One-pot hydrothermal synthesis of dual metal incorporated CuCe-SAPO-34 zeolite for enhancing ammonia selective catalytic reduction

A series of dual metal incorporated CuCex-SAPO-34(x = 0–0.04) samples were synthesized using one-pot hydrothermal method with diethylamine as organic structure-directing agent for selective catalytic reduction of NO x by NH 3 . The catalytic properties were elucidated in detail with physicochemical properties being analyzed using various instruments. All the catalysts exhibited typical SAPO-34 crystal structures with high specific surface areas. With the dual-metal incorporation, the surface acidity and amount of isolated Cu 2+ , which may be active sites for NH 3 -SCR, were significantly enhanced. However, excessive Ce restrained the formation of isolated Cu 2+ due to its occupation of cationic sites. Therefore, the 0.05CuCe0.02-SAPO-34 exhibited high NO conversion (≥80%) at 168°C-500°C. Furthermore, the NH 3 -SCR mechanism over different catalysts was investigated in-situ DRIFTS experiments. For the 0.05Cu-SAPO-34, the adsorbed NH 3 species react with gaseous NO and following the E-R mechanism throughout the reaction temperature range. Meanwhile, adsorbed NO 2 was detected and reacted with the adsorbed NH 3 species according to the L-H mechanism in low-temperature region. In contrast, the NH 3 -SCR reaction over the 0.05CuCe0.02-SAPO-34 primarily followed the E-R mechanism throughout the temperature range. The L-H mechanism was cut off due to the loss of the adsorption ability of nitrous species at high temperatures., resulting in NO conversion decreasing.