US2653125A - Process for sweetening hydrocarbon oils - Google Patents

Description

Sept 22, 1953 J. H. KRAUSE PROCESS FOR SWEETENING HYDROCARBON OILS Filed Dec. 27, 1950 Illr INVENTOR.'

JACK H. KRAUSE @M ATTOZEY:

Patented Sept. Z2,V 1953 PROCESS FOR SWEETENING HYDRocARBoN oILs Jack H. Krause, Hammond, Ind., assignor to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application December 27, 1950, Serial No. 202,968

16 Claims. 1

This invention relates to an improved process for sweetening sour, i. e.y mercaptan containing, hydrocarbon oils. `More particularly, it relates to the production of sweet, color stable oils which boil in the range of 300 F. to 650' F., such as, heavy naphtha, kerosene, diesel oil, furnace oil and heater oil; these oils are commonly known as distillate fuels. Still more particularly, the invention is directed to an improved copper sweetening process.

One of the widely used processes for removing the sour odor present in most naturally occurring hydrocarbon oils, especially those obtained by distillation of crude' petroleum, is the socalled cupric chloride process.- .This process is described in S. patents Re. 20,938 and 2,042,051; and in more detail as to the coinrnercialV application in Oil and Gas Journal, March 22, 1947, page 195. It has been found that cupric chloride sweetened oil is not color stable, particularly at elevated temperatures. In the case of oils boiling within the gasoline range, this color instability is. easily overcome by the addition of very small amounts of a copper metal deactivator. However, it has beenl found that copper-'metal deactivators are relatively ineffective to stabilize the color of oils in the heavier-than-gasoline boiling range. With oils from some crudes, such as West Texas,

the cupric chloride sweeteningI process produces a color` degradation such that the freshly sweetened oil is of unsatisfactory color.

copper sulfate or preferentially water soluble,`

copper sulfonates, supported on an inert carrier and containing at least a certain minimum amount of water (about 8%) can be used to sweeten sour oils when the treating is carried out at a temperature in excess of about k190" F. in the presence of free oxygen. My preferentially water soluble copper sulfonates are selected from the group consisting ofV copper alkane sulfonates, withA not more than ten carbon atoms'therein and copper aryl sulfonates, with not more than la total of eight carbon .atems in Another object of an added copper metal deactivator.

The drawing which forms a part of this specication shows in schematic form one embodiment of a system for using my process.

This process "is applicable to any hydrocarbon oil containing mercaptans. It is particularly applicable to petroleum distillates Such as naphthas, kerosene, diesel oil, furnace oil 2nd heater oil. The distillates in the heavier-than-gasoline boiling range are especially suitable for treatment by this process because of the difficulty that exists in obtaining a color stable product when using the cupric chloride process. The following tests were made on a heater oil distillates obtained from West Texas crude and Mid- Continent ,crude and characterized as follows:

W. T. Acid W. T. Raw M. C. Raw

. Treated Dxstillate Distillate Distillate API Gravity 4o. s 4o, 9 41.5 M ercnptan number 3 8 The W. T. acid treated distillate was obtained by -treating raw West Texas distillate with 8 pounds of 98% sulfuric acid per barrel of distillate, separating the sludge, coalescing out the sludge pepper, neutralizing the oil with caustic and water washing to remove traces of caustic.

In all tests, the initial color of the sweet oil was determined immediately after washing or after separation of the catalyst and the color stability was determined by the color after an accelerated test. In the accelerated test, 100 ml. ofthe sweet'oil in an open beaker are maintained at 200 F. for 20 hours. A copper sweetened oil should have a satisfactory commercial storage color stability if its accelerated aged color is +10 Saybolt or better.

It has been` discovered that sweetening cannot be obtained `with copper sulfate or the preferentially water soluble copper sulfonates in the absence of water. Best results were obtained when the catalyst consisted of the copper salt,

water and en inert adsorbent support, such as fullers earth, Attapulgus clay, silica gel, activated carbon, alumina, etc. The catalysts used in my tests were made by adding the defined amount of Water to the copper salt, then adding the defined amount of Attapulgus clay nes and stirring the mass until the mixture was uniform. (All ingredients are on a weight basis The catalyst was a free-flowing granular material up to a total water content of about 45 weight per cent based on total copper salt, solids land vvatergl above this water content the catalyst `lest 'its free-flowing granular form and became a muddy solid.

The copper salts are preferably used the hydrate crystal form but the anhydrous form can be used. The water of vhydration .of the crystals must be considered in determining the total water content of the catalyst.

It has been found that either the C. P. grade or the commercial grade' of :copper'sulate can be used successfully. 'The .copper sultonate were prepared 'by reacting copper carbonate with the sulfonic acid. The particular copper Valkarre sulfonate used in the example :set .out herein was obtained from a lmixed methane 1(130 'Volume per cent), ethane (50%), 2-propane (10%) fsulonic acid and the rest lepropane and isobutane sulfonic acids. (This `mixed alkanesulfonic 'acid was prepared Vby the process disclosed In U. S.

2,433,395). It hes been found that the copper alkanesulfonates containing more than carbon atoms are so oil soluble that the catalyst .is rapidly destroyed. The copper arylsuli'onate's with more than eight carbon atoms "in the alkyl substituents are too -oil soluble tor luse in this process. I preferto use-copper benzenesuflstonate or copper toluenesulfonate.Y

The tests were carried `out as follows: The foil, 500 ml., was heated to the treating temperature in a flask equipped with a stirrer; the roil was saturated with oxygen by air blow-ing; the lcatalyst, 6 volume per cent based on oil, Was added to the oil and the mixture stirred for about two minutes while the temperature was maintained at the desired point. If the oil could be sweetened by the particular catalyst at the temperature of treatment, two minutes contacting `was more than enough time to produce a sweet oil; with good agitation of the catalyst-oil mixture the sweetening reaction proceeds very rapidly. The mixture was allowed ito settle for about 45 minutes and the treated oil separated. Usually the treated oil was washed with water, about one volume per two volumes of oil,V although more or less Water can be used. The oil-water mixture was allowed to settle for about ten minutes. The oil was decanted off and the suspended and dis; solved water removed by Aa salt filter. The temperature of the water washing 4operation is not important. It was found that for many oils, the water washing operation could be eli-minated without adverse elect on color stability.

Eyect :of treating temperature The effect of temperature on the .sweetening of the sour oil was determined by using a catalyst consisting of: clay, 72 weight per cent; Water, Weight per cent; copper salt, 8 Weight per cent. The Doctor test was used to determine are W. T. ACID TREATED 0IL Product Oil Treating Color Copper Salt Temper- Product Oil ature, F.

Initial Aged VSulfate l 150 sour Mixedlkanesulonate. 180 not quite sweet.. g Swzet..t 17 l3 5 no qui eswee m1uenesumM :1195 Sweet 22 19 M. G. OIL

sour 180 not quiteswect.. Sll'fate 20d, sweet 19 19 220 d 19 y, 122e do is i1 '.1805 sour v. MixedAlkarsulfonate 2200- not quiteswe l 22H7 sweet W T RAW'OIL isnl Sulfate l .20D .220.A 180 Mixed Alkenesulfonata 2(10 f. .229. sweet.. 16 l0 l No .water-washngater thesweetening step.

The specic'ationsfor distillate fuels for domestic hea-ting uses .require :an :oil of yless than one rnercaptan number; by the Doctor test, this is equal to an oil that is not quite sweet. This process can produce :a satisfactory oil in both sweetness and color .stability when .the reaction carried out -at about 190 F.; a completely sweet .oil is :obtainable by treating at about 200 F. With the very Worst oil, in regard to mercaptan content, a treating temperature of about 229 I'. .should .result a 'satisfactory product.

Eect 'of water Vcontent The eieet of total water 'content of the catalys-t on the sweetening of the sour 'oil was determin-ed by Vvarying the total water Ycontent and maintaining the weight ratio between the Aclay and "copper `sulfate at 9 to 1.

W. T. .ACID TBEATED VOIL lsour `do. r

Vto obtain a sweet product.

The data on the effect of total water Vcontent influence on the minimum water content needed to obtain a satisfactory product oil. Where the 3 mercaptan number acid treated oil can be sweetened at about 190 F. with about 8% water content, the mercaptan number oil needed a 20% water content at about 200 F.

Up to about 45 weight per cent water content the -catalyst is a free-flowing granular material; when more water is added, the free-flowing granular structure disappears and the mixture is a muddy solid which cannot readily be incorporated intooil. The data on 43% water content show a marked degradationof the initial color of the product oil and, in the case of the very high mercaptan oil feed oil, an unsatisfactory Vaged color.

Eect of copper content Tests were made on the sweetening ability of the catalyst when the total water content was held constant and the ratio of clay to copper sulfate varied. No noticeable effect on the sweetening ability of the catalyst was observed between clay to copper salt ratios of 12:1 and ratios of 3:1. When the clay to copper salt ratio is larger than 12:1, the copper content is so slight that an undue length of contacting time is necessary When the ratio is less than 3:1, a sweet product can be produced but other detriment, such as poor product color. may be encountered.

Comparison with cuprzc chloride process Product Oil Color Initi;l Aged M. C. Oil 19 2. W. T. Raw Oil -4 4 N. P. AJ. 'W. T. Acid Treated Oil -i 0 2 N. P. A.

W. T. Acid Treated Oil 2 -12 2% N. A.

l Sediment formed.

2 Treated at 220 F.

In all cases, a sweet product oil was obtained, but in no case did the cupric chloride process pro-Y duce a sweet oil of satisfactory color stability. In the treatment of the high mercaptan sulfur West Texas'oil, the original distillate color of about 20 was degraded to below the satisfactory point, 10 Saybolt color.

Referring to the drawing, the sour feed oil I0 should be free of either hydrogen sulfide or caustic. Ii the feed oil contains HzS, this can be removed with a simple caustic wash. The feed oil is passed through a rock salt filter in order to remove Vtraces of caustic remaining., iny the washed oil. From the salt filter Y|, the oil passes through line l2 to heater l5 where its temperature is raised to between 190 F. to 230 F., preferably about 200 F. It has been found that the hot oil removes the water from the catalyst with rapid deactivation thereof and that this adverse action can be slowed down, if not prevented, by saturating the hot oil with water before the hot oil comes into contact with the catalyst. Water,y

from a. source not shown, is passed by prepor- ,passes through line 40 into reactor 4|.

tionatingpumprnthrough line I8v into heater |9, where the water temperature is raised to about V200 F.l 'The hot water passes through line 20 into line I6 where it enters the hot oil stream; only enough water to saturate thehot oil is added. Commercial oxygen, or air, is introduced into the water saturated hot oil stream through line -22; the oxygen addition is dependent on the mercaptan content of the sour oil. Each 0.01 per cent -of mercaptan sulfur requires about 0.10 cubic :feet vof oxygen per barrel of sour oil. The combined 'stream then passes into mixer 25 where the oxygen is finely dispersed throughout the hot oil and any water droplets are broken up and are l,dissolved in the hotoil. The'water-saturated,-

oxygen-rich oil-stream passes by line 26 to pump 21 and on into line 30.

In slurry tank 32, the catalyst, which preferpumpable slurry with an amount of hot oil obtained from line |6 by way of line 34. The catalyst-oil slurry is forced by pump 36 through line 31 into line 30 where the catalyst meets the hot sour oil stream. The hot oil-catalyst stream Reactor 4| is a cone-bottom vessel; here the catalyst settles out of the sweet (or not quite sweet) oil. The catalyst is withdrawn from the reactor 4| by line 42 and may be discharged from the system through valved spent catalyst line 44. The oil passes from the reactor by line 41. Water is introduced from line 48 into line 41 and the wateroil stream is thoroughly intermingled in mixer 50. The purpose of this Water introduction is to remove particles of copper sulfate and fullers earth that are suspended in the sweet oil. The amount of water used may vary from 25 to 100 .volumes per volumes of oil, with about 50 volyurnes preferred. The water-oil stream passes .from mixer 50, through line 5| into settler 52.

'I'he wash water is withdrawn from settler 52 through line 53 to the sewer or it may be recycled to line 48 or to pump l1, if desired. The washed oil leaves settler 52 through line 55 and passes lthrough cooler 56 where its temperature is reduced to about ambient temperature. The cooled ,oil is passed through salt filter 58 to remove water and emerges therefrom as product oil and goes V by line 59 to storage (not shown).

It has been observed that sour oils having a mercaptan number above 0 cause a rapid deactivation of the catalyst even though theV oil theoretically contains enough oxygen to regenerate the catalyst. It is believed that the deactivation is primarily due to the dehydration of the cata- -lyst by the hot oil. This eiect can be overcome to some extent by saturating the hot oil with water before the oil contacts the catalyst. Also, the catalyst itself can be revivied by addition of -water to the spent catalyst-oil slurry and con- .tacting this with oxygen. By the use of these expedients, the life of the catalyst can be prolonged and the catalyst may be recycled instead of being discarded. Thus, if the oil feed is a '10 mer- ;captan number West Texas heater oil distillate,

fslurrypassesthro'uh mixer l'68 "wherefthe ireviyie cation' is completed; thereviviedcatalys't passes 'through Iline `-10 into feductor Y'H which is located on "a valv'ed byp'a's's of line f40. vThe eductor 'l-I causes the `fl`o`w through line 6-2, imiXer '63 and line 10. yThe stream in line 'l0 'mixes with the vhot sour 4oil and Ymake-up from the slurry tank 32 `and passes `the mixture through line fl!) into reactor 4l.

y When the sour -oil can be made into a product loil of satisfactory color stability without water washing, the washing step can be eliminated and the oil from'reactor v4I sent directly to cooler 56 l-b'y line 15. Other modifications and alternative 4operating procedures will be apparent from the above description to those skilled in the art.

I claim:

`|1. process '-'for sweetening mercaptan-#conmtaining hydrocarbon oils which comprises intimately Vcontacting said oil, in the liquid state, with la 'catalyst consisting of Ian inert adsorbent material, a copper salt and at least about 8 weight per 'cent' of wat-er, ata temperature between about 190 F. and 230 F., and in the presu k'ence or free-oxygen, wherein said lcopper salt is selected 'from the group consisting of vcopper sul;- fate and `prefere'ntially water soluble lcopper sul- 'fon'ates 2. A process for sweetening lsour petroleum loils which Vcomprises intimately contacting said oil, the liquid state, in the presence of free-oxygen, at a temperature between about 190 F. 'and 230 v1d". with a catalyst consisting of about 8 to 45 weight per cent water, and an inert adsorbent material and 'a copper salt in the ratio, on a weight basis, o'f between about 12:1 and 3:1, wherein said copper salt is selected from the group consisting of copper Vsulfate and preferentially water soluble copper sulfonates.

Y3. The .process of claim 2 where the treating temperature is from about 200 F. to 220 F.

4. The process of claim 2 wherein the copper -salt is copper sulfate.

5. The .process o1 clairn 2 Where 'the copper saltV is a copper alk-anesulfonate containing notr more than '10 carbon atomsfper molecule.

6. The Aprocess of 'claim 2 ,where the copper salt is fa copper aryls'ulfonate containing not .more than l8 carbon atoms in any alkyl substituent.

'1. The process of claim 2 where the copper salt is prepared from a mixed alkanesulfonic acid consisting oi methane sulfonic acid about 30 volume percent, ethanesulfonic acid about 50 Volume percent, propane sulfonic acid about 10 volume percent and the remainder, butano sulfonic acids.

8. The process of claim 2 wherein the copper salt is copper toluene sulfonate.

9. A process -tor sweetening sour petroleumoils having a mercaptan number of less than about 10 which comprises intimately contacting said sour oil in the liquid phase with a sweetening catalyst consisting of an inert adsorbent material and a copper salt, .in a weight ratio between 12:1 and 3:1J and water, between 8 and Ll() weight per cent, in the presence of a free-oxygen containing f'gas esistere between -fz'oo'rian'd 220i F.

and separa 'iig the :sweetened oil ironi said catalyst, wherein the copper salt in said 'Sweetehing catalyst lis 'selected from 'the y'group consisting of copper s'iilfate 'and preferentially water soluble -the liquid sourcil with a sweeten'ing catalyst consisting of an Yinert adsorbent material and a copper "salt, inea Weight 'ra'to between 12:1 and and 3:-1, and about 20 weight per cent water in the presence ora free-oxygen con-tain gas `at a temperature between 200 F. land "220 separating the sweetened oil from ysaid catalyst and water washing said l'sweetened oil, wherein the copper salt in said sweete-ning catalyst is selected from the `grou-p consisting-.of copper sulfate and preferentially water soluble copper sulionates.

11.v A 'process for making a sweet, color stable distillate fuel -iro'm a sour petroleum oil which process comprises intimately contacting said sour oil in the liduid phase in the presence oi freeoxygen at a temperature between 200 and 229 withra sweetening 'catalyst consisting of '60 to 'Z5 weight per cent'inert adsorbent material, 5 to 20 weight per cent 4of ya copper salt. and about 20 weight percent of water, and separating said catalyst from the sweetened oii, wherein said copper salt is selected from the `group consisting of copper sulfate and preferentially water soluble copper 4sulfonates. Y

12. The processor claim 11 wherein the copper salt is 'copper sulfate.

13. The process 'of claifr'i 11 'wherein the copper salt Vi's prepared "from a mixed alkanesulfonic acid consisting o1 methane sulfonic acid about 30 Volu'r'n'e percent, 'ethane sulcnic acid` about 50 volume percent, propane sulonic acid about l0 volume percent and the remainder, butane sul- -fon-ic acids.

14. The process 'of claim 11 wherein the copper salt is copper toluene sulfonate.

15. The process of claim 11 wherein the sweetened oil from the separating step 'is washed with Water.

16. rThe process of claim 11 wherein the sweetening catalyst consists of about 12 weight per cent fullers earth, about 8 weight per cent copper sulfate Yand about 2O Weight per cent water.

JACK H. KRA'USE.

References Cited in the iile of this patent 'Nrinh STATES PATENTS Number Name Date 2,094,485 Buell Sept. 28, 1937 2,111,487 Chaney et al. N/ar. 15, 1938 2,204,234 Schulz June 11, 1940 2,297,650 Fry et ail. Sept. 2Q, 1942 2,338,371 Workman Jan. 1944 2,539,808 Brooner Jan. 30, 1951 2,593,464 Krause Apr. 12, 1952

Claims (1)

1. A PROCESS FOR SWEETENING MERCAPTAN-CONTAINING HYDROCARBON OILS WHICH COMPRISES INTIMATELY CONTACTING SAID OIL, IN THE LIQUID STATE, WITH A CATALYST CONSISTING OF AN INERT ADSROBENT MATERIAL, A COPPER SALT AND AT LEAST ABOUT 8 WEIGHT PER CENT OF WATER, AT A TEMPERATURE BETWEEN ABOUT 190* F. AND 230* F., AND IN THE PRESENCE OF FREE-OXYGEN, WHEREIN SAID COPPER SALT IS SELECTED FROM THE GROUP CONSISTING OF COPPER SULFATE AND PREFERENTIALLY WATER SOLUBLE COPPER SULFONATES.

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