Nonoxidative conversion of methane and n-pentane over a platinum/alumina catalyst

Article abstract of DOI:10.1134/S0023158416040042

Methane adsorption on the Pt–H/Al₂O₃ and Pt/Al₂O₃ catalysts begins at Т = 475°C and is accompanied by the appearance of hydrogen in the reaction medium. At a higher temperature is raised to 550°C, the amount of

Full text of DOI:10.1134/S0023158416040042

ISSN 0023-1584, Kinetics and Catalysis, 2016, Vol. 57, No. 4, pp. 504–510. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © D.V. Golinskii, N.V. Vinichenko, V.V. Pashkov, I.E. Udras, O.V. Krol’, V.P. Talzi, A.S. Belyi, 2016, published in Kinetika i Kataliz, 2016, Vol. 57, No. 4,
pp. 508–515.
Nonoxidative Conversion of Methane and n-Pentane
over a Platinum/Alumina Catalyst
D. V. Golinskiia, *, N. V. Vinichenkoa, b, V. V. Pashkova, I. E. Udrasa, O. V. Krol’a,
V. P. Talzia, and A. S. Belyia, b
aInstitute of Hydrocarbons Processing, Siberian Branch, Russian Academy of Sciences, Omsk, 644040 Russia
bOmsk State Technical University, Omsk, 644050 Russia
*e-mail: goldim1983@yandex.ru
Received September 8, 2015
Abstract—Methane adsorption on the Pt–H/Al2O3 and Pt/Al2O3 catalysts begins at Т = 475°C and is accom-
panied by the appearance of hydrogen in the reaction medium. At a higher temperature is raised to 550°C,
the amount of adsorbed hydrogen increases to 1.1 and 0.8 mol/(mol Pt), respectively. According to the cal-
culated degree of methane dehydrogenation on platinum sites at Т = 550°C, the Н/C ratio is 1.3 (at/at) for
the Pt–H/Al2O3 catalyst and 1.5 (at/at) for the Pt/Al2O3 catalyst. The introduction of n-pentane into the
reaction medium increases the yield of aromatic hydrocarbons (benzene and toluene) by a factor of 8.8 over
the arene yield observed in individual n-pentane conversion. A mass spectrometric analysis of the arenes
obtained with the Pt/Al2O3 catalyst has demonstrated that 37.5% of the adsorbed methane is involved in the
methane–n-pentane coaromatization yielding benzene and toluene.
Keywords: methane, n-pentane, isotope-ratio mass spectrometry, aromatic hydrocarbons
DOI: 10.1134/S0023158416040042
INTRODUCTION
cerning the co-conversion of methane with higher
hydrocarbons are practically lacking. The only works
in this area deal with the co-conversion of methane
with propane [10–12] and hexane [13] over zeolite
catalysts.
Here, we report methane chemisorption on a plat-
inum/alumina catalyst containing 1 wt % Pt and the
capacity of CНх fragments to undergo co-conversion
with n-pentane.
Methane is the main component of natural gas and
is viewed as the most promising raw material for pet-
rochemistry. Because of the high stability of the meth-
ane molecule, it was long believed that nonoxidative
methane conversion is possible only above 1000°C. At
present, the possibility of methane chemisorption on a
catalyst at moderate temperatures (200–450°C) with
the formation of CНх fragments and hydrogen mole-
cules is discussed in the literature [1–4]. Most of the
relevant studies were aimed at investigating the two-
step nonoxidative homologation of methane into C2+
hydrocarbons. Many transition metals supported on
various materials have been tested in this reaction to
date [1, 4–6].
EXPERIMENTAL
Catalyst Preparation
For preparing the catalyst, the initial γ-Al2O3 support
(SBET = 177.7 m2/g, Vpore = 0.68 cm3/g, dav = 154 Å) was
loaded with oxalic acid (3 wt %) from its aqueous solu-
tion. The resulting sample was dried at 120°C and cal-
cined in flowing dry air at 500°C. Next, platinum
(1 wt %) was deposited onto the sample from an H2PtCl6
solution mixed with dilute hydrochloric acid (1 wt %)
and dilute acetic acid (1.5 wt %). The resulting catalyst
was dried at 120°C, calcined in flowing dry air at
There has been a work dealing with one-step meth-
ane conversion over Pd–Co/SiO2 and Pt–Co/NaY
catalysts [7]. In addition, in the last five years there
have been studies on the catalytic activity of particular
faces of metal crystals, such as Ni(100), Ni(111), and
Ni(553) [8], and on the possibility of methane
chemisorption on platinum and palladium clusters
supported on graphenes and carbon nanotubes [9].
Thus, while two-step nonoxidative methane 500°C, and reduced in a hydrogen atmosphere at
homologation has been investigated fairly well for a 500°C. The dispersion of platinum in the catalyst,
large number of supported metal oxide catalytic sys- determined by oxygen titration of hydrogen pre-
tems typically containing 3–12 wt % metal, data con- adsorbed on the catalyst surface [14, 15], was 96%.
504

NONOXIDATIVE CONVERSION OF METHANE AND n-PENTANE
505
Catalytic Tests
source of the mass spectrometer. The sample to be
analyzed was ionized by an electron impact. The iso-
topic composition of the sample was determined ver-
sus a standard CО2 gas. The 13C content was calculated
using the VPDB international standard.
The adsorption properties of the catalysts were
studied in the temperature range from 20 to 550°C at
CН4 : Pt = 10 : 1 (mol/mol) in a perfect-mixing reac-
tor. A catalyst sample was pre-reduced in flowing dry
hydrogen at 500°C for 1 h. For investigating methane
adsorption on the surface of the catalyst containing
pre-adsorbed hydrogen (Pt–H/Al2O3), the reactor
was cooled to room temperature. Thereafter, the reac-
tor was fed with a methane : argon = 50 : 50 (vol/vol)
mixture. Argon was used as the internal standard. For
investigating methane adsorption on the “clean” sur-
face of the reduced sample (Pt/Al2O3), argon was sup-
plied into the reactor for 2 h at Т = 500°C to remove
weakly bound hydrogen from the catalyst surface;
thereafter, the catalyst was cooled to room tempera-
ture in flowing argon and was analyzed for hydrogen
content. Next, the methane : argon = 50 : 50 (vol/vol)
mixture was fed into the reactor. After the study of the
adsorption properties of the catalyst, n-pentane was
added to methane in the reaction mixture (C5H12 :
CН4 = 4 : 1, mol/mol) at Т = 550°C. The C5H12 + CН4
mixture was in contact with the Pt/Al2O3 catalyst for
3 min. n-Pentane was chosen to be the model hydro-
carbon for the following two reasons. Firstly, n-pen-
tane does not undergo direct aromatization and the
arenes appearing in the reaction medium can be
obtained only by methane–n-pentane coaromatiza-
tion or result from secondary reactions of n-pentane
with products of its cracking. Secondly, n-pentane is
thermodynamically more stable than its higher homo-
logues. Therefore, if it is demonstrated that methane
and n-pentane can undergo co-conversion over the
Pt/Al2O3 catalyst, it will be possible to state that the
higher homologues of n-pentane will participate in the
reaction as well and their reaction will be thermody-
namically still more favorable.
13C NMR Spectroscopy
The 13C NMR spectra of the catalysts after experi-
ments were recorded on an Аvance_400 NMR spec-
trometer (Bruker, Germany) with an SB4 multinu-
clear probe using a single-pulse technique with high-
power broadband proton decoupling (hpdec pulse
program, Bruker). A catalyst samples, ground in an
agate mortar, was placed in a zirconia rotor (Bruker,
Germany; d = 4 mm) with a plastic (Kel–F) cap, and
a spectrum was recorded at a spinning frequency of
1 kHz at a magic angle of 54.7° to the constant mag-
netic field direction. The Larmor frequency was
100.4 MHz. The pulse repetition time was 20–30 s.
The external standard was tetramethylsilane. The
experiment duration was 48 h.
Carbon Deposit Content Determination
Carbon deposits on the catalyst surface were quan-
tified by automatic coulometric titration on an
AN-7529 express analyzer (Russia).
RESULTS AND DISCUSSION
To see whether methane–n-pentane co-conver-
sion is thermodynamically allowable, we calculated
the change in the Gibbs energy of the system (ΔG).
Figure 1a how the change in the Gibbs energy varies
with temperature for the formation of benzene, tolu-
ene, xylenes, and n-hexane for the methane–n-pen-
tane mixture. It follows from these calculations that
benzene formation is possible near 800 K (527°C);
toluene formation, at 830 K. The formation of
xylenes can occur only at Т > 950 K. Note that n-hex-
ane formation is impossible in the temperature range
examined.
The methane that was used in the experiments was
99.9 vol % pure and was 13C-enriched to the extent of
99.9 at %. n-Pentane was 99.9 wt % pure.
Isotope-Ratio Mass Spectrometry
The extent of a reaction can be characterized in
terms of equilibrium conversion (Хeq). The numerical
values of Хeq for the thermodynamically possible reac-
tions in the system are presented in Fig. 1b [16].
Clearly, at Т = 823 K (550°C) Хeq for benzene forma-
tion is about 17%. The same equilibrium conversion
for toluene formation is reached at Т = 900 K; for the
formation of xylenes, it is reached at Т > 1000 K
because of the lower thermodynamic probability of
the reaction taking place.
The stable carbon isotopes (13C and 12C) in the
feedstock and reaction products were quantified on a
DELTA V Advantage magnetic-sector mass spectrom-
eter (Thermo Fisher Scientific, Germany). The sam-
ple was separated in a capillary column (60 m ×
0.25 mm × 1.0 mm, Thermo Fisher Scientific) in the
temperature-programmed mode while raising the
temperature from 40 to 180°C at a rate of 3°C/min at
a constant carrier gas (helium) flow rate of
0.8 mL/min. The components leaving the chromato-
graph were directed to an oxidation reactor (Т =
Methane adsorption on the platinum/alumina cata-
1030°C), and the, resulting CО2 was passed through a lyst containing pre-adsorbed hydrogen (Pt–H/Al2O3)
Nafion drier (Thermo Fisher Scientific, Germany) begins at 475°C (0.1 mol/(mol Pt)), as is shown in
and a ConFlo IV gas preparation block (Thermo Fig. 2a. As the reaction temperature is elevated to
Fisher Scientific) and was then admitted in the ion 550°C, the amount of adsorbed methane increases to
KINETICS AND CATALYSIS Vol. 57 No. 4 2016

506
GOLINSKII et al.
mol/(mol Pt)
(а)
(а)
ΔG, kJ/mol
300
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
3
H2
250
2
CH4
200
1
150
100
50
4
0
200 300 400 500 600 700 800 900 1000
–50
–100
T, K
–150
400 425 450 475 500 525 550 575
(b)
T, °C
Xeq, % CH4, C5H12
(b)
100
1
H/C, at/at
80
60
40
20
0
4.0
3.5
3.0
2.5
2.0
1.5
2
3
200 300 400 500 600 700 800 900 1000
T, K
1.0
400 425 450 475 500 525 550 575
Fig. 1. (a) Change in the Gibbs energy and (b) equilib-
rium conversion of methane and n-pentane as a function
T, °C
Fig. 2. (a) Amount of methane adsorbed and the amount
of hydrogen released as a result of methane adsorption for
the Pt–H/Al O catalyst; (b) Н/C ratio in the adsorbed
of the reaction temperature for the reactions (1) CН +
4
C Н = C Н + 5Н , (2) 2CН + C Н = C Н + 6Н ,
5
12
6
6
2
4
5
12
7
8
2
+
(3) 3CН + C Н = C Н + 7Н , and (4) CН
2
3
4
5
12
8
10
2
4
hydrocarbon fragments.
C Н = C Н + Н .
5
12
6
14
2
the amount of the latter was thoroughly measured in
our earlier study [17]. The 1.5 (mol Н2)/(mol Pt) value
1.1 mol/(mol Pt). The onset of methane adsorption at
Т = 475°C is accompanied by the appearance of
hydrogen in the reaction medium. Raising the tem- was obtained by subtracting the amount of weakly
bound hydrogen desorbed from the catalyst from the
total amount of Н2 in the system.
perature to 550°C increases the Н2 content to
1.5 mol/(mol Pt). It follows from these data that
hydrogen adsorption is dissociative and slightly over-
stoiciometric. Apparently, owing to hydrogen diffu-
sion from platinum to the support (spillover), part of
the adsorbed methane, undergoing dehydrogenation,
is transferred to the Al2O3 surface. Along with the
hydrogen that is released as a result of methane adsorp-
tion, the hydrogen desorbed from the surface of the
Pt–H/Al2O3 catalyst is present in the reaction medium;
From the amounts of adsorbed methane and
released hydrogen, we derived the degree of methane
dehydrogenation over the platinum sites (Fig. 2b). At
the onset point of adsorption, the average Н/C value
for the hydrocarbon fragments on the surface is
2.8 at/at. An increase in the adsorption temperature
leads to a deeper methane hydrogenation down to
H/C = 1.3 (at/at). It turns out that a considerable part
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NONOXIDATIVE CONVERSION OF METHANE AND n-PENTANE
507
of methane is low-active at 550°C. Apparently, the
(а)
CНх fragments resulting from methane adsorption are
structurally inhomogeneous.
mol/(mol Pt)
1.0
0.8
0.6
0.4
0.2
0
H2
Methane adsorption on the catalyst surface con-
taining no pre-adsorbed hydrogen (Pt/Al2O3) also
begins at Т = 475°C (Fig. 3a). The amount of methane
converted in this case is 0.3 mol/(mol Pt), and the
amount of released hydrogen is 0.1 mol/(mol Pt).
Raising the reaction temperature to 550°C increases
the amount of methane adsorbed to 0.8 mol/(mol Pt)
and increases the amount of hydrogen released to
1.0 mol/(mol Pt). Calculation of the degree of hydro-
genation of adsorbed methane on platinum sites
demonstrates (Fig. 3b) that, at the onset temperature
of adsorption (Т = 475°C), Н/C = 3.3 (at/at). Elevat-
ing the temperature to 550°C causes further hydrogen
abstraction yielding H-deficient hydrocarbon frag-
ments with Н/C = 1.5 (at/at) on the surface.
The above data on methane adsorption on the
Pt–H/Al2O3 and Pt/Al2O3 catalysts suggest that, in
both cases, methane conversion begins at Т = 475°C.
However, at 550°C the amount of methane adsorbed
for the Pt–H/Al2O3 sample (1.1 mol/(mol Pt)) is
larger than for Pt/Al2O3 (0.8 mol/(mol Pt)). Further-
more, calculations demonstrated that methane on the
Pt/Al2O3 catalyst is dehydrogenated to a lesser extent
(Н/C = 1.5 (at/at)) than methane on the Pt–H/Al2O3
catalyst (Н/C = 1.3 (at/at)).
A comparison between the above data and the
results obtained for the two-step methane homologa-
tion yielding C2+ hydrocarbons [1–4] reveals signifi-
cant distinctions between the methane adsorption reg-
ularities in these processes. When the two-step meth-
ane conversion process was studied on low-dispersion
catalysts with a high metal content (which was usually
the case), adsorption began near 150°C and, once a
temperature of Т = 350°C was reached, only unreac-
tive graphite-like fragments were identified on the sur-
face. In the Pt/Al2O3 catalyst, platinum sites are highly
dispersed because of the relatively low metal content
and there are no Pt–Pt bonds [18]. This is likely the
reason why the onset of adsorption shifts to higher
temperatures (Т = 475°C). This fact is thermodynam-
ically favorable for methane–n-pentane co-conver-
sion taking place.
CH4
400 425 450 475 500 525 550 575
T, °C
(b)
H/C, at/at
4.0
3.5
3.0
2.5
2.0
1.5
400 425 450 475 500 525 550 575
T, °C
Fig. 3. (a) Amount of methane adsorbed and the amount
of hydrogen released as a result of methane adsorption for
the Pt/Al O catalyst; (b) Н/C ratio in the adsorbed
2
3
hydrocarbon fragments.
was introduced into the reactor at 550°C (Table 1).
This increased the n-pentane conversion to 87.3%.
The hydrogen yield was 6.0 mol/(mol Pt), and the
yield of gaseous hydrocarbons, which were dominated
by methane, was 30.3 mol/(mol Pt). The total arene
We studied the conversion undergone by n-pentane
over the Pt–H/Al2O3 catalyst at Т = 550°C (Table 1).
The n-C5Н12 conversion value was 84.5%. The hydro-
gen yield was 5.6 mol/(mol Pt), and the yield of gas-
eous hydrocarbons (methane, ethane, propane,
butanes) was 25.9 mol/(mol Pt). The reaction prod-
ucts contained a small amount of isopentane
(0.3 mol/(mol Pt)). Aromatic hydrocarbons were rep-
resented by benzene (0.9 mol/(mol Pt)) and toluene
(0.4 mol/(mol Pt)). For investigating the reactivity of
the CНх fragments appearing on the Pt–H/Al2O3 sur-
yield increased by
a factor of 2.5 (benzene,
1.1 mol/(mol Pt); toluene, 2.1 mol/(mol Pt)) over the
arene yield observed for individual n-pentane.
Thus, although for the Pt–H/Al2O3 catalyst the
Н/C ratio at Т = 550°C is 1.3 (at/at), the hydrocarbon
fragments that have formed from methane react with
n-pentane to yield benzeneа. Therefore, on the surface
face as a result of methane decomposition, n-pentane of this catalyst there are catalytically active fragments
KINETICS AND CATALYSIS Vol. 57 No. 4 2016

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GOLINSKII et al.
Table 1. Hydrocarbon yields on the converted n-pentane
In the case of n-pentane admitted to adsorbed
methane, the n-C5Н12 conversion is 79.3% (Table 2).
The amount of hydrogen in the reaction medium is
6.5 mol/(mol Pt), and the amount gaseous hydrocar-
bons there is 21.6 mol/(mol Pt). The arene yield
increases markedly: the benzene yield rises to
3.1 mol/(mol Pt); the toluene yield, to 1.3 mol/(mol Pt).
basis for the Pt–H/Al2o3 catalyst
Initial reactants
Reaction products,
methane +
n-pentane**
mol/(mol Pt)
n-pentane*
Hydrogen
Methane
Ethane
Propane
Butanes
Isopentane
n-Pentane
Benzene
Toluene
5.6
7.7
8.6
7.5
2.1
0.3
6.2
0.9
0.4
6.0
22.8
5.1
The catalytic testing data for the Pt–H/Al2O3 and
Pt/Al2O3 samples indicate that, on passing from the
methane–n-pentane co-conversion to the conversion
of individual n-pentane, the product composition
does not change qualitatively and only quantitative
changes take place, primarily in the proportions of the
resulting gaseous hydrocarbons. The main advantage
of the hydrocarbon co-conversion process is that it
affords a higher arene yield. For example, the arene
yield in this process is 2.5 higher with the Pt–H/Al2O3
catalyst and 8.8 higher with the Pt/Al2O3 catalyst.
1.8
0.6
0.4
5.1
1.1
2.1
* Pentane conversion: 84.5%.
** Pentane conversion: 87.3%.
The aromatic hydrocarbons resulting from enriched
methane–n-pentane co-conversion over Pt/Al2O3 were
analyzed by isotope-ratio mass spectrometry. The study
of the isotopic composition of carbon demonstrated
that the benzene molecules contain 0.2 mol 13C, and the
toluene molecules contain 0.1 mol 13C (Fig. 4). There-
fore, of the total amount of synthesized benzene
(3.1 mol/(mol Pt)), 0.2 mol/(mol Pt) benzene mole-
cules are obtained with the participation of 13CH4; of the
total amount of synthesized toluene (1.3 mol/(mol Pt)),
0.1 mol/(mol Pt) toluene molecules contain 13C from
13CН4. From these data and the amount of methane
adsorbed at 550°C on the Pt/Al2O3 catalyst
(0.8 mol/(mol Pt)), it can be derived that 37.5% of the
adsorbed 13CНх molecules are involved in the forma-
tion of aromatic hydrocarbons. It is apparently this pro-
portion of the catalytically active 13CНх fragments
resulting from methane adsorption occur on platinum
sites at Н/C = 1.5 (at/at). The rest benzene molecules
(2.9 mol/(mol Pt)) and toluene molecules
(1.2 mol/(mol Pt)) form without involving 13CН4;
most likely, they form from gaseous hydrocarbons
resulting from n-pentane cracking. It is clear from the
above calculations that the increase in the arene yield
on passing from the conversion of n-pentane alone to
the co-conversion of 13CН4 + C5Н12 is inconsistent with
the amount of arenes formed from the reacted meth-
aneу. It is likely that the methane present in the reaction
medium along with n-pentane shifts the reaction toward
aromatization rather than cracking.
Reaction conditions: Т = 550°C, CН /Pt = 10/1 (mol/mol),
4
CН /C Н = 1/4 (mol/mol).
4
5
12
Table 2. Hydrocarbon yields on the converted n-pentane
basis for the Pt/Al2O3 catalyst
Initial reactants
Reaction products,
methane +
mol/(mol Pt)
n-pentane*
n-pentane**
Hydrogen
Methane
Ethane
Propane
Butanes
Isopeentane
n-Pentane
Benzene
Toluene
5.9
17.1
15.5
10.4
4.7
2.1
8.4
0.4
0.1
6.5
17.7
3.2
0.7
0.0
0.4
8.3
3.1
1.3
* Pentane conversion: 79.0%.
** Pentane conversion: 79.3%.
Reaction conditions: Т = 550°C, CН /Pt = 10/1 (mol/mol),
4
CН /C Н = 1/4 (mol/mol).
4
5
12
along with Н-deficient ones. This is also indicated by
the fact that the benzene yield in the methane–n-pen-
tane co-conversion is higher than in the conversion of
n-pentane alone.
In the case of the individual conversion of n-pen-
tane over the Pt/Al2O3 catalyst, the n-pentane conver-
sion value reaches 79.0% (Table 2). The amount of
hydrogen released in this case is 5.9 mol/(mol Pt), and
the yield of C1–C4 gases is 47.7 mol/(mol Pt). The
benzene yield (0.4 mol/(mol Pt)) and toluene yield
(0.1 mol/(mol Pt)) are lower than the corresponding
yields observed for Pt–H/Al2O3.
After the 13CН4 + n-C5Н12 co-conversion experi-
ment, 0.2 wt % carbon (3.4 mol/(mol Pt)) was depos-
ited on the Pt/Al2O3 surface. Calculations demon-
strated that the methane remaining adsorbed on plati-
num sites (62.5%) can yield 0.5 mol carbon per mole of
Pt. The rest of the carbon deposit, 2.9 mol/(mol Pt),
likely resulted from n-pentane decomposition.
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NONOXIDATIVE CONVERSION OF METHANE AND n-PENTANE
509
13
С
13
0.1 mol/(mol Pt)
0.2 mol/(mol Pt)
H
13
13
Pt
13
13
Pt
13
13
13
Pt
Pt
Al2O3
Al2O3
2.9 mol/(mol Pt)
1.2 mol/(mol Pt)
Fig. 4. Isotopic composition of carbon in aromatic hydrocarbons.
The structure of the carbon deposit was studied by This maximum indicates the presence of a coke
13C NMR spectroscopy. Figure 5 shows a fairly inten-
sive maximum in the resonance range of sp2-hybrid-
ized carbon, whose chemical shift is 120–130 ppm.
deposit in the form of nanosized graphene clusters on
the catalyst surface. The observed graphene structures
might result both from the decomposition of adsorbed
methane and from the condensation of arene precur-
sors that had formed via the reaction between methane
and n-pentane. For the sake of comparison, we pres-
ent, in Fig. 5, the 13C NMR spectrum of the Pt/Al2O3
sample that has been tested in 12CH4–n-pentane co-
conversion. Clearly, the signal at 120–130 ppm in this
spectrum is much weaker than the same signal in the
spectrum of the previous catalyst sample, even though
the experimental conditions were identical. Therefore,
13C is definitely present in the structure of the
graphene clusters in the experiments involving 13CН4.
*
1
The less intense and less broad signal at 30 ppm is
evidence of the presence of n-alkanes on the catalyst
surface. Most likely, these are traces of unreacted
n-pentane. The magic angle spinning satellites in the
spectrum are labeled with symbol *.
2
200 180 160 140 120 100 80 60 40 20
0
ppm
Thus, this study demonstrated that methane
adsorption on the Pt–H/Al2O3 and Pt/Al2O3 catalysts
begins at 475°C, accompanied by the appearance of
13
Fig. 5. C NMR spectra of the Pt/Al O catalyst recorded
after the (1) CН + C Н and (2) CН + C Н co-
2
3
13
12
4
5
12
4
5
12
conversions.
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4. Belgued, M., Amagirlio, A., Lefort, A., Pareja, P., and
hydrogen in the reaction medium. as the temperature
is raised to 550°C the amount of methane adsorbed
increases to 1.1 and 0.8 mol/(mol Pt), respectively.
According to the calculated degree of methane dehy-
drogenation on platinum sites at 550°C, the Н/C ratio
for the Pt–H/Al2O3 catalyst is 1.3 (at/at) and the same
ratio for the Pt/Al2O3 sample is 1.5 (at/at). The intro-
duction of n-pentane into the methane-containing
reaction medium markedly increases the yield of aro-
matic hydrocarbons (benzene and toluene). An iso-
tope-ratio mass spectrometric analysis of the arenes
resulting from the reaction over the Pt/Al2O3 catalyst
demonstrated that 37.5% of the adsorbed methane is
involved together with n-pentane in benzene and tolu-
ene formation. Apparently, it is this proportion of the
catalytically active 13CНх occurs on platinum sites at
Н/C = 1.5 (at/at). Unreacted methane and the con-
densed arene precursors that have resulted from the
Amagirlio, H., J. Catal., 1996, vol. 161, p. 282.
5. Martins, R.L., Baldanza, M.A.S., Souza, M.M.V.M.,
and Schmal, M., Appl. Catal., A, 2007, vol. 318, p. 207.
6. Koerts, T., Deelen, M.J.A.G., and Santen, R.A.,
J. Catal., 1992, vol. 138, p. 101.
7. Guczi, L. and Borco, L., Catal. Today, 2001, vol. 64,
p. 91.
8. Li, J., Croiset, E., and Ricardez-Sandoval, L., J. Mol.
Catal. A: Chem., 2012, vol. 365, p. 103.
9. Russell, J., Zapol, P., Kral, P., and Curtiss, L.A., Chem.
Phys. Lett., 2012, vol. 536, p. 9.
10. Shen, X.C., Lou, H., Hu, K., and Zheng, X.M., Chin.
Chem. Lett., 2007, vol. 18, p. 479.
11. Zheng, L., Xuan, D., Guo, J., Lou, H., and Zheng, X.,
J. Nat. Gas Chem., 2006, vol. 15, p. 52.
12. Guo, J., Lou, H., and Zheng, X., J. Nat. Gas Chem.,
2009, vol. 18, p. 260.
interaction between methane and n-pentane but have 13. Anunziata, O.A., Mercado, G.G., and Pierella, L.B.,
Catal. Commun., 2004, vol. 5, p. 401.
not been desorbed into the gas medium remain as
graphene clusters on the catalyst surface.
It was demonstrated that aromatic hydrocarbons
can be synthesized on highly dispersed platinum via
the co-aromatization of methane and n-pentane over
a platinum/alumina catalyst under mild reaction con-
ditions.
14. Belyi, A.S., Kiryanov, D.I., Smolikov, M.D.,
Zatolokina, E.V., Udras, I.E., and Duplyakin, V.K.,
React. Kinet. Catal. Lett., 1994, vol. 53, no. 1, p. 183.
15. Belyi, A.S., Extended Abstract of Doctoral (Chem.) Dis-
sertation, Novosibirsk: Inst. of Cata;ysis, 2002.
16. Zhorov, Yu.M., Termodinamika khimicheskikh prot-
sessov (Chemical Thermodynamics), Moscow:
Khimiya, 1985.
17. Golinsky, D.V., Ostanina, N.V., Ovcharenko, A.I.,
Pashkov, V.V., Udras, I.E., and Beliy, A.S., Procedia
Eng., 2015, no. 113, p. 13.
REFERENCES
1. Belgued, M., Amagirlio, A., Pareja, P., and Amagirlio, H.,
J. Catal., 1996, vol. 159, p. 441.
18. Belyi, A.S., Smolikov, M.D., Kir’yanov, D.I., and
2. Belgued, M., Amagirlio, A., Pareja, P., and Amagirlio, H.,
Udras, I.E., Ross. Khim. Zh., 2007, vol. 41, no. 4, p. 38.
J. Catal., 1996, vol. 159, p. 449.
3. Amagirlio, A., Pareja, P., and Amagirlio, H., Catal.
Translated by D. Zvukov
Today, 1995, vol. 25, p. 113.
KINETICS AND CATALYSIS
Vol. 57
No. 4
2016