US2025255A

US2025255A - Method of treating cracked oil distillates

Info

Publication number: US2025255A
Application number: US710042A
Authority: US
Inventors: Taylor Jack Francis Mahon; Harold I Lounsbury
Original assignee: Shell Development Co
Current assignee: Shell Development Co
Priority date: 1934-02-07
Filing date: 1934-02-07
Publication date: 1935-12-24
Anticipated expiration: 1952-12-24

Description

Dec. 24, 1935. J, F Ml TAYLOR E1- L 2,025,255

METHOD 0F TREATING CRACKED OIL DISTILLATS Filed Feb. 7, 1934 2 Sheets-Sheet l bl? u ku www? Q y n r w 4 w.

Patented Dec. 24, 1935 UNITED STATES METHOD or TREATING CRACKED om msmLA'rEs v Jack Francis Mahon Taylor, Clayton, Mo., and

Harold I. Lounsbury, Wilmington, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application February '1, 1934, Serial No. '110,042

19 claims.

This application is a continuation in part of our application, Serial No. 601,880, filed March "29,1932, and is particularly concerned with cersaturated hydrocarbons which interfere with mcst treatments intended to remove sulfur compounds, thereby. decreasing the effectiveness of the treatment and increasing treating loss.

It is an object of this invention to provide an efficient method f or reducing the sulfur content of la hydrocarbon oil, whereby this removal of sulfur may be accompanied by improvements in other properties of the treated oil, such, for example, as volatility, knock rating, color, etc.

It is also an object of this invention to increase the effectiveness of the sulfuric acid treatment, or

, other similar refining treatments, with regard to the removal of sulfur from the oil distillates, thereby reducing the amount of chemicals used in the process and increasing the yield of the refined distillates. f

Broadly, the process of our invention consists of separating a distillate to be treated into a number of fractions boiling at progressively higher temperature and subjecting all of some of these fractions, separately, to chemical treating processes most suitable for each individual fraction, whereby the original sulfur compounds are ,converted into other sulfur compounds of markedly different boiling range, so that, wheneach of the treated fractions is separately redistilled, the newly formed sulfur compounds readily separate fromthe major portion of hydrocarbon components of the fraction being distilled. The resulting desulfurized fractions can then be blended to make the final product of considerably lower sulfur content, than it would have been possible to obtain from the same materiall by treating it in bulk and -redistilling or by treating its fractions separately and redistilling a composite obtained by combining the treated fractions. In the last two cases, a large portion of the changed sulfur compounds would remain within the boiling range of the nal distillate, thus diminishing the effect of treating.

According to our invention, changes in the boiling temperatures of sulfur compounds may be obtained in either direction, e. g. some fractions may be treated so as to raise the boiling points of sulfur-bearing components by converting the original sulfur compounds into higher boiling compounds, -while others may be treated to convert their sulfur compounds, into lighter compounds, for example, by reducing disulfldes or other sulfur-containing substances to mercaptans, and/or to HzS, and in either case the resulting sulfur bodies' are then removed by distillation; in case of reduction to mercaptans or to HzS these are removed as first runnings, while high-boiling sulfur compounds resulting from other refining treatments can be removed as bottoms.

Among various known chemical treatments whereby the volatilities of sulfur compounds may be changed, we found the plumbite treatment, with or without addition of free sulfur, treatments with clay or fullers earth in the vapor phase, and sulfuric acid treatments, mild treatments with AlCls a'nd similar polymerizing catalysts, very effective for raising the boiling range of sulfur compounds, while well known methods for reduction with nascent hydrogen in acidic, neutral or alkaline media, or with hydrogen in the presence of a catalyst, can be used to convert certain sulfur compounds into mercaptans and/or HaS. The extent and the general efficiency of these Vtreatments can be very accurately regulated to control the treating con 30 ditions of temperature, concentration, time o contact, etc.

It is not always necessary, however, to treat all fractions of the distillate by one of these methods, as some lof them may not contain a sufciently high percentage of sulfur to require any other treatment but a soda, or water wash. In some cases certain fractions may be sweetened either by doctor or Lachman or hypochlorite treatments and may notv require redistillation. 40 The most effective and economical combination of the various treatments can be best ascertained by preliminary tests on'a small scale, and the method and conditions selected are then reproduced on a plant scale.

While, as stated above, the objectionable fractions o sulfur-bearing hydrocarbon mixtures to be treated by our method can be ascertained by simple tests of the individual fractions into which a cracked distillate is divided by efficient fractionation, we have found a new method of selecting such objectionable fractions.

We have observed that the distribution of sulfur in narrow-boiling fractions of various cracked distillates, produced under similar or different conditions of pressure and temperature, and derived from the same or different sources, can be graphically represented by a diagram 'such as shown in Figure 2 of the accompanying drawings.

BQma-n numerals of the diagram designate frac- 00 4 tions whose major portions boil within indicated ranges. The significance of the diagram resides in the fact, based on a number of observations, that sulfur-bearing compounds of substantially any hydrocarbon mixture, and regardless of their distribution in the mixture, tend, when the mixture is subjected to cracking or destructive distillation, to become concentrated within certain definite boiling ranges of the cracked product. The shaded bands of this diagram represent the boiling ranges of substantially any cracked mineral oil distillate wherein concentrations of sulfur are relatively high, 'while the intermediate unshaded bands represent fractions with relatively low sulfur contents. The double-shaded bands indicate the narrow boiling ranges Within which the concentrations of sulfur-bearing substances are usually particularly high.

It is seen from this diagram that rthle relatively highly sulfurous fractions II, IV, VI, VIII, X and XII, lie within the following boiling ranges: (5S-80 C., 98-112" C., 12S-140 C., 15G-164 C., 172-183" C. and 192-202 C. The intermediate fractions, i. e., one below 68 C., and fractions I, III, V, VII, IX, )DI and XIII, within the boiling ranges of 80-98 C., 112-126" C., 140-150 C., 164-172 C., 18S-192 C. and from 202 C. up, usually contain lower concentrations of sulfur than the intermediate fractions of the same distillate.

This manner of distribution of sulfur, it was found, is brought about quite consistently by any known cracking'. method to which asulfur-containing mineral oil may be subjected; in general, the heating of such oil at temperatures of about 400 C. or about, either in liquid or in vapor phases would normally result in rearranging sulfur-bearing substances Awithin the distillate being cracked so that the sulfur contents of the sharply separated fractions can be represented in the manner shown in the diagram.

'Ihe above and other boiling ranges disclosed herein indicate the temperatures Within which the bulk (at least 80% by vol.) of each of the fractions is distilled under approximately atmospheric pressure bythe known A. S. T. M. method.

According to one form of our invention, we separate fractions with relatively high concentrations of sulfur from those containing less sulfur, and in doing this we prefer to select these different fractions in accordance with the diagram shown in the drawings. The fractions with relatively high concentrations of sulfur are separated from the others by sharp fractionation, so as to be within the ATS. T.M. boiling ranges set forth vkhereinbefore. Or these sulfurous fractions may be so selected as to have their 50% A. S. T. M. boiling temperatures at about 74 a: 3 c., 105 q= '3 c., 133 q= 3 c., 157 :i: 3 C., 177 q: 3 C.,and 197 :F 3 C.`,i.e. substantially within the double-shaded bands of the diagram and to be substantially free of the substances boiling outside the respective ranges of sulfurous fractions. Correspondingly, the fractions with relatively low sulfur contents may then have their 50% A. S. T. M. temperatures at about 89 :l: 3 C., 119 :l: 3 C., 145 :l: 3 C., l168 :F 3 C., 187 :i: 3 C., and be substantiallyfree of substances boiling within thel ranges of sulfurous fractions, the residual fraction boiling lsubstantially from about 202 C. up to about 220 C. or

above. We found, that the efliciency of ourk method of refining crackedv distillates is favored' .by the sharpness of fractionation of the cracked distillate, so that the less is the overlap of bo1l ving ranges of the adjacent fractions, or the wider are the gaps therebetween, the more eiilcient is the concentration of sulfur-bearing compounds in the sulfurous fractions.

The separated fractions are then subjected separately to chemical treatments under conditions most suitable for each fraction. As a general rule, fractions with low sulfur contents are subjected to such chemical or physical treatments, as alkali wash, plumbite, or doctor, or Lachman treatments, extraction with a selective solvent, etc., while at least some of the fractions with high sulfur contents are treated with a chemical reagent either more or less selectively to oxidize, or to reduce, or to polymerize, sulfur compounds, thereby producing new sulfur-con- -1 taining substances boiling outside of the boiling* the first runnings, if the original sulfur compounds were converted into lighter substances, or remain in the distillation residue, if heavier sulfur-containing substances were formedby the chemical treatment of the original fractions. The desulfurized portions of the refined fractions may then be combined with other fractions, which were or were not chemically treated, to produce the refined distillate corresponding in physical properties, such as the boiling range, to the original untreated distillate. It may be found desirable in some cases lto combine into a composite not all of the desulfurized fractions, but on'y a series of consecutive or` alternate fractions produced from either the lighter or heavier or intermediate portion of the original distillate, the uncombined fractions being used separately from the composite.

Among other rening treatments to which sulfurous fractions may be subjected, we nd the polymerizing treatment with a concentrated acid, such as hydrochloric, phosphoric, and particularlyconcentrated sulfuric acid, to be preferable in many cases. By the concentrated sulfuric acid treatment is meant an acid treatment wherein a sulfuric acid having a concentration preferably not below 70% H2S04 is employed; the treatment is carried out at a temperature which usually should not be below 32 F. o'r above 160 F. and may be so selected by actual tests, if desired. as to cause the desired polymerization and/or condensation of sulfur-bearing substances, with the least effect upon polymerizable hydrocarbons. By using this method, various sulfur compounds in these sulfurous fractions are so transformed that the bulk of the sulfur can be removed from the treated fractions by distillation, the sulfurbearing compounds remaining in the distillation residue, while the desulfurized distillates can be condensed and used for-compounding desulfurized products, such as gasoline.

With reference to various characteristics of cracked gasolines produced by our method of rening, it can be noted, that by properly selecting and controlling refining treatmentsof ,individual sulfurous fractions it was found readily possible ment in their knock ratings; the refined fractions were combined in such cases in substantially the same proportions in which the corresponding unas either of the fractions I to V or their composites, or to the higher boiling sulfurous fractions VI, VIII, X and XII, preferably after the sulfurous fraction or fractions to be so treated were chemically treated and redistilled to remove reformed sulfur compounds.

'Ihe following is an illustrative example of applying the hereinbefore outlined method of refining:

A Dubbs cracked distillate having gravity of about 60.0 A. P. I., A. S. T. M. boiling range of about 30-215 C., sulfur content of about .70% by weight and octane number '70 is fractionated into twelve overhead fractions and a residue of the following characteristics:

ing beyond the boiling ranges ,of the original fractions and then separate these portions from the bulk of each treated fraction by distillation. As an example of suitable acid treatments the following can be mentioned:

Table B lFractions Suliuric acid IV VI VIII X XII Concentration, percent by weight H1SO4 93 98 98 100 ld) Lbs/bbl 3 10 l0 6 8 Treating temperature, F 80 100 100 100 100 The tabulated specific conditions of acid treating can be varied in different cases in accordance with compositions of the individual fractions, the efforts being directed to preserve hydrocarbon components while polymerizing sulfur-bearing substances. In general, the intensities of chemi- Table A Fractions Residue 1 `1I m Iv v v1 VII VIII IX x XI XII A s.'r.M 1 c 3o e9 83 98 113 121 14o 15o 165 172 124 192 y202 A. s. '1.M. 09,2" es 80 98 110 128 138 150 163 171 183 191 202 215 sulfur percent' yweignt .1s .4o .16 .c7 .27 1.30 .7a 1. 21 .77 1.15 .74 .se .7o

Each of these fractions can be rei'lned by a method particularly effective for each individual fraction, and so that either all or some of the fractions II, IV, VI, VIII, X and XII, are separately chemically treated to segregate sulfurcontaining components into fractions boiling outside of the original boiling ranges and the treated fractions are then separately distilled to separate such sulfur concentrates from desulfurized portions. We prefer, however, to segregate some of the fractions into groups and subject such composites to suitable refining treatments, while reflning other uncombined fractions separately from each other. For example:

Fractions I, III and V, and sometimes fractions II, can be combined, washed with an alkali solution and/or sweetened by doctor or hypochlorite or some other method, and/or otherwise refined, e. g. desulfurized.

Fractions VII, IX, XI, and sometimes the fraction XII, and the residue can be desulfurized, each separately, by such treatments as a polymerizing acid treatment following by distilling each treated fraction substantially to its original boiling range. Some of these fractions can often be readily desulfurized by extraction with selective solvents, such as liquid SO2, or cold fuming H2504 (at about or below 0.n C.) We found that some of these fractions can also be sweetened and their sulfur content reduced by Lachman treatment. y

Fractions IV, VI, VIII, X andA XII are usually more difcult to desulfurize, and, while occasionally some of them may sufiiciently respond to methods of treatment proposed for fractions VII, IX and XI and the residue, it is more often preferable to subject all or at least some of these fractions to a polymerizing acid treatment under such conditions as to segregate sulfur-bearing substances into portions of treated fractions boilcal treatments for eiilcient sulfur reduction are dependent not only on the concentrations of sulfur compounds but the type or nature of the sulfur compounds. Each of the acid treated fractionsis then redistilled substantially to its original boiling range to produce desulfurized distillate, leaving a residue with high content of sulfur.

After the fractions of the cracked distillate are refined, they may be combined in desired combinations and proportions to produce either high-grade motor fuels or intermediate products,

such as Vlight naphthas, intended for further' treatment. For example, the individual or combined desulfurized fractions with relatively high contents of unsaturated hydrocarbons may be used as charging materials for production of synthetic oils by polymerization with AlCla or similar catalysts.

By carefully treating cracked distillates of gasoline type by our method it is often possible to reduce the sulfur content from as high as .70% by wt. to about or less than .20% by wt. in the distillate composed of treated fractions, said composite having substantially the same boiling range as the original distillate substantially unchanged or only slightly affected knock rating, and*-l only slightly decreased unsaturated hydrocarbon content.

According to another form of our invention' we may separate cracked distillates of a normal gasoline range into smaller number of fractions than heretofore described. In practicing this method of refining we are guided by the information provided by the accompanying diagram insofar as it. indicates the distribution of sulfur were fractionally condensed to produce the following composite fractions:

It is to be noted that these fractions represent composites o f the twelve fractions previously described and shown on the diagram. Those fractions are now found to be so combined that the higher boiling portions of the` composites con tain fractions having relatively high sulfur contents, their 90% A. S. T. M. temperatures closely corresponding to the higher boiling limits ofthe fractions II, VI, VIII and XII, each of the composites being substantially free of substances boiling within the ranges of other composites. The sulfurous fraction IV is included in this example into fraction 2, while fractionsv IX and X, are distributed between fractions 3 and 4.

These composite fractions vwere treated as follows:

Table D Fractions SulIuric acid concentration, percent by Weight 93 98 98 LbsJbbl 3 10 l0 Alkali wash, followed by doctor treatment Yes. No. No. No.

While, as amore or less general rule, the redistillation of the doctor treated light fraction is not necessary, in this particular case all four treated fractions were redistilled substantially to the boiling ranges of Table C, and the distillates combined into a composite of the following characteristics:

Table E S. 10 A. S. T. M. 90 Sulphur, percent by weight Octane No. C. F. R. research Unsaturates and aromatica, percent by volumea pipe 6, into a number of sharp cuts or fractions, A. B, C, D, E and F. In this example, the

boiling ranges of fractions produced by fractional distillation or by fractional condensation of the cracked distillate are-as follows: A, up,` to (fractions I and II); B, 80"-98, (fraction III); C, 98 to 140 (fractions 1V, V and VI); D, -150 (fraction VII); E, 150-168 (fraction VIII and the lower boiling part of IX); F, 5 168 to the end, or to about 202 (the remainder of fraction IX and fractions X, XI and XII). It will be noted that at least one of the limits of each of these fractions corresponds to a boundary between a shaded and unshaded portion of 10 the diagram shown in Figure 2. These fractions may be treated as follows: Fraction A, assumed to be easily desulfurized, may be treated with sodium plumbite, with or without the addition of sulfur, in a treater 1, 15-

and, if desired, may be fractionated in a column 8 to remove higher boiling sulfur compounds formed by chemical treatment. Whenthe sweetened fraction does not require redistillation, it

may be Withdrawn for blending through a conduit 9. The top product fromthe column 8 is withdrawn at III. An alkali wash of the fraction A may precede plumbite treatment.

Fraction B is usually low in sulfur compounds and may require little or no desulfurizing treat- 2 ment. It may be subjected to an alkali wash in a treater II and discharged through a conduit I2. If no treatment is necessary, this fraction may by-pass the heater through a conduit I3.

Fractions C and F, assumed to contain large 30|A amounts of sulfur compounds, are given polymerizing treatments in acid treaters I4 and I5l respectively, under such conditions as to segregate sulfur-.bearing substances into portions of treated fractions boiling beyond the boiling 35 ranges of the original fractions. L Thus, the sulfur compounds of the acid treated fraction C will boil above 140 C. and those of the fraction F will boil above 202 C. These treated fractions are fractionated then in fractionating columns 40 I 6 and I1, where sulfur polymers are separated and withdrawn as bottoms, thru conduits I8 and I9, and the desulfurized distillates having boiling ranges substantially corresponding to those of the original fractions C and F are Withdrawn 4.3 by means 20 and 2| as top products. v

Fraction D is assumed to be low in sulphur compounds, (at least lower than theadjacent fractions) and may require no desulfurization treatment. It could, however, be subjected to a O mild treatment, similarly to fractions A or B.

Fraction E has its lower limit on a boundary between a shaded and an unshaded portion o f Figure 2. It is, therefore, advantageous to treat it to lower the boiling points of its sulfur com- 5 pounds. This may be accomplished by treating it with hydrogen in the presence of a catalyst in a treater 22. The treated fraction is then fractionated in a column 23, and the lightl sulfur products removed at 24. The desulfurized distil- G0v late is removed as the bottom product at 25.

Any or all of the treated and/or untreated fractions may now be blended by feeding them into a manifold 26 to form the final product nal cracked distillate. Unused portions may be withdrawn separately .through

conduits

21, 28. 30, 3| and 32.

By setting forth three Aspecific examples of practicing our invention we do not intend to limit thesame to these three procedures, as it is quite evident that other forms of our refining method can be used to a great advantage over conventional treatingk methods. For example, the fol- 75 lowing schemes of combining the twelve simplest ing treatment. The refined fractions may be fractions into composite fractions may be used:

either combined into desired composites or used ramer While many other methods of combining fractions may readily be evolved from the above table used in conjunction with the accompanying diagram, we have found that those indicated above are well suited in many cases. To illustrate the `use of the Table F, the method e may be explained. The table indicates, that a sulfur-containing cracked hydrocarbon mixture of gasoline type boiling up to about 220 C. or above is separated (for example, either by fractional distillation or condensation) into three consecutive cornposite fractions: 1-at least 80% of which boil up to about 112 C., 2-at least 80% of which boil from about 112 to 164 C., and 3-having its A. S. T. M. point at about 164 C. or above, each fraction being substantially free of substances boiling within the boiling ranges of other fractions. Each of the three fractions is then subjected to a refining treatment either to desulfurize all three fractions, or to desulfurize only some of them. Our preferable method of desulfurizing one or more of the separated fractions consists of two steps: 1, the chemical treatment of the fraction, such as a polymerizing acid treatment, whereby the concentration of sulfur-bearing substances outside of the original boiling range of the untreated fraction is effected, and 2, the separation of such a concentrate from the bulk of the treated fraction by fractionation. As.

I an example, the first of the three fractions produced in accordance with the method e may be sweetened by a hypochlorite treatment; the second fraction may be subjected to a treatmentcause further reduction in the sulfur content of p A this fraction; the third fraction may be treated with 98% or 100% or even more concentrated H2SO4 at a subnormal temperature, if desired, and redistilled to remove polymerized sulfur compounds; often this fraction requires no sweetenseparately, for example, as a source of synthetic oils, solvent naphthas, etc.

In practicing our invention we also found that some of the not highly sulfurous cracked distillates do not require fractional treatments outlined above, but can be refined by: rst, being fractionated into fractions with alternate low and high sulfur contents, second, combining together the sulfurousfractions into a sulfurous compositeand combining other'fractions into a composite` with low 'sulfur content, and, third, refining each composite separately from the other; the refined composites may then be blended or used separately.

It is also within the spirit of our invention to renne by our method the portions of cracked distillates which may boil only Within a part of the range indicated on the diagram. For example, a distillate consisting only of the fractions III to VIII, i. e. boiling substantially within the range 80-164 C. (about 80% of the whole distillate), may be fractionally treated in the described manner after having been divided by fractionation into three composite fractions, for example, such as III-IV, V-'VI, and VII-VIII. We\found, that the portion of a cracked distillate boiling above 80 C. is usually far more diilicultto desulfurize than the lighter portion; therefore, our invention is particularly suited for refiningA the higher boiling' portions of cracked distillates and is especially useful for desulfurizing the middle portion of such distillates, i. e. the portions consisting either of all or some of the fractions III to X, usually containing'the bulk of sulfur-bearing substances which are diflicult to remove from the distillate.

We claim as our invention:

1. In the process of refining a cracked sulfurcontaining gasoline distillate the step of dividing said distillate by fractionation into a series of fractions boiling within progressively rising temperature ranges, one of the limits of one of the boiling temperatureranges being so selected as substantially to correspond to a boiling range limit of one of the sulfurous fractions, in which sulfur-bearing substances are vrconcentrated as the result of cracking, and to include Said sulresponding boiling range limit.

2. In the process of refining a cracked sulfur-containing gasoline ydistillate the steps of dividing said distillate byfractionation into a see ries of fractions boiling within progressively rising temperature ranges, one of the limits of one of the boiling temperature ranges being so selected as substantially to correspond ,to a boil- -ing range limit of one of the sulfurous fractions,

in which sulfur-bearing substances are concentrated as the result of cracking, and to include such sulfurous fraction into the fraction having said corresponding boiling range limit, then subjecting the last referred to fraction to a desulfurizing treatment.

3. In the process of refining a cracked sulfurcontaining gasoline distillate the steps of dividing said distillate by fractionation into a series of fractions boiling within progressively rising temperature ranges, one of the limits of one of the said boiling ranges being so selected as substantially to correspond to a boiling range limit of one of thesulfurous fractions, in which sulfur-bearing substances are concentrated as the result of cracking, and to include such s ulfurous fraction into the fraction having said corjecting the treated fraction to distillation to sep-l arate said sulfur compounds from the desulfur ized portion of the treated fraction.`

4. In the process of refining a cracked sulfurcontaining gasoline distillate, the steps of dividing the distillate into a series of fractions boiling at progressively higher boiling temperature ranges having, alternately, low and high sulfur concentrations and blending together at least two non-adjacent fractions having low sulfur concentrations.

5. In the Iprocess of refining a. cracked sulfur-l containing gasoline distillate, the steps of dividing the distillate into a Aseries of fractions boiling at progressively higher boiling tempera- `ture ranges having, alternately, low and high sulfur concentrations subjecting at least one fraction of high sulfur concentration to a desulfurizing treatment, and blending together said desulfurized fraction and at least two non-adjacent fractions having low sulfur concentrations.

6. In the process of refining a cracked sulfurcontaining gasoline distillate, the steps of dividing the distillate into a series of fractions `boil ing at progressively higher boiling temperature ranges having, alternately, low and high sulfur concentrations subjecting at least one intermediate fraction of high sulfur concentration to a desulfurizing treatment and blending together said desulfurized fraction and at least two nonadjacent fractions having low sulfur concentrations, at least one of said non-adjacent fractions boiling at a higher boiling temperature range than said desulfurized fraction, and at least one of said non-adjacent fractions boiling at a lower temperature boiling range than said desulfurized fraction.

7. The process according to claim 5 in which the fractions having lowA sulfur concentrations are combined into one composite and the resultcomposite is subjected to a desulfurlzing treatment before being blended with the desulfurized fraction originally having a high sulfur content.

8. In the process of refining a cracked sulfurcontaining gasoline distillate the steps of dividing said distillate by fractionation into a series of fractions, the upper limit of the boiling range of at least one fracton being substantially at one 5 of the following temperatures: C., 112 C., C., 164 C., 183 C. and 202 C., separately treating at least the fraction having said upper boiling range limit to raise the boiling temperatures of its sulfur compounds to temperatures 10 which are above the original boiling range of the treated fraction, and separately redistilling the treated fraction, to recover a portion there- `of having a boiling range substantially corresponding to that of the original fraction. 15

9. In the process of refining a cracked, sulfurcontaining gasoline distillate the steps of divid- `ing said-distillate by fractionation into a series of fractions, the upper limit of the boiling range of at least one fraction being substantially at one 20 of the following temperatures: 80 C., 112 C., 140 C., 164 C., 183 C., and 202 C., separately treating at least the fraction having said upper boiling range limit to raise the boilingftemperatures of its sulfur compounds to temperatures, 25 which are above the original boiling range of the treated fraction, separately distilling the ,treatedfractiom to recover a portion thereof having a boiling range substantially corresponds-N ing to that of the original fraction, and blending 30 a redistilled portion with at least the adjacent higher boiling fraction which may or may not have been chemically treated.

10. In the process of refining a cracked sulfurcontaining gasoline distillate, the steps of divid- 35 ing said distillate by fractionation into a series of fractions, the lower limit of the boiling range of at least one fraction being substantially at one of the following temperatures: 68 C., 98 C., 126 C., 150 C., 172 C., and 192 C., separately 40 treating at least the fraction having said lower boiling range limit to lower the boiling temperature of its sulfur compounds to temperatures which are below the original boiling range of the treated fraction, and separately redistilling the 45 treated fraction to recover a portion thereof vhaving a boiling range corresponding to that of the original fraction.

11. In the process of refining a cracked sulfurcontaining gasoline distillate, the steps of divid- 50 ing said distillate by fractionation into a series of fractions, the lower limit of the boiling range of at least one fraction being substantially at one of the following temperatures: 68 C., 98 C., 126 C., 150 C., 172 C., and 192 C., sepa- 55 rately treating at least the fraction having said lower boiling range limit to lower the boiling temperature of its sulfur compounds to temperatures which are below the original boiling range of the treated fraction, separately redistilling 60 the treated fraction to recover a portion thereof having a boiling range corresponding to that of the original fraction, and blending a. redistilled portion with at least the adjacent lower boiling fraction which may or may not have been chem- 65 ically treated.

12. In the process of refining a cracked sulfurcontaining gasoline distillate, the steps of divide ing the distillate by fractionation into a series of fractions, the upper limit of the boiling range 70 of at least one fraction being substantially at one of the following temperatures: 80 C., 112 C., 140 C., 164 C., 183 C., and 202 C., separately treating at least said fraction having said upper boiling range limit to raise the boiling 75 Aaoaaazns rC., subjecting this fraction to a refining treattemperature of its sulfur compounds to temperatures which fall within y,the boiling range of a higher boiling fraction of said gasoline distillate,

' separately redistilling said treated fraction to flu recover a portion thereof having a boiling range substantially corresponding to that of the original fraction, and blending the redistilled portion with at least said higher boiling fraction, which may or may not have been chemically treated.

13. In the process of reiining a cracked sulfurcontaining gasoline distillate, the steps of dividing said distillate by fractionation into a series of fractions, the lower limit of the boiling range of at least one fraction being substantially at one of the following temperatures: 68 C., 98 C., 126 C., 150 C., 172 C., and 192 C., separately treating at least the fraction having said lower boiling range limit to lower the boiling temperature of its sulfur compounds to temperatures which fall within a lower boiling fraction of said gasoline distillate, separately redistilling the treated fraction to recover a portion thereof having a boiling range substantially corresponding to that of the original fraction, and blending the redistilled portion with said lower boiling fraction, which may or may not have been chemically treated.

14. In the process of refining a cracked sulfurcontaining gasoline distillate the steps of separating from the distillate a fraction boiling substantially between 98 C. and 164 C., subjecting this fraction to a refining treatment to convert at least a substantial portion of its sulfur components into sulfur compounds boiling outside of the boiling range of the untreated fraction, and then separating the treated fraction into a portion boiling substantially between 98 C. and 164 C. and another portion containing said sulfur compounds.

15. In the process of refining cracked sulfurcontaining gasoline distillate the steps of separating from the distillate a fraction having an initial boiling temperature below 150 C. within the gasoline boiling range and boiling up to 164 C., subjecting this fraction to a refining treatment to convert at least a substantial portion of its sulfur components into sulfur containing compounds boiling above the boiling range of the untreated fraction, and then separating the treated fraction into a portion boiling up to 164 C. and another portion containing said sulfur compounds.

16. In the process of rening cracked sulfurcontaining gasoline distillate the steps of separating from the distillate a fraction having an initial boiling temperature below 126 C. within the gasoline boiling range and boiling up to 140 ment to convert at least a. substantial portion of its sulfur components into sulfur containing compounds boiling above the boiling range of the untreated fraction, and then separating the treated fraction into a portion boiling up to 140 C. and another portion containing said sulfur compounds.

17. In the process of rening cracked sulfurcontaining gasoline distillate the steps of sepa- 10 rating from the distillate a fraction having an initial boiling temperature below 98 C.y within the gasoline boiling range and boiling up to 112 C., subjecting this fraction to a. rening treatment to convert at least a substantial portion of its sulfur components into sulfur containing compounds boiling above the boiling range of the untreated fraction, and then separating the treated fraction into a portion boiling up to 112 C. and another portion containing said sulfur compounds.

18. In the process of refining a cracked sulfurcontaining gasoline distillate, the steps of dividing the distillate into a series of fractions boiling at progressively higher boiling temperature ranges having, alternately, low and high sulfur concentrations, at least one of the fractions having high sulfur concentrations boiling substantially within one of the following ranges: 68-80 C., 98-112 C., 126140 C., 15G-164 C., 172-183 C., and :lo 192-202 C., and blending together at least two fraction; having low sulfur concentrations at least one of which has a boiling temperature range above .said fraction of high sulfur concentration, and at least one of which has a boiling temperature range below said fraction of high sulfur concentration.

19. In the process of refining a cracked sulfurcontaining gasoline distillate, the steps of dividing the distillate into a series of fractions boiling 4o at progressively higher boiling temperature ranges and having, alternately, low and high sulfur concentrations, separately treating at least one fraction of high sulfur concentration to raise the boiling temperatures of its sulfur components to temperatures which are above the original boiling range of the treated fraction, "separately redistilling the treated fraction to recover a portion thereof having a boiling range 'substantially corresponding to that of the original .'0 fraction, and blending together the desulfurized fraction and the adjacent low-sulfur fraction boiling at a higher temperature range than that of the treated fraction.

JACK FRANCIS MAHON TAYLOR. HAROLD I. LOUNSBURY.