US 2755233 A
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United States Patent i ADDITION OF AN AQUEOUS SOLUTION OF A LOWER ALCOHOL TO AN ACID-LUBRICAT- ING OIL MIXTURE TO OBTAIN A PUMP- ABLE SLUDGE Jere C. Showalter, Baytown, Tex., assignor, by rncsne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware No Drawing. Application May 8, 1952, Serial No. 286,819
'10 Claims. or. 196-448 The present invention is directed to the acid treatment of lubricating oils. More particularly, the invention is directed to the acid treatment of lubricating oils and the formation of a pumpable acid sludge. In its more specific aspects, the invention is directed to a treating operation in which lubricating oil fractions are treated with sulfuric acid and a pumpable sludge is formed followed by neutralization of the separated acid oil without emulsion difficulties.
The present invention may be described briefly as in volving a process for separating a pumpable acid sludge from an acid treated lubricating oil fraction in admixture with said sludge, the particular feature of the invention being the addition to the admixture of the lubricating oil fraction and acid sludge of a small but effective amount of an aqueous solution of a water soluble aliphatic alcohol having from 1 to 4 carbon atoms in the molecule. The admixture containing alcohol is then settled and a pumpable acid sludge is separated from the treated lubricating oil fraction.
My invention also contemplates acid treatment of the lubricating oil fraction in combination with the subsequent addition of an aqueous solution of a water soluble aliphatic alcohol to form a pumpable sludge which is separated. I also contemplate the subsequent neutralization of the separated acid oil with a treating agent which does not form an emulsion with the acid treated lubricating oil fraction. In short, by addition of a water soluble aliphatic alcohol to the admixture of oil and sludge prior to settling and separating same and the neutralization of, the separated acid oil allows such a process to be employed in a continuous operation whereas heretofore without the ready settling and separation and the neutralization of the acid oil without formation of emulsions, it was necessary to provide extensive settling and separating times which required batch operations.
The lubricating oil fraction treated in accordance with the present invention may be any lubricating oil fraction, such as refined in modern petroleum refineries. It may be a lubricating oil fraction from a Coastal or Mid- Continent crude or it may be a lubricating oil fraction from a Pennsylvania type crude. It should suflice to say that my invention involves the acid treatment of any lubricating oil fraction which is normally subjected to such acid treatment.
The sulfuric acid employed in the practice of the present invention may be the commercial black acid usually available in petroleum refinery. It may be an alkylation spent sulfuric acid such as discarded from sulfuric acid alkylation operations. The sulfuric acid may be a concentrated sulfuric acid or any of the usual commercial acids having a Baum gravity of about 66 which is usually used in lubricating oil treating operations.
The amount of acid employed may range from about 5 pounds of acid per barrel up to about 50 pounds of acid per barrel and an amount in the range from about pounds of acid per barrel of oil up to about 35 pounds of acid perbarrel of oil will be preferred for most stocks.
The alcohols mentioned before may be used in an.
amount in the range between 0.1% and 1.0% by volumeas an aqueous solution containing from about 10% to about 50% by volume of alcohol. For example, an aque-- ous solution of isopropyl alcohol in an amount in the range between 0.5% and 0.75% based on the, acid oil of a 10% to 50% aqueous solution gives very satisfactory results.
The treating reagent employed to neutralize the sul furic acid treated oil will ordinarily comprise an aqueous solution of an alkali metal salt of preferably water-soluble sulfonic acids, such as a sodium salt of sulfonic acids, an alkali metal hydroxide, such as sodium hydroxide, and an alkali metal salt of an inorganic acid, such as sodium chloride or sodium sulfate.
The water-soluble sulfonic acid from which the alkali metal salts employed in the treating reagent are produced may be either an aromatic sulfonic acid or an alkyl sulfonic acid. For example, the sodium salt may be produced by neutralizing aromatic sulfonic acids resulting from the treatment of benzene, toluene and xylene with strong sulfuric acid. The treating reagent suitably may be prepared by neutralizing the acid treated oil produced in the formation of aromatic solvents. The aromatic sulfonic acids from which the salts are produced for use in the treating reagent may be obtained from acid solutions resulting from acid treatment of low molecular Weight lubricating oils, such as solvent oils having a viscosity of about SSU at F.
It is also possible to employ alkyl sulfonic acids in the preparation of the alkali metal salts of sulfonic acid for use in the treating reagent. For example, heptyl sulfonic acid neutralized with sodium hydroxide may be used. The other alkyl sulfonic acids, such as the other members of the series of paraffiuic hydrocarbons, such as hexane, octane, nonane, decane, undecane, dodecane and the like may be employed as starting materials for producing alkyl sulfonic acids. The neutralization agent may conveniently have a composition as follows:
Table Percent Alkali metal hydroxide 0.5 5 Alkali metal salt of sulfonic acid 10 -15 Alkali metal salt of inorganic acid 5 7.5 Water 72.5-84.5
The solution of the treating reagent should have a specific gravity no less than 1.10. Solutions of the treating reagent prior to dilution with water may range from 1.2 to 1.3 in specific gravity.
The treating reagent employed in the process of the present invention should contain the several components recited before. It is necessary to have the inorganic salt present to confer gravity differential between the oil being treated and the treating reagent to facilitate settling and prevent emulsions. The alkali metal salt of sulfonic acid is believed to act as a solutizer for the alkali metal salts of organic and inorganic acids which result from neutralization of such acidity with the free alkali metal hydroxide in the treating reagent. On omission of the alkali metal salts of sulfonic acid, the salts resulting from neutralization may remain in the oil and contribute to unsatisfactory results in that they may serve as nuclei for water and contribute to emulsion formation.
The alkali metal hydroxide in small amounts allows neutralization of organic and inorganic acidity and in the presence of the alkali metal salts of sulfonic acid and an inorganic acid is effective in neutralizing substantially larger quantities of organic and inorganic acidity than is possible conventionally.
When neutralizing acid oils resulting from treating such lubricating oil fractions as mentioned before, it will be desirable to use an amount of the treating reagent in the range from about 3% by volume based on the acid oil up to about by volume. Satisfactory results may be obtained employing about 3% by volume to about 6% by volume of the treating reagent described before.
The acid treatment of the lubricating oil fraction may be conducted in any type of suitable contacting equipment available in the modern petroleum refineries. The contacting operation may be done batch-wise but preferably a continuous operation followed by addition of an aqueous solution of a water soluble alcohol to the admixture of acid sludge and oil resulting from the treating operation is employed. The alcohol-containing admixture is then settled in the usual type of settling equipment and a separation made between the acid oil and the acid sludge after addition of the aqueous solution of water soluble alcohol. By virtue of adding the aqueous solution of water soluble alcohol to the admixture, it is possible to obtain a pumpable acid sludge and also to make a cleaner separation than was possible heretofore. As a result of such improved operations the yields of acid treated oil have been improved.
Similarly, the neutralization treatment with the treating reagent supra may be conducted in suitable contacting equipment and preferably on a continuous basis. The acid oil after separation from the acid sludge is admixed in the amounts given with the treating reagent to allow intimate contact of the treating reagent and neutralization of inorganic and organic acidity of the lubricating oil. As a result of such a contact the inorganic and organic acidities are neutralized and an oil of improved quality is obtained after suitable wash, for example, with hot water followed by settling to remove the wash water and drying as desired. My sequence of operations allows the process to be carried out without the attendant difficulties normally encountered in the prior art. Thus the employment of the aqueous solution of the aliphatic alcohol gives a clean and sharp separation of a pumpable acid sludge and the neutralization with the treating reagent eliminates the formation of emulsions which has plagued refiners of lubricating oil for over years.
The invention will be further illustrated by the following runs where, in one instance, a Coastal lubricating oil distillate was acid treated and after a sulficient settling time for complete reaction of the sulfuric acid with the lubricating oil distillate to form an admixture of acid oil and sludge, 0.3% by volume of 91% isopropyl alcohol was added to the admixture in 0.1% by volume increments. Thereafter 0.3% by volume of water was added in 0.1% by volume increments and the sludge coagulated and removed. The separated sludge was fluid and soft in texture.
A Coastal lubricating oil distillate was treated with sulfuric acid and the resulting admixture of acid oil and sludge was separated into two portions. The first portion had added to it 0.5% by volume of water. The second portion had added to it 0.5% of a 20% by volume aqueous solution of isopropyl alcohol. In both cases, the sludge coagulateed but the sludge separated from the portion to which water only was added was hard and mealy while the sludge recovered when alcohol was added was soft and fluid.
In a still further run, :1 Coastal lubricating oil distillate was treated with sulfuric acid and divided into two portions. In the first instance 0.7% of water was added to coagulate the sludge. To the second portion 0.7% of a 20% by volume isopropyl alcohol solution was added.
In the first case where water only was employed the sludge withdrawn was hard and mealy. Where the aqueous alcohol solution was used, the sludge withdrawn was soft and fluid. 1n addition to this improved result the yield of acid oil obtained in the second instance was 5.5% by volume greater than that in the first instance where water only was used to separate the acid sludge.
The acid oil such as obtained from the last operation described where aqueous alcohol was used may then be neutralized with 3% to 6% by volume of the treating reagent described above.
In a continuous operation a lubricating oil distillate may be contacted with suitable amounts of sulfuric acid, such as commercial sulfuric acid of 98% H2504 at a temperature from to P. which temperature results from heating the lubricating oil prior to acid treatment to remove any water which may be present therein. After the acid and the lubricating oil has been contacted for a sufiicient time for reaction to form a sludge, the admixture of acid sludge and acid oil then has admixed with it an aqueous solution of isopropyl alcohol such as one containing about 20% aicohol in a range from 0.5% to 0.75% by volume based on the acid treated oil. The acid sludge separates cleanly from the acid oil and may be withdrawn as a pumpable sludge while the acid oil is then admixed with about 3% to 6% by volume of the treating reagent described before and then allowed, after contacting a suflicient length of time, to settle with the treating reagent being withdrawn. The so-neutralized oil is then washed with hot water and the wash water removed. Following the wash with water the oil may be dried by heating and subjected to reduced pressure to flash off water vapor, if desired.
The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Pat out is:
1. A process for separating a pumpable acid sludge from an acid treated lubricating oil fraction in admixture with said sludge which comprises adding to said mixture an amount in the range between 0.5% and 0.75% by volume of an aqueous solution containing from about 10% to about 50% by volume of a water soluble aliphatic alcohol having from 1 to 1 carbon atoms in the molecule, settling the alcohol-containing admixture and separating a pumpable acid sludge from the treated lubricating oil fraction.
2. A process in accordance with claim 1 in which the alcohol is methyl alcohol.
3. A process in accordance with claim 1 in which the alcohol is ethyl alcohol.
4. A process in accordance with claim 1 in which the alcohol is a propyl alcohol.
5. A process in accordance with claim 1 in which the alcohol is a butyl alcohol.
6. A process in accordance with claim 1 in which the alcohol is isopropyl alcohol.
7. A method for treating a lubricating oil fraction which comprises contacting a lubricating oil fraction with sulfuric acid at a temperature in the range from 160 to 180 F. to form an admixture of lubricating oil and an acid sludge, adding to said admixture an amount in the range between 0.5% to 0.75% by volume of an aqueous solution containing from about 10% to about 50% by volume of a water soluble aliphatic alcohol having from 1 to 4 carbon atoms in the molecule, settling the alcoholcontaining admixture and separating a pumpable acid sludge from the treated lubricating oil fraction.
8. A process in accordance with claim 7 in which the alcohol is isopropyl alcohol.
9. A continuous process for treating a lubricating oil fraction which comprises contacting a lubricating oil fraction with sulfuric acid at a temperature in the range from 160 to 180 F. to form an admixture of said lubricating oil fraction and an acid sludge, adding to said admixture an amount in the range between 0.5% and 0.75% 1,233,700 Petrolf July 17 19 17 by volume of an aqueous solution containing from about 1,418,368 Ellis June 6, 1922 1.0% to about 50% by volume of a Water soluble aliphatic 1,938,322 De Groote et a1. Dec. 5, 1933 alcohol having from 1 to 4 carbon atoms in the molecule, 2,293,253 Galindo et a1. Aug. 18, 1942 settlin the alcohol-containing admixture, separating and 5 2,418,784 McCormick et a1. Apr. 8, 1947 separately recovering a pumpable acid sludge and the 2,487,103 Cone et al. Nov. 8, 1949 treated lubricating oil fraction, and neutralizing the treat- 2,581,064 Archibald Ian, 1, 1952 ed lubricating oil fraction with a treating reagent in an 2,685,558 Hodges Aug. 3, 1954 amount in the range from about 3% to 6% by volume OTHER REFERENCES comprising an aqueous solution of an alkall metal hy- 0 droxide, an alkali metal salt of an inorganic acid and an Rlchter: Orgamc Chmmstry: VOL Nordeman Publish alkali metal Salt of a sulfonic acid. ing (30., Inc., 215 4th Ave., New York, N. Y., pages 167-8 10. A process in accordance with claim 9 in which (1944)- the alcohol is isopropyl alcohol.
References Cited in the file of this patent UNITED STATES PATENTS i 1,196,274 Petrofi Aug. 29, 1916
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