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The co-existence of independent sites on alumina as shown by the infrared spectra of chemisorbed acetylene and ethylene
Classified Abstracts 235--245 the range of relative coverage between 10 -e and 0.3. Temperatures between 63.3 and 90.2°K were used. The DubininRadushkevich isotherm equation was found empirically to describe all the data. This equation was also found to describe the isotherm data of others at low relative coverage on a variety of heterogeneous adsorbents. The energy distribution function giving rise to the Dubinin-Radushkevich isotherm is discussed. A simple analytical hypothesis is suggested for the extrapolation of isotherms on heterogeneous surfaces to the region of Henry's Law. (U.S.A.) (Author) J. P. Hobson and R. A. Armstrong, J. Phys. Chem., 67, Oct. 1963, 2000-2008. 16 235. A study of the adsorption and decomposition of hydrocarbons on clean iridium surfaces. (U.S.A.) The adsorption and decomposition of methane, ethane, and ethylene on iridium films prepared under ultra-high vacuum has been investigated. M e t h a n e adsorbed on films at 27 and 100 ° but did not decompose. Ethane decomposed on iridium (27 °) to hydrogen and methane and on iridium (100 °) to methane. The addition of oxygen to a clean iridium film greatly inhibited the subsequent decomposition of ethane to methane. Ethylene underwent self-hydrogenation to ethane on iridium (27 °, 100 °) and methane also was produced. The roughness factor of the iridium films was about seven. (U.S.A.) (Author) R. W. Roberts, J. Phys. Chem., 67, Oct. 1963, 2035-2038. 16 236. The co-existence of independent sites on alumina as shown by the infrared spectra of chemisorbed acetylene and ethylene.
(U.S.A.) D. J. C. Yates, and .P.J. Lucchesi J. Phys. Chem., 67, June 1963, 1197-1202. 16 237. The adsorption of methane and nitrogen on silica gel, synthetic zeolite, and charcoal. (U.S.A.) A. J. Kidnay and M. K. Hiza, J. Phys. Chem., 67, Aug. 1963, 1725-1727. 16 238. Heats of adsorption of amines, hydrocarbons, and water vapor on reduced and oxidized iron surfaces. (U.S.A.) Yung-Fang Yu Yao, J. Phys. Chem., 67, Oct. 1963, 2055-2061. 16 239. Influence of surface structure on adsorption : I. Thermodynamic properties of benzene absorbed on quartz. (U.S.A.) J. W. Whalen, J. Phys. Chem., 67, Oct. 1963, 2114-2120. 16 240. Surface concentration build-up during diffusion in porous media with dead-end pore volume. (U.S.A.) R. C. Goodknight and I. Fatt, J. Phys. Chem., 67, April, 1963, 949-951. 16 241. The effect of crystal size and gas adsorption on the L3 X-ray absorption edge of alumina-supported platinum. (U.S.A.) P. H. Lewis, J. Phys: Chem., 67, Oct. 1963, 2151-2156. 16 242. Adsorption of n-butane on vycor glass and effects ofoutgassing.
(U.S.A.) R. W. Kershaw and M. H. Panckhurst, J. Phys., Chem., 67, Oct. 1963, 2226-2227.
129
17.
Thermodynamics
17 Adsorption thermodynamics and the structure of crystal surfaces. See Abstr. No. 230. 17 The significance of cryogenic technique for the production of low pressures. See Abstr. No. 226. 17 243.' Vapor pressure of molybdenum troxide. (U.S.A.) E. A. Gulbransen, K. F. Andrew, and F. A. Brassart, J. Electrochem. See., 110, March 1963, 242-243. 17 : 41 244. Enhancement of diffusion-limited rates of vaporization of metals. (U.S.A.) On a theoretical basis, it is shown that the rate of vaporization of metals in a stream of a neutral atmosphere should increase with increasing partial pressure of a reacting gas, such as oxygen. Considering the vaporization of a metal in a stream of argon ÷ oxygen, the enhanced vaporization is basically a vaporizationoxidation process involving the counter diffusion of oxygen (or oxidizing species) and metal vapor within the gaseous boundary layer. These interact to form a metal oxide mist in the gas close to the metal-gas interface. As a result of this reaction, the partial pressure of oxygen influences the rate of vaporization of the metal. As the partial pressure of oxygen in the gas stream increases, the thickness of the boundary diffusion layer for metal vapor decreases, resulting in an increased rate of vaporization. At a critical partial pressure of oxygen, the vaporization of the metal is close to the maximum rate obtainable in vacuo. When the oxygen pressure exceeds this critical value, the flux of oxygen toward the surface is greater than the counter flux of the metal vapor, and consequently a liquid or a solid oxide layer forms on the metal surface and vaporization practically ceases. The experimental results obtained on the rate of vaporization of copper, nickel, cobalt, iron, manganese, and chromium in argon + oxygen mixtures verify the validity of the above theoretical consideration. Similarly, it is shown that the rate of vaporization of molten silicon into argon can be increased by introducing nitrogen into the stream. In this system, the formation of silicon nitride, by reaction of silicon vapor with nitrogen close to the metal surface, provides a sink for the vapor and gas species ; this results in an enhanced rate of vaporization of silicon. (U.S.A.) (Author) E. T. Turkdogan, P. Grieveson, and L. S. Darken, J. Phys. Chem., 67, Aug. 1963, 1647-1654. 17:52 245. A thermodynamic study of the tungsten-oxygen system at high temperatures. (U.S.A.) The sublimation behavior of the tungsten-oxygen system has been investigated over the temperature range 1300 to 1600°K by means of mass effusion studies, mass spectrometric observations, chemical analyses, and X-ray diffraction examination of the condensed phases. Measurements were carried out on compositions ranging from WO1.80 to WO3. In all cases the thermodynamically important vapor species are W401~, W3Op, WaOs, and W206. Univariant behavior was observed for the solid phases W-WO2, WO2-WxsO49, WlsO4.-W~0Oss, W,0Oss-WO2.,6 and WO2.96. T h e composition WOe.ge probably represents the azeotropic composition of the WOs-2 solid solution produced by the vacuum and is the only single phase which evaporates congruently below 1550°K. Except for the W2oOss-WO2.96 mixture in which the composition of the vapor phase is between those of the solid phases, all other phases and mixtures of two solid phases evaporate incongruently, since the vapor phase is richer
(U.S.A.) D. J. C. Yates, and .P.J. Lucchesi J. Phys. Chem., 67, June 1963, 1197-1202. 16 237. The adsorption of methane and nitrogen on silica gel, synthetic zeolite, and charcoal. (U.S.A.) A. J. Kidnay and M. K. Hiza, J. Phys. Chem., 67, Aug. 1963, 1725-1727. 16 238. Heats of adsorption of amines, hydrocarbons, and water vapor on reduced and oxidized iron surfaces. (U.S.A.) Yung-Fang Yu Yao, J. Phys. Chem., 67, Oct. 1963, 2055-2061. 16 239. Influence of surface structure on adsorption : I. Thermodynamic properties of benzene absorbed on quartz. (U.S.A.) J. W. Whalen, J. Phys. Chem., 67, Oct. 1963, 2114-2120. 16 240. Surface concentration build-up during diffusion in porous media with dead-end pore volume. (U.S.A.) R. C. Goodknight and I. Fatt, J. Phys. Chem., 67, April, 1963, 949-951. 16 241. The effect of crystal size and gas adsorption on the L3 X-ray absorption edge of alumina-supported platinum. (U.S.A.) P. H. Lewis, J. Phys: Chem., 67, Oct. 1963, 2151-2156. 16 242. Adsorption of n-butane on vycor glass and effects ofoutgassing.
(U.S.A.) R. W. Kershaw and M. H. Panckhurst, J. Phys., Chem., 67, Oct. 1963, 2226-2227.
129
17.
Thermodynamics
17 Adsorption thermodynamics and the structure of crystal surfaces. See Abstr. No. 230. 17 The significance of cryogenic technique for the production of low pressures. See Abstr. No. 226. 17 243.' Vapor pressure of molybdenum troxide. (U.S.A.) E. A. Gulbransen, K. F. Andrew, and F. A. Brassart, J. Electrochem. See., 110, March 1963, 242-243. 17 : 41 244. Enhancement of diffusion-limited rates of vaporization of metals. (U.S.A.) On a theoretical basis, it is shown that the rate of vaporization of metals in a stream of a neutral atmosphere should increase with increasing partial pressure of a reacting gas, such as oxygen. Considering the vaporization of a metal in a stream of argon ÷ oxygen, the enhanced vaporization is basically a vaporizationoxidation process involving the counter diffusion of oxygen (or oxidizing species) and metal vapor within the gaseous boundary layer. These interact to form a metal oxide mist in the gas close to the metal-gas interface. As a result of this reaction, the partial pressure of oxygen influences the rate of vaporization of the metal. As the partial pressure of oxygen in the gas stream increases, the thickness of the boundary diffusion layer for metal vapor decreases, resulting in an increased rate of vaporization. At a critical partial pressure of oxygen, the vaporization of the metal is close to the maximum rate obtainable in vacuo. When the oxygen pressure exceeds this critical value, the flux of oxygen toward the surface is greater than the counter flux of the metal vapor, and consequently a liquid or a solid oxide layer forms on the metal surface and vaporization practically ceases. The experimental results obtained on the rate of vaporization of copper, nickel, cobalt, iron, manganese, and chromium in argon + oxygen mixtures verify the validity of the above theoretical consideration. Similarly, it is shown that the rate of vaporization of molten silicon into argon can be increased by introducing nitrogen into the stream. In this system, the formation of silicon nitride, by reaction of silicon vapor with nitrogen close to the metal surface, provides a sink for the vapor and gas species ; this results in an enhanced rate of vaporization of silicon. (U.S.A.) (Author) E. T. Turkdogan, P. Grieveson, and L. S. Darken, J. Phys. Chem., 67, Aug. 1963, 1647-1654. 17:52 245. A thermodynamic study of the tungsten-oxygen system at high temperatures. (U.S.A.) The sublimation behavior of the tungsten-oxygen system has been investigated over the temperature range 1300 to 1600°K by means of mass effusion studies, mass spectrometric observations, chemical analyses, and X-ray diffraction examination of the condensed phases. Measurements were carried out on compositions ranging from WO1.80 to WO3. In all cases the thermodynamically important vapor species are W401~, W3Op, WaOs, and W206. Univariant behavior was observed for the solid phases W-WO2, WO2-WxsO49, WlsO4.-W~0Oss, W,0Oss-WO2.,6 and WO2.96. T h e composition WOe.ge probably represents the azeotropic composition of the WOs-2 solid solution produced by the vacuum and is the only single phase which evaporates congruently below 1550°K. Except for the W2oOss-WO2.96 mixture in which the composition of the vapor phase is between those of the solid phases, all other phases and mixtures of two solid phases evaporate incongruently, since the vapor phase is richer