US2220013A - Method of obtaining naphthenic acids - Google Patents

Description

' 15 bottoms.

of crudethe stock being distilled may be de- 55, can odom- Patented Oct. 29,1940.

PATENT cm c ammo amnion or OBTAINING narnrnnmc some Johannes n. mun, swartmm, 1a., assignor to ration oi New Jersey Sun Oil Company, Philadelphia, Pa., a corpo no Drawing. Application February 5, 1936, Serial No. 62,436

I 10 Claims. (01. zen-514i The present invention relates to a process for obtaining practically pure naphthenic acids from impure 'naphthenic soap solutions or from lubricating oil still bottoms containing sodium or other alkali naphthenatesi- In the distillation oi. lubricating oils from paraihn base, mixed base, or asphaltic base crudes, where an addition of sodium hydroxideor other alkali metal base is made before or dur- 1 ing the distillatiomzsodium, or other alkali metal soaps of petroleum naphthenic or fatty acids are formed. Similarly to most inorganic sodium' salts, these soapscannot be distilled by ordinary methods and consequently may remain in the still is true regardless of what type rived from, but in the case parailln or some predominately parailin mixed base crudes the percentage of soaps will-be materially less. The

no largest amount-oi soaps will be formed in the distillation of true asphalitic crudes, a lesser percentage in r'nixed base, and a still smaller percentagein'paraflln base crudes. In fact, the recovery, of soaps from paraillnic crude residues 25 may not be important from the standpoint of soap recovery but important only as a means of Y freeing the bottoms oi soaps to render them nonemulsifiable.

If the crude is a "coastal type" asphaltic base, to and is; treated as disclosed in Pew Patent No.

1,761,153, issued June 3, 1930, the bottoms remaining after distillation will contain asphalt, some lubricating O11 otextremely high viscosity, and sodium soaps oi the acid series of the follow- :m ,llig' general formulae:

cinaqoi. 1)

65 321 100: (8land probably some the series Camps- 40:-

' these formulas the of carbon atoms,

1:, may vary from-16 to 40.

would be present the soaps oi the several acids of each series, the soaps probably being asffollows:

cans COONa. (l) Col-Ia COONa (l) Cam COONa (1) 5o Cool-Isa COQNa (2) can. COONa (2) c n COONa -(2) Cali-w 6008a (32 V Cal-In COONa' (3) v i q (3) and possibly others V asphalitic base crude.

.- someof the acids mentioned above and in addition would probably contain some acids of the series whose general formula is Oman-:02.

Thetotal acid content 01 this type crude would be somewhat less than that of a "coastal type" A paraflin basecrude, such as Pennsylvania crude, would have every low acid content, probably about .03% and would consist predominant- 137 of acids of the series whose general formulae is oilHflflofl and Conn-202.

The still bottoms, containing the sodium or other alkali metal soaps of the above mentioned petroleum naphthenic acids, may be treated in accordance with the present invention to remove these soaps, in case a paraflln base crude is being distilled, or to recover the valuable petroleum naphthenic acids corresponding thereto, in case a mixed base or asphaltic base. crude is beingdistilled.

I have discoveredthat these petroleum naphthenic acids are soluble in liquefied normally gaseous hydrocarbons, or mixtures of the same; such as propane or commercial mixtures of propane with other normally gaseous hydrocarbons, such as propylene, butane, iso-butane, and the like, while the sodium or other alkali metal soaps 01; these acids are insoluble in suohliquefled normally gaseous hydrocarbons. Certain other constituents of the still bottoms are soluble in v propane at normal or slightly elevated tempera- B6 tures, principally any heavy lubricating oil which was not distilled over-during the distillation.

Gravity Flash F 600' u Fire Fun- 695' Say. Vis. at 210 1"; seconds 575 Say. -Vis. at F, -..do 8445 about 12"parts of naphthenic acids oi'the. ty e enninemted above and about 18 parts oi'asphalt i having a melting point of about 3Q0-315'F. and containing, petroleum resins and other asphaitic impurities.

It is therefore an object of'this invention to provide a method. for obtaining practically pure petroleum naphthenic or fatty acids or their soaps from the still bottoms remaining after a crude petroleum has been distilled in the presence of an alkali.

A further object is to provide a method for producing a cutting oil from such still bottoms.

- Stillanother object is to provide a method for producing an emulsifiable road asphalt from such still bottoms.

Other and further objects will be apparent as this description progresses.

When it is desired to recover these petroleum naphthenic or fatty acids from the asphaltic still bottoms containing the sodium or other When the still bottoms have been acidified to.

the desired extent, they are then mixed with propane or some other liquefied normally gaseous hydrocarbons, such as propylene, butane, isobut-ane, and the like, or mixtures of the same.

Preferably, about 5 to volumes of propane to 1 volume of acidified still bottoms are mixed together under sumcient pressure to maintain the propane in liquid form and preferably with heating .to about 125-l30 F. The heavy lubricating oil, and also the petroleum naphthenic or fatty .acids, contained in the acidified still bottoms are readily dissolved by the propane under these conditions and ifthe mixture is allowed to stand, the propane with the lubricating oil and the petroleum naphthenic or fatty acids dissolved therein will readily separate from the asphalt. The solution of lubricating oil and petroleum naphthenic or fatty acids in propane is then withdrawn from the asphaltic residuum.

Since these petroleum naphthenic or fatty acids are frequently'used in the form of their corresponding soaps in admixture with lubricating oils as a cutting oil, the propane may be distilled off from the solution of lubricating oil, naphthenicor fatty acids and propane, and the solution of naphthenic or, fatty acids and oil thus obtained may be saponified in any known manner, as by the addition of an alkali metal basesuchas NaOH, to convert the naphthenic or fatty acids contained in the lubricating oil into their corresponding alkali metal'soaps. Additional lubricating oil may then be added to this mixture of soaps and oil to form a cutting oil compound, or the mixture of soaps and oil itself may be used as a cutting oil. --However, as pointed out above, the

heavy oil recovered from the still bottoms is quite valuable and .is a type which heretofore has not been recovered. It may therefore be desirable to recover this oil freeof thepetroleum naphthenic or fatty acids or their soaps and mix a cheaper grade of oil with the soaps of the petroleum naphthenic or fatty acids to form a cutting 011',

If it is desired to recover this heavy lubricating oil free of the petroleum naphthenic or fatty naphthenic or fatty acid soaps and oil. Under these conditions the heavy lubricating oil is readily dissolved by the propane while the petroleum naphthenic or fatty acid soaps are not. The solution of lubricating oil in propane may readily be separated from the soaps, as by allowing the mixture to stand to permit the soaps to settle out and then drawing oil the solution of propane and oil separately from the soaps.

A slight modification of the process described above, for recovering the lubricating oil free of the petroleum naphthenic or fatty acids or their soaps, is to take the solution of lubricating oil and petroleum naphthenic or fatty acids in propane obtained from the still bottoms by the propane extraction first described above and saponifying the petroleum naphthenic or fatty acids in propane in an amount sufficient to convert the petroleum naphthenic or fatty acids into their corresponding soaps. Since the petroleum naphthenic or fatty acid soaps are not soluble in propane, they will be precipitated and the solution of lubricating oil and propane may be separated from the soaps in any desired manner as permitting the mixture to stand and drawing off the solution of lubricating oil and propane after the soaps have settled out. The propane may then be separated from the heavy lubricating oil by distillation, thus yielding a heavy lubricating oil having the characteristics described above. While the alkali metal soaps of the petroleum naphthenic or fatty acids thus obtained will be of the type heretofore described and may be used for any desired purpose as by mixing them with lubricating oil to form a cutting oil, or other soluble or emulsifiable oil. The soaps if again acidifled have a saponification value of 80-160 mg. of KOH per gram.

At times itmay be desirable to recover an asphalt containing a small percentage of soaps of the petroleum naphthenic'or fatty acid soaps, as when it is desired to produce an emulsifiable road asphalt. In such case the still bottoms may be acidified by mixing with them such an amount of mineral acid that only a portion of the soaps contained therein will be converted into the corresponding naphthenic petroleum or fatty acids and a sufilcient amount of the petroleum naphthenic or fatty acids will remain in the form of their alkali metal soaps so that when the acidified still bottoms are mixed with propane and the heavy lubricating oil and petroleum naphthenic or fatty acids thus extracted from the asphaltic constituents, as described heretofore, the asphalt so recovered will contain the desired percentage of soaps for making an. emulsifiable road asphalt. The amount of soaps left in the asphalt will, of course, depend on the specifioa-.

tions for the road emulsion'and on whether the asphalt so recovered is to be used aloneor mixed with other o'ilsand/or asphalts.

While I, have described, my process in connection. with.obtaininghaphthenic acids from the still bottomsremaining after a lubricating oil has been distilledin the-presence of an alkali metal base, it isapparent that my process may be used for purifying naphthenic acids which 7 is separated from the asphalt.

have been recovered from the still bottoms by some other method, for instance by thev "pressure settling" method described in Angstadt Patent No. 1,931,880. In fact, it should'beiunderstood that the production of such stillbottoms, being incidental to the distillation of lubricating oils in the presence of an alkali metal base, is merely one, and perhaps the simplest, way of, obtaining the starting-material to which I apply my process. The-starting material may be obtained in any other way. For example, in the process set forth in my hereinafter mentioned application, of which this application is a division, suitable starting material is obtained by mixing such still bottoms with propane to dis-. solve the heavy lubricating oil that is contained in the still bottoms, and separating-the, solution of propane and oil from the mixture of asphalt and soaps, which affords a suitable starting material. As described in the specification of said application, and in this specification, the mixture ls-then acidified to break down the soaps to form naphthenic and fatty acids, liquid propane oranother normally gaseous hydrocarbon is added to dissolve the acids, and the solution naphthenic acids, or the soaps of theseacids o of ,80 to 180 mg. ofKOI-I per gram and are most when again acidified, have a saponification value suitable for use in the form 'of their corresponding soaps in preparing soluble oils and oil emulsions of all kinds.

While I have particularly mentioned propane in the above description of my process, it is to be understood that otherliquefiednormally gaseous hydrocarbons such as ethane, ethylene, propylene, butane, loo-butane, and the like or mixtures of the same, with or without propane, may be used instead of propane, and where the term liquefied: normally gaseous hydrocarbon" isused in the appended claims it isv to be understood as including. such compounds and mixtures. I

This application is a continuation-in-part of my copending application'Serial No. 16,607, filed April 16, 1935. I

, What I claim and desire to protect by Letters Patent is as follows:

1.. The method of separating the soaps of petroleum naphthenic and fatty acids from a mixture-of the same with asphaltfsuch as is pro-- duced as still bottoms from the distillation'ofpetroleum in the presence of an alkali metal base, which comprises acidifying said mixture, to break down'said metal soaps of said petroleum naphthenic and fatty acids to formthe cor- "responding petroleum naphthetic and fatty acids,

mixing said acidified mixture with a liquefied normally gaseous hydrocarbon to dissolve said petroleum naphthenic and fatty acids and separating saidliquefied normally gaseous hydrocarbon with said petroleum naphthenic andjatty acids dissolved therein from said asphalt.

, 2. The method 'of making'a cutting oil from a mixture of the soaps of petroleum naphthenic and fatty acids' with heavy lubricating oil and asphalt, such as is produced as still bottoms re-- maining afterthe'distillat'ion ,of a crude petroleum in the presence of an aikali'metal which comprises acidifying said mixture to convert the said soaps intotheir corresponding pe troleum naphthenic and fatty acids, mixing the thuslacidifiedmiixture with a liquefied normally gaseoushydrocarbonto dissolve said heavy lu-* bricatingpoil and saidpetroleum naphthenic and The purified fatty acids, separating said liquefied normally gaseous hydrocarbon with said heavy lubricating oil and said petroleum naphthenic and fatty acids dissolved therein from the asphalt, and removing said liquefied normally gaseous hydrocarbon from said heavy lubricating oil and said petroleum naphthenic and fatty acids and saponifying said solution of heavy lubricating oil and said petroleum naphthenic and fatty acids to convert said petroleum naphthenic and fatty acids into their corresponding soaps.

3. The method of making a cutting oil from a mixture of the metal soaps of petroleum naphe thenic and fatty acids with heavy lubricating oil and asphalt, such as is contained in asphaltlc still bottoms remaining after the distillation ofa crude petroleum in the presence of an alkali metal base, which comprises. acidifying said mixture to convert the said soaps into their corresponding petroleum naphthenic and fatty acids,

mixing the thus acidified mixture with a liquefied normally gaseous hydrocarbon to dissolve said heavy lubricating oil and said petroleum naphthenic and fatty acids, separating the said liquefied normally gaseous hydrocarbon with said heavy lubricating oil and said petroleum naphthenic and fatty acids dissolved therein from the asphalt, removing said liquefied normally gaseous hydrocarbon from said heavy lubricating oil and said petroleum naphthenic and fatty acids and saponifying said solution of heavy-lubricating oil and said petroleum naphthenic and fatty acids to convert said petroleum naphthenic and fatty acids into their corresponding soaps and adding lubricating oil to the mixture of heavy lubricating oil and soaps'to form a cut- 4. The method of recovering petroleum'naph thenic and fatty acid soaps from a mixture of the same with heavy lubricating oil and asphalt,

such as is produced as still bottoms remaining after the distillation of a crude petroleum in the presence of an alkali metal base, which comprises acidifying 'said mixture to convert the said soaps thenic and fatty acids to convert said petroleum naphthenic and fatty acids into their corresponding soaps,,mix'ing the mixture of heavy lubricating oil and soaps then formed with a'liquefied normally gaseous hydrocarbon to dissolve said heavy lubricating oil and precipitate said soaps, and separating s'aid liquefied normally gaseous hydrocarbons with said heavy lubricating oil dissolved therein from said petroleumnaphthenic and fatty acid soaps.

. 5. The method of recovering petroleum naphthenic and fatty acid soaps from a mixture of the I same with heavy lubricating oil and asphalt, such as is produced as still bottoms remaining after the distillation of a crude petroleum in the presence of an alkali metal base, which comprises acidifying said mixture tdconvert the said soap! into their correspondingpet nle'umnaphthenim and fatty acids, mixing the thus acidified mixture with a liquefied normally gaseous hydrocarbon to dissolve said heavy lubricating oil and said petroleum naphthenic and fatty acids, separating said liquefied normally gaseous hydrocarbon with said heavy lubricating oil and said .petroleum naphthenic and fatty acids dissolved therein from the asphalt, saponifying said solution of heavy lubricating oil and petroleum naphthenic and fatty acids in said liquefied normally gaseous hydrocarbons to convert said petroleum naphthenic and fatty acids into their corresponding soaps and separating said liquefied normally gaseous hydrocarbon with said heavy lubricating oil dissolved therein from the thus precipitated petroleum naphthenic and fatty acid soaps.

6. The method of making an asphaltic road emulsion and a cutting oil from a mixture of naphthenic and fatty acid soaps with heavy lubricating oil and asphalt such as is contained in the asphaltic still bottoms remaining after distilling a crude petroleum in the presence of an alkali metal base, which comprises adding a mineral acid to said. mixture in an amount sufficient to convert a part of said soaps into their corresponding petroleum naphthenic and fatty acids, mixing a liquefied normally gaseous hydrocarbon with said partly acidified mixture to dissolve said heavy lubricating oil and said petroleum naphthenic and fatty acids, separating said liquefied normally gaseous hydrocarbons with said heavy lubricating oil and said petroleum naphthenic andfatty acids dissolved therein from a residue of asphalt and petroleum naphthenic and fatty acid soaps suitable for a road emulsion, removing said liquefied normally gaseous hydrocarbons from said heavy lubricating oil and said petroleumnaphthenic and fatty acids, and saponifying said solution of heavy lubricating oil and petroleum naphthenic and fatty, acids to convert said acids into their corresponding soaps and thus form a cutting oil. 7.

7. The method of recovering the soaps of petroleum naphthenic and fatty acids from a crude starting material which contains such soaps in admixture with heavy lubricating oil, asphalt, petroleum resins, and other asphaltic impurities, which comprises acidifying said starting material to convert said soaps into their corresponding petroleum naphthenic and fatty acids, mixing the thus acidified starting material with a liquefied normally gaseous hydrocarbon to dissolve said 'heavylubricating oil and said petroleum naphthenic and fatty acids, separating said liquefied normally gaseous hydrocarbon with said heavy- 7 phalt, removing said liquefied normally gaseous hydrocarbon from said. heavy lubricating oil and said petroleum naphthenic and fatty acids, saponifying said solution of heavy lubricating oil and said petroleum naphthenic and fatty acids to convert said petroleum naphthenic and fatty acids into their corresponding soaps, mixing the mixture of heavy lubr' ting oil and soaps then formed with a liquefie normally gaseous hydrocarbon to dissolve said heavy lubricating oil and j precipitate said soaps, and separating said liquefied normally gaseous hydrocarbons with said heavy lubricating oil dissolved therein from said petroleum naphthenic and fatty acid soaps.

8. The method of recovering the soaps of petroleum naphthenic and fatty acids from a crude starting material which contains such soaps in admixture with heavy lubricating oil, asphalt, petroleum resins, and other asphaltic impurities, which comprises acidifying said starting material to convert said soaps into their corresponding petroleum naphthenic and fatty acids, mixing the thus acidified starting material with a liquefied normally gaseous hydrocarbon to dissolve said heavy lubricating oil and said petroleum naphthenic and fatty acids, separating said'liquefied normally gaseous hydrocarbon with said heavy \lubricating oil and said petroleum naphthenic and fatty acids dissolved therein from the asphalt, saponifying said solution of heavy lubricating oil and petroleum naphthenic and fatty acids in said liquefied normally gaseous hydrocarbons to convert said petroleum naphthenic and fatty acids into their corresponding soaps and separating said liquefied normally gaseous hydrocarbon with said heavy lubricating oil dissolved therein from the thus precipitated petroleum naphthenic and fatty acid soaps.

9. A method of purifying crude naphthenic acids derived from petroleum, shale oil, coal tar and like fractions which comprises commingling said acids with a liquefied normally gaseous hydrocarbon solvent to dissolve the naphthenic acids but not the impurities present therein and separating the solution of naphthenic acids dissolved in said solvent from the undissolved impurities.

10. A method of purifying naphthenic acids containing asphalt-like substances which comprises commingling said acids with a-liquefied normally gaseous hydrocarbon to dissolve the naphthenic acids and to precipitate said asphaltlike substance and separating the solutiorr of naphthenic acids dissolved in the liquefied normally gaseous hydrocarbon from the precipitated asphalt-like substances.

JOHANN'ES H. BRUUN.