US1763722A - Process for the dehydration of impure ethyl alcohol - Google Patents

Description

June 17, 1930. E. RICARD 1,763,722

PROCESS FOR THE DEHYDRATION OF IMPURE ETHYL ALCOHOL Filed Nov. 20, 1925 4 Sheets-Sheet l ALCOHO L DEHVDRATIN COLU M N Elnvemtoz June 17, 1930. RICARD 1,763,722

PROCESS FOR THE DEHYDRATION OF IMPURE ETHYL ALCOHOL Filed Nov. 20, 1925 4 Sheets-Sheet 2 WATER A LCOHO L LIQUID MIXTURE WATER AND METHYL. ALCOHOL METHYL ALCOfi L DEHYDRATING COLUMN ABSOLUTE ALCOHOL June 17, 1930. E. RICARD 1,763,722

PROCESS FOR THE DEHYDRATION. OF IMPURE ETHYL ALCOHOL Filed NOV. 20, 1925 4 Sheets-Sheet 5 WATER WATER ETHYL ALCOHOL METHYL ALCOHOL ALCOHOL DEHYDRATING COLUMN ALCDHOL anomtoz June 17, 1930. E. RICARD PROCESS FOR THE DEHYDRATION OF IMPURE ETHYL ALCOHOL 4 Sheets-Sheet 4 Filed Nov. 20, 1925 ALCOHOL WATER mm METHYL ALCO H o L WAT E R METHY L ALCOHOL DEHYTRATI HG COLUMN ABSOLUTE ALCOHOL.

LAST-DISTILLED PRODUCTS INCLUDING ORGANIC ALKALI SALTS.

Qvwwtoz 6], m s -Z JF ullah,

Patented June 17, 19,30

UNIT-ED S TATES QPATENT OFFICEYEO ELOI RIOARD, OI." MELLE, FRANCE, AS SIGNOR, BY MESNE AS SIGNMENTS, TO U. S. 4 INDUSTRIAL ALCOHOL 00., OF NEW YORK, N. Y., A CORPORATION OF WEST VIB- vemm 1 rnocnss roa THE DEHYDRATION or IMPURE E'IHYL ALCOHOL Application filed November 20, 1925, Serial No. 70,319 and in Belgium November 20, 1924;-

ess for the dehydration of ethyl alcohol -.which is based upon azeotropic action as ordinarily employed, cannot be used when the alcohol to be treated contains certain natural or added impurities which are of 4 such nature as to gradually accumulate in the main distilling apparatus. Such impurities are prejudicial to the dehydration, and will even stop the operation altogether.

' To obviate that diificulty recourse may of' an expensive nature, whereby the im-- purities may be eliminated, but in the case of impurities which are difficult to eliminate, such as methyl alcohol, it becomes impossible to obtain the desired results. The present inventionprovides a process in which any preliminary rectification is obviated and m which the impure commercial alcohols may be dehydrated directly. 0 v The impurities considered in my said process may be of widely varyingl character, but

in general they are usually c aracterized by the following properties: They are more volatile than alcohol and they are generally soluble in water or unable to form either with water or with alcohol, taken separately, binary. mixtures having a minimum boiling point. Among the-products possessing these qualities may be mentioned acetic aldehyde, sulphuric ether, acetone, ethyl 'formate, t I methyl alcohol, and the like, which are given by way of example.

Further objects of my invention will apillustration 1 shall describe only certain ways of carrying out the same hereinafter, and have shown only certain types of apbe had to a preliminary rectifying operation,

pear from the detailed description of the paratus for use in connection therewith in theaccompanying drawings, in which- Figure 1 is a diagrammatic representation, of an apparatus used in carrying out the dehydration rocess, as set forth in my application for letters Patent, Serial No. 688,-

050, filed January 23, 1924, Patent #1,704,-

213, granted March 5, .1929, and which is utilized in carrying out my invention;

Figure 2 is a diagrammatic representation of. an apparatus which may be used in carrying out my invention showing thereon equipment which is especially adapted for accomplishing the purposes above referred to as one embodiment thereof;

} Figure 3 is a diagrammatic representation of another form ofapparatus which may be used in carrying out my invention; and

Figure 4 is a diagrammatic representation of an apparatus similar to that shown in Figure 2, but with a further addition to the same, as hereinafter described. 7

In describing my said process, I will brief- 1y mention with reference to Figure 1,'the

process for the dehydration of purified alcohol according to the practice as set forth in application Serial No. 688,050 aforesaid.

a cooling apparatus C and is discharged into a separating chamber D in which it separates into two layers. Each layer contains The alcohol of ordinary strength is fed" the three substances, water, ethyl :alcohol and an entraining liquid such as, benzol, for

example, which may be fed in by pipe a with .the alcohol. One layer, for instance the top layer, contains the major part of the entraining liquid which is returned to the column A through a conduit 12. The second layer, herein the bottom layer, is treated in a small distilling apparatus B. and B.

The apparatus B is comprised of a column provided with a steam coil T and serves to remove the whole of the entraining liquid from the liquid layer, which is supplied l thereto through a pipe d. The entraining liquid is drawn oil from the column B as a vapor mingled with a small amount of a vapor of the other two constituents of the layer and, thus, returned to the pipe a by the pipe cl. The other two constituents, comprising alcohol and water, are drawn off from the column B into the column B through a pipe h. The column B is heated by a steam coil U and serves to remove, in the form of a vapor, alcohol of a high strength through the pipe h to a condenser 11. which delivers the condensate partly to the top of the column B by a valved pipe h, but mainly by a pipe k to the dehydrating column A. The-water is discharged from the column B by an outlet pipe m. The absolute alcohol is discharged from the dehydrating column A by means of a valved outlet pipe p, which is connected to a cooler 1 having a vented outlet pipe p In the case Where an apparatus of this type is fed with an alcohol containing 5%, for example, of methyl alcohol, itwould be found that methyl alcohol has no exit from the apparatus as it does not descend to the bottom of the column to be drawn off through the pipe 1) with the absolute alcohol, nor does it pass be prevented, thus, preventing the dehydration from continuing.

Accordingly, in carrying out my invention, an outlet for methyl alcohol, when present, is provided for.

I have, thus, provided for this purpose an apparatus as shown in Figure 2. Tiis apparatus is constructed and operates in the same manner as the apparatus shown in Figure lso far as the parts disclosed in Figure 1 are found in Figure 2. In addition thereto I have-provided, however, an apparatus for carrying out the purpose above referred to. For this urpose I have provided a valved pipe 1 or drawing off from the separating chamber D a part of the decanted la er, in this instance the lower layer, in w ich the methyl alcohol is found in the greatest quantity. This is conveyed by the. pipe 1 to a distilling column 2 provided with a steam heating coil 2; The mixture therein is distilled so as to form a binary azeotropic mixture which collects at the top of the column 2 and is driven off through a pipe 2? tea condenser 3. A part of the condensate flows back through a pipe 4 to the top of the column 2 and a part is discharged through a conduit 5 into a scrubber 6 of any desired type. Water from the tank 8 is delivered through 'a valved pipe 7 to the scrubber 6. Water dissolves the methyl alcohol, thus producing a plurality of layers therein with the methy mainly in the lower layer. The upper layer containing the remaining quantity of the entraining liquid, flows away from the top of the separating chamber, thence to the pipe 4 and thence to the top of the column 2. The liquid at the lower part of the column 2 is very poor in methyl alcohol and is returned through a conduit 10 to the pipe d and thence to the distilling column B. The lower layer in the scrubber 6 is carried off by a vented pipe 11 to a distilling column 12 in which the two liquids, comprising methyl alcohol and water, are separated. The methyl alcohol is evolved from the top of the column in the form of a vapor and conveyed by a pipe 12 to a condenser 12", part of the liquid condensed being'returned by a pipe 12 to the column 12, and the remainder being carried off by a valved outlet 13. The water from the column 12 is carried away by an outlet pipe 14. For heating the column 12 there is, as shown in the drawings, a steam heating coil 14'. By carrying out the process in this manner I have obtained a continuous abstraction of the methyl alcohol, thus avoiding the accumulation of the methyl alcohol in the top of the distilling apparatus so that, as a consequence, the distilling process may be carried on continuously without any interruptlon.

Instead, if desired, I may carry out the operation in a somewhat simpler manner. In the case of not dealing with an impurity, which will tend to form a binary azeotropic mixture with the entraining liquid, the impurity in the alcohol can be made to separate directly out in the pure state at the top of the distilling apparatus. In this instance, accordingly, I am' able to eliminate the scrubber 6 and the distilling column 12. In carrying out this form of my invention I utilize an apparatus such as shown in Figure 3. The apparatus shown in this figure comprises the parts which are shown in Figure 1 but in addition thereto has certain features added to the same as hereinafter described. The lower layer from the separating chamber D containing the water,

alcohol ethyl alcohol, entraining liquid, and a large ethyl alcohol and methyl alcohol, is discharged through a conduit 28 to the distilling column B. The vapors accumulatin in the top of .the column Bare comprised mostly of the impurity or the methyl alcohol, which is condensed and discharged through a conduit 29. From the lower part of the distilling column B there is conveyed to the column B a iiiixture of water and methyl alcohol, which is distilled therein as hereinabove referred to.

In the case where, instead of one impurity the mixture contains a certain number of impurities,'the operation, in treating the same in the apparatus shown in Figures 2 and 3, would be carried out in the same manner except that the mixture of impurities to be eliminated would be discharged through the conduit 13 inFigure 2, or the .conduit 29 in Figure 3.

' In the case where the simultaneous dehydration and purification of alcohol is to be carriedout containing impurities of a widely varying character such as ethers, acids and tail products in general, I can resort to a difierent procedure as hereinafter described. My process is, thus, applicable to the treatment of raw 7 commercial alcohol or to alcohols to be again treated after havof manufacture. J In carrying out my process containing the impurities last mentioned, I may pro- .ceed as follows, for example: I neutralize the acids and saponifythe saponifiable ethers b the continuous measured addition of an al' ali such as caustic soda, caustic potash,

.ing been used as solvents in certain branches etc. at the top of the distilling apparatus and at a point below the region in which .the first distilled impurities, if any, are being eliminated, the operation bein er-- in the tail products and, accordingly, reach.

the lower part of the distilling column whence they are discharged. In case the product treated contains. acids but not ethers, I may, if desired, neutralize the acids b .the continuous measured addition of an aldiali. If the products are not neutralized they will act in the "same manner as the tail products and discharge therewith as above indicated.

I eliminate'the tail products the boiling point of which is higher than that of alco-' hol, and which consists usually of the higher alcohols, acetal, aldol, croton-aldehyde, the furfurolic bases, amines, aldeh dies of the fattyseries, the heavy ethers w ich are not saponified, the volatile fatty acids, and the like, by causing the same to descend durmg the dehydrating process, below the oint of discharge of the ethyl alcohol, wit which the said products descend in the column, as I add a certain number of plates upon which the said products will be accumulated.

The said products may be removed in the form of a liquid or vapor by means of a discharge valve, and they are then rectified in an auxiliary distilling column Where they are freed from ethyl alcohol. All of the above-mentioned last-distilled products are insoluble, or but slightly soluble,'in water, and, thus, will afiord mixtures which have a constant boiling point, and which can be distilled below 100 C. In fact, the presence of a small amount of water, which lowers the boiling point-in the rectifyin process, makes the separation of said pro ucts very difficult, but in the absence of water their boiling point remains unchanged, but this boiling point, thus will readily permit their For example, isofractional distillation. amyl alcohol will distill at 95 0. when in the presence of a small quantity of water,

and at 131 C. whenit is anhydrous. In the first instance its boiling point difi'ers from that of alcohol by only 16.5, while in the second instance it difi'ers by 53 C.

v The following example, referring to the apparatus shown in Figure 4, will exemplify the process as carried out in the form of my invention just described. The apparatus shown in Figure 4 has all of the features as shown in Figure 2 but in addition thereto I have provided an equipment for introducing the alkali and taking care of the constituents present in the treated alcohol which boil at a higher point than the absolute alcohol which is drawn off by thepipe pin the manner abovedescribed. Therefore, 1n said apparatus it will be understobd that'the apparatus abovedescribed in-detail will eliminate the acetic aldehyde, acetone and any methyl alcohol in the product. Any ethyl M acetate, which often forms the chief impurity of alcohol, has a tendency to form in the.

middle part of the column A. Through a alcohol are neutralized and the ethers L;

1 20 ing therefrom are soluble in alcohol and desaponified. The organic sodium salts resultscend to the bottom of the column A,-where they are evacuated with the last-distilled pipe 30, connected to the column A, I intro products, a number of plates A being added I for this purpose. These last-distilled prod ucts, in crude state, pass out through a pipe 32 which conveys them to a distilling column 33 steam-heated by means of tacoil 34;. The va ors from the column 33 es 34. to a condenser 35, a part of the con ensate being returned by a valved pipe 36 to the column 33, and the remainder being conveyed to the plates A through a pipe 37. The last-distilled products in concentrated state, in which are dissolved the organic alkaline salts, are extracted as a mixture from the lower end of the column 33 by means of a pipe 38, or they may be removed individually at different heights, according to their boiling points, through valved pipes 39, 40, etc. v

While I have described my invention above in detail I, wish it to be understood that many changes may be made therein .without departing from the spirit of the impurities and treating the same so as to re-- move" said lmpurities.

2. The process wh'ch comprises dehydratin aqueous ethyl alcohol containing low boiling impurities com ared with the ethyl alcohol by distilling o arr azeotropic mixture of a minimum boiling point with the aid of benzol as an entraining liquid, condensing the vapors of. the azeotropic mixture, allowing the condensate toseparate into liquid layers, decanting the layer containing the principal part of the low boiling impurities and treating the same so as to remove said impurities by distillation.

3. The process which comprises dehydrat- H ing aqueous ethyl alcohol containing low j alcoho by distilling o boilin impurities com ared with the ethyl an azeotropic mixture of a minimum boiling point with the aid of benzol as an entraining liquid, condensing the vayors of the azeotropic mixture, allowing the' condensate to separate alcohol by distilling o into liquid layers, decantin the layer containing the principal part 0% the low boiling impurities and treating the same so as to remove said impurities by distillation and washing. 4. The process whch comprises dehydrat-v ing aqueous ethyl alcohol containing low boiling impurities com aredvwith the ethyl an azeotropic mixture of a minimum boiling point with the aid of benzol as an entraining liquid, condensing the, vapors of the azeotropic mixture, allowing the condensate to separate mto hquid layers, decantin the layer contammg the principal part 0 the low boiling impurrties and treating the same so as to 'cohol from the hi remove said impurities by distillation, washin separation into liquid layers and distil ation of the'layer containing the principal part of the low boiling impurities.

5. The process which comprises dehydrating aqueous ethyl alcohol containing high boiling impurities com ared with the ethyl alcohol by distilling 0 an azeotropic mixture of a minimum boiling point with the aid of benzol as an entraining liquid while adding an alkali to the alcohol being dehydrated so as to form high boiling products by chemically combining withsaid impurities; and separatin the absolute alcohol from the hi h boiling products of the dehydration, by rawing off said products in the same distilling operation.

6. The process which comprises dehydratin aqueous ethyl alcohol containing high bolling impurities com ared with the ethyl alcohol by distilling 0 an azeotropic mixture of a minimum boiling point with the aid of benzol as an entraining liquid while adding. an'alkali to the alcohol being dehydrated, and separating the absolute alcohol from the high boiling products of the dehydration by subjecting the same to distillation by drawing off said products in the same distllling operation. 1

7 The process which comprises dehydratin aqueous ethyl alcohol containing high boiling impurities com ared with the ethyl alcohol by distilling 0 "an azeotropic mixture of a minimum boiling point with the aid of benzol as an entrainin liquid while adding an alkali to the alco 01 being dehydrated, and separating the absolute alcohol from the hi h boiling products of the dehydration by su je'ctin the same to distillation in the same distil ing 0 eration and separately drawing oif the igh boiling products and the alcohol.

8. The process which comprlses dehydratin aqueous ethyl alcohol containing low boiling and high boiling impurities com-' pared with the ethyl alcohol by distilling ofi' an azeotropic mixture of a minimum boiling point with the aid of benzol as an entraining liquid, condensing the vapors of the azeotropic mixture, allowin the condensate to separate into liquid da cantin the layer containing the principal part 0' the low boiling impurities, treating the same so as to remove said impurities while adding an alkali to the alcohol being dehydrated, and separating the absolute alboiling roducts of the dehydration by rawing o in the same distilling operation.

9. The process which comprises dehydrating aqueous eth 1 alcohol containing low boiling and hig boiling impurities compared with the ethyl alcohol by distilling ofi' an azeotropic mixture of a minimum boiling pointwith the aid of benzol as an yers, dev said products entraining liquid, condensing the vapors of the azeotropic mixture, allowing the condensate to separate into liquid layers, decanting the layer containing the principal part of the low boiling impurities, treating the same so as to remove said impurities While adding an alkali to the alcohol being dehydrated, and separating the absolute, alcohol from the high boiling products of the dehydration by subjecting the same to distillation by drawing off said products in the same distilling operation.

10. The process which comprises :de hydrating aqueous ethyl alcohol containing low boiling and high boiling impurities compared with the ethyl alcohol by distilling off an azeotropic mixture of a minimum boiling point with the aid of benzol as an entraining liquid, condensing the vapors of V the azeotropicmixture, allowing the condensate to separate into liquid layers, de-

canting the layer containing the principal part of the low boiling impurities, treating the same so as to remove said impurities while adding an alkali to the alcohol being dehydrated, and separating the absolute alcohol from the high boiling products of the dehydration by subjecting the same to distillation in the same distilling operation and separately drawing off the high boiling products and the'alcohol.

11. The process which comprises dehydrating aqueous ethyl alcohol containing low boiling and high boiling impurities compared with the ethyl alcohol by forming an azeotropic mixture of a minimum boiling point with the aid of benzol as an entraining liquid, condensing the vapors of the azeotropic mixture, allowing the condensate to separate into liquid layers, decanting the layer containing the principal part of the low boiling impurities, and treating the same so as to remove said impurities while returning the entraining liquid recovered' from said layer to the alcohol being dehydrated.

In testimony whereof I have signed this specification.

ELOI RICARD.

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