
8592–8598.
299 J. W. Yoon, S. H. Jhung, Y. K. Hwang, S. M. Humphrey,
P. T. Wood and J. S. Chang, Adv. Mater., 2007, 19, 1830–1834.
300 Y.-S. Bae, O. K. Farha, A. M. Spokoyny, C. A. Mirkin,
J. T. Hupp and R. Q. Snurr, Chem. Commun., 2008, 4135–4137.
301 O. K. Farha, A. M. Spokoyny, K. L. Mulfort, M. F. Hawthorne,
C. A. Mirkin and J. T. Hupp, J. Am. Chem. Soc., 2007, 129,
12680–12681.
302 S. Cavenati, C. A. Grande, A. r. E. Rodrigues, C. Kiener and
U. Muüller, Ind. Eng. Chem. Res., 2008, 47, 6333–6335.
303 H. R. Moon, N. Kobayashi and M. P. Suh, Inorg. Chem., 2006,
45, 8672–8676.
304 S.-M. Zhang, Z. Chang, T.-L. Hu and X.-H. Bu, Inorg. Chem.,
2010, 49, 11581–11586.
305 E. Barea, G. Tagliabue, W.-G. Wang, M. Pérez-Mendoza,
L. Mendez-Liñan, F. J. López-Garzon, S. Galli, N. Masciocchi
and J. A. R. Navarro, Chem.–Eur. J., 2010, 16, 931–937.
306 Z. Chen, S. Xiang, H. D. Arman, P. Li, S. Tidrow, D. Zhao and
B. Chen, Eur. J. Inorg. Chem., 2010, 2010, 3745–3749.
307 Z. Zhang, S. Xiang, Y.-S. Chen, S. Ma, Y. Lee, T. Phely-Bobin
and B. Chen, Inorg. Chem., 2010, 49, 8444–8448.
308 Z. Zhang, S. Xiang, X. Rao, Q. Zheng, F. R. Fronczek, G. Qian
and B. Chen, Chem. Commun., 2010, 46, 7205–7207.
309 H. Li, W. Shi, K. Zhao, Z. Niu, X. Chen and P. Cheng,
Chem.–Eur. J., 2012, 18, 5715–5723.
310 H. R. Abid, G. H. Pham, H.-M. Ang, M. O. Tade and S. Wang,
J. Colloid Interface Sci., 2012, 366, 120–124.
311 C. Li, W. Qiu, W. Shi, H. Song, G. Bai, H. He, J. Li and
M. J. Zaworotko, CrystEngComm, 2012, 14, 1929–1932.
Chem. Soc. Rev., 2012, 41, 7761–7779
7779