The effect of the preparation conditions of Pt/ZSM-5 upon its activity and selectivity for the reduction of nitric oxide

摘要

The selective catalytic reduction (SCR) of nitric oxide by propene in the presence of oxygen over Pt/ASM-5 has been studied on samples pre-treated under different conditions. It has been found that reduced samples before SCR of nitric oxide (pre-reduced samples) exhibit a much higher catalytic activity than the oxidized ones before SCR of nitric oxide (pre-oxidized samples). Moreover, the reactions on pre-reduced samples demonstrate the similarity both in activity and selectivity, whereas different activities have been found on pre-oxidized samples. The rate of NO_2 formation rapidly increased above the temperature of maximum catalytic activity for NO reduction. It is therefore suggested that partial reduction occurs on pre-oxidized samples during the NO+C_3H_6+O_2 reaction.