Synthetic Phenol M. CRAWFORD, Vice President for Development and Research, Durez Plastics & Chemicals, Inc., N o r t h Tonawanda, Ν . Y.
ROBERT
The Durez
synthelic
phenol
XN -June 1940, a commercial plant for the production of 12,000,000 lb. a year of phenol from benzene by a new synthesis was successfully put into commercial p r o duction b y Durez Plastics & Chemicals, Inc., at N o r t h Tonawanda, Ν . Υ. After six y e a r s of highly successful operation and m a n y changes, both physical a n d cheinical, especially with respect to new catalysts, t h e plant has shown t h a t it c a n be operated economically on a commercial basisΛ brief history of the development of this G e r m a n process follows. Shortly after the Armistice of 1918, in conformity with the policies of German industrialization, F. Rasehig, G.m.b.H. Ludwigshafen, Iihein, embarked upon the commercial production of phenolfoimaldehyde resins arid compounds under the invaluable guidance of M . Kocbner, who has published much in t h e chemical lit.era.ture on his work on phenolic a n d other resins. As a source of phenol, t h e Rasehig com pany drew upon its own production from the distillation of coal tar, in which indus try D r . Raschig's company has long been known. Large quantities of a very p u r e grade of phenol soon became necessary a n d were initially supplied by pure phenol purchased from I . G. Farben which oper ated a plant functioning on t h e well-known sulfonation process. In consideration of installing their own synthetic phenol plant, t h e Raschigs (father a n d two sons, K u r t and K l a u s , doctors of chemistry from Heidelberg University) investigated t h e economics of the "well-known syntheses from benzene by way of sulfonation and caustic fusion, VOLLIME
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and b y way of chlorination and alkali hydrolysis under pressure (referred to in G e r m a n y as t h e I . G . process and the R u t g e r ' s process, respectively). The re sults of t h e s t u d y of t h e economics of these available processes m a d e clear the fact t h a t t h e Rasehig company would not be able t o m a r k e t the large q u a n t i t y of by products yielded by these processes, at prices which would result in an attractive cost of phenol, and D r . Rasehig decided, in 1928, t o develop a n original synthesis specifically directed toward a process which, as he p u t it, "would yield only a few p e r cent of by-products and not sev eral hundred per c e n t " . T o this end, W a l t h e r Prahl (Heidelberg) was given charge of the development, being assisted by Wilhelm M a t h e s (Heidelberg) in charge of a number of research chemists, and m u c h work was done to develop new technology of chlorination and pressure hydrolysis of the Rutger's process but w i t h o u t notable success. A t t e n t i o n w a s t h e n directed, at the suggestion of Friedrich Bergius of coal hydrogénation fame, to t h e catalytic, vapor phase hydrolysis of monochlorobenzene with water, which w a s then well represented b y the work of Bergius and M e y e r in Germany, and of Bertch and J e n k i n s in the U . S. A . As a result of m u c h fundamental research on t h e p a r t of Heidelberg students, which involved a classification of metals and nonmetallic radicals as catalysts for the hydrolysis of monochlorobenzene by water, a catalyst was finally found which was b o t h efficient a n d economical. A large- l a b o r a t o r y a p p a r a t u s w a s finally put into continuous operation a t Raschig's
» » J A N U A R Y
2 7,
1947
plant producing approximately 1 kg. of phenol per day and means were developed to recover the hydrochloric acid in t h e salable form of 18 Be. muriatic acid. Typical of German resourcefulness, a suggestion was m a d e by one of the chemists t h a t t h e old Deacon chlorine process might be modified in such m a n n e r as t o oxidize the chlorine from the recovered hydrochloric acid, in the presence of benzene vapor, to form monochlorobenzene. After m a n y unsuccessful trials this scheme was made to operate by the successful development of a catalyst which would function at temperatures below 250° C. and which was also efficient and economical. As a result of the above two pertinent developments, it was obvious, in 1931, that a new synthesis for phenol had really been developed according to the wishes of Dr. Rasehig and that it was desirable, then, to erect a pilot plant to test out the scheme for its commercial aspects. Since Germany's economic situation in 1931 was such t h a t there was no money to erect a pilot plant, negotiations were consummated with one of the large chemical companies in the United States to accomplish this end, and Dr. Prahl spent t h e most of 1931 in this country developing the design of a five-ton-per-day unit. This work appeared to be unfruitful, so Dr. Prahl returned t o Germany to devise another method of approach. In 1933, successful negotiations were consummated with a large chemical company in Lyons, France, and a five-ton-perday unit was erected and put into partially successful operation. Erection of t h e French unit had hardly been started when, with the help of the Xazi regime, the Raschigs began to build their own five-ton-per-day unit at Ludwigshafen. This unit had begun to function early in 1935 although there were the usual faults, or "bugs", present requiring elimination. Unsuccessful a t t e m p t s were m a d e in 1935 and 1936 to interest United States companies in the rights to the p a t e n t s and to the end t h a t a large commercial unit would be built. In 1937 Durez Plasties & Chemicals, Inc. (then General Plastics, Inc.), inspected the unit, approved, consummated a contract, a n d in J u n e of 193S design and erection started a t North Tonawanda, X. Y., under t h e general direction of the writer and with t h e invaluable guidance of Dr. Prahl, who came here for the purpose. In t h e design of the Durez plant m o s t of the known faults of Ludwigshafen pilot plant were corrected while retaining the fundamental chemical phases of the process. Perhaps the m o s t serious process difficulty, made manifest during the first six m o n t h s ' operation of the plant, w a s the failure of t h e vapor mixer for uniformly mixing benzene, air, and hydrochloric acid (all in vapor form at 200° C.) which con235
stitute the reactants supplied the first (chlorination) stage. This failure was the result of inability to design practical vapor line expansion joints to carry HC1:H 2 0 vapor from four HC1 evaporators to a common point in the vapor mixer body. After temporary repairs to carry the plant in operation successfully through the first year's operation, a partial solution to the problem was made in 1941 and in 1942 the final solution was reached which was astounding in its simplicity. By the end of 1942, the design faults,
"bottlenecks", fctad become manifest, and were corrected o n e by one until now the numerous steps -constituting the process are balanced. U n d e r present operating con ditions the plan-t is capable of producing at least 20,000,000 lb. of USP phenol per annum. The so-called "corrosion" features of the process are absent, owing to design inno vations whichfciavegreatly reduced main tenance and repair by comparison with the German plant experience—in fact, corro sion due to Irydrogen sulfide in cooling
water pumped from underground demands far more "corrosion" maintenance than the HC1 on the process side. The Durez process produces by-prod ucts in the form of dichlorobenzenes from the chlorination stage, and polydiphenyl compounds from the hydrolysis stage, in the respective amounts of 6 and 2% of the USP phenol output. The dichloro benzenes are marketed in crude form at a respectable credit, while the polydiphenyl compounds (called phenol tar) are sold in the form of a resin compound.
Lamp Filament to Atomic Pile JL HREE tons of pure uranium where none was before. This was the ultimate result of efforts launched by the Westinghouse Electric Corp/s laboratories in 1922 in the search for new lamp filament materials. Uranium, located below tungsten in the Mendeleeff Table, was a logical choice and although it did not prove successful as a lamp filament, the knowledge gained in producing the metal for experimental pur poses proved a vital factor in the develop ment of the atomic bomb. These and other facts were brought out at a recent meeting of the Electrochemical Society's Metropolitan Section in New York City where some of the more recently developed uses as well as methods of preparation and properties of uranium, zirconium, and thorium were discussed by J. W. Marden, W. C. Lilliendahl, and D. M. Wroughton, all of Westinghouse Electric Corp.'s Lamp Division Research Laboratory. Uranium Late in 1941 when the Manhattan Proj ect began to look about for a source of uranium metal for experimental purposes it found that the only source of reasonably pure metal was the Westinghouse labora tory which had been producing uranium in small quantities for its experiments on the use of uranium as a lamp filament. Dr. Wroughton stated that at the time quan tity production of uranium was proposed the Westinghouse laboratory had had ex perience with two processes, either of which could be used. In deciding which process to apply, the availability of raw materials and the purity of product were primary considerations. The first process described by Dr. Wroughton was worked out by Marden and Rentschler and comprised the reduc tion of uranium double fluoride or uranium oxide with calcium in the form of calcium metal and calcium chloride. At the time that commitments were being made, early in 1942, no quantity supply of redistilled high purity metallic calcium was known.; therefore it was decided to turn to the electrolytic process. The electrolytic process was worked oiit by Driggs and Lilliendahl who succeeded 836
in. making urandum metal b\' electrolyzing rvUF 5 in a fused mixture of sodium chlo ride and calciuzm chloride. For this proc ess uranous fluoride was required which Westinghouse ^vas able to make in fairly pure form in i t s own laboratory according t o Dr. Wrougrtton. Calcium chloride and sodium chloride were obtainable in high purity from chemical manufacturers. The first order was received in December 1941 and was For 10 kg. of uranium metal which seemed a large quantity at the time. T h e order w a s filled by using two small laboratory furnaces, a few wooden tubs on tile roof utilizing sunlight for the photo chemical reduction of solutions of uranyl nitrate to ΚΙΓΡβ, arid a vacuum melting apparatus for the fusion of the metallic powder. Dr. "Wroughton added, "For the most part, the 10 kg. was supplied in a wide variety of shapes and sizes for the use of physicists who were making measurements a n d calculations for the plutonium piles. Articles varied from east spheres with pipes through the center to spirals of square wire and m a n y others which taxed the in genuity of the men and the facilities of the laboratory." Increased production was obtained by multiplying ttie laboratory setup, as there was no time For development work. The KUF 5 was soo>n replaced by uranium tetrafluoride and dependence upon the weather was no longer a factor. This uranium tetrafluoride was produced by hydrofluorination of t h e oxide. By January 1943, production ha.d reached 500 lb. per day and the cost had fallen from $1,000 to less than $22 per lb., when the electrolytic process Tvas superseded by a cheaper and simpler process. While not ultimately the best method, the electrolytic process saved many months of precious time. D r . Wroughton closed by saying t h a t a great amount of research was carried OIL in connection with the proc ess and that a s yet most of the details are secret. Zirconium The principal efforts of industrial re search workeors with zirconium are directed toward prodxicing a cold-ductile product CHEMICAL
which can be produced cheaply enough so that zirconium can be made in quantity and its usefulness in electronic and related fields be adequately exploited, stated Dr. Lilliendahl. A ductile form is now pro duced commercially by the thermal decom position of zirconium iodide which is formed by the action of iodine vapor on zirconium powder. Attempts have been made to produce cold-ductile zirconium by reduction of the oxide, chloride, and potas sium zirconium fluoride, with reducing agents such as sodium, calcium, and mag nesium. Some degree of success has been obtained by W. Kroll of the Bureau of Mines in the reduction of zirconium chlo ride with magnesium, and Dr. Lilliendahl reported, "the process is ingenious al though somewhat complicated and re quires considerable equipment". I n work along the same lines Westinghouse has pro duced sintered zirconium compacts with a hardness of Vickers 183 (Rockwell Β 90) which may be easily machined, tapped, and drilled, and melted zirconium in 30to 50-gram melts which is harder than sintered zirconium but which also may be machined, tapped, and drilled. Thorium Thorium has been prepared using potas sium thorium fluoride in an electrolytic process similar to that used for uranium production. Dr. Lilliendahl stated that thorium metal has also been prepared by calcium reduction of thorium oxide in the presence of calcium chloride and added that future work would probably be con cerned mainly with the refinement of present techniques. Some of the properties of thorium metal reported by Dr. Lilliendahl are t h a t it is very soft with a Vickers hardness of about 100. A freshly prepared surface is bright but becomes coated with a film, of oxide which protects the metal from further at tack. The density of the sintered metal is approximately 11.3 and the melted metal 11.5. The x-ray density as reported by Hull is 11.7. I t may be cold rolled into wire or sheet and may be cold swaged but it is not readily adaptable to cold drawing because of its low tensile strength. AND
ENGINEERING
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