US2133765A - Process for purifying naphthenic acids - Google Patents

Description

. .trol euin Iractions.; I I

It has been customary to distil the naphthenic Patented Oct. 18, 1931s I man ion;

This invention relates $6,. processfor treati g naphthenic acidsand it has particular relation Naphthenic acidsgsuch aslmight he -obtained from-the. alkali wastes arising'dnringtthe refining of petroleum orushale' oil'iractions, constitute a complex mixture of acidic compounds jcontaining principally carbon, hydrogen and oxygen.-.'They range from. comparatively low boiling liquids: to

materials which are solid2 or semi-solid at ordinarytemperatures. Their-viscosities as well as their boiling points are-directly proportional-to the viscosities and :boiling points ofthe "hydroa 1 carbon fractions in whichathey'were originally present... The crude naphthenic acids which are derived :by acidifying alkali wastes formed" during the treatment of hydrocarbon fractions contain vary- 'ing amounts of carbonaceous materials. mWhen these crude naphthenic acids are "freed from phenolic materials by careful acidification and-tdistillation as hereinafter described,...this. quantity,

of carbonaceous materials appears to increase as a-result of which 3 to 5% thereofand sometimes even greater havebeen found to be present in the dephenolized naphthenic acids. :The major portion or this carbonaceous material exists in a is not removable bysettling or centrifuging and causes the naphthenic acids to. be of a dark,

turbid color, :thereby, rendering :.their sale as a commerci'alproduet practically impossible. Y I Theterm :alkali wastes,'occurring above, is 40 meant to'include the productnwhich is obtained by treating with a caustic solutionthe extract resulting from a treatment of hydrocarbon fracacids to remove this admixed carbonaceousmaterial and then treat v the overhead product to remove the dark coloration and: foulodor there a from; This distillation was usually accompanied "by a plugging of the still due to the presence of this undesirable material and the overhead, prodx I uct was not materially improved in color-,"i.--e.,

I have discovered that these-carbonaceous terials and color bodies maybe readily/removed without distillation by contacting the crude; or r1 dephenolized acids whichiwill behereinafter des- IQ Fred crich 'rfnsisrlrm enr,- csm.-;m|smax Union Oil Company of California, Los i I I 1 perhaps, ,pentane, low boilinghydrocarbori frac tions,-. such. as I petroleum ether or' ,eleanefls .qnaphtha .(a, petroleum fraction-boiling between finely suspended: or colloidalstate', suchthat it ,4

' .benzoL- In general, ,the non-aromatic diluents mhave beenfQund-io be preferable.

- latter with ,hotair orahot inert gals. j

- a The concentr'ation Q I the a91d used in my? process should =be preerably such, that the car- 'tions with liquid sulphur dioxide as well as any other alkaline wastes arising on refining, of petainingfinorganic acids,

phosphoric ,aeid, nitric ,acid,.] etc. j' such facids are added in, small amounts to naphthenic acids containing ca'rbonaceouslmaterials and the mixture agitated for a short time, the carbona- I5 ceous materials agglomerate gto sufllciently large par-ticles to permltseparation'by settling. (H1188 furthermorebeenfound'that the naphthenlclacids thustreated. .and which haveflsubsequently been I wat r Washed and q fls tgro es y- 0 vproved color, a slightly 'higher lfacid'numberthan theuntreatedaaoids, are more fluidjand can be distilled to a 95% overhead without cokinglthe "bottoms, whereas I the untreated .ac'idsiparef lack and-opacu e,are;somewhat viscous and leavejja. 15 coke-filled residue, when distilledto .95 %gov'erhead. The aciditrea'tmentcan conveniently, and sometimes preferably be, carried out on], naphthenic, acids Iwhioh have been dilutedwith' light @hydrocarbons in which case the sludge and'carbon I20 :settlesmore rapidly,,and in some casesmore .com-

. plet e1y perhaps due to a sludge precipitating I wtendency of the 'light hydrocarbonsv in the latter instances. The light hydrocarbons-may be subsequently removed by distillation orby extraction '26 i of the naphthenic acids with alkali; Bytheterm Afl ght hyd rocarbons" I mean. any lowgboi ling :;h-ydrocarbonof either: a parafliniclor aromatic nature and it includesnormally volatile hydroe carbons, such as. propane, butane, isobutaneland 200.400 and aromatic hydrocarbons, such :as.

relates .to; ;the removal of finely 'susp'ended water from a hydrocarbon} fraction; by agitating the bonaceous material and color "bodies are] precipitated as-agran'ular mass Acids'of low concentration tend to mulsifi'iiheiiaphthenic ac'lds ,whereas. highly eoncentrated acidstend' to be ,miscibl withthe, naphtlienici l'acid's relse react "w m m. a

. Thus, where sulphurie acidlhaving a concentraernulsion, a apparently stabilized by the carbonaceous. materialj fi's obtained, These emulsions I -pre s ent considerable dimcul'ty, in" their resolution not more than could be traced'to the removal of v '55 this carbonaceous'materialitself. i

and should be avoidedlv "'I'hisemulsiQcatiQn troubleissubstantially overcome wherein'acid of 55 ,50% concentration' -or over is used; Sulphuric acid 1 of approximately 45%, strength jgave f'an emulsion which resolved jo n st'an ding for a short time. Concentrations betw en, 215% and 50% can beused under some conditions' The mostjde .oo

,tion of 4.0%orlessisfusedi'ai'Pickering type of sirable range of concentration of sulphuric acid a (or anyofr the other oxygen-containing-acids) was found to be from to approximately 83%.

Acids substantially in excess of 85% tend to bet-miscible with the naphthenic acids while some sludge separation will occur/whenv they are contacted with the latter, the treating loss becomes such that the'process is uneconom-. cu.

render them more susceptible to improvement in coloron su l nt treatment, such as distillation. V 1

.invention extends to the treatment of naphthenic acids with any oi the above identiiiedinorganic acids in thepreseh'ce of a low boiling hydrocarbon solvent whereby aniore rapid and eiilcient purification is brought about.

Although any oxygen-containing inorganic acid may for the ofmyinventionjljprefer' to use acids such as sulphuric "acid, nitric acid or phosphoric' acid as they possess avery high .degree of stability and are very easily separable from the naphthenic acids after the puriflcation has been completed. f I Therefore, more speciiicallmmy invention ex- 1 tends to the use for the purpose at out-above oi the class of ongen-containing inorganic acids of well defined concentrations (if desired in'the presence of ahydrocarbon diluent)' which conmt; or sulphuric acid, nitricacid and phosphoric I acid. I [1 a r fConsidering the. process in greater detail, a

' caustic liquor such as might be obtained'by treatingj crude kerosene or a liquid sulphur dioxide extract thereof with hydroxide is acidiiied in such a manner that it is only slightly acidic toward phenolphthalein.- By so operat- 'ing,the naphthenic acids, in contrast to the phenols, are not liberated from their alkaline Em-em saltsisodium phenomenbut remain as sodium'naphthenates; The resulting mixture of 6" sodium naphthenates, pheno s and drocarbons is then'steam distilled, if desired in gthe presenceof a srnallamount of lldeleanu extractor an'analogousliliuid-hydrocarbomsuch 'as coaltar solvent-naphtha; 'Thisextract may be the sameja'sthatfrom which the;phenols and I naphthenic acids were obtained by the above described acidification and neutralization. The

"functionof this Edeleanuextract (oritsobvious 1 equivalents) is to' prevent frbthihgduring the distillation of the mixture of. sodium naphthenates, phenols and hy rocarbon oil. The distillation of thislattermixtureywhich is preferably carried out in, the presence of steam, removes the phenols and hydrocarbon oils while the sodium naphthenates remain behind in the still. "esubstanuauy the a carbonaceous material:

which were present luv-the dephenoliaed naph- The sodium ,naphthenates remaining as a residue after distillation of the above-described mixture when dissolved, in water and treated withsulphuric'facid, produce naphthenic acids *which containonly very small amounts of phenols and admixed hydrocarbons. These crude naphthenic ".acids are of a' poor color and contain consider- I able amounts of, insoluble carbonaceous material. The maJoi-"portion of this carbonaceous material and color bodies which are present in line extract.- 2

1 materials.

process ofmyinventionz" thesecrude. naphth enic acidsin amounts varyingfrom'2, to 5%. or Tevenjhigher, exists in a.

finely suspended or colloidal state such that it is not removable by settling or centrifuging and constitutes a serious objection in the marketing -.or further "refining of the dephenollzed naphthen ic acids.

These naphthenic acids are then treated with ,;to,10"volumes per cent of an oxygenino'rganic acid of suitable concentration, for instance, sulphuric acid. The mix- .ture'is agitatedfor'a brief period of time whereupon-=the carbonaceous materials tend to agglomerate to sufliciently large particles to permit separation by settling. By adding small amounts of a "coking agent", suchas watersor siliceous @ea'rthimmediately after agitation of the naphthenic-acids with the sulphuric acid (or its equivalents) it is found that-the separation of the "sludgewhich comprises some free'sulphuric acid (or its equivalent) as well as the impurities which were present including all of the/suspended'carbonaceous material'and most of thecolor bodies, is greatly facilitated. The thus refined naphthenic acids are separatedfrom the sludge and "coking" agent and are washed with water to remove any=remaining inorganic acidity. L They are-subsequently blown bright, preferably-with an" inert gas.. A materialiimprovement in the {color and acid number is brought 'about by this treatment. Should-any-additional carbon precipitate out on staridingfiit may beremoved by cellent product having a bland odor and-a stable color offrom 2to'3 N. P. A. is,obtained.-

The separation otxthe 'sludgeand carbonaceous materials in the above described separation may be materially improved --by. diluting the impure -naphthenic acid'charge .beiore acid treatment with an equal volume of a. hydrocarbon diluent I of the nature describeduabove. In cases. where such a diluent has been employed, the latter is separated-from the sludge and carbonaceous materials together with the naphthenic acids and or byextracting the naphthenic acids with alkali and acidifying (with an inorganicacidithe" alka- As a modification or the. above-described meth-" ad of operation in which specialprecautions were cases where the presence of phenolic materials the naphthenic acidsis not'undeslrable. g f 1 The naphthenic acids, obtained'by this methtogether with od, contain in addition to the phenols which are completely soluble therewith deflnite amounts of ,r. a; v e' ov Qii e t ri a be carr outin a manner-identical to the one described in connection with the. naphthenic acids which had been substantially Thefoliowing eiramples are illustrative-.01 the may be removed. therefrom by simple distillation freed irom phenolic lmm le r a chase of 1500 cubic centimeters of semirefined naphthenic acids was air agitated for lb'minutes with 80% sulphuric acid.-. Just before theacid agitation was stopped, 5 grams of diatomaceous earth were added to facilitate the coagulation of the'sludge. The sludge (which contained only small amounts of naphthenic acids) was removed from the supernatant naphthenic, acids and the latter were washed with hot salt water; after removal of the wash water. they were blown bright with natural gas at a temperature of approximately 180 F.

The bright naphtheniciacids had anorganic distillation and a product was obtained which Acid number-297 had the following properties:

milligrams of KOH per gram of substance. l

4 Color- 2- to 2 N. P. A. Odor-Sweet.

, A distillation, similar to the one described above was made on thesemi-reflned acids before acid treatment and the following observations were made:

(1) The semi-refined acids encyto plug up the outlet oflthe still.

(2) The overhead product from the acid treat-l ed naphthenic acids was of a very much lighter ,color than that of the non-treated acids.

(3) The acid treated naphthenic acids could be distilledwithout cracking to a 97% overhead 1 (593 F. vapor temperature), while cracking occurred with thenon-acid treated acids at 92% overhead (586 F. vapor temperature). 7 g

(4) The bottoms from the acid treated naphthenie acids were still fluid when cooled; those from the untreated acids were fairly hard in consistency. l

. Example 11 'The following table illustrates at eflect of the adding of a hydrocarbon diluent and of the amount of 60% sulphuric acidpn the time necessary for sludge coagulation; v

' Time for Semil-eiined Cleaners 60% 'Agitation sludge to naphthcnic naphtha, H150 number settle to acids in ml. ml. ml. of shakes compact I mass 50 50 5 150 10 sec. 50 25 5 150 30sec. 50 i5 5 150 1 min.

50 0 5 150 15min... 50 50 4 150 30 sec. 50 50 3 150 l min. 50 50 2 150 3 min. 50 50 1 l 150 5 min. 50 0 3 150 20 min. 50 0 2 150 30 min.

This table is indicative of the fact that larger quantities of the sulphuric acid used (60%) tend to decrease the time of settling and also that an increase inthe amount of solvent for the same exhibited a tendj which they are present. l I

This invention is *not limited to any specific,

coagulation of the sludge; a i The amount of hydrocarbon diluent tcbe'used in facilitating the-separation of the coagulated.

carbonaceous material will be obvious *to those skilled in the vlilthough an amount equal 7 to that of the naphthenic acidcharge-to be treated been found practical in a number of instances, greater orlesser amounts may be necessary o'r convenient under certain conditions.

It hasbeen observed-that where the volume of w hydrocarbon diluent added is greater than that of thenaphthenic acid charge, a better color is obtained with the same amount and strengthsof acid.

Other "coking" agents than the clay,ipreviously referred to,'may be u'sed.- Thus, small'amounts *of water may beadded to the naphthenic acid mixture immediately after agitation with the sulphuric acidor its equivalents. However, "coking" agents-of the nature of clay or siliceous earth; a

are preferred as the naphthenic acids appear to have a somewhat brighter color when the nonaqueous"coking";agent' is used. 1

The distillation of the 'naphthenic acids from though this distillation will improve the color thereof, they'are' nevertheless'of 'such quality that they may be readily marketed a'commercial productil a I Although this process has-been particularly described in connection'with-naphthenicacids ad- 7 mixed-with carbonaceous m'aterialspit has been found that naphthenic acids which'are free from these materials or only substantially sc,:maybelrlateriallyimproved thereby In suchcases, the refining action brought about by this -1process seems-to reside principally in an improvement in Odor, color and acid number of'the naphthenic acids treated. 1 "*Thej naphtheni'c acids hereln described are: of'such a purity that they nlay be readily used for commercial products, such as cosmetics, soaps, emulsifying agents,- etc.

Instead of using an Edeleanu extract or, coal use any organic solvent preferably of an aromatic nature having a distillation range substantially" that of the other solvents set out above.. r I While only nitric, sulphuric and phosphoric acids have-been disclosed as examples of oxygenobtained by; the process '1 tar solvent naphtha for the prevention of frothing during distillation of the mixture OLSOdIUm 'naphthenates, phenols and hydrocarbon oil; in which process the 'phenols'are removed, I may containing "inorganicacids; it has been found that H all oxygen-containing inorganic 'acidsare capa ble ofbringingabout the purification of the naphthenic acids herein set forth. Thus, oxygencontaining inorganicacids other than those set for "the removal of carbonaceous materials or color bodies or-both from naphthenic-acids-in example herein set forth nor to'naphthenic-acids derived mm any'particular hydrocarbon fraction "containing admixed carbonaceous materials, the

"outabov'e, such as 'chloric', (H6103), bromic (Him-0:), and iodic acids (H101) may be used 25. which the carbonaceous materials havebeen removed may bedlspensedwith if so desired. 1 Alhaving a concentration between 45 and 85% and separating the naphthenic acids from the acid sludge-and the carbonaceous materials which have been agglomerated-by the aforesaidsulphuric acid. ,1: i a

2. In' a process for purifying naphthenic acids contaminated with carbonaceous materials and color bodies, thesteps of contacting said acids with sulphuric acid having a concentration of 80% and separating the naphthenic acids from the acid sludge and the carbonaceous materials and color bodies which have been agglomerated by the aforesaid sulphuric acid v 3. .Ina process for purifying naphthenic acids contaminated with carbonaceous -materials, the steps of contacting said )acids with phosphoric acid having a concentration which is in excess of and separating the naphthenicacids from the acid sludge and the carbonaceousmaterial "which hasbeen agglomerated by the aforesaid phosphoric acid. a

4. In a process. for purifying naphthenic acids contaminated-with carbonaceous .materials, the stepsof contacting said acids with anoxygencontaining, inorganic acid of such strength that .it is adapted to agglomerate theaforesaid carbonaceous materials, adding a coking agent to said mixture of naphthenic and oxygen-containing, inorganic acid and separating the naphthenic acids from the agglomerated carbonaceous materials, acid residueand coking agent. a V

:5. In aprocess for purifying. naphthenic acids contaminated with carbonaceous materials, the steps of contacting said acids with an oxygenc'ontaining', inorganic acid of such strength that it is adapted to agglomerate the aforesaid car bonaceousrnaterial, addinga coking? agent to said mixture of naphthenic acids andthe oxygencontaining, inorganic acid, separating the naphthenic acids from the agglomerated carbonaceous materials, acid residue. and coking agent, and washing the separated naphthenic acids with a reagent adapted to remove any'residual inorganic acidity therefrom. a y 1 6. Ina process for purifying ,naphthenic acids according to-clairn 5, theadditionalsteps of dis-- tillingthenaphthenic acids which are free from inorganic acidity and condensingthe overhead product.

7; A process for obtainingmaphthenic acidsof excellent color and which are free-from admixed carbonaceous materials and color bodies comprising the steps of extracting a petroleum fraction with alkali, treating the resulting extract with an inorganic acid in such a manner that; only: the phenols admixed with the; alkali naphthenates in they aforesaid extract areiliberated, distilling the phenols overhead, liberating the free crude naphthenic acids from the alkali naphthenates .re-

maining in thestill after. completion of the said distillation for'removal of the phenols by adding an inorganic acid to the'said naphthenates, sepa rating the free naphthenic acids which contain admixed carbonaceous materials, contacting said free-naphthenic acids with /2130, 10% by volume ,ofan oxygen-containing,inorganic acid of such strengththat it is adapted toagglomerate the k a 2,183,765 ms of contacting said acids with sulphuric acid aforesaid carbonaceous materials and separating the naphthenic acids from the agglomeratedcar- 'bonaceous materials and acid residues.

8. A process for obtaining'naphthenic' acids. of excellent color and free from admixed carbonaceous materials according to claim 7 in which the acid used is sulphuric acid of a concentration of more than and less than 85%.

9.*A- process for obtaining naphthenic acids of excellent color and free from admixed carbonaceous materials which comprises extractinga petroleum fraction with alkali, acid treating the resulting extract to liberate a mixture of impure -naphthenic acids, separating the impure naphthenic acids which contain the aforesaid carbonaceous-'materials, contacting the said impure naphthenic acids with an oxygen-containing, in-

organic acid selected from the class consisting of sulfuric acid, phosphoric acid and nitric acid of a concentrationbetween approximately and 83% to agglomerate the aforesaid carbonaceous materials and separating the naphthenic acids from the agglomerated carbonaceous materials and acid residue. a

10.A process for'obtaining naphthenicacids or excellent color and which are'free from admixed carbonaceous materials, comprising the steps of extracting a petroleum fraction with alkali, treatin such a manner that only the phenols admixed with the alkali naphthenates in the aforesaid extract are liberated, distilling the phenolsonly from the alkali naphthenates, liberating the free crude naphthenic acids from thealkali naphthenates remaining in the still after completion of the said distillation for removal "of the phenols by adding an inorganic acid thereto, separating the free naphthenic acids which contain admixed carbonaceous materials, diluting said acids with a low boiling hydrocarbon fraction, contacting the diluted acids with to 10% by volume'of' an oxygen-containing, inorganic acid, of such, a

strength that it is adapted to agglomerate the a aforesaid carbonaceous materials, adding a fcok: .ing agent to the acid mixture formed by contacting the diluted naphthenic acids with the aforesaid oxygen-containing; inorganic acid, separating the naphthenic acids and hydrocarbon diluent from the agglomerated carbonaceous materials, acid residue and coking agent, washing the separated naphthenic acids with a reagent -ingthe resulting extractwith an inorganic acid adapted to remove any residual inorganic acidity therefrom, separating the naphthenic acids and hydrocarbon diluent from the washing agent, distilling of! *the hydrocarbon diluent from the said naphthenates and finally distilling the naphthenic acids. a

1l. In a process for purifying naphthenic acids contaminated with carbonaceous materials. thesteps of contacting said acids with an oxygencontaining inorganic acid of the class consisting of sulphuric acid, nitric acid and phosphoric acid of a concentration between approximately 50% and 83%.

12; A method as claimed in claim 4 in which the inorganic aoid'is concentrated sulfuric acid.

FREDERICK J. EWING.