April 7, 1942. H. C. PAULSEN 2,278,665 REFINING PETROLEUM OIL Filled Sept. 14, l939

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Patented Apr. 7, 1942 2,278,665 UNITED STATES PATENT OFFICE 2,278,665 REFINING PETROLEUMOILs Henry C. Paulsen, Elizabeth, N. J., assignor to Standard Oil Development Company, a corpo ration of Delaware Application September 14, 1939, Serial No. 294,800 5 Claims. (CI. 196-29) This invention relates to the refining of pe troleum oils. The invention is particularly con prove its anti-knocking characteristics, and to Cerned with refining a gasoline and like prod improve its Susceptibility for knock-suppressing, ucts, and especially relates to a process and ap agentS, as for example, tetraethyl lead. paratus for treating sulfur-containing oils with Various Suggestions have been made for over Sodium plumbite or analogous lead compounds coming these inherent difficulties resulting from for the purpose of removing sulfur compounds the addition of free sulfur. The suggested meth of the character which render the petroleum ods are more or less cumbersome and not en oil sour. The invention is more particularly . . tirely satisfactory from a commercial standpoint. directed to an improvement in the so-called For example, Varia.us electrolytic methods have "doctor Sweetening operation' by which higher 10. been tried in order to accurately determine the quality petroleum products are secured and in amount of sulfur necessary to just quantitatively which material economies in the process are ef precipitate the lead. These methods are not en fected. In accordance with the present inven tirely practical since the reaction when using the tion, the lead mercaptides are converted to di quantitative amount of sulfur is very slow in sulfides and lead oxide by utilizing hydrogen 5 reaching completion which decreases the: peroxide in a novel procedure which materially through-puts and equipment capacities. v. improves the operation. I have now discovered a process by which sour oils may be readily treated in the usual manner Mineral oil distillates, as for example, pe With an alkaline solution of sodium plumbite or troleum oil distillates boiling in the kerosene and 20 doctor Solution and the resulting soluble lead motor fuel boiling range, contain certain sulfur mercaptides completely converted in an efficient compounds which impart disagreeable odors to manner. In accordance with my invention, these the oil. Various methods have been employed, Soluble lead mercaptides are converted to lead for the removal of these compounds or for the oxide and lead sulfide by the addition of hy. conversion of these disagreeable sulfur com drogen peroxide to the oil containing litharge, pounds to innocuous materials. However, these thus insuring that the sulfur content of the oil compounds are usually removed by agitating the Will not be increased and that no undesirable oils with an alkaline Solution of an alkali metal Sulfur polymers will be formed. The process of plumbite such as sodium plumbite which is pre my invention may be demonstrated by the foll pared by dissolving lead oxide in an excess of 30 lowing reactions: Sodium hydroxide. When the petroleum oil and plumbite Solution are mixed, a chemical reaction occurs resulting in the conversion of mercaptains to Corresponding lead mercaptides. These mer captides are then decomposed, usually by the 35 addition of free sulfur, resulting in the lead be My invention necessarily results in the pro ing precipitated as an insoluble lead sulfide and duction of a higher quality oil completely free of in the formation of odorless disulfide compounds. corrosive sulfur and having high anti-knocking This operation known as 'SWeetening' may be characteristics as well as having a high suscepti Summarized by the following reactions: 40 bility for knock suppressing agents. Possible re running of the treated oil for the removal of un desirable Sulfur polymers is eliminated. Fur thermore, my process eliminates the regenera tion of doctor Solution stage since the lead from This operation is not entirely satisfactory since 45 the hydrogen peroxide treated oil Containing in Order to insure complete removal of the Sol litharge is removed as lead mono-oxide by wash. uble lead compounds from the oil, it is necessary ing with sodium hydroxide and used as fresh to add a sufficient amount of sulfur, which oft doctor Solution. - times results in the use of an excess of elementary. The process of my invention may be readily Sulfur. The excess sulfur dissolved in the gaso-, 50 understood by reference to the attached drawing line is very undesirable since it impairs the illustrating one modification of the same. For quality of the gasoline with respect to corrosive purposes of description, the feed oil is taken to neSS and anti-knocking properties as measured: be a mercaptain containing petroleum naphtha. by a lower octane number. Furthermore, in the boiling in the motor fuel boiling range. The usual doctor Sweetening operation, certain pe Sour gasoline containing mercaptains is introl. troleum oils upon the addition of free sulfur, duced into the Sweetening system by means of particularly if an excess be used, will form objec feed line . A solution of sodium plumbite is tionable polysulfide compounds. If this situa introduced into the sweetening system by means tion occurs it is necessary to redistill the motor of line, and is mixed with the sour gasoline in 60 contacting pump 2. The mixture in an initial fuel in order to reduce its corrosiveness, to im stage passes through valve 3, mixer 3 andline 2. 2,278,665 into settling drum G, wherein separation of the peroxide concentration of from 5 to 10%. When spent doctor solution from the leaded gasoline using aqueous solutions of peroxides of these containing lead mercaptides occurs. In the concentrations, it is sufficient to contact the lead initial stage the mercaptain compounds con mercaptide containing oil with from about 2 to tained in the oil are converted to oil-soluble lead 5 10% of aqueous, peroxide solution. mercaptides and the spent doctor solution layer The process of the present invention is not segregated from the leaded oil. i.he leaded gasor to be limited by any theory or mode of operation, line containing lead mercaptides is withdrawn but only in and by the following claims in which from settling drum 6 by means of line and in it is desired to claim all novelty in so far as the a secondary stage mixed with hydrogen per 10 prior art permits. oxide which is introduced by means of line. I claim: 2 and contacting pump 9, the mixture with 1. Process for... converting nercaptain com drawn from contacting pump. 0, by means of, pounds contained in the petroleum oil to di line f l and introduced into Settling dium 3, sulfide compounds, comprising contacting said wherein separation of the spent aqueous. hydro-. 1: petroleum oil in an initial stage with a Sodium gen peroxide solution from the gasoline contain plumbite solution under conditions to convert the ing suspended lead oxide occurs. In the second mercaptain compounds to corresponding soluble ary stage, the lead mercaptides are reacted with lead mercaptides, separating the spent Sodium hydrogen peroxide under conditions to form al plumbite solution from the treated oil containing oil layer containing lead oxide and a spent the soluble lead mercaptides, passing the treated aqueous solution of hydrogen peroxide. The oil fraction into a secondary stage and contacting spent aqueous peroxide solution is withdrawn the same in said secondary stage with hydrogen from settling drum 3 by means of a liquid level peroxide under conditions to convert the lead control valve 5 and line 6. The oil containing mercaptides to lead oxide and disulfide com suspended lead oxide is withdrawn from settling, pounds, whereby a water layer is formed in said drum 3...by means of line f4, and in a tertiary secondary stage, separating the water from the stage contacted with spent doctor solution from treated oil, passing the treated oil containing, sol said initial stage under conditions whereby a uble lead disulfides and the lead oxide to alter treated substantially lead-free oil phase con tiary stage and contacting the treated oil in said taining disulfides and a regenerated doctor solu 30. tertiary stage with the spent alkali metal tion phase are formed. The oil withdrawn by plumbite solution removed from said initial stage means of line 4 is passed-through contacting whereby the lead oxide is completely, removed pump 7 wherein it is mixed with spent doctor from said treated oil. solution withdrawn from settler 6 by means of 2. Process as defined by claim.1, in which said line 9. This mixture is withdrawn from con alkali metal plumbite solution is a sodium tacting pump 1 by means of line f8 and intro plumbite solution. duced into settling drum 9. The regenerated 3. Process as defined by claim 1, in which the doctor Solution separates from the sweetened spent alkali metal plumbite solution containing gasoline in settling drum 9. and is withdrawn the lead oxide is removed from said tertiary stage from settling drum 9 through valve 2; and then and recycled to said initial stage. passed into doctor solution storage 29, by means, 4. Continuous process for converting mercap of line 22. The doctor solution is withdrawn from tan compounds contained in a petroleum oil to doctor solution storage 29 by means of line 4 and disulfide compounds which comprises passing mixed with fresh unsweetened gasoline in con said oil continuously through an initial, a sec tacting pump 2. Fresh doctor solution may be ondary, and a tertiary stage, contacting said oil, introduced in the system by means of line 32. in said initial stage with a sodium plumbite solu The Sweetened gasoline substantially free of lead tion under conditions to convert the mercaptain oxide is withdrawn from settling drum. (9 by compounds to corresponding lead mercaptides, means of line 20 and passed into mixing column separating the spent alkali metal plumbite solu 24 along with water which is introduced by means tion and the treated oil and withdrawing the said of line 23. The water-gasoline mixture is Spent alkali metal plumbite solution and the said withdrawn from mixing column 24 by means of, oil from said initial stage, contacting the treated line 25 and passed into settling drum 26 in which oil removed from said initial stage in said sec the added water is separated from the sweetened, ondary stage with hydrogen peroxide, under con washed gasoline. The water is withdrawn from ditions to convert the lead mercaptides to lead Settling drum 26 by means of a liquid level con oxide and disulfide compounds, whereby a water trol valve 27 and line 28, while the finished sweet layer is formed, separating the water.layer from ened gasoline is withdrawn from setting drum the treated oil containing-lead oxide and with 26 by means of line 30 and passed to finished drawing the said water layer and the said treated gasoline storage. Liquid level control valves, 8, 60 oil containing lead oxide from said secondary 5, 21 and 27 control the level of the heavier. stage, contacting the treated oil withdrawn from layers which are withdrawn from the bottom of said secondary stage in said tertiary stage with the respective settlers. It is to be understood the Spent alkali metal plumbite solution with that any desirable mixing, heating, cooling, or drawn from the initial stage, whereby a treated distributing means may be employed. oilalkali layer metal completely plumbite free solution of lead oxidelayer andcontaining. a spent The process of the present invention may the lead oxide are formed, separating the layers widely vary. Although elevated temperatures and and Withdrawing the said treated oil layer and pressures may be employed, it is preferred to the said spent alkali metal plumbite solution from contact the gasoline with the doctor solution at Said tertiary zone...... ordinary temperatures and pressures. The 5. Process as defined by claim 4, in which the amount of hydrogen peroxide introduced should Spent alkali metal plumbite solution containing be sufficient to completely convert all soluble lead the lead oxide is removed from said tertiary compounds to lead oxides. In general, it is pre stage and recycled to said initial stage. - ferred20% peroxide to use concentration,aqueous peroxide preferably solutions having of 1 to a 75 HENRY. C. PAULSEN.