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

Abstract

Denitration of a highly concentrated sodium nitrate (NaNO 3) aqueous solution via a catalytic reduction method using a palladium-copper catalyst supported on carbon powder (Pd-Cu/C) and hydrazine (N 2H 4) was investigated. It was demonstrated that nitrate ion (NO 3-) in a 5 mol L -1 NaNO 3 solution was completely reduced through an intermediate nitrite ion (NO 2-) to nitrogen compounds such as nitrogen, nitrous oxide, and ammonia. By comparing the reaction rates of NO3 7 and NO 2- obtained using catalysts with various Pd-Cu compositions and different reductants (hydrogen (H 2) or N 2H 4), it was determined that the catalyst with a molar ratio of Pd:Cu = 1:0.66 provides the maximum reaction rates for NO 3- and NO 2- using N 2H 4, and that not only the reactions of NO 3- and NO 2- but also that of N 2H 4 were affected by the Pd-Cu composition. © 2012 Atomic Energy Society of Japan. All rights reserved.