Carbon Dioxide-Free Hydrogen Production with Integrated Hydrogen Separation and Storage

Article abstract of DOI:10.1002/cssc.201600435

An integration of CO₂-free hydrogen generation through methane decomposition coupled with hydrogen/methane separation and chemical hydrogen storage through liquid organic hydrogen carrier (LOHC) systems is demonstrated. A potential, very interesting application is the upgrading of stranded gas, for example, gas from a remote gas field or associated gas from off-shore oil drilling. Stranded gas can be effectively converted in a catalytic process by methane decomposition into solid carbon and a hydrogen/methane mixture that can be directly fed to a hydrogenation unit to load a LOHC with hydrogen. This allows for a straight-forward separation of hydrogen from CH₄and conversion of hydrogen to a hydrogen-rich LOHC material. Both, the hydrogen-rich LOHC material and the generated carbon on metal can easily be transported to destinations of further industrial use by established transport systems, like ships or trucks.

Full text of DOI:10.1002/cssc.201600435

DOI: 10.1002/cssc.201600435
Concepts
Carbon Dioxide-Free Hydrogen Production with Integrated
Hydrogen Separation and Storage
Stefan Dꢀrr,[a] Michael Mꢀller,[a] Holger Jorschick,[b] Marta Helmin,[c] Andreas Bçsmann,[a]
Regina Palkovits,*[c] and Peter Wasserscheid*[a, b]
An integration of CO2-free hydrogen generation through meth-
ane decomposition coupled with hydrogen/methane separa-
tion and chemical hydrogen storage through liquid organic hy-
drogen carrier (LOHC) systems is demonstrated. A potential,
very interesting application is the upgrading of stranded gas,
for example, gas from a remote gas field or associated gas
from off-shore oil drilling. Stranded gas can be effectively con-
verted in a catalytic process by methane decomposition into
solid carbon and a hydrogen/methane mixture that can be di-
rectly fed to a hydrogenation unit to load a LOHC with hydro-
gen. This allows for a straight-forward separation of hydrogen
from CH4 and conversion of hydrogen to a hydrogen-rich
LOHC material. Both, the hydrogen-rich LOHC material and the
generated carbon on metal can easily be transported to desti-
nations of further industrial use by established transport sys-
tems, like ships or trucks.
Introduction
Today, more than 60 million tons of hydrogen are produced
and utilized industrially.[1] The largest part of this quantity is ap-
plied in the petrochemical and chemical industry, mainly for
desulphurization of fuels and hydrogenation reactions, for ex-
ample, the production of ammonia and methanol.[2] In the
near future, hydrogen is expected to gain additional impor-
tance as a green energy vector for the mobility sector, because
its combustion in fuel cells or combustion engines produces
water as the only combustion product.[3,4]
to the stoichiometry of the methane reforming and water-gas
shift reactions, the energy consumption of the process, and
the molecular masses of the molecules involved.[5]
Aiming for the sustainable (zero emission) production of hy-
drogen, electrolysis of water using renewables is one possible
option. However, electrolysis is still relatively expensive (3 E
per kg of hydrogen).[6] As an alternative, hydrogen production
from hydrocarbons avoiding CO2 emissions can be considered.
Whereas CO2 capture and storage (CCS technology) is energy
and cost intensive,[7] and associated with ecological uncertain-
ties, hydrogen production through catalytic decomposition of
hydrocarbons linked to elemental carbon sequestration is
a promising option. In particular, the moderately endothermic
catalytic methane decomposition to carbon and hydrogen
holds great promise for the sustainable production of hydro-
gen.[8]
However, to consider hydrogen as a sustainable fuel, it is im-
portant to assure that its production is free of CO2 emissions.
This is not a trivial task given that 95% of today’s industrial hy-
drogen production is generated from fossil fuels by steam re-
forming, partial oxidation, or gasification processes. All of
these produce significant amounts of CO2. For example, 1 ton
of hydrogen produced by using methane as raw material was
reported to produce more than 10 tons of CO2 simply owing
CH4 ! C þ 2 H2 DH25 ꢀC ¼ 74:5 kJ molꢁ1
ð1Þ
[a] S. Dꢀrr, M. Mꢀller, A. Bçsmann, Prof. P. Wasserscheid
Lehrstuhl fꢀr Chemische Reaktionstechnik
Whereas purely thermal decomposition of methane occurs
at process temperatures above 12008C,[9] the use of an appro-
priate catalyst has been reported to bring the operating tem-
perature down to 5508C.[10] Regarding suitable catalysts for
catalytic methane decomposition (CMD), the literature pays
special attention to supported group 8–10 base metal cata-
lysts, in particular nickel, iron, and cobalt.[11] While nickel cata-
lysts are limited in CMD to operating temperatures below
7008C, iron systems have been reported to operate even
above this temperature.[11] Despite these differences, any cata-
lyst used for CMD eventually deactivates as result of deposition
of carbon-rich polyaromatic structures, amorphous, filamen-
tous, or graphitic carbon on its surface.
Friedrich-Alexander-Universitꢁt Erlangen-Nꢀrnberg
Egerlandstr. 3, 91058 Erlangen (Germany)
[b] H. Jorschick, Prof. P. Wasserscheid
Helmholtz-Institut Erlangen-Nꢀrnberg fꢀr Erneuerbare Energien (IEK-11)
Forschungszentrum Jꢀlich GmbH
Egerlandstraße 3, 91058 Erlangen (Germany)
E-mail: p.wasserscheid@fz-juelich.de
[c] M. Helmin, Prof. R. Palkovits
Lehrstuhl fꢀr Heterogene Katalyse und Technische Chemie
RWTH Aachen and JARA Energy
Worringerweg 2, 52074 Aachen (Germany)
E-mail: palkovits@itmc.rwth-aachen.de
Supporting Information and the ORCID identification number(s) for the
author(s) of this article can be found under http://dx.doi.org/10.1002/
cssc.201600435.
CMD is a complex process that can be divided into three
key steps: (i) hydrogen generation by a sequence of methane
adsorption and dissociation at the metal surface and simulta-
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neous desorption of hydrogen; (ii) formation of carbon nano-
materials by dissolution of chemisorbed carbon atoms into the
metal followed by diffusion of carbon through the bulk of the
metal where carbon atoms precipitate onto the support form-
ing the nanostructure; and (iii) catalyst deactivation caused by
slower and slower carbon diffusion through the metal particle
and formation of graphitic carbon at the particle surface thus
reducing the active surface area.[12] Figure 1 illustrates these
three steps.
by an extremely low volumetric energy density (only 3 WhLꢁ1
at ambient pressure), and its transport over long distances is
unsuitable in elemental form. Even the transport of com-
pressed gaseous hydrogen (CGH2, typically up to 700 bar
ꢂ79 MPa pressure) or liquefied cryogenic hydrogen (LH2, typi-
cally at ꢁ2538C), would not solve the problem of an efficient
transport of elemental hydrogen, as the volumetric storage
density is still modest (see Table 1). Moreover, hydrogen com-
pression and cooling come along with additional energy con-
sumption and require special infrastructure, such as compres-
sor stations, compressed gas tankers, or transport vehicles with
cryogenic tank systems.
Table 1. Volumetric and gravimetric energy density of elemental hydro-
gen compared to fossil fuels.[16]
Energy source
Fossil fuels
Energy carrier
Energy density
Energy density
[kWhLꢁ1
]
[kWhkgꢁ1
]
Gasoline
Diesel
Heavy oil
Natural gas
H2 (atm)
GCH2 (700 bar)
LH2 (liquid)
LOHC (H18-DBT)
8.6
9.8
10.7
2.4
0.003
1.3
2.4
11.4
11.8
11.0
11.1
33.0
33.0
33.0
2.05
Hydrogen
1.87
Figure 1. Representation of hydrogen production, carbon nanomaterial
(CNM) formation, and growth in the CMD process.
A significant part of the world’s methane reserves is located
far from industrial and population centers, and transportation
cost hinders its efficient utilization. Moreover, many of these
gas fields are far too small to justify chemical conversion of
methane by current gas-to-liquid technologies that gain eco-
nomic attractiveness only in the form of world-scale units.[13]
Thus, the term “stranded gas” refers to methane resources
at places and in quantities that do not justify the installation of
pipeline infrastructures, for example, associated gas from an
off-shore oil drilling rig or from oil drilling at remote locations
in the desert. Currently, such stranded gas is typically flared,
vented or re-injected.[14] Consequently, new technologies able
to convert this gas in small facilities of low investment cost di-
rectly at the gas source would benefit from a very low or even
negative feedstock price. It is common understanding among
experts that the amount of stranded gas is on the order 40 to
60% of the proven global natural gas resources.[15]
In this contribution, we propose the combination of CMD
with hydrogen storage in liquid organic hydrogen carrier
(LOHC) systems as a very attractive option to overcome the
named limitations and to establish a technology to upgrade
stranded methane in the form of storable and transportable
hydrogen equivalents ready for industrial use at any far distant
location. LOHC systems are composed of pairs of hydrogen-
lean, mostly aromatic compounds and hydrogen-rich, mostly
alicyclic compounds. By reversible hydrogenation and subse-
quent dehydrogenation, LOHCs can be used to safely bind,
store, transport, and release hydrogen on demand.[17–20] De-
pending on the LOHC system, hydrogen storage is possible at
a material-based energy density of up to 72 gH LLOHC or
2
2.4 kWhLꢁ1. Thus, the concept allows hydrogen storage over
long times at high volumetric energy densities as well as hy-
drogen transport over long distances without losses using ex-
isting infrastructure for liquid fuels (e.g., ships, trucks, rail
trucks, and tank farms). Figure 2 shows the proposed combina-
tion of CMD and hydrogen storage through LOHC systems.
Herein, we demonstrate new insight into the combination of
CMD and LOHC hydrogenation by using representative hydro-
gen-methane mixtures from CMD as substrate for charging
a selected, suitable LOHC system.
CMD is, in principle, ideally suited for a treatment of strand-
ed methane. Compared to common gas-to-liquid technology,
CMD represents a relatively simple one-step process that con-
verts methane directly into two valuable products, hydrogen
and carbon-loaded metal. However, two aspects prevent the
use of CMD as economic option in stranded gas upgrading:
(i) for thermodynamic reasons, the CMD process provides no
full methane conversion in the desired temperature range of
its catalytic operation, and hydrogen–methane separation is re-
quired to recycle unconverted methane back into the CMD
process and to obtain pure hydrogen; and (ii) whereas carbon-
loaded metal can be easily shipped from the remote place to
a potential consumer, the produced hydrogen is characterized
Hydrogen production through CMD
The influence of the reaction temperature on hydrogen yield
in CMD was studied using a 20 wt% Ni/Al2O3 catalyst in the
temperature range of 550 to 7008C. Figure 3 shows the outlet
hydrogen stream as well as methane conversion as a function
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Figure 2. The proposed two-step upgrading process for stranded gas: meth-
ane is converted in a catalytic decomposition process to carbon and hydro-
gen, which is subsequent purified from remaining methane and transferred
into a transportable form by LOHC hydrogenation.
Figure 4. TEM micrographs of the spent Ni/Al2O3 catalyst at (a,b) 6008C and
at (c,d) 7008C.
ical differences of the deposited carbon as a function of differ-
ent reaction temperatures. Figure 4a–d show some representa-
tive TEM micrographs of the spent catalyst at 600 (Figure 4a,b)
and 7008C (Figure 4c,d). The TEM measurements reveal the
presence of carbon material on the catalyst surface, which is
mainly deposited in the form of nanostructures with varying
morphology depending on the reaction temperature. Compar-
ing the nanostructures formed at 6008C with those formed at
7008C, the material obtained at 6008C consists mainly of
hollow cylindrical filaments emerging from the nickel particles
(Figure 4a) coexisting with filaments containing a metal parti-
cle on their tip, which is uniformly coated with parallel planes
of graphene (Figure 4b). An examination of the TEM measure-
ments evidences that long filaments with no particle on their
tip are more abundant than filaments with uniform coatings.
In contrast, carbon material formed at a reaction temperature
of 7008C shows a less homogenous morphology distribution.
Nanotubes with coated metal particles on their tip (Figure 4c),
uniformly coated nickel particles referred to as nano-onions, as
well as bamboo shaped filaments (Figure 4d) were obtained
during this reaction. The results suggest, that high tempera-
tures cause fast catalyst deactivation owing to the immediate
formation of a graphitic layer encapsulating the catalytically
active metal particle. In contrast, the catalyst maintains its ac-
tivity owing to the generation of nanotubes at lower reaction
temperatures.
Figure 3. Effect of reaction temperature on the evolution of hydrogen from
methane by CMD at a gas hourly space velocity (GHSV) of 12500 hꢁ1; left
axis (black symbols) shows the generated volumetric hydrogen flow; right
axis (red symbols) shows the degree of methane conversion.
of reaction time. The nickel catalyst maintains its initial activity
at a reaction temperature of 5508C for the reaction time of 5 h
producing
54 mLN min
a
constant hydrogen outlet stream of
ꢁ1
ꢁ1
g
(where LN refers to the volume at normal
cat
conditions: 1 bar, room temperature) corresponding to a meth-
ane conversion of 14%. A slight increase in reaction tempera-
ture of 508C resulted in
a hydrogen outlet stream of
ꢁ1
92 mLN min
g
ꢁ1. However, the catalyst experienced slight
cat
deactivation at 6008C during the reaction time of 5 h; there-
fore, a loss in methane conversion of around 5% was observed
during this time. Further increase in reaction temperature re-
sulted in an increase of the initial hydrogen yield to
Hydrogen separation and storage through LOHC hydroge-
nation
ꢁ1
ꢁ1
122 mLN min
g
at 7008C. However, at this temperature
cat
the evolving hydrogen content dropped quickly until complete
catalyst deactivation after approximately 1.5 h on stream.
The observed fast deactivation behavior of Ni/Al2O3 at
7008C can be attributed to the formation of different carbon
species during methane decomposition. TEM characterization
of the spent catalyst gave us more insight into the morpholog-
The LOHC hydrogen storage technology is based on reversible
hydrogenation of double bonds. In the past, various com-
pounds have been investigated for their suitability as LOHC
systems ranging from small aromatics, for example, benzene/
cyclohexane[21] and toluene/methylcyclohexane,[22–26] to con-
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R
R
densated aromatics (e.g., naphtaline/decalin[27,28]
)
and
t
t0
t
t0
nH ;reaction ðtÞ dt
nH ;reaction ðtÞ dt
2
2
ð2Þ
DoH ðtÞ ¼
¼
N-containing aromatics [e.g., N-ethyl-carbazole(NEC)/dedecahy-
dro-N-ethyl-carbazole[29–33]]. All the named systems have their
advantages and disadvantages regarding hydrogen capacity,
hydrogenation enthalpy, thermal stability liquid range, toxicity,
and technical availability.
n
9 ꢃ nH0ꢁDBT
H2;max
In Equation (2), nH ,reaction(t) represents the amount of hydro-
2
gen consumed at time t as measured by mass-flow-meter.
nH0ꢁDBT was calculated from mH0ꢁDBT, the mass of H0-DBT pro-
vided in the reactor.
An excellent tradeoff of all these highly relevant properties
for suitable LOHC materials is found for the relatively recently
reported system dibenzyltoluene (H0-DBT)/perhydrodibenzyl-
toluene (H18-DBT).[34–36] Dibenzyltoluene is a commercial heat
transfer oil (marketed under the tradenames Marlotherm SHꢁ
or Farolin WF0801ꢁ; price is below 4 Ekgꢁ1 on ton-scale) with
known and very favorable toxicology (non-toxic, non-mutagen-
ic, non-carcinogenic, not labelled as hazardous good in trans-
portation), high thermal stability, and excellent physico-chemi-
cal properties for many LOHC applications. The isomeric mix-
ture of dibenzyltoluenes has a melting point of ꢁ348C and
a boiling point of 3908C.[36] During hydrogenation, H0-DBT
binds 6.2 wt% hydrogen corresponding to an energy content
of 2.05 kWhkgꢁ1. Figure 5 shows a depiction of the H0-DBT/
H18-DBT hydrogen storage system.
In the here reported batch mode experiments, hydrogena-
tion is characterized by a constant reaction rate at the begin-
ning of the reaction, that is, for low to medium degrees of hy-
drogenation. The gradient of DoH versus time is almost con-
stant until a DoH of 0.6. This observation is further confirmed
by the constant hydrogen consumption, as shown in Figure 6.
This zero-order-like behavior hints for the fact that transport of
hydrogen gas into the liquid phase limits the observed macro-
kinetics during the period of maximum hydrogen consumption
at the beginning of the reaction. Further hydrogenation
beyond the DoH of 0.6 is significantly slower owing to the fall-
ing concentration of hydrogenable LOHC left, but full conver-
sion is always reached. The time to full conversion is a function
of hydrogen pressure, reaction temperature, stirrer speed, and
the molar catalyst to LOHC ratio.
The effect of hydrogen pressure on the rate of H0-DBT hy-
drogenation is shown in Figure 6 for experiments conducted
at 1808C and a molar catalyst to LOHC ratio of 1:400, corre-
sponding to 0.25 mol% of the applied, commercial Ru/Al2O3
(5 wt%ruthenium) catalyst. It is apparent that a higher hydro-
gen pressure leads to faster hydrogenation and complete for-
mation of H18-DBT is achieved in a shorter time. Full conver-
sion is reached after 100 min (50 barꢂ5 MPa), 140 min (40 bar
ꢂ4 MPa) or about 3 h at 30 bar hydrogen pressure. A reduc-
tion of hydrogen pressure below 30 bar leads to a massive in-
crease in reaction time for full DoH under otherwise identical
reaction conditions.
Figure 5. Storage and transport of hydrogen by reversible catalytic hydroge-
nation/dehydrogenation of dibenzyltoluene/perhydro-dibenzyltoluene.
As can be seen in Figure 7, a linear relation between pres-
sure and reaction rate is found for hydrogen pressures varying
from 5 to 50 bar (0.5–5 MPa). Further investigations of hydro-
genation reactions applying hydrogen pressures of less than
5 barꢂ0.5 MPa not only show poor reaction rates but also
seem to be affected by equilibrium limitations.
As shown by the recent studies of Brꢀckner et al.,[34] com-
plete hydrogen release from H18-DBT is possible by a catalytic,
endothermic dehydrogenation reaction, for example, in the
presence of Pt on alumina catalysts. These studies could also
show that dehydrogenation of H18-DBT proceeds under ap-
propriate conditions (i.e., 3108C, 1 barꢂ0.1 MPa) with negligi-
ble fragmentation of the hydrogen carrier molecule. This ena-
bles the utilization of the H0-DBT/H18-DBT LOHC system in re-
peated hydrogenation-dehydrogenation cycles. Due to these
very favorable properties we will restrict ourselves in this publi-
cation to the catalytic hydrogenation of H0-DBT as most inter-
esting way to purify and store hydrogen from the CMD pro-
cess.
The hydrogenation of H0-DBT comprises the consecutive hy-
drogenation of three isolated phenyl rings. For a quantitative
comparison, the degree of hydrogenation (DoH) is defined as
the ratio of the bound hydrogen and the maximum hydrogen
up-take capacity. For the experiments reported here dealing
with the hydrogenation of H0-DBT with hydrogen/methane
mixtures using a batch reactor, the DoH has been determined
by mass flow measurements according to Equation (2) and in-
dependently by 1H NMR spectroscopy.[37]
Figure 6. Hydrogenation of H0-DBT at different hydrogen pressures;
T=1808C, 5.9 mol DBT, 0.25 mol% Ru applied as 5 wt% Ru on Al2O3.
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from 700 rpm (standard reaction conditions) to 900 or
1100 rpm, led to a linear increase of hydrogen consumption at
the beginning of the hydrogenation (see the Supporting Infor-
mation for details). This confirms the hypothesis that hydrogen
gas mass transport into the liquid phase limits the observed
reaction rate under the applied conditions. Moreover, it indi-
cates that the increased rate in presence of methane gas is re-
lated to a faster mass transfer of hydrogen into the liquid
phase very probably owing to a lower viscosity of the meth-
ane-saturated LOHC mixture compared to the methane-free
system.
Conclusions
Our contribution highlights the fact that a combination of cat-
alytic methane decomposition (CMD) and hydrogen purifica-
tion and storage by hydrogenation of LOHC systems offers
a versatile, economically attractive, and new way for upgrading
stranded gas towards green, CO2-free hydrogen production.
Whereas the CMD step has been shown to operate in
steady-state for at least 5 h converting 14% of the offered
methane into hydrogen and carbon, the LOHC charging step
operates beneficially with diluted hydrogen/methane streams
to hydrogenate dibenzyltoluene to perhydro-dibenzyltoluene.
In the scenario of a stranded gas resource, for example, at
an off-shore oil platform or at a remote drilling site in the
desert, methane would be converted in the proposed technol-
ogy sequence into carbon rich metal (for metallurgic process-
es) and transportable hydrogen in the form of a hydrogen-rich
organic liquid.
Figure 7. Effect of hydrogen pressure on hydrogenation of H0-DBT;
T=1808C, 5.9 mol DBT, 0.25 mol% Ru applied as 5 wt% Ru on Al2O3, 3 h re-
action time.
To evaluate whether H0-DBT hydrogenation is a suitable
method to purify hydrogen from hydrogen/methane mixtures
out of the CMD process, our next set of experiments was dedi-
cated to batch reactor hydrogenation studies using hydrogen/
methane mixtures. As shown in Figure 8, no negative impact
of methane on the reaction rate or H0-DBT conversion was ob-
served for comparative experiments in which 20 barꢂ2 MPa of
methane were added to 40 barꢂ2 MPa of hydrogen. During
these runs (pH =40 bar, pCH =20 bar) even a remarkable in-
2
4
crease of the reaction rate was observed at low degrees of H0-
DBT conversion.
Figure 8 clearly illustrates increased reaction rates for both
experiments applying a mixed gas phase hydrogen substrate.
Compared to the runs with pure hydrogen, higher degrees of
hydrogenation were achieved after given reaction times. Fur-
ther experiments featuring different methane partial pressures
(see the Supporting Information) did not reveal any further in-
fluence on reaction rate or reaction time (until full hydrogena-
tion was reached). In addition, the influence of stirrer speed
was examined using the same hydrogen/methane mixture
(40 bar hydrogen/20 bar methane). Increase in stirrer speed
It is fair to note, though, that nearly all studies on CMD to
date have been performed at ambient pressure as an increase
in total pressure is expected to have a detrimental effect on
the reaction rate owing to thermodynamic effects.[38] Actually,
CMD conducted under pressure is a largely uninvestigated
field of research in the area of methane decomposition. There-
fore, it is expected that some compression of the methane/hy-
drogen mixture from CMD is required to provide the pressure
for the hydrogenation step. However, the energy input into
this compression step will depend on the compression ratio
and with that the starting pressure delivered by the CMD step
is important. This turns studies of CMD under even slight pres-
sures into a highly relevant field for further investigations.
Experimental Section
Catalytic methane decomposition
The 20 wt% Ni/Al2O3 catalyst used in this work was prepared by in-
cipient wetness impregnation of g-Al2O3 (Sasol Germany) with an
aqueous solution of Ni(NO3)2·6H2O (Sigma–Aldrich). Prior to im-
pregnation the g-Al2O3 spheres were ground and sieved to a parti-
cle size of 500–630 mm. The impregnated sample was dried at
1008C for 24 h and subsequently calcined at 5008C for 4 h. The
metal loading was verified by inductively coupled plasma atomic
emission spectroscopy (ICP-AES). Prior to reaction the catalyst was
reduced in a 50 mLminꢁ1 hydrogen (Air products) stream for 2 h.
Figure 8. Comparison of hydrogenation performance by using pure hydro-
gen and a hydrogen/methane mixture; T=1808C, 5.9 mol DBT, 0.25 mol%
Ru applied as 5 wt% Ru on Al2O3.
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Concepts
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The methane decomposition experiments were carried out at at-
mospheric pressure in a fixed-bed quartz reactor (internal diame-
ter: 11 mm, length: 700 mm) at temperatures ranging from 550 to
7008C. 0.44 g of catalyst, corresponding to a bed height of 5 mm
was used for each run. The feed consisted of pure methane
(grade 3.5 corresponding to a purity of >99.95%, Westfalen AG)
adjusted to a gas hourly space velocity (GHSV) of 12500 hꢁ1. The
composition of the outlet stream was analyzed by an on-line gas
chromatograph (Bruker 456-GC) equipped with two thermal con-
ductivity detectors. No methane decomposition products other
than hydrogen were detected in the effluent gas during the experi-
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LOHC hydrogenation
The hydrogenation experiments were performed by using a 5.3 L
stainless-steel batch autoclave applied with a gas inducing stirrer
(Bꢀchi Glas). All experiments were performed with a 5 wt% Ru/
Al2O3 hydrogenation catalyst supplied by Alfa Aesar. The molar cat-
alyst to LOHC ratio was constant at 1:400 (0.25 mol%). The pres-
sure vessel was filled with catalyst and approximately 5.9 mol fully
dehydrogenated DBT (Sasol Germany). Inert atmosphere was en-
sured by repeatedly purging the reactor with nitrogen (grade 5.0
corresponding to a purity of >99.999 %, Linde AG). The reactor
was heated to reaction temperature using a thermostat (Julabo
HT60m2) and then pressurized with hydrogen (grade 5.0 corre-
sponding to a purity of >99.999 %, Linde AG) in a range of 1 to
55 bar (0.1–5.5 MPa). In case of the hydrogenation experiments ap-
plying a hydrogen/methane mixture, the pressure vessel was pres-
surized with a defined amount of methane (grade 2.5 correspond-
ing to a purity of >99.5 %, Linde AG) resulting in a pressure in the
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Received: April 2, 2016
Revised: May 10, 2016
Published online on && &&, 0000
&
ChemSusChem 2016, 9, 1 – 7
www.chemsuschem.org
6
ꢁ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

CONCEPTS
S. Dꢀrr, M. Mꢀller, H. Jorschick,
M. Helmin, A. Bçsmann, R. Palkovits,*
P. Wasserscheid*
&& – &&
Carbon Dioxide-Free Hydrogen
Production with Integrated Hydrogen
Separation and Storage
LOHC it in: Combining catalytic meth-
ane decomposition with hydrogen pu-
rification and storage by hydrogenation
of LOHC systems offers a versatile and
economically attractive way for upgrad-
ing stranded gas towards green, CO2-
free hydrogen production.
ChemSusChem 2016, 9, 1 – 7
www.chemsuschem.org
7
ꢁ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
These are not the final page numbers! ÞÞ