US2915460A

US2915460A - Refining mineral oil

Info

Publication number: US2915460A
Application number: US478768A
Authority: US
Inventors: Ivor W Mills; Peter B Murray
Original assignee: Sun Oil Co
Current assignee: Sunoco Inc
Priority date: 1954-12-30
Filing date: 1954-12-30
Publication date: 1959-12-01
Anticipated expiration: 1976-12-01

Description

Dec. 1, 1959 l. w. MILLS ETAL 2,915,460

REFINING MINERAL OIL Filed Dec. 30, 1954 O Bauxite Containing I Iron Compound l0 Sour Gasoline Aqueous NHOH Ammonia Treatment I I2 Sweetening Drying J Sweetened Gasoline Bauxite 2o Magnetic Separation Sour Gasoline 2| 23 Aqueous NGOH Caustic Treatment sweetening Water Wash 22 Drying Sweetened Gasoline INVENTORS. IVOR W. MILLS BY PETER B. MURRAY Wkzb $(wli1 ATTOR NE Y United States Patent 2,915,460 REFINING MiNERAL OIL Ivor W. Mills, Glenolden, and Peter B. Murray, Media, Pa., assignors to Sun Oil Company, Philadelphia, Pa., a

corporation of New Jersey 1 Application December 30, 1954, Serial No. 478,768 Claims; (Cl. 208-489) This invention mates; to the refining of mineral oil and more particularly to the conversion or removal of mercaptans and other objectionable sulfur compounds from mineral oil.

Various means have been proposed for converting or removing mercaptans from various mineral oilfractions such as gasoline, naphtha, etc., and some of the means which have been proposed may produce a product hav ity, the mineral oil products obtainedsubsequently from that bauxite will contain unsatisfactorily large amounts of mercaptans.

According to the invention, a process for reduction of mercaptan content, employing an adsorbent, is provided wherein the life of the adsorbent is substantially increased. This makes it possibleto treat mineral oil, for substantially longer periods before having to regenerate or discard the adsorbent.

The process of the invention is applicable to those adsorbents which contain' iron or iron compounds. The process of the invention involves the treatment of the adsorbent with an alkali prior to the use of the adsorbent as a-sweetening agent for mineral oili Alkalis, for the purpose of the present invention, are considered to include ammonia,- ammonium hydroxide, ammonium carbonate, and'the alkali metal hydroxides and carbonates, e.g. sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, etc. Generally; aqueous solutions of alkalis will be employed in treating adsorbents according to the invention, but gaseous ammonia can also be employed.

It has been found'that treatment of adsorbents, with alkalis as subsequently more fully described, considerably increases the-ability of the adsorbent to reduce the mercaptan content of hydrocarbon materials.

The invention will be further described with reference to the attached drawings. Figure 1 is aschematic flow sheet of one embodiment of the proce'ssaccording to the invention. Figure 2 is a schematic flow sheet of another embodiment.

Referring to Figure 1, bauxite containing iron compounds is introduced into ammonia treating zone 10. The bauxite which is introduced may be a bauxite which has not been givenany prior treatment other than the customary thermal= activation, eg at a temperature of 600700 F. or higher, and which contains substantial amounts of iron oxide, generally within the range from 1 ton25 percent,.for exampleabout 15 percent; other iron compounds may also'be present. Alternatively'the V 2 bauxite introduced into zone 10 may have been treated in any known manner to reduce the iron content. It is to be noted however that preferably the iron content of the bauxite employed is high, and therefore it is not preferred to use a bauxite which has been treated for reduction of iron content.

The bauxite introduced in zone 10 may have been treated beforehand to increase the iron content, for example by contacting the bauxite with an aqueous solution of an iron salt, eg ferrous or ferric chloride, sulfate, acetate, etc., preferably though not necessarily having at least 10 weight percent concentration, followed by evaporation of water from the impregnated bauxite.

Aqueous ammonium hydroxide is introduced into zone 10 and is contacted therein-with the bauxite. The contacting may be accomplished forexample by percolating an aqueous solution of ammonium hydroxide through a stationary bed of'granular bauxite. The bauxite is subsequently dried in any suitable manner, as indicated by the drying zone 11. In practice it is not necessary .to transfer the bauxite from one zone to another as indicated in the drawing. Instead-a stationary bed of bauxite which has been treated with ammonium hydroxide may be subsequently dried by blowing heated gases, e.g. air, through the bed of bauxite.

In the drying operation excess water is removed from the bauxite, and also excess ammonia is removed. It is not essential to this embodiment of the process of the invention that ammonia be present during the sweetening operation. It appears rather that-the ammonia merely has the efiect of converting the ironin the adsorbent to a different and superior form.

The conditions employed in the drying operation generally involve the use of a temperature within the approximate range from 150 F. to 600 F., preferably 200 F. to 400 F, for a suflicient period of time to obtain equilibrium at the temperature employed; the temperature employed should be above the boiling point of water at the pressure employed. The drying can for example be performed at atmospheric pressure or under vacuum conditions, e.g. at an absolute pressure less than about mm. Hg. The water removed by such drying is mainly or entirely of the type generally known as free moisture, rather than. the combined water which may be removed upon ignition of the bauxite.

Sour gasoline containing mercaptans or other objectionable sulfur compounds is sweetened by contact With' the bauxite which has been treated with ammonia and dried; the sweetening operation is indicated at zone 12. Here again it is not necessary to transfer the bauxite from one zone to another; instead the gasoline can be percolated through the same stationary bed of bauxite, after the termination of the drying operation.

Preferred conditions for the sweetening operation involve the use of atmospheric temperature and pressure. Elevated temperatures can be employed if desired, for example up to 250 F. However such elevated temperatures are notnecessary for etficient reduction of mercaptan content, and may have an adverse effect upon the gum rating of the product obtained in the sweetening operation, particularly in the case of a cracked charge stock.

It is believed that the process of the invention involves not merely physical adsorption of constituents of the charge on the adsorbent, but an oxidation of mercaptan constituents, and that the presence of oxygen is therefore required during the contact of adsorbent with hydrocarbon: material. Frequently the latter will contain suflieient oxygen, in the form of aim-without employing any additional oxygen. If additional oxygen is needed, it

I may be added to the hydrocarbon material prior to the alumina in the bauxite. contact between caustic and bauxite is less than about one adsorbent treatment, or introduced directly into the treating zone.

The sweetened gasoline product removed from zone 12 has a considerablylower mercaptan content than the original sour gasoline.- It has been found'for example that a doctor sweet product or a product having mercaptan content of as measured by the amount of a standard aqueous solution containing copper ions which reacts with the gasoline product, can be obtained.

In place of ammonium hydroxide, gaseous ammonia can be used in the treatment of the adsorbent prior to its use in sweetening.

- -Referring to Figure 2, thermally activated granular bauxite containing for example about 15 weight percent of. iron compounds as R 0, is introduced into a magnetic separation zone 20 wherein a process, as well known inthe art, for magnetically separating bauxite particles having high-iron content from bauxite particles having .lower iron content is performed. The high iron bauxite,

containing for example about 50 weight percent of iron compounds as Fe 0 is introduced into caustic treatment zone 21 wherein the bauxite is contacted with caustic soda under conditions producing a substantial improvement in the sweetening ability of the high iron bauxite without destroying the essential granular structure or mechanical strength of the bauxite. In the light ,of thev present specification, such conditions can readily be chosen by a person skilled in the art. The strength and. amount of caustic employed and the temperature .and time of the treatment are factors for which, because of their interdependence, absolute limits cannot be set. Preferably, the amount of caustic used is less than the 'stoichiometric amount for reaction with the alumina of .the bauxite; more preferably, the amount of caustic employed is about 0.5 to 2 moles of caustic per mole of Also, preferably, the time of hour.

Following the caustic treatment, the excess sodium hydroxide is removed from the bauxite, e.g. by washing with water until the pH of the eflluent wash water is mg with 20 cc. of distilled water, and then with a 28% (as NH solution of ammonium hydroxide in water until the efiluent liquid was free of precipitate, and removing eXcess water by heating at 250-400 F. and 1 mm. Hg for 3 hours. In run No. 6, the treating agent had been prepared by gently boiling for about 15 minutes a mixture of 130 cc. of a magnetically separated high iron bauxite containing of iron compounds as Fe O with 10 grams of sodium hydroxide and 200 cc. of water, washing the bauxite with water until the pH of the efiluent was about 7, and heating at 300-400 F. and 1 mm. Hg for 3 hours.

Run No. 1 is a comparison run for run No. 2, the ammonia treatment having been omitted and the bauxite heated at 300400 F. and 1 mm. Hg. Run No. 3 is a. comparison run for run No. 4, the ammonia, ferric chloride, and ammonium hydroxide treatment having been omitted and the bauxite heated at BOO-400 F. and 1 mm. Hg. Run No. 5 is a comparison run for run No. 6, the sodium hydroxide treatment having been omitted and the bauxite bed were collected, the usual size of sample being 4000 cc. In each run, the amount of bauxite in the bed 'was cc. or 64 cc. 'The various efilue'nt samples were tested for mercaptan content by titrating with a standard aqueous solution containing copper ions. In each run, the amount of effluent collected before the percent mercaptan sulfur of the'efiluent substantially exceeded 0.0001 percent, was determined. This amount indicated the capacity of the bauxite for producing gasoline having mercaptan content not exceeding 0.0001 percent. The following table shows the results obtained:

Run N0. Gasoline Initial RSH, Bauxite Capacity,

Percent 1 cc.

Straight run, undried--- 0. 0034 Ordinary, untreated; 8,000 do 0. 0030 Ordinary, NH; treated. 16, 000 Straight run, dried 0. 0027 Ordinary, untreated 28,000 0. 0020-0. 0035 Ordinary, Fe and N H; treated 64, 000 Thermal, undried 0. 0012 High iron, untreated- 16,000 do '0. 0007-0. 0010 High iron, NaOH, treated 44, 000

less than 8 and preferably about 7. Excess water is then removed, in zone 22 asindicated in Figure 2. The

Example I A series of runs was carried out wherein sour gasolines were sweetened by percolation in liquid phase at room 5 temperature through beds of bauxite. In run No. 2, the bauxite treating agent had been prepared by saturating a .fresh commercial granular ignited bauxite (containing about 15% iron compounds as Fe O with gaseous ammonia and removing excess ammonia by heating the .bauxite at 250-450 F. under an absolute pressure of about 1 mm. Hg for two hours. In run No. 4, the treatingagent had been prepared according to the procedure of run No. 2 followed by saturating the. bauxite with The superiority of run 3 to run 1 is probably attributable to the drying of the charge gasoline. In run No. 6, the mercaptan content of the 'gasoline charge was about 0.0010% for the first 20,000 cc. charged, about 0.0009% for the next 12,000 cc., and about 0.0007 for the next 12,000 cc. The superiority of run 6 to run 5 is clear, in spite of the somewhat lower initial mercaptan content in run 6. v

In runs 1, .2, 3 and 6, the space rate was about 5 volumes of gasoline. per volume of bauxite per hour throughout the run. In run 5, the space rate was 8 for 5 the first 4000 cc. charged and 5.5 for the next 12,000 cc.

charged. In run 4, thespace rate was 9 for the first 52,000cc. charged and 5 for the next 12,000 cc. charged. The mercaptan content of the efiluent rose gradually to 0.0006% during the use of the 9 space rate and then dropped to an amount equal to or less than 0.000l% when the space rate was reduced to 5. When the run was'terminated at 64,000 cc. of efiiuent, the mercaptan content of the lastkeflluent sample did not exceed 0.0001%. .This indicates that at space rate of 5, the

an about 60% solution of ferric chloride in water, wash- 75. bauxite of run 4 would have had a capacity of at least 64,000 cc., and therefore the figure of 64,000 cc. is reported in the table.

This example shows. that. ammonia or sodium hydroxide treatment of fresh bauxite containing iron compounds increases 'the ability of the bauxite to reducethe mercaptan content of straight-- run or thermal gasoline. Other experiments haveshown that alkali-treated bauxite is also effective in reducing the mercaptan content of catalytically cracked gasoline. Thus, in a run (No. '7) generally similar to run- 6 but employing'catalytic gasoline as'charge and a more severe alkali treatment (SO' grams of sodium hydroxide-and 150- cc. of water per 130 cc. of bauxite), a capacity of 24,000'cc. at space rate of was obtained.

Example-II After 72,100 cc. of thermal gasoline had been percolated through the bauxite in run 6 of Example I, the mercaptan content of the efliuent having risen to 0.0003- 0.0004% by that time, the flow of gasoline was ceased, and steam was passed through the bauxite bed for 7 hours. The bauxite was then heated at 400-500 F. and 1 mm. Hg for 3 hours, followed by wetting with naphtha. Then the flow of thermal gasoline, this time having initial mercaptan content of 0.0011%, was resumed at space rate of 5. The space rate was lowered to 3 after 32,000 cc. of effluent had been collected. The capacity of the steam-regenerated bauxite was found to be 36,000 cc., i.e. that much of efiiuent was collected before the cercaptan content of the efl iuent substantially exceeded 0.0001 percent.

This example shows that a caustic-treated high iron bauxite (60 cc.) having 44,000 cc. capacity for thermal gasoline at space rate 5 can be regenerated with steam to produce a regenerated bauxite having 36,000 cc. capacity for thermal gasoline at an average space rate of approximately 5.

Example III After 32,100 cc. of catalytic 'gasoline had been percolated through the bauxite in run 7 of Example I, the mercaptan content of the effluent having risen to 0.0003% by that time, the flow of gasoline was ceased, and steam was passed through the bauxite bed for one hour. Then 200 cc. of 10% caustic soda were percolated through the bed at room temperature. Following this, the bed was filled with 10% caustic soda and heated at steam temperature for one hour. Then the bed was drained and water washed at steam temperature until the pH of the efiiuent water was about 7. The bauxite was then heated at 460 F. and 1 mm. Hg for 3 hours. The flow of catalytic gasoline, now having initial mercaptan content of 0.0009-0.0010% was resumed. The capacity of the caustic-regenerated bauxite was found to be 12,000 cc.

This example shows that a caustic-treated high iron bauxite (60 cc.) having 24,000 cc. capacity for catalytic gasoline at space rate 5 can be regenerated with caustic to produce a regenerated bauxite having 12,000 cc. capacity for catalytic gasoline at space rate 5.

Bauxite is a preferred adsorbent for use according to the invention, but other adsorbents can also be suitably employed. Any of the well-known adsorbents for treatment of mineral oil fractions can be employed, e.g. fullers earth, silica gel, Attapulgus clay, Filtrol clay, infusorial earth, etc. If the adsorbent employed does not initially contain substantial amounts of iron, for example 1% or more, iron should be added to the adsorbent prior to the ammonium treatment according to the invention. A particularly advantageous adsorbent is a magnetically separated bauxite containing about 10 to 70 weight percent, more preferably 30 to 60 weight percent, of iron compounds as Fe O An adsorbent which is used according to the invention can be one which has been ignited or calcined prior to treatment with an alkali, or one which has not been ignited or calcined.

Temperatures ordinarily employed in igniting or calcining are those in the approximate range from 600 F. to 1400" F. 1 p

The process of. the invention is particularly advan tageously applied togasoline fractionscontaining' mercaptans, but other petroleum fractions can alsobe treated for reduction of mercaptan content,v for example spirits, naphtha', kerosene, etc. Preferably, a petroleum fraction treated according to the invention has not been acid treated directly prior, or remotely prior, to the adsorbent treatment. Straight run or cracked petroleum fractions can be treated. However the yield of low-mercaptan products obtainable with straight run fractions is substantially greater than that obtainable with cracked fractions. It is believedthat, in-the-' case of cracked frac'tions,.these materials contain constituents such as phenols, etc. which become adsorbed on the adsorbent and interfere with the reduction of mercaptan content.

The process of the invention involves in some embodiments contacting hydrocarbons with an adsorbent prepared by contacting a fresh iron-containing adsorbent with an alkali; a fresh adsorbent being one which has not previously been used to reduce the mercaptan content of hydrocarbon materials. Preferably, excess alkali is removed from the alkali-treated adsorbent prior to use of the latter to treat hydrocarbons. However, in some cases this may not be necessary.

In copending application Serial No. 480,296, filed Jan uary 6, 1955, by the present inventors, a method for reducing the mercaptan content of mineral oil is disclosed and claimed, such method comprising contacting mineral oil containing mercaptans in liquid phase with magnetically separated bauxite containing about 20 to 70 weight percent of iron compounds as Fe O The invention claimed is:

1. Process for reducing the mercaptan content of hydrocarbons which comprises contacting hydrocarbons containing mercaptans in liquid phase in the presence of oxygen with a porous solid adsorbent treating agent which has previously been exposed to temperature not exceeding 1400 F., said treating agent having been prepared by contacting a porous solid adsorbent material containing iron compounds with an alkali and removing excess alkali and any excess moisture from the adsorbent by procedure comprising heating to a temperature above the volatilization temperature of water under the prevailing conditions but not substantially above 600 F., said treating agent containing combined water remaining after said heating.

2. Process according to claim 1 wherein said adsorbent is bauxite.

3. Process according to claim 2 wherein said adsorbent is magnetically separated bauxite containing about 10 to 70 Weight percent of iron as F 0 4. Process according to claim 1 wherein said alkali is an alkali metal hydroxide.

5. Process according to claim 4 wherein said removing is accomplished by washing the adsorbent with water until the pH of the effluent water is below 8.

6. Process according to claim 1 wherein the alkali is aqueous sodium hydroxide.

7. Process according to claim 6 wherein the amount of alkali employed is about 0.5 to 2 moles of alkali per mole of alumina in the bauxite.

8. Process according to claim 1 wherein said alkali is ammonia.

9. Process according to claim 1 wherein the adsorbent has been contacted with an aqueous solution of an iron compound prior to contacting with alkali.

10. Process according to claim 1 wherein the firstnamed contacting is effected at approximately atmospheric temperature.

11. Process according to claim 1 wherein said treating agent is prepared by saturating fresh granular bauxite 13. Process according to claim 1 wherein said hydrocarbons are straight run gasoline.

- 14. Process according to claim 1 wherein said hydrocarbons are cracked gasoline. f

15. Process according to claim 1 wherein said treating agent contains 1 to 25 weight percent of iron.

References Cited the file of this patent UNITED STATES PATENTS -.Hood et a1 June 28, 1910 Richter June 2, 1914 Phillips et al Oct. 16, 1928 Morrell et a1. May 8, 1934 Hoover May 26, 1936 Dolbear Apr. 18, 1939 Kolthofi et al July 29, 1941 Thomas June 22, 1943 La Landc Aug. 10, 1943 Frey June 5,1945 Agren June 24, 1947

Claims

1. PROCESS FOR REDUCING THE MERCAPTAN CONTENT OF HYDROCARBONS WHICH COMPRISES CONTACTING HYDROCARBONS CONTAINING MERCAPTANS IN LIQUID PHASE IN THE PRESENCE OF OXYGEN WITH A POROUS SOLID ADSORBENT TREATING AGENT WHICH 1400*F., SAID TREATING HAVING BEEN PREPARED BY CONTACTING A POROUS SOLID ADSORBENT MATERIAL CONTAINING IRON COMPOUNDS WITH AN ALKALI AND REMOVING EXCESS ALKALI AND ANY EXCESS MOISTURE FROM THE ADSORBENT BY PROCEDURE COMPRISING HEATING TO A TEMPERATURE ABOVE THE VOLATILIZATION TEMPERATURE OF WATER UNDER THE PREVAILING CONDITIONS BUT NOT SUBSTANTIALLY ABOVE 600*F., SAID TREATING AGENT CONTAINING COMBINED WATER REMAINING AFTER SAID HEATING.