US2682496A - Deashing residual oils with an acid of phosphorus - Google Patents

Description

June 29, 1954 R. w. RICHARDSON ETAL 2,682,496

DEASHING RESIDUAL OILS WITH AN ACID OF PHOSPHORUS- Filed Dec. -7,` 1951 0210;) u??? do# NWSOMN. obl Dumon( 1:0

ydesirable constituents from these oils.

Patented June 29, 1954 DEASHING RESIDUAL OILS WITHAN ACID OF ,PHO SPHORUS Roger W. Richardson, Baton Rouge, La., and Cecil H. Hale, Austin, Tex., assignors to Standard Oil Development Company, a corporation of Delaware Application December '7, 1951, Serial No. 260,392

The present invention is concerned with an improved process for the removal of ash forming constituents from petroleum oils, particularly from petroleum oils remaining after distillation of volatile components. The invention is more particularly concerned with an improved process for the preparation of high quality motor fuels, heating oils and for the. preparation of satisfactory feed stocks for a fluid catalytic cracking operation. In accordance with the present invention, undesirable high ash forming constituents are removed from petroleum oils, particularly from high boiling petroleum oils by an operation which comprises treating these oils with a phosphorous compound followed by the removal of the reaction constituents, preferably with an aqueous solvent.

It is well known in the art to treat mineral oils by various processes in order to remove un- For example, it is known to employ light hydrocarbon solvents, as for example, hydrocarbons such as propane and butane in order to remove undesirable constituents, as for example, asphaltic constituents therefrom. In these operations various temperatures and pressures are employed, as well as various solvent to oil ratios.' It is also known yin the art to use various processes for the removal of gum and ash-forming constituents therefrom. Other processes have been directed toward the preparation of satisfactory high boiling feed stocks for fluid catalytic cracking operations.

`lior example, it is known in the art that crudes contain ash materials which normally comprise compounds of metals such as salts of sodium, silicon, iron, calcium, magnesium, nickel and vana'- dium. These ash constituents are either oil soluble or are so nely dispersed that. they can be settled or filtered out only with great difficulty. When the crudes are fractionated, these compounds tend to be concentrated in the heavier fractionswhich may be employed as cracking feed stocks. This is particularly true of the residuum or bottoms fractions which contain high quantities of ash which it has not heretofore been L case when using clean feed stocks. yAs a matterv of, fact, the catalyst tends to become contaminated or poisoned so quickly When processing residual stocks that replacement costs become 5 Claims. (Cl. 196-50) prohibitive. For these reasons, such residual stocks 'are not normally fed to fluid catalytic cracking units.

It has now been discovered that undesirable high ash forming constituents may be more eiliciently removed from feed stocks boiling in their reduced crude boiling range, providing the oil is heated and treated with a phosphorous compound followed by the removal of undesirable constituents with a solvent, as for example, with an aqueous solvent. The process of the present invention may be readily ,understood by reference to the drawing illustrating one embodiment of the same.

Referring specically to the drawing, a feed oil, as for example, a West Texas crude, is introduced into distillation zone I by means of feed line 2. Temperature and pressure conditions are adjusted in zone I to secure the desired fractionation of the crude oil. Low boiling hydrocarbon gases are removed overhead by means of line 3; a lower boiling hydrocarbon fraction is removed by means of line 4, a higher boiling hydrocarbon fraction is removed by means of line 5, and a somewhat higher boiling fraction is removed by means of line 6. A fraction boiling in the reduced crude boiling range, as for example, in the range above about 600 to '700or F., preferably boiling in the range above 850 F., is segregated as a bottoms fraction by means of line 1. It is to be understood that zone I may comprise any suitable number and arrangement of distillation zones or stages.

In accordance with the present invention, the high boiling oil if cooled is raised to an elevated temperature in a heating zone. preferred to add the compound of phosphorus directly tothe hot oil as it is withdrawn from zone I. Thus the compound of phosphorus, as for example an phosphoric acid is added from line 50 by means of line 5I. The mixture is then passed to treating or soaking zone 9 by means of line I0 wherein the oil and acid are thoroughly mixed by means of mixer II. Any evolved gases are removed from zone 9 by means of line I2. It is to be understood that treating zone 9 likewise may comprise any suitable number and arrangement of stages.

The treated oil is withdrawn from Zone 9 by means of line I3 and introduced into a solvent washing zone I4. The oil is contacted in zone I4 with a. suitable solvent, preferably with water, which is introduced by means of line I5 as steam. Temperature and pressure conditions vin zone Id are adjusted to secure the desired removal of the However, it isy undesirable material from the oil. Water is recycled from the bottom of zone I4 to the top by means of line I6, pump I1, line I8, and spray means I9. Additional water may be added by means of line 20. Washing zone I4 may comprise any suitable number and arrangement of stages.

'Ihe treated and washed oil is removed from zone I4 by means of line 2l and passed into a solvent separation zone 22. The water containing the acid and ash forming materials is removed by means of line 23 while the treated oil free of water and undesirable constituents is removed by means of line 24. This oil may be removed from the system by means of line 25 and used as a heating oil or as a feed stock for various other processes which require that the oil be free or substantially free of high ash formn ing constituents.

However, a preferred adaptation of the invention is to combine the foregoing with a fluid catalytic cracking operation.' As pointed out heretofore, the use of reduced crudes in a catalytic cracking operation has presented problems due to the fact that it has not been possible heretofore to remove ash forming Vconstituents from these high boiling reduced crudes to a satisfactory extent. The presence of these constituents in a feed oil in a iiuid catalytic cracking operation causes excessive formation 'of carbon on the catalyst, thus substantially decreasing the activity of the catalyst. Therefore, in accordance with a preferred adaptation of the present invention, the treated oil free of undesirable iron, vanadium and nickel and other compounds is removed from zone 22 by means of line 24 and introduced into a iiuid catalytic cracking operation. The uid catalytic cracking plant is composed of three sections: cracking, regeneration and fractionation. The ycra-cking reaction takes place continuously in one reactor, the spent catalyst being removed continuously for regeneration in a separate vessel, from which it is returned to the cracking vessel. Continuity of flow of catalyst as well 'as of oil is thus accomplished, and the.

characteristic features of fixed-bed designs involving the intermittent shifting of reactors through cracking, purging, and regeneration cycles `are eliminated.

Regenerated lcatalyst is withdrawn from the regenerator and flows by gravity down a standpipe, wherein asufciently high pressure head is built up Aon the catalyst to allow its injection into the fresh liquid `oil istream. The resulting mixture of oil and catalyst flows into the reaction vessel, in whichgas velocity is intentionally low, so that a Vhigh concentration of catalyst will result. The cracking that Ytakes place resuits in carbon deposition on the catalyst, requiring regeneration of the catalyst. The cracked product oil vapors are withdrawn from the top of the reactor after passing through cyclone separators to free them of any entrained catalyst particles, while the spent catalyst is withdrawn from the bottom of the reactor and is injected into a stream of undiluted air which carries the catalyst yinto the regeneration vessel. The products of combustion resulting from the regeneration of the catalyst leave the top of this vessel andpass through a series of cyclones where the bulk of the entrained catalyst is recovered. e

The regenerated catalyst is withdrawn 'from 'the bottom of the vessel to complete its cycle.

Again referring specifically to the drawing, in accordance with -a preferred adaptation of `the present invention, the treated oil removed by means of line 24 is introduced into a catalytic cracking zone 25.

Temperature and pressure conditions in cracking zone 25 are adjusted to secure the desired conversion of the feed oil. Cracked products are removed overhead from zone 25 by means of line 25 and passed into a fractionation zone 21. Temperature and pressure conditions in fractionation zone 21 are adjusted to remove overhead by means of line 28 hydrocarbon constituents boiling in the gasoline and lower boiling ranges. lThis stream is passed to a stabilizing unit where a gasoline fraction of the desired Volatility is segregated. A heating oil fraction is removed by means of line 29 while a fraction boiling in the cycle oil boiling range is removed by means of line 30. A bottoms fraction is removed by means of line 3l and handled as desired. Spent catalyst is removed from the bottom of zone 25 by means of line 32 and passed into a regeneration zone 33 by means of line' 34. Sufiicient air is introduced into the system by means of line 35. Regenerated catalyst is removed from the bottom of zone 33 by means of line 3S and passed to the reactor along with the feed by means of line 24.

Since the viscosity of the residual oil is relatively high, a preferred mode of operation is to add a lower boiling oil, as for example, a gas oil, to the residual oil by means of line 52 as the residual oil passes into the water washing zone I4. Under certain conditions it may also be desirable to add a lower boiling oil to the residual oil in line 24 by means of line 53.

The invention is broadly concerned with the removal of ash forming constituents from high boiling residual oils. The invention is 'specifically concerned with an improved process for the production of motor fuels utilizing a fluid catalytic cracking operation, wherein the feed to the catalytic operation comprises a residual oil. In accordance with the present invention the ash forming constituents in residual oils are removed by heating the residual oils to elevated temperatures, below which cracking occurs, in

the presence of a small amount of a ,compound of phosphorus Yfollowed `by the removal of undesirable constituents utilizing a solvent. It is preferred that the compound of phosphorus comprise an acid of phosphorus. However, oxides of phosphorus may also be utilized.

When utilizing an acid of phosphorus the concentration of the acid should be in the range from about 60% to 100%. A preferred concentration is in the range from about 89% to 90%. The quantity of lacid employed may be in the range from .05% to y10% by volume based. upon the feed. `A preferred `amount employed is .in the vrange from about 1% to 3% by volume.

The preferred feeds for use in conjunction with the present invention are residual oils wherein the gravities are below about 15 API, preferably below 'about 12 API. These oils should boil preferably above about 600 to 700 F.

Treating temperatures forcontacting the compound of phosphorus and the oi1 are in the range of about 500 F. to 800 F. Preferred treating temperatures are yin the range from about 600 F. to 700 F. The time of contact likewise may Vary appreciably, as for example, from about V15 minutes to 6 hours. Preferred ytimes of Vcontact are in the range 'from about 2 to 3 hours.

In addition to or in place of water washing,

through slightly ralkaline 'mater-iai, or filtered,

or a combination of these treatments may be used. Regardless of the method used, it is important that the ash constituents which have been agglomerated and/or made water soluble by the heat treatment with phosphoric acid be removed. Water washing is generally suiiicient, but any one or a combination of the other methods may be used instead or in conjunction with the water washing. Under some conditions, it may be desirable to form an emulsion and then break it, and subsequently remove the water containing the soluble catalyst poisons.

Thusby the present invention, residual stocks which would otherwise have to be sold as low cost, heavy fuel oil or otherwise used as low grade, heavy products are converted to valuable catalytic cracking feed which may be cracked over catalysts, without undue contamination, to yield high octane gasoline and other valuable products normal to the fluid catalytic cracking operation.

As discussed above, the invention is particularly concerned with an improved operation which comprises the treatment of a reduced crude by contacting it with a compound of phosphorus, removing a residue and utilizing the treated stock to secure an improved catalytic cracking operation. It is well known in the art to produce cracked naphthas by a uidized solids catalytic operation wherein the cracked product comprises constituents boiling in the motor fuel boiling range, as for example, below about 430 F. The cracked product also comprises normally gaseous constituents, as for example, those containing three carbon atoms and less in the molefi cule. The iluidized solids technique for processing feed fractions, as for example, gas oils, heavy residuums and other feed stocks for the production of hydrocarbon fractions boiling in the motor fuel boiling range is a conventional one. -I

As discussed heretofore, the system of a fluidized solids technique comprises a reaction zone and a regeneration zone, employed in conjunction with a fractionation zone. The reactor and the catalyst regenerator are arranged at approximately an even level. The operation of the reaction zone and the regeneration zone is conventional, which preferably is as follows:

An overflow pan is provided in the regeneration zone at the desired catalyst level. overflows into a withdrawal line which preferably has the form of a U-shaped seal leg connecting the regeneration zone with the reaction zone. The feed stream introduced is usually preheated to a temperature in the range from about 500 to 650 F. in exchangers in heat exchange with regenerator flue gases which are removed overhead from the regeneration zone, or with cracked products. The heated feed stream is withdrawn from the exchangers and introduced into the reactor. The seal leg is usually sui'ciently below the point of feed oil injection to ,prevent oil vapors from backing into the regenerator in case of normal surges. Since there is no restriction in the overflow line from the regenerator, satisfactory catalyst flow will occur as long as the catalyst level in the reactor is slightly below the catalyst level in the regenerator when vessels are carried at about the same pressure. Spent catalyst from the reactor flows through a second U-shaped seal leg from the bottom of the reactor into the bottom of the regenerator. The rate of catalyst now is controlled by injecting some of the air into catalyst transfer line to the regenerator.

The catalyst The pressure in the regenerator may be controlled at the desired level by a throttle valve in the overhead line from the regenerator. Thus, the pressure in the regenerator may be controlled at any desired level by a throttle valve which may beoperated, if desired, by a differential pressure controller. If the pressure differential between the two vessels is maintained at a mini,- mum, the seal legs will prevent gases from passing from one vessel into the other in the event that the catalyst flow in the legs should cease.

The reactor and the regenerator may be designed for high velocity operation involving linear superficial gas velocities of from about 2.5 to 4 feet per second. However, the supercial velocity of the upilowing `gases may vary from about l-5- and higher. Catalyst losses are minimized and substantially prevented in the reactor by the use of multiple stages of cyclone separators. These cyclone separators are usually from 2 to 3 and more stages.

Distributing grids may be employed in the reaction and regeneration zones. Operating temperatures and pressures may vary appreciably depending upon the feed stocks being processed and upon the products desired. Operating temperatures are, for example, in the range from about 800 to 1000 F., preferably about 850- 950 F., in the reaction zone. Elevated pressures may be employed, but in general pressures below 1'00` lbs. per sq. in. gauge are utilized. Pressures generally in the range from 1 to 30 lbs. per sq. in. gauge are preferred. A catalyst holdup corresponding to a space velocity of 1 to 20 weights per hour of feed per weight of catalyst is utilized. A preferred ratio is 2 to 4. Catalyst to oil ratios of about 3 to 10, preferably about 6 to 8 by weight are used.

The catalytic materials used in ythe fluidized catalyst cracking operation, in accordance with the present invention, are conventional cracking catalysts. These 'catalysts are oxides of metals of groups II, III, IV and V of the periodic table. A preferred catalyst comprises silica-alumina wherein the weight per cent of the alumina is in the range from about 5 to 20%. Another preferred catalyst comprises silica-magnesium where the Weight per cent of. the magnesia is about 5% to 20 These catalysts may also contain a third constituent, as for example, ThOz, W03, MoO, B60, BizOs, CdO, U03, B203, S1102, F6203, V205, MnO, CrzOa, CaO, T1203, MgO and CezOs present in the concentration from 0.05% to 0.5%, The size of `the catalyst particles is usually below about 200 microns. Usually at least 50% of the catalyst has a micron size in the range from about 20-80. Under these conditions with the superficial velocities as given, a liuidized bed is maintained wherein the lower section of the reactor, a dense catalyst phase exists while in the upper area of the reactor a dispersed phase exists.

The above described operation as pointed out,

has not been entirely satisfactory for cracking heavy oils such as a reduced crude due to execssive formation of carbon on the catalyst. However, by combining the phosphorus and water treating stages with the catalytic cracking stage, an improved operation results when using feed stocks of this character. The process of the present invention may be further understood by the following examples, further illustrating the same.

Example I A non-desalted South Louisiana crude was distilled -to. about y2.4% ybottoms andthe residuum thus obtained-was heated :with 85% II3PO4 to various temperatures. The residuum had the following inspections:

Feed 2.4% South Louisiana The products were dilutedwith gas oilto reduce the viscosity and water-washed by injecting steam through a frittedtube. The water washing resulted in the formation of some water-in-oil emulsion which was broken by treatment with an electric field and allowed to settle. The product was analyzed for total ash and for the particuu larly potent catalyst poisons, iron and vanadium oxides. The following results were calculated on an added gas-oil-free basis:

Poums/Thlousand ,y arre s Run No. Haroi Trent mtg Ash FezOs V205 Feed No.... 1, 72B 69 3 None (but sample Yes... 320 4 washed). 2 Hrs.. 600 F., Yes... 50 5 3 2% H3PO4. 1 Hr., 720 F., 2% Yes... 51

HgP O4. 2Hrs., 000 F., 1% Yes... 78 1 1 Example II A 10 residuum from desalted South Louisiana crude was heated with 2.0% of 85% H3PO4 for 2-6 hours at GOO-675 F. in the same manner as in Example I. After the treatment with IPOi, the material was water washed, the water was decanted off and the product analyzed for ash. The following results were obtained:

Residua from (I) West Texas and (II) a mixture of Louisiana and Texas crudes were treated with 2% of 85% H3PO1 at 600 F. for two hours and water Washed in accordance with Example I with the following results:

The West Texas residuum had thefollowing inspections Feed 16% West Texas Atmos.

Residuurn Gravity, API 11.0

Conradson Carbon, Wt. Percent 14 Viscosity, SSF at 210 F 186 Pour, F 90 Carbon, Wt. Percent... 85.6

Hydrogen, Wt. Percent l1.

H/C Atomic Ratio 1. 54

Sulfur Wt. Percent..

sh, Wt. Percent ASTM Distillation Initial, 714 at F 843 The results ofthe operations were asy follows:

H PO P. T.RB..ii Product ,Run a 4 Watep esi uum Feed Treat- No. ment Wash Ash F6203 V205 1.... 16% West Texas No No.. 372

Residuum Yes-.- 68 0.3 29 do.. Yes--. 57 117 Mixed La. and No-.. 1,050

Texas Residua. 5.- do No Yes..- 232 7 39 6. .do Yes Yes... 132 0.3 1

The above examples clearly show that oil soluble ash Vconstituents are removed from residual stocks lby heating the residua with 1 to 2% HsPOt at temperatures of GOD-700 F. followed by water' washing. The iron and vanadium constituents of the ash are significantly reduced.

"What is claimed is:

1. Improved process for the production of hydrocarbon constituents boiling in the motor fuel boiling range from a feed oilboiling above about 600F. which comprises contacting said feed oil inv an initial stage with from about 0.5 to 10% by weight of anacid of phosphorus at an elevated temperature, removing the oil and contacting the same in a secondary stage with a washing solvent, separatingthe residue from the treated oil and then contacting said oil with a uidized cracking catalyst at elevated temperatures and pressures adapted to crack the oil and produce hydrocarbon constituents boiling in the motor fuel boiling range.

2. Process as defined by claim 1 wherein the feed oil is an oil which boilsabove about 860 F.

3. Process as definedby claim l wherein the temperature employed in the initial zone wherein the oilis contacted with an. acid of phosphorus is in therrange from about V500" to '700 F.

4. Process for the production of hydrocarbon constituents boiling in the motor fuel boiling range which comprises treating a feed oil having a gravity in the range from 4about 6 API to 15 API and boiling above about 60W-F.; with from about 0.5 to 10%fby Weight of an acid of phosphorus having a concentration in the range from about to 90% at a temperature in the range from about 600 F. to 700 F., removing the treated feed oil and washing lthe same with water in a temperature inthe range from 600 F. to 700 F., separating the water .and rthereafter subjecting the said feed oilto a temperature in the range from about 800 F. to 1050 F., and ata pressure below about lbs. per sq. in. ganga-to the effect of a cracking catalyst, removing a cracked product and separating a fraction boiling in the motor fuel boiling range.

5. Process as'dened by claim 4 wherein the amount of acid of lphosphorus utilized is in the range from about 1% to 3% by weight.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,709,315 .Lachman Apr. 16, 1929 42,187,741 Houdry Jan. 23, 1940 FOREIGN i PATENTS Number Country Date v529,8"13 Great Britain .Nov. 29, 1940 OTHER REFERENCES Aging of Cracking Catalysts,.G. A. Mills, vol. 42, Ypages '182487, Ind. and -Eng. Chemistry, January 1950.

Claims (1)

1. IMPROVED PROCESS FOR THE PRODUCTION OF HYDROCARBON CONSTITUENTS BOILING IN THE MOTOR FUEL BOILING RANGE FROM A FEED OIL BOILING ABOVE ABOUT 600* F. WHICH COMPRISES CONTACTING SAID FEED OIL IN AN INITIAL STAGE WITH FROM ABOUT 0.5 TO 10% BY WEIGHT OF AN ACID OF PHOSPHORUS AT AN ELEVATED TEMPERATURE, REMOVING THE OIL AND CONTACTING THE SAME IN A SECONDARY STAGE WITH A WASHING

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