Applicability of a catalytic reduction method using a palladium-copper catalyst and hydrazine for the denitration of a highly concentrated nitrate salt solution

Kadowaki, Haruhiko ; Meguro, Yoshihiro  

Denitration of a highly-concentrated sodium nitrate (NaNO) aqueous solution was studied with a catalytic reduction method using a catalyst of palladium-copper supported on carbon powder (Pd-Cu/C) and hydrazine (NH). It was demonstrated that nitrate ion (NO) in 5 mol L NaNO solution was completely reduced through an intermediate nitrite ion (NO) to a nitrogen compound such as nitrogen, nitrous oxide or ammonia. By comparing reaction rates of NO and NO obtained using catalysts with various Pd-Cu composition and different reductants (hydrogen (H) or NH), it was found that the catalyst having metal ratio of Pd : Cu = 1 : 0.66 brought maximum reaction rate of NO and NO by using NH, and that not only reactions of NO and NO but also reaction of NH were affected by the Pd-Cu composition.