Simple Continuous High-Pressure Hydrogen Production and Separation System from Formic Acid under Mild Temperatures

Article abstract of DOI:10.1002/cctc.201501296

A simple and continuous high-pressure (>120MPa) hydrogen production system was developed by the selective decomposition of formic acid at 80°C using an iridium complex as a catalyst, with a view to its application in future hydrogen fuel filling stations. The system is devoid of any compressing system. The described method can provide high-pressure H₂ with 85 % purity after applying an effective gas-liquid separation process to separate the generated gas obtained from the decomposition of formic acid (H₂/CO₂=1:1). The efficiency of the catalyst lies with its high turnover frequency (1800h^-1 at 40MPa) to produce high-pressure H₂ with a good lifetime of >40h. Interestingly, only very low levels carbon monoxide (less than 6vol ppm) were detected in the generated gas, even at 120MPa. The power to move you: High-pressure gas over 120MPa can be generated continuously by the decomposition of formic acid into H₂ and CO₂ at 80°C under mild reaction conditions in the presence of a water-soluble homogeneous iridium catalyst without any compressing procedure. 85mol % of high-pressure H₂ gas can be concentrated from the generated gas by a simple vapor-liquid separation method.

Full text of DOI:10.1002/cctc.201501296

DOI: 10.1002/cctc.201501296
Communications
Simple Continuous High-Pressure Hydrogen Production
and Separation System from Formic Acid under Mild
Temperatures
[
a, e]
[b, e]
[c, e]
[d, e]
Masayuki Iguchi, a,Yeu] ichiro Himeda,
Yuichi Manaka,
Koichi Matsuoka,
and
[
Hajime Kawanami*
[
1]
A simple and continuous high-pressure (>120 MPa) hydrogen
production system was developed by the selective decomposi-
tion of formic acid at 808C using an iridium complex as a cata-
lyst, with a view to its application in future hydrogen fuel fill-
ing stations. The system is devoid of any compressing system.
fuels and contributes to the zero-emission technology. Even
though fuel cell vehicles (FCVs) with on-board high-pressure
H cylinders up to 70 MPa have recently become available, ap-
2
plications of H as an alternative fuel are still in their infancy
2
due to several challenges, particularly regarding the storage of
H and the generation of high-pressure H due to its low volu-
The described method can provide high-pressure H with 85%
2
2
2
[
1,2]
purity after applying an effective gas–liquid separation process
to separate the generated gas obtained from the decomposi-
tion of formic acid (H /CO =1:1). The efficiency of the catalyst
metric energy density and gaseous properties.
The current
system at hydrogen stations to feed the high-pressure H to
2
FCVs is expensive because of the use of large mechanical hy-
drogen compressors and/or the consumption of large amounts
of energy in the liquefaction of hydrogen followed by heating
2
2
À1
lies with its high turnover frequency (1800 h at 40 MPa) to
produce high-pressure H with a good lifetime of >40 h. Inter-
2
[
3]
estingly, only very low levels carbon monoxide (less than
to generate high-pressure gas. To overcome these problems,
6
1
volppm) were detected in the generated gas, even at
20 MPa.
effective high-pressure H tanks in a cryo-compressed state or
2
liquid state, metal hydrides, and physical H adsorption materi-
2
[
2a,4]
als have been developed for H storage system.
However,
2
these methods only allow a low weight density of H and con-
2
The increasing demand for energy, especially in the transporta-
tion sector, is diminishing fossil fuel resources and escalating
sume a lot of energy to maintain the high pressure for a long
[
2a,4b]
time and to release the stored H2.
Recently, some chemi-
environmental concerns. Hydrogen gas (H ) is considered to be
cals such as ammonia borane, N-ethyl hydrocarbazole, methyl
2
one of the promising alternative clean fuels to replace fossil
cyclohexane, hydrazine, methanol, formic acid (FA), and ammo-
nia have received attention as H storage chemicals as they
2
[
a] Dr. M. Iguchi, Prof. Dr. H. Kawanami
Research Institute for Chemical Process Technology
Department of Material and Chemistry
National Institute of Advanced Industrial
Science and Technology
provide significant advantages in terms of availability, recharg-
[2,4b,c]
ing, and safety.
Within these H storage chemicals, we fo-
2
cused on FA, because it is a low-toxicity, low-flammability, bio-
degradable liquid at ambient conditions, and has a compara-
tively high H content. Compared to the other H storage ma-
Sendai, 983-8551 (Japan)
E-mail: h-kawanami@aist.go.jp
2
2
terials, decomposition of FA has a low-reaction enthalpy; thus,
[
b] Dr. Y. Himeda
H can be produced from FA at mild temperatures, even at
2
Research Center for Photovoltaics
Department of Energy and Environment
National Institute of Advanced Industrial
Science and Technology
[
5]
<
1008C. In addition, FA decomposition is thermodynamically
favorable, so that the high-pressure H is generated easily from
2
FA in contrast to other H storage chemicals. Therefore, FA re-
2
Tsukuba, 305-8568 (Japan)
quires less energy for the H production and could be one of
2
[
c] Dr. Y. Manaka
the most attractive H2 storage chemicals. Moreover, FA can
Renewable Energy Research Center
Department of Energy and Environment
National Institute of Advanced Industrial Science and Technology
Fukushima, 963-0298 (Japan)
[
6]
function as a renewable material for H storage. Carbon diox-
2
ide (CO ), which is the co-product of FA decomposition, can be
2
hydrogenated back to FA in water or organic solvents on a cat-
alyst surface or in the presence of specific homogeneous cata-
[
d] Dr. K. Matsuoka
Research Institute of Energy Frontier
Department of Energy and Environment
National Institute of Advanced Industrial Science and Technology Tsukuba,
[7]
lysts. There is a possibility of the formation of carbon monox-
ide (CO) and water by the dehydration of FA as a side reaction
during FA decomposition, which could be fatal to fuel cells
3
05-8568 (Japan)
[
8]
[
e] Dr. M. Iguchi, Dr. Y. Himeda, Dr. Y. Manaka, Dr. K. Matsuoka,
Prof. Dr. H. Kawanami
due to facile catalyst poisoning by CO. As mentioned before,
in the presence of water, FA undergoes dehydrogenation and
Core Research for Evolutional Science and Technology,
Japan Science and Technology Agency
Tokyo, 102-0076 (Japan)
[9]
dehydration reactions, but both reactions remain unselective
in the aqueous phase. Therefore, to avoid dehydration to gen-
erate CO, it is necessary to use an effective catalyst for the de-
composition of FA at lower than 1008C. Many catalysts have
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201501296.
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been studied for the selective decomposition of FA to gener-
[10]
ate H2 with high efficiency.
Recently, we have developed
water-soluble iridium catalysts for the decomposition of FA at
[7b,11]
a temperature of <1008C.
In particular, the water-soluble
Ir catalyst, [Cp*Ir(4DHBP)(H O)][SO ] (Cp*=pentamethylcyclo-
2
4
pentadienide, 4DHBP=4,4’-dihydroxy-2,2’-bipyridine), was
shown to have a long lifetime (34 h) for decomposition of FA
[11a]
at atmospheric pressure.
Here, we have applied the same Ir catalyst ([Cp*Ir(4DHB-
P)(H O)][SO ]) for the decomposition of FA to generate high-
2
4
pressure gases (H and CO ) at >70 MPa without any forma-
2
2
tion of CO at temperatures below 1008C. Our target is the con-
tinuous generation of gas under high-pressure conditions re-
lated to its application for FCVs. Furthermore, we also success-
fully demonstrate a simple and effective method to separate
high-pressure H with 85% purity from the generated gases
2
(
H /CO =1:1) by changing the physical state of the product
2 2
mixture from the supercritical state to the gas–liquid state
while maintaining the high-pressure condition (Figure 1).
Figure 3. Time course of the generated pressure by the decomposition of
FA at various initial concentrations. The initial concentration of FA is as fol-
À1
À1
À1
lows: 4 molL (black plus), 10 molL (blue triangle), 15 molL (green
À1
cross), 20 molL (red circle). Reaction conditions: 808C, aqueous solution of
À1
À1
FA (4–20 molL , 13 mL), [Cp*Ir(4DHBP)(H
2
O)][SO
4
] (2.0 mmolL , 26 mmol).
À1
2
0 molL (Figure 3, red circles). The generated pressure of
1
23 MPa was much higher than the reported value of 75 MPa
[
10a]
Figure 1. Continuous, high-pressure H
2
production method involving the de-
+CO , followed by gas–
2
while maintaining a high-pressure condi-
at 908C in the presence of a ruthenium catalyst.
After 12 h,
composition of FA to generate high-pressure H
liquid separation to purify the H
tion.
2
2
the pressure stabilized at 123 MPa, and then remained con-
stant for a further few hours as the chemical equilibrium of the
decomposition of FA was attained. When the gas pressure
reached 123 MPa, 86 mol% of FA had been decomposed into
H and CO , with a high turnover number (TON) of 8600. We
Different reaction parameters to generate high-pressure hy-
drogen gas from the decomposition of FA were studied by
using a high-pressure reactor (Figure 2). Figure 3 shows the
time course of the generated gas pressure as a function of the
initial concentration of FA at a fixed temperature of 808C in
the presence of the Ir catalyst. The generated gas pressure
reached a maximum of 123 MPa within 12 h in the presence of
2
2
confirmed that the generated high-pressure gas consisted of
only H2 and CO , with a very small amount of CO (<
2
6 volppm), which is the detection limit of GC-mTCD (Support-
ing Information Figure S1(b)). Depending on the initial FA con-
À1
centrations of 4, 10, and 15 molL , the final equilibrium gas
pressure reached 26, 72, and 105 MPa within the reaction time
of 3, 4, and 7 h, respectively (Figure 3). The reaction was re-
2
6 mmol of catalyst when the initial FA concentration was
À1
peated 3 times with the same FA concentration of 15 molL ,
and it was confirmed that a final pressure of ꢀ105 MPa was
achieved (Supporting information: Table S2). From the results,
the final equilibrium gas pressures increase proportionally with
the initial concentration of FA (Supporting information: Fig-
ure S2). After reaching a constant pressure, the final conversion
of FA at each condition is constant (>85 mol%) even in the
high-pressure region (Supporting information: Table S2). There-
fore, a final equilibrium gas pressure of >120 MPa would be
available with a higher initial concentration of FA up to
À1
2
6 molL , which is 100 mol% of FA. We estimated by thermo-
dynamic considerations that FA could produce 225 MPa as the
final equilibrium pressure (Supporting information: Thermody-
namic considerations). Thus, decomposition of FA using the Ir
catalyst has huge advantages, as it can be used for the produc-
tion of high-pressure gas (H and CO ) at >120 MPa (up to
Figure 2. Schematic diagram of the apparatus for monitoring the pressure
evolution during the catalytic decomposition of FA: a) high-pressure reactor
made of 316 stainless steel, b) stop valve or back-pressure regulator, c) gas
chromatography, d) flow meter. Pressure and temperature are recorded at
T1–T3 and p1–p2, respectively.
2
2
2
25 MPa) without formation of CO, which is sufficient to feed
FCVs that operate at 70 MPa.
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The feeding rate of gas under high-pressure conditions was
also studied for the catalytic decomposition of FA by using the
high-pressure reactor (Figure 2). In consideration of the fact
that a FCV may need to be fed H at 35 MPa in the future, ini-
2
tially the reaction was carried out 40 MPa at 808C with
À1
À1
1
2 molL
of aqueous FA and 0.2 mmolL
of catalyst
(
Figure 4). When the pressure reached the desired pressure of
Figure 5. Pressure dependence of the conversion rate of FA at various pres-
sures: atmospheric pressure (blue triangle), 10 MPa (green cross), 30 MPa
À1
(
3
red circle). Reaction conditions: 808C, aqueous solution of FA (8 molL
,
À1
0–40 mL), [Cp*Ir(4DHBP)(H
2
O)][SO
4
] (0.2 mmolL , 6–8 mmol). Time is de-
fined as the time after reaching each pressure of the generated gas at 0.1,
0, and 30 MPa, respectively. The conversion of FA is calculated from the
1
generated gas volume.
Figure 4. Time course of the gas volume and the generated pressure from
FA decomposition: gas volume (red circle), generated pressure (blue cross),
pressure, so that the initial FA conversion increased with the
pressure at 0.1, 10, and 30 MPa, respectively, in Figure 5. When
the applied pressure was in the atmospheric condition
À1
initial generated gas rate of 0.67 Lh (black line). Reaction conditions: 808C,
À1
4
(
0 MPa, aqueous solution of FA (12 molL , 40 mL), [Cp*Ir(4DHBP)(H
2
O)][SO
4
]
À1
0.2 mmolL , 8 mmol). The rate of gas evolution was averaged for the initial
À1
1
h.
(0.1 MPa), the initial TOF was 9100 h (Figure 5, blue triangle),
[
11a]
which corresponds well with previous work.
When the pres-
sure was increased to 10 MPa (Figure 5, green cross) and
30 MPa (Figure 5 red circle), the decomposition rate of FA de-
creased. As a result, TOF values at 10 and 30 MPa decreased to
4
0 MPa, the conversion of FA was estimated as 54 mol% and
À1
the concentration of FA was 5.4 molL based on the total
volume of decomposition. After the pressure reached 40 MPa,
a constant volume of high-pressure gas was exhausted
through a back-pressure regulator, and the final FA concentra-
À1
À1
around 2/3 (5700 h ) and 1/4 (2500 h ), respectively, com-
pared to that at atmospheric pressure.
By the above-mentioned method from the decomposition
À1
tion after 6 h was 3.8 molL . For the first 1 h after the evolu-
of FA, we can generate high-pressure H gas without any com-
2
tion of gas started at 40 MPa, the average gas generation rate
pressing procedures, but the generated gas would require pu-
rification for use in future FCVs. Hence, to avoid the consump-
tion of compression energy, the development of a purification
process under high-pressure conditions is necessary. For the
purification under high-pressure conditions, we applied the
gas–liquid phase separation method, simply by changing the
physical fluid state (Figure 6 and Table 1). The high-pressure
gas at >7.4 MPa, which is generated from FA as a mixture of
H and CO at 808C, has a lower critical point than CO itself
À1
was 0.67 Lh and even under the milder conditions, the turn-
À1
over frequency (TOF) obtained was 1800 h , which is signifi-
À1
cantly higher than 670 h using a ruthenium catalyst (5–
[13]
2
5 MPa, and 1208C) as reported in the literature. The gas
evolution rate was constant for 2–3 h in the beginning, and
then gradually decreased with time (Supporting Information:
Figure S3). The decrease in the FA decomposition rate with
[
11a]
time is attributed to a decrease in the FA concentration.
Ac-
2
2
2
[
14]
cording to GC-mTCD analysis of the generated gas, an equimo-
(31.18C, 7.4 MPa). Therefore, the generated gas is in the su-
lar mixture of H and CO gases are generated during the gas
percritical phase. Thus, to purify H gas from the gas mixture,
2
2
2
evolution for 6 h, with a high TON of >41000, and very low
levels of CO being detected (<6 volppm, see Supporting infor-
mation: Figure S1(c)). Therefore, the catalyst can maintain high
selectivity for the FA decomposition even at in the high-pres-
sure region and the long lifetime indicates that the process is
free from catalyst poisoning. We also studied the pressure ef-
fects on the decomposition rate of FA (Figure 5). A further
amount of the generated gas was required to reach the higher
the gas separator was simply cooled down to a temperature
below the critical temperature in order to change the generat-
ed gas from the supercritical state to the gas–liquid state with-
out depressurization. When the generated gas entered the gas
separator at 808C and 30 MPa of pressure, the gas separator
was set at 358C, which is the supercritical condition at 30 MPa.
The equimolar mixture of H and CO gases were obtained
2
2
from the back-pressure regulator attached to the separator.
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Figure 6. Schematic diagram of the apparatus for the kinetic studies on the catalytic decomposition of FA: a) reactor, b) separator, c) backpressure regulator,
d) gas chromatography, and e) flow meter. Pressure and temperature are recorded at T1–T4 and p1–p2, respectively.
rich liquid phase (Figure 7c). As shown in Table 1, the amount
Table 1. Gas contents of the separated gas generated from the decom-
position of FA at various temperatures of the separator at 30 MPa.
of H in the gas phase increased as the separator temperature
2
[a]
was set to lower temperatures, and no CO was detected in the
H -rich gas phase for the first 6 h. At À518C, 85 mol% of H
2
2
Entry Separator X 2
H
X
CO
Initial gas
Initial H
2
À1 [b]
À1 [c]
temp. [8C] [mol%] [mol%] flow [Lh
]
production [h
]
gas at 30 MPa was obtained with a good TOF value. We also
[
d]
estimated the vapor–liquid equilibrium value of the H and
2
1
2
3
4
5
35
0
À15
À40
À51
51
58
69
80
85
n.d.
n.d.
n.d.
n.d.
n.d.
0.93
0.86
0.75
0.73
0.69
2560
2620
2790
3030
3050
CO system (Supporting Information: Figure S5), which shows
2
that it is possible to obtain 93 mol% of purified H gas at
2
3
0 MPa and À518C. Therefore, further improvement of the
separation process to achieve highly purified H gas would be
2
[
a] Gas generation condition: 808C, 30 MPa. Gas separation condition:
possible by allowing the gas mixture to cool down enough
during the transfer from the reaction vessel to the separation
vessel, and retaining it inside the separator for sufficient time
to reach equilibrium. Finally, we found the initial gas flow rate
decreases with a decrease in the separator temperature
À1
À51–358C, 30 MPa. Aqueous solution of FA: 8 molL , 40 mL, catalyst
À1
(
[Cp*Ir(4DHBP)(H
2
O)][SO
4
]): 0.2 mmolL , 7–8 mmol. [b] Average gas rate
for initial 1 hour. [c] Average rate of H
d] Not detected (less than 6 volppm).
2
gas per mole of the catalyst.
[
(
Table 1). As the separator temperature was set to lower tem-
The temperature of the separator was then changed to À158C
peratures, a further amount of the generated gas was required
and 69 mol% of H gas was obtained. The temperature was
to maintain the pressure because of liquefied CO in the sepa-
2
2
further changed to À518C and 85 mol% of H gas was ob-
rator. As a result, the conversion of FA increases to reach the
pressure with a decrease in the separator temperature (Sup-
porting information: Figure S6). After completion of the reac-
tion, 92–93 mol% of FA was converted and a TON of 37000–
38000 was achieved at the different separator temperatures
(Supporting information: Table S3).
2
tained at 30 MPa. To confirm these results, we observed the
phase behavior through the sapphire windows attached to the
high-pressure separation vessel (Figure 7). At 30 MPa and
3
58C, there was a single homogeneous phase as well as at-
mospheric pressure (Figures 7a,b). As the temperature was
lowered to À108C, the homogeneous phase separated into
two phases comprised of the H -rich gas phase and the CO -
In conclusion, we have developed a simple and continuous
high-pressure hydrogen gas (>120 MPa) production system
2
2
Figure 7. Phase behaviour of the gas generated from FA decomposition, observed in the gas separator under various conditions: a) 0.1 MPa and 358C,
À1
b) 30 MPa and 358C, c) 30 MPa and À108C. Generation condition (808C, 30 MPa), aqueous solution of FA (12 molL , 40 mL), [Cp*Ir(4DHBP)(H
2 4
O)][SO ]
À1
(
0.2 mmolL , 8 mmol). The black vertical tube in the view cell is the inlet tube of the generated gas.
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from FA decomposition catalyzed by the water-soluble homo-
geneous Ir catalyst, [Cp*Ir(4DHBP)(H O)][SO ], without any
[2] a) N. Armaroli, V. Balzani, ChemSusChem 2011, 4, 21–36; b) D. Teich-
mann, W. Arlt, P. Wasserscheid, R. Freymann, Energy Environ. Sci. 2011,
2
4
4, 2767–2773.
compressing procedures. The system can generate high-pres-
sure gas, which is enough to feed FCVs (70 MPa). We further
successfully demonstrated high-pressure H2 gas separation
from the generated gas simply by cooling the gas to change
the supercritical state to the gas–liquid state. The system can
[
3] J. Alazemi, J. Andrews, Renewable Sustainable Energy Rev. 2015, 48,
483–499.
[4] a) L. Schlapbach, A. Zuttel, Nature 2001, 414, 353–358; b) U. Eberle, M.
Felderhoff, F. Schüth, Angew. Chem. Int. Ed. 2009, 48, 6608–6630;
Angew. Chem. 2009, 121, 6732–6757; c) A. F. Dalebrook, W. Gan, M. Gra-
semann, S. Moret, G. Laurenczy, Chem. Commun. 2013, 49, 8735–8751.
[5] K. C. Ott, “Final report for the DOE chemical hydrogen storage center of
excellence”, can be found under http://energy.gov/sites/prod/files/
generate hydrogen gas continuously with a high rate (TOF=
À1
2
500 h at 30 MPa) even at a mild temperature of 808C. In ad-
2
014/03/f11/chemical_hydrogen_storage_coe_final_report.pdf, 2012.
6] a) R. Williams, R. S. Crandall, A. Bloom, Appl. Phys. Lett. 1978, 33, 381–
83; b) S. Enthaler, J. von Langermann, T. Schmidt, Energy Environ. Sci.
dition, >85% of FA is converted to the gas mixture of H and
2
[
CO , and the CO side product was below the fatal catalyst poi-
2
3
soning level as confirmed from the long catalyst lifetime even
at 120 MPa pressure. This system has the potential to be devel-
oped further and can be used as a simple and easy to handle
2010, 3, 1207–1217; c) M. Grasemann, G. Laurenczy, Energy Environ. Sci.
2012, 5, 8171–8181.
7] a) Y. Inoue, H. Izumida, Y. Sasaki, H. Hashimoto, Chem. Lett. 1976, 5,
[
863–864; b) J. F. Hull, Y. Himeda, W.-H. Wang, B. Hashiguchi, R. Periana,
system for the generation of high-pressure H , not only for
2
D. J. Szalda, J. T. Muckerman, E. Fujita, Nat. Chem. 2012, 4, 383–388;
c) S. Moret, P. J. Dyson, G. Laurenczy, Nat. Commun. 2014, 5, 4017.
8] D. L. Trimm, Appl. Catal. A 2005, 296, 1–11.
FCVs, but also for other applications.
[
[
9] a) H.-T. Chen, J.-G. Chang, H.-L. Chen, J. Phys. Chem. A 2008, 112, 8093–
8
099; b) S. Inaba, J. Phys. Chem. A 2014, 118, 3026–3038.
Experimental Section
[
10] a) C. Fellay, P. J. Dyson, G. Laurenczy, Angew. Chem. Int. Ed. 2008, 47,
3966–3968; Angew. Chem. 2008, 120, 4030–4032; b) S. Fukuzumi, T. Ko-
bayashi, T. Suenobu, ChemSusChem 2008, 1, 827–834; c) B. Loges, A.
Boddien, H. Junge, M. Beller, Angew. Chem. Int. Ed. 2008, 47, 3962–
The general kinetic studies on the catalytic decomposition of FA
are as follows. The experiments used the apparatus shown in
Figure 3. The Ir catalyst (6–8 mmol) and the aqueous FA solution
3
965; Angew. Chem. 2008, 120, 4026–4029; d) M. Ojeda, E. Iglesia,
Angew. Chem. Int. Ed. 2009, 48, 4800–4803; Angew. Chem. 2009, 121,
894–4897; e) A. Boddien, D. Mellmann, F. Gärtner, R. Jackstell, H.
Junge, P. J. Dyson, G. Laurenczy, R. Ludwig, M. Beller, Science 2011, 333,
733–1736; f) K. Tedsree, T. Li, S. Jones, C. W. A. Chan, K. M. K. Yu, P. A. J.
Bagot, E. A. Marquis, G. D. W. Smith, S. C. E. Tsang, Nat. Nanotechnol.
011, 6, 302–307; g) Q.-Y. Bi, X.-L. Du, Y.-M. Liu, Y. Cao, H.-Y. He, K.-N.
Fan, J. Am. Chem. Soc. 2012, 134, 8926–8933.
(
30–40 mL) were introduced into the reactor, and then the appara-
tus was purged of air with argon. The reactor was heated to 808C
and the separator was set to the desired temperature. After com-
pleting the reaction, the reactor was cooled and then depressur-
ized to atmospheric pressure carefully. The gas was collected
during the depressurization and the reaction solution was analyzed
by HPLC-UV. Further experimental details are provided in the sup-
porting information.
4
1
2
[11] a) Y. Himeda, Green Chem. 2009, 11, 2018–2022; b) Y. Himeda, S. Miyaza-
wa, T. Hirose, ChemSusChem 2011, 4, 487–493; c) W.-H. Wang, J. F. Hull,
J. T. Muckerman, E. Fujita, T. Hirose, Y. Himeda, Chem. Eur. J. 2012, 18,
9
397–9404; d) Y. Manaka, W.-H. Wang, Y. Suna, H. Kambayashi, J. T.
Acknowledgements
Muckerman, E. Fujita, Y. Himeda, Catal. Sci. Technol. 2014, 4, 34–37; e) Y.
Suna, M. Z. Ertem, W.-H. Wang, H. Kambayashi, Y. Manaka, J. T. Mucker-
man, E. Fujita, Y. Himeda, Organometallics 2014, 33, 6519–6530; f) W.-H.
Wang, S. Xu, Y. Manaka, Y. Suna, H. Kambayashi, J. T. Muckerman, E.
Fujita, Y. Himeda, ChemSusChem 2014, 7, 1976–1983; g) N. Onishi, S.
Xu, Y. Manaka, Y. Suna, W. H. Wang, J. T. Muckerman, E. Fujita, Y. Himeda,
Inorg. Chem. 2015, 54, 5114–5123.
The research is financially supported by Core Research for Evolu-
tional Science and Technology, CREST, JST. H.K. and M.I. thank Dr.
Maya Chatterjee for useful discussions and Dr. David Grills of
Brookhaven National Laboratory for help with manuscript prepa-
ration.
[
[
12] K. Sordakis, M. Beller, G. Laurenczy, ChemCatChem 2014, 6, 96–99.
13] C. Fellay, N. Yan, P. J. Dyson, G. Laurenczy, Chem. Eur. J. 2009, 15, 3752–
3
760.
Keywords: decomposition
·
formic acid
·
gas–liquid
[
14] C. Y. Tsang, W. B. Street, Chem. Eng. Sci. 1981, 36, 993–1000.
separation · high-pressure hydrogen · iridium catalyst
Received: November 24, 2015
[
1] L. Schlapbach, Nature 2009, 460, 809–811.
Published online on December 10, 2015
ChemCatChem 2016, 8, 886 – 890
www.chemcatchem.org
890
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