US1974167A - Antiknock gasoline - Google Patents

Description

Sept. 18,1934. V `VOQRH'EES 1,974,167

' ANTIKNOCK vGASOLINE Filed sept. 1. 1932 A 9 I aolzn .Ftm' 7 ma@ fa* a fr v am if l l ATTORNEY Patented Sept. I8, 1934 UNITED lSTATES AN TIKNOCK GASOLINE Vander-veer Voorhees, Hammond,. Ind., assignor to Standard Oil Company, Whiting, Ind., a corporation of Indiana Application September` l, 1932, Serial No. 631,386

Claims. (Cl. 44-9) This invention relates to processes of preparing gasoline containing hydrocarbon compounds of lead and it comprises processes wherein gasoline is chlorinated With chlorine resulting from the 5 electrolysis of fused sodium chloride in Ithe'presence of lead and the chlorinated gasoline reacted with lead-sodium alloy obtained in said electrolysis.

Tetra ethyl lead is a common ingredient in gasoline at the present time and is added to impart anti-detonating qualities to the gasoline. This anti-knock substance is customarily prepared by reacting ethyl chloride with a leadsodium alloy. Its manufacture involves great industrial hazard and the product is expensive. The tetra-ethyl lead, made in the manner just described, is then incorporated in gasoline in certain definite proportions.

It is an object of the present invention to impart anti-detonating qualities to gasoline without the necessity of preparing tetra-ethyl lead or highly concentrated lead compounds. My invention has for its object the formation of hydrocarbon compounds of lead within the body of gasoline, in other words, in situ, so that I can dispense with the necessity for transporting tetraethyl lead and with the handling of this very poisonous material.

I have now found that gasoline can be chlorinated to such an extent that significant quantities of hydrocarbon chlorides are formed therein and that such hydrocarbon chlorides, While dissolved in the gasoline, will react with metallic lead, advantageously in the form of a lead-sodium alloy, to give me satisfactory quantities of hydrocarbon compounds of lead. Both operations are thus conducted in a large volume of gasoline and the hazards attendant the use of tetra-ethyl lead, or strong solutions thereof are avoided. Moreover, my process is less expensive and anti-detonating characteristics can be given the gasoline at less cost. It is not necessary that the pure substance, tetra-ethyl lead,` be formed. So long as soluble hydrocarbon compounds of lead are formed within the body of the gasoline, as in my process, satisfactory anti-detonating properties are conferred on the gasoline. However, if desired, lead-hydrocarbon compounds having hydrocarbon radicals of the order of ethyl and 0 propyl can be formed in the body of gasoline by dissolving therein, prior to chlorination, suitable quantities of ethane, propane, and butane, 0r unsaturated hydrocarbons having a like number of carbon atoms such as, for example, ethylene.

Advantageously in my process, and in the interest of economy, I make use of the products of electrolyzing fused sodium chloride in the presence of metallic lead. The electrolysis of fused salt, to make caustic soda is Well known and is employed commercially. Ordinarily, in the operation of such electrolytic cells, chlorine is evolved at the anode and sodium plates out on a molten lead cathode. The sodium immediately alloys With the lead. When it is desired to make caustic soda the lead-sodium alloy is then reacted with water. In my process, however, I simply withdraw the sodium-lead alloy and react it with chlorinated hydrocarbons resulting from the chlorination of the gasoline by means of chlorine evolved from the same cell. Any unreacted leadsodium alloy is ultimately returned to the electrolytic cell. Thus, my process produces a gasoline containing anti-knock substances derived from sodium chloride, metallic lead, electrical energy, and the gasoline itself. Since at no time do I have present quantities of pure or highly concentrated hydrocarbon compounds of lead,

I have greatly reduced the industrial hazards in this art.

On the appended single sheet of drawings I have indicated in somewhat diagrammatic form a typical apparatus set-up which I find advantageous for use in my process.

Referring to the drawing, a chlorination vessel 1 is supplied with a chlorine inlet 2 which terminates in a plurality of distribution orifices within the vessel. Gasoline to be chlorinated enters the vessel by way of pipe 3 and provision for the introduction of ethane, propane, butane, or unsaturated hydrocarbons such as ethylene and propylene is m'ade at pipe 4. The chlorinated products together with gasoline leave vessel l by way of pipe 5 and enter reaction vessel 14 as shown.

An electrolytic cell 6 is provided with anodes 7 to which the positive terminal 8 of the electric circuit is connected. These anodes may suitably be made of graphite. Pipe 9 serves for the introduction of fused sodium chloride and lead. A body of molten lead 6a, serving as a cathode, lies along the bottom of the cell and the negative terminal 11 of the source of current is conveniently attached to metallic conduit 10 which conduit also permits the withdrawal of lead-sodium alloy from the bottom of the cell.

During electrolysis of the fused sodium chloride, chlorine is evolved at the top of the cell and leaves by way of conduit 2 to enter chlorination vessel 1. Sodium plates out on the body of molten lead cathode, alloys therewith, and the sodium-lead alloy is pumped vthrough pipe 10, pump 12 and pipe 13 to the top of reaction vessel 14. As stated, chlorination products dissolved in gasoline fowing from vessel 1 are conducted to reaction vessel 14 by pump 5 and pipe'a. A bypass 15, pump 16, vaporizer 17, and pipe 18 serve to by-pass a part of the chlorinationA product to the top of vessel 14 in close proximity to the outlet of pipe 13. This is to provide means to atomize the lead-sodium alloy so that it is finely divided before mixing with the chlorination product in reaction Vessel 14. The by-passed gasoline containing chlorinated hydrocarbons is pumped under pressure by pump 16 and vaporized to some extent in Vaporizer 17 so that when it meets molten alloy flowing through pipe 13 the alloy is atomized into fine particles.

The atomiz'ed particles of alloy drop through the body of chlorinated products in the reaction vessel. Since the molten alloy is at a high temperature, considerable heat is given up to the body of gasoline and chlorinated products and, in general, the temperature of the mixture undergoing reaction in vessel 14 is 300 to 600 F. Within reaction Vessel 14, the chlorinated compounds are converted to hydrocarbon compounds of lead which are soluble in the gasoline present and the solution is withdrawn through valved pipe 19 and cooled by cooler 20. If desired, part of the cooled product may be recycledthrough the line 21 and pump 21a back to the reaction vessel 14 to control the temperature of the reaction.

Unreacted lead-sodium alloy collects at the bottom of the vessel 14. This excess alloy is conveniently withdrawn from time to time through outlet 22 provided with valve 23 and conducted to a separator 24. The separator is provided with a screw conveyor 27 to remove spent alloy and other separating reaction products. `This arrangement is for the purpose of recovering any liquid products which flow out with the particles of lead alloy and such liquid products are withdrawn by way of pipe 26 and united with liquid product flowing out of the Vessel by way of line 19. The conveyor 2'7 is caused to rotate so as to withdraw the lead alloy from separator 24 and conduct it to a fusion vessel 29 by Way of pipe 28. Fusion vessel 29 is disposed within a furnace 30 advantageously heated by oil burners 31. Sodium chloride to be fused is fed into the fusion vessel through-inlet 34. I advantageously mix some potassium chloride with the sodium chloride in order to reduce the temperature necessary to fuse the sodium chloride. Sodium chloride melts at 772 C. but the addition of potassium chloride reduces this somewhat. As stated, excess lead alloy is also conducted to the fusion vessel 29. Should this be contaminated to any extent with gasoline containing lead compounds, most of which, however, flows from vessel 14 by way of pipe 19, I provide an outlet 32 and coridenser 33 to recover such desired reaction products by driving them off from the lead alloy undergoing fusion in vessel 29.

The mixture of lead alloy and fused sodium chloride is transferred from vessel 29 through .pipe 35 and pump 36 to the cell inlet 9 and in this manner any unconsumed lead alloy can be easily recovered for re-use. The vessels may conveniently be arranged for gravity flow from vessel 29 to cell 6.

With the apparatus shown the process'can be conducted continuously by allowing small amounts of unconsumed lead alloy to flow from the bottom of reaction Vessel 14 into separator 24'. and thence to fusion vessel 29.

In the operation of the apparatus illustrated, the electrolytic cell 6 is charged with fused sodium chloride advantageously mixed with some potassium chloride for the purpose stated above, and a layer of molten lead provided on the bottom of the cell. The cell is then operated in the usual way for preparing caustic soda. Generally the direct current is very high, usually about 8300 to 8500 amperes with a current density of 2800 amperes per. square foot at the anode. Normally the voltage is about 6.5 volts and the o-utput of a cell about 3 feet x 6 feet having 4 anodes withnan effective surface of about 3 square feet in all is roughly 495 pounds of chlorine per 24 hours. Advantageously I provide a number of such cells feeding the chlorine to a chlorine main which in turn supplies a plurality of chlorination vessels. The electrolytic cell as stated, is initially provided with a molten lead cathode which, as the electrolysis proceeds, is converted to lead-sodium alloy. Portions of the alloy are Withdrawn from time to time to provide reagent in reaction vessel 14 and, as described, excess alloy is returned to the cell. As lead is consumed in the reaction forming lead compounds, furtherl quantities of metallic lead can be added to the fusion vessel to make up for that consumed.

Virgin gasoline can be used in my process and introduced into thev chlorination vessel 1 but I find it more advantageous to chlorinate a cracked gasoline. The amount of gasoline owing intermittently or continuously to the chlorination vessel Will of course depend upon the amount of chlorine available in any unit of time. Generally I obtain a chlorine absorption of approximately .05 percent of the weight of the gasoline. Some hydrochloric acid gas may be evolved and this can be vented to the atmosphere by means of vent 25 shown at the top of the chlorination vessel.

It is usually unnecessary to add hydrocarbons such as ethylene and this is especially true when cracked gasoline is used. However, I find it advantageous some times, depending upon the character of the hydrocarbons in the gasoline, to introduce quantities of normally gaseous aliphatic hydrocarbons by Way of pipe 4. If the character of gasoline being treated is such that it is diflicult to convert small portions of 'it rap,- idly to hydrocarbon chlorides, the introduction of ethylene or propylene may be resorted to and I can thus prepare lower aliphatic chlorides within the body of gasoline. Generally speaking, quantities of material and size of apparatus should be so proportioned that the final product obtained from pipe 26 contains about 0.2 to 0.4 percent of hydrocarbon compounds of lead. This will vary with the nature of the hydrocarbon compounds, some of them being more effective anti-detonating agents than others, but, chlorination should proceed to such an extent that subsequent conversion of chlorinated products by reaction with the lead alloy will be sufficient to give me a gasoline containing approximately 0.2 to 0.4 percent of dissolved hydrocarbon compounds of lead. However, higher con-A centrations of lead compounds may be obtained and the product may be used as blending stock. 'I'hus a stock containing 4% of lead as lead compounds may be diluted with about 10 volumes of untreated gasoline to give a satisfactory antiknock fuel. The extent of chlorination governs the amount of lead compounds ultimately formed lead alloy contains from 5 to 15% of sodium.'

Such an alloy will leave the cell at a temperature at least high enough to melt the alloy (about 625 F.) and generally considerably higher since the fused salt is at a temperature of about 770 C. or somewhat less if potassium chloride is mixed therewith. When the molten alloy meets the volatized chlorination products by-passed through pipe 15, the alloy may be chilled somewhat and, at the same time, quickly atomized so that alloy falling into the body of chlorination products in vessel 14 is in a finely divided condition. This of course is desirable since it promotes reaction. Sometimes the lead alloy, after being atomized, remains molten. In this event, the atomized liquid mixeswith theA body of liquid hydrocarbon in the reaction vessel as a nely divided temporary suspension. However, as it settles down through the body of hydrocarbon, it solidies in small particle form.

The heat derived from the hot lead alloy is usually suicient to heat up the contents of the reaction vessel to reaction temperature, advantageously about 300 to 600 F. Further quantities of heat are also imparted to the contents of the vessel by the vaporizer 17. The reaction Vessel should be large enough to give adequate time of contact between the particles of lead alloy and the liquid therein before the alloy collects at the bottom of the vessel.

The best temperatures to be maintained within the reaction vessel depend upon the composition of the alloy. Whenvthe content of sodium therein is low, in the neighborhood of 2 or 3%, somewhat higher temperatures, 600 F. yor more, are necessary and, when the sodium content is high, about 15%, lower temperatures around 300 F., are satisfactory. However,'if the sodium content of the alloy is too high the current efficiency 'of the cell will be low. I therefore so regulate the action of the cell that I obtain an alloy containing from 5 to 15 percent of sodium. This gives me satisfactory currentefciency in the cell and also sufficient' sodium in the alloy to obtain satisfactory reaction temperatures and reaction rates Within the reaction vessel 14. An alloy containing 5 to 15 P' percent of sodium will react satisfactorily at any temperature within the range of 300 F. to 600 F.

Should the sodium content of the alloy ,be below 5 percent, and thus require a reaction temperature of over 600 F. in the reaction vessel, I can f supplement the 'heat derived from the molten alloy by by-passing and vaporizing more chlorination products through pipe 15. Sometimes it is desirable to operate at reaction temperatures such that the lead alloy retains its molten state throughout the reaction. This of course requires that the alloy shall not be chilled below solidifying temperature during the atomizing stage and I accordingly by-pass and vaporize more chlorination products when this is desired. In such case the molten alloy which has not been consumed collects in the bottom of the reaction Vessel and is run oi through outlet 22. Such molten alloy contains practically no liquid reaction products and I can therefore dispense with the separator and conveyor arrangement, and conduct the molten alloy directly to the fusion vessel for recovery and re-use. A

Since the reaction vessel is maintained at a high temperature, in excess of the boiling point of the .hydrocarbon fluids therein, it is necessary that the whole system be kept under pressure sucient to maintain the hydrocarbon fluids in the liquid condition. This pressure varies with the temperature and may be about 300-800 pounds per square inch.

It will of course be obvious that other arrangements of apparatus can be employed together with numerous details to facilitate the handling of the materials. I therefore do not wish to be bound by the specific form of apparatus illustrated.

The gasoline product obtained in my process contains 0.2 and 0.5 percent or more of dissolved hydrocarbon compounds of lead the hydrocarbonI radicals of which have been directly derived from the gasoline itself. This product is highly antidetonating and is superior to gasoline made by the addition of antiknock substances. Although I am not prepared to state the exact nature of the leadhydrocarbon compounds in my gasoline-I believe that they are more complex in chemical structure than the simple alkyl compounds and their hydrocarbon `radicals contain in general at least 4 carbon atoms. They are probably mixtures of lead derivatives of various isomeric liquid hydrocarbons having from 4 to 7 carbon atoms.

Althoughas statedtabove, conversion of chlorinated hdrocarbons to ladcompounds appears to be substantially quantitative, small amounts of chlorinated hydrocarbons may be left in the nal.

product and assist in the antidetonating action of the lead when the fuel is burned in the engine. The quantity of lead compounds formed in the operation is determined by the extent of chlorination. I may discard part or at times, all of the chlorine through valved line 2a, to control the extent of chlorination. For this reason I have not specically claimed any particular proportional composition of gasoline and lead hydrocarbon compounds.

I also find that my gasoline product is practically sulfur free because of the fact that such sulfur compounds as may be present in the gasoline are taken out by the lead alloy. Thus the alloy not only converts chlorinated hydrocarbons to lead compounds but also desulphurizes the gasoline. This is particularly advantageous since the raw gasoline entering the system need not be highly desulfurized. I find that in my process where the chlorinated hydrocarbons are dispersed in a large Volume of gasoline, they may be converted into lead derivatives at higher temperatures without decomposition of the resulting derivatives.

Having thus described my invention, what is claimedis:

1. The process of preparing gasoline containing,

lead compounds which comprises electrolyzing fused sodium chloride in the presence of lead to form chlorine and a lead-sodium alloy, reacting the chlorine with gasoline to form chlorinated hydrocarbons therein, and treating the gasoline containing the chlorinated hydrocarbons with the lead-sodium alloy to convert the chlorinated hydrocarbons to hydrocarbon compounds of lead.

2. The process of preparing gasoline containing lead compounds which comprises electrolyzing fused sodium chloride in the presence of lead to form chlorine and a lead-sodium alloy, reacting the chlorine with gasoline- -containing dissolved, normally gaseous, hydrocarbons to form chlorindrocarbons to hydrocarbon compounds of lead,`

separating the gasoline containing the hydrocarbon compounds of lead from unreacted lead-sodium alloy, and uniting the latter with further quantities of fused sodium chloride to be electro,

lyzed.

4. The process of preparing gasoline containing lead compounds which comprises electrolyzing fused sodium chloride in the presence of lead to form chlorineand a lead-sodium alloy, reacting the chlorine with gasoline containing dissolved, normally gaseous, aliphatic hydrocarbons to form chlorinated hydrocarbons therein, treating the gasoline containing the chlorinated hydrocarbons with the lead-sodium alloy to convert the chlorinated hydrocarbons to hydrocarbon compounds of lead, separating the gasoline' containing the Y hydrocarbon compounds of lead from unreacted Ylead-sodium alloy, and uniting the latter with further quantities of fused sodium chloride to be electrolyzed.

5. The process of preparing cracked gasoline' containing lead compounds which comprises chlorinating the gasoline with chlorine, derived from the electrolysis of fused sodium chloride in the presence of lead,/ to form chlorinated hydrocarbons and treating ther chlorinated hydrocarbons with the lead-,sodium alloy resulting from such electrolysis to form hydrocarbon compounds of lead. i

VANDERVEER VOORHEES.

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