US2587643A - Deasphalting mixtures of hydrocarbons - Google Patents

Description

Patented Mar. 4, 1952.

DE'A'SPH'AETIV'NG MIXTURES F HYnRooARBoNs Harold C Myers}. Woodbury; N. J., assign'or to- Socony-Vacuum Oil Company; Incorporated, a:

oorporationof New York No -Drawing. Application A'ugust 27,1947,

- Serial No. 770952 10I Claims. (G1. 196-14.46)

The present. invention relates-. tothe; treatmerit. of. mixtures of hydrocarbons. with liquidnormally. gaseous. hydrocarbons and'-, morel par.- ticularly, to the treatmentof mixturesof hydro.- oarbonscontaining asphalt with liquid normal 13' gaseous hydrocarbons. and? organic. carbonates to separate an asphaltic component; I

In the' years subsequent to 1934- a, number of patients have issuedrelating, generally, to the deasph'ailtingr of mixturesi of hydrocarbons and; specifically, to" the deasphalting of" mineral oil. For eit a mplefi. U1 Si Patent'No. 948,296 contains" a: desj. ipti'on of amethod of treating crude oils. it e.- d'sphalt contaihi-ng oil's-whichhave not been subj ed t'o excessive temperatures; withsolvent's' have the function of dissolving the oil.- 7 div-not dissolve-the bitumens. Suchv sn'lvehtssare stated. inthis patent t'ov be: light petrol m"; hydrocarbons, such: as naphtha; casinghead gasoline light: petroleum: fractions composed f: propane; butane". and; isobutane; certain alcohols... ether and mixtures thereof, acetone,- etc; ater in1.U-.. S; Patent No.- $002,004 thehydrocarbons:- of. the foregoing. list of asphaltprecipitants. were: termed. normally gaseous: liquefiedhydrocarbons. 'I hus i thereis abroad. desi 'tion. 011 deasphalting. agents which inciud within itsscope: the normally gaseous. Belief-i d hydrocarbonsast a specific typeof de asph ing agent.

" r t rm asphalt, as used in generically g the material insoluble: inthe con deasphalting agents, has likewise; been veral definitions which in essence-have meaning. Thus, in Ul S. Patent; No. asphalt and bitumens. wouldappear to ymous terms; the other hand; Asphalts and Allied Substances:" 165th vol. I, page 61, defines asphalt as,.

in Chemical Refining of Petroleum?" Kali'chev pplied to a species: of bitumen," while" sky-Stagner, asphalt is defined in theGlossary of Terms as Solid or semi-solidbitumen found in nature (natural asphalt) or manufactured by the oxidation, distillation on other treatment. of mineral oils (artificial asphalt)." While these definitions diilerin some respects those skilled.

in the artlofpet'roleumx ren'nmgjwhen discussing the deasphaltingi oi; crude's or; lubricating. fractions: or: other mixtures; of? hydrocarbons: by

treatment? with. deasphai'tingf agent's cbl'i'sifif' the?suiistanceinsoliibieinthe deasphaftlnsfasents lie asphalt The terms" asphalt'f and deasnhaltinn agents used hereinafter: in: the nirwngseflcrthiihthelestsentence The: present; invention does: not include new or. novel manipulations of: the mixture of i hydrocarbons to be: deasphalted butv provides for the: use of a novel solvent mixture: in operations: disclosed. by the: prior art. Inother words; the novel solvent mixture is used. as a solvent inthe? prior art processes of deasphalting.

The novelsolventmixture. comprises amixture of one or more of. the well known or con ventional'. deasphalting. agents and a modifier; The particular mechanism by which the. modi' fien produces the novel results. not entirely understood. v That is tosay,. it is not clear whether the modifier reduces. the solubility of; the: asphalt in the: deasphaltingagent thereby reducing the Conradson number of the: rafiinatev orv decreases the solubility of the rafiinate. in the liquid asphalt thereby increasing the yield 01' whether the unexpected overall improvement is the: result of. some other phenomenon. or' phenomena. However, it has been establishing. as. shown hereinafter that improved results compared to those. of the: prior artcan be achieved. in either of two waysby the use: of a deas'phalting mixture comprising a, modifier in conjunction with a conventional deasphalting agent. That is to say, a deasphalted oil of. higher quality than that produced when treating the same charge stock with a conventional. deasphalting agent can be obtained by using one of the novel modifiers in conjunction with the same deasphaltingagent and at nosacrifice'in yield. Onthe other hand,vby using a novel modifierin conjunction with a known deasphalting agent, the deasphalting. operation can. be carriedout in such a manner as to produce a higher yield of deasphalted oil than can be obtained with the same charge stock using the some deasphalting agent alone and at. no sacrifice in, quality;

The novel modifiers are a special class -of the group, organic esters; towit: the carbonate of aliphatic, cycloaliphatic, and aromatic hydrocarbon and heterocyclic. compounds. The most readily available and; for. practical reasons, the prefered esters are methyl and ethyl carbonate. (CH3O)2CO- and (C2H5O)2CO respectively. Typicaliof the other modifiers are the carbonate of cyclohexane,. (CtH'nOYzCO, and the carbonates of fura'n, pyrrole and thiophene conforming. to the general formula; (ROMCO where R? is the monovalent residue of an: aliphatic; or: cyclealiphatic, or aromatic hydrocarbons oraheterm cyclic" compound provide an improved deasphalting agent for use in deasphalting mixtures of hydrocarbons and particularly for use in deasphalting residual mineral oils. The present invention has as an- 4 second, the raflinate is much heavier, i. e. the rafiinate had a viscosity of 135.1 seconds at 210 degrees Fahrenheit as compared with 99.9 seconds for the rafiinate when propane without a other object to provide a deasphalting agent 5 modifier was the deasphalting agent. On the which, in known processes, will produce the same other hand, when propane without a modifier quantityof lighter colored deasphalted oil having was used as the deasphalting agent (tests 1 and a lower carbon residue than deasphalted oil 2) and the tower temperatures controlled to proprepared by conventional deasphalting. The duce substantially the same yield of rafiinate the present invention has as a further object to procolor of the rafiinate was much darker, 115 as vide a deasphalting agent which, in known procompared with 62, and the viscosity significantly cesses, will produce a larger quantity of higher lower. viscosity, lighter colored deasphalted oil of com- By comparing tests 1, 4 and 6, the efiect of an parable carbon residue to that prepared by conincrease in the concentration of modifier in the vo l do p a gn aqdi o al 16011 deasphalting mixture can be recognized. An int p n ve n s t n v de a d pha s crease in modifier concentration from 1.5 to 2.5 agent wh ch will retain high viscosity 011 conper cent results in an 11 per cent increase in yield. stituents in the raflinate phase whlch are 0 While the viscosity increases slightly, on the other many dlsqarded Wlth the asphalt m conventlonal hand, the carbon residue is the same (i. e. within deasphalting. 'the limit of error). In contrast, when an at- In general, deasphaltmg Procedur? 15 that tempt is made to obtain-a process yield equal to used inv-conventional deasphaltmgof 0115. For thagobtamed with 2.5 per cent modifier in a p s apphed to resldual 0115, th 011 1S deasphalting mixture by controlling tower temheated to a temperature at wh1ch the 011 is freely peratures, the yield can be equalled but at a fiuld, f 011 15 contacted a closed sacrifice of quality which cannot be tolerated. tem w1th the mlxture of deasphaltmg agentf anfi Tests and 5 establish the foregoing VWIIBQ FF- i f then z g wlth fg using a deasphalting mixture containing 2.5 per guantmes' i :7 5 g g 3 1 cent of a modifier, a process yield of 64.3,per cent 0 remove en o y ma an 8 Q was obtained. When'using propane without any phalt and solution of rafilnate 1n the mixture or i modifier, a substantially equal process yield of deasphaltmg agent andtmodlfier i??? and 63.6 per cent was obtained However the rafflremoved .from. the sys em. Two su1 a e sequences of operations are illustrated in the g gg zg g fg 3 2 1 233? g ggi g wg' u a Process Handbook of Petroleum Refiner (April, g a or of 430 as compared w1th 115 and. a carbon residue 1947) at pages 226 to 229. The mixture of deof 20 6 cent a c d t 1 0 t T t asphalting agent and modifier is used in the i 7 h S omrare per cen es ratio 1 to 15 parts by volume of mixture to 1 c0 t e foregomg' At'exacfly the a part by Volume of on. Preferably, the modifier process ylelcl the color of the rafiinate, obtained is used in amounts up to about 20 volume per using propane as the soledeasphaltmg agent-1s cent of the mixture. Greater amounts of modi- 40 as compared to 115 and carbon 9?- fier can be used but at the cost or diminishing 25% comparedto w 115mg de p altreturns. Preferably, ethyl carbonate (C2H50)2CO mg agent contammgizfi per cent of fi i is used in the range of 1 to 12 volume per cent (tests 4 and 7 Test No. -8 establishes these of the mixture. It is also preferred to use de- {nodlfiers f P 11590918 solve SP asphalting mixture-oil ratios of about 3:1 to 10:1 mg agent In gravlty Settlmg l p there by vo1ume fore, it is manifest, in view of the data presented In order to provide a comparison of the efiect in th foregoing tabulation, that a modifier-for of the novel deasphalting mixture and a prior the class described hereinbefore cooperates with art deasphalting agent, the following data are well known, conventional deasphalting agents'to t l t 5 form a deasphalting mixture which produces ref Table I TestNo 1 2 a- 5 6 7 "'s- Hydrocarbon mixture; Temperature: 1 7

Top or tower, "F 180 165 180 180 125 180 125 125-180 Bottom of tower, F 120 120 120 120 120 120 120 120 Volume ratio:

Deasphalting mixture to oil. 10.1521 10:1 10:1 10.25zl 10:1 8.5:1 8:1 8:1 Vol. per cent deasphalting agt 98.5 100 100 97.5 100 94.1 100 Vol. per cent modifier... 1. 5 2. 5 5.9 100 Rafiinate yield, vol. per cent 57. 8 55. 6 47. 5 64. 3 63. 6 70,9 64.9 s. U. v. at210" F.,seconds 135.1 125. 2 99.9 142.4 162.1 192.2 170 Color (Lovibond )4 cell). 62 115 45 115 430 350 625 Per cent carbon residue V 0.8 0.8 0.3 1,0 2,0 2, 2 m

i A residual oil having an S. U. V. at 210 F. of 1,058 seconds.

I No separation of ratllnate and asphalt even at low throughout. The carbonaceous material remained suspended in the oil-deasphaltingmixture. Y

sults unattainable by. the use of conven'tio deasphalting agents. That is to say, th euse' of the novel deasphaltingv mixtures, comprising a conventional deasphalting agent and amodifier selectedfrom thegroup consisting of car of, aliphatic,cycloaliphatic, and aromatiq carbons and heterocyclic compounds subs-tan 1y completely. miscible in all proportions conventional deasphalting agents makes it possi ble to produce the same process yield of rafiinate of better color, higher viscosity and lower carbon residue or a better process yield of raflinate of equivalent quality than can be obtained employi-n the tabulation. In all instances fine, granular,

tarry materials in the amount of 9-14 weight per cent could be separated by filtration but the mixture of oil and diethyl carbonate did not stratify into a raflinate layer and a liquid asphaltic layer ing conventional deasphalting agents as the sole in gravity separating operations. component of a deasphalting mixture. Typical of the treatment of other residua are A series of tests have further established that the data submitted hereinafter in Table II obthe use of a modifier vsuch as diethyl carbonate tained by treating a mixed base crude, in Table as the so'le component of a deasphaltin'g mixture 10 III obtained by treating a West Texas sweet in amounts of 500 to 800 Volumeper' cent of remixed base crude, and in Table IV obtained by sidual oil, 1. e. .(CzHsO-J'zCO: oil ratio of 5:1 to furfural refining after deasphalting of a mixed 8:1 does not materially afiect the results reported base crude:

Table II Processing Conditions-Deasb'hzilting: i

Propane, Per Cent Volume'on Oil Charge 00 800 I800 800 1,000 1,000 800 800. 600 600 methyl-Carbonate, Per Cent Volume on Oil Charge 60 35 Temperature, F Tower Top. Temperature, F Tower Botto Run Number. e

42. S 2, 205 2,910 3, 160 3, 920 '4, 830 5, 190 5, 250 5, 400 5, 660 7, 210 S. U. V. 210 'F. Seconds 1,058 121. 5 140. 5 148. 0 164. 8 186.8 193. 6 197.2 197. 9 207. 0 225.9 Viscosity Index 1 v 76 r 74 73 73 73. 74 73 75 68 Viscosity Gravity'oonstailt 210 0.007 0. 833 0.8 37 0. 837 O. 843 0. 846 0. 849 0.845 0. 848 0. 844 0. 850 Color, Levibond, 54" Cell 750 85 245 165 550 v 415 750 335 750 715 T Carbon Residue, Per CentWeight 0. 7 0.8 1.3 l. l 2. 2 .2. 2 2. 7 r 2. 5 3. 3 3. 4

Specific Gravity @60F. ('Pyc. 77FZ) 1.0361 1.0650 1.0552 1.0718 1.0691 1.0854 1.0690 1.0794 1.0711 1.0865 Penetration 77F. 24 0 0 4 0 0 4 0 R and B Melting Point, '"F. 141 203 167. 5 215 178 246 226 180 259 1 Raw residuum. I Dewaxed 'deasphalted oil.

Table III Processing Conditions-Dessphalting; Propane, Percent'Volume. on Oil Cherge 600 1,000 800 1,000 600 l, 000 l, 000 800 Diethyl Carbonate Percent volume on Oil Charge '25 50 75 r 50 Temperature, F, ower Top 180 180 0 180 200 125 200 Temperature, "F, Tower Bottom Yield, Per cent Vol V Deasphaiting. "Overall:

fBrocessing Step.-." Inspections:

Gravity, .A P. 1,- ma-- Specifie Gravity 60F. (Pyc @77F.) Penetration 77F Ring and Ball Melting Point, "F

Raw residuum. Dewaxed deasphalted oil.

Table IV Processing Conditions-Deasphalting:

Propane, Per Cent Volume Diethyl Carbonate, Per Cent Volume.v Temperature, "F2, Tower Top Temperature, F., Tower Bottom Run Number Furfural Extracti n:

Solvent, Per Cent Volume Temperature, F

Run Number Yields, Per Cent Vol. On Process: Deasphalting Extraction Dewaxing, Ultimate Overall:

On Process 0n Crude Proc ssing Step Gravity, A. P. I

Pour Point Fire Point, F. (CO K. V. 100 F. Centistokes K. V. 210 F. Centistokes.. S. U. V. 100 F. Seconds... 8. U. V. 611 210 F. Secondsw Viscosity Index Viscosity Gravity Constant Viscosity Gravity 210 F Color, Lovibond, 14 CelL Carbon Residue, P r Cent Weight..." Sulfur, Per Cent Weight Asphalt:

Specific Gravit (10 60 F Penetration 6:) 77 F Rina and Ball Melting Point, F

Furfural Extract:

Specific Gravity 60 F Processing Conditions-Deasphalting:

Propane, Per Cent Volume Diethyl Carbonate, Per Cent Vo1urne Temperature, F., Tower Top Temperature, F., Tower Bottom.. Run Number Furiural Extraction:

Solvent, Per Cent Volume Temperature, "F

b Yields; Per Cent Vol. On Process:

Dnasphaltinq Extraction Dewaxing, Ultimate Overall:

On Process OnCrude... Processing Step Gravity, A. P. I Gravity, Specific 60 F. Pour Point, Flash Point, F. (000). Fire Point, F. (COO) K. V. 100 F. Centistokes. K.'V. 210 F. Cent stokes V. 100 F. Seconds V. 210 F. Seconds" Viscosity Index Viscosity Gravity Constant Viscosity Gravity 210 F--. Color, Lovibond, 14 Cell .i Carbon Residue, Per Cent Weight Sulfur, Per Cent Weight Asphalt:

Specific Gravity 60 F Penetration 77 F Ring and Ball Melting Point, "F Furfural Extract:

Specific Gravity 60 F .s

I Raw residuum.

i Waxy deasphalted oil.

3 Waxy Furfural Raifinate. 4 Dewaxed raiiinate.

I Finished oil.

Typical of the results produced by the use of the novel deasphalting mixture (deasphalting agent plus carbonates of aliphatic or cyclialiphatic, or aromatic, or heterocyolic hydrocarbons or mixtures or the:- foregoing) in the: deasphalting of a mixed base crude high. in. asphaltic materials, are; the data presented in Table V':

Table V Charge stock-Residuum from mixed base crude high in asphaltic materials Per cent volume of crude-16.4

Specific gravity 77/60 BE-019960 SLTIV. 210 F.-, seconds9l7' Carbonresidue, weight per cent-16.1

[DEASPHALTIN G1,

A B O Deasphalting Agent. percent vol 600 800 800 Modifier, percent vol 50 75 Temperature, F. to 125- 180 180 Temperature, F, bottom I20 I20 120 Deasphalted Oil:

Yield, percent vol 55.1 60. 66. 8 S. U. V. 210 F. seconds 156.0 165. 3 205 Color Lovibond 300 13 300' Conradson Carbon residue percent. wt. 2.2 2; 0 Ii 0; Asphalt:

Specific gravity. 1. 0739 l. 0864 110968 FURFURAL REFIN'IN'G' Percent vol. iuriural. f 200 200 200 Temperature, F 250 250 250 Waxy Railinate:

Yield.percent vol s..- f 71.4 68.0. 61. 3 S. U. V. 210 F. seconds 1'32. 6 136. 5 155. 3 Conradson Carbon residue percent wt. 0. B 0. 7 1. 0 Dewaxed Ratfinate:

Yield, percent vol 85. 4 86. 4 84. 3 S. U. V. 100 F. seconds. 2, 530 2, 670 3, 500 S. U. V. 210 F. seconds 151. 2 156.1 2. 5 Viscosity index 95 95 94 Conradson Carbon residue percent wt. 1. 0 0. 7 1. 1 Overall yield on charge percent vol. 33. 5 35. 6 34. 6 Overall yield on crude percent vol. 5. 50 5. 85 5. 68 Barrels of S. A. E. 30 (65 seconds 210 F. per 10,000 barrels of crude) Barrels bright stock 550 585 568 Barrels 150 100 F. (neutral) (43 210 F.) 572 033 694 Total Barrels S. A. E. 30 1,122 l, 218 l, 262

In other words, due to the high viscosity of the raifinate produced by deasphalting with the novel deasphalting mixture, between about 96 and about 140 barrels more of S. A. E. 30 motor oil can be produced from 10,000 barrels of this crude than can be obtained when deasphalting with conventional deasphalting agents. This represents an increased yield of S. A. E. 30 motor oil from this crude of from about 8.5 to about 12.5 per cent. When it is recalled that, at this time of short supply, low viscosity neutral oils are available in quantities far greater than the demand, the importance of the opportunity presented by the novel deasphalting mixture to balance the supplies of neutral oil and heavy lubricating fractions is recognized. In other words. the novel deasphalting mixture, due to the high viscosity of the finished oil, makes it possible for the refiner to use a greater portion (11 to 21 per cent more) of the low viscosity neutral oils of which there is a large excess in blending the lubricating oil fraction to an oil of predetermined viscosity such as S. A. E. 30.

As used hereinbefore and hereinafter in the claims, the term deasphalting agent includes within its scope those hydrocarbons, mixtures of hydrocarbons, organic compounds and the like which are known to those skilled in the art to function as diluents, or solvents for the nonasphaltic components of petroleum and the term deasphalting mixture includes within its scope deasphalted oil of given quality as measured by arequired Conradson carbon, residue of about 0.4

5 to about 6 weight per cent than can be obtained by conventional solvent deasphalting which comeprises contacting a fluid charge stock containing asphaltic material with a mixed deasphalting agent consisting essentially of. about 1, to about. 20 volume per cent of an organic carbonate and the. balancemajor deasphaltingv agent, deasphalting said charge stock at a deasphalting temperature above that temperature at Which parafiin. wax is substantially insoluble in said mixture of charge, stock and mixed deasphalt. ing agent. to about 206 F- and the nearer the required Conradson carbon residue is to 0.4 weight per cent the higher the deasphalting temperature in the presencev of a given concentration. of said organic carbonate, and separating adeasphalted oil having said required Conradson. carbon residue. in greater yield than can be obtained when deasphalting said charge stock to said required Conradson carbon residue. using, said. major deasphalting, agent as the sole deasphalting agent.

2. The method as: set. forth and described in claim 1. wherein the organic carbonate. is diethyl carbonate.

The method as. set. forth and described in claim 1 wherein the major deasphalting agent is liquid normally gaseous hydrocarbon.

4. The invention as set forth and described in claim 1 wherein the major deasphalting agent is propane.

5. A method of producing a greater yield of deasphalted oil of given quality as measured by a Conradson carbon residue of about 0.3 to about 4 weight per cent than can be obtained by deasphalting a given charge stock with propane as the sole deasphalting agent at deasphalting temperatures of 125 F. to 160 F. which comprises contacting a fluid charge stock containing asphaltic material with a mixed deasphalting agent consisting essentially of about 1 to about 6 volume per cent of diethyl carbonate and the balance propane, deasphalting said charge stock at a deasphalting temperature of about 165 to about 206 F. and the nearer the required Conradson carbon residue of the deasphalted oil is to 0.3 weight per cent the higher the deasphalting temperature and the lower the concentrathe mixture of one or more of said deasphalting tion of diethyl carbonate, and separating a deasphalted oil having said required Conradson carbon residue in greater yield than can be obtained when deasphalting said charge stock to said required Conradson carbon residue using said propane as the sole deasphalting agent.

6. A method of producing a greater yield of deasphalted oil of given quality as measured by a required Conradson carbon residue of about 0.4 to about 6 weight per cent than can be obtained by conventional solvent deasphalting which comprises contacting a fluid charge stock containing asphaltic material with a mixed deasphalting agent consisting essentially of about 1 to about 20 volume per cent of an organic carbonate and the balance major deasphalting agent in the ratio of about 1 to about 15 parts by volume of said mixed deasphalting agent to about 1: part by volume of charge stock, deasphalting said charge stock at a deasphalting temperature above that temperature at which paraflin wax is substantially insoluble in said mixture of charge stock and mixed deasphalting 11. agent to about 206 F. and the nearer the required Conradson carbon residue is to 0.4 weight per cent the higher the deasphalting temperature in the presence of a given concentration of said organic carbonate, and separating a deasphalted oil having said required Conradson carbon residue in greater yield than can be obtained when deasphalting said charge stock to said required Conradson carbon residue using said major deasphalting agent as the sole deasphalting agent.

7. The method as set forth and described in claim 6 wherein the organic carbonate is diethyl carbonate.

8. The method as set forth and described inclaim 6 wherein the major deasphalting agent is liquid normally gaseous hydrocarbon.

9. The invention as set forth and described in claim 6 wherein the major deasphalting agent is propane.

10. A method of producing a greater yield of deasphalted oil of given quality as measured by a Conradson carbon residue of about 0.3 to about 4 weight per cent than'can be obtained by deasphalting a given charge stock with propane as the sole deasphalting agent at deasphalting temperatures of 125 F. to 160 F. which comprises contacting a fluid charge stock containing asphaltic material with a mixed deasphalting agent consisting essentially of about 1 to about 6 volume per cent of diethyl carbonate and the balance propane in the ratio of about 1 to about 15 parts by volume of said mixed deasphalting agent to about 1 part by volume of said charge stock, deasphalting said charge stock at a deasphalting temperature of about 165 to about 206 F. and and nearer the required Conradson carbon residue of the deasphalted oil is to 0.3 weight per cent the higher the deasphalting temperature and the lower the concentration of diethyl carbonate, and separating a deasphalted oil naving said required Conradson carbon residue in-greater yield than can be obtained when deasphalting said charge stock to said required Conradson carbon residue using said propane as the sole deasphalting agent.

I HAROLD C. MYERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain July 11, 1934

Claims (1)

1. A METHOD OF PRODUCING A GREATER YIELD OF DEASPHALTED OIL OF GIVEN QUALITY AS MEASURED BY A REQUIRED CONRADSON CARBON RESIDUE OF ABOUT 0.4 TO ABOUT 6 WEIGHT PER CENT THAN CAN BE OBTAINED BY CONVENTIONAL SOLVENT DEASPHALTING WHICH COMPRISES CONTACTING A FLUID CHARGE STOCK CONTAINING ASPHALTIC MATERIAL WITH A MIXED DEASPHALTING AGENT CONSISTING ESSENTIALLY OF ABOUT 1 TO ABOUT 20 VOLUME PER CENT OF AN ORGANIC CARBONATE AND THE BALANCE MAJOR DEASPHALTING AGENT, DEASPHALTING SAID CHARGE STOCK AT A DEASPHALTING TEMPERATURE ABOVE THAT TEMPERATURE AT WHICH PARAFFIN WAX IS SUBSTANTIALLY INSOLUBLE IN SAID MIXTURE OF CHARGE STOCK AND MIXED DEASPHALTING AGENT TO ABOUT 206* F. AND THE NEARER THE REQUIRED CONRADSON CARBON RESIDUE IS TO 0.4 WEIGHT PER CENT THE HIGHER THE DEASPHALTING TEMPERATURE IN THE PRESENCE OF A GIVEN CONCENTRATION OF SAID ORGANIC CARBONATE, AND SEPARATING A DEASPHALTED OIL HAVING SAID REQUIRED CONRADSON CARBON RESIDUE IN GREATER YIELD THAN CAN BE OBTAINED WHEN DEASPHALTING SAID CHARGE STOCK TO SAID REQUIRED CONRADSON CARBON RESIDUE USING SAID MAJOR DEASPHALTING AGENT AS THE SOLE DEASPHALTING AGENT.