Development and Evaluation of Zeolites and Metal–Organic Frameworks for Carbon Dioxide Separation and Capture

Abstract

With increasing carbon dioxide (CO2) emissions from the combustion of fossil-based fuels, the concentration of CO2 in the atmosphere is growing at 407.54[1] parts per million, as released in May 2016. Accordingly, the reduction of CO2 emissions is an essential issue for global climate changes. Tremendous efforts have been directed towards the goal of CO2 separation and capture. These have led to the development of novel classes of porous materials that possess unique potential applications in the capture and sequestration of CO2.
Hence, this comprehensive review focuses on studying and analyzing newly developed methods to reduce greenhouse gas emissions and to sequester CO2 released from anthropogenic activities. It compares and analyzes, in terms of storage capacity and adsorption selectivity, the innovative technologies that capture CO2. Also described are the key advancements in CO2 capture from chemical absorption post- and precombustion industrial units and its subsequent physical adsorption by using various zeolites and metal–organic framework (MOF) materials for CO2 adsorption, storage, and separation. Current progress in MOF materials for CO2 capture is considered, and the potentials and limitations of new discoveries in the area are addressed, as it is a rapidly growing area. Furthermore, trends in the design of various kinds of porous structures with tailored macro- and microstructures and target surface properties are examined

Full text

DOI: 10.1002/ente.201600359
Development and Evaluation of Zeolites and Metal–
Organic Frameworks for Carbon Dioxide Separation and
Capture
Mustafa Abu Ghalia and Yaser Dahman*[a]
1. Overview and Background
The capture of CO2is motivated by the forecasted alteration
in the global climate, which has resulted from the worlds re-
liance on fossil fuels for energy generation. Controlling CO2
emissions to stabilize global warming is an essential chal-
lenge for the future. Various separation technologies such as
chemical absorption, adsorption, cryogenics, membranes, and
microbial/algal systems can be applied to capture CO2from
gas mixtures, and these are commercial activities that occur
in hydrogen, ammonia, and natural gas purification plants.
Nevertheless, chemical absorption and adsorption are cur-
rently believed to be the most appropriate methods for post-
combustion power plants.[2] Typically, CO2is vented to the at-
mosphere, and in some cases, it is captured and reused. The
present primary applications of CO2include enhanced oil re-
covery (EOR) and the carbonated beverages industry.[3] The
conventional method for CO2capture for this technique is
through solvent-based absorption. It is still unclear whether
this technology will be the optimal method to tackle the
amount of CO2released on an annual basis ( 30 Gt world-
wide).[4] The current technologies of synthesized gas mixtures
that consist of CO2from power plants have led to a dramatic
expansion of research developments and several concepts re-
lated to clean energy conversion processes. The principle of
thermodynamic laws sets boundaries on the minimum work
required for CO2separation. Actual separation processes
will come with irreversibility, which will result in inefficien-
cies.[5] Factors affecting these efficiencies depend on the op-
erational conditions, maintenance, and capital costs. Gas stor-
age in porous solids such as activated carbons, zeolites,
porous coordination polymers (PCPs), and metal–organic
frameworks (MOFs) has become a very attractive option for
various environmental applications.[6–8] For a provided set of
pressure, volume, and temperature parameters for the unit
operations, specifically at low to moderate pressures, more
gas can be stored in adsorbent-filled tanks rather than under
uncontrolled conditions. In this method, the efficient storage
of CO2for overall use remains an elusive topic.[9] Several ex-
amples available in the literature are restricted to long-term
storage for environmental applications as a target for re-
duced carbon emissions and short-term storage for which re-
covery of the gas is necessary for a subsequent process. This
includes CO2reduction for resource recovery in portable
closed-volume settings, such as submarines or spaceships.[10]
For these particular applications, the adsorption-based stor-
age of CO2presents safety and economic advantages, as both
high pressures and high energy inputs can be avoided while
retaining a maximum storage capacity. Adsorbents that ex-
hibit steep, linear, and reversible isotherms are desirable, as
a small variation in pressure produces a relatively high un-
loading of CO2.[11] Hence, adsorption reversibility and total
delivery capacity under nonequilibrium conditions should be
With increasing carbon dioxide (CO2) emissions from the
combustion of fossil-based fuels, the concentration of CO2in
the atmosphere is growing at 407.54[1] parts per million, as re-
leased in May 2016. Accordingly, the reduction of CO2emis-
sions is an essential issue for global climate changes. Tremen-
dous efforts have been directed towards the goal of CO2sep-
aration and capture. These have led to the development of
novel classes of porous materials that possess unique poten-
tial applications in the capture and sequestration of CO2.
Hence, this comprehensive review focuses on studying and
analyzing newly developed methods to reduce greenhouse
gas emissions and to sequester CO2released from anthropo-
genic activities. It compares and analyzes, in terms of storage
capacity and adsorption selectivity, the innovative technolo-
gies that capture CO2. Also described are the key advance-
ments in CO2capture from chemical absorption post- and
precombustion industrial units and its subsequent physical
adsorption by using various zeolites and metal–organic
framework (MOF) materials for CO2adsorption, storage,
and separation. Current progress in MOF materials for CO2
capture is considered, and the potentials and limitations of
new discoveries in the area are addressed, as it is a rapidly
growing area. Furthermore, trends in the design of various
kinds of porous structures with tailored macro- and micro-
structures and target surface properties are examined.
[a] M. Abu Ghalia, Prof. Y. Dahman
Department of Chemical Engineering
Ryerson University
Toronto, Ontario M5B 2K3 (Canada)
E-mail: ydahman@ryerson.ca
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
1
&
These are not the final page numbers! ÞÞ

key factors to study upon considering a material for storage
applications. Although adsorption may display a maximum
loading capacity at a certain pressure, this phenomenon does
not describe the available amount or actual unloading ca-
pacity of CO2upon delivery.[12]
The detrimental effects of increasing CO2levels on global
climate have been well defined, and it is clear that there is
a demand to reduce CO2emissions into the atmosphere. Sev-
eral studies based on observations have revealed that the in-
creasing global average air and ocean temperatures affect
the global average sea levels. In addition, the widespread
melting of sea ice has demonstrated that climate change is
clearly linked to both human activity and natural climate
change.[13–15] In general, several approaches can be adopted
to reduce the total amount of CO2emitted into the atmos-
phere, which include reducing energy consumption by im-
proving efficiency, reducing carbon emissions by using re-
newable energy sources, and enhancing separations of CO2
through the development of new porous capture technolo-
gies. Furthermore, the use of nonfossil fuels, for instance, hy-
drogen, biomass, and solar energy, as alternative sources pro-
vides cleaner sources of energy that have a much lower envi-
ronmental impact than conventional energy technologies. A
schematic flow diagram (Figure 1) illustrates CO2capture by
chemical absorption and adsorption. The adsorptions are
subdivided into physical adsorption and chemical adsorption.
Amine-based absorbents can be classified as amine-impreg-
nated materials or amine-grafted materials through weak in-
teractions or strong covalent bonding.[16,17] Amine-grafted ad-
sorbents exhibit higher adsorption rates and higher stabilities
than amine-impregnated adsorbents, but the amount of
amine grafted is lower than the amount of amine impregnat-
ed, as determined by the number of surface silane groups.
Nonetheless, a higher amine content is obtained by impreg-
nation. Moreover, basic organic groups (e.g., amines) and in-
organic metal oxides (e.g., alkali metals such as lithium or
alkali-earth metals such as calcium) enhance interactions be-
tween the acidic CO2molecules and the modified basic
active sites on the surface through the formation of covalent
bonds.[18] Consequently, this article highlights the latest ad-
vances in the design of porous materials, including chemical-
absorption-based amines for CO2capture in applications of
postcombustion power plants and regeneration processes re-
garding energy consumption. The second part of the article is
dedicated to reviewing recent advances in CO2separation by
using microcrystalline porous solids and MOFs. The current
state in the field of porous materials dictates that the evalua-
tion and performance of CO2adsorption will be determined
according to benchmark criteria. Thus, the most appropriate
material should be achieved in a timely manner, which there-
by would accelerate its deployment on an industrial scale.
We believe that the field of porous materials is of substantial
interest in gas separation and catalysis and for the develop-
ment of several applications ranging from the potential
design of sustainable technologies to reducing and control-
ling CO2emissions.
2. CO2Capture Technologies and Electrostatic
Properties
The CO2capturing technologies of combustion reactions are
divided into three stages (postcombustion, precombustion,
and oxyfuel). CO2capture in postcombustion is separated
from the flue gas after burning fossil fuels or biomass in the
presence of air. The main outputs of this combustion reac-
tion include N2,O
2, and CO2. Presently, postcombustion pro-
cesses are among the most used in CO2capture from station-
ary sources (Figure 2). The precombustion process is divided
into three stages. First, the fuel conversion (coal or biomass)
is gasified, that is, it is converted into carbon monoxide (CO)
and hydrogen (H2); this mixture is called syngas. Second,
steam reforming converts CO into CO2in the presence of ex-
isting air to yield more hydrogen. Third and last, CO2is sepa-
Mustafa Abu Ghalia received his B.Sc.
degree from Tripoli University in 2000.
He worked as a research scientist at the
Center for Macromolecular Chemistry
and Technology, Libya-Tripoli, for
10 years. He conducted active research in
the area of polymer processing and tech-
nology (synthesis, developments, and
characterization) and obtained his
M.Eng. degree (Polymer of Engineering)
from the University Technology, Malaysia,
in 2011. He is currently a Ph.D. candi-
date and research assistant working under the guidance of Prof. Yaser
Dahman in the Department of Chemical Engineering at Ryerson Uni-
versity, Toronto. His current research interest focuses on several emerg-
ing areas of technology in the fields of green biodegradable polymers
and nanotechnology, with a particular interest in biomedical engineer-
ing. In addition, he is actively involved in developing and testing new
types of polymeric biomaterials.
Yaser Dahman is a faculty member in the
Department of Chemical Engineering at
Ryerson University, Toronto, Canada,
where he is Director of the Green Re-
search Technology Center. His academic
credentials include a Ph.D. degree in
Chemical and Biochemical Engineering
and an MBA. Prof. Dahman has commis-
sioned several research projects and pro-
grams in the emerging field of green tech-
nology. His research activities are mainly
focused on utilizing green processes and
reactions that are cost competitive and environmentally friendly to pro-
duce green biomaterials in addition to green biofuels. In his research ap-
proach, he utilizes renewable and sustainable resources of biomass (ag-
roindustrial wastes and algae) in simultaneous saccharification and fer-
mentation and separate hydrolysis and fermentation to produce green
biomaterials, green biodegradable plastics, and green biobutanol and bi-
oethanol.
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VC H Verlag GmbH & Co. KGaA, Weinheim
&
2
&
These are not the final page numbers! ÞÞ

rated from hydrogen. The final product of the latter can be
used in several applications such as energy generation or
fuels. In oxygen combustion (or oxycombustion technology),
natural gases and coal are reacted with pure oxygen. In this
method, CO2is produced (in high concentration >80 %),
which results in a flue gas that is mainly CO2and H2O vapor,
and these can be easily separated by air separation. A critical
part of this technology is the previous requirement for
oxygen separation from air, which is usually performed
through a cryogenic process.[19,20] Figure 2 summarizes the
different types of combustion reactions (e.g., energy, fuel,
and air separation) that produce CO2in their output reac-
tions. Once CO2is captured, it is compressed to a high densi-
ty. The storage method includes injecting CO2into under-
ground geological formations, and the industrial processes
also utilize and store a small amount of CO2for other manu-
factured products.
One of the most important factors for gas-separation ma-
terials is that the differences in the kinetic properties of the
gases are small. The kinetic diameter is an indicator of the
lowest effective dimensions of a particular molecule. Never-
theless, differences exist in the electronic properties of the
gases, such as the quadrupolar moment and polarization.
CO2gas has a large quadrupole moment (13.4  1040 Cm
2vs.
4.7 1040 Cm
2for N2,CH
4is nonpolar), and CH4adsorbs
preferentially over N2owing to its higher polarizability
(26.3 1025 cm3for CO2vs. 17.6  1025 cm3for N2and 26.0
1025 cm3for CH4).[21] It is clear that the quadrupole moment
of CO2is greater than those of most other gases. This is
useful for high selectivity related to the separation of CO2
from N2and CH4by using zeolite and MOF adsorptions.
These parameters can be used as selective criteria for separa-
tion by adsorption or diffusion throughout a bed of sorbent
particles.
3. Chemisorption Technologies: Amine-Based Ad-
sorbents
Chemisorption is a kind of adsorption that involves chemical
bonds between the adsorbate molecule and a specific surface.
Scrubbing technologies are typical examples for CO2capture
that have been used in the industry for over 50 years, and
they are based substantially on the industrially essential pri-
Figure 2. Postcombustion, precombustion, and oxyfuel combustion processes.[21]
Figure 1. Flow diagram for CO2capture by absorption and adsorption.[16]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VC H Verlag GmbH & Co. KGaA, Weinheim
&
3
&
These are not the final page numbers! ÞÞ

mary alkanol amine -aminoethanol (MEA). The process in-
cludes the passage of an aqueous amine solution (typically
25–30 wt%) down the top of an absorption tower. In the
meantime, a gaseous stream of flue gas containing CO2is en-
tered at the bottom. The blower is required to pump the gas
through the absorber at a temperature of approximately
408C. The reaction between CO2and the amine occurs
through a zwitterionic mechanism and affords carbamates;
a reaction mechanism is described in Scheme 1a.[22] The
liquid amine CO2-rich solvent passes through the packing,
and consequently, the gas–liquid contact area and the mass-
transfer rates are increased.
The normal operation conditions for the CO2adsorption
process involve relatively high temperatures (100–140 8C)
and atmospheric pressure. The high heat of formation related
to carbamate production leads to a considerable energy pen-
alty for regeneration of the solvent and subsequent regenera-
tion the amine solution. The amine solution is cycled back
into the absorption tower for additional CO2absorption.[23, 24]
As presented in Scheme 1a, the CO2loading capacity for pri-
mary and secondary amines is set in the range of 0.5 to
1 mole of CO2per mole of amine. A fraction of the carba-
mate species is hydrolyzed to form hydrogen carbonates. The
reaction between CO2and tertiary amines, such as N-methyl-
diethanolamine (MDEA), occurs with a higher loading ca-
pacity of 1 mole of CO2per mole of amine, with a lower re-
activity towards CO2relative to that of primary amines. The
carbonation reaction (Scheme 1 a) cannot proceed for terti-
ary amines unless a base-catalyzed hydration of CO2is used
to form hydrogen carbonate (Scheme 1b).[25] MDEA is com-
monly employed for natural gas treatment, and it exhibits
lower solvent degradation rates in addition to a low energy
penalty for the regeneration of the solvent in the stripper. In
particular, the addition of small quantities of primary and
secondary amines enhances the CO2absorption rates for ter-
tiary amines. Specialty amines, such as hindered amines, have
been formulated to overcome some of the limitations of con-
ventional primary, secondary, and tertiary amines.[26,27] Sever-
al reports on the thermodynamic capacities and absorption/
desorption rates of CO2–amine reactions have elucidated
that steric hindrance and the basicity of the amine are signifi-
cant factors that control the efficiency of CO2capture reac-
tions. Sterically hindered amines such as 2-amino-2-methyl-1-
propanol (AMP) that contain bulkier substituents have been
confirmed as the most effective absorption solvents because
of the lower stability of their carbamates [carbamate stability
constant at 303 K for AMP is 0.1, for 2,2’-iminodiethanol
(DEA) it is 2.0, and for MEA it is 12.5].[28] The concept is
that hindered amines depend on the rates of the reactions of
acid gases with different amine molecules. The capacity of
the solvent can be improved to remove CO2if one of the in-
termediate reactions, that is, the carbamate formation reac-
tion, can be decelerated by providing steric hindrance to the
reacting CO2. The mechanism of these steps is represented in
Scheme 1 and permit CO2loadings in the excess of 0.5 mol
equivalents to be attained with regeneration rates that are
higher than those of traditional alkanol amines (e.g., the CO2
regeneration rate ratio for AMP/MEA is 1.83). Differences
in the absorption rates of hindered amines have also been
observed; for instance, 2-piperidineethanol exhibits better
performance than AMP and conventional alkanol amines
owing to the lower stability of its carbamate and the higher
rate constant for its reaction with CO2. Inorganic solvents,
such as aqueous potassium and sodium carbonate as well as
aqueous ammonia solutions have also been considered for
chemical absorption. The chilled ammonia process for CO2
capture includes the reversible formation of ammonium hy-
drogen carbonate with forward reaction to capture CO2as
a solid in NH4HCO3, which occurs at a temperature of
208C.[29]
4. Physisorption Technologies: Optimized Zeolites
Physisorption processes are principally associated with van
der Waals forces. Correspondingly, they are also known as
dispersion–repulsion forces and electrostatic forces, which
are obtained from polarization, dipole, quadrupole, and
higher pole interactions.[30] van der Waals forces are present
in all systems. Nonetheless, electrostatic interactions are only
present in systems that contain charges, such as zeolites,
MOFs, and sorbents with surface functional groups and sur-
face defects. One of the most interesting porous materials
used in CO2capture are zeolites, which exhibit high adsorp-
tion capacities with thermal stabilities reaching up to 600 8C
owing to their unique chemical properties and structure;
they form the basis for applications in gases separation, ion-
exchange beds, and catalysis. 31,32] In addition, new applica-
tions of zeolite materials have been created in electricity, lu-
minescence, magnetism, medicine, and microelectronics. The
wide range of zeolite applications is a consequence of their
unique porous structures and specific chemical composi-
tions.[33] The synthesis of new zeolite structures is based on
Scheme 1. General reaction schemes for the chemical absorption of CO2by
a) primary or secondary amine-containing solvents and b) tertiary amine-con-
taining solvents.[22]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VC H Verlag GmbH & Co. KGaA, Weinheim
&
4
&
These are not the final page numbers! ÞÞ

three main synthetic strategies: heteroatom substitution, top-
otactic transformation, and predesigned structure-directing
agents (SDAs). The using of predesigned organic SDAs
allows the synthesis of new classes of zeolites with hierarchi-
cal pores, an odd number of rings, extremely complex frame-
work topologies, and extralarge pores. These synthesized
zeolites can be tailored by varying the size, shape, charge, ri-
gidity, hydrophobicity, and polarity of the organic SDAs.
Hence, the rational design of organic SDAs is a useful ap-
proach for the synthesis of novel zeolite structures, including
proton sponges, P-containing SDAs, imidazolium derivatives,
and metal complexes; these SDAs can be used to direct the
synthesis of extralarge pore or chiral zeolite structures, be-
cause of their special design and rigid conformations.[34] The
use of SDAs allows the discovery of many new zeolites with
unprecedented structural features, including hierarchical
pores, odd number of rings (11–15-rings), extralarge pores
(16, 18, 20, 28, and 30 rings), chiral pores, and very complex
framework topologies predesigned by the structure-directing
agents. Table 1 illustrates the highest selectivity equilibrium
for CO2/N2from other different zeolite materials. The results
demonstrate that zeolite CaL shows remarkably higher CO2/
N2selectivity than other zeolites. This zeolite can be used at
atmospheric pressure, which indicates that the CaL zeolite is
a better absorbent candidate for the separation of CO2and
N2owing to is relatively high surface area (462 m2g1).[35]
Furthermore, novel classes of zeolites with channel openings
that are eight-ring pores, such as copper aluminosilicate zeo-
lite (Cu-SSZ-13), silico–aluminophosphates (SAPO-56), and
silicoaluminophosphate with an RHO framework (SAPO-
RHO), show high adsorption capacities in the separation of
CO2and N2(33.1, 42, and 84, respectively).[41–43]
4.1. Structural characteristics of zeolites for CO2adsorption
There are several aspects that affect the CO2adsorption ca-
pacity of zeolites, and they include cation exchange, surface
area, porosity, pore size, and chemical composition in addi-
tion to the stability of the structure and heat adsorption in
the zeolites. Study of the properties of a CO2adsorbent and
the relationship between the physisorption properties associ-
ated with the capacity of the chemisorption stability are nec-
essary upon designing zeolites as CO2sorbents. Thus, this
section predominantly emphases the structures obtained
under various conditions for a better understanding and com-
parison with other gases.
4.1.1. CO2adsorption on zeolites: framework topology and com-
position
Potential adsorbents for CO2separation from gases mixtures
are highly selective towards zeolites that possess different
topologies, chemical compositions (Si/Al ratio and extra-
framework cations), and designable pore structures. The
siting and distribution of the framework Al atoms in Si-rich
zeolites are important zeolite factors that should also be in-
cluded in the evaluation and analysis of the structure, proper-
ties, and activity of the counterion species. The largest heter-
ogeneity of the CO2adsorption sites can be found in zeolites
with intermediate Si/Al ratios. The same set of SC (straight
channel) sites as those created in high-silica materials are
also available in the intersection and channel wall sites dif-
fering in metal cation/framework coordination, whereas in
the case of CO2adsorption on Na-Y, no CO2adsorption
complexes on dualcation site (DC sites) are found.[44] This
observation is explained by the fact that the Na+cations in
adjacent SII sites (inside the zeolite supercage) are 9.9 
apart from each other, which is a significantly longer distance
than the optimum separation (7.3 ) for a DC site.[44] Nachti-
gall et al.[45] propose a model to control the adsorption en-
thalpy of CO2in zeolites by framework topology and compo-
sition. Results have been collected for a series zeolites types
(e.g., MFI, FER, FAU, LTA, TUN, IMF, and SVR) with dif-
ferent structures and compositions. The strongest interaction
can nonetheless occur with extra-framework cations with
a large charge/ionic radius ratio. The cation has to be ade-
quately exposed in the zeolite channel. In addition, disper-
sion interactions depend on zeolite topology (channel diame-
ter) and on channel wall thickness (framework density).[46] A
large CO2adsorption heat occurs in zeolites that have a maxi-
mal effect of the bottom (e.g., Li+cations on the intersection
site formed by two 10-ring channels) or in zeolites with
a large number of DC sites (e.g., a pair of Na+cations in
two neighboring 8-rings in FER). In a recent report, Kim
et al.[47] prepare zeolites with Si/Al values in the order SSZ-
13 (16.44), ZSM-5 (16.08), Y (2.82), SAPO-34 (0.19), where-
as high CO2adsorption capacity is obtained for SSZ-13 and
SAPO-34 with a CHA framework. The FAU zeolite Y with
the highest microspore volume exhibits less CO2adsorption
than the CHA zeolites, and the MFI-type ZSM-5 yields the
poorest performance.
Table 1. Comparison of equilibrium CO2and N2selectivity of different ad-
sorbents at 0.1 MPa.
Adsorbent Temperature
[K]
Selectivity of CO2/N2Ref.
zeolite 13X 198 17.0 [36]
zeolite NaY 303 14.5 [37]
molecular sieves (5 ) 293 4.7 [38]
ZSM-5 313 5.4 [39]
zeolite-b303 12.4 [39]
SAPO-43 298 15.4 [40]
MIL-53 303 10.1 [40]
activated carbon 293 6.1 [40]
zeolite CaL 303 31.0 [41]
zeolite SrL 303 21.8 [41]
Cu and H-SSZ-13 298 33.1 [42]
SAPO-56 273 42 [43]
SAPO-RHO 273 84 [43]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VC H Verlag GmbH & Co. KGaA, Weinheim
&
5
&
These are not the final page numbers! ÞÞ

4.1.2. CO2adsorption on zeolites at high temperatures
A broad range of operating temperatures and pressures is
vital in practical applications of CO2adsorption on different
adsorbents at relatively high temperatures. Processes for CO2
capture by using zeolites from moderate-pressure and high-
temperature gas streams have attracted the attention of sev-
eral industries, in particular, the fields of gas separation and
gas purification at relatively moderate pressures. The CO2
adsorption capacity of zeolites usually diminishes rapidly as
the temperature of the gas being separated increases. Addi-
tionally, moisture sorption contributes to a decrease in the
CO2capture capacities.[47] Wei et al.[48] have synthesized NaY
zeolite particles with high surface areas and have measured
the adsorption isotherms of single gases (CO2and N2) on the
NaY zeolite at temperatures from 303 to 473 K and pressures
up to 100 kPa. A comparison of the CO2adsorption iso-
therms measured in their work with those reported in the lit-
erature has also been made. Comparative studies of CO2and
N2on synthesized NaY particles at different temperatures
are shown in Figure 3a, b. In addition, the pore-size distribu-
tion plot is represented in Figure 3c, from which it can be
observed that the synthesized NaY zeolite particles exhibit
a unique pore-size distribution. The amount of CO2adsorbed
on the NaY zeolite is remarkably larger than the amount of
N2adsorbed within the experimental range of temperatures
and pressures. For instance, the quantities of adsorbed CO2
and N2are 4.8 and 0.33 mol kg1at 303 K and 100 kPa, re-
spectively. Moreover, Figure 3 d compares the quantities of
CO2adsorbed on NaX, ZSM-5, 13X, zeocarbon, and natural
zeolites. The CO2adsorption isotherms reported by Wei
et al.[48] and by Walton et al.[50] show that higher quantities of
CO2are adsorbed on NaY zeolites than on other zeolites at
a pressure of approximately 80 kPa (see Figure 3d), and the
amount of CO2adsorbed is approximately 4.6 mol kg1at
303 K. The CO2adsorption reported by Wei et al.[48] is ap-
proximately 4.9 molkg1at 298 K. These results reveal that
the adsorption of CO2measured by Wei et al.[48] is apparently
higher than that measured by Walton et al.[50] at pressures
below 50 kPa. This indicates that the interaction between the
weak quadrupole moment of N2and NaY does not introduce
significant heterogeneity for N2adsorption. In contrast, the
Figure 3. Experimental adsorption isotherms of a) CO2and b) N2on the synthesized NaY zeolite at temperatures from 303 to 473 K and pressures up to
100 kPa. c) Pore-size distribution of NaY zeolite. d) Adsorption isotherms of CO2on synthesized NaY-303K,[48] NaY-298K,[50] 13X-295K,[48] NaY-295K,[48] NaX-
300K,[52] 13X-293K,[58] zeocarbon-293K,[58] ZSM5-295K,[47] and natural zeolites-298K.[64]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VC H Verlag GmbH & Co. KGaA, Weinheim
&
6
&
These are not the final page numbers! ÞÞ

decrease in CO2adsorption on the basis of the increased
temperature can be elucidated by the strong interactions be-
tween the quadrupole moment of CO2and the NaY zeolite
adsorbent.
Cavenati et al.[49] report the effects of temperature on the
CO2adsorption capacities of H-ZSM-5, 3X, 5A, Li-ZHM,
and MCM-4. As presented in Table 2, increasing the temper-
ature and pressure has a negative influence on the per-
formance of the zeolite adsorbents in the gas mixtures.
4.1.3. CO2adsorption on ion-exchange zeolites
Alkali metal ions such as Na+in zeolites are responsible for
compensating the negative charge of the AlO4tetrahedra,
and these Na+ions can be replaced by other mono- and/or
divalent cations such as Li+,K
+,Mg
2+,Ca
2+, and Ba2+. Ion-
exchange techniques involving the use of an aqueous solu-
tion of the corresponding precursors allow desired surface
and electronic properties to be obtained that are suitable for
high CO2adsorption and better CO2selectivity from other
gas streams. The basicities of zeolites with group IA cations
follow the order Cs+>Rb+>K+>Na >Li+>H+; these
zeolites have two kinds of adsorption sites for CO2that have
weak Lewis acid character: extra-framework cations and sur-
face oxygen atoms.[50] A significant study published by Liu
et al.[51] describes the ion exchange of Na+for K+in zeolite
4A, which is a crystalline material that consists of a zeolite
A-type structure. This zeolite can be synthesized by precipi-
tation and crystallization from pure sodium aluminate and
sodium silicate solutions, and the product has a composition
of Na2O·2SiO2·Al2O3·4.5 H2O ; replacement of sodium with
potassium results in the potassium-exchanged type A zeolite
(NaKA zeolite). This species contains 23.5% of its exchange-
able cation sites occupied by potassium ions [NaK (23.5%)
A zeolite]. This is mainly known as sodium–potassium ade-
nosine triphosphate and is also known as NaKA zeolite. Se-
lectivity for CO2over N2can be reached (3.43 mmolg1),
whereas the total CO2uptake remains high at a specific K+
/(K++Na +) ratio at 17 %. As shown in Figure 4a, the high
selectivity is due to a sieving effect resulting from an effec-
tive pore diameter lying right in between the kinetic diame-
ters of CO2and N2. This allows the material to adsorb CO2
while effectively blocking out N2. The high selectivity of CO2
over N2is obtained for a series of zeolites synthesized with
the NaKA sorbent at 298.15 K and 85 kPa. Optimal K+ion
adsorption and a significant quantity of adsorbed CO2are re-
ported.
The relative populations of the K+and Na+ions in the
three sites are shown in Figure 4a.[52] Furthermore, Figure 4 c
reveals that K+replaces Na+mainly at site II with a K+
level of 40%; thus, K+ions almost fully occupy site II. The
presence of K+at site III is too small to yield a certain K+
/Na+ratio for this site, whereas site I starts to be occupied
by K+, which leads to a dramatic decrease in the amount of
CO2adsorbed.
4.1.4. CO2adsorption on zeolites: heat adsorption
The isosteric heat of adsorption is a critical design variable
in estimating the performance of an adsorptive gas separa-
tion process and is used to measure the interaction between
an absorbent and the adsorbent molecules in addition to the
energetic heterogeneity of the adsorbent surface. Seok
et al.[53] have studied the adsorption of CO2on a series of
zeolite X/activated carbon composites to examine the effects
of the relative proportions of zeolite X and activated carbon
in the composites and their surface modification upon CO2
adsorption. This study was performed to develop a novel
CO2adsorbent with the advantages of both the zeolite and
the activated carbon region, which remains essentially con-
stant and becomes nearly independent of loading in the high-
loading region. Second, the average heat of adsorption de-
creases after modification. These results indicate less surface
heterogeneity and weaker adsorbate–adsorbent interactions
on the modified composites than on the unmodified ones.
The amount of adsorption of an adsorbent depends on the
available surface area and the affinity for an adsorption gas.
Adsorbents used for gas separation should have an affinity
based on the physical interactions between the surface of the
adsorbents and the adsorbate molecules, as the adsorption–
desorption processes should be reversible. Increasing the
physical affinity leads to an increase in the adsorption capaci-
ty. The results obtained by Bonenfant et al.[54] demonstrate
the influence of the structural characteristics of the zeolites
on CO2adsorption, and it is considered that the fundamental
properties of the zeolites generated by the different electron
densities of the framework oxygen atoms allow for strong ad-
sorption of the acidic CO2molecules. They conclude that for
the modified composite the adsorption selectivity of CO2/N2
will be higher than that for the unmodified composites and
that the adsorption heat, especially in the low-loading re-
gions, will be lower than that for the unmodified composites.
Several authors have concluded that the decrease in the iso-
steric heat of adsorption with the introduction of Cr3+to
NaX zeolites can be attributed to weakening of the electro-
static fields present within the zeolite cavities. This phenom-
enon suggests that the interaction between CO2and the zeo-
lite surface decreases with the CO2loading. The adsorption
of CO2on NaY has a similar weakening interaction between
Table 2. Effect of pressure and temperature on the CO2adsorption capaci-
ty of different types of zeolites.
Zeolite Type Temperature
[K]
Pressure
[kPa]
CO2adsorption
[mmolg1]
Ref.
H-ZSM-5 281 82 2.14 [37]
309 89 1.869
13X 273 102 4 [39]
353 102 2
5A 303 120 3 [44]
373 120 0.239
Li-ZHM-5 303 200 1.418 [45]
333 200 1.376
MCM-41 323 101.3 0.325 [49]
373.15 101.3 0.150
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VC H Verlag GmbH & Co. KGaA, Weinheim
&
7
&
These are not the final page numbers! ÞÞ

CO2and the zeolite cavity with the CO2loading, which could
result in a decrease in the isosteric heat of adsorption.
4.1.5. Morphology control in the synthesis of zeolites for CO2ad-
sorption
Morphology control plays a significant role in enhancing
CO2adsorption, as the morphology dictates the surface area
and pore volume, provides easy access to the actives sites,
and supports the interparticle diffusion of gases. Zeolite mor-
phology is sensitive to the synthetic conditions. Hence, it is
essential to examine the synthetic parameters that affect the
crystal size and shape.[55] Nevertheless, it is still a challenge
to fabricate a suitable morphology for a required zeolite be-
cause of the complicated relationship between zeolite mor-
phology and the synthetic conditions. Insuwan and Rangsri-
watananon[56] have synthesized zeolite L, a crystalline alumi-
nosilicate compound with the composition
K9Al9Si27O72·nH2O(n=0–36). Variations in the chemical
composition have different effects on the morphology and
crystal size. The morphologies vary from ice hockey particle
to cylindrical shapes, and their crystals range in size from
1.50 to 7.53 mm as a function of increases in H2O and SiO2;
the crystal size also increases. Displayed in Figure 5 are the
SEM images of the zeolite L samples synthesized with vari-
ous aluminum contents. The synthesis gels with molar com-
positions of 2.62K2O/bAl2O3/10 SiO2/160H2O, for which b=
0.8, 1.0, 1.2, and 1.4, have been investigated. The results dem-
onstrate that only the cylindrical shape of all the zeolite L
morphologies is found at 0.8 and 1.4 moles of Al2O3, whereas
the shapes at 1.0 and 1.2 moles have a pure crystalline phase
of zeolite L with cylindrical shapes of 7.53 and 6.50 mm, re-
spectively. The channel length decreases with an increase in
the Al(OH)3content (see Table 3).
Akhtar et al.[57] have prepared nanocrystalline zeolite NaA
with thermoreversible polymerized methylcellulose (MC) hy-
drogel by template-free hydrothermal synthesis in thermore-
versible methylcellulose gels. The results reveal that the ther-
Figure 4. a) Illustration of the structural mechanism of the K+ions as a function of open pore windows in NaKA zeolite. b) Uptake of CO2and N2(298.15 K,
85 kPa) in NaKA. c) The Na +occupancies of different ionic sites obtained from Rietveld refinement of the powder X-ray diffraction data.[43]
Figure 5. SEM images of zeolite L crystals synthesized from compositions
2.62K2O/bAl2O3/10 SiO2/160 H2O, for which b=0.8 (a), 1.0 (b), 1.2 (c), and
1.4 (d).[56]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VC H Verlag GmbH & Co. KGaA, Weinheim
&
8
&
These are not the final page numbers! ÞÞ

mogelation of methylcellulose in the alkaline Na2O–SiO2–
Al2O3–H2O methylcellulose plays a significant role in con-
trolling the particle size and morphology of the zeolite. The
synthesized nanocrystalline zeolite NaA shows that nanocrys-
tals with a size of 100 nm display a high CO2uptake capacity
(4.9 mmolg1at 293 K at 100 kPa). Lin et al.[58] have synthe-
sized a new class of MCM-41 mesoporous silica materials
with different functional groups prepared by a condensation
method. The presence of various amounts of organo-alkoxy-
silane precursors during the condensation has a prominent
effect on the final particle shape through changing the con-
centration of its precursor; the particle morphology can be
tuned to different shapes, including tubes, spheres, and rods,
of various dimensions. The morphology control of these ma-
terials will prompt their utilization in gas separation, sensor
design, and catalysis.
4.1.6. Kinetic theories of CO2adsorption isotherms in zeolites
Kinetic properties with equilibrium adsorption properties are
crucial for evaluating the overall performance of zeolites and
MOFs; the performance of a zeolite in kinetic separation is
directly related to the pore size and shape of the adsorbent.
The pore size and shape are constantly the first considera-
tions in selecting a zeolite for a special separation. Molecular
sieves have been widely used in zeolites and other porous
materials for gas separation. There are several results and
models regarding the sorption of CO2and CH4in zeolites.
The basics to analyze such thermodynamic data are de-
scribed in different varieties of models, such as Langmuir,
dual-site Langmuir, Fowler, and Nitta, all of which are used
extensively because of their simplicity and thermodynamic
consistency, and they provide comprehensive insight into
sorption events.[57] The Langmuir equation is a simple and
suitable model to represent type I isotherms [Eq. (1)]:
1
pþq
1q¼bð1Þ
in which q=q/qmis the degree of filling on the sites, bis an
equilibrium constant, pis the pressure, qis the amount ad-
sorbed, and qmis the amount adsorbed at the saturation of
the adsorbent. To improve interactions between adsorbed
molecules, Fowler proposes the following equation [Eq. (2)]:
1
pþq
1q¼bexpð2wq
RT Þð2Þ
in which wis the extra energy if sorbate molecules occupy
adjacent sites (positive for repulsion, negative for attraction),
Ris the ideal gas constant, and Tis the temperature. Verifi-
cations for both models 1 and 2 can be simply proved by
plotting log 1
pþq
1qversus q.
If the results show a horizontal line, the Langmuir model
is valid. If the Fowler isotherm equation is a line, it will show
as a straight line with slope 2w/RT. The relationship be-
tween the Fowler model behavior toward the heat of adsorp-
tion displays the mathematical interpretation.
According to Equation (2), the isosteric heats of sorption
for CO2and CH4can be estimated from a plot of (ln Pvs. 1/
T) at constant loading. A linear decrease in the isosteric heat
of sorption upon increasing the CO2amount will be clearly
observed. The practical constancy of the isosteric heat for
CH4could be attributed to the wparameter in Equa-
tion (2).[58] If there is an affinity of interaction energies, the w
parameter will be negative, and we will observe an increase
in the heat of absorption. In contrast, if wis positive, the in-
teraction energies will be repulsive, and the heat of absorp-
tion will decrease linearly. There are several adsorbents pub-
lished by Barrer and Ruthven;[59, 60] these adsorbents are as-
cribed to the polarizing effects of cations in the framework
and CO2that lead to energetic heterogeneity of the sites. In
this case, the balance between the adsorbate–adsorbent inter-
action energies is clearly shown in the wparameter and, con-
sequently, in the exponential of the Fowler isotherm, which
leads to the observed experimental behavior. The diffusivity
of CO2in the zeolites is another parameter that should be
considered to evaluate the performance of CO2capacities.
Sabouni[61] has investigated the kinetics of CO2adsorption in
a new class of CPM-5 zeolites. The kinetics data are in the
pressure range from 5 to 105 kPa at temperatures of 273,
298, and 318 K and were acquired by using a micrometric
BET instrument based on the classical microspore diffusion
model, as shown in Equation (3) with only 99 %>(mt/m1)>
70%.
1mt
m1¼6
p2exp½p2Dct
r2cð3Þ
in which rc is the particle radius [m], and the diffusivity
(Dc[m2s1]) can be calculated from the slope of the linear
plot of ln (1mt/m1) versus time (t) at a given pressure.
The results obtained from Equation (3) indicate that the
zeolite can reach CO2saturation capacity as a function of
temperature, pressure, and CO2diffusivity in the zeolites.
The differences in the results can be related to the particle-
size distributions. Moreover, given the high exothermic
nature of CO2adsorption, the selectivity of CO2is low rela-
tive to that of N2,H
2O, and CH4above 308C and becomes
insignificant after 2008C. Moreover, the small size and linear
Table 3. Chemical compositions of zeolites L after a reaction time of
2 days at 180 8C.
Chemical composition
K2O/Al2O3/SiO2/H2O
Crystallinity of
zeolite L [%]
Average particle
size [mm]
Morphology
(particle shape)
2.78:1.00 :10 :00:160.00 98.3 2.49 ice hockey
2.62:1.00 :10.00 :160:00 91.70 7.62 long cylindrical
2.62.1.00:9.00 :160.00 N.A. 3.39 short cylindrical
2.62:1.00 :10.00 :180:00 N.A. 1.56 ice hockey
2.62:1.00 :10.00 :200:00 N.A. 11.26 cylindrical
[a] N.A. =not available.
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VC H Verlag GmbH & Co. KGaA, Weinheim
&
9
&
These are not the final page numbers! ÞÞ

structure of CO2allow the adsorption of CO2in different
zeolites to be considered at low temperatures.[62]
5. Synthesis of Metal–Organic Frameworks for
CO2Capture
Metal–organic frameworks have recently emerged as a new
class of porous materials with tailorable structures and func-
tional linkers owing to the possibility of obtaining a large va-
riety of interesting structures that can also be useful for ap-
plications in the fields of porous materials. This includes the
most conventional areas of storage, separation, and catalysis,
which are based on pore size and shape, as well as the host–
guest interactions involved. Also, biomedical applications
and use as sensor materials are currently under intensive in-
vestigation.[63] The relationships among porous structures,
window sizes, selectivity, capacity, and enthalpy of porous
MOFs for CO2adsorption can provide ideas for the design
and synthesis of MOF materials as CO2adsorbents.[64] Fig-
ure 6a represents the synthesis method for MOFs on the
basis of different substrates, and the synthesis procedures
depend on the diffusion direction of the metal ion and the
linker in the crystallization process.[65] These processes can
be divided into three broad categories: hydrothermal or sol-
vothermal method, interfacial (counterdiffusion) method,
and liquid-phase epitaxy (layer-by-layer) method. High stor-
age capacity is possible, and the heat required for recovery
of the adsorbed CO2is relatively low. Over 600 chemically
and structurally diverse MOFs have been developed over the
past several years.[66] Willis et al.[67] have developed MOF-177
to achieve the highest surface areas and CO2adsorption ca-
pacities at moderate pressure. Additional work is required to
determine its stability over thousands of cycles and the effect
of impurities on typical flue gas temperature and pressure.
Improvements in the affinity of MOFs for CO2can be ob-
tained by functionalization of either the internal pore surface
or the surfaces of the material. Surface modification of nano-
crystalline MOFs can enhance both selectivity and stability,
but it can also be used to tailor the hydrophobic/hydrophilic
properties. Functionalization of the internal pores can occur
by using suitable functional linkers in the synthesis. The pres-
ence of amino groups and halides has been revealed to in-
crease the affinity of MOFs for CO2. Several functional
chemicals, such as 2-aminopyrazine and 2,5-diaminopyrazine,
have been used postsynthetically to coordinate unsaturated
metal centers in MOFs. However, this modification usually
leads to reduced absorbing capabilities because of the re-
duced pore volume of the modified materials. An alternative
method is to graft a functional monomolecular layer or new
MOF layers on the surfaces of nanocrystalline MOFs
through in situ or postsynthetic modification. This surface
modification is anticipated to enhance both the selectivity
and capacity. Figure 6b represents the designed interior of
a MOF for CO2capture in the presence of water. The interi-
or of IRMOF-74-III is covalently functionalized with a pri-
mary amine (IRMOF-74-IIICH2NH2) and is used for the se-
lective capture of CO2at 65 % relative humidity. The results
demonstrate that this MOF is able to uptake CO2(3.2 mmol
of CO2per gram at 0.1 MPa) and, more significantly, is able
to remove CO2from nitrogen gas streams.[68–72]
5.1. CO2adsorption in MOFs
The factors that increase CO2adsorption are based on in-
creases in porosity and surface area of the MOF, which lead
to an increase in the length of the linker between the metal
vertices. However, a drawback often occurs as a result of
framework collapse owing to the lack of linker rigidity. This
occurs because of interpenetration or the growth of two latti-
ces within one another. Yaghi and co-workers[73] report that
two failure modes for linker expansion can be overcome by
joining extended linkers with proper topology selection. A
previously synthesized MOF, that is, MOF-177, is first ex-
panded to yield MOF-180 and MOF-200, which exhibit 89
and 90% porosity, respectively. Surface area estimates by
Brunauer–Emmett–Teller (BET) adsorption are not avail-
able for MOF-180, but MOF-200 possesses a surface area of
4530 m2g1. In contrast, MOF-177 exhibits a surface area of
4500 m2g1and a porosity of 83%. Most of the MOFs con-
tain a single type of linker to connect the metal clusters.
Blending two different types of linkers allows for additional
topologies; this concept has been explored in the formation
of MOF-210 from the reaction of two linkers. MOF-210 dis-
plays an entirely new topology but exhibits exceptional po-
rosity (89 %) and a high surface area (6240 m2g1). Figure 7
Figure 6. a) Synthesis methods of MOF-based membranes and b) synthesis
methods for continuous membranes.[72]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
10
&
These are not the final page numbers! ÞÞ

shows the unique topology of MOF-210, which consists of
two types of pores.
Yaghi et al.[74] report the highest amounts of excess CO2
uptake and total H2uptake for MOFs among MOF-180,
MOF-200, MOF-205, and MOF-210. MOF-210 shows sur-
passing uptake quantities of 2400 mg g1(298 K and 60 bar)
and 176 mg g1(77 K and 70 bar) for CO2and H2, respective-
ly (Figure 7a–d). Excess CH4uptake for MOF-210 is also
among the highest values, up to 264 mgg1at 298 K and
80 bar. The high adsorption capacity for this series of MOFs
is attributed to the ultrahigh surface areas (up to
6240 m2g1), void volumes (up to 90%), and pore volumes
(up to 3.59 cm3g1) associated with low crystal densities (as
low as 0.22 g cm3). These results for the adsorption iso-
therms at high pressure are mostly affected by the surface
areas of the MOFs (Table 4), for which the greatest adsorp-
tion isotherm capacities are obtained for MOFs with high
surface areas.
5.1.1. CO2adsorption over CH4and N2in MOFs
The selective adsorption of CO2over CH4and N2depends
on the influence of molecular sieving, which has been con-
firmed in some MOFs. This effect is estimated by the sizes
and shapes of both gas adsorbates and the pores in the MOF.
The highly selective adsorption of CO2over N2is attributed
to the small aperture of the channels in the MOF, in addition
to the small window size, and is based on size/shape exclu-
sion, as in MIL-96 {Al12O(OH)18(H2O)3(Al2(OH)4[benzene-
1,3,5-tricarboxylate (btc)]6}.[75] In addition, a MOF replete
with open magnesium sites has been reported. Mg-MOF-74
[Mg2(DOT); DOT=2,5-dioxidoterephthalate] has sufficient
selectivity, can be regenerated in a facile manner, and has
one of the highest dynamic capacities reported for CO2in
MOFs. The synthesis of this material has been confirmed by
single-crystal structure determination of Mg-MOF-74, and it
is formed by reaction of DOT linked with Mg(NO3)2·6H2O.
The structure contains 1D inorganic rods linked through
DOT to form linear hexagonal channels. In Figure 8a, the C
atoms are displayed in gray, the O atoms are displayed in
red, six-coordinate Mg atoms and terminal ligands are shown
in pink, and five-coordinate Mg atoms are depicted in blue.
The H atoms and terminal ligands on the fragment at the top
right are omitted for clarity. This unique Mg-MOF-74 struc-
ture has been subjected to a gas stream containing 20 % CO2
in CH4, a percentage in the range relevant to industrial sepa-
rations,[76] and it selects only CO2and releases CH4gas. The
pores retain 89 g of CO2per kilogram of material before
breakthrough, a value higher than any other achieved for
a MOF and that rivals the highest capacities in zeolites. Re-
markably, 87% of the captured CO2can be enhanced at
room temperature, and the remaining amount can be re-
moved by mild heating (808C).[77]
The results shown in Figure 8b reveal that the adsorption
of CO2in this MOF is highly favored over the adsorption of
CH4with a dynamic capacity of 8.9 % CO2uptake. The high
uptake of CO2for Mg-MOF-74 is attributed to strong inter-
actions between the oxygen lone pair orbitals of CO2and the
coordinative unsaturated metal cations, and this has been de-
termined on the basis of the results obtained from interac-
tion between CO2and isostructural Ni2. Nonetheless, several
reports prove that the presence of any moisture in the gas
Figure 7. Structures of MOF-200 and MOF-210 and their gas adsorption abilities for a) N2, b) H2,c)CH
4, and d) CO2relative to the gas adsorption abilities of
related MOFs.[73] 1 bar=0.1 MPa.[74]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
11
&
These are not the final page numbers! ÞÞ

Table 4. Comparison of the experimental results of CO2diffusivity.
Material[a] Code name Surface area [m2g]Tuptake Pressure[b] Capacity Ref.
BET Langmuir [K] [atm] [molg]
Zn4O(BTB)2MOF-177 5400 4690 298 1.2 5.2 [73]
VIVO(BDC) MIL-47 600 872 298 1 1.8 [74]
Al(OH)(bpydc) MOF-253 2160 2490 298 1 3.2 [75]
Zn4O(BDC)3MOF-5, IRMOF-1 2304 2517 296 1 [76]
Zn(almeIm)2ZIF-93 864 298 1 2.3 [77]
H3[(Cu4Cl)3(BTTri)8] Cu-BTTri 1770 1900 298 1 3.5 [78]
Zn4O(PDC)3IRMOF-11 2096 298 1 3.8 [79]
Zn4O(BDC-NH2)3IRMOF-3 2160 298 1.1 4.3 [80]
Cu2(bptc)(H2O)2(DMF)3MOF-505 1547 296 1 2.3 [81]
Al(OH)(2-amino-BDC) NH2MIL-53(Al) 960 298 – [82]
Zn4O(BDC-C2H4)3IRMOF-6 2516 298 – 3.8 [83]
Ni2(BDC)2(DABCO) USO-2-Ni 1925 – 3.2 [84]
Cu3(BPT)2UMCM-150 296 10.2 [85]
[a] BTB: benzene-1,3,5 tribenzoate, BDC : 1,4-benzene-dicarboxylate, bpydc: 2,2-bipyridyl-5,5-dicarboxylate, BTTri: 1,2,3-(triazol-5-yl)benzene, PDC :phenyldi-
carboxylic acid, BDC-NH2: benzene-1,4-dicarboxylate amino, bptc: 4,4 biphenyldicarboxlate, BDC-C2H4: benzene-1,4-dicarboxylate ethylene, DABCO: 1,4-dia-
zabicyclo (2,2,2), BPT: bis(4-pyridyl)-1,2,4,5-terrazine) [b] 1 atm =0.1 MPa.
Figure 8. a) Synthesis process of Mg-MOF-74-DMF through solvent exchange, b) 20 % mixture of CO2in CH4in a fluidized bed column with Mg-MOF-74.[78]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
12
&
These are not the final page numbers! ÞÞ

stream has an unfavorable effect on the CO2adsorption per-
formance of M-MOF-74. In the case of Mg-MOF-74, which
retains a higher dry capacity for CO2than the isostructural
Zn, Ni, and Co structures, Matzger et al.[78] show that after
exposure to 70% relative humidity (RH) in CO2/N2, a de-
crease in performance is observed at all temperatures, with
the MOF retaining only 16 % of its original CO2capacity.
Comparative studies of the differences in the combustion
gases (CO2/N2and CO2/CH4) have been conducted by sever-
al researchers, as described in Table 5, which presents the
high selectivity of CO2as a function of the high performance
of the MOFs. In selective adsorption, both capacity and se-
lectivity have been the primary concerns in most research
performed to date, but single-component isotherms and the
ideal adsorbed solution theory (IAST)[79] have also been
used to calculate the selectivity factors of materials. Like-
wise, this provides a simple way of evaluating the per-
formance of different MOFs in terms of selectivity.
5.1.2. MOF membranes for CO2adsorption
Research on MOF membranes for gas separation is currently
in its primary stages in terms of high efficiency for the ad-
sorption of CO2molecules.[83] Table 6 highlights selectivity
studies for mixture-gas-based CO2capture over N2in MOF
membranes. For example, mixtures and functionality of the
IRMOF-1 membrane play significant roles in estimating the
performances of the MOF. Further investigations on the per-
formance of chemically diverse MOFs (i.e., MOF-5, NIF-7,
NIF-8, NIF-22, and HKUST) for membrane separation of
CO2/N2are summarized in Table 6. Gas-mixture properties,
such as diffusion rate and polarity, are important factors to
take into consideration toward the performance of MOF
members. However, many of these initial reports on MOF
membranes have included single gas permeation data for
common gases, including CO2and N2.
Bu and co-workers[107] report a series of isostructural
porous MOFs that are synthesized by the reaction of NiII
with 2,4,6-(4-tripyridinyl)-1,3,5-triazine (tpt); o-phthalic acid
(OPA) with various functionalities (H, NH2,NO2, and 
F) is used as a co-ligand (Figure 9a). Crystallographic analy-
sis demonstrates that all structures possess a 3 D porous
framework with chiral channels that are decorated with func-
tional groups. MOFs with different numbers of fluorine
atoms and in different positions (e.g., TKL-104, TKL-105,
and TKL-106) have been studied, and TKL-107 MOF has
been used to fabricate matrices membranes, which exhibit
great potential for CO2separation. The CO2uptake quanti-
ties of the fluorinated MOFs (at 273 K and 1.2 bar) are
33 cm3g1for TKL-104, 105 cm3g1for TKL-105, 126 cm3g1
for TKL-106, and 150 cm3g1for TKL-107. The high CO2
uptake and selectivity over N2and CH4make these fluorine-
functionalized MOFs superior candidates for CO2sequestra-
tion. A high selectivity of the quantity adsorbed (42 wt%) at
high pressure (30 bar) has been recorded for TKL-107 (Fig-
ure 9c). Furthermore, TKL-107-doped mixed matrices mem-
branes (MMMs) have been synthesized, and the CO2and
CH4permeation experiments display values of 64.6 and 50.3
for a selectivity content of 20% (Figure 9d).
Smith et al.[108] report postsynthetic Ti-exchanged UiO-66
into the Zr UiO-66 MOF for the separation of CO2from
flue gases. The SEM images in Figure 10 demonstrate that
Table 6. MOF membranes with N2and CO2permeabilities and CO2/N2
ideal selectivities.
MOF Permeability[a] [Barrer] CO2/N2Ref.
CO2N2
MOF-5 10 000 12 000 0.8 (DP200 kPa at 25 8C) [95]
MOF-5 17 000 20 000 0.8 (DP101.3 kPa, 258C) [96]
MOF-5 28 000 34 000 0.8 (DP101.3 kPa, 258C) [97]
NIF-7 16.5 16.5 1.0 (DP100 kPa, 200 8C) [98]
NIF-7 7 4.4 1.6 (DP100 kPa, 220 8C) [99]
NIF-8 532 208 2.6 (DP100 kPa, 25 8C) [100]
NIF-8 890 298 3.0 (DP101.3 kPa, 25 8C) [101]
NIF-22 952 1136 0.8 (DP100 kPa, 508C) [102]
NIF-90 696 396 1.8 (DP100 kPa, 200 8C) [103]
MMOF 7.0 70 1.0 (DP101.3 kPa, 25 8C) [104]
HKUST 17000 16 000 1.0 (DP100 kPa, 25 8C) [105]
HKUST 12500 12 500 1.0 (DP101.3 kPa, 25 8C) [106]
KHUST 5500 3750 1.5 (DP101.3 kPa, 190 8C) [107]
MIL-53 960 1120 0.86 (DP800 kPa, 25 8C) [108]
[a] 1 Barrer =7.5·1018 m3skg1.
Table 5. High selectivity of CO2based on high performance of MOFs.
Chemical formula[a] Common name Selectivity
CO2/N2CO2/CH4
CO2concen-
tration
Pressure[b]
[bar]
T
[K]
Ref.
Mg2(DOBDC) Mg-MOF-74 49 16 1 298 [85]
Zn2(BPDC)2(BPEE) 294 257 16 1 298 [86]
(Ni2L2)(bptc) SNU-M10 98 50 1 298 [87]
Cu3(TDPAT)(H2O)3Cu-TDPAT 34 16 1 298 [88]
Cu3L2(H2O)5NJU-Bai3 25–61 14–47 50 1 298 [89]
Cu3(BTB6-), Cu3(TATB6-) 34 9 50 1 273 [90]
H3[(Cu4Cl)3(BTTri) Cu-BTTri 21 50 1 298 [91]
Al(OH)(NDC) 20 4 50 1 273 [92]
Cu2(bttcd) PCN-80 12 50 1 296 [93]
[Ln2(TPO)2(HCOO)]·(Me2NH2) 28 50 1 298 [94]
[a] DOBDC:1,4-dioxido-2,5-benzenedicarboxylate, BPDC : biphenyle-4,4-dicarboxylate, BPEE: 1,2-bis(4-pyridyl)ethylene, bptc : 1,2-bis(4-pyridyle)ethene, TDPAT:
2,4,6-tris (3,5-dicarboxylphenylamine)-1,3,5-triazine), BTB6 : benzene 1,3-tribenzoic acid, TATB6:triazine-2,4,6-triyl-tribenzoate, BTTri: 1,2,3-(triazol-5-yl)ben-
zene, NDC: 2,6-naphthalenedicarbocylate 4,4, bttcd: octa-carboxylte ligand [b] 1 bar =0.1 MPa.
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
13
&
These are not the final page numbers! ÞÞ

TixUiO-66 agglomerates as a function of MOF loading and
Ti exchange, and this agglomeration increases the effective
particle size. The differences in the CO2permeability, solubil-
ity, and diffusivity values reveal that the various polymers
are microporous without containing a network of covalent
bonds, and this is called the polymers intrinsic microporosity
(PIM) synthesis protocol. The decrease in the solubility coef-
ficients of the MOF-loaded membranes is based on an in-
crease in the amount of Ti incorporated. In particular, titani-
um exchange in the Ti5UiO-66 membrane significantly im-
proves both the solubility and the diffusivity coefficients over
the corresponding native UiO-66 membrane. Therefore, Ti-
exchanged UiO-66 shows a significant increase in membrane
CO2permeability relative to that of the non-exchanged
membrane.
Figure 9. a) General route for the synthesis of TKL MOF. b) CO2adsorption isotherms at 273 K and low pressure. c) High-pressure CO2and CH4adsorption iso-
therms at 273 K. d) CO2/CH4selectivity and permeability trend of the TKL-107 MMMs.[107]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
14
&
These are not the final page numbers! ÞÞ

5.2. Potentials and limitations for CO2capture
According to recent technologies, there are still challenges in
particular in the design of superior materials for highest effi-
ciency of CO2capture. These complex issues will almost cer-
tainly require the integration of several technology options.
This review has sought to highlight the parameters that
affect CO2separation methods that have the greatest pros-
pect of reducing CO2emissions into the atmosphere. The fol-
lowing points can be summarized:
1) Zeolites with low Si/Al ratios are promising adsorbents
for CO2adsorption and separation applications. However,
CO2adsorption on zeolites still possesses some limita-
tions, as zeolites are strongly affected by temperature,
pressure, and the presence of water. Alternatively, MOFs
have low thermal stability and mechanical properties
owing to their large porosities and surface areas.
2) The Brønsted acid sites and hydroxyl nests within the
zeolite frameworks need to be re-evaluated at high tem-
peratures through decomposition mechanisms within zeo-
lites. Nevertheless, ion exchange in the pores of the zeo-
lites leads to increased thermal stability, whereas MOFs
possess high CO2capacities with fast kinetics adsorption
and moderate heats of sorption at room temperature.
3) Exchange with alkaline-earth and alkali cations in zeolites
enhances CO2adsorption. However, amine-functionalized
MOFs exhibit better CO2separation performance over
N2and CH4.
4) Zeolite adsorption kinetics are particularly favorable for
CO2adsorption under mild operating conditions (0–
1008C, 0.1–1 bar CO2). However, MOFs show their extra-
ordinary capacity of adsorption at high pressures. MOFs
are relatively unstable for long-term storage.
5) Controlling the structure of MOFs, for example, by in-
creasing the strengths of metal–ligand bonds through the
incorporation of high-valent metal cations (e.g., Al+3and
Ti+4) or more strongly binding ligands (e.g., pyrazoles
and triazoles), can enhance the chemical and thermal sta-
bilities of MOFs. In addition, high-density CO2capture is
basically the result of multiple-point interactions between
the framework and the adsorbate molecules along with its
counteranions.[109,110]
6) MOFs exhibit poorer adsorption at low CO2partial pres-
sures than zeolites. Moreover, MOFs can be synthesized
with tailored properties such as pore size and topography
for high CO2adsorbents at ambient temperature.
6. Conclusions and Outlook
Various technologies such as postcombustion, precombus-
tion, and oxyfuel combustion to capture CO2from a power
plant were discussed. Zeolites and metal–organic frameworks
(MOFs) have common characteristics, including high surface
areas and uniform microspore sizes, but they are different in
terms of mechanical and thermal stability. The progress
made in the field of porous materials for adsorption separa-
tion processing is growing rapidly owing to potential applica-
tions in CO2capture and separation. In particular, new
classes of different zeolites and MOFs were reviewed, and
the relationship between the properties of the MOFs and
their CO2separation potentials were discussed. In addition,
strategies to tailor and design MOFs to enhance CO2adsorp-
tion were briefly considered. Various studies on the general
classification, synthesis, properties, and kinetic theories were
also examined, and it was found that the adsorption process-
es of zeolites and MOFs depend on several parameters, in-
cluding pore volume, surface area, surface properties, and
strength of adsorbate–adsorbent interactions. Moreover, the
CO2adsorption performance of different types of materials,
such as amino chemicals, zeolites, and MOFs, were consid-
ered. The challenges that arise in improving these materials
and techniques are based on several stages. These steps in-
clude the preparation of porous materials for separation,
such as the particle sizes of porous crystals if acting as a sorb-
ent in adsorptive separation. Furthermore, high CO2capaci-
ties were generally shown to correspond to high heats of ad-
sorption in the low-pressure range. As a consequence, the
differences in the heat adsorptions for different gases can be
enhanced if the adsorbent is functionalized with an appropri-
ate molecule. Another important factor is the manipulation
of the porous structure to decrease environmental factors
such as absorption of water, which can cause framework col-
lapse. Further investigation on the scale up of the zeolites
and MOFs and functionalization of these porous materials
will be necessary for the implementation of the process on
a large scale. Hence, optimization of the processes under dif-
ferent conditions may increase significantly the adsorption
capacities and, thus, help to develop efficient technologies to
captures industrial emissions of CO2.
Figure 10. SEM images of PIM-1 Ti5UiO-66 membranes at a,b) 2.6 wt % and
c,d) 15 wt %. Highlighted regions of panels a, c at higher magnification to
identify MOF locations in the images shown in panels b, d, respectively.[108]
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
15
&
These are not the final page numbers! ÞÞ

Acknowledgements
The authors would like to acknowledge financial support
from Agriculture and Agri-Food Canada, the Natural Sciences
and Engineering Research Council of Canada (NSERC), and
the Faculty of Engineering and Architectural Science, Ryerson
University, Toronto, Canada.
Keywords: adsorption ·carbon dioxide ·metal–organic
frameworks ·porous materials ·zeolites
[1] P. Trans, NOAA Research/ESRL, www.esrl.noaa.gov/gmd/ccgg/
trends, accessed 05, July, 2016, and Dr. Ralph Keeling, Scripps Insti-
tution of Oceanography, 2016, scrippsco2.ucsd.edu.
[2] C. H. Yu, C. H. Huang, C.-S. Tan, Aerosol Air Qual. Res. 2012,12,
745–769.
[3] M. Y. Masoomi, K. Stylianou, A. Morsali, D. Maspoch, Cryst.
Growth Des. 2014,14, 2092– 2099.
[4] K. C. Stylianou, W. L. Queen, Chimia 2015,69, 274 – 281.
[5] A. U. Czaja, N. Trukhan, U. Mller, Chem. Soc. Rev. 2009,38,
1284–1293.
[6] R. Kuppler, D. Timmons, Q. Fang, J. Li, T. Makal, M. Young, D.
Yuan, D. Zhao, W. Zhuang, H. Zhou, Coord. Chem. Rev. 2009,253,
3042–3051.
[7] R. Zou, A. I. Abdel-Fattah, H. Xu, Y. Zhao, D. D. Hickmott, Cryst.
Eng. Commun. 2010,12, 1337– 1343.
[8] I. Kim, H. F. Svendsen, E. Borresen, J. Chem. Eng. Data 2008,53,
2521–2529.
[9] S. Keskin, S. Kizilel, Ind. Eng. Chem. Res. 2011,50, 1799–1821.
[10] K. Sumida, D. L. Rogow, J. A. Mason, T. M. McDonald, E. D.
Bloch, Z. R. Herm, T. Bae, J. R. Long, Chem. Rev. 2012,112, 724–
732.
[11] “Carbon Dioxide : Our Common Enemy”: J. T. James, A. Macatan-
gay in SAMAP Submarine Air Monitoring Air Purification, San
Diego, CA, 2009, pp. 25–34 http ://ntrs.nasa.gov/search.jsp?R =
20090029352.
[12] “Compact, Lightweight Adsorbed and Sabatier Reactor for CO2
Capture and Reduction for Consumable and Propellant Produc-
tion”: C. Junaedi, K. Hawley, D. Walsh, S. Roychoudhury, S. Busby,
M. Abney, J. Perry, J. Knox, 42nd International Conference on Envi-
ronmental Systems, San Diego, CA, 2012, pp. 5–14, http ://ar-
c.aiaa.org/doi/pdf/10.2514/6.2012-3482.
[13] R. Matsuda, R. Kitaura, S. Kitagawa, Y. Kubota, T. C. Kobayashi, S.
Horike, M. Takata, J. Am. Chem. Soc. 2004,126, 14063–14071.
[14] B. Dutcher, M. Fan, A. G. Russell, ACS Appl. Mater. Interfaces
2015,7, 2137–2145.
[15] E. J. Welson, D. Gerard, CCS Guidelines: Guidelines for Carbon Di-
oxide Capture,Transportation,and Storage, World Resource Insti-
tute (WRI), Washington, DC, 2008, pp. 12 –19, http://pdf.wri.org/
ccs_guidelines.pdf.
[16] D. M. DAlessandro, B. Smit, J. R. Long, Angew. Chem. Int. Ed.
2010,49, 6058–6082; Angew. Chem. 2010,122, 6194–6219.
[17] W. Di, M. Thomas, Q. Zewei, V. Sergey, P. Zhan, L. Jeffrey, N. Alex-
andra, J. Mater. Chem. A 2015,3, 4248 – 4254.
[18] A. Sayari, Y. Belmabkhout, J. Am. Chem. Soc. 2010,132, 6312 –
6320.
[19] B. Freeman, Program on Technology Innovation: Post-combustion
CO2Capture Technology Development, Electric Power Research In-
stitute, Palo Alto, CA, 2008, pp. 136– 143.
[20] “Post-combustion Carbon Dioxide Capture Presented at the Carbon
Capture Status and Outlook Capture”: M. C. Trachtenberg, R. M.
Cowan, D. A. Smith, in Proceedings of the Sixth Annual Conference
on Carbon Capture and Sequestration, Pittsburgh, PA, 2007, pp. 13 –
21.
[21] Q. Wang, J. Luo, Z. Zhong, A. Borgna, Energy Environ. Sci. 2011,
4, 42–51.
[22] C. Chen, J. Kim, W.-S. Ahn, Korean J. Chem. Eng. 2014,31, 1919–
1934.
[23] A. Sayari, Y. Belmabkhout, R. Serna-Guerrero, Chem. Eng. J. 2011,
171, 760– 771.
[24] G. T. Rochelle, J. Sci. 2009,325, 1652– 1660.
[25] S. Auerbach, K. A. Carrado, P. K. Dutta, Synthesis and Properties of
Zeolite Membrane: Handbook of Zeolite Science and Technology,
Marcel Dekker, New York, 2003, pp. 928–935.
[26] P. D. Vaidya, E. Y. Kenig, Chem. Eng. Technol. 2007,30, 1467– 1475.
[27] A. Adeosun, N. El Hadri, E. Goetheer, M. R. M. Abu-Zahra, Res.
Inventy Inter J. Eng Sci. 2013,3, 12– 23.
[28] J. Johnson, Chem. Eng. News 2008,86, DOI: 10.1021/cen-
v086n007.p005.
[29] J. Gaspar, M. W. Arshad, E. A. Blaker, B. Langseth, T. Hansen, K.
Thomsen, N. von Solms, P. L. Fosbøl, Energy Procedia 2014,63,
614–623.
[30] J. Wilcox, Carbon Capture, Springer, New York, 2012, pp. 8 –14.
[31] A. S. Kovvali, K. K. Sirkar, Ind. Eng. Chem. Res. 2002,41, 2287–
2295.
[32] M. Smiglak, A. Metlen, R. D. Rogers, Acc. Chem. Res. 2007,40,
1182–1191.
[33] J. Li, A. Corma, J. Yu, Chem. Soc. Rev. 2015,44, 7112– 7127.
[34] A. G. Arvalo-Hidalgo, N. E. Almodvar-Arbelo, A. J. Hernndez-
Maldonado, Ind. Eng. Chem. Res. 2011,50, 10259–10269.
[35] M. Laspras, H. Cambon, D. Brunel, I. Rodriguez, P. Geneste, Mi-
croporous Mesoporous Mater. 1996,7, 61–76.
[36] R. Chatti, A. K. Bansiwal, J. A. Thote, V. Kumar, P. Jadhav, S. K.
Lokhande, R. B. Biniwale, N. K. Labhsetwar, S. S. Rayalu, Micropo-
rous Mesoporous Mater. 2009,121, 84– 95.
[37] Y. Yang, B. Shao, J. Zhan, L. Li, R. A. Lee, Microporous Mesopo-
rous Mater. 2008,114, 193– 204.
[38] H. Tsue, K. One, S. Tokita, K. Ishibashi, K. Matsui, H. Takahashi,
K. Miyata, D. Takahashi, R. Tamura, Org. Lett. 2011,13, 490– 499.
[39] X. Xu, X. Zhao, L. Sun, X. Liu, J. Nat. Gas Chem. 2009,18, 167 –
178.
[40] A. Djelad, A. Morsli, M. Robitzer, A. Bengueddach, F. Renzo, F.
Quignard, Molecules 2016,21, 109–116.
[41] Y. Mao, Y. Zhou, H. Wen, J. Xie, W. Zhang, J. Wang, New J. Chem.
2014,38, 3295–3301.
[42] M. R. Hudson, W. L. Queen, J. A. Mason, D. W. Fickel, R. F. Lobo,
C. M. Brown, J. Am. Chem. Soc. 2012,134, 1970 – 1973.
[43] O. Cheung, Q. Liu, Z. Bacsik, N. Hedin, Microporous Mesoporous
Mater. 2012,156, 90– 96.
[44] P. J. E. Harlick, F. H. Tezel, Microporous Mesoporous Mater. 2004,
76, 71–79.
[45] L. Grajciar, J. Ceijka, A. Zukal, C. O. Arean, G. T. Palomino, P.
Nachtigall, ChemSusChem 2012,5, 2011 – 2022.
[46] V. Ranjani Siriwardane, W. R. Stevens, (US Energy), US8128735
B1, 2012.
[47] M. H. Kim, H. Cho, J. H. Park, S. Choi, I.-S. Lee, J. Porous Mater.
2016,23, 291–299.
[48] W. Shao, L. Zhang, L. Li, R. L. Lee, Adsorption 2009,15, 497 – 505.
[49] S. Cavenati, C. A. Grande, A. E. Rodrigues, J. Chem. Eng. Data
2004,49, 1095–1103.
[50] K. S. Walton, M. B. Abney, M. D. LeVan, Microporous Mesoporous
Mater. 2006,91, 78– 84.
[51] Q. Liu, A. Mace, Z. Bacsik, J. Sun, A. Laaksonen, N. Hedin, Chem.
Commun. 2010,46, 4502– 4504.
[52] G. Maurin, P. L. Llewellyn, R. G. Bell, J. Phys. Chem. B 2005,109,
16084– 16091.
[53] J. S. Lee, J.-H. Kim, J.-T. Kim, J.-K. Suh, J.-M. Lee, C. H. Lee, J.
Chem. Eng. Data 2002,47, 1237– 1244.
[54] D. Bonenfant, L. Kharoune, S. Sauve, R. Hausler, P. Niquette, M.
Mimeault, M. Kharoune, Int. J. Greenhouse Gas Control 2009,3,
20–31.
[55] F. Su, C. Lu, S. C. Kuo, W. Zeng, Energy Fuels 2010,24, 1441–1448.
[56] W. Insuwan, K. Rangsriwatananon, Eng. J. 2012,16, 1–12.
[57] D. Shakarova, A. Ojuva, L. Bergstrçm, F. Akhtar, Mater. 2014,7,
5507–5519.
[58] S. Huh, J. W. Wiench, J.-C. Yoo, M. Pruski, S.-Y. Lin, Chem. Mater.
2003,15, 4247–4256.
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
16
&
These are not the final page numbers! ÞÞ

[59] R. M. Barrer, Zeolites and Clay Minerals as Sorbents and Molecular
Sieves, Academic, London, 1978, pp. 366– 371.
[60] D. M. Ruthven, Principles of Adsorption and Adsorption Processes,
2nd ed., Wiley, New York, 1984, pp. 433 –439.
[61] R Sabouni, Carbon Dioxide Adsorption By Metal Organic Frame-
works (Synthesis Testing and Modeling), PhD Thesis, University of
Western Ontario, London, ON, Canada, 2013, pp. 203– 211.
[62] M. Younas, M. Sohail, L. L. Knog, M. J. K. Bashir, S. Sethupathi,
Int. J. Environ. Sci. Technol. 2016,13, 1839– 1860.
[63] Y. Chen, Z. Li, Q. Liu, Y. Shen, X. Wu, D. Xu, X. Ma, L. Wang, H.
Chen, Z. Zhang, S. Xiang, Cryst. Growth Des. 2015,15, 3847– 3852.
[64] Z. Zhang, Z. Yao, S. Xiang, C. Banglin, Energy Environ. Sci. 2014,
7, 2868–2899.
[65] L. Liu, Y. Ye, Z. Yao, L. Zhang, Z. Li, L. Wang, X. Ma, Q.-H.
Chen, Z. Zhang, S. Xiang, Chin. J. Chem. 2016,34, 215–219.
[66] Z. Yao, Y. Chen, L. Liu, X. Wu, S. Xiong, Z. Zhang, S. Xiang,
ChemPlusChem 2016,81, 850-856, DOI: 10.1002/cplu.201600156.
[67] R. R. Willis, A. I. Benin, J. J. Low, R. Bedard, D. Lesch, Annual
Report, Project DE-FG26-04NT42121, National Energy Technology
Laboratory, 2006, pp. 201– 209.
[68] R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa, M.
OKeeffe, O. M. Yaghi, Science 2008,319, 939–947.
[69] N. Stock, Microporous Mesoporous Mater. 2010,129, 287– 297.
[70] J.-R. Li, Y. Ma, M. C. McCarthy, J. Sculley, J. Yu, H.-K. Jeong, P. B.
Balbuena, H.-C. Zhou, Coord. Chem. Rev. 2011,255, 1791– 1800.
[71] V. Colombo, S. Galli, H. J. Choi, G. D. Han, A. Maspero, G. Palm-
isano, N. Masciocchi, J. R. Long, Chem. Sci. 2011,2, 1311 –1319.
[72] A. M. Fracaroli, H. Furukawa, M. Suzuki, M. Dodd, S. Okajima, F.
Gandara, J. A. Reimer, O. M. Yaghi, J. Am. Chem. Soc. 2014,136,
8863–8866.
[73] D. Britt, H. Furukawa, B. Wang, T. G. Glover, O. M. Yaghi, Proc.
Natl. Acad. Sci. USA 2009,106, 20637 – 20643.
[74] H. Furukawa, N. Ko, Y. B. Go, N. Aratani, S. B. Choi, E. Choi,
A. O. Yazaydin, R. Q. Snurr, M. OKeeffe, J. Kim, O. M. Yaghi, Sci-
ence 2010,329, 424– 431.
[75] L. Wang, H. Deng, H. Furukawa, F. Gndara, K. E. Cordova, D.
Peri, O. M. Yaghi, Inorg. Chem. 2014,53, 5881 – 5883.
[76] P. D. C. Dietzel, R. E. Johnsen, H. Fjellvg, S. Bordiga, E. Groppo,
S. Chavan, R. Blom, Chem. Commun. 2008, 5125–5134.
[77] N C. Burtch, H. Jasuja, S. K. Walton, Chem. Rev. 2014,114, 10575 –
10612.
[78] A. C. Kizzie, A. G. Wong-Foy, A. J. Matzger, Langmuir 2011,27,
6368–6374.
[79] J. Rabone, Y. F. Yue, S. Y. Chong, K. C. Stylianou, J. Bacsa, D. Brad-
shaw, G. R. Darling, N. G. Berry, Y. Z. Khimyak, A. Y. Ganin, P.
Wiper, J. B. Claridge, M. J. Rosseinsky, Science 2010,329, 1053–
1067.
[80] Q. Wang, J. Bai, Z. Lu, Y. Pan, X. You, Chem. Commun. 2016,52,
443–452.
[81] B. Li, Z. Zhang, Y. Li, K. Yao, Y. Zhu, Z. Deng, F. Yang, X. Zhou,
G. Li, H. Wu, N. Nijem, Y. Chabal, Z. Lai, Z. Shi, S. Feng, J. Li,
Angew. Chem. Int. Ed. 2012,51, 1412–1421; Angew. Chem. 2012,
124, 1441– 1444.
[82] H. Wu, R. S. Reali, D. A. Smith, M. C. Trachtenberg, J. Li, Chem.
Eur. J. 2010,16, 13951– 13961.
[83] H. S. Choi, M. P. Suh, Angew. Chem. Int. Ed. 2009,48, 6865 – 6869 ;
Angew. Chem. 2009,121, 6997–7101.
[84] B. Zheng, Z. Yang, J. Bai, Y. Li, S. Li, Chem. Commun. 2012,48,
7025–7037.
[85] E. Dooris, C. A. McAnally, E. J. Cussen, A. R. Kennedy, A. J.
Fletcher, Crystals 2016,6, 14–25.
[86] J. Zhang, L. Sun, F. Xu, F. Li, H. Y. Zhou, Y. L. Liu, Chem.
Commun. 2012,48, 759– 768.
[87] W. Lu, D. Yuan, T. A. Makal, J. R. Li, H. C. Zhou, Angew. Chem.
Int. Ed. 2012,51, 1580–1595; Angew. Chem. 2012,124, 1612–1616.
[88] Z. J. Lin, Z. Yang, T. F. Liu, Y. B. Huang, R. Cao, Inorg. Chem.
2012,51, 1813–1822.
[89] D. Zacher, O. Shekhah, C. Woll, R. A. Fischer, Chem. Soc. Rev.
2009,38, 1418–1426.
[90] M. Eddaoudi, F. Sava, J. F. Eubank, K. Adil, V. Guillerm, Chem.
Soc. Rev. 2015,44, 228– 234.
[91] S. Keskin, D. S. Sholl, Ind. Eng. Chem. Res. 2009,48, 914– 921.
[92] S. Keskin, D. S. Sholl, Langmuir 2009,25, 11786–11796.
[93] E. Atci, I. Erucar, S. J. Keskin, Phys. Chem. C 2011,115, 6833–
6842.
[94] S. J. Keskin, Phys. Chem. C 2011,115, 800–812.
[95] R. Krishna, J. M. Van Baten, Phys. Chem. Chem. Phys. 2011,13,
10593– 10599.
[96] V. V. Guerrero, Y. Yoo, M. C. McCarthy, H. K. Jeong, J. Mater.
Chem. 2010,20, 3938– 3943.
[97] S. Takamizawa, Y. Takasaki, R. Miyake, J. Am. Chem. Soc. 2010,
132, 2862– 2874.
[98] Y. Yoo, Z. P. Lai, H. K. Jeong, Microporous Mesoporous Mater.
2009,123, 100–112.
[99] Y. Y. Liu, Z. F. Ng, E. A. Khan, H. K. Jeong, C. B. Ching, Z. P. Lai,
Microporous Mesoporous Mater. 2009,118, 296– 303.
[100] Y. S. Li, F. Y. Liang, H. Bux, A. Feldhoff, W. S. Yang, J. Caro,
Angew. Chem. Int. Ed. 2010,49, 548–554; Angew. Chem. 2010,122,
558–561.
[101] Y. S. Li, F. Y. Liang, H. G. Bux, W. S. Yang, J. Caro, J. Membr. Sci.
2010,354, 48–58.
[102] H. Bux, F. Y. Liang, Y. S. Li, J. Cravillon, M. Wiebcke, J. Caro, J.
Am. Chem. Soc. 2009,131, 16000 – 16012.
[103] M. C. McCarthy, V. Varela-Guerrero, G. V. Barnett, H.-K. Jeong,
Langmuir 2010,26, 14636– 14645.
[104] Y. Liu, E. Hu, E. A. Khan, Z. Lai, J. Membr. Sci. 2010,353, 36 – 40.
[105] A. Huang, H. Bux, F. Steinbach, J. Caro, Angew. Chem. Int. Ed.
2010,49, 4958–4965; Angew. Chem. 2010,122, 5078–5081.
[106] Y. Hu, X. Dong, J. Nan, W. Jin, N. Xu, Y. M. Lee, Chem. Commun.
2011,47, 737–743.
[107] D.-S. Zhang, Z. Chang, Y.-F. Li, Z.-Y. Jiang, Z.-H. Xuan, Y.-H.
Zhang, J.-R. Li, Q. Chen, T.-L. Hu, X.-H. Bu, Sci. Rep. 2013,3,
3312–3319.
[108] S. J. D. Smith, B. P. Ladewig, A. J. Hill, C. H. Lau, M. R. Hill, Sci.
Rep. 2015,5, 7823– 7832.
[109] Y. Shen, Z. Li, L. Wang, Y. Ye, Q. Liu, X. Ma, Q. Chen, Z. Zhang,
S. Xiang, J. Mater. Chem. A 2015,3, 593 –599.
[110] Y. Ye, S. Xiong, X. Wu, L. Zhang, Z. Li, L. Wang, X. Ma, Q.-H.
Chen, Z. Zhang, S. Xiang, Inorg. Chem. 2016,55, 292 – 299.
Received: June 9, 2016
Revised: July 10, 2016
Published online on &&
&&
, 0000
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
17
&
These are not the final page numbers! ÞÞ

REVIEWS
M. Abu Ghalia, Y. Dahman*
&& –&&
Development and Evaluation of
Zeolites and Metal–Organic
Frameworks for Carbon Dioxide
Separation and Capture
Capture and release: The selective ad-
sorption of CO2over CH4and N2for
zeolites and metal–organic frameworks
(MOFs) depends on several aspects.
Studying the properties of a CO2ad-
sorbent and the relationship between
the physisorption properties and the
capacity for chemisorption is necessary
for the design of zeolites and MOFs as
efficient CO2sorbents.
Energy Technol. 2016,4, 1 – 18  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
18
&
These are not the final page numbers! ÞÞ