DE1568836A1 - Process for separating mixtures - Google Patents

Description

PATE N TA N WALTE

DR.-ING. H . FINCKE DIPL.-ING. H . B O hl R DIPL-ING. S. STAEGER

Telephone: 22 49 41

S MUNICH 5, Müllerstrasse 31

• Λ 196ß

Folder 20 726 Case H, 18334

description

sum patent application

der ü'i: cma Imperial ChemiegQ. Industries Limited London S ₀ W ₃ l / England

"Procedure for! 'Running mixtures"

ΡΗΙΟΗΙϊΒίχ 10ο ϊ-iai 1965 - Great Britain

The invention relates to the separation of mixtures of propyleno; i: yd mxd methyl formate,

Since "erfinflungsg-siiiäßs process for separating propyl anoxirö ii'iis Gei-iischöjfi ₃ v / slchs Propylenoaycl and Mefcbj-.Lforraiat Q.achali; on _r bösueirb therein ₉ dae mixture under a Yerwsndung

BAD ORIGiNAi

009829/1668

Extractive distillation of hydrocarbon solvents »

The hydrocarbon solvents are those which are less volatile than propylene oxide and are liquid under the distillation conditions. They bind the preferred solvents are straight-chain and branched paraffin coal substances having 5 to 10 carbon atoms such as hexane and heptane; naphtheni ehe hydrocarbons with 6 to 8 carbon atoms, such as Cyclohexane and ethylcyclohexane, and aromatic hydrocarbons having 6 to 8 carbon atoms, such as benzene and toluene.

The invention can therefore be carried out by adding a mixture containing propylene oxide and methyl formate in one Fractionating column distilled, being at a point in the column that is higher than that at which the Mixture is introduced, a straight-chain or branched paraffin hydrocarbon with 5 to 10 carbon atoms, a naphthenic hydrocarbon with 6 to 8 carbon atoms or an aromatic hydrocarbon with 6 to 8 Feeds carbon atoms, wins a stream from the column at the top which contains methyl formate, at the bottom of the column wins a stream which contains the extractive solvent and propylene oxide and separated the propylene oxide from the extractive solvent

009829/1668 ^ p ₀ R _l01 NAl

In practice, the separation can be made in two fractions! carried out v / ground, the first column having an upper section containing a solvent stripping section (stripping section) represents, and has a lower portion representing an extraction abBOhnitt, and the second Column a solution stripping column for the separation of propylene oxide is from the solvent.

The propylene oxide / methyl chloride mixture is introduced at a central point in the extraction section of the first column and the solvent is discharged from the top of the extraction section. Methyl formate is taken off at the top of the solvent stripping section of the first column, and the propylene oxide / solvent barrel is passed from the bottom of the extraction section to the second column. Propylene oxide is taken from the top of this column and the solvent sump is returned to the first column. If desired, of course, two columns can be used instead of a single lower column.

If the solvent used is clearly volatile under the extraction conditions, a suitable proportion of solvent mixed with the propylene oxide / methyl formate charge is preferably used in addition to the separate supply of the solvent

RAD ORiCi ".

^8AD ° ^rt 0 0 9 8 2 9/1668

eollte over 40 ββν · £ and Toraugeweiee over 90 0 «ir» j £ dee total weight ee which at all points la ftrtritlrti o — fttfitmf tt Hand-held liquid must be kept.

Particularly refined coal solvents such as toluene and methylcyclohexane, which increase the volatility of methyl formate in comparison with propylene oxide and have a low relative volatility of deterioration of propylene oxide or methyl formate and do not form any egeotropic properties. So eind toluene and hexane easily ron by Deetillation Propyleneiyd mA severable.

file Tor lying JSrfindung let on Geeieche ipwandbar, m erhältnieee ron Propylenoayd tu Methylforeiat Mi fierelefe τοπ 1: containing 100 bie 10Oi 1, and let eehr worth roll mm treating Gejnieehen when e'e insgeeaat wenigetejM 50 percent by £ and romugeweiee wenigetene $ 0 öew. «J6 Prefgrlenoxgrd plue contain methyl formate. Previously, the oeeieche la weeentliohen only contain new propylene oxide and Ife & hydroformate, and may contain 60 to 95% 20 to 5 % methyl formate, beeogeax may contain. Since other parts of the bed are in front, the separation generally occurs to whom. Propylene oxide τοη lfeth / Iforai «t according to the invention not, but let the separated

_BAD 0RiG ^ ^AL

oxide and / or methyl formate with the other component or mixed with the other ingredients.

It provides in particular feet, that mixtures "which contain very large amounts of acetaldehyde, for example, 0» 1 to 3 wt "parts per weight" portion of the total amount of propylene oxide and methyl formate, the invention will be handled in accordance with köimen * Virtually all of the acetaldehyde is reacted with obtained from the methyl formate and can easily be separated from it _f, for example, by simple distillation _{or the like}

When large amounts are present of methanol in the mixture of Propylenosyd and Methylforaiat} it is usually obtained flow AU3 two product "When the concentration of methanol to about 5 wt _o $ £ and preferably liögt below about 1 wt _e $ dea Sxtraktiona-Iiösungsmittela and the solvent Toluene or Kethylcycloheacan iet _s , the methanol is usually obtained for the most part in the methyl formate stream, provided that at least 60% by weight of the total oil content; which is present at all points where extractive distillation takes place, toluene or methylcyclohexane are * mixtures which contain 0.001 / »or more of methanol, based on toluene and / or methylcyclohexane feed, are treated very effectively according to the invention

BATH ORIGINAL

009829/16 6 8

The following examples explain the invention without al to restrict «

example

Starting from a mixture of 20 # methyl formate and Propylenozyd were the separations shown in the following table in an apparatus described above under Ver using the specified solvents obtain the lower boiling solvents, e.g. η-hexane, n-heptane and Cyclohexane forms azeotropic mixtures with methyl formate.

They can be used to obtain high-purity propylene oxide from methyl formate / propylene oxide mixtures however, not as satisfactory as the higher boiling solvents as they give a methyl formate product which is contaminated with solvents

Solution
Dittel Solvent
telbeschik- 00 9 8 Methyl formate
product PO * Solution
medium ^ Propyleno:
produle 99 # 8 sensational
middle
* kung, volume M'e> ^ 3
2.5 15th
30.0 Mei> 89.5 α-hexane 20: 1
10: 1 82
67.5 19th 1 - 96.8
99.7 ... -. i-heptane 10: 1 80 2.7
2.7. 15.8
15.8 10.5 99.97 . 'mm Syclohexane 11.2: 1
20: 1 81.5
81.5 17.4 ; ■ '"'" ■ ■ ■ "■ 0.6
0.3 99.7 • - ^; . «Ethyl
syclohexane 18: 1 82.6 25.7 ■■ '.? A ■': '.' ■ ". -" ,, -. ¹ yr ';. 0 * 03 - toluene 22: 1 74.3 ■? ■ · ■ "■ ■■." ■■. '' // ■■ · '' ■■ '

BATH ORIGINAL

Example 2

An extractive distillation column with 140 Oldershawglooken, with the lower 100 bells of a modified type to improve soil effectiveness, the hundredth bell (counted from below) with toluene and at the 65 * bell from below with propylenoacyd-containing Beechiokgemlsoh fed. A solution medium recovery column for the distillation of the bottoms from the first column contained 40 Olderehaw bells, the feed point at the 20. Bell lay. The operating conditions and the results are given in Table II.

Table II

Propylene oxide
Methyl formate
acetaldehyde
Methanol 1 8th 2 3 4th feed
(Weight *) feed
toluene
Reflux 79.0
21.0 56.1
16.5
27.4 55.5
43.7
0.8 57.3
18.4
24.0
0.3 etroage-
really windy
celts
(e / std) Speed .
(e / std)
Propylene oxide (weight? I)
Methyl formate
(Weight *)
Acetaldehyde (wt. #)
Methanol (wt.? S) 400
5400
1455 242
7440
1290 256
Ö430
1360 255
8520
1160 Over head-
product
from Sxtrak-
gate column speed
(g / hr)
Propylene oxide (wt. ^)
Methyl formate
(Wt / wt ppm)
acetaldehyde
(Wt / wt ppm)
Methanol
(Wt / wt ppm) 80
2.5
97.5 100
3.0
39.0
58.0 131
13.8
84.7
1.5 121
17.7
35.6
46.1
0.6 Skull
product from 0 09829/1 66 311
100
5 128
100
19th
25th 117
100
7th
<5 123
100
7th
15th
<5 telrüokge-
sensational
column

8AD ORIGi? : .v

These results show that propylene oxide is practically pure aue mixtures can be obtained which propylene oxide, Contain methyl formate, acetaldehyde and methanol. The amount of propylene oxide which goes off overhead in the extraction / distillation column can be prevented, for example, by increasing the number of trays above the feed sections or the toluene recovery geo-ability

009829/1668

BATH ORIGINAL

Claims (1)

Claims 1. A process for the production of propylene oxide, characterized in that a mixture, the propylene oxide and Contains methyl formate, extractively using a hydrocarbon solvent, which is preferably a straight-chain or branched paraffin from 5 to 10 carbon atoms, a naphthenic hydrocarbon from 6 to 8 Carbon atoms or an aromatic hydrocarbon of 6 to 8 carbon atoms is distilled. 2. The method according to claim 1, characterized in that the separation is carried out in two fractionation columns, the first column having an upper section, which is a solvent stripping section, and a lower section Section representing an extraction section has and the second column is a solvent injection column to separate the propylene oxide from the solvent «, 3ο Method according to claim 1 or 2, characterized in that the solvent used is toluene or methyloyclohexane « 4. The method according to claim 3, characterized in that that at most 5 wt <> # of methanol, based on the extraction solvent, in the propylene oxide and methyl formate SAD ORlGiNAL 009829/1668 1568036 containing Gealeoh, and at least 60% fermented liquid, which is present in all places where an extractive sea distillation takes place, toluene or Mothylovolohexane elnd 5 · Procedure according to one of the preceding tests, characterized in that the Oemleoh a large amount of Contains acetaldehyde. 6. Method according to one of the claims 1 to 3 because it is known that an oil is used "because" consists of methyl sulfate and propylene oxide " 7 · Procedure similar to one of the preceding options, which is known that the stimulant solution is underneath the distillation conditions is clearly volatile and that sttsltslioh 8ur separate supply of LöeuÄgeeittel a key portion of the extractive solvent ait that of the column ■ Oil containing propylene oxide and methyl formate is approved. MtMTAMMtH OR-IfW M FlMij »0IPl .-» i3: i S ''! ·· 4th BATH ORIGINAL 009829/1668 ^B