"Pit-type Defects" strategy to improve the thermal stability of silver-based catalysts and copper-based catalysts

Metal nanoparticle (NP_S) catalysts exhibit desirable activities in various catalytic reactions. However, the sintering of metal NPs at high-temperatures even in reducing atmospheres limits its practical application. In this work, we successfully synthesized TPA-ZSM-5 with pit-type defects by treating the ZSM-5 with tetrahydroxy ammonium hydroxide (TPAOH), which was then used as a support to prepare Ag-based and Cu-based catalysts. Stability testing results show that the Ag/TPA-ZSM-5 catalyst treated at 800 °C with H₂ could maintain the high performance in NH₃-SCO and the Cu/TPA-ZSM-5 catalyst treated at 900 °C with N₂ could maintained its excellent activity in NH₃-SCR, however, the activities of Ag/ZSM-5 and Cu/ZSM-5 were drastically decreased or even deactivated after high-temperature treatment. In addition, a series of characterization analyses revealed that the excellent thermal stability is attribute to the presence of pit-type defects in the TPA-ZSM-5 as physical barriers to slow down or even inhibit the Ag NPs and Cu NPs sintering process. The strategy of using the pit-type defects to inhibit the sintering of metal NPs and improve the thermal stability can greatly enhance the practical application of catalysts.