US2578657A

US2578657A - Process for producing sulfonic acids and sulfonates

Info

Publication number: US2578657A
Application number: US45588A
Authority: US
Inventors: Henry W Anderson; Otto A Samson; Augustus W Clark
Original assignee: Shell Development Co
Current assignee: Shell Development Co
Priority date: 1948-08-21
Filing date: 1948-08-21
Publication date: 1951-12-18
Anticipated expiration: 1968-12-18

Description

Patented Dec. 18, 1951 PROCESS FOR PRODUCING SULFONIC ACID AND SULFONATES Henry W. Anderson, Martinez, Otto A. Samson, Concord, and Augustus W. Clark, Albany, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application August 21, 1948, Serial No. 45,588

Claims.

This invention relates to the preparation of organic sulfonic acids and sulfonates, and particularly to sulfonic acids and their derivative salts which may be prepared by the treatment of :petroleum oils with a sulfonating agent. The invention is concerned more particularly with the preparation of oilsoluble petroleum sulfonic acids and sulfonates, often designated mahogany sulfonic acids and sulfonates.

It is well known to acid-treat various hydrocarbon oils with strong sulfuric acid for the purpose of improving certain qualities of the oil, by removing substances therefrom which impart undesirable properties to the oil. Various reaction products are formed in this treatment, including sulfonic acids, some of which are oil-soluble and some oil-insoluble or water-.soluble, the amounts depending upon factors such as the nature of the oil, the severity of acid-treatment, and the like. It is also well known to recover these sulfonic acids by various methods, as incidental to the purification of the oil. Various methods are also practiced where the principal purpose is to produce either oil-soluble, mahogany, acids or water-soluble, green acids, or both, since the former have been found to be of increasing value in hydrocarbon oil compositions, such as lubricating compositions, and the latter are particularly valuable in the preparation of insecticidal spray compositions.

In the preparation of oil-soluble mahogany acids and soaps, it has been the general practice to treat a suitable oil stock, such as a lubricating oil distillate, with a suitable sulfonating agent such as concentrated or fuming sulfuric acid at normal atmospheric or elevated temperatures, and with agitation, until satisfactory reaction takes place, to permit the reaction mixture to stand in a quiescent state so that the formed sludge, generally containing resinous material, excess acid and oil-insoluble sulfonic acids, may separate as a lower layer from the oil and oilsoluble sulfonic acids dissolved therein. After separation of the two layers, the sulfonic acids in the oil layer are recovered therefrom, either as the free acid or salt thereof, by extraction with an aqueous alcoholic solution of a lower molecular weight alcohol, such as methanol, ethanol, and propanol. The solvent is then distilled from the aqueous alcoholic solution of the neutralized acid to yield the sulfonate, generally admixed with a substantial proportion of 'oil and an appreciable amount of inorganic salts. Various methods have been proposed for subsequent purification of the sulfonates.

in the oil phase in the practice of the foregoing method, as applied to the rafiinate from a solvent extraction of a lubricating oil distillate fraction, have been found to be of the order of five to nine per cent, based on the weight of the oil charge.

It is a principal object of this invention to provide an improved process for the preparation of oil-soluble petroleum sulfonic acids and their salts. A further object is to increase the yield of sulfonic acids separated in the oil phase of a sulfonation treatment of hydrocarbon oils. Another object is to increase the recovery of mineral oil in the sulfonation process. A more specific object is to provide a method whereby a hydrocarbon oil concentrate of oil-soluble petroleum sulfonates in higher concentration is obtainable directly from a sulfonation treatment of a hydrocarbon oil, or fractions thereof, particularly a solvent extraction raflinate of a petroleum oil distillate fraction having lubricating viscosity.

Now, in accordance with the present invention,

.it has been found that an improved yield of oilsoluble petroleum sulfonates in the oil phase and an increase in.yield of oil phasegreater than can beaccounted for solely on the basis of increased recovery of sulfonic acids, indicating that some mineral oil which would otherwise be retained in the sludge phase is transferred to the. oil phase. is obtained by the method which comprises in combination the steps of, intimately contacting a hydrocarbon oil, preferably of naphthenic character and of lubricating viscosity, with a suitable sulfonating agent, such as fuming sulfuric acid, chlorsulfonic acid, sulfur trioxide in the presence of sulfur dioxide or other suitable catalyst, and preferably concentrated, including fuming, sulfuric acid, under suitable conditions of time and temperature to effect substantial sulfonation of the hydrocarbon oil and thereafter, and preferablybefore sludge separation, admixing a predetermined proportion of water with the reaction mixture to produce, upon being allowed to stand in a quiescent state, a lower aqueous acid layer and an upper oil layer, and separating the two layers, the proportion of water being such as to produce an aqueous acid phase of from about 50% to about sulfuric acid concentration. The proportion of water added will depend, as will be readily understood, on the concentration of the sulfonating acid at the time the water is added, which, in turn, will depend on the original acid concentration, the ratio of acid used to oil charge, and the proportion of sulfonatable materials present in the oil under the conditions of sulfonation.

Representative yields of sulfonates recovered By practicing the present invention. as deavas 3 scribed broadly hereinbefore, anumber of serious problems encountered in prior methods are at least partially or substantially entirely obviated. Thus, where the addition of small amounts of water to the sulfonation mixture has been proposed, with more than a few per cent of water addition there results the formation of two sludge phases, one a dilute acid phase, the other a thick,

difiicultly pumpable, tar phase, the proportion of tar phase increasin with an increase in the proportion of water added. It has now been found, however, that maximum tar separation is reached when water is added in amount to separate a sludge acidity in the range of about 75% to about 80% sulfuric acid concentration, as may be produced when about by weight of water is added, based on the weight of equivalent 100% sulfuric acid present. The addition of still larger proportions of water results in the separation of smaller amounts of tar with the amount being of the order of only 0.1% to 0.3% by weight, based on the oil charge, for sludge acidities below about 65% by weight sulfuric acid. The resulting sludge mixture is readily pump able. On the other hand, as the acid sludge is diluted with water its corrosive action on metal equipment which is normally used in the settlers and the like increases rapidly so that there is a limit to the amount of dilution which is permissible. For an acidity corresponding to about 100% sulfuric acid the corrosion is at a minimum, but below a concentration of about 60% sulfuric acid, the corrosivity is rapidly approaching a value which cannot be tolerated. Considering the two factors, pumpabality (tar separation) and corrosivity, it may be stated that in general the addition of sufficient water to give a sludge acidity of from about 50% to about 70% sulfuric acid, and preferably from about 60% to about 65% sulfuric acid, to the sulfonation mixture immediately after the sulfonation and prior to appreciable sludge separation, results in a readily pumpable sludge and one which is substantially non-corrosive.

Another problem is the rate of separation of the sludge and oil phases. Although it has been proposed to add 100% or more of water, relative to the acid, particularly in the preparation of water-soluble, green acids from light, non-lubrieating, hydrocarbon oils, such as kerosene and stove oil, in order to increase the recovery of water-soluble acids. and -it might be expected that such dilution would enhance phase separation due to dilution of the acid, it has been found that in the present invention, concerned with recovery of mahogany acids, after sulfonation treatment, the sludge settling rate, or phase separation rate, is at a maximum when the sludge acidity is between about 70% and about 75% sulfuric acid, corresponding in general to the addition of from about to about water, with the rate decreasing both as the sludge acidity is decreased or as it is increased. From the standpoint of sludge settling rate, it is preferred to adjust the sludge acidity at 70% to 75% sulfuric acid but settling rates are still satisfactory and substantially higher than the rate when no water is added at sludge acidities as low as sulfuric acid.

Now, concomitant with the foregoing-described advantages gained by the dilution step with water, it has also been found that the amount of sulfonic acid separated in the stratified oil layer is materially increased, represen- 10% to about 18% by weight, based on the oil charge, the maximum recovery being found at a sludge acidity of about to sulfuric acid and beginning to drop offrapidly at sludge acidities greater than about Having set forth various advantages to be gained in the practice of the invention, the manner in which the invention is to be practiced will be described in greater detail.

Various petroleum hydrocarbon oils and fractions thereof, particularly those which possess lubricating properties, and are of the so-called mixed type, i. e. containing naphthenic type hydrocarbons, may be utilized for the preparation of oil-soluble sulfonates by the process of this invention. In general, it is preferred to use hydrocarbon oil fractions derived from naphthenic Gulf Coastal, Mid-Continent or California oils, and particularly the lubricating oil fractions obtained from such crudes. Prior to sulfonation the oil may be solvent treated.

A naphthenic oil which is particularly useful for the production of the oil-soluble sulfonic acids may be a furfural or an Edeleanu rafllnate of a naphthenic oil distillate having the followin properties:

Viscosity SSU at 100 F 40Qt0 900 Viscosity index 30to 60 Gravity, API 22 to 27 Refractive index N 1.48 to 1.51 Flash (0. O. C.) F 380 to 450 tative recoverable amounts being from about 75 Representative of suitable oil stocks which have been used were 33 V. I. and 55 V. I. rafiinates from solvent extraction of 60 SSU at 210 F. bulk distillates derived from an /20 Poso/Coalinga, California crude mixture. The solvents may be sulfur dioxide, furfural, phenol or the like.

The method of obtaining the advantages of the invention is illustrated by the following example.

A 55 V. I. rafilnate, as described hereinbefore. was intimately contacted with 20% of its weight of 105.5% fuming sulfuric acid (25% S03), 103.5% to 105.5% acid generally being preferred,

, while maintaining the temperature below about 150 F., and generally above about 75 F., preferably above F., for a period of about 10 minutes. Higher temperatures, such as up to about 200 F., may be used for shorter periods of time. Most of the sulfonation is completed within about ten minutes, a further small amount of sulfonation being effected when the time is extended to about 30 minutes. Excessive contacting times may result in sludge separation during the sulfonation, which it is desired to avoid in the present invention. The contacting of the oil and sulfuric acid may be readily carried out in a single stage operation as in a batch process or any other operation as will be understood which lends it self to the practice of the invention. After the oil-acid mixture had been intimately contacted for 10 minutes, an amount of water squivalent to 25% by weight of the weight of fuming acid used, 1. e. 5% by weight of the oil charge, was added, in the absence of any neutralizing basic substance, mixed thoroughly with the reaction mixture, and the phases allowed to stratify. The separated oil phase represented about 97% by weight of the oil charge and contained 11.5% by weight of sulfonic acid. The separated aqueous sludge layer had an acidity of about 70% by weight hydrogen sulfate (H2804) was readily pumpable, and was not excessively corrosive to.- ward the iron settling vessel and carrying lines.

When another charge of the same oil was treated as in the foregoing example, except that no water was added prior to settling and stratiflcation of the different reaction-mixture phases, the separated oil phase amounted to only about 86% of the charge and the sulfonic acid content thereof was only about 6% by weight.

In another case similar to the foregoing examples, but adding about 45% watenthe separated oil layer was about 99% by weight of the oil charge and it contained approximately 13.5% by weight of sulfonic acids.

In still another instance similar to the first above-described example, but using 30% by weight acid dosage and 33% subsequent water addition, the separated oil layer contained about oil-soluble sulfonic acids. By the use of a still higher acid dosage, such as 50%, and a corresponding water addition to yield a sludge phase of approximately 70% acidity, an oil phase has been obtained which contained about 18% by weight of oil-soluble sulfonic acids.

The separated oil solutions of sulfonic acids as prepared in the foregoing examples in accordance with the invention were converted to 'oil solutions of the corresponding calcium petroleum sulfonates by methods well known to the art, such as by reacting directly with calcium oxide or hydroxide, or with an aqueous mixture of calcium chloride and calcium hydroxide, or by converting to an oil solution of the sodium sulfonate by reaction with a sodium alkali compound and then conversion of the sodium salt to the calcium salt by metathetical reaction. The concentrates of calcium petroleum mahogany sulfonates thus produced were found to be highly effective in the production of motor lubricating oils and other oil compositions containing the sulfonate. 4

Thus, the practice of the invention makes it possible to obtain a greater recovery of oil-soluble sulfonates in the oil solution. An important advantage derivable therefrom is that the resulting sulfonate solution contains a higher concentration of active ingredients and consequently, smaller amounts of the oil carrier (in the concentrate) need be incorporated with the oil to which it is desired to add the sulfonates.

The reason why the practice of the invention results in a greater concentration of the oil-soluble sulfonates in the oil is not known with any degree of certainty. However, and without being limited as to any theory concerning the matter, it may be that the water addition prior to sludge separation minimizes further reaction, including possible polymerization of already-formed oilsoluble sulfonates, and/ or further sulfonation to oil-insoluble disulfonic or polysulfonic acids, and also that the water addition at that time results in a sulfuric acid phase which is not capable of retaining an appreciable proportion of the oilsoluble sulfonates in solution therein, which otherwise would be capable of carrying oil-soluble sulfonic acids into the sludge phase. The facts appear to indicate that the increased recovery of oil-solub l sulfonic acids in the oil phase is not attributable solely, if at all, to a transfer of water-soluble and normally oil-insoluble sulfonic acids into the oil phase.

We claim as our invention:

1. A process for the production of an oil solution of oil-soluble petroleum sulfonic acids dissolved in a highly refined lubricating oil fraction, which process comprises intimately contactinga mineral lubricating oil raflinate fraction of naphthenic character, having a viscosity at 100 F.

of at least about 400 SSU, a viscosity index of from about 30 to 60, a flash point of atv least about 380 F., and having been obtained as rafiinate fraction from a selective solvent extraction of a naphthenic mineral lubricating oildistillate fraction, with 20% to 50% by weight, based on the oil charge, of 105.5% fuming sulfuric acid, at a temperature between about F. and 150 F. for a period of about 10 minutes, thereafter immediately and before the separation of a sludge phase, intimately mixing the resulting reaction mixture with from about 25% to about by weight of water, based on the acid used, selected to yield a separated acid sludge phase with an acidity of from about 50% to about 70%, permitting the resulting admixture to stratify wherea by only two layers are formed, an oil layer containing dissolved oil-soluble petroleum sulfonic acids and an acid sludge layer, and separating the layers.

2. A process for the production of an oil solution of oil-soluble petroleum sulfonic acids, which process comprises intimately contacting a mineral lubricating oil rafllnate fraction of naphthenic character, having a viscosity at F. of at least about 400 SSU, a viscosityindex of from about 30 to about 60, a flash point .of at least about 380 F., and having been obtained as a raflinate fraction from a selective solvent extraction of a naphthenic mineral lubricating oil distillate fraction, with 20% to 50% by weight, based on the oil charge, of 103.5% to 105.5% fuming sulfuric acid, at a temperature between about 75 F. and F. for a period of about 10 minutes, thereafter immediately and before the separation of a sludge phase, intimately mixing the resulting reaction mixture with from about 25% to about 80% by weight of water, based on the acid used, selected to yield a separated acid sludge phase with an acidity of from about 50% to about 70%, Permitting the resulting admixture to stratify whereby only two layers are formed, an oil layer containing dissolved oilsoluble petroleum sulfonic acids and an acid sludge layer, and separating the layers.

3. A process for the production of an oil solution of oil-soluble petroleum sulfonic acids, which process comprises intimately contacting a mineral lubricating oil railinate fraction of naphthenic character, and having been obtained as a rafllnate fraction from a selective solvent extraction of a naphthenic lubricating oil distillate fraction, with 20% to 50% by weight, based on the oil charge, of 103.5% to 105.5% fuming sulfuric acid, at a temperature between about 75 F. and 150 F. for a period of about 10 minutes, thereafter immediately and before the separation of a sludge phase, intimately mixing the resulting reaction mixture with from about 25% to about 80% by weight of water, based on the acid used, selected to yield a separated acid sludge phase with an acidity of from about 50% to about 70%, permitting the resulting admixture to stratify whereby only two layers are formed, an oil layer containing dissolved oil-soluble petroleum sulfonic acids and an acid sludge layer, and separating the layers.

4. A process for the production of an oil solution of oil-soluble petroleum sulfonic acids, which process comprises intimately contacting a mineral lubricating oil rafilnate fraction of naphthenic character, having a viscosity at 100 F. of at least about 400 SSU, a viscosity index of from about 30 to about 60, a flash point of at least about 380 F., and having been obtained as a raflinate fraction from a selective solvent extraction of a naphthenic mineral lubricating oil distillate fraction, with to 50% by weight, based on the oil charge, of fuming sulfuric acid, at a temperature between about 75 F. and 150 F. for a period of not more than about 10 minutes, thereafter immediately and before the separation of a sludge phase, intimately mixing the resulting reaction mixture with from about to about 80% by weight of water, based on the acid used, selected to yield a separated acid sludge phase with an acidity of from about to about permitting the resulting admixture to stratify whereby only two layers are formed, an oil layer containing dissolved oil-soluble petroleum sulfonic acids and an acid sludge layer, and separating the layers.

5. A process for the production'of an oil solution of oil-soluble petroleum sulfonic acids, which process comprises intimately contacting a mineral lubricating oil raillnate fraction of naphthenic character, having a viscosity index of at least about 30, and a flash point of at least about 380 F. and having been obtained as a ramnate fraction from a selective solvent extraction of a naphthenic mineral lubricating oil distillate fraction, with from about 20% to about 50% by weight, based on the oil charge, of fuming sulfuric acid, at a temperature between about F. and If. for a period of not more than about 10 minutes, thereafter immediately and before the separation of a sludge phase, intimately mixing the resulting reaction mixture with sufllcient water to yield upon stratification a separated acid sludge phase with an acidity from about 50 to about 70%, permitting the resulting admixture to stratify whereby only two layers are formed, an oil layer containing dissolved oilsoluble petroleum sulfonic acids and an acid sludge layer, and separating the layers.

HENRY W. ANDERSON.

OTTO A. SAMSON.

AUGUSTUS W. CLARK.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,867,778 Terry et al July 19, 1932 2,036,469 Field Apr. 7, 1936 2,084,506 Rlosen June 22, 1937 2,252,957 Averill et al Aug. 13, 1941 2,285,390 Brandt June 9, 1942

Claims

1. A PROCESS FOR THE PRODUCTION OF AN OIL SOLUTION OF OIL-SOLUBLE PETROLEUM SULFONIC ACIDS DISSOLVED IN A HIGHLY REFINED LUBRICATING OIL FRACTION, WHICH PROCESS COMPRISES INTIMATELY CONTACTING A MINERAL LUBRICATING OIL RAFFINATE FRACTION OF NAPHTHENIC CHARACTER, HAVING A VISCOSITY AT 100* F. OF AT LEAST ABOUT 400 SSU, A VISCOSITY INDES OF FROM ABOUT 30 TO 60, A FLASH POINT OF AT LEAST ABOUT 380* F., AND HAVING BEEN OBGAINED AS RAFFINATE FRACTION FROM A SELECTIVE SOLVENT EXTRACTION OF A NAPTHENIC MINERAL LUBRICATING OIL DISTILLATE FRACTION, WITH 20% TO 50% BY WEIGHT, BASED ON THE OIL CHARGE, OF 105.5% FUMING SULFURIC ACID, AT A TEMPERATURE BETWEEN ABOUT 75* F. AND 150* F. FOR A PERIOD OF ABOUT 10 MINUTES, THEREAFTER IMMEDIATELY AND BEFORE THE SEPARATIO OF A SLUDGE PHASE, INTIMATELY MIXING THE RESULTING REACTION MIXTURE WITH FROM ABOUT 25% TO ABOUT 80% BY WEIGHT OF WATER, BASED ON THE ACID USED, SELECTED TO YIELD A SEPARATED ACID ON THE ACID USED, SELECTED ACIDITY OF FROM ABOUT 50% TO ABOUT 70%, PERMITTING THE RESULTING ADMIXTURE TO STRATIFY WHEREBY ONLY TWO LAYERS ARE FORMED, AN OIL LAYER CONTAINING DISSOLVED OIL-SOLUBLE PETROLEUM SULFONIC ACIDS AND AN ACID SLUDGE LAYER, AND SEPARATING THE LAYERS.