Process for the continuous preparation of 1,2-propylene diamine (1,2-PDA) and dimethyldiethylene triamine (DMDETA)

Abstract

A process for the continuous preparation of 1,2-propylenediamine (1,2-PDA) and dimethyldiethylenetriamine (DMDETA) via reaction of monoisopropanolamine (MIPOA) with ammonia in the presence of hydrogen and a supported heterogeneous hydrogenation catalyst (catalyst), wherein the reaction is effected in the liquid phase at an absolute pressure in the range from 60 to 170 bar.

Claims

1. A process for the continuous preparation of 1,2-propylenediamine (1,2-PDA) and dimethyldiethylenetriamine (DMDETA) via reaction of monoisopropanolamine (MIPOA) with ammonia in the presence of hydrogen and a supported heterogeneous hydrogenation catalyst (catalyst), wherein the reaction is effected in a reactor in the liquid phase at an absolute pressure in the range from 60 to 170 bar and the reactor output is separated by distillation, wherein (1) the reactor output is supplied to a first distillation column K1 in which ammonia is removed at a side draw or overhead, (2) the bottoms output from K1 is supplied to a second distillation column K2 in which water is removed at a side draw or overhead, (3) the bottoms output from K2 is supplied to a third distillation column K3 in which 1,2-PDA is removed at a side draw or overhead, (4) the bottoms output from K3 is supplied to a fourth distillation column K4 in which DMDETA is removed in the bottoms, MIPOA is removed at a side draw and low boilers are removed overhead.

2. The process according to claim 1, wherein the ammonia obtained in step (1) and/or the MIPOA obtained in step (4) are recycled into the reaction.

3. The process according to claim 1, wherein the catalytically active composition of the catalyst, prior to the reduction thereof with hydrogen, comprises oxygen-containing compounds of aluminum and oxygen-containing compounds of copper, of nickel and/or of cobalt.

4. The process according to claim 1, wherein the catalytically active composition of the catalyst, prior to the reduction thereof with hydrogen, comprises oxygen-containing compounds of aluminum, of copper, of nickel and of cobalt and in the range from 0.2% to 5.0% by weight of oxygen-containing compounds of tin, calculated as SnO.

5. The process according to claim 1, wherein the catalytically active composition of the catalyst, prior to the reduction thereof with hydrogen, comprises in the range from 0.4% to 4.0% by weight of oxygen-containing compounds of tin, calculated as SnO.

6. The process according to claim 1, wherein the catalytically active composition of the catalyst, prior to the reduction thereof with hydrogen, comprises in the range from 5.0% to 35% by weight of oxygen-containing compounds of cobalt, calculated as CoO.

7. The process according to claim 1, wherein the catalytically active composition of the catalyst, prior to the reduction thereof with hydrogen, comprises in the range from 10% to 30% by weight of oxygen-containing compounds of cobalt, calculated as CoO.

8. The process according to claim 1, wherein the catalytically active composition of the catalyst, prior to the reduction thereof with hydrogen, comprises in the range from 15% to 80% by weight of oxygen-containing compounds of aluminum, calculated as Al.sub.2O.sub.3, 1.0% to 20% by weight of oxygen-containing compounds of copper, calculated as CuO, and 5.0% to 35% by weight of oxygen-containing compounds of nickel, calculated as NiO.

9. The process according to claim 1, wherein the catalytically active composition of the catalyst, prior to the reduction thereof with hydrogen, comprises in the range from 30% to 70% by weight of oxygen-containing compounds of aluminum, calculated as Al.sub.2O.sub.3, 2.0% to 18% by weight of oxygen-containing compounds of copper, calculated as CuO, and 10% to 30% by weight of oxygen-containing compounds of nickel, calculated as NiO.

10. The process according to claim 1, wherein the catalytically active composition of the catalyst does not comprise any rhenium and/or ruthenium.

11. The process according to claim 1, wherein the catalytically active composition of the catalyst does not comprise any iron and/or zinc.

12. The process according to claim 1, wherein the catalytically active composition of the catalyst does not comprise any oxygen-containing compounds of silicon and/or of zirconium.

13. The process according to claim 1, wherein the absolute pressure is in the range from 70 to 145 bar.

14. The process according to claim 1, wherein the reaction temperature during the reaction is 160-195° C.

15. The process according to claim 1, wherein the reaction is effected in the presence of 1.2% to 4.5% by weight of hydrogen, based on the amount of MIPOA used.

16. The process according to claim 1, wherein the ammonia is used in a 5-fold to 30-fold molar amount based on MIPOA.

Description

(1) FIG. 1 shows a particular embodiment of the process according to the invention, in which 1,2-PDA and DMDETA are obtained by means of a 4-column interconnection.

(2) The examples which follow serve to elucidate the invention without restricting it in any way.

EXAMPLES

(3) The catalyst is produced in accordance with example B3 according to WO2013/072289 A1.

DESCRIPTION OF THE EXPERIMENTS

(4) Results:

(5) The results are given in tables 1 and 2 for various molar ratios of ammonia to MIPOA.

Example 1 (According to the Invention, Table 1, Entry 1)

(6) A tubular reactor was filled with 47 ml of the catalyst. After activation of the catalyst under hydrogen, 18 g/h of a mixture of 1-aminopropan-2-ol and 2-aminopropan-1-ol (95:5), 42 g/h of ammonia (molar ratio 10) and 6 l (STP)/h of hydrogen (2.9% by weight based on MIPOA) were continuously passed into the reactor at 120 bar and a temperature of 165° C. After decompressing the reaction output to standard pressure, the composition was analyzed by gas chromatography. The product stream comprised 78.9% 1,2-PDA and 2.87% DMDETA and 12.2% 1-aminopropan-2-ol and 2.85% 2-aminopropan-1-ol (percentages relate to GF area %)

Example 2 (not According to the Invention, Table 1, Entry 2)

(7) A tubular reactor was filled with 47 ml of the catalyst. After activation of the catalyst under hydrogen, 18 g/h of 1-aminopropan-2-ol and 2-aminoproan-1-ol (95:5), 42 g/h of ammonia (molar ratio 10) and 6 l (STP)/h of hydrogen were continuously passed into the reactor at 120 bar and a temperature of 175° C. After decompressing the reaction output to standard pressure, the composition was analyzed by gas chromatography. The product stream comprised 79.4% 1,2-PDA and 2.61% DMDETA and 12.0% 1-aminopropan-2-ol and 2.74% 2-aminopropan-1-ol (percentages relate to GF area %)

(8) The remaining experiments were conducted analogously. The results are compiled in tables 1 and 2.

(9) The GC analysis for determination of the conversion and the selectivity was effected on a 30 m RTX-5 column. The samples were injected at 50° C. After five minutes at this temperature, heating was effected to 280° C. at 5° C./minute and the oven was held at this temperature for 5 minutes.

(10) TABLE-US-00001 TABLE 1 (results for MR = 10) Temperature/ Sel. for (1,2- Sel. for Sel. for (1,2-PDA + Entry MR Pressure/bar ° C. Conversion PDA) (DMDETA) DMDETA) 1 10 120 165 85% 93% 3% 96% (according to the invention) 2 10 200 175 85% 93% 3% 96% (not according to the invention) 3 10 120 180 98% 80% 6% 86% (according to the invention) 4 10 200 195 98% 77% 4% 81% (not according to the invention) MR = molar amount of ammonia based on MIPOA Conversion: Conversion based on MIPOA Sel. for (1,2-PDA): selectivity based on 1,2-PDA Sel. for (DMDETA): selectivity based on DMDETA Sel. for (1,2-PDA + DMDETA): selectivity based on 1,2-PDA and DMDETA The temperature was set so that the desired conversion of 85% or 98% was achieved.

(11) TABLE-US-00002 TABLE 2 (results for MR = 12) Temperature/ Sel. for (1,2- Sel. for Sel. for (1,2-PDA + Entry MR Pressure/bar ° C. Conversion PDA) (DMDETA) DMDETA) 1 12 120 165 87% 93% 3% 96% (according to the invention) 2 12 200 175 87% 93% 3% 96% (not according to the invention) 3 12 120 180 99% 82% 5% 87% (according to the invention) 4 12 200 195 99% 77% 3% 80% (not according to the invention) MR = molar amount of ammonia based on MIPOA Conversion: Conversion based on MIPOA Sel. for (1,2-PDA): selectivity based on 1,2-PDA Sel. for (DMDETA): selectivity based on DMDETA Sel. for (1,2-PDA + DMDETA): selectivity based on 1,2-PDA and DMDETA The temperature was set so that the desired conversion of 87% or 99% was achieved.

DISCUSSION OF THE RESULTS

(12) The results show that for conversions of 85% and 87% there is no reduction in the selectivities for 1,2-PDA and DMDETA when the pressure is reduced from 200 bar to 120 bar. At higher conversions (98% and 99%), an increase in the selectivities for 1,2-PDA and DMDETA can even be observed when the pressure is reduced from 200 bar to 120 bar. These results are surprising to those skilled in the art and cannot be derived from the prior art either alone or in combination with general technical knowledge.

(13) The formation of 1,2-PDA and DMDETA and also the (undesired) cyclization of the latter to give dimethylpiperazine can be described by means of the following reaction scheme:

(14) ##STR00001##

(15) Those skilled in the art would expect better selectivity in terms of 1,2-PDA to be achieved at higher pressures (200 bar) than at lower pressures (120 bar). The conversion of 1,2-PDA is effected in the liquid phase according to the invention. The higher the pressure, the greater the amount of ammonia dissolved in the liquid phase. The more ammonia available there, the more rapidly the MIPOA can react with it. That is to say, the probability of (still) unconverted MIPOA being converted in a possible side reaction decreases. Consequently, those skilled in the art would have expected that the selectivity for 1,2-PDA would also decrease in the event of a reduction in the pressure (from 200 bar to 120 bar).

(16) Likewise, those skilled in the art would have expected that better selectivity in terms of DMDETA would be achieved at higher pressures (200 bar) than at lower pressures (120 bar). The decrease in the selectivity for DMDETA results in particular from the fact that this cyclizes to give dimethylpiperazine with elimination of ammonia. Those skilled in the art would in fact expect the formation of dimethylpiperazine to be reduced at higher pressures in accordance with Le Chatelier's principle, since a higher pressure counteracts the elimination of ammonia. In this respect, the results presented in tables 1 and 2 show precisely the opposite to what those skilled in the art would have expected, and are therefore surprising.

(17) Distillative Work-Up

(18) The liquid reaction output is worked up in a distillation section.

(19) The following examples are based on simulation results obtained with the Aspen software from Aspen Technology, Inc. The thermodynamic parameters used in the program for the individual reaction products are based on published thermodynamic data or in-house measurements. The specification and the simulation of the specified distillation columns used were effected with the customary routines included in the software.

(20) To optimize the simulation model, the simulated results were compared with experimental results, where available, and the simulation model was aligned with the experimental results so that a good agreement between simulation and experimental data was achieved.

(21) The following examples were computed using the optimized simulation model.

(22) The workup was effected in four columns, as illustrated in FIG. 1.

(23) Ammonia column (distillation column K1)

(24) Excess ammonia is removed overhead by means of the ammonia column and recycled into the synthesis stage.

(25) Distillation conditions:

(26) Top pressure: 18 bar

(27) Top temperature: 45° C.

(28) Bottom temperature: 217° C.

(29) The bottoms of the ammonia column still comprise water, the products of value 1,2-PDA and DMDETA and also unconverted MIPOA, and are fed to the water column (distillation column K2).

(30) Water column (distillation column K2)

(31) The water of reaction is removed overhead in the column.

(32) Distillation conditions:

(33) Top pressure: 1.25 bar

(34) Top temperature: 104° C.

(35) Bottom temperature: 135° C.

(36) The bottoms (comprising MIPOA, 1,2-PDA, DMDETA and impurities) are supplied to the 1,2-PDA column (distillation column K3).

(37) 1,2-PDA column (distillation column K3)

(38) In the 1,2-PDA column, 1,2-PDA with a purity of ≥99.8% by weight is removed overhead.

(39) Distillation conditions:

(40) Top pressure: 0.95 bar (950 mbar)

(41) Top temperature: 119° C.

(42) Bottom temperature: 158° C.

(43) The bottoms (MIPOA, DMDETA and impurities) are supplied to the DMDETA column (distillation column K4).

(44) DMDETA Column (Distillation Column K4)

(45) The unconverted MIPOA is purified in the column before it is fed back to the reaction according to the invention. For this purpose, an azeotrope of MIPOA and methylpiperazine is discharged overhead.

(46) Distillation conditions:

(47) Top pressure: 0.76 bar (760 mbar)

(48) Top temperature: 147° C.

(49) Bottom temperature: 202° C.

(50) The reactant MIPOA which has been freed from dimethylpiperazines is obtained in gaseous form with a purity of ≥97% by weight at the side draw in the stripping section of the column. DMDETA with a purity of ≥96% by weight is obtained in the bottom and is discharged.