US1939839A - Refining of mineral oils by means of alloys or loosely bound compounds of alkali metals - Google Patents

Description

1933. E. c. WILLIAMS ET AL 1,939,339

REFINING OF MINERAL OILS BY MEANS OF ALLOYS QR LOOSELY BOUND COMPOUNDS 0]? ALKALI METALS 7 Filed Aug. 10. 1929 Trear'ed 02/ Our/cf Wafer Spray /5 D/sperser 9 I I Coo/er Reduc/hg Wash Tower LG/V 4 4 Treafing Tower 2* Preheafer Gauge Mercury Pas/hue Co//e cror E/ecfro/ r/c Alma/90m Pump 7 Mercury 5 forage Ama/gam Ol/ [/7 er Sforage [Nvs/vToRs EVAN CL/FFOPD l Mum/ws HERBERT PETERAf/GLSTLCS GRULL 5v THE/R ATTORNEY:

Patented Dec. 19, 1933 UNITE ST REFINING OF MINERAL OILS BY'MEANS F ALLOYS OR LOOSELY BOUND COMPOUNDS OF ALKALI METALS Application August 10, 1929. Serial No. 384,942

'iClaims. (Cl. 196-23) This invention relates to the refining of mineral and other oils and particularly to the sweetening of cracked products from petroleum, in future referred to as cracked distillate. The invention consists in treating the mineral oil with loose compounds of an alkali metal,- or mixtures of such compounds, preferably in a continuous process.

These compounds are defined by the character? istic that they are decomposed by water to the hydroxides of the alkali metal used. Such compounds are, for instance, the amides, alcoholates, amalgams, or alloys of alkali metals.

Further features and advantages of our invention will appear from the following description of one method of carrying the invention into effect. It will be understood that we do not limit ourselves to the details of this particular method of using our invention, but we extend our claims for the principle of our invention as far in scope and equivalents as thestate of the prior art will allow.

The present invention is applicable to many oils, especially mineral oils such as petroleum oils or oils derived from coal or shale, but we will describe it particularly with reference to the treatment'of cracked distillate obtained by crack ing from petroleum oils, which is one of the most difficult petroleum products to refine.

We found that when metallic sodium was placed in cracked gasoline of foul odour, it became coated, in the course of days, with deposits of gum-like resins and other solid material, indicating a marked reaction. while the odour of the gasoline improved.

The cost of metallic. sodium, and still more, the danger of using metallic sodium in a refinery (sodium reacts violently with water, and the hydrogen evolved ignite spontaneously), makes its use quite out of the question. 7

We therefore investigated the possibility of using loose compounds of sodium or' other alkali metals which would show a similar effect to that of. metallic sodium on the mineral. oils without its disadvantages. We-foundsuchcompounds as the ami'd'es, alcoholates, amalgams oralloys of alkali metals to be refining agents for mineral oils. This refining action is due partly to removal of sulphur compounds and other undesirable substances which form compounds, with the alkali metal, and partly to the polymerization of unstable and therefore undesirable constituents to form gums or resins. These polymerized gums or resins are in part precipitated in the form of sludge together with the alkali metal compounds formed during the process as mentioned above,

features described in this. example:

and in part, remain dissolved in the oil. Pref.-

erably we redistill the oil treated according to our invention in order to free it from these polymerized and high boiling gums. r

. The following is an example of one of the most useful methodsof applying ourinvention forthe refining of mineraloils by the action of alkali metal amalgams. It may be understood weare not confining-ourselves'to any'of theparticularv .A solution of sodium or potassium amalgam in mercury is usedlas refining agent. The concentration of .the amalgam is keptlow enough tokeep'. this solution liquid at thetreating temperature. 'I'he'mineral oil can be treated atnormalor' at" elevated temperature, preferably around 100 C. at which temperature the velocity of the reaction is sufficientlyhigh. ,If thetemperature is allowed to rise higher tl'ia n' 150 C; the refining action is less eifective 'andthere is excessive reaction be tween mercury and the sulphur compounds in the oil, as a result of which mercuric sulphide is formed. As the temperaturerises this compound is formed in increasing amounts thus making the recovery of the'used mercury more complicated and the process less practicable. We there: fore prefer to operate at a temperature not exceeding 100C.

At a treating temperature of 100 C. a solution of amalgam'in mercury containing more than 1.5% sodium or 2.0% potassium is liable to ,crys: tallize and thisfrenders impracticable any circulationof the amalgam solution as described hereunder. 'We therefore operate witha solution of amalgam containing not more'than 1% sodium and preferably 0.7%. When potassium amalgam is used it is possibleto operate with a'slightly higher concentration of the alkali metal; v

The use of a liquid solution of'alkali metal r amalgam in mercury is advantageous from sev-' eral points of View: first, it can be manufactured cheaply by the electrolysis of alkali metal salt solutions, which manufacture is thoroughly established in the chemical industry. This avoids the necessity of preparing the amalgam by dissolving metalic sodium or potassium in mercury, a 'method which, because of fire hazard, is too dangerous to employ in an oil refinery and because of the high price of "these metals, is entirely uneconomical as a means of refining gas oline; Second, the diluted amalgam does not re act vigorously with water, and never such rate as to ignite the hydrogen evolved. Third, the dilute' amalgam, being in the liquid state, may bev circulated in a continuous plant; as a liquid in to the oil and does not become coated with a layer of polymerized gums; consequently, the amalgam reacts more readily and more completely than a solid compound of'similar nature. As a consequence. of this more ready reaction, the. refining in our process is completed in to minutes, whereas with solid metals 'or alloys in a manner wellknown to those 'skilledin' such operations, to agitate-the amalgam-on the sevthe refining may take several hours.

I For the sake of brevity this solution of. alkali metal amalgam in mercury as specified above will be referred to in the future as .amal'gam.

It will be understood that there are many different ways of carrying thisinvention into practice: all of which have as their object bringing the amalgam or other alkali metal compound into:

intimate contact with the. mineral oil to be treat ed in a continuous and preferably counterecurrent manner.

For example, the amalgam or other alkali metal compound may be brought'into reaction by agitating it in contact with the cracked distillate in a single vessel or in a number-of vessels arranged in series throughwhich the amal gam and cracked distillate are rnadeftojpass in, a counter-current manner.

Alternatively, such a series of vessels' may be replaced by a tower fitted with a number of superimposed'trays,down which amalgam flows from tray to tray, and up which the distillate to be treatedpasses, arrangement. being made i 1 treated iscaused to flow. I

cathodev is so arranged that it is'in'contact on one hand With'electrolytaand on the other with.

'the mineral oil. v V

reacts; directly with the cathode, which latter is caused to flow.

Alternatively, the mineral oil to be treated may be made to react with the amalgam in a compartment adjacent toorforming an integral part I of the electrolytic cell in whichthe mercury the mineral oil to be treated; The mercury amalgam cathode may be agitated'in any preferredway-in order to facilitate reaction with In this manner the mineral oil provides 'a supply ofsodium continuously from the electrolyte to the oil, a .The] attached drawing illustrates enr'iployed' with good results for the application of our invention, using the principle of atomizing amalgam into the upper part of a vertical treat ing tower, up which the mineral oil tobejtreated is byno means the final form of our plant, as longer practice probably will require improvements and alterations Without, however, changing the principle of our invention.

The mineral oil used in this example is a cracked distillate, previously subjected to the normal acid and soda. wash treatment, and containing about 60% of gasoline fraction. The appropriate. sections of the apparatus must therefore .be capable of withstandingthe pres.-

sures' of 100-200 lbs. per sq.'inch developed at the treating temperature. r

The apparatus consists mainly of l, preheater;

2, treating tower; 3, cooler; 4, water washtower;

I more or less diagrammatically an apparatus which we have It Will be understood that'this ,ceed 1.'0% oftheamalgam solution? V 1,939,839 .motion it continuously presents affresh surface 5, separator for sludge and mercury; 6, mercury storage tank; 7, electrolytic cell; 8, amalgam storage tank; 9, amalgam disperser; 10, mercury residue collector.

g In the operation of thi's 'apparatus the cracked distillate to be treated is introduced through line 7 '11 to pump 12 and pumped through preheater 1,

which may consist in part of a heat exchanger,

1 to treating tower 2, which may also be heated.

It is met in this tower by a descending counter flow of amalgam. The treated cracked distillate leaves the top of tower 2 by a side arm 13, and passes to the cooler 3, beyond which, at valve l4 the pressure is reduced to approximately atmospheric. It then passes to the bottom of wash tower 4,- where it is washed in counterflow by water or dilute caustic soda from spray 15. The Wash; water and sludge which lattercontains a little finely divided mercury or mercury sulphide 'are'collected in receiver 10, while the treated oil leaves by line 16. The sludge from receiver 10 is worked up by any suitable process, as, for instance, by, filtering, centrifuging, roasting, etc. to recover the small'amount of mercury which it contains; The sludge collected atsepar'ator '5 is separatelywashed with water andthen subjected to the same recovery process. Any oil whichseparates during the washing of this sludgefis re turned to the cracked "distillate storage. Thetreated cracked distillate is distilled, preferably" with open steam, for'the preparationfof gasoline of suitable endpoint, and the separation of any high boiling polymerized products.

7 Mercury stored'in tank '6 is passed "to electrolytic cell- '7, where sodium amalgam is formed.

Thispasses by gravity to storage tank 8, whence pump .17 passes itfto the amalgam disperser 9,

from which thedispersed amalg'ainifalls directly into treating tower 2." The mercury, denuded of sodium by reaction with the undesirable constituents of the cracked distillate, collects at the bottom of tower2, and is returned to storage tank 6, through the sludge separator 5. 7

In actual operation, more parts and instruments may be added which have been omitted here for the clearnessjof the description, as theycan readily be added by those skilled in'the artljj a The outlet ofthedistillate from tower 2 is so arranged by ineansoi the side-arm lsth'atnone, or at worst very little, of the heavyamalgam can pass out of the towerwith the distillate." V

. The oils treated by any methods of our inven-' tion are distinguished'by' their pleasant odour,'. water white colour,'-colour stability in sunlight or darkness, and negative doctor test; In these respects especially, the cracked gasoline treated by ourprocess is'far'superiorto cracked gasoline refined by the usual processes.

We claim 'as our invention: 1

1., A process for the refining of' o'ils cQmprisingtreatingithe oil with alkali metal amalgams whose alkali metal content does not'exceed 1%" of the amalgam. v

i 2. A process for refining mineral oils, comprising'treating' the mineral oil with sodium amalgam whose sodium content does not exceed 1% of the anti'a a i J 1 3. Aj'process for the refining, of cracked pe- 'troleum oils, comprising treating the oil with a solution of sodium amalgam in m'ereurm the "'lsodium content of which solution'does not dium content of which solution does not ex-.

ceed 1% of the amalgam solution, at about 100 C.

7. A process for the refining of oils comprising treating the oil with an alkali-metal amalgam whose alkali-metal content does not exceed 1% of the amalgam, at about 100 C.

EVAN'CLIFFORD WILLIAMS.

HERBERT PETER AUGUSTUS GrROLL.

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