US3183183A - Production of hydrocarbon feedstocks for petroleum sulfonates - Google Patents

Description

United States Patent 3,183,183 PRODUCTION OF HYDROCARBON FEEDSTOCKS FOR PETROLEUM SULFONATES Jack A. Guthrie, Media, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Fiied Jan. 16, 1962, Ser. No. 184,867 2 Claims. (Cl. 208-311) This application is a continuation in part of my copending application Serial Number 625,375, filed November 23, 1956, now abandoned.

This invention relates to the manufacture of sulfonic acids and salts thereof, and more particularly to the preparation of an improved sulfonate feed stock from petroleum oils of lubricating viscosity.

In commercial processes for the production of sulfonates from petroleum stocks, it has been the practice to first refine the stock by contacting with a selective solvent, such as furfural, phenol, sulfur dioxide, or other solvents which preferentially dissolve aromatics, and to recover a raflinate poor in aromatics, and an aromaticrich extract. The rafiinate, which may contain 5-15% of aromatics or other sulfonatable compounds, is then treated with concentrated sulfuric acid, oleum, or sulfur trioxide. Sulfonic acids formed by this treatment are neutralized and separated from the unsulfonatable oil, which is then further processed to a lubricating oil.

The foregoing procedure has two main disadvantages. The first is that the unsulfonatable oil will retain some acidic components which, although present in very small amounts, give rise to corrosion problems in further processing, and tend to give the finished lubricating oil an off-color appearance. econdly, since the charge stock to the sulfonator only contains a small proportion of sulfonatable material, large facilities must be provided to carry the inert material through the plant. In the past, attempts have been made to increase the amount of sulfonates obtainable from a plant of given size by using an unrefined petroleum fraction of lubricating viscosity as the feed thereto. These attempts have not proven successful, since the unrefined crude contains components which form an excessive amount of heavy sludge on contact with acid so that recovery of the valuable sulfonates is not commercially feasible because of the problems associated With handling and disposal of the sludge.

It is an object of this invention to provide a process for obtaining high quality mahogany and green acid sulfonates from an unrefined petroleum fraction of lubricating viscosity without adversely affecting the properties of the fraction useful as. a lubricating oil.

It is a further object of this invention to provide a feed stock for an existing sulfonation plant which will considerably increase the production of sulfonates from the plant over that obtainable when a solvent-extracted rafiinate fraction of a petroleum crude is processed.

I have found that the foregoing objects may be attained by first solvent extracting a petroleum fraction of Inbricating viscosity to obtain as a rafiinate the fraction which has previously been used as a sulfonation charge stock, and which comprises 5 to 15% sulfonatable material. This material is not, however, subjected to sulfonation, but is sent directly to lube oil processing, thus avoiding the corrosion and color dihiculties inherent in processing a lube stock which has previously been subjected to sulfonation. A primary extract is recovered which comprises an oil of higher aromatic content than the charge to the extractor, dissolved in the major portion of the solvent. This extract is subjected to flash distillation to remove a portion of the solvent, the bottoms from the flash distillation is mixed with a quantity of secondary extract recovered from a later stage of the process, the mixture is cooled to a temperature of from about 130 F. to 160 F., and is passed to a settler in which an upper oil layer or secondary raffinate and a lower solvent layer will form. The lower layer is treated to separate solvent and to recover a secondary extract, a portion of which is recycled to admixture Withthe primary extract.

I have further. found that when a portion of the secondary extract is recycled and mixed with the primary extract and the mixture subjected to settling, that the secondary raflinate comprises from 40 to 65 volume percent sulfonatable material. This is a much greater volume of sulfonatable material in the sulfonate feed stock than the volume produced by prior art feed concentration processes and thus the process of the invention affords the production of a large volume of high quality sulfonates from a relatively small amount of oil. Furthermore, the unsulfonatable portion of the secondary raffinate provides an excellent carrier or diluent for the sulfonate material.

The feed to the process is an unrefined petroleum fraction of the lubricating oil type. It has a viscosity ranging from to Saybolt seconds at 100 degrees R, a viscosity gravity constant of 0.820 to 0.840, a boiling range of 600 to 900 F., a specific gravity of 0.887 to 0.870. This feed contains from about 15 to about 35 volume percent aromatic hydrocarbons. It is contacted with a solvent selective for aromatic hydrocarbons at a temperature in the range of from about to 265 degrees F., preferably 170 to 235 degrees F. Any of the commonly used solvents for aromatic hydrocarbons is suitable including furfural, phenol, B,B-dichloroethyl ether (Chlorex), nitrobenzene, sulfur dioxide and diethylene-glycol. Solvent to oil ratios of 0.5 :1 to 3:1 are suitable. The primary extract is then passed to a flash tower for removal of solvent. From 10 to 50% of the solvent is removed. The primary extract solution contains from 60 to 90 volume percent aromatics, and represents from 20-40 vol. percent of the original lube oil fraction.

The primary extract is then subjected to phase separation in a conventional settler. Phase separation is accomplished at a temperature ranging from 130 to degrees F. The bottoms from the phase separator are passed to a flash tower and then to a stripper for the removal of solvent. The secondary extract recovered from the settler bottoms is the material recycled in the process of the invention. From 35 to 100 volume percent (based on the primary extract) can be recycled and added to the primary extract. As stated previously, this secondary extract is the principal means of adjusting the solvent to oil ratio of the primary extract prior to phase separation. It should be kept in mind, however, that some solvent adjustment is accomplished by flashing solvent from the primary extract and additional solvent adjustment is accomplished by means of a cooler located between the flash tower of the settler. Those skilled in the art will understand that it is possible to correlate the recycle of secondary extract with conditions in the flash tower and the cooler in order to arrive at the opti-- mum conditions in the settler.

The secondary raffinate is removed, is steam stripped to remove dissolved solvent, and is passed to a sulfonator' in which it is contacted with concentrated sulfuric acid,

oleum, or preferably sulfur trioxide, in quantity sufficient to sulfonate the sulfonatable materials contained therein. Sulfonation may be accomplished without dilution, but

in order to avoid emulsification and separation problems in subsequent steps of the process, I prefer to dilute the.

secondary rafiinate prior to sulfon ation with from one to three volumes of a nonreactive cycle oil recovered from a subsequent step. After the sulfonation, the sour oil is air blown to remove sulfur dioxide and unreacted sulfur trioxide and is separated into an oil layer and a sludge layer, which are separately worked up to recover mahogany sulfonates and green acid salts. The sulfonatable materials in the secondary raifinate are similar in composition to those in the primary raffinate heretofore used as a charge stock to a sulfonation process, since the quality of the product mahogany sulfonates is equally as good.

In order that those skilled in the art may more fully appreciate the nature of my invention and the method of carrying it out, an example showing the preferred conditions of operation for a commercial operation will be more fully described in connection with the accompanying drawing, which is a diagrammatic flow sheet of the invention.

A crude petroleum distillate charge stock of lubricating viscosity, boiling between about 600 F. and 900 F., is charged through line 1 to solvent extraction tower 2, at the rate of 3600 barrels per day (b./d.). In tower 2 the charge is countercurrently contacted with furfural introduced into tower 2 through line 3 at the rate of 6120 b./d. A temperature gradient is maintained in tower 2 ranging from 235 F. at the point of introduction of the furfural to 170 F. at the base of the tower. A primary raflinate stream comprising 2810 b./d. of oil and 420 b./ d. of furfural is recovered overhead through line 4. After solvent removal and dewaxing, the primary raffinate will yield a lubricating oil containing from 10.5% to 13% sulfonatable material by weight. The primary rafiinate has in the past been used as a feed stock for sulfonation, but according to the present invention, it is passed directly to the lube oil processing operations.

A primary extract comprising 790 b./d. of oil and 5700 b./d. of furfural is removed through line 5 and is passed through heater 6 to flash tower 7, from which 1840 b./ d. of furfural are taken overhead through line 8. An extract concentrate comprising 790 b./d. of oil and 3860 b./d. of furfural is removed from tower '7 through line 9 and is mixed with 370 b./d of secondary extract introduced through line 10, and the mixture is passed through cooler 11, in which its temperature is reduced to 150 F., to settler 12, in which the mixture phase separated into an upper oil layer, or secondary rafiinate, and a lower extract layer. The extract layer, comprising 765 b./d. of oil and 3805 b./d. of furfural is continuously removed from settler 12 through line 13, and is passed through heater 14 to flash tower 15, from which the major portion of the furfural contained in the extract phase is taken overhead through line 16. The extract, containing a small amount of furfural, is then taken through line 17 to steam stripper 18, from which the remainder of the furfural is removed overhead through line 19. Secondary extract, having an aromatic content of 92% by weight, is taken oif stripper 18 as bottoms through line 20 at the rate of 765 b./d. of which 370 b./d. is diverted by proportioning valve 21 to line for admixture with the primary extract concentrate, while the remaining 395 b./ d. is taken off to storage or other disposal via line 22.

The secondary raflinate, comprising 395 b./d. of oil and 55 b./ d. of furfural, is removed from settler 12 through line 23 and is passed to steam stripper 24, from which the furfural is removed overhead through line 25. A sulfonate feed stock, containing about 50% sulfonatable material by weight (45% by volume), and which boils in the range of 578 F. to 865+ F., is recovered from stripper 24 through line 26. This feed stock is then diluted with three volumes of an oil of the same boiling range from line 27. The diluent oil contains essentially no sulfonatable material, and is recovered from a later stage of the process, as will be more particularly described hereinafter.

The mixture of feed and diluent is then passed to sulfonator 28 in which it is contacted and mixed with anhydrous sulfur trioxide introduced through line 29 in the amount of 24 pounds per barrel of the mixture at a temperature of 165 F. The sulfonation products are then passed through line 30 to stripper 31 in which they are contacted with a stream of air from line 32, which serves to strip out unreacted sulfur trioxide and any sulfur dioxide formed in the reaction, these gases being taken off through line 33. The stripped sulfonation products are then taken through line 34 to settler 35, in which they are broken into an upper sour oil layer and a lower sludge layer. This latter layer, which contains oil and green sulfonic acids, is removed from settler 35 at the rate of 140 b./ d. and is 'passed through line 36 to neutralizer 37, in which it is contacted with sufficient aqueous caustic soda introduced through line 38 to neutralize the acids and to yield a 50% aqueous solution of sodium salts of green sulfonic acids, which is recovered through line 39.

The sour'oil is taken from settler 35 through line 41, and is mixed with 0.5 to 1 volume of aviation alkylate from line 42. The mixture is then passed to a mixer in which it is contacted with an alcoholic caustic solution from line 44. The neutralized stream passes to a settling vessel 43 where an oil layer comprising alkylate plus unsulfonatable oil from the feed to sulfonator 28 is recovered through line 45, while an aqueous solution comprising mahogany sulfonates, alcohol, water, and inorganic salts, is recovered through line 46. The oil layer is passed to still 47, from which alkylate is recovered through line 42 for admixture, after condensing, with the sour oil from settler 35, while unsulfonatable oil is recovered as bottoms through line 48. Of this oil 1185 b./d. is diverted through proportioning valve 49 to line 27 as diluent for the secondary ratiinate, the balance being diverted through line 50 to a later stage of the process. The mahogany sulfonate solution is taken to still 51, in which alcohol and a portion of the Water is taken overhead through line 52A, a product comprising mahogany sulfonates, inorganic salts, and about 30% water being removed through line 52. This product is mixed with an equal volume of isopropyl alcohol from line 53, and the mixture is passed to settler 54, where it is allowed to break into an upper layer consisting of a solution of mahogany sulfonates in isopropyl alcohol and a lower brine layer, which is Withdrawn through line 55 for further processing to recover dissolved alcohol. The sulfonate solution in alcohol is withdrawn from settler 54 through line 56 and is passed to still 57, from which alcohol is recovered overhead through line 58. Oil from line 50 is supplied to still 57 to yield a 60% concentrate of mahogany sulfonates in oil, which is withdrawn through line 59 to storage.

A number of advantages are obtained by proceeding according to the present invention. First, production of lubricating oil from a given charge stock may be substantially increased. In the example given, for instance, lubricating oil production was increased by 3,455 barrels per month by shifting from the primary raffinate to the secondary rafiinate as a feed to the sulfonation plant, while mahogany sulfonate production remained constant. Second, corrosion of the equipment used to process the lubricating oil is avoided. Third, the size of a plant for producing a given quantity per day of sulfonates may be considerably reduced as compared to a plant operating on primary raffinate charge. In the example given, the sulfonate section of the plant was designed to process a primary rattinate containing about 13% aromatics. Since the new secondary raffinate charge stock contained about 50% aromatics, it was diluted with three volumes of cycle oil to yield a feed to the sulfonator of the same character as that previously employed, in order to fill up the plant and enable it to operate efliciently. In designing a new plant, however, the cycle oil/feed ratio could be reduced to 1:1, to reduce the liquid charged to the sulfonator by one-half, with consequent substantial savings in plant investment and operating cost. Dilution of the feed with at least one volume of cycle oil is necessary, however, to keep the viscosity of the products from the sulfonator within manageable limits. A fourth important advantage is that a large part of the extract oil from extractor 2 is converted to sulfonation products far more Valuable than cracking stock, which is commonly the use made of the extra-ct oil.

The quality of the mahogany sulfonates produced from my new charge stock is equally as good as the sulfonates made from a primary rafiinate. A comparison of the properties of sulfonate concentrates prepared according to the example given above and those prepared from a primary raflinate is shown in the following table:

Table I Charge Stock Secondary Primary Rafilnate Ratfinate Sodium Sulfonatcs, Wt. Percent- 63.1 61. Sodium Garboxylates, Wt. Percen 0. 42 O. 25 Oil, Wt. Percent 30. 6 33.8 Inorganic Salts, Wt. Perccnt 0. 53 0.83 Water, Wt. Percent 4.0 3. 4 Average Mol. Wt 448 451 Color ASTM, 15% dilute 5% 5% The quality of the green acid sulfonates produced in the present process is superior to that of the prior art, as

As may be observed, the green acid sulfonates produced according to my invention contain far more sulfonates than those produced according to the prior art, and are an acceptable commercial product, whereas the green acids produced from the primary raffinate were so low in sulfonate content as to be unsalable and had to be disposed of by dumping.

From the foregoing description, it can be seen that large quantities of high quality concentrated sulfonation feed stock can be obtained by following the process of the invention. While solvent modifiers and anti-solvents have been used in the past to adjust solvent to oil ratios, it is believed that the employment of a recycle oil such as the secondary extract, according to the invention, represents a distinct advantage in that the concentrated feed stock can be sulfonated without further treatment.

I claim:

1. In a process for the preparation of feed stock for sulfonation to petroleum sulfonic acids which comprises the steps of:

(a) extracting a petroleum distillate fraction of lubricating viscosity having a boiling range of 600- 900 F. and containing from about 15 to about 35 vol. percent aromatic hydrocarbons with a selective solvent for aromatic hydrocarbons at a temperature in the range of from about 150 F., to about 265 F.,

(b) recovering a primary extract solution containing from to vol. percent aromatics,

(c) distilling a major proportion of the solvent from the primary extract solution,

(d) cooling said solution,

(e) subjecting said solution to phase separation at a temperature in the range of from F. to F. to produce an oil rich secondary ratiinate and a solvent rich secondary extract,

(f) recovering the secondary raflinate as said desired sulfonation feed stock,

(g) and removing solvent from said secondary extract to render said secondary extract substantially solvent free, the improvement comprising adding from 35 to 100 vol. percent of said solvent free secondary extract to said primary extractto adjust the solvent to oil ratio for phase separation.

2. The processes according to claim 1, in which the solvent for aromatic hydrocarbons is selected from the group consisting of furfural, phenol and diethylene glycol.

References Cited by the Examiner UNITED STATES PATENTS 2,514,733 7/50 Vold et al 260-504 2,527,404 10/ 50 De Vault 208--311 ALPHONSO D. SULLIVAN, Primary Examiner.

Claims (1)

1. IN A PROCESS FOR THE PREPARATION OF FEED STOCK FOR SULFONATION TO PETROLEUM SULFONIC ACIDS WHICH COMPRISES THE STEPS OF: (A) EXTRACTING A PETROLEUM DISTILLATE FRACTION OF LUBRICATING VISCOSITY HAVING A BOILING RANGE OF 600900*F. AND CONTAINING FROM ABOUT 15 TO ABOUT 35 VOL. PERCENT AROMATIC HYDROCARBONS WITH A SELECTIVE SOLVENT FOR AROMATIC HYDROCARBONS AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 150*F., TO ABOUT 265*F., (B) RECOVERING A PRIMARY EXTRACT SOLUTION CONTAINING FROM 60 TO 90 VOL. PERCENT AROMATICS, (C) DISTILLING A MAJOR PORPORTION OF THE SOLVENT FROM THE PRIMARY EXTRACT SOLUTION, (D) COOLING SAID SOLUTION, (E) SUBJECTING SAID SOLUTION TO PHASE SEPARATION AT A TEMPERATURE IN THE RANGE OF FROM 130*F. TO 160*F. TO PRODUCE AN OIL RICH SECONDARY RAFFINATE AND A SOLVENT RICH SECONDARY EXTRACT, (F) RECOVERING THE SECONDARY RAFFINATE AS SAID DESIRED SULFONATION FEED STOCK,

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