mc
OXIDATION L, F. MAREK
ARTHUR D. LITTLE, INC,, CAMBRIDGE, MASS.
T h e oxygen-containing organic compounds comprise a very important segment of organic chemicals manufacture. Some of the largest volume items like methanol, ethyl alcohol, phenol, and other hydroxylated compounds have not characteristically been made b y processes o f direct oxidation of hydrocarbons except as coproducts. Recently, the process involving peroxidation of cumene followed b y a splitting reaction has, however, received considerable commercial attention for manufacture of phenol. Xylenes, now available commercially as individual isomers from petroleum sources, are receiving increased attention as raw materials for oxidation to phthalic acids, both commercially and researchwise. Research continues to be applied to oxidation of methane to synthesis gas, ethylene to ethylene oxide, and other hydrocarbons to various oxygenated organic compounds. Combustion phenomena received considerable attention during the past year at the Diamond Jubilee Meeting in N e w York and at the 119th ACS Meeting in Cleveland. These symposia gave attention to phenomena associated with combustion in engines as well as on grates. The Institute of Petroleum also held a symposium in 1951 devoted to combustion reactions related to gas turbine practice.
A
S HAS been the case with previous reviews of current work
in the field of oxidation, the conversion of hydrocarbons t o useful organic compounds has received a large share of the attention in the research and development work being done in the field. On the whole, this attention has been directed toward improving existing processes and toward a greater fundamental understanding of the processes with a view to subsequent improvement of the industrial application. Research work has continued t o be applied t o various other oxidative processes such as the conversion of already oxidized compounds t o different ones, the deterioration of rubber, the drying of oils, and so on. Work continues t o be directed t o finding out more of the properties and behavior of hydrogen peroxide in connection with its use as the oxidizing agent for certain fuels in specialized uses. Symposia have been presented on the theoretical aspects of combustion and gasification of solid fuels, on combustion chemistry, and on combustion reactions in relation to gas turbine practice. The work represented by the papers at these symposia, while not entirely current, is related t o current work in the several subject areas, and has been summarized and correlated in relation to current interests and theories.
ALIPHATIC HYDROCARBONS The conversion of methane and natural gas t o synthesis gas mixtures of hydrogen and carbon monoxide continues t o receive attention. Some of the results from the development program of Stanolind Oil and Gas Co. on the pilot plant conversion of natural gas t o synthetic liquid fuels have been published (98). Elementary carbon appears in the product when the oxygenmethane ratio is decreased below a critical value. Complete oxygen conversion mas alyays observed. The suggested mechanism consists of primary combustion t o carbon dioxide and water and reformation of methane by this carbon dioxide and water t o carbon monoxide and hydrogen. To avoid the need of generating oxygen gas and permit the use of air without the dilution introduced by the inert nitrogen, the use of intermediate metal oxides as oxygen carriers has been suggested for the conversion of methane to carbon monoxidehydrogen mixtures (130). A fluidized bed technique using finely divided iron or copper oxides has been claimed. Mixtures of such regenerative oxides with petroleum reforming catalysts of nickel on alumina have been claimed to be particularly effective. Oxygen-carrying metal oxide compositions comprised
of mixtures of iron and manganesc oxides (50-50 for example) have likcwise been claimed t o be effective in a fluidized bcd technique for conversion of methane to synthesis gay mixtures (28). The use of regenerative pebble heaters for preheating hydrocarbon and oxygen streams has been dcscribed in connection with formation of acetvlene from low molecular weight hydrocarbons in partial combustion procpeses ( 1 1 4 ) Interest has continued to be strong in processes for conversion of ethylene to ethjlene oxide by direct oxidation procedures. The reactive nature of the compound and its present commercial importance as a.n intermediate for a variety of products ranging from antifreeze t o waxes are reviewed (91). I n efforts t o improve the catalyst effectiveness and life, it has been found that the active silver coating on an inert carrier such as alumina, initially present in extremely finely divided crystallites, gradually loses effectiveness due to the g r o t~h of the crystallites to large size during use of the catalyst. A variety of measures have been suggested to overcome eplis undesirable property of silver catalysts. One of these has been to modify the base support. It is claimed that use of a beryllium oxide support for the active silver results in an extremely ruggedcatalyst having greater life and better heat stability (66). Cambron and coworkers a t the Ottawa, Ontario, laboratories of the Canadian Kational Research Council have developed silver catalysts for ethylene oxidation based on the use of silver alloys with calcium (or other alkaline earth metal) with good claimed results (18). A typical result shows that with 103% calcium alloyed with silver as active catalyst a t a temperature of 264" C., about 60% yields of ethylene oxide based on reacted ethylene are obtained at conversions o n the order of 75% per pass. Catalyst life appears to be good. A fluidized catalyst in ethylene oxidation comprises silvcr deposited on alumina in admixture with a promoter comprising both barium peroxide and an oxide of zinc or copper (113). An example shows a yield of 74% to ethylene oxide a t a conversion of 42% per pass. Inclusion of the vapors of phosphorus or phosphorus-containing compounds in the air-ethylene stream passing over a silver catalyst has been claimed t o result in enhanced yields of ethylene oxide at commercially useful conversion rates (67'). Phosphorus, phosphorous oxides, alkyl esters of phosphoric acid, etc., may be used t o supply the vapors. Further study of the oxidation of olefins hy chromiuni tiloxide in acetic snhydride has shown that all olefins examined are attacked at the double bond but that attack a t the methylene group adjacent to the double bond occurs in some cases and not in others (69). From camphene and dineopentyl ethylene, the corresponding epoxide was the major product Kinetics of liquid phase olefin oxidations have been studied in an effort t o obtain more reliable eatiinates of absolute velocity coefficients and t o study the relative importance of the three termination reactions (11)
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September 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
The burning velocity of ethylene plus air mixtures has been found t o be unaffected by changes in pressure, contrary to some previously reported results (105). No explanation for the differences can be offered with certainty. Celanese Corp. of America continues t o be the largest commercial operator of processes for oxidation of propane and butane to a variety of oxygenated products, with a n operating plant at Bishop, Tex., and additional plants announced for locations in Texas and Canada. Methods for separation and purification of commercial grade products from the oxidation mixture have constituted a major problem t o be overcome. Numerous novel and ingenious methods have been developed. Thus, sodium formate obtained by crystallization from the caustictreated product is claimed t o be decolorized and purified t o a 98%+ purity by washing with a methylal stream, which is finally recycled t o the main product for separation (94). Another example of special processing in this operation is that of quenching t h e hot reaction products with a recycled cooled stream of aqueous formaldehyde, whereby the hot products are cooled below reaction temperature, the formaldehyde is absorbed, and the remaining products are passed t o the next recovery stage (34). Peroxides present in the hot reaction gases are decomposed by passing the gaa stream in contact with packing material, such as carbon steel rings, having catalytic effect on the peroxides. Maintenance of a p H above about 4.0 in the quench liquors reduces the tendency for formation of acetals, formals, and esters by secondary reactions (35). The use of ion exchange resins for the removal of acids from the formaldehyde recovered as a product of the oxidation of propane, butane, etc., has been commercially adapted t o provide a resin-grade product. Various modifications are described from time t o time, such as the separate condensation of formaldehyde together with glycols, acids, color bodies, etc., prior t o other products of the oxidation and as a step in the recovery and purification of the formaldehyde (99). T o increase the conversion prior t o final recovery t o certain products, such as acetaldehyde, in the oxidation of butane, i t has been claimed t o be advantageous t o introduce the oxygen in several stages with intercooling between stages (E%). To obtain data from which t o formulate a scheme of catalytic oxidation from which t o predict results with other hydrocarbons, the vapor phase catalytic oxidation of n-butane, 1-butene, 2-butene, isobutylene, and butadiene was studied over silver and vanadium oxide catalysts (16). The products found from oxidation over vanadium pentoxide catalysts can be explained by a scheme of atomic dehydrogenation and peroxidation followed by decomposition of the peroxide. Conversions of over 50% butadiene t o maleic anhydride were obtained under conditions of complete hydrocarbon disappearance over vanadium pentoxide catalysts. n-Butane was relatively resistant to oxidation under the conditions used for olefins. Oxidation of saturated aliphatic hydrocarbons by air in an aqueous emulsion has been shown t o be catalyzed by substances such aa oxides and salts of manganese, iron, cobalt, copper, and cerium (104). Oxidation of diisopropyl in this way gave a 20.6% yield t o acetone. The elementary free radical reactions occurring in the low temperature oxidation of paraffin hydrocarbons has been studied in the Shell Development Co. laboratories by using various aliphatic peroxides t o provide the free radicals (14). Studies of the low pressure flammability limits of propane-air mixtures gave the classical range when single spark ignition was used but gave a considerably widened range with a train of sparks (33). Alkylation of hydrogen peroxide in aqueous solution-e.g., formation of tert-butyl hydroperoxide-in presence of an acid catalyst is improved by conducting t h e reaction in the presence of a water-immiscible inert organic solvent having a boiling point
2045
below the desired hydroperoxide (15). For example, chloroform may be the inert solvent. I n the liquid phase oxidation of cyclohexane or methyl cyclohexane with air t o form cycloaliphatic alcohols and ketones, it is claimed that the formation of esters is substantially reduced if oxidation occurs in the presence of about 10% added water and the process is terminated at conversions of 15% or less (106). Petroleum Cyclohexane containing sulfur compounds and other hydrocarbons, including small amounts of benzene, may be oxidized t o cyclohexanolcyclohexanone by air in the presence of a cobalt naphthenate catalyst with high yields. In the process the water formed is continuously withdrawn from a refluxcondenser separator (63). Nitric acid oxidation, with 50 to 60% acid of the hydrocarbon-free mixture of cyclohexanol and cyclohexanone in the presence of catalysts of dissolved salts of copper, vanadium, or manganese, results in higher yields of adipic acid than if the oxidation products are first separated (64). A two-stage continuous process is claimed as particularly effective in ensuring high yields of adipic acid. Peroxides may be removed from the oxidation reaction product of cyclohexane by treatment with a n aqueous solution of ferrous, stannous, or chromous salts, a sulfite, or bisulfite (61). I n the case of removing peroxides from synthetic rubber monomers prior to polymerization, peroxides are claimed t o be removed by use of a solution of sodium hydrosulfite, 5 to 20%, containing low concentrations of a dye, such as methylene blue, which acts as a n indicator in the process (27). Finely divided iron with fresh unoxidized surface is effective in removing peroxides from mixtures of hydrocarbons and oxygenated materials (62). Oxidation of relatively high molecular weight hydrocarbons, such as paraffin waxes, can be made to occur at temperatures as low as 100' C. by the addition of minor proportions of chlorine dioxide t o the air stream passing through the liquid hydrocarbon (138). I n one aspect this process is applicable t o the oxidation of microcrystalline waxes. Oxidized microcrystalline waxes (OMC) are now manufactured by at least three companies and are used in the manufacture of emulsified floor polishes (24). It is claimed that separation and purification of the mixture of materials resulting from liquid phase oxidation of hydrocarbons is facilitated by the use of steps involving esterification with a n added alcohol, adding alkali t o saponify groups not in combination with alcohol, separating layers, and fractionating by distillation (134). Mineral acids are suitable catalysts for the esterification step (156). Air oxidation of polypropylene averaging 18 carbon atoms in the chain has been claimed t o result in the formation of novel polyesters of value as plasticizers for vinyl-type resins, rubbery polymers, and various copolymers and interpolymers, and for other use purposes (96). Hydrocarbon-soluble peroxides act as catalysts. Air oxidation of the polymer sludges from a conjunct polymerization reaction is claimed t o result in the formation of oxygen-containing derivatives having modified air-drying properties (100). Oxidation of cis-mono-olefin compounds containing over four carbon atoms may be oxidized to epoxy compounds by means of aliphatic peracids dissolved in the corresponding aliphatic carboxylic acids-e.g., peracetic acid dissolved in acetic acid (49). Examples of the types of olefins applicable here include oleic, ricinoleic, undecylenic, ete., acids, esters of the acids, synthetic monoglycerides, etc. In the autoxidation of cyclopentadiene and of cyclohexadiene, primary peroxide biradicals are formed. These partly stabilize as monomeric peroxides and partly convert to hydroperoxide via polymer chain peroxides broken by oxygen (7s). A study has been reported on the kinetics of cobalt-catalyzed oxidation of trimethylethylene in acetie acid solution (12). A hydroperoxide was found to be the initial product, which forms
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 9
pounds (isopropylbenzene) having a teitiary carbon atom in the alpha position t o the benzene ring, under conditions where potassium permanganate or sodium hydroxide are present in small amounts in the water, leads to the formation of reaction products containing substantial and preponderant amounts of a,ol-di-methylbenzyl alcohol or of 01,01dimethylbenzyl hydroperoxide, depending upon conditions of oxidation (90). Interest continues to exist in processes for the direct conversion of benzene t o phenol by oxidation. It is claimed that by the use of from 1 to 20y0 of hydrocarbon promoters with the benzene being oxidized, the reaction temperature is substantially lowered to on the order of 330" to 350" C. Various nonaromatic hydrocarbons and mixtures are claimed ab promoters (82). Similar claims are made for additions of from 1 to 2074 of di-nalkyl ether containing between two and eight carbon atoms per molecule (83). Per pass conversions of benzene to COURTESY C E L A N E S E CORP. OF AMERICA phenol are quite ]off but the claimell yields are better than 60%. Formaldehyde Processing Equipment and Oxidation Furnaces 4 study of the nonacid products froin the Oxidation of toluene by sodium dichromate and sulfuric acid showed the presence of phenyl an unsaturated aldehyde as a product of the reaction. llechanism is discussed. 0- , m- , and p-tolyl ketones, phenyl 0- , m- , and p-tolymethanes, benzyl alcohol, benzaldehyde, some dibenzyl, and Oxidized in glass apparatus a t 130" C., ethylbenzene reacts with oxygen first to give a very slow radical reaction followed by a traces of diphenylmethane and anthraquinone ( 1). Substantia? amounts of phenol p-tolyl ketone are readily obtained in crystalfaster wall-catalyzed reaction. Both reactions produce only hydroperoxide product (68). line form. Interest continues in the air oxidat'ion of xylenes and other substituted benzenes to useful products. Thus, with vanadium AROMATIC HYDROCARBONS pentoxide catalysts the presence of small amounts of sulfur dioxide gas has been found t o be helpful in the selective oxidation Fui the1 information has been published about the culnene of the ortho aliphatic-substituted benzenes to phthalic anhydride hydioperoxide process foI phenol and acetone manufacture and and the sharply &electiveoveroxidation of the meta- and parathe commercial plans of companies involved (21, 25). -4desubstituted benzenes present in the mixture to the point of ring scription of the process and a flow sheet of the commercial operarupture. Thus, feed xylene niixt.ures containing TO to 95y0 tion starts with benzene and propylene and carries the process ortho and substantial amounts of meta and para isomers are by steps t o the phenol plus acetone product (102). Using oxidized t o phthalic anhydride lyith carbon dioxide and water benzene from the new United States Steel Corp. plant, Hercules is as waste products (12.4). Such use of sulfur dioxide with vanareported t o be planning for annual production of 15,000,000 dium pzntoxide catalysts in the commercial oxidation of o-xylene pounds of phenol, 12,000,000pounds of actone, 5,000,000 pounds to phthalic anhydride not only permits smoother operation with of pcresol, and 5,000,000 pounds cymene alcohol (ore floatation fewer hot spots in the catalysts but also permits an increase in reagent) by this process in a New Jersey plant. throughput'of 8 to 12y0( 1 2 3 ) . Treatment of p-cymene (p-methylisopropylbenzene) by thp Liquid phase oxidation of p-xylene t.0 terephthalic acid with peroxidation-decomposition process yields p-cresol and acetone. molecular oxygen in the presence of catalysts like the oxides of Starting with diisopropylbenzene, either the mono- or dihydrocobalt, vanadium, chromium, copper, nickel, and the like is peroxide may be obtained and from these, a variety of products improved by the presence of cert,ain free-radical generating subincluding isopropylphenol, isopropyl acetophenone, hydrost,anceslike hexachloroethane (45). Ot'her free-radical generating quinone, diacetylbenzene, and others, depending upon the desubstances such as tetraethyllead are also effective in this proccomposition technique. ess ( 7 2 ) . Oxidation to the hydroperoxide of the alkylbenzene (one or In the oxidation of dialkylbenxeiies with air to mono- or dimore alkyl groups a t least one of whlch has a tertiary carbon atom basic acids, the yields are improved when the catalyzed reaction in the alpha position to the benzene ring) is claimed to be best mixture contains small proportions of s a h of enolized dilretones performed with molecular oxygen vihen the hydrocarbon is emulsified in water using emulsifying agents such as soaps or ( 4 2 ) . Metals such as cobalt, lead, iron, nickel, copper, and manganese are suitable. synthetic agents. Thus, from 200 ml. of isopropylbenzene Oxidation of mixtures of nz- and p-xylenes can be made t o there is obtained after 14 hours a product containing 69.4 grams give mixtures of isophthalic and terephthalic acids which may of isopropylbenzene hydroperoxide (62). be subsequently separated by a process of noncatalytic selective To overcome irregularities in results from use of commercial wterification ( 3 ) . Isophthalic acid esterifies with an alcohol cumene in production of cumene hydroperoxide, the use of finely without a catalyst, whereas terephthalic acid requires catalytic divideS sodium bicarbonate suspended in the cumene is claimed esterification. (84). Tetracarboxylic acid anhydrides, such as pyroniellitic anhy,4ir oxidation of emulsions of alkj-I-quhstituted aromatic coni-
September 1952
INDUSTRIAL A N D ENGINEERING CHEMISTRY
dride may be obtained by the air oxidation of aromatic hydrocarbons having two pairs of ortho-positioned alkyl groups, such as durene, with catalysts such as vanadium pentoxide (97). Alkyl-substituted benzenes having a tertiary alkyl group and at least one nontertiary alkyl group directly substituted on the benzene ring can be selectively oxidized with molecular oxygen in the presence of suitable oxidation catalysts to produce high yields of aromatic carboxylic acids having a tertiary alkyl group on the benzene ring. Preferred catalysts are compounds of heavy metals having atomic weights in the range of 50 to 190 (66). Air oxidation of ethylbenzene in liquid phase with catalysts such as manganese acetate can be made to produce high yields of acetophenone and low yields of benzoic acid. By initial addition of acetic anhydride, preponderant yields of (a-hydroxyethy1)benzene result under otherwise comparable conditions (6). Toluic acid from the catalytic partial oxidation of p-xylene may be oxidized with molecular oxygen in water solution as the alkali metal salt to substantial (over 60%) yields of terephthalic acid (44). Benzyl ether, by-product of benzyl alcohol manufacture, may be air oxidized largely to benzaldehyde, benzoic acid, and benzyl benzoate at temperatures in the range of 160" to 300" C. (40). Dibutyl phthalate has been claimed to be a selective absorbent for phthalic anhydride and maleic anhydride vapors from reaction gas mixtures. Whereas maleic anhydride is soluble at temperatures of from 10' to 50" C., phthalic anhydride does not become significantly soluble until a range of 60' to 125' C. is reached (87). Aromatic hydrocarbon mixtures boiling between 165' and 185' C . and obtained from petroleum cracking operations may be oxidized with air over the usual vanadium pentoxide catalysts t o yield phthalic anhydride (IS). Other aromatic hydrocarbons, such as phenanthrene, oxidized t o phthalic anhydride as the major product, phenanthrene giving a yield of 55% over sodiumvanadium pentoxide microspheres in a fluidized bed (2.9). Tetrahydronaphthalene peroxide, useful as a n ignition accelerator in Diesel fuels, may be obtained from tetrahydronaphthalene (Tetralin) by air oxidation in the presence of cupric carbonate catalyst. The peroxide may be recovered as a sodium salt precipitated from the reaction mixture (SO). The reaction of benzoyl peroxide with a-chloro, a-bromo, and a-nitronaphthalene has been investigated (SO) to determine the relative activating influence toward benzoyloxy free-radical attack, as follows: NO2 19 > Br 2.0 > C1 1.2 > H 1.0. When phenols react with benzoyl peroxide in hot chloroform solution, the distinctive reaction is the introduction of a benzoa t e group into the aromatic nucleus in a n ortho position to the hydroxyl group (99).
CARBON AND SOLID FUELS Papers presented at the Symposium on Theoretical Aspects of Combustion and Gasification a t the Diamond Jubilee Meeting of the AMERICAN CHEMICAL SOCIETY and so far published will be briefly considered here. To gain further information on the chemical reactions which occur in the combustion of fuels in beds, the British Coal Utilisation Research Association made studies of the combustion of charcoal and graphite (4). Single particles were reacted with air in the range 800' to 1000' C. at pressures varied downward from atmospheric. Particular attention was paid to conditions at which a blue glow was observable around the carbon particle. Using artificial graphite, workers at the Westinghouse research laboratories made a systematic study of the reactions with oxygen and with carbon monoxide under a variety of conditions ( 6 0 ) . The paper compares theoretical rate expressions for graph-
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ite oxidation with experimental rates of reaction, The ratecontrolling processes in this case are shown to be immobile adsorption with dissociation and mobile adsorption. The fundamental postulates of the activated state theory of chemical reactions on surfaces are discussed. The effect of high temperature pretreatment on the reactivity of low temperature char to steam and carbon dioxide has been reported from the laboratory of Pittsburgh Consolidation Coal Co. (58). Study was also made of the effect of pressure and carbon burnoff on the rate of reaction of low temperature char with steam-hydrogen mixtures at 1600" F. The fluidized-bed technique was used for the experimental work. Bureau of Mines studies of the catalytic reverse shift reaction have been made to evaluate the possible applicability in the adjustment of hydrogen-carbon monoxide ratios of synthesis gas mixtures ( 7 ) . The constants in the rate equation were evaluated a t 1000' F. and a probable mechanism for the reaction was postulated. Economics of the scheme dep,end upon the relative advantages t o be gained by employing the necessary large excesses of steam in the carbon-gasification step. Use of elevated pressures in the range of 20 to 30 atmospheres in the gasification of solid fuels offers advantages of high equipment capacities and high fuel rates, low oxygen requirements, and labor economy (61). Results of work at Battelle Memorial Institute have been compared with calculated effects, Results from the experiments of the Bureau of Mines on the gasification of coal with oxygen and steam in a vortex-type reactor have shown the practical possibilities for this procedure (41). The experimental unit was operated under slagging conditions without difficulty. The experimental unit itself has resulted from a substantial program of development work and is the outcome of application of both theoretical consideration and practical experience. While not a part of the symposium mentioned above, a discussion of powdered coal gasification from the Bureau of Mines is a part of the same problem and shows the effect of variables on the process ( 1 1 7 ) . Results from the large and small pilot plants at Morgantown, W. Va., form the basis of this discussion. T h e basis for choice of coal to be used is discussed. A design has been patented of a means for gasifying powdered coal to produce synthesis gas. The design is based on a vertical cylindrical vortex-type reactor which is claimed to give high carbon conversion and no slagging problems (56). By adjusting the ratio of oxygen t o steam, i t is possible to produce gas with little or no carbon dioxide. Tonnage oxygen has apparently reached a stage of development where consideration is more frequently directed to the commercial aspects rather than the technical problems involved. A review has recently appeared in which the various commercial factors of plant, capital, production, use aspects, and so on are presented (30). -4nickel subsulfide catalyst operating in a temperature range of 220" t o 370" C. has been found effective for lowering the sulfur content of coal gas by a process of oxidation of the organic sulfur compounds present (59). A plant treating 1,500,000 cubic feet per day of coal gas has been a t work for 14 years in England and plans for much larger equipment have been made. A theory, developed for calculating the combustion rates of liquid fuels and now applied to the combustion of solid particles, postulates a n analogy between combustion and heat transfer processes (129). Combustion rates are predicted from heat transfer coefficients. The oxidation of coal by nitric acid to form organic acids of the benzenoid or aromatic type is claimed to be improveJ, in that less nitric acid is required, by performing the reaction under a re]% tively high oxygen pressure ( 7 4 ) . Under these conditions, the nitric oxide formed from the reaction ip regenerated by action of the oxygen to reform nitric acid.
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INDUSTRIAL AND ENGINEERING CHEMISTRY COMBUSTION
Papers from the Symposium on Combustion Chemistry presented a t the 119th Meeting of the ANERICAN CHEMICAL SOCIETY in Cleveland, Ohio, have recently been published. Some of these are referred to herein. It is of interest to quote from the introductory remarks (120) to the symposium: "Because combustion is such a complex process, and because it involves homogeneous and heterogeneous types, a great variety of interesting phenomena are observed and it would appear to be possible to do great amounts of research without contributing appreciably to the solution of a given practical problem. I t would, therefore, seem that more immediately useful results may be obtained by basing a good proportion of research studies on phenomena that are observed in actual equipment of interest. "Recent fundamental work on ignition energy and the mechanism of quenching have done much to contribute to a quantitative understanding of the relationship between these phenomena, and is a good example of the way in which basic research on a simple and moderately well-understood system can be applied to more complex practical systems." Reactions of major importance may occur during the compression stroke prior to spark ignition in operating spark ignition engines. Cracking and dehydrogenation of the hydrocarbons in the fuel, polymerization of oxidation products, and formation of various oxygenated compounds are the usual reactions observed (110). Thus, a t the time of ignition the fuel may be significantly different from that fed t o the carburetor. These prereactions vary with fuel type, engine design, and operating conditions. Proper correlation of these factors are needed for optimum operation. Studies have shown that: ( 1) Heat liberated during precombustion reactions may amount to 10% of the total heat of combustion of the fuel ( 2 ) Presence of tetraethyllead does not affect the rate of heat liberation during precombustion but is effective in delaying the onset of autoignition. (3) Increase in octane number lowers the heat released during precombustion. (4) Substantial poi3 er increase results from the presence of precombustion reactions in an engine operated a t delayed ignition (111,127).
Compression-ignition of homogeneous fuel-air mixtures was studied using n-heptane and n-hexane as fuels (88). Both of these fuels exhibit a pronounced two-stage autoignition reaction over a wide range of operating conditions. No ionization was observed during the first-stage reaction but considerable ionization occurred in the engine cylinder during firing. In autoignition by rapid compression, the addition of tetraethyllead always increases the duration of the second stage with n-heptane as fuel (89). Tetraethyllead may increase, decrease, or have no effect on the first stage of n-heptane autoignition, depending on conditions of temperature and pressure. In studies directed to an interpretation of how the antiknock agents, tetraethyllead iron carbonyl, etc., act in an engine, the effects of these materials on the decomposition of hydrogen peroxide, ethyl hydrogen perouide, and diethyl peroxide were determined (99). The results cleaili showed that the action is catalytic and very dependent on the nature of mrtal but not on particle iize. Properties of a series of peroxides, likely to p1a-y a role in the engine knock phenomenon, have been reported an aid to further studies and better identification of peroxides n-hich occur in combustion processes (38). Intermediate aldehydes have been proposed as the most generally important branching agents of a chain process in hydrocarbon combustion (101). By means of an ultraviolet light-absorbing technique applied t o the preflame combustion products of hydrocarbons, p-dicarbonyl compounds were identified as possibly important
Vol. 44, No. 9
intermediates in the preflame oxidation reaction (8, 9, 1 2 2 ) . From n-butane the compound was butanol-Sone and from npentane it was 2,4pentanedione. The Institute of Petroleum held a Symposium on Combustion Reactions in Relation t o Gas Turbine Practice in early 1961, the papers from which have recently been published. Some of these will be mentioned herein. Some considerations on the combustion aspect of gas turbine design and operations have been presented (32). The most pressing need is stated t o be further work on the aerodynamics of combustion chambers to give more information on the air-flow patterns required for flame stability. With respect to fuels the main need is a n extension of the work on factors affecting reaction rate, ignition lag, and behavior of fuel sprays as well as single droplets. The main advances, however, are t o be looked for from the combustion chamber designer rather than the fuel technologist. The evaporation and combustion of falling droplets of liquid fuels, including pure hydrocarbons, commercial distillates, and residual fuels, have been studied experimentally in the National Gas Turbine Establishment, Ministry of Supply, England (126). It was concluded that less advantage will be obtained by securing fine atomization than is t o be expected from simple theory, largely because the conduction of heat to the interior of the droplet reduces the heat available for the evaporation of the smaller droplets. Because of dominant economic position of coal and despite its several technical shortcomings as a fuel for turbines, considerable attention has been given t o t h e development of the coal-fired gas turbine in England (77), the United States, and elsewhere. It was believed t h a t on the basis of information already developed and the continuation of development, it was reasonable t o expect that the construction of practical coal-fired gas turbines would not be delayed because of problems related to combustionchamber design. Additives of the metal oxide type have found application in fuel oils to improve combustion and reduce soot formation (126). To indicate the effect of molecular structure on flame velocity, flame velocities of a series of alkadienes and cycloalkanes were measured (57). Maximum flame velocity is reached usually a t hydrocarbon concentrations somewhat greater than stoichiometric. The effect of unsaturation of the hydrocarbon on flame velocity decrease with increase in molecular weight. Methyl substitution reduces flame velocity, the initial effect being more pronounced than subsequent methyl additions. Oxidation of n-hexane at precool-flame temperatures (276' to 280' C.) has been shown t o give rise t o formation of relatively stable organic peroxides with little hydrogen peroxide (86). Cool-flame oxidation (300' to 400" C.) on the other hand formed primarily unstable mixtures of hydrogen peroxide and formaldehyde. Oxidation of isomeric hexanes, 2,3-dimethylbutane and 2,2-dimethylbutane, a t 480" C. was found t o be slight with formation of hydrogen peroxide, formaldehyde, water, and olefins. This latter characteristic has been pointed out by Hinshelwood ( 7 1 ) in a summary of the effect of structure and substitution of hydrocarbons on oxidation, as follows: 1. Oxidation rate is substantially lowered by introduction of extra methyl groups. 2. Oxidation rate is greatly reduced where the only place for attack is a methyl group. 3. Presence of chlorine, carbonyl, or amino groups in the molecule increases oxidation rate. 4. Ethers are much more easily oxidized than paraffin hydrocarbons. 5. I n general, the oxidation rate increases with increase in chain length. The presence of diluent hydrogen has been found to have a specific inhibiting effect on the oxidation of hexane (118), probably because of the efficiency of energy transfer collisions in deactivating active peroxides.
September 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
I n the low-temperature oxidation of n-heptane, two distinct peaks have been found in the temperature-peroxide curve at 340' and 390" C., with possibly a small peak a t 440' C. (46). The inhibiting effects of surfaces of gold, nickel, and stainless steel were studied. Under other conditions, it has been found that the low-temperature oxidation range of n-heptane was about 250' t o 400" C. and of methycyclohexane, about 325' to 400" C. (53) Aldehydes and ketones of relatively high molecular weight plus some carboxylic acids and formaldehyde were formed by the oxidation. Slow oxidation of n-heptane in the temperature range of 305' to 480' C. has been shown to result in the formation of complex mixtures of aldehydes, ketones, and acids, with formic and acetic acids predominating (107). Comparison of the vapor phase oxidation of methylcyclohexane and toluene over the range from 300" to 500' C. has shown the formation of unsaturated hydrocarbons in the products from the cycloparaffin but not from toluene (&). Isooctane was only slightly oxidized below 500' C. I n the case of n-heptane, peroxides begin t o appear as oxidation products at 250" C. and increase rapidly t o a maximum between 275' and 300" C., at which temperatures other oxidation products appear in quantity (66). Oxidation of methylcyclohexane commences so abruptly t h a t no determination could be made of the temperature, if any, a t which only peroxides appear. Elevated temperature flammability limits in air for n-hexane, n-heptane, n-octane, iso-octane, 72-nonane, n-decane, and kerosene have been determined in a new apparatus by the U. S. Bureau of Mines (188). The data indicate an average decrease of 8% in the lower limits for a corresponding increase of 100" c. The kinetic aspects of the combustion process are of particular interest in the case of the ram-jet burner since the time of residence of the fuel air mixture is so short. An effort has been made to relate flame temperature at the lean flammability limit to the activation energy of the rate-determining reaction in a flame front (4'7'). A correlation was obtained between minimum spark ignition energies and lean limit flame temperatures. The combustion characteristics of Diesel fuels were studied on the basis of the ignition-lag phenomena (78). Bomb tests as well as engine reeults show that hydrocarbon structure is of primary importance in determining combustion characteristics of fuels. Tests on ignition lag sensitivity t o change in cetane number indicate t h a t only very small differences are shown between fuels of 44, 48, and 52 cetane number but that there are appreciable differences in ignition delay for fuels below 44 cetane number. Nitro alkanes, nitrates, nitro carbonates, and peroxides were the types of Diesel fuel additives studied over a period of years at the U. S. Naval Engineering Experiment Station. The performance and stability of some of these Diesel fuel ignition quality improvers have been reported (112). Fuel properties other than ignition quality are also affected by these additives and are considered in this paper. The Bunsen flame continues t o be of interest as a means for studying the phenomenon of combustion ( I ? , 129). Studies are being made of the effects of fuel-air ratios, pressure, and temperature on the burning velocity of laminar flames, temperatures attained in the flames, and the nature and concentrations of free radicals t h a t play important roles in the reactions. The Combustion characteristics of mixtures of methane and propane were studied in a compression-ignition engine (Diesel cycle) (sa). It was found that these fuels react during compression and that the prereactions considerably influence the subsequent combustion of the injected liquid fuel. Spontaneous ignition temperatures for 94 pure hydrocarbons and 15 commercial fluids are reported from the laboratories of the National Advisory Committee for Aeronautics (79). These data are self-consistent and eliminate the inconsistencies in compilations from a variety of publications. The information
2049
COURTESY OELANESE CORP. OF AMERICA
V i e w inside Formaldehyde Plant Showing Reaction and Processing Equipment
should be of value in studies of combustion and of fire hazard evaluations. A study of the flammability limits of pure hydrocarbon-air mixtures has been made at reduced pressures and room temperature (36). A total of 17 hydrocarbons was used, ranging from methane to 2-methylpentane and including five olefins.
MISCELLANEOUS
*
The prior a r t for converting alcohols t o acids has been largely based on the two-step process of first converting the alcohol t o aldehyde (ethyl alcohol to acetaldehyde) and then converting the aldehyde t o acid. The first step is chemically a dehydrogenation and may be so performed or an oxidation process may be used (26). More recently, it has been shown t h a t ethyl alcohol may be directly oxidized t o acetic acid in liquid phase processes employing dissolved catalysts and air for oxidation. Acetaldehyde-activated cobalt acetate in glacial acetic acid solution is claimed to permit yields of %yobased on ethyl alcohol feed (76). Fresh alcohol feed is first mixed with at least one third the equivalent of aldehyde before being introduced t o the reaction zone. Combination of chromium cobalt acetate with acetate in a process such as above is claimed to increase the yield still more t o as high as %'yo(76). The slow oxidation of various ethers by oxygen in a vapor phase reaction has been studied (37). All of the ethers studied were found to be generally similar in the kinetics of slow oxidation. Formic acid is claimed as a uni ue solvent in the liquid phase oxidation of acetals t o acids by maecular oxygen (93). A cobalt acetate catalyst is effective. Examples are shown where high product yields are obtained with formic acid solvent under conditions where no reaction occurred with toluene or acetic acid solvent. Condensation of furfural with butadiene and water results in the formation of a lactone which may be obtained as a by-product of the separation of butadiene from butenes with a furfural solvent. This lactone may be hydrogenated under pressure and the resulting product oxidized with nitric acid t o form adipic acid (70). Monobasic, saturated fatty acid mixtures having from 2 t o 20 carbon atoms per molecule are claimed to result from the air oxidation of mixtures of oxygenate and olefinic compounds obtained from Fischer-Tropsch or oxo-aldehyde processes ( 4 6 ) . Catalysts consisting of salts or soaps of manganese, copper, cobalt, and the like may be used. Results are presented and certain conclusions drawn from studies of oxygen absorption,. peroxide accumulation, and ultraviolet spectral changes during the autoxidation of various esters
2050
I N DtU S T R I A L A N D E N G I N E E R I N G C H E M IS T R Y
Vol. 44, No. 9
of pure unsaturated fatty acids ( 2 6 ) . Conclusions are to be like aluminum metal at 150" C. temperatures. The explosive published. mechanism involves straight chains only, essentially thermal The chemical stability of the organic oxidation products from in nature. reaction of peanut oil with oxygen is claimed to be increased by conducting such oxidation in the presence of an enzymatic exSome of the less well known processes for hydrogen peroxide tract previously prepared from the same raw material (109). formation have been reviewed (19). Oleic acid is claimed to be air oxidized to mixtures of 9,lOSome of the practical shortcomings of the cupric chloride dihydroxystearic, pelargonic, and azelaic acids (121). The usual catalysts which are effective in the Deacon process for the oxidaoxidation catalysts, such as cobalt or manganese salts, are claimed to he effective. Temperatures ranging from 50" to tion of hydrogen chloride t o chlorine are overcome by use of the 100" C. are preferred. fluidized bed principle (31). By supporting the cupric chloride The rate of oxygen absorption of both GR-S and Hevea polyon inert granular carrier material and feeding cupric chloride mers is affected bv the nature of the electrolvte used t o coamlate continuously t o replace that vaporized, it is possible to maintain t,he latex (108). 'Hevea vulcanizates absor6 oxygen much-more rapidly than those from GR-S and only one fourth as much a n active catalyst bed for as long a period as desired. oxygen is needed t o reduce t'he tensile as much as 50%. I n genilbsolute rate constants for olefinic oxidations have been detereral, the presence of copper, cobalt, and iron promotes oxidation. mined by measurement of photochemical pre- and after-effects A new method for oxidation of cholic acid to 3a,l2a-dihya t low oxygen concentrations (10). Termination reactors indroxy-7-ketocholanic acid in much higher yields than previously obtainable consists in the use of a cyclic N-halo-imide, such as volving peroxide radicals only become negligible a t pressures so A7-bromo and N-chloro derivatives of imides of aliphatic and low that diffusion is completely rate controlling under the condiaromatic dicarboxylic acids (l\7-broniosuccinimide) (48). Other tions of experiment. advantages claimed are the noncritical nature of solvents which I n a study of the pre-ignition reactions of some combustible m a r be used and the noncritical concentrations of oxidizing agent. &so, the 3-hydroxy grouping in 416-3,21-dihydroxy-ll-keto- substances with solid oxidants, potassium chlorate, perchlorate, 20-cyanopregnene can be selectively oxidized to a 3-keto radical and nitrate were reacted with carbon black, paraffin wax, starch, wit,hout affecting the hydroxyl in the 21 position by means of an and asphalt (109). osidizing agent from the class consisting of N-bromosuccinimide Autoxidation of saturated paraffin hydrocarbons ranging from and S-bromoacetamide ( 8 1 ) . Methanol is the preferred solvent,. Bauxite is claimed as a catalyst for the oxidation of mercaptans 8 to 22 carbon atoms in the liquid phase was investigated t o in petroleum products to sulfides by means of air (95). Aluminadetermine the relation of structure to rate of oxidation and to base catalysts of chromia, vanadia, and magnetic iron are particucollect data on rate of oxidation (132). Hydroperoxides were larly suit,able. detected in the first stage of reaction. In most of the experiHydrazine (N2Hd) undergoes autoxidation with the interments, cobalt stearate was used as the catalyst to obtain measurmediate formation of peroxide and eventual decomposition to able reaction rates a t temperatures below the hydrocarbon boilnitrogen and water. The reaction is markedly catalyzed by iiig points. dissolved copper (6). Stabilizers include sulfides, thiocyanates, potassium ethyl xanthate, p-lert-butylcatechol, and sodium LITERATURE CITED diethyl thionophosphate. I t is recommended that an effective Abell, R. D., J . Chem. Soc., 1951,1379W31. stabilizer be added to hydrazine to overcome the catalytic effect3 Abere, J.. Mark, H., and Hohenstein, W.P., J . AppZied Chem ., of copper which may be introduced during manufacture, storage, 1, 363-70 (1951). or shipment. -Xgnew, R. J., and Canary, R. E. (to The Texas Co.), U. S. Patent 2,569,440 (Oct. 2, 1951). It has been found that molecular oxygen may be used in the Arthur, J. R., and Bleach, 3. A , Ibid., 44, 1028-34 (1952). presence of lime to produce vanillin in satisfactory yields from hudrieth, L. F., and Mohr, P. €I., 1x0. ENG.CHEW.43, 1774-9 lignosulfonate materials obtained as by-products from the sulfite (1951). process of paper manufacture (50). Oxygen partial pressures Baker, G . A., and Hunter, William (to Celanese Corp. of America), U. 8 . Patent 2,545,870 (March 20, 1951). are held to less than 20 pounds per square inch a t temperatures Barkley, L. W., Corrigan, T. E., Wainwright, H. W., and Sands, in the range of 120' t o 200' C. to avoid overoxidation. A. E., IKD.ESG.CHEM.,44, 1066-71 (1952). From the literature, it is t,o be learned that the presence of Payne, J. Q . , and Thomaj, Barusch, &I. R., Crandall, H. K., oxygen may be the came of both an increase as well as a decrease J. R., Ibid.,43, 2764-6 (1951). Barusch, M. R., Neu, J. T., Payne, J. Q., and Thomas, J. R., in the over-all rate of polymerization reactions. Results have been Ibid.,43, 2766-9 (1951). reported from a quantitative st,udy of the relation between Bateman, L., Bolland, J. L., and Gee, G., T r a n s . FaradaU amount of oxygen initially present and the length of induction SOC., 47,274-85 (1951). period (2). It was found that the initial oxygen pressure is Bateman, L., Gee, G., SZorris, -4.L., and Watson, M-.F., Discussions Faraday Soc., 1951,N o . 10,250-9. closely related to the amount of peroxides formed during the inBawn, C. E. H., Pennington, A. h.,and Tipper, C. F. H., Ibid., duction period. These peroxides cause a normal free radical1951. No. 10.282-91. catalyzed polymerization reaction and bimolecular termination. Beach, L. K. (to Standard Oil Development C o . ) , U. 9. Patent The preparation of "blown" drying or semidrying oils is claimed 2,581,068 (Jan. 1, 1952). t o be advantageously affected when ketene or diketene is fed Bell, E. R., Raley, J. H., Rust, F. F., Senbold, F. H.. and Vaughan, W.E., Dzacusssons Faraday Soc., 1951, iYo 10, t o the oil being blown, in addition to the oxygen-containing gas 242-9 normally used (86). The useful temperature for blowing is Bell, E. R., Rust, F. F., and T'aughan, W~ E. (to Shell Developlowered to a point such that discoloration of the oil, normally ment Co.), U. 8. Patent 2,573,947 (Kov. 6, 1951). encountered, is avoided and a light-colored product is obtained. Brctton, R. H., Wan, Shen-Tu, and Dodze, B. F., IKD.EXG. Insoluble, infusible organo-silicon resins may be obtained by CHEM.,43,594-603 (1951). Caldwell, F. R., Broida, H . E'., and Dover, J. J., Ibid.,4 3 , 2731baking a t temperatures in the range of 120' to 150' C. a soluble 9 (1951). organo-silicon polymer to which a peroxide catalyst has been Cambron, Adrien, and SlcKim, F. L. W. (to Honorary A4drisadded (116). Peroxides similar t o those in commercial use for ory Council for Sei. and Ind. Research), C. S . Patent 2,562,the catalyzing of pure organic polymerization reactions are effec857 (July 31, 1931); (to National Research Council), C . S. Patent 2,562,858 (July 31, 1951). tive with the silicon polymers. Chem. &e. 62,355-7 (Sept. 15, 1951). Vapors containing 26 mole % or more hydrogen peroxide can Chem. Eng., 58, 186-8 (July 1951). he exploded a t atmospheric pressure by ignition with a hot wire Ckem. Week, 69, 11 (June 23, 1951). or spark (116). At 200 mm. total pressure the limit is 33 mole % [ b i d , , 69, 20 (Aug. 25, 1951). and at 40 mm. total pressure i t is 55 mole yo. Vapors in the Ibid., 70, 14 (Feb. 2, 1952). I b i d . , 70, 45 (March 8, 1952). explosive limits at 1 atmosphere may be exploded by catalytically Chipault, J. R . , Kickell, E. C., and Lundberg, W.O., O f i c i d active materials initially a t room temperature or by materials I
-
INDUSTRIAL AND ENGINEERING CHEMISTRY
September 1952
Digest Federation P a i n t & Varnish Production Clubs, 322, 740-50 (November 1951). (26) Church, J. M., and Joshi, H. K., IND.ENG. CHEM.,43, 180411 (1951). (27) Cohen, C. A. (to Standard Oil Development Co.), U. S. Patent 2,565,354 (Aug. 21, 1951). (28) Corner, E. S., and Lynch, C. S.(to Standard Oil Development Co.), Ibid., 2,553,551 (May 22, 1951). (29) Cosgrove, S. L., and Waters, IT. A., J . Chem. SOC.,1951, 1726-30. (30) Dannley, R. L., and Gippin, Morris, J . Am. Chem. Soc., 7?, 332-4 (1952). (31) Davis, C. W., Ehlers, F. A., and Ellis, R. G. (to The Dow Chemical Co.), U. S.Patent 2,547,928 (April 10, 1951). (32) Dawson, J. G., J . Inst. Petroleum, 37, 509-16 (1951). (33) Delbourgo, R., and Laffitte, P., Nature, 167, 985-6 (June 16, 1951). (34) Dice, H. K. (to Celanese Corp. of America), U. S.Patent 2,570,215 (Oct. 9, 1951). (35) Dice, H. K., and Mitchell, R. L. (to Celanese Corp. of America), Ibid., 2,570,216and 2,570,217 (Oct. 9, 1951). ( 3 6 ) Di Piazza, J. T., and Gerstein, M., IND.ENG.CHEM.,43, 27215 (1951). (37) Eastwood, T. A., and Hinshelwood, Sir Cyril, J . Chem. SOC., 1952,733-8. (38) Egerton, A. C., Emte, W., and Minkoff, G. J., Discussions Faraday SOC.,1951, KO.10, 278-82. (39) Egerton, A. C., and Jain, B. D., Fuel, 31,62-74 (1952). (40) Eichel, F. G. (to The Givaudan Corp.), U. S.Patent 2,561,350 (July 24, 1951). (41) Elliott, M. A., Perry, H., Jonakin, J., Corey. R. C., and Khullar, M. L., IND. EXG.CHEM.,44, 1074-82 (1952). (42) Emerson, W. S., and Heimsch, R. A. (to Monsanto Chemical Co.), U. S.Patent 2,552,267 (May 8, 1951). (43) Ibid., 2,552,268 (May 8, 1951). (44) Emerson, W. S., Shafer, T. C., and Heimsoh, R. A. (to Monsanto Chemical Co.), Ibid., 2,559,147 (July 3, 1951). (45) Fallah, A., Long, R., and Garner, F. H., Fuel, 31, 4-18 (1952). (46) Fasce, E. V. (to Standard Oil Development Co.), U. S. Patent 2,553,364 (May 15, 1951). (47) Fenn, J. B., IND. ENG.CHEM.,43,2865-9 (1951). (48) Fieser, L. F. (to Research Corp.), and Rajagopalan, S. (to united States of America), U. S. Patent 2,569,300 (Sept. 25, 1951). (49) Findley, T. W., and Swern, D. (to United States of America), Ibid., 2,567,930 (Sept. 18, 1951). (50) Fisher, J. H., and Marshall, H. B. (to The Ontario Paper Co., Ltd.),Ibid., 2,576,752 (Nov. 27, 1951). (51) Fleming, H. W. (to Phillips Petroleum Co.), Ibid., 2,552,670 (May 15,1951). (52) Fuqua, M. C., and Garrett, B. S. (to Standard Oil Developnient Co.), Ibid., 2,563,598 (Aug. 7, 1951). (53) Garner, F. H., and Petty, D. S., Trans. Faradag SOC.,47,877-84 (1951). (54) Ibid., pp. 884-9. (55) Ibid., pp. 889-96.. (56) Gaucher, L. P. (to The Texas CO.), U. S. Patent 2,558,746 (July 3,1951). (57) Gerstein, M., Levine, Oscar, and Wong, E. L., IND.ENG. CHEM.,43,2770-2 (1951). (58) Goring, G. E., Curran, G. P., Tarbox, R. p., and Gorin, Everett, Ibid., 44,1051-65 (1952). (59) Griffeth, R. H., Ibid., 44, 1011-14 (1952). (60) Gulbransen, E. and Andrew? K * F.? Ibid*, 44? 1034-51 (1952). (61) Gums, W., Ibid., 44, 1071-4 (1952). (62) Hall, R. H., and Quin, D. C. (to Hercules Powder Co.), U. 9. Patent 2,547,938 (April 10, 1951). (63) Hamblet, C. H., and Chance, F. S. (to E. I. du Pont de Nemours & Co., Inc.), Ibid., 2,557,281 (June 19, 1951). (64) Hamblet, C. H., and McAlevy, A. (to E. I. du Pont de Nemours & Co., Inc.), Ibid., 2,557,282 (June 19, 1951). (65) Hearne, G. W., Evans, T. W., and Buls, V. W. (to Shell Development Co.), Zbid., 2,578,654 (Dec. 18, 1951). (66) Heider, R. L. (to Monsanto Chemical Co.), Ibid., 2,554,459 (May22, 1951). * (67) Ibid., 2,587,468 (Feb. 26, 1952). (68) Henderson, G. M., Discussions Faraday Soc., 1951, No. 10, 291-8. (69) Hickinbottom, W-.J., and Wood, D. G. M., Nature, 168, 33-4 (July 7, 1951). (70) Hillyer, J. C., and Edmonds, J. T. (to Phillips Petroleum Co.), U. S. Patent 2,551,675 (May 8, 1951). (71) Hinshelwood, C. N., Discussions Faraday SOC.,1951, No. 10, 266-8.
.
2051
(72) Hochwalt, C. A. (to Monsanto Chemical Co.), U. S. Patent 2,552,278 (May 8, 1952). (73) Hock, H., and Depke, F., Chem. Ber., 84, 349-56 (1951). (74) Howard, H. C. (to Carnegie Inst. of Technol.), C. S. Patent 2,555,410 (June 5, 1951). (75) Hull, D. C. (to Eastman Kodak Co.), Ibid., 2,552,175 (May 8, 1951). (76) Ibid., 2,578,306 (Dee. 11, 1951). (77) Hurley, T. F., J . Inst. Petroleum, 37, 517-34 (1951). (78) Hurn, R. W., and Hughes, K. J., S.A.E. Quart. Trans., 6, 24-35 (1952). (79) Jackson, J. L., IND. ENG.CHEM.,43, 2869-70 (1951). (80) Johnson, Robert (to Koppers Co., Ino.), U. S.Patent 2,568,639 (Sept. 18, 1951). (81) Jones, R. E. (to Merck & Co., Inc.), Ibid., 2,571,889 (Oct. 16, 1951). (82) Joris, G. G. (to Allied Chemical & Dye Corp.), Ibid., 2,546,639 (March 27, 1951). (83) Ibid., 2,546,640 (March 27, 1951). (84) Ibid., 2,577,768 (Dec. 11, 1951). (85) Kahler, E. J., Bearse, A. E., and Stoner, G. G., IKD.EXG. CHEM.,43,2777-81 (1951). (86) Keenan, V. J. (to United States Rubber Co.), U. S. Patent 2,555,976(June 5, 1951). (87) Landau, Ralph (to Chempatents, Inc.), Ibid., 2,574,644 ( S o v . 13, 1951). (88) Levedahl, W.J., and Howard, F. L., J . Research N a t l . Bur. Standards, 46,301-9 (1951). (89) Livengood, J . C., and Leary, W. A., IND.ENG.CHEZI.,43, 2797-805 (1951). (90) Lorand, E. J., and Reese, J . E. (to Hercules Powder Co.), G. S. Patent 2,548,435 (April 10, 1951). (91) Lowe, A. J., and Chapman, F., Petroleum (London), 14, 182-3, 195 (1951). (92) Lyn, W. T., and Moore, N. P. W., Fuel, 30, 158-66 (July, 1951). (93) McKeever, C. H. (to Rohm &: Haas Co.), U. S.Patent2,583,112 (Jan. 22,1952). (94) MacLean, A. F. (to Celanese Corp. of America), Ibid., 2,545,889 (March 20, 1951). (95) Mertz, C. W., Cutcher, H. W., and MoBride, J. A. (to Phillips Petroleum Co.), Ibid., 2,558,221 (June 26, 1951); 2,574,884 (Nov. 13, 1951). (96) Mikeska, L. A., and Young, D. W. (to Standard Oil Development Co.), Ibid., 2,554,259 (May 22, 1951). (97) Miller, R. J. (to California Research Corp.), Ibid., 2,576,625 (Nov. 27,1951). (98) Mungen, Richard, and Kratzer, hl. B., IND.ENG. CHEM., 43, 2782-7 (1951). (99) Murphy, C. R. (to Warren Petroleum Co.), U. S. Patent 2,579,847 (Dec. 25,1951). (100) Murray, M. J. (to Universal Oil Products Co.), Ibid., 2,580,184 (Dec. 25,1951). (101) Norrish, R. G. W., Discussions Faraday Soc., 1951, No. 10, 269-78. (102) O’Connor, J.A., Chem. Eng., 58, No. 10, 215,218 (1951). (103) Patai, S., and Hoffmann, J . Applied Chem., 2,8-11 (1952). (104) Perry, c. 7%‘. (to Phillip5 Petroleum CO.), abandoned application No. 121,229 (filed Oct. 13, 1949). (.I051 Pickering, H.S., and Linnett, J. W., Trans. Faraday Soc., 47, 1101-6 (1951). (106) Porter, Frank, and Cosby, J. N. (to Allied Chemical & Dye Corp.), U. S. Patent2,565,087 (Aug. 21, 1951). (107) Raine, T. L., and Garner, F. H., Trans. Faraday Soc., 47, 896-9 (1951). (108) R ~ N.~ V. , C., Winn, Hugh, and Shelton, J. R,, CHEM.,43,576-80 (1951). (109) Renner, H. 0. (to J. R. Short Milling Co.), U. S. Patent 2,573,358 (Oct. 30, 1951). (110) Retailleau, E. R., Rioards, H. A., Jr., and Jones, M. C. K., Am. Scientist, 39, 656-71 (1951). (111) Rifkin, E. B., Walcutt, C., and Betker, G. W., S.A.E. Journal, 60, 50-5 (February, 1952). (112) Robbins, W. E., Andette, R. R., and Reynolds, IV.E., S.A.E. Quart. Trans., 5,404-17 (1951). (113) Robertson, N. C., and Allen, R. T. (to Celanese Corp. of America), U. S. Patent 2,578,841 (Dec. 18, 1951). (114) Robinson, S. P. (to Phillips Petroleum Co.), Ibid., 2,561,996 (July24, 1951). (115) Rust, J. B., and MacKenzie, C. A. (to Montclair Research Corp. and Ellis-Foster Co.), Ibid., 2,572,876 (Oct. 30, 1951). (116) Satterfield, C. N., Kavanagh, G. M., and Resnick, H., IND. ENG.CHEM.,43,2507-14 (1951). (117) Sebastian, J. J. S., Ibid., 44, 1175-84 (1952). (118) Small, N. J. H., and Ubbelohde, A. R., Nature, 168, 201-2 (1951). (119) Spalding, D. B., Fuel, 30, 121-30 (1951).
INDUSTRIAL AND ENGINEERING CHEMISTRY
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(120) Sweeney, M-.J., 1x11. ENG.CHEY.,43, 2717 (1961). (121) Swern, D., and Knight, H. B. (to United States of America), U. S. Patent 2,572,892 (Oct. 30, 1951). (122) Thomas, J. R.. and Crandall, 1-1. IT-., IND.EEG.C H E x . , 43, 2761-3 (1951). (123) Toland, K.G., Jr. (to California Research Corp.), U. S. Patent 2,574,511 (Kov. 13, 1951). (124) Ibid., 2,574,512 (SOT.13, 1951). (125) Topps, J. E. C., J . Inst. Petroleunz, 37, 535-53 (1951). (126) Ulmer, R. C . , and Wood, R. JT., Inditstrli n n d Power, 61,92 6, 135 (1951). (127) Xalcutt, C.. a n d Rifkin, E. I added. Fordham and TTillianis (186) studied the mechanism and rate of the cuniene hydi*operoxide-iron reaction in the redoucatalyzed polymerization of acrylonitrile. Kolthoff, Medalia, and Youse (300) discussed the effectiveness of various sugars and their degradation products as activators for emulsion polymerizations. Kolthoff and Medalia (298, $99) reported the use of dihydroxyacetone and freshly preripitat ed ferrous sulfide in redox
