US2381708A - Sulphonation process - Google Patents

Description

Aug. 7, 1943. E. AMOTT SULPHONATIO-N PROCESS Filed April 24, 1942 NGN I N V EN T0 R. 59,91. Awa fr v ATTORNEY.

Patented Aug. 7, 1945 o UNITED t, STATES y 2,381,708y y SULPHONATION PROCESS Earl Amott, Long Beach, Calif., assigner to Unin v Oil Company of California, a'corporation of California Los Angeles, Calif., I

Application April` 24, 1942, Serial No. 4405389 `11 claims. (c1. 2160-504) This invention relates to the production of suiphonic acids and vto the conversion of the vsul-- phonic acids so metals.

sulphonic acids are conventionally produced by the reaction of fuming sulphuric acids on various types of mineral oil. One major source for the production of sulphonic acids is from the manufacture of white oils. In the production of white oils a suitable oil fraction, as for example, paraflinic type oil is treated at ordinary temperature with fuming sulphuric `acid. in suiiicient quantity to remove .all ofthe coloring matter present in the mineral oil. As a result yof this treatment two types of sulphonic acids are produced. The oil soluble type known as the mahogany acids are left for the most part in the treated oil and the sludge produced during the treatment contains thegreen acids. Most of the sulphonic acids and the sulphonic acid soaps offered on the market consist mainly of themahogany` acids in the form of their salts.

During the production of sulphonic vacid according to present day methods noparticular care is taken to prevent contamination -of the acids with materials, such as iron and lead, "which tends to lower the quality of these acids when used for certain purposes. Y Usually lthe treating vessel employed for contacting the minerall oil with the fumlng acid is made off metallic lead or steel. Furthermore, after the acidoil containing the mahogany acid is withdrawn from the lead or steelvessel no particular care is taken to prevent contacting this acid oil with transfer lines which are usually composed of these metals. As a resultthe free acid present in these acid oils dissolves a small amount of the lead and iron which in turn react to produce `lead and iron salts of sulphonic acid. l

I have discovered a method whereby sulphonic acids may be produced by a process which yields a product 4in the form of sulphonic acid salt which is substantially free from contaminants. I'have also discovered a process whereby sulphonic acids and sulphonic acid soaps can be prepared which contain a major proportion of both the green and mahogany sulphonic acids which distinguishes my product from the sulphonates usually sold on the market which contain for the most part the mahongany acids only.

In preparing the sulphonates according to my invention it is important rst to'select a lubricating oil fraction which will providea substantial yieldjof `the desired sulphonate. For this purpose certain lubricating oils of` both naphthenic and produced into salts of various paraflinic typehave been found acceptable and this apparently is true regardless of their viscosity. In general I find that mineral oil fractions which have been prepared by a moderate degree of renement give the best yield of sulphonic acids. This distinguishes thesev mineral oil fractions from those which have been highly frened by methods such as severe solventjtreatment and from the lightly acid treated mineral oils well known in the art several years ago. In

l' other words, I find it desirableV to employ an oil as the base stock for the production of the sulphonic acids which has been moderately treated rather than one which has received littlejor no treatment or one which has Vbeen severely treated. Oils which have been given little or no treatment 'producean inferior grade of A:sul-- phonic acids because these `oils contain fractions which are convertedinto resinous and sludgelike fbodies which `contaminate the nal product. Oils which have .been severely treated usuallydo not sulphonate very readily and, therefore, oil fractions of this type only produce very small yields of the sulphonated product. To illustrate, a lightly acid'refined naphthenic ltype oil, e. fg.,- Western base oil treated with ,twenty to thirty pounds of 98% `sulphuric acid per barrel is not desirable for the present purpose `since .prac-I tically alll of the acid used `for the productionof sulphonic acid is Iconsumed in producing sludge and the' quantity of `acceptable lsulpho'n'ates produced during the sulphonating step is negligible. Similarly; when a vhighly solvent treated type of lubricating oil,y e.- g., one of very highviscosity index produced by severe solvent extraction with benzol-sulfur ldioxide mixtures, or furfural, ;or dichlorethyl ether or nitrobenzenel is used, the sulphonatable materials of the required type apparently have been largely removed. Any attempt to `sulphonate such a severely treated Apetroleum fraction usually results in the .-:Eorma-A tionI of only a `small quantity of objectionable sludge. i f

` On the other hand, a naphthenic base oil which has been subjected to a light.' sulphuric acid treatment (twenty pounds of98% sulphuric acid per barrel of oil) and also to a moderate treatment with liquid sulphur dioxide so as toyield a lubricating oil of about 25 to 50 viscosity index is"an acceptable stock from which satisfactory yields of sulphonates can be produced by treatment with fuming sulphuric acid. Similarly, a mixed base oil moderately treated as by selective solvent extraction to yieldI a viscosity vindex of about is an acceptacle `sulphonatablev stock.

2 Furthermore, a Pennsylvania oil moderately treated to a viscosity index of 104 and having a viscosity gravity constant of 0.812 is a good sulphonatable stock. However, a medicinal white oil having a viscosity index of 72 and a viscosity gravity constant of 0.826 yields substantially no acceptable sulphonates upon treatment with fuming sulphuric acid. Thus neither viscosity index nor viscosity gravity constant nor, in fact, the type of oil appears to determine what constitutes a good sulphonatable stock. On the other hand, it appears to be the degree of renement which has here been designated as intermediate renement. Oils of S. A. E. 40 grade have been commonly used but lighter stock such as S. A. E. 20 and heavier stock, such as S. A. E. v

60 have been employed.

Specific oils which have been made are given below, the iirst six being acceptable as satisfactory sulphonatable stock, whereas the 'last five are of little or no practical value for the production of sulphonates.

ply some means of cooling the mixture undergoing neutralization to keep the temperature below this decomposition point. As a general rule I nd that at no time should the temperature during this neutralization step exceed substantially p My process may be more thoroughly understood by referring to the drawing.

Referring to the drawing, the oil to be sulphoriated is introduced into reactor I through line 2. Simultaneously fuming sulphuric acid is introduced into reactor I via line 3. The sulphuric acid and oil in reactor I are vigorously agitated .and after completion' of the sulphonation reaction the sulphonated product is removed from reactor I via line 4. The temperature employed in the reactor during the sulphonation reaction is ordinarily maintained at about 135 F., however, the temperature which may be employed in reactor I may be varied somewhat and in many cases it may be carried out through- -out the range of temperature between 100 F. and

ou type Treatment v.1. v. e. o Sfgrlgi Naphthenic: y

S. A. E. 40 25# H2SO4/bbl. followed by SO2 25 0.862 Highest.

S. A. E. 20 Same as for S. A. E. 40 25 0.862 Do. Parainic S. A. E. 40 Very moderate selective solvent 82 0.815 High. Pennsylvania S. A. E. 40 Usual (no selective solvent) 104 0.812 Do. Parain'c:

S. A. E. Moderate selective Solvent 90 0.804 Good.

S. A. E. Same as for S. A. E. 40 90 0.81 Do. Paraflinic S. A. E. 40 Heavy selective solvent 100 y0. 80 Bad. Perailin wax deoiled Normal 130 0.77 D0. Naphthenic S. A. E. 40 -20 Very bad. Mixed base S. A. E. l0 N -20 0.88 Do. Medicinal white oil 70 0.826 Zero.

In carrying out my process an oil having characteristics like one of the first six containedin the preceding table is rapidly agitated with concentrated sulphuric acid. By the term concentrated sulphuric acid I mean sulphuric acid which is of a strength lying between 100% sulphuric acid and pure sulphur trioxide. For practical purposes I iind that it is desirable to employ 40% fuming sulphuric acid since this gives the best yield of sulphonic acids.

After thorough agitation of the acid and the oil for a period between about ten minutes and sixty minutes the sulphonated product is Withdrawn from the agitator and is contacted immediately with a suitable alkali, such as for example,` calcium oxide, or a calcium hydroxide-water mixture, in an amount in excess of that required to neutralize all of the free sulphonic acids and free sulphuric acid present in the mixture. The neutralized mass is then allowed to settle for the separation `of `the excess alkali and the calcium sulphate which is formed by the reaction of the calcium oxide wi-th the free sulphuric acid present. This separation step may be facilitated by diluting the mixture either before or after the addition of the alkali with petroleum naphtha, liquid propane, liquid butane, liquid pentane or benzol. Furthermore, providing that the solid materials cannot be effectively separated byfsimple separating means the neutralized mixture may be centrifuged or filtered as a final-method of separating any solid matter present in the neutralized mass. l

During the neutralization' step heat is liberi ated and if care is not exercised Ithe product will rise to a temperature.v sufficiently-high to; cause a proportion of the sulphonic acids present'inthe mixture to be decomposed. In order to prevent this decomposition it is often necessary to'sup- 150 F. Likewise the time of contact between the acid and the oil in reactor I may vary considerably. For example, I have found that good sulphonated material can be produced by restricting the reaction time to a period or" ten mintues or by continuing this reaction time for a period of around sixty minutes.- In other words, I Wish it to be understood that the contact time between the acid and the oil in reactor I may vary considerably yand that I may employ a reaction period of from ten minutes to sixty minutes.

The strength of the acid employed in reactor I may also vary over a wide range. For example, I have found that sulphuric acid produces a satisfactory product and I have also found that pure sulphur trioxide may be employed. As --a matter of practice, however, I pre.- fer to use 40% fuming sulphuric acid since this material is easy to handle in the process and produces a very satisfactory product.

Ink carrying out the reaction in reactor I II have found that when I employ 40% fuming sulphuric acid that it is desirable to use an amount of acid in the reactor which will be equivalent to about 30% of the weight ofthe oil.

The sulphonated product withdrawn from reactor I through lines 4 and 24 and valve 23 is mixed with a diluent withdrawn from tank 5 via valve 9 and lines 8 and I0. This mixture of diluent and sulphonated product passes through agitator 26 where it is thoroughly mixed. The diluents which I may employ include such materials as petroleum naphtha and other light low boiling hydrocarbons, such as liquid pentane, butane, propane or mixtures thereof, or aromatic hydrocarbons such as benzol, toluol or xylene.l

. After thorough mixing of the diluent and sul-` phonated productI in mixer 26 and withdrawal through line 21 and valve 28, alkali withdrawn `iriiiii tank valve 'any aiidiinef'a (mixed with thediluentand ysulr'ihonateol product uct will ten'd to duce the calcium salt of I find that( it is'desirable Iris in agitator"32.It is important that the temperatu're` during this neutralization does n not exceed 170 be' found i that agportionyofthesulphonated proddecompose,l be employed 'tjmaintain a perature offthematerial in p simply to surround the a'gitatorwith a liquid vcooling medium, such Las cold. Awater or brine. Another meanfsjwhich could beemployedwould be relatively low temto permit 'the heater reaction between the-sulalkali to vaporize a phonated product and'the portion `of the low boilinghydrocarbon. diluent intoaocondensensnot shownwhere the hydrocarbon wouldbenliqueiedA andV refluxed back into the mixture.

y ,The vspeciic'i alkali ywitl'id'rawn` from container 29' for the" above' neutralization` depends upon what i ,product is'lto be obtainedV by the process.`

Forexample, if it isdesired to prosulphonic "acids "there is withdrawn; from container 29"`ordinary calcium oxide in ajqu'antityin excess `of that which .would be chemically required to neutralize' the acids Apresent in "the 'mixture flowing into 'agitator 32. `After thoroughagitation ofy the valkaline `material vand diluted, reaction mixture in agitatorl 32, the mixture then-f1owslntqsetiier l:asV via iine' s3 `and 'agitator34t .In`settle`r135 the vexcess alkaline material*y and sulphur'ic acid 4salts in aqueous solution settles out and is withdrawn from-settler via valve 36 and line 31. From the top of settler 35 the fully neutralized sulphonic acids in the form of sulphonates in diluted oil solution are withdrawn via line 38 and passed to 39. which may be either a centrifuge or afllter for the separation of any rema g solid alkaline material which has failed to settle out in settler 35. The solid material removed by the centrifuge or illter is discarded through line -40 and the clear diluted solution of sulphonates pass via line 4I into fractionator 42. Fractionator 42 is equipped with a coil 44 for the purpose of introducing sumcient heat into the diluted sulphonate solution to vaporize the diluent present which is removed via line 45 to condenser -46 where the diluent is liqueed and then passes via line 41 back to the diluent storage tank 5. From the bottom of fractionator 42 the sulphonate solution is withdrawn via line 43.

This process can be adapted for the production of a wide variety of sulphonates. For example, I may produce alkaline earth sulphonates by the use of calcium oxide, barium oxide, strontium oxide, or magnesium oxide, or I may produce alkali metal sulphonates by the use of sodium hydroxide, potassium hydroxide or lithium oxide. Obviously any other metallic sulphonate may be produced by the process which I have just described. For example, zinc, aluminum, cadmium, chromium, antimony, arsenic or tin.

In the foregoing description I have described the use of a diluent which is added to the sulphonated product withdrawn from reactor I from tank 5, valve 9 and lines 8 and I0. The amount of diluent which I employ at this point may vary. In many instances I ilnd that a one to one ratio '32. "One, means is..

r; `since above that ten'iperatiire it will Various means may line materialtoth `tator32. This is accomplished by closingvalves fluted'v with .diluent from' tohuse anywhere `from two to five volumes yof diluent to one volume of sulphonated 'product invlojrjder to obtain the desired degree of settling in settler 35. i,

In somecases i'thas been found that' itis more desirablet'o addlthe diluent to theyslllphonated material subsequent tothe Vaddition of the 'alkae sulphonated product in agi- 23and y9l and 'opening valve `25. Bythis arrangementthe sulphoria'ted material in line 4 passes via lValve 25 into agitator 32 where'itis converted linto `the sulphoiate salt by admixture with the alkaline passes into settler 35k wherelth'e excess'alkalinc material is withdrawn,""as explained above', through valve 36 and line-31. In'many instances it is c 'ir'ni'naterialv` Whether'the diluent isv introduced either before'orf alfterthe sulphonated product is contacted withwthe 'alkaline materialijin agitatorA 32. HowevenfI have foundin some cases that the degreeofsettling inv settler 35 is "greatly influencedfby the `point of introduction of the dllle'ntj i i ;I

vcomrxiercial varieties' of sulphonic acid salts now being oiTered on the market. The meth-ods which I have described for the production of sulphonic acids reduces the tendency of the acidic material Withdrawn from reactor l from being contaminated with materials which would normally be dissolved by this material. In other words, the product which is Withdrawn from reactor l contains a substantial quantity of free acid which normally attacks the walls of reactor I as well as the transfer lines and results in contamination of the product. However, if the material withdrawn from reactor I through line 4 is immediately neutralized for the removal of any free acid from the sphere of activity it is obvious that a product will be obtained which is less contamim nated with impurities, such as iron sulphonates, than would be obtained provided this neutralization step were eliminated. In carrying out the process it is essential that the sulphonated product withdrawn from reactor l be passed without substantial delay to the neutralization step in 32 in order to prevent the possibility of contamination.

I claim:

1. A process for the production .of oil soluble mixtures containing substantial amounts of metal salts of both mahogany sulphonic acids and green sulphonic acids dissolved in lubricating oil which comprises contacting a mineral lubriof diluent to sulphonated product is suicient to obtain theY desired degree of settling in settler 35. However, in cases where it is desired to increase the rate of settling and the degree of settling it may be found necessary to increase the quantity of diluent employed. For example, in some cases of both the mahogany acids andthe green acids in theunreacted'oil.

2. A process according to claim 1l inwhich the solution' of metal sulphonates is settled to separate therefrom undissolved inorganic compounds. l

3. A. process for' the production of. oil soluble mixtures containing substantial amounts of. metal salts of both mahogany sulphonic acids and green sulphonic acids dissolvedv in lubricating oil which comprises treating a mineral lubricating oil `with concentrated sulphuric acid at. a temperature between about 10'0" F. and 150 F. and thereby forming a mixture of sludge containing. green acids and. unreactedi oil containing mahogany acids, andv immediately neutralizing said green and mahogany acids with an alkaline. compound of the desired metal without-separation of. sludge thereby causing themetal sulphonatesof both the green andv mahogany acids to dissolve in the unreactedl oil.

4. A process according to claim 3 inwhich. a low boiling hydrocarbon diluent is added tothe reaction product before the addition of the alkaline compound.

5. A process' according; low boiling hydrocarbon diluent is added to the solution of the` metal sulphonates and the. thus diluted solution is settled for the separation of undissolved inorganic compounds. v

6. A process according to. claim temperature is maintained below about 170 during ther addition of the alkaline compound.

7. A processfor the production of.- lubricating oil solutions containing substantial amounts of alkaline. earth metal salts ofi both mahoganyv sulto claim. 3 in which a.

3 in which the phonicwacids. and greensulphonic acids which comprises contacting. ahlubricating oil of an. -intermediate, degree of' rennement with .sulphuric acid havingl concentration greater than '100%y at a temperature lbetiiteerr about 100,F..and-1'50 F` thereby `rco'nveijtiri,gaportionoi' y'said oil to'. a mix- `-ture containing oil solublel mahogany sulphonic acids; oil ,insoluble vgreenjsulphoni'c acids and unreactedlfoil; neutralizing the, freelacidity of v the entire. reaction product by the additionthereton of an ,excess fofA alkaline 'compound of, al.-

kaline earth metal', thereby 'converting'. both the mahogany acids andthe green'acids toftheir a1- lralineearth metal sulphonates and dissolying theseI sulphonates. ,in unreacted oil;.fadding a low boiling .hydrocarbon Ydiluent I,to the saill'ubrieating oil solutioniofmetal su1phonats;and settlngthe thus diluted solution for separationof undissolved inorganic compounds..

8. .A' process accordingt to claim "Tin .the alkaline earth, metal is calcium.

91. A process according. to. claim-fl .stock is'ja napht'henic lubricating nil'ofl interme- .diatejrefinement l `l0. Aprocessaccording lzinyvhichfthe amount of concentratedsulphuric acid fernployed t] of. oil..treated, vand is smaller. than' theamo 'the .temperatureduring sulphonationis maintained below .ahora 15o n..

11.V A processaccording'. tof claim ..'l in which the. temperature main fined below about 170? F. during, the. .neutrali`zation byevaporationbt dhlent.. L.: y... f y

.1 EARL A-Morr'r.

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