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

Abstract

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. © 2019 Elsevier Ltd