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 (NO₃^-) reduction in batch and continuous mode. Complete NO₃^- removal with fast reduction kinetics (k = 18.16 × 10^-2 min^-1) and 71% selectivity toward N₂ were achieved by the Sn-Pd-kaolinite catalyst during batch reactions. During continuous tests, 100% NO₃^- removal and 80% N₂ was achieved for 60 h. However, NO₃^- removal efficiency gradually decreased to 80% in170 h. The catalyst was then successfully regenerated in the system by increasing H₂ flow which achieved a complete NO₃^- 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.