Fully Copper‐Exchanged High‐Silica LTA Zeolites as Unrivaled Hydrothermally Stable NH₃‐SCR Catalysts

Diesel engine technology is still the most effective solution to meet tighter CO 2 regulations in the mobility and transport sector. In implementation of fuel‐efficient diesel engines, the poor thermal durability of lean nitrogen oxides (NO x ) aftertreatment systems remains as one major technical hurdle. Divalent copper ions when fully exchanged into high‐silica LTA zeolites are demonstrated to exhibit excellent activity maintenance for NO x reduction with NH 3 under vehicle simulated conditions even after hydrothermal aging at 900 °C, a critical temperature that the current commercial Cu‐SSZ‐13 catalyst cannot overcome owing to thermal deactivation. Detailed structural characterizations confirm the presence of Cu 2+ ions only at the center of single 6‐rings that act not only as a catalytically active center, but also as a dealumination suppressor. The overall results render the copper‐exchanged LTA zeolite attractive as a viable substitute for Cu‐SSZ‐13.