Understanding the process of preparation of pure SSZ-13 via XRD and ATR-IR for selective catalytic reduction of NO_x with NH₃

SSZ-13 has attracted significant attention for gas separation and industrial catalysis applications. Here, the fabrication process of the typical Chabazite zeolite SSZ-13 was investigated by varying the synthesis parameters, and the as-synthesized crystals were characterized by x-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopy. It was found that the formation of SSZ-13 could be accelerated by an increase in the template/Al₂O₃ molar ratio from 1:1 to 7:1. However, the coexistence of analcime zeolite occurred upon further increasing the template/Al₂O₃ molar ratio to 10:1. A similar trend was found with different Na₂O/Al₂O₃ ratios (4-20) and H₂O/Al₂O₃ ratios (600-900). By varying the crystallization time (2-168 h), it was found that SSZ-13 was generated during the first 36 h, after which analcime was formed. Pure SSZ-13 zeolite could be prepared at 160 °C for 36 h. Furthermore, pure SSZ-13 zeolite and mixed zeolites were used as supports to prepare automotive catalysts via the ion-exchange method. MnO_x, FeO_x, and CuO_x supported on pure SSZ-13 showed superior catalytic activities compared with the corresponding catalysts on mixed zeolites.