Synthesis and functionalization of SSZ-13 as an NH3-SCR catalyst

Abstract

Hydrothermal synthesis of Na-SSZ-13 using a low concentration of the structure-directing agent N,N,N-trimethyl-1-adamantanimonium hydroxide and functionalization of the SSZ-13 framework through the introduction of Cu and Fe via ion exchange have been carried out. The prepared samples were characterized by XRD, SEM, and UV-vis spectroscopy, N₂ sorption, XRF and NH₃-TPD. It was found that relatively large iron oxide particles and well-dispersed Cu²⁺ species are formed as a result of ion exchange with iron and copper, respectively. Furthermore, the catalytic activity for NH₃ oxidation, NO oxidation and selective catalytic reduction of NO_x with ammonia (NH₃-SCR) was investigated both in the absence and in the presence of water. The functionalization of the SSZ-13 structure enhances the catalytic activity for NH₃-SCR significantly. While the NH₃-SCR activity is negligible for the Na-SSZ-13 sample, the Cu-SSZ-13 sample is highly active especially at low temperatures, and the Fe-SSZ-13 sample shows the highest activity at elevated temperatures.