U.S. patent application number 10/536498 was filed with the patent office on 2006-04-13 for continuous methods and reactor used for the production of alkylamines.
This patent application is currently assigned to BASF Aktiengesellschaft. Invention is credited to Marco Bosch, Thomas Krug, Johann-Peter Melder, Roderich Rottger, Bernd Stein, Theodor Weber.
Application Number | 20060079718 10/536498 |
Document ID | / |
Family ID | 32240472 |
Filed Date | 2006-04-13 |
United States Patent
Application |
20060079718 |
Kind Code |
A1 |
Bosch; Marco ; et
al. |
April 13, 2006 |
Continuous methods and reactor used for the production of
alkylamines
Abstract
In the continuous process for preparing alkylamines by reacting
C.sub.1-4-alkanols with ammonia in the gas phase in the presence of
a shape-selective fixed-bed catalyst in a cooled reactor, the
shape-selective fixed-bed catalyst is present in a single
contiguous fixed bed in the reactor and tubes through which
coolants are passed run within the fixed bed to regulate the
temperature of the fixed bed.
Inventors: |
Bosch; Marco; (Mannheim,
DE) ; Rottger; Roderich; (Mannheim, DE) ;
Stein; Bernd; (Alsbach-Hahnlein, DE) ; Krug;
Thomas; (Worms, DE) ; Melder; Johann-Peter;
(Bohl-Iggelheim, DE) ; Weber; Theodor;
(Ludwigshafen, DE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
BASF Aktiengesellschaft
Patents, Trademarks and Licenses
Ludwigshafen
DE
D-67056
|
Family ID: |
32240472 |
Appl. No.: |
10/536498 |
Filed: |
November 24, 2003 |
PCT Filed: |
November 24, 2003 |
PCT NO: |
PCT/EP03/13170 |
371 Date: |
May 25, 2005 |
Current U.S.
Class: |
564/478 |
Current CPC
Class: |
C07C 209/16 20130101;
B01J 2208/0053 20130101; B01J 8/0285 20130101; B01J 8/0221
20130101; B01J 2208/00353 20130101; B01J 2208/00132 20130101; C07C
209/16 20130101; C07C 211/04 20130101 |
Class at
Publication: |
564/478 |
International
Class: |
C07C 209/16 20060101
C07C209/16 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 26, 2002 |
DE |
102 55 294.0 |
Claims
1. A continuous process for preparing alkylamines by reacting
C.sub.1-4-alkanols with ammonia in the gas phase in the presence of
a shape-selective fixed-bed catalyst in a cooled reactor, wherein
the shape-selective fixed-bed catalyst is present in a single
contiguous fixed bed in the reactor and tubes through which
coolants are passed run within the fixed bed to regulate the
temperature of the fixed bed.
2. A process as claimed in claim 1, wherein cooling is carried out
by means of boiling water cooling.
3. A process as claimed in claim 1, wherein the pressure in the
coolant is from 40 to 220 bar and the pressure in the fixed
catalyst bed is from 10 to 50 bar.
4. A reactor for the reaction of C.sub.1-4-alkanols with ammonia in
the gas phase for preparing alkylamines, which comprises a
shape-selective fixed-bed catalyst which is present as a single
contiguous fixed bed in the reactor and through whose interior
tubes through which a coolant can be passed run.
5. canceled
6. A continuous process for preparing alkylamines by reacting
C.sub.1-4-alkanols with ammonia in the gas phase in the presence of
a shape-selective fixed-bed catalyst in a reactor, wherein part of
the C.sub.1-4-alkanols, the ammonia or mixtures thereof is
introduced in liquid form into the reactor in such a way that
vaporization takes place on the fixed catalyst bed.
7-10. (canceled)
11. A continuous process for preparing alkylamines by reacting
C.sub.1-4-alkanols with ammonia in the gas phase in the presence of
a shape-selective fixed-bed catalyst in a reactor, wherein 30-90%
of the C.sub.1-4-alkanols, the ammonia or mixtures thereof
introduced into the reactor is fed into the fixed catalyst bed at
least one point at which a previously reacted reaction mixture of
C.sub.1-4-alkanols and ammonia which has a temperature higher than
that of the C.sub.1-4-alkanols, ammonia or mixtures thereof fed in
is present.
12. A continuous process for preparing alkylamines by reacting
C.sub.1-4-alkanols with ammonia in the gas phase in the presence of
a shape-selective fixed-bed catalyst in a reactor, wherein a heat
transfer medium which is inert toward the C.sub.1-4-alkanols and
ammonia and the reaction products and/or does not significantly
affect the activity and selectivity of the catalyst is additionally
fed into the fixed catalyst bed by addition to the reactor feed
mixture.
13. A process as claimed in claim 12, wherein the heat transfer
medium is or comprises water.
14. A process as claimed in claim 11 carried out in a reactor for
the reaction of C.sub.1-4-alkanols with ammonia in the gas phase
for preparing alkylamines, which comprises a shape-selective
fixed-bed catalyst which is present as a single contiguous fixed
bed in the reactor and through whose interior tubes through which a
coolant can be passed run.
15. A process as claimed in claim 6 carried out in a reactor for
the reaction of C.sub.1-4-alkanols with ammonia in the gas phase
for preparing alkylamines, which comprises a shape-selective
fixed-bed catalyst which is present as a single contiguous fixed
bed in the reactor and through whose interior tubes through which a
coolant can be passed run.
16. A process as claimed in claim 12 carried out in a reactor for
the reaction of C.sub.1-4-alkanols with ammonia in the gas phase
for preparing alkylamines, which comprises a shape-selective
fixed-bed catalyst which is present as a single contiguous fixed
bed in the reactor and through whose interior tubes through which a
coolant can be passed run.
17. A process as claimed in claim 11 carried out in a reactor for
the reaction of C.sub.1-4-alkanols with ammonia in the gas phase
for preparing alkylamines, which comprises a shape-selective
fixed-bed catalyst which is present as a single contiguous fixed
bed in the reactor and through whose interior tubes through which a
coolant can be passed run, wherein the C.sub.1-4-alkanols, ammonia
or mixtures thereof introduced into the reactor are fed in radially
to the longitudinal axis of the reactor.
18. A process as claimed in claim 6 carried out in a reactor for
the reaction of C.sub.1-4-alkanols with ammonia in the gas phase
for preparing alkylamines, which comprises a shape-selective
fixed-bed catalyst which is present as a single contiguous fixed
bed in the reactor and through whose interior tubes through which a
coolant can be passed run, wherein the C.sub.1-4-alkanols, ammonia
or mixtures thereof introduced into the reactor are fed in radially
to the longitudinal axis of the reactor.
19. A process as claimed in claim 12 carried out in a reactor for
the reaction of C.sub.1-4-alkanols with ammonia in the gas phase
for preparing alkylamines, which comprises a shape-selective
fixed-bed catalyst which is present as a single contiguous fixed
bed in the reactor and through whose interior tubes through which a
coolant can be passed run, wherein the C.sub.1-4-alkanols, ammonia
or mixtures thereof introduced into the reactor are fed in radially
to the longitudinal axis of the reactor.
Description
[0001] The present invention relates to a reactor and a process for
preparing alkylamines by reacting C.sub.1-4-alkanols with ammonia
in the gas phase in the presence of a shape-selective fixed-bed
catalyst.
[0002] In particular, the invention relates to the reaction of
methanol with ammonia to produce methylamines, preferably in a
selectivity to dimethylamine (DMA) which is greater than that
resulting from the thermodynamic equilibrium.
[0003] The classical synthesis of monomethylamine (MMA),
dimethylamine (DMA) and trimethylamine (TMA) is carried out from
ammonia and methanol in the gas phase over amorphous
non-shape-selective silica-alumina (mixed forms of aluminum and
silicon oxides) at pressures of from 15 to 50 bar. When relatively
high temperatures (350 to about 500.degree. C.) are employed,
thermodynamic equilibrium is established or approximately
established over these heterogeneous catalysts provided that the
residence time in the reactor at the given pressure and given feed
temperature is sufficient. A characteristic of these "equilibrium
catalysts" is a proportion of trimethylamine in the output from the
reactor of from 40 to 60% by weight based on the sum of
monomethylamine, dimethylamine and trimethylamine. The product
distribution is dependent on the temperature and on the N/C ratio.
The proportion of trimethylamine in the product mixture can be
reduced when a relatively large excess of ammonia (relatively large
N/C ratio) is present in the reaction mixture. If the proportion of
monomethylamine and/or dimethylamine in the desired product mixture
taken off after the known work-up is greater than that
corresponding to the output from the reactor, both the excess
trimethylamine and the unreacted ammonia have to be recirculated to
the reactor, resulting in large circulations of ammonia and
trimethylamine.
[0004] The worldwide consumption of TMA is from about 10 to 20% by
weight of the total amount of methylamines consumed. It is
desirable to increase the proportion of DMA and MMA without
recirculation of the reaction mixture. This is achieved by the use
of shape-selective zeolite catalysts such as mordenite, ZK-5, Rho,
erionite, chabazite, ferrierite and clinoptilolite at from 250 to
400.degree. C. This gives a product mixture comprising
predominantly dimethylamine and monomethylamine and containing only
little trimethylamine. According to EP-A-1 077 084, a methanol
conversion of 99.2% and an MMA/DMA/TMA weight ratio of 32/52/16 in
the product mixture are measured over a shape-selective H-mordenite
catalyst at an N/C ratio of 1.9, a reaction pressure of 20 bar, a
temperature of 320.degree. C. and a GHSV of 2500 h.sup.-1 after 6
hours. If dimethylamine forms the major part of the desired product
mixture taken off after the known work-up, the quantities which
have to be separated off by distillation and recirculated to the
reactor can be reduced significantly compared to the synthesis over
non-shape-selective "equilibrium catalysts".
[0005] Studies on the selectivity to dimethylamine when using
shape-selective mordenite catalysts have shown that the proportion
of DMA is about 60% by weight at 320.degree. C. and an N/C ratio of
from 1.2 to 2.0. Since the amount of ammonia can be varied without
altering the selectivity, it is desirable to set a small N/C ratio,
since then less ammonia has to be separated off by distillation and
recirculated to the reactor or a second reactor using an
"equilibrium catalyst". The use of N/C ratios of less than 0.8
should be avoided, since the formation of by-products which
deactivate the catalyst (carbonization) occurs.
[0006] The operating life of the zeolite catalyst is better, the
smaller the difference between outlet temperature and inlet
temperature of the reactor, preferably less than 60.degree. C.
Excessively high output temperatures or "hot spots" in the reactor
lead to a decrease in the proportion of DMA in the product mixture
and an increase in the proportion of TMA. U.S. Pat. No. 4,398,041
describes a process in which the reactor feed is diluted with
excess ammonia to reduce the temperature increase in the
adiabatically operated reactor. The large excess of ammonia (N/C
ratio of .gtoreq.2.0) results in the considerable disadvantage that
large amounts of ammonia have to be separated off by distillation
and recirculated to the reactor.
[0007] For this reason, a mode of operation in which all or part of
the heat generated by the reaction is removed by means of heat
exchangers installed in the reactor in order to limit the
difference between outlet temperature and inlet temperature is more
advantageous in the synthesis of methylamines using shape-selective
zeolite catalysts. EP-B-0 763 519 describes the synthesis of
methylamines in one or more reactors which is/are divided into two
or more individual beds which are arranged in parallel or in
series. Heat removal is achieved by cooling the reaction mixture
between these individual beds. The parallel arrangement of
individual beds between which a heat-removing medium is present is
achieved, for example, by means of shell-and-tube reactors.
[0008] The synthesis of methylamines in shell-and-tube reactors is
also described in EP-A-0 593 086.
[0009] In shell-and-tube reactors, the catalyst bed and the
reaction mixture are located within the tubes and the cooling
medium is present outside the tubes. In the synthesis of
methylamines, the pressure in the reaction medium is generally from
15 to 25 bar. At a synthesis temperature of 320.degree. C., the
pressure of the cooling medium is about 100 bar when boiling water
is used for cooling. The design pressure of the reactor wall of a
shell-and-tube reactor therefore has to be about 100 bar.
[0010] It is an object of the present invention to provide reactors
and processes for preparing alkylamines by reacting alkanols with
ammonia in the gas phase in the presence of shape-selective
fixed-bed catalysts, which avoid the disadvantages of the existing
processes and, in particular, require a smaller outlay in terms of
apparatus.
[0011] We have found that this object is achieved by a continuous
process for preparing alkylamines by reacting C.sub.1-4-alkanols
with ammonia in the gas phase in the presence of a shape-selective
fixed-bed catalyst in a cooled reactor, wherein the shape-selective
fixed-bed catalyst is present in a single contiguous fixed bed in
the reactor and tubes through which coolants are passed run within
the fixed bed to regulate the temperature of the fixed bed.
[0012] It has been found that the configuration of a fixed-bed
reactor for the synthesis of alkylamines can be chosen so that the
catalyst bed forms a single contiguous bed in which or between
which tubes within which the cooling medium is present are located.
The advantage is that the design pressure of the cylindrical
reactor wall and the reactor caps only has to correspond to the
product-side pressure. Only the tubes in which the cooling medium
is present have to be designed for the higher pressure of the
cooling medium. The facilities for distributing, collecting and
leading away the cooling medium likewise have to be designed for
this pressure. The wall thickness of the reactor wall can be
significantly reduced in this way, which leads to significantly
lower costs and to a significantly lower weight of the reactor. The
tubes for the cooling medium are advantageously used in coiled
form, since in this design stresses due to different thermal
expansions of the wall of the apparatus and cooling tubes are
virtually insignificant. A combination of this reactor design with
shape-selective catalysts gives particular advantages.
[0013] According to the present invention, the tubes can have any
suitable or desired geometry. The tubes preferably have a cross
section which does not have any corners. For example, the tube
cross section can be circular or ellipsoidal. The tube diameter is
preferably from 1 to 5 cm.
[0014] Suitable reactors are described, for example, in EP-A-0 534
195. They can be used, inter alia, for the preparation of
methylamines from methanol and ammonia.
[0015] Any suitable coolant which allows efficient uptake and
removal of heat and efficient transport of the cooling medium can
be passed through the tubes. Suitable coolants are, for example,
water, aqueous solutions containing, for example, glycols or salt
melts. Cooling is preferably carried out by means of boiling water
cooling, so that the coolant is water or comprises predominantly
water.
[0016] The pressure in the coolant is preferably from 40 to 220
bar, particularly preferably from 60 to 150 bar, and the pressure
in the fixed catalyst bed is from 10 to 50 bar, particularly
preferably from 15 to 30 bar. For example, the product-side
pressure in the reactor can be about 25 bar, while the pressure of
the cooling medium can be about 100 bar in the case of boiling
water cooling.
[0017] The geometry of the arrangement of the coolant tubes in the
reactor can be chosen freely, as long as efficient heat removal is
achieved. The geometry is preferably chosen so that the temperature
distribution in the fixed catalyst bed is very uniform. The design
and operation of are preferably such that the difference between
outlet temperature and inlet temperature of the reactor is less
than 60.degree. C., particularly preferably less than 35.degree.
C.
[0018] Suitable reactors are, for example, Linde isothermal
reactors or comparable nickel reactors as are also described in
DE-A-34 14 717 and EP-A-0 534 195. They are usually operated
isothermally.
[0019] Suitable dimensions of the reactor and the tubes for the
coolant are known to those skilled in the art.
[0020] The invention also provides a reactor for the reaction of
C.sub.1-4-alkanols with ammonia in the gas phase for preparing
alkylamines, which comprises a shape-selective fixed-bed catalyst
which is present as a single contiguous fixed bed in the reactor
and through whose interior tubes through which a coolant can be
passed run.
[0021] The reactor is preferably made of metallic materials such as
stainless steel. The wall thicknesses are chosen so that the
above-described pressure conditions are possible.
[0022] In the reactor, the catalyst bed forms a single contiguous
bed. This means that there are no individual regions or islands in
the catalyst bed in the reactor but instead the entire bed is
contiguous.
[0023] The object of the invention is also achieved by a continuous
process for preparing alkylamines by reacting C.sub.1-4-alkanols
with ammonia in the gas phase in the presence of a shape-selective
fixed-bed catalyst in a reactor in which part of the
C.sub.1-4-alkanols, the ammonia or mixtures thereof introduced into
the reactor is fed into the fixed catalyst bed at at least one
point at which a previously reacted reaction mixture of
C.sub.1-4-alkanols and ammonia which has a temperature higher than
that of the C.sub.1-4-alkanols, ammonia or mixtures thereof fed in
is present.
[0024] In this embodiment, part of the reactor feed mixture or part
of the individual components fed in is not introduced at the inlet
of the reactor but is instead added to the previously partially
reacted reaction mixture in the interior of the reactor, preferably
in the first 2/3 of the catalyst bed. The temperature of the
portions added in the interior is lower than the temperature of the
previously partially reacted reaction mixture at the point in the
reactor at which the addition takes place. Preference is given to
from 30 to 90%, particularly preferably from 50 to 80%, of the
starting materials to be introduced into the reactor being
introduced not at the inlet of the reactor but in the interior of
the reactor. The temperature of the added starting materials is
preferably at least 40.degree. C., particularly preferably at least
70.degree. C., lower than the temperature prevailing in the
catalyst bed at the point of addition. The introduction can be
carried out at one or more points along the catalyst bed. The
introduction is preferably regulated so that a largely homogeneous
temperature distribution is established in the entire catalyst bed.
The amount of starting materials fed into the catalyst bed can thus
be used to take up the energy of reaction which is liberated.
[0025] Furthermore, the object of the present invention is achieved
by a continuous process for preparing alkylamines by reacting
C.sub.1-4-alkanols with ammonia in the gas phase in the presence of
a shape-selective fixed-bed catalyst in a reactor, in which part of
the C.sub.1-4-alkanols, the ammonia or mixtures thereof is
introduced in liquid form into the reactor in such a way that
vaporization takes place on the fixed catalyst bed. In this
embodiment, part of the reactor feed mixture or part of the
individual components being fed in is introduced in liquid form.
The liquids vaporize in the reactor or on the fixed-bed catalyst.
Preference is given to from 5 to 70%, particularly preferably from
10 to 50%, of the total starting materials to be fed into the
reactor being introduced in liquid form. Suitable devices for
feeding in the liquid starting materials are known. The fixed
catalyst bed can be cooled by take up of heat at the point of
addition.
[0026] Furthermore, the object of the present invention is achieved
by a continuous process for preparing alkylamines by reacting
C.sub.1-4-alkanols with ammonia in the gas phase in the presence of
a shape-selective fixed-bed catalyst in a reactor, wherein a heat
transfer medium which is inert toward the C.sub.1-4-alkanols and
ammonia and the reaction products and/or does not significantly
affect the activity and selectivity of the catalyst is additionally
fed into the fixed catalyst bed. Here, one or more other components
are added to the reactor feed mixture in an amount which is able to
take up part of the heat generated in the reaction. The added
component is chemically inert toward the other components in the
synthesis of alkylamines and/or does not influence the selectivity
of the reaction. It preferably has no effect or no significant
effect on the activity and selectivity of the catalyst. For
example, water or an aqueous solution having a water content of at
least 50%, preferably at least 80%, is used as heat transfer
medium.
[0027] The amount of heat transfer medium added depends on the
practical requirements of heat removal in the reactor. The heat
transfer medium can be separated off from the product stream in a
simple manner by suitable methods such as distillation.
[0028] The process of the present invention is carried out using
C.sub.1-4-alkanols, preferably C.sub.1-2-alkanols, in particular
methanol, which are reacted with ammonia. The N/C ratio, i.e. the
ratio of the number of N atoms to C atoms, when methanol is used is
preferably from 0.8 to 3.5, particularly preferably from 1.0 to
2.5, in particular from 1.2 to 2.0. According to the present
invention, this makes it possible to prevent relatively large
ammonia recycled streams occurring. In addition, the formation of
by-products which can deactivate the catalyst can be prevented.
[0029] According to the present invention, shape-selective
catalysts, in particular zeolites, are used. It is also possible to
use silicoaluminophosphates (SAPOs). Examples of suitable
shape-selective catalysts are mordenite, ZK-5, Rho-zeolite,
erionite, chabazite, ferrierite, clinoptilolite, SAPO-34, ZSM-5,
ZSM-11, ZSM-21, ZSM-35, NU-85, offretite, Y-zeolite and further
catalysts as are described in Catalysis Today 37 (1997), pages 71
to 102, especially Table 4 on page 76. The other shape-selective
catalysts mentioned in this reference can also be used. As regards
modified zeolite catalysts (mordenites), reference may be made to
U.S. Pat. No. 4,485,261, U.S. Pat. No. 4,578,516, U.S. Pat. No.
4,582,936 and EP-A-0 342 999. These are modified zeolites which are
derived from natural or synthetic mordenites and have been
chemically modified to adjust the cation content, in particular the
content of alkali metal ions and alkaline earth metal ions, and
have subsequently been treated with steam. Further suitable
mordenite catalysts are disclosed in EP-A-1 077 084. That document,
like U.S. Pat. No. 4,398,041, EP-A-0 593 086 and EP-A-0 763 519
indicates suitable reaction conditions. When shape-selective
zeolite catalysts are used, the reaction is preferably carried out
in the temperature range from 200 to 500.degree. C., particularly
preferably from 250 to 400.degree. C. The reaction pressure is
preferably from 5 to 50 bar, particularly preferably from 10 to 40
bar, in particular from 15 to 30 bar.
[0030] The space velocity over the catalyst (GHSV) is preferably
from 250 to 5000 standard l/l.sub.cath.
[0031] According to the present invention, the catalyst is used in
the form of a fixed bed made up of catalyst particles/shaped
bodies. The catalyst particles can have any geometry, for example
extrudates, pellets, prills or granules. The catalyst can consist
entirely of active component or can contain from 1 to 60% by weight
of binder. Customary binders are oxides of the elements aluminum,
silicon, titanium and zirconium and also clays such as
montmorillonite and kaolin.
[0032] Various embodiments of the present invention have been
described above. These embodiments can also be combined with one
another. For example, the catalyst arrangement according to the
present invention and the introduction of starting materials or
cooling media at various points in the reactor can be combined with
one another. The introduction of starting materials and cooling
media can also be combined.
[0033] The C.sub.1-4-alkanols, ammonia or mixtures thereof
introduced into the reactor can be fed in radially to the
longitudinal axis of the reactor, i.e. centripedally. Such an
embodiment is described, for example, in EP-A-0 534 195.
[0034] Preference is given to a reaction in which the difference
between inlet temperature and outlet temperature is less than
60.degree. C., preferably less than 35.degree. C., the N/C ratio is
in the range from 0.8 to 3.5, preferably from 1.0 to 2.5, in
particular from 1.2 to 2.0, and shape-selective zeolite catalysts
are used.
[0035] The process of the present invention makes it possible, in
particular, to prepare methylamines from methanol and ammonia with
a high selectivity to dimethylamine.
* * * * *