US634271A - Process of extracting acetic acid from alkaline acetates. - Google Patents

Description

N0. 634,27l. Patented Oct. 3, I899.

H PLATEB-SYBEBG. PROCESS OF EXTRAGTING ADETIO ACID FROM ALKALINE AGETATES.

(Application filed Jan. 21, 1898.)

(No Model.)

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UNITED STATES.

, PATENT Erica.

PROCESS OF EXTRACTING ACETIC ACID FROM ALKALINE ACETATES.

SPECIFICATION forming part of Letters Patent No. 634,271, dated October 3, 1899.

Application filed January 21, 1898.

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Be it known that I, HENRI PLATER-SYBERG, a subject ofthe Emperor of Russia, residing at 81 Rue de la Boetie, Paris, France, haveinvented a new Process of Extracting Acetic Acid from Alkaline Acetates, of which the following is a specification.

My invention'consists in a process for extracting acetic acid from alkaline acetates based upon the employment as primary material of the wood and mosses found in considerable quantities in the bogs or fens of Russia and Lithuania and of other analogous materials rich in carbohydrates found in abundance in nature, and hence cheap. The treatment to which I submit these materials in order to obtain acetic acid in the form of an alkaline s'alt -onsists in submitting them to the simultaneous action of a highly-concen trated alkaline lye and to that of an oxidizing agent, which may be the oxygen of the air. I thus obtain even by a cold process, but still more rapidly by a hot process, very considerable quantities of alkaline acetate.

The following is a mode of carrying out the invention: The wood, reduced to chips in order to present as large a surface for attack as possible, or the moss is thrown into the boilers containingthe highly-concentrated alkaline lye, (by preference potash lye,) and I then boil in the presence of an oxidizing agent, which may be the oxygen of the air. For this purpose the air may be continuously injected into the liquid mass. The temperature of boiling varies according to the concentration of the lye. It must not go beyond 130 centigrade if it be desired to avoid the formation of an alkaline oxalate and to obtain a maximum of acetic acid in the form of an alkaline acetate. The alkaline acetate having been thus obtained the acetic acid has next to be separated therefrom.

The usual. process hitherto for separating acetic acid from its saline combinations consists in treating the latter with a mineral acid which displaces the acetic acid,while saturating the base wherewith it is united; but this process has the inconvenience of destroying almost entirely the value of the mineral acid employed and that of the base, while forming residuals that are difficult to utilize. In order to avoid these inconveniences, I first Serial No. (567)492. (N0 specimens.)

electrolytically separate the acetic acid from the alkaline base, while contriving-to obtain the latter in the free state and the acetic acid in the form of a soluble salt. For this purpose I operatecold in an electrolytical cell, such as is represented in the accompanying drawing, which represents it in perspective and partly in section. This cell is divided by a porous diaphragm ab into two compart ments, in one of which is placed the anode c and in the other the cathode d. The porous diaphragm may be of anymaterial which fulfils the following conditions, viz: It should be capable of resisting the destructive action of the solutions employed, should offer very slight resistance to the passage of the current, and should offer sufficient resistance to the passage of the solutions in the two compartments to-prevent their mixture. The said diaphragm is represented in the drawing as formed of two perforated sheet-iron plates at, having between them a space which is filled withtightly-compressedamianthusfiberb. If the plates at be of iron, any tendency to their action as bipolar electrodes may be counteracted by coating them with a siccative solution of resin or caoutchouc. In my practice, however, with bare iron plates such tendency has been very feeble and has not manifested itself to suchcxtent as to interfere with the process.

The anode c is of iron. It is represented as composed of broken cast-iron oriron shavings or chips. yet it may be of copper. That face of the diaphragm which is next the anode-compartment of the cell, as well as the walls and bottom of said compartment, are lined with insulating material 6.

The anode solution should at the first consist of water slightly acidulated with acetic acid, to which for the purpose of diminishing the resistance there may be added a little alkaline acetate or acetate of iron, but the reaction should be always freely acid around the anode.

The cathode solution to be decomposed is of alkaline acetatepotassic acetate, for example-which may be at the first either of alkaline or neutral reaction; but after afew minutes operation this solution becomes alkaline, and its alkalinity increases as the op- The cathode may also be of iron,

eration proceeds until there remains nothing but potash lye completely deprived of acetic acid. Under these conditions after the pas sage of the current the alkaline acetate is decomposed and the acetic acid attacks the iron of the positive electrode to form ferrous acetate, while the base gathers around the negative electrode and may serve for decomposing fresh quantities of wood or moss. The reactions may be expressed by the following formulze Electrolytic decomposition:

C U O K C H O K. The anode reaction:

2(O H O )+Fe:(C II OQ Fe. The cathode reaction:

K-l-ILO KOII-l-II.

The ferrous acetate obtained as above described is pulverized in contact with the air and forms itself into ferric acetate. To this ferric acetate is added a suitable quantity of neutral acetate of potash, and I then heat till it boils. Alittle before this moment a double decomposition takes place, the neutral acetate of potash being transformed into biacetate of potash, While the iron is all precipitated in the form of hydrate of sesquioxid of iron. The biacetate of potash thus obtained is then submitted to the action of heat and separatesinto acetic acid and neutral acetate of potash, which serves to decompose fresh quantities of ferric acetate. Thus while operating in this manner the same caustic potash may theoretically serve ad mfimtum to transform wood or moss, only a certain quantity of iron has to be spent, which passes from the metallic state into that of an iron hydrate, and the necessary force for engenderingthe necessary electric current for the electrolytic operation is a relatively small matter.

I have stated above that an iron electrode has to be employed as the anode in this operation; but the iron might be replaced by another metal forming with acetic acid a soluble acetate, (such as zinc or lead, for instance.) Iron is, however, preferable not only because of its cheapness, but also because the iron'salt is more suitable for the reactions named than the salts of zinc or lead.

I claim The process for extracting acetic acid from an alkaline acetate consisting in first separating the acetic acid from the alkali by electrolysis cold in a trough provided with a positive electrode of iron or other equivalent metal and having the two electrodes separated by a porous partition, then in transforming the ferrous acetate thus formed into a ferric acetate by oxidizing with air, next in acting under the influence of heat upon this ferric acetate with neutral acetate of potash, and

finally in decomposing by heat the biacetate thus obtained into acetic acid and neutral acetate of potash, substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed my name, in presence of two witnesses, this 8th day of January, 1898.

HENRI PLATER-SYBERG.

\Vitnesses:

F. DE TCHIHA'ECHE'I, PHILIP T. RIDDET'I.

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