GB2041364A

GB2041364A - Producing Sec-butanol from Linear Butenes

Info

Publication number: GB2041364A
Application number: GB8001408A
Authority: GB
Original assignee: Anic SpA
Current assignee: Anic SpA
Priority date: 1979-01-30
Filing date: 1980-01-16
Publication date: 1980-09-10
Also published as: IT7919706A0; ES488741A0; NO800215L; DK35080A; GB2041364B; BE881437A; FR2447896A1; JPS55102530A; NL8000580A; DE3003126A1; SE8000742L; ES8103006A1; IT1110745B

Abstract

The process comprises the steps of esterifying one or more linear butene in the liquid phase with an organic acid in the presence of a cation exchange resin; hydrolyzing the resulting ester to sec-butanol in the presence of a cation exchange resin; and recovering the sec-butanol by azeotropic distillation.

Description

SPECIFICATION Process for Producing Sec-butanol from Linear Butenes This invention relates to a process for producing sec-butanol from one or more linear butenes. More particularly, but not exclusively, the present invention relates to a process for producing sec-butanol from linear butenes contained in hydrocarbon or non-hydrocarbon fractions.

It is known, for example from British Patent Specification No. 692800, that linear butenes can be directly hydrated to give sec-butanol (sometimes hereinafter abbreviated to SBA) in the presence of various catalysts (acids or Lewis acids) either in the liquid or the vapour phase.

German Offenlegungsschrift No. 1,291,729 also discloses that this reaction can also be carried out but using catalysts constituted by cation exchange resins of acid form, such as sulphonated polystyrene resins, like those known commerically by the registered Trade Marks "Dowex" and "Amberlite"; the reaction is generally carried out in the liquid phase at a temperature exceeding 1200C and in the presence of a large excess of water. However, under such conditions, the high operating temperature ultimately leads to physical decay of the resin owing to the separation of sulphonic groups from the polymer matrix, even in resins considered heat-stable in which the sulphonic groups are bonded to aliphatic chains as disclosed in United States Patent No. 2,678,332.In addition, the large excess of water in which the butene hydration is carried out results in the loss of catalytic power of the resin, and favours hydrolysis of the sulphonic groups liberated by the elevated temperature. The consequent formation of acidic substances soluble in the reaction product often makes it necessary for the effluent containing the SBA to be neutralised prior to its purification.

According to the present invention, there is provided a process for producing sec-butanol from one or more linear butene either alone or in a hydrocarbon or non-hydrocarbon fraction, wherein the one or more linear butene in the liquid phase is esterified with an organic acid in the presence of a cation exchange resin, and the resulting ester, either alone or in admixture with unreacted organic acid, is hydrolysed to secbutanol in the presence of the same or different cation exchange resin, the sec-butanol obtained being removed by azeotropic distillation.

Preferably the removal of SBA is effected continuously by azeotropic distillation.

A basis of the present invention is the surprising discovery that in double bond addition reactions, catalysis by sulphonated cation exchange resins is enhanced in anhydrous systems in the presence of acids, because of which it is possible, for example, to synthesise esters from organic acids and olefins under mild temperature conditions; also, if the ester obtained from linear butenes is suitably hydrolysed in the presence of a cation exchange resin catalyst and the formed SBA is withdrawn, the overall two stage process can be more economical than direct synthesis by hydrating the C4 stream.

According to one embodiment of the process of the present invention for producing SBA from one or more linear C4 olefin, either alone or in hydrocarbon or non-hydrocarbon fraction, the two following stages are employed: (1) the one or more linear butene is esterified in the liquid phase with an organic acid at a moderate temperature (e.g. 60--1000C) in the presence of cation exchange resin preferably of acid form, and in particular a sulphonated cation resin of acid form (for example one known in the art as Amberlyst 15, Amberlite IR-l 00, Dowex 50 W, orWolfatit C); and (2) the ester-organic acid mixture (or the ester separated by distillation) is catalytically hydrolyzed in the presence of a cation exchange resin preferably of acid form, particularly a sulphonated cation resin of acid form, operating at moderate temperature (30--1200C), with the continuous removal of the resulting SBA by azeotropic distillation with water or with waterester, and with recycling the remaining organic acid to stage 1.

The advantages of the SBA synthesis process according to the present invention derive from the resin stability, the use of only relatively small quantities of water in the ester hydrolysis, and the use of catalysts which can be easily reused over long periods.

The esterification is preferably carried out by bringing the linear butene(s) or fractions containing linear butene(s), the organic acid and the cation exchange resin into contact under agitated conditions in a heated autoclave.

Generally the temperature range of from 60 to 1 0000 is sufficient to give excellent yields. The pressure in the synthesis reactor must be sufficient to keep the butene(s) in the liquid state under the temperature conditions used; accordingly, the pressure is usually in the range from 2 to 30 atmospheres.

The molar ratio of linear butene:organic acid conveniently lies in the range from 10:1 to 1:10, although an excess of either of the two reagents can be used. Generally, a butene excess is preferable.

The organic acids which can be used for esterification are preferably selected from the C2Ca aliphatic acids, such as acetic, propionic, butyric, isobutyric, valeric, caproic and heptanoic acids.

The required reaction time depends on the temperature, and on the type and quantity of cation exchange resin used.

Preferably after separation of the catalyst by filtration or decantation, the ester-organic acid mixture formed in the ester synthesis can be processed in the subsequent hydrolysis reaction (alternatively it is possible to separate the ester by distillation), preferably after removing the butenes and other light products dissolved in it.

The ester hydrolysis is preferably carried out in a vessel surmounted by a distillation column, in the presence of a sulphonated cation exchange resin of acid form either in a stirred system, or by suitably fixing the catalyst immersed in the solution.

The water required for hydrolysis is preferably added when the temperature of the system is in the range from 300C to 1 200C, and preferably under boiling conditions by operating at or below atmospheric pressure (i.e. at from 10 to 760 mm Hg).

The SBA formed can be continuously withdrawn as the azeotrope with water or with water and ester.

The water can also be added to the system gradually. The molar ratio of water:ester is generally in the range from 0.1 :1 to 100:1, the range of 2:1 to 10:1 being preferred.

The initial reaction time before withdrawing the SBA depends on the reaction temperature, and on the quantity of water and catalyst used in the hydrolysis.

Some non-limiting examples are given hereinafter in order to illustrate the present invention in greater detail.

Example 1 A first experiment was carried out with acetic acid, Amberlyst 15 and a linear C4 stream of composition: by weight saturated C4 23.8% trans-butene-2 10.2% cis-butene-2 2.2% butene-1 60.2% isobutylene 3.6% 300 Grams (6 moles) of acetic acid, 560 g of linear C4 stream and 60 g of Amberlyst 1 5-H resin were treated in an autoclave for 10 hours at a temperature of 900C under stirring.

At the end of the reaction time, the liquid products at ambient temperature were removed by decantation from the resin analysed. The ester yield was 60%.

400 Grams of the mixture containing sec-butyl acetate (320 g, i.e. 2.76 moles) were transferred to a flask fitted with a dropping funnel and condenser and surmounted by a distillation column. 30 Grams of Amberlyst 15-H were added to the reaction solution in the flask, and the system was heated under stirring to 900C. The 60 cc (3.3 moles) of water were gradually added, and after one hour of reaction, withdrawal of SBA was begun in the form of a ternary azeotrope (b.p.760 water-SBA-sec-butyl acetate=85.5 0C). The organic phase which contained 45% SBA, 52% sec-butyl acetate and 3% water by weight, was separated from the aqueous phase and distilled under a pressure of 1100 mm Hg to give 130 g of SBA of 92% purity.

Example 2 The procedure of Example 1 was repeated except for using propionic acid instead of acetic acid, but otherwise operating under the same experimental conditions of temperature and propionic acid:butene:catalyst molar ratio.

The sec-butyl propionate was obtained with a yield of 65% after four hours of reaction.

The propionic acid and sec-butyl propionate mixture was separated from the resin and was then subjected to the hydrolysis reaction, in which 40 g of Amberlyst 1 5-H were added to the organic solution (460 g) containing sec-butyl propionate (360 g, i.e. 2.8 moles) transferred to a hydrolysis flask, and the system was raised to 950C. Then 40 cc of water were added to the solution, which was maintained at the same temperature for about two hours. Withdrawal of SBA was then begun in the form of the 87920C fraction containing water, SBA and secbutyl propionate. The organic phase was separated from the aqueous phase and rectified.

The SBA (b.p.760=99.50C) was obtained at 97.5% purity.

Amberlyst 1 5 is a styrene divinyl based resin having S03- functional groups, a porosity of 32%, a surface area of about 45 metres2/g, and an ion exchange capacity of 4.74~9 meq/g.

Claims

1. A process for producing sec-butanol from one or more linear butene either alone or in a hydrocarbon or non-hydrocarbon fraction, wherein the one or more linear butene in the liquid phase is esterified with an organic acid in the presence of a cation exchange resin, and the resulting ester, either alone or in admixturs-with unreacted organic acid, is hydrolysed to secbutanol in the presence of the same or a different cation exchange resin, the sec-butanol obtained being removed by azeotropic distillation.

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2. A process as claimed in claim 1, wherein the cation exchange resin employed in the esterification and/or hydrolysis is of acid form.

3. A process as claimed in claim 2, wherein the resin of the acid form is a sulphonated resin.

4. A process as claimed in claim 1,2 or 3, wherein the organic acid is chosen from acetic, propionic, butyric, isobutyric, valeric, caproic and heptanoic acids.

5. A process as claimed in any preceding claim, wherein the azeotropic distillation is carried out in the presence of water.

6. A process as claimed in any preceding claim, wherein the molar ratio of linear butene:organic acid is in the range from 10:1 to 1:10.

7. A process as claimed in any preceding claim, wherein the esterification and hydrolysis of the ester take place in a stirred system.

8. A process as claimed in any preceding claim, wherein the hydrolysis of the ester is carried out in a vessel surmounted by a distillation column.

9. A process as claimed in any preceding claim, wherein the hydrolysis is carried out at a pressure of from 10 to 760 mm Hg, the water being added to the boiling system.

10. A process as claimed in any preceding claim, wherein the molar ratio of water:ester in the hydrolysis stage is in the range from 0.1:1 to 100:1.

11. A process as claimed in claim 10, wherein the molar ratio of water:ester in the hydrolysis stage is in the range from 2:1 to 10:1.

12. A process as claimed in any preceding claim, wherein the temperature in the esterification stage is in the range from 600C to 100"C.

13. A process as claimed in any preceding claim, wherein the temperature in the hydrolysis stage is in the range from 300C to 1 200C.

1 4. A process according to any preceding claim, wherein the sec-butanol is removed continuously by azeotropic distillation.

1 5. A process according to claim 1, substantially as described in either of the foregoing Examples.

1 6. Sec-butanol whenever produced by a process according to any preceding claim.