METHOXYPROPANOLS SEPARATION INCLUDING AZEOTROPIC DISTILLATION
20230271909 · 2023-08-31
Inventors
- Joaquim Henrique TELES (Ludwigshafen am Rhein, DE)
- Maria Angel SAN PIO BORDEJE (Ludwigshafen am Rhein, DE)
- Dylan SEGERS (Antwerp, BE)
- Dominic RIEDEL (Ludwigshafen am Rhein, DE)
- Emiel Jan KAPPERT (Ludwigshafen am Rhein, DE)
- Meinolf Weidenbach (Stade, DE)
- Franciscus Johannes Robertus VAN NEER (Hoek, NL)
Cpc classification
Y02P20/52
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
International classification
Abstract
The present invention relates to a process for separating 1-methoxypropan-2-ol in a stream S3 from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol, wherein the process comprises providing a stream S0 comprising 1-methoxypropan-2-ol, 2-methoxypro-pan-1-ol and water, and having a molar ratio of 1-methoxypropan-2-ol:2-methoxypropan-1-ol in the range of from 1:5 to 5:1. A further aspect of the invention also relates to 1-methoxypropan-2-ol obtained or obtainable from said process, as well as to a mixture of 1-methoxypropan-2-ol and 2-methoxypropan-1-ol, preferably obtained or obtainable from said process, which preferably comprises in the range of from 95 to 100 weight-% 1-methoxypropan-2-ol and ≤0.5 weight-% of 2-methoxypropan-1-ol, each based on the total weight of the mixture.
Claims
1.-13. (canceled)
14. A process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol, wherein the process comprises: (a) Providing a stream S0 comprising 1-methoxypropan-2-ol, 2-methoxypropan-1-ol and water, and having a molar ratio of 1-methoxypropan-2-ol:2-methoxypropan-1-ol in the range of from 1:5 to 5:1; (b) separating 1-methoxypropan-2-ol and 2-methoxypropan-1-ol from the stream S0 provided in (a) by distillation comprising subjecting the stream S0 provided in (a) to distillation conditions in a distillation unit comprising a distillation column B, obtaining a (top) stream S1 comprising 1-methoxypropan-2-ol, 2-methoxypropan-1-ol and water, which is enriched in 1-methoxypropan-2-ol and 2-methoxypropan-1-ol compared to the stream S0 and a bottoms stream S1a comprising water and being depleted of 1-methoxypropan-2-ol and 2-methoxypropan-1-ol compared to S0; wherein the distillation column B is operated at a pressure of ≥2 bar; (c) azeotropic distillation of the stream S1 obtained in (b) with an entrainer, comprising subjecting the stream S1 to azeotropic distillation conditions in an azeotropic distillation unit comprising a distillation column C, obtaining a bottoms stream S2 which is depleted of water and further enriched in 1-methoxypropan-2-ol and 2-methoxypropan-1-ol compared to the stream S1 and a top stream S2a comprising water and the entrainer; (d) separating 1-methoxypropan-2-ol from the stream S2 obtained in (c) by distillation, comprising subjecting the stream S2 obtained in (c) to distillation conditions in a distillation unit comprising a distillation column D, obtaining a stream S3 comprising ≥95 weight-% 1-methoxypropan-2-ol and ≤0.5 weight-% of 2-methoxypropan-1-ol, based on the total weight of stream S3, and a stream S4 comprising ≥95 weight-% 2-methoxypropan-1-ol based on the total weight of stream S4; (e) optionally distillative separation of the stream S2a comprising water and the entrainer obtained in (c) in a steam stripping column E using steam as stripping agent, obtaining a stream S5 comprising the entrainer, which is depleted of water compared to the stream S2a, and an aqueous stream S6 being depleted of the entrainer compared to S2a; and optionally recirculating at least a part of the stream S5 to (c).
15. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 14, wherein the thermal energy of stream S1 is partly transferred to a heat transfer medium stream HTMS1 after (b) and before step (c), obtaining a heat transfer medium stream HTMS1a having an increased thermal energy content compared to HTMS1; wherein HTMS1a is used to provide thermal energy to: the azeotropic distillation unit of step (c), and/or the distillation unit of (d).
16. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 15, wherein the thermal energy of the bottoms stream S1a of (b) is partly transferred to a heat transfer medium stream HTMS2, obtaining a heat transfer medium stream HTMS2a, which has an increased thermal energy content compared to HTMS2, wherein HTMS2a is used to provide thermal energy to the steam used as stripping agent in the steam stripping column of (e).
17. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 15, wherein the thermal energy provided by HTMS1a provides at least 90% of the energy demand of the azeotropic distillation unit of (c), and/or of the distillation unit of (d).
18. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 14, wherein stream S0 provided in (a) comprises water in an amount in the range of from 50 to 90 weight-%, and a mixture of 1-methoxypropan-2-ol and 2-methoxypropan-1-ol in an amount in the range of from 8 to 50 weight-%, each based on the total weight of stream S0, the remaining amount up to 100 weight-% being other components (impurities and solvent (MeOH)).
19. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 14, wherein stream S0 provided in (a) comprises 1-methoxypropan-2-ol and 2-methoxypropan-1-ol in a molar ratio in the range of from 1:4 to 4:1.
20. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 14, wherein stream S0 provided in (a) comprises propylene glycol dimethyl ether in an amount of ≥0.001 weight-%, based on the total weight of S0.
21. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 14, wherein the distillation column B comprised in the distillation unit according to (b) is operated at a pressure in the range of from 2 to 30 bar.
22. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 14, wherein ≥95 weight-% of stream S1, which leaves distillation column B over the top, consist of water, 1-methoxypropan-2-ol and 2-methoxypropan-1-ol; wherein stream S1 comprises water in an amount in the range of from 40 to 80 weight-%; and a mixture of 1-methoxypropan-2-ol and 2-methoxypropan-1-ol in an amount in the range of from 20 to 60 weight-%, each based on the total weight of stream S1, wherein the stream S1 comprises 1-methoxypropan-2-ol and 2-methoxypropan-1-ol in a molar ratio in the range of from 1:4 to 4:1.
23. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 14, wherein stream S1, which leaves distillation column B over the top, contains less than 0.05 weight-% of propylene glycol dimethyl ether, based on the total weight of S1.
24. The process for separating 1-methoxypropan-2-ol from an aqueous stream comprising 1-methoxypropan-2-ol and 2-methoxypropan-1-ol according to claim 14, wherein the stream S3 is removed as top stream from distillation column D, which comprises ≥95 weight-% 1-methoxypropan-2-ol and ≤0.5 weight-% of 2-methoxypropan-1-ol, each based on the total weight of stream S3; and/or wherein the stream S3 comprises less than 0.01 weight-% of propylene glycol dimethyl ether based on the total weight of stream S3.
25. 1-methoxypropan-2-ol obtained or obtainable from the process of claim 14.
26. A mixture of 1-methoxypropan-2-ol and 2-methoxypropan-1-ol obtained from the process of claim 14, which comprises in the range of from 95 to 100 weight-% 1-methoxypropan-2-ol and ≤0.5 weight-% of 2-methoxypropan-1-ol, each based on the total weight of the mixture.
Description
EXAMPLES
[0161] Simulations
[0162] All simulations were done with process simulation software Aspen Plus v.11. The components used in the process simulation and their characteristics respectively, were taken from the Dortmund Database.
Example 1: Separation of 1-methoxypropan-2-ol from an Aqueous Stream (S0) Containing 85 Weight-% of Water and 14.2 Weight-% of a Mixture of 2-methoxypropan-1-ol and 1-methoxypropan-2-ol
[0163] The feed stream S0 to column B was a variable stream and represented a stream from a propylene oxide production process, wherein a reaction mixture comprising propylene, water, methanol, and hydrogen peroxide had been contacted in an epoxidation zone with an epoxidation catalyst comprising a zeolitic material having a framework structure comprising Si, O, and Ti and being of framework type MFI (titanium silicalite-1 (TS-1)), and subjecting the reaction mixture to epoxidation reaction conditions in the epoxidation zone.
[0164] The obtained mixture comprising propylene oxide, water, and methanol had been removed as an effluent stream from the epoxidation zone. The effluent stream comprising propylene oxide, water, and methanol had been subjected to further separation and purification steps, wherein propylene oxide and water as well as parts of the organic solvent had been removed, resulting in a stream S0 comprising 1-methoxypropan-2-ol, 2-methoxypropan-1-ol and water and having a molar ratio of 1-methoxypropan-2-ol:2-methoxypropan-1-ol in the range of from 1:5 to 5:1. The composition of stream S1 varied as a function of the operating conditions of the propylene oxide production process (see influence of feed stream on the separation in Examples 2 and 3). An exemplary composition of stream S0 and exemplary compositions of the further streams S1 to S6 are indicated in Table 1; stream S0 as indicated in Table 1 of Example 1 contained 85 weight-% of water, 14.2 weight-% 2-methoxypropan-1-ol and 1-methoxypropan-2-ol and 0.02 weight-% methanol (MeOH).
TABLE-US-00001 TABLE 1 Compositions and parameters of streams S0 to S6, including benzene stream to column C and steam stream to column E Streams Steam Benzene (H.sub.2O (g), (stream stream directed directed to to column column S0 S1a S1 C S2 S2a S5 S6 E S3 S4 Parameter Temperature [° C.] 181 179.927 175.099 20 147.994 86.9 25 99.39 143 154.87 172.10 Pressure [bar] 10 10 10 2 2 2 1 1 1 3 3 Mass flow [kg/h] 11415 7371 4044 4.189 1623 23798 21373.61 2519 95 792.77 829.79 Components, indicated in weight-% 2-Methoxypropan- 7.26 5.83E−04 20.48 51.11 2.8E−05 8.06E−06 2.31E−05 5E−02 99.87 1-ol Water 85.17 99.11 59.98 1E−02 10.56 22.43 99.86 1 2.01E−02 Benzene 1 4.67E−08 86.73 34.16 9.49E−08 1-Methoxypropan- 6.95 9.42E−03 19.46 48.83 1E−02 4.44E−03 6.52E−03 99.92 3E−02 2-ol 1,1-Dimethoxy- ethane 1,1-Dimethoxy- 1E−03 1.34E−03 3.05E−08 1.5 4.84 2.92E−09 6.15E−08 propane 1,2-Propanediol 1E−02 1.55E−2 9.45E−8 2.22E−07 4.34E−07 (MPG) 1-Butanol 1E−03 2.27E−03 1.84E−03 1.16E−02 1.94E−02 3.33E−03 3.77E−03 2.87E−08 2,4-Dimethyl-1,3- 1.E−03 1.81E−03 3.9E−08 1.75E−01 2.39 4.02E−03 7.87E−08 dioxolane 2,6-Dimethyl-4- 1E−03 1.71E−03 7.04E−03 1.38E−02 heptanol 2-Butenal 1E−03 2.22E−03 4.9E−04 3.3E−02 3.82E−02 4.19E−03 9.99E−04 2.04E−13 2-Ethyl-4-methyl- 1E−03 1.55E−03 5.2E−06 1.24E−05 7.36E−08 2.41E−05 1,3-dioxolane 2-Hexanone 1E−01 1.56E−01 7.04E−01 2.38E−02 2.43E−02 1.15E−08 4.19E−03 1.37 2-Methylcyclo- 1E−03 1.55E−03 5.2E−06 1.24E−05 7.36E−08 2.41E−05 hexanol 2-Methylpentanal 4E−03 4.85E−03 2.81E−02 7.82E−03 2.71E−03 3.06E−14 1.68E−04 5.48E−02 2-Propen-1-ol 1E−03 2.51E−03 3.26E−06 2.67E−03 1.14E−02 4.53E−03 6.64E−06 4-Methyl-1,3- 1E−03 3.53E−10 2.76E−03 7.03E−03 1.63E−06 6.9E−07 5.13E−07 4.19E−05 1.37E−02 dioxolane Acetaldehyde 1E−0 1.46E−03 1.27E−10 1.85E−01 1.32E−01 1.56E−03 1.99E−11 Acetone 1E−03 2.06E−03 1.5E−08 7.51E−03 5.71E−02 4.5E−03 3.01E−08 Dimethoxy- 1E−03 1.99E−03 4.52E−09 3.7E−01 1.16E−01 1.69E−03 9.04E−09 methane Dipropylenegly- 2E−02 3.1E−02 1.04E−04 2.47E−04 1.47E−06 4.82E−04 col (DPG) Ethanol 1E−03 2.28E−03 6.37E−08 1.52E−03 1.32E−02 4.53E−03 1.28E−07 Hydroxyacetone 1E−03 1.51E−03 7.55E−05 1.81E−04 2.33E−12 3.55E−04 2-Propanol 1E−03 2.03E−03 1.33E−07 3.1E−03 2.71E−02 4.52E−03 2.68E−07 Methanol 1.99E−02 4.84E−02 1.58E−07 1.54E−02 1.82E−01 9E−02 3.16E−07 Methylacetate 1E−03 1.68E−03 1.11E−08 1.11E−01 2.54E−02 4.02E−03 2.23E−08 Methylformate 1E−03 1.54E−03 1.81E−05 3.12E−12 7.14E−05 2.31E−03 2.7E−05 Propyleneoxide 1E−03 1.59E−03 5.57E−10 2.63E−01 8.46E−02 2.63E−03 1.1E−09 Tripropylene 2E−02 3.1E−02 7.75E−10 6.97E−12 glycol (TPG) Dipropylene 5.1E−01 7.9E−01 4.63E−06 1.09E−05 2.13E−05 glycol mono methyl ether (DPGME) Propylene glycol 6.5E−03 9.23E−03 1.56E−03 2.71E−03 2.4E−04 2.06E−04 7.01E−04 5.52E−03 6.93E−14 dimethyl ether (1,2-Dimethoxy- propane)
[0165] The expression “E-xx” in Table 1 represents 10.sup.−xx, wherein “xx” is here a placeholder for the respective number indicated in Table 1.
[0166] Column B was a pre-distillation column, used to enrich the mixture of 1-methoxy-2-propanol and 2-methoxy-1-propanol contained in stream S0. In column B, the mixture of 1-methoxy-2-propanol and 2-methoxy-1-propanol was separated from side components. in order to ensure that the final product 1-methoxy-2-propanol has a purity of >95 weight-%, preferably ≥98 weight-%, more preferred ≥99 weight-%, more preferred ≥99.7 weight-%. Column B had 20 theoretical stages and was operated at 10 bar. Feed stream S0 entered the column B at theoretical stage 17 (between stage 17 and 18). The temperature at the top was 177° C. and at the bottom 180° C. Column B was operated with a reflux ratio of 4.93 g/g and 9.17 MW were needed in the reboiler and 9.186 MW in the condenser. An azeotropic mixture of water, 1-methoxy-2-propanol and 2-methoxy-1-propanol was removed from column B over the top (stream S1:60 weight-% water, 40 weight-% mixture of 1-methoxy-2-propanol and 2-methoxy-1-propanol). Negligible amounts of side components were removed from column B as bottoms stream S1a, which was afterwards send to a subsequent water treatment.
[0167] Stream S1 was optionally flashed before entering column C to reduce the heat demand in column C, wherein the stream S1 was transferred to a further flash column, where the pressure was reduced from 10 bar to 2 bar. This decreased the temperature of stream S1, which in turn reduced the heat demand in column C.
[0168] Column C was an azeotropic distillation column working with benzene as entraining agent with 16 theoretical stages operated at 2 bar. The temperature at the top was 89.5° C. and at the bottom 148° C. Column C was operated with a reflux ratio of 18.12 g/g and 7.38 MW were needed in the reboiler and 7.7 MW in the condenser. As entrainer in Column B, benzene was used. A bottom streams S2 was removed from Column C, wherein ≥85 weight-% of S2 consisted of 1-methoxy-2-propanol and 2-methoxy-1-propanol. A stream S2a consisting to more than 90 weight-% of water and benzene was removed from column C over the top and further proceeded in column E.
[0169] Stream S2 was transferred to column D, which was a distillation column with 48 theoretical stages operated at 3 bar. The temperature at the top of column D 156° C. and at the bottom 172° C. Column D was operated with a reflux ratio of 12.2 g/g and 1.245 MW were needed in the reboiler and 1.23 MW in the condenser. From column D, a stream S3 was removed over the top comprising ≥95 weight-% 1-methoxypropan-2-ol and ≤0.5 weight-% of 2-methoxypropan-1-ol (as in Table 1 indicated, 0.05% 2-methoxypropanol in S3), based on the total weight of stream S3. As bottoms streams, a stream S4 was removed, wherein S4 comprised 95 weight-% 2-methoxypropan-1-ol based on the total weight of stream S4 (as in Table 1 indicated, 300 ppm of 1-methoxypropanol in S4).
[0170] Column E was used to recover the benzene—via steam stripping. Column E was a steam stripping column with 10 theoretical stages operated at 1 bar. A stream of 98 kg/h 4 bar steam (H.sub.2O.sub.gaseous) was used as the stripping agent to separate completely the water from the entrainer, avoiding any agent losses and assuring the water specifications before water treatment. The temperature at the top of column E was 81.7° C. and at the bottom 99.4° C. Stream S6 which left column E as bottoms stream was cooled down to about 25° before subsequent water treatment and did not contain any entrainer.
[0171] Heat Integration
[0172] An important aspect of the separation process in including columns B to E and optionally F was the heat integration, because it reduces significantly the investment costs in terms of steam. For the heat integration there were several possibilities, 5 thereof were simulated: [0173] 1. The thermal energy (heat) of the condenser of column B, i.e. of stream S1, was used to heat the reboiler of column C in that thermal energy of stream S1 was partly transferred to a heat transfer medium stream HTMS1 after step (b) and before step (c) in a heat exchanger H, wherein a heat transfer medium stream HTMS1a was obtained which had an increased thermal energy content compared to HTMS1. The heat transfer medium stream HTMS1a was used to provide thermal energy to a heat exchanger unit, which supplied the reboiler of column C (see
[0179] The heat transfer medium of HTMS1/HTMS1a and of HTMS2/HTMS2a was steam (H.sub.2O.sub.gaseous).
[0180] This example demonstrated that 1-methoxypropanol-2 with a purity of 99.92 weight-% could be obtained with an isolation yield of 99.84%. Additionally, 2-methoxypropanol-1 with a purity of 99.87 weight-% could be obtained with an isolation yield of 99.99%. The power required for the separation was in the best constellation just 8.9 MW or 7.12 MW-h/t of pure methoxypropanols (1250 kg/h of pure methoxypropanols).
Example 2: Influence of the MeOH Concentration in the Feed Stream S0 on the Separation of 1-methoxy-2-propanol
[0181] Herein, the same set-up with the same columns B to E as in Example 1 was used, the only difference to Example 1 was that in stream S0 the amount of MeOH contained in the stream was assumed to be 0.1 weight-%.
[0182] Herein, the same set-up with the same columns B to E as in Example 1 was used, the only difference to Example 1 was that in stream S0 the amount of MeOH contained in the stream was assumed to be 0.1 weight-%.
[0183] The simulations were made according to a value of 0.1 weight-% MeOH, resulting in no presence of MeOH in the water streams that have to be send to a subsequent water treatment (streams S1a, S6).
[0184] In case of presence of more MeOH in the stream S0 (assumed here is an extreme value of 1 weight-% MeOH),—simulations were performed, indicating that the MeOH would go completely to the feed stream of column C (S1) and it would be an increase from 0.048 weight-% in Example 1 (0.1 weight-% MeOH in S0) to 2.76 weight-% in Example 4 (1 weight-% MeOH in S0). The MeOH would go completely to the water stream (S6), 114.15 kg/h MeOH in S0 that go to S6 with 113.984 and 0.116 to S5 back into column C.
[0185] There were two possibilities to operate in case of 1 weight-% MeOH in S0: first, to separate the MeOH before entering the column C, or second, to separate it from stream S6 before going to a subsequent water treatment. For both possibilities, the MeOH can be to 100 weight-% separated from the water with a further distillation column F, needing 1.07 MW in the condenser and 1.09 MW in the reboiler, 10 theoretical stages and 1 bar.
[0186] The heat transfer medium of HTMS1/HTMS1a and of HTMS2/HTMS2a was steam (H.sub.2O.sub.gaseous).
[0187] This example demonstrated that in S3, 1-methoxypropanol-2 with a purity of 99.92 weight-% could be obtained with an isolation yield of 99.22%. Additionally, 2-methoxypropanol-1 with a purity of 99.87 weight-% could be obtained in S4 with an isolation yield of 99.94%. The power required for the separation was just 10.97 MW or 8.77 MW-h/t of pure methoxypropanols (1250 kg/h methoxypropanols).
[0188] Table 2 lists streams S0, S1, S11a, S2, S2a and S5 for the composition with 1 weight-% MeOH in S0.
TABLE-US-00002 TABLE 2 streams for a composition of S0 with 1 weight-% MeOH Streams Benzene (stream directed to column S0 S1a S1 (c) S2 S2a S5 Temperature [° C.] 181 179.93 177.47 20 147.88 83.7 25 Pressure [bar] 10 10 10 2 2 2 1 Mass flow [kg/h] 11415 7290 4125 3.7 1623 25100 22595 Components, indicated in weight-% (unless otherwise noted) 2-Methoxypropan-1-ol 7.26 6E−04 20.16 51.11 2.8E−05 281 ppb Water 84.19 99.11 58.22 1E−02 10.31 0.44 Benzene 1 0 84.92 94.89 1-Methoxypropan-2-ol 6.95 9.4E−03 19.13 48.83 1E−02 1.03E−03 1,1-Dimethoxyethane 1,1-Dimethoxypropane 1E−03 1.0E−03 1.58 1.76 1,2-Propanediol (MPG) 1E−02 1.55E−2 1 ppb 2.0E−06 1-Butanol 1E−03 2.22E−03 1.8E−03 1.14E−02 2.88E−2 2,4-Dimethyl-1,3-dioxolane 1.E−03 1.6E−03 0.63 0.69 2,6-Dimethyl-4-heptanol 1E−03 1.5E−03 7.0E−03 2-Butenal 1E−03 2.1E−03 5.0E−4 3.24E−02 3.73E−03 2-Ethyl-4-methyl-1,3-dioxolane 1E−03 1.5E−03 5.2E−06 1.22E−05 2-Hexanone 1E−01 1.3E−03 7.0E−03 2.0E−03 2.0E−04 2-Methylcyclohexanol 1E−03 1.5E−03 5.2E−06 1.22E−05 2-Methylpentanal 4E−03 3.6E−03 2.81E−02 7.9E−03 2.6E−03 2-Propen-1-ol 1E−03 2.51E−03 3.2E−06 2.7E−03 1.13E−02 4-Methyl-1,3-dioxolane 1E−03 2.7E−03 7.0E−03 1.6E−06 7 ppb Acetaldehyde 1E−0 1.2E−03 2E−01 .0.2 Acetone 1E−03 1.9E−03 7.5E−03 5.57E−2 Dimethoxymethane 1E−03 1.8E−03 5.5E−01 0.62 Dipropyleneglycol (DPG) 2E−02 3.1E−02 1.0E−04 2.0E−04 Ethanol 1E−03 2.3E−03 1 ppb 1.5E−03 1.3E−03 Hydroxyacetone 1E−03 1.5E−03 1E−04 2.0E−04 2-Propanol 1E−03 1.9E−03 1 ppb 3.1E−03 2.67E−03 Methanol 1 2.76 75 ppb 4.71E−01 5.34E−04 Methylacetate 1E−03 1.5E−03 3.6E−01 2.92 Methylformate 1E−03 1.5E−03 164 ppb 1.0E−04 2.6E−03 Propyleneoxide 1E−03 1.7E−03 5.4E−01 0.58 Tripropyleneglycol (TPG) 2E−02 3.1E−02 0 Dipropyleneglycol monomethyl 5.1E−01 7.9E−01 41 ppb 1.08E−05 ether (DPGME) Propylene glycol dimethyl ether 6.5E−03 9.2E−03 1.4E−03 2.7E−03 2.0E−04 2.0E−04 (1,2-Dimethoxypropane)
Example 3: Influence of the Water Concentration in the Feed Stream S0 on the Separation of 1-methoxy-2-propanol
[0189] Herein, the same set-up with the same columns B to E as in Example 1 was used, the only difference to Example 1 was that in stream S0 a different water concentration was simulated to investigate its influence on the separation of 2-methoxypropan-1-ol and 1-methoxypropan-2-ol. From a composition with 85 weight-% water and 14.2 weight-% of 2-methoxypropan-1-ol and 1-methoxypropan-2-ol up to a composition with 55 weight-% H.sub.2O and 43 weight-% 2-methoxypropan-1-ox and p-methoxypropan-2-ol, the separation could be done successfully as described in Example 1. The amount of methoxypropanols in the feed was higher in Example 3, therefore the amount over the top in column B was higher because there was more amount of the azeotrope water/methoxypropanols. Therefore, a bit more amount of fresh benzene was needed to break the azeotrope in column C, 6 kg/h instead of 4.2 kg/h in Example 1 (see Table 3).
[0190] In Column E, 200 kg/h of steam were required instead of only 95 kg/h as in Example 1.
[0191] The stream containing the 2 MOP isomers, S2, contained according to the specifications, 100 ppm water. A stream S0 with less water than 55 weight-% and/or more than 43 weight-% 2-methoxypropan-1-ol and 1-methoxypropan-2-ol would not be possible because it would be under the azeotrope point. Table 3 lists streams S0, S1, S1a, S2, S2a and S5 for the composition with 55 weight-% H.sub.2O and 43 weight-% 2-methoxypropan-1-ol and 1-methoxypropan-2-ol.
TABLE-US-00003 TABLE 3 streams for a composition of S0 with 55 weight-% H.sub.2O and 43 weight-% 2-methoxypropan-1-ol and 1-methoxypropan-2-ol. Streams Benzene (stream directed to column S0 S1a S1 (c) S2 S2a S5 Temperature [° C.] 181 192.32 177.47 20 147.88 87.82 25 Pressure [bar] 10 10 10 2 2 2 1 Mass flow [kg/h] 11415 86.79 11328.21 6 5048 62372 56086 Components, indicated in weight-% (unless otherwise noted) 2-Methoxypropan-1-ol 22.26 4.87E−03 22.43 50.360 356 ppb 3.62E−05 Water 55.17 25.25 55.41 100 ppm 10.75 0.41 Benzen 1 1E−06 89.12 99.46 1-Methoxypropan-2-ol 21.95 5.13E−03 22.11 49.61 1E−02 1.04E−03 1,1-Dimethoxyethane 1,1-Dimethoxypropane 1E−03 1E−03 0.055 6.94E−02 1,2-Propanediol (MPG) 1E−02 1.32 2.09E−08 1 ppb 1-Butanol 1E−03 1E−03 6E−04 4E−03 4.32E−03 2,4-Dimethyl-1,3-diox- 1.E−03 1.E−03 1.15E−02 1.26E=−02 olane 2,6-Dimethyl-4-heptanol 1E−03 1E−03 2.3E−03 2-Butenal 1E−03 1E−03 2E−04 1.15E−02 1.27E−03 2-Ethyl-4-methyl-1,3-di- 1E−03 1.31E−01 1.21E−06 54 ppb oxolane 2-Hexanone 1E−03 1E−03 2.3E−03 1E−04 5.75E−05 2-Methylcyclohexanol 1E−03 1.31E−01 1.21E−06 54 ppb 2-Methylpentanal 4E−03 4E−03 9E−03 1.5E−03 1.71E−03 2-Propen-1-ol 1E−03 2.51E−05 15 ppb 1E−03 8.6E−04 4-Methyl-1,3-dioxolane 1E−03 3.36E−09 1.01E−03 2.3E−03 5E−06 6E−07 Acetaldehyde 1E−0 1.01E−03 5.8E−03 2.67E−03 Acetone 1E−03 1.01E−03 2.6E−03 2.67E−03 Dimethoxymethane 1E−03 1.01E−03 1E−06 5.8E−03 6.3E−03 Dipropyleneglycol 2E−02 2.68 2.42E−05 1E−05 Ethanol 1E−03 1.01E−03 6E−04 4E−04 Hydroxyacetone 1E−03 1.3E−01 9.03E−06 374 ppb 2-Propanol 1E−03 1.01E−03 1 ppb 1.1E−03 1E−03 Methanol 1.99E−02 2.0E−02 1 ppb 5.8E−03 2.3E−03 Methylacetate 1E−03 1E−03 7E−03 7.6E−03 Methylformate 1E−03 1.31E−01 2.6E−06 1.24E−05 128 ppb Propyleneoxide 1E−03 1E−03 5.6E−03 6E−03 Tripropyleneglycol (TPG) 2E−02 2.63 4.07E−11 Dipropyleneglycol mono- 5.1E−01 67 1.03E−06 48 ppb methylether (DPGME) Propylene glycol dimethyl 6.5E−03 5.7E−01 2.18E−03 3.93E−03 5E−04 4E−04 ether (1,2-Dimethoxypro- pane)
[0192] From Examples 1 to 3, as well as from Tables 1 to 3, it could be seen that operating column B at a pressure ≥2 bar (here 10 bar), resulted in a separation of propylene glycol dimethyl ether: stream S1, after column B had only a content of propylene glycol dimethyl ether of less than 0.06 weight-%, preferably less than 0.05 weight-%, more preferred less than 0.005 weight-%, more preferred less than 0.004 weight-%, more preferred less than 0.002 weight-%, of propylene glycol dimethyl ether, based on the total weight of S1.
[0193] The example demonstrated that 1-methoxypropanol-2 with a purity of 99.92 weight-% could be obtained as S3 with an isolation yield of 99.86%. Additionally, 2-methoxypropanol-1 with a purity of 99.94 weight-% could be obtained as S4 with an isolation yield of 99.91%. Especially stream S3, which contained 1-methoxypropanol-2, had less than 0.06 weight-%, preferably less than 0.01 weight-%, more preferred less than 0.008 weight-%, more preferred less than 0.007 weight-%, more preferred less than 0.008 weight-%, of propylene glycol dimethyl ether based on the total weight of stream S3.
[0194] The power required for the separation was 16.64 MW, or 3.3 MW-h/t of pure methoxypropanols (5046 kg/h pure methoxypropanols). Further, it could be seen that also other impurities in the final products were significantly reduced when column B was operated at a pressure ≥2 bar.
Example 4
[0195] Example 1 was recalculated but the pressure in column B was reduced to 3.5 bar while keeping all the other parameters constant.
[0196] At lower pressure it was still possible to energetically couple the towers, but not as efficiently, causing the energy consumption to increase to 10 MW which is almost 5% higher than in example 1. Surprisingly the separation of by-products at lower pressure is also less efficient. Table 4 shows that the concentration of several by-products in stream S1 is considerably higher than in example 1.
TABLE-US-00004 TABLE 4 Concentration of specific impurities in S1 at different pressures Concentration in S1 (weight-ppm) Example 4 Example 1 Components (3.5 bar) (10 bar) 2-Ethyl-4-methyl-1,3-dioxolane 0.087 0.052 2-Methylcyclohexanol 0.087 0.052 Dipropyleneglycol 1.66 1.04 Hydroxyacetone 1.31 0.75 Methylformate 20.8 0.18 Propylene glycol dimethyl ether 29.7 15.6 (1,2-Di-methoxypropane)
[0197] The higher concentration of side components in stream S1 led to a lower purity of the obtained products. The losses of entrainer also increased to 5 kg/h, which was almost 20% higher than in example 1. Due to the higher concentration of by-products in stream S1 and therefore in stream S2, the isolation yield and purity of the obtained products also decreased, the purity of 1-methoxypropan-2-ol in S3 decreased from 99.92 weight-% in Example 1 to 99.91 weight-% in Example 4 (0.10% less) and the isolation yield of 1-methoxypropan-2-ol also decreases from 99.85% to 99.31% (0.54% less).
[0198] The power required for the separation increased to 10 MW or 8 MW-h/t of pure methoxypropanols (1250 kg/h of methoxypropanols) as compared to only 8.9 MW or 7.12 MW-h/t of pure methoxypropanols using the inventive process.
[0199] The example demonstrated that by using the inventive method 1-methoxypropanol-2 with a purity of 99.91 weight-% could be obtained in S3 with an isolation yield of 99.31%. Additionally, 2-methoxypropanol-1 with a purity of 99.86 weight-% could be obtained as S4 with an isolation yield of 99.87%.
Comparative Example 1
[0200] Herein, the same set-up with the same columns B to E as in Example 1 was used, the difference to Example 1 was that in column B a pressure of 1 bar was used and, consequently, in column C a pressure of also 1 bar had to be used.
[0201] Having 1 bar in column B influenced the pressure of the rest of the columns in the process. In Example 1, column B was designed for 10 bar and column C for 2 bar, creating a pressure drop helping to reduce drastically the heat demand in the second reboiler of column C. Column D was designed for 3 bars for the separation of the isomers 1-methoxylpronan-2-ol and 2-methoxypropan-1-ol, after optimizing the heat in the reboiler of column D. Using only 1 bar in column B resulted in a loss for the heat integration with column C, and also for the heat demand in column B (reboiler). This resulted in the fact that if column B was operated at 1 bar, column C also had to be operated at 1 bar. Table 5 shows the amounts of water and of specific impurities in stream S1 when column B was operated at 1 bar, compared to the amounts of water and the same specific impurities in S1 when column B was operated at 3.5 bar and at 10 bar (as in Example 1), Table 6 shows a reduced overview of all streams when column B, and consequently, all further columns C, D and E, were operated at 1 bar.
TABLE-US-00005 TABLE 5 Water and specific impurities in S1 when column B was operated at different pressures Concentration in S1 (weight-ppm, unless otherwise indicated) Components 1 bar 3.5 bar 10 bar (Example 1) Water 72.87 62.48 59.98 weight-% weight-% weight-% Dipropyleneglycol 2.52 1.66 1.04 Hydroxyacetone 3.16 1.31 0.75 Methylformate 13.5 20.8 0.18 Propylene glycol 91.8 29.7 15.6 dimethyl ether
TABLE-US-00006 TABLE 6 Parameters and content of specific compounds of streams S0 to S5, including benzene streams to column C and steam stream to column E for all columns B to E operated at 1 bar. Streams Ben- Steam zene Benzene (H.sub.2O S1 (fresh, (recycled, (g), heated stream stream stream up (feed directed directed directed to to to to column column column column S0 S1a S1 C) C) C) S5 S2 S2a E) S3 S4 Parameter Tem- 181 99.66 95.3 175 20 68.9 99.57 124.67 68.92 143 115.84 131.42 perature [° C.] Pressure 1 1 1 1 1 1 1 1 1 4 1 1 [bar] Mass 11415 5394.805 6020.195 6020.195 1.13 48160 176.17 1621.5 52736 400 792.93 828.617 flow [kg/h] Components, indicated in weight-% 2-Meth- 7.26 1.00E−02 13.87 13.87 3.12E−07 4.77E−07 51.07 3.09E−07 5.00E−02 99.89 oxy- propan- 1-ol Water 85.17 98.8 72.87 72.87 0.29 91.74 0.01 8.91 100 1.99E−02 0.00E+00 Benzene 100 99.52 7.18 2.36E−09 90.91 4.77E−09 0.00E+00 1-Meth- 6.95 2.46E−06 13.18 13.18 0.8267E−03 1.42E−03 48.84 0.08E−02 99.86 3.00E−02 oxy- propan- 2-ol . . . Propy- 6.50E−03 3.56E−03 9.18E−03 9.18E−03 9.37E−04 4.09E−03 2.37E−02 1.18E−03 4.82E−02 6.43E−12 lene glycol dimethyl ether (1,2-Di- meth- oxypro- pane)
[0202] Operation of column B at 1 bar resulted in more water going over the top of column B with stream S1, which included the isomers 1-methoxylpronan-2-ol and 2-methoxypropan-1-ol to the column C. Further, more impurities were transferred together with the water/1-methoxylpronan-2-ol, 2-methoxypropan-1-ol azeotrope to column C; S1 contained 9.18×10.sup.−3 weight-% propylene glycol dimethyl ether (more than the fivefold amount than at 10 bar as in Example 1).
[0203] Based on column B operated at only 1 bar, column C and all further columns D and E had to be also operated at 1 bar. For column C operated at 1 bar, the heat demand in the reboiler of column C increased. As outlined in Example 1, Column 2 was designed to break the azeotrope of water and 1-methoxylpronan-2-ol, 2-methoxypropan-1-ol with benzene as entrainer.
[0204] In order to have a sufficient water removal in column C, i.e. to have a water content in S2 of at the outmost 100 ppm, based on the total weight of S2, the reboiler of column C required thermal energy in an amount of 50.125 MW. Furthermore, an additional heat exchanger was required to heat up stream S1 before entering column C in order to achieve a temperature of S1 of 175° C. in accordance with S1 of Example 1 since S1, if column B was operated at only 1 bar, had only a temperature of 93.5° C. Further, in view of the higher amount of water, which left column C via stream S2, it was necessary to add a benzene separation unit, for example, a decanter, between columns C and E. Benzene separated in said decanter from stream S2a had to be recycled to column C, otherwise, the demand on fresh benzene would have been very extensive. Furthermore, in order to separate water and benzene efficiently in column E, it was necessary to add 400 kg/h steam at 143° C. and 4 bar in column E.
[0205] In view of the much higher energy demand when column B is operated at 1 bar, no heat integration was possible: operating column B at only 1 bar required an energy intake in the reboilers of columns B, C and D of 70.8 MW. Additionally, 400 kg/h of 4 bar stream (143° C.) were required in column E to separate the benzene from the water.
[0206] Also the impurity content in the final stream S3 was higher when column B was operated at 1 bar: The propylene glycol dimethyl ether content in S3, based on the total weight of S3, was 0.0482 weight-% compared to only 0.00552 weight-% as in Example 1. That is, operating column B, and, consequently, also the further column C at 1 bar did not allow to have less than 0.006 weight-% of propylene glycol dimethyl ether in S3 based on the total weight of S3.
[0207] Further, even if much more energy is applied to the process, also the purity of S3 regarding 1-methoxypropan-2-ol was still a bit worse compared to Example 1: If column B was operated at 1 bar, 1-methoxypropanol-2 with a purity of only 99.86 weight-% could be obtained as S3.
SHORT DESCRIPTION OF THE FIGURES
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CITED LITERATURE
[0213] U.S. Pat. No. 5,723,024 A [0214] EP 1 375 462 A1 [0215] EP0425893A [0216] DE 10233388 A1 [0217] US 2004/0000473 A1 [0218] CN 103342631 [0219] CN 103992214