US2190471A - Refining of petroleum distillates - Google Patents

Description

25 saturation.

I PsteniedFeb- 1 1940' 1' I I r 2,190,471;

UNITED {STATES PATENT OFFICE anion 11,

RErmrNo oFrE'moLEUM DISTILLATES- Carleton Ellis, Montclair N. J assignor to Standard Oil Development Company,a corporation of Delaware I N0 Drawing. ApplicationAugust 26, 1938, SerialtNo. 226,905 J i 5 Claims (01,. 196-44 This invention relates to the refining of petroacidiis feasible in someecases. It is generally leum distillates and in particular to those distilter when more concentrated sulphuric acid, say lates resultingtfrom the pyrolysis or cracking of 98'per cent, is the refining agent that simultane highi-boiling petroleum fractions. It is espe ously some type of cooling means be used. For

5 cially applicable to'refining gasolines which have example, the distillate and sulphuric acid may be 5 been made :by cra king operations and which mixed in an agitator equipped with a coil through v have been subjected to treatment with sulphuric which is circulated a cold solution of brine or acid- 1 v f i i calcium chloride." Afterwards, the mixture is Cracked distillates, made by pyrolysis of crude transferred to a settlingtank where stratification l petroleum or any of itsvarious fractions, coninto two layers occurs. The lower, or acid, layer i=0 tain a relatively large proportion of. olefinic bodis withdrawn and'the upper, or hydrocarbon, layies. The latter may constitute as much as 20, er then washed (in the same or anothertank) 30 or 40 per cent by volume, or even higher, of successively with water, dilute aqueous alkaliand the liquid product. The exact proportion will again with water. By'distillation of the treated I varyconsiderably depending, to a large, extent distillate the desired'fraction', or-fractionsyof reupon the temperature'and pressure em'ployed fined hydrocarbons'is secured. during the cracking. operation and also whether The application of sulphuric acid as a refining I or 'nota catalyst (or catalysts) is used. Generagent. (as described above) results, amongiother; ally speaking, the higher the temperature, the effects, in the elimination of'a substantial.propor-,

lower the pressure, and the presence of one or tion' of deleterious sulphur-containing com- 20 more catalysts are the factors which' favor the pounds, gumor resin-forming olefins or unsatformation of larger quantities ofoleflns or unurated hydrocarbons,and color' developing bodies. saturated hydrocarbons in the resulting distil- However, at" the same time there is formed a cerlate or, in other words, a greater-degree of untain proportion of alkylsulphuric acids and dial:

. 1 kyl sulphates due to interaction ofthe acidwith I Some of the olefinic hydrocarbons may be unolefinic hydrocarbons in the .oilundergoing treatsaturated to such a degree as to giverise to gummerit. Both types of'these sulphuric acid derivae my or resinous compounds when the distillate is tives, are soluble, to a very substantial extent, in stored forappreciable periods oftime. Such a 1 the distillate undergoing the refining operation.

30, condition-is undesirable, particularly when the The-alkylsulphuric acids may be re'movedqto a as; liquid hydrocarbons are to be employerl'as gaso- -'considerable degree by the alkali and water line or fuel for internal combustion engines. In washes giventhe acid-treated distillate. Simu1- addition, certain types of cracked distillates postaneously, some of the dialkyl sulphates may be; sess a relatively high content of sulphur-.containeliminated as these maybe hydrolyzed, at least in ing'compounds. In some instances the'latter may part, by the alkali and water washes to a1kylsul- 35 act as accelerators of gumor resin form'ation, phuric acids and alcohols, and both ofthe latter may effect undue corrosion, for example, of the (particularlythe alkylsulphuric acidsldissolved metalcontainers or the engine parts withwhich to some extentin the aqueous layers. Neverthey come in contact, or may adversely affect the theless a substantial "proportion of dialkyl sul 40 action of lead tetraethyl or other antiknock .phates (and possibly some alkylsulphuric acids) 4(] 1 agents when such agents are blended with the remain dissolved in the hydrocarbon material.

gasoline or;-other fractions. Also,.l0wer-boiling This is particularly disadvantageous since on fractions resulting from the pyrolysis of crude distilling the hydrocarbons there is considerable e petroleum or its various fractions usually contain decomposition ,of such sulphu rrcontaining com- '45v color-forming bodiesto, a greater or lesser extent. 1 j pounds accompanied by the development of acidic,

The removal, atleast inpart, 0f gumor resinbodies, e. g., sulphur dioxide. .The presenceof forming olefins, of sulphur-containing) comthe latter is highly undesirable. Being acidic in pounds, and of color-forming bodies constitutes" character it may effect much corrosion, for exe m bie f efinin operations: amp-1e, of the metal parts of the still during the method f fi in ll te particularlydistillation operation, This is;especially true if 50 those boiling within the ga'solirieand kerosene some steam is employed (as is done in many inn c0mplises treatment W Su p acidstahcesl as an aid to distillation, since sulphurv In most instances,'acid of about 93'p erv cent condioxide reacts with .water to furnish sulphurous 'centration or thereabouts'is employed, though aCidQahighIy corrosive substance. Furthermore the use of more concentrated or less concentrated, ifsulphur dioxide remains dissolved for any ap-F 55;

. gums or resins takes'place. v Decomposition of dialkyl sulphates to sulphur preoiable period of time in the fraction secured on distillation (especially if oleflns are present therein) the liquid becomes badly discolored and considerable formation of soluble sulphur compound not only is acidic and corrosive in character but also extremely toxic. I propose to decrease or suppress to a very substantial extent this development and evolution of sulphur dioxide and/or other acid bodies by' interaction of dialkyl sulphates (dissolved in the acid-treated distillates) with heavymetal saltsof phenolic bodies. Examples of the latter which are suitable for my purpose are phenol (carbolic acid) and cresols. Preferably those metals are employed whichform hydrocarbon-soluble derivatives with the phenolic bodies. An illustration ofaacompound suitable for my-purpose. is lead phenolate made by reaction of lead oxide with phenol. I I 1 .Solutions of themetallic salts of phenolic bodies mayJ-be' prepared in any convenient manner. For example, phenol (carbolic acid) may be admixed with a portion of gasoline-and as the mixture is kept stirred there. is added, in small portions,

a quantity of lead oxide which is slightly in excess of that required to react with the phenol. After reaction is'complete'the excess oxide can be separated from the-solution. of. metallic phenolate by'filtration or decantation. I In other instances interaction may be 'eifected by heating a mixture of metallic oxide and phenolic compound, e. g., mercuric oxide and .cresol. After-v wards the reaction product is extracted with .a hydrocarbon: solvent; say benzoLto secure a solution of the phenol derivative. i

. One procedure whereby I may carry out my invention is as follows! A sample of cracked distillate, which had been treated with sulphuric acid and then washed with aqueous alkali and with water, was added. to aqueous alcohols'and the solution at room temperature immediately titrated with a standard solution of..alka1i. This furnished an indication of the combinedproportionsof alkyl-sulphuric acids and'readilyhydrollyzable dialkyl sulphates in the distillate. The alcoholic solution is then heated under reflux to effect hydrolysis of the dialkyl sulphates to sulphuric acid, after which'the illlXllllZ'E'lS cooled and again titrated with alkali. This last titration is, therefore, a measure of the quantity of dialkyl esters of sulphuric acid. From these two titrations may be calculated the quantity of metallicphenolate necessary to react with-the sulphuric acid -'.derivatives dissolved in the dis tillate.

The acid-treated distillate is then blended with.

the requisite volume of hydrocarbon solution of metallic phenolate. After some time a precipitategpresmhably the metallic sulphate, slowly,

then be removed by filtrathe supernatant liquid, or means. If desired, interac-- settles outand may tion, decantationof any other convenient tion maybe hastened by gently warming the reac- 1 tion mixture though this .is not necessary to secure good results. Distillation of the filtered or clear distillate can be efiected to obtain any y desiredfraction as a product.

and insoluble I passed through. an aqueous solution :of alkalir" it contained 10.0371 gram stantial degree of solubility. Preferably, however, the solvent should boil within the temperat to yield gasolinathe dissolved in a portion treated distillate is distilled metallic phenolate maybe ture range correspondingto that of the desired petroleum fraction. For example,if..the acid-,

of refined gasoline'or benzol ortoluol Orin mixtures of these.

- the refined an'd distilled product. However, Ido ,not'limit'myself tothe solvents justmentioned as many otherfliquids in which the metallic .If the liquid; medium is of the type and character 'of the petroleum distil 10 source of any new or unusual compound phenolates are soluble and which are miscible also with the hydrocarbon distillate at hand may be employed. The following examples will serve as specific illustrations.

Example .1.Aqueous isopropyl alcohol.

cc.) was added to acid-treatedtoracked distillate. i (50 cc.) and the mixture immediately titrated with standard (0.09446N) alkali. This required 0.89 cc. ofalkali solution. The alcoholic mixture hydrolysis of 'dialkyl' sulphates) and after? cool-7" oxide (over that required to reactwith the phenol) in small portions. I "had stood forseveral hours, with occasional-shake After the 'mixture was removed. by filfound that the lead ing, all undissolved' material tration.- Onzahalysis it -was again titrated;

phenolate content'of the solution wassequivalent to 0.077 gramioflead perlO cc. From the-above alkali titrations it was estimated that' :40 volumes. of the lead phenolate solution were {required for '450 volumes. of the acid-treated distillate. When the two liquids were mixed 'inxthisZ'proportion and allowed to stand for several hours, a white precipitate;presumably lead sulphate, slowly settled out. This was'removedby filtration and the clear liquid" distilled, taking'over that portion boiling up to F. During 'distillation'all evolved gases were After distillation wasicompletethe liquid product was Washed centration .ofv ralkali in the solution was determined before and afterit was employed as do scribed. In this'manner it was noted that the. total'acidity developed (gaseous plus that dis solved in the liquid product and sulphuric acid) was equal to 0.018 percent.

Another sample. of the same acid-treated dish v tillate, without prior addition of lead phenolate,

Wasdistilled in like manner.

0.038 per cent.

mixture of meta oxide were added to with the same solution. .The'con The total acidity which developed in thisinstance amounted to 3 calculated as v I straight-runfigasoline and the mixture agitated;

for about 2 hours. At theend of this period any undissolved material was separated by filtration.

Analysis of the resulting of lead per 10 00.

As describedin Example 1, a sample of sulphuric. acid-treated crackeddistillate was titrated with alkali before and after being 'subjected'to' 1 hydrolysis in aqueous alcohol. From' *these titraf:

clear solution indicated m I ylate solution were mixed in 1 I Another --sam 1e sulphate) was formed.

tions it wasestimatedthat 38.5 volumes of the lead cresylate solution. were required to react with the alkyl sulphates in 350 'voluines' of the acid-treated distillate. When distillate andcresthis, proportion by volume and allowed to stand overnight, considerable white lnsoluble material was formed. This wasr'emoved byffiltration and the filtrate then' distilled, taking-over that portion boiling up to 400 'F. 'Tneproporuonaof acidic bodies formed during distillation was determined as in Example 1. This wasfound to;bej0.027 percent.

of the Same acid-treated distillate, without prior addition of cresylate solution, yielded 0.039 per cent acidic'bodies when distilled in like manner. Examplev 3.-Equal parts hour at50? C. The, reaction mass was then cooled and leached with benzol. Analysls of the resulting clear solution indicated it contained 0.0336 .gramof mercury per 10 cc.

Titration with alkali of a sample of sulphuric acid-treated cracked distillate before and after :hydrdlysis, as described in Example 1., indicated that 5.5 volumes of the mercury cresylate solution were required to reactwith the'alkyl sulphates in 350'volumes of the treateddistillate. When the liquids were mixed in this proportion by volume and allowed tostand for several hours much white precipitate (presumably "mercuric This was separated by filtration. The resulting clear filtrate was washed with per centaqueous caustic soda to eliminate any dissolved cresols. 1. On distillation'of the soda Washed liquid,,taking over the portion boiling up to 400 F., the proportion of acidicbodies formed (and calculated as sulphuricacid) was ascertained to be 0.017 percent .;Another sample of the same treated distillate,

' without'prior addition of mercuric cresylate solu 'tion, yielded 0.027 per cent of acidic bodies when distilled in like manner.

Example 4.-The proportion of alkyl deriva-' tives of sulphuric acid in a sample of acid-treated cracked distillate wasestirnated as described .in

Example '1. In this instance it was found'that' 11 volumes of a leadphenolate solution (in gasoline) were required for 450 volumes of the acidvtreated distillate. (The phenolate solution con-' tained 0.1425 gram of lead'per no.) A blend of the liquid ingredients in this proportion was i made, allowed to stand-forseveral hours at room temperature, separated'from the precipitated lead sulphate-and then distilled taking over the portionboiling up to 400 F. The totalacidity developed during distillation was determined, as indicated in Example 1, and this amounted to (1.002 per cent. l i

Another portion of this same acid-treated distillate was distilled without lead phenolate. In thiscase the'total developed acidity amounted to 0.024 percent.

The quantity of 'alkyl derivatives of sulphuric acid will depend very largely upon the concen-:

tration' of acid employed in refining and the period of time the acid and cracked ,distillateare in contact; For this reasonthe proportion of metallic phenolate required to suppressdevelopment or formation of acidic bodies during distillation of different acid-treated distillatesiwill vary con siderably. vBy the term acid-treated distillate as used herein I mean cracked or pyrolyzed petrole-' um (or its various fractions) which has been subjected to theaction of sulphuric acid. a

by weight of mixed j cresols (meta and para) and mercuric oxide were heatedfor l esters of sulphuric acid prior application of I am aware that many 'sub'stances of an alkaline nature, such as soda ash, caustic soda',vor

alkali soapslo-f fatty acids havebeen proposed. as

agents for the suppression of sulphur dioxide and other acidic bodies duringacid treated cracked: distillat'es. Such compounds, however, exhibit a' limited solubility= .in

petroleum hydrocarbons. Furthermore, it apthe distillation of pears theyare active agents mainly-at elevated;

temperatures.

For example, these alkaline sub-. stances (either as such or as concentrated aqueous I solutions) may. be incorporated with the acids treated-hydrocarbons as the-latter are being dis i tilled. Or the hydrocarbon liquid: may be-"pre-i treated with the alkaline agents (generally at elevated temperatures and underhigh pressures) before distillation.

The refining agents Iprefer, according to my invention, are compounds which are soluble in petroleum hydrocarbons and which interact with 'alykl derivatives of sulphuric acid in such a manter compounds therefore will contain an aromatic nucleus and abranched-chain alkyl radical; "Both of these factors should cause the ethers (provided they possess the requisite boiling range) to exhibit high antiknock values when employed in fuels, such as gasolines, intended for internal combustion engines of the spark-ignition type. Gasolines obtained from acid-treated cracked distillates, subjected to the action of phenolic derivatives (according to my invention) and subsequently distilled, may contain a small proportion of such alkyl phenyl ethers which should enhance their value as motor fuels. j I

On the other hand, alkyl sulphuric acids may interact with metallic phenolates to give the corresponding phenolic bodies and the metallic salts of alkylsulphuric acids. Distillation of acidtreated distillates, whih contained alkylsulphuric' acids and were treated'with metallic phenolates, may yield fractions; having a small proportion of free phenolic bodies. Since the lat- .lead sulphate and alkyl phenyl ethers. The .lat-* ter are known to be good antioxidants their presence, in small amounts, shouldrender the distilled fraction less susceptible to deterioration at tributable to oxidation. In the case of cracked likely to develop gum during storage or when in contact with the atmosphere.

By the term heavy metal as used herein It mean gasolines, for example, the liquid wouldbe less those metallic elements which are not classed either as alkalies (e. g.

sodium, potassium,

lithium) or as alkaline earths (for example, cal- I cium, strontium or bariumL generally characterized by their ability; to form sulphides which are substantiallyinsoluble in water and not readily decomposed thereby.

- What I claim is:

l. The process whch comprises treating a sul phuric acid-treated {cracked petroleum distillate Heavy metals are with ajhydroc'arbon soluble heavy metal salt of a phenolic body selected from theclass of sub stances consisting of phenol and its homologues, allowing insoluble metallic compounds to form 'andseparating said insoluble compounds, Whereby? the ability of said distillate to develop acidic compounds on distillation is suppressed. I

2. The process which comprises treating a sulphuric. acid-treated cracked petroleum distillate with a'hydrocarbon-soluble lead salt of carbolic acid, allowing insoluble lead compounds to form and separating said insoluble compounds, whereby the ability of said distillate to develop acidic compounds on distillation is suppressed.

consistingpf phenol and itshomologues ;4. .The process, according toplaim 3, in-yvhicli the phenolicbody carbolic acid. 5. The process, according to claim 3; inwhi h the hydrocarbon-soluble salt is a lead salt.