I&EC TRENDS
TODAY
can now be produced eficiently and economically by a new vacuum pumping system developed by Union Carbide’s Linde Division. Utilizing gas adsorption at cryogenic temperatures, Linde’s pumps have no moving parts or working $uids, thereby eliminating the danger of oil contamination. The first marketed unit will evacuate volumes of 20 cubic feet to vacuums of IO-6 to 70-7 torr in two or more stages in about four hours. Extremely clean vacuums
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and characterization has been initiated by the National Bureau of Standards. Partly supported by the Advanced Research Projects Agency, the new program will intensify existingprograms and initiate new ones. Of particular interest are crystals having piezoelectric and ferroelectric properties, crystal whiskers having unusual strength characteristics, crystalline materials that are especially resistant to extreme tempeatures on pressures, materials that may provide radiation shielding, and crystals transparent to particular wavelengths. The activities are divided into four general areas of investigation: crystal growth; deject characterization; physical properties; and crystal chemistry. An accelerated program of research on crystal growth
The reaction rate of Q gas may be found by heating it in a shock tube with a gas whose rate is known. The comparative technique has been developed by D r . Wing Tsang of the National Bureau of Standards. Preliminary experiments, which prove the validity of the technique, should lead to shock tube determination of the rate constants f o r many gas phase reactions. Despite the dt8culties of determining the actual temperature associated with the shock, the tube permits attaining high temperatures in a very short time and virtually eliminates wall efects. The new NBS technique also eliminates the need for knowing the temperature, thereby removing the major objection to the use of shock tubes.
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Extensive pilot studies in evaporation and crystallization are being conducted by Chicago Bridge and Iron Co. to obtain data for its own design department. The Pilot plant is available to outsiders on a per diem basis when it is not being used by CBiYI.
Organic semiconductors exhibit noticeable catalytic activity. The catalysts, synthesized at the Institut Francais du Petrole by condensation of unsaturated polymers Polydienes) with chloroanil and benzoquinone, have been efective in the decomposition of NZO, the dehydration of cyclohexanol, and the isomerization of I-butene. The temperature stability of these polymers and positive knowledge of the number and type of the active canters on the surface indicate that catalytic reactor design f o r some commercially important reactions can be greatly refined. In the decomposition of NzO one of the catalysts proved to be more than twice as efective as the best catalyst previously available (NiO)and provided about IOi9 active centers per gram of catalyst. Accurate knowledge of the number of active centers will be a boon to researchers and designers who were forced to guess heretofore. VOL. 5 6
NO. 5
M A Y 1964
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J Significant Organic Chemicals
HERCULES IS A PREFERRED SOURCE OF
PHENOL -
dk -E
H ' fR C U L f S
(U. S. P. SYNTHETIC)
Three factors have made Hercules a preferred source of Phenol: 0 0 0 Dependable supply from the U.S. pioneers of the cumenephenol process. 0 0 0 Rigidly controlled high quality. 0 0 0 Prompt shipments on short notice. For complete details about Phenol and the other "building blocks" above, contact Synthetics Department, Hercules Powder Company, 910 Market Street, Wilmington, Delaware 19899.
I N D I C A T O R S FOR TOMORROW of liquids that float on the top of the same or another yet miscible liquid-are being studied quantitatively by K. C. D.Hickman at Rochester Institute of Technology, Rochester, N . Y. Droplet formation is reproducible; so are interface properties, flow patterns, and other phenomena associated with the ((boules.” Required for Jotation are absence of foreign gas, electrical neutrality between drop and host liquid, and superheat. W i t h the right conditions, boules up to half the container diameter can be grown (see cut). Potential value of the investigations ranges from oceanography through liquid surface theory to simple, practical evaporation. Sessile drops-masses
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abpears to be shifting from the relatively empirical to a more systematic fundamental level, $ articles currently being considered for Publication are an indication. Since K. G. Denbigh’s initial treatment of open reacting systems in terms of nonequilibrium steady states [Trans. Faraday Soc. 40, 352 ( 1944)1, kinetics and reactor design have experienced tremendous theoretical growth. Denbigh’s treatment has been extended to include multibed and tubular reactors, and treatment of simultaneous and consecutive reactions seems to have reached some sort of theoretical maturity. Typical of these trends are two papers from University of Minnesota and one from Union Carbide, now being processed for publication in I@EC. Zeman and Amundsen have contributed a thorough explanation of continuous variable method for addition polymerization reactionsplus application of the method to most of the common reactor-reaction combinations. Ranz and Dickson discuss high gradient transfer-a subject of more than passing interest to reactor designers. Although formally unrelated to the other Minnesota paper, the Ranz-Dickson manuscript also puts a subject of great modern interest in a traditional context. And Szabo and Leathrum of Carbide’s Plastics Division developed a mathematical model for condensationpolymerization and have tested it with reactor data-thus demonstrating the conjdent consistent industrial application of these theoretical ideas. Similar techniques are being applied to nonreacting systems as well. Recently, Horn in England [Chem. Ing. TeLh. 36,99 (Feb. 7964)]has dealt with a multistage countercurrent contractor in terms of nonequilibrium steady states. The approach works as well for optimization as for design 2nd focuses attention on an ever-increasing need for more accurate data-a factor inherent in all modern approaches to tradztional problems. Successful design of industrial chemical reactors
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Kryptonation of solids provides a unique solution to many old problems, according to 0. M . Bizzell in a paper given at the recent ACS meeting in Philadelphia. Since the discovery that krypton is retained in solid structures and has a safe level of radioactivity, mechanistic determinations have been made much easier. I t is now possible to kryptonate either inert or reactive solids, pulverize them, and introduce the powder into the desired system. Simple and rugged radiotracer detectors are then used to follow flow patterns, jind leaks, determine structure, observe surface energy distributions, assist in the determination of reaction mechanisms, measure concentration distributions, etc. Safety and quantitative predictability will permit wide adaptability of the method. I t would seem that usefulness of the method is limited only by the sensitivity of the detector. Furthermore, using the radioactive property of the tracer to photosensitize a chart would permit further extension of the method to rate measurement and the determination of such illusive things as eddy distributions and the measurement of processes within moving boundary layers and adsorbed jilms. Practically any material can be kryptonated, and the radioactive half life is long ( 70.6 years).
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MAY 1964
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