Document 8V8nGZep4qYL1rNdepk4BRneB

oos Dr. K. A. Kehoe Mr. S. K. Locher Mr. J. V. Capinjola Stability of "Ethyl" Antiknook Compound New York Detroit November 21, 1947 enclosed are three copies of memorandum on "Stability of "Ethyl" Antiknock Compound", The report was written with the view of presenting infor mation relati*v9 to the stability of our product in a manner easily understood by safety engineers and other field representatives. The first draft of this report was reviewed b y Drs,. Calingaert and beatty and other members of the Chemical Laboratory,. Their additions and corrections were integrated in the final report. It is deemed desirable that this report should receive general distribution in the field since it contains information of interest to all who deal in the distribution of our product. The reader of this report should be cautioned in its use since it contains information of a restricted nature. This is ospeoially true for the information contained in the section dealing with the use of inhibitors for the stabilization of fluid,. Csp K G0C5339 ETHYL COHPORATIOH Research Laboratories Detroit, Michigan November 20, 194? Stability of "Ethyl" Antiknock Compound Stability of "Ethyl* fluid has bean traditionally considered as the problem of the Chemist, This is adit should be I&uover, a considerable amount of information has been collected on this subject which profitably should b in the hands of th field personnel It is not uncommon for our field people to b confronted with questions concerning the deposition of sludge in tanks, druao and in other facilities used for the storage of fluid The reasons for th presence of this sludge are probably not too wall understood, Hsnc it scans desirable that appropri- at information on fluid stability bo passed on to those who deal in the distribution of our product It is the purpose of this report, therefore, to present th results of recent laboratory investigations coaling with th factors of fluid stability, to discuss the use of inhibitors for th stabilisation of "Ethyl* fluid, and to interpret the laboratory data for field application General Considerations Description of Compounds Before proceeding to a consideration of the factors oa iluxa ata* bility, it may be well first to review the properties of the ohunioal compounds involved, spscially thou whicn oompriso sludge As you will recall, tetraethyllead is an organic molecule, that xs, the lead atom, ia attached to oarbon atoms The molsoula is composed of on atom of load attached to four thyl groups H h S} BD-C- represents an ethyl or as HH " . group For purposes of this report, molecular tetraethyllead is written as follows I ^ Bt-Pb<*Et t Eb . . When we apeak of organic lead salts, w m o a n v in general, the b u q ~ cessivo replacement of the thyl groups by other groups, such as chlorine or bromine Examples or organic lead sallis are triethyllead chloride^ diethyl**lead dibroaiido, etc. Th molecule is considered to b organic_in nature until all the thyl groups have been replaced b y other groups, at which time the^ molecule is said to be inorganic in nature Examples of inorganic compounds of lead are: load bromide (PbBra ), lead ohlorid (FoClg), lead sulfate (.PbS04 ). and lead oxide (PbO)0 GGG5D40 i 2c Slno organic lead salts are the more important compounds associated with fluid sludge, and yet least understood by the mon-chemist, a description of these compounds is given in detail. Trietfcyllead halides (EtsFbX) are colorless solids at room temperature. Triethyllead chloride decomposes when heated to about 120 C. (248 F.)o Tri- ethyllead bromide melts at 103 C. (217 F.), vd.th decomposition, to a turbid liquid Triethyllead halidos in the form of dust are exceedingly irritating to the nasal membranes when breathed; they cause excessive sneesing. If they are breathed for a prolonged period, they produce a severe headache* A very important property of trletl$rllead compounds is that they undergo a type of decomposition reaction to produce 'cstraethyllead. This takes place quite rapidly at elevated temperatures, for example during steam distillation, and also ocours slowly at room temperature This property of the compounds needs to be seriously considered whenever fluid sludge is handled in any manner. Information regarding the solubility of these compounds in different solvents is important. Vs'ith the exception of gasoline, triethylload halides aro very soluble in nearly all organic liquids, including tetraethylload, friethyl- lead bromide is soluble to the extent of QOfa by weight in ''Ethyl" Motor Mix? triethyllead chloride, to the extent of Sfj by weight in "Ethyl" Motor Mix Hanes, it is to b e noted that fluid decomposition products, such as the triethyllead halides, will tend to dissolve in the fluid and not appear as deposited sludge. Triethyllead hydroxide (EtsPbOH) is insoluble in "Ethyl" brand of anti knock compound and gasoline, but fairly soluble in water. , ' / The other organic lead (diallcyllead salts) and inorganic lead salts are practically insoluble in antiknock fluid. As a result, when they are formed as deterioration products of the fluid, they will immediately come out of solution, and deposit on the bottom or sides of tho container These salts when pure are colorless, but their deterioration on standing in the presence of traoes of air or water yields yellow and brown oxides of lead, ao that most of the. sludges observed are colored Composition of "Fluid" Sludge Generally speaking, the term "sludge" designates decomposition products whioh settle to the bottom or sides of the container. The term "sludge" as used in tho Laboratories of this Corporation, however, means decomposition products which ar soluble in the fluid or potential sludge as well as the decomposition products 'which precipitate. In substance then, by the term "sludge" as used in this report ia meant both potential sludge and precipitated sludge. Although the exact composition of fluid sludge will depend on various conditions (such as composition of fluid, temperature, exposure to air, etc.)* in general, precipitated sludge ia composed of inorganic lead compounds, such as lead bromide, lead chloride, "lead oxides, bismuth oxides; and organic lead \ compounds, suoh as diethylload dichlorido and dibromide, and various oxides of these compounds 00C5341 K <>Je Elementary analysis of typical precipitated sludge3 obtained from commercial fluid (recent) in the laboratory is givens ' Analysis of Precipitated Sludge ?vXsa&' /Tls'roialne 'Jg^lD~oHSQ~ Motor Mix Aviation Mix 58.6 59.8 7.72 7.96 0.0 To present a further picture of the composition of precipitated sludge, the following table gives analysis of sludge removed from a refinery weigh tank for "Ethyl" Antiknock Compoundj ` Compound Analysis of Weigh Tank Sludge * b y weight Organic load salts Inorganic lead salts Bismuth compounds Ferric hydroxide 27 19 59 15 It is to b o noted that this sample of sludge m s obtained from a tank which had been in operation from. 1951 to 1944 and hence had a high bismuth content for the reason explained below. The ferric hydroxide content* of course,,, ia rust from the tank. The potential sludge of "Ethyl" fluid is composed mainly of triethyllead bromide and triethylload chloride. In due time these compounds become oxidised by the atmosphere and precipitate as sludge. In small amount3 dissolved sludge is considered to have no deleterious effect on the storage of fluid. However, a fluid containing a relatively largo amount of potential sludge is not desirable sine when it is dissolved in gasoline the triethyllead salts will precipitat due to their limited solubility in that medium. . The disadvantages of precipitated sludge are obvious. The sludge may build up in drums* weigh tanks, linos* tc. and consequently increase the handling and distribution problems of the fluid. .- Storage Stability of "Ethyl" Fluid Stability of Fluid Prior to 1940 Prior to about June, 1940 it was generally noted that a considerable amount of sludge had deposited from "Ethyl" antiknock fluid into drums and tank car3. This condition was a source of considerable annoyance to the Corporation end to it8 customers. Research work in our Chemical Laboratory and subsequent development by the Ethyl and duPont manufacturing groups provided a moans of eliminating the ready sludge-forming materials from tetraethyllead before it was blended to "Ethyl" fluid. This came about in the following way. HZ' 00C5342 J S; 4, At the time analysis of sludge obtained from the fluid invariably showed high bismuth content. Consequently, it was thought that tha bismuth compounds in the tetraethyllead were largely responsible for the excessive sludge formation. Laboratory investigations revealed that this was true. It was found that commercial load which was being used in the manu facture of tetraethyllead contained a small percentage of metallic bismuth. In the reaction for the formation of TEL, the bismuth in the alloy would also reaot and form a compound t riethylbismuth. similar to TEL. This compound in the laboratory m s noted to bo highly unstable and easily, oxidised by air to form compounds which would dopoait from the fluid. Laboratory studios showed that TEL could be freed of this compound merely b y blowing air through TEL before it was blended into fluid. This ' procedure was incorporated by the Manufacturing Department. As a result, the aludgo at that time in crude TEL was groatly reduced, from 0.2-0.3 g, of precipitated sludgo/lOO co. TEL to 0.01 g. sludge/100 co. TEL, and m s later reduced still further, to 0.002 go/l00 cc. TEL. This has resulted in the elimination, for all practical purposess of the difficulties with sludge settling out in relatively large amounts in blender, bulk storage tanks, drums and tank oars under normal storage conditions. Stability of Current Fluid and the Factors Affecting its Stability As a result of the increased purity of TEL, tha sludge problem of "Ethyl" antiknock fluid m s greatly diminished. Current commercial fluid contains only a trace of deposited sludge. On blending the fluid or shortly thereafter, a trace of potential aludgo is formed b y reaction of th TEL with the ethylene dibromide or impurities therein, but this amounts to loss than G.3;;S of the TEL content, and under proper storage conditions the reaction con-os to a halt. Although our manufactured product, as delivered to the customer, is almost entirely without sludge, under certain conditions of storage "Ethyl" fluid will "ago" with consequent formation of a slight amount of sludge. The faotors which affect the storage stability of "Ethyl" antiknock fluid ars discussed In the following sections. 1. Effect of Oxygon or Air. - Laboratory studies and field experience show that w h e n ^ fltHH"To exposed to air deterioration of the fluid occurs. The air is dissolved b y the fluid, slowly on standing and rapidly when th fluid is agitated. At room temperature "Ethyl" fluid can dissolve 10/6 of air b y volume). The sludging reactions of fluid in th presence of air occur* in two stagest first, & fast oxidation reaction producing a soluble load sludge, presumably an alkyllead oxide; second, by a reaction between this compound and ethylene dibromide (a constitutent of fluid) to form triethyllead bromide. The latter compound constitutes potential aludgo, if. the amount of available air ia limited. If the amount of air ia unlimited, the potential sludge is converted to decomposition products which are insoluble in the fluid and settle to the bottom of the container. In this connection, laboratory studies have shown that there will b several times as much potential sludge as precipitated sludge. " 0005343 5 In a typical experiment "Ethylu totor Mix on standing at room temper ature over a period of seven days in a sealed quart jar with a large but limited air space gave 0.16# (weight % TEL) as prooipitatad sludge. In similar experiments and under the same conditions it was found that fluid in open quart jara gave about 50 times as m uch precipitated sludge as fluid in sealed jars. With all other variables constants therefore, in general* it can b stated that the extent of fluid decomposition will depend on the amount of air available. 2. Effect of Time and Temperature. - In order to determine the effects of time and temperature on fluid stability, laboratory tests wore run in quart bottles for periods up to 28 days and temperatures ranging from 50 to 96" F. In the tests where an unlimited amount of air was available, it was found that sludge formation (precipitated sludge) increases with increasing time and temperature. In these tests it was also concluded that where air is not avail able the increased temperature merely served to accelerate the rate of approach to a constant sludge level. The effect of time and temperature on fluid stability have been demonstrated in drum storage tests also. In on tost, a drum of fluid (Motor Mix) was stored for 96 days at a constant temperature of 140 F. Inspection and analysis of the fluid after the tost showed that the decomposition of the fluid to soluble sludge increased slowly to tb extent of 0.3# of tho TEL, and that there was very little precipitated sludgo, la tills tost, incidentally, the pressure of ths drum rose initially to a maximum of 19 pounds gagaj within ons day the air in the drum (3#) dissolved in the fluid, tho drum became shell full, and tho pressure fell to 8 pounds where it remained constant for ths duration of ths tost. In summary, tb. factors of time arid t snipnature (up to 60 C. (i40 ?.,,)) contribute very little to sludging of fluid, if the fluid is in closed containers and consequently exposed to only a very small amount of air. Conversely, they contribute) greatly to fluid sludging if the fluid is being exposed to an unlimited source of air. 3, Effect of Light: The exposure of fluid to light in any form inoreaseo 3ludge formation. In a representative series of laboratory experiments, 234 ml,-samples of fluid, protected by a water layer, were stored in pint bottles and exposed to daylight and darkness for a period up to 20 months. At the end of this storage period, the fluid sample contained a l/8*inoh layer of sediment (pre cipitated sludge), yellow crystals of material formed on the sides of tho bottle, and there was a brownish frosting of the glass above the fluid. Ths samples exposed to daylight gave 0.9 gram of precipitated sludge, while the samples stored in the dark gave 0.3 gram of precipitated sludge. Thus, in this case at least, daylight exposure of the fluid gave a three-fold increase in sludge formation over the samples stored in the dark. At the present time "Ebhyl" antiknock fluid is being handled and distributed in opaque containers; and as a result, there is very little ohanoo for exposure of the fluid to light. There is, however, some light exposure of aaall quantities of fluid U3ed in gasoline laboratories for testing purposes. /<' 0005944 6* Protection of "Ethyl0 Fluid Against Deterioration by use of Inhibitors Although "Ethyl" Fluid is relatively stable under ordinary storage conditions with only trace formation of sludge, the Corporation has and is giving much consideration to the problem of finding a suitable inhibitor for "Ethyl" antiknock fluid, A completely stabilised fluid is considered advau*. tageous both from the economic and safety standpoint, Such a fluid would eliminate all distribution problems from the standpoint of sludging in the containers, and would minimise the handling of lead sludges in cleaning gasoline storage tanks and fluid bulk storage tanks. Of the many inhibitors which have been tostod in the laboratory for the stabilisation of fluid. Shell 2&HSB (?.jt4'd:lmathylS-tertiary butyl phenol) has proved to be on of the most effective. Laboratory investigations have demonstrated conclusively that inhibitor 24MSB at a concentration of 0,1/5 (based on weight of TEL) in "Ethyl" fluid considerably decreases the amount of sludge formed when the fluid is exposed to air, The use of the inhibitor in this concentration gave satisfactory protection of "Ethyl" antilcnook fluid for three weeks at 40 G, and for one week at 50 C. The reason the inhibitor does net give unlimited protaction is that the inhibitor itself is used up in. time, Shell 24M53 inhibitor has been put on the list of satisfactory inhibitors for use in the stabilisation of "Ethyl" antiknock compound. How- rer. at presen't*- it is being used in special oases only. Regarding its uua in commercial fluid, a careful study of the subject made by the Corporation showed that there was no need for a stabiliser under our normal bulk handling of the fluid. In addition, it was felt'that since the inhibitor cannot elimi nate sludging completely, its use cannot bo justified. The inhibitor is currently being used to stabilise fluid shipped in ore-liter-cans, The us of canned fluid, you will recall, involves the use of fluid in the 'laboratory under conditions whore it is highly exposed to air. Opened end partially used cans of fluid arc subject to long periods of storage with Intermittent exposure to air upon opening the can to remove a small portion of the fluid, Without inhibitor this exposure resulted in fluid burettes becoming coated with a deposit difficult to clean8 and the fluid itself became ha?.y, - In order to eliminate or minimize' these sludging reactions Ethyl Corporation is supplying "Ethyl" antiknock fluid (Aviation) in a dilute form (solvent is 7Cf/<>xylene + ZO/o n-hsptane b y volume) and stabilized with 0,155 24M6B, as a service to our customers. Laboratory tests have shown that the inhibited canned fluid is satisfactorily stable for use during periods up to six months. Application of Fluid Stab i l ity Data to Field Uso In order to supply our customer companies fluid with tho least amount c? deterioration,, consideration of tho follovdng precautions in the field ia suggested: . 0005345 7 Weigh Task Storage Our present system of storing fluid in customer refineries in weigh tanks is advantageous sinoe it does not allow exposure of the fluid to light at any time. Glycerine is added to fluid in weigh tanks for the purpose of forming a protective blanket. The glyceri ne, being insoluble in the fluid and having a density lower than the fluid, will fora a separate layer on top of the fluid. 3y means of this layer (blanket) contact of the bulk fluid with air is largely guarded against and the tendency of the fluid vapors to escape is greatly decreased. It cannot be emphasised too strongly, therefore, that all weigh tanks should contain a glycerine blanket, if space in the tank is available for it. Without a blanket, deterioration of the fluid can be expected to increase, specially if the vent line has to be left open. In the operation of a mixing plant, there exists tbs possibility of pulling air through the fluid, which should not be permitted. This may happen when the supply of fluid in the tank is lov;, at which time air is sucked tnrough the standpipe filling the tank with air. This, of course, should be guarded against since a fresh supply of air means a condition for further deterioration of the fluid. In dealings with customers it is good practice to urg a reasonable turnover of the fluid in the tank. This is n wise directive since it is known that tho longer the storage time the greater the chances for. Increased sludging of the fluid. . Consideration should also be given to the temperature of the room whsre fluid is stored. Excessive fluid storage temperature, of course, tends to accelerate decomposition reactions. Direct sunlight should not b allowed to strike the tank. . These precautions are ordinary considerations for plant operations, they are repeated hero for emphasis only. . Urua 'borage '" ` - la the storage of fluid in drums in the field there are two primary considerations from the standpoint of temperature and light. The temperature under which fluid i3 stored should never exceed SO C. (122F.) for any period of time* In addition, the fluid should be so stored that it is proteoted from direot sunlight at all times. This, of course, is accomplished b y suitable roofing which ordinarily i3 available except in extrema oases. A word of explanation is in order at this point, regarding the tern "sun temperature1': It has been established that if a drum of fluid is exposed to the sun in a high temperature area (120 F.), the maximum temperature of the fluid will be as much as 22* F. above the prevailing maximum air temperatures. Hence, the reason for the recommendation for storing fluid drums in the shade, especially in hot climates. K 0005346 In the storage of drums care should b exercised so that the drum does not breaths air unnecessarily. This is usually accomplished by not permitting bungs to become loosened* As to blowing air through fluid* this should not bo permitted in mixing operations. The recommendation is the same as discussed pre'tn^aly for 'weigh tank storags* Fluid is not shipped in old rusted drums. It has boon demonstrated in tho laboratory that rust may catalyse and accelerate decomposition reactions However, if such a drum comes to your attention it should be marked so that the Shipping Department will be aware of its condition when it is received In conclusion* if a case of excessive sludgi&g is noted in the field, it should be reported at once to those- concerned. Investigation of the condi tions under which the fluid was stored end laboratory analysis of the fluid will provide data for further interpretation of fluid sludging* 8$* C:p John V. Capiajola 0005347