CS273000B1 - Method of methylacetate separation from its mixtures with methanol - Google Patents

Method of methylacetate separation from its mixtures with methanol Download PDF

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CS273000B1
CS273000B1 CS313888A CS313888A CS273000B1 CS 273000 B1 CS273000 B1 CS 273000B1 CS 313888 A CS313888 A CS 313888A CS 313888 A CS313888 A CS 313888A CS 273000 B1 CS273000 B1 CS 273000B1
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methanol
extractive
propanediol
methyl acetate
distillation
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CS313888A1 (en
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Jozef Ing Csc Svoboda
Stanislav Ing Harceg
Jozef Ing Tunega
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Svoboda Jozef
Stanislav Ing Harceg
Jozef Ing Tunega
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Abstract

The invention concerns a method of separating of methyl acetate from its mixtures with methanol by extractive distillation, using 1,2 propylene glycol as an extractive solvent, whereas the distillate is methyl acetate and the distillation residue, 1,2-propandiol and methanol, re-circulated back to the extractive distillation.

Description

Yywáiňz aa týká spdsobu oddeíováhia metylacetátu z jeho zmesi s metanolom extraktívnou destiláciou s 1,2-propándiolom-CpropyléngLykolom).The method relates to a method of separating methyl acetate from its mixture with methanol by extractive distillation with 1,2-propanediol-propylene glycol).

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Metylaoetát, ktorý vzniká okrem .‘ináho i ako vedlejší produkt pri hydrolýze polyvinylacetátu na polyvinylalkohol vo vodnometanolickom roztoku, je žiadaným rozpúšťadlom najma v priemysle nátěrových látok. Z reakoného roztoku sa oddeíuje destilaone vo formě zmesi s metanolom. Tieto zlóžky tvoria azeotropiokú zmes, ktorá za barometrického tlaku má obsah metylacetátupřibližné 81 % hmot. a teplotu varu 54 °C veťmi blízku teplote varu čistých zložiek, ‘najma metylacetátu (57 °C), ale i metanoluMethyl ethyl acetate, which is formed as a by-product in the hydrolysis of polyvinyl acetate to polyvinyl alcohol in aqueous methanolic solution, is a desirable solvent, particularly in the paint industry. Destilaone is separated from the reaction solution as a mixture with methanol. These compounds form an azeotropic mixture having a methyl acetate content of about 81% by weight at barometric pressure. and a boiling point of 54 ° C very close to the boiling point of the pure components, ‘in particular of methyl acetate (57 ° C), but also of methanol

64,5 °C). Za týchto okolností preto nie je možné rektifikáciou roztoku metylacetátu s metanolom izolovať vysokokoncentrovaný metylaoetát. Podobné problémy sú však i v případe, že metylaoetát bol syntetizovaný esterifikáoiou kyseliny octovéJ prebytkom metanolu. Přitom šírsiemu využitiu tejto zmesi bránia hygienické dSvody vzhťadom na vysoký obsah zdravotně závadného metanolu.64.5 ° C). Under these circumstances, it is therefore not possible to isolate high-concentration methyl acetate by rectifying the methyl acetate / methanol solution. However, there are similar problems when methyl acetate was synthesized by esterifying acetic acid with an excess of methanol. At the same time, the hygienic reasons due to the high content of harmful methanol prevent the widespread use of this mixture.

Pretože změna zloženia azeotropu metylaoetát-metanol so změnou tlaku je (podťa Ž.fiz.chim. 41.»1210 0967)) poměrně malá, nie je dostatečné efektívna separácia rektifikáciou pri dvooh rozdielnyoh tlakooh. Uvedená zmes však možno rozdělit’ špeoiálnymi destilačnými postupmi, ako sú ažeotropická destilácia napr. s chloroformom' (Ž.fiz.chim. JO, 379 (1957)), alebo extraktívna destilácia. Azeotropioká destilácia zmesi metylaoetát-metanol s ohloroformom je ovšem relativné zložitá, pretože tento systém sa vyznačuje tromi binárnymi a tiež ternárnym azeotropom. Známými rozpúšťadlami pre extraktívnu destiláciu zmesi metylacetátu s metanolom sú etylónglykol podťa USA pat. 2 636 050, etylénglykolmonoetyláter podťa NSR pat. 1 070 165, alebo voda podťa jap. pat. 1570 53.Since the change in the composition of the methyl-acetate-methanol azeotrope with the change in pressure is relatively small (according to J. Chim. 41: 1210 0967)), there is not sufficient effective separation by rectification at two different pressures. However, the mixture can be separated by special distillation processes such as an aryotropic distillation e.g. with chloroform (S.F. chim. JO, 379 (1957)), or extractive distillation. However, the azeotropic distillation of a mixture of methyl aceto-methanol with chloroform is relatively complex since this system is characterized by three binary and also ternary azeotropes. Known solvents for the extractive distillation of a mixture of methyl acetate and methanol are ethylene glycol according to U.S. Pat. 2,636,050, ethylene glycol monoethyl ether according to German Pat. 1 070 165, or water according to jap. pat. 1570 53.

Etylénglykol je v tomto případe účinné extraktivně rozúšťadlo, má však poměrně vysoké výparné teplo, čo nepriaznivo ovplyvňuje tepelné požiadavky procesu. Okrem toho je silné hygroskopioký, čo zvyšuje nároky na jeho regeneráoiu. Nevýhodou je i jeho zdravotná závadnosť. Použitie etylénglykolmonoetyléteru eliminuje sice hlavné nedostatky etylénglykolu, avšak toto extraktivně rozpúšťadlo je menej účinné a proces potom vyžaduje účinnejšiu kolonu a teda vyššie investičné nároky. Navýše je z uvažovaných extraktívnych rozpúšťadiel zo zdravotného hťadiska najnebezpečnejší. Voda je dobrá dostupná i doatatočne účinná, má však veimi vysoké výparné teplo a separácia metanolu od vody je náročnejšia ako oddelenie metanolu od etylénglykolmonoetyléteru.Ethylene glycol is an effective extractive solvent in this case, but it has a relatively high evaporation heat, which adversely affects the thermal requirements of the process. In addition, it is strong hygroscopic, which increases the demand for its regeneration. Another disadvantage is its health defect. The use of ethylene glycol monoethyl ether eliminates the major drawbacks of ethylene glycol, but this extractive solvent is less efficient and the process then requires a more efficient column and hence higher investment requirements. Moreover, it is the most dangerous of the extractive solvents to be considered. Water is readily available as well as sufficiently effective, but has a very high heat of evaporation and separation of methanol from water is more demanding than separation of methanol from ethylene glycol monoethyl ether.

Podťa tohoto vynálezu sa metylaoetát z jeho zmesi s metanolom oddeíuje extraktívnou destiláciou s 1,2-propándiolom, pričom sa odoberá ako destilát metylaoetát a ako destilačný zvyšok zmes 1,2-propándiolu a metanolu. Tento destilačný zvyšok sa može rektifikovať, s výhodou za sníženého tlaku a získaný 1,2-propándiol sa potom vedie naspat’ na extraktívnu destiláciu ako extraktivně rozpúšťadlo.According to the present invention, the methyl acetate from its mixture with methanol is separated by extractive distillation with 1,2-propanediol, taking as a distillate the methyl acetate and the distillation residue a mixture of 1,2-propanediol and methanol. This distillation residue can be rectified, preferably under reduced pressure, and the 1,2-propanediol obtained is then returned to the extractive distillation as an extractive solvent.

Výhodou sposobu separáoie metylacetátu z jeho zmesi s metanolom za přídavkuAn advantage of the method is to separate the methyl acetate from its mixture with methanol with the addition

1.2- propándiolu, ako extraktívneho rozpúšťadla, je zníženie tepelnej náročnosti procesu, okrem toho 1,2-propándiol je menej hygroskopioký a zdravotně podstatné menej závadný ako etylénglykol. Salšou výhodou je, že regenerácia 1,2-propándiolu z destilačného zvyšku extraktívnej destilácie rektifikáciou je relativné jednoduchá.1.2-propanediol, as an extractive solvent, is a reduction in the heat demand of the process; moreover, 1,2-propanediol is less hygroscopic and substantially less harmful to health than ethylene glycol. A further advantage is that the regeneration of 1,2-propanediol from the distillation residue of the extractive distillation by rectification is relatively simple.

Ako surovina sa na extraktívnu destiláciu mčže nastrekovať zmes metylacetátu s metanolom, odpadajúoa pri výrobě polyvinylalkoholu. Táto zmes može obsahovať i malé množstva ňalších látok, napr. mravčap, metylový a vodu. V tomto případe po spracovaní postupom podťa vynálezu prechádza mrávčan metylový do destilátu, avšak destilát má podstatné znížený obsah vlhkosti, pretože voda prevážne odchádza v destilačnom zvyšku extraktívnej destilácie spolu s metanolom a 1,2-propándiolom. Přitom regeneráoiuA mixture of methyl acetate and methanol can be injected as a raw material for the extractive distillation, and is dispensed with in the production of polyvinyl alcohol. This mixture may also contain small amounts of other substances, e.g. form, methyl and water. In this case, after processing according to the process of the invention, the methyl formate passes into the distillate, but the distillate has a substantially reduced moisture content since the water predominantly leaves in the distillation residue of the extractive distillation together with methanol and 1,2-propanediol. In doing so, regenerate

1.2- propándiolu možno viesť tak, že voda přejde spolu s metanolom do destilátu. Tiež zmesi metylacetátu s metanolom, vznikajúoe pri výrobě metylacetátu esterifikáoiouThe 1,2-propanediol can be conducted by passing the water together with methanol into the distillate. Also mixtures of methyl acetate with methanol are formed in the production of methyl acetate by esterification

ář kyseliny octovej nadbytkom metanolu možno spraoovať ako surovinu postupom extraktívnej destilácie s 1,2-propándiolom na jednotlivé zložky.The amount of acetic acid in excess of methanol can be treated as a raw material by extractive distillation with 1,2-propanediol to the individual components.

Extraktívnu destiláclu možno robit za atmosférického tlaku na hlavě kolony.The extractive distillate can be made at atmospheric pressure at the top of the column.

Přitom extraktivně rozpúšíadlo 1,2-propándiol sa spravidla nastrekuje blízko hlavy kolony, napr. při teplote okolia, zatiať čo surovina metylaoetát-metanol sa vaščinou privádza do dolnej polovice kolony, nďpr. zohriata na teplotu varu. Podťa zloženia suroviny a požadovanej kvality destilátu třeba upraviť veíkosť kolony, počet etáží a podmienky ako napr. nastrekované mnóžstvá suroviny a extraktívneho rozpúšťadla, polohu nástrekových etáží, refluxný poměr a přívod tepla.The extractive solvent 1,2-propanediol is usually injected near the top of the column, e.g. at ambient temperature, whilst the raw material methyloetate-methanol is fed to the bottom half of the column, e.g. heated to boiling point. Depending on the composition of the raw material and the desired quality of the distillate, the size of the column, the number of trays and the conditions such as e.g. injected quantities of raw material and extractive solvent, position of the feed trays, reflux ratio and heat supply.

Regeneráoiu 1,2-propándiolu z destilačného zvyšku extraktívnej destilácie je výhodné robit* rektifikáoiou za zníženého tlaku, čím sa využije tepelný obsah tohoto testilačného zvyšku a navýše zodpovedsjúcim znížením teploty vařáku při regeneráoii sa zamedzuje možnosti rozkladu 1,2-propándiolu. Z charakteru rovnováhy kvapalina-para systému metanol-1,2-propándiol vyplývá, že regenerácia 1,2-propándiolu je menej náročná z hťadiska potřebného počtu teoretických etáží než extraktivně destiláoia. Propylónglykol, ktorý sa odoberá z regeneračnej kolony ako destilačný zvyšok, mfiže obsahovat menšie mnóžstvá metanolu. I v tomto případe je však použitelný na reoirkuláciu do extraktívnej kolony, aj keó zvyšujúoi sa obsah metanolu v recirkulovanom 1,2-propándiole zhoršuje podmienky extraktívnej destilácie.The recovery of 1,2-propanediol from the distillation residue of the extractive distillation is advantageous to be rectified under reduced pressure, utilizing the thermal content of the test residue and, in addition, by correspondingly reducing the digester temperature during regeneration, the possibility of decomposing 1,2-propanediol is prevented. The nature of the liquid-para equilibrium of the methanol-1,2-propanediol system implies that the recovery of 1,2-propanediol is less demanding in terms of the required number of theoretical levels than extractively distilled. Propylene glycol, which is taken from the recovery column as a distillation residue, may contain minor amounts of methanol. In this case, however, it is also useful for re-circulation into the extractive column, even if the methanol content of the recirculated 1,2-propanediol increases as the conditions of the extractive distillation deteriorate.

Postup podlá tohoto vynálezu umožňuje rozdělit' na zložky azeotropiokú zmes metylaoetátu s metanolom. Rovnako úspěšně možno však týmto postupom separoval? metylaoetát a metanol zo zmesx iného zloženia ako azeotropiokého, napr. i zo zmesí s vyšším obsahom metanolu, alebo dočistit metylacetát s nižším obsahom metanolu ako zodpovedá zloženiu azeotropu.The process according to the invention makes it possible to separate the components into an azeotropic mixture of methyl acetate and methanol. Equally successfully, however, could this process be separated? methyl acetate and methanol from mixtures other than azeotropic, e.g. from mixtures with a higher methanol content, or to purify a methyl acetate with a lower methanol content than corresponds to the azeotrope composition.

Salšie podrobnosti sú zřejmé z nasledujúoioh príkladov, typických, avšak nie obmedzujúcich postup podťa vynálezu. ,Further details are apparent from the following examples, typical but not limiting of the process of the invention. .

Příklad 1Example 1

Na laboratórnom zariadení sa kontinuálnej extraktívnej destiláoii za barometrického tlaku s 1,2-propándiolom podrobila surovina obsahujúoa 64,2 % hmot. metylaoetátu,In a laboratory apparatus, a continuous extractive distillation at barometric pressure with 1,2-propanediol was subjected to a feedstock containing 64.2 wt. metylaoetátu.

34,2 % hmot. metanolu, 1,6 % hmot. metylformiátu a 0,6 % hmot. vody. Použité zariadenio sa skládalo z reaktifikačnej kolony, vařáku, destilačnej hlavy s elektromagnetickou reguláciou refluxu, piestovýoh čerpadiel suroviny a extraktívneho rozpúšťadla, zásobníkov týohto látok ako i destilátu a destilačného zvyšku. Rektifikačná kolona, vařák, hlava a zásobníky boli skleněné. Vlastná rektifikačná kolona mala vnútorný priemer 25 mm, bola naplněná kovovými Spirálami priemeru 3 mm. Celková výška náplně 132 cm bola rozdělená na tri časti, ktorých dťžka bola v smere od hlavy kolony 19,66 a 47 cm.34.2 wt. % methanol, 1.6 wt. % methylformate and 0.6 wt. water. The apparatus used consisted of a reactivation column, a digester, a distillation head with electromagnetic reflux control, a piston pump of the raw material and an extractive solvent, a reservoir of these substances as well as a distillate and a distillation residue. The rectification column, the digester, the head, and the trays were glass. The rectification column itself had an internal diameter of 25 mm and was filled with metal spirals of 3 mm diameter. The total filling height of 132 cm was divided into three sections, the length of which was 19.66 and 47 cm away from the top of the column.

Nástrek extraktívneho rozpúšťadla sa privádzal pri teplote miestnosti 24 °C medzi prvú a druhů časť, nástrek suroviny pri rovnakej teplote medzi druhů a tretiu časť kolony, Pri dávkovaní 1,2-propándiolu-599 g/h a suroviny 198 g/h za refluxného poměru 6 : 1 sa v ustálenom stave získal destilát, obsahujúci okrem metylaoetátu 2,4 % hmot. metylformiátu, 0,2 % hmot. metanolu a,0,1 % hmot. vody, pričom výťažok bol 98,6 %, počítané na čistý metylacetát. >Příklad 2The extractive solvent feed was fed at room temperature of 24 ° C between the first and second portions, the feedstock at the same temperature between the species and the third portion of the column. At 1,2-propanediol-599 g / h feed and 198 g / h feed at reflux ratio 6. In the steady state, a distillate was obtained, containing, in addition to methyl acetate, 2.4 wt. % methyl formate, 0.2 wt. % methanol, 0.1 wt. water, yield 98.6%, calculated on pure methyl acetate. > Example 2

Na podobnom laboratórnom zariadení ako v příklade 1, rozšírenom o sklenú regeneračnú kolonu 3 varákom, destilačnou hlavou a zásobníkom destilátu, sa spracovala zmes metylaoetát-metanol, obsahujúoa ..7.0,1 % hmot. metylaoetátu. Regeneračně kolona bola rovnakého priemeru a mala rovnaký typ náplně ako extraktívna kolona.In a laboratory apparatus similar to that of Example 1, expanded with a glass recovery column 3 by means of a reboiler, a distillation head and a distillate reservoir, the methyl acetate / methanol mixture was treated with 0.7% by weight. metylaoetátu. The recovery column was of the same diameter and had the same packing type as the extractive column.

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IZatial’ čo extraktívna destiláoia a 1,2-propándiolom sa uskutečnila za barometrického tlaku, regeneráoia extraktívneho rozpúšťadla sa robila za tlaku 25 kPa na hlavě regeneračnej kolony. Počet teoretických etáží vrátane kondenzátore a vařáku na extraktívnej koloně 20, na regeneráčnej koloně 7. U extraktívnej kolony sa nástrek extraktívneho rozpúšíadla privádzal do výšky 4. teoretickéj etáže, nástrek zmesi metylacetát-metanol do výšky 12. teoretickáj etáže, počítané od hlavy kolony. Nástrek destilačného zvyšku do regeneračnej kolony vstupoval vo výške 5. teoretickéj etáže, počítaná od hlavy kolony.While extractive distillation and 1,2-propanediol were carried out at barometric pressure, regeneration of the extractive solvent was performed at a pressure of 25 kPa at the top of the recovery column. Number of theoretical trays including condenser and digester on extract column 20, on regeneration column 7. In the extractive column, the feed of the extractive solvent was fed to the height of the 4th theoretical tray, the feed of the methyl acetate-methanol mixture up to the 12th theoretical tray counted from the column head. The feed of the distillation residue into the recovery column was entered at the height of the 5th theoretical tray, calculated from the column head.

V ustálenom stave pri nástreku.220 g/h suroviny o teplote 57 °C, 665 g/h extraktívneho rozpúšťadla o teplote 20 °C sa získal z extraktívnej kolony destilát, ob3ahujúci 98,9 % hmot. metylacetátu a T,1 % hmot. metanolu, pričom výťažok bol 99,4 %· Destilát z regeneračnej kolony raal zloženie 1,3 % hmot. metylacetátu, 98,7 % hmot. metylalkoholu a stopy 1,2-propándiolu. Zloženie recirkulovaného extraktívneho rozpúšťadla sa ustálilo na 0,4 % hmot. metanolu a 99,6 % hmot. propylénglykolu.At steady state at a feed of 220 g / h of feedstock at 57 ° C, 665 g / h of extractive solvent at 20 ° C, a distillate containing 98.9% by weight was obtained from the extractive column. % methyl acetate and T, 1 wt. The yield was 99.4% by weight. % methyl acetate, 98.7 wt. methyl alcohol and traces of 1,2-propanediol. The composition of the recirculated extractive solvent was stabilized at 0.4% by weight. % methanol and 99.6 wt. propylene glycol.

Claims (2)

PREDMET VYNÁLEZUOBJECT OF THE INVENTION 1. Sposob oddeíovania metylacetátu z. jeho zníesí s metanolom extraktívnou destiláciou, vyznačujúci sa tým, že sa tieto zmesi za přídavku 1,2-propándiolu ako extraktívneho rozpúšťadla rektifikujú, pričom sa odoberá ako destilát metylacetát a ako destilačný zvyšok zmes 1,2-propándiolu a-metanolu, ktorá sa áalej spracováva.1. Method of separating methyl acetate from. It is blended with methanol by extractive distillation, characterized in that these mixtures are rectified with the addition of 1,2-propanediol as an extractive solvent, taking as a distillate methyl acetate and as the distillation residue a mixture of 1,2-propanediol and methanol, which is processes. 2. Spůsob podl’a bodu 1, vyznačujúci sa tým, že sa destilačný zvyšok, t.j. zmes2. The method of claim 1, wherein the distillation residue, i. mixture 1.2- propándiolu a metanolu rekťifikuje s výhodou za zníženého tlaku a získanýThe 1,2-propanediol and methanol are preferably recombined under reduced pressure and recovered 1.2- propándiol sa vedie naspat* na extraktívnu destiláciu ako extraktivně rozpúšťadlo.The 1,2-propanediol is fed back to the extractive distillation as the extractively solvent.
CS313888A 1988-05-10 1988-05-10 Method of methylacetate separation from its mixtures with methanol CS273000B1 (en)

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