Патент USA US2405872код для вставки
2,45,872 Patented Aug. 13, 1946 UNITED STTES PATENT OFFICE 2,405,872 METHOD FOR REMOVING WEAKLY ACIDIC SULPHUR COMPOUNDS FROM HYDRO CARBON OIL George W. Ayers, Chicago, and Daniel M. Barton, Elmwood Park, 111., assignors to The Pure Oil Company, Chicago, Ill., a corporation of Ohio No Drawing. Application June 21, 1943, Serial No. 491,668 8 Claims. (01. 196—30) 2 1 a method for removing mercaptans from petrole um distillates. for removing weakly acidic bodies from water A further object of the invention is to provide immiscible organic fluids and is more particularly a method for removing from high-boiling tar concerned. with a method and reagent for re acids, constituents which are objectionable when moving mercaptans from petroleum oils, tar acids are used as solubility promoters in al In Patent No, 2,316,966 there is disclosed and kali solutions to remove weakly acidic bodies such claimed a method for removing acidic bodies from as mercaptans from hydrocarbon or other sub water-immiscible ?uids by contacting such fluids stantially neutral water-immisible ?uids. with aqueous alkali solutions containing the reac A still further object of the invention is to tion product of an alkali and high-boiling tar 10 provide an improved solubility promoter for use We have found that high-boiling acids ' acids. in extracting weakly acidic bodies from organic may cause difficulties when used in the extraction water-immiscible ?uids. of mercaptans from gasoline and other petroleum Other objects of the invention will appear from distillates. These tar acids contain substances which impart to the gasoline or other oil which 15 the following description: In the low-temperature, by-product, destruc~ is treated therewith, objectionable color and tive distillation of coal, there is ordinarily con cloudiness. Moreover, in certain instances, al tained a dark liquid called coal tar which upon kali solutions containing these tar acids become distilaltion produces oils of different boiling very viscous and even solidify at temperatures of 40° F. or lower, with the result that emulsion dif 20 ranges and a residual pitch. It is common prac tice in the coal-tar industry to distill coal-tar ficulties are encountered during use of such solu This invention relates to a method and reagent into several fractions; one being light oil, boiling tions. Gasoline treated with alkali solutions con taining high-boiling tar acids may acquire an un up to about 200° 6., another known as middle oil organic sulphur compounds.” such as, phenol, cresols and one or more xylenols. boiling from about 200 to 250° 0., a third frac pleasant odor. A further di?iculty which is some times experienced is the interference with the 25 tion known as heavy oil boiling from about 250 to 300° C., and a fourth fraction known as an analytical determination of the mercaptan sul thracene oil boiling from about 300 to 350° C. It phur content of the treated gasoline. Di?iculty is is common practice to treat fractions with aque~ experienced in determining the end point during ous alkali solutions to remove therefrom the acid the titration of the gasoline using the silver ni trate-ammonium thiocyanate titration method 30 ic substances contained therein. The resulting aqueous alkali solution is neutralized with acid disclosed in the May 13, 1941, analytical edition to recover the acidic substances extracted from of “Industrial and Engineering Chemistry,” vol the various oil fractions. The acidic substances ume 13, page 298 in an article by Bell and Agruss are then fractionated to obtain various phenols entitled, “Analytical procedure for mixtures of In the fractionation, the separation is made be We have discovered that all of the foregoing tween those constituents boiling below and above diihculties can be eliminated if the high-boiling approximately 220° C. The residual liquid from tar acids are treated to eliminate therefrom, those the fractionation of the tar acids is the material constituents soluble in water which impart to the herein referred to as “high-boiling tar acids” aqueous solution a greenish-black color in the 40 and shows the following distillation analysis: presence of substantially acid-free ferric chloride. “ °C. It is not certain whether or not the substances Initial boiling point ____________________ __ 100 which cause the dimculty are those substances which turn aqueous solutions a greenish-black 45 5% off ________________________________ __ 220 10% off _______________________________ __ 229 upon addition of ferric chloride, but if those sub stances which do turn the solution a greenish black are removed from the tar acids, the remain ing tar acids cause no di?iculty when used in alkali solution to treat petroleum oils. 50 An object of the invention is to provide an improved method for removing weakly acidic bodies from otherwise neutral organic water-im miscible ?uids. Another object of the invention is to provide 55 20% 30% 40% 50% 60% 70% 80% 90% off off off off off off off off _______________________________ __ _______________________________ __ _______________________________ __ __ ___ _______________________________ __ _______________________________ __ _______________________________ __ ___ ___ 95% off ____ Dry point ____ __ 247 261 270 280 296 312 326 350 375 _____ __ 400 2,405,872 3 4 A solution was prepared, using high-boiling tar acids made in the manner just set forth and ob tained from the Reilly Tar & Chemical Corpora . A sample of the same gasoline was treated with 7.6% by volume of the solution containing 20% by weight of soduim hydroxide, 20% by weight of water-washed high-boiling tar acids and 60% by tion by mixing together 20% dry sodium hydrox ide, 20% tar acids and 60% of water, by weight. weight of water in a counter-current tower. The resulting solution was not entirely homoge mercaptan sulphur of the‘ gasoline was lowered neous, but contained liquid or solid material which had a shiny appearance. 300 cc. of Dubbs cracked gasoline from Texas crude oil was agi tated with ‘7% by volume of the'solution and the 10 from 0.096% to 0.005. A comparison of the oc tane numbers and lead susceptibilities of the gas oline before and after treatment is given in the The following table: resulting gasoline Was colored yellow-brown. The treating solution continued toiimpart the yellow-brown color to successive batches of gas oline. In addition, the gasoline was cloudy. An Table Octane numbers attempt was made to determine the mercaptan 15 Without sulphur content by the silver nitrate-ammonium thiocyanate titration method, but considerable difficulty was experienced in determining the end point of the titration. Moreover, emulsion di?i T. E. L. T. E. L. '1‘. E. L. T. E. L. T. E. 0.5 cc. 1.0 cc. 2.0 cc. 3.0 cc I Untreat ed culties were encountered when an attempt was 20 gasoline. .__Treated gaso 68. 6 71.0 72.0 73. 4 75.0 line _______ _ _ 68. 8 71. 6 73. 5 75. 3 77. 0 made to counter-currently contact gasoline with These ?gures show a notable increase in lead susceptibility of the treated over the untreated gasoline. In order to make a '72 octane gaso ing together 20% of NaOH, 20% of water-washed, 25 line from the treated sample, only 0.6 cc. of tet raethyl lead was required, thereby effecting a high-boiling tar acids and 60% of water by the treating solution in a counter-current con tact tower. Another treating solution was prepared by mix weight. The water washing of the high-boiling tar acids was carried out by vigorously agitating high-boiling tar acids with an equal volume of boiling water for one-half hour and drawing oif the upper aqueous layer and repeating the wash ing step with an equal volume of fresh ‘boiling water three additional times. Each aqueous layer was tested by adding thereto a few drops of freshly prepared aqueous ferric chloride solution containing approximately 2% of'ferric chloride. The aqueous layer from the ?rst two washings saving of 40% in the quantity of tetraethyl lead over that necessary to vbring the'untreated sam ple up to 72 octane. , It should be understood that water-washing of the high~boiling tar acids need not be done with boiling water, nor is it necessary to use the ratio of acids to water or the particular number of washes herein specified. Water of lower tem perature may be used, but will require a larger amount of washing or a longer washing period to remove the objectionable substances from the gave a greenish-black color upon addition of the tar acid. Larger ratios of water to tar acids will reduce the number of washings. We prefer wa ferric chloride while the aqueous layer from the last two washes gave a violet-black color with 40 ter approaching the boiling point in temperature because of the viscous character of the high the addition of the ferric chloride. The concen boiling tar acids. If it is desired to use cold wa tration or amount of ferricv chloride solution used in the test is not important since the color re ter or water which is only slightly warm, it may action occurs in " the presence of a very small be expedient to dilute the tar acids with an inert water-immiscible fluid to lower the Viscosity, and amount of the ferric chloride. It is important that the ferric, chloride be substantially acid to remove the diluent before adding the tar acids free since acid interferes with the color change. Therefore, freshly prepared ferric chloride solu tion should be used. The alkali solution prepared by using the wa ter-washed tar acids was homogeneous even when cooled to 40° F. A sample of the same Dubbs cracked gasoline from Texas crude was treated with 7% by volume of the aforesaid alkali solu tion containing the washed high-boiling tar acids. The treated gasoline was only slightly colored, to the alkali solution. 1 The extent of water-washing in any case, is determined by testing the wash water with ferric chloride solution. When the color of the washed Water upon addition of ferric chloride, changes from greenish-black to violet-black, the washing is sufficient. no objectionablerforeign odor, caused no trou blesome emulsoin in the treating step and could Our invention is not limited to the particular manner for removing the objectionable sub stances from high-boiling tar acids, but it is in tended to include the use of high-boiling tar acids as solubility promoters where tar acids are free of substances which dissolve in Water to give a be titrated for mercaptan sulphur with ease. 60 greenish-black color on addition to the water of contained no appreciable'haze or cloudiness, had There was no difference in the amount of mer captan sulphur removed by the solution contain ing the unwashed and the washed high-boiling tar acids. The mercaptan sulphur content of the gasoline was lowered from 0.096% to 0.0231% in a single treatment with 7% by volume of the treating solution. A treating solution containing 20% by volume of solid sodium hydroxide, 20% of water washevd tar acids, 5% of commercial cresol and 55 %'of water by weight, when contacted’ with the same gasoline in an amount of 7% by volume, lowered the mercaptan sulphur content to 0.01'76%_and caused no objectionable odor, color, haze or emulsion. ferric chloride. Although for purposes of demonstrating the invention we used a solution made by mixing to gether 20% of sodium hydroxide, 20% of water washed high-boiling tar acids and water, the composition of the solution may vary within wide limits. In order to obtain appreciable removal of mercaptans from hydrocarbon oils the treat ing solution should contain at least 5% by weight of free alkali metal hydroxide, i. e. alkali metal hydroxide over and above that necessary to re act with other constituents of the solution, and at least 5% by weight of high-boiling tar acids, but preferably in excess of 10%. Either sodium 75 or potassium hydroxide or a mixture thereof may 2,405,872 5 be used as the alkali metal hydroxide. 6 Care should be exercised to keep the free alkali hy constituents which in ‘aqueous solution turn greenish-black in the presence of ferric chloride droxide concentration of the solution below the point at which the solution becomes so viscous as to cause emulsion dif?culties during the treat to enhance the ability of said solution to extract said sulphur compounds from the hydrocarbon oil. 3. Method in accordance with claim 1 in which the aqueous solution contains at least 10% by droxide concentrations up to 25% by weight are weight of high-boiling tar acids in the form of satisfactory. The washed tar acids may be added their reaction products with alkali. to the solution as such or in the form of alkali 10 4. The method of removing mercaptans from gasoline which comprises contacting the gasoline metal salts. The tar acid content of the solu tion may extend up to the maximum amount with an aqueous solution made by mixing to gether approximately 20 parts by weight of al which is compatible with the solution and will kali metal hydroxide, 20 parts by weight of high vary with the alkali concentration of the solu tion. Other solubility promoters such as phenols, 15 boiling tar acids which have been water washed low boiling fatty acids and naphthenic acids may to remove therefrom objectionable gasoline-sol uble color-imparting‘bo'dies and sufficient water be usedwas components of the treating'solution. Treatment of gasoline and other hydrocarbon to keep the alkali metal hydroxide and tar acids in solution. distillates by means af alkali solutions contain 5. The method of improving high-boiling tar ing tar acids prepared in accordance with our 20 invention may take place at ordinary atmospheric acids for use as solubility promoters in alkali temperature and preferably within the range of solutions which consists in washing said tar approximately 40-100” F. The ratio of treat acids with at least two volumes of water until the wash water changes from greenish-black to ing solution to oil undergoing treatment will de pend on the nature and amount of acidic bodies 25 violet-black color upon addition of ferric chlo ride. contained in the oils, but in general, a ratio of 5 6. The method of improving high-boiling tar to 20% of treating solution by volume based on acids, for use as solubility promoters in alkali the oil undergoing treatment can be used with solutions which consists in washing said acids good results. The treating solution can be re generated by boiling or by stripping the absorbed 30 with at least two volumes of hot water until the wash water no longer turns greenish-black upon acidic constituents therefrom by means of steam at temperatures of approximately 220-250" F. additionof ferric chloride. 7. The method of removing from high-boiling It is claimed: tar acids substances which discolor gasoline 1. The method of removing weakly acidic sul phur compounds from hydrocarbon oil which 35 when contacted with alkali solutions containing said tar acids which consists in washing said tar comprises contacting said oil with aqueous solu acids with at least four volumes of boiling water, tion containing at least 5% by weight of free the amount of water being su?icient to remove alkali metal hydroxide and a su?icient amount from said tar acids substances which turn water of the soluble reaction products of an alkali and high-boiling tar acids which have been freed 40 containing them greenish-black upon addition of ferric chloride. by water washing of constituents which react with ferric chloride in aqueous solution to im 8. Method in accordance with claim 1 in which part thereto a greenish-black coloration to en the aqueous solution contains not less than 10% by weight of free alkali metal hydroxide but less hance the ability of said solution to extract said ing steps. Free sodium hydroxide concentrations up to 20% by weight and free potassium hy sulphur compounds from the hydrocarbon oil. 2. The method of removing weakly acidic sul phur compounds from hydrocarbon oil which comprises contacting said oil with aqueous so lution containing at least 5% by weight of free " than that amount which causes the solution to be so viscous as to cause emulsion difficulties when mixed with the hydrocarbon oil, and in excess of 10% by weight of high boiling tar acids in the form of reaction products with the alkali alkali metal hydroxide and a su?icient amount 50 metal hydroxide. of the soluble reaction products of an alkali and higher boiling tar acids which have been washed sufficiently with water to remove therefrom those GEORGE W. AYERS. DANIEL M. BARTON. " " "