Copper,cobalt and manganese: Modified hydrotalcite materials as catalysts for the selective catalytic reduction of NO with ammonia. The influence of manganese concentration

Hydrotalcites containing Cu, Co and Mn with varying manganese contents were prepared by co-precipitation. Manganese was also introduced into the catalysts via adsorption of an Mn–EDTA complex from an aqueous solution. The obtained samples were characterized by room- and high-temperature XRD, low-temperature nitrogen sorption, and FT–IR. Calcination of the catalysts at 500 °C resulted in the formation of mixed oxides with specific surface areas of 166–187 m²/g. The calcined samples were tested as catalysts for selective catalytic reduction of NO_x with ammonia. It was found that the Mn content strongly influences the product selectivity in SCR–NH₃. Mn–EDTA modified samples exhibited higher selectivity towards N₂ than Mn hydrotalcites obtained by the co-precipitation method. A hydrotalcite sample containing 5.4 wt% of manganese showed the highest catalytic activity and the lowest selectivity to N₂ at the same time.