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system permits much higher temperatures, sometimes exceeding 10,000° K. The high-intensity arc has been studied for some time but only recently have there been attempts to use it for hydrocarbon synthesis. Prof. Korman calls his system the fluid convection cathode (FCC). Prof. Korman used the FCC to study the synthesis of hydrocarbons. From 10,000° to 20,000° K., the hydrogen in the feed is monatomic and impinges on the carbon anode at its sublimation temperature of about 4000° K. in the arc crater. Gas samples drawn from this region during operation are found to contain hydrocarbons. The composition of the hydrocarbons depends on the flow rate of the hydrogen fed to the arc, the temperature, and the residence time of the arc effluent in the downstream hot zone. The composition of the confining wall also has an effect. Hydrogen, though always present in stoichiometric excess, causes a transition of the hydrocarbon product ranging from 100% acetylene at low flow rates, to mixtures of acetylene and methane with occasional amounts of propylene. At high flow rates methane is predominant. When steam is substituted for hydrogen in the FCC arc, the principal hydrocarbon component is methane. As the flow rate increases, acetylene predominates. A solid, pulverized petroleum residue fed in entrained argon into the FCC arc produces acetylene predictably under conditions corresponding to the analogous hydrogen feed. Dr. Korman believes that the results from his studies thus far indicate that the FCC arc may be useful in a number of applications in the gasification of coal and other carbonaceous feeds.
Fluorocarbon plastics from plasmas FLUORINE—A new technique for making poly(carbon monofluoride) (CMF), plasma synthesis, has been developed by Dr. Richard J. Lagow and his associates at Massachusetts Institute of Technology. He produces CMF in a fluidized plasma with graphite as the solid phase and fluorine as the fluidizing gas. The technique has several advantages over previous thermal methods, including lower temperature and lower energy needs. CMF, obtained from the fluorination of graphite, is the most thermally stable polymeric fluorocarbon known. It is indefinitely stable to 600° C. and stable for short periods to 800° C. Recent studies of the lubrication properties of CMF at Lewis Research Center of the National Aeronautics and Space Administration and at Frankfort Arsenal have excited new interest in the material. These studies show that CMF, as a solid lubricant under extreme conditions such as high and low temperatures and heavy loads, is very much superior to graphite or molybdenum sulfide. CMF also shows promise as a cathode material in high-energy batteries. One of the problems, though, is how to make the new material. Dr. Lagow's unusual synthesis is an example of the use of a fluidized plasma bed to prepare an industrially important compound. And it also demonstrates the advantages of a fluorine plasma in preparative fluorine chemistry. The gas temperature of the plasma in his technique is less than 150° C.— a much lower temperature than that used in other thermal approaches. The amount of energy used is much less than that required for a furnace of corresponding size maintained at 600° C. Also, it may prove easier to generate a large plasma than to keep a larger furnace uniformly in the narrow temperature range required for synthesizing snow-white CMF by thermal means.
Oil shale potential surveyed l&EC—With alternate energy sources looming larger in the future, industry is taking a harder look at their development. One source that appears to be among the easier to exploit in the short term is oil shale. Although the active lifetime of this source of oil and gas may be only a generation, it is ready for immediate development on a commercial scale. Oil shale really isn't a shale at all but a marlstone containing large amounts of organic matter. It may be pictured as an inorganic matrix in which an organic material resides, Dr. Arnold H. Pelofsky of Cities Service Research and Develop-
ment Co. told the meeting. The organic material is called kerogen. The relation of the kerogen to the matrix includes some primary valence bonding with the alkaline earth carbonates. Thus, the raw shale must be acidified before the kerogen can be removed. Acidification removes the calcite and dolomite portions of the shale. Also, some of the porphyrins in the shale may chelate with some of the minerals. Acidification circumvents this problem by removing much of the mineral content. Because kerogen has many polar sites, it is intimately mixed with minerals that are known adsorbents. These various types of bonds explain why a purely physical separation of the kerogen is so difficult. The compressive strength of oil shale is higher than most people suspect, sometimes up to 30,000 p.s.i. In fact, the compressive strength is more than sufficient to permit conventional mining of the material without incurring safety problems. Oxidation and degradation studies of kerogen indicate that at least two major types of compounds exist in the shale. One type is predominantly hydrocarbon in nature with straight chains, rings, and some heterocyclic structures that produce on processing most of the oil, wax, and resins by thermal degradation. The second type is essentially a heterocyclic material that is partially converted to oil on processing but to mainly hydrogen-deficient materials which, in turn, yield mostly carbon residues and gas. According to Dr. Pelofsky, extraction tests of kerogen from the Green River formation in Wyoming show that the material consists of 5 to 10% chain paraffins, 20 to 25% saturated cyclic structures, 10 to 15% aromatics, and 40 to 45% heterocyclic structures. The identification of the various types of compounds in the raw kerogen indicates the biological origin of the elements in the kerogen. Chemical analyses and the results of x-ray, infrared, and ultraviolet analyses of Green River kerogen all indicate that it is predominantly naphthenic. Pyrolysis of oil shale is probably diffusion limited, Dr. Pelofsky says. Heat must diffuse into the shale and the products must diffuse out of a structure that has essentially no pores. As pores develop during pyrolysis, when the products leave the shale matrix, the diffusion characteristics change. Although the pyrolysis kinetics are grossly first order, the quality of the products is a function of the temperature of pyrolysis. The higher the temperature, the more gas and aromatics are formed. Whether mineral content of the shale is involved in any way in the pyrolysis process isn't certain. However, the work of many investigators over the past 50 years shows that more product is recoverable as oil if the residence time is relatively short and the shale particle size is relatively small. April 23, 1973 C&EN
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