Reducing nitrates to nitrogen or ammonia in acidic effluents, by hydrogenation over metal catalyst, with preliminary neutralization to prevent formation of hydroxylamine

摘要

Method for reducing, to nitrogen and optionally ammonia, nitrates in aqueous acidic effluent by hydrogenation in presence of heterogeneous catalyst (A), optionally containing at least one metal dopant. Method for reducing, to nitrogen and optionally ammonia, nitrates in aqueous acidic effluent by hydrogenation in presence of heterogeneous catalyst (A), optionally containing at least one metal dopant. The effluent (i) contains 0.05-20 wt.% nitrate; (ii) has total acid content at most 20 wt.% and (iii) is neutralized, before reaction, so that the pH of the medium at the end of the reaction (if discontinuous) or during reaction (if continuous) is at least 3.