INDUSTRIAL AND ENGINEERING CHEMISTRY
1990
Dewigne, G., M h . poudres, 30,59-68 (1948). Dunning. W. J., and Nutt, C. W., Trans. Faraday SOC.,47, 15-28 (1951).
Edwards, G., J . Roy. Tech. Coll. (Glasgow), 5, 122-7 (1950). GillesDie. R. J.. Huahes. E. D., and Ingold. C. K., J . Chem. Soc., 1950, 2473-93; 2493-2503; 2532-7; 2 5 3 7 4 2 ; 2542-51.
-
2504-15;
2516-31;
Glazer, J., Hughes, E. D., Ingold, C. K., James, A. T., Jones, C. T., and Roberts, E., Ibid., 1950, 2657-78. Gold, V., Hughes, E. D., and Ingold, C. K., Ibid., 1950,2467-73. Gold, V., Hughes, E. D., Ingold, C. K., and Williams, G. H., I b X , 1950, 2452-66. Grundmann, C., and Haldenwanger, H., Angew. Chem., 62, 5568 (1950).
Halberstadt, E. S., Hughes, E. D., and Ingold, C. K., J . Chem. SOC.,1950, 2441-52.
Heertjes, P. M., and Revallier, L. J., Research, 3, 286-8 (1950). Hodgson, H. H., Heyworth, F., and Ward, E. R., J . SOC.Dyers Colourtkts, 66, 229-31 (1950).
Hughes, E. D., Ingold, C. K., and Reed, R. I., J . Chem. SOC., 1950, 2400-40.
Hughes, E. D., and Jones, C. T., Ibid., 1950, 2678-84. Ineold. C. K.. Goddard. D. R.. and Hughes. E. D.. Ibid., i9&,2559-$5.
Ingold, C. K., Millen. D. J., and Poole, H. G., Ibid., 1950, 2576s 9 : 2589-2600: 2600-06: 2606-12: 2612-19: 2620-7. (27) Israeiashvili, S., Gature, 165,'No. 4200, 686 (1950).
Vol. 43, No. 9
(28) Jeasup, R. S., and Prosen, E. J., J . Research -Vatl. Bur. Standards, 44,387-93 (1950). Krata, B., Wasser, Vom, 17, 83-8 (1949); C ' h m . d b s . , 44, 8030 (1950). Lowen, A. M., Murray, M. A., and WiIlian~>, G . , J . Chem. SOC., 1950, 3318-22. Maillard, A., and Arbogast, R., Compt. w d , 231, 1237-8 (1950). Rosenthal, A,, and Brown, R. K., Pulp h Paper Mag. Can., 51, No. 6, 99-105 (1950). Stengel, L. A. (to Commercial Solvents C ' O Y ~ . U. ~ . S. Patent 2,512,587 (June 20, 1950). Thinius, K., Chem. Technol., 1, 101-7 (19491: Chem. Abs., 44, 4245 (1950). Todinson, W. R., Jr., and Groggins, P. H., f'h#vt. Eng., 57, No. 12, 131-3 (1950). Von Schickh, O., Angew. Chem., 62, 547-56 !1950). Vroom, A. H., and Winkler, C. A., Can. J . Rr.warch, 28, Sect. B, 701-14 (1950). Watanabe, S., J . SOC.Textile Cellulose I d w t r g , Japan, 1, 63641 (1945); Chem. Abs., 44, 6117 (1950). Williams, G., and Lowen, A. M., J . Chem. Soc., 1950, 3312-18. Willson, F. G., Aguila, F., and Roberta, E. (to Minister of Supply in His Majesty's Government of the U. K. of Great Britain and Northern Ireland), G. S. Patent 2,525,252 (Oct. 10, 1950).
RECEIVED June 13, 1951.
OXIDATION E0c
L. F. MAREK
ARTHUR D. LITTLE, INC., CAMBRIDGE, MASS.
O x i d a t i o n processes, both destructive and constructive, are of enormous importance in industry. Destructive oxidation, evidenced by corrosion of metals, deterioration of paint, rubber, a n d plastics, burning of forests and structures, and the various objectionable effects noted in chemical processing, represents a force to be combatted. Constructive oxidation plays an important role i n the conversion of hydrocarbons to useful chemicals, the transformation of chemical intermediates to more desirable compounds and the controlled utilization of combustion energy. I t represents a force to be directed and controlled for economic purposes. If any area of oxidative processing were to b e singled out for attention, i t would b e that represented by conversion of hydrocarbons to useful organic chemicals both because of the scale of present exploitation and the enormous prospects for the future. Products such as phthalic anhydride, maleic anhydride, ethylene oxide, adipic acid, acrolein, aliphatic aldehydes and acids, certain hydroperoxides, gas mixtures for synthesis of hydrocarbons, oxygenated organic compounds, and ammonia, and others are currently produced by oxidation of hydrocarbons, some on a very large scale. Since there is always room for improvement in yield and reduction of cost, a steady stream of research and development effort i s being poured into this segment of the chemical process industry. Future prospects lie in the adaptation of processing t o new raw materials for products currently made from raw example, oxidation of aromatic hydrocarbons other than materials of limited supply-for naphthalene to phthalic anhydride) oxidation of hydrocarbons for production of chemicals example, oxidation of propylene to acrolein) manufacusually made by other routes-for ture of hydrogen peroxide and other peroxides via hydrogen or hydrocarbon oxidation, formation of ethylene and acetylene from hydrocarbons by oxidative dehydrogenation or autothermal heating) and brand-new areas of development not yet described in the technical literature.
R
EVIEWS of the progress made by petrochemicals in recent
years disclose that upwards of 40% of our organic chemicals production stems from crude oil and natural gas hydrocarbons. Of the primary processes for conversion of hydrocarbons to chemicals @4), oxidation continues to hold a n important place.
ALIPHATIC HYDROCARBONS
chemicals would beerected in Canada. It has also been reported that the corporation will erect a similar plant in the Texas Panhandle to increase its sup;dy of the cheniicals used in manufacture of cellulose acetate. Up to this writing, the McCarthy Chemical Co. plant a t Winnie, Tex., has not been reactivated for use in oxidation of natural gas hydrocarbons, although considerable interest has been shown by various companies in the prospects for conversion of the facility to some process modification that had better earning possibilities. Although the commercial outcome of the major scale Fischer-Tropsch synthesis plant operated by Carthage Hydrocol, Inc., a t Brownsville, Tex., is still uncertain, considerable interest continues to be shown in development of processes for conversion of natural gas hydrocarbons to synthesis gas. One direction taken in such development has been to make use of metal oxides, capable of regeneration by air, as the oxidizing reagent to avoid the need of a n oxygen plant or to avoid the nitrogen dilution introduced when air is used directly. Of course, where the synthesis gas is to be used for ammonia synthesis, introduction of nitrogen dilution is acceptable. Among the met.al oxides that havebeen considered suitable for such a process are the oxides of iron, cobalt, chromium, nickel. molvbdenum. manganese, vanadium, and titanium, alone or in mixtures: Titania is claimed tQ be superior to iron oxides because of less carbon dioxide formation but requires the admixture of certain I
During the year, Celanese Corp. of America announced that a plant based on a process similar to t h a t employed by the corporation at Bishop, Tex., for the air oxidation of propane to a group of
_
September 1951
INDUSTRIAL A N D ENGINEERING CHEMISTRY
of the other oxides to attain reaction rates of industrial interest (87). The efficiency of reaction of methane, with metal oxides to form synthesis gas, has been found to be materially increased by use of an alkali catalyzer, such as sodium carbonate (89). Fluidized solids techniques have been applied to proceases such as the above, and also for heat transfer where gaseous oxidanb of methane are employed (40). Pilot plant studies of a process for the formation of ethylene by autothermic cracking of ethane and propane have shown t h a t the process is operable a t higher conversions and less recycle than thermal P>TO~YS& in tubular reactors. By this process the endothermic (SI) heat of cracking is offset by introduction of air or oxygen with hydrocarbon feed to make the over-ail reaction selfsustaining. With ethane a t 80% per pass conversion t h e product gas stream contains: & 2 1 % ethylene, 19.8% hydrogen, and 38.3'%nitrogen. With propane at 80% per pass conversion the product gas stream contains: 18% ethylene, 5% propylene, 9 . 6 % hydrogen, and 33y0 nitrogen. Either oil absorption or hypersorption techniques may be used for olefin recovery. I.G. Farbenindustrie practice at Leuna has been described (17). Oxidation of paraffins in the range between 20 and 35 carbon atoms per molecule under suitable conditions is claimed to result in formation of succinic acid and succinic anhydride (75). Batchwise oxidation of n-hesadecane, for example, was found to yield 2.5 parts succinic acid per 100 parts of hydrocarbon. In the slow combustion of n-hexane, higher aldehydes and formaldehyde are formed in nearly equivalent amounts, presumably by the decomposition of initially formed hydroperoxides. %action mechanism (28) studies with 50% n-butane-xygen, 50% n-pentme-oxygen, and 30% n-hexane-oxygen in the cool &me region of reaction have been reported. The suggested correlation of pressure-temperature and induction period limits (67) permits one to reduce, to comparative order, previously reported coherent data on hobflame ignition curves in the relatively low temperature region. One of the major problems in the useful oxidation of the higher molecular weight hydrocarbons is t h a t of product recovery. An improvement is claimed to result from the use of means whereby the oxidized oil is first. treated with alkali or alkaline earth hydroxide solution, to convert peroxides and remove acids as water-soluble salts, and is then extracted with solvents of the class including liquid sulfur dioxide, phenol, acetonitrile, and the like (59). One advantage claimed for this recovery procedure is its applicability to oils wherein oxidation has proceeded to as high as 70% conversion of the original hydrocarbon charge. Noncatalytic vapor-phase oxidation of naphthenic hydrocarbons with air has been claimed to result in high yields of naphthenic acids together with oxygenated naphthenes, alcohols, aldehydes, esters, and ketones. Oxygen concentrations between 0.5 and 2.0 molal proportions and carefully controlled temperature and pressure conditions result in yields up to 40% of oxygenated products (32). Mechanism studies of the oxidation of methyl cyclopentane have shown the complex interrelationship of pressure and temperature along the ignition limits. Peroxides are found in the products of low temperature reaction (13) and chiefly acids and carbonyl compounds at higher temperatures. Limited oxidation of methane and ethane may be effected directly by means of concentrated sulfuric acid and of sulfur trioxide without use of air or 02,With silver, copper, or cerium compounds as catalysts (66), oxidation at temperatures approximating 300" C. results in yields of 75 to 85% formaldehyde from methane. A literature review of ethylene oxide indicates i t to be a n organic intermediate of vast potentialities in the chemical industry. It has already attained a position of considerable significance and as a result there is increasing interest in methods of manufacture. A recent review by one manufacturer, Jefferson Chemical Co., is of interest, since the chlorohydrin, direct oxidation, and formaldehyde routes (63) are all mentioned.
1991
Work on the direct oxidation of ethylene to ethylene oxide has been continued by the National Research Council of Canada. Cooperative experimentation has been done by Polymer Corp. at Sarnia with premures u p to 60 pounds per square inch in an effort to improve heat transfer rates and hence reactor capacitim. Although a fluidized catalyst bed technique has been developed (Atlantic Refining Co.) for the direct oxidation of ethylene to ethylene oxidation, no commercial practice has resulted to the present. The increasing costs of ethylene have served to limit the extension of the direct oxidation route and improved processes which would result in higher yields are much sought after. The hazards and methods of handling of ethylene oxide have been reviewed (48). Liquid ethylene oxide is stable to common detonating agents. Ethylene oxide vapor explodes when exposed to various ignition sources. Processes suitable for oxidation of ethylene to the oxide are not effective for production of propylene oxide. React'ion zones containing an appreciable area of gas-contacting surface coupled with superatmospheric pressures have been found to improve yields of propylene oxide in the direct oxidation of propane, propylene, or mixtures (966). Molal ratios of hydrocarbon to oxygen in the range of 3 to 8 give best efficiencies with hydrocarbon recycle. Copper and silver are to be avoided and stainless steel and aluminum are best reactor materials. Nonporous packing must be used. The direct. oxidation of propylene to acrolein by Shell Chemical Co. is rumored t,o be by a process in which propylene plus air or oxygen plus a moderate catalyst poison is passed over a copper oxide catalyst. The process converts olefins of three or more (19) carbon atoms per molecule into vinyl-type aldehydes or ketones and reputedly was responsible for the drastic price reduction of acrolein in 1950. Details of the process are not available. Oxidat,ion of cis-Zbutene with air over catalysts of the S'ZOSMoos type is claimed to result in substantial y i e b of maleic acid-maleic anhydride. Hydrocarbon concentrations up to 3 to 4% by volume in air and operating temperatures of 340" t.0 350" C. are stated t o be most desirable (7). I n experiments on the oxidation of 1-butene induced by aluminum borohydride, it was found t h a t reaction occurred in Chi? absence of oxygen. Boron alkyls were found in the reaction products ( l a ) . In the polymerization of olefins over catalysts such &s phosphoric acid or phosphates, oxygen contained in the olefinic feed stock in small amounts may be effectively removed by passing the feed over oxidation catalysts such as vanadium oxide. Such conversion (91) of molecular oxygen to oxygenated compounds is claimed t o increase materially the life of the polymerization catalyst. Catalytic Combustion Corp. has developed equipment for the catalytic combustion of hydrocarbon fumes which makes use of a platinum-group catalyst effective at temperatures of the order of 500" F. Similarly, catalytic combustion can be used for disposal ( 2 1 ) of air pollution containing any combustible vapors (8.9).
AROMATIC HYDROCARBONS Oxidation Kith molecular oxygen of benzene dissolved in liquid hydrofluoric acid in the presence of promoters or oxygen carriers, such as oxides of silver, arsenic, or selenium, has been claimed to give 100% yields of phenol a t conversions on the order of 2% (84). Similarly, toluene gives o-cresol, naphthalene gives 2naphthol, and m-xylene results in 7Oy0 to 2,4-dimcthylphcnol and 20y0 to m-toluic acid. The current benzene shortage is discouraging to proccsscs for direct oxidation to phenol, previously reviewed in this series, because of the characteristically low conversions which were \wing obtained.
1992
INDUSTRIAL AND ENGINEERING CHEMISTRY
The importance of terephthalic acid as a raw material in the manufacture of synthetic textile fibers has led to considerable interest in commercial methods of production. In general parasubstituted benzene hydrocarbons serve as starting raw materials. Stepwise oxidation has frequently been advocated in the literature. p X y l e n e and p-cymene are characteristic raw materials. Oxidation of a benzene monocarboxylic acid possessing a n alkyl group para t o the carboxyl group, in the liquid phase with a n oxygen-containing gas at temperatures of at least 370' F., is claimed t o result in formation of a terephthalic acid (87). I n the case of a benzene monocarboxylic acid possessing a n alkyl group meta to the carboxyl group, the same process results in formation of a n isophthalic acid (86). Inweases in phthalic anhydride production tend to be limited by the availability of naphthalene, and substantial imports of this raw material have occurred. Petroleum-derived o-xylene seems to be the best solution of the raw material supply situation, but the problems associated with manufacture of phthalic anhydride from o-xylene act as deterrents. Phthalic anhydride production in 1950 was approximately 212,000,000 pounds from a n industry annual capacity estimated at 220 t o 230 pounds. Barrett Division of Allied Chemical & Dye Corp. is reported t o be installing a plant with a capacity of 20,000,000 to 25,000,000 pounds and costing $45,000,000, near Chicago, t o use naphthalene as raw material (71). Other producers are reportedly improving present facilities to increase production. The use of a fluidized catalyst bed in the oxidation of naphthalene or p-xylene t o phthalic anhydride is claimed t o result in superior operating control with consequent better yields (78). Preparation of colloidal aqueous suspensions of vanadium ~ 850" C. into vigorously stirred oxide, by pouring molten V Z Oat water at 20" C. until 1.5% concentration is reached, is advocated as a simple means of preparing the active material for coating selected supports (26). Manganous naphthenate has been found to be unusually effective in promoting the oxidation of ethyl naphthalene t o methyl naphthyl carbinol and methyl naphthyl ketone. At temperatures of 100' to 125' C., conversions of 20 t o 3oy0 are obtained, with air as oxidizing agent (57). In a n experimental fluidized reactor the British Coal Utilization Research Association has obtained 60% yields of phthalic anhydride by oxidation of phenanthrene (14). Present production of maleic anhydride is derived h 35 t o 40% yield as a by-product from phthalic anhydride manufacture, 35 t o 40% by oxidation of benzene, and 20% by oxidation of butenes (23). Pyridine carboxylic acids are obtained b y the catalytic oxidation of heterocyclic aromatic nitrogen compounds having a n oxidizable organic group attached t o the N-contaifing aromatic nucleus by one or more G-c bonds. The process consists of reacting nitric acid as oxidizing agent with the N-heteroaryl compound dissolved in a sulfuric acid solution of a catalytic metal salt such as mercury or copper sulfate. Examples include nicotine t o nicotinic acid (89),8-hydroxy quinoline to quinolinic acid, and 4-picoline to isonicotinic acid.
OXIDATION OF ORGANIC COMPOUNDS I n the usual process of oxidizing methanol to formaldehyde with air over metal oxide catalysts where lean mixture conditions are used, methanol concentrations below the explosive limit of 6.7 volume yo methanol must be used. Stepwise introduction of methanol t o the reaction mixture flowing through a series of catalyst zones has been suggested t o permit attainment of higher product concentrations than obtainable in the single stage process (57). Examples of effective phosphorous catalysts for methanol oxidation consist of phosphates of manganese, magnesium, cadmium, or a n alkaline earth metal promoted with molybdic oxide and containing in addition a dialkali metal phosphate or an alkali metal carbonate. Composition examples in-
clude atomic ratios (58) of: 1Mn
0.9P
- 0.2M0.
Vol. 43, No. 9
-
1P - 0.3Mo and 1Mn -
Some of the characteristics of preparation and use of silver catalysts have been recently reviewed on the basis of British practice (18). T o take advantage of the good features of the two general systems of methanol-to-formaldehyde conversion, a process has been devised whereby a first stage consists of oxidation and dehydrogenation using a methanol-rich mixture over a silver catalyst and a second stage of oxidation using a metal oxide catalyst (73). Examples show the major conversion of methanol t o be i n t h e first stage with the second stage used to clean up the remaining methanol. By this combination of steps it is possible to produce 60% formaldehyde solutions free of methanol without sacrifice of yield or excessive equipment. A continuous process for the ovidation of acetaldehyde t o acetic anhydride provides for the injection of technical grade oxygen into a continuously circulated stream of liquid reaction mixture containing acetic acid, acetic anhydride, acetaldehyde, and a dissolved catalyst. Catalysts such as copper and cobalt acetate mixtures are shown in examples (55). Surprisingly low concentrations only of per compounds were found in the product. Recovery of acetic anhydride from the reaction product mixture is achieved by fractionation in a packed column at a pressure between SO and 200 mm. of mercury with kettle temperatures above 70" to 75" C. t o destroy per compounds ( 4 3 ) . The ignition characteristics of acetaldehyde-air and acetaldehyde-oxygen systems together with the limits for flame propagation in acetaldehyde-oxygen-nitrogen systems have been reported (09). Comparative studies of the effectiveness of cobalt and manganese propionates as catalysts for the liquid phase oxidation of propionaldehyde t o propionic acid have been reported t o show t h a t the latter is superior t o cobalt (60). Best conditions gave conversions of 75% with acid yields of approvimately 90% based on aldehyde consumed. Optimum catalyst concentration was in the range of 50 to 100 parts metal per million parts aldehyde. The oxidation of ethyl acetate to acetic acid provides a route t o acetic acid from ethylene pithout gqjng through the ethanolacetaldehyde sequence, since ethylene may be reacted directly with acetic acid by any one of several ways. Yields of 80 to 90% of theoretical are claimed for a process of liquid phase ovidation of ethyl acetate with oxygen at pressures of 100 t o 500 pounds per square inch and in presence of catalysts a s cobalt naphthenate ($5). Glyoxal is manufactured commercially by the ovidation of ethylene glycol in presence of a copper oxide catalyst. Oxidation (10) reactions t o formaldehyde, carbon dioxide, and water are suppressed by t h e action of certain halogen compounds on the catalyst surface, resulting in high glyoxal-to-formaldehyde yield ratios. A vapor-phase process is used with make-up air and glycol being added to the cycled inerts and the inhibitor is added via a side stream of nitrogen as near the reactor a s possible. A shell and tube heat exchanger type reactor containing 745 Hastelloy B tubes 1.03 inches inside diameter by 10 feet long filled 9.5 feet with catalyst is used. Catalyst consists of 2 by 4 mesh Aloxite impregnated with copper nitrate t o give a copper content of 3 t o Syoafter roasting. Catalyst life is a year or more. The presence of between 70 to 300 parts of cobalt as metal per million parts of manganese acetate in manganese acetate-barium acetate catalysts has been found to give optimum activity in the oxidation of cyclohexanone to adipic acid. This ovidation process is performed (61) at substantially atmospheric pressure, a t temperatures of 85" to 95" C., and with on the order of 30% concentrations of cyclohexanone in a n organic acid such as acetic, propionic, or butyric. The effect of the cobalt addition is mainly toward increasing reaction rate, yields remaining about the same at A70 yorecovered adipic acid for various added proportions. Air oxidation of nonconjugated liquid fatty mono-olefin or
September 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
polyolefin compounds which are acids, amides, or esters in the presence of catalytic amounts of selenium, tellurium, or their derivatives is claimed t o yield oxygenated products. For example (88),linseed oil &- made to yield a mixture of hydroxylated and other oxygenated linseed oil. Selected liquid phase, catalytic oxidation applied t o the product from an oxo process synthesis is claimed t o result in a product in which the branched-chain compounds are converted t o acids which may be extracted by a saponification procedure and the more straight-chain products are converted t o neutral compounds which may be solvenbextracted. Catalytic metal soaps such as cobalt oleate (36) are suitable for the promotion of the oxidation reaction. Tartaric acid is said to be formed by the hydrogen peroxide oxidation of maleic anhydride in presence of a tungsten oxide catalyst (81).
PEROXIDES The military significance of high strength hydrogen peroxide (80% and above) continues t o attract attention (16). Such possibilities as a peroxide-driven submarine, take-off assistance for jet propelled airplanes, and other uses have been mentioned. The de Haviland Sprite assisted take-off unit is stated t o be charged with 40 gallons of peroxide plus permanganate catalyst and compressed air. Such uses have induced continued study of processes other than the electrolytic persulfate or persulfuric acid processes. Among the processes being studied are those based on reaction of oxygen with hydrogen or natural gas hydrocarbons. Little information has been published. Special fractional distillation procedures permit the ready attainment of pure hydrogen peroxide of concentrations up to 98% (94). In the partial oxidation of propane, n-butane, or isobutane, at ratios of a t least four volumes hydrocarbon vapor per volume of oxygen, it has been found t h a t a t temperatures below a certain level aldehyde formation greatly exceeds hydrogen peroxide formation but that a t higher temperatures the reverse occurs and hydrogen peroxide formation predominates over aldehydes (46). Thus, in the case of 95 b u t a n e 5 oxygen mixtures about 65% of the oxygen reacted under the conditions at 460" C. t o give a product gas stream containing 1.2 volume % Hz02 and 0.4 volume % CHZO. At about 390" C. and the same proportion of ovygen reacted the product gases contained less than 0.4 volume % of HzOzand 1.6 volume % CH20. The production of hydrogen peroxide by the cyclic hydrogenation and oxidation of alkylated anthraquinones has been reported to have been extensively worked on in Germany during the war and developed to substantial pilot plant stage. Studies in this country of the process have shown some of the problems, among them the excessive consumption of Raney nickel catalyst for the hydrogenation. However, improvements continue to be sought. One direction of improvement has been toward the use of more desirable solvents than benzene, which is usually used. Disubstituted organic esters of a phosphoric acid and trisubstituted organic esters of phosphoric acid have been claimed (50). As part of a government research program t o increase utilization of turpentine as a chemical raw material, studies have been made toward formation of peroxides (3'9). Turpentine and many terpenes spontaneously form peroxides on exposure to air. These peroxides are similar t o those used incfustrially as polymerization catalysts. Thus, the peroxide catalysts required for the production of 760,000 tons GR-S in 1951 would provide a market for some 500,000 gallons of turpentine, releasing equivalent amounts of benzene. The above program resulted in development of a satisfactory process for production of peroxides from terpene and hydrogenated terpene hydrocarbons. Of these products pinene hydroperoxide and menthone hydroperoxide were found useful and superior as catalysts for the cold GR-S process. Oxidation was
1993
accomplished by bubbling oxygen through the heated liquid while illuminated by electric lamp bulbs suitably placed. Peroxide recoveries of over 90% were achieved by low pressure distillation from unreacted hydrocarbon. It has been previously reported in this review that decomposition of certain of these peroxides lead to seemingly useful commercial processes. Thus, cumene hydroperoxide decomposes with resultant SO% yields of equimolar proportions of acetone and phenol. Similarly, methyl cumene hydroperoxide decomposes t o acetone and cresol. Hercules Powder Go. is reported t o be constructing a plant t o operate such a process based on peroxidation of cymene in conjunction with other operations using turpentine hydrocarbons for manufacture of Toxaphene insecticide ($0). It has recently been announced that a Canadian plant to be erected by British American-Shawinigan, Ltd., jointly owned subsidiary of British American Oil Co. and Shawinigan Chemicals, Ltd., will produce phenol and acetone under Herculea Powder-Distillers Co. patents. The over-all process will involve alkylation of benzene with propylene to form cumene, oxidation to the hydroperoxide, and splitting to phenol and acetone. Also, Barrett Division of Allied Chemical & Dye Corp. is reported to be planning an $8,000,000 plant near Philadelphia t o produce 25,000,000pounds of phenol per year based on cumene. European enterprises are also interested. Oxidation of tetralin with molecular oxygen a t temperatures of about 60" t o 90" C. results in formation of Tetralin hydroperoxide, containing chiefly 1,2,3,4tetrahydronaphtha1enel-hydroperoxide. Product recovery may be by vacuum distillation or by crystallization of the peroxide alkali metal salt followed by acidification. Pentane or heptane extraction of crude concentrate is claimed t o result in a pure hydroperoxide (93). The alkali metal or alkaline earth metal salts of tertiary organic peroxides may be reacted with unsaturated halides to produce compounds of the type RI-O-O--B2, when R stands for either the tertiary organic radical or the unsaturated aliphatic or cycloaliphatic radical. These products are claimed to be useful as polymerization catalysts (79). For the formation of dopes for Diesel fuels the reachon o f tertiary hydroperoxides with organic compounds containing a keto group in presence of an inert solvent has been described. For example ( 7 4 ) , the reaction of methyl ethyl ketone with lerlbutyl hydroperoxide results in formation of 2,2-bis (tert-butyl peroxy) butane. Solvents such as benzene, heptane, or pentane at volume ratios of 1 t o 10 of the combined reagent volume have been found suitable. Hydrochloric acid is a satisfactory catalyst at 5 volume yo.
O X I D A T I O N OF CARBON Oxides of metals such as cobalt, nickel, mangancv, iron, or copper can function in a regenerative cycle vvheieby carbon is oxidized t o carbon dioxide without nitrogen dilution. Ferric oxide and cupric oxide have been studied for this purpose in a fluidized powder bed. Cupric oxide coated on silica gel proved to have poor durability ( 6 $ ) , copper separating and either collecting as clumps in the reactor bottom or blowing out as finrhs. Cupric oxide gives desirable reaction rates but ash from the carbon contaminates the metal oxide. Using hematitic iron ore and coke in a reactor 2 feet in diameter by 20 feet tall, it was possible to operate at a rate to give 10 to 15 tons of carbon dioxide per day. More active carbon would give higher rates. Although iron appears satisfactory in the process only limited regeneration experiments were made. A survey of previous experiments dealing with t h e investigations of primary combustion products of carbon together with data from experiments based on a method developed in Central Laboratory, Staatsmijnen, Geleen, Netherlands, leads to a conclusion that carbon monoxide is the primary gaseous reaction
1994
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
product. Traces of ozone were found under conditions which precluded presence of nitrogen oxide (89). Illinois State Geological Survey experiments confirm the “Russell effect” whereby perosidized coal produces photographic images (96). The British Coal Utilization Research Association has studied the effects of several additives to fuel and to oxidizing gases on the composition of exhaust gases from burning carbon tubes and on carbon monoxide flames. Substances with strong affinity for hydrogen or water increase ( 2 ) the proportion of monoxide t,o dioxide in combustion products from carbon tubes and, when added to carbon monoxide flames, they decrease the partial pressure of hydrogen in flames. Most of the inhibitors were halogens or volatile halides. When inorganic halides were added to the fuel only small inhibiting effects were observed, .4study of the reactions in fuel beds in active combustion and ol the manner in which oxygen is consumed has been applied to the design of the Downjet furnace in which no metal grates are used and which when burning coke can produce nearly theoretical yield of carbon dioxide with no excess osygen (1). Since large deposits of low grade coal are known t o be available, experiments have been conducted near Sheffield, England, on underground gasification (16). No immediate evidence of p s s j ble profit, however, is reported from these experiments.
RUBBER OXIDATION As evidenced by recent publications of results from experimental work, the study of osidat,ive det’erioration of rubber continues to receive attention. The nature of accelerators of vulcanization and antioxidants is important in characterizing the aging properties of vulcanized rubber, affecting both the rate of oxygen uptake and the nature of the reaction of oxygen with rubber. The importance of chain transfer reactions has been emphasized in interrelation of reactions occurring during oxidation and vulcanization. New equipment permitting the simultaneous determination of oxygen uptake a t constant pressure and of the deterioration in stressstrain properties at low elongations (5) has been used in some of these studies. The conventional 0.075- to 0.080-inch thickness samples are frequently not satisfactory for accelerated aging and oxidation studies if limitations due to diffusion are to be avoided. Data have been presented (9) to help in selection of proper sample thickness in such studies for both constant-rate and autocatalytic stages of oxidation. By the action of substances like mercaptobenzimidazole alone and with thiourea, thioacetamide, some dithiocarbonates, and aromatic mercaptans in the presence of peroxides, added or already present, it is possible to mill rubber relatively easily t o either a state of “normal plasticization” or t o a viscous liquid. Reactions involved in this phenomena have been discussed (68). The effect of mercaptobenzimidazole (MBI) on aging of rubber in relation t o cure has been studied on the basis of volumetric oxygen absorption. The time of cure has relatively little effect on rate of oxidation of natural or GR-S rubber (82)once a reasonable state of cure is reached. The superiority of combinations of M B I plus conventional antioxidants in giving age resistance t o rubbers is confirmed. Emulsion polymers of butadiene prepared a t -10” C., when subjected t o oxidation by permanganates, produced larger amounts of succinic acid and less tricaballylic acid relative t o polymers prepared at 50” C. This correlates with the thought t h a t lower polymerization temperatures result in polymers of more regular structure and less branching (70). A chromatographic scheme was used in analysis of the oxidation products. I n an effort to circumvent some of the complexities involved in mechanism studies of rubber aging, a program of research at Case Institute of Technology has been directed to studies of the
Vol. 43, No. 9
oxidation of olefins representing some of the structural units of GR-5. Thus (90)liquid phase, autocatalytic, thermally activated oxidations with molecular oxygen of l-phenyI4hexane, 1-phenyl-3-pentene, and 2-octene-structurally related to GR-Shave been performed. The mechanism involves oxygen attack at the alpha methylenic group but attack can also occur a t double bonds giving peroxides and chain propagation. Various relationships are presented. Theoretical analyses and evaluation of rate constants for olefinic oxidations, photochemically induced, have been published by the British Rubber Producers’ Research Association. In addition to olefins such as 1-octene, gutta percha and rubber have been experimented with (4). Small amounts of oxygen have a deleterious effect on the ferrous redox systems in current use for manufacture of cold rubber and i t is recommended that great care be exercised in the complete elimination of mygen from the system. In experimental work, additions of 0.05 part of sodium dithionate as an oxygen scavenger gave improved rates of polymerization (62). The rate of oxidation of ammonia-preserved, natural rubber latex depends on p H of the latex, increasing as p H rises to a maximum of 10.4 and decreasing beyond. Rate of oxidation increases twofold for each 10” C. rise in temperature. Commercial latex is imported a t p H where oxidation is at highest rates (64) and exposure to air should be minimized and lower p H used if possible. Oxygen uptake is by both rubber and nonrubber components but in bacterially infected latex most of the uptake is by nonrubber components.
TRANSFORMER OILS Oxidation stability of transformer oils is of prime importance in use since chemical and electrical purity become impaired primarily by oxidation processes during use. The major final oxidation products are: sludge, acids and carbon dioxide, and water. Shell Refining and Marketing Co., Ltd., has reviewed various standardized oxidation tests and instituted a program for develop ment of more adequate tests (44). A procedure for the rapid evaluation of inhibited transformer oils is based on the measurement of rate of oxygen absorption, the absorption of loo0 ml. of oxygen per 100 grams of oil being used as the standard level. The method tends not to discriminate between uninhibited oils which have time requirements from 0.75 to 5 hours for the test and usually about 2 hours ( 8 ) . Amino and phenolic compounds were used as inhibitors and a variety of results from the experiments are given. OiL with oxidation rates above a certain limit oxidize a t the same rate under conditions where access of oxygen t o the oil is limited. When oxygen access is restricted oxidation rate is lowered and sludge formation reduced. In practice, the rate of oxygen diffusion into the transformer oil determines the rate of oxidation (66).
OXIDATION OF DRYING OILS Results from a study of the oxidation of raw linseed oil a t temperatures of 84’ to 200” C. indicate a free radical mechanism of oxidation and the formation of an intermediate prior to ovidative molecular weight increase. A chelate-type intermediate is speculatively proposed (49) and the suggestion made t h a t ovidative molecular weight increase may partially occur by association of intermediates to form double molecules by H-bonding. Comparative bulk ovidation studies of drying and nondrying oils show that the linolenic and linoleic segments of a triglyceride molecule (50) behave similarly upon oxidation in bulk, but that differences in oxidation behavior are to be noted for the oleic, eleostearic, and 9,ll-linoleic constituents. By spreading the drying oil over the very large surface of selected silica gels in oxidation studies at Mellon Institute, further insight into the mechanism of oxygen absorption by a drying oil is
September 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
obtained. Silica gel has the advantage for the purpose of not absorbing oxygen. TWO stages in oxygen absorption have been found depending on spread of the film ( 5 5 ) . Treatment with oxygen a t temperatures between 700" and 1OOO" C. of carbon blacks such as an MAF black, an HAF black, Philblack A, and Philblack 0 has shown that all p H values between 9.5 and 3 can be attained. Such surface oxidation of furnace blacks reduces the pH (24)and increases the volatile content and the surface area but does not necessarily involve any appreciable loss of volatile carbon oxides. Rubber-reinforcing properties of the oxidized blacks are reported.
KINETICS In a further effort to develop methods for determination of true burning velocity of propane-air mixtures, work a t the University, Birmingham, has been based on measurements in a region of the cone where disturbances are fewer. Results obtained are higher than those reported by other workers ( 4 1), -4detailed study has been made in the laboratories of Imperial Chemical Industries of conditions under which ignition of acetaldehyde vapor mixtures with air or oxygen occurs in the interest of drtcrinining causes of accident,al explosions and probable renieclies ( 9 2 ) . Peracetic acid is an important factor in the ignition of acetaldehyde mixtures a t heated surfaces and is probably important in flame propagation particularly in mixtures containing much aldehyde. ',Pre-reactions" may occur during the compression fitroke prior to igriition and include oxidation, cracking, and dehydrogenation of the original hydrocarbons, polymerization of the oxidation products, and formation of various types of oxygenated compounds. These pre-reactions vary with fuel, engine, and opera ting conditions. Aromatic-type fuels appear to resist these reactions, whereas paraffinic-type hydrocarbons have a pronounced tendency to pre-react ( 7 7 ) . Oxidations by photochemical electron transfer excitation were studied with monochromatic light of wave length 365 mp on aqueous solutions of benzoic acid in the presence of ferric ionpair complexes ( 6 ) . A method for determination of maximum fundamental flame velocities for a number of hydrocarbons in air by a tube method has been described (4%). Data are presented for a variety of hydrocarbons including normal and branched alkanes, alkenes, alkynes, cyclohexane, and benzene. The fundamental relations brtir ~ ~ ohydrocarbon i i structure and flame velocity are shown. Thci niasiniurn flame velocities for these hydrocarbons are coiisistent \vith the active particle diffusion theory of flame propagation. This theory predicts the observed trends in flame velocitj, with increasing chain length, degree of unsaturation, and methyl substitution (85). The reaction mechanism of autoxidation of conjugated o l e -steins is discussed. Fluorene hydroperoxide or fluorenone are orincd (,54)in the autoxidation of fluorene depending on temperature. Triphenylmethane on autoxidation yields relatively small amounte of triphengl hydroperoxide (63). ful design and operat,ion of certain types of aircraft j r t engines requires more knowledge in the field of chemical reaction speeds. Some of the factors involved have been descrilwd by the director of reeearch for the Acrojet Engineering Corp. (96).
MISCELLANEOUS Chlorination of methane with hydrochloric acid-oxygen mixtures has hccw studied as a process of potential interest for using by-product hydrochloric acid instead of chlorine in a modified Deawn-type reaction (68). Products under a variety of conditions consisted of the four rhloromethanes whose proposit,ions could he varied by changer in feed gas composition. Copper chloride catalyst was used in a tubular-type reactor a t temperatures of 400" to 550" C.
1995
The history and detailed description of the properties of chiorate candle oxygen generators have recently been published. Selfregulated thermal decomposition is due to the combustion of finely divided iron mixed with sodium chlorate (80). Glass fiber is used as a binder, barium peroxide to inhibit evolution of chlorine. The importance of diffusion in the catalytic oxidation of sulfur dioxide was determined experimentally by measuring the rate of oxidation in a flow reactor operated a t various mass velocities, over a platinum catalyst deposited on cylindrical pellets. At high temperatures, low mass velocities, and low conversions ( 7 2 ) the pressure drop between the main gas stream and catalyst surface for sulfur dioxide was as much as 25y0 of partial pressure of the dioxide in the gas stream. .4t low temperatures and high mass velocities the pressure drop is negligible. Research work a t the Tennessee Valley riuthority has shown that platinum and palladium deposit,ed on aluminum metaphosphate or zirconium pyrophosphate are highly active and stable catalysts a t 650" to 800" C. for t,he oxidation of phosphorus with steam to form phosphoric acid and hydrogen ( 4 7 ) . Hydrogen is relatively free of phosphine and phosphorous acid. Supported copper catalysts have high activity and low cost but Suitable conditions for platinum eata\ are relatively less stable. lysts are 650" to 800' C., steam-to-phosphorus vapor-volume ratios of 16 to 30, and space velocities of 640 to 9500 reciprocal hours. In the oxidation of methylcyclohexane by chromyl chloride in carbon tetrachloride solution it has been found t h a t the addition of less than 1% of an olefin initiates a moderately rapid reaction. Similar effects are noted (85) in the case of the oxidation of methylcyclohexane with lead tetraacetate. It has been claimed that mercaptans can be oxidized to sulfonic acids by molecular oxygen in the presence of catalytic proportions of a nitrogen oxide. The higher alkanesulfonies, particularly those containing between 12 and 20 carbon atoms ( 7 6 ) , can be used for the preparation of excellent detergents. Aliphatic sulfonic acids may be prepared from saturated aliphatic hydrocarbons by reaction therewith of sulfur dioxide and oxygen. A plumbic salt of a saturated aliphatic carboxylic acid of 2 to 4 carbon atoms-for example, lead tetraacetate47 wed as catalyst. Other processes for this reaction have proposod tho use of ultraviolet light irradiation for activation (11). The industrial applications of sodium chlorate and chlorine dioxide have been reviewed (6'5). The tremendous importance of submerged fermentation t o t,hc American antibiotics manufacturing industry emphasizc:s the significance of an understanding of the mechanism of oyygen transfer in the process. It has been found that the physical absorption of molecular oxygen is a function only of the design and operating characteristics of the equipment, and the physical properties of the fermentation medium. Quantitative e.;pressions for a series of rate processes have been set up (51). In the case of the submerged fermentation of Strepiorrqres yriseus, the st,eps in the diffusion mechanism include oxygen transfer resistance at bubble and ot,her liquid-air interfaces, a resistance through cell clumps and liquid films around individual cells, and a mechanism which involves direct contact of cells with air bubbles. Experimental results on the effect of air flow and agitation on the rate of growth of Penicillin chrysogenuvn~and Streptomyces griseus have been discussed ( 3 ) in the light of the above hypothesis. Ozone is a powerful oxidizing agent and has found use in water purification, oxidative destruction of phenols in coke oven waste liquors, for textile bleaching in Italy, and experimentally for paper bleaching. The Ozone Process Division of the Welsbach Corp. has published some information on the economics of "toriiiitge ozone." Cost of ozone (45) in large installations is reported to be as low as 10 cents per pound under favorable condition3 and up to 60 cents per pound where conditions are not favoratilc.
INDUSTRIAL AND ENGINEERING CHEMISTRY
1996
The major cost is power, requirements for which are 9 kw.-hr. per pound of ozone when air is used and 4.5 kw.-hr. per pound of ozone with oxygen.
LITERATURE CITED (1) Arthur, J. R., Bangham. D. H., and Crane, H. G., IND. ENG. CHEM.,43,525-8 (1951). (2) Arthur, J. R., and Bowring, J. R., Zbid., 43, 528-33 (1951). (3) Bartholomew, W. H., Karow, E. 0.. Sfat, M. R., and Wilhelrn. R. H.,Zbid., 42,1801-15 (1950). (4) Bateman, L., and Gee, G., T r a m . Faraday Soc., 47, 155-64 (1951). (5) Bates, H. G. C., Evans, M. G., and Uri, N., Nature. 166, 869 (1950). (6) Baxter, S., Morgan, W. McG., and Roebuck, D. S. P., IND. ENG.CHEM., 43,446,452 (1951). (7) Beach. L. K. (to Standard Oil Development Co.), U. S. Patent 2,537,568 (Jan. 9, 1951). (8) Beaven, G. H.; Irving, R., and Thompson, C. N., J. Z n s t . Petroleum, 37,2549 (1951). (9) Blum, G. W., Shelton. J. R.,and Winn, H., IND.ENG.CHEM.. 43,464-71 (1951). (10) Bohmfalk. J. F., Jr., McNamee, R. W., and Barry, R. P., Zbid., 43,78694 (1951). (11) Ihadley, H. W. (to E. I. du Pont de Nemours & Co.), U. S. Patent 2,507,088 (May 9, 1950). (12) Rrokaw, R S., and Pease, R. N., J. A m . Chem. SOC.,72,3237-41 ( I 950). (13) Burgoyne, J. H., and Silk, J. A,, J. Chem. SOC.,1951, 572-84. (14) Can. Chem. ProcessInd., 35 (4),270 (1951). (15) Chzm. A g e (London), 62,775 (May 27,1950). (16) Ibid., p. 813 (June 3,1950). (17) B i d . , p. 851 (June 10, 1950). (14)Zbid.. 63. 291-3, 295 (AUK.26. 1950). Chem. Eny., 56 (8),74 (1649); 57 (4), 183 (1950). Chem. Eng. News, 28,3665 (1950). Ibid., 29, 1252 (1951). Chem. I d s . , 67, 383 (1950). Chem. 2nd. Week, 68, 11 (April 14, 1951). Cines, M. R.. Rubber Age, 69,183-8 (1951). Cook, G. A. (to Linde Air Products Co.), U. S.Patent 2,530,509 (Nov. 21, 1950). Cooper, W. C. (to Pittsburgh Coke & Chem. Co.), ZSid., 2,510,803 (June 6, 1950). Corner, E. 6.. M c h , R. V. J., and Lynch, C. S. (to Standard Oil Development Co.),Zbid., 2,507,502 (May 16, 1950). Cullis, C. F., Bull. SOC. chim. France, Nos. 9-10, 863-8 (Sep tembedctober 1950). Davidson, D. C. (to Shell Development Co.). U. 9. Patent 2,513,994 (July 4, 1950). Dawsey, L. H., Muehlhausser, C. K., and Umhoefer, R. R. (to Buffalo Electro-Chemical Co.),Zbid.,2,537,516 (Jan. 9, 1951); 2,537,655 (Jan. 9, 1951). Deanesly, R. M., and Watkins, C. H., Chem. En@. Progress, 47 (31, 134-40 (1951). Dcnton, W. I. (to Socony-Vacuum Oil Co.), U. S. Patent 2,519,309 (Aug. 15, 1950). Drewitt, J. G. N. (to Celanese Corp. of America), Zbid., 2,530,512 (Nov. 21,1950). Egloff, G., “Techniques et Applications du Petrole,” The Sources of Raw Materials in the Chemical Industry, Part I, pp. 3-8, 1950; Universal Oil Products Co , Library Bull Abstr., XXV (33), 132 (Aug. 16, 1950). Elm, A., Stanley, €1. M., and Tuerck, K. H. W. (to Distillers Co., Ltd.). U. S. Patent 2,514,041 (July 4, 1950). Fasce, E. V. (to Standard Oil Development Co.), Ibid., 2,537,577 (Jan. 9, 1951). Field, E. (to E. I. du Pont de Nemours & Co.), Zbid., 2,504,402 (Aprll 18, 1950). Zbzd.,2,519,751(Aug. 22, 1951). Fisher, G. S., Goldblatt, L. A., Kniel, I., and Snyder, A. D., IND. END.CIIEM..43,671-4 (1951). Carbo, P. W. (to Hydrocarbon Research, Inc.), U. S. Patent 2,526,652 (Oct. 24, 1950). Garner, F. H., Long, R., and Ashforth, G. K., Fuel, 30, 63-6 ( 1 051 ).
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Vol. 43, No. 9
(47) Hein, L. B., Megar, G. H., and Striplin, M. M., Jr., IND.ENO. CHEM..42,1608-22 (1950). (48) Hess, L. G., and Tilton, V. V., Zbid., 42, 1251-8 (1950). (49) Hess, P. S., and O’Hare, G. A., Zbid., 42, 1424-31 (1950). (50) Hess, P. S., and O’Hare, G . A,, Oficial Digest, Federation Paint& Var. Clubs, 144-57 (March 1951). (51) Hixson, A. W., and Gaden, E. L., Jr., IND.ENG. CHEM.,42, 1792-1801 (1950). (52) Hobson, R. W., and D’Ianni, J. D., Zbid.,42, 1572 (1950). (53) Hock, H., Depke, F., and Knauel, G., Chem. Ber.. 83, 238-44 (1950). (54) Hock, H., Lang, S., and Knauel, G., Zbid., 83, 227-37 (1950). (55) Honn, F. J., Bezman, I. I., and Daubert, B. F., J. A m . Oil Chem. SOC., 28, 129-33 (1951). (56) Irving, R., and Thompson, C. N., J. Znst. Petroleum, 37, 67-79 (1951). (57) Johnson, R. (to Koppers Co., Inc.), U. S. Patent 2,507,527 (May 16,1950). ( 5 8 ) Kendall, C. E., IND.ENG. CKEM.,43,452-5 (1951). Oil (59) Koracik, A. P.. and Sachanen. A. N. (to Soconv-Vacuum Co.), U. S. Patent 2,522,678 (Sept. 19; 1950). (60) Langdon, W. K., and Schwoegler, E. J., IND.ENG.CHEM..43, 1011-12 (1951). (61) Lee, D. D.,‘and Sparacino (to E. I. du Pont de Nemours & Co.), U. S. Patent 2,511,475 (June 13, 1950). (62) Lewis, W. K., Gilliland, E. R., and Sweeney, M. P., C h . Eng. Progress. 47, 251-6 (1951). (63) McClellan, P. P., IND. ENG.CHEM.,42, 2402-7 (1950). (64) MacLeod, K. S., Can. Chem. Process I d . ,34, 640-2 (August 1950). (65) McGavack, J., and Bevilacqua, E. M., IND.ENG. CHIDM., 43, 475-9 (1951). (66) McNall, F. M. (to Clark Bros. Co., Inc.), U. S. Patent 2,532,930 (Dec. 5, 1950). (67) Malherbe, F. E., and Wslsh, A. D., Trans. Faraday SOC.,46, 824-35, 835-48 (1950). (68) Meissner, H. P., and Thode, E. F., IND. ENG.CKEM.,43, 129-33 (1951). (69) Mueller, M. B. (to Allied Chemical & Dye Corp.), U. S. Patent 2,513,099 (June 27, 1950). (70) Naples, F. J., and D’Ianni, J. D., IND. ENG.CHEM.,43, 471-5 (1951). (71) Oil, Paint, Drug Reptr., 157,5 (Jan. 8,1950). (72) Olson, R. W.. Schuler, R. W., and Smith, J. M., Chem. Eng. Progress, 46, 614-24 (1950). (73) Payne, W. A. (to E. I. du Pont de Nemours & Co.), U. 8. Patent 2,519,788 (Aug. 22,1950). (74) Pezsaglia, P. (to Shell Development Co.), Ibid., 2,537,553 (Jan. 9, 1951). (75) Polly, 0. L. (to Union Oil Co.), Zbid., 2,533,620 (Dec. 12, 1950). (76) Proell, W. A., and Shoemaker, B. H. (to Standard Oil Co. of Ind.), Zbid., 2,505,910 (May2, 1950). (77) Retaillian, E. R., Richards, H. A,. Jr., and Jones, M. C. K., S.A.E. Journal, Quart. Trans., 4,438-51 (July 1950). (78) Rollman, W. F. (to Standard Oil Development Co.), U. S. Patent 2,526,689 (Oct. 24, 1950). (79) Rust, F. F., and Dickey, F. H. (to Shell Development Co.), Zbid., 2,516,649 (July 25,1950). (80) Schechter, W. H., Miller, R. R., Bovard, R. M., Jackson, C. B., and Pappenheimer, J. R., IND. ENG.CHEM.,42,2348 (1950). (81) ScienceNewsLetter, 58,185 (Sept. 16, 1950). (82) Shelton, J. R., and Cox, W. L., IND. ENO.CHEM.,43, 456 (1951). (83) Simon, D. M., J. Am. Chem. Soc., 73,422-5 (1951). (84) Simonds, J. H. (to Phillips Petroleum Co.), U. 6. Patent 2,530,369 (Nov. 21,1950). (85) Tillotson, A., and Houston, B., J. Am. Chem. SOC.,73, 221-2 (1951). Toland, W, G. (to California Research Corp.), U. S. Patent 2,531,172 (Nov. 21, 1950). Zbid, 2,531,173 (Nov. 21, 1950). Turk, A , , and Boone, P. D., Ibid., 2,530,923 (Nov. 21, 1950). Van Loon, W., and Smeets, H. A,, Fuel, 29, 119-21 (1950). Warner, W. C., apd Shelton, J. R., IND.ENG.CHEM.,43, 11604 (1951). Watson, C. W. (to The Texas Co.), U. S. Patent 2,517,066 (Aug 1, 1950). White, A. G., and Jones. E., J. SOC.Chem. Znd., 69 (7), 2069,209-12 (July 1950). Wicklatz, J. E., and Kennedy, T. J. (to Phillips Petroleum Co.), U. S. Patent 2,511,957(June 20, 1950). Wood, W. S., Holmes, W. R.. and Whittaker, H. (to Laporte Chemicals, Ltd.), Ibid.. 2,520,870 (Aug. - 29, 1950). (95) Yoke, G. R., Fuel,29, 163-7 (1950). (96) Zwicky, F., Chem. Eng. News,28,156-8 (1950). RECEIVED June lQ, 1951.
