PNNL

Abstract

The adsorption of HCN and the reaction of HCN with NO2 over Na-, and Ba-Y,FAU zeolite catalysts were investigated using in situ FTIR and TPD/TPR spectroscopies. Both catalysts adsorb HCN molecularly at room temperature, and the strength of adsorption is higher over Ba-Y than Na-Y. Over Na-Y the reaction between HCN and NO2 is slow at 473K. On Ba-Y HCN reacts readily with NO2 at 473K, forming N2, CO, CO2, HNCO, NO, N2O and C2N2. The results of this investigation suggest that initial step in the HCN+NO2 reaction over these catalysts is the hydrogen abstraction from HCN, and the formation of ionic CN? and NC? species. The formation of N2 can proceed directly from these ionic species upon their interaction with NO?. Alternatively, these cyanide species can be oxidized to isocyanates which then can be further transformed to N2, N2O and COx in their subsequent reaction with NOx.