Hydrogenation of Condensed Aromatic Compounds over Mesoporous Bifunctional Catalysts Following a Diels-Alder Adduct Pathway

Article abstract of DOI:10.1002/cctc.201501295

Pt(0.5 wt %)-Al-SBA-15 and Pt(0.5 wt %)-Al-MCM-41 bifunctional catalysts were prepared by wet impregnation and investigated in the hydrogenation of anthracene and the hydrogenolysis/hydrogenation of a series of synthesized Diels-Alder adducts with anthracene and anthracene derivatives. The mesoporous texture of the investigated catalysts allowed the hydrogenation of these substrates to a large extent. In direct correlation with the size of the Pt particles, Pt-Al-SBA-15 exhibited a higher activity. Both catalysts exhibited a strong Lewis acidity associated with the presence of the Al extra-framework species. The acidity of these catalysts afforded the esterification of the reaction byproduct, that is, succinic anhydride, with methanol or ethanol, and the hydrocracking/decyclization of one hydrogenated ring to lead to 1,2,3,4-tetrahydronaphthalene derivatives. A good correlation with the calculated values of the reaction Gibbs free energy has been evidenced.

Full text of DOI:10.1002/cctc.201501295

DOI: 10.1002/cctc.201501295
Full Papers
Hydrogenation of Condensed Aromatic Compounds over
Mesoporous Bifunctional Catalysts Following a Diels–Alder
Adduct Pathway
[
a]
[b]
[b]
[c]
Pham Thanh Huyen,* Marko Krivec, Marijan Ko cˇ evar,* Ioana C. Bucur,
[d]
[d]
Cristina Rizescu, and Vasile I. Parvulescu*
Pt(0.5 wt%)-Al-SBA-15 and Pt(0.5 wt%)-Al-MCM-41 bifunctional
catalysts were prepared by wet impregnation and investigated
in the hydrogenation of anthracene and the hydrogenolysis/
hydrogenation of a series of synthesized Diels–Alder adducts
with anthracene and anthracene derivatives. The mesoporous
texture of the investigated catalysts allowed the hydrogena-
tion of these substrates to a large extent. In direct correlation
with the size of the Pt particles, Pt-Al-SBA-15 exhibited
a higher activity. Both catalysts exhibited a strong Lewis acidity
associated with the presence of the Al extra-framework spe-
cies. The acidity of these catalysts afforded the esterification of
the reaction byproduct, that is, succinic anhydride, with metha-
nol or ethanol, and the hydrocracking/decyclization of one hy-
drogenated ring to lead to 1,2,3,4-tetrahydronaphthalene de-
rivatives. A good correlation with the calculated values of the
reaction Gibbs free energy has been evidenced.
Introduction
In the past decades, the depletion of the fossil reserves has ori-
entated oil processing towards heavier petroleum crudes that
hydrogenation of two- and one-ring aromatic compounds con-
siderably.
[1]
include polycyclic aromatic molecules. The presence of these
components in diesel products raises important environmental
The interaction of anthracene with metal surfaces during hy-
drogenation has been investigated by both IR spectroscopic
[2]
[5]
[6]
[5]
concerns, and the public demands cleaner fuels. Therefore,
a solution to decrease/eliminate the content of polycyclic aro-
matic molecules, that is, to decrease the aromatic content, is
the hydrogenation of these feedstocks.
studies
and theoretical calculations.
IR spectroscopy
showed that the surface complexes diminish gradually in
amount during successive hydrogenation and dehydrogena-
tion cycles, and the spectra of stable partially dehydrogenated
species are consistent with the rearomatization of only one
end ring. DFT calculations of polycyclic aromatic hydrocarbons
on transition metal surfaces support these findings and re-
vealed that the best adsorption structure is associated with ar-
omatic rings on bridging sites with increasing adsorption ener-
gies per molecule. Upon adsorption, the molecules are distort-
ed, which implies a modification of the energy level and the
shape of molecular orbitals, and hence ensures a better mole-
However, the hydrogenation of these molecules is not
simple and is influenced strongly by the nature of the catalyst.
Among other factors, it is controlled by the inhibition of differ-
ent aromatic compounds, which has been demonstrated for
[
3]
[1b,4]
both noble and nonmetal catalysts.
As an effect of com-
petitive adsorption, three-ring aromatic compounds inhibit the
[
a] Prof. P. T. Huyen
[
6]
Department of Organic and Petrochemical Technology
School of Chemical Engineering
Hanoi University of Science and Technology
cule–surface stabilizing interaction. Calculations performed
on Pt(111) suggested that this competition is dominated by
the electronic interaction and hence a stronger distortion is
obtained for a strong interaction.
1
Dai Co Viet, Hanoi (Vietnam)
E-mail: huyen.phamthanh@hust.edu.vn
The catalysts reported to date for the hydrogenation of an-
[
b] Dr. M. Krivec, Prof. M. Ko cˇ evar
Faculty of Chemistry and Chemical Technology
University of Ljubljana
[
5]
thracene are diverse. Monometallic silica-supported Pt, hydro-
[
4]
processing presulfided CoMo/Al O , and NiMo/Al O3 and
2
3
2
Ve cˇ na pot 113, SI-1000 Ljubljana (Slovenia)
E-mail: marijan.kocevar@fkkt.uni-lj.si
[1b,7]
NiW/Al O3
are among the most utilized, the selectivities of
which are controlled by the factors discussed above. NiMo/
Al O and NiW/Al O have the advantage of bifunctionality, in
2
[
c] Dr. I. C. Bucur
National Institute of Materials Physics
Atomistilor 105b, 077125 Magurele-Ilfov (Romania)
2
3
2
3
which the metal function promotes hydrogenation and the
acidic function promotes isomerization, ring opening, and
[
d] C. Rizescu, Prof. V. I. Parvulescu
Department of Organic Chemistry, Biochemistry and Catalysis
University of Bucharest
Blv. Regina Elisabeta 4-12, Bucharest 030016 (Romania)
E-mail: vasile.parvulescu@chimie.unibuc.ro
dealkylation. Ni-MoS supported on carbon nanofibers has also
2
been investigated as a hydrogenation catalyst for this reac-
[
8]
tion. Catalysts prepared with the support functionalized by
a less severe treatment led to short and defective MoS slabs
Supporting Information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201501295.
2
and a higher hydrogenation activity, whereas a harsher func-
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tionalization treatment led to the formation of long stacked
this case, the terminal rings were hydrogenated more rapidly
[
19]
MoS slabs and lower performance towards anthracene hydro-
than the interior ring.
2
genation.
In another direction, almost 80 years ago, Diels and Thiele
noted the unusual stability of the maleic anhydride cycload-
duct and employed this feature to scavenge anthracene gener-
Homogeneous reactions that use Ru-based catalysts and
a series of anthracene derivatives occurred under mild condi-
[
9]
[20]
tions and led to the hydrogenation of only the external rings.
ated in a retro-[4+2] reaction. The Diels–Alder cycloaddition
The introduction of ring substituents at C-9 did not impede
the hydrogenation of the external aromatic rings. In contrast,
substitution of one of the external rings with a functional
group (at least a methyl group) makes this ring unattractive
for coordination to the metal center, and hence resistant to hy-
drogenation. Very close conclusions with regard to the selectiv-
ity for the preservation of an interior benzene ring were drawn
with hydrogen activated by lithium and potassium organo-
amides, in which the catalytic properties of the strong bases
depend on the nature of the organic ligands in the dialkyl-
reaction (see, for example, Ref. [21] and references therein) of
anthracene with dienophiles is a reversible, temperature-de-
[
22]
pendent reaction, and the hydrogenation of the resulting
adduct was considered to prevent the pyrolytic reversal reac-
tion and to produce compounds of a higher thermal stability.
Indeed, experiments performed with Ru/Al O3 and Raney-Ni
2
catalysts led to the hydrogenation of the external rings, which
thus left the adduct unaltered.
The aim of this study was to investigate the processing of
the polycyclic aromatic molecules contained in heavy petrole-
um crudes by combining the Diels–Alder synthesis of a cycload-
duct with successive hydrogenation. The fragmentation of
these heavy molecules to small cycloalkanes represented a sec-
ondary goal. For this purpose, anthracene and substituted an-
thracene derivatives were considered as probe molecules, and
new bifunctional mesoporous Pt-Al-SBA15 and Pt-Al-MCM-41
were used as catalysts.
[10]
amide and the corresponding metal cations. Other studies in
which active carbon afforded hydrogen transfer using molecu-
lar hydrogen indicated that it is possible to change the reac-
tion pathway to provide the hydrogenation of the central ring
[
11]
to a high extent.
The effect of the hydrogen source has also been demon-
[12]
strated by several authors. Zhang et al. investigated the hy-
drogenation of anthracene using hydrogen gas or the hydro-
gen donor tetralin as hydrogen sources and the combination
of both in the presence of activated carbon and Ni/C as cata-
lysts. An apparent improvement in both the conversion and
product distribution was determined if tetralin and hydrogen
gas were used together. In the absence of hydrogen gas, the
active carbon facilitates hydrogen transfer from tetralin to an-
thracene, whereas the metal mainly transferred hydrogen from
the gas phase to anthracene. Research on Au and Ag nanopar-
ticles (NPs) emphasized the role of the hydride anions in the
Results
Textural characterization
The textural characteristics of the investigated catalysts are
presented in Table 1. The measured values for the pure sup-
ports are typical for such materials. The deposition of Pt had
different effects. For MCM-41, the deposition of Pt led to a de-
crease of the surface area that occurred at the level of micro-
pores (Figures S1 and S2). A small decrease of the pore volume
was also evidenced. For the SBA-15 support, the decrease of
the surface area was less important and merely associated
with the decrease of the surface of the micropores. However,
for this catalyst an important decrease of the pore size was de-
termined. Moreover, the deposition of Pt led to a bimodal pore
distribution with mesopores of 39 and 62 Š, respectively (Fig-
ures S3 and S4).
[
13]
same reaction. Hydride formed from NaBH was trapped by
4
surfactants that stabilized the NPs and was then transferred to
the NPs surface. Spectroscopic investigations demonstrate that
the metal NPs play a nanoelectrode role by storing electrons
from hydrides, and the resulting hydrogen radical then reacts
with anthracene. This mechanism is supported by theoretical
calculations that indicate that the gold cluster hydride anion is
[
14]
of lower energy than the corresponding neutral cluster.
However, this process requires an optimum size of Au (3–
5
nm) and Ag (ꢀ3 nm). The effect of the particle size was also
confirmed for Rh NPs. Although 5 nm tetrahedral Rh NPs on
charcoal provided the hydrogenation of the external rings of
anthracene, the commercial Rh/C catalyst led to a high extent
XRD characterization
Diffractograms of the investigated catalysts are presented in
Figure 1. In the absence of Pt, the XRD patterns showed typical
reflections for these materials. No reflections of Pt were detect-
[15]
of internal-ring hydrogenation. The deposition of Rh NPs (3–
nm) onto silica-coated magnetite NPs (Fe O @SiO ) did not
5
3
4
2
[16]
change this behavior but improved the recoverability.
A very similar behavior was exhibited by carbon-supported
[
17]
Table 1. Textural characteristics of the investigated catalysts.
Pd (5 nm) NPs. Pd NPs (2–10 nm) stabilized in high-density-
polyethylene were also investigated in the catalytic hydrogena-
Sample
BET surface t-plot micropore
area [m g ] surface area [m g ] [cm g
Pore volume Pore size
2
À1
2
À1
3
À1
]
[Š]
tion of anthracene in supercritical CO (200 atm with 10 atm of
2
H ) by in situ UV/Vis spectroscopy. Kinetic studies confirmed
Al-MCM-41
912
748
673
289
255
1.14
0.90
1.04
0.79
29
28
90
39, 62
2
that in the presence of the NPs the initial hydrogenation
Pt-Al-MCM-41 822
Al-SBA-15 697
Pt-Al-SBA-15 684
[18]
occurs mainly at the external rings. However, the deposition
of Pd on g-alumina led to a different behavior to that of Rh. In
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ed in these patterns after its deposition, which suggests the
presence of small particles that are highly dispersed.
to the 8a and 19b modes of Py in interaction with Brønsted
À1
acid sites (Py–B) were detected at n˜ =1636 and 1540 cm .
Compared to that of the bands assigned to Py–L species, the
intensity of the bands assigned to Py–B was low for both cata-
H chemisorption
2
À1
lysts. Clearly, the intensity of the band at n˜ =1542 cm is also
The H2 chemisorption and H2 temperature-programmed de-
sorption (TPD) results are given in Table 2. These results dem-
onstrate that the deposition of Pt occurs with a different dis-
persion and the formation of particles with a different average
diameter. On Al-MCM-41 the dispersion is very high (83%),
which corresponds to particles with diameters smaller than
sensitive to the chemical composition, and the low intensity of
these bands reflects a very small population of OH groups. The
À1
two other bands at n˜ =1576 and 1490 cm are assigned to Py
[
23]
adsorbed (Py-ad) on either Lewis or Brønsted acid sites. Gen-
À1
erally, the band located at around n˜ =1490 cm is not dis-
cussed in the literature because it characterizes the interaction
of Py with both Lewis and Brønsted acid sites. However, the
variation of this band with temperature parallels that of Py–L,
which confirms the acidity generated by the presence of the
extra-framework Al species.
2
nm. Differently, on SBA-15 the dispersion is much lower
(
15.6%) and the average diameter is approximately five times
higher. However, there were no differences in the H -TPD re-
2
sults that may account for the presence of some hydrogen
spillover facilitated by the acid sites generated by Al.
X-ray photoelectron spectroscopy
TEM measurements
The X-ray photoelectron spectroscopy (XPS) spectra are shown
in Figure 4, and the binding energies (BEs) of the investigated
levels are compiled in Table 3. The Pt4f7/2 level overlaps the
Al2p level, and the deconvolution of the band led to the
values presented in Table 3 (Figure 4A). According to the litera-
TEM pictures of the investigated catalysts confirm the conclu-
sions drawn from the results of XRD and H chemisorption
2
(
Figure 2). Pt is better dispersed on Al-MCM-41 than on Al-SBA-
5 (Figure 2). The histograms presented in Figure 2 show that
1
0[25]
over 80% of the analyzed particles are smaller than 3 nm. For
Pt-Al-SBA-15, the frequency of the particles larger than 4 nm is
almost 30%.
ture, the deconvoluted binding energies correspond to Pt
III [26]
and Al . Deconvolution of the oxygen band (Figure 4B) re-
vealed the presence of three components (Table 3), the first at
[
27]
The FTIR spectra with absorbed pyridine (Py) as a probe
BE=532 eV, typical of oxygen in molecular sieves,
the
(
Figure 3) show typical absorption bands assigned to the 8a
second at BE=533 eV, typical of oxygen incorporated into
[
28]
and 19b vibration modes of adsorbed Py that forms Lewis-
SiO2, and the last at BE=530 eV, which better approaches
À1
[29]
type adducts (Py–L) with bands at n˜ =1622 and 1453 cm .
the binding energy of oxygen in dispersed aluminum oxide.
À1
The band at n˜ =1453 cm is very sensitive to the chemical
The Si band was also deconvoluted into three components
(Figure 4C, Table 3) that all correspond to Si bound to O spe-
[
23]
composition and, for the materials that contain Al, is typical
[24]
[30]
of the extra-framework species. Absorption bands assigned
cies.
Figure 1. XRD patterns of A) Al-SBA-15, B) Pt-Al-SBA-15, and C) Pt-Al-MCM-41.
Table 2. H
2
chemisorption and H
Metal
2
-TPD results.
Sample
H
2
chemisorption
H
2
-TPD
Metallic surface
Metallic surface
Active particle
diameter [nm]
Chemisorbed H
at 1308C [mmol]
2
desorbed
2
Interfacial H desorbed
2
À1
2
À1
dispersion [%]
area [m gsample
]
area [m gmetal
]
at 2408C [mmol]
Pt-Al-MCM-41
Pt-Al-SBA-15
83.0
15.6
2.05
0.38
205.09
38.48
1.4
7.3
11
11
0.4
0.3
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The reaction occurred with a high selectivity to dihydroanthra-
cene. To small extents, 1,2,3,4,5,6,7,8-octahydroanthracene and
1
,2,3,4,4a,9,9a,10-octahydroanthracene were produced as well.
The hydrogenation of 1,2,3,4,5,6,7,8-octahydroanthracene and
,2,3,4,4a,9,9a,10-octahydroanthracene continued to perhy-
1
droanthracene only in traces on Pt-Al-SBA-15.
The results of the catalysis of the hydrogenation of sub-
strates 3a–e are compiled in Table 5. The reaction proceeded
with the formation of succinic anhydride and a mixture of hy-
drogenated di-, octa-, and perhydroanthracene derivatives. Di-
hydroanthracenes were the major compounds in these hydro-
genations. Under the investigated reaction conditions, the
total conversion of the cycloadducts was achieved. However,
the degree of hydrogenation of the investigated molecules de-
pended on the catalyst. Thus, Pt-Al-SBA-15 afforded a more ad-
vanced hydrogenation of the aromatic rings than Pt-Al-MCM-
4
1. In the case of 3a, besides perhydroanthracene, tetralin was
also produced, although with a low selectivity (13.3%). For the
other substrates, the hydrogenation stopped at the octahy-
droanthracene derivatives. The exception was 3e on Pt-Al-
MCM-41, for which the reaction stopped at the dihydroanthra-
cene.
Figure 2. TEM pictures and particle size distribution of Pt-Al-SBA-15 (top)
and Pt-Al-MCM-41 (bottom).
Catalytic behavior
Except substrate 3d, in all the other cases, the octahydroan-
thracene derivatives suffered a hydrocracking/decyclization re-
action with the formation of tetrahydronaphthalene deriva-
The results of the catalysis of the hydrogenation of anthracene
over Pt-Al-SBA-15 and Pt-Al-MCM-41 are presented in Table 4.
Figure 3. Py-FTIR spectra of A) Pt/Al-SBA-15 at a) RT under vacuum, b) 1508C, c) 2508C, and d) 3508C and B) Pt/Al-MCM-41 at a) 1508C, b) 2508C, and
c) 3508C.
Figure 4. A) XPS spectra of the investigated catalysts at the Pt4f7/2 and Al2p levels. B) XPS spectra of the investigated catalysts at the O1s level. C) XPS spectra
of the investigated catalysts at the Si2p level.
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Discussion
Table 3. Binding energies of the Pt4f7/2, Al2p, O1s, and Si2p levels.
Catalyst
BE [eV]
Al2p
The mesoporous texture of the investigated catalysts allowed
the hydrogenation of both anthracene and the hydrogenoly-
sis/hydrogenation of various Diels–Alder adducts.
Pt4f7/2
71.1
O1s
Si2p
Pt-SBA-15
Pt-MCM-41 71.1
530.4 531.8 533.5 73.5 100.8 102.2 103.7
530.4 532.1 533.3 73.8 100.8 102.2 103.7
The routes of the hydrogenation of anthracene and the hy-
drogenolysis/hydrogenation of intermediate Diels–Alder ad-
ducts in connection to the calculated reaction Gibbs free ener-
[
33]
gies are depicted in Schemes 1–3. Irrespective of the extent
of hydrogenation, the Diels–Alder route is energetically more
favorable to achieve the hydrogenated products, which is also
in perfect agreement with the catalytic results obtained in this
study. Although the hydrogenation of the condensed aromatic
compounds proceeded in a first step through a parallel reac-
tives. However, decyclization reactions on Pt/Al O catalysts
2
3
[31]
were reported a long time ago. Besides this, the Pt-Al-SBA-
5 catalyst is able to continue hydrocracking/decyclization, to
1
a small extent, with a hydrocracking step. No further decycliza-
tion or coking was determined on these catalysts. Elemental
analysis of the spent catalysts indicated a carbon content
lower than 1 wt%.
[
4]
tion both on the inner and outer rings, the Diels–Alder
adduct route corresponds to a consecutive pathway in which
the inner ring undergoes hydrogenation first.
The time evolution of the conversion and selectivity in the
hydrogenation of anthracene and Diels–Alder adducts over Pt/
Al-SBA-15 and Pt/Al-MCM-41 catalysts is presented in Figure 5.
This evolution confirms that 9,10-dihydroanthracene deriva-
tives are the first intermediate in the hydrogenation of both
kinds of substrates. A similar tendency was determined for the
other adducts as well.
In all cases, Pt-Al-SBA-15 was superior to Pt-Al-MCM-41 to
afford not only the hydrogenolysis of the adducts but also the
hydrogenation of the resulting aromatic rings to a higher
extent. Although it was deposited using an identical proce-
dure, Pt had different dispersions and particle sizes on the two
supports (Table 2, Figure 2). On Al-SBA-15, the particles were
larger and the dispersion lower than those on Al-MCM-41. XPS
The hydrogenation of substrates 3a–c led to the formation
of succinic anhydride as a byproduct. However, to make the
composition of the hydrogenated feedstock more compatible
with fuel characteristics, it was further reacted with either
[
32]
methanol or ethanol to generate the corresponding diesters.
This reaction took the advantage of the acidity of the Al-SBA-
1
5 and Al-MCM-41 supports (Figure 3).
The analysis of the reaction products evidenced that esterifi-
cation occurred with total conversions and some differences
were generated by the nature of the alcohol. With methanol,
the esterification led to selectivities to succinate dimethyl ester
in the range of 70–90%, whereas with ethanol, the esterifica-
tion was almost totally toward the diethyl ester.
Scheme 1. Hydrogenation of anthracene to 9,10-dihydroanthracene by two
parallel routes.
Table 4. Hydrogenation of anthracene over Pt-Al-SBA-15 and Pt-Al-MCM-41 (0.1 mg Pt, substrate/Pt molar ratio of 20:1, 5.0 mL heptane, 1008C, 100 bar
, 12 h).
H
2
Catalyst
Conversion [%]
Selectivity [%]
9,10-Dihydroanthracene
1,2,3,4,5,6,7,8-Octa-
hydroanthracene
1,2,3,4,4a,9,9a,10-Octa-
hydroanthracene
Perhydroanthracene
Pt-Al-SBA-15
Pt-Al-MCM-41
100
100
71.7
91.3
7.2
4.7
20.9
4.0
0.2
0
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2
Table 5. Hydrogenation of 3a–e over Pt-Al-SBA-15 and Pt-Al-MCM-41 (0.1 mg Pt, substrate/Pt molar ratio of 20:1, 5.0 mL heptane, 1008C, 30 bar H , 12 h).
Catalyst
Conversion [%]
Selectivity [%]
1,2,3,4,4a,9,9a,10-Octa-
9,10-Dihydro-
Perhydro-
Tetralin
anthracene
hydroanthracene
anthracene
Pt-Al-SBA-15
Pt-Al-MCM-41
100
100
61.5
77.3
18.1
12.7
7.1
10.0
13.3
0
Catalyst
Conversion [%]
Selectivity [%]
9
-Methyl-9,10-dihydro-
9-Methyl-1,2,3,4,4a,9,9a,10-octa-
hydroanthracene
1-Methyl-1,2,3,4-tetra-
hydroanthracene
anthracene
Pt-Al-SBA-15
Pt-Al-MCM-41
100
100
75.2
89.0
12.1
9.4
12.7
1.6
Catalyst
Conversion [%]
Selectivity [%]
9-Ethyl-1,2,3,4,4a,9,9a,10-octa-
hydroanthracene
9
-Ethyl-9,10-dihydro-
9-Ethyl-1,2,3,4-tetra-
hydroanaphthalene
anthracene
Pt-Al-SBA-15
Pt-Al-MCM-41
100
100
77.2
81.7
10.6
8.1
12.2
10.2
Catalyst
Conversion [%]
Selectivity [%]
9-Methyl-9,10-dihydro-
9-Methyl-1,2,3,4,4a,9,9a,10-octa-
anthracene
hydroanthracene
Pt-Al-SBA-15
Pt-Al-MCM-41
100
100
95.1
97.0
4.9
3.0
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Table 5. (Continued)
Catalyst
Conversion [%]
Selectivity [%]
2-Ethyl-1,2,3,4,4a,9,9a,10-octa-
hydroanthracene
2
-Ethyl-9,10-dihydro-
7-Ethyl-1,2,3,4-tetra-
hydroanaphthalene
anthracene
Pt-Al-SBA-15
Pt-Al-MCM-41
100
100
94.6
100.0
3.5
0
1.9
0
investigation of these catalysts (Figure 4) confirmed the exten-
the reaction products, but analysis of the gas phase in the au-
0
sive reduction of Pt to Pt .
toclave identified C fragments.
4
In addition to the hydrogenation of the aromatic rings of an-
thracene and of fragments that resulted from the hydrogenoly-
sis of the Diels–Alder adducts, because of their bifunctional
character, the investigated catalysts were able to catalyze the
direct esterification of the succinic anhydride byproduct to
either mono- or diesters. The detected acidity also favored the
disruption of one cycle by a hydrocracking/decyclization reac-
tion with the formation of hydronaphthalene derivatives. No
other alkyl derivatives of hydronaphthalene were identified in
The acidic function of these catalysts was allowed by the in-
sertion of Al in both the SBA-15 and MCM-41 networks. Py-
FTIR spectra indicated that this process generated enough
strong Lewis acid centers to be detectable after the desorption
of Py at 3508C.
None of the analyses performed (chromatographic or spec-
troscopic) indicated the formation of any tarry phase. The cata-
lysts were recycled three times after washing with n-hexane.
No changes in the performances were detected, and this be-
Figure 5. Time evolution of the conversion and selectivity in the hydrogenation of A, B) anthracene and C,D) Diels–Alder adducts over A, C) Pt/Al-SBA-15 and
B,D) Pt/Al-MCM-41 (0.1 mg Pt, substrate/Pt molar ratio of 20:1, 5.0 mL heptane, 1008C, 30 bar H ).
2
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Experimental Section
Synthesis and characterization of cycloadducts 3
Cycloadducts 3a–e were prepared in good-to-excellent yields (90–
9
1
3%) by the Diels–Alder reaction between anthracene derivatives
a–e and maleic anhydride (2) according to a modification of a de-
[34]
scribed procedure. The analytical and spectroscopic data of the
known products were identical to those reported previously
(
Table 6).
Table 6. Synthesis of anthracene/maleic anhydride cycloadducts 3a–e.
Scheme 2. Hydrogenation of anthracene to 1,2,3,4,5,6,7,8-octahydroanthra-
cene by two parallel routes.
[a]
[b]
Entry
Starting material
Product
t [min]
Yield [%]
1
2
R
R
1
2
3
4
5
1a
1b
1c
1d
1e
H
Me
CH=CH
CHO
H
H
H
H
H
Et
3a
3b
3c
3d
3e
30
30
150
240
60
90
90
93
93
91
2
[a] Heating to reflux in xylene. [b] Yield of isolated products.
Scheme 3. Hydrogenation of anthracene to tetradecahydroanthracene (per-
hydroanthracene) by two parallel routes.
A suspension of 1 (1 mmol) and 2 (1.1 mmol) was heated to reflux
in xylene (mixture of isomers; 3 mL). The reaction was followed by
TLC, and after completion the reaction mixture was cooled. The
precipitated solid was collected by filtration, washed with MeOH,
and dried. The crude products 3a–e were recrystallized from ap-
propriate solvents. Melting points were determined by using
havior could be associated with the absence of repolymeriza-
tion. However, it is clear that three times is not enough, and
therefore, these catalysts are still under investigation in related
reactions in which we are looking for long-term recycling.
1
a Kofler micro hot stage. H NMR spectra were recorded by using
a Bruker Avance Ultrashield 500 plus spectrometer at 298C and
13
5
00 MHz using TMS as an internal standard. C NMR spectra were
recorded by using the same instrument at 125 MHz and are refer-
enced against the central line of the solvent signal ([D ]DMSO
6
Conclusions
septet at d=39.5 ppm). The coupling constants (J) are given in Hz.
NMR peak assignments are based on HSQC and HMBC 2D NMR
spectra. IR spectra were obtained by using a Bruker FTIR Alpha
Platinum attenuated total reflectance (ATR) spectrometer. MS spec-
tra were recorded by using an Agilent 6224 Accurate Mass TOF LC/
MS system. Elemental analysis (C, H, N) was performed by using
a PerkinElmer 2400 Series II CHNS/O Analyzer. TLC was performed
with Fluka silica gel TLC cards.
The deposition of Pt (0.5 wt%) on Al-SBA-15 and Al-MCM-41
supports led to bifunctional catalysts with different metal dis-
persions. Pt-Al-SBA-15 contained larger Pt particles than Pt-Al-
MCM-41. Both catalysts exhibited a quite strong Lewis acidity
associated with the presence of the Al extra-framework spe-
cies. To evaluate these catalysts, in addition to anthracene, we
synthesized a series of adducts according to the Diels–Alder
protocol. The mesoporous texture of the investigated catalysts
allowed the hydrogenation of anthracene and the hydrogenol-
ysis/hydrogenation of various Diels–Alder adducts. In direct
correlation with the size of the Pt particles, Pt-Al-SBA-15 afford-
ed higher conversions in the hydrogenation of both anthra-
cene and the Diels–Alder adducts. The strong Lewis acidity of
these catalysts also afforded the esterification of the reaction
byproduct, that is, succinic anhydride, with methanol or etha-
nol and a hydrocracking/decyclization reaction.
Characterization of products
[35]
9
,10-Dihydro-9,10-[3,4]furanoanthracene-12,14-dione (3a)
Yield: 249 mg (90%) as a white solid; m.p. 274–2758C (from
[5a]
EtOAc), lit. m.p. 260–2628C (benzene);
IR (ATR): n˜ max =3069,
The results obtained in the hydrogenation of anthracene
and its various Diels–Alder adducts confirmed the values of
the reaction Gibbs free energy, which indicates that the adduct
route is more energetically favorable.
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À1
3
045, 3021, 2977, 1834, 1767, 1465, 1457, 1234, 1218, 1077 cm
;
12,14-Dioxo-9,10-[3,4]furanoanthracene-9(10H)-carbaldehyde
(3d)
1
[37]
H NMR (500 MHz, [D ]DMSO): d=3.66 (s, 2H, 11-H, 15-H), 4.88 (s,
H, 9-H, 10-H), 7.18 (m, 4H), 7.33 (m, 2H), 7.47 ppm (m, 2H) (1-H,
-H, 3-H, 4-H, 5-H, 6-H, 7-H, 8-H); C NMR (125 MHz, [D ]DMSO):
6
6
2
2
1
3
d=44.3 (9-C, 10-C), 47.9 (11-C, 15-C), 124.5 (Ar), 124.8 (Ar), 126.5
Ar), 127.1 (Ar), 139.1 (Ar), 141.1 (Ar), 171.5 ppm (CO); MS (ESI+):
(
+
+
m/z=277 [M+H] ; HRMS calcd for C H O : 277.0865 [M+H ];
1
8
13
3
found: 277.0857.
9
-Methyl-9,10-dihydro-9,10-[3,4]furanoanthracene-12,14-dione
[36]
(3b)
Yield: 283 mg (93%) as an off-white solid; m.p. 246–2478C
[
37]
(
xylene), lit. m.p. 238–2398C (benzene);
IR (ATR): n˜ max =3061,
À1
2
947, 2883, 2769, 1863, 1767, 1716, 1457, 1224, 1215, 1068 cm
H NMR (500 MHz, [D ]DMSO): d=3.79 (dd, J =3.3 Hz, J =9.2 Hz,
;
1
6
1
2
1
H, 15-H), 4.31 (d, J=9.2 Hz, 1H, 11-H), 4.95 (d, J=3.3 Hz, 1H, 10-
H), 7.14 (m, 1H), 7.20 (m, 1H), 7.28 (m, 3H), 7.42 (m, 1H), 7.58 (m,
H), 7.70 (m, 1H) (1-H, 2-H, 3-H, 4-H, 5-H, 6-H, 7-H, 8-H), 10.83 ppm
1
13
(
(
(
(
s, 1H, CHO); C NMR (125 MHz, [D ]DMSO): d=44.6 (10-C), 48.4
15-C), 48.7 (11-C), 57.0 (9-C), 122.9 (Ar), 123.4 (Ar), 125.2 (Ar), 125.5
Ar), 126.6 (Ar), 127.2 (Ar), 127.4 (Ar), 127.6 (Ar), 136.9 (Ar), 138.77
6
Yield: 261 mg (90%) as a white solid; m.p. 269–2718C (xylene), lit.
Ar), 138.81 (Ar), 141.0 (Ar), 170.85 (CO), 170.94 (CO), 201.6 ppm
[
36]
m.p. 269–2708C (xylene); IR (ATR): n˜ =2963, 1860, 1829, 1771,
+
max
(CHO); MS (ESI+): m/z=305 [M+H] ; HRMS calcd for C H O :
305.0814 [M+H ]; found: 305.0819.
1
9
13
4
À1
1
1
2
458, 1231, 1210, 1068 cm
.16 (s, 3H, Me), 3.33 (d, J=9.0 Hz, 1H, 11-H), 3.70 (dd, J =3.3 Hz,
;
H NMR (500 MHz, [D ]DMSO): d=
+
6
1
J2 =9.0 Hz, 1H, 15-H), 4.85 (d, J=3.3 Hz, 1H, 10-H), 7.22 (m, 4H),
.33 (m, 2H), 7.41 (m, 1H), 7.49 ppm (m, 1H) (1-H, 2-H, 3-H, 4-H, 5-
7
2
-Ethyl-9,10-dihydro-9,10-[3,4]furanoanthracene-12,14-dione
1
3
H, 6-H, 7-H, 8-H); C NMR (125 MHz, [D ]DMSO): d=14.6 (Me), 44.2
[38]
6
(3e)
(
10-C), 44.3 (9-C), 49.3 (15-C), 51.7 (11-C), 122.05 (Ar), 122.08 (Ar),
1
1
24.1 (Ar), 124.8 (Ar), 126.40 (Ar), 126.44 (Ar), 126.9 (Ar), 127.0 (Ar),
39.1 (Ar), 141.3 (Ar), 141.6 (Ar), 143.6 (Ar), 170.5 (CO), 171.4 ppm
+
(
CO); MS (ESI+): m/z=291 [M+H] ; HRMS calcd for C H O :
19
15
3
+
2
91.1021 [M+H ]; found: 291.1024.
9
-Vinyl-9,10-dihydro-9,10-[3,4]furanoanthracene-12,14-dione
(3c)
Yield: 277 mg (91%) as a white solid; m.p. 257–2588C (toluene), lit.
[38]
m.p. 256–2578C (benzene);
847, 1771, 1472, 1231, 1212, 1075 cm
D ]DMSO): d=1.10 (t, J=7.6 Hz, 3H, CH CH ), 2.54 (q, J=7.6 Hz,
IR (ATR): n˜ =2964, 2928, 2867,
max
À1
1
1
;
H NMR (500 MHz,
[
6
2
3
2
H, CH CH ), 3.64 (m, 2H, 11-H, 15-H), 4.83 (s, 2H, 9-H, 10-H), 7.02
2 3
(
m, 1H), 7.16 (m, 3H), 7.23 (m, 1H), 7.46 ppm (m, 2H) (1-H, 3-H, 4-
13
H, 5-H, 6-H, 7-H, 8-H); C NMR (125 MHz, [D ]DMSO): d=15.6
6
(
CH CH ), 27.9 (CH CH ), 44.0, 44.4 (9-C, 10-C), 47.9, 48.0 (11-C, 15-
2 3 2 3
C), 124.29 (Ar), 124.33 (Ar), 124.4 (Ar), 124.7 (Ar), 126.2 Ar), 126.4
(
(
Ar), 126.5 (Ar), 136.4 (Ar), 139.1 (Ar), 141.2 (Ar), 141.4 (Ar), 142.7
Yield: 281 mg (93%) as a white solid; m.p. 247–2488C (xylene); IR
+
Ar), 171.55 (CO), 171.59 ppm (CO); MS (ESI+): m/z=305 [M+H] ;
(
ATR): n˜ =2965, 1857, 1776, 1465, 1457, 1221, 1211, 1068,
max
À1
+
1
HRMS calcd for C H O : 305.1178 [M+H ]; found: 305.1176.
1
054 cm ; H NMR (500 MHz, [D ]DMSO): d=3.71 (dd, J =3.0 Hz,
20 16
3
6
1
J2 =9.0 Hz, 1H, 15-H), 3.90 (d, J=9.0 Hz, 1H, 11-H), 4.90 (d, J=
.0 Hz, 1H, 10-H), 5.79 (d, J=17.8 Hz, 1H, CH =CH), 6.06 (d, J=
3
2
Catalyst synthesis
1
1.3 Hz, 1H, CH =CH), 6.77 (d, J =11.3 Hz, J =17.8 Hz, 1H, CH =
2 1 2 2
CH), 7.23 (m, 4H), 7.36 (m, 3H), 7.52 ppm (m, 1H) (1-H, 2-H, 3-H, 4-
Al-SBA-15 was synthesized according to the following procedure.
P123 (3.5 g) was dissolved in 1.5m HCl (100 mL) under vigorous
stirring. Then, aluminum sulfate (0.6 g) was added, and the solution
was stirred for 1 h. Tetraethyl orthosilicate (TEOS; 8.5 g) was added
dropwise, and the solution was maintained at RT for 15 h and then
at 408C for 24 h. The resulting suspension was transferred into an
autoclave and crystallized at 908C for 48 h. The obtained solid
product was collected by filtration, washed with doubly distilled
1
3
H, 5-H, 6-H, 7-H, 8-H); C NMR (125 MHz, [D ]DMSO): d=44.4 (10-
6
C), 48.8 (11-C), 49.0 (15-C), 51.4 (9-C), 121.6 (CH =CH), 123.0 (Ar),
2
1
1
23.6 (Ar), 124.2 (Ar), 125.1 (Ar), 126.3 (Ar), 126.8 (Ar), 127.0 (Ar),
27.1 (Ar), 132.1 (CH =CH), 138.6 (Ar), 140.3 (Ar), 141.0 (Ar), 142.6
2
(
Ar), 169.7 (CO), 171.2 ppm (CO); elemental analysis calcd (%) for
C H O (MS (ESI+):
20
14
3
+
m/z=302 [M+H] ): C 79.46, H 4.67; found: C 79.48, H 4.44.
water, dried, and calcined at 5508C for 6 h (heating rate of
À1
1
8Cmin ). Al-MCM-41 was synthesized according to a procedure
[39]
reported by Beck et al.
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The deposition of Pt (0.5 wt%) on these supports was performed
by a wet impregnation methodology. H PtCl (0.11 g) dissolved in
correction was made with the C1s photopeak of adventitious
carbon (CÀC or CÀH bonds) located at BE=284.8 eV. The atomic
surface compositions were calculated using the sensitivity factors
provided with the apparatus software, applied to the surface
below the corresponding fitted XPS signals. An estimated error of
Æ0.1 eV of the BE values was assumed for all measurements.
2
6
water (10 mL) was added to a suspension of the support (1 g; Al-
MCM-41 or Al-SBA-15) in doubly distilled water (100 mL), and the
mixture was stirred for 48 h at 608C. The solid was separated by
centrifugation and washed with doubly distilled water until free of
chlorine. Then it was dried at 958C for 90 min, calcined at 3508C
À1
for 12 h with a heating rate of 18Cmin , and reduced under
À1
a flow of hydrogen (30 mLmin ) at 4508C for 6 h.
Catalytic tests
The catalytic tests were performed in batch experiments under stir-
ring conditions by using a Teflon-lined autoclave (16 mL) from HEL
starting with 0.1 mg Pt (in Pt(0.5 wt%)-Al-MCM-41 or Pt(0.5 wt%)-
Al-SBA-15 catalyst) and a substrate/Pt molar ratio of 20:1 dispersed
in heptane (5.0 mL). The reactions were performed at 1008C under
Catalyst characterization
N adsorption–desorption isotherms were recorded at À1968C by
2
using a Micromeritics ASAP2020 automated instrument. Before
analysis, the catalysts pretreated under H at 4008C were firstly ex-
2
a pressure of 30 bar H , and reaction times in the range of 1.5–12 h
2
posed to Ar and then degassed for 15 h at 1508C and 1.3”
were used. The autoclave was charged in a N -filled dry box with
2
À9
1
0
atm. The surface areas were estimated according to the BET
the catalyst and then flushed several times with H before pressuri-
2
model, and the pore size dimensions were calculated using the
Barrett–Joyner–Halenda (BJH) method. Powder XRD patterns were
zation. The reactants and products were analyzed by GC–MS by
using a TraceGOLD-5SilMS 2000 column coupled with DSQ MS
from Thermo Electron Corporation. The hydrogenation pathways
of the products are described in detail in Tables 4 and 5. The struc-
tures of the resulting products were confirmed by H and C NMR
spectroscopy by using a Bruker Avance Ultrashield 500 spectrome-
ter in DMSO solvent with TMS as the internal standard.
recorded by using a Phillips PW 1830 diffractometer using CuK ra-
a
diation. Patterns were collected in steps of 2q=0.028 over the an-
gular ranges 2q=1–20 or 10–808 for 25 s per step.
1
13
H -pulse chemisorption measurements were performed by using
2
an ASAP AutoChemII 2920 station from Micromeritics. Prereduced
catalysts (~20 mg) were introduced into a U-shaped quartz reactor
with an inner diameter of 0.5 cm, heated under He at 2008C,
A TRACETM Ultra Gas Chromatograph fitted with a TraceGOLD
column was used. The data were acquired and processed using
Thermo Scientific Xcalibur data handling software.
À1
cooled to RT under a He flow of 50 mLmin , and then exposed to
pulses of H at RT until surface saturation. To determine the irrever-
2
The content and leaching of Pt was checked by inductively cou-
pled plasma optical emission spectroscopy (ICP-OES; Agilent Tech-
nologies, 700 Series) after the instrument was calibrated with stan-
dard solutions. Carbon elemental analysis was performed by using
a EuroEA 3000 automated analyzer. The sample (less than 1 mg)
was weighed into a tin container and burned in a vertical reactor
(oxidation tube) in the dynamic mode at 9808C in an He flow with
sibly adsorbed hydrogen, the samples were then heated under He
at 608C. The hydrogen consumption to form the monolayer was
calculated by extrapolating the linear portion of the adsorption iso-
therm to zero pressure. The number of exposed metal atoms was
calculated by assuming an atomic stoichiometry H/Pt=1:1. The
average metal particle size was estimated by assuming a spherical
[40]
particle model.
Subsequently, H -TPD experiments were per-
2
the addition of O (10 mL) at the instant of sample introduction.
2
formed by using the same instrument once saturation was reached
À1
Portions of the sample in tin capsules were placed in the automat-
ed sampler and were transferred to the oxidation tube at regular
intervals. The concentration of carbon was calculated using the
Callidus program supplied with the analyzer.
at a heating rate of 58Cmin up to 3508C. The amount of H2
evolved in the gas phase was quantified using a calibration curve.
Py-FTIR spectra were recorded by using a Thermo Electron Nicolet
À1
4
700 FTIR spectrometer with a resolution of 4 cm . Before the ad-
sorption of the base, the powder samples were calcined at 4508C
À1
for 2 h under an air flow of 30 mLmin . Self-supporting wafers ob-
À2
Acknowledgements
tained by compression (ꢀ12 mgcm ) were outgassed in the IR
cell at 4008C at a residual pressure of 1 atm. After the adsorption
of the probe, the samples were purged for 2 h with He at RT to
remove the weakly sorbed species and then heated to each meas-
uring temperature.
We thank the Ministry of Education, Science and Sport of the Re-
public of Slovenia and the Slovenian Research Agency for finan-
cial support (P1-0230-0103). This work was also partially support-
ed within the infrastructure of EN, FIST Center of Excellence,
Ljubljana, and by the Vietnam National Foundation for Science
and Technology Development (NAFOSTED) under the grant
number 104.05-2014.21. I.C.B, C.R., and V.I.P are grateful for fi-
nancial support from UEFISCDI, project 151/2012 code PN-II-PT-
PCCA-2011-3.2-0731.
TEM was performed by using a JEOL JEM-1010 microscope with an
accelerating voltage of 100 kV. Samples were prepared by powder
dispersion in ethanol and subsequent deposition on a gold grid
with a carbon support.
XPS spectra of both fresh and used catalysts were recorded at RT
by using a SSX-100 spectrometer, Model 206 from Surface Science
Instrument. To limit reoxidation, the reduced samples were trans-
ferred from the reduction setup to the Raman and XPS apparatus
Keywords: aluminum
materials · platinum · supported catalysts
·
hydrogenation
·
mesoporous
[41]
under isooctane. The pressure in the analysis chamber during
the analysis was 1.33 MPa. Monochromatized AlK radiation (hn=
a
1
486.6 eV) generated by bombarding the Al anode with an elec-
tron gun operated at a beam current of 12 mA and acceleration
voltage of 10 kV was used. The spectrometer energy scale was cali-
brated using the Au4f7/2 peak centered at BE=83.98 eV. Charge
[
1] a) V. A. Gembicki, T. M. Cowan, G. R. Brierley, Hydrocarbon Process. 2007,
86, 41–53; b) A. R. Beltramone, D. E. Resasco, W. E. Alvarez, T. V.
Choudhary, Ind. Eng. Chem. Res. 2008, 47, 7161–7166.
ChemCatChem 2016, 8, 1146 – 1156
www.chemcatchem.org
1155
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers
[
2] V. I. Parvulescu, P. Granger in Perovskites and Related Mixed Oxides: Con-
cepts and Applications, 1st ed. (Eds.: P. Granger, V. I. Parvulescu, S. Kalia-
guine, W. Prellier), Wiley-VCH, Weinheim, 2016, pp. 415–438.
3] S. Jongpatiwut, Z. Li, D. E. Resasco, W. E. Alvarez, E. L. Sughrue, G. W.
Dodwell, Appl. Catal. A 2004, 262, 241–253.
[22] M. Kolobielski, J. Org. Chem. 1963, 28, 1883–1885.
[23] W. E. Bachmann, M. C. Kloetzel, J. Am. Chem. Soc. 1938, 60, 481–485.
[24] a) W. Ried, H. Schinzel, Liebigs Ann. Chem. 1982, 1569–1572; b) G.
Díaz de Delgado, B. Ramírez, W. Velµsquez, P. Rodríguez, Acta Crystal-
logr. Sect. E 2002, 58, o501–o503.
[25] W. Kitching, W. Adcock, T. C. Khor, D. Doddrell, J. Org. Chem. 1976, 41,
2055–2058.
[
[
4] S. C. Korre, M. T. Klein, R. J. Quann, Ind. Eng. Chem. Res. 1995, 34, 101–
117.
[
[
[
5] V. Y. Davydov, N. Sheppard, E. Osawa, J. Catal. 2002, 211, 42–52.
6] C. Morin, D. Simon, P. Sautet, J. Phys. Chem. B 2004, 108, 12084–12091.
7] W. H. Wiser, S. Singh, S. A. Qader, G. R. Hill, Ind. Eng. Chem. Prod. Res.
Dev. 1970, 9, 350–356.
[26] J. S. Meek, B. T. Poon, S. J. Cristol, J. Am. Chem. Soc. 1952, 74, 761–763.
[27] B. Kuran, M. Krawiecka, J. Kossakowski, M. Koronkiewicz, Z. Chilmonc-
zyk, Acta Pol. Pharm. 2013, 70, 459–468.
[28] J. S. Beck, J. C. Vartuli, W. J. Roth, M. E. Leonowicz, C. T. Kresge, K. D.
Schmitt, C. T. W. Chu, D. H. Olson, E. W. Sheppard, E. W. McMullen, J. B.
Higgins, J. L. Schlenker, J. Am. Chem. Soc. 1992, 114, 10834–10843.
[29] J. lvarez-Rodríguez, I. Rodríguez-Ramos, A. Guerrero-Ruiz, A. Arcoya,
Appl. Catal. A 2011, 401, 56–64.
[
[
8] J. L. Pinilla, H. Puron, D. Torres, I. Suelves, M. Millan, Carbon 2015, 81,
5
74–586.
9] A. F. Borowski, L. Vendier, S. Sabo-Etienne, E. Rozycka-Sokolowska, A. V.
Gaudyn, Dalton Trans. 2012, 41, 14117–14125.
[
[
10] S. Yang, L. M. Stock, Energy Fuels 1996, 10, 1181–1186.
11] L.-B. Sun, X.-Y. Wei, X.-Q. Liu, Z.-M. Zong, W. Li, J.-H. Kou, Energy Fuels
[30] C. Opris, B. Cojocaru, N. Gheorghe, C. Teodorescu, M. Tudorache, S. M.
Coman, L. Tanase, V. I. Parvulescu, B. Duraki, F. Krumeich, J. A. van Bok-
hoven, unpublished results.
2009, 23, 4877–4882.
[
[
12] a) Z.-G. Zhang, K. Okada, M. Yamamoto, T. Yoshida, Catal. Today 1998,
[31] V. Pârvulescu, S. Coman, V. I. Parvulescu, P. Grange, G. Poncelet, J. Catal.
1998, 180, 66–84.
[32] N. Echoufi, P. Gelin, Catal. Lett. 1996, 40, 249–252.
[33] a) H. Pulm, G. Hohlneicher, H.-J. Freund, J. Less-Common Met. 1986, 115,
127–143; b) J. Thiele, N. T. Barrett, R. Belkhou, C. Guillot, H. Koundi, J.
Phys. Condens. Matter 1994, 6, 5025–5038.
[34] S. Seal, S. Krezoski, T. L. Barr, D. H. Petering, J. Klinowski, P. H. Evans,
Proc. R. Soc. London Ser. B 1996, 263, 943–951.
[35] C. D. Wagner, D. E. Passoja, H. F. Hillery, T. G. Kinisky, H. A. Six, W. T.
Jansen, J. A. Taylor, J. Vac. Sci. Technol. 1982, 21, 933–944.
[36] F. P. J. Kerkhof, J. A. Moulijn, A. Heeres, J. Electron Spectrosc. Relat.
Phenom. 1978, 14, 453–466.
[37] Y. Xu, X. Wei, Y. Shi, Y. Zhang, X. Guo, J. Mol. Catal. 1986, 36, 79–89.
[38] a) A. M. Venezia, R. Bertoncello, G. Deganello, Surf. Interface Anal. 1995,
23, 239–247; b) W. A. M. Aarnink, A. Weishaupt, A. van Silfout, Appl.
Surf. Sci. 1990, 45, 37–48.
4
5, 361–366; b) Z.-G. Zhang, T. Yoshida, Energy Fuels 2001, 15, 708–
7
13.
13] a) J.-P. Deng, W.-C. Shih, C.-Y. Mou, ChemPhysChem 2005, 6, 2021–2025;
b) J.-P. Deng, W.-C. Shih, C.-Y. Mou, J. Phys. Chem. C 2007, 111, 9723–
9
728.
14] X. Wang, L. Andrews, L. Manceron, C. Marsden, J. Phys. Chem. A 2003,
07, 8492–8505.
15] K. H. Park, K. Jang, H. J. Kim, S. U. Son, Angew. Chem. Int. Ed. 2007, 46,
152–1155; Angew. Chem. 2007, 119, 1170–1173.
[
[
[
[
[
1
1
16] M. J. Jacinto, O. H. C. F. Santos, R. Landers, P. K. Kiyohara, L. M. Rossi,
Appl. Catal. B 2009, 90, 688–692.
17] J. L. Pinilla, A. B. García, K. Philippot, P. Lara, E. J. García-Suµrez, M.
Millan, Fuel 2014, 116, 729–735.
18] W. Liao, H.-W. Liu, H.-J. Chen, W.-Y. Chang, K.-H. Chiu, C. M. Wai, Chemo-
sphere 2011, 82, 573–580.
[
[
[
19] T. Yuan, W. D. Marshall, J. Hazard. Mater. 2005, 126, 149–157.
20] O. Diels, W. E. Thiele, Chem. Ber. 1938, 71B, 1173–1178.
21] a) S. Sankararaman, Pericyclic Reactions—A Textbook: Reactions, Applica-
tions and Theory, Wiley-VCH, Weinheim, 2005; b) M. B. Smith, March’s
Advanced Organic Chemistry: Reactions, Mechanisms, and Structure,
[39] R. L. Smith, P. A. Naro, A. J. Silvestri, J. Catal. 1971, 20, 359–366.
[40] E. Berner, U. Kjennerud, Acta Chem. Scand. 1963, 17, 2669–2673.
[41] https://www.chemeo.com/cid/37-245-9/Anthracene.
7
th ed., Wiley, Hoboken, 2013; c) J.-A. Funel, S. Abele, Angew. Chem. Int.
Ed. 2013, 52, 3822–3863; Angew. Chem. 2013, 125, 3912–3955; d) M.
Krivec, K. Kranjc, S. Polanc, M. Ko cˇ evar, Curr. Org. Chem. 2014, 18, 1520–
Received: November 24, 2015
1
527.
Published online on February 10, 2016
ChemCatChem 2016, 8, 1146 – 1156
www.chemcatchem.org
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ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim