INDUSTRIAL AND ENGINEERING CHEMISTRY
2616
LITERATURE CITED
(1) Ameye, M . , Bull. acad. rog. B e l g . , 31, 227 (1899); Chem. Zentr., 1899, 11, 96. ( 2 ) Beilatein, "Handbuch der. oiganischen Chemie," S'ol. .I.4th ed.. p. 395, New York, G. E. Stechert 8r Co., 1922. (3) Bell, E. R., Dickey, F. H., Rnley, J. H., ItusL,F. F., and Vaughan, W.E., ISD.ENG.CHEX.,41, 2597 (1949). (4) Bell, E. R., Irish, G. E . , Ralep, J. H., Rust,, F. F . , and T.aughm, W. E., I b i d . , p. 2639. (5) Delacre, M., Bull. ucad. my. Belg., 32, 446 (1900); C h e n ~Z. e n t r . , 1900, 11, 255. (6) Errera, G., G a , z ~&in. . ita!., 14, 504 (1911).
C
Vol. 41, No. 11
(7) Hoch, H., and Lang, S., B e r . , 77B,257 (1944). (8) McGreal, M . E., Niederl, V., arid Xiederl, J. B., J . Am. C'hem.
SOC., 61, 345 (1939). (9) Merck's Index, 5th ed.. p. 703. Rahway, N. J., Merck & r o . , Inc., 1940. (10) Milas, N. A,, and Surgenor, D. &I., J . Am, Chem. Soc., 68, 205 (1946). (11) Nawrocki, P. J., Kaley, ,J. H.. Rust, F. F., and S'aughan. Tf7. E., I K D . E N G . CHEM., 41,2604 (1949). (12) Rust, F. F.,and Vaughan, W . E . , Z b i d . , g . 25Q5. RECEIVED August 17, 1948. Presented in part at the meeting of the Gordon Research Conferences of the American aciation for t h e Advancemrnt of Science, Colhy Junior Collwe, New Londom, N . H., June 19-18,
SION-INHIBITED FUELS JOSEF M. MICHEL AND KARL F. HAGER Ordnance Research und Development Division, Fort Bliss, Tex.
A survey is presented on already-known niethods and recent advances in the field of corrosion prevention in pipe lines, storage containers. tanks, and other equipment in contact with fuels, even under severe conditions-e.g., in the presence of bea water. Of the three possibilitiesproper choice of corrosion-resistant construction materials, surface protection of metals or all03 s in question by suitable treatment, and admixtures to the fuel in order to produce surface passivity-only the third method promises an extended technical application and sufficient endurance in practical use. Research in this field starting in the middle of the 1930's is reported, particularly with regard to prevention by use of fluoride cartridges of
dangerous corrosion b3 fuel containing tetraethj Head of light metal (magnesium) tanks in airplanes. Further development stimulated b y extenshe investigations on emulsifying agents led to the surprising result that, without regard to the construction materials used, eien a small addition of Rlepasin-sulfamido-acetic acid-sodium sal t to the fuel prevents anj corrosion (Mepasin refers to a certain fraction of hjdrocarbons gained by the Fischer'rropsch s>nthesis, chain length from about 12 to 18 carbon atoms). These results present a prospect of sol\ing many corrosion prohlems, starting at the oil well and ending with the last fuel consumer, by the simple addition of the smallest amount of such chemicals.
T
protection, decreasing after a certain time, was not suitahle 1'01. all construction materials. Finally, often the properties of the blended fuels did not meet the conditions required for mot,ors. Also lacquering (ZS)!electrolytic deposition and oxidation, metallizat'ion, ceramic (58)and plastic coatings ( 2 1 ) ,etc., were too expensive or not useful when in operation for any great period of time (9, 12). I n many cases ivhere construction was complex the usual methods gave less valuahle protection than under m i . mal conditions. I n spite of partial success, it was recognized that a general solution of the problem could he reached only by treatment of the fuels, for by this means all parts of the const'ruriion could he protected. The situation became urgent in 1936 when very serious corr'usion phenomeria were ohserved in magnesium alloy fuel tanks in airplanes serving the route from Rotterdam to Batavia. The t,anks had been in servire only a short, time. Since a change of tank construction mat'erials-connected with an unwelcome increase of weight-was undesirable, the best method was t,o t r y the second method mentioned above and search for "additions to the corroding medium to produce passivity'' (3, 24, 1.5, 18-20, 22, 33, 47, 52). After expeyimentat,ion in the laboratory, special chemicals \vera put, in fuel tanks. These agents contained mainly alkali fluorides and additional salts-e.g., magnesium carbonate-for buffering and maintaining a certain concentration range of hydrogen ioiiii with pH above 7 (18-$0,2a, 33). In this way, the problem could he solved relatively quickly. Important in the elaboration of this method is the fact t,hat, serious corrosion phenomena wew observed only in the presence of water which was not' dissolved in t,he fuel, but appeared as a second phase on the bottom of the tank. This water may have entered the tank either by injection wit,h the fuel, by careless workmanship, or by precipitation from the air inside the tank in cooling. This corrosion is extremely serious in the presence of fuel containing tetraethyllead, for this
HE phenomena of corrosion involve not only problems of applied chemistry and engineering hut also interesting problems for basic research in different branches of science. The loss of material ma?- be only a small percentage of the whole construction, but necessitates replacement of the entire equipment, when corrosion exceeds a certain point,. Therefore, protection increases in importance the higher the ratio of cost of replacement t o the loss of material hy corrosion. Corrosion may be prevent,ed by the choice of proper materials, such as special metals and alloys. In addition, two other principal ways exist. They are the protection of the surface of the construction material by proper treat,ment (the treatment varies according to t,he requirements of operation), and additions to the corroding medium to produce passivity. I n producing passivity, there is the special task of diminishing the aggrespiveness of fuels ( 5 , 6 , 9, 12, 13, 24, 29$8, $7, 40,43, 49). The use of fuels containing suitable inhibitors increases the security of st,ora,geand transportation as well as the safety of operation. For the following data, fuels such as alcohols and their mistures with wat,er are not considered, because addit,ions for these fuels such as Akorol and pH-buffered alkali chromate, chlorate, and perchlorat,e mixtures have been kno\w for several years (29, 31, $ 2 ) . However, this report n-ill deal with experiments concerning additions to fuels such as hydrocarbons, especially gasoline. The problem of corrosion has been wdl known for a long time in the distribution of crude oil in pipe lines and pump stations. Many physiOa1 and chemical proposals were made in publications and pat,ents-e.g., proper metals and alloys ( 2 , 12, 13, $6, S6), dehydrating and desiccating (2J9, 18, 17, 43, 61), sodium silicat,e (49,4 6 ) , sodium sulfite (43), sodium nitrite, proper p H value of the solution ( 1 1 , 45, 49, 63, 54), aliphatic and aromatic amino compounds ( 1 4,7 , 8,b3, 3.9, 41,&9, bO)--hut, no sat,isfactory s o h tion was found. Eit,her the procedure did not meet the requirements of prizen-orthy a,md technically simple solution, or the
INDUSTRIAL A N D ENGINEERING CHEMISTRY
November 1949
I’
--.-.
I
CONTAINER
THE CONTAINER
CORROSION FfTTlNG
.
A
‘-GASKET
DE T AIL AT ”A”
2617
above, only such additions could be useful which are soluble in water and fuel (independent of its special composition). Protection is needed in every phase, particularly on the inner surface of the tank near the interface between fuel and water. After tests using numerous compounds such as aliphatic and/or aromatic amines with 8 carbon atoms a t least (2s)--naphthylamine, phenylhydrazine (41), soybean lecithin (8, 39, @), N-octylhydroxyethyl-p-amidophenol (7), alkylamine salt of alkylpyrophosphoric acid ester (60), mercaptobenzothiazol ( 4 S ) , ester of a phosphoric acid (48), naphthenic acids (167, benzvlaminophenol (S9), amino alcohols and/or amino esters (10), hydrocarbonamine-chromates or hydrocarbon-amine-fluorides (55), special waxes and resins-it was found that sodium salts of hydrocarbonsulfamidocarboxylic acid-e.g. acetic acid (&)-fulfill all specifications required. The main field, however, of application of a mixture of these compounds with high chain length hydrocarbons (12 to 18 carbon atoms), particularly their emulsions with water, has been confined as yet to the preparation of emulsifying lubricants for light and heavy metal machinery, especially iron (cutting, turning, drilling, threading, broaching, deep-dr illing, deep-drawing) . DESCRIPTION OF PREPARATION AND CLEANING OF SPECIMENS
SMALL BAG WITH lNHl8lTOR
Figure 1.
Corrosion Fitting Set in Fuel Tank
compound decomposes in the interface between fuel and water, forming lead oxides which, as parts of local elements, promote corrosion rapidly. For instance, containers made from magnesium alloys (98.5% magnesium, 1.5% manganese or 92.3% magnesium, 6.5% aluminum, 1.0% zinc, 0.2% manganese) were perforated more often a t the interface between gasoline and water or in the water phase itself, sometimes-according to the test conditions-within a few days. On the other hand tanks provided with cartridges containing buffered fluorides-e.g., mixtures of ammonium fluoride, sodium fluoride, and magnesium carbonate-showed no corrosion even after months of testing. The efficiency of those mixtures depends on two facts: a constant surface passivity of the magnesium alloys by formation of a protective layer produced by the aqueous fluoride solution; and a stabilizing effect of these salts or their solutions on the tetraethyllead itself, for it was proved by a test series that the decomposition of the tetraethyllead-highly catalyzed by light and moisture-was greatly retarded by neutral fluorides ( 1 9 ) . For the practical use of this procedure, such as in airplane tanks, a corrosion fitting was developed. A little bag containing the inhibitor was sealed in a perforated cartridge by screw cover. The fitting had to be placed a t the deepest part of the fuel tank because there the sump originates (Figure 1). The fluoride cartridge provided for the fitting weighed approximately 35 grams and proved sufficient for 1000 flying hours. The surprising effect of such additions may be best seen from Figures 2, 3, and 4. Other investigators have carried out similar tests using alkali dichromates and/or chromates. The results were considered good but reliable only when suitably neutral or alkaline buffered mixtures were used (S, 14, 18, SO, 47). These phenomena occurring during the lapse of corrosion were important for all further investigations in pursuit of chemical compounds that, if added in small amounts to a fuel, would make it corrosion proof. According to the conditions described
For the preparation and cleaning of corrofiion specimens, an over-all outline is given by B. B. Knapp in “Corrosion Handbook” ($6). In the authors’ case, the following methods were used : Preparation. IRON.The gallon containers, used for the pilot test series, were supplied machined and so it was suitable t o finish all the specimens by simply resurfacing them with No. 4/0 abrasive paper only, except the edges that were machined in order to remove the sheared metal, After this treatment degreasing was carried out in a boiling solution containing 15 grams of sodium carbonate, 30 grams of sodium hydroxide, and 1.5 grams of soap per gallon of water. Then the specimens were rinsed, first with water, finally by immersion in a 70% methyl
Figure 2. Corrosion by Leaded Gasoline of Metal Strips Connected with Aluminum Rivets 1. Mg-AI 2. Mg-Fe 3. Mg-A1 4. ME-Fe
With sump but without addition of fluorides With sump and addition of fluorides
2618
INDUSTRIAL AND ENGINEERING CHEMISTRY
alcohol solution (50" to 60" C.; pH, 7 to 8) and immediately dried. For identification purposes partitions in contact with the different strata were previously marked. MAGKESIUM AND R I A G m s I u h i ALLOYS. When containers, pipe lines, or other equipment made from magnesium or its alloys were used, strict attention was paid so that all these parts are delivered with the proper surface treatment. Otherwise, they will be corroded during shipment, especially if no suitable after-treatment was applied on welded pieces.
Vol. 41, No. 11
MAGNESIUN AXD MAGKE~ICX ALLOYS. After some experiments with uncorroded specimens proved t,hat solutions of chemically pure chromic acid will not produce any losses on base metal, the following method was used for the removal of corrosion products: 15% chromium trioxide, c.P.; 10-minute t,reatmciit a t 50 O to 60' C. As soon as further losses in weight are no longer observed, the samples are rinsed in a 50% methyl alcohol-witer solution (cont,aining about 0.1% chromate; pII, 8 t o 10) and dried. Another procedure using 10 to 2OyGhydrofluoric acid, which does not cause any losses on bitse metal, was found unsuitable for the removal of the corrosion products. The reason mag be t,hat insoluble magnesium fluoride is part,ially formed which can be removed kij, mechanical means only. Even after this treatment the speciinens do not look satisfactory; therefore, the method was abandoned. A few comparative tests xpplyirig samples wet scrubbed Kith pumice were performed in order t o find out t,he efficiency of the protection provided by the chromate treatment. The only decisive difference found is the &lag in time before corrosion starts. The now S o . 10 treat,ment, of course, retards it,, but bocomes ineffective whcin the process has completely developed.
Figure 3. Corrosion of 3fagiiesium Containers by Leaded Gasoline Bottom of fuel tank with fitting but without fluoride cartridge; sump without addition; testing period, 6 weeks
A11 the gallon cont,ainers to he tested with fuels were subrnit,ted to the Dow hie. 10 treatment consisting of pickling in a nitric acid-dichromate bath and hoiling the chrome-piclrled parts in a 10 to 15y0solution of dichromat,e for about 30 minutes. After this treatment the test samples were handled in the same way as the iron samples, being rinsed in a 50% methyl alcohol-water mixture (50" C.; pH, 7 to 9) and immediately dried. ALuRmqixr. The containers, like those made from iron, were suppliedm~,rhiied. According to this, a we ice seemed suffi:tieritl, followed hy rinsing \I' a 50% methyl alcwhol-water mixture (50' to 60" C.; 0.0S% pota,ssium chromate; pH, 7 to 9) and inimedi Cleaning. I R , ) s . Corrosion was measured by determining tlie rveight loss. Therefore, specimens must' be thoroughly clcanod of all corrosion products a t the end of the test. There are two different methods that proved satisfactor?. after preliminary tests showed that no base metal would he removed by these treatments: 9. Boiling in a 10% sodium hydroxide solution containing 0.05 to 0.1% potassium chromate B. Cathodic treatment in 10% sodium hydroxide solut'ion at temperatlures hetween 40" and 50" C;
First the corrosion products (ferric and ferrous hydroxides, mostly) are loosened by a 5- to 10-minute treatment. JVhile much of the rust is taken off by this t,reatment, the remainder which adheres more firmly t,o the surface is removed hy scrubbing the specimens with a. bristle brush. Finally, the samples are treated in a boiling 50% methyl alcohol-rvat,er mixture up t o t'he point where no allialine reaction is found (indicator, phenolphthalein). This procedure may be repeated till no further loss in weight is observed. The following table shows two typical results: Bheet Metal, SAE 1010 Treatment 1 Treatment 2 Treatment 3 Treatment 4 Cnoorroded saiiiple
Weight _ _ _ _ - LoRzeb i n hIg /Sa. Dm. Pioceduie A Procedure B 113
131 140 140
0.7
189 202 208 206 1.2
Figure 4. Corrosion of Magnesium Containers b) Leaded Gasoline Bottom of fuel tank with fitting containing fluoride cartridge; sump with addition of neutral alkali fluorides; testing period, 8 months
ALuhm-uhc. In this case ab well a 1551, solution of chemically pure chromic acid (50" to 60" C.; 10 minutes) can be used foi the cleaning of specimens as no losses on base metal were observed on tests 11 ith uncorroded specimens. In addition to this, it is very convenient to have the same procedure for all light metals and their alloys. The following table gives two typical examples, one for Dow Metal 31, the othcr tor 28 .4lcoa:
Treatment, 15% CrOa, 50-60'
Step 1
C.
Step 2 Step 3 Uncorroded saniple
. _ SVeiXht _ _ _Losves _ in ~ Mg./Sq. Drn. Dox,AI-sheet metal Type 2 3 Alcoa-sheet metal (98.57c LIg, l..i"/C>In) (99% All
~~~
87.4 92,6 92.7 1.8
36.3
40.2 40.2 0.6
TESTS
Preliminary tests ruiining for about 11 months in this country have been carried out in the Collowirig manner:
A t ambient temperature ordinary iron strips, 1 1 / 2 X 5 X 1/32 inch were placed in 4 closed glass containers half filled with gasoline, Type R 72 octane, Standard Oil Company of Texas. To acceleratc results, about 2% of water was added to each container, ordinary drinking wvatcr t o one, sea water or a 3% sodium chloride solution t o the other. Tests were made with addition of
November 1949
Figure 5. 1. Tap water 2. Sea water 3. Tap water 4. Sea water
INDUSTRIAL AND ENGINEERING CHEMISTRY
Iron Sheets i n Gasoline W i t h 0.05% i n h i b i t o r Without inhibitor
0.05% inhibitor to the fuel. The results of these tests after 4 months are shown in Figure 5 . The corrosive action of the fuel without the addition of an inhibitor can be divided into three zones: water phase of the liquid; liquid fuel phase; and vapor phase above the liquid. Figure 5 shows that tanks constructed from iron become unsuitable under the conditions applied. The pictures also show the verv marked effect of the addition of a trace of inhibitor. Considering these very promising results, new tests were initiated with special gallon containers of varying construction materials. First, iron containers, cylindrically shaped with welded seams, half-round bottoms and sealed with screw closures and leather gaskets (Figure 6) were filled with about 0.5 gallon of fuel. Each tank contained 2000 ml. gasoline (type as mentioned above) and 40 ml. water, city supply. One received an additional admixture of 1 gram of inhibitor. After 3 months’ treatment at ambient temperature (containers not having been shaken), the container without the inhibitor was heavily corroded on the bottom (water phase) and remarkably corroded on the sidewalls (gasoline phase). The results of these tests after 10 months are shown photographically in Figure 7. Figure 7, right, is of the inside of the tank containing no inhibitor, while Figure 7 , left, is of the tank with inhibitor. Corrosion is not limited to the bottom of the container (water stratum); the wall in the gasoline and even in the vapor phase shows serious attack. Moreover the photographs are significant in that they show markedly the result of this inhibitor. The container with the 0.05% addition of inhibitor remained essentially unchanged during this experiment; transportatherefore, it seems that for the purpose of s el corrosion tion an addition of only 0.05% inhibitor m proof for every practical use. The excellent condition of the containers did not change even when they were kept moving on a plate feeder.
While iron will usually be the construction material for large fuel tanks for storage and distribution systems such as pipe lines, pump stations, etc., light metals may be used for fuel containers, fittings, valves, pipe lines, pumps, etc., especially in aviation. Therefore gallon containers of aluminum and magnesium alloys were also tested under the same conditions. Material used in these magnesium containers is Dow M consisting of 98.5$4 magnesium and l.5Y0 manganese. Welding used was standard Heliarc with a direct current and tungsten tip; welding rod was commercial Dow M with a melting point a t 1200O F.; no flux was used. After completion of tanks they were submitted to a Dow No. 10 treatment, both inside and outside without other protection (discussed above). After 2 weeks, serious corrosion on the magnesium tank had occurred, and 40 days later the bottom of the container was partially perforated as no protecting agent was added t o the fuel. The condition of the tanks is shown in Figure 8; Figure 8, right, shows the inside without inhibitor after 8 weeks. Because of the heavy corrosion taking place in this period, no structure could be seen a t all, only a surface overcrowded with decomposition products (magnesium hydroxide and magnesium hydroxide with mag-
2619
nesium chloride). However, these corrosion products were carefully removed with 1% nitric acid, and small holes were revealed around the bottom (interface gasoline-water) of the tank (Figure 9). On the other hand Figure 8, left, shows that the tank which contained corrosion-proof fuel had not the slightest symptom of corrosion a t the end of 8 months’ exposure. Results such as these far surpass the best results of surface treatment including an adt of lacquer. me favorable results were found when these corrosionwere used with aluminum tanks. These tanks were manufactured from the usual commercial metal [99yo aluminum, remainder mostly iron, silicon, copper (type 2S)] using oxyacetylene welding and a coated aluminum welding rod (Aladdin type). The condition of the containers after 11 months’ exposure with normal and protected gasoline may be compared in Figure 10. The difference is distinctly visible. Quantitative data on the progress of corrosion are given in Table I and Figure 11. Figures 7 to 10 clearly demonstrate that iron corrosion is uniform and homogeneously progressive while magnesium corrosion irregularly appears in the form of points and dots. The latter is far more dangerous because it is uncontrollable and, therefore, entirely unpredictable.
Figure 6.
Gallon Container C u t in Half
DISCUSSION OF RESULTS
The results were striking in that only 0.05 and 0.1% inhibitor were added. They are explained by the following facts: The compound (Mepasin-sulfamido-sodium acetate) used has a very high affinity t o the metal; therefore, it forms films bonded firmly on the surface. From this fact it is observed that the field of development of metal-active compounds has just opened t o further progress. It is a t this stage comparable t o the moment when research on dyestuffs had to fix the constitutional conditions by which a molecule becomes fiber-affinitive. The Mepasin-sulfamidoacetic acid is polar, the metal-active carboxyl groups being situated on the end of the carbon chain. Moreover, the bridge between the hydrophobic and hydrophilic groups has a peculiar quality, showing bonded to the nitrogen a hydrogen atom that is movable due to the influence of the acti-
INDUSTRIAL AND ENGINEERING CHEMISTRY
2620
Figure 7.
Iron Containers after 10-Month Test Period
Right. Without inhibitor L e f t . With inhibitor, 0.05 % Mepasin-sulfamido-sodium acetate
vating sulfur dioxide group. Thus it can cause, via the hydrogen chain linkage, the lateral netting of the molecule chains in the same fashion as the fibrillary ligature of the silk-fibroin albumen molecule (25,28,40,44).
Figure 8.
Vol. 41, No. 11
Magnesium (Dow Metal 31) Containers
Right.
Without inhibitor; test period, 8 weeks
Left. With inhibitor, 0.1 % filepasin-sulfamido-sodium acetate; test period. 8 months
might create similar conditions a t the inlct valves. Tests should be made to ascertain whether the octane number of the fuel, especially when leaded, and other physical properties alter upon addition of such compounds..
If t,hese difficulties should appear with the sodium salt of the hydrocarbon-sulfamidocarboxylic acids, then, from the chemical point of view, it remains t o avoid t'he separation of low volatile inorganic compounds; at, least, to limit it extensively by use of the ammonia or cyclohexylamine salts of the same acids. Under present conditions these compounds are available only a t the moment the production of the acid starts. Information w a s rc-
H
0
34. SO2 .N.CH2. C . OH
H o / N = Mepasin residue
-
According to the solubility of these metal-active compounds in fuels, water, and diluted aqueous salt solutions, and t o the favorable dist,ribution ratio corresponding to the aggressiveness in both phases, a n adequate protection for the metal surface is produced in every phase independent of special conditions; in particular the two phases may exist from the beginning or they may be formed in the course of time-e.g., by repeated tanking or by condensation of water vapor. The distribution of sulfur and sodium between gasoline and water phase with 1% Mepasinsulfamido-sodium acet'ate added is given in Table I1 and Figure 12. The presence of t,he inhibitor guarantees the protection, even when the surface is damagcd, for immediately t,he protecting film is restored. According t o these favorable properties the preparation of corrosion-proof fuels will be most important for the aviation, automobile, and fuel industries. Therefore, other essential motivcs must be considered in the experimen'm. The small quantities of rasidues formed are unimportant !\-hen such corrosion-proof fuels are used in jet propulsion units. It might occur, however, that in combustion engines certain amounts of sodium sulfate would, because of the combustion process, Comdete oxidation
CllHSl, SO2,KH . CH2COOP;a -+
17C02
+
17"20
SOn
+
1/2
4Na2SO4
(Inorganic residue: sodium sulfate) originate disagreeable deposits on the outlet valves or cylinder walls. Likewise, the relatively low volatility of the compound
Figure 9. Corrosion within Water Phase (Bottom) of RIagnesium Container
November 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
I
40
IO
60
2621
80
TEST P E R I O D
100
120
140
160
,D A Y 5
Figure 11. Metal Corrosion by Water-Contaminated . Leaded Gasoline at Ambient Temperature Gasoline Type R72 Octane (Standard Oil C o . of Texas); inhibitor
Figure 10. Left.
1
Aluminum (Alcoa 25) Containers after 11-Month Test Period
R i g h t . Without inhibitor With inhibitor, 0.075 % Mepasin-sulfamido-sodium acetate (the seams are not properly welded)
ceived that the General Aniline & Film CorpoIation, New York, has started research on these compounds. They call the product “Emulsifier STH” and intend to use it for the preparation of emulsifying lubricants for light and heavy metal machinery. A sample was tested very carefully and it was found that the qualities are the mine as for the German product, not only as to the stability of the emulsion but also as t o the corrosion-inhibiting effert. The only difference will be that General Aniline & Film Corporation does not start nith Mepasin but with the corresponding fraction of the natural oil base of this country. The sodium salt of hydrocarbon-sulfamidoacetic acid was produced in Germany on a large scale during the last few years of the war (1942 to 1944) from Mepasin (production in 1944 about
without
Figure 12. Distribution, Ratio of Mepasin- SulfamidoSodium Acetate between Gasoline (Upper) Water (Lower)Phases Figures represent percentage of N a and S i n the different phases when their original amounts i n the inhibitor are set as 100 for each. After addition of 5 % water only the main portion of the inhibitor i a found in water phase. More water doesn’t give substantial alteration
4000 tons), as already mentioned a certain fraction of hydrocarbons gained by the Fischer-Tropsch synthesis. Thesc compounds have a chain length of about 12 to 18 carbon atoms and cannot be used as fuel for automobile motors because of their high boiling point; neither are they suitable for lubrication. TABLEI. METAL CORROSIONBY WATER CONTAMINATED By reaction of Mepasin with sulfur dioxide and chlorine in LEADED GASOLINE AT AMBIENT TEMPERATURE ultraviolet light, the monosulfochlorides of these hydrocarbons (R72 octane, Standard Oil Co. of Texas) are produced. This reaction has to be stopped when about 50% Corrosion Rate, Mg./Sq. Dm./Day of the Mepasin is converted. If the sulfochlorination is con__Without Inhibitor With Inhibitor rest __ tinued the output of Mepasinsulfochloride is not increased but Period, Water Fuel Vapor Water Fuel Vapor Days phase phase phase phase phase phase the reaction product varies by formation of higher sulfochlorinated compounds. The Mepasinsulfochloride is in turn transIron formed to sulfamides by succeeding reaction with ammonia. 0 0 0 8 21 Q3 0 5 24 o0 0 0 0 20 lo 621 0 5 By heating the sulfamides with monochloroacetic acid the hy225 3 5 0 0 0 40 62 0 so 42 2 176 3 4 0 0 0 06 drocarbon-sulfamidoacetic acid is formed. From this, the so160 33 1 17 6 3 5 0 03 0 0 06 dium salt may easily he produced. A mixture of about equal Magnesium parts of Mepasin-sulfamido-sodium acetate and unchanged ~
3.0 4.0 3.5 4.0
10 20 40 60 80 160
~
TABLE11. DISTRIBUTION OF SULFURAXD SODIUM BETWEEN ...
...
...
0
0
0
Aluminum Same kind of corrosion as with iron (uniform, no points and dots) the principal difference being t h a t i t amounts to a tenth of it only.
Iron Aluminum Magnesium
Inhibitor Mepasin-Sulfamidoacetic Aoid-Sodium Salt, Part 0.05 0.075 0.10
GASOLINEAND
170 MEPASIX-SLLFAhfIDOSODIUMACETATE ADDED
WATER PHASE WITH
Portions. Vol. Gasoline Water
Gasoline Phase %S 0.0011 0.0022 0,0022 0 0025 0 0029 0.0015 0.0023 0 002s 0.0023 0 0027 0.0020 0 0040 0.0022 0 0038 0.0018 0.0059
To Na
Water Phase
% Na
% S
0: 392 0.237 0.176 0.142 0.105 0.059 0.033
0 : if0
0.132 0.135 0.091 0.065 0.043 0.035
2622
INDUSTRIAL A N D E N G I N E E B I N G CHEMISTRY
Mepasin is a slightly colored and a very efficient emulsifier known under the trade name Rohrmittel Hochst. The single steps of this process are explained by the followinp equations:
CONCLUSIONs
The data presented show that fuels inhibited by hydroriirhonsulfamidocarboxylic acids offer considerable advantage. Heretofore certain corrosion problems coilld be solved by means of special devicea; now, designers through the use of these new inhibitors can choose construction materials according to the best mechanical and thermal, but regardless of their corrosion, properties. That is true for production, storage, arid transportation (in tank cars, tank boats, portahle tanks, pipe lines, including pump stations, tanks in airplanes, etc.) as ncll as for the motor. Considering the large consumption of fuels, such prot,ecting additions promise great advantages in the future chemistry of fuels and propellarits. In order to obtain further progress, :i&litional research and development work are desirable and necessary. hCKNOWLEDGB.IENT
The results of these investigations beginning in the middle thirties at the scientific laboratories of the former I. G. Farbenindustrie Bitterfeld were made possible only by the energetic assistance of all research departments concerned. Therefoie, the authors have to thank not only their co-worlrera, especially Fritz Henneberger, but also the folloning scientists who have promoted this development either by their own expel iments, designing propositions, or by placing suitable chemicals a t our disposal: the late Ludn ig Teichmann, Leverkusen; Walter von Freyberg, Hans Lange, Fritz Orthner, and Georg Schulz, Frankfurt-Hochst; Paul Heisel, Gersthofen; and Ernst de Ridder, former chief designer of the light metal department, Bitterfeld. Experimentation carried out in this country was largely supported b j Sergeant Thomas J. O’YcilI to whom the authors are cordially obliged, The authors also would like to thank the Office of the Chief of Ordnance, especially Colonel €1. N. Toftoy and Major J. P. Hamill, for their assistance and the permission to publish this report. LITERATURE CITED
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