A molecular simulation study of CO 2 adsorption in metal-organic frameworks Pan YANG Master of Philosophy (Engineering) Supervisor: Dr Qinghua Zeng Co-Supervisor: Dr Kejun Dong School of Computing, Engineering and Mathematics Western Sydney University Sydney, Australia May 2018
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A molecular simulation study of CO2 adsorption in
metal-organic frameworks
Pan YANG
Master of Philosophy (Engineering)
Supervisor: Dr Qinghua Zeng
Co-Supervisor: Dr Kejun Dong
School of Computing, Engineering and Mathematics
Western Sydney University
Sydney, Australia
May 2018
ii
ACKNOWLEDGEMENTS
I would like to thank my principal supervisor Dr Qinghua Zeng for offering me the
opportunity to do the molecular dynamics research on metal-organic frameworks. I really
appreciate his patience, enthusiasm, encouragement and broad knowledge. I was
continuously advised and supported by his guidance in all the time of research timeframe and
writing of this thesis.
I am also grateful for the comments and feedbacks given by my co-supervisor Dr Kejun
Dong during my 2-year research period and my thesis writing.
Also, I appreciate many friends and visiting scholars for their insightful views and valuable
suggestions.
Lastly, thanks to the research service team of SCEM and HDR, Western Sydney University
for organising conferences and providing administrative and technical support.
iii
ABSTRACT
The increasing carbon dioxide density in the atmosphere has led to the global warming and
other environmental issues. Such increase in carbon dioxide comes mainly from the
combustion of thousands of tons of fossil fuels (coal, oil and natural gas). Thus, the
development of novel materials for CO2 capture, separation and sequestration is becoming
critically essential. Many materials including aqueous amine solvent, micro and mesoporous
solid substances have been extensively investigated for CO2 absorption/adsorption. It is found
that quite a lot of distinct metal-organic frameworks (MOFs) have remarkable CO2
adsorption capacity in room temperature, particularly HKUST-1 and MIL-68(In). HKUST-1
(Hong Kong University of Science and Technology) is a MOF made up of copper nodes with
1,3,5-benzenetricarboxylic acid struts between them. MIL-68(In) is an indium-based MOF
made up of the chains of InO4(OH)2 octahedral units which are interconnected with
terephthalate ligands to form central triangle and hexagon channels. To understand the micro-
mechanisms and hence to further improve their adsorption capacities, grand canonical Monte
Carlo and molecular dynamics simulations have been employed in this study to explore CO2
adsorption uptake. The results show that both fluorinated HKUST-1 and MIL-68(In) have a
superior CO2 adsorption performance than their unmodified structures. In addition, radial
distribution function and mean square displacement analysis methods have been carried out
to explore the CO2 adsorption sites and the self-diffusion within MOFs. The results indicate
that CO2 molecules in HKUST-1 are more likely to attach to the metal sites with the pressure
increase, however, the adsorbed CO2 in HKUST-1F and MIL-68F (In) are bound firmly to
fluoride atoms, reducing their mobility.
Keywords: HKUST-1, MIL-68(In), fluorination, CO2 adsorption, diffusion, molecular
dynamics simulation
iv
LIST OF FIGURES
Figure 1. Brief concept of carbon dioxide capture and storage/sequestration (CCS) (Lee &
Park 2015). ................................................................................................................................. 5
Figure 2. General reaction mechanisms for the chemical absorption of CO2 in amine-based
Figure 6. Schematic diagram of a basic MD code(Zeng, Yu & Lu 2010).
3.6 Molecular dynamics analysis methods
Very recently, MD simulation has been extensively deployed to explore and determine the
diffusion and dynamic properties including self-diffusivity, transport diffusivity and corrected
diffusivity of CO2 in MOFs. The majority of the studies of molecules diffusion are obtained
22
by single MD or an experimental combined MD method (Atci, Erucar & Keskin 2011;
Krishna & Van Baten 2006; Li, J-R, Kuppler & Zhou 2009; Parkes et al. 2014; Salles,
Fabrice et al. 2013; Skoulidas & Sholl 2005).
3.6.1 Mean square displacement
Mean square displacement (MSD) analysis is a technique which is critical in characterizing
the diffusion behavior of adsorbed molecules in the system. It determines the particles
average displacement in a molecular dynamics simulation as shown in Figure 7 (Kärger
1992). In addition, self-diffusion constant (Ds) can be obtained by using the Einstein relation
which is take the slope of MSD over time (Chandler 1975; Michalet 2010).
Figure 7. Mean square displacement.
3.6.2 Radial distribution function
Besides, MD simulation provides a direct image to examine particles’ packing or ordering
probability in the system by the radial distribution function (RDF) analysis. RDF is a pair
correlation function which describes how atoms or particles in a system are radically packed
around each other(Nijboer & Van Hove 1952). It could provide an effective way to describe
0
50
100
150
200
250
300
0 100 200 300 400 500
Mea
n S
qu
are
Dis
pla
cem
ent
(Ds)
Time(Ps)
Pressure 0.1bar
23
the overall structure properties of disordered molecular systems as shown in Figure
8(Waisman 1973). RDF can be expressed by the following equation (Eq 5)
𝑔(𝑟) = 𝑛(𝑟)/(𝜌4𝜋𝑟2d𝑟) (5)
Where 𝑔(𝑟) is the RDF; 𝑛(𝑟) is the mean number of atoms in a shell of width d𝑟 at
distance 𝑟, 𝜌 is the mean atom density.
Moreover, the RDF results could provide a fine supplement with X-ray or neutron diffraction
(Bentley et al. 1990; Filipponi 1994; Li, F & Lannin 1990). Thus, the binding sites of CO2
molecules can be explored by RDF method after MD simulation.
Figure 8. Radial distribution function.
3.6.3 Adsorption strength
In addition, the adsorption energy (Ep) between MOFs and CO2 is quite difficult to assess
both experimentally and numerically. However, it may be achieved in MD simulation by
calculating the average value of CO2 adsorbed MOFs equilibrium frames, i.e. 6 frames from
relatively stable 400 to 500 ps. Thus, the adsorption energy (Ep) could be calculated by the
Eq 6,
24
Ep=Etotal-EMOF-ECO2 (6)
Where Etotal, EMOF and ECO2 are the energy of CO2 adsorbed MOF extracted MOF and
extracted CO2 molecules, respectively, as shown in Figure 9. By exacting the CO2 adsorbed
MOFs equilibrium frames, the total potential energy Etotal can be calculated by the Forcite in
Materials Studio. After removing the all of the adsorbed CO2 in the structure, we are able to
achieve the potential energy of the MOF at the equilibrium stage. We can also accomplish the
potential energy calculation of the CO2 molecules by deleting the MOF structure in the
frame, thus, the interaction strength (adsorption energy) could be measured by the Eq 6 to
understand the adsorption strength between CO2 and MOF under specific pressure.
Figure 9. The snapshot of a CO2 adsorbed equilibrium MOF structure: CO2 adsorbed
MOF (upper), isolated MOF (lower left) and isolated adsorbed CO2 molecules (lower
right).
25
3.7 Summary
To summarize, this section highlights the main research approaches including the GCMC and
MD simulations. Prior to the simulations, the input parameters such as atomic partial charges
and force field are important which should be defined appropriately. With the intermolecular
and intramolecular interactions are appropriately described by the force fields, the grand
canonical Monte Carlo (GCMC) simulation is often implemented to predict the gas
adsorption capacity in a periodic simulation box ,in which the temperature T, the volume V
and chemical potentials are kept constant, only the number of adsorbed molecules N are
allowed to fluctuate by randomly creating, rotating , deleting as well as translating/displacing
in the system, and then the average amount of adsorbed molecules is statistically calculated
when the system reached equilibrium stage. At the moment, GCMC simulation is a practical
and popular computational technique to investigate the adsorption properties of single
component CO2 or mixtures in MOFs. Moreover, MD simulation, based on the Newton’s
equitation of motion, is becoming increasingly popular to investigate the kinetic and transport
properties of the adsorbate in microporous materials, especially in MOFs. The RDF and
MSD analysis method will be adopted to explore the CO2 binding locations and its self-
diffusion within MOFs. Lastly, the energy strength between CO2 and MOFs is calculated to
reveal the related relationship.
26
CHAPTER 4 CARBON DIOXIDE ADSORPTION IN HKUST-1
4.1 Model configuration
HKUST-1, also known as Cu-BTC, is one of the most extensively investigated MOFs for gas
adsorption and separation after it was first synthesized by Chui and co-workers in 1999(Chui
et al. 1999).
The model of HKSUT-1 is employed from the Crystallography Open Database
(No.2300380). This structure of HKUST-1 was reported by Yakevenko and co-workers in
2013 (Yakovenko et al. 2013).
HKUST-1 consists of paddlewheel-coordinated copper clusters and surrounded by 1, 3, 5-
benzenetricarboxylate (BTC) organic linkers. Each metal node is composed of two copper
atoms connected to the oxygens of four BTC ligands (see Figure 10a). In order to construct
the fluorinated model (HKUST-1F), all of the hydrogen atoms on BTC organic linkers are
manually replaced by fluoride elements (Figure 10b) by using the module of Materials Studio
Visualizer.
(a)
27
(b)
Figure 10 Unit cells of HKUST-1 (a) and HKUST-1F (b), Colour: Copper in orange,
oxygens in red, carbons in grey, hydrogen in white and fluorides are light blue.
4.2 Grand Canonical Monte Carlo Simulation details
As described above, the atomic partial charges and force field are critical for molecular
simulations. For this reason, all of the charges of HKSUT-1 and HKUST-1F were initially
reset to be zero, and then the atomic partial charges in frameworks were obtained by QEq
method (see the details in Table 1), and maintained in the following simulations.
Prior to the GCMC simulation, the energy calculation and geometry optimization were
applied on MOFs in order to obtain an optimal configuration. The force field of UFF was
performed on HKUST-1 and HKUST-1F, Ewald technique was utilized to calculate the
electrostatic interactions. Atom based method with a cut-off distance of 15.5 Å was used in
the calculations of van der Waals (vdW) interactions.
Given the quadrupole movement of carbon dioxide, CO2 was modelled as a linear molecule
with double C=O, and the atomic partial charge of O and C atom was calculated by QEq
method which were -0.446e and 0.892e, respectively, when implemented the energy and
geometry optimization on CO2, the UFF was determined and Atom based method was used
for both vdW interactions electrostatic interactions calculation.
28
Table 1. The Atomic partial charge q (e) and force field of HKUST-1 and HKUST-1F.
Element
Atomic partial
charge
Force field type Hybridization
Cu 2.388
Cu3+1
Trigonal-bipyramid
O -0.702
O_3
Trigonal
H 0.052
H_
No hybridization
Cu* 3.001
Cu3+1
Trigonal-bipyramid
O* -0.715
O_3
Trigonal
F* -0.8 F_ No hybridization
* is the element in HKUST-1F
Unlike the most simulation studies on HKUST-1 published before to keep the MOFs and CO2
as rigid, in present work, the MOFs and CO2 are allowed to be flexible during the GCMC
simulations. The periodic boundary condition was applied. For HKUST-1, since the cell
parameters were a=b=c=26.3 Å. we employed the unit cell as the simulation box, GCMC
method was defined as normal Metropolis technique, the adsorption isotherms of HKUST-1
and the HKUST-1F were performed at 298 K by Sorption modules in Materials Studio with
the pressure from 0.1 to 5 bars, and equilibration process of 1 × 106
steps followed by 1 × 107
production process steps with a cut-off radius of 18.5 Å. The Ewald technique was used to
handle the electrostatic interactions.
4.2.1 Adsorption isotherms of CO2 in HKUST-1 and HKUST-1F
The GCMC adsorption isotherm is a significant feature to access MOF’s property and
performance. Adsorption isotherms of CO2 in HKUST-1 and HKUST-1F are shown in Figure
11, which demonstrate that the adsorption capacity of HKUST-1F is much higher than that of
non-fluorinated HKUST-1. For example, the adsorbed CO2 in HKUST-1F unit cell is 176 at
0.1 bar compared with 62 in HKUST-1unit cell. At 1 bar, HKUST-1F adsorbs 194 carbon
dioxide molecules, which is almost the double of the HKUST-1. In addition, the uptake of
CO2 in HKUST-1 increases significantly with the pressure from 62 at 0.1 bar to 136 at 5 bars.
29
Yet, HKUST-1F reaches the saturated adsorption equilibrium at a relatively low pressure
(approximately between 0.5-1bar).
Figure 11. Adsorption isotherm of CO2 in HKUST-1 and HKUST-1F at 298K under
the pressure of from 0.1 to 5bar.
4.2.2 Comparison of CO2 adsorption isotherms of CO2 in
HKUST-1
The comparison of CO2 adsorption isotherms in HKUST-1 under different conditions
(experiment and simulation) are shown in Table 2. The results show that both HKUST-1 and
HKUST-1F in this work have a superior adsorption capacity. In particular, fluorinated
HKUST-1 has a much higher uptake than that of non-fluorinated structure, which may be
attributed to the strong electrostatic interactions between fluoride and CO2.
Table 2. CO2 adsorption capacity on HKUST-1(Cu-BTC) under different conditions.
MOFs Pressure (Bar) Temperature (K) Adsorption
capacity (mmol/g)
Adsorption
capacity (wt %)
HKUST-1
1 298
10.5
46.3
HKUST-1
5 298
14
61.7
HKUST-1F
1 298
17.2
75.5
30
MOFs Pressure (Bar) Temperature (K) Adsorption
capacity (mmol/g)
Adsorption
capacity (wt %)
HKUST-1F
5 298
17.3
76.3
HKUST-1a
HKUST-1b
10
15
327
298
7.19
12.7
31.6
-
HKUST-1c
(Ethanol+NH4Cl)
1 273
11.6
51
Cu-BTCd 10 298 11.9 52.4
a (Ye et al. 2013),b (Liang, Marshall & Chaffee 2009),c (Yan, X et al. 2014), (Zhao et al.
2011).
4.3 Molecular dynamics simulation results
4.3.1 Adsorption sites of CO2 in HKUST-1 and HKUST-1F
The MD simulation not only gives an adsorption prediction of CO2 in MOFs but also provide
an image of CO2 probability in MOFs, as shown in Figure 12 and 13 for HKUST-1 and
HKUST-1F. The results indicate that adsorbed CO2 in HKUST-1 at low pressure (1bar) are
more close to paddle-wheel-coordinated Cu sites, and the additional adsorbed CO2 are more
likely to appear at the central channel at high pressure (5 bar). For HKUST-1F, there is no
remarkable change for CO2 adsorbed in MOF from low to high pressure.
Figure 12. The CO2 (red spots) adsorption snapshot in HKUST-1, 1 bar (left) and 5
bar (right).
31
Figure 13. The CO2 (red spots) adsorption snapshot in HKUST-1F, 0.1 bar (left) and 5
bar (right).
In order to verify the more accurate and precise binding sites of CO2 in MOFs, radial
distribution function is implemented for analysis after MD simulation. The peaks indicate the
most possible locations of an atom from the reference atom at a specific radius. In present
study, RDF results of HKUST-1 and CO2 under different pressures are shown in Figure 14.
Due to the distinct orientations of oxygen atoms in CO2 molecule, the central carbon atom
was selected to represent the entire CO2, thus the atomic pairs are determined to be Cu
(MOF)-C (CO2), O (MOF) - C (CO2), and H (MOF) - C (CO2).
Figure 14a displays the shortest distance (first peak) is around 2.91 Å between H of HKUST-
1 and C of CO2, revealing the orientation of CO2 with C atoms toward H atoms of HKUST-1.
The next peak is located at 3.49 Å for O atoms of HKUST-1 and C atoms of CO2, followed
by a sharp and narrow peak at 3.93 Å for Cu atoms of HKUST-1 and C atoms of CO2. We
could predict that the CO2 molecules are more close to H atom (BTC linker) of HKSUT-1 at
the pressure of 0.1 bar.
With the pressure rise (Figure 14b, 3c, 3d and 3e), we found that the first peak of Cu- C pair
is still situated at around 3.9 Å, and the peak of the O-C pair is at about 3.49 Å. However, the
peak of H-C pair becomes flat and broad, indicating majority of additional CO2 adsorbed
move toward Cu sites, which may be attributed by the open metal site effect.
32
33
34
Figure 14. Radial distribution function of atomic pairs from HKUST-1 and CO2 at
298 K and different pressure: (a) 0.1 bar, (b) 0.5 bar, (c) 1 bar (d) 3 bar and (e) 5 bar,
respectively.
Similar RDF analyses are shown for HKUST-1F in Figure 15. The atomic pairs are Cu
(MOF)-C (CO2), O (MOF)-C (CO2) and F-C (CO2). RDF results of HKUST-1F indicate that
there is a stronger interaction is between F atoms in MOF and the C atoms of CO2, reflected
from the drastic and sharp first peak at 2.75 Å. The peaks are located at the same distance
with the pressure rising to 5 bar, but peaks are becoming slightly wide for F-C atomic pair,
demonstrating CO2 molecules are bound tightly to F atoms. The peak of Cu-C atomic pair has
a slight decrease due to the amount of the carbon dioxide adsorbed increases and CO2 are
more close to F sites.
35
36
37
Figure 15. Radial distribution function of atomic pairs from HKUST-1F and CO2 at
298 K and different pressure: (a) 0.1 bar, (b) 0.5 bar, (c) 1 bar (d) 3 bar and (e) 5 bar,
respectively.
4.3.2 Self-diffusivity of CO2 in HKUST-1 and HKUST-1F
To further probe the diffusion property of adsorbed CO2 in MOFs, the mean square
displacement (MSD) method has been performed to probe the diffusivity of CO2 in MOFs.
We take advantage of the carbon atom representing the CO2 as an approximation. Figure 16
shows the self-diffusivity of CO2 in HKUST-1 and HKUST-1F by taking the slope of the
MSD curves over time from 0 to 400 ps. The results indicate the self-diffusion of CO2
molecules in HKUST-1 and HKUST-1F declines with pressure increase. This is an expected
result and can be explained by the increase in adsorbed CO2 and then the steric hindrance of
movement for adsorbed CO2 molecules within MOFs’ structures. Note that the diffusivity
(MSD slope) of CO2 in HKUST-1F is much lower than that of non-fluorinated HKUST-1,
suggesting adsorbed CO2 is attached firmly.
38
Figure 16. Mean square displacement over time of CO2 in HKUST-1and HKUST-1F.
4.3.3 Interaction strength between CO2 and HKUST-1
In order to obtain insight of the interaction strength between CO2 and MOFs, we extracted the
structures of MOFs and adsorbed CO2 molecules, respectively, and then calculated the
interaction energy (Ep). The results as shown in Table 3 and Table 4 indicate that interaction
strength between MOFs and CO2 increases with pressure (i.e. CO2 loading). Moreover, the
interaction is attractive in nature of CO2 due to the negative potential energy. The Ep of
HKUST-1F is higher than HKUST-1, reflected to the increased loading number of CO2
(adsorption capacity). The potential energy of extracted CO2 in HKUST-1 reduced
significantly from positive (repulsion) to negative (attraction), suggesting the distance
between CO2 increases (i.e. loosely adsorbed). For HKUST-1F, potential energy of CO2 is
relatively low, which indicates CO2 molecules are stable and could hardly move.
39
Table 3. Interaction potential energies (Kcal/mol) of CO2 adsorbed in HKUST-1.
Pressure(bar)
Loading(number
per cell)
Total
Energy
Energy of MOF Energy of CO2 Ep
0.1 62
7974.9
8505.1
49.1
-579.3
0.5 83
7863.9
8527.5
36.4 -700
1 99
7739.7
8520.3
13.8 -794.3
3 126
7557.9
8519.9
-29.1 -932.9
5 136
7488
8520.9
-54.2 -978.7
Table 4. Interaction potential energies (Kcal/mol) of CO2 adsorbed in HKUST-1F.
Pressure(bar)
Loading(number
per cell)
Total
Energy
Energy of MOF Energy of CO2 Ep
0.1 176
-1469.3
919
7.94
-2396.6
0.5 189
-1526.5
956.3
3.1 -2486
1 194
-1538.6
975.2
2.13 -2515.9
3 195
-1558.6
961.9
2.08 -2522.9
5 198
-1549.2
994.9
2.09 -2546.3
4.4 Summary
In summary, results of the GCMC simulation demonstrate that HKUST-1 and HKUST-1F in
this study have an exceptional CO2 adsorption capacity up to 5bar. And the fluoride modified
HKUST-1 has a higher uptake than that of non-fluorinated structure. The powerful
electrostatic interactions between fluoride and CO2 contribute to the superior gas uptake. MD
simulation has been performed to investigate the CO2 adsorption location and binding
strength in HKUST-1 and HKUST-1F. The results demonstrate that HKUST-1F has a
superior adsorption capacity for CO2, particularly at low pressure. Moreover, adsorbed CO2
molecules are bound closely to fluoride atoms of BTC organic linkers in HKUST-1F,
however, may hinder their diffusion to copper metal sites.
40
CHAPTER 5 CARBON DIOXIDE ADSORPTION IN MIL-68(In)
5.1 Model configuration
MIL-n(M) materials, Materials of Institute Lavoisier, are mainly connected with trivalent
metal cations M3+
(e.g. Al3+
, Cr3+
, Fe3+
, V3+
, Ga3+
or In3+
) and organic linkers of benzene
dicarboxylic acid which could form three-dimensional networks such as MIL-53(M), MIL-
68(M), and MIL-101(M), etc. Interestingly, MIL-53(M) and MIL-68(M) have the same
formula, same inorganic and organic units but show different framework features and
properties. MIL-53 series have been widely investigated for gas adsorption due to its unique
structure flexibility (Bourrelly et al. 2005; Hamon, Lomig et al. 2009; Lebedev et al. 2005;
Millange et al. 2008). The model of MIL-68(In) is adopted from the Crystallography Open
Database (No.4306785). MIL-68(In) is an Indium based metal-organic frameworks. The
MIL-68(In) is constructed with the chains of InO4 (OH) 2 octahedral units and interconnected
with the terephthalate ligands to form central triangle and hexagon channels (see Figure 17a).
In order to build up the fluorinated model which is MIL-68F (In), we utilized the Materials
Visualizer to do the modification, i.e. hydrogen atoms on terephthalate linkers are all
manually replaced by fluoride elements (Figure 17b) .
(a)
(b)
41
Figure 17. Unit cells of MIL-68 (a) and MIL-68F (In) (b), Colour: Indium in dark red,
oxygens in red, carbons in grey, hydrogen in white and fluorides are light blue.
5.2 Grand Canonical Monte Carlo Simulation details
Similarly, the atomic partial charges of MIL-68(In) and MIL-68F (In) were obtained by QEq
method and the UFF force filed was assigned for both MOFs as shown in in Table 5, these
parameters remain constant in the following simulations.
Table 5. The Atomic partial charge q (e) and force field of MIL-68(In) and MIL-68F (In).
Element
Atomic partial
charge
Force field type Hybridization
In 2.289
In3+3
Octahedral
O -0.519
O_3
Tetrahedral
H 0.1
H_
No hybridization
In* 2.697
In3+3
Octahedral
O* -0.498
O_3
Tetrahedral
F* -0.554 F_ No hybridization
* is the element in MIL-68F (In)
42
The energy calculation and geometry optimization were implemented on MIL-68(In) and
MIL-68F (In) in order to seek an optative configuration for the following simulations. In
these calculations, Ewald technique was used to calculate the electrostatic interactions. Atom
based method with a cut-off distance of 15.5 Å was used in the calculations of van der Waals
(vdW) interactions.
Likewise, the CO2 molecule was modelled as a linear molecule with double C=O, and the
atomic partial charge of O and C atom were -0.446e and 0.892e which are the same as the
HKUST-1 project. UFF was selected and Atom based method was used for both vdW
interactions and electrostatic interactions calculation for energy and geometry optimization
on CO2.
In present work, the MIL-68(In), MIL-68F (In) and CO2 are allowed to be flexible during the
GCMC simulations. For HKUST-1, we employed a single unit cell as the simulation box;
however, in this case, the simulation box amplified to 3 (1×1×3) of unit cells because the
original cell parameters were a=21.73 Å, b=37.68 Å and c=7.23 Å, respectively. Likewise,
GCMC method was defined as normal Metropolis technique; the adsorption isotherms of
MIL-68(In) and the Mil-68F (In) were performed at 298 K by Sorption modules in Materials
Studio by the pressure from 0.1 to 5 bars, and equilibration process of 1 × 106 steps followed
by 1 × 107
production process steps with a cut-off distance of 15.5 Å which is smaller than of
HKUST-1(18.5 Å). Atom based method was used to calculate vdW interactions and the
Ewald technique was used to compute the Columbic interactions.
5.2.1 Adsorption isotherms of CO2 in MIL-68(In) and MIL-68F
(In)
Figure 18 shows the adsorption isotherms of CO2 in MIL-68(In) and MIL-68F (In), indicating
that the fluorinated MIL-68F (In) performs well than MIL-68(In) for CO2 uptake. For
instance, at pressure of 0.1 bar, only 6 CO2 molecules are adsorbed in the MIL-68(In) unit
cell, compared with 67 in the MIL-68 F (In). With the pressure increases to 1 bar, the number
of CO2 in MIL-68(In) grows to 23, while the number of CO2 adsorbed in MIL-68F (In) is 92.
After the pressure rise to 5 bars, the MIL-68(In) adsorption capacity escalates to 57 while the
MIL-68(In) F elevates to 117. Given the tendency of adsorption curves, both MIL-68(In) and
MIL-68 F (In) may not have reached to the adsorption equilibrium at 5 bars. It is expected
43
that MIL-68 and its fluorinated structures would have an advantageous CO2 adsorption
capacity at higher pressures.
Figure 18. Adsorption isotherm of CO2 in MIL-68(In) and MIL-68F (In) at 298K
under the pressure of from 0.1 to 5 bar.
5.2.2 Comparison of CO2 adsorption isotherms of CO2 in
HKUST-1 and MIL-68(In)
The previous experimental studies reported the CO2 adsorption capacities in MIL-68(In) and
MIL-68(In)-NH2 were 4 and 8 wt. % at 1 atm and 298 K, respectively(Arstad et al. 2008),
compared with present simulation results were 2.9 and 7.81 wt.% for MIL-68(In) and MIL-
68F (In) at 1 bar and 298 K, suggesting that the simulation result of MIL-68 is
underestimated, but the results for amine and fluoride functionalized MIL-68 are more close.
The results of the adsorption isotherms in MOFs, as shown is Figure 19, show that both
HKUST-1 and HKUST-1F have a relatively high adsorption capacity. In addition, fluorinated
MOFs, HKUST-1F and MIL-68 F (In) perform well for CO2 adsorption than that of non-
fluorinated structures, which may be attributed to the strong electrostatic interactions between
fluoride atoms and CO2. Note that the unit cell of MIL-68 is triple of original cells.
44
Figure 19. Comparison of CO2 adsorption isotherms of CO2 in HKUST-1 and MIL-
68(In).
5.3 Molecular dynamics simulation results
5.3.1 Adsorption sites of CO2 in MIL-68(In) and MIL-68F (In)
The adsorption sites images of CO2 in MIL-68 (In) and MIL-68F (In) of MD simulations are
displayed in Figures 20 and 21. It shows that adsorbed CO2 molecules in MIL-68(In) at 0.1
bar have great possibility arising in the central triangle pore, however, CO2 are more likely to
emerge at hexagon channel at 5 bar, while, the appearance probability of CO2 in MIL-68F
(In) varies insignificantly.
45
Figure 20. The CO2 (red spots) adsorption snapshot of MIL-68(In), 0.1 bar (left) and 5
bar (right).
Figure 21. The CO2 (red spots) adsorption snapshot of MIL-68F (In), 0.1 bar (left)
and 5 bar (right).
A series of RDF results of MIL-68 and CO2 under different pressures are shown in Figure 22.
The atomic pairs are In (MOF)-C (CO2), O (MOF) - C (CO2), and H (MOF) - C (CO2).
At pressure of 0.1 bar, as shown in Figure 22a, the relatively strongest interaction (first peak)
is between O in MOF and the C of CO2, as located at 3.41 Å, and closely followed by the
peak of H (MOF) - C (CO2), which is located at 3.61 Å. The peak of In–C pair is located 4.41
Å, revealed as a relatively intense and sharp peak. Thus, the adsorbed CO2 molecules are
bound closely to O and H atoms in MIL-68(In), which is the triangle pore of the structure.
46
With pressure increasing to 0.5 bar, as shows in Figure 22b, the first peak appears at 3.15 Å,
which is O-C pair, the next peak, H-C pair, is located at 3.85 Å, followed by a strong peak
of In-C pair, which is located at 4.79 Å, indicating that additional adsorbed CO2 at 0.5 bar
are more close to O atoms. When the pressure rises to 1 bar (see Figure 22c), the H-C and O-
C atomic pairs are becoming wide and fewer intense, while, the peak of In-C remains sharp,
probably suggesting that additional adsorbed CO2 molecules become to emerge in hexagon
void of MIL-68(In) structure. With the pressure continues to creep up to 3 and 5 bars, the
CO2 molecules are more close to the H atoms, however, they reside in a more widespread
area, and majority of molecules may probably be adsorbed in the hexagon area, revealed as
three broad peaks in the Figures 22d and 22e.
47
48
Figure 22. The radial distribution function for atomic pairs of MIL-68 and CO2 at 298
K and different pressure: (a) 0.1 bar, (b) 0.5 bar, (c) 1 bar (d) 3 bar and (e) 5 bar,
respectively.
49
In terms of MIL-68F (In), Figure 23 displays the RDF results of CO2 in this structure. The
atomic pairs are In (MOF)-C (CO2), O (MOF)-C (CO2) and F-C (CO2). The trend of these
curves is quite similar to that of HKUST-1F. The results demonstrate a forceful interaction
between F atoms of MOF and the C atoms of CO2, which corresponds to a drastic first peak
at 2.85 Å, and with the pressure rising to 5 bars; the radius of first peak which is F-C atomic
pair has no change. In addition, the G(r) of F-C peak reduces slightly because more CO2
molecules are binding closely to F atoms with the pressure increasing. The peaks of O-C and
In-C pairs are extensive and wide, indicating that CO2 are less likely to be bound with them.
50
51
Figure 23. Radial distribution function of atomic pairs from MIL-68F and CO2 at 298
K and different pressure: (a) 0.1 bar, (b) 0.5 bar, (c) 1 bar (d) 3 bar and (e) 5 bar,
respectively.
5.3.2 Self-diffusivity of CO2 in MIL-68(In) and MIL-68F (In)
Likewise, the MSD analysis technique was carried out to observe CO2 self-diffusivity in
MIL-68 (In) and MIL-68F (In), as shown in Figure 24.
Interestingly, MSD results unfold that self-diffusivity of CO2 in MIL-68F (In) is much lower,
demonstrating that CO2 are adsorbed strongly within the structure, which is quite similar to
HKUST-1F. For MIL-68(In), the diffusion of CO2 is slow at low pressure (0.1bar), with the
pressure increase to 1 bar, the diffusion of CO2 has a remarkable surge, and however, when
the pressure rise to 5 bar, the movement of CO2 molecules becomes difficult. Since the MIL-
n (M) materials have been extensively studied on their structure flexibility such as “gate-
opening” or “breathing” phenomenon, we may infer that the pore diameter in MIL-68 may
have a relatively significant increase at 1 bar, resulting in the high self-diffusivity coefficient
of CO2 molecules. However, we did not observe a noticeable rise in the GCMC adsorption
isotherm at 1 bar. Further analysis must be implemented to examine and probe on pore
diameters variation.
52
Figure 24. Mean squared displacement over time of CO2 in MIL-68(In) and MIL-68F
(In).
5.3.3 Interaction strength between CO2 and MIL-68(In)
Likewise, Tables 6 and 7 illustrate that interaction strength between MOFs and CO2 increases
with pressure/CO2 loading. The strength of fluorinated structure is much higher than non-
fluorinated one, corresponding to the uptake amount of CO2. Besides, the potential energy of
CO2 molecules in MIL-68 and MIL-68 (In) F increases notably from 0.1 to 3 bars,
demonstrating the average distance of adsorbed CO2 reduces, however, the CO2 potentials
decline with the pressure increasing to 5 bars, suggesting CO2 molecules are becoming loose
in the MOFs.
53
Table 6. Interaction potential energies (Kcal/mol) of CO2 adsorbed in MIL-68 (In).
Pressure(bar)
Loading(number
per cell)
Total
Energy
Energy of MOF Energy of CO2 Ep
0.1 6
-22305.1
-22258
5.72
-52.84
0.5 16
-22384.5
-22272.3
20.23 -132.41
1 23
-22442.4
-22230
34.85 -177.24
3 43
-22447.5
-22191.4
48.65 -304.77
5 57
-22378.8
-22022.5
32.89 -385.23
Table 7. Interaction potential energies (Kcal/mol) of CO2 adsorbed in MIL-68F (In).
Pressure(bar)
Loading(number
per cell)
Total
Energy
Energy of MOF Energy of CO2 Ep
0.1 67
-33261.6
-32664.4
-1.35
-595.86
0.5 84
-33256.3
-32623.7
34.95 -667.56
1 92
-33224.6
-32584
35.1 -695.78
3 107
-33074.7
-32394.8
67.31 -747.13
5 117
-2824.8
-32103.7
53.77 -774.85
5.4 Summary
In conclusion, the MD simulation results of MIL-68 (In) and its fluorinated structure reveal
that adsorption strength of MIL-68F (In) is much higher than the untreated MOF, which is in
line with the adsorption loading of GCMC results. In addition, the tight binding of CO2
molecules to fluoride functional organic ligands not only restricts the movement of the
molecules but also may have no effect on the structure flexibility of MIL-68 (In).
54
CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS
6.1 Conclusions
In this thesis, a hybrid GCMC and MD simulation method is adopted to explore the CO2
adsorption performances on two typical and distinct MOFs, HKUST-1 and MIL-68(In).
Previous studies have paid numerous attentions on the single predominant factor or effect
such as open metal site, structure flexibility and group functionalization. In addition, the
kinetic and transport properties of CO2 in MOFs are less studied either.
In present work, the intense literature surveys have been done to understand the experimental
and computational accomplishments of CO2 adsorption behaviour on HKUST-1 and MIL-
68(In). It is evident that there is few work on the fluorinated MOFs for CO2 capture and
adsorption, especially on HKUST-1 and MIL-68(In). Moreover, the study on CO2 diffusion
properties is also scant compared with the tremendous programmes on the adsorption
capacity. In order to investigate the performances of fluorinated HKUST-1 and MIL-68(In)
for CO2 capture. The fluoride modification of structures of HKUST-1 and MIL-68(In) are
carried out by Material Studio Visualizer.
With the atomic partial charges and the force fields (UFF) being assigned, the GCMC
simulation is employed to predict CO2 adsorption isotherms in MOFs. The MD simulation is
implemented to explore the CO2 adsorption sites in MOFs and the CO2 self-diffusion during
the adsorption process. Some major findings have been achieved: (I) the GCMC results
exhibit that the both fluorinated MOFs have a significant improved CO2 adsorption capacity
than that of non-fluorinated structures, indicating that the fluoride modification treatment is
favourable to enhance CO2 adsorption, particular the HKUST-1. (II) MD simulation results
including RDF and MSD measurement of HKUST-1F demonstrate the interaction between
fluoride and CO2 is dominant at the low pressure which will restrict the diffusion of CO2
molecules, however, may be negative for the CO2 adsorption at the high pressure or CO2
desorption for adsorbent regeneration. (III) In the case of MIL-68, although MIL-68 and its
fluorinated structure do not perform as well as HKUST-1 for CO2 adsorption under the
pressure of 5 bars, it is expected to increase at higher pressures according to the adsorption
isotherm tendency. Besides, the functional group (fluoride modification) may not be effective
for the structural “open-up” of MIL-68 as there is no obviously significant CO2 adsorption
increase from 0.1 to 5 bar.
55
6.2 Recommendations on future work
The further studies can be considered from this work; firstly, GCMC simulations can be
implemented up to 20-30 bars to examine the CO2 adsorption on MIL-68(In) and its
fluorinated structure to explore the adsorption increase at a specific threshold pressure.
Secondly, the various fluoride modification sites on the organic linkers could be exploited, in
this case, all of the H atoms have been replaced by fluoride, however, there are still many
replacement options to compromise and enhance the CO2 adsorption capacity and self-
diffusivity in MOFs. For example, the number of the fluoride modification can be one or two
on the organic ligands and operational location can be 1.3, 1.5 or 3.5. Thirdly, with regard to
the refinement of force filed, although UFF is a good approximation to describe the
interactions in many MOFs and in this work, it may not be accurate for fluorinated HKUST-
1and MIL-68F (In) owing to the intense electrostatic field generated by the fluoride atoms.
56
REFERENCES
Abanades, JC, Rubin, ES & Anthony, EJ 2004, 'Sorbent cost and performance in CO2 capture systems', Industrial & Engineering Chemistry Research, vol. 43, no. 13, pp. 3462-6. Achten, WMJ, Almeida, J & Muys, B 2013, 'Carbon footprint of science: More than flying', Ecological Indicators, vol. 34, pp. 352-5. Adams, DJ 1975, 'GRAND CANONICAL ENSEMBLE MONTE-CARLO FOR A LENNARD-JONES FLUID', Molecular physics, vol. 29, no. 1, pp. 307-11. AghaKouchak, A, Cheng, LY, Mazdiyasni, O & Farahmand, A 2014, 'Global warming and changes in risk of concurrent climate extremes: Insights from the 2014 California drought', Geophysical Research Letters, vol. 41, no. 24, pp. 8847-52. Akkermans, RL, Spenley, NA & Robertson, SH 2013, 'Monte Carlo methods in materials studio', Molecular Simulation, vol. 39, no. 14-15, pp. 1153-64. Alhamami, M, Doan, H & Cheng, C-H 2014, 'A Review on Breathing Behaviors of Metal-Organic-Frameworks (MOFs) for Gas Adsorption', Materials, vol. 7, no. 4, p. 3198. Andersen, HC 1980, 'Molecular dynamics simulations at constant pressure and/or temperature', The Journal of Chemical Physics, vol. 72, no. 4, pp. 2384-93. Arstad, B, Fjellvåg, H, Kongshaug, KO, Swang, O & Blom, R 2008, 'Amine functionalised metal organic frameworks (MOFs) as adsorbents for carbon dioxide', Adsorption, vol. 14, no. 6, pp. 755-62. Atci, E, Erucar, I & Keskin, S 2011, 'Adsorption and Transport of CH4, CO2, H-2 Mixtures in a Bio-MOF Material from Molecular Simulations', Journal of Physical Chemistry C, vol. 115, no. 14, pp. 6833-40. Azar, C, Lindgren, K, Obersteiner, M, Riahi, K, van Vuuren, DP, den Elzen, KMGJ, Möllersten, K & Larson, ED 2010, 'The feasibility of low CO2 concentration targets and the role of bio-energy with carbon capture and storage (BECCS)', Climatic Change, vol. 100, no. 1, pp. 195-202. Babarao, R & Jiang, J 2008, 'Molecular screening of metal− organic frameworks for CO2 storage', Langmuir, vol. 24, no. 12, pp. 6270-8. Bains, P, Psarras, P & Wilcox, J 2017, 'CO2 capture from the industry sector', Progress in energy and combustion science, vol. 63, pp. 146-72. Banerjee, R 2012, 'Functionalized Metal Organic Frameworks (MOFs) for reversible gas storage and sequestration applications', Journal of the Indian Chemical Society, vol. 89, no. 9, pp. 1197-202. Barcza, S 2017, 'Greenhouse effect from the point of view of radiative transfer', Acta Geodaetica Et Geophysica, vol. 52, no. 4, pp. 581-92. Benson, SM, Bennaceur, K, Cook, P, Davison, J, Coninck, Hd, Farhat, K, Ramirez, CA, Simbeck, D, Surles, T, Verma, P & Wright, I 2012, 'Carbon Capture and Storage', in Global Energy Assessment - Toward a Sustainable Future, Cambridge University Press, pp. 993 - null.
57
Bentley, J, Angelini, P, Gove, AP, Sklad, PS & Fisher, AT 1990, 'RADIAL-DISTRIBUTION FUNCTIONS OF AMORPHOUS MATERIALS FROM ONLINE MEASUREMENTS OF DIFFRACTED ELECTRON INTENSITIES', Institute of Physics Conference Series, no. 98, pp. 107-10. Berdonosova, EA, Maletskaya, NV, Kogan, EV, Kovalenko, KA, Klyamkin, SN, Dybtsev, DN & Fedin, VP 2013, 'Synthesis and gas sorption properties of halogen-doped mesoporous chromium(iii) terephthalate', Russian Chemical Bulletin, vol. 62, no. 1, pp. 157-62. Berendsen, HJC, Postma, JPM, Vangunsteren, WF, Dinola, A & Haak, JR 1984, 'MOLECULAR-DYNAMICS WITH COUPLING TO AN EXTERNAL BATH', Journal of Chemical Physics, vol. 81, no. 8, pp. 3684-90. Boot-Handford, ME, Abanades, JC, Anthony, EJ, Blunt, MJ, Brandani, S, Mac Dowell, N, Fernandez, JR, Ferrari, M-C, Gross, R, Hallett, JP, Haszeldine, RS, Heptonstall, P, Lyngfelt, A, Makuch, Z, Mangano, E, Porter, RTJ, Pourkashanian, M, Rochelle, GT, Shah, N, Yao, JG & Fennell, PS 2014, 'Carbon capture and storage update', Energy & Environmental Science, vol. 7, no. 1, pp. 130-89. Bordiga, S, Regli, L, Bonino, F, Groppo, E, Lamberti, C, Xiao, B, Wheatley, PS, Morris, RE & Zecchina, A 2007, 'Adsorption properties of HKUST-1 toward hydrogen and other small molecules monitored by IR', Physical Chemistry Chemical Physics, vol. 9, no. 21, pp. 2676-85. Bosoaga, A, Masek, O & Oakey, JE 2009, 'CO2 Capture Technologies for Cement Industry', in J Gale, H Herzog & J Braitsch (eds), Greenhouse Gas Control Technologies 9, vol. 1, pp. 133-40. Botas, JA, Calleja, G, Sanchez-Sanchez, M & Orcajo, MG 2010, 'Cobalt Doping of the MOF-5 Framework and Its Effect on Gas-Adsorption Properties', Langmuir, vol. 26, no. 8, pp. 5300-3. Bourrelly, S, Llewellyn, PL, Serre, C, Millange, F, Loiseau, T & Férey, G 2005, 'Different adsorption behaviors of methane and carbon dioxide in the isotypic nanoporous metal terephthalates MIL-53 and MIL-47', Journal of the American Chemical Society, vol. 127, no. 39, pp. 13519-21. Canivet, J, Fateeva, A, Guo, Y, Coasne, B & Farrusseng, D 2014, 'Water adsorption in MOFs: fundamentals and applications', Chemical Society Reviews, vol. 43, no. 16, pp. 5594-617. Casewit, CJ, Colwell, KS & Rappe, AK 1992, 'APPLICATION OF A UNIVERSAL FORCE-FIELD TO ORGANIC-MOLECULES', Journal of the American Chemical Society, vol. 114, no. 25, pp. 10035-46. Chałupnik, S, Franus, W, Wysocka, M & Gzyl, G 2013, 'Application of zeolites for radium removal from mine water', Environmental Science and Pollution Research, vol. 20, no. 11, pp. 7900-6.
Chandler, D 1975, 'Rough hard sphere theory of the self‐diffusion constant for molecular liquids', The Journal of Chemical Physics, vol. 62, no. 4, pp. 1358-63. Chen, L, Reiss, PS, Chong, SY, Holden, D, Jelfs, KE, Hasell, T, Little, MA, Kewley, A, Briggs, ME, Stephenson, A, Thomas, KM, Armstrong, JA, Bell, J, Busto, J, Noel, R, Liu, J, Strachan, DM, Thallapally, PK & Cooper, AI 2014, 'Separation of rare gases and chiral molecules by selective binding in porous organic cages', Nature Materials, vol. 13, p. 954. Cherp, A, Jewell, J, Vinichenko, V, Bauer, N & De Cian, E 2016, 'Global energy security under different climate policies, GDP growth rates and fossil resource availabilities', Climatic Change, vol. 136, no. 1, pp. 83-94.
58
Chrysostomidis, I, Zakkour, P, Bohm, M, Beynon, E, de Filippo, R & Lee, A 2009, 'Assessing issues of financing a CO2 transportation pipeline infrastructure', Energy Procedia, vol. 1, no. 1, pp. 1625-32. Chu, S 2009, 'Carbon Capture and Sequestration', Science, vol. 325, no. 5948, pp. 1599-. Chui, SSY, Lo, SMF, Charmant, JPH, Orpen, AG & Williams, ID 1999, 'A chemically functionalizable nanoporous material Cu-3(TMA)(2)(H2O)(3) (n)', Science, vol. 283, no. 5405, pp. 1148-50. Ciccotti, G, Ferrario, M & Schuette, C 2014, 'Molecular Dynamics Simulation'. Collins, SP & Woo, TK 2017, 'Split-Charge Equilibration Parameters for Generating Rapid Partial Atomic Charges in Metal-Organic Frameworks and Porous Polymer Networks for High-Throughput Screening', Journal of Physical Chemistry C, vol. 121, no. 1, pp. 903-10. Cormos, C-C 2012, 'Integrated assessment of IGCC power generation technology with carbon capture and storage (CCS)', Energy, vol. 42, no. 1, pp. 434-45. Cormos, CC 2014, 'Economic evaluations of coal-based combustion and gasification power plants with post-combustion CO2 capture using calcium looping cycle', Energy, vol. 78, pp. 665-73. D'Alessandro, DM, Smit, B & Long, JR 2010, 'Carbon dioxide capture: prospects for new materials', Angewandte Chemie International Edition, vol. 49, no. 35, pp. 6058-82. de Coninck, H, Stephens, JC & Metz, B 2009, 'Global learning on carbon capture and storage: A call for strong international cooperation on CCS demonstration', Energy Policy, vol. 37, no. 6, pp. 2161-5. de Pablo, JJ, Jones, B, Kovacs, CL, Ozolins, V & Ramirez, AP 2014, 'The Materials Genome Initiative, the interplay of experiment, theory and computation', Current Opinion in Solid State and Materials Science, vol. 18, no. 2, pp. 99-117. Din, XD & Michaelides, EE 1997, 'Kinetic theory and molecular dynamics simulations of microscopic flows', Physics of Fluids, vol. 9, no. 12, pp. 3915-25. Drage, TC, Snape, CE, Stevens, LA, Wood, J, Wang, J, Cooper, AI, Dawson, R, Guo, X, Satterley, C & Irons, R 2012, 'Materials challenges for the development of solid sorbents for post-combustion carbon capture', Journal of Materials Chemistry, vol. 22, no. 7, pp. 2815-23. Dreizler, RM & Gross, EKU 1990, 'Introduction', in Density Functional Theory: An Approach to the Quantum Many-Body Problem, Springer Berlin Heidelberg, Berlin, Heidelberg, pp. 1-3. Duren, T, Bae, Y-S & Snurr, RQ 2009, 'Using molecular simulation to characterise metal-organic frameworks for adsorption applications', Chemical Society Reviews, vol. 38, no. 5, pp. 1237-47. Eldevik, F, Graver, B, Torbergsen, LE & Saugerud, OT 2009, 'Development of a Guideline for Safe, Reliable and Cost Efficient Transmission of CO2 in Pipelines', Energy Procedia, vol. 1, no. 1, pp. 1579-85. Erpenbeck, JJ & Wood, WW 1982, 'Molecular-dynamics calculations of the velocity-autocorrelation function. Methods, hard-disk results', Physical Review A, vol. 26, no. 3, p. 1648.
59
Evins, R 2013, 'A review of computational optimisation methods applied to sustainable building design', Renewable and Sustainable Energy Reviews, vol. 22, no. Supplement C, pp. 230-45. Fang, SX, Tans, PP, Steinbacher, M, Zhou, LX & Luan, T 2015, 'Comparison of the regional CO2 mole fraction filtering approaches at a WMO/GAW regional station in China', Atmospheric Measurement Techniques, vol. 8, no. 12, pp. 5301-13. Fang, SX, Zhou, LX, Tans, PP, Ciais, P, Steinbacher, M, Xu, L & Luan, T 2014, 'In situ measurement of atmospheric CO2 at the four WMO/GAW stations in China', Atmospheric Chemistry and Physics, vol. 14, no. 5, pp. 2541-54. Feijani, EA, Tavasoli, A & Mahdavi, H 2015, 'Improving Gas Separation Performance of Poly(vinylidene fluoride) Based Mixed Matrix Membranes Containing Metal-Organic Frameworks by Chemical Modification', Industrial & Engineering Chemistry Research, vol. 54, no. 48, pp. 12124-34. Filipponi, A 1994, 'The radial distribution function probed by X-ray absorption spectroscopy', Journal of Physics: Condensed Matter, vol. 6, no. 41, p. 8415. Frenkel, D & Smit, B 2002, 'Understanding Molecular Simulation. Computational Science Series', Academic Press, San Diego Adcock SA, McCammon JA (2006) Molecular dynamics: survey of methods for simulating the activity of proteins. Chem Rev, vol. 106, pp. 1589-615. Furukawa, H, Cordova, KE, O’Keeffe, M & Yaghi, OM 2013, 'The Chemistry and Applications of Metal-Organic Frameworks', Science, vol. 341, no. 6149. Furukawa, H, Ko, N, Go, YB, Aratani, N, Choi, SB, Choi, E, Yazaydin, AÖ, Snurr, RQ, O’Keeffe, M, Kim, J & Yaghi, OM 2010, 'Ultrahigh Porosity in Metal-Organic Frameworks', Science, vol. 329, no. 5990, pp. 424-8. Garcia-Abuin, A, Gomez-Diaz, D & Navaza, JM 2014, 'New processes for amine regeneration', Fuel, vol. 135, pp. 191-7. Ghosh, P, Colon, YJ & Snurr, RQ 2014, 'Water adsorption in UiO-66: the importance of defects', Chemical Communications, vol. 50, no. 77, pp. 11329-31. Gibbins, J & Chalmers, H 2008, 'Carbon capture and storage', Energy Policy, vol. 36, no. 12, pp. 4317-22. Grubmuller, H, Heller, H, Windemuth, A & Schulten, K 1991, 'GENERALIZED VERLET ALGORITHM FOR EFFICIENT MOLECULAR DYNAMICS SIMULATIONS WITH LONG-RANGE INTERACTIONS', Molecular Simulation, vol. 6, no. 1-3, pp. 121-42. Hafner, J 2007, 'Materials simulations using VASP—a quantum perspective to materials science', Computer Physics Communications, vol. 177, no. 1, pp. 6-13. Haile, J 1992, Molecular dynamics simulation, vol. 18, Wiley, New York. Hamad, S, Balestra, SRG, Bueno-Perez, R, Calero, S & Ruiz-Salvador, AR 2015, 'Atomic charges for modeling metal-organic frameworks: Why and how', Journal of Solid State Chemistry, vol. 223, pp. 144-51.
60
Hamon, L, Llewellyn, PL, Devic, T, Ghoufi, A, Clet, G, Guillerm, V, Pirngruber, GD, Maurin, G, Serre, C, Driver, G, van Beek, W, Jolimaitre, E, Vimont, A, Daturi, M & Ferey, G 2009, 'Co-adsorption and Separation of CO2-CH4 Mixtures in the Highly Flexible MIL-53(Cr) MOF', Journal of the American Chemical Society, vol. 131, no. 47, pp. 17490-9. Hamon, L, Serre, C, Devic, T, Loiseau, T, Millange, F, Férey, G & Weireld, GD 2009, 'Comparative study of hydrogen sulfide adsorption in the MIL-53 (Al, Cr, Fe), MIL-47 (V), MIL-100 (Cr), and MIL-101 (Cr) metal− organic frameworks at room temperature', Journal of the American Chemical Society, vol. 131, no. 25, pp. 8775-7. Handy, NC 1996, 'Density Functional Theory', in D Bicout & M Field (eds), Quantum Mechanical Simulation Methods for Studying Biological Systems: Les Houches Workshop, May 2–7, 1995, Springer Berlin Heidelberg, Berlin, Heidelberg, pp. 1-35. Hao, G-P, Li, W-C & Lu, A-H 2011, 'Novel porous solids for carbon dioxide capture', Journal of Materials Chemistry, vol. 21, no. 18, pp. 6447-51. Hoover, WG 1985, 'CANONICAL DYNAMICS - EQUILIBRIUM PHASE-SPACE DISTRIBUTIONS', Physical Review A, vol. 31, no. 3, pp. 1695-7. Hu, X-L, Liu, F-H, Wang, H-N, Qin, C, Sun, C-Y, Su, Z-M & Liu, F-C 2014, 'Controllable synthesis of isoreticular pillared-layer MOFs: gas adsorption, iodine sorption and sensing small molecules', Journal of Materials Chemistry A, vol. 2, no. 36, pp. 14827-34. Hussain, D, Dzombak, DA, Jaramillo, P & Lowry, GV 2013, 'Comparative lifecycle inventory (LCI) of greenhouse gas (GHG) emissions of enhanced oil recovery (EOR) methods using different CO2 sources', International journal of greenhouse gas control, vol. 16, no. Supplement C, pp. 129-44. Jackson, RB, Le Quere, C, Andrew, RM, Canadell, JG, Peters, GP, Roy, J & Wu, L 2017, 'Warning signs for stabilizing global CO2 emissions', Environmental Research Letters, vol. 12, no. 11. Jelfs, KE & Cooper, AI 2013, 'Molecular simulations to understand and to design porous organic molecules', Current Opinion in Solid State and Materials Science, vol. 17, no. 1, pp. 19-30. Jung, J-Y, Huh, C, Kang, S-G, Seo, Y & Chang, D 2013, 'CO2 transport strategy and its cost estimation for the offshore CCS in Korea', Applied Energy, vol. 111, no. Supplement C, pp. 1054-60. Kärger, J 1992, 'Straightforward derivation of the long-time limit of the mean-square displacement in one-dimensional diffusion', Physical Review A, vol. 45, no. 6, p. 4173. Keskin, S & Sholl, DS 2007, 'Screening metal-organic framework materials for membrane-based methane/carbon dioxide separations', The Journal of Physical Chemistry C, vol. 111, no. 38, pp. 14055-9. Kowalczyk, A, Harnisch, E, Schwede, S, Gerber, M & Span, R 2013, 'Different mixing modes for biogas plants using energy crops', Applied Energy, vol. 112, no. Supplement C, pp. 465-72. Krausmann, F, Gingrich, S, Eisenmenger, N, Erb, K-H, Haberl, H & Fischer-Kowalski, M 2009, 'Growth in global materials use, GDP and population during the 20th century', Ecological Economics, vol. 68, no. 10, pp. 2696-705.
61
Krishna, R & Van Baten, J 2006, 'Describing binary mixture diffusion in carbon nanotubes with the Maxwell-Stefan equations. An investigation using molecular dynamics simulations', Industrial & Engineering Chemistry Research, vol. 45, no. 6, pp. 2084-93. Lamb, ML & Jorgensen, WL 1997, 'Computational approaches to molecular recognition', Current Opinion in Chemical Biology, vol. 1, no. 4, pp. 449-57. Lawler, KV, Hulvey, Z & Forster, PM 2015, 'On the importance of a precise crystal structure for simulating gas adsorption in nanoporous materials', Physical Chemistry Chemical Physics, vol. 17, no. 29, pp. 18904-7. Le Moullec, Y & Kanniche, M 2011, 'Screening of flowsheet modifications for an efficient monoethanolamine (MEA) based post-combustion CO2 capture', International journal of greenhouse gas control, vol. 5, no. 4, pp. 727-40. Lebedev, O, Millange, F, Serre, C, Van Tendeloo, G & Férey, G 2005, 'First direct imaging of giant pores of the metal-organic framework MIL-101', Chemistry of Materials, vol. 17, no. 26, pp. 6525-7. Lee, S-Y & Park, S-J 2015, 'A review on solid adsorbents for carbon dioxide capture', Journal of Industrial and Engineering Chemistry, vol. 23, no. Supplement C, pp. 1-11. Lee, ZH, Sethupathi, S, Lee, KT, Bhatia, S & Mohamed, AR 2013, 'An overview on global warming in Southeast Asia: CO2 emission status, efforts done, and barriers', Renewable & Sustainable Energy Reviews, vol. 28, pp. 71-81. Levin, K, Cashore, B, Bernstein, S & Auld, G 2012, 'Overcoming the tragedy of super wicked problems: constraining our future selves to ameliorate global climate change', Policy Sciences, vol. 45, no. 2, pp. 123-52. Li, F & Lannin, JS 1990, 'RADIAL-DISTRIBUTION FUNCTION OF AMORPHOUS-CARBON', Physical review letters, vol. 65, no. 15, pp. 1905-8. Li, J-R, Kuppler, RJ & Zhou, H-C 2009, 'Selective gas adsorption and separation in metal-organic frameworks', Chemical Society Reviews, vol. 38, no. 5, pp. 1477-504. Li, J-R, Ma, Y, McCarthy, MC, Sculley, J, Yu, J, Jeong, H-K, Balbuena, PB & Zhou, H-C 2011, 'Carbon dioxide capture-related gas adsorption and separation in metal-organic frameworks', Coordination Chemistry Reviews, vol. 255, no. 15, pp. 1791-823. Li, W, Rao, ZZ, Chung, YG & Li, S 2017, 'The Role of Partial Atomic Charge Assignment Methods on the Computational Screening of Metal-Organic Frameworks for CO2 Capture under Humid Conditions', Chemistryselect, vol. 2, no. 29, pp. 9458-65. Li, Y-W, Li, J-R, Wang, L-F, Zhou, B-Y, Chen, Q & Bu, X-H 2013, 'Microporous metal-organic frameworks with open metal sites as sorbents for selective gas adsorption and fluorescence sensors for metal ions', Journal of Materials Chemistry A, vol. 1, no. 3, pp. 495-9. Li, Y-W, Xu, J, Li, D-C, Dou, J-M, Yan, H, Hu, T-L & Bu, X-H 2015, 'Two microporous MOFs constructed from different metal cluster SBUs for selective gas adsorption', Chemical Communications, vol. 51, no. 75, pp. 14211-4.
62
Li, Y-W, Yan, H, Hu, T-L, Ma, H-Y, Li, D-C, Wang, S-N, Yao, Q-X, Dou, J-M, Xu, J & Bu, X-H 2017, 'Two microporous Fe-based MOFs with multiple active sites for selective gas adsorption', Chemical Communications, vol. 53, no. 15, pp. 2394-7. Liang, ZJ, Marshall, M & Chaffee, AL 2009, 'CO2 Adsorption-Based Separation by Metal Organic Framework (Cu-BTC) versus Zeolite (13X)', Energy & fuels, vol. 23, no. 5-6, pp. 2785-9. Liu, YY, Wang, ZYU & Zhou, HC 2012, 'Recent advances in carbon dioxide capture with metal-organic frameworks', Greenhouse Gases-Science and Technology, vol. 2, no. 4, pp. 239-59. Llewellyn, PL, Bourrelly, S, Serre, C, Vimont, A, Daturi, M, Hamon, L, De Weireld, G, Chang, JS, Hong, DY, Hwang, YK, Jhung, SH & Ferey, G 2008, 'High uptakes of CO2 and CH4 in mesoporous metal-organic frameworks MIL-100 and MIL-101', Langmuir, vol. 24, no. 14, pp. 7245-50. Lucquiaud, M & Gibbins, J 2011, 'On the integration of CO2 capture with coal-fired power plants: A methodology to assess and optimise solvent-based post-combustion capture systems', Chemical Engineering Research & Design, vol. 89, no. 9, pp. 1553-71. Luo, QX, An, BW, Ji, M, Park, SE, Hao, C & Li, YQ 2015, 'Metal-organic frameworks HKUST-1 as porous matrix for encapsulation of basic ionic liquid catalyst: effect of chemical behaviour of ionic liquid in solvent', Journal of Porous Materials, vol. 22, no. 1, pp. 247-59. Lyndon, R, Konstas, K, Thornton, AW, Seeber, AJ, Ladewig, BP & Hill, MR 2015, 'Visible Light-Triggered Capture and Release of CO2 from Stable Metal Organic Frameworks', Chemistry of Materials, vol. 27, no. 23, pp. 7882-8. Ma, L, Abney, C & Lin, W 2009, 'Enantioselective catalysis with homochiral metal-organic frameworks', Chemical Society Reviews, vol. 38, no. 5, pp. 1248-56. Maji, TK, Ohba, M & Kitagawa, S 2005, 'Transformation from a 2D stacked layer to 3D interpenetrated framework by changing the spacer functionality: Synthesis, structure, adsorption, and magnetic properties', Inorganic chemistry, vol. 44, no. 25, pp. 9225-31. Makov, G & Payne, MC 1995, 'PERIODIC BOUNDARY-CONDITIONS IN AB-INITIO CALCULATIONS', Physical Review B, vol. 51, no. 7, pp. 4014-22. Manan, ZA, Nawi, W, Alwi, SRW & Klemes, JJ 2017, 'Advances in Process Integration research for CO2 emission reduction - A review', Journal of Cleaner Production, vol. 167, pp. 1-13. Mangalapally, HP, Notz, R, Hoch, S, Asprion, N, Sieder, G, Garcia, H & Hasse, H 2009, 'Pilot plant experimental studies of post combustion CO2 capture by reactive absorption with MEA and new solvents', Energy Procedia, vol. 1, no. 1, pp. 963-70. Martin, MG 2006, 'Comparison of the AMBER, CHARMM, COMPASS, GROMOS, OPLS, TraPPE and UFF force fields for prediction of vapor–liquid coexistence curves and liquid densities', Fluid phase equilibria, vol. 248, no. 1, pp. 50-5. Maurin, G, Serre, C, Cooper, A & Ferey, G 2017, 'The new age of MOFs and of their porous-related solids', Chemical Society Reviews, vol. 46, no. 11, pp. 3104-7.
63
Meier, K, Laesecke, A & Kabelac, S 2001, 'A Molecular Dynamics Simulation Study of the Self-Diffusion Coefficient and Viscosity of the Lennard–Jones Fluid', International Journal of Thermophysics, vol. 22, no. 1, pp. 161-73. Metropolis, N, Rosenbluth, AW, Rosenbluth, MN, Teller, AH & Teller, E 1953, 'EQUATION OF STATE CALCULATIONS BY FAST COMPUTING MACHINES', Journal of Chemical Physics, vol. 21, no. 6, pp. 1087-92. Michalet, X 2010, 'Mean square displacement analysis of single-particle trajectories with localization error: Brownian motion in an isotropic medium', Physical Review E, vol. 82, no. 4, p. 041914. Millange, F, Guillou, N, Walton, RI, Greneche, J-M, Margiolaki, I & Ferey, G 2008, 'Effect of the nature of the metal on the breathing steps in MOFs with dynamic frameworks', Chemical Communications, no. 39, pp. 4732-4. Miller, DR, Akbar, SA & Morris, PA 2014, 'Nanoscale metal oxide-based heterojunctions for gas sensing: A review', Sensors and Actuators B: Chemical, vol. 204, no. Supplement C, pp. 250-72. Millward, AR & Yaghi, OM 2005, 'Metal-organic frameworks with exceptionally high capacity for storage of carbon dioxide at room temperature', Journal of the American Chemical Society, vol. 127, no. 51, pp. 17998-9. Mohor, GS & Mendiondo, EM 2017, 'Economic indicators of hydrologic drought insurance under water demand and climate change scenarios in a Brazilian context', Ecological Economics, vol. 140, pp. 66-78. Mosher, K, He, J, Liu, Y, Rupp, E & Wilcox, J 2013, 'Molecular simulation of methane adsorption in micro- and mesoporous carbons with applications to coal and gas shale systems', International Journal of Coal Geology, vol. 109-110, no. Supplement C, pp. 36-44. Nijboer, B & Van Hove, L 1952, 'Radial distribution function of a gas of hard spheres and the superposition approximation', Physical Review, vol. 85, no. 5, p. 777. Nosé, S 1984, 'A molecular dynamics method for simulations in the canonical ensemble', Molecular physics, vol. 52, no. 2, pp. 255-68. Nose, S & Klein, ML 1983, 'CONSTANT PRESSURE MOLECULAR-DYNAMICS FOR MOLECULAR-SYSTEMS', Molecular physics, vol. 50, no. 5, pp. 1055-76. Nugent, P, Belmabkhout, Y, Burd, SD, Cairns, AJ, Luebke, R, Forrest, K, Pham, T, Ma, S, Space, B & Wojtas, L 2013, 'Porous materials with optimal adsorption thermodynamics and kinetics for CO2 separation', Nature, vol. 495, no. 7439, pp. 80-4. Orio, M, Pantazis, DA & Neese, F 2009, 'Density functional theory', Photosynthesis Research, vol. 102, no. 2, pp. 443-53. Park, J, Lively, RP & Sholl, DS 2017, 'Establishing upper bounds on CO2 swing capacity in sub-ambient pressure swing adsorption via molecular simulation of metal-organic frameworks', Journal of Materials Chemistry A, vol. 5, no. 24, pp. 12258-65.
64
Parkes, MV, Demir, H, Teich-McGoldrick, SL, Sholl, DS, Greathouse, JA & Allendorf, MD 2014, 'Molecular dynamics simulation of framework flexibility effects on noble gas diffusion in HKUST-1 and ZIF-8', Microporous and Mesoporous Materials, vol. 194, no. Supplement C, pp. 190-9. Pietzcker, RC, Longden, T, Chen, W, Fu, S, Kriegler, E, Kyle, P & Luderer, G 2014, 'Long-term transport energy demand and climate policy: Alternative visions on transport decarbonization in energy-economy models', Energy, vol. 64, no. Supplement C, pp. 95-108. Pinto, DDD, Knuutila, H, Fytianos, G, Haugen, G, Mejdell, T & Svendsen, HF 2014, 'CO2 post combustion capture with a phase change solvent. Pilot plant campaign', International journal of greenhouse gas control, vol. 31, pp. 153-64. Pivkin, IV & Karniadakis, GE 2005, 'A new method to impose no-slip boundary conditions in dissipative particle dynamics', Journal of Computational Physics, vol. 207, no. 1, pp. 114-28. Pongsajanukul, P, Parasuk, V, Fritzsche, S, Assabumrungrat, S, Wongsakulphasatch, S, Bovornratanaraks, T & Chokbunpiam, T 2017, 'Theoretical study of carbon dioxide adsorption and diffusion in MIL-127 (Fe) metal organic framework', Chemical Physics, vol. 491, pp. 118-25. Quadrelli, R & Peterson, S 2007, 'The energy–climate challenge: Recent trends in CO2 emissions from fuel combustion', Energy Policy, vol. 35, no. 11, pp. 5938-52. Randolph, JB & Saar, MO 2011, 'Coupling carbon dioxide sequestration with geothermal energy capture in naturally permeable, porous geologic formations: Implications for CO2 sequestration', Energy Procedia, vol. 4, no. Supplement C, pp. 2206-13. Rao, AB & Rubin, ES 2002, 'A technical, economic, and environmental assessment of amine-based CO2 capture technology for power plant greenhouse gas control', Environmental science & technology, vol. 36, no. 20, pp. 4467-75. Rappe, AK, Casewit, CJ, Colwell, KS, Goddard, WA & Skiff, WM 1992, 'UFF, A FULL PERIODIC-TABLE FORCE-FIELD FOR MOLECULAR MECHANICS AND MOLECULAR-DYNAMICS SIMULATIONS', Journal of the American Chemical Society, vol. 114, no. 25, pp. 10024-35. Rappe, AK & Goddard, WA 1991, 'CHARGE EQUILIBRATION FOR MOLECULAR-DYNAMICS SIMULATIONS', Journal of Physical Chemistry, vol. 95, no. 8, pp. 3358-63. Rochelle, G, Chen, E, Freeman, S, Van Wagener, D, Xu, Q & Voice, A 2011, 'Aqueous piperazine as the new standard for CO2 capture technology', Chemical engineering journal, vol. 171, no. 3, pp. 725-33. Rochelle, GT 2009, 'Amine Scrubbing for CO2 Capture', Science, vol. 325, no. 5948, pp. 1652-4. Rossi, TM, Campos, JC & Souza, MMVM 2016, 'CO2 capture by Mg–Al and Zn–Al hydrotalcite-like compounds', Adsorption, vol. 22, no. 2, pp. 151-8. Sabouni, R, Kazemian, H & Rohani, S 2014, 'Carbon dioxide capturing technologies: a review focusing on metal organic framework materials (MOFs)', Environmental Science and Pollution Research, vol. 21, no. 8, pp. 5427-49.
65
Saha, S, Chandra, S, Garai, B & Banerjee, R 2012, 'Carbon dioxide capture by metal organic frameworks', Indian Journal of Chemistry Section a-Inorganic Bio-Inorganic Physical Theoretical & Analytical Chemistry, vol. 51, no. 9-10, pp. 1223-30. Salles, F, Ghoufi, A, Maurin, G, Bell, RG, Mellot-Draznieks, C & Ferey, G 2008, 'Molecular Dynamics Simulations of Breathing MOFs: Structural Transformations of MIL-53(Cr) upon Thermal Activation and CO2 Adsorption', Angewandte Chemie-International Edition, vol. 47, no. 44, pp. 8487-91. Salles, F, Jobic, H, Devic, T, Guillerm, V, Serre, C, Koza, MM, Ferey, Gr & Maurin, G 2013, 'Diffusion of Binary CO2/CH4 Mixtures in the MIL-47 (V) and MIL-53 (Cr) Metal–Organic Framework Type Solids: A Combination of Neutron Scattering Measurements and Molecular Dynamics Simulations', The Journal of Physical Chemistry C, vol. 117, no. 21, pp. 11275-84. Samanta, A, Zhao, A, Shimizu, GKH, Sarkar, P & Gupta, R 2012, 'Post-Combustion CO2 Capture Using Solid Sorbents: A Review', Industrial & Engineering Chemistry Research, vol. 51, no. 4, pp. 1438-63. Satoh, A 2010, Introduction to practice of molecular simulation: molecular dynamics, Monte Carlo, Brownian dynamics, Lattice Boltzmann and dissipative particle dynamics, Elsevier. Schlör, H, Fischer, W & Hake, J-F 2015, 'The system boundaries of sustainability', Journal of Cleaner Production, vol. 88, no. Supplement C, pp. 52-60. Seema, H, Kemp, KC, Le, NH, Park, S-W, Chandra, V, Lee, JW & Kim, KS 2014, 'Highly selective CO2 capture by S-doped microporous carbon materials', Carbon, vol. 66, no. Supplement C, pp. 320-6. Shackley, S & Verma, P 2008, 'Tackling CO2 reduction in India through use of CO2 capture and storage (CCS): Prospects and challenges', Energy Policy, vol. 36, no. 9, pp. 3554-61. Shi, J-T, Yue, K-F, Liu, B, Zhou, C-s, Liu, Y-L, Fang, Z-G & Wang, Y-Y 2014, 'Two porous metal-organic frameworks (MOFs) based on mixed ligands: synthesis, structure and selective gas adsorption', CrystEngComm, vol. 16, no. 15, pp. 3097-102. Skoulidas, AI & Sholl, DS 2005, 'Self-diffusion and transport diffusion of light gases in metal-organic framework materials assessed using molecular dynamics simulations', The Journal of Physical Chemistry B, vol. 109, no. 33, pp. 15760-8. Takakura, J, Fujimori, S, Takahashi, K, Hijioka, Y, Hasegawa, T, Honda, Y & Masui, T 2017, 'Cost of preventing workplace heat-related illness through worker breaks and the benefit of climate-change mitigation', Environmental Research Letters, vol. 12, no. 6. Thommes, M & Cychosz, KA 2014, 'Physical adsorption characterization of nanoporous materials: progress and challenges', Adsorption, vol. 20, no. 2, pp. 233-50. Tian, Z, Dai, S & Jiang, D-e 2016, 'What can molecular simulation do for global warming?', Wiley Interdisciplinary Reviews: Computational Molecular Science, vol. 6, no. 2, pp. 173-97. Torrisi, A, Bell, RG & Mellot-Draznieks, C 2010, 'Functionalized MOFs for Enhanced CO2 Capture', Crystal Growth & Design, vol. 10, no. 7, pp. 2839-41.
66
Tudisco, C, Zolubas, G, Seoane, B, Zafarani, HR, Kazemzad, M, Gascon, J, Hagedoorn, PL & Rassaei, L 2016, 'Covalent immobilization of glucose oxidase on amino MOFs via post-synthetic modification', RSC Advances, vol. 6, no. 109, pp. 108051-5. Vogiatzis, KD, Mavrandonakis, A, Klopper, W & Froudakis, GE 2009, 'Ab initio Study of the Interactions between CO2 and N-Containing Organic Heterocycles', ChemPhysChem, vol. 10, no. 2, pp. 374-83. Vujic, B & Lyubartsev, AP 2017, 'Computationally based analysis of the energy efficiency of a CO2 capture process', Chemical Engineering Science, vol. 174, pp. 174-88. Waisman, E 1973, 'The radial distribution function for a fluid of hard spheres at high densities: mean spherical integral equation approach', Molecular physics, vol. 25, no. 1, pp. 45-8. Walton, KS, Millward, AR, Dubbeldam, D, Frost, H, Low, JJ, Yaghi, OM & Snurr, RQ 2008, 'Understanding inflections and steps in carbon dioxide adsorption isotherms in metal-organic frameworks', Journal of the American Chemical Society, vol. 130, no. 2, pp. 406-+. Wang, Z & Cohen, SM 2009, 'Postsynthetic modification of metal-organic frameworks', Chemical Society Reviews, vol. 38, no. 5, pp. 1315-29. Wilmer, CE & Snurr, RQ 2011, 'Towards rapid computational screening of metal-organic frameworks for carbon dioxide capture: Calculation of framework charges via charge equilibration', Chemical engineering journal, vol. 171, no. 3, pp. 775-81. Wu, H, Simmons, JM, Srinivas, G, Zhou, W & Yildirim, T 2010, 'Adsorption Sites and Binding Nature of CO2 in Prototypical Metal-Organic Frameworks: A Combined Neutron Diffraction and First-Principles Study', Journal of Physical Chemistry Letters, vol. 1, no. 13, pp. 1946-51. Xian, S, Peng, J, Zhang, Z, Xia, Q, Wang, H & Li, Z 2015, 'Highly enhanced and weakened adsorption properties of two MOFs by water vapor for separation of CO2/CH4 and CO2/N2 binary mixtures', Chemical engineering journal, vol. 270, no. Supplement C, pp. 385-92. Xie, J, Yan, N, Qu, Z & Yang, S 2012, 'Synthesis, characterization and experimental investigation of Cu-BTC as CO2 adsorbent from flue gas', Journal of Environmental Sciences, vol. 24, no. 4, pp. 640-4. Yakovenko, AA, Reibenspies, JH, Bhuvanesh, N & Zhou, HC 2013, 'Generation and applications of structure envelopes for porous metal-organic frameworks', Journal of Applied Crystallography, vol. 46, pp. 346-53. Yan, X, Komarneni, S, Zhang, Z & Yan, Z 2014, 'Extremely enhanced CO2 uptake by HKUST-1 metal–organic framework via a simple chemical treatment', Microporous and Mesoporous Materials, vol. 183, no. Supplement C, pp. 69-73. Yan, XL, Li, SN, Jiang, YC, Hu, MC & Zhai, QG 2015, 'Synthesis, crystal structures and gas adsorption of two porous pillar-layered MOFs decorated with different functional groups', Inorganic Chemistry Communications, vol. 62, pp. 107-10. Yang, Q, Vaesen, S, Vishnuvarthan, M, Ragon, F, Serre, C, Vimont, A, Daturi, M, De Weireld, G & Maurin, G 2012, 'Probing the adsorption performance of the hybrid porous MIL-68(Al): a synergic
67
combination of experimental and modelling tools', Journal of Materials Chemistry, vol. 22, no. 20, pp. 10210-20. Yang, Q, Xue, C, Zhong, C & Chen, JF 2007, 'Molecular simulation of separation of CO2 from flue
gases in CU‐BTC metal‐organic framework', AIChE Journal, vol. 53, no. 11, pp. 2832-40. Yang, Q & Zhong, C 2006, 'Molecular simulation of carbon dioxide/methane/hydrogen mixture adsorption in metal-organic frameworks', The Journal of Physical Chemistry B, vol. 110, no. 36, pp. 17776-83. Yang, QY, Zhong, CL & Chen, JF 2008, 'Computational study of CO2 storage in metal-organic frameworks', Journal of Physical Chemistry C, vol. 112, no. 5, pp. 1562-9. Yazaydın, AO, Benin, AI, Faheem, SA, Jakubczak, P, Low, JJ, Willis, RR & Snurr, RQ 2009, 'Enhanced CO2 adsorption in metal-organic frameworks via occupation of open-metal sites by coordinated water molecules', Chemistry of Materials, vol. 21, no. 8, pp. 1425-30. Yazaydin, AO, Snurr, RQ, Park, TH, Koh, K, Liu, J, LeVan, MD, Benin, AI, Jakubczak, P, Lanuza, M, Galloway, DB, Low, JJ & Willis, RR 2009, 'Screening of Metal-Organic Frameworks for Carbon Dioxide Capture from Flue Gas Using a Combined Experimental and Modeling Approach', Journal of the American Chemical Society, vol. 131, no. 51, pp. 18198-+. Ye, S, Jiang, X, Ruan, L-W, Liu, B, Wang, Y-M, Zhu, J-F & Qiu, L-G 2013, 'Post-combustion CO2 capture with the HKUST-1 and MIL-101(Cr) metal–organic frameworks: Adsorption, separation and regeneration investigations', Microporous and Mesoporous Materials, vol. 179, no. Supplement C, pp. 191-7. Yu, C-H, Huang, C-H & Tan, C-S 2012, 'A review of CO2 capture by absorption and adsorption', Aerosol Air Qual. Res, vol. 12, no. 5, pp. 745-69. Yu, CH, Huang, CH & Tan, CS 2012, 'A Review of CO2 Capture by Absorption and Adsorption', Aerosol and Air Quality Research, vol. 12, no. 5, pp. 745-69. Yu, M, Yankovich, AB, Kaczmarowski, A, Morgan, D & Voyles, PM 2016, 'Integrated Computational and Experimental Structure Refinement for Nanoparticles', Acs Nano, vol. 10, no. 4, pp. 4031-8. Zeng, Q, Yu, A & Lu, G 2010, 'Evaluation of Interaction Forces between Nanoparticles by Molecular Dynamics Simulation', Industrial & Engineering Chemistry Research, vol. 49, no. 24, pp. 12793-7. Zhang, S, Yang, Q, Liu, X, Qu, X, Wei, Q, Xie, G, Chen, S & Gao, S 2016, 'High-energy metal–organic frameworks (HE-MOFs): Synthesis, structure and energetic performance', Coordination Chemistry Reviews, vol. 307, no. Part 2, pp. 292-312. Zhang, Z, Zhao, Y, Gong, Q, Li, Z & Li, J 2013, 'MOFs for CO2 capture and separation from flue gas mixtures: the effect of multifunctional sites on their adsorption capacity and selectivity', Chemical Communications, vol. 49, no. 7, pp. 653-61. Zhao, L, Yang, Q, Ma, Q, Zhong, C, Mi, J & Liu, D 2011, 'A force field for dynamic Cu-BTC metal-organic framework', Journal of molecular modeling, vol. 17, no. 2, pp. 227-34.
68
Zhou, H-C, Long, JR & Yaghi, OM 2012, 'Introduction to metal–organic frameworks', Chemical Reviews, vol. 112, no. 2, pp. 673-4. Zhou, Z, He, C, Xiu, JH, Yang, L & Duan, CY 2015, 'Metal-Organic Polymers Containing Discrete Single-Walled Nanotube as a Heterogeneous Catalyst for the Cycloaddition of Carbon Dioxide to Epoxides', Journal of the American Chemical Society, vol. 137, no. 48, pp. 15066-9.