US2704738A - Process for refining hydrocarbon oils - Google Patents

Description

United States Patent 1 2,704,738 PROCESS FOR REFINING HYDROCARBON OILS Warren C. Simpson, Berkeley, Calif, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application July 5, 1950, Serial No. 172,193 9 Claims. (Cl. 196-1412) This invention relates to the art of treating hydrocarbon oils. It pertains more particularly to a process for removing undesirable substances such as coke-forming constituents and other related asphaltic substances from hydrocarbon oils, especially from residual petroleum hydrocarbon oils, to prepare the same for use as catalytic cracking stock and at the same time to produce asphaltic products.

The use of residual hydrocarbon oils either alone or mixed with, for example, oil distillates, as catalytic cracking stock is attractive for economical reasons because of the large production of residual oils in the refining of petroleum oils. Solvent deasphalting of topped crude oil and of vacuum flasher bottoms with propane, butane or with any other various deasphalting agents has been considered in this connection for the utilization of these residual oils in order to obtain catalytic cracking feed stock in excess of that now obtained by, for example, vacuum flashing of topped crude oil. In catalytic cracking stock, it is advantageous to reduce the amount of coke-forming constituents therein to a minimum for a number of reasons, chief of which is that the cokeburning capacity of the catalyst regenerator is frequently the limiting factor which determines the maximum allowable throughput of a catalytic cracking unit. It is well known that the constituents of petroleum oils which form coke most readily when subjected to catalytic cracking are the aromatic constituents and particularly the aromatic constituents which contain sulfur and nitrogen atoms.

It is a principal object, therefore, of this invention to provide a useful process for treating hydrocarbon oils, particularly residual hydrocarbon oils. A further object is to provide a process whereby coke-forming constituents are economically removed from petroleum oils. Another object is to provide a method for readily, economically and elfectively removing coke-forming constituents and other related asphaltic substances from heavier hydrocarbon oils, such as residual hydrocarbon oils. A concomitant object is to produce an improved asphaltic composition. These objects will be more clearly understood and other objects will be evident from the detailed description of the invention.

Now, in accordance with the present invention, it has been found that the above and other objects are realized by a process wherein a hydrocarbon oil which contains undesirable impurities such as coke-forming constituents and/or other related asphaltic substances is treated with an amount of precipitating agent, preferably water-soluble, for said impurities, followed by separation of the resulting precipitated matter. This treatment may be and preferably-is, combined with other concurrent and/or subsequent treatments to provide I advantageous com- 7 bination treatments or processes and wherein the abovedescribed treatment is in the nature of a pretreatment.

Generally described, the present invention provides a process for treating a hydrocarbon oil, including shale oil and particularly residual petroleum oil, which contains undesirable coke-forming constituents and/ or other related asphaltic constituents, which process comprises contacting said oil with a 11111101 amount of one or more of a precipitating agent, preferably water-soluble, selected from the group of chemical compounds containing at 2,704,738 Patented Mar. 22, 1955 ploy aqueous acidic (i. e., containing free acid, such as a mineral acid, viz. hydrochloric, nitric, phosphoric, sulfuric, etc.) solutions of the above compounds or the acidic salts of the above compounds as the precipitating agent.

With the application of the above treatment to asphalt containing residual petroleum hydrocarbon oil, the separated oil fraction after removal of the precipitated cokeforming constituents according to the invention may be advantageously further treated as by a deasphalting process employing propane, butane, or any other suitable deasphalting agent to produce a suitable catalytic cracking stock. In accordance with a preferred embodiment of the invention, the precipitation of the coke-forming impurities by employing the above-described agents is combined with the deasphalting process in a single operation with the attendant advantage that only one separation step is required since the precipitated coke-forming constituents separate out with the asphalt or propane insoluble phase.

In general, the inorganic compounds of the aforesaid metals, preferably the salts of the various inorganic min-. eral acids, are suitable, especially those salts and/ or compounds wherein the metal represents the positive or cationic part of the salt. Suitable representative metal salts are the halides, such as ferric chloride, ferrous chloride, ferric bromide, nickel chloride, chromic chloride, cobalt chloride, manganese chloride; the acetates such as nickel acetate; the nitrates such as ferric nitrate, chromic nitrate, nickel nitrate and manganous nitrate; the sulfates such as ferrous sulfate, ferric sulfate, nickel sulfate, chromic sulfate, manganic sulfate and manganous sulfate, or mixtures of salts of the aforesaid elements; or aqueous solutions thereof. Steel mill pickel liquor, the average composition of which is approximately, in per cent by weight, 5% H2804, 15% FeSO4 and 80% H2O is also useful as the precipitating agent. The principal coke-forming-constituent precipitating agent therein being ferrous sulfate.

The quantity by weight in which the precipitating agents of the invention are added to the hydrocarbon oil depends upon the quantity of the coke-forming constituents and other related asphaltic material therein. In general, a minor amount, usually an amount not more than 10% by weight of the oil to be thus treated, and in most cases not more than 5% and usually about 1%, by weight of the oil, effects suflicient precipitation of the coke-forming impurities and treatment of the oil.

The precipitation treatment of the coke-forming constituents and other related asphaltic substances is not confined to any particular temperature or temperature range. The precipitation treatment is suitably carried out at normal or elevated temperatures. When applying normal or slightly elevated temperatures the precipitated, coke-forming constituents may not settle out readily, particularly if the treated hydrocarbon oil is a heavy viscous residual oil. This difficulty may, however, be overcome by increasing the temperature or by the addition of diluents or solvents to thin out the viscous oil or by centrifugation or by any other suitable method. When,

however, the precipitation of the coke-forming consti-" tuents of a hydrocarbon oil, such as a residual oil, is carried out immediately prior to or concurrently with a deasphalting step, such as by propane deasphalting, this difliculty is ordinarily not present since, due to fluidity of such a hydrocarbon mixture, the precipitated cokeforming constituents along with the precipitated asphalt readily separate out.

After the removal of the precipitated coke-forming constituents together with the precipitating agent therefor, said agent may be recovered therefrom if desired, by suitable chemical and/ or solvent or separation treatment. For example, if ferric chloride is employed as the precipitating agent, the iron salt may be removed and recovered from the precipitate by heating the precipitate with water and an oil solvent, such as benzene, to hydrolyze the iron salt and to precipitate hydrous ferric oxide. It is preferred however to treat the separated precipitated matter with water at relatively low temperature, usually about 20 C., to leach out and dissolve the precipitating agent therein. This is advantageous since it permits the recovery of the precipitating agent, e. g.

' tated out.

, ferric chloride, unchanged. If however, the precipitation of coke-forming constituents in a petroleum residual oil is accompanied byor subsequently followed by a de-- asphalting operation, it may be preferable to separate the precipitated coke-forming constituents and asphalt together since the precipitating .agentgpa-rticularly ferric chloride, functions as a blowing oxidation catalyst, inthe preparation of air-blown asphalts, thereby obviating the necessity of adding a blowing catalyst to the recovered, asphalt. It appears that the incorporation of the ferric chloride or other agent in the asphalt simultaneously with the separation (deasphalting) of the asphalt from the other oil constituents results in a more. uniform incorporation of the agent in the asphalt and hence a more effective air-blowing operation.

The following examples representing the practice of thepresent invention as applied to thetreatment of exemplary materials illustrate the invention and set forth the advantages to be obtained by practicing the invention, but they are not to beconstrued as limitative thereof.

EXAMPLEI An isopentane solution of the isopentane soluble portion of a distillation residue of a Santa Maria crude was shaken with a minor amount of a saturated aqueous solution of ferric chloride at room temperature with the result that heavy, easily removed insoluble complexes precipi- Examination of these complexes showed that the hydrocarbon portion thereof contained high percentages of sulfur and of nitrogen, greater than the percentages of sulfur and of nitrogen of the hydrocarbons remaining dissolved in the isopentane solution. It was also foundthat the amount of complex formed could be controlled up to a certain limit by the amount of saturated aqueous ferric chloride solution added. Another experiment'was performed using steel mill pickle liquor containing ferrous sulfate as the precipitating material and similar results were also obtained.

EXAMPLE II To demonstrate that a ferric chloride treatment precipitates coke-forming constituents such as nitrogen and sulfur-containing constituents of an aromatic character, from residual hydrocarbon oils, 2. topped Wilmington crude (long residue) was propane deasphalted after being subjected to a ferric chloride treatment in accordance with the invention. The topped crude was heated to about 212 F. and about 1% by weight, of said crude, of anhydrous ferric chloride was added thereto with stirring and the mixture was held at 212 F. for about minutes after which it was cooled to about 150 F. in a propane deasphalting apparatus, wherein it was intimately contacted withpropane in a volume ratio of propane to topped crude of 4 to l, at atemperature of about 150 F. Mixing and settling times of 30 minutes and, one hour, respectively, were used, the precipitated material and asphalt being separated from the propane solution of oil. For purposes of comparison another sample of the same topped Wilmington crude was propane deasphalted under the same conditions but without any ferricchloride treatment. The properties of the products as a resultof the above treatments are given in Table I below:

Table I "USE OF FERRIC CHLORIDE INDEASPHALTING PROCESS PRODUCTION OF CATALYTIC CRACKING STOCK FROM A WILMINGTON TOPPED CRUDE (LONG RESIDUE) of the oil produced by propane deasphalting alone.

4 Although the data presented in Table I indicate that the ferric chloride treatment caused a very slight drop in the yield of deasphalted oilpthe reproducibility of the oil yield values is probably not much better than the indicated difference. The analyses of the oils obtained show that in the case of the ferric chloride treatment an oil of high A. P. I. gravity is produced and that this oil has a Conradson carbon residue of only about /3 %';it e Conradson carbon residue is an indication of the coke forming tendencies of oil when used as catalytic cracking stock. lso the sulfur and nitrogen contents of the ferric chloride treated oil are lower than for the untreated oil. The extent of lowering of the sulfur and nitrogen contentsof ferric chloride treated oil can be controlled by varying the amount of ferric chloride used. Y

The ferric chloride treatment produced an oil with a lower refractive index and a lower specific dispersion which indicate a lower: aromatic hydrocarbon content therein. The bromine number of the ferric chloride treated oil is. also lower, indicating a reduced amount of unsaturated hydrocarbon material therein. It is also pointed out that the iron content of the/treated and untreated oils. is low in both cases and amounts to onlya few thousandths of a per cent, thus clearly showing that the added ferric chloride and the complexes it forms with the coke-forming impurities. are thrown into the asphalt or propane insoluble phase in the deasphalting operation. a The properties of the asphalts obtainedare also given in- Table I. The data demonstrate that ferric chloride treatment yields asphalt. of lower penetration index than is obtained by propane deasphalting alone. The asphalt was particularly suitable as a blowing flux. v

In view of its higher A. P. I. gravity, lower Conradsoncarbon residue, lower sulfur and nitrogen content, lower aromatic content and lower bromine number, the ferric chloride treated and propane deasphalted oil is a better and more desirable catalytic cracking stock than oil obtained by propane deasphalting alone; This was demonstrated by comparative tests wherein these oils were sub jected to catalytic cracking. The operating conditions of the catalytic cracking and the distribution of the prod ucts obtained are set forth in Table II below: a

Table 11 7 CATALYTIC CRACENG OF OILS FROM A WILMINGTON LONG RESIDUE-INFLUENCE OF FERRIC CHLORIDE ON PROPANE DEASPHALTLNG OPERATION Temperature, 500 0.

Process period, 10 minutes.

Two cycles.

Catalyst Surface Area about 75 mF/g.

[Volume ratio, propane/0il.=4/L Temnerature, 150 F] Propane Propane De Wilmington asphalted F P3- Topped Wilmington Crude Topped 5%;

Crude Crude 'W. Percent Oil Yield I00 71. 5 69. 0 API Gravity 17.1 19. 5 20. 6 Percent Carbon Residue (Con- 9.09 3. 04 2. 01

radson). Percent C 85.88 85. 57 85. 52 PercentH. 11.51 12. 11 1226 Percent N. 0.67 0.40 0.30 Percent S.-... 1.79 1. 55 1. 49 Molecular Weight. 426 366 358 'Refractive Index Too Dark 1. 5139 1. 5096 Specific Disperslondo 141 130 Bromine Number. 18. 16. 9 Percent Fe 0.011(5) 0. 00(1) 0. 00(3) Properties of Asphalt:

Penetration at 77 F. 20 ,10 Softening Point, F. 136 173.5 Penetration Index 1. 3 +0. 9

1% FeO]; based on topped crude, 10 minutes at 212 F.

Catalytic cracking data. for a vacuum flashed distillate from the same topped crude which is a normal feedstock for the catalytic cracking operation are also given for purposes. of comparison. The suitability of the various oils tested as catalytic cracking feedstock can be deter.- mined by comparing the product distribution of each since they have all been cracked to 50% conversion. The data of Table II clearly demonstrate that the oilobtained by ferric chloride treatment and propane deasphaltingis superior as a catalytic cracking stock .to the oil obtained by propane deasphalting alone, since the ferric chloride treated oil produced more gasoline, more gas (including C and substantially less coke. In fact, the ferric chloride treated oil produced less coke on apercentagejhasis than did the vacuum flashed distillate which represents only 55'% of the long residue. Thus,,the1ability offer-tic chloride to remove coke-forming constituents from cat'a lyt1c cracking stocks is thereby demonstrated.

2,704.,rss

To demonstrate that ferric chloride treatment may also be used to produce suitable catalytic cracking feed stock from short residues (vacuum flasher bottoms) the following experiments were performed.

Vacuum flasher bottoms were heated to about 212 F. and 1% by weight of said bottoms of anhydrous ferric chloride was added with agitation. The mixture was then heated to about 390 F. and held at this temperature for a period of about 30 minutes with frequent agitation. It is considered that the reactions between farric chloride and the various coke-forming constituents and related asphatic material of the flasher bottoms are hastened with an increase in temperature. Thereupon the ferric chloride treated flasher bottoms were cooled to about 100 F. and deasphalted with 10 volumes of propane per volume of flasher bottoms. A single stage batch extraction was carried out in a horizontal rotary mixer with a mixing time of about 30 minutes and a settling time of about one hour. The above-indicated mixing and settling time are not critical however, and may be greatly varied depending upon operating conditions, equipment, ferric chloride concentration, etc. Another portion of the same vacuum flasher bottoms (pitch) was propane deasphalted under similar conditions but without the ferric chloride treatment. The yield data and the properties of the oil produced by these methods from the flasher bottoms are presented in Table III together with an analysis and properties of the vacuum flasher bottoms for the purpose of comparison.

Table III USE OF FERRIC CHLORIDE IN DEASPHALTING PROCESS PRODUCTION OF CATALYTIC CRACKING STOCK FROM A WILMINGTONFLASHER PITCH (SHORT RESIDUE) [Volume ratio, propanelPitch=10/1. Temperature, 100 F.]

Pgipane BPrgrlianDeease a e gfi gi phalted asphalted Pitch Wilmington Wilmington Flasher Flasher Pitch Pitch W, Percent Oil Yield 100 38. 37.8

API Gravity 7.8 18. 2 19. 7

Percent Carbon Residue (Con- 3. 48 2. 50

radson).

Percent C 85.40 85. 83 85.68

Percent H. 10. 42 12. 07 12.03

Percent N- 1. 21 0. 35 0. 33

Percent S 2. 30 1. 72 1. 63

Molecular W gh 2 569 535 Refractive Index- Too Dark. 1. 5255 1. 5206 Specific Dispersion o- 143 Bromine Number- 19. 3 17. 4

Percent Fe 0. 000(4) These experiments demonstrated (as the data presented in Table 111 show) that a ferric chloride treatment is especially useful in the preparation of catalytic cracking feed stock from residual oils. While the amount of oil recovered was only very slightly reduced by the ferric chloride treatment, the oil obtained by ferric chloride treatment had a higher A. P. I. gravity value and a considerably lower Conradson carbon residue indicating thereby that at least a portion of the coke-forming constituents had been removed. The ferric chloride treated oil also had lower sulfuric and nitrogen contents as well as a lower molecular weight. In addition the refractive index and the specific dispersion of the ferric chloride treated oil was lower, indicating a reduced aromatic content and therefore less refractory composition as compared with the oil prepared by propane deasphalting alone. A lower content of unsaturated material in the ferric chloride treated oil is indicated by the lower bromine number. Furthermore, the iron content of the ferric chloride treated oil is extremely low, indicating that the ferric chloride and the coke-forming constituents and related asphaltic materials with which is forms complexes are thrown into the asphalt or propane insoluble phase during the propane deasphaltmg step.

In view of the above results and observations it 1s considered that ferric chloride treated and propane deasphalted residual oil give a superior catalytic cracking feed stock over a similar oil obtained by propane deasphalting alone. Accordingly in order to demonstrate the above, these oils were subjected to catalytic cracking.

A vacuum flashed distillate of similar stock was also subjected to catalytic cracking for the purpose of comparison. The operating conditions of the catalytic cracking and the distribution of the products obtained are set forth in Table IV below:

Table IV CATALYTIC CRACKING OF OILS FROM A WILIVIINGTON FLASHER PITCH INFLUENCE OF FERRIC CHLORIDE ON PROPANE DEASPHALTING OPERATION Temperature 500 C.

Process period, 10 minutes.

Two cycles.

Catalyst Surface Area about 75 mfl/g.

Propane Propane- Vacuum eas- FeCh De- Flashed phalted asphalted Distillate Flasher Flasher (55% of Pitch Pitch Long (38% of (37.8% of Residue) Flasher Flasher Pitch) Pitch) W. Percent Reacted 55. 0 55.0 55. 0 W. Percent Gasoline (Gs-205 C. B. P. 27.9 29.7 30.3 Vvg. gercent: (($oke( (5 all h 9. 1 10.3 8.3 ercen as 4 an g ter).. 18.0 15.1 16.8

W. Percent Gas Oil (over 205 C.

The suitability of the various oils as catalytic crackmg feed stock can be determined by comparing the product d1str1but1on of each since the three oils tested were each cracked to 55% conversion. The data of Table IV clearly demonstrate that the oil obtained by ferric chloride treatment and propane deasphalting is superior as a catalytic cracking stock to the oil obtained by propane deasphalting alone. The ferric chloride treated oil produced more gasoline, more gas (including C4) and considerably less coke. Indeed, the ferric chloride treated oil produced more gasoline and less coke than the vacuum flashed distillate which is the normal catalytic cracking feed stock.

EXAMPLE IV An isopentane solution of shale oil, prepared by dissolving 25 parts by weight retorted (N. T. U.) shale oil m parts by weight isopentane was shaken with about 200 parts by weight saturated aqueous solution of ferric chloride at room temperature with the result that heavy, readilyfilterable, insoluble complexes precipitated. EX- amination of these complexes showed that the hydrocarbon portion thereof contained relatively high percentages of sulfur and nitrogen and that the hydrocarbon portlon thereof amounted to about 55% by weight of the original shale oil sample. Furthermore an analysis, the results of which are set forth in Table V below, of the untreated and treated shale oil showed a substantial reduction n sulfur and nitrogen content of the treated shale o1l (1. e. that portion which did not form a ferric chlor1de complex).

Table V FeCIs N. T. U. Treated Percent weight Retorted N. T. U. Shale Oil Retorted Shale Oil 84. 4 85. 10 ll. 6 13. 17 f 0. 13

. 0. Oxygen (by dificrence) 1. 38 1. 8

EXAMPLE V I To further demonstrate the invention, numerous solutrons of a residual hydrocarbon oil, prepared by dissolving 25 parts by weight oil in about 45 parts by weight isopentane, were contacted at room temperature with 50 parts by weight saturated aqueous solution of various salts according to the invention. In all instances, heavy, filterable, insoluble complexes were formed. Examination of these complexes disclosed that the hydrocarbon portion thereof contained relatively high percentages of sulfur and nitrogen, higher than the percentages of these elements 1n the original sample. Furthermore, analysis 7 7 of the untreated treated {oil showed a reduction in sulfur and nitrogen content of the-treated oil (i. -50. that portion whichdid not .form a complex). :Listed *below in Table VI are various inorganic metal salts according to the invention which formed complexes; also is listed that portion of the oil withw' hich complexes were formed.

Table VI Percent weight oil which formed complexes Nickel chloride 3.52

Nickel sulf I 9.0

' A feature of the subject invention relates to the production of air blown asphalts. It is known that oxidation catalysts, for example, ferric chloride, act as catalysts in the airblowing 'of'asphalt. Actual tests have shown that ferric chloride added to ares'idual oil a before or during a dea'sphalting operation, for example,

a propane or butane, etc., deasphalting PI'OCBSSiIrfiC- cordance with the invention .is as eifective a catalyst as when added during blowing flux formulation. Thus, it is possible to make double use of the coke-forming constituents precipitating agents. For example, ferric chloride treatment may not only be employed as a method of producing more suitable catalytic cracking stocks from residual oils but alsojto produce a's'phalts therefrom-which blow to desired penetration and softening point more rapidly than ordinary jblowing fluxes.

I claim as my invention:

1. A rneth'od of producing a suitable catalytic cracking feed stock from an asp'haltic residual petroleum oil which also contains constituents which p'rorrrote cokeformation in catalytic cracking operation which process comprises contacting said 'oil sin't'ultaneously with a saturated hydrocarbon of from 3 to 5 carbon atoms as deasphalting agent and with a minor amount of from about 1% to about by weight ,ofthe oil of a water-soluble inorganic salt containing ,as cationic portion at least one fof'the vartabl'e yalenc'e'elements having an atomic number o f' from 24 1028, inclusive, as'essentially the only chemically "reactive precipitating agent for said coke-forming constituents, whereby a phase comprising a solution "of oil in sa'iddeasphalting agent and a phase comprisingthe resulting precipitate and asphalt are formed, and separating thez're'sulting precipitate and asphalt from the solution "of 'oil in the deasphaltin'g agent.

2. A methodaccording to claim 1, wherein the hydrocarbon dea's'phalting agent is essentially propane. I

3. A'method according to claim 2, wherein the inorganic salt is a halide.

A method according to claim 2, wherein the inorganic salt is a chloride. s 5. A method according to claim 2, wherein the organic salt "is ferric chloride.

6. A method "according to claim 1, wherein their!- organic salt is ferrous sulfate provided as steel mill pickle liquor.

7. A method acc'ordingfto claim '1, wherein the inorganic salt is =chromicchloride.

8. A method according 'to claim 1, wherein the inorganic's'alt is manganese chloride.

'9. A method according-to claim '1, wherein the in organic salt is nickel sulfate.

References Cited the tile of this patent 'UNITED STATES PATENTS 655,500 MacAlpine Aug. 7, 1900 1,545,440 Neuman July 7, 1925 1,601,406 Moody Sept. 28, 1926 1,703,158 McClave Feb. 26,1929 1,799,780 Caplan Apr. 7, 1931 1,822,842 Caplan Sept. .8, 1931 1,970,283 Day- Aug. 14, 1934 1,988,711 Bray et al. Jan. 22, 1935 2,002,250 Payne et al May 21, 1935 2,010,606 .Moser Aug. 6, 1935 2,013,399 Benedict et a1. Sept. 3, 1935 2,096,163 Day Oct. 19, 1937 2,367,385 Weeks et a1. Jan 16, 1945

Claims (1)

1. A METHOD OF PRODUCING A SUITABLE CATALYTIC CRACKING FEED STOCK FROM AN ASPHALTIC RESIDUAL PETROLEUM OIL WHICH ALSO CONTAINS CONSTITUENTS WHICH PROMOTE COKEFORMATION IN CATALYTIC CRACKING OPERATION WHICH PROCESS COMPRISES CONTACTING SAID OIL SIMULTANEOUSLY WITH A SATURATED HYDROCARBON OF FROM 3 TO 5 CARBON ATOMS AS DEASPHALTING AGENT AND WITH A MINOR AMOUNT OF FROM ABOUT 1% TO ABOUT 10% BY WEIGHT OF THE OIL OF A WATER-SOLUBLE INORGANIC SALT CONTAINING AS CATIONIC PORTION AT LEAST ONE OF THE VARIABLE-VALENCE ELEMENTS HAVING AN ATOMIC NUMBER OF FROM 24 TO 28, INCLUSIVE, AS ESSENTIALLY THE ONLY CHEMICALLY REACTIVE PRECIPITATING AGENT FOR SAID COKE-FORMING CONSTITUENTS, WHEREBY A PHASE COMPRISING A SOLUTION OF OIL IN SAID DEASPHALTING AGENT AND A PHASE COMPRISING THE RESULTING PRECIPITATE AND ASPHALT ARE FORMED, AN SEPARATING THE RESULTING PRECIPITATE AND ASPHALT FROM THE SOLUTION OF OIL IN THE DEASPHALTING AGENT.