CA1210411A - Continuous process for preparing alkanolamines - Google Patents
Continuous process for preparing alkanolaminesInfo
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- CA1210411A CA1210411A CA000405478A CA405478A CA1210411A CA 1210411 A CA1210411 A CA 1210411A CA 000405478 A CA000405478 A CA 000405478A CA 405478 A CA405478 A CA 405478A CA 1210411 A CA1210411 A CA 1210411A
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- Prior art keywords
- reaction
- mixture
- ammonia
- reactor
- alkylene oxide
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
CONTINUOUS PROCESS FOR PREPARING
ALKANOLAMINES
ABSTRACT OF THE DISCLOSURE
A continuous process is provided for preparing alkanolamines having a high yield of monoalkanolamine which comprises continuously reacting a flowing stream of a homogeneous mixture of an alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 maintained in a single supercritical fluid phase in a plug-flow reactor at temperatures above about 100°C and at pressures high enough to maintain the reaction mixture in a single supercritical fluid phase having a density of at least 15 lbs./cu.ft. for the time necessary to form an alkanolamine product mixture containing predominately monoalkanolamine.
S P E C I F I C A T I O N
ALKANOLAMINES
ABSTRACT OF THE DISCLOSURE
A continuous process is provided for preparing alkanolamines having a high yield of monoalkanolamine which comprises continuously reacting a flowing stream of a homogeneous mixture of an alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 maintained in a single supercritical fluid phase in a plug-flow reactor at temperatures above about 100°C and at pressures high enough to maintain the reaction mixture in a single supercritical fluid phase having a density of at least 15 lbs./cu.ft. for the time necessary to form an alkanolamine product mixture containing predominately monoalkanolamine.
S P E C I F I C A T I O N
Description
-~2~!4~L
131~0 BA~KGR3UND OF THE IN~ENTION
This invention relates to a process ror the preparation of alkanolamines and, more particularly, to a continuous process for preparing alkanolamines with high yields of monoalkanolamine by the reaction of alkylene oxides with a large excess of ammonia wherein the reaction mixture is maintained in a single phase as a supercriti~-al fluid.
It is known that alkanolamines, which are used in a variety of commercial applications such as emulsification agen~s ror soaps and cosmetics and as a starting material for the production of raw materials for detergents, wetting agen~s, emuLsifiers, textile auxiliaries and the like, can be obtained by the reaction of alkylene oxides with ammonla or amlnes, the yield of alkanolamines being a mixture of mono; di-; and trialkanolamine with, generally e~ual relative proportions of the ~hree alkanolamines being frequently ootained. Th~ relative proportions of these three alkanolamines in the product mixture, however, are known to depend on the relative quantities o~ alkylene oxide and ammonia that are reacted and processes have heretofore been used or suggested for achieving higher yields of one or more of the alkanolamines in the mixture which involve varying the proportion of such reactants, such aSs increasing the amount of ammonia relative to the alkylene oxide to ob~ain increased yields of monoalkanolaminet as well as by other process changesO
131~0 BA~KGR3UND OF THE IN~ENTION
This invention relates to a process ror the preparation of alkanolamines and, more particularly, to a continuous process for preparing alkanolamines with high yields of monoalkanolamine by the reaction of alkylene oxides with a large excess of ammonia wherein the reaction mixture is maintained in a single phase as a supercriti~-al fluid.
It is known that alkanolamines, which are used in a variety of commercial applications such as emulsification agen~s ror soaps and cosmetics and as a starting material for the production of raw materials for detergents, wetting agen~s, emuLsifiers, textile auxiliaries and the like, can be obtained by the reaction of alkylene oxides with ammonla or amlnes, the yield of alkanolamines being a mixture of mono; di-; and trialkanolamine with, generally e~ual relative proportions of the ~hree alkanolamines being frequently ootained. Th~ relative proportions of these three alkanolamines in the product mixture, however, are known to depend on the relative quantities o~ alkylene oxide and ammonia that are reacted and processes have heretofore been used or suggested for achieving higher yields of one or more of the alkanolamines in the mixture which involve varying the proportion of such reactants, such aSs increasing the amount of ammonia relative to the alkylene oxide to ob~ain increased yields of monoalkanolaminet as well as by other process changesO
- 2 -There is disclosed, for example, in U.S. Patent No. 2,196,55~ to H. M. Guin~t a process for preparing mono-hydroxylalkylamines with yields of 90%-95~ by reacting at least 30 parts by weight of ammonia with one part of alkylene oxide in a liquid phase reaction.
Rela~ively dilute a~ueous ammonia solutions are em~loyed and the patent discloses that steam generated during conoentration of the reaction product mixture is used for heating subsequent reaction product mixtures to sapara~e a~nonia gas thererrom, thus reducing tne neat energy requirements for the process. Another process for preparing al~anolamines with extremely high yields of monoalkanolamines and only small amounts of the di-and trialkanolamines oy reacting alkylene oxide witn large excess amounts of ammonia in a li~uid phase reaction sys~em is disclosed in U.S. Patent No.
Rela~ively dilute a~ueous ammonia solutions are em~loyed and the patent discloses that steam generated during conoentration of the reaction product mixture is used for heating subsequent reaction product mixtures to sapara~e a~nonia gas thererrom, thus reducing tne neat energy requirements for the process. Another process for preparing al~anolamines with extremely high yields of monoalkanolamines and only small amounts of the di-and trialkanolamines oy reacting alkylene oxide witn large excess amounts of ammonia in a li~uid phase reaction sys~em is disclosed in U.S. Patent No.
3,697,598 to Weibull et al. The molar ratio of ammonia relative to al~ylene oxide used in the process is within the range of 10:1 to 80:1 and tha reaction is carried out in tne presence of a cation excAange resin catalyst. The process o~ the patent is described as being a continuous process whicn is capable of being run isothermally or, preferably, adiabatically at temperatures in the range of from 20C. to 250C. when pressures are employed that are hi~h enough to keep the ., reactants and reaction products in the li~uid phase throughout the reaction. There is, however, no disclosure either in the description or in the examples o~ the patent which show that high yields of alkanolamines of any ty~e are obtained when the process ~Z~
is carried out either adiabatically or isothermally without the use of cation exchange resin catalysts, and patentees state tnat without a cation exchange catalyst it is not possiDle to realize an adiabatic reaction because it is too slow. Further, in U.S. Patent No.
3,723,530 to Goetze et al., there is also disclosed a process for preparing a mixture of alkanolamines by the li~uid phase reaction of ethylene oxide ana a iarge excess of ammonia, that is mole ratios of ammonia to ethylene oxide of from L~ to ~0 to one. The patent teaches that when the reaction is carried out in the presence of up to 1 mole of dietnanolamine per mole of ethylene oxide, the product obtained will be a mixture of only monoethanolamine and triethanolamine witn little or no diethanolamine being present. The process of the invention is described as being capaole of being run continuously, either isothermally or adiabatically.
When operated continuously, the reaction is carried out in the liquid phase at temperatures in the range of from 60 to 150C and pressures of from 20 to 120 atmospheres, and the monoethanolamine content of the product mixture yenerally does not exceed 7Q percent by weight. A continuous embodiment of the process which is descrlbed as being preferred is directed to initially reacting ethylene oxide with an excess of ammonia in a li~uid phase to ~repare a mixture of alkanolamines from which diethanolamine is separated and recycled. The recycled dietnanolamine, when added to fre~h ammonia an~
ethylene oxide starting reactan~s i Q the proportions describ~d, results in t~e net formation of reduced ~Z~
amounts of die~hanolamine. This proce3s, how~ver, re~uires the coneinuous se~aration of dietnanolamine from the product mix~ure and is operated in the liquid phase .
In Canadian patent application S.N. 408,545-1, filed July 30, 1982, ~here is disclosed a process for preparing alkanolamines with high yield~ of monoalkanolamines by reacting ~lkylene oxide with a large ~xcess of ammonia in a single supercritical fluid phase. The process disclosed therein is described as being capable o running batcnwise or continuously under isothermsl or adiabatic condi~ions. When the process is run continuously, a reactor which is capable of operating as efficiently as possibl@ as a "plug-flow~
reactor may ~e employe~ for carryin~ out the reaction.
The present invention is dir~cted to preferrea e~bo~im~n~s of the continuously run processes described in said copending application.
SU~ARY OF T~E I~V~NTION
.
In accordance with the present invention, there is ~rovi~ed a continuous p~oces~ for preparing alkanolamines with high yields of monoalkanolamine which comprises continuously reacting a flo~ing stream of a homogeneou~ mixture o~ an alkylene oxide having from two to four c~rbon atoms ana ammonia in a molar ratio o~
ammonia to alkylene oxide within ~he range from about 15:1 to about 50:1 maintained in a ~ingle supercritical fluid pha~e in a plug-flow reac~or at ~emperatures at which the reaction proceeds above about 100C. ana at .~
pressures high enough to maintain the reaction mixture in a single supercritical fluid phase having a density at least about 15 lbs/cu.ft. (240 kg/cu.m.) for the time necessary to form an alkanolamine proauct mixture containing predominately monoalkanolamine. Unreacted ammonia may be separated from the pro~ucc mixture and recycled while the alkanolamine product mixture is recovered, or the prcduct mixture may be used in the preparation of further amine products, if desired.
The temperatures employed for carrying out the reaction are preferably as high as possible so that the reaction will proceed at a suitable rate and temperatures above the critical temperature of the reaction mixture may be advantageously used. The pressure should be high enough to maintain the reaction mixture in a single nomogeneous pnase as a supercritical fluid at any point during the reaction. The density of the supercritical fluid reac~ion mixture is an important consideration as to the rate at which the reaction proceeds and should be maintained as hign a possible throughout the reaction and generally at least about 15 lbs./cu. ft. 12~0 kg/cu.m.). Tbe reaction can be carried out under isothermal or, preferably adiabatic conditions and, while no cata~yst is required, tne presence of a small amount of water in the reaction mixture ha~ an advantayeous catalytic effect. The term "supercritical fluid" as used herein is defined as the physical state oE tne reaction mixture wherein eitner the pressure or both the temperature and pressure conditions are above tne critical vaLues therefor. The term "plug-flow reactor" as used herein is defined as a reactor in which there is no mixing of a stream of fluids in the direction of the flow thereof through the reactor. Such plug-flow reactors may oe non-adiaoatic tubular or adiabatic pipe.
DESCRIPTION OF T~ INVENTIO~
. . . ~ _ .
The process of the invention comprises continuously reacting a homogeneous flowing stream of a mixture of alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 which is maintained in a single, nomogeneous phase as a supercritical fluid at temperatures at which the reaction proceeds a~ove aDout 100C. and at pressures high enough to maintain the reaction mixture in a supercritical fluid phase having a ~ensity of at least 15 lbs/cu~ft. for the time necessary to form a product mixture composed predominately of monoalkanolamine (generally about 75%) and small amounts of di-and trialkanolamine. If desired, unreacted a~nonia can be separated from said product mixture at the completion of the reaction with alkylene oxide and recycle~ while tne alkanolamine product mixture is recovered. The mono-, -di-, and trial~anolamines can also be separatea, if de~ired. The pro~uct mixture, including unreacted ammonia, may also ~e used in the preparation of other amine product~.
~ he alkylene oxides to which the process of the present invention is applicable is any alkylene oxide ~2~
131~0 having from two to four carbon atoms, including ethylene oxide, propylene oxide, l,2-butylene oxide, 2,3-butylen~
oxide, and isobutylene oxide.
In accordance with the present invention, it is essential that a large excess of ammonia relative to the alkylene oxide is used in tne reaction ~o obtain yields of monoalkanolamines of at least 65 weight percent. It is advantageous to use from about 15 to about 50 moles, and preferably from about 20 to about 35 moles, of ammonia for each mole of alkylene oxide to obtain yields of monoalkanolamine in many cases of from about 70 to 85 weight percent.
It is essential that the reac~ion of alkyLene oxide and ammonia be carried out in a homogeneous, single supercri~ical fluid phase so tnat tne reaction will proceed at a suitable rate. The reaction can be carried out under isothermal or, preferably, adiabatic conditions. The temperature at which the reaction should be carried out i5 within the range from a~out 100C. to about 200C., though the upper limit of the temperature is not critical. Pre~erably, the reaction tempera~ure is within the range from about the critical temperature o~ tne reaction mixture (generally from about 130C.) to about 180C. Under isothermal conditions, since tne reaction is strongly exotner;nic, it is necessary to withdraw heat from the reaction MixtUre ~o keep the temperature approximately constant.
In the case when the reaction is to be carried out under adiaDatic or nearly adiabatic conditions, the reactants are preheated, preferably to a temperature in
is carried out either adiabatically or isothermally without the use of cation exchange resin catalysts, and patentees state tnat without a cation exchange catalyst it is not possiDle to realize an adiabatic reaction because it is too slow. Further, in U.S. Patent No.
3,723,530 to Goetze et al., there is also disclosed a process for preparing a mixture of alkanolamines by the li~uid phase reaction of ethylene oxide ana a iarge excess of ammonia, that is mole ratios of ammonia to ethylene oxide of from L~ to ~0 to one. The patent teaches that when the reaction is carried out in the presence of up to 1 mole of dietnanolamine per mole of ethylene oxide, the product obtained will be a mixture of only monoethanolamine and triethanolamine witn little or no diethanolamine being present. The process of the invention is described as being capaole of being run continuously, either isothermally or adiabatically.
When operated continuously, the reaction is carried out in the liquid phase at temperatures in the range of from 60 to 150C and pressures of from 20 to 120 atmospheres, and the monoethanolamine content of the product mixture yenerally does not exceed 7Q percent by weight. A continuous embodiment of the process which is descrlbed as being preferred is directed to initially reacting ethylene oxide with an excess of ammonia in a li~uid phase to ~repare a mixture of alkanolamines from which diethanolamine is separated and recycled. The recycled dietnanolamine, when added to fre~h ammonia an~
ethylene oxide starting reactan~s i Q the proportions describ~d, results in t~e net formation of reduced ~Z~
amounts of die~hanolamine. This proce3s, how~ver, re~uires the coneinuous se~aration of dietnanolamine from the product mix~ure and is operated in the liquid phase .
In Canadian patent application S.N. 408,545-1, filed July 30, 1982, ~here is disclosed a process for preparing alkanolamines with high yield~ of monoalkanolamines by reacting ~lkylene oxide with a large ~xcess of ammonia in a single supercritical fluid phase. The process disclosed therein is described as being capable o running batcnwise or continuously under isothermsl or adiabatic condi~ions. When the process is run continuously, a reactor which is capable of operating as efficiently as possibl@ as a "plug-flow~
reactor may ~e employe~ for carryin~ out the reaction.
The present invention is dir~cted to preferrea e~bo~im~n~s of the continuously run processes described in said copending application.
SU~ARY OF T~E I~V~NTION
.
In accordance with the present invention, there is ~rovi~ed a continuous p~oces~ for preparing alkanolamines with high yields of monoalkanolamine which comprises continuously reacting a flo~ing stream of a homogeneou~ mixture o~ an alkylene oxide having from two to four c~rbon atoms ana ammonia in a molar ratio o~
ammonia to alkylene oxide within ~he range from about 15:1 to about 50:1 maintained in a ~ingle supercritical fluid pha~e in a plug-flow reac~or at ~emperatures at which the reaction proceeds above about 100C. ana at .~
pressures high enough to maintain the reaction mixture in a single supercritical fluid phase having a density at least about 15 lbs/cu.ft. (240 kg/cu.m.) for the time necessary to form an alkanolamine proauct mixture containing predominately monoalkanolamine. Unreacted ammonia may be separated from the pro~ucc mixture and recycled while the alkanolamine product mixture is recovered, or the prcduct mixture may be used in the preparation of further amine products, if desired.
The temperatures employed for carrying out the reaction are preferably as high as possible so that the reaction will proceed at a suitable rate and temperatures above the critical temperature of the reaction mixture may be advantageously used. The pressure should be high enough to maintain the reaction mixture in a single nomogeneous pnase as a supercritical fluid at any point during the reaction. The density of the supercritical fluid reac~ion mixture is an important consideration as to the rate at which the reaction proceeds and should be maintained as hign a possible throughout the reaction and generally at least about 15 lbs./cu. ft. 12~0 kg/cu.m.). Tbe reaction can be carried out under isothermal or, preferably adiabatic conditions and, while no cata~yst is required, tne presence of a small amount of water in the reaction mixture ha~ an advantayeous catalytic effect. The term "supercritical fluid" as used herein is defined as the physical state oE tne reaction mixture wherein eitner the pressure or both the temperature and pressure conditions are above tne critical vaLues therefor. The term "plug-flow reactor" as used herein is defined as a reactor in which there is no mixing of a stream of fluids in the direction of the flow thereof through the reactor. Such plug-flow reactors may oe non-adiaoatic tubular or adiabatic pipe.
DESCRIPTION OF T~ INVENTIO~
. . . ~ _ .
The process of the invention comprises continuously reacting a homogeneous flowing stream of a mixture of alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 which is maintained in a single, nomogeneous phase as a supercritical fluid at temperatures at which the reaction proceeds a~ove aDout 100C. and at pressures high enough to maintain the reaction mixture in a supercritical fluid phase having a ~ensity of at least 15 lbs/cu~ft. for the time necessary to form a product mixture composed predominately of monoalkanolamine (generally about 75%) and small amounts of di-and trialkanolamine. If desired, unreacted a~nonia can be separated from said product mixture at the completion of the reaction with alkylene oxide and recycle~ while tne alkanolamine product mixture is recovered. The mono-, -di-, and trial~anolamines can also be separatea, if de~ired. The pro~uct mixture, including unreacted ammonia, may also ~e used in the preparation of other amine product~.
~ he alkylene oxides to which the process of the present invention is applicable is any alkylene oxide ~2~
131~0 having from two to four carbon atoms, including ethylene oxide, propylene oxide, l,2-butylene oxide, 2,3-butylen~
oxide, and isobutylene oxide.
In accordance with the present invention, it is essential that a large excess of ammonia relative to the alkylene oxide is used in tne reaction ~o obtain yields of monoalkanolamines of at least 65 weight percent. It is advantageous to use from about 15 to about 50 moles, and preferably from about 20 to about 35 moles, of ammonia for each mole of alkylene oxide to obtain yields of monoalkanolamine in many cases of from about 70 to 85 weight percent.
It is essential that the reac~ion of alkyLene oxide and ammonia be carried out in a homogeneous, single supercri~ical fluid phase so tnat tne reaction will proceed at a suitable rate. The reaction can be carried out under isothermal or, preferably, adiabatic conditions. The temperature at which the reaction should be carried out i5 within the range from a~out 100C. to about 200C., though the upper limit of the temperature is not critical. Pre~erably, the reaction tempera~ure is within the range from about the critical temperature o~ tne reaction mixture (generally from about 130C.) to about 180C. Under isothermal conditions, since tne reaction is strongly exotner;nic, it is necessary to withdraw heat from the reaction MixtUre ~o keep the temperature approximately constant.
In the case when the reaction is to be carried out under adiaDatic or nearly adiabatic conditions, the reactants are preheated, preferably to a temperature in
4~
131~0 the range from about 100C. to about 160C.j before the~
are introduced into ~he reactor. Because of the reaction heat involved, any selected initial reaction temperature rapidly increases and the initial reaction temperatures should be chosen so that the maximum desired temperature will be obtained during the period of residence of the reaction mixture within the reactor. The preferred maximum temperature is between about 170C. and 180C., though the higher the reaction temperature, the hiyher the pressure that is necessary to maintain the density of the reaction mixture as high as possible.
At sucn reaction temperatures, it is essential that the pressures imposed on the system are high enough ~o maintain tne reaction mixture in a single supercritical fluid phase. In any case, the reaction pressure shouia be at least as nigh as tne criticai pressure of the reaction mixture at any poin~
encountered during the process. Preferably, tne pressures imposed on the system are within the range from about 170 to about 240 atmospheres. TAe latter is a practical upper limit and is not critical.
As pointed out hereinabove, it is important that the reaction mixture is maintained in a single homogeneous phase as a supercritical ~luld and that the density thereof is as high as possible so that the reaction will proceed at a suitable rate. Tne density of the reaction mixture should be above its critical density and, in general, at least 15 1DS/CU. ft. ~240 kg/cu.m~). Preferably, the density of the reaction _ g _ ~ Z ~ 13150 mixture should be maintained in the range of from about 21 to about 28 lbs/cu. ft. or even higher, if practical. The mole ratio of the ammonia and alkylene oxide reactants and the reaction temperature have a significant effect on the density of the reaction mixture. It is important, therefore, that the reaction pressures are maintained as high as is practical so that tne reaction mixture is not only maintained in a single supercritical fluid phase but that the density of said mixture is as high as possible.
While it is not essential that the process of the invention be carried out in the presence of any catalyst, advantageous embodiments of the process of the invention may be carried out with a small amount of water incorp~rated in the reaction mixture along with the alkylene oxide and a~nonia reactants. It has been found that the presence of small amounts of water in the reaction mixture has an advantageous catalytic effect on the reaction rate for forming alkanolamines though it does not appear to affect the yield of monoalkanolamine in the product mixture. The amount of water that is present is not critical, and onLy small amounts of water will achieve the catalytic affect ~hat may be desired.
In general, from about 0.5 percent to about 5 percent by weight of water based on the weight of the reaction mixture may be present. Amounts of water greatly in excess of that which may be catalytically useful, ho~ever, should be avoided to limit the energy requirements needed to separate water from the product mixture.
1315~
In accordance with the present invention the process may be carried out continuously under isothermal or, preferably, adiabatic conditions in a plug-flow reactor or series of reactors which have a small cross-section in comparison to their length. A
turbulent plug-flow reactor allows for tne unidirectional flow of a process stream of reactants that minimizes back-mixing (axial mixing) within the reactor. The reactor may be provided with heat exchange means to maintain the temperatura of the flowing reaction mixture at desired levels but such temperature control means would not be needed if the reaction is carried out under adiabatic conditions.
In the continuous reaction process of the invention, a liquid mixture of the ammonia and alkylene oxide reactants in the molar ratios hereinabove described, preferably with a small amount of water admixed therewith, is preheated and then fed to the reactor through an inlet section therein where a swirling motion is imposed on the feed stream. When a tubular reactor (non-adiabatic) i5 employed, the reaction may be controlled to proceed within a relatively narrow temperature range such as, for example, about 20C. though the temperature of tne feed mixture may be varied over a wide temperature range, such as, for example, from about 20 to about 100C.
Under adiabatic conditions, the mixture of reactants should be preheated to a temperature, from between about 100C to about 1~0C, so that the maximum desired reaction temperature (generally from about 170 to 200) ~,z~
will be attained during the period of residence of the reaction mixture wi~nin the reactor or series of rea~tors. The pressure within the reac~or shall be high enough so that the reaction mixture is maintained in a single, homogeneous phase as a supercritical fluid having the highest possible density at any point within the reactor.
The throughput rate of tne reaction mixture should be chosen to provide a residence ~ime within the reactor or reaccors sufficient to permit the reaction to proceed to completion, generally less than about 1/2 hour. In an adiabatic reactor having the inlet feed configuration herein described, a velocity of from about 0.15 to about 0.5 feet/second or even nigher of the fluid stream may be advantageously employed to permit plug-flow operation. At the completion of the reaction, that is generally when all the alkylene oxide has b~en reacted, the unreacted ammonia can be separated from the product mixture by means known in the art, such as by reducing the pressure on the product mixture to below that at which the ammonia is in a gaseous phase or by distilling under pressure, and the alkanolamine proauct mixture may be recovered. The unreacted, separated ammonia can then be recycled, if ~esired, by repressurizing or condensing to a liquid state prior to mixing with ~re~A alkylene oxide. The alkanolamlne analogues in the product mixture may also be separated by known distillation methods. Tne product mixture obtained during the continuous reaction process may also be used without further treatment as a starting material for the preparation of other organic amines.
The present invention will be further described with reference to the accompanying drawing in which:
Fig. l is a schematic showing of a typical adiabatic reaction system for use in the invention.
Fig. 2 is a schematic illustration of an adiabatic plug flow reactor suitable for use in the invention.
Referring to Fig. l of the drawing, li~uid ammonia and alkylene oxide are blended in the proportions herein described in the feed pipe 1. Small amounts of water may also be added, if desired. The mixture of reactants is pumped througn line 2 to a preheater 3 where the mixture is heated to a temperature in the range from about 100C to about 160C and tnen fed through an axial inlet pipe 4 to the adiabatic reactor. The adiabatic reactor may be a single plug-flow reac~or or, as shown, a series of plug-flow reactor stages 5a, 5b, and 5c, each of which has an 20~ axial inlet pipe. Means are provided for imposing a swirling motion on the reaction mixture feed stream entering each reactor stage to mïnimize thermal stratification therein witnout increasing axial-mixing.
The pressure within each of the reactor stage is maintained in the range, in general, from about 170 to 240 atm by a pressure control valve 6 so that the reaction mixture stream is in a single supercritical fluid phase at any point within the reactor and has a density of at least 15 l~/cu. ft..
The number of reactor stages employed may vary depending on the amount of product to be produced, the total length of reactor re~uired to achieve the desired production rate, the feasible length for any reactor stage, and similar considerations. A typical system may comprise from 1 to 6 reactor stages of up to 100 feet or more in length with 3 to 5 reactor stages being generally advantageously employed.
The product mixture in which all or substantially all of the alkylene oxide has been converted to alkanoiamines is fed from tne last adiabatic reactor stage 5c through pressure control valve 6 and line 10, where the proauct mixture stream is depressurized to between about atmospheric pressure and 40 a~m, and then fed immediately into a flasn separator 11. In the flash separator 11 a substantial amount of tbe unreacted ammonia rapidly separates from the product mixture as a gas which escapes at ~he top of the separator 11 in gaseous form and is recycled via line 12 through a compressor or condensor 13. The alkanolamine product mixture is drawn from the bottom of tAe separator 11 through line 1~ for refining, if desired.
Fig. 2 illustrates an adiabatic reactor 5 typical of the reactor stages 5a, 5b, or Sc of Fig. 1 having an axial inlet pipe 4 into a generally cylindrical hollow body 7 having a small cross-section in comparison to its length which def~nes an internal, longitudinally extending passageway. Mounted within the inlet end 20 thereof are a pair of opposed, semi-elliptically shaped baffles 21 which impose a swirling motion to the reaction mixture fed therethrough to - ~2~4~
achieve a swirling plug-flow regime for the reactor.
~ntermediate the inlet pipe 4 and the opposed baffles 21 in the inlet end 20 of said reactor 5 is mounted a perforated plate 8 which serve to distribute and straighten the flow of fluid entering the cylindrical body 7 of said reactor 5. The semi-elliptically snape~
baffles 21 which impose a swirling motion to the flowing stream of fluid wit~in the reactor Inay be prepared from semi-elliptic plates having ratios of major to minor axis of from about 1.25:1 ~o about 2.0:1. Other means for imposing a swirling ~otion to the flow of fluid tnrough the reactor may also be used such as, for example, baffles with varying configurations, spacing, numbers, size, and metnod of mounting within the inlet end of the reactor, the cross-section and length of the reactor, the velocity of flow t'nrough tne reactor and the like being factors which must be considered in choosing the particular configuration desired.
In a typical embodiment of the processs of the invention, liquid ethylene oxide and a,nmonia in a molar ratio of ammonia to ethylene oxide of 30:1 are blended in feed pipe 1 along with 3 percent by weight of water.
The mixture of reactants is pumped through line 2 to a preheater 3 where the mixture is heated to a temperature of about 130~C. and then fed to adiabatic plug-flow reactor stage 5a, a reactor having an outer diameter of 30 inches and a length of 100 feet at a velocity of 0.3 ft./séc. The reaction mixture is subsequently fed at such velocity to 3 successive adiabatic plug-flow reactor ~tages of similar dimensions and inlet configuration. The pressure in the reactor stages is controlled by pressure control valve 6, hign enough to maintain the reactant mixtures in a single, homogenous phase as a supercritical fluid naving a density of 2~
lbs./cu.ft. at any point therein, generally about 200 to 210 atmospheres. After a total residence time in the reactor of about 25 to 30 minutes, the product mixture exits from the last reactor stage at a temperature o~
about 175C. and is fed through pressure control valve 6 and line lO to flash separator ll. The product mixture passing through line lO is depressurized to about 20 atmospheres an~ when the product Inixture enters the flash separator ll, unreacted ammonia is rapidly separated tnerefrom and exits fro~ the top of the separator through line 12. The unreacted ammonia is then condensed to a li~uid in condenser 12 and recycled.
The alkanolamine product mixture is fed from tne bottom of separator ll through line L4, rerined by known distillation techniques and recovered.
This invention will become more clear when considered together with the following examples which are se~ forth as being merely iLlustrative of tne invention and which are not intended in any manner, to be limitative tnereof. Unless otherwise indicated, all parts and percentages are by weight.
s EX~MPLE 1 A reaction system ana apparatus similar to that shown in the drawlng (Fig. 1 and Fig. 2) except that the adiabatic plug-flow reactor is comprised of 4 reactor stages, each of which are 30 inches in diameter and lO0 feet long, was used in a continuous run in which ethylene oxide was reacted with ammonia. In this run a liquid ethylene oxide feed of 5000 pounas per hour was mixed with a liquid ammonia-water mixture feed of 90,000 pounds per nour (96 percent NH3, 4 percent water) to give an ammonia to ethylene oxide mole ratio of 45:1.
The mixed ammonia an~ ethylene oxide feed was preheated to a temperature of about 150C. and then pumped into the rirst reactor stage at a velocity of about 0.21 feet/sec. The pressure in the reactor stages was controlled to maintain the flowing stream in a single supercritical fluid phase having an average reaction mixture density of about 21.5 lbs./cu.ft. The pressure at the outlet of the final reactor stage was about 2700 psig (about 184 atm.) and the temperature vf tne praduct mixture at the outlet of the fourth reactor stage was about 170C. after a residence time witnin the reactor stages of 28 min~tes. The product mixture from the final reactor stage was depressurized to about 400 psig (27 atm.) in the line leading to a flash-tank separator and substantiallySall the unreacted ammonia separated from the product mixture in ~he flash-tank separator.
The separated ammoniat-COMMAND-)001 from the top of the separator and passed through a condenser where it was condensed to a li~uid and then was recycled.
The product mixture was recovered from the bottom of the flash-tank separator, refined to remove the small amount of unreacted ammonia that was entrained therewitn, and then collected. The composition of the product mixture was determined by gas chromatographic analysis to contain 80 percent by ~eight of monoethanolamine, 17.5 percent by weight of diethanolamine, and 2.5 percent by weight of triethanolamine. No measurable amount of unreacted ethylene oxide was found.
Using the reaction systeJQ and apparatus of Example 1, a continous run was made in which a liquid ethylene oxide feed of 5200 pounas per hour was mixed with a liquid ammonia-water mixture feed of ~0,000 pounds per nour (97 percent NH3 and 3 percent water) to give an ammonia ~o ethylene oxide mole ratio of 44:1. Tne mixed ammonia and ethylene oxide feed was preheated to a temperature of about 154Co and pumped into the first reactor stage at a velocity of about 0.26 ft./sec. The pressure in the reactor stages was controlled to maintain tne flowing stream o~ reactants in a single supercritical fluid phase having an average reaction mixture density of about 22.5 lbs./cu.ft. The pressure at the outlet of the final reactor stage was about 3000 psig (204 atms.) and the temperature of tne product mixture at the outlet of the final reactor stage was about 174.5C. a~ter a residence time of 2g minutes.
The temperature of the reaction mixture at the outlet of eacA of the reactor stages was found to be:
at the outlet of the first reactor stage - 166C.
at the outlet of the second reactor stage - 169.6C.
at the outlet of the third reactor stage - 174.8C.
The product mixture from the final rea~tor stage was depressurized to about 400 p5i9 and fed to a flash-tank separator wAere substantially all the unreacted ammonia rapidly separated from the product mixture and was then taken from the top of the separator, condensed to a liquid and recycled.
The product mixture recovered rrom the bo~tom of the separator was collected and determined to have the following composition:
83 percent by weight monoethanolamine 15 percent by weight diethanolamine 2 percent by weight triethanolamine No measurable amount of unreacted ethylene oxide was found in the product mixture.
Using the reaction system and apparatus of Example 1, a continous run was made in whic~ a liquid ethylene oxide feed of 10,000 pounds per hour was mixed with a liquid ammonia-water mixture feed of 11~,000 pounds per hour (97.5 percent NH3, 2.5 percent water) to give an ammonia to ethylene mole ratio of 29:1. The reactant mixture was preheated to a temperature of a~out 150C. and pumpPd into the first reactor stage at a velocity of 0.33 ft./sec. The pressure in tne reactor 4~
stages was controlled to maintain the reactant mixture in a single supercritical fluid pnase having an average rea~tion mixture density of about 23 lbs./cu.ft.
The pressure at the outlet of tAe final reactor was about 3,000 psig (204 atms.) and the temperature of the product mixture at the outlet of the final reactor stage was about 180C. after a residence time of 23 minutes.
Analysis of tne product mixture after scparating unreacted ammonia was determined to be:
76.2 percent by weight of monoethanolamine 20.8 percent by weight of diethanolamine 3.0 percent by weight of ~riethanolamine It was also determined tAat 0.1 percent unreacted ethylene oxide was present in the produc~
mixture.
131~0 the range from about 100C. to about 160C.j before the~
are introduced into ~he reactor. Because of the reaction heat involved, any selected initial reaction temperature rapidly increases and the initial reaction temperatures should be chosen so that the maximum desired temperature will be obtained during the period of residence of the reaction mixture within the reactor. The preferred maximum temperature is between about 170C. and 180C., though the higher the reaction temperature, the hiyher the pressure that is necessary to maintain the density of the reaction mixture as high as possible.
At sucn reaction temperatures, it is essential that the pressures imposed on the system are high enough ~o maintain tne reaction mixture in a single supercritical fluid phase. In any case, the reaction pressure shouia be at least as nigh as tne criticai pressure of the reaction mixture at any poin~
encountered during the process. Preferably, tne pressures imposed on the system are within the range from about 170 to about 240 atmospheres. TAe latter is a practical upper limit and is not critical.
As pointed out hereinabove, it is important that the reaction mixture is maintained in a single homogeneous phase as a supercritical ~luld and that the density thereof is as high as possible so that the reaction will proceed at a suitable rate. Tne density of the reaction mixture should be above its critical density and, in general, at least 15 1DS/CU. ft. ~240 kg/cu.m~). Preferably, the density of the reaction _ g _ ~ Z ~ 13150 mixture should be maintained in the range of from about 21 to about 28 lbs/cu. ft. or even higher, if practical. The mole ratio of the ammonia and alkylene oxide reactants and the reaction temperature have a significant effect on the density of the reaction mixture. It is important, therefore, that the reaction pressures are maintained as high as is practical so that tne reaction mixture is not only maintained in a single supercritical fluid phase but that the density of said mixture is as high as possible.
While it is not essential that the process of the invention be carried out in the presence of any catalyst, advantageous embodiments of the process of the invention may be carried out with a small amount of water incorp~rated in the reaction mixture along with the alkylene oxide and a~nonia reactants. It has been found that the presence of small amounts of water in the reaction mixture has an advantageous catalytic effect on the reaction rate for forming alkanolamines though it does not appear to affect the yield of monoalkanolamine in the product mixture. The amount of water that is present is not critical, and onLy small amounts of water will achieve the catalytic affect ~hat may be desired.
In general, from about 0.5 percent to about 5 percent by weight of water based on the weight of the reaction mixture may be present. Amounts of water greatly in excess of that which may be catalytically useful, ho~ever, should be avoided to limit the energy requirements needed to separate water from the product mixture.
1315~
In accordance with the present invention the process may be carried out continuously under isothermal or, preferably, adiabatic conditions in a plug-flow reactor or series of reactors which have a small cross-section in comparison to their length. A
turbulent plug-flow reactor allows for tne unidirectional flow of a process stream of reactants that minimizes back-mixing (axial mixing) within the reactor. The reactor may be provided with heat exchange means to maintain the temperatura of the flowing reaction mixture at desired levels but such temperature control means would not be needed if the reaction is carried out under adiabatic conditions.
In the continuous reaction process of the invention, a liquid mixture of the ammonia and alkylene oxide reactants in the molar ratios hereinabove described, preferably with a small amount of water admixed therewith, is preheated and then fed to the reactor through an inlet section therein where a swirling motion is imposed on the feed stream. When a tubular reactor (non-adiabatic) i5 employed, the reaction may be controlled to proceed within a relatively narrow temperature range such as, for example, about 20C. though the temperature of tne feed mixture may be varied over a wide temperature range, such as, for example, from about 20 to about 100C.
Under adiabatic conditions, the mixture of reactants should be preheated to a temperature, from between about 100C to about 1~0C, so that the maximum desired reaction temperature (generally from about 170 to 200) ~,z~
will be attained during the period of residence of the reaction mixture wi~nin the reactor or series of rea~tors. The pressure within the reac~or shall be high enough so that the reaction mixture is maintained in a single, homogeneous phase as a supercritical fluid having the highest possible density at any point within the reactor.
The throughput rate of tne reaction mixture should be chosen to provide a residence ~ime within the reactor or reaccors sufficient to permit the reaction to proceed to completion, generally less than about 1/2 hour. In an adiabatic reactor having the inlet feed configuration herein described, a velocity of from about 0.15 to about 0.5 feet/second or even nigher of the fluid stream may be advantageously employed to permit plug-flow operation. At the completion of the reaction, that is generally when all the alkylene oxide has b~en reacted, the unreacted ammonia can be separated from the product mixture by means known in the art, such as by reducing the pressure on the product mixture to below that at which the ammonia is in a gaseous phase or by distilling under pressure, and the alkanolamine proauct mixture may be recovered. The unreacted, separated ammonia can then be recycled, if ~esired, by repressurizing or condensing to a liquid state prior to mixing with ~re~A alkylene oxide. The alkanolamlne analogues in the product mixture may also be separated by known distillation methods. Tne product mixture obtained during the continuous reaction process may also be used without further treatment as a starting material for the preparation of other organic amines.
The present invention will be further described with reference to the accompanying drawing in which:
Fig. l is a schematic showing of a typical adiabatic reaction system for use in the invention.
Fig. 2 is a schematic illustration of an adiabatic plug flow reactor suitable for use in the invention.
Referring to Fig. l of the drawing, li~uid ammonia and alkylene oxide are blended in the proportions herein described in the feed pipe 1. Small amounts of water may also be added, if desired. The mixture of reactants is pumped througn line 2 to a preheater 3 where the mixture is heated to a temperature in the range from about 100C to about 160C and tnen fed through an axial inlet pipe 4 to the adiabatic reactor. The adiabatic reactor may be a single plug-flow reac~or or, as shown, a series of plug-flow reactor stages 5a, 5b, and 5c, each of which has an 20~ axial inlet pipe. Means are provided for imposing a swirling motion on the reaction mixture feed stream entering each reactor stage to mïnimize thermal stratification therein witnout increasing axial-mixing.
The pressure within each of the reactor stage is maintained in the range, in general, from about 170 to 240 atm by a pressure control valve 6 so that the reaction mixture stream is in a single supercritical fluid phase at any point within the reactor and has a density of at least 15 l~/cu. ft..
The number of reactor stages employed may vary depending on the amount of product to be produced, the total length of reactor re~uired to achieve the desired production rate, the feasible length for any reactor stage, and similar considerations. A typical system may comprise from 1 to 6 reactor stages of up to 100 feet or more in length with 3 to 5 reactor stages being generally advantageously employed.
The product mixture in which all or substantially all of the alkylene oxide has been converted to alkanoiamines is fed from tne last adiabatic reactor stage 5c through pressure control valve 6 and line 10, where the proauct mixture stream is depressurized to between about atmospheric pressure and 40 a~m, and then fed immediately into a flasn separator 11. In the flash separator 11 a substantial amount of tbe unreacted ammonia rapidly separates from the product mixture as a gas which escapes at ~he top of the separator 11 in gaseous form and is recycled via line 12 through a compressor or condensor 13. The alkanolamine product mixture is drawn from the bottom of tAe separator 11 through line 1~ for refining, if desired.
Fig. 2 illustrates an adiabatic reactor 5 typical of the reactor stages 5a, 5b, or Sc of Fig. 1 having an axial inlet pipe 4 into a generally cylindrical hollow body 7 having a small cross-section in comparison to its length which def~nes an internal, longitudinally extending passageway. Mounted within the inlet end 20 thereof are a pair of opposed, semi-elliptically shaped baffles 21 which impose a swirling motion to the reaction mixture fed therethrough to - ~2~4~
achieve a swirling plug-flow regime for the reactor.
~ntermediate the inlet pipe 4 and the opposed baffles 21 in the inlet end 20 of said reactor 5 is mounted a perforated plate 8 which serve to distribute and straighten the flow of fluid entering the cylindrical body 7 of said reactor 5. The semi-elliptically snape~
baffles 21 which impose a swirling motion to the flowing stream of fluid wit~in the reactor Inay be prepared from semi-elliptic plates having ratios of major to minor axis of from about 1.25:1 ~o about 2.0:1. Other means for imposing a swirling ~otion to the flow of fluid tnrough the reactor may also be used such as, for example, baffles with varying configurations, spacing, numbers, size, and metnod of mounting within the inlet end of the reactor, the cross-section and length of the reactor, the velocity of flow t'nrough tne reactor and the like being factors which must be considered in choosing the particular configuration desired.
In a typical embodiment of the processs of the invention, liquid ethylene oxide and a,nmonia in a molar ratio of ammonia to ethylene oxide of 30:1 are blended in feed pipe 1 along with 3 percent by weight of water.
The mixture of reactants is pumped through line 2 to a preheater 3 where the mixture is heated to a temperature of about 130~C. and then fed to adiabatic plug-flow reactor stage 5a, a reactor having an outer diameter of 30 inches and a length of 100 feet at a velocity of 0.3 ft./séc. The reaction mixture is subsequently fed at such velocity to 3 successive adiabatic plug-flow reactor ~tages of similar dimensions and inlet configuration. The pressure in the reactor stages is controlled by pressure control valve 6, hign enough to maintain the reactant mixtures in a single, homogenous phase as a supercritical fluid naving a density of 2~
lbs./cu.ft. at any point therein, generally about 200 to 210 atmospheres. After a total residence time in the reactor of about 25 to 30 minutes, the product mixture exits from the last reactor stage at a temperature o~
about 175C. and is fed through pressure control valve 6 and line lO to flash separator ll. The product mixture passing through line lO is depressurized to about 20 atmospheres an~ when the product Inixture enters the flash separator ll, unreacted ammonia is rapidly separated tnerefrom and exits fro~ the top of the separator through line 12. The unreacted ammonia is then condensed to a li~uid in condenser 12 and recycled.
The alkanolamine product mixture is fed from tne bottom of separator ll through line L4, rerined by known distillation techniques and recovered.
This invention will become more clear when considered together with the following examples which are se~ forth as being merely iLlustrative of tne invention and which are not intended in any manner, to be limitative tnereof. Unless otherwise indicated, all parts and percentages are by weight.
s EX~MPLE 1 A reaction system ana apparatus similar to that shown in the drawlng (Fig. 1 and Fig. 2) except that the adiabatic plug-flow reactor is comprised of 4 reactor stages, each of which are 30 inches in diameter and lO0 feet long, was used in a continuous run in which ethylene oxide was reacted with ammonia. In this run a liquid ethylene oxide feed of 5000 pounas per hour was mixed with a liquid ammonia-water mixture feed of 90,000 pounds per nour (96 percent NH3, 4 percent water) to give an ammonia to ethylene oxide mole ratio of 45:1.
The mixed ammonia an~ ethylene oxide feed was preheated to a temperature of about 150C. and then pumped into the rirst reactor stage at a velocity of about 0.21 feet/sec. The pressure in the reactor stages was controlled to maintain the flowing stream in a single supercritical fluid phase having an average reaction mixture density of about 21.5 lbs./cu.ft. The pressure at the outlet of the final reactor stage was about 2700 psig (about 184 atm.) and the temperature vf tne praduct mixture at the outlet of the fourth reactor stage was about 170C. after a residence time witnin the reactor stages of 28 min~tes. The product mixture from the final reactor stage was depressurized to about 400 psig (27 atm.) in the line leading to a flash-tank separator and substantiallySall the unreacted ammonia separated from the product mixture in ~he flash-tank separator.
The separated ammoniat-COMMAND-)001 from the top of the separator and passed through a condenser where it was condensed to a li~uid and then was recycled.
The product mixture was recovered from the bottom of the flash-tank separator, refined to remove the small amount of unreacted ammonia that was entrained therewitn, and then collected. The composition of the product mixture was determined by gas chromatographic analysis to contain 80 percent by ~eight of monoethanolamine, 17.5 percent by weight of diethanolamine, and 2.5 percent by weight of triethanolamine. No measurable amount of unreacted ethylene oxide was found.
Using the reaction systeJQ and apparatus of Example 1, a continous run was made in which a liquid ethylene oxide feed of 5200 pounas per hour was mixed with a liquid ammonia-water mixture feed of ~0,000 pounds per nour (97 percent NH3 and 3 percent water) to give an ammonia ~o ethylene oxide mole ratio of 44:1. Tne mixed ammonia and ethylene oxide feed was preheated to a temperature of about 154Co and pumped into the first reactor stage at a velocity of about 0.26 ft./sec. The pressure in the reactor stages was controlled to maintain tne flowing stream o~ reactants in a single supercritical fluid phase having an average reaction mixture density of about 22.5 lbs./cu.ft. The pressure at the outlet of the final reactor stage was about 3000 psig (204 atms.) and the temperature of tne product mixture at the outlet of the final reactor stage was about 174.5C. a~ter a residence time of 2g minutes.
The temperature of the reaction mixture at the outlet of eacA of the reactor stages was found to be:
at the outlet of the first reactor stage - 166C.
at the outlet of the second reactor stage - 169.6C.
at the outlet of the third reactor stage - 174.8C.
The product mixture from the final rea~tor stage was depressurized to about 400 p5i9 and fed to a flash-tank separator wAere substantially all the unreacted ammonia rapidly separated from the product mixture and was then taken from the top of the separator, condensed to a liquid and recycled.
The product mixture recovered rrom the bo~tom of the separator was collected and determined to have the following composition:
83 percent by weight monoethanolamine 15 percent by weight diethanolamine 2 percent by weight triethanolamine No measurable amount of unreacted ethylene oxide was found in the product mixture.
Using the reaction system and apparatus of Example 1, a continous run was made in whic~ a liquid ethylene oxide feed of 10,000 pounds per hour was mixed with a liquid ammonia-water mixture feed of 11~,000 pounds per hour (97.5 percent NH3, 2.5 percent water) to give an ammonia to ethylene mole ratio of 29:1. The reactant mixture was preheated to a temperature of a~out 150C. and pumpPd into the first reactor stage at a velocity of 0.33 ft./sec. The pressure in tne reactor 4~
stages was controlled to maintain the reactant mixture in a single supercritical fluid pnase having an average rea~tion mixture density of about 23 lbs./cu.ft.
The pressure at the outlet of tAe final reactor was about 3,000 psig (204 atms.) and the temperature of the product mixture at the outlet of the final reactor stage was about 180C. after a residence time of 23 minutes.
Analysis of tne product mixture after scparating unreacted ammonia was determined to be:
76.2 percent by weight of monoethanolamine 20.8 percent by weight of diethanolamine 3.0 percent by weight of ~riethanolamine It was also determined tAat 0.1 percent unreacted ethylene oxide was present in the produc~
mixture.
Claims (13)
1. A continuous process for preparing alkanol-amines with high yields of monoalkanolamines, which comprises continuously reacting in a plug flow reactor a stream of a homogeneous mixture of an alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 at temperatures above the critical temperature of the mixture and at pressures above the critical pressure of the mixture and maintaining the mixture in a single phase having a density of at least about 15 lbs./cu. ft. for the time necessary to form an alkanolamine product mixture containing at least about 65% by weight monoalkanolamine, said stream flowing in said reactor in a manner that minimizes back-mixing.
2. The process of claim 1 wherein said homogeneous mixture of reactants also contains a small catalytic amount of water.
3. The process of claim 1 wherein a swirling motion is imposed on the stream of reactants flowing through said reactor to avoid thermal stratification.
4. The process of claim 1 wherein unreacted ammonia is separated from the alkanolamine product mixture after completion of the reaction of the alkylene oxide.
5. The process of claim 4 wherein said separated unreacted ammonia is liquified and recycled for reaction with fresh amounts of alkylene oxide.
6. The process of claim 2 wherein a swirling motion is imposed on the stream of reactants flowing through said reactor to avoid thermal stratification.
7. The process of claim 1 wherein the reaction is carried out under adiabatic conditions at a temperature of up to 200°C.
8. The process of claim 2 wherein the reaction is carried out under adiabatic conditions at temperatures of up to about 200°C.
9. The process of claim 6 wherein the reaction is carried out under adiabatic conditions.
10. The process of claim 1 wherein the reaction is carried out at pressures in the range from about 170 atmospheres to about 240 atmospheres.
11. The process of claim 6 wherein the reaction is carried out at pressures in the range from about 170 atmospheres to about 240 atmospheres.
12. The process of claim 9 wherein the reaction is carried out at pressures in the range from about 170 atmospheres to about 240 atmospheres.
13. A continuous process for preparing alkanolamines with high yields of monoalkanolamines which comprises con-tinuously reacting in a plug flow reactor a stream of a homogeneous mixture of an alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 maintained in a single supercritical fluid phase having a density of at least 15 lbs./cu. ft. for the time necessary to form an alkanolamine product mixture containing predominately monoalkanolamine, said stream flowing in said reaction in a manner that minimizes back-mixing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000405478A CA1210411A (en) | 1982-06-18 | 1982-06-18 | Continuous process for preparing alkanolamines |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000405478A CA1210411A (en) | 1982-06-18 | 1982-06-18 | Continuous process for preparing alkanolamines |
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| Publication Number | Publication Date |
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| CA1210411A true CA1210411A (en) | 1986-08-26 |
Family
ID=4123042
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000405478A Expired CA1210411A (en) | 1982-06-18 | 1982-06-18 | Continuous process for preparing alkanolamines |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5334763A (en) * | 1993-04-22 | 1994-08-02 | The Dow Chemical Company | Processes for making ethanolamines |
-
1982
- 1982-06-18 CA CA000405478A patent/CA1210411A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5334763A (en) * | 1993-04-22 | 1994-08-02 | The Dow Chemical Company | Processes for making ethanolamines |
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