In Situ Formation of Al(Fe)/Cl Metal Chloride Complexes and Evaluation of Their Catalytic Properties in the Reaction of Ethylene Oligomerization

Article abstract of DOI:10.1134/S1070427217120059

The reactivity of the Al/Fe alloy with respect to organochlorine compounds for producing in situ catalytic (Fe-, Al/Cl) complexes from the systems Al/Fe/ tert-butyl chloride (TBC) and Al/Fe/TBC in n-hexane was investigated, together with their catalytic p

Full text of DOI:10.1134/S1070427217120059

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2017, Vol. 90, No. 12, pp. 1926−1930. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © A.B. Arbuzov, E.N. Kudrya, M.V. Trenikhin, V. A. Drozdov, 2017, published in Zhurnal Prikladnoi Khimii, 2017, Vol. 90, No. 11, pp. 1595−1599.
CATALYSIS
In Situ Formation of Al(Fe)/Cl Metal Chloride Complexes
and Evaluation of Their Catalytic Properties
in the Reaction of Ethylene Oligomerization
A. B. Arbuzova,b,*, E. N. Kudrya , M. V. Trenikhin , and V. A. Drozdov
a
a,b
a
a
Institute of Hydrocarbons Processing, Siberian Branch, Russian Academy of Sciences,
ul. Neftezavodskaya 54, Omsk, 644040 Russia
Omsk Scientific Center, Siberian Branch, Russian Academy of Sciences, Omsk, 644024 Russia
b
*
e-mail: arbuzov1410@mail.ru
Received November 7, 2017
Abstract—According to FT-IR and UV spectroscopic data, the interaction of theAl/Fe alloy with tert-butyl chlo-
–
4
–
7
+
3+
ride results in that AlCl , Al Cl , and FeCl ion complexes, Fe ions, and AlCl molecular form are produced in
2
2
3
situ in the reaction medium. Ethylene was oligomerized in n-hexane on metal chloride complexes produced in
situ from Al/Fe alloys and tert-butyl chloride.
DOI: 10.1134/S1070427217120059
Raising the selectivity of practically important re-
actions in which hydrocarbons are converted, such as
alkylation, oligomerization, and isomerization, is among
fundamental tasks of organic chemistry and catalysis.
Recently, in situ methods have become widely accepted
for synthesis of catalytic aluminum chloride complexes
from activated aluminum and organochlorine compounds,
which are active in the liquid-phase alkylation of iso-
butane with butenes [1], oligomerization of decene-1
to determine their catalytic properties under the chosen
conditions in the reaction of ethylene oligomerization.
EXPERIMENTAL
We used in the study the A/Fe alloy containing
2
.15 wt % Fe [8].
In situ formation of metal chloride complexes.
(
a) A 0.05–0.15-g alloy sample was placed in a
[
2], and transformations of cyclohexene into dimeth-
Teflon reactor and then 10 mL of TBC was added. After
the sample was completely dissolved at a temperature
of 25°C, a red fluid was formed with a separate dense
phase of tarry compounds. A 40-μL portion of the liquid
phase was dissolved in 1 mL of acetone and analyzed
by gas chromatography/mass spectrometry (GC/MS).
Additionally, FT-IR spectra were recorded. The tarry
compounds were analyzed by FT-IR spectroscopy and
UV-Vis spectrophotometry. Then, 3–5 mL of water was
added to the tarry compounds until a complete hydrolysis
occurred and a 3-fold extraction with 1 mL of n-hexane
was performed. The resulting extract was analyzed by
GC/MS.
yldecalines [3]. However, to raise the selectivity of the
corresponding reactions, it is necessary to use aluminum
chloride complexes containing ions of transition metals:
iron, nickel, cobalt, copper, etc. [4–6]. It is known that
iron-based complexes produced from metallic Fe and
CCl in acetonitrile and dimethylacetamide are active in
4
the telomerization of ethylene [7]. Of scientific interest
in this context is the in situ formation in the reaction
medium of aluminum chloride complexes containing
ions of transition metals from the corresponding alloys
and organochlorine compounds, among which tert-butyl
chloride (TBC) has gained wide acceptance.
The goal of our study was to examine the reactivity of
theAl/Fe alloy with respect to organochlorine compounds
for producing in situ catalytic (Fe-,Al/Cl) complexes from
the systems Al/Fe/TBC and Al/Fe/TBC in n-hexane and
(b) A 5 × 5 mm 0.1-g alloy sample with a thickness
of 2.0 m was placed in a Teflon reactor of special design
that enabled delivery of gases, and then 10 mL of TBC
1
926

IN SITU FORMATION OF Al(Fe)/Cl METAL CHLORIDE COMPLEXES
1927
was added. Helium was delivered into the reactor under a
pressure of 0.2–0.4 MPa. The reaction mixture was kept
in a thermostat at 80°C for 6–7 h. The reaction products
were analyzed as noted above.
deuterated triglycine sulfate detector in the spectral range
–
1
–1
7400–400 cm with resolution of 4 cm . ATR-FT-IR
spectra were obtained on the same instrument with an
additional special attachment. A ZnSe crystal served as
the internal reflection element.
(
c) An alloy sample with mass of 0.1–1.15 g,
dimensions of 5 × 7 mm, and thickness of 1.8–2.0 mm was
placed in a Teflon reactor of special design that enabled
delivery of gases, and then a 4-fold excess of TBC and
UV-Vis absorption spectra were obtained with a
Shimadzu UV 2501PC spectrophotometer at 190–900 nm.
The UV-Vis spectrum of the cuvette was subtracted from
these spectra.
15 mLof n-hexane were added. Helium was delivered into
the reactor under a pressure of 0.2–0.4 MPa. The reaction
mixture was kept in a thermostat at 80°C for 9–10 h. The
alloy sample did not react completely: the conversion of
the alloy was only 1.91%. The reaction alloy was partly
covered by a layer of raspberry-red products, which
confirms that compounds of unknown composition are
formed and hinder further dissolution of the alloy. The
GC/MS method was used to analyze the liquid phase.
RESULTS AND DISCUSSION
After a prolonged (~20 h) interaction of theAl/Fe alloy
2.15 wt %) with TBC at 25°C, release of tarry compounds
and a change in the coloration of the liquid reaction
mixture were observed. The FT-IR spectrum of the tarry
reaction products demonstrated in the low-frequency
spectral range a strong absorption band at 493 cm–1
(
(
Fig. 1, spectrum 1). According to published data, this
Reaction of Ethylene Oligomerization
band is associated with stretching vibrations of Al–Cl
bonds in the tetrahedral ion AlCl4 [9, 10]. Additionally,
the FT-IR spectrum exhibited absorption bands at 523
and 608 cm , associated with stretching vibrations of the
Al–Cl bonds in the binuclear ion Al Cl and molecular
formAlCl , respectively [11, 12]. In addition, absorption
bands at 2730 and 2414 cm were recorded in the FT-IR
spectrum, these bands being associated with stretching
vibrations of H–Cl bond in hydrogen chloride molecules
interacting with aluminum chloride complexes and
olefins, respectively [13, 14]. The absorption band at
–
a) Ethylene was passed at a flow rate of 1 mL min–1
(
for 1 h under a pressure of 0.11–0.12 MPa at a temperature
of 15°C through metal chloride complexes formed in situ
by procedure (a). The reaction products were analyzed
by the GC/MS method.
–1
–
7
2
3
–
1
(
b) A 0.1–0.15-g portion of an Al/Fe alloy (2.15 wt %
Fe) was placed in a Teflon reactor of special design,
0 mL of TBC was added, and ethylene was delivered to
create an excess pressure of 0.2–0.4 MPa. The reaction
mixture was kept in a thermostat for 80°C for 7–8 h and
then cooled and analyzed.
1
–
1
1
644 cm corresponds to the frequency of stretching
vibrations of C=C bonds in olefins.
(
c) Ethylene was added under an excess pressure of
The qualitative composition of aluminum chloride
complexes formed in situ in the interaction of the Al/Fe
alloy (2.15 wt %) with TBC at 80°C is not changed sig-
nificantly (Fig. 1, spectrum 2). However, the appearance
of an absorption band was recorded in the FT-IR spectrum
0
.2–0.4 MPa to metal chloride complexes formed in situ
by procedure (c) (in hexane). The reaction mixture was
kept in a thermostat at a temperature of 80°C for 1 h.
Liquid reaction products were analyzed by GC/MS, and
tarry compounds formed on the alloy plate were scraped
off with a putty knife and analyzed by multiple attenuated
total reflectance FT-IR (ATR-FT-IR) spectroscopy.
–1
at 1601 cm , this band being characteristic of vibrations
of C=C bonds in dienes and polyenes.
Figure 2 shows UV-Vis spectra of the tarry compounds
formed in the reactions at 25 and 80°C. A strong
absorption is recorded in the spectral range 220–400 nm.
According to the available published data, the absorption
The composition of the products being formed was
analyzed by gas chromatography/mass spectrometry on
a 6890/5973N instrument (Agilent Technologies) with a
mass spectrometer of the quadrupole type with ionization
energy of 70 eV.
2+
band at 334 nm is due to the electron transitions in FeCl
ions [15], and the absorption bands at 307 and 388 nm, to
3
+
To obtain FT-IR and UV-Vis spectra, a demountable
cell with 0.015-mm-thick absorbing layer and KBr glasses
was used. FT-IR absorption spectra were obtained on a
NICOLET 5700 Fourier-transform IR spectrometer with a
transitions in Fe ions [16]. Additionally, the spectrum
shows π → π* electron transitions in polyenes.
An analysis of hydrolyzed tarry reaction products
by the GC/MS method demonstrated the presence of a
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 90 No. 12 2017

1928
ARBUZOV et al.
Fraction composition of ethylene conversion products obtained on different catalytic systems
Fraction composition, mol %
Catalytic system
olefins
chloroalkanes
hydrocarbons
С9+
С4
С6
С8
С6
С8
С , С
5
7
Al/Fe/TBC alloy (procedure a)
Al/Fe/TBC alloy (procedure b)
Al/Fe/TBC alloy (procedure c)
4.3
1.4
–
–
–
–
–
–
–
–
25.2
9.2
–
4.6
13.8
–
22.9
5.8
–
43.0
69.8
–
70.6
29.4
wide variety of cyclopenta-1,3-diene and cyclohexa-1,3-
diene derivatives. The liquid reaction products are for
the most part represented by 2,2,4-trimethylpentane and
organochlorine compounds: 2-chloro-2-methylbutane,
2
-chloro-2,3-dimethylbutane, and 2-chloro-2,5,5-
trimethylhexane.
Table 1 presents the results of catalytic tests of the
oligomerization of ethylene. It can be seen that oligomers
are predominantly formed in the liquid reaction medium
on catalytic complexes produced in situ from the Al/Fe
alloy (2.15 wt %) and TBC in n-hexane. In the absence
of this solvent, chloroalkanes are predominantly formed
in the liquid reaction medium, which is possibly due to
the occurrence of reactions in which ethylene oligomers
are hydrochlorinated. The GC/MS revealed in the tarry
reaction products cyclopenta-1,3-diene and cyclohexa-
ν, cm–1
Fig. 1. FT-IR spectra of aluminum chloride complexes formed
in situ by procedure (1) a and (2) b. (A)Absorption and (ν) wave
number.
1,3-diene derivatives with molecular masses of up to
–1
388 g mol , which indicates that there occurs the coupled
oligomerization reaction.
ν, cm–1
λ, nm
Fig. 3. ATR-FT-IR spectra of the catalytic system Al/Fe/TBC
alloy in n-hexane, produced by procedure c under the conditions
of the ethylene oligomerization reaction. (A) Absorption and
(ν) wave number.
Fig. 2. UV-Vis spectra of Fe/Cl complexes formed in situ by
procedure (1) a and (2) b. (A) Absorption and (λ) wavelength.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 90 No. 12 2017

IN SITU FORMATION OF Al(Fe)/Cl METAL CHLORIDE COMPLEXES
1929
ν, cm–1
λ, nm
Fig. 5. FT-IR absorption spectra of aluminum chloride
Fig. 4. UV-Vis absorption spectrum of a Fe/Cl complex formed
in situ by procedure a, under the conditions of the reactions of
coupled ethylene oligomerization and hydrochlorination of
olefins. (A) Absorption and (λ) wavelength.
complexes formed in situ by procedure (1) a and (2) b under the
conditions of the reactions of coupled ethylene oligomerization
and hydrochlorination of olefins. (A) Absorption and (ν) wave
number.
Figure 3 shows ATR-FT-IR spectra of aluminum
chloride complexes produced in situ under the conditions
of the ethylene oligomerization reaction. Together with
of the type AlCl /olefin are necessary for the reaction of
ethylene oligomerization to occur.
3
–
–1
the absorption bands of the Al Cl ion (527 cm ),
CONCLUSIONS
2
7
–
1
there appear new absorption bands at 501 and 580 cm ,
characteristic of stretching vibrations of Al–Cl bonds in
the AlCl4– ions with C3v symmetry [17]. Additionally,
the ATR-FT-IR spectrum exhibited absorption bands
(1) According to FT-IR and UV-Vis spectroscopic
data, the interaction of the Al/Fe alloy (2.15 wt %)
with tert-butyl chloride yields in situ ion complexes of
–
–
+
–
1
composition AlCl ,Al Cl , and FeCl , Fe3+ ions and
at 554 and 604 cm , which are presumably associated
with stretching vibrations of Al–Cl bonds in molecular
4
2
7
2
molecular form AlCl3.
complexes of the type AlCl /olefin [18].
(2)ATR-FT-IR spectroscopy demonstrated thatAlCl3/
ethylene molecular complexes are necessary for the
reaction of ethylene oligomerization to occur.
3
In the conditions of the reactions of coupled oligo-
merization and hydrochlorination of olefins, the main
changes were observed by UV-Vis spectroscopy in the
spectral range 250–400 nm (Fig. 4). For example, an
increase was recorded in the intensity of the absorption
bands at 303 and 386 nm, associated with electron transi-
ACKNOWLEDGMENTS
The study was carried out on the equipment of Omsk
Regional Collective Use Center, Siberian Branch, Russian
Academy of Sciences.
3+
2+
tions in Fe ions. It can be assumed that both FeCl and
3+
Fe ions are involved in the transformations of ethylene.
According to FT-IR spectroscopic data, the qualitative
composition of aluminum chloride complexes produced
in situ is not changed significantly in the reactions of
coupled oligomerization and hydrochlorination of olefins
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