Low-Temperature Solid-State Ion-Exchange Method for Preparing Cu-SSZ-13 Selective Catalytic Reduction Catalyst

Solid-state ion-exchange (SSIE) is an effictive method to prepare Cu-SSZ-13, but usually requires high temperatures or assistance of NH3 for catalyst activation. Herein, an environmentally friendly low-temperature solid-state ion-exchange (LT-SSIE) method was developed. Cu salts that can decompose at temperatures lower than 300 °C (e.g., CuAc2 and Cu­(NO3)2) were chosen as Cu precursors. An impregnation method was adopted to obtain high dispersion of the precursors inside the channels of SSZ-13, as confirmed by scanning transmission electron microscopy. A calcination in air at 300 °C for 30 min was found enough for catalyst activation. In situ X-ray diffraction, diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetry, ultraviolet–visible spectroscopy and H2 temperature-programmed reduction were performed to monitor the activation prcoess of CuAc2-impregnated SSZ-13. The ion-exchange sites of SSZ-13 are occupied by Cu2+ ions originating from CuAc2 at 250–300 °C, revealing the nature of the LT-SSIE process between CuAc2 and SSZ-13.