Rational Design of a Novel Catalyst Cu‐SAPO‐42 for NH₃‐SCR Reaction

Abstract Cu‐exchanged LTA‐type aluminosilicate catalyst has been considered as an efficient catalyst for the selective catalytic reduction of NO_x with ammonia (NH₃‐SCR). However, expensive organic structure‐directing agents (OSDAs) and the corrosive fluoride medium are inevitably used to synthesize LTA‐type molecular sieve (high‐silica LTA‐type aluminosilicate and its analogue LTA‐type silicoaluminophosphate SAPO‐42). Herein, a series of cheap and commercialized OSDAs, which are successfully applied for the targeted synthesis of SAPO‐42 in the fluoride‐free system, are identified by a novel RSS (refine, summarize, and search) approach. Furthermore, Cu‐SAPO‐42 catalysts are utilized for NH₃‐SCR. Among these catalysts, Cu‐SAPO‐42 prepared with 2‐(butylamino)ethanol (BAEA) as OSDA demonstrates the excellent activity even after hydrothermal aging at 800 °C for 16 h, which shows much better hydrothermal stability than the commercialized Cu‐SAPO‐34 catalyst with comparable Si and Cu contents. Electron paramagnetic resonance (EPR) spectroscopy and Rietveld refinement are performed to identify the locations of active Cu²⁺ ions. It turns out that the active Cu²⁺ ions are distributed near the center of single 6‐rings of the lta cage.