US2742402A - Solid caustic alkali and phenol reagent for treatment of hydrocarbons - Google Patents

Description

such as isobutyric acid, tannic alkali metal SOLID CAUSTIC ALKALI AND PI-IENOL REAGENT I FOR TREATMENT OF HY DROCARBONS Lewis M. Browning, Jr., Woodbury, N. .L, assignor to Socony Mobil Oil Company, Inc., a corporation {of New York No Drawing. Application December 26, 1951, Serial No. 263,465

4 Claims. (Cl. 196-32) The present invention relates to the treatment of hydrocarbons with solid caustic to removeweakly' acidic organic Compounds and, more particularly, to the treatment of hydrocarbons with an improved solid caustic to remove weakly acidic organic compounds,

esp ecially mercaptans.

The-problem of removing acidicorganic'materials and particularly mercaptans 'irom hydrocarbon mixturesjhas received considerable attention in'recent'years. In general, removal of mercaptans from mixtures of hydrocarbons is accomplished by extracting the mercaptans from the hydrocarbon mixture with asolution of alkali metal hydroxide. Initially, aqueous solut'ions'of sodium or potassium hydroxide were used. The extractive ability of'such aqueous solutionsywas.improved'later by the addition of organic compounds, known to the art as'solutizers, acid, naphthenic acids and alkyl phenols. fMore recently the use .ofisobutyric acid has ceased'apparently because'of its'disjappea'rance from the competitive market. On the otherhand, the use'of alkyl. phenols has probably increased due to the fact" that .alkyl phenols are present inr'nost catalytically cr'acke'd gasolines and are readily adsorbed'in or extracted by aqueous caustic solutions withwhichthe petroleum fractions are brought in contact. Generallys'peaking, aqueous caustic solutions used forthe extraction of mercap'ta'ns from admixtures with hydrocarbons, such as petroleum vfractions and particularly gasoline contaminated with mercaptans, usually contain 'an'amount of alkylphenols sufficient to neutralize about 20% to about'50% -of-the alkali metal hydroxide. The .rnaximum alkyl phenol content is limited by the viscosity'of theaqueous alkali metal hydroxide-a1kylphenolate solution and is v diiierentffor sodium hydroxide solutions and potassium hydroxide solutions of the same.phenolate concentration.

More recently, it .has been proposed that weakly organic material be removed from'mixtures with hydrocarbons with finely divided solid anhydrous alkali metal hydroxide. The use of finely divided solid anhydrous hydroxide for the removal of weakly a'cid organic material from admixture with hydrocarbons is disclosed and claimed by Kalichevsky et al. in U. siparem No. 2,311,593. These patentees disclose the use of finely divided alkali metal hydroxides for the removal of mercaptans from hydrocarbon mixtures such as petroleum fractions. Kalichevsky and his colleagues state:

Anhydrous sodium hydroxide is capable of removing quantitatively mercaptans from petroleum oils provided suflicient time is allowed for completing the reaction. With some gasolines containing higher mercaptans, from two to twenty-four hours of continuous agitation may be necessary to sweeten the gasoline, depending upon the state of sub-division of the reagent. In addition, the

the reaction and than 0.000048 centimeter. [ticles of finely divided solidanhydr'ous alkali metal hy- "erat'ion. Thus, for example,

has been lowered to apredetermined value. 7 gasoline is then separated from the finely divided send hydroxide phenolate, water-washed,

surface of the sodiumhydroxide particles is quickly coated 'Withtlie adsorbed layer of mercaptides, thus preventing further reaction. For this reason, the quantity of sodium hydroxide required to sweeten gasoline is much greater than theoretical. We'havefound that bothlthetim'eiof the quantity of sodium hydroxide required for'sweetening' gasoline depends primarilyv on the surface of sodium hydroxide'expose'd to gasoline rather than on the total quantity of sodium hydroxide present.

These patentees then state that the maximum diameter of particles of alkali metal hydroxide used for the purp'ose of removing mercaptans from gasoline containing 0.0092% mercaptan sulfur in 30 minutes should not be greater However, in general, the'pard'roxideshould beofcolloidal size, i. e., the particles should have diameters between 0.00001 centimeter and 00000001 centimeter.

The 'present invention is concerned with a finelydivided solid anhydrous'alkali metal hydroxide reagent or enhanced capability to extractwealdy acidic organic material such as mercaptans from mixtures of hydrocarbons "such aspetr'oleum fractions.

The finelykzlivided solid anhydrous alkali metal ihydroxide canbe prepared either 'bythe'methods suggested inU. S.Patent No. 2,311,593 1orbythe method described in co-pending applicationfor United States LettersiPatent No. 263,461,'fil ed December 26, 1, now U. S. "Patent 2,718,458, in the name'ofLeWis M. Browning, Jr. The finely divided solid anhydrouscaustic is then treated to incorporate a small amount of cre'sols in the particle's'of caustic. However, it is preferred to add small amounts of alkyl phenols to aqueous solutions of alkalimetal'hydroxide and'then todehydr'ate the aqueous solutionas disclosed in the aforesaid cb-p'ending application.

The finelydivided solid "anhydrous "alkali metal hy- 'dr'oxide containing not more "cresol'per pound of "MO H (where M is an alkali'inetal') calculated as NaOH (dry mixture 'of hydrocarbon than about 0.135 "poundjof basis), is contacted with .the or hydrocarbons and weakly acidic or'g'anicmaterial either i'nbatch or'continuous opgasoline can beplace'd in a container equipped with 'astirrer, and t'he partnered dosage sayzooaa of theory) of finely divided'solidan- "hydrous sodium hydroxide, containing not more than 0.135 'pound'of alkyl phenols 'per poundof sodium hyidroxide, is introduced into the gasoline'and the 'rnixture 'stirredurit il the mercaptansulfur content of the gasoline The treated anhydrous sodium 7 and sent'to storage or further treatment.

On the other hand, a column of hydrocarbon to be treated is established "and finely divided solid anhydrous oaus'tic phnolate is introduced into the/Column hearthe top thereof and withdrawn at the bottom whilst withdrawing treated hydrocarbon at the top and introducing hydrocarbon to be treated near the bottom.

The temperature of treatment is substantially that used in conventional liquid-liquid extraction of mercaptans from petroleum fractions.

Indicative of the critical limits of the concentration of alkylphenols in the particles of finely divided solid anhydrous alkali metal hydroxide necessary to produce the improved reagent are the following data obtained when treating in a single stage extraction a mixture of isooctane liquid, withdrawing said cooled particles, introducing said particles into a. petroleum fraction containing mercaptans,

and n-butyl mercaptan with 200% of the theoretical amount of NaOH except where otherwise noted.

Extraction Wt. Percent Lbs. Lbs. Wt. NaOH Na per Pgcent NaOH Percent Test Converted Lb. @2 3, Per 1,000 RSES Wt.

- to N345 NaOH Caustic lbs. (1) original 11%;; Removed ment Nae-Sodium alkyl phenolates.

(+)200% theoretical dosage.

(')-400% theoretical dosage. (l)-Oaustie dosage based upon total alkalinity of solid caustic.

Structually, the alkyl phenols have a benzene ring with an OH-group attached to one of the carbon atoms of the benzene ring with or without one or more alkyl groups attached to one or more of the remaining carbon atoms of the ring. Accordingly, the cresylic acid, or alkyl phenols or cresols, use of which is disclosed herein, contain some phenol, i. e., CeHsOH as Well as CI-IzCsI-hOH and/or higher homologues.

It is to be noted that aqueous solutions containing as much as 65 to 70 per cent alkali metal hydroxide can be used in preparing the finely divided solids, or solutions containing about to about weight per cent alkali metal hydroxide can be used. When the finely divided solid anhydrous alkali metal hydroxide is prepared from aqueous solutions containing about 20 to about 30 weight per cent alkali metal hydroxide, the particles of solid alkali metal hydroxide obtained therefrom tend to be smaller in particle size.

I claim:

1. A method of removing mercaptans from a petroleum fraction which comprises establishing a column of waterimmiscible liquid, introducing heated vapors of said water-immiscible liquid into the base of said column in an amount sufiicient to raise the temperature of said column to the boiling point of said water-immiscible liquid, introducing into said column at the upper surface thereof a plurality of fined droplets of an aqueous solution containing about 20 to about 70 per cent alkali metal hydroxide and 0.02 to about 0.135 pound of alkyl phenols per pound of alkali metal hydroxide, thereby forming a suspension of droplets of said aqueous solution in said column of water-immiscible liquid, evaporating water from said droplets thereby raising the density of said droplets as said droplets fall in said column until substantially all of the water of the droplets is evaporated and particles of a solid mixture of alkali metal hydroxide and alkali metal alkyl phenolate containing 0.02 to about 0.135 pound of alkyl phenols per pound of alkali metal and separating treated petroleum fraction from particles of a solid mixture of alkali metal hydroxide and alkali metal alkyl phenolate.

2. The method of removingmercaptans from a petroleum fraction as set forth and described in claim 1 wherein the water-immiscible liquid is a petroleum naphtha.

3. In the method of preparing a reagent for the extraction of mercaptans from hydrocarbons admixed therewith which comprises establishing a column'of water immiscible. liquid, introducing 'heated vapors of said water-immiscible liquid into said column at the base thereof in amounts sufficient to raise the temperature of said column to the boiling point of said water-immiscible liquid, introducing into said column at the upper surface thereof a plurality of fine droplets of an aqueous solution containing alkali metal hydroxide, evaporating water from said droplets as said droplets fall through said column of water-immiscible liquid until substantially all of said water is evaporated and particles of solid sodium hydroxide are formed, allowing said particles to continue to fall through said water-immiscible liquid past said point of introduction of heated vapors of said water-immiscible liquid into a cooling zone and cooling said particles of alkali metal hydroxide suspended in said water-immiscible liquid and withdrawing said cooled particles of solid alkali metal hydroxide, the improvement which comprises employing a solution of alkali metal hydroxide containing about 20 to about 70 per cent alkali metal hydroxide and 0.02 to about 0.135 pound of alkyl phenols per pound of alkali metal hydroxide.

4. The method of preparing a reagent for the extraction of mercaptans from hydrocarbons admixed therewith and set forth and described in claim 3 wherein the alkali metal hydroxide is sodium hydroxide.

' References Cited in\ the file of this patent UNITED STATES PATENTS 2,535,833 Bond Dec. 26, 1950 hydroxide are formed, allowing said particles to fall below 2 538 237 v h J 16 1951 the point of introduction of said heated vapors into a 2,574,122 Ryder Nov. 6; 1951 cooling zone containing said water-immiscible liquid, cool- 2,596,175 Rosenstein May 13, 1952 ing said particles as a suspension in said water-immiscible 2,623,008 Kleiss Dec. 23, 1952

Claims (2)

1. A METHOD OF REMOVING MERCAPTANS FROM A PETROLEUM FRACTION WHICH COMPRISES ESTABLISHING A COLUMN OF WATERIMMISCIBLE LIQUID, INTRODUCING HEATED VAPORS OF SAID WATER-IMMISCIBLE LIQUID INTO THE BASE OF SAID COLUMN IN AN AMOUNT SUFFICIENT TO RAISE THE TEMPERATURE OF SAID COLUMN TO THE BOILING POINT OF SAID WATER-IMMISCIBLE LIQUID, INTRODUCING INTO SAID COLUMN AT THE UPPER SURFACE THEREOF A PLURALITY OF FINED DROPIETS OF AN AQUEOUS SOLUTION CONTAINING ABOUT 20 TO ABOUT 70 PER CENT ALKALI METAL HYDROXIDE AND 0.02 TO ABOUT 0.135 POUND OF ALKYL PHENOL PER POUND OF ALKALI METAL HYDROXIDE, THEREBY FORMING A SUSPENSION OF DROPLETS OF SAID AQUEOUS SOLUTION IN SAID COLUMN OF WATER-IMMISCIBLE LIQUID, EVAPORATING WATER FROM SAID DROPLETS THEREBY RAISING THE DENSITY OF SAID DROPLETS AS SAID DROPLETS FALL IN SAID COLUMN UNTIL SUBSTANTIALLY ALL OF THE WATER OF THE DROPLETS IS EVAPORATED AND PARTICLES OF A SOLID MIXTURE OF ALKALI METAL HYDROXIDE AND ALKALI METAL ALKYL PHENOLATE CINTAINER 0.02 TO ABOUT 0.135 POUND OF ALKYL PHENOLS PER POUND OF ALKALI METAL HYDROXIDE ARE FORMED ALLOWING SAID PARTICLES TO FALL BELOW THE POINT OF INTRODUCTION OF SAID HEATED VAPORS INTO A COOLING ZONE CONTAINING SAID WATER-IMMISCIBLE LIQUID, COOLING SAID PARTICLES AS A SUSPENSION IN SAID WATER-IMMISCIBLE LIQUID, WITHDRAWING SAID COOLED PARTICLES, INTRODUCING SAID PARTICLES INTO A PETROLEUM FRACTION CONTAINING MERCAPTANS, AND SEPARATING TREATED PETROLEUM FRACTION FROM PARTICLES OF A SOLID MIXTURE OF ALKALI METAL HYDROXIDE AND ALKALI METAL ALKYL PHENOLATE.

3. IN THE METHOD OF PREPARING A REAGENT FOR THE EXTRACTION OF MERCAPTANS FROM HYDROCARBONS ADMIXED THEREWITH WHICH COMPRISES, ESTABLISHING A COLUMN OF WATERIMMISCIBLE LIQUID, INTRODUCING HEATED VAPORS OF SAID WATER-IMMSICIBLE LIQUID INTO SAID COLUMN AT THE BASE THEREOF IN AMOUNTS SUFFICIENT TO RAISE THE TEMPERATURE OF SAID COLUMN TO THE BOILING POINT OF SAID WATER-IMMISCIBLE LIQUID, INTRODUCING INTO SAID COLUMN AT THE UPPER SURFACE THEREOF, A PLURALITY OF FINE DROPLETS OF AN AQUEOUS SOLUTION CONTAINIG ALKALI METAL HYDROXIDE, EVAPORATING WATER FROM SAID DROPLETS AS SAID DROPLETS FALL THROUGH SAID COLUMN OF WATER-IMMISCIBLE LIQUID UNTIL SUBSTANTIALLY ALL OF SAID WATER IS EVAPORATED AND PARTICLES OF SOLID HYDROXIDE ARE FORMED, ALLOWING SAID PARTICLES TO CONTINUE TO FALL THROUGH SAID WATER-IMMISCIBLE LIQUID PAST SAID POINT OF INTRODUCTION OF HEATED VAPORS OF SAID WATER-IMMISCIBLE LIQUID INTO A COOLING ZONE AND COOLING SAID PARTICLES OF ALKALI METAL HYDROXIDE SUSPENDED IN SAID WATER-IMMISCIBLE LIQUID AND WITHDRAWING SAID COOLED PARTICLES OF SOLID ALKALI METAL HYDROXIDE THE IMPROVEMENT WHICH COMPRISES EMPLOYING A SOLUTION OF ALKALI METAL HYDROXIDE CONTAINING ABOUT 20 TO ABOUT 70 PER CENT METAL HYDROXIDE AND 0.02 TO ABOUT 0.135 POUND OF ALKALY PHENOLS PER POUND OF ALKALI METAL HYDROXIDE.