US2244164A - Treatment of light petroleum distillates - Google Patents

Description

June 3, 19M.. A. LAZAR ETAL. 2,244,164

` TREATMENT OF LIGHT PETROLEUM DISTILLATES yOriginal, Filed March 31. 1937 Patented June 3, 1941 'raEarMENr or maar PETROLEUM msrmnrEs Arthur maar, Berkeley, and Thomas F. McCormick, Oakland, Calif., assigner-s to Tide Water Associated Oil Company, San Francisco, Calif., a corporation of Delaware `Application March 31, 1937, Serial No. 134,020, which is a division of application Serial No. 67,370, March 5, 1936. Divided and this appli-v cation May 23, 1938, Seal N0. 209,597

(c1. 19e-sn 3 Claims.

This invention relates to the recovery of byproducts from the refining of petroleum which have properties making them extremely valuaable for uses hereinafter described.

The principal object of. this invention is to treat light petroleum distillates in such a manner that valuable by-products can be recovered in additional to normal petroleum products, thus making petroleum an entirely new source'for the manufacture and recovery of a number `of organic compounds.

Another object is to so treat petroleum distillates with selective solvents of various characteristics that a separation of component hydrocarbons in a distillate, (whether derived from a cracking process or not) can be effectedwith minimum losses.

Another object is to so treat and separate impurities from a petroleum distillate of definite boiling range that a motor fuel of low sulphur content and bhigh anti-knock value is obtained.

Another object is to provide an improved process for recovering sulphonic acids from acid sludges, whether such sludges are derived fromv the herein described treating steps or from other treating processes.-

Another object is to provide an improved process for isolating groups of aromatic hydrocarbons, or sulphonic acids derived therefrom.

Another object is to provide for the separation of a petroleum distillate so that substantially pure saturated hydrocarbons (parailines and naphthenes) and pure aromatic hydrocarbons can be recovered. 1

Further objects will become apparent 'as the irgention becomes more fully disclosed hereina er.

Certain mineral oil distillates, such as those produced from California crudes, contain appreciable quantities of non-hydrocarbon impurities. In reiining such distiliates, particularly those comprising the normal boiling point range of gasoline, petroleum spirits, and kerosene. it is found that the presence of these non-hydrocar-v bons interferes to a certain extent with the usual treating methods applied on said distillates.

Chemically speaking these non-hydrocarbons consist of organic acids, such as naphthenic acids, phenols, and the like, sulphur compounds of acidic nature like mercaptans and thiophenols,

lother sulphurl compounds, and nitrogen bases.

Since the organic acids and nitrogen bases are also attacked by sulphuric acid, which is the treating agent generally used for refining petroleum products, these compounds will consume a certain amount of the treating agent before the acid could have effected any actionupon the undesirable hydrocarbons to be removed.

In addition it has often been found that distillates containing such impurities cause didiculties in subsequent processing. For example,

if the distillates containing said non-hydrocarbons are treatedwith liquid sulphur-dioxide-or other solvents according to the well-known Edeleanu process, it has been found that salts of nitrogen bases and resinous deposits are formed in the treating equipment. The salt crusts represent reaction products of sulphurous and sulphuric acid with nitrogen bases mixed with resinous material, which has been formed by polymerization of the phenols. Such deposits often are quite troublesome and can be the cause of the emulsions inthe SO2 or other treating process, or, when accumulated in large quantities can interfere with heat transfer in the exchangers and evaporators of the treating unit,

`or when accumulated in lines and pumps, can

interfere with the through-put of the plant.

It' is therefore an object of this invention to submit mineral oil distillates composed of a plurality of fractions to a number of treating steps in the proper sequence and thereby to split the fractions up in such a manner that valuable organic products are obtained which heretofore could not be obtained from mineral oils in any appreciable quantity.

Broadly speaking, the invention involves the treatment of a petroleum distillate (cracked or uncracked) with 'specic reagents-in such sequence of steps that such reagents, which cannot under usual conditions exercise their function of selectivity, are enabled to be applied with' complete selectivity.

This will bebetter understood infor instance, the reactions of sulphuric acid with hydrocarbons is considered when a certain concentration of sulphuric acid is ineffective to dissolve, or react with, unsaturated andaromatic hydrocarbons, while other concentrations may be used to eiectively separate-unsaturated and aromatic hydrocarbons from saturated hydrocarbons and from each other. action of sulphuric acid and of solvents such as liquid sulphur dioxide, benzol-sulphur dioxide, phenol, furfural, nitrobenzene, dichlorethylether, a mixture of propane and cresylic acid, and like solvents, or a combination of any of these sol'- vents with each other or with liquid SO2, for hydrocarbons and impurities in hydrocarbons, is so utilized herein that a rened petroleum distillate of improved qualities is obtained while pure hydrocarbons of definite characteristics and pure by-products are made available for varied uses in the arts.

More specifically, the invention is applicable to the treatment of a petroleum distillate of gasoline boiling range (whether cracked or not) to assure a highly refined motor fuel of low sulphur content and high anti-knock value.

Referringto the diagrammatic flow sheet of the drawing, a light raw distillate obtained from California crude petroleum, such as the gasoline, kerosene, or petroleum spirits fractions thereof is the original stock to be treated.

Such raw distillate may be, merely by way of illustration and not of limitation, a selected cut In consequence, this selective v from a crude oil within the boiling range of a u following physical characteristics:

Gravity A. P. I 50.7 Initial boiling point F 155 End point F 470 Sulphur per cent-- 0.12

Nitrogen do 0.08

Aniline point F 127 As before stated, it must be understood that steps of the process are particularly applicable to any selected overhead distillate from petro- -leum which ranges in volatility from the light gasoline cuts right through the various boiling ranges of petroleum spirits, kerosene, gas oil, spindle oil, and spray oils down to heavy viscous lubricating oils and the treatment of a gasoline fraction is described as being illustrative of a fuller range of operations which will include the recovery of a very superior motor fuel as well as other included purified products.

The raw distillate, depending on its boiling range, is subjected to a series of steps for therernoval of impurities and recovery of finished products.

Preferably the raw distillate is first treated with a solution of alkali, such as caustic soda solution of a concentration of about from 15 B. to 30 B. which serves with proper agitation to combine with the organic. acids in the distillate and to break up the combination between the organic acids and nitrogen bases in the distillate while polymerizing certain unstable resinous compounds therein and the thus reacted caustic with absorbed material is removed from the distillate.

The distillate is then agitated with sufficient l to prepare the distillates for solvent refining. In

commercial operation certain stocks may require the neutralization of the last traces of sulphuric a-cid with caustic soda or other alkalies before solvent refining,

The thus withdrawn caustic solution may be acidified with fresh acid which serves to throwY the absorbed organic acids out of solution for recovery as such, while the spent dilute acid may be causticized with fresh caustic soda solution tc throw out the nitrogenous bases for recovery as such.

If separate recovery of the organic acids and nitrogenous bases is not desired, the thus spent caustic solution and spent dilute acid may be mixed to effect mutual 'neutralization which yields two layers of liquids, the upper layer comprising an oily mixture of the abstracted organic acids and nitrogenous bases very valuable as a disinfectant oil, while the lower water layer represents substantially a. solution of sodium sulphate.

In must bo understood that while the above do.

scribed removal of organic acids and nitrogenous bases is preferably done as the first step of the proc-ess so that the remaining steps of the process may be more clearly illustrated and facilitated, such removal is not essential as a first step but may be performed as a later step as will be later more fully described.

The thus purified distillate is then subjected to treatment with a' solvent such as liquid sulphur dioxide, or any of .the other described and well known selective solvents, in a well known manner to separate the distillate into two portions or layers.

The upper layer is known las the raiiinate composed of the paraliine and naphthene series of hydrocarbons and the lower layer (termed the extract) consists mainly of the olefine, dioleiine, and aromatic series of hydrocarbons together with a certain percentage of saturated hydrocarbons of the parafne and naphthene series and certain sulphur compounds.

The raiiinate comprising a puriiied motor fuel of definite boiling range but of relatively low anti-knock value may be then used as such after the usual removal, or neutralization, of contained SO2, but the invention comprehends its blending with products later derived from the extract to form a finished motor fuel of satisfactory ignition and detonation characteristics.

Depending on required uses, the extract after removal of SO2 therefrom may either be used as is or first subjected to treatments -in certain steps to derive certain products or to leave a fraction of high anti-knock value to be added to said raffinate.

The extract of gasoline boiling range is rst treated with sulphuric acid of a concentration from HzSOi up to Ia fuming acid containing 20% S03, depending on the action desired on the extract, and all treatments of the distillate or extract with the reagents described and used herein are preferably conducted for the fullest contact emciency as for .example in accordance with the method disclosedin a co-pending application of Edwards and Stark, Serial No. 532,000 filed April 22, 1931, the range of temperatures used therewith being regulated from below F. up as high as 80? F., Adepending on the solvent'or sulphonating effect required from the sulphuric acid.

If organic acids and nitrogenous baseshave already been removeci from the extract of definite boiling range, the extract will be contacted with sulphuric acid of 90% concentration, or greater, insuch quantity and at such temperature as to leave an extract composed mainly of hydrocar-v bons of a cyclic structure, .such as aromatlcs and hydroaromatics. y

The acid treated extract, as such, or fractions of the same have unique properties which make them suitable as a varnish and lacquer diluent in place of the commonly used coal tar diluents. It shows a high compatibility for nitro-cellulose and synthetic resin solutions which are used in the manufacture of lacquers and enamels. On account of its high solvency power for resins,

- gums, rubber and the like, it can also be used in place of the high priced turpentine. fFurthermore, due to its aromatic nature it has a higher afiinity for vapors of a low boiling range than ordinaryzpetroleum distillates and therefore can advantageously be used as an absorption oil in vapor recovery plants of all kinds.

In contradistinction to SO2 extracts removed from distillates such as cracked distillates or pressure distillates, an extract derived as described from straight run distillates shows entirely dierent behavior during treatment with sulphuric acid. Treating losses are relatively insignificant with straight run extracts in comparison to pressure distillate extracts, and the products obtained by `the same degree of treatment are much superior in quality to those obtained from pressure distillate extracts. y

When a pressure distillate is treated with strong sulphuric acid (95% or more) for the purpose of removing sulphur compounds the acid chemically attacks the unsaturated hydrocarbons A large perpresent in the cracked distillate. centage of the sulphuricacid is therefore used up in this reaction and not for the removal of sulphur compounds. This involves a well known conversion of valuable hydrocarbons, as can be seen from th'e following laboratory data on acid treatment of a typical California pressure distillate. 'I'his hydrocarbon conversioni involves polymerization of lighter hydrocarbons to heavier hydrocarbons and to remove these undesirable polymers it is usually necessary to follow acid treatment of the pressure distillate with neutralization and redistillation.

. When an acid treatment of a fraction from an SO2 extract obtained 'from a California oil is compared with acid treatment of a California pressuredistillate derived from the same stock, there is a marked difference in the chemical action and the properties on the finished product resulting therefrom. Moderate quantities of sulphuric acid which would be used for desulphurization of a fraction from an SO:v extract does not appreciably attack thehydrocarbons present in the extract fraction. v

The following tabulation shows that the acid removes the sulphur compounds almost conn pletely without attacking desirable hydrocarbons of high anti-knock qualities.

Corporation, of July, 1930.

Pressure S()x distillate extract A'cid rate, lha/bbl. 98% acid 30 30 Treating loss:

By acid absorption (sludge) 4. 7 3. 5 By polymerization 5.0 None Percent by volume, total 9. 7 3. 5

Properties After After After As is and redis- As is scid Awe' 'e' l treat tilling treat distimng Gravity A. P. I- 52. 7 49. 3 52. 0 33.5 v 34. 5 sulphur, percent o. a 0. c5 0.15 o. 6s 0.10 mangimi" CW Antiknoek vaiue- -15 4o -15 +14 +18 nossay' Aniline point, F 115 125 115 46 52 Distilling range:

I. B. P 114 1% 120 280 285 150 186 164 316 315 230 288 235, 345 t347 306 356 300 370 372 367 411 365 395 393 4m 500` 400 420 4% 444 530 440 434 435 The antiknock values shown above are based on the Secondary standard of the Ethyl Gasoline The plus values signifythe tenths of cc.s of lead tetraethyl required per gallon to'make the standard equal the sample. e negative values signify the tenths of cc.s required per gallon for the sample t proportions to a raffinate or to straight run I gasoline, or pressure distillate fractions, to form the heavy ends of the distilling range, the light ends being the aforesaid ramnate, gasoline, or pressure distillate fractions, `for the purpose of obtaining a combination fuel`which has high B. t. u. values combined with good anti-knock properties and a satisfactory volatility.

The importance of this anti-knock function will be more appreciated when it is considered that the higherboiling point fractions in an ordinary gasoline have higher aniline points than the lower boiling point fractions, and tha-t the anti-knock value of its higher boiling fractions is lower than that of the lower boiling fractions.

'I he reverse of this occurs with fractions derived from the treated extract inasmuch as with increasing boiling point the aniline point decreases and the anti-knock value increases since the miscibllity of hydrocarbons with aniline is directly proportional to the anti-knock value of the hydrocarbons, and thus a very important balance 4in the Vdistillation curveand thus makes n ideal .fuel for internal combustion engines.

In addition to the many functions already described the practically complete removal of active sulphur compounds is desired during the acid treatment of sulphur dioxide or other solin this manner have excellent stability and are particularly adapted for use by the paint, varnish, and lacquer industry where stability against light and weatheringis of primary importance and there is no tendency for corrosion due to the elimination of active sulphur compounds.

In order to obtain other products, if it is .not desired to use the treated extract as above set forth, or as raw material for solvents, the whole, or part, of the extract may be further 'treated with up to 100% or more of its volume with concentrated sulphuric acid (varying from 90% acid up to 20% fuming acid) under such oonditions of temperature that all the aromatica in the extract are sulphonated and the remainder of the extract will consist of more saturated hydrocarbons (mainly naphthenes and hydroaromatics) which, when neutralized, are especially valuable as special petroleum spirits, thlnners. Stoddard solvent, or similar solvents in which extremely low sulphur content, or complete freedom from both active and less active sulphur compounds is required. Due to the naphthenic nature of this remainder it still retains ignition characteristics similar to average motor fuels and therefore can be used either straight or in blends with such fuels.

If the extract has been treated in the first place with but a small amount of concentrated sulphuric acid, for the production of solvents or motor fuel not more than about 10 polmds of acid to the barrel, merely for partial sulphur reduction, the acid sludge therefrom may be discarded,` but it it has been treated .with acid up to as high as 30 pounds of acid per barrel of extract for further sulphur reduction, the acid sludge may contain a similar concentration of sulphonic acids as is contained in the acid sludge resulting from treatment oi' the extract with 100% of its volume of concentrated sulphuric acid, and the succeeding steps are ,applicable thereto'.

Depending on the sulphur content ofthe extract the sulphuric acid treatment may be carried out in one or more steps but preferably in at least -two stages for the subsequent recovery of sulphonic acids, naphthenes, and pure aromatics. The initial puriilcation with strong acid is particularly necessary if the sulphur content of the extract is high, and mayrequire up to 30 pounds of sulphuric acid per barrel for desu]- phurization purposes. The degree oi' sulphuric acid treatment in one or more stages will depend on the sulphur content of the extract and quality and purincation of solvents, motor fuel,

sulphonic acids, saturated oils. and other byproducts desired. In the acid treatment` with two or morestages the initial 'treatment removes the more easily attacked substances such as nonhydrocarbons, di-olenes, etc. and the subsequent, treatments will start to actively sulphonate aromatics.

the acid sludges from the concentrated heavy acid treatment of upto 100% by volume or more of sulphuric acid is used. v

To definitely illustrate, we can treat a high sulphur extract with 30 pounds per barrel of strong` acid in six treats of five pounds per barrel each. The rstoneor two treats will yield sludges contaminated with the reaction products of non-hydrocarbons which may be discarded in orderto avoid contamination of sludges later derived. The remaining treats yield sludges containing substantial quantities of sulphonic acids as the sulphuric acid treatment 'starts to attack the aromatic hydrocarbons to an appreciable extent. I'hese sludges maybe a suitable source of slightly contaminated sulphonic acids, al-

though more purified by-products are obtained particularly) pure,v sulphonic acids from acid sludges formed in later treatment.'

With acid sludges containing relatively high percentages of sulphonic acids, as described, novel steps are next used on said sludges for the recovery of sulphonic acids and pure aromatica and Isuch. steps are applicable to any acid sludges containing sulphonated compounds whether derived from the before described treatment or derived from any other sulphuric acid treatment of other hydrocarbons and shows great improvement over the usual and conventional methods of treating acid sludges. Y

In the usual method, the acid sludge consisting of sulphonic acids and sulphuric acid is neutralized with calcium hydroxide which converts all the acids present into calcium salts, such as calcium sulphate and calcium sulphonates, which mixture is washed with water to leach out the water soluble sulphonates and leave the water in- 1 soluble calcium sulphate, and the sulphonates are then concentrated. This procedure is very tedious from the above described treatments` may be mixed with a volume of water amounting to about one-third (1/3) ot the sulphuric acid used on the extract which, after agitation and settling, provides two layers of liquids due to the salting out effect of the tree mineral acid on the free sulphonic acids. As a result, the mineral acid content of the upper layer is greatly reduced and the lower layer retains aminimum of organicl compounds. y.

In consequence the upper layer consists mainly of sulphonic acids and the lower layer consists mainly of sulphuric acid of` a relatively low degree of concentration.

The lowerlayer may then be drawn off and distilled under such conditions of temperature and pressure that'any traces of sulphonic acids contained'therein will be split by heat to free the aromatic hydrocarbons which can be carried off as an overhead vapor and condensed 'to yield pure aromatics. The liquid remaining in the vstill consists of dilute sulphuric acid which may 'hydrocarbons are completely eliminated andonly 75 be concentrated and recovered in any well known manner for use and is especially adapted for such recovery because of its purity and freedom ifz'lrlimlienitrogen basesearlier removed from the disther recovered from the dilute sulphuric acid during concentration, the sulphur compounds and other impurities contained in the acid sludge are apparently destroyed during distillation =and concentration` because the aromatica recovered v during thesesteps are free of such impurities.

The upper sulphonic layer can be isolated for' further purlncation, or treated by. a hydrolizing steam distillation to drive off the aromatics as overhead which are'condensed and'may be mixed with the. aromatics derived from the lower layer while the remainder of the upper layer consists of dilute sulphuric acid which can be concen trated for use as described for the remainder of the lower layer.

In theevent that the upper, or sulphonic, layer is permitted to stand for some time without distillation, it has been noted that there is a tendency for the formation of crystals of pseudocumene sulphonic acid and such crystals may be readily separated from said sulphonic layer by a centrifuge prior to subjecting the remainder of the sulphonic layer to the hydrolizing steam distillation before described. A

The aromatic hydrocarbons thus derived by the aforesaid treatments of the upper and lower layers are exceptionally pure and require only the usual neutralizing and'washing treatments prior to use and such purity is due to the prior treatment of the distillate for the removal of organic acids which otherwise would contaminate the sulphonic layer and cause secondary reactions. It may readily be perceived, for instance, that if phenols were not thus removed they would be sulphonated along with the aromatica and then later reappear as contaminating substances 4 in the resultant products.

At the same time it must be noted that wnue the described removalof organic acids and nitrosense, such for instance as are found in the U. S.

Modifications and alternanons of treltment ofA the raw distillate are those stated. t

For instance, while the treatment of/'a raw gasoline distillate has been described to yield a finished motor fuel of high anti-knock value, if the raw distillate initially is of gasoline boiling range, or of any other overlapping boiling range, the SO2 or other extract derived therefrom may be distilled to yield a light fraction within the provided in addition to gasoline boiling range and bottoms heavier than such range. Such bottoms can then be recovered asa dark liquid of high fluidity and penetrating power suitable for use -for the destruction of plant life, or a so-called weed killer, as a fuel for certain types of Diesel engines, a outback oil or solvent for asphalt, pitch, coke, heavy residua, or due to its penetrating power and wetting ability, as a iiotation oil.

The light fraction may then be treated according to the described steps for the same uses as described.

It is'thus clear by the steps enumerated that the treatment of a raw distillate may be so conducted that not only is the distillate recovered in a pure state, but that every stepassures the recovery of products of value which heretofore in most cases have been useful in only aminor degree. l

It is understood that in referring to the boiling or distillation -range of any particular` distillate that the limits of such distillation range are those included in the every day, or commercial Government or A. P. I. specifications.

It will be noted that, while certain4 of the described steps have been shown as batch operagenous bases in the original raw distillate is preferably accomplished as an initial step of the process, such removal may be effected at any .time prior to, or as far as the nitrogen bases are concerned, during the initial step of subsequent treatment with strong sulphuric acid.

The SO2 extract-may therefore be treated with caustic solution for the removal of organic acids at any time prior to treatment with concentrated sulphuric acid.

'Likewise if the son extract is met treated with.V

caustic soda solution and then treated with concentrated sulphuric acid in relatively small vol'l ume. as described, so as only to eiect sulphur removal with low sulphonation of aromatica, the

extract will then be free of nitrogenous'bases because they will be removed by the concentrated acid and also be free of organic acids and thus,

`will be in a condition suitable for use, or for sulphonatlon to yield pure aromatica.

It is\apparent that by'suitable variations of the treatments with concentrated sulphuric acid with regard to time of contact, temperature of .con-

tact,- method of contact, quantity of acids, concentration of acid, the extract can be modined toyield products suitable for the u ses enumerated and that such products may yieldvarious types of aromatics.

. For instance, if the extract is treated Yhlvith acid in a plurality of steps including a first step with a small quantity of acid, the aromatic's most -readily attacked by acid can be extracted first and successive variations of treatment can be used to provide pure aromatics of desired vcharacteristics. Such treatment by selective reactivity of sulphuric acid accomplishes partial sep aration without distillation.`

treatment of light distillates.

' lng application Serial No. 134,020, iiledv March' .tions for the sake of simplicity, many of the same may bel carried on in well known continuous operations and therefore suchdescrlptive operations impose `no limitations beyond the scope of the appended claims.

Although the above inventions have been dlrected towards the processing of'distillates and the recovery of valuable by-products therefrom, it should be understood that we also include the refinement of those light and heavy crudes containing substantial quantities of non-hydrocarbons heretofore defined. Certain California Crudes such as those originating from the Ventura, Southern California, Kettleman Hillsand Belridge iields contain appreciable quantities of non-hydrocarbons and/or unsaturated `and aromatic hydrocarbons which are desirable sources of by-products. Depending on the nature of the crude and the particular' by-product recovery desired distillation may be first used to greater advantage in the later stages of processing ,and

this mode of operation is also claimed, utilizing the inventions fully described for the preferred This application isl a division of our co-pend- 6 tract to recover a desired light fraction therefrom, and treating such light fraction. `with sulphuric acid of suicient concentration and in an amount up to 100% by volume oi the fraction to remove aromatica, sulphur' com-pounds and unsaturates and leave the remaining oil oil high naphthene content after the removal oi* acid sludge.

2. The process of preparing solvents which comprises: removing non-hydrocarbons like organic acids, sulphur compounds and nitrogen bases from a distillate of petroleum oil contalm' vamount up to.1 00% by volume of the fraction to '20 naphthene content after the removal of acid sludge.

3. The process of preparing solvents which comprises: removing non-hydrocarbons like orgame' acids, sulphur compounds and nitrogen f e from a distillate of petroleum oil containing aromatica, treating' the thus puried oil with a selective solvent to remove an extract therefrom containing mainly naphthenic, unsaturated and aromatic hydrocarbons. and treating such extract with sulphuric acid of sumcient concentration and in an amount up to 100% by volume of the fraction to remove aromatics. sulphur compounds and unsaturates and leave the rel maining oil of high naphthene content after the removal of acid sludge.

'THOMAS F. MCCORMICK.

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