Electrical studies of catalyst composites containing YBa_2Cu_3O_(7-x) and an insulator

摘要

The high temperature superconductor YBa2Cu3O7_x (YBCO) is a good mixed conductor at high tem-peratures. When its AC loss is reduced by the addition of an insulator it is efficient at absorbing energy in a reactor heated by RF power and can also effectively catalyse the oxidation of methane (the necessary oxygen being supplied directly from the easily removable oxygen in the YBCO) [1]. With the use of RF power, the catalyst alone absorbs energy, and gas-phase fouling reactions can be eliminated. The latter can be a considerable and costly problem, since apart from the loss of hydrocarbon, a signifi-cant proportion of oxygen may be used to combust any carbon deposits [2]. The magnitude and stability of the AC conductivity are important for efficient operation. Values of conductivity or activation energy which are too high will result in thermal runaway. If too low, it may not be possible to heat the material from room temperature [3].