US2748055A

US2748055A - Hydrocarbon conversion process

Info

Publication number: US2748055A
Application number: US264951A
Authority: US
Inventors: Grady L Payne
Original assignee: Socony Mobil Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1952-01-04
Filing date: 1952-01-04
Publication date: 1956-05-29
Anticipated expiration: 1973-05-29

Description

HYDROCARBON CONVERSION PROCESS Grady L. Payne, Mickleton, N. J., assignor to Socony Mobil Oil Company, Inc., a corporation of New York Application January 4, H52, Serial No. 264,951

16 Claims. (Cl. 196-1411) This invention relates to a process for cracking hydrocarbon oils and particularly is directed to a method for treatment of the charge oil prior to conversion to improve the cracking characteristics thereof. More specifically, the present invention is concerned with the extraction of an aromatic-containing cracking charge stock with the extract phase resulting from previous treatment of a petroleum lubricating oil with a solvent having a preferential selectivity for the relatively more aromatic type constituents as compared with the more paraffinic type constituents and subsequent subjection of the rafiinate obtained from said extraction to catalytic cracking.

It has heretofore been known that oils having a relatively high content of aromatic hydrocarbons are less suitable for cracking than non-aromatic oils since cracking of aromatic-containing oils results in a greater degradation of the oil into undesired products such as coke and gas for a given conversion to gasoline than cracking of non-aromatic oils. Thus, the ratio of gasoline to coke or gas for a given conversion is higher when cracking nonaromatic oils than when cracking aromatic oils. In view of the foregoing, it has been proposed to remove aromatic constituents from aromatic charge oil before subjecting the same to cracking. Removal of aromatic constituents may be accomplished by treatment of the cracking charge stock with a solvent having a selective solvent power for aromatics as compared with non-aromatics. Such proposed treatment, however, has been relatively expensive due to the necessity for recovering solvent and accordingly has not been practiced in commercial operation since the improved cracking characteristics of the stock so treated have ordinarily not offset the additional operational costs involved.

It has also been known, prior to the present invention, to improve the qualities of petroleum lubricating oil fractions by extraction with a solvent having a preferential selectivity for the relatively more aromatic type constituents as compared to the relatively more parafiinic type constituents. In such prior practice, the usual procedure for solvent refining of lubricating oils has been to contact the oil stock undergoing treatment with solvent in an extraction tower. Thus, the oil charge is ordinarily introduced into the lower portion of an elongated tower while solvent is introduced into the upper portion thereof. The oil and solvent move counter-currently through the tower,

'efiicient contact between the counter-currently moving phases being generally secured by suitable distributing and contacting means, such as by contact masses, distributing plates, pierced plates, and the like. Temperature and pressure conditions are maintained in the tower to secure the formation of extract and rafiinate phases. The resulting extract phase containing the major portion of the solvent, together with extracted material removed from the oil, accumulates in the bottom of the tower. The rafiinate phase, comprising solvent insoluble constituents of the oil mixed with a small proportion of the solvent, accumulates in the upper portion of the tower. The respective phases are segregated and removed from the tower, after which the solvent is removed by separately distilling these phases, driving the solvent therefrom as 2,748,055 Patented May 29, 1956 LI overhead. The solvent so removed is thereafter condensed and recycled for further treatment of additional charge oil.

In accordance with the present invention, the extract phase resulting from refining a lubricating oil fraction with a solvent having a preferential selectivity for the relatively more aromatic type constituents as compared with the relatively more parafiinic type constituents is employed directly without distillation in extraction of a petroleum oil to be used as cracking charge stock. The extract and raflinate fractions obtained from said extraction are thereafter separated and the solvent is removed therefrom. The resulting rallinate fraction is then subjected to catalytic cracking, affording a high yield of product characterized by an improved gasoline/ coke ratio. The present method affords a combined solvent extraction procedure for treatment of petroleum lubricating oil fractions and refining process for oils to be used as cracking charge stocks with the elimination of the time-consuming and expensive distillation step heretofore employed in effecting separation of the extract phase resulting from solvent refining of lubricating oils. Ithas further been unexpectedly found in practice of the process of this invention that aromatic-containing cracking charge stocks treated with the extract phase of a solvent refined lubricating oil is advantageous since an exchange is thereby efiected between paraffinic material in the extract phase fromluhricating oil refining and aromatics in the cracking charges took. Such exchange has been'found'to resents an improved yield of cracking charge oil raflinate over that obtained in the extraction of such oil wherein the solvent is used directly.

The extracts resulting from treatment of petroleum lubricating oils with any of the solvents having a preferential "selectivity for the relatively more aromatic type constituents as compared to the relatively more parafiinic type constituents may be employed in the present process. Solvents of this class are, for example, furfural, sulfur dioxide, phenol, cresol, aniline, nitrobenzene, betabetadichloroethyl ether (chlorex) and the like. Suchsolvents may have been further modified with regard to selectivity and solvent power by the addition of inert solvents as, for example, by the addition of water, alcohols, or glycols. Of these solvents, preference'is accorded furfural and mixtures thereof. The method of the invention may be practiced in any manner in which contact between the respective oil charges and solvent or solvent mixtures is maintained and the ratfinate resulting from extraction of the cracking charge oil may be subjected to catalytic cracking under the usual conditions employed in such operations.

Reference will now be made to the accompanying drawing in order to further describe the invention.

In the drawing, lubricating oil is introduced through line 10 and the solvent used for extraction is introduced through line 11. The extraction is carried out in solvent extraction step 12 by any suitable means. The resulting lubricating oil ratfinate is passed through line 13 to solvent recovery step 14. The recovered solvent passes through line 15 and is recycled through line 16 for use in further extraction. The remaining lube oil raffinate, free of solvent, passes through line 17. The lubricating oil extract'is removed through line 18 to solvent extraction step 19, wherein it is contacted with cracking charge oil introduced through line 20. The resulting cracking charge oil rafiinate is withdrawn through line 21 and conducted to a solvent recovery step 22. Solvent recovered in such step passes through line 23 and is recycled through line 16 tothe original solvent extraction step. The remaining charge oil ratiinate, stripped of solvent, is withdrawn through line 24 and passed to catalytic cracking step 25.

The resulting gaseous products may be removed through line 26 to a suitable gas recovery system not shown. The gasoline may be removed to storage or subsequent refining through line 27. Recycle stock boiling above the gasoline range may be removed through line 28 and conducted to storage or all or a portion of such recycle stock may be conducted through line 29 and recycled to solvent extraction step 19. The charge oil extract is withdrawn through line 30 and conducted to solvent recovery step 31. The recovered solvent is removed through line 32 and recycled to solvent extraction step 12. The remaining stripped extracts are withdrawn through line 33.

The combined solvent refining and catalytic cracking process of this invention may be carried out either as a continuous operation or on a batch or semi-batch basis wherein the solvent lubricating oil extract from a previous refining step may be introduced from a suitable storage source to contact with the cracking charge oil undergoing treatment.

It is contemplated that the solvent extract of lubricating oil utilized herein as a treating medium is that obtained by the usual solvent extraction of petroleum lubricating oil stocks under conventional contacting conditions, that is, the contacting of a petroleum lubricating oil fraction characterized by an A. P. I. gravity of between about and about 40 with a solvent at a temperature of between about 80 F. and about 300 F., the volume ratio of solvent to oil being maintained between about 0.5 and about 10.0.

The cracking charge stock treated in accordance with this invention may be any of the aromatic-containing stocks heretofore employed and may contain both straight run and cracked products or a mixture of the two. Typical of the charge stocks treated are distillate fuel oils and catalytic cracking cycle stocks. Generally, the cracking charge oils treated by the present process are characterized by a viscosity (S. U. V. at 122 F.) of between about 35 and about 200 seconds and boiling within the approximate range of 3501000 F. The charge stock treated by the method described herein further generally contains at least about 25 per cent by weight of aromatic type constituents.

The term petroleum lubricating oil as used herein is in accordance with the usual significance accorded that designation and includes all the distillate obtained from the crude oil after gas oil has been expelled as well as some of the residues that are left in the still when nonasphaltie crude oils are distilled. Generally, lubricating oil fractions refined in accordance with the instant process are characterized by a viscosity (S. U. V. at 210 F.) of between about 35 and about 200 seconds.

The cracking of the rafiinate obtained upon extraction of the charge oil with the lubricating oil extract phase is carried out under conventional catalytic cracking conditions. Thus, the temperatures employed are within the approximate range of 800 to 1200 F. and the pressures are only such as are suflicient to cause the oil vapors to pass through the various steps of the process. Any cracking catalyst which has been found suitable for the conversion of high boiling hydrocarbons into the gasoline distillate range may be satisfactorily used. This includes catalysts of both natural and synthetic origin such as the various clays and other natural earths which have been treated with acids or other chemical methods and the synthetic catalysts prepared from silica and various refractory oxides, for example, gel composites of si1icaalumina, silica-zirconia, silica-alumina-chromia, silicaalumina-zirconia, silica-alumina-thoria, and the like. These catalysts may be treated and prepared by any of various well known procedures.

The procedure of this invention accordingly involves use of the extract phase from a solvent lubricating oil refining operation to extract cracking charge oils and subsequent subjection of the rafiinate so obtained to catalytic cracking. The contacting of solvent lubricating oil extract and cracking charge oil is generally accomplished at a temperature between about 60 F. and about 200 F. under conditions to give the equivalent of from 0.5 to 10 theoretical counter-current extraction stages. The volume ratio of solvent lubricating oil extract to cracking charge oil is generally between about 0.1 and about 10. The solvent lubricating oil extract, for example, the extract resulting upon treating a lubricating oil with furfural ordinarily contains 70 to per cent of the total furfural employed in lubricating oil extraction. This extract may, in accordance with the procedure of this invention, be used directly for extraction of cracking charge oils or, alternatively, the lubricating oil extract may be cooled to a temperature such that extract oil separates therefrom and the remaining solvent-enriched phase may be employed to treat cracking charge oil. The solvent power of the lubricating oil extract may also be adjusted by cooling and saturating with water and decanting the oil phase, which separates before charging to the cracking charge oil treating step. The extract phase resulting from such treatment of cracking charge oils thus contains the extracted components of both lubricating oil and cracking charge oil, which are recovered together in a single solvent stripping operation. It will accordingly be seen that although the rafiinate must be stripped separately from both the lubricating oil and the cracking charge oil, one of the two major extract stripping operations in the overall process is eliminated, namely, the stripping of the extract phase from solvent refining of the lubricating oil. Since solvent recovery represents the major processing cost of a solvent refining operation, the processing procedure described herein provides an inexpensive improved refining method for the treatment of aromatic-containing cracking charge oils.

In addition, it has been found that there is a distinct and unexpected advantage in using the solvent extract phase from a lubricating oil operation for extraction of a cracking charge oil since an exchange of paraffins in the extract phase with aromatics in the cracking charge oil is effected during contact. This exchange of aromatics for heavier paraffins is definitely advantageous as it pro vides an increased yield of good cracking stock to offset the loss of aromatics which are poor in cracking characteristics. Thus, the process described herein enables improvement in the yields of gasoline which can be obtained by catalytic cracking. In addition, the amounts of carbon deposition on the cracking catalyst are decreased so that the time of processing, particularly in regeneration of the catalyst, is materially decreased. Since the conversion of cracking charge oil to gasoline is also increased, the effect is to increase plant capacity for a given size of equipment.

The following comparative examples will serve to illustrate the improvements realized in accordance with the method of this invention. The cracking charge oil employed in Examples 1 to 3 was a distillate fuel oil stock having a boiling point of 450 to 900 F. and an A. P. I. gravity of about 20.5. The solvents used in these examples were furfural and the extract phase from a previous furfural refined lubricating oil stock. Individual samples of the fuel oil were contacted with fresh furfural and with the extract phase from a furfural refined lubricating oil stock. This extract phase contained approximately 74.5% by volume of furfural and 25.5% by volume of extracted lubricating oil components of 10 A. P. I. gravity. Such extract was obtained by contacting a lubricating oil boiling in the range of 425 to 950 F. with furfural at a temperature between about 160 and about 230 F., the volume ratio of furfural to lubricating oil being about 1.75. The extract phase used in the present evaluation was saturated with furfural at F.

The raffinate phases resulting from furfural treatment of the distillate fuel oil and treatment of said fuel oil with the furfural lubricating oil extract were evaluated as cracking charge stocks in the presence of a silica-alu- 5 mina cracking catalyst employing the TCC technique operating under the following conditions:

Space velocity, v./hr./v 0.86 Catalyst-to-oil ratio, vol 1.5 Temperature, F 880 Steam, per cent wt cycle stock having a boiling point range of 450 to 850 F. and an A. P. "I. gravity of about 17 was employed. The solvent employed was the extract phase resulting from furfural refining of a lubricating oil stock. Such extract was obtained by contacting a lubricating oil boiling in a range of 6 00 to 900 F. with furt'ural at a temperature between about 150 and about 250 F., the volume ratio of furfural to lubricating oil being about 1.5. In Example 4, the catalytic recycle stock extracted with 50% by volume of the lubricating oil extract phase at It will be noted from the foregoing results that the Y extract phase from furfural refining of lubricating oil is an efiective solvent medium for the treatment of a distillate fuel oil stock. Thus, distillate fuel oil gives a gasoline/coke ratio, upon cracking, of 2.6; the fuel oil Table I Example Number 1 2 3 Extract Phase from Fur- Solvent None fural Treatment of Wgter Lubricating Oil Sat- 0 urated at 100 F.

Solvent-to-Oil Ratio, Vol 0.33 0. 50 2.00 Temperature, "F 100 100 100 Raflinate:

Yield, Percent Vol. 'ICC Heavy Fuel Oil 77. 4 73. 2 87. 8 Extract Gravity, Specific 1.1201 1. 0823 1. 0803 Extract Viscosity, KV at 100 F 150 11 183 TCC Evaluation Charge Stock Raw Stock Raffinate Raffinate Rafiinate Properties:

Gravity, A1I 20. 5 27. 3 30. 3 28. 2

Aniline Point, "F 169 191 193 180 Yields, based on TCC Charge:

C4 Free Motor Gasoline, Percent Vol 21.0 29. 1 30. 0 31. 3

Cycle Stock, Percent Vol. 60. 7 52. 6 52. 6 54. 3

Total C4S 9. 2 13. 0 13. 7 12.6

03 Free Liquid Recovery, Percent Wt 90. 9 94. 7 96. 3 98. 2

Dry Gas, Percent Wt 7. 6 8. 1 7. 8 7. 0

Coke, Percent Wt 8.1 5. 2 4. 4 3. 4

Gasoline/Coke Ratio 2. 6 5. 6 6. 8 9. 2

110 F. resulted in a ratfinate yield increase of 65.3%, an increase in A. P. I. gravity of from 168 to 27.4, and an increase in diesel index from 24 to 51. Upon cracking this raflinate, a 30.1% vvolume yield of gasoline and a 4.3% weight yield of coke was obtained comtreated with fresh furfural, :a ratio of 5.6; and a fuel oil 4(- pared with a 19% volume yield of gasoline and an 8.8% treated with the extract phase from a previous furfural gh yi of coke h untreated recycle stockrefined lubricating oil, a ratio in the range of 6.8 to 9.2. Example 5 ShOfVS that extracting the Catalytic Cracking AS will be noted there is a fu th r advantage n recycle stock with 150% by volume of the lubricating oil, ployment of the furfurai extract phase from lubricating extract i P 795% y Volumf oil operations due to an exchange of paraflinic material fi g yleld' graYlty of thls Pmduct was in the extract phase from lubricating oil refining with 3 5 z W cracked aromatic material in the fuel oil, resulting in an imb a? 2 1:: f .3? i g and proved yield of about 88% based on fuel oil. y g y p 0V1 ng Improve economlgs E l 4 t 6 s mmarized in Table II set forth over the use of the extract phase to cycle stock ratio XaIIlP e5 0 th b1 f th employed 1n Example 4. Example 6 shows that by below, dem e a 0 6 Present Process o employing 300% by volume lubricating oil extract at de'afom'atlze Y recycle stock as shqwn F., a raflinate yield of 104.8% by volume was oby the lncleastfs 111 dlesel Index. gl'avltytained. This'material had a 265 A. P. I. gravity and The concentration of the aromatics 1n the extracted hya di l i d f 49, U ki h rafii t drocarbon phases is shown by the decreases in mixed an1- F duced 35.2% by volume gasoline and 4.8% by weight line points. In these examples, a catalytic cracking recoke. The foregoing results are summarized below:

Table II Example No 4 5 6 Extraction:

Fnrfural Extract Phase Dosage, Percent Vol. of 50 300 Catalytic Recycle Stock Extraction Temp., F. 110 110 110 Catalytic Rseztgclge Rafiinate Extract Rafiiuate Extract Rafifinate Extract Yields, Percent Vol.1

Raflinate (Paratfinic) 100- 0 65. 3 79. 5 104. 8 Extract (Aromatic) Inspections:

Gravity, API Sp. Gr.@60F Aniline Pt.. F MixedAnil' ePt.,F- Diesel Index Catalytic Cracking:

Gasoline Yield, Percent Vol Coke, Percent Wt In Examples 7, 8, and 9, comparative runs were made employing the extract phases resulting from solvent refining of a petroleum lubricating oil with furfural, phenol, and chlorex, respectively. The charge stock employed in these examples was a catalytic cracking synthetic tower bottoms having a boiling point range of 450 to 870 F. and an A. P. I. gravity of about 20.5 Individual samples of the charge stock were contacted with the extract phase from a solvent refined lubricating oil stock wherein furfural, phenol, and chlorex had been employed as the treating solvents. Such extract resulted from contacting a lubricating oil boiling in the range of 450 to 800 F. with the appropriate solvent at a temperature between about 80 and about 260 F., the volume ratio of solvent to lubricating oil being about 2 to 3.5.

The conditions of extraction and the properties of the resulting raflinate and extract phases, together with the Cat-A cracking results obtained upon cracking the rafiinate in each instance, are set forth in Table III below:

Table III catalytic cracking synthetic tower bottoms having a boiling range of 450 to 870 F. and an A. P. I. gravity of about 20.7 was extracted in a three-stage counter-current operation at temperatures of 100 to 110 F. Raffinates were evaluated for cracking characteristics by means of Cat-A type (liquid feed at 850 F.) test. In Example 10, the charge stock was extracted with aqueous furfural solvent. In Example 11, the solvent employed was the extract phase resulting from contact of a lubricating oil boiling in the range of 450 to 850 F. with furfural at a temperature between about 225 and about 275 F., the volume ratio of furfural to lubricating oil being about 3.5. In Example 12, the solvent was the extract phase resulting from contacting a lubricating oil boiling in the range of 450 to 850 F. with furfural at a temperature between about 150 to about 225 F., the volume ratio of furfural to lubricating oil being about 2. In Example 13, the solvent was the extract phase resulting from contact of Charge Stock Catalytic Cracking Synthetic Tower Bottoms Selective Solv Furtnral Phenol Chlorex Extract Phase Composition, Percent Vol.:

Oil 17 13 I7 Selective Solvent 83 87 83 Extraction Conditions (3 Stage):

Extract Phase, Percent Vol 300 200 200 Temperature, F 100 130 80 Untreated igggg Rafiinate Extract Ratrlnate Extract Raifinate Extract Bottoms Treating Yield, Percent Vol Inspections:

Gravity, API Gravity, Specific-.- Aniline Point, F Mixed Aniline Pt "F SUV 122 F. Cat A Cracking Results:

Gas, Percent Wt Gasoline, 410 F. EP, Percent Vol Coke, Percent Wt Gasoline/Coke, Vol/Wt The results obtained upon cracking the raffinates show improvement in gasoline yield and decrease in coke. As will be noted, these results were substantially the same upon cracking raffinates obtained by treating the synthetic tower bottoms with furfural, phenol, or chlorex extract resulting from previous refining of a lubricating oil.

In Examples 10 to 13, a charge stock consisting of a a lubricating oil boiling in the range of 700 to 1000 F. with furfural at a temperature between about 225 and about 275 F., the volume ratio of furfural to lubricating oil being about 3. The results obtained by refining the 5 synthetic tower bottoms with the above lubricating oil extract phases and the results obtained upon cracking of the raflinate are summarized in Table IV.

Table IV Example No Extraction:

Charge Stock Catalytic Cracking Synthetic Tower Bottoms Solvent Solvent, Percent Vol. of Charge....

Rafiinate Yield, Percent Vol. Chg

Cat A Cracking of Raftinate Yields, Based on Chg. to Cracking:

Gasoline, 410 F. EP, Percent Vol 20. 7

Coke, Percent Wt 9. 6

Gasoline/Coke Ratio 2.2 Yields, Based on Chg. to Extraction:

Gasoline, 410 F. EP, Percept Vol 20. 7

1 Contains 4% vol. water.

It will be evident from the above data that extraction of the synthetic. tower bottoms charge with practical dosages of the lubricating oil extract phases as solvent results in the production of raflinates with yields of the order of 100 to 120% based on the synthetic tower bottoms charge as compared with a yield of only 77% for extraction with fresh furfural. It is further to be noted that the solvent to oil ratio employed in the case of furfural represents the lowest operable ratio for producing the highest quantity of rafiinate. The distinct improvement in rafiinate yield is possible because of the presence of paraffins in the lubricating oil extract phase, some of which are transferred to the rafiinate phase when the lubricating oil extract phase employed as solvent is contacted with the synthetic tower bottoms charge stock. It will further be seen from the results of Table IV that the raflinates resulting from treatment with lubricating oil extract yield 50 to 100% more gasoline in cracking than the untreated material and 20 to 40% more than the raifinate produced by refining with furtural alone.

The effect of variations in dosage of lubricating oil extract employed as solvent on the yields and cracking characteristics of a catalytic cracking synthetic tower bottoms charge are shown in Examples 14, 15, and 16, of Table V. The charge stock employed in these examples was a catalytic cracking synthetic tower bottoms having a boiling range of about 450 to about 850 F. and an A. P. I. gravity of about 17. The lubricating oil extract employed as solvent was that obtained from furfural refining of a lubricating oil boiling in the range of 600 to 900 F. with furfural at a temperature between about 150 and about 250 F., the volume ratio of furfural to lubricating oil being about 1.5. Extractions were performed in a three-stage counter-current operation at a temperature of 100 F. Raffinates were evaluated for cracking characteristics by means of Cat-A type (liquid feed at 850 F.) test.

range of about 350 to about 1000 F. with the extract phase resulting from the refining of a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about to about 200 seconds with a solvent selected from the class of solvents which have a preferential selectivity for the relatively more aromatic type constituents as compared to the relatively more paraffinic type constituents, separating the resulting extract and rafiinate fractions, removing solvent from said separated raflinate fraction and subjecting the resulting rafiinate fraction, freed of solvent, to catalytic cracking.

2. A hydrocarbon conversion process which comprises extracting an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and having a boiling range of about 350 to about 1000 F. into an in-. soluble ralfinate fraction and a soluble extract fraction with the extract phase from a previous solvent refined petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds treated with a solvent selected from the class of solvents which have a preferential selectivity for the relatively more aromatic type constituents as compared to the relatively more paraflinic type constituents, separating said rafiinate fraction from said extract fraction, distilling solvent from said separated raffinate fraction and subjecting the resulting rafiinate to catalytic cracking.

3. A hydrocarbon conversion process which comprises contacting an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and having a boiling range of about 350 to about 1000 F. with the extract phase resulting from previous refining of a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds with a solvent selected from the class of solvents which have a preferential selectivity for the relatively more aromatic Table V Example No 14 15 16 Extraction:

Charge Stock Catalytic Cracking Synthetic Tower Bottoms Solvent Lubricating Oil, Lubricating Oil, Lubricating Oil,

Extract Phase. Extract Phase. Extract Phase. Solvent, Percent Vol. of Charge... 150 300.

, Rafiinate Yield, Percent Vol. Chg.. 100.0 65.3 79.5 104.8. Cat A" Cracking of Raflinate Yields,

Based on Chg. to Cracking:

Gasoline, 410 F. EP, Percent Vol 19. 0 30.1. 34.3.- 35.2. Coke, Percent Wt 8.8 4.3.. 4.6.. 4.8. Gasoline/Coke Ratio 2. 2 7.0. 7.5.. 7.3. Yields, Based on Chg. to Extraction:

Gasoline, 410 F. EP, Percent V0l... 19.0 19.6... 27.3.- 36.9.

It will be observed that in cracking the raffinate produced at the lower extract phase discharge (50%), the gasoline yield was appreciably higher and the coke yield appreciably lower than for the untreated material. However, the higher gasoline yield is offset by the treating loss incurred in the extraction. On the other hand, when extract phase dosage was increased to ISO-300%, the extraction yields were increased markedly and at the same time the yield of gasoline obtainable by cracking the raifinates increased with a concurrent slight increase in coke yield. The combined eifect of these two factors was a 50-100% increase in gasoline production and an over-all reduction in coke lay-down obtained by extracting the synthetic tower bottoms and cracking the raflinate as compared to cracking the untreated material.

I claim:

1. A hydrocarbon conversion process which comprises contacting an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and having a boiling type constituents as compared to the relatively more parafiinic type constituents, separating the resulting extract fraction and raflinate fraction, removing solvent from said separated rafiinate fraction, subjecting the solvent-free raffinate fraction to catalytic cracking, recovering gaseous products, gasoline, and oil boiling higher than gasoline and recycling said higher boiling oil to contact with the aforesaid extract phase.

4. A process for converting hydrocarbons and refining petroleum lubricating oils, which comprises extracting a petroleum lubricating oil boiling within the range of about 425 to about 1000 F. and having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds with a solvent having a preferential selectivity for the relatively more aromatic type constituents as compared to the relatively more parafiinic type constituents into an insoluble rafiinate fraction and an extract fraction dissolved in said solvent, separating said extract fraction from said raflinate fraction, removing solvent from said separated raflinate fraction, returning said solvent to further contact with said lubricating oil, directly contacting said separated extract fraction with an aromatic-containing cracking charge hydrocarbon stock having a SayboltUniversal viscosity at 122 F. of about 35 to about 200 seconds, separating the resulting immiscible extract and raffinate phases which form, removing solvent from eachof said separated phases, returning the solvent so recovered to further contact with said lubricating oil, and subjecting the raflinate phase, freed of solvent, to catalytic cracking.

5. An improved process for conversion of a catalytic cracking recycle stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 20.0 seconds, a boiling range of about 350 to about 1000" F. and containing at least about 25 per cent of aromatic-type constituents, which comprises contacting the same with the extract phaseresulting from the refining of a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds, with a solvent selected from the class of solvents which have a preferential selectivity vfor the relatively more aromatic type constituents as compared to the relatively more parafiinic type constituents, separating the resulting extract and raffinate fractions, removing solvent from said separate raffinate fraction and subjecting the resulting raflinate fraction, freed of solvent, to catalytic cracking.

6. A process for simultaneously converting hydrocarbons and refining petroleum lubricating oils, which comprises extracting a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds with a solvent having a preferential selectivity for the relatively more aromatic type constituents as compared to the relatively more paraffinic type constituents into an insoluble rafiinate fraction and an extract fraction dissolved in said solvent, separating said extract fraction from said raflinate fraction, removing solvent from said separated rafiinate fraction, returning said solvent to further contact with said lubricating oil, directly contacting said separated extract fraction with an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and having a boiling range of about 350 to about 1000 F. and having a major portion thereof boiling in the boiling range of the aforesaid lubricating oil, separating the resulting immiscible extract and rafiinate phases which form, removing solvent from each of said separated phases, returning the solvent so recovered to further contact with said lubricating oil, subjecting the raffinate phase, freed of solvent, to catalytic cracking, recovering gaseous products, gasoline, and oil boiling higher than gasoline and recycling said higher boiling oil to contact with the aforesaid extract fraction.

7. A hydrocarbon conversion process which comprises extracting an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and a boiling range of about 350 to about 1000 F. into an insoluble railinate fraction and a soluble extract fraction with the extract phase from a previous furfural refined petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds, separating said raftinate fraction from said extract fraction, distilling furfural from said separated raffinate fraction and subjecting the ra'fiinate, freed of furfural, to catalytic cracking.

8. A hydrocarbon conversion process which comprises extracting an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and having a boiling range of about 350 to about 1000 F. and containing at least about 25 per cent aromatic-type constituents into an insoluble raffinate fraction and a soluble extract fraction with the extract phase from a petroleum lubricating oil having a Saybolt Universal viscosity at'210 F. of about 35 to about 200 seconds previously refined with phenol, separating said raffinate fraction from said extract fraction, distilling phenol from said separated raffinate frac- 3?. tion and subjecting the raffinate, freed of phenol, to catalytic cracking.

9. A hydrocarbon conversion process which comprises extracting an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity atl22 F. of about 35 to about 200 seconds and having a boiling range of about 350 to about 1000 F. into an insoluble raifinate fraction and a soluble extract fraction with the extract phase from a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds previously solvent refined with beta, beta-dichloroethyl ether, separating said raffinate fraction from said extract fraction, distilling beta, beta-dichloroethyl ether from said separated raffinate fraction and subje cting .the rafiinate, freed of beta, beta-dichloro ethyl ether, to catalytic cracking.

10. A hydrocarbon conversion process which comprises contacting an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and a boiling range of about 350 to about 1000 F. with the extract phase resulting from previous refining with furfural of a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds, separating the resulting extract fraction and raflinate fraction, removing furfural from said separated rafiinate fraction, subjecting the furfural-free raffinate fraction to catalytic cracking, recovering gaseous products, gasoline and oil boiling higher than gasoline and recycling said higher boiling oil to contact with the aforesaid extract phase.

11. A hydrocarbon conversion process which comprises contacting an aromatic-containing cracking charge hydrocarbon stock having a boiling range of about 350 to about 1000 F. and having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds with the extract phase resulting from previous refining with phenol of a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds, separating the resulting extract fraction and raffinate fraction, removing phenol from said separated raffinate fraction, subjecting the phenolfree rafi'lnate fraction to catalytic cracking, recovering gaseous products, gasoline and oil boiling higher than gasoline and recycling said higher boiling oil to contact with the aforesaid extract phase.

12. A hydrocarbon conversion process which comprises contacting an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and having a boiling range of about 350 to about 1000 F. with .the extract phase resulting from previous refining with beta,

'beta-dichloroethyl ether of a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds, separating the resulting extract fraction and raflinate fraction, removing beta,beta-dichloroethyl ether from said separated raffinate fraction, subjecting the beta,beta-dichloroethyl ether-free rafiinate fraction to catalytic cracking, recovering gaseous products, gasoline and oil boiling higher than gasoline and recycling said higher boiling oil to contact with the aforesaid extract phase.

13. An improved process for conversion of a catalytic cracking recycle stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and a boiling range of about 350 to about 1000 1 which cornprises contacting the same with the extract phase resulting from the refining with furfural of a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds, separating the resulting extract and rafiinate fractions, removing furfnral from said separated rafiinate fraction and subjecting the resulting raffinate fraction, freed of furfural, to catalytic cracking.

'14. A process for converting hydrocarbons and refining petroleum lubricating oils, which comprises extracting a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds with furfural into an insoluble raifinate fraction and an extract fraction dissolved in furfural, separating said extract fraction from said rafiinate fraction, removing furfural from said separated rafiinate fraction, returning the furfural so removed to further contact with said lubricating oil, directly contacting said separated extract fraction with an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and a boiling range of about 350 to about 1000 F., separating the resulting immiscible extract and rafiinate phases which form, removing furfural from each of said separated phases, returning the furfural so recovered to further contact with said lubricating oil and subjecting the raflinate phase, freed of furfural, to catalytic cracking.

15. A process for converting hydrocarbons and refining petroleum lubricating oils, which comprises extracting a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds with phenol into an insoluble raffinate fraction and an extract fraction dissolved in phenol, separating said extract fraction from said raffinate fraction, removing phenol from said separated raffinate fraction, returning the phenol so removed to further contact with said lubricating oil, directly contacting said separated extract fraction with an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and a boiling range of 350 to about 1000 F., separating the resulting immiscible extract and rafiinate phases which form, removing phenol from each of said separated phases, returning the phenol so recovered to further contact with said lubricating oil and subjecting the ratfinate phase, freed of phenol to catalytic cracking.

16. A process for converting hydrocarbons and refining petroleum lubricating oils, which comprises extracting a petroleum lubricating oil having a Saybolt Universal viscosity at 210 F. of about 35 to about 200 seconds, with beta,beta-dichloroethyl ether into an insoluble raflinate fraction and an extract fraction dissolved in beta,betadichloroethyl ether, separating said extract fraction from said raffinate fraction, removing beta,beta-dichloroethyl ether from said separated raflinate fraction, returning the beta,beta-dichloroethyl ether so removed to further contact with said lubricating oil, directly contacting said separated extract fraction with an aromatic-containing cracking charge hydrocarbon stock having a Saybolt Universal viscosity at 122 F. of about 35 to about 200 seconds and having a boiling range of about 350 to about 1000 F., separating the resulting immiscible extract and rafiinate phases which form, removing beta,beta-dichloroethyl ether from each of said separated phases, returning the beta,beta-dichloroethyl ether so recovered to further contact with said lubricating oil and subjecting the raflinate phase, freed of beta,beta-dichloroethyl ether, to catalytic cracking.

References Cited in the file of this patent UNITED STATES PATENTS 2,024,476 Rutherford Dec. 17, 1935 2,139,392 Tijmstra Dec. 6, 1938 2,201,550 Van Dijck et al May 21, 1940 2,228,510 Dearborn et a1. Jan. 14, 1941 2,270,827 Tijmstra Jan. 20, 1942 2,279,550 Benedict et al Apr. 14, 1942 2,304,289 Tongberg Dec. 8, 1942 2,342,888 Nysewander et a1 Feb. 29, 1944 2,374,102 Jahn et a1. Apr. 17, 1945 FOREIGN PATENTS 441,104 Great Britain Jan. 13, 1946

Claims

1. A HYDROCARBON CONVERSION PROCESS WHICH COMPRISES CONTACTING AN AROMATIC-CONTAINING CRACKING CHARGE HYDROCARBON STOCK HAVING A SAYBOLT UNIVERSAL VICOSITY AT 122* F. OF ABOUT 35 TO ABOUT 200 SECONDS AND HAVING A BOILING RANGE OF ABOUT 350* TO ABOUT 1000* F. WITH THE EXTRACT PHASE RESULTING FROM THE REFINING OF A PETROLEUM LUBRICATING OIL HAVING A SAYBOLT UNIVERSAL VISCOSITY AT 210* F. OF ABOUT 35 TO ABOUT 200 SECONDS WITH A SOLVENT SELECTED FROM THE CLASS OF SOLVENTS WHICH HAVE A PREFERENTIAL SELECTIVITY FOR THE RELATIVELY MORE AROMATIC TYPE CONSTITUENTS AS COMPARED TO THE RELATIVELY MORE PARAFFINIC TYPE CONSITUENTS, SEPARATING THE RESULTING EXTRACT AND RAFFINATE FRACTIONS, REMOVING SOLVENT FROM SAID SEPARATED RAFFINATE FRACTION AND SUBJECTING THE RESULTING RAFFINATE FRACTION, FREED OF SOLVENT, TO CATALYST CRACKING.