Kinetics and products distribution of selective catalytic hydration of ethylene- and propylene oxides in concentrated aqueous solutions

Article abstract of DOI:10.1021/op010099+

The kinetics of selective hydration of ethylene- and propylene oxides in concentrated aqueous solutions is studied during homogeneous catalysis by sodium bicarbonate. The mathematical model of the process with determined parameters adequately describing the rate of the reaction and products distribution is developed.

Full text of DOI:10.1021/op010099+

Organic Process Research & Development 2002, 6, 660−664
Kinetics and Products Distribution of Selective Catalytic Hydration of Ethylene-
and Propylene Oxides in Concentrated Aqueous Solutions
I. A. Kozlovsky, R. A. Kozlovsky,* A. V. Koustov, M. G. Makarov, J. P. Suchkov, and V. F. Shvets
D.I.MendeleeV UniVersity of Chemical Technology of Russia, Chair of Basic Organic and Petrochemical Synthesis,
9
Miusskaya Square, Moscow 125047, Russia
and metalate anions.7 The kinetics and reaction mechanism
-8
Abstract:
The kinetics of selective hydration of ethylene- and propylene
oxides in concentrated aqueous solutions is studied during
homogeneous catalysis by sodium bicarbonate. The mathemati-
cal model of the process with determined parameters adequately
describing the rate of the reaction and products distribution is
developed.
of the hydration of R-oxides using homogeneous catalysis
3
,10,11
by salts have been explicitly studied.
obtained have shown that at a concentration of some salts
of about 0.5 mol/L the distribution factor b ) k /k is reduced
The kinetic data
1
0
10-fold more (to 0.1-0.2). This enables the production of
monoglycol with high selectivity at water/oxide molar ratios
close to 1. We have used hereinafter homogeneous nucleo-
philic catalysts with the above-mentioned properties for the
creation of industrial heterogeneous catalysts of a selective
hydration of ethylene- and propylene oxides by means of
an immobilization of anions of salts on heterogeneous
Introduction
The reaction of ethylene- and propylene oxides hydration
is an industrial way of obtaining of glycols, in particular
ethylene glycolsone of the most-produced large-scale
products of industrial organic synthesis, with the world
12-17
18-24
carriers.
The largest ethylene glycol producers Shell,
(4) Masuda, T. Production of polygydric alcohol. (Mitsui Toatsu Chem Inc.).
JP 61-271229, 1986.
1
annual production in 2000 of about 15.3 million t/year. The
(5) Masuda, T. Production of polygydric alcohol. (Mitsui Toatsu Chem Inc.).
oxide hydration reaction proceeds on a serial-to-parallel route
with a formation of homologues of glycol:
JP 61-271230, 1986.
(6) Masuda, T.; Asano, K. H.; Naomi, A. S. Method for preparing ethylene
glycol and/or propylene glycol. (Mitsui Toatsu Chem Inc.). EP 0226799,
1
992; U.S. Patent 4,937,393, 1990.
C H O
C H O
2 4
2
4
(7) Keen, B. T. Carbon dioxide-enhanced monoalkylene glycol production.
(Union Carbide Corp.). U.S. Patent 4,578,524, 1985.
(8) Keen, B. T.; Robson, J. H. Continuous process for the production of alkylene
glycol in the presence of organometalate. (Union Carbide Corp.). U.S. Patent
H O
8 HOCH CH OH
8
2
2
2
k0
k1
C H O
2
4
4,571,440, 1986.
HO(CH CH O) H
8 etc. (I)
2
2
2
k2
(9) Odanaka H.; Yamamoto T.; Kumazawa T. Preoparation of high-purity
alcylene glycol. (Nippon Shokubai Kagaku Kogyo Co. Ltd.). JP Patent
5
6-090029, 1981.
(10) Lebedev N. N.; Shvets V. F.; Romashkina L. L. Kinetics Catal. (Russ.)
976, 17(3), 583.
where k
0
, k , k are the rate constants of the series stages.
1 2
1
Presently, all ethylene- and propylene glycol is produced
in industry by a noncatalyzed reaction. Product distribution
in the reaction I is regulated by the oxide-to-water ratio in
the initial reaction mixture. The ratio of rate constants for
the stages of reaction I is unfavorable for monoglycol
formation (the distribution factor b ) k /k for a noncatalyzed
1 0
reaction of ethylene oxide with water according to different
data sources gives value 1.9-2.8 ). For this reason consider-
(
(
(
(
11) Lebedev N. N.; Shvets V. F.; Romashkina L. L. Kinetics Catal. (Russ.)
1976, 17(4), 888.
12) Shvets V. F.; Makarov M. G.; Suchkov J. P.; et al. Method for obtaining
alkylene glycols. (Vega Chemical Co. Ltd.). RU Patent 2001901, 1993.
13) Shvets V. F.; Makarov M. G.; Suchkov J. P.; et al. Method for obtaining
alkylene glycols. (Vega Chemical Co. Ltd.). RU Patent 2002726, 1993.
14) Shvets V. F.; Makarov M. G.; Koustov A. V.; Kozlovsky, I. A.; Kozlovsky,
R. A.; Suchkov, J. P. Process for obtaining alkylene glycols. WO 9733850,
1997.
2
(15) Shvets V. F.; Makarov M. G.; Koustov A. V.; Kozlovsky, I. A.; Kozlovsky,
R. A.; Suchkov, J. P. Method for obtaining alkylene glycols. RU Patent
able excess of water (molarity up to 20×) is applied to
increase the monoglycol yield in industry. This results in a
considerable power cost at the final stage of product isolation
from dilute aqueous solutions.
2
122995, 1999.
(
16) Shvets V. F.; Makarov M. G.; Koustov A. V.; Kozlovsky, I. A.; Kozlovsky,
R. A.; Suchkov, J. P. Method for producing alkylene glycols. WO 9912876,
1999.
(17) Shvets V. F.; Makarov M. G.; Koustov A. V.; Kozlovsky, I. A.; Kozlovsky,
R. A.; Suchkov, J. P. Method for obtaining alkylene glycols. RU Patent
One of the ways of increasing the monoglycol selectivity
and, therefore, of decreasing water excess is the application
of catalysts to accelerate only the first stage of the reaction
2149864, 2000.
(18) Reman W. G.; Van Kruchten, E. M. G. Process for the preparation of
alkylene glycols. (Shell Oil Co.). U.S. Patent 5,488,184, 1996.
(
19) Van Kruchten, E. M. G. Process for the preparation of alkylene glycols.
Shell Oil Co.). U.S. Patent 5,874,653, 1999.
3
-6
I. Such catalysts are the anions of salts of some acids
(
(20) Van Kruchten, E. M. G. Catalytic hydrolysis of alkylene oxides. (Shell
Oil Co.). WO 9923053, 1999.
*
To whom correspondence should be addressed. E-mail: (R.A.K.)
kra@muctr.edu.ru; (V.F.S.) shvets@muctr.edu.ru.
(21) Van Kruchten, E. M. G. Quaternary phosphonium salt catalyst in catalytic
hydrolysis of alkylene oxides. (Shell Oil Co.). WO 0035840, 2000.
(22) Van Kruchten, E. M. G. Carboxylates in catalytic hydrolysis of alkylene
oxides. (Shell Oil Co.). WO 0035842, 2000.
(23) Kunin R.; Lemanski M. F.; Van Kruchten, E. M. G. Catalyst stabilising
additive in the hydrolysis of alkylene oxides. (Shell Oil Co.). WO 0035841,
2000.
(
(
(
1) Noor-Drugan, N. Testing Times for Ethylene Glycol Makers. Chem. Week
1
999, March 3, 32.
2) Dyment O. N.; Kazansky K. S.; Miroshnikov A. M. Glycols and Their
DeriVatiVes (Russ.) Moscow, 1976.
3) Lebedev N. N.; Shvets V. F.; Romashkina L. L. Kinetics Catal. (Russ.)
1
976, 17(3), 576.
6
60
•
Vol. 6, No. 5, 2002 / Organic Process Research & Development
10.1021/op010099+ CCC: $22.00 © 2002 American Chemical Society
Published on Web 07/20/2002

Dow,25,26 BASF, Union Carbide,28-30and Mitsubishi con-
duct researches on the elaboration of selective catalysts of
ethylene oxide hydration in the same direction.
27
31
The Kinetic Model. The mechanism of the catalysis of
R-oxides hydration by anions consists of the nucleophilic
-
In concentrated aqueous solutions of glycols it is necessary
to take into account that the oxide is solvated in equilibrium
II not only by water, but also by glycols. Having designated
the effective concentration of proton donor materials activat-
ing an oxide cycle through a hydrogen bond formation by
addition of anion (A ) of the catalyst to a solvated molecule
8
-10
of R-oxide:
33
[SH], we obtain:
[
SH] ) [H O] + p
∑[Glyi]
(2)
2
i
where Σ[Gly ] is the sum of the concentrations of monoglycol
and all polyglycols obtained by reaction I; p is the parameter
describing the efficiency of R-oxide solvation by glycols
relative to water.
Supposing, that the equilibrium II is established quickly
and is shifted to the left, eq 1 for concentrated glycol
solutions can be presented by the equation:
and subsequent hydrolysis of an intermediate ester with the
formation of glycol and regeneration of the catalyst:
-
r ) k [A ][C H O][SH]
(3)
ct
2
4
-
-
Taking into account the parallel noncatalyzed reactions
of R-oxide (reaction I) proceeding according to the mech-
anism (V, VI), we obtain a general kinetic equation of
R-oxide consumption in concentrated solutions at a nucleo-
philic catalysis:
AOCHCHOH + HO f A + HOCH CH OH (IV)
2
2
The rate-determining stage in most cases is the formation
of an intermediate ester by reaction III, and in dilute aqueous
solutions the rate of the reaction is described by the following
4
kinetic equation:
-
-
d[C H O]/dt ) (k ([H O] + bΣ[Gly ]) + k [A ])([H O] +
2
4
0
2
i
ct
2
-
r ) k[C H O][A ]
(1)
pΣ[Gly
i
])[C
2
H
4
O] (4)
2
4
2
In the derivation of eq 4 it was also assumed that the
rate constants of series stages of the reaction I after the first
) are equal, that is
b ) k /k ) k /k ) k /k ) ...
The kinetic model of reaction III, suitable for the
quantitative description of the heterogeneous catalytic process
in a wide range of concentrations of water and glycol is
indispensable for the implementation of the industrial
catalytic process of the hydration of concentrated water
solutions of R-oxide. The kinetic experiments conducted by
us have shown that the immobilization of anions on ion-
exchange resin does not change selectivity, the kinetic
equation, or its parameters. It gives the basis to use the results
of experiments on a homogeneous catalytic hydration for
obtaining the demanded model. Let’s deduce such a model
on the basis of a trimolecular mechanism of an oxide ring-
opening (II, III), which is also valid for a noncatalyzed
reaction of an R-oxide hydration:
(k
0
1
0
2
0
3
0
The determination of the parameters of the eq 4 was
conducted for a homogeneous catalysis using a bicarbonate
ion, one of the most actiVe and accessible nucleophilic
catalysts of R-oxide hydration.
Experimental Section
3
Materials. NaHCO , ethylene glycol, diethylene glycol,
triethylene glycol, and propylene glycol were purchased from
commercial suppliers and used without further purification.
Ethylene oxide and propylene oxide were purified by
distillation under solid NaOH. Water was purified by
distillation.
(
28) Soo, H.; Ream, B. C.; Robson, J. H. Monoalkylene glycol production using
mixed metal framework compositions. (Union Carbide Chem. Plastic). U.S.
Patent 4,967,018, 1990.
and reaction of polyglycols formation:32
(
29) Soo H.; Ream B. C.; Robson J. H. Mixed metal framework compositions
for monoalkylene glycol production. (Union Carbide Chem. Plastic). U.S.
Patent 5,064,804, 1990.
(
(
(
24) Van Kruchten, E. G. A. Catalytic hydrolysis of alkylene oxides. (Shell Oil
Co.). U.S. Patent 6,137,014, 2000.
(30) Forkner, M. W. Monoalkylene glycol production using highly selective
monoalkylene glycol catalysts. (Union Carbide Chem. Plastic). U.S. Patent
5,260,495, 1993.
(31) Iwakura, T.; Miyagi, H. Production of alkylene glycol. (Mitsubishi Chemical
Corp.). JP Patent 11012206, 1999.
25) Lee, G.-S. J.; Rievert, W. J.; Landon Von, G.; Strickler, G. R. Process for
the production of ethelene glycol. (Dow Chemical Co.). WO 9931033, 1999.
26) Lee, G.-S. J.; Rievert, W. J.; Landon Von, G.; Strickler, G. R. A method
for making glycol in an adiabatic reaction system. (Dow Chemical Co.).
WO9931034, 1999.
(32) Lebedev, N. N.; Savelyanov, V. P.; Baranov, J. I.; Shvets, V. F. J. Org.
Chem. (Russ.) 1969, 5, 1542.
(27) Gehrer, E.; Stein, B.; Grosch, G. Production of alkylene glycol by reacting
alkylene oxide with water on a catalyst. (BASF AG). German Patent DE
(33) Makarov, M. G.; Guskov, A. K.; Shvets, V. F. J. Phys. Chem. (Russ.)
1982, 56, 1, 71.
1
9757684, 1999.
Vol. 6, No. 5, 2002 / Organic Process Research & Development
•
661

Table 1. Products distribution and monoglycol yields of a noncatalyzed reaction of ethylene- and propylene oxide hydration
calculated according to the eqs 6 and 7 and experimental values
monoglycol, % mass
diglycol, % mass
calc exp
triglycol, % mass
calc exp
monoglycol yields, %
â
calc
exp
calc
exp
Ethylene Oxide, First Six Points at 94 °C, the Rest at 90 °C, b ) 2.6 ( 0.1
0
0
0
0
0
0
0
0
0
0
.0454
.0722
.102
.136
.174
.22
.1
.2
.3
.4
12.57
17.74
22.11
25.74
28.49
30.58
21.84
29.82
32.09
31.86
12.27
17.0
1.21
2.65
4.56
6.88
9.44
-
-
-
-
-
-
0.065
0.22
0.52
1.03
1.76
2.85
0.49
2.35
5.04
7.97
-
-
-
-
-
-
89.3
83.9
78.6
73.1
67.8
62.1
78.9
64.4
53.8
45.7
87.2
80.4
76.1
68.8
63.3
57.0
78.5
70.5
59.0
50.2
21.4
24.2
26.6
28.1
12.4
4.41
11.2
16.83
20.98
21.74
32.63
35.20
35.02
3.38
0.292
10.87
16.09
21.91
2.04
4.16
7.83
Propylene Oxide, 94 °C, b ) 2.85 ( 0.13
0
0
0
0
0
0
0
0
.0253
.0601
.0848
.103
.13
.197
.217
.311
9.03
18.06
22.13
24.20
26.64
31.38
30.8
8.95
17.61
21.98
24.42
27.23
31.08
31.7
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
91.3
84.8
78.8
74.0
68.8
61.7
57.1
49.6
90.5
82.7
78.2
74.7
70.4
61.1
58.8
49.3
-
-
-
-
-
-
-
32.56
32.34
d[Gly ]/d[C H O])([H O] - b[Gly ])/([H O]+b([H O] -
Apparatus. The rate of the reaction was measured by
1
2
4
2
1
2
2
0
the pressure drop of ethylene or propylene oxide vapors over
[H O])) (6)
2
34
the reaction mixture using a manometer. The other experi-
ments were carried out in the isothermal batch autoclave,
equipped with an automatic temperature controller.
d[Gly ]/d[C H O])b([Gly ] - [Gly ])/([H O]+b([H O] -
i
2
4
i-1
i
2
2
0
[H O])) (7)
2
Analysis. The contents of mono-, di-, and triethylene
glycols and propylene glycol in the reaction products was
where [H
2
O]
0
) initial concentration of water, mol/L;
Gly ] ) [H O] - [H O]
-
3
determined by GLC, using a 1 m × 3 mm × 10 m glass
∑[
i
2
0
2
column packed with 15% FFAP on INERTON AW-DMCS
(0.2-2.25 mm). 2-Ethoxyethanol was used as an internal
The best correspondence of computed and experimental
values of product concentrations listed in the Table 1 is
obtained with b values of 2.6 ( 0.2 for the hydration of
ethylene oxide and 2.85 ( 0.13 for hydration of propylene
oxide.
For the determination of the other unknown parameters
of eq 4 a series of kinetic experiments with variation of the
concentrations of sodium bicarbonate, water, glycol, and
temperature was carried out. The initial concentrations of
ethylene or propylene oxides were within the limits 0.5-
standard.
Results and Discussion
During the first stage of the determination of the
parameters a series of experiments on the analysis of products
distribution in a noncatalyzed hydration of ethylene- and
propylene oxides was conducted to obtain a more precise
definition of the distribution factor b. The experiments were
conducted at an oxide/water molar ratio of â ) 0.045-0.4
in an autoclave at 90-94 °C up to full transformation of
oxide. The obtained yields are listed in the Table 1.
According to the eq 4 the rate of glycol and polyglycol
formation is described in the absence of the catalyst by the
equations:
1.0 mol/L, water concentrations in the glycol-water mixtures
were changed from 20 up to 80% of mass. Under these
conditions the first-order kinetics of ethylene or propylene
oxide consumption were observed:
r ) kexp[oxide]
-
d[Gly ]/dt ) k ([H O] - b[Gly ])([H O] +
1
0
2
1
2
p
[Gly ])[C H O] (5)
The experimental values of the first-order rate constants
were calculated as tangents of straight-line angles in coor-
dinates ln P - time, where P is partial pressure of ethylene
or propylene oxide. These experimental rate constants are
listed in Table 2. According to the eq 4 they can be
represented by:
∑
i
2
4
-
d[Gly ]/dt ) k b([Gly ] - [Gly ])([H O] +
i
0
i-1
i
2
p
[Gly ])[C H O]
i 2 4
∑
-
Having divided eq 5 by eq 4 at kct[A ] ) 0, we obtain
equations for the calculation of products distribution, pre-
sented in the Table 1:
-
3
kexp ) (k ([H O] + b [Gly ]) + k [HCO ])([H O] +
0
2
∑
i
ct
2
p∑
[Gly ]) (8)
i
(34) Lebedev, N. N.; Shvets, V. F. Kinetics Catal. (Russ.) 1968, 9, 504.
6
62 Vol. 6, No. 5, 2002 / Organic Process Research & Development
•

Table 2. Experimental (kexp) and calculated (kcalc) rate
Table 3. Experimental (kexp) and calculated (kcalc) rate
5
-1
5
-1
constants (× 10 s ) of ethylene oxide hydration
constants (× 10 s ) of propylene oxide hydration (in the
brackets there are catalyst concentrations which differ from
standard values)
temperature
7
0 °C
80 °C
90 °C
-], mol/L
HCO
3
[
[
HCO
3
-], mol/l
k
exp
k
calc
k
exp
k
calc
k
exp
k
calc
0
.0
0.1
0.3
0.5
Ethylene Glycol:Water Mass Ratio ) 0:1
T, °C
k
exp
k
calc
k
exp
k
calc
k
exp
k
calc
k
exp
k
calc
0
0
0
0
3.63
5.41
8.46
3.65
8.07
8.14 16.76 17.39
.1
.3
.5
5.46 13.04 12.49 27.81 27.30
9.08 21.41 21.15 47.98 47.07
Propylene Glycol:Water Mass Ratio ) 0:1
70 3.15 6.96
80 7.56 10.62 11.0
-
-
-
-
-
-
16.76
12.0
12.7
30.65 29.79 64.08 66.78
12.98 12.1 (0.15) 14.16 15.4
(0.26)
Ethylene Glycol:Water Mass Ratio ) 1:4
8
4.5 - 15.4
-
16.12 24.4
20.99 35.0
22.88 20
19.5
0
0
0
0
3.17
6.03
8.19
3.34
7.66
7.46 15.62 15.94
(0.2)
.1
.3
.5
5.02 11.71 11.47 25.74 25.09
8.36 19.84 19.48 45.67 43.35
90 15.9 15.82 22.5
31.32 30.3
26.16
(0.2)
10.20 11.70 25.54 27.46 60.60 61.55
Propylene Glycol:Water Mass Ratio ) 1:4
Ethylene Glycol:Water Mass Ratio ) 2:3
90 12.67 12.92 18.33
00 20
10 30
17.41 27.83
28.26 52.17
45.93 -
26.39 38.17 35.36
47.07 70.5
-
1
1
18.85 29.5
26.96 42.5
65.89
-
0
0
0
0
2.84
4.38
7.13
3.03
6.62
6.77 13.43 14.45
-
.1
.3
.5
4.56 10.75 10.44 22.50 22.82
7.62 19.41 17.75 49.93 39.52
Propylene Glycol:Water Mass Ratio ) 2:3
9.59 10.67 25.99 25.05 55.71 56.16
90 9.5 10.18 14.17
00 14.42 14.85 21.67
10 21.7 21.2 35.83
13.96 20.83
22.78 36.5 (0.31) 39.43 52.0
37.23 60.5 69.21 -
21.53 28.0
29.1
54.5
-
1
1
Ethylene Glycol:Water Mass Ratio ) 3:2
0
0
0
0
2.47
4.29
6.60
8.91
2.71
4.10
5.54
9.31
6.06 10.79 12.93
9.37 19.66 20.49
.1
.3
.5
Propylene Glycol:Water Mass Ratio ) 3:2
6.86 16.17 15.97 33.32 35.56
9.61 23.41 22.56 45.23 50.58
90 6.17 7.61 9.33
100 9.17 11.11 15.07
10.66 17.5
17.5 29.0
28.77 52.67
16.77 22.83 22.87
30.29 43.0
54.58 80.0
43.09
80.38
1
10 13.67 15.87 29.5
Ethylene Glycol:Water Mass Ratio ) 4:1
0
0
0
0
1.92
3.59
6.26
7.98
2.39
3.62
4.33
8.86
5.33
8.16 11.38
Ethylene Glycol:Water Mass Ratio ) 4:1
3.33 5.25 5.83 7.54 9.0 12.12 12.5
00 7.833 7.65 11.02 (0.08) 11.49 18.33 22.07 25.0
10 11.67 10.94 23.67 20.63 43.0
9
0
16.71
31.68
.1
.3
.5
8.27 19.02 18.09
6.07 15.02 14.13 33.16 31.47
8.51 21.85 20.00 45.19 44.80
1
1
40.0 69.83 59.39
Table 4. Values of experimental and computed
concentrations and yields of ethylene- and propylene oxide
at different initial molar ratios of oxide/water (â)
The best values of parameters of eq 8 which gives an
adequate description of the experimental data are listed
below:
[Gly], mol/L
monoglycol yield, %
ethylene oxide
â
exp
calc
exp
calc
2
2
k ) exp(9.077-9355/T) L /(mol s)
Ethylene Oxide
0
T ) 90 °C, [NaHCO
3
] ) 0.25 mol/L, kct/k
0
) 306
2
2
k ) exp(18.24 - 10574/T) L /(mol s); p ) 1.88
0.062
2.81
3.51
4.10
4.73
2.79
3.47
4.04
4.66
94.1
92.5
91.1
89.6
93.3
91.6
89.8
88.3
ct
0
0
0
.082
.101
.124
Propylene oxide
k ) exp(-2.71 - 5111/T) L /(mol s)
2
2
0
t ) 94 °C, [NaHCO
3
] ) 0.2 mol/L, kct/k ) 314
0
2
2
0.039
1.94
3.15
3.98
4.8
5.72
6.32
1.90
3.11
3.92
4.75
5.72
6.38
97.9
92.6
90.7
87.1
83.0
79.6
96.0
91.5
89.3
86.2
83.0
80.3
k ) exp(16.02 - 10020/T) L /(mol s); p ) 1.1
ct
0
0
0
.072
.098
.131
0.178
.220
According to experimental data the kinetic equation of
R-oxide hydration can be presented as:
0
-
d[oxide]/dτ ) (k ([H O] + b [Gly ]) +
Propylene Oxide
0
2
∑
i
T ) 94 °C, [NaHCO
3
] ) 0.25 mol/L, kct/k )211
0
-
k [HCO ])([H O] + p [Gly ])[oxide] (9)
0.0297
1.45
2.8
1.44
2.77
2.82
3.39
3.76
3.83
4.4
5.23
5.43
5.97
96.0
92.1
91.0
89.9
87.9
88.2
84.6
82.5
76.6
71.9
95.3
91.1
91.0
89.0
87.4
88.4
84.6
81.0
79.9
76.9
ct
3
2
∑
i
0
0
0
0
0
.0664
.068
.088
.103
.106
2.82
3.405
3.78
3.872
4.4
The adequacy of the obtained kinetic equation is confirmed
by good agreement of experimental and calculated values
of the first-order rate constants in a broad band of experi-
mental conditions (Tables 2 and 3).
The additional checking of the eqs 4 and 8 with
determined parameters was made in three series of experi-
ments on the analysis of monoglycol formed after full
conversion of oxide in the catalyzed hydration of the oxide-
water mixture in a wide range of oxide/water ratios (Table
0.134
0
0
0
.186
.202
.254
5.33
5.2
5.58
yields of monoglycol are much higher in the presence of
NaHCO . The reason is a quantitative monoglycol formation
4). As it is clear from the Table 4 and Figures 1 and 2 the
3
Vol. 6, No. 5, 2002 / Organic Process Research & Development
•
663

Figure 1. Calculated curves of monoethylene glycol yields vs
molar ratio (â) ethylene oxide/water and experimental points:
Figure 2. Calculated curves of monopropylene glycol yields
vs molar ratio (â) propylene oxide/water and experimental
points: (1) noncatalytic reaction at 94 °C; (2) reaction catalyzed
(
1) noncatalytic reaction at 90 and 94 °C; (2) reaction catalyzed
by NaHCO (0.2 mol/L) at 94 °C.
3
3
by NaHCO (0.25 mol/L) at 94 °C.
according to the reactions II-IV. The obtained kinetic model
makes it possible to calculate yields of monoglycol formed
in the presence of NaHCO . By division of eq 5 for catalytic
3
reaction by eq 4 we shall receive an equation for the
calculation of the yield of monoglycol with different
model describing the rates of the main (eq 9) and side ( eq
5) reactions and products distribution (eq 10) is obtained.
The parameters of the model were found from experi-
mental data that were obtained in a broad range of concen-
trations of reactants. The model can be utilized for design
and optimization of the working conditions of the industrial
catalytic reactor of a selective hydration of R-oxides in
concentrated aqueous solutions.
concentrations of NaHCO
3
and different oxide/water ratios:
-
d[Gly1]
k ([H O] - b[Gly ]) + k [HCO ]
0
2
1
ct
3
)
(10)
d[C H O]
-
2
4
k ([H O] + b [Gly ]) + k [HCO ]
0
2
∑
i
ct
3
Such calculations with the parameters obtained from kinetic
data give a good correlation of computed and experimental
values of monoglycol yields (Table 4, Figures 1 and 2). That
is the most convincing confirmation of the kinetic model
obtained and the mechanism of catalytic reaction proposed
with quantitative formation of monoglycol.
Acknowledgment
This work was financially supported by Ministry of
Education of Russian Federation in terms of Research
Program “New Investigations of the Higher School in the
Field of Chemistry and Chemical Products”.
Conclusions
Received for review December 18, 2000.
OP010099+
On the basis of the mechanism of the catalysis of selective
hydration of R-oxides proposed (reactions II-VI) the kinetic
664
•
Vol. 6, No. 5, 2002 / Organic Process Research & Development