|Author||Stoddart, C. T. H. ♦ Pass, G. ♦ Burwell, R. L. (Jr.)|
|Source||United States Department of Energy Office of Scientific and Technical Information|
|Subject Keyword||CHEMISTRY ♦ ACTIVATION ENERGY ♦ ADSORPTION ♦ ALKANES ♦ BUTANE ♦ CATALYSIS ♦ CHEMICAL REACTIONS ♦ CHROMIUM OXIDES ♦ COLLOIDS ♦ CYCLOALKANES ♦ DETECTION ♦ DEUTERIUM ♦ ETHANE ♦ ETHYL RADICALS ♦ HEXANE ♦ HYDROCARBONS ♦ ISOTOPIC EXCHANGE ♦ METHANE ♦ METHYL RADICALS ♦ MOLECULES ♦ OCTANE ♦ PENTANE ♦ PROPANE|
|Abstract||The investigation of isotopic exchange on a chromia catalyst between deuterium and these various hydrocarbons are reported: the cycloalkanes, cyclopropane to cyclooctane, methane, ethane, hexane, and 2.3-dimethylbutane. At 2O0 deg C, the rates of exchange relative to cyclohexane are: cyclopropane, 50; ethylcyclobutane and cyclooctane, 5; ethane, 0.13. The others fall in the range, 1 to 3, except for methane which is about twice ethane. The activation energies of exchange of cyclopropane and of ethane are 7 and 21 kcal. Cyclopropane exchange can be detected even at 25 deg C, and, at 100 deg C, ring opening with an activation energy of 12 kcal becomes detectable. The exchange patterns of ethane, 3.3-dimethylpentane, and cyclopropane very closely follow the random distribution characteristic of a process which introduces but one deuterium atom per adsorption step. For the others, at about 2OO deg C, 95 to 99% of the exchanged molecules follow such a pattern. A few per cent follow a pattern involving extensive multiple exchange, and with cycloalkanes, a few per cent appear as excess cycloalkane-d/sub 2/ and -d/sub 3/. (auth)|
|Learning Resource Type||Article|
|Publisher Department||Northwestern Univ., Evanston, Ill.|
|Journal||Journal of the American Chemical Society|
|Organization||Northwestern Univ., Evanston, Ill.|
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