Catalytic Methylation of Aromatic Hydrocarbons using CO2/H2 over Re/TiO2 and H-MOR Catalysts

Article abstract of DOI:10.1002/cctc.202000036

A combined catalyst comprising TiO₂-supported Re (Re(1)/TiO₂; Re=1 wt%) and H-MOR (SiO₂/Al₂O₃=90) was found to promote the methylation of benzene using CO₂ and H₂. This catalytic system exhibited high performance with regard to the synthesis of methylated benzenes and gave high yields of total methylated products (up to 52 % benzene-based yield and 42 % CO₂-based yield) under the reaction conditions employed in this study (p_CO2=1 MPa; p_H2=5 MPa; T=250 °C; t=20 h) in a batch reactor. Catalyst screening demonstrated that a combination of Re(1)/TiO₂ and H-MOR (SiO₂/Al₂O₃=90) exhibited superior performance compared to other combinations of supported metal catalysts and zeolites in terms of both yield and selectivity for methylated benzenes.

Full text of DOI:10.1002/cctc.202000036

Accepted Article
Title: Catalytic Methylation of Aromatic Hydrocarbons using CO2/H2
over Re/TiO2 and H-MOR catalysts
Authors: Kah Wei Ting, Haruka Kamakura, Sharmin Poly, Takashi
Toyao, S. M. A. Hakim Siddiki, Zen Maeno, Koichi Matsushita,
and Ken-ichi Shimizu
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: ChemCatChem 10.1002/cctc.202000036
Link to VoR: http://dx.doi.org/10.1002/cctc.202000036
A Journal of
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ChemCatChem
10.1002/cctc.202000036
COMMUNICATION
Catalytic Methylation of Aromatic Hydrocarbons using CO
2
/H
2
over Re/TiO
2
and H-MOR catalysts
Kah Wei Ting, Haruka Kamakura, Sharmin S. Poly, Takashi Toyao,* S. M. A. Hakim Siddiki,[a]
[
a]
[a]
[a]
[a,b]
[
a]
[c]
[a,b]
Zen Maeno, Koichi Matsushita, Ken-ichi Shimizu,*
Abstract: A combined catalyst comprising TiO
Re(1)/TiO ; Re = 1 wt%) and H-MOR (SiO /Al
found to promote the methylation of benzene using CO
This catalytic system exhibited high performance with regard to
the synthesis of methylated benzenes and gave high yields of
total methylated products (up to 52% benzene-based yield and
2
-supported Re
= 90) was
and H
C-methylation to form aromatic C–H bonds using CO
2
/H
2
to
(
2
2
2
O
3
replace MeOH as the CH
3
source.[18] Their work involved the use
2
2
.
of Ru-based homogeneous catalytic systems to promote the C-
methylation of electron-rich arenes. However, although this prior
work was highly seminal and impactful, the reported substrate
scope was limited solely to electron-rich arenes with high
reactivities. It would be highly desirable to also perform the C-
methylation of unactivated aromatic hydrocarbons such as
benzene to generate new aromatic compounds. Currently, C-
methylation in the petroleum industry is performed using MeOH
together with disproportionation/transmethylation over zeolite
catalysts to produce methylated aromatic hydrocarbons such as
p-xylene, which is widely used as a precursor for plastics.[19] It is
therefore anticipated that a combination of MeOH-producing
catalysts and methylation catalysts such as zeolites could afford
4
2
2% CO -based yield) under the reaction conditions employed in
this study (pCO2 = 1 MPa; pH2 = 5 MPa; T = 250 °C; t = 20 h) in a
batch reactor. Catalyst screening demonstrated that
combination of Re(1)/TiO and H-MOR (SiO /Al
a
2
2
2
O
3
=
90)
exhibited superior performance compared to other combinations
of supported metal catalysts and zeolites in terms of both yield
and selectivity for methylated benzenes.
The utilization of carbon dioxide (CO
gas as a C source has been the subject of intensive research
over the past several decades. The use of CO as a chemical
feedstock could be a means of reducing atmospheric CO
concentrations, and CO is also abundant, nontoxic and readily
available.[1–5] There is thus significant interest in the catalytic
transformation of CO via hydrogenation to produce chemicals,
especially methanol (MeOH), because this is an important
commodity chemical that serves as a versatile C building block
in chemical synthesis.[6] Although the direct production of MeOH
from the hydrogenation of CO has recently been achieved
2
), an important greenhouse
the one-pot synthesis of methylated benzenes from benzene, CO
and H
In the present study, a combined system consisting of a
-supported Re catalyst (Re(1)/TiO ; Re loading = 1 wt%) that
exhibits high catalytic performance for low temperature MeOH
synthesis[12] and the zeolite H-MOR (SiO
/Al = 90) was
employed for the direct methylation of benzene using CO and H
2
,
1
2
.
2
2
TiO
2
2
2
2
2 3
O
2
2
2
(pCO2 = 1 MPa; pH2 = 5 MPa; T = 250 °C). Catalyst screening using
various combinations of supported metal catalysts and zeolites
having a wide range of SiO /Al O ratios showed that this
2 2 3
1
2
industrially using Cu-based catalysts under relatively harsh
combination provided the best performance for the methylation
conditions (T > 200 °C; p = 5-10 MPa),[7] this process suffers from
reaction. Although the methylation of arenes, including benzene,
using syngas (that is, CO/H
use of CO
synthesis of aromatic hydrocarbons, including methylated
benzenes, from CO /H mixtures that do not already contain
2
) has been reported,[
20–23]
the direct
a low equilibrium conversion of CO
limitation.[
2
due to thermodynamic
8,9]
2
would be beneficial. In addition, while the direct
One possible approach to achieve high CO
2
conversion is
use of a lower reaction temperature to produce MeOH.[
However, the development of a catalyst for low temperature
MeOH synthesis is a formidable task. Another popular strategy to
address this issue associated with the thermodynamic limitation
10–12]
2
2
benzene has been realized, these processes typically require
harsh conditions.[24–30] In contrast, our process provides an
effective means of upgrading crude oils and should also
is to employ a CO
2
/H
2
mixture as the methylation reagent instead
contribute to decreasing the total CO
petroleum refining processes.
2
emissions produced during
of MeOH for the one-pot synthesis of value-added chemicals (see
Figure S1 for representative equilibrium calculations).[13] In
particular, N-methylation through the formation of C–N bonds for
the synthesis of various methylamines has been widely
explored.[14–17] Moreover, in 2014, Beller and coworkers reported
Re(1)/TiO
2
was synthesized using simple wet
a
impregnation method, employing NH
4
ReO and TiO (Refer to the
4
2
Supporting Information for a more detailed procedure). Scanning
transmission electron microscopy (STEM) images of the
2
Re(1)/TiO (Figure S2) confirmed that the Re was loaded on the
TiO
2
support in the form of highly dispersed sub-nanometer
[
a]
K. W. Ting, H. Kamakura, Dr. Sharmin S. Poly, Dr. T. Toyao, Dr. S.
M. A. H. Siddiki, Dr. Z. Maeno, Prof. Dr. K. Shimizu,
Institute for Catalysis, Hokkaido University, N-21, W-10, Sapporo
[31]
clusters. Commercially-available zeolite catalysts were used as
received. For each catalytic reaction, the active catalyst was
prepared by physically mixing both materials with subsequent
001-0021 (Japan)
E-mail: toyao@cat.hokudai.ac.jp, kshimizu@cat.hokudai.ac.jp
Dr. T. Toyao, Prof. Dr. K. Shimizu
Elements Strategy Initiative for Catalysis and Batteries, Kyoto
University, Katsura, Kyoto 615-8520 (Japan)
Dr. K. Matsushita
reduction in a quartz tube (T = 500 °C; t = 0.5 h) under a flow of
[
b]
c]
-1
H
2
(20 mL min ).
In the initial phase of this study, the methylation of benzene
using CO /H was carried out to assess the properties of various
2 2
[
Central Technical Research Lab, JXTG Nippon Oil & Energy
Corporation, Yokohama, Kanagawa 231-0815 (Japan).
MeOH synthesis catalysts, and the results are summarized in
Figure 1 (Full data for the catalyst screening are provided in
Supporting information for this article is given via a link at the end of
the document.
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ChemCatChem
10.1002/cctc.202000036
COMMUNICATION
systems. Subsequently,
the performances of
various supported Re
6
5
4
3
2
1
0
0
0
0
0
0
0
40
(A)
catalysts
were
also
3
0
evaluated (Figure 1A),
and the product yields
were
found
to
be
20
significantly lower than
that
obtained
with
Re(1)/TiO
2
. The industrial
MeOH synthesis catalyst
Cu/ZnO/Al (MDC-7;
4 wt% Cu) was also
1
0
0
2
O
3
3
examined and found to
be ineffective under the
reaction
conditions
employed in this study.
These results suggested
that Re(1)/TiO
the best MeOH synthesis
component for this
methylation process.
After establishing
-supported Re
2
would be
M/TiO2
Hydrogenation catalyst
Re/Support
20
60
50
40
30
20
10
0
Toluene
o-xylene
m-xylene
TiO
2
(B)
catalyst as the MeOH
synthesis catalyst, we
p-xylene
Ethylbenzene
C *
proceeded
screening
to
the
zeolite
of
catalysts having various
distinctive framework
9+
10
Dearomatized products
Diphenylmethane
CO
types with a wide
range of SiO
2
2 3
/Al O
ratios for the methylation
of benzene using CO /H
(Figure 1B). H-MOR was
CH4
2
2
Alkanes (C -C )
2
4
MeOH
found
favorable
to be more
for the
0
formation of toluene and
p-xylene when compared
to other zeolite catalysts
tested in this study.
Comparisons of various
H-MOR (SiO
2 2 3
/Al O = 20,
Methylation catalyst
9
0 and 220) showed that
H-MOR(90) (Bracketed
number denotes the
Figure 1. Screening of (A) hydrogenation catalysts (M/TiO
methylation of benzene using CO and H . Pre-treatment: 500 °C, 0.5 h under a H
conditions: 1 wt% of supported metal catalyst (mass adjusted to contain 0.0081 mmol of loaded metal per
2
and Re/Support), and (B) zeolite catalysts for the
-
1
2
2
2
flow (20 mL min ); reaction
SiO
2
/Al
2
O
3
ratio
for
zeolites) gave the highest
experiment) with 0.10 g of zeolite catalyst, 1.0 mmol of benzene, CO
2
(1 MPa), H
yield.
9
-based yield is shown in right axis. *Includes C to C12 methylated
2
(5 MPa), 250 °C, 20 h. Benzene-
However,
MOR(220) gave a higher
product formation rate
H-
based yield is shown in left axis whereas CO
benzenes.
2
calculated based on the number of protonic sites (Figure 2). This
could be attributed to the fact that increasing SiO /Al ratio
enhances the hydrophobic reaction between the zeolite pores and
the substrate, which in this case, benzene, thus leading to a
higher product formation rate when adjusted to the number of
protonic sites.[32]
Table S1). First, the catalytic performances of various supported
metal catalysts were compared and evaluated.
A combination of Re(1)/TiO and H-MOR(90) afforded the highest
2
yield of methylated products (52% benzene-based yield). It
should be noted here that undesired dearomatized products were
not observed for this catalytic system. In contrast, not only did
2
2 3
O
2
other TiO -supported metal catalysts (Figure 1A) afforded
relatively low total product yields, dearomatized products such as
cyclohexane and methylcyclohexane were also detected in those
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ChemCatChem
10.1002/cctc.202000036
COMMUNICATION
0
.2
.1
0
4
3
2
1
0
attempted using either Re(1)/TiO
2
or H-MOR(90) individually. In
both cases, the reaction barely proceeded with little to no
methylated products detected. The reaction was also carried out
using Re(1)/H-MOR(90), but the performance was far inferior to
that obtained from the combination of Re(1)/TiO
These results suggest that the presence of both Re(1)/TiO
H-MOR(90) is crucial to obtaining a high degree of catalytic
performance from this methylation process. The effect of reaction
temperature on the methylation of benzene was also investigated
Toluene
o-xylene
m-xylene
p-xylene
2
and H-MOR(90).
and
2
Ethylbenzene
C9+
*
0
Diphenylmethane
(
Figure S4). 250 °C was chosen as the optimal temperature for
our system considering the higher relative yield of main products
when compared to the yield of unwanted by-products.
Next, we proceeded to carry out the methylation of benzene
employing Re(x)/TiO
determine the optimal Re loading (Figure 3A) for the reaction
Refer to Figure S3 for the STEM images of Re(x)/TiO ). The
highest yields of toluene and p-xylene were obtained using
Re(1)/TiO . This outcome can be attributed to the fact that this
2
(x = 0.2, 0.5, 1, 5, 10 or 20 wt%) to
(
2
2
0
90
220
2
SiO /Al O ratio
material gave the highest MeOH formation rate, as reported in our
previous work.[31] The product selectivity appeared to shift
2
2
3
Figure 2. Effect of the SiO
using CO and H catalyzed by Re(1)/TiO
treatment: 500 °C, 0.5 h under a H flow (20 mL min ); reaction
conditions: 0.0081 mmol of loaded metal with 0.10 g of the zeolite,
.0 mmol of benzene, CO (1 MPa), H (5 MPa), 250 °C, 1 h.
Includes C to C12 methylated benzenes.
2
/Al
O
2 3
ratio on the methylation of benzene
gradually towards CH
4
with increasing Re loading. This was not
2
2
2
and H-MOR. Pre-
unexpected, since larger clusters of Re species are known to
-
1
2
[
31]
enhance the formation of CH
found to decrease gradually as the Re loading was increased.
Re/TiO with a lower Re loading (< 1 wt%) may have a higher
4
.
The total product yield was also
1
2
2
2
*
9
fraction of isolated atomic Re species, which has been shown to
favor the formation of CO. The dearomatization of benzene was
observed when using Re(x)/TiO with higher Re loadings (> 1
2
wt%). These results indicate that dearomatization was caused by
aggregated Re species that appear predominantly at loadings
H-ZSM-5, which is widely used for the alkylation of benzene
due to its high activity and selectivity,[33,34] was found to be less
effective for the formation of toluene and xylenes as compared to
H-MOR in this study. Although yields of methylated products are
low, it is worth mentioning that a relatively large amount of light
above 1 wt%. Based on these data, Re(1)/TiO
2
was found to be
the most suitable catalyst for this reaction.
2 4
alkanes (C -C
), which are considered as valuable products[35,36]
The effect of the pre-treatment temperature on the
methylation of benzene using CO and H was also investigated,
employing the optimized reaction conditions (Figure 3B). H
were detected when H-CHA zeolite was used. Based on these
results, H-MOR(90) was identified to be the most suitable
methylation catalyst for the present combined catalyst system. A
series of control experiments were also performed without CO
or benzene, and no major products were detected following
these reactions (Table S1). In place of a mixture of Re(1)/TiO
and H-MOR(90), the catalytic methylation of benzene was also
2
2
2
reduction at 500 °C gave the best performance in terms of both
total methylation yield and product selectivity, while higher yields
of CO were observed at lower temperatures (no reduction and T
2
,
H
2
2
=
200 or 300 °C). This result is partly ascribed to the higher
6
5
4
3
2
1
0
0
0
0
0
0
0
40
60
50
40
30
20
10
0
40
30
20
10
0
(
A)
(B)
3
0
20
1
0
0
0
.2
0.5
Re loading [wt%]
Figure 3. Effects of (A) Re loading and (B) reduction pre-treatment temperature on the product distribution for the methylation of benzene using
1
5
10
20
No red. 200
300
500
700
900
Reduction temperature [˚C]
-
1
CO
MOR(90), 1.0 mmol of benzene, CO
is shown in right axis. *Includes C
2
and H
2
. Pre-treatment: 500 °C, 0.5 h under a H
2
flow (20 mL min ); reaction conditions: 0.0081 mmol of loaded Re with 0.10 g of H-
-based yield
2
(1 MPa), H (5 MPa), 250 °C, 20 h. Benzene-based yield is shown in left axis whereas CO
2
2
9
to C12 methylated benzenes. The same legend is used as in Figure 1.
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ChemCatChem
10.1002/cctc.202000036
COMMUNICATION
proportion of isolated Re atoms on the less reduced specimens,
which tend to promote the formation of CO.
one-pot methylation reaction using CO
2
/H
2
can achieve higher
-to-methanol
CO conversion in one pass compared to direct CO
2
2
A plot showing the time course of benzene methylation is
presented in Figure 4. The product concentrations are seen to
increase gradually as the reaction proceeds. The decrease in the
rate of increase of the toluene yield approaching t = 20 h is
possibly due to further methylation of toluene to form multi-
methylated benzenes, as shown by the data at a reaction time of
reaction. Recycling tests for our catalyst system were also
attempted, and the results are shown in the supporting
information (Figure S5).
2
Re(1)/TiO + H-MOR(90)
a)
+ CO
2
+
H
2
+ xylenes + C9+
*
+
+
250 ˚C, 1 h
1
mmol 1 MPa 5 MPa
9.2
0.1
1.9 1.3
0.9
3
0 h.
4
0
0
0
0
0
+
CO
(32.0)
+
MeOH
(<0.1)
Formation rate
=
Re(1)/TiO
2
+ H-MOR(90)
b)
+
MeOH
8 mmol
+
xylenes +
1.2
C
9+*+
+
N
2
1MPa, 250 ˚C, 1 h
3
2
1
1 mmol
7.8
1.8
0.1
Toluene
o-xylene
m-xylene
p-xylene
C *
+
CO
+
CO
2
<
0.1
(5.5)
(51.2)
Re(1)/TiO
2
+ H-MOR(90)
c)
+ CO
+
H
2
+
xylenes + C9+* +
+
250 ˚C, 1 h
9+
1
mmol 1 MPa 5 MPa
3.0
0.4
0.5
<0.1
Ethylbenzene
Diphenylmethane
+
CO
2
+
MeOH
(<0.1)
0.3
(31.8)
Re(1)/TiO
2
+ H-MOR(90)
d)
+
HCOOH
8 mmol
+
H
2
+
xylenes + C9+* +
+
250 ˚C, 1 h
1
mmol
5 MPa
2.0
0.7
0.7
0.4
0
5
10
Reaction time [h]
Figure 4. Time course plot for the methylation of benzene using CO
and H catalyzed by Re(1)/TiO and H-MOR(90). Pre-treatment:
00 °C, 0.5 h under a H flow (20 mL min ); reaction conditions: 0.15
g of Re(1)/TiO and 0.10 g of H-MOR (SiO /Al = 90), 1.0 mmol of
benzene, CO (1 MPa), H (5 MPa), 250 °C.
15
20
25
30
+
CO
+
CO
2
+
MeOH
(3.3)
0.1
(247.0)
(498.4)
2
2
2
Unit = ×10-2 mmol·h-1
-
1
5
2
2
Scheme 1. Methylation of benzene catalyzed by Re(1)/TiO and H-
2
2
2 3
O
MOR (SiO
2
/Al
2
O
3
= 90) using a) CO
2
, b) MeOH, c) CO and d) HCOOH
to C12 methylated benzenes.
2
2
as methylating agents. *Includes C
9
To gain more insights into the specifics of the reaction,
methylation reactions employing various methylating agents,
including MeOH, HCOOH and CO, were carried out under the
comparable reaction conditions (Scheme 1). Note that each
reaction was performed for just 1 h so as to observe the initial
2
reaction rates. Both CO/H and HCOOH (Scheme 1, c & d) were
found to be ineffective when applied to this reaction and led to
lower formation rates of overall methylated products compared to
the reaction with CO
reaction proceeded efficiently when MeOH was used even in the
absence of CO and H , suggesting that MeOH is a possible
intermediate in this reaction system (Scheme 1, b). It is likely that
MeOH is first produced from CO /H over the Re(1)/TiO and that
2 2
/H (Scheme 1, a). On the other hand, the
2
2
2
2
2
subsequent methylation reactions take place between this MeOH
and benzene over the H-MOR(90).
Lastly, the methylation reaction was performed by using
higher amount of benzene than in the standard reaction condition.
2
The CO -based yield for methylated products was 9% under
standard reaction condition (1 mmol of benzene). The yields
increased significantly to 32% and 42% when 10 mmol and 20
mmol of benzene was used, respectively (Figure 5), even
2
surpassing the theoretical one-pass yield for CO -to-methanol
reaction at 250 °C (theoretical methanol yield = 30%; see Figure
S1 for the equilibrium calculation). The results clearly proved that
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ChemCatChem
10.1002/cctc.202000036
COMMUNICATION
6
5
4
3
2
1
0
0
0
0
0
0
0
60
50
40
30
20
10
0
1
2
0
8
6
4
2
0
1
α-MN*
β-MN*
,6-DMN*
2
DMNs* (excluding 2,6-DMN)
Tetralin
1
10
Amount of benzene [mmol]
Figure 5. Methylation of benzene using CO and H
Re(1)/TiO
reactant. Pre-treatment: 500 °C, 0.5 h under a H
reaction conditions: 0.15 g of Re(1)/TiO and 0.10 g of H-MOR
SiO /Al = 90), CO (1 MPa), H (5 MPa), 250 °C, 20 h. Benzene-
based yield is shown in left axis whereas CO -based yield is shown in
right axis. *Includes C to C12 methylated benzenes. The same legend
is used as in Figure 1.
20
0
10
20
30
Reaction time [h]
2
2
catalyzed by
Figure 6. Time course plot for the methylation of naphthalene using
2
and H-MOR(90) with different initial amount of benzene as
CO
500 °C, 0.5 h under a H
g of Re(1)/TiO
2
and H
2
catalyzed by Re(1)/TiO
2
and H-BEA(40). Pre-treatment:
-
1
-1
2
flow (20 mL min );
2
flow (20 mL min ); reaction conditions: 0.15
2
2
and 0.10 g of H-BEA(40), CO
2
(1 MPa), H
2
(5 MPa),
(
2
2
O
3
2
2
230 °C. *MN = Methylnaphthalene, DMN = Dimethylnaphthalene.
2
In conclusion, one-pot synthesis of value-added products
9
using a mixture of CO
combination of CO
We developed
2 2
/H was demonstrated by employing a
2
hydrogenation catalyst and zeolite catalyst.
a heterogeneous catalytic system for the
The catalytic methylation of naphthalene using CO
was also carried out to explore the applicability of our catalyst
system. Instead of Re(1)/TiO and H-MOR(90), which were
identified to be the best catalysts for the methylation of benzene,
the combination of Re(1)/TiO and H-BEA(40) was found to be the
2
and H
2
methylation of benzene using CO
2
and H
2
. After a thorough
and H-
2
catalyst screening process, the combination of Re(1)/TiO
2
MOR(90) was found to promote the reaction to give a high yield
of methylated products at a reaction temperature of 250 °C. The
2
most effective in the case of naphthalene, giving the highest yield
of total methylated products (up to 26% naphthalene-based yield).
More detailed results can be found in Supporting Information
catalytic methylation of naphthalene using CO
carried out successfully using similar catalyst system
comprising Re(1)/TiO and H-BEA(40), with reaction
temperature of 230 °C. A series of control experiments showed
2 2
and H was also
a
2
a
(
Table S2). The catalytic methylation of naphthalene using CO
2
and H was performed at 230 °C rather than 250 °C as the higher
2
that the reaction proceeds via a MeOH pathway, with CO
source of the methyl group.
2
as the
temperature promoted the formation of unwanted by-products
such as tetralin. The time course plot for the methylation of
naphthalene is shown in Figure 6.
Acknowledgements
This study was supported financially by NEDO (New Energy and
Industrial Technology Development Organization) and by
KAKENHI grants (18K14057, 18K14051 and 17H01341) from
JSPS, by MEXT as part of the Elements Strategy Initiative to Form
Core Research Center project (JPMXP0112101003), and by JST-
CREST (JPMJCR17J3), as well as by IRCCS. The authors are
also grateful to the technical staff at the Institute for Catalysis at
Hokkaido University for preparing the experimental setup and
wish to thank the staff at the Open Facility of Hokkaido University
for their assistance with STEM observations.
2
Keywords: CO hydrogenation • C-methylation • Aromatics • One-
pot synthesis
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ChemCatChem
10.1002/cctc.202000036
COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
The catalytic methylation of benzene
Kah Wei Ting, Haruka Kamakura,
Sharmin S. Poly, Takashi Toyao,* S.
M. A. Hakim Siddiki, Zen Maeno,
Koichi Matsushita, Ken-ichi Shimizu,*
using CO
conjunction with a catalyst system
comprising TiO -supported Re
Re(1)/TiO ) and H-MOR (SiO
90). This catalyst combination gave
2 2
and H was performed in
2
(
2
2 2 3
/Al O
Page No. – Page No.
=
high yields and selectivity for
methylated benzene compounds.
Catalytic Methylation of Aromatic
Hydrocarbons using CO
2 2
/H over
The
catalytic
methylation
of
Re/TiO and H-MOR catalysts
2
naphthalene was also successfully
carried out using a similar catalytic
system consisting of Re(1)/TiO
H-BEA (SiO /Al = 40).
2
and
2
2 3
O
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