US2768121A - Treatment of hydrocarbons with iodine and/or hydrogen iodide followed by hydrogenation - Google Patents

Description

Oct. 23, 1956 IODIDE FOLLOWE l. BENTON l-:T Al. 2, TREATMENT oF HYDROCARBONS WITH 10mm: AND/0R HYDROGEN D BY HYDROGENATTON Filed Nov. 18, 1954 ATTORNEY nitecl States Patent 'I'REATMENT oF HYDRocARBoNs IonlNE AND/R HYDROGEN rompa FoLLowED BY HYDRoGENArIoN William I. Denton, Cheshire, Conn.,and William E. Garwood, Haddoniield, and Joseph N. Miale,V Woodbury, N. J., assignors to Socony Mobil Oil Company, Inc.,

a corporation of New York Application November V18, 1954, Serial No. 469,654

6 Claims. (Cl. 196-24) This invention relates to treatment of low grade ,Sulfurcontaining hydrocarbon oils. More particularly, .the

lpresent invention is directed to a process for Yconverting and upgrading hydrocarbon oils of high sulfur, nitrogen, or metal content. The process described herein A.is especially applicable `for treatment of residues and `tars .pro-

duced in various petroleum refining operations. These materials, which are normally disposed of ,as Notv oil, traditionally yield a very poor return in comparison 4with that obtained from gasoline and light gas `oils. t

The presence of sulfur, nitrogen, and heavymetals in petroleum crudes and fractions thereof `has l,heretofore been recognized as undesirable. `Sulfur occurs in petroleum stocks generally in `two principal forms,` asmercapremoval of refractory sulfur compounds of the Vringtype has been much more difficult. These compounds, as is well known, are highly objectionable in hydrocarbon oils because of their badodor and corrosive tendencies. u p

Thepresence of nitrogen compounds inA hydrocarbon .oilsis also objectionable since they tend to destroyvthe activity of hydrocarbon conversion catalysts withn 1the oil may be brought into contact duringvariousprocessing operations. Thus, in catalytic cracking A,.of,av'lryhjo-I carbon oil containing an appreciableamount of nitrogen compounds, the catalyst prematurely loses activity due .to the poisoning effects of the nitrogen compounds.

Likewise, the presence of metals and metal compounds, such as those of copper, vanadium,V nickel, and. ironin crude petroleum and various fractions thereof ishighly undesirable since they impart corrosive properties to the oil, contribute to ash deposition in fueloils and maregresponsible for catalyst deterioration when oils Ycontaining :the same are used asV charging stocks in catalytic cracking operations.

-Qne method for upgradingand removingsulfurpand other contaminants from hydrocarbon stockshas ,been byfhydrogenation in thepre'sence of `a sulfur-resistant catalyst at elevated `temperature and pressure-,whereby organic sulfur compounds present in the-,hydrocarbon Lcharge `are-,hydrogenatedrto hydrogensulde which is thereafter removed from the` treated hydrocarbons. Such Vprocedures `have generally involved-a considerablecon- -sumption of hydrogen, andthe costof supplying Athe hydrogen is an important factor influencing the economics of the process. In addition, in order to secureithe` reg quired partial',pressure of` hydrogen, it hasgenerallybeen essential vto operate l-at elevated` pressure, i.` e 43000 p. s."i. Vgrand higher, ,necessitatingthefnse of relatively ,expensive steels Yin y,plant construction which, inl turn. irnposes; a 4further..ecoxfiomic `burden-o'ntheprocess. Morever, while the above process has been employed with lll 2,758,121 Patented Oct. 23, 1956 some success in treating low and medium boiling petro= leum fractions, the process is totally unsatisfactory for sulfur removal from high boiling stocks, such as reduced crudes, cycle stock, cracking tars, shale oil, tar' sands, and residua. These latter stocks are characterized by the formation of an appreciable quantity of carbonaceous material on the catalyst after a short on-stream period rendering the catalyst inactive. Since regeneration is eX- pensive and since the period of activity is short, this .process has not been commercially attractive.

It is accordingly an object of the present invention to provide an improved method for upgrading low grade crude oils contaminated with appreciable quantities of sulfur, nitrogen, and/ or metals. A further object is the provision of an inexpensive method for upgrading heavy stocks such as residua. A still further Objectis to provide a commercially attractive combined process involving upgrading of low grade crude petroleum oils and treatment of heavy residua.

The above and other objects which will be apparent to those skilled ,in the art are achieved in accordance with .the present invention. Broadly, the process described herein comprises treating hydrocarbon oils containing sulfur, .nitrogen or metals with iodine, hydriodic acid or mixtures thereof at a moderately elevated temperature `below thatat which appreciable cracking of the hydrocarbon charge stock to `lighter material is encountered,

'separating the resulting upgraded productsl from an iodinerichtar containing the contaminantaby fractionation, to yield desulfurized gasoline, a gasoil low in sulfur and nitrogeniand free of metals, and a residuumcontaining small amounts of iodine. Such residuum may be treated directly with hydrogen Without further additionV of catalyst if the iodine content thereof exceeds 0.1 percent by weight. Theabove residuum is generally treated with vhydrogen `in the presence of a catalyst which is the aforementioned tar or iodine regenerated from said tar. As a charge to the second stage of treatment involving hydrogenolysis, the residuum obtained from the first stage may be' supplemented by additional petroleum residua from other sources. Such residua refers to the bottoms product afterpetroleum stock has been topped and the gas oil removed, i. e., that fraction boiling above 750 F. at

atmosphericrpressure. `These residua are ordinarily of little value per se because of their high content of sulfur and ash ,and their high tendency to coke on heating. The process of the instant invention thus provides a cornbined process involving the upgrading of low grade crudes or other stocks Which respond poorly to conventional refinery operations Iand the hydrogenolysis of refinery residuum, including cracking tars and other high boiling vheavy stocks.

It has been discovered, in accordance with the present invention, that iodine, hydriodic acid, and mixtures there- .of under particularly defined reaction conditions herein- .after set forth provide a highly efficient and selective means for effecting removal of sulfur, nitrogen, and heavy metal contaminants from hyrocarbon oils containing the same. It is contemplated that sulfur-containing hydrocarbon oils generally may be treated in accordance with .the instant process. Thus, petroleum crudes, gas oils, and

Areduced crudes containing sulfur are eirfectively refined lwith resulting` resulfurization and reduction in nitrogen Vand metal content. The process is particularly applicable .movedfrom the hydrocarbon stocks undergoing the the treatment described herein.

2,768,121 'e Y f I Thus, the first step of the process involves contacting a petroleum crude or similar stock high in sulfur, nitrogen, and metal content with iodine, hydriodic acid, or a mixture of iodine and hydriodic acid. The treating reagent may be brought into contact with the charge in any suitable manner. Advantageously, iodine is added as a solid while hydriodic acid is used as an aqueous solution although it may be used as a solution in a low molecular weight alcohol or other solvent. It is particularly desirable to employ aqueous constant boiling hydriodic acid containing about 55 percent HI. The temperature in the first stage of treatment should be maintained within the approximate range of 500 F. to 850 F. Below about 500 F., substantially no refining action takes place, while at temperatures in excess of 850 F., appreciable cracking or degradation of the hydrocarbon stock takes place, resulting in a lower liquid recovery and higher gas-make with little additional refining. In particular, it is desirable to employ a temperature between about 700 F. and about 800 F. The pressure may vary widely, depending upon the particular oil stock undergoing treatment and the temperature used but, in general, will be within the range of about 100 to about 3000 p. s. i. g. The time of reaction is dependent largely on the particular temperature employed and may range from 0.01 to hours, longer reaction times being employed with the use of lower temperatures. It is particularly feasible to operate in a continuous manner and in such instances a space velocity of about 0.2 to about 4 is employed.

The amount of iodine, hydriodic acid or mixtures thereof required for refining of the oil charge depends largely on the extent of contamination. It is usually advantageous to use an excess of reagent and to recover the unused portion thereof, followed by recyling. The amount of reagent, i. e., iodine or hydriodic acid, employed is generally between about 0.1 and about 30 percent by weight, and preferably between about 1 and about percent by weight, of the oil undergoing treatment. Solutions of iodine in hydriodic acid may also be used with advantage in the present process. Under such conditions of operation, the concentration of iodine in 55 percent aqueous hydriodic acid solution is preferably between about 40 and about 60 percent by weight. With the use of iodine, the presence of hydrogen in the reaction mixture was found to increase liquid recovery and to increase the extent of refining. Under such conditions of operation, it is desirable to employ hydrogen, preferably between about 100 and about 3000 p. s. i. g. pressure.

The products resulting from the above treatment cornprise gases, the treated liquid hydrocarbon product, and a tarry precipitate. The latter tar, containing the major portion of sulfur, nitrogen, and metals of the charge stock, also contains the iodine. This tar may alternatively be recycled as the catalyst in the above step, employed as the catalyst in the hydrogenolysis step described below, or burned to recover iodine and the trace metals contained therein. The treated liquid hydrocarbon product is fractionated to yield desulfurized gasoline, a gas oil low in sulfur and nitrogen and free of metals and a residuum containing small quantities of iodine which is treated in the second stage of the operation. The gaseous reaction product contains a substantial proportion of light hydrocarbons which may be collected for use as a fuel gas.

The second stage involves hydrogenolysis of the residuum obtained in the first stage either alone or in admixture with additional straight run residua from another source. As a catalyst for the second stage, the iodinerich tar from the first stage or regenerated iodine from such tar is employed. The amount of iodine-rich tar employed is generally between about 0.5 and about 25 percent by weight of the residuum charge. In those instances where regenerated iodine is employed, the amount thereof is ordinarily between about 0.1 and about 5.0 percent by weight of the residuum charge. A minor amount of coke, which is burned to recover iodine, is formed in the second stage, in addition to gasoline, gas oil, and unconverted residuum. The reaction conditions during hydrogenolysis involve a temperature in the approximate range of 750 F. to 1000L7 F., and preferably between about 800 and about 950 F., a pressure in the approximate range of 200 to 3000 p. s. i. g., and pref,-

erably between about 500 and about 1500 p. s. i. g., and a space velocity of between about 1 and about 10.

The operation may be carried out batch-wise by thoroughly mixing the oil charge with the hydriodic acid or iodine reagent under the above-specified conditions in the iirst stage and fractionating the resulting upgraded product to useful products and a residuum, and recovering the resulting iodine-rich tar. The residuum so obtained may thereafter be subjected to hydrogenolysis in the presence of the aforementioned tar as a catalyst.

The operation may also be carried out continuously as by passing the oil charge and reagent into a reactor and heating under the desired conditions of temperature, pressure and time. The resulting mixture of iodinecontaining tar, upgarded liquid products and gas is thereafter continuously separated. The upgraded product is fractionated to yield useful products and the residuum remaining is conducted to a hydrogenolysis unit where it undergoes hydrogenation in the presence of iodine which may inherently be contained in the residuum or added thereto as the aforementioned iodine-containing tar or iodine recovered therefrom.

Apparatus suitable for such an operation is illustrated diagrammatically in the appended drawing. Referring more particularly to the drawing, a hydrocarbon stock of high sulfur, nitrogen or metals content is pumped through conduit 1 and mixed with hydrogen, when desired, from conduit 2 and catalyst from conduit 3 before entering upgrading unit 4. The catalyst may be fresh aqueous HI or I2 pumped through line 24 or recycle catalyst, hereinafter described, pumped through line 25. The preferable reaction conditions in the upgrading unit are: temperature 700-800 F., pressure 100-3000 p. s. i. g. and space velocity 0.2-4. Reaction product from the upgrading unit passes through conduit 5 to high pressure phase separator 6. A heat exchanger, not shown, between vessels 4 and 6 may be desirably installed to cool the product. Gases from phase separator 6 are directed through line 7 into gas absorber 8 and any hydrogen contained therein is conducted through line 9 where it is met with make-up hydrogen from line 10 and compressed to -3000 p. s. i. g. before being recycled through upgrading unit 4. Liquid product from phase separator 6 is passed through line 11 to fractionator 12, along with the saturated absorber oil from line 13. Gasoline and gas oil separated in fractionator 12 are removed through lines 35 and 36, respectively. Tar from phase separator 6, containing approximately 2040% iodine, is removed through line 14 and may optionally be directed through line 15 for recycling to crude upgrading unit 4, through line 16 to iodine recovery furnace 17, or through line 18 for use as catalyst in hydrogenolysis unit 19. The choice is dependent upon several factors, such as the amount of residuum being charged to the hydrogenolysis unit, and the accumulation of tar in the upgrading unit. Under normal operations, at least a portion of the tar will be directed through conduit 16 to iodine recovery furnace 17. Regenerated iodine from furnace 17 may be passed through line 20 for use in upgrading unit 4 or through line 21 for use in hydrogenolysis unit 19. Ash from furnace 17, containing a high concentration of the trace metals, such as nickel and vanadium, is removed through conduit 22.

In the second phase of the process, virgin residuum or other heavy stock is pumped through line 23 to hydrogenolysis unit 19, along with hydrogen from line 26, and fresh HI or I2 from line 27 or recycle catalyst consisting of the tar produced in the above-described first stage conducted through line 40. The preferred raction edndition's in Vthe hydrogenolysis kunit: are: temperature 80G-950 F., pressure SOO-1500 p, s. i. g. andspace velocity` 1-'10. Product from hydrogenlysis unit 19 passes through line 29 to high pressure phase separator 30'. A leat exchanger,V not shown, between vessels 19 and 30 may be desirably installed to cool the product.

Gases from phase separator 30 are `vented through line y 3l.V to gas absorber 8. Liquid product, containing suspended coke, is passed through line 32 to fractionator 37. Unconve'rted residuum and coke separated in fractionator 37 are recycled through line 34 to hydrogenolysis unit 19, with a portion being conducted to iodine recovery furnace 17 through line 33. Gasoline and gas oil are removed from the fractionator through lines 38 and 39, respectively. If the gasoline and gas oil are high in sulfur and nitrogen, which will depend on the residuum charged, the liquid product from phase separator' 30 may be processed through upgrading unit 4. Further processing of the gasoline and gas oil fractions, if desired or war* ranted, may be done in conventional equipment, such as stabilizers, reformers, caustic scrnbbers, and catalytic cracking units.

n, The two stages of the above-described process are complementary and are more eiiciently applied than the sum of the two steps separately, since (1) the residuum from thel first step contains a catalytic amount of iodine, (2)

the tar from the first step can be used as a catalyst in A the second step and (3) only one unit for purification and pressuring of hydrogen and (4) only oneunit for catalyst recovery are necessary. The combined process also affords considerable exibility. Thus, a refinery handling a relatively small amount of high sulfur, high nitrogen crudes could upgrade such crude in the" first step and accumulate enough catalytic tar for the hydrogenolysis of a large quantity of residuum obtained from the reinerys low sulfur, low nitrogen crudesr On the other hand, should the economics at a giventime favor the use of residuum as fuel oil, the hydrogeno'lysis step would be used only on the residuum from the upgrading i, step and the catalytic tar from the upgrading step would be recycled or regenerated and the recovered iodine recycled.

The waning action obtained with the use of hydriodic acid, iodine, or solutions of iodine in hydriodic acid'inaccordance with the present process is unique in its effec'- tiveness in comparison with the extent of refining o'btained with other halides or hydrogenhalide solutions.

Thus, in comparable runs, aqueous HBr' desulfurized a hydrocarbon stock 9 percent and aqueous HCl 28 percent `under conditions at which aqueous HI `desulfu'rized the identical stock 73 percent. The use of hydriodic acid for refining under conditions of the present inventionaccordingly provides an unexpectedly high selective removal tof contaminant than either hydrofluoric or hydrochloric acid. In contrast to the present process, treatment of sulfur-containing stocks with HF, for example, throws out asphaltic materials which are higher in sulfur content than the balance of the stock and thus desulfurizes only in proportion to the amount of asphalt and sulfur content of the asphalt. Accordingly, with HF, poor yields and poor selectivity result while treatment with hydriodic acid or iodine in accordance with the above-described process affords high yields and good selectivity.

The following example will serve to illustrate the process of the invention without limiting the same:

A charge of crude oil contaminated with sulfur, nitrogen, and heavy metals is introduced to a stainless steel bomb together with approximately pounds HI (as aqueous solution) per barrel (315 pounds) of crude. Heat is applied and the temperature held at 700 F. for 2 hours, maximum pressure being 1400 p. s. i. g. At the end of ythis period, the heat is turned ot and the bomb allowed to cool to room temperature.

After Treat Crudel Charge V ol. percent recovery (including light ends) Wt. percent of hydrocarbon chg. t0 dry gas. Wt. percent of hydrocarbon chg. to sollds Wholcl uid product:

Speciflcgrayity API gravity Bromine No Carbon residue (Conradson) Percent Sulfur. Percent N itrcgen. Nickely p. p. 1n Vanadium, p. p. m.. Iron, p. p. In. Fractionated Product:

Gasoline (410F.), vol. percent liquid product.

Specic gravity. API gravity Percent Sulfur. Percent Nitrogen. Percent Iodine Nil Gas Oil (410-750F.), vol. percent: liquid product Specific gravity- A PI gravity Bromine No Aniline No., F Percent ,Sulfuru Percent Nitrogen Percent Iodine. Rcsiduum (750"1` ),Y

-uct

perce YSpecific gravity at 77F- Percent vSulfur Percent Nitrogen Percent Iodine from Taviano; vi t 4 W t, percent of hydrocarbon charge. Percent Iodil1 The total tar is conducted to an iodine recovery furnace and burned in air, yielding approximately 0.6 ``w'ei,f.,"lit per cent of `ash based on the tar, which, according to emission spectrographic analysis, consists of major amounts (oyer 10% by weight) lof vanadium, nickel, and iron, and a minor amount (1-'10% by weight) ,of copper.

The iodine `recovered from the iodine recovery -fnrnace is used `as a catalyst in a 'hydrogenolysis u nit 'in the Vamount of `about 0.3 percent by weight of a charge `of the'r'esiduum obtained as described `above and boil- 'ing above about 750*s F. Hydrogen in theamount of 2200 cubic feet per barrel of charge is introduced. The 'reaction conditions involve a temperature of 850 F., a pressure of 1200 p. s. i. g. and a space velocity of 4.

The' resulting products of hydrogenolysis are separated iby vfractionation to yield 21 volume percent of 400 R -end point gasoline, `52 volnrne percent of 40G-750 F. gas oil, 28 volume `percent of residuumboiling above 750`F `Hydrogen consumption is 650 cubic feet per 'bar-rel,

excess th-ydogen being recycled. The residuum above 750 F. may likewise be recycled to yield additional gasoline and gas oil.

The end products of the process are thus gasoline, gas oil, and an ash high in trace metal content. The yield of gasoline and gas 4oil from low grade crudes and residua is high and the quality as concerns the presence of nonhydrocarbons is good.

We claim:

1. A process for upgrading a hydrocarbon oil containing sulfur, nitrogen, and heavy metal contaminant, which comprises contacting said oil at a temperature between about 500 and about 850 F. and a pressure between about and 3000 p. s. i. g. with a reagent selected from the group consisting of iodine, hydriodic acid, and mixtures thereof, effecting phase separation of the resulting gaseous, liquid and tarry products, fractionating said liquid product to yield gasoline, gas oil, and a residuum, contacting said residuum with hydrogen in the presence of the aforementioned tarry product at a temperature bevtween about 750-F. and about 1000* F. and a pressure between about 200 and about 3000 p. s. i. g., effecting phase separation of the products of such treatment into a gas and liquid, fractionatin'g said latter liquid to yield gasoline, gas oil, and a second residuum, and recycling said second residuum to further treatment with hydrogen as aforesaid.

2. A process for desulfurizing and upgrading a sulfur containing hydrocarbon oil, which comprises contacting said oil at a temperature between about 700 and about 800 F. and a pressure between about 100 and about 3000 p. s. i. g. with between about 0.1 and about 30 percent by weight of a reagent selected from the group consisting of iodine, hydriodic acid, and mixtures thereof, effecting phase separation of the resulting gaseous, liquid and tarry products, fractionating said liquid product to yield gasoline, lgas oil, and a residuum, contacting said residuum with hydrogen in the presence of at least a portion of the aforementioned tarry product at a temperature between about 800 and about 950 F. and a pressure between about 500 and about 1500 p. s. i. g., effecting phase separation of the products of such treatment into a gas and liquid, fractionating said latter liquid to yield gasoline, gas oil, and a second residuum, and recycling said second residuum to further treatment with hydrogen as aforesaid.

3. A process for upgrading low grade crude petroleum oil and treating a high boiling petroleum residuum, which comprises contacting said low grade crude petroleum oil at a temperature between about 500 and about 850 F. and a pressure between about 100 and about 3000 p. s. i. g. with about 0.1 to about 30 percent by weight of a reagent selected from the group consisting of iodine, hydriodic ;acid,"and mixtures thereof, effecting phase separation of the resulting gaseous, liquid an-d tarry products, fractionating said liquid product to yield gasoline, gas oil, and a residuum, mixing said residuum with other high boiling petroleum residuum, contacting the resulting residuum mixture with hydrogen .in the presence of between about 0.5 and about 25 percent by weight of the aforementioned tarry product at a temperature between about 750 F. and about 1000 F. and a pressure between about 200 and about 3000 p. s. i. g., effecting phase separation of the products of such treatment into a gas and liquid, fractionating said latter liquid to yield gasoline, gas oil, and a residuum, and recycling said residuum to further treatment with hydrogen as aforesaid.

4. A process for upgrading a low grade hydrocarbon oil, which comprises contacting said oil at a temperature between about 700 and about 800 F. and a pressure between about 100 and about 3000 p. s. i. g. with a reagent selected from the group consisting of iodine, hydriodic acid, and mixtures thereof, effecting phase separation of the resulting gaseous, liquid and iodine-rich tarry products, burning said tarry product to recover iodine therefrom, fractionating said liquid product to yield gasoline, gas

oil, and a residuum, contacting said residuum with hydrogen inthe presence of the aforementioned recovered iodine at a temperaturebetween about 800 and about 950 F. and a pressure between about 500 and about 1500 p. s. i. g.,.eecting phase' separation of the products of such treatment into a'gas and liquid, fractionating said latter liquid to yield gasoline, gas oil, and a second residuum, and recycling said second residuum to further treatment with hydrogen as aforesaid.

5. A process for desulfurizing and upgrading a sulfur containing hydrocarbon oil, which comprises contacting said -oil with hydrogen at a temperature between about 500 and about 850 F. and a pressure between about 100 and about 3000 p. s. i. g. with about 0.1 and about 30 percent by weight of iodine, effecting phase separation of the resulting gaseous, liquid and tarry products, removing hydrogen from said gaseous product, and recycling the same to further contact with said oil, fractionating said liquid product to yield gasoline, gas oil, and a residuum, contacting said residuum with hydrogen in the presence of the aforementioned tarry product at a temperature between about 750 F. amd about 1000o F. and a pressure between about 200 and about 3000 p. s. i. g., effecting phase separation of the products of such treatment into a gas and liquid, removing hydrogen from said gas product, and recycling such hydrogen to contact with the initial oil charge, fractionating the liquid product to yield gasoline, gas oil, and a residuum, and recycling said residuum for further treatment with said tarry product and hydrogen as aforesaid. I

6. A process for upgrading a low gradev hydrocarbon oil, which comprises contacting said oil at a temperature between about 500 and about 850 F. and a pressure between about and about 3000 p. s. i. g. with between about 0.1 and about 30 percent by weight of a reagent selected yfrom the group consisting of iodine, hydriodic acid and mixtures thereof, effecting phase separation of the resulting gaseous, liquid and iodine-rich tarry products, fractionating said liquid product to yield gasoline, gas oil, and a residuum containing atleast 0.1 percent by weight of iodine, contacting said residuum with hydrogen at a temperature between about 750 F. and l000 F. and a pressure between about 200 and about 3000 p. s. i. g., effecting phase separation of the products of such treatment into a gas and liquid, fractionating said later liquid to yield gasoline, gas oil, and a second residuum, and recycling said second residuum to further treat- Vment with hydrogen as aforesaid.

References Cited inthe le of this patent UNITED STATES PATENTS 74,756V Flowers et al. Feb. 25, l1868 1,541,243 Behm June 9, 1925 1,843,516 Obel'le Feb. 2, 1932 1,893,438 Oberle Jan. 3, 1933 2,116,061 DOI'l'Cr May 3, 1938

Claims (1)

1. A PROCESS FOR UPGRADING A HYDROCARBON OIL CONTAINING SULFUR, NITROGEN, AND HEAVY METAL CONTAMINANT, WHICH COMPRISES CONTACTING SAID OIL AT A TEMPERATURE BETWEEN ABOUT 500 AND ABOUT 850* F. AND A PRESSURE BETWEEN ABOUT 100 AND 3000 P.S.I.G. WITH A REAGENT SELECTED FROM THE GROUP CONSISTING OF IODINE, HYDRIOD ACID, AND MIXTURES THEREOF, EFFECTING PHASE SEPARATION OF THE RESULTING GASEOUS, LIQUID AND TARRY PRODUCTS, FRACTIONATING SAID LIQUID PRODUCT TO YIELD GASOLINE, GAS OIL, AN A RESIDUUM, CONTACTING SAID RESIDUUM WITH HYDROGEN IN THE PRESENCE OF THE AFOREMENTIONED TARRY PRODUCT AT A TEMPERATURE BETWEEN ABOUT 750* F. AND ABOUT 100*F. AND A PRESSURE BETWEEN ABOUT 200 AND ABOUT 300 P.S.I.G., EFFECTING PHASE SEPARTION OF THE PRODUCTS OF SUCH TREATMENT INTO A GAS AND LIQUID, FRACTIONATING SAID LATTER LIQUID TO YIELD GASOLINE, GAS OIL, AND A SECOND RESIDUUM, AND RECYCLING SAID SECOND OF FURTHER TREATMENT WITH HYDROGEN AS AFORESAID.

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