US2528586A - Catalytic desulfurization and cracking of sulfur-containing petroleum - Google Patents

Description

Nov. 7, 1950 J. E. FORD, JR 2,528,586

CATALYTIC DESULFURIZATION AND CRACKING 0F SULFUR-CONTAINING PETROLEUM Filed June 3, 1947 ASPHALT fdl INVENTOR.

? da@ E img C@ BY JM WMA Patented Nov. 7, 1950 y 2528586 cArALYTIc DEsULFURlzA'rIoN AND CRACKING OF SULFUR-CONTAIN- ING PETROLEUM Jo'hE. Ford, -Jr., Garden city, N. Y., assigner to HoudrProcess Corporation, Wilmington, Del., a corporation of DelawareV "I Application June 3, 1947, Serial No. 752,211

This invention' relates to the conversion of hydrocarbon `material to useful products and is especially directed to the production ofhydrocarbon products,.such 4a, engine fuels, fuel oil,

kerosene and the like.4 This invention involves the processing of crude hydrocarbon oils hav 7 claims." (c1. 19e- 50) Y 2 of the light fraction, and in the other of which conversion zones a major amount of the total freshly regenerated active cracking catalyst coning high sulfur contents, such as sour crude oils,

to yield products of sulfur contents Many crude petroleum: oils have sufficiently Vcoxnnnercially acceptable high sulfur content that the various products,

such as gasoline or diesel fuel, 'produced by distillation of the crude oil have sulfur contents that are commercially unacceptable or undesirable and generally must be'treated separately, as by expensive chemical methods, to reduce the sulfur content. Chemical methods frequently are useful only to effect a reduction in sulfur content and may cause a substantial reduction in yield of the finished product. Existing catalytic or extraction methods for the reduction of sulfur content involve the considerable expense incident to a separate process; In the case of diesel fuel, prior processes have been either expensive to operate or have resulted in depreciation of this material as a fuel for diesel engines. Indeed, the problem of sulf-ur content is not confined to fractions having high sulfur contents since' many straight run gasolines have a low content of sulfur, such as 0.03 to 0.10 per cent (by weight), which, although low, is sufficient to influence the lead susceptibility and therefore results in an uneconomical use of tetraethyllead.

Moreover, some sulfur-containing crudes have Va corrosive effectgon thewreflnery equipment due to the sulfur compounds either originally present or formed during the rening.` Such crudes generally but not always fall in the category Yof' crudes having a sulfur content of greater than 1.0 percent by weight of`sulfur in the 400 to l000 F. fraction and will be referred to herein as high sulfur or sourcrudes. It should be -understood, however, that the types and effect of the sulfur compounds present vary lfrom crude to crude and that, although the above classification is convenient, the present' invention in-Vv cludes the processing of crudes which have lower sulfur contents butV which behave as souricrudes.

It has now been found, in accordance with'the invention, that improvements and economies in 1 the operation of cracking systems employing movingr catalysts result by employing freshlyregenerated uent active cracking catalyst of the type described below-in two conversion zones, in one of which conversion zones a minor amount, of the totalfreslcly regenerated catalyst contacts a normally liquid light straight run fraction ofa cru-'ie petroleum oil, which light fraction has an obiectionable amount o f sulfur, under mild f tacts a heavy hydrocarbon fraction, such as a gas oil or heavier, under cracking conditions and effects conversion of the heavy fraction to substantial amounts of motor gasoline. The cracking catalyst in each conversion zone passes therethrough in a fluent state and accumulates a coke deposit as a result of the contact with the hydrocarbon material in each zone. Coked catalyst is removed severally from the two conversion zones and regenerated in a single common regeneration zone by oxidizing at least a portion lof the coke deposit on the catalyst. Catalyst in a freshly regenerated state is then removed Vfrom the regeneration zone and conveyed to the two zones in the proper amounts.

The unitary integrated process described herein furnishes a method whereby a refinery can produce superior motor fuels andother petroleum products from virtually all of the various fractions of. a high sulfur crude oil at a low cost. The normallyvliquid light straight r-un fraction which is processed in one conversion zone (hereafter called the desulfurization zone for convenience, the other conversion zone being called the cracking Zone) to yield products having commercially acceptable sulfur contents may consist of any or all of the straight run or virgin fractions boiling below about 750" F., such as gasoline, kerosene, diesel fuel or light fuel oil, and

ume'percentages unless otherwise designated).

Such gasoline has the high octane characteristic of gasoline produced by catalytic cracking under-conventional cracking conditions (which are :much more severe than the conditions in the -desulfurization zone), and is generally above 75 octane number (clear) by the CFR-motor method. The diesel oil fraction may be desulfurized alone or in admixture with straight run gasoline end boiling Vpoint about 400 to 450 F.)

. obtained from the high sulfur crude oil.

Desulfurization of .the straight run gasoline from high sulfur crudes (which gasoline generconversion conditions and effects desulfurization per cent (by weight) of sulfur and is therefore not marketable or has a poor lead susceptibility or both because of high sulfur content) under the described conditions removes about 60 to 90 per cent of the sulfur originally present to yield a gasoline of high lead susceptibilty. Moreover, desulfurization of straight run gasoline of low sulfur content such as 0.02 to 0.09 per cent (by weight) of sulfur, may be eilected by the processes herein described, whereby the lead Susceptibility and frequently octane number of such gasolinas is improved. Such a low sulfur gasoline may be effectively desulfurized either alone or together with diesel fuel cuts from a high sulfur crude oil. When the straight run gasoline from a high sulfur crude oil is desulfurized together with the diesel fuel cut from the same crude, the sulfur content of the final gasoline is slightly higher although the lead susceptibility is not depreciated. In contrast to known methods of operation, the described method of operation of the desulfurization zone considerably increases the amount of' gasoline suitable for use in high octane motor fuels with a considerable increase in the octane-barrels of gasoline.

Since a minor amount, preferably less than 25 per cent, of the total catalyst circulating in the system passes through the desulfurization reactor, this reactor is small in comparison to the cracking reactor and the advantages of desulfurizing the light fraction can be gained with only a small increase in the cost of the total equipment and may, in the case of refinery installations presently having cracking and regenerating equipment, be installed at a cost which is very low in comparison to the advantages gained. Thus, in accordance with one embodiment of the invention involving fluent catalysts employed as moving beds in the reactors and in the regenerator, the desulfurization reactor is a part of a unitary plant, which also comprises a relatively large reactor for cracking heavy hydrocarbon stock under conventional cracking conditions for the maximum production of gasoline and a regenerator or kiln for the removal of the coke deposited on the catalyst due to contact with the hydrocarbon material. The catalyst employed is preferably a cracking catalyst'of moderate activity as described below,

such as a silica-alumina contact mass. After regeneration, the major portion of catalyst is passed through the cracking reactor while a minor portion, preferably less than 25 per cent of the total catalyst leaving the regenerator, is passed to the desulfurization reactor where it contacts a light distillate fraction under mild conversion conditions, and eil'ects desulfurization of the light fraction. By maintaining a low catalyst to oil ratio in the desulfurization reactor (where catalyst to oil ratio is the ratio of the weight of catalyst introduced to the reaction zone per unit time to "itlrweight of oil introduced to the reaction zone per unit time; i. e., pounds of catalyst per pound of oil) a relatively large amount of light distillate is `desulfurized without diverting much catalyst from the cracking reactor and thereby avoiding a reduction in the charging rate of oil to the latter.

Passage of the fluent catalyst through the desulfurization reactor as a moving non-turbulent bed has advantages particularly when the light fraction is passed countercurrently therethrough. Under these conditions, the light fraction is charged to the less active portion of the catalyst and the less refractory sulfur compounds are decomposed. As the light fraction progresses up the catalyst bed, additional sulfur compounds are 'decomposed until only the more refractory sulfur compounds remain. Such compounds encounter, near and at the top of the bed,'the catalyst in a more active state. Also, if the catalyst is introduced at a temperature higher than the average reactor temperature, the catalyst is at a higher temperature. Hence, the refractory sulfur compounds are decomposed near the top of the bed with a minimum of conversion of the remainder of the fraction. Moreover, such counterflow is more efficient in removing` heat when the catalyst is charged to desulfurization reactor fxilom the regenerator without intermediate cool- It has been found, in accordance with the invention, that a particularly eective mode of operation is to maintain a relatively low catalyst to oil ratio, preferably less than 0.5, but greater than 0.05, such as a ratio in the range of 0.1 to 0.4, in the desulfurization reactor, while maintaining a relatively high ratio, preferably 1.5 or greater, but generally less than 20, such as a ratio in the range between 1.8 and 5.0 in the cracking reactor. When relatively low catalyst to oil ratios, such as 0.1 to 0.4, are maintained in the desulfurization reactor, a large quantity of light fraction can be desulfurized without affecting the throughput of the cracking reactor. Thus, for example, equal amounts of light and heavy fractions can be charged to the desulfurization and cracking reactors while maintaining catalyst to oil ratios of 0.4 and 1.5, respectively, in these reactors, by diverting less than 25 per cent of the total catalyst to the desulfurization reactor. In some cases, the desulfurization reactor may be maintained at a lower temperature than the cracking reactor; the space rate in the desulfurization reactor is generally higher than that in the cracking reactor although approximately the same ranges are useful in both reactors. In the case of existing installations for cracking to whichdesulfurization reactors are added, essentially the same throughput in barrels per day can be maintained after the addition of the desulfurization reactor as had been maintained before the change by vchanges in the operating conditions which are within the inherent ilexibility of the system.

In order to understand the invention more fully, reference should be had to the drawing which illustrates various embodiments of the present invention, which invention is not, however, limited in scope thereto. These embodiments will be described in connection with operations in which a uent refractory catalytic contact mass in molded or aggregated form. such as pellets or spheres, is circulated by gravity as a moving, non-turbulent bed through either or both reaction and regeneration vessels. Details of such systems, as applied to cracking operations, have been described in various published articles (see, for example, 'I'he T. C. C. Cracking Process For Motor Gasoline' Production by R. H. Newton,.G. S. Dunham and T. P. Simpson, Transactions Of The American Institute Of Chemical Engineers," volume 41, page 215, April 25, 1945, and the articles there cited) and hence will not be repeated here.

The drawing, in which conventional auxiliary equipment have been omitted for clarity, shows a schematic cracking system illustrating the refining of a crude oil wherein a light fraction is desulfurized and a heavy fraction is cracked.

In the drawing, a catalyst of the type used in cracking operations and discussed more fullybelow, such as a catalytically active clay, or preferably a low alkali content silica-alumina gel, which has been charged to the system preferably in the form of granules, pellets, or beads of about 3 to 8 mesh and which has been freshly regenerated, is fed by line 2 to hoppers 3 and 4 and thence by lines 5 .and 6 to a cracking reactor 1 and a desulfurization reactor 8. A normally liquid light straight run fraction prepared and preheated as described below and having a boiling range below 750 F., is fed by line 9 to desulfurization reactor 8. fraction passes upwardly through a downwardly moving bed of catalyst in reactor 8 under the conditions described below and is thereby desulfurized and otherwise subjected to the action of the cracking catalyst. The desulfurized vapors together with the reaction products of desulfurization are removed from the reactor by means of a disengaging section (not shown) and are thence conveyed by line II to a fractionator I2 for further processing.

A heavy fraction having an initial boiling point above 400 is introduced to cracking reactor i by line I3 preferably in the vapor form. If desired, a fraction principally in the liquid phase may be introduced by line I4 to reactor l; fractions introduced by lines I3 and I4 being prepared and preheated as described below. Hydrocarbon material introduced by lines I3 and I4 is passed downwardly with a concurrently downwardly moving bed of catalyst. The cracked vapors are removed from the reactor by means of a disengaging section (not shown) and passed by line I5 to a fractionator I6 for further processing.

The downwardly moving beds of catalyst in reactors l and 8 are stripped of high boiling hydrocarbonaceous material in standard purging sections (not shown) by means of steam introduced by lines I'I and I8, the purging steam passing upwardly through the bed and merging with the hydrocarbon material treated. Catalyst is removed from reactors 'I and 8 through appropriate draw-olf devices and passes. by lines I9 and 2I to line 22 where the catalyst streams from the two reactors are merged. The catalyst in line 22 is then conveyed by elevator 23 to line 24 and hopper 25. The catalyst from hopper 25 is charged to a distribution deviceA 26 communicating with a regenerator or kiln 2l. Regenerator 2l may be a vessel equipped with a v plurality' of burning and .cooling sections or zones,

one of which is indicatedin the broken-away section of the regenerator (see article cited above). Air is pumped by 'pump 28x to preheater 29 to which fuel from line 30l is add-ed, Combustion of the fuel in prehe'ater ZELpreheats the air to about 300 F. to 1000" F., which air passes by manifold 32 to lines 33 and thenceto-the'various burning vsections of the regeneratorin amounts controlled by valves 34. If desired preheater 2,9 may be 'by-passed andthe air passed directly to the kiln from the pump Ybyline 3|.; Combustion of the coke is effected by means of the air thus introduced and the spent flue gases so formed are removed by lines 35 t"o\ manifold 36, thereafter The light straight run an indirect heat transfer medium, such as water,

steam, or a molten mixture of inorganic salts,

is fed by lines 38, valves 39 controlling the flow thereof. It is generally preferred to control the 5 amount of air and the amount of heat transfer medium so that the temperature of the catalyst does not rise above a maximum of about 1100 F. The indirect heat transfer medium, after receiving heat in the regenerator, passes by lines 4I to manifold 42 and thence to a heat recovery system 43. The indirect heat transfer medium is cooled in the heat recovery system 43 from which it is removed by line 44 and recirculated to the regenerator by pump 45. Other methods of removing the excess heat in, regenerator 21 may be used such asrecirculation of a portion of cooled flue gases, recirculation of a portion of cooled catalyst and the like. The catalyst after regeneration by removal of at least a portion of the coke deposit (less than 0.5 per cent by weight of coke preferably being left on the catalyst) is removed from regenerator 21 through an appropriate draw-off device and passes by line 46 to elevator 4T which conveys the catalyst to line 2 for charging in the hoppers 3 and 4.

The amount of catalyst diverted to reactor 8 is,

in accordance with the present invention, a'

minor portion of the total amount of catalyst circulating in the system and is preferably less than 25 per cent and may be as low as 1 to 2 per cent, depending on the amount of light fraction to be desulfurized. As discussed above, when reactor 8 has been added to apre-existing system, the diversion of such a minor portion of catalyst from the main stream of catalyst passing through reactor 'i' furnishes catalyst to thedesulfurization reactor while still maintaining, after minor adjustments in the conditions of operation in cracking reactor 1, the same throughput in reactor I as was maintained prior to the diversion. In some of such cases, it may be advantageous to increase slightly the speed of elevator 23, this increase, however, being considerably less than sufficient to furnish the entire amount of catalyst employed in reactor 8.

The catalyst in hopper 4 may, if desired, be cooled by a cooling coil 48. However, under some conditions of operation of reactor 8, particularly those in which an average-reactor temperature in the range of 800 to 900 is desired, the catalyst may be charged from line 2 without cooling and may enter reactor 8 in the temperature range of .950 `to 1050 and be cooled by the light straight run fraction introduced to the reactor so that 55 the average reactor temperature is in the range of. 800 to 900", The light straight run fraction Whichis` introduced into reactor 8 in the vapor Yform hasucient heat capacity relative to that ofthecatalyst, so that the temperature of this 60 fraction is not; excessively increased, the increase being generally of the order of less than 100 F.,' 'such as 50 F. Such a mode of operation affords excellent control of the desulfurizaltion operation and avoids local overheating of 65 the lightgfraction with attendant over treatment or cracking.` In thelatter instance, it is preferred to maintain moderately high space rates (the spac'rate or space velocity being defined as the volume of liquid hydrocarbon material 70 charged tovfthe reactor perhour referred tothe volume of catalyst present in the reactor). Such space rates"v are preferably in the range of 1.0 to 4.

In general, the conditions of operation of re- 75 actor 8 will include average reactor temperatures in the range of 700 to 900 F., space rates in the` range of 0.5 to 5, pressures in the range of atmospheric to slightly above atmospheric, such as 25 pounds per square inch gauge, and catalyst to oil ratios in the range of 0.05 to less than 0.5, and either countercurrent or concurrent flow of catalyst and hydrocarbon material may be employed. However, the combination of Voperating conditions selected from the above ranges is chosen so as to eiect only mild conversion as judged by the amount of lower boiling hydrocarbons produced from the diesel fuel cut. Thus the eiect of selecting an operating condition which tends to produce more severe conversion (such as a high temperature, high pressure, low space rate, or high catalyst to oil ratio) is preferably balanced or compensated for by the selection of at least one other operating condition in the opposite sense. It is therefore preferred, in accordance with the present invention, to choose operating conditions so that a gas oil or diesel fuel cut boiling in the range of 400 to 7507 undergoes a con` version of less than 35 per cent, with a production of less than about 30 per cent butane-free gasoline and less than 2.0 per cent coke, based on the diesel fuel cut charged. In general, the conditions in reactor 8 are chosen so that the production of coke, based on the weight of light fraction comprising a diesel fuel cut charged to the reactor, is in the range of about 0.5 to 2 per cent and the production of gases lighter than butanes, on the same basis, is about 0.8 to 3.5 per cent by weight. When gasoline alone is treated, the amount of coke is lower, being in the range offabout 0.2 to 1.0 per cent while the production of gases lighter than 'butane is about the same or slightly lower than it is when a diesel fuel cut is charged. Generally, conditions are chosen so that the coke produced in reactor 8 is preferably less than about 15 per cent of the coke produced in reactor 1. When small amounts of catalyst, such as to 10 per cent of the total catalyst, are diverted to reactor 8, the percentage of coke may be higher although it is preferred to choose operating conditions such that less than 2.5 per cent coke is deposited on the catalyst in reactor 8. Y

The conditions of operation of reactor 1 are well known to the art and lie generally in the ranges of 800 to 1050 F., catalyst to oil ratios between about 1.5 to 20, such as ratios in the range of 118 to 5, space rates of 0.5 to 3 and pressures of atmospheric to about 25 pounds per square inch gauge. The cracking operation effected in reactor 1 may be of various types; for example, the hydrocarbon material may be introduced substantially completely in the vapor phase or princif pally in the liquid phase or in a mixed liq,uid vapor phase, and the hydrocarbon material may pass either countercurrently or concurrently through the downwardly moving bed of catalyst. These types of operation are well known to the art and further details need not be repeated here. In general, the cracking conditions will be chosen so that at least 30 p'er cent, and preferably more than 35 per cent of the material charged to reactor 1 is converted to motor gasoline. Under such conditions the catalyst discharged from the cracking reactor generally will have a carbonaceous deposit of about 1.5 to 3.0 weight per cent based on the catalyst.

Various catalysts, particularly siliceous cracking catalysts, may be employed in the reactors described above. These catalysts are well known to the art and details of their preparation need not be repeated here. Typical of these catalysts are active or acid activated clays, particularly of the montmorillonite type and synthetic gels comprising silica and at least one other refractory oxide; for example, silica-alumina, silica-alumina-zirconia. silica-zirconia, silica-magnesia, silica-thoria and the like. In accordance with the present invention, it is preferred that such catalysts be prepared or processed so as to yield an active cracking catalyst, such as an activity of above 30 and preferably above 35 measured by the CAT-A test. (The CAT-A test is a commercial test used for the control of the activity of cracking catalysts in which the catalytic activity is expressed as the volume percentage of gasoline referred to the volume of charge stock, produced by cracking a standardized gas oil under standard cracking conditions. Details of this test are given in Laboratory Method For Determining The ActivityOf Cracking Catalysts by J. Alexander and H. E. Shimp, page R,537, National Petroleum News, August 2, 1944.)

In an embodiment of the present invention involving the processing of sour petroleum crude oils. it is preferred to use in connection therewith a sulfur-resistant catalyst (i. e., a catalyst whose rate of decline of cracking activity is not substantially increased by the presence of sulfur compounds in the hydrocarbon material involved). Synthetic colloidal masses having cracking activity, such as the silica containing gels mentioned above show such resistance in contrast to catalysts prepared by known methods from natural clays. However, sulfur resistant catalysts may be characterized (without regard to source or method of preparation) by the fact that such a catalyst shows substantially no decline in cracking activity, as measured by the CAT-A test. when subjected to an accelerated aging test in which the sample of catalyst is subjected to contact with substantially pure hydrogen sulfide at atmospheric pressure at a temperature of 1000 F. for two hours. By the use of sulfur resistant catalysts in accordance with the invention, the equilibrium activity of a fluent catalytic mass circulating through the cracking and desulfurization zones is maintained at a high lever, such as above 25 and preferably above 30, as measured by the CAT-A test. (The equilibrium activity is the activity of the mass of catalyst circulating in a fluent catalyst system and has a value fixed by a dynamic balance between the effect of adding fresh relatively high activity catalyst to replace catalyst lost or removed and the effect of deterioration of the activity of the catalyst in use.)

In one embodiment of the present invention illustrated by an exemplary operation, 7500 barrels per day of a high sulfur crude oil having sulfur content of about 2 weight per cent and a boiling range (ASTM, Engler) of to 1000 F. are charged by line 5| to fractiorator 52 and therein separated into two fractions; about 3400 barrels per day of a light fraction (a wide-cut distillate) having an end point of about 575 to 600 F., although in some instances the end point may be higher, such as up to about 750 F., and about 4100 barrels per day of a heavy fraction comprising the rest of the crude Yoil. The wide cut distillate is removed as an overhead product through line 53 and the heavy fraction as a. bottoms product through line 54. The wide-cut distillate may then be charged to fractionator 55 in accepte tween 50 to 250 F. but such boiling ranges lie 5 within the limits stated. Depending upon the needs of the particular refinery, either the straight run gasoline or the straight run diesel fuel may be sent to storage through lines 58 and 59, respectively, by means ofthe proper manipu- 1Q lation of valves 6| and 92, or 6,3 and 64. Alternatively, fractionator 55 may be by-passed by means of proper manipulation of valves 61 and 68 and the overhead from fractionator 52 passed by line 69 directly to line 10 for desulfurization in 15 reactor 8.r The charge to the desulfurization reactor, which may consist of all of the material in the crude oil boiling below '150 F., or the straight run diesel fuel, or either the straight run gasoline alone, is passed through heating coil 1| 20 in furnace 12 and thereafter passed by line 9 to reactor 8 as previously described. The treating of straight run gasoline alone is particularly effective when the crude oil has a low sulfur content such as below 1.0 Weight per cent. If de- 25 sired, steam from line 13, preheated to a desired temperature, may be added to the charge to the desulfurization reactor by opening the valve 14,

the amount thus added being generally less than 25 weight per cent of the hydrocarbon material 30 charged to the reactor.

In the exemplary operation, the entire wide-cut distillate, preheated to a temperature between 750 and 850 F., is charged to the desulfurization reactor which is operated at an average temperature of between 800 and' 35 40 tween 0.8 and. 1.5, suchv as about '1.2. rIhe light fraction after desulfuriza'tion, as described above, is passed by line I into fractionator I2 in which it i-s separated into aY low sulfur gasoline,

fractionator as an overhead fraction by line 15 and thereafter is appropriately stabilized and prepared for marketing by conventional refining methods, such as washing "with a .solution of caustic. `Desu1furized diesel fuel is removedl 50V from fractionator I2 by line 16 as a side cut while any material boiling above the diesel range is removed from the bottom of the iraction'atorV by/ line 11. By means of appropriate manipulation of valves 18 and 19 or.8I and v82, thedesulfurized 55 diesel fuel and the bottoms, fraction may be sent either to storage` or may be included in the charge to the cracking reactor as hereinafter described. In the exemplary operation, about 1900 barrels per day of motor gasoline having a 90 per cent 60 boiling point (ASTM) of 390 F. and 1310 barrels. per day of a diesel fuel out having l0 per cent and 90 per cent boiling points (ASTM) of about 410 and 560 F., respectively, are produced. vThe motor gasoline so produced has a clear octane 65 `ter as a dicsel engine fuel` is substantially unchanged.

The operation effectively reduces the sul 70 The .portion of crude which is removed from lfractionator 52 by line 54 passes by line 83 to heating coil 84 and a furnace 85 'in which it is flieat'ed to a temperature in the range of 800.' to

900 Fg In addition to the portionof the crude boiling above the wide cut distillate, the material in line 83 may alsoinclude material desulfurized ,in reactor 8, such as all or a portion of the desulfurlzed diesel vfuel introduced by lines '88 and 81 to line 83, or it may include the bottoms fractibn nomine-materia; desuuurizea mreactor s introducedby lines 1.1-and 81 to line 83, or it may contain an` untreated diesel fuel or gas oil outv introduced by lines 51,88 and 81 or it may con# tain a recycle gas oil cut introduced by lines 99 and 81 to line 83. Thus, for example, the hydrocarbon material in line 83 may comprise 4100 barrels per day of the bottoms fractionfrom fractionator 5 2, 510 barrels vper day of hydrocarbon material from the fractionator I2 and 5310 barrels per day of a heavy gasoil in line 90, which gas oil is obtainedfrom the products of cracking in reactor 1.' YIn ordertoaid in the subse. quent volatilizaton of the material in line 83 and to prevent .cok'ing inthe furnace, steam maybe added to `the material in line "83 through line 89 by openingvalve 9|. The hydrocarbon material in line 83 after -passage through furnace 851s Ncharged through line 9T to` a tar separatorli f Y from which' a vaporized overhead fraction is rel moved by liney 94 and an unvaporzed liquid fraction removedby line 9.5, which fractionmay.

Afor example, be about 23pe1f cent of the charge introduced by 'line 92. The unvaporized liquid fraction may be directed to'storage through'line 96 by opening valve 91 orV it may-be directed to a deasphaltizing zone 98fby openingyalvev 99 and passing it through line I0|-.-Indeasphaltizing zone 98 which may employ propane deasphaltizing or vacuum distillation to remove the heavy asphaltic material, the material from line |0I is separated into catalytic cracking stock which is A removed from the deasphaltizing zone 98 by line generally below 0.05 per cent, 1s removed from the 45 |02 and the asphaltic fraction which is removed from this zone byline |03.- When propane fdeasphaltizing is usec, as in theexeinplary operation, the "conditions of deasphaltization are selected to produce 1370 barrels per day`of a clean charge stock having an end point of about'1100 F; The overhead fraction from the tar separator Y in line 94 and the deasphaltized cracking stock in line |02 are passed through heating coils |04 and |05 in furnace |06 and thence charged to reactor 1 by lines I3 and I4. The hydrocarbon material cracked in reactor 1 under the conditions describedfabove is fractionated bylfractionator I6 so as to produce a cracked gasoline fraction amounting, in the exemplary operation, to about 35 to 70 volume per cent of the fresh oil feed. introduced to reactor 1. The gasoline from the fractionator in line I 01 is thereafter appropriate'- ly processed such as by stabilization and removal of fixed gases and by Washing with a solution of caustic, A light gas oil fraction is removed from g I -fractionator I6 by line ||0, a, heavy gas oil frac'- tion by line |08 and a bottoms fraction by line |09. The heavy gas oil fraction may, if desired, be recycled to'the cracking reactor l by means of unes so and a1,.va1ves aan and ua being ap-I propriately manipulated. i

ln order 'to illustrate the present invention but not'to be construed as a limitation thereof, the

75 following specific examplesme given:

tion and tarry bottoms in a tar-separator, the

tarry bottoms deasphaltized using propane, and the deasphaltizedsxnaterial combined with the tar separator overhead'to `yield a heavy fraction for cracking. The properties of the crude oil and liquid fractions were as follows:

1 Vacuum distillation corrected to atmospheric pressure.

The light fraction and the heavy fraction were separately charged to reactors containing moving beds of freshly regenerated active cracking catalyst having less than 0.2 weight per cent of residual carbon thereon. The catalyst used was in the form of beads of calcined synthetic 10W a1- kali silica-alumina hydrogel prepared in a manner knownto the art and having a CAT-A activity index of about 33. The light fraction was charged to the bottom of a desulfurization reactor in counter-current relationship to the moving bed of catalyst; the heavy fraction being charged to the cracking reactor in mixed phase condition at the top of the catalyst bed for concurrent ow with the moving bed of catalyst. 'I'he temperature of the catalyst charged to the desulfurization reactor was about 755 F., which is approximately 220? F. lower than the average temperature of the catalyst following regeneration and represents a removal of 110,000 B. t. u. per ton of catalyst by cooling. The conditions of operation are given in the following table:

TABLE 1B Operation Desltlilgriza Cracking Light Heavy Charge Fraction Fraction Space rate. total charge l. 2 1.21 Fresh fced 0.50 Recycle gas oil 0. 71 Catalyst to oil ratio, based on total charge 0.4 1.53 Temperatures, F.:

Catal st inlet 755 975 Oil in et 750 805 Average of reactor 735 865 Catalyst outlet-- 7 855 Pressure, pounds/sq. in. gauge 10 l0 Catalyst circulating through reactor (tons/hour) 8 100 Coke deposited on catalyst, weight per cent based on catalyst l. 3.0 C; and lighter, weight per cent oi total oil charged 0. 9 Coke. weight por cent of total oil charged. 0. 4, Liquid recovery, volume per cent of charge 102. 2 94. 0

Catalyst was removed from the desulfurization reactor and from `the cracking reactor and regeneration eiected in the type of regenerator referred to above. under conditions such that the residual coke was less than 0.2 weight per cent; the catalyst being thus rendered suitable for reuse in the desulfurization and cracking reactors.

The products from the desulfurization and cracking reactors were fractionated separately; the yields and properties being given below. The properties of the straight run gasoline present in the untreated light fraction are given for comparison.

TABLE IC Desulfurzatron Diesel fue] cut Gasoline l (boiling above I gasoline) Properties In In Prod- In In Prod- Feed uctl Feed uct Gravity, API 60.1 58.5 36. 5 35. 8 Distillation, ASTM,

Intnl 124 130 412 412 178 183 442 441 262 262 405 482 333 335i 553 547 359' 38S 581 034 50. 4 58. 2 58. 68. 0 67. 6 77. 2 50. 7 59. 3 57. 5 68. 9 3 cc. TEL.-. 67.3 78. 2 Sulfur, weight percent. 0. l2 0. 02 0. 93 0. 57 Anilno Point, F 143 144 Diesel Index 52. 3 5l. Yield, Volume percent of charge l. 49. 2 58. 2 49. 6 41.

l Based on removal of butanes and lighter; all gasolines washed with a solution of caustic. 1

2 Based on butano-free lecd stock.

TABLE ID Craclcmg Light Heavy Properties Gasoline l Catalytic Catalytic Gas Oil Gas Oil I. Gravity, API.. 56. 5 18. 2 0. 3 Distillation, ASTM F.:

Initial 94 442 500 132 462 590 242 476 742 378 504 950 End Point 4m 530 95% at 990 Octane Numbers R--M, clear-- 80. l +1 cc. T 82. 5 i +3 cc. TEL. 84. 4 CRF-R, clear.-- 91. l +1 cc. TEL.- 94. 5 +3 cc. TEL 97.3 Reid vapor pressure, po ds per sq. in l0 Sulfur, weight percent 0. 18 2 67 3. 40 Amline point, F 25 103 Diesel index 4. 5 Yicld, volume percent oliresb feed 63. 8 4. 6 l0. 6

l Washed with a solution of caustic.

By operating the desulfurization and cracking reactors in conjunction with a single regenerator under the above conditions, the catalyst from the desulfurization reactor, which is only about 7% of the total catalyst, adds only 2.6% to the total amount of coke burned, and, although F. cooler than the catalyst from the cracking reactor, lowers the temperature of the latter only 10 F. when admixed therewith.

'I-he gasoline from the desul'furization and cracking operations, when blended in amounts proportional to the relative amounts of the charges in thecrude oil and with the addition of 3 cc. TEL, yield a gasoline having about 83.0

"a CFR-M and 89. CFR-R. A gasoline blended in 13 similar manner from the untreated straight run gasoline described in Table IC and the catalytically cracked gasoline has an octane number l 5 (with 3 cc.TEL') in contrast to a blend of unn treated and cracked gasoline blended on thesame Crude oil from the Slaughter eld (West basis which has an octane number (CFR-M) o f Texas) was distilled to produce the fractions 76.8 (with3cc. TEL).

rties:

' f'. having the following prope 1 6 i MPICE m TABLE IIA diesel fuel cut was prepared from the crude/` ioil of Example II by distillation and had the fol- Pmpertles l Llglomcin I lownlg properties:

15 -TABLEIIIA v Gayle, API -B--L 525 .5 Y Gravity, "A1=1 AA -v 32.3 ffgggg'tgtf; g 12 wof M1333A Boiling range, ASTM F v. 464 to 656 Octane numher f 50 9 Sulfur, lWe1ght percent-; 1.43 Cma cr" et 2:::222222: Anillne point, F- .f i. 140 Yield, volume percent-; 3&5 `48.9 Q0 Diesel index 45.2 Cetane 2knumber i 48.6

'Ihe light fraction was desulfurizedand the heavy fraction cracked in a similar manner, including type and activity of catalyst, td that described in connection with Example I except the temperature 0`f the catalyst charged toi-both -Y operations was in the rangeof 940 to 975 F; (approximately the exit temperature of the regenerator) and the light fraction was passed, Catalyst to 011 ratio g 0,32 through the reactor in concurrent relationshipr-BO TeggperatresFJf t 2 to the moving bed of catalyst. The conditions .Catalyst inlt (estimated) 970 of the operations were as follows: 2 0i1"in1et 355 Average of reactor l 840 TABLE IIB catalyst outlet 2- 830 2 35 catalyst circulation, tons/hoer1 5 Operation Destlilllfi' Cracking Coke deposited on catalyst, weight percent based on catalyst Y 2.4 Ca and lighter, weight percent of oil charged 1.8 Charge Liglitom Heat'nfrac' Coke formed, Weightfpercent o` f oil charg'ed 0.9

K 40 1 Based on 12,000 barrels of crude oil 'charged per day. spalgrffffealchafge 1-6 g: The operation produced a synthetic` crude Recycle gos oil. 1.57 which, when distilled; yielded 22.5 volume perggggftfmsed ontotalchage# 0-41 208 cent (based on original cut) of motorgasoline Catalyst inlet 94o :om 94o to 975 having an octane number (CFR-M) of 78.8 (clear) ggelrgeF-f--r-c-t g ggg 45 and 83.3 (with 3 oo. TEL) and 74.5 volume per- Caialyst ouden 84o 895 cent (based on original diesel cut) of desulfurized gslgg' gggigggfgl diesel fuel having the following properties:

reactor 1 8. 5 250 Coke deposited on catalyst, Weglltper v TABLE IIIC i ofir;antennae: f ffl 50 Gravity, API 33.2.6 Bolling range, ASTM "F 460 to 680 l Based on a crude oil charge o! 12,000 barrels per day. Sulfur weghto percent -i L09 As in the previous example, regeneration of the lllegt F``.' *2"*- gli catalyst removed from the desulfurization and l Cetane mimi-3; 49's from the cracking zones was eiected in a regeln-' 5F s I erator whose temperatures were controlled rby in: direct heat transfer. In the present case, mixfture of the two streams of catalyst from `th`desulfurization and cracking zones results in vrtually no change in the temperature of the cata` lyst from the cracking zone (less than 2 F.) and' the coke on the catalystfrom the desulfurization zone adds less than 1% to the total amount of coke burned in the regenerator.

The desulfurized light fraction was distilled yield 94 volume per cent of debutanized motor gasoline, having a boiling range of 140 to 408 F. and an unleaded octane number (CFRf-M) of 56.2 and an octane number of 74.5 with 3 cc. TEL. Thesynthetic crude from the cracking operation v yielded, on distillation, about 60.5 volume per cent Vof motor gasoline and 10.5 volume percent of fuel oil (based on vthe amount {of fresh oil charged to the reactor), the motor gasoline having ari octane number (CFRf-M) of`81 (clear) and l85.6 (with 3 cc. TELL blended from the desulfurized and cracked products in the relative proportions in which they were produced has. an octanenumber (CFR-M) of 81.2

fPheabove cut was contacted in a pilot plant withicatalystof the type described in Example I in an operation equivalent tothe following con- `2:'`ditions ina commercial size' moving bed reactor:

's T ABLE H113 When the commercial size desulfurization re` ample II, there isvproduced not only a desulfurized dieselfuel :fraction of as good.v engine quality vas the virgin4 fraction, but also a quantityof high octane gasoline which considerably augments that'produced in rthe cracking reactor.

In the specification, the fraction boiling between 400" and 750 F. has, for-convenience and brevity, been referred to a diesel fuel fraction. It i-stobe understood, however, that this fraction may be usedjor other purposes where its composition and boiling range lare suitable. Thus all or a part of the 400 to 750 F. fraction may be used I' l as a'tractor fuel, fuel for jet engines and gas turbines, a burning distillate or kerosene, a high grade fuel oil and the like.

Obviously many modifications and varisi'tow7 of :s the invention as hereinbefore set forth nay be motor gasoline 15 made without departing from the spirit and scope thereof and therefore only such limitation: should be imposed as are indicated in the ap- -pended claims.

I claim as my invention:

1. The process of refining a, crude petroleum oil having a sulfur content of 1 per cent by weight or greater in the 400 to 1000 F. fraction which comprises fractionating said crude into a rlight distillate consisting of motor gasoline and diesel fuel and a heavy residual fraction, removing the asphaltic portion from said heavy fraction, passing said light distillate through a first conversion zone, introducing freshly regenerated fluent active cracking catalyst to said first conversion zone, maintaining mild conversion conditions in said first conversion zone such that the coke produced from said light distillate is in the range of 0.5 to 2.0 per cent by weight and the amount of gas lighter than butanes produced from said light distillate is in the range of 0.8 to 3.5 per cent by weight, passing the deasphaltized heavy fraction through a second conversion zone, in-

troducing freshly regenerated fluent active cracking catalyst to said second conversion zone in an amount substantially greater than the amount introduced to said first conversion zone, maintaining cracking conditions in said second conversion'zone so as to effect cracking of said heavy fraction to at least per cent of motor gasoline based on the amount of fresh feed to said zone; removing coked catalyst from said rst and second conversion zones, regenerating a mixture of coked catalyst from the first and second conversion zones in a regeneration zone adapted to remove excess heat by indirect heat transfer, removing freshly regenerated catalyst from said regeneration zone, returning freshly regenerated catalyst to said rst and second conversion zones, separating the products from said first conversion zone into gasoline and diesel fuel fractions, separating the products from said second conversion zone into gasoline and other fractions, and blending the gasoline fractions from the first and second conversion zones to yield a gasoline of high lead susceptibility.

2. The process of claim 1 in which the amount of catalyst passed through said first conversion zone is less than 25 per cent of the total catalyst regenerated.

3. The process of claim 1 in which the amount of catalyst passed through said first conversion zone is less than 10 per cent of thev total catalyst regenerated.

4. The process of claim 1 in which the fluent catalyst moves through the two conversion zones and through the regeneration zone as moving non-turbulent beds.

5. The process of refining a crude petroleum oil having a sulfur content of 1 percent by weight or greater in the 400 to 1000 F. fraction which comprises fractionating said crude into a light distillate consisting of motor gasoline and diesel fuel and having an end point below about 750 F. and a. heavy fraction comprising the remainder of said crude, heating said heavy fraction to a temperature in the range of 800 to 900 F. and separating said heavy fraction into a vaporous fraction and an asphalt containing liquid fraction, removing asphalt from said liquid fraction, passing said light distillate through a downwardly moving non-turbulent bed of catalyst in a first convension zone, introducing freshly regenerated fluent active cracking catalyst to said first conversion zone in amounts such that a cata.-

16 lyst to oil ratio of less than 0.5 and greater than 0.05 is produced, maintaining mild conversion conditions in said first conversion zone such that the coke produced from said light distillate is in the range of 0.5 to 2.0 percent by weight and the amount of gas lighter than butanes produced from said light distillate is in the range of 0.8 to 3.5 percent by weight, passing the deasphaltized liquid fraction and said vaporous fraction through. a downwardly moving nonturbulent bed of catalyst in a second conversion zone. introducing freshly regenerated fluent active cracking catalyst to said second conversion zone in amounts such that a catalyst to oil ratio of greater than 1.5 is produced, maintaining cracking conditions in said second conversion zone so as to eect cracking of the total hydrocarbons charged to at least 35 percent of motor gasoline, removing coked catalyst from said rst and second conversion'zones, regenerating a mixture of coked catalyst from the rst and second conversion zones in a. regeneration zone adapted to remove excess heat by indirect heat transfer, removing freshly regenerated catalyst from said regeneration zone, returning freshly regenerated catalyst to said first and second conversion zones, separating gasoline and diesel fuel from the products from said first conversion zone, said diesel fuel having substantially'the same diesel index as that of the straight run untreated diesel fuel and having a substantially lower sulfur content than said untreated diesel fuel, separating gasoline from the products from said second conversion zone, and blending the gasoline fractions from the first and second conversion zones to yield a gasoline of high lead susceptibility.

6. The process of refining a crude petroleum oil having a sulfur content of 1 percent by weight or greater in the 400 to 1000 F. fraction which comprises separating said crude into a light distillate comprising dieselfuel and having an end point below about 750 F. and a heavy residual fraction, deasphalting said heavy residual fraction, passing said light distillate through a downwardly moving non-turbulent bed of catalyst in a first conversion zone, introducing freshly regenerated fluent active cracking catalyst to said first conversion zone in amounts such that a catalyst to oil ratio of less than 0.5 and greater than 0.05 is produced, maintaining mild conversion conditions in said first conversion zone such that the coke produced from said light distillate is in the range of 0.5 to 2.0 percent by weight and the amount of gas lighter than butanes produced from said light.- distillate is in the range of 0.8 to 3.5 percent by weight, passing the deasphaltized heavy residual fraction through a downwardly moving non-turbulent bed of catalyst in a second conversion zone, introducing freshly regenerated fluent active cracking catalyst to said second conversion zone in amounts such that a catalyst to oil ratio of greater than 1.5 is produced, maintaining cracking conditions in said second conversion zone so as to effect cracking of the total hydrocarbons charged to at least 35 percent of motor gasoline, removing coked catalyst from said first and second conversion zones, regenerating a mixture of coked catalyst from the first and second conversion zones in a common regenerationfzone, removing freshly regenerated catalyst from said regeneration zone, returning freshly ,regenerated catalyst to said first and second conversion zones, .separating gasoline and diesel fuel from the products from said first conversion zone, said die;e1

fuel having substantially the same diesel index as that of the straight run untreated diesel fuel and having a substantially lower sulfur content than said untreated diesel fuel, separating ygasoline from the products from said second conversion zone, and blending the gasoline fractions from the rst and second conversion zones to yield a gasoline of high lead susceptibility.

7. The process of renning a crude petroleum oil having a sulfur content of l percent by lweight or greater in the 400 to 1000 F. fraction which comprises fractlonating said crude into a light distillate comprising diesel fuel and having an end point below about' 750 F. and a heavy fraction comprising the remainder of said crude, sep- I arating said heavy fraction into a vaporous fraction and an asphalt containing liquid fraction,

removing asphalt from said liquid fraction, passing said light distillate through a downwardly moving non-turbulent bed of catalyst in a rst conversion zone, introducing freshly regenerated fluent active cracking catalyst to said ilrst conversion zone in amounts such that a catalyst to oil ratio of less than 0.5 and greater than 0.05.15 produced, maintaining mild conversion conditions in said first conversion zone such that the troducing freshly regenerated nuent active cracking catalyst to vsaid second conversion zone in amounts such that a catalyst to oil ratio of greater than 1.5 is produced, maintaining cracking conditions in said second conversion zone so as to effect cracking of the total hydrocarbons charged to at least 35 percent of motor gasoline,

removing coked catalyst from said first and second conversion zones, regenerating a mixture of 18 coked catalyst from the nrst and second conversion zones in a common regeneration zone, removing freshly regenerated catalyst from said regeneration zone, returning freshly regenerated catalyst to said first and second conversion zones, separating gasoline and diesel fuel from the products from said iirst conversion zone, said diesel fuel having substantially the same diesel index as that of the straight run luntreated diesel fuel and having a substantially lower sulfur content than said untreated diesel fuel, separating gasoline from the products from said second conversion zone, and blending the gasolineA fractions from the first and second conversion zones to yield a gasoline of high lead susceptibility.

JOHN E. FORD. Jn.

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

UNITED STATES PATENTS Number Name Date 2,290,580 Degnen et al. July 2l, 1942 .2,377,613 Conn z June 5, 1945 2,409,353 Guiliani et al. Oct. 15, l946 2,414,973 Nelson Jan. 28, 1947 2,432,912 Loeb Dec. 16, 1947 $438,456 Russell et al Mar. 23. 1948 2,450,724 Grote Oct. 5. 1948 OTHER REFERENCES 1,'1943, pages R-563, 564, 566. 557.

Claims (1)

1. THE PROCESS OF REFINING A CRUDE PETROLEUM OIL HAVING A SULFUR CONTENT OF 1 PER CENT BY WEIGHT OR GREATER IN THE 400* TO 1000*F. FRACTION WHICH COMPRISES FRACTIONATING SAID CRUDE INTO A LIGHT DISTILLATE CONSISTING OF MOTOR GASOLINE AND DIESEL FUEL AND A HEAVY RESIDUAL FRACTION, REMOVING THE ASPHALTIC PORTION FROM SAID HEAVY FRACTION, PASSING SAID LIGHT DISTILLATE THROUGH A FIRST CONVERSION ZONE, INTRODUCING FRESHLY REGENERATED FLUENT ACTIVE CRACKING CATALYST TO SAID FIRST CONVERSION ZONE, MAINTAINING MILD CONVERSION CONDITIONS IN SAID FIRST CONVERSION ZONE SUCH THAT THE COKE PRODUCED FROM SAID LIGHT DISTILLATE IS IN THE RANGE OF 0.5 TO 2.0 PER CENT BY WEIGHT AND THE AMOUNT OF GAS LIGHTER THAN BUTANES PRODUCED FROM SAID LIGHT DISTILLATE IS IN THE RANGE OF 0.8 TO 3.5 PER CENT BY WEIGHT, PASSING THE DEASPHALTIZED HEAVY FRACTION THROUGH A SECOND CONVERSION ZONE, INTRODUCING FRESHLY REGENERATED FLUENT ACTIVE CRACKING CATALYST TO SAID SECOND CONVERSION ZONE IN AN AMOUNT SUBSTANTIALLY GREATER THAN THE AMOUNT INTRODUCED TO SAID FIRST CONVERSION ZONE, MAINTAINING CRACKING CONDITIONS IN SAID SECOND CONVERSION ZONE SO AS TO EFFECT CRACKING OF SAID HEAVY FRACTION TO AT LEAST 35 PER CENT OF MOTOR GASOLINE BASED ON THE AMOUNT OF FRESH FEED TO SAID ZONE; REMOVING COKED CATALYST FROM SAID FIRST AND SECOND CONVERSION ZONES, REGENERATING A MIXTURE OF COKED CATALYST FROM THE FIRST AND SECOND CONVERSION ZONES IN A REGENERATION ZONE ADAPTED TO REMOVE EXCESS HEAT BY INDIRECT HEAT TRANSFER, REMOVING FRESHLY REGENERATED CATALYST FROM SAID REGENERATION ZONE, RETURNING FRESHLY REGENERATED CATALYST TO SAID FIRST AND SECOND CONVERSION ZONES, SEPARATING THE PRODUCTS FROM SAID FIRST CONVERSION ZONE INTO GASOLINE AND DIESEL FUEL FRACTIONS, SEPARATING THE PRODUCTS FROM SAID SECOND CONVERSION ZONE INTO GASOLINE AND OTHER FRACTIONS, AND BLENDING THE GASOLINE FRACTIONS FROM THE FIRST AND SECOND CONVERSION ZONES TO YIELD A GASOLINE OF HIGH LEAD SUSCEPTIBILITY.

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