US2593464A - Process for sweetening hydrocarbon oils - Google Patents

Description

April 22, 1952 J. H. KRAusE PROCESS FOR SWEETENING HYDROCARBON OILS Filed Deo. 27, 195o INVENTOR.'

JACK H. KRAUSE BYS ATTORNEYI Patented Apr. 22, 1952 UNITED STATES PATENT OFFICE PROCESS FOR SWEETENING HYDRooARBoN oILsy Jack H. Krause, Hammond, Ind., assignor to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application December 27, 1950, Serial No. 202,969

This invention relates to an improved process for sweetening sour, i. e. 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,

described in U. S. Patents Re. 20,938 and 2,042,051; and in more detail as to the commercial 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 o f 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 been found that copper metal deactivators are relatively ineiective 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 sweetening process produces a color degradation such that the freshly sweetened oil is of unsatisfactory color. v

An object of this invention is to produce a sweet hydrocarbon oil from an oil which contains mercaptan compounds. Another object is to produce a sweet, color stable distillate fuel4V without the addition of copper metal deactivators. i A particular object is to sweeten mercaptan containing hydrocarbon oils by using a -copper fluoride catalyst for the conversion of `the mercaptan. A further object is to sweeten sour oil with little color degradation.

I have discovered that a catalyst consisting` of Copper fluoride supported on an inert carrier and containing at least a certain minimum 8 Claims. (Cl. 196-29) 2 iication 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 and heater oil. The distillates in the heavier-thangasoline boiling range are especially suitable for treatment by this process because of the difii- 10 culty that exists in obtaining a color stab-1e product when using the cupric chloride process. The following tests were made on heater oil distillates obtained from West Texas crude and Mid-Continent crude and characterized as follows:

W. T. wfr. M. C. Raw Acid Treated Raw Distillate Distillate Distillatc API Gravity 40. 3 40. 9 41.5 Mercaptau number- 70 3 8 Saybolt color +19 +20 +22 ASTM Distllation:

IBP 330 330 327 lo? 390 22 ii? 50 445 o 90%? 50o 50s .517 Max 544 554 554 The W. T. acid treated distillate was obtained by treating raw West Texas distillate with 8 pounds of 98% sulfuric acid per barrel of. disamount of water (about 8%) can be used to sweeten sour oils when the treating is carried out at a temperature in excess of about 190 F..

.in the presence of free oxygen. The life' of the catalyst can be extended by introducing oxygen "or a free-oxygen containing gas into the oil befor the oil contacts the catalyst. My process degrades the initial color of the oil only slightly and produces a color-stable oil without the use of an added copper metal deactivator.

vated carbon, alumina, etc.

tillate, 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 washingv 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. of the sweet oil in an open beaker are maintained at 200 for 20 hours. A copper sweetened oilshould 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 uoride in the obsence of water. Best results were obtained when the catalyst consisted of copper fluoride, water `and an inert adsorbent support, such as .fullers=earth,fAttapulgus clay, silica gel, acti- The catalysts used in my tests were made by adding the defined amount of water to lcopper uoride, then iadding the defined amount of Attapulgus clay fines and stirring the mass until the mixture was uniform; (-All ingredients are on a weight The drawing which forms a part of-thi's speci-f basis.) The catalyst .was a free-owing granular material up to a total water content of about 45 weight per cent based on total copper fluoride, solids and water; above this water content the catalyst lost its free-flowing granular form and became a muddy solid.

The copper fluoride is preferably used in the hydrate crystal form but the anhydrous form can be used. The water of hydration 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 of the commercial gradev of copper fluoride can be used successfully.

The tests were carried out as follows: The oil, 500 ml., was heated to the treating temperature in a flask equipped with a stirrer; the oil was saturated with oxygen by air blowing; the catalyst, 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 to 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, although more or less water can be used. The oilwater mixture was allowed to settle for about ten minutes. The oil was decanted oi and the suster. The temperature of the water washing operation is not important. It was found that for many oils, the water washing operation could be eliminated without adverse effect on color stability.

Eect 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, 20 weight per cent; copper fluoride, 8 weight per cent. The doctor test was used to determine whether the oil was sweet or sour. All colors are on the Saybolt scale. The initial color is that of the oil immediately after sweetening (or water washing) and the aged color is after the accelerated aging procedure.

Product Oil Color Product Oil Treating Temperature F.

Initial Aged YV. T. ACID TREATED OIL sour.-. not quite sweet..

W. T. RAW OIL sour not quitesweet.. sweet 1G 10 1 No Water washingater the' sweeteningstep.

Effect of water content The eiect of total water content of the catalyst on the sweetening of the sour oil was determined by varying the total water content and maintaining the weight ratio between the clay and copper fluoride at 9 to 1.

Water Con- Treating Product Oil Color tent Weight Tempera- Product Oil Per cent turc F.

Initial Aged YV. T. ACID TREATED OIL sour 200 not quite sweet.. 220 sweet 12 12 W. T. RAW OIL vthe mercaptan number of the feed oil has some 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 F. with about 8% water content, the 70 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 into oil. The data on 43% water content show a marked degradation of. the initial color of the product oil and, in the case of the very high mercaptan oil feed oil, an unsatisfactory aged 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 uoride. varied'. No noticeable effect on the sweetening ability of the catalyst was observed between clay to copper vsalt 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 to obtain afsweet product. 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. y

Comparison with cuprz'c chloride process For comparative purposes, the three sour oils I `conventional treating temperature of 115 F.

Product Oil Color Initial Aged 1 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 produce 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, Saybolt color.

Referring to the drawing, the sour feed oil I0 should be free of either hydrogen sulfide or caustic. If the feed oil contains HzS, this can be removed with a simple caustic wash. The feed oil is passed through a rock salt filter I I in order to remove traces of caustic remaining in the washed oil. From the salt lter I I, the oil passes through line I2 to heater I5 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, from a source not shown, is passed by proportionating pump I1 through line I8 into heater I9, where the Water temperature is raised to about 200 F. The hot water passes through line into line I6 where it enters the hot oil stream;

only enough water to saturate the hot 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 of oxygen per barreLof sour oil. The combined stream then passes into mixer 25 where the oxygen is nely dispersed throughout the hot oil and any water droplets are broken up and are dissolved in the hot oil. The water-saturated, oxygen-rich hot oil stream passes by line 26 to pump 21 and on into line 30.

In slurry tank 32, the catalyst, which preferably consists of 72 weight per cent fullers earth, 8 weight percent copper fluoride and 20 weight per cent water, from source 33 is formed into a pumpable slurry with an amount of hot oil obtained from line I6 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 passes through line 40 into reactor 4I. Reactor 4I 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 4I 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 water-oil stream is thoroughly intermingled in mixer 50. The purpose of this water introduction is to remove particles of copper fluoride and .fullers earth that are suspended in the sweet oil. The amount of water used may vary from -25 to 100 volumes per 100 volumes of oil, with about -50 volumes preferred. The water-oil streampasses from mixer 50, through line 5I into -settler 52. The wash water is withdrawn from settler 52 throughv line 53 to the sewer or it may be recycled to line 48 or to pump I1, if desired. The washed oil leaves settler 52 through line 55 and passes through cooler 56- where its 'tempera-ture 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 by line 59 to storage (not shown).

It' hasbeen observed that sour oils having a mercaptan number above 10 cause a rapid deactivation of the catalyst even though the oil theoretically contains enough oxygen to regenerate the catalyst. It is believed that the deactivation is primarily due to the dehydration of the catalyst by the hot oil. This effect 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 contacting 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 70 mercaptan number West Texas heater oil distillate, valve 43 can be shut and the catalyst from the bottom of the reactor 4I sent to valved line 62. Water in the amount needed to bring the catalyst to the desired content, preferably 20 weight per cent, is passed through heater 64 where it is heated to about 200 and then through line 65 into line 62. Oxygen is passed through line 61 into line 62. The oxygen-free water-catalyst-oil slurry passes through mixer 68 where the revivication is completed; the revivied catalyst passes through line I0 into eductor 1I which is located on a valved bypass of line 40. The eductor 1I causes the flow through line 62, mixer 68 and line 10. The stream in line 10 mixes with the hot sour oil and make-up from the slurry tank 32 and passes the mixture through line 40 into reactor 4 I.

When the sour oil can be made into a product oil of satisfactory color stability Without water washing, the washing step can be eliminated and the oil from reactor 4I sent directly to cooler 56 by line 15.

Other modifications and alternative operating procedures will be apparent from the above description to those skilled in the art.

I claim:

1. A process for sweetening mercaptancontaining hydrocarbon cils which comprises intimately contacting said oil, in the liquid state, with a catalyst consisting essentially of an inert adsorbent material, copper fluoride and at least about 8 weight per cent of water, at a temperature between about F. and 230 F., and in the presence of free-oxygen.

' 2. A process for sweetening sour petroleum oils which comprises intimately contacting said oil, in the liquid state, in the presence of free-oxygen, at a temperature between about 190 F. and 230o F. with a catalyst consisting essentially of about 8 to 45 weight per cent water, and an inert adsorbent material and copper uoride in the ratio, on a weight basis, of between about 12:1 and 3:1.

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

4. A process for sweetening sour petroleum oils 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 essentially of an inert adsorbent material and copper fluoride. in a weight ratio between 12:1 and 3:1, and water, between v8 and 40 weight per cent, in the presence of a free-oxygen containing gas at a temperature between 200 F. and 220 F. and separating the sweetened oil from said catalyst.

5. A process for producing a sweet, color stable distillate fuel from a sour petroleum oil having a mercaptan number less than about 80 which process comprises intimately contacting the liquid sour oil with a sweetening catalyst consisting essentially o an inert adsorbent material and copper fluoride, in a weight ratio between 12:1 and 3:1, and about 20 weight per cent water in the presence of a free-oxygen containing gas at 8 a temperature between 200 F. and 220 F., separating the sweetened oil from said catalyst and water washing said sweetened oil.

6. A process for making a sweet, color stable distillate fuel from a sour petroleum oil which process comprises intimately contacting said sour oil in the liquid phase in the presence of freeoxygen at a temperature between 200 F. and 220 F. with a sweetening catalyst consisting essentially of 60 to 75 weight per cent inert adsorbent material, 5 to 20 weight per cent of copper fluoride, about 20 weight per cent of water, and separating said catalyst from the sweetened oil.

'7. The process of claim 6 wherein the sweetened oil from the separating step is washed with water.

8. The process of claim 6 wherein the sweetening catalyst consists essentially of about 72 weight per cent fullers earth, about 8 weight per cent copper fluoride and about 20 weight per cent water.

JACK H. KRAUSE.

No references cited.

Claims (1)

1. A PROCESS FOR SWEETENING MERCAPTANCONTAINING HYDROCARBON OILS WHICH COMPRISES INTIMATELY CONTACTING SAID OIL, IN THE LIQUID STATE, WITH A CATALYST CONSISTING ESSENTIALLY OF AN INERT ADSORBENT MATERIAL, COPPER FLUORIDE 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.

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