Title of Invention

A PROCESS FOR THE PRODUCTION OF A HIGH-PURITY DIOL

Abstract It is an object of the present invention to provide a specific apparatus and process for producing a high-purity diol by taking a cyclic carbonate and an aliphatic monohydric alcohol as starting materials, continuously feeding the starting materials into a continuous multi-stage distillation column A in which a catalyst is present, carrying out reactive distillation in the column A, continuously withdrawing a low boiling point reaction mixture AT containing a produced dialkyl carbonate and the aliphatic monohydric alcohol from an upper portion of the column A in a gaseous form, continuously withdrawing a high boiling point reaction mixture AB containing a produced diol from a lower portion of the column A in a liquid form, continuously feeding the high boiling point reaction mixture AB into a continuous multi-stage distillation column C, distilling off material having a lower boiling point than that of the diol contained in the high boiling point reaction mixture AB as a column top component CT and / or a side cut component Cs so as to obtain a column bottom component CB, continuously feeding the column bottom component CB into a continuous multi-stage distillation column E, and obtaining the diol as a side cut component Es from a side cut outlet of the continuous multi-stage distillation column E. Moreover, it is an object to thus provide a specific industrial apparatus and industrial production process that are inexpensive and, for example, enable the high-purity diol to be produced in an amount of not less than 1 ton / hr stably for a prolonged period of time (e.g. not less than 1000 hours, preferably not less than 3000 hours, more preferably not less than 5000 hours). The above objects can be attained by using a continuous multi-stage distillation column E having a specified structure, and withdrawing a liquid component from the side cut outlet, which is installed at the bottom of a chimney tray having a specified structure installed in an enrichment section of the continuous multi-stage distillation column E.
Full Text A0501 VP84/KAN
INDUSTRIAL PROCESS FOR PRODUCTION OF HIGH-PURITY DIOL
Technical Field
The present invention relates to an industrial process for the
production of a high-purity diol in which a cyclic carbonate and an
aliphatic monohydric alcohol are continuously fed into a reactive
distillation column, and carrying out reactive distillation, and a high
boiling point reaction mixture having the diol as a main component
thereof is continuously withdrawn from the bottom of the reactive
distillation column, material having a lower boiling point than that of the
diol is distilled off from the high boiling point reaction mixture using a
continuous multi-stage distillation column, and a column bottom
component from the continuous multi-stage distillation column is fed into
a continuous multi-stage distillation column having a specified structure,
and the diol is continuously obtained as a side cut component.
Background Art
A reactive distillation process for producing a dialkyl carbonate
and a diol through reaction between a cyclic carbonate and an aliphatic
monohydric alcohol was first disclosed by the present inventors (see
Patent Document 1: Japanese Patent Application Laid-Open No.
4-198141, Patent Document 2: Japanese Patent Application Laid-Open
No. 4-230243, Patent Document 3: Japanese Patent Application
Laid-Open No. 9-176061, Patent Document 4: Japanese Patent
i Application Laid-Open No. 9-183744, Patent Document 5: Japanese
Patent Application Laid-Open No. 9-194435, Patent Document 6:
l

A0501 VP84/KAN
International Publication No. W097/23445 (corresponding to European
Patent No. 0889025, and U.S. Patent No. 5847189), Patent Document 7:
International Publication No. W099/64382 (corresponding to European
Patent No. 1086940, and U.S. Patent No. 6346638), Patent Document 8:
International Publication No. WO00/51954 (corresponding to European
Patent No. 1174406, and U.S. Patent No. 6479689), Patent Document 9:
Japanese Patent Application Laid-Open No. 2002-308804, Patent
Document 10: Japanese Patent Application Laid-Open No. 2004-131394),
and patent applications in which such a reactive distillation system is
used have subsequently also been filed by other companies (see Patent
Document 11: Japanese Patent Application Laid-Open No. 5-213830
(corresponding to European Patent No. 0530615, and U.S. Patent No.
5231212), Patent Document 12: Japanese Patent Application Laid-Open
No. 6-9507 (corresponding to European Patent No. 0569812, and U.S.
Patent No. 5359118), Patent Document 13: Japanese Patent Application
Laid-Open No. 2003-119168 (corresponding to International Publication
No. WO03/006418), Patent Document 14: Japanese Patent Application
Laid-Open No. 2003-300936, Patent Document 15: Japanese Patent
Application Laid-Open No. 2003-342209). In the case of using the
reactive distillation system for this reaction, the reaction can be made to
proceed with a high conversion. However, reactive distillation
processes proposed hitherto have related to producing the dialkyl
carbonate and the diol either in small amounts or for a short period of
time, and have not related to carrying out the production on an industrial
scale stably for a prolonged period of time. That is, these processes
have not attained the object of producing a diol continuously in a large
2

A0501 VP84/KAN
amount (e.g. not less than 1 ton / hr) stably for a prolonged period of
time (e.g. not less than 1000 hours, preferably not less than 3000 hours,
more preferably not less than 5000 hours).
For example, the maximum values of the height (H: cm), diameter
(D: cm), and number of stages (n) of the reactive distillation column, the
amount produced P (kg / hr) of ethylene glycol, and the continuous
production time T (hr) in examples disclosed for the production of
dimethyl carbonate (DMC) and ethylene glycol (EG) from ethylene
carbonate and methanol are as in Table 1.
Table 1
TABLE 1

PATENT
DOCUMENT H : cm D : cm NO. STAGES : n P: kg/hr T:hr
1 100 2 30 0.073 400
4 160 5 40 0.213 NOTE 5
5 160 5 40 0.358 NOTE 5
7 200 4 PACKING COLUMN (Dixon) 0.528 NOTE 5
8 NOTE1 5 60 0.140 NOTE 5
9 NOTE1 5 60 0.161 NOTE 5
10 NOTE1 5 60 0.161 NOTE 5
11 250 3 PACKING COLUMN (Raschig) 0.154 NOTE 5
12 NOTE 2 NOTE 2 NOTE 2 0.256 NOTE 5
13 NOTE 3 NOTE 3 42 NOTE 4 NOTE 5
14 NOTE 3 NOTE 3 30 2490 NOTE 5
15 200 15 PACKING COLUMN (BX) 19 NOTE 5
NOTE 1 : OLDERSHAW DISTILLATION COLUMN.
NOTE 2 : NO DESCRIPTION WHATSOEVER DEFINING DISTILLATION COLUMN.
NOTE 3 : ONLY DESCRIPTION DEFINING DISTILLATION COLUMN IS
NUMBER OF STAGES.
NOTE 4 : NO DESCRIPTION WHATSOEVER OF PRODUCED AMOUNT.
NOTE 5 : NO DESCRIPTION WHATSOEVER REGARDING STABLE
PRODUCTION FOR PROLONGED PERIOD OF TIME.
3

A0501 VP84/KAN
In Patent Document 14 (Japanese Patent Application Laid-Open
No. 2003-300936), it is stated at paragraph 0060 that "The present
example uses the same process flow as for the preferred mode shown in
FIG. 1 described above, and was carried out with the object of operating
a commercial scale apparatus for producing dimethyl carbonate and
ethylene glycol through transesterification by a catalytic conversion
reaction between ethylene carbonate and methanol. Note that the
following numerical values in the present example can be adequately
used in the operation of an actual apparatus", and as that example it is
stated that 3750 kg / hr of dimethyl carbonate and 2490 kg / hr of
ethylene glycol were specifically produced. The scale described in that
example corresponds to an annual production of 30,000 or more tons of
dimethyl carbonate, and hence this implies that operation of the world's
largest scale commercial plant using this process had been carried out at
the time of the filing of the patent application for Patent Document 14
(Japanese Patent Application Laid-Open No. 2003-300936) (April 9,
2002). However, even at the time of filing the present application, there
is not the above fact at all. Moreover, in the example of Patent
Document 14 (Japanese Patent Application Laid-Open No. 2003-300936),
exactly the same value as the theoretically calculated value is stated for
the amount of dimethyl carbonate produced, but the yield for ethylene
glycol is approximately 85.6%, and the selectivity is approximately 88.4%,
and hence it cannot really be said that a high yield and high selectivity
have been attained. In particular, the low selectivity indicates that this
process has a fatal drawback as an industrial production process. (Note
also that Patent Document 14 (Japanese Patent Application Laid-Open
4

A.0501 VP84/KAN
No. 2003-300936) was deemed to have been withdrawn on July 26, 2005
due to examination not having been requested).
With such a reactive distillation process, there are very many
causes of fluctuation such as composition variation due to reaction and
composition variation due to distillation in the distillation column, and
temperature variation and pressure variation in the column, and hence
continuing stable operation for a prolonged period of time is often
accompanied by difficulties, and in particular these difficulties are further
increased in the case of handling large amounts. To continue mass
production of a dialkyl carbonate and a diol using the reactive distillation
process stably for a prolonged period of time while maintaining high yield
and high selectivity, and thus produce a high-purity diol, the process
must be cleverly devised. However, the only description of continuous
stable production for the prolonged period of time with the reactive
distillation process proposed hitherto has been the 200 to 400 hours in
Patent Document 1 (Japanese Patent Application Laid-Open No.
4-198141) and Patent Document 2 (Japanese Patent Application
Laid-Open No. 4-230243).
The present inventors have proposed an industrial reactive
distillation process that enables a dialkyl carbonate and a diol to be
mass-produced continuously and stably for a prolonged period of time
with high yield and high selectivity, but in addition to this, a process
enabling a high-purity diol to be separated out and purified in a large
amount stably for a prolonged period of time from a high boiling point
reaction mixture continuously withdrawn in a large amount from a lower
portion of the reactive distillation column is also required, a process for
5

A0501 VP84/KAN
producing a large amount of a high-purity diol with a high yield having
been called for. The present invention has been devised to attain this
object.
As shown in Table 1, with the exception of Patent Document 14
(Japanese Patent Application Laid-Open No. 2003-300936), the amount
of the diol produced per hour using the reactive distillation processes
proposed hitherto has been a small amount. Moreover, with the process
of Patent Document 14 (Japanese Patent Application Laid-Open No.
2003-300936), it is stated that approximately 2490 kg / hr of ethylene
glycol containing approximately 130 kg / hr of unreacted ethylene
carbonate and approximately 226 kg / hr of dihydroxyethyl carbonate was
obtained as a column bottom component from a fourth step distillation
column. However, this is merely a statement of the composition of the
reaction mixture, there being no description whatsoever of production of
a high-purity diol.
As a process for producing a diol of relatively high purity using
reactive distillation and a diol purifying column, a process is known in
which the diol is obtained from a side cut of the diol purifying column.
For example, in the example (FIG. 5) in Patent Document 12 (Japanese
Patent Application Laid-Open No. 6-9507 (corresponding to European
Patent No. 0569812, and U.S. Patent No. 5359118)), a high boiling point
reaction mixture withdrawn from a lower portion of a reactive distillation
column is fed into a thin film evaporator (III), high boiling point matter
obtained therefrom is fed into a thin film evaporator (IV), low boiling point
evaporated matter obtained therefrom is fed into a distillation column
(VII), and ethylene glycol is obtained as a side cut component 22 from an
6

A0501 VP84/KAN
enrichment section of the distillation column (VII), and then purification is
further carried out using a purifier (IX), whereby high-purity ethylene
glycol is produced in an amount of 255 g / hr. That is, in the process of
Patent Document 12 (Japanese Patent Application Laid-Open No. 6-9507
(corresponding to European Patent No. 0569812, and U.S. Patent No.
5359118)), high-purity ethylene glycol is not obtained from the high
boiling point reaction mixture until four purifying apparatuses have been
used. Furthermore, the process of Patent Document 12 (Japanese
Patent Application Laid-Open No. 6-9507 (corresponding to European
Patent No. 0569812, and U.S. Patent No. 5359118)) is a process in
which a small amount of ethylene glycol is produced, there being no
suggestions whatsoever regarding a process for producing a large
amount (e.g. not less than 1 ton / hr) of a diol stably for a prolonged
period of time (e.g. not less than 5000 hours).
Moreover, in, for example, example 1 (FIG. 5) in Patent Document
15 (Japanese Patent Application Laid-Open No. 2003-342209), a high
boiling point reaction mixture withdrawn from a lower portion of a
reactive distillation column is fed into a second distillation column 4, high
boiling point matter obtained therefrom is fed into a hydrolysis reactor 7,
the reaction mixture therefrom is fed into a decarboxylation tank
(gas-liquid separator 8), a liquid component obtained therefrom is fed
into a third distillation column 10, and ethylene glycol is produced in an
amount of 19 kg / hr as a side cut component from a stripping section of
the third distillation column 10. However, with the process of Patent
Document 15 (Japanese Patent Application Laid-Open No. 2003-342209),
the ethylene glycol obtained contains 0.2 % by weight of diethylene
7

A0501 VP84/KAN
glycol. To obtain ethylene glycol of a high purity as required as a
starting material for a PET fiber or a PET resin using the process of
Patent Document 15 (Japanese Patent Application Laid-Open No.
2003-342209), at least one further purifying apparatus is thus required.
That is, with the process of Patent Document 15 (Japanese Patent
Application Laid-Open No. 2003-342209), ethylene glycol is obtained
from a side cut outlet installed in the stripping section, which is below an
inlet for feeding into the distillation column, but the purity of the ethylene
glycol is insufficient, and moreover the process of Patent Document 15
(Japanese Patent Application Laid-Open No. 2003-342209) is a process
in which a small amount of ethylene glycol is produced, there being no
suggestions whatsoever regarding a process for producing a large
amount (e.g. not less than 1 ton / hr) of a diol stably for a prolonged
period of time (e.g. not less than 5000 hours).
Moreover, in, for example, example 10 (FIG. 6) in Patent
Document 8 (International Publication No. WO00/51954 (corresponding
to European Patent No. 1174406, and U.S. Patent No. 6479689)) and
example 1 (FIG. 1) in Patent Document 9 (Japanese Patent Application
Laid-Open No. 2002-308804), high-purity ethylene glycol is obtained from
a side cut outlet installed in an enrichment section of an EG purifying
column 41, which is above an inlet for feeding into the column, but in
each case the amount produced is a small amount of less than 200 g / hr,
there being no suggestions whatsoever regarding a process for
producing a large amount (e.g. not less than 1 ton / hr) of a diol stably
for a prolonged period of time (e.g. not less than 5000 hours).
Approximately 16 million tons per year (2004) of ethylene glycol is
8

A0501 VP84/KAN
produced worldwide, but hitherto all of this has been through a hydration
method in which water is added to ethylene oxide. However, as shown
by the statement "Production of EG (ethylene glycol) is by a hydration
reaction of EO (ethylene oxide), the reaction generally being carried out
... at 150 to 200 °C. At this time, not only is the target substance MEG
(monoethylene glycol) produced, but moreover DEG (diethylene glycol)
and TEG (triethylene glycol) are also by-produced. The proportions of
these products depend on the water / EO ratio, and to obtain MEG with a
selectivity of approximately 90%, the water / EO ratio must be made to
be approximately 20 as a molar ratio. A large amount of water must
thus be distilled off in an EG purification step, and a large amount of
thermal energy is consumed in this. ... With regard to synthesis of EG
from EO, it is not an overstatement to say that this is an imperfect
process from the viewpoint of energy efficiency." in Non-Patent
Document 1 (Japan Petroleum Institute (ed.), "Sekiyu-kagaku Purosesu"
("Petrochemical Processes"), pages 120 to 125, Kodansha, 2001), this
industrial production process (conventional process) has great
drawbacks both from the perspective of the ethylene glycol yield and
selectivity, and the perspective of energy saving.
Disclosure of Invention
Problems to be Solved by the Invention
It is an object of the present invention to provide a specific
apparatus and process for producing a high-purity diol by taking a cyclic
carbonate and an aliphatic monohydric alcohol as starting materials,
continuously feeding the starting materials into a continuous multi-stage
9

A0501 VP84/KAN
distillation column A in which a catalyst is present, carrying out reactive
distillation in the column A, continuously withdrawing a low boiling point
reaction mixture Ay containing a produced dialkyl carbonate and the
aliphatic monohydric alcohol from an upper portion of the column A in a
gaseous form, continuously withdrawing a high boiling point reaction
mixture AB containing a produced diol from a lower portion of the column
A in a liquid form, continuously feeding the high boiling point reaction
mixture AB into a continuous multi-stage distillation column C, distilling
off material having a lower boiling point than the diol contained in the
high boiling point reaction mixture AB as a column top component CT and
/ or a side cut component Cs so as to obtain a column bottom component
CB, continuously feeding the column bottom component CB into a
continuous multi-stage distillation column E, and obtaining the diol as a
side cut component Es from a side cut outlet of the continuous
multi-stage distillation column E. Moreover, it is an object to thus
provide a specific industrial apparatus and industrial production process
that are inexpensive and, for example, enable the high-purity diol to be
produced in an amount of not less than 1 ton / hr stably for a prolonged
period of time (e.g. not less than 1000 hours, preferably not less than
3000 hours, more preferably not less than 5000 hours).
That is, in a first aspect of the present invention, there are
provided:
1. an industrial process for the production of a high-purity diol in which
a high-purity diol is produced by taking a cyclic carbonate and an
aliphatic monohydric alcohol as starting materials, continuously feeding
the starting materials into a continuous multi-stage distillation column A
10

A0501 VP84/KAN
in which a catalyst is present, carrying out reactive distillation in said
column A, continuously withdrawing a low boiling point reaction mixture
AT containing a produced dialkyl carbonate and the aliphatic monohydric
alcohol from an upper portion of the column A in a gaseous form,
continuously withdrawing a high boiling point reaction mixture AB
containing a produced diol from a lower portion of the column A in a
liquid form, continuously feeding said high boiling point reaction mixture
AB into a continuous multi-stage distillation column C, distilling off
material having a lower boiling point than the diol contained in said high
boiling point reaction mixture AB as a column top component CT and / or
a side cut component Cs so as to obtain a column bottom component CB,
continuously feeding the column bottom component CB into a continuous
multi-stage distillation column E, and obtaining the diol as a side cut
component Es from a side cut outlet of the continuous multi-stage
distillation column E, wherein:

11
(a) said continuous multi-stage distillation column E comprises a
distillation column comprising a stripping section having a length l_i (cm),
an inside diameter Di (cm) and an internal with a number of stages ni
thereinside, and an enrichment section having a length l_2 (cm), an inside
diameter D2 (cm) and an internal with a number of stages n2 thereinside,
wherein L-i, Di, n-i, L2, D2, and n2 satisfy the following formulae (1) to (9):

A0501 VP84/KAN
100 2 5 Di (b) the enrichment section of said continuous multi-stage
distillation column E has at least one chimney tray as an internal
installed therein, said chimney tray having installed therein at least two
chimneys each having an opening having a cross-sectional area S (cm2)
satisfying the formula (10):
50 and each of the chimneys being such that a height h (cm) from the
opening of the chimney to a gas outlet of the chimney satisfies the
formula (11):
20 (c) the diol is continuously withdrawn in a liquid form from the side
cut outlet, which is connected to a liquid collecting section of said
chimney tray of said continuous multi-stage distillation column E,
2. the process according to item 1, wherein a produced amount of the
high-purity diol is not less than 1 ton / hr,
3. the process according to item 1 or 2, wherein L-i, Di, L-i / Di, ni, L2,
D2, L2 / D2, and n2 for said continuous multi-stage distillation column E
satisfy 500 4. the process according to any one of items 1 to 3, wherein an internal
excluding the chimney tray in each of the stripping section and the
enrichment section of said continuous multi-stage distillation column E is
12

A0501 VP84/KAN
a tray and / or a packing,
5. the process according to item 4, wherein the internal excluding the
chimney tray in each of the stripping section and the enrichment section
of said continuous multi-stage distillation column E is the tray,
6. the process according to item 5, wherein said tray is a sieve tray,
7. the process according to item 6, wherein said sieve tray has 150 to
1200 holes / m2 in a sieve portion thereof, and a cross-sectional area per
hole in a range of from 0.5 to 5 cm2,
8. the process according to item 6 or 7, wherein said sieve tray has 200
to 1100 holes / m2 in a sieve portion thereof, and a cross-sectional area
per hole in a range of from 0.7 to 4 cm2,
9. the process according to any one of items 6 to 8, wherein said sieve
tray has 250 to 1000 holes / m2 in a sieve portion thereof, and a
cross-sectional area per hole in a range of from 0.9 to 3 cm2,

10. the process according to any one of items 6 to 9, wherein an
aperture ratio (a ratio of a total cross-sectional area of the hole in one
tray stage to an area of the tray) of said sieve tray in the stripping
section of said continuous multi-stage distillation column E is in a range
of from 3 to 25%,
11. the process according to any one of items 6 to 10, wherein an
aperture ratio (a ratio of a total cross-sectional area of the hole in one
tray stage to an area of the tray) of said sieve trays in the enrichment of
said continuous multi-stage distillation column E is in a range of from 2
to 20%,
12. the process according to any one of items 1 to 11, wherein an
aperture ratio (a ratio of a total cross-sectional area of the opening in the
13

A0501 VP84/KAN
chimney to an area of the chimney tray including the total cross-sectional
area of the opening) of the chimney tray is in a range of from 5 to 40%,
13. the process according to any one of items 1 to 12, wherein a
column bottom temperature of said continuous multi-stage distillation
column E is in a range of from 110 to 210 °C,
14. the process according to any one of items 1 to 13, wherein a reflux
ratio of said continuous multi-stage distillation column E is in a range of
from 6 to 100,
15. the process according to any one of items 1 to 14, wherein a purity
of the diol in said side cut component Es is not less than 99%,
16. the process according to any one of items 1 to 15, wherein a purity
of the diol in said side cut component Es is not less than 99.9%.
Further, according to the second aspect of the present invention,
there are provided:
17. a high-purity diol produced by the process according to any one of
items 1 to 16, which comprises a content of high boiling point impurities
such as a dialkylene glycol of not more than 200 ppm, and a halogen
content of not more than 0.1 ppm,
18. a high-purity diol produced by the process according to any one of
Claims 1 to 16, which comprises a content of high boiling point impurities
such as a dialkylene glycol of not more than 100 ppm, and a halogen
content of not more than 1 ppb.
Furthermore, according to the third aspect of the present invention,
there are provided:
19. a continuous multi-stage distillation column being a continuous
multi-stage distillation column E for producing a high-purity diol by taking
14

A0501 VP84/KAN
a cyclic carbonate and an aliphatic monohydric alcohol as starting
materials, continuously feeding the starting materials into a continuous
multi-stage distillation column A in which a catalyst is present, carrying
out reactive distillation in said column A, continuously withdrawing a low
boiling point reaction mixture AT containing a produced dialkyl carbonate
and the aliphatic monohydric alcohol from an upper portion of said
column A in a gaseous form, continuously withdrawing a high boiling
point reaction mixture AB containing a produced diol from a lower portion
of said column A in a liquid form, continuously feeding said high boiling
point reaction mixture AB into the continuous multi-stage distillation
column C, distilling off material having a lower boiling point than the diol
contained in said high boiling point reaction mixture AB as a column top
component CT and / or a side cut component Cs so as to obtain a column
bottom component CB, continuously feeding the column bottom
component CB into said continuous multi-stage distillation column E, and
obtaining the diol as a side cut component Es from a side cut outlet of
the continuous multi-stage distillation column E, wherein:
(a) said continuous multi-stage distillation column E comprises a
distillation column comprising a stripping section having a length L-i (cm),
an inside diameter D-i (cm) and an internal with a number of stages ni
thereinside, and an enrichment section having a length l_2 (cm), an inside
diameter D2 (cm) and an internal with a number of stages n2 thereinside,
wherein l_i, D-i, n-i, L2, D2, and n2 satisfy the following formulae (1) to (9):
400 50 2 15

A0501 VP84/KAN

(b) the enrichment section ot said continuous multi-stage
distillation column E has at least one chimney tray as an internal
installed therein, said chimney tray having installed therein at least two
chimneys each having an opening having a cross-sectional area S (cm2)
satisfying the formula (10):
50 and each of the chimneys being such that a height h (cm) from the
opening of the chimney to a gas outlet of the chimney satisfies the
formula (11):
20 (c) the side cut outlet installed for continuously withdrawing the
high-purity diol in a liquid form from said continuous multi-stage
distillation column E is connected to a liquid collecting section of said
chimney tray,
20. the continuous multi-stage distillation column according to item 19,
wherein l_i, Di, L1 / D1t ni, L2, D2, L2 / D2) and n2 satisfy 500 100 800, 3 21. the continuous multi-stage distillation column according to item 19
or 20, wherein an internal excluding the chimney tray in each of the
16

A0501 VP84/KAN
stripping section and the enrichment section is a tray and / or a packing,
22. the continuous multi-stage distillation column according to item 21,
wherein the internal excluding the chimney tray in each of the stripping
section and the enrichment section is the tray,
23. the continuous multi-stage distillation column according to item 22,
wherein said tray is a sieve tray,
24. the continuous multi-stage distillation column according to item 23,
wherein said sieve trays has 150 to 1200 holes/m2 in a sieve portion
thereof, and a cross-sectional area per hole in a range of from 0.5 to 5
cm2,
25. the continuous multi-stage distillation column according to item 23
or 24, wherein said sieve trays has 200 to 1100 holes/m2 in a sieve
portion thereof, and a cross-sectional area per hole in a range of from
0.7 to 4 cm2,
26. the continuous multi-stage distillation column according to any one
of items 23 to 25, wherein said sieve trays has 250 to 1000 holes / m2 in
a sieve portion thereof, and a cross-sectional area per hole in a range of
from 0.9 to 3 cm2,

27. the continuous multi-stage distillation column according to any one
of items 23 to 26, wherein an aperture ratio (a ratio of a total
cross-sectional area of the hole in one tray stage to an area of the tray)
of said sieve tray in the stripping section is in a range of from 3 to 25%,
28. the continuous multi-stage distillation column according to any one
of items 23 to 27, wherein an aperture ratio (a ratio of a total
cross-sectional area of the hole in one tray stage to an area of the tray)
of said sieve tray in the enrichment section is in a range of from 2 to
17

A0501 VP84/KAN
20%,
29. the continuous multi-stage distillation column according to any one
of items 23 to 28, wherein an aperture ratio (a ratio of a total
cross-sectional area of the opening in the chimney to an area of the
chimney tray including the total cross-sectional area of the opening) of
the chimney tray is in a range of from 5 to 40%.
Advantageous Effects of the Invention
It has been found that according to the specific apparatus and
process provided by the present invention, a high-purity diol can be
produced from a cyclic carbonate and an aliphatic monohydric alcohol
stably for a prolonged period of time on an industrial scale with a high
yield (e.g. generally not less than 97%, preferably not less than 98%,
more preferably not less than 99%, based on the cyclic carbonate used).
That is, according to the present invention, there can be provided an
industrial apparatus and industrial production process that are
inexpensive and, for example, enable a high-purity diol of purity not less
than 99.9% as required as a starting material for a PET fiber or a PET
resin to be produced in an amount of not less than 1 ton / hr stably for a
prolonged period of time (e.g. not less than 1000 hours, preferably not
less than 3000 hours, more preferably not less than 5000 hours).
Moreover, the process according to the present invention differs
from the conventional ethylene glycol production process in that
high-purity ethylene glycol can be produced by the process according to
the present invention with a high yield and a high selectivity without
using a large amount of water, and thus achieves excellent effects as an
18

A0501 VP84/KAN
industrial production process that simultaneously solves two
long-standing problems with the conventional industrial production
process (low selectivity, high energy use).
Brief Description of Drawings
FIG. 1 is a schematic view showing an example of a continuous
multi-stage distillation column E preferable for carrying out the present
invention, ni and n2 stages of trays being installed in a stripping section
and an enrichment section respectively as an internal in a trunk portion,
and one chimney tray stage being installed in the enrichment section
above an inlet 1 (in FIG. 1, the trays except for the chimney tray are
omitted).
Description of Reference Numerals
1: inlet, 2: outlet of column top component ET, 3: outlet of column
bottom component EB, 4: outlet of side cut component Es, 5: inlet, 6:
heat exchanger, 7: reboiler, 8: inlet of reflux liquid, 9: chimney tray,
h: height (cm) from an opening of chimney to a gas outlet of chimney,
L-i: length (cm) of stripping section of continuous multi-stage distillation
column E, L2: length of enrichment section of continuous multi-stage
distillation column E, Di: inside diameter (cm) of stripping section of
continuous multi-stage distillation column E, D2: inside diameter (cm) of
enrichment section of continuous multi-stage distillation column E.
Best Mode for Carrying Out the Invention
Following is a detailed description of the present invention.
19

A0501 VP84/KAN
The reaction of the present invention is a reversible equilibrium
transesterification reaction represented by the following formula in which
a dialkyl carbonate and a diol are produced from a cyclic carbonate and
an aliphatic monohydric alcohol;
,R\ R^ OR2 RI
+ 28*°H *=* Y + m' Nil
I
(A) (B) (C) (D)
wherein R1 represents a bivalent group -(CH2)m- (m is an integer from 2
to 6), one or more of the hydrogens thereof being optionally substituted
with an alkyl group or aryl group having 1 to 10 carbon atoms. Moreover,
R2 represents a monovalent aliphatic group having 1 to 12 carbon atoms,
one or more of the hydrogens thereof being optionally substituted with an
alkyl group or aryl group having 1 to 10 carbon atoms.
The cyclic carbonate used as a starting material in the present
invention is a compound represented by (A) in the above formula. For
example, an alkylene carbonate such as ethylene carbonate or propylene
carbonate, or 1,3-dioxacyclohexa-2-one, 1,3-dioxacyclohepta-2-one, or
the like can be preferably used, ethylene carbonate or propylene
carbonate being more preferably used due to ease of procurement and
so on, and ethylene carbonate being particularly preferably used.
Moreover, the aliphatic monohydric alcohol used as the other
starting material is a compound represented by (B) in the above formula,
one having a lower boiling point than that of the diol produced being
used. Although possibly varying depending on the type of the cyclic
20

carbonate used, examples of aliphatic monohydric alcohol include
methanol, ethanol, propanol (isomers), allyl alcohol, butanol (isomers),
3-buten-1-ol, amyl alcohol (isomers), hexyl alcohol (isomers), heptyl
alcohol (isomers), octyl alcohol (isomers), nonyl alcohol (isomers), decyl
alcohol (isomers), undecyl alcohol (isomers), dodecyl alcohol (isomers),
cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol,
methylcyclopentanol (isomers), ethylcyclopentanol (isomers),
methylcyclohexanol (isomers), ethylcyclohexanol (isomers),
dimethylcyclohexanol (isomers), diethylcyclohexanol (isomers),
phenylcyclohexanol (isomers), benzyl alcohol, phenethyl alcohol
(isomers), phenylpropanol (isomers), and so on. Furthermore, these
aliphatic monohydric alcohols may be substituted with substituents such
as halogens, lower alkoxy groups, cyano groups, alkoxycarbonyl groups,
aryloxycarbonyl groups, acyloxy groups, and nitro groups.
Of such aliphatic monohydric alcohols, ones preferably used are
alcohols having 1 to 6 carbon atoms, more preferably alcohols having 1
to 4 carbon atoms, i.e. methanol, ethanol, propanol (isomers), and
butanol (isomers). In the case of using ethylene carbonate or propylene
carbonate as the cyclic carbonate, preferable aliphatic monohydric
alcohols are methanol and ethanol, methanol being particularly
preferable.
In the process of the present invention, a catalyst is made to be
present in a reactive distillation column A. The method of making the
catalyst be present in the reactive distillation column A may be any
method, but in the case, for example, of a homogeneous catalyst that
dissolves in the reaction liquid under the reaction conditions, the catalyst
21

A0501 VP84/KAN
can be made to be present in a liquid phase in the reactive distillation
column by feeding the catalyst into the reactive distillation column
continuously, or in the case of a heterogeneous catalyst that does not
dissolve in the reaction liquid under the reaction conditions, the catalyst
can be made to be present in the reaction system by disposing the
catalyst as a solid in the reactive distillation column; these methods may
also be used in combination.
In the case that a homogeneous catalyst is continuously fed into
the reactive distillation column, the homogeneous catalyst may be fed in
together with the cyclic carbonate and/or the aliphatic monohydric
alcohol, or may be fed in at a different position to the starting materials.
The reaction actually proceeds in the distillation column in a region
below the position at which the catalyst is fed in, and hence it is
preferable to feed the catalyst into a region between the top of the
column and the position(s) at which the starting materials are fed in.
The catalyst must be present in at least 5 stages, preferably at least 7
stages, more preferably at least 10 stages.
Moreover, in the case of using a heterogeneous solid catalyst, the
catalyst must be present in at least 5 stages, preferably at least 7 stages,
more preferably at least 10 stages. A solid catalyst that also has an
effect as a packing in the distillation column may also be used.
As the catalyst used in the present invention, any of various
catalysts known from hitherto can be used. Examples include;
alkali metals and alkaline earth metals such as lithium, sodium,
potassium, rubidium, cesium, magnesium, calcium, strontium, and
barium;
22

A0501 VP84/KAN
basic compounds of alkali metals and alkaline earth metals such
as hydrides, hydroxides, alkoxides, aryloxides, and amides;
basic compounds of alkali metals and alkaline earth metals such
as carbonates, bicarbonates, and organic acid salts;
tertiary amines such as triethylamine, tributylamine, trihexylamine,
and benzyldiethylamine;
nitrogen-containing heteroaromatic compounds such as
N-alkylpyrroles, N-alkylindoles, oxazoles, N-alkylimidazoles,
N-alkylpyrazoles, oxadiazoles, pyridine, alkylpyridines, quinoline,
alkylquinolines, isoquinoline, alkylisoquinolines, acridine, alkylacridines,
phenanthroline, alkylphenanthrolines, pyrimidine, alkylpyrimidines,
pyrazine, alkylpyrazines, triazines, and alkyltriazines;
cyclic amidines such as diazobicycloundecene (DBU) and
diazobicyclononene (DBN);
thallium compounds such as thallium oxide, thallium halides,
thallium hydroxide, thallium carbonate, thallium nitrate, thallium sulfate,
and thallium organic acid salts;
tin compounds such as tributylmethoxytin, tributylethoxytin,
dibutyldimethoxytin, diethyldiethoxytin, dibutyldiethoxytin,
dibutylphenoxytin, diphenylmethoxytin, dibutyltin acetate, tributyltin
chloride, and tin 2-ethylhexanoate;
zinc compounds such as dimethoxyzinc, diethoxyzinc,
ethylenedioxyzinc, and dibutoxyzinc;
aluminum compounds such as aluminum trimethoxide, aluminum
triisopropoxide, and aluminum tributoxide;
titanium compounds such as tetramethoxytitanium,
23

A0501 VP84/KAN
tetraethoxytitanium, tetrabutoxytitanium, dichlorodimethoxytitanium,
tetraisopropoxytitanium, titanium acetate, and titanium acetylacetonate;
phosphorus compounds such as trimethylphosphine,
triethylphosphine, tributylphosphine, triphenylphosphine,
tributylmethylphosphonium halides, trioctylbutylphosphonium halides,
and triphenylmethylphosphonium halides;
zirconium compounds such as zirconium halides, zirconium
acetylacetonate, zirconium alkoxides, and zirconium acetate;
lead and lead-containing compounds, for example lead oxides
such as PbO, Pb02, and Pb304;
lead sulfides such as PbS, Pb2S3, and PbS2;
lead hydroxides such as Pb(OH)2, Pb302(OH)2, Pb2[Pb02(OH)2],
and Pb20(OH)2;
plumbites such as Na2Pb02, K2Pb02, NaHPb02, and KHPb02;
plumbates such as Na2Pb03, Na2H2Pb04, K2Pb03, K2[Pb(0H)6],
K4Pb04, Ca2Pb04, and CaPb03;
lead carbonates and basic salts thereof such as PbC03 and
2PbC03Pb(OH)2;
alkoxylead compounds and aryloxylead compounds such as
Pb(OCH3)2, (CH30)Pb(OPh), and Pb(OPh)2;
lead salts of organic acids, and carbonates and basic salts thereof,
such as Pb(OCOCH3)2, Pb(OCOCH3)4, and Pb(0C0CH3)2PbO3H20;
organolead compounds such as Bu4Pb, Ph4Pb, Bu3PbCI, Ph3PbBr,
Ph3Pb (or Ph6Pb2), Bu3PbOH, and Ph2PbO (wherein Bu represents a
butyl group, and Ph represents a phenyl group);
lead alloys such as Pb-Na, Pb-Ca, Pb-Ba, Pb-Sn, and Pb-Sb;
24

A0501 VP84/KAN
lead minerals such as galena and zinc blende; and hydrates of
such lead compounds.
In the case that the compound used dissolves in a starting
material of the reaction, the reaction mixture, a reaction by-product or
the like, the compound can be used as a homogeneous catalyst, whereas
in the case that the compound does not dissolve, the compound can be
used as a solid catalyst. Furthermore, it is also preferable to use, as a
homogeneous catalyst, a mixture obtained by dissolving a compound as
above in a starting material of the reaction, the reaction mixture, a
reaction by-product or the like in advance, or by reacting to bring about
dissolution.
Furthermore, ion exchangers such as anion exchange resins
having tertiary amino groups, ion exchange resins having amide groups,
ion exchange resins having at least one type of exchange groups
selected from sulfonate groups, carboxylate groups and phosphate
groups, and solid strongly basic anion exchangers having quaternary
ammonium groups as exchange groups; solid inorganic compounds such
as silica, silica-alumina, silica-magnesia, aluminosilicates, gallium
silicate, various zeolites, various metal-exchanged zeolites, and
ammonium-exchanged zeolites, and so on can also be used as a
heterogeneous catalyst.
As a heterogeneous catalyst, a particularly preferably used one is
a solid strongly basic anion exchanger having quaternary ammonium
groups as exchange groups, examples thereof including a strongly basic
anion exchange resin having quaternary ammonium groups as exchange
groups, a cellulose strongly basic anion exchanger having quaternary
25

A0501 VP84/KAN
ammonium groups as exchange groups, and an inorganic carrier
supported type strongly basic anion exchanger having quaternary
ammonium groups as exchange groups. As a strongly basic anion
exchange resin having quaternary ammonium groups as exchange groups,
for example a styrene type strongly basic anion exchange resin or the
like can be preferably used. A styrene type strongly basic anion
exchange resin is a strongly basic anion exchange resin having a
copolymer of styrene and divinylbenzene as a parent material, and
having quaternary ammonium groups (type I or type II) as exchange
groups, and can be schematically represented, for example, by the
following formula;

wherein X represents an anion; as X, generally at least one type of anion
selected from F, CI', Br, I", HC03", C032", CH3C02", HC02", I03", Br03",
and CI03" is used, preferably at least one type of anion selected from CI",
26

A0501 VP84/KAN
Br", HC03", and CO32". Moreover, as the structure of the resin parent
material, either a gel type one or a macroreticular (MR) type one can be
used, the MR type being particularly preferable due to the organic
solvent resistance being high.
An example of a cellulose strongly basic anion exchanger having
quaternary ammonium groups as exchange groups is cellulose having
-OCH2CH2NR3X exchange groups obtained by converting some or all of
the -OH groups in the cellulose into trialkylaminoethyl groups. Here, R
represents an alkyl group; methyl, ethyl, propyl, butyl or the like is
generally used, preferably methyl or ethyl. Moreover, X represents an
anion as above.
An inorganic carrier supported type strongly basic anion
exchanger having quaternary ammonium groups as exchange groups that
can be used in the present invention means an inorganic carrier that has
had -0(CH2)nNR3X quaternary ammonium groups introduced thereto by
modifying some or all of the -OH surface hydroxyl groups of the
inorganic carrier. Here, R and X are as above, n is generally an
integer from 1 to 6, preferably n = 2. As the inorganic carrier, silica,
alumina, silica-alumina, titania, a zeolite, or the like can be used, it being
preferable to use silica, alumina, or silica-alumina, particularly preferably
silica. Any method can be used as the method of modifying the surface
hydroxyl groups of the inorganic carrier.
As the solid strongly basic anion exchanger having quaternary
ammonium groups as exchange groups, a commercially available one
may be used. In this case, the anion exchanger may also be used as
the transesterification catalyst after being subjected to ion exchange with
27

A0501 VP84/KAN
a desired anionic species in advance as pretreatment.
Moreover, a solid catalyst consisting of a macroreticular or
gel-type organic polymer having bonded thereto heterocyclic groups each
containing at least one nitrogen atom, or an inorganic carrier having
bonded thereto heterocyclic groups each containing at least one nitrogen
atom can also be preferably used as the transesterification catalyst.
Furthermore, a solid catalyst in which some or all of these
nitrogen-containing heterocyclic groups have been converted into a
quaternary salt can be similarly used. Note that a solid catalyst such as
an ion exchanger may also act as a packing in the present invention.
An amount of the catalyst used in the present invention varies
depending on the type of the catalyst used, but in the case of
continuously feeding in a homogeneous catalyst that dissolves in the
reaction liquid under the reaction conditions, the amount used is
generally in a range of from 0.0001 to 50 % by weight, preferably from
0.005 to 20 % by weight, more preferably from 0.01 to 10 % by weight, as
a proportion of the total weight of the cyclic carbonate and the aliphatic
monohydric alcohol fed in as the starting materials. Moreover, in the
case of using a solid catalyst installed in the distillation column, the
catalyst is preferably used in an amount in a range of from 0.01 to 75
vol%, more preferably from 0.05 to 60 vol%, yet more preferably from 0.1
to 60 vol%, based on the empty column volume of the distillation column.
There are no particular limitations on the method of continuously
feeding the cyclic carbonate and the aliphatic monohydric alcohol into
the continuous multi-stage distillation column A constituting the reactive
distillation column in the present invention; any feeding method may be
28

A0501 VP84/KAN
used so long as the cyclic carbonate and the aliphatic monohydric
alcohol can be made to contact the catalyst in a region of at least 5
stages, preferably at least 7 stages, more preferably at least 10 stages,
of the distillation column A. That is, the cyclic carbonate and the
aliphatic monohydric alcohol can be continuously fed in from a required
number of inlets in stages of the continuous multi-stage distillation
column A satisfying the conditions described earlier. Moreover, the
cyclic carbonate and the aliphatic monohydric alcohol may be introduced
into the same stage of the distillation column, or may be introduced into
different stages to one another.
The starting materials may be fed continuously into the distillation
column A in a liquid form, in a gaseous form, or as a mixture of a liquid
and a gas. Other than feeding the starting materials into the distillation
column A in this way, it is also preferable to additionally feed in a
gaseous starting material intermittently or continuously from the lower
portion of the distillation column A. Moreover, another preferable
method is one in which the cyclic carbonate is continuously fed in a liquid
form or a gas / liquid mixed form into a stage of the distillation column A
above the stages in which the catalyst is present, and the aliphatic
monohydric alcohol is continuously fed in a gaseous form and / or a
liquid form into the lower portion of the distillation column A. In this
case, the cyclic carbonate may of course contain the aliphatic
monohydric alcohol.
In the present invention, the starting materials fed in may contain
the product dialkyl carbonate and / or diol. The content thereof is, for
the dialkyl carbonate, generally in a range of from 0 to 40 % by weight,
29

A0501 VP84/KAN
preferably from 0 to 30 % by weight, more preferably from 0 to 20 % by
weight, in terms of the percentage by weight of the dialkyl carbonate in
the aliphatic monohydric alcohol / dialkyl carbonate mixture, and is, for
the diol, generally in a range of from 0 to 10 % by weight, preferably from
0 to 7 % by weight, more preferably from 0 to 5 % by weight, in terms of
the percentage by weight of the diol in the cyclic carbonate / diol mixture.
When carrying out the present reaction industrially, besides fresh
cyclic carbonate and / or aliphatic monohydric alcohol newly introduced
into the reaction system, material having the cyclic carbonate and / or
the aliphatic monohydric alcohol as a main component thereof recovered
from this process and / or another process can also be preferably used
for the starting materials. It is an excellent characteristic feature of the
present invention that this is possible. An example of another process
is a process in which a diary! carbonate is produced from the dialkyl
carbonate and an aromatic monohydroxy compound, the aliphatic
monohydric alcohol being by-produced in this process and recovered.
The recovered by-produced aliphatic monohydric alcohol generally often
contains the dialkyl carbonate, the aromatic monohydroxy compound, an
alkyl aryl ether and so on, and may also contain small amounts of an
alkyl aryl carbonate, the diaryl carbonate and so on. The by-produced
aliphatic monohydric alcohol may be used as is as a starting material in
the present invention, or may be used as a starting material after the
amount of contained material having a higher boiling point than that of
the aliphatic monohydric alcohol has been reduced through distillation or
the like.
A cyclic carbonate preferably used in the present invention is one
30

A0501 VP84/KAN
produced through reaction between, for example, an alkylene oxide such
as ethylene oxide, propylene oxide or styrene oxide and carbon dioxide;
a cyclic carbonate containing small amounts of such starting material
compounds or the like may be used as a starting material in the present
invention.
In the present invention, a ratio between the amounts of the cyclic
carbonate and the aliphatic monohydric alcohol fed into the reactive
distillation column A varies according to the type and amount of the
transesterification catalyst and the reaction conditions, but a molar ratio
of the aliphatic monohydric alcohol to the cyclic carbonate fed in is
generally in a range of from 0.01 to 1000 times. To increase the cyclic
carbonate conversion, it is preferable to feed in the aliphatic monohydric
alcohol in an excess of at least 2 times the number of mols of the cyclic
carbonate. However, if the amount of the aliphatic monohydric alcohol
used is too great, then it is necessary to make the apparatus larger. For
such reasons, the molar ratio of the aliphatic monohydric alcohol to the
cyclic carbonate is preferably in a range of from 2 to 20, more preferably
from 3 to 15, yet more preferably from 5 to 12. Furthermore, if much
unreacted cyclic carbonate remains, then the unreacted cyclic carbonate
may react with the product diol to by-produce oligomers such as a dimer
or a trimer, and hence in the case of industrial implementation, it is
preferable to reduce the amount of unreacted cyclic carbonate remaining
as much as possible. In the process according to the present invention,
even if the above molar ratio is not more than 10, the cyclic carbonate
conversion can be made to be not less than 98%, preferably not less
than 99%, more preferably not less than 99.9%. This is another
31

A0501 VP84/KAN
characteristic feature of the present invention.
In the present invention, preferably not less than approximately 1
ton / hr of a high boiling point reaction mixture AB containing the diol is
continuously produced in the reactive distillation column A, this being fed
into a continuous multi-stage distillation column C, and a column bottom
component CB therefrom being subjected to separation by distillation in a
continuous multi-stage distillation column E, so as to produce not less
than approximately 1 ton / hr of the high-purity diol; the minimum amount
of the cyclic carbonate continuously fed into the reactive distillation
column A to achieve this is generally 1.55 P ton / hr, preferably 1.5 P ton
/ hr, more preferably 1.45 P ton / hr, based on the amount P (ton / hr) of
the high-purity diol to be produced. In a yet more preferable case, this
amount can be made to be less than 1.43 P ton / hr.
There are no particular limitations on the continuous multi-stage
distillation column A for carrying out the reactive distillation process in
the present invention, but the continuous multi-stage distillation column A
is preferably one that enables not only distillation but also reaction to be
carried out at the same time so as to be able to produce preferably not
less than 1.5 ton / hr of the dialkyl carbonate and / or preferably not less
than 1 ton / hr of the diol stably for a prolonged period of time.
In the present invention, a cyclic carbonate and an aliphatic
monohydric alcohol are taken as starting materials, the starting materials
are continuously fed into a continuous multi-stage distillation column A in
which a catalyst is present, reactive distillation is carried out in the
column A, a low boiling point reaction mixture AT containing a produced
dialkyl carbonate and the aliphatic monohydric alcohol is continuously
32

A0501 VP84/KAN
withdrawn from an upper portion of the column A in a gaseous form, a
high boiling point reaction mixture AB containing a produced diol is
continuously withdrawn from a lower portion of the column A in a liquid
form, the high boiling point reaction mixture AB is continuously fed into a
continuous multi-stage distillation column C, material having a lower
boiling point than the diol contained in the high boiling point reaction
mixture AB is distilled off as a column top component CT and / or a side
cut component Cs so as to obtain a column bottom component CB, the
column bottom component CB is continuously fed into a continuous
multi-stage distillation column E, and the diol is obtained as a side cut
component Es from a side cut outlet of the continuous multi-stage
distillation column E, whereby a high-purity diol is produced. The
continuous multi-stage distillation column C thus preferably has a
function of enabling the material having a lower boiling point than that of
the diol contained in the high boiling point reaction mixture AB to be
removed efficiently as the column top component CT and / or the side cut
component Cs.
Moreover, for the continuous multi-stage distillation column C, it is
preferable for it to be devised such that unreacted cyclic carbonate,
which is generally contained in a small amount in the high boiling point
reaction mixture AB, is reacted with the diol (e.g. for a temperature and
residence time required for this reaction to proceed to completion to be
secured). As a result, it can be made to be such that there is
substantially no unreacted cyclic carbonate in the column bottom
component CB from the continuous multi-stage distillation column C,
which is preferable when carrying out the present invention.
33

A0501 VP84/KAN
The continuous multi-stage distillation column E used in the
present invention must have a function of enabling a high-purity diol to
be obtained with a high yield stably for a prolonged period of time from a
large amount of the column bottom component CB, and various conditions
must be simultaneously satisfied to achieve this.
Specifically,
(a) the continuous multi-stage distillation column E comprises a
distillation column comprising a stripping section having a length l_i (cm),
an inside diameter D^ (cm) and an internal with a number of stages ni
thereinside, and an enrichment section having a length l_2 (cm), an inside
diameter D2 (cm) and an internal with a number of stages n2 thereinside,
wherein Li, Di, n-i, L2, D2, and n2 satisfy the following formulae (1) to (9):

400 50 2 3 600 100 2 5 DT (b) the enrichment section of the continuous multi-stage
distillation column E has at least one chimney tray as the internal
installed therein, the chimney tray having installed therein at least two
chimneys each having an opening having a cross-sectional area S (cm2)
satisfying the formula (10):
34

A0501 VP84/KAN
50 and each of the chimneys being such that a height h (cm) from the
opening of the chimney to a gas outlet of the chimney satisfies the
formula (11):
20 (c) a side cut outlet installed for continuously withdrawing the
high-purity diol in a liquid form from the continuous multi-stage
distillation column E is connected to a liquid collecting section of the
chimney tray.
It has been discovered that by subjecting, to separation by
distillation in the continuous multi-stage distillation column E having the
specified structure simultaneously satisfying the above formulae (1) to
(11), the column bottom component CB obtained by using the continuous
multi-stage distillation column C to distill off material having a lower
boiling point than that of the diol from a large amount of the high boiling
point reaction mixture AB produced through a reactive distillation process
between the cyclic carbonate and the aliphatic monohydric alcohol, a
high-purity diol having a purity of preferably not less than 99%, more
preferably not less than 99.9%, can be produced on an industrial scale of
preferably not less than 1 ton / hr, more preferably not less than 2 ton /
hr, stably for a prolonged period of time of, for example, not less than
1000 hours, preferably not less than 3000 hours, more preferably not
less than 5000 hours. The reason why it has become possible to
produce the high-purity diol on an industrial scale with such excellent
effects by implementing the process according to the present invention is
not clear, but this is supposed to be due to a composite effect brought
35

A0501 VP84/KAN
about when the conditions of the above formulae (1) to (11) are combined.
Note that preferable ranges for the respective factors are described
below.
If Li (cm) is less than 400, then the separation efficiency for the
stripping section decreases, and hence the desired separation efficiency
cannot be attained. Moreover, to keep down the equipment cost while
securing the desired separation efficiency, l_i must be made to be not
more than 3000. Furthermore, if L1 is greater than 3000, then the
pressure difference between the top and bottom of the column becomes
too great, and hence prolonged stable operation becomes difficult, and
moreover it becomes necessary to increase the temperature in the lower
portion of the column, and hence side reactions become liable to occur.
A more preferable range for L^ (cm) is 500 1500 being yet more preferable.
If Di (cm) is less than 50, then it is not possible to attain the
desired distillation amount. Moreover, to keep down the equipment cost
while attaining the desired distillation amount, Di must be made to be not
more than 700. A more preferable range for Di (cm) is 100 with 120 If Li / Di is less than 2 or greater than 50, then prolonged stable
operation becomes difficult. A more preferable range for l_i / Di is 3 Li / Di If ni is less than 3, then the separation efficiency for the stripping
section decreases and hence the desired separation efficiency cannot be
attained. Moreover, to keep down the equipment cost while securing the
desired separation efficiency, ni must be made to be not more than 30.
36

A0501 VP84/KAN
Furthermore, if r»i is greater than 30, then the pressure difference
between the top and bottom of the column becomes too great, and hence
prolonged stable operation becomes difficult, and moreover it becomes
necessary to increase the temperature in the lower portion of the column,
and hence side reactions become liable to occur. A more preferable
range for ni is 5 If L2 (cm) is less than 600, then the separation efficiency for the
enrichment section decreases, and hence the desired separation
efficiency cannot be attained. Moreover, to keep down the equipment
cost while securing the desired separation efficiency, L2 must be made to
be not more than 4000. Furthermore, if L2 is greater than 4000, then the
pressure difference between the top and bottom of the column becomes
too great, and hence prolonged stable operation becomes difficult.
Moreover, it becomes necessary to increase the temperature in the lower
portion of the column, and hence side reactions become liable to occur.
A more preferable range for L2 (cm) is 700 2500 being yet more preferable.
If D2 (cm) is less than 100, then it is not possible to attain the
desired distillation amount. Moreover, to keep down the equipment cost
while attaining the desired distillation amount, D2 must be made to be not
more than 1000. A more preferable range for D2 (cm) is 120 with 150 If L2 / D2 is less than 2 or greater than 30, then prolonged stable
operation becomes difficult. A more preferable range for L2 / D2 is 3 » L2 / D2 If n2 is less than 5, then the separation efficiency for the
37

A0501 VP84/KAN
enrichment section decreases and hence the desired separation
efficiency cannot be attained. Moreover, to keep down the equipment
cost while securing the desired separation efficiency, n2 must be made to
be not more than 50. Furthermore, if n2 is greater than 50, then the
pressure difference between the top and bottom of the column becomes
too great, and hence prolonged stable operation becomes difficult.
Moreover, it becomes necessary to increase the temperature in the lower
portion of the column, and hence side reactions become liable to occur.
A more preferable range for n2 is 7 more preferable. Note that in the present invention, at least one
chimney tray must be installed in the enrichment section, and the number
of stages therefor is included in n2 above.
Moreover, for the continuous multi-stage distillation column E of
the present invention, preferably Di The chimney tray installed in the enrichment section of the
continuous multi-stage distillation column E has provided therein at least
two chimneys each having an opening having a cross-sectional area S
(cm2) in the plane of the tray. Moreover, a chimney cover is preferably
installed on an upper opening of each of the chimneys. This chimney
cover plays a role in a gaseous component that rises up from lower
stages flowing sideways at the upper opening (gas outlet) of the chimney,
and moreover plays a role in preventing a liquid component that falls
down from upper stages from falling down directly into the lower stages.
The cross-sectional shape of each of the chimneys may be any of
triangular, square, polygonal, circular, elliptical, star-shaped or the like,
but a square shape or a circular shape is preferably used. Moreover, for
38

A0501 VP84/KAN
each of the chimneys, the cross-sectional shape and area may vary from
an upper portion to a lower portion of the chimney, but is preferably
constant since then manufacture is simple and inexpensive. Moreover,
the at least two chimneys may have different shapes to one another, but
preferably have the same shape as one another.
In the present invention, the cross-sectional area S (cm2) of the
opening (the part of the chimney having the smallest cross section) of
each of the chimneys connected to the chimney tray must satisfy the
following formula (10):
50 If S is less than 50, then a large number of chimneys are required
to attain a predetermined production amount, and hence the equipment
cost becomes high. If S is greater than 2000, then the flow of gas in the
chimney tray stage is prone to becoming ununiform, and hence prolonged
stable operation becomes difficult. A more preferable range for S (cm2)
is 100 Moreover, the height h (cm) from the opening of each of the
chimneys to the gas outlet (a lower end of the upper opening of the
chimney) of that chimney must satisfy the following formula (11);
20 The chimney tray used in the present invention generally has
installed therein a downcomer portion for allowing the liquid component
to fall down into lower stages, and a weir for holding the liquid
component. The height of the weir depends on h, but is generally set to
approximately 5 to 20 cm less than h. Consequently, if h is less than 20,
then the amount of liquid held in the chimney tray becomes low, and
39

A0501 VP84/KAN
hence prolonged stable operation becomes difficult. Moreover, if h is
greater than 100, then the amount of liquid held increases, and hence
the strength of the equipment must be increased, and thus the equipment
cost becomes high, and moreover the residence time of the purified diol
in the column increases, which is undesirable. A more preferable range
for h (cm) is 30 An aperture ratio (a ratio of a total cross-sectional area of the
openings in the chimneys to an area of the chimney tray including the
total cross-sectional area of the openings) of the chimney tray is
preferably in a range of from 5 to 40%. If the aperture ratio is less than
5%, then prolonged stable operation becomes difficult. Moreover, if the
aperture ratio is greater than 40%, then the number of chimneys must be
increased, or each of the chimneys must be made higher, and in either
case the equipment cost becomes high. A more preferable range for the
aperture ratio is from 10 to 30%, with from 15 to 25% being yet more
preferable.
One of the characteristic features of the present invention is that
the at least one chimney tray is installed in the enrichment section (a
portion above an inlet for feeding into the column but below the top of the
column) of the multi-stage distillation column E, and the high-purity diol
is continuously withdrawn in a liquid form from a side cut outlet
connected to the bottom of a liquid collecting portion of the chimney tray.
The number of chimney trays can be made to be two or more if required,
but is generally one. The stage at which the chimney tray is installed
may be at any position in the enrichment section, but is preferably a
stage that is at least three stages from the bottom of the stages in the
40

A0501 VP84/KAN
enrichment section and at least three stages from the top of the stages in
the enrichment section, more preferably a stage that is at least four
stages from the bottom of the stages in the enrichment section and at
least four stages from the top of the stages in the enrichment section, yet
more preferably a stage that is at least five stages from the bottom of the
stages in the enrichment section and at least four stages from the top of
the stages in the enrichment section.
The continuous multi-stage distillation column E of the present
invention is preferably a distillation column having trays and / or
packings as an internal in each of the stripping section and the
enrichment section. The term "internal" used in the present invention
means the part in the distillation column where gas and liquid are
actually brought into contact with one another. Examples of the trays
include a bubble-cap tray, a sieve tray, a ripple tray, a ballast tray, a
valve tray, a counterflow tray, an Unifrax tray, a Superfrac tray, a Maxfrac
tray, a dual flow trays, a grid plate tray, a turbogrid plate tray, a Kittel
tray, or the like. Examples of the packings include random packings
such as a Raschig ring, a Lessing ring, a Pall ring, a Berl saddle, an
Intalox saddle, a Dixon packing, a McMahon packing or Heli-Pak, or
structured packings such as Mellapak, Gempak, Techno-pack, Flexipac, a
Sulzer packing, a Goodroll packing, Glitschgrid or the like. A
multi-stage distillation column having both a tray portion and a portion
packed with packings can also be used. Furthermore, the term "number
of stages ni or n2 of the internal" used in the present invention means the
number of trays in the case of the tray, and the theoretical number of
stages in the case of the packing, ni or n2 in the case of a continuous
41

A0501 VP84/KAN
multi-stage distillation column having both a tray portion and a portion
packed with packings is thus the sum of the number of trays and the
theoretical number of stages.
In the present invention, it is particularly preferable for the
internals in both the stripping section and the enrichment section of the
continuous multi-stage distillation column E to be trays. Furthermore, it
has been discovered that sieve trays each having a sieve portion and a
downcomer portion are particularly good as the tray in terms of the
relationship between performance and equipment cost. It has also been
discovered that each sieve tray preferably has 150 to 1200 holes / m2 in
the sieve portion thereof. A more preferable number of holes is from
200 to 1100 holes / m2, yet more preferably from 250 to 1000 holes / m2.
Moreover, it has been discovered that the cross-sectional area per hole
of each sieve tray is preferably in a range of from 0.5 to 5 cm2. A more
preferable cross-sectional area per hole is from 0.7 to 4 cm2, yet more
preferably from 0.9 to 3 cm2. Furthermore, it has been discovered that
it is particularly preferable if each sieve tray has 150 to 1200 holes / m2
in the sieve portion thereof, and the cross-sectional area per hole is in a
range of from 0.5 to 5 cm2.
An aperture ratio (the ratio of the total cross-sectional area of the
holes in one tray stage to the area of the tray) of each of the sieve trays
in the stripping section of the continuous multi-stage distillation column E
is preferably in a range of from 3 to 25%, more preferably from 3.5 to
22%, yet more preferably from 4 to 20%. Moreover, an aperture ratio
(the ratio of the total cross-sectional area of the holes in one tray stage
to the area of the tray) of each of the sieve trays in the enrichment
42

A0501 VP84/KAN
section of the continuous multi-stage distillation column E is preferably in
a range of from 2 to 20%, more preferably from 3 to 15%, yet more
preferably from 3.5 to 13%. Note that in the present invention, the
chimney tray installed in the enrichment section is counted in the number
of stages, but as described above, the aperture ratio for the chimney tray
is different to the aperture ratio for the sieve trays.
It has been shown that by adding the above conditions to the
continuous multi-stage distillation column E, the object of the present
invention can be attained more easily.
In the present invention, the dialkyl carbonate produced through
the reactive distillation in the continuous multi-stage distillation column A
is continuously withdrawn from the upper portion of the column in a
gaseous form as the low boiling point reaction mixture AT together with
aliphatic monohydric alcohol that has remained unreacted due to
generally being used in excess. Moreover, the high boiling point
reaction mixture AB containing the produced diol is continuously
withdrawn from the lower portion of the column in a liquid form. The
high boiling point reaction mixture AB having the diol as a main
component thereof generally contains 10 to 45 % by weight of the
residual aliphatic monohydric alcohol, a trace of the dialkyl carbonate, a
very small amount (generally not more than 0.2 % by weight) of
unreacted cyclic carbonate, a small amount (generally not more than
0.4 % by weight) of by-products having a lower boiling point than the diol
(a 2-alkoxyethanol etc.), and a small amount (generally not more than
0.4 % by weight) of by-products having a higher boiling point than that of
the diol (e.g. a dialkylene glycol) including catalyst.
43

A0501 VP84/KAN
Material having a lower boiling point than that of the diol (the
aliphatic monohydric alcohol, a trace of the dialkyl carbonate and
by-produced CO2, low boiling point by-products) and a small amount of
the diol in the high boiling point reaction mixture AB continuously fed into
the continuous multi-stage distillation column C are thus continuously
withdrawn as the column top component CT and / or the side cut
component Cs, while the diol containing the catalyst and a small amount
of high boiling point by-products is continuously withdrawn as the column
bottom component CB. In the present invention, the concentration of the
diol in the column bottom component CB is generally not less than 95 %
by weight, preferably not less than 97 % by weight, more preferably not
less than 98 % by weight.
Moreover, in the process of the present invention, a very small
amount (generally not more than 0.2 % by weight) of unreacted cyclic
carbonate fed into the continuous multi-stage distillation column C can
be reacted with the diol, which is present in a large amount in the
continuous multi-stage distillation column C, to produce a dialkylene
glycol, and hence it is easy to make the amount of unreacted cyclic
carbonate present substantially zero; in the present invention, the
column bottom component CB continuously fed into the continuous
multi-stage distillation column E thus generally has substantially no
unreacted cyclic carbonate therein.
Note that, generally, with an objective of obtaining an
ultra-high-purity diol having a further reduced content of an aldehyde
which may be contained in the diol in trace amount, or an
ultra-high-purity diol having a high UV transmissivity, it is also preferable
44

A0501 VP84/KAN
to feed a small amount of water into the lower portion of the continuous
multi-stage distillation column E in accordance with the process
described in Patent Document 9 (Japanese Patent Application Laid-Open
No. 2002-308804) or Patent Document 10 (Japanese Patent Application
Laid-Open No. 2004-131394).
The distillation conditions for the continuous multi-stage
distillation column E used in the present invention vary depending on the
form of the internal in the distillation column and the number of stages,
the type, composition and amount of the column bottom component CB of
the distillation column C fed in, the purity of the diol required, and so on.
The column bottom temperature is generally preferably a specified
temperature in a range of from 110 to 210 °C. A more preferable column
bottom temperature range is from 120 to 190 °C, yet more preferably
from 130 to 170 °C. The column bottom pressure varies depending on
the composition in the column and the column bottom temperature used,
but is generally in a range of from 8000 to 40000 Pa, preferably 10000 to
33000 Pa, more preferably 12000 to 27000 Pa.
Moreover, the reflux ratio for the continuous multi-stage distillation
column E is preferably in a range of from 6 to 50, more preferably from 8
to 45, yet more preferably from 10 to 30.
In the present invention, a column top component ET from the
continuous multi-stage distillation column E comprises a small amount of
the diol (generally not more than 10 % by weight of the diol fed in);
moreover, in the case that water is fed into the continuous multi-stage
distillation column E, almost all of the water fed in is withdrawn in the
column top component Ey. The column top component ET is generally
45

A0501 VP84/KAN
recycled into the continuous multi-stage distillation column C, and then
fed back into the continuous multi-stage distillation column E as some of
the column bottom component CB, and thus recovered as high-purity diol.
Moreover, a column bottom component EB from the continuous
multi-stage distillation column E contains high boiling point by-products
and catalyst component containing a small amount of the diol. The side
cut component Es from the continuous multi-stage distillation column E
generally contains not less than 99%, preferably not less than 99.9%,
more preferably not less than 99.99%, of the high-purity diol. That is, in
the present invention, the content in the side cut component Es of
impurities (a dialkylene glycol etc.) having a higher boiling point than that
of the diol can generally easily be made to be not more than 1 % by
weight, preferably not more than 0.1 % by weight, more preferably not
more than 0.01 % by weight. Moreover, in a preferable embodiment of
the present invention, the reaction is carried out using starting materials
and a catalyst not containing a halogen, and hence the produced diol can
be made to not contain a halogen at all. In the present invention, a diol
having a halogen content of not more than 0.1 ppm, preferably not more
than 1 ppb, can thus be easily produced.
That is, in the present invention, a high-purity diol having a
content of impurities having a higher boiling point than that of the diol
such as a dialkylene glycol of not more than 200 ppm, and a halogen
content of not more 0.1 ppm can be easily produced, preferably a
high-purity diol having a content of impurities having a higher boiling
point than that of the diol such as a dialkylene glycol of not more than
100 ppm, and a halogen content of not more 1 ppb can be easily
46

A0501 VP84/KAN
produced.
In the present invention, the reaction yield and the purification
yield are thus high, and hence the high-purity diol can be produced with
a high yield of generally not less than 97%, preferably not less than 98%,
more preferably not less than 99%, based on the cyclic carbonate used.
The material constituting each of the continuous multi-stage
distillation columns A, C and E used in the present invention is generally
a metallic material such as carbon steel or stainless steel. In terms of
the quality of the dialkyl carbonate and diol to be produced, stainless
steel is preferable.
EXAMPLES
Although the following is a more detailed description of the
present invention through examples, the present invention is not limited
to the following examples. Note that the halogen content was measured
using ion chromatography.
Example 1:
A continuous multi-stage distillation column E as shown in FIG. 1
having l_i = 850 cm, Di = 160 cm, U / D^ = 5.3, n^ = 8, L2 = 1000 cm, D2
= 200 cm, L_2 / D2 = 5, and n2 = 11, and having one chimney tray stage
installed at the 5th stage from the top of the enrichment section stages
was used. In this example, sieve trays (cross-sectional area per hole =
approximately 1.3 cm2) were used in both the stripping section and the
enrichment section as the internal excluding the chimney tray. In the
stripping section, the number of holes in each of the sieve trays was
approximately 300 to 370 / m2, and the aperture ratio was in a range of
47

A0501 VP84/KAN
from 4 to 5%. Moreover, in the enrichment section, the number of holes
in each of the sieve trays was approximately 300 to 450 / m2, and the
aperture ratio was in a range of from 3 to 4%. The chimney tray had
twelve chimneys therein, each of the chimneys having S = approximately
500 cm2 and h = 55 cm, and the aperture ratio being in a range of from
15 to 20%. The chimney tray had a downcomer portion, the weir height
being 40 cm.
A starting material containing ethylene carbonate (EC) and
methanol (MeOH) (molar ratio MeOH / EC = 8.4) and a catalyst (KOH in
ethylene glycol subjected to thermal dehydration treatment; K
concentration 0.1 % by weight based on EC) was continuously fed into a
continuous multi-stage distillation column A, and reactive distillation was
carried out, whereby 3.205 ton / hr of a column bottom component AB
was continuously withdrawn. The ethylene carbonate conversion was
100%, and the ethylene glycol selectivity was 99.8%. The column
bottom component AB, which contained 0.99 ton / hr of methanol, 0.001
ton / hr of dimethyl carbonate, 0.009 ton / hr of 2-methoxyethanol, 2.186
ton / hr of ethylene glycol, and 0.019 ton / hr of diethylene glycol and
catalyst component, was continuously fed into a continuous multi-stage
distillation column C from an inlet. This inlet was installed between the
trays in the 9th and 10th stages from the bottom of the continuous
multi-stage distillation column C. Separate to this, 0.155 ton / hr of a
column top component ET (0.137 ton / hr of ethylene glycol, 0.019 ton /
hr of water) from the continuous multi-stage distillation column E was
continuously fed into the continuous multi-stage distillation column C via
a reboiler at the bottom of the continuous multi-stage distillation column
48

A0501 VP84/KAN
C.
A column top component CT containing 0.968 ton / hr of methanol,
0.001 ton / hr of dimethyl carbonate, and 0.019 ton / hr of water, a side
cut component Cs containing 0.022 ton / hr of methanol, 0.0093 ton / hr
of 2-methoxyethanol, and 0.003 ton / hr of ethylene glycol, and a column
bottom component CB containing 2.32 ton / hr of ethylene glycol, and
0.019 ton / hr of diethylene glycol, catalyst component and high boiling
point by-products were continuously withdrawn from the continuous
multi-stage distillation column C.
2.339 Ton / hr of the column bottom component CB was
continuously fed into the continuous multi-stage distillation column E
from an inlet 1 installed between the 8th and 9th stages from the bottom
of the column. 0.019 Ton / hr of water having an oxygen concentration
of not more than 10 ppm was fed into the continuous multi-stage
distillation column E via a reboiler 7 from an inlet 5 in the bottom of the
column. The continuous multi-stage distillation column E was operated
continuously with a column bottom temperature of approximately 149 °C,
a column bottom pressure of approximately 14600 Pa, and a reflux ratio
of 11.
It was possible to attain stable steady state operation after 24
hours. A column top component ET continuously withdrawn from the top
2 of the continuous multi-stage distillation column E at 0.155 ton / hr
contained 0.136 ton / hr of ethylene glycol and 0.019 ton / hr of water.
This column top component ET was recycled back into the continuous
multi-stage distillation column C. A column bottom component EB
continuously withdrawn from the bottom 3 of the continuous multi-stage
49

A0501 VP84/KAN
distillation column E at 0.04 ton / hr contained 0.02 ton / hr of ethylene
glycol, and 0.02 ton / hr of diethylene glycol, catalyst component and
high boiling point by-products. The purity of ethylene glycol in a side
cut component Es continuously withdrawn at 2.164 ton / hr from a side
cut 4 of the continuous multi-stage distillation column E was not less
than 99.99%, the content of high boiling point impurities such as
diethylene glycol being not more than 10 ppm, and the halogen content
being outside the detection limit, i.e. not more than 1 ppb.
The high-purity ethylene glycol yield based on the ethylene
carbonate was 98.6%.
Prolonged continuous operation was carried out under these
conditions. After 500 hours, 2000 hours, 4000 hours, 5000 hours, and
6000 hours, the produced amounts of ethylene glycol per hour were
2.162 ton, 2.162 ton, 2.162 ton, 2.162 ton, and 2.162 ton, and hence
operation was very stable. The purity of the ethylene glycol was not
less than 99.99% in each case, and the halogen content was outside the
detection limit, i.e. not more than 1 ppb. Moreover, the aldehyde
content measured using the method of Patent Document 15 (Japanese
Patent Application Laid-Open No. 2003-342209) was not more than 0.2
ppm, and the UV transmissivity at 220 nm was 90%.
Example 2:
High-purity ethylene glycol was produced using the same
continuous multi-stage distillation column E as in Example 1 and a
similar process.
2.472 Ton / hr of the column bottom component CB continuously
50

A0501 VP84/KAN
withdrawn from the continuous multi-stage distillation column C (2.439
Ton / hr of ethylene glycol, and 0.033 ton / hr of diethylene glycol,
catalyst component and high boiling point by-products) was continuously
fed into the continuous multi-stage distillation column E from the inlet 1.
0.022 Ton / hr of water having an oxygen concentration of not
more than 10 ppm was fed into the continuous multi-stage distillation
column E via the reboiler 7 from the inlet 5 in the bottom of the column.
The continuous multi-stage distillation column E was operated
continuously with a column bottom temperature of approximately 162 °C,
a column bottom pressure of approximately 17300 Pa, and a reflux ratio
of 12.
It was possible to attain stable steady state operation after 24
hours. The column top component Ex continuously withdrawn from the
top 2 of the continuous multi-stage distillation column E at 0.192 ton / hr
contained 0.17 ton / hr of ethylene glycol and 0.022 ton / hr of water.
This column top component Ej was recycled back into the continuous
multi-stage distillation column C. The column bottom component EB
continuously withdrawn from the bottom 3 of the continuous multi-stage
distillation column E at 0.055 ton / hr contained 0.015 ton / hr of ethylene
glycol, and 0.04 ton / hr of diethylene glycol, catalyst component and
high boiling point by-products. The purity of ethylene glycol in the side
cut component Es continuously withdrawn at 2.29 ton / hr from the side
cut 4 of the continuous multi-stage distillation column E was not less
than 99.99%, the content of high boiling point impurities such as
diethylene glycol being not more than 10 ppm, and the halogen content
being outside the detection limit, i.e. not more than 1 ppb.
51

A0501 VP84/KAN
The high-purity ethylene glycol yield based on the ethylene
carbonate was 98.5%.
Prolonged continuous operation was carried out under these
conditions. After 1000 hours, 2000 hours, 3000 hours, and 5000 hours,
the produced amounts of ethylene glycol per hour were 2.29 ton, 2.29 ton,
2.29 ton, and 2.29 ton, and hence operation was very stable. The purity
of the ethylene glycol was not less than 99.99% in each case, and the
halogen content was outside the detection limit, i.e. not more than 1 ppb.
Moreover, the aldehyde content was not more than 0.2 ppm, and the UV
transmissivity at 220 nm was 90%.
Example 3:
A continuous multi-stage distillation column E very similar to that
used in Example 1 was used. However, in the enrichment section, the
number of holes in each of the sieve trays was approximately 400 to
450/m2, and the aperture ratio was in a range of from 5 to 6%.
2.925 Ton / hr of the column bottom component CB continuously
withdrawn from the continuous multi-stage distillation column C (2.877
ton / hr of ethylene glycol, and 0.048 ton / hr of diethylene glycol,
catalyst component and high boiling point by-products) was continuously
fed into the continuous multi-stage distillation column E from the inlet 1.
0.026 Ton / hr of water having an oxygen concentration of not
more than 10 ppm was fed into the continuous multi-stage distillation
column E via the reboiler 7 from the inlet 5 in the bottom of the column.
The continuous multi-stage distillation column E was operated
continuously with a column bottom temperature of approximately 155 °C,
52

A0501 VP84/KAN
a column bottom pressure of approximately 18000 Pa, and a reflux ratio
of 10.
It was possible to attain stable steady state operation after 24
hours. The column top component ET continuously withdrawn from the
top 2 of the continuous multi-stage distillation column E at 0.233 ton / hr
contained 0.207 ton / hr of ethylene glycol and 0.026 ton / hr of water.
This column top component ET was recycled back into the continuous
multi-stage distillation column C. The column bottom component EB
continuously withdrawn from the bottom 3 of the continuous multi-stage
distillation column E at 0.07 ton / hr contained 0.02 ton / hr of ethylene
glycol, and 0.05 ton / hr of diethylene glycol, catalyst component and
high boiling point by-products. The purity of ethylene glycol in the side
cut component Es continuously withdrawn at 2.648 ton / hr from the side
cut 4 of the continuous multi-stage distillation column E was not less
than 99.99%, the content of high boiling point impurities such as
diethylene glycol being not more than 10 ppm, and the halogen content
being outside the detection limit, i.e. not more than 1 ppb.
The high-purity ethylene glycol yield based on the ethylene
carbonate was 98.7%.
Prolonged continuous operation was carried out under these
conditions. After 1000 hours, 2000 hours, and 3000 hours, the
produced amounts of ethylene glycol per hour were 2.648 ton, 2.648 ton,
and 2.648 ton, and hence operation was very stable. The purity of the
ethylene glycol was not less than 99.99% in each case, and the halogen
content was outside the detection limit, i.e. not more than 1 ppb.
Moreover, the aldehyde content was not more than 0.2 ppm, and the UV
53

A0501 VP84/KAN
transmissivity at 220 nm was 90%.
Example 4:
A continuous multi-stage distillation column E very similar to that
used in Example 1 was used. However, in the stripping section, the
number of holes in each of the sieve trays was approximately 650 to
750/m2, and the aperture ratio was in a range of from 8 to 10%, and in
the enrichment section, the number of holes in each of the sieve trays
was approximately 500 to 650 / m2, and the aperture ratio was in a range
of from 6 to 8%.
5.852 Ton / hr of the column bottom component CB continuously
withdrawn from the continuous multi-stage distillation column C (5.754
ton / hr of ethylene glycol, and 0.098 ton / hr of diethylene glycol,
catalyst component and high boiling point by-products) was continuously
fed into the continuous multi-stage distillation column E from the inlet 1.
0.05 Ton / hr of water having an oxygen concentration of not more
than 10 ppm was fed into the continuous multi-stage distillation column E
via the reboiler 7 from the inlet 5 in the bottom of the column. The
continuous multi-stage distillation column E was operated continuously
with a column bottom temperature of approximately 160 °C, a column
bottom pressure of approximately 21300 Pa, and a reflux ratio of 13.
It was possible to attain stable steady state operation after 24
hours. The column top component ET continuously withdrawn from the
top 2 of the continuous multi-stage distillation column E at 0.45 ton / hr
contained 0.4 ton / hr of ethylene glycol and 0.05 ton / hr of water. This
column top component ET was recycled back into the continuous
54

A0501 VP84/KAN
multi-stage distillation column C. The column bottom component EB
continuously withdrawn from the bottom 3 of the continuous multi-stage
distillation column E at 0.2 ton / hr contained 0.1 ton / hr of ethylene
glycol, and 0.1 ton / hr of diethylene glycol, catalyst component and high
boiling point by-products. The purity of ethylene glycol in the side cut
component Es continuously withdrawn at 5.202 ton / hr from the side cut
4 of the continuous multi-stage distillation column E was not less than
99.99%, the content of high boiling point impurities such as diethylene
glycol being not more than 10 ppm, and the halogen content being
outside the detection limit, i.e. not more than 1 ppb.
The high-purity ethylene glycol yield based on the ethylene
carbonate was 97.6%.
Prolonged continuous operation was carried out under these
conditions. After 500 hours, 1000 hours, and 1500 hours, the produced
amounts of ethylene glycol per hour were 5.202 ton, 5.202 ton, and 5.202
ton, and hence operation was very stable. The purity of the ethylene
glycol was not less than 99.99% in each case, and the halogen content
was outside the detection limit, i.e. not more than 1 ppb. Moreover, the
aldehyde content was not more than 0.2 ppm, and the UV transmissivity
at 220 nm was 90%.
Industrial Applicability
According to the present invention, it has been discovered that,
from out of a dialkyl carbonate and a diol produced through a reactive
distillation system from a cyclic carbonate and an aliphatic monohydric
alcohol, a high-purity diol having a purity of not less than 97%, preferably
55

A0501 VP84/KAN
not less than 99%, more preferably not less than 99.9%, a content of
high boiling point impurities including a dialkylene glycol of preferably
not more than 200 ppm, more preferably not more than 100 ppm, yet
more preferably not more than 10 ppm, and a halogen content of
preferably not more than 0.1 ppm, more preferably not more than 1 ppb,
can be obtained on an industrial scale of not less than 1 ton / hr,
preferably not less than 2 ton / hr, more preferably not less than 3 ton /
hr, with a high yield stably for a prolonged period of time of not less than
1000 hours, preferably not less than 3000 hours, more preferably not
less than 5000 hours. This high-purity diol (e.g. high-purity ethylene
glycol) has a higher purity than such a diol industrially produced using an
existing production process (e.g. an ethylene oxide hydration process),
and hence is useful as a starting material for a high-quality polyester (e.g.
PET fiber or PET resin).
56

A0501 VP84/KAN
CLAIMS
We claim:
1. An industrial process for the production of a high-purity diol
in which a high-purity diol is produced by taking a cyclic carbonate and
an aliphatic monohydric alcohol as starting materials, continuously
feeding the starting materials into a continuous multi-stage distillation
column A in which a catalyst is present, carrying out reactive distillation
in said column A, continuously withdrawing a low boiling point reaction
mixture AT containing a produced dialkyl carbonate and the aliphatic
monohydric alcohol from an upper portion of the column A in a gaseous
form, continuously withdrawing a high boiling point reaction mixture AB
containing a produced diol from a lower portion of the column A in a
liquid form, continuously feeding said high boiling point reaction mixture
AB into a continuous multi-stage distillation column C, distilling off
material having a lower boiling point than the diol contained in said high
boiling point reaction mixture AB as a column top component CT and / or
a side cut component Cs so as to obtain a column bottom component CB,
continuously feeding the column bottom component CB into a continuous
multi-stage distillation column E, and obtaining the diol as a side cut
component Es from a side cut outlet of the continuous multi-stage
distillation column E, wherein:
(a) said continuous multi-stage distillation column E comprises a
distillation column comprising a stripping section having a length L-i (cm),
an inside diameter Di (cm) and an internal with a number of stages ni
thereinside, and an enrichment section having a length l_2 (cm), an inside
diameter D2 (cm) and an internal with a number of stages n2 thereinside,
57

A0501 VP84/KAN
wherein U, Du ni, L2, D2, and n2 satisfy the following formulae (1) to (9):

400 50 2 3 600 100 2 5 Di (b) the enrichment section of said continuous multi-stage
distillation column E has at least one chimney tray as an internal
installed therein, said chimney tray having installed therein at least two
chimneys each having an opening having a cross-sectional area S (cm2)
satisfying the formula (10):
50 and each of the chimneys being such that a height h (cm) from the
opening of the chimney to a gas outlet of the chimney satisfies the
formula (11):
20 (c) the diol is continuously withdrawn in a liquid form from the side
cut outlet, which is connected to a liquid collecting section of said
chimney tray of said continuous multi-stage distillation column E.
2. The process according to Claim 1, wherein a produced
amount of the high-purity diol is not less than 1 ton / hr.
58

A0501 VP84/KAN
3. The process according to Claim 1 or 2, wherein Li, Di, U /
D-i, n-i, L2, D2, L2 / D2, and n2 for said continuous multi-stage distillation
column E satisfy 500 D1 4. The process according to any one of Claims 1 to 3, wherein
an internal excluding the chimney tray in each of the stripping section
and the enrichment section of said continuous multi-stage distillation
column E is a tray and / or a packing.
5. The process according to Claim 4, wherein the internal
excluding the chimney tray in each of the stripping section and the
enrichment section of said continuous multi-stage distillation column E is
the tray.

6. The process according to Claim 5, wherein said tray is a
sieve tray.
7. The process according to Claim 6, wherein said sieve tray
has 150 to 1200 holes / m2 in a sieve portion thereof, and a
cross-sectional area per hole in a range of from 0.5 to 5 cm2.
8. The process according to Claim 6 or 7, wherein said sieve
tray has 200 to 1100 holes / m2 in a sieve portion thereof, and a
59

A0501 VP84/KAN
cross-sectional area per hole in a range of from 0.7 to 4 cm2.
9. The process according to any one of Claims 6 to 8, wherein
said sieve tray has 250 to 1000 holes / m2 in a sieve portion thereof, and
a cross-sectional area per hole in a range of from 0.9 to 3 cm2.
10. The process according to any one of Claims 6 to 9, wherein
an aperture ratio (a ratio of a total cross-sectional area of the hole in one
tray stage to an area of the tray) of said sieve tray in the stripping
section of said continuous multi-stage distillation column E is in a range
of from 3 to 25%.
11. The process according to any one of Claims 6 to 10,
wherein an aperture ratio (a ratio of a total cross-sectional area of the
hole in one tray stage to an area of the tray) of said sieve trays in the
enrichment of said continuous multi-stage distillation column E is in a
range of from 2 to 20%.

12. The process according to any one of Claims 1 to 11,
wherein an aperture ratio (a ratio of a total cross-sectional area of the
opening in the chimney to an area of the chimney tray including the total
cross-sectional area of the opening) of the chimney tray is in a range of
from 5 to 40%.
13. The process according to any one of Claims 1 to 12,
wherein a column bottom temperature of said continuous multi-stage
60

A0501 VP84/KAN
distillation column E is in a range of from 110 to 210 °C.
14. The process according to any one of Claims 1 to 13,
wherein a reflux ratio of said continuous multi-stage distillation column E
is in a range of from 6 to 100.
15. The process according to any one of Claims 1 to 14,
wherein a purity of the diol in said side cut component Es is not less than
99%.
16. The process according to any one of Claims 1 to 15,
wherein a purity of the diol in said side cut component Es is not less than
99.9%.

17. A high-purity diol produced by the process according to any
one of Claims 1 to 16, which comprises a content of high boiling point
impurities such as a dialkylene glycol of not more than 200 ppm, and a
halogen content of not more than 0.1 ppm.
18. A high-purity diol produced by the process according to any
one of Claims 1 to 16, which comprises a content of high boiling point
impurities such as a dialkylene glycol of not more than 100 ppm, and a
halogen content of not more than 1 ppb.
19. A continuous multi-stage distillation column being a
continuous multi-stage distillation column E for producing a high-purity
61

A0501 VP84/KAN
diol by taking a cyclic carbonate and an aliphatic monohydric alcohol as
starting materials, continuously feeding the starting materials into a
continuous multi-stage distillation column A in which a catalyst is present,
carrying out reactive distillation in said column A, continuously
withdrawing a low boiling point reaction mixture AT containing a produced
dialkyl carbonate and the aliphatic monohydric alcohol from an upper
portion of said column A in a gaseous form, continuously withdrawing a
high boiling point reaction mixture AB containing a produced diol from a
lower portion of said column A in a liquid form, continuously feeding said
high boiling point reaction mixture AB into the continuous multi-stage
distillation column C, distilling off material having a lower boiling point
than the diol contained in said high boiling point reaction mixture AB as a
column top component CT and / or a side cut component Cs so as to
obtain a column bottom component CB, continuously feeding the column
bottom component CB into said continuous multi-stage distillation column
E, and obtaining the diol as a side cut component Es from a side cut
outlet of the continuous multi-stage distillation column E, wherein:

62
(a) said continuous multi-stage distillation column E comprises a
distillation column comprising a stripping section having a length l_i (cm),
an inside diameter D-i (cm) and an internal with a number of stages n-i
thereinside, and an enrichment section having a length L2 (cm), an inside
diameter D2 (cm) and an internal with a number of stages n2 thereinside,
wherein L^ Di, ni, L2> D2, and n2 satisfy the following formulae (1) to (9):

A0501 VP84/KAN

(b) the enrichment section of said continuous multi-stage
distillation column E has at least one chimney tray as an internal
installed therein, said chimney tray having installed therein at least two
chimneys each having an opening having a cross-sectional area S (cm2)
satisfying the formula (10):
50 and each of the chimneys being such that a height h (cm) from the
opening of the chimney to a gas outlet of the chimney satisfies the
formula (11):
20 (c) the side cut outlet installed for continuously withdrawing the
high-purity diol in a liquid form from said continuous multi-stage
distillation column E is connected to a liquid collecting section of said
chimney tray.
20. The continuous multi-stage distillation column according to
Claim 19, wherein l_i, Di, Li / D1r n^ L2, D2, L2 / D2, and n2 satisfy 500 Li 120 63

A0501 VP84/KAN
21. The continuous multi-stage distillation column according to
Claim 19 or 20, wherein an internal excluding the chimney tray in each of
the stripping section and the enrichment section is a tray and / or a
packing.
22. The continuous multi-stage distillation column according to
Claim 21, wherein the internal excluding the chimney tray in each of the
stripping section and the enrichment section is the tray.
23. The continuous multi-stage distillation column according to
Claim 22, wherein said tray is a sieve tray.
24. The continuous multi-stage distillation column according to
Claim 23, wherein said sieve trays has 150 to 1200 holes/m2 in a sieve
portion thereof, and a cross-sectional area per hole in a range of from
0.5 to 5 cm2.

25. The continuous multi-stage distillation column according to
Claim 23 or 24, wherein said sieve trays has 200 to 1100 holes/m2 in a
sieve portion thereof, and a cross-sectional area per hole in a range of
from 0.7 to 4 cm2.
26. The continuous multi-stage distillation column according to
any one of Claims 23 to 25, wherein said sieve trays has 250 to 1000
holes / m2 in a sieve portion thereof, and a cross-sectional area per hole
in a range of from 0.9 to 3 cm2.
64

A0501 VP84/KAN
27. The continuous multi-stage distillation column according to
any one of Claims 23 to 26, wherein an aperture ratio (a ratio of a total
cross-sectional area of the hole in one tray stage to an area of the tray)
5 of said sieve tray in the stripping section is in a range of from 3 to 25%.
28. The continuous multi-stage distillation column according to
any one of Claims 23 to 27, wherein an aperture ratio (a ratio of a total
cross-sectional area of the hole in one tray stage to an area of the tray)
10 of said sieve tray in the enrichment section is in a range of from 2 to
20%.
29. The continuous multi-stage distillation column according to
any one of Claims 23 to 28, wherein an aperture ratio (a ratio of a total
65
15 cross-sectional area of the opening in the chimney to an area of the
chimney tray including the total cross-sectional area of the opening) of
the chimney tray is in a range of from 5 to 40%.

It is an object of the present invention to provide a specific
apparatus and process for producing a high-purity diol by taking a cyclic
carbonate and an aliphatic monohydric alcohol as starting materials,
continuously feeding the starting materials into a continuous multi-stage
distillation column A in which a catalyst is present, carrying out reactive
distillation in the column A, continuously withdrawing a low boiling point
reaction mixture AT containing a produced dialkyl carbonate and the
aliphatic monohydric alcohol from an upper portion of the column A in a
gaseous form, continuously withdrawing a high boiling point reaction
mixture AB containing a produced diol from a lower portion of the column
A in a liquid form, continuously feeding the high boiling point reaction
mixture AB into a continuous multi-stage distillation column C, distilling
off material having a lower boiling point than that of the diol contained in
the high boiling point reaction mixture AB as a column top component CT
and / or a side cut component Cs so as to obtain a column bottom
component CB, continuously feeding the column bottom component CB
into a continuous multi-stage distillation column E, and obtaining the diol
as a side cut component Es from a side cut outlet of the continuous
multi-stage distillation column E. Moreover, it is an object to thus
provide a specific industrial apparatus and industrial production process
that are inexpensive and, for example, enable the high-purity diol to be
produced in an amount of not less than 1 ton / hr stably for a prolonged
period of time (e.g. not less than 1000 hours, preferably not less than
3000 hours, more preferably not less than 5000 hours). The above
objects can be attained by using a continuous multi-stage distillation
column E having a specified structure, and withdrawing a liquid
component from the side cut outlet, which is installed at the bottom of a
chimney tray having a specified structure installed in an enrichment section of the continuous multi-stage distillation column E.


Documents:

00942-kolnp-2008-abstract.pdf

00942-kolnp-2008-claims.pdf

00942-kolnp-2008-correspondence others.pdf

00942-kolnp-2008-description complete.pdf

00942-kolnp-2008-drawings.pdf

00942-kolnp-2008-form 1.pdf

00942-kolnp-2008-form 2.pdf

00942-kolnp-2008-form 3.pdf

00942-kolnp-2008-form 5.pdf

00942-kolnp-2008-gpa.pdf

00942-kolnp-2008-international publication.pdf

00942-kolnp-2008-international search report.pdf

00942-kolnp-2008-pct priority document notification.pdf

00942-kolnp-2008-pct request form.pdf

00942-kolnp-2008-translated copy of priority document.pdf

942-KOLNP-2008-ABSTRACT 1.1.pdf

942-KOLNP-2008-AMANDED CLAIMS.pdf

942-KOLNP-2008-CORRESPONDENCE OTHERS 1.1.pdf

942-KOLNP-2008-CORRESPONDENCE-1.2.pdf

942-kolnp-2008-correspondence-1.3.pdf

942-KOLNP-2008-DESCRIPTION (COMPLETE) 1.1.pdf

942-KOLNP-2008-DRAWINGS 1.1.pdf

942-kolnp-2008-examination report.pdf

942-KOLNP-2008-FORM 1 1.1.pdf

942-kolnp-2008-form 18-1.1.pdf

942-kolnp-2008-form 18.pdf

942-KOLNP-2008-FORM 2 1.1.pdf

942-KOLNP-2008-FORM 3 1.1.pdf

942-kolnp-2008-form 3-1.2.pdf

942-kolnp-2008-form 5.pdf

942-KOLNP-2008-FORM-27.pdf

942-kolnp-2008-gpa.pdf

942-kolnp-2008-granted-abstract.pdf

942-kolnp-2008-granted-claims.pdf

942-kolnp-2008-granted-description (complete).pdf

942-kolnp-2008-granted-drawings.pdf

942-kolnp-2008-granted-form 1.pdf

942-kolnp-2008-granted-form 2.pdf

942-kolnp-2008-granted-specification.pdf

942-KOLNP-2008-INTERNATIONAL EXM REPORT.pdf

942-KOLNP-2008-OTHERS 1.1.pdf

942-kolnp-2008-others-1.2.pdf

942-KOLNP-2008-OTHERS.pdf

942-KOLNP-2008-PETITION UNDER RULE 137.pdf

942-kolnp-2008-reply to examination report-1.1.pdf

942-KOLNP-2008-REPLY TO EXAMINATION REPORT.pdf

942-kolnp-2008-translated copy of priority document.pdf

abstract-00942-kolnp-2008.jpg


Patent Number 246128
Indian Patent Application Number 942/KOLNP/2008
PG Journal Number 07/2011
Publication Date 18-Feb-2011
Grant Date 15-Feb-2011
Date of Filing 03-Mar-2008
Name of Patentee ASAHI KASEI CHEMICALS CORPORATION
Applicant Address 1-2, YURAKU-CHO 1-CHOME, CHIYODA-KU, TOKYO
Inventors:
# Inventor's Name Inventor's Address
1 HIROSHI HACHIYA 1-2, YURAKU-CHO 1-CHOME, CHIYODA-KU, TOKYO 100-8440
2 KAZUHIKO MATSUZAKI 1-2, YURAKU-CHO 1-CHOME, CHIYODA-KU, TOKYO 100-8440
3 SHINSUKE FUKUOKA 1-2, YURAKU-CHO 1-CHOME, CHIYODA-KU, TOKYO 100-8440
4 HIRONORI MIYAJI 1-2, YURAKU-CHO 1-CHOME, CHIYODA-KU, TOKYO 100-8440
PCT International Classification Number C07C 27/02,B01D 3/14
PCT International Application Number PCT/JP2006/326228
PCT International Filing date 2006-12-28
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2006-002711 2006-01-10 Japan