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Dynamics of the methane pyrolysis on the ZrO2/SiC resistive catalyst was studied at various temperatures. At a temperature of 1300C, the conversion of methane passes through a maximum (55%) at the 60th minute, with the selectivity with respect to acetylene monotonically increasing during the whole experiment. The method of scanning electron microscopy with EDAX analysis demonstrated that, during the first 10 min of an experiment, the ZrO2/SiC is nearly fully carbonized at a temperature of 1300C. Also, a layered carbon coating is formed on the catalyst surface in the course of the experiment, with C2 hydrocarbons still present in pyrolysis products. It was shown that the carbon deposits formed on the catalyst surface are catalytically active in the process of acetylene formation. Regeneration of the catalyst does not fully restore its catalytic properties. [ABSTRACT FROM AUTHOR]

Effect of the calcination temperature of the MnOx/Ga2O3 system on its structural and catalytic properties in the reaction of oxidation of CO and hydrocarbons. The dependences of the catalytic activity of MnOx/Ga2O3 in the reactions of CO and ethane oxidation on the calcination temperature exhibit an extremal behavior. The maximum values of activity are observed upon calcination of the system at 700°C, i.e., at the temperature that is limiting for the existence of a solid solution of manganese ions in γ-Ga2O3. The structural changes occurring with increasing calcination temperature are accompanied by a substantial decrease in the specific surface area of a sample. The observed rise in the specific catalytic activity (by a factor of ~7 upon an increase in the preliminary-calcination temperature from 600 to 800°C) confirms that the thermal activation effect exists for the given system. [ABSTRACT FROM AUTHOR]