Inhibition of fire suppressants on the CO removal over ceria-supported transition metal catalysts

The CO elimination from fire smoke containing fire suppressants through transition metal oxides supported by ceria catalysts (M/Ce) faces new challenges. The effects of two typical fire suppressants (CF₃Br and NaHCO₃) on the conversion of CO and the evolution of intermediate species on three M/Ce catalysts (M = Cu, Co and Mn) were investigated. The impact mechanism of the fire suppressants was further revealed via in situ DRIFTS experiments for Cu/Ce catalyst in the absence and presence of fire suppressants. The results show that the activity and reusability of Cu/Ce and Co/Ce are decreased by the CF₃Br pretreatment but Mn/Ce exhibits a certain resistance. For the effect of NaHCO₃, the pyrolysis gases play a dominant role and its degree depends on the reaction temperature and the CO adsorption and activation capacity of catalysts. Moreover, in situ DRIFTS results reveal that the blocked reaction of adsorbed CO intermediates and oxygen species and the more severe masking of carbonates on the catalyst surface could be responsible for the decrease of the CO elimination performance due to the typical fire suppressants. This work can provide valuable insights for understanding the inhibition mechanism of fire suppression on CO elimination and exploring the resistance strategies to guarantee emergency rescue.