Increasing the activity of copper exchanged mordenite in the direct isothermal conversion of methane to methanol by Pt and Pd doping

Article abstract of DOI:10.1039/C8SC02795A

PtCu- and PdCu-mordenite allow for isothermal reaction at 200 °C for the stepwise methane to methanol conversion with comparably high yields. In contrast to traditional Cu-zeolites, these materials are more reactive under isothermal conditions than after high temperature activation.

Full text of DOI:10.1039/C8SC02795A

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Increasing the activity of copper exchanged
mordenite in the direct isothermal conversion of
Cite this: Chem. Sci., 2019, 10, 167
methane to methanol by Pt and Pd doping†
All publication charges for this article
have been paid for by the Royal Society
of Chemistry
ab
ab
a
ac
P. Tomkins,
A. Mansouri,
V. L. Sushkevich,
M. Ranocchiari
L. I. van der Wal,
ab
b
a
and J. A. van Bokhoven *ab
S. E. Bozbag,
F. Krumeich,
Received 25th June 2018
Accepted 28th September 2018
ꢀ
PtCu- and PdCu–mordenite allow for isothermal reaction at 200 C for the stepwise methane to methanol
conversion with comparably high yields. In contrast to traditional Cu-zeolites, these materials are more
reactive under isothermal conditions than after high temperature activation.
DOI: 10.1039/c8sc02795a
rsc.li/chemical-science
30
Methane is an abundant feedstock that can be extracted inex- active site or as precursor to the active site. Generally, oxygen
1
pensively from shale gas and other sources. Costs of trans- is used during activation and the active sites start being formed
ꢀ
portation are comparably high and a major part of the methane, at about 280 C in Cu-ZSM-5 (ref. 15) and, generally, activation
1
ꢀ
31
recovered as a side-product in oil elds, is ared. There are above 450 C is benecial. We most recently investigated the
strategies for converting methane to higher value-added reaction, in which water can be used as oxidant aer activation
2,3
32,33
chemicals, but the conversion of methane to liquids is at high temperature.
a complex process. Industrial methanol synthesis is energy 160 mmol g for Cu-MOR and 125 mmol g for Cu-CHA.
intense, as it requires the production of synthesis gas. Methane Most reports focus on a single stoichiometric conversion, but
products of partial oxidation are more reactive than methane reusability has already been proven.
itself, which fundamentally limits the yield of methanol from nitrogen monoxide as the oxidant resulted in very low methanol
the direct methane oxidation. Successes have been achieved yields of up to 0.629 mmol g , assumed to be achieved over the
on systems that produce derivatives of initial oxidation prod- mono-m-oxo site. We recently discovered the isothermal
ucts, however, these turned out not to currently be industrially stepwise conversion of methane to methanol at 200 C using
Maximum yields achieved so far were
ꢁ1
ꢁ1
23,34
18,35
Isothermal cycles with
3
4–6
ꢁ1
21
ꢀ
7,8
ꢁ1 36
feasible.
Cu-MOR with yields up to 56.2 mmol g
.
In this case the
Methane monooxygenase enzymes transform methane to activation in oxygen, reaction with methane and extraction with
9
10
methanol at low temperature with active dicopper or diiron
water can be performed successively at the same temperature
sites. The same motif has also been transferred to solid catalysts (Fig. S1†). Several cycles of the reaction could be carried out with
1
1–13
14–23
24,25
based on Fe-,
Cu-
and Co-exchanged
zeolites, silica constant methanol yield. Higher methane pressures were
ꢀ
and alumina. High temperature ($450 C) activates these employed to allow for the reaction to happen over the less
materials by means of molecular oxygen. The activated mate- reactive clusters, of which the stability generally increases with
rial then reacts with methane at a signicantly lower tempera- cluster size. Further, Cu-oxo clusters of different structure
ture (50 C to 200 C), forming strongly adsorbed methanol possess different activity under aerobic and anaerobic condi-
precursors. The adsorbed species can be extracted off-line with tions. This approach showed that it is fundamentally possible
a liquid or on-line in a wet gas stream (Fig. S1†).
for the structure of the active sites are bis-m-oxo,
dicopper sites and most recently tris-oxo sites.
22
37
ꢀ
ꢀ
38
1
8,22
Proposals to allow for isothermal reaction by changing the reaction
1
4,17
mono-m-oxo parameters; we set out to search for novel materials that allow
16
15,18,23,26,27
for higher activity at low temperature.
To date, most studies use monometallic copper-zeolites
based on different topologies and material compositions for
28
Brønsted acid sites showed to be benecial for the reaction
I
II
and the reactivity matches well with that expected for a Cu /Cu
2
9
redox couple. Copper-loaded small-pore zeolites are also the transformation and these have so far not showed increased
22
active. For Cu-CHA a mono-Cu site was proposed as possible activity under isothermal conditions. Based on the well-known
39
interplay between copper and platinum group metals, we
envisioned mixed bimetallic Cu-oxo particles as being suitable
for the low temperature oxidation of methane to methanol.
Platinum group metals are oen excellent C–H activation
a
b
Paul Scherrer Institut, CH-5232 Villigen, Switzerland
ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland. E-mail: jeroen.
vanbokhoven@chem.ethz.ch
7,40
c
catalysts under mild conditions,
which might aid the reac-
Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
†
Electronic supplementary information (ESI) available. See DOI: tivity at low temperature. In addition, oxygen activation in
0.1039/c8sc02795a
1
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ꢀ
ꢁ1
ꢀ
ꢀ
mixed Cu–Pd and Cu–Pt complexes was recently described by gradually aer activation at 350 C (8.7 mmol g ) and at 450 C
ꢁ
1
Cramer and Tolman, which was proposed for direct methane to (30.1 mmol g ). The low activity of copper-zeolites at 200 C
methanol conversion. This might not only result in a changed activation and reaction is in agreement with the inactivity of
41
21
(
re-)oxidation process of the material, but also lead to different Cu-ZSM-5 under similar conditions. Pt-MOR (1 wt% Pt) and
6
ꢁ1
ꢁ1
6
reactivity towards methane. We herein investigate the stepwise Pd-MOR (2 wt% Pd) yielded 4.5 mmol g and 2.0 mmol g
conversion of methane to methanol using PtCu-MOR and PdCu- (Fig. 2), respectively. Both metals are known as C–H activation
7
MOR materials. In contrast to all copper zeolites, a decreasing catalysts, where they are used as homogeneous Catalytica and
4
2
activity with increasing activation temperature was observed Shilov systems.
and yields under isothermal conditions at 200 C were signi-
cantly higher than for Cu-MOR itself.
ꢀ
In analogy to the parent Cu-MOR8.5, the PtCu-MOR8.5
materials were employed in the cyclic methane to methanol
Cu-MOR8.5 with 4.3 wt% Cu was prepared by three-fold ion conversion aer activation at 200 C, 350 C and 450 C (Fig. 1).
ꢀ
ꢀ
ꢀ
exchange of Na-MOR (Si/Al ¼ 8.5) using Cu(OAc) . A series of Within this series there were two trends observable. On the one
2
PtCu-MOR8.5(Pt/Cutheory) materials was prepared by suspending hand using low temperature activation the yield increased with
ꢁ
1
Cu-MOR8.5 in
a
solution containing the Pt(NH
3
)
4
(NO
3
)
2
increasing Pt/Cu-ratio from 0.8 mmol g for Cu-MOR8.5 up to
ꢁ
1
precursor, subsequently water was evaporated to yield the nal (7.4 mmol g ) using PtCu-MOR8.5(0.35) under isothermal
material. Measured Pt and Cu contents can be found in Table conditions at 200 C. On the other hand, the yield decreased
S1.† Pt-content was lower than the employed amount of plat- with increasing platinum content aer 450 C activation from
ꢀ
ꢀ
ꢁ
1
ꢁ1
inum. PtCu-MOR8.5(0.35) was prepared from a parent Cu- 30.1 mmol g
for Cu-MOR8.5 to 2.7 mmol g
for PtCu-
MOR8.5 with 2.4 wt% Cu. The Pt/Cu- and Pd/Cu-ratios were MOR8.5(0.35). At an intermediary activation temperature of
ꢀ
more thoroughly evaluated using samples with Si/Al ¼ 6. 350 C the platinum-rich zeolites were less active, but the effect
ꢀ
Materials were prepared by impregnation of an analogously is not as pronounced as observed at 450 C activation. Thus,
6 2 6 2
prepared Cu-MOR . H PtCl dissolved in water or PdCl dis- PtCu-MOR with increasing Pt/Cu-ratio provides higher activity
solved in an aqueous HCl solution (30 wt%) were used, allowing under isothermal conditions, while the opposite is true aer
ꢀ
for rather predictable loading of the platinum over a broad 450 C activation. These results show the positive effect of
concentration range.
First, the effect of activation temperature on the methanol
18
yield was investigated (Fig. 1). The material was activated in
a ow of oxygen at the designated temperature, aer which the
ꢀ
reactor was maintained at to 200 C. Aer purging the reactor
with helium, methane was introduced at ambient pressure for
30 min and the reactor cooled down naturally in a ow of
helium, aer which the methanol was extracted off-line with
ꢀ
liquid water. Aer activation at 200 C, Cu-MOR8.5 yielded
ꢁ
1
0
.8 mmol g . Note that aer an isothermal reaction, Cu-MOR
ꢀ
only releases MeOH during extraction with steam at 200
C
(Fig. S3†), but there are strongly adsorbed carbon-containing
species remaining aer extraction that are transformed to CO
2
ꢀ
aer heating in O
2
at 300–350 C (Fig. S4†). The nal selectivity
is approximately 93% in this case, which was determined by
mass spectrometry of the extraction and subsequent oxidation
of the strongly adsorbed species to CO . The yield increased
2
Fig. 2 Methanol yield after activation in oxygen and reaction in
ꢀ
methane at 200 C with subsequent extraction in liquid water for
PtCu-MOR
Pt/Cu- and Pd/Cu-ratios prepared by incipient wetness impregnation
using H PtCl and PdCl at ambient pressure (top) and elevated
Fig. 1 Methanol yields of different PtCu-MOR8.5(Pt/Cutheory) materials pressures (bottom). These yields are compared to the parent Pt-MOR
prepared from Cu-MOR (Si/Al ¼ 8.5, 4.3 wt% Cu; #2.4 wt% for PtCu- and Pd-MOR. The yield for Cu-MOR at 6 bar CH was taken from
MOR8.5(0.35)) after activation at different temperatures. literature.
6
and PdCu-MOR
6
(Si/Al ¼ 6) materials with different
2
6
2
6
4
36
168 | Chem. Sci., 2019, 10, 167–171
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platinum for the isothermal conversion. The benecial effect of of 0.5 and a Pd/Cu ratio of 0.7 (Table S3†). The ratio of PdCu-
added platinum becomes even more obvious, when the yield is MOR (0.30) is somewhat higher than that of PtCu-MOR (0.15),
6
6
normalized to the amount of copper present in the material which can be caused by the higher metal loading. Note that
ꢀ
ꢁ1
(
Fig. S2†). Note that for materials that are doped with less Pt activation at 450 C resulted in a lower yield of 20 mmol g for
ꢁ
1
6
there is still an increase in yield with increasing activation PdCu-MOR (1.0) compared to 27 mmol g for the parent Cu-
6
temperature. This is caused by (rather large) fractions of the MOR under identical conditions (Table S4†). Thus, the intro-
material being highly similar to parent Cu-MOR, which provide duction of platinum and palladium in Cu-MOR initially results
higher activity aer high temperature activation. The benecial in an increasing methanol yield and, aer surpassing an ideal
effect of the added noble metal can stem from agglomeration of M/Cu (M ¼ Pt or Pd) ratio, the yield decrease.
these noble metal precursors and the Cu-species to form
bimetallic Cu-oxo clusters.
HAADF-STEM micrographs show small dispersed clusters
for all PtCu-MOR8.5 materials aer activation at 200 C (Fig. 3
ꢀ
Next, the effect of Pt/Cu-ratio was studied at different and S7†). The material with the least platinum, PtCu-
methane pressures aer activation in oxygen and reaction with MOR8.5(0.02) showed larger particles (ø ¼ 2.2 nm) compared
ꢀ
methane at 200 C followed by off-line extraction with liquid to PtCu-MOR8.5(0.08) (ø
¼
1.1 nm), PtCu-MOR8.5(0.20)
water to test the performance for the isothermal conversion (ø ¼ 0.65 nm) and PtCu-MOR8.5(0.35) (ø ¼ 0.80 nm). However, if
ꢀ
(
Fig. 2, elemental composition in Table S2†). Parent Cu-MOR
6
a sample undergoes 450 C activation, agglomerated particles
ꢁ
1
4
gave a yield of 1.0 mmol g at ambient CH pressure. With were observed, which can be responsible for the low activity
increasing Pt/Cu-ratio the yield increased to 12.5 mmol g for aer high temperature activation (Fig. S12†). Further, powder
PtCu-MOR(0.21), whereaer the yield decreased with increasing X-ray diffraction (PXRD) was carried out for a series of Cu-MOR
ꢁ
1
ꢁ1
Pt/Cu-ratio to yield 3.3 mmol g at Pt/Cu ¼ 1.1. Thus, there is an that was impregnated with different amounts Pt(NH ) (NO )
3
4
3 2
ꢀ
optimal Pt/Cu-ratio providing maximum reactivity. At low Pt/ and dried at 110 C. The materials mostly showed an additional
ꢀ
Cu-ratios the effect of platinum introduction is low, while at reection at about 2q ¼ 13 and further additional peak in case
2 6
higher Pt/Cu undesired agglomerates can be formed during of H PtCl , which consequently comes from a platinum-
36
activation or reaction. In analogy to Cu-MOR, higher methane containing phase (Fig. S8†). These additional reections
pressures (6 and 36 bar) were tested in addition to investigate signicantly decreased in intensity during activation in oxygen
whether for this system higher yields can be achieved with for 2 h at 200 C and did not decrease signicantly within four
ꢀ
ꢀ
higher methane pressures. There is a distinct difference to the further hours of activation at 200 C, indicating that these
reactions performed at 1 bar methane and those at higher corresponding precursors are converted to the active species.
ꢀ
pressures. At 6 bar, the parent Cu-MOR
6
reached a yield of 22.0 Aer a cycle including 200 C activation, methane reaction and
ꢁ
1
ꢁ1
mmol g , which further increased to 31.7 mmol g for PtCu- extraction with liquid water, the reections disappeared in all
6
MOR (0.12), aer which it decreased to minimum of 6.1 mmol cases (Fig. S10†).
ꢁ
1
g
for PtCu-MOR
6
(0.4). At 36 bar, the yield decreased monot-
Copper oxide clusters are the active species for the stepwise
ꢁ1
onously from 43.1 mmol g for the parent Cu-MOR
6
until nally isothermal conversion of methane to methanol at elevated
no methanol was extracted for PtCu-MOR (1.1). These results
6
indicate that an overall benecial result can be obtained using
higher methane pressures (e.g. for PtCu-MOR (0.12)), yet
6
increasing pressures and Pt-loading result in lower yields
compared to the parent Cu-MOR .
6
In the next step, palladium was investigated as the second
metal, as it is known to activate C–H bonds and to undergo
redox reactions with copper. A similar effect to PtCu-MOR was
observed as palladium was introduced. Isothermal activation in
oxygen and reaction in methane gave a maximum methanol
ꢁ
1
yield of 7.2 mmol g for PdCu-MOR (0.3). A slightly lower yield
6
ꢁ
1
(
1
6.5 mmol g ) was obtained for PdCu-MOR(1.0), while Pd/Cu ¼
ꢁ
1
.2 and 3.0 yielded ꢂ2.4 mmol g . The presence of Pd in PdCu-
MOR
6
(0.3) was conrmed by EDX (Fig. S6†). This proves that the
introduction of palladium improves the activity under
isothermal conditions, making the approach of bimetallic oxide
materials for the methane to methanol conversion more
general. A mass spectrometric analysis of the reaction with
PtCu-MOR (0.15) and PdCu-MOR (0.30) revealed the formation
6
6
of a small amount of formaldehyde as only side-product, which
is formed during the extraction of PdCu-MOR (0.30) (Fig. S5†).
The surface composition of PtCu-MOR (0.15) and PdCu-
MOR (0.30) was compared aer activation in oxygen using XPS.
6
6
Fig.
3 HAADF-STEM micrographs of the different PtCu-MOR8.5
ꢁ1
ꢀ
6
materials after activation in a flow of oxygen (50 mL min ) at 200 C
The noble metals are enriched on the surface with a Pt/Cu ratio for 13 h. Scale bar is 20 nm.
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36
methane pressures. PtCu- and PdCu-MOR, however, show showed rather small particles with a mean particle diameter of
higher activity than Cu-MOR, which must in turn be related to 3.2 nm without large agglomerated nanoparticles (Fig. S14†).
the nature of the bimetallic Cu-oxo clusters. On the one hand
Conclusively, we have pioneered the use of PtCu-MOR and
there are clusters, some in the sub-nm range, which allow for PdCu-MOR materials for the stepwise isothermal conversion of
a high fraction of active surface sites. On the other hand, the methane to methanol. Upon platinum- or palladium-
introduction of platinum is reported to facilitate the reduction introduction into the system, the activity aer activation and
ꢀ
of copper, as it is shown by lower reduction temperatures in reaction at 200 C signicantly increased. In contrast to all prior
temperature programmed reduction for PtCu-MOR compared approaches for the stepwise methane to methanol conversion,
43
to the monometallic compounds. Further, the introduction of these materials are more active aer activation at low temper-
platinum into bimetallic PtCu/SiO2 catalysts was reported to ature than aer high temperature activation. Although prom-
44
increase dispersion and reducibility of the copper species.
ising results were obtained, the best yields of Cu-zeolites aer
Thus, besides from the availability of many surface atoms, high temperature activation are still to be reached under
the reducibility seems to be of key importance for activity under isothermal conditions. The character of the bimetallic Cu-oxo
isothermal conditions. This could already be seen by the posi- clusters facilitate reduction of the Cu-oxides, which enables
tive effect of higher methane pressures, which relate to higher reactivity of less activated sites. These bimetallic oxide materials
36
reducing power. For the case of bimetallic oxidized PtCu- and allow for higher activity than other reported materials under
PdCu-MOR it is the reducibility of the bimetallic Cu-oxo clusters isothermal conditions at ambient pressures. We strongly
that is responsible for the increased activity under isothermal believe that this study will stimulate new research and eventu-
ꢀ
conditions. High temperature activation (450 C) resulted in ally such bimetallic oxide materials can be a further step to
larger agglomerates for bimetallic oxide materials, while Cu- nding the holy grail of catalysis.
MOR gave high yields. Under these conditions, Cu-zeolites
form highly active species that easily react even with low pres-
Conflicts of interest
sures of methane. If high pressures of methane are introduced,
these species might easily be reduced to clusters that cannot There are no conicts to declare.
retain the methoxy precursor.
Next, the recyclability of the materials was tested. Extraction
Acknowledgements
in liquid water of PtCu-MOR with Pt/Cu
> 0.32 showed
theory
6
visible Pt-leaching (Fig. S13†). To prevent leaching of Pt to the P. T. thanks Research Foundation – Flanders for a PhD schol-
liquid phase, we investigated successive cycles of activation, arship. V. L. S. acknowledges ESI platform of Paul Scherrer
reaction with methane and steam extraction using PtCu- Institute for the nancial support. S. E. B. acknowledges the
MOR
6 6
(0.15) and also PdCu-MOR (0.3) over four cycles (Fig. 4). A nancial support of Turkish Scientic and Technological
ꢁ
1
¨
˙
stable yield of 6.9–7.4 mmol g for PtCu-MOR
6
(0.15) and 6.5– Research Council (TUBITAK) for the international postdoctoral
.8 mmol g for PdCu-MOR (0.3) was achieved. These yields are scholarship (2219).
similar to those obtained by off-line extraction in liquid water,
ꢁ
1
7
ꢁ1
ꢁ1
which are 8.6 mmol g and 7.2 mmol g , respectively. The
materials are recyclable for at least four cycles. Active PtCu-
Notes and references
ꢀ
MOR
6
(0.15) aer four successive cycles at 200 C, however,
1 E. McFarland, Science, 2012, 338, 340–342.
2
X. Guo, G. Fang, G. Li, H. Ma, H. Fan, L. Yu, C. Ma, X. Wu,
D. Deng, M. Wei, D. Tan, R. Si, S. Zhang, J. Li, L. Sun,
Z. Tang, X. Pan and X. Bao, Science, 2014, 344, 616–619.
P. Tang, Q. Zhu, Z. Wu and D. Ma, Energy Environ. Sci., 2014,
3
4
7
, 2580–2591.
J. P. Lange, K. P. de Jong, J. Ansorge and P. J. A. Tijm, in Stud.
Surf. Sci. Catal., ed. M. de Pontes, R. L. Espinoza, C. P.
Nicolaides, J. H. Scholtz and M. S. Scurrell, Elsevier, 1997,
vol. 107, pp. 81–86.
5
6
7
8
M. Ravi, M. Ranocchiari and J. A. van Bokhoven, Angew.
Chem., Int. Ed., 2017, 56, 16464–16483.
M. Ahlquist, R. J. Nielsen, R. A. Periana and W. A. Goddard
III, J. Am. Chem. Soc., 2009, 131, 17110–17115.
R. A. Periana, D. J. Taube, S. Gamble, H. Taube, T. Satoh and
H. Fujii, Science, 1998, 280, 560–564.
P. Tomkins, M. Ranocchiari and J. A. van Bokhoven, Acc.
Chem. Res., 2017, 50, 418–425.
Fig. 4 Methanol yield after successive cycles of activation in oxygen
ꢀ
9 R. Balasubramanian, S. M. Smith, S. Rawat, L. A. Yatsunyk,
T. L. Stemmler and A. C. Rosenzweig, Nature, 2010, 465,
115–119.
and reaction in methane and extraction using steam at 200
isothermal) at ambient methane pressure for PtCu-MOR
PdCu-MOR (0.3).
C
(
6
(0.15) and
6
170 | Chem. Sci., 2019, 10, 167–171
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1
1
1
0 M. Merkx, D. A. Kopp, M. H. Sazinsky, J. L. Blazyk, J. M u¨ ller 27 A. Sainz-Vidal, J. Balmaseda, L. Lartundo-Rojas and
and S. J. Lippard, Angew. Chem., Int. Ed., 2001, 40, 2782–
807.
E. Reguera, Microporous Mesoporous Mater., 2014, 185, 113–
120.
2
1 G. I. Panov, V. I. Sobolev, K. A. Dubkov, V. N. Parmon, 28 V. L. Sushkevich and J. A. van Bokhoven, Catal. Sci. Technol.,
N. S. Ovanesyan, A. E. Shilov and A. A. Shteinman, React.
Kinet. Catal. Lett., 1997, 61, 251–258.
2 G. I. Panov, K. A. Dubkov, V. I. Sobolev, E. P. Talsi,
M. A. Rodkin, N. H. Watkins and A. A. Shteinman, J. Mol.
Catal. A: Chem., 1997, 123, 155–161.
3 E. V. Starokon, M. V. Parfenov, L. V. Pirutko, S. I. Abornev
and G. I. Panov, J. Phys. Chem. C, 2011, 115, 2155–2161.
4 M. H. Groothaert, P. J. Smeets, B. F. Sels, P. A. Jacobs and
2018, 8, 4141–4150.
29 M. A. Newton, A. J. Knorpp, A. B. Pinar, V. L. Sushkevich,
D. Palagin and J. A. van Bokhoven, J. Am. Chem. Soc., 2018,
140, 10090–10093.
30 A. R. Kulkarni, Z.-J. Zhao, S. Siahrostami, J. K. Nørskov and
F. Studt, ACS Catal., 2016, 6, 6531–6536.
1
1
1
1
31 M. B. Park, S. H. Ahn, A. Mansouri, M. Ranocchiari and
J. A. v. Bokhoven, ChemCatChem, 2017, 9, 3705–3713.
R. A. Schoonheydt, J. Am. Chem. Soc., 2005, 127, 1394–1395. 32 V. L. Sushkevich, D. Palagin, M. Ranocchiari and J. A. van
5 P. J. Smeets, M. H. Groothaert and R. A. Schoonheydt, Catal.
Today, 2005, 110, 303–309.
Bokhoven, Science, 2017, 356, 523–527.
33 V. L. Sushkevich, D. Palagin, M. Ranocchiari and J. A. van
Bokhoven, Science, 2017, 358.
6 J. S. Woertink, P. J. Smeets, M. H. Groothaert, M. A. Vance,
B. F. Sels, R. A. Schoonheydt and E. I. Solomon, Proc. Natl. 34 D. K. Pappas, E. Borfecchia, M. Dyballa, I. A. Pankin,
Acad. Sci. U. S. A., 2009, 106, 18908–18913.
7 N. Beznis, B. Weckhuysen and J. Bitter, Catal. Lett., 2010,
K. A. Lomachenko, A. Martini, M. Signorile, S. Teketel,
B. Arstad, G. Berlier, C. Lamberti, S. Bordiga, U. Olsbye,
K. P. Lillerud, S. Svelle and P. Beato, J. Am. Chem. Soc.,
2017, 139, 14961–14975.
1
1
1
138, 14–22.
8 E. M. Alayon, M. Nachtegaal, M. Ranocchiari and J. A. van
Bokhoven, Chem. Commun., 2012, 48, 404–406.
9 E. M. C. Alayon, M. Nachtegaal, E. Kleymenov and J. A. van
Bokhoven, Microporous Mesoporous Mater., 2013, 166, 131–
35 S. E. Bozbag, E. M. C. Alayon, J. Pech ´a ˇc ek, M. Nachtegaal,
M. Ranocchiari and J. A. v. Bokhoven, Catal.: Sci. Technol.,
2016, 6, 5011–5022.
1
36.
36 P. Tomkins, A. Mansouri, S. E. Bozbag, F. Krumeich,
M. B. Park, E. M. C. Alayon, M. Ranocchiari and J. A. van
Bokhoven, Angew. Chem., Int. Ed., 2016, 55, 5467–5471.
2
2
2
2
0 E. M. C. Alayon, M. Nachtegaal, A. Bodi and J. A. van
Bokhoven, ACS Catal., 2014, 4, 16–22.
1 T. Sheppard, C. D. Hamill, A. Goguet, D. W. Rooney and 37 D. Palagin, A. J. Knorpp, A. B. Pinar, M. Ranocchiari and
J. M. Thompson, Chem. Commun., 2014, 50, 11053–11055. J. A. van Bokhoven, Nanoscale, 2017, 9, 1144–1153.
2 M. J. Wulfers, S. Teketel, B. Ipek and R. F. Lobo, Chem. 38 V. L. Sushkevich, D. Palagin and J. A. van Bokhoven, Angew.
Commun., 2015, 51, 4447–4450. Chem., Int. Ed., 2018, 57, 8906–8910.
3 S. Grundner, M. A. C. Markovits, G. Li, M. Tromp, 39 A. Barcicka and S. Pikus, Zeolites, 1987, 7, 35–37.
E. A. Pidko, E. J. M. Hensen, A. Jentys, M. Sanchez-Sanchez 40 X. Chen, K. M. Engle, D.-H. Wang and J.-Q. Yu, Angew. Chem.,
and J. A. Lercher, Nat. Commun., 2015, 6, 7546.
4 N. Beznis, B. Weckhuysen and J. Bitter, Catal. Lett., 2010, 41 J. T. York, A. Llobet, C. J. Cramer and W. B. Tolman, J. Am.
36, 52–56. Chem. Soc., 2007, 129, 7990–7999.
5 N. V. Beznis, A. N. C. van Laak, B. M. Weckhuysen and 42 A. E. Shilov and G. B. Shul'pin, Chem. Rev., 1997, 97, 2879–
Int. Ed., 2009, 48, 5094–5115.
2
2
1
J. H. Bitter, Microporous Mesoporous Mater., 2011, 138, 176–
83.
6 P. Vanelderen, J. Vancauwenbergh, M.-L. Tsai, R. G. Hadt,
2932.
1
43 S. S. Priya, P. Bhanuchander, V. P. Kumar, S. K. Bhargava and
K. V. R. Chary, Ind. Eng. Chem. Res., 2016, 55, 4461–4472.
2
E. I. Solomon, R. A. Schoonheydt and B. F. Sels, 44 W. Long, P. Liu, Y. Lv, W. Xiong, F. Hao and H. a. Luo, Can. J.
ChemPhysChem, 2014, 15, 91–99. Chem., 2018, 96, 394–403.
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