US2891977A - Process for producing tetraethyl lead - Google Patents

Description

, J1me 1959 Y G. F. SCHLAUDECKER 2,891,977

PROCESS FOR PRODUCING TETRAETHYL LEAD M Filed Oct. 4, 1955 GEORGEFSCHIA UDEOKEK 3- v ATTQRNEY United States Patent 2,891,977 PROCESSFOR PRODUCING TETRAETHYL LEAD George F. Schlaudecker, Toledo, Ohio, assignor to E. I. du Pont de Nernours and Company, Wilmington, Del.,

a corporation of Delaware Application October 4, 1955, Serial No. 538,330

11 Claims. (Cl. 260--437) This invention relates to a process for producing tetraethyl lead and, more particularly, to a continuous process therefor.

This application is a continuation-in-part of my copending application Serial No. 189,531, filed October 11, 1950, now abandoned, for Process for Producting Tetraethyl Lead.

Prior to my invention, the commonly employed methods for manufacturing tetraethyl lead and commercial lead-monosodium alloy for use therein have been by the batch process. The manufacture of the alloy has involved a complicated series of steps and complex equipment. Such steps include mixing molten sodium and molten lead to produce molten alloy, cooling and solidifying the alloy in thin layers, breaking up and grinding the solidified alloy, and loading it into closed hoppers for transportation to and connection with autoclaves, all in an atmosphere of nitrogen or other inert gas. Such processes and the apparatus employed are illustrated by Patent No. 2,043,224 of Amick et al., Patent No. 2,047,391 of Stecker et al., Patent No. 2,091,801 of Arnick et a1. and Patent No. 2,134,091 of Stecker.

The alloy is fed from the hoppers into the autoclaves where it is agitated and heated to temperatures of from about 45 C. to about 50 C. Ethyl chloride is then added to the 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 ethyl chloride with the leadsodium 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 60% excess. Care is taken to maintain the temperatures in the autoclaves below 100 C. because tetraethyl lead tends to decompose rapidly at temperatures slightly above 100 C., and with explosive violence at materially higher 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.

The prior processes of preparing the alloy andtransporting it to the autoclaves are expensive 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 with ethyl chloride. Furthermore, because of the physical condition of the alloy and its slow reactivity, it has been necessary to carry out the reaction with ethyl chloride in batches and to add the alloy to the autoclave prior to the addition of the ethyl chloride. A satisfactory method of adding such solid alloy continuously to a reactor, containing ethyl chloride under pressure, is not known. Such batch operation of. the autoclaves is expensive and time consuming because each charge must be maintained in the autoclave for about 2 to 4 hours, and considerable time and expense is involved in discharging the reaction mass 2,891,977 Patented June 23, 1959 I pedients have resulted in alloy of greatly decreased reactivity and the production of low yields of tetraethyl lead.

Voorhees, in Patent No. 1,974,167, has proposed the manufacture of gasoline containing lead-hydrocarbon compounds by atomizing molten lead-sodium alloy and dropping it into and through chlorinated gasoline maintained at 300 F. to 600 P. (148.89" C. to 315.56 0.), whereby the alloy is solidified and reacted with the chlorinated hydrocarbons. He thereby obtains complex leadhydrocarbon compounds, other than tetraethyl lead, which are less effective than tetraethyl lead as anti-knock agents. Such process is impractical because it involves the treatment of objectionably large volumes of material at temperatures of at least 300 F., requiring large and ex-- pensive equipment, and the reaction with the chlorinated hydrocarbons in such dilute solution is incomplete so that the resulting gasoline will contain large amounts of corrosive chlorinated compounds. His lead-hydrocar- 'bon compounds are present in extremely low concentrations, about 0.2% to about 0.4%, so that there is little opportunity for contact thereof with the hot alloy and consequent explosive decomposition. Apparently,. such process of Voorhees has never been used commercially.

It is an object of this invention to provide an improved process for preparing tetraethyl lead in a simple and economical manner which requires relatively simple and inexpensive equipment and overcomes the disadvantages of the prior art processes. A particular object is to provide an improved process for the continuous manufacture of tetraethyl lead. A further object is to provide a continuous process for preparing a suspension of leadsodium alloy in ethyl chloride and, substantially simultaneously, reacting the alloy and the ethyl chloride continuously in a continuous process for making tetraethyl lead. A still further object is to advance the art. Other objects will appear hereinafter.

The above and other objects maybe accomplished in accordance with this invention which comprises continuously injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal reaction zone maintained under reaction conditions and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.5 to about 4 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the resulting suspen: sion lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it under reaction conditions until the reaction is substantially complete, continuously removing'the resultant reaction mixture from the reaction zone through the discharge end thereof, and thereafter separating the tetraethyl lead from the reaction mixture.

It is Well known to the art that lead-sodium alloy reacts with liquid ethyl chloride to produce tetraethyl lead 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. Also, lead-sodium alloy reacts with ethyl chloride in the vapor phase to pro duce hydrocarbons instead of tetraethyl lead. 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 vaporization of ethyl chloride and reac tion to produce hydrocarbons. Also, if some of the molten alloy should react with liquid ethyl chloride to form tetraethyl lead, it would be expected 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, it has been found that such expected results are not obtained if the addition of the molten alloy to the suspension or to liquid ethyl chloride is accomplished under properly con trolled conditions.

It has been found that, when streams of molten alloy and liquid ethyl chloride, in the proportions of this invention, are injected into a horizontally flowing body of rapidly agitated suspension of such alloy in liquid ethyl chloride maintained under reaction conditions at temperatures up to about 120 C., the alloy is solidified and cooled to the temperature of the suspension (quenched) in less than 1 second and, probably, less than 0.1 second. It has also been found that under the conditions of this process, the suspension may contain tetraethyl lead in a proportion of up to at least by Weight based on the ethyl chloride at the point of injection of the molten alloy without causing appreciable decomposition of the tetraethyl lead or an explosion.

In order to carry out the process successfully, it is necessary that the alloy and the liquid ethyl chloride be caused to react in an elongated horizontal reaction zone with the reacting suspension flowing lengthwise of said zone, that is, the gross flow of the body of reacting sus pension must be in a horizontal direction. When it was attempted to carry out the process in a vertical reactor with molten alloy entering the top and with high velocity upward vertical flow of dilute reaction mixture for the purpose of suspending the alloy while it reacted and of causing the reaction products to overflow from the top of the reactor, it was found that the reacting alloy settled to the bottom of the reactor where it reacted, expanded, and tightly plugged and filled the bottom of the reactor, whereby the process could not be operated successfully. Also, when it was attempted to carry out the process in a series of pots provided with high speed propeller-type stirrers wherein liquid ethyl chloride and molten alloy were introduced into the first pot and the reacting suspension was supposed to flow out of side outlets near the tops of the successive pots, it was found that the process could not be made to operate successfully because the alloy built up in the first pot and collected in the bottom thereof and tended to solidify in a hard mass there.

Usually, the process is started by placing a body of liquid ethyl chloride in the reaction zone and subjecting it to the temperatures, pressures and agitation to be employed in the operation. Then the streams of molten alloy and liquid ethyl chloride are injected into the reaction zone and into such body of ethyl chloride at a rate of from about 1.5 to about 4 parts by weight of ethyl chloride for each part of alloy, whereby they mix and form a suspension of 1 part of alloy in from about 1.5 to about 4 parts by weight of ethyl chloride. Thcrefore, except at the start of the operation, the streams of alloy and ethyl chloride are injected into such suspension. The alloy, as so formed, is in a finely divided and unusually reactive condition so that it quickly and rapidly reacts with the ethyl chloride to form tetraethyl lead. Such reaction starts within one minute at 80 C., in about 0.5 minute at 90 C., and substantially instantaneously at 100 C.

and above. Therefore, the streams of ethyl chloride and molten alloy will usually enter a suspension which is reacting and which contains a small amount of tetraethyl lead, especially under the preferred conditions of operation.

The streams of molten alloy and liquid ethyl chloride are injected into the suspension at a point remote from the discharge end of the reaction zone, preferably near each other, and the reacting suspension is caused to fiow lengthwise of the reaction zone toward the discharge end thereof until the reaction is substantially complete, usually from about 5 to about 15 minutes; that is, the rate of flow of the suspension through the reaction zone is regulated so that each increment of the suspension is retained in the reaction zone until it is substantially completely reacted. The rate of flow of the reacting suspension, required to retain it in the reaction zone for the desired period of time, is dependent upon the design and construction of the reaction chamber, such as size and shape, and is specific to each reaction chamber. Such rate of flow can be readily calculated or otherwise determined by those skilled in the art, and will determine the rate of injection of the alloy and ethyl chloride streams.

The reaction mixture flowing from the reaction zone is a suspension of finely divided metallic lead and sodium chloride in a mixture of ethyl chloride and tetraethyl lead. It is conveyed to a receiver which may be an intermediate storage vessel supplying a separation and recovery system, or a continuously operated still or series of stills for separating and recovering the reaction products. Methods and apparatus for separating the products are Well known and conventional and form no part of this invention.

The temperature of the reacting suspension should be maintained at from about C. to about 120 C., and, preferably, at from about 100 C. to about 120 C. At temperatures materially below 80 C. there is a considerable delay in the start of the reaction, the reaction rate is slower, and the yield of tetraethyl lead is decreased. At temperatures materially above about 120 C., there is danger of decomposition of the tetraethyl lead and explosions.

Since the reaction is exothermic, the temperature is most readily controlled by refluxing the ethyl chloride at a controlled pressure corresponding to the temperature desired. For example, in order to maintain the suspension at temperatures of 80 C., C., C., C. and C., the pressures in the reaction chamber will be about 107, 137, 170, 210 and 255 pounds per square inch absolute, respectively. However, the temperatures may be controlled, in part, by the application of external cooling to the reaction chamber, and such external cooling will frequently be desirable when the reaction chamber is operated at maximum capacity with maximum concentration of alloy in the suspension.

The alloy melts at about 366 C. The molten alloy, injected into the suspension, may have a temperature of from about 370 C. to about 750 C., and, preferably, from about 400 C. to about 450 C. Since the alloy has a heat capacity of 0.056 calories per gram per degree C. and a heat of fusion of 8.1 calories per gram, only a relatively small amount of heat is introduced into the suspension by the cooling and freezing of the alloy. Such small amount of heat will have little effect on the temperatures of the ethyl chloride and of the suspension because the ethyl chloride has a heat capacity of 0.368 calory per gram per degree C.

The stream of ethyl chloride, injected into the reaction zone and into the suspension, should be at a temperature below the temperature of the reaction zone, and may be at a temperature as low as 20 C. so as to absorb some of the initial heat of the reaction and aid in the control of the temperature of the suspension.

The size of the particles of alloy in the suspension is dependent, mainly, upon the violence with which the suspension and the stream of molten alloy come into contact and, to a lesser extent, upon the dimensions of the stream of alloy. The stream of molten alloy introduced may be given various forms by means of the orifices and nozzles through which it is introduced. Thus it may be a continuous stream of round or elongated cross section or may be partly or completely separated into particles to form a spray. The thicker the continuous stream, the greater the agitation required to break it up into small particles on'reaching the suspension, the spray requiring little or no such agitation. Thus when using a continuous, stream, it is usually most convenient to have the shortest dimension of its cross section less than /2 inch and preferably between A5 and inch. Still smaller sizes may be used but clogging of the orifice begins to be a factor. The input of alloy may be in more than one stream.

The alloy feeding means, such as a. nozzle, must be heated and may be located either above, below or at the level of the suspension in the reaction zone. It is usual- 'ly most convenient to locate the nozzle above the -level of the suspension so as to avoid cooling of the nozzle and possible freezing of the alloy therein. However, it is sometimes more convenient to inject the stream of molten alloy through a nozzle which is below the level of or submerged in the suspension. The amount of heat, which must be put into a submerged nozzle in order to prevent alloy from freezing in it, will be somewhat greater than with a nozzle which is located above the suspension. However, such greater amount of heat is not prohibitive because of the well-known phenomenonv of film boiling whereby a complete and continuous layer of vapor is formed and maintained between -a heated surface and an adjacent volatile liquid when said surface is maintained'at a temperature of 50 C. or more above the boiling point of the liquid. See Heat Transfer in Forced Convection Film Boiling, by Bromley et -al., Ind. and Eng. Chem., December 1953, pages 2639-2646. Such layer of vapor prevents direct contact of the liquid with the heated surface and, since the vapor is a poorer conductor of heat than the liquid, the loss of heat from the submerged nozzle will be less than if the nozzle were in direct contact with the liquid.

Since the alloy is considerably heavier than the ethyl chloride, rapid agitation 'is necessary to maintain the particles in suspension so that the suspension can flow uniform-1y through the reaction zone and so'that the reaction mixture, which contains particles of metallic lead and sodium chloride, can be continuously withdrawn through the discharge end of the reaction zone. The agitation, required-to maintain the particles-in suspension,

also serves to break up the entering stream of molten alloy. Variation in the size of the particles, as so'produced, does notappear to materially affect the activity of the alloy or the speed of the reaction. The agitation required is dependent, mainly, upon the design, construction and efficiency of the equipment employed and, par ticularly, of the reactor and the agitating means. In any particular case, however, the operator can readily determine whether the rate of agitation is sufiicient by observing whether the suspension is maintained and regulating the agitation accordingly. The maximum rate of agitation will be limited by the capacity of the agitating means and by economic considerations, greatly excessive agitation resulting in waste of power and in more rapid wearing out of the equipment.

The streams of ethyl chloride and molten alloy should be regulated so as to provide from about 1.5 to about 4 parts by weight of ethyl chloride to each part of alloy and, preferably, fromabout 1.8 to about 2.3 parts by 35% to about 3.0% by weight. The use of more dilute suspensions, while operable, reduces the amount of tet- 6 raethyl lead produced by the equipment without increasing the yield based on the alloy, and is relatively uneconomical. Suspensions, .containing materially more than 40% by weight of alloy cannot be agitated efiiciently, particularly when partly converted to their reaction products.

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 highest yields, and that very slight variations in the composition of the alloy seriously decrease its efficiency 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 lead-sodium alloy, containing from 9.9% to 10.1% by' weight of sodium, may be used effectively in my process and will show equal reactivity toward ethyl chloride. Materially wider variations in thecomposition 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 composition of the alloy, whereby alloy of maximum efliciency can be manufacturedmore easily and economically.

The ethyl chloride 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, 2,477,465 and 2,515,821. 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 reduces the time required for completion of the reaction and helpsto prevent agglomeration and balling of the solid reaction products, whereby discharge of the suspension from the reaction chamber and subsequent separation of the tetraethyl lead are facilitated.

It is well known that lead-sodium alloy is reactive to oxygen and moistureand 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 reaction zone, the alloy is conventionally protected by an atmosphere of such an inert gas. In the reaction zone, the alloy is protected by liquid ethyl chloride and vapors thereof above the liquid.

While many different types of reactors may be used in carrying out my process, it'has' been found that a horizontal tubular reactor is far superior to other forms. Apreferred form of such horizontal tubular reactor is shown in the accompanying drawings, in which:

Figure 1 is a somewhat diagrammatic view in elevation of the reactor, the feedingmeans and the receiver;

Figure 2 is a longitudinal vertical sectional view of the reactor and thefeeding means; and

' Figure 3 is a vertical sectionalview through the re-' actor taken on line 33 of Figure 2.

The reactor comprises a horizontal cylindrical reaction chamber 10 about 15 inches in diameter and about 45' inches long. The inletend of the reactor is closed by a plate 12, provided with a central stufling box 14, and packing 16 for the agitator shaft 18. The exit end of the reactor is closed by an outlet cover 20, provided at its center with a stufling box 22 and packing24 for the agitator shaft 18. The outlet cover 20 is provided with a flange 26 which is adapted to be secured to a flange 28 at the end of the wall of the reaction chamber.

The reaction chamber is provided with a jacket 30,

The reaction chamber 10 is provided at the bottom near its outlet end with a discharge outlet 41 for discharging the contents of the reactor through a valved pipe 42 into a suitable receiver 44. The outlet 41 is provided primarily for draining and cleaning the reactor, but may also be employed for supplemental continuous removal of the reaction mixture. The upper portion of the outlet cover is provided with an overflow outlet 46 for continuous discharge of the reaction mixture through valved pipe 48 into receiver 44. The outlet cover 20 may be rotated and secured to the end of the reaction chamber 10 in the desired rotated position so as to adjust the height of the overflow outlet 46 and thus maintain the desired liquid level in the reactor.

At the inlet end, the reactor is provided with a charging stack 50 having a bulls eye sight glass 52. A pipe 54 is provided for the return of liquid ethyl chloride from the reflux condenser to maintain the proportion of ethyl chloride to solids and to aid in the control of the temperature. flange 56 to which is secured a flange 58 of the feeding means.

The feeding means comprises a vertical pipe 60, having a downwardly extending skirt 62 terminating a short distance above the sight glass 52, and a nozzle 64 which is provided at its lower end with a restricted orifice about inch in diameter. The lower end of the nozzle is well above the lower end of the skirt 62. The nozzle 64 is coaxial with the pipe and is surrounded by suitable heat insulating material 66. Preferably, the nozzle is heated to the temperature of the molten alloy by means of an induction coil, not shown, surrounding the pipe 60. The nozzle is provided with a rod 68 secured to the lower end of the valve 70 operated by a valve handwheel 72. The rod 68 has a diameter materially less than the bore of the nozzle but slightly greater than the restricted orifice, and a lower end of reduced diameter slightly less than the diameter of the orifice. The rod 68 is provided so that, when the valve is closed, the lower end of the rod will pass through the orifice to close it, but, when the valve is opened, the rod is moved out of the orifice so as to permit flow of molten alloy through the orifice. This rod is provided primarily for removing any material which may clog the orifice, in whole or in part, during operation, by momentarily closing the valve and forcing the rod through the orifice to push any obstruction down through the orifice. The molten alloy is supplied under pressure by pipe 74 and flows through the valve chamber containing the valve 70 and through nozzle 64.

A pipe 75 is provided for introducing a stream of fresh liquid ethyl chloride under pressure. The inlet end of the pipe 75 is positioned tangentially to the inner surface of the pipe 60 below the lower end of the nozzle 64. Thereby, the stream of fresh liquid ethyl chloride is injected tangentially of the pipe 60, flows over the inner surface of the pipe 60 and down into the reaction mass, while the stream of molten alloy falls through the center of the stack and into the reaction mass, usually, without touching the walls of the pipe 60. However, if the orifice of the nozzle 64 should become slightly clogged so that the stream of alloy deviates from the center and toward the walls of the pipe 60, the layer of ethyl chloride, flowing on the surface of the inner walls of the pipe 60, will tend to reduce solidification of the alloy upon the inner surface of the pipe 60 and will also wash away any spray from the reaction mass. The skirt 62 further operates to prevent contact of molten alloy with the walls of the stack 50. Any deviation of the molten alloy stream or decrease in its flow can be readily observed through the sight glass 52.

The agitator shaft 18 is supported in bearings 76 and 73 and is operated by sheaved pulleys 80 and 82 operatively connected by belts 84, the sheave 32 being rotated by a motor 86. The shaft 18 carries a flat blade 88 turned at an angle to the axis of the shaft so as to The top of the stack 50 is provided with a tend to force the reaction mixture toward the outlet end of the reactor. The shaft 18 also carries a squirrel-cage agitator which comprises a plurality of longitudinal blades 90 extending from the stack 50 to the outlet end of the reactor, carried on spiders 92 attached to the shaft 18. Such blades 90 have their surfaces parallel to the axis of the shaft but are positioned to make an angle of 45 with the inner surface of the cylindrical walls of the reactor. These blades cause good agitation solely in a plane perpendicular to the axis of the reactor and do not cause any circulation of the reaction mixture in a direction away from the outlet end of the reactor.

In operation, the reactor will be flushed out with an inert gas, such as nitrogen or ethyl chloride vapor. Liquid ethyl chloride will then be introduced through pipe 75 while passing a heating fluid through the jacket until the reactor is filled to the desired level with a body of liquid ethyl chloride at the desired temperature and the system is otherwise filled with vapors of ethyl chloride under the desired pressures. The agitator is started and then the valve 70 is operated to inject the stream of molten alloy at the desired rate and the desired proportion relative to the stream of ethyl chloride injected through the pipe 75. As soon as the process is well started, the flow of heat exchange fluid through the jacket is stopped and, if desired or necessary, a cooling fluid is substituted. Throughout the operation, ethyl chloride is vaporized, enters the vapor dome where it is separated from solid and liquid spray, passed to a reflux condenser, condensed and returned to the inlet end of the reactor. The return of the condensed ethyl chloride maintains the desired proportion of ethyl chloride to solids in the suspension and greatly aids in the control of the temperature.

In order to more clearly illustrate my invention, preferred modes of carrying the same into effect and the advantageous results to be obtained thereby, the following examples are given:

Example 1 The apparatus, shown in the drawings and hereinbefore described, was filled to about 92% of its capacity with liquid ethyl chloride which was heated to 90 C. and agitated. Then, molten lead-sodium alloy, containing 10.0% by weight of sodium, at a temperature of 400 C. was injected under pressure through the nozzle into the reactor at a rate of 3 pounds per minute. At the same time, liquid ethyl chloride, containing 0.1% of acetone, at a temperature of 32 C. was pumped under pressure into the reactor at the rate of 10 pounds per minute. The absolute pressure in the reactor was maintained at about 140 pounds pressure, which was suflicient to hold the temperature of the suspension in the reactor at 90 C. by refluxing of the ethyl chloride. The reactor was maintained about 92% full and the agitator speed was 45 rpm. The resulting suspension of alloy in ethyl chloride was worked through the reactor during a fifteen minute period. The reaction mass issued from the reactor continuously and was passed to the receiver for the recovery of the tetraethyl lead, sodium chloride, ethyl chloride and metallic lead. The operation was continued until about 700 lbs. of tetraethyl lead was made.

This process was repeated many times, varying the alloy feed rate over the range of 3 to 9 pounds per minute and the ethyl chloride rate over the range from 6 to 27 pounds per minute, while keeping the concentration of alloy in the initial suspension at from about 25% to about 33.3% by Weight. The rate of agitation was varied from 45 to 80 revolutions per minute. The outlet overflow was adjusted so that the reactor was operated either 92% or 68% full. Satisfactory operation was obtained under all these conditions. The yields were ordinarily between and calculated as pure tetraethyl lead and based on the weight of alloy fed. The yields, obtained in large scale batch operations in various plants,

. 9 are about 88.5%. The yields tended to be higher when the lower feed rates were used. The conversion of the alloy, determined by the amount of sodium hydroxide formed from unreacted alloy when water was added to the reaction product, was between 98% and 100%.

- A number of runs also were made successfully with slightly higher resulting yields and more rapid reaction at 100 C. and at 110 C. Operation at 80 C. was also mechanically successful but the yields were slightly lower in the above apparatus, using the same feed rates. Normal yields were obtained, however, when longer reaction times were allowed. Similar results were obtained in the absence of acetone or like accelerator, but maximum conversions and yields are most consistently obtained in shorter times in the presence of such an accelerator.

Example 2 Equal quantities of molten lead-sodium alloy, containing by weight of sodium, were put into three bombs, two of which had been previously filled with clean /2 inch steel ball bearings, and solidified. The bombs, con taining the ball bearings, were rotated for 16 hours in order to cause the ball bearings to grind the solidified alloy. It 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% tetraethyl lead. The unground alloy gave a yield of 86.5% tetraethyl lead.

. Example 2 has been included for purposes of comparison solely.

It will be understood that Example 1 has been given for illustrative purposes solely and that my 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 proportions and conditions of operation within the ranges broadly disclosed without departing from the spirit or scope of my invention. It will be particularly apparent that the apparatus, shown in the drawings and described, is only one of many forms that may be used. A similar reactor having a length of twelve times the diameter has been used successfully. Also sati'sfactory. agitation has been obtained by means of a series of flat paddles, attached to the central shaft and in the same plane with it, rotated by the shaft at from about 155 rpm. to about 210 rpm. The reaction chamber may contain baflles to ensure circulation and flow of the reacting suspension in the desired direction and to retain the reacting suspension in the reaction chamber for the desired period of time. The reaction zone may be formed by a plurality of separate connected tubular reactors arranged in series or incascade relation. Still other forms of apparatus will be apparent to those skilled in the art.

Thus, it will be apparent that my invention provides a novel process for making tetraethyl lead in a continuous manner which is a great advance over the processes which have been used or suggested prior to my invention. My process can be carried out more easily and far more economically that the prior processes. Also, my process employs cheaper and much less elaborate equipment than prior processes. Therefore, it will be apparent that my invention constitutes a very valuable and important improvement and advance in the art.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

. l. The continuous process for producing tetraethyl lead which comprises continuously .injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% 'by weight of sodium into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in" an elongated horizontal reaction zone maintained under reaction conditions and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.5 to about 4 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspendedalloy is reacting with the ethyl chloride and maintining it under reaction conditions until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

2. The continuous process for producing tetraethyl lead which comprises continuously injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal reaction zone maintained at a temperature of at least about C. and under a reflux pressure and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.5 to about 4 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the'resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at a temperature of at least about 80 C. and under a reflux pressure until the reaction is substantially complete, and continuously.

gated horizontal reaction zone maintained at a tempera ture of from about 80 C. to about C. and under a' pressure of from about 107 to about 255 pounds per square inch absolute and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.5 to about 4 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at a temperature of from about 80 C. to about 120 C. and under a pressure of from about 107 to about- 255 pounds per square inch absolute until the reaction is substantially complete, and continuously removing the ill resultant reaction mixture from the reaction zone through the discharge end thereof.

4. The continuous process for producing tetraethyl lead which comprises continuously injecting a stream of molten lead sodium alloy, containing from 9.9% to 10.1% by weight of sodium, into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal cylindrical reaction zone maintained at a temperature of at least about 80 C. and under a reflux pressure and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.8 to about 2.3 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation,

continuously flowing the agitated suspension lengthwise the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at p a temperature of at least about 80 C. and under a reflux pressure until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

5. The continuous process for producing tetraethyl lead which comprises continuously injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium, into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal cylindrical reaction zone maintained at a temperature of from about 100 C. to about 120 C. and under a reflux pressure of from about 170 to about 255 pounds per square inch absolute and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.5 to about 4 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injec tion of the molten alloy and of the liquid ethyl chloride While the suspended alloy is reacting with the ethyl chlo ride and maintaining it at a temperature of from about 100 C. to about 120 C. and under a reflux pressure of from about 170 to about 255 pounds per square inch absolute until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

6. The continuous process for producing tetraethyl lead which comprises continuously injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1% by weight of sodium into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal cylindrical reaction zone maintained at a temperature of from about 100 C. to about 120 C. and under a reflux pressure of from about 170 to about 255 pounds per square inch absolute and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.8 to about 2.3 parts by Weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a sus Cir pension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at a temperature of from about C. to about C. and under a reflux pressure of from about to about 255 pounds per square inch absolute until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

7. The continuous process for producing tetraethyl lead which comprises continuously injecting a stream of molten lead-sodium alloy, containing from 9.9% to 10.1 by weight of sodium, into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal cylindrical reaction zone maintained at a temperature of from about 100 C. to about 120 C. and under a reflux pressure of from about 170 to about 255 pounds per square inch absolute and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing about 1.8 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at a temperature of from about 100 C. to about 120 C. and under a reflux pressure of from about 170 to about 255 pounds per square inch absolute until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

8. The continuous process for producing tetraethyl lead which comprises continuously 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. into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal cylindrical reaction zone maintained at a temperature of at least about 80 C. and under a reflux pressure and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.5 to about 4 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at a temperature of at least about 80 C. and under a reflux pressure until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

9. The continuous process for producing tetraethyl lead which comprises continuously 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. into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal cylindrical reaction zone maintained at a temperature of from about 80 C. to about 120 C. and under a reflux pressure of from about 107 to about 255 pounds per square inch absolute and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, emplo ing from about 1.5 to about 4 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction Zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at a temperature of from about 80 C. to about 120 C. and under a reflux pressure of from about 107 to about 255 pounds per square inch absolute until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

10. The continuous process for producing tetraethyl lead which comprises continuously 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. into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal cylindrical reaction zone maintained at a temperature of at least about 80 C. and under a reflux pressure and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.8 to about 2.3 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the reaction zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at a temperature of at least about C. and under a reflux pressure until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

11. The continuous process for producing tetraethyl lead which comprises continuously 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. into a rapidly agitated body of a suspension of such alloy in liquid ethyl chloride in an elongated horizontal cylindrical reaction zone maintained at a temperature of from about C. to about C. and under a reflux pressure of from about to about 255 pounds per square inch absolute and simultaneously injecting continuously into said suspension a separate stream of liquid ethyl chloride at a temperature below the temperature of the reaction zone, employing from about 1.8 to about 2.3 parts by weight of ethyl chloride to each part of alloy, the molten alloy and the liquid ethyl chloride being injected into the suspension at points remote from the discharge end of the re action Zone, maintaining the resulting mixture in the form of a suspension throughout the reaction zone by subjecting it to mechanical agitation, continuously flowing the agitated suspension lengthwise of the reaction zone toward the discharge end thereof and beyond the points of injection of the molten alloy and of the liquid ethyl chloride while the suspended alloy is reacting with the ethyl chloride and maintaining it at a temperature of from about 100 C. to about 120 C. and under a reflux pressure of from about 170 to about 255 pounds per square inch absolute until the reaction is substantially complete, and continuously removing the resultant reaction mixture from the reaction zone through the discharge end thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,652,812 Calcott et al. Dec. 13, 1927 1,692,926 Calcott et a1. Nov. 27, 1928 1,974,167 Voorhees Sept. 18, 1934 2,091,114 Daudt et al. Aug. 24, 1937 2,574,759 Rodekohr et a1 Nov. 13, 1951 2,744,126 Mattison May 1, 1956

Claims (1)

1. THE CONTINUOUS PROCESS FOR PRODUCING TETRAETHYL LEAD WHICH COMPRISES CONTINUOUSLY INJECTING A STREAM OF MOLTEN LEAD-SODIIUM ALLOY, CONTAINING FROM 9.9% TO 10.1% BY WEIGHT OF SODIUM INTO A RAPIDLY AGITATED BODY OF A SUSPENSION OF SUCH ALLOY IN LIQUID ETHYL CHLORIDE IN AN ELONGATED HORIZONTAL REACTION ZONE MAINTAINED UNDER REACTION CONDITIONS AND SIMULTANEOUSLY INJECTING CONTINUOUSLY INTO SAID SUSPENSION A SEPARATE STREAM OF LIQUID ETHYL CHLORIDE AT A TEMPERATURE BELOW THE TEMPERATURE OF THE REACTION ZONE, EMPLOYING FROM ABOUT 1.5 TO ABOUT 4 PARTS BY WEIGHT OF ETHYL CHLORIDE TO EACH PART OF ALLOY, THE MOLTEN ALLOY AND THE LIQUID ETHYL CHLORIDE BEING ININJECTED INTO THE SUSPENSION AT POINTS REMOTE FROM DISCHARGE END OF THE REACTION ZONE, MAINTAINING THE RESULTING MIXTURE IN THE FORM OF A SUSPENSION THROUGHOUT THE REACTION ZONE BY SUBJECTING IT TO MECHANICAL AGITATION. CONTINUOUSLY FLOWING THE AGITATED SUSPENSION LENGTHWISE OF THE REACTION ZONE TOWARD THE DISCHARGE END THEREOF AND BEYOND POINTS OF INJECTION OF THE MOLTEN ALLOY AND OF THE LIQUID ETHYL CHLORIDE WHILE TH*E SUSPENDED ALLOY IS REACTING WITH THE ETHYL CHLORIDE AND MAINTINING IT UNDER REACTION CONDITIONS UNTIL THE REACTION IS SUBSTANTIALLY COMPLETE, AND CONTINUOUSLY REMOVING THE RESULTANT REACTION MIXTURE FROM THE REACTION ZONE THROUGH THE DISCHARGE END THEREOF.

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