Mesoporous MCM-48 and MCM-41 Silicas Modified with Copper by ADP Method as Effective Catalysts for Low-Temperature NH3-SCR—The Role of Synthesis Conditions and Associated Reactions

Mesoporous silicas of MCM-41 and MCM-48 types were synthesized and modified with copper using the ammonia-driven deposition precipitation (ADP) method, resulting in highly dispersed copper species. Samples with varying copper loadings were thoroughly characterized in terms of their porous structure, metal content, copper species’ aggregation, and the stability of deposited forms under reaction conditions. Copper-modified mesoporous silicas exhibited excellent catalytic performance in the low-temperature NH3-SCR process. Their activity in NO to NO2 oxidation suggests that the fast-SCR pathway plays a significant role in NOx conversion at low temperatures. However, direct ammonia oxidation limited SCR efficiency at higher temperatures. These findings demonstrate the potential of ADP-modified copper–silica catalysts for effective and selective NOx removal under low-temperature conditions.