Mechanistic study of the hydrogenolysis of neopentane on iridium

Technical Report · Tue Jan 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/5183125· OSTI ID:5183125

Kinkade, N. E.

Reaction of hydrogen and neopentane on iridium films resulted in the production of methane as the only product in the temperature range 403 to 473K. Pressures were varied over the ranges 1 to 400 millitorr for neopentane and 20 to 3000 millitorr for hydrogen. The limiting orders of the reaction with respect to hydrogen were found to be +2.0 and -0.1, and with respect to neopentane were +0.95 and -0.80. The order with respect to the partial pressure of methane was -0.03 or essentially zero. Flash desorption experiments indicated that no hydrocarbons could be desorbed from the sample. Deuterium exchange experiments indicated that once neopentane was adsorbed onto the iridium film at 468K it did not desorb without first undergoing carbon-carbon bond scission. A mechanism involving the reversible, dissociative adsorption of hydrogen and the irreversible, dissociative adsorption of neopentane was proposed. The neopentane dissociates into single carbon atom fragments on the surface and the surface concentrations of these fragments, C*, CH*, CH/sub 2/* and CH/sub 3/*, and H* vary depending upon the reaction conditions. At neopentane pressures >10 millitorr the surface species CH/sub 3/*, CH/sub 3/* and H* are predominant, while at neopentane pressures <2 millitorr, the concentration of the CH* species is also significant.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5183125
• Report Number(s): IS-T-909
• Country of Publication: United States
• Language: English

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