ZA200209596B - Process for preparation of aliphatic amines. - Google Patents
Process for preparation of aliphatic amines. Download PDFInfo
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- ZA200209596B ZA200209596B ZA200209596A ZA200209596A ZA200209596B ZA 200209596 B ZA200209596 B ZA 200209596B ZA 200209596 A ZA200209596 A ZA 200209596A ZA 200209596 A ZA200209596 A ZA 200209596A ZA 200209596 B ZA200209596 B ZA 200209596B
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- ZA
- South Africa
- Prior art keywords
- section
- ammonia
- alkene
- pressure
- mixture
- Prior art date
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- 238000000034 method Methods 0.000 title claims description 22
- 238000002360 preparation method Methods 0.000 title claims description 10
- -1 aliphatic amines Chemical class 0.000 title claims description 9
- 230000008569 process Effects 0.000 title claims description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 80
- 150000001336 alkenes Chemical class 0.000 claims description 41
- 229910021529 ammonia Inorganic materials 0.000 claims description 39
- 150000001412 amines Chemical class 0.000 claims description 32
- 238000006243 chemical reaction Methods 0.000 claims description 28
- VQTUBCCKSQIDNK-UHFFFAOYSA-N Isobutene Chemical group CC(C)=C VQTUBCCKSQIDNK-UHFFFAOYSA-N 0.000 claims description 26
- 239000003054 catalyst Substances 0.000 claims description 18
- 230000015572 biosynthetic process Effects 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 12
- 238000003786 synthesis reaction Methods 0.000 claims description 12
- 239000010457 zeolite Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 11
- 239000000376 reactant Substances 0.000 claims description 10
- 238000001816 cooling Methods 0.000 claims description 8
- 229910021536 Zeolite Inorganic materials 0.000 claims description 7
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 7
- 239000011541 reaction mixture Substances 0.000 claims description 7
- 238000000926 separation method Methods 0.000 claims description 7
- 230000001143 conditioned effect Effects 0.000 claims description 5
- 239000002815 homogeneous catalyst Substances 0.000 claims description 5
- 239000008246 gaseous mixture Substances 0.000 claims description 4
- 239000002638 heterogeneous catalyst Substances 0.000 claims description 4
- 238000012856 packing Methods 0.000 claims description 4
- 239000007792 gaseous phase Substances 0.000 claims description 3
- 239000007791 liquid phase Substances 0.000 claims description 3
- 125000004432 carbon atom Chemical group C* 0.000 claims 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N Propene Chemical compound CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 6
- YBRBMKDOPFTVDT-UHFFFAOYSA-N tert-butylamine Chemical compound CC(C)(C)N YBRBMKDOPFTVDT-UHFFFAOYSA-N 0.000 description 6
- 238000005576 amination reaction Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 125000001931 aliphatic group Chemical group 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- HGCIXCUEYOPUTN-UHFFFAOYSA-N cyclohexene Chemical compound C1CCC=CC1 HGCIXCUEYOPUTN-UHFFFAOYSA-N 0.000 description 2
- PAFZNILMFXTMIY-UHFFFAOYSA-N cyclohexylamine Chemical compound NC1CCCCC1 PAFZNILMFXTMIY-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- JJWLVOIRVHMVIS-UHFFFAOYSA-N isopropylamine Chemical compound CC(C)N JJWLVOIRVHMVIS-UHFFFAOYSA-N 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 150000004982 aromatic amines Chemical class 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 150000001728 carbonyl compounds Chemical class 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 150000002505 iron Chemical class 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052680 mordenite Inorganic materials 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 150000002892 organic cations Chemical class 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
Process of preparation of aliphatic amines
Present invention is concerned with a process of preparation of aliphatic = amines by ammonia addition to alkenes.
Most of aliphatic amines are produced by amination of alcohols or possibly by amination of carbonyl compounds. Only currently the addition of ammonia to alkenes starts to be applied according to the scheme .
RCH=CH; + NH3 — RCH-CHs
NH;
The reaction is exothermic, while the equilibrium constant decreases with increasing temperature. Therefore, active catalysts are sought which would provide for sufficient reaction rate also at a temperature of 200 to 250 °C at which the equilibrium conversion of an alkene to an amine is more favourable.
Of course, increasing pressure improves the equilibrium conversion of an alkene to an amine, and most of the current publications and patents give a pressure higher than 2 MPa, and in several cases even 70 MPa.
The reaction rate depends on the catalyst activity, but also on the alkene reactivity. Isobutene is highly reactive, propene reacts more slowly, and ethylene has the smallest activity. While isobutylene reacts with ammonia on a zeolite catalyst quickly enough already at a temperature of 250 °C, ethylene requires a temperature of about 350 °C. ) Many substances have been tried as homogeneous and heterogeneous catalysts for the ammonia addition to alkenes. The greatest attention has been paid to zeolite type catalysts. From US 4 307 250 and US 4 075 002 Y- and X- type zeolites, including various modifications, are known as catalysts which work at the following conditions:
pressure 2.06 to 41.3 MPa temperature 200 to 450 °C molar ratio NHas/alkene 0.2 to 20.
With H-mordenite as a catalyst at a temperature of 300 to 320 °C, a pressure of 5 MPa and a molar ratio NHa/isobutene of 3.95 isobutylene conversion of 15 to 26 % was reached in single experiments, but the conversion selectivity to tert- butylamine was relatively low, reaching 24 to 72 %. In the above mentioned patent documents the side products have not been described, and they are probably oligomers of isobutylene. In EP 0305 564 A1 there is described a partially dealuminized zeolite catalyst which has a higher activity and selectivity, leading to a conversion of 3.8 to 13.6 % at a temperature of 220 to 260 °C, a pressure of 5
MPa and at a molar ratio NHa/isobutylene = 4.
In DE 33 26 579 A1 there is described a method of amine preparation by alkene amination in the presence of a pentasil-type catalyst. An advantage of this catalyst in comparison with the Y-type is higher selectivity and lower formation of carbonaceous deposits, namely at a relatively small excess of ammonia. The pressure of 30 MPa is considered to be optimal, and the highest isobutylene conversion of 12 % has been reached at a temperature of 330 °C, a pressure of 59 MPa and at a molar ratio NHa/isobutylene = 1.5. When aminating isobutylene by the method according to DE 33 27 000 A1 on a boralite-based catalyst at a molar ratio NHs/isobutylene = 1.5, a temperature of 300 °C and a pressure of 30
MPa an isobutylene conversion of 17.3 % has been achieved.
The use of alkali metals and of their hydrides as catalysts for ammonia addition to alkenes is described in US 2 501 556, where pressures of at least 50
MPa and a temperature of 100 to 250 °C are recommended. The use of rare metals of the group VIiI, especially of palladium on a carrier, as catalysis of alkene amination is known from US 3 412 158. The use of homogeneous catalysts, based on the solutions of ruthenium and iron complexes, in preparation of : aliphatic and aromatic amines by ammonia addition to olefines at a temperature of 100 to 250 °C and a pressure of 0.1 to 83 MPa is described in EP 0039 061 B1, but the results of experiments have been evaluated only quantitatively. The use of ammonium halides as catalysts for the above mentioned reaction is known from
EP 0200 923 A2, and that of organic cation exchangers from US 4 536 602.
Nevertheless, only thermostable types based on fluorine compounds are suitable.
It seams that other types of catalysts of ammonia addition to olefins cannot compete with zeolites. Zeolites have excellent thermal stability and they are easily - regenerated with air at a temperature of 400 to 500 °C. Some of the . homogeneous catalysts show corrosive action, whereas zeolites are practically inert.
Most of the patent literature which concerns the amine preparation by zeolite catalyzed addition of ammonia to olefins recommends to perform the above mentioned reaction at a relatively high pressure. For example, in DE 33 26 579 A1 and DE 33 27 000 A1 a pressure in the range of 4 to 70 MPa is considered, but a pressure of 20 to 30 MPa is recommended. Using a lower pressure, for example 5
MPa (US 4 307 250, US 4 375 002, EP 0305 564 A1), the alkene conversion to amine of about 10 % is achieved only with a high excess of ammonia. The reaction mixture is liquefied by cooling, and the unreacted starting substances are separated by rectification. If a higher ammonia excess is used, even more than 10 kg of ammonia, which has high heat of vaporization, per 1 kg of the prepared amine must be evaporated. At a pressure of 30 MPa a similar isobutylene conversion can be achieved also at a molar ratio NHa/isobutylene of 1.5. However, a high-pressure apparatus is very expensive, and injecting the liquids into a high pressure requires much energy for driving the injection pumps.
At present it has been found that it is possible to produce aliphatic amines by the ammonia addition to alkenes using a method according to the present invention which eliminates the high heat consumption of the known procedures.
The nature of the method of preparation of aliphatic amines from ammonia and alkenes in the gas phase using homogeneous or heterogeneous catalysts ’ consists in that the reaction system consists of two sections which are mutually interconnected and conditioned and of one cooling zone which work at a y practically equal pressure of 2 to 8 MPa, while the starting ammonia and alkene enter the first section, where they are mixed with the unreacted ammonia and alkene at the pressure of the synthesis, and the gaseous mixture enters the second section, where a partial chemical transformation of reactants to amine takes place, and the reaction mixture leaving the second section passes the cooling zone and returns to the first section, where the separation of the gaseous » mixture of unreacted ammonia and alkenes from the liquid crude amine takes place, which crude amine is further purified.
N Synthesis of amines from alkenes and ammonia in the system of two mutually conditioned sections working at a practically equal pressure according to the present invention allows that it can be only performed in a relatively narrow range of pressures of 2 to 8 MPa. The term “practically equal pressure” means that the pressure differences in the sections are caused only by the pressure loss in the apparatus and pipes. The upper bound for the working pressure is given by the closeness of the critical pressure of ammonia or of its mixture with an alkene. The function of the first section is namely conditioned by simultaneous existence of the gaseous and liquid phase in it. The critical pressure for ammonia is 11.2 MPa, the critical pressure, for example, for isobutylene is 4.0 MPa.
Only a small part of amines can be separated by a simple partial condensation in the first section at the system pressure. The amine content in the mixture which leaves the second (catalytic) section is namely limited by equilibrium, and it represents only 1 to 3 molar % of the amine. Conversion of alkenes to amine under the conditions according to the invention is 3 to 10 %, and the amine content is further decreased by the excess of ammonia. Therefore, according to the present invention the efficiency of the amine separation from the gaseous mixture is preferably increased by a built-in packing which increases the surface of the interfacial contact of the gas and liquid, while the gas and liquid counterflowly pass the first section. A suitable built-in packing is formed by valve, bubble-cap or sieve trays; orientated or non orientated fillings have small efficiency at a pressure near the critical pressure.
The counterflow of the gas ‘and liquid in the first section can be ensured by . partial condensation of the unreacted part of the starting mixture of alkene and ammonia in the upper part of the first section, possibly also by feeding with fresh liquid reactants at the top of the first section. A suitable separation efficiency, expressed as a number of gas-liquid equilibrium (theoretical) plates, is 10 to 30.
The second section of the reaction system contains any catalyst which accelerates the ammonia addition to the alkene at a pressure which is conditioned by the function of the first section, i. e. 2 to 8 MPa. The reaction temperature alone : doesn't constitute any invention condition, but it must be such that it, together with a given catalyst, provides for practically applicable rate of amine forming. The ~ lower bound of the temperature of 220 °C is limited by kinetics, the upper bound 320 °C is limited by achievable equilibrium conversion under the system pressure.
A further condition for the selection of a temperature is the gaseous form of the mixture which leaves the second section.
A relatively great amount of gaseous reactants are circulated through the reaction system, while from the bottom of the first section liquid crude amine is withdrawn which is then purified by a common method. The crude amine contains a certain amount of starting substances, i. e. alkenes and ammonia. Circulation of the gaseous mixture through the sections is ensured by a suitable compressing machine which is able to work at a temperature of 80 to 120 °C. At a lower temperature the reactants would have condensated. Noting that the pressure loss in both sections and in the cooling zone is usually only 3 to 10 %, when referred to the pressure of the synthesis, the energy consumption for the reactant circulation is very low. At usual conditions of the amine synthesis from alkenes and ammonia at a pressure of 20 to 30 MPa a higher conversion of the alkene can be obtained, but the liquid reaction mixture must be rectified in a separate line, and isolated starting substances are recycled in the liquid phase. The reactants are thus evaporated twice, at first in rectifying columns, then before entering the reactor.
On the other hand the heat consumption at the bottom of the first section of the amine synthesis according to the present invention is very low, and the energy consumption for the inner circulation of gaseous reactants is also low. The energy costs in the synthesis according to the present invention are about a half of those for common procedures. Due to low energy consumption in the amine synthesis : according to the present invention it is possible to work also with very low conversion of alkenes in the second section which is important for the amination of less reactive alkenes, like propylene and ethylene.
The equipment for the operation at a pressure of 2 to 8 MPa is considerably cheaper than an equipment for common amine synthesis at a pressure of 20 to 30
MPa. : Molar ratio NHs/alkene which is determined by the alkene type plays a certain role in the amine synthesis according to the present invention. The higher the “ boiling point of the alkene, the higher molar ratio must be used. With increasing ammonia excess the equilibrium conversion of alkenes to amine is increasing on one hand, on the other hand the amount of reactants which circulate through the system of the first and second section is increased. If acidic heterogeneous catalysts are applied, strong sorption of ammonia decreases the addition rate. For example, if isobutylene is reacted to tert-butylamine using the zeolites ZSM-5 in the second section of the system and at a pressure of 4 MPa, the amine formation rate at a molar ratio NHs/isobutylene = 4 is 30 % less than that at the molar ratio of 2. When the method according to the present invention is used, the optimum molar ratio NHs/isobutylene at the entry into the second section lies just in the range of 2 to 4.
A high ammonia excess is necessary in the addition of ammonia to alkenes which boil at higher temperatures. For example, when producing cyclohexylamine from cyclohexene it is possible to circulate the gaseous reactants from the first to the second section at a pressure of 3 MPa only at a molar ratio of 15 to 20.
Example 1
The upper part of the first section is fed with a fresh mixture of isobutylene and ammonia using a pump, which mixture is, together with the condensate which runs off the dephlegmator, mixed in the central part of the first section with the : reaction mixture, cooled to a temperature of 120 °C, which is incoming from the first section. The second section is provided with a built-in packing having the ; efficiency of 15 equilibrium (theoretical) plates which is, together with the overall reflux ratio of 0.35, sufficient for separation of 95 % of tert-butylamine from the mixture. The gases which leave the dephlegmator have a temperature of 90 °C they are heated to 100 °C, and they are transported by means of a membrane compressor through a preheater to the second section which is filled with two litres of the ZSM-5-type zeolite catalyst in the form of compacts, where they react to : tert-butylamine at a temperature of 250 °C and a pressure of 3.9 MPa. The conversion of isobutylene to tert-butylamine is 5 % and the selectivity is 99.5 %. ~ The first section is fed with such an amount of fresh ammonia and isobutylene that 70 moles of isobutylene and 210 moles of ammonia per hour enter the second section. From the bottom of the first section which is heated to 165 °C liquid mixture is leaving which contains 50 % of tert-butylamine, approximately the same amount of isobutylene and only 0.02 % of isobutylene dimers.
Example 2
Using the same equipment as in Example 1, synthesis of 2-aminopropane from propylene and ammonia was performed at a temperature of 320 °C and a pressure of 5 MPa. Using a molar ratio NHs/propylene of 4 the conversion of alkenes to amine was 3 %. The first section of the synthesis system has worked at a reflux ratio of 0.25, ensuring separation of 95 % of amine, contained in the mixture incoming from the second section. In the upper part of the first section there was a temperature of 95 °C, bottom of the first section was heated to 134 °C. From the bottom of the first section crude 2-aminopropane, containing 7 % by weight of ammonia and 18 % by weight of propylene, has been withdrawn.
Ug
Claims (11)
1. A process of preparation of aliphatic amines by ammonia addition to alkenes in gaseous phase, catalyzed by homogeneous or heterogeneous catalysts, ' characterized in that the reaction system consists of two sections which are mutually interconnected and conditioned and of one cooling zone which work at a practically equal pressure of 2 to 8 MPa, while the starting ammonia and alkene enter the first section, where they are mixed with unreacted ammonia and alkene at the pressure of the synthesis, and the mixture enters the second section, where a partial chemical transformation of reactants to amine takes place, and the reaction mixture leaving the second section, passes the cooling zone and returns to the first section, where the separation of the gaseous mixture of unreacted ammonia and alkenes from the liquid crude amine takes place, which crude amine is further purified.
2. A process accordingtoclaim1, characterized in that the number of carbon atoms in the alkene is 2 to 8.
3. A method according to claim2, characterized in that the alkene is isobutylene.
4. A method according toclaim1, characterized in that the first section is provided with a built-in packing to intensify mutual counterflow contact of the gaseous and liquid phases with the aim to increase the separation efficiency.
5. A method according to claim 1, characterized in that a heterogeneous zeolite catalyst is used in the second section.
6. A method accordingto claim 5, characterized in that a zeolite catalyst of the ZSM-5-type is used in the second section.
PCT/SK00/00008 -0-
7. A method accordingtoclaim1, characterized in that the molar ratio of ammonia to alkene at the entry into the reactive section is 1.5 to 20.
8. A method according to claim 1, characterized in that the reaction mixture is cooled in the cooling zone to a temperature near the dew point.
9. A method according to claim 9, characterized in that the reaction mixture is cooled in the cooling zone to a temperature near the dew point by means of a heat exchange with the mixture which has been recycled from the separative section to the reactive section.
10.A process of preparation of aliphatic amines substantially as herein described with reference to examples 1 and 2.
11.A method of preparation of aliphatic amines substantially as herein described with reference to examples 1 and 2. AMENDED SHEET
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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ZA200209596A ZA200209596B (en) | 2002-11-26 | 2002-11-26 | Process for preparation of aliphatic amines. |
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Application Number | Priority Date | Filing Date | Title |
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ZA200209596A ZA200209596B (en) | 2002-11-26 | 2002-11-26 | Process for preparation of aliphatic amines. |
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ZA200209596B true ZA200209596B (en) | 2004-01-28 |
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ZA200209596A ZA200209596B (en) | 2002-11-26 | 2002-11-26 | Process for preparation of aliphatic amines. |
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2002
- 2002-11-26 ZA ZA200209596A patent/ZA200209596B/en unknown
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