US2342386A - Process for the recovery of phenols - Google Patents

Description

Patented Feb. 22, 1944 UNITED, STATES PATENT OFFICE raooass mu m nncovaax or muons Henry G. Berger, Edwin H. Nygaard, and Henry 8. Angel, Woodbury, N. .I., assignors to Socony- Vacuum Oil Company, Incorporated, New York, N. 2., a corporation of New York No Drawing. Application December 2, 1941,

Serial No. 421,328

:rived jirom caustic treatment oi. petroleum :aactions.

As is well known to those familiar with the art, crude petroleum oils and distillate fractions obtained therefrom contain constituents other than compounds consisting only of carbon and hydrogen. Among these are compounds containing sulphur, nitrogen, oxygen, etc. Generally such oxygen compounds are represented by phenols, naphthenic acids, etc., and such sulphur compounds by mercaptans, thlophenes, disulfldes, etc. Varous methods are employed to extract these compounds irom the petroleum fractions and methods have been proposed for recovery of the phenols so removed from the mixture in which they are extracted. Usually, phenols, naphthenic acids and mercaptans'are removed from petroleum fractions containing these compounds by treatment with strong aqueous or alcoholic caustic solution. Such treatment converts phenols to phenolates, naphthenic acids to naphthenates, and mercaptans to mercaptides. Then the caustic solution containing phenolates, naphthenates and mercaptides is separated from the oil; The caustic solution is then oxidized with H202, C12, 02, etc., to convert mercaptides to disulphides, which are insoluble in the caustic solution and separate as an oil, which is withdrawn from the mixture. This procedure is unsatisfactory, however, for part of the phenols are destroyed by degradational oxidation; the undestroyed phenols remain in solution as' alkali metal phenolates in combination with the alkali metal salts of the naphthenic acids; and some disulphides remain occluded in the caustic solution. Thus, the processes proposed in the prior art do not provide for the complete removal of the sulphur compounds, and do not provide for the production of substantially pure phenols.

We have discovered a process which involves a novel sequence of operations for the recovery of phenols from the .caustic wash liquorsobtained in the caustic treatment oi petroleum fractions. By this process, phenols= substantially free of naphthenic acids and sulphur are obtained. The

process contemplated by this invention comprises the Iollowing operations: admixing the caustic wash liquor from a caustic-treated petroleum fraction with an amount of sulphur suiiicient 3 Claims. (01. zen-saw) to convert the mercaptides to disuliides and with a water-immiscible organic solvent for disulfldes; agitating this mixture and separating the caustic layer containing the phenolates and naphthes nates from the organic solvent layer containing the disulfldes, carbonating the caustic layer to convert the phenolates to phenols, and separating the carbonated caustic solution containing the naphthenates from the phenols. To eflect a more rapid and complete separation oi. the carbonated caustic solution containing the naphthe'nates from the phenols, we contemplate the modification of adding a water-immiscible organic solvent for phenols to the carbonated caus- 1 tie layer, separating the carbonated caustic solution containing the naphthenates from the sol- -vent layer containing the phenols and evaporating said solvent from the phenols. After these operations, the phenols are substantially tree of naphthenic acids and sulphur, and may be further purified by steam distillation.

We also contemplate the recovery of phenols by means of the foregoing process from acidified caustic liquors of petroleum iractions containing phenols, naphthenic acids and mercaptans. To convert the acid solution containing phenols, naphthenic acids, mercaptans and oil to a caustic solution corresponding to the original caustic solution in the aforesaid process, the following steps are taken: distilling with steam or vacuum the acid solution containing "phenols, naphthenic acids, mercaptans and oil to as low a residue as possible, discarding the residue, extracting the distillate with a water-immiscible organic solvent and extracting the solvent with a-10% caustic solution, separating the phases by withdrawing the caustic layer from the organic solvent layer containing neutral oil and organic residuum, discarding the organic solvent layer,

poses of our invention.

and treating the caustic layer according tov the liquors recovered from the caustic treatment or. I

The term "caustic liquor" used herein describes a liquor obtained'by treatment of a pe troleum fraction with an alkali hydroxide, as for example, NaOH, KOH, etc. For the purposes of economy and efliciency of operation, we have found NaOH most useful. And as aforesaid, we also contemplate the utilization of acidified caustic liquors as coming within the scope of this invention. When an acidified caustic liquor is used, it has been found that desired results are obtained when a slight excess of alkali hydroxide is used over the amount required to combine with the acidic components in the solvent layer.

Suitable solvents are those designated as water-immiscible organic solvents. Such solvents as benzene, ether, chloroform, carbon tetrachloride, etc., and low-boiling petroleum distillates, asfor example, petroleum ether are preferred.

To demonstrate the invention, the following typical example is given:

EXAMPLE An acidified spent caustic wash liquor containing a crude mixture of phenols, naphthenic acids and sulphur compounds, and represented by data given-in Tables 1 and 2, was treated as described below:

306 grams'of the crude material were steam distilled, the temperature of the distilling liquid being about 130 C. The distillate was extracted with petroleum ether and the aqueous layer ex-- tracted again with fresh petroleum ether to remove from it the bulk of the residual organic material. The combined petroleum ether extracts were now agitated with 350 cc. of sodium hydroxide. This amount of sodium hydroxide represents a slight excess over the amount required to combine with the acidic components in the petroleum ether layer. The caustic and petroleum ether layers were separated. The residue obtained by evaporating the solvent from the petroleum ether layer amounted to seven grams and was discarded; this represents neutral oil.

The sodium hydroxide layer was agitated vigorously with 600 cc. of a petroleum ether solution saturated with sulphur until a small portion of the petroleum ether layer indicates complete conversion of the sodium mercaptides to disulfides. This is evidenced by a negative doctor test by which SH-- and -S-M groups, wherein M is a metal, as. for example, Na, are shown to be absent from the solution. The sodium hydroxide and petroleum ether layers are now separated. Removal of petroleum ether from this extract yields organic disulfides.

The sodium hydroxide layer was now carbonated with carbon dioxide. The carbonation causes a separation of the phenols from the aqueous layer containing sodium naphthenates. The phenolic layer may be separated from the aqueous layer, or for a more complete separation the 5 mixture is extracted with a. water-immiscible organic solvent. For example, this carbonated mixture was extracted with 150 cc. of petroleum ether. The petroleum ether layer containing the phenols was separated and the petroleum ether steam distillation.

The aqueous sodium carbonate layer was acidified with hydrochloric acid. This causes a separation of the free naphthenic acids which can be drawn on or can be further purified by distillation.

Results of this example are summarized in Table 3 given below:

TABLE 3 Summary of data on products obtained after processing original material Per cent Grams Per cent Per cent Product isolated of total phur g g fgi,

Neutral oil 5. 0 l. 6 23.0 7. 6 21. 5 7. 1 100. 5 33. 0 Residue 62. 0 20. 3

, Represented by Loss water content- 22. 0 7. 2 By manipulation..- 72.0 23. 5

1 Includes an excess of elementary sulphur used in the conversion of sodium me'rcaptides to disulfides.

Thus, the eflicacy of our process is demonstrated by the sulphur content of the purified phenols as compared with the over-all sulphur content of the original material. As shown in Table 1,

the sulphur content of the original material is 2.72%, and in Table 3, the sulphur content of the purified phenols is only 0.2%.-

It is to be understood that theforegoing speciflc example is for illustrative purposes only and that various modifications may be made therein by those skilled in the art without departing from the scope of the appended claims.

We claim:

1. The process for the, recovery of phenols from aqueous caustic liquors containing phenolates, naphthenates and mercaptides derived from a crude caustic-treated petroleum fraction from which neutral oils have been removed, comprising the following sequence of operations: admixing said aqueous caustic liquor with a water-immiscible organic solvent for disulfides and an amount of sulphur sumcient to convert said mercaptides to disulfides; agitating this mixture and separatcrude caustic-treated petroleum fraction from which neutral oils have been removed, comprisevaporated, leaving the phenols as a residue. If 4 desired, the phenols may be further purified by ing the aqueous caustic layer containing the ing the following sequence of operations: admixin; said aqueous caustic liquor with a water-immiscible organic solvent for disulfides and an amount 01! sulphur suflicient to convert said merorganic solvent for phenols; separating the carbonated aqueous caustic solution containing the naphthenates from the. solvent layer containing the phenols; evaporating said solvent from the phenols; and purifying the phenols by steam distillation.

3. The process for the recovery of phenols from aqueous caustic liquors containing phenolates, naphthenates and mercaptides derived from a crude'caustic-treated cracked petroleum distil v 3 late from which neutral oils have been removed, comprising the following sequence of operations: admixing said aqueous caustic liquor with petroleum ether to dissolve disulfides and an amount of sulphur suflicient to convert said mercaptides to disulfldes, agitating this mixture and separating the aqueous caustic layer containing the phenolates and naphthenates from the petrole um ether layer containing the disulfides; carbonating said aqueouscaustic layer to convert the phenolates to phenols and aiding the separation of the two phases by adding petroleum ether to dissolve phenols; separating the carbonated aqueous solution containing the naphthenates from the petroleum ether layer containing the phenols; evaporating petroleum ether from the phenols; and purifying the phenols by steam distillation.

' HENRY G. BERGER.

EDWIN M. NYGAARD. HENRY S. ANGEL.

CERTIFICATE OF CORRECTION. Patent No. 2,5u2, s6. February 22, 191m.

HENRY a. BERGER, ET AL.

It is hereby certified thaterror appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 8-9, c1a;1.m'2, for "carbonating the caustic .ayer to convert [381d aqueous read -carbonating said aqueous caustic layer to convert t e"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

si ned and sealed this 9th day of May, A. D. 19%.

Leslie Frazer (seal) Acting Commissioner of Pater zts,