The effect of 25 ppm SO_2 with respect to the complete oxidation of methane over supported palladium catalysts has been examined. Pd nitrate was impregnated onto alumina, Ba-modified alumina and La-modified alumina by incipient wetness impregnation. The calculated metal loading was 2.5 wt%. Two different sets of catalysts have been prepared: one calcined at 500 °C and the other at 1000 °C. The main purpose of these two calcinations temperatures was to obtain different metal particle sizes. The results show that the combustion activity is strongly affected by the nature of the support when large particles are present. On the other hand, the small Pd particles exhibit similar behavior regardless of the nature of the support. When SO_2 is added to the gas stream, a strong deactivation is observed and the presence of additive to stabilize the support increases the loss of activity of the supported Pd particles.
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