Features of Butene-1 Adsorption on H-Beta Zeolite

Article abstract of DOI:10.1134/S0036024419010321

Abstract: The adsorption of butene-1 on Beta zeolite (H form) is studied via flow-adsorption calorimetry. Upon feeding a mixture of 2 vol % of butene-1 in nitrogen over the pre-calcined zeolite (500°C) at room temperature, an exothermic effect is observed that is associated with the adsorption and transformations of butene, particularly its isomerization to cis- and trans-butenes-2. The thermal desorption of adsorbed butene?1 results in formation of hydrocarbon products showing that oligomerization proceeds during adsorption. It is found that zeolite pretreated with moist nitrogen adsorbs water up to 9.2 wt %. A?weak exothermic effect is observed when butene-1 is adsorbed on this rehydrated zeolite, due apparently to the physical adsorption of butene-1. When the rehydrated zeolite is held for long periods of time in a stream of a butene/nitrogen mixture, cis-butene-2 is detected at the reactor outlet, indicating the gradual replacement of water with butene-1 on the active sites of zeolite.

Full text of DOI:10.1134/S0036024419010321

ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2019, Vol. 93, No. 1, pp. 177–180. © Pleiades Publishing, Ltd., 2019.
Russian Text © E.A. Volnina, M.A. Kipnis, S.N. Khadziev, 2019, published in Zhurnal Fizicheskoi Khimii, 2019, Vol. 93, No. 1, pp. 154–157.
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Features of Butene-1 Adsorption on H-Beta Zeolite
E. A. Volninaa, M. A. Kipnisa,*, and S. N. Khadzieva†
a Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, 119991 Russia
*е-mail: kipnis@ips.ac.ru
Received March 20, 2018
Abstract—The adsorption of butene-1 on Beta zeolite (H form) is studied via flow-adsorption calorimetry.
Upon feeding a mixture of 2 vol % of butene-1 in nitrogen over the pre-calcined zeolite (500°C) at room tem-
perature, an exothermic effect is observed that is associated with the adsorption and transformations of
butene, particularly its isomerization to cis- and trans-butenes-2. The thermal desorption of adsorbed
butene-1 results in formation of hydrocarbon products showing that oligomerization proceeds during adsorp-
tion. It is found that zeolite pretreated with moist nitrogen adsorbs water up to 9.2 wt %. A weak exothermic
effect is observed when butene-1 is adsorbed on this rehydrated zeolite, due apparently to the physical adsorp-
tion of butene-1. When the rehydrated zeolite is held for long periods of time in a stream of a butene/nitrogen
mixture, cis-butene-2 is detected at the reactor outlet, indicating the gradual replacement of water with
butene-1 on the active sites of zeolite.
Keywords: butene-1, adsorption, zeolite, isomerization, oligomerization
DOI: 10.1134/S0036024419010321
INTRODUCTION
ture was studied by the flow-adsorption calorimetry
used in studying the adsorption of isobutane and
isobutene on a number of zeolites [7, 9].
The reactions of light alkenes on solid acid cata-
lysts, particularly isomerization, are actively being
investigated. For example, the isomerization of
butene-1 to form isobutene on a series of zeolites in the
H form at 400°C was studied in [1, 2]; the oligomeri-
zation of propene and butene-1 on H-zeolites and alu-
minosilicates at 230°C were studied in [3]. The skeletal
isomerization of butene-1 to isobutene on ferrierite at
400°C was reported in [4]; that of butene-1 to form
butene-2 at room temperature on Pd-containing Beta
zeolites and ZSM-5 was investigated in [5]. The oligo-
merization of isobutene at 40–100°C on a number of
zeolites was reported in [6].
EXPERIMENTAL
Characterization of Zeolite
Beta zeolite was used in ammonium form (manu-
factured by OAO AZK and OS). To remove the
organic template from the initial zeolite and transfer it
to the H form, it was calcined for 2 h at 500°C. Ele-
mental analysis was performed on an improved ARL
Perform’x wave X-ray fluorescence spectrometer.
The temperature programmed desorption (TPD)
of ammonia was conducted on a USGA-101 sorption
analyzer (Unisit, Russia). The zeolite was pressed into
pellets, crushed and sieved. The 0.2–0.5 mm fraction
was calcined in a stream of dried helium at 550°C and
cooled to 60°C. The adsorption of ammonia was con-
ducted for 30 min at 60°C from a stream containing
10% ammonia in nitrogen. Physically adsorbed
ammonia was purged out for 1 h in a stream of dried
helium at 100°C. TPD of NH3 was conducted in a
stream of dried helium (flow rate, 30 mL/min) in the
temperature range of 60 to 700°C at a heating rate of
8 K/min.
It was found in [7] that the adsorption of isobutene
on HY zeolite promoted by Ca and La is affected by
the dehydration temperature of the zeolite. Lowering
the dehydration temperature from 500 to 130°C alters
the character of the exothermic effect associated with
the adsorption and transformations of isobutene. We
may assume this is due to the presence of hydroxyls in
the case of low heat treatment temperatures. The
effect water has on the isomerization of butene-1 to
isobutene on supported heteropolyacid (H4SiW12O40)
was reported in [8]; according to the authors, adding
water positively affects conversion, reducing the cok-
ing of active sites.
The mass loss curves of the samples of the initial
and rehydrated zeolite were obtained using a
SDTQ600 thermal analyzer (heating rate, 8 K/min;
heating to 600°C).
In this work, the effect water has on the adsorption
of butene-1 on the H-Beta zeolite at room tempera-
†
Deceased.
177

178
V, μm/(g s)
VOLNINA et al.
calcined in the reactor in a nitrogen flow at 500°C for
1 h and cooled to room temperature under a stream of
nitrogen. To rehydrate the calcined zeolite at room
temperature, nitrogen was passed through a water sat-
urator before entering the reactor. Rehydration was
monitored by observing the temperature measured
with the thermocouple placed in the sample layer:
water adsorption was accompanied by a substantial
exothermic effect. As the sample was saturated with
water, the temperature of the layer fell and approached
its initial value. A weak endoeffect was observed when
a rehydrated sample was purged with dry nitrogen,
indicating the removal of loosely bound water.
0.8
0.6
0.4
0.2
Chromatographic analysis of the hydrocarbons was
performed on a Chrom 5 chromatograph with flame
ionization detector, equipped with 23% SP-1700 col-
umn (Supelco).
0
200
400
600
T, °C
Fig. 1. Spectrum of the temperature programmed desorp-
tion of ammonia on H-Beta zeolite.
RESULTS AND DISCUSSION
Physicochemical Data
Study of Adsorption
According to elemental analysis, the content of
SiO2 and Al2O3 corresponded to silicate module of 29.
Impurities included oxides (wt %) of Ca (0.6), Mg
(0.4), Fe (0.1), and Na (0.08). According to the ther-
mogravimetric analysis data, organic matter was
removed from the initial zeolite in the temperature
range of 420–480°C. Zeolite in the H form was stud-
ied via the TPD of ammonia. The corresponding
spectrum is shown in Fig. 1. The form of the thermal
desorption curve indicates the presence of at least two
types of centers that differ considerably in energy. The
total acidity was 1045 μmol ammonia/g (670 μmol
ammonia/g was desorbed in the range of 55–300°C,
and 375 μmol ammonia/g at temperatures above
300°C).
According to thermogravimetric analysis data, the
weight loss of rehydrated zeolite was 9.2% upon calci-
nation to 600°C. The maximum weight loss peak
(~100°C) was associated with the release of molecu-
larly bound water. The study of the sample weight loss,
performed with an intermediate step at 120°C (20 min
of exposure were needed for the DTG curve to reach a
plateau) showed that upon subsequent heating from
120 to 500°C, 0.026 g of water (calculated with respect
to 1 g of calcined zeolite) was removed. This weight
loss can be attributed to the dehydroxylation of zeolite.
The scheme of the flow setup used in our experi-
ments was given in [9]. The main parts of the setup are
a quartz reactor with ground glass joints for incoming
gas, a thermocouple controlling the temperature of
the sample layer, an electric furnace, regulators, and
flow and pressure meters. In the reactor (internal
diameter, 13 mm) placed in an electric furnace, a sam-
ple of the zeolite was charged onto a porous quartz
insert. One or two thermocouples of the KTKhA
K-type (“TESEY”) with shell diameters of 1 mm were
used to measure the heat effects. The thermocouple
junctions were placed at the inlet and outlet level of the
layer. The height of the layer was 14 mm for a sample
weighing 0.6 g.
The flow rate of the gas (55–60 mL/min) was set
using a pressure regulator and a fine adjustment valve,
and measured at the inlet and outlet of the reactor with
IRG-100 meters. The inlet and outlet pressure of the
reactor was monitored by pressure sensors. The gas
circuit of the setup was equipped with two three-way
valves (located before and after the reactor) allowing
us to direct the flow of gas into the reactor or to bypass
it. By combining the corresponding valve turns, we
can also pressurize the reactor to check its airtightness.
To operate with wet nitrogen, a six-way valve and a
water saturator were installed at the inlet to the reactor.
The temperature, flow, and pressure values were mon-
itored on a PC using a special program (developed by
A.S. Korotkov).
Adsorption Studies on Calcined Zeolite
The adsorption of butene-1 at room temperature
on pre-calcined zeolite was accompanied by a sub-
stantial exothermic effect (Fig. 2) and the formation of
cis- and trans-butenes-2 (Fig. 3). Maximum heating
was observed at the output end of the layer. The initial
increase in temperature at the output end of the layer
A mixture of 2 vol % of C4H8 in nitrogen was used
in the adsorption experiments. We used 1-butene with
a purity of 99.5% (Linde AG). The mixture was pre-
pared according to the partial pressures of the compo-
nents in a pre-evacuated gas cylinder.
Our studies were performed on a pre-calcined zeo- was in this case ~7°C. We believe the rapid initial rise
lite. The weighed amount of zeolite after was further in temperature reflects the adsorption of butene-1,
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FEATURES OF BUTENE-1 ADSORPTION
179
associated with the adsorption of butene-1 (Fig. 2)
were related not only to adsorption and isomerization
but also to the oligomerization of butene-1, and possi-
bly its products. At the same time, the formed prod-
ucts apparently kept the isomerization reactions from
proceeding, resulting in the gradual drop in the isomer
yield (Fig. 3a).
T, ꢀC
32
1
30
28
26
24
2
Adsorption Studies on Rehydrated Zeolite
Adsorbed water had a substantial effect on the
adsorption of butene-1: the thermal adsorption effect
fell sharply (Fig. 4a), no trans-butene-2 was found in
gas products, and the content of cis-butene-2 was
greatly reduced, compared to adsorption on the cal-
cined sample (compare Figs. 3a and 4b). In addition,
upon adsorption of butene-1 on the rehydrated sam-
ple, the exothermic effect of adsorption of butene-1
was followed by a sequential endothermic effect
(interval 70–130 min), due apparently to the partial
desorption of weakly adsorbed water in the stream of
the gas mixture.
0
100
200
300
400
t, min
Fig. 2. Effect of temperature on the adsorption of butene-
1 on calcined zeolite Beta at room temperature: (1) and (2)
denote the temperatures at the outlet from the layer and
inlet to the layer, respectively. Sample weight, 0.64 g. The
arrow marks the initial moment of adding the butene-1/N
mixture (2 vol %).
2
while the character of the exothermic effect was subse-
quently affected by the proceeding reactions. The for-
mation of isomers characteristically passed through a
maximum and gradually fell (Fig. 3a) as the ratio of
cis/trans-butenes-2 rose monotonically from 1.8 to 8
over 4 h (Fig. 3b). When the mixture was replaced by
nitrogen, gradually diminishing traces of isomers were
detected for 0.5 h, and traces of butene-1 were
observed for 1.5 h at the outlet of the reactor. The sam-
ple weight grew relative to the initial value by 0.6 wt %.
After starting the mixture feed, cis-butene-2
appeared on the reactor outlet (Fig. 4b). Its content
grew over time, indicating the displacement of the
adsorbed water by butene. There was no trans-butene-
2, however, due apparently to water being adsorbed
more strongly at the centers associated with its forma-
tion. The content of butene-1 at the outlet from the
reactor quickly stabilized at a value of ~1.85 vol %.
Since the butene-1 content in the initial mixture was
2 vol %, the difference of 0.15 vol % can be attributed
to the adsorption of butene-1 on zeolite. When the
mixture was replaced by nitrogen (~310 min), an
appreciable endothermic effect was thus observed,
and the butene-1 content at the reactor fell drastically
When the experiment was repeated with the
adsorption of butene-1 followed by heating of the
sample in a stream of nitrogen, not only butenes-2 but
also isobutane, butane, pentane, pentenes, and methyl
pentanes were observed to form when heating to
200°C. This suggests the observed temperature effects (over 290–323 min) and then slowly for 80 min.
Butene-1, vol %
Isomers, vol % Kcis/trans
(а)
1.5
(b)
1
0.2
0.1
0
8
6
4
2
0
2
1.0
0.5
0
3
0
100
200
300
t, min
0
100
200
t, min
300
Fig. 3. (a) Yield of hydrocarbons upon the adsorption of butene-1 on calcined zeolite Beta at room temperature: (1) butene-1,
(2) cis-butene-2, (3) trans-butene-2. (b) Time dependence of cis/trans-butenes ratio. Sample weight, 0.64 g.
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 93 No. 1 2019

180
VOLNINA et al.
T, °C
(а)
1
24
23
22
21
20
2
0
100
200
300
400
t, min
Butene-1, vol %
2.0
cis-Butene-2, vol %
0.03
(b)
1.5
1
0.02
0.01
0
1.0
0.5
0
2
0
100
200
300
400
t, min
Fig. 4. Influence of water on the thermal effect of the adsorption of butene on rehydrated Beta zeolite at room temperature. The
arrows indicate the initial times of adding the C H /N mixture (2%) and nitrogen (dotted line). Sample weight, 0.62 g.
4
8
2
(a) Dynamics of the layer temperature: (1, 2) are the temperatures at the outlet from the layer and the inlet to the layer, respec-
tively. (b) Content of butenes at the reactor outlet: (1) butene-1, (2) cis-butene-2.
3. M. L. Sarazen, E. Doskocil, and E. Iglesia, J. Catal.
CONCLUSIONS
344, 553 (2016).
Butene-1 displaces adsorbed water, as is clear from
4. Y. Lee, M. B. Park, P. S. Kim, et al., ACS Catal. 3, 617
the increase in the isomer content (Fig. 3b). Under cer-
tain conditions, however, water can compete with
butene-1 for the active sites of the H-Beta zeolite.
(2013).
5. Y. Li, C. Ma, H. Yang, et al., Chem. Eng. J. 299, 1
(2016).
6. J. W. Yoon, J.-S. Chang, H.-D. Lee, et al., J. Catal.
ACKNOWLEDGMENTS
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L. I. Rodionova, M. V. Belova, and A. S. Korotkov, Pet.
Chem. 55, 127 (2015).
This work was performed as part of a State Program
of TIPS, Russian Academy of Sciences. It was sup-
ported by the Federal Agency for Scientific Organiza-
tions (Russia).
8. J. Zhang, R. Ohnishi, Y. Kamiya, and T. Okuhara,
J. Catal. 254, 263 (2008).
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