US 2324295 A
Description (OCR text may contain errors)
July 13, 1943- A. R. GQLDsBY ET Al.` J 2,324,295
MANUFACTURE OF ANTIKNOCK MOTOR FUELS Filed DeC. 28, 1939 WL! s /dw TH /R AT RNEYS Patented July 13, 1943 2,324,295 MANUFACTURE F ANT'IKNOCK MOTOR FUELS Arthur B. Goldsby and Eugene E. Sensei, Beacon, N. Y., assignors, by mesne assignments, to The Texas Company, New
of Delaware York, N. Y., a corporation Application December 2s, 1939, serial No. 311,304
This invention relates to the manufacture of antlknock motor fuels and has to do particularly with the treatment of petroleum naphthas to improve the antiknock property.
It is known that naphthas or gasolines, consisting mainly of straight chain paraffin hydrocarbons of relatively low antiknock value, may be substantially improved in antiknock value by treatment with an isomerization catalyst, whereby the straight chain paraiiln hydrocarbons are converted into branch chain orisoparaiiin hydrocarbons of high antiknock value.
It has been found that certain naphthas, particularly those of high boiling range, or wide boiling range naphthas containing higher boiling fractions, on isomerization with catalysts, such as metallic halides, may give relatively poor results due to low octane improvement and high catalyst loss or consumption. Thishas been found particularly true of those naphthas containing substantial amounts of aromatic and/or unsaturated hydrocarbons. 'I'he aromatic and unsaturated hydrocarbons generally have a high The net advantage, therefore, of the isomerizaton of such naphthas to convert normal parafns to isoparafns may be largely oifset by the loss of the unsaturated and aromatic content.
In accordance with the present invention, naphthas, normally containing constituents which cause deterioration of the catalyst, are treated under extracting conditions with a solvent selective-for the removall of the lconstituents lwhich cause deterioration of the catalyst. The reiined naphtha, after separation of the solvent and extract, can be treated with the isomerization catalyst. whereby the antiknock property of the treated naphtha may be substantially improved, with increased effectiveness and' yield per unit weight of catalyst. The aromatic and unsaturated hydrocarbons which are re moved in the extract can be recovered for use. in blending with the isomerized product or other motor fuel base stock.
Naphthas which may be treated are of wide. variety. It is intended to treat any naphthas or gasolines, or fractions thereof, which contain a substantial proportion of low octane paraifn-hydrocarbons, as well as constituents which cause objectionable deterioration oi the catalyst.
Naphthas specicallyintended are straight run naphthas, containing aromatics and/or unsaturated compounds; cracked naphthas; mixtures of straight run and cracked naphthas; and naphthas resulting from catalytic cyclization of olens.
'I'he naphthas or-gasolines to be treated with the isomerization catalyst may be separated into two or more fractions and one or more of the fractions treated and the products blended. Thus a naphtha may be separated intoA low boiling and high boiling fractions and each fraction treated separately, or only one fraction, such as the high boiling fraction, treated. The fractions may then be recombined.4
For example, a straight run naphtha mayy desirably be separated into two fractions. One may be a low boiling fraction having an end point below the boiling point of the lowest boiling aromatic constituents in the stock in question, such as below about 200 F. The other may be a higher boiling fraction containing substantially all the aromatic content of that stock. The low boiling fraction is isomerized or may be left untreated, depending upon the octane thereof and the octane of the nal product desired. The higher boiling fraction is solvent reiined "and the 'resulting ramnate thereafter amountv of aromatics, but even a small amount is harmful to the isomerization reaction. A
cracked naphtha fraction, however, of such boling range contains unsaturated or oleflnic hy drocarbons which are advantageously removed.
Furthermore, a fraction of safety fuel boiling range, for example, a product with a flash above F., and a boiling range of about 300 to 500 F. may be treated, if desired. 'I'he preliminary, removal of aromatics and unsaturates enablesl the treated product to be successfully isomerized.
to improve the antiknock characteristics..
In case the proportion of aromatics or unsaturates in the oil is low, as in the case of some straight run paramnic naphthas, it may be de.- sirable to treat the naphtha with acid or alumlnum chloride to remove the small amount of washing with water.
aromaticsor unsaturates and then isomerize the treated product, rather than to isomerize the naphtha directly, or to solvent refine and then isomerize.4
'I'he preliminary solvent rening or extraction step may be carried out by conventional processes and with any solvent suitable for this purpose. The solvent extraction of light oils is quite well known in the art, and itis intended that any of these methods may be used. Speciilc solvents which may be mentioned are sulfur dioxide or mixtures ofsulfur dioxide with methyl alcohol, benzyl alcohol or diacetone alcohol. The
sulfur dioxide extraction is ordinarily carried out in the liquid phase at temperatures of about to 60 F. In carrying out the extraction process, the solvent is contacted with the oil under temperature and pressure conditions to cause an extraction of certain constituents such as unsaturates and oleiins, thereby forming an extract and raillnate layer, and then separating the two layers. Any solvent retained in the two layers may be removed, for example, by distillation or 'I'he ramnate layer will contain straight chain or paramn hydrocarbons of low antiknock value suitable for treatment by isomerization. Ihe extract layer after separation of the solvent will usually contain high s antiknock hydrocarbons which maybe used for motor fuel, for example, by reblending with the isomerized ramnate.
'I'he preliminary treatment with reagents, such as aluminum halides or sulfuric acid, produces' chieiLv polymerization products of the lunsaturates, or complexes or sludge with the unsaturates or aromatica, which may be separated from the treated oil as sludges. The treatment may. be conducted at low temperatures within the range specified for solvent refining or at somewhat higher temperatures. Such treatment may be economical with naphtha containing relatively small amounts of unsaturafes or aromatics or both. The treating agent is usually contacted with the oil in the conventional manner of acid treating.
I'he isomerization of straight chain paramn tion, a straight run gasoline of 100 to 390 I".
operations. In continuous or. cyclic operations,
for example wherein the oil is contacted with the catalyst in la packed tower,.the proportion of catalyst to oil undergoing treatment at any given interval of time may be considerably larger than in the case of batch operations, but the ultimate yield of total hydrocarbon treated per unit of catalyst may be considerably larger in the continuous type ofl operation.
As an example of the operation of the invening an antiknock value of about 40, are obtained. v
The ramnate is treated with about 15% aluminum chloride and 0.8% hydrogen chloride. The yieldvof treated naphtha is about 95% and the antiknock value thereof is about 65. When the extracted hydrocarbons are readded to the treated naphtha, a blend having an octane number of about '71 may be obtained. The same naphtha, without the preliminary extraction step, could not be successfully treated with the Catalysis, which have been propod for that purpo, include anhydrous metallic halides, particularly thechlorides. bromides, etc., of aluminum, zirconium. iron, zinc, tin, barium, columbium, tantalum and boron, together with small amounts of hydrogen halides, such as hydrogen chloride, as promoters. We prefer to use aluminum chloride and hydrogen chloride. 'Ihe reaction may be carried out in the liquid or vapor phase' by contacting the oil with the catalyst, alone or supported on a suitable carrier, such as clay, pumice, brick, coke, activated `alumina or carbon. It is preferable to carry out the reaction under temperature and pressure conditions such as to maintain the liquid phase. The deterioration of the catalyst may be retarded by carrying out the process in the presence of substantial amounts of low boiling isoparafiins, such as isobutane or isopentane. The temperatures are preferably in the range of about 180 1". to 270 F. although temperatures up to 360 l". or
` higher may be used.
conducted from `a source not shown through a.
pipe I is subjected to fractionation ina fractionation unit-2. to produce a fraction boiling in the range of around 1D0-200 P'. This fraction is and conducted to a receiver I.
From the receiver I the low boiling material may be passed to an isomerisation unit l wherein it is subjected to isomeriaation. The isomerized hydrocarbons are drawn of! through a pipe 5 and, all or in part, conducted to a tank 0.
The higher boiling fraction formed in the fractionation unit 2 is drawn' of! through a pipe 'i to an extraction unit 8. In this extraction unit the naphtha hydrocarbons are treated so'as to extract from them unsaturated and aromatic hydrocarbons.l 'I'his extraction may be effected by treatment with acid or aluminum chloride or by treatment with a selective solvent such as sulfur dioxide.
The vunsaturatedv and aromatichydrocarbons so extracted from the naphtha are separated fromtheextractingmediumandpassedtoa tank 9 from which they may be passed, all or in part, to the previously mentioned tank l.
The naphtha hydrocarbons from which the unsaturated and aromatic constituents have been removed are to a tank Il and from there they aresubiected to contact with an isomeriza- Insuchcaseths between about 0.1 and 5% or more. nfmbly den of ting a low boiling fraction-for about 1%. Thehtterilguresarebasedonbatth 75 @Pirate treatment is omitted.
The fractionation is such as The process of the present invention, wherein the oil is treated to remove aromatics and unsaturates, prior to isomerizatlon, produces a yield of about 80 to 95% of product showing an octane improvement of about to 40 points. Similar isomerization treatments, without the preliminary solvent extraction treatment, produce yields o'i about 50 to 80% with very little improvement obtained. In fact, some times a loss in octane may occur, due to removal oi unsaturates and aromatics. Moreover, the catalyst deterioration is usually substantially less in treating' gasolines which have,been subjected to the preliminary solvent extraction step.
Obviously many modications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirity and scope thereof. and therefore only such limitations should be imposed as are indicated in the appended claims.
1. A process involving catalytic isomerization, for improving the antiknocl-r properties of naphtha of relatively low antiknock value and normally containing constituents of the class of unsaturates and aromatics which cause deterioration of the catalyst, which comprises separating the naphtha into a low boiling fraction having an end point below the boiling range of at least the major portion of the aromatics in the stock and a high boiling fraction, solvent refining the high boiling fraction to remove coning treatment with an isomerizatlon catalyst.
' which comprises separating the naphtha yinto a low boiling fraction having an end point-,below the booling range of at least the major portion of the aromatics in the stock and a high boiling fraction, separating from the high boiling fraction a fraction' rich in aromatic hydrocarbons and comprising constituents highly reactive toward the catalyst and capable of causing substantial catalyst deterioration, subjecting the high boiling naphtha hydrocarbons from which said aromatic-rich fraction has been removed to contact with an isomerization catalyst under conditions such that isomerization of non-aromatic constituents constitutes the principal reaction and said reaction is eiected with substantial decrease in catalyst deterioration, and blending resulting isomerized hydrocarbons with at least a portion of the low'boiling fraction.
6. A process for improving the antiknock properties of naphtha of relatively low antiknock value and containing unsaturated constituents, aromatic hydrocarbons and non-aromatic hydrocarbons including paraflins, involving treatment .with an isomerizatlon catalyst, which comprises fractionating the naphtha into a low boiling stituents which cause deterioration of an aluminum chloride isomerization catalyst, subjecting the treated high boiling .fraction under isomerizing conditions with said isomerization catalyst and blending the isomerized high boiling fraction with the low boiling fraction.
2. A process according to claim 1 in which the original naphtha is a straight run product and the low boiling fraction is isomerized prior to blending with the high boiling fraction.
3. A process according to claim 1 in which the original naphtha is a cracked product and the low boiling fraction is treated to remove unsaturated products therefrom and then isomerized prior to blending with the high boiling fraction.
4. A process. involving catalytic isomerization. i'or improving the antiknock properties of naphtha of relatively low antilmock value and normally containing constituents of the class of unsaturates and aromatics which are capable of causing deterioration of the catalyst, which comprises separating the naphtha into a low boilfraction having an end point below the boiling range of at least the major portion of the aromatics in the stock and a high boiling fraction, separating from said high boiling fraction a fraction rich in aromatichydrocarbons and comprising constituents highly reactive toward the catalyst and capable of causing substantial catalyst deterioration, subjecting the llow boiling tion is eil'ected with substantial decrease in cataing fraction having an end point below the -boil- A halide isomerization catalyst under conditions such that there is substantial isomerization oi naphtha hydrocarbons, and blending at least in part isomerized high boiling fraction with the low boiling fraction.
5. A process for improving the antiknock properties of naphtha of relatively low antiknock .value and containing unsaturated constituents, aromatic hydrocarbons and non-aromatic hydrocarbons including :pai-amas. involvunsaturates and lyst deterioration. and blending resulting isomerized hydrocarbons with aromatic hydrocarbons separated from said high boiling fraction.
7. A process, involving catalytic isomerization, for improving the antiknock properties of naphtha of relatively low antiknock value and normally containing constituents of the class of aromatics which cause deterioration of the catalyst, which comprises separating the naphtha into a low boiling fraction having an end point below the boiling range of at least the major portion of the aromatics in the stock and a high boiling fraction, chemically treating the high boiling fraction to remove con- Y stituents which cause deterioration of an aluminum chloride isomerization catalyst, subjecting the treated high boiling fraction under isomerizing conditions with said isomerlzation catalyst and blending resulting isomerized hydrocarbons with at least a portion of the low boiling fraction.
8. 'I'he process according to claim -4 in which the original naphtha is obtained by catalytic conversion of hydrocarbons and the low boiling fraction is treated to. remove unsaturated products therefrom and then isomerized prior to blending with the high boiling fraction;
9. 'Ihe process according to claim 4 in which the original naphtha is obtained by cracking hydrocarbons and the low kboiling fraction is treated to remove unsaturated products therefrom and then isomerized prior to blending with the high boiling fraction.
10. The process accordingto claim 5 in which isomerized hydrocarbons, the lowV boiling fraction and aromatic hydrocarbons separated from the causing deterioration of the catalyst, which 10 comprises separating the naphtha into a low boiling fraction having an end point below the boiling range of at least the major portion of the aromatics in the stock and a high boiling fraction, separating from the high boiling fraction constituents which are capable of causing deterioration of an active metallic halide isomerization catalyst, subjecting the low boiling fraction and said high boiling fraction from which said constituents have been separated to contact with an active metallic halide isomerization catalyst under conditions such that there is substantial isomerization of naphtha hydrocarbons and forming a blend comprising isomerized hydrocarbons from both said fractions.
ARTHUR R GoLDsBY. EUGENE E. sENsEn