Stability of Sn–Pd-Kaolinite catalyst during heat treatment and nitrate reduction in continuous flow reaction.

In this study, a novel and highly reactive Sn–Pd catalyst supported by environmentally benign kaolinite (Sn–Pd-kaolinite) was developed and evaluated for stability for effective nitrate (NO 3 −) reduction in batch and continuous mode. Complete NO 3 − removal with fast reduction kinetics (k = 18.16 × 10−2 min−1) and 71% selectivity toward N 2 were achieved by the Sn–Pd-kaolinite catalyst during batch reactions. During continuous tests, 100% NO 3 − removal and 80% N 2 was achieved for 60 h. However, NO 3 − removal efficiency gradually decreased to 80% in170 h. The catalyst was then successfully regenerated in the system by increasing H 2 flow which achieved a complete NO 3 − removal again. The metal leaching from catalyst surface was negligible (Sn 0.01% and Pd 0.006%) and the structure was stable during the continuous test, confirming that the Sn–Pd-Kaolinite catalyst had a superior reaction kinetics and operational durability. Image 1 • A novel Sn–Pd-kaolinite catalyst was synthesized for an accelerated NO 3 − reduction. • Complete NO 3 − removal with high N 2 selectivity was achieved by the bimetallic catalyst. • The catalyst showed a remarkable durability and stability in a continuous reactor system. • Catalyst regeneration was successfully implemented with an increased H 2 flow. [ABSTRACT FROM AUTHOR]