US2744126A

US2744126A - Preparation of lead-sodium alloy and tetraethyllead

Info

Publication number: US2744126A
Application number: US159575A
Authority: US
Inventors: Edwin L Mattison
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1950-05-02
Filing date: 1950-05-02
Publication date: 1956-05-01
Anticipated expiration: 1973-05-01

Description

May 1, 1956 E. L. MATTISON PREPARATION OF LEAD-SODIUM ALLOY AND TETRAETHYLLEAD Filed May 2, 1950 REACTOR INVENTOR.

EDWIN L. MATT/SON BY ziazw w ATTORNEY RECEIV E 12 PREPARATION OF LEAD-SODIUM ALLOY AND TETRAETHYLLEAD Edwin L. Mattison, Newark, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application May 2, 1950, Serial No. 159,575

'18 Claims. 01. 260-437) This invention relates to the preparation of lead-sodium alloy especially adapted for use in the manufacture of tetraethyl lead and, particularly, to alloy which has increased reactivity toward ethyl chloride.

Prior to my invention, the commonly employed'method for making commercial lead-monosodium alloy has been by the batch process. Liquid sodium and liquid lead, in the weight ratio of 1:9, have been fedby gravity from scale tanks into a manufacturing pot provided with an agitator, a jacket for removal 'of the heat of formation of the alloy, and induction heating to maintain the alloy in molten condition after it is formed; all substantially as disclosed by Amick et al. in Patents 2,043,224 and 2,091,801. When the required proportions of lead and sodium have been alloyed, the moltenalloy is pumped to an agitated distribution pot which is also provided with induction heating, and thence to a battery of oil jacketed casters of the character disclosed by Stecher in Patent 2,134,091. Such casters are long rectangular chambers in which the alloy is allowed to cool batchwise in relatively thin layers. After the alloy has solidified, the caster is set to vibrating and the alloy is broken up and discharged to a grinder of'the character disclosed Y the vibrating feature in the 'cooler moves it to the discharge port where it is loaded into-hoppers. The hoppers must be transported to and-connected with the autoclaves in which the tetraethyl lead is manufactured All of these operations must'be performed in an of nitrogen or other inert gas.

' The alloyis fed from the hoppers into the autoclaves where it is agitated and heated to about C. to about C. Ethyl chloride is then added tothe autoclaves and held in contact with the alloy for 2 to about 4 hours to complete the formation of tetraethyl lead by reaction of the ethylchloride with'thelead-sodium alloy. Theoretically, *1 part] by weight of ethyl chloride to 3.57 parts of lead-sodium alloy 'is required. However, in practice, a small excess of ethyl chloride is employed, usually, about excess. Care is taken to maintain atmosphere size.

the temperatures in'the autoclaves'below 100 C. be-

cause tetraethyl lead tends to decompose rapidly at temperatures slightly above 100 C., and with explosive violence at materially higherv temperatures. After the reaction is complete, the excess ethyl chloride is distilled off and the reaction mass is transferred to a steam still where the tetraethyl lead is distilled off. v

' The prior processes of preparing the alloy :and transporting it to the autoclaves are'expen'sive to operate and require elaborate and costly equipment. The alloy is not uniform in size, varying from small chunks to a fine powder, and does not have maximum reactivity toward ethyl chloride, whereby undesirably long periods of time are required to complete the reaction withfethyl chloride..Furthermore, because of the physical condi-' tion of the alloy and its slow reactivity,-it has been a 2,744,126 Patented May 1, 19 56 "ice ' known.

It has been proposed, in Patent 2,109,005, to make particles of lead-sodium alloy by cooling the molten alloy to a temperature below that at which particles of the alloy tend to adhere to each other and stirring the mass during such cooling. When properly operated, this gives particles of uniform size. In spite of this advantage, I however, such processstill has the disadvantages of requiring special, costly equipment and careful Marketing with large quantities of nitrogen and does not lend itself to plant scale operations or to incorporation into a continuous process for making tetraethyl lead.

Nourse, in Patent 2,310,806, has proposed grinding solid lead-sodium alloy in liquid ethyl chloride and reacting such'alloy with the ethyl chloride. This and like expedients have resulted in alloy of greatly decreased reactivity and the production of low yields of tetraethyl lead.

Voorhees, in Patentl,974,l67, has proposed the manufacture of gasoline containing lead-hydrocarbon compounds by atomizing molten lead-sodium alloy and dropping it. intochlorinated gasoline maintained at 300 F. to 600 F. (l48.89' 'C. 'to 315.56 C.), whereby the alloy is simultaneously solidified and reacted with the chlorinated hydrocarbons. He thereby obtains complex lead-hydrocarbon compounds, other than tetraethyl lead, which are less efiective than tetraethyl lead as anti-knock agents. Such process is impractical because it involves the treatment of large volumes of material at temperatures of at least 300 F., requiring large and expensive equipment, and the reaction with the chlorinated hydrocarbons in such dilute solution is incomplete so that the resulting gasoline will contain objectionably large amounts of corrosive chlorinated compounds. I i

It is an object of my invention to provide an improved process for preparing lead-sodium alloy in asimple and economical manner which requires relatively simple and inexpensive equipment and overcomes the disadvantages of the prior art processes. Another object is to provide a process for preparing lead-sodium alloy in a form in which it has increased reactivity toward ethyl chloride. Still another object is to provide a process for preparing lead-sodium alloy in particles of uniform and controlled A further object'is to provide a continuous process for preparing a slurry of lead-sodium alloy in ethyl chloride, particularly adapted for use in a continuous process for making tetraethyl lead and which continuous process of preparing such slurry can be combined in a continuous process for making tetraethyl lead. V A still further object is to advance the art. Other objects will appear hereinafter.

The above and other objects may be accomplished in accordance with my invention which comprises passing a streamof moltenlead-sodium alloy, containing from 9.9% to l0.1%-by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than /2 inch in diameter 'and then into a violently agitated body of liquid ethyl chloride maintained at a temperature of from about 50 C. to C. in a quenching chamber, employing about 1 part of alloy to from 9 parts to 1 part by weightof ethyl chloride and forming a slurry of unreacted alloy in ethyl chloride in which the alloy is in the form of bright solid particles of a uniform size up to about 8 mesh in size. The resulting lead-sodium alloy particles are initially unreactive toward ethyl chloride but, after a period of time, are substantially more reactive than alloy prepared by other methods, and are peculiarly adapted for making tetraethyl lead; .The slurry, .so produced, may then be transferred to a reactor for reaction to produce tetraethyl lead, or the alloy particles may be separated from the ethyl chloride and subsequently employed in the manufacture of tetraethyl lead, the slurry being passed to the reactor or the alloy being separated from the ethyl chloride while the particles of alloy are still bright. Such process may be operated as a batch process or as a continuous process.

It is well known to the art that lead-sodium alloy reacts with ethyl chloride at ordinary temperatures and quite rapidly at higher temperatures, such as 35 C. to 70 C., as shown by Kraus et al., in Patents 1,612,131 and 1,697,245. However, lead-sodium alloy melts at about 366 C. Accordingly, it would be expected that, if molten alloy were added to ethyl chloride, the hot alloy would immediately heat the ethyl chloride in contact therewith to high temperatures with simultaneous reaction, and that, as the addition of the molten alloy was continued, some of the hot alloy would contact tetraethyl lead in vapor or liquid form with resultant decomposition of the tetraethyl lead and, probably, with resultant explosions. However, I have found that such expected results are not obtained if the addition of the molten alloy to the ethyl chloride is accomplished under properly controlled conditions.

I have found that, when a stream of molten alloy is added to a body of violently agitated ethyl chloride maintained at a temperature of 90 C. or below, the alloy is solidified and cooled to the temperature of the ethyl chloride (quenched) in less than 1 second and, probably, less than 0.1 second, without reaction with the ethyl chloride. I have further found that such cooled alloy and the ethyl chloride can be maintained in contact for appreciable periods of time without reaction; i. e., the alloy particles, when first formed, are unreactive toward ethyl chloride but, after a period of time, become highly reactive. Stated another way, there is a well defined induction period at 90 C. and below before reaction between the alloy and the ethyl chloride occurs and during which no reaction takes place. The alloy particles are clean, bright, and silvery in appearance, when first formed, and retain such appearance until reaction with ethyl chloride starts. When such reaction does start, the particles of alloy promptly lose their bright appearance and acquire a black coating. Such induction period varies inversely with the temperature of the slurry, being about 30 seconds at 90 C. and increasing more and more sharply as the temperature is decreased, particularly at temperatures of 35 C. and below. Approximate induction periods in minutes at representative temperatures are shown below:

Temperature, Induction minutes period The substantially instantaneous quenching of the alloy and the induction period provide sufficient time for the practical formation of the desired slurry and separation of the alloy from the ethyl chloride or passage of the slurry to a reaction vessel, while the particles are still bright and before reaction between the alloy and the ethyl chloride takes place. It is merely necessary to determine the amount of time which will be required to carry out the selected procedure, and then to maintain 4 the slurry at a temperature having an induction period at least equal to such time.

It is well known to the art that lead-sodium alloy, containing 10% sodium by weight, is the most efficient for the production of tetraethyl lead and gives the high est yields, and that very slight variations in the composition of the alloy seriously decrease its etficiency and the yields of tetraethyl lead. Accordingly, it has been necessary to exercise great care to obtain alloy of such exact composition. However, I have found that leadsodium alloy, containing from 9.9% to 10.1% by weight of sodium, may be treated by my process to obtain alloy of equal reactivity toward ethyl chloride. Materially wider variations in the composition of the alloy are still deleterious. This permissible variation in the composition of the alloy, while apparently slight, is important as it reduces the necessity for rigid control of the com position of the alloy, whereby alloy of maximum efliciency can be manufactured more easily and economi' cally.

When the ethyl chloride, employed for quenching the alloy, is to be used to react with the alloy to make tetra ethyl lead, as when the slurry is passed to a reactor, it will, preferably, contain a small proportion of an accelerator of the reaction of the character disclosed in Patents 2,426,598, 2,464,397, 2,464,398, 2,464,399 and 2,477,465. The preferred accelerator is acetone which will be employed in the proportion of about 0.1% by Weight based on the ethyl chloride. The presence of such accelerator does not materially reduce the induction periods hereinbefore disclosed under the conditions of my process.

It is well known that lead-sodium alloy is reactive to oxygen and moisture and hence it is conventional practice to protect the alloy by an atmosphere of an inert gas, such as nitrogen and helium. It will be understood that such conventional practice is followed in my process. Before introduction into the ethyl chloride and after separation therefrom, the alloy is conventionally protected by an atmosphere of such an inert gas. During the quenching and subsequent steps, the alloy is protected by liquid ethyl chloride and vapors thereof above the liquid, which may be supplemented by nitrogen or other inert gas, particularly where gas pressure is desirable for forcing the slurry through pipes and the like.

The process may be carried out in various ways and in various types of equipment. A simple method comprises placing the ethyl chloride in a quenching chamber in the form of a vessel equipped with mechanical stirring means and, preferably, with a reflux condenser, stirring the ethyl chloride to give it a velocity between 25 and 1000 feet per minute, and passing a stream of molten alloy into the agitated body of ethyl chloride. The temperature of the ethyl chloride throughout the process is conveniently regulated by refluxing of the ethyl chloride and, for this purpose, the equipment is maintained under a pressure determined by the temperature desired. The rate of addition of the alloy is also adjusted according to the desired temperature of the slurry so that all of the alloy is added in materially less than the induction period for such temperature. After the addition of the alloy is completed, the agitation is stopped, whereby the alloy rapidly settles to the bottom of the vessel. Then most of the ethyl chloride is decanted off and the rest is removed from the alloy by evaporation. The evaporation of the ethyl chloride will usually be accompanied and aided by passing an inert gas, such as nitrogen and helium, through the vessel and, preferably, through the bed of alloy, so as to replace the ethyl chloride with the inert gas. The entire process is completed within the induction period for the temperature of the ethyl chloride.

When the temperature is regulated by the boiling of the ethyl chloride, the following table may be used to particles are still bright.

ethyl chloride.

determine the'pre'ssureat which the system .is to be maintamed to obtain substantiallythetemperatu're desired.

Temperature, vCi:

Pressure, lbs. per sq. in. absolute 0.6

'In the rnethodjust described, the ethyl chloride will psually be maintained at C. or below so that the induction period will be of a length to provide suflicient time for ready. completion of theprocessand separation of the ethyl chloride from the alloy while the alloy Temperatures below C. may be used, but will usually be economically impractical. ,More than 9 parts by weight of ethyl chloride to each part of lead-sodium alloy may be used, but usually will be uneconomical and inefiicient because of the large excesses of ethylchloride to be handled and recovered.

Less than 1' part of ethyl chloride for each part of leadsodium alloy renders the slurry so thick that eflicient agitation is quite diflicult. Preferably, I employ from about 2 to about 4 parts by weightof ethyl-chloride to each part of lead-sodiurnalloy. The temperature of the ethyl chloride during such process may be controlled by methods other than refiuxing of the ethyl chloride. It may be controlled, wholly or in part, by passing a cooling fluid over the outer surface of the quenching vessel or through cooling coils immersed ..in the ethyl fchloride.-. In many cases,v it is preferred to maintain a pressure well above that at which boiling willoccur and to control the temperature by the initial temperatures of the alloy and the ethyl chloride. Thetemperatures and pressures involved are moderate.

Usually, the temperature is controlled by having the initial temperature of the ethyl chloride lower than the desired temperature of the slurry by an. amount such that the ;heat of the alloy will be absorbedby the ethyl chloride withoutboiling and bring the slurry to the desired final temperature. I

, The alloy has a heat of fusion of only 8.1 calories per I gram and a heat capacity of only 0.05 6 calorie per'gram per "C. 'Ethyl chloride has a heat capacity of 0.368

calorie per gram per -C. Therefore, the required initial temperature of the ethyl chloride may be readily calcuvdated by those skilled in the art accordingto the formula Wam- 0.368E, Te

wherein Ta represents the initial temperature of the alloy, Ts represents the final temperature of the slurry, E represents the parts by weight of ethyl chloride for each part of alloy, and Te represents the initial temperature of the Representative calculated increases in the temperature of the ethyl chloride, produced by quenching molten alloy at 430 C. in varidus amounts of ethyl chloride,"=and-required initial temperatures of the ethyl 30'*' C., areshownin-the following table:

' Increase in g g f f Parts Ethyl Chloride Per Part Alloy Temperature Eghyl i ride C.)

a 2 e +20. 8 20. 7 +9. 3 27. 6 +2. 4 41. 4 11. 4 82. 8 I 52. 8

Such calculated figures correspond tained'in practice. p

The size of the particles of alloy produced is dependent, mainly, upon the violence with which the ethyl chloride and stream of molten alloy come into contact and, to a lesser extent, upon the diameter of the stream of alloy. The diameter of the alloy stream entering the liquid ethyl weu with those obchloride should not be larger than substantially /2 inch and, usually, will be 'less. The size of the molten alloy stream .is controlled by passing it through an orifice'of less than /2 inchin diameter and, preferably, less than inch in diameter. The minimum size of orifice, which can be employed, is dependent solely" upon ability to force the molten alloy through it at the desired rate Without clogging, and, appears to be about inch. Obviously, molten alloy streams of more than inch in diameter require more violent contact with the ethyl chloride than streams of smaller diameter in order to obtain alloy particles of corresponding size. The orifice and feeding means containing it, such as a nozzle, will be out of contact with the liquid ethyl chloride so as to avoid freezing of the molten alloy before the alloy has passed through the orifice.

The violence with which the ethyl chloride contacts the stream of molten alloy is dependent upon the violence of the agitation. vThe particle size decreases with increase in the violence of agitation or velocity of the ethyl chloride in which the alloy is quenched. When the stream of molten alloy is less than about Vs inch, the average size of the solid alloy particles will vary roughly from about 8 mesh to about mesh as the linear velocity of the ethyl chloride is varied from about 25 to about 500 feet per minute. Alloy particles of about 10 to about 40 mesh will usually be obtained at linear velocities of from about 50 to about 250 feet per minute and particles of from about 10 to about 20 mesh at linear 'velocities of from about 50 to about feet per minute.

ferred that the alloy have a particle size of from about 10 mesh to about 40 mesh, particularly from about 10 mesh to about 20 mesh, because of convenience in physical handling.

The agitation of the ethyl chloride, during the quenching, may be produced by means other than mechanical stirring. Sufiicient agitation may often be obtained by injecting themolten alloy into the ethyl chloride at a rate sufficient to cause the ethyl chloride to boil violently. The stream of alloy may be introduced into a flowing stream of ethyl chloride. Also, the ethyl chloride may be injected into the quenching vessel in one or more streams at high velocity, preferably, tangentially of the vessel, and injecting the stream of molten alloy into the whirling ethyl chloride substantially simultaneously, particularly as willbe described in more detail hereinafter in connection with the continuous process and the accompanying drawings. By maintaining the rate of feed and velocity of the streams of alloy and ethyl chloride substantially constant during the quenching alloy of-substantially uniform particle size is obtained.-

7 Other methods of separating the alloy from the ethyl chloride may be employed, such as 'by evaporation of all of the ethyl chloride or by filtration. The separation need not be accomplished in the quenching vessel, as the slurry may be caused to flow from the quenching vessel to a filter or to a separate settling tank or tanks and the alloy then passed to dryers, for batch or continuous operation.

Preferably, the process will be carried out continuously and particularly as part of a continuous process for making tetraethyl lead. In such continuous process, the ethyl chloride is continuously added to the quenching vessel or chamber and the slurry continuously removed from the quenching chamber substantially as fast as it is formed and passed to equipment for continuously separating the alloy from the ethyl chloride, such as filters or one or more settling and decanting tanks and evaporators, or to one or more reactors, while the alloy particles are still bright.

In such continuous process, the pressure in the quenching chamber will preferably be maintained well above that which would permit boiling of the ethyl chloride, usually about 50 to about 100 pounds above, and the temperature will be controlled by means other than refluxing of the ethyl chloride. slurry may be controlled conveniently by passing a cooling liquid over the outside of the quenching chamber or through cooling coils in contact with the ethyl chloride in the quenching chamber. Preferably, however, the temperature of the slurry is controlled by supplying the ethyl chloride at a lower initial temperature so that the heat absorbed thereby in the quenching will produce the desired temperature in the slurry according to the principles hereinbefore described, the necessary temperatures being determined according to the formula hereinbefore given. Such two methods of controlling the temperature of the slurry will frequently be combined, the temperature being controlled, in part, by absorption of heat by the ethyl chloride to raise its temperature and, in part, by the application of a separate cooling fluid.

When the slurry is to be conducted directly from the quenching chamber to a reaction chamber for reaction to make tetraethyl lead, the temperatures will usually be controlled so that the slurry has a temperature of from about 50 C. to 90 C., and, preferably, a temperature of from about 50 C. to about 60 C. The induction periods at these temperatures are sufficiently long to permit the slurry to be conducted to the reaction chamber while the alloy particles are still bright and before reaction takes place, since such conduction can usually be accomplished readily in from about 1 to about 5 seconds. Preferably, the reaction, between the alloy and the ethyl chloride to produce tetraethyl lead, will be carried out at temperatures of from about 85 C. to about 95 C.

and, if the slurry is at a lower temperature when it reaches the reaction chamber, it will be heated therein to such reaction temperature.

Also, in the continuous process, it is preferred to employ a circular quenching chamber and to inject the ethyl chloride therein in one or more high velocity streams tangent to the quenching chamber. It is also preferred to use from about 2 to about 9 parts by weigrt of ethyl chloride to each part of alloy, and, particularly, from about 2 to about 6 parts of ethyl chloride, so as to provide slurries containing from about 14% to about 33% alloy and which are sufficiently fluid to tlow readily through pipes to the separating equipment or the reactor. Furthermore, it is preferred to regulate the velocity of the ethyl chloride so as to produce slurries in which the alloy has a particle size of from about 8 mesh to about 40 mesh, especially from about 10 mesh to about mesh, as such slurries have particularly desirable flow characteristics. Also, it is preferred to employ an orifice of less than Vs inch in diameter for forming the stream of molten alloy to be injected into the ethyl chloride.

The temperature of the A representative type of apparatus, which .I'havefouncl to be particularly eflective for carrying out the continuous process, is shown in the accompanying drawings in which:

Fig. '1 isa somewhat diagrammatic view of one suitable form of apparatus for the continuous production of a slurry of lead-sodium alloy in ethyl chloride and passing it to a reactor for the continuous manufacture of tetraethyl lead;

Fig. 2-is a vertical sectional view of the quenching apparatus; and

Fig. 3 is an enlarged horizontal sectional view taken on line 33 of Fig. 2, with parts broken away for clearness of illustration.

Referring first to Figure l, a quenching chamber 10 is connected at its lower end with a pipe 12 for conducting the slurry into the reactor 14. The reactor is provided with a jacket 16, having an inlet 18 and an outlet 20, for circulation of a heat exchange fluid over the outer surface of the reactor. At the exit end of the reactor, there is a pipe 22, provided with a valve 24, for discharge of the heavy products of the reaction mixture to the receiver and a pipe 26, provided with a valve 28, for drawing off excess ethyl chloride and passing it to the receiver 30.

Referring more particularly to Figures 2 and 3, the quenching chamber 10 is in the form of a cone having its apex at the bottom. As shown, the quenching chamber is about 6 inches in height and has an internal diameter of about 4 inches at its upper end 32 and an outlet 34 about /4 inch in diameter. The quenching chamber is provided with a flange 36 at its lower end which is bolted to the flange 38 at the upper end of the pipe 12. The quenching chamber is also provided with a flange 40 at its upper-end which is bolted to a flange 42 at the lower end of a housing 48. A liquid ethyl chloride'supply pipe 44 is provided adjacent the upper end of the quenching chamber and terminates in three small ports 46 at its junction with the inner wall of the cone. The ethyl chloride supply pipe 46 is positioned tangentially to the inner surface of the cone and the ports 46 are arranged with their centers in a line corresponding to a generatrix of the cone, as is particularly shown in Figure 3.

The valve and nozzle assembly for feeding alloy to the quenching chamber comprises a vertical cylindrical housing 48 having its axis positioned to one side of the axis of the quenching chamber 10. A nozzle 50 is positioned coaxially of the housing 48, for feeding molten alloy to the quenching chamber. Such nozzle 50 terminates at its lower end in a restricted orifice 52 which, as shown, has a diameter of about inch. The nozzle is also provided with a rod 54 secured to the lower end of the valve 56. The rod 54 has a diameter materially less than the bore of the nozle but slightly greater than the orifice 52, and a lower end of reduced diameter slightly less than the diameter of the orifice 52. The rod 54 is provided so that, when the valve is closed, the lower end of the rod will pass through the orifice 52 and close such orifice, but, when the valve is opened, the rod is moved out of the orifice so as to permit flow of molten alloy therethrough. This rod is provided primarily for removing any material which may clog the orifice, in whole or in part, during operation which is accomplished by mementarily closing the valve, thus forcing the rod through the orifice and pushing any obstruction before it.

The valve 56 is provided, at its upper end, with a handwheel 58 for operation of the valve. The valve 56 is also threaded, at its upper end, to engage corresponding inner threads in the upper end of the valve bonnet 60. The valve bonnet contains packing material 62 and a packing gland 63 regulated by a packing nut 64. The lower end of the valve 56 engages the valve seat 66 at the upper end of the nozzle 50. A disc 68 is secured to the upper end of the nozzle 50 and surrounds the lower end of the valve 56. Such discis provided with a central ing examples are given:

; funnel having a inch orifice.

enlarged valve chamber 70 connecting with the bore of the nozzle 50. The disc also has an inlet 72 extending through one side thereof into the valve chamber 70, which inlet 72 is connected at its outer end with a molten alloy supply pipe 74. The housing 48 is provided at its upper end with a flange 76 which is bolted to a flange 78 at the lower end of the valve bonnet 60 for securing the housing 48, the disc 68 and the valve bonnet 60 together.

A nitrogen supply pipe 80 is connected with the housing 48 near the lower end thereof and adjacent the orifice 52. As shown particularly in Figure 3, the nitrogen supply pipe 80 is connected with the housing 48 so as to direct the nitrogen substantially tangentially of the inner surface of the housing 48. Preferably, the nozzle 50 is heated inductively by an alternating current flowing through a winding (not shown) outside the housing 48 so as to prevent freezing of the molten alloy in the nozzle.

In operation, liquid ethyl chloride at the desired temperature is injected under pressure into the quenching chamber through pipe 44 and ports -4 6 to form a rapidly whirling vortex of liquid ethyl chloride of appreciable depth, preferably, filling the cone to a depth of from about /2 to about of the distance from the outlet 34 to the ports 46. With a cone quenching chamber of the dimensions hereinbefore given, the liquid ethyl chloride must be fed at the rate of at least 6.6 pounds per minute in order to provide and maintainthe desired vortex. The ethyl chloride may be fed at a rate of from 6.6 pounds per minute to about 12 pounds per minute but, preferably, is fed at a rate of from 6.6 pounds per minute to about 10 pounds per minute. While not necessary, it is generally preferred to introduce an inertrgas, such as nitrogen or helium, under pressure through the pipe 80 so as to provide an inert atmosphere in the pipe 48 and prevent contact ofthe hot molten alloy with va ors of ethyl chloride in this region and to maintain the desired pressure in the quenching chamber.

After the vortex of liquid ethyl chloride has been established in the quenching chamber 10, the valve 56 is opened and molten alloy is introduced through pipe 74, inlet 72, nozzle 50 and orifice ,52, whereupon it drops into the rapidly whirling vortex of. liquid ethyl chloride to one side of the center of 'the vortex and is substantially passes through the pipe 12 and into the reactor 14 ina period of from about 1 to about 5 seconds. In order to more clearly illustrate myinvention, preferred modes of carrying the same into eifectfand the advantageous results to be obtained. thereby, the follow- .Example 1 A one liter round-bottomed flaskwas provide d with a paddle stirrer, a-reflux condenser cooled to 60 C having a drying tube at its upper end, and a heated'dropping 400 grams of ethyl chloride were placed in the flask and maintained at a temperature of about 13 C. by refluxing. The refiuxing of the'ethyl chloride displaced all oxygen and water vapor from the flask and condenser and maintained an atmosphere ofethyl chloride therein.- 60 grains of lead-sodium alloy, containing 10% by weight of sodium,

-was added to the dropping funnel and melted, while being protected by a blanket of dry'nitrogen- Theliquiid ethyl chloride was stirred rapidly to give it a linear velocity of about 250 feet per minute directly underthe end of the "dropping'funnel which .was about '4 inches above the.

surface of the liquid. The molten'alloy, at a'temperatur'e of from about 375 C.' to about 400 C., was dropped into the agitated liquid ethyl chloridein a slow stream during a period of about 0.5 minute. When the addition of the alloy wascompleted, the stirring was stopped, the alloy particles settled, the layer of liquid ethyl chloride decanted off, and the remainder of the ethyl chloride removed by evaporation in a stream of dry nitrogen. The alloy particleswere bright in appearance and of a uniform particle size of about 40 mesh. By increasingthe linear velocity of the liquid ethyl chloride to 500 feet per minute, alloy of a uniform particle'size of about 100 meshwas obtained. When the velocity of the ethyl chloride was decreased to 50 feet per minute, the alloy had a uniform particle size of about 8 mesh.

In order to test the suitability of alloy for making tetraethyl lead, cooled tared bombs Were flushed with dry nitrogen, and then, while preventing contamination with air or moisture, 300 grams of ethyl chloride, containing 0.1% of acetone as a catalyst, and 50 grams of alloy were added to the bombs and the bombs immediately sealed. The bombs were. quickly heated to reaction temperatures of from C. to 100 C. with agitation, usually by rotating the bombs at about 36 revolutions per minute. When the heating had been conducted for the desired period of time, the reaction was stopped, usually by plunging the bomb into a bucket of ice, the bomb opened, and the contents separated and analyzed to determine the percent yield of tetraethyl lead based on the amount of alloy used.

When the alloy, prepared as described in the first paragraphof this Example 1, was so tested, it produced from about 82% to about 89% yields of tetraethyl lead (an average yield of about 85%) when heated for 5 minutes at reaction temperatures of 85 C. and 90 C. Variation of the particle size of the alloy, between 8 mesh and mesh, produced little or no change in the yield of tetraethyl lead. I

Example 2 Lead-sodium alloy, containing 10% by weight of sodium, was quenched in ethyl chloride in the apparatus shown in the accompanying drawing, provided with means (not shown) for taking samples of the slurry issuing from the quenching chamber. Liquid ethyl chloride, at a temperature of 32 C., was pumped under pressure into the quenching chamber at the rate of 9.9 pounds per minute. Molten alloy, at a temperature of 450 C., was injected under pressure through the nozzle into the quenching chamber and into the whirling body of ethyl chloride at the rate of 3,14 pounds per minute. Nitrogen under pressure was introduced in a slow stream suflicient to maintain a nitrogen atmosphere above the whirling body of ethyl chloride and, particularly, around the nozzle and tip, and passed through the outlet with the slurry. The absolute pressure in the quenching chamber was maintained at about pounds per square inch, which was sufiicient to prevent vaporization of the ethyl chloride. The total time of the alloy in the quenching chamber was estimated at less than one second.

The resulting slurry'had a temperature of 57 C. and

contained 24% by weight of alloy inthe form of small spherical or ovaloid particles which were bright and reactivity similar to that of Example '1.

The slurry passed fromthe quenching chamber to the reactor in from about 1 to about 5 seconds and while the alloy particles were still bright and silvery in appearance. The slurrywas retained in the reactor and heated to about 90 C. for the rest of the induction period and until substantially allof the alloy was consumed by reaction with the ethyl chloride. The reaction mass issued from the reactor continuously and was passedto the receiver for recovery of; the tetraethyl lead, sodium chloride, ethyl chloride, and metallic lead. I

The process .of Example .2 was repeatcdmany times,

varying the alloy feed rate over the range of from 2.25

to.3.'7 pounds per minute and the ethyl chloride feed rate over the range of from 7.7 to 8.6 pounds per minute to produce slurries containing from 20.7% to 31.1% by weight of "alloy; and also varying the alloy feed rate over the range of from 1.9 to 2.2 pounds per minute and the ethyl chloride feed rate over the range of from 10.1 to 6.6 pounds per minute to produce slurries containing from 15.8% to 25% by weight of alloy. Such slurries gave yields of tetraethyl lead of from 74.5% to 92% in 3 to l7'minutes at 90-C. in the presence of 0.1% of acetone based on the ethyl chloride, an average yield of about 83%.

Example 3 Commercial lead-sodium alloy, containing 10% by *weight of sodium, was sieved under nitrogen to obtain a fraction having a particle size of 10 to 16 mesh. When tested with ethyl chloride, containing 0.1% acetone, at 90 C. by the procedure of Example 1, the yields of 'tetr-aethyl lead were 74% to 81%in 5 minutes and 83.5%

to 90% in '15 minutes. The alloy, which passed through the 16 mesh screen, gave tetraethyl lead yields of about 21% in minutes under the same conditions. The original unsieved alloy gave yields of tetraethyl lead averaging about 76% in 15 minutes under such conditions.

Example 4 Equal quantities of molten lead-sodium alloy, containing 10% by weight of sodium, were put into three bombs, two of which had been previously filled with clean steel ball bearings, and solidified. The bombs, containing the ball bearings, were rotated for 16 hours in order to cause the ball hearings to grind the solidified a1 loy. lt was found that this reduces most of the alloy to a fine powder but leaves about 10% not ground. Equal quantities of ethyl chloride, containing 0.1% acetone, Were then added to the three bombs and the bombs heated to 90 C. for five minutes. The alloy, ground by the ball bearings, gave yields of 70.35% and 56.4% tetraehyl lead. The unground alloy gave a yield of 86.5% tetraethyl lead.

Example 5 Samples of finely divided lead-sodium alloy, containing 10% by weight of sodium, were prepared by grinding commercial alloy in a micropulverizer while being blanketed under protective atmospheres of helium, dry

nitrogen, and ethyl chloride, respectively. About 89% of the alloy, so ground, could be passed through a 250 mesh screen. When tested under the conditions of Example 3, the alloy ground under helium gave yields of 13% to 31.2% tetraethyl lead; that ground under nitrogen gave yields of 22.9% to 35.5% tetraethyl lead; and that ground under ethyl chloride gave yields of 62.3% to 75.2% tetraethyl lead. When the reaction time was re- .duced to 5 minutes with the alloy ground under ethyl chloride, the yields of tetraethyl lead were-47.1% to 50%.

Examples 3, 4 and 5 are included for purposes of comparison.

It will be understood that the preceding examples have been given for illustrative purposes solely and that my Y invention is not limited to the specific embodiments disclosed therein, but that I intend to cover my invention broadly as in the appended claims. It will be readily apparent to those skilled in the art that many variations and modifications may be made in the methods and apparatus for carrying out the process of my invention. It will be particularly apparent that the apparatus, shown in the drawings, may be widely varied in .size and in construction. :Furthermore, the proportions and conditions of operationmaybe widely varied within the ranges.

12 broadly disclosed without departing from the spirit .or scope of .my invention.

It will be seen that my invention provides a novel method for preparing lead-sodium alloy in a. form which is peculiarly adapted for use in the manufacture of tetraethyl lead. My process is far more simple and requires less elaborate and costly equipment than the process previously employed, whereby the alloy may be prepared in desired form .much more readily and economically. By my process, the alloy can be obtained in particles of uniform and controlled size which are materially more reactive toward ethyl chloride and produces higher yields of tetraethyl lead than alloy obtained by the prior processes. Furthermore, my process can be operated most readily in a continuous manner particularly for the production of a slurry of alloy in ethyl chloride which is well adapted for use in the continuous manufacture of tetraethyl lead. Also, my process avoids contact of the .hot alloy with tetraethyl lead and thus eliminates danger of explosions from such cause. Therefore, it will be apparent that my invention constitutes a very valuable and important improvement and advance in the art.

I claim:

1. The process which comprises passing a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 -C. to about 750 C. through an orifice of less than /2 inch in diameter and then into a violently agitated body of liquid ethyl chloride maintained at a temperature offromabout 50 C. to C. in a quenching :chamber, employing about 1 part of alloy to from 9 parts to 1 part by weight of ethyl chloride and forming a slurry of unreacted alloy in ethyl chloride in which the alloy is in the form of brightsolid particles up to about 8 mesh in size.

2. The process which comprises passing a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than 6 inch in diameter and then into a violently agitated body ofliquid ethyl chloride maintained at a temperature of from about -50 C. to +90 C. in a quenching chamber, employing about 1 part of alloy to from 9 parts to 1 part by weight of ethyl chloride and forming a slurry .of unreacted alloy in ethyl chloride in which the alloy is in the form ofbright solid particles of from about 8 mesh to about mesh in size, and then removing at least the solid alloy particles from the quenching chamber while theyare still bright.

3. The process which comprises passing a stream of molten leadrsodium .alloy, containing from 9.9% to 10.1% by weight .of sodium, at a temperature of from about 370 .C. to about 750 C. through an orifice of less than /2 inch in diameter and then into a violently agitatedbody of liquid ethyl chloride maintained at a temperature of from about -50 C. to +90 C. in a quenching chamber, employing about 1 part of alloy to from 9 parts to 1 part by weight of ethyl chloride and forming a slurry of unreacted alloy in ethyl chloride in which the alloy is in the form of bright solid particles up to about-8 mesh .in size, and then separating the solid alloy particles from the ethyl chloride while they are still bright.

4. The process which comprises passing a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than /2 inch in diameter and then into a violently agitated body of liquid ethyl chloride maintained at a temperature of from about 50 C. to +90 C. in a quenchingchamber, employing about 1 part of alloy tofrom 9 parts to 1 part'by weight of ethyl chloride and adding the alloy at ;a rate such that all of it is passedinto the ethyl chloride ina period of time mate- .rially less than the induction period for the maximum temperature attained by the mixture, forming a slurry of 13 unreacted'alloy in ethyl chloride in which the alloy is in the form of bright solid particles of from about 8 mesh to about 100 mesh in size, then terminating the agitation and separating the solid alloy particles from the ethyl chloride while they are still bright.

5. The process which comprises passing a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than V2 inch in diameter and then into a violently agitated body of liquid ethyl chloride maintained at a temperature of from about 50 C. to about +30 C. in a quenching chamber, employing about'l part of alloy to from 9 parts to 1 part by weight of ethyl chloride and adding the alloy at a rate such that all of it is passed into the ethyl chloride in a period of time materially less than the induction period for the maximum temperature attained by the mixture, forming a slurry of unreacted alloy in ethyl chloride in which the alloy is in the form of bright solid particles of from about 8 mesh to about 100 mesh in size, then terminating the agitation and separating the solid alloy particles from the ethyl chloride while they are still bright.

6. The process which comprises passing a stream of molten lead sodium alloy, containing from 9.9% to l'.l% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than V: inch in diameter and then into a violently agitated body of liquid ethyl chloride maintained at a temperature of from about 50 C. to +90 C. in a quenching chamber, employing about 1 part of alloy to from 9 parts to 1 part .by weight of ethyl chloride and forming a slurry of unreacted alloy in ethyl chloride in which the alloy is in the form of bright solid particles up to about 8 mesh in size, and then passing the slurry to a reaction chamber while the solid alloy particles are still bright.

7. The process which comprises passing a stream of molten lead-sodium alloy, containing from 9.9% to 10.1 by weight of sodium, at a temperature of from about 370 C. to about 750 C.'through an orifice of less than /8 inch in diameter and then-into a violently agitated body of liquid ethyl chloride maintained at a temperature of from about 50 C. to +90 C. in a quenching chamber, employing about 1 part'of alloy to from 9 parts to 2 parts by weight of ethyl chloride and forming 21 slurry of unreacted alloy in ethyl chloride in which the alloy is in the form of bright solid particles of from about 8 mesh to about 100 mesh in size, and then passing the slurry to a reaction chamber while the solid alloy particles are still bright.

8. The process which comprises passing a stream of molten lead-sodium alloy, containing from 9.9% to 10.1 by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than A; inch in diameter and then into a violently agitated body of liquid ethyl chloride maintained at a temperature of from about C. to 90 C. in a quenching chamber, employing about 1 part of alloy to from 9 parts to 2 parts by weight of ethyl chloride and forming a slurry of unreacted alloy in ethyl chloride in which the alloy is in the form of bright solid particles of from about 8 mesh to about 100 mesh in size, and then passing the slurry to a reaction chamber while the solid alloy particles are still bright.

9. The process which comprises passing a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than Vs inch in diameter and then into a violently agitated body of liquid ethyl chloride maintained at a temperature of from about 50 C. to about 60 C. in a quenching chamber, employing about 1 part of alloy to from 9 parts to 2 parts by weight of ethyl chloride and forming a slurry of unreacted alloy in ethyl chloride 'in which the alloy is in the form of bright solid particles of from about 8 mesh to about 100'mesh in size, and then passing'the slurry to a reaction chamber While the solid alloy particles are still bright.

10. The process which comprises continuously introducing a high velocity stream of liquid ethyl chloride at a temperature of from about 50 C. to C. tangentially intoa quenching chamber having a restricted bottom outlet to form a rapidly whirling vortex of liquid ethyl chloride, injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than /2 inch in diameter and then into the body of ethyl chloride to one side of the center of the vortex in the proportion of about 1 part of alloy to from 9 parts to 2 parts by weight of ethyl chloride while maintaining the ethyl chloride in the liquid state at a temperature of from about -50 C. to C., and continuously removing the resulting slurry of solid alloy particles in ethyl chloride through the outlet substantially as fast as it is formed and while the alloy particles are still bright.

11. The process which comprises continuously introducing a high velocity stream of liquid ethyl chloride at a temperature of from about 50 C. to +80 C. tangentially into a quenching chamber having a restricted bottom outlet to form a rapidly whirling vortex of liquid ethyl chloride, injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than /s inch in diameter and then into the body of ethyl chloride to one side of the center of the vortex in the proportion of about 1 part of alloy to from 9 parts to 2 parts by weight of ethyl chloride while maintaining the ethyl chloride in the liquid state at a temperature of from about -50 C. to +90 C., and continuously removing the resulting slurry of alloy particles in ethyl chloride through the outlet substantially .as fast as it is formed, and separating the alloy particles from the ethyl chloride while they are still bright.

12. The process which comprises continuously introducing a high velocity stream of liquid ethyl chloride at a temperature of from about -50 C. to +80 C. tangentially into a quenching chamber having a restricted bottom outlet to form a rapidly whirling vortex of liquid ethyl chloride, injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than /2 inch in diameter and then into the body of ethyl chloride to one side of the center of the vortex in the proportion of about 1 part of alloy to from 9 parts to 2 parts by weight of ethyl chloride while maintaining the ethyl chloride in the liquid state at a temperature of from about 50 C. to +90 C., and continuously removing the resulting slurry of alloy particles in ethyl chloride through the outlet substantially as fast as it is formed, and continuously passing the slurry directly to a reaction chamber while the particles of alloy are still bright.

13. The process which comprises continuously introducing a high velocity stream of liquid ethyl chloride at a temperature of from about 50 C. to 80 C. tangentially into a quenching chamber having a restricted bottom out- 'let to form a rapidly whirling vortex of liquid ethyl chloride, injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperatue of from about 370 C. to about 750 C.

through an orifice of less than /2 inch in diameter and then into the body of ethyl chloride to one side of the center of the vortex in the proportion of about 1 part of alloy to from 9 parts to 2 parts by weight of'ethyl chloride while maintaining the ethyl chloride in the liquid state at a temperature of from about 50 C. to 90 C., and continuously removing the resulting slurry of alloy particles in ethyl chloride through the outlet substantially as 15 fast as it is formed, and continuously passing :the :slurry directly to a reaction chamber while the :particles of alloy are still bright.

14. The process which comprises continuously introducing a high velocity stream of liquid ethyl chloride at a temperature of from about -50 C. to +80 C. tangentially into a quenching chamber having a restricted bottom outlet to form a rapidly whirling vortex ofliquid ethyl chloride, injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than A; inch in diameter and then into the body of ethyl chloride to one side of the center of the vortex in the proportion of about .1 part of alloy to from 6 parts to 2 parts by weight of ethyl chloride While maintaining the ethyl chloride in the liquid state at a temperature-of from about -.50 C. to +90 C., and continuously removing the resulting slurry of alloy particles in ethyl chloride through the outlet substantially as fast as it is formed, and continuously passing the slurry directly to a reaction chamber while the particles of alloy are still bright.

15. The process which comprises continuously introducing a high velocity stream of liquid ethyl chloride at a temperature of from about 50 C. to 80 C. tangentially into a quenching chamber having a restricted bottom outlet to form a rapidly whirling vortex of liquid ethyl chloride, injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to about 750 C. through an orifice of less than A; inch in diameter and then into the body of ethyl chloride to one side of the center of the vortex in the proportion of about 1 part of alloy to from 6 parts to 2 parts by weight of ethyl chloride while maintaining the ethyl chloride in the liquid state at a temperature of from about 50 C. to 90 C., and continuously removing the resulting slurry of alloy particles in ethyl chloride through the outlet substantially as fast as it is formed, and continuously passing the slurry directly to a reaction chamber while the particles of alloy are still bright.

16. The process which comprises continuously introducing a high velocity stream of liquid ethyl chloride at a temperature of from about 20 C. to about 32 C. tangentially into a quenching chamber having a restricted bottom outlet to form a rapidly whirling vortex of liquid ethyl chloride, injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of 16 sodium, at a temperature of fromabout 370 C. to about 750 C. through an orifice of less than /8 inch in diameter and then into the body of ethylchloride to one side of the center of the vortex in the proportion of about 1 part of alloy to from 9 parts to 2 partsby'weight of ethyl chloride while maintaining the ethyl chloride in the liquid state at a temperature of from about 30 C. to about 65 C., and continuously removing the resulting slurry of alloy particles in ethyl chloride through the outlet substantially as fast as it is formed, and continuouslypassing the slurry directly to a reaction chamber while the particles of alloy are still bright.

17. The process which comprises continuously introducing a high velocity stream of liquid ethyl chloride at a temperature of from about 20 C. to about 32 C. tangentially into a quenching chamber having a restricted bottom outlet to form a rapidly whirling vortex of liquid ethyl chloride, injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, at a temperature of from about 370 C. to'about 750 C. through an orifice of less than A; inch in diameter and then into the body of ethyl chloride to .one side of the center of the vortex in the proportion of about 1 part of alloy to from 6 parts to 2 parts by weight of ethyl chloride while maintaining the ethyl chloride in the liquid state at a temperature of from about 30 C. to about 65 C., and continuously removing the resulting slurry of alloy particles in ethyl chloride through the outlet substantially as fast as it is formed, and continuously passing the slurry directly to a reaction chamber while the particles of alloy are still bright.

18. A process of making tetraethyl lead, which comprises quenching a molten lead-sodium alloy by introducing it into a body of cold liquid ethyl chloride held in a container at a temperature at which the ethyl chloride does not react with the quenched alloy in said container during the introduction of the molten alloy, and subsequently alkylating the lead of the unreacted, quenched alloy with liquid ethyl chloride.

References Cited in the the of this patent UNITED STATES PATENTS 1,306,060 Hall June 10, 1919 1,974,167 Voorhees Sept. 18, 1934 2,043,224 Amick et a1 June 9, 1936 2,109,005 Bake Feb. 22, 1938

Claims

3. THE PROCES WHICH COMPRISES PASSING A STREAM OF MOLTEN LEAD-SODIUM ALLOY, CONTAINING FROM 9.9% TO 10.1% BY WEIGHT OF SODIUM, AT A TEMPERATURE OF FROM ABOUT 370* C. TO ABOUT 750* C. THROUGH AN ORIFICE OF LESS THAN 1/2 INCH IN DIAMETER AND THEN INTO A VIOLENTLY AGITATED BODY OF LIQUID ETHYL CHLORIDE MAINTAINED AT A TEMPERATURE OF FROM ABOUT -50* C. TO +90* C. IN A QUENCHING CHAMBER, EMPLOYING ABOUT 1 PART OF ALLOY TO FROM 9 PARTS TO 1 PART BY WEIGHT OF ETHYL CHLORIDE AND FORMING A SLURRY OF UNREACTED ALLOY IN ETHYL CHLORIDE IN WHICH THE ALLOY IS IN THE FORM OF BRIGHT SOLID PARTICLES UP TO ABOUT 8 MESH IN SIZE, AND THEN SEPARATING THE SOLID ALLOY PARTICLES FROM THE ETHYL CHLORIDE WHILE THEY ARE STILL BRIGHT.
18. A PROCESS OF MAKING TETRAETHYL LEAD, WHICH COMPRISES QUENCHING A MOLTEN LEAD-SODIUM ALLOY BY INTRODUCING IT INTO A BODY OF COLD LIQUID ETHYL CHLORIDE HELD IN A CONTAINER AT A TEMPERATURE AT WHICH THE ETHYL CHLORIDE DOES NOT REACT WITH THE QUENCHED ALLOY IN SAID CONTAINER DURING THE INTRODUCTION OF THE MOLTEN ALLOY, AND SUBSE-