US2893943A - Converting metals-containing oils - Google Patents

Description

.FuHy 7, 1959 B. vxGNovlcH coNvERTrNG METALS-CONTAINING oILs Filed April s, 1956 CUNVERTENG METALS-CONTAINER@ OILS Barney Vignovich, Borger, Tex., assignor to Phillips Petroleum Company, a corporation of Delaware Application April 3, 1956, Serial No. 575,793

7 Claims. (Cl. 208-78) This invention relates to the conversion of metalscontaining oils.

In one of its aspects, this invention relates to the conversion of hydrocarbon oils containing metal contaminants which deposit upon a catalyst which is employed by first treating the said catalyst with a metals-free cokable material to lay down thereon a coke which does not contain metals and then employing said partially spent catalyst which is still considerably active to convert the said metals-containing oil.

It has been observed that the introduction of a heavy residuum into contact with an active cracking catalyst, when said heavy residuum contains a substantial metals contaminant content, results in a high metal content on the catalyst which then acts as a dehydrogenation catalyst increasing not only the coke lay down but decreasing the proportion of desired products obtainable from the said oil. Also, when other oils are also cracked with the said catalyst, these too result in :greater coke production with concomitant decrease of yield of desirable fractions. y

It is an object of this invention to provide a method for the cracking of metals-containing oils. A more specie object is the provision of a method for catalytically converting a metals-containing oil. A still further specic object of the invention is to provide a method for the conversion of metals-containing oils employing a catalyst which is also employed for the conversion of oils which are free from metal contaminants.

Other objects, aspects, as well as several advantages of the invention are apparent from this disclosure, the drawing, and the appended claims.

It has now been found that if the oil which is substantially free from metals-contaminants is rst converted in the presence of the fresh or regenerated catalyst to provide a lay down of coke thereon and then this is followed by converting the metals-containing oil, say a heavy residuum, with the partially spent yet active catalyst which is thus obtained that, upon regeneration, it is possible to burn off from the catalyst a suflcient quantity of coke that it will take with it metals-contaminants which have been laid down during the conversion cycle by the heavy residual oil.

Thus, according to this invention, there is provided a method for the catalytic cracking of an oil containing metals which conventionally upon contact of the oil with a catalyst are deposited thereon resulting in an undesirable accumulation on, or alteration of, the activity of the said catalyst at least with respect to the type of reaction it will cause to occur when it has been regenerated and is again used, which comprises laying down coke upon said catalyst by contacting the same with a substantially metals-free cokable material under conditions to cause a coke down upon said catalyst, continuing said contacting until a substantial and desirable coke lay down is obtained upon said catalyst and then contacting said metals-containing oil with said catalyst, having said coke lay down thereon, under oil conversion 2,893,943' Patented July 7, 1959 conditions and affecting conversion of said metals-containing oil with concomitant lay down of metals and further amount of coke on said catalyst which further amount of coke lay down together with the metals contaminants are then burned olf the catalyst during the regeneration step (along with a portion of the first-laiddown coke), thus avoiding accumulation of undesirable metals contaminants upon said catalyst thereby throughout any desired number of cycles maintaining said catalyst active for the type of conversion which is desired.

It will be noted by one skilled in the art in possession of this disclosure that my invention lits in nicely with earlier knowledge and lends itself to ready adaptation to existing units, especially uidized cracking units. Thus, for example, it is known that a gas oil is an oil which is more refractory than a topped crude or a heavy residulun obtained from a vacuum distillation. Therefore, my invention is advantageously applied to such oils, as described herein, because the active catalyst when it is still considerably more active than required for desirably converting a heavy residuum is first contacted with the more refractory gas oil. Then, the partially spent catalyst when it has at least to an extent converted the said gas oil is contacted with the heavy residuum, which as noted, does not require the full activity of the catalyst which it possesses when it has just been regenerated.

It will be noted that according to the invention at each cycle of regeneration whatever metals containing coke has accumulated upon the catalyst is burned therefrom. Furthermore, it will be noted that there is always present on the catalyst a lay down of coke which separates the active surfaces of the catalyst, so to speak, from the contaminating metals. Thus, when the catalyst is regenerated, the outer layer with the metals is burned off first and thusly does not give the metals anything to cling to so they are sluffed olf and are removed 'with the combustion gases.

For example, a regenerated catalyst with about 0.3 `weight percent carbon is employed to crack a clean gas oil and coke is deposited throughout the material up t0 about l percent by weight. Then this partially spent catalyst is used to crack a metal-containing oil thus depositing metal-containing coke upon the catalyst to say a total coke content of approximately 1.5 percent by Weight. Upon regeneration, residual coke, in one embodiment of the invention, will be approximately 0.3 weight percent.

To the extent that metals contaminants are prevented from adhering to the catalyst throughout repeated cycles, a benefit is gained additional to that of obtaining the desired type of conversion. Thus, for example, a lower rate of catalyst addition and withdrawal can be used to control metal level, if any, while upgrading crude bottoms from low value into high value saleable products and this as noted will be without penalty on the gas oil cracking.

Although this invention is primarily described as related to a fluidized cracking operation, it will be obvious that it is applicable to catalytic processes generally, in which a burnofr type regeneration is employed and in which it is possible to lay down, as it were, layers of metals-free or contaminant-free coke followed by a layer of coke containing the metals contaminant. Thus, one skilled in the art in possession of this disclosure will be able readily to adapt the modus operandi of the invention to other reactions. Of course, the modus operandi is also applicable to stationary and moving bed type of catalysis.

In the following description, it is possible to substitute other reactants or oils for those which are given by way of specific example.

Referring now to the drawing, a gas oil is fed by conduit 1 into oil preheater 2 wherein it is preheated to a desired cracking temperature in the `range of 400 to about 750 F. In this instance, the gas oil is heated to approximately 720 F. rIlhe gas oil is passed by way of conduit 3 into riser conduit 4 wherein it is admixed with iluidized regenerated catalyst from standpipe 5. The flow of catalyst is regulated by way of gate valve 6. The catalyst in standpipe 5 is, of course, hot (1020 to l100 F.) and the heat content of the catalyst and of the oil cause immediate conversion to be initiated. Core version continues during the rise of the oil and catalyst through riser 4. This conversion results in a coke lay down on the catalyst. Since the gas oil is a clean stock, it does not contain contaminating metals. Therefore, the coke lay down on the catalyst is free from contaminants, especially metals. For the last stages of its journey through riser 4, the mixture of catalyst and oil and conversion products is joined by a :residuum oil which is introduced by way of pipe 7 into riser 4. The admixturc of partially converted gas oil, catalyst and just introduced residuum now becomes a homogeneous mass of partly converted gas oil, catalyst which has been partly spent, and residuum which begins to undergo conversion. The conversion of the gas oil and residuum is continued in reactor 8. In reactor 8 upon a desired conversion accomplished by maintaining the admixture in the reactor for a desired length of time, vapors are separated and passed by way of conduit 9 into fractionator 10. From fractionator 10 there is removed overhead a stream containing gases and light hydrocarbons, including gasoline. A side stream 12 will contain a heavier fraction such as one including light and heavy cycle oils. rlfhe streams removed by way of lines 11 and 12 are elsewhere. treated as known in the art. A heavy oil condensate is collected in the bottom of tower 10 and passed by way of line 28 to settler 30, and a decanted oil product 29 is recovered. From settler 30, a slurry of heavy oil-metals containing catalyst fines is passed by way of conduit 13 to conduit 7 for admixture with the residuum, passing from oil preheater 26. Alternately, I may pass the oil-catalyst mixture in line 13 by way of line 25 and heater 26 to line 7, or split this stream in 13, part passing through heater 2.6 and part passing directly to line 7, lby-passing heater 26. Spent catalyst separated from the oil undergoing conversion in reactor 8 is passed by way of downcomer 14 .through stripper 1S wherein it is stripped with stripping steam introduced through conduit 16 and by way of conduit 19 and gate valve 18 to riser pipe 17. In riser pipe 17, the spent catalyst is transported to regenerator 20 wherein it is regenerated in the presence of air according to methods known in the art. Briey, in regenerator 20 the catalyst is raised to a temperature and maintained there for a time sufficient to burn oli coke which has been added thereto by the conversion of the gas oil and the residuum. To the extent that new catalyst is added to the system, it may not be necessary to completely burn off all of the coke which has been deposited upon the catalyst during the said conversion. During the burnoif in regenerator 20, .the coke resulting from the residuum and containing metals will be burned off and the combustion gases containing the said metals will be removed from the top of the regenerator through conduit 23 for treatment elsewhere. Through the extent that some of the combustion gases are added to the air for conrbusting the carbon from the spent catalyst and are ultimately again removed by way of conduit 23, these may be used to temper the combustion air. However, it is presently preferred to not use the said combustion gases to any substantial extent because, of course, these gases contain the metals which earlier contaminated the catalyst. One skilled in the art in possession of this disclosure will be able'to determine by mere routine tests just how much of the said combustion gases he can use advantageously and still obtain to a desired extent the advantages of the invention. Regenerated catalyst from regenerator 20 is passed by way of standpipe 5, as earlier described, into admixture with the gas oil coming from oil preheater 2. From time to time or constantly, as desired, a small portion of fresh catalyst can be passed from catalyst storage 21 and pipe 22 to regenerator 20.

From the foregoing description, it will be noted that the catalyst at all times is either fresh catalyst or regenerated spent catalyst but is always protected by a nonmetals containing coke lay down before it is contacted with the metals-containing residuum which is fed by way of pipe 7 into Iriser 4. It will also be noted that the clean charge stock is cracked in the presence of the least coke-containing catalyst and in the absence of metal contaminant. Of course, steam is preferably injected with the low carbon residue (metals-free) and the high carbon residue (metals-containing) oils prior to the contact of the oils with the cracking catalyst materials.

In the foregoing example, the `ratio of catalyst, which is a silica-alumina type cracking catalyst, to oil in riser 4 before the residuum is admixed with the gas oil catalyst mixture will be in the range of 4:1 to 8:1. Also, the temperature in the regenerator will be in the neighborhood of approximately 1020 to 1100 F. This temperature may vary somewhat outside of the range given depending upon the precise character of the catalyst which is employed, as will be understood by those skilled in the art in possession of this disclosure. The ratio of residuum to the gas oil being converted in presence of the catalyst will be in the approximate range of from about 1:10 to 4:10. The residence time in reactor 8 will be approximately 10` to approximately 30 seconds.

The gas oil which is fed to preheater 2 in my specific example will be a gas oil having a gravity of 30 API and is substantially metals-free. The residuum containing metals is an oil resulting from the distillation of a metals contaminant containing crude oil and in the example is specifically a residuum having the following characteristics and obtained from a vacuum distillation: specific gravity 60/60 F. of 0.95; Cleveland Open Cup flash of above 600 F.; Road Oil viscosity at 210 F. of above 60 seconds. The metals content (nickel, vanadium, and iron measured as oxides) is about 300 parts per million.

Reasonable variation and modification are possible Within the scope of the foregoing disclosure, drawing and the appended claims to the invention, the essence of which is that a metals-containing oil is cracked employing a catalyst which is a priori protected by a coke lay down obtained preferably by converting a cokable material with the said catalyst just before it is contacted with said metals-containing oil, substantially as set forth and described herein.

I claim:

1. In the catalytic cracking of an oil containing metals which upon contact with a catalyst deposits metal contaminants thereon resulting in an undesirable alteration of the activity and selectivity of said catalyst at least with respect to the type of reaction it will cause to occur when it has been regenerated and is again used, the improvement which comprises laying down coke upon said catalyst by contacting the same with a substantially metals-free cokable material under cracking conditions of time and temperature so as to cause immediate cracking to be initiated so as to cause a coke lay-down upon said catalyst to begin immediately, continuing said contacting until a substantial and desirable total coke laydown of about 1 percent by weight of the catalyst is obtained upon said catalyst and then contacting said metals-containing oil with said catalyst having said coke lay-down thereon under oil conversion conditions and effecting conversion of said metals-containing oil with concomitant lay down of metals and a further amount of coke on said catalyst.

2. An operation according to claim 1 wherein Said metals-containing oil is a residual oil.

3. An operation according to claim 1 wherein said metals-containing oil is a crude oil.

4. An operation as described in claim 1 wherein after the conversion of the metals-containing oil, the catalyst is separated therefrom, the catalyst is then regenerated and wherein during the regeneration the coke and metals laid down upon the catalyst are removed from the catalyst by maintaining it under regeneration conditions until substantially all of said metals and coke resulting from `the conversion of said metals-containing oil has been burned oil therefrom and then the thus regenerated catalyst is returned to a step in which it is again contacted with a metals-free cokable material under conditions to cause a further coke lay-down upon said catalyst.

5. An operation according to claim 4 wherein said cokable material is a substantially metals-free convertable oil.

6. In a fluidized catalytic conversion of a hydrocanbon oil containing metals in which metals deposited upon the catalyst cause the catalyst to function undesirably, the steps in combination as follows: admixing regenerated iluidized catalyst having about 0.3 percent by weight thereof of coke thereon with a metals-free hydrocarbon oil thus forming a mixture of fluidized catalyst and oil vapors which have been heated to a cracking temperature, conveying the said mixture to a lreaction zone and there causing conversion of the said oil vapors in said mixture until there has been deposited upon the said catalyst a lay-down of about 1 percent by weight of coke free from contaminating metals, then adding to said mixture a metals-containing convertible hydrocarbon oil, continuing the conversion of both oils in the presence of the said catalyst, separating converted oil from catalyst, regenerating the catalyst until coke resulting from the conversion ensuing upon admixture of the metals-containing oil has been substantially burned therefrom, separating combustion gases containing the metal contaminants from said catalyst and supplying said catalyst as said regenerated catalyst.

7. In a catalytic cracking of an oil containing metals which upon contact with a catalyst deposits metal contaminants thereon resulting in an undesirable alteration of the activity and selectivity of said catalyst at least with respect to the type of reaction it will cause to occur when it has been :regenerated and is again used, the improvement which comprises laying down coke upon said catalyst by contacting the same with a substantially metals-free cokable material heated to a temperature of about 750 F. so as to cause immediate cracking to be initiated so as to cause a coke lay-down upon said catalyst to begin immediately, continuing said contacting until a substantial and desirable total coke lay-down of about 1 percent by weight of the catalyst i-s obtained upon said catalyst and then contacting said metals-containing oil with said catalyst having said coke lay-down thereon under oil conversion conditions and effecting conversion of said metals-containing oil with concomitant lay down of metals and a further amount of coke on said catalyst.

References Cited in the le of this patent UNITED STATES PATENTS 2,461,958 Bonnell Feb. 15, 1949 2,651,600 Tait et al Sept. 8, 1953 2,742,405 Mattox Apr. 17, 1956 OTHER REFERENCES Wrightson: Analytical Chemistry, vol. 21, No. 12, December 1949, pages 1543 to 1545.

Claims (1)

1. IN THE CATALYTIC CRACKING OF AN OIL CONTAINING METALS WHICH UPON CONTACT WITH A CATALYST DEPOSITS METAL CONTAMINANTS THEREON RESULTING IN AN UNDESIRABLE ALTERATION OF THE ACTIVITY AND SELECTIVITY OF SAID CATALYST AT LEAST WITH RESPECT TO THE TYPE OF REACTION IT WILL CAUSE TO OCCUR WHEN IT HAS BEEN REGENERATED AND IS AGAIN USED, THE IMPROVEMENT WHICH COMPRISES LAYING DOWN COKE UPON SAID CATALYST BY CONTACTING THE SAME WITH A SUBSTANTIALLY MEALS-FREE COKABLE MATERIAL UNDER CRACKING CONDITIONS OF TIME AND TEMPERATURE SO AS TO CAUSE IMMEDIATE CRACKING TO BE INITIATED SO AS TO CAUSE A COKE LAY-DOWN UPON SAID CATALYST TO BEGIN IMMEDIATELY, CONTINUING SAID CONTACTING UNTIL A SUBSTANTIAL AND DESIRABVLE TOTAL COKE LAYDOWN OF ABOUT 1 PERCENT BY WEIGHT OF THE CATALYST IS OBTAINED UPON SAID CATALYST AND THEN CONTACTING SAID METALS-CONTAINING OIL WITH SAID CATALYST HAVING SAID COKE LAY-DOWN THEREON UNDER OIL CONVERSION CONDITIONS AND EFFECTING CONVERSION OF SAID METALS-CNTAINING OIL WITH CONCOMITANT LAY DOWN OF METALS AND A FURTHER AMOUNT OF COKE ON SAID CATALYST.

Images