Selective dimerization of ethylene to but-1-ene under the conditions of industrial process. II. Selection of a solvent for the process of ethylene to but-1-ene dimerization

Article abstract of DOI:10.1134/S1070427207070397

A comparative economical analysis of reasons for application the solvents of various type in the process of ethylene to but-1-ene dimerization and of technological schemes of rectification of the products of ethylene dimerization with use of different solvents. The optimal solvent for the currently working industrial process of ethylene to but-1-ene dimerization is hexane fraction forming in the process of ethylene dimerization.

Full text of DOI:10.1134/S1070427207070397

ISSN 1070-4280, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 7, pp. 1201–1206. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © V.I. Zhukov, G.V. Val’kovich, B.N. Skorik, Yu.M. Petrov, G.P. Belov, 2007, published in Khimicheskaya Promyshlennost’, 2007,
Vol. 84, No. 1, pp. 1–7.
TECHNOLOGY OF ORGANIC
AND INORGANIC SUBSTANCES
Selective Dimerization of Ethylene to But-1-ene under
the Conditions of Industrial Process.
II. Selection of a Solvent for the Process of Ethylene
to But-1-ene Dimerization
V. I. Zhukova, G. V. Val’kovicha, B. N. Skorika, Yu. M. Petrova, and G. P. Belovb
aLukoil-Neftekhim Group, Stavrolen Co., Budenovsk, Russia
bInstitute of Probems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Russia
e-mail: gbelov@cat.icp.ac.ru
Received February 5, 2007
Abstract—A comparative economical analysis of reasons for application the solvents of various type in the process
of ethylene to but-1-ene dimerization and of technological schemes of rectification of the products of ethylene
dimerization with use of different solvents. The optimal solvent for the currently working industrial process of eth-
ylene to but-1-ene dimerization is hexane fraction forming in the process of ethylene dimerization.
DOI: 10.1134/S1070427207070397
The highly selective process of manufacturing but-
1-ene by catalytic dimerization of ethylene has been
first developed in the Institute of Problems of Chemi-
cal Physics RAS and in cooperation with joint-stock
companies Stavrolen and Kazanorgsynthes realized in
industry [1–3]. In [4] we performed analysis of mass
and heat balances of the reaction node for the process
of ethylene dimerization under industrial conditions.
The process of ethylene dimerization is performed
with homogenous catalyst Ti(OR)4 – AlR|3 – modifica-
tor in the medium of hydrocarbon solvent. As the sol-
vent can be used individual or mixed hydrocarbons,
including the products of dimerization.
with the catalyst components and the catalyst
whole,
–should have certain composition on hydrocarbons
providing stable proceeding of the process in
time,
–should provide simple by technology method of
separation of the dimerization products,
–should be accessible, accepted in the industrial
scale and advantageous economically.
Taking into account these requirements, investiga-
tions for evaluation of various solvents and selecting
the perfect one have been conducted.
Among the solvents for the ethylene to but-1-ene
dimerization could be used the following solvents:
–individual paraffin hydrocarbons (hexane, hep-
tane and others and their mixtures),
The solvent in the process of dimerization bears
several functions:
–as a reaction medium for the process,
–solving ethylene and dimerization products,
–maintaining required temperature regime,
–promoting heat withdraw.
–naphthene solvents (cyclohexane),
–aromatic solvents (benzene, toluene and others),
–unsaturated hydrocarbons (but-1-ene, hexenes),
–halohydrocarbons (chloroethane, bromoethane),
–ethers (diethyl, diisopentyl),
In this connection, the solvent should obey the fol-
lowing requirements:
–it should be chemically inert to the catalyst com-
ponents, monomer and dimerization products,
–should contain minimum admixtures reacting
–industrial hydrocarbon fractions C6 or C7 (Nefras
“A”, Nefras “C”, BR-1, BR-2 and others).
In [5] was reported that the solvent nature affects
1201

1202
ZHUKOV et al.
activity and selectivity of the process and increases
them in the order: aromatic hydrocarbons; naphthene,
paraffin hydrocarbons and industrial hydrocarbon frac-
tions; chlorinated hydrocarbons, unsaturated hydrocar-
bons, ethers. This order can vary with increase in the
process temperature.
From the viewpoint of the catalyst discharge, use
of ethers as the solvent is disadvantageous due to en-
hanced consumption of organoaluminum component
owing to necessity in higher AlR’3/Ti(OR)4 ratio, up to
(10–20):1 instead of (4–3):1 in all other cases, ex-
plained by their chemical interaction with formation of
strong AlR3·R2O complex. The cost of halohydrocar-
bons such as bromoethane or chloroethane is too high
and therefore their application is also unreasonable.
The most accessible solvents produced industrially
are Nefras “A” 65/75 and Nefras “C” 94/99, and but-1-
ene and hexenes formed in the process of ethylene
dimerization as well. Estimating all the abovesaid, we
have analyzed for the industrial application the possi-
bility of use of hydrocarbon solvents of Nefras type,
isopentane, and hexanes forming in the process of
dmerization, and their mixtures.
Fig. 1. Scheme of separation of the products of ethylene
dimerization with Nefras “A” 65/75 as a solvent.
Certain choice can be made after comparison of
various schemes for isolation of but-1-ene, hexenes
and polymer. The choice becomes the simplest when
technological scheme of separation of the products of
dimerization is analyzed.
ANALYSIS OF THECNOLOGICAL SCHEMES
FOR THE SEPARATION OF THE PRODUCTS
OF DIMERIZATION
In the process of ethylene dimerization various
olefins are formed: but-1-ene, but-2-ene, hexenes (hex-
Fig. 2. Scheme of separation of the products of ethylene
dimerization with Nefras “C” 94/99 as a solvent.
Table 1. Boiling points of solvents and hexanes
No.
1
Solvent or hexane component
Nefras “A”
Boiling point or boiling temperature range
65–75
94–99
54.2
2
Nefras “C”
3
3-Methylpent-1-ene
2-Ethylbut-1-ene
Hex-1-ene
4
64.6
5
63.4
6
Isopentane
27.8
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SELECTIVE DIMERIZATION OF ETHYLENE TO BUT-1-ENE. II.
1203
1-ene 10%, 3-methylpent-1-ene 30%, 2-ethylbut-1-ene
60% of the sum of hexenes), little amounts of oli-
gomers (C8 and higher) and of polymer (less than 0.5
weight %). The fraction of each component depends
on the process conditions and catalytic system. Be-
sides, the reaction mixture contains dissolved ethylene,
the solvent selected for the process and (when triisobu-
tylaluminum is used as a component of catalytic sys-
tem) certain amounts of isobutene and isobutylene.
In the further analysis of various technological
Table 2. Operating parameters of the column for separation ethylene and C4 fraction
No.
1
Parameter or characteristic
Operating pressure
Units
kg/cm2
ºC
Value
4–10
2
Column top temperature
20–40
3
4
5
6
Column bottom temperature
Column efficiency
ºC
130–150
Ntp*
wt %
wt %
12
Column top composition
Column bottom composition
ethylene 3.0, but-1-ene 96.0, n-butane 1.0
Solvent 53.3, hexenes 38.2, oligomers 2.0,
butene up to 2.5
Ntp* - Number of theoretical plates
Table 3. Operating characteristics of the column for ethylene separation
No.
Parameter or characteristic
Units
Value
1
2
3
Operating pressure
kg/cm2
ºC
4–8
Column top temperature
Column bottom temperature
25–30
40–60
ºC
4
5
6
Column efficiency
Column top composition
Column bottom composition
Ntp*
wt %
wt %
10
ethylene 50, but-1-ene 50
but-1-ne 99.5, n-butane 0.2, but-2-ene 0.3
Table 4. Operating characteristics of the column for Nefras “A” 65/75 and hexenes separation from oligomers
No
1
Parameter or characteristic
Operating pressure
Units
kg/cm2
ºC
Value
0.1–0.2
70–80
2
Column top temperature
Column bottom temperature
3
ºC
130–150
4
5
6
Column efficiency
Column top composition
Column bottom composition
Ntp*
wt %
wt %
33
Nefras “A” 45.5, but-1-ene 4.0
Hexenes 40.0, Nefras 50.0, oligomers 10.0
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ZHUKOV et al.
schemes we omit separation into components of C4
fraction, which composition is controlled by the
dimerization process.
Depending on the nature of the chosen solvent, the
principal technological schemes of rectification appear
as seen in Figs. 1–5. As seen from the schemes, when
Nefras “A” 65/75 is taken as a solvent in the ethylene
dimerization, it can not be separated from the forming
hexenes due to closeness of their boiling temperatures
(Table 1, Fig. 1).
Application of Nefras “C” 94/99 allows isolation
of hexenes, but additional column should be installed
for its separation from oligomers (Fig. 2).
The most rational scheme is seems which uses
hexenes (Fig. 3) or isopentane (Fig. 4) as a solvent. In
these cases individual 3-methylpent-1-ene and 2-
ethylbut-1-ene with hexane admixture can be isolated
(Fig. 5).
Fig. 3. Scheme of separation of the products of ethylene
dimerization with hexenesas a solvent.
For the drying reaction node and separation nodes,
a node for azeotropic drying of solvent is needed; its
principal scheme is shown in Fig. 6.
The drying node can operate continuously or in
periodical regime.
All the schemes include first a column for separa-
tion of ethylene and C4 fraction. Its characteristics are
listed in Table 3. The characteristics of the column for
separation Nefras “A” 65/75 and hexenes from oli-
gomers are listed in Table 4, for Nefras “C” 94/99 in
Table 5. The characteristics of the column for separa-
tion of hexenes from Nefras “C” are given in Table 6.
For separation of 3-methylpent-1-ene and 2-
ethylbut-1-ene is used a column which characteristics
Fig. 4. Scheme of separation of the products of ethylene
dimerization with isopentane as a solvent.
Fig. 5. Principal technological scheme for separation of
Fig. 6. Principal technological scheme for drying the
hexenes.
solvent.
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SELECTIVE DIMERIZATION OF ETHYLENE TO BUT-1-ENE. II.
1205
Table 5. Operating characteristics of the column for Nefras “C” 94/99 and hexenes separation from oligomers
No.
1
Parameter or characteristic
Operating pressure
Units
kg/cm2
ºC
Value
No more than 0.5
100–110
2
Column top temperature
Column bottom temperature
3
ºC
130–150
4
5
6
Column efficiency
Column top composition
Column bottom composition
Ntp*
wt %
-“-
33
Nefras “C” 100%
Nefras ”C” 98.0, oligomers 2.0
Table 6. Operating characteristics of the column for hexenes separation from Nefras “C”
No.
1
Parameter or characteristic
Operating pressure
Units
kg/cm2
ºC
Value
No more than 0.5
70–80
2
Column top temperature
Column bottom temperature
3
ºC
125–135
4
5
6
Column efficiency
Column top composition
Column bottom composition
Ntp*
wt %
wt %
28
Hexenes 80.3, but-1-ene 4.4, Nefras “C” 15.3
Nefras “C” 98.5, oligomers 1.5
Table 7. Operating characteristics of the column for separation of 3-methylpent-1-ene and 2-ethylbut-1-ene
No.
Parameter or characteristic
Units
Value
1
2
3
Operating pressure
kg/cm2
ºC
No more than 0.5
60–70
Column top temperature
Column bottom temperature
ºC
70–80
4
5
6
Column efficiency
Column top composition
Column bottom composition
Ntp*
wt %
wt %
35
3-methylpent-1-ene 95.0, 2-ethylbut-1-ene 5.0
2-ethybut-1-ene 85.0, 3-methylpent-1-ene 5.0,
hex-1-ene 10.0
are listed in Table 7. The characteristics of the column
for separation of hexenes from oligomers are listed in
rerererre Table 9 lists characteristics of the column for
azeotropic solvent drying.
Thus, consideration of technological schemes of
rectification at the application of various solvents al-
lows to select two type of solvents for the process of
ethylene to but-1-ene dimerization:
RUSSIAN JOURNAL OF APPLIED CHEMISTRYVol. 80 No. 7 2007

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ZHUKOV et al.
Table 8. Operating characteristics of the column for separation of hexanes from oligomers
No.
1
Parameter or characteristic
Operating pressure
Units
kg/cm2
ºC
Value
No more than 0.5
70–80
2
Column top temperature
3
Column bottom temperature
ºC
130–150
4
5
6
Column efficiency
Column top composition
Column bottom composition
Ntp*
wt %
wt %
33
hexenes 100%
hexenes 98.9, oligomers up to 2.0
Table 9. Operating characteristics of the column for azeotropic drying of solvent
No.
1
Parameter or characteristic
Operating pressure
Units
kg/cm2
ºC
Value
No more than 0.7
95–100
2
Column top temperature
Column bottom temperature
3
ºC
105–110
4
5
6
Column efficiency
Column top composition
Column bottom composition
Ntp*
wt %
wt %
12
solvent 99.9, water (steam condensate) 0.1
solvent 100.0
Plasticheskie Massy, 1990, vol. 10, p. 82.
–those forming hexenes in the process of dimeri-
2. Zhukov, V.I., Belov, G.P., Germashev, A.I., and Saush-
kin, Yu.I., Plasticheskie Massy, 1996, no. 5, p. 6.
3. Belov, G.P., Borodin, A.M., Val’kovich, G.V., Zhu-
kov, V.I., Polevshchikov, N.P., Petrov, Yu.M., and
Skorik, I.N., Summa Technologii (Review of Russian
Technologies), 2001, no. 1, p. 79.
4. Zhukov, V.I., Val’kovich, G.V., Skorik, B.N., Petrov,
Yu.M., and Belov, G.P., Khim. Promyslennost’, 2005,
vol. 82, no. 8, p. 382.
5. Belov, G.P., Kinetika protsessov dimerizatsii i polimeri-
zatsii etilena pod deistviem Ti-soderzhashchikh kataliza-
torov i svoistva obrazuyushchikhsya produktov (Kinetics
of ethylene dimerization and polymerization with Ti-
containing catalysts and properties of the products
formed). Doctorate dissertation, chemistry, Moscow:
Inst. Khim. Fiziki RAN, 1984.
zation
–isopentane.
Use of hexenes rather than isopentane is economi-
cally advantageous because the hexenes formed in the
process of ethylene dimerization after their separation
from but-1-ene do not require any drying to remove
water or purification for removing other admixtures
which could partially deactivate the catalyst.
REFERENCES
1. Ivanchev, S.S., Zhukov, V.I., Belov, G.P., Ivolgina, S.R,
Germashev, A.I., Gabutdinov, M.S., and Shestak, N.P.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 7 2007