Pd-Cu catalysts supported on anion exchange resin for the simultaneous catalytic reduction of nitrate ions and reductive dehalogenation of organochlorinated pollutants from water

[Display omitted] •The deposition procedure of second metal strongly affects Pd-Cu/resin performances.•A two-step catalyst synthesis protocol: ion exchange-surface reduction was selected.•Pd-Cu catalyst is effective on simultaneous NO3− reduction and 4-CP dechlorination.•The catalyst shows good stability for 100 h of test time. The present work proposes the simultaneous removal of these classes of pollutants by a catalytic hydrotreatment processes. For this purpose, bimetallic Pd-Cu catalysts (with mass ratio Pd:Cu of 4:1) supported on macroporous strong base anion resin were prepared by different methods. The catalysts were characterized (by XRD, SEM-EDX, XPS, AAS and H2 chemisorption) and tested in a continuous flow system. The selected catalyst preparation protocol consists in a two-step method, which implies the deposition of palladium by ion exchange and the subsequent deposition of copper by controlled reaction on the surface of the pre-reduced palladium. The effectiveness of the catalyst in the simultaneous reduction of nitrate and hydrodechlorination of 4-chlorophenol was demonstrated. By adjusting the initial pH and the flow rate of the aqueous solution, nearly complete hydrodechlorination of 4-chlorophenol can occur together with selective nitrate reduction at a conversion of 95% and a selectivity to N2 of 92% (this value contains the contribution of all gaseous products, including the eventually formed NOx). The bimetallic catalyst was found to remains relatively stable after 100 h of test time.