H2 storage and CO2 capture on a nanoscale metal organic framework with high thermal stability

Article abstract of DOI:10.1039/c1cc15106a

A nanoscale aluminium-based metal organic framework (NMOF) with high thermal stability has been synthesized, which shows high H₂ and CO₂ uptake capacities and an excellent selectivity for CO₂ over N₂ and O₂

Full text of DOI:10.1039/c1cc15106a

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COMMUNICATION
H2 storage and CO2 capture on a nanoscale metal organic framework
with high thermal stabilityw
Jian Zhang,a Lixian Sun,*ac Fen Xu,*b Fen Li,a Huai-Ying Zhou,c Ying-Liang Liu,d
Zelimir Gabelicae and Christoph Schickf
Received 17th August 2011, Accepted 20th November 2011
DOI: 10.1039/c1cc15106a
A
nanoscale aluminium-based metal organic framework
NMOF (CID-1) built up from Zn(II) metallic ions linked to
isophthalate and 4,40-bipyridyl ligands, showing methanol
adsorption capacities almost identical to its bulky counterpart
(CID-1 macrocrystals), but the shapes of the methanol sorption
isotherms differed significantly and the adsorption kinetics
increased dramatically.8
(NMOF) with high thermal stability has been synthesized, which
shows high H2 and CO2 uptake capacities and an excellent
selectivity for CO2 over N2 and O2.
Metal–organic frameworks (MOFs) have attracted considerable
attention in recent years for gas storage,1 separation,2 and
catalysis applications.3 Traditionally, syntheses of MOFs have
been mainly focused on yielding high quality single crystalline
samples suitable for structural analysis. Nevertheless, nanosizing
is a very effective strategy for the development of new materials
with novel and often improved properties compared to traditional
materials.4,5 Recently, a few groups had reported the syntheses
of nanosized MOF crystallites (NMOF), which are an attractive
new class of materials used for innovative applications in drug
delivery, imaging probes, photonics and biosensing.6
In this study, we focus on a porous Al-based metal organic
framework [Al(OH)(NDC), NDC stands for 1,4-naphthalene-
dicarboxylic acid] that involves a three-dimensional network
with two types of 1D square-shaped channels.9 Here, we
report original synthesis conditions leading to nanosized
Al(OH)(NDC)ꢀDMF particles prepared using Al(NO3)3ꢀ9H2O
and H2NDC under solvothermal (DMF) conditions.
The morphologies and the particle sizes of NMOF were
investigated by scanning electron microscopy (SEM) and
transmission electron microscopy (TEM). SEM and TEM
pictures clearly reveal that nanoscale MOF particles (o100 nm)
are obtained when DMF is used as a solvent (NMOF), as
shown in Fig. 1.
Because bulky porous MOFs already proved to be very
performing for gas sorption, separation and purification, their
nanoscale counterparts are expected to exhibit interesting, novel
and even enhanced gas sorption properties due to textural or
morphological changes such as an increased crystallite interface
area or a decreased diffusion distance.7,8 The porous nanosized
MOF MIL-101 prepared using the microwave method exhibits
a large uptake and significantly rapid sorption kinetics of
benzene, making it a potential candidate for the sorptive
removal of volatile organic compounds (VOCs) and other
unwanted organic contaminants.7 Tanaka et al. reported a
The crystalline nature of NMOF was confirmed by powder
X-ray diffraction (PXRD) (Fig. 2a). PXRD patterns of our
NMOF samples are identical to the pattern of Al(OH)(NDC)
reported by Comotti et al.,9 thereby confirming the same
structural topology of all these solids. Moreover, most of the
diffraction peaks of the NMOF samples are broadened due to
the restricted size of its crystallites (about 51 nm, calculated by
the Scherrer equation using the 8.41 peak as reference).
The IR spectrum (Fig. S1, ESIw) of as-synthesized and dried
(50 1C) NMOF sample confirms the Al(OH)(NDC) composition
as ascertained by the typical vibrational bands in the region
1400–1700 cmꢁ1 that characterize carboxylic functions. The IR
a Materials and Thermochemistry Laboratory, Dalian National
Laboratory for Clean Energy, Dalian Institute of Chemical Physics,
Chinese Academy of Sciences, Dalian, 116023, China.
E-mail: lxsun@dicp.ac.cn; Fax: +86-0411-84379213;
Tel: +86-0411-84379213
b Faculty of Chemistry and Chemical Engineering, Liaoning Normal
University, Dalian, 116029, China. E-mail: xufen@lnnu.edu.cn
c Dept Mat Sci & Engn, Guilin Univ Elect Technol, Guilin 541004,
China
d Dept Chem, Jinan Univ, Guangzhou 510632, Guangdong, China
e
´
Universite de Haute Alsace, ENSCMu, Lab. LPI-GSEC, 3,
Rue A. Werner, F-68094, Mulhouse Cedex, France
f Institute of Physics, Universitat Rostock, Rostock D-18059, Germany
¨
w Electronic supplementary information (ESI) available: Additional
details of the synthesis of NMOF, low-pressure gas adsorption
measurements, determination of isosteric heats of adsorption, hydrogen
adsorption kinetics measurements, IR spectra, and other physical
measurements. See DOI: 10.1039/c1cc15106a
Fig. 1 (a) SEM image and (b) TEM image of NMOF as synthesized.
Chem. Commun., 2012, 48, 759–761 759
c
This journal is The Royal Society of Chemistry 2012

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Fig. 2 (a) Experimental PXRD patterns and (b) TG profile of
NMOF (heating rate: 5 1C minꢁ1 in air flow).
Fig. 4 (a) N2 sorption isotherms and (b) H2 sorption isotherms. In
the isotherms, solid and open markers represent adsorption and
desorption points respectively.
spectrum shows the presence of free –CQO bands of the DMF
moieties at 1670 cmꢁ1 (Fig. S1a, ESIw), confirming the
incorporation of the DMF molecules within the pores. In the
case of NMOF after activation, the absence of the absorption
band around 1670 cmꢁ1 indicates that the DMF has been
totally removed from the channels after activation at 200 1C
overnight (Fig. S1b, ESIw), although TG data indicate that
DMF is completely evacuated only at B300 1C.
The TG curve of the as synthesized and dried (50 1C)
NMOF shows two main events occurring between the room
temperature and 750 1C at a heating rate of 5 1C minꢁ1 under air
flow (Fig. 2b). A gradual weight-loss step of 20% corresponds to
the removal of one guest DMF molecule per Al(OH)(NDC)
(calc.: 21%) from the large nanochannels of NMOF. A long
plateau up to 500 1C with almost no weight losses is recorded
thereby illustrating the high thermal stability of the frameworks
for NMOF. The second event, observed above 500 1C, corre-
sponds to the sudden oxidative degradation of the linkers from
the framework, Al2O3 being the only residual solid at the end
of the calcination process.
To acquire more information about the porous structure,
N2 sorption isotherms were recorded for NMOF at 77 K
(Fig. 4a). The isotherm profile (Fig. 4a) of NMOF was of type I,
confirming a microporous behavior.10 H4-type hysteresis loop
(P/Po range 0.80–1.00) was observed for the nanosized
Al(OH)(NDC) material corresponding to the filling of inter-
crystalline mesopores created upon nanocrystallite packing. The
N2 volume adsorbed by NMOF is 163 cm3 gꢁ1 at 0.005 P/Po
(Standard Temperature and Pressure, STP) (Fig. 4a), which is
far higher than that reported in the literature.9 The BET specific
surface area (SBET) of NMOF is 761 m2 gꢁ1
.
The uptake capacities for H2 (kinetic diameter = 2.8 A) were
measured at 77, 87, and 97 K (Fig. 4b). The H2 adsorption
amount on nanocrystalline Al(OH)(NDC) was 142 cm3 gꢁ1
(12.7 mg gꢁ1) at 77 K and 817 mm Hg (Fig. 4b), a value higher
than those measured for most of the nanosized MOFs or CPs,
such as ICP-3 (or -5), Cr-BDC, CPP-3, Carborane-Co(II)-3 (or -4)
under the same conditions.11 Furthermore, the H2 uptake
capacity of NMOF is also higher than that of microcrystalline
Al(OH)(NDC) (MMOF) prepared by the hydrothermal synthesis
(see Fig. S2, ESIw). The results confirm that our solvothermal
synthesis procedure with DMF solvent is more efficient than the
literature recipe.9
To further illustrate the thermal stability of NMOF, we
performed the PXRD measurements of the as-synthesized
samples in air at elevated temperature (Fig. 3). When the
sample is heated to 200 1C, the intensity of the XRD peaks
remarkably increases due to the enhancement of the electron
density contrast caused by the removal of DMF molecules
from the pores.9 Before the NMOF framework collapses
(about 500 1C), no phase transition is detected. The results
from TG characterization and PXRD measurements confirm
the high thermal stability and the rigidity of the NMOF.
To better understand the interaction between adsorbates
and the framework, the isosteric heat of adsorption for H2 as a
function of H2 uptake was determined using the Clausius–
Clapeyron equation. As shown in Fig. S3 (ESIw), the heat of
adsorption is B6.3 kJ molꢁ1 and constant for NMOF.
The high-pressure hydrogen storage performance was also
measured with a commercial pressure-composition isotherm
(PCI) unit provided by Advanced Materials Corporation
(Fig. S4a, ESIw). The hydrogen uptake of NMOF at 77 K
and 30 atm reaches 21.9 mg gꢁ1. Moreover, the kinetics of
adsorption of H2 on NMOF was measured at 77 K. Fig. S4b
(ESIw) shows the kinetic curve for H2 uptake versus time. The
H2 adsorption rate of NMOF reveals that within the short
time of about 100 s, H2 adsorption reaches B98% saturation.
To examine the separation capability of NMOF for various
gases, single-component gas sorption experiments were carried
out on CO2 (3.3 A), CH4 (3.8 A), N2 (3.64 A) and O2 (3.46 A)
at 273 K and up to 777 mm Hg (Fig. 5a).
The uptake capacities for CO2 were measured at 273 K
(Fig. 5a) and 298 K (Fig. S5, ESIw). The CO2 isotherm is
completely reversible at 273 K, exhibiting a steep rise at low
pressures, and reaches a maximum of 71 cm3 gꢁ1 (139 mg gꢁ1
)
Fig. 3 Results of the temperature-dependent PXRD study of as
synthesized NMOF in air.
c
760 Chem. Commun., 2012, 48, 759–761
This journal is The Royal Society of Chemistry 2012

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This work was financially supported by the ‘‘973 Project’’
(2010CB631303), NSFC (20833009, 20903095, 20873148,
U0734005, 51071081, 51071146, 51101145 and 51102230),
LNSFC (No. 20102224), Liaoning BaiQianWan Talents
Program (No. 2010921050), Liaoning Education Committee
(L2010223) and IUPAC (Project No. 2008-006-3-100). The
authors would like to thank Dr Zheling Zhang and Jeffrey Yang
(Quantachrome Instruments, USA) for helpful discussions.
Notes and references
1 (a) N. L. Rosi, J. Eckert, M. Eddaoudi, D. T. Vodak, J. Kim,
M. O’Keeffe and O. M. Yaghi, Science, 2003, 300, 1127–1129;
(b) M. Dinca, A. Dailly, Y. Liu, C. M. Brown, D. A. Neumann and
J. R. Long, J. Am. Chem. Soc., 2006, 128, 16876–16883;
(c) M. Latroche, S. Surble, C. Serre, C. Mellot-Draznieks,
P. L. Llewellyn, J. H. Lee, J. S. Chang, S. H. Jhung and
´
G. Ferey, Angew. Chem., Int. Ed., 2006, 45, 8227–8231.
2 J. B. Lin, W. Xue, J. P. Zhang and X. M. Chen, Chem. Commun.,
2011, 47, 926–928.
3 L. X. Shi and C. D. Wu, Chem. Commun., 2011, 47, 2928–2930.
4 A. Carne, C. Carbonell, I. Imaz and D. Maspoch, Chem. Soc. Rev.,
2011, 40, 291–305.
5 G. Z. Yuan, C. F. Zhu, Y. Liu and Y. Cui, Chem. Commun., 2011,
47, 3180–3182.
Fig. 5 (a) Gases sorption isotherms on NMOF at 273 K and (b) heat
of adsorption isotherms at different CO2 and CH4 loadings. In the
isotherms, solid and open markers represent adsorption and
desorption points respectively.
at 273 K and 777 mm Hg, which is higher compared to the
corresponding values of some representative MOFs and
ZIFs.12 The specific surface area of NMOF calculated by
CO2 adsorption data is 767 m2 gꢁ1, which are in agreement
with the value of NMOF based on the N2 adsorption. We also
calculated the isosteric heat of adsorption (Qst) for CO2 using
adsorption data collected at 273 and 298 K by the Clausius–
Clapeyron equation. Qst for CO2 is B23 kJ molꢁ1 in the
adsorption region from 5 cm3 gꢁ1 to 35 cm3 gꢁ1 (Fig. 5b).
The CH4 uptake capacity of NMOF is 19 cm3 gꢁ1 at 273 K
and 777 mm Hg. Qst for CH4 is B18 kJ molꢁ1, which is much
lower than that for CO2. We attributed the significant difference
in the adsorbed amounts and the heats of adsorption for CO2
and CH4 to the fact that CO2 has a quadrupole moment,
whereas CH4 is nonpolar, so the stronger affinity of CO2 for
the material adsorption sites, as compared to CH4.
6 (a) W. J. Rieter, K. M. L. Taylor, H. Y. An, W. L. Lin and
W. B. Lin, J. Am. Chem. Soc., 2006, 128, 9024–9025;
(b) A. M. Spokoyny, D. Kim, A. Sumrein and C. A. Mirkin,
Chem. Soc. Rev., 2009, 38, 1218–1227; (c) W. B. Lin, W. J. Rieter
and K. M. L. Taylor, Angew. Chem., Int. Ed., 2009, 48, 650–658.
7 S. H. Jhung, J. H. Lee, J. W. Yoon, C. Serre, G. Fe
J. S. Chang, Adv. Mater., 2007, 19, 121–124.
´
rey and
8 D. Tanaka, A. Henke, K. Albrecht, M. Moeller, K. Nakagawa,
S. Kitagawa and J. Groll, Nat. Chem., 2010, 2, 410–416.
9 A. Comotti, S. Bracco, P. Sozzani, S. Horike, R. Matsuda, J. Chen,
M. Takata, Y. Kubota and S. Kitagawa, J. Am. Chem. Soc., 2008,
130, 13664–13672.
10 K. S. W. Sing, D. H. Everett, R. A. W. Haul, L. Moscou,
R. A. Pierotti, J. Rouquerol and T. Siemieniewska, Pure Appl.
Chem., 1985, 57, 603–619.
Comparatively, the N2 and O2 uptakes at 273 K and 777 mm
Hg were only 4.5 cm3 gꢁ1 and 5.2 cm3 gꢁ1, respectively. The
initial slopes of CO2, CH4, N2 and O2 adsorption isotherms
were calculated, and the ratios of these slopes were used to
estimate the adsorption selectivity for CO2 over CH4, N2 or
O2.13 From these data (Fig. S6, ESIw), the calculated CO2/CH4
selectivity was 4.4 : 1, CO2/N2 selectivity was 19.6 : 1 and
CO2/O2 selectivity was 18.8 : 1 at 273 K.
11 (a) Y. M. Jeon, G. S. Armatas, J. Heo, M. G. Kanatzidis and
C. A. Mirkin, Adv. Mater., 2008, 20, 2105–2110; (b) Z. F. Xin,
J. F. Bai, Y. M. Shen and Y. Pan, Cryst. Growth Des., 2010, 10,
2451–2454; (c) O. K. Farha, A. M. Spokoyny, K. L. Mulfort,
S. Galli, J. T. Hupp and C. A. Mirkin, Small, 2009, 5, 1727–1731;
(d) W. Cho, H. J. Lee and M. Oh, J. Am. Chem. Soc., 2008, 130,
16943–16946; (e) Y. M. Jeon, G. S. Armatas, D. Kim,
M. G. Kanatzidis and C. A. Mirkin, Small, 2009, 5, 46–50.
12 (a) H. Furukawa, J. Kim, N. W. Ockwig, M. O’Keeffe and
O. M. Yaghi, J. Am. Chem. Soc., 2008, 130, 11650–11661;
(b) R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa,
M. O’Keeffe and O. M. Yaghi, Science, 2008, 319, 939–943;
(c) E. Neofotistou, C. D. Malliakas and P. N. Trikalitis, Chem.–Eur.
J., 2009, 15, 4523–4527; (d) A. Phan, C. J. Doonan, F. J. Uribe-
Romo, C. B. Knobler, M. O’Keeffe and O. M. Yaghi, Acc. Chem.
Res., 2010, 43, 58–67.
In summary, here we reported for the first time a synthesis
procedure yielding pure uniformly nanosized Al(OH)(NDC)
(NMOF) crystallites with high thermal stability. NMOF can
adsorb 12.7 mg gꢁ1 and 21.9 mg gꢁ1 hydrogen at 77 K under
about 1 atm and 30 atm, respectively. Moreover, the kinetics
experiment indicates that nanocrystalline NMOF adsorbs H2 up
to B98% saturation within about 100 s at 77 K. It shows high
CO2 sorption capacity and excellent selectivity for CO2 over N2
and O2. It is concluded that NMOF is a promising candidate for
H2 storage, for CO2 capture, and for gas separation.
13 (a) J. An, S. J. Geib and N. L. Rosi, J. Am. Chem. Soc., 2010, 132,
38–39; (b) R. Banerjee, H. Furukawa, D. Britt, C. Knobler,
M. O’Keeffe and O. M. Yaghi, J. Am. Chem. Soc., 2009, 131,
3875–3877.
c
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Chem. Commun., 2012, 48, 759–761 761