US2853433A - Heavy oil conversion to gasoline - Google Patents

Description

Sept. 23, 1958 P. c. KEITH 2,853,433

` HEAVY OIL CONVERSION To GAsoLINE Filed Ju'ly 16, l195.22

#GENT States O 2,853,433 HEAVY on. CONVERSION To GAsomNr Percival C. Keith, Peapa'ck, N.r I., assignor to Hydrocarbon Research, Inc., New York, N. Y., a corporation of New Jersey Application July 16, 1952, Serial No. 299,178-

Claims. (Cl. 196-49) This invention relates to the productionV of highqality gasoline from hydrocarbon ils, and is more particularly concerned with a process for the eiiicient production of high quality gasoline from heavy oils, especially those which have a high content of sulfur, nitrogen or metal compounds.

At the present time, commercially acceptable motor gasoline has a sulfur contenty of notv greater than 0.3% by weight and preferably notV greater than 0.1%,fas measured in accordance with ASTM methods D129`491 and D90-47T. Specifications for commercial motor gasoline likewise require that it pass an existent gum test, in accordance with ASTM method D-'38'1, in which the gasoline' must show less thanS mg'. of gum per 100ml. In addition,- it is highly desirable that commercial motor gasoline meet the storage stability requirements set forth in ASTM method D910-48T or D52549. Finally, the demands of modern high compression engines make it necessary the production of motor gasoline possessing a high octane rating, usually determinedA as fclear research octane number inl accordance with ASTM` ,method D908.- 48T., Arithmetic averages in January, 1952, for motor gasoline sold in 45 U. S. cities indicate research octane ratings of 83.2 and 90.0` for regularf and premium gasolines, respectively, with sucligasolines'containing' an average of 1.35 and 1.75 cc./g'a'l., respectively, of tetraethyl lead'. I

In modern petroleum refining practice, itI is .highly advantageous to convert part or all of the higher Boiling fractions of the cr'de oilKto materials boiling in' the gasoline range. This is e'iecte'd byy processes which' in'- volve the cracking of the higher boiling hydrocarbons into hydrocarbons boiling in theV gasoline" range. However, available crackingv processes, which are eifective in the treatment of ordinary heavy oil fractions, are of limited effectiveness'y 'invproducing' gasoline of commercially acceptable quality from'low grade heavy hydrocarbon oils, suchv as sour crudes, petroleum residues, shale oil, coal tar and the like, which have a high content of sulfur and/or nitrogen and/or metal compounds. 'One prior process involves so-called delayed coking and serves to convert heavy'hydrocarbon' residues intofeed stocks'vi/hich may then be charged into a conventional catalytic cracker. However, thisproce'ssing scheme for heavy residues has several disadvantages. To begin with, the delayedy coker is expensive with respect toboth capital and operating costs, and produces large quantities of by-produ'ct coke In'y many' such cases, a finished' gasoline of commerciallyacceptable sulfur content cannot be obtained.

Similarly, propane deasphalting has been employed for the preliminary treatment of heavy residues to provide a feed for a subsequentcatalytic cracking operation. This processing scheme oiers few advantages over the delayed coking-catalytic cracking scheme described above, and isv inadequate for processing total vor reduced crudes with a high content of sulfur compounds.

As a result of the lack of a processingprocedure which Will economically produce gasoline from such heavy oil stocks, it'has been customary practice to market many heavy sour crudes or petroleum residues of thisv character as Bunker C fuel oil or as asphalt'where possible. The Bunker C fuel oil market is, however, limited by reason of the diiculty of selling a product of high sulfur content and the factv that asphalt market is relatively small. Thus, many Wells which would produce heavy sour crudes are shut-in.

It is an object of the presentinvention to provide an improved process for producing gasoline of commercially acceptable characteristics from low grade, heavy hydro'- carbon oils.

lt is a further object to provide a process-for attaining high yields of commercially acceptable gasoline from such heavy oils.

Still another object is to produce gasoline of premium octane rating, low sulfur content, and good storage stability.

Additional objects and advantages of this invention will be apparent in the description which follows.

In accordance with the invention, the hydrocarbon oil to be processed is initially converted at elevated temperature and pressure in the presence of a heatedcontact material or carrier and in a gaseous atmosphere of predetermined hydrogen partial pressure provided by the h igh temperature reaction of carbon with oxygen andl steam', The carrier, containing a carbonaceous deposit formed by the hydrocarbons undergoing conversion, is regenerated with oxygen and steam to provide the hydrogen-rich atmosphere in which the hydrocarbons are converted. A gasoline fractionis separated from the products of this initial conversion, and this Vfraction (hereinafter referred to as raw gasoline) is then passed, in the presence of part or all of the gasiform products evolved in' thereaction of carbon with oxygen and steam and containing at least 20% by volume of hydrogen, into contact with a hydrogenating catalyst maintained at a predetermined elevated temperature. The gasoline product recovered after the catalytic treatment (hereinafter referred to as finished gasoline) has a high octaney rating and a low sulfur content, and is substantially free of gum-forming constituents.

The term, gasoline fraction, is usedr herein' in` its' conventional meaning, viz., a hydrocarbonA fraction' boiling within the temperature range of 90 to 400 F. It will be apparent that the process of this invention: is applicable to the treatment7 and production of any hydrocarbon fraction, in which material boiling' within the' gasoline range forms the predominant portionV of the fraction.

To simplify and facilitate theffnrther description of the invention, the term, hydrocracking, will be used to describe the step of the process which involves initial' conversion ofthe heavy oil-,and-the`te'rm, hydrotreating, will be employed to describe the catalytic treatment of the raw gasoline from the hydrocracking operation' to'pro duce finished gasoline. t l

The invention provides an eficient integrated process for ythe direct production of high quality gasoline from low grade, heavy hydrocarbon oils. It is a feature of the invention that the presence of hydrogen in the hydrocracking step significantly reduces the formation of coke,

particularly in the case of stocks containing large quantities of resins, asphaltenes or carboids. The presence of hydrogen likewise assists desulfurization, confers superior properties (such as favorable diesel index) to the gas oil distillate, and significantly diminishes the quantity of diolefins in the product efliuent from the hydrocracking operation. It is a further feature that hydrocracking at relatively low hydrogen partial pressures and relatively high temperatures assures a gasoline product of high antiknock value since olefins formed by cracking are not hydrogenated to parans. A relatively low oil partial pressure maintained in .the hydrogen cracking zone also contributes toward the formation of a gasoline product of good anti-knocking rating. The use of a solid, particulate carrier to supply cracking heat to the hydrocracking zone and to transport Icarbonaceous and inorganic residues 'from the hydrocracking zone to the regeneration zone makes hydrocracking insensitive to the presence of sulfur, vanadium, sodium, chlorine and other impurities in heavy oils which yare deleterious to any process that is dependent upon the activity of a catalyst.

The availability of hydrogen from the hydrocracking operation makes it possible to hydrotreat the raw gasoline with important technical and economic Iadvantages which are not obtained in other processes. No hydrogen need be supplied from outside sources, nor is it necessary to carry out the hydrotreating step under conditions which are restricted Eby the necessity of producing hydrogen. In the hydrotreating step, it is not necessary to increase antiknock value as in prior treating yand reforming processes because the raw gasoline produced by hydrocracking has a high octane rating.

'Ihe hydrocracking operation, the hydrotreating operation and the cooperative action of these two phases of the hydrocarbon oil treating process of the invention will now be described in greater detail.

In the initial conversion or hydrocracking step, the heavy hydrocarbon oil contacts a particulate carrier in a cracking zone maintained at a temperature in the range of 850 to 1100 F., preferably in the range of 900 to 1050 F., and containing a gaseous atmosphere comprising hydrogen, carbon monoxide, carbon dioxide and steam, obtained from a regeneration zone. In the hydrocracking step, the total pressure is maintained in the range of 150 to 800 p. s. i. g. (pounds per square inch gage), preferably in the range of 250 to 650 p. s. i. g., and the partial pressure of hydrogen in the gaseous atmosphere in admixture with the hydrocarbon oil is maintained above about p. s. i. (pounds per square inch), preferably in the range of 75 to 150 p. s. i. A hydrogen partial pressure n excess of 200 p. s. i. is not necessary since it has been found that maximum benefits from the presence of hydrogen in the hydrocracking step are obtained at a hydrogen partial pressure within the above specified limits and there is little or no economic justification for employing a hydrogen partial pressure above 200 p. s. i.

The invention is not confined to carrying out the hydrocracking step in any particular form of apparatus. Advantageously, however, the carrier is utilized in iluidized form. The cracking and regeneration zones may be in communicating separate vessels but are advantageously provided in a single vessel. In the latter case, the ow of uidized carrier between the cracking zone and the regeneration zone is restricted by devices like screens` grids, and packed sections containing Raschig rings and the like. Such restricting devices permit the attainment of temperatures of about 1600 to 2500 F., preferably 1700 to 2000 F. in the regeneration zone, while a considerably lower temperature is maintained in the cracking zone. v

The contact material or carrier utilized in the hydrocracking operation may be sand, quartz, alumina, magnesia, Zircon, beryl, bauxite or other like material which will withstand temperatures up to 2500" F. without de.-

-generation or other adverse effect.

which the carbonaceous deposit is removed from the cony tact include:

(A) C-i-l/z O2=CO (B) C+O2=CO2 (C) C+CO2=2 CO The regenerating gas contains a preponderance of steam and a minor proportion of high-purity oxygen, the latter containing 'at least 90% by volume of oxygen, preferably at least by volume of oxygen, and obtained, for example, by air liquefaction and rectification. The specified composition of the regenerating gas insures a high yield of hydrogen and, in this connection, a ste-am-to-oxygen volume ratio in the range of 1.5 :l to 5:1 is generally satisfactory. It is preferable, as a practical matter, to employ a steam-to-oxygen volume ratio of the order of 2:1 to 3:1 and thereby avoid a very high regeneration temperature. As a general rule, it is advisable to conduct the regeneration at a temperature approaching the maximum permissible with the carrier and reactor materials employed, utilizing the smallest steam-to-oxygen volume ratio which will provide the desired temperature control.

The efuent gases from the renegeration zone, wherein the carbonaceous deposit is removed from the surfaces of the carrier particles as described, thus contain not only hydrogen, carbon monoxide and carbon dioxide resulting from the aforementioned reactions, but also water vapor as a result of the excess steam utilized in the regenerating gas. This gasiform effluent passes into the cracking zone and serves as the hydrogen-rich atmosphere for the hydrocarbon conversion reactions. After conversion of the hydrocarbon oil, the total gaseous etlluent 'from the hydrocracking step contains the hydrocarbon conversion products and the portion of the gaseous atmosphere from the regeneration zone which was not consumed in the hydrocarbon conversion reactions.

The heavier hydrocarbons in the product eftluent of the hydrocracking operation are separated from the lighter products, including raw gasoline and normally gaseous products, and the raw gasoline is then hydrotreated by contact with a catalyst in the presence of part or all of the normally gaseous products from the hydrocracking operation, which contain at least 20% by volume of hydrogen.

In hydrotreatment, the raw gasoline is subjected to a combination of processing conditions, in particular, the type of catalyst, the reaction temperature and the hydrogen partial pressure, which together eiect mild hydrogenation of the raw gasoline in the sense that impurities therein such as diolefins are hydrogenated to olens, and organic compounds yof sulfur, nitrogen and oxygen are destructively hydrogenated, while the valuable olefns in the raw gasoline are not substantially hydrogenated to parains.

Suitable hydrotreating catalysts include the oxides of aluminum and silicon having a high surface area, say of the order of square meters per gram and higher as measured by low-temperature nitrogen adsorption. Bauxite, activated alumina and other catalysts derived from alumina gels are typical oxides of aluminum used in hydrotreating raw gasoline, while natural and synthetic clays or silicates, and other catalysts derived from silica gels, especially those containing minor amounts of dicultly reducible metal oxides such as zirconia, titania and alumina, are typical oxides of silicon suitable for hydrotreating raw gasoline. It is often advantageous to add promoters to the oxides of aluminum or silicon. Desirably, the promoter comprises. an element selected from the classv consisting of the metallic elements of groups VA, VIA and VIII of the periodic table'. Examples of particularly suitable catalytic promoters'comprise mol-'ybdenum, chromium, tungsten, cobalt,.vanadium,y platinum and nickel. Two or more caatyltic promoters may be used at the same time; the use of cobaltandmolybdenum together, for example, gives excellent results. The` promoters are conveniently incorporated in the' aluminav or silica as oxides or suliides by known methods of preparation involving impregnation, precipitationor co-precipitation. These oxides or suliidesV are partially or completely reduced by hydrogen to their most active formi. The effective promoter may thus comprise a metallicelement of the above-specified groups in the form of an oxide, a sulfide or as the elemental metal.

The hydrotreatingoperation is generally carried out at temperatures in the range of 750 to 1025 F. and with hydrogen partial pressures in the range of 20 to- 400 p. s'. i. (pounds per square inch). The temperatures andv hydrogen partial pressures vmaintained in the hydrotreati'ng zone will, for best results, be selected in relation tothe particular catalyst employed and the impurities of the raw gasoline which are to be eliminated. Thus, where hydrotreating is used essentially for removing gum-forming constituents like diolens, an oxide of silicon such as clay may be used preferably at a temperature of 775 to 850 F. and with a hydrogen partial pressure ofv 100 to 250 p. s. i. If hydrotreatment is required toremove sulfur compounds from the raw gasoline, an oxide of silicon may be employed as catalyst, preferably at a temperature of 875 to 950 F. and with a hydrogen partial pressure of 125 to 350 p. s. i., but when thev siliceous catalyst has a promoter as hereinbefore mentioned, preferably, the temperature is 800 to 900 F. and the hydrogen partial pressure is 30 to 70 p. s. i. In each-of the three foregoing cases, an oxide of aluminum such as activated alumina may be used in place of the siliceous catalyst, the cited ranges of hydrogen partial pressure being essentially the same but the temperature ranges being preferably raised by about 50 F. Thus, to desulfurize rawgasoline with activated alumina having a promoter a-temperature of 850 to 950 F. is preferred. Hydrotreating conditions selected to effect desulfurization will simultaneously eliminate diolens.

The hydrotreating step is suitably carried out in conventional-gasoline treating apparatus wherein, in accordance with the invention, the gasoline hydrocarbons and at least a portion of the hydrogen-rich gaseous effluent from the hydrocracking step are brought into contact with the particulate catalyst. Preferably, hydrotreating iscarried out in a' uidized catalyst bed. The catalyst is continuously or intermittently withdrawn-from-the hydrotreating zone and regenerated in any convenient manner, as by treating it at elevated temperature with oxygen or air and, if desired, other gasessuch as steam.

The particular apparatusv used for the hydrot-reating step and the particular method of regenerating the catalyst form no part of the present invention andany convenient apparatus and method of catalyst regeneration may be employed. In regenerating lthe catalyst care'must be taken, however, in accordance with commercial regeneration techniques, to avoid the use of temperatures, say above l200 F., which destroy or adversely affect the catalyst.

Advantageously, the desired elimination of'rgasolineim purities byhydrotreatment is insuredv by employing a raw gasoline feed rate in the range of 0.5 to 5, preferably 0.5 to 1.5, volumes of liquid per hour per volume `of-catalyst, while employing a hydrogen flow rate of 500'to 2500 standard cubic feet (calculated as pure hydrogen) per barrelof raw gasoline fed.

The effluent from the treating-zone will contain vapors of the hydrocarbons within the gasoline range adinix'e-l with a small amount' of higher boilinghydrocarbons` 6 formed. by polymerization andi/'0r condensation the hydroteati'ngzone, and with more volatile compounds including' readily removable' sulfur' compounds forined by the breakdownl of thiophenes and like refractory sulfur compounds. The effluent is fractionated to separate the desired gasoline fraction from other constituents.

The finished gasoline thus produced is of low sulfur content, high stability and high octane number, meeting the specifications for commercial motor gasoline notwithstanding the' presence of av substantial quantity of sulfur compounds and gum-forming constituents originally in the cracked raw gasoline. The sulfur content ofv the finished? gasoline can be reduced to below 0.1% by' weightv by thev present process, as well as below the 0.3% by weight level presently accepted for marketable gasoline. The clear research octane number of the iinished gasoline is at least 80 and generally approaches 90.

The higher boiling liquid constituents of the hydrotreating"l zone effluenti form a high quality recycle stock which is advantageously returned' to the hydrocracking zone forv a' conversion to gasoline hydrocarbons. It is thus apparent that` there is closefcoope'ration between the hydrocracking and-hydrotreaing steps in attaining maximuni conversion of the oil originally charged to gasoline hydrocarbons'.

It is within the contemplation of the invention to employ all ofthe efllue'nt from the hydrocracking step boiling below th'ehydrocarbons in the gasoline range as the gaseous atmosphere for the hydrotreatment of gasoline hydrocarbons. Thus, the total efuent from the hydrocrackingstep maybe merely cooled to condense out hydrocarbons boiling above 400 F., i. e., gas oil, with the remanderi'of the" gasiforrn efuent being expandedv or compressedto the required total pressure to give the desired hydrogen partial pressure in the hydrotreating step. Preferably, however', further treatment and separation of the total? effluent is effected. For example, water may be removed by fi'rstco'oling the hydrocracking effluent by any convenient-means to condense out hydrocarbons boiling above 400 F. and then cooling the remaining portion of the eiuent to the desired degree to`effect condensation of water and a portion of the' gasoline fraction. The heavier aqueous phaseof the condensate is thus eliminated and the condensed gasoline together with the uncondense'd portion! of'the/efuent, after preheating, say to 500' to 800 F., is then. subjected to the hydrotreating step,

In addition tothe removal' of water from the hydrocracking eluent, it'is frequently advisable to remove light ol'etinicv hydrocarbons like propylene which tend to be hydrogenated to`less valuable products in the hydrotreater and? to" eliminate at least some of the carbon dioxide. For' instance, the portion ofthe hydrocracking eluent boiling below the gasoline range may be treated' to remove'.A carbondioxide and' C3 and C4 hydrocarbons by conventional low-temperature' absorption, e. g., with dieth'anolamine. Y

The portion of the' hydrocracking etuent boiling below the gasoline range generally contains about 20 to 30% by volume of hydrogen admixed principally with carbon monoxide', carbon dioxide, and light hydrocarbons Wlierea' fairly'high hydrogen partial pressure is desired in thehydrotreating step, it is of advantage to raise the hydrogen c'ontent'above the 20 to 30% level rather than toraise'the total pressure ofthe hydrotreating zone' above about 400 p. s. i. g. which would otherwise benecessaryto provide the desired hydrogen partial pressure. In such? cases, the gas portion may be treated to convert carbon monoxide therein to carbon dioxide Whicli'is then removed b`y means of a carbon dioxide absorbent. this'manner, the hydrogen content of thel gas" stream utilizedfor the' hydrotreating step may be increasedz to about 50 to 75%; b'y volume. In accordance with one attractiveA processing' scheme, the portion of the'v hydrocracking: effl'lenftl boiling below the gasoline range'pis treated to: remove C3-ai1`d"C.V hydrocarbons and carbondioxide, and then fed, together with steam, to a converter wherein the gases contact a water-gas shift catalyst, e. g., alkalized iron, and part or all of the carbon monoxide reacts with the steam to produce carbon dioxide and hydrogen. After condensation and removal of excess steam, and removal of carbon dioxide, the concentration of hydrogen in the remaining gas is easily double what it originally was.

It will be apparent that various gas treating expedients may be applied to the gases from the hydrocracking step to produce a gaseous atmosphere for the hydrotreating step in which hydrogen is present in a wide range of concentrations. Accordingly, the process of the invention has a high degree of exibility ensuring the efcient and economical conversion of low grade, heavy oils to a maximum quantity of high quality gasoline.

For a fuller understanding of the invention, reference is now made to the accompanying drawings wherein are shown diagrammatically two processing schemes embodying the present invention.

Referring to Figure 1, the numeral designates a hydrocracking reactor having an oil feed inlet 12 near the bottom of cracking zone 11 in the upper portion of reactor 10. The lower regeneration zone 13 of reactor 10 is provided with an inlet 14 through which oxygen and steam are supplied for regeneration of a particulate carrier which is in a iluidized state and circulates from zone 11, down through the annular space 15 between the walls of reactor 10 and tube 18, into zone 13, and thence into and up through tube 18 and back to zone 11. The annular space 15 is filled with Raschig rings or like packing to improve stripping of hydrocarbons from carrier particles as they move down through the packing against the up-ow of regeneration product gases from zone 13. Steam or other inert gas is introduced at 16 into uptransport tube 1S which has an adjustable opening 20 at its lower end; regenerated carrier in uidized condition flows into tube 18 and is transported back to cracking zone 11. The total hydrocracking effluent is removed from the top of reactor 10 through conduit 24 which communicates with cooler 26 and separator 28 wherein the water separates out and is eliminated. From separator 28, the liquid hydrocarbon products are passed into primary fractionator 30 where heavy gas oil is separated and removed. Light gas oil separated in primary fractionator 30 may either be removed from the system or may be recycled to hydrocracking reactor 10 through line 32. From primary fractionator 30, the gasoline fraction (C4 hydrocarbons to 400 F. end point) is combined with the portion of the hydrocracking effluent boiling below the gasoline fraction, which portion passed from separator 28 into absorber 34 wherein a propane-propylene fraction is removed from this portion. The combined fractions are then passed through heater 36 and fed through line 38 into hydrotreating reactor 40 provided with an inlet 42 for oxygen and steam for catalyst regeneration. The eluent from hydrotreating reactor 40 passes through cooler 44 into separator 46 from which condensed water is removed. The non-condensible gaseous product is removed from the top of separator 46 through line 48. The liquid hydrocarbons from separator 46 are passed into secondary fractionator 50 in which the finished gasoline is separated from higher boiling hydrocarbons (gas oil) that are desirably returned as recycle to the hydrocracker 10 through line 32. f

When, as pointed out hereinbefore, it is 'desired to increase the hydrogen content of the portion of the hydrocracking effluent boiling below the gasoline range, this portion is subjected to one or more treatments before it is passed, together with the gasoline fraction, into the hydrotreating reactor. A processing system suitable for this type of operation is shown in Figure 2.

The overall owsheet for, Figure 2 is the same as tha shown in Figure 1 except that the equipment shown in Figure 2 is inserted between lines 35 and 37 of Figure 1.

The scrubbed gas from which a propylene-propane fraction has been removed in absorber 34 ows through line 3S into DEA (diethanolamine) scrubber 56 whichabsorbs carbon dioxide from the gas. The thus treated gas thence passes through heater 58 and together with added steam enters shift converter 60 containing a bed of alkalized iron shift catalyst. From shift converter 60, the gas passes .through condenser 62, wherein water condensate is removed, and into a second DEA absorber 64 wherein carbon dioxide formed by the shift reaction is removed from the gas. The unabsorbed gaseous efuent from DEA absorber 64, which now contains a high concentration of hydrogen, is passed through line 66 and combined in line 37 with the raw gasoline flowing through line 31.

Example 1 The following example describes an operation employing Boscan (Venezuela) crude as feed stock in the system of Figure 1. This crude is extremely heavy (10.5 API gravity), is very high in sulfur content (5.0% by weight), and has a high content of asphaltenic materials (13% by weight Rams'oottom carbon residue) and inorganic constituents (ca. 0.3% by weight). Because of these properties, the crude has not previously been considered for conversion to gasoline on a commercial scale. Furthermore, because of the large quantity of inorganic constitutents, there is no market for the crude as Bunker C fuel even if the necessary viscosity modification were made. The crude, preheated to 750 F., is fed into hydrocracking reactor 10 containing a iluidized mass of bauxite of a particle size averaging 120 mesh. The temperature of cracking zone 11 is 980 F. while in regeneration zone 13 it is 1750 F. The total pressure is 400 p. s. i. g. With feeds of 10,000 B./D. (barrels per day) of crude, 8.0 MMSCFD (million standard cubic feet per day) of 95% oxygen and 15.2 MMSCFD of steam, the hydrogen and oil partial pressures in cracking zone 11 are 65 and p. s. i., respectively. Y

The effluent from hydrocracking reactor 10 is cooled and 8170 B./D. of condensable hydrocarbons are separated from the water condensate in separator 28. The condensible hydrocarbons are fractionated in tower to yield 4100 B./D. of raw gasoline (400 F. end point), 2900 B./D. of light gas oil boiling to 700 F., and 1170 B./D. of heavy gas oil boiling above 700 F.

The uncondensible gas from separator 28 totals 31.4

MMSCFD, and is componentially as follows (in MMSCFD);

3 4 H2 9 9 o 5 Go 7 s 1 1 CO2 5 9 0 5 Hts 1 0 0 7 N 2 0 6 After removing in absorber 34 a large portion of the propane and propylene and, incidentally therewith, some CO2, H28, C2H4 and CZHS, this eluent gas totals 28.2 MMSCFD and contains over by volume of hydrogen.

The raw gasoline has a clear research octane number of 88 and an olefin content of 45% by volume but contains about 1.5% by weight of sulfur and does not meet storage stability specifications except with unusually large additions of gum inhibitors. After reheating to 800 F. in heater 36, the raw gasoline together with the abovementioned Yeluent gas from absorber 34 is fed to hydrotreater containing a fluidized mass of particulate catalyst prepared by impregnation of 10% by weight of M003 in 90% by weight of A1203. The hydrotreating temperature is maintained at 890 F., the raw gasoline space velocity at 2.5 volumes of liquid per hour per volume of catalyst in the hydrotreating zone, and the total pressure at 300 p. s. i. g., which with the proportions of raw gasoline and hydrogen-containing gas given above,

provides a hydrogen partial'v pressure. of- 93; p. s. i. in the hydrotreating zone.

The eiuent from hydrotreater 40 is cooled-v in cooler` 44 and water condensate isremoved; in separator- 46. 'Ihe hydrocarbon layer from separator 46 is fractionated in tower 50 to yield 3690 B./D. of nished gasoline of 400:o F. end point and 160 B./D. of hydrocarbons boilingabove 400 F. By recycling all of the hydrocarbons boiling above 400 F. from fractionator 50.to hydrocracker through line 32, the yield of finished gasoline. is increased to approximately 3800 B./D. The product gas from line 48 .consists of 27.4 MMSCFD of a mixture. containing approximately 30% by volume of each of hydro,- gen and carbon monoxide. This product gas mayv be used for fuel but is preferably utilized. in chemical syn. theses requiring hydrogen and/or carbon. monoxide as reactants.

A further increase in gasoline yield is` obtained by recycling the light gas oil from tower- 3.0. to hydrocracker 10 through line 32. By recycling all. of this light gas oil, the total yield of finished gasoline recovered at tower 50 rises to substantially 5500 B./D. or an overall yield of 55% by volume of the charged crude.

The nished gasoline recovered from the. process contains only 0.25% by weight o f sulfur andy meets ASTM existent gum and storage stability requirements. It has a clear research octane number of 87 and contains the bulk of the olens originally present in the rawgasoline obtained from the hydrocracking step. It will be seen that the hydrotreating step has substantially improved. sulfur content and stability without significantly impairing clear research octane number. If the hydrotreater were operated without hydrogen, the resultant gasoline product would contain about 1.2% by weight of sulfur, `a level .completely unsatisfactory for the commercial motor fuel market. Thus, the integrated process of the invention produces a high yield of high-quality finished gasoline meeting all market requirements, from a low-grade heavy crude having a high content of sulfur, nitrogen and metal compounds.

Example 2 In this example, the Boscan crude of Example l is processed in the system shown in Figure 2. vThe hydrocracking step is exactly as described in Example 1. Similarly, the hydrocracking efluent undergoes separation in separator 28, fractionator 30 and absorber 34 as before. However, of the scrubbed gas leaving absorber 34, only 3.7 MMSCFD is passed through line 35 into DEA absorber 56, the remainder being withdrawn from the system. The gaseous effluent from DEA absorber 56 is reacted with 18.4 MMSCFD of steam over an alkalized iron Water-gas shift catalyst at 800 F. in shift converter 60. After removing water condensate and subsequent rescrubbing in DEA absorber 64, 2.9 MMSCFD of gas containing 72% by volume of hydrogen is obtained. This hydrogen-rich gas passes through line 66 and, together with 4100 B./D. of raw gasoline, is fed through line 37 to hydrotreater 40. The catalyst in hydrotreater 40v is the same as in Example 1. However, the hydrotreating temperature is maintained at 875 F. and the raw gasoline space velocity at l volume of liquid per hour per volume of catalyst in the hydrotreating zone. The total pressure in hydrotreater 40 is 110 p. s. i. g. which, with the given ilow rates of raw gasoline and hydrogen-rich gas, provides a hydrogen partial pressure of 40 p. s. i.

Yields of nished gasoline and liquid hydrocarbons boiling above 400 F. are substantially those given in Example 1. However, the gaseous eluent from separator 48 amounts to 3.3 MMSCFD of a mixture consisting essentially of approximately equal volumes -of hydrogen and light hydrocarbons. The quality of the finished gasoline is substantially identical with that of Example 1. Thus, whether the hydrogen-containing gas providing the atmosphere for the hydrotreating step conrains 35%- or 7.2% by; uolume. or hydrogen, the yield and quality. or the-finished gasoline are essentially unchanged.

application is a continuation-impart of copending 'application Serial No. 139,758-, tiled January 20, 1950, now Patent No. 2,606,862, which is directed to the hydro-V cracking of hydrocarbons.

In View otthe! various modilications of the invention which wille Occur to those skilled4 in the art upon con,-l sideration ofthe foregoing disclosure without departing from the spirit or scope thereof, only such limitations should be imposed. as are indicated by the appended claims.

What is, claimed is:

1 The process of producing finished, gasoline ofV high quality froma heavy hydrocarbon oil which comprises treating said; oilat.` arr elevated temperature in a reaction zone,` in the presence of a heated particulate contact material and in an atmosphere of steam and regeneration pigoduct gases, including hydrogent resulting from the regeneration with steam and oxygeri, in a regeneration zone maintained at a temperature of at least 1600 F., ofthe c arbonaceous deposit-formed on said contact material during. conversion of saidoil in said reaction zone, removing hydrocarbon vapors andv regeneration product gases aseiiluent from said reaction zone, separating from saidv eluent a hydrocarbon fraction boiling above the gasolinerange, transferring substantially all of the normally liquid por-tionl of said eluent comprising substantially. only hydrocarbons boiling in the gasoline range to* .gether with at least a substantial. portion ofthe normally gaseous portion. of saidf effluent, including the hydrogen therein, to. a second reaction Zone, reacting the transf erred portions in said second reaction zone at an elevated temperature. andv pressure and. in the. presence of a.

particulate catalyst to effect mild. hydrogenation, and recoveringtroni the effluent from said second reaction zone finished gasoline. of high quality.

2. The process of claim 1 wherein the hydrogen exerts in the first-mentioned reaction zone a partial pressure in the range of 35 to 200 p. s. i. and in the second reaction zone a partial pressure in the range of 20 to 400 p. s. i.

3. The process of claim 2 wherein the temperature in the first-mentioned reaction zone is in the range of 850 to 1100 F. and in the second reaction zone is in the range of 750 to 1025 F.

4. The process of claim 3 wherein the particulate catalyst is selected from the class of catalysts consisting predominantly of the oxides of aluminum and silicon having high surface area.

5. The process of producing finished gasoline of high quality from a heavy hydrocarbon oil which comprises treating said oil at a temperature above 850 F. in a reaction zone in the presence of a heated particulate contact material and in an atmosphere of steam and regeneration product gases, including carbon dioxide and at least 20% by volume of hydrogen resulting from the regeneration with steam and oxygen, in a regeneration zone maintained at a temperature above about 1600 F., of the carbonaceous deposit formed on said contact material during conversion of said oil in said reaction zone, removing hydrocarbon vapors and regeneration product gases as ellluent from said reaction zone, separating from said eiuent `substantially only hydrocarbons boiling in the gasoline range and a gaseous fraction, removing C3 hydrocarbons and carbon dioxide from said gaseous fraction, passing the thus separated hydrocarbons boiling in the gasoline range together with at least a substantial portion of the residual gaseous fraction, including the hydrogen therein, to a second reaction zone, effecting mild hydrogenation in said second zone at an elevated temperature and pressure and in the presence of a particulate catalyst, and recovering from the eluent from said second reaction zone finished gasoline of high quality.

6. The process of claim 5 wherein the hydrogen exerts in the first-mentioned reaction zone a partial pressure in 11 the range of 75 to 150 p. s. i. and in the second reaction zone a partial pressure in the range of 20 to 400 p. s. i.

7. The process of claim 6 wherein the temperature in the first-mentioned reaction zone is in the range of 900 to 1050 F. and in the second reaction zone is in the range of 750 to 1025 F.

8. The process of claim 7 wherein the particulate catalyst is predominantly an oxide of aluminum having high surface area, the temperature in the second reaction zone is in the range of 825 to l000 F., andthe hydrogen partial pressure in the second reaction zone is in the range of 30 to 350 p. s. i.

9. The process of claim 7 wherein the particulate catalyst is predominantly an oxide of silicon having high surface area, the temperature in the second reaction zone is in the range of 775 to 950 F., and the hydrogen partial pressure in the second reaction zone is in the range of 30 to 350 p. s. i.

10. The process of producing finished gasoline of high quality from a low-grade, heavy hydrocarbon oil which comprises hydrocracking said oil at an elevated pressure and a temperature above about 850 F. in the presence of heated carrier particles and regeneration product gases, including at least 20% by volume of hydrogen resulting from the regeneration of said carrier particles by reacting the carbonaceous deposit formed thereon by said oil with steam and oxygen at a temperature above about 1600o F., fractionating the mixed hydrocracking eflluent of hydrocarbon vapors and regeneration product gases to separate therefrom a normally gaseous stream containing hydrogen and a stream of substantially only hydrocarbons boiling in the gasoline range, increasing the hydrogen concentration of at least a portion of said normally gaseous stream by absorbing C3 hydrocarbons therefrom,

efecting mild hydrogenation of said stream of hydrocarbons in the presence of the normally gaseous stream of increased hydrogen concentration and a particulate 12 catalyst at an elevated pressure and a temperature in the range of 750 to 1025 F., and separating from the hydrogenation effluent an oil boiling above 400 F. and nished gasoline of high quality.

1l. The process of claim 10 wherein the oil separated from the hydrogenation eluent is returned to the hydrocracking step.

12. The process of claim 10 wherein the hydrogen concentration of at least a portion of said normally gaseous stream is further increased by subjecting carbon monoxide therein to the water-gas shift reaction.

13. The process of claim 12 wherein the hydrogen concentration `of at least a portion `of said normally gaseous stream is further increased by absorbing carbon dioxide therefrom.

14. The process of claim 10 wherein the particulate catalyst is predominantly an activated alumina, the normally gaseous stream of increased hydrogen concentration contains at least 50% by volume of hydrogen, and the hydrogenation temperature is in the range of 825 to l000 F.

15. The process of claim 10 wherein the low grade, heavy hydrocarbon oil has a sulfur content of the order of 5% by Weight and the hydrocracking pressure is in the range of 250 to 650 p. s. i. g.

References Cited in the le of this patent UNITED STATES PATENTS 2,227,671 Pier et al. Jan. 7, 1941 2,284,603 Belchetz et al May 26, 1942 2,334,159 Friedman Nov. 9, 1943 2,392,749 Lewis et al. Jan. 8, 1946 2,450,753 Guyer Oct. 5, 1948 2,464,539 Voorhies et al Mar. 15, 1949 2,541,229 Fleming Feb. 13, 1951 2,541,317 Wilson Feb. 13, 1951

Claims (1)

1. THE PROCESS OF PRODUCING FINISHED GASOLINE OF HIGH QUALITY FROM A HEAVY HYDROCARBON OIL WHICH COMPRISES TREATING SAID OIL AT AN ELEVATED TEMPERATURE IN A REACTION ZONE IN THE PRESENCE OF A HEATED PARTICULATE CONTACT MATERIAL AND IN AN ATMOSPHERE OF STEAM AND REGENERATION PRODUCT GASES, INCLUDING HYDROGEN RESULTING FROM THE REGENERATION WITH STEAM AND OXYGEN, IN A REGENERATION ZONE MAINTAINED AT A TEMPERATURE OF AT LEAST 1600*F., OF THE CARBONACEOUS DEPOSIT FORMED ON SAID CONTACT MATERIAL DURING CONVERSION OF SAID OIL IN SAID REACTION ZONE, REMOVING HYDROCARBON VAPORS AND REGENERATION PRODUCT GASES AS EFFLUENT A HYDROCARBON FRACTION BOILING ABOVE THE SAID EFFLUENT A HYDROCARBON FRACTION BOILING ABOVE THE GASOLINE RANGE, TRANSFERRING SUBSTANTIALLY ALL OF THE NORMALLY LIQUID PORTION OF SAID EFFLUENT COMPRISING SUBSTANTIALLY ONLY HYDROCARBONS BOILING IN THE GASOLINE RANGE TO-

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