U.S. patent application number 13/832363 was filed with the patent office on 2013-08-29 for process for the manufacture of dichloropropanol.
This patent application is currently assigned to SOLVAY SA. The applicant listed for this patent is SOLVAY SA. Invention is credited to Dominique BALTHASART, Patrick GILBEAU, Philippe KRAFFT, Maurizio PAGANIN.
Application Number | 20130225843 13/832363 |
Document ID | / |
Family ID | 38608894 |
Filed Date | 2013-08-29 |
United States Patent
Application |
20130225843 |
Kind Code |
A1 |
KRAFFT; Philippe ; et
al. |
August 29, 2013 |
PROCESS FOR THE MANUFACTURE OF DICHLOROPROPANOL
Abstract
A process for manufacturing dichloropropanol in which glycerol
and/or monochloropropanediol are reacted with hydrogen chloride, in
a liquid reaction medium, which is in contact with a gaseous phase,
in at least two reactors arranged in a loop, and under a partial
pressure of hydrogen chloride in the first reactor which is greater
than the partial pressure of hydrogen chloride in the second
reactor. This process is suitable for recovering dichloropropanol
free from hydrogen chloride and the recovered dichloropropanol may
be used in subsequent reactions while avoiding overconsumption of
basic agent and loss of recoverable hydrogen chloride, and
corrosion during transfer and storage of dichloropropanol will be
limited.
Inventors: |
KRAFFT; Philippe; (Rhode
Saint Genese, BE) ; GILBEAU; Patrick;
(Braine-le-Comte, BE) ; BALTHASART; Dominique;
(Brussels, BE) ; PAGANIN; Maurizio; (Brussels,
BE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SOLVAY SA; |
|
|
US |
|
|
Assignee: |
SOLVAY SA
Brussels
BE
|
Family ID: |
38608894 |
Appl. No.: |
13/832363 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12529778 |
Sep 3, 2009 |
8471074 |
|
|
PCT/EP2008/052972 |
Mar 13, 2008 |
|
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13832363 |
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61013707 |
Dec 14, 2007 |
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Current U.S.
Class: |
549/518 ;
568/844 |
Current CPC
Class: |
C07C 29/62 20130101;
C07C 29/82 20130101; C07C 29/62 20130101; C07C 29/82 20130101; C07C
29/86 20130101; C07C 31/36 20130101; C07C 29/86 20130101; C07C
31/36 20130101; C07C 31/36 20130101 |
Class at
Publication: |
549/518 ;
568/844 |
International
Class: |
C07C 29/62 20060101
C07C029/62 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2007 |
FR |
0753837 |
Claims
1. A process for manufacturing dichloropropanol wherein glycerol
and/or monochloropropanediol are reacted with hydrogen chloride, in
a liquid reaction medium, which is in contact with a gaseous phase,
in at least two reactors arranged in a loop, and under a partial
pressure of hydrogen chloride in the first reactor which is greater
than the partial pressure of hydrogen chloride in the second
reactor.
2. The process according to claim 1, comprising at least two
separation operations, including one in at least one evaporator in
which the value of the partial pressure of hydrogen chloride is
between the partial pressure of hydrogen chloride in the second
reactor and the partial pressure of hydrogen chloride in the first
reactor and including another in at least one distillation column ,
according to which: the first reactor is supplied with a first gas
flow containing hydrogen chloride and the second reactor with a
first liquid flow containing glycerol and optionally water and
hydrogen chloride, and a second liquid flow containing a catalyst;
drawn off from the first reactor is a third liquid flow and the
evaporator is supplied with this third liquid flow; drawn off from
the evaporator is a second gas flow in which the weight ratio of
hydrogen chloride with respect to water is greater than that of the
azeotropic water/hydrogen chloride composition at total pressure in
the evaporator and the second reactor is supplied with this second
gas flow, drawn off from the evaporator is a fourth liquid flow of
which the hydrogen chloride content is less than the hydrogen
chloride content in the liquid reaction medium of the first
reactor, and the first distillation column is supplied with this
fourth liquid flow; drawn off from the second reactor is a fifth
liquid flow which supplies the first reactor; and drawn off from
the first distillation column is a third gas flow which mostly
contains dichloropropanol and a sixth liquid flow which mostly
contains reaction intermediates such as monochloropropanediol, the
catalyst and reaction by-products such as partially chlorinated
glycerol oligomers, and drawn off from the sixth liquid flow is a
seventh liquid flow which constitutes a purge.
3. The process according to claim 2, comprising an additional
separation step in at least a second distillation column which is
supplied with a fourth gas flow drawn off from the second reactor,
and drawn off from which is a fifth gas flow which mostly contains
water and dichloropropanol and an eighth liquid flow which supplies
the second reactor.
4. The process according to claim 2, comprising two additional
separation steps, including one step in a second evaporator and
including another step in a second distillation column, which
second evaporator is supplied with the fifth liquid flow and from
which a sixth gas flow is drawn off and a ninth liquid flow which
supplies the first reactor, which second distillation column is
supplied with the sixth gas flow and from which an eighth liquid
flow is drawn off which supplies the reactor.
5. The process according to claim 4, wherein the second
distillation column is supplied with a fourth gas flow drawn off
from the second reactor.
6. The process according to claim 2, wherein drawn off from the
sixth liquid flow is a tenth liquid flow which supplies the second
reactor.
7. The process according to claim 2, wherein drawn off from the
sixth liquid flow is an eleventh liquid flow which supplies the
first reactor.
8. The process according to claim 2, wherein drawn off from the
second distillation column is a twelfth liquid flow which supplies
the first reactor.
9. The process according to claim 1, wherein the reaction is
carried out in the presence of a catalyst.
10. The process according to claim 9, wherein the reaction is
carried out in the presence of adipic acid as the catalyst.
11. A process for producing epichlorohydrin, the method comprising
(a) in a liquid reaction medium containing water, which is in
contact with a gaseous phase, glycerol is reacted with hydrogen
chloride under a partial pressure of hydrogen chloride in the
gaseous phase greater than 0.2 bar absolute to produce
dichloropropanol; (b) at least part of the liquid reaction medium
and optionally part of the gaseous phase from step a) is (are)
subjected to at least one separation operation and, prior to said
separation operation, the part of the liquid reaction medium and
the part of the gaseous phase from step a) are subjected to: i. at
least one treatment for reducing the weight ratio between the
hydrogen chloride and the water in the part of the liquid reaction
medium so as to attain a ratio less than or equal to the weight
ratio between the hydrogen chloride and the water in the binary
azeotropic hydrogen chloride/water composition at total pressure of
the separation operation; and/or ii. at least one treatment for
reducing the weight ratio between the water and the
dichloropropanol in the part of the liquid reaction medium so as to
attain a ratio less than or equal to the weight ratio between the
water and the dichloropropanol in the ternary
water/dichloropropanol/hydrogen chloride azeotrope at total
pressure of the separation operation; and (c) reacting the
dichloropropanol obtained to produce epichlorohydrin.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present patent application is a divisional of U.S.
application Ser. No. 12/529,778, filed Sep. 3, 2009, now allowed;
which is is a U.S. national stage application under 35 U.S.C.
.sctn.371 of International Application No. PCT/EP2008/052972 filed
Mar. 13, 2008, which claims the benefit of the French patent
application No. FR 0753837 filed on Mar. 14, 2007, and of the
provisional U.S. patent application Ser. No. 61/013707 filed on
Dec. 14, 2007, the content of each of these applications being
incorporated herein by reference for all purposes.
[0002] The present invention relates to a process for manufacturing
dichloropropanol. The present invention relates more specifically
to a process for manufacturing dichloropropanol via reaction
between glycerol and pressurized hydrogen chloride.
[0003] Dichloropropanol is a reaction intermediate in the
manufacture of epichlorohydrin and epoxy resins (Kirk-Othmer
Encyclopedia of Chemical Technology, Fourth Edition, 1992, Vol. 2,
page 156, John Wiley & Sons, Inc.).
[0004] According to known processes, dichloropropanol can be
obtained in particular by hypochlorination of allyl chloride, by
chlorination of allyl alcohol and by chlorodehydroxylation of
glycerol. The latter process exhibits the advantage that the
dichloropropanol can be obtained starting from fossil raw materials
or renewable raw materials and it is known that petrochemical
natural resources, from which the fossil materials originate, for
example oil, natural gas or coal, available on Earth are
limited.
[0005] International Application WO 2006/020234 describes a process
for manufacturing dichloropropanol via reaction between glycerol
and gaseous hydrogen chloride under a superatmospheric partial
pressure. Under such conditions, it is expected that it be
difficult to separate the reaction products such as water and
dichloropropanol, raw materials that have not reacted, including
hydrogen chloride, and reaction intermediates, and that it be
especially difficult to obtain dichloropropanol free from hydrogen
chloride, with, as a consequence, a significant loss of this raw
material.
[0006] The present invention aims to solve this problem by
providing a novel process which prevents the contamination of
dichloropropanol with hydrogen chloride and makes it possible to
separate the reaction products, water and dichloropropanol, and the
raw materials that have not reacted.
[0007] The invention hence relates to a process for manufacturing
dichloropropanol according to which: [0008] a) in a liquid reaction
medium containing water, in contact with a gaseous phase, glycerol
is reacted with hydrogen chloride under a partial pressure of
hydrogen chloride in the gaseous phase greater than 0.2 bar
absolute; and [0009] b) at least part of the liquid reaction medium
and optionally part of the gaseous phase from step a) is (are)
subjected to at least one separation operation and, prior to said
separation operation, the part of the liquid reaction medium and
the part of the gaseous phase from step a) are subjected to: [0010]
i. at least one treatment for reducing the weight ratio between the
hydrogen chloride and the water in the part of the liquid reaction
medium so as to attain a ratio less than or equal to the weight
ratio between the hydrogen chloride and the water in the binary
azeotropic hydrogen chloride/water composition at total pressure of
the separation operation; and/or [0011] ii. at least one treatment
for reducing the weight ratio between the water and the
dichloropropanol in the part of the liquid reaction medium so as to
attain a ratio less than or equal to the weight ratio between the
water and the dichloropropanol in the ternary
water/dichloropropanol/hydrogen chloride azeotrope at total
pressure of the separation operation.
[0012] A first main feature of the present invention lies in the
fact that at the end of the treatment from step bi) of the process,
the weight ratio between the hydrogen chloride and the water in the
liquid reaction medium is less than or equal to the weight ratio
between the hydrogen chloride and the water in the binary
azeotropic hydrogen chloride/water composition at total pressure of
the separation operation. This ratio is 0.25 at a pressure of 1 bar
absolute. The weight ratio between the hydrogen chloride and the
water in the liquid reaction medium at the end of the treatment i)
is preferably less than 0.95 times the weight ratio between the
hydrogen chloride and the water of the binary azeotropic
water/hydrogen chloride composition at total pressure of the
separation operation and more preferably less than or equal to 0.9
times the latter weight ratio.
[0013] The weight ratio between the hydrogen chloride and the water
in the binary azeotropic hydrogen chloride/water composition varies
with pressure as shown by the liquid/vapour equilibrium data for
the binary azeotropic hydrogen chloride/water composition given in
Table 1 below:
TABLE-US-00001 TABLE 1 Pressure HCl in azeotrope HCl/water in (bar
Temperature (g HCl/100 g azeotrope absolute) (.degree. C.)
azeotrope) (g/g) 0.067 48.74 23.42 0.305 0.333 85.21 21.88 0.280
0.493 90.24 21.37 0.272 0.720 99.65 20.92 0.265 1 110 20 0.25 2 129
18 0.22 3 142 16 0.19 5 159 14 0.16 10 185 11 0.12 30 236 5 0.05 50
265 3 0.05
[0014] The values of 0.067 to 0.720 bar are taken from Bonner and
Titus (J. Amer. Chem. Soc. 52, 633, (1930)). The values of 1 to 50
bar were calculated using the ASPEN+ calculation programme.
[0015] A second main feature of the present invention lies in the
fact that at the end of the treatment from step bii) of the
process, the weight ratio between the water and the
dichloropropanol in the liquid reaction medium is less than or
equal to the weight ratio between the water and the
dichloropropanol in the ternary water/dichloropropanol/hydrogen
chloride azeotrope at total pressure of the separation operation.
This ratio is 1.6 at a pressure of 1 bar absolute. The weight ratio
between the water and the dichloropropanol in the liquid reaction
medium at the end of the treatment from step bii) is preferably
less than 0.95 times the weight ratio between the water and the
dichloropropanol in the ternary water/dichloropropanol/hydrogen
chloride azeotrope at the product separation pressure, more
preferably less than or equal to 0.9 times and most particularly
preferably less than or equal to 0.8 times the latter weight
ratio.
[0016] It has been discovered that, under these conditions, it is
possible to recover dichloropropanol free from hydrogen chloride
with the following advantages: [0017] 1. the dichloropropanol may
be used in subsequent reactions such as the manufacture of
epichlorohydrin for example, while avoiding: [0018] a.
overconsumption of basic agent; and [0019] b. loss of recoverable
hydrogen chloride; [0020] 2. limitation of corrosion phenomena in
the processes of transfer and storage of dichloropropanol.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1 shows a ternary dichloropropanol/hydrogen
chloride/water diagram.
[0022] FIG. 2 shows first to fourth combinations of embodiments of
the process according to the present invention.
[0023] FIG. 3 shows a fifth combination of embodiments of the
process according to the present invention.
[0024] FIG. 4 shows a sixth combination of embodiments of the
process according to the present invention.
[0025] FIG. 5 shows seventh to thirteenth combinations of
embodiments of the process according to the present invention.
[0026] The expression "dichloropropanol free from hydrogen
chloride" is understood to mean dichloropropanol of which the
hydrogen chloride content is less than or equal to 5 g/kg of
dichloropropanol, preferably less than or equal to 0.5 g/kg, more
preferably less than or equal to 0.05 g/kg and most particularly
preferably less than or equal to 0.005 g/kg.
[0027] In the process according to the invention, the total
pressure of the reaction from step a) is generally at least 1 bar
absolute, preferably at least 3 bar absolute, more preferably at
least 5 bar absolute and most particularly preferably at least 10
bar absolute. It is at most 50 bar absolute and preferably at most
30 bar absolute.
[0028] In the process according to the invention, the partial
pressure of the hydrogen chloride from step a) is preferably at
least 0.4 bar absolute, more preferably at least 1 bar absolute,
more preferably still at least 2 bar absolute and most particularly
preferably at least 5 bar absolute. It is at most 50 bar absolute
and preferably at most 30 bar absolute.
[0029] In the process according to the invention, the total
pressure of the separation operation from step b) is generally less
than or equal to the total pressure of the reaction from step
a).
[0030] In the rest of the document, the expressions "pressure" and
"total pressure" will be used indifferently to denote the total
pressure.
[0031] In a first embodiment of the process according to the
invention, the treatment from step bi) comprises an operation
chosen from the operations of evaporation, distillation and
stripping of the part of the liquid reaction medium from step a),
and combinations of at least two of them.
[0032] In a first variant of the first embodiment, the treatment
comprises an evaporation operation. The term "evaporation" is
understood to mean the separation of a substance by heating,
optionally under a reduced pressure. The temperature of the part of
the liquid reaction medium from step a) during the evaporation
operation is generally at least 70.degree. C., usually at least
90.degree. C., frequently at least 110.degree. C. and more
specifically at least 120.degree. C. This temperature is generally
at most 160.degree. C., usually at most 150.degree. C., frequently
at most 140.degree. C. and more specifically at most 130.degree. C.
This temperature is preferably above the reaction temperature of
step a) if the pressure of the evaporation operation is higher than
to the reaction pressure of step a). This temperature is preferably
lower than or equal to the reaction temperature of step a) if the
pressure of the evaporation operation is lower than or equal to the
reaction pressure of step a). The evaporation operation may be
carried out using any equipment such as, for example, a still, a
natural circulation, rising film, falling film or rising and
falling film or forced circulation tubular evaporator, or a plate
evaporator. In this first variant, the evaporation may be carried
out under a pressure of 1 bar absolute, under a pressure above 1
bar absolute or under a pressure below 1 bar absolute. It is
preferred to carry out the evaporation under a pressure of at most
1.1 bar absolute. A simple means of carrying out the evaporation
operation consists in bringing the part of the liquid reaction
medium from step a) to atmospheric pressure by simple venting of
this part to the atmosphere. In this first variant, the evaporation
operation may be carried out in the presence or absence of a gas
flow. It is preferred to carry out the evaporation under a gas
flow.
[0033] In a second variant of the first embodiment, the treatment
comprises a distillation operation. The term "distillation" is
understood to mean the direct transition from the liquid state to
the gas state, then condensation of the vapours obtained. The term
"fractional distillation" is understood to mean a series of
distillations carried out on the successively condensed vapours.
The fractional distillation treatment is preferred. In this second
variant, the temperature of the part of the liquid reaction medium
from step a) is generally at least 70.degree. C., usually at least
90.degree. C., frequently at least 110.degree. C. and more
specifically at least 120.degree. C. This temperature is generally
at most 160.degree. C., usually at most 150.degree. C., frequently
at most 140.degree. C. and more specifically at most 130.degree. C.
This temperature is preferably higher than or equal to the reaction
temperature of step a) if the pressure of the distillation
operation is higher than or equal to the reaction pressure of step
a). This temperature is preferably below the temperature of step a)
if the pressure of the distillation operation is lower than the
reaction pressure of step a). In this second variant, the
distillation may be carried out under a pressure of 1 bar absolute,
under a pressure above 1 bar absolute or under a pressure below 1
bar absolute. It is preferred to carry out the distillation under a
pressure of at most 1.5 bar absolute. The distillation operation
may be carried out using any equipment such as, for example, a
conventional plate column or a "dual-flow" type plate column, or
else a column with random or structured packing. In this second
variant, the distillation operation may be carried out in the
presence or absence of a gas flow. It is preferred to carry out the
distillation without a gas flow.
[0034] In a third variant of the first embodiment, the treatment
comprises a stripping operation. The term "stripping" is understood
to mean the separation of a substance by entrainment using the
vapour of a material that does not dissolve this substance. In the
process according to the invention, this material can be any
compound which is inert with respect to dichloropropanol such as,
for example, steam, air, nitrogen and carbon dioxide. It is
preferred to use nitrogen, preferably relatively dry nitrogen, that
is to say having a water content of at most 1000 ppm by weight. In
this third variant, the temperature of the part of the liquid
reaction medium from step a) is generally at least 70.degree. C.,
usually at least 90.degree. C., frequently at least 110.degree. C.
and more specifically at least 120.degree. C. This temperature is
generally at most 160.degree. C., usually at most 150.degree. C.,
frequently at most 140.degree. C. and more specifically at most
130.degree. C. This temperature is preferably higher than or equal
to the reaction temperature of step a) if the pressure of the
stripping operation is higher than or equal to the reaction
pressure of step a). This temperature is preferably below the
temperature of step a) if the pressure of the stripping operation
is lower than the reaction pressure of step a). In this third
variant, the stripping may be carried out under a pressure of 1 bar
absolute, under a pressure above 1 bar absolute or under a pressure
below 1 bar absolute. It is preferred to carry out the stripping
under a pressure of at most 1.1 bar absolute.
[0035] In a fourth variant of the first embodiment according to the
invention, the stripping and distillation treatments are combined,
for example in a stripping column surmounted by a distillation
section.
[0036] In the first embodiment of the process according to the
invention, at the end of the treatment from step bi), a first
fraction comprising at least 80 wt % of hydrogen chloride and a
second fraction comprising dichloropropanol are recovered, the
latter containing at most 30 wt % of hydrogen chloride, preferably
at most 20 wt % of hydrogen chloride and particularly preferably at
most 10 wt % of hydrogen chloride.
[0037] The hydrogen chloride from the first fraction preferably
contains at most 10 wt % of water and most particularly preferably
at most 5 wt %. The hydrogen chloride may be recycled to step a) of
the process according to the invention or be used in any other
process.
[0038] In a second embodiment of the process according to the
invention, the treatment from step bi) comprises an operation
chosen from the operations of addition of glycerol and/or glycerol
esters, and/or of monochloropropanediol and/or
monochloropropanediol esters and/or of a basic agent to the part of
the liquid reaction medium from step a).
[0039] In a first variant of the second embodiment of the process
according to the invention, the treatment from step bi) comprises
the operation of addition of glycerol to the part of the liquid
reaction medium from step a).
[0040] The glycerol in the process according to the invention may
be obtained starting from fossil raw materials or starting from
renewable raw materials, preferably starting from renewable raw
materials.
[0041] The expression "fossil raw materials" is understood to mean
materials derived from the treatment of petrochemical natural
resources, for example oil, natural gas and coal. Among these
materials, organic compounds that consist of a number of carbon
atoms which is a multiple of 3 are preferred. Allyl chloride, allyl
alcohol and "synthetic" glycerol are particularly preferred. The
term "synthetic" glycerol is understood to mean a glycerol
generally obtained from petrochemical resources.
[0042] The expression "renewable raw materials" is understood to
mean materials derived from the treatment of renewable natural
resources. Among these materials, "natural" glycerol is preferred.
"Natural" glycerol may, for example, be obtained by conversion of
sugars via thermochemical processes. These sugars may possibly be
obtained starting from biomass, as described in "Industrial
Bioproducts: Today and Tomorrow, Energetics, Incorporated for the
U.S. Department of Energy, Office of Energy Efficiency and
Renewable Energy, Office of the Biomass Program, July 2003, pages
49, 52 to 56". One of these processes is, for example, catalytic
hydrogenolysis of sorbitol obtained by thermochemical conversion of
glucose. Another process is, for example, catalytic hydrogenolysis
of xylitol obtained by hydrogenation of xylose. Xylose may, for
example, be obtained by hydrolysis of hemicellulose contained in
maize fibres. The expressions "natural glycerol" or "glycerol
obtained from renewable raw materials" are understood to mean, in
particular, glycerol obtained during the manufacture of biodiesel
or else glycerol obtained during conversions of fats or oils of
vegetable or animal origin in general such as saponification,
transesterification or hydrolysis reactions.
[0043] Among the oils that can be used to manufacture natural
glycerol, mention may be made of all common oils, such as palm,
palm kernel, coconut, babassu, old or new rapeseed, sunflower,
maize, castor and cottonseed oils, arachis, soybean, linseed and
sea kale oils, all the oils derived from, for example, sunflower or
rapeseed plants obtained by genetic modification or
hybridization.
[0044] Use can even be made of used frying oils, various animal
oils, such as fish oils, tallow, lard and even abattoir fats.
[0045] Among the oils used, mention may also be made of oils
partially modified, for example, by polymerization or
oligomerization such as, for example, the "stand oils" of linseed
and sunflower oils and blown vegetable oils.
[0046] A particularly suitable glycerol may be obtained during the
conversion of animal fats. Another particularly suitable glycerol
may be obtained during the manufacture of biodiesel. Another
particularly suitable glycerol may be obtained during the fatty
acid manufacture.
[0047] In a first aspect of the first variant of the second
embodiment of the process according to the invention, a glycerol
external to the process according to the invention is used. The
term "external" glycerol is understood to mean glycerol which is
not recycled in the process according to the invention.
[0048] In a second aspect of the first variant of the second
embodiment of the process according to the invention, a mixture of
glycerol "external" to the process according to the invention and
of glycerol "internal" to the process according to the invention is
used. The term "internal" glycerol is understood to mean glycerol
which has been separated from the reaction products formed in the
process according to the invention and which has then been recycled
in the process according to the invention.
[0049] In a second variant of the second embodiment, the treatment
from step bi) comprises the operation of addition of glycerol
esters to the part of the liquid reaction medium from step a).
[0050] The glycerol ester used in the process according to the
invention may be obtained by any route, for example by reaction
between glycerol and an organic acid. The organic acids preferred
in the process according to the invention are the carboxylic acids
used as chlorodehydroxylation catalysts for glycerol such as those
described in the Patent Application in the name of Solvay SA (WO
2005/054167) and in Application WO 2006/020234.
[0051] In a first aspect of the second variant of the second
embodiment of the process according to the invention, a glycerol
ester external to the process according to the invention is used.
The term "external" glycerol ester is understood to mean a glycerol
ester which is not recycled in the process according to the
invention.
[0052] In a second aspect of the second variant of the second
embodiment of the process according to the invention, a glycerol
ester "internal" to the process according to the invention is used.
The term "internal" glycerol ester is understood to mean a glycerol
ester which has been separated from the reaction products formed in
the process according to the invention and which has then been
recycled in the process according to the invention.
[0053] In a third aspect of the second variant of the second
embodiment of the process according to the invention, a mixture of
glycerol ester "external" to the process according to the invention
and of glycerol ester "internal" to the process according to the
invention is used.
[0054] In a third variant of the second embodiment of the process
according to the invention, the treatment from step bi) comprises
the operation of addition of monochloropropanediol to the part of
the liquid reaction medium from step a).
[0055] The monochloropropanediol used in the process according to
the invention may be obtained by any route, for example by reaction
between glycerol and the chlorinating agent or by hydrolysis of
epichlorohydrin.
[0056] In a first aspect of the third variant of the second
embodiment of the process according to the invention, a
monochloropropanediol external to the process according to the
invention is used. The term "external" monochloropropanediol is
understood to mean monochloropropanediol which is not one of the
products formed in the process according to the invention.
[0057] In a second aspect of the third variant of the second
embodiment of the process according to the invention, which is
preferred, a monochloropropanediol internal to the process
according to the invention is used. The term "internal"
monochloropropanediol is understood to mean monochloropropanediol
which is one of the products formed in the process according to the
invention, which has been separated from the other reaction
products and which has then been recycled in the process according
to the invention.
[0058] In a fourth variant of the second embodiment of the process
according to the invention, the treatment from step bi) comprises
the operation of addition of monochloropropanediol ester to the
part of the liquid reaction medium from step a).
[0059] The monochloropropanediol ester used in the process
according to the invention may be obtained by any route, for
example by reaction between the monochloropropanediol and an
organic acid. The organic acids preferred in the process according
to the invention are the carboxylic acids used as
chlorodehydroxylation catalyst for glycerol such as those described
in the Patent Application in the name of Solvay SA (WO 2005/054167)
and in Application WO 2006/020234.
[0060] In a first aspect of the fourth variant of the second
embodiment of the process according to the invention, a
monochloropropanediol ester external to the process according to
the invention is used. The term "external" monochloropropanediol
ester is understood to mean a monochloropropanediol ester which is
not one of the products formed in the process according to the
invention.
[0061] In a second aspect of the fourth variant of the second
embodiment of the process according to the invention, which is
preferred, a monochloropropanediol ester internal to the process
according to the invention is used. The term "internal"
monochloropropanediol ester is understood to mean a
monochloropropanediol ester which is one of the products formed in
the process according to the invention, which has been separated
from the other reaction products and which has then been recycled
in the process according to the invention.
[0062] The glycerol, glycerol esters, monochloropropanediol and
monochloropropanediol esters may be added as a mixture of two,
three or four of these compounds.
[0063] In the aspects of the various variants of the second
embodiment, which involve internal glycerol, internal glycerol
esters, internal monochloropropanediol and internal
monochloropropanediol esters, these compounds may be accompanied by
other compounds, for instance impurities of the process, such as
for example glycerol oligomers that are chlorinated and/or
esterified to a greater or lesser extent.
[0064] Without wishing to be tied to one theoretical explanation,
it is believed that in the various variants of the second
embodiment of the process according to the invention, the glycerol
and/or glycerol esters and/or monochloropropanediol and/or
monochloropropanediol esters react with the hydrogen chloride
present in the liquid reaction medium from step a) so as to
generate at least dichloropropanol and/or dichloropropanol esters
and/or monochloropropanediol and/or monochloropropanediol esters
and water, with the following additional advantages: increase of
the dichloropropanol yield, formation of a reaction intermediate
that can be recycled after separation in step a) of the process
according to the invention, and decrease of the hydrogen
chloride/water ratio.
[0065] In these first, second, third and fourth variants of the
second embodiment of the process according to the invention, the
molar ratio of the amount of glycerol and/or glycerol esters and/or
monochloropropanediol and/or monochloropropanediol esters to the
amount of hydrogen chloride in the part of the reaction medium from
step a) after addition of the glycerol and/or glycerol esters
and/or monochloropropanediol and/or monochloropropanediol esters
and before the optional reaction with the hydrogen chloride is
generally at least 1 mol/mol, preferably at least 3 mol/mol and
more particularly preferably at least 5 mol/mol.
[0066] In these first, second, third and fourth variants of the
second embodiment of the process according to the invention, the
treatment temperature is generally at least 60.degree. C., usually
at least 80.degree. C., frequently at least 100.degree. C. and more
specifically at least 110.degree. C. This temperature is generally
at most 150.degree. C., usually at most 140.degree. C., frequently
at most 130.degree. C. and more specifically at most 120.degree. C.
This temperature is preferably higher than or equal to the reaction
temperature of step a) if the pressure of the treatment is higher
than or equal to the reaction pressure of step a). This temperature
is preferably below the temperature of step a) if the pressure of
the treatment is lower than the reaction pressure of step a). In
these variants, the pressure may be 1 bar absolute, above 1 bar
absolute or below 1 bar absolute. It is preferred to operate under
a pressure of at most 1.2 bar absolute. In these variants, the
treatment time is generally at least 15 min, preferably at least 30
min and particularly preferably at least 45 min. This time is at
most 8 h, preferably at most 4 h and particularly preferably at
most 2 h. The treatment may be carried out in batch mode in a mixed
reactor or continuously in a plug-flow reactor or in a mixed
reactor.
[0067] In a fifth variant of the second embodiment of the process
according to the invention, the treatment from step bi) comprises
the operation of addition of a basic compound to the part of the
liquid reaction medium from step a).
[0068] In this fifth variant of the second embodiment of the
process according to the invention, the basic compound may be an
organic or inorganic basic compound. Organic basic compounds are
for example amines, phosphines or arsines, preferably sterically
hindered, and ammonium, phosphonium or arsonium hydroxides.
Inorganic basic compounds are preferred. The expression "inorganic
compounds" is understood to mean compounds which do not contain a
carbon-hydrogen bond. The inorganic basic compound may be chosen
from alkali and alkaline-earth metal oxides, hydroxides,
carbonates, hydrogencarbonates, phosphates, hydrogenphosphates and
borates, and mixtures thereof. Alkali and alkaline-earth metal
oxides and hydroxides are preferred.
[0069] In this variant, the basic compound may be in the form of a
liquid, an essentially anhydrous solid, a hydrated solid, an
aqueous and/or organic solution or an aqueous and/or organic
suspension. The basic compound is preferably in the form of an
essentially anhydrous solid, a hydrated solid, an aqueous solution
or an aqueous suspension.
[0070] The expression "essentially anhydrous solid" is understood
to mean a solid of which the water content is less than 20 g/kg,
preferably less than or equal to 10 g/kg and more preferably less
than or equal to 1 g/kg.
[0071] The expression "hydrated solid" is understood to mean a
solid of which the water content is at least 20 g/kg and at most
700 g/kg, preferably at least 50 g/kg and at most 650 g/kg and most
particularly preferably at least 130 g/kg and at most 630 g/kg. The
hydrates which denote solid combinations of substances with one or
more water molecules are examples of hydrated solids.
[0072] When the basic compound is used in the form of an aqueous
solution, its content in the aqueous solution is generally greater
than 20 g/kg, preferably greater than or equal to 70 g/kg and more
preferably greater than or equal to 150 g/kg. This content is
generally less than or equal to the solubility of the basic solid
in water at the temperature of the treatment from step bi).
[0073] When the basic compound is used in the form of an aqueous
suspension, its content in the aqueous suspension is generally
greater than the solubility of the basic solid in water at the
temperature of the treatment from step bi), preferably greater than
or equal to 20 g/kg and more preferably greater than or equal to 70
g/kg.
[0074] The preferred basic compounds are in the form of
concentrated aqueous solutions or suspensions of sodium hydroxide
or calcium hydroxide or in the form of purified caustic brine. The
expression "purified caustic brine" here means sodium hydroxide
which contains sodium chloride such as, for example, that produced
in a diaphragm electrolysis process. The sodium hydroxide content
of the purified caustic brine is generally greater than or equal to
30 g/kg, preferably greater than or equal to 40 g/kg and more
preferably greater than or equal to 60 g/kg. This sodium hydroxide
content is generally less than or equal to 300 g/kg, preferably
less than or equal to 250 g/kg and more preferably less than or
equal to 200 g/kg. The sodium chloride content of the purified
caustic brine is generally greater than or equal to 30 g/kg,
preferably greater than or equal to 50 g/kg and more preferably
greater than or equal to 70 g/kg. This sodium chloride content is
generally less than or equal to 250 g/kg, preferably less than or
equal to 200 g/kg and more preferably less than or equal to 180
g/kg.
[0075] Without wishing to be tied to one theoretical explanation,
it is believed that in this fifth variant of the second embodiment
of the process according to the invention, the basic compound
reacts with the hydrogen chloride present in the liquid reaction
medium from step a) so as to generate at least one salt and water,
the water formed contributing to the reduction of the hydrogen
chloride/water ratio. The salt generated in this variant may also
have a salting-out effect with respect to the hydrogen chloride,
that is to say contribute to reducing the solubility of hydrogen
chloride in the liquid reaction medium.
[0076] In this fifth variant of the second embodiment of the
process according to the invention, the molar ratio of the basic
compound to the hydrogen chloride in the part of the reaction
medium from step a) after addition of the basic compound and before
the optional reaction with the hydrogen chloride is generally at
least 0.4, preferably at least 0.6 and more particularly preferably
at least 0.8.
[0077] In this fifth variant of the second embodiment of the
process according to the invention, the treatment temperature is
generally at least 60.degree. C., usually at least 80.degree. C.,
frequently at least 100.degree. C. and more specifically at least
110.degree. C. This temperature is generally at most 150.degree.
C., usually at most 140.degree. C., frequently at most 130.degree.
C. and more specifically at most 120.degree. C. This temperature is
preferably higher than or equal to the reaction temperature of step
a) if the pressure of the treatment is higher than or equal to the
reaction pressure of step a). This temperature is preferably below
the temperature of step a) if the pressure of the treatment is
lower than the reaction pressure of step a). In this variant, the
treatment pressure may be 1 bar absolute, above 1 bar absolute or
below 1 bar absolute. It is preferred to operate under a pressure
of at most 1.1 bar absolute. In this variant, the treatment time is
generally at least 0.5 min, preferably at least 1 min and
particularly preferably at least 2 min. This time is at most 60
min, preferably at most 30 min and particularly preferably at most
10 min. The operation may be carried out in batch mode or
continuously in a plug-flow reactor or in a mixed reactor.
[0078] In a third embodiment of the process according to the
invention, the treatment from step bi) comprises an operation
chosen from the operations of addition of: [0079] (A) water; or
[0080] (B) a dichloropropanol/water/hydrogen chloride mixture in
which: [0081] 1) the hydrogen chloride/water weight ratio is less
than the weight ratio between the hydrogen chloride and the water
in the binary azeotropic hydrogen chloride/water composition at
total pressure of the separation operation; and/or [0082] 2) the
dichloropropanol/water weight ratio is less than the weight ratio
between the water and the dichloropropanol in the ternary
water/dichloropropanol/hydrogen chloride azeotrope at total
pressure of the separation operation; [0083] or [0084] (C) a
compound that forms an azeotrope with hydrogen chloride and water,
and of which the boiling point is below the boiling point of the
ternary water/dichloropropanol/hydrogen chloride azeotrope at total
pressure of the separation operation; or [0085] (D) a salt-out
salt,
[0086] to the part of the liquid reaction medium from step a).
[0087] The boiling point of the ternary
water/dichloropropanol/hydrogen chloride azeotrope is 106.degree.
C. under a pressure of 1 bar absolute and this boiling point varies
with the pressure.
[0088] In a first variant of the third embodiment of the process
according to the invention, the treatment from step bi) comprises
the addition of water to the part of the liquid reaction medium
from step a).
[0089] In a first aspect of the first variant of the third
embodiment of the process according to the invention, water
external to the process according to the invention is used. The
term "external" water is understood to mean water which is not
recycled in the process according to the invention.
[0090] In a second aspect of the first variant of the third
embodiment of the process according to the invention, water
"internal" to the process according to the invention is used. The
term "internal" water is understood to mean water which has been
separated from the reaction products formed in the process
according to the invention and which has then been recycled in the
process according to the invention.
[0091] In a third aspect of the first variant of the third
embodiment of the process according to the invention, a mixture of
water "external" to the process according to the invention and of
water "internal" to the process according to the invention is
used.
[0092] In a second variant of the third embodiment of the process
according to the invention, the treatment from step bi) comprises
the addition of a dichloropropanol/water/hydrogen chloride mixture
in which the hydrogen chloride/water weight ratio is less than the
weight ratio between the hydrogen chloride and the water in the
binary azeotropic hydrogen chloride/water composition at total
pressure of the separation operation. This ratio is preferably less
than 0.25. This ratio is more preferably less than or equal to
0.15, even more preferably less than or equal to 0.1 and most
particularly preferably less than or equal to 0.005.
[0093] In a first aspect of the second variant of the third
embodiment of the process according to the invention, the
dichloropropanol/water weight ratio in the
dichloropropanol/water/hydrogen chloride mixture is greater than or
equal to the weight ratio between the dichloropropanol and the
water in the binary azeotropic dichloropropanol/water composition
at total pressure of the separation operation. This ratio is
preferably greater than or equal to 0.30. The weight ratio between
the dichloropropanol and the water in the binary azeotropic
dichloropropanol/water composition at a pressure of 1 bar absolute
is 0.3.
[0094] In a second aspect of the second variant of the third
embodiment of the process according to the invention, which is
preferred, the dichloropropanol/water weight ratio in the
dichloropropanol/water/hydrogen chloride mixture is less than the
weight ratio between the dichloropropanol and the water in the
binary azeotropic dichloropropanol/water composition at total
pressure of the separation operation. This ratio is preferably at
most 0.30, preferably at most 0.2, more preferably at most 0.1 and
most particularly preferably at most 0.05.
[0095] In a third variant of the third embodiment of the process
according to the invention, the treatment from step bi) comprises
the addition of a compound that forms an azeotrope with hydrogen
chloride and water, and of which the boiling point is below the
boiling point of the ternary water/dichloropropanol/hydrogen
chloride azeotrope at total pressure of the separation operation,
which boiling point is 106.degree. C. under a pressure of 1 bar
absolute. This boiling point is preferably less than 104.degree.
C., more preferably less than or equal to 100.degree. C. and most
particularly preferably less than or equal to 98.degree. C. Without
being limiting, examples of such compounds which may be used
include chlorobenzene, toluene, benzene, heptane and octane.
[0096] In a fourth variant of the third embodiment of the process
according to the invention, the treatment from step bi) comprises
the addition of a salt-out salt to the part of the liquid reaction
medium from step a). The expression "salt-out salt" is understood
to mean a salt which contributes to reducing the solubility of
hydrogen chloride in the liquid reaction medium.
[0097] In a first aspect of the fourth variant of the third
embodiment of the process according to the invention, a salt
external to the process according to the invention is used. The
term "external" salt is understood to mean a salt which is not
recycled in the process according to the invention.
[0098] In a second aspect of the fourth variant of the third
embodiment of the process according to the invention, a salt
"internal" to the process according to the invention is used. The
term "internal" salt is understood to mean a salt which has been
separated from the reaction products formed in the process
according to the invention and which has then been recycled in the
process according to the invention. These salts may, for example,
be present in the reactants, such as glycerol.
[0099] In a third aspect of the fourth variant of the third
embodiment of the process according to the invention, a mixture of
a salt "external" to the process according to the invention and of
a salt "internal" to the process according to the invention is
used.
[0100] The salt is preferably chosen from alkali and alkaline-earth
metal halides, sulphates, hydrogensulphates, phosphates,
hydrogenphosphates and borates, and mixtures thereof. Alkali metal
halides and sulphates are preferred, sodium and potassium chlorides
and sulphates being more preferred, sodium chloride being most
particularly preferred.
[0101] Without wishing to be tied to any one theoretical
explanation, it is believed that the addition of salt reduces the
solubility of hydrogen chloride in the part of the liquid reaction
medium from step a).
[0102] In a fourth embodiment of the process according to the
invention, the treatment from step bi) comprises an operation
chosen from the operations of adsorption and/or liquid/liquid
extraction, the adsorption operation being preferred.
[0103] The adsorbents may be chosen from molecular sieves,
preferably from molecular sieves having a pore size of at least 0.3
nm and at most 1 nm. Examples of such molecular sieves are type A
or X molecular sieves. The molecular sieves are preferably
acid-resistant.
[0104] Without wishing to be tied to any one theoretical
explanation, it is believed that such compounds make it possible to
adsorb hydrogen chloride from the part of the liquid reaction
medium from step a).
[0105] At the end of the treatment from step bi), the adsorbent may
be subjected to operations intended to separate the hydrogen
chloride from the adsorbent, such as the operations of stripping or
regeneration by heating. The thus separated hydrogen chloride may
be recycled to step a) of the reaction and the thus separated
adsorbent may be recycled to the treatment from step bi) of the
process according to the invention.
[0106] In the four embodiments of the process according to the
invention described above, the part of the reaction medium at the
end of the treatment from step bi) may be subjected to at least one
operation of separation by distillation, recovered at the end of
which is a first portion (I) comprising dichloropropanol and water,
said portion containing at most 20 g of hydrogen chloride/kg of
portion; and [0107] a second portion (IIa) comprising hydrogen
chloride, water and dichloropropanol, and a third portion (IIIa)
containing dichloropropanol; or [0108] a second portion (IIb)
comprising hydrogen chloride, water and dichloropropanol, and a
third portion (IIIb) comprising hydrogen chloride and water; or
[0109] a second portion (IIc) comprising hydrogen chloride and
water, and a third portion (IIIc) containing water.
[0110] The first portion (I) preferably contains at most 15 g of
hydrogen chloride/kg of mixture, preferably at most 10 g/kg and
particularly preferably at most 1 g/kg. This mixture contains at
least 1 ppm by weight of hydrogen chloride per kg of mixture. The
first portion (I) contains from 10 to 26 wt %, preferably 23 wt %,
of dichloropropanol, and from 74 to 90 wt %, preferably 77 wt %, of
water, the weight percentages being relative to the sum of the
weights of water and dichloropropanol in the first portion.
[0111] The second portion comprising hydrogen chloride, water and
dichloropropanol (IIa, IIb) contains from 43 to 63 wt %, preferably
53 wt %, of water, from 23 to 43 wt %, preferably 33 wt %, of
dichloropropanol and from 4 to 24 wt %, preferably 14 wt %, of
hydrogen chloride, the weight percentages being relative to the sum
of the weights of hydrogen chloride, water and dichloropropanol in
the second portion.
[0112] The third portion (IIIa) containing dichloropropanol
comprises at least 900 g of dichloropropanol per kg of said third
portion, preferably at least 950 g/kg and more preferably at least
990 g/kg.
[0113] The second portion (IIc) and the third portion (IIIb),
containing hydrogen chloride and water, contain from 18 to 22 wt %,
preferably 20 wt %, of hydrogen chloride, and from 78 to 82 wt %,
preferably 80 wt %, of water, the weight percentages being relative
to the sum of the weights of water and hydrogen chloride in said
second (IIc) and third (IIIb) portions.
[0114] The third portion (IIIc) containing water comprises at least
950 g of water per kg of said third portion (IIIc), preferably at
least 990 g/kg and more preferably at least 995 g/kg.
[0115] These situations may be visualized in the ternary
dichloropropanol/hydrogen chloride/water diagram from FIG. 1 where
the peaks represent pure compounds, point D represents a ternary
azeotropic dichloropropanol/hydrogen chloride/water composition,
point E represents a binary azeotropic hydrogen chloride/water
composition, point F represents a binary azeotropic
dichloropropanol/water composition and point G is the intersection
point between the dichloropropanol-water axis and a straight line
comprising points A and D . For these particular compositions D, E,
and F, the following will respectively be denoted: by (d), the
weight ratio between dichloropropanol and water in composition D,
by (e), the weight ratio between hydrogen chloride and water in
composition E, by (f), the weight ratio between water and
dichloropropanol in composition F.
[0116] Separation into the portions I, IIa and IIIa is obtained
when the part of the reaction medium at the end of the treatment
from step bi) has a dichloropropanol/hydrogen chloride/water
composition which lies in the BDF zone of the diagram from FIG.
1.
[0117] Separation into the portions I, IIb and IIIb is obtained
when the part of the reaction medium at the end of the treatment
from step bi) has a dichloropropanol/hydrogen chloride/water
composition which lies in the DEF zone of the diagram from FIG.
1.
[0118] Separation into the portions I, IIc and IIIc is obtained
when the part of the reaction medium at the end of the treatment
from step bi) has a dichloropropanol/hydrogen chloride/water
composition which lies in the EFC zone of the diagram from FIG.
1.
[0119] In a fifth embodiment of the process according to the
invention, the treatment from step bii) comprises an operation
chosen from the operations of adsorption and/or liquid/liquid
extraction.
[0120] The adsorption operation may be carried out using an
adsorbent chosen from molecular sieves, preferably from molecular
sieves having a pore size of at least 0.3 nm and at most 1 nm.
Examples of such molecular sieves are type A or X molecular sieves.
The molecular sieves are preferably acid-resistant.
[0121] The liquid/liquid extraction operation may be carried out
using a semi-permeable membrane.
[0122] Without wishing to be tied to any one theoretical
explanation, it is believed that such compounds make it possible to
adsorb or to extract water or a mixture comprising water and
hydrogen chloride from the part of the liquid reaction medium from
step a).
[0123] At the end of the treatment from step bii), the adsorbent
and the extraction liquid may be subjected to operations intended
to separate the water and hydrogen chloride from the adsorbent or
from the extraction liquid, such as the operations of evaporation,
stripping or regeneration by heating. The thus separated hydrogen
chloride may be recycled to step a) of the reaction and the thus
separated adsorbent and extraction liquid may be recycled to step
bii) of the process according to the invention.
[0124] In the fifth embodiment of the process according to the
invention described above, the part of the reaction medium at the
end of the treatment from step bii) may be subjected to at least
one separation by distillation, recovered during which is at least
a first part comprising dichloropropanol and a second part
comprising hydrogen chloride.
[0125] This situation may be visualized in the ternary diagram of
the dichloropropanol/hydrogen chloride/water composition from FIG.
1.
[0126] Separation into the parts respectively comprising
dichloropropanol and hydrogen chloride is obtained when the part of
the reaction medium at the end of the treatment from step bii) has
a dichloropropanol/hydrogen chloride/water composition which lies
in the ABD zone of the diagram from FIG. 1.
[0127] The first part containing dichloropropanol comprises at
least 900 g of dichloropropanol per kg of said first part,
preferably at least 950 g/kg and more preferably at least 990
g/kg.
[0128] The second part containing hydrogen chloride comprises at
least 900 g of hydrogen chloride per kg of said second part,
preferably at least 950 g/kg and more preferably at least 990 g/kg.
This hydrogen chloride may be recycled to step a) of the process
according to the invention.
[0129] The various embodiments described above may be combined
together in any manner. Some of these combinations are described
herein below.
[0130] In a first combination of embodiments of the process
according to the invention which is presented in FIG. 2, a first
reactor (1) is continuously supplied with glycerol, gaseous
hydrogen chloride and a catalyst respectively via the lines (2),
(3) and (4). The reactor is permanently kept under a partial
pressure of hydrogen chloride above 0.2 bar absolute. A liquid flow
in which the weight ratio between the hydrogen chloride and the
water is above (e) and the ratio between the dichloropropanol and
the water is higher than (d) (ABD zone of the ternary diagram from
FIG. 1) is continuously drawn off from the reactor (1) via the line
(5) and supplies a stripping machine (6) in which the pressure is
kept at less than 1 bar absolute and in which a flow of inert gas
is introduced via the line (7). A gas flow containing hydrogen
chloride is drawn off from the stripping machine (6) via the line
(8) and supplies a distillation column (9). A flow containing
hydrogen chloride, water and dichloropropanol in small amounts is
drawn off from the column (9) via the line (10). One part of this
flow is optionally recycled to the reactor (1) via the line (11). A
flow containing a mixture of dichloropropanol, hydrochloric acid
and water is drawn off from the bottom of the column (9) via the
line (22). A liquid flow in which the weight ratio between the
hydrogen chloride and the water is greater than or equal to (e) but
less than its value in the flow drawn off in (5) and the ratio
between the dichloropropanol and the water is higher than (d) (ABD
zone of the ternary diagram from FIG. 1) is drawn off from the
stripping machine (6) via the line (12) and supplies a container
(13) in which a flow of glycerol and/or glycerol esters and/or
monochloropropanediol and/or monochloropropanediol esters is
introduced via the line (14). A liquid flow, of which the
dichloropropanol/hydrogen chloride/water composition is in the BDG
zone of the ternary diagram from FIG. 1, is drawn off from the
container (13) via the line (15) and supplies a distillation column
(16). A flow comprising water and dichloropropanol is drawn off
from the top of the column (16) via the line (17). A flow
comprising water, dichloropropanol and hydrogen chloride is drawn
off from the bottom of the column (16) via the line (18). The line
(18) supplies a distillation column (19). A flow comprising water,
dichloropropanol and hydrogen chloride is drawn off from the top of
the column (19) via the line (20). The flow from the line (20) may,
completely or partly, be recycled to the reactor (1). A flow
comprising dichloropropanol is drawn off from the bottom of the
distillation column (19) via the line (21).
[0131] The dichloropropanol obtained in the flow (21) may be
purified, for example by distillation, in order to eliminate the
other compounds that constitute heavy compounds from the reaction
medium, such as the catalyst, glycerol monochlorohydrin and
chlorinated glycerol oligomers. The latter may be completely or
partly recycled to the reactor (1).
[0132] In a second combination of embodiments of the process
according to the invention, the same equipment as that which is
presented in FIG. 2 is used, except that in the liquid flow which
is continuously drawn off from the reactor (1) the weight ratio
between the hydrogen chloride and the water is greater than (e) and
the ratio between the dichloropropanol and the water is lower than
(d) (ADE zone of the ternary diagram from FIG. 1) and in the liquid
flow which is continuously drawn off from the container (13) the
weight ratio between the water and the dichloropropanol and the
weight ratio between the hydrogen chloride and the water are such
that the dichloropropanol/ hydrogen chloride/water composition is
in the DGF zone of the ternary diagram from FIG. 1.
[0133] In a third combination of embodiments of the process
according to the invention, the same procedure as in the second
embodiment is followed, except that: [0134] 1) in the liquid flow
which is continuously drawn off from the container (13) the weight
ratio between the water and the dichloropropanol and the weight
ratio between the hydrogen chloride and the water are such that the
dichloropropanol/hydrogen chloride/water composition is in the DEF
zone of the ternary diagram from FIGS. 1; and [0135] 2) the flow
drawn off from the bottom of the column (19) via the line (21)
contains water and hydrogen chloride.
[0136] In a fourth combination of embodiments of the process
according to the invention, the same procedure as in the second
embodiment is followed, except that: [0137] 1) in the liquid flow
which is continuously drawn off from the container (13) the weight
ratio between the water and the dichloropropanol and the weight
ratio between the hydrogen chloride and the water are such that the
dichloropropanol/hydrogen chloride/water composition is in the EFC
zone of the ternary diagram from FIG. 1; [0138] 2) the flow drawn
off from the top of the column (19) via the line (20) contains
water; and [0139] 3) the flow drawn off from the bottom of the
column (19) via the line (21) contains water and hydrogen
chloride.
[0140] In a fifth combination of embodiments of the process
according to the invention which is presented in FIG. 3, a first
reactor (26) is continuously supplied with glycerol, gaseous
hydrogen chloride and a catalyst respectively via the lines (23),
(24) and (25). The reactor is permanently kept under a partial
pressure of hydrogen chloride above the partial pressure of
hydrogen chloride in the water/hydrogen chloride azeotrope at the
reaction pressure. The total pressure is of 8 bar absolute.
[0141] A liquid flow is drawn off from the reactor (26) via the
line (27). This flow supplies a column (28) kept at a pressure of 8
bar absolute, this column possibly being composed only of a single
bottom section. Drawn off from the column (28) via the line (29) is
a flow that is very rich in hydrogen chloride and that contains a
little water and dichloropropanol. This flow may be completely or
partly recycled to the reactor (26) via the line (30). Drawn off
from the column (28) via the line (31) is a liquid flow containing
most of the organic compounds, and also water and hydrogen
chloride. The ratio of the weight concentration of hydrogen
chloride relative to the water in the flow from the line (31) is
0.16, which corresponds to the weight ratio of hydrogen chloride in
the water/hydrogen chloride azeotrope at a pressure of 8 bar
absolute. The flow (31) supplies a distillation column (32) kept
under a pressure of 0.1 bar absolute. A flow is drawn off from the
top of the column (32) via the line (33). This flow supplies a
settling tank (34) in which a light phase and a heavy phase are
separated. The light phase is drawn off from the settling tank (34)
via the line (36). A part of this light phase exiting the settling
tank (34), which essentially contains water, is conveyed back to
the column (32) via the line (35). The heavy phase is drawn off
from the settling tank (34) via the line (37). This phase
essentially contains dichloropropanol produced by the process.
Drawn off from the column (32) via the line (38) is a residue which
contains a mixture of water, hydrogen chloride, dichloropropanol
and also other constituents of the reaction medium. This mixture
may be completely or partly recycled to the reactor (26) via the
line (39). The non-recycled part constitutes a purge. The weight
ratio of the hydrogen chloride relative to the water in the flow
drawn off from the line (39) is that of the water/hydrogen chloride
azeotrope at a pressure of 0.1 bar, i.e. 0.3.
[0142] In a sixth combination of embodiments of the process
according to the invention which is presented in FIG. 4, a first
reactor (40) is continuously supplied with glycerol, gaseous
hydrogen chloride and a catalyst respectively via the lines (41),
(42) and (43). The reactor is permanently kept under a partial
pressure of hydrogen chloride above the partial pressure of
hydrogen chloride in the water/hydrogen chloride azeotrope at the
reaction pressure. The reaction pressure is higher than or equal to
2 bar absolute.
[0143] A flow is drawn off from the reactor (40), continuously or
in batch mode, via the line (44) in order to supply a flash
evaporator (45), in which almost all of the hydrogen chloride and
water contained in the flow (44) is vaporized. A gas flow is drawn
off from the flash evaporator (45) via the line (46), in which the
weight ratio of hydrogen chloride relative to water is greater than
that of the azeotropic water/hydrogen chloride composition, and a
reactor (47) is supplied with this flow. The reactor 47) is also
supplied with a flow containing glycerol via the line 48) and with
a flow drawn off from the column 55) via the line (57). A gas or
liquid flow is drawn off from the reactor via the line (50) and the
distillation column (51) is supplied with this flow. The weight
ratio of hydrogen chloride relative to water is less than that of
the azeotropic water/hydrogen chloride composition at the pressure
of the column (51). A flow is drawn off, from the column (51) via
the line (53), which contains water and dichloropropanol with a
hydrogen chloride content of less than 1 g/l. A flow is drawn off,
from the column (51) via the line (52), which contains, amongst
other things, hydrogen chloride, water and dichloropropanol, and
the reactor (47) is supplied with this flow. Another liquid flow is
drawn off from the reactor (47) via the line (49) and the reactor
(40) is supplied with this flow. Drawn off from the bottom of the
flash evaporator (45), and via the line (54), is a flow which is
practically free from hydrogen chloride, and the distillation
column (55) is supplied with this flow. Drawn off from the top of
the column (55), via the line (56), is a flow composed of
practically pure dichloropropanol. Drawn off from the bottom of the
column (55), via the line (57), is a flow comprising heavy
compounds that mostly contain glycerol monochloroydrin, catalyst,
unconverted glycerol and chlorinated ethers, and the reactor (47)
is supplied with this flow. A part of this flow (57) may be drawn
off to supply a purge.
[0144] In a seventh combination of embodiments of the process
according to the invention which is presented in FIG. 5, a second
reactor (60) is continuously supplied with a flow containing
glycerol and a flow containing a catalyst respectively via the
lines (58) and (59). The reactor is also supplied with a mixture
essentially composed of hydrogen chloride, water and
dichloropropanol via a recycling flow (73) and with a mixture
composed of glycerol, chloropropanediol, carboxylic acid and esters
via a recycling flow (78). The reactor operates at close to
atmospheric pressure. At least part of the gaseous phase from the
reactor (60) is drawn off to supply the distillation column (64). A
flow is drawn off continuously from the reactor (60) via the line
(61) and an evaporator (62) is supplied with this flow. In the
evaporator (62), almost all of the hydrogen chloride and water
contained in the flow (61) is vaporized. A gas flow is drawn off
from the evaporator (62) via the line (63) and a distillation
column (64) is supplied with this flow. The weight ratio of
hydrogen chloride relative to water in the flow (63) is less than
that of the azeotropic water/hydrogen chloride composition at the
pressure of the distillation column (64). A flow is drawn off, from
the column (64) via the line (65), which contains water and
dichloropropanol with a hydrogen chloride content of less than 1
g/l. A first flow is drawn off, from the base of the column (64)
via the line (66) and the reactor (60) is supplied with this flow.
A second flow is drawn off from the column (64) via the line (69)
and a first reactor (68) is supplied with this flow so as to adjust
the water content in the reaction mixture of the reactor (68). A
liquid flow is drawn off from the evaporator (62) via the line (67)
and the reactor (68) is supplied with this flow. The reactor (68)
is also supplied with a flow containing gaseous hydrogen chloride
via the line (70). The reactor (68) is permanently kept under a
partial pressure of hydrogen chloride above the partial pressure of
hydrogen chloride in the water/hydrogen chloride azeotrope at the
reaction temperature in the reactor (68). A liquid flow is drawn
off from the reactor (68) via the line (71) and an evaporator (72)
is supplied with this flow. Drawn off from the evaporator (72), via
the line (73), is a gas flow essentially composed of hydrogen
chloride, water and a little dichloropropanol, and the reactor (60)
is supplied with this flow. Drawn off from the evaporator (72) via
the line (74) is a liquid flow which is practically free from
hydrogen chloride. This flow (74) supplies the column (75). Drawn
off from the top of the column (75), via the line (76), is a flow
containing practically pure dichloropropanol. Drawn off from the
bottom of the column (75), via the line (77), is a flow which
contains the heavy compounds from the reaction medium. These heavy
compounds mostly contain glycerol monochlorohydrin, catalyst,
unconverted glycerol and chlorinated ethers. A large part of this
flow is recycled to the reactor (60) via the line (78). Another
part of the flow drawn off from the bottom of the column (75) via
the line (77) is conveyed to the reactor (68) via the line (79) so
as to complete the conversion of chloropropanediol to
dichloropropanol. Part of the flow drawn off from the bottom of the
column (75) via the line (77) may supply a purge via the line
(80).
[0145] In an eighth combination of embodiments of the process
according to the invention, the same procedure as in the seventh
combination of embodiments is followed, except that the liquid flow
drawn off from the bottom of the column (64) is not conveyed to the
reactor (68) via the line (69).
[0146] In a ninth combination of embodiments of the process
according to the invention, the same procedure as in the seventh
combination of embodiments is followed, except that the liquid flow
drawn off from the bottom of the column (75) is not conveyed to the
reactor (68) via the line (79).
[0147] In a tenth combination of embodiments of the process
according to the invention, the same procedure as in the seventh
combination of embodiments is followed, except that the liquid flow
collected at the bottom of the column (64) is not conveyed to the
reactor (68) via the line (69), and except that the liquid flow
collected at the bottom of the column (75) is not conveyed to the
reactor (68) via the line (79).
[0148] In an eleventh combination of embodiments of the process
according to the invention, the same procedure as in the eighth
combination of embodiments is followed, except that a gaseous phase
is not drawn off from the reactor (60).
[0149] In a twelfth combination of embodiments of the process
according to the invention, the same procedure as in the ninth
combination of embodiments is followed, except that a gaseous phase
is not drawn off from the reactor (60).
[0150] In a thirteenth combination of embodiments of the process
according to the invention, the same procedure as in the tenth
combination of embodiments is followed, except that a gaseous phase
is not drawn off from the reactor (60).
[0151] The numbers cited between brackets in the remainder of the
description refer to FIG. 5.
[0152] The invention also relates to a process for manufacturing
dichloropropanol according to which glycerol and/or
monochloropropanediol are reacted with hydrogen chloride, in a
liquid reaction medium, which is in contact with a gaseous phase,
in at least two reactors arranged in a loop, and under a partial
pressure of hydrogen chloride in the first reactor (68) which is
greater than the partial pressure of hydrogen chloride in the
second reactor (60).
[0153] In one preferred operating mode, this process comprises, in
addition, at least two separation operations, including one in at
least one evaporator (72) in which the value of the partial
pressure of hydrogen chloride is between the partial pressure of
hydrogen chloride in the second reactor (60) and the partial
pressure of hydrogen chloride in the first reactor (68) and
including another in at least one distillation column (75), and in
this process: [0154] the first reactor (68) is supplied with a
first gas flow (70) containing hydrogen chloride and the second
reactor with a first liquid flow (58) containing glycerol, and
optionally water and hydrogen chloride, and a second liquid flow
(59) containing a catalyst; [0155] drawn off from the first reactor
(68) is a third liquid flow (71) and the evaporator (72) is
supplied with this third liquid flow; [0156] drawn off from the
evaporator (72) is a second gas flow (73) in which the weight ratio
of hydrogen chloride with respect to water is greater than that of
the azeotropic water/hydrogen chloride composition at total
pressure in the evaporator (72) and the second reactor (60) is
supplied with this second gas flow, drawn off from the evaporator
(72) is a fourth liquid flow (74) of which the hydrogen chloride
content is less than the hydrogen chloride content in the liquid
reaction medium of the first reactor (68), and the first
distillation column (75) is supplied with this fourth liquid flow
(74); [0157] drawn off from the second reactor (60) is a fifth
liquid flow (61=67) which supplies the first reactor (68), the
evaporator (62) is not present and the lines (61) and (67) form a
single line; [0158] drawn off from the first distillation column
(75) is a third gas flow (76) which mostly contains
dichloropropanol and a sixth liquid flow (77) which mostly contains
reaction intermediates such as monochloropropanediol, the catalyst
and reaction by-products such as partially chlorinated glycerol
oligomers, and drawn off from the sixth liquid flow (77) is a
seventh liquid flow (80) which constitutes a purge.
[0159] In a first variant of this preferred operating mode, the
process comprises at least one additional separation step in a
second distillation column (64) which is supplied with a fourth gas
flow (81) drawn off from the second reactor (60), and drawn off
from which second column is a fifth gas flow (65) which mostly
contains water and dichloropropanol and an eighth liquid flow (66)
which supplies the second reactor (60).
[0160] In a second variant of this preferred operating mode, the
process comprises two additional separation steps, including one in
a second evaporator (62) and including another in a second
distillation column (64). The second evaporator (62) is supplied
with the fifth liquid flow (61) and drawn off from the second
evaporator (62) is a sixth gas flow (63) and a ninth liquid flow
(67). The first reactor (68) is supplied with the ninth liquid flow
(67). The second distillation column (64) is supplied with the
sixth gas flow (63) and drawn off from the second distillation
column (64) is an eighth liquid flow (66) which supplies the
reactor (60).
[0161] In a third variant of this preferred operating mode, the
procedure from the second variant is followed and in addition the
second distillation column (64) is supplied with a gas flow (81)
drawn off from the second reactor (60).
[0162] In supplementary variants, the procedure from the second or
third variants is followed and, in addition, drawn off from the
sixth liquid flow (77) is a tenth liquid flow (78) and the second
reactor (60) is supplied with this flow, and/or drawn off from the
sixth liquid flow (77) is an eleventh liquid flow (79) and the
first reactor (68) is supplied with this flow, and/or drawn off
from the second distillation column (64) is a twelfth liquid flow
(69) and the first reactor (68) is supplied with this flow.
[0163] The invention also relates to an installation for
manufacturing dichloropropanol comprising at least two glycerol
chlorination reactors arranged in a loop, at least one first
reactor supply line (70), at least one second reactor supply line
(58,59), and at least one line connecting the first and second
reactor (61=67).
[0164] This installation preferably comprises, in addition, at
least one evaporator (72) and at least one distillation column
(75), at least one line (71) connecting the first reactor (68) and
the evaporator (72), at least one line (74) connecting the bottom
of the evaporator (72) and the first column (75), at least one line
(73) connecting the top of the evaporator (72) and the second
reactor (60), at least one outlet line (76) at the top of the first
distillation column (75) and at least one outlet line (77) at the
bottom of the first distillation column.
[0165] This preferred installation may comprise, in addition, a
second distillation column (64), and at least two lines (66) and
(81) connecting the bottom of the second distillation column (64)
to the second reactor (60).
[0166] This preferred installation may comprise, in addition, a
second evaporator (62) and at least one line (61) connecting the
second reactor (60) to the second evaporator (62), a line (67)
connecting the bottom of the second evaporator to the first reactor
(68), at least one line (63) connecting the top of the second
evaporator to the second distillation column (64).
[0167] This preferred installation may moreover comprise, in
addition, at least one line (69) connecting the bottom of the
second distillation column (64) and the first reactor (68), and/or
at least one line (79) connecting the bottom of the first
distillation column (75) and the first reactor (68), and/or at
least one line (78) connecting the bottom of the first distillation
column (75) and the second reactor (60).
* * * * *