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2,411,959 Patented Dec. 3, 1946 UNITED STATES‘. PATENT 1 OFFICE 2,411,959 METHOD OF PURIFYING PETROLEUM PRODUCTS ' Melvin A. Dietrich, Claymont, Dei., and chimes J. Pedersen, Penna Grove, N. J .,‘ assignors to E. I. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No ‘Drawing. Original application November 25, 1943, Serial No. 511,736. Divided and this ap plication January 18, 1946, Serial No. 642,134v _ 6 Claims. 101. 196-30) 1 2 , This invention relates to methods for purifying organic substances and particularly to purifying water-immiscible organic substances which are contaminated with catalytically active metal compounds. ' . - > This is a division of our copending applica . stance being treated. Still other objects will ap pear hereinafter. ' - " The above and other objects may be accom plished in accordance with our invention which comprises washing the contaminated water-im miscible organic substances in the liquid state with a dilute aqueous solution of a compound of tion Serial No. 511,736 ?led November 25, 1943. the class of organic thiols containing from 1 to 10 Many organic products tend to deteriorate on carbon atoms and at least 1 water-solubilizing aging, especially when exposed to free contact with the atmosphere. This deterioration gener 10 group and water-soluble salts of such thiols. We have found that, by this procedure, we are able ally involves autooxidation due to thereaction to very e?ectively remove from the organic sub of the organic substances with molecular oxygen. stances, dissolved catalytically active compounds It has been proposed to overcome this di?‘lculty by of heavy metals of the group of copper, iron, co incorporating in the organic substances various compounds which inhibit or retard the deteriora 15 balt, manganese and vanadium. This was par ticularly unexpected since the thiols and their tion and which are generally known as anti-v water-soluble salts are generally more soluble in oxidants. Frequently, such organic substances water than in the organic substances being become contaminated with catalytically active treated. It was especially surprising to ?nd that compounds of heavy metals, such as copper, iron, cobalt, manganese and vanadium, which speed the 20 such thiols and their water-soluble salts are far superior to sodium sul?de when employed in the aging of the organic substances and the oxida > same manner and remove the catalytically active tion of the antioxidants themselves, thereby ren metal compounds from the organic substances dering the stabilization with antioxidants more much more completely. di?lcult. - An example of this is in the copper sweetening of gasoline wherein traces of copper 25 The-organic substances, which may be treated in accordance with our invention, are those or frequently remain in the gasoline and greatly shorten its useful life. It has been proposed to overcome. the effect of such metals by adding, to the organic substances contaminated there with, a metal deactivator which reacts with the 30 ' metal and renders it ‘catalytically inactive. . Methods have also been proposed for removing ganic substances which are immiscible with water and which are liquid at ordinary temperatures or which may become liquid-at higher temperatures up to about 100° C. Our invention is particularly , applicable to the treatment of petroleum products, such. as gasoline, fuel oil, lubricating oils and the like. Our invention is especially directed to the puri?cation of copper sweetened cracked gasoline. nated organic substances. A common and well Our process may be employed for removing dis known example of this is the washing of copper 35 solved catalytically active compounds of heavy sweetened gasoline with an aqueous solution of metals, such as copper, iron, cobalt, manganese sodium sul?de for removing copper remaining in and vanadium. It is particularly e?ective for re the gasoline. _ moving dissolved catalytically active compounds It is an object of the present invention to pro vide a new and, improved'method of purifying 40 of copper from organic substances and particu larly. from petroleum products, such as copper water-immiscible organic substances contami sweetened cracked gasoline, ' nated with dissolved‘ catalytically active com We have found that organic thiols, containing pounds of the group of copper, iron, cobalt, man from 1 to 10 carbon atoms and at least 1 solubil ganese and vanadium. A more particular object is to provide a new and improved process for re 45 izing group and the water-soluble salts of such thiols, when employed inan aqueous solution, are moving soluble copper compounds from'cracked very e?ective for removing catalyticaliy active gasoline and especially from copper sweetened compounds of heavy metals from water-immisci gasoline. Another object is to provide such a ble organic substances contaminated therewith. method wherein the organic substance is washed with an aqueous solution of a compound which 50 These compounds may be represented by the for is unusually effective for the purpose and is much more e?ective than sodium sul?de. A still fur ther object is to provide such a method, employ wherein M represents. hydrogen, ammonium or ing aqueous solutions of compounds which are alkali metal and R represents a pclyvalent or more soluble in water than in the organic sub catalytically active metals from such contami mula - . 3 2,411,950 ~ ganic radical containing from 1 to 10 carbon 4 liter separatory tunnel. The gasoline was sepa rated, dried, and ?ltered by gravity through atoms and 1 or more water-solubilizing groups. Representative water-solubilizing groups are paper. The induction periods or untreated and treated samples 0! gasoline and their response to a, commercial antioxidant (p-(n-butylamino) - phenol, abbreviated BuPAP) were determined by the accelerated method described in J. ‘LE. C. 25 (397 (1933)). This method consists in heatlns wherein M represents hydrogen, ammonium or alkali metal. irrererably, the mums and their salts are more soluble in water than in the or 100 cc. of gasoline at 100° C. in a l-llter Pyrex ganic substahce- to be purmed. water-soluble 10 ?ask containing pure oxygen. The internal pres organic tniols and water-soluble salts tnereor' are sure is observed every 10 minutes by meansoi a manometer attached to the system. The elapsed time. from the start of the test until thegasoline those which are soluble in water to the extent of at least 0.1% at the temperature at which the treatment is to take place. The term “organic thiols" will be understood to include compounds, such as thlourea, thiosemicarbaziue and .N-gua begins to absorb oxygen at the rate of 10 cc. per 10 minutes or higher, as shown by the fall in in ternal pressure, is taken as the induction period. It has been found that the induction period, ob nylthiourea, which. as origmahy written, do not appear to have a mercapto group in the structur tained by this method, although greatly short a1 iormulae, but which exist in tautomeric forms. ened, is a fairly accurate measure of the relative stability of gasoline under normal storage condi one of which contains a mercapto group. For ex ample, thiourea exists in the Iohowing 2 forms: tions. . The results of these tests are shown in Tables I and II. " a. Table I When the thiols are su?iciently basic to react 25 with acids, they may be employed as their water Induction period in soluble salts of acids, such as hydrochloric acid. J _ minutes carbonic acid and the like. When the tniols are N 0. Treatment suiiicientiy acidic to react with strong bases, they No 0.00257 BuPAP BuPAlg may be employed as their water-soluble salts of 30 bases, such as ammonia, sodium, potassium and l. _ ___ None (no coéiper added) _____________ __ 130 380 the like. 2.____ IP. P. M. u ...................... __ About20 65 Ordinarily, the aqueous solutions will be dilute, Plus 1 P. P. M. Cu and shaken with ' thelollowing aqueous solutions: containing the thiol or its water-soluble salt in 3. _ _ -_ 1% N-guanylthiourea carbonate. _ _ 115 330 NHr-C-NH: 2 NH=C—_NH| a concentration or‘ from 0.1 to 10%. It will gen 35 4. _ ___ 1% thiosemicarbazlde ___________ __ 105 325 5. . . ._ 1% beta-hydroxyethyl mercaptam. 90 340 erally be preferred to employ them in a concen 6. _ _ _ _ 1% cysteine hydrochloride. _ 100 300 tration of about 1%. Higher concentrations than 7. _ _ _ _ 1% decanedithiol-l,l0 _____ - _ 95 290 8_____ 10917 sodium sul?de.-__ 60 250 10% may be employed where the thiol or its 9.-.“ 1% lauryl meroaptan ____________ __ 30 80 water-soluble salt is su?iciently soluble in water. The upper concentration which may be used will It will be observed that 1% solutions of the be ?xed by the solubility of the thiol or its salt. organic reagents belonging to this class are more Where the organic substance to be puri?ed is effective that even 10% sodium sul?de, a com a liquid at atmospheric temperatures, it will ‘gen pound widely used by the petroleum industry for erally be found most convenient to carry out the the removal of copper from copper sweetened washing at atmospheric temperatures. Where gasoline. It will also be noted that a mercaptan, the organic substance is quite volatile, lower tem not possessing water-solubilizing groups in addi peratures down to just above the freezing point tion to the —SH (lauryl mercaptan), is practi of the aqueous solution may be employed. In cally ineffective. ' other cases, where the organic substance melts at a temperature between atmospheric temperatures 50 Table II and 100° C. and where the organic substance is quite viscous at atmospheric temperatures, it will‘ Induction period in generally be desired to employ temperatures minutes above atmospheric up to about 100° C. In some cases, it will be possible to operate at tempera .55 tures above 100° C. by employing pressures su?i cient to avoid vaporization of the aqueo'us me Y dium. Any method of intimately contacting the No. - 1.- ___ 2___._ None (no Cu added) ________________ __ No BuPAP 180-195 PluslP. P. M. 0m... ............. ._ 0.0025% BuPAP 465-475 65 Plus 1 P. P. M. Cu and shaken with organic substance with the aqueous washing so lution, such as mechanical agitation in a tank or 60 other vessel vor counter?ow contact through a packed vertical tower, may be employed. Treatment the following aqueous solutions: 3. ___. 4. . _ _ _ 1% thiourea _____________________ -. ' ' 5- _ ___ 6._.__ 1% sodium sul?de _______________ ._ > 180 485 150 445 155 355 40 90 In order to more. clearly illustrate our inven tion, the preferred modes of carrying the same It will be seen that the organic reagents are into effect and the advantageous results to be 65 much superior to sodium sul?de of equal solu obtained thereby, speci?c experiments are given tion strength. as follows: In order to show that the catalytically active A quantity of cracked gasoline, completely re metal is actually removed from the organic sub ?ned but otherwise untreated with chemical ad stance by our method, rather than merely de ditives such as dyes and anti-knocks, was con 70 activated, a benzene solution was prepared con taminated with 1 part per million of copper as - taining 0.05 g. of copper (as copper naphthenate) cupric oleate. Four hundred cc. of the copper containing gasoline were vigorously shaken 300 times at room temperature with 40 cc. of aqueous per 100 cc. of solution. This solution was shaken with an equal volume of a 1% aqueous solution of thiosorbit'ol.‘ The green color disappeared solutions of the copper removing compounds in a 76 from the benzene layer which became colorless. - 2,411,959 5 compounds oi heavy metals selected from the group consisting of copper, iron, cobalt, manga nese, and vanadium which comprises washing the petroleum product in the liquid state with The benzene layer was then separated from the aqueous solution and was evaporated on a steam bath, leaving a trace oi’ a brownish oil which was not water-soluble. Similar experiments were conducted with gasoline, fuel oil and an SAE 30 . a dilute aqueous solution of a member of the lubricating oil with like results. The washing with the aqueous solution removed the copper from the organic substances. group consisting of thiourea, thiosemicarbazide, N-guanylthiourea, beta-amino ethyl mercaptan ‘ ___It will be understood that the above experiments are given for ‘illustrative purposes only and that many variations and modi?cations can contaminated with dissolved catalytically active compounds of heavy metals selected vfrom the and dithiourea. 2. The method of purifying petroleum products ' group consisting of copper, iron, cobalt, manga nese and vanadium‘ which comprises washing the be made therein without departing from the spirit or scope of our invention. For example, petroleum product in the liquid state with a the concentrations of the thiols and their salts in the aqueous solutions may bev varied; the amount of the solution employed and the ex tent or treatment of the organic substance there with will vary; other solvents, such as methanol dilute aqueous solution of thiourea‘. 3. The method of puriiying petroleum products contaminated with dissolved catalytically active compounds 01’ copper which comprises washing the petroleum product in the liquid state with a and acetone, may be added to the aqueous so - lutions and other thiols and their salts, within 20 dilute aqueous solution of a member oi’ the group consisting of thiourea, thiosemicarbazide, N the scope of our invention, may be substituted guanylthiourea, beta-amino ethyl mercaptan for those employed in the experiments. Other representative thiols and their salts, which are e?ective and which come within the scope of our invention, are- ‘ Beta-amino ethyl mercaptan Beta-mercapto ethyl sulionic acid Beta-mercapto ethyl phosphonic acid Dithiourea (tautomeric) Beta-phenylaminoethane thiol and dithiourea. 4. The method 01' purifying petroleum products ‘ 25 contaminated with dissolved catalytically active compounds 01 copper which comprises washing the petroleum product in the liquid state with a dilute aqueous solution of thiourea. 5. The method of ‘purifying copper sweetened 30 Beitla1i-1(o-hydroxycyclohexylamino) ethane o Hydroxybenzal thiosemicarbazide cracked gasoline contaminated with dissolved catalytically active compounds of heavy metals selected from the group consisting oi’ copper, iron, . cobalt, manganese and vanadium which com prises washing the gasoline in the liquid state It will thus be seen that, by our invention, we 35 with a dilute aqueous solution of a member of the have provided a very eiiective method for remov group consisting of thiourea, thiosemicarbazide, ing catalytically active compounds of heavy met-v N-guanylthiourea, beta-amino ethyl mercaptan sis from organic substances andv particularly and dithiourea. ' ' from petroleum products, such as copper sweet 6. The method of purifying copper sweetened ened cracked gasoline. Our agents are more eiiec 40 cracked gasoline contaminated with dissolved ‘ tive than the well known sodium sul?de method, even when the sodium sul?de is employed in a con centration-ot 10 times that of our compounds. Accordingly, we believe that our invention con 45 stitutes a substantial advance in the art. We claim: 1. The method of purifying petroleum products contaminated with dissolved cstalytically active catalytically active compounds oi’ heavy metals selected from the group consisting of copper, iron, cobalt, manganese and vanadium which comprises washing the gasoline in the liquid state with a' dilute aqueous solution 01' thiourea. ’ unr-vm s. nm'mrcH, CHARLES J. PEDERSEN.