US2162992A - Refining hydrocarbon distillates - Google Patents

Description

Patented June .20, 1939 PATENT OFFICE REFININ HYDROCARBON DISTILLATES Waldo C. Ault and Carroll A. Hochwalt, Dayton,

Ohio, assignors to Monsanto Chemical Company, St. Inui's, Mo., a corporation of Delaware No Drawing. Application March 3, 1936, Serial No. 66,896

8 Claims. --(Cl. 196-36) This invention relates to the refining of petroleum distillates for motor fuel purposes which are rich in impurities that impart color and odor, or are productive of gum. In addition, the invention contemplates a treatment whereby the antiknock value of the fuel is increased and the susceptibility to tetra ethyl lead is improved.

The petroleum fractions which may be treated according to the present invention are generally m made by cracking relatively higher boiling petroleum products. However, they may also be produced by polymerizing lower boiling products. In either case the raw material having the desired boiling range for motor fuel purposes may 15 be malodprous, off color, rich in gum forming.

constituents, and may frequently contain sulfur in objectionable amounts. 7 Various methods are now used torefine this, so called, raw gasoline to render it suitable for 20 motor fuel purposes. In most instances several successive treatments are necessary in order that a product having the desired properties is ultimately obtained. One common procedure for removing the sulfur and gum forming constitu- 25 ents consists in washing the raw gasoline with sulfuric acid, subsequentlywith water, and thereafter with alkali to remove residual acidity. The product is then redistilled.

An alternative procedure consists in contact- 3 ing theraw gasoline with active clay, whereby the gum forming constituents are partially separated. It is generally necessary to follow the clay treatment with a doctor treatment, which is calculated to remove objectionable odors, es- 3; Decially those attributable to' the presence of sulfur impurities. Not. infrequently this is also necessary in the case of acid treated gasoline. With either method of treatment-gum inhibitors are commonly added to the gasoline, especially if the gasoline is apt to be stored for a consider- I able period of time before use.

Present day practices share many objectionable features. acid treatment is not selective. In other words,

it not only combines with the gum forming constituents, but also with the desirable olefinic components of a raw gasoline, thereby reducing the yield of gasoline and impairing the antiknock quality of the product. A reduction in M the amount of sulfuric acid employed to reduce the loss of desirable motor fuel constituents is possible only to a limited'extent inasmuch-as a substantial amount of sulfuric acid is necessary, especially where a reduction in the sulfur content of the gasoline is desired. Because it is not Thus, for example, the sulfuric possible to improve gasoline withregard to the presence of sulfur and gum forming constituents without materially reducing the yield and antiknock properties of the fuel, refiners indulge in a -compromise between bum and sulfur im- 5 purities on the one hand and cost of refining reagents and sacrifice in yield on the other. Thus, for example, a treatment with sulfuric acid may lower the antiknock value of a fuel 5 to 15 points if a substantially gum free and low. 10 sulfurproduct is desired. At thesame time ten per cent or more of the fuel may be lost as sludge.

The clay treatment avoids certain objectionable features of the sulfuric acid treatment, but has no effect whatever on sulfur. Furthermore, the clay treatment does not eliminate the. gum forming constituents entirely, but rather. eliminates only part of these to give temporary stability and necessitates the use of so-called gum inhibitors in the finished gasoline product to attain relatively permanent stability.

Whether one employs the clay or acid treatments, it is generally necessary, in order to obtain a gasoline product having the required color stability and freedom from odor, to subject it to a sweetening treatment. This treatment requires-the use of additional chemical reagents and necessitates several additional steps in the refining operation.

In the usual sweetening reaction, the mercaptans are transformed quantitatively to disulfides. This is usually accomplished with the aid of a source of oxygen. The presence of small quantities of disulfides contributes materially to poor color stability, poor susceptibility to the effect of tetra ethyl lead, poor susceptibility to gum inhibitors, and to an actual loss in octane number. In addition, the presence of free sulfur, which is normally required in excess to assure complete conversion" of the mercaptides todlsulfides, impairs color stability and promotes corrosion. -The effect of oxygen on cracked gasolines is rather well known, and the resulting peroxidation exerts a detrimental effect on inhibitor susceptibility and antiknock properties, (see 011 and Gas Journal" of February 6, 1936, page 28 et'seq.). 1

According to the present invention, the raw 5o gasoline is treated in a manner described more fully hereinafter, whereby the following advantages and improvements over the prior processes are attained:

1. Practically complete and selective removal of gum forming constituents, without loss of desirable gasoline constituents.

2- Saving in cost of gum inhibitors, by eliminating the necessity therefor.

3. Improved antiknock properties.

4. No loss in the desired olefin or aromatic constituents.

5. Substantial reduction of sulfur impurities.

6. Improved susceptibility to, and permanence of tetra ethyl lead treatment.

'7. Improved color stability.

8. Nearly total elimination of treating reagent and processing operation costs.

9. Recovery of gum and sulfur components in a non-corrosive utilizableform.

10. General applicability of refining method to widely varying raw gasolines whereby a prodnot having a high induction period is readily and conveniently obtained.

According to one preferred embodiment of the present invention, petroleum hydrocarbon va pors of the gasoline boiling range are scrubbed continuously with a mobile liquid catalytic medium, for example, phosphoric acid, the temperature, time of contact and concentration of the acid being so adjusted with respect to each other as to convert substantially all of the gum forming and color imparting constituents and a large proportion of the sulfur impurities into materials of sufliciently higher boiling point as to separate completely by a slight dephlegmation under the conditions of the treatment without interfering with the progress of the refined gasoline vapor product. The vapors so treated are thereupon condensed and will be found to be stable both as to gum and color and have high induction period. In addition, the gasoline will be found to have an increased octane rating and require no further processing with the possible exception of the removal of hydrogen sulfide, which is efiected completely either by a water or alkaline wash. By omitting the dephlegmation and especially if the scrubbing temperature is increased substantially, a considerable portion of the gum forming constituents are carried through and condensed with the gasoline vapors. However, they have been converted into the higher boiling form and can, therefore, be isolated readily by a simple distillation or rough fractional distillation.

The following comparative analyses of a gasoline before and after treatment are typical of the results obtainable by practicingour invention:

Original Treated Bromine unsaturation number 64. 3 61. 2 Octane number i 66 68 60 Color Yellow Water white Approximate yield 98% We are aware that it has been proposed heretofore to treat various hydrocarbons with mixtures of phosphoric acid and sulfuric acid. However, we'have found that under the conditions of our process in its preferred form sulfuric acid is rapidly decomposed. We are also aware that it has been proposed heretofore to pass hydrocarbon vapors in admixture with steam over a carrier sprayed with phosphoric acid (U. S. P. 1,709,315). However; such process is ineffective or only partially effective at best and must be supplemented by additional chemical treatments, such as, for example, a hypochlorite treatment. Furthermore, the various acids of phosphorus have been considered ineffective in and of themselves for the purpose of refining raw gasoline (U. S. P. 1,914,953), and to the best of our knowledge the use of these acids has met with no commercial success in this field.

In contrast with the foregoing, the following examples illustrate specific procedures for applying the principles of our invention:

Example I A commercial cracked gasoline was treated by flash distilling the raw gasoline at a rate of 200-300 c. 0. per hour in such manner that throughout the run, vapors of substantially uniform composition were obtained which were at a temperature of approximately 175-185 C. These vapors were introduced through a quarter inch tube into phosphoric acid of approximately 100% concentration and allowed to bubble upwardly through about 6 to 10 inches of the acid which was maintained at approximately 170- 180 C. by an oilbath that surrounded all except a small portion of the upper extremity of the catalyst containing vessel. Sufllcient refiux was thus afforded in relation to the temperature, acid concentration, etc. to produce a clean separation of gum forming constituents and substantial separation of sulfur containing constituents in the form of a relatively high boiling polymer, which polymer was all retained in the catalyst containing vessel and in intimate admixture with the catalyst. This intimate mixture of polymer and catalyst was found to be at least as good a scrubbing mediuni for the purpose of our in-- vention as the acid itself.

Following condensation of the scrubbed vapors, a light aqueous alkali wash was used to remove the traces of hydrogen sulfide. The following were the characteristics of the original and the treated gasoline:

The oily polymer was formed in the phosphoric acid to the extent of about 1% of the weight of the gasoline treated. This polymer upon subsequent distillation at atmospheric pressure possessed a boil-range of 240-330 C.; only a small undistilled residue remained. Duringoperation of the process the polymer was disseminated throughout the acid in the form of tiny globules by the flow of gasoline vapors through the liquid mixture. Upon stopping the flow of vapors through the catalyst the liquid polymer rose rapidly to the surface of the acid and was thereupon separated from the acid by decantation in a substantially acidfree condition. The acid layer was thus recovered practically quantitatively' and in excellent condition for repeated use.

Example II Substitute for the catalyst of Example I a phosphoric acid composition probably consisting of a mixture of ortho, pyro and possibly some meta phosphoric acid and which can be obtained by the vapors were led to a con'denser.

carbon, et al.

dissolving approximately 7 or 8% of P205 in 100% H3PO4. Otherwise, roceed as in Example I.

The product obtained under these conditions had a gum value of three milligrams per 100 .c. c. and a bromine unsaturation number of 60.7. It is to be noted that although in this particular instance the gum value was slightly lower than that obtained in Example I with the same original gasoline, the bromine unsaturation number was also lower.

As in the previously cited example, an oily polymer was produced, and separated by decantation from the acid.

Example III Substitute for the catalyst of Example I a commercial phosphoric acid syrup of commerce which is ofapproximately H3PO4 concentration. Otherwise proceed as in Example I.

The gasoline vapor passing through the acid during the first part of the run concentrated the acid as evidenced by the presence of water in the condensate. After equilibrium acid concentration conditions had been established as indicated by the absence of water in the condensate, and the fact that the condensate became clear, the condensed product was collected in a separate receiver andwas found upon analysis to have substantially the same quality as the products of Examples I 'and II. Under the equilibrium conditions the-acid was of a concentration less than 100% of HaPO4 although the concentration was considerably above a'smeasured by the water recovered in the gasoline condensate.

Example IV A Eommercial cracked gasoline was treated in an all metal'ainit by feeding'the vapors at the temperature as set forth in Example I through four one eighth inch orifices through an 8 inch depth of H3PO4 catalyst. The vapors were treated at a rate equal to anon-2,5130 c. c. of raw gasoline liquid per hour; after passing through the catalyst, the vapors were introduced into a small dephlegmator or fractionating tower partly filled with packing for the purpose of removing the last traces of entrained and vaporized polymer. The reflux ratio to be effective for this purpose need be very small; frequently 2 to.5% is suflicient. From the top of the fractionating device After a mild aqueous alkaline wash for hydrogen sulfide removal the condensed gasoline was found to have the following characteristics, which by comparison with those of the originalmaterial further demonstrate the value of our process: v

Original Treated Gum value 179 4 Sulfur content (per cent) 0. 16 0.08 Octane value 66 68 Color Yellow Water white Oxygen bomb stability (hour s). 1. 5 8. 75

We have found that nickel or'nickel containing alloys, 'such, for example as Monel metal, are

especially suited for the catalyst containing vessel. Moreover, the presence of the polymer has a distinct corrosion inhibiting effect on the metal. In lieu of nickel or its alloys, one may substitute other materials of construction, such as It is to be understood that the temperature of the bath may be controlled by proper adjustment of the temperature of the entering gasoline vapors.

Example V By increasing the gasoline vapor temperature and the catalyst-temperature of Example IV thirty degrees centigrade'or more and otherwise proceeding as in Example IV, a substantial portion of the polymer is carried over with the gasoline vapors.

The polymer so carried over was removed by increasing the reflux ratio in the fractionator. Alternatively, the treated vapors were condensed without refractionation and the condensate containing the polymer was given a simple distillation or rough fractionation to obtain a product comparable with that obtained in the preceding examples.

The catalyst is preferably a liquid underthe conditions of the treatment and is preferably substantially insoluble in the polymer that is formed and with which it is in intimate mixture while in use. Inasmuch as the catalyst is immiscible, it separates from the polymer upon standing and may be recovered as by decantation and returned to the process. In this way the catalyst may be used indefinitely as there is no perceptible loss except that attributable to usual mechanical losses incident to the handling of any material.

While ortho phosphoric acid is admirably suited for the purpose of our process, in that it not only effects substantially complete conversion of the gum forming constituents into separable form, but in addition attains the other desirable objectives of the present invention, nevertheless other catalytic compositions may be substituted therefor. Thus, .for example, a mixture of the pyroand ortho phosphoric acids may be employed, or alternatively a mixture of the meta, pyro and ortho phosphoric acids. In lieu of phosphoric acids the corresponding phosphorous, and hypo- .phosphorous acids may be substituted in wholeor in part for the phosphoric acids. In the case of the acids of lower state of oxidation there is evidence that the materials react, at least in part, to form the more stable phosphoric acid with attending formation of phosphlne.

In addition ,to the oxygen acids of phosphorus, one may use the acid salts to replace the free acid in whole orin part. Similarly one may substitute the alkyl or ar-yl acid esters, which evidently likewise undergo some chemical change in the course of their use, but as in-the other instances, the reaction products are themselves catalytlcally active.

While from the standpoint of availability, the oxygen acids of phosphorus and their derivatives are especially suitable, we may use other known non-reducible acids of phosphorus, such, for example, as the sulfur containing acids of phosphorus or the sulfur and oxygen containing acids of phosphorus, as for example, the thlo phosphoric acid HaPSOa, or dithiophosphoric acid.

.The catalyst may be made in various-ways, for example, one may use ordinary phosphoric acid syrup of commerce, which is approximately 85% HsPOl. However, if desired, one may use H3PO4 by adding suificient P205 to the phosphoric acid syrup of commerce to combine with the free water. An excess of P205 may be added to the phosphoric acid syrup over and above that required to react with all of the water to form 100% H3PQ4, in which case one obtainsa mixture of the pyro and ortho phosphoric acid, or depend ing upon the amount of P205 added, a mixture of all three of the phosphoric acids. Instead of adding P205 to the commercial phosphoric acid, one may add P203.

The composition of the starting catalytic material may be varied considerably inasmuch as it undergoes some change with use in attaining an equilibrium. This is particularly true with respect' to the water content of the catalytic composition.

While we prefer to use a fluid catalytic composition which is immiscible with the polymer, whereby it may be separated from the accumulated polymer by stratiflcation and decantation, it is to be understood that the catalyst can be present as a solid, in which case it may be suspended or dispersed in the polymer or some other fluid inert vehicle.

A further modification of the catalytic composition consists in the use of catalytically active salts either alone or in admixture with the free acids which salts exert desirable catalytic influences. of salts of catalytically active metals, such as copper, nickel, cadmium, zinc, cobalt, chromium,

iron and other heavy metals. For this purpose one may add a small amount of a salt as for example a phosphate, of the metal to the fluid acid catalyst or one may incorporate a small amount of oxide directly to the acid, in which case'the oxide probably combines with the acid to form the salt in situ. The effect of the addition of the salts is to reduce the temperature of the reaction or the required time of contact, and to some extent in changing the nature of the hydrocarbons being treated as to improve substantially the antiknock value, while at the same time elim- .inating gum forming constituents, sulfur and the tained by effecting the reaction within a comparatively narrow range of temperature which depends to some extent on the nature of the gasoline, although it is possible to gain many of the advantages of our-invention over a comparatively wide range of temperature. In general, the temperature should be sufficiently high with respect to the time and conditions of contact between the vapor and the scrubbing medium, to convert the gum forming constituents into a physically separable form and preferably without inducing substantial condensation of the gasoline vapors. 0n the other hand, the upper limit is preferably below that temperature at which objectionable amounts of the polymer are carried by the petroleum vapors. out of the treating sysperature of the treatment at which it has an appreciable partial pressure, the polymer has been carried through the treating system into the'distillate.

We have found it desirable in operating our process to reflux or dephlegmate the vapors after treatment withv the scrubbing fluid in order to obtain a good and complete separation of the gum forming polymer from the desired refined.

gasoline vapors. In general, this separation is not diflic'ult and only a very small amount of Such effect is produced by the additionvapors of the gasoline with the scrubbing fluid V is not critical. In general, any known equipment for effecting contact between a vapor and a liquid, may be used. A very convenient procedure consists in bubbling the vapors through .a pool of the catalyst, which, of course, consists of a mixture of acid and immiscible polymer. Another method of effecting the scrubbing operation consists in spraying the liquid catalytic composition through a tower in countercurrent or parallel direction with respect to the gasoline vapors being treated. If desired, such tower may be filled with a packing, over which the liquid flows downwardly and is then recirculated.

To remove the polymer, the scrubbing medium is withdrawn continuously or periodically, permitted to stratify, whereby polymer arises to the surface and the acid settles to the bottom, after which the acid is returned to the system and thepolymer is subjected to recracking or used for other purposes, preferably after washing with water to remove water soluble constituents.

We have found that in general the presence of substantial amounts of water interferes with the effective and complete paration of the gum forming constituents from the desired gasoline constituents. However, special precautions for the removal of water are unnecessary inasmuch as amounts of water such as are commonly dissolved in gasoline are not objectionable.

In line with the foregoing, we have found'that when a catalytic composition is employed which contains a substantial amount of water, the hydrocarbon vapors passing through the acid catalyst tend to dehydrate the acid until an equilibrium is attained. As the state of equilibrium is approached, the quality of the gasoline condensate improves insofar as its gum content is concerned. Thus, if one starts a process with the phosphoric acid, the acid is concentrated until it reaches a. concentration of approximately -92% or even h gher HaPO4, depending upon the temperature of the scrubbing operation. The equilibriumis established rapidly and the gasoline required to establish this equilibrium may after decantation of the water be reprocessed. As soon as the equilibrium is established the catalyst is satisfactory for continued use. This method of obtaining a catalytic composition is in general more convenient and economical than a procedure which involves the'procurement and addition of P205 to commercial phosphoric acid syrup.

The gasoline condensate obtained after scrubbing the raw gasoline with the 'catalyticscrubbing medium usually contains a small amount of dissolved hydrogen sulflde, which is probably present in the original raw gasoline. This is removed conveniently by contacting the vapors with lime, or washing the condensed gasoline with a small amount of water or an aqueous alkaline solution of soda ash or alkali. This treatment to remove hydrogen sulflde does not in any way change the motor fuel value of the condensate,

but serves the function of reducing the odor and the alkali wash a water white gasoline is obtained which has all of the properties described heretofore.

We have also found that instead of suspending the catalytical active solid material in a mobile or liquid medium which is substantially nonvolatile under the conditions of our process, the

catalyst may be used in the form of a solid either as such, or when deposited on a solid carrier.

To illustrate the principles of the application of our invention to a process in which the gasoline is in vapor stateand the catalyst is solid:

A commercial cracked gasoline was treated by distilling the raw gasoline at a rate of. 200-300 0. 0. per hour in such manner that throughout the run, vapors of substantially uniform composition were obtained. The temperature of the stream of vapors was adjusted at 225-240 C. and subsequently the vapors were passed through a tube or tower filled with granules of pumice which was saturated with phosphoric acid. The temperature of the tower was maintained at approximately the temperature of the vapors entering' the tower. Under these conditions most of the polymer was carried from the tower into a fractionating column where the temperature was adjusted to condense 3 or 4 per cent of the product. The condensate so collected consisted predominantly of the reacted gum forming constituents in the form of a mobile liquid which was high in sulphur. The vapors from the fractionating column were condensed and were found to be of excellent gasoline fuel quality.

The tower consisted of. a two inch tube approximately thirty inches long which was lagged and electrically heated to maintain the desired temperature conditions.

In lieu of the pumice granules there were substituted granular pellets of clay made by mixing clay with approximately 25 per cent by weight of 85 per cent phosphoric acid and suflicient water to produce a moldable mix. The mix was formed into pellets and dried at 105 C., afterwhich it was packed in the tower.

Other carriers may be used, such for example as a moldable mixture of sodium meta phosphate and phosphoric acid together with activated carbon or other absorbent forms of carbonaceous materials capable of holding the phosphoric acid. Coal, coke, peat and cellulosic materials may be substituted for the activated carbon to form "a solid carrier for the active component.

As a modification of the foregoing procedure, the condensate fromthe fractionating column was delivered to the top of the catalyst tower. In this case the gasoline vapors were caused to flow upwardly in counter-current direction in respect to the mobile liquid polymer which drained over the solid catalyst and was collected at the bottom of the tower. As a further modification, by reducing the temperature of. the tower, it was possible to condense the polymer in a mobile liquid form, as formed in the tower without condensing the desired gasoline vapors which were condensed and collected separately.

In this specification we referred to the undesirable constituents of the gasoline, which are separated by our process, as gum forming constituents and in the catalized form these constituents have been referred to sometimes as polymers. separated, is in fact the gum producing fraction of the raw gasoline in the form of a polymer that includes sulphur impurities of the raw gasoline, probably in the form of a reaction product of While we believe that the material' some sort or other, it is to be understood that our invention is not limited by any theory to explain the efiects. Similarly, while we refer to the process as a catalytic process (in view of the fact that there appears to be no perceptible consumption in the acid reacting phosphorus reagent), it is to be understood that we are not in a position at this time to classify the nature of. the reactions which contribute to the success of our process.

Under the preferred'conditions of operation the Engler distillation characteristics of the raw gasoline are not changed substantially. Nevertheless, in view of the relatively wide range of temperature condition which can be used without departing from the scope of our invention, as well as the fact that chemical changes additional to those incident to gum removal may take place, especially as the reaction temperature approaches cracking temperatures, we do not limit ourselves to 'a product whose Engler distilling characteristics are exactly reproduced in the final product.

In general, we prefer to operate below cracking temperatures,.that is, temperatures such as are commonly used in the art today in converting relatively high boiling hydrocarbons to those of gasoline boiling range.

One of the distinct advantages of our process reside in the fact that widely varying raw cracked gasoline distillates may be treated without necessitating extensive changes in the treating conditions, such as temperature, time of contact, etc. Nevertheless, u nder some conditions successive treatments such as might be had by subjecting the-gasoline to two catalytic operations in series or ,by recycling the stock in a batchwise manner, fall within-the purview of our P205 the ortho phosphoric acid is probably converted to pyro phosphoric acid and perhaps to meta phosphoric acid. If. desired one-can add sufficient P205 to retain a portion thereof in unreacted form; As a rule there is sufficient water in the gasoline to combine with such P205 especially after a long period of treatment, eventhough the amount of water dissolved in a decanted raw gasoline is very small. One of the advantages of the present invention resides in the fact that the reacted P205 product is itself an excellent catalyst for the purpose of our invention.

Although we have described the principles of our invention and have set forth specific embodiments of the application thereof, it is to be 'understoodthat these are illustrative only and that the invention is not restricted to the temperatures, concentrations, etc.,'sp eciflcally set forth. 'Further, it is to be understood that our process may be operated continuously or otherwise, and at subatmospheric pressure as well as super-atmospheric pressure, if so desired.

What we claim is:

1. In a process" of treating a cracked hydrocarbon fraction of gasoline motor fuel boiling fraction by reason of the difference in vapor pres- 76 sure by contacting vapors of the said cracked hydrocarbon fraction with a catalyst, the step of efiecting conversion of gum-forming constituents and separation of the reaction products which comprises bubbling the vapors of substantially anhydrous cracked hydrocarbons of gasoline motor fuel boiling range through a liquid body comprising an acid of phosphorous at a temperature sufilciently high to avoid substantial condensation of the cracked hydrocarbons and below the temperature at which any appreciable amount of the reaction product is vaporized.

2. In a process of treating cracked hydrocarbons of gasoline motor fuel boiling range containing objectionable gum-forming constituents wherein the gum-forming constituents are converted into reaction products which are of sufficiently low vapor pressure to render them separable from the said hydrocarbons by reason of the difference in vapor pressure by contacting the vapors of the said hydrocarbon with a catalyst, the step of efiecting conversion of gumforming constituents and separation of the reaction products :which comprises bubbling the vapors of substantially anhydrous hydrocarbons of gasoline motor fuel boiling range through a liquid body comprising phosphoric acid at a temperature sufiiciently high to avoid substantial condensation of the said hydrocarbons and below the temperature at which any appreciable amount of the reaction product is vaporized.

3. In a process of treating a cracked hydrocarbon fraction of gasoline motor fuel boilin range containing objectionable gum-forming constituents wherein the gum-forming constituents are converted into reaction products which are of sufliciently low vapor pressure to render them .separable from the said cracked hydrocarbon fractions by reason of the diiference in vapor pressure by contacting vapors of the said cracked hydrocarbon fraction with a catalyst, the step of efiecting conversion of gum-forming constituents and separation of the reaction products which comprises bubbling the vapors of substantiallyanhydrous cracked hydrocarbons of gasoline motor fuel boiling range through a liquid body comprising a mixture of an acid of phosphorus and reaction products at atemperature sufficiently high to avoid substantial condensation of the cracked hydrocarbons and below the temperature at which any appreciable amount of the reaction products is vaporized.

4. In a process of treating a cracked hydro: carbon fraction of gasoline motor fuel boiling ran e containing objectionable gum-forming consti ents wherein the gum-forming constituents are converted into reaction products which are of sufliciently low vapor pressure to render them separable from the said cracked hydrocarbon fraction by reason of the difference in vapor pressure by contacting vapors of the said cracked hydrocarbon fraction with a catalyst, the step of effecting conversion of gum-form'ng constituents and separation of the reaction products which comprises bubbling the vapors of a substantially anhydrous cracked hydrocarbon of gasoline motor 'fuel'boiling range through a liquid body comprising an acid of phosphorus at a temperature between 1'70 and 240 C.-

5.'In a process of treating a cracked hydrocarbon fraction of gasoline motor fuel boiling range containing objectionable gum-forming constituents wherein the gum-forming constituents are converted into reaction products which are of sufiiciently low vapor pressure to render them separable from the said cracked hydrocarbon fraction by reason of the difference in vapor pressure by contacting vapors of the said cracked hydrocarbon fraction with a catalyst, the steps of efiecting conversion of gum-forming constituents and separation of the reaction products which comprises bubbling the vapors of substantially anhydrous cracked hydrocarbons of gasoline motor fuel boiling range through a liquid body comprising the mixture of an acid of phosphorus and reaction products at a temperaturebetween and 240 C., withdrawing a portion of the liquid catalyst body, separating therefrom reaction products and. returning the purified catalyst to the said catalyst body.

6. The process of treating hydrocarbons of gasoline motor fuel boiling range to remove gum forming constituents therefrom comprising passing vapor of the said hydrocarbons substantially free of steam at a temperature between C. and C. in contact witha catalyst comprising an acid of phosphorus that is substantially non-volatile at the temperature of the treatment whereby the treated gasoline is rendered substantially free of gum forming constituents and the reacted gum forming constituents are caused to remain with the catalyst by reason of the relatively high boiling point thereof as compared with the temperature of the treatment.

7. The process of treating hydrocarbons of gasoline motor fuel boiling range to remove gum forming constituents therefrom comprising contacting vapor of the said hydrocarbons substantially free of steam at a temperature between 175 C. and 185 C. with a liquid catalyst body comprising an acid of phosphorus that is substantially non-volatile at the temperature of the treatment whereby the treated gasoline is rendered substantially free of gum forming constituents and the reacted gum forming constituents are caused to remain in the catalyst body by reason of the relatively high boiling point thereof as compared with the temperature of the treatment. 1

8. The process of treating hydrocarbons of gasoline motor fuel boiling range to remove gum forming constituents therefrom comprising contacting vapor of the said hydrocarbons substantially free of steam at a temperature between 175 C. and 185 C. with a liquid catalyst body comprising an acid of phosphorus that is substantially non-volatile at the temperature of the treatment in a reaction zone, whereby reacted gum forming constituents are deposited in the catalyst body by 'reasonof the relatively high boiling point thereof as compared with the temperature of the treatment, withdrawing a portlon of said catalyst from the reaction zone, separating therefrom reacted gum forming constituents, returning the purified catalyst to the reaction zone and separately withdrawing treated gasoline substantially free of gum forming constituents from the reaction zone.

WALDO C. AULT. CARROLL A. HOCHWALT.