Catalytic effect of Na–Fe on NO–char reaction and NO emission during coal char combustion

The catalytic reduction of NO over coal-derived chars and the catalytic effect of Na–Fe on NO emission during char combustion were investigated in a quartz fixed bed reactor. The catalytic characteristics of Na and Fe in the NO–char reaction were studied and compared in detail. The results show that the catalytic activity of Na depends greatly on its loading amount, while the activity of Fe is more sensitive to temperature. Na–Fe composite catalysts were also prepared with chars as support. Synergistic effect was found both in the reduction of NO and the char combustion. The Na–Fe composite catalysts exhibit significantly higher catalytic activity than the mono-metallic catalysts with the same metal loading amount. It is intriguing to note that the effectiveness of the catalysts on reducing NO emission during char combustion is in the same order as that in the NO–char reaction, i.e. the chars with catalysts not only have high activity in NO–char reaction but also emit less NO during their combustion.