US2988501A - Hydrorefining of crude oils - Google Patents

Description

June 13, 1961 2,988,501

T. V. INWOOD HYDROREFINING OF CRUDE OILS Filed Aug. 18, 1958 2,983,501 p p HYDROREFINING F CRUDE OILS Texas V. Inwood, La Habra, Calif., assignorjto Union Oil Company of California, Los Angeles, Calif., a corporation of California Filed Aug. 18, 1958, Ser. No. 755,579 15 Claims. (Cl. 208-211) This invention relates to methods for the catalytic hydrorefning of crude oils, particularly crude shale oils for the elimination of organic sulfur, nitrogen, and oxygen compounds, gumand colorforming bodies, and the general upgrading thereof. In particular, the invention is concerned with methods for pretreating the feed oil whereby upon subsequent preheating and contacting with the hydrorefining catalyst, the normally occurring deposition of solid or semi-solid carbonaceous materials in the heater tubes, transfer lines, valves, and upper sections of the catalyst bed, is markedly reduced. IIn broad aspect, the invention consists in first mixing the raw feed oil with a recycle portion of the refined liquid product, or a selected fraction thereof, then allowing the mixture to settle by gravity or centrifuging to facilitate the separation of a heavy asphaltic phase, and then heating the asphalt-lean raffinate oil mixture to hydrorefining temperatures and contacting it with the catalyst under hydrorefining conditions. It is particularly preferred to recycle aportion of the product fraction boiling between aboutf350 'and 500 F., although any other fractions ofthefeed may also be included. It has been found that this 'pretreatment materially reduces the deposition of gums, tars, coke, and other carbonaceous deposits, which constitutes Ia serious problem in the catalytic treatment of crude oilsat elevated temperatures.

The principal objective of the invention therefore is to provide methods for contacting crude oils with hydrorefining catalysts in such manner as to minimize the deposition of carbonaceous deposits upon the catalyst, and in the preheater tubes, transfer lines,`valves, etc. Another Vobjective is to provide iiexible control means for reducing the pour-point of the final product to the desired degree. Still another object is to 'provide means'for remov- 'ing the deposit-forming constituents of crude oils, while maintaining maximum overall liquid yields. 'Another obiect is to avoid the added expense involved in separating 'from crude oil feedstocks such conventional 'deasphalting 'solvents as propane, butane, `light naphthas and the like. A specific object is to prolong the total life of the hydrorefinng catalyst, and to prolong the life cyclebetweenregenerations thereof. Other 'objects will be apparent from the "more detailed description which follows.

Feedstocks which may be treated hereini'nclude 'specifically crude shale oil, reduced crudeshale oil, petroleum crude oils, or reduced crudes, residual fractions from the topping of such crude oils, or mixtures 'of 'such materials. In addition mixtures of anyof the foregoing crude oils or residual 'fractions may 4be treated lin admixture with distillate fractions. For example, mixtures of crude oils with naphtha fractions, light or heavy lgas 4oils andthe like, are also contemplated.

The process of this invention is especially adapted for the treatment of crude shale oils, yi.e. the full-range oil produced directly fromthe retorting of shale-rock. Crude :shale oils Apresent difiicult problems in refining in that Ithey `contain a high proportion of asphaltenes and carfboidsyand up to about 4% of `nitrogen in the form of forg'anic nitrogen' compounds. In addition, 'metals may be `present in the lform of Vporphyrin-metal complexes or other Aorgano-metallic compounds. Crude f shale 'oils also some- 'times possesan unusually high pour-point. For example, "the crude oil from Colorado shale -is'no'rmally fa Jgeliat il; n

Patented June 13, 1961 ice room temperature, and its .pour-point may be in excess of 100 F.

The crude shale oil described herein may be produced Vfor example by the retorting procedures described in U.S. Patents 2,501,153, 2,640,015, and 2,640,019. In general, the retorting procedure consists in initiating combuston in a body of moving shale rock, and utilizing the hot combustion gases to educt the oil from uncombusted shale rock upstreamwardly from the combustion zone.

From the standpoint of refining flexibility and economy, the most desirable initial treatment for such oils consists of catalytic hydrorefining to decompose nitrogenous compounds and sulfur compounds, to hydrogenate asphaltenes and carboids, to decompose organo-metallic compounds, and in general to improve the color and handleability of the oil for subsequent refining procedures such as cracking, reforming, and the like. Such an initial treatment also increases the overall final yield of refined products, while at the same time substantially reducing corrosion problems throughout the subsequent refining treatment. The first major difiiculty encountered in attempting to hydrorefine such oils consists in the tendency of the oil to deposit carbonaceous solids upon hot surfaces in the preheating or catalyst-contacting zones. The exact nature of the deposit-forming constituents is not known, but they may comprise any of lthe above-noted organo-metallic components, asphaltenes, carboids, and/ or ntirogenous compounds.

The foregoing problems may be partially or completely solved by conventional pretreatment steps such as vacuum distillation, thermal coking, or liquid-phase deasphalting using lower parafns, but these treatments lead to other disadvantages. In all cases, the liquid yield of final product is relatively low, e.g. between about -85%. Moreover, it will be apparent that all of these procedures involve an additional step requiring expensive equipment and substantial operational costs. The process of this invention, however, does not involve any unusual added expense, and liquid yields in excess of 90% by volume are ordinarily obtained.

In the treatment of crude shale oil another problem encountered is the viscosity of the oil, which inhibits its ability to fiow freely in a pipeline. It is sometimes desirable, for reasons of economy, to transport the shale oil after a minimum of processing at the retorting site, to a more distant refinery for final treatment. The most economical form of transport is by pipeline, but this is practical only if the oil has a sufficiently low viscosity to flow freely during cold winter months. It is, therefore, desirable to reduce the pour-point of the crude oil during the initial refining steps and thereby reduce its viscosity, so that itmay be economically transported to amore favorably situated refining site. This usually involves reducing the pour-point from its initial -100 P. to about 2070 F.

A considerable degree of pour-point control is integrated into `theprocess of this invention. Thus, in the :preferred modification of the process, where `a portion of the heavy endsof the hydrorefined product is recycled with the fesh feed, each pass throughthe reactor will effect a further reduction in pour-point as a result of the hydrocracking of lhigh molecular weight paraflins inthe wax range. It would be undesirable'to attempt to effect .the desired pour-point reduction by a single pass through `the"rea`ctor, inasmuch as this would entail the use of `'high temperatures leading to reduction in liquid yields, rapid coking kof the catalyst, etc. These disadvantages are "largely avoided where the heavy fraction of feed, or 5a -portion thereof, is recycled through the reactor; in effect, `the heavy ends of the feed are subjected to treatment lat 'a low'ernetspace velocity than the light fractions, `thus Yprovidingamore selective hydrocracking of the `heavier 3 molecules. To obtain maximum reduction in pour-point, the recycled portion of product should include a maximum proportion of the heavy ends, while if only minimum pour-point reduction is desired it is preferable to recycle a lesser proportion of the heavy ends.

In the practice of this invention, it is feasible to recycle a portion of the full-range product, or a portion of the heavy ends thereof, or a portion of the mid-boiling-range materials boiling for example between about S50-500 F. Generally, regardless of the boiling-range of the fraction recycle, it is preferred to recycle between about 0.1 and 5 volumes thereof per volume of fresh feed. Best results are generally obtained when the recycle rate is between about 0.2 and 2.5 volumes of hydrogenated product per volume of fresh feed.

Though I do not wish to be limited by any theory as to the mechanism involved in the pretreatment process herein described, it is believed that more than one' factor may be involved. The principal effect is observed in a precipitation, or phase separation of heavier, more viscous, asphalt-like material. This phase separation is not always sharp in the sense that a sharply defined interface is formed, but upon mixing the oils and allowing them to settle, a distinct qualitative separation of heavier materials is noted. The completeness and rapidity of the separation is materially improved by maintaining the mixed oils at temperatures in excess of about 100 F., and preferably between about 14C-250 F.

The asphaltic material which settles from the oil mixture may be withdrawn by any conventional phase-separation technique, or if desired a sharper separation may be obtained by centrifuging. Where ordinary gravity settling is employed, it will normally not be possible to obtain a sharp separation of asphaltic materials by simple decantation, or withdrawal of the lower phase, unless very extended settling periods are employed. It is however an important feature of my invention that a quantitative phase separation is unnecessary, especially when using the preferred product fraction for recycle. This preferred fraction'should include a substantial proportion of material in the 350-500" F. boiling range.

This fraction includes a considerable proportion of partially hydrogenated, fused-ring aromatic hydrocarbons, e.g. tetralin and the like. These compounds materially aid in preventing the subsequent precipitation of coke, gums, and the like during preheating and hydrorefining, probably due to hydrogen transfer reactions. Thus, even through the initial separation of asphaltic components is not complete, the remaining minor amounts may be tolerated in the preheating `and hydrodening equipment due to the presence of tetralin-likc hydrocarbons in the recycled product, which effectively hydrogenate the coke precursors, thereby preventing the formation of gums, tars and coke.

The proportion of raw feed which is initially precipitated and removed as the asphalt-rich phase will usually comprise about 1-l0% by volume thereof. However, depending upon the amount and type of hydrogenated product which is recycled quantities outside this range may sometimes be separated. Also, where efficient separation is obtained, as e.g. with a centrifuge, the amount of asphalt-rich phase removed may sometimes be reduced to less than 1%. This asphalt-rich phase may be withdrawn and used in fuel oils, or it may be subjected to thermal coking, conventional solvent-deasphalting procedures or the like to recover therefrom an addition quantity of asphalt-free oil for hydroreining.

In the hydrorefining step, the pretreated, mixed feed is contacted with a suitable sulfactive hydroreiining catalyst under conditions of hydrorening. 'Ihe catalyst may be disposed in `a fixed stationary bed, or the various moving bed, or uidized bed techniques may be employed. Generally, the xed bed technique is most satisfactory. The catalyst may comprise any of the oxides and/or suldes of the transitional metals, and especially an oxide i M assessor or sulfide of a group VIII metal (particularly iron, cobalt or nickel) mixed with an oxide or sulde of a group VIB metal (preferably molybdenum or tungsten). Such catalysts may be employed in undiluted form, but preferably are distended and supported on an adsorbent carrier in proportions ranging between about 2% and 25% by-weight. Suitable carriers include in general the dicultly reducible inorganic oxides, e.g. alumina, silica, zirconia, titania, clays such as bauxite, bentonite, etc. Preferably the carrier should display little or no cracking activity, and hence highly acidic carriers are generally to be avoided. The preferred carrier is activated alumina, and especially activated alumina containing about 315% by weight of coprecipitated silica gel.

vThe preferred hydroreiining catalyst consists of cobalt oxide plus molybdenum oxide supported on silica-stabilized alumina. Compositions containing between about 2%and$% of C00, 4% and 20% of M003, 3% and 15% ,of .SiO2, and the balance A1203, and wherein the mole-ratio of COO/M003 is between about 0.2 and 4, are specifically preferred. These catalysts are preferably prepared by alternate impregnation with yaqueous solutionsjof `ammonium molybdate and cobalt nitrate, as described in U.S. Patent No. 2,687,381.

.Suitable hydrorening conditions are as follows:

Operative Preferred' 70D-850 A10G-3, 000 Y 1-10 50G-5, 000

Within the above operating conditions, the specific hydroreiining conditions selected should be such as to meet required product specifications.

The process of this invention will now be described in more detail in connection with the attached flow sheet1 which is intended merely to illustrate the principal modiffications, .but is not intended to be limiting in scope'. The initial feedstock is brought in through line 1 and preheated to the desired settling temperature in preheater 3, e.g. to about F. The preheated feed is then passed via line 5 into mixing valve 7 wherein it is mixed with the recycled hydrorened product, or frac'- tion thereof, from line 9. The mixture is then transferred via line 11 to a settling tank 13, wherein the mixture is allowed to stratify, at e.g. 150 F., for a suflicient length of time to obtain the desired separation. This time range is extremely variable, depending upon the characteristics of raw feed, amount and type of product recycle, and settling temperature, but ordinarily will range between about 2 lhours and 48 hours. 'Ihe asphalt-n'ch phase is withdrawn via line 15, and may be utilized for fuel oil via line 17. However, if desired, this material may be transferred via line 19 and preheater 21 to thermal coker 23. The coking step generally involves heating the asphalt-rich oil to a cracking ternperature of e.g. 750950 F. and then allowing it to soak in coker 23 for several minutes or hours while continuously removing overhead the volatile products boiling in the gas oil range and below, and continuously precipitating coke on the walls of the coking vessel. Ordinarily, none of the liquid feed is removed as liquid, all being converted to coke, light gases, or distillates.

yEventually the coke which precipitates in coker Z3 will fill the vessel, and somewhat before this point is reached the operation must be suspended while the coke is removed. As the coke precepitates it adheres to the walls and becomes strongly agglomerated into a dense hard mass. This mass is ordinarily removed either by drilling out the drum, or by washing it out with highpressure jets of water. While this operation is proceeding, ,the flow of oil in line 19 is diverted to another col;-

e.. n may.

The overhead product from coker 23 is transferred via v line 25 to line 27, where vit `is mingled with the principal feed stream for hydrorelning as subsequently described.

The puritied oil in separator 13 is continuously or intermittenly withdrawn via line 29 and passed via pump 3,1, line 27, preheater 33, and line 35 into the top of 'reactor 37, wherein hydrorening takes place under the conditions previously described. Recycle and makeup hydrogen for the hydrorefining reaction may be blended with the feed, either through line 39 ahead of preheater 33, or it may be separately preheated in heater 41 and admitted via line 43.

The total effluent from hydrorener 37 is withdrawn via line 45, cooled to e.g. ISO-250 F. in condenser 47 and transferred via line V49* to high-pressure separator (51.v Where crude shale oil is being treated, it is usually desirable to introduce a small amount of ywater or steam via line 53, which is condensed in condenser 47 and elfects a scrubbing of the total product to remove therefrom soluble salts such as ammonium chloride and ammonium sultides.

The waste wash water is withdrawn from separator 511 via line 55. Hydrogen-rich recycle gas is taken off via line 57, blended with makeup hydrogen from line 59, .and the mixture is then recycled via compressor 61 into line 63 for use as previously described.

The liquid hydrocarbon product in separator -1 is withdrawn via line 65 and flashed into low-pressure sepavrator vessel 67 from which hydrogen-lean light gases containing methane, ethane, and the like, may be withdrawn 'via line 69 and utilized as fuel gas or the like. The iinal liquid product is withdrawn via line 71, and if a portion ,of the full-range product is to be used for recycle, this portion is diverted through line 73` and recycled to mixing valve 7, via line 9. The net product in this case is recovered via lines 75'-, 83 and 81. If a selected fraction of the feed is to be used `for recycle, the entire liquid product is passed into line 75 and transferred in whole or in part to distillation column 77 via line 79. Any portion of the liquid product which is not subjected to fractionation is passed directly into final product recovery line 81 Vvia line 83.

In fractionating column 77 a light overhead is ordinarily taken overhead and condensed in cooler 85- to mix with the final product in line 8.1. Where a full-range bottoms fraction is to be utilized for recycle, the total bottoms from column 77 is withdrawn via line 87, and is split into a net product fraction in line 89 and a recycle portion passing to mixing valve 7 via lines 911, 93, and 9. This full-range bottoms fraction is preferably the 350 R+ fraction.

Where it is desired to utilize only a mid-boiling-range portion of product for recycle, line 95 may be utilized to withdraw from one or more trays of the column a fraction boiling e.g. between about 350 and 500 F. Any selected cut within this range, or the entire range, may be utilized. This fraction may then be split into a net product fraction going to product recovery line 81 via line 97, and a recycle portion passing to mixing valve 7 via lines 99, 93 and 9. In the event that only the side-cut is utilized for recycle, then the 500 F-ibottoms fraction removed via line 87 is preferably passed entirely via line 89 to product recovery line 811.

While it has been indicated that the overhead fraction boiling below about 350 F. is not recycled, it is not intended to preclude the recycling of part of this material along with either the heavy ends or the side-cut fraction which is recycled. It will be apparent that many other modications of the specific operations above `describedmay be employed 'without departing from the eslimiting -in scope.

Example A crude shale oil educted from Colorado shale rock, said oil having a 50% boiling point of 680 F., a gravity of 20.4 API, containing 1.84 Weight-percent nitrogen, and vhaving a Ramsbottom carbon residue of 3 weightpercent, was subjected to conventional hydroreiining using a catalyst consisting of 3 weight-percent COO and 9 weightpercent MoO3,-impregnated on a carrier consisting of A1O3 and 5% coprecipitated SiOZ. The conditions of hydroreiining were: pressure 3,000 p.s.i.g., liquid hourly space velocity 2.0, hydrogen/oil ratio 6,000 s.c.f./bbl`., and average temperature 735 F. After operating under these conditions for 35.5 hours, the pressure drop across the reactor had risen from about l inch of water to 27 inches, indicating that excessive plugging of the reactor had occurred. The operation was hence discontinued and it was found that the vcatalyst contained coke and gum deposits amounting to 0.06 weight-percent of the total feed processed. A portion of these depto-sits no doubt were initially formed in the preheater section of the reactor, and subsequently carried into the catalyst bed by the iiowing liquid feed.

*In another hydroreiining run, two parts of the crude shale oil and one part vby volume of the 400 F.-}- bottoms from the hydrogenated product were blended and allowed to settle for about 24 hours at 120 F. A considerable precipitation of heavy asphaltic material was noted, which precipitation does not occur when the raw feed alone is allowed to stand under the same conditions. Upon drawing off the supernatant mixture of raw crude oil and hydroreiined product, and subjecting the blend to hydrorening under the same conditions above described, it is found that the operation may be continued smoothly forA several weeks without excessive pressure drop across the reactor,-and without significant decline in catalyst activity. The final product is substantially completely desulfurized and about 70% denitrogenated, -while the pour-point (of the product reconstituted with the 0-400" F. fraction of the initial product) is 2-10 F. lower than that of the total product obtained by -hydroreining the untreated crude oil.

It is hence apparent that by blending the relatively hydrogen-rich product with the hydrogen-lean crude oil, and allowing the mixture to settle, a rconsiderable and effective portion of the materials leading to deposition of carbonaceous deposits causing plugging of the recator may be removed, while at the same time the product has a lower pour-point. This result may be obtained even though no more than 1-10% by volume of the raw feed is removed as the asphalt-rich phase.

The foregoing description of specific methods is not intended to be limiting in scope except where indicated. Many Variations will occur to those skilled in the art, and all such variations which yield essentially the same result are intended to be included. The true scope of the invention is intended to be embraced by the following claims:

I claim:

l. In a process wherein a relatively hydrogen-lean crude oil feedstock is subjected to catalytic hydroretning at elevated temperatures with consumption of hydrogen to produce a relatively hydrogen-lean rened liquid product, the improved method for reducing the deposition of solid carbonaceous matter in the hydroreiining zone, which comprises blending said feedstock with a recycled portion of said refined liquid product, said recycled portion boiling predominantly above about 350 F., then subjecting the resulting blend to settling conditions at a temperature in excess of 100 F. for a suicient length of time `to effect a liquid-liquid phase separation and separating (therefrom a minor, heavy asphalt-rich liquid phase and a major asphalt-lean liquid phase, heating said asphalt-lean phase to a hydrorefining temperature, and subjecting the heated oil to catalytic hydrorefining at a temperature between about 600 and 900 F. in the presence of added hydrogen.

2. A process as defined in claim l wherein said recycled 'portion of refined product comprises about 0.2 to 2.5 volumes per volume of fresh feedstock.

3. A process as defined in claim l wherein said recycled portion of refined product is a portion o'f the heavy fraction thereof boiling entirely above about 350 F.

4. A process as defined in claim 1 wherein said recycled portion of refined product is a portion of the mid-boilingrange fraction. thereof boilingbetween about 350 and 500 F.

5. A process as defined in claim 1 wherein said recycled portion of refined product is a full-boiling-range portion thereof.

6. A process as defined in claim 1 wherein said feedstock is a crude shale oil.

7. A process as defined invclaim 1 wherein the catalyst employed in said hydrorefining zone is essentially a com- -posite of cobalt oxide plus molybdenum oxide supported on a carrier which is essentially activated alumina.

8. In a process wherein a relatively hydrogen-lean crude oil feedstock is subjected to catalytic' hydrorefining at elevated temperatures with consumption of hydrogen lto produce a relatively hydrogen-lean refined liquid product, the improved method forreducing the deposition of `solid carbonaceous matter in the hydrorefining zone and vfor obtaining a controlled reduction inpour-point of said liquid product, which comprises blending said feedstock with a recycled portion of said refined liquid product, said recycled portion of product including a full-range bottoms fraction thereof having an initial boiling point in .excess of about 350 F., then subjecting the resulting blend to settling conditions at a temperature in excess of -l00 F. for a suicient length of time to effect a liquidliquid phase separation, and separating therefrom a minor heavy asphalt-rich liquid phase and a major asphalt-lean liquid phase, heating said asphalt-lean phase to a hydrorelining temperature, and subjecting the heated oil to catalytic hydrorefining at a temperature between about 600 and 900 F. in the presence of added hydrogen and at superatmospheric pressures. v

9. A process as dened in claim 8 wherein said recycled portion of refined product comprises about 0.2 to 2.5

volumes per volume of fresh feedstock.

10. A process as defined in claim 8 wherein saidrercycled portion of refined product is a portion of the heavy fraction thereof boiling entirely above about 350 F.

ll. A process as defined in claim 8 wherein said recycled portion of refined product is a full-boiling-range portion thereof.

12. A process as defined in claim 8 wherein said feedstock is a crude shale oil.

13. A process as defined in claim 8 wherein the catalyst employed in said hydroreiining zone is essentially a composite of cobalt oxide plus molybdenum oxide supported on a carrier which is essentially activated alumina.

14. A process as defined in claim 8 including the steps of subjecting said asphalt-rich phase to thermal coking to produce coke and a coker distillate, and blending the resulting coker distillate with said asphalt-lean phase for combined treatment in said hydrorening zone.

15. A method for converting a relatively hydrogen-lean crude shale oil to a refined product of reduced pourpoint suitable for use in the production of conventional petroleum-type products, which comprises blending said shale oil with a relatively hydrogen-rich recycle product fraction produced as hereinafter defined, subjecting the resulting blend to settling conditions at a temperature -above about F. for a sufficient length of time to effect a substantial stratication, separating from the settling zone a minor asphalt-rich liquid phase and a major asphalt-lean liquid phase, heating said asphalt-lean phase to vhydrorefining temperature, and subjecting the heated oil to catalytic hydrorefining at a temperature between about 600 and 900, F. in the presence of added hydro genY and at superatmospheric hydrogenating pressures, recovering a condensed liquid product from said hydrorefining, dividing said condensed liquid product into a net product portion and a recycle portion, subjecting said rccycle portion to fractional distillation to recover therefroman overhead fraction boiling below about 350 F. and a bottoms fraction boiling above about 350 F., dividing said bottoms fraction intova net bottoms product portion and said recycle product fraction, and recycling said recycle product fraction to said initial blending step.

References Cited in the le of this patent UNITED STATES PATENTS 2,606,141 Meyer Aug. s, 1942 FOREIGN PATENTS 362,458 Germany oct. 27, 1922 430,438 Germany June 16, 1926 UMTIJD STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent N0'. 2,988,501 June 13, 1961 Texas V, Inwood It is hereby certified that error appears in the above numbered petent requiring correction and that 'bhe said Letters Patent. should read as l-coI-Teoizec below.

Column 6, line 69, and column 7, line 3l, for "hydrogenlean", each occurrence, read hydrogen-rich Signed and sealed this 14th day of November 1961.

(SEAL.)v

Attest:

ERNEST W.SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC

Claims (1)

1. IN A PROCESS WHEREIN A RELATIVELY HYDROGEN-LEAN CRUDE OIL FEEDSTOCK IS SUBJECTED TO CATALYTIC HYDROREFINING AT ELEVATED TEMPERATURES WITH CONSUMPTION OF HYDROGEN TO PRODUCE A RELATIVELY HYDROGEN-LEAN REFINED LIQUID PRODUCT, THE IMPROVED METHOD FOR REDUCING THE DEPOSITION OF SOLID CARBONACEOUS MATTER IN THE HYDROREFINING ZONE, WHICH COMPRISES BLENDING SAID FEEDSTOCK WITH A RECYCLED PORTION OF SAID REFINED LIQUID PRODUCT, SAID RECYCLED PORTION BOILING PREDOMINANTLY ABOVE ABOUT 350*F., THEN SUBJECTING THE RESULTING BLEND TO SETTLING CONDITIONS AT A TEMPERATURE IN EXCESS OF 100*F. FOR A SUFFICIENT LENGTH OF TIME TO EFFECT A LIQUID-LIQUID PHASE SEPARATION AND SEPARATING THEREFROM A MINOR, HEAVY ASPHALT-RICH LIQUID PHASE AND A MAJOR ASPHALT-LEAN LIQUID PHASE, HEATING SAID ASPHALT-LEAN

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