Selective Production of Carbon Monoxide via Methane Oxychlorination over Vanadyl Pyrophosphate

Article abstract of DOI:10.1002/anie.201608165

A catalytic process is demonstrated for the selective conversion of methane into carbon monoxide via oxychlorination chemistry. The process involves addition of HCl to a CH₄–O₂feed to facilitate C?H bond activation under mild conditions, leading to the formation of chloromethanes, CH₃Cl and CH₂Cl₂. The latter are oxidized in situ over the same catalyst, yielding CO and recycling HCl. A material exhibiting chlorine evolution by HCl oxidation, high activity to oxidize chloromethanes into CO, and no ability to oxidize CO, is therefore essential to accomplish this target. Following these design criteria, vanadyl pyrophosphate (VPO) was identified as an outstanding catalyst, exhibiting a CO yield up to approximately 35 % at 96 % selectivity and stable behavior. These findings constitute a basis for the development of a process enabling the on-site valorization of stranded natural-gas reserves using CO as a highly versatile platform molecule.

Full text of DOI:10.1002/anie.201608165

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International Edition: DOI: 10.1002/anie.201608165
German Edition: DOI: 10.1002/ange.201608165
Methane Valorization
Hot Paper
Selective Production of Carbon Monoxide via Methane
Oxychlorination over Vanadyl Pyrophosphate
+
+
´
Vladimir Paunovic , Guido Zichittella , Rꢀne Verel, Amol P. Amrute, and Javier Pꢀrez-Ramꢁrez*
Abstract: A catalytic process is demonstrated for the selective
conversion of methane into carbon monoxide via oxychlori-
nation chemistry. The process involves addition of HCl to
direct methane functionalization under moderate operating
conditions (ca. 1 bar, < 853 K).[4–6] This route has traditionally
targeted the production of methyl halides (CH3Cl and
CH3Br), platform molecules equivalent to methanol that
can be transformed into a wide spectrum of value-added
chemicals and fuels via a halogen elimination step (hydrogen
halide is liberated). Recent reports demonstrate the high
selectivity to halomethanes over LaOCl and CeO2 in oxy-
chlorination, and over CeO2 and vanadyl pyrophosphate
(VPO) in oxybromination.[4–6] Moreover, the oxyhalogena-
tion of methane over catalysts with mild oxidizing properties,
such as LaOCl in oxychlorination and FePO4 and VPO in
oxybromination, led to CO as the dominant oxidation
product, with only marginal CO2 production.[4a,5–7] These
findings hint at the extra potential of the route as an effective
method to exploit the natural gas feedstock for on-purpose
production of CO, which is a key building block in the
manufacture of numerous commodities.[8] In this way, the
highly endergonic steam reforming and coal gasification
processes, commonly practiced today to obtain CO, could be
substituted by an exergonic halogen-mediated process. Never-
theless, this application of the oxyhalogenation reaction has
not been considered to date; this is probably due to the fact
that CO was never produced at a selectivity exceeding
50%,[4,6,7] which would necessitate a complex downstream
separation train. Alternatively, a two-step process can be
sought, involving selective methane oxyhalogenation over
one catalyst, followed by oxidation/hydrolysis into CO over
a second catalyst.[9] Although the latter step was typically
studied with an aim to convert halomethanes into CO2,
catalysts such as alumina and La-based materials could yield
CO with a relatively high selectivity, which however depends
on the nature of the halomethane.[9c] Nonetheless, integration
of halomethane formation with their subsequent oxidation/
dehydrohalogenation into CO over a single catalyst is highly
desirable in view of process intensification. However,
a tandem process of this type is rather challenging from the
point of view of catalyst design as it requires a fine balance
between the catalyst activities in two reactions. In such
a hypothetical process, the use of HCl as a halogenating agent
would be desirable instead of HBr because of the lower
corrosiveness and the much higher availability of the
former.[10]
À
a CH4–O2 feed to facilitate C H bond activation under mild
conditions, leading to the formation of chloromethanes, CH3Cl
and CH2Cl2. The latter are oxidized in situ over the same
catalyst, yielding CO and recycling HCl. A material exhibiting
chlorine evolution by HCl oxidation, high activity to oxidize
chloromethanes into CO, and no ability to oxidize CO, is
therefore essential to accomplish this target. Following these
design criteria, vanadyl pyrophosphate (VPO) was identified
as an outstanding catalyst, exhibiting a CO yield up to
approximately 35% at 96% selectivity and stable behavior.
These findings constitute a basis for the development of
a process enabling the on-site valorization of stranded natural-
gas reserves using CO as a highly versatile platform molecule.
M
ethane, the principal constituent of natural gas, is an
important energy resource and an attractive feedstock for the
manufacture of chemicals and fuels.[1] However, > 30% of
abundant natural-gas reserves are allocated in small reser-
voirs and/or remote areas, wherein the high transportation
costs of methane and marked capital expenditure of the
existing syngas-based gas-to-liquid (GTL) technologies
hamper their efficient exploitation.[1a,b,2] Consequently, copi-
ous amounts of natural gas retrieved from these stranded
wells are nowadays burned to reduce anthropogenic green-
house gas emissions—the global warming potential of CH4 is
ꢀ 21 times higher than that of CO2. Disparagingly, the so-
called “flaring” wastes around 3.5% of the global natural gas
production—a quantity worth approximately 13 billion USD
and comparable to the current fraction of the worldꢀs natural
gas supply used for the manufacture of commodities
(< 10%).[1d,3] This alarming situation calls for the develop-
ment of modular, decentralized processes for the economical
harvesting of stranded gas.[1b,2a]
The catalytic oxyhalogenation of methane, comprising its
reaction with a hydrogen halide (HCl or HBr) and oxygen, is
an attractive approach to satisfy these objectives as it enables
[+]
[*] V. Paunovic, G. Zichittella,[+] Dr. R. Verel, Dr. A. P. Amrute,
´
Prof. J. Pꢀrez-Ramꢁrez
Institute for Chemical and Bioengineering
Department of Chemistry and Applied Biosciences, ETH Zurich
Vladimir-Prelog-Weg 1, 8093 Zurich (Switzerland)
E-mail: jpr@chem.ethz.ch
Herein, we present the one-step selective conversion of
CH4 into CO via oxychlorination chemistry (Figure 1). This
alternative methane valorization route 1) generates the
versatile feedstock CO,[8] 2) allows for in situ HCl recycling,
and 3) enables heat integration in other processing steps.
Consequently, it is essential to find a catalyst showing high
activity for oxychlorination of methane to chloromethanes
[+] These authors contributed equally to this work.
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/anie.201608165.
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Figure 1. CO is the chief carbonylating agent for production of a wide
variety of commodities such as acids, alcohols, and isocyanates.
Integration of methane oxychlorination with the selective oxidation of
the thus obtained chloromethanes into CO, over a single catalytic
material, is an attractive route to valorize stranded natural gas.
and strong propensity for the selective oxidation of the latter
into CO under oxychlorination conditions (Figure 1).
To approach the above targeted catalytic process, a series
of bulk materials with different oxidation properties,[6,11]
comprising RuO2, CeO2, LaVO4, Nb2O5, TiO2, and VPO,
were prepared and characterized by X-ray diffraction and N2
sorption, respectively (Supporting Information, Figure S1,
Table S2). Their performance in the oxychlorination of
methane is compared by taking the temperature at which
approximately 15% CH4 conversion is achieved, T15, as
a relative measure of their overall catalytic activity (Figure 2,
top), while product distribution at this relatively low con-
version level was used to fingerprint their inherent reaction
kinetics (Figure 2, bottom). The results are presented on the
basis of an increasing selectivity to CO, which is considered
here as the principal descriptor of the catalyst performance.
Based on their activity patterns, the catalysts can be classified
into four different categories. The first class is represented by
RuO2, a well-established HCl oxidation catalyst,[10a] exhibit-
ing the highest activity for methane conversion as inferred
from its lowest value of T15. Nevertheless, the oxychlorination
reaction over this material leads to a pronounced CO2
formation, as can be expected from its strong propensity to
oxidize CH4, chloromethanes, and possible CO intermediate,
into CO2.[6,12] On the other hand, CeO2 predominantly
produces chloromethanes, in line with previous studies
reporting its outstanding selectivity to these products in the
oxyhalogenation reaction.[5,6] The third class of catalysts
comprises mild oxidizers such as LaVO4 and Nb2O5,[11]
exhibiting low activity for CH4 conversion (the highest
values of T15; Figure 2). Although CO is the dominant
oxidation product, a significant part of the chloromethanes
remains unconverted even at high reaction temperatures, thus
hampering the closure of the HCl loop. Finally, TiO2 and VPO
show inherently high selectivity to CO and moderate activity
in converting CH4. The unprecedentedly suppressed CO2
formation over VPO (ꢁ 1% in selectivity) coupled to the
low residual amounts of chloromethanes, make it a highly
attractive catalyst for selective CO production from methane
via oxychlorination chemistry. This unique performance of
VPO and TiO2 is understood with a series of catalytic tests
(Supporting Information, Figure S2; Figure 3). In contrast to
Figure 2. Selectivity to product j, S(j), in the oxychlorination of
methane over various catalysts at ca. 15% of CH4 conversion, which is
obtained at temperature T15 indicated in the top plot. A full set of
experiments is presented in Figure S2 (Supporting Information).
Conditions: FT/Wcat =100 cm3 minÀ1 gÀ1, feed molar composition
CH4:HCl:O2:Ar:He=6:6:3:4.5:80.5, and P=1 bar.
CeO2 and RuO2, where evolution of CO2 is enhanced at high
reaction temperatures (Supporting Information, Figure S2),
in the oxychlorination of methane over TiO2 and particularly
VPO, the production of CO2 remains low in a very broad
temperature range (Figures 3a,b). In the case of VPO, 33%
yield and 96% selectivity for CO are achieved at 836 K. Only
trace amounts of H2 are detected, while HCl conversion is
ꢁ 1.5% (Supporting Information, Table S3), which suggests
that the biggest part of HCl is recycled in situ in a single
reactor pass. The selectivity to CO and CO2 generally
increases and that to halomethanes decreases (Supporting
Information, Figure S2; Figures 3a,b) upon raising the reac-
tion temperature, suggesting the consecutive oxidation of the
chloromethanes generated in the first oxychlorination step as
the plausible pathway of CO formation. Nevertheless, the
latter products might in principle evolve from the direct
oxidation of methane over a catalyst. To elucidate the
contribution of these two routes to the CO formation over
VPO and TiO2, the direct oxidation of methane (Figure 3a,
open symbols) as well as the impact of feed HCl concen-
tration on reaction performance (Supporting Information,
Figure S3) were also studied. The negligible CH4 conversion
over both VPO and TiO2 in the direct oxidation, at temper-
atures which are significantly higher compared to those
applied in the oxychlorination reaction, and an increase in
CH4 conversion upon increasing the inlet HCl concentration,
demonstrates the pivotal role of HCl in activating methane
and corroborates the oxidation of halomethanes as the
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Figure 3. Conversion of reactant i, X(i), and selectivity to product j, S(j), over VPO (blue) and TiO2 (red) versus temperature in: a, b) methane
oxychlorination (CH4:HCl:O2:Ar:He=6:6:3:4.5:80.5) and oxidation (CH4:O2:Ar:He=6:3:4.5:86.5); c, d) CH3Cl oxidation (CH3Cl:O2:Ar:He=
1:3:4.5:91.5); e, f) CH2Cl2 oxidation (CH2Cl2:O2:HCl:Ar:He=1:3:0(6):4.5:91.5(85.5)); g) HCl oxidation (HCl:O2:He=6:3:91); and h) CO oxidation
(CO:O2:HCl:Ar:He=1:3:0(6):4.5:91.5(86.5)). Open symbols denote the points taken in the absence of HCl in the feed. Conditions: FT/Wcat
=
100 cm3 minÀ1 gÀ1 and P=1 bar.
principal source of CO over these two catalysts. To support
the above-indicated consecutive pathway, the activities of
VPO and TiO2 in the oxidation of chloromethanes were
further assessed, as presented in Figures 3c–f. In good
agreement with the oxychlorination tests, CO is produced
with very high selectivity (> 99%) in both CH3Cl and CH2Cl2
oxidation over VPO (Figures 3d,f), while in the case of TiO2,
the selectivity to CO observed in the oxidation of CH3Cl (ca.
90%) is lower than that obtained in the oxidation of CH2Cl2
(> 99%). Besides, the light-off curves for the conversion of
chloromethanes over TiO2 are shifted to lower temperatures
than that over VPO, indicating its higher activity in these
reactions, which at first glance contrasts the results presented
in Figures 2 and 3b. This might be explained by the
substantially higher activity of VPO in the HCl oxidation
reaction (Figure 3h), indicating the higher propensity of this
catalyst to evolve chlorine, and thus the enhanced production
of the precursor chloromethanes, leading to a higher CO
productivity. Inhibition of chloromethanes oxidation by HCl
poisoning of TiO2 (which has been reported often in the
catalytic abatement of chlorocarbons over oxide materials)
might also contribute to the difference in performance among
the two catalysts.[9c,13] To check for the latter effect, HCl was
co-fed with CH2Cl2 and O2 in the corresponding oxidation test
to simulate the conditions of the oxychlorination reaction
(Figures 3e,f). The results demonstrate a significant drop in
CH2Cl2 conversion over TiO2 in the presence of HCl, thus
corroborating the inhibitory role of HCl, contributing to the
inferior activity of this material compared to VPO in the
oxychlorination of methane.
The differences in performance of VPO and TiO2 in the
oxychlorination reaction, as well as those in the oxidation of
halomethanes, are further explained by evaluating their
activities in CO oxidation (Figure 3h, open symbols). VPO
shows much lower conversion of CO into CO2 than TiO2
(Figure 3h), which is likely caused by its inherently low
propensity to adsorb CO.[14] Nevertheless, in analogy to the
CH2Cl2 oxidation, CO conversion over TiO2 is substantially
suppressed in the presence of HCl (Figure 3h, closed
symbols), which might explain the low CO2 productivity
observed in the oxychlorination of methane.
Based on these results, CO production from CH4 over
VPO can be rationalized by a mechanism comprising HCl
oxidation into Cl2, followed by gas-phase methane chlorina-
tion, which is analogous to that proposed for methane
oxybromination over this material.[6] This is supported by
the ability of VPO to oxidize HCl into Cl2 (Figure 3g), and its
low activity in the direct oxidation of methane (Figure 3a),
À
indicating its minor propensity to cleave C H bonds. More-
over, the temperature window of the HCl oxidation coincides
with that of methane oxychlorination, suggesting that the
evolved Cl2 readily reacts with methane. This is in line with
literature reports testifying the vigorous kinetics of methane
chlorination already at 673 K,[1c] and it is also corroborated by
the low Cl2 concentration detected at the reactor outlet
(Supporting Information, Table S3). The ability of VPO to
oxidize HCl at temperatures that are comparable or even
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higher than those needed for chloromethanes oxidation is
uniquely combined with its inherent propensity to suppress
the oxidation of CO into CO2, eventually resulting in a highly
selective production of CO from methane via the oxychlori-
nation reaction. Notably, the oxybromination reaction over
VPO yields CO as the principal oxidation product. Still, the
generation of CO is generally overwhelmed by the formation
of bromomethanes, even at high reaction temperatures,[6]
which might be explained by significantly faster HBr oxida-
tion compared to bromomethanes oxidation (Supporting
Information, Figure S4). The exceptional CO production via
methane oxychlorination over VPO is shown to be stable by
a 100 h on-stream test (Figure 4a). X-ray diffraction (XRD)
it could provide an effective means of bringing carbon,
hydrogen, and/or energy equivalents of stranded methane
reserves to the market in a liquid form. Alternatively, the on-
site water-gas shift reaction of the CO–H2O mixture could
generate hydrogen.[17] In this way, traditional syngas-to-
chemicals transformations, such as methanol production or
Fischer–Tropsch (F-T) hydrocarbon synthesis, can be prac-
ticed by circumventing steam-reforming (1073–1273 K,
20–30 bar) or auto-reforming (> 2273 K, < 100 bar) process-
es, which are the most energy- and capital-demanding steps of
the commercial syngas generation technologies.[1,18] More-
over, H2 derived from renewable sources, such as photo-
catalytic water splitting or biomass reforming,[19] might also be
utilized.
In conclusion, we have demonstrated the first example of
highly selective one-step CO production from methane via
oxychlorination chemistry. Following simple catalyst design
criteria—requiring that the optimal catalyst for this process
should exhibit the chlorine evolution activity essential to
support the formation of chloromethanes and the ability to
selectively oxidize the latter into CO—various materials
families possessing different redox properties were evaluated
in the oxychlorination of methane. VPO, which exhibited
a high selectivity to halomethanes in methane oxybromina-
tion, emerged as an outstanding catalyst for CO production
via methane oxychlorination, demonstrating the complexity
and versatility of oxyhalogenation chemistry. A yield of CO
up to approximately 35% at 96% selectivity was achieved
over this catalyst under ambient pressure and temperatures
< 835 K. The exceptional performance of VPO, which was
stable over 100 h on stream, constitutes the basis for develop-
ment of a modular, decentralized process for the valorization
of stranded natural gas by exploiting CO as a well-established
platform molecule for the manufacture of value-added
commodities.
Figure 4. a) Methane conversion and product selectivity versus time-
on-stream (tos) in the oxychlorination of methane over VPO. b) 31
P
nuclear magnetic resonance spectra by spin-echo mapping of fresh
and used VPO recovered after x h on stream. Conditions: FT/Wcat
=100 cm3 minÀ1 gÀ1, CH4:HCl:O2:Ar:He=6:6:3:4.5:80.5, T=803 K,
and P=1 bar.
analysis of the fresh and used samples recovered after
different time-on-stream durations (Supporting Information,
Figure S5) indicated the equilibration of the starting
(VO)2P2O7 structure within the first 1 h of operation, which
remains unaltered over the whole evaluated period of time.
31P nuclear magnetic resonance by spin-echo mapping
(Figure 4b) showed a major peak centered at around
2500 ppm, which is characteristic for a (VO)2P2O7 phase.[15]
This peak is slightly broader in the case of the fresh catalyst
sample, but shows no significant changes among the used
catalyst, in line with XRD data. No peaks ascribed to V3+
phases (located at ca. 4700 ppm) could be observed, while
a small peak located around 0 ppm, which is more pro-
nounced in the case of used catalyst samples, indicates the
presence of V5+ sites. This is further corroborated by temper-
ature-programmed reduction with H2 (Supporting Informa-
tion, Figure S5) and X-ray photoelectron spectroscopy (Sup-
porting Information, Table S4, Figure S6), which also point to
the presence of V5+ sites in the surface region of all catalyst
samples.
Experimental Section
Commercial CeO2 was treated at 1173 K, while rutile TiO2 and Nb2O5
were treated in static air at 873 K, respectively, prior to their use in the
catalytic tests. RuO2 was prepared by thermal decomposition of
RuCl3 at 823 K in static air. LaVO4 was synthetized by co-
precipitation of La(NO3)3·6H2O with NH4VO4, followed by hydro-
thermal synthesis at 453 K for 24 h. After filtration and washing with
water and methanol, the powder was dried in vacuum at 373 K and
calcined at 873 K. VPO was prepared by refluxing a slurry containing
V2O5, benzyl alcohol, and isobutyl alcohol for 3 h. Subsequently,
H3PO4 was added (P:V= 1.2) and the slurry was refluxed for 16 h,
followed by drying in vacuum at 373 K and thermal treatment at
873 K under flowing nitrogen. A heating rate of 5 KminÀ1 and holding
time of 5 h were applied in all thermal treatments of the catalysts. The
catalytic tests were performed at 1 bar in a continuous-flow fixed-bed
reactor set-up (Supporting Information, Scheme S1) using a catalyst
weight
Wcat = 1.0 g (particle size = 0.4–0.6 mm) well-mixed with
quartz (particle size = 0.2–0.3 mm) and
a
total gas flow FT =
100 cm3 STPminÀ1 at bed temperatures, T, in the range of 423–
875 K. The molar composition of the mixtures in methane oxy-
chlorination (CH4:HCl:O2:Ar:He = 6:6:3:4.5:80.5), methane oxida-
tion (CH4:O2:Ar:He = 6:3:4.5:86.5), and the oxidation of CH3Cl/
CH3Br (CH3Cl/CH3Br:O2:Ar:He = 1:3:4.5:91.5), CH2Cl2/CH2Br2
(CH2Cl2/CH2Br2:O2:HCl:Ar:He = 1:3:0(6):4.5:91.5(85.5)), HCl/HBr
(HCl:O2:Ar:He = 6:3:4.5:86.5), and CO (CO:O2:HCl:Ar:He =
The unique performance of VPO opens a way for the
development of a novel process for natural gas upgrading by
exploiting CO as a versatile platform molecule. In particular,
if coupled with the well-established production of formic acid,
a valued chemical and highly prospective energy carrier,[16]
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1:3:0(6):4.5:91.5(85.5)) were set using digital mass flow controllers to
feed the gases, while CH2Cl2 or CH2Br2 were fed by syringe pump and
homemade evaporation unit. Concentrations of the carbon-
2488 – 2492; b) Z. Guo, B. Liu, Q. Zhang, W. Deng, Y. Wang, Y.
Yang, Chem. Soc. Rev. 2014, 43, 3480 – 3524.
´
a
[6] V. Paunovic, G. Zichittella, M. Moser, A. P. Amrute, J. Pꢁrez-
containing compounds at the reactor inlet and outlet were analyzed
online using a gas chromatograph coupled to a mass spectrometer.
The concentration of H2 was determined by an off-line gas chromato-
graph equipped with a thermal conductivity detector. The Cl2
concentration was quantified using an off-line iodometric titration
of the absorbing KI solution, while the HCl concentration was
determined by acid–base titration after its absorption into H2SO4
solution. The errors of carbon and chlorine balances were lower than
5%. The fresh and used catalysts were characterized by means of
X-ray diffraction, N2 sorption, X-ray fluorescence, temperature-
programmed reduction with H2, 31P nuclear magnetic resonance spin-
echo mapping, and X-ray photoelectron spectroscopy. More details
on catalyst preparation, characterization, and testing are provided in
the Supporting Information.
Ramꢂrez, Nat. Chem. 2016, 8, 803 – 809.
[7] R. Lin, Y. Ding, L. Gong, W. Dong, J. Wang, T. Zhang, J. Catal.
2010, 272, 65 – 73.
[8] J. Bierhals, Ullmannꢂs Encyclopedia of Industrial Chemistry,
Vol. 6, Wiley-VCH, Weinheim, 2012, pp. 679 – 693.
[9] a) R. W. van den Brink, P. Mulder, R. Louw, G. Sinquin, C. Petit,
J.-P. Hindermann, J. Catal. 1998, 180, 153 – 160; b) P. Van der
Avert, B. M. Weckhuysen, Angew. Chem. Int. Ed. 2002, 41,
4730 – 4732; Angew. Chem. 2002, 114, 4924 – 4926; c) P. Van der
Avert, B. M. Weckhuysen, Phys. Chem. Chem. Phys. 2004, 6,
5256 – 5262; d) A. W. A. M. van der Heijden, M. Garcia Ramos,
B. M. Weckhuysen, Chem. Eur. J. 2007, 13, 9561 – 9571;
e) A. W. M. van der Heijden, S. G. Podkolzin, M. E. Jones, J. H.
Bitter, B. M. Weckhuysen, Angew. Chem. Int. Ed. 2008, 47,
5002 – 5004; Angew. Chem. 2008, 120, 5080 – 5082;
f) A. W. A. M. van der Heijden, A. J. M. Mens, R. Bogerd,
B. M. Weckhuysen, Catal. Lett. 2008, 122, 238 – 246.
[10] a) J. Pꢁrez-Ramꢂrez, C. Mondelli, T. Schmidt, O. F.-K. Schlꢃter,
A. Wolf, L. Mleczko, T. Dreier, Energy Environ. Sci. 2011, 4,
4786 – 4799; b) P. Schmittinger, T. Florkiewicz, L. C. Curlin, B.
Lꢃke, R Scannel, T. Navin, E. Zelfel, R. Bartsch, Ullmannꢂs
Encyclopedia of Industrial Chemistry, Vol. 8, Wiley-VCH, Wein-
heim, 2012, pp. 531 – 621; c) S. Boldyryev, P. S. Varbanov, Chem.
Eng. Trans. 2014, 39, 1423 – 1428.
Acknowledgements
Funding by the Swiss National Science Foundation (project
no. 200021-156107) and ETH Zurich (research grant ETH-04
16-1) is acknowledged. Nicolas Aellen is thanked for per-
forming part of the catalytic tests. Dr. Roland Hauert is
acknowledged for conducting X-ray photoemission spectros-
copy measurements.
[11] a) C. T. Au, W. D. Zhang, H. L. Wan, Catal. Lett. 1996, 37, 241 –
246; b) M. Ziolek, Catal. Today 2003, 78, 47 – 64.
[12] H. Madhavaram, H. Idriss, S. Wendt, Y. D. Kim, M. Knapp, H.
Over, J. Aßmann, E. Lçffler, M. Muhler, J. Catal. 2001, 202, 296 –
307.
[13] Q. Dai, X. Wang, G. Lu, Appl. Catal. B 1999, 81, 192 – 202.
[14] G. Busca, G. Centi, F. Trifirꢄ, V. Lorenzelli, J. Phys. Chem. 1986,
90, 1337 – 1344.
Keywords: C1 chemistry · carbon monoxide ·
heterogeneous catalysis · methane oxychlorination ·
natural-gas upgrading
[15] M. T. Sananes, A. Tuel, Solid State Nucl. Magn. Reson. 1996, 6,
157 – 166.
[16] a) J. Hietala, A. Vuori, P. Johnsson, I. Pollari, W. Reutemann, H.
Kieczka, Ullmannꢂs Encyclopedia of Industrial Chemistry,
Wiley-VCH, Weinheim, 2016, pp. 1 – 22, DOI: 10.1002/
14356007.a12_013.pub3; b) J. J. A. Celaje, Z. Lu, E. A. Kedzie,
N. J. Terrile, J. N. Lo, T. J. Williams, Nat. Commun. 2016, 7,
11308 – 11313; c) D. Mellmann, P. Sponholz, H. Junge, M. Beller,
Chem. Soc. Rev. 2016, 45, 3954 – 3988.
[1] a) J. H. Lunsford, Catal. Today 2000, 63, 165 – 174; b) E. McFar-
land, Science 2012, 338, 340 – 342; c) G. A. Olah, A. Goeppert,
G. K. Surya Prakash, Beyond Oil and Gas: The Methanol
Economy, Wiley-VCH, Weinheim, 2009, pp. 29 – 53 and
pp. 249 – 251; d) R. Horn, R. Schlçgl, Catal. Lett. 2015, 145,
23 – 39.
[2] a) J. A. Labinger, J. E. Bercaw, Nature 2002, 417, 507 – 514; b) R.
Khalilpour, I. A. Karimi, Energy 2012, 40, 317 – 328; c) Petro-
Wiki press release, 2016. Stranded gas, www.petrowiki.com,
accessed June 5th, 2016, 10:00 GMT.
[17] C. Ratnasamy, J. P. Wagner, Catal. Rev. Sci. Eng. 2009, 51, 325 –
440.
[18] J. Richard, R. Nielsen in Handbook of Heterogeneous Catalysis
(Eds.: G. Ertl, H. Knçzinger, F. Schꢃth, J. Weitkamp), Wiley-
VCH, Weinheim, 2008, chap. 13.11, pp. 2882 – 2905.
[19] J. D. Holladay, J. Hu, D. L. King, Y. Wang, Catal. Today 2009,
139, 244 – 260.
[3] a) J. Tollefson, Nature 2016, DOI: 10.1038/nature.2016.19141;
b) U.S. Energy Information Administration, Monthly Energy
Review June 2016, U.S. Department of Energy, Washington, U.S.,
2016.
[4] a) E. Peringer, S. G. Podkolzin, M. E. Jones, R. Olindo, J. A.
Lercher, Top. Catal. 2006, 38, 211 – 220; b) S. G. Podkolzin, E. E.
Stangland, M. E. Jones, E. Peringer, J. A. Lercher, J. Am. Chem.
Soc. 2007, 129, 2569 – 2576.
Received: August 21, 2016
[5] a) J. He, T. Xu, Z. Wang, Q. Zhang, W. Deng, Y. Wang, Angew.
Chem. Int. Ed. 2012, 51, 2438 – 2442; Angew. Chem. 2012, 124,
Revised: October 10, 2016
Published online: && &&, &&&&
Angew. Chem. Int. Ed. 2016, 55, 1 – 6
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

Angewandte
Communications
Chemie
Communications
Methane Valorization
Natural value: Highly selective carbon
monoxide production from methane over
vanadyl pyrophosphate, via oxychlorina-
tion chemistry, offers a credible route by
which stranded natural gas may be
exploited. On-site manufacture of value-
added chemicals and fuels from a carbon
monoxide feedstock is readily fore-
seeable.
´
V. Paunovic, G. Zichittella, R. Verel,
A. P. Amrute,
J. Pꢁrez-Ramꢂrez*
&&&& — &&&&
Selective Production of Carbon Monoxide
via Methane Oxychlorination over
Vanadyl Pyrophosphate
6
www.angewandte.org
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2016, 55, 1 – 6
These are not the final page numbers!